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When multiple atmospheric rivers (ARs) occur in rapid succession, the combined effect on the hydrologic system can lead to more flooding and damage than would be expected from the individual events. This temporally compounding risk is a source of growing concern for water managers in California. We present a novel moving average‐based definition of AR "sequences" that identifies the time periods of elevated hydrologic hazard that occur during and after consecutive AR events. This marks the first quantitative evaluation of when temporal compounding is contributing to AR flood risk. We also assess projected changes in sequence frequency, intensity, and duration in California using the Geophysical Fluid Dynamics Laboratory Seamless System for Prediction and EArth system Research (GFDL SPEAR) global coupled model. Sequence frequency increases over time and is fairly uniform across the state under both intermediate (SSP2–4.5) and very high (SSP5–8.5) emissions scenarios, with the largest changes occurring by the end of the century (+0.72 sequences/year in SSP2–4.5, +1.13 sequences/year in SSP5–8.5). Sequence intensity and duration both see increases in the medians and extreme values of their respective distributions relative to the historical baselines. In particular, "super‐sequence" events longer than 60 days are projected to occur 2–3x more frequently and to emerge in places that have never seen them in the historical record. In a world where California precipitation is becoming more variable, our definition of sequences will help identify when and where hydrologic impacts will be most extreme, which can in turn support better management of the state's highly variable water resources and inform future flood mitigation strategies. Plain Language Summary: Atmospheric rivers (ARs) are a type of storm that are vital to water resources in the western United States, but can also cause significant flooding and damage. Back‐to‐back AR events have historically been a source of concern for water managers because the compound effect of multiple events together can increase the probability of damaging floods. We present a definition of AR "sequences" that identifies periods of time where the likelihood of compound effects is increased. We look at the relationship between sequences, runoff, and soil moisture in California and show that sequences are in fact aligning with time windows of elevated hydrologic hazard in the historical record. We then look at sequences in two future climate projections and find that sequence frequency, intensity, and duration are all projected to increase with increasing emissions levels. In particular, "super‐sequences" more than 60 days long are projected to become two to three times more frequent across all of California. Our definition of sequences captures and communicates new information about the risk associated with temporally compounding hydrologic events in present and future climates. Key Points: We introduce atmospheric river (AR) sequences as a way to measure the hydrologic hazard from temporally compounding (back‐to‐back) ARsAR sequences in Geophysical Fluid Dynamics Laboratory Seamless System for Prediction and EArth system Research (GFDL SPEAR) model projections increase in frequency, intensity, and duration in California by the end of the century"Super‐sequences" over 60 days long drive the projected increase in frequency and present a growing water management threat in California [ABSTRACT FROM AUTHOR]

This paper describes the analysis of the near-continuum hypersonic flow over a compression ramp using the two-dimensional parallel direct simulation Monte Carlo (DSMC) method. Unstructured and triangular solution-based adaptive mesh depending on the local mean free path is used to improve the resolution of solution for the flow field with highly varying properties. In addition, a freestream parameter is defined to help reduced the cell numbers in the freestream area, resulting in appreciable decrease of the computational time (20-30%) without sacrificing the accuracy of the solution. The two-step multilevel graph partition technique is used for physical domain decomposition, employing estimated particle number distribution in each cell as the graph vertex weight. 32 IBM-SP2 processors are used throughout the study unless otherwise specified. The Effect of the outflow vacuum boundary condition, compression ramp angle, freestream condition, and length of the ramp to the flow field are investigated. Computational results are compared with previous numerical results whenever available. [DOI: 10.1115/1.1523068]

