Overload Protection for CORBA Systems with Time Constraints

Scalable and reliable distributed object-oriented computing (DOC) middleware systems is an important technology in, for example, telecommunications service logic and distributed web servers. The Common Object Request Broker Architecture (CORBA), developed by the Object Management Group (OMG) is a speci cation of a common platform for DOC systems. CORBA acts as middleware, by inserting itself between the Operating System (OS) layer and the Application layer on a host. CORBA provides support for transparent interaction of objects situated on different nodes. The original CORBA specications had no support for timing constraints in applications and very little support in the terms of performance optimizations. Present extension to CORBA include support for real-time applications and a number of performance enhancements such as load balancing. However, no work so far address the issue of overload in a CORBA system. This paper presents a discussion of overload issues in distributed CORBA systems with time-constrained tasks. First a performance model of a CORBA system is introduced. Second, overload in distributed CORBA systems is discussed. Third, a number of classic overload protection mechanisms are applied to the performance model and investigated using simulation. The simulations show that even by using very simple protection mechanism, a good throughput can be achieved

Load Reduction for Timely Applications in the Cloud

In many IoT applications, sensor data is sent remotely to be processed, but only the freshest result is of interest. In this paper we investigate a feedback mechanism that aborts the processing of stale data at the remote end to reduce the load and save costs. The process is approximated by an M/M/∞ queueing system with a feedback loop. We find the exact expression of the average computational time saved and show that with the feedback loop in place the computation time per CPU can be cut up to 25%, making the technique very promising

Design and evaluation of an overload control system for crisis-related Web server systems

During recent years we have seen several large-scale crises. The 9/11 terror attacks, tsunamis, storms, floods and bombings have all caused a great deal of damage. A common factor in these crises has been the need for information and one important source of information is usually Web sites. In this work we investigate and design an overload control system for Web sites that are vital in crises. The overload control system uses content adaption to dynamically control Web site performanc

Simulation of a distributed CORBA-based SCP

This paper examines load balancing issues relating to a distributed CORBA-based Service Control Point. Two types of load balancing strategies are explored through simulation studies: (i) a novel ant-based load balancing algorithm, which has been devised specically for this type of system. This algorithm is compared to more traditional algorithms, (ii) a method for optimal distribution of the computational objects composing the service programs. This is based on mathematically minimising the expected communication ows between network nodes and message-level processing costs. The simulation model has been based on the recently adopted OMG IN/CORBA Interworking specication and the TINA Service Session computational object model

Manual authentication for wireless devices

Manual authentication techniques have been designed to enable wireless devices to authenticate one another via an insecure wireless channel with the aid of a manual transfer of data between the devices. Manual transfer refers to the human operator of the devices performing one of the following procedures; copying data output from one device into the other device, comparing the output of the two devices, or entering the same data into both devices. Techniques currently being standardised are described which achieve this, and which require only small amounts of data to be transferred between the two devices. This makes the mechanisms particularly attractive for non-expert use, as required for ubiquitous mobile wireless devices

Hospital-treated infectious diseases and the risk of dementia : a large, multicohort, observational study with a replication cohort

