Optimal Calibration of PET Crystal Position Maps Using Gaussian Mixture Models

A method is developed for estimating optimal PET gamma-ray detector crystal position maps, for arbitrary crystal configurations, based on a binomial distribution model for scintillation photon arrival. The approach is based on maximum likelihood estimation of Gaussian mixture model parameters using crystal position histogram data, with determination of the position map taken from the posterior probability boundaries between mixtures. This leads to minimum probability of error crystal identification under the assumed model

MANAGING RISK BY COORDINATING INVESTMENT, MARKETING, AND PRODUCTION STRATEGIES

This study of the farm firm integrates long run investment and financial decisions, and short-run production and marketing decisions into a single decision framework that includes both time and risk. The results suggest that the use of various strategies for managing market risks allow the entrepreneur to accept mores risk in investing and producing; and that an integrated analysis of production, marketing and investment-financing alternatives is essential to make accurate recommendations about risk management strategies.Farm Management, Risk and Uncertainty,

Septage Management In Ohio

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Barriers To Ahtna Athabascans Becoming Public School Educators

Thesis (Ph.D.) University of Alaska Fairbanks, 2012Using a mixed-method phenomenological approach, this cross-cultural study utilizes a non-formalized survey and interviews. Data was gathered and presented in a manner consistent with Ahtna cultural norms and values. Survey data set was analyzed by statistical description. Interview transcripts were analyzed thematically through axial coding. The review of literature and data gathered from Ahtna Athabascan participants identified barriers common to other minorities groups evidenced in Ahtna-specific ways. Through a thematic analysis, the data showed barriers, consequences, benefits, and solutions to Ahtna Athabascans becoming public school educators. Through this study, Ahtna Athabascans expressed an overwhelming desire to see more Ahtna Athabascans teachers in public schools. Among the policy and practical implications identified in the study are the need to improve the quality of K-12 educational experiences for Ahtna youth and improved guidance counseling services. The analysis of the data set provides pathways for future Ahtna-specific research and Ahtna-specific solutions for increasing the number of Ahtna Athabascan teachers in local public schools

Translatio Ganymedis: Reading the Sex Out of Ovid in Alan of Lille's The Plaint of Nature

This article suggests that Alan's complaint, often understood as targeting those guilty of the sin of sodomy, is in fact more interested in condemning the use of allegorical interpretation as a means of evacuating desire from pagan representations of disordered desire, such as in Ovid's Metamorphoses. For Alan, the abduction of Ganymede allegorizes the desire that propels figural interpretation, making the body of Ganymede ultimately another name for the erotic materiality of language in medieval letters. Based on a close reading of Alan's retelling of the Ganymede story, the paper argues that it is the erotic materiality of language that both drives medieval readers to allegorize sexual referents and makes this allegoresis ultimately impossible

A Search for Binary Stars at Low Metallicity

We present initial results measuring the companion fraction of metal-poor stars ([Fe/H]$<-$2.0). We are employing the Lick Observatory planet-finding system to make high-precision Doppler observations of these objects. The binary fraction of metal-poor stars provides important constraints on star formation in the early Galaxy (Carney et al. 2003). Although it has been shown that a majority of solar metallicity stars are in binaries, it is not clear if this is the case for metal-poor stars. Is there a metallicity floor below which binary systems do not form or become rare? To test this we are determining binary fractions at metallicities below [Fe/H]$=-2.0$. Our measurments are not as precise as the planet finders', but we are still finding errors of only 50 to 300 m/s, depending on the signal-to-noise of a spectrum and stellar atmosphere of the star. At this precision we can be much more complete than previous studies in our search for stellar companions.Comment: To appear in conference proceedings,"First Stars III", eds. B. O'Shea, A. Heger & T. Abel. 3 pages, 5 figure

Policy options for improving regional fertilizer markets in West Africa:

A primary motivation for this study is to identify a key set of policy options for improving fertilizer markets in West Africa (among Economic Community of West African States member countries) in ways that ultimately will help improve the efficiency of regional markets and lower the transaction costs and fiscal burdens of increasing fertilizer use in the region. Guided by the 2008 fertilizer crisis, many governments are tempted to impose fertilizer subsidies to reduce fertilizer prices. Yet, in an environment riddled with inefficiencies that contribute to the high costs of using fertilizers, the introduction of subsidies only adds more fiscal burden.To carry out the study, we undertook four country case studies to review the key constraints and bottlenecks along the fertilizer supply chain. The countries were Ghana, Mali, Nigeria, and Senegal, and the research included field visits in 2009 and 2010. The current paper is based on the country case study results, complemented by a literature review and analysis of secondary data sources.common fertilizer market, fertilizer use and supply, harmonization of products and regulations, improved technology, policy environment, regional market integration, structure and performance of markets, supply chain,

In vitro effect of canine hyperimmune sera on TNFa activity

[Introduction]: Septic shock in dogs is caused by cardiovascular and vasomotor failure associated with an uncontrolled intrinsic release of inflammatory mediators [1–5]. The syndrome is characterized by cardiovascular dysfunction, vascular permeability alterations, pulmonary oedema and tissue hypoxia resulting from microthrombi which may culminate in disseminated intravascular coagulation and catastrophic multiple organ failure [6,7]. Systemic bacterial infection, particularly by Gram-negative enterobacteria, haemorrhagic trauma, gastric dilation/volvulus and pancreatitis are the major underlying causes leading tosepsis [8,9]. Because of haemodynamic instability and associated hypovolemia, fluid replacement therapy is generally applied to restore effective circulating volume. The use of fresh frozen plasma has been recommended in cases of coagulopathies as it has been recognized to assist restoration of haemodynamic stability [1,5,10,11]. There is increasing evidence that the drivers of the haemodynamic instability are inflammatory mediators (particularly TNFa) activated primarily by bacterial endotoxin [3,4,12,13]