spatial regularization
Dotaz
Zobrazit nápovědu
The aim of the study was to describe and depict the spatial arrangement of the colon microcirculatory bed as a whole. Various parts of the large intestine and terminal ileum were harvested from either cadaver or section material or gained peroperatively. Samples were then injected with India ink or methylmetacrylate Mercox resin for microdissection and corrosion casting for scanning electron microscopy. The results showed that extramural vasa recta ramified to form the subserous plexus, some of them passing underneath the colon taeniae. Branches of both short and long vasa recta merged in the colon wall, pierced the muscular layer and spread out as the submucous plexus, which extended throughout the whole intestine without any interruption. The muscular layer received blood via both the centrifugal branches of the submucous plexus and the minor branches sent off by the subserous plexus. The mucosa was supplied by the mucous plexus, which sent capillaries into the walls of intestinal glands. The hexagonal arrangement of the intestinal glands reflected their vascular bed. All three presumptive critical points are only gross anatomical points of no physiological relevance in healthy individuals. Neither microscopic weak points nor regional differences were proven within the wall of the whole large intestine. The corrosion casts showed a huge density of capillaries under the mucosa of the large intestine. A regular hexagonal pattern of the vascular bed on the inner surface was revealed. No microvascular critical point proofs were confirmed and a correlation model to various pathological states was created.
- MeSH
- cévy ultrastruktura MeSH
- dospělí MeSH
- korozní odlévání MeSH
- lidé středního věku MeSH
- lidé MeSH
- mikrocirkulace MeSH
- mikroskopie elektronová rastrovací MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mrtvola MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- střevní sliznice krevní zásobení MeSH
- tlusté střevo krevní zásobení ultrastruktura MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
PURPOSE: The Tofts and the extended Tofts models are the pharmacokinetic models commonly used in dynamic contrast-enhanced MRI (DCE-MRI) perfusion analysis, although they do not provide two important biological markers, namely, the plasma flow and the permeability-surface area product. Estimates of such markers are possible using advanced pharmacokinetic models describing the vascular distribution phase, such as the tissue homogeneity model. However, the disadvantage of the advanced models lies in biased and uncertain estimates, especially when the estimates are computed voxelwise. The goal of this work is to improve the reliability of the estimates by including information from neighboring voxels. THEORY AND METHODS: Information from the neighboring voxels is incorporated in the estimation process through spatial regularization in the form of total variation. The spatial regularization is applied on five maps of perfusion parameters estimated using the tissue homogeneity model. Since the total variation is not differentiable, two proximal techniques of convex optimization are used to solve the problem numerically. RESULTS: The proposed algorithm helps to reduce noise in the estimated perfusion-parameter maps together with improving accuracy of the estimates. These conclusions are proved using a numerical phantom. In addition, experiments on real data show improved spatial consistency and readability of perfusion maps without considerable lowering of the quality of fit. CONCLUSION: The reliability of the DCE-MRI perfusion analysis using the tissue homogeneity model can be improved by employing spatial regularization. The proposed utilization of modern optimization techniques implies only slightly higher computational costs compared to the standard approach without spatial regularization.
- MeSH
- algoritmy MeSH
- fantomy radiodiagnostické MeSH
- glioblastom diagnostické zobrazování MeSH
- kontrastní látky farmakologie MeSH
- krysa rodu rattus MeSH
- magnetická rezonanční tomografie * MeSH
- mozek diagnostické zobrazování MeSH
- nádory mozku diagnostické zobrazování MeSH
- perfuze MeSH
- permeabilita MeSH
- počítačová simulace MeSH
- počítačové zpracování obrazu MeSH
- poměr signál - šum MeSH
- reprodukovatelnost výsledků MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Spatial neglect (SN) impedes functional recovery after stroke, leading to reduced rehabilitation gains and slowed recovery. The objective of the present study was to investigate whether integrating prism adaptation treatment (PAT) into a highly intensive rehabilitation program eliminates the negative impact of spatial neglect on functional and motor recovery. We examined clinical data of the 355 consecutive first-time stroke patients admitted to a sub-acute inpatient neurorehabilitation program that integrated PAT. The 7-item Motor Functional Independence Measure, Berg Balance Scale, and Motor Activity Log were used as main outcome measures. We found that 84 patients (23.7%) had SN, as defined by a positive score on the Catherine Bergego Scale via the Kessler Foundation Neglect Assessment Process (KF-NAP®). Although 71 patients (85%) received PAT, the presence of SN at baseline, regardless of PAT completion, was associated with lower functional independence, higher risk of falls, and a lower functional level of the affected upper limb both at admission and at discharge. The severity of SN was associated with inferior rehabilitation outcomes. Nonetheless, patients with SN who received PAT had similar rehabilitation gains compared to patients without SN. Thus, the present study suggests that integrating PAT in an intensive rehabilitation program will result in improved responses to regular therapies in patients with SN.
