3,697 research outputs found

    Extragalactic Source Counts in the Spitzer 24-micron Band: What Do We Expect From ISOCAM 15-micron Data and Models?

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    The comparison between the new Spitzer data at 24 micron and the previous ISOCAM data at 15 micron is a key tool to understand galaxy properties and evolution in the infrared and to interpret the observed number counts, since the combination of Spitzer with the ISO cosmological surveys provides for the first time the direct view of the Universe in the Infrared up to z~2. We present the prediction in the Spitzer 24-micron band of a phenomenological model for galaxy evolution derived from the 15-micron data. Without any ``a posteriori'' update, the model predictions seem to agree well with the recently published 24-micron extragalactic source counts, suggesting that the peak in the 24-micron counts is dominated by ``starburst'' galaxies like those detected by ISOCAM at 15 micron, but at higher redshifts (1 < z < 2 instead of 0.5 < z < 1.5).Comment: 8 pages: 4 pages of main text + 5 postscript figures, use aastex. Accepted for publication in ApJL. Replaced with the proof version (added missing references and corrected a few sentences

    The pattern determination of sea surface temperature distribution and chlorophyll a in the southern Caspian Sea using SOM model

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    Remote sensing has changed modern oceanography by proving synoptic periodic data which can be processed. Since the satellite data are usually too much and nonlinear, in most cases, it is difficult to distinguish the patterns from these images. In fact, SOM (Self-Organizing Maps) model is a type of ANN (Artificial Neural Network) that has the ability to distinguish the efficient patterns from the vast complex of satellite data. In this study, the sea surface temperature data and chlorophyll a related to a part of south Caspian Sea were investigated weekly by NOAA satellite for three years (2003–2005) and the annual and seasonal patterns were extracted (elicited) with their relative frequency using the SOM model. In all patterns the Caspian Sea coast has the highest chl-a and when you go away from the shore the rate decreases and when you approach to the middle parts the chl-a is of the least proportion on the sea surface

    The obscured X-ray source population in the HELLAS2XMM survey: the Spitzer view

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    Recent X-ray surveys have provided a large number of high-luminosity, obscured Active Galactic Nuclei (AGN), the so-called Type 2 quasars. Despite the large amount of multi-wavelength supporting data, the main parameters related to the black holes harbored in such AGN are still poorly known. Here we present the results obtained for a sample of eight Type 2 quasars in the redshift range 0.9-2.1 selected from the HELLAS2XMM survey, for which we used Ks-band, Spitzer IRAC and MIPS data at 24 micron to estimate bolometric corrections, black hole masses, and Eddington ratios.Comment: 6 pages, to appear in "The Multicoloured Landscape of Compact Objects and their Explosive Progenitors: Theory vs Observations" (Cefalu, Sicily, June 2006). Eds. L. Burderi et al. (New York: AIP

    On the nature of the ISO-selected sources in the ELAIS S2 region

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    We have studied the optical, near-IR and radio properties of a complete sample of 43 sources detected at 15-micron in one of the deeper ELAIS repeatedly observed region. The extragalactic objects in this sample have 15-micron flux densities in the range 0.4-10 mJy, where the source counts start diverging from no evolution models. About 90% of the sources (39 out of 43) have optical counterparts brighter than I=21 mag. Eight of these 39 sources have been identified with stars on the basis of imaging data, while for another 22 sources we have obtained optical spectroscopy, reaching a high identification percentage (30/43, ~70%). All but one of the 28 sources with flux density > 0.7 mJy are identified. Most of the extragalactic objects are normal spiral or starburst galaxies at moderate redshift (z_med~0.2); four objects are Active Galactic Nuclei. We have used the 15-micron, H_alpha and 1.4-GHz luminosities as indicators of star-formation rate and we have compared the results obtained in these three bands. While 1.4-GHz and 15-micron estimates are in good agreement, showing that our galaxies are forming stars at a median rate of ~40 Mo/yr, the raw H_alpha-based estimates are a factor ~5-10 lower and need a mean correction of ~2 mag to be brought on the same scale as the other two indicators. A correction of ~2 mag is consistent with what suggested by the Balmer decrements H_alpha/H_beta and by the optical colours. Moreover, it is intermediate between the correction found locally for normal spirals and the correction needed for high-luminosity 15-micron objects, suggesting that the average extinction suffered by galaxies increases with infrared luminosity.Comment: 19 pages, 11 figures (3 in JPEG format), MNRAS, accepte

    A New Method for ISOCAM Data Reduction - I. Application to the European Large Area ISO Survey Southern Field: Method and Results

