Instituto Politécnico Nacional

About: Instituto Politécnico Nacional is a education organization based out in Mexico City, Mexico. It is known for research contribution in the topics: Population & Context (language use). The organization has 43351 authors who have published 63315 publications receiving 938532 citations. The organization is also known as: Instituto Politécnico Nacional & Instituto Politecnico Nacional.

Radar: The Cassini Titan Radar Mapper

Abstract: The Cassini RADAR instrument is a multimode 13.8 GHz multiple-beam sensor that can operate as a synthetic-aperture radar (SAR) imager, altimeter, scatterometer, and radiometer. The principal objective of the RADAR is to map the surface of Titan. This will be done in the imaging, scatterometer, and radiometer modes. The RADAR altimeter data will provide information on relative elevations in selected areas. Surfaces of the Saturn’s icy satellites will be explored utilizing the RADAR radiometer and scatterometer modes. Saturn’s atmosphere and rings will be probed in the radiometer mode only. The instrument is a joint development by JPL/NASA and ASI. The RADAR design features significant autonomy and data compression capabilities. It is expected that the instrument will detect surfaces with backscatter coefficient as low as −40 dB.

Characterization of rhizobia that nodulate legume species of the genus Lespedeza and description of Bradyrhizobium yuanmingense sp. nov.

Abstract: Legume species belonging to the genus Lespedeza are annual or perennial herb or shrub plants that grow in the northern hemisphere. They are known for the formation of root nodules, but little information is available about their microsymbionts. In this study, 58 root-nodule isolates from Lespedeza spp., obtained from China and the USA, were characterized using numerical taxonomic analysis of phenotypic features, SDS-PAGE analysis of whole-cell proteins, DNA-DNA hybridization, 16S rRNA gene sequence analysis and cross-nodulation with selected legume species. From the results generated using these approaches, it was concluded that Lespedeza spp. were promiscuous hosts for rhizobia. Four main clusters of bacteria, which included 35 of the strains isolated from Lespedeza spp., were defined upon numerical taxonomic analysis; these groups corresponded to those determined from analyses of protein electrophoretic and DNA-DNA hybridization data. The four clusters were found to define strains belonging to one of four species, Sinorhizobium saheli, Bradyrhizobium japonicum, Bradyrhizobium elkanii or a novel species of the genus Bradyrhizobium. The strains of B. japonicum and B. elkanii were all from the USA soil samples, and their representative strains could not nodulate soybean. The seven strains found to represent the novel Bradyrhizobium sp. were from China. These were differentiated from recognized species of the genus Bradyrhizobium by all of the taxonomic methods used here; hence, it is proposed that the novel strains isolated from Lespedeza spp. represent a novel species of the genus Bradyrhizobium, Bradyrhizobium yuanmingense. The type strain of the novel species, CCBAU 10071(T) (= CFNEB 101(T)), formed ineffective nodules on Medicago sativa and Melilotus albus but did not nodulate soybean. The other 23 bacterial strains isolated from Lespedeza spp. were found to form single branches or small groups (two to three strains) that were related to Bradyrhizobium, Mesorhizobium, Rhizobium and Sinorhizobium spp. on the basis of numerical taxonomic analysis, indicating the possibility that other rhizobial species are also associated with Lespedeza spp.

PRISM (Polarized Radiation Imaging and Spectroscopy Mission): An Extended White Paper

Abstract: PRISM (Polarized Radiation Imaging and Spectroscopy Mission) was proposed to ESA in May 2013 as a large-class mission for investigating within the framework of the ESA Cosmic Vision program a set of important scientific questions that require high resolution, high sensitivity, full-sky observations of the sky emission at wavelengths ranging from millimeter-wave to the far-infrared. PRISM's main objective is to explore the distant universe, probing cosmic history from very early times until now as well as the structures, distribution of matter, and velocity flows throughout our Hubble volume. PRISM will survey the full sky in a large number of frequency bands in both intensity and polarization and will measure the absolute spectrum of sky emission more than three orders of magnitude better than COBE FIRAS. The data obtained will allow us to precisely measure the absolute sky brightness and polarization of all the components of the sky emission in the observed frequency range, separating the primordial and extragalactic components cleanly from the galactic and zodiacal light emissions. The aim of this Extended White Paper is to provide a more detailed overview of the highlights of the new science that will be made possible by PRISM, which include: (1) the ultimate galaxy cluster survey using the Sunyaev-Zeldovich (SZ) effect, detecting approximately 106 clusters extending to large redshift, including a characterization of the gas temperature of the brightest ones (through the relativistic corrections to the classic SZ template) as well as a peculiar velocity survey using the kinetic SZ effect that comprises our entire Hubble volume; (2) a detailed characterization of the properties and evolution of dusty galaxies, where the most of the star formation in the universe took place, the faintest population of which constitute the diffuse CIB (Cosmic Infrared Background); (3) a characterization of the B modes from primordial gravity waves generated during inflation and from gravitational lensing, as well as the ultimate search for primordial non-Gaussianity using CMB polarization, which is less contaminated by foregrounds on small scales than the temperature anisotropies; (4) a search for distortions from a perfect blackbody spectrum, which include some nearly certain signals and others that are more speculative but more informative; and (5) a study of the role of the magnetic field in star formation and its interaction with other components of the interstellar medium of our Galaxy. These are but a few of the highlights presented here along with a description of the proposed instrument.

Photoacoustic techniques for trace gas sensing based on semiconductor laser sources.

Abstract: The paper provides an overview on the use of photoacoustic sensors based on semiconductor laser sources for the detection of trace gases We review the results obtained using standard, differential and quartz enhanced photoacoustic techniques

An Auxin Transport Independent Pathway Is Involved in Phosphate Stress-Induced Root Architectural Alterations in Arabidopsis. Identification of BIG as a Mediator of Auxin in Pericycle Cell Activation

Abstract: Arabidopsis (Arabidopsis thaliana) plants display a number of root developmental responses to low phosphate availability, including primary root growth inhibition, greater formation of lateral roots, and increased root hair elongation. To gain insight into the regulatory mechanisms by which phosphorus (P) availability alters postembryonic root development, we performed a mutant screen to identify genetic determinants involved in the response to P deprivation. Three low phosphate-resistant root lines (lpr1-1 to lpr1-3) were isolated because of their reduced lateral root formation in low P conditions. Genetic and molecular analyses revealed that all lpr1 mutants were allelic to BIG, which is required for normal auxin transport in Arabidopsis. Detailed characterization of lateral root primordia (LRP) development in wild-type and lpr1 mutants revealed that BIG is required for pericycle cell activation to form LRP in both high (1 mm) and low (1 μm) P conditions, but not for the low P-induced alterations in primary root growth, lateral root emergence, and root hair elongation. Exogenously supplied auxin restored normal lateral root formation in lpr1 mutants in the two P treatments. Treatment of wild-type Arabidopsis seedlings with brefeldin A, a fungal metabolite that blocks auxin transport, phenocopies the root developmental alterations observed in lpr1 mutants in both high and low P conditions, suggesting that BIG participates in vesicular targeting of auxin transporters. Taken together, our results show that auxin transport and BIG function have fundamental roles in pericycle cell activation to form LRP and promote root hair elongation. The mechanism that activates root system architectural alterations in response to P deprivation, however, seems to be independent of auxin transport and BIG.