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21.
The urban destruction captured by black and white photos of London after the Blitz or bomb-damaged Berlin are emblematic of the desolation brought by modern warfare. Eyal Weizman , Paulo Tavares , Susan Schuppli and Situ Studio describe, though, how the built environment now represents more than a means of violation in conflict, as it has become an important source of evidence bearing witness to the event when international justice is sought. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
22.
Studies of chemically induced porogen decomposition in Porogen Derived Membranes show that substantially complete decomposition of porogen molecules, molecularly dispersed in the polymeric matrix, is attainable. Several hours are required for decomposition by reagents penetrating into the premembrane at ambient. Decomposition rate is determined by characteristics of polymer, porogen, and reagent used, by polymer/porogen weight ratio, by reagent concentration, and by temperature. The concept of decomposition by an internal catalyst was also validated. In addition to direct relevance to the new method of membrane formation, the study provides better understanding of phenomena of general interest, such as transport of small molecules through changing polymeric matrices. © 1992 John Wiley & Sons, Inc. 相似文献
23.
The distractor-ratio effect refers to the finding that search performance in a conjunctive visual search task depends on the relative frequency of two types or subsets of distractors when the total number of items in a display is fixed. Previously, Shen, Reingold, and Pomplun (2000) examined participants' patterns of eye movements in a distractor-ratio paradigm and demonstrated that on any given trial saccadic endpoints were biased towards the smaller subset of distractors and participants flexibly switched between different subsets across trials. The current study explored the boundary conditions of this tendency to flexibly search through a smaller subset of distractors by examining the influence of several manipulations known to modulate search efficiency, including stimulus discriminability (Experiment 1), within-dimension versus cross-dimension conjunction search and distractor heterogeneity (Experiment 2). The results indicated that the flexibility of visual guidance and saccadic bias exemplified by the distractor-ratio effect is a robust phenomenon that mediates search efficiency by adapting to changes in the relative informativeness of stimulus dimensions and features. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
24.
An interactive proof system is calledperfect zero-knowledge if the probability distribution generated by any probabilistic polynomial-time verifier interacting with the prover on input
theoremϕ, can be generated by another probabilistic polynomial-time machine which only getsϕ as input (and interacts with nobody!).
In this paper we present aperfect zero-knowledge proof system for a decision problem which is computationally equivalent to the Discrete Logarithm Problem.
Doing so we provide additional evidence to the belief thatperfect zero-knowledge proof systems exist in a nontrivial manner (i.e., for languages not inBPP). Our results extend to the logarithm problem in any finite Abelian group.
This research was partially supported by the Fund for Basic Research Administered by the Israeli Academy of Sciences and Humanities.
An early version of this paper appeared inAdvances in Cryptology —Crypto 88 (Proceedings), S. Goldwasser (ed.), pp. 57–70, Lecture Notes in Computer Science, vol. 403, Springer-Verlag, Berlin, 1990. 相似文献
25.
Daneman Meredyth; Reingold Eyal M.; Davidson Monica 《Canadian Metallurgical Quarterly》1995,21(4):884
Eye fixation data suggest that readers use orthographic codes rather than phonological codes to activate word meanings. Whereas proofreading data show that readers are less likely to detect homophonic errors (e.g., He was in his silk stocking feat) than nonhomophonic errors (e.g., He was in his silk stocking fate), the eye fixations revealed that readers initially experienced as much difficulty encountering a homophonic error as a nonhomophonic one. However, homophony facilitated the recovery process, thus suggesting that phonology has its influence after lexical access. Exp 1 showed that the findings were consistent whether the error was the lower frequency homophone (stocking feat) or the higher frequency homophone (feet of courage). Exp 2 showed that proofreading responses are unreliable indices of error detection because even when readers fail to make an overt error detection response, their eye fixations reveal that they have detected the error. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
26.
