4,255 research outputs found

    Semiclassical Gravity in the Far Field Limit of Stars, Black Holes, and Wormholes

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    Semiclassical gravity is investigated in a large class of asymptotically flat, static, spherically symmetric spacetimes including those containing static stars, black holes, and wormholes. Specifically the stress-energy tensors of massless free spin 0 and spin 1/2 fields are computed to leading order in the asymptotic regions of these spacetimes. This is done for spin 0 fields in Schwarzschild spacetime using a WKB approximation. It is done numerically for the spin 1/2 field in Schwarzschild, extreme Reissner-Nordstrom, and various wormhole spacetimes. And it is done by finding analytic solutions to the leading order mode equations in a large class of asymptotically flat static spherically symmetric spacetimes. Agreement is shown between these various computational methods. It is found that for all of the spacetimes considered, the energy density and pressure in the asymptotic region are proportional to 1/r^5 to leading order. Furthermore, for the spin 1/2 field and the conformally coupled scalar field, the stress-energy tensor depends only on the leading order geometry in the far field limit. This is also true for the minimally coupled scalar field for spacetimes containing either a static star or a black hole, but not for spacetimes containing a wormhole.Comment: 43 pages, 2 figures. Reference added, minor changes, PRD versio

    A Statewide Student Teacher Evaluation Tool

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    Examining the Reliability and Validity of Teacher Candidate Evaluation Instruments

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    The webinar is designed for faculty and staff of educator preparation programs (EPPs), state education agency (SEA) staff responsible for oversight of teacher preparation and certification, and others interested in the evaluation of teacher candidates. The content of the webinar will focus on the Council for the Accreditation of Educator Preparation (CAEP) program standards that require that EPPs use evaluation instruments with evidence of reliability and validity. The content will also include two studies that examined the reliability and validity of a teacher candidate evaluation instrument

    Integrated modeling and simulation of lunar exploration campaign logistics

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007.Includes bibliographical references (p. 138-140).As NASA prepares to establish a manned outpost on the lunar surface, it is essential to consider the logistics of both the construction and operation of this outpost. This thesis presents an interplanetary supply chain management and logistics planning and simulation software tool, SpaceNet, developed to assist mission architects, planners, systems engineers and logisticians in performing analysis on what will be needed to support future human exploration missions, primarily in the Earth-Moon-Mars system. Also presented in this thesis are the results of numerous trade studies performed using SpaceNet to determining the best mix of mission types (pre-positioning, carry-along and resupply) to achieve sustainable, robust space exploration. These trade studies focus on analyzing notional mission architectures in terms of scientific benefit, logistical overhead and robustness to campaign level risks such as flight delays, flight cancellations and uncertain demand parameters. The significant findings presented in this thesis broadly fall into three categories: a demonstration of the value of integrated modeling and simulation of campaign logistics, the best logistics strategy for the establishment of a lunar outpost, and suggestions to reduce campaign level risk.(cont.) The development of SpaceNet has made several key contributions to the field of space logistics, primarily in the creation of a set of ten function-based classes of supply for human space exploration, the detailed modeling of demand parameters at the supply class level, and the ability to model entire campaigns of missions and to compare these campaigns using the measures of effectiveness developed. Through the campaign analysis it is shown that the Lunar Architecture Team (LAT) Option 1 lunar mission architecture is ~11,500 kg short of being able to support four crew members for the proposed durations. It is also shown that the inclusion of at least two unmanned cargo missions makes the architecture sustainable. The campaign level risk analysis research performed demonstrates that the best way to protect against schedule and demand uncertainty is to maintain at least a 90-day safety stock of consumables at the lunar base (~2100 kg for a crew of four).by Sarah A. Shull.S.M

    Mapping the Nephron Exercise Incorporates Multiple Learning Strategies

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    Introduction: Understanding the location and action of nephron transporters and channels is important to the understanding of renal function. As each region of the nephron is unique in its inclusion of specific transporters and channels, mapping of the nephron is an effective first step in understanding overall nephron processing. We describe a small-group, active-learning exercise that facilitates students' ability to understand renal processing within each region of the nephron. Methods: Following an overview lecture on renal transporters and channels, small groups of students worked cooperatively to map the nephron. This 2-hour, collaborative exercise was developed to reinforce key concepts in renal processing of ions and nutrients and, at the same time, utilize effective learning strategies. Learning strategies incorporated in this exercise include small-group collaboration, peer teaching, retrieval practice using an audience response system, and elaboration through discussion. Results: Written examination was used to assess student understanding. Students demonstrated higher performance on a subset of questions related to this learning activity compared to the overall exam. Highly positive feedback was provided by a convenience sample of students completing an anonymous survey. Discussion: This nephron-mapping exercise was an effective means to promote synthesis and analysis of lecture content and engage students in methods that enhance learning

