Spin currents in rough graphene nanoribbons: Universal fluctuations and spin injection

We investigate spin conductance in zigzag graphene nanoribbons and propose a spin injection mechanism based only on graphitic nanostructures. We find that nanoribbons with atomically straight, symmetric edges show zero spin conductance, but nonzero spin Hall conductance. Only nanoribbons with asymmetrically shaped edges give rise to a finite spin conductance and can be used for spin injection into graphene. Furthermore, nanoribbons with rough edges exhibit mesoscopic spin conductance fluctuations with a universal value of $\mathrm{rms} G_\mathrm{s}\approx 0.4 e/4\pi$.Comment: 4 pages, 5 figures, PdfLaTeX, accepted for publication in Physical Review Letter

Chirality blockade of Andreev reflection in a magnetic Weyl semimetal

A Weyl semimetal with broken time-reversal symmetry has a minimum of two species of Weyl fermions, distinguished by their opposite chirality, in a pair of Weyl cones at opposite momenta $\pm K$ that are displaced in the direction of the magnetization. Andreev reflection at the interface between a Weyl semimetal in the normal state (N) and a superconductor (S) that pairs $\pm K$ must involve a switch of chirality, otherwise it is blocked. We show that this "chirality blockade" suppresses the superconducting proximity effect when the magnetization lies in the plane of the NS interface. A Zeeman field at the interface can provide the necessary chirality switch and activate Andreev reflection.Comment: 15 pages, 9 figures. V2: added investigation of the dependence of the chirality blockade on the direction of the magnetization and (Appendix C) calculations of the Fermi-arc mediated Josephson effec

Edge effects in graphene nanostructures: I. From multiple reflection expansion to density of states

We study the influence of different edge types on the electronic density of states of graphene nanostructures. To this end we develop an exact expansion for the single particle Green's function of ballistic graphene structures in terms of multiple reflections from the system boundary, that allows for a natural treatment of edge effects. We first apply this formalism to calculate the average density of states of graphene billiards. While the leading term in the corresponding Weyl expansion is proportional to the billiard area, we find that the contribution that usually scales with the total length of the system boundary differs significantly from what one finds in semiconductor-based, Schr\"odinger type billiards: The latter term vanishes for armchair and infinite mass edges and is proportional to the zigzag edge length, highlighting the prominent role of zigzag edges in graphene. We then compute analytical expressions for the density of states oscillations and energy levels within a trajectory based semiclassical approach. We derive a Dirac version of Gutzwiller's trace formula for classically chaotic graphene billiards and further obtain semiclassical trace formulae for the density of states oscillations in regular graphene cavities. We find that edge dependent interference of pseudospins in graphene crucially affects the quantum spectrum.Comment: to be published in Phys. Rev.

Anisotropic universal conductance fluctuations in disordered quantum wires with Rashba and Dresselhaus spin-orbit interaction and applied in-plane magnetic field

We investigate the transport properties of narrow quantum wires realized in disordered two-dimensional electron gases in the presence of k-linear Rashba and Dresselhaus spin-orbit interaction (SOI), and an applied in-plane magnetic field. Building on previous work [Scheid, et al., PRL 101, 266401 (2008)], we find that in addition to the conductance, the universal conductance fluctuations also feature anisotropy with respect to the magnetic field direction. This anisotropy can be explained solely from the symmetries exhibited by the Hamiltonian as well as the relative strengths of the Rashba and Dresselhaus spin orbit interaction and thus can be utilized to detect this ratio from purely electrical measurements.Comment: 10 pages, 4 figures, 1 tabl

Does the impact of COVID-19 on patients with systemic sclerosis change over time?

ObjectiveThe outcome of patients with COVID-19 improved over the pandemic, including patients with systemic rheumatic diseases. However, data on patients with systemic sclerosis (SSc) are lacking. This study aimed to assess the outcome of patients with both SSc and COVID-19 over several waves.MethodsPatients with both SSc and COVID-19 who were registered in the European Scleroderma Trials and Research group (EUSTAR) were collected between April 2020 and April 2021. Patients were assigned to waves 1, 2, or 3 depending on the date of their COVID-19 diagnosis. Primary endpoints were death, intensive care unit stay, or ventilatory support (severe outcome). Subgroup analyses of patients who were hospitalized or died were conducted. General and SSc-specific characteristics and treatment were compared over the waves. Descriptive statistics and multivariate logistic regression were applied.ResultsA total of 333 patients were included; 57 patients (17%) had a severe outcome, and 30 patients (9%) died. Compared to wave 1, significantly fewer patients with SSc suffered from severe COVID-19 in waves 2 and 3 (28.2% vs 9.8% and 12.7%; P P P = 0.001), and fewer patients died (15.7% vs 5.0% and 7.5%; P = 0.011). Patients were significantly younger, more often men, had less frequent arterial hypertension, and less SSc cardiac involvement over waves 1 to 3. Patients received significantly less medium to high doses of corticosteroids as they did SSc treatment.ConclusionThe outcome of patients with both SSc and COVID-19 improved significantly over time because of intrinsic and extrinsic factors.Pathophysiology and treatment of rheumatic disease

