The baryon density at z=0.9-1.9 - Tracing the warm-hot intergalactic medium with broad Lyman alpha absorption

We present an analysis of the Lyman alpha forests of five quasar spectra in the near UV. Properties of the intergalactic medium (IGM) at an intermediate redshift interval (0.9 < z < 1.9) are studied. The amount of baryons in the diffuse photoionised IGM and the warm-hot intergalactic medium (WHIM) are traced to get constraints on the redshift evolution of the different phases of the intergalactic gas. The baryon density of the diffuse IGM is determined with photoionisation calculations under the assumption of local hydrostatic equilibrium. We assume that the gas is ionised by a metagalactic background radiation with a Haardt & Madau (2001) spectrum. The WHIM is traced with broad Lyman alpha (BLA) absorption. The properties of a number of BLA detections are studied. Under the assumption of collisional ionisation equilibrium a lower limit to the baryon density could be estimated. It is found that the diffuse photoionised IGM contains at least 25% of the total baryonic matter at redshifts 1 < z < 2. For the WHIM a lower limit of 2.4% could be determined. Furthermore the data indicates that the intergalactic gas is in a state of evolution at z=1.5. We confirm that a considerable part of the WHIM is created between z=1 and z=2.Comment: 6 pages, 1 figure, accepted for publication in A&

Соціокультурні аспекти розвитку системи дитячо-юнацького туризму (на прикладі Харківської обласної станції юних туристів)

Метою статті є аналіз соціокультурних аспектів сучасного розвитку системи дитячо-юнацького туризму, висвітлення досвіду роботи Харківської обласної станції юних туристів в зазначеному напрямку. Аналіз досліджень і публікацій. Дослідженню питань розвитку системи дитячо-юнацького туризм

Conditions of the Development of Logistic Centers in Poland in the Context of European States Experiences

The article is, for the most part, the aftermath of his own examinations carried out in years 2007-2010 and concerning logistic centers development conditioning.Artykuł jest w znacznej mierze pokłosiem badań własnych autora przeprowadzonych w latach: 2007-2010 dotyczących uwarunkowań rozwoju centrów logistycznych

Nonlocal nonlinear phononics

Nonlinear phononics relies on the resonant optical excitation of infrared-active lattice vibrations to induce targeted structural deformations in solids. This form of dynamical crystal structure design has been applied to control the functional properties of many complex solids, including magnetic materials, superconductors and ferroelectrics. However, phononics has so far been restricted to protocols in which structural deformations occur within the optically excited volume, sometimes resulting in unwanted heating. Here, we extend nonlinear phononics to propagating polaritons, spatially separating the functional response from the optical drive. We use mid-infrared optical pulses to resonantly drive a phonon at the surface of ferroelectric LiNbO3. Time-resolved stimulated Raman scattering reveals that the ferroelectric polarization is reduced over the entire 50 µm depth of the sample, far beyond the micrometre depth of the evanescent phonon field. We attribute this effect to the anharmonic coupling between the driven mode and a polariton that propagates into the material. For high excitation amplitudes, we reach a regime in which the ferroelectric polarization is reversed, as revealed by a sign change in the Raman tensor coefficients of all the polar modes

An HST/COS legacy survey of high-velocity ultraviolet absorption in the Milky Way's circumgalactic medium and the Local Group

To characterize the absorption properties of this circumgalactic medium (CGM) and its relation to the LG we present the so-far largest survey of metal absorption in Galactic high-velocity clouds (HVCs) using archival ultraviolet (UV) spectra of extragalactic background sources. The UV data are obtained with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST) and are supplemented by 21 cm radio observations of neutral hydrogen. Along 270 sightlines we measure metal absorption in the lines of SiII, SiIII, CII, and CIV and associated HI 21 cm emission in HVCs in the velocity range |v_LSR|=100-500 km s^-1. With this unprecedented large HVC sample we were able to improve the statistics on HVC covering fractions, ionization conditions, small-scale structure, CGM mass, and inflow rate. For the first time, we determine robustly the angular two point correlation function of the high-velocity absorbers, systematically analyze antipodal sightlines on the celestial sphere, and compare the absorption characteristics with that of Damped Lyman alpha absorbers (DLAs) and constrained cosmological simulations of the LG. Our study demonstrates that the Milky Way CGM contains sufficient gaseous material to maintain the Galactic star-formation rate at its current level. We show that the CGM is composed of discrete gaseous structures that exhibit a large-scale kinematics together with small-scale variations in physical conditions. The Magellanic Stream clearly dominates both the cross section and mass flow of high-velocity gas in the Milky Way's CGM. The possible presence of high-velocity LG gas underlines the important role of the local cosmological environment in the large-scale gas-circulation processes in and around the Milky Way (abridged).Comment: 37 pages, 25 figures, 8 tables, accepted for publication in A&

