1,598 research outputs found
Personal BioBlitz: A New Way to Encourage Biodiversity Discovery and Knowledge in K-99 Education and Outreach
No full textBroad and detailed knowledge about common species in everyday life has decreased among the public. Even biology researchers may be largely unaware of our everyday biodiversity. To counter such 'species blindness' and create long-term excitement and learning about the biodiversity we see every day, we arranged 76-day BioBlitzes at Rutgers University (New Jersey, USA) in 2014 and 2015 where participants identified and listed all species they discovered. The result was 7270/11748 observations from 30/78 participants and 7/13 countries, including 3458/3057 unique taxa, 91%/99.9% identified to species and 80%/54% listed only by one person (2014/2015). Observations of organismal groups did not strongly correspond to number of estimated species worldwide, but appeared to be related to perceived charisma, body size, and organism mobility. Participants reported increased ability to 'see' species and to identify new groups, learning new tools of species identification and strongly increasing their biodiversity knowledge and eagerness to learn more.Peer reviewe
Essays on coordination and financial markets
No full textThis dissertation is concerned with microeconomic models of equilibrium pricing in financial markets of varying organizational scope. The first two chapters are based on game-theoretic models characterized by a coordination problem. I begin at the industry level in Chapter 2 where I solve the chicken-or-the-egg problem of platform pricing. I show that the elasticity of demand is greater for the more valued side and hence a monopolist will charge that side a lower price. These results have implications on how exchanges admit traders and apply to more general two-sided markets. My findings are supported by experimental tests. Chapter 3 examines regulatory efficacy in manipulating a currency market with a peg. I solve for equilibrium speculator conduct and central bank intervention policy where the speculator population is discrete. Sudden equilibrium price collapses are related explicitly to fundamentals. The main findings are again supported by experimental tests. In the final chapter, I study a market where strategic behavior is set aside and market participants are instead assumed to be perfect delta hedgers who immediately exploit arbitrage opportunities. I numerically estimate the equilibrium price of an exotic option in such a market.Ph. D.Includes bibliographical referencesIncludes vitaby Nicholas B. Galuni
External interventions and the duration of civil wars
No full textThe authors combine an empirical model of external intervention, with a theoretical model of civil war duration. Their empirical model of intervention allows them to analyze civil war duration, using"expected"rather than"actual"external intervention as an explanatory variable in the duration model. Unlike previous studies, they find that external intervention is positively associated with the duration of civil war. They distinguish partial third-party interventions that extend the length of war, from multilateral"peace"operations, which have a mandate to restore peace without taking sides - and which typically take place at war's end, or at least when both sides have agreed to a cease-fire. In a future paper, the authors will examine whether partial third-party interventions - whatever their effect on a war's duration - increase the risk of war's recurrence. If that proves true, then even if interventions reduce the length of civil war, they may do so at the cost of further destabilizing the political system, and sowing the seeds of future rebellion.Children and Youth,Peace&Peacekeeping,Post Conflict Reconstruction,Post Conflict Reconstruction,International Affairs,Post Conflict Reconstruction,Social Conflict and Violence,Peace&Peacekeeping,Post Conflict Reconstruction,International Affairs
Author(s): Ezra Brown and Nicholas Loehr Source
No full textJSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. . Why is PSL(2, 7) = GL(3, 2)? Mathematical Association of America Ezra Brown and Nicholas Loehr 1. INTRODUCTION. The groups of invertible matrices over finite fields are among the first groups we meet in a beginning course in modern algebra. Eventually, we find out about simple groups and that the unique simple group of order 168 has two representations as a group of matrices. And this is where we learn that the group of 2x2 unimodular matrices over a seven-element field, with / and -/ identified, is isomorphic to the group of invertible 3x3 matrices over a 2-element field. In short, it is a fact that PSL(2, 7) = GL(3, 2). Many of us are surprised by this fact: why should a group of 2 x 2 matrices with mod-7 integer entries be isomorphic to a group of 3 x 3 binary matrices? There are a number of proofs of this remarkable theorem. Dickson [1, p. 303] gives a proof based on his general theorem giving uniform sets of generators and relations for the family of groups SL(2, q), where q is any prime power. One checks that the relations appearing in Dickson's presentation of PSL(2, 7) are satisfied by certain generators of GL(3, 2), implying that these