1,068 research outputs found
Spin torque, tunnel-current spin polarization and magnetoresistance in MgO magnetic tunnel junctions
We examine the spin torque (ST) response of magnetic tunnel junctions (MTJs)
with ultra-thin MgO tunnel barrier layers to investigate the relationship
between the spin-transfer torque and the tunnel magnetoresistance (TMR) under
finite bias. We find that the spin torque per unit current exerted on the free
layer decreases by less than 10% over a bias range where the TMR decreases by
over 40%. We examine the implications of this result for various spin-polarized
tunneling models and find that it is consistent with magnetic-state-dependent
effective tunnel decay lengths.Comment: 4 pages, 3 figure
Development of integrated thermionic circuits for high-temperature applications
Integrated thermionic circuits (ITC) capable of extended operation in ambient temperatures up to 500 C are studied. A set of practical design and performance equations is demonstrated. Experimental results are discussed in which both devices and simple circuits were successfully operated in 5000 C environments for extended periods. It is suggested that ITC's may become an important technology for high temperature instrumentation and control systems in geothermal and other high temperature environments
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Characterization of the inflammatory response to four commercial bone graft substitutes using a murine biocompatibility model
Bone grafting is utilized in nearly all orthopedic subspecialties and in most anatomic regions. Bone graft substitutes have the potential to offer similar efficacy as autogenous grafts without the morbidity of harvest. Several studies have noted the efficacy of new-generation bone substitute products, but few studies have evaluated their safety. This study characterizes and quantifies the inflammatory reaction to four different commercially available bone graft substitutes, which were examined using the in vivo murine air pouch biocompatibility model. One coralline hydroxyapatite product was chosen as an example of a purely osteoconductive material. Three demineralized bone matrix products were chosen to represent products that are both osteoconductive and osteoinductive. Samples were implanted in a murine air pouch and harvested after 14 days in situ. Pouch fluid was extracted, mRNA isolated, and reverse transcription polymerase chain reactions carried out to detect interleukin-1 gene expression as a marker for inflammation. In addition, multiple histological characteristics were examined to quantify cellular responses to the implanted materials. All bone graft substitutes induced a significant inflammatory response compared with negative controls. Histology and polymerase chain reaction data indicated that the level of inflammatory reaction was elevated in materials with a higher demineralized bone matrix to carrier proportion. The hydroxyapatite product generated a low inflammatory reaction. In conclusion, this study used an in vivo model of biocompatibility to demonstrate that a significant inflammatory reaction occurs when using implanted bone graft substitutes. When choosing a bone grafting method, surgeons should consider both the efficacy and safety of methods and materials used. Further studies are necessary to determine the ideal bone graft material to maximize efficacy while minimizing morbidity
TOPSAN: a dynamic web database for structural genomics
The Open Protein Structure Annotation Network (TOPSAN) is a web-based collaboration platform for exploring and annotating structures determined by structural genomics efforts. Characterization of those structures presents a challenge since the majority of the proteins themselves have not yet been characterized. Responding to this challenge, the TOPSAN platform facilitates collaborative annotation and investigation via a user-friendly web-based interface pre-populated with automatically generated information. Semantic web technologies expand and enrich TOPSAN’s content through links to larger sets of related databases, and thus, enable data integration from disparate sources and data mining via conventional query languages. TOPSAN can be found at http://www.topsan.org
Living with AMD treatment: Patient experiences of being treated with Ranibizumab (Lucentis) intravitreal injections
This study reports the results of a qualitative study of patient experiences of receiving treatment for wet age-related macular degeneration with ranibizumab (Lucentis)(R). Treatment involved monthly hospital visits for assessment and, where required, an intravitreal Lucentis injection. Qualitative narrative interviews were conducted with 22 patients, 18 of whom received treatment and were interviewed at two points during their treatment journey. Interviews allowed participants to reflect on their experiences of being assessed for and receiving this treatment. Overall, treated participants reported that while they had been apprehensive about treatment, the actual experience of it was far less unpleasant than they had expected. However, the data also revealed a number of issues surrounding the provision of information about treatment, as well as service delivery issues, which had considerable impact upon their experience
Structure of the first representative of Pfam family PF04016 (DUF364) reveals enolase and Rossmann-like folds that combine to form a unique active site with a possible role in heavy-metal chelation.
The crystal structure of Dhaf4260 from Desulfitobacterium hafniense DCB-2 was determined by single-wavelength anomalous diffraction (SAD) to a resolution of 2.01 Å using the semi-automated high-throughput pipeline of the Joint Center for Structural Genomics (JCSG) as part of the NIGMS Protein Structure Initiative (PSI). This protein structure is the first representative of the PF04016 (DUF364) Pfam family and reveals a novel combination of two well known domains (an enolase N-terminal-like fold followed by a Rossmann-like domain). Structural and bioinformatic analyses reveal partial similarities to Rossmann-like methyltransferases, with residues from the enolase-like fold combining to form a unique active site that is likely to be involved in the condensation or hydrolysis of molecules implicated in the synthesis of flavins, pterins or other siderophores. The genome context of Dhaf4260 and homologs additionally supports a role in heavy-metal chelation
Simultaneous genome sequencing of symbionts and their hosts
Second-generation sequencing has made possible the sequencing of genomes of interest for even small research groups. However, obtaining separate clean cultures and clonal or inbred samples of metazoan hosts and their bacterial symbionts is often difficult. We present a computational pipeline for separating metazoan and bacterial DNA in silico rather than at the bench. The method relies on the generation of deep coverage of all the genomes in a mixed sample using Illumina short-read sequencing technology, and using aggregate properties of the different genomes to identify read sets belonging to each. This inexpensive and rapid approach has been used to sequence several nematode genomes and their bacterial endosymbionts in the last year in our laboratory and can also be used to visualize and identify unexpected contaminants (or possible symbionts) in genomic DNA samples. We hope that this method will enable researchers studying symbiotic systems to move from gene-centric to genome-centric approaches
First LIGO search for gravitational wave bursts from cosmic (super)strings
We report on a matched-filter search for gravitational wave bursts from
cosmic string cusps using LIGO data from the fourth science run (S4) which took
place in February and March 2005. No gravitational waves were detected in 14.9
days of data from times when all three LIGO detectors were operating. We
interpret the result in terms of a frequentist upper limit on the rate of
gravitational wave bursts and use the limits on the rate to constrain the
parameter space (string tension, reconnection probability, and loop sizes) of
cosmic string models.Comment: 11 pages, 3 figures. Replaced with version submitted to PR
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