146 research outputs found
Unified ab initio approach to bound and unbound states: no-core shell model with continuum and its application to 7He
We introduce a unified approach to nuclear bound and continuum states based
on the coupling of the no-core shell model (NCSM), a bound-state technique,
with the no-core shell model/resonating group method (NCSM/RGM), a nuclear
scattering technique. This new ab initio method, no-core shell model with
continuum (NCSMC), leads to convergence properties superior to either NCSM or
NCSM/RGM while providing a balanced approach to different classes of states. In
the NCSMC, the ansatz for the many-nucleon wave function includes: i) a
square-integrable A-nucleon component expanded in a complete harmonic
oscillator basis; ii) a binary-cluster component with asymptotic boundary
conditions that can properly describe weakly-bound states, resonances and
scattering; and, in principle, iii) a three-cluster component suitable for the
description of, e.g., Borromean halo nuclei and reactions with final three-body
states. The Schroedinger equation is transformed into a system of
coupled-channel integral-differential equations that we solve using a modified
microscopic R-matrix formalism within a Lagrange mesh basis. We demonstrate the
usefulness of the approach by investigating the unbound 7He nucleus.Comment: 16 pages, 10 figure
Ab initio description of the exotic unbound 7He nucleus
The neutron rich exotic unbound 7He nucleus has been the subject of many
experimental investigations. While the ground-state 3/2- resonance is well
established, there is a controversy concerning the excited 1/2- resonance
reported in some experiments as low-lying and narrow (E_R ~ 1 MeV, Gamma < 1
MeV) while in others as very broad and located at a higher energy. This issue
cannot be addressed by ab initio theoretical calculations based on traditional
bound-state methods. We introduce a new unified approach to nuclear bound and
continuum states based on the coupling of the no-core shell model, a
bound-state technique, with the no-core shell model/resonating group method, a
nuclear scattering technique. Our calculations describe the ground-state
resonance in agreement with experiment and, at the same time, predict a broad
1/2- resonance above 2 MeV.Comment: 5 pages, 3 figure
Partial-wave contributions to pairing in nuclei
We present a detailed study of partial-wave contributions of nuclear forces
to pairing in nuclei. For T=1, J=0 pairing, partial waves beyond the standard
1S0 channel play an interesting role for the pair formation in nuclei. The
additional contributions are dominated by the repulsive 3P1 partial wave. Their
effects, and generally spin-triplet nuclear forces between paired nucleons, are
influenced by the interplay of spin-orbit partners. We explore the impact of
including partial waves beyond the 1S0 channel on neutron-neutron pairing gaps
in semi-magic isotopic chains. In addition, we show that nuclear forces favor
T=1, J=0 over T=0, J=1 pairing, except in low-j orbitals. This is in contrast
to the free-space motivation that suggests the formation of deuteron-like T=0
pairs in N=Z nuclei. The suppression of T=0 pairing is because the 3S1 strength
is distributed on spin-orbit partners and because of the effects of the
repulsive 1P1 channel and of D waves.Comment: 10 pages, 16 figure
Beyond-mean-field study of the possible "bubble" structure of 34Si
Recent self-consistent mean-field calculations predict a substantial
depletion of the proton density in the interior of 34Si. In the present study,
we investigate how correlations beyond the mean field modify this finding. The
framework of the calculation is a particle-number and angular-momentum
projected Generator Coordinate Method based on
Hartree-Fock-Bogoliubov+Lipkin-Nogami states with axial quadrupole deformation.
The parametrization SLy4 of the Skyrme energy density functional is used
together with a density-dependent pairing energy functional. For the first
time, the generator coordinate method is applied to the calculation of charge
and transition densities. The impact of pairing correlations, symmetry
restorations and shape mixing on the density profile is analyzed step by step.
