Kolmogorov complexity spectrum for use in analysis of UV-B radiation time series

We have used the Kolmogorov complexity and sample entropy measures to estimate the complexity of the UV-B radiation time series in the Vojvodina region (Serbia) for the period 1990-2007. We defined the Kolmogorov complexity spectrum and have introduced the Kolmogorov complexity spectrum highest value (KLM). We have established the UV-B radiation time series on the basis of their daily sum (dose) for seven representative places in this region using (i) measured data, (ii) data calculated via a derived empirical formula and (iii) data obtained by a parametric UV radiation model. We have calculated the Kolmogorov complexity (KL) based on the Lempel-Ziv Algorithm (LZA), KLM and Sample Entropy (SE) values for each time series. We have divided the period 1990-2007 into two sub-intervals: (a) 1990-1998 and (b)1999-2007 and calculated the KL, KLM and SE values for the various time series in these sub-intervals. It is found that during the period 1999-2007, there is a decrease in the KL, KLM and SE, comparing to the period 1990-1998. This complexity loss may be attributed to (i) the increased human intervention in the post civil war period causing increase of the air pollution and (ii) the increased cloudiness due to climate changes.Comment: 10 pages, 1 figure, 1 table. arXiv admin note: substantial text overlap with arXiv:1301.2039; This paper has been accepted in Modern Physics Letters B on Aug 14, 201

The Nature of the Warm/Hot Intergalactic Medium I. Numerical Methods, Convergence, and OVI Absorption

We perform a series of cosmological simulations using Enzo, an Eulerian adaptive-mesh refinement, N-body + hydrodynamical code, applied to study the warm/hot intergalactic medium. The WHIM may be an important component of the baryons missing observationally at low redshift. We investigate the dependence of the global star formation rate and mass fraction in various baryonic phases on spatial resolution and methods of incorporating stellar feedback. Although both resolution and feedback significantly affect the total mass in the WHIM, all of our simulations find that the WHIM fraction peaks at z ~ 0.5, declining to 35-40% at z = 0. We construct samples of synthetic OVI absorption lines from our highest-resolution simulations, using several models of oxygen ionization balance. Models that include both collisional ionization and photoionization provide excellent fits to the observed number density of absorbers per unit redshift over the full range of column densities (10^13 cm-2 <= N_OVI <= 10^15 cm^-2). Models that include only collisional ionization provide better fits for high column density absorbers (N_OVI > 10^14 cm^-2). The distribution of OVI in density and temperature exhibits two populations: one at T ~ 10^5.5 K (collisionally ionized, 55% of total OVI) and one at T ~ 10^4.5 K (photoionized, 37%) with the remainder located in dense gas near galaxies. While not a perfect tracer of hot gas, OVI provides an important tool for a WHIM baryon census.Comment: 22 pages, 21 figures, emulateapj, accepted for publication in Ap

Does Maturity Signals High Risk and High Return?

The objective of this study is to examine the interaction between firm maturity and firm growth opportunities over risk and its impact on returns. This study uses 135 firms listed in Indonesia Stock Exchange during 2010 to 2016 as sample which gives 945 as total observed data. This study conducts path analysis in term for hypothesis testing and finds that firm maturity has significant role to increase the risk which gives impact on increasing the returns. In context of Indonesian firms, the findings imply that mature firms will have higher risk and higher returns

