Carbon thin film thermometry

The work concerning carbon thin film thermometry is reported. Optimum film deposition parameters were sought on an empirical basis for maximum stability of the films. One hundred films were fabricated for use at the Marshall Space Flight Center; 10 of these films were given a precise quasi-continuous calibration of temperature vs. resistance with 22 intervals between 5 and 80 K using primary platinum and germanium thermometers. Sensitivity curves were established and the remaining 90 films were given a three point calibration and fitted to the established sensitivity curves. Hydrogen gas-liquid discrimination set points are given for each film

A Study of the Effect of Blended Coarse Aggregate on Air Entrained Concrete

This research with combined coarse aggregates in cement concrete was initiated at the request of the Director of Design as a direct result of the condition study made by the Division of Design in 1945. In the report on this study it was shown that on the basis of averages pertaining to 80 projects with crashed limestone totalling about 395 miles in length, and 70 projects with Ohio River Gravel totalling approximately 410 miles in length, the service record for pavements with the river gravel was far inferior to that of pavements containing limestone coarse aggregate. Specifically, the summary of data showed that pavements with the gravel had an average of seven times as many outside corner breaks, more than eight times as many inside corner breaks, and almost eleven times as many blow-ups per mile as the pavements with crushed lime stone; furthermore, the average transverse crack and joint interval in the former was only about 0. 6 as long as that in the latter. Such rating was irrespective of age, design, subgrade conditions, separate sources of aggregates, and other factors which in the total analysis were considered individually but which could not be isolated as influences in combination with the coarse aggregates. Naturally, the effect of one or all of these factors could reduce the disparity in performance as related to aggregates alone, nevertheless, the contrast was so pronounced that some measures for obtaining parity of concrete with the different aggregates were considered desirable. As an absolute minimum, research to determine whether results of field observations would be reflected in laboratory tests was proposed. Accordingly, this project was established through an outline or working plan prepared on May 18, 1946. Two corrective measures, air entrainment and blending of aggregates, were the primary bases upon which the research was founded. Results from many investigations - later summarized in a comprehensive report - had indicated that air entrainment had been beneficial to concrete in almost every experiment, and that the greatest improvement in quality of concrete had occurred when the coarse aggregates were inherently of lowest quality. Similarly, blending of aggregates as a means for off-setting detrimental properties of one of the components had been used successfully in other states, an outstanding example of this being in Kansas where aggregates are quite variable and satisfactory sources are far from evenly distributed throughout the state. (A copy of the Supplemental Specification developed in Kansas is appended to this report.) Since air entrainment was due to become a. standard in concrete for pavements, interest was centered on the possible benefits or detriments of combined aggregates and the proportions in which they should be combined in order to provide the best concrete within practicable limits of economy on actual construction jobs

Study of the Effect of Blended Coarse Aggregate on Air Entrained Concrete

This research with combined coarse aggregates in cement concrete was initiated at the request of the Director of Design as a direct result of the condition study made by the Division of Design in 1945. In the report on this study it was shown that on the basis of averages pertaining to 80 projects with crushed limestone totalling about 395 miles in length, and 70 projects with Ohio River Gravel totalling approximately 410 miles in length, the service record for pavements with the river gravel was far inferior to that of pavements containing limestone coarse aggregate. Specifically, the summary of data showed that pavements with the gravel had an average of seven times as many outside corner breaks, more than eight times as many inside corner breaks, and almost elevent time sas many blow-ups per mile as the pavements with crushed limestone; furthermore, the average transverse crack and joint interval in the former was only about 0.6 as long as that in the latter

Magnetic Structure of Rapidly Rotating FK Comae-Type Coronae

We present a three-dimensional simulation of the corona of an FK Com-type rapidly rotating G giant using a magnetohydrodynamic model that was originally developed for the solar corona in order to capture the more realistic, non-potential coronal structure. We drive the simulation with surface maps for the radial magnetic field obtained from a stellar dynamo model of the FK Com system. This enables us to obtain the coronal structure for different field topologies representing different periods of time. We find that the corona of such an FK Com-like star, including the large scale coronal loops, is dominated by a strong toroidal component of the magnetic field. This is a result of part of the field being dragged by the radial outflow, while the other part remains attached to the rapidly rotating stellar surface. This tangling of the magnetic field,in addition to a reduction in the radial flow component, leads to a flattening of the gas density profile with distance in the inner part of the corona. The three-dimensional simulation provides a global view of the coronal structure. Some aspects of the results, such as the toroidal wrapping of the magnetic field, should also be applicable to coronae on fast rotators in general, which our study shows can be considerably different from the well-studied and well-observed solar corona. Studying the global structure of such coronae should also lead to a better understanding of their related stellar processes, such as flares and coronal mass ejections, and in particular, should lead to an improved understanding of mass and angular momentum loss from such systems.Comment: Accepted to ApJ, 10 pages, 6 figure

