Many-Body Effects on Optical Carrier Cooling in Intrinsic Semiconductors at Low Lattice Temperatures

DTIC Science & Technology

2008-07-11

Fg, 78.40.Fy, 78.55.Cr I . INTRODUCTION It is well known that the optical properties of an atomic vapor are essentially determined by the properties...equal temperatures in the papers by Rupper et al.12 and by Sheik- Bahae et al.13 for both carriers and phonons cannot be applied to quasiequilibrium...2 + i 0 − 2e2 2 0 b 0 dk k2 rvck 21 − fek − fhk Eek + Ehk + i 02 − Eek + Ehk2 , 4 where 0 is the homogeneous

The vacuolar ATPase from Entamoeba histolytica: molecular cloning of the gene encoding for the B subunit and subcellular localization of the protein.

PubMed

Meléndez-Hernández, Mayra Gisela; Barrios, María Luisa Labra; Orozco, Esther; Luna-Arias, Juan Pedro

2008-12-23

Entamoeba histolytica is a professional phagocytic cell where the vacuolar ATPase plays a key role. This enzyme is a multisubunit complex that regulates pH in many subcellular compartments, even in those that are not measurably acidic. It participates in a wide variety of cellular processes such as endocytosis, intracellular transport and membrane fusion. The presence of a vacuolar type H+-ATPase in E. histolytica trophozoites has been inferred previously from inhibition assays of its activity, the isolation of the Ehvma1 and Ehvma3 genes, and by proteomic analysis of purified phagosomes. We report the isolation and characterization of the Ehvma2 gene, which encodes for the subunit B of the vacuolar ATPase. This polypeptide is a 55.3 kDa highly conserved protein with 34 to 80% identity to orthologous proteins from other species. Particularly, in silico studies showed that EhV-ATPase subunit B displays 78% identity and 90% similarity to its Dictyostelium ortholog. A 462 bp DNA fragment of the Ehvma2 gene was expressed in bacteria and recombinant polypeptide was used to raise mouse polyclonal antibodies. EhV-ATPase subunit B antibodies detected a 55 kDa band in whole cell extracts and in an enriched fraction of DNA-containing organelles named EhkOs. The V-ATPase subunit B was located by immunofluorescence and confocal microscopy in many vesicles, in phagosomes, plasma membrane and in EhkOs. We also identified the genes encoding for the majority of the V-ATPase subunits in the E. histolytica genome, and proposed a putative model for this proton pump. We have isolated the Ehvma2 gene which encodes for the V-ATPase subunit B from the E. histolytica clone A. This gene has a 154 bp intron and encodes for a highly conserved polypeptide. Specific antibodies localized EhV-ATPase subunit B in many vesicles, phagosomes, plasma membrane and in EhkOs. Most of the orthologous genes encoding for the EhV-ATPase subunits were found in the E. histolytica genome, indicating the

VizieR Online Data Catalog: Extinction map towards the Galactic bulge (Chen+, 2013)

NASA Astrophysics Data System (ADS)

Chen, B.; Schultheis, M.; Jiang, B.; Gonzalez, O. A.; Robin, A. C.; Rejkuba, M.; Minniti, D.

2012-11-01

We combine the observations with the Besancon model of the Galaxy to investigate the variations of extinction along different lines of sight towards the inner Galactic bulge as a function of distance. The full results are listed in Table 1 and Table 2. These results will be also added into the BEAM calculator webpage (http://mill.astro.puc.cl/BEAM/calculator.php). For each position we give the E(J-Ks), E(H-Ks) as well as the corresponding sigma for each distance bin starting from 1 to 10kpc. (2 data files).

Near-infrared reddening of extra-galactic giant molecular clouds in a face-on geometry

NASA Astrophysics Data System (ADS)

Kainulainen, J.; Juvela, M.; Alves, J.

2008-04-01

Aims: We describe the near-infrared reddening signature of giant molecular clouds (GMCs) in external galaxies. In particular, we examine the EJ-H and EH-K color excesses and the effective extinction law observed in discrete GMC regions. We also study the effect of the relative scale height of the GMC distribution to the color excesses, and to the observed mass function of GMCs when the masses are derived using color excess as a linear estimator of mass. Methods: We performed Monte Carlo radiative transfer simulations with 3D models of stellar radiation and clumpy dust distributions, resembling a face-on geometry. The scattered light is included in the models, and near-infrared color maps were calculated from the simulated data. We performed the simulations with different scale heights of GMCs and compared the color excesses and attenuation of light in different geometries. We extracted GMCs from the simulated color maps and compared the mass functions to the input mass functions. Results: The effective near-infrared reddening law, i.e. the ratio EJ-H/EH-K, has a value close to unity in GMC regions. The ratio depends significantly on the relative scale height of GMCs, ξ, and for ξ values 0.1...0.75, we find the typical ratios of 0.6...1.1. The effective extinction law turns out to be very flat in GMC regions. We find the ratios of apparent extinctions of AH^a/AKa = 1.35...1.55 and AJ^a/AHa = 1.15. The effect of the scattered flux on the effective reddening law, as well as on the effective extinction law, is significant. Regarding the GMC mass function, we find no correlation between the input and observed slopes of the mass functions. Instead, the observed slope reflects the parameter ξ and the dynamical range of the mass function. As the observed slope depends on the geometric parameters, which are not known, it is not possible to constrain the slope of the mass function using this technique. We estimate that only a fraction of 10...20% of the total mass of GMCs

Serpentinite Carbonation in the Pollino Massif (southern Italy) for CO2 Sequestration

NASA Astrophysics Data System (ADS)

Carmela Dichicco, Maria; Mongelli, Giovanni; Paternoster, Michele; Rizzo, Giovanna

2015-04-01

and medium to high-grade metamorphic rocks. Primary mantle minerals are olivine, clinopyroxene, orthopyroxene, and spinel whereas serpentine, magnetite, chlorite, and amphibole are pseudomorphic minerals. Olivine is replaced by serpentine forming a mesh texture and orthopyroxene is mostly altered to bastite. Water chemistry indicates serpentinites interact with meteoric water producing a Mg-HCO3 type water in a system open to CO2. Brown Jr., G.E., Calas, G., (2011) - Environmental mineralogy - understanding element behavior in ecosystems. Comptes Rendus Geoscience 343, 90-112. Huijgen W.JJ., and Comans R.N.J., (2003) - Carbon dioxide sequestrationby mineral carbonation. Report Number ECN-C-03-016, Energy research Centre of the Netherlands (ECN), Petten, the Netherlands. Keller PJ, Schmidt AD, Wittbrodt J, Stelzer EHK. (2008) - Reconstruction of zebrafish early embryonic development by scanned light sheet microscopy. Science 322: 1065-1069. Margiotta, S., Mongelli, G., Summa, V., Paternoster, M., Fiore S. (2012) - Trace element distribution and Cr(VI) speciation in Ca-HCO3 and Mg-HCO3 spring waters from the northern sector of the Pollino massif, southern Italy. Journal of Geochemical Exploration. Power I.M., Wilson S.A., Dipple G.M. (2013) - Serpentinite Carbonation for CO2 Sequestration. Elements, 9, 115-121. Sansone M.T.C., Prosser G., Rizzo G., Tartarotti P. (2012) - Spinel-peridotites of the Frido Unit ophiolites: evidence for oceanic evolution. Periodico di Mineralogia. 81, 35-59. 10.2451/2012PM0003