3,445 research outputs found
On-orbit cryogenic fluid transfer
A number of future NASA and DOD missions have been identified that will require, or could benefit from resupply of cryogenic liquids in orbit. The most promising approach for accomplishing cryogenic fluid transfer in the weightlessness environment of space is to use the thermodynamic filling technique. This approach involves initially reducing the receiver tank temperature by using several charge hold vent cycles followed by filling the tank without venting. Martin Marietta Denver Aerospace, under contract to the NASA Lewis Research Center, is currently developing analytical models to describe the on orbit cryogenic fluid transfer process. A detailed design of a shuttle attached experimental facility, which will provide the data necessary to verify the analytical models, is also being performed
Focused cardiac ultrasound examination in the emergency and critical care horse: Training for non‐specialist veterinarians and evaluation of proficiency
Background: Focused cardiac ultrasound examination (FoCUS) is rapidly emerging for point-of-care cardiac assessment using hand-carried ultrasound (HCU) devices. A specific FoCUS protocol for horses and adequate training guidelines currently are not available.
Hypothesis: To gain knowledge about the training necessary to become proficient in performing FoCUS using a HCU device.
Animals: Three healthy Warmblood horses were used for practical training of veterinarians and veterinary students in equine focused cardiac ultrasound (eFoCUS).
Methods: Prospective educational study. An eFoCUS protocol and 1-day training course were developed. Pre- and post-course written tests were administered to participants to evaluate proficiency in knowledge of echocardiography and echocardiographic pathology. A post-course practical examination involved performing eFoCUS and storage of representative images. Images were evaluated using an image quality score and compared between participants with some practical experience and participants with no practical experience.
Results: Participants' knowledge of echocardiography increased significantly. Recognition of echocardiographic pathology pre-course ranged from 40% to 90% (mean score, 65.7%) and post-course from 85% to 100% (mean score, 92%). Eighteen of 21 participants were proficient in performing eFoCUS with a median image quality score of 79% (range, 42%-95%). Image quality did not differ between participants with some practical experience compared to participants with no experience.
Conclusions and clinical importance: Veterinarians and veterinary students independent of previous experience can become proficient in performing eFoCUS after completion of a 1-day training course
Structural genomics analysis of uncharacterized protein families overrepresented in human gut bacteria identifies a novel glycoside hydrolase.
BackgroundBacteroides spp. form a significant part of our gut microbiome and are well known for optimized metabolism of diverse polysaccharides. Initial analysis of the archetypal Bacteroides thetaiotaomicron genome identified 172 glycosyl hydrolases and a large number of uncharacterized proteins associated with polysaccharide metabolism.ResultsBT_1012 from Bacteroides thetaiotaomicron VPI-5482 is a protein of unknown function and a member of a large protein family consisting entirely of uncharacterized proteins. Initial sequence analysis predicted that this protein has two domains, one on the N- and one on the C-terminal. A PSI-BLAST search found over 150 full length and over 90 half size homologs consisting only of the N-terminal domain. The experimentally determined three-dimensional structure of the BT_1012 protein confirms its two-domain architecture and structural analysis of both domains suggests their specific functions. The N-terminal domain is a putative catalytic domain with significant similarity to known glycoside hydrolases, the C-terminal domain has a beta-sandwich fold typically found in C-terminal domains of other glycosyl hydrolases, however these domains are typically involved in substrate binding. We describe the structure of the BT_1012 protein and discuss its sequence-structure relationship and their possible functional implications.ConclusionsStructural and sequence analyses of the BT_1012 protein identifies it as a glycosyl hydrolase, expanding an already impressive catalog of enzymes involved in polysaccharide metabolism in Bacteroides spp. Based on this we have renamed the Pfam families representing the two domains found in the BT_1012 protein, PF13204 and PF12904, as putative glycoside hydrolase and glycoside hydrolase-associated C-terminal domain respectively
Data for Change: A Statistical Analysis of Police Stops, Searches, Handcuffings, and Arrests in Oakland, Calif., 2013-2014
Law enforcement agencies across the United States are facing claims that they discriminate against community members of color. Inquiries into these claims typically take one of two approaches: either attack the agency for intentional racism, or deny the presence of racial disparities altogether. Yet neither of these approaches has yielded adequate progress toward many agencies' stated mission of serving their communities with fairness and respect. Taking a different approach, the City of Oakland engaged our team of Stanford social psychologists to examine relations between the Oakland Police Department (OPD) and the Oakland community, and then to develop evidence-based remedies for any racial disparities we might find. Since May 2014, our team has undertaken five research initiatives. We describe our research methods, findings, and recommendations in Strategies for Change: Research Initiatives and Recommendations to Improve Police-Community Relations in Oakland, Calif. We provide a technical report of our main research initiative, a thorough analysis of OPD stop reports, in Data for Change: A Statistical Analysis of Police Stops, Searches, Handcuffings, and Arrests in Oakland, Calif., 2013-2014
