4,789 research outputs found

    Translation planes of order q3 which admits SL(2, q)

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    Operational and Technical Updates to the Object Reentry Survival Analysis Tool

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    The Object Reentry Survival Analysis Tool (ORSAT) has been used in the NASA Orbital Debris Program Office for over 25 years to estimate risk due to uncontrolled reentry of spacecraft and rocket bodies. Development over the last 3 years has included: a major change to the treatment of carbon fiber- and glass fiber-reinforced plastics (CFRP and GFRP, respectively); an updated atmospheric model; a new model for computing casualty area around an impacting debris object; and a newly-implemented scheme to determine the breakup altitude of a reentry object. Software also was written to automatically perform parameter sweeps in ORSAT to allow for uncertainty quantification and sensitivity analysis for components with borderline demisability. These updates have improved the speed and fidelity of the reentry analysis performed using ORSAT, and have allowed for improved engineering understanding by estimating the uncertainty for each components survivability. A statistical model for initial conditions captures the latitude bias in population density, a large improvement over the previous inclination-based latitude-averaged models. A sample spacecraft has been analyzed with standard techniques using ORSAT 6.2.1 and again using all the updated models; we will demonstrate the variation in the total debris casualty area and overall expectation of casualty

    Trust in Private and Common Property Experiments

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    We report the results from a series of experiments designed to investigate behavior in two settings that are frequently posited in the policy literature as generating different outcomes: private property and common property. The experimental settings closely parallel earlier experimental studies of the investment or trust game. The primary research question relates to the effect of the initial allocation of property rights on the level of trust that subjects will extend to others with whom they are linked. We find that assigning the initial endowments as common property of each of N pairs of a first mover and second mover leads to marginally greater cooperation or trust than when the initial endowments are fully owned by the two individual movers as their, respective, private property. Subjectsâ?? decisions are also shown to be correlated with attitudes toward trust and fairness that are measured in post-experiment questionnaires.

    Construction of silicon nanocolumns with the scanning tunneling microscope

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    Voltage pulses to a scanning tunneling microscope (STM) are used to construct silicon columns of 30–100 Å diameter and up to 200 Å height on a silicon surface and on the end of a tungsten probe. These nanocolumns have excellent conductivity and longevity, and they provide an exceptional new ability to measure the shapes of nanostructures with a STM. This construction methodology and these slender yet robust columns provide a basis for nanoscale physics, lithography, and technology

    Persuading consumers to reduce their consumption of electricity in the home

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    Previous work has identified that providing real time feedback or interventions to consumers can persuade consumers to change behaviour and reduce domestic electricity consumption. However, little work has investigated what exactly those feedback mechanisms should be. Most past work is based on an in-home display unit, possibly complemented by lower tariffs and delayed use of non-essential home appliances such as washing machines. In this paper we focus on four methods for real time feedback on domestic energy use, developed to gauge the impact on energy consumption in homes. Their feasibility had been tested using an experimental setup of 24 households collecting minute-by-minute electricity consumption data readings over a period of 18 months. Initial results are mixed, and point to the difficulties of sustaining a reduction in energy consumption, i.e. persuading consumers to change their behaviour. Some of the methods we used exploit small group social dynamics whereby people want to conform to social norms within groups they identify with. It may be that a variety of feedback mechanisms and interventions are needed in order to sustain user interest

    Advantages of a Polycentric Approach to Climate Change Policy

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    Lack of progress in global climate negotiations has led scholars to reconsider polycentric approaches to climate policy. Several examples of subglobal mechanisms to reduce greenhouse-gas emissions have been touted, but it remains unclear why they might achieve better climate outcomes than global negotiations alone. Decades of work conducted by researchers associated with the Vincent and Elinor Ostrom Workshop in Political Theory and Policy Analysis at Indiana University have emphasized two chief advantages of polycentric approaches over monocentric ones: they provide more opportunities for experimentation and learning to improve policies over time, and they increase communications and interactions — formal and informal, bilateral and multilateral — among parties to help build the mutual trust needed for increased cooperation. A wealth of theoretical, empirical and experimental evidence supports the polycentric approach

