1,129 research outputs found
Backbending in 50Cr
The collective yrast band and the high spin states of the nucleus 50Cr are
studied using the spherical shell model and the HFB method. The two
descriptions lead to nearly the same values for the relevant observables. A
first backbending is predicted at I=10\hbar corresponding to a collective to
non-collective transition. At I=16\hbar a second backbending occurs, associated
to a configuration change that can also be interpreted as an spherical to
triaxial transition.Comment: ReVTeX v 3.0 epsf.sty, 5 pages, 5 figures included. Full Postscript
version available at http://www.ft.uam.es/~gabriel/Cr50art.ps.g
Clonagem de fragmentos de DNA de um baculovirus patogênico à lagarta-do-álamo.
bitstream/CENARGEN/29529/1/bp205.pd
Environmental impacts of selective laser melting: do printer, powder, or power dominate?
This life cycle assessment measured environmental impacts of selective laser melting, to determine where most impacts arise: machine and supporting hardware; aluminum powder material used; or electricity used to print. Machine impacts and aluminum powder impacts were calculated by generating life cycle inventories of materials and processing; electricity use was measured by in-line power meter; transport and disposal were also assessed. Impacts were calculated as energy use (megajoules; MJ), ReCiPe Europe Midpoint H, and ReCiPe Europe Endpoint H/A. Previous research has shown that the efficiency of additive manufacturing depends on machine operation patterns; thus, scenarios were demarcated through notation listing different configurations of machine utilization, system idling, and postbuild part removal. Results showed that electricity use during printing was the dominant impact per part for nearly all scenarios, both in MJ and ReCiPe Endpoint H/A. However, some low-utilization scenarios caused printer embodied impacts to dominate these metrics, and some ReCiPe Midpoint H categories were always dominated by other sources. For printer operators, results indicate that maximizing capacity utilization can reduce impacts per part by a factor of 14 to 18, whereas avoiding electron discharge machining part removal can reduce impacts per part by 25% to 28%. For system designers, results indicate that reductions in energy consumption, both in the printer and auxiliary equipment, could significantly reduce the environmental burden of the process
r-PROCESS CALCULATIONS WITH A MICROSCOPIC DESCRIPTION OF THE FISSION PROCESS
We computed the fission properties of nuclei in the range of 84 ≤
Z ≤ 120 and 118 ≤ N ≤ 250 using the Barcelona–Catania–Paris–Madrid
(BCPM) Energy Density Functional (EDF). For the first time, a set of
spontaneous and neutron-induced fission rates were obtained from a microscopic calculation of nuclear collective inertias. These fission rates were
used as a nuclear input in the estimation of nucleosynthesis yields on neutron star mergers. We founded that the increased stability against the
fission process predicted by the BCPM allows the formation of nuclei up
to A = 286. This constitutes a first step in a systematic exploration of
different sets of fission rates on r-process abundance predictionsS.A.G., G.M.P. and M.-R.W. acknowledge support from the Helmholtz
Association through the Nuclear Astrophysics Virtual Institute (VH-VI417), and the BMBF-Verbundforschungsprojekt number 05P15RDFN1.
M.-R.W. acknowledges support from the Villum Foundation (Project No.
