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 O$-$C 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$\alpha$ 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

A római csontfaragványok kutatásának történeti áttekintése

A tanulmány rövid összegzése a legutóbbi 30 év csontfaragvány kutatásainak. Az utóbbi években körvonalazódtak azok a leletcsoportok, amelyek minden provinciában megtalálhatók, és mára meghatározhatóvá váltak azok a tárgytípusok, amelyeknél tovább éltek a római hódítás előtti lakosság hagyományai

Differential effects of caffeine on hair shaft elongation, matrix and outer root sheath keratinocyte proliferation, and TGF-beta2-/IGF-1-mediated regulation of hair cycle in male and female human hair follicles in vitro.

BACKGROUND: Caffeine reportedly counteracts the suppression of hair shaft production by testosterone in organ-cultured male human hair follicles (HFs). OBJECTIVES: We aimed at investigating the impact of caffeine a) on additional key hair growth parameters, b) on major hair growth-regulatory growth factors and c) on male versus female HFs in the presence of testosterone. METHODS: Microdissected male and female human scalp HFs were treated in serum-free organ culture for 120 h with testosterone alone (0,5 mug/ml) or in combination with caffeine (0.005-0.0005%), and effects on hair shaft elongation, HF cycling (i.e. anagen-catagen transition), hair matrix keratinocyte proliferation and expression of a key catagen inducer, transforming growth factor beta2 (TGF-beta2), and anagen-prolonging insulin-like growth factor 1 (IGF-1) were evaluated by quantitative (immuno-) histomorphometry. Caffeine effects were further investigated in human outer root sheath keratinocytes (ORSK). RESULTS: Caffeine enhanced hair shaft elongation, prolonged anagen duration and stimulated hair matrix keratinocyte proliferation. Female HFs showed higher sensitivity to caffeine compared to male HFs. Caffeine counteracted testosterone-enhanced TGF-beta2 protein expression in male HFs. In female HFs, testosterone failed to induce TGF-beta2 expression, while caffeine reduced it. In male and female HFs, caffeine enhanced IGF-1 protein expression. In ORSK, caffeine stimulated cell proliferation, inhibited apoptosis/necrosis, up-regulated IGF-1 gene expression and protein secretion, while TGF-beta2 protein secretion was down-regulated. CONCLUSIONS: This study reveals new growth-promoting effects of caffeine on human hair follicles of both genders at different (molecular, cellular and organ) levels. This article is protected by copyright. All rights reserved

Regulation of TRPC6 ion channels in podocytes — Implications for focal segmental glomerulosclerosis and acquired forms of proteinuric diseases

The glomerular filtration barrier is a highly specialized tri-layer structure with unique functional properties. Podocyte dysfunction and cytoskeletal disorganization leads to disruption of the slit diaphragma, and proteinuria. Inflammatory diseases involving the kidney as well as inherited podocytopathies or diabetic nephropathy cause injury of the podocyte network. Focal segmental glomerulosclerosis (FSGS) is a pathologic entity that is a common cause of nephrotic syndrome with severe proteinuria in both adults and children. Several causative genes have been identified in the pathogenesis of FSGS. Mutations of the transient receptor potential canonical-6 (TRPC6), a non-selective cation channel that is directly activated by diacylglycerol (DAG), cause a particularly aggressive form of FSGS. Angiotensin II, acting through its AT1 receptor, plays a critical role in generation of proteinuria and progression of kidney injury in a number of kidney diseases, including FSGS. Mounting evidence suggest the central role of TRPC6 and perhaps other TRPC channels in the pathogenesis of FSGS as well as of acquired forms of proteinuria such as diabetic nephropathy or hypertension. Identification of signaling pathways downstream of TRPC6 may provide novel targets for the treatment of proteinuria and prevent progression of podocyte injury