I developed a spectrum synthesis method to investigate the physical properties of hot OB main sequence (MS) stars, which are often rapid rotators. The code realistically simulates the surface conditions of rapidly rotating stars, considering the rotationally-deformed stellar shape and gravity darkening effect. Comparing the synthesized absorption line profiles with the observed spectra of the member stars of 19 young Galactic clusters, I determined the projected rotational velocities of 496 stars. The average surface temperature and gravity for most of these objects were then derived from H$\gamma$ line fits. The polar gravity of each star was estimated as a good indicator of the evolutionary status of the star. The derived parameters show that massive rotators spin down during their MS phase. The He abundance data (measured by fitting the He I lines) also favor the theoretical prediction that rotationally-induced mixing can gradually enrich the surface helium abundance through the MS phase. A quicker spin-down is evident in the lower mass star group where a large portion of helium peculiar stars are found. This correlation implies that strong stellar magnetic fields may exist on the surface of these lower mass stars. The same method is also applied to interferometric observations from the CHARA Array of a nearby rapid rotator, Regulus. By combining results from spectroscopic and interferometric analysis, the shape, space orientation, mass, and surface temperature distribution of Regulus are firmly determined. This analysis provides the first evidence of the gravity darkening phenomenon among stars that are not components of an eclipsing binary system. The surprisingly high luminosity determined for Regulus appears to agree with the theoretical prediction that rapid rotator can become more luminous as rotationally-induced mixing brings fresh hydrogen down to the core. Finally I present an extension of the model that simulates the shape, velocity, and temperature variations of a star experiencing nonradial pulsation. I simulated and analyzed the line profile variations in the spectra of $\epsilon$ Per, a B0.7~III star with strong evidence of nonradial pulsation (NRP). A comparison of the model simulations and observations indicates that the pulsations of $\epsilon$ Per have a corresponding local temperature variation that is out of phase with the radial oscillation (a non-adiabatic phase lag).

Le terme beat deafness désigne une forme d’amusie congénitale spécifique à l’aspect temporel en musique qui a été découverte récemment par l’étude d’un cas unique (Phillips-Silver et al., 2011). L’objectif principal de ce mémoire était d’identifier de nouveaux cas. Nous avons évalué, chez 100 étudiants universitaires, les capacités à percevoir le beat à se synchroniser sur celui-ci. Les capacités de perception ont été évaluées au moyen de deux tests: un test de détection de perturbations rythmiques et un test de classification de courts extraits musicaux en marches et valses. Les capacités de synchronisation ont été évaluées au moyen d’une tâche consistant à taper du doigt sur les temps forts des mêmes marches et valses. Quatre personnes se sont démarquées du groupe par des difficultés de perception et de synchronisation, et sont dès lors considérées comme des nouveaux cas de beat deafness. / Beat deafness is a form of congenital amusia related to time that has been documented through a single case very recently (Phillips-Silver et al., 2011). The main goal of this study was to identify new cases. Toward this goal, we screened for deficits in beat perception and synchronization in a sample of 100 healthy university students. We assessed perception, first with an on-line test in which participants had to detect perturbations in metric structure, then with a task in which participants had to judge whether short piano pieces were marches (binary metrical structure) or waltzes (ternary metrical structure). We assessed synchronization with a finger tapping task in which participants had to tap to the strong beats of the same marches and waltzes. Four participants showed a parallel impairment in both perception and synchronization assessments and are therefore considered as new beat-deaf cases.

This thesis is a theoretical and experimental study of the dynamics of an edge-emitting laser diode (850 nm) with phase-conjugate feedback. The experimental device is designed to see the dynamical range of the laser through the temporal and spectral properties while the feedback rate varies. Phase-conjugate feedback is performed through four-wave mixing in a photorefractive crystal. The propagation time of the laser beam in the external cavity is termed external time delay. Under the effect of the feedback, the system shows a wide dynamical range including chaos and self-pulsing states which characteristic properties are determined by the length of the external cavity. For the first time self-pulsing states at frequencies multiples of the fundamental frequency of the external cavity are evidenced. Simulations carried out based on the commonly-used Lang-Kobayashi laser rate equations provide theoretical confirmations to the experimental observations. The main topics tackled here are chaos crisis and bistability of pulsing solutions, self-pulsing regimes (through their stabilization and destabilization) and the transitions between them, characterization of extreme events of two kinds along with their statistical distribution and delay-induced deterministic coherence resonance of low frequency fluctuations. Beyond the fundamental interest of these results and the many comparisons that can be made with other laser systems, applications in the field of all-optical signal generation and control of chaos are direct consequences of this study.

