Oxidation resistant, thoria-dispersed nickel-chromium-aluminum alloy

Modified thoria-dispersed nickel-chromium alloy has been developed that exhibits greatly improved resistance to high-temperature oxidation. Additions of aluminum have been made to change nature of protective oxide scale entirely and to essentially inhibit oxidation at temperatures up to 1260 C

Development of dispersion strengthened nickel-chromium alloy (Ni-Cr-ThO2) sheet for space shuttle vehicles, part 2

Two dispersion strengthened nickel base alloy systems were developed for use at temperatures up to 1204 C(2200 F); TD nickel chromium (TDNiCr) and TD nickel chromium aluminum (TDNiCrA1). They are considered candidate materials for use on the thermal protection systems of the space shuttle and for long term use in aircraft gas turbine engine applications. Improved manufacturing processes were developed for the fabrication of TDNiCr sheet and foil to specifications. Sheet rolling process studies and extrusion studies were made on two aluminum containing alloys: Ni-16%Cr-3.5%A1-2%ThO2 and Ni-16%Cr-5.0%A12%ThO2. Over 1600 kg.(3500 lb.) of plate, sheet, foil, bar and extrusion products were supplied to NASA Centers for technology studies

The surgical point of view of the geriatric patient — Urinary incontinence

Summary: Background: Urinary incontinence is one of the most frequent diseases in the ageing population. The aim of this manuscript is to present the current knowledge on urinary incontinence regarding (i) prevalence, (ii) pathogenesis, (iii) types, (iv) diagnostic assessment, and (v) treatment options. Methods: The current literature regarding urinary incontinence with special reference to the geriatric patient was reviewed. Results: According to a study performed recently in the Vienna area, 36.0% of women and 11.5% of men aged 70 years or older report urinary incontinence. Several factors, such as urodynamic changes, structural alterations of the lower urinary tract, increased sensory input, and impaired central control of the micturition reflex, contribute to the high prevalence of urinary incontinence with age. The four most common forms of urinary incontinence in the geriatric patient are combined stress/urge incontinence, pure urge incontinence, pure stress incontinence, and overflow incontinence. Diagnostic steps are classified into "mandatory”, "recommended”, and "indicated in selected cases only”. Particularly the "mandatory tests” are simple to perform and need no special equipment. Therapeutic options should be directed to the type of urinary incontinence as well as the physical and mental status of the patient. Conclusions: Urinary incontinence is highly prevalent with age. Conservative treatment is the therapy of choice for urge incontinence and mild to moderate forms of stress and overflow incontinence in the geriatric patien

An ancient anterior patterning system promotes Caudal repression and head formation in Ecdysozoa.

SummaryPosterior expression of Caudal is required for early embryonic development in nematodes, arthropods, and vertebrates [1–9]. In Drosophila, ectopic Caudal in anterior cells can induce head defects, and in Caenorhabditis the absence of Caudal in anterior embryonic cells is required for proper development [6, 10]. Anterior Caudal repression in these species is achieved through unrelated translational repressors, the homeodomain protein Bicoid [11] and the KH domain factor Mex-3 [6, 12], respectively. Here we report that the Mex-3 ortholog in the flour beetle Tribolium plays a crucial role in head formation and that Caudal in this species is repressed by the combined activities of Mex-3 and Zen-2, a protein sharing common ancestry with the dipteran morphogen Bicoid. We propose that Mex-3 represents an ancient “anterior” promoting factor common to all Ecdysozoa (and maybe all Bilateria), whose role has been usurped in higher dipterans by Bicoid

