1,709 research outputs found
Gravitational anomalies signaling the breakdown of classical gravity
Recent observations for three types of astrophysical systems severely
challenge the GR plus dark matter scenario, showing a phenomenology which is
what modified gravity theories predict. Stellar kinematics in the outskirts of
globular clusters show the appearance of MOND type dynamics on crossing the
threshold. Analysis shows a ``Tully-Fisher'' relation in these systems,
a scaling of dispersion velocities with the fourth root of their masses.
Secondly, an anomaly has been found at the unexpected scales of wide binaries
in the solar neighbourhood. Binary orbital velocities cease to fall along
Keplerian expectations, and settle at a constant value, exactly on crossing the
threshold. Finally, the inferred infall velocity of the bullet cluster
is inconsistent with the standard cosmological scenario, where much smaller
limit encounter velocities appear. This stems from the escape velocity limit
present in standard gravity; the ``bullet'' should not hit the ``target'' at
more than the escape velocity of the joint system, as it very clearly did.
These results are consistent with extended gravity, but would require rather
contrived explanations under GR, each. Thus, observations now put us in a
situation where modifications to gravity at low acceleration scales cease to be
a matter of choice, to now become inevitable.Comment: 10 pages, 5 figures, Astrophysics and Space Science Proceedings 38,
4
Hydrodynamic Synchronisation of Model Microswimmers
We define a model microswimmer with a variable cycle time, thus allowing the
possibility of phase locking driven by hydrodynamic interactions between
swimmers. We find that, for extensile or contractile swimmers, phase locking
does occur, with the relative phase of the two swimmers being, in general,
close to 0 or pi, depending on their relative position and orientation. We show
that, as expected on grounds of symmetry, self T-dual swimmers, which are
time-reversal covariant, do not phase-lock. We also discuss the phase behaviour
of a line of tethered swimmers, or pumps. These show oscillations in their
relative phases reminiscent of the metachronal waves of cilia.Comment: 17 pages, 8 figure
Wide binaries as a critical test of Classical Gravity
Modified gravity scenarios where a change of regime appears at acceleration
scales have been proposed. Since for systems the
acceleration drops below at scales of around 7000 AU, a statistical
survey of wide binaries with relative velocities and separations reaching
AU and beyond should prove useful to the above debate. We apply the
proposed test to the best currently available data. Results show a constant
upper limit to the relative velocities in wide binaries which is independent of
separation for over three orders of magnitude, in analogy with galactic flat
rotation curves in the same acceleration regime. Our results are
suggestive of a breakdown of Kepler's third law beyond
scales, in accordance with generic predictions of modified gravity theories
designed not to require any dark matter at galactic scales and beyond.Comment: accepted for publication in EPJ
Conceptualización del transporte sostenible desde el comportamiento prosocial
Este documento informa de la necesidad de aumentar la eficacia de las
polÃticas de transporte sostenible sobre el cambio de actitudes para el uso
de diferentes modos de transporte a través de medidas de comportamiento
prosocial, que pueden generar obligaciones morales a tomar parte en actividades
prosociales mediante relaciones ocasionales incluidas en el modelo de activación de
la norma (NAM, Norm Activation Model).
La movilidad y el transporte sostenible aparecen como objetivo prioritario de intervención
por parte de las instituciones nacionales e internacionales. Las medidas adoptadas tienen que
ir acompañadas, para ser efectivas y producir un cambio de comportamiento hacia el transporte
público, de campañas que influyan en actitudes prosociales. La intención de reducir el uso del
automóvil es explicada principalmente por variables relacionadas con la moralidad y normas
personales, asà como las actitudes hacia el sistema de transporte (público o privado) más empleado
están muy ligadas a las experiencias individuales. La aplicación del modelo de activación de la
norma (NAM, Norm Activation Model) para una estrategia de transporte y movilidad sostenible,
representa la activación del comportamiento prosocial para producir cambios de comportamiento
de viaje de los ciudadanos y determinar una correlación entre polÃticas coherentes con las medidas
prosociales adoptadas.Toledo-Castillo, F.; Hernandez-San-Miguel, J.; Lloret-Catalá, M. (2012). Conceptualización del transporte sostenible desde el comportamiento prosocial. Plataforma Tecnológica Española de la Carretera (PTC). http://hdl.handle.net/10251/10316
A randomized study of nutritional supplementation in patients with unilateral wet age-related macular degeneration
The purpose of this study is evaluate the efficacy and safety of medicinal products con-taining the original Age-Related Eye Disease group (AREDS) formulation at doses approved in Europe (EU, control group; n = 59) with a product that adds DHA, lutein, zeaxanthin, resveratrol and hydroxytyrosol to the formula (intervention group; n = 50). This was a multicenter, random-ized, observer-blinded trial conducted in patients aged 50 years or older diagnosed with unilateral exudative Age related Macular Degeneration AMD. At month 12, the intervention did not have a significant differential effect on visual acuity compared with the control group, with an estimated treatment difference in Early Treatment Diabetic Retinopathy Study (ETDRS) of -1.63 (95% CI -0.83 to 4.09; p = 0.192). The intervention exhibited a significant and, in most cases, relevant effect in terms of a reduction in some inflammatory cytokines and a greater improvement in the fatty acid profile and serum lutein and zeaxantin concentration. In patients with unilateral wet AMD, the addition of lutein, zeaxanthin, resveratrol, hydroxytyrosol and DHA to the AREDS EU recommended doses in the short-term did not have a differential effect on visual acuity compared to a standard AREDS EU formula but, in addition to improving the fatty acid profile and increasing carotenoid serum levels, may provide a beneficial effect in improving the proinflammatory and proangiogenic profile of patients with AMD. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Journalism, journalism education and a region's integration: The case of Southeast Asia
