2012-13 Arkansas Test Results

In early August, the Arkansas Department of Education (ADE) released the 2012-2013 test score results. The following brief will highlight the results of these tests, compare achievement scores over time, and provide a glimpse of regional achievement results for the following exams: Benchmark Exam (Grades 3-8) End-of-Course Exam (Algebra I, Geometry, Biology, and Grade 11 Literacy). Iowa Test of Basic Skills (Grades 1-9

Correlations and Counting Statistics of an Atom Laser

We demonstrate time-resolved counting of single atoms extracted from a weakly interacting Bose-Einstein condensate of $^{87}$Rb atoms. The atoms are detected with a high-finesse optical cavity and single atom transits are identified. An atom laser beam is formed by continuously output coupling atoms from the Bose-Einstein condensate. We investigate the full counting statistics of this beam and measure its second order correlation function $g^{(2)}(\tau)$ in a Hanbury Brown and Twiss type experiment. For the monoenergetic atom laser we observe a constant correlation function $g^{(2)}(\tau)=1.00\pm0.01$ and an atom number distribution close to a Poissonian statistics. A pseudo-thermal atomic beam shows a bunching behavior and a Bose distributed counting statistics

Random Bit Multilevel Algorithms for Stochastic Differential Equations

We study the approximation of expectations \E(f(X)) for solutions $X$ of SDEs and functionals $f \colon C([0,1],\R^r) \to \R$ by means of restricted Monte Carlo algorithms that may only use random bits instead of random numbers. We consider the worst case setting for functionals $f$ from the Lipschitz class w.r.t.\ the supremum norm. We construct a random bit multilevel Euler algorithm and establish upper bounds for its error and cost. Furthermore, we derive matching lower bounds, up to a logarithmic factor, that are valid for all random bit Monte Carlo algorithms, and we show that, for the given quadrature problem, random bit Monte Carlo algorithms are at least almost as powerful as general randomized algorithms

Random Bit Quadrature and Approximation of Distributions on Hilbert Spaces

We study the approximation of expectations \E(f(X)) for Gaussian random elements $X$ with values in a separable Hilbert space $H$ and Lipschitz continuous functionals $f \colon H \to \R$. We consider restricted Monte Carlo algorithms, which may only use random bits instead of random numbers. We determine the asymptotics (in some cases sharp up to multiplicative constants, in the other cases sharp up to logarithmic factors) of the corresponding $n$-th minimal error in terms of the decay of the eigenvalues of the covariance operator of $X$. It turns out that, within the margins from above, restricted Monte Carlo algorithms are not inferior to arbitrary Monte Carlo algorithms, and suitable random bit multilevel algorithms are optimal. The analysis of this problem leads to a variant of the quantization problem, namely, the optimal approximation of probability measures on $H$ by uniform distributions supported by a given, finite number of points. We determine the asymptotics (up to multiplicative constants) of the error of the best approximation for the one-dimensional standard normal distribution, for Gaussian measures as above, and for scalar autonomous SDEs

Disputing Arbitration Clauses in International Insurance Agreements: Problems with the Self-Execution Framework

This Article argues that the self-execution framework that courts have adopted—and scholars have endorsed—in addressing whether McCarran-Ferguson enables states to reverse preempt the New York Convention is inadequate. First, the Article addresses the interpretive question: what is an “Act of Congress” under McCarran-Ferguson? By examining whether a treaty is self or non-self-executing, courts discard proper methods of statutory interpretation. Second, the Article argues that courts have failed to satisfactorily transpose the self-execution doctrine—which has been relevant only in determining whether a treaty confers a legally enforceable right in the U.S.—into the context of the conflict between McCarran-Ferguson and the New York Convention. Finally, the Article argues that the treaty’s self-executing or non-self-executing status is irrelevant because enforcing an international arbitration agreement under the New York Convention implicates Chapter 2 of the Federal Arbitration Act—which implemented the Convention—and McCarran-Ferguson permits a state law to reverse preempt an Act of Congress. Since the self-execution approach fails to answer the interpretive problem posed by McCarran-Ferguson, practitioners and courts should adopt an alternative approach that is more consistent with proper methods of statutory interpretation. Part II of this Article sets up the framework in which the previously mentioned legal question arises. It reviews federal law governing the enforceability of arbitration agreements, including the Federal Arbitration Act, the New York Convention, and McCarran-Ferguson’s reverse preemption scheme as it relates to federal arbitration law. Part III introduces the disagreement between federal courts as to whether McCarran-Ferguson permits states to reverse preempt the implementation of the New York Convention to the extent that it may be applied to the business of insurance. Part IV argues that the methodology of resolving this disagreement—which currently centers on whether or not the New York Convention is a self-executing treaty—inadequately addresses Congress’s purpose in enacting McCarran-Ferguson. It further contends that regardless of the self-executing or non-self-executing status of the New York Convention, McCarran-Ferguson protects state law from preemption by the substantive guarantees of the New York Convention because an Act of Congress, Chapter 2 of the Federal Arbitration Act, provides the sole mechanism for the enforcement and recognition of international arbitration agreements under the Convention. Part V briefly concludes this Article

