985 research outputs found

    A Pilot Study: The Beneficial Effects of Combined Statin-exercise Therapy on Cognitive Function in Patients with Coronary Artery Disease and Mild Cognitive Decline.

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    Objective Hypercholesterolemia, a risk factor in cognitive impairment, can be treated with statins. However, cognitive decline associated with "statins" (HMG-CoA reductase inhibitors) is a clinical concern. This pilot study investigated the effects of combining statins and regular exercise on cognitive function in coronary artery disease (CAD) patients with prior mild cognitive decline. Methods We recruited 43 consecutive CAD patients with mild cognitive decline. These patients were treated with a statin and weekly in-hospital aerobic exercise for 5 months. We measured serum lipids, exercise capacity, and cognitive function using the mini mental state examination (MMSE). Results Low-density lipoprotein cholesterol levels were significantly decreased, and maximum exercise capacity (workload) was significantly increased in patients with CAD and mild cognitive decline after treatment compared with before. Combined statin-exercise therapy significantly increased the median (range) MMSE score from 24 (22-25) to 25 (23-27) across the cohort (p<0.01). Changes in body mass index (BMI) were significantly and negatively correlated with changes in the MMSE. After treatment, MMSE scores in the subgroup of patients that showed a decrease in BMI were significantly improved, but not in the BMI-increased subgroup. Furthermore, the patients already on a statin at the beginning of the trial displayed a more significant improvement in MMSE score than statin-naïve patients, implying that exercise might be the beneficial aspect of this intervention as regards cognition. In a multivariate logistic regression analysis adjusted for age >65 years, sex, and presence of diabetes mellitus, a decrease in BMI during statin-exercise therapy was significantly correlated with an increase in the MMSE score (odds ratio: 4.57, 95% confidence interval: 1.05-20.0; p<0.05). Conclusion Statin-exercise therapy may help improve cognitive dysfunction in patients with CAD and pre-existing mild cognitive decline

    Electronic structure reconstruction by orbital symmetry breaking in IrTe2

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    We report an angle-resolved photoemission spectroscopy (ARPES) study on IrTe2 which exhibits an interesting lattice distortion below 270 K and becomes triangular lattice superconductors by suppressing the distortion via chemical substitution or intercalation. ARPES results at 300 K show multi-band Fermi surfaces with six-fold symmetry which are basically consistent with band structure calculations. At 20 K in the distorted phase, whereas the flower shape of the outermost Fermi surface does not change from that at 300 K, topology of the inner Fermi surfaces is strongly modified by the lattice distortion. The Fermi surface reconstruction by the distortion depends on the orbital character of the Fermi surfaces, suggesting importance of Ir 5d and/or Te 5p orbital symmetry breaking.Comment: 4pages, 4figure

    Important Roles of Te 5p and Ir 5d Spin-orbit Interactions on the Multi-band Electronic Structure of Triangular Lattice Superconductor Ir1-xPtxTe2

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    We report an angle-resolved photoemission spectroscopy (ARPES) study on a triangular lattice superconductor Ir1−x_{1-x}Ptx_{x}Te2_2 in which the Ir-Ir or Te-Te bond formation, the band Jahn-Teller effect, and the spin-orbit interaction are cooperating and competing with one another. The Fermi surfaces of the substituted system are qualitatively similar to the band structure calculations for the undistorted IrTe2_2 with an upward chemical potential shift due to electron doping. A combination of the ARPES and the band structure calculations indicates that the Te 5p5p spin-orbit interaction removes the px/pyp_x/p_y orbital degeneracy and induces px±ipyp_x \pm ip_y type spin-orbit coupling near the A point. The inner and outer Fermi surfaces are entangled by the Te 5p5p and Ir 5d5d spin-orbit interactions which may provide exotic superconductivity with singlet-triplet mixing.Comment: 10 pages, 4 figure

    Competition between spin ordering and superconductivity near the pseudogap boundary in La2−xSrxCuO4: Insights from NMR

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    When superconductivity is suppressed by high magnetic fields in La2−xSrxCuO4, striped antiferromagnetic (AFM) order becomes the magnetic ground state of the entire pseudogap regime, up to its end at the doping p∗ [Frachet, Vinograd et al., Nat. Phys. 16, 1064 (2020)]. Glass-like freezing of this state is detected in 139La NMR measurements of the spin-lattice relaxation rate T−11. Here, we present a quantitative analysis of T−11 data in the hole-doping range p=x=0.12−0.171, based on the Bloembergen-Purcell-Pound (BPP) theory, modified to include statistical distribution of parameters arising from strong spatial inhomogeneity. We observe spin fluctuations to slow down at temperatures T near the onset of static charge order and, overall, the effect of the field B may be seen as equivalent to strengthening stripe order by approaching p=0.12 doping. In details, however, our analysis reveals significant departure from usual field-induced magnetic transitions. The continuous growth of the amplitude of the fluctuating moment with increasing B suggests a nearly-critical state in the B→0 limit, with very weak quasistatic moments possibly confined in small areas like vortex cores. Further, the nucleation of spin order in the vortex cores is shown to account quantitatively for both the value and the p dependence of a field scale characterizing bulk spin freezing. The correlation time of the fluctuating moment appears to depend exponentially on B/T (over the investigated range). This explains the timescale dependence of various experimental manifestations, including why, for transport measurements, the AFM moments may be considered static over a considerable range of B and T. These results make the high-field magnetic ground state up to p∗ an integral part of the discussion on putative quantum criticality

    Three-Dimensional Fermi Surface of Overdoped La-Based Cuprates

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    We present a soft x-ray angle-resolved photoemission spectroscopy study of the overdoped high-temperature superconductors La2−x_{2-x}Srx_xCuO4_4 and La1.8−x_{1.8-x}Eu0.2_{0.2}Srx_xCuO4_4. In-plane and out-of-plane components of the Fermi surface are mapped by varying the photoemission angle and the incident photon energy. No kzk_z dispersion is observed along the nodal direction, whereas a significant antinodal kzk_z dispersion is identified. Based on a tight-binding parametrization, we discuss the implications for the density of states near the van-Hove singularity. Our results suggest that the large electronic specific heat found in overdoped La2−x_{2-x}Srx_xCuO4_4 can not be assigned to the van-Hove singularity alone. We therefore propose quantum criticality induced by a collapsing pseudogap phase as a plausible explanation for observed enhancement of electronic specific heat
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