The 50-year-old Association of Southeast Asian Nations (ASEAN) is now in its third year implementing the mechanics of regional integration. How does this region-wide development affect journalism in individual countries and in the region? This qualitative research sought to find out the meaning and implications of regional integration to journalism practice and education in Southeast Asia. There is enthusiasm over developing a model on ‘ASEAN-centered journalism and journalism education’, however there are country-level realities that news organisations and journalism schools face before proceeding to even attuning reportage and journalism instruction to the needs of ASEAN.Jeremaiah M. Opiniano, Aira L. Bagtas, Karl C. Basco, Raplh J. Hernandez,
Elyssa C. Lopez, Michael C. Rodolfo and Anne K. Vich
Developing and Evaluating a Game for the Assessment of Spatial Memory Using Auditory Stimuli
The combination of natural user interfaces and smart devices has become a new technological option to be exploited for the assessment of spatial memory. In this paper, we present an interactive game for assessing spatial memory using auditory stimuli. The distinct feature of our game is that it assesses the two types of information (i.e., acoustic and spatial) at the same time. We compared the performance of 100 children and 48 adults on the game with traditional neuropsychological tests. The performance on the game correlated with the performance on other traditional neuropsychological tests for the assessment of spatial short-term memory. Children and adults considered our game as easy to use, and all of them were satisfied with it. The results suggest that our game could be a valid tool for the identification of alterations in the spatial memory in both children and adults
Pharmacokinetic/Pharmacodynamic Modeling of Antipyretic and Anti-Inflammatory Effects of Naproxen in the Rat
Pharmacokinetic/pharmacodynamic modeling was used to characterize the antipyretic and anti-inflammatory effects of naproxen in rats. An indirect response model was used to describe the antipyretic effects of naproxen after short intravenous infusions. The model assumes that basal temperature (T(a)) is maintained by the balance of fever mediators given by a constant (zero order) rate of synthesis (K(syn)), and a first order rate of degradation (K(out)). After an intraperitoneal injection of lipopolysaccharide, the change in T(a) was modeled assuming an increase in fever mediators described as an input rate function [IR(t)] estimated nonparametrically. An inhibitory E(max) model adequately described the inhibition of IR(t) by naproxen. A more complex model was used to describe the anti-inflammatory response of oral naproxen in the carrageenin-induced edema model. Before carrageenin injection, physiological conditions are maintained by a balance of inflammation mediators given by K(syn) and K(out) (see above). After carrageenin injection, the additional synthesis of mediators is described by IR(t) (see above). Such mediators induced an inflammatory process, which is governed by a first order rate constant (K(IN)) that can be inhibited by the presence of naproxen in plasma. The sigmoidal E(max) model also well described the inhibition of K(IN) by naproxen. Estimates for IC(50) [concentration of naproxen in plasma eliciting half of maximum inhibition of IR(t) or K(IN)] were 4.24 and 4.13 microg/ml, for the antipyretic and anti-inflammatory effects, respectively
Efficient Recursion Method for Inverting Overlap Matrix
A new O(N) algorithm based on a recursion method, in which the computational
effort is proportional to the number of atoms N, is presented for calculating
the inverse of an overlap matrix which is needed in electronic structure
calculations with the the non-orthogonal localized basis set. This efficient
inverting method can be incorporated in several O(N) methods for
diagonalization of a generalized secular equation. By studying convergence
properties of the 1-norm of an error matrix for diamond and fcc Al, this method
is compared to three other O(N) methods (the divide method, Taylor expansion
method, and Hotelling's method) with regard to computational accuracy and
efficiency within the density functional theory. The test calculations show
that the new method is about one-hundred times faster than the divide method in
computational time to achieve the same convergence for both diamond and fcc Al,
while the Taylor expansion method and Hotelling's method suffer from numerical
instabilities in most cases.Comment: 17 pages and 4 figure
Identification and validation of common molecular targets of hydroxytyrosol
Hydroxytyrosol (HT) is involved in healthful activities and is beneficial to lipid metabolism. Many investigations focused on finding tissue-specific targets of HT through the use of different omics approaches such as transcriptomics and proteomics. However, it is not clear which (if any) of the potential molecular targets of HT reported in different studies are concurrently affected in various tissues. Following the bioinformatic analyses of publicly available data from a selection of in vivo studies involving HT-supplementation, we selected differentially expressed lipid metabolism-related genes and proteins common to more than one study, for validation in rodent liver samples from the entire selection. Four miRNAs (miR-802-5p, miR-423-3p, miR-30a-5p, and miR-146b-5p) responded to HT supplementation. Of note, miR-802-5p was commonly regulated in the liver and intestine. Our premise was that, in an organ crucial for lipid metabolism such as the liver, consistent modulation should be found for a specific target of HT even if different doses and duration of HT supplementation were used in vivo. Even though our results show inconsistency regarding differentially expressed lipid metabolism-related genes and proteins across studies, we found Fgf21 and Rora as potential novel targets of HT. Omics approaches should be fine-tuned to better exploit the available databases
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