741 research outputs found

    Directional TGV-based image restoration under Poisson noise

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    We are interested in the restoration of noisy and blurry images where the texture mainly follows a single direction (i.e., directional images). Problems of this type arise, for example, in microscopy or computed tomography for carbon or glass fibres. In order to deal with these problems, the Directional Total Generalized Variation (DTGV) was developed by Kongskov et al. in 2017 and 2019, in the case of impulse and Gaussian noise. In this article we focus on images corrupted by Poisson noise, extending the DTGV regularization to image restoration models where the data fitting term is the generalized Kullback–Leibler divergence. We also propose a technique for the identifica-tion of the main texture direction, which improves upon the techniques used in the aforementioned work about DTGV. We solve the problem by an ADMM algorithm with proven convergence and subproblems that can be solved exactly at a low computational cost. Numerical results on both phantom and real images demonstrate the effectiveness of our approach

    Primary gas thermometry by means of laser-absorption spectroscopy: Determination of the Boltzmann constant

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    We report on a new optical implementation of primary gas thermometry based on laser absorption spectrometry in the near infrared. The method consists in retrieving the Doppler broadening from highly accurate observations of the line shape of the R(12) ν1+2ν210+ν3\nu_{1} + 2 \nu_{2}^{\phantom{1}0} + \nu_{3} transition in CO2_{2} gas at thermodynamic equilibrium. Doppler width measurements as a function of gas temperature, ranging between the triple point of water and the gallium melting point, allowed for a spectroscopic determination of the Boltzmann constant with a relative accuracy of 1.6×104\sim1.6\times10^{-4}.Comment: Submitted to Physical Review Letter

    Effects of thyroid hormone on the cardiovascular system

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    Increased or reduced action of thyroid hormone on certain molecular pathways in the heart and vasculature causes relevant cardiovascular derangements. It is well established that overt hyperthyroidism induces a hyperdynamic cardiovascular state (high cardiac output with low systemic vascular resistance), which is associated with a faster heart rate, enhanced left ventricular (LV) systolic and diastolic function, and increased prevalence of supraventricular tachyarrhythmias - namely, atrial fibrillation - whereas overt hypothyroidism is characterized by the opposite changes. However, whether changes in cardiac performance associated with overt thyroid dysfunction are due mainly to alterations of myocardial contractility or to loading conditions remains unclear. Extensive evidence indicates that the cardiovascular system responds to the minimal but persistent changes in circulating thyroid hormone levels, which are typical of individuals with subclinical thyroid dysfunction. Subclinical hyperthyroidism is associated with increased heart rate, atrial arrhythmias, increased LV mass, impaired ventricular relaxation, reduced exercise performance, and increased risk of cardiovascular mortality. Subclinical hypothyroidism is associated with impaired LV diastolic function and subtle systolic dysfunction and an enhanced risk for atherosclerosis and myocardial infarction. Because all cardiovascular abnormalities are reversed by restoration of euthyroidism ("subclinical hypothyroidism") or blunted by beta-blockade and L-thyroxine (L-T4) dose tailoring ("subclinical hyperthyroidism"), timely treatment is advisable in an attempt to avoid adverse cardiovascular effects. Interestingly, some data indicate that patients with acute and chronic cardiovascular disorders and those undergoing cardiac surgery may have altered peripheral thyroid hormone metabolism that, in turn, may contribute to altered cardiac function. Preliminary clinical investigations suggest that administration of thyroid hormone or its analogue 3,5-diiodothyropropionic acid greatly benefits these patients, highlighting the potential role of thyroid hormone treatment in patients with acute and chronic cardiovascular disease

    New Perspective in HCV Clinical and Economical Management of the Current and Future Therapies

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    Hepatitis C virus (HCV) is a progressive disease that infects more than 185 million individuals worldwide and is associated with persistence of viral replication and ongoing necroinflammation and fibrosis. To date 20% of patients chronically infected with HCV progress to cirrhosis. Epidemiological studies demonstrate that the incidence of HCV is not well known, because acute infection is generally asymptomatic. The global prevalence is about 2.2% and there is a large degree of geographic variability. Before the 2011, the gold standard of therapy for the treatment of chronic hepatitis C (CHC) was based on the combination of pegylated Interferon (peg-IFN) and Ribavirin (RBV). However, several aspects related to safety profile limited their use in clinical practice. In the recent years, thanks to basic research on HCV structure and replicative cycle, it has been possible to develop direct acting antiviral drugs that have dramatically increased the viral clearance rate. Specifically, the advent of the triple therapy employing direct acting antivirals has dramatically increased the viral clearance rate, from less than 10%, with the initial regimen of IFN monotherapy, to more than 95% with the current therapy. Even though new medications for hepatitis C are effective disease modifiers and have the potential, in a long term perspective, to eradicate the pathology, the cost of new treatments are unlikely to be sustainable for the NHSs. The evidence documenting the effectiveness and tolerability of the new therapies for HCV and several pharmacoeconomic analysis, shows that despite the cost, the new treatments can be considered cost-effective in the long period. However, the health care systems are unable to compensate the height financial resources immediately needed for treating patients with the long terms savings that will be obtained from the eradication of HCV. Indeed, new pharmaceutical policy and a global commitment is required to improve strategies of treatment and price negotiation with pharmaceutical companies to move from a theoretical cost-effectiveness approach to a practical cost-sustainable reality

