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68772. The UV spectra of cataclysmic and symbiotic variables
- Creator:
- Selvelli, P. L. and Viotti, R.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- UV observations, cataclysmic variables, and symbiotic variables
- Language:
- Czech
- Description:
- UV observations of cataclysmic and symbiotic variables with the lUE satellite have given and are giving a fundamental contribution to our knowledge of the nature of these objects. The study of the UV resonance and intercombination lines of the most abundant elements has been used as a diagnostic of the physical conditions in the disk, circumstellar region, and ejecta. Most objects display a strong UV continuum which is usually attributed to emission from the hot component and/or from the accretion disk. The exceptionally long lifetime of lUE has allowed the study of these objects during different activity phases. In the recurrent nova T Cr B dramatic UV variations have been observed during phases of optical quiescence. Of particular interest has been the UV study of the recent outbursts of the symbiotic stars AG Dra, Z And, and PU Vul, as well.that of CH Cyg during the activity phases associated to the formation of a jet. The results of multi-frequency observations (from raďio to x-rays) of some symbiotic variables and their implications for the models are also discussed.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68773. The value of the ITS2 region for the identification of species boundaries between Alloxysta hyperparasitoids (Hymenoptera: Charipidae) of aphids
- Creator:
- van Veen, F.J. Frank, Belshaw, Robert, and Godfray, CHarles J.
- Type:
- article, model:article, and TEXT
- Subject:
- Alloxystinae, aphid, apparent competition, food web, hyperparasitoid, and ITS2
- Language:
- English
- Description:
- 1) Alloxystinae are major secondary parasitoids of aphids, important in both their ecology and pest management. 2) Two radically differing views of alloxystine taxonomy exist in the literature, in one of which the group is very diverse, in the other it consists of a few variable species. 3) We sequenced a variable nuclear gene region (ITS2) for 28 specimens of a morphologically clearly defined group which, in one view belong to a single species and in the other to four species. We find that the four putative species each carry a different unique allele with no intraspecific variation. We show that the probability of the observed distribution of alleles under the assumption of a single interbreeding population is very small and we reject the view that all specimens belong to a single biological species. 4) We discuss the implications of our results for aphid - parasitoid community ecology and the biological control of aphids with parasitoids.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68774. The variability of ice phenomena on the rivers of the Baltic coastal zone in the Northern Poland
- Creator:
- Łukaszewicz, Jan Tadeusz and Graf, Renata
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- ice phenomena, rivers, coastal zone, air temperature, NAO, and water temperature
- Language:
- Slovak
- Description:
- The main purpose of the research was to determine the conditions affecting ice phenomena, including the three-phase cycle of ice: expansion, retention and decay of the ice cover on selected rivers of the Baltic coastal zone in the Northern Poland (Przymorze region). The analysis has been elaborated for the years 1951–2010 against the backdrop of currently occurring climatic changes, with particular emphasis on the development and phase variability of the NAO. The article presents the impact of the variability in atmospheric circulation which has manifested in an increase in air temperature, over the last 20 years, on thermal conditions during winter periods in the South Baltic Coastal Strip. The increase in air temperature has contributed to an increase in the temperature of river waters, thus leading to a shortening of the duration of ice phenomena on rivers in the Przymorze region. The article also brings to light an increased occurrence of winter seasons classified as cool, and a disruption in the occurrence of periods classified as normal over the last 30 observed years. The research has demonstrated a significant dependence between the seasonal change in air temperature and the variability of thermal conditions of water, which has a direct impact on the variability of the icing cycle of rivers in the Przymorze region. The authors also show that the variability in forms of ice phenomena for individual river sections is determined by the local factors, i.e. anthropogenic activity, impact of urbanized areas or inflow of pollutants.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68775. The variability of the runaway star 53 Arietis
- Creator:
- Sterken, C.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- astrophysics, spectrographic observations, and star 53 Arietis
- Language:
- Czech
- Description:
- From photometric and spectrographic observations of the runaway star 53 Ari we confirm that the star did noat exhibit detectable light- and radial velocity variations. The star is definitely not a beta Cephei star.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68776. The variation of the frontal zone during the year in the area of the Atlantic and Europe and in relation to the solar activity
- Creator:
- Gregor, .Z. and Křivský, L.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- astrophysics and solar activity
- Language:
- Czech
- Description:
- I. The mean state of circulation in some of the months can be demonstrated by the mean position of the frontal zone. From the position of the frontal zone we can determine if the zonal or meridional circulation prevails, and in which way it will change during the year II. The long-range variation of the mean frontal zone in relation to solar activity expressed by Ejgenson s Index of Recurrency of Sunspots A is determined. The effect ascertained is especially significant in January. The results in maps show the deviations of frequencies of the zones from the mean state, partly in the years of minima, partly in the years of maxima of the recurrency of sunspots.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
68777. The vectorcardiographic QRS loop in pulmonary ventilation alterations in young healthy women
- Creator:
- Kujaník, Š., Baldovský, Ľ., and Linder, I.
