2,300 research outputs found
Adaptive constraints for feature tracking
In this paper extensions to an existing tracking algorithm are described.
These extensions implement adaptive tracking constraints in the form
of regional upper-bound displacements and an adaptive track smoothness
constraint. Together, these constraints make the tracking algorithm
more flexible than the original algorithm (which used fixed tracking
parameters) and provide greater confidence in the tracking results.
The result of applying the new algorithm to high-resolution ECMWF
reanalysis data is shown as an example of its effectiveness
Detecting Compton Reflection and a Broad Iron Line in MCG-5-23-16 with the Rossi X-ray Timing Explorer
We report the detection with the Rossi X-ray Timing Explorer of a Compton
reflection signature in the Seyfert galaxy MCG-5-23-16. RXTE also resolves the
Fe K-alpha fluorescence line with FWHM ~48,000 km s^{-1}. This measurement
provides the first independent confirmation of ASCA detections in Seyfert
galaxies of broad Fe K-alpha lines that are thought to be the signature of
emission from the inner regions of an accretion disk orbiting a black hole.
Under the assumption that reflection arises from an isotropic source located
above a neutral accretion disk, and using a theoretical model that accounts for
the dependence of the reflected spectrum on inclination angle, we derive a 90%
confidence range for the disk inclination of i = 50 to 81 degrees. The large
inclination is consistent with that expected from the unified model for
MCG-5-23-16 based on its Seyfert 1.9 classification. If we assume that the
high-energy cutoff in the incident spectrum lies at energies larger than a few
hundred keV, then the equivalent width of the Fe K-alpha line is much larger
than predicted for the amount of reflection. This implies either an enhanced
iron abundance, a covering factor of reflecting material > 0.5, or a cutoff in
the incident spectrum at energies between ~60 and ~200 keV.Comment: Accepted for publication in ApJ, LaTeX. 14 pages including 3 figures,
with 1 table as a separate postscript file. Typo corrected in abstrac
Fish assemblages across the Mediterranean Sea and the effects of protection from fishing = I Popolamenti ittici nel Mediterraneo e gli effetti della protezione dall’impatto della pesca
Several studies have assessed the effectiveness of individual marine protected areas (MPAs) in protecting fish assemblages, but regional assessments of multiple parks are scarce. Here fish surveys using visual census were done in marine parks and fished areas at 31 locations across
the Mediterranean Sea. Fish species richness, diversity and biomass (especially of top predators) were higher in MPAs compared to fished areas, and community structure differed significantly between MPAs and fished areas. Results suggest that MPAs are generally effective means to protect and recover fish populations and assemblages
Physical Adsorption at the Nanoscale: Towards Controllable Scaling of the Substrate-Adsorbate van der Waals Interaction
The Lifshitz-Zaremba-Kohn (LZK) theory is commonly considered as the correct
large-distance limit for the van der Waals (vdW) interaction of adsorbates
(atoms, molecules, or nanoparticles) with solid substrates. In the standard
approximate form, implicitly based on "local" dielectric functions, the LZK
approach predicts universal power laws for vdW interactions depending only on
the dimensionality of the interacting objects. However, recent experimental
findings are challenging the universality of this theoretical approach at
finite distances of relevance for nanoscale assembly. Here, we present a
combined analytical and numerical many-body study demonstrating that physical
adsorption can be significantly enhanced at the nanoscale. Regardless of the
band gap or the nature of the adsorbate specie, we find deviations from
conventional LZK power laws that extend to separation distances of up to 10--20
nanometers. Comparison with recent experimental observation of ultra
long-ranged vdW interactions in the delamination of graphene from a silicon
substrate reveals qualitative agreement with the present theory. The
sensitivity of vdW interactions to the substrate response and to the adsorbate
characteristic excitation frequency also suggests that adsorption strength can
be effectively tuned in experiments, paving the way to an improved control of
physical adsorption at the nanoscale
Smoking as a cofactor for causation of chronic pancreatitis: a meta-analysis.
OBJECTIVES: To assess the evidence for tobacco smoking as a risk factor for the causation of chronic pancreatitis.
METHODS: We performed a meta-analysis with random-effects models to estimate pooled relative risks (RRs) of chronic pancreatitis for current, former, and ever smokers, in comparison to never smokers. We also performed dose-response, heterogeneity, publication bias, and sensitivity analyses.
RESULTS: Ten case-control studies and 2 cohort studies that evaluated, overall, 1705 patients with chronic pancreatitis satisfied the inclusion criteria. When contrasted to never smokers, the pooled risk estimates for current smokers was 2.8 (95% confidence interval [CI], 1.8-4.2) overall and 2.5 (95% CI, 1.3-4.6) when data were adjusted for alcohol consumption. A dose-response effect of tobacco use on the risk was ascertained: the RR for subjects smoking less than 1 pack per day was 2.4 (95% CI, 0.9-6.6) and increased to 3.3 (95% CI, 1.4-7.9) in those smoking 1 or more packs per day. The risk diminished significantly after smoking cessation, as the RR estimate for former smokers dropped to a value of 1.4 (95% CI, 1.1-1.9).
