8,817 research outputs found
The pairing Hamiltonian for one pair of identical nucleons bound in a potential well
The problem of one pair of identical nucleons sitting in single
particle levels of a potential well and interacting through the pairing force
is treated introducing even Grassmann variables. The eigenvectors are
analytically expressed solely in terms of these with coefficients fixed by the
eigenvalues and the single particle energies. When the latter are those of an
harmonic oscillator well an accurate expression is derived for both the
collective eigenvalue and for those trapped in between the single particle
levels, for any strength of the pairing interaction and for any number of
levels. Notably the trapped solutions are labelled through an index upon which
they depend parabolically.Comment: 5 pages, 1 postscript figur
An Integrated Picture of Star Formation, Metallicity Evolution, and Galactic Stellar Mass Assembly
We present an integrated study of star formation and galactic stellar mass
assembly from z=0.05-1.5 and galactic metallicity evolution from z=0.05-0.9
using a very large and highly spectroscopically complete sample selected by
rest-frame NIR bolometric flux in the GOODS-N. We assume a Salpeter IMF and fit
Bruzual & Charlot (2003) models to compute the galactic stellar masses and
extinctions. We determine the expected formed stellar mass density growth rates
produced by star formation and compare them with the growth rates measured from
the formed stellar mass functions by mass interval. We show that the growth
rates match if the IMF is slightly increased from the Salpeter IMF at
intermediate masses (~10 solar masses). We investigate the evolution of galaxy
color, spectral type, and morphology with mass and redshift and the evolution
of mass with environment. We find that applying extinction corrections is
critical when analyzing galaxy colors; e.g., nearly all of the galaxies in the
green valley are 24um sources, but after correcting for extinction, the bulk of
the 24um sources lie in the blue cloud. We find an evolution of the
metallicity-mass relation corresponding to a decrease of 0.21+/-0.03 dex
between the local value and the value at z=0.77 in the 1e10-1e11 solar mass
range. We use the metallicity evolution to estimate the gas mass of the
galaxies, which we compare with the galactic stellar mass assembly and star
formation histories. Overall, our measurements are consistent with a galaxy
evolution process dominated by episodic bursts of star formation and where star
formation in the most massive galaxies (>1e11 solar masses) ceases at z<1.5
because of gas starvation. (Abstract abridged)Comment: 48 pages, Accepted by the Astrophysical Journa
Controlled Release of Tramadol from Mixed Matrix Membranes
In this work mixed matrix membranes (zeolite loaded) were prepared and tested as potential devices for the controlled release of tramadol hydrochloride. Due to the hydrophilic nature of the drug, a hydrophobic polymer (polydimethylsiloxane) was chosen for the membrane preparation. NaX zeolites was added to PDMS matrix as modulating agent with the aim to obtain a linear and adequate delivery of the drug in the time as required by the therapeutic needs of this opioid.
About the different investigated systems, the PDMS membrane containing 17 wt% of zeolite and 0.2 wt% of drug seems to be the most promising for application as transdermal device. Different mathematical models (Zero order, First order, Higuchi, Bhaskar, and Korsemeyer-Peppas) were used to interpret the drug release mechanism from the different Mixed matrix membranes. The experimental data showed good fit with three different models: Higuchi, Bhaskar and Korsemeyer-Peppas
Circulating SIRT1 inversely correlates with epicardial fat thickness in patients with obesity
Background and aim: Obesity is increasing worldwide and is related to undesirable cardiovascular outcomes. Epicardial fat (EF), the heart visceral fat depot, increases with obesity and correlates with cardiovascular risk. SIRT1, an enzyme regulating metabolic circuits linked with obesity, has a cardioprotective effect and is a predictor of cardiovascular events. We aimed to assess the relationship of EF thickness (EFT) with circulating SIRT1 in patients with obesity.
Methods and results: Sixty-two patients affected by obesity and 23 lean controls were studied. Plasma SIRT1 concentration was determined by enzyme-linked immunosorbent assay (ELISA). EFT was measured by echocardiography. Body mass index (BMI), waist circumference, heart rate (HR), blood pressure, and laboratory findings (fasting glucose, insulin, HbA1c, cholesterol, and triglycerides) were assessed. SIRT1 was significantly lower (P = 0.002) and EFT was higher (P < 0.0001) in patients with obesity compared with lean controls. SIRT1 showed a negative correlation with EFT and HR in the obesity group (rho = -0.350, P = 0.005; rho = -0.303, P = 0.008, respectively). After adjustment for obesity-correlated variables, multiple linear regression analysis showed that EFT remained the best correlate of SIRT1 (beta = -0.352, P = 0.016).
