The effects of test-enhanced learning on long-term retention in AAN annual meeting courses.

OBJECTIVE: We measured the long-term retention of knowledge gained through selected American Academy of Neurology annual meeting courses and compared the effects of repeated quizzing (known as test-enhanced learning) and repeated studying on that retention. METHODS: Participants were recruited from 4 annual meeting courses. All participants took a pretest. This randomized, controlled trial utilized a within-subjects design in which each participant experienced 3 different postcourse activities with each activity performed on different material. Each key information point from the course was randomized in a counterbalanced fashion among participants to one of the 3 activities: repeated short-answer quizzing, repeated studying, and no further exposure to the materials. A final test covering all information points from the course was taken 5.5 months after the course. RESULTS: Thirty-five participants across the 4 courses completed the study. Average score on the pretest was 36%. Performance on the final test showed that repeated quizzing led to significantly greater long-term retention relative to both repeated studying (55% vs 46%; t[34] = 3.28, SEM = 0.03, p = 0.01, d = 0.49) and no further exposure (55% vs 44%; t[34] = 3.16, SEM = 0.03, p = 0.01, d = 0.58). Relative to the pretest baseline, repeated quizzing helped participants to retain almost twice as much of the knowledge acquired from the course compared to repeated studying or no further exposure. CONCLUSIONS: Whereas annual meeting continuing medical education (CME) courses lead to long-term gains in knowledge, when repeated quizzing is added, retention is significantly increased. CME planners may consider adding repeated quizzing to increase the impact of their courses

Integrable Deformations of c^=1\hat{c}=1 Strings in Flux Backgrounds

We study d=2 0A string theory perturbed by tachyon momentum modes in backgrounds with non-trivial tachyon condensate and Ramond-Ramond (RR) flux. In the matrix model description, we uncover a complexified Toda lattice hierarchy constrained by a pair of novel holomorphic string equations. We solve these constraints in the classical limit for general RR flux and tachyon condensate. Due to the non-holomorphic nature of the tachyon perturbations, the transcendental equations which we derive for the string susceptibility are manifestly non-holomorphic. We explore the phase structure and critical behavior of the theory.Comment: 39 pages, 4 figure

Fermion Representation Of The Rolling Tachyon Boundary Conformal Field Theory

A free fermion representation of the rolling tachyon boundary conformal field theory is constructed. The representation is used to obtain an explicit, compact, exact expression for the boundary state. We use the boundary state to compute the disc and cylinder amplitudes for the half-S-brane.Comment: 27 page

Heterotic Strings in Two Dimensions and New Stringy Phase Transitions

We discuss heterotic string theories in two dimensions with gauge groups Spin(24) and Spin(8) x E_8. After compactification the theories exhibit a rich spectrum of states with both winding and momentum. At special points some of these stringy states become massless, leading to new first order phase transitions. For example, the thermal theories exhibit standard thermodynamics below the phase transition, but novel and peculiar behavior above it. In particular, when the radius of the Euclidean circle is smaller than the phase transition point the torus partition function is not given by the thermal trace over the spacetime Hilbert space. The full moduli space of compactified theories is 13 dimensional, when Wilson lines are included; the Spin(24) and Spin(8) x E_8 theories correspond to distinct decompactification limits.Comment: 32 pages; v2: references added, minor change

Hypermoduli Stabilization, Flux Attractors, and Generating Functions

We study stabilization of hypermoduli with emphasis on the effects of generalized fluxes. We find a class of no-scale vacua described by ISD conditions even in the presence of geometric flux. The associated flux attractor equations can be integrated by a generating function with the property that the hypermoduli are determined by a simple extremization principle. We work out several orbifold examples where all vector moduli and many hypermoduli are stabilized, with VEVs given explicitly in terms of fluxes.Comment: 45 pages, no figures; Version submitted to JHE

Permeable conformal walls and holography

We study conformal field theories in two dimensions separated by domain walls, which preserve at least one Virasoro algebra. We develop tools to study such domain walls, extending and clarifying the concept of `folding' discussed in the condensed-matter literature. We analyze the conditions for unbroken supersymmetry, and discuss the holographic duals in AdS3 when they exist. One of the interesting observables is the Casimir energy between a wall and an anti-wall. When these separate free scalar field theories with different target-space radii, the Casimir energy is given by the dilogarithm function of the reflection probability. The walls with holographic duals in AdS3 separate two sigma models, whose target spaces are moduli spaces of Yang-Mills instantons on T4 or K3. In the supergravity limit, the Casimir energy is computable as classical energy of a brane that connects the walls through AdS3. We compare this result with expectations from the sigma-model point of view.Comment: Latex file, 34 pages, 8 figures, uses JHEP3.cls. Typos corrected and references adde

