1,182 research outputs found
Scalar Field Dark Matter: head-on interaction between two structures
In this manuscript we track the evolution of a system consisting of two
self-gravitating virialized objects made of a scalar field in the newtonian
limit. The Schr\"odinger-Poisson system contains a potential with
self-interaction of the Gross-Pitaevskii type for Bose Condensates. Our results
indicate that solitonic behavior is allowed in the scalar field dark matter
model when the total energy of the system is positive, that is, the two blobs
pass through each other as should happen for solitons; on the other hand, there
is a true collision of the two blobs when the total energy is negative.Comment: 8 revtex pages, 11 eps figures. v2 matches the published version.
v2=v1+ref+minor_change
Scalar Field Dark Matter: non-spherical collapse and late time behavior
We show the evolution of non-spherically symmetric balls of a
self-gravitating scalar field in the Newtonian regime or equivalently an ideal
self-gravitating condensed Bose gas. In order to do so, we use a finite
differencing approximation of the Shcr\"odinger-Poisson (SP) system of
equations with axial symmetry in cylindrical coordinates. Our results indicate:
1) that spherically symmetric ground state equilibrium configurations are
stable against non-spherical perturbations and 2) that such configurations of
the SP system are late-time attractors for non-spherically symmetric initial
profiles of the scalar field, which is a generalization of such behavior for
spherically symmetric initial profiles. Our system and the boundary conditions
used, work as a model of scalar field dark matter collapse after the turnaround
point. In such case, we have found that the scalar field overdensities tolerate
non-spherical contributions to the profile of the initial fluctuation.Comment: 8 revtex pages, 10 eps figures. Accepted for publication in PR
Interference pattern in the collision of structures in the BEC dark matter model: comparison with fluids
In order to explore nonlinear effects on the distribution of matter during
collisions within the Bose-Einstein condensate (BEC) dark matter model driven
by the Schr\"odinger-Poisson system of equations, we study the head-on
collision of structures and focus on the interference pattern formation in the
density of matter during the collision process. We explore the possibility that
the collision of two structures of fluid matter modeled with an ideal gas
equation of state also forms interference patterns and found a negative result.
Given that a fluid is the most common flavor of dark matter models, we conclude
that one fingerprint of the BEC dark matter model is the pattern formation in
the density during a collision of structures.Comment: 7 pages, 22 eps figure
La ecologÃa polÃtica en México ¿Dónde estamos y para dónde vamos?
En México, cada vez es más común la inscripción de enfoques de investigación y desarrollo académico al ámbito de la ecologÃa polÃtica. La irrupción de la ecologÃa polÃtica como disciplina y referencia teórica es muy alentadora para quienes analizamos los cambios ambientales desde una perspectiva social y polÃtica; sin embargo, creemos necesaria una revisión sobre el desarrollo
de esta disciplina en México, que nos permita delimitarla y evitar, asÃ, la simplificación y generalización de su campo. En este trabajo presentamos un panorama sintético del origen y evolución de la ecologÃa polÃtica y sus principales posturas teóricas en el ámbito internacional, asà como una revisión histórica general de los trabajos que, desde una perspectiva social, analizan la temática ambiental en México. Finalmente, discutimos los rasgos que caracterizan la ecologÃa polÃtica mexicana, las lÃneas de investigación más desarrolladas y las menos atendidas, asà como su importancia en el escenario ambiental del paÃs. Dada la gran cantidad y variedad de estudios
socioambientales en México, el trabajo puede considerarse un primer acercamiento a una caracterización e historia de la ecologÃa polÃtica de México, que brinda elementos para un futuro abordaje más completo y profundo del desarrollo de esta disciplina
El capital intelectual como medio generador de valor en la empresa industrial Procesadora S.A.C de la ciudad de Chiclayo-2008
La presente tesis plantea el tema del Capital Intelectual como medio generador de valor en la empresa industrial Procesadora S.A.C, de la ciudad de Chiclayo. El Capital Intelectual es un concepto muy amplio, que puede resumirse en un conjunto de atributos que debe poseer una empresa para llevar a cabo una gestión económica satisfactoria e inclusive sobrevivir en un entorno cada vez más competitivo; a través de esta investigación se determinará en qué medida el capital intelectual es un medio generador de valor en la empresa industrial Procesadora S.A.C. Además se demostrará que el capital intelectual (suma del capital humano, el capital estructural y el capital relacional), genera o no ventaja competitiva en la empresa industrial Procesadora S.A.C; para el desarrollo de esta tesis se utilizó las técnicas de observación, encuesta y entrevista .También se aplicó un modelo matemático de medición de intangibles en la empresa industrial Procesadora SAC.
Con la aplicación de este modelo se permitirá probar si el capital intelectual identificado como un intangible posee o no ventaja competitiva y esta a su vez genera valor en la empresa en mención. Obteniendo como resultado que el Capital Intelectual en la empresa Industrial Procesadora S.A.C, no genera ventaja competitiva en base a su capital intelectual por tanto no genera valor en la empresa.Tesi
Kinematic Properties and Stellar Populations of Faint Early-Type Galaxies. I. Velocity Dispersion Measurements of Central Coma Galaxies
We present velocity dispersion measurements for 69 faint early-type galaxies
in the core of the Coma cluster, spanning -22.0<M_R<-17.5 mag. We examine the
L-\sigma relation for our sample and compare it to that of bright ellipticals
from the literature. The distribution of the the faint early-type galaxies in
the L-sigma plane follows the relation L ~ \sigma^{2.01\pm0.36}, which is
significantly shallower from L ~ \sigma^4 as defined for the bright
ellipticals. While increased rotational support for fainter early-type galaxies
could account for some of the difference in slope, we show that it cannot
explain it. We also investigate the Colour-\sigma relation for our Coma
galaxies. Using the scatter in this relation, we constrain the range of galaxy
ages as a function of their formation epoch for different formation scenarios.
