4,069 research outputs found
The BeppoSAX view of the hot cluster Abell 2319
We present results from a BeppoSAX observation of the rich cluster Abell
2319. The broad band spectrum (2-50 keV) of the cluster can be adequately
represented by an optically thin thermal emission model with a temperature of
9.6+/-0.3 keV and a metal abundance of 0.25+/-0.03 in solar units, and with no
evidence of a hard X-ray excess in the PDS spectrum. From the upper limit to
the hard tail component we derive a lower limit of ~0.04 \muG for the
volume-averaged intracluster magnetic field. By performing spatially resolved
spectroscopy in the medium energy band (2-10 keV), we find that the projected
radial temperature and metal abundance profiles are constant out to a radius of
16 arcmin (1.4 Mpc). A reduction of the temperature of 1/3, when going from the
cluster core out to 16 arcmin, can be excluded in the present data at the 99%
confidence level. From the analysis of the temperature and abundance maps we
find evidence of a temperature enhancement and of an abundance decrement in a
region localized 6 arcmin--8 arcmin NE of the core, where a merger event may be
taking place. Finally, the temperature map indicates that the subcluster
located NW of the main cluster may be somewhat cooler than the rest of the
cluster.Comment: To appear in ApJ-Letter
Seasonal and event-based hydrological and slope stability modeling of pyroclastic fall deposits covering slopes in Campania (Southern Italy)
The pyroclastic fall deposits mantling mountain slopes in the Campania region (Southern Italy) represent one of the most studied geomorphological frameworks of the world regarding rainfall-induced debris flows threating urban areas. The proposed study focused on advancing knowledge about the hydrological response of pyroclastic fall coverings from the seasonal to event-based time scales, leading to the initiation of slope instability. The study was based on two consequential tasks. The first was the analysis of a six-year monitoring of soil pressure head carried out in a sample area of the Sarno Mountains, located above a debris flow initiation zone. The second was based on coupled hydrological and slope stability modeling performed on the physical models of slopes, which were reconstructed by empirical correlations between the slope angle, total thickness, and stratigraphic settings of pyroclastic fall deposits mantling slopes. The results obtained were: (a) The understanding of a soil pressure head regime of the volcaniclastic soil mantle, always ranging in unsaturated conditions and characterized by a strong seasonal variability depending on precipitation patterns and the life cycle of deciduous chestnut forest; and (b) the reconstruction through a deterministic approach of seasonal intensity-duration rainfall thresholds related to different morphological conditions
Groundwater vulnerability of principal aquifers of the Campania region (southern Italy)
The assessment of groundwater vulnerability is an important aspect of territorial planning aimed at the management and protection of groundwater quality. This topic is particularly relevant for the Campania region (southern Italy) due to the abundance of groundwater resources and the strong dependence on them of current economic, social and environmental settings. The region is characterized by complex geological, structural and hydrogeological frameworks which make challenging and innovative the assessment of groundwater vulnerability with SINTACS, a parametric method officially recognized by the Italian environmental agencies. In order to apply results obtained to current regional regulations, groundwater vulnerability was estimated for the 80 principal aquifers, hosting respective groundwater bodies, as recognized by the application of the Directive 2000/60/EC. Among principal results, the alluvial and limestone (karst) aquifers, which are the most productive of the region, show the highest groundwater vulnerability, even with spatially variable conditions depending on local hydrogeological features
VLT/NACO adaptive optics imaging of the TY CrA system - A fourth stellar component candidate detected
We report the detection of a possible subsolar mass companion to the triple
young system TY CrA using the NACO instrument at the VLT UT4 during its
commissioning. Assuming for TY CrA a distance similar to that of the close
binary system HD 176386, the photometric spectral type of this fourth stellar
component candidate is consistent with an ~M4 star. We discuss the dynamical
stability of this possible quadruple system as well as the possible location of
dusty particles inside or outside the system.Comment: 4 pages, 2 figures postscrip
Different non-structural carbohydrates/crude proteins (NCS/CP) ratios in diet shape the gastrointestinal microbiota of water buffalo
The microbiota of the gastrointestinal tract (GIT) are crucial for host health and production efficiency in ruminants. Its microbial composition can be influenced by several endogenous and exogenous factors. In the beef and dairy industry, the possibility to manipulate gut microbiota by diet and management can have important health and economic implications. The aims of this study were to characterize the different GIT site microbiota in water buffalo and evaluate the influence of diet on GIT microbiota in this animal species. We characterized and compared the microbiota of the rumen, large intestine and feces of water buffaloes fed two different diets with different non-structural carbohydrates/crude proteins (NSC/CP) ratios. Our results indicated that Bacteroidetes, Firmicutes and Proteobacteria were the most abundant phyla in all the GIT sites, with significant differences in microbiota composition between body sites both within and between groups. This result was particularly evident in the large intestine, where beta diversity analysis displayed clear clustering of samples depending on the diet. Moreover, we found a difference in diet digestibility linked to microbiota modification at the GIT level conditioned by NSC/CP levels. Diet strongly influences GIT microbiota and can therefore modulate specific GIT microorganisms able to affect the health status and performance efficiency of adult animals
Protective Effect of Hydroxytyrosol Against Oxidative Stress Induced by the Ochratoxin in Kidney Cells: in vitro and in vivo Study