    New Wilson’s Phalarope Nesting Record from the Central Platte River Valley, Mormon Island, Hall County, Nebraska

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    The southeastern portion of the Wilson’s Phalarope’s (Phalaropus tricolor) breeding range encompasses parts of Nebraska (Colwell and Jehl 1994), including the Sandhills and northern Panhandle (Silcock and Jorgensen 2018). Additionally, there have been a number of breeding records from southcentral and southeastern Nebraska within the Rainwater Basin ecoregion since the mid-1990s (Mollhoff 2016, Silcock and Jorgensen 2018). However, there is very little evidence of regular breeding activity in the nearby Central Platte River Valley (CPRV), which spans from Chapman west to Overton, Nebraska, and is considered a globally important area for waterbirds (Johnsgard and Brown 2013, Silcock and Jorgensen 2018). Sutton and Arcilla (2018) documented two juvenile Wilson’s Phalaropes with two adults on 28 June 2017, confirming successful breeding in the CPRV on Mormon Island, Hall County, Nebraska. However, Sutton and Arcilla (2018) did not document an active nest and therefore lack a detailed description of the nesting habitat used by Wilson’s Phalaropes in this unique ecoregion. On 6 June 2019 we found a Wilson’s Phalarope nest while walking between avian point count stations on Mormon Island, 4.7 km northwest of Doniphan and 14.4 km southwest of Grand Island, Nebraska, on land owned and managed for the benefit of migratory birds by the Crane Trust (https://cranetrust.org/). The landscape is managed with rotational grazing and prescribed fire to simulate natural disturbance regimes (Fuhlendorf et al. 2009). Mormon Island contains the largest contiguous tract of wet meadow remaining in the CPRV (Currier and Henszey 1996, Brei and Bishop 2008). Mormon Island consists of about 1075 hectares (ha) or 2,656 acres (ac) of primarily relict and restored wet meadow and lowland tallgrass prairie habitat, and exists within a complex of 2,425 ha (5,992 ac) of land protected for conservation purposes along a 13 km (~8 mi.) stretch of the Platte River. The nest was found when an adult male Wilson’s Phalarope flushed directly off the nest from the ground at a distance of approximately 3 meters (m) from approaching observers

    Climate change adaptation in European river basins

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    This paper contains an assessment and standardized comparative analysis of the current water management regimes in four case-studies in three European river basins: the Hungarian part of the Upper Tisza, the Ukrainian part of the Upper Tisza (also called Zacarpathian Tisza), Alentejo Region (including the Alqueva Reservoir) in the Lower Guadiana in Portugal, and Rivierenland in the Netherlands. The analysis comprises several regime elements considered to be important in adaptive and integrated water management: agency, awareness raising and education, type of governance and cooperation structures, information management and—exchange, policy development and—implementation, risk management, and finances and cost recovery. This comparative analysis has an explorative character intended to identify general patterns in adaptive and integrated water management and to determine its role in coping with the impacts of climate change on floods and droughts. The results show that there is a strong interdependence of the elements within a water management regime, and as such this interdependence is a stabilizing factor in current management regimes. For example, this research provides evidence that a lack of joint/participative knowledge is an important obstacle for cooperation, or vice versa. We argue that there is a two-way relationship between information management and collaboration. Moreover, this research suggests that bottom-up governance is not a straightforward solution to water management problems in large-scale, complex, multiple-use systems, such as river basins. Instead, all the regimes being analyzed are in a process of finding a balance between bottom-up and top–down governance. Finally, this research shows that in a basin where one type of extreme is dominant—like droughts in the Alentejo (Portugal) and floods in Rivierenland (Netherlands)—the potential impacts of other extremes are somehow ignored or not perceived with the urgency they might deserv
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