Dark side of the universe in the Stephani cosmology

We investigate the late time acceleration of the universe in the context of the Stephani model. This solution generalizes those of Friedmann-Lemaitre-Robertson-Walker (FLRW) in such a way that the spatial curvature is a function of of time. We show that the inhomogeneity of the models can lead to an accelerated evolution of the universe that is analogous to that obtained with FLRW models through a cosmological constant or any exotic component for matter.Comment: 8 pages, 2 figure, many improvements; to appear in European Physical Journal

The effects of air permeability, background ventilation and lifestyle on energy performance, indoor air quality and risk of condensation in domestic buildings

Effective and efficient ventilation is essential when improving energy performance and Indoor Air Quality (IAQ) of buildings. Reducing air permeability can considerably improve the energy performance of buildings; however, making the buildings more airtight may result in lower rates of natural ventilation which may in turn increase the risks of condensation and unacceptable IAQ. This study evaluates the effects of different air permeability rates, background ventilation and occupants’ lifestyles on the energy performance as well as the risk of condensation and CO2 concentration in domestic buildings. Dynamic computer simulations were conducted in EnergyPlus. Results indicated direct relations between the ventilation rates, energy performance and IAQ. Higher air permeability along with background ventilation resulted in considerably better IAQ while energy consumption increased by up to four times. Occupants’ lifestyles were identified as a major contributor to the risk of condensation.This is the final version. It was first published by MDPI at http://www.mdpi.com/2071-1050/7/4/4022

A dynamical law for slow crack growth in polycarbonate films

We study experimentally the slow growth of a single crack in polycarbonate films submitted to uniaxial and constant imposed stress. For this visco-plastic material, we uncover a dynamical law that describes the dependence of the instantaneous crack velocity with experimental parameters. The law involves a Dugdale-Barenblatt static description of crack tip plastic zones associated to an Eyring's law and an empirical dependence with the crack length that may come from a residual elastic field

First report of Quaternary mammals from the Qalehjough area, Lut Desert, Eastern Iran

Taxonomic study of Quaternary mammal remains from the Qalehjough fossil site, eastern Iran, has resulted in the identification of two mammal orders, Artiodactyla and Perissodactyla, with four families and six taxa. Of particular note was the recovery of Stephanorhinus and a caballoid horse. These remains have provided the first opportunity to examine Late Quaternary faunal assemblages in the northern parts of the Lut Desert, eastern Iran. The Qalehjough faunal assemblage documents some zoogeographic characteristics of the eastern Iranian Plateau, and suggests that palaeoenvironments in this part of Iran during the Pleistocene were more humid and wooded than today. The disappearance of rhinoceroses and caballoid horses from this region is most likely a result of climate change and concomitant habitat loss

Comparison the self-concept and behavior in adolescents without criminal record with juvenile offenders

Background and aims: impermanent and negative self-concept , disrupts personal and social adjustment. in this study compared self-concept and behavior in adolescents without a history of juvenile criminal and offenders. Methods: The study was cross-sectional . 79 person from centers for Upbringing and correction via census sample and 120 person that with first group in regard to age-and sex- matched controls from Isfahan City were enrolled. The data collection instrument consisted of three sections include demographic information , self-concept and behavior questions. Statistic examination include T-test, Fisher and K2, were use for data analyzed . Results: The mean and standard deviation of self-Concept in offenders was 58/94±10/30 and Behavior was 62/26±28/81. Adolescents with no history of criminal record, self-concept score was 63/02±9/75 and Behavior was 84/66±15/22. Self-concept and behavior scores were significantly higher in the group with no criminal record (p<0/001). Conclusion: The results suggest that the Self-concept and Behavior of juvenile offenders is lower than adolescents with no criminal record. It is also considered demographic factors will affect the incidence of antisocial behavior . It seems psychologists and counselors to be working in these centers must training , counseling and therapy and correction techniques with consideration to the establishment of such anomalies

Quantum-limited estimation of the axial separation of two incoherent point sources

Improving axial resolution is crucial for three-dimensional optical imaging systems. Here we present a scheme of axial superresolution for two incoherent point sources based on spatial mode demultiplexing. A radial mode sorter is used to losslessly decompose the optical fields into a radial mode basis set to extract the phase information associated with the axial positions of the point sources. We show theoretically and experimentally that, in the limit of a zero axial separation, our scheme allows for reaching the quantum Cram\'er-Rao lower bound and thus can be considered as one of the optimal measurement methods. Unlike other superresolution schemes, this scheme does not require neither activation of fluorophores nor sophisticated stabilization control. Moreover, it is applicable to the localization of a single point source in the axial direction. Our demonstration can be useful to a variety of applications such as far-field fluorescence microscopy.Comment: Comments are welcom

Deterministically Computing Reduction Numbers of Polynomial Ideals

We discuss the problem of determining reduction number of a polynomial ideal I in n variables. We present two algorithms based on parametric computations. The first one determines the absolute reduction number of I and requires computation in a polynomial ring with (n-dim(I))dim(I) parameters and n-dim(I) variables. The second one computes via a Grobner system the set of all reduction numbers of the ideal I and thus in particular also its big reduction number. However,it requires computations in a ring with n.dim(I) parameters and n variables.Comment: This new version replaces the earlier version arXiv:1404.1721 and it has been accepted for publication in the proceedings of CASC 2014, Warsaw, Polna

Right-Handed Sector Leptogenesis

Instead of creating the observed baryon asymmetry of the universe by the decay of right-handed (RH) neutrinos to left-handed leptons, we propose to generate it dominantly by the decay of the RH neutrinos to RH leptons. This mechanism turns out to be successful in large regions of parameter space. It may work, in particular, at a scale as low as $\sim$~TeV, with no need to invoke quasi-degenerate RH neutrino masses to resonantly enhance the asymmetry. Such a possibility can be probed experimentally by the observation at colliders of a singlet charged Higgs particle and of RH neutrinos. Other mechanisms which may lead to successful leptogenesis from the RH lepton sector interactions are also briefly presented. The incorporation of these scenarios in left-right symmetric and unified models is discussed.Comment: 14 pages, latex, axodraw; minor clarifications and references added, extended discussion of the signatures at collider