Sequential In-core Sorting Performance for a SQL Data Service and for Parallel Sorting on Heterogeneous Clusters

The aim of the paper is to introduce techniques in order to tune sequential in-core sorting algorithms in the frameworks of two applications. The first application is parallel sorting when the processor speeds are not identical in the parallel system. The second application is the Zeta-Data Project (Koskas, 2003) whose aim is to develop novel algorithms for databases issues. About 50 % of the work done in building indexes is devoted to sorting sets of integers. We develop and compare algorithms built to sort with equal keys. Algorithms are variations of the 3way-Quicksort of Segdewick. In order to observe performances and to fully exploit functional units in processors and also in order to optimize the use of the memory system and the different functional units, we use hardware performance counters that are available on most modern microprocessors. We develop also analytical results for one of our algorithms and compare expected results with the measures. For the two applications, we show through fine experiments on an Athlon processor (a three-way superscalar x86 processor), that L1 data cache misses is not the central problem but a subtil proportion of independent retired instructions should be advised to get performance for in-core sorting. Key words: hardware performance counters, in-core sorting algorithms with equal keys, two levels memory hierarchy, optimizing memory accesses, parallelism at the chip level, data structures for databases, parallel sorting. Preprint submitted to Elsevier Science 2 June 2004

A Comprehensive Framework for Comparing Textbooks: Insights from the Literature and Experts

Textbooks are essential components in the learning process. They assist in achieving educational learning outcomes and developing social and cultural values. However, limited studies provide comprehensive frameworks for comparing textbooks. Most have focused on a specific textbook perspective within a particular discipline. Therefore, this study used a triangulation method to develop a comprehensive framework for textbook comparison. Through a systematic literature review and a two-round Fuzzy Delphi method with 155 textbook experts, a textbook comparison framework with four indicators (structure, content, expectations, and language) was developed. Additionally, some of the developed framework indicators and sub-indicators could be relevant for comparing textbooks in a particular discipline. For example, the page count sub-indicator was proven to be useful for comparing humanities and social science textbooks but not natural science textbooks. The findings of this study could facilitate the process of comparing textbooks, hence promoting the understanding of knowledge design and acquisition in different contexts, such as when comparing textbooks from different countries

Hepatitis B and C infection in haemodialysis patients in Libya: prevalence, incidence and risk factors

Background: Patients receiving maintenance haemodialysis (HD) are at higher risk for acquiring Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV) infections than the general population. Strict infection control measures are essential to prevent nosocomial transmission. We aimed to investigate the incidence and prevalence of HBV and HCV infection in the HD population of Libya as well as risk factors for infection. Methods: All adult patients receiving maintenance HD (n=2382) in Libyan dialysis centres (n=39) were studied between May 2009 and October 2010. Testing for Hepatitis B surface antigen (HBsAg) and anti-HCV antibodies was performed at initiation of dialysis and every 3–6 months thereafter. Patients who were sero-negative for HBV and HCV (n=1160) were followed up for 1 year to detect sero-conversions. Results: Participant median age was 49 years and 58% were male. 831 patients (34.9%) were sero-positive for HBV and/or HCV (anti-HCV positive 31.1%; HBsAg positive 2.6%; both positive 1.2%). Of the sero-positive patients 4.7% were known to be infected before the initiation of HD. The prevalence of HBV±HCV infection varied widely between HD centres from 0% to 75.9%. Sero-positive patients were younger, had longer time on dialysis and more previous blood transfusions. Prospective follow-up revealed an incidence of sero-conversion of 7.7% during 1 year (7.1% HCV; 0.6% HBV). Wide variation in rates of newly acquired infections was observed between dialysis centres. All new HBV cases were referred from centres already treating HBV infected patients. New HCV infections were reported in most centres but the rate of HCV sero-conversion varied widely from 1.5% to 31%. Duration of dialysis, history of previous renal transplant and history of receiving HD in another centre in Libya were significantly associated with sero-conversion. Conclusion: Patients on maintenance HD in Libya have a high incidence and prevalence of HCV infection and lower rates of HBV infection. The factors associated with HBV and HCV infection are highly suggestive of nosocomial transmission within HD units. Urgent action is required to improve infection control measures in HD centres and to reduce dependence on blood transfusions for the treatment of anaemia. Keywords: Haemodialysis, Hepatitis B, Hepatitis C, Incidence, Libya, Nosocomial infection, Prevalenc

Novel compact bed design for adsorption cooling systems: Parametric numerical study

A new bed configuration consists of two layers of packed beads separated by vapor passage is simulated using transient three-dimensional local thermal non-equilibrium model (LTNE). Darcy–Brinkman equation is solved in both the porous layers and the vapor passage. Silica-gel/water is selected as a working pair. Heat and mass diffusion time are calculated from the scaling analysis of the governing equations. Results show that reducing particle diameter and adsorbent bed thickness while enhancing the bed thermal conductivity can lead to a dramatic improvement in specific cooling power (SCP). Also, the feeding vapor passage is needed for particle size smaller than 0.5 mm but it can be removed for bigger particles. Analysis of results indicates that the adsorption process is controlled by heat diffusion resistance when heat diffusion time to mass diffusion time ratio (tth/tm)~O(100) or more. While the adsorption is controlled by mass diffusion resistance when (tth/tm)~O(1) or less