In this paper, we consider the Swift-Hohenberg equation with perturbed boundary conditions. We do not a priori know the eigenfunctions for the linearized problem since the SO(2) symmetry of the problem is broken by perturbation. We show that how the neutral stability curves change and, as a result, how the bifurcation diagrams change by the perturbation of the boundary conditions.
In this paper we show that, for a given value of the energy, there is a bifurcation for the two imaginary centers problem. For this value not only the configuration of the orbits changes but also a change in the topology of the phase space occurs.
We consider parameter-dependent cocycles generated by nonautonomous difference equations. One of them is a discrete-time cardiac conduction model. For this system with a control variable a cocycle formulation is presented. We state a theorem about upper Hausdorff dimension estimates for cocycle attractors which includes some regulating function. We also consider the existence of invariant measures for cocycle systems using some elements of Perron-Frobenius theory and discuss the bifurcation of parameter-dependent measures.
Cíle. Cílem studie bylo odhadnout základní psychometrické charakteristiky české verze metody pro měření pěti obecných dimenzí osobnosti Big Five Inventory 2 (BFI-2) a jeho zkrácených verzí (BFI-2-S, BFI-2XS).
Výzkumný soubor. BFI-2 byl předložen pro sebeposouzení 1733 respondentům (42,1 % mužů a 57,9 % žen) ve věku od 15 do 26 let s průměrným věkem 20,06 let (SD = 2,53).
Hypotéza. Autoři předpokládali, že české verze inventáře budou mít srovnatelné psychometrické vlastnosti s originálními verzemi.
Analýza dat. Pro odhad vnitřní konzistence škál BFI-2, BFI-2-S, BFI-2-XS a subškál BFI-2, BFI-2-S byl použit Cronbachův koeficient alfa doplněný o ordinální variantu McDonaldova koeficientu omega, test-retestová stabilita tří metod byla odhadnuta pomocí Pearsonova korelačního koeficientu. Struktura inventáře BFI-2 na úrovni položek a subškál byla odvozena z analýzy hlavních komponent s následnou rotací Varimax. Vnitřní struktura jednotlivých škál byla dále ověřována pomocí konfirmační faktorové analýzy (CFA). Schopnost škál BFI-2-S a BFI- 2-XS reprezentovat celkové skóry z nezkrácené verze BFI-2 byla zjišťována pomocí Pearsonova koeficientu korelace.
Výsledky. Škály BFI-2 mají dobrou reliabilitu, která se pohybuje od 0,81 do 0,89. Reliabilita subškál je uspokojivá a pohybuje se od 0,56 do 0,83 (M = 0,74). Průměrná test-retestová stabilita BFI-2 po 6 měsících byla 0,86 pro škály a 0,80 pro subškály. Všechny položky BFI-2 dosahují faktorového náboje většího nebo rovného 0,30 na odpovídajícím faktoru. V české verzi BFI-2 se za použití CFA replikovala hierarchická struktura s 15 subškálami, stejně jako v původní verzi. Zkrácená verze BFI-2-S a BFI-2-XS rekonstruuje z 91 % a 77 % skóry škál BFI-2.
Limitace. Studie neobsahuje důkazy o konvergentní validitě and Objectives. The aim of the study was estimation of basic psychometric properties of the Czech adaptation of the Big Five Inventory 2 (BFI-2) measuring five basic personality dimensions and their short and extra short versions (BFI-2-S, BFI-2XS).
Subject and settings. The BFI-2 was administered to 1,733 participants (42.1% men, 57.9% women) in age range from 15 to 26 years (M = 20.06, SD = 2.53).
Hypothesis. Authors expected that the Czech adaptation of the BFI-2, BFI-2-S, BFI-2XS will retain comparable psychometric properties to the original versions.
Statistical analysis. Internal consistency of BFI- 2, BFI-2-S, BFI-2XS domains and BFI-2, BFI- 2-S facets was estimated using Cronbach’s alpha coefficient and ordinal McDonald’s omega coefficient. Test-retest stability of the three methods was estimated using Pearson’s correlation coefficient. The structure of the BFI-2 at the level of items was explored using Principal Component Analysis with Varimax rotation; structures of domains were confirmed using Confirmatory Factor Analyses. The ability of the BFI-2-S and BFI-2-XS scales to represent BFI-2 scores was assessed using the Pearson correlation coefficient.
Results. The BFI-2 domains showed good internal consistency, ranging from 0.81 to 0.89. Internal consistency of individual facets ranged from 0.56 to 0.83 (M = 0.74). Average BFI-2 test-retest reliability estimated over a 6 month period was r = 0.86 for domains and r = 0.80 for facets. All items of the BFI-2 showed factor loadings 0.30 or higher on intended factor. The BFI-2 hierarchical structure with 15 facets was confirmed using CFA. Short versions BFI-2-S and BFI-2-XS captured 91% and 77% of the domains of the full version of BFI-2 inventory.
