This paper concentrates on the mathematical modelling for three-dimensional flow of an incompressible Oldroyd-B fluid over a bidirectional stretching surface. Mathematical formulation incorporates the effect of internal heat source/sink. Two cases of heat transfer namely the prescribed surface temperature (PST) and prescribed surface heat flux (PHF) are considered. Computations for the governing nonlinear flow are presented using homotopy analysis method. Comparison of the present analysis is shown with the previous limiting result. The obtained results are discussed by plots of interesting parameters for both PST and PHF cases. We examine that an increase in Prandtl number leads to a reduction in PST and PHF. It is noted that both PST and PHF are increased with an increase in source parameter. Further we have seen that the temperature is an increasing function of ratio parameter.
Fiber lasers are the youngest and most rapidly developing branch of lasers. Golden era of fiber lasers started only in early 2000’s and followed success of fiber amplifiers in telecommunications in nineties. Nowadays, the ytterbium fiber lasers at around 1 μm are the most powerful lasers available, reaching 100 kW of average output power. The 2 μm class fiber based on thulium-doped fibers are getting increasing importance thanks to better eye-safety, relaxed non-linear limits, more efficient processing of various materials, e.g., plastics, and high slope efficiency of up to 70 %. In the paper we review our recent progress in research of novel host materials for enhancements of fluorescence properties of thulium-doped fibers and new fiber-optic components and their applications in monolithic thulium-doped fiber laser. Results of coherent combination of thulium-doped fiber lasers are also presented. and Vláknové lasery patří mezi nejmladší a nejrychleji se rozvíjející typy laserů. Zlatá éra vláknových laserů začala teprve na začátku nového tisíciletí a navazuje na úspěch vláknových zesilovačů v telekomunikacích v devadesátých letech. Ytterbiem dopované vláknové lasery na vlnových délkách v okolí 1 μm jsou v současnosti vůbec nejvýkonnějšími dostupnými lasery, dosahují až 100kW průměrného výstupního výkonu. Vláknové lasery na 2 μm založené na thuliem dopovaných optických vláknech získávají nyní na významu díky menšímu riziku poškození zraku, menším omezením kvůli nelinearitám, vysoké účinnosti dosahující až 70 % a efektivnějšímu opracovávání některých materiálů, např. plastů. V příspěvku shrnujeme některé naše nedávné výsledky v oblasti výzkumu nových typů materiálů pro zlepšení fluorescenčních vlastností thuliem dopovaných vláken, nových typů vláknových optických součástek a jejich použití v monolitickém vláknovém laseru. Popisujeme rovněž výsledky výzkumu koherentního kombinování thuliem dopovaných vláknových laserů.
In plants external stimuli are perceived through a cascade of signals and signal transduction pathways. Protein phosphorylation and de-phosphorylation is one of the most important transduction paths for the perception of signals in plants. The highest concentrations of plant phospho-proteins are located in chloroplasts. This facilitates the protection of thylakoid membranes from stress-induced damage and augments adaptive strategies in plants. In this review, the protein kinases associated with phosphorylation of thylakoid membrane protein, and the adaptive changes in thylakoid membrane architecture and developmental cues are given. The presence of membrane bound kinases in thylakoid membranes have evolutionary implications for the signal transduction pathways and the photosynthetic gene expression for thylakoid membrane protein dynamics. and A. N. Misra, A. K. Biswal.
Ability of detergents digitonin (Dg), Triton X-IOO (TX), sodium dodecylsulphate (SDS), cetylpyridinium chloride (CPC), and Zwittergents 3-12 (Z-12), 3-14 (Z-14), and 3-16 (Z-16) to fragment unstacked thylakoid membranes was tested in French beán (Phaseolus vulgaris L.) leaves differing in age. The power of selected detergents to initiate fragmentation did not differ with different Chemical structure and molecular size of detergents, but it was controlled more probably by their molecular charge and shape. Unfavourable was the presence of positive charge and the absence of alkyl chain in detergent molecule. Membrane fragments obtained after the action of individual detergents on agranal thylakoids were separated on a Percoll gradient. Separated fractions were characterized by their chlorophyll (Chl) content, Chl a/b and Chl/protein ratios, position of absorption maximum (A^gx) i” spectral region and ratios of intensities of fluorescence emission bands. Since separation of no Chl-protein was achieved, no priority of detergent binding to any membrane component occurred under the conditions ušed. Fractions of similar density, products of the action of low concentrations of different detergents on the chloroplasts from leaves of the same age, differed in their characteristics. Low concentrations of detergents fragmented agranal membranes in a pattem which changed during leaf ontogeny. Only Z-16 had an increased capacity to extract proteins from membrane; this was probably promoted by the presence of 16-C alkyl chain.
Male Wistar rats were irradiated continuously with a daily dose of 0.19 Gy (120 days), 037 Gy (90 days) and 0.96 Gy (35 days) of gamma rays. An other group of rats was irradiated continuously with graded doses of gamma rays, up to total exposures ranging from 3.83-19.15 Gy. Depending on both the daily dose and total exposure, there was a decrease in phospholipid content in the thymus which correlated well with thymus weight changes. The decrease in triacylglycerol content was a less reliable sign of radiation damage. The phospholipid content reflecting the patterns of organ cellularity is a valuable indicator of the extent as well as recovery from radiation - induced injury to the thymus.
