6,291 research outputs found

    Determination of lunar ilmenite abundances from remotely sensed data

    Get PDF
    The mineral ilmenite (FeTiO3) was found in abundance in lunar mare soils returned during the Apollo project. Lunar ilmenite often contains greater than 50 weight-percent titanium dioxide (TiO2), and is a primary potential resource for oxygen and other raw materials to supply future lunar bases. Chemical and spectroscopic analysis of the returned lunar soils produced an empirical function that relates the spectral reflectance ratio at 400 and 560 nm to the weight percent abundance of TiO2. This allowed mapping of the lunar TiO2 distribution using telescopic vidicon multispectral imaging from the ground; however, the time variant photometric response of the vidicon detectors produced abundance uncertainties of at least 2 to 5 percent. Since that time, solid-state charge-coupled device (CCD) detector technology capable of much improved photometric response has become available. An investigation of the lunar TiO2 distribution was carried out utilizing groundbased telescopic CCD multispectral imagery and spectroscopy. The work was approached in phases to develop optimum technique based upon initial results. The goal is to achieve the best possible TiO2 abundance maps from the ground as a precursor to lunar orbiter and robotic sample return missions, and to produce a better idea of the peak abundances of TiO2 for benefaction studies. These phases and the results are summarized

    Effectiveness of Two Water Conservation Policies: An Integrated Modeling Approach

    Get PDF
    Agriculture in the Texas High Plains depends entirely on the Ogallala Aquifer. Texas enacted water conservation legislation to address declining reserves in the aquifer. We developed an integrated regional water policy model that links a hydrology model with an economic optimization model to estimate policy impacts with respect to economic cost and water conservation. Testing the effectiveness of two policies, a groundwater extraction tax and extraction quotas, we observe that neither significantly inhibits groundwater use. Although both policies conserve similar amounts of groundwater, the regional cost of the tax policy to agriculture is more than the quota policy.integrated regional water policy model, Texas High Plains, water conservation policy, hydrology model, economic optimization model, Ogallala Aquifer, tax policy, quota policy, Agribusiness, Community/Rural/Urban Development, Food Security and Poverty, Land Economics/Use, Political Economy, Q30, Q31, Q38,

    Environmental Performance Index for the Forest

    Get PDF
    Comparative environmental performance indices for energy use, global warming potential (GWP), air, water, and solid waste emissions covering the stages of processing from the harvesting of wood and the extraction of non-renewable materials to the construction of a house using different materials are developed in other articles. Developing performance indices that compare renewable resources and their environmental impacts on the land base to the depletion of non-renewable resources is problematic. Materials that involve mining are inherently not renewable compared to forest resources, which are renewable over some rotation age of the forest. The environmental impacts on the forest are dynamic and are impacted by landscape changes with some related to the production of wood for markets. Forest ecology metrics are developed to show the impact of management alternatives based on changing stand structures. Forest diversity, measured by structure classes, is impacted by longer rotation and thinning alternatives as well as preservation and protection policies.Management alternatives can contribute to some restoration of pre-settlement conditions of forests and provides a benchmark from which to evaluate reduced stand structure diversity and loss of habitat. While a century of commercial management has reduced the diversity in the forest and in particular has increased the share of acres in both the stand initiation stage and the closed canopy or stem exclusion stage, the trend has already turned in response to demands for more forest acres under increased protection and preservation status. Increased thinning from more intensive management and policies to protect threatened species are both contributing to increased understory reinitiation and ultimately more complex old forest structures. Longer rotation management could add to this effect but at a substantial cost since the economics of long rotation management falls below acceptable levels for economic investments

    UAS Service Supplier Specification

    Get PDF
    Within the Unmanned Aircraft Systems (UAS) Traffic Management (UTM) system, the UAS Service Supplier (USS) is a key component. The USS serves several functions. At a high level, those include the following: Bridging communication between UAS Operators and Flight Information Management System (FIMS) Supporting planning of UAS operations Assisting strategic deconfliction of the UTM airspace Providing information support to UAS Operators during operations Helping UAS Operators meet their formal requirements This document provides the minimum set of requirements for a USS. In order to be recognized as a USS within UTM, successful demonstration of satisfying the requirements described herein will be a prerequisite. To ensure various desired qualities (security, fairness, availability, efficiency, maintainability, etc.), this specification relies on references to existing public specifications whenever possible

    Plyometric Exercises from a Knee Anterior Cruciate Ligament Prevention Program on the Rate of Isometric Torque Development and Vertical Jump Height

