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result(s) for
"Kamitani, M."
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Switching of band inversion and topological surface states by charge density wave
by
Kumigashira, H.
,
Ishiwata, S.
,
Sugita, Y.
in
639/301/119/995
,
639/766/119/2792/4128
,
Brillouin zones
2020
Topologically nontrivial materials host protected edge states associated with the bulk band inversion through the bulk-edge correspondence. Manipulating such edge states is highly desired for developing new functions and devices practically using their dissipation-less nature and spin-momentum locking. Here we introduce a transition-metal dichalcogenide VTe
2
, that hosts a charge density wave (CDW) coupled with the band inversion involving V3
d
and Te5
p
orbitals. Spin- and angle-resolved photoemission spectroscopy with first-principles calculations reveal the huge anisotropic modification of the bulk electronic structure by the CDW formation, accompanying the selective disappearance of Dirac-type spin-polarized topological surface states that exist in the normal state. Thorough three dimensional investigation of bulk states indicates that the corresponding band inversion at the Brillouin zone boundary dissolves upon the CDW formation, by transforming into anomalous flat bands. Our finding provides a new insight to the topological manipulation of matters by utilizing CDWs’ flexible characters to external stimuli.
Manipulating topological states by coupled electronic orders is promising for future dissipation-less electronic devices. Here, Mitsuishi et al. report selective vanishing of Dirac-type topological surface states by the formation of coupled charge density wave in a transition-metal dichalcogenide VTe
2
.
Journal Article
Usefulness of High-Sensitivity Cardiac Troponin T and Brain Natriuretic Peptide as Biomarkers of Myocardial Fibrosis in Patients With Hypertrophic Cardiomyopathy
by
Miki, Shigeyuki
,
Harimoto, Kuniyasu
,
Kawasaki, Tatsuya
in
Aged
,
Biomarkers - blood
,
Cardiology
2013
Myocardial fibrosis assessed by late gadolinium enhancement cardiac magnetic resonance imaging is associated with cardiovascular events in patients with hypertrophic cardiomyopathy (HC), but few data are available regarding the utility of biomarkers for detecting late gadolinium enhancement. The aim of this study was to examine serum levels of myoglobin, cardiac myosin light chain I, high-sensitivity cardiac troponin T (hs-cTnT), and creatine kinase-MB isoenzyme and plasma levels of brain natriuretic peptide (BNP) in relation to late gadolinium enhancement in 53 patients with HC. Levels of hs-cTnT and BNP were higher in 23 patients with late gadolinium enhancement than in 30 patients without it (p <0.01 for both). An hs-cTnT level ≥0.007 ng/ml or a BNP level ≥70 pg/ml had good diagnostic value for detecting late gadolinium enhancement, with sensitivity of 96% or specificity of 90% with the combination of these 2 biomarkers. The extent of late gadolinium enhancement was correlated with BNP level (p <0.01) but not with hs-cTnT level in 23 patients with HC with late gadolinium enhancement. The increase in the extent of late gadolinium enhancement was related to hs-cTnT level in 8 patients during 22 months of follow-up (p = 0.02). In conclusion, the combination of hs-cTnT and BNP is useful in detecting myocardial fibrosis in patients with HC. The findings of this study indicate that hs-cTnT is a direct marker of ongoing myocardial fibrosis and that BNP is a marker of left ventricular overload partially associated with myocardial fibrosis.
