National Repository of Grey Literature 107 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Zootechnické aspekty inseminace prasnic
Hájek, Petr
The aim of the bachelor thesis is to provide a comprehensive view on the issue of sow insemination and to summarize the current state of knowledge in this area of agricultural production. The bachelor thesis focuses on the description of insemination and on the zootechnical aspects that influence the insemination of sows. As insemination is the most used method of reproduction nowadays, emphasis is placed on the anatomy and physiology of the reproductive apparatus of the sow. Also described are the zootechnical aspects that affect insemination and how these factors influence it. In the last part of the thesis, the insemination itself and its methods of performance are described, discussing the advantages and disadvantages of insemination, including new options such as the semen capsule and its gradual release or a product to influence ovulation.
Modelling of blood flow in a carotid artery with stenoses
Štefek, Martin ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
This bachelor's thesis deals with the analysis of blood flow in a carotid artery with stenoses in the area of the bifurcation. The current state of knowledge is presented in the theoretical part. As part of the practical part of the work, several 2D models of the artery with stenoses of dif-ferent sizes and distances were created. An ideal mesh of finite volumes was created and select-ed. Using the ANSYS Fluent program, basic hemodynamic parameters such as flow velocity, wall shear stress, pressure and fractional flow reserve (FFR) were evaluated for stationary flow. A time step was determined for the transient flow, and then the flow speed and shear stress on the walls at points were evaluated as a function of time.
Computational modelling of the influence of stenoses on blood flow in the carotid artery
Lukáš, Petr ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
This diploma thesis deals with blood flow in carotid artery with tandem double stenosis. In the first part there is described cardiovascular system with emphasis on blood and arteries. In the practical part, geometric models of the carotid artery with 30% and 70% stenosis, as well as a model without stenosis, are created. The second stenosis is not included in the model of geometry but modeled using Windkessel effect. Blood is modeled as a non-Newtonian fluid using the Carreau model. After the calculations, the blood flow and arterial wall stress are evaluated, and the results are compared among the different geometry models. Critical values of shear stress, TAWSS, OSI, and FFR, as well as the mass flow rate in the internal carotid artery, are assessed.
Analysis of a Voice Propagation around the Human Body
Zelinka, Martin ; Švancara, Pavel (referee) ; Hájek, Petr (advisor)
The main objective of this thesis is to create a suitable realistic 3D model of the human body using photogrammetry and then to perform harmonic acoustic analysis in order to determine the reflection surfaces on the human body and the values of acoustic pressure with its level in the production of the human voice. The result of this work is supported by a search of anatomy and physiology of the vocal tract including models describing the propagation of the human voice in the vocal tract and, last but not least, by comparing the obtained results with previous works.
The impact of freezing of arterial tissue on its stress-strain response
Horák, František ; Hájek, Petr (referee) ; Hrubanová, Anna (advisor)
This bachelor thesis deals with freezing of the arterial tissue at -20 °C and its impact on mechanical properties of artery. The introductory part focuses on basic medical terms related to the issue followed by presentation of scientific publications dealing with artery tissue freezing. The attention is mainly paid to measurements and evaluation of results. The main part of the thesis contains description of the methodology of biaxial tensile test of porcine artery tissue with process of measuring the artery’s Young's modulus. Statistical analysis is used to determine the impact of freezing on mechanical properties of the artery. Description of limitations of this experiment is also included.
Inverse modelling of stresses in deformed configuration of left ventricle
Zajac, Radim ; Hájek, Petr (referee) ; Vaverka, Jiří (advisor)
The bachelor thesis deals with the development of a FEM model of the left ventricle from a freely available stl model obtained from magnetic resonance images and the modification of this model to make it usable for calculation in Ansys MAPDL. The model was defined with isotropic hyperelastic mechanical properties obtained from the actual myocardial properties obtained from tensile tests described in the accompanying literature. A FEM model corresponding to the stress-free state of the left ventricle was obtained and the stress field of the loaded geometry was reconstructed after loading this null geometry. The reconstructed stress field cannot be considered as real due to the idealization of the material and the neglect of the application of pressures on the epicardium of the left ventricle.