Instrumentation for hydrogen slush storage containers

Hydrogen liquid and slush tank continuous inventory during ground storag

Preferential sites for intramolecular glucosepane cross-link formation in type I collagen: A thermodynamic study

The extracellular matrix (ECM) undergoes progressive age-related stiffening and loss of proteolytic digestibility due to an increase in concentration of advanced glycation end products (AGEs). The most abundant AGE, glucosepane, accumulates in collagen with concentrations over 100 times greater than all other AGEs. Detrimental collagen stiffening properties are believed to play a significant role in several age-related diseases such as osteoporosis and cardiovascular disease. Currently little is known of the potential location of covalently cross-linked glucosepane formation within collagen molecules; neither are there reports on how the respective cross-link sites affect the physical and biochemical properties of collagen. Using fully atomistic molecular dynamics simulations (MD) we have identified six sites where the formation of a covalent intra-molecular glucosepane cross-link within a single collagen molecule in a fibrillar environment is energetically favourable. Identification of these favourable sites enables us to align collagen cross-linking with experimentally observed changes to the ECM. For example, formation of glucosepane was found to be energetically favourable within close proximity of the Matrix Metalloproteinase-1 (MMP1) binding site, which could potentially disrupt collagen degradation.fals

On the Effect of Magnetic Spots on Stellar Winds and Angular Momentum Loss

We simulate the effect of latitudinal variations in the location of star spots, as well as their magnetic field strength, on stellar angular momentum loss to the stellar wind. We use the Michigan solar corona global MagnetoHydroDynamic model, which incorporates realistic relation between the magnetic field topology and the wind distribution. We find that the spots location significantly affects the stellar wind structure, and as a result, the total mass loss rate and angular momentum loss rate. In particular, we find that the angular momentum loss rate is controlled by the mass flux when spots are located at low latitudes but is controlled by an increased plasma density between the stellar surface and the Alfven surface when spots are located at high latitudes. Our results suggest that there might be a feedback mechanism between the magnetic field distribution, wind distribution, angular momentum loss through the wind, and the motions at the convection zone that generate the magnetic field. This feedback might explain the role of coronal magnetic fields in stellar dynamos

The first WASP public data release

The WASP (wide angle search for planets) project is an exoplanet transit survey that has been automatically taking wide field images since 2004. Two instruments, one in La Palma and the other in South Africa, continually monitor the night sky, building up light curves of millions of unique objects. These light curves are used to search for the characteristics of exoplanetary transits. This first public data release (DR1) of the WASP archive makes available all the light curve data and images from 2004 up to 2008 in both the Northern and Southern hemispheres. A web interface () to the data allows easy access over the Internet. The data set contains 3 631 972 raw images and 17 970 937 light curves. In total the light curves have 119 930 299 362 data points available between them

Force-Free Models of Magnetically Linked Star-Disk Systems

Disk accretion onto a magnetized star occurs in a variety of astrophysical contexts, from young stars to X-ray pulsars. The magnetohydrodynamic interaction between the stellar field and the accreting matter can have a strong effect on the disk structure, the transfer of mass and angular momentum between the disk and the star, and the production of bipolar outflows, e.g., plasma jets. We study a key element of this interaction - the time evolution of the magnetic field configuration brought about by the relative rotation between the disk and the star - using simplified, largely semianalytic, models. We first discuss the rapid inflation and opening up of the magnetic field lines in the corona above the accretion disk, which is caused by the differential rotation twisting. Then we consider additional physical effects that tend to limit this expansion, such as the effect of plasma inertia and the possibility of reconnection in the disk's corona, the latter possibly leading to repeated cycles in the evolution. We also derive the condition for the existence of a steady state for a resistive disk and conclude that a steady state configuration is not realistically possible. Finally, we generalize our analysis of the opening of magnetic field lines by using a non-self-similar numerical model that applies to an arbitrarily rotating (e.g. keplerian) disk.Comment: 75 pages, 22 figures, 2 tables. Submitted to Astrophysical Journa