28,816 research outputs found

    RSRM-11 (36OW011) ballistics mass properties (STS-35)

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    The propulsion performance and reconstructed mass properties data from Thiolol's RSRM-11 motors which were assigned to the STS-35 launch are contained. The Thiokol manufacturing designations for the motors were 360W011A/360W011B, which are referred to as RSRM-11A and RSRM-B, respectively. The launch of STS-35 occurred on 2 December 1990 at the Eastern Test Range (ETR). The data contained herein was input to the STS-35 Flight Evaluation Report. The SRM propellant, TP-H1148, is a composite type solid propellants, formulated of polybutediene acrylic acid, acryonitrile terpolymer binder, epoxy curing agent, ammonium perchlorate oxidizer, and aluminum powder fuel. A small amount of burning rate catalyst (iron oxide) was added to achieve the desired propellant burn rate. The propellant evaluation and raw material information for the RSRM-11 are included. The ballistic performance presented was based on the Operational Flight Instrumentation (OFI) 12.5 sample per second pressure data for the steady state and tail off portion of the pressure trace. Recent studies have shown that the transducers are affected by the measuring system at KSC and temperature gradients created by the igniter heaters. Therefore, an adjustment to the data from each transducer is made to make the initial reading match the atmospheric pressure at the time of launch

    Long-range electron transfer in structurally engineered pentaammineruthenium (histidine-62) cytochrome c

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    In many biological processes, long-range electron transfer (ET) plays a key role. When the three-dimensional structures of proteins are accurately known, use of modified proteins and protein-protein complexes provides an experimental approach to study ET rates between two metal centers. For Ru(His)- modified proteins, the introduction of histidine residues at any desired surface location by site-directed mutagenesis opens the way for systematic investigations of ET pathways

    A projection method for statics and dynamics of lattice spin systems

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    A method based on Monte Carlo sampling of the probability flows projected onto the subspace of one or more slow variables is proposed for investigation of dynamic and static properties of lattice spin systems. We illustrate the method by applying it, with projection onto the order-parameter subspace, to the three-dimensional 3-state Potts model in equilibrium and to metastable decay in a three-dimensional 3-state kinetic Potts model.Comment: 4 pages, 3 figures, RevTex, final version to appear in Phys. Rev. Let

    Genome characterization and population genetic structure of the zoonotic pathogen, streptococcus canis

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    Background - Streptococcus canis is an important opportunistic pathogen of dogs and cats that can also infect a wide range of additional mammals including cows where it can cause mastitis. It is also an emerging human pathogen. Results - Here we provide characterization of the first genome sequence for this species, strain FSL S3-227 (milk isolate from a cow with an intra-mammary infection). A diverse array of putative virulence factors was encoded by the S. canis FSL S3-227 genome. Approximately 75% of these gene sequences were homologous to known Streptococcal virulence factors involved in invasion, evasion, and colonization. Present in the genome are multiple potentially mobile genetic elements (MGEs) [plasmid, phage, integrative conjugative element (ICE)] and comparison to other species provided convincing evidence for lateral gene transfer (LGT) between S. canis and two additional bovine mastitis causing pathogens (Streptococcus agalactiae, and Streptococcus dysgalactiae subsp. dysgalactiae), with this transfer possibly contributing to host adaptation. Population structure among isolates obtained from Europe and USA [bovine = 56, canine = 26, and feline = 1] was explored. Ribotyping of all isolates and multi locus sequence typing (MLST) of a subset of the isolates (n = 45) detected significant differentiation between bovine and canine isolates (Fisher exact test: P = 0.0000 [ribotypes], P = 0.0030 [sequence types]), suggesting possible host adaptation of some genotypes. Concurrently, the ancestral clonal complex (54% of isolates) occurred in many tissue types, all hosts, and all geographic locations suggesting the possibility of a wide and diverse niche. Conclusion - This study provides evidence highlighting the importance of LGT in the evolution of the bacteria S. canis, specifically, its possible role in host adaptation and acquisition of virulence factors. Furthermore, recent LGT detected between S. canis and human bacteria (Streptococcus urinalis) is cause for concern, as it highlights the possibility for continued acquisition of human virulence factors for this emerging zoonotic pathogen

