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34122. Upozorňují sklípkánci na pravěké osídlení?
- Creator:
- Řezáč, Milan
- Type:
- article, model:article, and TEXT
- Language:
- Czech
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
34123. Upper airway dilator muscle weakness following intermittent and sustained hypoxia in the rat: effects of a superoxide scavenger
- Creator:
- Skelly, J. R., Rowan, S. C., Jones, J. F. X., and O´Halloran, K. D.
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, antioxidants, fatigue, hypoxia/re-oxygenation, intermittent hypoxia, superoxide scavenger, obstructive sleep apnoea syndrome, upper airway muscles, 14, and 612
- Language:
- English
- Description:
- Obstructive sleep apnoea syndrome (OSAS) is a common disorder associated with upper airway muscle dysfunction. Agents that improve respiratory muscle performance may have considerable therapeutic value. We examined the effects of acute exposure to sustained and intermittent hypoxia on rat pharyngeal dilator muscle function. Additionally, we sought to test the efficacy of antioxidant treatment in ameliorating or preventing hypoxia-related muscle dysfunction. Isometric contractile and endurance properties of isolated rat sternohyoid muscle bundles were examined at 35 °C in vitro. Muscle bundles were exposed to one of four gas treatments: hyperoxia (control), sustained hypoxia (SH), intermittent hypoxia (IH) or hypoxia/reoxygenation (HR), in the absence or presence of the superoxide scavenger – Tempol (10 mM). Stress-frequency relationship was determined in response to electrical stimulation (10-100 Hz in increments of 10-20 Hz, train duration: 300 ms). Muscle performance was also assessed during repetitive muscle stimulation (40 Hz, 300 ms every 2 s for 2.5 min). Compared to control, IH and HR treatments significantly decreased sternohyoid muscle force. The negative inotropic effect of the two gas protocols was similar, but both were of lesser magnitude than the effects of SH. SH, but not IH and HR, increased muscle fatigue. Tempol significantly increased sensitivity to stimulation in all muscle preparations and caused a leftward shift in the stressfrequency relationship of IH and SH treated muscles. Tempol did not ameliorate sternohyoid muscle fatigue during SH. We conclude that Tempol increases upper airway muscle sensitivity to stimulation but only modestly ameliorates respiratory muscle weakness during intermittent and sustained hypoxic conditions in vitro. Respiratory muscle fatigue during sustained hypoxia appears unrelated to oxidative stress., J. R. Skelly, ... [et al.]., and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
34124. Upper bounds on the node numbers of hidden layers in MLPs
- Creator:
- Liu, Jiang, Ni, Feng, Du, Mingjun, Zhang, Xuyang, Que, Zhongli, and Song, Shihang
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- feedforward neural network, hidden node, multilayer perceptron (MLP), and upper bound
- Language:
- English
- Description:
- It is one of the fundamental and challenging problems to determine the node numbers of hidden layers in neural networks. Various efforts have been made to study the relations between the approximation ability and the number of hidden nodes of some specific neural networks, such as single-hidden-layer and two-hiddenlayer feedforward neural networks with specific or conditional activation functions. However, for arbitrary feedforward neural networks, there are few theoretical results on such issues. This paper gives an upper bound on the node number of each hidden layer for the most general feedforward neural networks called multilayer perceptrons (MLP), from an algebraic point of view. First, we put forward the method of expansion linear spaces to investigate the algebraic structure and properties of the outputs of MLPs. Then it is proved that given k distinct training samples, for any MLP with k nodes in each hidden layer, if a certain optimization problem has solutions, the approximation error keeps invariant with adding nodes to hidden layers. Furthermore, it is shown that for any MLP whose activation function for the output layer is bounded on R, at most k hidden nodes in each hidden layer are needed to learn k training samples.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
