6,673 research outputs found

    Neuromodulation: present and emerging methods.

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    Neuromodulation has wide ranging potential applications in replacing impaired neural function (prosthetics), as a novel form of medical treatment (therapy), and as a tool for investigating neurons and neural function (research). Voltage and current controlled electrical neural stimulation (ENS) are methods that have already been widely applied in both neuroscience and clinical practice for neuroprosthetics. However, there are numerous alternative methods of stimulating or inhibiting neurons. This paper reviews the state-of-the-art in ENS as well as alternative neuromodulation techniques-presenting the operational concepts, technical implementation and limitations-in order to inform system design choices

    Contact of Single Asperities with Varying Adhesion: Comparing Continuum Mechanics to Atomistic Simulations

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    Atomistic simulations are used to test the equations of continuum contact mechanics in nanometer scale contacts. Nominally spherical tips, made by bending crystals or cutting crystalline or amorphous solids, are pressed into a flat, elastic substrate. The normal displacement, contact radius, stress distribution, friction and lateral stiffness are examined as a function of load and adhesion. The atomic scale roughness present on any tip made of discrete atoms is shown to have profound effects on the results. Contact areas, local stresses, and the work of adhesion change by factors of two to four, and the friction and lateral stiffness vary by orders of magnitude. The microscopic factors responsible for these changes are discussed. The results are also used to test methods for analyzing experimental data with continuum theory to determine information, such as contact area, that can not be measured directly in nanometer scale contacts. Even when the data appear to be fit by continuum theory, extracted quantities can differ substantially from their true values

    Towards low-latency real-time detection of gravitational waves from compact binary coalescences in the era of advanced detectors

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    Electromagnetic (EM) follow-up observations of gravitational wave (GW) events will help shed light on the nature of the sources, and more can be learned if the EM follow-ups can start as soon as the GW event becomes observable. In this paper, we propose a computationally efficient time-domain algorithm capable of detecting gravitational waves (GWs) from coalescing binaries of compact objects with nearly zero time delay. In case when the signal is strong enough, our algorithm also has the flexibility to trigger EM observation before the merger. The key to the efficiency of our algorithm arises from the use of chains of so-called Infinite Impulse Response (IIR) filters, which filter time-series data recursively. Computational cost is further reduced by a template interpolation technique that requires filtering to be done only for a much coarser template bank than otherwise required to sufficiently recover optimal signal-to-noise ratio. Towards future detectors with sensitivity extending to lower frequencies, our algorithm's computational cost is shown to increase rather insignificantly compared to the conventional time-domain correlation method. Moreover, at latencies of less than hundreds to thousands of seconds, this method is expected to be computationally more efficient than the straightforward frequency-domain method.Comment: 19 pages, 6 figures, for PR

    A scalable 32 channel neural recording and real-time FPGA based spike sorting system

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    This demo presents a scalable a 32-channel neural recording platform with real-time, on-node spike sorting ca- pability. The hardware consists of: an Intan RHD2132 neural amplifier; a low power Igloo ® nano FPGA; and an FX3 USB 3.0 controller. Graphical User Interfaces for controlling the system, displaying real-time data, and template generation with a modified form of WaveClus are demonstrated

    312 MAX Phases: Elastic Properties and Lithiation

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    Interest in the Mn+1AXn phases (M = early transition metal; A = group 13–16 elements, and X = C or N) is driven by their ceramic and metallic properties, which make them attractive candidates for numerous applications. In the present study, we use the density functional theory to calculate the elastic properties and the incorporation of lithium atoms in the 312 MAX phases. It is shown that the energy to incorporate one Li atom in Mo3SiC2, Hf3AlC2, Zr3AlC2, and Zr3SiC2 is particularly low, and thus, theoretically, these materials should be considered for battery applications

    State-Relevant Maxwell's Equation from Kaluza-Klein Theory

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    We study a five-dimensional perfect fluid coupled with Kaluza-Klein (KK) gravity. By dimensional reduction, a modified form of Maxwell's equation is obtained, which is relevant to the equation of state of the source. Since the relativistic magnetohydrodynamics (MHD) and the 3-dimensional formulation are widely used to study space matter, we derive the modified Maxwell's equations and relativistic MHD in 3+1 form. We then take an ideal Fermi gas as an example to study the modified effect, which can be visible under high density or high energy condition, while the traditional Maxwell's equation can be regarded as a result in the low density and low temperature limit. We also indicate the possibility to test the state-relevant effect of KK theory in a telluric laboratory.Comment: 11 pages, 3 figures; version published in PR

    Early hospital readmissions post‐kidney transplantation are associated with inferior clinical outcomes

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    Unplanned hospital readmissions are common early post‐kidney transplantation. We investigated the relationship between early hospital readmissions and clinical outcomes in a single‐center retrospective study that included all adult kidney transplant patients between 2004 and 2008 with follow‐up to December 2012. The early hospital readmissions within the first 30 d were numbered and the diagnosis ascertained. Patients were grouped as none, once, and twice or more readmissions. Predictors of early readmissions were assessed, and clinical outcomes and patient and death‐censored kidney survival were compared. Among 1064 patients, 203 (19.1%) patients had once and 83 (7.8%) patients had twice or more readmissions within 30 d. Surgical complications, infections, and acute kidney injuries/acute rejection were three most common diagnoses. The length of initial hospital stay and African American race were among the variables associated significantly with readmissions. Patients with early readmissions had lower baseline renal function (p < 0.01) and more early acute rejection (p < 0.01). During follow‐up, only frequent readmissions, twice or more, within 30 d were associated with increased risk of death ( AHR 1.75, p   =   0.01) and death‐censored kidney failure ( AHR 2.20, p < 0.01). Frequent early hospital readmissions post‐transplantation identify patients at risk for poor long‐term outcomes, and more studies are needed to understand the mechanisms.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106830/1/ctr12347.pd
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