A community-oriented programme for rehabilitation of persons with arthritis is described. It combines an 8-week ambulatory rehabilitation course (including patient education) at a rehabilitation institution, with long-term self-rehabilitation (at patients' homes), supervised by primary-care nurses. Sixty persons (mean age 54; 80% females) with a 13-year average duration of arthritis, were suffering pain, physical limitations, difficulties in social activities, tension and a tendency to depression. They had completed the course and a 12-month self-rehabilitation at home, and were assessed with the Arthritis Impact Measurement Scales (AIMS) questionnaire on admission to the course, at its completion and 1 year thereafter. Assessment upon completion of the course showed improvement in all areas studied. Measurements at follow-up showed that the majority carried out self-rehabilitation activities and preserved the improved functional status. The programme provided a much-needed service to arthritis sufferers living in the community, and promoted both the reorientation of institution-based rehabilitation professionals towards the community and self-rehabilitation and the cooperation between the institution and primary care. 相似文献
27.
We consider the problem of learning DNF formulae in the mistake-bound and the PAC models. We develop a new approach, which is called polynomial explainability, that is shown to be useful for learning some new subclasses of DNF (and CNF) formulae that were not known to be learnable before. Unlike previous learnability results for DNF (and CNF) formulae, these subclasses are not limited in the number of terms or in the number of variables per term; yet, they contain the subclasses of k-DNF and k-term-DNF (and the corresponding classes of CNF) as special cases. We apply our DNF results to the problem of learning visual concepts and obtain learning algorithms for several natural subclasses of visual concepts that appear to have no natural boolean counterpart. On the other hand, we show that learning some other natural subclasses of visual concepts is as hard as learning the class of all DNF formulae. We also consider the robustness of these results under various types of noise.An earlier version of this paper appeared in the Proceedings of the Sixth Annual ACM Workshop on Computational Learning Theory, COLT93.Current address: Department of Computer Science, Technion, Israel. e-mail:eyalk@cs.technion.ac.il 相似文献
28.
We propose constructing provable collision resistant hash functions from expander graphs in which finding cycles is hard.
As examples, we investigate two specific families of optimal expander graphs for provable collision resistant hash function
constructions: the families of Ramanujan graphs constructed by Lubotzky-Phillips-Sarnak and Pizer respectively. When the hash
function is constructed from one of Pizer’s Ramanujan graphs, (the set of supersingular elliptic curves over
with ℓ-isogenies, ℓ a prime different from p), then collision resistance follows from hardness of computing isogenies between supersingular elliptic curves. For the LPS
graphs, the underlying hard problem is a representation problem in group theory. Constructing our hash functions from optimal
expander graphs implies that the outputs closely approximate the uniform distribution. This property is useful for arguing
that the output is indistinguishable from random sequences of bits. We estimate the cost per bit to compute these hash functions,
and we implement our hash function for several members of the Pizer and LPS graph families and give actual timings. 相似文献
29.
Ali A. Badran Ihmad A. Al-Hallaq Imad A. Eyal Salman Mohammad Z. Odat 《Desalination》2005,172(3):227-234
A single-stage, basin-type solar still and a conventional flat-plate collector were connected together in order to studythe effect of augmentation on the still under local conditions. The still inlet was connected to a locally made, fin-tube collector such that its outlet was fed to the still basin instead of the common storage tank. Measurements of various temperatures, solar intensities and distilled water productions were taken for several days at various operating conditions. Several modes of operation were studied: still connected to collector for a 24-h period; still connected only during sunlight hours from 8 am to 5 pm, and still operating alone for a 24-h period. These tests were performed using tap water and saline water as a feed. It was found that the mass of distilled water production using augmentation was increased by 231% in the case of tap water as a feed and by 52% in the case of salt water as a feed. 相似文献
30.
Hybrid nanofibers with different concentrations of multi-walled carbon nanotubes (MWCNTs) in polyacrylonitrile (PAN) were fabricated using the electrospinning technique and subsequently carbonized. The morphology of the fabricated carbon nanofibers (CNFs) at different stages of the carbonization process was characterized by transmission electron microscopy and Raman spectroscopy. The polycrystalline nature of the CNFs was shown, with increasing content of ordered crystalline regions having enhanced orientation with increasing content of MWCNTs. The results indicate that embedded MWCNTs in the PAN nanofibers nucleate the growth of carbon crystals during PAN carbonization. 相似文献