4,058 research outputs found
Rationale, Scenarios, and Profiles for the Application of the Internet Protocol Suite (IPS) in Space Operations
This greenbook captures some of the current, planned and possible future uses of the Internet Protocol (IP) as part of Space Operations. It attempts to describe how the Internet Protocol is used in specific scenarios. Of primary focus is low-earth-orbit space operations, which is referred to here as the design reference mission (DRM). This is because most of the program experience drawn upon derives from this type of mission. Application profiles are provided. This includes parameter settings programs have proposed for sending IP datagrams over CCSDS links, the minimal subsets and features of the IP protocol suite and applications expected for interoperability between projects, and the configuration, operations and maintenance of these IP functions. Of special interest is capturing the lessons learned from the Constellation Program in this area, since that program included a fairly ambitious use of the Internet Protocol
Intensive Statin Therapy Is Associated With a Decrease in Adverse Events and Death Following Carotid Revascularization
The Highly Unusual Chemical Composition of the Hercules Dwarf Spheroidal Galaxy
We report on the abundance analysis of two red giants in the faint Hercules
dwarf spheroidal (dSph) galaxy. These stars show a remarkable deficiency in the
neutron-capture elements, while the hydrostatic alpha-elements (O, Mg) are
strongly enhanced. Our data indicate [Ba/Fe] and [Mg/Fe] abundance ratios of
<-2 dex and ~+0.8 dex, respectively, with essentially no detection of other
n-capture elements. In contrast to the only other dSph star with similar
abundance patterns, Dra 119, which has a very low metallicity at [Fe/H]=-2.95
dex, our objects, at [Fe/H]~-2.0 dex, are only moderately metal poor. The
measured ratio of hydrostatic/explosive alpha-elements indicates that high-mass
(~35 M_sun) Type II supernovae progenitors are the main, if not only,
contributors to the enrichment of this galaxy. This suggests that star
formation and chemical enrichment in the ultrafaint dSphs proceeds
stochastically and inhomogeneously on small scales, or that the IMF was
strongly skewed to high mass stars. The neutron capture deficiencies and the
[Co/Fe] and [Cr/Fe] abundance ratios in our stars are similar to those in the
extremely low metallicity Galactic halo. This suggests that either our stars
are composed mainly of the ejecta from the first, massive, population III stars
(but at moderately high [Fe/H]), or that SN ejecta in the Hercules galaxy were
diluted with ~30 times less hydrogen than typical for extreme metal-poor stars.Comment: 5 pages, 3 figures, accepted by Astrophysical Journal Letter
Variation in thromboembolic complications among patients undergoing commonly performed cancer operations
ObjectiveThere is widespread evidence that cancer confers an increased risk of deep venous thrombosis (DVT). This risk is thought to vary among different cancer types. The purpose of this study is to better define the incidence of thrombotic complications among patients undergoing surgical treatment for a spectrum of prevalent cancer diagnoses in contemporary practice.MethodsAll patients undergoing one of 11 cancer surgical operations (breast resection, hysterectomy, prostatectomy, colectomy, gastrectomy, lung resection, hepatectomy, pancreatectomy, cystectomy, esophagectomy, and nephrectomy) were identified by Current Procedural Terminology and International Classification of Diseases, Ninth Revision codes using the American College of Surgeons National Surgical Quality Improvement Program database (2007-2009). The study endpoints were DVT, pulmonary embolism (PE), and overall postoperative venous thromboembolic events (VTE) within 1 month of the index procedure. Multivariate logistic regression was utilized to calculate adjusted odds ratios for each endpoint.ResultsOver the study interval, 43,808 of the selected cancer operations were performed. The incidence of DVT, PE, and total VTE within 1 month following surgery varied widely across a spectrum of cancer diagnoses, ranging from 0.19%, 0.12%, and 0.28% for breast resection to 6.1%, 2.4%, and 7.3%, respectively, for esophagectomy. Compared with breast cancer, the incidence of VTE ranged from a 1.31-fold increase in VTE associated with gastrectomy (95% confidence interval, 0.73-2.37; P = .4) to a 2.68-fold increase associated with hysterectomy (95% confidence interval, 1.43-5.01; P = .002). Multivariate logistic regression revealed that inpatient status, steroid use, advanced age (≥60 years), morbid obesity (body mass index ≥35), blood transfusion, reintubation, cardiac arrest, postoperative infectious complications, and prolonged hospitalization were independently associated with increased risk of VTE.ConclusionsThe incidence of VTE and thromboembolic complications associated with cancer surgery varies substantially. These findings suggest that both tumor type and resection magnitude may impact VTE risk. Accordingly, such data support diagnosis and procedural-specific guidelines for perioperative VTE prophylaxis and can be used to anticipate the risk of potentially preventable morbidity
A Structural and Functional Comparison Between Infectious and Non-Infectious Autocatalytic Recombinant PrP Conformers
Infectious prions contain a self-propagating, misfolded conformer of the prion protein termed PrPSc. A critical prediction of the protein-only hypothesis is that autocatalytic PrPSc molecules should be infectious. However, some autocatalytic recombinant PrPSc molecules have low or undetectable levels of specific infectivity in bioassays, and the essential determinants of recombinant prion infectivity remain obscure. To identify structural and functional features specifically associated with infectivity, we compared the properties of two autocatalytic recombinant PrP conformers derived from the same original template, which differ by \u3e105-fold in specific infectivity for wild-type mice. Structurally, hydrogen/deuterium exchange mass spectrometry (DXMS) studies revealed that solvent accessibility profiles of infectious and non-infectious autocatalytic recombinant PrP conformers are remarkably similar throughout their protease-resistant cores, except for two domains encompassing residues 91-115 and 144-163. Raman spectroscopy and immunoprecipitation studies confirm that these domains adopt distinct conformations within infectious versus non-infectious autocatalytic recombinant PrP conformers. Functionally, in vitro prion propagation experiments show that the non-infectious conformer is unable to seed mouse PrPC substrates containing a glycosylphosphatidylinositol (GPI) anchor, including native PrPC. Taken together, these results indicate that having a conformation that can be specifically adopted by post-translationally modified PrPC molecules is an essential determinant of biological infectivity for recombinant prions, and suggest that this ability is associated with discrete features of PrPSc structure
A Structural and Functional Comparison Between Infectious and Non-Infectious Autocatalytic Recombinant PrP Conformers
Infectious prions contain a self-propagating, misfolded conformer of the prion protein termed PrPSc. A critical prediction of the protein-only hypothesis is that autocatalytic PrPSc molecules should be infectious. However, some autocatalytic recombinant PrPSc molecules have low or undetectable levels of specific infectivity in bioassays, and the essential determinants of recombinant prion infectivity remain obscure. To identify structural and functional features specifically associated with infectivity, we compared the properties of two autocatalytic recombinant PrP conformers derived from the same original template, which differ by \u3e105-fold in specific infectivity for wild-type mice. Structurally, hydrogen/deuterium exchange mass spectrometry (DXMS) studies revealed that solvent accessibility profiles of infectious and non-infectious autocatalytic recombinant PrP conformers are remarkably similar throughout their protease-resistant cores, except for two domains encompassing residues 91-115 and 144-163. Raman spectroscopy and immunoprecipitation studies confirm that these domains adopt distinct conformations within infectious versus non-infectious autocatalytic recombinant PrP conformers. Functionally, in vitro prion propagation experiments show that the non-infectious conformer is unable to seed mouse PrPC substrates containing a glycosylphosphatidylinositol (GPI) anchor, including native PrPC. Taken together, these results indicate that having a conformation that can be specifically adopted by post-translationally modified PrPC molecules is an essential determinant of biological infectivity for recombinant prions, and suggest that this ability is associated with discrete features of PrPSc structure
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