TWO-ILLUMINANT ESTIMATION AND USER-PREFERRED CORRECTION FOR IMAGE COLOR CONSTANCY

Master'sMASTER OF SCIENC

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

Noise Modelling for Smartphone Cameras

In our everyday life we capture photographs. We create these images by measuring the amount of light, radiated from scenes in our physical world, on camera sensors embedded in our smartphones. Image noise is variation in the measurement of intensities or colours in digital images and it has the undesirable effect of obscuring information in images. Image noise is produced from two main sources: (1) the unavoidable, random nature of light and (2) the imaging sensor and associated circuitry. Unlike professional cameras, smartphone cameras have much smaller imaging sensors which makes them more susceptible to higher and more complex noise. To model, and ultimately remove, image noise, many mathematical models have been proposed. These models either represent synthetic noise or rely on assumptions that makes them unable to model real noise distributions observed from empirical data. One major reason for that is the lack of sufficient real noisy image datasets with ground truth images that can enable the study of real camera noise. The purpose of this dissertation is to provide a study on image noise modelling based on data-driven approaches specific to smartphone cameras. To this end, we first propose a systematic method for estimating ground truth noise-free images from noisy images captured by smartphone cameras. Using the proposed method, we collect a large-scale dataset, termed the Smartphone Image Denoising Dataset (SIDD), of high-quality images that can be used for noise modelling. Next, we utilize the SIDD dataset to devise a generative noise model, termed Noise Flow, that can be used to synthesise realistic noisy images to be utilized in many computer vision tasks. We also use our datatset to provide a benchmark for image denoising algorithms on real noisy images. As part of this benchmarking effort, we have developed an online image denoising challenge with the necessary software tools to facilitate the evaluation of image denoising methods applied to realistic noisy images. We believe the work in this dissertation helps to advance the state of the art in image noise modelling and image denoising

Seroprevalence and associated risk factors for bovine leptospirosis in Egypt

Abstract Leptospirosis is caused by pathogenic bacteria of the genus Leptospira and is one of causative agents of reproductive problems leading to negative economic impact on bovine worldwide. The goal of this study was to investigate the seroprevalence of Leptospira spp. in cattle in some governorates of Egypt's Nile Delta and assess the risk factors for infection. A total of 410 serum samples were collected from cattle and examined using microscopic agglutination test. The overall seroprevalence was 10.2% and the most prevalent serovars were Icterohaemorrhagiae, Pomona and Canicola. In addition, the potential risk factors were associated Leptospira spp. infection were age, herd size, history of abortion, presence of dogs and rodent control. Thus, leptospirosis is common in dairy cattle in the Nile Delta and  the presence of rodents in feed and dog-accessible pastures increases the risk of Leptospira spp. infection among animals

Investigation on Thermally Evaporated Aluminium Contact Layers for Perovskite Solar Cell Applications

Perovskite solar cells (PSCs) have gained wide interest due to their high device efficiency of up to 22.1%. Perovskite solar cells are comprised of five main layers: fluorine-doped tin oxide (FTO) glass, titanium dioxide (TiO2) electron transport layer (ETL), perovskite active layer, Spiro-OMeTAD hole transport layer (HTL), and a metal contact layer. The metal contact layer plays a significant role in collecting and transporting the generated current and hence governs the performance of the device. Aluminium (Al) is more cost-efficient than the commonly used silver (Ag) or gold (Au) contact layers in perovskite solar cells. The aim of this work is to investigate the influence of different thicknesses and surface morphologies on the electrical properties of the Al thin film contact layers for perovskite solar cell applications. The Al contact layers were deposited using a thermal evaporator with varying Al wire source lengths at constant deposition duration and pressure. The deposited films were characterised for thickness, morphology, and electrical properties using a stylus profilometer, an atomic force microscope, and a four-point probe, respectively. Results showed that thicker Al films have larger particle sizes as compared to the thinner films, demonstrating a more continuous film morphology. Resistivity and conductivity show a variance with different film thickness. Based on literature, higher conductivity and larger particle sizes of the metal contact layers can improve charge transportation, which contributes to the performance of the perovskite solar cell

Electrochromic Properties of Sol-Gel Deposited Electrochromic TiO2 Thin Films

Electrochromic (EC) smart windows are a type of glass window that can change from transparent to darker colour shades when a small voltage is applied. Titanium dioxide (TiO2) can be utilised as an EC material for EC smart windows. Although the TiO2 sol-gel spin-coating method is commonly used, the effect of the number of TiO2 layers was not reported. Thus, this paper investigates the effect of the number of TiO2layers. The increasing number of TiO2film layers demonstrated a noticeable increase in the thin films ‘anodic and cathodic diffusion coefficient, particularly with 11 TiO2layers. Additionally, the colouration and bleaching time was revealed to have a low correlation as the number of layers increased. Nonetheless, the lower number of TiO2layers resulted in lower colouring transmittance. Comparatively, the colouration efficiency for all films did not exhibit any significant change. Hence this study on the effect of the TiO2layering technique can open a new pathway in understanding the EC properties of TiO2-based EC devices