Cooperative cache scrubbing

Managing the limited resources of power and memory bandwidth while improving performance on multicore hardware is challeng-ing. In particular, more cores demand more memory bandwidth, and multi-threaded applications increasingly stress memory sys-tems, leading to more energy consumption. However, we demon-strate that not all memory traffic is necessary. For modern Java pro-grams, 10 to 60 % of DRAM writes are useless, because the data on these lines are dead- the program is guaranteed to never read them again. Furthermore, reading memory only to immediately zero ini-tialize it wastes bandwidth. We propose a software/hardware coop-erative solution: the memory manager communicates dead and zero lines with cache scrubbing instructions. We show how scrubbing instructions satisfy MESI cache coherence protocol invariants and demonstrate them in a Java Virtual Machine and multicore simula-tor. Scrubbing reduces average DRAM traffic by 59%, total DRAM energy by 14%, and dynamic DRAM energy by 57 % on a range of configurations. Cooperative software/hardware cache scrubbing reduces memory bandwidth and improves energy efficiency, two critical problems in modern systems

Study protocol: Home-based physical rehabilitation for survivors of a critical illness [ACTRN12605000166673]

INTRODUCTION: Numerous primary studies and several review papers have highlighted delayed physical and psychological recovery for survivors of critical illness, often beyond 6 months after discharge. This randomized controlled trial with blinded assessment aims to test the effects of an 8-week, home-based, individually tailored physical rehabilitation programme on physical and psychological recovery for survivors of a critical illness after discharge from hospital. METHOD: Participants are survivors of a critical illness discharged from nine intensive care units (ICUs) in Australia, who are aged 18 years or older, in an ICU longer than 48 hours, discharged home to self-care or carer (non-institutional care), able to participate in physical rehabilitation, and within the hospitals' local geographical areas for home visits. The study is based in participants' home environments. Blinded assessments at weeks 1, 8 and 26 after hospital discharge examine physical functioning, exercise capacity, health-related quality of life and psychological well being. The intervention is graded, individualized endurance and strength training prescribed by a pulmonary rehabilitation physiotherapist over an 8-week period, with three home visits, five follow-up phone calls, and a printed exercise manual supporting the training. Initial focus is on lower limb exercises and walking, with warm-up stretches, and progresses to the addition of core stabilization and upper limb exercises. RESULTS: The burden of a critical illness is well documented. This novel study will determine whether a home-based physical rehabilitation programme improves the recovery trajectory for survivors of critical illness. The projected sample size of 200 patients aims to detect a clinically important 10% improvement in physical functioning. The study will also examine whether other important physical and psychological measures are improved. CONCLUSION: This multicentre, randomized controlled trial will examine outcomes that are meaningful to patients, their family and society, namely functional ability and well being. The study will also target a health problem that is likely to increase as the population ages. If the programme is effective, it will provide a model that can be easily adapted and adopted by existing primary care or community services to improve the recovery of individuals following critical illness

Surficial and deep earth material prediction from geochemical compositions

Prediction of true classes of surficial and deep earth materials using multivariate spatial data is a common challenge for geoscience modelers. Most geological processes leave a footprint that can be explored by geochemical data analysis. These footprints are normally complex statistical and spatial patterns buried deep in the high-dimensional compositional space. This paper proposes a spatial predictive model for classification of surficial and deep earth materials derived from the geochemical composition of surface regolith. The model is based on a combination of geostatistical simulation and machine learning approaches. A random forest predictive model is trained, and features are ranked based on their contribution to the predictive model. To generate potential and uncertainty maps, compositional data are simulated at unsampled locations via a chain of transformations (isometric log-ratio transformation followed by the flow anamorphosis) and geostatistical simulation. The simulated results are subsequently back-transformed to the original compositional space. The trained predictive model is used to estimate the probability of classes for simulated compositions. The proposed approach is illustrated through two case studies. In the first case study, the major crustal blocks of the Australian continent are predicted from the surface regolith geochemistry of the National Geochemical Survey of Australia project. The aim of the second case study is to discover the superficial deposits (peat) from the regional-scale soil geochemical data of the Tellus Project. The accuracy of the results in these two case studies confirms the usefulness of the proposed method for geological class prediction and geological process discovery

The effects of lead sources on oral bioaccessibility in soil and implications for contaminated land risk management

Lead (Pb) is a non-threshold toxin capable of inducing toxic effects at any blood level but availability of soil screening criteria for assessing potential health risks is limited. The oral bioaccessibility of Pb in 163 soil samples was attributed to sources through solubility estimation and domain identification. Samples were extracted following the Unified BARGE Method. Urban, mineralisation, peat and granite domains accounted for elevated Pb concentrations compared to rural samples. High Pb solubility explained moderate-high gastric (G) bioaccessible fractions throughout the study area. Higher maximum G concentrations were measured in urban (97.6 mg kg−1) and mineralisation (199.8 mg kg−1) domains. Higher average G concentrations occurred in mineralisation (36.4 mg kg−1) and granite (36.0 mg kg−1) domains. Findings suggest diffuse anthropogenic and widespread geogenic contamination could be capable of presenting health risks, having implications for land management decisions in jurisdictions where guidance advises these forms of pollution should not be regarded as contaminated land

In Solidarity

This edition of Next Page is a departure from our usual question and answer format with a featured campus reader. Instead, we asked speakers who participated in the College’s recent Student Solidarity Rally (March 1, 2017) to recommend readings that might further our understanding of the topics on which they spoke

