Introducing Parallelism to First-Year CS Majors

We propose to strengthen the computer science (CS) curriculum by embedding parallel concepts in a required first-semester seminar taken by all incoming declared CS majors. We introduce students to parallel computing concepts through a series of unplugged activities so that students see parallel approaches as a natural form of solution to a task. We describe a pilot offering of the class and activities, with measurements and analysis of what students self-report and their performance on assessments

Numerical and Experimental Analysis of the Daughter Distribution in Liquid-Liquid Stirred Tanks

The drop size distributions (DSDs) of a dilute immiscible liquid-liquid mixture were measured in a fully turbulent stirred tank operating at different impeller speeds. The results were used to infer the best daughter distribution function (DDF) leading to the best reproduction of the shape of the DSD. Bell-shaped, U-shaped, M-shaped, and uniform statistical DDFs were studied, producing from two to four daughters from each breakup event. A simplified approach from the literature was adopted to solve the population balance equation that considers the spectrum of the turbulence inside the tank obtained from computational fluid dynamics simulations. The U-shaped distribution producing four fragments better reproduces the shape of the experimental DSD in the studied system

Incidence and Outcome of Invasive Fungal Diseases after Allogeneic Stem Cell Transplantation: A Prospective Study of the Gruppo Italiano Trapianto Midollo Osseo (GITMO).

AbstractEpidemiologic investigation of invasive fungal diseases (IFDs) in allogeneic hematopoietic stem cell transplantation (allo-HSCT) may be useful to identify subpopulations who might benefit from targeted treatment strategies. The Gruppo Italiano Trapianto Midollo Osseo (GITMO) prospectively registered data on 1858 consecutive patients undergoing allo-HSCT between 2008 and 2010. Logistic regression analysis was performed to identify risk factors for proven/probable IFD (PP-IFD) during the early (days 0 to 40), late (days 41 to 100), and very late (days 101 to 365) phases after allo-HSCT and to evaluate the impact of PP-IFDs on 1-year overall survival. The cumulative incidence of PP-IFDs was 5.1% at 40 days, 6.7% at 100 days, and 8.8% at 12 months post-transplantation. Multivariate analysis identified the following variables as associated with PP-IFDs: transplant from an unrelated volunteer donor or cord blood, active acute leukemia at the time of transplantation, and an IFD before transplantation in the early phase; transplant from an unrelated volunteer donor or cord blood and grade II-IV acute graft-versus-host disease (GVHD) in the late phase; and grade II-IV acute GVHD and extensive chronic GVHD in the very late phase. The risk for PP-IFD was significantly higher when acute GVHD was followed by chronic GVHD and when acute GVHD occurred in patients undergoing transplantation with grafts from other than matched related donors. The presence of PP-IFD was an independent factor in long-term survival (hazard ratio, 2.90; 95% confidence interval, 2.32 to 3.62; P < .0001). Our findings indicate that tailored prevention strategies may be useful in subpopulations at differing levels of risk for PP-IFDs

IT-supported integrated care pathways for diabetes: A compilation and review of good practices

Introduction: Integrated Care Pathways (ICPs) are a method for the mutual decision-making and organization of care for a well-defined group of patients during a well-defined period. The aim of a care pathway is to enhance the quality of care by improving patient outcomes, promoting patient safety, increasing patient satisfaction, and optimizing the use of resources. To describe this concept, different names are used, e.g. care pathways and integrated care pathways. Modern information technologies (IT) can support ICPs by enabling patient empowerment, better management, and the monitoring of care provided by multidisciplinary teams. This study analyses ICPs across Europe, identifying commonalities and success factors to establish good practices for IT-supported ICPs in diabetes care. Methods: A mixed-method approach was applied, combining desk research on 24 projects from the European Innovation Partnership on Active and Healthy Ageing (EIP on AHA) with follow-up interviews of project participants, and a non-systematic literature review. We applied a Delphi technique to select process and outcome indicators, derived from different literature sources which were compiled and applied for the identification of successful good practices. Results: Desk research identified sixteen projects featuring IT-supported ICPs, mostly derived from the EIP on AHA, as good practices based on our criteria. Follow-up interviews were then conducted with representatives from 9 of the 16 projects to gather information not publicly available and understand how these projects were meeting the identified criteria. In parallel, the non-systematic literature review of 434 PubMed search results revealed a total of eight relevant projects. On the basis of the selected EIP on AHA project data and non-systematic literature review, no commonalities with regard to defined process or outcome indicators could be identified through our approach. Conversely, the research produced a heterogeneous picture in all aspects of the projects’ indicators. Data from desk research and follow-up interviews partly lacked information on outcome and performance, which limited the comparison between practices. Conclusion: Applying a comprehensive set of indicators in a multi-method approach to assess the projects included in this research study did not reveal any obvious commonalities which might serve as a blueprint for future IT-supported ICP projects. Instead, an unexpected high degree of heterogeneity was observed, that may reflect diverse local implementation requirements e.g. specificities of the local healthcare system, local regulations, or preexisting structures used for the project setup. Improving the definition of and reporting on project outcomes could help advance research on and implementation of effective integrated care solutions for chronic disease management across Europe