Ochratoxin-A (OTA) is a mycotoxin that is a common contaminant of food products for both humans and animals. This mycotoxin has several toxic effects. In particular, ochratoxin has significant nephrotoxic potential. In fact, OTA has been described as being responsible for naturally occurring animal and human kidney disorders. The toxicity of this mycotoxin involves the induction of the oxidative stress pathways. Therefore, in the present study, we wanted to evaluate the potential protective effects of hydroxytyrosol (HT), a phenolic constituent with potent antioxidant activity, of extra virgin olive oil in three different renal cell lines, the Madin-Darby canine kidney cell line (MDCK), a pig kidney cell line (LLC-PK1), and a rabbit kidney cell line (RK 13), and in rats. Our results clearly showed that renal cells respond to OTA exposure by reducing cell proliferation and the induction of oxidative stress. Pre-incubation of the cells with HT prevented the cellular cytotoxicity and increased reactive oxygen species (ROS) levels induced by OTA. In addition, the antioxidative activity of HT was studied by measuring malondialdehyde (MDA) and lactate dehydrogenase (LDH) levels and nitrosative stress. Finally, we investigated the capability of HT (20 mg/kg, intraperitoneally) to act in vivo. In rats, HT reduced oxidative stress and collagen accumulation in the kidney and counteracted the augmentations in AST, ALT, and creatinine levels following OTA induction (250 ÎŒg/kg for 90 days orally). In conclusion, our findings demonstrate that HT is able to protect three renal cell lines from the damage induced by OTA and protect the kidneys of rats. Therefore, the use of this compound could be an important strategy for the treatment and prevention of this type of kidney dysfunction
Probing the origin of the toxicity of oligomeric aggregates of α-synuclein with antibodies
Hard X-ray and radio observations of Abell 754
We present a long BeppoSAX observation of Abell 754 that reports a nonthermal
excess with respect to the thermal emission at energies greater than ~45 keV. A
VLA radio observation at 1.4 GHz definitely confirms the existence of diffuse
radio emission in the central region of the cluster, previously suggested by
images at 74 and 330 MHz (Kassim et al 2001), and reports additional features.
Besides, our observation determines a steeper radio halo spectrum in the
330-1400 MHz frequency range with respect to the spectrum detected at lower
frequencies, indicating the presence of a spectral cutoff. The presence of a
radio halo in A754, considered the prototype of a merging cluster, reinforces
the link between formation of Mpc-scale radio regions and very recent or
current merger processes. The radio results combined with the hard X-ray excess
detected by BeppoSAX give information on the origin of the electron population
responsible for nonthermal phenomena in galaxy clusters. We discuss also the
possibility that 26W20, a tailed radio galaxy with BL Lac characteristics
located in the field of view of the PDS, could be responsible for the observed
nonthermal hard X-ray emission.Comment: 7 pages, 3 figures; Astronomy & Astrophysics, in pres
Isolation of a SIR-like gene, SIR-T8, that is overexpressed in thyroid carcinoma cell lines and tissues
We used subtractive library screening to identify the changes that occur in gene expression during thyroid cell neoplastic transformation. Complementary DNA from normal thyroid cells (HTC 2) was subtracted from a complementary DNA library constructed from a human thyroid papillary carcinoma cell line. The library was screened for genes upregulated in human thyroid papillary carcinoma cell line cells, and several cDNA clones were isolated. One of these clones has a sirtuin core and high homology with the human silent information regulator protein family. This clone, designated âSIR-T8â, was overexpressed in human thyroid carcinoma cell lines and tissues, but not in adenomas. The human SIR-T8 protein has a molecular weight of 39âkDa and is primarily located in the cytoplasm under the nuclear membrane. The SIR-T8 gene is located on chromosome 17q25-1
Physically based estimation of rainfall thresholds triggering shallow landslides in volcanic slopes of Southern Italy
On the 4th and 5th of March 2005, about 100 rainfall-induced landslides occurred along volcanic slopes of Camaldoli Hill in Naples, Italy. These started as soil slips in the upper substratum of incoherent and welded volcaniclastic deposits, then evolved downslope according to debris avalanche and debris flow mechanisms. This specific case of slope instability on complex volcaniclastic deposits remains poorly characterized and understood, although similar shallow landsliding phenomena have largely been studied in other peri-volcanic areas of the Campania region underlain by carbonate bedrock. Considering the landslide hazard in this urbanized area, this study focused on quantitatively advancing the understanding of the predisposing factors and hydrological conditions contributing to the initial landslide triggering. Borehole drilling, trial pits, dynamic penetrometer tests, topographic surveys, and infiltration tests were conducted on a slope sector of Camaldoli Hill to develop a geological framework model. Undisturbed soil samples were collected for laboratory testing to further characterize hydraulic and geotechnical properties of the soil units identified. In situ soil pressure head monitoring probes were also installed. A numerical model of two-dimensional variably saturated subsurface water flow was parameterized for the monitored hillslope using field and laboratory data. Based on the observed soil pressure head dynamics, the model was calibrated by adjusting the evapotranspiration parameters. This physically based hydrologic model was combined with an infinite-slope stability analysis to reconstruct the critical unsaturated/saturated conditions leading to slope failure. This coupled hydromechanical numerical model was then used to determine intensityâduration (I-D) thresholds for landslide initiation over a range of plausible rainfall intensities and topographic slope angles for the region. The proposed approach can be conceived as a practicable method for defining a warning criterion in urbanized areas threatened by rainfall-induced shallow landslides, given the unavailability of a consistent inventory of past landslide events that prevents a rigorous empirical analysis
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