The purpose of this study was to measure the effect of bone-patellar tendon-bone autograft harvest for anterior cruciate ligament (ACL) reconstruction on the surface strain of the human patella. Through progressive removal of bone from the patella, three different defect shapes as well as the intact patella were tested in each of seven knees. Maximum principal strain and corresponding principal direction were determined from each of three gages around the defect for the four conditions (intact plus three defect shapes). There were no statistically significant differences in overall average surface strain between any of the defect shapes. Following graft harvest, overall average strain (all three defects combined) increased in the patella both medial (15 percent increase) and lateral (34 percent increase) to the defect, while decreasing in the region directly proximal (22 percent decrease) to the harvest site compared to the intact patella. A statistically significant 7.5 deg shift of principal direction from longitudinal toward a more transverse (lateral-superior to medial-inferior) direction was observed in the medial region when a shallow-dome defect was made. We conclude that removal of a bone block from the anterior, inferior part of the patella induces a significant redistribution of the surface strain. This results in greater local strain adjacent to the upper border of the bone block, increasing the risk for patella fracture. This effect may be of importance in various complications known to occur after ACL reconstruction.

The temperature effect on the mechanical behavior of the HfNbTaTiZr high entropy alloy (HEA) was investigated at 77–673 K. The decrease of the yield strength with increasing the temperature was mechanistically analyzed by considering contributions from various strengthening mechanisms. An anomalous dependence of strain hardening on temperature was observed and was justified to be caused by dynamic strain aging (DSA) as an extra strengthening mechanism at elevated temperatures. A model was constructed to split the overall strain hardening into forest hardening and DSA hardening, both of which were theoretically quantified at all temperatures considered. The work quantifies the height of Peierls barriers in the bcc HfNbTaTiZr HEA, and reveals dynamic strain aging as the strengthening mechanism causing the anomalous strain hardening at elevated temperatures. [ABSTRACT FROM AUTHOR]

Homogeneous thick film (∼0.10 mm) of high dielectric K0.05Ti0.02Ni0.93O; abbreviated as KTNO/polyvinylidene fluoride (PVDF) composite has been prepared by hot-molding technique. The frequency and temperature dependent dielectric behavior of this composite has been studied by varying the KTNO volume fraction (fKTNO). Near the percolation threshold (fKTNO=0.40), a large enhancement of effective dielectric permittivity ([variant_greek_epsilon]eff∼400 which is 40 times higher than that of pure PVDF) with low loss (∼0.20 at 1 kHz) is observed. The experimental [variant_greek_epsilon]eff data have been fitted with different theoretical models and found to follow percolation theory successfully. Such a high [variant_greek_epsilon]eff and low loss flexible dielectric material appears to be suitable for technological applications. [ABSTRACT FROM AUTHOR]

Ion mobility coupling with mass spectrometer has become an important tool for analysis of complex mixtures. Generally, the type and composition of drift gas (e.g., N2, He, CO2) in an ion mobility spectrometer will impact on the separation of different types of analytes and transmission of ions with a wide mass range. U-shaped mobility analyzer (UMA) is a unique type of mobility device based on counter-flow mobility principle, and it can sort specific types of ions with high mobility resolving power under the co-effect of electric field and gas flow. UMA has independent drift gas channels which allows the drift gas in and out with high speed and accurate control, hence the on-line adjustment of the gas composition becomes possible. The effects of changing drift gas composition on sensitivity, separation capability and analysis speed were examined in this study. From the preliminary results, when using a mixture of drift gas, the mobility peak position (drift field strength) linearly correlated with the gas composition and met the predication of the Blanc′s law. With the constant drift gas velocity, the mobility resolution from He is lower than those from the heavier drift gas (N2 or CO2) based on our theory, but the ion transmission is much higher (better RF confinement in He) and the separation time can also be reduced. On the other hand, if keeping the peak position constant (adjusting drift gas velocity for different gas), the resolution from He can even theoretically surpass that from N2 or CO2 with the expense of sensitivity reduction. Therefore, optimum and balanced results for different applications (e. g. better separation for isomer analysis in N2 or CO2 with doping a specific ratio of He, fast and high sensitivity data acquisition for DDA or DIA operation in pure He) can be achieved by adjusting the drift gas composition. Finally, the possibility and advantages of dynamically controlling the gas composition were discussed, which may provide new perspectives for coupling with LC separation of very complex samples.

