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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.
91

Měření vrstvy nervových vláken sítnice u pacientů s Alzheimerovou chorobou / Retinal nerve fiber layer measurement in patients with Alzheimer's disease

Kasl, Zdeněk January 2017 (has links)
Retinal nerve fiber layer measurement in patients with Alzheimer's disease The current ophthalmologist's possibilities in diagnostics of Alzheimer's disease Alzheimer disease (AD) is the most common cause of dementia syndrome and mild cognitive impairment. To enroll the disease most securely there are used so called biomarkers using evidence of changed brain metabolism by pozitron emission tomography (PET) and in cerebrospinal fluid or the brain's structure magnetic resonance imaging (MRI). These methods are expensive, organisationally and temporally challenging and burdening for the patients. According to that reasons we are still seeking for alternative attitudes suitable for early diagnosis. The evaluation of thickness of retinal nerve fiber layer (RNFL) which is well accessible to examination through optical aparatus of the eye could be one of the options. The aim of our work was to present current knowledges about Alzheimer's disease targeting relations of Alzheimer's disease and an ophthalmological finding. In the next part of this paper we introduce the retinal nerve fiber layer measurement by optical coherence tomography (OCT) as a potential diagnostics method by screening of patients with Alzheimer's disease and to present our results measured in our cohort of patients. The studied cohort...
92

Genetická a hormonální regulace dětského růstu / Genetic and Hormonal Regulation of Children's Growth

Vosáhlo, Jan January 2014 (has links)
Genetic and Hormonal Regulation of Children's Growth MUDr. Jan Vosáhlo Abstract Growth in childhood is a complex process of changing the body, which can be disrupted by various illnesses including endocrine disorders, particularly growth hormone deficiency. Tumors or other processes affecting hypothalamic-pituitary area can be a postnatal cause of GHD; prenatal causes include 1) developmental disorders of the pituitary as part of complex syndromes, 2) developmental disorders of the pituitary due to defects in regulatory genes and 3) defects in genes involved in the synthesis and secretion of GH. The first topic of the thesis was septo-optic dysplasia - a complex syndrome involving optic nerve hypoplasia, structural brain abnormalities and pituitary dysfunctions. We extensively described phenotype in 11 Czech patients; we observed both complete SOD and incomplete forms variously combining two of the three main components of the syndrome. The cohort then became a part of an international study of 68 patients, in which we studied the phenotype in dependence on the brain morphology. We found correlation between the severity of clinical symptoms and the degree of septum pellucidum abnormities and also a correlation between hippocampus and falx abnormities and neurological symptoms. As the second topic we studied...
93

Sledování trvanlivosti výztuží z kompozitních materiálů s polymerní matricí a dlouhovláknovou výztuží / Study of durability of FRP reinforcements

Dipold, Václav January 2016 (has links)
This thesis deals with monitoring the durability of FRP reinforcement in different types of environments which cause degradation. The theoretical part of the thesis describes reinforcing fibers, matrix materials, manufacturing technology of composite reinforcements by pultrusion and durability of FRP materials in environmental degradation. In the experimental part of this thesis was carried storing samples reinforcements in alkaline environment with various temperatures. As suitable were selected temperatures of 20 °C, 40 °C and 60 °C. Subsequently are described changes in physical properties of the reinforcements and tracking optical microscope.
94

Plazmonické biosenzory založené na zvýšené optické transmisi / Plasmonic biosensors based on extraordinary optical transmission

