243 research outputs found
Gains from diversification: a regret theory approach
In this paper we analyze a regret-averse individual best choice in a two risky assets portfolio. We extend previous literature and contribute new results by considering a model with two assets. We get the conditions for the regret-averse investor to diversify the portfolio. We additionally compare the behavior of the regret-averse investor with the behavior of its risk-averse counterpart. We characterize the conditions under which both types of agents behavior coincide.optimization; diversification; regret theory; quadrant dependent.
The Sunyaev-Zeldovich effect in superclusters of galaxies using gasdynamical simulations: the case of Corona Borealis
[Abridged] We study the thermal and kinetic Sunyaev-Zel'dovich (SZ) effect
associated with superclusters of galaxies using the MareNostrum Universe SPH
simulation. We consider superclusters similar to the Corona Borealis
Supercluster (CrB-SC). This paper is motivated by the detection at 33GHz of a
strong temperature decrement in the CMB towards the core of this supercluster.
Multifrequency observations with VSA and MITO suggest the existence of a
thermal SZ effect component in the spectrum of this cold spot, which would
account for roughly 25% of the total observed decrement. We identify nine
regions containing superclusters similar to CrB-SC, obtain the associated SZ
maps and calculate the probability of finding such SZ signals arising from hot
gas within the supercluster. Our results show that WHIM produces a thermal SZ
effect much smaller than the observed value. Neither can summing the
contribution of small clusters and galaxy groups in the region explain the
amplitude of the SZ signal. When we take into account the actual posterior
distribution from the observations, the probability that WHIM can cause a
thermal SZ signal like the one observed is <1%, rising up to a 3.2% when the
contribution of small clusters and galaxy groups is included. If the
simulations provide a suitable description of the gas physics, then we conclude
that the thermal SZ component of the CrB spot most probably arises from an
unknown galaxy cluster along the line of sight. The simulations also show that
the kinetic SZ signal associated with the supercluster cannot provide an
explanation for the remaining 75% of the observed cold spot in CrB.Comment: Accepted for publication in MNRAS. 14 pages, 9 figure
Editorial on Cerebral endothelial and glial cells are more than bricks in the Great Wall of the brain: insights into the way the blood-brain barrier actually works (celebrating the centenary of Goldman's experiments)
Carta editorial a la revista Frontiers in cellular neuroscience sobre las células endoteliales cerebrales y gliales. Se analiza la manera en que la barrera sangre-cerebro realmente funciona.Editorial letter to Frontiers in cellular neuroscience on cerebral endothelial and glial cells. It looks at how the blood-brain barrier actually works.peerReviewe
Drug and xenobiotic biotransformation in the blood–brain barrier: a neglected issue
Drug biotransformation is a crucial mechanism for facilitating the elimination of chemicals from the organism and for decreasing their pharmacological activity. Published evidence suggests that brain drug metabolism may play a role in the development of adverse drug reactions and in the clinical response to drugs and xenobiotics. The blood–brain barrier (BBB) has been regarded mainly as a physical barrier for drugs and xenobiotics, and little attention has been paid to the BBB as a drug-metabolizing barrier. The presence of drug-metabolizing enzymes in the BBB is likely to have functional implications because local metabolism may inactivate drugs or may modify the drug’s ability to cross the BBB, thus modifying drug response and the risk of developing adverse drug reactions. In this perspective paper, we discuss the expression of relevant xenobiotic metabolizing enzymes in the brain and in the BBB, and we cover current advances and future directions on the potential role of these BBB drug-metabolizing enzymes as modifiers of drug response
Chandra unveils a binary Active Galactic Nucleus in Mrk463
We analyse Chandra, XMM-Newton and HST data of the double-nucleus
Ultraluminous Infrared Galaxy (ULIRG), Mrk463. The Chandra detection of two
luminous ( and
erg cm s), unresolved nuclei in Mrk~463
indicates that this galaxy hosts a binary AGN, with a projected separation of
kpc ( arcsec). While the East nucleus was already
known to be a Seyfert 2 (and this is further confirmed by our Chandra detection
of a neutral iron line), this is the first unambiguous evidence in favour of
the AGN nature of the West nucleus. Mrk463 is therefore the clearest case so
far for a binary AGN, after NGC6240.Comment: 7 pages, 7 figures, accepted for publication in MNRA
A Numerical Study of Brown Dwarf Formation via Encounters of Protostellar Disks
The formation of brown dwarfs (BDs) due to the fragmentation of proto-stellar
disks undergoing pairwise encounters was investigated. High resolution allowed
the use of realistic initial disk models where both the vertical structure and
the local Jeans mass were resolved. The results show that objects with masses
ranging from giant planets to low mass stars can form during such encounters
from initially stable disks. The parameter space of initial spin-orbit
orientations and the azimuthal angles for each disk was explored. An upper
limit on the initial Toomre Q value of ~2 was found for fragmentation to occur.
