The density scale height H is determined at low as well as high altitude using the equation of change rate of the orbital period of Dash 2 satellite. The computed values of H are compared with these statistical values obtained by Jacchia-Jacchia´s values of H are given up to altitude 2500 km. We extend Jacchia´s values of H up to altitude 3110.7 km since our values of H are computed from altitude 316.7 km to altitude 3110.7 km. Finally a comparison between our values and Jacciha´s values of H at diffenent altitudes and different MJD are given. For higher altitudes, out values of H are much greater than Jadchia´s values while at smaller altitudes, our values are approximately the same as Jacchia´s values.
We study the system of PDEs describing unsteady flows of incompressible fluids with variable density and non-constant viscosity. Indeed, one considers a stress tensor being a nonlinear function of the symmetric velocity gradient, verifying the properties of $p$-coercivity and $(p-1)$-growth, for a given parameter $p > 1$. The existence of Dirichlet weak solutions was obtained in [2], in the cases $p \ge 12/5$ if $d = 3$ or $p \ge 2$ if $d = 2$, $d$ being the dimension of the domain. In this paper, with help of some new estimates (which lead to point-wise convergence of the velocity gradient), we obtain the existence of space-periodic weak solutions for all $p \ge 2$. In addition, we obtain regularity properties of weak solutions whenever $p \ge 20/9$ (if $d = 3$) or $p \ge 2$ (if $d = 2$). Further, some extensions of these results to more general stress tensors or to Dirichlet boundary conditions (with a Newtonian tensor large enough) are obtained.
The age of the surfactant solution influences substantially effectiveness of drag reduction in a turbulent flow in tubes. In this paper are shown effects of both the surfactant concentration and the ratio of the surfactant to the compound containing counter ion, and their role in degradation rate at aging. and Stárnutí roztoku surfaktantu (povrchově aktivní látka) má velký vliv na účinnost snížení tření při turbulentním proudění vody v trubce. Byl zkoumán význam jak koncentrace surfaktantu, tak jeho poměru ke složce obsahující protiiont právě s ohledem na stárnutí roztoku.
Non-linearity is essential for occurrence of chaos in dynamical system. The size of phase space and formation of attractors are much dependent on the setting of nonlinear function and parameters. In this paper, a three-variable dynamical system is controlled by different nonlinear function thus a class of chaotic system is presented, the Hamilton function is calculated to find the statistical dynamical property of the improved dynamical systems composed of hidden attractors. The standard dynamical analysis is confirmed in numerical studies, and the dependence of attractors and Hamilton energy on non-linearity selection is discussed. It is found that lower average Hamilton energy can be detected when intensity of nonlinear function is enhanced. It indicates that non-linearity can decrease the energy cost triggering for dynamical behaviors.
Index of vulnerability is a parameter based on ventricular gradient evaluating the risk of arrhythmia development. The index is derived from isointegral maps of the QT interval. Individual characteristics of isointegral maps are influenced by different factors, which contribute to the relatively high variability among measured parameters of maps in measured subjects. While several electrocardiographic indexes have been introduced, there are only few studies of their dependence on heart rate. In this study we set out to establish the dependence of vulnerability index on the RR interval or heart rate in healthy population. A positive linear correlation between RR intervals and mean and minimum values of vulnerability indexes was found., J. Martinka, K. Kozlíková., and Obsahuje bibliografii
This article presents the extraordinary discoveries of ceramic vessel deposits in wells of the Funnel Beaker culture (FBC). Such a custom is observed in all groups of this community but is of particular importance in the Eastern group of the FBC. In central Poland (Kuyavia) specifically, there are many objects of this type compared to older materials of the Linear Pottery culture. The analysis of the local contexts of these finds allows for the hypothesis that the two communities are closely related to be proposed. and Článek pojednává o mimořádných nálezech keramických nádob ve studnách z období kultury nálevkovitých pohárů (KNP). Zvyk ukládání nádob do studní se vyskytuje u všech skupin této kultury, ale zvláště významný je u východní skupiny KNP. Zejména početné nálezy ze středního Polska (Kujavy) dovolují srovnání s podobnými nálezy z doby kultury s lineární keramikou. Analýza lokálních souvislostí těchto nálezů umožňuje navrhnout hypotézu o příbuznosti obou komunit.