Background Infections have been hypothesised to increase the risk of dementia. Existing studies have included a narrow range of infectious diseases, relied on short follow-up periods, and provided little evidence for whether the increased risk is limited to specific dementia subtypes or attributable to specific microbes rather than infection burden. We aimed to compare the risk of Alzheimer's disease and other dementias across a wide range of hospital-treated bacterial and viral infections in two large cohorts with long follow-up periods. Methods In this large, multicohort, observational study, the analysis was based on a primary cohort consisting of pooled individual-level data from three prospective cohort studies in Finland (the Finnish Public Sector study, the Health and Social Support study, and the Still Working study) and an independent replication cohort from the UK Biobank. Community-dwelling adults (>= 18 years) with no dementia at study entry were included. Follow-up was until Dec 31, 2012, in the Health and Social Support study, Dec 31, 2016, in the public sector study and the Still Working study, and Feb 7, 2018, in the replication cohort. Through record linkage to national hospital inpatient registers, we ascertained exposure to 925 infectious diseases (using the International Classification of Diseases 10th Revision codes) before dementia onset, and identified incident dementia from hospital records, medication reimbursement entitlements, and death certificates. Hazard ratios (HRs) for the associations of each infectious disease or disease group (index infection) with incident dementia were assessed by use of Cox proportional hazards models. We then repeated the analysis after excluding incident dementia cases that occurred during the first 10 years after initial hospitalisation due to the index infection. Findings From March 1, 1986, to an 1, 2005, 260 490 people were included in the primary cohort, and from Dec 19, 2006, to Oct 1, 2010, 485 708 people were included in the replication cohort. In the primary cohort analysis based on 3 947 046 person-years at risk (median follow-up 15.4 years [IQR 9- 8-21- 0]), 77108 participants had at least one hospital-treated infection before dementia onset and 2768 developed dementia. Hospitalisation for any infectious disease was associated with increased dementia risk in the primary cohort (adjusted HR laHRI 1.48 [95% CI 1. 37-1- 60]) and replication cohort (2.60 [2. 38-2- 83]). The association remained when analyses were restricted to new dementia cases that occurred more than 10 years after infection (aHR 1.22 [95% CI 1.09-1.36] in the primary cohort, the replication cohort had insufficient follow-up data for this analysis), and when comorbidities and other dementia risk factors were considered. There was evidence of a dose-response association between the number of episodes of hospital-treated infections and dementia risk in both cohorts (p(trend) =0- 0007). Although the greatest dementia risk was seen for central nervous system (CNS) infections versus no infection (aHR 3.01 [95% CI 2- 07-4 center dot 37]), excess risk was also evident for extra-CNS infections (1.47 [1.36-1.59]). Although we found little difference in the infection-dementia association by type of infection, associations were stronger for vascular dementia than for Alzheimer's disease (aHR 2.09 [95% CI 1- 59-2- 75] versus aHR 1.20 [1.08-1.33] in the primary cohort and aHR 3.28 [2- 65-4 center dot 04] versus aHR 1.80 [1.53-2-13] in the replication cohort). Interpretation Severe infections requiring hospital treatment are associated with long-term increased risk of dementia, including vascular dementia and Alzheimer's disease. This association is not limited to CNS infections, suggesting that systemic effects are sufficient to affect the brain. The absence of infection specificity combined with evidence of dose-response relationships between infectious disease burden and dementia risk support the hypothesis that increased dementia risk is driven by general inflammation rather than specific microbes. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd.Peer reviewe

PL - 026 Mismatch between skeletal muscle glucose delivery, interstitial concentration and membrane permeability may limit insulin sensitivity after exercise