Background The relationship between gout medication use and cataract development is controversial. Moreover, limited clinical studies have evaluated this relationship. Aim To assess the effects of colchicine, allopurinol and benzbromarone on the risk of cataract in patients with gout. Design Population-based nested case–control study. Methods We enrolled 7900 patients who had received a new diagnosis of cataract >3 years after gout diagnosis into the study group and 33 475 patients who did not receive a diagnosis of cataract into the control group by matching for age, sex and the year of gout diagnosis at a ratio of 1:1. We used World Health Organization's defined daily dose (DDD) as a measure to assess the dosage of colchicine, allopurinol and benzbromarone exposure. Logistic regression was used to estimate crude and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the risk of cataract. Results The risk of cataract significantly increased in patients who received colchicine at a cumulative DDD of ≥66.5 (OR = 1.17, 95% CI = 1.01–1.36, P  = 0.041). In the age-stratified analysis, patients with gout aged >60 years had a higher risk of cataract (OR = 1.27, 95% CI = 1.06–1.53, P  = 0.011) than did patients aged <60 years. Allopurinol and benzbromarone had no association with cataract. Conclusions In this population-based nested case–control study, we observed that colchicine use increased the risk of cataract in patients with gout, especially in those aged >60 years who received colchicine at a cumulative DDD of >66.5. [ABSTRACT FROM AUTHOR]

Multi-segment cores have been developed by cutting standard MnZn ferrite cores into thin segments and then re-assembling the segments together. All the segments were separated by a thin film of air or insulation materials of microscopic dimensions. The core loss properties of these experimental samples have been investigated between the frequencies of 200 kHz to 2 MHz. The real and imaginary parts of the effective permeability have been determined from these measurements. Experiment results show that the multi-segment ferrite cores are effective in reducing the core loss by possible mechanisms of reduction in the internal electromagnetic field strength and of reduction in the influence of the magnetic skin effect. Index Terms--Core loss, dielectric loss, ferrites, skin effect.

This paper describes a novel compact permanent-magnet synchronous motor with configuration of axial-field slotted windings. It is designed for driving an artificial heart. Both the motor rotor and the pump impeller of the artificial heart are levitated by a magnetic bearing. Structure description, design considerations, and analyses for the motor and bearing are presented in this paper. Index Terms--Artificial heart, axial-field motor, magnetic bearing, permanent-magnet synchronous motor.

A new geometrical design of transcutaneous transformer for artificial heart system is presented in this paper. The primary and secondary cores are made of ferrite and amorphous magnetic materials respectively. The experimental results indicate that it is possible to transmit an electrical power of 20 W which is sufficient to drive the heart pump. With a gap of 5mm between the coils, its transmission efficiency with the inverter can be up to 90% with a switching frequency 102.5kHz. Some characteristics of the proposed transformer are also shown and discussed in this paper. Index Terms--Transcutaneous transformer, artificial heart system, transmission efficiency, flux distribution.

Abstract: The Madden‐Julian Oscillation (MJO) forces strong variations in extratropical atmospheric circulations that have important implications for subseasonal‐to‐seasonal (S2S) prediction. In particular, certain MJO phases are characterized by a consistent modulation of geopotential height in the North Pacific and adjacent regions across different MJO events. Until recently, only limited research has examined the relationship between these robust MJO tropical‐extratropical teleconnections and model prediction skill. In this study, reanalysis data and numerical forecast model ensemble hindcasts are used to demonstrate that robust teleconnections in specific MJO phases and time lags are also characterized by excellent agreement in the prediction of geopotential height anomalies across model ensemble members at forecast leads of up to 3 weeks. These periods of enhanced prediction capabilities extend the possibility for skillful extratropical weather prediction beyond traditional 10–13 day limits. [ABSTRACT FROM AUTHOR]

