A study to determine the flight characteristics and handling qualitites of variable geometry spacecraft. Volume 3: Low L/D concept with fold-down wings

A study was conducted to determine the flight characteristics and wing deployment transients for a variable geometry spacecraft concept having a hypersonic lift-to-drag ratio near 1.0, and employing fold-down wings. Unpowered flight conditions were considered throughout the study. The body of the spacecraft uses a trapezoidal cross section. The variable geometry wings, stowed in the sides of the vehicle, are deployed at transonic speeds

Tissue holder for experimental and Demonstration Surgery

Development of device for holding anatomical tissues during operations is discussed. Device consists of plastic dish with hemispherical recess in center to hold excised eyes. Low vacuum applied to underside of recess insures holding of part

The design features of the body of the portable electrocardiograph "ECG-EXPRESS"

The sequence of the industrial product shaping is specified, the main modeling characteristics of the configuration and some of its parts are designated subject to the electrocardiograph design and the technologies used for the production of its body

Do genetic structure and landscape heterogeneity impact color morph frequency in a polymorphic salamander?

Landscape heterogeneity plays an important role in population structure and divergence, particularly for species with limited vagility. Here, we used a landscape genetic approach to identify how landscape and environmental variables affect genetic structure and color morph frequency in a polymorphic salamander. The eastern red- backed salamander, Plethodon cinereus, is widely distributed in northeastern North America and contains two common color morphs, striped and unstriped, that are divergent in ecology, behavior, and physiology. To quantify population structure, rates of gene flow, and genetic drift, we amplified 10 microsatellite loci from 648 individuals across 28 sampling localities. This study was conducted in northern Ohio, where populations of P. cinereus exhibit an unusually wide range of morph frequency variation. To test whether genetic distance was more correlated with morph frequency, elevation, canopy cover, waterways, ecological niche or geographic distance, we used resistance distance and least cost path analyses. We then examined whether landscape and environmental variables, genetic distance or geographic distance were correlated with variation in morph frequency. Tests for population structure revealed three genetic clusters across our sampling range, with one cluster monomorphic for the striped morph. Rates of gene flow and genetic drift were low to moderate across sites. Genetic distance was most correlated with ecological niche, elevation and a combination of landscape and environmental variables. In contrast, morph frequency variation was correlated with waterways and geographic distance. Thus, our results suggest that selection is also an important evolutionary force across our sites, and a balance between gene flow, genetic drift and selection interact to maintain the two color morphs

A dedicated vascular access clinic for children on haemodialysis: Two years' experience

BACKGROUND: Arteriovenous fistula (AVF) formation for long-term haemodialysis in children is a niche discipline with little data for guidance. We developed a dedicated Vascular Access Clinic that is run jointly by a transplant surgeon, paediatric nephrologist, dialysis nurse and a clinical vascular scientist specialised in vascular sonography for the assessment and surveillance of AVFs. We report the experience and 2-year outcomes of this clinic. METHODS: Twelve new AVFs were formed and 11 existing AVFs were followed up for 2 years. All children were assessed by clinical and ultrasound examination. RESULTS: During the study period 12 brachiocephalic, nine basilic vein transpositions and two radiocephalic AVFs were followed up. The median age (interquartile range) and weight of those children undergoing new AVF creation were 9.4 (interquartile 3-17) years and 26.9 (14-67) kg, respectively. Pre-operative ultrasound vascular mapping showed maximum median vein and artery diameters of 3.0 (2-5) and 2.7 (2.0-5.3) mm, respectively. Maturation scans 6 weeks after AVF formation showed a median flow of 1277 (432-2880) ml/min. Primary maturation rate was 83 % (10/12). Assisted maturation was 100 %, with two patients requiring a single angioplasty. For the 11 children with an existing AVF the maximum median vein diameter was 14.0 (8.0-26.0) mm, and the median flow rate was 1781 (800-2971) ml/min at a median of 153 weeks after AVF formation. Twenty-two AVFs were used successfully for dialysis, a median kt/V of 1.97 (1.8-2.9), and urea reduction ratio of 80.7 % (79.3-86 %) was observed. One child was transplanted before the AVF was used. CONCLUSIONS: A multidisciplinary vascular clinic incorporating ultrasound assessment is key to maintaining young children on chronic haemodialysis via an AVF

Genetic Analysis of a Cryptic Contact Zone between Mitochondrial Clades of the Eastern Red-Backed Salamander, Plethodon cinereus

When evolutionarily divergent lineages adjoin their geographic ranges after a period of isolation, myriad outcomes can occur, from population anastomosis to the evolution of reproductive isolation by way of reinforcement. Hybrid zones represent natural experiments that may indicate whether lineages will maintain their evolutionary independence. Here, we report on a hybrid zone in the Eastern Red-Backed Salamander, Plethodon cinereus, a highly abundant and wide-ranging terrestrial salamander found in the northeastern United States and in southeastern Canada. An earlier study identified six distinct mitochondrial clades across the range of P. cinereus. Populations of two of these clades were as close as 9.6 km apart in Lorain County, Ohio, USA. To investigate the nature of this contact zone, we sampled 316 individuals from 16 sites along a 53-km transect, and analyzed 10 microsatellite loci and one mitochondrial locus. We found a clinal transition for mtDNA haplotypes. In contrast, most studies of terrestrial plethodontid salamanders commonly exhibit sharp boundaries between mtDNA clades. Microsatellite markers, however, revealed little differentiation and weak population structure, suggesting the nuclear cline, if it exists, lies outside of our sampling region. Explanations for the discordance between the mitochondrial DNA and our microsatellite data include lineage sorting, male-biased dispersal, or historical introgression of mtDNA, among other possibilities. We compare our results with other studies of introgression in terrestrial salamanders, and discuss the causes of mitonuclear discordance

On the R-Matrix Formulation of Deformed Algebras and Generalized Jordan-Wigner Transformations

The deformed algebra $\cal{A(R)}$, depending upon a Yang-Baxter R- matrix, is considered. The conditions under which the algebra is associative are discussed for a general number of oscillators. Four types of solutions satisfying these conditions are constructed and two of them can be represented by generalized Jordan-Wigner transformations.Our analysis is in some sense an extension of the boson realization of fermions from single-mode to multimode oscillators.Comment: 10+ii pages,preprint RBI-TH-10/93,Latex,(to appear in Europhys.Lett.

Heavy metal recovery from the fine fraction of solid waste incineration bottom ash by wet density separation

This work is aimed at exploring the recovery of heavy metals from the fine fraction of solid waste incineration bottom ash. For this study, wet-discharged bottom ash fine-fraction samples from full-scale treatment plants in Germany and Sweden were analyzed. The potential for the recovery of heavy metal compounds was investigated through wet density-separation with a shaking table. The feed materials were processed without any pre-treatment and the optimum processing conditions were determined by means of design of experiments. Tilt angle and stroke frequency were identified as the most relevant parameters, and the optimum settings were − 7.5° and 266 rpm, respectively. The obtained balanced copper enrichments (and yields) were 4.4 (41%), 6.2 (28%) and 2.4 (23%). A maximum copper enrichment of 14.5 with 2% yield was achieved, providing a concentrate containing 35.9 wt.% relevant heavy metal elements. This included 26.3 wt.% iron, 4.3 wt.% zinc and 3.8 wt.% copper. In conclusion, density separation with shaking tables can recover heavy metals from bottom ash fine fractions. Medium levels of heavy metal enrichment (e.g., for Cu 2.7–4.4) and yield (Cu: 26–41%) can be reached simultaneously. However, the separation performance also depends on the individual bottom ash sample