Contributions to the mixed-alkali effect in molecular dynamics simulations of alkali silicate glasses

The mixed-alkali effect on the cation dynamics in silicate glasses is analyzed via molecular dynamics simulations. Observations suggest a description of the dynamics in terms of stable sites mostly specific to one ionic species. As main contributions to the mixed--alkali slowdown longer residence times and an increased probability of correlated backjumps are identified. The slowdown is related to the limited accessibility of foreign sites. The mismatch experienced in a foreign site is stronger and more retarding for the larger ions, the smaller ions can be temporarily accommodated. Also correlations between unlike as well as like cations are demonstrated that support cooperative behavior.Comment: 10 pages, 12 figures, 1 table, revtex4, submitted to Phys. Rev.

Bald Eagles at the Savanna Army Depot

Eagle Valley Environmentalists Technical Report #SADE-81, Research Report conducted December 1980 - March 1981, under a contract with the United States Arm

Definition of smolder experiments for Spacelab

The feasibility of conducting experiments in space on smoldering combustion was studied to conceptually design specific smoldering experiments to be conducted in the Shuttle/Spacelab System. Design information for identified experiment critical components is provided. The analytical and experimental basis for conducting research on smoldering phenomena in space was established. Physical descriptions of the various competing processes pertaining to smoldering combustion were identified. The need for space research was defined based on limitations of existing knowledge and limitations of ground-based reduced-gravity experimental facilities

Realizing the Dream: African American Males’ Narratives that Encouraged the Pursuit of Doctoral Education

This article used personal narratives to discover factors affecting the decision of African American males to consider doctoral education. This study was based on qualitative interviews with 18 African American male doctoral students enrolled at predominantly white institutions as they reflected on their reasons for pursuing an advanced degree. The following were found to influence their decision: (a) need for faculty encouragement, (b) motivation to pursue a doctorate, and (c) their personal motivations. Recommendations are offered for increasing the numbers of African American male doctoral students

Investigation of the Role of Acetabular Soft Tissue in the Joint Biomechanics of the Hip

Osteoarthritis causes more than 250,000 hip replacements annually. Hip replacements and other treatments for hip injury cost the United States healthcare system $4 billion each year. Arthritis of the hip joint is typically evaluated via arthroscopy, a minimally invasive endoscopic procedure that involves insertion of a camera and other surgical tools into the joint. This procedure allows direct inspection of the soft tissues of the hip, but requires damage to the joint capsule via a surgical incision (capsulotomy). Repair of the capsulotomy is performed on a case by case basis, with 80% of surgeons routinely leaving the incision unrepaired. The effects of this capsular damage on joint stability are not fully understood, and it is hypothesized that this damage could lead to accelerated deterioration of the joint later in a patient’s life. A cadaveric study has been designed to investigate the consequences of capsular damage on the stability of the hip via evaluation of the joint suction seal. A mechanical loading system will be used to break the suction seal within the joint with varying degrees of damage to the joint soft tissue. The load required to break the suction seal for each of these conditions will be recorded and evaluated to demonstrate the role of the hip capsule in the formation of the suction seal of the hip joint

CRITICAL ECONOMIC FACTORS FOR SUCCESS OF A BIOMASS CONVERSION PLANT FOR AGRICULTURAL RESIDUE, YARD RESIDUE AND WOOD WASTE IN FLORIDA

This model evaluates the potential success of a cellulosic ethanol plant in Florida. Critical Economic factors of the plant were simulated to assess the ability of this project. These critical factors include the feedstock to be used, the cost of the facility, transportation costs and the discount rate for the net present value (NPV). Results and observations are presented in this paper.Biofuels, renewable energy, cellulosic ethanol, biomass, Agribusiness, Community/Rural/Urban Development, Crop Production/Industries, Financial Economics, Production Economics, Productivity Analysis, Resource /Energy Economics and Policy, Risk and Uncertainty,

Internal Friction and Vulnerability of Mixed Alkali Glasses

Based on a hopping model we show how the mixed alkali effect in glasses can be understood if only a small fraction c_V ofthe available sites for the mobile ions is vacant. In particular, we reproduce the peculiar behavior of the internal friction and the steep fall (''vulnerability'') of the mobility of the majority ion upon small replacements by the minority ion. The single and mixed alkali internal friction peaks are caused by ion-vacancy and ion-ion exchange processes. If c_V is small, they can become comparable in height even at small mixing ratios. The large vulnerability is explained by a trapping of vacancies induced by the minority ions. Reasonable choices of model parameters yield typical behaviors found in experiments.Comment: 4 pages, 4 figure

Processing and Linking Audio Events in Large Multimedia Archives: The EU inEvent Project

In the inEvent EU project [1], we aim at structuring, retrieving, and sharing large archives of networked, and dynamically changing, multimedia recordings, mainly consisting of meetings, videoconferences, and lectures. More specifically, we are developing an integrated system that performs audiovisual processing of multimedia recordings, and labels them in terms of interconnected “hyper-events ” (a notion inspired from hyper-texts). Each hyper-event is composed of simpler facets, including audio-video recordings and metadata, which are then easier to search, retrieve and share. In the present paper, we mainly cover the audio processing aspects of the system, including speech recognition, speaker diarization and linking (across recordings), the use of these features for hyper-event indexing and recommendation, and the search portal. We present initial results for feature extraction from lecture recordings using the TED talks. Index Terms: Networked multimedia events; audio processing: speech recognition; speaker diarization and linking; multimedia indexing and searching; hyper-events. 1

Group-based pharmacogenetic prediction: is it feasible and do current NHS England ethnic classifications provide appropriate data?

Inter-individual variation of drug metabolising enzymes (DMEs) leads to variable efficacy of many drugs and even adverse drug responses. Consequently, it would be desirable to test variants of many DMEs before drug treatment. Inter-ethnic differences in frequency mean that the choice of SNPs to test may vary across population groups. Here we examine the utility of testing representative groups as a way of assessing what variants might be tested. We show that publicly available population information is potentially useful for determining loci for pre-treatment genetic testing, and for determining the most prevalent risk haplotypes in defined groups. However, we also show that the NHS England classifications have limitations for grouping for these purposes, in particular for people of African descent. We conclude: (1) genotyping of hospital patients and people from the hospital catchment area confers no advantage over using samples from appropriate existing ethnic group collections or publicly available data, (2) given the current NHS England Black African grouping, a decision as to whether to test, would have to apply to all patients of recent Black African ancestry to cover reported risk alleles and (3) the current scarcity of available genome and drug effect data from Africans is a problem for both testing and treatment decisions

Matrix controlled channel diffusion of sodium in amorphous silica

To find the origin of the diffusion channels observed in sodium-silicate glasses, we have performed classical molecular dynamics simulations of Na$_2$O--4SiO$_2$ during which the mass of the Si and O atoms has been multiplied by a tuning coefficient. We observe that the channels disappear and that the diffusive motion of the sodium atoms vanishes if this coefficient is larger than a threshold value. Above this threshold the vibrational states of the matrix are not compatible with those of the sodium ions. We interpret hence the decrease of the diffusion by the absence of resonance conditions.Comment: 5 pages, 4 figure