- Publikační typ
- časopisecké články MeSH
The development of a soil cover is a dynamic process. Soil cover can be altered within a few decades, which requires updating of the legacy soil maps. Soil erosion is one of the most important processes quickly altering soil cover on agriculture land. Colluvial soils develop in concave parts of the landscape as a consequence of sedimentation of eroded material. Colluvial soils are recognised as important soil units because they are a vast sink of soil organic carbon. Terrain derivatives became an important tool in digital soil mapping and are among the most popular auxiliary data used for quantitative spatial prediction. Prediction success rates are often directly dependent on raster resolution. In our study, we tested how raster resolution (1, 2, 3, 5, 10, 20 and 30 meters) influences spatial prediction of colluvial soils. Terrain derivatives (altitude, slope, plane curvature, topographic position index, LS factor and convergence index) were calculated for the given raster resolutions. Four models were applied (boosted tree, neural network, random forest and Classification/Regression Tree) to spatially predict the soil cover over a 77 ha large study plot. Models training and validation was based on 111 soil profiles surveyed on a regular sampling grid. Moreover, the predicted real extent and shape of the colluvial soil area was examined. In general, no clear trend in the accuracy prediction was found without the given raster resolution range. Higher maximum prediction accuracy for colluvial soil, compared to prediction accuracy of total soil cover of the study plot, can be explained by the choice of terrain derivatives that were best for Colluvial soils differentiation from other soil units. Regarding the character of the predicted Colluvial soils area, maps of 2 to 10 m resolution provided reasonable delineation of the colluvial soil as part of the cover over the study area.
- MeSH
- průzkumy a dotazníky MeSH
- půda chemie MeSH
- teoretické modely * MeSH
- zeměpis MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
We examined whether children's (Grades 2-6) causality beliefs about school performance show similar developmental profiles across 6 distinct sociocultural settings (Los Angeles, n = 657; Tokyo, n = 817; East Berlin, n = 313; West Berlin, n = 517; Moscow, n = 551; Prague, n = 768) with the Means-Ends subscale of the tripartite Control, Agency, and Means-Ends Interview. Although previous research on these same children has shown sizable differences in their self-related agency and control-expectancy beliefs, we found markedly similar developmental patterns in their beliefs about the importance of effort, ability, luck, teachers, and unknown factors as causes of school performance. These regularities in children's implicit theories of school suggest that factors such as cognitive maturation, adaptive self-regulatory processes, and commonalities in educational goals are quite uniform influences in shaping school-related causality beliefs.
- MeSH
- dítě MeSH
- etnicita psychologie MeSH
- interní-externí kontrola * MeSH
- lidé MeSH
- městské obyvatelstvo * MeSH
- rozvoj osobnosti * MeSH
- srovnání kultur * MeSH
- testování osobnosti MeSH
- úspěšnost * MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
- Geografické názvy
- Berlín MeSH
- Česká republika MeSH
- Los Angeles MeSH
- Moskva MeSH
- Tokio MeSH
- MeSH
- diabetes mellitus dietoterapie farmakoterapie MeSH
- dospělí MeSH
- inzulin terapeutické užití MeSH
- lidé MeSH
- městské obyvatelstvo MeSH
- senioři MeSH
- venkovské obyvatelstvo MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- srovnávací studie MeSH
Inspired by local outbreaks of campylobacteriosis in the Czech Republic in 2010 linked to the debate about alleged health risks of the raw milk consumption, a detailed study was carried out. Firstly, scanning was utilised to identify spatio-temporal clusters of the disease from 2008 to 2012. Then a spatial method (geographical profiling originally developed for criminology) served as assessment in selecting fresh-milk vending machines that could have contributed to some of the local campylobacteriosis outbreaks. Even though an area of increased relative risk of the disease was identified in the affected city of České Budějovice during January and February 2010, geoprofiling did not identify any vending machines in the area as the potential source. However, possible sources in some nearby cities were suggested. Overall, 14 high-rate clusters including the localisation of 9% of the vending machines installed in the Czech Republic were found in the period 2008-2012. Although the vending machines are subject to strict hygiene standards and regular testing, a potential link between a small number of them and the spatial distribution of campylobacteriosis has been detected in the Czech Republic. This should be taken into account in public health research of the disease.
