Higher order impedance and absorbing boundary conditions

Traditionally, generalized impedance boundary conditions (GIBCs) have been used to model dielectrics and coated surfaces, and absorbing boundary conditions (ABCs) have been used to simulate nonreflecting surfaces. The two types have the same mathematical form and, in most instances, a higher order condition involving higher order field derivatives has a better accuracy. We demonstrate that there is a close connection between the two and this enables us to use a systematic method which is available for generating GIBCs of any desired order to derive new two- and three-dimensional ABCs. The method is applicable to curvilinear/doubly-curved surfaces and examples are given. Finally, curves are presented that quantify the accuracy of two-dimensional ABCs up to the fourth order, and show how higher order ABCs can improve the efficiency of large scale partial differential equation (PDE) solutions     

Computer recognition of unconstrained handwritten numerals

Four independently, developed expert algorithms for recognizing unconstrained handwritten numerals are presented. All have high recognition rates. Different experimental approaches for incorporating these recognition methods into a more powerful system are also presented. The resulting multiple-expert system proves that the consensus of these methods tends to compensate for individual weaknesses, while preserving individual strengths. It is shown that it is possible to reduce the substitution rate to a desired level while maintaining a fairly high recognition rate in the classification of totally unconstrained handwritten ZIP code numerals. If reliability is of the utmost importance, substitutions can be avoided completely (reliability=100%) while retaining a recognition rate above 90%. Results are compared with those for some of the most effective numeral recognition systems found in the literature     

Professionalization,risk transfer,and the effect on gender gap in project management

In this paper, we demonstrate that Project Management (PM) in Information Technologies (IT) sector, despite the claims of autonomy and self-determination at work of creative experts, sets up fairly tight controls through management and the rhetoric of professionalism. The client's position of strength overrides the employer's direct control, transferring a major share of the risk inherent in PM to the IT experts themselves. Ensuing long hours of unplanned and unpaid overtime are the most important obstacle facing women in IT's workforce. This paper is based on a qualitative research conducted on 7 Canadian companies acting in multimedia, information technology (IT) business services and optics–photonics. We have interviewed 88 IT experts, women and men, who talk about their working conditions.     

Quantification of phenolic contents and antioxidant capacity of Atlantic sea cucumber, Cucumaria frondosa

The antioxidant activity (oxygen radical absorbance capacity, ORAC) and total phenols and flavonoids were determined in extracts from digestive tract, gonads, muscles and respiratory apparatus of sea cucumber, Cucumaria frondosa. Total phenols content varied from 22.5 to 236.0 mg of gallic acid equivalents/100 g dw, and flavonoids from 2.9 to 59.8 mg of rutin equivalents/100 g. ORAC values ranged from 140 to 800 μmol of Trolox equivalents/g dw. Among all extracts, best antioxidant potencies were observed in ethyl acetate extracts from digestive tract, and in acetonitrile-rich fractions obtained from mixed extracts using acetonitrile/TFA (trifluoroacetic acid) acidified water on muscles, gonads and respiratory apparatus. The weakest potencies were observed with water extracts from digestive tract and respiratory apparatus, and with water-rich fractions obtained from mixed extraction of gonads and muscles. A significant correlation was observed between ORAC values and total phenol content in extracts and fractions of gonads and muscles, but ORAC and phenols were not correlated in digestive tract and respiratory apparatus extracts. ORAC values were significantly correlated (p < 0.05) with total flavonoids in all extracts. Successive eluates obtained from solid-phase extraction of water-rich fractions using C₁₈ cartridge showed ORAC values (105–500 μmol of TE/g) reaching up to 2.3 times the potency of their parent fractions. Flavonoids are suggested to be mainly responsible for observed activities. Our results provide a first quantitative evaluation of C. frondosa tissues as useful sources of antioxidants for human consumption.     

Une méthode heuristique de dimensionnement de réseaux téléinformatiques

Since the implementation of the first computer networks, a great attention has been given to their topological design, because of the financial aspects of their dimensioning and operating. The high number of possible topological configurations, the discrete character of the link capacity options available in the marketplace, the non- linearity of the cost functions associated with the network topologies, constitute the main factors which make complex this design problem. As a result, only heuristic methods can lead with a reasonable computing effort, to good feasible solutions, but not necessarily optimal. This paper proposes a heuristic method for generating in an economical manner network topologies which satisfy some reliability and quality of service constraints. The implementation of the method has been submitted to a sequence of tests which confirm its robustness and its efficiency according to the quality of solutions provided.     

Solution of a difference equation in diffraction theory

A simple technique is described for solving a class of second-order functional difference equations that occur in diffraction problems involving edges and corners     

A canine ex vivo shunt for isotopic hemocompatibility evaluation of a NHLBI DTB primary reference material and of a IUPAC reference material

Factors determining the thrombogenic response to particular artificial surfaces were investigated ex vivo in a canine shunt model. Methods using radioisotopic tracers made it possible to dynamically monitor the deposition of labelled blood cells and proteins on a NHLBI.DTB primary reference material polydimethylsiloxane (PRM.PDMS) and on a IUPAC reference material polyvinyl chloride (IUPAC.PVC). On the one hand, leukocyte affinity tau s(leu) (number of deposited leukocytes mm-2s-1) was not significantly different between IUPAC.PVC (tau s(leu) = 1.2-2.5) and PRM.PDMS (tau s(leu) = 1.5-3.4) and the fibrinogen adsorption rate varied from 33 to 48.10(-5) micrograms mm-2s-1 for both these materials. On the other hand, platelet affinity tau s(plat) (number of deposited platelets mm-2s-1) was significantly different (p < 0.05) for IUPAC.PVC and PRM.PDMS (tau s(plat)PVC = 683 +/- 200 > tau s(plat)PDMS = 327 +/- 80). Scanning electron micrographs of adherent platelets, red cells and leukocytes after blood contact ex vivo were performed after each experiment. This preliminary work contributes not only to quantify the adsorption of different radiotracers, but also to evaluate the superficial distribution of the labelled biological species on the inner surface of the tested biomaterials.     

Major attenuation of food reward with performance-sparing doses of pimozide in the rat.

48 male Sprague-Dawley rats were trained to leverpress for food or saccharin reward, and then tested 4 successive times under conditions of normal reward, nonreward, or pretreatment with the dopamine receptor blocker, pimozide. Normally rewarded Ss progressively slowed responding within sessions (became satiated) with food reward but not with saccharin reward. Nonrewarded Ss and pimozide-treated Ss responded vigorously at the beginning of sessions, but slowed within sessions and showed reduced willingness to respond across sessions. Normal responding in the 1st session and in the early phases of later sessions rules out significant motor impairment. Pimozide appears to attenuate selectively the rewarding quality of food for hungry rats. (French summary) (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)