Journal of Applied Polymer Science受到许多中国读者喜爱，我们依据2012年的全文下载量，对2012年及以前发表在Journal of Applied Polymer Science上的文章进行了排名，以下是排名前10的文章，推荐给大家阅读。 No 1 论文标题： Electrospinning of nanofibers 作者： Thandavamoorthy Subbiah, G. S. Bhat, R. W. Tock, S. Parameswaran, S. S. Ramkumar 地址： http://onlinelibrary.wiley.com/doi/10.1002/app.21481/abstract ( 可免费阅读 ) No 2 论文标题： Characterization of polymer-layered silicate (clay) nanocomposites by transmission electron microscopy and X-ray diffraction: A comparative study 作者： Alexander B. Morgan, Jeffrey W. Gilman 地址： http://onlinelibrary.wiley.com/doi/10.1002/app.11884/abstract ( 可免费阅读 ) No 3 论文标题： Characterization of ZnO/polyaniline nanocomposites prepared by using surfactant solutions as polymerization media 作者： Kleber G. B. Alves, Jorlandio F. Felix, Etelino F. de Melo, Clécio G. dos Santos, Cesar A. S. Andrade, Celso P. de Melo 地址： http://onlinelibrary.wiley.com/doi/10.1002/app.35502/abstract No 4 论文标题： Mechanical properties of biodegradable composites from poly lactic acid (PLA) and microcrystalline cellulose (MCC) 作者： Aji P. Mathew, Kristiina Oksman, Mohini Sain 地址： http://onlinelibrary.wiley.com/doi/10.1002/app.21779/abstract No 5 论文标题： Thermal conductivity, elastic modulus, and coefficient of thermal expansion of polymer composites filled with ceramic particles for electronic packaging 作者： C. P. Wong, Raja S. Bollampally 地址： http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-4628(19991227)74:14%3C3396::AID-APP13%3E3.0.CO;2-3/abstract No 6 论文标题： Cellulose from cladophorales green algae: From environmental problem to high-tech composite materials 作者： Albert Mihranyan 地址： http://onlinelibrary.wiley.com/doi/10.1002/app.32959/abstract ( 可免费阅读 ) No 7 论文标题： Interfacial enhancement of maleated polypropylene/silica composites using graphene oxide 作者： Feng Luo, Li Chen, Nanying Ning, Ke Wang, Feng Chen, Qiang Fu 地址： http://onlinelibrary.wiley.com/doi/10.1002/app.36224/abstract No 8 论文标题： Functionalization of polypropylene at high temperature under oxidative/inert environment 作者： Deepak B. Akolekar, Shubhangi Nair, Santosh Adsul, Sunil Virkar 地址： http://onlinelibrary.wiley.com/doi/10.1002/app.34442/abstract No 9 论文标题： A study of chemical structure of soft and hardwood and wood polymers by FTIR spectroscopy 作者： K. K. Pandey 地址： http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-4628(19990321)71:12%3C1969::AID-APP6%3E3.0.CO;2-D/abstract No 10 论文标题： Estimation of the surface free energy of polymers 作者： D. K. Owens, R. C. Wendt 地址： http://onlinelibrary.wiley.com/doi/10.1002/app.1969.070130815/abstract
A multi-frequency sandwich type electromagnetic vibration energy harvester Jingdong Chen , Di Chen, Tao Yuan andXiang Chen 博士期间的第一篇SCI是关于电磁型能量采集器的论文，于2011年投稿到Applied Physics Letters上，经过5个多月的审稿和修稿，终于被接受，于2012年5月发表。Congratulations! Abstract: We proposed a multi-frequency sandwich type vibration energy harvester to widen the effective frequency range of vibration energy harvester. The harvester is composed of three resonant structures with different natural frequencies. The resonant structures are two cantilevers each with bi-layer coils and a plane spring with a magnet. The maximum peak-peak voltages of the three different frequencies are 172 mV, 104 mV, and 112mV at the frequencies of 235 Hz, 330 Hz, and 430 Hz, respectively. The first maximum voltage is much higher than the others, because the coils in both cantilevers can produce voltages. 全文链接： http://apl.aip.org/resource/1/applab/v100/i21/p213509_s1 A multi-frequency sandwich type electromagnetic vibration energy harvester.pdf
http://www.beaugrande.com/WiddowSincS.htm Large Corpora and Applied Linguistics H.G. Widdowson versus J.McH. Sinclair 1 ROBERT DE BEAUGRANDE 1. the large corpus and the language teacher In 1991, a controversy arose at the Georgetown University Round Table on Languages and Linguistics during an interchange between Henry Widdowson and John Sinclair. After carefully analysing the two published papers and separately discussing the issues with each of the two linguists, I have concluded that their respective positions are closer together than the controversy might suggest. Widdowson seems to have argued from some positions which are not actually his, and attributed to his opponent some positions which are definitely not Sinclair’s. A predictable crux of the controversy was how corpus evidence might relate to the ‘competence’ of native speakers on the one hand and to the needs of learners of English as a Foreign Language (hereafter EFL) on the other. As a noted spokesperson for applied linguistics in EFL, Widdowson (1991: 14) felt provoked by Sinclair’s typical criticisms, and cited this one: ‘we are teaching English in ignorance of a vast amount of basic fact’ (Sinclair 1985: 282). To be sure, Sinclair has not blamed the teachers, but the sources they are offered, such as dictionaries, viz: Teachers and learners have become used to a diet of manufactured, doctored, lop-sided, unnatural, peculiar, and even bizarre examples through which, in the absence of anything better, traditional dictionaries present the language. It is perhaps the main barrier to real fluency. (1988: 6f) Nonetheless, Widdowson seemed indignant that ‘linguists’ who have debarred ‘discrimination against languages’ should practice ‘discrimination against ideas about language’; and that ‘linguists have no hesitation in saying that certain ideas held by the uninformed commoner or language teacher are ill-conceived, inadequate, or hopelessly wrong’, and in ‘rubbishing the theories of colleagues with relish in prescribing their own’ (1991: 11). By these tactics, each linguist’s ‘point of view is sustained by eliminating all others, so that the diversity of experience is reduced in the interests of intellectual security’ (1991: 11). My own detailed studies of the discourse of theoretical linguists in considerable detail (e.g. Beaugrande 1991) confirm Widdowson’s remarks. But we should make due allowance for the fact than theoretical linguistics has been largely an enterprise for replacing real language with ideal language existing nowhere except in some ‘linguistic theory’ (cf. Beaugrande 1997a, 1997b, 1998a, 1998b). In consequence, the major resources for rationally adjudicating theories or models become unavailable, and debaters merely contest that ‘my idealisation is better than yours!’ A that stage, ‘rubbishing the theories of colleagues’ and ‘eliminating’ other ‘points of view’ become prominent tactics. The same mode of linguistics would naturally shower ‘ haughty disapproval, not to say disdain’ upon the attempts of ‘applied linguists to ‘appropriate’ its ‘ideas’, as Widdowson (1997: 146) has more recently complained (see Beaugrande 1998b for a riposte posted on this website). This posture is not just the ordinary casual ‘disdain’ of authentic experts for ordinary people. It is the calculated defence of a sham expertise that could be severely imperilled by applications, e.g., ones that would quickly debunk Chomsky’s (1965: 33) straight-faced denial that ‘information regarding situational context’ ‘plays any role in how language is acquired, once the mechanism’ — the ‘language acquisition device’ — ‘is put to work’ ‘by the child’. So those earlier polemic tactics ensued from replacing real language with ideal language, whereas the arguments Widdowson was castigating here were being marshalled against this very replacement by Sinclair, as they have also been by Pike, Chafe, Firth, Halliday, Hasan, Schegloff, Roy Harris, and many others. Unfortunately, the reinstatement of real language at the rightful centre of modern linguistics cannot be achieved without strenuous ‘discrimination against ideas about language’ which really are ‘ill-conceived, inadequate, or hopelessly wrong’ but which have been enthroned by linguists whose ‘theories’ must be sustained by ‘rubbishing’ the others. And, our own objective is just the opposite of ‘reducing the ‘diversity of experience’ ‘in the interests of intellectual security’; we are resolve to disrupt the unearned ‘intellectual security’ of linguists, theoretical or applied, who have indeed ‘reduced the diversity of experience’ of language and discourse and left us with a ‘trivial picture’ (Halliday 1997: 25). Widdowson’s paper proposed a contrast between the two positions. Whereas the one claims ‘objectivity’ and ‘correctness’ in ‘descriptions of language’, the other adopts ‘the relativist or pluralist position on the nature of knowledge’: The principles or equality and objectivity are comfortable illusions. Descriptions of language are not more or less correct but more or less influential, and therefore prescriptive in effect. They tell us less about truth than about power, about the privilege and prestige accorded to acknowledged authority. We cannot any longer be sure of our facts. It is not a very comfortable position to be in. (1991:11f) Despite the first person pronouns (‘us’, ‘we’), Widdowson avoided committing himself to this ‘pluralist position’, 4 but he did imply that Sinclair opposes it by invoking ‘basic fact’ ‘about which teachers were previously ignorant’ (Widdowson 1991: 12). Widdowson then posed the rhetorical question ‘what kind of fact is it that comes out of computer analysis of a corpus of text?’ (1991: 12). Characteristically, he did not answer it here or anywhere else in the paper by quoting a single ‘corpus fact’; at one point, he speculated on the ‘relative frequency’ of specific words without ‘having any evidence immediately to hand’ (1991: 17). Instead, he evoked the ‘distinction’ drawn between ‘externalised language’ versus ‘internalised language’ (1991: 12) by none other than Chomsky, the linguist who has memorably taken the most ‘relish’ in ‘rubbishing the theories of colleagues’ whilst ‘prescribing his own’. Moreover, Chomsky (1991: 89) has ‘doubted very much that linguistics has anything to contribute’ to ‘teaching’ (Chomsky 1991: 89), as Widdowson (1990: 9f) has elsewhere acknowledged even whilst rating ‘Chomsky’s position as consistent with the position I expressed’ (but see below). The genuine opposition is still between real language versus ideal language, which, I have asserted, can seriously mislead the language teaching profession. Widdowson (1991: 12-15) also invoked a further series of oppositions or dichotomies we might do well to deconstruct. These included ‘competence’ versus ‘performance’ (of course); ‘the possible’ versus ‘the performed’ (after Hymes 1972); ‘knowledge’ in ‘the mind’ versus ‘behaviour’ (Chomsky again); and ‘first person’ versus ‘third person perspective’ (Widdowson’ own theme, e.g. 1997: 158f), which should not be misconstrued as referring to the morphology of English Verbs. Sinclair was reproached for conveying the ‘clear implication’ that the corpus is identical with the language, and for excluding the first pole of each opposition whilst allowing only for the second: You do not represent language beyond the corpus: the language is represented by the corpus. What is not attested in the data is not English; not real English at any rate. what is not part of the corpus is not part of competence. What is not performed is just not possible. (Widdowson 1991: 14) Against this supposed position of ‘the work of Sinclair and his colleagues’, Widdowson quoted Greenbaum (1988: 83) that ‘the major function of the corpus is’ ‘to supply examples that represent language beyond the corpus’. But this position is just as much Sinclair’s, e.g.: ‘language users treat the regular patterns as jumping off points, and create endless variations to suit particular purposes’ (Sinclair 1991: 492). His real position should concur with the notion the collocability and colligability of the lexicogrammar of English are partly realised by the collocations and grammatical colligations of discourse and partially innovated against (Beaugrande 2000). Sinclair was astounded to be stuck in the straw-man realist position of ‘what is not attested in the data is not real English’ and ‘what is not performed is just not possible’. If he held those positions, he would stop expanding