Rates of Relative Sea Level Rise Along the United States East Coast

Recent studies have indicated that some coastal areas, including the East Coast of the United States, are experiencing higher rates of sea level rise than the global average. Rates of relative sea level rise are affected by changes in ocean dynamics, as well as by surface elevation fluctuations due to local land subsidence or uplift. In this study, we derived long-term trends in annual mean relative sea level using tide gauge data obtained from the Permanent Service for Mean Sea Level for stations along the United States East Coast. Stations were grouped by location into the Northeast, Mid-Atlantic, and Southeast regions of the United States East Coast, with the intent of investigating relative sea level rise variability between the three regions. Trends for each region were calculated using stations with a minimum record length of at least 30 years; the longest record began in 1856. Records that were less than 70 percent complete were rejected. For the three-year moving averages, Northeast trends were calculated to be 2.79 mm/yr, Mid-Atlantic trends were calculated to be 4.02 mm/yr, and Southeast trends were calculated to be 2.92 mm/yr. For the five-year moving averages, Northeast trends were calculated to be 2.81 mm/yr, Mid-Atlantic trends were calculated to be 4.04 mm/yr, and Southeast trends were calculated to be 2.91 mm/yr. The Mid-Atlantic region of the United States East Coast was determined to be experiencing significantly higher rates of relative sea level rise than the other regions

Environmental Analysis of Toxic Metals Produced by Cigarette Smoking

Trace metal elements introduced into our environment from anthropogenic sources can become toxic at high levels contributing to a host of human and animal health problems. The purpose of this work is to initially characterize toxic metals present in cigarette tobacco and ash using Electrothermal Atomic Absorption Spectroscopy (ETAAS). The broader impact of this study is to assess the environmental effects of cigarette smoking around designated smoking areas on the Longwood University campus. Smokers may not be informed about the potential harm to the environment from ashing directly on the ground. If the toxic metals present in cigarette ash are not completely volatilized during smoking, they could accumulate over time in the soil adjacent to campus-designated smoking areas. The area surrounding the smoking facilities could, therefore, serve as a starting point for the introduction of toxic metals into the food chain, ground water, or nearby storm water system

Curves of every genus with many points, I: Abelian and toric families

Let N_q(g) denote the maximal number of F_q-rational points on any curve of genus g over the finite field F_q. Ihara (for square q) and Serre (for general q) proved that limsup_{g-->infinity} N_q(g)/g > 0 for any fixed q. In their proofs they constructed curves with many points in infinitely many genera; however, their sequences of genera are somewhat sparse. In this paper, we prove that lim_{g-->infinity} N_q(g) = infinity. More precisely, we use abelian covers of P^1 to prove that liminf_{g-->infinity} N_q(g)/(g/log g) > 0, and we use curves on toric surfaces to prove that liminf_{g-->infty} N_q(g)/g^{1/3} > 0; we also show that these results are the best possible that can be proved with these families of curves.Comment: LaTeX, 20 page

Seasonal changes in soil organic matter after a decade of nutrient addition in a lowland tropical forest

© 2015, US Government. Soil organic matter is an important pool of carbon and nutrients in tropical forests. The majority of this pool is assumed to be relatively stable and to turn over slowly over decades to centuries, although changes in nutrient status can influence soil organic matter on shorter timescales. We measured carbon, nitrogen, and phosphorus concentrations in soil organic matter and leaf litter over an annual cycle in a long-term nutrient addition experiment in lowland tropical rain forest in the Republic of Panama. Total soil carbon was not affected by a decade of factorial combinations of nitrogen, phosphorus, or potassium. Nitrogen addition increased leaf litter nitrogen concentration by 7 % but did not affect total soil nitrogen. Phosphorus addition doubled the leaf litter phosphorus concentration and increased soil organic phosphorus by 50 %. Surprisingly, concentrations of carbon, nitrogen, and phosphorus in soil organic matter declined markedly during the four-month dry season, and then recovered rapidly during the following wet season. Between the end of the wet season and the late dry season, total soil carbon declined by 16 %, total nitrogen by 9 %, and organic phosphorus by between 19 % in control plots and 25 % in phosphorus addition plots. The decline in carbon and nitrogen was too great to be explained by changes in litter fall, bulk density, or the soil microbial biomass. However, a major proportion of the dry-season decline in soil organic phosphorus was explained by a corresponding decline in the soil microbial biomass. These results have important implications for our understanding of the stability and turnover of organic matter in tropical forest soils, because they demonstrate that a considerable fraction of the soil organic matter is seasonally transient, despite the overall pool being relatively insensitive to long-term changes in nutrient status

