983 research outputs found

    Self-trapping of a binary Bose-Einstein condensate induced by interspecies interaction

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    The problem of self-trapping of a Bose-Einstein condensate (BEC) and a binary BEC in an optical lattice (OL) and double well (DW) is studied using the mean-field Gross-Pitaevskii equation. For both DW and OL, permanent self-trapping occurs in a window of the repulsive nonlinearity gg of the GP equation: gc1<g<gc2g_{c1}<g<g_{c2}. In case of OL, the critical nonlinearities gc1g_{c1} and gc2g_{c2} correspond to a window of chemical potentials μc1<μ<μc2\mu_{c1}<\mu<\mu_{c2} defining the band gap(s) of the periodic OL. The permanent self-trapped BEC in an OL usually represents a breathing oscillation of a stable stationary gap soliton. The permanent self-trapped BEC in a DW, on the other hand, is a dynamically stabilized state without any stationary counterpart. For a binary BEC with intraspecies nonlinearities outside this window of nonlinearity, a permanent self trapping can be induced by tuning the interspecies interaction such that the effective nonlinearities of the components fall in the above window

    Los restos de Sus scrofa (Artiodactyla, Mammalia) del yacimiento Pleistoceno de Pinilla del Valle (Madrid, España)

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    A morphologic and biometric study has been carried out on the fossil remains of Suidae derived from the first phase of excavation (1980-1989) at the late Pleistocene paleontological site of Cueva del Camino near Pinilla del Valle, north of Madrid. The material consists in 47 remains belonging to a minimum of 6 individuals. The results allow identifying the presence of the wild boar Sus scrofa, whose anatomical characteristics are compared with material from various European Pleistocene sites as well as present-day specimens. From the material obtained is this first phase of excavation stands out several cranial remains, because they are very scarce in coeval European sites, and are not recorded so far in other Spanish sites. The record of Sus scrofa agrees with the palaeoecological and palaeoenvironmental inferences displayed by previous studies from the whole faunal assemblage of the Cueva del Camino site.Se ha llevado a cabo un estudio morfológico y biométrico de los restos fósiles de Suidos excavados en el yacimiento del Pleistoceno superior de la Cueva del Camino, en el término de Pinilla del Valle (Madrid), comparándolos con los restos de otros yacimientos y con especímenes actuales. El material extraído comprende 47 elementos pertenecientes a un mínimo de 6 individuos, destacando la presencia de restos craneales, muy poco frecuentes en los yacimientos europeos de esta época, y ausentes en yacimientos españoles. Se han comprobado en los restos los caracteres anatómicos típicos de Sus scrofa, confirmándose las condiciones paleoambientales obtenidas del conjunto de la fauna

    IRS Spectra of Solar-Type Stars: \break A Search for Asteroid Belt Analogs

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    We report the results of a spectroscopic search for debris disks surrounding 41 nearby solar type stars, including 8 planet-bearing stars, using the {\it Spitzer Space Telescope}. With accurate relative photometry using the Infrared Spectrometer (IRS) between 7-34 \micron we are able to look for excesses as small as \sim2% of photospheric levels with particular sensitivity to weak spectral features. For stars with no excess, the 3σ3\sigma upper limit in a band at 30-34 μ\mum corresponds to \sim 75 times the brightness of our zodiacal dust cloud. Comparable limits at 8.5-13 μ\mum correspond to \sim 1,400 times the brightness of our zodiacal dust cloud. These limits correspond to material located within the <<1 to \sim5 AU region that, in our solar system, originates from debris associated with the asteroid belt. We find excess emission longward of \sim25 μ\mum from five stars of which four also show excess emission at 70 μ\mum. This emitting dust must be located around 5-10 AU. One star has 70 micron emission but no IRS excess. In this case, the emitting region must begin outside 10 AU; this star has a known radial velocity planet. Only two stars of the five show emission shortward of 25 \micron where spectral features reveal the presence of a population of small, hot dust grains emitting in the 7-20 μ\mum band. The data presented here strengthen the results of previous studies to show that excesses at 25 \micron and shorter are rare: only 1 star out of 40 stars older than 1 Gyr or 2.5\sim 2.5% shows an excess. Asteroid belts 10-30 times more massive than our own appear are rare among mature, solar-type stars

