Peer-to-peer update dissemination in browser-based networked virtual environments.

PhD ThesisNetworked Virtual Environments (NVEs) have always imposed strict requirements on architectures for update dissemination (UD). Clients must maintain views that are as synchronous and consistent as possible in order to achieve a level of user experience that is tolerable for the user. In recent times, the web browser has become a viable platform on which to deploy these NVEs. Doing so adds another layer of challenges however. There is a distinct need for systems that adapt to these constraints and exploit the characteristics of this new context to achieve reliably high consistency between users for a range of use cases. A promising approach is to carry forward the rich body of past research in peer-to-peer (P2P) networks and apply this to the problem of UD in NVEs under the constraints of a web browser. Making NVEs scalable through P2P networks is not a new concept, however previous work has always been either too specific to a certain kind of NVE, or made performance trade-offs that especially cannot work in a browser context. Furthermore, in previous work on P2P NVEs, UD has always taken the backseat compared to object management and distributed neighbour selection. The evaluation of these UD systems have as a result been one-dimensional and overly simplifying. In this work, we begin by surveying past UD solutions and evaluation methodologies. We then capture NVE, browser, and network constraints, aided by the analysis of a rich dataset of NVE network traces that we have collected, and draw out key observations and challenges to develop the requirements for a feasible UD system. From there, we illustrate the design and implementation of our P2P UD system for NVEs in great detail, augmenting our system with novel architectural insights from the Software-Defined Networking (SDN) space. Finally, we evaluate our system under a range of workloads, test environments, and performance metrics to demonstrate that we have overcome these challenges, as well as compare our method to other existing methods, which we have also implemented and tested. We hope that our contributions in research and resources (such as our taxonomies, NVE analysis, UD system, browser library, workload datasets, and a benchmarking framework) bring more structure as well as research and development opportunities to a relatively niche sub-field

Optimizing Parabolic Through Collectors for Solar Stills: A 2D CFD Parametric Analysis

The thermal efficiency of parabolic trough collectors (PTCs) is influenced by various parameters, including length, diameter, and mass flow rate. This study employs 2D steady-state Computational Fluid Dynamics (CFD) simulations to investigate heat transfer within PTCs and enhance their performance. Exploring diverse PTC designs, involving variations in length (L = 0.5 to 3 m) and diameter (D = 10 to 60 mm), sourced from existing research to optimize desalination system applications. The investigation covers both laminar and turbulent regimes with fully developed flows, examining the effects of Reynolds number and mass flow rate. The results highlight that collector diameter has the most pronounced impact on thermal efficiency, followed by mass flow rate, while the effect of length can be neglected in comparison. A 50% diameter increase leads to over a 60% rise in efficiency for both laminar and turbulent cases, whereas a 60% decrease in mass flow rate corresponds to a 50% enhancement and a 60% improvement in efficiency for both regimes. These findings suggest that an optimal PTC design should prioritize a smaller diameter and lower mass flow rate, with length being of secondary importance and application-specific considerations also playing a pivotal role

Building accountability into the Internet of Things: the IoT Databox model

This paper outlines the IoT Databox model as a means of making the Internet of Things (IoT) accountable to individuals. Accountability is a key to building consumer trust and is mandated by the European Union’s General Data Protection Regulation (GDPR). We focus here on the ‘external’ data subject accountability requirement specified by GDPR and how meeting this requirement turns on surfacing the invisible actions and interactions of connected devices and the social arrangements in which they are embedded. The IoT Databox model is proposed as an in principle means of enabling accountability and providing individuals with the mechanisms needed to build trust into the IoT

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

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Management of a massive choledochal cyst in a 12 year-old girl: Which imaging modalities should be performed preoperatively?

A previously well 12 year-old girl presented to the emergency department with a three-day history of fatigue, pruritus, and epigastric discomfort. Abdominal ultrasound revealed a cystic mass in the right upper quadrant measuring 17.0 × 13.2 × 11.7 cm. Magnetic resonance imaging (MRI) confirmed the diagnosis of a choledochal cyst and hepatobiliary iminodiacetic acid (HIDA) scintigraphy demonstrated a communication between the cyst and biliary tree. Percutaneous cholangiography was also performed but did not provide additional diagnostic information. The patient was brought to the operating room a few days later for open resection of the choledochal cyst, cholecystectomy, and Roux-en-Y hepaticojejunostomy. Frozen sections were obtained to ensure complete excision of cyst mucosa. The patient continues to do well more than 18 months post-operatively with no signs of recurrent inflammation or malignancy. Multiple imaging modalities may be used preoperatively to assess the anatomy and subtype of choledochal cysts. The role of invasive options, such as percutaneous cholangiography or endoscopic retrograde cholangiopancreatograpy (ERCP), remains limited and unclear. Here, we present a potential imaging algorithm to assist with preoperative workup and avoid invasive diagnostic procedures whenever possible

Wheat Straw Burial Enhances the Root Physiology, Productivity, and Water Utilization Efficiency of Rice under Alternative Wetting and Drying Irrigation

This study evaluated whether the straw burial and alternative wetting and drying (AWD) irrigation could improve the root activity, yield, and water utilization efficiency (WUE) of rice. Accordingly, we conducted a field experiment with three straw burial levels, i.e., with no straw burial (NSB), low straw burial 300 kg.ha−1 (LSB), and dense straw burial 800 kg.ha−1 (DSB), and three irrigation regimes, i.e., alternate wetting/moderate drying (AWMD), alternate wetting/severe drying (AWSD), and alternate wetting/critical drying (AWCD). Results showed that straw burial improved the root activity, rice yield, and WUE under AWD regimes. The combination AWMD×DSB resulted in the greatest values of total dry mass (1764.7 g/m2) and water use (853.1 mm). Conversely, the treatment AWCD × NSB led to the lowest values of total biomass (583.3 g/m2) and water use (321.8 mm). Root dry weight density (1.11 g cm−3) and root active absorption area (31.6 m2 plant−1) were higher in the treatment AWMD × DSB than root dry weight density (0.41 g cm−3) and root active absorption area (21.2 m2 plant−1) were in the treatment AWCD×NSB. The former combined treatment increased root oxidation ability (55.5 mg g−1 FWh−1), the root surface phosphatase activity (1.67 mg g−1 FWh−1) and nitrate reductase activity of root (14.4 μg g−1 h−1) while the latter considerably reduced the values of root oxidation ability (21.4 mg g−1 FWh−1), the root surface phosphatase activity (0.87 mg g−1 FWh−1) and nitrate reductase activity of root (5.8 μg g−1 h−1). The following conclusions can be drawn with regard to water use and biomass yield. (i) The reduction in water consumption was greater than the reduction in yield in the case of AWSD. (ii) The decline in water consumption was less than the decline in biomass yield in the case of AWCD. (iii) The increase in in water consumption was greater than the increase in biomass yield in the case of AWMD. Therefore, the indicators of WUE were recorded in the following order: AWSD > AWMD > AWCD. This study recommends AWD irrigation to improve the root growth traits that contribute to the greater biomass yield of rice. It also suggests that farmers should implement AWD irrigation after leaving wheat straw residues in the field, and followed by deep tillage, to mitigate the negative effect of drought stress caused by AWD irrigation, preserving plant growth without large biomass losses, and thus, addressing the constrains of straw residues and sustaining rice production under limited freshwater resources