3,450 research outputs found
The Transversity Function and Double Spin Azimuthal Asymmetry in Semi-Inclusive Pion Leptoproduction
We show that the transverse momentum dependent transversity function is
proportional to the longitudinal polarization of a quark in a transversely
polarized proton. This result suggests an alternative, convenient method for
determining transversity, without knowing unusual fragmentation functions. The
method consists of measuring the double spin azimuthal asymmetry in
semi-inclusive pion leptoproduction by a transversely polarized proton target.
The asymmetry, which is twist 3, is estimated to be more than 10% under the
most favorable conditions. The experiment we suggest is feasible at facilities
like DESY and CERN.Comment: extended version; to appear on Int. Jou. Mod. Phys.
X-ray spectral evolution of the extragalactic Z-source, LMC X-2
We present the results obtained by a detailed study of the extragalactic Z
source, LMC X-2, using broad band Suzaku data and a large ( ksec)
data set obtained with the proportional counter array (PCA) onboard RXTE. The
PCA data allows for studying the complete spectral evolution along the
horizontal, normal and flaring branches of the Z-track. Comparison with
previous study show that the details of spectral evolution (like variation of
Comptonizing electron temperature), is similar to that of GX 17+2 but unlike
that of Cyg X-2 and GX 349+2. This suggests that Z sources are heterogeneous
group with perhaps LMC X-2 and GX 17+2 being member of a subclass. However non
monotonic evolution of the Compton y-parameter seems to be generic to all
sources. The broad band {\it Suzaku} data reveals that the additional soft
component of the source modelled as a disk blackbody emission is strongly
preferred over one where it is taken to be a blackbody spectrum. This component
as well as the temperature of seed photons do not vary when source goes into a
flaring mode and the entire variation can be ascribed to the Comptonizing
cloud. The bolometric unabsorbed luminosity of the source is well constrained
to be ergs/sec which if the source is Eddington
limited implies a neutron star mass of 1.6 M. We discuss the
implications of these results.Comment: 9 pages, 8 figures, accepted for the publicatin in MNRA
Evidence for a resonant cyclotron line in IGR J16493-4348 from the Swift-BAT hard X-ray survey
Resonant absorption cyclotron features are a key diagnostic tool to directly
measure the strength of the magnetic field of accreting neutron stars. However,
typical values for cyclotron features lie in the high-energy part of the
spectrum between 20 keV and 50 keV, where detection is often damped by the low
statistics from single pointed observations. We show that long-term monitoring
campaign performed with Swift-BAT of persistently, but faint, accreting
high-mass X-ray binaries is able to reveal in their spectra the presence of
cyclotron features. We extracted the average Swift-BAT 15-150 keV spectrum from
the 54 months long Swift-BAT survey of the high-mass X-ray source IGR
J16493-4348. To constrain the broadband spectrum we used soft X-ray spectra
from Swift-XRT and Suzaku pointed observations. We model the spectra using a
set of phenomenological models usually adopted to describe the energy spectrum
of accreting high-mass X-ray binaries; irrespective of the models we used, we
found significant improvements in the spectral fits adding to the models a
broad (10 keV width) absorption feature, with best-fitting energy estimate
between 30 and 33 keV, that we interpret as evidence for a resonant cyclotron
absorption feature. We also discuss instrumental issues related to the use of
Swift-BAT for this kind of studies and the statistical method to weight the
confidence level of this detection. Correcting for the gravitational redshift
of a 1.4 M_{\sun} neutron star, the inferred surface magnetic field is Bsurf
3.7 x 10^{12} Gauss. The spectral parameters of IGR J16493-4348 fit well with
empirical correlations observed when the whole sample of high-mass binaries
with detected cyclotron features is considered.Comment: Published in Astronomy & Astrophysics, 2011, 532, A7
Lymphocyte Subsets and Inflammatory Cytokines of Monoclonal Gammopathy of Undetermined Significance and Multiple Myeloma
Almost all multiple myeloma (MM) cases have been demonstrated to be linked to earlier monoclonal gammopathy of undetermined significance (MGUS). Nevertheless, there are no identified characteristics in the diagnosis of MGUS that have been helpful in differentiating subjects whose cancer may progress to a malignant situation. Regarding malignancy, the role of lymphocyte subsets and cytokines at the beginning of neoplastic diseases is now incontestable. In this review, we have concentrated our attention on the equilibrium between the diverse lymphocyte subsets and the cytokine system and summarized the current state of knowledge, providing an overview of the condition of the entire system in MGUS and MM. In an age where the therapy of neoplastic monoclonal gammopathies largely relies on drugs capable of acting on the immune system (immunomodulants, immunological checkpoint inhibitors, CAR-T), detailed knowledge of the the differences existing in benign and neoplastic forms of gammopathy is the main foundation for the adequate and optimal use of new drugs
