Distributed simulation and the grid: Position statements

The Grid provides a new and unrivaled technology for large scale distributed simulation as it enables collaboration and the use of distributed computing resources. This panel paper presents the views of four researchers in the area of Distributed Simulation and the Grid. Together we try to identify the main research issues involved in applying Grid technology to distributed simulation and the key future challenges that need to be solved to achieve this goal. Such challenges include not only technical challenges, but also political ones such as management methodology for the Grid and the development of standards. The benefits of the Grid to end-user simulation modelers also are discussed

Analysis of fouling and breakthrough of process related impurities during depth filtration using confocal microscopy

Titer improvement has driven process intensification in mAb manufacture. However, this has come with the drawback of high cell densities and associated process related impurities such as cell debris, host cell protein (HCP), and DNA. This affects the capacity of depth filters and can lead to carryover of impurities to protein A chromatography leading to early resin fouling. New depth filter materials provide the opportunity to remove more process related impurities at this early stage in the process. Hence, there is a need to understand the mechanism of impurity removal within these filters. In this work, the secondary depth filter Millistak+ X0HC (cellulose and diatomaceous earth) is compared with the X0SP (synthetic), by examining the breakthrough of DNA and HCP. Additionally, a novel method was developed to image the location of key impurities within the depth filter structure under a confocal microscope. Flux, tested at 75, 100, and 250 LMH was found to affect the maximal throughput based on the max pressure of 30 psi, but no significant changes were seen in the HCP and DNA breakthrough. However, a drop in cell culture viability, from 87% to 37%, lead to the DNA breakthrough at 10% decreasing from 81 to 55 L/m2 for X0HC and from 105 to 47 L/m2 for X0SP. The HCP breakthrough was not affected by cell culture viability or filter type. The X0SP filter has a 30%–50% higher max throughput depending on viability, which can be explained by the confocal imaging where the debris and DNA are distributed differently in the layers of the filter pods, with more of the second tighter layer being utilized in the X0SP

Variational collocation for systems of coupled anharmonic oscillators

We have applied a collocation approach to obtain the numerical solution to the stationary Schr\"odinger equation for systems of coupled oscillators. The dependence of the discretized Hamiltonian on scale and angle parameters is exploited to obtain optimal convergence to the exact results. A careful comparison with results taken from the literature is performed, showing the advantages of the present approach.Comment: 14 pages, 10 table

An application of the finite-discrete element method in the simulation of ceramic breakage: methodology for a validation study for alumina specimens

Alumina (aluminum oxide, Al2O3) particles are pelletised and fired to produce high porosity catalyst pellets of complex shapes. These pellets fill cylindrical reactor columns with particulate packing structures that are key to the in-service performance, but will suffer breakages which impact on catalyst performance. The combined Finite- Discrete Element Method (FEMDEM) is ideally suited to the simulation of both the multi-body pellet dynamic packing and quasi-static interactions as well as the stress field of each individual pellet, its deformations and fragmentation. The application of FEMDEM fracture modelling to a fine-grained brittle and porous material is novel. This paper presents a methodology for a validation study through comparison with three point- bending and Brazilian tests and discusses FEMDEMs potential in modelling multi-body fragile systems

Searching for Faint Comoving Companions to the α Centauri system in the VVV Survey Infrared Images

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2017 Crown Copyright. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.The VVV survey has observed the southern disk of the Milky Way in the near infrared, covering 240 deg$^{2}$ in the $ZYJHK_S$ filters. We search the VVV Survey images in a $\sim$19 deg$^{2}$ field around $\alpha$ Centauri, the nearest stellar system to the Sun, to look for possible overlooked companions that the baseline in time of VVV would be able to uncover. The photometric depth of our search reaches $Y\sim$19.3 mag, $J\sim$19 mag, and $K_S\sim$17 mag. This search has yielded no new companions in $\alpha$ Centauri system, setting an upper mass limit for any unseen companion well into the brown dwarf/planetary mass regime. The apparent magnitude limits were turned into effective temperature limits, and the presence of companion objects with effective temperatures warmer than 325K can be ruled out using different state-of-the-art atmospheric models. These limits were transformed into mass limits using evolutionary models, companions with masses above 11 M$_{Jup}$ were discarded, extending the constraints recently provided in the literature up to projected distances of dPeer reviewedFinal Published versio

An application of the finite-discrete element method in the simulation of ceramic breakage: methodology for a validation study for alumina specimens

