1,743 research outputs found
Projections from Subvarieties
Let be an n-dimensional connected projective submanifold of
projective space. Let denote the projection from a
linear . Assuming that we have the induced
rational mapping . This article started as an
attempt to understand the structure of this mapping when has a lower
dimensional image. In this case of necessity we have is
nonempty. We have in this article studied a closely related question, which
includes many special cases including the case when the center of the
projection \pn q is contained in .
PROBLEM. Let be a proper connected k-dimensional projective submanifold
of an -dimensional projective manifold . Assume that . Let be a
very ample line bundle on such that is spanned by global
sections, where denotes the ideal sheaf of in . Describe the
structure of under the additional assumption that the image of
under the mapping associated to is lower dimensional
PSEUDOMONAS AVR AND HOP PROTEINS, THEIR ENCODING NUCLEIC ACIDS, AND USE THEREOF
One aspect of the present invention relates to isolated nucleic acid molecules encoding avirulence proteins or polypeptides of Pseudomonas syringae pv. syringae DC 3000, or nucleic acid moleculues which are complementary thereto. Expression vectors, host cells, and transgenic plants which include the DNA molecules of the present invention are also disclosed. Another aspect relates to the isolated proteins or polypeptides and compositions containing the same. The various nucleic acid molecules and proteins of the present invention can be used to impart disease resistance to a plant, make a plant hypersusceptible to colonization by nonpathogenic bacteria, modify a metabolic pathway in a cell, cause eukaryotic cell death and treat a cancerous condition, as well as inhibit programmed cell death
EXCEDE Technology Development III: First Vacuum Tests
This paper is the third in the series on the technology development for the
EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer) mission
concept, which in 2011 was selected by NASA's Explorer program for technology
development (Category III). EXCEDE is a 0.7m space telescope concept designed
to achieve raw contrasts of 1e6 at an inner working angle of 1.2 l/D and 1e7 at
2 l/D and beyond. This will allow it to directly detect and spatially resolve
low surface brightness circumstellar debris disks as well as image giant
planets as close as in the habitable zones of their host stars. In addition to
doing fundamental science on debris disks, EXCEDE will also serve as a
technological and scientific precursor for any future exo-Earth imaging
mission. EXCEDE uses a Starlight Suppression System (SSS) based on the PIAA
coronagraph, enabling aggressive performance.
We report on our continuing progress of developing the SSS for EXCEDE, and in
particular (a) the reconfiguration of our system into a more flight-like
layout, with an upstream deformable mirror and an inverse PIAA system, as well
as a LOWFS, and (b) testing this system in a vacuum chamber, including IWA,
contrast, and stability performance. The results achieved so far are 2.9e-7
contrast between 1.2-2.0 l/D and 9.7e-8 contrast between 2.0-6.0 l/D in
monochromatic light; as well as 1.4e-6 between 2.0-6.0 l/D in a 10% band, all
with a PIAA coronagraph operating at an inner working angle of 1.2 l/D. This
constitutes better contrast than EXCEDE requirements (in those regions) in
monochromatic light, and progress towards requirements in broadband light. Even
though this technology development is primarily targeted towards EXCEDE, it is
also germane to any exoplanet direct imaging space-based telescopes because of
the many challenges common to different coronagraph architectures and mission
requirements.Comment: 12 pages, 12 figures, to be published in proceedings of SPIE
Astronomical Telescopes + Instrumentation (2014
Classical scrapie prions in ovine blood are associated with B lymphocytes and platelet-rich plasma
