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Operations Used (operations + used)

Distribution by Scientific Domains

Information Science and Computing	40%

Selected Abstracts

A fast triangle to triangle intersection test for collision detection

COMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 5 2006
Oren Tropp
Abstract The triangle-to-triangle intersection test is a basic component of all collision detection data structures and algorithms. This paper presents a fast method for testing whether two triangles embedded in three dimensions intersect. Our technique solves the basic sets of linear equations associated with the problem and exploits the strong relations between these sets to speed up their solution. Moreover, unlike previous techniques, with very little additional cost, the exact intersection coordinates can be determined. Finally, our technique uses general principles that can be applied to similar problems such as rectangle-to-rectangle intersection tests, and generally to problems where several equation sets are strongly related. We show that our algorithm saves about 20% of the mathematical operations used by the best previous triangle-to-triangle intersection algorithm. Our experiments also show that it runs 18.9% faster than the fastest previous algorithm on average for typical scenarios of collision detection (on Pentium 4). Copyright © 2006 John Wiley & Sons, Ltd. [source]

Extraction of Stimulus-Selective Intrinsic Optical Signals From the Cat Visual Cortex

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 6 2009
Midori Nagai Non-member
Abstract Optical imaging based on intrinsic optical signals has been widely utilized in studies on the functional organization of various areas of the brain. Because of the small size of the optical signals and the large amount of background noise that is present, it is critical to be able to separate the stimulus-driven optical change from the background. In this study, we propose a novel method and apply it to the analysis of the orientation preference structure in cat area 17. The three criteria used to determine the activation included the amplitude of the optical change in the optical intensity, the statistical significance level of the change, and the temporal relationship between the optical change and the visual stimulation. In the activated region extracted by the new method, 82.4 ± 8.2% of the cells were electrophysiologically responsive to the stimuli that evoked the optical change. This was significantly higher than the 46.4 ± 7.1% value obtained when the activation region was extracted by the most widely used method, i.e. a differential map between two complementary stimuli, such as orthogonal orientations. Our newly proposed method provides a robust and an effective way to reduce manual operations used in the signal extraction process. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

On weighted P-quantile aggregation

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 3 2008
Jongyun Hao
We consider the problem of aggregating ordinal information with quantitative or qualitative importance based on quantile operations. For a bag ,x1, x2, ,, xn, in real or in (finite) ordinal scales, the quantile operations used in this paper are operating based on the floating position index of xi that is determined by its position on the ordered sequence (x(1), x(2), ,, x(n)), where x(i) is the ith smallest element of the bag ,x1, x2, ,, xn,. We call this type of quantile aggregation as the floating position index-based quantile (p-quantile) aggregation. We study on weighted p-quantile aggregation in real scales and extend the corresponding techniques to p-quantile aggregation of ordinal information with quantitative importance. The aggregated result of the latter is represented by a general ordinal proportional 2-tuple. On basis of the notion of importance transformation (that is modified from Yager), we investigate p-quantile aggregation of ordinal information with qualitative importance. Then, we use p-quantile aggregation to define the floating position index-based ordered weighted averaging (P-OWA) aggregation of ordinal information with qualitative importance and apply it to the problem of multicriteria decision making. © 2008 Wiley Periodicals, Inc. [source]

Role of resection and primary anastomosis of the left colon in the presence of peritonitis,

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 11 2000
Dr S. Biondo
Background Classically a primary colonic anastomosis is not performed in the presence of left colonic peritonitis. Recently there has been a trend towards resection and anastomosis in selected patients, but no prospective study concerning the safety of this approach has been published. The objective of this study was to define the role of intraoperative colonic lavage with resection and primary anastomosis (RPA) in left colonic peritonitis, and to evaluate the differences in outcome in patients with diffuse or localized peritonitis. Methods Between January 1994 and December 1998, 127 patients underwent emergency operation for a distal large bowel perforation. RPA was the operation of choice and was performed in 61 patients, 38 with localized and 23 with diffuse peritonitis. Septic shock, faecal peritonitis, immunocompromised status and American society of Anesthesiologists grade IV were contraindications to the one-stage procedure. Alternative operations used in high-risk patients were Hartmann's procedure in 55 patients, subtotal colectomy in eight and colostomy in three. Results There were two deaths (3 per cent) among 61 patients treated by RPA and one (2 per cent) case of clinical anastomotic dehiscence. Overall morbidity was 39 per cent and the overall mean(s.d.) hospital stay was 18(15) days. No statistical differences were observed between patients with localized and diffuse peritonitis treated by RPA. Conclusion RPA may be the operation of choice in selected patients with left colonic diffuse peritonitis. © 2000 British Journal of Surgery Society Ltd [source]

Transformation Series as an Ideographic Character Concept

CLADISTICS, Issue 1 2004
Taran Grant
An ideographic concept of character is indispensable to phylogenetic inference. Hennig proposed that characters be conceptualized as "transformation series", a proposal that is firmly grounded in evolutionary theory and consistent with the method of inferring transformation events as evidence of phylogenetic propinquity. Nevertheless, that concept is usually overlooked or rejected in favor of others based on similarity. Here we explicate Hennig's definition of character as an ideographic concept in the science of phylogenetic systematics. As transformation series, characters are historical individuals akin to species and clades. As such, the related concept of homology refers to a historical identity relation and is not equivalent to or synonymous with synapomorphy. The distinction between primary and secondary homology is dismissed on the grounds that it conflates the concept of homology with the discovery operations used to detect instances of that concept. Although concern for character dependence is generally valid, it is often misplaced, focusing on functional or developmental correlation (both of which are irrelevant in phylogenetic systematics but may be valid in other fields) instead of the historical/transformational independence relevant to phylogenetic inference. As an ideographic science concerned with concrete objects and events (i.e. individuals), intensionally and extensionally defined properties are inconsistent with the individuation of characters for phylogenetic analysis, the utility of properties being limited to communicating results and facilitating future rounds of testing. [source]