Frictional experiments of dolerite at intermediate slip rates with controlled temperature: Rate weakening or temperature weakening?

A rotary shear apparatus has been newly set up in Chiba University which can control the temperature near a sliding surface, T_meas, up to 1000°C independently from slip rate, V. Frictional experiments at 0.010 m/s, 1 MPa normal stress, and variable T_meas for dolerite have revealed a remarkable effect of temperature on the friction coefficient, f. With increasing T_meas, f starts from 0.7 to 0.8 at room temperature (RT), decreases down to 0.5–0.6 at 400°C, increases until 800°C, and then decreases again. We have also conducted XRD analyses of the wear materials (mainly submicron particles) and investigated microstructures of the sliding surfaces developed at different temperatures T_meas, and we found that there is a negative correlation between f and the amount of amorphous material except at RT and 1000°C. The generation of the amorphous phase probably causes the weakening. There is no amorphous phase recognized for a sample at 1000°C which is an aggregate of rounded crystals. EBSD analyses show that the material on the sliding surface at 1000°C contains randomly oriented hematite grains, which together with the observed microstructural features suggests that granular flow was taking place. We have also demonstrated that f depends not only on the instantaneous value of temperature, but also on its history. By comparing with conventional rotary shear friction experiment for the same dolerite without temperature control, we conclude that strong “rate weakening” as recently observed in high-velocity frictional experiments without an active control of the temperature has a significant amount of contribution from the temperature effect

Low- to high-velocity frictional properties of the clay-rich gouges from the slipping zone of the 1963 Vaiont slide, northern Italy

The final slip of about 450 m at about 30 m/s of the 1963 Vaiont landslide (Italy) was preceded by >3 year long creeping phase which was localized in centimeter-thick clay-rich layers (60–70% smectites, 20–30% calcite and quartz). Here we investigate the frictional properties of the clay-rich layers under similar deformation conditions as during the landslide: 1–5 MPa normal stress, 2 × 10^(−7) to 1.31 m/s slip rate and displacements up to 34 m. Experiments were performed at room humidity and wet conditions with biaxial, torsion and rotary shear apparatus. The clay-rich gouge was velocity-independent to velocity-weakening in both room humidity and wet conditions. In room humidity experiments, the coefficient of friction decreased from 0.47 at v 0.70 m/s: full lubrication results from the formation of a continuous water film in the gouge. The Vaiont landslide occurred under wet to saturated conditions. The unstable behavior of the landslide is explained by the velocity-weakening behavior of the Vaiont clay-rich gouges. The formation of a continuous film of liquid water in the slipping zone reduced the coefficient of friction to almost zero, even without invoking the activation of thermal pressurization. This explains the extraordinary high velocity achieved by the slide during the final collapse

The circulation pattern and day-night heat transport in the atmosphere of a synchronously rotating aquaplanet: Dependence on planetary rotation rate

In order to investigate a possible variety of atmospheric states realized on a synchronously rotating aquaplanet, an experiment studying the impact of planetary rotation rate is performed using an atmospheric general circulation model (GCM) with simplified hydrological and radiative processes. The entire planetary surface is covered with a swamp ocean. The value of planetary rotation rate is varied from zero to the Earth’s, while other parameters such as planetary radius, mean molecular weight and total mass of atmospheric dry components, and solar constant are set to the present Earth’s values. The integration results show that the atmosphere reaches statistically equilibrium states for all runs; none of the calculated cases exemplifies the runaway greenhouse state. The circulation patterns obtained are classified into four types: Type-I characterized by the dominance of a day-night thermally direct circulation, Type-II characterized by a zonal wave number one resonant Rossby wave over a meridionally broad westerly jet on the equator, Type-III characterized by a long time scale north-south asymmetric variation, and Type-IV characterized by a pair of mid-latitude westerly jets. With the increase of planetary rotation rate, the circulation evolves from Type-I to Type-II and then to Type-III gradually and smoothly, whereas the change from Type-III to Type-IV is abrupt and discontinuous. Over a finite range of planetary rotation rate, both Types-III and -IV emerge as statistically steady states, constituting multiple equilibria. In spite of the substantial changes in circulation, the net energy transport from the day side to the night side remains almost insensitive to planetary rotation rate, although the partition into dry static energy and latent heat energy transports changes. The reason for this notable insensitivity is that the outgoing longwave radiation over the broad area of the day side is constrained by the radiation limit of a moist atmosphere, so that the transport to the night side, which is determined as the difference between the incoming solar radiation and the radiation limit, cannot change greatly

Efficacy of ezetimibe as monotherapy or combination therapy in hypercholesterolemic patients with and without diabetes

