12,898 research outputs found

    Distributed lag models for hydrological data

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    The distributed lag model (DLM), used most prominently in air pollution studies, finds application wherever the effect of a covariate is delayed and distributed through time. We explore the use of modified formulations of DLMs to provide flexible varying-coeficient models with smoothness constraints, applicable in any setting in which lagged covariates are regressed on a time-dependent response. The models are applied to simulated flow and rainfall data and to flow data from a Scottish mountain river, with particular emphasis on approximating the relationship between environmental covariates and flow regimes in order to detect the influence of unobserved processes. It was found that under certain rainfall conditions some of the variability in the influence of rainfall on flow arises through a complex interaction between antecedent ground wetness and the time-delay in rainfall. The models are able to identify subtle changes in rainfall response, particularly in the location of peak influence in the lag structure and offer a computationally attractive approach for fitting DLMs

    Bridging the Climate Information Gap: A Framework for Engaging Knowledge Brokers and Decision Makers in State Climate Assessments

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    Large-scale analyses like the National Climate Assessment (NCA) contain a wealth of information critical to national and regional responses to climate change but tend to be insufficiently detailed for action at state or local levels. Many states now engage in assessment processes to meet information needs for local authorities. The goals of state climate assessments (SCAs) should be to provide relevant, actionable information to state and local authorities, and to generate primary sources, build networks and inform stakeholders. To communicate local climate impacts to decision makers, SCAs should express credibility, salience and legitimacy. They can provide information (e.g., case studies, data sets) and connect stakeholders to the NCA and its process. Based on our experience in the Vermont Climate Assessment (VCA), we present a framework to engage decision makers in SCAs using a fluid network of scientific experts and knowledge brokers to conduct subject area prioritization, data analysis and writing. The VCA addressed economic, environmental and social impacts of climate change at local scales to increase resiliency and manage risk. Knowledge brokers communicated VCA findings through their own stakeholder networks. We include a qualitative impact evaluation, and believe our framework for interaction among scientists, knowledge brokers and stakeholders to be an effective structure for SCAs and a transformative experience for students

    The Complexity of Nash Equilibria in Simple Stochastic Multiplayer Games

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    We analyse the computational complexity of finding Nash equilibria in simple stochastic multiplayer games. We show that restricting the search space to equilibria whose payoffs fall into a certain interval may lead to undecidability. In particular, we prove that the following problem is undecidable: Given a game G, does there exist a pure-strategy Nash equilibrium of G where player 0 wins with probability 1. Moreover, this problem remains undecidable if it is restricted to strategies with (unbounded) finite memory. However, if mixed strategies are allowed, decidability remains an open problem. One way to obtain a provably decidable variant of the problem is restricting the strategies to be positional or stationary. For the complexity of these two problems, we obtain a common lower bound of NP and upper bounds of NP and PSPACE respectively.Comment: 23 pages; revised versio

    National Register of Historic Places Eligibility Testing of Site 41SM385 Within TxDOT\u27s Tyler District, Smith County, Texas

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    PBS&J, an Atkins company, was contracted by the North East Texas Regional Mobility Authority to conduct National Register of Historic Places eligibility testing of site 41SM385, a prehistoric campsite on a small rise above the floodplain of Indian Creek in western Smith County, Texas. Testing investigations were conducted during March and September 2009. The site was subjected to a systematic program of shovel testing, mechanical trenching, and hand excavation in an effort to identify cultural features or living surfaces and optimize recovery of diagnostic faunal, floral, and artifactual remains. The recovered cultural artifacts indicate that site 41SM385 represents a probable Woodland and Caddo‐aged occupation on a small rise on the creek floodplain. The Woodland component is based on recovered small Gary and Kent projectile points characteristic of Woodland culture of the region. The Caddo component is based on ceramic sherds of probable Early or Middle Caddo origin identified at the site. Radiocarbon dating of four ceramic sherds supports these assessments with three sherds dating to the Early to Middle Caddo periods and one sherd dating to the Woodland period. The lack of identified cultural features suggests that the Woodland component probably represents a series of ephemeral usages of the location, probably as short‐term campsites. The Caddo‐aged artifacts at the site probably represent a series of ephemeral usage of the location, either as a resource procurement locus ancillary to nearby site 41SM404 or as a short‐term campsite. The testing program failed to locate living surfaces or cultural features containing in situ artifactual or organic remains preserved on the site. The absence of cultural features and the paucity of lithic tools or ceramic remains make more‐meaningful functional interpretation infeasible. For this reason, the site lacks the data resources that would warrant National Register of Historic Places isting or designation as a State Archeological Landmark. No further work is recommended

    Response to Kamath et al 'A syncretic approach can yield dividends'