34125. Úprava čela kapiláry v optické kvalitě
- Creator:
- Studenovský, Karel and Hošek, Jan
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- small surfaces, grinding, polishing, cleaning, malé plochy, broušení, leštění, and čištění
- Language:
- Czech
- Description:
- An article presents technology of grinding and polishing of small glass areas down to 1 mm2 with optical quality. This technology problem relates to grant project solution ''Metastable water and water vapor'' GAČR No. 101/05/2214, where the surface tension of supercooled water has to be measured. We present experimental results of three possible technology approach of capillary tip finishing of final dimension 0.98/0.32 mm. Special focus is attended to capillary mounting appropriate for both machining and later experimental application too. and Příspěvek je zaměřen na technologii broušení a leštění malých skleněných ploch cca do 1mm2 s optickou kvalitou. Zvládnutí této problematiky úzce souvisí s měřením povrchového napětí přechlazené vody v rámci spoluúčasti autorů na řešení grantu ''Metastabilní voda a vodní pára'' GAČR č. 101/05/2214. Jsou uvedeny postupně tři možnosti opracování čela kapiláry s konečným rozměrem 0,98/0,32 mm včetně konkrétních výsledků. Pozornost je věnována i způsobu uchycení kapiláry, vhodným pro její montáž v experimentálním zařízení. To umožňuje sledovat změny tvaru mensiku kapaliny uvnitř kapiláry.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
34126. Úprava elipsometru Gaertner L119 a jeho použití pro studium tenkých vrstev
- Creator:
- Lesňák, Michal, Luňáček, Jiří, Talik, Adam, Hlubina, Petr, and Pištora, Jaromír
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Ellipsometry, thin films, Elipsometrie, and tenké vrstvy
- Language:
- Czech
- Description:
- This article deals with modification and renovation of the ellipsometer Gaertner L119 and its using for thin-film structures study. The measurement process is fully automatized. The device works at constant wavelength in PCSA null regime and the data are obtained for various angles of incidence. The system was tested on a set of SiO2 thin-films prepared on Si single crystal wafers by thermal oxidation at 1200°C. The thicknesses obtained from experiment were compared with the results obtained by using of Yamaguchi type spectral ellipsometric system as well as with the data determined from white-light interferometry and spectral reflectometry. and Předložená práce se zabývá popisem úprav a modernizace elipsometru Gaertner L119 a jeho využitím pro studium tenkých vrstev s automatizovaným režimem měřicího procesu. Zařízení se využívá jako nulovací elipsometr v konfiguraci PCSA pro měření na jedné vlnové délce při různých úhlech dopadu. K testování přístroje byla provedena měření tloušťky vrstev SiO2 připravených termickou oxidací na monokrystalických křemíkových deskách při teplotě 1200 °C. Naměřené tloušťky byly porovnány jednak s výsledky měření na spektrálním elipsometru systému Yamaguchi a také s interferometrickými a reflektometrickými měřeními v bílém světle.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
34127. Úprava otvoru sloupku pro kinematicky tuhé upevnění tyčky
- Creator:
- Miler, Miroslav
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Language:
- Czech
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
34128. Upregulation of genes involved in cardiac metabolism enhances myocardial resistance to ischemia / reperfusion in the rat heart
- Creator:
- Ravingerová, T., Slávka Čarnická, Ledvényiová, V., Barlaka, E., Galatou, E., Chytilová, A., Mandíková, P., Nemčeková, M., Adriana Adameová, František Kolář, and Lazou, A.