- MeSH
- časoprostorová analýza * MeSH
- epidemický výskyt choroby MeSH
- kampylobakterové infekce epidemiologie MeSH
- lidé MeSH
- mléko mikrobiologie MeSH
- potravinářská mikrobiologie MeSH
- prodejní automaty na potraviny * MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika epidemiologie MeSH
Vision or visual perception is a complex function of the visual analyser on all of its levels, i.e. the eye, ocular pathway and brain's visual processing centres, including the association areas. Visual acuity is only one of several parameters of vision. Others are e.g. the visual field, colour perception, contrast sensitivity, adaptation to light and darkness and spatial vision. Even for an experienced ophthalmologist it is very difficult to answer one of the most frequently asked questions of parents of a small child: “How does our child actually see?”
- MeSH
- diagnostické techniky oftalmologické * MeSH
- diagnóza MeSH
- kojenec MeSH
- lidé MeSH
- novorozenec MeSH
- optometrie metody MeSH
- pozorování MeSH
- předškolní dítě MeSH
- retina fyziologie MeSH
- směrnice pro lékařskou praxi jako téma MeSH
- věkové faktory MeSH
- zrak fyziologie MeSH
- zraková ostrost MeSH
- zrakové testy * metody MeSH
- Check Tag
- kojenec MeSH
- lidé MeSH
- novorozenec MeSH
- předškolní dítě MeSH
OBJECTIVE: This paper aims to improve the shortcomings of the extant methodologies for realistic Laplacian (RL) computation, and correct the erroneous claims published in the past. METHODS: We implemented several variants of RL computation methods, using various potential approximation techniques and different regularization approaches. The individual variants of the RL computation were tested using simulations based on a realistic head model computed with the boundary element method (BEM). The results which disagreed with previously published works were further analyzed, and the reasons for the disagreement were identified. RESULTS: We identified the best regularization techniques for the surface potential approximation, and we showed that once these techniques are used there is often little difference between various potential approximations, which is in contrast with previous claims that promoted the radial basis function (RBF) approximation. Further, our analysis shows that the RBF approximation suffers from Runge phenomenon, which cannot be mitigated simultaneously for both deep and shallow sources; therefore, its good performance is guarantied only if a priori knowledge about the source depth is available. CONCLUSIONS: The previously published methodology for RL computation was not optimal. Improvements are possible if the newly suggested approach is used. SIGNIFICANCE: The methodology presented in our paper allows more efficient utilization of the RL, providing a useful tool for processing of high density EEG recordings. Presented techniques allow to achieve high EEG spatial resolution, and avoid unnecessary spatial blurring caused by the problems in the previously published RL methodology.
Inzulín je znám pro svůj periferní účinek na metabolizmus glukózy, tuků a bílkovin. Inzulín však hraje také významnou úlohu v mozku, kde funguje jako neuropeptid. Důkazy o tom, že inzulín je aktivním mozkovým hormonem, byly získány až v posledních letech 3- klinická data ukazují, že hraje významnou úlohu při fungování paměti. Působení inzulínu je realizováno přes inzulínové receptory, lokalizované zejména v bulbus olfactorius, v hypotalamu a hipokampu. Výsledky získané z experimentů na zvířatech ukazují na účinky inzulínu v mozku spojené s učením a pamětí. TaJcé kognitivní dysfunkce při demenci Alzheimerova typu AD) jsou spojeny s nedostatkem inzulínu v mozku a paměť u pacientů s AD se zlepšuje, když se hladina inzulínu zvýší.
Insulin is mainly known for its peripheral effects on the metabolism of glucose, fats, and proteins. However, insulin also exer ts impor- tant actions within the brain, and functions as a neuropeptide. Evidence for insulin being an active hormone in the brain has i ncreased greatly in recent years and some clinical data suggest that insulin plays an important role in memory performance. It acts via insulin receptors, localized predominantly in the olfactory bulbs, hypothalamus, and hippocampus. Data obtained in animal experiments r eveal an interesting insulin profile in the brain linked with learning and memory. Also cognitive dysfunctions in dementia of the Alz heimer type (AD) are associated with insulin deficiency in the brain, and memory improves in AD patients when insulin levels increase.
- MeSH
- Alzheimerova nemoc etiologie komplikace terapie MeSH
- demence enzymologie etiologie komplikace MeSH
- diabetes mellitus enzymologie metabolismus MeSH
- finanční podpora výzkumu jako téma MeSH
- inzulin metabolismus nedostatek terapeutické užití MeSH
- lidé MeSH
- lithium terapeutické užití MeSH
- poruchy paměti etiologie komplikace MeSH
- Check Tag
- lidé MeSH