4,733 research outputs found

    SCHIP Children: How Long Do They Stay and Where Do They Go?

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    Presents findings on the length of children's enrollment in State Children's Health Insurance Programs and their coverage after they leave the program in seven states. Explores variations across states and how state policies may affect retention

    Early Surgery for Traumatic Spinal Cord Injury: Where Are We Now?

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    Study Design: Narrative review. Objective: There is a strong biological rationale to perform early decompression after traumatic spinal cord injury (SCI). With an enlarging clinical evidence base, most spine surgeons internationally now favor early decompression for the majority of SCI patients; however, a number of pertinent questions remain surrounding this therapy. Methods: A narrative review evaluating the status of early surgery for SCI. In particular, we addressed the following questions: (1) Which patients stand to benefit most from early surgery? 2) What is the most appropriate time threshold defining early surgery? Results: Although heterogeneity exists, the evidence generally seems to support early surgery. While the best evidence exists for cervical SCI, there is insufficient data to support a differential effect for early surgery depending on neurological level or injury severity. When comparing thresholds to define early versus late surgery-including a later threshold (48-72 hours), an earlier threshold (24 hours), and an ultra-early threshold (8-12 hours)-the 2 earlier time points seem to be associated with the greatest potential for improved outcomes. However, existing prehospital and hospital logistics pose barriers to early surgery in a significant proportion of patients. An overview of recommendations from the recent AOSpine guidelines is provided. Conclusion: In spite of increasing acceptance of early surgery post SCI, further research is needed to (1) identify subgroups of patients who stand to derive particular benefit-in particular to develop more evidence-based approaches for central cord syndrome and (2) investigate the efficacy and feasibility of ultra-early surgery targeting more aggressive timelines

    The modular synthesis of rare earth-transition metal heterobimetallic complexes utilizing a redox-active ligand

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    We report a robust and modular synthetic route to heterometallic rare earth-transition metal complexes. We have used the redox-active bridging ligand 1,10-phenathroline-5,6-dione (pd), which has selective N,Nā€² or O,Oā€² binding sites as the template for this synthetic route. The coordination complexes [Ln(hfac)3(N,Nā€™-pd)] (Ln = Y [1], Gd [2]; hfac = hexafluoroacetylacetonate) were synthesised in high yield. These complexes have been fully characterised using a range of spectroscopic techniques. Solid state molecular structures of 1 and 2 have been determined by X-ray crystallography and display different pd binding modes in coordinating and non-coordinating solvents. Complexes 1 and 2 are unusually highly coloured in coordinating solvents, for example the vis-NIR spectrum of 1 in acetonitrile displays an electronic transition centred at 587 nm with an extinction coefficient consistent with significant charge transfer. The reaction between 1 and 2 and VCp2 or VCpt2 (Cpt = tetramethylcyclopentadienyl) resulted in the isolation of the heterobimetallic complexes, [Ln(hfac)3(N,Nā€²-O,Oā€²-pd)VCp2] (Ln = Y [3], Gd [4]) or [Ln(hfac)3(N,Nā€²-O,Oā€²-pd)VCpt2] (Ln = Y [5], Gd [6]). The solid state molecular structures of 3, 5 and 6 have been determined by X-ray crystallography. The spectroscopic data on 3ā€“6 are consistent with oxidation of V(II) to V(IV) and reduction of pd to pd2āˆ’ in the heterobimetallic complexes. The spin-Hamiltonian parameters from low temperature X-band EPR spectroscopy of 3 and 5 describe a 2A1 ground state, with a V(IV) centre. DFT calculations on 3 are in good agreement with experimental data and confirm the SOMO as the dx2āˆ’y2 orbital localised on vanadium

    Development of ClpXP as a tool for investigating the mechanical properties of biomolecules applied to polyglutamine repeat proteins

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    It has become increasingly apparent that mechanical force plays an important role in biology. Biophysical techniques such as optical tweezers and atomic force microscopy (AFM) have allowed the investigation of mechanical stability at the level of a single protein molecule. However, despite the increasing sensitivity of these techniques, it is still difficult to mimic precisely the geometry of extension, forces and loading rates applied in vivo. Here we have developed a technique using a bacterial proteasome, ClpXP, which allowed the investigation of the mechanical stability of proteins at more biologically relevant forces and loading rates. It was demonstrated that various degradation signals can be used to target the proteins under investigation to ClpXP where they were unfolded, translocated and degraded. Several ClpX variants were investigated and an assay developed using a pseudohexameric ClpX variant that allowed robust degradation of several proteins. This assay was used to investigate the properties of a protein containing a 30 polyglutamine repeat sequence. Previous studies of polyglutamine repeats, using AFM, have shown that it may have interesting mechanical properties: it has either extreme mechanical strength, or access to a conformation which has a high mechanical strength. It was shown that this protein can be completely degraded using ClpXP without any intermediate product, and without reducing the degradation rate compared to a control protein without a polyglutamine repeat. This demonstrates that this assay can be used to investigate proteins whose mechanical properties are of interest and that the loading rates and application of force applied by this assay differ enough from those of AFM that different and more biologically relevant results can be obtained

    Additively manufactured bio-based composites

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    The development of new materials solutions for advanced manufacturing and fabrication technologies is an increasing focus of many research and development efforts in applied materials science today. Advances in these areas are resulting in the development of novel, geometrically complex parts and functional devices in a multitude of arenas, such as the biomedical and aerospace industries. Recent progress in materials research includes; the development of polymer systems that are less reliant on petroleum-based products, and are instead based on renewable, bio-derived sources. Concurrently, new additive manufacturing (AM) technologies are allowing the production of complex parts with structures and physical response not typically achievable through conventional manufacturing means. AM has become a leader in manufacturing complex and previously difficult to fabricate structures with fine features, by employing three-dimensional printing methods such as direct ink write (DIW) and stereolithography (SL). Our materials based approach has been to develop tailored and functional polymer based feedstocks for such AM processes to expand the range of these versatile fabrication technologies and explore new design space for AM. Here we present stimuli responsive, tailorable and robust class of, printable bio-based polymer composite that has been three dimensionally printed via additive manufacturing methods to have micro and macro scale complexity in features and exhibit a strong, tunable shape memory response. The development, characterization and potential applications of these novel shape memory polymer composite AM structures will be discussed

    Evidence for a supermassive object in the nucleus of the galaxy M87 from SIT and CCD area photometry

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    Two-dimensional SIT and CCD detectors have been used to measure the surface brightness of the peculiar elliptical radio galaxy M87. Measurements were made in three broad-band colors (B, V, and R) to a distance of 80" from the nucleus, with 1" spatial resolution and photometric accuracy of the order of 1%. The data are given in some detail and are compared with earlier photographic results. The most obvious feature of the data is a bright, barely resolved central luminosity spike, which is not seen in similar data on other nearby normal ellipticals. Also, attempts to fit isothermal or King models away from the nuclear spike show additional excess luminosity in the central regions of the galaxy (r 60. All of the existing data is well fitted by a King model containing a central black hole of mass M = 3 x 10^9 M_āŠ™ and a point luminosity source. While such a model is not uniquely required by the data, it is perhaps the most plausible of several possible models considered. At present, M87 is probably the best case for a hypothetical massive black hole in a galaxy nucleus
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