Anomalous Hall Transport by Optically Injected Isospin Degree of Freedom in Dirac Semimetal Thin Film.

Chirality of massless fermions emerging in condensed matter is a key to understand their characteristic behavior as well as to exploit their functionality. However, the chiral nature of massless fermions in Dirac semimetals has remained elusive, due to equivalent occupation of carriers with the opposite chirality in thermal equilibrium. Here, we show that the isospin degree of freedom, which labels the chirality of massless carriers from a crystallographic point of view, can be injected by circularly polarized light. Terahertz Faraday rotation spectroscopy successfully detects the anomalous Hall conductivity by a light-induced isospin polarization in a three-dimensional Dirac semimetal, Cd3As2. Spectral analysis of the Hall conductivity reveals a long scattering time and a long decay time, which are characteristic of the isospin. The long-lived, robust, and reversible character of the isospin promises a potential application of Dirac semimetals in future information technology.

Sub-10-fs pulse generation from 10 nJ Yb-fiber laser with cascaded nonlinear pulse compression.

We demonstrate cascaded nonlinear pulse compression of a Yb-doped fiber laser. The system is based on two pulse compression stages with bare single-mode fiber (SMF) and ultra-high NA (UHNA) fibers combined with two pairs of chirped mirrors. The 10 nJ, 110 fs input pulses are compressed down to 9.1 fs at 90 MHz, revealing a broadband spectrum from 800 nm to 1350 nm. This technique provides a simple approach to sub-10-fs compact Yb-doped fiber lasers for a variety of applications.

Initial hemodynamic status and Acute Mortality in Cancer patients with Acute Pulmonary Embolism: from the COMMAND VTE Registry.

BACKGROUND: Initial hemodynamic status in patients with acute pulmonary embolism (PE) concerns their acute clinical outcomes. Nevertheless, the characteristics of initial hemodynamic dysfunction and acute mortality in PE patients with active cancer is still controversial. METHODS: We analyzed the data of 1715 PE patients in the COMMAND VTE Registry to compare initial hemodynamic dysfunction, management strategies, and mortality outcomes at 30 days after PE diagnosis between patients with and without active cancer (N = 393 and N = 1322). RESULTS: The patients with active cancer showed lower prevalence of right ventricular dysfunction (35.4% vs. 49.5%, P < 0.001), shock (6.4% vs. 11.6%, P = 0.003), and cardiac arrest (1.8% vs. 5.5%, P = 0.002) at PE diagnosis, compared with those without. The patients with active cancer less frequently received systemic thrombolysis (4.1% vs. 12.6%, P < 0.001) than those without. There was no significant difference in the cumulative 30-day incidence of PE-related death between patients with and without active cancer (4.1% vs. 4.2%, P = 0.89). The cumulative 30-day incidence of all-cause death was significantly higher in patients with active cancer than in those without (11.5% vs. 4.9%, P < 0.001). CONCLUSIONS: PE patients with active cancer less frequently present with initial hemodynamic dysfunction at PE diagnosis, compared with those without. Nevertheless, PE patients with active cancer still show a similar risk of PE-related death and a higher risk of all-cause death at 30 days after PE diagnosis, suggesting the importance of prudent management for this patient population even if their initial hemodynamic status are not compromised.

Statins use and recurrent venous thromboembolism in the direct oral anticoagulant era: insight from the COMMAND VTE Registry-2.

Statins were reported to have a potential effect of primary prevention of venous thromboembolism (VTE), although that of secondary prevention remains uncertain. To investigate the association between statins use and recurrent VTE in the current era. The COMMAND VTE Registry-2 is a multicenter registry enrolling 5,197 consecutive VTE patients among 31 centers in Japan between January 2015 and August 2020. We divided the entire cohort into 2 groups according to statins use at the time of discharge; the statins (N = 865) and no statins groups (N = 4332). The statins group was older (72.9 vs. 66.7 years, P < 0.001), and less often had active cancer (22.0% vs. 30.4%, P < 0.001). The cumulative incidence of discontinuation of anticoagulation was significantly lower in the statins group (60.3% vs. 52.6%, Log-rank P < 0.001). The cumulative 5-year incidence of recurrent VTE was significantly lower in the statins group (6.8% vs. 10.1%, Log-rank P = 0.01). Even after adjusting for the confounders, the lower risk of the statins group relative to the no statins group remained significant for recurrent VTE (HR 0.65, 95% CI 0.45-0.91, P = 0.01). The cumulative 5-year incidence of major bleeding was significantly lower in the statins group (12.2% vs. 14.1%, Log-rank P = 0.04), although, after adjusting for the confounders, the risk of the statins group relative to the no statins group turned to be insignificant (HR 0.77, 95% CI 0.59-1.00, P = 0.054). In this large real-world VTE registry, statins use was significantly associated with a lower risk for the recurrent VTE in the current era.

