225 research outputs found

    Inhibitors in Patients with Congenital Bleeding Disorders Other Than Hemophilia

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    The most worrying complication of replacement therapy for severe hemophilia A and B is currently the occurrence of inhibitory alloantibodies against infused factor VIII and factor IX, respectively. Inhibitors compromise the management of hemorrhage in affected patients, with a considerable increase in complications, disability, and costs. While these alloantibodies have been extensively studied in the past years in hemophilia A and B, those occurring in patients with other inherited bleeding disorders are less well characterized and still poorly understood, mostly due to the rarity of these hemorrhagic conditions. This narrative review will deal with inhibitors arising in patients with inherited bleeding disorders other than "classical" hemophilia, focusing in particular on those developing in patients with congenital deficiency of coagulation factor V, factor VII, factor XI, and factor XIII

    Result-Biased Distributed-Arithmetic-Based Filter Architectures for Approximately Computing the DWT

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    The discrete wavelet transform is a fundamental block in several schemes for image compression. Its implementation relies on filters that usually require multiplications leading to a relevant hardware complexity. Distributed arithmetic is a general and effective technique to implement multiplierless filters and has been exploited in the past to implement the discrete wavelet transform as well. This work proposes a general method to implement a discrete wavelet transform architecture based on distributed arithmetic to produce approximate results. The novelty of the proposed method relies on the use of result-biasing techniques (inspired by the ones used in fixed-width multiplier architectures), which cause a very small loss of quality of the compressed image (average loss of 0.11 dB and 0.20 dB in terms of PSNR for the 9/7 and 10/18 wavelet filters, respectively). Compared with previously proposed distributed-arithmetic-based architectures for the computation of the discrete wavelet transform, this technique saves from about 20% to 25% of hardware complexity

    Intrinsic Electric Oscillations of Ovonic Devices towards the TeraHerz limit

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    The time-dependent response of Ovonic devices to an electric potential ramp signal is analysed by means of an enhanced version of a previously published time-dependent charge- transport model proposed by the authors. Depending on the inevitable parasitics of the system, either stable or oscillating solutions are found according to the position of the load line. The model also allows for speculations on the potential of Ovonic materials in the design of high- frequency oscillating circuits close to the terahertz range

    Investigation of Amperometric Sensing Mechanism in Gold-C60-Gold Molecular Dot

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    We investigate through simulations the gold–C60–gold molecular junction as a novel single-molecule amperometric gas sensor. We find it promising for NO and NO2 detection in air and at room temperature, with current variations of the order of the microampere, and presenting the potential capability of achieving the single-molecule sensitivity along with selectivity in the presence of common atmospheric gases. Furthermore, and for the first time, we investigate the current modulation mechanism due to target–sensor intermolecular interactions, providing theoretical insights into the functioning and exclusive properties of this novel device. In particular, we show and motivate the peculiar voltage-dependent response of the sensor that we relate to the distinctive mechanism of transport modulation occurring in the presence of a specific target. Finally, we discuss sensing reliability in air and the effects of probable fabrication process variability on sensing performance. Our results motivate future works on molecular dot-based chemical sensors in terms of the sensor–target exclusive interactions and detection principles, oriented to device-level engineering to find optimal operating conditions

    Process Variability and Electrostatic Analysis of Molecular QCA

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    Molecular quantum-dot cellular automata (mQCA) is an emerging paradigm for nanoscale computation. Its revolutionary features are the expected operating frequencies (THz), the high device densities, the noncryogenic working temperature, and, above all, the limited power densities. The main drawback of this technology is a consequence of one of its very main advantages, that is, the extremely small size of a single molecule. Device prototyping and the fabrication of a simple circuit are limited by lack of control in the technological process [Pulimeno et al. 2013a]. Moreover, high defectivity might strongly impact the correct behavior of mQCA devices. Another challenging point is the lack of a solid method for analyzing and simulating mQCA behavior and performance, either in ideal or defective conditions. Our contribution in this article is threefold: (i) We identify a methodology based on both ab-initio simulations and post-processing of data for analyzing an mQCA system adopting an electronic point of view (we baptized this method as "MoSQuiTo"); (ii) we assess the performance of an mQCA device (in this case, a bis- ferrocene molecule) working in nonideal conditions, using as a reference the information on fabrication-critical issues and on the possible defects that we are obtaining while conducting our own ongoing experiments on mQCA: (iii) we determine and assess the electrostatic energy stored in a bis-ferrocene molecule both in an oxidized and reduced form. Results presented here consist of quantitative information for an mQCA device working in manifold driving conditions and subjected to defects. This information is given in terms of: (a) output voltage; (b) safe operating area (SOA); (c) electrostatic energy; and (d) relation between SOA and energy, that is, possible energy reduction subject to reliability and functionality constraints. The whole analysis is a first fundamental step toward the study of a complex mQCA circuit. It gives important suggestions on possible improvements of the technological processes. Moreover, it starts an interesting assessment on the energy of an mQCA, one of the most promising features of this technolog