Association between community-based self-reported COVID-19 symptoms and social deprivation explored using symptom tracker apps: A repeated cross-sectional study in Northern Ireland

Objectives: The aim of the study was to investigate the spatial and temporal relationships between the prevalence of COVID-19 symptoms in the community-level and area-level social deprivation. Design: Spatial mapping, generalised linear models, using time as a factor and spatial-lag models were used to explore the relationship between self-reported COVID-19 symptom prevalence as recorded through two smartphone symptom tracker apps and a range of socioeconomic factors using a repeated cross-sectional study design. Setting: In the community in Northern Ireland, UK. The analysis period included the earliest stages of non-pharmaceutical interventions and societal restrictions or \u27lockdown\u27 in 2020. Participants: Users of two smartphone symptom tracker apps recording self-reported health information who recorded their location as Northern Ireland, UK. Primary outcome measures: Population standardised self-reported COVID-19 symptoms and correlation between population standardised self-reported COVID-19 symptoms and area-level characteristics from measures of multiple deprivation including employment levels and population housing density, derived as the mean number of residents per household for each census super output area. Results: Higher self-reported prevalence of COVID-19 symptoms was associated with the most deprived areas (p \u3c 0.001) and with those areas with the lowest employment levels (p \u3c 0.001). Higher rates of self-reported COVID-19 symptoms within the age groups, 18-24 and 25-34 years were found within the most deprived areas during the earliest stages of non-pharmaceutical interventions and societal restrictions (\u27lockdown\u27). Conclusions: Through spatial regression of self-reporting COVID-19 smartphone data in the community, this research shows how a lens of social deprivation can deepen our understanding of COVID-19 transmission and prevention. Our findings indicate that social inequality, as measured by area-level deprivation, is associated with disparities in potential COVID-19 infection, with higher prevalence of self-reported COVID-19 symptoms in urban areas associated with area-level social deprivation, housing density and age

Health-related quality of life and physical recovery after a critical illness: a multi-centre randomised controlled trial of a home-based physical rehabilitation program

Introduction: Significant physical sequelae exist for some survivors of a critical illness. There are, however, few studies that have examined specific interventions to improve their recovery, and none have tested a home-based physical rehabilitation program incorporating trainer visits to participants' homes. This study was designed to test the effect of an individualised eight-week home-based physical rehabilitation program on recovery. Methods: A multi-centre randomised controlled trial design was used. Adult intensive care patients (length of stay of at least 48 hours and mechanically ventilated for 24 hours or more) were recruited from 12 Australian hospitals between 2005 and 2008. Graded, individualised endurance and strength training intervention was prescribed over eight weeks, with three physical trainer home visits, four follow-up phone calls, and supported by a printed exercise manual. The main outcome measures were blinded assessments of physical function; SF-36 physical function (PF) scale and six-minute walk test (6MWT), and health-related quality of life (SF-36) conducted at 1, 8 and 26 weeks after hospital discharge. Results: Of the 195 participants randomised, 183, 173 and 161 completed the 1, 8 and 26 weeks assessments, respectively. Study groups were similar at Week 1 post-hospital; for the intervention and control groups respectively, mean norm-based PF scores were 27 and 29 and the 6MWT distance was 291 and 324 metres. Both groups experienced significant and clinically important improvements in PF scores and 6MWT distance at 8 weeks, which persisted at 26 weeks. Mixed model analysis showed no significant group effects (P = 0.84) or group by time interactions (P = 0.68) for PF. Similar results were found for 6MWT and the SF-36 summary scores. Conclusions: This individualised eight-week home-based physical rehabilitation program did not increase the underlying rate of recovery in this sample, with both groups of critically ill survivors improving their physical function over the 26 weeks of follow-up. Further research should explore improving effectiveness of the intervention by increasing exercise intensity and frequency, and identifying individuals who would benefit most from this intervention. Trial registration: Australia and New Zealand Clinical Trials Register ACTRN1260500016667

Investigating relations between environmental toxins in Northern Irish soils and streams and Chronic Kidney Disease prevalence

The unknown aetiology of Chronic Kidney Disease (CKD) has attracted recent attention as a result of the increasing global prevalence and recent reviews of occupational and environmental exposure to nephrotoxins. The main focus of this research is to examine the potential relationship between environmental exposure to known nephrotoxins including arsenic, cadmium and lead and the potential health risk associated with the progressive dysfunction of the kidneys in renal impaired patients with CKD across Northern Ireland. In addition to these known nephrotoxins, co-abundance with several essential elements has been found to play a role as protecting mechanisms while others increase the uptake of nephrotoxic elements as a result of similar absorption mechanisms within the body. Key elements protecting the body from toxicity include selenium and zinc, whereas those which have been attributed to enhance the uptake of arsenic, cadmium and lead include iron and calcium. The compositional nature of the soil and stream geochemical data is explored to aid in the analysis of interactions between elements. Two approaches, one data-driven and the other knowledge-driven, are explored to investigate the associations between co-abundant elements. The bioaccessibility of these elements, which is the portion of the relevant toxin absorbed within the body, is also investigated to identify areas across Northern Ireland with an increased environmental hazard and potential health risk. The study uses a combination of datasets from the United Kingdom Renal Registry (UKRR) unknown aetiology subset, the soil and stream geochemical dataset from the Tellus Survey (GSNI) with the addition of a bioaccessibility subset. Findings suggest a relationship between the presence of elevated arsenic in stream waters and impaired renal function of the kidneys. Interactions between essential elements and potentially toxic elements could explain the regional variation of CKD of uncertain aetiology across Northern Ireland