5,995 research outputs found
Electromagnetic nucleon form factors in instant and point form
We present a study of the electromagnetic structure of the nucleons with
constituent quark models in the framework of relativistic quantum mechanics. In
particular, we address the construction of spectator-model currents in the
instant and point forms. Corresponding results for the elastic nucleon
electromagnetic form factors as well as charge radii and magnetic moments are
presented. We also compare results obtained by different realistic nucleon wave
functions stemming from alternative constituent quark models. Finally, we
discuss the theoretical uncertainties that reside in the construction of
spectator-model transition operators.Comment: 13 pages, 9 figures, updated and extended version for publicatio
Structure function of a damped harmonic oscillator
Following the Caldeira-Leggett approach to describe dissipative quantum
systems the structure function for a harmonic oscillator with Ohmic dissipation
is evaluated by an analytic continuation from euclidean to real time. The
analytic properties of the Fourier transform of the structure function with
respect to the energy transfer (the ``characteristic function'') are studied
and utilized. In the one-parameter model of Ohmic dissipation we show
explicitly that the broadening of excited states increases with the state
number without violating sum rules. Analytic and numerical results suggest that
this is a phenomenologically relevant, consistent model to include the coupling
of a single (sub-)nuclear particle to unobserved and complex degrees of
freedom.Comment: 23 pages, 5 figures, RevTex4, minor changes following referee's
comments and by PRC: the definite article in the original title has been
droppe
Beta defensin-2 is reduced in central but not in distal airways of smoker COPD patients
Background: Altered pulmonary defenses in chronic obstructive pulmonary disease (COPD) may promote distal airways bacterial colonization. The expression/activation of Toll Like receptors (TLR) and beta 2 defensin (HBD2) release by epithelial cells crucially affect pulmonary defence mechanisms. Methods: The epithelial expression of TLR4 and of HBD2 was assessed in surgical specimens from current smokers COPD (s-COPD; n = 17), ex-smokers COPD (ex-s-COPD; n = 8), smokers without COPD (S; n = 12), and from non-smoker non-COPD subjects (C; n = 13). Results: In distal airways, s-COPD highly expressed TLR4 and HBD2. In central airways, S and s-COPD showed increased TLR4 expression. Lower HBD2 expression was observed in central airways of s-COPD when compared to S and to ex-s-COPD. s-COPD had a reduced HBD2 gene expression as demonstrated by real-time PCR on micro-dissected bronchial epithelial cells. Furthermore, HBD2 expression positively correlated with FEV1/FVC ratio and inversely correlated with the cigarette smoke exposure. In a bronchial epithelial cell line (16 HBE) IL-1β significantly induced the HBD2 mRNA expression and cigarette smoke extracts significantly counteracted this IL-1 mediated effect reducing both the activation of NFkB pathway and the interaction between NFkB and HBD2 promoter. Conclusions: This study provides new insights on the possible mechanisms involved in the alteration of innate immunity mechanisms in COPD. © 2012 Pace et al
Quasielastic K-nucleus scattering
Quasielastic K^+ - nucleus scattering data at q=290, 390 and 480 MeV/c are
analyzed in a finite nucleus continuum random phase approximation framework,
using a density-dependent particle-hole interaction. The reaction mechanism is
consistently treated according to Glauber theory, keeping up to two-step
inelastic processes. A good description of the data is achieved, also providing
a useful constraint on the strength of the effective particle-hole interaction
in the scalar-isoscalar channel at intermediate momentum transfers. We find no
evidence for the increase in the effective number of nucleons participating in
the reaction which has been reported in the literature.Comment: 21 pages, uses REVTeX and epsfig, 9 postscript figures; replaced
version corrects a few minor errors in the tex
Idaho National Laboratory Cultural Resource Management Office FY 2011 Activity Report
The Idaho National Laboratory (INL) Site is home to vast numbers and a wide variety of important cultural resources representing at least a 13,500 year span of human land use in the region. As a federal agency, the Department of Energy, Idaho Operations Office (DOE-ID) has legal responsibility for the management and protection of the resources and has contracted these responsibilities to Battelle Energy Alliance (BEA). The BEA professional staff is committed to maintaining a cultural resource management program that accepts the challenge of preserving INL cultural resources in a manner reflecting their importance in local, regional, and national history. This report is intended as a stand-alone document that summarizes activities performed by the INL Cultural Resource Management Office (CRMO) staff during fiscal year 2011. This work is diverse, far-reaching and though generally confined to INL cultural resource compliance, also includes a myriad of professional and voluntary community activities. This document is intended to be informative to both internal and external stakeholders, serve as a planning tool for future INL cultural resource management work, and meet an agreed upon legal requirement
Electroexcitation of the P33(1232), P11(1440), D13(1520), S11(1535) at Q^2=0.4 and 0.65(GeV/c)^2
Using two approaches: dispersion relations and isobar model, we have analyzed
recent high precision CLAS data on cross sections of \pi^0, \pi^+, and \eta
electroproduction on protons, and the longitudinally polarized electron beam
asymmetry for p(\vec{e},e'p)\pi^0 and p(\vec{e},e'n)\pi^+. The contributions of
the resonances P33(1232), P11(1440), D13(1520), S11(1535) to \pi
electroproduction and S11(1535) to \eta electroproduction are found. The
results obtained in the two approaches are in good agreement with each other.
There is also good agreement between amplitudes of the \gamma^* N \to S11(1535)
transition found in \pi and \eta electroproduction. For the first time accurate
results are obtained for the longitudinal amplitudes of the P11(1440),
D13(1520) and S11(1535) electroexcitation on protons.Comment: 9 pages, 9 figure
Hadron and Quark Form Factors in the Relativistic Harmonic Oscillator Model
Nucleon, pion and quark form factors are studied within the relativistic
harmonic oscillator model including the quark spin. It is shown that the
nucleon charge, magnetic and axial form factors and the pion charge form factor
can be explained with one oscillator parameter if one accounts for the scaling
rule and the size of the constituent quarks.Comment: 9 pages, Latex, 3 postscript figures, DFTT 8/9
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