Algorithms For Static Task Assignment And Symmetric Contraction In Distributed Computing Systems

14 pagesIn this paper, we look at the mapping problem, which was posed within the domain of parallel processing, and we redefine that problem for use in distributed computing systems whose underlying communication medium is a broadcast medium such as ethernet. We describe an efficient algorithm which can be utilized to find optimal assignments of tasks to processors for a wide variety of distributed algorithms when symmetric contraction of the algorithm is necessary. 'Ne also describe a heuristic algorithm for use in finding suboptimal assignments of tasks to processors for arbitrary distributed computations. Both algorithms model the mapping problem as the Graph Partitioning Problem. Our algorithms utilize an efficient algorithm for finding maximum weight matchings to find an assignment of tasks to processors which minimizes the total interprocessor communication cost while meeting a constraint on the number of tasks assigned to each processor

Distributed Shared Memory: A Survey of Issues and Algorithms

26 pagesA distributed shared memory (DSM) is an implementation of the shared memory abstraction on a multicomputer architecture which has no physically shared memory. Shared memory is important (as a programming model) not only because of the vast number of existing applications which use it, but also because it is a more appropriate paradigm for certain algorithms. The DSM concept was demonstrated to be viable by Li, in IVY. Recently, there has been a surge of new projects which implement DSM in a variety of software and hardware environments. This paper gives an integrated overview of distributed shared memory. We discuss theoretical lower bounds on the performance of DSM systems, design choices such as structure and granularity, access, coherence semantics, scalability, and heterogeneity, and open problems in DSM. In addition, we describe algorithms used to implement and improve efficiency: reducing thrashing, eliminating false sharing, matching the coherence protocol to the type of sharing, and relaxing the semantics of the memory coherence provided. A spectrum of current DSM systems are used as illustrative examples

RAGA: Musical Gantt Charts for Scheduling in Distributed Real Time Systems

22 pagesWe propose a simple extension to Gantt charts, called RAGA scores, for use in distributed real time scheduling. RAGA scores use a small set of symbols borrowed from musical notation to enrich the expressive power of the Gantt chart. These symbols enable the timing constraints of real time tasks to be displayed along with the schedule itself. Because of the criticality of timing constraints in real time systems , it is important to be able to visualize these constraints and the schedule simultaneously. The RAGA score is encapsulated as an abstract data type (ADT) that can be used as a tool in the design and visualization of static and dynamic scheduling algorithms, in the display of real time schedules for performance evaluation through simulation, and for historical records of actual schedules for performance evaluation through 'execution traces.

OREGAMI: Software Tools for Mapping Parallel Computations to Parallel Architectures

22 pagesThe mapping problem in message-passing parallel processors involves the assignment of tasks in a parallel computation to processors and the routing of inter-task messages along the links of the interconnection network. We have developed a unified set of software tools called OREGAMI for automatic and guided mapping of parallel computations to parallel architectures in order to achieve portability and maximal performance from parallel systems. Our tools include a description language which enables the programmer of parallel algorithms to specify information about the static and dynamic communication behavior of the computation to be mapped. This information is used by the mapping algorithms to assign tasks to processors and to route communication in the network topology. Two key features of our system are (a) the ability to take advantage of the regularity present in both the computation structure and the interconnection network and (b) the desire to balance the user's knowledge and intuition with the computational power of efficient combinatorial algorithms

Medicine in context : ten years' experience in diversity education for medical students in Greater Western Sydney, Australia

