Educating Lawyers: Preparation for the Profession of Law

Examines the unique aspects and limitations of legal education, as part of a series of reports from the foundation's Preparation for the Professions Program

Anomalous increase in nematic-isotropic transition temperature in dimer molecules induced by magnetic field

We have determined the nematic-isotropic transition temperature as a function of applied magnetic field in three different thermotropic liquid crystalline dimers. These molecules are comprised of two rigid calamitic moieties joined end to end by flexible spacers with odd numbers of methylene groups. They show an unprecedented magnetic field enhancement of nematic order in that the transition temperature is increased by up to 15K when subjected to 22T magnetic field. The increase is conjectured to be caused by a magnetic field-induced decrease of the average bend angle in the aliphatic spacers connecting the rigid mesogenic units of the dimers

Influence of supercoiling on the disruption of dsDNA

We propose that supercoiling energizes double-stranded DNA (dsDNA) so as to facilitate thermal fluctuations to an unzipped state. We support this with a model of two elastic rods coupled via forces that represent base pair interactions. Supercoiling is shown to lead to a spatially localized higher energy state in a small region of dsDNA consisting of a few base pairs. This causes the distance between specific base pairs to be extended, enhancing the thermal probability for their disruption. Our theory permits the development of an analogy between this unzipping transition and a second order phase transition, for which the possibility of a new set of critical exponents is identified

Beat Cepheid Period Ratios from OPAL Opacities

The discovery of a large number of beat Cepheids in the Large Magellanic Cloud in the MACHO survey, provides an opportunity to compare the characteristics of such Cepheids over a range of metallicities. We produced a large grid of linear nonadiabatic pulsation models using the OPAL opacity tables and with compositions corresponding to those of the Milky Way, and the Large and Small Magellanic Clouds. Using the relationship between the period ratio and the main pulsation period, we are able to define a range of models which correspond to the observed beat Cepheids, and thereby constrain the physical characteristics of the LMC beat Cepheids. We are also able to make some predictions about the nature of the yet-to-be-discovered SMC beat Cepheids.Comment: 20 pages, 6 embedded Postscript figures, uses aasms4.sty. Accepted for publication in the 1997 September A

Articulating Axial-Flow Turbomachinery Rotor Blade For Enabling Variable Speed Gas Turbine Engine

Current technology gas turbine engines are generally optimized to operate at nearly a fixed speed with fixed blade geometries for the design operating condition. When the operating condition of the engine changes, the flow incidence angles may not be optimum with the blade geometries resulting in reduced off-design performance. But, if we have the capability of articulating the pitch angle of axial-flow compressor/turbine blades in coordination with adjustable stator vanes, it can improve performance by maintaining flow incidence angles within the optimum range for given blade geometries at all operating conditions. Maintaining flow incidence angles within the optimum range can prevent the likelihood of flow separation in the blade passage and also reduce the thermal stresses developed due to aerothermal loads for variable speed gas turbine applications. This paper discusses a recent invention of adaptable articulating axial-flow compressor or turbine rotor blade that can significantly impact developing a high efficiency variable speed gas turbine for rotorcraft or ground vehicles that may need to operate optimally at different torque/speed conditions during various maneuvers. U.S. Army Research Laboratory has partnered with University of California San Diego and Iowa State University Collaborators to conduct high fidelity stator-rotor interaction analysis for evaluating the aerodynamic efficiency benefits of an articulating axial flow turbine blade concept. In addition, a design study for articulating turbine or compressor rotor blade using smart material based actuators using Shape Memory Alloy (SMA) has been carried out. Highly coupled fluid-structure interaction computational study of articulating turbine rotor and stator blades, together with a design concept of articulating axial-flow turbomachinery rotor blade using a smart material such as SMA is presented

Knowledge and Awareness Among Patients with Chronic Kidney Disease Stage 3

Knowledge is a prerequisite for changing behavior, and is useful for improving outcomes and reducing mortality rates in patients diagnosed with chronic kidney disease (CKD). The purpose of this article is to describe baseline CKD knowledge and awareness obtained as part of a larger study testing the feasibility of a self-management intervention. Thirty patients were recruited who had CKD Stage 3 with coexisting diabetes and hypertension. Fifty-four percent of the sample were unaware of their CKD diagnosis. Participants had a moderate amount of CKD knowledge. This study suggests the need to increase knowledge in patients with CKD Stage 3 to aid in slowing disease progression