    Differentiation of Andean and Mesoamerican accessions in a proposed core collection of grain amaranths

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    Grain amaranths are made up of three New World species of pseudo-cereals with C4 photosynthesis from the dicotyledonous family Amaranthaceae and the genus Amaranthus. They originate in two ecoregions of the Americas, namely, the inter-Andean valleys of South America and the volcanic axis and lowlands of Mexico and Central America. These correspond to two centers of domestications for Andean and Mesoamerican crops, with one cultivated species found in the first region and two found in the latter region. To date, no core collection has been made for the grain amaranths in the United States Department of Agriculture (USDA) germplasm system. In this study, our objective was to create a core for the 2,899 gene bank accessions with collection site data by town or farm site of which 1,090 have current geo-referencing of latitude and longitude coordinates. We constituted the core with 260 genotypes of Amaranthus, which we evaluated with 90 single-nucleotide polymorphism markers. Our goal was to distinguish between Andean and Mesoamerican gene pools of amaranths, including the cultivated species and three possible progenitor or wild relative ancestors along with two more species in an outgroup. Population structure, clustering, and discriminant analysis for principal components showed that Andean species Amaranthus caudatus and Amaranthus quitensis shared fewer alleles with Mesoamerican species Amaranthus cruentus and Amaranthus hypochondriacus, compared to each group individually. Amaranthus hybridus was a bridge species that shared alleles with both regions. Molecular markers have the advantage over morphological traits at quickly distinguishing the Andean and Mesoamerican cultivars and have the added benefit of being useful for following inter-species crosses and introgression

    Role of lysosomal enzymes released by alveolar macrophages in the pathogenesis of the acute phase of hypersensitivity pneumonitis

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    Hydrolytic enzymes are the major constituents of alveolar macrophages (AM) and have been shown to be involved in many aspects of the inflammatory pulmonary response. The aim of this study was to evaluate the role of lysosomal enzymes in the acute phase of hypersensitivity pneumonitis (HPs). An experimental study on AM lysosomal enzymes of an HP-guinea-pig model was performed. The results obtained both in vivo and in vitro suggest that intracellular enzymatic activity decrease is, at least partly, due to release of lysosomal enzymes into the medium. A positive but slight correlation was found between extracellular lysosomal activity and four parameters of lung lesion (lung index, bronchoalveolar fluid total (BALF) protein concentration, BALF LDH and BALF alkaline phosphatase activities). All the above findings suggest that the AM release of lysosomal enzymes during HP is a factor involved, although possibly not the only one, in the pulmonary lesions appearing in this disease

    T-PHOT: A new code for PSF-matched, prior-based, multiwavelength extragalactic deconfusion photometry

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    We present T-PHOT, a publicly available software aimed at extracting accurate photometry from low-resolution images of deep extragalactic fields, where the blending of sources can be a serious problem for the accurate and unbiased measurement of fluxes and colours. T-PHOT has been developed within the ASTRODEEP project and it can be considered as the next generation to TFIT, providing significant improvements above it and other similar codes. T-PHOT gathers data from a high-resolution image of a region of the sky, and uses it to obtain priors for the photometric analysis of a lower resolution image of the same field. It can handle different types of datasets as input priors: i) a list of objects that will be used to obtain cutouts from the real high-resolution image; ii) a set of analytical models; iii) a list of unresolved, point-like sources, useful e.g. for far-infrared wavelength domains. We show that T-PHOT yields accurate estimations of fluxes within the intrinsic uncertainties of the method, when systematic errors are taken into account (which can be done thanks to a flagging code given in the output). T-PHOT is many times faster than similar codes like TFIT and CONVPHOT (up to hundreds, depending on the problem and the method adopted), whilst at the same time being more robust and more versatile. This makes it an optimal choice for the analysis of large datasets. In addition we show how the use of different settings and methods significantly enhances the performance. Given its versatility and robustness, T-PHOT can be considered the preferred choice for combined photometric analysis of current and forthcoming extragalactic optical to far-infrared imaging surveys. [abridged]Comment: 23 pages, 20 figures, 2 table