the corpus straightaway because nothing more is ‘possible’ and because any differing data would be ‘not real English’, whereas he has in fact insisted, at times to the dismay of agitated project sponsors, that the corpus must be hugely expanded. He would also have to assume that the sources of his corpus are the linguistic equivalent of the sum total all ‘possible’ sources, whereas he candidly asserts that a much wider selection of spoken data would have already been included but for severe problems of labour and expense. The evolution of modern linguistics proffers an ironic context for another one of Widdowson’s (1991: 13) polarities: ‘Chomsky’s view is that you go for the possible, Sinclair’s view is that you go for the performed’. By any realistic measure, Chomsky’s programme has always gone for the impossible , advocating, with tireless self-confidence, one project after another that never materialise and never could — a ‘grammar’ that is ‘autonomous and independent of meaning’; a solution to ‘the general problem of analysing the process of “understanding”’ by ‘explaining how kernel sentences are understood’; an account of how human ‘children’ ‘acquire language’ by ‘inventing a generative grammar that defines well-formedness and assigns interpretations to sentences even though linguistic data’ are ‘deficient’ (1957: 17, 92; 1965: 201); and more others than I have room to list here (for a thorough analysis of Chomskyan discourse, see now Beaugrande 1998b). Here we can look to Hjelmslev (1969 : 17) for the most striking formulation, this one concerning the ‘possible’: ‘the linguistic theoretician must’ ‘foresee all conceivable possibilities’, including ‘texts and languages that have not appeared in practice’ and ‘some of which will probably never be realised’ Easy enough to say once you decide (as we saw Hjelmslev do) that ‘linguistic theory cannot be verified (confirmed or invalidated) by reference to any existing texts and languages’. Chomsky (1965: 25, 27) fulfilled Hjelmslev’s vision in the most facile manner when he simply installed, by fiat, just such a ‘theory’ in the ‘language acquisition device’ of the human child: ‘as a precondition for language learning’ the child ‘must possess a linguistic theory that specifies the form of the grammar of a possible human language’ plus ‘a strategy for selecting a grammar’ by ‘determining which of the humanly possible languages is that of the community’. This is definitely not the position of Widdowson, who has firmly rejected the concept of ‘internalisation’ by means of a ‘universal Chomskyan language acquisition device’ (1990: 19). The conception of the ‘possible’ is too abstract to be very useful for language pedagogy anyway. Learners of English as a non-native language produce many utterances which may not seem possible to the teacher’s intuition, but, as I have noted, we are currently finding new motives for doubting the reliability of intuition. Far more relevant is what is or is not both ‘possible’ and ‘performed’ at the learners’ current stage of skills and knowledge , since that is all we can realistically hope to build upon. There, we can productively orient our approach toward large corpora of learners’ English , such as have been collected by Sylviane Granger at the University of Louvain (cf. Granger 1996) and by John Milton at the Hong Kong University of Science and Technology (cf. Milton and Freeman 1996). Such data can also systematically alert teachers and learners to typical problems such as language interference. Another of Widdowson’s polarities we might deconstruct is the one between ‘knowledge’ in ‘the mind’ versus ‘behaviour’, the latter term perhaps reminding language teachers of behaviourist pedagogy and Skinnerean behaviourism. 5 But linking a large corpus with behaviour and behaviourist methods would be flawed for at least two reasons. The more obvious reason is that the behaviourist ‘audio-lingual’ method with its pattern drills and prefabricated dialogues was based on mechanical language patterns more than on authentic data; it equated language with behaviour in order to reduce language, whose relative complexity it could not grasp, to behaviour, whose relative simplicity seemed ideal for ‘conditioning’, ‘reinforcement’ and so on; and the method was backed up by heavy behaviourist commitments with in general pedagogy and by the prestige and authority of American military language institutes, where ‘drills’ are literally the ‘order of the day’. Nor does Sinclair advocate a teaching method whereby learners parrot back corpus data; on the contrary, he has expressly counselled against ‘heaping raw texts into the classroom, which is becoming quite fashionable’, and in favour of having ‘the patterns of language to be taught undergo pedagogic processing’ (1996). The more subtle reason is that corpus data are not equivalent to ‘behaviour’ in the ‘externalised’ sense which Widdowson’s polarities imply and which is often encountered in discussions of pedagogy, e.g., when a ‘syllabus’ ‘identifies’ ‘behavioural skills’ (Sinclair 1988: 175). Instead, they are discourse , and the distinction is crucial. External behaviour consists of observable corporeal enactments, of which the classic examples in behaviourist research were running mazes, pulling levers, and pressing keys. Discourse is behaviour in that externalised sense only as an array of articulatory and acoustic operations, or, for written language, of inscriptions and visual recognitions; and no one has for a long time — certainly not Sinclair — proposed to describe language in those terms, nor does a corpus represent language that way. When discourse realises lexical collocability and grammatical colligability by means of collocations and colligations, the ‘performed’ continually re-specifies and adjusts the contours of the ‘possible’. In parallel, ‘knowledge’ in ‘the mind’ decides t he significance of the ‘behaviour’. Sinclair’s true position is that these operations are far more delicate and specific than we can determine without extensive corpus data. Moreover, analysing corpus data is less equivalent to observing behaviour than to participating in discourse . We thus move on to deconstruct Widdowson’s polarity between ‘first person’ versus ‘third person’: The description of internalised language requires a first person perspective. You really have no choice if you are seeking to prise knowledge out from the recesses of the mind: knowledge which is not realised as behavioural evidence available to the observer Corpus linguistics adopts the third person perspective and only describes what can be observed, reveal ‘member categories’ of the speech community itself which account for their intuitions about the language. (1991: 15) On the contrary: corpus linguists can reveal the ‘member categories’ they themselves hold and apply as ‘members of the speech community’ sharing what (Sinclair 1991: 498) would call the ‘general acculturation’ of the intended ‘target reader’. They too are deeply concerned with ‘the pragmatic use of the language in the transaction of social business’ and ‘the interaction of social relations’, which Widdowson would reserve for ‘discourse analysis’ 6 while boxing ‘corpus linguistics of the COBUILD kind’ into a ‘text analysis’ concerned only with ‘performance frequencies’ (1991: 13). Especially for data from public sources, corpus linguists can readily adopt a first person perspective as potential speaker (e.g., how I might use language to stress national prosperity , ); a second person perspective as a potential addressee (e.g., how I might react to a discourse about national prosperity when all I can see is isolated pockets of prosperity among the rich); and a third person perspective (e.g., how the general populace might be persuaded by such discourse to vote in the interests of the rich). All this resembles what ordinary speakers and hearers do, and discourse analysts as well. Having plenty of data can trigger intuitions that might otherwise lie untapped if you were just trying to ‘prise knowledge out from the recesses of the mind’, which sounds like shelling a stubborn walnut. The ‘difficulty’ with ‘generative linguists’ ‘acting as their own informants’ and ‘drawing introspectively on their own competence’ is not just, as Widdowson (1991: 15) commented, that ‘they are also members’ of ‘the community of linguists with all its disciplinary sub-culture of different and incompatible attitudes and values’. A more severe difficulty is that these linguists have in effect disowned that membership in order to arrogate to themselves the authority of the ‘ideal speaker-hearer’. Thus, Chomsky has denied that the (presumably real) ‘speaker of a language’ ‘is aware of the rules of the grammar or even’ ‘can become aware of them’; so ‘a generative grammar attempts to specify what a speaker actually knows, not what he may report about his knowledge’ (1965: 8). By implication, linguists who assume the role of the speaker are claiming, simply by virtue of holding an academic degree in ‘linguistic theory’, to command superhuman powers for ‘becoming aware of and reporting’ what other speakers cannot. Presumably, the ‘kernel sentences’ they invent, like the man hit the ball , would in turn be perfect data; and these — or at least their ‘underlying’ order or ‘deep structure’ — would be far more suited to represent ideal language than real data would be. So it would not be at all ‘disturbing for the claims of corpus linguistics if there were disparities between’ ‘what people indicate they would say in a given context’ and ‘what they actually do say in such contexts’ (Widdowson 1991: 17). Quite the contrary: compare Widdowson’s (1991: 17) view that ‘the correspondence between what people claim they would say and what they actually do say cannot be taken on trust’ with Sinclair et al.’s (1990: xi) view that ‘any such points emerging from a set of constructed examples could not, of course, be trusted’. Sinclair does not attribute this lack of ‘trust’ to people being ‘ignorant’ and ‘hopelessly wrong’, which Widdowson (1991: 11f) suggests he does; the obstacle is simply that many constraints upon what people say, as I have pointed out, only emerge during the actual discourse — what people do say and not just what they would say. The final Widdowsonian polarity (one I already cited) we might deconstruct is between ‘internal’ or ‘I-language’ versus ‘external’ or ‘E-language’ appropriated from Chomsky’s more recent work. ‘I-language’ in Chomsky’s own sense is quite irrelevant to Widdowson’s argument, being a universal code which is common to all languages and which is not accessible to the interventions of language teachers because it is genetically and biologically installed and implemented in fine detail: ‘there is a highly determinate, very definite structure of concepts and of meaning that is intrinsic to our nature, and as we acquire language or other cognitive systems these things just kind of grow in our minds, the same way we grow arms and legs’ (Chomsky 1991: 66). Moreover, when Chomsky now ‘speculates’ ‘that there may be only one computational system and in that sense only one language’, his ‘radically different’ ‘post-1980s theories’ have ‘no constructions; there are no rules’, ‘that is, language-specific rules’ (1991: 81, 92). What Sinclair wants to describe and Widdowson surely wants to teach would still be ‘E-languages’, which Chomsky (1986: 25) has shrugged aside as ‘epiphenomena at best’. Similarly, if ‘the distinction between I-language and E-language description refers to what aspects of language are to be described’ (Widdowson 1991: 15), the description of a Chomskyan ‘I-language’ would be utterly useless for language teaching, which has to deal extensively with ‘language-specific rules’ and ‘constructions’; and, as noted, ‘I-language’ is not teachable at all. Or again, Widdowson means something quite different than Chomsky does, and their ‘positions’ are not so ‘consistent’ after all (see above). Besides, even if ‘I-language’ versus ‘E-language’ are informally