Conclusions: Circulating SIRT1 correlates with the visceral fat content of the heart. Serum SIRT1 levels might provide additional information for risk assessment of coronary artery disease in patients with obesity. (C) 2016 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved
Relativistic Hamiltonians in many-body theories
We discuss the description of a many-body nuclear system using Hamiltonians
that contain the nucleon relativistic kinetic energy and potentials with
relativistic corrections. Through the Foldy-Wouthuysen transformation, the
field theoretical problem of interacting nucleons and mesons is mapped to an
equivalent one in terms of relativistic potentials, which are then expanded at
some order in 1/m_N. The formalism is applied to the Hartree problem in nuclear
matter, showing how the results of the relativistic mean field theory can be
recovered over a wide range of densities.Comment: 14 pages, uses REVTeX and epsfig, 3 postscript figures; a postscript
version of the paper is available by anonymous ftp at
ftp://carmen.to.infn.it/pub/depace/papers/951
Ancestral function of the phytochelatin synthase C-terminal domain in inhibition of heavy metal-mediated enzyme overactivation
Phytochelatin synthases (PCSs) play essential roles in detoxification of a broad range of heavy metals in plants and
other organisms. Until now, however, no PCS gene from liverworts, the earliest branch of land plants and possibly the
first one to acquire a PCS with a C-terminal domain, has been characterized. In this study, we isolated and functionally characterized the first PCS gene from a liverwort, Marchantia polymorpha (MpPCS). MpPCS is constitutively expressed in all organs examined, with stronger expression in thallus midrib. The gene expression is repressed by Cd2+
and Zn2+. The ability of MpPCS to increase heavy metal resistance in yeast and to complement cad1-3 (the null mutant
of the Arabidopsis ortholog AtPCS1) proves its function as the only PCS from M. polymorpha. Site-directed mutagenesis of the most conserved cysteines of the C-terminus of the enzyme further uncovered that two twin-cysteine motifs
repress, to different extents, enzyme activation by heavy metal exposure. These results highlight an ancestral function
of the PCS elusive C-terminus as a regulatory domain inhibiting enzyme overactivation by essential and non-essential
heavy metals. The latter finding may be relevant for obtaining crops with decreased root to shoot mobility of cadmium,
thus preventing its accumulation in the food chain
Inelastic electron-nucleus scattering and scaling at high inelasticity
Highly inelastic electron scattering is analyzed within the context of the
unified relativistic approach previously considered in the case of quasielastic
kinematics. Inelastic relativistic Fermi gas modeling that includes the
complete inelastic spectrum - resonant, non-resonant and Deep Inelastic
Scattering - is elaborated and compared with experimental data. A
phenomenological extension of the model based on direct fits to data is also
introduced. Within both models, cross sections and response functions are
evaluated and binding energy effects are analyzed. Finally, an investigation of
the second-kind scaling behavior is also presented.Comment: 39 pages, 13 figures; formalism extended and slightly reorganized,
conclusions extended; to appear in Phys. Rev.
Hoarding disorder: A new obsessive-compulsive related disorder in DSM-5
Obsessive-compulsive disorder (OCD) and related disorders have been the subject of significant revisions in the fifth edition of the Diagnostic and Statistical Manual (DSM-5). One of these major changes has been the removal of OCD from the \u2018Anxi- ety Disorders\u2019 section and its instalment in a new and distinct Obsessive-Compulsive and Related Disorders (OCRDs) chap- ter. However, it is the instatement of Hoarding Disorder (HD) as a new OCRD that marks the most significant change. Previously considered a symptom of OCPD, and subsequently linked to OCD, it is now acknowledged that hoarding can emerge inde- pendently from any alternative condition. The present paper provides an updated review of recent investigations supporting the status of HD as an independent nosological entity. Specifi- cally, we will present the new DSM-5 diagnostic criteria and examine the literature pertaining to the psychopathological and phenomenological aspects of the disorder, with particular atten- tion to practical strategies that can help clinicians to recognise and differentiate HD from OCD. Finally, the available assess- ment and treatment strategies for HD are summarised
Glucose-Coated Superparamagnetic Iron Oxide Nanoparticles Prepared by Metal Vapour Synthesis Are Electively Internalized in a Pancreatic Adenocarcinoma Cell Line Expressing GLUT1 Transporter
Iron oxide nanoparticles (IONP) can have a variety of biomedical applications due to their visualization properties through Magnetic Resonance Imaging (MRI) and heating with radio frequency or alternating magnetic fields. In the oncological field, coating IONP with organic compounds to provide specific features and to achieve the ability of binding specific molecular targets appears to be very promising. To take advantage of the high avidity of tumor cells for glucose, we report the development of very small glucose-coated IONP (glc-IONP) by employing an innovative technique, Metal Vapor Synthesis (MVS). Moreover, we tested the internalization of our gl-IONP on a tumor line, BxPC3, over-expressing GLUT 1 transporter. Both glc-IONP and polyvinylpyrrolidone-IONP (PVP-IONP), as control, were prepared with MVS and were tested on BxPC3 at various concentrations. To evaluate the role of GLUT-1 transporter, we also investigated the effect of adding a polyclonal anti-GLUT1 antibody. After proper treatment, the iron value was assessed by atomic absorption spectrometer, reported in mcg/L and expressed in mg of protein. Our IONP prepared with MVS were very small and homogeneously distributed in a narrow range (1.75-3.75 nm) with an average size of 2.7 nm and were super-paramagnetic. Glc-IONP were internalized by BxPC3 cells in a larger amount than PVP-IONP. After 6h of treatment with 50 mcg/mL of IONPs, the content of Fe was 1.5 times higher in glc-IONP-treated cells compared with PVP-IONP-treated cells. After 1h pre-treatment with anti-GLUT1, a reduction of 41% cellular accumulation of glc-IONP was observed. Conversely, the uptake of PVP-IONPs was reduced only by 14% with antibody pretreatment. In conclusion, MVS allowed us to prepare small, homogeneous, super-paramagnetic glc-IONP, which are electively internalized by a tumor line over-expressing GLUT1. Our glc-IONP appear to have many requisites for in vivo use
Parton Distributions Working Group
The main focus of this working group was to investigate the different issues
associated with the development of quantitative tools to estimate parton
distribution functions uncertainties. In the conclusion, we introduce a
"Manifesto" that describes an optimal method for reporting data.Comment: Report of the Parton Distributions Working Group of the 'QCD and Weak
Boson Physics workshop in preparation for Run II at the Fermilab Tevatron'.
Co-Conveners: L. de Barbaro, S.A. Keller, S. Kuhlmann, H. Schellman, and
W.-K. Tun
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