Microstructure of near-infrared pulsed laser sintered titanium samples

The microstructure and material properties of near-infrared pulsed laser sintered titanium have been investigated. Several analyses of the selectively laser sintered titanium powder, using characterisation techniques such as compressive strength, microhardness, energy-dispersive X-ray microanalysis, X-ray diffractometry and scanning electron microscopy analysis, allowed the metallurgical description of the sintering process. Only partial melting in a narrow surface layer took place, whereas most of the material stayed clearly below the melting temperatur

Conserved and divergent functions of Drosophila atonal , amphibian, and mammalian Ath5 genes

Insect and vertebrate eyes differ in their formation, cellular composition, neural connectivity, and visual function. Despite this diversity, Drosophila atonal and its vertebrate Ortholog in the eye, Ath5 , each regulate determination of the first retinal neuron class—R8 photo-receptors and retinal ganglion cells (RGCs)—in their respective organisms. We have performed a cross-species functional comparison of these genes. In ato 1 mutant Drosophila , ectopic Xenopus Ath5 ( Xath5 ) rescues photoreceptor cell development comparably with atonal . In contrast, mouse Ath5 ( Math5 ) induces formation of very few ommatidia, and most of these lack R8 cells. In the developing frog eye, ectopic atonal , like Xath5 , promotes the differentiation RGCs. Despite strong conservation of atonal , Xath5 , and Math5 structure and shared function, other factors must contribute to the species specificity of retinal neuron determination. These observations suggest that the atonal family may occupy a position in a gene hierarchy where differences in gene regulation or function can be correlated with evolutionary diversity of eye development.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72909/1/j.1525-142X.2003.03058.x.pd

Prävalenz von Herzgeräuschen, Aorten- und Pulmonalstenosen bei Zuchtuntersuchungen von Boxern in der Schweiz

Boxer are predisposed to subaortic (SAS) and pulmonic stenosis (PS). To decrease the prevalence, pre-breeding cardiologic exams were performed in the last years. In our study the results of 309 pre-breeding exams of boxers presented between 1999 and 2008 were evaluated retrospectively. The overall prevalence of heart murmurs was 26.5 %. A SAS was diagnosed in 25 (8.1 %) and a PS in 10 (3.3 %) dogs. A combination of both defects was found in 7 (2.3 %) Boxers. Animals with a heart murmur of at least grade 3/6 had a significantly higher peak aortic flow velocity (VmaxAo) than animals without or only soft heart murmurs. Over the study period both the frequency of heart murmurs and diagnosis of SAS and PS decreased

Referee assignment for volleyball championship: A competition between three local search heuristics

We model the problem of assigning referees to matches of volleyball championships as a combinatorial optimization problem. To solve it, we adapt three local search heuristics and study their behavior as a funtion of their parameters. We show the limitations of these algorithms and that the use of refined initialization algorithms and an "endgame" strategy can significantly enhance their efficiency

A prototype tool to schedule and simulate the house refurbishment process

The organization of refurbishment is a complex problem involving both physical and social constraints. Our purpose is to develop a computer aided tool to schedule renovation tasks. This paper presents an original methodology to generate and schedule renovation tasks according to constructional constraints and following a given strategy corresponding to organizational choices of planners. This research was supported by the Swiss National Science Foundation (FNRS

Numerical modeling in induction heating for axisymmetric geometries

This paper deals with numerical simulation of induction heating for axisymmetric geometries. A mathematical model is presented, together with a numerical scheme based on the Finite Element Method. A numerical simulation code was implemented using the model presented in this paper. A comparison between results given by the code and experimental measurements is provided

Numerical modelling of induction heating of long workpieces

International audienceWe consider in this paper an induction heatingprocess. A mathematical model is presented, together with numericalmethods used in order to describe the magnetic field,as well as the temperature field evolution. Experimental measurementswere performed in order to validate the numericalsimulation results. A comparison is presented for both ferromagneticand non-ferromagnetic materials. An error discussionis provided

Modeling of near infrared pulsed laser sintering of metallic powders

Using pulsed near infrared laser radiation for selective laser sintering bears several advantages compared to cw sintering such as low required average power, less residual heat and improved lateral precision. By adapting the pulse length (and thus the heat diffusion length during the pulse) to the grain size of the used metal powder, the laser pulse energy can mainly be deposited in the skin of the powder particles where heating and melting is obtained, whereas the centers of the grains remain at much lower temperature and act as heat sinks after consolidation. The model described here was numerically implemented and experimentally tested with a pulsed Nd:YAG laser on titanium powder. The results of the model predictions and the performed experiments are in good agreement