Dršata, Martin January 2017 (has links)
Tato diplomová práce se zabývá rigorózními simulacemi plazmonických biosenzorů založených na jevu zvýšené optické transmise. První část je věnována popisu fyzikálních jevů a poznatků, které tvoří základ pro studium vlastností plazmonických senzorů, a popisu výpočetní metody konečných prvků v časové oblasti, která je využita v této práci. Vlastní výsledky jsou uvedeny v další části, která se zabývá výzkumem citlivosti, rozlišení a dalších charakteristik zvoleného typu plazmonického sensoru, tvořeného sítí kruhových nanoděr v tenké zlaté vrstvě na substrátě nitridu křemíku, v závislosti na řadě jeho geometrických parametrů. Tyto závislosti jsou sledovány ve třech různých případech, a to senzoru umístěného ve vakuu, ponořeného ve vodě a v případě kdy je na zlatém povrchu umístěna tenká dielektrická vrstva, která reprezentuje přítomnost biomolekul uchycených na povrchu senzoru.
95

Optimalizace služeb v optických přístupových sítích FTTx / Services Optimization in FTTx Optical Access Networks

Horváth, Tomáš January 2017 (has links)
This thesis deals with an optimization of Triple play services and security in optical access networks. The first chapter provides theory basics which are necessary for results evaluation. The second chapter describes optical access networks with their parameters such as transmission speed, split ratio, line code, bit error rate etc. defined by ITU. Next chapter summaries the current state in optical networks construction field according to the European Union developing plan. The practical part of this thesis is divided into several subchapters. The significant part of the thesis is dedicated to the security of passive optical networks and design of proper security model for current networks. For this purpose, the unique parameter time propagation Tprop, with the novel security model was developed. Next part of the thesis provides an analysis of control traffic and data traffic in the gigabit passive optical networks. For a novel algorithm in activation process in gigabit passive optical networks the measurement results were used. The novel algorithm decreases the total time needed for this process. The last but one subchapter deals with an ILP model for Triple Play services. The last subchapter contains the own implementation of the transmission converge layer in VPIphotonics simulation tool.
96

Rozdíly v chování řidiče při jízdě přes přechod pro chodce v noci a ve dne / Differences in the Driver's Behavior when Driving through a Pedestrian Crossing at Night and in the Daytime

Vlasák, Jaroslav January 2017 (has links)
The theoretical part of the diploma thesis focuses on the drivers reacting on a pedestrian crossing during the day and the night. A particular attention is paid to all the factors that can influence drivers' behaviour while driving through a pedestrian crossing. The influence of the behaviour by these factors often causes car accidents with pedestrians. One of the basic techniques is to analyze the behavior of the driver in the optical perception of stimuli that affect the optical response. Eyetracker is used to measure the optical responses. This device monitors changes of the angle of a driver's view, navigation of a driver and the driver's reaction on different stimuli while driving. The practical part of the thesis deals with an analysis of the drivers' behaviour while driving through a pedestrian crossing during the day and during the night. Twelve drivers took part in the day measurement of driving through the pedestrian crossing in Brno. Night measurement was taken place in Břeclav and Lednice with the attendance of seven drivers. During the ride are monitored the optical reactions of drivers on various impulses with the use of a special device Eyetracker.
97

Elastohydrodynamic Film Study under Impact Loading and Lateral Vibrations / Elastohydrodynamic Film Study under Impact Loading and Lateral Vibrations

Frýza, Josef January 2018 (has links)
Disertační práce se zabývá chováním a odezvou elastohydrodynamického (EHD) mazacího filmu za neustálených provozních podmínek. V úvodní části práce jsou shrnuty poznatky z oblasti EHD mazání; od jeho historie, přes základní mechanismy mazání a používané experimentální metody, až po nedávno publikované studie zaměřené na transientní podmínky. Hlavním cílem práce bylo experimentálně objasnit vliv provozních parametrů a reologických vlastností maziv na chování mazacího filmu v bodovém kontaktu při jeho nárazovém zatěžování a vystavení příčným vibracím. Za tímto účelem byla vyvinuta laboratorní zařízení umožňující měření rozložení mazacího filmu a tření za kontrolovaných nestacionárních podmínek. Experimenty odhalili zásadní roli přibližovacích a zatěžovacích rychlostí na formování stlačených mazacích filmů při nárazovém zatěžování. Výsledky byly srovnávány s nedávným teoretickým řešením. Bylo ukázáno na jeho nedostatky, jež byly následně odstraněny implementací empirických vztahů zohledňujících reologii maziv. V případě příčných vibrací byly nalezeny hranice selhání mazacího filmu a určeny vztahy popisující vliv příčných vibrací na centrální tloušťku filmu a její fluktuace jednotně pro všechny maziva. Závěrečná část práce poskytuje nový pohled na reologii maziv pomocí inovativního přístupu měření třecích reakcí maziva současně ve dvou směrech kontaktu za podmínek příčných vibrací. Tyto původní výsledky rozšiřují pochopení mechanizmů EHD mazání a mohou být použity k dokonalejším návrhům strojů, a vylepšit tak jejich účinnost, spolehlivost a životnost.
98

