6,194 research outputs found

    Locality and Translations in Braided Ribbon Networks

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    An overview of microlocality in braided ribbon networks is presented. Following this, a series of definitions are presented to explore the concept of microlocality and the topology of ribbon networks. Isolated substructure of ribbon networks are introduced, and a theorem is proven that allows them to be relocated. This is followed by a demonstration of microlocal translations. Additionally, an investigation into macrolocality and the implications of invariants in braided ribbon networks are presented.Comment: 12 pages, 12 figure

    An optical fiber hydrogen sensor using a palladium-coated ball lens

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    A self-referenced optical fiber refractometer using a ball lens as a sensor head has been developed and characterized. A 350-μm ball lens created at the tip of a single mode fiber has been coated with a 40-nm optically thin layer of palladium that reacts with hydrogen to form a hydride, which has a lower reflectivity than pure palladium. Optical reflectance measurements from the tip of the ball lens were performed to determine the hydrogen response. The change in reflectivity is proportional to the hydrogen concentration in the range 0% to 1% hydrogen in air with a detection limit down to 10 ppm (1σ) in air. This technique offers a simple sensor head arrangement, with a larger sampling area (~40 times) than a typical single-mode fiber core. A statistical image analysis of a palladium film, with cracks created by accelerated failure, confirms that the anticipated sensor area for a ball lens sensor head has a more predictable reflectivity than that of a bare fiber core

    Differential Hox expression in murine embryonic stem cell models of normal and malignant hematopoiesis

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    The Hox family are master transcriptional regulators of developmental processes, including hematopoiesis. The Hox regulators, caudal homeobox factors (Cdx1-4), and Meis1, along with several individual Hox proteins, are implicated in stem cell expansion during embryonic development, with gene dosage playing a significant role in the overall function of the integrated Hox network. To investigate the role of this network in normal and aberrant, early hematopoiesis, we employed an in vitro embryonic stem cell differentiation system, which recapitulates mouse developmental hematopoiesis. Expression profiles of Hox, Pbx1, and Meis1 genes were quantified at distinct stages during the hematopoietic differentiation process and compared with the effects of expressing the leukemic oncogene Tel/PDGFR;2. During normal differentiation the Hoxa cluster, Pbx1 and Meis1 predominated, with a marked reduction in the majority of Hox genes (27/39) and Meis1 occurring during hematopoietic commitment. Only the posterior Hoxa cluster genes (a9, a10, a11, and a13) maintained or increased expression at the hematopoietic colony stage. Cdx4, Meis1, and a subset of Hox genes, including a7 and a9, were differentially expressed after short-term oncogenic (Tel/PDGFR;2) induction. Whereas Hoxa4-10, b1, b2, b4, and b9 were upregulated during oncogenic driven myelomonocytic differentiation. Heterodimers between Hoxa7/Hoxa9, Meis1, and Pbx have previously been implicated in regulating target genes involved in hematopoietic stem cell (HSC) expansion and leukemic progression. These results provide direct evidence that transcriptional flux through the Hox network occurs at very early stages during hematopoietic differentiation and validates embryonic stem cell models for gaining insights into the genetic regulation of normal and malignant hematopoiesis

    Reoperative brachial plexus neurolysis after previous anatomically complete supraclavicular decompression for neurogenic thoracic outlet syndrome: A 10-year single-center case series