Highly-Ionized Oxygen Absorbers in the Intergalactic Medium

Recent ultraviolet and X-ray observations of intergalactic OVI and OVII absorption systems along lines of sight to bright quasars have opened a new window onto the ``warm-hot intergalactic medium'' (WHIM). These systems appear to provide a significant reservoir for baryons in the local universe, and comparison to cosmological simulations suggests that their abundance roughly matches theoretical predictions. Here we use analytic arguments to elucidate the physical properties of the absorbers and their role in structure formation. We first show that if the absorbers result from structure-formation shocks, the observed column densities naturally follow from postshock-cooling models, if we include fast-cooling shocks as well as those that cannot cool within a Hubble time. In this case, the known OVI absorbers should show stronger OVII absorption than expected from collisional-ionization equilibrium (and much more than expected for photoionized systems). We then argue that higher-temperature shocks will be spatially associated with more massive virialized objects even well outside the virial radius. Thus the different oxygen ions will trace different structures; OVII absorbers are the most common because that ion dominates over a wide temperature range (corresponding to a large range in halo mass). If each dark-matter halo is surrounded by a network of shocks with total cross section a few times the size of the virialized systems, then we can reproduce the observed number densities of absorbers with plausible parameters. A simple comparison with simulations shows that these assumptions are reasonable, although the actual distribution of shocked gas is too complex for analytic models to describe fully. Our models suggest that these absorbers cannot be explained as a single-temperature phase.Comment: 13 pages, 12 figures, in press at MNRAS (minor modifications, conclusions unchanged

The new path of law : from theory of chaos to theory of law

From chaos to chaos theory, from the primordial perception of the world as disorderly to the scientific research of disorder a long distance has been covered. This path implies openness of mind and scientific boldness which connect mythological perceptions of the world with philosophical and scientific interpretations of phenomena throughout the world in a quite distinctive way resting on the creation of a model and application of computing. Owing to this, for the first time instead of asking What awaits us in the future? we can ask What can be done in the future? and get a reliable scientific answer to the question

The Large, Oxygen-Rich Halos of Star-Forming Galaxies Are A Major Reservoir of Galactic Metals

The circumgalactic medium (CGM) is fed by galaxy outflows and accretion of intergalactic gas, but its mass, heavy element enrichment, and relation to galaxy properties are poorly constrained by observations. In a survey of the outskirts of 42 galaxies with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope, we detected ubiquitous, large (150 kiloparsec) halos of ionized oxygen surrounding star-forming galaxies, but we find much less ionized oxygen around galaxies with little or no star formation. This ionized CGM contains a substantial mass of heavy elements and gas, perhaps far exceeding the reservoirs of gas in the galaxies themselves. It is a basic component of nearly all star-forming galaxies that is removed or transformed during the quenching of star formation and the transition to passive evolution.Comment: This paper is part of a set of three papers on circumgalactic gas observed with the Cosmic Origins Spectrograph on HST, to be published in Science, together with related papers by Tripp et al. and Lehner & Howk, in the November 18, 2011 edition. This version has not undergone final copyediting. Please see Science online for the final printed versio

The Low-z Intergalactic Medium. III. HI and Metal Absorbers at z<0.4

We conduct an ultraviolet (HST and FUSE) spectroscopic survey of HI (Lyman lines) and seven metal ions (OVI, NV, CIV, CIII, SiIV, SiIII, FeIII) in the low-redshift intergalactic medium (IGM) at z<0.4. We analyzed 650 Lya absorbers over redshift pathlength Delta z=5.27, detecting numerous absorbers: 83 OVI systems, 39 CIII, 53 SiIII, 24 CIV, 24 NV, and so on. Our survey yields distributions in column density and estimates of the IGM baryon content and metallicities of C, N, O in the IGM. In the low-z IGM, we have accounted for ~40% of the baryons: 30% in the photoionized Lya forest and 10% in the (T=10^5-6 K) warm-hot intergalactic medium (WHIM) traced by OVI. Statistical metallicities of C, N, O ions are consistent with the canonical (z=0) value of 10% solar, with considerable scatter. Improved statistics for weak OVI absorbers allows us to estimate Omega_WHIM/Omega_b=0.073+-0.008 down to logN_OVI=13.4. NV absorption is well-correlated with OVI and both ions show similarly steep power-law indices dN/dz N^-beta with beta_OVI beta_NV 2 while beta_HI=1.7. We conclude that OVI and NV are reliable tracers of the portion of the WHIM at T=10^5-6 K. CIV may be present in both collisional and photoionized phases; N_CIV correlates poorly with both N_HI and N_OVI and beta_HI<beta_CIV<beta_OVI. The ions CIII, SiIII, and SiIV are well correlated with HI and show patterns typical of photoionization. Adjacent ion stages of the same element (CIII/IV and SiIII/IV) provide useful constraints on the photoionization parameter, logU=-1.5+-0.5. Comparison of SiIV and CIV with high-z surveys shows a modest increase in line density, consistent with increasing IGM metallicity at recent epochs.Comment: Submitted to ApJ, 27 pages in ApJ format (figure and discussion added

