81 research outputs found
Local Behavior of the First-Order Gradient Correction to the Thomas-Fermi Kinetic Energy Functional
The first order gradient correction to the Thomas-Fermi functional, proposed
by Haq, Chattaraj and Deb (Chem. Phys. Lett. vol. 81, 8031, 1984) has been
studied by evaluating both the total kinetic energy and the local kinetic
energy density. For testing the kinetic energy density we evaluate its
deviation from an exact result through a quality factor, a parameter that
reflects the quality of the functionals in a better way than their relative
errors. The study is performed on two different systems: light atoms (up to
Z=18) and a noninteracting model of fermions confined in a Coulombic-type
potential. It is found than this approximation gives very low relative errors
and a better local behavior than any of the usual generalized gradient
approximation semilocal kinetic density functionals.Comment: 7 pages, 2 tables, 4 figure
Kinetic Energy Density Study of Some Representative Semilocal Kinetic Energy Functionals
There is a number of explicit kinetic energy density functionals for
non-interacting electron systems that are obtained in terms of the electron
density and its derivatives. These semilocal functionals have been widely used
in the literature. In this work we present a comparative study of the kinetic
energy density of these semilocal functionals, stressing the importance of the
local behavior to assess the quality of the functionals. We propose a quality
factor that measures the local differences between the usual orbital-based
kinetic energy density distributions and the approximated ones, allowing to
ensure if the good results obtained for the total kinetic energies with these
semilocal functionals are due to their correct local performance or to error
cancellations. We have also included contributions coming from the laplacian of
the electron density to work with an infinite set of kinetic energy densities.
For all the functionals but one we have found that their success in the
evaluation of the total kinetic energy are due to global error cancellations,
whereas the local behavior of their kinetic energy density becomes worse than
that corresponding to the Thomas-Fermi functional.Comment: 12 pages, 3 figure
Selección de una arquitectura many-core comercial como plataforma de tiempo real
Los procesadores many-core representan la evolución natural
de las arquitecturas de computadores de propósito general. Su aumento
de prestaciones y la contribución a la disminución de tamaño, peso y
consumo del sistema completo con respecto a los procesadores actuales
hace prever que serán usados también como plataformas para sistemas
de tiempo real en el futuro. En este artículo se identifi can los requisitos
que debería cumplir una arquitectura many-core para su utilización
en sistemas de tiempo real y se analizan varios procesadores many-core
existentes en el mercado para acabar seleccionando el mejor candidato.
Finalmente el artículo adelanta algunos de los retos esperables en el desarrollo
del soporte para aplicaciones de tiempo real sobre estos sistemasEste trabajo ha sido nanciado en parte por el Gobierno de España en el proyecto
TIN2014-56158-C4-2-P (M2C2)
Ergotropy and entanglement in critical spin chains
A subsystem of an entangled ground state is in a mixed state. Thus, if we
isolate this subsystem from its surroundings we may be able to extract work
applying unitary transformations, up to a maximal amount which is called
ergotropy. Once this work has been extracted, the subsystem will still contain
some bound energy above its local ground state, which can provide valuable
information about the entanglement structure. We show that the bound energy for
half a free fermionic chain decays as the square of the entanglement entropy
divided by the chain length, thus approaching zero for large system sizes, and
we conjecture that this relation holds for all 1D critical states
Efficacy of the mHealth application in patients with type 2 diabetes transitioning from inpatient to outpatient care: A randomized controlled clinical trial
Introduction: No studies have assessed the efficacy of telemedicine using a platform for recording and adjusting insulin doses in patients with diabetes mellitus type 2 (DM2) transitioning from inpatient to outpatient care. This study aimed to assess, in a population of patients with DM2, discharged from a tertiary referral hospital, whether treatment based on the use of an mHealth application was associated with better glycemic control at the 3-month follow-up, than standard care.
Methods: This open, randomized, controlled clinical trial included adult DM2 patients who were transitioning from inpatient to outpatient care. The efficacy and safety of patient management with and without mHealth was compared at the 3-month follow-up. The primary outcome was the change in the Glycosylated hemoglobin (HbA1c) levels. The secondary outcomes were the rates of hypoglycemic and hyperglycemic events and treatment satisfaction measured using the Insulin Treatment Satisfaction Questionnaire (ITSQ).
Results: In total, 86 patients (41 using mHealth) were included in the clinical trial. HbA1c levels showed a significant decrease in both groups. The mean HbA1c level was significantly lower in the mHealth group. Patients using mHealth showed decreased incidence rate ratios of hypoglycemia 3.0 mmol/L [<54 mg/dl], hypoglycemia ranging from 3.0 to 3.8 mmol/L [54 to 70 mg/dl] and severe hypoglycemia. The level of satisfaction assessed using the ITSQ was higher in the mHealth group.
