446 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
SHARE Working Paper Series 57-2021: Time patterns of precautionary health behaviours during an easing phase of the COVID-19 pandemic in Europe
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
Lifetime-Management and Operational Lifetime Extension at Paks Nuclear Power Plant
The design life of the NPP PAKS WWER-440/213 units is 30 years. Formally the design life limits the
operational licence. The condition of the equipment after almost 20 years of operation is excellent. The lifetime
management activity of the Paks NPP provides a proper basis for the continuation of safe operation. The current
Hungarian Nuclear Regulations allow the extension of the operation licence of the NPP Units beyond the design life.
To prove the acceptability of continuation of operation the Licensee have to prepare a Licence Renewal Application not
later than 5 years before the expiration of the design lifetime. The Licence Renewal process based mainly on USNRC
approach taking into account the special features of the WWER-440/213 Units. Summary of the preconditions of the
Licence Renewal and the activity for the preparation of the operational lifetime extension are reported in the paper
Key Elements of the Ageing Management of the WWER-440/213 type Nuclear Power Plants
The owner’s intention of WWER-440/213 units in Central Europe is to keep the plants in operation as long as technically feasible and reasonable from business point of view. The preconditions of the long term operation and license renewal are the safety and good plant condition. The past and recent ageing management practices have to ensure the required condition and performance of the essential structures, systems and components. In the paper an overall picture of the long term operation of WWER-440/213 units is given. The review covers ageing of mechanical equipment, building structures and electrical equipment to. Key elements of the ageing management are identified and described. Basic issues of assessment of ageing of essential structures, systems and components, also the issues related to availability of design basis information and lacking environmental qualification are discussed. Reference examples typical for WWER-440/213 plants long term operation are given from Paks Nuclear Power Plant practice
β1 Integrin Signaling Maintains Human Epithelial Progenitor Cell Survival In Situ and Controls Proliferation, Apoptosis and Migration of Their Progeny
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