taken to designate what speakers know of their language versus what they say in the language, the distinction between the two could not be the same for native language learning (or ‘acquisition’), where extensive knowledge is indeed acquired without ordinary learning, versus non-native language learning, where that same acquired knowledge needs to be revised, often consciously, to accommodate knowledge of the non-native language (Beaugrande 1997b). And the same distinction might be unstable and inconsistent for the same speaker in different contexts and for different speakers in the ‘same’ context. The special qualities of corpus data indicate that this instability and inconsistency are a natural reflex of the huge range and variety of constraints emerging on the plane of the actual discourse (Beaugrande 2000). So the evolving dialectic between ‘possible’ versus’ ‘performed’ in Hymes’ terms, or between ‘I-language’ versus ‘E-language’ in Widdowson’s (but not Chomsky’s) terms, or between Chomsky’s ‘competence’ versus ‘performance’ would best account both for the ‘fluency’ language teachers seek to instil and for the regularities in large corpus data. I can see no sound justification for cordoning off the two sides of any of these polarities in order to insulate the activities of teachers from those of corpus analysts, as Widdowson’s reservations seem to suggest even whilst, a bit inconsistenly, he is accusing Sinclair of trying to discard the first term of each polarity. In another source, Widdowson (1990: 18) has proposed yet another polarity between what language learners know versus how they perform: ‘acquisition having to do with knowledge’ versus ‘accuracy having to do with behaviour’. The first term is problematic: for Halliday (1973: 24), ‘acquisition’ is a ‘misleading metaphor, suggesting that language’ is ‘property to be owned’. The term was mainly promoted when generative linguists decided to invent an account which was pointedly distinct from ‘learning’ — a distinction later exploited by Krashen to discredit established methods of language learning by reciting his airy that ‘learning cannot become acquisition’ (e.g. Krashen 1985: 22, 24, 41, 48, 55) (see now Beaugrande 1997b). The second term is problematic too insofar as corpus data indicate that many of the detailed decisions on the plane of the actual discourse are not properly determined by criteria of ‘accuracy’ but of ‘appropriateness’ as defined by Hymes and cited by Widdowson (1990: 13) among the criteria belonging to ‘E-language’, whereas Widdowson apparently consigns ‘knowledge of language’ to ‘I-language’; besides, criteria of ‘accuracy’ can have the practical effect (noted below) of ranking conformity high above creativity. Perhaps we might agree to distinguish instead between a person’s ‘language capability’ and ‘language achievement’; or between ‘known options’ versus ‘selected options’; or between ‘available regularities’ versus ‘on-line decisions’. A further polarity in that same other source cited Bialystok and Sharwood-Smith’s (1985) ‘difference between knowledge of language’ versus ‘the ability to access that knowledge effectively’, with the implication that the ‘variation may either be because these forms are tied in some way to a particular kind of context and so are not freely transferable or because the second context imposes inhibiting conditions which prevent learners from accessing and applying what they know’ (Widdowson 1990: 18). This position sounds reasonably compatible with Sinclair’s, since corpus data are quite helpful for telling in fine detail which ‘forms are tied to a particular kind of context’, and indeed suggest that such ‘tyings’ are the rule rather than the exception, at least in English. And precisely this fine detail may be a submerged crux of the language teaching controversy, hinging upon an inclination of foreign language teaching, and one Widdowson himself opposes, to ‘set a high premium on correctness’: ‘the imposition of correctness’ ‘has the effect of inhibiting the learners’ engagement of relevant procedures for mediation acquired through an experience of their own language’ (Widdowson 1991: 121, 124). Learners may arrive at the intimidating misconception that there must be a ‘correct’ answer ‘rule’ for everything detail, may besiege the teacher to tell them what it is, as reported by Kova … i … (1998) for teaching English in Slovenia . This practice concurs only too well with a ‘linguistic theory’ wherein ‘language consists of a set of rules for the combination of words into well-formed and meaningful sentences’ (Sinclair and Renouf 1984: 76; cf. Beaugrande 1998b). The crux would now revolve around be the danger of corpus research getting misinterpreted (to stay with Widdowson’s terms) as demonstrations of the accurate things language learners must say rather than the appropriate things the learners should take as their framework of orientation for what they say. Only then would the teaching and learning of EFL be saddled with the doomed precept that ‘w hat is not attested in the data is not real English’. If this be Widdowson’s real anxiety, it would be heartily shared by Sinclair and his team, witness the Collins COBUILD English Grammar ‘that contains a lot of productive rules; these rules are not restrictive, they are “do not” rules; they are “try this one” rules where you can hardly go wrong’ ( Sinclair 1991: 493; cf. Sinclair et al. 1990: 493). Moreover, the same anxiety might profoundly disturb language teachers about large-corpus data if they viewed these as a colossal compilation of fine-grained ‘prescriptions’ that must be ‘drilled’ into the learners on top of the usual ‘grammar’ and ‘vocabulary’. Sinclair has on numerous occasions espoused the opposite view, viz.: More adequate description will so organise the detail that it largely falls in line with the meaning, and becomes easy, rather than difficult, to learn. If the grammatical choices turn out in the main to be also lexical choices, then a massive simplification can be expected. I f on top of that, grammar is seen as a springboard for creativity rather than as an instrument of social discipline, the pleasure to teaching and learning can increase enormously. (Sinclair 1991: 497) These prospects reinforce the advocacy repeatedly lodged in my own paper against separating of ‘grammar’ from ‘vocabulary’, which pull the unity of the language apart. Francis and Sinclair (1994: 200) in turn warn against ‘presenting learners with syntactic structures’ and ‘then presenting lexis separately and haphazardly as a resource for slotting into these structures’; ‘we should not burden learners with vast amounts of syntactic information on the one hand, and lexical (“vocabulary”) information on the other, which they then have to match according to principles which are not naturally available to them as non-native speakers’. Nor again should the relative frequency statistics in corpus data be misinterpreted as the degrees of obligation for teachers to prescribe and enforce the various usages. Such could be one implication of Widdowson’s (1991: 20) reservation that ‘language prescriptions for the inducement of learning’ ‘cannot be modelled’ on ‘the frequency profiles of text analysis’. He notes that language teaching may have sound reasons for presenting data ‘because they are useful, not because they are frequently used’ (1991: 20), and that artificially simplified data would be fully admissible under this provision. Sinclair, in contrast, would recommend simplifying language teaching by restricting the presentation of artificial data in ways to prevent learners overgeneralising by not knowing the authentic constraints. This recommendation is reasonably compatible with some positions adopted by Widdowson elsewhere, e.g.: there is a great deal that the native speaker knows of his language which takes the form less of unanalysed grammatical rules than adaptable lexical chunks. are, of course, subject to differing degrees of sentence modification. At one end of the spectrum, we have fixed phrases that cannot be dismantled; at the other end, we have collocational clusters which can be freely adjusted as sentence constituents. native speakers do not exercise the creative potential of syntactic rules to anything like their full extent indeed if they did so they would not be accepted as exhibiting native-like control of the language ; anybody producing these syntactic variants of fixed idiomatic phrases would nevertheless be adjudged incompetent in the language. (1989: 132f) Here again, corpus data could offer language teachers handy ways for estimating the status of their grammatical and lexical materials along the parameter between ‘fixed phrases’ versus ‘collocational clusters’. ‘Widdowson’s point about unpredictable gaps in corpora’ (Sinclair 1991: 493) needs further clarification too. Just as an array of choices in a corpus can, as a whole, be highly improbable or even unique in a statistical sense , there will be many arrays which do not happen to show up in a corpus but which could be readily produced and comprehended by native speakers of the language. Yet insofar as these arrays are related to productive regularities that are implemented in the corpus data, they do not properly constitute ‘gaps’. Sinclair (and I) would predict that in a corpus of the size of the Bank of English, all of the really significant productive regularities of English will be represented, but also that we will always find ‘patterns for which there is some evidence, but insufficient to make a conclusive case for significance’ (1991: 491). The gravity of this problem should steadily recede as the corpus arrives at higher orders of magnitude. At that stage, I would be surprised if we discover regularities (not specific wordings like flip-flop or roger ) which both are not represented in corpus data and yet are judged essential by teachers of EFL. Clarification might be helpful once more when Widdowson (1991: 18) asserted the ‘intuitive significance’ and ‘psychological reality’ of ‘kernel sentences’, which ‘may not be authentic as units of behaviour’, but which ‘are the stock in trade of language teaching’. As with ‘I-language’, Widdowson must be using the term in a looser sense than Chomsky (1957: 106f), for whom the ‘kernel of basic sentences’ must be ‘simple, declarative active with no complex verb or noun phrases’. By this definition, the ‘ stock in trade of language teaching’ would be to feed learners on invented data like the man hit the ball and the cat sat on the mat , but not the next man at bat was hit by a knuckle ball , or the striped cat continued to sleep on the mat , let alone innocuous authentic data like the lion and the unicorn were fighting for the crown , black sheep, have you any wool? , or Polly, put the kettle on! Surely Widdowson meant simple sentences, and only they have genuine ‘intuitive significance’ and ‘psychological reality’. He may be concerned lest corpus data not be appropriately simple for the earlier stages of EFL; but the regularities most simply implemented in such sentences are of course represented in corpus data as well. Perhaps Widdowson would be content if a specially selected corpus of appropriate data could be compiled to fit the levels of simplicity he would recommend. At least, in a recent discussion (January 1997) he approved of my proposal (elaborated in Beaugrande 1998a) to offer both teachers and learners access to browse through strategically selected and sorted ‘model corpora’, guided by user-friendly walk-throughs. They could work together in exploring for themselves not just contemporary English and other languages, but specific social, regional, and registerial varieties of a language, including ones being spoken as non-native languages in relevant pedagogical, academic, or professional settings. Learners could also receive user-friendly rough-and-ready training for working together in describing the regularities they can find in the data. Here, I would advocate replacing the traditional term and concept