OpenFOAM Simulations of Atmospheric-Entry Capsules in the Subsonic Regime

The open-source Computational Fluid Dynamics software OpenFOAM is gaining wider acceptance in industry and academia for incompressible flow simulations. To date, there has been relatively little utilization of OpenFOAM for compressible external aerodynamic applications. The numerous turbulence models available in OpenFOAM makes it an attractive option for evaluating alternate Reynolds-Averaged Navier-Stokes (RANS) turbulent models to assess separated flow on atmospheric entry vehicles in the subsonic regime, where traditional turbulent models show reduced accuracy. This paper presents simulations of an axisymmetric capsule geometry at subsonic conditions using an OpenFOAM compressible flow solver. These results are compared with results from the NASA CFD code OVERFLOW and experimental data. These OpenFOAM simulations serve as a basis to explore OpenFOAMs extended turbulence models on compressible separated flows such as found on entry capsules

Simulation of Atmospheric-Entry Capsules in the Subsonic Regime

The accuracy of Computational Fluid Dynamics predictions of subsonic capsule aerodynamics is examined by comparison against recent NASA wind-tunnel data at high-Reynolds-number flight conditions. Several aspects of numerical and physical modeling are considered, including inviscid numerical scheme, mesh adaptation, rough-wall modeling, rotation and curvature corrections for eddy-viscosity models, and Detached-Eddy Simulations of the unsteady wake. All of these are considered in isolation against relevant data where possible. The results indicate that an improved predictive capability is developed by considering physics-based approaches and validating the results against flight-relevant experimental data

Effectiveness of Cabs for Dust and Silica Control on Mobile Mining Equipment

The Mine Safety and Health Administration (MSHA) has conducted a study to evaluate the effectiveness of cabs for controlling silica dust exposure during operation of mobile mining equipment. This study focused on bulldozers, front -end loaders and haul trucks, was conducted at surface coal mining operations and underground metal and nonmetal mining operations. Each piece of equipment tested was equipped with a cab. The vehicles sampled were from a range of manufacturers having different types of filter media and air intake configurations. The purpose of this study was to determine the reduction of dust and silica exposure that could be achieved through the use of a well-maintained cab. For each piece of equipment, dust and silica concentrations inside and outside the cab were determined and compared. In some cases, filtration efficiencies could be calculated. A properly designed environmental cab is sealed, has an intake air filtration system, and a heating and cooling system. Cabs should have good seals around the doors and windows. Factors such as cab pressurization filtration systems, filter media, and maintenance practices were also examined. In some cases, dust and silica reduction of 90 to 95% were observed

Effects of the Orion Launch Abort Vehicle Plumes on Aerodynamics and Controllability

Characterization of the launch abort system of the Multi-purpose Crew Vehicle (MPCV) for control design and accurate simulation has provided a significant challenge to aerodynamicists and design engineers. The design space of the launch abort vehicle (LAV) includes operational altitudes from ground level to approximately 300,000 feet, Mach numbers from 0-9, and peak dynamic pressure near 1300psf during transonic flight. Further complicating the characterization of the aerodynamics and the resultant vehicle controllability is the interaction of the vehicle flowfield with the plumes of the two solid propellant motors that provide attitude control and the main propulsive impulse for the LAV. These interactions are a function of flight parameters such as Mach number, altitude, dynamic pressure, vehicle attitude, as well as parameters relating to the operation of the motors themselves - either as a function of time for the AM, or as a result of the flight control system requests for control torque from the ACM. This paper discusses the computational aerodynamic modeling of the aerodynamic interaction caused by main abort motor and the attitude control motor of the MPCV LAV, showing the effects of these interactions on vehicle controllability