groups have the same presentations and are therefore isomorphic. Dummit and Foote [2, show that every simple group of order 168 is necessarily isomorphic to the automorphism group Aut(.F) of the Fano plane T. They then show that Aut(^) = GL(3, 2) and that PSL(2, 7) is a simple group of order 168; the isomorphism theorem follows. Rotman gives the result as an exercise [5, Exercise 9.26, p. 281]. A hint is to begin with a simple group G of order 168 and use the seven conjugates of a Sylow 2-subgroup P of G to construct a sevenpoint projective plane; the proof is similar to Dummit and Foote's proof. Jeurissen [4] proves the result by showing that both PSL(2, 7) and GL(3, 2) are subgroups of index 2 of the automorphism group of a Coxeter graph. Elkies The aim of this paper is to give a proof that PSL(2, 7) = GL(3, 2) that is elementary in the sense that it uses neither simplicity, nor projective geometry, nor block designs. We will not prove the fact that any two simple groups of order 168 are isomorphic, nor will we use this fact in our proof. What makes our proof work is that: (a) we can identify GL(3, 2) with the set of invertible F2-linear transformations on the finite field with eight elements; (b) 7 = 23 -1; (c) the nonzero squares mod 7 are precisely the powers of 2 mod 7; (d) squaring mod 2 is additive (the Freshman's Dream); and (e) the mapping k h+ -i/k mod 7 translates to a bit-switch mod 2 -which is linear. We begin by giving functional descriptions for both groups, determining their sizes
Curbside buses and the transformation of the intercity bus industry
No full textSince the late 1990s, a new type of intercity transportation has transformed travel in many American cities. This new travel option has not come from revolutionary technological innovation, large-scale infrastructure investment, or long-term planning efforts. Rather, the new travel option is the intercity bus, a mode that had been in decline for decades. After roughly fifty years of steady decline in ridership, intercity buses are suddenly the fastest growing intercity mode in the United States. This growth is due to curbside intercity buses, which pick up and drop off passengers on city street corners rather than in bus terminals. This seemingly small change in operations is at the heart of the dramatic growth in intercity bus travel. On the Northeast Corridor alone, intercity bus travel has more than doubled between 1997 and 2007 from three and a half million to over seven million trips. This research looks beyond the growth in ridership to unpack what these changes mean for the passengers on these buses, for the public at large, for competing intercity providers, and for regulators and local transportation planners. This dissertation poses three broad research questions. First, how and why do passengers choose to take curbside buses? Second, who uses curbside buses and how are these buses influencing their travel behavior? Third, how are curbside buses changing both the intercity bus industry and how have city planners responded to the problems associated with an influx of curbside intercity buses on city streets?Ph. D.Includes bibliographical referencesby Nicholas Klei
Reducing Emergency Department Visits for Acute Gastrointestinal Illnesses in North Carolina (USA) by Extending Community Water Service
No full textBACKGROUND: Previous analyses have suggested that unregulated private drinking water wells carry a higher risk of exposure to microbial contamination than regulated community water systems. In North Carolina, ~35% of the state's population relies on private wells, but the health impact associated with widespread reliance on such unregulated drinking water sources is unknown.
OBJECTIVES: We estimated the total number of emergency department visits for acute gastrointestinal illness (AGI) attributable to microbial contamination in private wells in North Carolina per year, the costs of those visits, and the potential health benefits of extending regulated water service to households currently relying on private wells for their drinking water.
METHODS: We developed a population intervention model using 2007-2013 data from all 122 North Carolina emergency departments along with microbial contamination data for all 2,120 community water systems and for 16,138 private well water samples collected since 2008.
RESULTS: An estimated 29,400 (95% CI: 26,600, 32,200) emergency department visits per year for acute gastrointestinal illness were attributable to microbial contamination in drinking water, constituting approximately 7.3% (95% CI: 6.6, 7.9%) of all AGI-related visits. Of these attributable cases, 99% (29,200; 95% CI: 26,500, 31,900) were associated with private well contamination. The estimated statewide annual cost of emergency department visits attributable to microbiological contamination of drinking water is 40.2 million USD (95% CI: 2.58 million USD, 193 million USD), of which 39.9 million USD (95% CI: 2.56 million USD, 192 million USD) is estimated to arise from private well contamination. An estimated 2,920 (95% CI: 2,650, 3,190) annual emergency department visits could be prevented by extending community water service to 10% of the population currently relying on private wells.