Assuming a strong coordination in the formation epoch of faint early-type
systems in Coma, we find that most had to be formed at least 6 Gyrs ago and
over a short 1 Gyr period.Comment: 15 pages including 3 tables and 7 figures, accepted for publication
in MNRA
The peculiar motions of early-type galaxies in two distant regions - II. The spectroscopic data
We present the spectroscopic data for the galaxies studied in the EFAR
project, which is designed to measure the properties and peculiar motions of
early-type galaxies in two distant regions. We have obtained 1319 spectra of
714 early-type galaxies over 33 observing runs on 10 different telescopes. We
describe the observations and data reductions used to measure redshifts,
velocity dispersions and the Mgb and Mg2 Lick linestrength indices. Detailed
simulations and intercomparison of the large number of repeat observations lead
to reliable error estimates for all quantities. The measurements from different
observing runs are calibrated to a common zeropoint or scale before being
combined, yielding a total of 706 redshifts, 676 velocity dispersions, 676 Mgb
linestrengths and 582 Mg2 linestrengths. The median estimated errors in the
combined measurements are dcz=20 km/s, dsigma/sigma=9.1%, dMgb/Mgb=7.2% and
dMg2=0.015 mag. Comparison of our measurements with published datasets shows no
systematic errors in the redshifts or velocity dispersions and only small
zeropoint corrections to bring our linestrengths onto the standard Lick system.
We have assigned galaxies to physical clusters by examining the line-of-sight
velocity distributions based on EFAR and ZCAT redshifts, together with the
projected distributions on the sky. We derive mean redshifts and velocity
dispersions for these clusters, which will be used in estimating distances and
peculiar velocities and to test for trends in the galaxy population with
cluster mass. The spectroscopic parameters presented here for 706 galaxies
combine high quality data, uniform reduction and measurement procedures, and
detailed error analysis. They form the largest single set of velocity
dispersions and linestrengths for early-type galaxies published to date.Comment: 27 pages, 18 figures, accepted by MNRA
2-Aminobenzoxazole-appended coumarins as potent and selective inhibitors of tumour-associated carbonic anhydrases
We have carried out the design, synthesis, and evaluation of a small library of 2-aminobenzoxazole-appended coumarins as novel inhibitors of tumour-related CAs IX and XII. Substituents on C-3 and/or C-4 positions of the coumarin scaffold, and on the benzoxazole moiety, together with the length of the linker connecting both units were modified to obtain useful structure-activity relationships. CA inhibition studies revealed a good selectivity towards tumour-associated CAs IX and XII (Ki within the mid-nanomolar range in most of the cases) in comparison with CAs I, II, IV, and VII (Ki > 10 µM); CA IX was found to be slightly more sensitive towards structural changes. Docking calculations suggested that the coumarin scaffold might act as a prodrug, binding to the CAs in its hydrolysed form, which is in turn obtained due to the esterase activity of CAs. An increase of the tether length and of the substituents steric hindrance was found to be detrimental to in vitro antiproliferative activities. Incorporation of a chlorine atom on C-3 of the coumarin moiety achieved the strongest antiproliferative agent, with activities within the low micromolar range for the panel of tumour cell lines tested.España MICINN (PID2020-116460RB-I00, PGC2018- 094503-B-C22)Junta de AndalucÃa (FQM134)Gobierno de Canarias ProID202001010
Apportioning sources of organic matter in streambed sediments: An integrated molecular and compound-specific stable isotope approach
We present a novel application for quantitatively apportioning sources of organic matter in streambed sediments via a coupled molecular and compound-specific isotope analysis (CSIA) of long-chain leaf wax n-alkane biomarkers using a Bayesian mixing model. Leaf wax extracts of 13 plant species were collected from across two environments (aquatic and terrestrial) and four plant functional types (trees, herbaceous perennials, and C3 and C4 graminoids) from the agricultural River Wensum catchment, UK. Seven isotopic (δ13C27, δ13C29, δ13C31, δ13C27–31, δ2H27, δ2H29, and δ2H27–29) and two n-alkane ratio (average chain length (ACL), carbon preference index (CPI)) fingerprints were derived, which successfully differentiated 93% of individual plant specimens by plant functional type. The δ2H values were the strongest discriminators of plants originating from different functional groups, with trees (δ2H27–29 = − 208‰ to − 164‰) and C3 graminoids (δ2H27–29 = − 259‰ to − 221‰) providing the largest contrasts. The δ13C values provided strong discrimination between C3 (δ13C27–31 = − 37.5‰ to − 33.8‰) and C4 (δ13C27–31 = − 23.5‰ to − 23.1‰) plants, but neither δ13C nor δ2H values could uniquely differentiate aquatic and terrestrial species, emphasizing a stronger plant physiological/biochemical rather than environmental control over isotopic differences. ACL and CPI complemented isotopic discrimination, with significantly longer chain lengths recorded for trees and terrestrial plants compared with herbaceous perennials and aquatic species, respectively. Application of a comprehensive Bayesian mixing model for 18 streambed sediments collected between September 2013 and March 2014 revealed considerable temporal variability in the apportionment of organic matter sources. Median organic matter contributions ranged from 22% to 52% for trees, 29% to 50% for herbaceous perennials, 17% to 34% for C3 graminoids and 3% to 7% for C4 graminoids. The results presented here clearly demonstrate the effectiveness of an integrated molecular and stable isotope analysis for quantitatively apportioning, with uncertainty, plant-specific organic matter contributions to streambed sediments via a Bayesian mixing model approach
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