Aerospace applications of high temperature superconductivity

Space application of high temperature superconducting (HTS) materials may occur before most terrestrial applications because of the passive cooling possibilities in space and because of the economic feasibility of introducing an expensive new technology which has a significant system benefit in space. NASA Lewis Research Center has an ongoing program to develop space technology capitalizing on the potential benefit of HTS materials. The applications being pursued include space communications, power and propulsion systems, and magnetic bearings. In addition, NASA Lewis is pursuing materials research to improve the performance of HTS materials for space applications

Investigations into the Sarcomeric Protein and Ca2+-Regulation Abnormalities Underlying Hypertrophic Cardiomyopathy in Cats (Felix catus).

Hypertrophic cardiomyopathy (HCM) is the most common single gene inherited cardiomyopathy. In cats (Felix catus) HCM is even more prevalent and affects 16% of the outbred population and up to 26% in pedigree breeds such as Maine Coon and Ragdoll. Homozygous MYBPC3 mutations have been identified in these breeds but the mutations in other cats are unknown. At the clinical and physiological level feline HCM is closely analogous to human HCM but little is known about the primary causative mechanism. Most identified HCM causing mutations are in the genes coding for proteins of the sarcomere. We therefore investigated contractile and regulatory proteins in left ventricular tissue from 25 cats, 18 diagnosed with HCM, including a Ragdoll cat with a homozygous MYBPC3 R820W, and 7 non-HCM cats in comparison with human HCM (from septal myectomy) and donor heart tissue. Myofibrillar protein expression was normal except that we observed 20–44% MyBP-C haploinsufficiency in 5 of the HCM cats. Troponin extracted from 8 HCM and 5 non-HCM cat hearts was incorporated into thin filaments and studied by in vitro motility assay. All HCM cat hearts had a higher (2.06 ± 0.13 fold) Ca2+-sensitivity than non-HCM cats and, in all the HCM cats, Ca2+-sensitivity was not modulated by troponin I phosphorylation. We were able to restore modulation of Ca2+-sensitivity by replacing troponin T with wild-type protein or by adding 100 μM Epigallocatechin 3-gallate (EGCG). These fundamental regulatory characteristics closely mimic those seen in human HCM indicating a common molecular mechanism that is independent of the causative mutation. Thus, the HCM cat is a potentially useful large animal model

Study of railway track stiffness modification by polyurethane reinforcement of the ballast

This paper presents the measured results of full-scale testing of railway track under laboratory conditions to examine the effect on the track stiffness when the ballast is reinforced using a urethane cross-linked polymer (polyurethane). The tests are performed in the GRAFT I (Geopavement and Railways Accelerated Fatigue Testing) facility and show that the track stiffness can be significantly enhanced by application of the polymer. The track stiffness is measured at various stages during cyclic loading and compared to the formation stiffness, which is determined prior to testing using plate load tests. The results indicate that the track stiffness increased by approximately 40–50% based on the measured results and from the previously published GRAFT I settlement model. The track stiffness was monitored during loading for a maximum of 500,000 load cycles. The paper concludes by presenting and commenting on, the application of the technique to a real site where the Falling Weight Deflectometer was used before and after polymer treatment to determine the dynamic sleeper support stiffness. The very challenging site conditions are highlighted, in particular the water logged nature of the site, and comment made on the effect of the water on polymer installation. The results of the FWD measurements indicate that a good increase in overall track stiffness was measured. These results are consistent with the laboratory tests which are performed on a different soil and use a different measurement technique and hence confirm that regardless of the soil and measurement system track stiffness increases are observed using this technique

NASA Space applications of high-temperature superconductors

The application of superconducting technology in space has been limited by the requirement of cooling to near liquid helium temperatures. The only means of obtaining these temperatures has been with cryogenic fluids which severely limit mission lifetime. The development of materials with superconducting transition temperatures above 77 K has made superconducting technology more attractive and feasible for employment in aerospace systems. Here, potential applications of high temperature superconducting technology in cryocoolers, remote sensing, communications, and power systems are discussed

Stromgren Photometry from z=0 to z~1. The Method

We use rest-frame Stromgren photometry to observe clusters of galaxies in a self-consistent manner from z=0 to z=0.8. Stromgren photometry of galaxies is an efficient compromise between standard broad-band photometry and spectroscopy, in the sense that it is more sensitive to subtle variations in spectral energy distributions than the former, yet much less time-consuming than the latter. Principal Component Analysis (PCA) is used to extract maximum information from the Stromgren data. By calibrating the Principal Components using well-studied galaxies (and stellar population models), we develop a purely empirical method to detect, and subsequently classify, cluster galaxies at all redshifts smaller than 0.8. Interlopers are discarded with unprecedented efficiency (up to 100%). The first Principal Component essentially reproduces the Hubble Sequence, and can thus be used to determine the global star formation history of cluster members. The (PC2, PC3) plane allows us to identify Seyfert galaxies (and distinguish them from starbursts) based on photometric colors alone. In the case of E/S0 galaxies with known redshift, we are able to resolve the age-dust- metallicity degeneracy, albeit at the accuracy limit of our present observations. This technique will allow us to probe galaxy clusters well beyond their cores and to fainter magnitudes than spectroscopy can achieve. We are able to directly compare these data over the entire redshift range without a priori assumptions because our observations do not require k-corrections. The compilation of such data for different cluster types over a wide redshift range is likely to set important constraints on the evolution of galaxies and on the clustering process.Comment: 35 pages, 18 figures, accepted by ApJ