Alpha-Vacua, Black Holes, and AdS/CFT

The Schwarzschild, Schwarzschild-AdS, and Schwarzschild-de Sitter solutions all admit freely acting discrete involutions which commute with the continuous symmetries of the spacetimes. Intuitively, these involutions correspond to the antipodal map of the corresponding spacetimes. In analogy with the ordinary de Sitter example, this allows us to construct new vacua by performing a Mottola-Allen transform on the modes associated with the Hartle-Hawking, or Euclidean, vacuum. These vacua are the `alpha'-vacua for these black holes. The causal structure of a typical black hole may ameliorate certain difficulties which are encountered in the case of de Sitter alpha-vacua. For Schwarzschild-AdS black holes, a Bogoliubov transformation which mixes operators of the two boundary CFT's provides a construction of the dual CFT alpha-states. Finally, we analyze the thermal properties of these vacua.Comment: 40 pages REVTeX and AMSLaTeX, 17 black&white eps figures. v3: references added. v4: details of the pinch singularity avoidance for the string quantization of the Rindler space toy model have been added in both the body of the paper and in a new 7 page appendix. Other clarifications and references added. This is the version accepted for publication in Class. Quant. Gra

Potential Sand and Gravel Resources of the Canton 30 x 60-Minute Quadrangle, Ohio

The Ohio Department of Natural Resources (ODNR), Division of Geological Survey has completed a reconnaissance map showing areas of mineable sand and gravel resources in the Canton, Ohio, 30 x 60-minute 1:100,000-scale quadrangle. The main purpose of this map was to create a reconnaissance-level map that would show the potential for mining sand-and-gravel in this quadrangle. The map shows areas of surficial materials in increments of 10 feet and then differentiates sand, sand and gravel, and ice-contact deposits from finer grained materials, such as glacial till, lacustrine clay and silt, and alluvial materials. The sand and sand-and-gravel units include both surficial and buried outwash and valley train deposits and ice-contact deposits, such as kames, kame terraces, and eskers. This map was created to show the total thickness or accumulation of sand and gravel in the Canton 30 x 60-minute quadrangle. The thickness of sand-and-gravel deposits helps determine if it is economically viable.United States Geological Survey: National Cooperative Geologic Mapping Program, Great Lakes Geologic Mapping Coalitio

Suitablility for Solid-Waste Disposal in the Lorain 30 x 60-Minute Quadrangle

The Ohio Department of Natural Resources (ODNR), Division of Geological Survey has completed a reconnaissance map showing areas suitable for solid waste disposal in the Lorain, Ohio, 30 x 50-minute (1:1,100,000-scale) quadrangle. The main purpose of this map is to provide a reconnaissance level map that shows the relative suitability of various surficial materials for the disposal or containment of solid waste in this quadrangle. Our goal was to create this map from existing ODNR Division of Geological Survey maps and GIS datasets as much as possible. Consequently, the Lorain map is a derivative map based directly from the ODNR Division of Geological Survey SG-2 Series map, Surficial Geology of the Lorain and Put-in-Bay 30 x 60 Minute Quadrangles (Pavey and others, 2005). The SG-2 series features maps based upon polygons that represent a “stack” of mapped unit lithologies and thicknesses. These maps show surficial materials in increments of 10 feet within each polygon across the study area. A set of queries were run in ESRI ArcGIS to determine the range of thickness and nature of the sediments. The main premise of this map is to specify areas of thick, fine-grained glacial till and glaciolacustrine silt and clay deposits for solid-waste disposal and containment. A minimum of 30 feet of fine-grained material was deemed necessary for waste disposal for areas where the drift overlies shale; siltstone; or interbedded, shaley limestone. If the fine-grained material was directly overlying an aquifer, the minimum required thickness was increased to 50 feet. Aquifers included sand and gravel, sandstone, limestone, and dolomite. Areas with over 20 feet of sand and gravel or sand at the surface (e.g., kames, beach ridges) were excluded as were areas with alluvium (active streams) and organic deposits at the land surface. The main factor in the decision-making process was to have adequate fine-grained materials overlying the aquifers.United States Geological Survey, National Cooperative Geologic Mapping Program, Great Lakes Geologic Mapping Coalitio

The Final Fate of the Rolling Tachyon

We propose an alternative interpretation of the boundary state for the rolling tachyon, which may depict the time evolution of unstable D-branes in string theory. Splitting the string variable in the temporal direction into the classical part, which we may call "time" and the quantum one, we observe the time dependent behaviour of the boundary. Using the fermion representation of the rolling tachyon boundary state, we show that the boundary state correctly describes the time-dependent decay process of the unstable D-brane into a S-brane at the classical level.Comment: 9 pages, revte