288 research outputs found
Non-locality and Medium Effects in the Exclusive Photoproduction of Eta Mesons on Nuclei
A relativistic model for the quasifree exclusive photoproduction of
mesons on nuclei is extended to include both non-local and medium effects. The
reaction is assumed to proceed via the dominant contribution of the
S(1535) resonance. The complicated integrals resulting from the
non-locality are simplified using a modified version of a method given by
Cooper and Maxwell. The non-locality effects are found to affect the magnitude
of the cross section. Some possibilities reflecting the effects of the medium
on the propagation and properties of the intermediate S resonance are
studied. The effects of allowing the S to interact with the medium via
mean field scalar and vector potentials are considered. Both broadening of
width and reduction in mass of the resonance lead to a suppression of the
calculated cross sections.Comment: 19 pages, 7 figure
Direct Test of the Scalar-Vector Lorentz Structure of the Nucleon- and Antinucleon-Nucleus Potential
Quantum Hadrodynamics in mean field approximation describes the effective
nucleon-nucleus potential (about -50 MeV deep) as resulting from a strong
repulsive vector (about 400 MeV) and a strong attractive scalar (about -450
MeV) contribution. This scalar-vector Lorentz structure implies a significant
lowering of the threshold for photoproduction on a nucleus by about
850 MeV as compared to the free case since charge conjugation reverses the sign
of the vector potential contribution in the equation of motion for the
states. It also implies a certain size of the photon induced
pair creation cross section near threshold which is calculated for a
target nucleus Pb. We also indicate a measurable second signature of
the photoproduction process by estimating the increased cross
section for emission of charged pions as a consequence of
annihilation within the nucleus.Comment: 18 pages latex, 5 PS figure
Photoproduction of pi0-mesons from nuclei
Photoproduction of neutral pions from nuclei (carbon, calcium, niobium, lead)
has been studied for incident photon energies from 200 MeV to 800 MeV with the
TAPS detector using the Glasgow photon tagging spectrometer at the Mainz MAMI
accelerator. Data were obtained for the inclusive photoproduction of neutral
pions and the partial channels of quasifree single pi0, double pi0, and
pi0pi+/- photoproduction. They have been analyzed in terms of the in-medium
behavior of nucleon resonances and the pion - nucleus interaction. They are
compared to earlier measurements from the deuteron and to the predictions of a
Boltzmann-Uehling-Uhlenbeck (BUU) transport model for photon induced pion
production from nuclei.Comment: 15 pages, 22 figures, accepted for publication in EPJ
Pathogenesis of eosinophilic esophagitis: A comprehensive review of the genetic and molecular aspects
Eosinophilic esophagitis (EoE) is a relatively new condition described as an allergicmediated disease of the esophagus. Clinically, it is characterized by dysphagia, food impaction, and reflux-like symptoms. Multiple genome-wide association studies (GWAS) have been conducted to identify genetic loci associated with EoE. The integration of numerous studies investigating the genetic polymorphisms in EoE and the Mendelian diseases associated with EoE are discussed to provide insights into the genetic risk of EoE, notably focusing on CCL26 and CAPN14. We focus on the genetic loci investigated thus far, and their classification according to whether the function near the loci is known. The pathophysiology of EoE is described by separately presenting the known function of each cell and molecule, with the major contributors being eosinophils, Th2 cells, thymic stromal lymphopoietin (TSLP), transforming growth factor (TGF)-β1, and interleukin (IL)-13. This review aims to provide detailed descriptions of the genetics and the comprehensive pathophysiology of EoE
Proton polarizability effect in the Lamb shift of the hydrogen atom
The proton polarizability correction to the Lamb shift of electronic and
muonic hydrogen is calculated on the basis of isobar model and experimental
data on the structure functions of deep inelastic lepton-nucleon scattering.
The contributions of the Born terms, vector-meson exchanges and nucleon
resonances are taken into account in the construction of the photoabsorption
cross sections for transversely and longitudinally polarized virtual photons
sigma_{T,L}.Comment: 11 pages, 3 figure
Proton polarizability contribution to the hydrogen hyperfine splitting
The contribution of the proton polarizability to the hydrogen hyperfine
splitting is evaluated on the basis of modern experimental and theoretical
results on the proton polarized structure functions. The value of this
correction is equal to 1.4 ppm.Comment: 11 pages, LaTeX2.09, 7 figures, uses linedraw.sty, psfig.sty,
epsf.st
Hamiltonian submanifolds of regular polytopes
We investigate polyhedral -manifolds as subcomplexes of the boundary
complex of a regular polytope. We call such a subcomplex {\it -Hamiltonian}
if it contains the full -skeleton of the polytope. Since the case of the
cube is well known and since the case of a simplex was also previously studied
(these are so-called {\it super-neighborly triangulations}) we focus on the
case of the cross polytope and the sporadic regular 4-polytopes. By our results
the existence of 1-Hamiltonian surfaces is now decided for all regular
polytopes.