Journal Article
Effects of combination therapy with mitiglinide and voglibose on postprandial plasma glucose in patients with type 2 diabetes mellitus
by
Hamaguchi, Tomoya
,
Namba, Mitsuyoshi
,
Tsunoda, Taku
in
Carbohydrates
,
Cardiovascular diseases
,
Combination therapy
2013
Patients with diabetes mellitus are at increased risk from cardiovascular-related morbidity and mortality as compared with healthy individuals. An association between the postprandial metabolic state and atherogenesis has been observed in patients with diabetes mellitus. In the Study to Prevent Non-Insulin-Dependent Diabetes Mellitus (STOP-NIDDM), treatment with an α-glucosidase inhibitor (α-GI) in patients with impaired glucose tolerance not only reduced the rate of conversion from impaired glucose tolerance to type 2 diabetes mellitus (T2DM), but was also associated with a reduction in the risk of cardiovascular events. These results suggested the importance of treating postprandial hyperglycemia in the early stages of T2DM. Glinides are rapid and short-acting insulin secretagogues that bind to the sulfonylurea receptors on pancreatic β-cells to facilitate rapid insulin secretion, restore postprandial early insulin secretion, and reduce the postprandial glucose spike. Moreover, α-GIs reduce postprandial hyperglycemia and insulin secretion by delaying the digestion of carbohydrates and polysaccharides in the small intestine. Then, both glinides and α-GI have beneficial effects for treating patients with T2DM and impaired glucose tolerance. Considering the ameliorating effects of these drugs on postprandial metabolic disorders, combinations of glinides and α-GI might constitute a promising therapeutic strategy for managing patients with T2DM, and also appear to be suitable for Japanese people, who consume more carbohydrates, such as polished rice, than Caucasians. It has recently been reported that combined use of mitiglinide and voglibose reduces postprandial insulin secretion and blunts diurnal glycemic changes in T2DM patients. This therapy can thus be regarded as being suitable for achieving strict postprandial glycemic control. In this report, we outline the effects of this combination therapy on postprandial plasma glucose and assess its safety.
Journal Article
The necessity of lumbar puncture in adult emergency patients with fever-associated seizures
by
Fujiwara, Satoru
,
Mizu, Daisuke
,
Huh, Ji-Young
in
Adult patients
,
Blood tests
,
C-reactive protein
2022
Central nervous system (CNS) infections are often suspected in adult patients with fever-associated seizures. However, it is unclear whether lumbar puncture (LP) is routinely required in patients with fever-associated seizures. This study aimed to examine the prevalence of meningitis and encephalitis in adult patients with fever-associated seizures and to evaluate whether LP is routinely required.
We retrospectively studied patients aged ≥16 years who presented to the emergency department with complaints of seizures and fever above 37.5 °C who were admitted to the hospital between January 2017 and December 2019. LP was performed when the emergency physician suspected meningitis or encephalitis. Neurologists assessed patients with normal cerebrospinal fluid (CSF) findings and those admitted without LP after hospitalization. A neurologist confirmed the diagnoses of meningitis and encephalitis.
The study included 148 patients. Ninety-seven patients (65.5%) were male, and the median age was 60 years. LP was performed in 105 patients (70.9%), and 14 (13.4%) had CSF pleocytosis. Meningitis and encephalitis were diagnosed in nine patients (6.1%), of whom four (2.8%) had CNS infections. Patients diagnosed with meningitis and encephalitis were more likely to have Glasgow Coma Scale <13 (P = 0.03) and less likely to have a history of seizures or epilepsy (P = 0.04) and had higher C-reactive protein levels than the other patients (P = 0.02).
The prevalence of meningitis or encephalitis is relatively low in adult patients with fever-associated seizures. Lumbar puncture is considered unnecessary to be performed routinely, but its indication should be carefully considered with reference to the clinical course, comorbidities, and blood tests. Further validation studies with larger sample sizes are needed to confirm the findings of this study.
•Central nervous system infections are emergency diseases causing seizures associated with fever.•The indications for LP in adult patients with seizures remain unclear.•The likelihood of meningitis and encephalitis is relatively low in adult patients with fever-associated seizures.•Lumbar puncture is not routinely necessary for adult patients with fever-associated seizures.