Objective: This paper describes the Western Sydney University School of Medicine (WSUSoM) diversity education program, Medicine in Context (MiC). MiC implements community-engaged learning and partnership pedagogy in teaching diverse social determinants of health to first clinical year medical students. Central to MiC content and delivery methods is the local region’s diversity which is also reflected in the student population and MiC staff. Methodology: This is a descriptive report about how the WSUSoM staff with community and General Practice (GP) partners have co-designed, co-delivered, co-assessed and co-evaluated the MiC program in 2009-2018. In keeping with the community-engaged learning and partnership pedagogy, the report is co-authored by a cross section of MiC stakeholders: the WSUSoM staff members, community partners and an alumna. Results: Ten weeks' immersion in community-based services, with debriefing and scaffolding in tutorials and workshops, exposes students to the complex interplay between social determinants of health and clinical practice. Sharing of experiences, insights and reflections in safe environments enables students to overcome the uneasiness of diversity education. Quality assurance reviews identified positive trends in students’ quality of learning and satisfaction in the program following evidence-based continuous improvements of the program design and delivery. Conclusion: Implementation of community-engaged learning and partnership pedagogy in the MiC program, supported by ongoing commitment from the WSUSoM and its community and GP partners, has been successful in engaging students in diversity education. The synthesis of diversity education and clinical learning throughout the MiC program is an important step toward building competency in patient-centred care

Epithelial to Mesenchymal Transition by TGFβ-1 Induction Increases Stemness Characteristics in Primary Non Small Cell Lung Cancer Cell Line

Cancer Stem Cells (CSCs) hypothesis asserts that only a small subset of cells within a tumour is capable of both tumour initiation and sustainment. The Epithelial-Mesenchymal Transition (EMT) is an embryonic developmental program that is often activated during cancer invasion and metastasis. The aim of this study is to shed light on the relationship between EMT and CSCs by using LC31 lung cancer primary cell line.A549 and LC31 cell lines were treated with 2 ng/ml TGFβ-1 for 30 days, and 80 days, respectively. To evaluate EMT, morphological changes were assessed by light microscopy, immunofluorescence and cytometry for following markers: cytokeratins, e-cadherin, CD326 (epithelial markers) and CD90, and vimentin (mesenchymal markers). Moreover, RT-PCR for Slug, Twist and β-catenin genes were performed. On TGFβ-1 treated and untreated LC31 cell lines, we performed stemness tests such as pneumospheres growth and stem markers expression such as Oct4, Nanog, Sox2, c-kit and CD133. Western Blot for CD133 and tumorigenicity assays using NOD/SCID mice were performed.TGFβ-1 treated LC31 cell line lost its epithelial morphology assuming a fibroblast-like appearance. The same results were obtained for the A549 cell line (as control). Immunofluorescence and cytometry showed up-regulation of vimentin and CD90 and down-regulation of cytocheratin, e-cadherin and CD326 in TGFβ-1 treated LC31 and A549 cell lines. Slug, Twist and β-catenin m-RNA transcripts were up-regulated in TGFβ-1 treated LC31 cell line confirming EMT. This cell line showed also over-expression of Oct4, Nanog, Sox2 and CD133, all genes of stemness. In addition, in TGFβ-1 treated LC31 cell line, an increased pneumosphere-forming capacity and tumours-forming ability in NOD/SCID mice were detectable.The induction of EMT by TGFβ-1 exposure, in primary lung cancer cell line results in the acquisition of mesenchymal profile and in the expression of stem cell markers

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Risk of Recurrent Arterial Ischemic Stroke in Childhood: A Prospective International Study.

Background and purposePublished cohorts of children with arterial ischemic stroke (AIS) in the 1990s to early 2000s reported 5-year cumulative recurrence rates approaching 20%. Since then, utilization of antithrombotic agents for secondary stroke prevention in children has increased. We sought to determine rates and predictors of recurrent stroke in the current era.MethodsThe Vascular Effects of Infection in Pediatric Stroke (VIPS) study enrolled 355 children with AIS at 37 international centers from 2009 to 2014 and followed them prospectively for recurrent stroke. Index and recurrent strokes underwent central review and confirmation, as well as central classification of causes of stroke, including arteriopathies. Other predictors were measured via parental interview or chart review.ResultsOf the 355 children, 354 survived their acute index stroke, and 308 (87%) were treated with an antithrombotic medication. During a median follow-up of 2.0 years (interquartile range, 1.0-3.0), 40 children had a recurrent AIS, and none had a hemorrhagic stroke. The cumulative stroke recurrence rate was 6.8% (95% confidence interval, 4.6%-10%) at 1 month and 12% (8.5%-15%) at 1 year. The sole predictor of recurrence was the presence of an arteriopathy, which increased the risk of recurrence 5-fold when compared with an idiopathic AIS (hazard ratio, 5.0; 95% confidence interval, 1.8-14). The 1-year recurrence rate was 32% (95% confidence interval, 18%-51%) for moyamoya, 25% (12%-48%) for transient cerebral arteriopathy, and 19% (8.5%-40%) for arterial dissection.ConclusionsChildren with AIS, particularly those with arteriopathy, remain at high risk for recurrent AIS despite increased utilization of antithrombotic agents. Therapies directed at the arteriopathies themselves are needed

