127 research outputs found
Nuclear Transparency to Intermediate-Energy Protons
Nuclear transparency in the (e,e'p) reaction for 135 < Tp < 800 MeV is
investigated using the distorted wave approximation. Calculations using
density-dependent effective interactions are compared with phenomenological
optical potentials. Nuclear transparency is well correlated with proton
absorption and neutron total cross sections. For Tp < 300 MeV there is
considerable sensitivity to the choice of optical model, with the empirical
effective interaction providing the best agreement with transparency data. For
Tp > 300 MeV there is much less difference between optical models, but the
calculations substantially underpredict transparency data and the discrepancy
increases with A. The differences between Glauber and optical model
calculations are related to their respective definitions of the semi-inclusive
cross section. By using a more inclusive summation over final states the
Glauber model emphasizes nucleon-nucleon inelasticity, whereas with a more
restrictive summation the optical model emphasizes nucleon-nucleus
inelasticity; experimental definitions of the semi-inclusive cross section lie
between these extremes.Comment: uuencoded gz-compressed tar file containing revtex and bbl files and
5 postscript figures, totalling 31 pages. Uses psfi
Semiclassical theory of surface plasmons in spheroidal clusters
A microscopic theory of linear response based on the Vlasov equation is
extended to systems having spheroidal equilibrium shape. The solution of the
linearized Vlasov equation, which gives a semiclassical version of the random
phase approximation, is studied for electrons moving in a deformed equilibrium
mean field. The deformed field has been approximated by a cavity of spheroidal
shape, both prolate and oblate. Contrary to spherical systems, there is now a
coupling among excitations of different multipolarity induced by the
interaction among constituents. Explicit calculations are performed for the
dipole response of deformed clusters of different size. In all cases studied
here the photoabsorption strength for prolate clusters always displays a
typical double-peaked structure. For oblate clusters we find that the
high--frequency component of the plasmon doublet can get fragmented in the
medium size region (). This fragmentation is related to the
presence of two kinds of three-dimensional electron orbits in oblate cavities.
The possible scaling of our semiclassical equations with the valence electron
number and density is investigated.Comment: 23 pages, 8 figures, revised version, includes discussion of scalin
Sensitivity of nucleon-nucleus scattering to the off-shell behavior of on-shell equivalent NN potentials
The sensitivity of nucleon-nucleus elastic scattering to the off-shell
behavior of realistic nucleon-nucleon interactions is investigated when
on-shell equivalent nucleon-nucleon potentials are used. The study is based on
applications of the full-folding optical model potential for an explicit
treatment of the off-shell behavior of the nucleon-nucleon effective
interaction. Applications were made at beam energies between 40 and 500 MeV for
proton scattering from 40Ca and 208Pb. We use the momentum-dependent Paris
potential and its local on-shell equivalent as obtained with the
Gelfand-Levitan and Marchenko inversion formalism for the two nucleon
Schroedinger equation. Full-folding calculations for nucleon-nucleus scattering
show small fluctuations in the corresponding observables. This implies that
off-shell features of the NN interaction cannot be unambiguously identified
with these processes. Inversion potentials were also constructed directly from
NN phase-shift data (SM94) in the 0-1.3 GeV energy range. Their use in
proton-nucleus scattering above 200 MeV provide a superior description of the
observables relative to those obtained from current realistic NN potentials.
Limitations and scope of our findings are presented and discussed.Comment: 17 pages tightened REVTeX, 8 .ps figures, submitted to Phys. Rev.