Factors influencing the prognosis of patients with acute cerebral infarction who received usual care: a multicenter prospective cohort study.

[Purpose] The prognostic factors for patients with acute stroke who received usual care (mobilization ≥48 h after admission) remain unclear. This study aimed to investigate the prognostic factors that predict functional outcomes using evaluations performed immediately after onset in patients with acute cerebral infarction who received usual care from admission until discharge. [Participants and Methods] Participants with acute cerebral infarction admitted to five acute care hospitals in Tokyo and Saitama, Japan and prescribed physical therapy were included. Participants information, functional evaluations, and progress were recorded during the first physical therapy session, mobilization, and discharge. Participants who received usual care were assigned to either the good- or poor-outcome group based on the Modified Rankin Scale at discharge. [Results] In total, 161 Participants receiving usual care (mobilization ≥48 h after admission) were included. Reinfarction and the First National Institutes of Health Stroke Scale score were identified as independent predictors of functional outcome at hospital discharge in participants who received usual care (median, 22.0 d). The cutoff NIHSS score was 4. [Conclusion] Our results provided evidence that the National Institutes of Health Stroke Scale score and reinfarction are useful predictors of functional outcomes in participants who received usual care.

Probing thermal dissipation dimensionality to laser ablation in the pulse duration range from 300 fs to 1 µs.

We propose a quantitative method to determine the thermal dissipation dimensionality to laser ablation. We derived an analytical expression for the melting condition due to a single pulse for arbitrary spot diameters and pulse durations, which explicitly contains the dimensionality of the thermal diffusion process. As a demonstration, we compared the analytical expression with multi-shot ablation thresholds measured over pulse durations of more than six orders of magnitude for copper. The result shows that the thermal dissipation processes dominate for pulse durations longer than 5 ps, while nonthermal processes begin to dominate for shorter pulse durations.

Jitter correction for asynchronous optical sampling terahertz spectroscopy using free-running pulsed lasers.

We demonstrate a jitter correction method for asynchronous optical sampling (ASOPS) terahertz (THz) time-domain spectroscopy using two free-running oscillators. This method simultaneously records the THz waveform and a harmonic of the laser repetition rate difference, Δ f r, to monitor the jitter information for software jitter correction. By suppressing the residual jitter below 0.1 ps, the accumulation of the THz waveform is achieved without losing the measurement bandwidth. Our measurement of water vapor successfully resolves the absorption linewidths below 1 GHz, demonstrating a robust ASOPS with a flexible, simple, and compact setup without any feedback control or additional continuous-wave THz source.

Disentangling the Competing Mechanisms of Light-Induced Anomalous Hall Conductivity in Three-Dimensional Dirac Semimetal.

We experimentally elucidate the origin of the anomalous Hall conductivity in a three-dimensional Dirac semimetal, Cd_{3}As_{2}, driven by circularly polarized light. Using time-resolved terahertz Faraday rotation spectroscopy, we determine the transient Hall conductivity spectrum with special attention to its sign. Our results clearly show the dominance of direct photocurrent generation assisted by the terahertz electric field. The contribution from the Floquet-Weyl nodes is found to be minor when the driving light is in resonance with interband transitions. We develop a generally applicable classification of microscopic mechanisms of light-induced anomalous Hall conductivity.

Predictive factors for walking in acute stroke patients: a multicenter study using classification and regression tree analysis.