Upper Palaeolithic hunter-gatherer subsistence in Mediterranean coastal environments: an isotopic study of the diets of earliest directlyt-dated humans from Sicily
The multifaceted role of vitamin b6 in cancer: drosophila as a model system to investigate dna damage
A perturbed uptake of micronutrients, such as minerals and vitamins, impacts on different human diseases, including cancer and neurological disorders. Several data converge towards a crucial role played by many micronutrients in genome integrity maintenance and in the establishment of a correct DNA methylation pattern. Failure in the proper accomplishment of these processes accelerates senescence and increases the risk of developing cancer, by promoting the formation of chromosome aberrations and deregulating the expression of oncogenes. Here, the main recent evidence regarding the impact of some B vitamins on DNA damage and cancer is summarized, providing an integrated and updated analysis, mainly centred on vitamin B6. In many cases, it is difficult to finely predict the optimal vitamin rate that is able to protect against DNA damage, as this can be influenced by a given individual's genotype. For this purpose, a precious resort is represented by model organisms which allow limitations imposed by more complex systems to be overcome. In this review, we show that Drosophila can be a useful model to deeply understand mechanisms underlying the relationship between vitamin B6 and genome integrity
Interpreting physical performance in professional soccer match-play: Should we be more pragmatic in our approach?
Academic and practitioner interest in the physical performance of male professional soccer players in the competition setting determined via time-motion analyses has grown substantially over the last four decades leading to a substantial body of published research and aiding development of a more systematic evidence-based framework for physical conditioning. Findings have forcibly shaped contemporary opinions in the sport with researchers and practitioners frequently emphasising the important role that physical performance plays in match outcomes. Time-motion analyses have also influenced practice as player conditioning programmes can be tailored according to the different physical demands identified across individual playing positions. Yet despite a more systematic approach to physical conditioning, data indicate that even at the very highest standards of competition, the contemporary player is still susceptible to transient and end-game fatigue. Over the course of this article, the author suggests that a more pragmatic approach to interpreting the current body of time-motion analysis data and its application in the practical setting is nevertheless required. Examples of this are addressed using findings in the literature to examine: a) the association between competitive physical performance and ‘success’ in professional soccer, b) current approaches to interpreting differences in time-motion analysis data across playing positions and, c) whether data can realistically be used to demonstrate the occurrence of fatigue in match-play. Gaps in the current literature and directions for future research are also identified
Fast UPLC/PDA determination of squalene in Sicilian P.D.O. pistachio from Bronte: optimization of oil extraction method and analytical characterization
A fast reversed-phase UPLC method was developed for squalene determination in Sicilian pistachio
samples that entry in the European register of the products with P.D.O. In the present study the SPE
procedure was optimized for the squalene extraction prior to the UPLC/PDA analysis. The precision
of the full analytical procedure was satisfactory and the mean recoveries were 92.8 + 0.3 % and
96.6 + 0.1 % for 25 and 50 mg L-1 level of addition, respectively. Selected chromatographic
conditions allowed a very fast squalene determination; in fact it was well separated in ~ 0.54 min
with good resolution. Squalene was detected in all the pistachio samples analyzed and the levels
ranged from 55.45 to 226.34 mg . kg-1. Comparing our results with those of other studies it emerges
that squalene contents in P.D.O. Sicilian pistachio samples, generally, were higher than those
measured for other samples of different geographic origins
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