Coral adaptation to climate change: meta-analysis reveals high heritability across multiple traits

Anthropogenic climate change is a rapidly intensifying selection pressure on biodiversity across the globe and, particularly, on the world's coral reefs. The rate of adaptation to climate change is proportional to the amount of phenotypic variation that can be inherited by subsequent generations (i.e., narrow-sense heritability, h2). Thus, traits that have higher heritability (e.g., h2 > 0.5) are likely to adapt to future conditions faster than traits with lower heritability (e.g., h2 0.50) for metrics related to survival and immune responses. Some of these values are higher than typically observed in other taxa, such as survival and growth, while others were more comparable, such as gene expression and photochemistry. There was no detectable effect of temperature on heritability, but narrow-sense heritability estimates were generally lower than broad-sense estimates, indicative of significant non-additive genetic variation across traits. Trait heritability also varied depending on coral life stage, with bleaching and growth in juveniles generally having lower heritability compared to bleaching and growth in larvae and adults. These differences may be the result of previous stabilizing selection on juveniles or may be due to constrained evolution resulting from genetic trade-offs or genetic correlations between growth and thermotolerance. While we find no evidence that heritability decreases under temperature stress, explicit tests of the heritability of thermal tolerance itself—such as coral thermal reaction norm shape—are lacking. Nevertheless, our findings overall reveal high trait heritability for the majority of coral traits, suggesting corals may have a greater potential to adapt to climate change than has been assumed in recent evolutionary models

Patient experiences of a physiotherapy-led multidisciplinary rehabilitative intervention after successful treatment for oesophago-gastric cancer

Purpose To qualitatively explore the perceived impact of a 12-week rehabilitative intervention for oesophago-gastric cancer survivors on their physical, mental and social wellbeing. Methods Of the 21 participants who completed the intervention, 19 took part in a semi-structured focus group interview. Four audio-taped focus groups were held, ranging in size from two to eight participants. Focus groups were transcribed and analysed using a descriptive qualitative approach. Results At recruitment, participants were 23.5 ± 15.2 months post-surgery and all had suboptimal fitness levels. Participants reported improvements in their physical capacity and ability to carry out activities of daily living during the intervention. These improvements led to increased confidence and social connectivity. Other participants were a valuable source of information and reassurance, while support from family members was variable. Future interventions should educate participants on how to maintain gains achieved during the intervention. Conclusions Participating in an exercise-based multidisciplinary rehabilitative intervention reduces isolation and helps oesophago-gastric cancer survivors to safely negotiate their physical, emotional and social needs as they move further down the path of recovery

Ventricular endocardial tissue geometry affects stimulus threshold and effective refractory period

Background: Understanding the biophysical processes by which electrical stimuli applied to cardiac tissue may result in local activation is important in both the experimental and clinical electrophysiology laboratory environments, as well as for gaining a more in-depth knowledge of the mechanisms of focal-trigger-induced arrhythmias. Previous computational models have predicted that local myocardial tissue architecture alone may significantly modulate tissue excitability, affecting both the local stimulus current required to excite the tissue and the local effective refractory period (ERP). In this work, we present experimental validation of this structural modulation of local tissue excitability on the endocardial tissue surface, use computational models to provide mechanistic understanding of this phenomena in relation to localized changes in electrotonic loading, and demonstrate its implications for the capture of afterdepolarizations. Methods and Results: Experiments on rabbit ventricular wedge preparations showed that endocardial ridges (surfaces of negative mean curvature) had a stimulus capture threshold that was 0.21 ± 0.03 V less than endocardial grooves (surfaces of positive mean curvature) for pairwise comparison (24% reduction, corresponding to 56.2 ± 6.4% of the energy). When stimulated at the minimal stimulus strength for capture, ridge locations showed a shorter ERP than grooves (n = 6, mean pairwise difference 7.4 ± 4.2 ms). When each site was stimulated with identical-strength stimuli, the difference in ERP was further increased (mean pairwise difference 15.8 ± 5.3 ms). Computational bidomain models of highly idealized cylindrical endocardial structures qualitatively agreed with these findings, showing that such changes in excitability are driven by structural modulation in electrotonic loading, quantifying this relationship as a function of surface curvature. Simulations further showed that capture of delayed afterdepolarizations was more likely in trabecular ridges than grooves, driven by this difference in loading. Conclusions: We have demonstrated experimentally and explained mechanistically in computer simulations that the ability to capture tissue on the endocardial surface depends upon the local tissue architecture. These findings have important implications for deepening our understanding of excitability differences related to anatomical structure during stimulus application that may have important applications in the translation of novel experimental optogenetics pacing strategies. The uncovered preferential vulnerability to capture of afterdepolarizations of endocardial ridges, compared to grooves, provides important insight for understanding the mechanisms of focal-trigger-induced arrhythmias

Phase stability analysis in Fe-Pt and Co-Pt alloy systems: An augmented space study

We have studied the problem of phase stability in Fe-Pt and Co-Pt alloy systems. We have used the orbital peeling technique in the conjunction of augmented space recursion based on the tight binding linear orbital method as the method for the calculation of pair interaction energies. In particular, we have generalized our earlier technique to take into account of magnetic effects for the cases where the magnetic transition is higher than the order disorder chemical transition temperature as in the case of Co$_3$Pt. Our theoretical results obtained within this framework successfully reproduce the experimentally observed trends.Comment: 17 pages, 9 Figures. Accepted for publication in Journal of Physics : Condensed Matte