High-performance Ge/Si electro-absorption optical modulator up to 85°C and its highly efficient photodetector operation

We studied a high-speed Ge/Si electro-absorption optical modulator (EAM) evanescently coupled with a Si waveguide of a lateral p–n junction for a high-bandwidth optical interconnect over a wide range of temperatures from 25 °C to 85 °C. We demonstrated 56 Gbps high-speed operation at temperatures up to 85 °C. From the photoluminescence spectra, we confirmed that the bandgap energy dependence on temperature is relatively small, which is consistent with the shift in the operation wavelengths with increasing temperature for a Ge/Si EAM. We also demonstrated that the same device operates as a high-speed and high-efficiency Ge photodetector with the Franz-Keldysh (F-K) and avalanche-multiplication effects. These results demonstrate that the Ge/Si stacked structure is promising for both high-performance optical modulators and photodetectors integrated on Si platforms

Direct Bandgap Control by Narrowing the Germanium Strip Structure on Silicon for C+L Band Photonic Devices

This study reports the bandgap engineering of a Ge epitaxial layer on Si to tune the operating wavelength of optical intensity modulators and photodetectors in the C (1.530–1.565μm)+L (1.565–1.625 μm) band. A strip structure of elemental Ge is investigated, rather than wider-gap SiGe or narrower-gap GeSn alloy, to achieve the key property of a C band modulation and improved L band detection. By narrowing the strip to the submicron scale, a tensile lattice strain in Ge, induced by a thermal expansion mismatch with Si, is elastically relaxed by an edge-induced relaxation effect. The photoluminescence peak and photodetection spectra show a significant blue shift as the narrowed direct gap of ~0.77 eV is restored to 0.80 eV of unstrained Ge. A standard SiNx external stressor on a narrow Ge strip induces an increased blue shift or an opposite red shift, depending on the stress polarity in SiNx. The results show that it is possible to tune the operating wavelength of modulators and photodetectors of elemental Ge in the C+L band

Recovery of flow-mediated vasodilatation after repetitive measurements is involved in early vascular impairment: comparison with indices of vascular tone.

In repetitive measurements of flow-mediated dilatation (FMD), the duration of the interval between measurements remains controversial. In this pilot study, we conducted three sequential measurements of low-flow-mediated constriction (L-FMC), FMD and flow-mediated total dilation (FMTD; L-FMC+ FMD) at baseline and intervals of 15 and 60 min in 30 healthy males. FMD15, L-FMC15, and FMTD15 were significantly lower than the respective first measurements, but all indices showed full recovery at 60 min in all subjects. The baseline diameter was slightly increased at 15 min and restored at 60 min, but the maximum diameter, and the baseline and reactive flow velocity unchanged. We examined the relationship between recovery rate of FMTD at 15 min (FMTD-R) and cardio-ankle vascular index (CAVI). Univariate analysis showed moderate correlation between FMTD-R, and CAVI and L-FMC0. Patients were divided according to FMTD-R value; the low-FMTD-R group [below the median value (-26.2%)] included a significantly higher proportion of smokers and higher CAVI values than the high-FMTD-R group. The reproducibility of FMTD and FMTD-R was evaluated in another group of 25 healthy subjects. The range of variation across measurements was 1.1% for FMTD and 4.6% for FMTD-R; with intraclass correlation coefficients of 0.93 and 0.95, respectively. The present study demonstrated blunted recovery of FMD within 15 min, suggesting the need for selection of a more adequate interval between measurements to avoid underestimation of FMD in subsequent measurements. The findings demonstrated the reproducibility of FMTD-R and FMTD measurements, and that FMTD-R might be involved in arterial stiffness and early vascular impairment in the healthy subjects

Corowa-kun: A messenger app chatbot delivers COVID-19 vaccine information, Japan 2021.

BACKGROUND: There is a long history in Japan of public concerns about vaccine adverse events. Few studies have assessed how mobile messenger apps affect COVID-19 vaccine hesitancy. METHODS: Corowa-kun, a free chatbot, was created on February 6, 2021 in LINE, the most popular messenger app in Japan. Corowa-kun provides instant, automated answers to 70 frequently asked COVID-19 vaccine questions. A cross-sectional survey with 21 questions was performed within Corowa-kun during April 5-12, 2021. RESULTS: A total of 59,676 persons used Corowa-kun during February-April 2021. Of them, 10,192 users (17%) participated in the survey. Median age was 55 years (range 16-97), and most were female (74%). COVID-19 vaccine hesitancy reported by survey respondents decreased from 41% to 20% after using Corowa-kun. Of the 20% who remained hesitant, 16% (1,675) were unsure, and 4% (364) did not intend to be vaccinated. Factors associated with vaccine hesitancy were: age 16-34 (odds ratio [OR] = 3.7; 95% confidential interval [CI]: 3.0-4.6, compared to age ≥ 65), female sex (OR = 2.4; Cl: 2.1-2.8), and history of a previous vaccine side-effect (OR = 2.5; Cl: 2.2-2.9). Being a physician (OR = 0.2; Cl: 0.1-0.4) and having received a flu vaccine the prior season (OR = 0.4; Cl: 0.3-0.4) were protective. CONCLUSIONS: A substantial number of people used the chabot in a short period. Mobile messenger apps could be leveraged to provide accurate vaccine information and to investigate vaccine intention and risk factors for vaccine hesitancy

Brachial artery characteristics.

<p>Values are mean ± SD.</p><p>p<0.01, compared with the respective baseline measurement.</p

Values of FMD-related indices and CAVI in the healthy subjects divided into the poor and good recovery groups based on the median FMTD-R value (-26.2%).

<p>No significant difference was observed in FMD (A), FMTD (B), and L-FMC (C) values between the two groups. CAVI values were significantly higher in the poor recovery group.</p

Correlation between FMTD-R and other FMD-related indices.

<p>Although a significant correlation between FMTD-R and L-FMC was confirmed (A), no relationship was found between FMTD-R and FMD (B) or FMTD (C). Notably, FMTD-R correlated significantly with CAVI (D).</p

Clinical characteristics of the patient population divided according to FMTD-R.

<p>Values are mean ± SD or percentage of patients.</p><p>*p<0.004, compared with the good FMTD-R group (Fisher's exact probability test).</p