[Purpose] Walking ability should be predicted as early as possible in acute stroke patients. The purpose is to construct a prediction model for independent walking from bedside assessments using classification and regression tree analysis. [Participants and Methods] We conducted a multicenter case-control study with 240 stroke patients. Survey items included age, gender, injured hemisphere, the National Institute of Health Stroke Scale, the Brunnstrom Recovery Stage for lower extremities, and "turn over from a supine position" from the Ability for Basic Movement Scale. The National Institute of Health Stroke Scale items, such as language, extinction, and inattention, were grouped under higher brain dysfunction. We used the Functional Ambulation Categories to classify patients into independent (four or more the Functional Ambulation Categories; n=120) and dependent (three or fewer the Functional Ambulation Categories; n=120) walking groups. A classification and regression tree analysis was used to create a model to predict independent walking. [Results] The Brunnstrom Recovery Stage for lower extremities, "turn over from a supine position" from the Ability for Basic Movement Scale, and higher brain dysfunction were the splitting criteria for classifying patients into four categories: Category 1 (0%), severe motor paresis; Category 2 (10.0%), mild motor paresis and could not turn over; Category 3 (52.5%), with mild motor paresis, could turn over, and had higher brain dysfunction; and Category 4 (82.5%), with mild motor paresis, could turn over, and no higher brain dysfunction. [Conclusion] We constructed a useful prediction model for independent walking based on the three criteria.

Autonomous parameter optimization for femtosecond laser micro-drilling.

There is a strong need for a highly efficient method to find the optimal conditions to achieve a desired result in laser processing, oftentimes from a multidimensional parameter space. In this study, we adopted Bayesian optimization as an efficient statistical optimization method robust to the inherent variations observed in typical laser processing results. Specifically, the intensity and spatial beam profile of a femtosecond laser processing system were optimized according to results obtained from an in situ optical microscope observation. In this way, we show that the optimum set of parameters to achieve a desired shape can be obtained autonomously and more than an order of magnitude faster than with a simple grid-search.

200-Hz longitudinal-mode linewidth found in a free-running mode-locked Yb:fiber laser.

We surveyed the longitudinal-mode linewidth of five homemade mode-locked Yb:fiber lasers by taking the beat note with a Hz-level narrow-linewidth CW laser. We systematically varied the resolution bandwidth of the spectrum analyzer and found that the linewidth can be as narrow as 200 Hz, which surpassed the records for free-running mode-locked lasers in the literature to our best knowledge. Based on the survey, we propose that making the cavity long and simple is a good working hypothesis for narrowing the linewidth and provide practical techniques to reduce the environmental fluctuations.

Real-time high-spectral-resolution mid-infrared spectroscopy with a signal-to-noise ratio of ten thousand.

We developed a mid-infrared spectroscopy system with high spectral resolution and a high signal-to-noise ratio using an extremely high-order germanium immersion grating. The spectroscopic system covers wavelengths from 3 to 5 µm and has a spectral resolution of 1 GHz with a single-shot bandwidth of 2 THz. We proposed a method of improving the signal-to-noise ratio and achieved a ratio of over 3000 with a data acquisition rate of 125 Hz in the presence of fluctuations in the light source and environment. A signal-to-noise ratio of 10,000 was achieved with 0.1-s integration for 100-µW mid-infrared light.

Ultrafast time-resolved single-shot birefringence microscopy for laser-induced anisotropy.

The interaction between ultrashort laser pulses and materials in the ultrafast time domain, especially regarding the effect of laser polarization, has attracted much attention. In this study, ultrafast time-resolved single-shot birefringence microscopy is performed to observe laser-induced anisotropy. The birefringences of the optical Kerr effect and laser-induced anisotropic nanostructures by femtosecond laser pulses in silica glass are measured, and their slow axis is confirmed to correspond to the linear polarization angle of the pump light. We discuss the time variations of these birefringences in the picosecond time domain.

Stimulated Rayleigh Scattering Enhanced by a Longitudinal Plasma Mode in a Periodically Driven Dirac Semimetal Cd_{3}As_{2}.

Using broadband (12-45 THz) multi-terahertz spectroscopy, we show that stimulated Rayleigh scattering dominates the transient optical conductivity of cadmium arsenide, a Dirac semimetal, under an optical driving field at 30 THz. The characteristic dispersive line shape with net optical gain is accounted for by optical transitions between light-induced Floquet subbands, strikingly enhanced by the longitudinal plasma mode. Stimulated Rayleigh scattering with an unprecedentedly large refractive index change may pave the way for slow light generation in conductive solids at room temperature.