Alumina (aluminum oxide, Al2O3) particles are pelletised and fired to produce high porosity catalyst pellets of complex shapes. These pellets fill cylindrical reactor columns with particulate packing structures that are key to the in-service performance, but will suffer breakages which impact on catalyst performance. The combined FiniteDiscrete Element Method (FEMDEM) is ideally suited to the simulation of both the multi-body pellet dynamic packing and quasi-static interactions as well as the stress field of each individual pellet, its deformations and fragmentation. The application of FEMDEM fracture modelling to a fine-grained brittle and porous material is novel. This paper presents a methodology for a validation study through comparison with three pointbending and Brazilian tests and discusses FEMDEM's potential in modelling multi-body fragile systems

Feasibility of mHealth technology use among a sample of isolated rural men at high risk for cardiovascular disease

Purpose/Hypothesis: Isolated rural men are considered a health disparities group at high risk for cardiovascular disease. The increasing availability of technologies for self-monitoring for healthy eating, activity and weight loss (ie mHealth) may show promise for engaging rural men in lifestyle modification. This study investigated the feasibility of men from rural isolated areas to use a fitness monitor with text messaging support over a 3- week period. The study examined the men’s daily monitor use for tracking activity and eating, and assessed via written survey, their perspectives about mHealth. Number of Subjects: Twelve men, ages 40 to 69, from a US Department of Agriculture defined isolated rural area, participated. These men were a purposive sample originally recruited to participate in a focus group about their perceptions of the utility of mHealth. The men (50.9 6 8.6 yrs) had a baseline BMI of 25 to 44 kg/m2 (34.8 6 6.6 kg/m2). Eligibility included having cell/smartphones capable of sending/ receiving text messages, access to a computer, willing to use a fitness monitor and have research personnel access the men’s logs. Materials/Methods: Men participated in 2 visits at a community center located within 70 miles of their residence, at baseline and 3 weeks. Assessments included baseline health histories and vital sign biomarkers. The men received training using the fitness monitor with supporting technologies (cell/ smartphone and computer) and were asked to wear the monitor daily for 3 weeks. Men received 1–3 text messages/day for 3 weeks for reminders, education and motivation for self-monitoring. At visit 2, men completed post-intervention surveys about their fitness monitoring. Descriptive data were used for analysis. Results: Men were overweight (n 5 3) or obese (n 5 9) and most (9/12) were hypertensive with only four being treated with medications. One man was hypertensive stage 2 under no treatment and another was pre-hypertensive. Nine of 12 men wore the monitor during all 21 days, two wore it 9 and 15 days respectively and one lost the monitor. Survey data of the 12 men revealed seven checking their step count more than 5 times/day, 6 reported using the associated smart phone app and seven used the optional sleep log feature. Eleven of 12 men manually entered food into the log and most (9/12) did this on $15 days. Ten men indicated the log was helpful in learning about eating; though only 3 indicated it was easy to log food. All men reported reading reminder and motivational text messages sent during the study and 11 plan to continue using the fitness monitor. Conclusions: Men were not well managed for blood pressure or overweight/obesity. Both the log records and the survey results indicated that using fitness monitors was feasible and acceptable among this population. Clinical Relevance: Using mHealth appears feasible as an action-oriented tool for therapists to recommend for lifestyle self-monitoring in isolated rural men. The findings reinforce the important role of therapists in routinely assessing vital signs and making referrals as appropriate

Trichinosis and meat

1 online resource (PDF, 2 pages)This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu

Incorporating prior knowledge improves detection of differences in bacterial growth rate

BACKGROUND: Robust statistical detection of differences in the bacterial growth rate can be challenging, particularly when dealing with small differences or noisy data. The Bayesian approach provides a consistent framework for inferring model parameters and comparing hypotheses. The method captures the full uncertainty of parameter values, whilst making effective use of prior knowledge about a given system to improve estimation. RESULTS: We demonstrated the application of Bayesian analysis to bacterial growth curve comparison. Following extensive testing of the method, the analysis was applied to the large dataset of bacterial responses which are freely available at the web-resource, ComBase. Detection was found to be improved by using prior knowledge from clusters of previously analysed experimental results at similar environmental conditions. A comparison was also made to a more traditional statistical testing method, the F-test, and Bayesian analysis was found to perform more conclusively and to be capable of attributing significance to more subtle differences in growth rate. CONCLUSIONS: We have demonstrated that by making use of existing experimental knowledge, it is possible to significantly improve detection of differences in bacterial growth rate