97 research outputs found
Medium Effects in DIS from Polarized Nuclear Targets
The behavior of the nucleon structure functions in lepton nuclei deep
inelastic scattering, both polarized and unpolarized, due to nuclear structure
effects is reanalyzed. The study is performed in two schemes: an x-rescaling
approach, and one in which there is an increase of sea quark components in the
in medium nucleon, related to the low energy N-N interaction. In view of a
recent interesting experimental proposal to study the behavior of the proton
spin structure functions in nuclei we proceed to compare these approaches in an
effort to enlighten the possible phenomenological interest of such difficult
experiment.Comment: 11 pages and 5 figure
Interference effects in the Coulomb dissociation of 15,17,19C
In this work the semiclassical model of pure Coulomb excitation was applied
to the breakup of 15,17,19C. The ground state wave functions were calculated in
the particle-rotor model including core excitation. The importance of
interference terms in the dipole strength arising after including core degrees
of freedom is analyzed for each isotope. It is shown that Coulomb interference
effects are important for the case of 17C.Comment: 17 pages, 5 figures accepted to Physical Review
Nuclear response to dark matter signals in Ge and Xe odd-mass targets
Abstract: The interaction of dark matter particles (WIMPs) with the odd-mass
Ge and Xe target nuclei ,{ {that is the recoil rates
corresponding to the elastic scattering of WIMPs by these nuclei}}, is analysed
in the context of the minimal extensions of the SUSY model. The BCS+QRPA
technique plus the quasiparticle-phonon coupling scheme is used to describe the
nuclear structure part of the calculations. The resulting values for the
nuclear spin content of both nuclei are compared to values previously reported
in the literature
Testing hadronic interaction packages at cosmic ray energies
A comparative analysis of the secondary particles output of the main hadronic
interaction packages used in simulations of extensive air showers is presented.
Special attention is given to the study of events with very energetic leading
secondary particles, including diffractive interactions
Allelic and epigenetic DNA variation in relation to F1 heterosis manifestation in F1 hybrids of Capsicum annuum L.
Managing F1 heterosis is one of the major objectives in hybrid crop breeding programs. The classical theory considers the heterozygosity in F1 hybrids to be the main factor contributing to heterosis and therefore presumes a linear relationship between the value of genetic polymorphisms in parental lines and the heterotic response of their F1 offspring. Therefore, the genetic diversity information is viewed as a tool for selection of promising cross-combinations, but results published by different researchers are inconsistent. In this work, we studied the contributions of structural and nonstructural DNA polymorphisms to F1 heterosis manifestation. We used SSR and methyl-sensitive AFLP (MSAP with HpaII and MspI izoshisomers) protocols for obtaining specific patterns for heterotic and nonheterotic F1 hybrids of sweet pepper (Capsicum annuum L.) from a Belarusian breeding program. We found out that a certain portion of heterosis for yield-related traits might be explained by the polymorphism revealed by SSR analysis. According to our data, the total number of polymorphic SSR loci and the ratio of polymorphic and nonpolymorphic loci demonstrate a significant predictive value and can serve as additional prognostic criteria for the selection of promising cross-combinations. From the MSAP assay, we found a relationship between heterosis and the numbers of methylated and nonmethylated DNA loci for yield traits. Our results indicate that cross-hybridization may favor epiallelic modifications in F1 hybrids, presumably responsible for heterosis. Thus, epigenetic DNA variation may explain the absence of a linear relationship between the level of structural DNA divergence and F1 heterosis, as well as the manifestation of heterosis in crosses of related (genetically similar) accessions
Measurement of the Depth of Maximum of Extensive Air Showers above 10^18 eV
We describe the measurement of the depth of maximum, Xmax, of the
longitudinal development of air showers induced by cosmic rays. Almost four
thousand events above 10^18 eV observed by the fluorescence detector of the
Pierre Auger Observatory in coincidence with at least one surface detector
station are selected for the analysis. The average shower maximum was found to
evolve with energy at a rate of (106 +35/-21) g/cm^2/decade below 10^(18.24 +/-
0.05) eV and (24 +/- 3) g/cm^2/decade above this energy. The measured
shower-to-shower fluctuations decrease from about 55 to 26 g/cm^2. The
interpretation of these results in terms of the cosmic ray mass composition is
briefly discussed.Comment: Accepted for publication by PR
Operations of and Future Plans for the Pierre Auger Observatory
Technical reports on operations and features of the Pierre Auger Observatory,
including ongoing and planned enhancements and the status of the future
northern hemisphere portion of the Observatory. Contributions to the 31st
International Cosmic Ray Conference, Lodz, Poland, July 2009.Comment: Contributions to the 31st ICRC, Lodz, Poland, July 200
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