72 research outputs found

    Programmable generation of counterrotating bicircular light pulses in the multi-terahertz frequency range

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    The manipulation of solid states using intense infrared or terahertz light fields is a pivotal area in contemporary ultrafast photonics research. While conventional circular polarization has been well explored, the potential of counterrotating bicircular light remains widely underexplored, despite growing interest in theory. In the mid-infrared or multi-terahertz region, experimental challenges lie in difficulties in stabilizing the relative phase between two-color lights and the lack of available polarization elements. Here, we successfully generated phase-stable counterrotating bicircular light pulses in the 10-40 THz frequency range circumventing the above problems. Employing spectral broadening, polarization pulse shaping with a spatial light modulator, and intra-pulse difference frequency generation leveraging a distinctive angular-momentum selection rule within the nonlinear crystal, we achieved direct conversion from near-infrared pulses into the designed counterrotating bicircular multi-terahertz pulses. Use of the spatial light modulator enables programmable control over the shape, orientation, rotational symmetry, and helicity of the bicircular light field trajectory. This advancement provides a novel pathway for the programmable manipulation of light fields, and marks a significant step toward understanding and harnessing the impact of tailored light fields on matter, particularly in the context of topological semimetals.Comment: 15 pages, 3 figure

    Preoperative Evaluation of Computed Tomography Perfusion: Its Significance for the Risk Assessment of Cerebrovascular Complications Perioperatively1

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    Neurological complications occur with an overall frequency of 2.8% perioperatively. Although ultrasound imaging is an excellent modality for the risk assessment of carotid arterial diseases, no comprehensive information can be obtained with respect to the intracranial cerebral blood flow. Recent advent of computed tomography perfusion (CTP) imaging has made it possible to directly measure the cerebral blood flow at any intracranial region of interest. We describe here an efficacy of CT perfusion imaging in the preoperative settings for the risk assessment of neurological complications, especially in cases with carotid arterial stenosis/occlusion

    A Case of Severe Hemorrhagic Cystitis Caused by Melphalan with Successful Bladder Preservation by Ligation of Bilateral Internal Iliac Arteries

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    Hemorrhagic cystitis is a disorder which causes bleeding from diffusely inflammatory bladder mucosa. Here we present a case of severe hemorrhagic cystitis caused by melphalan. A 70-year-old man with multiple myeloma was presented with suddenly commenced massive gross hematuria. During an attempt of transurethral coagulation of bladder mucosa, bladder perforation into peritoneal cavity was suspected, then open laparotomy was indicated. We isolated bilateral internal iliac arteries and ligated them in order to control continued bleeding. After that, bladder bleeding was suddenly diminished. Ligation of internal iliac arteries may be a choice in controlling massive bleeding from bladder with severe hemorrhagic cystitis when laparotomy was inevitable

    Dynamics of light-induced anomalous Hall effect in the three-dimensional Dirac semimetal Cd3_3As2_2

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    We experimentally study the dynamical behavior of the light-induced anomalous Hall effect in a three-dimensional Dirac semimetal, Cd3_3As2_2. An ultrashort, circularly polarized, multi-terahertz pump pulse breaks the time-reversal symmetry of a thin film sample. The resulting anomalous Hall effect is clearly observed through the polarization rotation of a single-cycle terahertz probe pulse. Comparing the experimental result with theory, we find that the field-induced injection current dominates the anomalous Hall effect during pump irradiation, while the Berry curvature of the Floquet-Weyl semimetal state does not appreciably contribute. Remarkably, even after pump irradiation, we observe an anomalous Hall effect that lasts for more than 10 ps. A model fit to the Hall conductivity spectrum reveals a relatively long scattering time over 400 fs. This result shows that circularly polarized light creates a polarization of the isospin degree of freedom in the Dirac semimetal, which labels the crystallographic point group representation of the overlapping Weyl semimetal bands. Our observation paves the way for conversion of a robust isospin flow into an electric current at room temperature, being a new analogue of the inverse spin Hall effect.Comment: 44 pages, 14 figure

    Radioligand Assay-Based Detection of Antibodies against SARS-CoV-2 in Hospital Workers Treating Patients with Severe COVID-19 in Japan.

