Can a gravitational wave and a magnetic monopole coexist?

We investigate the behavior of small perturbations around the Kaluza-Klein monopole in the five dimensional space-time. We find that the even parity gravitational wave does not propagate in the five dimensional space-time with Kaluza-Klein monopole provided that the gravitational wave is constant in the fifth direction. We conclude that a gravitational wave and a U(1) magnetic monopole do not coexist in five dimensional Kaluza-Klein spacetime.Comment: 10 pages, LaTeX. To appear in Modern Physics Letters

Thermomechanical noise of arrayed capacitive accelerometers with 300-NM-gap sensing electrodes

2017 19th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), 18-22 June 2017.Thermomechanical noise of arrayed capacitive accelerometers with sub-micrometer sensing electrodes was evaluated. The unit accelerometer of the array was 80-μm square, designed as a proportional scale-down of a conventional single-axis accelerometer. Since the size effect shows the capacitance sensitivity per unit volume increases by proportional downsizing, a 10-by-10 array of the one-tenth sized unit accelerometer would have the same sensitivity of a single accelerometer of same occupied area. However, the thermomechanical noise needs to be controlled and reduced by vacuum encapsulation because size reduction causes noise increase. By measuring the electrical impedance at the resonant frequency, the damping coefficient was estimated using electrical equivalent circuit modeling. The estimated thermomechanical noise was reduced below 3 μg√VHZ by encapsulating at 100 Pa, which is low enough for instrumentation applications

Zernike generation with MEMS deformadle mirror actuated by electrostatic piston array

2018 IEEE Micro Electro Mechanical Systems (MEMS), 21-25 Jan. 2018.We report a low-voltage and large-displacement electrostatic deformable mirror for in vivo retinal imaging by adaptive-optics optical coherence tomography. The mirror utilizes an electrostatic piston actuator which allows bottom electrodes to move vertically to keep the gap small to maintain large actuation force at low actuation voltage. An 8-mm-diameter mirror device was fabricated from two components; the mirror part and the actuator part. The parts were assembled with 7-μm-gap defined by an SU-8 layer. We successfully demonstrated operation of the mirror in various Zernike modes

Electrostatic Micro Mirror Array with Batch-Fabricated Torsion Beam of Silicon Nanowire

2020 IEEE 33rd International Conference on Micro Electro Mechanical Systems (MEMS), 18-22 Jan. 2020.A new design of arrayed micro mirror device for a high performance spatial light modulator of high resonant frequency, large deflection angle with high mechanical reliability has been proposed. The mirror has 100-μm square plate of 5 μm thick, which is suspended by thin silicon nanowire of about 1 μm thick and wide. The device was fabricated using Bosch process and isotropic plasma etching. We successfully demonstrated array operation of 4×4 devices at relatively low actuation voltage (~20 Vpp) and large mechanical deflection amplitude (~9°). However, the deviation of vibration amplitude was large among unit resonators. By fitting the frequency response to the Duffing equation we found that self-enhancing actuation force caused by nonlinearity of the vertical combs was a main reason

Fracture behavior of single crystal silicon with thermal oxide layer

This paper reports on the effect of oxidation on fracture behavior of single crystal silicon (SCS). SCS specimens were fabricated from (1. 0. 0) silicon-on-insulator wafer with 5-μm-thick device layer and oxide layer were thermally grown. Quasi-static tensile testing of as-fabricated, oxidized and oxidized layer removed specimens was performed. The fracture origin location transited from the surface to silicon/oxide interface and inside of silicon. The transition may be caused by surface smoothing, thickening oxide layer and formation of oxide precipitation defects in silicon during oxidation. The radius of the oxide precipitation defects was estimated, which is well agreed with the fracture-initiating crack sizes

Integrated-gut-liver-on-a-chip platform as an in vitro human model of non-alcoholic fatty liver disease

