Cosmology with Strong Lensing Systems

In this paper, we assemble a catalog of 118 strong gravitational lensing systems from SLACS, BELLS, LSD and SL2S surveys and use them to constrain the cosmic equation of state. In particular we consider two cases of dark energy phenomenology: $XCDM$ model where dark energy is modeled by a fluid with constant $w$ equation of state parameter and in Chevalier - Polarski - Linder (CPL) parametrization where $w$ is allowed to evolve with redshift: $w(z) = w_0 + w_1 \frac{z}{1+z}$. We assume spherically symmetric mass distribution in lensing galaxies, but relax the rigid assumption of SIS model in favor to more general power-law index $\gamma$, also allowing it to evolve with redshifts $\gamma(z)$. Our results for the $XCDM$ cosmology show the agreement with values (concerning both $w$ and $\gamma$ parameters) obtained by other authors. We go further and constrain the CPL parameters jointly with $\gamma(z)$. The resulting confidence regions for the parameters are much better than those obtained with a similar method in the past. They are also showing a trend of being complementary to the supernova Ia data. Our analysis demonstrates that strong gravitational lensing systems can be used to probe cosmological parameters like the cosmic equation of state for dark energy. Moreover, they have a potential to judge whether the cosmic equation of state evolved with time or not.Comment: 7 figures, 2 table

Gravitational Lenses as Standard Rulers in Cosmology

The accelerating expansion of the Universe is a great challenge for both physics and cosmology. From the observational point of view, it is crucial to have various methods to assess cosmic expansion history, which can be alternative to standard candles (SNIa in cosmological context). Strongly gravitationally lensed systems create such a new opportunity by combining stellar kinematics with lensing geometry. Using strong gravitational lenses as probes of cosmic expansion is becoming attractive in light of ongoing surveys like SLACS based on different protocols than older searches focused on potential sources. In this approach, pursued recently by the authors, strongly lensed systems with known central velocity dispersions act as “standard rulers” — Einstein radius being standardized by stellar kinematics

HETERARCHICAL COORDINATION IN INTER-ORGANIZATIONAL NETWORKS: EVIDENCE FROM THE TOURISM INDUSTRY

Purpose – The aim of this paper is to report the results of a qualitative research on heterarchical coordination within an interorganizational network in the tourism sector. Design/Methodology/Approach – The study follows the qualitative approach and case study research design. The main data collection techniques were semi-structured interviews and document analysis. Data triangulation was used to collect and analyze qualitative research data and narrative form supported the presentation of the results. Findings – The study has shown the nature, strengths and weaknesses of heterarchical coordination within the distributed inter-firm network. Based on the study, heterarchy is an appropriate form of coordination for distributed inter-firm networks with a high proportion of SMEs operating in the tourism sector. Heterarchy supports a high level of engagement of focal firms in joint activities and emergent growth of the whole community. Originality of the research – The study brings a new overview of coordination mechanisms in inter-firm networks and identifies the characteristics and conditions of heterarchical coordination in a distributed cooperative network. The results of the study are useful for scholars studying business networks as well as for managers and local authorities responsible for managing and supporting inter-firm networks in tourism destinations

Effect of DGAT1 gene mutation in sows of dam-line on the composition of the produced milk and piglet rearing during 21-day lactation

Diacylglycerol acyltransferase 1 gene (DGAT1) involved in the synthesis and transport of triglycerides is located on chromosome 4 in pigs, in the region with about 200 QTLs responsible among other things for: fat thickness, daily gains, fat content and composition of fatty acids. It is thus probable that the gene polymorphism (as in cows) may affect the fat content in colostrum and milk of sows. The objective of the experiment was to assess the effect of DGAT1 polymorphism on the milk composition of sows and as a result on piglet rearing during the suckling period. The experiment was performed on 207 sows of breeds used in breeding program as a dam-line: polish large white (PLW) and polish landrace (PL). Colostrum and milk of sows were collected at 1, 7, 14 and 21 days of lactation to assay solids, total protein, fat and lactose. Data on piglet rearing performance were collected at 1, 7, 14 and 21 days of lactation. The tests performed showed that A/G rs45434075 DGAT1 mutation occurring in PLW and PL sows did not  significantly affect the quality of their colostrum and milk expressed as solids content, and at the same time on piglet rearing performance. However, it was observed that PLW sows of the DGAT1GG genotype was characterised by a higher fat content in colostrum, whereas PL sows of the same genotype had an increased protein content and a reduced lactose content in milk. Key words: DGAT1, Polymorphism, milk, rearing of piglets, maternal breed.Abbreviation:  PLW, Polish large white; PL, polish landrac

Distance Duality in Different Cosmological Models

At cosmological scales, one can actually measure two types of distances: luminosity distance dL and angular diameter distance dA. Within General Relativity, providing there are no processes eliminating photons from the beam, these two distances are related by the so-called distance duality relation. In this paper we used the measurements of the angular diameter distance of 38 cluster of galaxies by Bonamente et al. together with our own fits on the latest Union2 compilation of supernovae to test the distance duality relation in different cosmological models invoked to explain accelerating expansion of the Universe. Our results demonstrate that distance duality violation parameter (z) does not depend on the cosmological model assumed, but considerably depends on assumptions about mass density distribution profile of the cluster. Maximum likelihood estimates of might be interpreted as the distance duality violation. However, this effect is more pronounced for isothermal models of clusters than for the models based on hydrostatic equilibrium. This suggests that more sophisticated and accurate modeling of clusters mass density profiles is needed before the X-ray + SZ technique becomes competitive to other methods of measuring distances

Constraints on Cosmic Equation of State from Joint Analysis of Standard Rulers and Standard Candles

A key issue of contemporary cosmology is the problem of currently accelerating expansion of the Universe. The nature of this phenomenon is one of the most outstanding problems of physics and astronomy today. Its origin may be attributed to either unknown exotic material component with negative pressure — so-called Dark Energy (DE), to infra red modification of gravity at cosmological scale or requires to relax the assumption of homogeneity of the Universe. The strength of modern cosmology lies in consistency across independent pieces of evidence (like e.g. CMB anisotropies, the large-scale distribution of galaxies, the observed abundances of light elements, etc.) rather than in single one, crucial experiment. In this spirit we performed a joint analysis of two dark energy models using five different tests. These tests will be called diagnostics and include the data coming from supernovae, Gamma Ray Bursts, CMB acoustic peaks, Baryon Acoustic Oscillations and strong lensing systems. Part of the diagnostics makes use of the angular diameter distance, and part of them uses the luminosity distance splitting these probes into two categories: Standard Rules and Standard Candles. It was shown that combined analysis of them had higher restrictive power in the parameter space. The best fits we obtained for the model parameters in joint analysis turned out to prefer cases effectively equivalent to CDM model. Our findings are in agreement with paralel studies performed by other authors on different sets of diagnostic probes

On the Complementarity of Different Cosmological Probes with SLACS, BELLS and SL2S Strong Gravitational Lensing Data

Accelerating expansion of the Universe is now an indisputable observational fact and became one of the most important issues of both physics and cosmology today, known as dark energy (DE) problem. The nature of this phenomenon is still unknown and from observational point of view the only way to put some light on cosmic expansion history is to combine different methods which are alternative to each other. In this light, we explore the idea that strong gravitational lensing systems offer new opportunity to constrain DE parameters in a way complementary to other cosmological probes. It turns out that the angle of the confidence contour major axis for strong lensing measurements depends on the redshift of the sample what may help to break the degeneracy in the w0–wa parameters plane in the Chevalier–Polarski–Linder parametrization of DE equation of state