Nematic response revealed by coherent phonon oscillations in BaFe2_2As2_2

We investigate coherent phonon oscillations of BaFe$_2$As$_2$ using optical pump-probe spectroscopy. Time-resolved optical reflectivity shows periodic modulations due to $A_{1g}$ coherent phonon of $c$-axis arsenic vibrations. Optical probe beams polarized along the orthorhombic $a$- and $b$-axes reveal that the initial phase of coherent oscillations shows a systematic deviation as a function of temperature, although these oscillations arise from the same $c$-axis arsenic vibrations. The oscillation-phase remains anisotropic even in the tetragonal structure, reflecting a nematic response of BaFe$_2$As$_2$. Our study suggests that investigation on the phase of coherent phonon oscillations in optical reflectivity can offer unique evidence of a nematic order strongly coupled to a lattice instability.Comment: 5 pages, 4 figure

Abnormal phase flip in the coherent phonon oscillations of Ca2RuO4

We employ an optical pump-probe technique to study coherent phonon oscillations in Ca2RuO4. We find that oscillation amplitude of an Ag symmetric phonon mode is strongly suppressed at 260 K, a putative transition point of orbital ordering. The oscillation also shows a gradual but huge change in its phase, such that the oscillation even flips over with a 180 change across the temperature. Density functional theory calculations indicate that the Ag phonon has an eigenmode of octahedral distortion with conventional tilting along the a axis and antipolar distortion of apical oxygen. Careful inspection of the lattice captures an unusually large antipolar distortion in low-temperature structures, which may play a crucial role for the phase transition at 260 K. ©2018 American Physical Societ

Safety and Clinical Outcomes of Insulin Degludec in Korean Patients with Diabetes in Real-World Practices: A Prospective, Observational Study

Abstrac Introduction To investigate the safety and effectiveness of insulin degludec (IDeg) in a real-world population of Korean patients with diabetes requiring insulin therapy. Methods This was a multicenter, prospective, single-arm, open-label, non-interventional study. Patients aged ≥ 12months and treated with previous glucose-lowering medications were eligible to switch to IDeg. The primary endpoint was the incidence of adverse events (AEs), and the secondary endpoints were changes in glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), postprandial glucose (PPG), and target HbA1c < 7.0%. Results In total, 3225 and 2450 patients were included in the safety analysis set (SAS) and effectiveness analysis set (EAS), respectively. The mean baseline HbA1c and duration of diabetes were 9.4% and 13.0years, respectively. Adverse events were reported in 740 patients (22.9%); the majority were mild and resolved. Significant improvements were observed in HbA1c, FPG, and PPG at week 26 (all p < 0.0001). The target of HbA1c < 7% was achieved in 22.2% of patients at week 26. Conclusion In real-world clinical practice, 26weeks of IDeg treatment resulted in significant reductions in glycemic parameters with a low incidence of AEs in Korean patients with diabetes. No new safety signals were observed. Clinical Trials Registry and Registration Number This trial is registered under ClinicalTrials.gov (NCT02779413) and the universal trial number is [U1111-1176-2287].Sponsorship of this study: medical writing was funded by Novo Nordisk. The sponsor also funded the journals Rapid Service Fee

Nematic Fluctuations in Optimally Doped BaFe1.87Co0.13As2 Observed in Photoinduced Reflectivity Change

The photoinduced reflectivity change of optimally doped BaFe1.87Co0.13As2 is investigated. It is observed that the nematic signal in the photoinduced reflectivity change continues to increase as temperature decreases, reflecting its fluctuating nature. However, fluence-dependent measurements show saturation of the nematic signal at higher pump fluence, a typical behavior of a static order parameter. Temperature-dependent evolution of the saturation and the characteristic relaxation time of the nematic signal suggest that the nematicity of a spin and/or orbital origin develops at lower temperature on top of the nematicity coupled to the lattice that dominates the higher temperature nematic response. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Keldysh space control of charge dynamics in a strongly driven Mott insulator

The fate of a Mott insulator under strong low frequency optical driving conditions is a fundamental problem in quantum many-body dynamics. Using ultrafast broadband optical spectroscopy, we measured the transient electronic structure and charge dynamics of an off-resonantly pumped Mott insulator Ca$_2$RuO$_4$. We observe coherent bandwidth renormalization and nonlinear doublon-holon pair production occurring in rapid succession within a sub-100 femtosecond pump pulse duration. By sweeping the electric field amplitude, we demonstrate continuous bandwidth tuning and a Keldysh cross-over from a multi-photon absorption to quantum tunneling dominated pair production regime. Our results provide a procedure to control coherent and nonlinear heating processes in Mott insulators, facilitating the discovery of novel out-of-equilibrium phenomena in strongly correlated systems.Comment: 6 pages main text, 4 figures, 16 pages supplementary informatio

Evidence of structural evolution in Sr2RhO4 studied by time-resolved optical reflectivity spectroscopy

