Comparison of Baseline Covariate Adjustment Methods for Restricted Mean Survival Time

The restricted mean survival time is a clinically easy-to-interpret measure that does not require any assumption of proportional hazards. We focus on two ways to directly model the survival time and adjust the covariates. One is to calculate the pseudo-survival time for each subject using leave-one-out, and then perform a model analysis using all pseudo-values to adjust for covariates. The pseudo-survival time is used to reflect information of censored subjects in the model analysis. The other method adjusts for covariates using subjects for whom the time-to-event was observed while adjusting for the censored subjects using the inverse probability of censoring weighting (IPCW). This paper evaluates the performance of these two methods in terms of the power to detect group differences through a simple example dataset and computer simulations. The simple example illustrates the intuitive behavior of the two methods. With the method using pseudo-survival times, it is difficult to interpret the pseudo-values. We confirm that the pseudo-survival times are different from the actual data obtained in a primary biliary cholangitis clinical trial because of the many censored data. In the simulations, the method using IPCW is found to be more powerful. Even in the case of group differences with respect to the censor incidence rates and covariates, the method using IPCW maintains a nominal significance level for the type-1 error rate. We conclude that the IPCW method should be used to estimate the restricted mean survival time when adjusting the covariates

Tsunami Hazard Assessment for the Hokuriku Region, Japan: Toward Disaster Mitigation for Future Earthquakes

In Japan, compared with the Pacific coast, the Japan Sea coast has low seismicity and has experienced very few occurrences of historical tsunami damage. These characteristics lead to some difficulties in the promotion of disaster prevention education, because the Japan Sea coast has not often been threatened by earthquakes and tsunamis. In our study, focusing on the Hokuriku region in Japan, we conducted a tsunami simulation and examined the resulting tsunami hazard map. Three potential faults of Mw7.6 earthquake were selected to generate the tsunami. In addition, we calculated these three events with Mw7.8, given the inherent uncertainty in source parameters. Aside from tsunami height, arrival time, inundation height, and inundation area, we calculated the seismic intensity and the liquefaction occurrence rate by simplified methods. Our results indicated that Suzu City in Ishikawa Prefecture, located in the northeastern part of the Noto Peninsula, has a relatively high potential risk of tsunami as well as strong motion and liquefaction. Thus, Suzu City would represent a highly appropriate area in which to promote disaster prevention education in the Hokuriku region

Noble gas signatures of Antarctic nakhlites, Yamato (Y) 000593, Y000749, and Y000802

We have measured noble gases in three nakhlites from Antarctica, Yamato (Y) 000593, Y000749, and Y000802, by step-heating and total-melting methods.The trapped ^Ar/^Kr/^Xe ratios determined for the bulk samples are around 80/3/1, identical to those of Nakhla. The Yamato nakhlites also release noble gases showing high ^Xe/^Xe (up to 1.486) and low ^Kr/^Xe (～1.5) at 1000 and 1300 ℃, which is one of the most characteristic signatures of nakhlites. The low ^Kr/^Xe, as compared to that of the Mars atmosphere, suggests the presence of a fractionated Martian atmosphere.Cosmic-ray exposure ages based on cosmogenic ^Ne are 11.7, 11.9, and 13.0 Ma for Y000593, Y000749, and Y000802, respectively. This supports the pairing based on the mineralogical and petrographical similarities and the location of the finds. The average of the ^Ne exposure ages is 12.05±0.69 Ma. We also calculated an apparent ^Kr-Kr age as 11.8±1.0 Ma from cosmic-ray produced radioactive ^Kr and stable Kr isotopes from Y000593. The coincidence with the ^Ne exposure age indicates a short terrestrial age (Ne exposure age and terrestrial age, is 12.1±0.7 Ma. Calculated K-Ar gas retention age for the Yamato nakhlites is 1.24±0.22 Ga. The ejection time and gas retention age are close to those of non-Antarctic nakhlites and Chassigny. This suggests that the Yamato nakhlites were ejected from Mars together with other nakhlites and Chassigny. Xenon isotopes are mixtures of Chassigny Xe, fission Xe, and the Mars atmosphere. High-temperature fractions (1000-1750℃) are enriched in the Mars atmosphere and fission Xe components, compared to lower temperature fractions. There are similarities in Xe isotopes between Y000749 and Y000802 showing excesses in ^Xe and ^Xe, whereas Y000593 has only small excesses. The release pattern of ^Xe for Y000593 is also dif