Unravelling the formation of Hells Bells: underwater speleothems from the Yucatán Peninsula in Mexico

Hells Bells are unique bell-shaped underwater speleothems recently discovered in deep meromictic sinkholes (cenotes) on the Yucatán Peninsula, Mexico. In order to unravel the underwater growth of Hells Bells and identify the mechanism of subaqueous calcite precipita-tion, several deep meromictic cenotes with and without Hells Bells were investigated. Compre-hensive hydro-, bio- and geochemical analyses of the water bodies and Hells Bells specimens including stable carbon isotope analyses, petrographic examination, U series age-dating, aqui-fer monitoring and microbiological investigations, resulted in a consistent hypothesis on Hells Bells formation. The subaqueous authigenic calcite precipitation in cenotes with Hells Bells is most likely promoted by biogeochemical processes within the narrow 1–2 m thick pelagic re-doxcline immediately above the halocline. Chemolithoautotrophy and incomplete microbial oxidation of sulfide to zero-valent sulfur via proton-consuming sulfide oxidation were identi-fied as dominant biogeochemical processes within the redoxcline. Both processes favor authi-genic calcite precipitation by increasing the pH of the surrounding water. A low degree of con-vection within the water body is identified as crucial hydrogeological prerequisite for the devel-opment of pelagic redoxclines, in which biogeochemical conditions favoring calcite precipita-tion prevail. Furthermore, in order to preserve the authigenic calcite formed in the redoxcline and build Hells Bells, a dynamic elevation of the halocline is hypothesized. Suitable conditions for Hells Bells formation are likely to be encountered in other deep stratified cenotes on the Yucatán Peninsula that are so far unexplored or unrecognized. Age-dating indicates that Hells Bells growth is an ongoing process covering the present to previous interglacial phases from ~0.1 12.5 and ~90–120 ka BP, respectively, outlasting aerial exposure during glacial sea level low stands. Eventually, isotope-geochemical and age-dating analyses reveal a great potential of Hells Bells as a geoarchive for reconstructing minimum sea level elevations, the development of the Yucatán Karst Aquifer and vegetation changes on the Yucatán Peninsula

Horizontal and vertical forest complexity interact to influence potential fire behavior

