1,495 research outputs found

    Dissipation and quantization for composite systems

    Full text link
    In the framework of 't Hooft's quantization proposal, we show how to obtain from the composite system of two classical Bateman's oscillators a quantum isotonic oscillator. In a specific range of parameters, such a system can be interpreted as a particle in an effective magnetic field, interacting through a spin-orbit interaction term. In the limit of a large separation from the interaction region one can describe the system in terms of two irreducible elementary subsystems which correspond to two independent quantum harmonic oscillators.Comment: 9 page

    Diffusion Processes and Coherent States

    Full text link
    It is shown that stochastic processes of diffusion type possess, in all generality, a structure of uncertainty relations and of coherent and squeezed states. This fact is used to obtain, via Nelson stochastic formulation of quantum mechanics, the harmonic-oscillator coherent and squeezed states. The method allows to derive new minimum uncertainty states in time-dependent oscillator potentials and for the Caldirola-Kanai model of quantum damped oscillator.Comment: 11 pages, plain LaTe

    Procedura di confronto tra AEP, INRIM e PTB per la taratura della macchina di taratura di forza per confronto da 5 MN del Laboratorio AEP.

    Get PDF
    During the period from March to June 2015, a comparison between the primary force standard machine of the Istituto Nazionale di Ricerca Metrologica (INRiM) in Turin and Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig (Germy) and the 5 MN calibration force machine for comparison of the accredited calibration Laboratory of AEP Transducers di Cognento (MO), has been carried out. The comparison, carried out according the calibration guide EURAMET cg-4, Version 2.0, following the Traceability Path A, has been used to perform the calibration of the calibration force machines

    Giant g factor tuning of long-lived electron spins in Ge

    Get PDF
    Control of electron spin coherence via external fields is fundamental in spintronics. Its implementation demands a host material that accommodates the highly desirable but contrasting requirements of spin robustness to relaxation mechanisms and sizeable coupling between spin and orbital motion of charge carriers. Here we focus on Ge, which, by matching those criteria, is rapidly emerging as a prominent candidate for shuttling spin quantum bits in the mature framework of Si electronics. So far, however, the intrinsic spin-dependent phenomena of free electrons in conventional Ge/Si heterojunctions have proved to be elusive because of epitaxy constraints and an unfavourable band alignment. We overcome such fundamental limitations by investigating a two dimensional electron gas (2DEG) confined in quantum wells of pure Ge grown on SiGe-buffered Si substrates. These epitaxial systems demonstrate exceptionally long spin relaxation and coherence times, eventually unveiling the potential of Ge in bridging the gap between spintronic concepts and semiconductor device physics. In particular, by tuning spin-orbit interaction via quantum confinement we demonstrate that the electron Land\'e g factor and its anisotropy can be engineered in our scalable and CMOS-compatible architectures over a range previously inaccessible for Si spintronics

    Autonomic dysfunction in progressive supranuclear palsy

    Get PDF
    Background: The degree of involvement of the autonomic nervous system in progressive supranuclear palsy (PSP) has been investigated in several studies, often providing conflicting results. There is a need for a better characterization of autonomic dysfunction in PSP, to enhance our understanding of this highly disabling neurodegenerative disease including patients’ needs and possibly be of value for clinicians in the differential diagnosis among Parkinsonian syndromes. Methods: We applied a systematic methodology to review existing literature on Pubmed regarding autonomic nervous system involvement in PSP. Results: PSP reported quite frequently symptoms suggestive of autonomic dysfunction in all domains. Cardiovascular autonomic testing showed in some cases a certain degree of impairment (never severe). There was some evidence suggesting bladder dysfunction particularly in the storage phase. Dysphagia and constipation were the most common gastrointestinal symptoms. Instrumental tests seemed to confirm sudomotor and pupillomotor disturbances. Conclusions: PSP patients frequently reported visceral symptoms, however objective testing showed that not always these reflected actual autonomic impairment. Further studies are needed to better delineate autonomic profile and its prognostic role in PSP

    The increase in hydric volume is associated to contractile impairment in the calf after the world's most extreme mountain ultra-marathon.

    Get PDF
    BACKGROUND: Studies have recently focused on the effect of running a mountain ultra-marathon (MUM) and their results show muscular inflammation, damage and force loss. However, the link between peripheral oedema and muscle force loss is not really established. We tested the hypothesis that, after a MUM, lower leg muscles' swelling could be associated with muscle force loss. The knee extensor (KE) and the plantar flexor (PF) muscles' contractile function was measured by supramaximal electrical stimulations, potentiated low- and high-frequency doublets (PS10 and PS100) of the KE and the PF were measured by transcutaneous electrical nerve stimulation and bioimpedance was used to assess body composition in the runners (n = 11) before (Pre) and after (Post) the MUM and compared with the controls (n = 8). RESULTS: The maximal voluntary contraction of the KE and the PF significantly decreased by 20 % Post-MUM in the runners. Hydration of the non-fat mass (NF-Hyd) and extracellular water volume (Ve) were increased by 12 % Post-MUM (p < 0.001) in the runners. Calf circumference (+2 %, p < 0.05) was also increased. Significant relationships were found for percentage increases in Ve and NF-Hyd with percentage decrease in PS10 of the PF (r = -0.68 and r = -0.70, p < 0.05) and with percentage increase of calf circumference (r = 0.72 and r = 0.73, p < 0.05) in the runners. CONCLUSIONS: The present study suggests that increases in circumference and in hydric volume are associated to contractile impairment in the calf in ultra-marathon runners

