504 research outputs found

    Ballistic transport in one-dimensional loops with Rashba and Dresselhaus spin-orbit coupling

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    We discuss the combined effect of Rashba and Dresselhaus spin-orbit interactions in polygonal loops formed by quantum wires, when the electron are injected in a node and collected at the opposite one. The conditions that allow perfect localization are found. Furthermore, we investigate the suppression of the Al'tshuler--Aronov--Spivak oscillations that appear, in presence of a magnetic flux, when the electrons are injected and collected at the same node. Finally, we point out that a recent realization of a ballistic spin interferometer can be used to obtain a reliable estimate of the magnitude ratio of the two spin-orbit interactions.\bigski

    Charge and heat transport in soft nanosystems in the presence of time-dependent perturbations

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    Soft nanosystems are electronic nanodevices, such as suspended carbon nanotubes or molecular junctions, whose transport properties are modulated by soft internal degrees of freedom, for example slow vibrational modes. Effects of the electron-vibration coupling on the charge and heat transport of soft nanoscopic systems are theoretically investigated in the presence of time-dependent perturbations, such as a forcing antenna or pumping terms between the leads and the nanosystem. A well-established approach valid for non-equilibrium adiabatic regimes is generalized to the case where external time-dependent perturbations are present. Then, a number of relevant applications of the method are reviewed for systems composed by a quantum dot (or molecule) described by a single electronic level coupled to a vibrational mode

    Rashba effect induced localization in quantum networks

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    We study a quantum network extending in one-dimension (chain of square loops connected at one vertex) made up of quantum wires with Rashba spin-orbit coupling. We show that the Rashba effect may give rise to an electron localization phenomenon similar to the one induced by magnetic field. This localization effect can be attributed to the spin precession due to the Rashba effect. We present results both for the spectral properties of the infinite chain, and for linear transport through a finite-size chain connected to leads. Furthermore, we study the effect of disorder on the transport properties of this network.Comment: To appear in Phys. Rev. Let

    Rashba effect in quantum networks

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    We present a formalism to study quantum networks made up by single-channel quantum wires in the presence of Rashba spin-orbit coupling and magnetic field. In particular, linear transport through one-dimensional and two-dimensional finite-size networks is studied by means of the scattering formalism. In some particular quantum networks, the action of the magnetic field or of the Rashba spin-orbit coupling induces localization of the electron wave function. This phenomenon, which relies on both the quantum-mechanical interference and the geometry of the network, is manifested through the suppression of the conductance for specific values of the spin-orbit-coupling strength or of the magnetic field. Furthermore, the interplay of the Aharonov-Bohm phases and of the non-Abelian phases introduced by spin-orbit coupling, is discussed in a number of cases.Comment: 8 pages and 6 figure

    Secreted miR-210-3p as non-invasive biomarker in clear cell renal cell carcinoma

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    The most common subtype of renal cell carcinoma (RCC) is clear cell RCC (ccRCC). It accounts for 70-80% of all renal malignancies representing the third most common urological cancer after prostate and bladder cancer. The identification of non-invasive biomarkers for the diagnosis and responsiveness to therapy of ccRCC may represent a relevant step-forward in ccRCC management. The aim of this study is to evaluate whether specific miRNAs deregulated in ccRCC tissues present altered levels also in urine specimens. To this end we first assessed that miR-21-5p, miR-210-3p and miR-221-3p resulted upregulated in ccRCC fresh frozen tissues compared to matched normal counterparts. Next, we evidenced that miR-210-3p resulted significantly upregulated in 38 urine specimens collected from two independent cohorts of ccRCC patients at the time of surgery compared to healthy donors samples. Of note, miR- 210-3p levels resulted significantly reduced in follow-up samples. These results point to miR-210-3p as a potential non-invasive biomarker useful not only for diagnosis but also for the assessment of complete resection or response to treatment in ccRCC management

    Montelukast therapy and psychological distress in chronic obstructive pulmonary disease (COPD): a preliminary report

