20 research outputs found

    Efimov effect in quantum magnets

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    Physics is said to be universal when it emerges regardless of the underlying microscopic details. A prominent example is the Efimov effect, which predicts the emergence of an infinite tower of three-body bound states obeying discrete scale invariance when the particles interact resonantly. Because of its universality and peculiarity, the Efimov effect has been the subject of extensive research in chemical, atomic, nuclear and particle physics for decades. Here we employ an anisotropic Heisenberg model to show that collective excitations in quantum magnets (magnons) also exhibit the Efimov effect. We locate anisotropy-induced two-magnon resonances, compute binding energies of three magnons and find that they fit into the universal scaling law. We propose several approaches to experimentally realize the Efimov effect in quantum magnets, where the emergent Efimov states of magnons can be observed with commonly used spectroscopic measurements. Our study thus opens up new avenues for universal few-body physics in condensed matter systems.Comment: 7 pages, 5 figures; published versio

    Shared Avatar for Hand Movement Imitation: Subjective and Behavioral Analyses

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    Virtual co-embodiment enables sharing avatars with others in virtual environments and can be applied for training motor skills by allowing teachers to share movements with learners in first-person perspective. We conducted a task where participants were asked to imitate pre-recorded hand movements of a teacher as accurately as possible. The participant’s virtual hand movements were averaged in real-time with those of the teacher (shared avatar hand). We compared their usability ratings and behavior against a controlled condition with full control of the hand (solo avatar hand). The teacher’s hand was displayed facing the same or the opposite direction as the participant’s hand. We hypothesized that using the shared avatar hand would improve imitation over using the solo hand, and the teacher’s hand presented in the same direction is better than that in the opposite direction. Subjective ratings showed that the shared hand was easier to use than the solo hand, and the teacher’s hand when presented in the same direction was easier to imitate than when presented in the opposite direction. Spatial error was less with the opposite-direction presentation than the same-direction presentation of the teacher’s hand, irrespective of movement sharing. Time delay was less when the participants used the shared hand compared to when they used the solo hand, irrespective of the teacher’s hand direction. These results suggest that sharing movements enhances usability and matching speed during movement imitation, and the same-direction presentation of the teacher’s hand improves usability while the opposite-direction presentation improves spatial accuracy of motor imitation

    Hypoglycemia after Mitral Valve Repair in Dogs

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    Hypoglycemia has not been previously reported as a postoperative complication of mitral valve repair (MVR) in dogs; however, the authors have encountered cases of hypoglycemia after MVR. This study aimed to determine the incidence of hypoglycemia in dogs after MVR and investigate its causes. Blood glucose levels were measured at multiple timepoints in dogs undergoing MVR. Simultaneously, insulin and glucagon blood concentrations in dogs with hypoglycemia preoperatively and postoperatively were compared to verify the physiological responses to hypoglycemia. Furthermore, risk factors for hypoglycemia, using variables selected based on the characteristics of MVR and dogs undergoing MVR, were examined prospectively. The incidence of hypoglycemia after MVR was 14.2%, and plasma glucagon concentrations increased in these dogs (mean: 260 pg/mL and 644 pg/mL pre- and postoperatively, p p = 0.002). Therefore, hyperinsulinemia or hypoglucagonemia is unlikely to be the cause of postoperative hypoglycemia. The identified risk factors for hypoglycemia included low body weight and asymptomatic myxomatous mitral valve disease. Monitoring blood glucose levels after MVR should be included in the standard hospitalization plan to prevent hypoglycemic emergencies in dogs

    Psychological disturbances and their association with sleep disturbances in patients admitted for cardiovascular diseases.

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    BackgroundDepression and anxiety are common mental health problems that are strongly associated with sleep disturbances, according to community-based researches. However, this association has not been investigated among patients admitted for cardiovascular diseases (CVDs). We examined the prevalence of depression and anxiety in inpatients with various CVDs and their association with sleep disturbances.Materials and methodsThis cross-sectional study included 1294 patients hospitalized for CVDs in a Japanese university hospital were evaluated for their mental status using the Hospital Anxiety and Depression Scale (HADS), for sleep-disordered breathing (SDB) using pulse oximetry, and for sleep quality using the Pittsburgh Sleep Quality Index (PSQI).ResultsPatient characteristics were as below: mean age, 63.9±14.7 years; 25.7% female. Overall, 18.9% had depression (HADS-depression≥8) and 17.1% had anxiety (HADS-anxiety≥8). The presence of depression was associated with female sex, older age, higher plasma brain natriuretic peptide level, lower estimated glomerular filtration rate, and the prevalence of heart failure. Overall, 46.5% patients were categorized as having a poor sleep quality (PSQI>5), and 28.5% patients had SDB (3% oxygen desaturation index>15). Although depression and anxiety were not associated with SDB, they were independently associated with poor sleep quality (OR = 3.09, 95% CI 2.19-4.36; OR = 3.93, 95% CI 2.71-5.69, respectively).ConclusionsDepression and anxiety were not uncommon in patients with CVDs. Poor sleep quality could be an important risk factor linked to psychological disturbances

    Long-term survival in Japanese renal transplant recipients with Alport syndrome: a retrospective study