2022 Spring.Includes bibliographical references.Wildland fire behavior is a dynamic process controlled by complex interactions among fuels, weather, and topography. There is significant need to better understand the role of fuels and, particularly, complex arrangements of fuels, on potential fire behavior and effects as a there is a growing emphasis on forest treatments that emulate the heterogenous structures of historical forest ecosystems. Ideally such treatments are intended to reduce fire hazard while concurrently improving resilience to a wide range of disturbance agents and restoring the natural ecosystem dynamics that maintained these forest structures. One way to evaluate how the complex forest structures created by these treatments will influence fire behavior are modeling approaches that account for dynamic interactions between fire, fuels, and wind. These physical fire models build from computational fluid dynamics methods to include processes of heat transfer, vegetative fuel dehydration and pyrolysis, and gas phase ignition and combustion. In this work, several aspects of horizontal and vertical forest structure were evaluated to understand how spatial complexity influences fire behavior, with a particular emphasis on the transition of a surface fire into tree crowns. I used a combination of spatially explicit field data and a physics-based wildfire model, the Wildland-Urban Interface Fire Dynamics Simulator (WFDS), to deepen our fundamental understanding of fire behavior, inform the design of forest treatments that aim to achieve a variety of ecological and social objectives, and develop hypotheses related to the pattern-process feedbacks that contributed to the maintenance of resilient forests across millennia. Chapter 2 presents a simulation study focused on the relationship between horizontal forest structure and surface to crown heat transfer and crown fire initiation. The results indicated that relative to larger 7- and 19-tree groups, isolated individual trees and 3-tree groups had greater convective cooling and reduced canopy heat flux. Because isolated individuals and 3-tree groups were exposed to less thermal energy, they required a greater surface fireline intensity to initiate torching and had less crown consumption than trees within larger groups. Similarly, I found that increased crown separation distance between trees reduced the net heat flux leading to reduced ignition potential. These findings identify the potential physical mechanisms responsible for supporting the complex forest structures typical of high-frequency fire regimes and may be useful for managers designing fuel hazard reduction and ecological restoration treatments. Chapter 3 extends chapter 2 by investigating how different levels and types of vertical heterogeneity influence crown fire transition and canopy consumption within tree groups. These results show the importance of fuel stratum gap (or canopy base height) on vertical fire propagation, however vertical fire propagation was mediated by the level of horizontal connectivity in the upper crown layers. This suggests that the fuel stratum gap cannot fully characterize the torching hazard. The results also indicate that as the surface fire line intensity increases, the influence of horizontal connectivity on canopy consumption is amplified. At the scale of individual tree groups, the perceived hazard of small, understory trees and vertical fuel continuity may be offset by lower horizontal continuity (or canopy bulk density) within the midstory and overstory crown layers. Chapter 4 compares outcomes from four real-world forest treatments that cover a range of potential treatment approaches to evaluate their impacts of forest spatial pattern and potential fire behavior. My results indicate that restoration treatments created greater vertical and horizontal structural complexity than the fuel hazard reduction treatments but resulted in similar reductions to potential fire severity. However, the restoration treatments did increase the surface fire rate of spread which suggests some potential fire behavior tradeoffs among treatment approaches. Overall, these results suggest the utility of restoration treatments in achieving a wide range of management objectives, including fire hazard reduction, and that they can be used in concert with traditional fuel hazard reduction treatments to reduce landscape scale fire risk. Together this work shows that tree spatial pattern can significantly influence crown fire initiation and canopy consumption through alterations to net heat transfer and feedbacks among closely spaced trees. At the scale of the tree group these results suggest that larger tree groups may sustain higher levels of canopy consumption and mortality as they are easier to ignite and, in cases with small separation between crowns, can sustain horizontal spread resulting in density-depended crown damage. These findings carry over to vertically complex groups where the spatial relationship between small, understory trees and larger, overstory trees has a large impact on the ability of fire to be carried vertically. Further, in these vertically complex groups reducing the density (and/or increasing the horizontal separation) of the overstory trees, resulted in lower rates of crown fuel consumption, therefore, mitigating some of the "laddering" effect caused by the presence of small understory trees. These complex interactions between vertical and horizontal aspects of stand structure were born out in my evaluation of the measured forest treatments, where similar crown fire behavior reductions were observed across various stand structures. Overall, this work shows that forest managers can apply treatments to achieve a wide range of ecological benefits while simultaneously increasing fire resistance and resilience

Multiscale modeling of dislocations: Combining peridynamics with gradient elasticity

Modeling dislocations is an inherently multiscale problem as one needs to simultaneously describe the high stress fields near the dislocation cores, which depend on atomistic length scales, and a surface boundary value problem which depends on boundary conditions on the sample scale. We present a novel approach which is based on a peridynamic dislocation model to deal with the surface boundary value problem. In this model, the singularity of the stress field at the dislocation core is regularized owing to the non-local nature of peridynamics. The effective core radius is defined by the peridynamic horizon which, for reasons of computational cost, must be chosen much larger than the lattice constant. This implies that dislocation stresses in the near-core region are seriously underestimated. By exploiting relationships between peridynamics and Mindlin-type gradient elasticity, we then show that gradient elasticity can be used to construct short-range corrections to the peridynamic stress field that yield a correct description of dislocation stresses from the atomic to the sample scale.Comment: 21 pages, 9 figure

Small Bowel Obstruction from Capsule Endoscopy

Over the past decade, capsule endoscopy has become the accepted modality for small bowel imaging in the United States. It is very helpful in making the diagnosis of Crohn’s disease; however, this patient population is also at an increased risk of small bowel obstruction secondary to capsule impaction. We present the case of a 60-year-old female with undiagnosed Crohn’s disease who presented to the emergency department with small bowel obstruction after capsule ingestion. She was successfully disimpacted with diatrizoate upper gastrointestinal (GI) series with small bowel follow-through and intravenous steroids. Review of the endoscopic video images revealed findings consistent with Crohn’s disease