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    Chronic obstructive pulmonary disease (COPD) is an alteration in which ventilatory function, exercise capacity and health status of patients progressively decline and it is characterized by an increase of inflammatory cytokines such as TNF-a, LTB4, IL-8, etc. In this study we considered twenty patients (15 males and 5 females; mean age: 72.8 6.3) with stable COPD. All patients were performed evaluation of psychological stress at enrollment and were treated with leukotriene receptor antagonists (montelukast tablets) 10 mg/day for 12 months. After 12 months we observed a significant decrease of serum levels of LTB4, IL-8 and also a decrease of the number of outpatient clinic visits, of the number of hospitalizations and of the duration of hospitalizatio

    New frontiers of cognitive rehabilitation in geriatric age: the Mozart effect (ME)

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    The ME was described for the first time in 1993. Subsequently other studies with similar designs were performed. The present study, therefore, proposes: (i) to verify the existence of the benefits of exposure to music in elderly subjects with mild cognitive impairment (MCI), (ii) to explore whether it is possible to find any lasting improvement after training, conducted for a long period of time, with such musical pieces, in the measurable cognitive performances. The study we conducted showed that the ME is present in geriatric patients with MCI; the influence on spatial–temporal abilities remains constant in time if the stimulation is maintained. The continuation of our study will consist of increasing the number of individuals examined and in having them listen to music during the study of ECG rhythms and during the acquisition of cerebral functional magnetic resonance imaging (fMRI), and, at the same time, testing them by neuropsychometric methods

    Distribution pattern of hepatitis C virus genotypes and correlation with viral load and risk factors in chronic positive patients.

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    Objective: Hepatitis C virus (HCV) has emerged as a leading cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma worldwide. The purpose of this study was to describe the distribution pattern of HCV genotypes in chronic hepatitis patients in the Campania region of southern Italy and estimate their association with risk factors and viral load. Materials and Methods: 404 consecutive HCV ribonucleic acid-positive patients were included in the study. HCV genotyping was carried out by the HCV line probe assay test and viral load estimation by the TaqMan real-time PCR system. Results: The predominant genotype was 1 (63.6%), followed by genotype 2 (29.4%), 3 (6.2%) and 4 (0.8%). Subtype 1b was more frequent in females than in males. Conversely, genotype 3 was more frequent in males. No significant difference was observed in age distribution of HCV genotypes. Surgery and dental therapy were the most frequent risk factors for genotype 1 and intravenous drug abuse and tattooing for genotype 3. Patients with genotype 1 more frequently showed high HCV viral load when compared to those with genotypes 2 and 3. Conclusion: The present study revealed that HCV genotypes 1 and 2 accounted for over 95% of all HCV infections in the Campania region, and genotype 1 was more frequently associated with a higher viral load when compared to genotypes 2 and 3

    Beta-Blocker Use in Older Hospitalized Patients Affected by Heart Failure and Chronic Obstructive Pulmonary Disease: An Italian Survey From the REPOSI Register

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    Beta (β)-blockers (BB) are useful in reducing morbidity and mortality in patients with heart failure (HF) and concomitant chronic obstructive pulmonary disease (COPD). Nevertheless, the use of BBs could induce bronchoconstriction due to β2-blockade. For this reason, both the ESC and GOLD guidelines strongly suggest the use of selective β1-BB in patients with HF and COPD. However, low adherence to guidelines was observed in multiple clinical settings. The aim of the study was to investigate the BBs use in older patients affected by HF and COPD, recorded in the REPOSI register. Of 942 patients affected by HF, 47.1% were treated with BBs. The use of BBs was significantly lower in patients with HF and COPD than in patients affected by HF alone, both at admission and at discharge (admission, 36.9% vs. 51.3%; discharge, 38.0% vs. 51.7%). In addition, no further BB users were found at discharge. The probability to being treated with a BB was significantly lower in patients with HF also affected by COPD (adj. OR, 95% CI: 0.50, 0.37-0.67), while the diagnosis of COPD was not associated with the choice of selective β1-BB (adj. OR, 95% CI: 1.33, 0.76-2.34). Despite clear recommendations by clinical guidelines, a significant underuse of BBs was also observed after hospital discharge. In COPD affected patients, physicians unreasonably reject BBs use, rather than choosing a β1-BB. The expected improvement of the BB prescriptions after hospitalization was not observed. A multidisciplinary approach among hospital physicians, general practitioners, and pharmacologists should be carried out for better drug management and adherence to guideline recommendations
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