4,833 research outputs found
Realistic shell model and nuclei around 132Sn
This contribution reports on a shell-model study of nuclei in the 132Sn region employing a realistic effective interaction derived from the CD-Bonn nucleon-nucleon potential renormalized through the use of the Vlow−k approach. We shall focus on some selected results for nuclei with a few valence particles and/or holes with respect to 132Sn, namely Sn isotopes with N > 82 and 130Te, which have, in part, been discussed in previous papers. Results are compared with experiments, and predictions that may provide guidance to future experiments are also discussed. It is the aim of this contribution to underline the importance of studying 132Sn neighbours to acquire a deep understanding of nuclear structure, that may be very useful also in other physics fields, and to show that the realistic shell model is a very effective tool to conduct these studies
A quasi-static nonlinear analysis for assessing the fire resistance of 3d frames exploiting time-dependent yield surface
In this work an automatic procedure for evaluating the axial force-biaxial bending yield surface of reinforced concrete sections in fire is proposed. It provides an accurate time-dependent expression of the yield condition by a section analysis carried out once and for all, accounting for the strength reduction of the materials, which is a function of the fire duration. The equilibrium state of 3D frames with such yield conditions, once discretized using beam finite elements, is formulated as a nonlinear vectorial equation defining a curve in the hyperspace of the discrete variables and the fire duration. A generalized path-following strategy is proposed for tracing this curve and evaluating, if it exists, the limit fire duration, that is the time of exposure which leads to structural collapse. Compared to the previous proposals on the topic, which are limited to local sectional checks, this work is the first to present a global analysis for assessing the fire resistance of 3D frames, providing a time history of the fire event and taking account of the stress redistribution. Numerical examples are given to illustrate and validate the proposal
Removal of the center of mass in nuclei and its effects on 4He
Abstract The singular value decomposition of rectangular matrices is shown to provide the recipe for removing the center of mass spurious admixtures from the multiphonon basis generated by an equation of motion method for solving the nuclear eigenvalue problem. It works for any single particle basis without any energy restriction on the selection of the configurations. Its effects on 4He are illustrated
La teoría general del derecho en el marxismo
En el marxismo no existe fundamento para una concepción
personalista del orden social y político, que respeten la dignidad
de la persona humana, entendida como ente dinámico que
tiende a la realización de cada individuo mediante la consecución
de su fin personal. Más bien, el sistema marxista es
transpersonalista: el individuo es considerado no como un todo
con un fin personal, sino como medio para la realización de
otros fines, medio para la realización de la humanidad, de la
cual es pura parte. El filósofo comunista polaco, A. Schaff,
reconoce paladinamente este principio: «Para el marxismo, (el
hombre) en cuanto parte específica de la naturaleza animada,
es un producto de la sociedad, y, en este sentido, es la totalidad
de las relaciones sociales... Esto no tiene nada común con la existencia autónoma del individuo, tal como lo sostiene el personalismo
o existencialismo»90. La persona no tiene una realidad
propia, no es un ente per se stans; por ello, no tiene fin último
propio. El ser humano es un producto social y, como tal, engarzado
en el proceso, del cual es parte.
A la teoría jurídica de Marx, tomada aisladamente y en abstracto,
no se puede llamar positivista. Pero hay que tener en
cuenta que Marx nunca tuvo el poder en sus manos, fue un puro
teórico. Si Marx hubiera tenido la oportunidad de coger las riendas
del gobierno, ¿qué sistema jurídico hubiera impuesto? Naturalmente
estamos aquí en el terreno de las puras conjeturas. Pero en
el espíritu de Marx existen gérmenes que permiten suponer la utilización
de un sistema positivista, adaptado a los fines de la revolución.
Personalmente, Marx era un volcán de odio contra sus
enemigos, especialmente contra el sistema capitalista. En segundo
lugar, él se definía a sí mismo como un revolucionario. Así lo
afirmó también Engels en su discurso fúnebre: «El vio en la ciencia
una gran palanca, una fuerza revolucionaria en el sentido más
verdadero de la palabra... Porque Marx fue realmente un revolucionario
como él se llamaba a sí mismo»9 1. En la teoría marxista,
el modo de producción cambia en virtud del continuo progreso de
las fuerzas productivas. Pero, en realidad, todos los líderes
comunistas y de revoluciones postergan el derecho y lo reducen a
un simple medio para el logro de sus fines. Esto nos hace suponer
que en el espíritu marxista estaban presentes los gérmenes del
positivismo, que no pudieron desarrollar porque no alcanzó el
poder, como Lenin.
Por tanto, la concepción marxista del derecho es esencialmente
revolucionaria y, en la praxis, el torrente de la revolución
inspira el positivismo e incluso el nihilismo. El derecho es medio
y, por ello, cambia en la medida reclamada por las decisiones de
sus líderes, que se erigen en fuente de toda norma y rechazan toda
normatividad superior a su voluntad. Así nace el puro decisionismo
como locomotora de la revolución y de la historia. El lider revolucionario,
elevado a la categoría de ser supremo, rechaza toda
norma, todo orden jurídico, superior a sus decisiones
On random flights with non-uniformly distributed directions
This paper deals with a new class of random flights defined in the real space characterized
by non-uniform probability distributions on the multidimensional sphere. These
random motions differ from similar models appeared in literature which take
directions according to the uniform law. The family of angular probability
distributions introduced in this paper depends on a parameter which
gives the level of drift of the motion. Furthermore, we assume that the number
of changes of direction performed by the random flight is fixed. The time
lengths between two consecutive changes of orientation have joint probability
distribution given by a Dirichlet density function.