    Identification of z~>2 Herschel 500 micron sources using color-deconfusion

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    We present a new method to search for candidate z~>2 Herschel 500{\mu}m sources in the GOODS-North field, using a S500{\mu}m/S24{\mu}m "color deconfusion" technique. Potential high-z sources are selected against low-redshift ones from their large 500{\mu}m to 24{\mu}m flux density ratios. By effectively reducing the contribution from low-redshift populations to the observed 500{\mu}m emission, we are able to identify counterparts to high-z 500{\mu}m sources whose 24{\mu}m fluxes are relatively faint. The recovery of known z~4 starbursts confirms the efficiency of this approach in selecting high-z Herschel sources. The resulting sample consists of 34 dusty star-forming galaxies at z~>2. The inferred infrared luminosities are in the range 1.5x10^12-1.8x10^13 Lsun, corresponding to dust-obscured star formation rates (SFRs) of ~260-3100 Msun/yr for a Salpeter IMF. Comparison with previous SCUBA 850{\mu}m-selected galaxy samples shows that our method is more efficient at selecting high-z dusty galaxies with a median redshift of z=3.07+/-0.83 and 10 of the sources at z~>4. We find that at a fixed luminosity, the dust temperature is ~5K cooler than that expected from the Td-LIR relation at z<1, though different temperature selection effects should be taken into account. The radio-detected subsample (excluding three strong AGN) follows the far-infrared/radio correlation at lower redshifts, and no evolution with redshift is observed out to z~5, suggesting that the far-infrared emission is star formation dominated. The contribution of the high-z Herschel 500{\mu}m sources to the cosmic SFR density is comparable to that of SMG populations at z~2.5 and at least 40% of the extinction-corrected UV samples at z~4 (abridged).Comment: 33 pages in emulateapj format, 24 figures, 2 tables, accepted for publication in the ApJ

    Demand response program implementation methodology: A Colombian study case

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    The industrialization and urbanization are responsible for Greenhouse Gas (GHG) emissions and could generate energy shortage problems. The application of Demand Response (DR) programs enables the user to be empowered towards a conscious consumption of energy, allowing the reduction or displacement of the demand for electrical energy, contributing to the sustainable development of the sector and the operational efficiency of the electrical system, among others. A reference framework for this type of program is detailed along with a literature survey applied to the Colombian case. The considerations on the design of a methodology to the implementation of the DR pilot, considering if the pilot is in an interconnected system zone or non-interconnected system zone and the application of the design methodology in the modeling of three DR pilots in Colombia is presented. For the modeling of the pilots, the characteristics of the area and the base consumption of the users are considered, and the characteristics and assumptions of the pilot are also defined. Furthermore, the DR pilot in each zone considering four types of users is detailed. The results show the potential for energy reduction and displacement in different time bands for each zone, which allows determining the assessment of the benefits from a technical, financial, and environmental point of view, and the costs of each pilot in monetary terms, it not to compare the pilots with each other, but to illustrate the values that must be taken into account in those analyses. The sensitivity analysis of each pilot was also carried out, considering the variation of the benefit/cost relationship with the energy rate in peak hours vs. off-peak hours and the base energy rate in the area. The sensitivity analysis shows that, when varying the level of energy demand response and the number of pilot participants, the values are presented when the benefit/cost ratio is greater than 1. In addition, the paper provides specific recommendations related to the design of a methodology and the implementation in a pilot DR using simulation
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