Journal Article
Quantification of Myocardial Iron Deficiency in Nonischemic Heart Failure by Cardiac T2 Magnetic Resonance Imaging
by
Abe, Kohtaro
,
Nagao, Michinobu
,
Mukai, Yasushi
in
Anemia, Iron-Deficiency - diagnosis
,
Anemia, Iron-Deficiency - etiology
,
Anemia, Iron-Deficiency - metabolism
2014
The aim of this study was to use T2* cardiac magnetic resonance (CMR) imaging to quantify myocardial iron content in patients with heart failure (HF) and to investigate the relation between iron content, cardiac function, and the cause of HF. CMR data were analyzed from 167 patients with nonischemic and 31 with ischemic HF and 50 patients with normal ventricular function. Short-axis T2* imaging was accomplished using 3-T scanner and multiecho gradient-echo sequence. Myocardial T2* value (M-T2*) was calculated by fitting the signal intensity data for the mid–left ventricular (LV) septum to a decay curve. Patients with nonischemic HF were categorized into patients with LV ejection fraction (LVEF) <35% or ≥35%. The relation between nonischemic HF with LVEF <35% and the risk for major adverse cardiac events was analyzed by multivariate logistic regression analysis using M-T2* and HF biomarkers. M-T2* was significantly greater for patients with nonischemic HF (LVEF <35%: 29 ± 7 ms, LVEF ≥35%: 26 ± 5 ms) than for patients with normal LV function (22 ± 3 ms, p <0.0001) or ischemic HF (22 ± 4 ms, p <0.001). The odds ratio was 1.21 for M-T2* (p <0.0001) and 1.0015 for brain natriuretic peptide (p <0.0001) in relation to nonischemic HF with LVEF <35%. Furthermore, this value was 0.96 for systolic blood pressure (p = 0.012) and 1.02 for M-T2* (p = 0.03) in relation to the risk for major adverse cardiac events in patients with nonischemic HF. In conclusion, T2* CMR demonstrated the robust relation between myocardial iron deficiency and nonischemic HF. M-T2* is a biomarker that can predict adverse cardiac function in patients with nonischemic HF.
Journal Article
Kinetic approach to superconductivity hidden behind a competing order
2018
Exploration for superconductivity is one of the research frontiers in condensed matter physics. In strongly correlated electron systems, the emergence of superconductivity is often inhibited by the formation of a thermodynamically more stable magnetic/charge order. Thus, to develop the superconductivity as the thermodynamically most stable state, the free-energy balance between the superconductivity and the competing order has been controlled mainly by changing thermodynamic parameters, such as the physical/chemical pressure and carrier density. However, such a thermodynamic approach may not be the only way to materialize the superconductivity. Here, we present a new kinetic approach to avoiding the competing order and thereby inducing persistent superconductivity. In the transition-metal dichalcogenide IrTe2 as an example, by utilizing current-pulse-based rapid cooling up to 10^7 K/s, we successfully kinetically avoid a first-order phase transition to a competing charge order and uncover metastable superconductivity hidden behind. Because the electronic states at low temperatures depend on the history of thermal quenching, electric pulse applications enable non-volatile and reversible switching of the metastable superconductivity, a unique advantage of the kinetic approach. Thus, our findings provide a new approach to developing and manipulating superconductivity beyond the framework of thermodynamics.
Real-space observation of emergent complexity of phase evolution in micrometer-sized IrTe\\(_2\\) crystals
2021
We report complex behaviors in the phase evolution of transition-metal dichalcogenide IrTe\\(_2\\) thin flakes, captured with real-space observations using scanning Raman microscopy. The phase transition progresses via growth of a small number of domains, which is unlikely in statistical models that assume a macroscopic number of nucleation events. Consequently, the degree of phase evolution in the thin flakes is quite variable for the selected specimen and for a repeated measurement sequence, representing the emergence of complexity in the phase evolution. In the \\(\\sim\\)20-\\(\\mu\\)m\\(^3\\)-volume specimen, the complex phase evolution results in the emergent coexistence of a superconducting phase that originally requires chemical doping to become thermodynamically stable. These findings indicate that the complexity involved in phase evolution considerably affects the physical properties of a small-sized specimen.
Nanoscale imaging of unusual photo-acoustic waves in thin flake VTe\\(_2\\)
by
Shimojima, T
,
Ishizaka, K
,
Sakai, H
in
Acoustic propagation
,
Acoustic properties
,
Acoustic waves
2020
Controlling acoustic phonons, the carriers of sound and heat, has been attracting great attention toward the manipulation of sonic and thermal properties in nanometric devices. In particular, the photo-acoustic effect using ultrafast optical pulses has a promising potential to optically manipulate phonons in picoseconds time regime. However, its mechanism has been so far mostly based on the commonplace thermoelastic expansion in isotropic media, limiting the spectrum of potential applications. We investigate a conceptually new mechanism of photo-acoustic effect involving the structural instability, by utilizing a transition-metal dichalcogenide VTe\\(_2\\) with the ribbon-type charge-density-wave (CDW). Ultrafast electron microscope imaging and diffraction measurements reveal the generation and propagation of unusual acoustic waves in the nanometric thin plate associated with the optically induced instantaneous charge-density-wave dissolution. Our results highlight the capability of photo-induced structural instability as a source of coherent acoustic waves.