Verification of a New Method in Determining the Visocity of Fluids Under High Temperature and Pressure

At convergent plate boundaries, where plate subduction occurs, volcanism is witnessed above the subducting plate. Hydrous minerals carried to depths of 100 km break down and release their stored water into overlying rock. As this water migrates toward the surface, mantle rock melts and also rises to the surface. This magma is seen as volcanic arcs on the surface. Viscosity measurements are important in the investigation of fluid transport. Previous measurements of water viscosity have been constrained to surface or near surface conditions. The dehydration reactions occur under much higher temperatures and pressures than those found on the surface. Prior to determining viscosity at these high pressures and temperatures (approximately 1300 K and 5 GPa), the method must be validated on fluids having well known viscosities. This is done by calculating the viscosity of water under conditions in which it is already well known (1 atm and 25º C). The hydrothermal diamond cell will be used in the high pressure and temperature experiments. The geometry of the hydrothermal diamond cell must also be reproduced when the method is tested. This geometry can be simply reproduced. Two glass slides were clamped together with a rhenium gasket between the slides. The gasket will be the same type as the one used in the hydrothermal diamond cell. Water with suspended particles was contained within a central gap within. Particle motion was monitored for preferential motion, in order to confirm accurate results. Particles in water exhibit random motions, called Brownian motion. These motions are completely random and by recording their motion, the viscosity of the water can be determined. Care must be taken when choosing the particles to track. Particles in close proximity to each other or to the surface of the gasket do not move randomly due to interactions. Digital recordings are then made of the 3 mm suspended particles. Using mean square displacement, the viscosity can then be calculated from the data

AMO-Forced Regional Processes Affecting Summertime Precipitation Variations in the Central United States

Numerous previous studies have provided insight into the influence of the Atlantic multidecadal oscillation (AMO) on North American precipitation. However, these studies focused on large-scale processes, and additional studies are needed to gain understanding of local and regional processes that develop in different phases of the AMO and substantiate its influences on precipitation. In this study, the Weather Research and Forecasting (WRF) regional model is used to examine AMO-forced local and regional processes and how they have affected summertime precipitation variation in the central United States. While moisture transport and convergence by the Great Plains low-level jet have been recognized as necessary conditions for summer precipitation, model simulations show similar low-level moisture flux convergence in the central United States between the cold and warm phases of the AMO. However, there was a strong moistening in the lower troposphere during the AMO cold phase, making the atmosphere more unstable for convection and precipitation. The source of the moisture was found to be a strong positive surface evaporation–precipitation feedback initiated and sustained by increased relative vorticity along a frontal zone. Along the frontal zone, isentropic stretching of the upper-level atmosphere and cyclonic circulation anomalies increased the relative vorticity during theAMOcold phase, providing the dynamic support needed to release the low-level moist instability and produce the increased precipitation. These results indicate that the dynamics of the circulation in the AMO cold phase played key roles to organize regional vorticity processes that further sustained a coupling of precipitation and the surface evaporation and perpetuated the precipitation

AMO-Forced Regional Processes Affecting Summertime Precipitation Variations in the Central United States

Numerous previous studies have provided insight into the influence of the Atlantic multidecadal oscillation (AMO) on North American precipitation. However, these studies focused on large-scale processes, and additional studies are needed to gain understanding of local and regional processes that develop in different phases of the AMO and substantiate its influences on precipitation. In this study, the Weather Research and Forecasting (WRF) regional model is used to examine AMO-forced local and regional processes and how they have affected summertime precipitation variation in the central United States. While moisture transport and convergence by the Great Plains low-level jet have been recognized as necessary conditions for summer precipitation, model simulations show similar low-level moisture flux convergence in the central United States between the cold and warm phases of the AMO. However, there was a strong moistening in the lower troposphere during the AMO cold phase, making the atmosphere more unstable for convection and precipitation. The source of the moisture was found to be a strong positive surface evaporation–precipitation feedback initiated and sustained by increased relative vorticity along a frontal zone. Along the frontal zone, isentropic stretching of the upper-level atmosphere and cyclonic circulation anomalies increased the relative vorticity during theAMOcold phase, providing the dynamic support needed to release the low-level moist instability and produce the increased precipitation. These results indicate that the dynamics of the circulation in the AMO cold phase played key roles to organize regional vorticity processes that further sustained a coupling of precipitation and the surface evaporation and perpetuated the precipitation

Heterogeneous N2O5 Uptake During Winter: Aircraft Measurements During the 2015 WINTER Campaign and Critical Evaluation of Current Parameterizations

Nocturnal dinitrogen pentoxide (N2O5) heterogeneous chemistry impacts regional air quality and the distribution and lifetime of tropospheric oxidants. Formed from the oxidation of nitrogen oxides, N2O5 is heterogeneously lost to aerosol with a highly variable reaction probability, γ(N2O5), dependent on aerosol composition and ambient conditions. Reaction products include soluble nitrate (HNO3 or NO3−) and nitryl chloride (ClNO2). We report the first‐ever derivations of γ(N2O5) from ambient wintertime aircraft measurements in the critically important nocturnal residual boundary layer. Box modeling of the 2015 Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) campaign over the eastern United States derived 2,876 individual γ(N2O5) values with a median value of 0.0143 and range of 2 × 10−5 to 0.1751. WINTER γ(N2O5) values exhibited the strongest correlation with aerosol water content, but weak correlations with other variables, such as aerosol nitrate and organics, suggesting a complex, nonlinear dependence on multiple factors, or an additional dependence on a nonobserved factor. This factor may be related to aerosol phase, morphology (i.e., core shell), or mixing state, none of which are commonly measured during aircraft field studies. Despite general agreement with previous laboratory observations, comparison of WINTER data with 14 literature parameterizations (used to predict γ(N2O5) in chemical transport models) confirms that none of the current methods reproduce the full range of γ(N2O5) values. Nine reproduce the WINTER median within a factor of 2. Presented here is the first field‐based, empirical parameterization of γ(N2O5), fit to WINTER data, based on the functional form of previous parameterizations