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    We welcome the response from Kamath et al. and their insight into the issues and culture within medicine in India, and their thoughts about how to address these issues. We also agree that a drama-based approach is not sufficient on its own to deal with entrenched power issues which affect students adversely. As we have indicated, we believe “a multipronged approach is needed to generate systemic change.” These authors similarly advocate that student mistreatment be dealt with “in a comprehensive manner” including a ‘grievance redressal system’ and other measures to withhold accreditation where there are issues of abuse of power. Nevertheless, we note that Kamath et al. have responded positively to our approach—as a part of that mix—and it would be of great interest to see whether drama-based workshops could support medical students developing embodied acting skills in their institution and whether they may have similar transformative effects. We’d like to refer the authors to an excellent Medical Humanities paper we referenced that outlined drama-based activities in medical education in India: Gupta S, Singh S. Confluence: understanding medical humanities through street theatre. Medical Humanities. 2011;37(2):127-128. Despite the above article, the authors note that medical education in India has not embraced the medical humanities. We would draw a distinction within the medical humanities between activities which are primarily studious (reading literature, studying medical history) and workshops that are based on participative and embodied activity. Our experience has indicated the effectiveness of drama-based workshops in addressing both the cognitive and emotive aspects of harmful practices and we believe that it is the embodied nature of acting skills workshops that is transformative

    Methods for identifying low emissions development options for agriculture

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    Low emissions development strategies (LEDS) are national economic and social development plans that promote sustainable development while reducing GHG emissions. While LEDS programs have helped to mainstream economy-wide planning for low emissions, planning for low emissions agriculture has remained nascent. Low-emissions development (LED) in agriculture acknowledges that the primary purpose of agriculture is to produce food and other goods for human needs, and that climate change mitigation is a secondary goal that should not compromise production. This paper describes a research process and protocol to identify high potential LED options in agriculture at the United States Agency for International Development (USAID). The case study illustrates the steps for the identification and prioritization of LED options including: idea generation, concept development, and evidence building. Each stage is designed to gather and analyze data that specifically enable managers and stakeholders to make informed evaluations. The method gathers not only emission and mitigation information but also food security and income generation data, lending process legitimacy to the research. The incorporation of institutional factors and local contextual systems in the LED concept development stage improves the output credibility and salience. In the final process phase, stakeholders are given an active role in determining the criteria for prioritization and building evidence. The LED option identification and prioritization process illustrates how careful evidence-building can increase the credibility and salience of outputs and legitimacy of the overall results

    Building on the Past - Looking to the Future. Part 2: A Focus on Expanding Horizons

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    The history of space endeavors stretches far from the first liquid-fueled rocket created by the father of modern rocketry, Robert Goddard, in 1926 and will certainly extend far beyond the construction of the International Space Station (ISS) scheduled to be complete with the addition of the Permanent Multipurpose Module on STS-133/ULF5. National Aeronautics and Space Administration (NASA) and the ISS International Partners (IPs) will be the unrelenting venue used to satisfy the curiosities of man as we seek an understanding of space through various experiments (also referred to as payloads) conducted in microgravity. The NASA Payload Safety Review Panel (PSRP) continues to serve as the lead for the review and assessment of payload hardware to assure facility and crew safety. This is the second in a series of papers and presentations that illustrate challenges and lessons learned in the areas of communication, safety requirements, and processes which have been vital to the PSRP

    Experimental Observation of Rainbow Scattering by a Coated Cylinder: Twin Primary Rainbows and Thin-Film Interference

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    We experimentally examine the primary rainbow created by the illumination of a coated cylinder. We present a simple technique for varying the coating thickness over a wide range of values, and we see evidence for two different scattering regimes. In one, where the coating thickness is large, twin rainbows are produced. In the second, where the coating is thin enough to act as a thin film, a single rainbow is produced whose intensity varies periodically as the coating thickness varies. We find good agreement with previous theoretical predictions. (C) 2001 Optical Society of America

    Building on the Past - Looking to the Future: A Focus on Payload Safety

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    The history of the space industry stretches far and above lunar landings to the construction of the International Space Station. For years, humans have sought to understand the nature of the universe. As society grows in knowledge and curiosity of space, the focus of maintaining the safety of the crew and vehicle habitability is of utmost importance to the National Aeronautics and Space Administration (NASA) community. Through the years, Payload Safety has developed not only as a Panel, but also as part of the NASA community, striving to enhance the efficiency and understanding of how business should be conducted as more International Partners become involved. This is the first in a series of papers and presentations in what is hoped to be an annual update that provides continuous challenges and lessons learned in the areas of communication, safety requirements and processes and other areas which have been vital to the Payload Safety Review Panel (PSRP)
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