Microscopic calculations of medium effects for 200-MeV (p,p') reactions
We examine the quality of a G-matrix calculation of the effective
nucleon-nucleon (NN) interaction for the prediction of the cross section and
analyzing power for 200-MeV (p,p') reactions that populate natural parity
states in O, Si, and Ca. This calculation is based on a
one-boson-exchange model of the free NN force that reproduces NN observables
well. The G-matrix includes the effects of Pauli blocking, nuclear binding, and
strong relativistic mean-field potentials. The implications of adjustments to
the effective mass ansatz to improve the quality of the approximation at
momenta above the Fermi level will be discussed, along with the general quality
of agreement to a variety of (p,p') transitions.Comment: 36 pages, TeX, 18 figure
Functional approach to the electromagnetic response function: the Longitudinal Channel
In this paper we address the (charge) longitudinal electromagnetic response
for a homogeneous system of nucleons interacting via meson exchanges in the
functional framework. This approach warrants consistency if the calculation is
carried on order-by-order in the mesonic loop expansion with RPA-dressed
mesonic propagators. At the 1-loop order and considering pion, rho and omega
exchanges we obtain a quenching of the response, in line with the experimental
results.Comment: RevTeX, 18 figures available upon request - to be published in
Physical Review
Long-term adherence to IFN beta-1a treatment when using rebismart1device in patients with relapsing-remitting multiple sclerosis
The effectiveness of disease-modifying drugs in the treatment of multiple sclerosis is associated with adherence. RebiSmartÂź electronic device provides useful information about adherence to the treatment with subcutaneous (sc) interferon (IFN) Ă-1a (RebifÂź). The aim of the study was to determine long-term adherence to this treatment in patients with relapsing- remitting multiple sclerosis (RRMS). This retrospective multicentre observational study analysed 258 patients with RRMS who were receiving sc IFN Ă-1a (RebifÂź) treatment by using RebiSmartÂź until replacement (36 months maximum lifetime) or treatment discontinuation. Adherence was calculated with data (injection dosage, time, and date) automatically recorded by RebiSmartÂź. Patients in the study had a mean age of 41 years with a female proportion of 68%. Mean EDSS score at start of treatment was 1.8 (95% CI, 1.6-1.9). Overall adherence was 92.6%(95% CI, 90.6-94.5%). A total of 30.2% of patients achieved an adherence rate of 100%, 80.6% at least 90%, and only 13.2% of patients showed a suboptimal adherence (<80%). A total of 59.9% of subjects were relapse-free after treatment initiation. Among 106 subjects (41.1%) who experienced, on average, 1.4 relapses, the majority were mild (40.6%) or moderate (47.2%). Having experienced relapses from the beginning of the treatment was the only variable significantly related to achieving an adherence of at least 80% (OR = 3.06, 1.28-7.31). Results of this study indicate that sc IFN Ă-1a administration facilitated by RebiSmartÂź could lead to high rates of adherence to a prescribed dose regimen over 36 months
Baseline Inflammatory Status Reveals Dichotomic Immune Mechanisms Involved In Primary-Progressive Multiple Sclerosis Pathology
To ascertain the role of inflammation in the response to ocrelizumab in primary-progressive multiple sclerosis (PPMS).Multicenter prospective study including 69 patients with PPMS who initiated ocrelizumab treatment, classified according to baseline presence [Gd+, n=16] or absence [Gd-, n=53] of gadolinium-enhancing lesions in brain MRI. Ten Gd+ (62.5%) and 41 Gd- patients (77.4%) showed non-evidence of disease activity (NEDA) defined as no disability progression or new MRI lesions after 1 year of treatment. Blood immune cell subsets were characterized by flow cytometry, serum immunoglobulins by nephelometry, and serum neurofilament light-chains (sNfL) by SIMOA. Statistical analyses were corrected with the Bonferroni formula.More than 60% of patients reached NEDA after a year of treatment, regardless of their baseline characteristics. In Gd+ patients, it associated with a low repopulation rate of inflammatory B cells accompanied by a reduction of sNfL values 6 months after their first ocrelizumab dose. Patients in Gd- group also had low B cell numbers and sNfL values 6 months after initiating treatment, independent of their treatment response. In these patients, NEDA status was associated with a tolerogenic remodeling of the T and innate immune cell compartments, and with a clear increase of serum IgA levels.Baseline inflammation influences which immunological pathways predominate in patients with PPMS. Inflammatory B cells played a pivotal role in the Gd+ group and inflammatory T and innate immune cells in Gd- patients. B cell depletion can modulate both mechanisms.Copyright © 2022 FernĂĄndez-Velasco, Monreal, Kuhle, Meca-Lallana, Meca-Lallana, Izquierdo, Oreja-Guevara, GascĂłn-GimĂ©nez, Sainz de la Maza, Walo-Delgado, Lapuente-Suanzes, Maceski, RodrĂguez-MartĂn, RoldĂĄn, Villarrubia, Saiz, Blanco, Diaz-PĂ©rez, Valero-LĂłpez, Diaz-Diaz, Aladro, Brieva, Ăñiguez, GonzĂĄlez-SuĂĄrez, RodrĂguez de Antonio, GarcĂa-DomĂnguez, Sabin, Llufriu, Masjuan, Costa-Frossard and Villar
