720 research outputs found
Asteroseismology of evolved stars to constrain the internal transport of angular momentum. VI. Testing a parametric formulation for the azimuthal magneto-rotational instability
Asteroseismic measurements of the internal rotation rate in evolved stars
pointed out to a lack of angular momentum (AM) transport in stellar evolution
models. Several physical processes in addition to hydrodynamical ones were
proposed as candidates for the missing mechanism. Nonetheless, no current
candidate can satisfy all the constraints provided by asteroseismology. We
revisit the role of a candidate process whose efficiency scales with the
contrast between the rotation rate of the core and the surface which was
proposed to be related to the azimuthal magneto-rotational instability (AMRI)
by Spada et al. We compute stellar evolution models of low- and
intermediate-mass stars with the parametric formulation of AM transport
proposed by Spada et al. until the end of the core-helium burning for low- and
intermediate-mass stars and compare our results to the latest asteroseismic
constraints available in the post main sequence phase. Both hydrogen-shell
burning stars in the red giant branch and core-helium burning stars of low- and
intermediate-mass in the mass range can be simultaneously reproduced by this kind of parametrisation.
Given current constraints from asteroseismology, the core rotation rate of
post-main sequence stars seems to be well explained by a process whose
efficiency is regulated by the internal degree of differential rotation in
radiative zones.Comment: Accepted for publication in Astronomy & Astrophysics. 10 pages, 10
figures, 1 appendi
On Weierstra{\ss} semigroups at one and two points and their corresponding Poincar\'e series
The aim of this paper is to introduce and investigate the Poincar\'e series
associated with the Weierstra{\ss} semigroup of one and two rational points at
a (not necessarily irreducible) non-singular projective algebraic curve defined
over a finite field, as well as to describe their functional equations in the
case of an affine complete intersection.Comment: Beginning of Section 3 and Subsection 3.1 were modifie
Design of a 5G Multimedia Broadcast Application Function Supporting Adaptive Error Recovery
The demand for mobile multimedia streaming services has been steadily growing
in recent years. Mobile multimedia broadcasting addresses the shortage of radio
resources but introduces a network error recovery problem. Retransmitting
multimedia segments that are not correctly broadcast can cause service
disruptions and increased service latency, affecting the quality of experience
perceived by end users. With the advent of networking paradigms based on
virtualization technologies, mobile networks have been enabled with more
flexibility and agility to deploy innovative services that improve the
utilization of available network resources. This paper discusses how mobile
multimedia broadcast services can be designed to prevent service degradation by
using the computing capabilities provided by multiaccess edge computing (MEC)
platforms in the context of a 5G network architecture. An experimental platform
has been developed to evaluate the feasibility of a MEC application to provide
adaptive error recovery for multimedia broadcast services. The results of the
experiments carried out show that the proposal provides a flexible mechanism
that can be deployed at the network edge to lower the impact of transmission
errors on latency and service disruptions.Comment: 14 pages, 10 figure
Prevalence and associated factors to suicide attempts in low-income adolescents from the Caribbean region of Colombia
Objectives
to establish the prevalence and associated factors to suicide attempts (SA) in low-income adolescents from the Caribbean region of Colombia
Methods
A cross sectional study was conducted. Adolescents between 10-24 years of age residents in 21 municipalities in the Caribbean region of Colombia were randomly selected from the population affiliated to a subsidized-regime insurance company between 2014-2018. A previously constructed questionnaire was used to obtain information regarding sociodemographic variables and potential risk factors. A self-reported antecedent of suicide attempt was defined as a case. Bivariate and multivariate logistic regression models were used to establish associated factors. Absolute and relative frequencies were reported. Relative frequencies were compared with the Chi2 test and continuous variables were compared with the t-test. A p value <0.050 was considered significan
Angular momentum transport by magnetic fields in main sequence stars with Gamma Doradus pulsators
Context. Asteroseismic studies showed that cores of post main-sequence stars
rotate slower than theoretically predicted by stellar models with purely
hydrodynamical transport processes. Recent studies on main sequence stars,
particularly Gamma Doradus ( Dor) stars, revealed their internal
rotation rate for hundreds of stars, offering a counterpart on the main
sequence for studies of angular momentum transport. Aims. We investigate
whether such a disagreement between observed and predicted internal rotation
rates is present in main sequence stars by studying angular momentum transport
in Dor stars. Furthermore, we test whether models of rotating stars
with internal magnetic fields can reproduce their rotational properties.
