1,674 research outputs found
Conservation Laws in Smooth Particle Hydrodynamics: the DEVA Code
We describe DEVA, a multistep AP3M-like-SPH code particularly designed to
study galaxy formation and evolution in connection with the global cosmological
model. This code uses a formulation of SPH equations which ensures both energy
and entropy conservation by including the so-called \bn h terms. Particular
attention has also been paid to angular momentum conservation and to the
accuracy of our code. We find that, in order to avoid unphysical solutions, our
code requires that cooling processes must be implemented in a non-multistep
way.
We detail various cosmological simulations which have been performed to test
our code and also to study the influence of the \bn h terms. Our results
indicate that such correction terms have a non-negligible effect on some
cosmological simulations, especially on high density regions associated either
to shock fronts or central cores of collapsed objects. Moreover, they suggest
that codes paying a particular attention to the implementation of conservation
laws of physics at the scales of interest, can attain good accuracy levels in
conservation laws with limited computational resources.Comment: 36 pages, 10 figures. Accepted for publication in The Astrophysical
Journa
Meta-stereotypes among women living homeless: Content, uniformity, and differences based on gender in Madrid, Spain
This paper examines the content and degree of uniformity of meta-stereotypes among women living homeless in Madrid, Spain, and the differences with their male counterparts. The study was conducted utilizing a structured interview with a representative sample of men living homeless (n=158) and a convenience sample of a similar size (n=138) of women living homeless. The results show that the meta?stereotypes of women living homeless in Madrid are characterized by mainly negative (e.g., consumers of alcohol, drug users, lazy, criminals) or indulgent (e.g., physically and psychologically worn out, rejected by society, sick) contents, with very limited positive (e.g., courteous, respectful, polite) contents, and a high degree of uniformity. There are no major differences in the content of meta?stereotypes of the female interviewees in terms of their age, academic background, motherhood, or nationality. Compared to men in the same situation, a larger percentage of women living homeless agree with negative and indulgent meta-stereotypes, and a smaller percentage agree with positive meta-stereotypes.Ministerio de Economía, Industria y Competitivida
Caracterización mecánica de pistas deportivas fabricadas con materiales procedentes de neumáticos fuera de uso (NFU)
Congreso celebrado en la Escuela de Arquitectura de la Universidad de Sevilla desde el 24 hasta el 26 de junio de 2015.The European Framework Directive 2008/98/EC on waste established as priority reuse and recycling before other recovery alternatives. In this normative reference, one the main waste flows identified are the end-of-life tyres, as a material whose mechanical properties could provide advantage in the construction of new structures. This paper presents the mechanical characterization of a layer made with shredded tires out of use, inside a section of a sportive track which included a sand layer. The use of the shredded tires out of use provides special features related with elasticity and damping to the sportive surface. In order to do that, a new test based on UNE-14809 was designed. A number of tests were performed using different configuration of sand and shredded tires. From the results obtained, a numerical model was implemented in FEA software
Biomimetic Ca-P coatings Incorporating bisphosphonates produced on starch-based degradable biomaterials
In this study, sodium clodronate, a well-known therapeutic agent from the family
of bisphosphonates (BPs), is incorporated in a biomimetic calcium phosphate (CaP) coating,
previously formed on the surface of a starch-based biomaterial by a sodium silicate
methodology, as a strategy to develop a site-specific drug delivery system for bone tissue
regeneration applications. The effects on the resulting CaP coatings were evaluated in terms of
morphology, chemistry, and structure. The dissolution of Ca and P from the coating and the
release profiles of sodium clodronate was also assessed. As a preliminary approach, this first
study also aimed at evaluating the effects of this BP on the viability of a human osteoblastic
cell line since there is still little information available on the interaction between BPs and this
type of cells. Sodium clodronate was successfully incorporated, at different doses, in the
structure of a biomimetic CaP layer previously formed by a sodium silicate process. This
type of BPs had a stimulatory effect on osteoblastic activity, particularly at the specific
concentration of 0.32 mg/mL. It is foreseen that these coatings can, for instances, be
produced on the surface of degradable polymers and then used for regulating the
equilibrium on osteoblastic/osteoclastic activity, leading to a controlled regenerative effect
at the interface between the biomaterial and bone
Unifying thermodynamic and kinetic descriptions of single-molecule processes: RNA unfolding under tension
We use mesoscopic non-equilibrium thermodynamics theory to describe RNA
unfolding under tension. The theory introduces reaction coordinates,
characterizing a continuum of states for each bond in the molecule. The
unfolding considered is so slow that one can assume local equilibrium in the
space of the reaction coordinates. In the quasi-stationary limit of high
sequential barriers, our theory yields the master equation of a recently
proposed sequential-step model. Non-linear switching kinetics is found between
open and closed states. Our theory unifies the thermodynamic and kinetic
descriptions and offers a systematic procedure to characterize the dynamics of
the unfolding processComment: 13 pages, 3 figure
Microhardness of starch based biomaterials in simulated physiological conditions
In this work the variation of the surface mechanical properties of starch-based biomaterials with immersion time was followed using
microhardness measurements. Two blends with very distinct water uptake capabilities, starch/cellulose acetate (SCA) and starch/poly-
(e-caprolactone) (SPCL), were immersed in a phosphate buffer solution (PBS) at 37.5 C for various times. The microhardness of the
blends decreased significantly ( 50% for SPCL and 94% for SCA), within a time period of 30 days of immersion, reflecting the different
hydrophilic character of the synthetic components of the blends. The dependence of microhardness on the applied loading time and load
was also analysed and showed a power law dependency for SCA. Water uptake and weight loss measurements were performed for the
same immersion times used in the microhardness experiments. The different swelling/degradation behaviour presented by the blends was
related to the respective variation in microhardness. Moreover, complementary characterization of the mechanical properties of SCA
and SPCL was accomplished by dynamic mechanical analysis (DMA) and creep measurements. Microhardness measurements proved
to be a useful technique for characterizing the mechanical behaviour near the surface of polymeric biomaterials, including in simulated
physiological conditions
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