Effectiveness of the psychological and pharmacological treatment of catastrophization in patients with fibromyalgia: a randomized controlled trial
<p>Abstract</p> <p>Background</p> <p>Fibromyalgia is a prevalent and disabling disorder characterized by widespread pain and other symptoms such as insomnia, fatigue or depression. Catastrophization is considered a key clinical symptom in fibromyalgia; however, there are no studies on the pharmacological or psychological treatment of catastrophizing. The general aim of this study is to assess the effectiveness of cognitive-behaviour therapy and recommended pharmacological treatment for fibromyalgia (pregabalin, with duloxetine added where there is a comorbid depression), compared with usual treatment at primary care level.</p> <p>Method/design</p> <p><it>Design</it>: A multi-centre, randomized controlled trial involving three groups: the control group, consisting of usual treatment at primary care level, and two intervention groups, one consisting of cognitive-behaviour therapy, and the other consisting of the recommended pharmacological treatment for fibromyalgia.</p> <p><it>Setting</it>: 29 primary care health centres in the city of Zaragoza, Spain.</p> <p><it>Sample</it>: 180 patients, aged 18â65 years, able to understand and read Spanish, who fulfil criteria for primary fibromyalgia, with no previous psychological treatment, and no pharmacological treatment or their acceptance to discontinue it two weeks before the onset of the study.</p> <p><it>Intervention</it>: Psychological treatment is based on the manualized protocol developed by Prof. Escobar et al, from the University of New Jersey, for the treatment of somatoform disorders, which has been adapted by our group for the treatment of fibromyalgia. It includes 10 weekly sessions of cognitive-behaviour therapy. Pharmacological therapy consists of the recommended pharmacological treatment for fibromyalgia: pregabalin (300â600 mg/day), with duloxetine (60â120 mg/day) added where there is a comorbid depression).</p> <p><it>Measurements</it>: The following socio-demographic data will be collected: sex, age, marital status, education, occupation and social class. The diagnosis of psychiatric disorders will be made with the Structured Polyvalent Psychiatric Interview. Other instruments to be administered are the Pain Catastrophizing Scale, the Hamilton tests for Anxiety and for Depression, the Fibromyalgia Impact Questionnaire (FIQ), the EuroQuol-5 domains (EQ-5D), and the use of health and social services (CSRI). Assessments will be carried out at baseline, 1, 3, and 6 months.</p> <p><it>Main variable</it>: Pain catastrophizing.</p> <p><it>Analysis</it>: The analysis will be per intent to treat. We will use the general linear models of the SPSS version 15 statistical package, to analyse the effect of the treatment on the result variable (pain catastrophizing).</p> <p>Discussion</p> <p>It is necessary to assess the effectiveness of pharmacological and psychological treatments for pain catastrophizing in fibromyalgia. This randomized clinical trial will determine whether both treatments are effective for this important prognostic variable in patients with fibromyalgia.</p> <p>Trial registration</p> <p>Current Controlled Trials ISRCTN10804772</p
Primate TNF Promoters Reveal Markers of Phylogeny and Evolution of Innate Immunity
Background. Tumor necrosis factor (TNF) is a critical cytokine in the immune response whose transcriptional activation is controlled by a proximal promoter region that is highly conserved in mammals and, in particular, primates. Specific single nucleotide polymorphisms (SNPs) upstream of the proximal human TNF promoter have been identified, which are markers of human ancestry.
Methodology/Principal findings. Using a comparative genomics approach we show that certain fixed genetic differences in the TNF promoter serve as markers of primate speciation. We also demonstrate that distinct alleles of most human TNF promoter SNPs are identical to fixed nucleotides in primate TNF promoters. Furthermore, we identify fixed genetic differences within the proximal TNF promoters of Asian apes that do not occur in African ape or human TNF promoters. Strikingly, protein-DNA binding assays and gene reporter assays comparing these Asian ape TNF promoters to African ape and human TNF promoters demonstrate that, unlike the fixed differences that we define that are associated with primate phylogeny, these Asian ape-specific fixed differences impair transcription factor binding at an Sp1 site and decrease TNF transcription induced by bacterial stimulation of macrophages.
Conclusions/significance. Here, we have presented the broadest interspecies comparison of a regulatory region of an innate immune response gene to date. We have characterized nucleotide positions in Asian ape TNF promoters that underlie functional changes in cell type- and stimulus-specific activation of the TNF gene. We have also identified ancestral TNF promoter nucleotide states in the primate lineage that correspond to human SNP alleles. These findings may reflect evolution of Asian and African apes under a distinct set of infectious disease pressures involving the innate immune response and TNF
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