11,271 research outputs found
Communications platform payload definition study, executive summary
Large geostationary communications platforms have been investigated in a number of studies since 1974 as a possible means to more effectively utilize the geostationary orbital arc and electromagnetic spectrum and to reduce overall satellite communications system costs. This NASA Lewis sponsored study addresses the commercial feasibility of various communications platform payload concepts circa 1998. It defines promising payload concepts, estimates recurring costs and identifies critical technologies needed to permit eventual commercialization. Ten communications service aggregation scenarios describing potential groupings of services were developed for a range of conditions. Payload concepts were defined for four of these scenarios: (1) Land Mobile Satellite Service (LMSS), meet 100% of CONUS plus Canada demand with a single platform; (2) Fixed Satellite Service (FSS) (Trunking + Customer Premises Service (CPS), meet 20% of CONUS demands; (3) FSS (Trunking + video distribution), 10 to 13% of CONUS demand; and (4) FSS (20% of demand) + Inter Satellite Links (ISL) + TDRSS/TDAS Data Distribution
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Double-duty actions for ending malnutrition within a decade
Malnutrition has many forms. Undernutrition can see children dangerously thin for their height (wasting), or their growth permanently impeded (stunting). Inadequate intake of key nutrients may weaken immune systems, impair brain development, and worsen the risk of conditions such as anaemia and blindness. Diets rich in calories well beyond the body's metabolic needs drive the burden of overweight and obesity, while excess dietary fat, sugar, and salt can increase the risks of non-communicable diseases (NCDs)
A simple assessment of housing retrofit policies for the UK: what should succeed the energy company obligation?
Despite the need for large-scale retrofit of UK housing to meet emissions reduction targets, progress to date has been slow and domestic energy efficiency policies have struggled to accelerate housing retrofit processes. There is a need for housing retrofit policies that overcome key barriers within the retrofit sector while maintaining economic viability for customers, funding organizations, and effectively addressing UK emission reductions and fuel poverty targets. In this study, we use a simple assessment framework to assess three policies (the Variable Council Tax, the Variable Stamp Duty Land Tax, and Green Mortgage) proposed to replace the UKâs current major domestic retrofit programme known as the Energy Company Obligation (ECO). We show that the Variable Council Tax and Green Mortgage proposals have the greatest potential for overcoming the main barriers to retrofit policies while maintaining economic viability and contributing to high-level UK targets. We also show that, while none of the assessed schemes are capable of overcoming all retrofit barriers on their own, a mix of all three policies could address most barriers and provide key benefits such as wide coverage of property markets, operation on existing financial infrastructures, and application of a âcarrot-and-stickâ approach to incentivize retrofit. Lastly, we indicate that the specific support and protection of fuel-poor households cannot be achieved by a mix of these policies and a complementary scheme focused on fuel-poor households is required
Searches for New Quarks and Leptons Produced in Z-Boson Decay
We have searched for events with new-particle topologies in 390 hadronic Z decays with the Mark II detector at the SLAC Linear Collider. We place 95%-confidence-level lower limits of 40.7 GeV/c^2 for the top-quark mass, 42.0 GeV/c^2 for the mass of a fourth-generation charge - 1/3 quark, and 41.3 GeV/c^2 for the mass of an unstable Dirac neutral lepton
Measurement of Z Decays into Lepton Pairs
We present measurements by the Mark II experiment of the ratios of the leptonic partial widths of the Z boson to the hadronic partial width. The results are Î_(ee)/Î_(had)=0.037_(-0.012^()+0.016),Î_(””)/Î_(had)=0.053-_(0.015)^(+0.020), and Î_(ÏÏ)/Î_(had)=0.066_(-0.017)^(+0.021), in good agreement with the standard-model prediction of 0.048. From the average leptonic width result, Î_(ll)/Î_(had)=0.053_(-0.009)^(+0.010), we derive Î_(had)=1.56_(-0.24)^(+0.28) GeV. We find for the vector coupling constants of the tau and muon v_Ï^2=0.31±0.31_(-0.30)^(+0.43) and v_ÎŒ^2=0.05±0.30_(-0.23)^(+0.34)
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How Is COVID-19 Shaping Familiesâ Relationships With Food and the Food Environment in England? A Qualitative Research Protocol
Rates of childhood overweight and obesity continue to rise in England, along with a growing gap in obesity prevalence between children in the most and least deprived areas. To address child obesity, the UK government is increasingly considering how to intervene in the (food) environments that shape peopleâs purchases, rather than focusing solely on individual health behaviors. With the COVID-19 pandemic and subsequent lockdowns having rapidly reconfigured life in the UK, it is important to understand how these changes may have impacted food practices and engagement with food environments. This remote, longitudinal qualitative study seeks to explore how the COVID-19 pandemic and its impacts are shaping families relationships with the food and the food environment. A sample of 60â80 parents/carers of school or nursery-aged children will be recruited from across three case study sites in England to take part in semi-structured interviews and set of flexible creative activities at three time points over the course of a year. Findings will provide practical policy insights for Englandâs obesity prevention strategy as well as methodological insights in terms of conducting research into lived experience remotely
Distribution and abundance of fish and crayfish in a Waikato stream in relation to basin area
The aim of this study was to relate the longitudinal distribution of fish and crayfish to increasing basin area and physical site characteristics in the Mangaotama Stream, Waikato region, North Island, New Zealand. Fish and crayfish were captured with two-pass removal electroshocking at 11 sites located in hill-country with pasture, native forest, and mixed land uses within the 21.6 km2 basin. Number of fish species and lineal biomass of fish increased with increasing basin area, but barriers to upstream fish migration also influenced fish distribution; only climbing and non-migratory species were present above a series of small waterfalls. Fish biomass increased in direct proportion to stream width, suggesting that fish used much of the available channel, and stream width was closely related to basin area. Conversely, the abundance of crayfish was related to the amount of edge habitat, and therefore crayfish did not increase in abundance as basin area increased. Densities of all fish species combined ranged from 17 to 459 fish 100 m-2, and biomass ranged from 14 to 206 g m-2. Eels dominated the fish assemblages, comprising 85-100% of the total biomass; longfinned eels the majority of the biomass at most sites. Despite the open access of the lower sites to introduced brown trout, native species dominated all the fish communities sampled
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