Study of thermal insulation for airborne liquid hydrogen fuel tanks

A concept for a fail-safe thermal protection system was developed. From screening tests, approximately 30 foams, adhesives, and reinforcing fibers using 0.3-meter square liquid nitrogen cold plate, CPR 452 and Stafoam AA1602, both reinforced with 10 percent by weight of 1/16 inch milled OCF Style 701 Fiberglas, were selected for further tests. Cyclic tests with these materials in 2-inch thicknesses bonded on a 0.6-meter square cold plate with Crest 7410 adhesive systems, were successful. Zero permeability gas barriers were identified and found to be compatible with the insulating concept

Data report for the Siple Coast (Antarctica) project

This report presents data collected during three field seasons of glaciological studies in the Antarctica and describes the methods employed. The region investigated covers the mouths of Ice Streams B and C (the Siple Coast) and Crary Ice Rise on the Ross Ice Shelf. Measurements included in the report are as follows: surface velocity and deformation from repeated satellite geoceiver positions; surface topography from optical levelling; radar sounding of ice thickness; accumulation rates; near-surface densities and temperature profiles; and mapping from aerial photography

Topological twisted sigma model with H-flux revisited

In this paper we revisit the topological twisted sigma model with H-flux. We explicitly expand and then twist the worldsheet Lagrangian for bi-Hermitian geometry. we show that the resulting action consists of a BRST exact term and pullback terms, which only depend on one of the two generalized complex structures and the B-field. We then discuss the topological feature of the model.Comment: 16 pages. Appendix adde

Geochemistry of Yamato-82192, -86032 and -793274 lunar meteorites

The major and trace element compositions of lunar meteorites Yamato (Y)-82192,Y-86032 and Y-793274 were determined by neutron activation analysis. Y-82192 and Y-86032 are anorthositic lunar meteorites rich in Al_2O_3 and CaO and poor in FeO, MgO and incompatible elements. Although these meteorites are similar in composition to each other and other anorthositic lunar meteorites, they are distinct in several key compositional characteristics. Y-793274 is a basaltic lunar meteorite rich in FeO, MgO, Sc, Cr, Co, and incompatible elements and poor in Al_2O_3 and CaO compared to anorthositic lunar meteorites. It is similar in many ways to lunar meteorite EET87521 which is also a basaltic breccia. It is distinct from EET87521 in its higher proportion of highland material, its meteoritic contamination and regolith glass, and in the composition of its dominant basalt component. Y-793274 contains 65-75% magnesian VLT basalt, while EET87521 consists of ferroan VLT basalt. The eleven lunar meteorites probably represent eight distinct falls. Four are anorthositic and four are basaltic. This 50-50 proportion of highlands-mare material contrasts strongly with the 83-17 proportion derived from photogeologic mapping. The dominance of VLT basalt among lunar meteorites contrasts with its scarcity among Apollo samples. The resolution of these discrepancies awaits further studies of basaltic lunar meteorites and further discoveries of new lunar meteorites

Distribution of siderophile and other trace elements in melt rock at the Chicxulub impact structure

Recent isotopic and mineralogical studies have demonstrated a temporal and chemical link between the Chicxulub multiring impact basin and ejecta at the Cretaceous-Tertiary boundary. A fundamental problem yet to be resolved, however, is identification of the projectile responsible for this cataclysmic event. Drill core samples of impact melt rock from the Chichxulub structure contain Ir and Os abundances and Re-Os isotopic ratios indicating the presence of up to approx. 3 percent meteoritic material. We have used a technique involving microdrilling and high sensitivity instrumental neutron activation analysis (INAA) in conjunction with electron microprobe analysis to characterize further the distribution of siderophile and other trace elements among phases within the C1-N10 melt rock

Conifolds and Geometric Transitions

Conifold geometries have recieved a lot of attention in string theory and string-inspired cosmology recently, in particular the Klebanov-Strassler background that is known as the "warped throat". It is our intention in this article to give a pedagogical explanation for the singularity resolution in this geometry and emphasise its connection to geometric transitions. The first part focuses on the gauge theory dual to the Klebanov-Strassler background, which we also explain from a T-dual intersecting branes scenario. We then make the connection to the Gopakumar-Vafa conjecture for open/closed string duality and summarise a series of papers verifying this model on the supergravity level. An appendix provides extensive background material about conifold geometries. We pay special attention to their complex structures and re-evaluate the supersymmetry conditions on the background flux in constructions with fractional D3-branes on the singular (Klebanov-Tseytlin) and resolved (Pando Zayas-Tseytlin) conifolds. We agree with earlier results that only the singular solution allows a supersymmetric flux, but point out the importance of using the correct complex structure to reach this conclusion.Comment: 37 pages, v3: accepted for publication in Reviews of Modern Physic

Fundamental Strings in Open String Theory at the Tachyonic Vacuum

We show that the world-volume theory on a D-p-brane at the tachyonic vacuum has solitonic string solutions whose dynamics is governed by the Nambu-Goto action of a string moving in (25+1) dimensional space-time. This provides strong evidence for the conjecture that at this vacuum the full (25+1) dimensional Poincare invariance is restored. We also use this result to argue that the open string field theory at the tachyonic vacuum must contain closed string excitations.Comment: LaTeX file, 16 pages, references and clarification adde

Development and validation of two self-reported tools for insulin resistance and hypertension risk assessment in a European cohort : the Feel4Diabetes-study

Early identification of type 2 diabetes mellitus (T2DM) and hypertension (HTN) risk may improve prevention and promote public health. Implementation of self-reported scores for risk assessment provides an alternative cost-effective tool. The study aimed to develop and validate two easy-to-apply screening tools identifying high-risk individuals for insulin resistance (IR) and HTN in a European cohort. Sociodemographic, lifestyle, anthropometric and clinical data obtained from 1581 and 1350 adults (baseline data from the Feel4Diabetes-study) were used for the European IR and the European HTN risk assessment index respectively. Body mass index, waist circumference, sex, age, breakfast consumption, alcohol, legumes and sugary drinks intake, physical activity and sedentary behavior were significantly correlated with Homeostatic Model Assessment of IR (HOMA-IR) and/or HTN and incorporated in the two models. For the IR index, the Area Under the Curve (AUC), sensitivity and specificity for identifying individuals above the 75th and 95th of HOMA-IR percentiles were 0.768 (95%CI: 0.721–0.815), 0.720 and 0.691 and 0.828 (95%CI: 0.766–0.890), 0.696 and 0.778 respectively. For the HTN index, the AUC, sensitivity and specificity were 0.778 (95%CI: 0.680–0.876), 0.667 and 0.797. The developed risk assessment tools are easy-to-apply, valid, and low-cost, identifying European adults at high risk for developing T2DM or having HTN

Additional experimental evidence for a solar influence on nuclear decay rates

Additional experimental evidence is presented in support of the recent hypothesis that a possible solar influence could explain fluctuations observed in the measured decay rates of some isotopes. These data were obtained during routine weekly calibrations of an instrument used for radiological safety at The Ohio State University Research Reactor using Cl-36. The detector system used was based on a Geiger-Mueller gas detector, which is a robust detector system with very low susceptibility to environmental changes. A clear annual variation is evident in the data, with a maximum relative count rate observed in January/February, and a minimum relative count rate observed in July/August, for seven successive years from July 2005 to June 2011. This annual variation is not likely to have arisen from changes in the detector surroundings, as we show here.Comment: 8 pages, 6 figure