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    BACKGROUND: Optimal management of recurrent neurogenic thoracic outlet syndrome (NTOS) remains a considerable challenge. OBJECTIVE: To assess the safety and effectiveness of reoperative brachial plexus neurolysis in patients with recurrent NTOS. METHODS: From 2009 to 2019, 85 patients underwent reoperative supraclavicular brachial plexus neurolysis for recurrent NTOS after a previous anatomically complete supraclavicular decompression. Data from a prospectively maintained database were analyzed retrospectively. RESULTS: The mean patient age at reoperation was 36.9 ± 1.3 (range 15-64) years, 75% were female, and the interval after previous primary operation was 2.5 ± 0.2 years. Intervening injury had precipitated recurrent NTOS in 14 patients (16%), and the mean Disability of the Arm, Shoulder, and Hand (QuickDASH) score before reoperation was 65.2 ± 2.6, reflecting substantial disability. Operative findings consisted of dense fibrous scar tissue surrounding/encasing the brachial plexus. Compared with the previous primary operations, reoperations had a shorter operative time (198 ± 4 vs 161 ± 5 minutes, P \u3c .01) and hospital stay (4.4 ± 0.2 vs 3.6 ± 0.1 days, P \u3c .01), but there were no significant differences in the frequency of prolonged hospitalization (7.1% vs 4.7%), early reoperation (3.5% vs 1.2%), or 30-day hospital readmission (8.2% vs 7.1%). During a median follow-up of 4.8 years, QuickDASH scores improved by 23.3 ± 2.6 (34.2% ± 3.6%; P \u3c .01) and patient-rated outcomes were excellent in 24%, good in 42%, fair in 26%, and poor in 8%. CONCLUSION: Reoperative supraclavicular brachial plexus neurolysis is technically challenging but safe and effective treatment for recurrent NTOS, with significant improvements in symptoms and function. Diminishing perineural scar tissue development and avoiding secondary injury would likely decrease the need for reoperations

    The Resolved Near-Infrared Extragalactic Background

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    We present a current best estimate of the integrated near-infrared (NIR) extragalactic background light (EBL) attributable to resolved galaxies in J, H, and Ks. Our results in units of nW m-2 sr-1 are 11.7+5.6 -2.6 in J, 11.5+4.5 -1.5 in H and 10.0+2.8 -0.8 in Ks. We derive these new limits by combining our deep wide-field NIR photometry from five widely separated fields with other studies from the literature to create a galaxy counts sample that is highly complete and has good counting statistics out to JHKs ~ 27-28. As part of this effort we present new ultradeep Ks-band galaxy counts from 22 hours of observations with the Multi Object Infrared Camera and Spectrograph (MOIRCS) instrument on the Subaru Telescope. We use this MOIRCS Ks-band mosaic to estimate the total missing flux from sources beyond our detection limits. Our new limits to the NIR EBL are in basic agreement with, but 10 - 20% higher than previous estimates, bringing them into better agreement with estimates of the total NIR EBL (resolved + unresolved sources) obtained from TeV gamma-ray opacity measurements and recent direct measurements of the total NIR EBL. We examine field to field variations in our photometry to show that the integrated light from galaxies is isotropic to within uncertainties, consistent with the expected large-scale isotropy of the EBL. Our data also allow for a robust estimate of the NIR light from Galactic stars, which we find to be 14.7 +/- 2.4 in J, 10.1 +/- 1.9 in H and 7.6 +/- 1.8 in Ks in units of nW m-2 sr-1.Comment: Accepted to Ap

    6-De­oxy-6-fluoro-d-galactose

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    The crystal structure unequivocally confirms the relative stereochemistry of the title compound, C6H11FO5. The absolute stereochemistry was determined by the use of d-galactose as the starting material. The compound exists as a three-dimensional O—H⋯O hydrogen-bonded network with each mol­ecule acting as a donor and acceptor for four hydrogen bonds

    Imaging language pathways predicts postoperative naming deficits

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    Naming difficulties are a well recognised, but difficult to predict, complication of anterior temporal lobe resection (ATLR) for refractory epilepsy. We used MR tractography preoperatively to demonstrate the structural connectivity of language areas in patients undergoing dominant hemisphere ATLR. Greater lateralisation of tracts to the dominant hemisphere was associated with greater decline in naming function. We suggest that this method has the potential to predict language deficits in patients undergoing ATLR

    Motion of a driven tracer particle in a one-dimensional symmetric lattice gas

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    We study the dynamics of a tracer particle subject to a constant driving force EE in a one-dimensional lattice gas of hard-core particles whose transition rates are symmetric. We show that the mean displacement of the driven tracer grows in time, tt, as αt \sqrt{\alpha t}, rather than the linear time dependence found for driven diffusion in the bath of non-interacting (ghost) particles. The prefactor α\alpha is determined implicitly, as the solution of a transcendental equation, for an arbitrary magnitude of the driving force and an arbitrary concentration of the lattice gas particles. In limiting cases the prefactor is obtained explicitly. Analytical predictions are seen to be in a good agreement with the results of numerical simulations.Comment: 21 pages, LaTeX, 4 Postscript fugures, to be published in Phys. Rev. E, (01Sep, 1996
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