    Get PDF
    Purpose: Plyometric exercises are incorporated in anterior cruciate ligament injures of the knee (ACL) injury prevention programs that have effectively decreased risk factors for anterior cruciate ligament injures of the knee injuries, but the impact on the rate of isometric torque development of the musculature of the knee is unclear. The purpose of this study was to determine the effects of a 6-week plyometric program pulled from a commonly utilized anterior cruciate ligament injures of the knee injury prevention program on rate of isometric torque development (RTD) in healthy active females. Methods: College-aged participants were randomly split into two different groups (16-plyometric training and 15-control). Plyometric exercises included 180° jumps, bounding for distance, bounding in place, broad jump-stick, cone jumps, hop - hop stick, jump into bounding, jump - jump - jump vertical jump, mattress jumps, scissors jump, single-legged jumps for distance, squat jumps, step-jump up-down-vertical jump, tuck jumps, and wall jumps. Participants in the training group performed the exercises three times a week on alternating days, for 30-minute sessions. All participants performed a vertical jump measurement and completed maximum voluntary isometric contractions (MVICs) of ankle plantar flexion, knee extension, and knee flexion rate of torque development. Results: There was a main effect of session for plantar flexion rate of torque development time windows and vertical jump. The analysis revealed no significant differences for group by session interactions for any other rate of torque development measurement or the vertical jump. Conclusions: Plyometric exercises utilized from an anterior cruciate ligament injures of the knee injury prevention program did not change lower body isometric torque development or vertical jump height of active females. Since the plyometric training did not improve vertical jump, the training may not have been performed vigorous enough for the participants to cause a neuromuscular adaptation. Based on findings, 6-weeks of plyometric training from an isolated ACL injury prevention program should not be used to increase the vertical jump of healthy, active females

    Utility values for symptomatic non-severe hypoglycaemia elicited from persons with and without diabetes in Canada and the United Kingdom

    Get PDF
    <p>Abstract</p> <p>Objective</p> <p>To elicit societal and patient utilities associated with diabetic symptomatic non-severe hypoglycaemia for three health states: 1) rare (quarterly), 2) intermittent (monthly), 3) and frequent (weekly) hypoglycaemia episodes.</p> <p>Methods</p> <p>Using validated health states, time trade-off utilities were elicited from 51 Canadian respondents with diabetes, and 79 respondents in Canada and 75 respondents in the United Kingdom (UK) without diabetes.</p> <p>Results and discussion</p> <p>Each hypoglycaemic episode was associated with a reduction in utility and persons with diabetes consistently reported slightly higher utility values than respondents without diabetes. The utility for diabetes without hypoglycaemia ranged from 0.88 to 0.97, the mean utility for rare hypoglycaemic events (quarterly) ranged between 0.85 and 0.94. The utility for the intermittent state (monthly) ranged from 0.77 to 0.90 and from 0.66 to 0.0.83 for the frequent state (weekly). Differences were observed between respondents without diabetes in Canada and the UK. Using a multivariate linear OLS regression, the estimated utilities associated with a single hypoglycaemic event were -0.0033 and -0.0032 for respondents with diabetes and without diabetes, respectively.</p> <p>Conclusion</p> <p>Among respondents with and without diabetes, there was a demonstrable utility loss associated with hypoglycaemia. Considering a utility loss of 0.03 as a minimum clinically important difference for persons with diabetes, the evidence from this study indicates that as low as ten symptomatic non-severe hypoglycaemic episodes per year may be of clinical importance and that the importance increases with frequency of episodes. Integrating directly elicited utility values such as those reported here will improve the quality and applicability of economic evaluations of diabetes treatment.</p

    Introduction

    Get PDF

    Coherence in a transmon qubit with epitaxial tunnel junctions

    Full text link
    We developed transmon qubits based on epitaxial tunnel junctions and interdigitated capacitors. This multileveled qubit, patterned by use of all-optical lithography, is a step towards scalable qubits with a high integration density. The relaxation time T1 is .72-.86mu sec and the ensemble dephasing time T2 is slightly larger than T1. The dephasing time T2 (1.36mu sec) is nearly energy-relaxation-limited. Qubit spectroscopy yields weaker level splitting than observed in qubits with amorphous barriers in equivalent-size junctions. The qubit's inferred microwave loss closely matches the weighted losses of the individual elements (junction, wiring dielectric, and interdigitated capacitor), determined by independent resonator measurements
    • …
    corecore