    Spin-dependent direct gap emission in tensile-strained Ge films on Si substrates

    Full text link
    The circular polarization of direct gap emission of Ge is studied in optically-excited tensile-strained Ge-on-Si heterostructures as a function of doping and temperature. Owing to the spin-dependent optical selection rules, the radiative recombinations involving strain-split light (cG-LH) and heavy hole (cG-HH) bands are unambiguously resolved. The fundamental cG-LH transition is found to have a low temperature circular polarization degree of about 85% despite an off-resonance excitation of more than 300 meV. By photoluminescence (PL) measurements and tight binding calculations we show that this exceptionally high value is due to the peculiar energy dependence of the optically-induced electron spin population. Finally, our observation of the direct gap doublet clarifies that the light hole contribution, previously considered to be negligible, can dominate the room temperature PL even at low tensile strain values of about 0.2%

    THE RISKS AND ADVANTAGES OF ANTI-DIABETES THERAPY IN THE POSITIVE COVID-19 PATIENT

    Get PDF
    The new Sars-Cov-2 (COVID-19) is causing thousands of deaths worldwide and has caused a global pandemic, one of the biggest health challenges ever faced in history. in the most severe cases, Sars-Cov-2 infection can cause fatal lung injuries. In this context, it is essential to recognise effective therapeutic agents against the virus. There are currently no direct and effective vaccines and antivirals available. People with pre-existing conditions, such as diabetes, and with chronic drug therapies in place may represent complex patients difficult to manage clinically during COVID-19 infection and at high risk of major complications. The regulation of blood glucose and the adoption of appropriate measures are critical aspects to consider for the diabetic patient in this pandemic period, especially in the patient with ongoing infection. In this article we describe the current evidence in the literature on the possible risks of side effects caused by taking antidiabetic drugs in the COVID-19 patient and the data on extra homeostasis glycemic activity useful to fight viral infection.              Peer Review History: Received 25 May 2020; Revised 8 June; Accepted 3 July, Available online 15 July 2020 Academic Editor: Essam Mohamed Eissa, Beni-Suef University, Egypt, [email protected] UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main purpose of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency. Received file:                Reviewer's Comments: Average Peer review marks at initial stage: 5.5/10 Average Peer review marks at publication stage: 7.0/10 Reviewer(s) detail: Dr. Heba M. Abd El-Azim, Damanhour University, Egypt, [email protected] Dr. George Zhu, Tehran University of Medical Sciences, Tehran, Iran, [email protected] Similar Articles: THE RELATIONSHIP BETWEEN DIABETES MELLITUS AND TUBERCULOSIS IN REVIEW OF PREVALENCE, DIAGNOSTICS AND PREVENTIO

    USE OF COLCHICINE TO COUNTERACT THE STRONG HYPERINFLAMMATORY STATE INDUCED BY SARS-COV-2

    Get PDF
    Research in present time has been focusing on finding a specific SARS-CoV-2 vaccine or antiviral, which will probably be the therapeutic goal in the fight against the virus. In the meantime, scientific evidence shows that it is possible to have effective clinical improvements of infected patients in reducing the strong hyperinflammatory state. The SARS-CoV-2 infection is divided into three stages. The most serious phase is the third one where the immune system overdrives and launches an intense attack against itself. This is called "cytokine storm" and leads to tissue damage and often to death. Stopping the cytokine storm early is definitely an effective move; since March several studies have been evaluating how this can be an important pharmacological aspect. Blocking IL-6 or IL-1 inhibitors, for example, is already known to have wide efficacy, but they are not alone in being able to block the cascade of cytokines. This is a clinical pharmacology article and demonstrates how the use of colchicine, monotherapy or in combination in all three phases of SARS-CoV-2, controls inflammation and prevents patient death. Colchicine is safe and effective for treating SARS-CoV-2 patients in preventing inflammation and lung collapse and is certainly useful as an added remedy for other drugs. The advantage is certainly its safety profile much higher than that provided by other drugs, such as corticosteroids and immunosuppressive drugs. Note is the story of hydroxychloroquine: use has been banned due to its high toxicity.                               Peer Review History: Received 25 May 2020; Revised 10 June; Accepted 6 July, Available online 15 July 2020 Academic Editor: Dr. Muhammad Zahid Iqbal, AIMST University, Malaysia, [email protected] UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main purpose of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency. Received file:                Reviewer's Comments: Average Peer review marks at initial stage: 5.5/10 Average Peer review marks at publication stage: 7.0/10 Reviewer(s) detail: Dr. Jennifer Audu-Peter, University of Jos, Nigeria, [email protected] Dr. Robert Tungadi, State University of Gorontalo, Indonesia, [email protected]

    On flavor conservation in weak interaction decays involving mixed neutrinos

    Get PDF
    In the context of quantum field theory (QFT), we compute the amplitudes of weak interaction processes such as W+e++νe W^{+} \rightarrow e^{+} + \nu_{e} and W+e++νμ W^{+} \rightarrow e^{+} + \nu_{\mu} by using different representations of flavor states for mixed neutrinos. Analyzing the short time limit of the above amplitudes, we find that the neutrino states defined in QFT as eigenstates of the flavor charges lead to results consistent with lepton charge conservation. On the contrary, the Pontecorvo flavor states produce a violation of lepton charge in the vertex, which is in contrast with what expected at tree level in the Standard Model.Comment: 15 page
    corecore