Furthermore we investigate 2-Hamiltonian 4-manifolds in the -dimensional
cross polytope. These are the "regular cases" satisfying equality in Sparla's
inequality. In particular, we present a new example with 16 vertices which is
highly symmetric with an automorphism group of order 128. Topologically it is
homeomorphic to a connected sum of 7 copies of . By this
example all regular cases of vertices with or, equivalently, all
cases of regular -polytopes with are now decided.Comment: 26 pages, 4 figure
Key Features Relevant to Select Antigens and TCR From the MHC-Mismatched Repertoire to Treat Cancer
Adoptive transfer of T cells transgenic for tumor-reactive T-cell receptors (TCR) is an attractive immunotherapeutic approach. However, clinical translation is so far limited due to challenges in the identification of suitable target antigens as well as TCRs that are concurrent safe and efficient. Definition of key characteristics relevant for effective and specific tumor rejection is essential to improve current TCR-based adoptive T-cell immunotherapies. We here characterized in-depth two TCRs derived from the human leukocyte antigen (HLA)-mismatched allogeneic repertoire targeting two different myeloperoxidase (MPO)-derived peptides presented by the same HLA-restriction element side by side comprising state of the art biochemical and cellular in vitro, in vivo, and in silico experiments. In vitro experiments reveal comparable functional avidities, off-rates, and cytotoxic activities for both TCRs. However, we observed differences especially with respect to cytokine secretion and cross-reactivity as well as in vivo activity. Biochemical and in silico analyses demonstrate different binding qualities of MPO-peptides to the HLA-complex determining TCR qualities. We conclude from our biochemical and in silico analyses of peptide-HLA-binding that rigid and high-affinity binding of peptides is one of the most important factors for isolation of TCRs with high specificity and tumor rejection capacity from the MHC-mismatched repertoire. Based on our results, we developed a workflow for selection of such TCRs with high potency and safety profile suitable for clinical translation
ACTA OTORHINOLARYNGOLOGICA ITALICA
Il presente studio retrospettivo a singolo cieco si pone come obbiettivo quello di valutare in che percentuale di casi di pazienti che si presentano con sintomatologia compatibile con neurite vestibolare acuta, con e senza perdita oggettiva della funzione vestibulare (VFL), sia presente un conflitto neurovascolare fra il nervo vestibolococleare e la arteria cerebellare anteroinferiore (AICA). 58 pazienti con sintomatologia suggestiva per neurite vestibolare acuta, valutati con RMN presso un centro di terzo livello, sono stati confrontati con 61 pazienti asintomatici. I radiologi hanno dato valutato la presenza di conflitto neurovascolare, in assenza di dati clinici, conferendo ai rilievi oggettivi una valutazione in una scala da 0 a 3 a seconda che il contatto fosse: nesuno; inferiore a 2 mm; superiore ai 2 mm; presenza di vacular loop. I reperti neurootologici sono stati quindi raccolti alloscuro del risultato dellimaging. La funzione vestibolare è stata testata con prova calorica bitermica. Alla prova calorica 26 casi (45%) hanno mostrato segni oggettivi di deficit vestibolare (Gruppo A), 32 casi (55%) non hanno invece mostrato alcun deficit labirintico (Gruppo B). Il gruppo A ha incluso 13 casi (50%) con evidenza di conflitto neurovascolare (NVC), il gruppo B ha incluso 26 casi con NVC (82%) (p = 0.012) mentre i controlli hanno incluso 16 casi con NVC (26%). La differenza fra i tre gruppi ha mostrato significatività statistica (p 0.05). I nostri dati indicano che la presenza di conflitti neurovascolari a livello dellangolo pontocerebellare è superiore in quei pazienti che in presenza di una sintomatologia compatibile con neurite vestibolare acuta abbiano una funzionalità simmetrica alla prova calorica
Relativistic quantum transport theory of hadronic matter: the coupled nucleon, delta and pion system
We derive the relativistic quantum transport equation for the pion
distribution function based on an effective Lagrangian of the QHD-II model. The
closed time-path Green's function technique, the semi-classical, quasi-particle
and Born approximation are employed in the derivation. Both the mean field and
collision term are derived from the same Lagrangian and presented analytically.
The dynamical equation for the pions is consistent with that for the nucleons
and deltas which we developed before. Thus, we obtain a relativistic transport
model which describes the hadronic matter with , and degrees
of freedom simultaneously. Within this approach, we investigate the medium
effects on the pion dispersion relation as well as the pion absorption and pion
production channels in cold nuclear matter. In contrast to the results of the
non-relativistic model, the pion dispersion relation becomes harder at low
momenta and softer at high momenta as compared to the free one, which is mainly
caused by the relativistic kinetics. The theoretically predicted free cross section is in agreement with the experimental data. Medium
effects on the cross section and momentum-dependent
-decay width are shown to be substantial.Comment: 66 pages, Latex, 12 PostScript figures included; replaced by the
revised version, to appear in Phys. Rev.
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