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1312. Accretion disks in soft potential wells
- Creator:
- Duschl, Wolfgang J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- astrophysics and accretion
- Language:
- Czech
- Description:
- The softer a potential is, the closer the corresponding Keplerian rotation is to a rigid rotation law. Because of the small radial coupling in such a situation the radial mass flow due to viscosity in an α-accretion disk is very inefficient. Here a model is presented in which the mass of an accretion disk in a soft potential well changes this potential in a sense that an efficient mass flow in radial direction becomes possible, thus making the formation of a centra! mass condensation possib!e. This mechanism is of interest in the context of galactic central regions since it is capable of explaining the existence of centra! masses such as observed in the cores of norma! galaxies; it might aiso be of relevance for the explanation of the activity in AGNs.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1313. Accumulation of photosynthetic pigments in Larix decidua Mill. and Picea abies (L.) Karst. cotyledons treated with 5-aminolevulinic acid under different irradiation
- Creator:
- Maximová, N. and Slováková, Ľudmila.
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fotosyntéza, photosynthesis, chlorophyll biosynthesis, D1 protein, light-harvesting complex, protochlorophyllide, 2, and 581
- Language:
- Multiple languages
- Description:
- European larch (Larix decidua Mill.) and Norway spruce [Picea abies (L.) Karst.] synthesize chlorophyll (Chl) in darkness. This paper compares Chl accumulation in 14-d-old dark-grown seedlings of L. decidua and P. abies after shortterm (24 h) feeding with 5-aminolevulinic acid (ALA). We used two ALA concentrations (1 and 10 mM) fed to cotyledons of both species in darkness and in continuous light. The dark-grown seedlings of L. decidua accumulated Chl only in trace amounts and the seedlings remained etiolated. In contrast, P. abies seedlings grown in darkness were green and had significantly higher Chl content. After ALA feeding, higher protochlorophyllide (Pchlide) content was observed in L. decidua than in P. abies cotyledons incubated in darkness. Although short-term ALA feeding stimulated the synthesis of Pchlide, Chl content did not change significantly in cotyledons incubated in darkness. The Chl accumulation in cotyledons fed with ALA was similar to the rate of Chl accumulation in the controls. Higher Chl accumulation was reported in control samples after illumination: 86.9% in L. decidua cotyledons and 46.4% in P. abies cotyledons. The Chl content decreased and bleaching occurred in cotyledons incubated with ALA in light due to photooxidation. Analyses of Chlbinding proteins (D1 and LHCIIb) by Western blotting proved differences between Chl biosynthesis in L. decidua and P. abies seedlings in the dark and in the light. No remarkable increase was found in protein accumulation (D1 and LHCIIb) after ALA application. Our results showed interspecific difference in Chl synthesis between two gymnosperms. Shortterm ALA feeding did not stimulate Chl synthesis, thus ALA synthesis was not the rate-limiting step in Chl synthesis in the dark., N. Maximová, Ľ. Slováková., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1314. Accuracy issues in experimental studies of tilt sensors
- Creator:
- Łuczak, Sergiusz
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- test rig, tilt sensor, accuracy, and experimental studies
- Language:
- English
- Description:
- Problems related to accuracy of tilt measurements realized during experimental studies of miniature tilt sensors (including MEMS devices) are minutely discussed. The measurements are performed by means of a custom computer controlled test rig, over the full range of pitch and roll. Accuracy of the test rig is determined in terms of uncertainty of the measurements involved. Ways of improving performance of the test rig are briefly introduced. Exemplary results of experimental works are presented. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1315. Accuracy of ANN based day-ahead load forecasting in Turkish power system: degrading and improving factors
- Creator:
- Tanidir , Ö. and Tör, O. B.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- absolute percentage error, artificial neural networks, day aheadd load forecasting, mean absolute percentage error, secondary reserve, and sensitivity
- Language:
- English
- Description:
- This paper presents development of a day ahead load forecasting (DALF) model for Turkish power system with an artificial neural network (ANN). Effects of special holidays including national and religious days, and hourly random load deviations observed in Turkish power system due to significant arc furnace loads are discussed. Performance of the ANN is investigated in the sense of both DALF performance - in terms of both daily mean absolute percentage error (MAPE) and hourly absolute percentage error (APE) - and hourly secondary reserves required to ensure supply/demand adequacy of the system. The most sensitive cities to DALF in terms of daily city temperature forecasts are ranked in order to reduce the input of the developed ANN and thereby to improve execution of the model. Candidate cities are determined based on both their placement with respect to climatic zones of the country and their contribution to the system load during peak hours. The results show that, although a well-trained ANN could provide very satisfactory daily MAPEs at non-special days, such as ~1%, the hourly absolute percentage errors (APE) could be significant due to large random load disturbances, which necessitate special attention during the day ahead allocation of hourly secondary reserves. By limiting the temperature data set with major cities, the input of ANN reduces significantly while not disturbing the MAPEs. Main contributions of the study are; addressing both benefits of the prioritizing the cities in a power system in the sense of their temperature forecast effects on the DALF performance and assessing the performance of DALF in the sense of necessary amount of secondary reserves in power systems which include significant random load deviations (e.g., large arc furnace loads).