of rules, which has accumulated far too much prescriptive and authoritarian baggage, with the term and concept of reasons. The replacement would be sound both on grounds of theory, because speakers certainly do not follow ‘rules’ in the sense of either traditional or formalist ‘grammar’ for every choice they make but nearly always have ‘reasons’; and on grounds of practice, because ‘rules’ carries disempowering connotations of authorities, compulsions, violations, and punishment. Learners should be reassured that they are basically ‘reasonable’ and deserve to know the ‘reasons’ why they should do or say things, and to have their own ‘reasons’ respected. Moreover, we would help to rebalance creativity with conformity, since appropriate contexts supply good reasons to choose creatively on the basis of a steadily more ‘delicate’ sensitivity toward the typical collocations and colligations. Browsing through a learner-oriented corpus on one’s own pacing and initiative might finally eliminate much of the stress, anxiety, and indifference fostered by conventional language teaching with its focus on ‘accuracy’ or ‘correctness’ . The learners who actively invest their creativity in discovering other people’s ‘reasons’ could thus gain substantial initiative and authority during the overall process of learning, with a matching rise in interest and motivation as compared to the passive, alienating, and mechanical application of ‘rules’ laid down by teachers or textbooks. A fascinating prospect would be to make the enterprise cumulative. Advanced learners could guide the newcomers though the browsing procedures and share their own results. Also, the total results could be accumulated in a data base which could eventually serve to formulate the first learner-generated grammar and lexicon in the history of language education. Such a work would be an impressive implementation of the principle of learners taking charge of their own learning processes, long advocated by democratic educators like Paulo Freire (1985 ). Co-operative browsing might be an excellent activity for dispelling the misunderstandings and anxieties language teachers may harbour about large-corpus data. The misunderstandings I wish to dispel here concerns the positions attributed to John Sinclair. He by no means asserts that any corpus, however large, equals the total or ‘real English’; or that the ‘performed’ equals the ‘possible’. What he does assert is that the difference between those data and regularities which are found in a very large corpus versus those which are not should be significant for people who purport to make authoritative statements in textbooks or reference works about ‘real English’, especially when addressing learners of English who will try to put the statements into practice. Sinclair also asserts that the same difference is significant for the competence of adult native speakers, who are likely to say combinations that are frequent in the corpus and are unlikely to say combinations that are infrequent or do not occur, although they certainly can say the latter in appropriate contexts. Such speakers have an intuitive sense of which combinations are common, sensible, useful, and so on, without at all implying that others are ‘just not possible’ or ‘not real English’. Their ‘ immediate intuitive response this is part of competence and of a well ordered view of language’ (Sinclair 1996) Furthermore, Sinclair asserts that the data and regularities which do appear frequently in a large corpus should be relevant and interesting for teachers and learners of English as a native language and even more as a foreign language. And finally, he asserts that taking corpus data into account could improve the quality of English world-wide because non-native learners would have much more detailed models and targets to aim for (Sinclair 1996). 2. conclusion and outlook I have tried to explain why some major ‘revisions’ are on the cards for both theoretical linguistics and applied linguistics, and why, rather than ‘ fearing for our future work’, we may justly sustain some refreshing optimism. I have suggested that many important problems facing our work in both theory and practice have been artificially fostered by ill-advised moves to replace real language with ideal language. A natural and unfortunate consequence has been the symptomatic ‘antipathy to data’, which Sinclair (1997: 8) invokes, and which may now mislead language teachers about the vital opportunities offered by finally having access to vast amounts of authentic language data. We might ponder Sinclair’s (1994) allegory of the church authorities who refused to look through Galileo’s telescope lest they see that the earth is not the eternal centre of the universe; so also might language authorities refuse to work with corpora lest they see that their ideal ‘language’ (or I-language’) is not the eternal centre of human ‘competence’ or the true sphere of ‘linguistic universals’. Most importantly, perhaps, large-corpus data can provide an really effective counter-weight for the deeply ingrained insecurity many speakers have about the real language they themselves produce, whether native or foreign. Corpus data reveal how skilled ordinary speakers actually are; and how the real language they produce is, as Sinclair (1991: 492) writes, ‘ exhilarating creative, marvellously unpredictable, wayward, unruly, quite incredibly productive’. notes 1 I am deeply indebted to John Sinclair for discussing a number of the issues raised here and for providing access to his Bank of English terminal and to his unpublished materials. I also profited from discussions with Henry Widdowson, Michael Halliday, Sid Greenbaum, Clive Holes, Elena Tognini-Bonelli, Jeremy Clear , John Milton, and Nigel Turton . 2 Ironically, ‘langage’ was precisely Saussure’s term for ‘speech’, as compared to ‘parole’ (translated as ‘speaking’)! 3 On these terms, compare already Firth (1968); Greenbaum (1974). The term ‘preferences’ is elaborated in Louw (1993); Sinclair (1994). Sinclair’s term ‘prosodies’ for ‘prosodies’ for ‘the attitudinal meanings that emerge once you extend the phrase sufficiently far — the point where the surface patterns of language give way to meaningful choices’ (1996) could be misunderstood as referring to intonation. 4 Yet Widdowson seemed a bit inconsistent later: ‘discourse analysts tend more and more towards the relativism’, and ‘to the extent that they favour direct confrontation with actual data, they make common cause with the text analysis of corpus linguistics’ (1991: 16). In my view, a restrictive separation between ‘discourse analysis’ versus ‘text analysis’ hardly seems justified nowadays; but Widdowson might well think so (compare Note 6). 5 Such could be one reading of Sinclair’s remark about ‘dealing with uncomfortable material’ ‘by tying it to a discredited methodology’ (1991: 490). 6 Widdowson certainly has his own special views on what ‘discourse analysis’ should be — it was the topic of his unpublished thesis at university — and has recently signed contract to write a book about it. references Beaugrande, R. de. 1991. Linguistic Theory: The Discourse of Fundamental Works . London: Longman. Beaugrande, R. de. 1997a. New Foundations for a Science of Text and Discourse . Greenwich, CT: Ablex. Beaugrande, R. de. 1997b. ‘Theory and practice in applied linguistics: Disconnection, conflict, or dialectic?’ Applied Linguistics 18/3: 279-313. Beaugrande, R. de. 1997c. ‘On history and historicity in modern linguistics: Formalism versus functionalism revisited.’ Functions of Language 4/2: 169-213. Beaugrande, R. de. 1998a. ‘Society, education, linguistics, and language: Inclusion and exclusion in theory and practice.’ Linguistics and Education . Beaugrande, R. de. 1998b. ‘Performative speech acts in linguistic theory: The rationality of Noam Chomsky.’ Journal of Pragmatics 29: 1-39 . Beaugrande, R. de. 1998c. ‘ On ‘usefulness’ and ‘validity’ in the theory and practice of linguistics : A riposte to H.G. Widdowson.’ Functions of Language 5/1: 87-98 . Beaugrande, R. de. 2000. ‘Text linguistics at the millennium: Corpus data and missing links’. Text 20. Bialystok. E. and M. Sharwood-Smith. 1985. ‘Interlanguage is not a state of mind: An evaluation of the construct for second language acquisition.’ Applied Linguistics 6/2: 101-117. Chomsky, N. 1957. Syntactic Structures . The Hague: Mouton. Chomsky, N. 1965. Aspects of the Theory of Syntax . Cambridge: MIT Press. Chomsky, N. 1986. Knowledge of Language . New York: Praeger. Chomsky, N. 1991. ‘Language, politics, and composition’ in G. Olsen and I. Gales (eds.) Interviews: Cross- d isciplinary p erspectives on r hetoric and l iteracy . Carbondale: Southern Illinois University Press, 61-95. Francis, G. and J.McH. Sinclair. 1994. ‘I bet he drinks Carling Black Label: A riposte to Owen on corpus grammar.’ Applied Linguistics 15: 190-200. Freire, P. 1985 . Pedagogia do oprimido . Rio de Janeiro: Editora Paz e Terra. Granger, S. 1996. ‘Learner English around the world’ in S. Greenbaum (ed.) Comparing English World-Wide: The International Corpus of English . Oxford: Clarendon, 13-24. Greenbaum, S. 1988. Good English and the Grammarian . London: Longman. Halliday, M.A.K. 1973. Explorations in the Function of Language . London: Arnold. Hjelmslev, L. 1969 . Prolegomena to a Theory of Language . Madison: University of Wisconsin Press. Hymes, D. 1972. ‘On communicative competence’ in J. Pride and J.S. Holmes (eds.) Sociolinguistics . Harmondsworth: Penguin, 264-293. Kova … i … , I. 1998. ‘Relating grammar to discourse, or: Can grammar classes be like poetry classes?’ in R. de Beaugrande, M. Grosman, and B. Seidlhofer (eds.) Language Policy and Language Education in Emerging Nations: Focus on Slovenia and Croatia . Greenwood, CT: Ablex. Krashen, S. 1985. The Input Hypothesis: Issues and Implications . London: Longman. Milton, J. and R. Freeman . 1996. ‘Lexical variation in the writing of Chinese learners of English’ in C.E. Percy, C.F. Meyer, and I. Lancashire (eds.) Synchronic Corpus Linguistics: Papers from the Sixteenth International Conference on English Language Research on Computerized Corpora . Amsterdam: Rodopi, 121-131. Pawley, A. and F. H. Snider . 1983. ‘Two puzzles for linguistic theory: Native-like selection and native-like fluency’ in J. C. Richards and R. Schmidt (eds.) Language and Communication . London: Longman. Saussure, F. de. 1966 . Course in General Linguistics (transl. Wade Baskin). New York: McGraw-Hill. Sinclair, J.McH. 1985. ‘Selected issues’ in R. Quirk and H.G. Widdowson (eds.) English in the World . Cambridge: Cambridge University Press, 11-24. Sinclair, J.McH. 1988. New Directions in English Dictionaries. Unpublished manuscript. Sinclair, J.McH. 1991. ‘Shared knowledge’ in J. Alatis (ed.) Georgetown University Round Table on Languages and Linguistics 1991 . Washington, D.C.: Georgetown University Press, 489-500. Sinclair, J.McH. 1994. ‘Large Corpora Are Here to Stay.’ Lecture at the University of Vienna, June 1994 (on video). Sinclair, J.McH. 1996. ‘What Do We Know about Language, How Do We Get to Know It, and What Has All That Got to Do with Language Teaching?’ Paper at the International Conference on Analysis and Description: Applications to Language Teaching, at Lignan College and at the Hong Kong University of Science and Technology, June 1996 (on video). Sinclair, J.McH. and A. Renouf . 1984. ‘A lexical syllabus ofr language learning’ in J.McH. Sinclair et al. Lexis and Lexicography . Singapore: National University Press, 75-95. Widdowson, H.G. 1989. ‘Knowledge of language and ability for use.’ Applied Linguistics 10/2: 128-137. Widdowson, H.G. 1990. Aspects of Language Teaching . Oxford: Oxford University Press. Widdowson, H.G. 1991. ‘The description and prescription of language’ in J. Alatis (ed.) Georgetown University Round Table on Languages and Linguistics 1991 . Washington, D.C.: Georgetown University Press, 11-24. Widdowson, H.G . 1997. ‘The use of grammar, the grammar of use.’ Functions of Language 4, 2: 145-168.