Dispersion coefficients and settling velocities of solids in slurry vessels stirred with different types of multiple impellers

Equipment dealing with stirred suspensions are broadly used in the process industry. Out of the various aspects affecting their performance, solids distribution is addressed in this paper. The behaviour of a tank of high aspect ratio stirred with multiple impellers of three types is analysed. The purpose is to acquire fundamental information on parameters useful for their description, namely the axial dispersion coefficient of the solids phase and the particle settling velocity. Both transient and steady-state experiments were performed with a variety of dilute suspensions. The data were analysed with the axial sedimentation-dispersion model. The axial dispersion coefficient of the solid phase was found to differ from that of the liquid by less than 15% for all the impellers and conditions tested. The effective particle settling velocity in the stirred medium was then determined. As happens in equipment stirred with multiple radial turbines, the value of this parameter was found to be different, in general, from the terminal settling velocity. It is shown that a correlation among these parameters and Kolmogoroff length microscale and particle size obtained previously for a specific geometric configuration is actually independent of the impeller type

Gas-liquid flow and bubble size distribution in stirred tanks

This work is aimed at investigating the turbulent two-phase flow and the bubble size distribution (BSD) in aerated stirred tanks by experiments and Computational Fluid Dynamics (CFD) modelling. The experimental data were collected using a two-phase Particle Image Velocimetry technique and a Digital Image Processing method based on a threshold criterion. With the former technique, the liquid and the gas phase ensemble-averaged mean and r.m.s. velocities are measured simultaneously, while with the latter the dimensions of the bubbles dispersed inside the liquid are evaluated. On the modelling side, a CFD approach, based on the solution of Reynolds Average Navier-Stokes equations in an Eulerian framework for both phases, is adopted. As for the bubble dimensions modelling, besides the mono-dispersed assumption, a population balance method, named MUSIG, with bubble break-up and coalescence models is considered. The BSD and the axial and radial velocity of the gas and the liquid phase are presented and discussed. The outcome of the computational work are evaluated on the basis of the experimental results

Role of CFD techniques in discriminating experimental solids concentration data in stirred suspensions and modelling of the solids concentration profiles in a pilot reactor

In this work, the suitability of an optical probe for studying local solid particle distribution in agitated systems and of Computational Fluid Dynamics (CFD) as a means to discriminate among the experimental data is investigated. Solids concentrations are determined in a high-aspect-ratio baffled tank stirred with three Rushton turbines by means of a fibre-optical probe and by CFD simulations. The local analysis of the simulated liquid flow field allows to better understand the source of differences in the measured solid concentrations that are obtained by changing the angular orientation of the probe in a few specific positions and, therefore, to identify the best operating mode for the measurements. The predicted radial and axial solid concentration profiles are then compared with the experimental data obtained with the most reliable probe orientation and very good agreement is found. This study allows to point out that, once proper computational strategies are selected, the usefulness of CFD simulations is twofold: they can be adopted for obtaining reliable predictions of various parameters in solid-liquid systems and used for gaining a better understanding of the complex fluid flow features of turbulent multiphase flows

Bubble size distribution and turbulent two-phase flow in aerated stirred vessels

This work concerns an experimental and computational investigation of the turbulent two-phase flow and bubble size distribution in a gas-liquid stirred vessel of standard geometry. The experiments were carried out using a two-phase Particle Image Velocimetry technique and a digital image processing method based on a threshold criterion. With the former technique, the liquid and the gas phase ensemble-averaged mean and r.m.s. velocities were measured simultaneously, while with the latter the dimensions of the bubbles dispersed inside the liquid were evaluated. On the modelling side, a Computational Fluid Dynamic approach was adopted, that was based on the solution of Reynolds Average Navier-Stokes equations in an Eulerian framework for both phases. As for the bubble dimensions modelling, the mono-disperse assumption as well as the Multiple Size Group Model, including a population balance with break-up and coalescence models, were considered. The bubble size distribution and the axial and radial velocity of the gas and the liquid phase measured on a vertical plane mid-way between two baffles are presented and discussed. The outcomes of the computational work are evaluated on the basis of the experimental finding