All these effects significantly alter the radial density profile, and tend to
bring it closer to a Fermi-type density distribution.Comment: 9 pages, 7 figure
Relationship between adipose tissue dysfunction, Vitamin D deficiency and the pathogenesis of non-alcoholic fatty liver disease
Non-alcoholic fatty liver disease ( NAFLD) is the most common chronic liver disease worldwide. Its pathogenesis is complex and not yet fully understood. Over the years many studies have proposed various pathophysiological hypotheses, among which the currently most widely accepted is the "multiple parallel hits" theory. According to this model, lipid accumulation in the hepatocytes and insulin resistance increase the vulnerability of the liver to many factors that act in a coordinated and cooperative manner to promote hepatic injury, inflammation and fibrosis. Among these factors, adipose tissue dysfunction and subsequent chronic low grade inflammation play a crucial role. Recent studies have shown that vitamin D exerts an immune-regulating action on adipose tissue, and the growing wealth of epidemiological data is demonstrating that hypovitaminosis D is associated with both obesity and NAFLD. Furthermore, given the strong association between these conditions, current findings suggest that vitamin D may be involved in the relationship between adipose tissue dysfunction and NAFLD. The purpose of this review is to provide an overview of recent advances in the pathogenesis of NAFLD in relation to adipose tissue dysfunction, and in the pathophysiology linking vitamin D deficiency with NAFLD and adiposity, together with an overview of the evidence available on the clinical utility of vitamin D supplementation in cases of NAFLD
On the superfluid properties of the inner crust of neutron stars
We investigated the superfluid properties of the inner crust of neutron
stars, solving the Hartree-Fock-Bogoliubov equations in spherical Wigner-Seitz
cells. Using realistic two-body interactions in the pairing channel, we studied
in detail the Cooper-pair and the pairing-field spatial properties, together
with the effect of the proton clusters on the neutron pairing gap. Calculations
with effective pairing interactions are also presented, showing significant
discrepancies with the results obtained with realistic pairing forces. At
variance with recent studies on finite nuclei, the neutron coherence length is
found to depend on the strength of the pairing interaction, even inside the
nucleus. We also show that the Wigner-Seitz approximation breaks down in the
innermost regions of the inner crust, already at baryonic densities g cm.Comment: 11 pages, 11 figure
Insumos alternativos para produção orgânica de mudas de hortaliçasAlternative inputs for organic production of vegetable seedlings
Na cadeia produtiva de produção de mudas de hortaliças, a definição de substratos de baixo custo, que sejam facilmente disponível regionalmente e com reduzido impacto ambiental, é uma demanda atual. No projeto em questão, avaliou-se o desenvolvimento de mudas de tomate (Lycopersicon esculentum L.) produzidas em estufa plástica do tipo túnel baixo, no período de 03/09/2014 a 21/10/2014, na Universidade Estadual do Rio Grande do Sul, unidade de Santana do Livramento. Os tratamentos foram constituídos de diferentes formulações de substratos com base em casca de arroz, sendo: 1 - casca de arroz carbonizada (100%); 2 - composto orgânico comercial (100%); 3 - casca de arroz carbonizada (33%) + esterco bovino (33%) + solo (33%); 4 - casca de arroz carbonizada (33%) + esterco equino ( 33%) + solo (33%). As variáveis agronômicas medidas foram precocidade de emergência de plântulas, altura de mudas, número de folhas, matéria seca da parte aérea, sendo que todas apontaram para um resultado superior ao utilizar o substrato casca de arroz carbonizada (33%) + esterco bovino (33%) + solo (33%). Nesse sentido, conclui-se que se pode recomendar ao agricultor familiar essa opção para utilizar no meio de cultivo de mudas na propriedade rural, já que existe a facilidade de obtenção dos materiais, aliada à redução dos custos de produção e adequado desempenho.AbstractIn the productive chain of vegetables seedings growth, the definition of low cost substracts wich are easily available in the local area and with reduced environment damage is current demand. This present project the development of tomatoes seedings (Lycopersicon esculentum L),produced inside hatchery with plastic cover and short tunnel model,in the period from 03/09/2014 to 21/10/2014 at Rio Grande do Sul State University, Santana do Livramento Unit. The processings were made in different substracts formulations based on rice rusk,were: 1-carbonized rice rusk(100%);2-comercial organic compost(100%); 3-carbonized rice rusk(33%)+cattle manure(33%)+soil (33%);4-carbonized rice rusk(33%)+horse manure(33%)+soil(33%) The agronomic variables measures were emergency precocity of seedlings, seedings height, number of leaves, dry material of the air part, and all of them showed the best result with the substract of carbonized rice rusk (33%)+cattle manure (33%)+soil(33%). So we conclude that we can recommend this option to the farmer, to use that in the cultivation of seedings, as well as the facility of getting the materials, the reduction of production costs and an appropriate performance
GPR and seismic surveying in the World War I scenario of Punta Linke (Ortles-Cevedale Group, Italian Alps).
The Ortles-Cevedale Group was the setting of repeated clashes occurring under extreme conditions and at the highest altitudes of all fightings in the Great War (WWI). The research scenario associated with the group is very challenging because modern research faces a series of logistical and climatic obstacles. The gradual retreat of glaciers has unearthed several archaeological remains of WWI such as barracks, barbed wire, military ammunition, weapons and other materials. The study site is the saddle between M. Vioz and Punta Linke, where the Historic War Museum of Pejo, under the direction of the Archaeological Service of the Province of Trento (Soprintendenza per i Beni Culturali, Ufficio Beni Archeologici), started an archaeological excavation in the year 2009 of some of the infrastructure of the cableway station, which also includes a tunnel section in the bedrock.
The saddle is placed at the head of Forni Glacier. GPR and seismic imaging was the best survey choice to characterize the glaciological and geo-archaeological context and to find structures or remains within the ice mass. Geophysical imaging spanned two campaigns in the years 2010 and 2011. The ice-rock interface was reconstructed in detail to depths greater than 45-50 m. The surface of the bedrock reveals a complex morphology, with several undulations and two rocky ridges elongated in the NNW-SSE direction. They identified some anomalous reflectors within the ice mass located near the western edge of the saddle of Punta Linke. The interpretation of radar profiles seems to indicate the presence of a tunnel in the ice, whose geometry and position is similar to others excavated in alpine glaciers during the Great War
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