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    This study aimed to clarify whether infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is prevalent among the staff of a hospital providing treatment to patients with severe coronavirus disease 2019 (COVID-19) using radioligand assay (RLA). One thousand samples from the staff of a general hospital providing treatment to patients with severe COVID-19 were assayed for SARS-CoV-2 nucleocapsid protein (N) IgG using RLA. Nine patients with COVID-19 who had been treated in inpatient settings and had already recovered were used as control subjects, and 186 blood donor samples obtained more than 10 years ago were used as negative controls. Four of the 1000 samples showed apparently positive results, and approximately 10 or more samples showed slightly high counts. Interestingly, a few among the blood donor samples also showed slightly high values. To validate the results, antibody examinations using ELISA and neutralizing antibody tests were performed on 21 samples, and chemiluminescence immunoassay (CLIA) was performed on 201 samples, both resulting in a very high correlation. One blood donor sample showed slightly positive results in both RLA and CLIA, suggesting a cross-reaction. This study showed that five months after the pandemic began in Japan, the staff of a general hospital with a tertiary emergency medical facility had an extremely low seroprevalence of the antibodies against SARS-CoV-2. Further investigation will be needed to determine whether the slightly high results were due to cross-reactions or a low titer of anti-SARS-CoV-2 antibodies. The quantitative RLA was considered sensitive enough to detect low titers of antibodies

    Signal-Limitation Filters to Simultaneously Satisfy Constraints of Velocity and Acceleration Signals

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    In this paper, we propose a filter structure whose output satisfies the velocity and acceleration constraints for any input signals. In the field of factory automation, step signals are sometimes converted into trapezoidal waves to satisfy the intended velocity limitations. This helps the operators avoid overload in industrial robots. In some cases, physical protection of the equipment, safety, and ride quality can be ensured by limiting the characteristics of input signals in actual plants. A signal-limitation filter is proposed for the input signal to satisfy the intended signal limit. In the previous study, a signal-limitation filter structure was provided as a simple unit-feedback control with a saturation function. The filter structure in the previous study had a delay between the input and output signals because it is difficult to design gains considering both the saturating and non-saturating cases. To solve this problem, we propose a novel filter structure that includes feedforward and feedback components. Applying this filter structure with feedforward terms including saturation enables us to fulfill the desired limitations for arbitrary input signals. We evaluated the proposed structure in a signal-limitation filter that simultaneously limits the velocity and acceleration. The simulation results demonstrate the effectiveness of our proposed filter

    Utility of Regular Management of Physical Activity and Physical Function in Hemodialysis Patients

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    Background/Aims: Several clinical practice guidelines recommend regular assessment of physical activity and physical function as part of routine care in hemodialysis patients. However, there is no clear evidence to support these recommendations. We investigated whether the proportion of attendance at a regular program for management of physical activity and physical function can predict all-cause mortality and cardiovascular events in hemodialysis patients. Methods: This retrospective cohort study consisted of 266 hemodialysis patients participating in the management program at least once. Participants were tracked for 3 years after their first attendance at the management program to determine their attendance proportion. The main study outcomes included all-cause mortality and a composite of fatal and nonfatal cardiovascular events. Results: Median patient age was 64.5 (interquartile range, 56.8 – 72.0) years, 45% were women, and the median time on hemodialysis was 35.5 (interquartile range, 12.0 – 114.3) months at baseline. Sixty-five patients died over a median follow-up of 79 months. The incidence of cardiovascular events was 60 over a median follow-up of 68 months. Even after adjusting for any of the prognostic models, participants who attended ≤ 75% of sessions (n = 140) had higher risks of mortality (hazard ratio (HR), 1.79; 95% confidence interval (CI): 1.00 – 3.36; P = 0.049) and cardiovascular events (HR, 1.84; 95% CI: 1.07 – 3.48; P = 0.03) than those attending > 75% of sessions (n = 126). Conclusion: Hemodialysis patients in whom physical activity and physical function could be assessed more regularly had better prognosis than those with only intermittent assessment

    Association of Cardiovascular Health Metrics With Risk of Transition to Hypertension in Non-Hypertensive Young Adults

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    BACKGROUND The risk of developing hypertension in young adults and its relationship to modifiable lifestyle factors are unclear. We aimed to examine the association of cardiovascular health (CVH) metrics with the risk of hypertension. METHODS We analyzed 66,876 participants aged 20-39 years, with available blood pressure (BP) data for 5 consecutive years, who had normal or elevated BP at the initial health check-up, enrolled in the JMDC Claims Database. Ideal CVH metrics included nonsmoking, body mass inde
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