http://eca.state.gov/education/engteaching/pubs/BR/functionalsec4_10.htm Genre Approaches 10 Applied Genre Analysis and ESP Vijay K. Bhatia More than simply an act of linguistic description, discourse analysis is a linguistic explanation attempting to answer the question, why members of specific discourse communities use the language the way they do. Taking communicative purpose as the key characteristic feature of a genre, this paper will first highlight some of the major features of genre theory which make it attractive for application to language teaching. The second section discusses how a genre-based approach to language learning and teaching helps the learner to use language purposely. The final section illustrates a genre-based approach to language teaching using examples from materials designed for specific professional contexts. Introduction Recent work in applied genre analysis (Swales, 1981a, 1990; Bhatia, 1983a, 1993; Dudley-Evans, 1986; Berkenkotter and Huckin, 1995) has reiterated the importance of linguistic analysis in the practice of language teaching. Discourse analysis is viewed not simply as an act of linguistic description but more as linguistic explanation, attempting to answer the question, why do members of specific discourse communities use the language the way they do? The answer requires input not from linguistics alone, but equally importantly, fro sociolinguistic and ethnographic studies, psycholinguistic and cognitive psychology, communication research, studies of disciplinary cultures and insights from members of such discourse communities, to name only a few crucial sources of information. Taking communicative purpose as the key characteristic feature of a genre, the analysis attempts to unravel mysteries of the artifact in question. Genre analysis thus, has become one of the major influences on the current practices in the teaching and learning of languages, in general, and in the teaching and learning of ESP and English for Professional Communication (EPC), in particular. In this paper I would like to demonstrate the use of genre theory to the teaching of ESP. I will do this in the following three sections. 1. The first section will highlight some of the major characteristic features of genre theory which make it attractive for applications to language teaching. 2. The second section will discuss how a genre-based approach to language learning and teaching helps the learner to use language purposefully. 3. The final section will illustrate a genre-based approach to language teaching by taking examples from materials designed for specific professional contexts. What Is Genre Analysis? Genre analysis is the study of situated linguistic behavior in institutionalized academic or professional settings. It has the following four characteristics. * Rather than providing a detailed extension, validation or otherwise of one linguistic framework or the other, genre analysis shows a genuine interest in the use of language to achieve communicative goals. In this sense, it is not an extension of linguistic formalism. * However, genre analysis does not represent a static description of language use but gives a dynamic explanation of the way expert users of language manipulate generic conventions to achieve a variety of complex goals. In this sense, it combines the advantages of a sociolinguistics perspective, especially the use of ethnographic information, with those of a cognitive perspective, especially regarding the tactical use of language. * It is primarily motivated by applied linguistic concerns, especially language teaching at various levels. * It is narrow in focus but wide in vision, focussing on specific differentiation in language use at various levels of generality. Genre-Based Approach To ESP In my view, there are at least four distinct, though systematically related, areas of competence that an ESP learner needs to develop in order to get over his or her lack of confidence in handling specialist discourse. Even if most of these learners already possess a reasonably adequate competence in the use of the language for general every day functions, they will still need to develop a. understanding of the specialist code, b. familiarity with the dynamics of specialist genres, which includes the rhetorical forms and content, c. specific contexts they respond to and the conventions they tend to use in their responses, and finally, d. a proficiency in the manipulation of specialist genres to respond to the exigencies of unfamiliar and novel situations. In other words, learners need to develop the understanding of code, the acquisition of genre knowledge associated with the specialist culture, sensitivity to cognitive structuring of specialist genres and then, and only then, can they hope to exploit generic knowledge of a repertoire of specialist genres by becoming informed users of the discourse of their chosen field. The following elaborates each of these four stages. (1) Knowledge of the Code The knowledge of the code, of course, is the pre-requisite for developing communicative expertise in specialist or even everyday discourse. Most of the ESL programs all over the world aim to achieve this with varying degrees of success. However, it is important to note that an almost perfect knowledge of the code is neither necessary nor sufficient for successful ESP instruction, though it does seem to be a popular myth that we language teachers often believe. This myth has gained popular currency among many ESP teachers who believe that any form of ESP work requires almost perfect competence in the use of the code. Where teachers hold such a belief, further ESL instruction invariably incorporates tedious remedial teaching, often resulting in less than satisfactory consequences. We often fail to recognize that if seven to eight years of ESL instruction have failed to equip the learner with this desired level of competence, further remedial work, because of its essentially repetitive nature, will be far less effective. The other side of the myth is that if somehow second language learners can be given so called underlying linguistic competence , then there is no need to develop ESP competence because the learners will be able to cope with the flow of new information in any subject discipline, just as a native speaker does. This claim, at best, seems to be grossly overstated and, at worst, seriously flawed. The claim seems to rest on the somewhat naive assumption that the main difference between everyday use of language and specialist discourses lies in the use of specialist lexis. However, much of the work done in discourse and genre analysis in professional and academic contexts in the last two decades strongly suggests that there are fundamental differences in the use of lexico-grammatical, semantico-pragmatic and discoursal resources in specialist genres. (2) Acquisition of Genre Knowledge To participate in a specialist communicative event, one must acquaint oneself not only with the communicative goals of a particular discourse community, but also with the communicative goal-oriented purposes associated with specific use of genres. Therefore, before learners undertake any goal-driven communicative activity, they need to become aware of appropriate rhetorical procedures and conventions typically associated with the specialist discourse community they aspire to join. Genre knowledge of this kind is a form of situated cognition,which appears to be inextricable from professional writers' procedural and social knowledge (Berkenkotter and Huckin, 1995:13). Learners need to acquire genre knowledge, procedural knowledge (which includes a knowledge of tools and their uses as well as their discipline's methods and interpretive framework), and social knowledge (in the sense of familiarity with the rhetorical and conceptual context) in order to become better informed apprentices. As Fairclough (1992) points out, ... a genre implies not only a particular text type, but also particular processes of producing, distributing and consuming texts. (3) Sensitivity to Cognitive Structures Having understood the goals of the specialist community and to some extent internalized some of the conventions associated with specialist genres used by them, the learner will then need to become familiar with the way language is typically used to achieve these goals and communicative purposes. In addition, learners will need to exploit these conventions in response to changing socio-cognitive demands in specific professional contexts or certain novel situations and purposes. This can be developed by sensitizing learners not only to the generic forms and content in genre-specific texts but also to their emerging responses to changes in social practices. Surprisingly, even after specialist learners become reasonably competent in language for everyday situations, they may still need further knowledge of the code. Recent research in the study of a variety of academic and professional genres (see Bhatia, 1983a, 1992, 1993) indicates that although there can be large areas of overlap in the use of lexico-grammatical resources across various professional contexts, there certainly are specific uses of lexico-grammatical features which carry typically genre-specific values in specialized contexts. Swales (1981b) has investigated the use of definitions in student writing in science, textbooks in economics, and legislation and found that the distribution, the form, and the functional value these definitions carry differ radically in the three genres. More recently, Bhatia (1992) has found that the use of nominals in advertising, scientific academic genres, and legislation differs significantly in terms of their form, distribution, and discoursal values. These and similar findings of this nature indicate that just as certain lexical items have specialist meanings in specific professional genres, a number of syntactic forms may also carry genre-specific restricted values in addition to their general meanings codified in grammar books. Therefore, it is imperative that the specialist learner become aware of restricted aspects of linguistic code in addition to the general competence he or she requires in the language. Genre-based grammatical explanations raise learners' awareness of the rationale of the text-genre that they are required to read and write. Rather than simply learning to read and produce a piece of text as a computer does, students should develop a sensitivity to the conventions in order to ensure the pragmatic success of the text in the appropriate academic or the professional context. As Swales so aptly noted, ... A genre-centered approach is likely to focus student attention on rhetorical action and on the organizational and linguistic means of its accomplishment. (4) Exploitation of Generic Knowledge It is only after learners have developed some acquaintance or, better yet, expertise at levels discussed above, that they can confidently interpret, use or even take liberties with specialist discourse. The first three stages mentioned above mostly involve understanding conventions, whereas this last stage includes exploiting and taking liberties with conventions to achieve pragmatic success in specified professional contexts. Genre-Based Approach In Action Case one : UNDP-Government of Singapore self-access project The genre-based approach to ESP materials development for ESP is relatively new. Following is a description of the UNDP-Government of Singapore Project in the Teaching of English in Meeting the Needs of Business and Technology undertaken to develop EBT (English for Business and Technology). These materials were used on a self-access basis to supplement the existing mainline programs at the then two polytechnics in Singapore.1 The materials are primarily based on the description of authentic linguistic data, where the focus is not just on the language (lexico-grammar and cognitive structure) but also on the conventions and procedures that shape the genres in question. The materials, therefore, do not simply promote the awareness of the linguistic system underlying a particular genre but also offer genre-specific explanations as to why certain features of language realize specific values in individual genres. The underlying principle, therefore, is to take the learner from pure descriptive linguistic tasks towards genre-specific explanations of why such linguistic features are used and to what effect. The intent is to help the learner to use language more effectively in academic and professional settings and to bring much-needed psychological reality and relevance to the learning task. The approach to genre analysis and materials design seeks to clarify rather than prescribe. Once learned and adequately understood, the conventions and procedures can be exploited creatively to achieve private ends within the socially recognized communicative purposes. Each unit is devoted to a specific (sub)genre and consists of a head text followed in most cases by a set of three head worksheets. The head text represents a standard or model example of the particular (sub)genre and sets out the main rhetorical moves or steps needed for its adequate realization by color-coding each move. Each head text is followed by a set of three head worksheets. Head worksheet 1 is meant to help the learner internalize the interpretative generic structure of the genre in question. This highlights the main discoursal strategies that are conventionally exploited to achieve communicative ends in specific academic and professional settings. This worksheet gives the learner what Carrell (1983) refers to as formal schemata in the form of discoursal conventions that are typically associated with the genre. Head worksheet 1 in the Business volume, for example, begins with a head text, which is taken as a standard or model example of a sales promotion letter (See Bhatia and Tay, 1987:1). After the learners have read the head text, they are provided with a detailed explanation of the communicative purpose of the (sub)genre and the various Moves the writer makes use of to achieve that purpose. The Moves are also color-coded in the head text in order to make them obvious to the learner. The explanation contains no technical or other difficult vocabulary, except the names of the Moves, which are kept in simple terms. The purpose of such an explanation is to provide the learner with what Carrell (1983) refers to as 'content schemata' which the learner uses to understand the strategies that an expert genre writer employs to achieve his communicative purpose(s). The explanation can be given on the audio or video tape or in written form. The teacher must first ensure that the learners have understood and internalized both a typical communicative structure (formal schema) and the conventionalized patterns of knowledge, beliefs and experience of the specialist community associated with the genre in question. The head worksheet gives further practice to the learner in the following three aspects of genre construction and comprehension: 1. Acquisition of the knowledge of the promotional genre through explanation 2 Sensitization to generic form and content through analysis 3. Use and exploitation of generic knowledge through variation in contexts. Each exercise is, therefore, preceded by significant explanation of the strategy used by the author to achieve his or her intention. Exercise 2, for example, is not simply a mechanical exercise in the identification of various Moves in the genre, but it also introduces the learner to different ways of establishing credentials, (see exercise A below), including a case where the author needs to skip such a conventional realization of the first Move , as in exercise B below (slightly modified versions from Bhatia and Tay, 1987: 5). Exercise 2 A Explanation The writer of a promotional letter can use the Move ESTABLISHING CREDENTIALS not only by (1) referring to the needs of the business world in general or the needs of a customer in particular as in Mr. Huff's letter but by (2) referring to his own company's achievements/speciality as well. In the following example, C E Holidays, the name synonymous with the very best in travel trade with 20 years of professional expertise, will present you with a variety of programmes. the writer ESTABLISHES CREDENTIALS by stating his company's past experiences and field of specialization. Either of these two strategies or, both may realize this Move. Instructions Label the following text to indicate how many different strategies the author uses in ESTABLISHING CREDENTIALS of his company. The next 12 months are going to be difficult ones for Singapore industries as a whole. We, at Marco Polo are fully aware of the current market situation and are continuously upgrading our facilities and amenities to meet new competition. B Explanation In certain cases when the company has had past business dealings with the customer, the writer does not need to ESTABLISH CREDENTIALS. Instead, the writer can choose to begin the letter by thanking the customer for his continued support. The following is an example of this kind. You have now been a member of International Airline Passenger Association for about three months. Your continuing support keeps our worldwide organization strong and we want you to know that we appreciate your confidence in our services. Instructions Label the strategies that the author uses in the following text examples to ESTABLISH CREDENTIALS. (1) With the current economic downturn we would like to take this opportunity to express our sincere appreciation for your support during the past months. (2) Have you ever wished there was one study providing you with a step-by-step guide to establish a joint venture in the People's Republic of China? Head worksheet 2 focuses mainly on the linguistic realizations of various rhetorical moves and the genre as a whole. Although the worksheet is meant to provide practice in the use of appropriate language, the grammatical explanation offered at each stage is invariably genre-specific, and therefore, more relevant to the task in hand. The following is an example taken from Head Worksheet 2 (Bhatia and Tay, 1987: 9-11). Head worksheet 3 (not shown here) gives more advanced practice in free genre writing. It often concentrates on refinement and creative variation in style, grammatical appropriateness and other aspects of genre construction, like editing and revision, often using easification devices (see Bhatia, 1983b). Another significant aspect in these exercises is that they all make use of more or less authentic, (though grammatically imperfect and stylistically weak and inadequate) examples from the real world. This is much more useful for learning purposes than texts especially written with inserted lexico-grammatical or stylistic errors. Learners are more likely to face realistic errors actually committed by a professional or academic community than those invented by the teacher. Exercises in this worksheet also take the learner systematically from relatively simple and controlled to more complex and advanced free genre writing. (Bhatia and Tay, 1987: 26-27). Head Worksheet 2 Exercise 1 (A) Explanation The writer of a promotional letter establishes the importance of his company either by referring to the business needs in general and the customer needs in particular or by referring to his company's achievements/speciality. There are certain typical language features which characterize the different ways of establishing credentials. For instance, notice the use of the pronouns, you/we and the general/specific references in the examples that follow. 