704 research outputs found
Few body Calculation of Neutrino Neutral Inelastic scattering on 4He
The inelastic neutral reaction of neutrino on 4He is calculated using two
modern nucleon--nucleon potentials. Full final state interaction among the four
nucleons is considered, via the Lorentz integral transform (LIT) method. The
effective interaction hyperspherical-harmonic (EIHH) approach is used to solve
the resulting Schrodinger like equations. A detailed energy dependent
calculation is given in the impulse approximation.Comment: 4 pages; talk at 18th International Conference on Few-Body Problems
in Physics (FB18), Santos, SP, Brazil, August 200
Securitized volunteerism and neo-nationalism in Israel’s rural periphery
Contemporary volunteering is often considered a neoliberal phenomenon that has become prevalent in an era of post-national sentiments and individualism. Although it is frequently depicted as non-political, it may serve the promotion of political agendas, such as neo-nationalism, outside the traditional frame of the state and its institutions. This becomes particularly salient when non-governmental organizations practice volunteering in ways that undermine the state’s monopoly in the realms of security and public order. We conceptualize this tendency as securitized volunteering – instances of volunteering work that is promoted by, in this case non-state, organizations who are involved in voluntary security activities that are violent (or potentially violent). Drawing on an ethnographic study of the Israeli organization HaShomer HaChadash (The New Guard), this article demonstrates how agricultural and security volunteering is used to advance a neo-nationalist agenda that circumvents the state, and at the same time maintains an apolitical stance. This is achieved through the implementation of two corresponding forms of securitized volunteering – civilianization of security volunteerism and securitization of civilian volunteerism. Blurring the distinction between both forms enables the organization to attract supporters and volunteers that come from various social sectors and to reinforce its seemingly apolitical position and nationalist agenda
Neutrino Breakup of A=3 Nuclei in Supernovae
We extend the virial equation of state to include 3H and 3He nuclei, and
predict significant mass-three fractions near the neutrinosphere in supernovae.
While alpha particles are often more abundant, we demonstrate that energy
transfer cross-sections for muon and tau neutrinos at low densities are
dominated by breakup of the loosely-bound 3H and 3He nuclei. The virial
coefficients involving A=3 nuclei are calculated directly from the
corresponding nucleon-3H and nucleon-3He scattering phase shifts. For the
neutral-current inelastic cross-sections and the energy transfer cross
sections, we perform ab-initio calculations based on microscopic two- and
three-nucleon interactions and meson-exchange currents.Comment: 6 pages, 2 figures, minor additions, to appear in Phys. Rev.
Photonuclear sum rules and the tetrahedral configuration of He
Three well known photonuclear sum rules (SR), i.e. the Thomas-Reiche-Kuhn,
the bremsstrahlungs and the polarizability SR are calculated for 4He with the
realistic nucleon-nucleon potential Argonne V18 and the three-nucleon force
Urbana IX. The relation between these sum rules and the corresponding energy
weighted integrals of the cross section is discussed. Two additional
equivalences for the bremsstrahlungs SR are given, which connect it to the
proton-neutron and neutron-neutron distances. Using them, together with our
result for the bremsstrahlungs SR, we find a deviation from the tetrahedral
symmetry of the spatial configuration of 4He. The possibility to access this
deviation experimentally is discussed.Comment: 13 pages, 1 tabl
Introduction to the Armed Forces & Society forum on military reserves in the “New Wars”
This is the final version. Available on open access from SAGE Publications via the DOI in this record. This Armed Forces & Society forum is dedicated to exploring recent trends in the characteristics of military reserves and of the changing character of reserve forces within the armed forces within the military, the civilian sphere, and in between them. To bring new and critical perspectives to the study of reserve forces and civil–military relations, this introduction and the five articles that follow draw on two organizing conceptual models: The first portrays reservists as transmigrants and focuses on the plural membership of reservists in the military and in civilian society and the “travel” between them. The second model focuses on the multiple formal and informal compacts (contracts, agreements, or pacts) between reservists and the military
