Atmospheric multiple scattering of fluorescence and Cherenkov light emitted by extensive air showers

Atmospheric scattering of light emitted by an air shower not only attenuates direct fluorescence light from the shower, but also contributes to the observed shower light. So far only direct and singly-scattered Cherenkov photons have been taken into account in routine analyses of the observed optical image of air showers. In this paper a Monte Carlo method of evaluating the contribution of multiply scattered light to the optical air shower image is presented, as well as results of simulations and a parameterization of scattered light contribution to measured shower signal.Comment: 27 pages, 18 figures, accepted for publication in NIM

Morphometric characteristics of the small and large intestines of Mus musculus during postnatal development

The objective of this study was to investigate the size of the small and large intestine in postnatal development of Mus musculus mice. The gut was obtained from 2-, 4-, 6-, and 12-week-old animals. The morphometric analysis was performed at microscopic level. Measurements and calculations included dimensions of villi (height, diameter) and their number per 1 mm2 surface area in the proximal, middle, and distal section of the small intestine, as well as the length and surface area (external and internal) of the small and large intestines. To find the allometric relationship between the size of the small and large intestines and body mass, reduced major axis regression was applied. The length and surface area of both intestinal segments gradually increased with age. The increase in the internal surface area of the small intestine was the result of lengthening of the intestine and increasing diameter of the villi in its proximal and middle sections. No increase in villus height during the studied period was detected. A marked increase in the size of the intestinal segments was observed between the 2nd and 4th weeks of life, when the length doubled and the surface area tripled in size. Allometric analysis revealed that the increase in length and internal surface area of the small and large intestines was more rapid than the body mass increase during the weaning period, while it was not different from isometry after the weaning. In conclusion, the greatest changes in the structure and size of the small and large intestines of mice occurred in the weaning period. During this period these two segments of intestine grew faster than the rest of the body and reached adult proportions. (Folia Morphol 2011; 70, 4: 252–259

Nutritional modulators of neuropsychiatric dysfunction

This review article gathers evidence on the potential relationship between dietary intake of w3 polyunsaturated fatty acids (w3 PUFAs) and mental function. Several pieces of evidence that w3 PUFAs influence affective and cognitive function are presented. Although published data and results available in the field remain limited and sometimes ambiguous, they have shed a new light on the role of proper diet in general, w3 PUFAs in particular, in many mental disorders and dysfunctions, including depression and cognitive decline in aging. The analysis of the influence of fatty acids on human health allows us to formulate a new, more holistic approach to both prevention and treatment of psychological disorders and dysfunctions. What is more, it appears that w3 PUFAs have a beneficial influence on mental function in healthy people as well. The currently available data concerning the influence of fatty acids on behaviour and mental function are still insufficient and suffer so far from lack of standard determination of background, intermediairy and endpoint omega-6/3 ratios in plasma lipids of patients involved in both epidemiological and intervention studies. There is a great need for further refined trials in the field

Critical exponents and phase transition in gold nuclei fragmentation at energies 10.6 and 4.0 GeV/nucleon

An attempt to extract critical exponents gamma, beta and tau from data on gold nuclei fragmentation due to interactions with nuclear emulsion at energies 4.0 A GeV and 10.6 A GeV is presented. Based on analysis of Campi's 2nd charge moments, two subsets of data at each energy are selected from the inclusive data, corresponding to 'liquid' and 'gas' phases. The extracted values of critical exponents from the selected data sets are in agreement with predictions of 'liquid-gas' model of phase transition.Comment: 21 pages, 15 figure

Characterisation of solid particles emitted from diesel and petrol engines as a contribution to the determination of the origin of carbonaceous particles in urban aerosol

Solid particles emitted from diesel and petrol engines were studied using a scanning electron microscope fitted with an energy dispersive spectrometer. The soot emitted from different engines under different operating conditions differed in particle size, and the form and size of aggregates. Identification of the soot particles emitted from diesel or petrol engines in urban aerosol based on their size and morphology was found to be impossible

On a possible photon origin of the most-energetic AGASA events

In this work the ultra high energy cosmic ray events recorded by the AGASA experiment are analysed. With detailed simulations of the extensive air showers initiated by photons, the probabilities are determined of the photonic origin of the 6 AGASA events for which the muon densities were measured and the reconstructed energies exceeded 10^20 eV. On this basis a new, preliminary upper limit on the photon fraction in cosmic rays above 10^20 eV is derived and compared to the predictions of exemplary top-down cosmic-ray origin models.Comment: 3 pages, 1 figure, 2 tables; presented at XIII ISVHECRI, Pylos, Greec

Simulation of Ultra-High Energy Photon Propagation in the Geomagnetic Field

The identification of primary photons or specifying stringent limits on the photon flux is of major importance for understanding the origin of ultra-high energy (UHE) cosmic rays. We present a new Monte Carlo program allowing detailed studies of conversion and cascading of UHE photons in the geomagnetic field. The program named PRESHOWER can be used both as an independent tool or together with a shower simulation code. With the stand-alone version of the code it is possible to investigate various properties of the particle cascade induced by UHE photons interacting in the Earth's magnetic field before entering the Earth's atmosphere. Combining this program with an extensive air shower simulation code such as CORSIKA offers the possibility of investigating signatures of photon-initiated showers. In particular, features can be studied that help to discern such showers from the ones induced by hadrons. As an illustration, calculations for the conditions of the southern part of the Pierre Auger Observatory are presented.Comment: 41 pages, 9 figures, added references in introduction, corrected energy in row 1 of Table 3, extended caption of Table

Characteristics of geomagnetic cascading of ultra-high energy photons at the southern and northern sites of the Pierre Auger Observatory

Cosmic-ray photons above 10^19 eV can convert in the geomagnetic field and initiate a preshower, i.e. a particle cascade before entering the atmosphere. We compare the preshower characteristics at the southern and northern sites of the Pierre Auger Observatory. In addition to a shift of the preshower patterns on the sky due to the different pointing of the local magnetic field vectors, the fact that the northern Auger site is closer to the geomagnetic pole results in a different energy dependence of the preshower effect: photon conversion can start at smaller energies, but large conversion probabilitites (>90%) are reached for the whole sky at higher energies compared to the southern Auger site. We show how the complementary preshower features at the two sites can be used to search for ultra-high energy photons among cosmic rays. In particular, the different preshower characteristics at the northern Auger site may provide an elegant and unambiguous confirmation if a photon signal is detected at the southern site.Comment: 25 pages, 14 figures, minor changes, conclusions unchanged, Appendix A replaced, accepted by Astroparticle Physic

Two-proton small-angle correlations in central heavy-ion collisions: a beam-energy and system-size dependent study

Small-angle correlations of pairs of protons emitted in central collisions of Ca + Ca, Ru + Ru and Au + Au at beam energies from 400 to 1500 MeV per nucleon are investigated with the FOPI detector system at SIS/GSI Darmstadt. Dependences on system size and beam energy are presented which extend the experimental data basis of pp correlations in the SIS energy range substantially. The size of the proton-emitting source is estimated by comparing the experimental data with the output of a final-state interaction model which utilizes either static Gaussian sources or the one-body phase-space distribution of protons provided by the BUU transport approach. The trends in the experimental data, i.e. system-size and beam energy dependences, are well reproduced by this hybrid model. However, the pp correlation function is found rather insensitive to the stiffness of the equation of state entering the transport model calculations.Comment: 9 pages, 8 figures, accepted at Eur. Phys. Journ.