CONCLUSIONS: This research provides new evidence that extending regulated community water service to populations currently relying on private wells may decrease the population burden of acute gastrointestinal illness.
CITATION: DeFelice NB, Johnston JE, Gibson JM. 2016. Reducing emergency department visits for acute gastrointestinal illnesses in North Carolina (USA) by extending community water service. Environ Health Perspect 124:1583-1591; http://dx.doi.org/10.1289/EHP160
How Water Subsidies Affect Air Quality in Abu Dhabi, United Arab Emirates
No full textThe members of the Cooperation Council for the Arab States of the Gulf (GCC) have successfully addressed all water resource problems throughout the region from the supply side. That is, GCC nations have dealt with water scarcity by increasing the supply of water and continuing to provide subsidized water. However, there are few efforts to address and improve urban water supplies through metering, pricing and other efficiency measures to reduce water demand. Instead, the needed potable water comes from the construction of desalination plants that are energy intensive and contribute to air pollution. This paper examines how water subsidies might affect water consumption in Abu Dhabi, United Arab Emirates, and how changes in consumption can in turn affect production levels, which determine total emissions of NOx, SOx, particulate matter, and CO2 into the atmosphere from desalination plants.Master of Science in Environmental Engineerin
Eye movements while viewing narrated videos
No full textWe often encounter dynamic stimuli accompanied by some sort of narrative in our daily lives. Little is known about the basic characteristics of eye movements while viewing dynamic stimuli and nothing is known about the basic characteristics of eye movements while viewing dynamic stimuli accompanied by a narrative. In Experiment 1 eye movements were recorded while subjects viewed 2 minute video clips with: audio narration, captioned narration, no narration, and both captions and audio. Results show that subjects spent half their time reading the caption when it was the only form of narration present and up to 40% of their time reading the caption even in the presence of redundant audio narration, which consisted of a narrator reading the caption verbatim. Subjects explored the display to a much wider extent in the absence of any narration relative to when narration was provided. There was no effect of viewing condition on global characteristics of eye movements such as sizes and pause durations. In experiment 2 eye movements were recorded while subjects viewed 15s video clips with concurrent audio narration, audio narration played immediately preceding the clip, and no narration. Results replicated two major findings from Experiment 1, namely: the tendency to explore a larger portion of the display in the absence of narration, and no effect of narration on saccade sizes or pause durations. The reading of the captions in the presence of redundant audio shows that subjects’ looking patterns were motivated by a desire to acquire information in the simplest way that would aid in interpreting the video. Both experiments show profound influences of the narration on the spatial distribution of landing positions, contributing to the growing body of literature asserting that there are powerful top-down influences on where people decide to look.M.S.Includes bibliographical referencesby Nicholas Ros
The Blase and the Adventure - Seachange Through Simmel
No full textThe aim of this paper is to not engage thoroughly with the Australian movement that has been loosely termed as Seachange, but rather, it is to critically engage with data emerging from this phenomenon using social theoretical perspective from Georg Simmel. The reason for proceeding with this analysis is to provide further credence to the already well acknowledged brilliance of Simmel’s social theory. Furthermore, by doing so, we will be see that this author’s work is more than useful for examining the movements of post/late/high modernity. This is perhaps largely due to the ability of Simmel’s theory to transcend boundaries between disciplines and provide a ‘variety of theoretical perspectives’ (Featherstone, 1991, p2). However, further to this, Simmel’s sociology appears to have an uncanny ability to correspond with much of what is being written on the subject of the aesthetic postmodern culture in contemporary times. Such comparison advocated Simmel’s title as a ‘postmodernist in advance of the discourse’ (Weinstein and Weinstein, 1991, p152). It is not the case of this paper to engage deeply in such a discourse, rather, the simple purpose is to illustrate effectively the deepness of Simmel’s analysis which provides him with the aforementioned title. By using interview data collected by the author himself and through another project run by Dowling (2004), it will be shown that Simmel’s work in the area of the metropolis and leisure, provides sufficient and engaging analysis of Seachange
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