The Orbital Period of Scorpius X-1

The orbital period of Sco X-1 was first identified by Gottlieb et al. (1975). While this has been confirmed on multiple occasions, this work, based on nearly a century of photographic data, has remained the reference in defining the system ephemeris ever since. It was, however, called into question when Vanderlinde et al. (2003) claimed to find the one-year alias of the historical period in RXTE/ASM data and suggested that this was the true period rather than that of Gottlieb et al. (1975). We examine data from the All Sky Automated Survey (ASAS) spanning 2001-2009. We confirm that the period of Gottlieb et al. (1975) is in fact the correct one, at least in the optical, with the one-year alias strongly rejected by these data. We also provide a modern time of minimum light based on the ASAS data.Comment: 3 pages, 2 figures, accepted for publication in the Astrophysical Journa

Endothelium-derived fibronectin regulates neonatal vascular morphogenesis in an autocrine fashion

Fibronectin containing alternatively spliced EIIIA and EIIIB domains is largely absent from mature quiescent vessels in adults, but is highly expressed around blood vessels during developmental and pathological angiogenesis. The precise functions of fibronectin and its splice variants during developmental angiogenesis however remain unclear due to the presence of cardiac, somitic, mesodermal and neural defects in existing global fibronectin KO mouse models. Using a rare family of surviving EIIIA EIIIB double KO mice, as well as inducible endothelial-specific fibronectin-deficient mutant mice, we show that vascular development in the neonatal retina is regulated in an autocrine manner by endothelium-derived fibronectin, and requires both EIIIA and EIIIB domains and the RGD-binding α5 and αv integrins for its function. Exogenous sources of fibronectin do not fully substitute for the autocrine function of endothelial fibronectin, demonstrating that fibronectins from different sources contribute differentially to specific aspects of angiogenesis

Cost-benefit analysis of aircraft design for environment using a fleet perspective and real options

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2005.Includes bibliographical references (leaves 101-105).Traditional multidisciplinary design optimization (MDO) approaches do not examine the costs associated with damage due to environmental factors and are usually implemented to examine one aircraft. The Environmental Design Space (EDS), an MDO tool, needs cost models that can incorporate the damage cost benefits of environmentally driven design changes both on a single aircraft and throughout a model fleet. It is important that the EDS framework also has a capability to assess the impact of future environmental technologies. Operating cost and fleet representation modules are created for the Environmental Design Space to calculate aggregated fleet effects for operating cost and emissions for current and evolving aircraft fleet. A case study involving a cost-benefit analysis of a NOx stringency mandate is conducted using the modules to assess the limitations of EDS. To assess the impacts of future environmental technologies, a real options framework is created using financial theory and applied to an engineering context. This framework is then used to derive a current monetary value for the option to include a noise reduction technology, trailing edge fan blowing, into an aircraft system.(cont.) Examining the trade-offs of the three differently designed replacement aircraft, the operating cost and fleet representation modules show that the minimum NOx aircraft has less of a cost-benefit fleet impact than that of the minimum fuel burn and minimum take-off weight. These results demonstrate a major trade-off between performance and environmental factors. The operating cost and fleet representation modules along with EDS assist in the design of aviation environmental policies by examining scenario fleet impacts. The real options framework using Monte Carlo software calculates the option value of incorporating new technology into the fleet.by Christopher Dennis Hynes.S.M

Carbon Paste Electrode Chemically Modified with Tris-4,7-Diphenyl-1,10-Phenanthroline Fe(II)

Chemistr

Radio sources in the Chandra Galactic Bulge Survey

We discuss radio sources in the Chandra Galactic Bulge Survey region. By cross-matching the X-ray sources in this field with the NRAO VLA Sky Survey archival data, we find 12 candidate matches. We present a classification scheme for radio/X-ray matches in surveys taken in or near the Galactic plane, taking into account other multiwavelength data. We show that none of the matches found here is likely to be due to coronal activity from normal stars because the radio to X-ray flux ratios are systematically too high. We show that one of the source could be a radio pulsar, and that one could be a planetary nebula, but that the bulk of the sources are likely to be background active galactic nuclei (AGN), with many confirmed through a variety of approaches. Several of the AGN are bright enough in the near-infrared (and presumably in the optical) to use as probes of the interstellar medium in the inner Galaxy

DNA Damage and Cytokine Production in Non-Target Irradiated Lymphocytes

In advanced radiotherapy, treatment of the tumor with high-intensity modulated fields is balanced with normal tissue sparing. However, the non-target dose delivered to surrounding healthy tissue within the irradiated volume is a potential cause for concern. Whether the effects observed are caused after exposure to out-of-field radiation or bystander effects through neighboring irradiated cells is not fully understood. The goal of this study was to determine the effect of exposure to out-of-field radiation in lymphocyte cell lines and primary blood cells. The role of cellular radiosensitivity in altering bystander responses in out-of-field exposed cells was also investigated. Target cells were positioned in a phantom in the center of the radiation field (in-field dose) and exposed to 2 Gy irradiation. Lymphocyte cell lines (C1, AT3ABR, Jurkat, THP-1, AT2Bi and AT3Bi) and peripheral blood were placed 1 cm away from the radiation field edge (out-offield dose) and received an average dose of 10.8 6 4.2 cGy. Double-stranded DNA damage, cell growth and gene expression were measured in the out-of-field cells. Radiosensitive AT3ABR and primary blood cells demonstrated the largest increase in c-H2AX foci after irradiation. Exposure of normal cells to bystander factors from irradiated radiosensitive cell lines also increased DNA damage. Expression of IL-1, IL-6, TNFa and TGFb after addition of bystander factors from radiosensitive cells showed differential effects in normally responding cells, with some evidence of an adaptive response observed. Exposure to out-of-field radiation induces DNA damage and reduces growth in radiosensitive cells. Bystander factors produced by directly irradiated cells in combination with out-of-field exposure may upregulate pro- and anti-inflammatory genes in responding cells of different radiosensitivities, with the potential of affecting the tumor microenvironment. A greater understanding of the radiobiological response in normal cells outside the primary treatment field would assist in radiation treatment planning and in reducing early and late toxicities