    Electronic, optical and thermal properties of the hexagonal and fcc Ge2Sb2Te5 chalcogenide from first-principle calculations

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    We present a comprehensive computational study on the properties of face-centered cubic and hexagonal chalcogenide Ge2Sb2Te5. We calculate the electronic structure using density functional theory (DFT); the obtained density of states (DOS) compares favorably with experiments, also looking suitable for transport analysis. Optical constants including refraction index and absorption coefficient capture major experimental features, aside from an energy shift owed to an underestimate of the band gap that is typical of DFT calculations. We also compute the phonon DOS for the hexagonal phase, obtaining a speed of sound and thermal conductivity in good agreement with the experimental lattice contribution. The calculated heat capacity reaches ~ 1.4 x 106 J/(m3 K) at high temperature, in agreement with experimental data, and provides insight into the low-temperature range (< 150 K), where data are unavailable.Comment: 19 pages, 8 figure

    Surface study of selected biomaterials using vibrational spectroscopy

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    Vibrational spectroscopy has been extensively used for in vitro and in vivo investigations of degradation mechanism and kinetics of different biomedical materials as well as it has been used to characterize the crystalline and amorphous domains in bio-mineralization process. Infrared and Raman spectroscopy methods are valuable tools in the biomaterials engineering allowing to study processes occurring during their preparation. In vitro tests, where the materials are immersed in simulated body fluids and/or artificial saliva, were used to evaluate the biocompatibility of biomaterials. This kind of tests are a wide range of repeatable and reproducible methods, which are regulated by international standards for commercial use and scientific development of new materials and products. The aim of this work was to examine phase composition of materials applied in dentistry. The bioactivity of such biomaterials was studied by immersing the samples in synthetic body fluid and artificial saliva. The changes were determined by the Fourier transform infrared and Raman microspectroscopy as well as scanning electron microscopy. It was found that results obtained by vibrational spectroscopy show the differences between the studied samples. Chemical reactions occurring during incubation of cements in artificial saliva as well as in synthetic body fluid result in formation of phosphates which deposit on the cement surface

    Muon-electron scattering at NLO

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    We consider the process of muon-electron elastic scattering, which has been proposed as an ideal framework to measure the running of the electromagnetic coupling constant at space-like momenta and determine the leading-order hadronic contribution to the muon g−2g-2 (MUonE experiment). We compute the next-to-leading (NLO) contributions due to QED and purely weak corrections and implement them into a fully differential Monte Carlo event generator, which is available for first experimental studies. We show representative phenomenological results of interest for the MUonE experiment and examine in detail the impact of the various sources of radiative corrections under different selection criteria, in order to study the dependence of the NLO contributions on the applied cuts. The study represents the first step towards the realisation of a high-precision Monte Carlo code necessary for data analysis.Comment: 25 pages, 2 tables, 14 figures. Minor typos corrected, reference 31 updated. Version matching publication on JHE

    Electronic Transport Study of Bistable Cr@C28 Single-Molecule Device for High-Density Data Storage Applications

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    We investigate through ab initio calculation the endohedral monometallofullerene Cr@C28 as a candidate for data storage applications. First, we study the encapsulation energy and the electronic properties of two stable states of the Cr@C28 - namely I-Cr@C28 and II-Cr@C28. Then, we address the adsorption of C28, I-Cr@C28, and II-Cr@C28 onto a gold substrate. Finally, by emulating a Scanning Tunneling Microscope (STM) break-junction experimental setup, we analyze the STM-mediated transport characteristics for the most probable adsorption configurations. We find and discuss a significant and measurable current difference between the two stable states. This outcome enables the binary encoding of the information, making the proposed device promising as a single-molecule data storage element for future high-density integrated circuits
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