Marek Biesiada

Urinary mercury and biomarkers of early renal dysfunction in environmentally and occupationally exposed adults: a three-country study.

We conducted a cross-sectional study in Sweden, Italy and Poland to assess environmental and occupational exposure to mercury from chloralkali (CA) plants and the potential association with biomarkers of early renal dysfunction. Questionnaire data and first-morning urine samples were collected from 757 eligible subjects. Urine samples were analysed for mercury corrected for creatinine (U-HgC), alpha-1-microglobulin (A1M), N-acetyl-beta-glucosaminidase (NAG) and albumin. Determinants of urinary mercury excretion were examined. Levels of kidney markers were compared in three U-HgC categories, and differences were tested taking age and other covariates into account. In the general population, the median U-HgC was higher in Italian (1.2 microg/gC) than in Polish (0.22 microg/gC) or Swedish (0.21 microg/gC) subjects, and no effect of living close to CA plants could be shown. Dental amalgam, chewing on amalgam, and fish consumption were positively associated with U-HgC. In subjects from the general population, no effects on the kidney markers could be detected, while in men, including workers occupationally exposed to mercury, U-HgC was positively associated with the kidney markers, especially with NAG, but to some extent also with A1M and albumin. Differences in urinary mercury and kidney markers in the general population between three studied countries could possibly be due to dietary factors, increased susceptibility to mercury at low selenium intake or co-exposure to other nephrotoxic metals.

Lorentz invariance violation-induced time delays in GRBs in different cosmological models

Lorentz invariance violation (LIV) manifesting itself by energy-dependent modification of standard relativistic dispersion relation has recently attracted a considerable attention. Ellis et al previously investigated the energy-dependent time offsets in different energy bands on a sample of gamma ray bursts and, assuming standard cosmological model, they found a weak indication for redshift dependence of time delays suggestive of LIV. Going beyond the ΛCDM cosmology we extend this analysis considering also four alternative models of dark energy (quintessence with constant and variable equation of state, Chaplygin gas and braneworld cosmology). It turns out that the effect noted by Ellis et al is also present in those models and is the strongest for quintessence with a variable equation of state.

Dark energy constraints from joint analysis of standard rulers and standard candles

We performed joint analysis of five cosmological models invoked to explain the accelerating expansion of the Universe. We used the data from strong gravitational lensing systems, locations of cosmic microwave background acoustic peaks and baryon acoustic oscillation data in combination with supernova Ia data (Union2 compilation). The observables we used came from both standard rulers and standard candles, so they had different parameter degeneracies and different restrictive powers in the parameter spaces of cosmological models. The best fits we obtained for the model parameters in joint analysis turned out to prefer cases effectively equivalent to the ΛCDM model. They were also in agreement with other combined studies performed by other authors on different sets of diagnostic probes. Information theoretic methods used to assess which model is most supported by the data lead to the conclusion that the concordance model ΛCDM is clearly preferred in joint analysis. The quintessence (both having constant or time varying equation of state) and Chaplygin gas get considerably less support from the data while the brane world (DGP) scenario is practically ruled out.

Strong gravitational lensing of gravitational waves in Einstein Telescope

Gravitational wave experiments have entered a new stage which gets us closer to the opening a new observational window on the Universe. In particular, the Einstein Telescope (ET) is designed to have a fantastic sensitivity that will provide with tens or hundreds of thousand NS-NS inspiral events per year up to the redshift z = 2. Some of such events should be gravitationally lensed by intervening galaxies. We explore the prospects of observing gravitationally lensed inspiral NS-NS events in the Einstein telescope. Being conservative we consider the lens population of elliptical galaxies. It turns out that depending on the local insipral rate ET should detect from one per decade detection in the pessimistic case to a tens of detections per year for the most optimistic case. The detection of gravitationally lensed source in gravitational wave detectors would be an invaluable source of information concerning cosmography, complementary to standard ones (like supernovae or BAO) independent of the local cosmic distance ladder calibrations.

Searching for invariant description of chaos in general relativity

The main objective of the paper is to propose invariant indicators of local instability in general relativity. The key idea is a very simple and old one: if one is able to formulate the dynamics as a geodesic flow then the sensitive dependence on initial conditions may be captured in terms of the Jacobi equation. Invariant indicators of local instability proposed in this paper are expressed by the invariant polynomials constructed out of the principal sectional curvatures. This procedure is applied to the Bianchi IX model in the high anisotropy approximation, which is a good asymptotic description near the singularity. It is demonstrated that trajectories are locally unstable there.

Gravitational lensing time delays as a tool for testing Lorentz-invariance violation

It is generally expected that quantum gravity theory should yield the model of a space–time foam at short distances leading to Lorentz-invariance violation (LIV) manifested e.g. by energy-dependent modification of the standard relativistic dispersion relation. One direction of research, pursued intensively, is to measure the energy-dependent time-of-arrival delays in photons emitted by astrophysical sources located at cosmological distances. This is tempered, however, by our ignorance of intrinsic emission delays in different energy channels. In this paper we discuss a test based on gravitational lensing. Monitoring time delays between images obtained in different energy channels, for example optical (low-energy) and TeV photons, may reveal extra delays due to the distorted dispersion relation typical in LIV theories, a test that is free from the systematics inherent in other settings.

What do parameterized Om(z) diagnostics tell us in light of recent observations

In this paper, we propose a new parametrization of

Primordial gravitational waves and multidimensional theories

Om(z)

Ultra-compact structure in radio quasars as a cosmological probe: a revised study of the interaction between cosmic dark sectors

diagnostics and show how the most recent and significantly improved observations concerning the

A new test of

H(z)