13164) and the Danish National Research Foundation (DNRF91). The work
of L.M.R. was supported in part by the Spanish Ministerio de EconomĂa y
Competitividad (MINECO), under contracts Nos. FIS2012-34479, FPA2015-
65929, FIS2015-63770 and by the Consolider-Ingenio 2010 Program MULTIDAR
Susceptibilidad "in vitro" de dermatofitos frente a Griseofulvina y Tolnaftato de sodio
Se ha informado acerca de una evolución de la susceptibilidad de Griseofulvina frente a Dermatofitos.Por otra parte, desconociendo el comportamiento de las cepas de estos hongos aislados en nuestro medio, como también frente al Tolnaftato de Sodio se estudian las C.I.M de estas drogas por el Método de Chmel Louria.Se comparan estos dos antifúngicos, ya que muchas veces se utilizan como un tratamiento combinado. El 97,5% de las cepas estudiadas fue sensible a una concentración igual o inferior a 1,0 microgramos por ml. de Griseofulvina y el 96,6% a 0,16 microgramos por ml. de Tolnaftato de Sodio.El 97,5% de las cepas estudiadas fue sensible a una concentración igual o inferior a 10 microgramos de Griseofulvina y el 96,6% lo es frente a 0,16 microgramos o menos de Tolnaftato de Sodio
Neutrino spectra evolution during proto-neutron star deleptonization
The neutrino-driven wind, which occurs after the onset of a core-collapse
supernova explosion, has long been considered as the possible site for the
synthesis of heavy r-process elements in the Universe. Only recently, it has
been possible to simulate supernova explosions up to ~10 seconds, based on
three-flavor Boltzmann neutrino transport. These simulations show that the
neutrino luminosities and spectra of all flavors are very similar and their
difference even decreases during the deleptonization of the proto-neutron star.
As a consequence, the ejecta are always proton rich which rules out the
possible production of heavy r-process elements (Z>56). We perform a detailed
analysis of the different weak processes that determine the neutrino spectra.
Non-electron flavor (anti)neutrinos are produced and interact only via
neutral-current processes, while electron (anti)neutrinos have additional
contributions from charge-current processes. The latter are dominated by ve
absorption on neutrons and anti-ve absorption on protons. At early times,
charge-current processes are responsible for spectral differences between.
However, as the region of neutrino decoupling moves to higher densities during
deleptonization, charge-current reactions are suppressed by final state
Pauli-blocking. anti-ve absorption on protons is suppressed due to the
continuously increasing chemical potential of the neutrons. ve absorption on
neutrons is blocked by the increasing degeneracy of the electrons. These
effects result in negligible contributions from charge-current reactions on
timescales on the order of tens of seconds, depending on the progenitor star.
Hence, the neutrino spectra are mainly determined from neutral-current
processes which do not distinguish between the different flavors and results in
the convergence of the spectra. These findings are independent of the
charge-current reaction rates used...Comment: 18 pages, 10 figures, 1 table, submitted to PR
Intrinsic vs. laboratory frame description of the deformed nucleus 48Cr
The collective yrast band of the nucleus Cr is studied using the
spherical shell model and the HFB method. Both approaches produce basically the
same axially symmetric intrinsic state up to the - accurately reproduced -
observed backbending. Agreement between both calculations extends to most
observables. The only significant discrepancy comes from the static moments of
inertia and can be attributed to the need of a more refined treatment of
pairing correlations in the HFB calculation.Comment: 4 pages, RevTeX 3.0 using psfig, 6 Postscript figures included using
uufile
Spatially inhomogeneous condensate in asymmetric nuclear matter
We study the isospin singlet pairing in asymmetric nuclear matter with
nonzero total momentum of the condensate Cooper pairs. The quasiparticle
excitation spectrum is fourfold split compared to the usual BCS spectrum of the
symmetric, homogeneous matter. A twofold splitting of the spectrum into
separate branches is due to the finite momentum of the condensate, the isospin
asymmetry, or the finite quasiparticle lifetime. The coupling of the isospin
singlet and triplet paired states leads to further twofold splitting of each of
these branches. We solve the gap equation numerically in the isospin singlet
channel in the case where the pairing in the isospin triplet channel is
neglected and find nontrivial solutions with finite total momentum of the
pairs. The corresponding phase assumes a periodic spatial structure which
carries a isospin density wave at constant total number of particles. The phase
transition from the BCS to the inhomogeneous superconducting phase is found to
be first order and occurs when the density asymmetry is increased above 0.25.
The transition from the inhomogeneous superconducting to the unpaired normal
state is second order. The maximal values of the critical total momentum (in
units of the Fermi momentum) and the critical density asymmetry at which
condensate disappears are and . The possible
spatial forms of the ground state of the inhomogeneous superconducting phase
are briefly discussed.Comment: 13 pages, including 3 figues, uses RevTeX; minor corrections, PRC in
pres
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