2,446 research outputs found

    Adjustable high emittance gap filler

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    A flexible, adjustable refractory filler is disclosed for filling gaps between ceramic tiles forming the heat shield of a space shuttle vehicle, to protect its aluminum skin during atmospheric reentry. The easily installed and replaced filler consists essentially of a strip of ceramic cloth coated, at least along both its longitudinal edges with a room temperature vulcanizable silicone rubber compound with a high emittance colored pigment. The filler may have one or more layers as the gap width requires. Preferred materials are basket weave aluminoborosilicate cloth, and a rubber compounded with silicon tetraboride as the emittance agent and finely divided borosilicate glass containing about 7.5% B2O3 as high temperature binder. The filler cloth strip or tape is cut to proper width and length, inserted into the gap, and fastened with previously applied drops of silicone rubber adhesive

    On the monophyly of Macrolobium Schreb., an ecologically diverse neotropical tree genus (Fabaceae-Detarioideae)

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    Premise of research. The Neotropical endemic Macrolobium is one of the most species-rich genera (ca. 75 species) within subfamily Detarioideae (Fabaceae, alternatively Leguminosae). Two sections distinguished by floral morphology have been recognized in the past. Although morphologically diverse, species within the genus share several characters, including a single well-developed petal in adaxial position. However, previous analyses based on plastid markers have suggested that the genus is not monophyletic. We produce the most densely sampled molecular phylogeny of Macrolobium and test the monophyly of the genus and the two sections. Methodology. We analyzed nucleotide sequence data from the nuclear ribosomal internal transcribed spacer (ITS) and plastid (matK, trnG) genomes using Bayesian and maximum likelihood analyses. Pivotal results. The combined analysis retains Macrolobium as a monophyletic genus, with two well-supported subclades corresponding to the two recognized sections. Macrolobium pendulum is the only species placed in a section different from its taxonomic treatment. The relationships recovered with the plastid markers differ slightly from the combined and ITS analyses, but without significant support. Conclusions. Macrolobium is shown to be a monophyletic genus and to contain two well-supported and morphologically defined sections with differing Amazonian and Andean/Central American distributions corresponding to the Gentry pattern. Species are also found to group partly according to habitat preferences and leaf morphology. Both sections contain groups of multijugate and unijugate species, and there appear to have been multiple shifts of this character

    The epidemiology of chronic kidney disease (CKD) in rural East Africa: A population-based study.

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    BackgroundChronic kidney disease (CKD) may be common among individuals living in sub-Saharan Africa due to the confluence of CKD risk factors and genetic predisposition.MethodsWe ascertained the prevalence of CKD and its risk factors among a sample of 3,686 participants of a population-based HIV trial in rural Uganda and Kenya. Prevalent CKD was defined as a serum creatinine-based estimated glomerular filtration rate <60 mL/min/1.73m2 or proteinuria (urine dipstick ≥1+). We used inverse-weighting to estimate the population prevalence of CKD, and multivariable log-link Poisson models to assess the associations of potential risk factors with CKD.ResultsThe estimated CKD prevalence was 6.8% (95% CI 5.7-8.1%) overall and varied by region, being 12.5% (10.1-15.4%) in eastern Uganda, 3.9% (2.2-6.8%) in southwestern Uganda and 3.7% (2.7-5.1%) in western Kenya. Risk factors associated with greater CKD prevalence included age ≥60 years (adjusted prevalence ratio [aPR] 3.5 [95% CI 1.9-6.5] compared with age 18-29 years), HIV infection (aPR 1.6 [1.1-2.2]), and residence in eastern Uganda (aPR 3.9 [2.6-5.9]). However, two-thirds of individuals with CKD did not have HIV, diabetes, or hypertension as risk factors. Furthermore, we noted many individuals who did not have proteinuria had dipstick positive leukocyturia or hematuria.ConclusionThe prevalence of CKD is appreciable in rural East Africa and there are considerable regional differences. Conventional risk factors appear to only explain a minority of cases, and leukocyturia and hematuria were common, highlighting the need for further research into understanding the nature of CKD in sub-Saharan Africa

    Simultaneous Orthogonal Planarity

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    We introduce and study the OrthoSEFEk\textit{OrthoSEFE}-k problem: Given kk planar graphs each with maximum degree 4 and the same vertex set, do they admit an OrthoSEFE, that is, is there an assignment of the vertices to grid points and of the edges to paths on the grid such that the same edges in distinct graphs are assigned the same path and such that the assignment induces a planar orthogonal drawing of each of the kk graphs? We show that the problem is NP-complete for k3k \geq 3 even if the shared graph is a Hamiltonian cycle and has sunflower intersection and for k2k \geq 2 even if the shared graph consists of a cycle and of isolated vertices. Whereas the problem is polynomial-time solvable for k=2k=2 when the union graph has maximum degree five and the shared graph is biconnected. Further, when the shared graph is biconnected and has sunflower intersection, we show that every positive instance has an OrthoSEFE with at most three bends per edge.Comment: Appears in the Proceedings of the 24th International Symposium on Graph Drawing and Network Visualization (GD 2016

    Proper motions of the HH1 jet

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    We describe a new method for determining proper motions of extended objects, and a pipeline developed for the application of this method. We then apply this method to an analysis of four epochs of [S~II] HST images of the HH~1 jet (covering a period of 20\sim 20~yr). We determine the proper motions of the knots along the jet, and make a reconstruction of the past ejection velocity time-variability (assuming ballistic knot motions). This reconstruction shows an "acceleration" of the ejection velocities of the jet knots, with higher velocities at more recent times. This acceleration will result in an eventual merging of the knots in 450\sim 450~yr and at a distance of 80"\sim 80" from the outflow source, close to the present-day position of HH~1.Comment: 12 pages, 8 figure

    Circumventing antivector immunity: potential use of nonhuman adenoviral vectors

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    Adenoviruses are efficient gene delivery vectors based on their ability to transduce a wide variety of cell types and drive high-level transient transgene expression. While there have been advances in modifying human adenoviral (HAdV) vectors to increase their safety profile, there are still pitfalls that need to be further addressed. Preexisting humoral and cellular immunity against common HAdV serotypes limits the efficacy of gene transfer and duration of transgene expression. As an alternative, nonhuman AdV (NHAdV) vectors can circumvent neutralizing antibodies against HAdVs in immunized mice and monkeys and in human sera, suggesting that NHAdV vectors could circumvent preexisting humoral immunity against HAdVs in a clinical setting. Consequently, there has been an increased interest in developing NHAdV vectors for gene delivery in humans. In this review, we outline the recent advances and limitations of HAdV vectors for gene therapy and describe examples of NHAdV vectors focusing on their immunogenicity, tropism, and potential as effective gene therapy vehicles

    Predicting growth rates and recessions: assessing US leading indicators under real-time conditions

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    In this paper we analyze the power of various indicators to predict growth rates of aggregate production using real-time data. In addition, we assess their ability to predict turning points of the economy. We consider four groups of indicators: survey data, composite indicators, real economic indicators, and financial data. Almost all indicators are found to improve short-run growth forecasts whereas the results for four-quarter-ahead growth forecasts and the prediction of recession probabilities in general are mixed. We can confirm the result that an indicator suited to improve growth forecasts does not necessarily help to produce more accurate recession forecasts. Only composite leading indicators perform generally well in both forecasting exercises
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