Intergalactic Baryons in the Local Universe

Simulations predict that shocks from large-scale structure formation and galactic winds have reduced the fraction of baryons in the warm, photoionized phase (the Lya forest) from nearly 100% in the early universe to less than 50% today. Some of the remaining baryons are predicted to lie in the warm-hot ionized medium (WHIM) phase at T=10^5-10^7 K, but the quantity remains a highly tunable parameter of the models. Modern UV spectrographs have provided unprecedented access to both the Lya forest and potential WHIM tracers at z~0, and several independent groups have constructed large catalogs of far-UV IGM absorbers along ~30 AGN sight lines. There is general agreement between the surveys that the warm, photoionized phase makes up ~30% of the baryon budget at z~0. Another ~10% can be accounted for in collapsed structures (stars, galaxies, etc.). However, interpretation of the ~100 high-ion (OVI, etc) absorbers at z<0.5 is more controversial. These species are readily created in the shocks expected to exist in the IGM, but they can also be created by photoionization and thus not represent WHIM material. Given several pieces of observational evidence and theoretical expectations, I argue that most of the observed OVI absorbers represent shocked gas at T~300,000 K rather than photoionized gas at T<30,000 K, and they are consequently valid tracers of the WHIM phase. Under this assumption, enriched gas at T=10^5-10^6 K can account for ~10% of the baryon budget at z<0.5, but this value may increase when bias and incompleteness are taken into account and help close the gap on the 50% of the baryons still "missing".Comment: Invited review to appear in "Future Directions in Ultraviolet Spectroscopy", Oct 20-22, 2008, Annapolis, MD, M. E. Van Steenberg, ed. (April 2009). 8 pages, five figure

Chandra and Far Ultraviolet Spectroscopic Explorer Observations of z~0 Warm-Hot Gas Toward PKS 2155-304

The X-ray bright z=0.116 quasar PKS 2155-304 is frequently observed as a Chandra calibration source, with a total of 483 ksec of Low Energy Transmission Grating (LETG) exposure time accumulated through May 2006. Highly-ionized metal absorption lines, including numerous lines at z=0 and a putative OVIII K-alpha line at z=0.055, have been reported in past Chandra studies of this source. Using all available Chandra LETG spectra and analysis techniques developed for such z=0 X-ray absorption along other sightlines, we revisit these previous detections. We detect 4 absorption lines at >3\sigma significance (OVII K-alpha/beta, OVIII K-alpha, and NeIX K-alpha), with OVII K-alpha being a 7.3\sigma detection. The 1\sigma ranges of z=0 OVII column density and Doppler parameter are consistent with those derived for Mrk 421 and within 2\sigma of the Mrk 279 absorption. Temperatures and densities inferred from the relative OVII and other ionic column densities are found to be consistent with either the local warm-hot intergalactic medium or a Galactic corona. Unlike the local X-ray absorbers seen in other sightlines, a link with the low- or high-velocity far-ultraviolet OVI absorption lines cannot be ruled out. The z=0.055 OVIII absorption reported by Fang et al. is seen with 3.5\sigma confidence in the ACIS/LETG spectrum, but no other absorption lines are found at the same redshift.Comment: 11 pages, 9 figures; minor changes, accepted to Ap