389 research outputs found

    XTE J2123-058: A New Neutron Star X-Ray Transient

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    We report on optical and RXTE observations of a new high-latitude bursting X-ray transient, XTE J2123-058. We identified the optical counterpart, measured the 5.9573 hr orbital period and constrained the binary inclination and the source distance. The distance lower limit indicates that the source is at least 2.6 kpc from the Galactic plane, which is unusual for an LMXB. RXTE observations were made between June and August 1998 during the first detected outburst from this source. We describe correlations between X-ray timing and spectral properties and discuss the possibility that the propeller mechanism turned on during the decay of the outburst. During one of the RXTE observations, we detect a pair of high frequency QPOs at 847.1 +/- 5.5 Hz and 1102 +/- 13 Hz simultaneously. According to the beat frequency model, the QPO separation implies a neutron star spin period near 3.9 ms. As the X-ray flux decreases at the end of the outburst, the amplitude of the optical modulation increases significantly. This behavior can be explained if the size of the accretion disk decreases during the decay of the outburst.Comment: 24 pages, 9 figures, accepted by Ap

    Autoantigens in Vitiligo Identified by the Serological Selection of a Phage-Displayed Melanocyte cDNA Expression Library

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    Vitiligo is an acquired idiopathic hypomelanotic disorder characterized by circumscribed depigmented macules resulting from the loss of cutaneous melanocytes. Although the exact cause of vitiligo remains obscure, autoimmunity may play a role in the development of the disease. The present study was undertaken to investigate the applicability of phage display technology to identify B-cell autoantigens in vitiligo. A melanocyte cDNA phage display library was subjected to rounds of enrichment with vitiligo patient IgG. Subsequently, enriched IgG-binding peptides representing putative autoantigens were identified by sequencing their encoding cDNAs. Radioimmunoassays were used to confirm the immunoreactivity of vitiligo patient (n=61) and control (n=28) sera to several of the putative autoantigens. Non-segmental vitiligo patient sera (n=53) were positive for antibody (Ab) reactivity to gamma-enolase (8%); alpha-enolase (9%); heat-shock protein 90 (13%); osteopontin (4%); ubiquitin-conjugating enzyme (15%); translation-initiation factor 2 (6%); and GTP-binding protein, Rab38 (15%). Ab reactivity to at least one of the previously unknown autoantigens was detected in 51% of patients with non-segmental vitiligo. In contrast, Ab reactivity in a group of patients with segmental vitiligo (n=8) was not demonstrated. Overall, the study indicated that the targets of autoantibodies in vitiligo patients can be revealed by employing the methodology of phage display

    The future of upper extremity rehabilitation robotics: research and practice

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    The loss of upper limb motor function can have a devastating effect on people’s lives. To restore upper limb control and functionality, researchers and clinicians have developed interfaces to interact directly with the human body’s motor system. In this invited review, we aim to provide details on the peripheral nerve interfaces and brain‐machine interfaces that have been developed in the past 30 years for upper extremity control, and we highlight the challenges that still remain to transition the technology into the clinical market. The findings show that peripheral nerve interfaces and brain‐machine interfaces have many similar characteristics that enable them to be concurrently developed. Decoding neural information from both interfaces may lead to novel physiological models that may one day fully restore upper limb motor function for a growing patient population.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155489/1/mus26860_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155489/2/mus26860.pd

    Stimulated grip strength measurement: Validation of a novel method for functional assessment

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    BackgroundReliable measurement of functional recovery is critical in translational peripheral nerve regeneration research. Behavioral functional assessments such as volitional grip strength testing (vGST) are limited by inherent behavioral variability. Isometric tetanic force testing (ITFT) is highly reliable but precludes serial measurements. Combining elements of vGST and ITFT, stimulated grip strength testing (sGST) involves percutaneous median nerve stimulation to elicit maximal tetanic contraction of digital flexors, thereby allowing for consistent measurement of maximal grip strength.MethodsWe measured side‐to‐side equivalence of force using sGST, vGST, and ITFT to determine relative reliability and repeatability. We also performed weekly force measurements following median nerve repair.ResultssGST demonstrated greater reliability and inter‐trial repeatability than vGST and similar reliability to ITFT, with the added benefit of serial measurements.ConclusionssGST is a valid method for assessing functional recovery that addresses the limitations of the currently available modalities used in translational peripheral nerve regeneration research.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151883/1/mus26646.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151883/2/mus26646_am.pd

    Relative Sea-Level Trends in New York City During the Past 1500 Years

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    New York City (NYC) is threatened by 21st-century relative sea-level (RSL) rise because it will experience a trend that exceeds the global mean and has high concentrations of low-lying infrastructure and socioeconomic activity. To provide a long-term context for anticipated trends, we reconstructed RSL change during the past ~1500 years using a core of salt-marsh sediment from Pelham Bay in The Bronx. Foraminifera and bulk-sediment δ13C values were used as sea-level indicators. The history of sediment accumulation was established by radiocarbon dating and recognition of pollution and land-use trends of known age in down-core elemental, isotopic, and pollen profiles. The reconstruction was generated within a Bayesian hierarchical model to accommodate multiple proxies and to provide a unified statistical framework for quantifying uncertainty. We show that RSL in NYC rose by ~1.70 m since ~575 CE (including ~0.38 m since 1850 CE). The rate of RSL rise increased markedly at 1812–1913 CE from ~1.0 to ~2.5 mm/yr, which coincides with other reconstructions along the US Atlantic coast. We investigated the possible influence of tidal-range change in Long Island Sound on our reconstruction using a regional tidal model, and we demonstrate that this effect was likely small. However, future tidal-range change could exacerbate the impacts of RSL rise in communities bordering Long Island Sound. The current rate of RSL rise is the fastest that NYC has experienced for \u3e1500 years, and its ongoing acceleration suggests that projections of 21st-century local RSL rise will be realized