1. Referring to the customer's needs: Have you ever thought how much time your typist wastes in taking down your letters? Pronominal Reference: You 2. Referring to the general business needs: Every woman dreams of having at least one really beautiful coat and here is a splendid opportunity to make that dream come true. General Reference: Every woman 3. Referring to the company's achievements/speciality: We are fully aware of the current market situation and are continuously upgrading our facilities and amenities to meet new competition. Pronominal Reference: We C E Holidays, the name synonymous with the very best in the travel trade, present you with a wide variety of tour programmes. Specific Reference: Name of the Company - C E Holidays' Instructions Now, observe the use of references in the following sentences and tick them under the headings given to indicate the two ways (needs/achievements) of establishing credentials. 1. Are you deafened by the ceaseless noise of typewriters and calculating machines? 2. Why do thousands of people who normally suffer from the miseries of cold weather wear thermotex? 3. At the Ideal Home Exhibition, which opens at Earl Court on 21 June, we have attractive new designs in furniture, and many new ideas. 4. How can project managers plan and effect strategies which facilitate the accomplishments of an I/S project? 5. We at Wright Services are experienced Management Consultants with experience in industries as diverse as mining, banking and manufacturing. Customer's needs General business needs Company' achievements/ speciality Check with Answer Sheet (B) Explanation Instructions Now observe that in the following examples, the writer refers to his company's achievements/speciality in two ways: 1. Factual evidence: He not only states that a product/service is good but also presents some data in the form of facts and figures to illustrate its worth. EXAMPLE: C E Holidays, the name synonymous with the very best in the travel trade, with 20 years of professional expertise, will present you with a wide variety of tour programmes. Factual evidence : 20 years of professional expertise 2. Unsupported generalizations and high pressure talk: He states that a product/service is efficient without presenting specific reasons and explanations to prove its worth. EXAMPLE: Unsupported generalizations continuously upgrading our facilities and amenities. Instructions Indicate in the boxes which of the sentences below uses factual evidence or unsupported generalizations in referring to the company's achievements/specialty. 1. We, the experienced carpet-markets, guarantee our carpets to last for 10 years. We use oriental wool exclusively-- every fibre of wool is at least 12 inches long and our carpets have 400 knots to every square inch. 2. We at Tech Craft make the best plastic pipes on the market today. They represent the very best in chemical research. 3. How would you like to have solar heating installed in your home at 50% actual cost? 4. What would you say to a gift that gave you a warmer and more comfortable home, free form draughts and a saving of over 20% in fuel costs? Factual evidence Unsupported generalizations Check with Answer Sheet (C) Improve the following sentences by providing factual evidence. 1. We have insulated a large number of houses and reports from all over confirm that there is a considerable reduction in the fuel bill after insulation. 2. In Singapore, LEP International Ltd. has been operational for a long time and the services offered by our aircargo division include in and out-bound aircargo consolidation, import clearance, cargo delivery and collection and warehousing in the Changi Airport complex. 3. The Valuation Department of this firm has been in existence since the setting up of the firm's office and now comprises many qualified valuers. Although the materials in their present form contain only one set of worksheets called the head worksheets, several sets of additional worksheets have been prepared to bring in more variety focussing more and more on advanced creative aspects of genre construction, use and exploitation. Case Two : MA in Law and Language, City University of Hong Kong Context The MA in Law and Language program at the City University of Hong Kong is a unique postgraduate programme designed for those professionals in various industrial, management and bureaucratic institutions who although not legal experts are nevertheless required to be able to read, understand, interpret, translate and sometimes write legal documents as part of their daily professional activities. As part of the program, they have one module on English for Law, which trains them in the use of English in typical legal settings. Although able to use English in their every day life when they find it necessary, they understandably feel quite nervous when handling legal language, especially legal rules and regulation, legal agreements and contracts. As part of their daily routine, most of them are often required, among other things, to read, interpret, translate and explain ordinances, legislative acts, contracts and agreements to their superiors and quite often to members of the general public. Communicative Needs These students need to develop some of the following skills. * The ability to understand why legal documents are written the way they are * The ability to understand how these documents are constructed, interpreted, and used * The ability to read and clarify these legal documents for the benefit of lay audiences And, most of all, * The acquisition of increased self-confidence, and sensitivity to the use of legal genres by acquiring genre skills, including those of rhetorical consciousness Meeting the needs: Integrating Process, Product and Purposes Without specifying the details of methods and materials used, I would like to discuss one of the units based on the use of a single text in order to develop some of the skills I have referred to in the preceding paragraphs. Preparatory Work The learners are assumed to be linguistically competent. They are given background information about the contexts in which legislative rules are drafted, interpreted, and used in legal settings. Particular attention is paid to the dual characteristics of legal rules, i.e., clarity, precision, and unambiguity, on the one hand, and all-inclusiveness, on the other. The learners are then given sufficient practice in analysis of legislative sentences, focusing especially on the use of lexico-grammatical devices which are typically used to make their interpretation and use certain as well as flexible. Particular attention is paid to the identification and use of complex-prepositional phrases and qualificational insertions to make rules clear, precise, and unambiguous and binomial expressions to make them all-inclusive. Considerable attention is also paid to cognitive structuring typically associated with legislative sentences. In addition, the learners are given some practice in identifying psycholinguistic problems resulting from discontinuities in syntax as a result of qualificational insertions. This all requires approximately ten to twelve hours of work. It also involves the use of several typical textual illustrations in the class and as part of individual and/or group work. Illustrative Material At this stage the learners are introduced to the notion of easification for the specialist audience and simplification for the lay audience, which are introduced as two different genres, because they serve two different communicative purposes, and are meant for two different audiences. As illustrated in Bhatia (1983b and 1993: 145), easification is an attempt to make a professional text more accessible to the learner by using a variety of devices which guide the reader without making any drastic changes to the original content of the text. In the legislative context, the most appropriate and useful easification devices include those which not only clarify the cognitive structuring in the expression of complex legal contingencies but also reduce the information load at particular points in legislative statements. These easification procedures make the text easier to process while preserving the generic integrity of the original. Simplification procedures, on the other hand, create alternative textualizations meant for a lay audience. The following example illustrates one easification device: Look at the following sections from an agreement between the publishers and the author, and complete the tasks given at the end. Original Version The author hereby warrants to the Publishers that the author has the right and power to make this Agreement and that the Work is the Author's own original work, except for material in the public domain and such excerpts from other works as may be included with the written permission of the copyright owners, and will in no way whatever give rise to a violation of any existing Copyright, or a breach of any existing agreement, and that the Work contains nothing defamatory or libelous and that all statements contained therein purporting to be facts are true and that nothing in the Work is liable to give rise to a criminal prosecution or to a civil action for damages or any other remedy and the author will indemnify the Publishers against any loss, injury or expense arising out of any breach or alleged breach of this warranty. The Publishers reserve the right to alter or to insist the Author alter the text of the Work in such a way as may appear to them appropriate for the purpose of removing or amending any passage which on the advice of the Publishers' legal advisers may be considered objectionable or likely to be actionable at law without affecting the Author's liability under this Clause in respect of any passage not so removed or amended. The foregoing warranties and indemnities shall survive the termination of this agreement. Tasks 1. Analyze the text in terms of linguistic features discussed in the previous sessions. Also discuss whether and to what extent the use of these features help the writer to make this text clear, precise, unambiguous, and all- inclusive. 2. What seems to be the communicative purpose of the text? Is this to regulate future legal relationship between the Publishers and the Author? If so, can this be written in a more accessible manner? Write an easier version of this section and discuss its implications. 3. How would you simplify the content of this section for a non-specialist audience who simply would like to be informed about the content of the clause? A typical response to task (2) of easification for specialist audience is reproduced here for comparison. Easified Student Version (1) The author hereby warrants to the Publishers that (a) the author has the right and power to make this Agreement, and (b) the Work is the Author's own original work, except for material in the public domain and such excerpts from other works as may be included with the written permission of the copyright owners, and will in no way whatever give rise to a violation of any existing Copyright, or a breach of any existing agreement, and (c) the Work contains nothing defamatory or libelous, and (d) all statements contained therein purporting to be facts are true and, (e) nothing in the Work is liable to give rise to a criminal prosecution or to a civil action for damages or any other remedy, and (f) the author will indemnify the Publishers against any loss, injury or expense arising out of any breach or alleged breach of this warranty. (2) The Publishers reserve the right to alter or to insist the Author alter the text of the Work in such a way as may appear to them appropriate for the purpose of removing or amending any passage which on the advice of the Publishers' legal advisers may be considered objectionable or likely to be actionable at law without affecting the Author's liability under this Clause in respect of any passage not so removed or amended. (3) The foregoing warranties and indemnities shall survive the termination of this agreement. The simple change in format helps the students find the hierarchy of ideas in the text. GAINS A quick comparison of the two versions demonstrates the self-confidence the learner seems to have gained in handling complexities of legal discourse and the extent to which he or she has become sensitive to the specific demands imposed on informed readership of such documents. It also indicates the internalization and use, among other things, of the following abilities and strategies typically used in the construction, and interpretation of specialized genres associated with the legal culture, which include an ability to cope with the complexities of legal syntax in legislative contexts, to handle the use of excessive information load in the legislative sentence, to use textual-mapping devices in the expression of complex contingencies, and to distinguish communicative purposes in the two versions used above. Similar work is also carried out in the use of legal cases and judgments before the learners are given some training in handling matters of intertextuality and interdiscursivity in various legal genres. An approach like this establishes the importance of generic integrity in ESP work on the one hand, and that of generic creativity on the other. The main advantage of such a genre-based approach to the teaching and learning of specialist English is that the learner does not learn language in isolation from specialist contexts, but is encouraged to make the relevant connection between the use of language on the one hand and the purpose of communication on the other, always aware of the question, why do members of the specialist discourse community use the language in this way? This develops in the learner an explicit desire to participate consciously in the professional community, rather than just being able to read and write legal texts as a computer does, without being a participant in the communicative event. This awareness of participation in the ownership of the genres of legal culture is what Swales (1990) calls raising rhetorical consciousness in the learner. On the language teaching side, this may also be seen to represent a conscious effort to integrate the product, process, and communicative purpose in a meaningful context. Dr. Vijay K Bhatia is an Associate Professor in the Department of English at the City University of Hong Kong. His main research interests are discourse and genre analysis, legal English, other academic and professional genres, cross-cultural communication, ESP and EPC. He has served on the editorial advisory board of English for Specific Purposes, RELC Journal and World Englishes. He has published in most of the major journals in applied linguistics, ESP and discourse analysis. His most recent publication is Analyzing Genre -- Language Use in Professional Settings (1993). Note: 1. The resulting two volumes of materials were the outcome of the joint effort of a team of EBT specialists and practicing teachers representing the three participating institutions, namely, the National University of Singapore, Ngee Ann Polytechnic and Singapore Polytechnic. Volume 1 contains materials to be used in English for Business and Volume 2 in English for Technology.