CONCLUSIONS: Tobacco smoking may enhance the risk of developing chronic pancreatitis. Recommendation for smoking cessation, besides alcohol abstinence, should be incorporated in the management of patients with chronic pancreatitis
Machine milking management and milk nitrogen fractions in primiparous ewes
Little work has been carried out on management techniques to reduce stress of first machine
milking in ewes. The aim of this work was to evaluate the effect of milking parlour training before weaning on sheep
milk yield and milk protein fractions. One week before weaning, an experimental group (EG) was introduced into
the machine milking parlour and hand-milked once a day, to adapt them to the new environment and noise of the
milking machine, while a control group (CG) was hand-milked once a day in a traditional fold parlour until weaning.
After weaning, both groups were machine milked, separately, twice a day in the milking parlour. Milk yield and
nitrogen fractions were recorded for the first 10 days of machine milking. Differences between samplings within
group were observed for all parameters considered. Only on the first day of machine milking, differences between
groups occurred for total nitrogen, total protein and casein. Higher content of nitrogen fractions in the milk of EG
was due to its lower milk production. In fact, daily production of nitrogen fractions was higher in CG than in EG.
High variability for most parameters was observed during the first 5 days of machine milking in both groups. A
week of training to machine milking parlour was not enough to reduce the negative effects of weaning and machine
milking stresses on primiparous ewes. (interaction?
Particle-vibration coupling in halo nuclei
In halo nuclei like 11 Li and 12 Be, polarization effects based on the particle-vibration coupling mechanism leads to a density dependent pairing interaction which provides most of the observed correlation energy which stabilizes the least two bound neutrons. The same mechanism is at the basis of the parity inversion phenomenon observed in 10 Li and 11 Be
Molecular Recognition of Metal Complexes by DNA: A Comparative Study of the Interactions of the Parent Complexes [PtCl(TERPY)]Cl and [AuCl(TERPY)]Cl (2) with Double Stranded DNA
The interactions of the parent complexes [AuCl(Terpy)]Cl2 and [PtCl(Terpy)]Cl with DNA were analysed
by various physicochemical methods. Surprisingly, these metal complexes produce different interaction
patterns with DNA in spite of their profound structural similarity. Indeed, important modifications are
detected in the characteristic UV-Vis bands of [PtCl(Terpy)]Cl upon addition of ct-DNA, while the spectrum
of [AuCl(Terpy)]Cl2 is almost unaffected. Gel electrophoresis studies confirm these findings:
[PtCl(Terpy)]Cl — but not [AuCl(Terpy)]Cl2 — retards significantly the mobility of the supercoiled form of the
pHV14 plasmid after a short incubation time. Ultrafiltration studies indicate that the affinity of
[PtCl(Terpy)]Cl for ct-DNA is significantly greater than that of [AuCl(Terpy)]Cl2. On the other hand, both
[AuCl(Terpy)]Cl2 and [PtCl(Terpy)]Cl induce important changes in the CD spectrum of ct-DNA, at high
concentration, and increase its Tm value. Remarkably, the analysed metal-complex/DNA interaction patterns
depend critically on the incubation times. We propose that [PtCl(Terpy)]Cl quickly intercalates DNA; then,
formation of coordinative bonds progressively takes place with time. At variance, [AuCl(Terpy)]Cl2 first
interacts electrostatically with the DNA surface, with subsequent slow formation of some coordinative bonds
LDOC-1 and PARP-1 mRNA expression in leukocytes of father and son with cutaneous malignant melanoma
Abstract
Apoptosis is central to the biology of cutaneous malignant melanoma (CMM). The leucine zipper, down regulated in cancer 1 (LDOC-1) gene, is known to be a regulator of the nuclear factor kappa B (NF-kB) through inhibition of the same NF-kB. The poly (ADP-ribose) polymerase-1 (PARP1) gene plays an important role for the efficient maintenance of genome integrity. PARP-1 protein is required for the apoptosis-inducing factor (AIF) translocation from the mitochondria to the nucleus. We report here two interesting cases of family melanoma, a father and son 84 and 40 years old, respectively. The histological evaluation of the lesions of both men revealed diffused superficial melanoma with epithelioid cells. We evaluated the differential expression of LDOC-1 and PARP-1 mRNA in peripheral blood leukocytes of both the father and son. We found that both LDOC-1 and PARP-1 genes were down-regulated in both patients compared with those of controls. These data suggest that low levels of expression of LDOC-1 and PARP-1 mRNA may be associated with familial melanoma
Characterization of power transistors as high dose dosimeters
A bipolar transistor, previously investigated as a possible radiation dosimeter and tested under industrial irradiation conditions in high-activity gamma and high-energy, high-power electron beam facilities has been subjected to stability test in order to understand its behaviour and help to improve its performances. Charge carrier lifetime was measured for several sets of transistors which were then irradiated with various doses (3-60 kGy): seven sets with Co-60 gamma rays and eight with a 10MeV electron beam. After irradiation all the transistors were measured and each set was divided into three groups: one group was left untreated, the second group was heated at 100 degrees C for 30 minutes and the third group was heated at 150 degrees C for 30 minutes, for testing the stability of the lifetime. Our data showed that heat treatment quite successfully eliminates post-irradiation changes in the response. Response measurements of the irradiated transistors, heat-treated and untreated, were carried out at room temperature over several weeks after irradiation to establish post-irradiation stability and assess if these transistors could be used for recording dose history. Calibration curves in the range 3-60 kGy for the thermally treated and untreated devices are presented. Dependence of the response of the transistors on the temperature of the measurements in the range 20-50 degrees C is reported
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