Nitrogen-deficient and iron-rich associated absorbers with oversolar metallicities towards the quasar HE0141-3932

HE0141-3932 (zem=1.80) is a bright blue radio-quite quasar which reveals an emission line spectrum with an unusually weak Ly-alpha line. In addition, large redshift differences (Delta z=0.05) are observed between high ionization and low ionization emission lines. Absorption systems identified at z=1.78, 1.71, and 1.68 show mild oversolar metallicities (Z ~= 1-2Zsolar) and can be attributed to the associated gas clouds ejected from the circumnuclear region. The joint analysis of the emission and absorption lines leads to the conclusion that this quasar is seen almost pole-on. Its apparent luminosity may be Doppler boosted by ~10 times. The absorbing gas shows high abundance of Fe, Mg, and Al ([Fe, Mg, Al/C] ~= 0.15+/-0.10) along with underabundance of N ([N/C]<=-0.5). This abundance pattern is at variance with current chemical evolution models of QSOs predicting [N/C]>0 and [Fe/C]<0 at Z ~ Zsolar. Full details of this work are given in Reimers et al. (2005).Comment: 2 pages, to appear in the Proceed. of IAU Symp.228 "From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution", eds. V.Hill, P.Francois and F.Prima

Fractal Dimensions in Perceptual Color Space: A Comparison Study Using Jackson Pollock's Art

The fractal dimensions of color-specific paint patterns in various Jackson Pollock paintings are calculated using a filtering process which models perceptual response to color differences (\Lab color space). The advantage of the \Lab space filtering method over traditional RGB spaces is that the former is a perceptually-uniform (metric) space, leading to a more consistent definition of ``perceptually different'' colors. It is determined that the RGB filtering method underestimates the perceived fractal dimension of lighter colored patterns but not of darker ones, if the same selection criteria is applied to each. Implications of the findings to Fechner's 'Principle of the Aesthetic Middle' and Berlyne's work on perception of complexity are discussed.Comment: 21 pp LaTeX; two postscript figure

HE 0141-3932: a bright QSO with an unusual emission line spectrum and associated absorption

HE 0141-3932 (zem = 1.80) is a bright blue radio-quite quasar with an unusually weak Ly-alpha emission line. Large redshift differences (Delta z = 0.05) are observed between high ionization and low ionization emission lines. Absorption systems identified at zabs = 1.78, 1.71, and 1.68 show mild oversolar metallicities (Z ~= 1-2Zsolar) and can be attributed to the associated gas clouds ejected from the circumnuclear region. The joint analysis of the emission and absorption lines leads to the conclusion that this quasar is seen almost pole-on. Its apparent luminosity may be Doppler boosted by ~10 times. The absorbing gas shows a high abundance of Fe, Mg and Al ([Fe, Mg, Al/C] ~= 0.15 +/- 0.10) along with underabundance of N ([N/C] <= -0.5). This abundance pattern is at variance with current chemical evolution models of QSOs predicting [N/C] >= 0$ and [Fe/C] < 0 at Z ~ Zsolar.Comment: 12 pages, 6 figures, accepted for publication in A&

The modelling cycle for collective animal behaviour

Collective animal behaviour is the study of how interactions between individuals produce group level patterns, and why these interactions have evolved. This study has proved itself uniquely interdisciplinary, involving physicists, mathematicians, engineers as well as biologists. Almost all experimental work in this area is related directly or indirectly to mathematical models, with regular movement back and forth between models, experimental data and statistical fitting. In this paper, we describe how the modelling cycle works in the study of collective animal behaviour. We classify studies as addressing questions at different levels or linking different levels, i.e. as local, local to global, global to local or global. We also describe three distinct approaches—theory-driven, data-driven and model selection—to these questions. We show, with reference to our own research on species across different taxa, how we move between these different levels of description and how these various approaches can be applied to link levels together