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Michal Arbilly Uzi Motro Marcus W. Feldman Arnon Lotem 《Journal of the Royal Society Interface》2011,8(64):1604-1615
In an environment where the availability of resources sought by a forager varies greatly, individual foraging is likely to be associated with a high risk of failure. Foragers that learn where the best sources of food are located are likely to develop risk aversion, causing them to avoid the patches that are in fact the best; the result is sub-optimal behaviour. Yet, foragers living in a group may not only learn by themselves, but also by observing others. Using evolutionary agent-based computer simulations of a social foraging game, we show that in an environment where the most productive resources occur with the lowest probability, socially acquired information is strongly favoured over individual experience. While social learning is usually regarded as beneficial because it filters out maladaptive behaviours, the advantage of social learning in a risky environment stems from the fact that it allows risk aversion to be circumvented and the best food source to be revisited despite repeated failures. Our results demonstrate that the consequences of individual risk aversion may be better understood within a social context and suggest one possible explanation for the strong preference for social information over individual experience often observed in both humans and animals. 相似文献
54.
A method used to take advantage of the computer literacy of incoming students and to motivate and enhance a pair of introductory computer engineering courses is described. To carry electrical engineering students from their initial view of a computer as a terminal which understands Fortran to a solid view of what a computing engine does and how to build one, the authors have found it very effective to include a short, intense section on assembly-language programming. The section emphasizes the connection between high-level language programming constructs and machine architecture. To meet the needs of effective material coverage in a five-week segment of the overall two-quarter course, the enormous VAX instruction set was reduced to what looks rather like a reduced instruction set computer (RISC) instruction set of 16 instructions. The instructions selected force full awareness of the details of machine performance and of dynamic memory access and control. By keeping the tool-set small, there is time to concentrate on data structures, internal representations, connections between the high-level language (HLL) and the assembly language expression thereof, and the hardware structures which must underlie computational activity 相似文献
55.
TEG—a hybrid approach to information extraction 总被引:1,自引:1,他引:1
This paper describes a hybrid statistical and knowledge-based information extraction model, able to extract entities and relations
at the sentence level. The model attempts to retain and improve the high accuracy levels of knowledge-based systems while
drastically reducing the amount of manual labour by relying on statistics drawn from a training corpus. The implementation
of the model, called TEG (trainable extraction grammar), can be adapted to any IE domain by writing a suitable set of rules
in a SCFG (stochastic context-free grammar)-based extraction language and training them using an annotated corpus. The system
does not contain any purely linguistic components, such as PoS tagger or shallow parser, but allows to using external linguistic
components if necessary. We demonstrate the performance of the system on several named entity extraction and relation extraction
tasks. The experiments show that our hybrid approach outperforms both purely statistical and purely knowledge-based systems,
while requiring orders of magnitude less manual rule writing and smaller amounts of training data. We also demonstrate the
robustness of our system under conditions of poor training-data quality.
Ronen Feldman is a senior lecturer at the Mathematics and Computer Science Department of Bar-Ilan University in Israel, and the Director
of the Data Mining Laboratory. He received his B.Sc. in Math, Physics and Computer Science from the Hebrew University, M.Sc.
in Computer Science from Bar-Ilan University, and his Ph.D. in Computer Science from Cornell University in NY. He was an Adjunct
Professor at NYU Stern Business School. He is the founder of ClearForest Corporation, a Boston based company specializing
in development of text mining tools and applications. He has given more than 30 tutorials on next mining and information extraction
and authored numerous papers on these topics. He is currently finishing his book “The Text Mining Handbook” to the published
by Cambridge University Press.
Benjamin Rosenfeld is a research scientist at ClearForest Corporation. He received his B.Sc. in Mathematics and Computer Science from Bar-Ilan
University. He is the co-inventor of the DIAL information extraction language.
Moshe Fresko is finalizing his Ph.D. in Computer Science Department at Bar-Ilan University in Israel. He received his B.Sc. in Computer
Engineering from Bogazici University, Istanbul/Turkey on 1991, and M.Sc. on 1994. He is also an adjunct lecturer at the Computer
Science Department of Bar-Ilan University and functions as the Information-Extraction Group Leader in the Data Mining Laboratory. 相似文献
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de León AG Dirix Y Staedler Y Feldman K Hähner G Caseri WR Smith P 《Applied optics》2000,39(26):4847-4851
Pixelated, multicolor polarizing filters-of potential use in full-color displays-were produced by what we believe to be a novel method, i.e., masked evaporation of silver and gold onto glass substrates partially covered with separated sub-micrometer-wide strips of oriented poly(tetrafluoroethylene) (PTFE), prepared by friction deposition. The evaporated metal films preferentially nucleated at the glass surface and, consequently, formed parallel arrays in between the PTFE strips. The structures thus produced feature a strong angle-dependent absorption of polarized visible light, allowing for optical switching between red and blue and between green and yellow. 相似文献
58.
Lee D. Johnson A.M. Zucker J.E. Burrus C.A. Feldman R.D. Austin R.F. 《Photonics Technology Letters, IEEE》1992,4(9):949-951
Low-lasing-threshold quasi-continuous optically pumped II-VI quantum-well lasers were operated well above room temperature at 620 nm. This result shows promise for high-repetition-rate, short-pulse generation by direct modulation of the injection current and also CW operation of future wide-gap II-VI diode lasers above room temperature 相似文献
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PM Kirshbom AR Kherani MW Onaitis JM Feldman DS Tyler 《Canadian Metallurgical Quarterly》1998,124(6):1063-1070
The purpose of this study was to analyze our results of surgical treatment of arthrogryposis of the elbow and to compare our tendon transfer results using range of motion (ROM) criteria versus functional use criteria. Eighteen tendon transfers for elbow flexion in 14 children with arthrogryposis with an average follow-up period of 4 years (range, 1-14 years) and 6 elbow capsulotomies with triceps lengthening in 6 children with arthrogryposis with an average follow-up period of 5 years (range, 2-9 years) were evaluated. Each child was assessed by a questionnaire regarding functional use of the upper extremity, physical examination of ROM and strength, and a videotaped activities of daily living evaluation. Tendon transfer results were classified and compared using 2 methods of evaluation: postoperative strength and ROM and effective functional use of the tendon transfer to perform activities of daily living. The 6 elbow capsulotomies improved from an average preoperative arc of 17 degrees of motion (average extension, -2 degrees; average flexion, 19 degrees) to an average final follow-up arc of 67 degrees (average extension, -25 degrees; average flexion, 92 degrees). The 18 tendon transfers evaluated by strength and ROM criteria showed 9 triceps to biceps transfers in 9 arms (7 good, 1 fair, and 1 poor), 5 pectoralis to biceps transfers in 4 arms (1 good, 3 fair, and 1 poor), and 4 latissimus dorsi to biceps transfers in 3 arms (2 good and 2 fair). Evaluation by functional use criteria gave the same result in 13 transfers and downgraded the result in 5; the downgraded results were due to resultant flexion contracture or limited functional use because the transfer was in the nondominant arm. Based on this review, optimal surgical candidates for tendon transfer are children older than 4 years, who have full passive ROM of the elbow in the dominant arm, and at least grade 4 strength of the muscle to be transferred. 相似文献