Case study: calculation of a narrow resonance with the LIT method
The possibility to resolve narrow structures in reaction cross sections in
calculations with the Lorentz integral transform (LIT) method is studied. To
this end we consider a fictitious two-nucleon problem with a low-lying and
narrow resonance in the nucleon-nucleon partial wave and calculate the
corresponding ``deuteron photoabsorption cross section''. In the LIT method the
use of continuum wave functions is avoided and one works instead with a
localized function \tilde\Psi. In this case study it is investigated how far
into the asymptotic region \tilde\Psi has to be determined in order to obtain a
precise resolution of the artificially introduced E1 resonance. Comparing with
the results of a conventional calculation with explicit neutron-proton
continuum wave functions it is shown that the LIT approach leads to an
excellent reproduction of the cross section in the resonance region and of
further finer cross section details at higher energies. To this end, however,
for \tilde\Psi one has to take into account two-nucleon distances up to at
least 30 fm.Comment: 18 pages, 11 figure
Quasiparticle interaction in nuclear matter with chiral three-nucleon forces
We derive the effective interaction between two quasiparticles in symmetric
nuclear matter resulting from the leading-order chiral three-nucleon force. We
restrict our study to the L=0,1 Landau parameters of the central quasiparticle
interaction computed to first order. We find that the three-nucleon force
provides substantial repulsion in the isotropic spin- and isospin-independent
component F_0 of the interaction. This repulsion acts to stabilize nuclear
matter against isoscalar density oscillations, a feature which is absent in
calculations employing low-momentum two-nucleon interactions only. We find a
rather large uncertainty for the nuclear compression modulus due to a sensitive
dependence on the low-energy constant c_3. The effective nucleon mass on the
Fermi surface, as well as the nuclear symmetry energy, receive only small
corrections from the leading-order chiral three-body force. Both the anomalous
orbital g-factor and the Landau-Migdal parameter g'_{NN} (characterizing the
spin-isospin response of nuclear matter) decrease with the addition of
three-nucleon correlations. In fact, the anomalous orbital g-factor remains
significantly smaller than its value extracted from experimental data, whereas
g'_{NN} still compares well with empirical values. The inclusion of the
three-nucleon force results in relatively small p-wave (L=1) components of the
central quasiparticle interaction, thus suggesting an effective interaction of
short range.Comment: 20 pages, 6 figure
alpha-particle photoabsorption with a realistic nuclear force
The 4He total photoabsorption cross section is calculated with the realistic
nucleon-nucleon potential Argonne V18 and the three-nucleon force (3NF) Urbana
IX. Final state interaction is included rigorously via the Lorentz Integral
Transform method. A rather pronounced giant resonance with peak cross sections
of 3 (3.2) mb is obtained with (without) 3NF. Above 50 MeV strong 3NF effects,
up to 35%, are present. Good agreement with experiment is found close to
threshold. A comparison in the giant resonance region is inconclusive, since
present data do not show a unique picture.Comment: 13 pages, 4 figures; corrected experimental data in Fig.4b and
slightly modified discussion of Fig.4
Study of cosolvent-induced α-chymotrypsin fibrillogenesis: Does protein surface hydrophobicity trigger early stages of aggregation reaction?
The misfolding of specific proteins is often associated with their assembly into fibrillar aggregates, commonly termed amyloid fibrils. Despite the many efforts expended to characterize amyloid formation in vitro, there is no deep knowledge about the environment (in which aggregation occurs) as well as mechanism of this type of protein aggregation. Alpha-chymotrypsin was recently driven toward amyloid aggregation by the addition of intermediate concentrations of trifluoroethanol. In the present study, approaches such as turbidimetric, thermodynamic, intrinsic fluorescence and quenching studies as well as chemical modification have been successfully used to elucidate the underlying role of hydrophobic interactions (involved in early stages of amyloid formation) in α-chymotrypsin-based experimental system. © 2009 Springer Science+Business Media, LLC
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