    Archeological Testing and Data Recovery at 41ZV202, Zavala County, Texas

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    At the request of the Texas Department of Transportation, Environmental Affairs Division (TxDOT-ENV), the Center for Archaeological Research (CAR) of The University of Texas at San Antonio (UTSA) conducted archeological significance testing at 41ZV202, a prehistoric site located in northwestern Zavala County, in March of 2003. The work, conducted under Texas Antiquities Permit No. 3071 issued to Dr. Steven A. Tomka, was done in anticipation of the potential widening by TxDOT of FM 481. While materials dating to the Archaic were also present, the testing demonstrated the presence of significant Late Prehistoric (Austin Interval) deposits with good integrity within a portion of the TxDOT right-of-way (ROW). As TxDOT construction could not avoid these deposits, and as both the Texas Historical Commission (THC) and TxDOT concurred with CAR’s recommendations that the deposits were eligible for listing on the National Register of Historic Places (NRHP) under criterion d of 36CFR 60.4, data recovery investigations were initiated. CAR began that work in July and August of 2003. The testing permit was amended to include the data recovery efforts. Dr. Russell Greaves served as project archeologist for both the testing and data recovery effort at 41ZV202. The testing and data recovery work consisted of the excavation of a 53-m-long Gradall trench, exposing and profiling a 75-m-long road cut, and the hand excavation of 52 1 x 1 meter units that removed approximately 34.6 m3 of soil. Testing identified two large, dark stained areas designated Features 4 and 5, an associated hearth (Feature 7), and a small cluster of FCR (Feature 6). Just over 1,000 chipped stone items were recovered, including several Scallorn points, one reworked dart point, several bifaces, and two flake tools. Eleven AMS radiocarbon dates were submitted from deposits, with eight clustering around 1000 BP. Data recovery efforts defined FCR features 8 through 13. In addition, 24 arrow points, several dart points, a variety of unifacial and bifacial tools, a small number of cores, roughly 6,000 pieces of debitage, and a variety of burned sandstone, were recovered. We also collected small quantities of bone and mussel shell along with about 14,350 gastropod shells, and a variety of soil samples. Finally, all calcium carbonate nodules were retained from the screens. Following the completion of data recovery efforts, the CAR was directed by TxDOT to develop a research design for the analysis of the material from 41ZV202. TxDOT and THC accepted that research design in November of 2004, at which time the CAR began analysis and report production. Unfortunately, by 2005 project archeologist Russell Greaves had left the CAR. At that point, CAR assistant director Dr. Raymond Mauldin took over the project. The analysis of the 41ZV202 Late Prehistoric data outlined in this report is conducted in the context of a large-scale, theoretically driven model of adaptation for hunters and gatherers loosely based on aspects of Optimal Foraging Theory. In addition to 41ZV202, the approach relies on comparative data sets from Late Archaic and other Late Prehistoric sites from South and South-Central Texas to investigate shifts in subsistence, technology, and mobility across this broad region. At this time, discard decisions have not been made. However, all artifacts and associated samples collected and retained during this project, along with all project-associated documentation, are to be permanently curated at the CAR according to Texas Historical Commission guidelines

    Upper limb prostheses: bridging the sensory gap

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    Replacing human hand function with prostheses goes far beyond only recreating muscle movement with feedforward motor control. Natural sensory feedback is pivotal for fine dexterous control and finding both engineering and surgical solutions to replace this complex biological function is imperative to achieve prosthetic hand function that matches the human hand. This review outlines the nature of the problems underlying sensory restitution, the engineering methods that attempt to address this deficit and the surgical techniques that have been developed to integrate advanced neural interfaces with biological systems. Currently, there is no single solution to restore sensory feedback. Rather, encouraging animal models and early human studies have demonstrated that some elements of sensation can be restored to improve prosthetic control. However, these techniques are limited to highly specialized institutions and much further work is required to reproduce the results achieved, with the goal of increasing availability of advanced closed loop prostheses that allow sensory feedback to inform more precise feedforward control movements and increase functionality

    A systematic analysis of the human immune response to Plasmodium vivax

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    Background. The biology of Plasmodium vivax is markedly different from that of P. falciparum; how this shapes the immune response to infection remains unclear. To address this shortfall, we inoculated human volunteers with a clonal field isolate of P. vivax and tracked their response through infection and convalescence. Methods. Participants were injected intravenously with blood-stage parasites and infection dynamics were tracked in real time by quantitative PCR. Whole blood samples were used for high dimensional protein analysis, RNA sequencing, and cytometry by time of flight, and temporal changes in the host response to P. vivax were quantified by linear regression. Comparative analyses with P. falciparum were then undertaken using analogous data sets derived from prior controlled human malaria infection studies. Results. P. vivax rapidly induced a type I inflammatory response that coincided with hallmark features of clinical malaria. This acute-phase response shared remarkable overlap with that induced by P. falciparum but was significantly elevated (at RNA and protein levels), leading to an increased incidence of pyrexia. In contrast, T cell activation and terminal differentiation were significantly increased in volunteers infected with P. falciparum. Heterogeneous CD4+ T cells were found to dominate this adaptive response and phenotypic analysis revealed unexpected features normally associated with cytotoxicity and autoinflammatory disease. Conclusion. P. vivax triggers increased systemic interferon signaling (cf P. falciparum), which likely explains its reduced pyrogenic threshold. In contrast, P. falciparum drives T cell activation far in excess of P. vivax, which may partially explain why falciparum malaria more frequently causes severe disease. Trial registration. ClinicalTrials.gov NCT03797989. Funding. The European Union’s Horizon 2020 Research and Innovation programme, the Wellcome Trust, and the Royal Society
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