10,609 research outputs found
The Schnitzel Squad
Postcard from Cruz Morey, during the Linfield College Semester Abroad Program at the Austro-American Institute of Education in Vienna, Austri
Vertical Integration in Multi-commodity Energy Markets
In a simple energy-market structure consisting of natural gas and electricity suppliers, suppliers exercise market power by adjusting their production levels to influence the market price. This is done with the aim of maximizing their individual profits. This paper examines the impact of vertical integration, whereby firms supply both natural gas and electricity, on market efficiency. Market equilibria, which is the point at which no firm has incentive to deviate unilaterally, was modeled using a computational approach. Stylized profit-maximization problems were examined with vertically integrated and dis-integrated firms using a quantity-setting Nash-Cournot framework. Karush-Kuhn-Tucker (KKT) conditions are used to characterize optimal solutions to the firms' profit-maximization problems. Combining the KKT conditions of all of the firms allows us to compute market equilibria efficiently. The complementarity framework is used to examine the incentives of integrated and dis-integrated firms to exercise market power in one or both of the markets. Comprehensive case studies that are reflective of real-world energy systems are used to examine the impacts of potential mergers between natural gas and electric firms on market efficiency. This work can inform policy makers and regulators in determining how markets should be structured to ensure increased efficiency. Policy makers and regulators could employ a modeling technique, such as the one developed in this paper, to screen potential vertical mergers in energy and other market settings.No embargoAcademic Major: Industrial and Systems Engineerin
Maintaining binding in working memory: Comparing the effects of intentional goals and incidental affordances
Much research on memory for binding depends on incidental measures. However, if encoding associations benefits from conscious attention, then incidental measures of binding memory might not yield a sufficient understanding of how binding is accomplished. Memory for letters and spatial locations was compared in three within-participants tasks, one in which binding was not afforded by stimulus presentation, one in which incidental binding was possible, and one in which binding was explicitly to be remembered. Some evidence for incidental binding was observed, but unique benefits of explicit binding instructions included preserved discrimination as set size increased and drastic reduction in false alarms to lures that included a new spatial location and an old letter. This suggests that substantial cognitive benefits, including enhanced memory for features themselves, might occur through intentional binding, and that incidental measures of binding might not reflect these advantages. (C) 2011 Elsevier Inc. All rights reserved
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Understanding How Undergraduate Students Experience and Manage Stress: Implications for Teaching and Learning Anthropology
Research has shown that negative effects of stress on undergraduate students can have a significant impact on their college experience. Most of what we know about this topic is quantitative, based on surveys that provide self-reported information for large numbers of college students. The present study provides an in-depth qualitative perspective on college students and stress that foregrounds the voices of these emerging adults. Specifically, in this article we (a) share findings from a study using qualitative methods to examine how college students experience and manage stress and (b) provide strategies to help anthropology instructors design and manage their classes to improve learning for students under chronic stress
A Lower Bound For Depths of Powers of Edge Ideals
Let be a graph and let be the edge ideal of . Our main results in
this article provide lower bounds for the depth of the first three powers of
in terms of the diameter of . More precisely, we show that \depth R/I^t
\geq \left\lceil{\frac{d-4t+5}{3}} \right\rceil +p-1, where is the
diameter of , is the number of connected components of and . For general powers of edge ideals we showComment: 21 pages, to appear in Journal of Algebraic Combinatoric
Embedded Associated Primes of Powers of Square-free Monomial Ideals
An ideal I in a Noetherian ring R is normally torsion-free if
Ass(R/I^t)=Ass(R/I) for all natural numbers t. We develop a technique to
inductively study normally torsion-free square-free monomial ideals. In
particular, we show that if a square-free monomial ideal I is minimally not
normally torsion-free then the least power t such that I^t has embedded primes
is bigger than beta_1, where beta_1 is the monomial grade of I, which is equal
to the matching number of the hypergraph H(I) associated to I. If in addition I
fails to have the packing property, then embedded primes of I^t do occur when
t=beta_1 +1. As an application, we investigate how these results relate to a
conjecture of Conforti and Cornu\'ejols.Comment: 15 pages, changes have been made to the title, introduction, and
background material, and an example has been added. To appear in JPA
Exertional sickling: Questions and controversy
Sickle cell trait (SCT) occurs in about 8% of African-Americans and is often described to be of little clinical consequence. Over time, a number of risks have emerged, and among these are rare but catastrophic episodes of sudden death in athletes and other individuals associated with physical activities which is often described as exercise collapse associated with sickle trait (ECAST). Despite an epidemiologic link between SCT and sudden death as well as numerous case reports in both medical literature and lay press, no clear understanding of the key pathophysiologic events has been identified. Strategies for identification of individuals at risk and prevention of ECAST have been both elusive and controversial. Stakeholders have advocated for different approaches to this issue particularly with regard to screening for hemoglobin S. Furthermore, the recommendations and guidelines that are in place for the early recognition of ECAST and the prevention and treatment of the illness are not well defined and remain fragmented. Among the cases identified, those in collegiate football players in the United States are often highlighted. This manuscript examines these case studies and the current recommendations to identify areas of consensus and controversy regarding recommendations for prevention, recognition and treatment of ECAST
First Collection Records of \u3ci\u3eHippodamia Variegata\u3c/i\u3e (Coleoptera: Coccinellidae) in Minnesota Corn and Soybean
The coccinellid Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae) is a relatively recent addition to the North American coccinellid fauna. This species was first reported in 1984 near Montreal, Quebec (Gordon 1987). Since then, its range has expanded beyond northeastern North America with the newest records in the midwestern United States, including Michigan (Gardiner and Parson 2005), Ohio (Pavuk et al. 2007), Wisconsin (Williams and Young 2009), and most recently South Dakota (Hesler and Lundgren 2011). Here we provide the first records of H. variegata in Minnesota. In addition, our records further define the movement pattern of this beetle across the Midwest by documenting its presence in the gap between Wisconsin and South Dakota
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