非アルコール性脂肪性肝疾患を再現した腸・肝連結臓器チップの開発. 京都大学プレスリリース. 2023-04-07.Two-organ chip to answer fatty liver questions. 京都大学プレスリリース. 2023-04-07.Non-alcoholic fatty liver disease (NAFLD) afflicts a significant percentage of the population; however, no effective treatments have yet been established because of the unsuitability of in vitro assays and animal experimental models. Here, we present an integrated-gut-liver-on-a-chip (iGLC) platform as an in vitro human model of the gut-liver axis (GLA) by co-culturing human gut and liver cell lines interconnected via microfluidics in a closed circulation loop, for the initiation and progression of NAFLD by treatment with free fatty acids (FFAs) for 1 and 7 days, respectively. Co-cultured Caco-2 gut-mimicking cells and HepG2 hepatocyte-like cells demonstrate the protective effects from apoptosis against FFAs treatment, whereas mono-cultured cells exhibit induced apoptosis. Phenotype and gene expression analyses reveal that the FFAs-treated gut and liver cells accumulated intracellular lipid droplets and show an increase in gene expression associated with a cellular response to copper ions and endoplasmic reticulum stress. As an in vitro human GLA model, the iGLC platform may serve as an alternative to animal experiments for investigating the mechanisms of NAFLD

FGF2 Has Distinct Molecular Functions from GDNF in the Mouse Germline Niche

Both glial cell line-derived neurotrophic factor (GDNF) and fibroblast growth factor 2 (FGF2) are bona fide self-renewal factors for spermatogonial stem cells, whereas retinoic acid (RA) induces spermatogonial differentiation. In this study, we investigated the functional differences between FGF2 and GDNF in the germline niche by providing these factors using a drug delivery system in vivo. Although both factors expanded the GFRA1+ subset of undifferentiated spermatogonia, the FGF2-expanded subset expressed RARG, which is indispensable for proper differentiation, 1.9-fold more frequently than the GDNF-expanded subset, demonstrating that FGF2 expands a differentiation-prone subset in the testis. Moreover, FGF2 acted on the germline niche to suppress RA metabolism and GDNF production, suggesting that FGF2 modifies germline niche functions to be more appropriate for spermatogonial differentiation. These results suggest that FGF2 contributes to induction of differentiation rather than maintenance of undifferentiated spermatogonia, indicating reconsideration of the role of FGF2 in the germline niche

Sex- and Age-Related Differences in Morbidity Rates of 2009 Pandemic Influenza A H1N1 Virus of Swine Origin in Japan

BACKGROUND: The objective of the present study was to determine whether the morbidity rates of the 2009 pandemic influenza A H1N1 virus (pdmH1N1) varied by age and/or sex. METHODS AND FINDINGS: Retrospective analysis of 2,024,367 cases of pdmH1N1 was performed using the national surveillance data from influenza sentinel points in Japan. The male-to-female morbidity ratios (M/F ratios) in nineteen age groups were estimated as the primary outcome. The M/F ratios for pdmH1N1 influenza were: >1 in age groups <20 years and ≥80 years (p<0.001); <1 in age groups 20-79 years (p<0.001). This data suggests that males <20 years of age may be more likely to suffer from pdmH1N1 influenza than females in the same age categories. When the infection pattern for pdmH1N1 was compared with that of seasonal influenza outbreaks between 2000 and 2008, the M/F ratio for pdmH1N1 influenza was higher in ages 3-29 years and lower in ages 40-79 years. Because the present study was based on the national surveillance, it was impossible to estimate the morbidity rate for the Japanese population. It is also likely that the data did not capture asymptomatic or mild infections. CONCLUSIONS: Although exposure to the pdmH1N1 virus is assumed to be similar in both boys and girls, M/F ratios were >1 in those younger than 20 years. The subsequent reversal of the M/F ratio in the adult generation could be due to several possibilities, including: greater immunity among adult males, more asymptomatic infections among males, less reporting of illness by males, or differences in exposure to the virus and probability of visiting a clinic. These results suggest that the infection and virulence patterns of pdmH1N1 are more complex than previously considered