In this communication, we present experimental evidence of the piezoelectric-field-induced quantum-confined Stark effect on In[sub 0.23]Ga[sub 0.77]N/GaN multiple quantum wells. The optical transitions in In[sub 0.23]Ga[sub 0.77]N/GaN p-i-n multiple quantum wells were studied by using electrotransmission (ET) at room temperature. Quantum-well-related signals are well resolved in our ET spectra. Since the strong internal electric field breaks the symmetry of the quantum wells, both the allowed and the forbidden transitions are observed. Clear energy blueshifts in accordance with increasing reversed bias are observed in ET spectra. The strength of piezoelectric field is found to be 1.7–1.9 MV/cm in the In[sub 0.23]Ga[sub 0.77]N strain quantum well layer, which is comparable with the measurement reported in the literature. We have shown experimentally how the piezoelectric field affects the energy shift for the strained multiple quantum wells. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this paper, we shall establish some extended Simpson-type inequalities for differentiable convex functions and differentiable concave functions which are connected with Hermite-Hadamard inequality. Some error estimates for the midpoint, trapezoidal and Simpson formula are also given. [ABSTRACT FROM AUTHOR]

Glaciers over the Tibetan Plateau have experienced accelerated depletion in the last few decades due primarily to the global warming. The freshwater drained into brackish lakes is also observed by optical remote sensing and altimetry satellites. However, the actual water storage change is difficult to be quantified since the altimetry or remote sensing only provide data in limited dimensions. The altimetry data give an elevation change of surface while the remote sensing images provide an extent variation in horizontal plane. Hence a data set used to describe the volume change is needed to measure the exact mass transition in a time span. In this study, we utilize GRACE gravimetry mission to quantify the total column mass change in the central Tibetan Plateau, especially focused on the lakes near Tanggula Mountains. By removing these factors, the freshwater storage change of glacier system at study area can be potentially isolated. [ABSTRACT FROM AUTHOR]

In this study, graphene colloids were prepared using the electric spark discharge method (ESDM) with graphite rods (99.9% purity) in deionized water (DW) at a normal temperature and pressure. Five different types of graphene colloids were prepared using an electrical discharge machine (EDM) with five different pulse cycle switching times (Ton:Toff ) = 10:10, 30:30, 50:50, 70:70, and 90:90 μs. According to the Ultraviolet-visible spectra (UV-Vis) and Zetasizer analysis, the results showed that the 10:10 μs parameter was the most suitable for the preparation of graphene colloids. UV-Vis was also used to detect the concentration of the graphene colloids; a comparison with a graphene oxide (GO) confirmed that this method could be used to calculate the discharge time needed to produce graphene colloids with different concentrations in the ESDM process.

A forward flow-formed D6ac steel tube was joined through the electron beam welding process and was then subjected to post-weld heat treatment. The mechanical properties and hardness profiles of the as-welded (without heat treatment after welding) steel and different post-weld heat treatment weldments were investigated. The results show that the as-welded D6ac steel exhibited very poor mechanical strength and elongation. After post-weld heat treatment, a large improvement in the mechanical properties of the weldment was achieved. Forward flow-formed D6ac electron beam weldment subjected to post-weld heat treatment at 350°C reached the largest yield strength and ultimate tensile strength values (approximately 1359·2 and 1494·3 MPa, respectively). Forward flow-formed D6ac electron beam weldment subjected to post-weld heat treatment at a temperature of 650°C exhibited an overtempered state, which led to mechanical strength and hardness deteriorations of the weldment. This study found that the forward flow-formed D6ac electron beam weldment heat-treated at 350-450°C and held at this temperature range for 2 h exhibits high mechanical strength, sufficient elongation and a yield strength/ultimate tensile strength ratio of 0·91. [ABSTRACT FROM AUTHOR]