Application of the Moore rearrangement to the synthesis of 1,4-dioxygenated xanthones and efforts toward the total synthesis of lundurine B

textA novel application of the Moore rearrangement was successfully developed and applied to the synthesis of 1,4-dioxygenated xanthones that would have been difficult to obtain otherwise. The 1,4-dioxygenated xanthone moiety is found in several naturally occurring, biologically active compounds. Several methods by which to obtain the 1,4-dioxygenated xanthone core have been reported; however, high step counts, low yields, and harsh reaction conditions preclude the use of these methods to complex xanthone natural products. Using the Moore rearrangement as a key step in the synthetic sequence has allowed us to prepare several xanthone natural products quickly and more efficiently than what is possible with the prior art. Using the Martin group’s prior experience with the application of ring closing metathesis (RCM) to the field of alkaloid natural product synthesis, the preparation of lundurine B was undertaken. Key features of the proposed synthesis to lundurine B include the formation of a cyclopropane ring by the formation pyrazoline intermediate via [3+2] dipolar cycloaddition followed by dinitrogen extrusion. A second key step in the proposed sequence to lundurine B is a double RCM to form a five- and eight-membered ring in a single operation. While double RCM strategies have been applied to several elegant natural product syntheses, the formation of a five- and eight-membered ring in a single sequence has not been reported. Should the double RCM strategy prove successful for lundurine B, the conditions could in principle be applied to other structurally related natural products.Chemistr

Inverse Spectral Problems for Schr\"odinger-Type Operators with Distributional Matrix-Valued Potentials

The principal purpose of this note is to provide a reconstruction procedure for distributional matrix-valued potential coefficients of Schr\"odinger-type operators on a half-line from the underlying Weyl-Titchmarsh function.Comment: 14 pages. arXiv admin note: text overlap with arXiv:1206.496

Evaluating The Effectiveness Of An Anti-Texting-While-Driving Training Program For Young Drivers: The Role Of Adhd Symptomatology

A long-standing challenge for public health and safety is that motor vehicle crashes (MVCs) are the leading cause of death for U.S. teenagers, a population with disproportionately high crash involvement relative to other road users. Quantitative and qualitative research has identified distracted driving as a significant contributor to young drivers’ overrepresentation in MVCs. This study was designed in the context of this notable public health concern, and the primary goal was to examine psychological factors that are hypothesized, via the Theory of Planned Behavior, to underlie teenage drivers’ decisions to text-while-driving (TWD) with a focus on the influence of ADHD symptoms. The psychological factors of interest were attitudes toward TWD, perceptions of crash risk while TWD, self-perceptions of competence as a driver, and perceptions of task performance. The aims of this project were addressed through a program evaluation of an experiential driver training program designed to educate young novice drivers on the dangers associated with TWD. This program, Turn Off Texting (TOT), was designed and run by the Youth Safety Council of Vermont and the Vermont Department of Motor Vehicles, Safety and Education Unit. Participants included 1203 high school teenagers who participated in 42 TOT program demonstrations across Vermont. The first aim of this study was to examine the influence of ADHD symptoms on psychological factors and behavioral intentions while controlling for and examining the effects of age, gender, and driving experience. ADHD symptoms were associated with more favorable attitudes toward TWD, greater intentions to TWD in the future, and lesser intentions to intervene on a distracted driver in the future. Male gender and increased driving experience also tended to be associated with riskier attitudes, perceptions, and intentions. The second aim of this work was to examine if the psychological factors mediate the associations between ADHD symptoms and the two behavioral intention variables. Results from multiple mediation models showed that only attitudes toward TWD mediated the relations for both intentions to TWD and to intervene in the future. ADHD symptoms continued to have a direct effect on behavioral intentions even when accounting for the indirect effects of the psychological factors; these findings suggest a direct relation of ADHD symptoms and an indirect relation via attitudes. The third and final aim of this study was to investigate the influence of ADHD symptoms, as well as age, gender, and driving experience, on the rate of change in the psychological factors and behavioral intention variables over the course of the TOT program. Findings from two-level regression models showed that the TOT program generally was effective in its goal to produce safer views in regards to the psychological factors and intended behaviors. As hypothesized, ADHD symptoms were associated with less change toward safer attitudes, perceptions of crash risk, and both intentions to TWD and intentions to intervene in the future; the influences of male gender and increased driving experience were similar in their associations with less change toward safer attitudes, perceptions, and intentions. The findings from this study’s three aims have important implications for the development and continued evaluation of specialized driver training programs. Namely, attitudes toward TWD are a viable target for intervention given this factor’s direct and indirect (in the association of ADHD symptoms) effect on intended behavior. Increasing ADHD symptoms and male gender were associated with less change over the course of the program, which represent two areas for more specialized intervention and study

Outlook for detecting the gravitational wave displacement and spin memory effects with current and future gravitational wave detectors

Gravitational wave memory effects arise from non-oscillatory components of gravitational wave signals, and they are predictions of general relativity in the nonlinear regime that have close connections to the asymptotic properties of isolated gravitating systems. There are many types of memory effects that have been studied in the literature. In this paper we focus on the "displacement" and "spin" memories, which are expected to be the largest of these effects from sources such as the binary black hole mergers which have already been detected by LIGO and Virgo. The displacement memory is a change in the relative separation of two initially comoving observers due to a burst of gravitational waves, whereas the spin memory is a portion of the change in relative separation of observers with initial relative velocity. As both of these effects are small, LIGO, Virgo, and KAGRA can only detect memory effects from individual events that are much louder (and thus rarer) than those that have been detected so far. By combining data from multiple events, however, these effects could be detected in a population of binary mergers. In this paper, we present new forecasts for how long current and future detectors will need to operate in order to measure these effects from populations of binary black hole systems that are consistent with the populations inferred from the detections from LIGO and Virgo's first three observing runs. We find that a second-generation detector network of LIGO, Virgo, and KAGRA operating at the O4 ("design") sensitivity for 1.5 years and then operating at the O5 ("plus") sensitivity for an additional 1.5 years can detect the displacement memory. For Cosmic Explorer, we find that displacement memory could be detected for individual loud events, and that the spin memory could be detected in a population after 5 years of observation time.Comment: 18+7 pages, 8 figures; v2: fixed typos and errors and re-ran analysis (results unchanged), matches published versio

Stress Energy tensor in LCFT and the Logarithmic Sugawara construction

We discuss the partners of the stress energy tensor and their structure in Logarithmic conformal field theories. In particular we draw attention to the fundamental differences between theories with zero and non-zero central charge. However they are both characterised by at least two independent parameters. We show how, by using a generalised Sugawara construction, one can calculate the logarithmic partner of T. We show that such a construction works in the c=-2 theory using the conformal dimension one primary currents which generate a logarithmic extension of the Kac-Moody algebra.Comment: 19 pages. Minor correction

The two-boundary Temperley-Lieb algebra

We study a two-boundary extension of the Temperley-Lieb algebra which has recently arisen in statistical mechanics. This algebra lies in a quotient of the affine Hecke algebra of type C and has a natural diagrammatic representation. The algebra has three parameters and, for generic values of these, we determine its representation theory. We use the action of the centre of the affine Hecke algebra to show that all irreducible representations lie within a finite dimensional diagrammatic quotient. These representations are fully characterised by an additional parameter related to the action of the centre. For generic values of this parameter there is a unique representation of dimension 2^N and we show that it is isomorphic to a tensor space representation. We construct a basis in which the Gram matrix is diagonal and use this to discuss the irreducibility of this representation.Comment: 45 pages Latex, 21 eps figures, revised versio