Numerous abnormalities of thyroid hormones in end-stage renal disease (ESRD) have been described. Our aim was to analyze the impact of these abnormalities on survival. In 167 hemodialyzed ESRD patients, TSH and thyroid hormone levels (T4, fT4, T3, fT3, rT3) were determined. The patients were then prospectively followed up for up to 5 years and the possible impact of any observed abnormalities on their mortality was studied. Only 16.8 % patients had all six tests within the reference range. The pattern of nonthyroidal illness syndrome was found in 56.3 %. Low T3 was particularly common (44.3 %), and clearly associated with increased 6- and 12-month mortality and decreased overall survival (log rank test, P=0.007). Independent of T3 levels (Spearman correlation, NS), increased rT3 was more frequently observed (9.9 %) than expected from the literature, and was also related to increased mortality and decreased survival (log rank test, P=0.021). Increased rT3 may be more common in ESRD patients than previously described, and together with decreased T3 it may serve as an indicator of poor prognosis in subsequent months., J. Horáček ... [et al.]., and Obsahuje seznam literatury
The GH4C1 pituitary cell line, an excellent model for a thyroid hormone action study, was used for determination of the relationship between thyroid hormone receptor occupancy and intensity of cell proliferation, prolactin (PRL) production, thyrotropin (TSH) inhibition and 3,5,3,-L-triiodothyronine (T3) receptor down-regulation. Nuclear receptor population was progressively occupied by T3 in concentrations ranging from 0.025 to 10.0 nM T3. Bmax ranged from 0.029 fmol/106 cells at the lowest T3 concentration to Bmax = 12.51 fmol/106 cells at the highest concentration. Each of the observed biological events is operative within distinct dose-response ranges in cultured GH4C1 cells. The maximal biological response (except the TSH inhibition and T3 receptor down-regulation) does not require the occupation of the whole nuclear receptor population by T3 and the intensity of none of the responses studied was directly proportional to thyroid hormone receptor occupancy.
The purpose of this study was to compare the daytime hourly responses of total thyroxine (T4) and triiodothyronine (T3) during an 8-hour recovery period following aerobic and anaerobic exercise to an equivalent non-exercise, control period. The data were examined for hourly mean differences as well as by determination of the integrated area under the curve (AGC) responses. Significant persistent elevations (hourly concentrations and AGC) from control levels in total T4 following both aerobic and anaerobic exercise were found. Total T3, however, was transiently elevated (only in the hourly concentration immediately following exercise) compared with the control following aerobic exercise, but remained unaffected by anaerobic exercise. No significant changes in the total T3 AGC responses were found due to exercise. The present findings demonstrate that exercise, aerobic and anaerobic, disrupts the daytime hourly pattern for total T4 in the blood, but apparently has minimal effect on total T3.
Thyroid hormones (TH) are powerful modulators of heart function, but their arrhythmogenic effects are less elucidated. We have examined both acute and long-term action of TH on the heart susceptibility to the ventricular fibrillation (VF) and on the heart ability to terminate VF and restore a sinus rhythm. Triiodothyronine (T3) was applied in the range of 10-9-10-6 mol/l in acute experiments using isolated perfused aged (14-month-old) guinea pig hearts. L-thyroxine (T4) was applied in the dose of 50 μg/100g/day to young (3-month-old) and aged (20-month-old) rats for 2 weeks. The T4 treatment resulted in an increased susceptibility of young, but not adult rat hearts to a hypokalemia induced VF and facilitated a spontaneous sinus rhythm (SSR) restoration in the latter group. The acute T3 administration in the range of 10-9-10-7 mol/l significantly decreased the susceptibility of an isolated heart to an electrically induced VF and also facilitated the sinus rhythm restoration. The SSR restoration was, however, not affected by 10-6 mol/l concentration of T3, which also led to an increased VF susceptibility. Results indicate that TH can affect the susceptibility of the heart to VF and its ability to restore the sinus rhythm via acute (non-genomic) and long-term (genomic) actions. Furthermore, an anti- and pro-arrhythmic potential of TH appears to be age- and dose-dependent., V. Knezl, T. Soukup, Ľ. Okruhlicová, J. Slezák, N. Tribulová., and Obsahuje bibliografii a bibliografické odkazy
Thyroid nodules are a very frequent pathology among common population. Despite the vast majority of them are of benign origin, the incidence of thyroid cancer is currently rather rising. Although there are several risk factors of thyroid cancer and several clinical, ultrasound, biochemical and molecular diagnostic markers, the exact mechanisms of thyroid oncogenesis and the linkage between thyroid nodule ultrasound appearance and its biological character remain unclear. While ionizing radiation is the only one well-known risk factor for thyroid cancer, the significance of some others remains unclear. The aim of our review was to discuss some not completely known pathophysiological mechanisms involved in thyroid oncogenesis as hypothyroidism, mutations of genes regulating cell proliferation, thyroid autoimmunity and pregnancy and to describe pathophysiological background of some ultrasound markers of thyroid cancer (size, echogenicity, vascularization, calcifications and stiffness). Better knowledge in this field is crucial for development of novel diagnostic techniques and therapeutic approaches. For exampl e, the analysis of BRAF, RAS and other mutations in cytological samples may help to distinction between follicular thyroid carcinoma and follicular thyroid adenoma and may signific antly decrease the number of unnecessary surgery among patients with thyroid nodules. Alternatively, the different malign cells growth, angiogenesis, destructions of thyroid follicles, reparative changes, growth retardation, fibrosis and increased interstitial fluid pressure implicate the typical ultrasound appearance of papillary thyroid cancer (hypoechogenicity, irregular vascularization, microcalcifications, stiffness) which is essential to catch the suspicious nodules on the basis of their ultrasound appearance among large amount of benign nodules., J. Krátký, H. Vítková, J. Bartáková, Z. Telička, M. Antošová, Z. Límanová, J. Jiskra., and Obsahuje bibliografii