379 research outputs found
Abstract composition rule for relativistic kinetic energy in the thermodynamical limit
We demonstrate by simple mathematical considerations that a power-law tailed
distribution in the kinetic energy of relativistic particles can be a limiting
distribution seen in relativistic heavy ion experiments. We prove that the
infinite repetition of an arbitrary composition rule on an infinitesimal amount
leads to a rule with a formal logarithm. As a consequence the stationary
distribution of energy in the thermodynamical limit follows the composed
function of the Boltzmann-Gibbs exponential with this formal logarithm. In
particular, interactions described as solely functions of the relative
four-momentum squared lead to kinetic energy distributions of the
Tsallis-Pareto (cut power-law) form in the high energy limit.Comment: Submitted to Europhysics Letters. LaTeX, 3 eps figure
The contact binary VW Cephei revisited: surface activity and period variation
Context. Despite the fact that VW Cephei is one of the well-studied contact
binaries in the literature, there is no fully consistent model available that
can explain every observed property of this system.
Aims. Our motivation is to obtain new spectra along with photometric
measurements, to analyze what kind of changes may have happened in the system
in the past two decades, and to propose new ideas for explaining them.
Methods. For the period analysis we determined 10 new times of minima from
our light curves, and constructed a new OC diagram of the system. Radial
velocities of the components were determined using the cross-correlation
technique. The light curves and radial velocities were modelled simultaneously
with the PHOEBE code. All observed spectra were compared to synthetic spectra
and equivalent widths of the H line were measured on their differences.
Results. We have re-determined the physical parameters of the system
according to our new light curve and spectral models. We confirm that the
primary component is more active than the secondary, and there is a correlation
between spottedness and the chromospheric activity. We propose that flip-flop
phenomenon occurring on the primary component could be a possible explanation
of the observed nature of the activity. To explain the period variation of VW
Cep, we test two previously suggested scenarios: presence of a fourth body in
the system, and the Applegate-mechanism caused by periodic magnetic activity.
We conclude that although none of these mechanisms can be ruled out entirely,
the available data suggest that mass transfer with a slowly decreasing rate
gives the most likely explanation for the period variation of VW Cep.Comment: 13 pages, 18 figures, 9 tables, accepted for publication in Astronomy
and Astrophysic
NDVI as a Proxy for Estimating Sedimentation and Vegetation Spread in Artificial Lakes — Monitoring of Spatial and Temporal Changes by Using Satellite Images Overarching Three Decades
Observing wetland areas and monitoring changes are crucial to understand hydrological and ecological processes. Sedimentation-induced vegetation spread is a typical process in the succession of lakes endangering these habitats. We aimed to survey the tendencies of vegetation spread of a Hungarian lake using satellite images, and to develop a method to identify the areas of risk. Accordingly, we performed a 33-year long vegetation spread monitoring survey. We used the Normalized Difference Vegetation Index (NDVI) and the Modified Normalized Difference Water Index
(MNDWI) to assess vegetation and open water characteristics of the basins. We used these spectral indices to evaluate sedimentation risk of water basins combined with the fact that the most abundant plant species of the basins was the water caltrop (Trapa natans) indicating shallow water. We proposed a 12-scale Level of Sedimentation Risk Index (LoSRI) composed from vegetation cover data derived from
satellite images to determine sedimentation risk within any given water basin. We validated our results with average water basin water depth values, which showed an r = 0.6 (p < 0.05) correlation. We also pointed on the most endangered locations of these sedimentation-threatened areas, which can provide crucial information for management planning of water directorates and management organizations
Cross-Cultural Adaptation and Lingual Validation of the Beliefs about Medicines Questionnaire (BMQ)-Specific for Cholesterol Lowering Drugs in the Visegrad Countries
The goal of this study was to translate the Beliefs about Medicines Questionnaire—Specific
(BMQ-Specific) for cholesterol-lowering drugs, into the Hungarian, Slovak, Czech and Polish
languages and test their reliability with statistical methods. For this purpose, Cronbach’s alpha,
confirmatory and exploratory factor analyses were conducted. The analyses included 235 Czech,
205 Hungarian, 200 Polish, and 200 Slovak respondents, all of whom were taking cholesterol-lowering
drugs. The translations from English into the target languages were always done by two independent
translators. As part of the validation process these translations were pilot tested and after the necessary
alterations, they were translated back into English by a third translator. After the approval by the
creator of the questionnaire, nationwide surveys were conducted in all four countries. The results of the
confirmatory factor analysis were exceptionally good for the Czech and Slovak translations, while the
Polish and Hungarian translations marginally crossed the predetermined thresholds. With the
exception of a single Polish question, the results of the exploratory factor analysis were deemed
acceptable. The translated versions of BMQ-Specific are reliable and valid tools to assess patients’
beliefs about medication, especially medication adherence among patients taking cholesterol-lowering
medication. A comparison between the four countries with this questionnaire is now possible
The cultural and geopolitical dimensions of nation-building in the Ukraine
Ukraine belongs among those young countries where the beginnings of democratisation and nation-building approximately coincided. While the development of nation states in Central Europe was usually preceded by the development of nations, the biggest dilemma in the Ukraine is whether a nation-state programme — parallel to the aim of state-building — is able to bring unfinished nation-building to completion. Ukraine sways between the EU and Russia with enormous amplitude. The alternating orientation between the West and the East can be ascribed to superpower ambitions reaching beyond Ukraine. Eventually, internal and external determinants are intertwined and mutually interact with one another. The aim of the paper is to explain the dilemmas arising from identity problems behind the Ukraine’s internal and external orientation
Development and validation of two self-reported tools for insulin resistance and hypertension risk assessment in a European cohort : the Feel4Diabetes-study
Early identification of type 2 diabetes mellitus (T2DM) and hypertension (HTN) risk may improve prevention and promote public health. Implementation of self-reported scores for risk assessment provides an alternative cost-effective tool. The study aimed to develop and validate two easy-to-apply screening tools identifying high-risk individuals for insulin resistance (IR) and HTN in a European cohort. Sociodemographic, lifestyle, anthropometric and clinical data obtained from 1581 and 1350 adults (baseline data from the Feel4Diabetes-study) were used for the European IR
and the European HTN risk assessment index respectively. Body mass index, waist circumference, sex, age, breakfast consumption, alcohol, legumes and sugary drinks intake, physical activity and sedentary behavior were significantly correlated with Homeostatic Model Assessment of IR (HOMA-IR) and/or HTN and incorporated in the two models. For the IR index, the Area Under the Curve (AUC), sensitivity and specificity for identifying individuals above the 75th and 95th of HOMA-IR percentiles were 0.768 (95%CI: 0.721–0.815), 0.720 and 0.691 and 0.828 (95%CI: 0.766–0.890),
0.696 and 0.778 respectively. For the HTN index, the AUC, sensitivity and specificity were 0.778 (95%CI: 0.680–0.876), 0.667 and 0.797. The developed risk assessment tools are easy-to-apply, valid, and low-cost, identifying European adults at high risk for developing T2DM or having HTN
- …