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    We have developed a new data reduction technique for ISOCAM LW data and have applied it to the European Large Area ISO Survey (ELAIS) LW3 (15 micron) observations in the southern hemisphere (S1). This method, known as LARI technique and based on the assumption of the existence of two different time scales in ISOCAM transients (accounting either for fast or slow detector response), was particularly designed for the detection of faint sources. In the ELAIS S1 field we obtained a catalogue of 462 15 micron sources with signal-to-noise ratio >= 5 and flux densities in the range 0.45 - 150 mJy (filling the whole flux range between the Deep ISOCAM Surveys and the IRAS Faint Source Survey). The completeness at different flux levels and the photometric accuracy of this catalogue have been tested with simulations. Here we present a detailed description of the method and discuss the results obtained by its application to the S1 LW3 data.Comment: 20 pages, LaTeX, MNRAS style, 20 postscript figures, full catalogue not yet available at http://boas5.bo.astro.it/~elais/catalogues/. Accepted for publication in MNRA

    Acute liver injury and anorexia nervosa: A case report

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    Anorexia nervosa is an eating disorder characterized by restriction of energy intake leading to a significant decrease in body weight. While it is primarily a psychiatric disorder, numerous medical complications can occur. In this article we describe a case of a 25-year-old woman with a 12-year history of severe restrictive anorexia nervosa that was referred to the Emergency Service of our Hospital, transferred from a psychiatric institute, for severe weight loss, dehydration, and progressive increase in transaminases. During the hospital stay she developed an acute liver injury with an increase in transaminase level up to 40Ă— the ULN. Infective and immunological causes of acute hepatitis were excluded. In the suspect of severe starvation acute liver injury, we performed a nutritional assessment and started parenteral nutrition. After 15 days of parenteral nutrition, she gained 2.5 kg of body weight and liver tests were drastically reduced and nearly normal

    Single top production in the tt-channel at LHC: a realistic test of electroweak models

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    We compute the complete electroweak one-loop effect on the process of tt-channel single top production at LHC in the Standard Model and in the MSSM within the mSUGRA symmetry breaking scheme. We find that the one-loop electroweak SM effect is large, and decreases the cross section of an amount that is of the same size as that of the NLO QCD one. The genuine SUSY effect in the mSUGRA scheme, for a general choice of benchmark points, is rather small. It might become large and visible in more general scenarios around thresholds involving light stop and neutralino mass values.Comment: 28 pages, 10 eps figure

    Thermal quantum and classical correlations in two qubit XX model in a nonuniform external magnetic field

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    We investigate how thermal quantum discord (QD) and classical correlations (CC) of a two-qubit one-dimensional XX Heisenberg chain in thermal equilibrium depend on the temperature of the bath as well as on nonuniform external magnetic fields applied to two qubits and varied separately. We show that the behavior of QD differs in many unexpected ways from the thermal entanglement (EOF). For the nonuniform case (B1 = -B2), we find that QD and CC are equal for all values of (B1 = -B2) and for different temperatures. We show that, in this case, the thermal states of the system belong to a class of mixed states and satisfy certain conditions under which QD and CC are equal. The specification of this class and the corresponding conditions are completely general and apply to any quantum system in a state in this class satisfying these conditions. We further find that the relative contributions of QD and CC can be controlled easily by changing the relative magnitudes of B1 and B2. Finally, we connect our results with the monogamy relations between the EOF, CC and the QD of two qubits and the environment.Comment: 8 pages, 13 figures. We connect our results with the monogamy relations between the EOF, CC and the QD of two qubits and the environmen

    A hybrid pipeline for reconstruction and analysis of viral genomes at multi-organ level

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    Background: Advances in sequencing technologies have enabled the characterization of multiple microbial and host genomes, opening new frontiers of knowledge while kindling novel applications and research perspectives. Among these is the investigation of the viral communities residing in the human body and their impact on health and disease. To this end, the study of samples from multiple tissues is critical, yet, the complexity of such analysis calls for a dedicated pipeline. We provide an automatic and efficient pipeline for identification, assembly, and analysis of viral genomes that combines the DNA sequence data from multiple organs. TRACESPipe relies on cooperation among 3 modalities: compression-based prediction, sequence alignment, and de novo assembly. The pipeline is ultra-fast and provides, additionally, secure transmission and storage of sensitive data. Findings: TRACESPipe performed outstandingly when tested on synthetic and ex vivo datasets, identifying and reconstructing all the viral genomes, including those with high levels of single-nucleotide polymorphisms. It also detected minimal levels of genomic variation between different organs. Conclusions: TRACESPipe's unique ability to simultaneously process and analyze samples from different sources enables the evaluation of within-host variability. This opens up the possibility to investigate viral tissue tropism, evolution, fitness, and disease associations. Moreover, additional features such as DNA damage estimation and mitochondrial DNA reconstruction and analysis, as well as exogenous-source controls, expand the utility of this pipeline to other fields such as forensics and ancient DNA studies. TRACESPipe is released under GPLv3 and is available for free download at https://github.com/viromelab/tracespipe.Peer reviewe
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