Model Study of Ultrasound Effects on Fetal Development

Výrazný rozvoj ultrazvukové techniky je úzce svázán se zvyšováním výstupního výkonu ultrazvukových sond. Účinky ultrazvukového vlnění mohou za určitých podmínek nepříznivě ovlivnit vývoj plodu. Současné studie, které se zabývají modelováním účinků na biologickou tkáň jsou založeny na simulaci pole elementárních měničů. Hodnocené tepelné účinky jsou obvykle určovány jednorozměrně v ose měniče. Vytvořením flexibilního modelu diagnostických systémů je možné simulovat vyzařování různých typů sond a modelovat oteplení tkání v závislosti na typu apertury a buzení. Podle náhradních elektromechanických modelů byla určena impulsní odezva piezoelektrických měničů. Ta je využita pro simulaci třírozměrného rozložení akustického tlaku a intenzity ultrazvuku. Jsou modelovány možnosti fázování a dynamické fokusace svazku na základě optimalizace řady měničů. Pro určení tepelných účinků je simulován vrstvený 3D model mateřské tkáně a plodu. Uvažovány jsou hraniční případy ozvučení v lékařské prenatální ultrasonografii a výsledky byly srovnány s měřením akustických polí několika diagnostických sond. Měření oteplení bylo provedeno ve tkáňovém fantomu. Výsledky práce poukazují na možná ohrožení plodu během vyšetření současnými diagnostickými sondami a na jejich základě jsou odvozena praktická doporučení.The progress in ultrasound techniques goes hand in hand with increasing of diagnostic machine acoustic outputs. Ultrasound biological effects can adversely influence the development of human fetus. Recent studies of thermal effect on biological tissues are usually based on simulation of simple ultrasound transducers. The aim of this work is to build a flexible model of diagnostic system to simulate temperature increase during fetal development. Different types of ultrasound probes were used for generation of acoustic field with simulated piezoelectric element properties. Optimized linear and phased arrays were modeled with dynamic beam steering and focus. Computer simulations were concentrated on extreme conditions in obstetric ultrasonography and 3D tissue model was compared with real ultrasound probes measurements. To detect temperature increase, the bone tissue phantom was used. Results point out potential risks for fetus with diagnostic ultrasound probes. Based on the results of this work, practical recommendations increasing safety of obstetric examinations were drawn.

Leaf-spinning moths (Lepidoptera) feeding on Vaccinium uliginosum L. along an ecological gradient of central European peat bogs

The leaf-spinning moths (Lepidoptera: Tortricidae, Gelechiidae, Chimabachidae and Geometridae) associated with the boreal plant Vaccinium uliginosum L. were investigated in two different peat bogs (Mrtvy luh and Chalupská slat’), both situated in the Sumava Mts., Czech Republic. During four years (1998–2001) of collecting leaf spinnings, 19 species of moths were recorded from both localities. Their occurrence was clearly structured along a distinct ecological (mesoclimatic) gradient. Species closely associated with peat bogs (tyrphobiontic and tyrphophilous taxa) were found to be most abundant in the treeless centres of both peat bogs in comparison with marginal parts. Vaccinium uliginosum is the only food plant of stenotopic boreal moths Pammene luedersiana (Sorhagen) and Athrips pruinosella (Lienig & Zeller) recorded in the Sumava Mts

Geographical variation in food plant selection of Eupithecia gelidata Möschler, 1860 (Lepidoptera, Geometridae)

The relict bog populations of Eupithecia gelidata Möschl. in South Bohemia are obligatorily associated with Ledum palustre L., which is here the dominant shrub, all Salix species being absent. In the subarctic and boreal populations of E. gelidata, altemative food plants are willows (Salix spp.). Under laboratory conditions, larvae of the Bohemian populations can accomplish their development feeding on Salix, but Ledum is clearly preferred. The larvae living on Ledum and Salix are usually differently coloured. Thus, in spite of the different food plants and coloration of the larvae, the species seems to be taxonomically homogeneous

Parasitoids (Hymenoptera) of leaf-spinning moths (Lepidoptera) feeding on Vaccinium uliginosum L. along an ecological gradient in central European peat bogs

Parasitoids of leaf-spinning Lepidoptera associated with two isolated central European peat bogs were investigated. Five families of parasitoid Hymenoptera (Braconidae, lchneumonidae, Eulophidae, Pteromalidae and Encyrtidae) were recorded. Three categories were recognised: (1) primary parasitoids, (2) facultative hyperparasitoids and (3) obligatory hyperparasitoids. Ten species of Braconidae, five species and seven marked morphospecies among lchneumonidae, and three species of Chalcidoidea were identified. Despite of some niche-specific (but less host-specific) parasitoids, all these hymenopterans are likely to be generalists and none of them were confirmed to be habitat and/or host specialists. Unlike their eurytopic (opportunistic tyrphoneutral) parasitoids, the Lepidoptera hosts associated with peat bogs are partially highly stenotopic (tyrphobionts and tyrphophiles). The occurrence of parasitoids compared to their potential hosts was structured along an ecological (mesoclimatic) gradient, so most parasitoids were recorded from margins while stenotopic (narrow habitat adaptation) moths were mostly distributed near the centre of the bog habitat

Apocynin and Diphenyleneiodonium Induce Oxidative Stress and Modulate PI3K/Akt and MAPK/Erk Activity in Mouse Embryonic Stem Cells