New Hampshire Volunteer Beach Profile Monitoring Program (VBPMP): Implementation, Field Methods, and Data Processing
The New Hampshire (NH) Volunteer Beach Profiling Monitoring Program (VBPMP) monitors beach elevation profiles at multiple stations along the NH Atlantic coast on a near-monthly basis using the Emery method. The program grew from three monitoring stations in 2016-2017 to thirteen stations across six beaches in 2018, with an additional station added in 2022. The overarching goal of the VBPMP is to assess the stability of New Hampshire’s Atlantic beaches over multiple years to determine seasonal changes and long-term trends using citizen science methods. Included in the assessment of beach stability are erosional or accretional trends, response to storms, and comparisons between beaches with differing morphology, sediments, and infrastructure (e.g., seawalls or dunes). Presented in this report are the methods used by the NH VBPMP for establishing profile stations, collecting beach elevation profiles based on the Emery method, recording, and uploading field data, and taking field photographs. The methods used for processing profile data after collection by volunteers is also described, including data review and quality assurance, datum corrections, plotting elevation profiles, sediment volume computation, and determination of mean profile elevations. Finally, examples of data products created for sharing with the public are presented
Passive Retention/Expulsion Methods for Subcritical Storage of Cryogens
Development of passive retention/expulsion system for subcritical storage of cryogenic material during low gravity situation
Bisphenol A Binds to the Local Anesthetic Receptor Site to Block the Human Cardiac Sodium Channel
Bisphenol A (BPA) has attracted considerable public attention as it leaches from plastic used in food containers, is detectable in human fluids and recent epidemiologic studies link BPA exposure with diseases including cardiovascular disorders. As heart-toxicity may derive from modified cardiac electrophysiology, we investigated the interaction between BPA and hNav1.5, the predominant voltage-gated sodium channel subtype expressed in the human heart. Electrophysiology studies of heterologously-expressed hNav1.5 determined that BPA blocks the channel with a Kd of 25.4±1.3 µM. By comparing the effects of BPA and the local anesthetic mexiletine on wild type hNav1.5 and the F1760A mutant, we demonstrate that both compounds share an overlapping binding site. With a key binding determinant thus identified, an homology model of hNav1.5 was generated based on the recently-reported crystal structure of the bacterial voltage-gated sodium channel NavAb. Docking predictions position both ligands in a cavity delimited by F1760 and contiguous with the DIII–IV pore fenestration. Steered molecular dynamics simulations used to assess routes of ligand ingress indicate that the DIII–IV pore fenestration is a viable access pathway. Therefore BPA block of the human heart sodium channel involves the local anesthetic receptor and both BPA and mexiletine may enter the closed-state pore via membrane-located side fenestrations
LUD, a new protein domain associated with lactate utilization.
BackgroundA novel highly conserved protein domain, DUF162 [Pfam: PF02589], can be mapped to two proteins: LutB and LutC. Both proteins are encoded by a highly conserved LutABC operon, which has been implicated in lactate utilization in bacteria. Based on our analysis of its sequence, structure, and recent experimental evidence reported by other groups, we hereby redefine DUF162 as the LUD domain family.ResultsJCSG solved the first crystal structure [PDB:2G40] from the LUD domain family: LutC protein, encoded by ORF DR_1909, of Deinococcus radiodurans. LutC shares features with domains in the functionally diverse ISOCOT superfamily. We have observed that the LUD domain has an increased abundance in the human gut microbiome.ConclusionsWe propose a model for the substrate and cofactor binding and regulation in LUD domain. The significance of LUD-containing proteins in the human gut microbiome, and the implication of lactate metabolism in the radiation-resistance of Deinococcus radiodurans are discussed
Magnetism and interlayer coupling in fcc Fe/Co films
The magnetism of epitaxial fee Fe films deposited on Co(100) and sandwiched between two Co(100) films was investigated by x-ray magnetic circular dichroism. The dependence of the Fe magnetism on the film thickness is complex and qualitatively similar on Co(100) and in fee Co/Fe/Co(100) trilayers. The fee Fe film magnetization presents a pronounced oscillation, suggesting a partial antiferromagnetic ordering in the 5-10 monolayer thickness range. The fee Fe films mediate an oscillatory, indirect coupling in Co/Fe/Co(100) structures that alternates in correspondence with the changes of the Fe magnetization
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