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    Abstract Background Patients with Alport syndrome (AS) develop progressive kidney dysfunction due to a hereditary type IV collagen deficiency. Survival of the kidney allograft in patients with AS is reportedly excellent because AS does not recur. However, several studies have implied that the type IV collagen in the GBM originates from podocytes recruited from the recipient’s bone marrow-derived cells, suggesting the possibility of AS recurrence. Limited data are available regarding AS recurrence and graft survival in the Japanese population; the vast majority were obtained from living related kidney transplantation (LRKTx). Methods In this retrospective study, twenty-one patients with AS were compared with 41 matched patients without AS from 1984 to 2015 at two centers using propensity scores. Nineteen of the 21 patients with AS underwent LRKTx. The mean post-transplant follow-up period was 83 months in the AS group and 110 months in the control group. Histopathological AS recurrence was assessed by immunoreactivity of α5 (type IV collagen) antibody and electron microscopy. Results The graft survival rate was equivalent between patients with and without AS (86.7% vs. 77.1% and 69.3% vs. 64.2% at 5 and 10 years; p = 0.16, log-rank test). Immunoreactivity to α5 antibody showed strong linear positivity with no focal defect in six patients. Electron microscopy showed no GBM abnormalities in two patients who were exhibiting long-term kidney allograft survival. Conclusions We confirmed that α5 and the GBM structure were histopathologically maintained in the long term after kidney transplantation. The patient and graft survival rates were equivalent between Japanese patients with and without AS

    Successful treatment of recurrent immunoglobulin a nephropathy using steroid pulse therapy plus tonsillectomy 10 years after kidney transplantation: a case presentation

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    Abstract Background Both prevention and treatment of recurrent immunoglobulin A nephropathy (IgAN) in kidney transplant recipients are important since recurrent IgAN seems to affect long-term graft survival. We present here a case of recurrent IgAN that was successfully treated using steroid pulse therapy plus tonsillectomy 10 years after kidney transplantation. Case presentation A 46-year-old male was admitted for an episode biopsy with a serum creatinine level of 1.8 mg/dl and proteinuria (0.7 g/day). Histological features showed recurrent IgAN (only focal segmental mesangial proliferation) and severe arteriolar hyalinosis partly associated with calcineurin inhibitor toxicity, with limited interstitial fibrosis and tubular atrophy (5%) (IF/TA) 8 years after transplantation. Sodium restriction and conversion from cyclosporine to tacrolimus successfully reduced his proteinuria to the level of 0.15 g/day. However, 2 years later, his proteinuria increased again (1.0 g/day) and a second episode biopsy showed global mesangial proliferation with glomerular endocapillary and extracapillary proliferation accompanied by progressive IF/TA (20%). The steroid pulse therapy plus tonsillectomy successfully decreased his proteinuria and he achieved clinical remission 3 years after this treatment. Conclusion This case, presented with a review of relevant literature, demonstrates the difficulty and importance of the treatment of recurrent IgAN and calcineurin inhibitor arteriolopathy, especially in long-term kidney allograft management

    Successful Treatment of Plasma Cell-Rich Acute Rejection Using Pulse Steroid Therapy Alone: A Case Report

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    Despite the recent development of immunosuppressive agents, plasma cell-rich acute rejection (PCAR) has remained refractory to treatment. Herein, we report an unusual case of PCAR that responded well to pulse steroid therapy alone. A 47-year-old man was admitted for a protocol biopsy three months after kidney transplantation, with a stable serum creatinine level of 1.6 mg/dL. Histological examination showed focal aggressive tubulointerstitial inflammatory cell infiltration of predominantly polyclonal mature plasma cells, leading to our diagnosis of PCAR. Three months following three consecutive days of high-dose methylprednisolone (mPSL) therapy, an allograft biopsy performed for therapy evaluation showed persistent PCAR. We readministered mPSL therapy and successfully resolved the PCAR. Although PCAR generally develops more than six months after transplantation, we diagnosed this case early, at three months after transplantation, with focally infiltrated PCAR. This case demonstrates the importance of early diagnosis and prompt treatment of PCAR to manage the development and severity of allograft rejection

    プライオメトリックトレーニングが試合期の大学女子バレーボール選手におけるジャンプ能力に及ぼす影響

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     To investigate the effects of plyometric training on the jumping ability of volleyball players during the playing season, 20 female intercollegiate volleyballers participated in this study. Thirteen players (training group: TG) performed a program consisting of plyometric training with stretch-shorting cycle exercise during the playing season, together with volleyball practice, while the remaining 7 players (control group: CG) conducted the volleyball practice only. Fitness tests (jumping height, shuttle running, muscle thickness, and subcutaneous fat thickness) of both groups were done before (Pre-test) and after (Post-test) during the playing season. In the TG, jumping height (during jumping with reaction, spike jumping and block jumping), time of 18-m shuttle running (as index of agility), muscle thickness of tibialis anterior and posteriorleg improved significantly from Pre-test to Post-test. However, no significant changes were observed in subcutaneous fat thickness. There were significant decreases in jumping height (during both jumping with and without reaction, and spike jumping) and increases of subcutaneous fat thickness (on quadriceps femoris and rectus abdominus) in the CG from Pre-test to Post-test. Moreover, there were no significant changes in time of 6-m, 12-m and 18-m shuttle run and muscle thickness in the CG. These results suggest that plyometric training in female volleyballers prevents the decrease of jumping ability during the playing season and increases of muscle thickness with no change of fatness

    屋内・屋外におけるスポーツ活動現場の温熱的環境

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     We compared wet-bulb globe temperature (WBGT) as an integrated index of the thermal environment in outdoor and indoor sports activities. Measurements of globe temperature, relative humidity and air temperature for calculating WBGT were made every 30 minutes during the practice of women’s softball and volleyball teams at Osaka Int’l University from April to November. There were no significant group differences in WBGT between indoor and outdoor sports activities from the beginning of July to the middle of September. However, the globe temperature (during July - September) and air temperature (during August) were significantly higher outdoors than indoors. The relative humidity (during July and August) was significantly higher indoors than outdoors. These results suggest that countermeasures against the increases of humidity during indoor sports activity and of solar radiation during outdoor sports activity should be taken to prevent heat disorders
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