1,805 research outputs found

    Trunk Control And Standing Tolerance Of A Patient With Paraparesis As A Result Of Transverse Myelitis And Mycotic Aneurysm Rupture: A Case Report

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    Background and Purpose: Transverse myelitis (TM) is a rare condition in which the spinal cord becomes inflamed resulting in pain, paraparesis or paraplegia, impaired sensation, and/or impaired autonomic function. Approximately two-thirds recover with mild to moderate symptoms, but one-third are left with severe and disabling symptoms. Cerebral mycotic aneurysm (CMA) rupture is a brain injury due to a burst artery resulting in diminished blood supply to the brain. There is literature on beneficial physical therapy (PT) intervention progressions following brain injury, such as bed mobility strategies and pre-gait activities, but there is little published on PT for impairments as a result of concurrent TM and CMA ruptures. The purpose of this case report was to describe the PT interventions provided to a patient with paraparesis as a result of TM and multiple CMA ruptures to progress toward achieving his goals of standing and ambulating with a standard walker and bilateral knee-ankle-foot-orthoses (KAFOs). Case Description: The 28-year-old male patient had been seen for two years at an outpatient clinic with an accredited brain injury program. The patient encountered several barriers throughout his rehabilitation, such as repairs to his KAFOs and low bone mineral density, which resulted in a decrease in standing tolerance over time. Outcomes: The Brain Injury Assessment Tool (BIAT) and manual muscle testing were used to document changes throughout the patient’s period of care. No significant changes were observed. Discussion: This patient, despite minimal improvements over a two-year period, may have the potential to increase his trunk control and standing tolerance if he has an extended period of time with no barriers to his rehabilitation

    Toda Fields on Riemann Surfaces: remarks on the Miura transformation

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    We point out that the Miura transformation is related to a holomorphic foliation in a relative flag manifold over a Riemann Surface. Certain differential operators corresponding to a free field description of WW--algebras are thus interpreted as partial connections associated to the foliation.Comment: AmsLatex 1.1, 10 page

    Entire curves avoiding given sets in C^n

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    Let FCnF\subset\Bbb C^n be a proper closed subset of Cn\Bbb C^n and ACnFA\subset\Bbb C^n\setminus F at most countable (n2n\geq 2). We give conditions of FF and AA, under which there exists a holomorphic immersion (or a proper holomorphic embedding) ϕ:CCn\phi:\Bbb C\to\Bbb C^n with Aϕ(C)CnFA\subset\phi(\Bbb C)\subset\Bbb C^n\setminus F.Comment: 10 page

    Laser beam steering device

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    Agile beam steering is a critical requirement for airborne and space based LIDAR and optical communication systems. Design and test results are presented for a compact beam steering device with low inertia which functions by dithering two complementary (positive and negative) binary optic microlens arrays relative to each other in directions orthogonal to the direction of light propagation. The miniaturized system has been demonstrated at scan frequencies as high as 300 Hz, generating a 13 x 13 spot array with a total field of view of 2.4 degrees. The design is readily extendable to a 9.5 degree field of view and a 52 x 52 scan pattern. The system is compact - less than 2 in. on a side. Further size reductions are anticipated

    Strong asymptotics for Cauchy biorthogonal polynomials with application to the Cauchy two--matrix model

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    We apply the nonlinear steepest descent method to a class of 3x3 Riemann-Hilbert problems introduced in connection with the Cauchy two-matrix random model. The general case of two equilibrium measures supported on an arbitrary number of intervals is considered. In this case, we solve the Riemann-Hilbert problem for the outer parametrix in terms of sections of a spinorial line bundle on a three-sheeted Riemann surface of arbitrary genus and establish strong asymptotic results for the Cauchy biorthogonal polynomials.Comment: 31 pages, 12 figures. V2; typos corrected, added reference

