Sharing the 620-790 MHz band allocated to terrestrial television with an audio-bandwidth social service satellite system

A study was carried out to identify the optimum uplink and downlink frequencies for audio-bandwidth channels for use by a satellite system distributing social services. The study considered functional-user-need models for five types of social services and identified a general baseline system that is appropriate for most of them. Technical aspects and costs of this system and of the frequency bands that it might use were reviewed, leading to the identification of the 620-790 MHz band as a perferred candidate for both uplink and downlink transmissions for nonmobile applications. The study also led to some ideas as to how to configure the satellite system

Variation in specificity of soil-borne pathogens from a plant's native range versus its nonnative range

Contains fulltext : 93607.pdf (publisher's version ) (Open Access

Theories of Valuation - Building Blocks for Conceptualizing Valuation between Practice and Structure

Phenomena of attributing value to objects, practices, and people, and of assessing their value have become a popular subject in sociological research. Classification, among other valuation practices, represents a central topic in these studies. Thus, the sociology of valuation is emerging as a new field that, however, lacks common ground in theorizing about its subject even though preoccupation with valuation has a long-standing history in sociology. Authors such as Durkheim, Simmel, and Dewey have interpreted valuation as more than a specific localizable phenomenon, in that valuation is a constitutive element of the fundament of the social. Discussing classical approaches to valuation and relating them to current sociological work, we identify key concepts within different theoretical approaches that need to be taken into account when theorizing valuation. We suggest five building blocks - valuation practices, value structures, valuation infrastructure, valuation situations, and reflexivity of valuation - theories of valuation need to consider for coming to terms with the multi-faceted empirical studies in the sociology of valuation

Multi-level multi-criteria analysis of alternative fuels for waste collection vehicles in the United States

Historically, the U.S. waste collection fleet was dominated by diesel-fueled waste collection vehicles (WCVs); the growing need for sustainable waste collection has urged decision makers to incorporate economically efficient alternative fuels, while mitigating environmental impacts. The pros and cons of alternative fuels complicate the decisions making process, calling for a comprehensive study that assesses the multiple factors involved. Multi-criteria decision analysis (MCDA) methods allow decision makers to select the best alternatives with respect to selection criteria. In this study, two MCDA methods, Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and Simple Additive Weighting (SAW), were used to rank fuel alternatives for the U.S. waste collection industry with respect to a multi-level environmental and financial decision matrix. The environmental criteria consisted of life-cycle emissions, tail-pipe emissions, water footprint (WFP), and power density, while the financial criteria comprised of vehicle cost, fuel price, fuel price stability, and fueling station availability. The overall analysis showed that conventional diesel is still the best option, followed by hydraulic-hybrid WCVs, landfill gas (LFG) sourced natural gas, fossil natural gas, and biodiesel. The elimination of the WFP and power density criteria from the environmental criteria ranked biodiesel 100 (BD100) as an environmentally better alternative compared to other fossil fuels (diesel and natural gas). This result showed that considering the WFP and power density as environmental criteria can make a difference in the decision process. The elimination of the fueling station and fuel price stability criteria from the decision matrix ranked fossil natural gas second after LFG-sourced natural gas. This scenario was found to represent the status quo of the waste collection industry. A sensitivity analysis for the status quo scenario showed the overall ranking of diesel and fossil natural gas to be more sensitive to changing fuel prices as compared to other alternatives

NASA's SDR Standard: Space Telecommunications Radio System

A software defined radio (SDR) architecture used in space-based platforms proposes to standardize certain aspects of radio development such as interface definitions, functional control and execution, and application software and firmware development. NASA has charted a team to develop an open software defined radio hardware and software architecture to support NASA missions and determine the viability of an Agency-wide Standard. A draft concept of the proposed standard has been released and discussed among organizations in the SDR community. Appropriate leveraging of the JTRS SCA, OMG s SWRadio Architecture and other aspects are considered. A standard radio architecture offers potential value by employing common waveform software instantiation, operation, testing and software maintenance. While software defined radios offer greater flexibility, they also poses challenges to the radio development for the space environment in terms of size, mass and power consumption and available technology. An SDR architecture for space must recognize and address the constraints of space flight hardware, and systems along with flight heritage and culture. NASA is actively participating in the development of technology and standards related to software defined radios. As NASA considers a standard radio architecture for space communications, input and coordination from government agencies, the industry, academia, and standards bodies is key to a successful architecture. The unique aspects of space require thorough investigation of relevant terrestrial technologies properly adapted to space. The talk will describe NASA s current effort to investigate SDR applications to space missions and a brief overview of a candidate architecture under consideration for space based platforms

An environmental-economic assessment of residential curbside collection programs in Central Florida

© 2016 Elsevier Ltd.Inefficient collection and scheduling procedures negatively affect residential curbside collection (RCC) efficiency, greenhouse gas (GHG) emissions, and cost. As Florida aims to achieve a 75% recycling goal by 2020, municipalities have switched to single-stream recycling to improve recycling efficiency. Waste diversion and increased collection cost have forced some municipalities to reduce garbage collection frequency. The goal of this study was to explore the trade-offs between environmental and economic factors of RCC systems in Florida by evaluating the RCC system design of 25 different Central Florida communities. These communities were grouped into four sets based on their RCC garbage, yard waste, and recyclables collection design, i.e., frequency of collection and use of dual-stream (DS) or single-stream (SS) recyclables collection system. For the 25 communities studied, it was observed that RCC programs that used SS recyclables collection system recycled approximately 15-35%, by weight of the waste steam, compared to 5-20% for programs that used DS. The GHG emissions associated with collection programs were estimated to be between 36 and 51 kg CO2eq per metric ton of total household waste (garbage and recyclables), depending on the garbage collection frequency, recyclables collection system (DS or SS), and recyclables compaction. When recyclables offsets were considered, the GHG emissions associated with programs using SS were estimated between -760 and -560, compared to between -270 and -210 kg CO2eq per metric ton of total waste for DS programs. These data suggest that RCC system design can significantly impact recyclables generation rate and efficiency, and consequently determine environmental and economic impacts of collection systems. Recycling participation rate was found to have a significant impact on the environmental and financial performance of RCC programs. Collection emissions were insignificant compared to the benefits of recycling. SS collection of recyclables provided cost benefits compared to DS, mainly due to faster collection time

(RSS)-[N-Hydroxyethyloxy]-hexafluoroVal–MeLeu–Ala tert-butyl ester

The title compound [systematic name: (2S,5S,8R)-tert-butyl 8-(1,1,1,3,3,3-hexafluoropropan-2-yl)-12-hydroxy-5-isobutyl-2,6-dimethyl-4,7-dioxo-10-oxa-3,6,9-triazadodecanoate], C21H36F6N3O6, is a tripeptide crystallizing in the chiral ortho­rhom­bic spacegroup P212121. The absolute configuration (R) of the chiral center in the hexa­fluoro­valine unit is based on the known stereochemistry of MeLeu and Ala (SS). The N-hydroxy­ethyl­oxy substituent of hexa­fluoro­valine is positionally disordered [occupancy ratio 0.543 (9):0.457 (9)]. In the solid state structure there are N—H⋯F and N—H⋯O intra­molecular hydrogen bonds supporting the coiled structure of this tripeptide with the three hydro­phobic substituents on the outside