Modal survey of the space shuttle solid rocket motor using multiple input methods

The ability to accurately characterize propellant in a finite element model is a concern of engineers tasked with studying the dynamic response of the Space Shuttle Solid Rocket Motor (SRM). THe uncertainties arising from propellant characterization through specimem testing led to the decision to perform a model survey and model correlation of a single segment of the Shuttle SRM. Multiple input methods were used to excite and define case/propellant modes of both an inert segment and, later, a live propellant segment. These tests were successful at defining highly damped, flexible modes, several pairs of which occured with frequency spacing of less than two percent

A Reanalysis of the Carbon Abundance in the Translucent Cloud toward HD 24534

We have reanalyzed the Goddard High Resolution Spectrograph data set presented by Snow et al. which contains the interstellar intersystem C II] 2325A line through the translucent cloud toward HD 24534 (X Persei). In contrast to the results of Snow et al., we clearly detect the C II] feature at the 3-sigma confidence level and measure a C^+ column density of 2.7 +/- 0.8 x 10^17 cm^-2. Accounting for the C I column density along the line of sight, we find 10^6 C/H = 106 +/- 38 in the interstellar gas toward this star. This gas-phase carbon-to-hydrogen ratio suggests that slightly more carbon depletion may be occurring in translucent as compared to diffuse clouds. The average diffuse-cloud C/H, however, is within the 1-sigma uncertainty of the measurement toward HD 24534. We therefore cannot rule out the possibility that the two cloud types have comparable gas-phase C/H, and therefore comparable depletions of carbon.Comment: 9 pages, 3 figures, to appear in the Astrophysical Journal Letter

Introduction: Celebrating the Mound City Bar Association Centennial: Looking Back, Leading Forward

In 2022, the Mound City Bar Association in St. Louis, one of the first Black bar associations in the country, celebrates its 100th anniversary. In this volume of the Washington University Journal of Law & Policy, distinguished authors look back at a century of contributions of Mound City Bar Association lawyers, judges, and allies, documenting their efforts to eliminate racial discrimination and break down barriers to equal justice. The volume is a testament to the work of countless individuals in the fight for civil rights since the beginning of the association in 1922. The authors also anticipate and examine the challenges ahead and the work yet to be done to achieve equal justice for all in our city, the region, and the country in the years to come

Robust algorithm for detecting floodwater in urban areas using Synthetic Aperture Radar images

Flooding is a major hazard in both rural and urban areas worldwide, but it is in urban areas that the impacts are most severe. High resolution Synthetic Aperture Radar (SAR) sensors are able to detect flood extents in urban areas during both day- and night-time. If obtained in near real-time, these flood extents can be used for emergency flood relief management or as observations for assimilation into flood forecasting models. In this paper a method for detecting flooding in urban areas using near real-time SAR data is developed and extensively tested under a variety of scenarios involving different flood events and different images. The method uses a SAR simulator in conjunction with LiDAR data of the urban area to predict areas of radar shadow and layover in the image caused by buildings and taller vegetation. Of the urban water pixels visible to the SAR, the flood detection accuracy averaged over the test examples was 83%, with a false alarm rate of 9%. The results indicate that flooding can be detected in the urban area to reasonable accuracy, but that this accuracy is limited partly by the SAR’s poor visibility of the urban ground surface due to shadow and layover

Mirror symmetry breaking as a problem in dynamical critical phenomena

The critical properties of the Frank model of spontaneous chiral synthesis are discussed by applying results from the field theoretic renormalization group (RG). The long time and long wavelength features of this microscopic reaction scheme belong to the same universality class as multi-colored directed percolation processes. Thus, the following RG fixed points (FP) govern the critical dynamics of the Frank model for d<4: one unstable FP that corresponds to complete decoupling between the two enantiomers, a saddle-point that corresponds to symmetric interspecies coupling, and two stable FPs that individually correspond to unidirectional couplings between the two chiral molecules. These latter two FPs are associated with the breakdown of mirror or chiral symmetry. In this simplified model of molecular synthesis, homochirality is a natural consequence of the intrinsic reaction noise in the critical regime, which corresponds to extremely dilute chemical systems.Comment: 9 pages, 3 figure

An assessment of chemical contaminants in the marine sediments of southwest Puerto Rico

This report summarizes the results of a characterization of chemical contaminants in the sediments in southwest Puerto Rico. The report is part of a project to integrate various analytical specialties to assess linkages between chemical contaminants and the condition of coral reefs. In this phase of the project, over 120 chemical contaminants were analyzed in sediments collected, including a number of organic (e.g., hydrocarbons), inorganic (e.g., metals), and biological (bacterial) compounds/analytes. The report also provides a preliminary analysis of the association between sediment contaminants and coral species richness. Overall, the levels of chemical contaminants in the study area between Guanica Bay and the town of La Parguera were fairly low. At most of the sites sampled, particularly adjacent to the town of La Parguera, concentrations of organic and inorganic contaminants were below the median values from NOAA’s National Status and Trends Program, which monitors the Nation’s coastal and estuarine waters for chemical contaminants. Elevated levels of a number of contaminant classes were seen at the two sites sampled within Guanica Bay. An initial analysis of modeled PAH (hydrocarbon) data and coral species richness (reef building species) indicated a strong negative correlation between the presence of PAHs in the sediments and coral species richness. Additional work is needed to assess possible reasons for this observed pattern. (PDF contains 126 pages)

Toward Monodisperse Poly(γ-benzyl α,L-glutamate): Uniform, Polar, Molecular Rods

Poly(γ-benzyl α,L-glutamate) (PBLG) has been widely used in studies of the physics of rod-like polymer chains. The helical structure of PBLG gives rise to considerable chain stiffness, such that the persistence length of the chain is on the order of 70 nm in helicogenic solvents. This feature, coupled with the ease of synthesis and good solubility of the polymer has made PBLG the system of choice for the study of both isotropic and liquid crystalline solutions of rod-like macromolecules

Evolving UK policy on diversity in the armed services: multiculturalism and its discontents

Reflecting a generally multiculturalist rhetoric, UK policy in this area has hitherto focussed on enhancing the degree to which the armed services represent or reflect the ethnic makeup of the UK population. Ambitious targets have been set and some progress made in moving towards them. However, the dynamics of population change, together with the diverse preferences of ethno-religious minorities, have meant that the goal of representativeness has remained out of reach. At the same time, the armed services have continued to struggle with an ongoing recruitment problem while the volume of operational commitments has shown little sign of reducing

Engineered Proteins in Materials Research

Peptides and proteins have attracted scientific and technological interest largely because of their intriguing properties as catalysts, receptors, signalling molecules, and therapeutic agents. In attempts to understand and exploit these properties, protein engineering has been used primarily to obtain precious proteins in increased quantities, or to explore systematic alterations in protein sequence through site-directed mutagenesis. Design of protein structures de novo ("from scratch") has attracted less attention, and has been directed in the main toward studies of protein folding (Kamtekar et al., 1993). Such studies represent a key element in the current vigorous investigation of the connections between amino acid sequence and the three-dimensional structures of isolated protein chains in aqueous solution. This chapter describes protein engineering of quite another sort, in which the proteinacious nature of the product is less important than its macromolecular character