    Large-scale multielectrode recording and stimulation of neural activity

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    Large circuits of neurons are employed by the brain to encode and process information. How this encoding and processing is carried out is one of the central questions in neuroscience. Since individual neurons communicate with each other through electrical signals (action potentials), the recording of neural activity with arrays of extracellular electrodes is uniquely suited for the investigation of this question. Such recordings provide the combination of the best spatial (individual neurons) and temporal (individual action-potentials) resolutions compared to other large-scale imaging methods. Electrical stimulation of neural activity in turn has two very important applications: it enhances our understanding of neural circuits by allowing active interactions with them, and it is a basis for a large variety of neural prosthetic devices. Until recently, the state-of-the-art in neural activity recording systems consisted of several dozen electrodes with inter-electrode spacing ranging from tens to hundreds of microns. Using silicon microstrip detector expertise acquired in the field of high-energy physics, we created a unique neural activity readout and stimulation framework that consists of high-density electrode arrays, multi-channel custom-designed integrated circuits, a data acquisition system, and data-processing software. Using this framework we developed a number of neural readout and stimulation systems: (1) a 512-electrode system for recording the simultaneous activity of as many as hundreds of neurons, (2) a 61-electrode system for electrical stimulation and readout of neural activity in retinas and brain-tissue slices, and (3) a system with telemetry capabilities for recording neural activity in the intact brain of awake, naturally behaving animals. We will report on these systems, their various applications to the field of neurobiology, and novel scientific results obtained with some of them. We will also outline future directions

    Ferromagnetism in defect-ridden oxides and related materials

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    The existence of high-temperature ferromagnetism in thin films and nanoparticles of oxides containing small quantities of magnetic dopants remains controversial. Some regard these materials as dilute magnetic semiconductors, while others think they are ferromagnetic only because the magnetic dopants form secondary ferromagnetic impurity phases such as cobalt metal or magnetite. There are also reports in d0 systems and other defective oxides that contain no magnetic ions. Here, we investigate TiO2 (rutile) containing 1 - 5% of iron cations and find that the room-temperature ferromagnetism of films prepared by pulsed-laser deposition is not due to magnetic ordering of the iron. The films are neither dilute magnetic semiconductors nor hosts to an iron-based ferromagnetic impurity phase. A new model is developed for defect-related ferromagnetism which involves a spin-split defect band populated by charge transfer from a proximate charge reservoir in the present case a mixture Fe2+ and Fe3+ ions in the oxide lattice. The phase diagram for the model shows how inhomogeneous Stoner ferromagnetism depends on the total number of electrons Ntot, the Stoner exchange integral I and the defect bandwidth W; the band occupancy is governed by the d-d Coulomb interaction U. There are regions of ferromagnetic metal, half-metal and insulator as well as nonmagnetic metal and insulator. A characteristic feature of the high-temperature Stoner magnetism is an an anhysteretic magnetization curve which is practically temperature independent below room temperature. This is related to a wandering ferromagnetic axis which is determined by local dipole fields. The magnetization is limited by the defect concentration, not by the 3d doping. Only 1-2 % of the volume of the films is magnetically ordered.Comment: 22 pages, 6 figure

    Does consumer protection enhance disclosure credibility in reward crowdfunding?

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    We study how the interplay of disclosure and regulation shapes capital allocation in reward crowdfunding. Using data from Kickstarter, the largest online reward crowdfunding platform, we show that, even in the absence of clear regulation and enforcement mechanisms, disclosure helps entrepreneurs access capital for their projects and bolsters engagement with potential project backers, consistent with the notion that disclosure mitigates moral hazard. We further document that, subsequent to a change in Kickstarter’s terms of use that increases the threat of consumer litigation, the association between project funding and disclosure becomes stronger. This evidence suggests that consumer protection regulation enhances the perceived credibility of disclosure. We find the effect of the change in terms of use to be more pronounced in states with stricter consumer protection regulations. Taken together, our findings yield important insights on the role of disclosure, as well as on the potential effects of increased regulation on crowdfunding platforms
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