<p>Abstract</p> <p>Background</p> <p>Classical scrapie is a naturally occurring transmissible spongiform encephalopathy of sheep and goats characterized by cellular accumulation of abnormal isoforms of prion protein (PrP<sup>Sc</sup>) in the central nervous system and the follicles of peripheral lymphoid tissues. Previous studies have shown that the whole blood and buffy coat blood fraction of scrapie infected sheep harbor prion infectivity. Although PrP<sup>Sc </sup>has been detected in peripheral blood mononuclear cells (PBMCs), plasma, and more recently within a subpopulation of B lymphocytes, the infectivity status of these cells and plasma in sheep remains unknown. Therefore, the objective of this study was to determine whether circulating PBMCs, B lymphocytes and platelets from classical scrapie infected sheep harbor prion infectivity using a sheep bioassay.</p> <p>Results</p> <p>Serial rectal mucosal biopsy and immunohistochemistry were used to detect preclinical infection in lambs transfused with whole blood or blood cell fractions from preclinical or clinical scrapie infected sheep. PrP<sup>Sc </sup>immunolabeling was detected in antemortem rectal and postmortem lymphoid tissues from recipient lambs receiving PBMCs (15/15), CD72<sup>+ </sup>B lymphocytes (3/3), CD21<sup>+ </sup>B lymphocytes (3/3) or platelet-rich plasma (2/3) fractions. As expected, whole blood (11/13) and buffy coat (5/5) recipients showed positive PrP<sup>Sc </sup>labeling in lymphoid follicles. However, at 549 days post-transfusion, PrP<sup>Sc </sup>was not detected in rectal or other lymphoid tissues in three sheep receiving platelet-poor plasma fraction.</p> <p>Conclusions</p> <p>Prion infectivity was detected in circulating PBMCs, CD72<sup>+ </sup>pan B lymphocytes, the CD21<sup>+ </sup>subpopulation of B lymphocytes and platelet-rich plasma of classical scrapie infected sheep using a sheep bioassay. Combining platelets with B lymphocytes might enhance PrP<sup>Sc </sup>detection levels in blood samples.</p
Predicting erythropoietin resistance in hemodialysis patients with type 2 diabetes
<p>Background: Resistance to ESAs (erythropoietin stimulating agents) is highly prevalent in hemodialysis patients with diabetes and associated with an increased mortality. The aim of this study was to identify predictors for ESA resistance and to develop a prediction model for the risk stratification in these patients.</p>
<p>Methods: A post-hoc analysis was conducted of the 4D study, including 1015 patients with type 2 diabetes undergoing hemodialysis. Determinants of ESA resistance were identified by univariate logistic regression analyses. Subsequently, multivariate models were performed with stepwise inclusion of significant predictors from clinical parameters, routine laboratory and specific biomarkers.</p>
<p>Results: In the model restricted to clinical parameters, male sex, shorter dialysis vintage, lower BMI, history of CHF, use of ACE-inhibitors and a higher heart rate were identified as independent predictors of ESA resistance. In regard to routine laboratory markers, lower albumin, lower iron saturation, higher creatinine and higher potassium levels were independently associated with ESA resistance. With respect to specific biomarkers, higher ADMA and CRP levels as well as lower Osteocalcin levels were predictors of ESA resistance.</p>
<p>Conclusions: Easily obtainable clinical parameters and routine laboratory parameters can predict ESA resistance in diabetic hemodialysis patients with good discrimination. Specific biomarkers did not meaningfully further improve the risk prediction of ESA resistance. Routinely assessed data can be used in clinical practice to stratify patients according to the risk of ESA resistance, which may help to assign appropriate treatment strategies.</p>
PSEUDOMONAS AVR AND HOP PROTEINS, THEIR ENCODING NUCLEIC ACIDS, AND USE THEREOF
One aspect of the present invention relates to isolated nucleic acid molecules encoding avirulence proteins or polypeptides of Pseudomonas syringae pv. syringae DC 3000, or nucleic acid moleculues which are complementary thereto. Expression vectors, host cells, and transgenic plants which include the DNA molecules of the present invention are also disclosed. Another aspect relates to the isolated proteins or polypeptides and compositions containing the same. The various nucleic acid molecules and proteins of the present invention can be used to impart disease resistance to a plant, make a plant hypersusceptible to colonization by nonpathogenic bacteria, modify a metabolic pathway in a cell, cause eukaryotic cell death and treat a cancerous condition, as well as inhibit programmed cell death
Deciphering Spectral Fingerprints of Habitable Extrasolar Planets
In this paper we discuss how we can read a planets spectrum to assess its
habitability and search for the signatures of a biosphere. After a decade rich
in giant exoplanet detections, observation techniques have now reached the
ability to find planets of less than 10 MEarth (so called Super-Earths) that
may potentially be habitable. How can we characterize those planets and assess