8.5.1 Applied Bias Potential A simple negative DC bias potential can be applied directly to an electrically conducting surface which can be the cathode of a DC diode discharge. Bombardment will be relatively uniform over flat surfaces where the equipotential field lines are conformal to the surface, but will vary greatly if the field lines are curved since ions are accelerated normal to the field lines. The DC diode discharge that is generated will fill the deposition chamber volume if the pressure is sufficiently high, although the plasma density will vary with position in the chamber. In the application of a DC potential, often the applied voltage and current (power—watts/cm 2 ) to the surface are used as process parameters and control variables . However it must be realized that the bombarding ions generally have not been accelerated to the full applied potential due to the position of their formation, charge exchange collisions, and physical collisions in the gas. The measured current consists of the incident ion flux (the ions may be multiply charged) and the loss of secondary electrons from the surface . The cathode power is a useful process parameter to maintain reproducibility only if parameters such as gas composition, gas pressure, system geometry, etc., are kept constant. The bias can be in the form of a low frequency AC potential but the pulsed DC bias is becoming more common . The pulsed DC bias (Sec. 4.4.3) uses a bipolar square waveform operating at 10–100 kHz and is an AC-type of configuration where the on-off time and pulse polarity can be varied . – During the off-time, plasma species can move to the substrate surface and neutralize any charge build-up . The current-voltage behavior of the discharge changes during the pulse. Initially the impedance is high , giving a high voltage and low current. As the discharge develops , the impedance is lowered, the voltage decreases, and the current increases. The behavior of the impedance depends on the composition of the gas . For example, the impedance change will be greater for an oxygen discharge than for an argon discharge. The pulsed DC bias technique can be used to allow bombardment of electrically insulating films and surfaces without arcing and allow more unifom bombardment of irregular surfaces. A radio-frequency (rf) bias potential (Sec. 4.4.6) can be applied to the surface of the substrate or depositing film when the surface or film is an electrical insulator to allow high energy ion bombardment. The rf also prevents charge buildup on the surface which will result in arcing over the surface or through the insulating film if it is thin. When applying an rf potential , the potential of the surface in contact with the plasma will be continuously varying, though it will always be negative with respect to the plasma . The DC bias of the surface with respect to the plasma will depend on the rf frequency , the electrode areas , the presence of blocking capacitance in the circuit and whether an external DC bias supply is present . The energy of the ions that bombard the surface will depend on the frequency of the rf and the gas pressure . Maximum bombardment energy will be attained at low frequencies and low gas pressures. When using rf sputtering as a vapor source, a different rf frequency and power can be used on the substrate than is used on the sputtering target. The rf bias has the advantage that it can establish a discharge in the space between the electrodes at a pressure lower than that required for a DC bias . It has the disadvantage that the rf electrode is like a radio antenna and the plasma density formed over the surface depends on the shape of the substrate/fixture system . In all cases, ground shields should be kept well away from the rf electrode since the rf power can then be coupled directly to ground and not the plasma. In the case of an insulating substrate , the substrate must completely cover the rf electrode or the exposed metal will provide a low resistivity (short) between the metal electrode and the plasma . When using an rf bias, the rf can be coupled into the fixture without electrical contact. This is an advantage when using moving fixturing and tooling. A combined DC bias and rf bias can be applied if an rf choke is used in the DC circuit to prevent the rf from entering the DC power supply. By applying a DC bias along with the rf bias , the insulating surface is exposed to bombardment for a longer period of time during the rf cycle.
4.3.2 Applied Bias Potentials Because the electrons have a very high mobility compared topositive ions, it is impossible to generate a high positive bias on a surfacein contact with a plasma . The negative potential between the plasma and asurface can be increased by applying an externally generated negativepotential to the surface. This applied potential can be in the form of acontinuous Direct Current (DC), pulsed DC, alternating current (AC) orradio-frequency (rf) potential. This applied bias can accelerate positiveions to the surface with very high energies .
Forthcoming papers of International Journal of Applied Mechanics (IJAM) Vol.2 No.4: 1. Atomistically-Informed Mesoscale Model Of Deformation And Failure Of Bioinspired Hierarchical Silica Nanocomposites, Dipanjan Sen, Markus J. Buehler, ( Massachusetts Institute Of Technology, USA ) 2. Single Walled Nanotubes As Kirchoff Elasticas, Prabhat K. Agnihotri And Sumit Basu ( Indian Institute Of Technology, India ) 3. Fracture Testing Of Nanoscale Thin Films Inside The Transmission Electron Microscope, Sandeep Kumar, M. A. Haque ( Pennsylvania State University, USA ) 4. Effect Of Non-Uniform In-Plane Pulsating Edge Loading On Dynamic Stability Of Stiffened Shell Panels With Cutouts, Shuvendu Narayan Patel, ( Indian Institute Of Technology, India ) 5. Thermal Effect On The Bending Behavior Of Curved Functionally Graded Piezoelectric Actuators, Mostafa Zaman Zhi Yan Liying Jiang ( University Of Western Ontario, Canada ) 6. Elastic-Plastic Modeling Of Cast In-738 Superalloy Single Fusion Welds, Edison A. Bonifaz (University Of Manitoba, Canada) 7. Elasto-Viscoplastic Wave Thermometry For Single Crystalline Silicon Processing, Xuele Qi, Li Liu, C. Steve Suh And Ravi Chona ( Texas AM University, USA ) 8. Logarithmic Singularity In A Crack Problem, Y. Z. Chen ( Jiangsu University, China ) 9. Wkb Method And Buckling Of A Neo-Hookean Cylindrical Shell Of Arbitrary Thickness Subjected To An External Hydrostatic Pressure, Murteza Sanjarani Pour ( University Of Sistan Balochestan, Iran ) 10. 3-D Rock Mass Geometrical Modeling With Arbitrary Discontinuities, Guoyang Fu, Lei He, Guowei Ma ( Nanyang Technological University, Singapore; The University Of Western Australia, Australia ) 11. A Hybrid Scheme For Three-Dimensional Incompressible Two Phase Flows, Cai Li, Zhou Jun, Zhou Feng-Qi, Xie Wen-Xian ( Northwestern Polytechnical University, China )
以下为美国一所也许并非最顶尖的高校的 Applied Math colloqia，该colloqia还受到企业赞助，这里可见到不少著名专家的报告 。 Seminars for 2009-2010 May 20, 2010: Nancy Kopell , Boston University Gamma, beta and cell assemblies: brain rhythms from physiology to function May 6, 2010: Michael Brenner , Harvard University Adventures in self-assembly Abstract: Self assembly is the idea of creating a system whose component parts spontaneously assemble into a structure of interest. In this talk I will outline our research program aimed at creating self-assembled structures out of very small spheres, that bind to each other on sticking. The talk will focus on (i) some fundamental mathematical questions in finite sphere packings (e.g. how do the number of rigid packings grow with N, the number of spheres); (ii) algorithms for self assembly (e.g. suppose the spheres are not identical, so that every sphere does not stick to every other; how to design the system to promote particular structures); (iii) physical questions (e.g. what is the probability that a given packing with N particles forms for a system of colloidal nanospheres); (iv) comparisons with experiments on colloidal nanospheres. and (v) ways of using microfluidics to enable kinetically driven self assembly. April 1, 2010: Athanasios Fokas , Cambridge University Integrability, imaging, and complexification Abstract: Ideas and techniques of Integrability have had a significant impact in several areas of science and engineering. In this lecture, two such applications will be reviewed: (a) an analytical approach to certain important medical imaging techniques; (b) a unified approach to analyzing boundary value problems. The latter approach unifies the fundamental contribution to the analytical solution of PDEs of Fourier, Cauchy and Green, and also presents a non-linearization of some of these results. February 25, 2010: Leslie Greengard , Courant Institute A new formalism for electromagnetic scattering in complex geometry Abstract: We will describe some recent, elementary results in the theory of electromagnetic scattering. There are two classical approaches that we will review - one based on the vector and scalar potential and applicable in arbitrary geometry, and one based on two scalar potentials (due to Lorenz, Debye and Mie), valid only in the exterior of a sphere. In extending the Lorenz-Debye-Mie approach to arbitrary geometry, we have encountered some new mathematical questions involving differential geometry, partial differential equations and numerical analysis. This is joint work with Charlie Epstein. February 4, 2010: George Papanicolaou , Stanford University Imaging with noise Abstract: It is somewhat surprising at first that it is possible to locate a network of sensors from cross correlations of noise signals that they record. This is assuming that the speed of propagation in the ambient environment is known and that the noise sources are sufficiently diverse. If the sensor locations are known and the propagation speed is not known then it can be estimated from cross correlation information. Although a basic understanding of these possibilities had been available for some time, it is the success of recent applications in seismology that have revealed the great potential of correlation methods, passive sensors and the constructive use of ambient noise in imaging. I will introduce these ideas in an interdisciplinary, mathematical way and show that a great deal can be done with them. Things become more complicated, and a mathematically more interesting, when the ambient medium is also strongly scattering. I will end with a review of what is known so far in this case, and what might be expected. January 14, 2010: Charlie Doering , University of Michigan Heat rises: convection, stability and turbulence Abstract: Rayleigh-Bnard convection is the buoyancy-driven flow that results when a fluid is heated from below and cooled from above sufficiently to destabilize the conduction state where the fluid is at rest. A key experimental, theoretical, and mathematical challenge is to ascertain the functional dependence of the heat transport on the applied temperature drop and on the material parameters characterizing the fluid. Turbulent convection is of particular interest. In this talk we will review some of the history and scientific applications of Rayleigh-Bnard convection, describe some theory and analysis connecting notions of nonlinear stability to the statistical dynamics of the highly unstable turbulent regime, and compare the results with direct numerical simulations and laboratory experiments. November 19, 2009: Jason Fleischer , Princeton University Optical hydrodynamics Abstract: It is well-known that the basic equations of nonlinear optics can be mapped to equations from condensed matter physics. For example, the nonlinear Schrdinger description of paraxial beam propagation is identical to the Gross-Pitaevskii treatment of coherent matter waves, e.g. for Bose-Einstein Condensates. In turn, these equations can be mapped to Euler-like fluid dynamics using a polar (Madelung) transformation. Here, we exploit these relations to develop an optical hydrodynamics. For coherent waves, we examine dispersive shock wave formation, hydrodynamic instabilities, and vortex flow. For incoherent waves, we demonstrate all-optical plasma dynamics, including Landau damping, bump-on-tail instabilities, and weak and strong regimes of spatial turbulence. Optical experiments are performed and shown to match very well with theory. The results establish optical systems as an analog simulator for fluid behavior and suggest a variety of fluid solutions to photonic problems, including those of imaging. November 5, 2009: Phil Holmes , Princeton University Neuromechanics of lamprey swimming or, an elastic rod with a mind of its own Abstract: Locomotion provides superb examples of cooperation among neuromuscular systems, environmental reaction forces, and sensory feedback. As part of a program to understand the neuromechanics of locomotion, here we construct a model of anguilliform (eel-like) swimming in slender fishes. Building on a continuum mechanical representation of the body as an viscoelastic rod, actuated by a traveling wave of preferred curvature and subject to simplified hydrodynamic reaction forces, we incorporate a new version of a calcium release and muscle force model, fitted to data from the lamprey Ichthyomyzon unicuspis, that interactively generates the curvature wave. We use the model to investigate the source of the difference in speeds observed between electromyographic waves of muscle activation and mechanical waves of body curvature, concluding that it is due to a combination of