Mastitis is one of the most common and expensive dairy cattle diseases. Mastitis prevention and management are key factors in herd health and improved milk quality. One objective of this research was to evaluate management solutions to maintain a low somatic cell count, based on survey responses from Kentucky dairy producers. Because hyperkeratosis may increase mastitis incidence, another objective of this research was to examine changes in teat end hyperkeratosis in a herd transitioning from a standard pulsation milking system to an individual quarter pulsation milking system. The last objective of this research was to evaluate technologies that monitored rumination time, neck activity, reticulorumen temperature, and milk yield as potential mastitis detection devices.

Techn. Universiẗat, Diss., 2004--Darmstadt.

No description available.

Made available in DSpace on 2015-05-14T12:11:45Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 633797 bytes, checksum: 1d551e5f29abe8b204fe26a85234d19f (MD5) Previous issue date: 2012-05-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Empiricism and intellectualism are distinct perspectives which, taking as a starting point the modernity with the thought of Rene Descartes and the English empiricists, guide the epistemological statute of various areas of scientific knowledge. In the contemporaneity, such perspectives are observed in areas such as anatomy, physiology, medicine, biology, psychology, among others. The comprehension of the body, which is influenced by the cited perspectives, often suffers from a reductionism which one moment tends to the psychologism, and one another to physicism. An approach which proposes an integral understanding of the body needs to take into account the various and complex aspects which compose it. The thought of Maurice Merleau-Ponty and of Sigmund Freud allows a reading of the body as a live and pulsatory instance which resists to the pretension of an objective definition of the body. The subjectivity which permeates all the corporal parts and mechanisms, as well as the pulsional forces which act on them, subvert all and any pretension of a reductionist framework, and impose on the corporeity a living and amazing character. / Empirismo e intelectualismo são perspectivas distintas que, sobretudo a partir da modernidade com o pensamento de Rene Descartes e dos empiristas ingleses, norteiam o estatuto epistemológico de diversas áreas do conhecimento científico. Na contemporaneidade, tais perspectivas se fazem perceber em áreas como a anatomia, fisiologia, medicina, biologia, psicologia, dentre outras. Não raro a compreensão do ser humano que advém dessas perspectivas padece de um reducionismo que hora tende ao psicologismo, hora ao fisicismo. A compreensão e a abordagem do corpo, por exemplo, padecem desse reducionismo. Uma abordagem que pretenda uma compreensão integral do corpo carece levar em conta os diversos e complexos aspectos que o compõem. O pensamento de Maurice Merleau-Ponty e de Sigmund Freud possibilita uma leitura do corpo como uma instância viva e pulsional que resiste a pretensão de uma definição objetiva do corpo. A subjetividade que permeia todas as partes e mecanismos corporais, bem como as forças pulsionais que agem sobre os mesmos, subvertem toda e qualquer pretensão de enquadramento reducionista, e impõem à corporeidade um caráter vivido e surpreendente.

Magister Scientiae - Msc / This thesis reports the results of a twofold study on the recently proposed phenomenon of ‘stellar pulsations’ in young brown dwarfs by the seminal study of Palla and Baraffe (2005) (PB05, thereafter). The PB05 study presents results of a non-adiabatic linear stability analysis showing that young brown dwarfs should become pulsationally unstable during the deuterium burning phase of their evolution. / South Africa

This master's thesis deals with simulation of vortex structure which is created in the draft tube of Francis turbine, at part load flow conditions. The main objective is to get the most accurate results from the calculations, using the student license of Ansys Fluent 19.1. The results from the calculations are compared with the experiment under the Francis-99 project. Mainlly in terms of dynamic properties of vortex rope – aplitude and frequency of pressure pulsations. Additionaly the time-averaged velocity profiles are compared. I used the test-case provided by NTNU – Norwegian University of Science and Technology under the Francis-99 workshop series.

Cílem této diplomové práce je navrhnout peristaltické čerpadlo pro hemodialýzu s ohledem na minimalizaci tlakových pulzací. Pomocí analytické analýzy je navržen nový koncept redukce tlakových pulzací, který využívá zrychlení k navýšení tlaku v prostoru mezi válečky. Fungování peristaltického čerpadla je simulováno pomocí programu Ansys Fluent pro získání lepší představy o proudění v čerpadle. Souběžně s návrhem nového konceptu bylo navrženo více tradiční čerpadlo, které bylo následně vyrobeno a experimentálně odzkoušeno. Data získaná z experimentu mohou být dále použita pro nový koncept.