    Optically Faint Microjansky Radio Sources

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    We report on the identifications of radio sources from our survey of the Hubble Deep Field and the SSA13 fields, both of which comprise the deepest radio surveys to date at 1.4 GHz and 8.5 GHz respectively. About 80% of the microjansky radio sources are associated with moderate redshift starburst galaxies or AGNs within the I magnitude range of 17 to 24 with a median of I = 22 mag. Thirty-one (20%) of the radio sources are: 1) fainter than I>I>25 mag, with two objects in the HDF IAB>I_{AB}>28.5, 2) often identified with very red objects IK>I-K>4, and 3) not significantly different in radio properties than the brighter objects. We suggest that most of these objects are associated with heavily obscured starburst galaxies with redshifts between 1 and 3. However, other mechanisms are discussed and cannot be ruled out with the present observations.Comment: to appear in Astrophysical Journal Letters, 3 figures, 1 tabl

    Contemporaneous VLBA 5 GHz Observations of Large Area Telescope Detected Blazars

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    The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long Baseline Array (VLBA). In total, 232 sources were observed with the VLBA. Ninety sources that were previously observed as part of the VLBA Imaging and Polarimetry Survey (VIPS) have been included in the sample, as well as 142 sources not found in VIPS. This very large, 5 GHz flux-limited sample of active galactic nuclei (AGNs) provides insights into the mechanism that produces strong γ-ray emission. In particular, we see that γ-ray emission is related to strong, uniform magnetic fields in the cores of the host AGN. Included in this sample are non-blazar AGNs such as 3C84, M82, and NGC 6251. For the blazars, the total VLBA radio flux density at 5 GHz correlates strongly with γ-ray flux. The LAT BL Lac objects tend to be similar to the non-LAT BL Lac objects, but the LAT flat-spectrum radio quasars (FSRQs) are significantly different from the non-LAT FSRQs. Strong core polarization is significantly more common among the LAT sources, and core fractional polarization appears to increase during LAT detection

    The Radio/Optical Catalog of the SSA13 Field

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    We present a 1.4-GHz catalog of 810 radio sources (560 sources in the complete sample) with 1.8" resolution found within a 17' radius in the SSA13 field (RA=13h12m,DEC=42d38'). The radio image from the VLA has an rms noise level of 4.82 microJy/beam at the field center, and Subaru optical images in r-band (6300A) and z-band (9200A) have a three-sigma detection magnitude of 26.1 and 24.9, respectively. 88% of the radio sources are identified with an optical counterpart, and there is significantly more reddening for objects fainter than 24-mag. The radio and optical parameters are tabulated, and source morphologies are displayed by radio contours overlaying optical false-color images. The radio structures show a wealth of complexity and these are classified into a small number of categories. About one-third of the radio sources are larger than 1.2" and their orientation is often similar to that of the associated galaxy or binary-galaxy system. The density of sources in the SSA13 field above 75 microJy is 0.40 per square arcmin, with a slope of -2.43 in the differential counts. The radio spectral index may steepen for sources below 75 microJy. We estimate that at most 40% of the microJansky radio sources are dominated by AGN processes.Comment: 50 pages, 14 figures of which fig 6 contains 33 parts. In press, Astrophysical Journal, Supp

    Exploring the parent population of beamed NLS1s: from the black hole to the jet

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    The aim of this work is to understand the nature of the parent population of beamed narrow-line Seyfert 1 galaxies (NLS1s), by studying the physical properties of three parent candidates samples: steep-spectrum radio-loud NLS1s, radio-quiet NLS1s and disk-hosted radio-galaxies. In particular, we focused on the black hole mass and Eddington ratio distribution and on the interactions between the jet and the narrow-line region.Comment: 6 pages, 2 figures, to appear in Proceedings of High Energy Phenomena in Relativistic Outflows (HEPRO) V, Workshop Series of the Argentinian Astronomical Societ

    Optical Sky Brightness at Cerro Tololo Inter-American Observatory from 1992 to 2006

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    We present optical UBVRI sky brightness measures from 1992 through 2006. The data are based on CCD imagery obtained with the CTIO 0.9-m, 1.3-m, and 1.5-m telescopes. The B- and V-band data are in reasonable agreement with measurements previously made at Mauna Kea, though on the basis of a small number of images per year there are discrepancies for the years 1992 through 1994. Our CCD-based data are not significantly different than values obtained at Cerro Paranal. We find that the yearly averages of V-band sky brightness are best correlated with the 10.7-cm solar flux taken 5 days prior to the sky brightness measures. This implies an average speed of 350 km/sec for the solar wind. While we can measure an enhancement of the night sky levels over La Serena 10 degrees above the horizon, at elevation angles above 45 degrees we find no evidence that the night sky brightness at Cerro Tololo is affected by artificial light of nearby towns and cities.Comment: 24 pages, 5 figures, to be published in the June, 2007, issue of the Publications of the Astron. Society of the Pacifi
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