Podélné indexové struktury v optických vláknech / Longitudinal index structures in optical fibers

Polreich, Štěpán January 2018 (has links)
This thesis describes basic concepts, principles and properties of optical fibers. Considerable part is devoted to fiber gratings that are created by a change in the refractive index in the optical fiber core. In this work is described description, principle, method od production and distribution of gratings on Bragg gratings, gratings with long period and chirped gratings. In this thesis are also presented different types of lasers and their advantages over other lasers. A large part deals with the description of the femtosecond laser, with which the structures will be later made into the material. In addition, the laser modes are differentiated, this is a mode of micro-machining and modification or a change in refractive index of the material. The last part deals with change the refractive index in planar technology, the creation of a groove for fastening the fiber and attempts to write the gratings into the optical fiber. Created fiber sensor are tested for temperature and tensile changes. Finally, the practical use of sensors made by femtosecond laser and the advantages over UV laser and phase mask techniques are presented.
99

Napájecí zdroj Power-Over-Fiber / Power-Over-Fiber power supply

Kos, David January 2018 (has links)
This thesis deals with the possibilities of energy transmission by optical fiber for the purpose of powering of electronic systems. It comprises issues of electrical energy conversion to optical energy, coupling the power into the optical fiber, coupling between fiber and opto-electric transducer, conversion of optical energy to electrical energy, and transformation on required voltage levels. The principles of such Power-Over-Fiber are discussed in the first part of the work. Various technologies for the implementation of key system parts and their effectivity are discussed. In the next part, several Power-Over-Fiber commercial devices are compared. Subsequently, systems for Power-Over-Fiber experimental implementations are proposed. They are based on the utilization of semiconductor laser, multimode fiber, photovoltaic cell and related electronic circuits. The final part of the thesis deals with the construction of experimental systems and measurement of parameters of transmitted power and efficiency.
100

Vliv složení synoviální kapaliny a topografie třecích povrchů na mazání kloubních náhrad / Effect of synovial fluid composition and surface topography modification on lubrication of joint replacements

Hekrle, Pavel January 2018 (has links)
The main objective of this diploma thesis is to determine the influence of synovial fluid compodition and the influence of surface microtextures on lubrication of hip join replacements. For all experiments, hip joint simulator based on the pendulum principle was utilized. Metal heads (CoCrMo) manufactured by B Braun company and and tailor made acetabular cups from optical glass were used as contact couples. Acetabulum dimensions were fabricated according to dimensions of real implants. Experiments with surface microtextures simulated walking cycle for 210 s and development of lubrication film over time was observed.Results have shown that all types of tested structures improved lubrication of contact area, where the best results were obtained for square and triangle shapes respectively. Second set of experiments was based on the fact, that the composition of synovial fluid of healthy people differs from the composition of patients with various stages of osteoarthritis. Therefore, experiments with different model fluids were compared, which in their composition correspond to different groups of patients. For the model fluid that corresponds to the largest number of cases, experiments with individual components and combinations thereof were subsequently performed to provide a more detailed description of how these components affect the film-forming mechanism. The results show, that a change in fluid composition of patients with osteoarthritis can have a major negative effect on fluid formation process within the pair.

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