Depending on the initial configuration, shocks, tidal-tail structures and mass
inflows were responsible for the condensation of disk gas. Retrograde disks
were generally more likely to fragment. When the interaction timescale was
significantly shorter than the disks' dynamical timescales, the proto-stellar
disks tended to be truncated without forming objects.
The newly-formed objects had masses ranging from 0.9 to 127 Jupiter masses,
with the majority in the BD regime. They often resided in star-BD multiples and
in some cases also formed hierarchical orbiting systems. Most of them had large
angular momenta and highly flattened, disk-like shapes. The objects had radii
ranging from 0.1 to 10 AU. The disk gas was assumed to be locally isothermal,
appropriate for the short cooling times in extended proto-stellar disks, but
not for condensed objects. An additional case with explicit cooling that
reduced to zero for optically thick gas was simulated to test the extremes of
cooling effectiveness and it was still possible to form objects in this case.
Detailed radiative transfer is expected to lengthen the internal evolution
timescale for these objects, but not to alter our basic results.Comment: 18 pages, 12 figures and 2 tables. Accepted for publication in MNRA
IMMUNOSUPPRESIVE EFFECTS OF THE METHANOLIC EXTRACT OF CHRYSOPHYLLUM CAINITO LEAVES ON MACROPHAGE FUNCTIONS
Background: The aim of this work was to evaluate the immunomodulatory effect of the methanol extract
(MeOH) from Chrysophyllum cainito leaves on the MΦs functions.
Material and Methods: Peritoneal murine MΦs isolated from Balb/c mice were treated with the MeOH extract
and stimulated with LPS. The effect on the phagocytosis was evaluated by flow cytometry assay. The nitric
oxide (NO) and hydrogen peroxide (H2O2) production was measured by the Griess reagent and phenol red
reaction, respectively. Levels of IL-6 and TNF-was measured using an ELISA kit. Viability of MΦs and Vero
cells was determined by the MTT method.
Results: The MeOH extract of C. cainito leaves inhibited significantly the phagocytosis, and decreased IL-6 and
TNF-α production as well as NO and H2O2 released by the MΦs, in a concentration-dependent manner. In
addition, MeOH extract of C. cainito showed low cytotoxicity effect against the cells.
Conclusion: These results suggest that MeOH extract of C. cainito leaves has an immunosuppressive effect on
murine MΦs, without effects on cell viability. GC-MS chromatogram analysis of MeOH extract showed that
lupeol acetate and alpha-amyrin acetate are the principal compounds
Developmental and tumoral vascularization is regulated by G protein-coupled receptor kinase 2
Tumor vessel dysfunction is a pivotal event in cancer progression. Using an in vivo neovascularization model,
we identified G protein–coupled receptor kinase 2 (GRK2) as a key angiogenesis regulator. An impaired
angiogenic response involving immature vessels was observed in mice hemizygous for Grk2 or in animals with
endothelium-specific Grk2 silencing. ECs isolated from these animals displayed intrinsic alterations in migration,
TGF-β signaling, and formation of tubular networks. Remarkably, an altered pattern of vessel growth
and maturation was detected in postnatal retinas from endothelium-specific Grk2 knockout animals. Mouse
embryos with systemic or endothelium-selective Grk2 ablation had marked vascular malformations involving
impaired recruitment of mural cells. Moreover, decreased endothelial Grk2 dosage accelerated tumor growth
in mice, along with reduced pericyte vessel coverage and enhanced macrophage infiltration, and this transformed
environment promoted decreased GRK2 in ECs and human breast cancer vessels. Our study suggests
that GRK2 downregulation is a relevant event in the tumoral angiogenic switch.Our laboratory is funded by grants from Ministerio de Educación
y Ciencia (SAF2011-23800), Fundación Ramón Areces,
The Cardiovascular Network (RECAVA) of Ministerio Sanidad
y Consumo-Instituto Carlos III (RD06-0014/0037 and
RD12/0042/0012), and Comunidad de Madrid (S-2010/BMD-
2332) to F. Mayor Jr. and Instituto Carlos III (PI11/00859), Fundación
Ramón Areces, and Fundación Rodríguez Pascual to P.
Penela. Marta Mendiola is supported by a postdoctoral research
contract from Fondo de Investigación Sanitaria (“Sara Borrell”
Programme), Instituto de Salud Carlos III
- …