INTEGRAL high energy monitoring of the X-ray burster KS 1741-293

KS 1741-293, discovered in 1989 by the X-ray camera TTM in the Kvant module of the Mir space station and identified as an X-ray burster, has not been detected in the hard X band until the advent of the INTEGRAL observatory. Moreover this source has been recently object of scientific discussion, being also associated to a nearby extended radio source that in principle could be the supernova remnant produced by the accretion induced collapse in the binary system. Our long term monitoring with INTEGRAL, covering the period from February 2003 to May 2005, confirms that KS 1741-293 is transient in soft and hard X band. When the source is active, from a simultaneous JEM-X and IBIS data analysis, we provide a wide band spectrum from 5 to 100 keV, that can be fit by a two component model, a multiple blackbody for the soft emission and a Comptonized or a cut-off power law model for the hard component. Finally, by the detection of two X-ray bursters with JEM-X, we confirm the bursting nature of KS 1741-293, including this source in the class of the hard tailed X-ray bursters.Comment: 7 pages, accepted for publication on MNRA

Boundary conditions in the Unruh problem

We have analyzed the Unruh problem in the frame of quantum field theory and have shown that the Unruh quantization scheme is valid in the double Rindler wedge rather than in Minkowski spacetime. The double Rindler wedge is composed of two disjoint regions ($R$- and $L$-wedges of Minkowski spacetime) which are causally separated from each other. Moreover the Unruh construction implies existence of boundary condition at the common edge of $R$- and $L$-wedges in Minkowski spacetime. Such boundary condition may be interpreted as a topological obstacle which gives rise to a superselection rule prohibiting any correlations between $r$- and $l$- Unruh particles. Thus the part of the field from the $L$-wedge in no way can influence a Rindler observer living in the $R$-wedge and therefore elimination of the invisible "left" degrees of freedom will take no effect for him. Hence averaging over states of the field in one wedge can not lead to thermalization of the state in the other. This result is proved both in the standard and algebraic formulations of quantum field theory and we conclude that principles of quantum field theory does not give any grounds for existence of the "Unruh effect".Comment: 31 pages,1 figur

Identification of Clinically Relevant Protein Targets in Prostate Cancer with 2D-DIGE Coupled Mass Spectrometry and Systems Biology Network Platform

Prostate cancer (PCa) is the most common type of cancer found in men and among the leading causes of cancer death in the western world. In the present study, we compared the individual protein expression patterns from histologically characterized PCa and the surrounding benign tissue obtained by manual micro dissection using highly sensitive two-dimensional differential gel electrophoresis (2D-DIGE) coupled with mass spectrometry. Proteomic data revealed 118 protein spots to be differentially expressed in cancer (n = 24) compared to benign (n = 21) prostate tissue. These spots were analysed by MALDI-TOF-MS/MS and 79 different proteins were identified. Using principal component analysis we could clearly separate tumor and normal tissue and two distinct tumor groups based on the protein expression pattern. By using a systems biology approach, we could map many of these proteins both into major pathways involved in PCa progression as well as into a group of potential diagnostic and/or prognostic markers. Due to complexity of the highly interconnected shortest pathway network, the functional sub networks revealed some of the potential candidate biomarker proteins for further validation. By using a systems biology approach, our study revealed novel proteins and molecular networks with altered expression in PCa. Further functional validation of individual proteins is ongoing and might provide new insights in PCa progression potentially leading to the design of novel diagnostic and therapeutic strategies

The Effects of joint ENSO Antarctic Oscillation Forcing on the McMurdo Dry Valleys, Antarctica

Stable oxygen analyses and snow accumulation rates from snow pits sampled in the McMurdo Dry Valleys have been used to reconstruct variations in summer temperature and moisture availability over the last four decades. The temperature data show a common interannual variability, with strong regional warmings occurring especially in 1984/85, 1995/96 and 1990/91 and profound coolings during 1977/78, 1983/84, 1988/89, 1993/94, and 1996/97. Annual snow accumulation shows a larger variance between sites, but the early 1970s, 1984, 1997, and to a lesser degree 1990/91 are characterized overall by wetter conditions, while the early and late 1980s show low snow accumulation values. Comparison of the reconstructed and measured summer temperatures with the Southern Oscillation Index (SOI) and the Antarctic Oscillation (AAO) yield statistically significant correlations, which improve when phaserelationships are considered. A distinct change in the phase relationship of the correlation is observed, with the SOI-AAO leading over the temperature records by one year before, and lagging by one year after 1988. These results suggest that over the last two decades summer temperatures are influenced by opposing El Niho Southern Oscillation and AAO forcings and support previous studies that identified a change in the Tropical-Antarctic teleconnection between the 1980s and 1990s

Climate Drivers in the McMurdo Sound Region, Antarctica, over the last Millennium

On interannual to decadal time scales tropospheric Antarctic circulation is driven by three forces: ENSO (El Niño Southern Oscillation), AAO (Antarctic Oscillation or Southern Annular Mode), and potentially ACW (Antarctic Circumpolar Wave) but there is widespread disagreement on their relative influences and temporal robustness.We present high resolution records from three snow pits from the McMurdo Sound region (Victoria Lower Glacier, Evans Piedmont Glacier and Mt Erebus). The snow pits are dated using annual layer counting and represent up to ~50 years. Water chemistry (major ion Ca, K, Mg, Na & Cl, NO3, SO4, trace elements Al, Fe, Mn, P, S, Si, Sr), isotopic ratios (oxygen, deuterium, and d-excess data), dust concentration, and density fluctuations are presented. The ice core proxies were calibrated to meteorological (AWS) data using transfer functions.Our data support the concept of a double-sided ENSO effect in the Ross Sea Region, but show that the ENSO forcing is non-linear and non-stationary. We suggest a new mechanism that could explain a teleconnection with positive feedbacks between ENSO and AAO. Furthermore, we present data from a firn core from Victoria Lower Glacier representing the last millennium. The core has been dated using volcanic benchmarks found in the non-seasalt SO4 signal. The isotope record indicates a reoccurring pattern of rapid changes between cooler and warmer climate modes, suggesting that the relative influence of ENSO and AAO and possibly ACW has varied through time