Quantum geometry, optical absorption and topological gap bound

We present a generalized sum rule for optical absorption and magnetic circular dichroism in insulators, and derive a general tight bound on the energy gap of topological insulators. The two findings are shown to be intimately related through quantum geometry. Our theory is applied to infrared absorption near topological band inversion, and to topological gap in moir\'e materials.Comment: 9 pages, 1 figur

Probing quantum geometry through optical conductivity and magnetic circular dichroism

Probing ground-state quantum geometry and topology through optical response is not only of fundamental interest, but it can also offer several practical advantages. Here, using first-principles calculations on antiferromagnetic topological insulator MnBi$_2$Te$_4$ thin films, we demonstrate how the generalized optical weight arising from the absorptive part of the optical conductivity can be used to probe the ground state quantum geometry and topology. We show that three septuple layers MnBi$_2$Te$_4$ exhibit an enhanced almost perfect magnetic circular dichroism for a narrow photon energy window in the infrared region. We calculate the quantum weight in a few septuple layers MnBi$_2$Te$_4$ and show that it far exceeds the lower bound provided by the Chern number. Our results suggest that the well-known optical methods are powerful tools for probing the ground state quantum geometry and topology

Quantum metric nonlinear Hall effect in a topological antiferromagnetic heterostructure

Quantum geometry - the geometry of electron Bloch wavefunctions - is central to modern condensed matter physics. Due to the quantum nature, quantum geometry has two parts, the real part quantum metric and the imaginary part Berry curvature. The studies of Berry curvature have led to countless breakthroughs, ranging from the quantum Hall effect in 2DEGs to the anomalous Hall effect (AHE) in ferromagnets. However, in contrast to Berry curvature, the quantum metric has rarely been explored. Here, we report a new nonlinear Hall effect induced by quantum metric by interfacing even-layered MnBi2Te4 (a PT-symmetric antiferromagnet (AFM)) with black phosphorus. This novel nonlinear Hall effect switches direction upon reversing the AFM spins and exhibits distinct scaling that suggests a non-dissipative nature. Like the AHE brought Berry curvature under the spotlight, our results open the door to discovering quantum metric responses. Moreover, we demonstrate that the AFM can harvest wireless electromagnetic energy via the new nonlinear Hall effect, therefore enabling intriguing applications that bridges nonlinear electronics with AFM spintronics.Comment: 19 pages, 4 figures and a Supplementary Materials with 66 pages, 4 figures and 3 tables. Originally submitted to Science on Oct. 5, 202

Validation of the Burden Index of Caregivers (BIC), a multidimensional short care burden scale from Japan

BACKGROUND: We constructed a concise multidimensional care burden scale that reflects circumstances unique to Japan, with a focus on intractable neurological diseases. We surveyed 646 family caregivers of patients with intractable neurological diseases or stroke using 28 preliminary care burden scale items obtained from qualitative research. The results were used to finalize the feeling of care burden scale (BIC: burden index of caregivers), and verify its reliability and validity. METHODS: The survey was conducted among caregivers providing home health care to patients with intractable neurological diseases (PD [Parkinson's disease], SCD [spinocerebellar degeneration], MSA [multiple system atrophy], and ALS [amyotrophic lateral sclerosis]) or CVA (cerebrovascular accident) using a mailed, self-administered questionnaire between November, 2003 and May, 2004. RESULTS: Response rates for neurological and CVA caregivers were 50% and 67%, respectively, or 646 in total (PD, 279; SCD, 78; MSA, 39; ALS, 30; and CVA, 220). Item and exploratory factor analyses led to a reduction to 11 items, comprising 10 items from the 5 domains of time-dependent burden, emotional burden, existential burden, physical burden, and service-related burden; and 1 item on total burden. Examination of validity showed a moderate correlation between each domain of the BIC and the SF-8 (Health related quality of life scale, Short Form-8), while the correlation coefficient of the overall BIC and CES-D was 0.62. Correlation between the BIC and ZBI, a preexisting care burden scale, was high (r = 0.84), while that with the time spent on providing care was 0.47. The ICC (Intraclass correlation coefficient) by test-retest reliability was 0.83, and 0.68 to 0.80 by individual domain. CONCLUSION: These results show that the BIC, a new care burden scale comprising 11 items, is highly reliable and valid

Atrasentan and renal events in patients with type 2 diabetes and chronic kidney disease (SONAR): a double-blind, randomised, placebo-controlled trial

Background: Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes. Methods: We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18–85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR)25–75 mL/min per 1·73 m 2 of body surface area, and a urine albumin-to-creatinine ratio (UACR)of 300–5000 mg/g who had received maximum labelled or tolerated renin–angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0·75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders)were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0·75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for ≥30 days)or end-stage kidney disease (eGFR <15 mL/min per 1·73 m 2 sustained for ≥90 days, chronic dialysis for ≥90 days, kidney transplantation, or death from kidney failure)in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials.gov, number NCT01858532. Findings: Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325)or placebo group (n=1323). Median follow-up was 2·2 years (IQR 1·4–2·9). 79 (6·0%)of 1325 patients in the atrasentan group and 105 (7·9%)of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR]0·65 [95% CI 0·49–0·88]; p=0·0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3·5%)of 1325 patients in the atrasentan group and 34 (2·6%)of 1323 patients in the placebo group (HR 1·33 [95% CI 0·85–2·07]; p=0·208). 58 (4·4%)patients in the atrasentan group and 52 (3·9%)in the placebo group died (HR 1·09 [95% CI 0·75–1·59]; p=0·65). Interpretation: Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease. Funding: AbbVie

High-efficiency energy harvesting based on nonlinear Hall rectifier

Noncentrosymmetric quantum materials can convert AC input current into DC transverse current through the nonlinear Hall effect at zero magnetic field. We analyze the AC-DC power conversion efficiency of such ``Hall rectifier'' and suggest its application in wireless charging and energy harvesting. Our key observation is that the development of Hall voltage results in a change of longitudinal resistance, resulting in a violation of Ohm's law due to the nonlinear Hall effect. This feedback mechanism balances the input power and the output power and hence is crucial to understanding the power transfer from source to load. We derive a general expression for the power conversion efficiency in terms of material parameters, external load resistance, and input power. As the Hall current is perpendicular to the electric field and does not generate Joule heating by itself, we obtain high power conversion efficiency when the Hall angle (which increases with the input power) is large and the load resistance is optimized. Promising materials for high-efficiency Hall rectifiers are also discussed.Comment: 7 pages, 3 figure

Photovoltaic effect in noncentrosymmetric material without optical absorption

We theoretically propose that the direct current is produced by the light without any optical absorption in metals that break both inversion $\mathcal{P}$ and $\mathcal{T}$ symmetries. This process can be regarded as the Raman process leaving the current in the material. Candidate materials for the present photovoltaic effect include multiferroics breaking both $\mathcal{P}$ and $\mathcal{T}$ symmetries. Furthermore, $\mathcal{T}$ symmetric ferroelectrics with slight doping also support similar photocurrent under illumination of circularly polarized light, i.e., the circular photogalvanic effect (CPGE).Comment: 6 pages, 4 figures. Since we found a mistake in the numerical calculation of MoS2 in the 1st version, we deleted them in the 2nd version. We are sorry for your inconvenienc

極域黒色炭素の起源と沈着除去過程の評価

http://www.godac.jamstec.go.jp/darwin/cruise/mirai/mr16-06/ehttp://www.godac.jamstec.go.jp/darwin/cruise/mirai/mr17-05c/