- Type:
- article, model:article, and TEXT
- Subject:
- electrocardiography, vectorcardiography, hypoxia, hyperventilation, and Frank lead ECG
- Language:
- English
- Description:
- The influence of some pulmonary ventilation alterations (the normal ventilation at rest = control), the hyperventilation (HV) lasting 75 s, the hypoxic-hypercapnic ventilation (HXV) lasting 3 and 6 min) on the instantaneous QRS vectors was investigated in 42 young healthy women (19-24 years old). The magnitude and the direction of instantaneous QRS vectors in the 10th to the 70th ms and in QRS max were constructed from the Frank lead ECG. The significant alterations of the direction (angle) were found in the 30th ms and QRS max at HXV and in the 60th ms at HV. A significant decrease in the magnitude of instantaneous vectors was found in the 10th to 50th ms after 6 min of HXV, in the 30th to 50th ms at 3 min of HXV, in the 40th to 50th ms at HV. These alterations were the most marked in the horizontal plane. We suggest that the alterations of the instantaneous QRS vectors were caused by the influence of the autonomic nervous system or humoral agents, but not by heart position, Brody’s effect or lung hyperinflation.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
68778. The velocity-age relation for B and A stars
- Creator:
- Palouš, J. and Piskunov, A. E.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- A stars, B stars, and velocity-age relation
- Language:
- Czech
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
68779. The vibration plethysmographic method of arterial compliance analysis in dependence on transmural pressure
- Creator:
- Jiří Moudr, Jitka Svačinová, Eva Závodná, and Nataša Honzíková
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, tepny, krevní tlak, arteries, blood pressure, arterial compliance, finger arterial pressure, plethysmography, transmural arterial pressure, frequency characteristic, 14, and 612
- Language:
- English
- Description:
- The aim of this study was to obtain a detailed analysis of the relationship between the finger arterial compliance C [ml/mm Hg] and the arterial transmural pressure Pt [mm Hg]. We constructed a dynamic plethysmograph enabling us to set up a constant pressure Pcss [mm Hg] and a superimposed fast pressure vibration in the finger cuff (equipped with a source of infra-red light and a photoelectric sensor for the measurement of arterial volume). Pcss could be set on the required time interval in steps ranging between 30 and 170 mm Hg, and on sinusoidal pressure oscillation with an amplitude Pca (2 mm Hg) and a frequency f (20, 25, 30, 35, 40 Hz). At the same time continuous blood pressure BP was measured on the adjacent finger (Portapres). We described the volume dependence of a unitary arterial length on the time-varying transmural pressure acting on the arterial wall (externally Pcss+Pca.sin(2πf), internally BP) by a second-order differential equation for volume. This equation was linearized within a small range of selected BP. In the next step, a Fourier transform was applied to obtain the frequency characteristic in analytic form of a complex linear combination of frequency functions. While series of oscillations [Pca, f] were applied for each Pcss, the corresponding response of the plethysmogram was measured. Amplitude spectra were obtained to estimate coefficients of the frequency characteristic by regression analysis. We determined the absolute value: elastance E, and its inverse value: compliance (C=1/E). Then, C=C(Pt) was acquired by applying sequences of oscillations for different Pcss (and thus Pt) by the above-described procedure. This methodology will be used for the study of finger arterial compliance in different physiological and pathological conditions., J. Moudr, J. Svačinová, E. Závodná, N. Honzíková., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
68780. The vicissitudes of Chinese imperial art collections
- Creator:
- Olivová, Lucie
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Language:
- English
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public