    Application of Structured Decision Making to Wildlife Management in Montana

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    Good decision-making is essential to conserving wildlife populations. Whereas there may be multiple ways to address a problem, perfect solutions rarely exist. Managers are therefore tasked with identifying optimal decisions that will best achieve desired outcomes. Structured decision making (SDM) is a method of decision analysis used to identify the most effective, efficient, and realistic optimal decisions while accounting for values and priorities of the decision maker. The stepwise process includes identifying the management problem, defining objectives for solving the problem, developing alternative approaches to achieve the objectives, and formally evaluating which alternative is most likely to accomplish the objectives. The SDM process can be more effective than informal decision-making because it provides a transparent way to quantitatively evaluate decisions for addressing multiple management objectives while incorporating science, uncertainty, and risk tolerance. We illustrate the application of this process to management needs, including an SDM-based decision tool developed to identify optimal decisions for proactively managing risk of pneumonia epizootics in bighorn sheep (Ovis canadensis). Pneumonia epizootics are a major challenge for managers, including in terms of knowing how or when to manage risk. The decision tool facilitates analysis of alternative decisions for how to manage herds based on predictions from a risk model, herd-specific objectives, and predicted costs and benefits of each alternative. Managers can be confident resulting decisions are most effective, efficient, and realistic because they explicitly account for important considerations managers implicitly weigh when making decisions, including competing management objectives, uncertainty in potential outcomes and risk tolerance

    Individual differences in susceptibility to false memories: The effect of memory specificity

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    Previous research has highlighted the wide individual variability in susceptibility to the false memories produced by the Deese/Roediger-McDermott (DRM) procedure [Deese, J. (1959). On the prediction of occurrence of particular verbal intrusions in immediate recall. Journal of Experimental Psychology, 58, 17–22; Roediger, H. L., III, & McDermott, K. B. (1995). Creating false memories: Remembering words not presented in lists. Journal of Experimental Psychology: Learning, Memory, & Cognition, 21, 803–814]. The current study investigated whether susceptibility to false memories is influenced by individual differences in the specificity of autobiographical memory retrieval. Memory specificity was measured using the Sentence Completion for Events from the Past Test (SCEPT) [Raes, F., Hermans, D., Williams, J. M. G., & Eelen, P. (2007). A sentence completion procedure as an alternative to the Autobiographical Memory Test for assessing overgeneral memory in non-clinical populations. Memory, 15, 495-507]. Memory specificity did not correlate with correct recognition, but a specific retrieval style was positively correlated with levels of false recognition. It is proposed that the contextual details that frequently accompany false memories of nonstudied lures are more accessible in individuals with specific retrieval styles

    Language rights and Indigenous human rights in Central Australia

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    In this Policy Insights paper we use the successful COVID-19 health messaging in an Indigenous language as a lever to explore the ways in which communication rights for Anangu are coupled with their collective rights as Indigenous Australians, as a particular strand of human rights. There is a fundamental relationship between the recognition of language rights and Anangu being able to more readily realise other human rights. This extends beyond issues of comprehension and enabling freedom of opinion and expression in language. As we discuss in this paper, it also ultimately extends to being enabled to access the core principles of universal human rights in the local vernacular in order to render them locally meaningful. The human rights activist and philosopher Boaventura de Sousa Santos, has long argued for a human rights discourse that can embrace different cultures and religions, which he articulates as a multicultural human rights. In this paper we begin to articulate what this might look like for Anangu, taking as a foundational platform communication rights

    Molecular Mechanisms of Nonalcoholic Fatty Liver Disease: Potential Role for 12-Lipoxygenase

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    Nonalcoholic fatty liver disease (NAFLD) is a spectrum of pathologies associated with fat accumulation in the liver. NAFLD is the most common cause of liver disease in the United States, affecting up to a third of the general population. It is commonly associated with features of metabolic syndrome, particularly insulin resistance. NAFLD shares the basic pathogenic mechanisms with obesity and insulin resistance, such as mitochondrial, oxidative and endoplasmic reticulum stress. Lipoxygenases catalyze the conversion of poly-unsaturated fatty acids in the plasma membrane—mainly arachidonic acid and linoleic acid—to produce oxidized pro-inflammatory lipid intermediates. 12-Lipoxygenase (12-LOX) has been studied extensively in setting of inflammation and insulin resistance. As insulin resistance is closely associated with development of NAFLD, the role of 12-LOX in pathogenesis of NAFLD has received increasing attention in recent years. In this review we discuss the role of 12-LOX in NAFLD pathogenesis and its potential role in emerging new therapeutics
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