Objective The relationship between skeletal muscle perfusion, interstitial glucose concentration and sarcolemmal permeability to glucose in exercise-induced increases in muscle insulin sensitivity is not well established. A single bout of exercise increases skeletal muscle insulin sensitivity through coordinated increases in insulin-stimulated microvascular perfusion and insulin signalling  Reducing leg and muscle microvascular blood flow with local nitric oxide synthase (NOS) inhibition during a hyperinsulinaemic euglycaemic clamp reduces leg glucose uptake in a previously exercised, but not in a contralateral non-exercised leg, without affecting insulin signalling in either leg  (Sjoberg et al. 2017). Therefore, it is possible that the reduction in muscle perfusion decreases muscle interstitial glucose concentration to a point that limits skeletal muscle insulin-stimulated glucose uptake following exercise. We examined this using microdialysis of vastus lateralis muscle. Methods Ten healthy males (Age: 27±1 yr., Weight: 77.7±2.3 kg, BMI 23.9±0.5, VO2 peak: 50.7±1.5 ml·kg-1·min-1) performed 60 min of 1-legged knee extensor exercise at 80% of 1-legged peak work load with three 5 min intervals at 100% 1-legged peak work load. Participants then rested for 4 hours and catheters were inserted into the femoral artery and vein of both legs for subsequent measurement of leg glucose uptake and for femoral artery infusion of the NOS inhibitor NG-monomethyl L-arginine acetate (L-NMMA) and the vasodilator ATP. Catheters were also placed in antecubital veins for infusion of insulin and glucose. Three microdialysis catheters, with a semi-permeable membrane the length of 30 mm and a molecular cut-off at 20,000 dalton, were inserted into the vastus lateral muscle of both legs. Glucose and D-[6-3H(N)]glucose were added to the perfusate. Four hours after discontinuing the exercise a 225 minute euglycaemic hyperinsulinaemic clamp was initiated (insulin infusion 1.4 mU-1kg-1min). Ninety min into the clamp L-NMMA was infused at a constant rate (0.4 mg·kg-1 leg mass·min-1) into both femoral arteries for 45 min. The insulin infusion was maintained for another 90 min and during the last 45 min ATP (0.3 μmol∙ml-1) was infused locally into both femoral arteries at a rate of 200-350 μl∙min-1 to obtain a leg blood flow that was double the blood flow during insulin only infusion. A second control protocol was undertaken that was identical in regards to exercise and recovery but no insulin, L-NMMA or ATP was infused. Results During the clamp leg glucose uptake and leg blood flow were higher (P<0.05) in the previously exercised than the control leg whereas the interstitial glucose concentration decreased to lower (P<0.05) values in the exercised (~3.1mM) than the control (~4.8mM) leg. Estimated sarcolemmal glucose permeability was twice as high (P<0.05) in the exercised compared with the rested leg. The NOS inhibitor L-NMMA decreased LBF in both legs and interstitial glucose concentration dropped to ~2.3 mM in the exercised but only to ~3.7 mM in non-exercised muscle. This abrogated the augmented effect of insulin on LGU in the exercised leg while apparent sarcolemmal permeability to glucose remained unchanged with L-NMMA in both legs. Doubling leg blood flow by local infusion of ATP increased leg glucose uptake in both legs without any major change in interstitial glucose concentration or sarcolemmal permeability to glucose. Conclusions These findings suggest that during flow restriction due to L-NMMA, the interstitial glucose concentration becomes limiting for leg glucose uptake in exercised but not in non-exercised muscle. Therefore, the vasodilatory effect of insulin is an important component of the increased insulin sensitivity to stimulate glucose uptake following exercise by limiting the drop in the interstitial glucose concentration that occurs due to the increased sarcolemmal permeability to glucose. Reference Sjoberg, K. A., C. Frosig, R. Kjobsted, L. Sylow, M. Kleinert, A. C. Betik, C. S. Shaw, B. Kiens, J. F. P. Wojtaszewski, S. Rattigan, E. A. Richter, and G. K. McConell. Exercise Increases Human Skeletal Muscle Insulin Sensitivity via Coordinated Increases in Microvascular Perfusion and Molecular Signaling.  Diabetes  66: 1501-10, 2017

Healthy minds 0-100 years: Optimising the use of European brain imaging cohorts ("Lifebrain").

The main objective of "Lifebrain" is to identify the determinants of brain, cognitive and mental (BCM) health at different stages of life. By integrating, harmonising and enriching major European neuroimaging studies across the life span, we will merge fine-grained BCM health measures of more than 5000 individuals. Longitudinal brain imaging, genetic and health data are available for a major part, as well as cognitive and mental health measures for the broader cohorts, exceeding 27,000 examinations in total. By linking these data to other databases and biobanks, including birth registries, national and regional archives, and by enriching them with a new online data collection and novel measures, we will address the risk factors and protective factors of BCM health. We will identify pathways through which risk and protective factors work and their moderators. Exploiting existing European infrastructures and initiatives, we hope to make major conceptual, methodological and analytical contributions towards large integrative cohorts and their efficient exploitation. We will thus provide novel information on BCM health maintenance, as well as the onset and course of BCM disorders. This will lay a foundation for earlier diagnosis of brain disorders, aberrant development and decline of BCM health, and translate into future preventive and therapeutic strategies. Aiming to improve clinical practice and public health we will work with stakeholders and health authorities, and thus provide the evidence base for prevention and intervention.This research is funded by the EU Horizon 2020 Grant: ‘Healthy minds 0–100 years: Optimising the use of European brain imaging cohorts (“Lifebrain”)’. Grant agreement number: 732592. Call: Societal challenges: Health, demographic change and well-bein

Educational attainment does not influence brain aging.

Education has been related to various advantageous lifetime outcomes. Here, using longitudinal structural MRI data (4,422 observations), we tested the influential hypothesis that higher education translates into slower rates of brain aging. Cross-sectionally, education was modestly associated with regional cortical volume. However, despite marked mean atrophy in the cortex and hippocampus, education did not influence rates of change. The results were replicated across two independent samples. Our findings challenge the view that higher education slows brain aging

Preconceptional Folate Supplementation and the Risk of Spontaneous Preterm Birth: A Cohort Study

In an analysis of a cohort of pregnant women, Radek Bukowski and colleagues describe an association between taking folic acid supplements and a reduction in the risk of preterm birth