Correlations in large pTp_{T} processes in parton models

We calculate the two-particle distribution and the associated multiplicity for large $p_{T}$ region in the framework of the parton models. We find that it is possible to construct a model being able to fit quite well a large amount of data on the two-particle level. The model should possess the following properties: a) the hard scattering cross-section should be independent of energy at fixed $p_{T}$, b) both quasi-exclusive (single-jet) and inclusive (double-jet) components must be present with the cross-section for the double-jet process at least one order of magnitude larger than that for the single-jet process, c) the mean transverse momentum in the jet fragmentation should be of the order of 630 MeV, d) the jet structure function should be damped like (1 - x)$^{2}$ for x $\to$ 1

Single-particle inclusive distribution at large pT_{T} in parton models

The predictions of parton models for the single-particle distribution in the large p$_{T}$ region are analysed. An explicit expression for the slope B in the formula $E\frac{d\sigma }{d^{3}p}=\frac{c}{p_{T}^{N}}e^{-Bx_{T}}$ is derived. It is shown that the weak rapidity dependence of B, observed at ISR implies the hard scattering cross-section $\frac{d\sigma }{dt}$ to be approximately independent of energy at fixed p$_{T}$

Truncated moments of parton distributions

We derive evolution equations satisfied by moments of parton distributions when the integration over the Bjorken variable is restricted to a subset (x_0 <= x <= 1) of the allowed kinematical range 0<= x<= 1. The corresponding anomalous dimensions turn out to be given by a triangular matrix which couples the N--th truncated moment with all (N + K)--th truncated moments with integer K >= 0. We show that the series of couplings to higher moments is convergent and can be truncated to low orders while retaining excellent accuracy. We give an example of application to the determination of alpha_s from scaling violations.Comment: 11 pages, no figures, latex. Final version, to be published in Phys. Lett. B. A few typos corrected; derivation of eq.(9) improve

Oxysterols Increase Inflammation, Lipid Marker Levels and Reflect Accelerated Endothelial Dysfunction in Experimental Animals

Objective. Oxidized cholesterol derivatives are thought to exert atherogenic effect thus adversely affecting vascular endothelium. The aim of the study was to assess the effect of 5α,6α-epoxycholesterol on experimentally induced hypercholesterolemia in rabbits, and the levels of homocysteine (HCY), asymmetric dimethylarginine (ADMA), paraoxonase-1 (PON-1), and inflammatory parameters (IL-6, TNF-α, CRP). Material and methods. The rabbits were divided into 3 groups, 8 animals each, and fed with basic fodder (C), basic fodder plus cholesterol (Ch) or basic fodder plus 5α,6α-epoxycholesterol, and unoxidized cholesterol (ECh). Serum concentrations of studied parameters were determined at 45-day intervals. The study was continued for six months. Results. We demonstrated that adding 5α,6α-epoxycholesterol to basic fodder significantly affected lipid status of the experimental animals, increasing total cholesterol and LDL cholesterol levels, as well as HCY and ADMA levels, whilst leaving the PON-1 activity unaffected. Additionally, the ECh group presented with significantly higher concentrations of inflammatory biomarkers (IL-6, TNF-α, and CRP). In the Ch group, lower yet significant (as compared to the C group) changes of levels of studied parameters were observed. Conclusion. Exposure of animals with experimentally induced hypercholesterolemia to 5α,6α-epoxycholesterol increases dyslipidaemia, endothelial dysfunction, and inflammatory response

Rodzice–szkoła i szkoła–rodzice: wzajemne oczekiwania

Artykuł z numeru 1/2012 internetowego czasopisma edukacyjnego ORE "Trendy

Oxysterols Increase Inflammation, Lipid Marker Levels and Reflect Accelerated Endothelial Dysfunction in Experimental Animals

Objective. Oxidized cholesterol derivatives are thought to exert atherogenic effect thus adversely affecting vascular endothelium. The aim of the study was to assess the effect of 5α,6α-epoxycholesterol on experimentally induced hypercholesterolemia in rabbits, and the levels of homocysteine (HCY), asymmetric dimethylarginine (ADMA), paraoxonase-1 (PON-1), and inflammatory parameters (IL-6, TNF-α, CRP). Material and methods. The rabbits were divided into 3 groups, 8 animals each, and fed with basic fodder (C), basic fodder plus cholesterol (Ch) or basic fodder plus 5α,6α-epoxycholesterol, and unoxidized cholesterol (ECh). Serum concentrations of studied parameters were determined at 45-day intervals. The study was continued for six months. Results. We demonstrated that adding 5α,6α-epoxycholesterol to basic fodder significantly affected lipid status of the experimental animals, increasing total cholesterol and LDL cholesterol levels, as well as HCY and ADMA levels, whilst leaving the PON-1 activity unaffected. Additionally, the ECh group presented with significantly higher concentrations of inflammatory biomarkers (IL-6, TNF-α, and CRP). In the Ch group, lower yet significant (as compared to the C group) changes of levels of studied parameters were observed. Conclusion. Exposure of animals with experimentally induced hypercholesterolemia to 5α,6α-epoxycholesterol increases dyslipidaemia, endothelial dysfunction, and inflammatory response