Methods. We compute rotating models with the Geneva stellar evolution code
taking into account meridional circulation and the shear instability. We also
compute models with internal magnetic fields using a general formalism for
transport by the Tayler-Spruit dynamo. We then compare these models to
observational constraints for Dor stars that we compiled from the
literature, combining so the core rotation rates, projected rotational
velocities from spectroscopy, and constraints on their fundamental parameters.
Results. We show that combining the different observational constraints
available for Dor stars enable to clearly distinguish the different
scenarios for internal angular momentum transport. Stellar models with purely
hydrodynamical processes are in disagreement with the data whereas models with
internal magnetic fields can reproduce both core and surface constraints
simultaneously. Conclusions. Similarly to results obtained for subgiant and red
giant stars, angular momentum transport in radiative regions of Dor
stars is highly efficient, in good agreement with predictions of models with
internal magnetic fields.Comment: Accepted for publication in Astronomy & Astrophysics. 16 pages, 17
figures, 1 appendi
Metodología BIM en el grado de edificación: modelo de taller en la asignatura Expresión Gráfica de Tecnologías
The concept of BIM implies a radical change in the way of facing the architectural design and the life cycle process of the projects and the buildings. It is an efficient and open system of communication and cooperation between the different operators involved in the construction process and, therefore, it becomes in a suitable tool for its implementation in the Technical Schools of Engineering and Architecture. This paper defends the recognition of the BIM methodology as a collaborative and coordinated instrument for its application in the university teaching in degrees of this field of knowledge, so that the flow of interdisciplinary information is efficient. The experience of the implementation of this methodology in the Degree in Building is described. It is based on a workshop-integrator model in the subject called Graphic Expression of Technologies. Subsequently, educational enquiries derived from the innovation developed are collected, showing its benefits for the student body as regards learning, and also the limitations found. In conclusion, the outcomes obtained lead to continue supporting this technological integration. Finally, a series of recommendations for its improvement are provided, concerning the way to guide the students throughout the experience, and also related to the teaching organisation through the curriculum
Effects of different feeding frequencies on growth, feed utilisation, digestive enzyme activities and plasma biochemistry of gilthead sea bream (Sparus aurata) fed with different fishmeal and fish oil dietary levels
In the context of Mediterranean aquaculture little attention has been paid to
the manipulation of feeding frequency at the on-growing phase. The effects of
different feeding frequencies: one meal per day, two meals per day, three meals
per day on growth, digestive enzyme activity, feed digestibility and plasma
biochemistry were studied in gilthead sea bream (Sparus aurata, L. 1758) fed
with high and low fishmeal and fish oil levels. Isonitrogenous and isolipidic
extruded diets were fed to triplicate fish groups by a fixed ration over 109
days. No significant effects of feeding frequency on overall performance, feed
efficiency and feed digestibility during the on-growing of gilthead sea bream
fed high or low fishmeal and fish oil dietary level were observed. Pepsin
activity showed an apparent decrease in fish receiving more than one meal a day
which was not compensated by an increased production of alkaline proteases
particularly in fish fed on low FM. Although there were no effects on growth
and feed utilisation at increasing feeding frequency, trypsin decreased
significantly with an increasing number of meals only under low FMFO diet.