- Format:
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, apoptóza, apoptosis, myocardial ischemia, delayed preconditioning, RRAR activation, metabolic genes, WY-14643, 14, and 612
- Language:
- English
- Description:
- Genes encoding enzymes involved in fatty acids (FA) and glucose oxidation are transcriptionally regulated by peroxisome proliferator-activated receptors (PPAR), members of the nuclear receptor superfamily. Under conditions associated with O 2 deficiency, PPAR-α modulates substrate switch (between FA and glucose) aimed at the adequate energy production to maintain basic cardiac function. Both, positive and negative effects of PPAR-α activation on myoc ardial ischemia/reperfusion (I/R) injury have been reported. Moreover, the role of PPAR-mediated metabolic shifts in cardioprotective mechanisms of preconditioning (PC) is relatively less investigated. We explored the effects of PPAR-α upregulation mimicking a delayed “second window” of PC on I/R injury in the rat heart and potential downstream mechanisms involved. Pretreatment of rats with PPAR-α agonist WY-14643 (WY, 1 mg/kg, i.p.) 24 h prior to I/R reduced post-ischemic stunning, arrhythmias and the extent of lethal injury (infarct size) and ap optosis (caspase-3 expression) in isolated hearts exposed to 30-min global ischemia and 2-h reperfusion. Protection was associated with remarkably increased expression of PPAR- α target genes promoting FA utilization (medium-chain acyl-CoA de hydrogenase, pyruvate dehydrogenase kinase-4 and carnitine palmitoyltransferase I) and reduced expression of glucose transporter GLUT-4 responsible for glucose transport and metabolism. In addition, enhanced Akt phosphorylation and protein levels of eNOS, in conjunction with blunting of cardioprotection by NOS inhibitor L-NAME, were observed in the WY-treated hearts. Conclusions: upregulation of PPAR-α target metabolic genes involved in FA oxidation may underlie a delayed phase PC-like protection in the rat heart. Potential non-genomic effects of PPAR-α-mediated cardioprotection may involve activation of prosurvival PI3K/Akt pathway and its downstream targets such as eNOS and subsequently reduced apoptosis., T. Ravingerová ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
34129. Upregulation of the mitochondrial alternative oxidase pathway improves PSII function and photosynthetic electron transport in tomato seedlings under chilling stress
- Creator:
- Zeng, J. J., Hu, W. H., Hu, X. H., Tao, H. M., Zhong, L., and Liu, L. L.
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- chlorophyll fluorescence, JIP-test, OJIP curve, salicylhydroxamic acid, and Solanum lycopersicum
- Language:
- Multiple languages
- Description:
- The aim of this study was to explore how the mitochondrial alternative oxidase (AOX) pathway alleviates photoinhibition in chilled tomato (Solanum lycopersicum) seedlings. Chilling induced photoinhibition in tomato seedlings despite the increases in thermal energy dissipation and cyclic electron flow around PSI (CEF-PSI). Chilling inhibited the function of PSII and blocked electron transport at the PSII acceptor side, however, it did not affect the oxygen-evolving complex on the donor side of PSII. Upregulation of the AOX pathway protects against photoinhibition by improving PSII function and photosynthetic electron transport in tomato seedlings under chilling stress. The AOX pathway maintained the open state of PSII and the stability of the entire photosynthetic electron transport chain. Moreover, the protective role of the AOX pathway on PSII was more important than that on PSI. However, inhibition of the AOX pathway could be compensated by increasing CEF-PSI activity under chilling stress.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
34130. Uptake, reflux, and excretion of bromosulfophthalein in ischaemia-reperfusion injury of rat liver
- Creator:
- Kukan, M., Bezek, Š., and Trnovec, T.
- Type:
- article, model:article, and TEXT
- Subject:
- ischaemia, reperfusion, liver, and bromosulfophthalein uptake, reflux, excretion
- Language:
- English
- Description:
- The uptake, reflux and excretion of bromosulfophthalein (BSP) were studied on a model of total warm ischaemia for 30 min (group 1) or 60 min (group 2) followed by reperfusion for 45 min in the isolated perfused rat liver of unfasting rats. In group 1, the BSP hepatic uptake was comparable to control livers (30 s ischaemia plus 45 min reperfusion), but was significantly reduced in group 2. The reflux of BSP from liver to perfusate in group 1 and group 2 resulted in the appearance of secondary concentration time peaks of BSP in the reservoir perfusate. This result suggests that ischaemia-reperfusion induced a qualitative change in BSP pharmacokinetics. Excretion of the dye into bile was significantly impaired in group 2 only. The leakage of lactate dehydrogenase into the perfusate was increased moderately in both group 1 and group 2 in comparison to the controls, suggesting a low degree of liver parenchymal injury. In conclusion, the results of this investigation showed that BSP pharmacokinetics were not only undergoing quantitative changes but also a qualitative change in the model of ischaemia-reperfusion injury of the liver obtained from fed rats and may thus serve as a highly sensitive indicator of liver viability.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public