Dark energy and dark matter from cosmological observations

The present status of our knowledge about the dark matter and dark energy is reviewed. Bounds on the content of cold and hot dark matter from cosmological observations are discussed in some detail. I also review current bounds on the physical properties of dark energy, mainly its equation of state and effective speed of sound.Comment: 12 pages, 4 figures, to appear in Lepton-Photon 2005 proceedings, added figure and typos correcte

Defined Folate-PEG-siRNA Conjugates for Receptor-specific Gene Silencing

Gene silencing mediated by small interfering RNA (siRNA) is a novel approach in the development of new cancer therapeutics. Polycations used for nucleic acid delivery still remain heterogeneous compounds, despite continuous progress in polymer synthetic technologies. Here we report the development of a structural defined folic acid polyethylene glycol (PEG) siRNA conjugate accessible via click chemistry yielding a monodisperse ligand-PEG-siRNA conjugate. The folic acid targeting ligand was synthesized by solid phase supported peptide chemistry. The conjugate was shown to be specifically internalized into folic acid receptor expressing cells. When combined with a structurally defined polycation, again synthesized with the precision of solid phase chemistry, efficient receptor specific gene silencing is achieved

Osteoprotegerin is a new regulator of inflammation and angiogenesis in proliferative diabetic retinopathy

Osteoprotegerin (OPG) is a novel regulator of endothelial cell function, angiogenesis, and vasculogenesis. We correlated expression levels of OPG with those of the angiogenic and inflammatory factors vascular endothelial growth factor (VEGF) and monocyte chemoattractant protein-1 (MCP-1/CCL2) in proliferative diabetic retinopathy (PDR). We also examined expression of OPG in retinas from diabetic rats and diabetic patients and measured production of OPG by human retinal microvascular endothelial cells (HRMEC) and investigated its angiogenic activity.status: publishe

Probing dark energy with the next generation X-ray surveys of galaxy clusters

We present forecasts on the capability of future wide-area high-sensitivity X-ray surveys of galaxy clusters to yield constraints on the parameters defining the Dark Energy (DE) equation of state (EoS). Our analysis is carried out for future X-ray surveys which have enough sensitivity to provide accurate measurements of X-ray mass proxies and Fe-line based redshifts for about 2x10^4 clusters. We base our analysis on the Fisher Matrix formalism, by combining information on the cluster number counts and power spectrum, also including, for the first time in the analysis of the large scale cluster distribution, the effect of linear redshift-space distortions (RSDs). This study is performed with the main purpose of dissecting the cosmological information provided by geometrical and growth tests, which are both included in the analysis of number counts and clustering of galaxy clusters. We compare cosmological constraints obtained by assuming different levels of prior knowledge of the parameters which define the observable-mass X-ray relation. This comparison further demonstrates the fundamental importance of having a well calibrated observable-mass relation and, most importantly, its redshift evolution. Such a calibration can be achieved only by having at least $\sim 10^3$ net photon counts for each cluster included in the survey. We show that RSDs in the power spectrum analysis carry important cosmological information also when traced with galaxy clusters and the DE FoM increases by a factor of 8. Besides confirming the potential that large cluster surveys have in constraining the nature of DE, our analysis emphasizes that a full exploitation of the cosmological information carried by such surveys requires not only a large statistic but also a robust measurement of the mass proxies and redshifts for a significant fraction of the cluster sample, derived from the same X-ray survey data.Comment: 16 pages, 14 figures,published on MNRA

Remnant radio-loud AGN in the Herschel-ATLAS field

Only a small fraction of observed active galactic nuclei (AGN) display large-scale radio emission associated with jets, yet these radio-loud AGN have become increasingly important in models of galaxy evolution. In determining the dynamics and energetics of the radio sources over cosmic time, a key question concerns what happens when their jets switch off. The resulting ‘remnant' radio-loud AGN have been surprisingly evasive in past radio surveys, and therefore statistical information on the population of radio-loud AGN in their dying phase is limited. In this paper, with the recent developments of Low-Frequency Array (LOFAR) and the Very Large Array, we are able to provide a systematically selected sample of remnant radio-loud AGN in the Herschel-ATLAS field. Using a simple core-detection method, we constrain the upper limit on the fraction of remnants in our radio-loud AGN sample to 9 per cent, implying that the extended lobe emission fades rapidly once the core/jets turn off. We also find that our remnant sample has a wide range of spectral indices (−1.5 ⩽ α1400150 ⩽ −0.5), confirming that the lobes of some remnants may possess flat spectra at low frequencies just as active sources do. We suggest that, even with the unprecedented sensitivity of LOFAR, our sample may still only contain the youngest of the remnant population

How close can an Inhomogeneous Universe mimic the Concordance Model?