The case for Mars: Concept development for a Mars research station

A program to establish a permanent scientific research base on Mars is described. A Mars base as the much needed long-term focus for the space program is presented. A permanent base was chosen rather than the more conventional concept of a series of individual missions to different sites because the permanent base offers much greater scientific return plus greater crew safety and the potential for eventual growth into a settlement. The Mars base will strive for self-sufficiency and autonomy from Earth. Martian resources will be used to provide life support materials and consumables. The Martian atmosphere will provide a convenient source of volatiles: CO2, N2, and water. Rocket propellant (for returning vehicles), fuels, breathable air, and fertilizers will be manufactured from Mars air. Food will be grown on Mars using Martian materials as plant nutrients. A permanent human presence will be maintained on Mars beginning with the first manned landing via a strategy of crew overlap. This permanent presence will ensure safety and reliability of systems through continuous tending, maintenance, and expansion of the base's equipment and systems. A permanent base will allow the development of a substantial facility on Mars for the same cost (in terms of Earth departure mass) as a series of temporary camps. A base equipped with surface rovers, airplanes, and the ability to manufacture consumables and return propellant will allow far more extensive planetary exploration over a given period of years than would approaches featuring a series of short exploration missions such as the Apollo Moon program

On the Interpretation of Supernova Light Echo Profiles and Spectra

The light echo systems of historical supernovae in the Milky Way and local group galaxies provide an unprecedented opportunity to reveal the effects of asymmetry on observables, particularly optical spectra. Scattering dust at different locations on the light echo ellipsoid witnesses the supernova from different perspectives and the light consequently scattered towards Earth preserves the shape of line profile variations introduced by asymmetries in the supernova photosphere. However, the interpretation of supernova light echo spectra to date has not involved a detailed consideration of the effects of outburst duration and geometrical scattering modifications due to finite scattering dust filament dimension, inclination, and image point-spread function and spectrograph slit width. In this paper, we explore the implications of these factors and present a framework for future resolved supernova light echo spectra interpretation, and test it against Cas A and SN 1987A light echo spectra. We conclude that the full modeling of the dimensions and orientation of the scattering dust using the observed light echoes at two or more epochs is critical for the correct interpretation of light echo spectra. Indeed, without doing so one might falsely conclude that differences exist when none are actually present.Comment: 18 pages, 22 figures, accepted for publication in Ap

Bioresorbable Film for the Prevention of Adhesion to the Anterior Spine After Anterolateral Discectomy

Background context The development of scar tissue and adhesions postoperatively is a natural consequence of healing but can be associated with medical complications and render reoperation difficult. Many biocompatible products have been evaluated as barriers or deterrents to adhesions. Purpose To evaluate the efficacy of a bioresorbable polylactide film as a barrier to adhesion formation after anterolateral discectomy. Study design Experimental study. Methods Seven, skeletally mature female sheep underwent a retroperitoneal approach to the anterolateral lumbar spine. A discectomy was performed at two levels with an intervening unoperated disc site. One site was treated with a polylactide film barrier (Hydrosorb Shield; MacroPore Biosurgery, San Diego, CA) affixed with tacks manufactured from the same material. The second site was left untreated. Treatment and control sites were randomly assigned. Postmortem analysis included scar tenacity scoring on five spines and histological evaluation on two spines. Results The application of the Hydrosorb film barrier allowed a definite dissection plane during scar tenacity scoring and there was a significant difference in the development of adhesions to the disc between the control and treated sites. Histological evaluation revealed evidence of barrier formation to scar tissue and no significant adverse inflammatory reactions. Conclusions Hydrosorb Shield appears to be an effective postoperative barrier to scar tissue adhesion after anterolateral discectomy. The use of polylactide tacks was beneficial to affix the barrier film in place. Safety issues associated with delayed healing or adverse response to the film or tacks were not observed. Hydrosorb film may be useful as an antiadhesion barrier facilitating dissection during surgical revision in anterior approaches to the spine. Further studies are indicated to evaluate the performance of the bioresorbable material as an antiadhesion barrier in techniques of spinal fusion and disc replacement

Second harmonic light scattering induced by defects in the twist-bend nematic phase of liquid crystal dimers

The nematic twist-bend (NTB) phase, exhibited by certain thermotropic liquid crystalline (LC) dimers, represents a new orientationally ordered mesophase -- the first distinct nematic variant discovered in many years. The NTB phase is distinguished by a heliconical winding of the average molecular long axis (director) with a remarkably short (nanoscale) pitch and, in systems of achiral dimers, with an equal probability to form right- and left-handed domains. The NTB structure thus provides another fascinating example of spontaneous chiral symmetry breaking in nature. The order parameter driving the formation of the heliconical state has been theoretically conjectured to be a polarization field, deriving from the bent conformation of the dimers, that rotates helically with the same nanoscale pitch as the director field. It therefore presents a significant challenge for experimental detection. Here we report a second harmonic light scattering (SHLS) study on two achiral, NTB-forming LCs, which is sensitive to the polarization field due to micron-scale distortion of the helical structure associated with naturally-occurring textural defects. These defects are parabolic focal conics of smectic-like ``pseudo-layers", defined by planes of equivalent phase in a coarse-grained description of the NTB state. Our SHLS data are explained by a coarse-grained free energy density that combines a Landau-deGennes expansion of the polarization field, the elastic energy of a nematic, and a linear coupling between the two