A "fast growth" method of computing free energy differences

Let Delta F be the free energy difference between two equilibrium states of a system. An established method of numerically computing Delta F involves a single, long ``switching simulation'', during which the system is driven reversibly from one state to the other (slow growth, or adiabatic switching). Here we study a method of obtaining the same result from numerous independent, irreversible simulations of much shorter duration (fast growth). We illustrate the fast growth method, computing the excess chemical potential of a Lennard-Jones fluid as a test case, and we examine the performance of fast growth as a practical computational tool.Comment: 17 pages + 4 figures, accepted for publication in J.Chem.Phy

Role of school counselors in deterring juvenile delinquency: a Mississippi pilot study

Throughout the world juvenile crime remains a major part of the criminal justice system. Although crime has been on the downward trend for the past decade there is still much research that has been done is this area and is on-going. Most research that has been done in this area has solely looked at the juveniles searching for reasons as to why they commit crime. This research looked at a different aspect of juvenile crime. School counselors have a direct role in shaping a youth’s future life and have influences that others may not have. This qualitative research referenced two leading theories social control theory and social learning theory. The research shothat counselors were in unique positions to deter at-risk and/or delinquent behavior in students how they make those connections and the resources available to them as well as what resources they need

Directional solidification of flake and nodular cast iron during KC-135 low-g maneuvers

Alloys solidified in a low-gravity environment can, due to the elimination of sedimentation and convection, form unique and often desirable microstructures. One method of studying the effects of low-gravity (low-g) on alloy solidification was the use of the NASA KC-135 aircraft flying repetitive low-g maneuvers. Each maneuver gives from 20 to 30 seconds of low-g which is between about 0.1 and 0.001 gravity. A directional solidification furnace was used to study the behavior of off eutectic composition case irons in a low-g environment. The solidification interface of hypereutectic flake and spheroidal graphite case irons was slowly advanced through a rod sample, 5 mm in diameter. Controlled solidification was continued through a number of aircraft parabolas. The known solidification rate of the sample was then correlated with accelerometer data to determine the gravity level during solidification for any location of the sample. The thermal gradient and solidification rate were controlled independently. Samples run on the KC-135 aircraft exhibited bands of coarser graphite or of larger nodules usually corresponding to the regions solidified under low-g. Samples containing high phosphorous (used in order to determine the eutectic cell) exhibited larger eutectic cells in the low-g zone, followed by a band of coarser graphite

Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) is a chronic and often disabling condition that is seen in many patients seeking pain management. The condition leaves patients in excruciating pain that is disproportionate to the inciting injury. In addition, patients with this pain disorder experience abnormal sensations such as cold and heat allodynia, hyperalgesia, edema, abnormal sudomotor activity and trophic changes (D. Lee et al., 2015). CRPS disproportionally affects four times as many women as men (Alexander, Peterlin, Perreault, Grothusen, & Schwartzman, 2012). There are two types of CRPS: type 1, often referred to as reflex sympathetic dystrophy (RSD), is not evident of nerve damage while type 2 does indicate nerve damage. The pathophysiology of CRPS remains unproven: however, many hypotheses exist due to this disorder’s multiple system dysfunction and the evidence is continuing to progress. As the pathophysiologic mechanisms of CRPS further advance, treatment modalities will continue to emerge in order for health care providers to improve the outcomes for patients suffering from CRPS

Asymmetric synthesis of arylglycines, The

1992 Summer.Includes bibliographical references.The asymmetric synthesis of several arylglycines is discussed. Several methods for the coupling of an aromatic group to the chiral bromoglycinates (171, 172) were developed. It was found that the cuprate and Friedel-Crafts couplings provided the desired aryl-coupled glycinates in the greatest yield with excellent selectivity. An oxidative protocol was employed to unmask the oxazinone chiral auxiliary which provided the desired free α-amino acids. A reductive deprotection method was also employed in two unique cases which efficiently gave the arylglycine products. The % ee's ranged from 82 to 94 %. This methodology was further utilized in an approach to the asymmetric synthesis of the bis-arylglycine, actinoidic acid. This study explored the scope of the Stille biphenyl cross-coupling reaction and produced methodology for the synthesis of biphenyl amino acid precursors

Preliminary science report on the directional solidification of hypereutectic cast iron during KC-135 low-G maneuvers

An ADSS-P directional solidification furnace was reconfigured for operation on the KC-135 low-g aircraft. The system offers many advantages over quench ingot methods for study of the effects of sedimentation and convection on alloy formation. The directional sodification furnace system was first flown during the September 1982 series of flights. The microstructure of the hypereutectic cast iron sample solidified on one of these flights suggests a low-g effect on graphite morphology. Further experiments are needed to ascertain that this effect is due to low-gravity and to deduce which of the possible mechanisms is responsible for it

Exosomes released from breast cancer carcinomas stimulate cell movement

For metastasis to occur cells must communicate with to their local environment to initiate growth and invasion. Exosomes have emerged as an important mediator of cell-to-cell signalling through the transfer of molecules such as mRNAs, microRNAs, and proteins between cells. Exosomes have been proposed to act as regulators of cancer progression. Here, we study the effect of exosomes on cell migration, an important step in metastasis. We performed cell migration assays, endocytosis assays, and exosome proteomic profiling on exosomes released from three breast cancer cell lines that model progressive stages of metastasis. Results from these experiments suggest: (1) exosomes promote cell migration and (2) the signal is stronger from exosomes isolated from cells with higher metastatic potentials; (3) exosomes are endocytosed at the same rate regardless of the cell type; (4) exosomes released from cells show differential enrichment of proteins with unique protein signatures of both identity and abundance. We conclude that breast cancer cells of increasing metastatic potential secrete exosomes with distinct protein signatures that proportionally increase cell movement and suggest that released exosomes could play an active role in metastasis

Opportunities, barriers, and recommendations in down syndrome research

BACKGROUND: Recent advances in medical care have increased life expectancy and improved the quality of life for people with Down syndrome (DS). These advances are the result of both pre-clinical and clinical research but much about DS is still poorly understood. In 2020, the NIH announced their plan to update their DS research plan and requested input from the scientific and advocacy community. OBJECTIVE: The National Down Syndrome Society (NDSS) and the LuMind IDSC Foundation worked together with scientific and medical experts to develop recommendations for the NIH research plan. METHODS: NDSS and LuMind IDSC assembled over 50 experts across multiple disciplines and organized them in eleven working groups focused on specific issues for people with DS. RESULTS: This review article summarizes the research gaps and recommendations that have the potential to improve the health and quality of life for people with DS within the next decade. CONCLUSIONS: This review highlights many of the scientific gaps that exist in DS research. Based on these gaps, a multidisciplinary group of DS experts has made recommendations to advance DS research. This paper may also aid policymakers and the DS community to build a comprehensive national DS research strategy