201 research outputs found

    Terahertz rectifyier for integrated image detector

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    We present a new CMOS compatible direct conversion terahertz detector operating at room temperature. The rectenna consists in a truncated conical helix extruded from a planar spiral and connected to a nanometric metallic whisker at one of its edges. The whisker reaches the semiconductor substrate that constitutes the antenna ground plane. The rectifying device can be obtained introducing some simple modifications of the charge storage well in conventional CMOS APS devices, making the proposed solution easy to integrate with existing imaging systems. No need of scaling toward very scaled and costly technological node is required, since the CMOS only provides the necessary integrated readout electronics. On-wafer measurements of RF characteristics of the designed rectifying junction are reported and discussed

    A colloidal viewpoint on the finite sphere packing problem: the sausage catastrophe

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    It is commonly believed that the most efficient way to pack a finite number of equal-sized spheres is by arranging them tightly in a cluster. However, mathematicians have conjectured that a linear arrangement may actually result in the densest packing. Here, our combined experimental and simulation study provides a realization of the finite sphere packing problem by studying non-close-packed arrangements of colloids in a flaccid lipid vesicle. We map out a state diagram displaying linear, planar and cluster conformations of spheres, as well as bistable states which alternate between cluster-plate and plate-linear conformations due to membrane fluctuations. Finally, by systematically analyzing truncated polyhedral packings, we identify clusters of 56N7056\leq N \leq 70 spheres, excluding N=57N=57 and 63, that pack more efficiently than linear arrangements

    Particle Content of the Nonlinear Sigma Model with Theta-Term: a Lattice Model Investigation

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    Using new as well as known results on dimerized quantum spin chains with frustration, we are able to infer some properties on the low-energy spectrum of the O(3) Nonlinear Sigma Model with a topological theta-term. In particular, for sufficiently strong coupling, we find a range of values of theta where a singlet bound state is stable under the triplet continuum. On the basis of these results, we propose a new renormalization group flow diagram for the Nonlinear Sigma Model with theta-term.Comment: 10 pages, 5 figures .eps, iopart format, submitted to JSTA

    Overexpression of microRNA-206 in the skeletal muscle from myotonic dystrophy type 1 patients

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    <p>Abstract</p> <p>Background</p> <p>MicroRNAs are highly conserved, noncoding RNAs involved in post-transcriptional gene silencing. They have been shown to participate in a wide range of biological processes, including myogenesis and muscle regeneration. The goal of this study is to test the hypothesis that myo-miRs (myo = muscle + miR = miRNA) expression is altered in muscle from patients affected by myotonic dystrophy type 1 (DM1), the most frequently inherited neuromuscular disease in adults. In order to gain better insights about the role of miRNAs in the DM1 pathogenesis, we have also analyzed the muscular expression of miR-103 and miR-107, which have been identified <it>in silico </it>as attractive candidates for binding to the <it>DMPK </it>mRNA.</p> <p>Methods</p> <p>To this aim, we have profiled the expression of miR-133 (miR-133a, miR-133b), miR-1, miR-181 (miR-181a, miR-181b, miR-181c) and miR-206, that are specifically induced during myogenesis in cardiac and skeletal muscle tissues. miR-103 and miR-107, highly expressed in brain, heart and muscle have also been included in this study. QRT-PCR experiments have been performed on RNA from vastus lateralis biopsies of DM1 patients (n = 7) and control subjects (n = 4). Results of miRNAs expression have been confirmed by Northern blot, whereas <it>in situ </it>hybridization technique have been performed to localize misexpressed miRNAs on muscle sections from DM1 and control individuals.</p> <p>Results</p> <p>Only miR-206 showed an over-expression in 5 of 7 DM1 patients (threshold = 2, fold change between 1.20 and 13.22, average = 5.37) compared to the control group. This result has been further confirmed by Northern blot analysis (3.37-fold overexpression, <it>R</it><sup>2 </sup>= 0.89). <it>In situ </it>hybridization localized miR-206 to nuclear site both in normal and DM1 tissues. Cellular distribution in DM1 tissues includes also the nuclear regions of centralized nuclei, with a strong signal corresponding to nuclear clumps.</p> <p>Conclusions</p> <p>This work provides, for the first time, evidences about miRNAs misexpression in DM1 muscle tissues, adding a new element in the pathogenesis of this complex genetic disease.</p

    Management of oral anticoagulant therapy after intracranial hemorrhage in patients with atrial fibrillation

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    Intracranial hemorrhage (ICH) is considered a potentially severe complication of oral anticoagulants (OACs) and antiplatelet therapy (APT). Patients with atrial fibrillation (AF) who survived ICH present both an increased ischemic and bleeding risk. Due to its lethality, initiating or reinitiating OACs in ICH survivors with AF is challenging. Since ICH recurrence may be life-threatening, patients who experience an ICH are often not treated with OACs, and thus remain at a higher risk of thromboembolic events. It is worthy of mention that subjects with a recent ICH and AF have been scarcely enrolled in randomized controlled trials (RCTs) on ischemic stroke risk management in AF. Nevertheless, in observational studies, stroke incidence and mortality of patients with AF who survived ICH had been shown to be significantly reduced among those treated with OACs. However, the risk of hemorrhagic events, including recurrent ICH, was not necessarily increased, especially in patients with post-traumatic ICH. The optimal timing of anticoagulation initiation or restarting after an ICH in AF patients is also largely debated. Finally, the left atrial appendage occlusion option should be evaluated in AF patients with a very high risk of recurrent ICH. Overall, an interdisciplinary unit consisting of cardiologists, neurologists, neuroradiologists, neurosurgeons, patients, and their families should be involved in management decisions. According to available evidence, this review outlines the most appropriate anticoagulation strategies after an ICH that should be adopted to treat this neglected subset of patients
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