Recently, spatially inhomogeneous cosmological models have been proposed as an alternative to the LCDM model, with the aim of reproducing the late time dynamics of the Universe without introducing a cosmological constant or dark energy. This paper investigates the possibility of distinguishing such models from the standard LCDM using background or large scale structure data. It also illustrates and emphasizes the necessity of testing the Copernican principle in order to confront the tests of general relativity with the large scale structure.Comment: 15 pages, 7 figure

The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey::N-body Mock Challenge for the eBOSS Emission Line Galaxy Sample

21 pages, 7 figures and 9 tables, A summary of all SDSS BAO and RSD measurements with accompanying legacy figures can be found at https://www.sdss.org/science/final-bao-and-rsd-measurements/ . The full cosmological interpretation of these measurements can be found at https://www.sdss.org/science/cosmology-results-from-eboss/ . Comments are welcomeInternational audienceCosmological growth can be measured in the redshift space clustering of galaxies targeted by spectroscopic surveys. Accurate prediction of clustering of galaxies will require understanding galaxy physics which is a very hard and highly non-linear problem. Approximate models of redshift space distortion (RSD) take a perturbative approach to solve the evolution of dark matter and galaxies in the universe. In this paper we focus on eBOSS emission line galaxies (ELGs) which live in intermediate mass haloes. We create a series of mock catalogues using haloes from the Multidark and {\sc Outer Rim} dark matter only N-body simulations. Our mock catalogues include various effects inspired by baryonic physics such as assembly bias and the characteristics of satellite galaxies kinematics, dynamics and statistics deviating from dark matter particles. We analyse these mocks using the TNS RSD model in Fourier space and the CLPT in configuration space. We conclude that these two RSD models provide an unbiased measurement of redshift space distortion within the statistical error of our mocks. We obtain the conservative theoretical systematic uncertainty of $3.3\%$, $1.8\%$ and $1.5\%$ in $f\sigma_8$, $\alpha_{\parallel}$ and $\alpha_{\bot}$ respectively for the TNS and CLPT models. We note that the estimated theoretical systematic error is an order of magnitude smaller than the statistical error of the eBOSS ELG sample and hence are negligible for the purpose of the current eBOSS ELG analysis

A cosmic speed-trap: a gravity-independent test of cosmic acceleration using baryon acoustic oscillations

We propose a new and highly model-independent test of cosmic acceleration by comparing observations of the baryon acoustic oscillation (BAO) scale at low and intermediate redshifts: we derive a new inequality relating BAO observables at two distinct redshifts, which must be satisfied for any reasonable homogeneous non-accelerating model, but is violated by models similar to LambdaCDM, due to acceleration in the recent past. This test is fully independent of the theory of gravity (GR or otherwise), the Friedmann equations, CMB and supernova observations: the test assumes only the Cosmological Principle, and that the length-scale of the BAO feature is fixed in comoving coordinates. Given realistic medium-term observations from BOSS, this test is expected to exclude all homogeneous non-accelerating models at ~ 4\sigma significance, and can reach ~ 7\sigma with next-generation surveys.Comment: Latex, 10 pages, 2 figures. Updated to match published versio

Antidiabetic and Antioxidant Effect of Scoparia dulcis in Alloxan induced Albino Mice

Abstract: Herbal drugs are frequently considered to be less toxic and also free from side effects, than synthetic ones. Hence, the present study was designed to evaluate antidiabetic and antioxidant principle of the ethanolic extract of Scoparia dulcis (EESD) for its antidiabetic and antioxidant potential against alloxan-induced diabetic mice. Hypoglycemic effect was evaluated in normal and alloxan induced diabetic mice The oral administration of plant extract at a dose of 100 & 200 mg/kg body weight were given to fasting glucose loaded (200 mg/kg body weight) mice with regard to normal control during 3 hr. study period and in alloxan-induced (150 mg/kg body weight) diabetic mice in comparison with reference drug, Metformin (600µg/kg) during 2 weeks study period. Considerable fall in elevated blood glucose level was observed in the normoglycemic (p<0.05) and alloxan induced diabetic (p<0.001) mice. The extract, at a dose of 100 & 200 mg/kg body weight showed glucose level reduction of 31.87% & 46.97% respectively in alloxaninduced diabetic mice while 50.74% was found for Metformin after 2 weeks. The antioxidant potential of ethanolic extract of plant was assessed by DPPH (1, 1-Diphenyl, 2-picryl-hydrazyl) free radical scavenging assay at 517 nm and total antioxidant capacity by phosphomolybdenum method at 695 nm.The extract showed petite free radical scavenging capacity (IC 50 value 243.82 μg/ml for plant extract and 58.92 μg/ml for Ascorbic acid) and moderate total antioxidant capacity compared with Ascorbic acid. These results demonstrate the antidiabetic and antioxidant potential of ethanolic extracts of Scoparia dulcis and suggests that the plant may have therapeutic value in diabetes and related complications

Signatures of Thermal Dilepton Radiation at RHIC

The properties of thermal dilepton production from heavy-ion collisions in the RHIC energy regime are evaluated for invariant masses ranging from 0.5 to 3 GeV. Using an expanding thermal fireball to model the evolution through both quark-gluon and hadronic phases various features of the spectra are addressed. In the low-mass region, due to an expected large background, the focus is on possible medium modifications of the narrow resonance structures from $\omega$ and $\phi$ mesons, whereas in the intermediate-mass region the old idea of identifying QGP radiation is reiterated including effects of chemical under-saturation in the early stages of central Au+Au collisions.Comment: 17 pages ReVTeX including 16 figure