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1316. Accuracy of Earth gravity field models as a function of order of harmonic coefficients and a draft of laser geodynamic twin-satellite
- Creator:
- Klokočník, J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Earth gravity models, harmonic coefficients, and twin-satellite
- Language:
- Czech
- Description:
- The information on the accuracy of harmonic coefficients C1m, S1m as about a non-monotonic function of order m has been obtained from analysis of standard deviations of athe lumped coefficients compited from standart deviations of harmonic coefficients of various recent Earth gravity models as well as from resonant solutions for the individual orders. It is shown that the acuracy is lower for 8< m < 11 than for 12 < m < 15. A draft of new laser geodynamic twin-satellite is presented. The aim of the experiment, theoretical basis and suggestions to orbit selection - with ~8 to 11 revs. „day^-1 - are described; some comments to a possible design of the satellites and to their separation are also given.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1317. Accuracy of the relative gravity measurement
- Creator:
- Lederer, Martin
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, geodynamika, geodynamics, accuracy, precision, relative gravimetry, 7, and 551
- Language:
- English
- Description:
- Precise relative gravimeters achieve the internal precision about a few μGal 1, even in field conditions. Nevertheless this precision is in fact concerned with the instant of measurement and can not be confused with the accuracy of the gravity at the gravity station, which is influenced by other effects. The best approach of these two values is question of high-quality elimination of instrumental errors and time-variable disturbing effects affecting the relative gravity measurements., Martin Lederer., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1318. Accurate normalization factor for wire myography of rat femoral artery
- Creator:
- Peter Slezák, Waczulíková, I., Peter Bališ, and Angelika Púzserová
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, wire myograph, normalization procedure, rat femoral artery, 14, and 612
- Language:
- English
- Description:
- Wire myograph is a device for the in vitro investigation of both, active and passive properties of arteries. Arteries from a variety of animal species, pathological states, and vascular beds were investigated using this method. We focus on the normalization procedure which is aimed to standardize experimental settings and, in part, to simulate physiological conditions. During normalization, it is determined the internal circumference of a vessel stretched to a tension that corresponds to the transmural pressure of 100 mm Hg (IC100). Once it is determined, the internal circumference is traditionally set to (0.9 ⋅ IC100). However, this constant 0.9, called also the normalization factor (NF), was experimentally determined for rat small mesenteric arteries only. Therefore, the aim of our work was to show the influence of different NFs on the passive tension and reactivity of both, rat femoral arteries (FA) an d the first branches of superior mesenteric arteries (MA). We found out that the maximal active wall tension of the FA was achieved at the NF value of 1.1, and that of the MA at 0.9. Considering the values of the active wall tension we suggest that higher reactivity and better signal-to- noise ratio in FA can be achieved when the NF is set at least to 1.0., P. Slezák, I. Waczulíková, P. Bališ, A. Púzserová., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1319. Accurate reduction of a model of circadian rhythms by delayed quasi-steady state assumptions
- Creator:
- Vejchodský, Tomáš
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- biochemical networks, gene regulatory networks, oscillating systems, periodic solutions, model reduction, and accurate approximation
- Language:
- English
- Description:
- Quasi-steady state assumptions are often used to simplify complex systems of ordinary differential equations in the modelling of biochemical processes. The simplified system is designed to have the same qualitative properties as the original system and to have a small number of variables. This enables to use the stability and bifurcation analysis to reveal a deeper structure in the dynamics of the original system. This contribution shows that introducing delays to quasi-steady state assumptions yields a simplified system that accurately agrees with the original system not only qualitatively but also quantitatively. We derive the proper size of the delays for a particular model of circadian rhythms and present numerical results showing the accuracy of this approach.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1320. Accusative resumptive pronoun in the Czech relative clauses with absolutive relativizer co
- Creator:
- Fried, Mirjam
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- relative clause, relativizer, resumptive pronoun, corpus analysis, vztažná věta, relativizátor, absolutní relativum, and korpusová analýza
- Language:
- Czech
- Description:
- This paper addresses the poorly understood patterning in the presence vs. absence of the accusative resumptive pronoun in the Czech relative clauses (RC) introduced by the absolutive relativizer co. Using both qualitative and frequency-based quantitative analysis, I investigate the distribution of the resumptive pronoun in authentic usage as attested in the Czech National Corpus. The study leads to the conclusion that the criteria that determine the distribution of the accusative resumptive pronoun go well beyond the traditionally invoked need for expressing agreement categories (gender, number) and grammatical relations (accusative object) or that the presence vs. absence of the pronoun should depend exclusively on the animacy of the relativized noun. Instead, the distribution appears to depend on the semantic compatibility between the relativized noun and the proposition expressed by the RC, reflecting a functional distinction between a determinative and non-determinative (explicative) interpretation of the RC; the former is unambiguously signaled by the bare relativizer co, the latter is available with the analytic co + resumptive pronounACC pattern as one of the interpretive options. and Článek se zabýv| problémem akuzativního z|jmena ve vztažných větách uvozených nesklonným co v češtině a hled| odpověď na dosud nezodpovězenou otázku, čím je v těchto větách přítomnost či nepřítomnost anaforického akuzativu podmíněna. Na základě kvalitativní i frekvenční analýzy korpusového materiálu docházíme k závěru, že korpus nijak nepotvrzuje tradičně postulovaná kritéria pro používání akuzativního zájmena, jimiž má být nutnost vyj|dřit gramatickou shodu s řídícím substantivem (v rodu a čísle) a gramatickou funkci ve vztažné větě (předmět) či role, kterou m| hr|t životnost řídícího substantiva (preferenční souvýskyt akuzativního z|jmena a neživotných substantiv). Rozbor autentického materi|lu naopak nasvědčuje tomu, že distribuce akuzativního z|jmena ve vztažných vět|ch s co je podmíněna sémantickou kompatibilitou mezi řídícím substantivem a propozičním obsahem vztažné věty, což se promítá do funkčního rozlišení mezi determinační a nedeterminační (explikativní) platností dané věty. Nepřítomnost anaforického akuzativu jednoznačně signalizuje funkci determinační, zatímco použití anaforického zájmena umožňuje obojí interpretaci.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public