The 3rd Fermi GBM Gamma-Ray Burst Catalog: The First Six Years

Since its launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has triggered and located on average approximately two gamma-ray bursts (GRB) every three days. Here we present the third of a series of catalogs of GRBs detected by GBM, extending the second catalog by two more years, through the middle of July 2014. The resulting list includes 1405 triggers identified as GRBs. The intention of the GBM GRB catalog is to provide information to the community on the most important observables of the GBM detected GRBs. For each GRB the location and main characteristics of the prompt emission, the duration, peak flux and fluence are derived. The latter two quantities are calculated for the 50-300~keV energy band, where the maximum energy release of GRBs in the instrument reference system is observed, and also for a broader energy band from 10-1000 keV, exploiting the full energy range of GBM's low-energy NaI(Tl) detectors. Using statistical methods to assess clustering, we find that the hardness and duration of GRBs are better fitted by a two-component model with short-hard and long-soft bursts, than by a model with three components. Furthermore, information is provided on the settings and modifications of the triggering criteria and exceptional operational conditions during years five and six in the mission. This third catalog is an official product of the Fermi GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center (HEASARC).Comment: 225 pages, 13 figures and 8 tables. Accepted for publication in Astrophysical Journal Supplement 201

Strangeness production at SPS energies

We present a summary of measurements of strange particles performed by the experiment NA49 in central and minimum bias Pb+Pb collisions in the beam energy range 20A - 158A GeV. New results on Xi production in central Pb+Pb collisions and on Lambda, Xi production in minimum bias collisions are shown. Transverse mass spectra and rapidity distributions of strange particles at different energies are compared. The energy dependence of the particle yields and ratios is discussed. NA49 measurements of the Lambda and Xi enhancement factors are shown for the first time.Comment: Submitted to J. Phys. G (Proceedings of the 9th International Conference on Strangeness in Quark Matter, Los Angeles, USA, March 26-31, 2006). 9 pages, 9 figure

Risk Factors for Heart Failure Among Pan-European Childhood Cancer Survivors: A PanCareSurFup and ProCardio Cohort and Nested Case-Control Study.

PURPOSE Heart failure (HF) is a potentially life-threatening complication of treatment for childhood cancer. We evaluated the risk and risk factors for HF in a large European study of long-term survivors. Little is known of the effects of low doses of treatment, which is needed to improve current treatment protocols and surveillance guidelines. METHODS This study includes the PanCareSurFup and ProCardio cohort of ≥ 5-year childhood cancer survivors diagnosed between 1940 and 2009 in seven European countries (N = 42,361). We calculated the cumulative incidence of HF and conducted a nested case-control study to evaluate detailed treatment-related risk factors. RESULTS The cumulative incidence of HF was 2% (95% CI, 1.7 to 2.2) by age 50 years. The case-control study (n = 1,000) showed that survivors who received a mean heart radiation therapy (RT) dose of 5 to < 15 Gy have an increased risk of HF (odds ratio, 5.5; 95% CI, 2.5 to 12.3), when compared with no heart RT. The risk associated with doses 5 to < 15 Gy increased with exposure of a larger heart volume. In addition, the HF risk increased in a linear fashion with higher mean heart RT doses. Regarding total cumulative anthracycline dose, survivors who received ≥ 100 mg/m2 had a substantially increased risk of HF and survivors treated with a lower dose showed no significantly increased risk of HF. The dose-response relationship appeared quadratic with higher anthracycline doses. CONCLUSION Survivors who received a mean heart RT dose of ≥ 5 Gy have an increased risk of HF. The risk associated with RT increases with larger volumes exposed. Survivors treated with < 100 mg/m2 total cumulative anthracycline dose have no significantly increased risk of HF. These new findings might have consequences for new treatment protocols for children with cancer and for cardiomyopathy surveillance guidelines

GRB 221009A, The BOAT

GRB 221009A has been referred to as the Brightest Of All Time (the BOAT). We investigate the veracity of this statement by comparing it with a half century of prompt gamma-ray burst observations. This burst is the brightest ever detected by the measures of peak flux and fluence. Unexpectedly, GRB 221009A has the highest isotropic-equivalent total energy ever identified, while the peak luminosity is at the $\sim99$th percentile of the known distribution. We explore how such a burst can be powered and discuss potential implications for ultra-long and high-redshift gamma-ray bursts. By geometric extrapolation of the total fluence and peak flux distributions GRB 221009A appears to be a once in 10,000 year event. Thus, while it almost certainly not the BOAT over all of cosmic history, it may be the brightest gamma-ray burst since human civilization began.Comment: Resubmitted to ApJ