Leading for Learning Sourcebook: Concepts and Examples

Provides a detailed discussion of ideas and methods that educators can use to enhance leadership in learning. Offers examples of leaders using the ideas and tools for assessment, planning, and teaching. Includes four annotated longitudinal cases

Neutron Spectroscopy Using Rubberized Eu:LiCAF Wafers

With the increasing cost and decreasing availability of 3He, there have been many efforts to find alternative neutron detection materials. Lithium calcium aluminum fluoride (LiCAF) enriched to 95% 6Li doped with europium was evaluated here as a replacement material for 3He, based on the absorption of thermalized neutrons by the 6Li and subsequent energy release of the 6Li(n,t)4He reaction. Wafers 0.5 cm thick, consisting of LiCAF crystals in a rubberized matrix, were embedded with wavelength shifting fibers (WSF) and mated to silicon photo-multipliers (SiPMs) to measure the photon response in a flux of neutrons from a DD neutron generator. Excellent discrimination was realized between neutrons and gammas, and both pulse-height discrimination and pulse-shape analysis were explored. A Figure of Merit (FoM) of 1.03 was achieved. Custom electronics were built to bias the SiPMs, then amplify, filter, discriminate, and digitize the LiCAF/WSF scintillation photons, resulting in a digital pulse that can easily be counted with any microcontroller. After evaluation of the Eu:LiCAF, a portable ten-layer neutron spectrometer was fabricated from the rubberized wafers. A layer of high density polyethylene (HDPE) was used as a neuton moderator between each layer. Neutrons entering the spectrometer are downscattered and absorbed by the lithium in a wafer of rubberized Eu:LiCAF; the layer in which the absorption occurs is dependent on the incident neutron\u27s energy. A library of neutron response curves was created using Geant4 and applied with the maximum entropy principle algorithm, MAXED, to unfold the experimentally acquired data. The spectrometer was commissioned using two DD generators and a 252Cf source. This research demonstrated that Eu:LiCAF is a promising potential replacement for 3He and shows excellent promise for neutron spectroscopy applications

Neutron Spectroscopy Using LiF Thin-Film Detectors

A stacked array of segmented micro-structured semiconductor neutron detectors (MSNDs) has been fabricated to perform as a neutron spectrometer simultaneously capable of differentiating fast and thermal neutrons. The MSND devices consist of thin-film perforated diodes constructed from LiF powder back-filled into an etched silicon wafer. Geant4 simulations demonstrate than an eight-layer spectrometer consisting of alternating layers of MSND and hydrogenous moderator can successfully resolve neutron energies at a resolution dependent upon the number of layers and the thickness of the adjacent moderating materials. The simulated spectrometer response was compared to that obtained experimentally with mono-energetic neutrons from a D+D neutron generator. The commissioning tests of the spectrometer reveal that the energy of a mono-energetic neutron source can be identified to within + or -1 MeV. Following the commissioning tests, the spectrometer was used to characterize the poly-energetic neutron spectrum of a plutonium-beryllium neutron source

Quantum Inequalities on the Energy Density in Static Robertson-Walker Spacetimes

Quantum inequality restrictions on the stress-energy tensor for negative energy are developed for three and four-dimensional static spacetimes. We derive a general inequality in terms of a sum of mode functions which constrains the magnitude and duration of negative energy seen by an observer at rest in a static spacetime. This inequality is evaluated explicitly for a minimally coupled scalar field in three and four-dimensional static Robertson-Walker universes. In the limit of vanishing curvature, the flat spacetime inequalities are recovered. More generally, these inequalities contain the effects of spacetime curvature. In the limit of short sampling times, they take the flat space form plus subdominant curvature-dependent corrections.Comment: 18 pages, plain LATEX, with 3 figures, uses eps

Effects of Community Exercise Therapy on Metabolic, Brain, Physical, and Cognitive Function Following Stroke : A Randomized Controlled Pilot Trial