Small-x Resummation and HERA Structure Function Data

We apply our systematic NLO small x resummation of singlet splitting functions to the scaling violations of structure functions and compare the results with data. We develop various theoretical tools which are needed in order to relate resummed parton distributions to measurable structure functions, and we present results from a variety of fits to HERA data for the structure functions F_2 and F_L using the resummation. The behaviour of the singlet splitting functions at small x and fixed Q^2 is effectively parametrized as x^{-lambda}. We find that, for lambda small or negative, the resummed description of scaling violations may be phenomenologically as good as or even better than the standard next-to-leading order treatment. However, the best fit gluon density and value of alpha_s can be significantly modified by the resummation.Comment: 40 pages, 15 figures. Final version, to be published in Nucl. Phys. B. Typos corrected in eq. 4.5 and eq. 4.20 and in caption to fig.

The high energy cosmic ray spectrum from relic particle decay

It has been speculated that the recently detected ultra-high energy cosmic rays may originate from the decays of relic particles with mass of order $10^{12}$ GeV clustered in the halo of our Galaxy. This hypothesis can be tested through forthcoming measurements of the spectra of both high energy cosmic nucleons and neutrinos, which are determined in this model by the physics of QCD fragmentation, with no astrophysical uncertainties. We evolve fragmentation spectra measured at LEP energies up to the scale of the decaying particle mass by numerical solution of the DGLAP equations. This enables incorporation of the effects of supersymmetry on the development of the cascade and we also allow for decays into many-particle states. The calculated spectral shape agrees well with present cosmic ray data beyond the Greisen-Zatsepin-Kuzmin energy.Comment: 30 pages (revtex), 12 figures (eps); Small revisions; Accepted for publicatio

Study on Influence of the Firefighter Clothing Structure on its Protective Performance

W artykule omówiono kryteria oceny właściwości ochronnych ubiorów strażackich oparte o przewidywany stopień oparzenia i wykorzystanie temperatury powierzchniowych warstw skóry. Przedstawiono metody oceny tych właściwości bazujące na pomiarach temperatury przeprowadzanych na manekinach i specjalnie zaprojektowanych stanowiskach pomiarowych wykorzystujących próbki ubiorów ochronnych. Szczególną uwagę zwrócono na metodę opartą o symulację numeryczna procesów wymiany ciepła i wilgoci w ubiorach ochronnych warstwach powietrznych oddzielających jego poszczególne warstwy oraz w skórze. Omówiono zalety i wady zarówno metod eksperymentalnych, jak i teoretycznej oceny właściwości ochronnych ubioru. Krótko streszczono rodzaje materiałów stosowanych na warstwy ubioru ochronnego i ich właściwości cieplne, radiacyjne i dyfuzyjne. Na podstawie symulacji numerycznej różnych sposobów wymiany ciepła w ubiorze ochronnym wykazano, że największą rolę odgrywa w niej przewodzenie ciepła i promieniowanie cieplne. Przeprowadzano symulacje numeryczne przepływu ciepła przez trzy ubiory ochronne wykonane z warstw różnych materiałów. Wykazano, że ubiory te różnią się, przy zadanym obciążeniu cieplnym, zarówno przewidywanym wzrostem temperatury przypowierzchniowych warstw skóry jak stopniem oparzenia. Zbadano również wpływ grubości szczelin powietrznych między warstwami ubioru oraz między wewnętrzną powierzchnią ubioru i skórą wykazując istotny wpływ tej ostatniej szczeliny na przewidywany stopień oparzenia.Criteria for evaluation of protective properties of firefighters clothing were presented in the paper. They were based on a degree of predicted skin burns and determination of temperature of the skin surface layers. Methods of the skin temperature measurements using mannequins and specially designed experimental stands containing samples of the protective clothing were described. Special attention was directed toward numerical simulation of heat and moisture transfer across layers of the protective clothing as well as via the air spaces separating them and the human skin. Advantages and disadvantages of the experimental and theoretical methods were briefly discussed. Types of textiles used for the separate layers of the protective clothing together with their thermal radiative and diffusive properties were presented. Numerical simulations indicate that heat conduction and thermal radiation play the most important role in heat transfer across the protective clothing. The numerical simulations were also carried out for three kinds of the protective clothing made from layers of different textiles. It was shown that these clothing differ in the predicted skin temperature values and burn degree for the same thermal load applied. Effect of changing thickness of the air spaces between textile layers and the skin on the burn degree was also studied. It was proved that the latter air space exerts significant influence on the predicted burn degree