Kinematic modeling and error sensitivity analysis for on-machine five-axis laser scanning measurement under machine geometric errors and workpiece setup errors

On-machine scanning measurement of workpiece geometry has a strong advantage in its efficiency, compared to conventional discrete measurement using a touch-trigger probe. When a workpiece is rotated and tilted, position and orientation errors of the workpiece with respect to the machine’s rotary axes can be a significant contributor to the measurement error. Rotary axis geometric errors also influence the measurement error. To establish the traceability of on-machine measurement with workpiece rotation, this paper kinematically formulates their contribution to measured profiles. As a practical application example, this paper presents the measurement error assessment for an axis-symmetric part. Based on the present kinematic model, this paper compares error contributors to the cases (1) where an axis-symmetric part is placed concentric to the rotary axis, and (2) where it is placed away from the rotary axis

Nonlinearity-Tolerant Modulation Formats for Coherent Optical Communications

Fiber nonlinearity is the main factor limiting the transmission distance of coherent optical communications. We overview several modulation formats intrinsically tolerant to fiber nonlinearity. We recently proposed family of 4D modulation formats based on 2-ary amplitude 8-ary phase-shift keying (2A8PSK), covering the spectral efficiency of 5, 6, and 7 bits/4D symbol, which will be explained in detail in this chapter. These coded modulation formats fill the gap of spectral efficiency between DP-QPSK and DP-16QAM, showing superb performance both in linear and nonlinear regimes. Since these modulation formats share the same constellation and use different parity bit expressions only, digital signal processing can accommodate those multiple modulation formats with minimum additional complexity. Nonlinear transmission simulations indicate that these modulation formats outperform the conventional formats at each spectral efficiency. We also review DSP algorithms and experimental results. Their application to time-domain hybrid modulation for 4–8 bits/4D symbol is also reviewed. Furthermore, an overview of an eight-dimensional 2A8PSK-based modulation format based on a Grassmann code is also given. All these results indicate that the 4D-2A8PSK family show great promise of excellent linear and nonlinear performances in the spectral efficiency between 3.5 and 8 bits/4D symbol

Small sensor probe for measuring plasma waves in space Space science

Background: Since conventional one-point observations of plasma phenomena in space cannot distinguish between time and spatial variations, the missions on the basis of multiple-point observations have become the trend. We propose a new system for multiple-point observation referred to as the monitor system for space electromagnetic environments (MSEE). Findings: The MSEE consists of small sensor probes that have a capability to measure electromagnetic waves and transfer received data to the central station through wireless communication. We developed the prototype model of the MSEE sensor probe. The sensor probe includes a plasma wave receiver, the microcontroller, the wireless communication module, and the battery in the 75-mm cubic housing. In addition, loop antennas, dipole antennas, and actuators that are used for expanding dipole antennas are attached on the housing. The whole mass of the sensor probe is 692 g, and the total power consumption is 462 mW. The sensor probe can work with both inner battery and external power supply. The maximum continuous operation time on battery power is more than 6 h. We verified the total performance for electric field measurements by inputting signal to preamplifier. In this test, we found that analog components had enough characteristics to measure electric fields, and the A/D conversion and the wireless transmission worked correctly. In the whole performance for electric fields, the sensor probe has equivalent noise level of - 135 dBV/m/√Hz. Conclusions: We succeed in developing the prototype model of the small sensor probe that had enough sensitivity for electric field to measure plasma waves and the ability to transfer observation data through wireless communication. The success in developing the small sensor probe for the measurement of plasma waves leads to the realization of the multiple-point observations using a lot of small probes scattered in space