We investigate ultrafast dynamics from photoinduced reflectivity of Sr2RhO4 by using femtosecond near-infrared pulses. We observe a clear temperature dependent anomaly in its electronic dynamics which slows down below T-S similar to 160 K. In addition, coherent oscillations of the 5.3 THz A(1g) phonon exhibit a 90 degrees. shift in its initial phase across TS, indicating a structural change in octahedral rotation distortions. We propose that octahedral structure in Sr2RhO4 evolves around T-S, and it can influence the nonequilibrium dynamics of photo-induced carriers as well as realtime phonon responses. ©2019 American Physical Society11sciescopu

A Prospective Randomized, Double-Blind, Multi-Center, Phase III Clinical Trial Evaluating the Efficacy and Safety of Olmesartan/Amlodipine plus Rosuvastatin Combination Treatment in Patients with Concomitant Hypertension and Dyslipidemia: A LEISURE Study

Background: This study was a multicenter, randomized, double-blinded, placebo-controlled phase III clinical trial to investigate the efficacy and safety of an olmesartan/amlodipine single pill plus rosuvastatin combination treatment for patients with concomitant hypertension and dyslipidemia. Methods: Patients with both hypertension and dyslipidemia aged 20&ndash;80 were enrolled from 36 tertiary hospitals in Korea from January 2017 to April 2018. Patients were randomized to three groups in a 1:1:0.5 ratio, olmesartan/amlodipine single pill plus rosuvastatin (olme/amlo/rosu) or olmesartan plus rosuvastatin (olme/rosu) or olmesartan/amlodipine single pill (olme/amlo) combination. The primary endpoints were change of sitting systolic blood pressure (sitSBP) from baseline in the olme/amlo/rosu vs. olme/rosu groups and the percentage change of low-density lipoprotein cholesterol (LDL-C) from baseline in the olme/amlo/rosu vs. olme/amlo groups after 8 weeks of treatment. Results: A total of 265 patients were randomized, 106 to olme/amlo/rosu, 106 to olme/rosu and 53 to olme/amlo groups. Baseline characteristics among the three groups did not differ. The mean sitSBP change was significantly larger in the olme/amlo/rosu group with &minus;24.30 &plusmn; 12.62 mmHg (from 153.58 &plusmn; 10.90 to 129.28 &plusmn; 13.58) as compared to the olme/rosu group, &minus;9.72 &plusmn; 16.27 mmHg (from 153.71 &plusmn; 11.10 to 144.00 &plusmn; 18.44 mmHg). The difference in change of sitSBP between the two groups was &minus;14.62&plusmn; 1.98 mmHg with significance (95% CI &minus;18.51 to &minus;10.73, p &lt; 0.0001). The mean LDL-C reduced significantly in the olme/amlo/rosu group, &minus;52.31 &plusmn; 16.63% (from 154.52 &plusmn; 30.84 to 72.72 &plusmn; 26.08 mg/dL) as compared to the olme/amlo group with no change, &minus;2.98 &plusmn; 16.16% (from 160.42 &plusmn; 32.05 to 153.81 &plusmn; 31.57 mg/dL). Significant difference in change was found in LDL-C between the two groups with &minus;50.10 &plusmn; 2.73% (95% CI &minus;55.49 to &minus;44.71, p &lt; 0.0001). Total adverse drug reaction rates were 10.48%, 5.66% and 3.7% in the olme/amlo/rosu, olme/rosu and olme/amlo groups, respectively with no statistical significance among the three groups. Serious adverse drug reactions did not occur. Conclusions: Olmesartan/amlodipine single pill plus rosuvastatin combination treatment for patients with both hypertension and dyslipidemia is effective and safe as compared to either olmesartan plus rosuvastatin or olmesartan plus amlodipine treatment

Ultrafast probes of photovoltage and two-dimensional electron gas in the topological insulator Bi2Te3 by angle-resolved photoemission and terahertz spectroscopy

© 2022 American Physical Society.Photoexcited carriers in three-dimensional topological insulators (3D TIs) decay rapidly through the electron-electron and electron-phonon scattering. While most studies focus on such fast dynamics, recent experiments find the slow photovoltage (PV) dynamics arising from the band-bending potentials, in which the optical transitions in two-dimensional electron gas (2DEG) are effective. Although early investigations speculated the existence of multiple band-bending structures from the TI surface to the TI bulk, how PV and 2DEG are correlated in the presence of such multiple band bendings has been less explored. Here, we employ the combination of time- and angle-resolved photoemission spectroscopy (tr-ARPES) and ultrafast time-resolved terahertz (tr-THz) spectroscopy to investigate the PV and 2DEG dynamics in the prototypical topological insulator Bi2Te3. Our tr-ARPES analysis identifies two spatially separated PV dynamics associated with two types of band bending: one is the well-known surface PV, and another PV is formed deep within the bulk, which we call "internal bulk PV."For the surface PV, our tr-THz spectra substantiate that the μs-long transient signal arises from the surface-PV-induced increase of the TSS and 2DEG carrier density, which appears as a transient blueshift of a Fermi cutoff and an increased ARPES intensity in the tr-ARPES measurements. In contrast, the effect of the internal bulk PV shows only marginal changes in the 2DEG and TSS carrier densities but shifts the entire binding energy of the near-surface bands.11Nsciescopu