Menstrual and Reproductive Factors and Risk of Gastric and Colorectal Cancer in Spain

BACKGROUND: Sex hormones play a role in gastric cancer and colorectal cancer etiology, however, epidemiological evidence is inconsistent. This study examines the influence of menstrual and reproductive factors over the risk of both tumors. METHODS: In this case-control study 128 women with gastric cancer and 1293 controls, as well as 562 female and colorectal cancer cases and 1605 controls were recruited in 9 and 11 Spanish provinces, respectively. Population controls were frequency matched to cases by age and province. Demographic and reproductive data were directly surveyed by trained staff. The association with gastric, colon and rectal cancer was assessed using logistic and multinomial mixed regression models. RESULTS: Our results show an inverse association of age at first birth with gastric cancer risk (five-year trend: OR = 0.69; p-value = 0.006). Ever users of hormonal contraception presented a decreased risk of gastric (OR = 0.42; 95%CI = 0.26-0.69), colon (OR = 0.64; 95%CI = 0.48-0.86) and rectal cancer (OR = 0.61; 95%CI = 0.43-0.88). Postmenopausal women who used hormone replacement therapy showed a decreased risk of colon and rectal tumors. A significant interaction of educational level with parity and months of first child lactation was also observed. CONCLUSION: These findings suggest a protective role of exogenous hormones in gastric and colorectal cancer risk. The role of endogenous hormones remains unclear

Increased Expression of Fatty-Acid and Calcium Metabolism Genes in Failing Human Heart

Heart failure (HF) involves alterations in metabolism, but little is known about cardiomyopathy-(CM)-specific or diabetes-independent alterations in gene expression of proteins involved in fatty-acid (FA) uptake and oxidation or in calcium-(Ca(2+))-handling in the human heart.RT-qPCR was used to quantify mRNA expression and immunoblotting to confirm protein expression in left-ventricular myocardium from patients with HF (n = 36) without diabetes mellitus of ischaemic (ICM, n = 16) or dilated (DCM, n = 20) cardiomyopathy aetiology, and non-diseased donors (CTL, n = 6).Significant increases in mRNA of genes regulating FA uptake (CD36) and intracellular transport (Heart-FA-Binding Protein (HFABP)) were observed in HF patients vs CTL. Significance was maintained in DCM and confirmed at protein level, but not in ICM. mRNA was higher in DCM than ICM for peroxisome-proliferator-activated-receptor-alpha (PPARA), PPAR-gamma coactivator-1-alpha (PGC1A) and CD36, and confirmed at the protein level for PPARA and CD36. Transcript and protein expression of Ca(2+)-handling genes (Two-Pore-Channel 1 (TPCN1), Two-Pore-Channel 2 (TPCN2), and Inositol 1,4,5-triphosphate Receptor type-1 (IP3R1)) increased in HF patients relative to CTL. Increases remained significant for TPCN2 in all groups but for TPCN1 only in DCM. There were correlations between FA metabolism and Ca(2+)-handling genes expression. In ICM there were six correlations, all distinct from those found in CTL. In DCM there were also six (all also different from those found in CTL): three were common to and three distinct from ICM.DCM-specific increases were found in expression of several genes that regulate FA metabolism, which might help in the design of aetiology-specific metabolic therapies in HF. Ca(2+)-handling genes TPCN1 and TPCN2 also showed increased expression in HF, while HF- and CM-specific positive correlations were found among several FA and Ca(2+)-handling genes