1,153 research outputs found

    Quasiphantom categories on a family of surfaces isogenous to a higher product

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    We construct exceptional collections of line bundles of maximal length 4 on S=(C×D)/GS=(C \times D)/G which is a surface isogenous to a higher product with pg=q=0p_g=q=0 where G=G(32,27)G=G(32,27) is a finite group of order 32 having number 27 in the list of Magma library. From these exceptional collections, we obtain new examples of quasiphantom categories as their orthogonal complements.Comment: 18 pages; v2 reflects the revision made during the journal publication proces

    Increased Risk of Ischemic Stroke during Sleep in Apneic Patients.

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    BACKGROUND AND PURPOSE:The literature indicates that obstructive sleep apnea (OSA) increases the risk of ischemic stroke. However, the causal relationship between OSA and ischemic stroke is not well established. This study examined whether preexisting OSA symptoms affect the onset of acute ischemic stroke. METHODS:We investigated consecutive patients who were admitted with acute ischemic stroke, using a standardized protocol including the Berlin Questionnaire on symptoms of OSA prior to stroke. The collected stroke data included the time of the stroke onset, risk factors, and etiologic subtypes. The association between preceding OSA symptoms and wake-up stroke (WUS) was assessed using multivariate logistic regression analysis. RESULTS:We identified 260 subjects with acute ischemic strokes with a definite onset time, of which 25.8% were WUS. The presence of preexisting witnessed or self-recognized sleep apnea was the only risk factor for WUS (adjusted odds ratio=2.055, 95% confidence interval=1.035-4.083, p=0.040). CONCLUSIONS:Preexisting symptoms suggestive of OSA were associated with the occurrence of WUS. This suggests that OSA contributes to ischemic stroke not only as a predisposing risk factor but also as a triggering factor. Treating OSA might therefore be beneficial in preventing stroke, particularly that occurring during sleep

    Prediction of Giant Spin Motive Force due to Rashba Spin-Orbit Coupling

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    Magnetization dynamics in a ferromagnet can induce a spin-dependent electric field through spin motive force. Spin current generated by the spin-dependent electric field can in turn modify the magnetization dynamics through spin-transfer torque. While this feedback effect is usually weak and thus ignored, we predict that in Rashba spin-orbit coupling systems with large Rashba parameter αR\alpha_{\rm R}, the coupling generates the spin-dependent electric field [\pm(\alpha_{\rm R}m_e/e\hbar) (\vhat{z}\times \partial \vec{m}/\partial t)], which can be large enough to modify the magnetization dynamics significantly. This effect should be relevant for device applications based on ultrathin magnetic layers with strong Rashba spin-orbit coupling.Comment: 4+ pages, 2 figure

    Case report: what gives the myopic tilted disc an oval appearance?

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    Background Myopic tilted disc, observed as an oval disc, has been alleged to be a funduscopic en-face manifestation of excessive optic nerve head (ONH) sloping or tilting. Here, we report the case of a myopic child showing a developing oval disc in fundus photos during axial elongation, but without progressive tilting in spectral-domain optical coherence tomography (SD-OCT) images. Case presentation By merging B-scan SD-OCT images of the ONH and macula, the curvature of the posterior pole, including both the fovea and ONH, was reconstructed and compared before and after 2 years of axial elongation. Despite the marked increase of disc ovality, the posterior polar curvature was rarely changed. The preponderance of optic disc change was induced by the shift of the temporal disc margin in the nasal direction. This shifting alone imitated an increase of tilt angle but one that was still far smaller than the required degree of tilt for ONH-tilt-based disc ovality. To clarify, we calculated the required extent of axial elongation to obtain a substantial degree of ONH tilt when considering the adjacency of the fovea and the ONH. Without a focal increase of posterior polar curvature, which is to say posterior staphyloma, such change is not possible until the axial length increases extraordinarily. Conclusion The most prominent change in the development of myopic tilted disc, which change gives it an oval appearance and imitates a tilt when measured, is actually not a tilt but rather a shift of the temporal disc margin.This work was supported by a clinical research grant-in-aid from the Seoul Medical Center (grant no. 03–2019-3). The funders had no role in study design, data collection and analysis, interpretation of data, decision to publish, or preparation of the manuscript

