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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
721

Prenatal Pathways to Early Puberty: Testing the Thrifty Phenotype and Fetal Overnutrition Hypotheses

Olivia C Robertson (11647522) 08 November 2021 (has links)
<p>This thesis outlined a novel operationalization and extension of the thrifty phenotype and fetal overnutrition hypotheses, two evolutionary developmental hypotheses stemming from the developmental origins of health and disease perspective, for developmental pathways from prenatal risk through child growth to early puberty. Support has accumulated for both, but previous studies have not clearly determined which hypothesis better predicts early puberty. Using the Fragile Families and Child Wellbeing Study (<i>n</i>=4898), the thrifty phenotype and fetal overnutrition pathways were tested against each other, separately by sex, and race/ethnicity for adrenal, and gonadal pubertal markers. Results indicated that in general, both hypotheses were supported. Contrary to hypotheses, the thrifty phenotype pathway did not predict perceived pubertal timing better in boys and the fetal overnutrition pathway did not predict perceived pubertal timing best in girls. Instead, both pathways predicted puberty equally well between girls and boys and the fetal overnutrition pathway stemming from maternal gestational weight gain was stronger than the pre-pregnancy BMI pathway. Individual paths of the hypothesized pathways were generally supported when analyzed by race/ethnicity group separately, but support for the entire pathways were sparse. Implications of this work are that pubertal timing may be similarly programmed by restrictive and overnutrition prenatal risks, both should be prioritized, and that interventions for maternal gestational weight should be prioritized over interventions for pre-pregnancy BMI for reducing rates of early puberty. </p>
722

Elektronicky řízená dělící hlava / Electronically controled index head

Holík, Pavel January 2009 (has links)
Summary of structure design possibility. Proposal of structure design. Hardware proposal. Software proposal. Gearing calculation.
723

Variabilní geometrie sacích a výfukových portů Wankelova motoru / Variable geometry of intake and exhaust ports of Wankel engine

Krejčí, Tomáš January 2010 (has links)
The purpose of this thesis is to design the key parameters of the high-powered Walkel engine and to design a chamber side on the base of computed parameters so that it enables variable change of the intake and exhaust port geometry. Consequently, to carry out a flow simulation in both ports in designed chamber side in order to find out its flow character and geometry change reaction.
724

Návrh jednotné koncepce teleskopů manipulátorů přepravek pro zakladače typu Navette a SMC / Unified Design of Box Gripper Telescopes for Navette and SMC Storage Machines

Sojka, Michal January 2016 (has links)
The aim of this diploma thesis is unified design of box gripper telescopes for Navette and SMC storage machines. The work contains technical report and drawings documentation. The first part of technical report is aim to research of similar constructions used in the world. Followed by own construction solution, including needed calculation. At the final part of work was created a tolerance analysis of new telescope. The drawings documentation contains assembly and subassembly drawings.
725

Ventilový rozvod přeplňovaného motoru formule Student / Valve Train for Turbocharged Formula Student Engine

Buchta, Martin January 2016 (has links)
This diploma thesis deals with valve train design of turbocharged engine used in Formula Student category race car. Based on thermodynamic model, a proper valve timing was chosen to achieve maximum power at high engine speed. A kinematic model was used to compute final cam profiles and CAD model was created.
726

Temporal Processing In The Amygdalo-Prefronto-Dorsostriatal Network In Rats / Traitement de l'information temporelle dans le réseau amygdalo-préfronto-dorsostriatal chez le rat

Tallot, Lucille 18 December 2015 (has links)
Le temps est une dimension essentielle de la vie. Il est nécessaire, entre autres, pour réaliser des mouvements coordonnés, pour communiquer, mais aussi dans la prise de décisions. L’objectif principal de cette thèse était de caractériser le rôle d’un réseau amygdalo-préfronto-dorsostriatal dans la mémorisation et l’encodage du temps chez le rat. Dans un premier temps, nous avons décrit le comportement temporel du rat lors d’une tâche de suppression conditionnée (i.e. la suppression d’une réponse instrumentale d’appui sur levier par la présentation d’un son associé à un stimulus aversif), démontrant ainsi un contrôle temporel fin du comportement dans une situation Pavlovienne aversive. Dans un deuxième temps, nous avons analysé les potentiels de champs locaux (analyse fréquentielle des activités oscillatoires) de notre réseau d’intérêt au début d’un apprentissage associatif et après surentraînement dans la tâche de suppression conditionnée. En effet, le comportement temporel moteur nécessite un grand nombre de séances d’apprentissage pour devenir optimal, alors que l’apprentissage temporel est, lui, très rapide. Cette étude nous a permis de caractériser des corrélats neuronaux temporels au sein de ce réseau, que ce soit au niveau des structures individuelles ou au niveau de l’interaction entre ces structures. De plus, ces corrélats neuronaux sont modifiés selon le niveau d’entraînement des animaux. Enfin, dans une troisième étude, nous avons démontré que des ratons juvéniles (pré-sevrage), qui présentent un cortex préfrontal ainsi qu’un striatum dorsal immatures, peuvent mémoriser et différencier des intervalles de temps, ouvrant donc la question sur le rôle de ce réseau dans l’apprentissage temporel au cours du développement. / Time is an essential dimension of life. It is necessary for coordinating movement, for communication, but also for decision-making. The principal goal of this work was to characterize the role of an amygdalo-prefronto-dorsostriatal network in the memorization and encoding of time in a rat model. Firstly, we described temporal behavior in a conditioned suppression task (i.e. the suppression of an instrumental lever-pressing response for food by the presentation of a cue associated with an aversive event), therefore showing a precise temporal control in Pavlovian aversive conditioning. Secondly, we measured local field potentials in our network of interest at the beginning of associative learning and after overtraining in the conditioned suppression task. In effect, motor temporal behavior requires a large number of training sessions to become optimum, but temporal learning happens very early in training. This study allowed us to characterize, using frequency analysis of oscillatory activities, neuronal correlates of time in this network both at the level of individual structures, but also in their interactions. Interestingly, these neural correlates were modified by the level of training. Finally, we demonstrated that juvenile rats (pre-weaning), with an immature prefrontal cortex and dorsal striatum, can memorize and discriminate temporal intervals, raising questions on the role of this amygdalo-prefronto-dorsostriatal network in temporal learning during development.
727