Characterization of the nodulation plasmid encoded chemoreceptor gene mcpG from Rhizobium leguminosarum

BACKGROUND: In general, chemotaxis in Rhizobium has not been well characterized. Methyl accepting chemotaxis proteins are sensory proteins important in chemotaxis of numerous bacteria, but their involvement in Rhizobium chemotaxis is unclear and merits further investigation. RESULTS: A putative methyl accepting chemotaxis protein gene (mcpG) of Rhizobium leguminosarum VF39SM was isolated and characterized. The gene was found to reside on the nodulation plasmid, pRleVF39d. The predicted mcpG ORF displayed motifs common to known methyl-accepting chemotaxis proteins, such as two transmembrane domains and high homology to the conserved methylation and signaling domains of well-characterized MCPs. Phenotypic analysis of mcpG mutants using swarm plates did not identify ligands for this putative receptor. Additionally, gene knockouts of mcpG did not affect a mutant strain's ability to compete for nodulation with the wild type. Notably, mcpG was found to be plasmid-encoded in all strains of R. leguminosarum and R. etli examined, though it was found on the nodulation plasmid only in a minority of strains. CONCLUSIONS: Based on sequence homology R. leguminosarum mcpG gene codes for a methyl accepting chemotaxis protein. The gene is plasmid localized in numerous Rhizobium spp. Although localized to the sym plasmid of VF39SM mcpG does not appear to participate in early nodulation events. A ligand for McpG remains to be found. Apparent McpG orthologs appear in a diverse range of proteobacteria. Identification and characterization of mcpG adds to the family of mcp genes already identified in this organism

Integrin-α5β1 is not required for mural cell functions during development of blood vessels but is required for lymphatic-blood vessel separation and lymphovenous valve formation

Integrin α5β1 is essential for vascular development but it remains unclear precisely where and how it functions. Here, we report that deletion of the gene encoding the integrin-α5 subunit (Itga5) using the Pdgfrb-Cre transgenic mouse line, leads to oedema, haemorrhage and increased levels of embryonic lethality. Unexpectedly, these defects were not caused by loss of α5 from Pdgfrb-Cre expressing mural cells (pericytes and vascular smooth muscle cells), which wrap around the endothelium and stabilise blood vessels, nor by defects in the heart or great vessels, but were due to abnormal development of the lymphatic vasculature. Reminiscent of the pathologies seen in the human lymphatic malformation, fetal cystic hygroma, α5 mutants display defects both in the separation of their blood and lymphatic vasculature and in the formation of the lymphovenous valves. As a consequence, α5-deficient mice develop dilated, blood-filled lymphatic vessels and lymphatic capillaries that are ectopically covered with smooth muscle cells. Analysis of the expression of Pdgfrb during lymphatic development suggests that these defects probably arise from loss of α5β1 integrin in subsets of specialised Prox1+Pdgfrb+ venous endothelial cells that are essential for the separation of the jugular lymph sac from the cardinal vein and formation of the lymphovenous valve leaflets.National Institutes of Health (U.S.) (PO1-HL66105)Cell Migration Consortium (GC11451.126452)National Cancer Institute (U.S.) (Koch Institute Support (core) Grant P30- CA14051)Howard Hughes Medical Institut

Links Between Optical and X-ray Light in Scorpius X-1

We observed the low-mass X-ray binary Sco X-1 for 12 nights simultaneously using the Rossi X-Ray Timing Explorer and the Otto Struve Telescope at McDonald Observatory at 1 second time resolution. This is among the most comprehensive simultaneous X-Ray/optical data sets of Sco X-1. Evidence of reprocessing was observed in the form of nine positive, near-zero lag peaks in the cross correlation function, eight of which were relatively small and took the shape of piecewise exponential functions. These peaks were initially identified by eye, after which a computational identification scheme was developed to confirm their significance. Based on their short lags (less than 4 seconds), as well as their occurrence on the flaring branch and soft apex, the small cross correlation features are likely to be caused by reprocessing off the outer disc, although the companion could still make a contribution to their tails. The Z track was parameterized using a rank number scheme so that the system's location on the track could be numerically defined. Plotting the results against the optical reveals an increasing step function when moving from the horizontal to the normal to the flaring branch, with differential optical levels at ~0.47, ~0.57, and ~1.1 respectively. An additional correlation between Z track location and the optical was found on the upper flaring branch. An optical intensity histogram reveals a transition region between the normal and flaring branches with only intermediate fluxes.Comment: Accepted for publication in the Monthly Notices of the Royal Astronomical Societ

Complete replication of hepatitis C virus in cell culture.

Many aspects of the hepatitis C virus (HCV) life cycle have not been reproduced in cell culture, which has slowed research progress on this important human pathogen. Here, we describe a full-length HCV genome that replicates and produces virus particles that are infectious in cell culture (HCVcc). Replication of HCVcc was robust, producing nearly 10(5) infectious units per milliliter within 48 hours. Virus particles were filterable and neutralized with a monoclonal antibody against the viral glycoprotein E2. Viral entry was dependent on cellular expression of a putative HCV receptor, CD81. HCVcc replication was inhibited by interferon-alpha and by several HCV-specific antiviral compounds, suggesting that this in vitro system will aid in the search for improved antivirals