Na k. ú. obce Hrádečná (okr. Chomutov, Ústecký kraj) byl při amatérském detektorovém průzkumu v roce 2003 objeven hromadný nález výzbroje a výstroje z doby římské čítající celkem 21 železných předmětů a vážící 2,3 kg. Součást výzbroje tvoří meč a 11 hrotů kopí/oštěpů; výstroj je zastoupena elementy několika štítů (4 puklice, 5 držadel). Na základě typologicko-chronologické analýzy lze předměty datovat rámcovým rozpětím stupňů B1–C1. Charakteristickým rysem souboru je jeho intencionální zničení. Nález umístěný mimo sídelní a funerální areály představuje ojedinělý doklad lidské aktivity v době římské v centrální části Krušných hor. Přes nejisté nálezové okolnosti lze klást soubor do souvislostí s rituálním chováním a interpretovat jej jako ireverzibilní depot uložený někdy na přelomu starší a mladší doby římské z votivních důvodů. and An amateur metal detector survey conducted in 2003 in the cadastre of the town of Hrádečná (Chomutov district, Ústí nad Labem Region) uncovered a mass find of arms and gear from the Roman Period with a total of 21 iron artefacts weighing 2.3 kg. The weapons include a sword and 11 lances/spears; gear is made up of parts of several shield (4 bosses, 5 grips). Based on a typological-chronological analysis, the artefacts can be dated in general to the interval between phases B1–C1. A characteristic trait of the assemblage is its intentional destruction. Made outside settlement and burial areas, the find is an extraordinary document of human activity in the Roman Period in central Erzgebirge Mts. Despite the uncertain find circumstances, the assemblage can be connected with ritual behaviour and interpreted as an irreversible hoard buried for votive reasons roughly between the Early and Late Roman Period.
When research of the Roman ditch in the Neurissen tract in Mušov (Moravia, The Czech Republic) took place, only entirely isolated artifacts were found in areas situated next to the heights of the perimeter of the Burgstall hill. Animal bones, consisting in several cases of articulated parts of skeletons, had a special role (ditches Mušov-Neurissen II and Mušuv-Neurissen IV where the human skeletons were also found.) Interpretation of the finds in this position is impossible without reference to other sites. Therefore we present several comparative examples of analogical finding situations in places where the Roman army presence was proven (Ruhhof, Hulín-Pravčice, Pilismarót-Szobi rév, Stillfried, Newstead, Brno-Vojtova street). Attention is also given to other places with significant strength of evidence (Regensburg-Harting, Kaiseraugst, Bratislava-Rusovce, Kalkriese).
This study sought to evaluate whether consumption of polyphenol extract from Cognac (CPC) modulates platelet activation and cardiovascular reactivity in rats. Male Wistar rats were treated daily for 4 weeks by intra-gastric gavage receiving CPC at 80 mg/kg/day or vehicle (5 % glucose). Platelet adhesion and aggregation in response to different activators were assessed. Cardiac and vascular reactivity in response to various agonists as well as NO measurement by electron paramagnetic resonance technique were investigated in isolated heart and thoracic aorta. Oral administration of CPC decreased platelet aggregation induced by ADP but not by collagen. CPC did not affect adhesion to collagen. The chronotropic but not the inotropic response to isoprenaline was reduced without alteration of NO production in hearts from CPC-treated rats. CPC treatment did not affect ex vivo relaxation to acetylcholine nor NO content of rat aorta. CPC did not significantly alter the response to phenylephrine in aorta despite the participation of endothelial vasoconstrictor products. In summary, chronic treatment with CPC has no impact on ex vivo vascular and cardiac reactivity; however, it reduced heart work and platelet aggregation. These data suggest the existence of compounds in Cognac that may decrease the risk of coronary thrombosis and protect against some cardiac diseases., J. Švíglerová, J. Kuncová, L. Nalos, J. Slavíková, M. Štengl., and Obsahuje bibliografii a bibliografické odkazy
Lithium-pilocarpine status epilepticus (SE) resulted in delayed changes of single cortical in terhemisperic (transcallosal) responses in immature rats. Low-frequency stimulation inducing depression and/or potentiation was studied to analyze possible dynamic changes in cortical responses. Status was elicited in 12-day-old (SE12) or 25-day-old (SE25) rats. Control siblings received saline instead of pilocarpine. Interhemispheric responses were elicited by stimulation of the sensorimotor region of the cerebral cortex 3, 6, 9, 13, or 26 days after status. A series of 5 biphasic pulses with intensity equal to twofold threshold were used for stimulation. The interval between pulses was 100, 125, 160, 200 or 300 ms, eight responses were always averaged. Peak amplitude of the first positive, first negative and second positive waves was measured and responses to the second, third, fourth and fifth pulse were compared with the first one. Animals after status epilepticus as well as lithium-paraldehyde controls exhibit a frequency depression at nearly all the intervals studied. An outlined increase of responses in SE rats in comparison with the controls three days after SE stayed just below the level of statistical significance. In addition, animals in the SE12 group exhibited potentiation of responses at this interval after SE. With longer intervals after SE, the relation between SE and control animals changed twice resulting in a tendency to lower amplitude of responses in SE than in control rats 26 days after SE. Rats in the SE25 group exhibited higher responses than controls 13 days after status, but this difference was not present at the longest interval after SE. Low-frequency stimulation did not reveal increased cortical excitability as a long-lasting consequence of status epilepticus induced in immature rats. In addition, the outlined differences between SE and control rats changed with the time after SE., G. Tsenov, P. Mareš., and Obsahuje bibliografii a bibliografické odkazy