Terrestrial planets currently in the habitable zones around M dwarfs likely experienced a long-term runaway-greenhouse condition because of a slow decline in host-star luminosity in its pre-main-sequence phase. Accordingly, they might have lost significant portions of their atmospheres including water vapor at high concentration by hydrodynamic escape induced by the strong stellar X-ray and extreme ultraviolet (XUV) irradiation. However, the atmospheric escape rates remain highly uncertain due partly to a lack of understanding of the effect of radiative cooling in the escape outflows. Here we carry out 1D hydrodynamic escape simulations for an H2–H2O atmosphere on a planet with mass of 1M ⊕ considering radiative and chemical processes to estimate the atmospheric escape rate and follow the atmospheric evolution during the early runaway-greenhouse phase. We find that the atmospheric escape rate decreases with the basal H2O/H2 ratio due to the energy loss by the radiative cooling of H2O and chemical products such as OH and OH+: the escape rate of H2 becomes one order of magnitude smaller when the basal H2O/H2 = 0.1 than that of the pure hydrogen atmosphere. The timescale for H2 escape exceeds the duration of the early runaway-greenhouse phase, depending on the initial atmospheric amount and composition, indicating that H2 and H2O could be left behind after the end of the runaway-greenhouse phase. Our results suggest that temperate and reducing environments with oceans could be formed on some terrestrial planets around M dwarfs.
PurposeTo diagnose glaucoma based on spectral domain optical coherence tomography (SD-OCT) measurements using the ‘Random Forests’ method.MethodsSD-OCT was conducted in 126 eyes of 126 open angle glaucoma (OAG) patients and 84 eyes of 84 normal subjects. The Random Forests method was then applied to discriminate between glaucoma and normal eyes using 151 OCT parameters including thickness measurements of circumpapillary retinal nerve fiber layer (cpRNFL), the macular RNFL (mRNFL) and the ganglion cell layer-inner plexiform layer combined (GCIPL). The area under the receiver operating characteristic curve (AROC) was calculated using the Random Forests method adopting leave-one-out cross validation. For comparison, AROCs were calculated based on each one of the 151 OCT parameters.ResultsThe AROC obtained with the Random Forests method was 98.5% [95% Confidence interval (CI): 97.1–99.9%], which was significantly larger than the AROCs derived from any single OCT parameter (maxima were: 92.8 [CI: 89.4–96.2] %, 94.3 [CI: 91.1–97.6] % and 91.8 [CI: 88.2–95.4] % for cpRNFL-, mRNFL- and GCIPL-related parameters, respectively; P<0.05, DeLong’s method with Holm’s correction for multiple comparisons). The partial AROC above specificity of 80%, for the Random Forests method was equal to 18.5 [CI: 16.8–19.6] %, which was also significantly larger than the AROCs of any single OCT parameter (P<0.05, Bootstrap method with Holm’s correction for multiple comparisons).ConclusionsThe Random Forests method, analyzing multiple SD-OCT parameters concurrently, significantly improves the diagnosis of glaucoma compared with using any single SD-OCT measurement.
In this work, an ultrafast spectral diffusion of the lowest exciton in a tetracene ultrathin film is studied by two-dimensional electronic spectroscopy. From the analysis of the nodal line slope, the frequency-fluctuation correlation function (FFCF) of the exciton band is extracted. The FFCF contains two components with decay times of 400 and 80 fs; while the former can be understood by a linear exciton–phonon coupling model, the latter shows an order of magnitude increase in its amplitude from 96 to 186 K that cannot be explained by the same model. A novel scheme of the energy-gap fluctuations is examined, in which an intramolecular high-frequency mode causes the spectral diffusion that is enhanced through an anharmonic coupling to low-frequency phonon modes. This finding provides a valuable input for future theoretical predictions on the ultrafast nonadiabatic dynamics of the molecular exciton.
High-pressure operation through high strength linepipe reduces long distance transportation cost of natural gas. In order to maximize the cost reduction, X120 UOE pipe has been developed. Low C-Mo-B steel with fine-grained lower bainite (LB) microstructure realizes high strength, excellent low temperature toughness and good weldability. The technology was verified in small-scale commercial production or “mini-rolls”. Suitability for use as linepipe was demonstrated through an extensive development program that covers burst test, fracture toughness evaluation, girth welding technology, etc. A demonstration line was successfully constructed using the pipes manufactured in the “mini-rolls”.
A series of undrained cyclic torsional shear tests was conducted to investigate liquefaction properties of Toyoura sand under low confining stress. Hollow-cylindrical specimens were prepared by air pluviation at a relative density of about 55%. After being saturated, they were anisotropically consolidated to an effective vertical stress of 9.8, 29.4 and 98.1 kPa, while keeping the effective horizontal stress to be half of the vertical one. They were subjected to undrained cyclic torsional shear without allowing any vertical displacement of the top cap. The amplitude of the cyclic shear stress was kept constant with correction for the effects of membrane force on the measured values. The liquefaction resistance was found to increase with the decrease in the confining stress, while correction for the effects of membrane penetration did not significantly affect this tendency. Analyses of the test results revealed that the liquefaction properties were affected by the mobilization of shear resistance under extremely low effective stress states and the stress level-dependency of shear modulus that was normalized by the confining stress. Finally, by introducing a concept of apparent increase in the effective mean principal stress, a simplified procedure to estimate the liquefaction resistance under low confining stresses was proposed.
The workcation, wherein people combine work with vacation, is a concept that originated in the United States and Europe with the spread of information and communications technology (ICT). Although it is considered a workstyle for independent people as epitomized by freelancers and the like, in Japan, the term has come to convey something different from its original meaning, taking a unique direction in which some types of training programs are referred to as workcation. How did this change come about? This study, based on surveys of three regions, examines the origin and development of satellite office workcation and learning workcation to ascertain the following. (1) In Japan, people with workcation are assumed to be employees. (2) Therefore, the workcation is heavily influenced by local governments' intentions (wanting to associate with exchange populations) and companies' intentions (it is difficult to dispatch employees to outlying areas without a work-related purpose). (3) Therefore, the workcation has evolved into something that aims to enhance creativity, learning, and introspection through close ties with communities.
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