Modal Analysis of the Flute
Vojtovič, Adam ; Votava, Tomáš (referee) ; Hájek, Petr (advisor)
The presented bachelor thesis deals with an influence of a fundamental shape and partial sections of flute on frequency of tones. A simple flute is designed and made according to the given formulas. The functionality of the flute is verified by measuring frequencies of each tone. These frequencies are compared with values given analytically and also with values of natural frequencies calculated by finite element method. General information about wind instruments is included in the thesis, too. Besides the clarification of fundamental principles of function of wind instruments, there are also derived fundamental formulas for calculation of natural frequencies of tubes.
Analysis of dental implants in the context of current standards
Šlajs, Ondřej ; Hájek, Petr (referee) ; Marcián, Petr (advisor)
Presented bachelor thesis focuses on geometry production of dental implants from real samples and their stress-strain analysis all in the context of the current standards. In the first part of the thesis research ranging from the basic anatomy to the geometry of implant threads is presented. In the next part, the current standards applicable to dental implants are presented and explained. The last part is focused on the description of the geometry of studied implants and their stress-strain behavior. All this is in context with valid standards.
The biological significance of changes in the vascular wall and atherosclerotic plaque for the development of atherosclerotic disease of the coronary arteries
Horváth, Martin ; Hájek, Petr (advisor) ; Poledne, Rudolf (referee) ; Kovárník, Tomáš (referee)
Acute complications of atherosclerosis are typically caused by arterial occlusion due to acute thrombosis forming over a ruptured vulnerable atherosclerotic plaque (VP). Early identification of such VP prior to their rupture could help prevent these events. At the same time, methods for assessing cardiovascular risk are focused on measures at the population level and are not sensitive and specific enough to assess the risk of individual patients. We therefore focused on the possibilities of in vivo detection of VP using biomarkers and invasive imaging methods. First, we focused on the detection of microRNAs (miRs), which have been investigated in recent years as promising biomarkers for a number of diseases, including atherosclerosis. We determined miR levels using quantitative polymerase chain reaction in peripheral venous blood samples from patients in very early phase of ST-elevation myocardial infarction (STEMI), which served as the closest clinical model of acute VP rupture. The results led to the identification of two miRs (miR-331 and miR-151-3p) that were deregulated in STEMI and could be biomarkers of VP. In the next part of the research, we dealt with the possibilities of invasive imaging of VP using intravascular ultrasound and near- infrared spectroscopy (IVUS and NIRS). We confirmed...
Biomarkers, intravascular ultrasound and near-infrared spectroscopy in the assessment of vulnerable atherosclerotic plaque
Štěchovský, Cyril ; Hájek, Petr (advisor) ; Krajina, Antonín (referee) ; Kaňovský, Jan (referee)
Biomarkers, Intravascular Ultrasound and Near-Infrared Spectroscopy in the Assessment of Vulnerable Atherosclerotic Plaque Abstract The thesis describes pathophysiology of a vulnerable atherosclerotic plaque, detection of the vulnerable plaque in the stenosis of the internal carotid artery (ICA), and optimalization of carotid stenting (CAS) with near-infrared spectroscopy (NIRS) and intravascular ultrasound (IVUS) imaging. NIRS detects lipid core of the vulnerable lipid rich plaque (LRP). We demonstrated safety of NIRS-IVUS imaging during CAS. LRP was detected in one third of ICAs before CAS. Lipid signal was not correlated with plaque morphology (IVUS), biomarkers or clinical variables. CAS caused significant decrease of the lipid signal. Angiography overestimated severity of stenosis of the ICA and vastly underestimated residual stenosis after CAS. Presence of the LRP in the stenosis was neither associated with periprocedural neurological complications of CAS nor long-term adverse cardiovascular events. IVUS identified planimetric features associated with long-term restenosis or stent occlusion. After a median follow-up of 31 months, repeated NIRS-IVUS of the implanted stents showed significant expansion of the stents, diffuse neointimal hyperplasia and further reduction of the lipid signal. We assume,...

National Repository of Grey Literature : 107 records found   1 - 10nextend  jump to record:
See also: similar author names
22 HÁJEK, Pavel
6 Hájek, P.
1 Hájek, Patrik
22 Hájek, Pavel
53 Hájek, Petr
1 Hájek, Přemysl
Interested in being notified about new results for this query?
Subscribe to the RSS feed.