    Via-Less Microstrip to Rectangular Waveguide Transition on InP

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    Indium-Phosphide (InP) is one of the most common materials used for realizing active devices working in the millimeter frequency range. The isotropic etching profile of InP substrates limits the realization of passive devices, thus requiring an expensive and lossy hybrid platform. This paper presents a via-less, cost-effective and efficient solution for InP substrate. By using the proposed planar solution, it is demonstrated that rectangular waveguides can be realized on InP by fabricating a bed of nails structure which acts as a reflecting boundary for an impinging millimeter wave. As a proof of concept, a transition from microstrip to rectangular waveguide structure is realized within H-band (220-320 GHz) with a return loss of -18dB over a bandwidth of 30 GHz

    Differential Control of Notch1 Gene Transcription by Klf4 and Sp3 Transcription Factors in Normal versus Cancer-Derived Keratinocytes

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    In specific cell types like keratinocytes, Notch signaling plays an important pro-differentiation and tumor suppressing function, with down-modulation of the Notch1 gene being associated with cancer development. Besides being controlled by p53, little else is known on regulation of Notch1 gene expression in this context. We report here that transcription of this gene is driven by a TATA-less “sharp peak” promoter and that the minimal functional region of this promoter, which extends from the −342 bp position to the initiation codon, is differentially active in normal versus cancer cells. This GC rich region lacks p53 binding sites, but binds Klf4 and Sp3. This finding is likely to be of biological significance, as Klf4 and, to a lesser extent, Sp3 are up-regulated in a number of cancer cells where Notch1 expression is down-modulated, and Klf4 over-expression in normal cells is sufficient to down-modulate Notch1 gene transcription. The combined knock-down of Klf4 and Sp3 was necessary for the reverse effect of increasing Notch1 transcription, consistent with the two factors exerting an overlapping repressor function through their binding to the Notch1 promoter

    Flexible multi-band OFDM receiver based on optical down-conversion for millimeter waveband wireless base stations

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    A novel and flexible photonics-based down-conversion scheme is proposed for wireless receivers in base stations. It allows simultaneous detection of multiple signals at carriers up to tens of GHz, enabling communications at millimeter waves. Experiments demonstrate the effective down-conversion of Wi-Fi signals at 2.4 and 39.8GHz with EVM<;-43dB

    Quantum Radar: State of the Art and Potential of a Newly-Born Remote Sensing Technology

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    Quantum technology has already been introduced in many fields, like information processing and communications, and it can potentially change our approach to remote sensing in the microwave and millimeter-wave domain, leading to systems known as Quantum Radars. This new generation of systems does not leverage directly on quantum entanglement, since the latter is too “fragile” to preserve in a noisy and lossy environment,as a radar scenario,but rather on thehigh level of coherence derived from quantum entanglement. Quantum Illuminationisaprocess that exploitsquantum coherence of non-classical states of lightfor remote sensing. It allows for the generation and reception of highly correlatedsignals in the form of optical ormicrowave photons. By correlating the received signal photons with photons entangled with the transmitted ones,it is possible toclearly distinguish, among all the received photons, the echoes from background noise and interferences, boosting to an unprecedented level the sensitivity of remote sensing. Therefore, in principle,it is possible to detect very lowcross-radar section objets, such as stealth targets. Nowadays, very few experiments on Quantum Radar transceivers have been reported. This work aims at summarizing the state of the art of Quantum Radar, introducing its basic working principles, though raising the possible issues of such a technology; secondly, it will point out the possibilitiesof photonics-assisted Quantum Radars, proposing photonics as the ideal field where quantum science and remote sensing can meet for an effective cross-fertilizatio

    Compositional inhomogeneity of an unusual Selinunte coin

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    EDXRF and XPS characterizations of a recently found Selinunte ancient coin are presented. Such a coin was found as essentially made up by a Sn-Pb alloy and its types have a very strong similarity with those shown by a silver set issued in the same historical period. It has been also studied by means of a SEMEDXRF coupled apparatus in order to have information about the compositional inhomogeneity of the alloy. XPS measurements have been used to provide a more surface sensitive analysis. The different probing depths of the adopted techniques have been found useful in evidencing volume inhomogeneities of the sample, at least in the first few microns above its surface. From an archaeological point of view, the coin may be ascribed to a coinage for funerary use or, more probably, to a coin production carried out during the difficult economic period of the history of Selinunte, immediately preceding the year 409 b.C., when the city was destroyed by Carthaginian armies

    Nature-derived compounds modulating Wnt/β-catenin pathway: a preventive and therapeutic opportunity in neoplastic diseases

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    Abstract The Wnt/β-catenin signaling is a conserved pathway that has a crucial role in embryonic and adult life. Dysregulation of the Wnt/β-catenin pathway has been associated with diseases including cancer, and components of the signaling have been proposed as innovative therapeutic targets, mainly for cancer therapy. The attention of the worldwide researchers paid to this issue is increasing, also in view of the therapeutic potential of these agents in diseases, such as Parkinson's disease (PD), for which no cure is existing today. Much evidence indicates that abnormal Wnt/β-catenin signaling is involved in tumor immunology and the targeting of Wnt/β-catenin pathway has been also proposed as an attractive strategy to potentiate cancer immunotherapy. During the last decade, several products, including naturally occurring dietary agents as well as a wide variety of products from plant sources, including curcunim, quercetin, berberin, and ginsenosides, have been identified as potent modulators of the Wnt/β-catenin signaling and have gained interest as promising candidates for the development of chemopreventive or therapeutic drugs for cancer. In this review we make an overview of the nature-derived compounds reported to have antitumor activity by modulating the Wnt/β-catenin signaling, also focusing on extraction methods, chemical features, and bio-activity assays used for the screening of these compounds
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