Risk factors of thrombotic recurrence and major bleeding in patients with intermediate-risk for recurrence of venous thromboembolism.

Prolonged anticoagulation therapy is recommended for patients with intermediate-risk for recurrence of venous thromboembolism (VTE). The current study aimed to identify risk factors of VTE recurrence and major bleeding in intermediate-risk patients. The COMMAND VTE Registry is a multicenter registry enrolled consecutive 3027 patients with acute symptomatic VTE among 29 centers in Japan. The current study population consisted of 1703 patients with intermediate-risk for recurrence. The primary outcome measure was recurrent VTE during the entire follow-up period, and the secondary outcome measures were recurrent VTE and major bleeding during anticoagulation therapy. In the multivariable Cox regression model for recurrent VTE incorporating the status of anticoagulation therapy as a time-updated covariate, off-anticoagulation therapy was strongly associated with an increased risk for recurrent VTE (HR 9.42, 95% CI 5.97-14.86). During anticoagulation therapy, the independent risk factor for recurrent VTE was thrombophilia (HR 3.58, 95% CI 1.56-7.50), while the independent risk factors for major bleeding were age ≥ 75 years (HR 2.04, 95% CI 1.36-3.07), men (HR 1.52, 95% CI 1.02-2.27), history of major bleeding (HR 3.48, 95% CI 1.82-6.14) and thrombocytopenia (HR 3.73, 95% CI 2.04-6.37). Among VTE patients with intermediate-risk for recurrence, discontinuation of anticoagulation therapy was a very strong independent risk factor of recurrence during the entire follow-up period. The independent risk factors of recurrent VTE and those of major bleeding during anticoagulation therapy were different: thrombophilia for recurrent VTE, and advanced age, men, history of major bleeding, and thrombocytopenia for major bleeding. CLINICAL TRIAL REGISTRATION: Unique identifier: UMIN000021132. COMMAND VTE Registry: http://www.umin.ac.jp/ctr/index.htm .

Periprocedural management and clinical outcomes of invasive procedures after venous thromboembolism: from the COMMAND VTE registry.

Anticoagulation therapy is prescribed for the prevention of recurrence in patients with venous thromboembolism, which could be temporarily interrupted during invasive procedures. The COMMAND VTE Registry is a multicenter registry enrolling 3027 consecutive patients with acute symptomatic VTE in Japan between January 2010 and August 2014. We identified patients who underwent invasive procedures during the entire follow-up period and evaluated periprocedural managements and clinical outcomes at 30 days after invasive procedures. During a median follow-up period of 1213 (IQR: 847-1764) days, 518 patients underwent invasive procedures with the cumulative incidences of 5.8% at 3 months, 11.1% at 1 year, and 24.0% at 5 years. Among 382 patients in high bleeding-risk category of invasive procedures, anticoagulation therapy had been discontinued already in 62 patients (16%) and interrupted temporarily in 288 patients (75%) during the invasive procedures with bridging anticoagulation therapy with heparin in 214 patients (56%). Among 80 patients in low bleeding-risk category, anticoagulation therapy had been already discontinued in 15 patients (19%) and interrupted temporarily in 31 patients (39%) during invasive procedure with bridging anticoagulation therapy with heparin in 17 patients (21%). At 30 days after the invasive procedures, 14 patients (2.7%) experienced recurrent VTE, while 28 patients (5.4%) had major bleeding. This study elucidated the real-world features of peri-procedural management and prognosis in patients with VTE who underwent invasive procedures during follow-up in the large multicenter VTE registry. The 30-day incidence rates of recurrent VTE and major bleeding events were 2.7% and 5.4%.

Independent contribution of optical attenuation length in ultrafast laser-induced structural change.