if they are habitable? The new field of extrasolar planet search has shown an
extraordinary ability to combine research by astrophysics, chemistry, biology
and geophysics into a new and exciting interdisciplinary approach to understand
our place in the universe. The results of a first generation mission will most
likely result in an amazing scope of diverse planets that will set planet
formation, evolution as well as our planet in an overall context.Comment: 17 pages, 10 figures, Astrobiology, 10, 1, 201
Investigations of γ′, γ″ and δ precipitates in heat-treated Inconel 718 alloy fabricated by selective laser melting
Inconel 718 alloy samples were fabricated by selective laser melting (SLM). Microstructure and precipitation in solution-heat-treated- and double-aging-SLM-made Inconel 718 were studied by scanning and transmission electron microscopy. Electron microscope observations showed that disc-shaped and cuboidal γ″, and circular γ′ precipitates with an average size of 10–50 nm developed within cellular γ austenite matrix. The simulated, experimentally observed electron diffraction patterns, and dark-field imaging further revealed that the precipitation of three variants of γ″ in the γ matrix occurred. The coarser acicular γ″, and globular as well as plate-like δ phases precipitated at grain boundaries and also within the interior of austenite matrix. The morphology, distribution and crystallography of these precipitates and their formation mechanisms were analyzed and discussed
The structure of an NDR/LATS kinase – mob complex reveals a novel kinase-coactivator system and substrate docking mechanism.
Eukaryotic cells commonly use protein kinases in signaling systems that relay information and control a wide range of processes. These enzymes have a fundamentally similar structure, but achieve functional diversity through variable regions that determine how the catalytic core is activated and recruited to phosphorylation targets. "Hippo" pathways are ancient protein kinase signaling systems that control cell proliferation and morphogenesis; the NDR/LATS family protein kinases, which associate with "Mob" coactivator proteins, are central but incompletely understood components of these pathways. Here we describe the crystal structure of budding yeast Cbk1-Mob2, to our knowledge the first of an NDR/LATS kinase-Mob complex. It shows a novel coactivator-organized activation region that may be unique to NDR/LATS kinases, in which a key regulatory motif apparently shifts from an inactive binding mode to an active one upon phosphorylation. We also provide a structural basis for a substrate docking mechanism previously unknown in AGC family kinases, and show that docking interaction provides robustness to Cbk1's regulation of its two known in vivo substrates. Co-evolution of docking motifs and phosphorylation consensus sites strongly indicates that a protein is an in vivo regulatory target of this hippo pathway, and predicts a new group of high-confidence Cbk1 substrates that function at sites of cytokinesis and cell growth. Moreover, docking peptides arise in unstructured regions of proteins that are probably already kinase substrates, suggesting a broad sequential model for adaptive acquisition of kinase docking in rapidly evolving intrinsically disordered polypeptides
Norspermidine is not a self-produced trigger for biofilm disassembly
SummaryFormation of Bacillus subtilis biofilms, consisting of cells encapsulated within an extracellular matrix of exopolysaccharide and protein, requires the polyamine spermidine. A recent study reported that (1) related polyamine norspermidine is synthesized by B. subtilis using the equivalent of the Vibrio cholerae biosynthetic pathway, (2) exogenous norspermidine at 25 μM prevents B. subtilis biofilm formation, (3) endogenous norspermidine is present in biofilms at 50–80 μM, and (4) norspermidine prevents biofilm formation by condensing biofilm exopolysaccharide. In contrast, we find that, at concentrations up to 200 μM, exogenous norspermidine promotes biofilm formation. We find that norspermidine is absent in wild-type B. subtilis biofilms at all stages, and higher concentrations of exogenous norspermidine eventually inhibit planktonic growth and biofilm formation in an exopolysaccharide-independent manner. Moreover, orthologs of the V. cholerae norspermidine biosynthetic pathway are absent from B. subtilis, confirming that norspermidine is not physiologically relevant to biofilm function in this species
- …