passive viscoelastic and geometric properties of the body and active muscle properties. Moreover, we find that nonlinear force dependence on muscle length and shortening velocity may reduce the work done by the swimming muscles in steady swimming. October 22, 2009: Russel Caflisch , UCLA Multiscale methods for dilute fluids and plasmas Abstract: Fluids and plasmas exhibit a variety of spatial and temporal scales that lead to interesting physical phenomena and difficult computational challenges. One of the most difficult of these is due to the difference between the continuum (fluid) and the collisional (particle) length scales. For a dilute gas or plasma, the effect of particle collisions is not accurately approximated by a continuum description, so that its evolution requires a particle description such as the Boltzmann equation. Numerical simulation of the Boltzmann equation is usually performed using a Monte Carlo method such as Direct Simulation Monte Carlo (DSMC). Near the fluid limit, however, DSMC becomes computationally intractable, because of the large collision rate. To overcome this problem we have developed a hybrid method that combines a continuum (fluid) description and a particle (DSMC) description. Numerical examples for both fluids and plasmas will be presented to illustrate the performance of the methods. PreviousSeminars April 9, 2009: Marty Golubitsky , Ohio State University Symmetry-Breaking; Synchrony Breaking Abstract: A coupled cell system is a network of interacting dynamical Coupled cell models assume that the output from each cell is important and that signals from two or more cells can be compared so that patterns of synchrony can We ask: which part of the qualitative dynamics observed in coupled cells is the product of network architecture and which part depends on the specific equations? In our theory, local network symmetries replace symmetry as a way of organizing network dynamics, and synchrony-breaking replaces symmetry-breaking as a basic way in which transitions to complicated dynamics occur. Background on symmetry-breaking and pattern formation will be presented. Marty Golubitsky is Distinguished Professor of Mathematics and Physical Sciences at the Ohio State University, where he serves as Director of the Mathematical Biosciences Institute. He received his PhD in Mathematics from M.I.T. in 1970 and has been Professor of Mathematics at Arizona State University (1979-83) and Cullen Distinguished Professor of Mathematics at the University of Houston (1983-2008).Dr. Golubitsky works in the fields of nonlinear dynamics and bifurcation theory studying the role of symmetry in the formation of patterns in physical systems and the role of network architecture in the dynamics of coupled systems. His recent research focuses on some mathematical aspects of biological applications: animal gaits, the visual cortex, the auditory system, and coupled systems. He has co-authored four graduate texts, one undergraduate text, and two nontechnical trade books, (Fearful Symmetry: Is God a Geometer with Ian Stewart and Symmetry in Chaos with Michael Field) and over 100 research papers. Dr. Golubitsky is a Fellow of the American Academy of Arts and Sciences, a Fellow of the American Association for the Advancement of Science (AAAS), the 1997 recipient of the University of Houston Esther Farfel Award, and the 2001 co-recipient of the Ferran Sunyer i Balaguer Prize (for The Symmetry Perspective). He has been elected to the Councils of the Society for Industrial and Applied Mathematics (SIAM), AAAS, and the American Mathematical Society. Dr. Golubitsky was the founding Editor-in-Chief of the SIAM Journal on Applied Dynamical Systems and has served as President of SIAM (2005-06). Printable poster May 21, 2009: Nick Trefethen, Oxford University Chebfuns: a new kind of numerical computing Abstract: Chebfuns represent a new kind of computing that aims to combine the feel of symbolics with the speed of precision numerics. The idea is to represent functions by piecewise Chebyshev expansions whose length is determined adaptively to maintain an accuracy of close to machine. The software is implemented in object-oriented Matlab, with familiar vector operations such as sum and diff overloaded to analogues for functions such as integration and differentiation, and the chebop extension solves linear ordinary differential equations by typing a backslash. This is joint work with others including Zachary Battles, Folkmar Bornemann, Toby Driscoll, Ricardo Pachon, and Rodrigo Platte. Nick Trefethen is Professor of Numerical Analysis and head of the Numerical Analysis Group at Oxford University. A Fellow of the Royal Society and a member of the National Academy of Engineering, he is known for books, articles, and software in areas including numerical linear algebra, transition to turbulence, approximation of functions, numerical conformal mapping, and spectral methods for partial differential equations. Printable poster January 29, 2009: Claude Le Bris, Paris Mathematical challenges in molecular simulation: an overview Abstract: Molecular simulation is increasingly important in many engineering sciences and life sciences. The field has only been recently explored by mathematical analysts and numerical analysts, leading to several achievements, but also leaving major challenging issues unsolved, both theoretically and computationally. The talk will present the state of the art and will review major mathematical issues of practical importance and theoretical relevance. It will also relate such issues of molecular simulation with issues in materials science. It is mostly based on a recent article coauthored with E. Cances and PL. Lions, and published in Nonlinearity, volume 21, T165-T176, 2008. Claude Le Bris is a Professor of Applied Mathematics at the Ecole Nationale des Ponts et Cahussees, Paris. He is also Civil engineer-in-chief, Associate Professor at the Ecole Polytechnique and scientific director of the MICMAC project (multiscale methods) at INRIA. Professor Le Bris has won numerous awards including the Blaise Pascal Prize 1999 from the French Academy of Sciences, the CS 2002 Prize in Scientific computing from Communications Systems, and the Giovanni Sacchi-Landriani Prize 2002 from the Lombard Academy of Arts and Sciences. Printable poster February 12, 2009: Thomas Hou, Caltech Recent progress on dynamic stability and global regularity of 3D incompressible Euler and Navier-Stokes equations Abstract: Whether the 3D incompressible Navier-Stokes equations can develop a finite time singularity from smooth initial data is one of the seven Millennium Open Problems posted by the Clay Mathematical Institute. We review some recent theoretical and computational studies of the 3D Euler equations which show that there is a subtle dynamic depletion of nonlinear vortex stretching due to local geometric regularity of vortex filaments. The local geometric regularity of vortex filaments can lead to tremendous cancellation of nonlinear vortex stretching, thus preventing a finite time singularity. Our studies also reveal a surprising stabilizing effect of convection for the 3D incompressible Euler and Navier-Stokes equations. Finally, we present a new class of solutions for the 3D Euler and Navier-Stokes equations, which exhibit very interesting dynamic growth property by exploiting the special structure of the solution and the cancellation between the convection term and the vortex stretching term, we prove nonlinear stability and the global regularity of this class of solutions. Thomas Hou is the Charles Lee Powell Professor and Executive Officer of Applied and Computational Mathematics at the California Institute of Technology. Professor Hou has won numerous awards including the Sloan Fellowship (1990-1992), the Feng Kang Prize in Scientific Computing (1997), the APS Francois N. Frenkiel Award (1998), the SIAM James H. Wilkinson Prize in Numerical Analysis and Scientific Computing (2001), the Morningside Gold Medal in Applied Mathematics, International Congress of Chinese Mathematicians (2004), and the Computational and Applied Sciences Award, the United States Association of Computational Mechanics (2005). In addition, he is on numerous editorial boards including as the founding editor of the SIAM Journal on Multiscale Modeling and Simulation. Printable poster February 26, 2009: Carl Bender, Washington University Quantum Mechanics in the Complex Domain Abstract: The average quantum physicist on the street believes that a quantum-mechanical Hamiltonian must be Dirac Hermitian (symmetric under combined matrix transposition and complex conjugation) in order to be sure that the energy eigenvalues are real and that time evolution is unitary. However, the Hamiltonian H=p^2+ix^3,for example, which is clearly not Dirac Hermitian, has a real positive discrete spectrum and generates unitary time evolution, and thus it defines a perfectly acceptable quantum mechanics. Evidently, the axiom of Dirac Hermiticity is too restrictive. While the Hamiltonian H=p^2+ix^3 is not Dirac Hermitian, it is PT symmetric; that is, it is symmetric under combined space reflection P and time reversal T. In general, if a Hamiltonian H is not Dirac Hermitian but exhibits an unbroken PT symmetry, there is a procedure for determining the adjoint operation under which H is Hermitian. It is wrong to assume a priori that the adjoint operation that interchanges bra vectors and ket vectors in the Hilbert space of states is the Dirac adjoint. This would be like assuming a priori what the metric g^\mu\nu in curved space is before solving Einstein's equations.) In the past a number of interesting quantum theories, such as the Lee model and the Pais-Uhlenbeck model, were abandoned because they were thought to have an incurable disease. The symptom of the disease was the appearance of ghost states (states of negative norm). The cause of the disease is that the Hamiltonians for these models were inappropriately treated as if they were Dirac Hermitian. The disease can be cured because the Hamiltonians for these models are PT symmetric, and one can calculate exactly and in closed form the appropriate adjoint operation under which each Hamiltonian is Hermitian. When this is done, one can see immediately that there are no ghost states and that these models are fully acceptable quantum theories. Carl Bender is a Professor of Physics at Washington University in St. Louis. Professor Bender has won numerous awards including the Sloan Fellowship (1972-1977), the M.I.T. Graduate Student Council Teaching Award (1976), a Fulbright Fellowship to the United Kingdom (1995-1996), John Simon Guggenheim Memorial Foundation Fellowship (2003-2004), the Ulam Fellowship, Los Alamos National Laboratory, (2006-2007), the Compton Faculty Achievement Award, Washington University (2007), and Wilfred R. and Ann Lee Konneker Distinguished Professor of Physics (2007). In addition, he is a co-author of one of the most influential texts in applied mathematics: Advanced Mathematical Methods for Scientists and Engineers (Bender Orzag). Printable poster October 9, 2008: David Keyes, Columbia University Attacking the asymptotic algorithmic bottleneck: scalable solvers for scientific simulation Abstract: Many simulations with promise for scientific discovery and technological advance are of multiscale and multiphysics character, and subject to uncertainties of model or data. Asymptotically in mesh resolution, such applications are ultimately bottlenecked by solution algorithms. Simulations based on Eulerian formulations of partial differential equations can be among the first applications to take advantage of petascale capabilities, but not the way most are presently pursued. Weak scaling avoids the fundamental limitation expressed in Amdahl's Law but only optimal implicit formulations can get around another limitation on scaling that is an immediate consequence of Courant-Friedrichs-Lewy stability theory under weak scaling of a PDE. Many PDE-based applications and other lattice-based applications with petascale roadmaps (such as quantum chromodynamics) will likely be forced to adopt optimal implicit solvers. However, even this narrow path to petascale simulation is made treacherous by the imperative of dynamic adaptivity, which drives us to consider algorithms that are less synchronous than those in common use today. After reviewing themes in scalable algorithms at a high level, we focus on some particular advances in the U.S. magnetic fusion energy program and other PDE-based applications enabled by scalable solution algorithms. David E. Keyes is the Fu Foundation Professor of Applied Mathematics in the Department of Applied Physics and Applied Mathematics at Columbia University, and the Chair-designate of the Mathematical and Computer Sciences and Engineering Division at KAUST. With backgrounds in engineering, applied mathematics, and computer science, Keyes works at the algorithmic interface between parallel computing and the numerical analysis of partial differential equations, across a variety of applications. Newton-Krylov-Schwarz parallel implicit methods, introduced in a 1993 paper, are now widely used throughout computational physics and engineering and scale to many thousands of processors. Keyes is currently the Vice President-at-Large of SIAM, and a member of the advisory committees of the Mathematics and Physical Sciences Directorate and the Office of CyberInfrastructure of the NSF. Printable poster October 23, 2008: John Bush, MIT Interfacial Biomechanics
标签: Applied