Thus, it seemed that consecutive meals could have amplified the potential
trypsin inhibitor effect of the vegetable meal-based diet adopted. Results of
the plasma parameters related to nutritional and physiological conditions were
not affected by feeding frequency. The higher level of plasma creatinine
detected in fish fed a single daily meal with high FMFO level seems to be
within physiological values in relation to the higher protein efficiency
observed with this diet. According to the results, gilthead sea bream seems
able to maximise feed utilisation regardless of the number of meals, and this
could be a useful indicator for planning feeding activity at farm level to
optimise growth of fish and costs of feeding procedures
Liquidity and the multiscaling properties of the volume traded on the stock market
We investigate the correlation properties of transaction data from the New
York Stock Exchange. The trading activity f(t) of each stock displays a
crossover from weaker to stronger correlations at time scales 60-390 minutes.
In both regimes, the Hurst exponent H depends logarithmically on the liquidity
of the stock, measured by the mean traded value per minute. All multiscaling
exponents tau(q) display a similar liquidity dependence, which clearly
indicates the lack of a universal form assumed by other studies. The origin of
this behavior is both the long memory in the frequency and the size of
consecutive transactions.Comment: 7 pages, 3 figures, submitted to Europhysics Letter
Interaction Between Dietary Lipid Level and Seasonal Temperature Changes in Gilthead Sea Bream Sparus aurata: Effects on Growth, Fat Deposition, Plasma Biochemistry, Digestive Enzyme Activity, and Gut Bacterial Community
A 121-day feeding trial was undertaken to test the effects of two dietary lipid levels (16 and 21% L16, L21) in triplicated gilthead sea bream groups (initial weight: 67.5 g) reared at two different water temperatures (high, H 23°C and low, L 17°C) in the same recirculation system but exposed to a switch in temperature after 58 days. Fish kept at H were transferred to L (HL transition, autumn shift), and the fish kept at L were exposed to H (LH transition, summer shift), while continuing to receive the same diet to apparent satiation in each group. At the end of the trial, no significant diet effect on specific growth rate (SGR), feed intake (FI), and feed conversion rate (FCR) were detected in fish exposed to HL transition compared with those exposed to LH transition, while gross lipid efficiency (GLE) and lipid efficiency ratio (LER) were higher in L16. After temperature changes, L16 displayed higher SGR, FI, GLE, and LER, while mesenteric fat index was reduced. After temperature changes, the combined effects of low lipid diet and low temperature conditions resulted in higher pepsin activity, while trypsin, chymotrypsin, and lipase activities were generally higher at high lipid content. The combined effect of diet and temperature did not alter the metabolic plasma profile, except for the observed final higher aspartate aminotransferase (AST) and alkaline phosphatase (ALP) values when combining high dietary lipid (L21) and temperature changes. Different diets showed a significantly different gut microbiome layout, only at high temperature with L16 diet resulting in a higher load of Lactobacillus. On the contrary, no dietary impact on ecosystem diversity was observed, independently from the temperature. In addition, L16 diet in the HL transition favored an increase in Weissella and Bradyrhizobium genera in the gut microbiome, while in the final condition of LH transition, L21 diet favored a significant increase in Streptococcus and Bacillus. According to the results, the utilization of 16% dietary lipid levels in gilthead sea bream should be preferred during seasonal temperature changes in order to optimize feed utilization and gut health
Modelo automatizado de tipificación de daños materiales por vicios o defectos que afecten a elementos de terminación y acabado en edificación
Users that detect defects in the termination of building elements frequently go to courts of justice claiming reparations and/or compensations. This situation generates in the intervening agents doubts and uncertainties about the responsibilities, consequences and penalties that they have to pay to compensate for that deficiencies. The object of present investigation is to propose and validate an automated model in the form of “predictive system” based on a software application “Expert System”. Using this software you can identify and classify these defects.Los usuarios que detectan defectos en edificaciones recientemente acabadas con frecuencia acuden a la vía judicial para reclamar su reparación. Ello genera en los agentes intervinientes cierta incertidumbre respecto a si serán o no condenados como responsables de dichos defectos. El objetivo de la presente investigación se centra en proponer y validar un modelo automatizado en forma de herramienta informatizada que, de manera sencilla, ayude a «tipificar de forma predictiva» los defectos más frecuentes y controvertidos a la hora de delimitar responsabilidades, es decir, los denominados «de terminación o acabado»
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