Halo White Dwarfs and the Hot Intergalactic Medium

We present a schematic model for the formation of baryonic galactic halos and hot gas in the Local Group and the intergalactic medium. We follow the dynamics, chemical evolution, heat flow and gas flows of a hierarchy of scales, including: protogalactic clouds, galactic halos, and the Local Group itself. Within this hierarchy, the Galaxy is built via mergers of protogalactic fragments. We find that early bursts of star formation lead to a large population of remnants (mostly white dwarfs), which would reside presently in the halo and contribute to the dark component observed in the microlensing experiments. The hot, metal-rich gas from early starbursts and merging evaporates from the clouds and is eventually incorporated into the intergalactic medium. The model thus suggests that most microlensing objects could be white dwarfs (m \sim 0.5 \msol), which comprise a significant fraction of the halo mass. Furthermore, the Local Group could have a component of metal-rich hot gas similar to, although less than, that observed in larger clusters. We discuss the known constraints on such a scenario and show that all local observations can be satisfied with present data in this model. The best-fit model has a halo that is 40% baryonic, with an upper limit of 77%.Comment: 15 pages, LaTex, uses aas2pp4.sty, 7 postscript figures. Substantially revised and enlarged to a full-length article. Somewhat different quantitative results, but qualitative conclusions unchange

Spectral states evolution of 4U 1728-34 observed by INTEGRAL and RXTE: non-thermal component detection

We report results of a one-year monitoring of the low mass X-ray binary (LMXB) source (atoll type) 4U 1728-34 with INTEGRAL and RXTE. Three time intervals were covered by INTEGRAL, during which the source showed strong spectral evolution. We studied the broad-band X-ray spectra in detail by fitting several models in the different sections of the hardness-intensity diagram. The soft states are characterised by prominent blackbody emission plus a contribution from a Comptonized emission. The hard states are characterised by the presence of an excess flux with respect to the Comptonization model above 50 keV while the soft component is fainter. To obtain an acceptable fit to the data this excess is modeled either with a power law with photon index Gamma ~ 2 or a Comptonization (CompPS) spectrum implying the presence of hybrid thermal and non-thermal electrons in a corona. This makes 4U 1728-34 one of the few LMXBs of atoll type showing non-thermal emission at high energy. From our analysis, it is also apparent that the presence of the hard tail is more prominent as the overall spectrum becames harder. We discuss also alternative models which can discribe these hard states.Comment: Accepted for publication in MNRAS (accepted 2011 April 20. Received 2011 April 20; in original form 2010 December 07); 9 pages, 7 figure

A new strategy to prevent biofilm and clot formation in medical devices: the use of atmospheric non-thermal plasma assisted deposition of silver-based nanostructured coatings

In industrialized countries, health care associated infections, the fourth leading cause of dis- ease, are a major health issue. At least half of all cases of nosocomial infections are associ- ated with medical devices. Antibacterial coatings arise as an important approach to restrict the nosocomial infection rate without side effects and the development of antibiotic resis- tance. Beside nosocomial infections, clot formation affects cardiovascular medical devices and central venous catheters implants. In order to reduce and prevent such infection, we develop a plasma-assisted process for the deposition of nanostructured functional coatings on flat substrates and mini catheters. Silver nanoparticles (Ag NPs) are synthesized exploit- ing in-flight plasma-droplet reactions and are embedded in an organic coating deposited through hexamethyldisiloxane (HMDSO) plasma assisted polymerization. Coating stability upon liquid immersion and ethylene oxide (EtO) sterilization is assessed through chemical and morphological analysis carried out by means of Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). In the perspective of future clinical appli- cation, an in vitro analysis of anti-biofilm effect has been done. Moreover, we employed a murine model of catheter-associated infection which further highlighted the performance of Ag nanostructured films in counteract biofilm formation. The anti-clot performances coupled by haemo- and cytocompatibility assays have also been performed

Landuse and soil degradation in the southern Maya lowlands, from Pre-Classic to Post-Classic times : The case of La Joyanca (Petén, Guatemala)

International audienceThis work focuses on the impact of Maya agriculture on soil degradation. In site and out site studies in the area of the city of La Joyanca (NW Petén) show that "Maya clays" do not constitute a homogeneous unit, but represent a complex sedimentary record. A high resolution analysis leads us to document changes in rates and practices evolving in time in relation with major socio-political and economic changes. It is possible to highlight extensive agricultural practices between Early Pre-classical to Late Pre-classical times. Intensification occurs in relation with reduction of the fallow duration during Pre-classic to Classic periods. The consequences of these changes on soil erosion are discussed. However, it does not seem that the agronomic potential of the soils was significantly degraded before the end of the Classic period

Barcoding T Cell Calcium Response Diversity with Methods for Automated and Accurate Analysis of Cell Signals (MAAACS)

International audienceWe introduce a series of experimental procedures enabling sensitive calcium monitoring in T cell populations by confocal video-microscopy. Tracking and post-acquisition analysis was performed using Methods for Automated and Accurate Analysis of Cell Signals (MAAACS), a fully customized program that associates a high throughput tracking algorithm, an intuitive reconnection routine and a statistical platform to provide, at a glance, the calcium barcode of a population of individual T-cells. Combined with a sensitive calcium probe, this method allowed us to unravel the heterogeneity in shape and intensity of the calcium response in T cell populations and especially in naive T cells, which display intracellular calcium oscillations upon stimulation by antigen presenting cells

The IDENTIFY study: the investigation and detection of urological neoplasia in patients referred with suspected urinary tract cancer - a multicentre observational study

Objective To evaluate the contemporary prevalence of urinary tract cancer (bladder cancer, upper tract urothelial cancer [UTUC] and renal cancer) in patients referred to secondary care with haematuria, adjusted for established patient risk markers and geographical variation. Patients and Methods This was an international multicentre prospective observational study. We included patients aged ≥16 years, referred to secondary care with suspected urinary tract cancer. Patients with a known or previous urological malignancy were excluded. We estimated the prevalence of bladder cancer, UTUC, renal cancer and prostate cancer; stratified by age, type of haematuria, sex, and smoking. We used a multivariable mixed-effects logistic regression to adjust cancer prevalence for age, type of haematuria, sex, smoking, hospitals, and countries. Results Of the 11 059 patients assessed for eligibility, 10 896 were included from 110 hospitals across 26 countries. The overall adjusted cancer prevalence (n = 2257) was 28.2% (95% confidence interval [CI] 22.3–34.1), bladder cancer (n = 1951) 24.7% (95% CI 19.1–30.2), UTUC (n = 128) 1.14% (95% CI 0.77–1.52), renal cancer (n = 107) 1.05% (95% CI 0.80–1.29), and prostate cancer (n = 124) 1.75% (95% CI 1.32–2.18). The odds ratios for patient risk markers in the model for all cancers were: age 1.04 (95% CI 1.03–1.05; P < 0.001), visible haematuria 3.47 (95% CI 2.90–4.15; P < 0.001), male sex 1.30 (95% CI 1.14–1.50; P < 0.001), and smoking 2.70 (95% CI 2.30–3.18; P < 0.001). Conclusions A better understanding of cancer prevalence across an international population is required to inform clinical guidelines. We are the first to report urinary tract cancer prevalence across an international population in patients referred to secondary care, adjusted for patient risk markers and geographical variation. Bladder cancer was the most prevalent disease. Visible haematuria was the strongest predictor for urinary tract cancer