Reactive oxygen species (ROS) are important regulators of cellular functions. In embryonic stem cells, ROS are suggested to influence differentiation status. Regulated ROS formation is catalyzed primarily by NADPH-dependent oxidases (NOXs). Apocynin and diphenyleneiodonium are frequently used inhibitors of NOXs; however, both exhibit uncharacterized effects not related to NOXs inhibition. Interestingly, in our model of mouse embryonic stem cells we demonstrate low expression of NOXs. Therefore we aimed to clarify potential side effects of these drugs. Both apocynin and diphenyleneiodonium impaired proliferation of cells. Surprisingly, we observed prooxidant activity of these drugs determined by hydroethidine. Further, we revealed that apocynin inhibits PI3K/Akt pathway with its downstream transcriptional factor Nanog. Opposite to this, apocynin augmented activity of canonical Wnt signaling. On the contrary, diphenyleneiodonium activated both PI3K/Akt and Erk signaling pathways without affecting Wnt. Our data indicates limits and possible unexpected interactions of NOXs inhibitors with intracellular signaling pathways

Cell segmentation methods for label-free contrast microscopy: review and comprehensive comparison

Because of its non-destructive nature, label-free imaging is an important strategy for studying biological processes. However, routine microscopic techniques like phase contrast or DIC suffer from shadow-cast artifacts making automatic segmentation challenging. The aim of this study was to compare the segmentation efficacy of published steps of segmentation work-flow (image reconstruction, foreground segmentation, cell detection (seed-point extraction) and cell (instance) segmentation) on a dataset of the same cells from multiple contrast microscopic modalities

Macroporous bioceramic scaffolds based on tricalcium phosphates reinforced with silica: microstructural, mechanical, and biological evaluation

The positive effect of silica on microstructural, mechanical and biological properties of calcium phosphate scaffolds was investigated in this study. Scaffolds containing 3D interconnected spherical macropores with diameters in the range of 300-770 mu m were prepared by the polymer replica technique. Reinforcement was achieved by incorporating 5 to 20 wt % of colloidal silica into the initial hydroxyapatite (HA) powder. The HA was fully decomposed into alpha and beta-tricalcium phosphate, and silica was transformed into cristobalite at 1200 degrees C. Silica reinforced scaffolds exhibited compressive strength in the range of 0.3 to 30 MPa at the total porosity of 98-40%. At a nominal porosity of 75%, the compressive strength was doubled compared to scaffolds without silica. When immersed into a cultivation medium, the formation of an apatite layer on the surfaces of scaffolds indicated their bioactivity. The supportive effect of the silicon enriched scaffolds was examined using three different types of cells (human adipose-derived stromal cells, L929, and ARPE-19 cells). The cells firmly adhered to the surfaces of composite scaffolds with no sign of induced cell death. Scaffolds were non-cytotoxic and had good biocompatibility in vitro. They are promising candidates for therapeutic applications in regenerative medicine

SOCIETY AND THE CHURCH IN THE FORMER WESTERN ROMAN EMPIRE IN THE 5TH TO THE 7TH CENTURY

The thesis titled "Society and Church within the Territory of the Former Western Roman Empire in the 5th to 7th century AD" focuses on relations between the society and the church, specifically within territories which, at the given period, formed the Western Roman Empire (5th century AD) and its successor states (6th to 7th century AD). The given period was chosen as it marked a turning point in the relations between the state, or the society, and the church; the further development in Europe, not limited to religion, stems from this period. The 5th century represents a sort of a prologue to the dramatic and turbulent 6th century, while the 7th century is an afterpiece during which the details of the further direction and development of the Catholic Church were refined. The aim of my thesis was to confirm or disconfirm the hypotheses that Christianity (the church) did not accelerate the fall of the Western Roman Empire or that it did not significantly contribute to it, that it was not a bearer of progress as it did not improve the general conditions, and that the church had the character of any religion serving power and was not unique in any way at the time. Attention is paid initially to political and economic situation, which is followed by the study of the relationships between the church and the..

The Possibilities of Aluminium Alloys Refining

Import 23/08/2017Bakalářská práce je zaměřena na teoretický rozbor možností rafinací hliníkových slitin. Jsou zde rozebrány jednotlivé vlastnosti a chování čistého hliníku, následně pak jeho slitin. Důležitým bodem závěrečné práce je podrobné popsání plynů a vměstků přítomných ve slitinách hliníku. Z důvodu vzniku těchto nečistot je nutné provádět rafinaci, pomocí které je možno tyto nežádoucí látky odstranit. Rafinace a její možnosti využití jsou rozebrány v další části této práce. S rafinací souvisí odplynění a následné měření obsahu plynů v tavenině, nejdůležitější metody jsou uvedeny v závěru práce.The bachelor thesis deals with the theoretical analysis of the possibilities during refining of aluminium alloys. There are analyzed particular characteristics and behaviour of the pure aluminium and aluminium alloys. A very important point of this final thesis is detailed description of gases and impurities which are contained in aluminium alloys. By the reason of information of these impurities is necessary to perform the refining process by which is possible to remove these undesirable substances. Refining and it's possibilities are analysed in the next part of this thesis. With the refining is connected a process of degassing and subsequent measuring of gas content in the aluminium melt. Most important methods are listed at the end my final thesis.618 - Katedra metalurgie a slévárenstvívelmi dobř