The analysis of is not an easy task, because it
involves the calculation of integrals which are not always solvable. Therefore,
we analyze the random flight obtained as
projection onto the lower spaces of the original random
motion in . Then we get the probability distribution of
Although, in its general framework, the analysis of is very complicated, for some values of , we can provide
some results on the process. Indeed, for , we obtain the characteristic
function of the random flight moving in . Furthermore, by
inverting the characteristic function, we are able to give the analytic form
(up to some constants) of the probability distribution of Comment: 28 pages, 3 figure
An Experimental-Numerical Investigation of the Wake Structure of a Hovering Rotor by PIV Combined with a Γ2 Vortex Detection Criterion
The rotor wake aerodynamic characterization is a fundamental aspect for the development
and optimization of future rotary-wing aircraft. The paper is aimed at experimentally and
numerically characterizing the blade tip vortices of a small-scale four-bladed isolated rotor in hover
conditions. The investigation of the vortex decay process during the downstream convection of
the wake is addressed. Two-component PIV measurements were carried out below the rotor disk
down to a distance of one rotor radius. The numerical simulations were aimed at assessing the
modelling capabilities and the accuracy of a free-wake Boundary Element Methodology (BEM). The
experimental and numerical results were investigated by the G2 criterion to detect the vortex location.
The rotor wake mean velocity field and the instantaneous vortex characteristics were investigated.
The experimental/numerical comparisons show a reasonable agreement in the estimation of the
mean velocity inside the rotor wake, whereas the BEM predictions underestimate the diffusion effects.
The numerical simulations provide a clear picture of the filament vortex trajectory interested in
complex interactions starting at about a distance of z/R = 0.5. The time evolution of the tip vortices
was investigated in terms of net circulation and swirl velocity. The PIV tip vortex characteristics
show a linear mild decay up to the region interested by vortex pairing and coalescence, where a
sudden decrease, characterised by a large data scattering, occurs. The numerical modelling predicts
a hyperbolic decay of the swirl velocity down to z/R = 0.4 followed by an almost constant decay.
Instead, the calculated net circulation shows a gradual decrease throughout the whole wake development.
The comparisons show discrepancies in the region immediately downstream the rotor disk but
significant similarities beyond z/R = 0.5
Cantharellus lilacinopruinatus Hermitte, Eyssart. & Poumarat, a Catalunya i les Illes Balears
Es descriu , comenta i il·lustra un interessant t áxon de les CantharelI ácies: Cantharellus
Iilacinopruinatus Hermitte, Eyssart. & Poumarat, recol·lectat per primer cop a Catalunya i Illes
Balears.An interesting taxon of Cantharellaceae: Cantharellus lilacinop ruinatu s Hennitte,
Eyssart. & Poumarat, previou sly unrecorded in Catalonia and the Balearic Island s, is described,
commented and illustrated.Se describe, comenta e ilustra un interesante taxón de las Cantareláceas: Cantharellus
lilacinopruinatus Hennitte, Eyssart. & Poumarat, recolectado por primera vez en Cataluña y Baleares
Empirical vulnerability curves for Italian mansory buildings: evolution of vulnerability model from the DPM to curves as a function of accelertion
In the framework of the emergency management in the case of seismic events, the evaluation of the expected damage represents a basic requirement for risk informed planning. Seismic risk is defined by the probability to reach a level of damage on given exposed elements caused by seismic events occurring in a fixed period and in a fixed area. To this purpose, the expected seismic input, the exposed elements and their vulnerability have to be correctly evaluated. The aim of the research is to define a correct model of vulnerability curves, in PGA, for masonry structures in Italy, by heuristic approach starting from damage probability matrices (DPMs). To this purpose, the PLINIVS database, containing data on major Italian seismic events, has been used and supported by “critical” assumption on missing data. To support the reliability of this assumption, two vulnerability models, considering or not the hypothesis on the missing data, have been estimated and used to calculate the seismic scenario of the L’Aquila 2009 earthquake through the IRMA (Italian Risk MAp) platform. Finally, a comparison between the outcomes elaborated by IRMA platform and the observed damage collected in the AEDES forms, has been done. © 2020, The Author(s)
Dense gas and exciting sources of the molecular outflow in the AFGL 437 star-forming region
We present Very Large Array (VLA) high resolution observations of the
NH3(1,1) and NH3(2,2) molecular transitions towards the high mass star forming
region AFGL 437. Our aim was to investigate if the poorly collimated CO
molecular outflow previously detected in the region is the result of a
projection effect, with no intrinsic bipolarity, as suggested by Gomez et al.
We complemented our observations with radio continuum archived data from the
VLA at 2 and 3.6 cm, and with unpublished public data at 450 {\mu}m taken with
Submillimetre Common-User Bolometer Array at the James Clerk Maxwell Telescope.
Ammonia emission was found mainly in three clumps located at the south and east
of the position of the compact infrared cluster of AFGL 437, where the CO
outflow seemed to have its origin. One of the NH3(1,1) clumps coincides with
the maximum of NH3(2,2) and with a local peak of emission at 450 {\mu}m. A near
infrared source (s11) is also found at that position. Our continuum map at 2 cm
shows extended elongated emission associated with the infrared source AFGL
437W. This elongated morphology and its spectral index between 3.6 and 2 cm
(\simeq 0.4) suggest the presence of a jet in AFGL 437W. We suggest that
several molecular bipolar outflows may exist in the region. The observed CO
outflow would be the superposition of those individual outflows, which would
explain its low degree of collimation observed at larger scales.Comment: 9 pages, 5 figures, 3 tables, accepted by MNRA
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