VIPP1 rods engulf membranes containing phosphatidylinositol phosphates

In cyanobacteria and plants, VIPP1 plays crucial roles in the biogenesis and repair of thylakoid membrane protein complexes and in coping with chloroplast membrane stress. In chloroplasts, VIPP1 localizes in distinct patterns at or close to envelope and thylakoid membranes. In vitro, VIPP1 forms higher-order oligomers of >1 MDa that organize into rings and rods. However, it remains unknown how VIPP1 oligomerization is related to function. Using time-resolved fluorescence anisotropy and sucrose density gradient centrifugation, we show here that Chlamydomonas reinhardtiiVIPP1 binds strongly to liposomal membranes containing phosphatidylinositol-4-phosphate (PI4P). Cryo-electron tomography reveals that VIPP1 oligomerizes into rods that can engulf liposomal membranes containing PI4P. These findings place VIPP1 into a group of membrane-shaping proteins including epsin and BAR domain proteins. Moreover, they point to a potential role of phosphatidylinositols in directing the shaping of chloroplast membranes

Gallot-Tanno Theorem for closed incomplete pseudo-Riemannian manifolds and applications

We extend the Gallot-Tanno Theorem to closed pseudo-Riemannian manifolds. It is done by showing that if the cone over a manifold admits a parallel symmetric $(0,2)-$tensor then it is Riemannian. Applications of this result to the existence of metrics with distinct Levi-Civita connections but having the same unparametrized geodesics and to the projective Obata conjecture are given. We also apply our result to show that the holonomy group of a closed $(O(p+1,q),S^{p,q})$-manifold does not preserve any nondegenerate splitting of $\R^{p+1,q}$.Comment: minor correction

Enhanced optical gain clamping for upstream packet based traffic on hybrid WDM/TDM-PON using fiber bragg grating

In this paper, we propose a method to mitigate the temporal power transients arising from Erbium doped fiber amplifiers (EDFAs) on packeted/bursty scenario. The technique, applicable on hybrid WDM/TDM-PON for extended reach, is based on a low power clamping provided by a distributed feedback (DFB) laser and a fiber Bragg grating (FBG). An mprovement in the data signal Q factor was achieved keeping the clamping control signal with a low power, accompanied by a maximum reduction in the gain excursion of 1.12 d

Shotgun metagenomic analysis of microbial communities from the Loxahatchee nature preserve in the Florida Everglades.

BackgroundCurrently, much is unknown about the taxonomic diversity and the mechanisms of methane metabolism in the Florida Everglades ecosystem. The Loxahatchee National Wildlife Refuge is a section of the Florida Everglades that is almost entirely unstudied in regard to taxonomic profiling. This short report analyzes the metagenome of soil samples from this Refuge to investigate the predominant taxa, as well as the abundance of genes involved in environmentally significant metabolic pathways related to methane production (nitrogen fixation and dissimilatory sulfite reduction).MethodsShotgun metagenomic sequencing using the Illumina platform was performed on 17 soil samples from four different sites within the Loxahatchee National Wildlife Refuge, and underwent quality control, assembly, and annotation. The soil from each sample was tested for water content and concentrations of organic carbon and nitrogen.ResultsThe three most common phyla of bacteria for every site were Actinobacteria, Acidobacteria, and Proteobacteria; however, there was variation in relative phylum composition. The most common phylum of Archaea was Euryarchaeota for all sites. Alpha and beta diversity analyses indicated significant congruity in taxonomic diversity in most samples from Sites 1, 3, and 4 and negligible congruity between Site 2 and the other sites. Shotgun metagenomic sequencing revealed the presence of biogeochemical biomarkers of particular interest (e.g., mrcA, nifH, and dsrB) within the samples. The normalized abundances of mcrA, nifH, and dsrB exhibited a positive correlation with nitrogen concentration and water content, and a negative correlation with organic carbon concentration.ConclusionThis Everglades soil metagenomic study allowed examination of wetlands biological processes and showed expected correlations between measured organic constituents and prokaryotic gene frequency. Additionally, the taxonomic profile generated gives a basis for the diversity of prokaryotic microbial life throughout the Everglades

Notes on a paper of Mess

These notes are a companion to the article "Lorentz spacetimes of constant curvature" by Geoffrey Mess, which was first written in 1990 but never published. Mess' paper will appear together with these notes in a forthcoming issue of Geometriae Dedicata.Comment: 26 page