Study limitation. Convergent validity of the instrument and the self-other agreement was not evaluated.
The incidence of diabetes mellitus is rising worldwide. The aim of this prospective epidemiological study was to compare the effects of natural and surgical menopause on parameters of glucose metabolism. In a group of 587 repeatedly examined women, with a baseline age of 45-55 years, the following subgroups of women were separated: those after bilateral oophorectomy (BO, n=37) and those in natural menopause (NAT, n=380) including women menopausal already at baseline (POST, n=89). The study parameters including glycemia, insulinemia, HOMA-IR and betacell function using HOMA-β were determined at baseline and 6 years later. Over the study period, there was a marked rise in prediabetic and diabetic values of fasting glycemia; the percentage of women with diabetic values increased in the NAT (from 0.8 % to 3.9 %) and POST (from 2.2 % to 9.0 %) subgroups, with the highest prevalence in the BO subgroup (from 8.1 % to 10.8 %). While, among women with non-diabetic fasting glycemia, an increase in fasting glycemia was observed in all study subgroups, it was more marked in the BO subgroup than in the NAT and POST ones (p=0.02 both). This difference between NAT and BO was also found in the long-term trend of development of glycemia in non-diabetic women (p=0.014). Compared with natural menopause, bilateral oophorectomy may have an adverse effect on glucose metabolism., M. Lejsková, J. Piťha, S. Adámková, O. Auzký, T. Adámek, E. Babková, V. Lánská, Š. Alušík., and Obsahuje bibliografii
Infection with the liver fluke Opisthorchis viverrini (Digenea) (Poirier, 1886) causes bile duct injury and periductal fibrosis by chronic overproduction of inflammatory-mediators and eventually results in cholangiocarcinoma development. While extensive research works have been done on O. viverrini infection-associated changes of bile ducts and periductal fibrosis, little attention was paid on morphological and biochemical changes of the bile canaliculi (BC), the origin of bile flow. We aimed to investigate the morphological and functional alterations of BC in the liver of hamsters infected with O. viverrini at one and three months post-infection. Ultrastructural changes of BC showed dilatation of BC and significant reduction of the density of microvilli as early as at one month post-infection. Immunohistochemistry revealed that CD10, a BC marker, expression was reduced early as one month post-infection. The mRNA expression of the genes encoding molecules related to bile secretion including bile acid uptake transporters (slc10a1 and slco1a1), bile acid dependent (abcb11) and independent (abcc2) bile flow and bile acid biosynthesis (cyp7a1 and cyp27a1) were significantly decreased at one month post-infection in association with the reduction of bile volume. In contrast, the expression of the mRNA of bile acid regulatory genes (fxr and shp-1) was significantly increased. These changes essentially persisted up to three months post-infection. In conclusion, O. viverrini infection induces morphological and functional changes of BC in association with the decrease of bile volume.
The study deals with the role, so-called "white ballots" played in the political development of Czechoslovakia in the years 1945-1948. and Článek zahrnuje poznámkový aparát pod čarou
We investigated the gastric response to an ulcerogenic irritant and the change in gastric functions in an experimental rat model of obstructive jaundice, with or without biliary drainage. After biliary obstruction for 14 days, rats with ligated bile duct (BDL) were randomly divided into three groups: BDL group without biliary drainage, BDL followed by choledochoduodenostomy (CD) or a choledochovesical fistula (CVF). The gastric functions were evaluated 2 weeks after the surgery. Gastric damage, induced by orogastric administration of ethanol, was evaluated 30 min later using a lesion index and microscopic scoring was then performed on fixed stomachs. Basal gastric acid secretion was measured by the pyloric ligation method.The lesion index and maximum lesion depth did not differ in the BDL and sham groups, while they were significantly reduced in the CD group. Gastric acid output and secretory volume were reduced in the BDL group compared to the sham group, while these reductions were abolished in the CD group. Afferent denervation with capsaicin further reduced the ulcer index in the later group. Our data suggest that gastric mucosal susceptibility to injury is dependent on the normal flow of bile into the duodenal lumen, which appears to be a requirement for adaptive gastric cytoprotection., A. Cingi, R. Ahiskali, B. K. Oktar, M. A. Gülpinar, C. Yegen, B.Ç. Yegen., and Obsahuje bibliografii
The complex architecture of the liv er biliary network represents a structural prerequisite for the formation and secretion of bile as well as excretion of toxic substances through bile ducts. Disorders of the biliary tract affect a significant portion of the worldwide population, often leading to cholestatic liver diseases. Cholestatic liver disease is a condition that results from an impairment of bile formation or bile flow to the gallbladder and duodenum. Cholestasis leads to dramatic changes in biliary tree architecture, worsening liver disease and systemic illness. Recent studies show that the preva lence of cholestatic liver diseases is increasing. The availability of well characterized animal models, as well as development of visualization approaches constitutes a critical asset to develop novel pathogenetic concepts and new treatment strategies., L. Sarnova, M. Gregor., and Obsahuje bibliografii