Ezetimibe selectively inhibits dietary and biliary cholesterol absorption and reduces serum cholesterol levels when administered alone (monotherapy) and along with common lipid-regulating agents (combination therapy). To evaluate the effect of ezetimibe therapy on the lipid profile, glucose metabolism, and levels of cholesterol absorption and synthesis markers, we administered 10 mg ezetimibe to 50 hypercholesterolemic patients with or without diabetes. The serum levels of low-density lipoprotein cholesterol and total cholesterol were significantly reduced at 4 and 12 weeks of ezetimibe therapy in diabetic patients of both the monotherapy and combination-therapy groups and in nondiabetic patients of the combination-therapy group. The serum levels of the cholesterol absorption markers were significantly reduced, while those of the cholesterol synthesis markers were significantly increased at 12 weeks of ezetimibe therapy. No significant differences were noted in the values of the parameters of glucose metabolism in all patients. We also investigated the clinical characteristics of patients who exhibited a good response to ezetimibe (ezetimibe responders) ; however, multivariate regression analysis did not reveal a correlation between ezetimibe efficacy and patient characteristics such as gender, age, BMI, diabetic condition, method of ezetimibe administration, and the initial absolute values of cholesterol absorption/synthesis markers levels. In conclusion, ezetimibe therapy significantly improved the lipid profile without disturbing glucose metabolism. We were unable to identify the specific characteristics of ezetimibe responders among our subjects. However, we may interpret this result as suggesting that ezetimibe can be used in any population to lower low-density lipoprotein cholesterol levels

Proposal and Demonstration of Free-Space Optical Communication Using Photonic Crystal Surface-Emitting Lasers

We propose and demonstrate free-space optical (FSO) communication using photonic crystal surface-emitting lasers (PCSELs). Unlike other types of conventional semiconductor lasers, such as edge-emitting lasers (EELs) and vertical-cavity surface-emitting lasers (VCSELs), PCSELs achieve much larger area single-mode coherent lasing, and this unique feature enables high-power (>watt) and lens-free operations at the same time. To date, these advantages have been recognized to be game changing, especially in light detection and ranging (LiDAR) and laser processing applications. In this work, we show that FSO communication can also benefit from these advantages of PCSELs; more specifically, conventional transmitters that include low-power semiconductor lasers, optical lenses, and fiber-based amplifiers could be replaced with a single PCSEL. Since fiber amplifiers usually consist of bulky components and have low conversion efficiencies, PCSELs can offer more space- and power-saving solutions. Moreover, the narrow beam divergence angles directly obtained from large-area single-mode PCSELs can also eliminate the need for lens systems on the transmitter side. To experimentally verify these potential advantages, we performed FSO transmission experiments based on PCSELs and successfully transmitted 480-MHz and 864-MHz orthogonal frequency division multiplexed (OFDM) signals over 1.1 m using a 500-μm PCSEL in a lens-free transmitter configuration. We believe that PCSELs open new possibilities and choices in FSO communication

Difference between carbohydrate antigen 19-9 and fluorine-18 fluorodeoxyglucose positron emission tomography in evaluating the treatment efficacy of neoadjuvant treatment in patients with resectable and borderline resectable pancreatic ductal adenocarcinoma: Results of a dual-center study

kita, H, Takahashi, H, Eguchi, H, et al. Difference between carbohydrate antigen 19‐9 and fluorine‐18 fluorodeoxyglucose positron emission tomography in evaluating the treatment efficacy of neoadjuvant treatment in patients with resectable and borderline resectable pancreatic ductal adenocarcinoma: Results of a dual‐center study. Ann Gastroenterol Surg. 2020; 00: 1– 9. https://doi.org/10.1002/ags3.12418

Clinicopathological Features and Outcomes of Endoscopic Submucosal Dissection for Superficial Cancer of the Pharynx

The efficacy and safety of endoscopic submucosal dissection (ESD) for superficial cancer of the pharynx are still unclear. To identify clinicopathological features of superficial pharyngeal cancer, and the efficacy and safety of ESD, we retrospectively assessed 70 pharyngeal cancers in 59 patients who underwent ESD. Of these patients, 61.0% and 50.8% had a history of esophageal cancer and head and neck cancer, respectively. The median tumor size was 15 mm, and 75.7% of the lesions were located at the piriform sinus. The en bloc resection rate was 94.9%. Treatment-related adverse events occurred in 8 cases, but there was no treatment-related death. The lateral margin was positive for neoplasm in 3 lesions (4.3%) and inconclusive in 27 lesions (38.6%), but no local recurrence was observed. Cervical lymph node metastasis was observed in 6 patients, and was successfully treated by cervical lymph node dissection. The three-year overall survival rate was 91.5% (95%CI: 76.6-97.3%) and the cause-specific survival rate was 97.6% (95%CI: 84.9-99.7%). In conclusion, ESD for superficial pharyngeal cancer was safe and effective. “Resect and watch” is probably a feasible and rational strategy for treatment of patients with superficial pharyngeal cancer