489 research outputs found
Correlation of the humoral immune answer to selected bacterial antigens with presence of the DNA specific to Salmonella enteritidis after amplification by PCR
Deep electrical resistivity structure of northwestern Costa Rica
First long-period magnetotelluric investigations were conducted in early 2008 in northwestern Costa Rica, along a profile that extends from the coast of the Pacific Ocean, traverses the volcanic arc and ends currently at the Nicaraguan border. The aim of this study is to gain insight into the electrical resistivity structure and thus fluid distribution at the continental margin where the Cocos plate subducts beneath the Caribbean plate. Preliminary two-dimensional models map the only moderately resistive mafic/ultramafic complexes of the Nicoya Peninsula (resistivity of a few hundred Ωm), the conductive forearc and the backarc basins (several Ωm). Beneath the backarc basin the data image a poor conductor in the basement with a clear termination in the south, which may tentatively be interpreted as the Santa Elena Suture. The volcanic arc shows no pronounced anomaly at depth, but a moderate conductor underlies the backarc with a possible connection to the upper mantle. A conductor at deep-crustal levels in the forearc may reflect fluid release from the downgoing slab
The Role of the D13 (1520) Resonance in eta Electroproduction
We investigate the electroproduction of eta mesons below a center of momentum
energy of 1.6 GeV, with particular emphasis on the roles of the N*(1535) and
N*(1520) resonances. Using the effective Lagrangian approach, we show that the
transverse helicity amplitude of the N*(1535) can be extracted with good
accuracy from the new eta electroproduction data, under reasonable assumptions
for the strength of the longitudinal helicity amplitude. In addition, although
the differential cross section is found to to have a small sensitivity to the
N*(1520) resonance, it is shown that a recently completed double polarization
experiment is very sensitive to this resonance.Comment: 7 pages, Revtex, 3 figure
On astrophysical solution to ultra high energy cosmic rays
We argue that an astrophysical solution to UHECR problem is viable. The
pectral features of extragalactic protons interacting with CMB are calculated
in model-independent way. Using the power-law generation spectrum as the only assumption, we analyze four features of the proton
spectrum: the GZK cutoff, dip, bump and the second dip. We found the dip,
induced by electron-positron production on CMB, as the most robust feature,
existing in energy range eV. Its shape is
stable relative to various phenomena included in calculations. The dip is well
confirmed by observations of AGASA, HiRes, Fly's Eye and Yakutsk detectors. The
best fit is reached at , with the allowed range 2.55 - 2.75. The
dip is used for energy calibration of the detectors. After the energy
calibration the fluxes and spectra of all three detectors agree perfectly, with
discrepancy between AGASA and HiRes at eV being not
statistically significant. The agreement of the dip with observations should be
considered as confirmation of UHE proton interaction with CMB. The dip has two
flattenings. The high energy flattening at eV
automatically explains ankle. The low-energy flattening at eV provides the transition to galactic cosmic rays. This transition is
studied quantitatively. The UHECR sources, AGN and GRBs, are studied in a
model-dependent way, and acceleration is discussed. Based on the agreement of
the dip with existing data, we make the robust prediction for the spectrum at
eV to be measured in the nearest future by
Auger detector.Comment: Revised version as published in Phys.Rev. D47 (2006) 043005 with a
small additio
Photo- and Electron-Production of Mesons on Nucleons and Nuclei
In these lectures I will show some results obtained with the chiral unitary
approach applied to the photo and electroproduction of mesons. The results for
photoproduction of and , together with
related reactions will be shown, having with common denominator the excitation
of the resonance which is one of those dynamically generated in
the chiral unitary approach. Then I will show results obtained for the reaction which reproduce the bulk of the data except for a
pronounced peak, giving support to a new mesonic resonance, X(2175). Results
will also be shown for the electromagnetic form factors of the
resonance, also dynamically generated in this approach. Finally, I will show
some results on the photoproduction of the in nuclei, showing that
present experimental results claiming a shift of the mass in the
medium are tied to a particular choice of background and are not conclusive.
One the other hand, the same experimental results show unambiguously a huge
increase of the width in the nuclear medium.Comment: Lecture at the "International School of Nuclear Physics", 29th Course
Quarks in Hadrons and Nuclei, Erice, Italy, September 2007. Note added in
Proofs concerning the mixed events technique and other comments on omega
productio
Imaging thrombosis with 99mTc-labeled RAM.1-antibody in vivo.
Platelets play a major role in thrombo-embolic diseases, notably by forming a thrombus that can ultimately occlude a vessel. This may provoke ischemic pathologies such as myocardial infarction, stroke or peripheral artery diseases, which represent the major causes of death worldwide. The aim of this study was to evaluate the specificity of radiolabeled Rat-Anti-Mouse antibody (RAM.1).We describe a method to detect platelets by using a RAM.1 coupled with the chelating agent hydrazinonicotinic acid (HYNIC) conjugated toWe demonstrated a quick and strong affinity of the radiolabeled RAM.1 for the platelet thrombus. Results clearly demonstrated the ability of this radioimmunoconjugate for detecting thrombi from 10 min post injection with an exceptional thrombi uptake. Using FeClThanks to the high sensitivity of SPECT, we provided evidence that [journal articleresearch support, non-u.s. gov't2018 062018 03 17importe
Parity-Violating Excitation of the \Delta(1232): Hadron Structure and New Physics
We consider prospects for studying the parity-violating (PV) electroweak
excitation of the \Delta(1232) resonance with polarized electron scattering.
Given present knowledge of Standard Model parameters, such PV experiments could
allow a determination of the N -> \Delta electroweak helicity amplitudes. We
discuss the experimental feasibility and theoretical interpretability of such a
determination as well as the prospective implications for hadron structure
theory. We also analyze the extent to which a PV N -> \Delta measurement could
constrain various extensions of the Standard Model.Comment: 43 pages, RevTex, 8 PS figures, uses epsf.sty, rotate.sty, version to
appear in Nucl. Phys. A, main points emphasized, some typos correcte
Hadronic properties of the S_{11}(1535) studied by electroproduction off the deuteron
Properties of excited baryonic states are investigated in the context of
electroproduction of baryon resonances off the deuteron. In particular, the
hadronic radii and the compositeness of baryon resonances are studied for
kinematic situations in which their hadronic reinteraction is the dominant
contribution. Specifically, we study the reaction at for kinematics in which the produced hadronic state reinteracts
predominantly with the spectator nucleon. A comparison of constituent quark
model and effective chiral Lagrangian calculations of the shows
substantial sensitivity to the structure of the produced resonance.Comment: 24 pages, 5 figure
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