Follow-up and dynamical analysis of Kepler targets with transit timing variations

Freudenthal, Jantje 01 November 2019 (has links)
No description available.
728

Instruction Timing Analysis for Linux/x86-based Embedded and Desktop Systems

John, Tobias 19 October 2005 (has links)
Real-time aspects are becoming more important in standard desktop PC environments and x86 based processors are being utilized in embedded systems more often. While these processors were not created for use in hard real time systems, they are fast and inexpensive and can be used if it is possible to determine the worst case execution time. Information on CPU caches (L1, L2) and branch prediction architecture is necessary to simulate best and worst cases in execution timing, but is often not detailed enough and sometimes not published at all. This document describes how the underlying hardware can be analysed to obtain this information.
729

Robustness Mechanisms of Temporal Cell-Fate Progression in C. Elegans

Ilbay, Orkan 16 December 2019 (has links)
Robustness is a ubiquitous property of biological systems, however, underlying mechanisms that help reinforce the optimal phenotypes despite environmental or physiological perturbations are poorly understood. C. elegans development consists of four larval stages (L1-L4) and well-characterized invariant cell lineages, within which the heterochronic pathway controls the order and timing of cell-fates. Environmental or physiological stress signals can slow or temporarily halt larval stage progression; remarkably, however, temporal cell-fate progression remains unaffected. We show that two widely conserved signaling pathways, insulin and TGF- β, that regulate C. elegans larval stage progression in response to starvation and crowding, respectively, also regulate a rewiring of the heterochronic pathway so that cell-fates remain temporally anchored to appropriate larval stages. This rewiring is mediated by the nuclear hormone receptor DAF-12, and it involves a shift from the reliance on let-7-family microRNAs to the reliance on LIN-46 for proper downregulation of the transcription factor, Hunchback-like-1 (HBL-1), which promotes L2 cell-fates and opposes L3 cell-fates. LIN-46 (which is a homolog of bacterial molybdopterin molybdenum transferase (moeA) and human gephyrin) post-translationally inhibits HBL-1 activity. LIN-46 expression is repressed by the RNA-binding protein LIN-28 at the early stages to permit HBL-1 activity and hence the proper execution of L2 cell-fates. Our results indicate that robustness mechanisms of temporal cell-fate progression in C. elegans involves 1) coordinated regulation of temporal cell-fates and larval stage progression and 2) collaboration between translational regulation exerted by microRNAs and post-translational regulation exerted by LIN-46 to coordinate HBL-1 downregulation with stage progression.
730

A distributed, mobile positioning systemfor wireless, handheld devices

Christiansson, Fredrik January 2000 (has links)
This thesis investigates the possibilities of implementing a location awareness mechanism for the so-called lesswire localNavigator. The author claims that it is possible to implement such a mechanism within the given prerequisites and constraints, even though with today’s technology it may not be economically feasible. Due to the lesswire’s constraints: high accuracy (67%), high-resolution (12 m2) and no hardware modification allowed to the mobile device, the suggested scheme uses Time Difference Of Arrival technology (TDOA). The main advantage of TDOA, as stated in this thesis, is the fact that it is almost totally independent of the preferred wireless technology of the mobile device. TDOA technology therefore, can be applied to a wide range of wireless networks (primarily TDMA, CDMA, FDMA – based). A disadvantage of this scheme is the fact that the network infrastructure needs to be extremely well synchronized - which in turn implies higher costs. Depending on how the synchronization problem is solved, the proposed system may well be economically feasible in the near future.

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