Search

In Spain, PCR is the tool of choice for the diagnosis of congenital Chagas disease (CD) and serology for diagnosing chronic CD. A loop-mediated isothermal amplification test for Trypanosoma cruziDNA detection showed good analytical performance and ease of use.

We report on-off pointed MAMBO observations at 1.2 mm of 61 Spitzer-selected star-forming galaxies from the Spitzer Wide Area Infrared Extragalactic Legacy survey (SWIRE). The sources are selected on the basis of bright 24 mm fluxes (f 24 mm > 0.4 mJy) and of stellar dominated near-infrared spectral energy distributions in order to favor z [?] 2 starburst galaxies. The average 1.2 mm flux for the whole sample is 1.5 +- 0.2 mJy. Our analysis focuses on 29 sources in the Lockman Hole field where the average 1.2 mm flux (1.9 +- 0.3 mJy) is higher than in other fields (1.1 +- 0.2 mJy). The analysis of the multiwavelength spectral energy distributions indicates that these sources are starburst galaxies with far-infrared luminosities from 1012 to 1013.3 L , and stellar masses of [?]0.2-6 x 1011 M . Compared to submillimeter selected galaxies (SMGs), the SWIRE-MAMBO sources are among those with the largest 24 mm/1.2 mm flux ratios. The origin of such large ratios is investigated by comparing the average mid-infrared spectra and the stacked far-infrared spectral energy distributions of the SWIRE-MAMBO sources and of SMGs. The mid-infrared spectra, available for a handful of sources, exhibit strong polycyclic aromatic hydrocarbon (PAH) features, and a warm dust continuum. The warm dust continuum contributes [?]34% of the mid-infrared emission, and is likely associated with an AGN component. This contribution is consistent with what is found in SMGs. The large 24 mm/1.2 mm flux ratios are thus not due to AGN emission, but rather to enhanced PAH emission compared to SMGs. The analysis of the stacked far-infrared fluxes yields warmer dust temperatures than typically observed in SMGs. Our selection favors warm ultraluminous infrared sources at high-z, a class of objects that is rarely found in SMG samples. Indeed SMGs are not common among bright 24 mm sources (e.g., only about 20% of SMGs have f 24 mm > 0.4 mJy). Our sample is the largest Spitzer-selected sample detected at millimeter wavelengths currently available.

Hard X-ray surveys have uncovered a large population of heavily obscured AGNs. They also reveal a population of quasars with moderate obscuration at both visible and X-ray wavelengths. We use Chandra-selected samples of quasars from the ELAIS Deep X-ray Survey (EDXS) and the Chandra Deep Field-North to investigate the obscuration toward the nuclei of moderately obscured AGNs. We find an inverse correlation between the optical-to-X-ray flux ratio and the X-ray hardness ratio that can be interpreted as being due to obscuration at visible and X-ray wavelengths. We present detailed optical and near-infrared data for a sample of optically faint (R > 23) quasars from the EDXS. These are used to constrain the amount of rest-frame UV/optical reddening toward these quasars. It is found that optically faint quasars are mostly faint because of obscuration, not because they are intrinsically weak. After correcting for reddening, the optical magnitudes of most of these quasars are similar to the brighter quasars at these X-ray fluxes. Combining with gas column densities inferred from the X-ray observations, we consider the gas-to-dust ratios of the obscuring matter. We find that the quasars generally have higher gas-to-dust absorption than that seen in the Milky Way, similar to what has been found for nearby Seyfert galaxies. We consider the possible existence of a large population of X-ray sources that have optical properties of type 1 (unobscured) quasars but X-ray properties of type 2 (obscured) quasars. However, we find that such sources only contribute about 6% of the 0.5-8 keV X-ray background. Finally, we show that the observed distribution of optical-to-X-ray flux ratios of quasars at z > 1 is skewed to low values compared to the intrinsic distribution as a result of the fact that the observed-frame R-band light is emitted in the UV and is more easily obscured than hard X-rays.

The SIRTF Wide-Area Infrared Extragalactic Survey (SWIRE), the largest SIRTF Legacy program, is a wide-area imaging survey to trace the evolution of dusty, star-forming galaxies, evolved stellar populations, and active galactic nuclei (AGNs) as a function of environment, from redshifts z [?] 3 to the current epoch. SWIRE will survey seven high-latitude fields, totaling 60-65 deg2 in all seven SIRTF bands: Infrared Array Camera (IRAC) 3.6, 4.5, 5.6, and 8 um and Multiband Imaging Photometer for SIRTF (MIPS) 24, 70, and 160 um. Extensive modeling suggests that the Legacy Extragalactic Catalog may contain in excess of 2 million IR-selected galaxies, dominated by (1) [?]150,000 luminous infrared galaxies (LIRGs; LFIR > 1011 L[?]) detected by MIPS (and significantly more detected by IRAC), [?]7000 of these with z > 2; (2) 1 million IRAC-detected early-type galaxies ([?]2 x 105 with z > 1 and [?]10,000 with z > 2); and (3) [?]20,000 classical AGNs detected with MIPS, plus significantly more dust-obscured quasi-stellar objects/AGNs among the LIRGs. SWIRE will provide an unprecedented view of the evolution of galaxies, structure, and AGNs.The key scientific goals of SWIRE are (1) to determine the evolution of actively star forming and passively evolving galaxies in order to understand the history of galaxy formation in the context of cosmic structure formation; (2) to determine the evolution of the spatial distribution and clustering of evolved galaxies, starbursts, and AGNs in the key redshift range 0.5 < z < 3 over which much of cosmic evolution has occurred; and (3) to determine the evolutionary relationship between "normal galaxies" and AGNs and the contribution of AGN accretion energy versus stellar nucleosynthesis to the cosmic backgrounds. The large area of SWIRE is important to establish statistically significant population samples over enough volume cells that we can resolve the star formation history as a function of epoch and environment, i.e., in the context of structure formation. The large volume is also optimized for finding rare objects.The SWIRE fields are likely to become the next generation of large "cosmic windows" into the extragalactic sky. They have been uniquely selected to minimize Galactic cirrus emission over large scales. The Galaxy Evolution Explorer will observe them as part of its deep 100 deg2 survey, as will Herschel. SWIRE includes [?]9 deg2 of the unique large-area XMM Large Scale Structure hard X-ray imaging survey and is partly covered by the UKIDSS deep J and K survey. An extensive optical/near-IR imaging program is underway from the ground.The SWIRE data are nonproprietary; catalogs and images will be released twice yearly, beginning about 11 months after SIRTF launch. Details of the data products and release schedule are presented.

A letter to the editor about the celebration of National Train Day across the U.S. is presented.