    Effect of spin diffusion on current generated by spin motive force

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    Spin motive force is a spin-dependent force on conduction electrons induced by magnetization dynamics. In order to examine its effects on magnetization dynamics, it is indispensable to take into account spin accumulation, spin diffusion, and spin-flip scattering since the spin motive force is in general nonuniform. We examine the effects of all these on the way the spin motive force generates the charge and spin currents in conventional situations, where the conduction electron spin relaxation dynamics is much faster than the magnetization dynamics. When the spin-dependent electric field is spatially localized, which is common in experimental situations, we find that the conservative part of the spin motive force is unable to generate the charge current due to the cancelation effect by the diffusion current. We also find that the spin current is a nonlocal function of the spin motive force and can be effectively expressed in terms of nonlocal Gilbert damping tensor. It turns out that any spin independent potential such as Coulomb potential does not affect our principal results. At the last part of this paper, we apply our theory to current-induced domain wall motion.Comment: 14 pages, 2 figures, some of important errors were corrected but we recommend to see PRB paper if one can acces

    Long-term outcomes of initially conservatively treated midshaft clavicle fractures

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    Background Recent studies about completely displaced midshaft clavicle fractures have reported that their nonunion/malunion rates were significantly higher in conservatively treated patients compared to surgically treated patients. The purpose of this study was to evaluate the factors associated with treatment decisions for midshaft clavicle fractures and also the factors that affect patient satisfaction with their treatment choice. Methods We retrospectively reviewed the records of 75 patients who had been diagnosed with a midshaft clavicle fracture and were treated conservatively at a single institution between March 1, 2013, and December 31, 2014. Their medical records were reviewed to investigate the severity of the initial vertical displacement. A telephone survey was carried out to identify the presence of any patient-perceived deformity and determine if the patient eventually underwent surgery and whether the patient would prefer surgery if the injury recurred. Results Significantly more patients with vertical displacement ≥100% (9/28) eventually underwent surgery compared to patients with vertical displacement <100% (3/32, p=0.028). Patients with vertical displacement ≥100% (13/28) were significantly more likely to prefer surgery compared to patients with vertical displacement <100% (7/32, p=0.044). Among the conservatively treated patients, nine of 32 participants with a patient-perceived deformity and one of 16 without a patient-perceived deformity responded that they would prefer to receive surgery in same situation in the future (p=0.079). Conclusions Patients with a midshaft clavicle fracture with vertical displacement of ≥100% may eventually require surgical treatment. When conservative treatment is carried out, the long-term patient results may be unsatisfactory due to perceived residual deformities

    Increased interleukin-17 production via a phosphoinositide 3-kinase/Akt and nuclear factor κB-dependent pathway in patients with rheumatoid arthritis

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    Inflammatory mediators have been recognized as being important in the pathogenesis of rheumatoid arthritis (RA). Interleukin (IL)-17 is an important regulator of immune and inflammatory responses, including the induction of proinflammatory cytokines and osteoclastic bone resorption. Evidence for the expression and proinflammatory activity of IL-17 has been demonstrated in RA synovium and in animal models of RA. Although some cytokines (IL-15 and IL-23) have been reported to regulate IL-17 production, the intracellular signaling pathways that regulate IL-17 production remain unknown. In the present study, we investigated the role of the phosphoinositide 3-kinase (PI3K)/Akt pathway in the regulation of IL-17 production in RA. Peripheral blood mononuclear cells (PBMC) from patients with RA (n = 24) were separated, then stimulated with various agents including anti-CD3, anti-CD28, phytohemagglutinin (PHA) and several inflammatory cytokines and chemokines. IL-17 levels were determined by sandwich enzyme-linked immunosorbent assay and reverse transcription–polymerase chain reaction. The production of IL-17 was significantly increased in cells treated with anti-CD3 antibody with or without anti-CD28 and PHA (P < 0.05). Among tested cytokines and chemokines, IL-15, monocyte chemoattractant protein-1 and IL-6 upregulated IL-17 production (P < 0.05), whereas tumor necrosis factor-α, IL-1β, IL-18 or transforming growth factor-β did not. IL-17 was also detected in the PBMC of patients with osteoarthritis, but their expression levels were much lower than those of RA PBMC. Anti-CD3 antibody activated the PI3K/Akt pathway; activation of this pathway resulted in a pronounced augmentation of nuclear factor κB (NF-κB) DNA-binding activity. IL-17 production by activated RA PBMC is completely or partly blocked in the presence of the NF-κB inhibitor pyrrolidine dithiocarbamate and the PI3K/Akt inhibitor wortmannin and LY294002, respectively. However, inhibition of activator protein-1 and extracellular signal-regulated kinase 1/2 did not affect IL-17 production. These results suggest that signal transduction pathways dependent on PI3K/Akt and NF-κB are involved in the overproduction of the key inflammatory cytokine IL-17 in RA
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