Conclusion: Using mHealth in patients with DM2 transitioning from inpatient to outpatient care improves metabolic control and may reduce the hypoglycemia rates
Amphioxus functional genomics and the origins of vertebrate gene regulation.
Vertebrates have greatly elaborated the basic chordate body plan and evolved highly distinctive genomes that have been sculpted by two whole-genome duplications. Here we sequence the genome of the Mediterranean amphioxus (Branchiostoma lanceolatum) and characterize DNA methylation, chromatin accessibility, histone modifications and transcriptomes across multiple developmental stages and adult tissues to investigate the evolution of the regulation of the chordate genome. Comparisons with vertebrates identify an intermediate stage in the evolution of differentially methylated enhancers, and a high conservation of gene expression and its cis-regulatory logic between amphioxus and vertebrates that occurs maximally at an earlier mid-embryonic phylotypic period. We analyse regulatory evolution after whole-genome duplications, and find that-in vertebrates-over 80% of broadly expressed gene families with multiple paralogues derived from whole-genome duplications have members that restricted their ancestral expression, and underwent specialization rather than subfunctionalization. Counter-intuitively, paralogues that restricted their expression increased the complexity of their regulatory landscapes. These data pave the way for a better understanding of the regulatory principles that underlie key vertebrate innovations
Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)
Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters.
Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs).
Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001).
Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio
Gaia Data Release 3: Mapping the asymmetric disc of the Milky Way
With the most recent Gaia data release the number of sources with complete 6D
phase space information (position and velocity) has increased to well over 33
million stars, while stellar astrophysical parameters are provided for more
than 470 million sources, in addition to the identification of over 11 million
variable stars. Using the astrophysical parameters and variability
classifications provided in Gaia DR3, we select various stellar populations to
explore and identify non-axisymmetric features in the disc of the Milky Way in
both configuration and velocity space. Using more about 580 thousand sources
identified as hot OB stars, together with 988 known open clusters younger than
100 million years, we map the spiral structure associated with star formation
4-5 kpc from the Sun. We select over 2800 Classical Cepheids younger than 200
million years, which show spiral features extending as far as 10 kpc from the
Sun in the outer disc. We also identify more than 8.7 million sources on the
red giant branch (RGB), of which 5.7 million have line-of-sight velocities,
allowing the velocity field of the Milky Way to be mapped as far as 8 kpc from
the Sun, including the inner disc. The spiral structure revealed by the young
populations is consistent with recent results using Gaia EDR3 astrometry and
source lists based on near infrared photometry, showing the Local (Orion) arm
to be at least 8 kpc long, and an outer arm consistent with what is seen in HI
surveys, which seems to be a continuation of the Perseus arm into the third
quadrant. Meanwhile, the subset of RGB stars with velocities clearly reveals
the large scale kinematic signature of the bar in the inner disc, as well as
evidence of streaming motions in the outer disc that might be associated with
spiral arms or bar resonances. (abridged
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Gaia Early Data Release 3: The celestial reference frame (Gaia-CRF3)
Context. Gaia-CRF3 is the celestial reference frame for positions and proper motions in the third release of data from the Gaia mission, Gaia DR3 (and for the early third release, Gaia EDR3, which contains identical astrometric results). The reference frame is defined by the positions and proper motions at epoch 2016.0 for a specific set of extragalactic sources in the (E)DR3 catalogue. Aims. We describe the construction of Gaia-CRF3 and its properties in terms of the distributions in magnitude, colour, and astrometric quality. Methods. Compact extragalactic sources in Gaia DR3 were identified by positional cross-matching with 17 external catalogues of quasi-stellar objects (QSO) and active galactic nuclei (AGN), followed by astrometric filtering designed to remove stellar contaminants. Selecting a clean sample was favoured over including a higher number of extragalactic sources. For the final sample, the random and systematic errors in the proper motions are analysed, as well as the radio-optical offsets in position for sources in the third realisation of the International Celestial Reference Frame (ICRF3). Results. Gaia-CRF3 comprises about 1.6 million QSO-like sources, of which 1.2 million have five-parameter astrometric solutions in Gaia DR3 and 0.4 million have six-parameter solutions. The sources span the magnitude range G = 13-21 with a peak density at 20.6 mag, at which the typical positional uncertainty is about 1 mas. The proper motions show systematic errors on the level of 12 μas yr-1 on angular scales greater than 15 deg. For the 3142 optical counterparts of ICRF3 sources in the S/X frequency bands, the median offset from the radio positions is about 0.5 mas, but it exceeds 4 mas in either coordinate for 127 sources. We outline the future of Gaia-CRF in the next Gaia data releases. Appendices give further details on the external catalogues used, how to extract information about the Gaia-CRF3 sources, potential (Galactic) confusion sources, and the estimation of the spin and orientation of an astrometric solution
Gaia Data Release 3: reflectance spectra of Solar System small bodies
Stars and planetary system
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