© The Author(s) 2014.Peer reviewedPostprintPostprin

Scalar Field Quantum Inequalities in Static Spacetimes

We discuss quantum inequalities for minimally coupled scalar fields in static spacetimes. These are inequalities which place limits on the magnitude and duration of negative energy densities. We derive a general expression for the quantum inequality for a static observer in terms of a Euclidean two-point function. In a short sampling time limit, the quantum inequality can be written as the flat space form plus subdominant correction terms dependent upon the geometric properties of the spacetime. This supports the use of flat space quantum inequalities to constrain negative energy effects in curved spacetime. Using the exact Euclidean two-point function method, we develop the quantum inequalities for perfectly reflecting planar mirrors in flat spacetime. We then look at the quantum inequalities in static de~Sitter spacetime, Rindler spacetime and two- and four-dimensional black holes. In the case of a four-dimensional Schwarzschild black hole, explicit forms of the inequality are found for static observers near the horizon and at large distances. It is show that there is a quantum averaged weak energy condition (QAWEC), which states that the energy density averaged over the entire worldline of a static observer is bounded below by the vacuum energy of the spacetime. In particular, for an observer at a fixed radial distance away from a black hole, the QAWEC says that the averaged energy density can never be less than the Boulware vacuum energy density.Comment: 27 pages, 2 Encapsulated Postscript figures, uses epsf.tex, typeset in RevTe

Quantum Inequalities and Singular Energy Densities

There has been much recent work on quantum inequalities to constrain negative energy. These are uncertainty principle-type restrictions on the magnitude and duration of negative energy densities or fluxes. We consider several examples of apparent failures of the quantum inequalities, which involve passage of an observer through regions where the negative energy density becomes singular. We argue that this type of situation requires one to formulate quantum inequalities using sampling functions with compact support. We discuss such inequalities, and argue that they remain valid even in the presence of singular energy densities.Comment: 18 pages, LaTex, 2 figures, uses eps

The Temporal Dynamics Between Work Stressors And Health Behaviors

Applying dynamic equilibrium theory (DET), we examined the temporal dynamics between role overload and three health behaviors (sleep, diet, physical activity). Participants (N = 781) completed five surveys, with 1-month lag between assessments, and the data were analyzed using general cross-lagged panel modeling (GCLM). Results indicated that people had stable health behavior patterns (i.e., there were strong unit effects) that were related to stable role overload patterns (i.e., the chronic role overload and health behavior factors were significantly related). Furthermore, while monthly increases (impulses) in role overload had a negative effect on health behaviors concurrently, health behaviors quickly adapted or regressed back toward previous levels (i.e., there were weak autoregressive and cross-lagged effects after accounting for chronic factors). Impulse response functions were created to show the specific proportion of the initial impulse effect that persisted on each health behavior over time. The results of these response functions indicated that diet and physical activity regressed back to previous levels within 1 month, whereas sleep regressed back to previous levels within 2 months. Collectively, our results suggest that people engage in fairly stable patterns of health behaviors and that these patterns are partly determined by chronic role overload. Our results also suggest that people are generally resilient to temporary changes in role overload, such that the resulting immediate changes in behavior do not persist or become habitual. These results underscore the strength of habits and the resistance to health behavior change, as well as provide support for the use of GCLM for studying DET

Quantum Inequalities for the Electromagnetic Field

A quantum inequality for the quantized electromagnetic field is developed for observers in static curved spacetimes. The quantum inequality derived is a generalized expression given by a mode function expansion of the four-vector potential, and the sampling function used to weight the energy integrals is left arbitrary up to the constraints that it be a positive, continuous function of unit area and that it decays at infinity. Examples of the quantum inequality are developed for Minkowski spacetime, Rindler spacetime and the Einstein closed universe.Comment: 19 pages, 1 table and 1 figure. RevTex styl

Conceptualizing and Measuring Risk Perceptions of Skin Cancer: A Review

Background: Perceived risk is commonly conceived as a joint function of the perceived evaluations about the probability estimate of a negative outcome, and the perceived seriousness of the consequences of that negative outcome. Theories typically posit that once people perceive their vulnerability to health risks or outcomes, they form intentions to take preventive actions to reduce their risk. This theoretical proposition is not supported in skin cancer preventative behavior studies, which could be due to improper measurement of perceived risk. Purpose and Methods: The purpose of this manuscript was to assess how risk perception of skin cancer has been conceptualized and measured in the literature to date. Literature retrieval was facilitated through EBSCO, PubMed, PsycInfo, MEDLINE, and ERIC databases. Twenty potentially relevant articles were identified for this review. Results: In the literature, skin cancer risk has been operationalized in two ways: absolute risk and comparative risk. However, these measures have some serious limitations. For example, there is great uncertainty regarding the quality of risk perception measurements (i.e., whether the items used to measure perceived risk are reliable and valid). Future studies are warranted to better understand the significance of using conditional risk measures