Although laser irradiation with femtosecond pulses is known to generate crystallization and morphological changes, the contribution of optical parameters to material changes is still in discussion. Here, we compare two structures irradiated near Si-L2,3 edges by an extreme ultraviolet femtosecond pulse. Our result implies that, despite the femtosecond irradiation regime, these values of the optical attenuation length between the wavelengths of 10.3-nm and 13.5-nm differ by one order of magnitude. From the structural comparison, the original crystalline state was maintained upon irradiation at 13.5-nm, on the other hand, transition to an amorphous state occurred at 10.3-nm. The difference in optical attenuation length directly influence to the decision of material crystallization or morphological changes, even if the irradiation condition is under the femtosecond regime and same pulse duration. Our result reveals the contribution of optical attenuation length in ultrafast laser-induced structural change.

Direct generation of sub-picosecond pulse via multi-section gain switching.

We have directly generated optical pulses having a duration of 0.56 ps with a peak power of 25 W by gain switching of multi-section semiconductor lasers in which the optimized lengths of the absorption and gain regions were 50 and 200 µm, respectively. Even though the experiment was conducted via impulsive optical pumping at a low temperature, we observed that the multi-section gain switching suppresses the low-energy tail and chirping inherent to conventional gain switching in single-section lasers and is useful in direct short-pulse generation.

Clinical characteristics and outcomes of patients with venous thromboembolism according to diagnosis on weekends versus on weekdays.

There are uncertainties on the influence of the days of diagnosis in a week (weekends versus weekdays) on clinical outcomes in patients with acute venous thromboembolism (VTE), including pulmonary embolism (PE) and deep vein thrombosis (DVT). The COMMAND VTE registry is a multicenter cohort study enrolling 3027 consecutive patients with acute symptomatic VTE. The current study population consisted of 337 patients diagnosed on weekends and 2690 patients diagnosed on weekdays. We compared the clinical characteristics, management strategies and 30-day outcomes between the 2 groups. The patients diagnosed on weekends more often presented with PE (72% vs. 55%, P < 0.001), and with more severe hemodynamic condition for PE patients. The patients diagnosed on weekends more often received initial parenteral anticoagulation therapy and thrombolysis than those diagnosed on weekdays. The cumulative 30-day incidence of all-cause death was not significantly different between the two groups among PE patients (diagnosis on weekends: 6.2% vs. diagnosis on weekdays: 6.5%, P = 0.87), as well as among DVT patients (0.0% vs. 1.5%, P = 0.24). The most frequent cause of deaths was fatal PE in both groups among PE patients. The risks for recurrent VTE and major bleeding at 30-day were not significantly different between the 2 groups among PE patients, nor among DVT only patients. In conclusion, the VTE patients diagnosed on weekends presented more often with PE, and with more severe condition for PE patients. Nevertheless, the risk for 30-day mortality was not significantly different between patients diagnosed on weekends and on weekdays.

Factors Influencing Sitting Ability During the Acute Post-Stroke Phase: A Multicenter Prospective Cohort Study in Japan.

OBJECTIVES: Sitting ability during the acute phase after stroke is a useful indicator of functional outcomes; however, factors that affect this ability have not been evaluated. Therefore, this study aimed to identify and evaluate factors that affect sitting ability in the acute phase after stroke. MATERIALS AND METHODS: This multicenter prospective cohort study included hemispheric stroke patients who underwent an inpatient rehabilitation program after acute stroke from five acute care hospitals. The effect of age, sex, lesion side, etiology, consciousness disorder, stroke and dementia history, stroke-related complications, National Institutes of Health Stroke Scale score, hemiparalysis, turn-over movement from the supine position and sit-up movement, and Scale for Contraversive Pushing on the "remain sitting" item in the revised version of the Ability of Basic Movement Scale at the time of acute hospital discharge were investigated. Factors affecting sitting ability were identified using binomial logistic regression analysis. RESULTS: We included 293 stroke patients. Age (odds ratio: 0.943, 95% confidence interval: 0.910-0.977, p=0.001), National Institutes of Health Stroke Scale score (odds ratio: 0.862, 95% confidence interval: 0.811-0.916, p<0.001), and Scale for Contraversive Pushing score (odds ratio: 0.543, 95% confidence interval: 0.419-0.705, p<0.001) were identified as independent predictors of sitting ability at the time of hospital discharge (median; 23.0 days). CONCLUSIONS: Older patients and those with high Scale for Contraversive Pushing and National Institutes of Health Stroke Scale scores experienced difficulties in regaining sitting ability. These results may guide physical therapy for patients with impaired sitting ability due to hemispheric stroke.