Vanadium and its interaction with diabetes [Vanadyum ve diyabetle etkileşimi]

Vanadium was first discovered in 1813 by the Spanish mineralogist del Rio, who gave it the name "panchromium" because of its color changes when passing through various oxidation states. It was rediscovered in 1831 by the Swedish chemist Nils Gabriel Sefstrom, who named the compound Vanadis, a nickname of the Germanic beauty, youth and lustre symbol. In humans, the total body pool of vanadium is estimated to be around 100-200 µg. In common with most transitional metals, vanadium exists in several valence states. In biological systems vanadium is found predominantly as vanadate (+5) and vanadyl (+4) forms. In the plasma, vanadium exists in both oxidation states. Approximately 90% is bound to proteins, predominantly transferrin. Most ingested vanadium is transformed in the stomach to cationic vanadile and remains in this form as it passes through the duodenum. Vanadium is preferentially distributed in the bone, kidney and liver following intraperitoneal injection; the bone representing the main storage depot for vanadium. Vanadium affects various aspects of carbohydrate metabolism including glucose transport, glucose transporter translocation, glycolysis and glycolitic enzymes, glucose oxidation, glucose output and glycogen synthesis. The insulin-like effects of vanadium also extend to the lipid metabolic pathways and on protein metabolism and mitogenesis. Despite the availability of insulin and a host of oral hypoglycemic drugs, diabetes still remains a major health concern for humans. Therefore, new therapeutic approaches are needed to treat diabetes more efficiently. In this regard, studies have demonstrated that the trace element vanadium exert various insulinomimetic and antidiabetic effects in vivo and in vitro. The exact cellular mechanism of action of vanadium appears to involve a combination of several post-receptor events in the insulin-signaling cascade. In the current review, the history of vanadium and its interaction with diabetes, proposed mechanisms of action and related studies were attempted to be summarized

Recognition of Daily and Sports Activities

Baidu;et al.;Expedia Group;IEEE;IEEE Computer Society;Squirrel AI Learning2018 IEEE International Conference on Big Data, Big Data 2018Since being physically inactive was reported as one of the major risk factor of mortality, classifying daily and sports activities becomes a critical task that may improve human life quality. In this paper, the daily and sports activities dataset was used in order to evaluate and validate the employed approach. In this approach, the statistical features were extracted from the histograms of the local changes in the wearable sensors logs were obtained by one-dimensional local binary patterns. Later, extracted features were classified by extreme learning machines. Results were showed that the proposed approach is enough to recognize the action type, but in order to recognize the actions, or gender, different feature extraction methods must be employed. © 2018 IEEE

Novel and known periodontal pathogens residing in gingival crevicular fluid are associated with rheumatoid arthritis

Background Periodontitis is a suspected environmental risk factor for the development of rheumatoid arthritis (RA). However, correlation mechanisms between the two pathologies remain elusive. This study examined potential correlations between detached subgingival bacteria collected in gingival crevicular fluid (GCF) and RA parameters. Methods RA patients (n = 52, F:M = 40:12), patients with Behcet's disease (BD,n = 40, F:M = 29:11) as another systemic inflammatory disease were studied along with a systemically healthy control group (HC,n = 57, F:M = 40:17). All participants were non-smokers. Full mouth periodontal parameters were recorded. RA activity was assessed using the 28-joint Disease Activity Score (DAS-28). Rheumatoid factors (RFs)-IgM and -IgA were measured by ELISA. GCF samples were investigated by means of fluorescent in situ hybridization for 10 different bacterial taxa. Results The taxa TM7,Synergistetescluster B,Leptotrichia, Megasphaera,Anaeroglobus geminatus, andTannerella forsythiadisplayed significantly differential abundances between the groups. Whereas abundances ofMegasphaeraandA. geminatuswere significantly increased in the RA group, onlyPorphyromonas gingivalisdisplayed significant correlations with plaque scores, bleeding on probing, and RF-IgA. RA patients displaying RF-IgA levels >75 IU/mL exhibited five-fold more abundantP. gingivalislevels than patients below the threshold. This association with RF-IgA levels appeared even more pronounced, by six-fold moreP. gingivalis(P = 0.025), in patients with a DAS-28 score >3.2, indicative of moderate/very active RA. Conclusions Unattached GCF bacteria may mediate the association between periodontitis and RA, and monitoring the bacterial composition of GCF might inform on RA activity. The role of newly identified bacterial taxa in RA warrants further investigations.Janggen-Pohn Foundation, St-Gallen, Switzerland ; Karolinska Institutet Strategic Funds, Sweden ; University of Zurich Institutional Funds, Switzerlan