An efficient RANSAC hypothesis evaluation using sufficient statistics for RGB-D pose estimation

Achieving autonomous flight in GPS-denied environments begins with pose estimation in three-dimensional space, and this is much more challenging in an MAV in a swarm robotic system due to limited computational resources. In vision-based pose estimation, outlier detection is the most time-consuming step. This usually involves a RANSAC procedure using the reprojection-error method for hypothesis evaluation. Realignment-based hypothesis evaluation method is observed to be more accurate, but the considerably slower speed makes it unsuitable for robots with limited resources. We use sufficient statistics of least-squares minimisation to speed up this process. The additive nature of these sufficient statistics makes it possible to compute pose estimates in each evaluation by reusing previously computed statistics. Thus estimates need not be calculated from scratch each time. The proposed method is tested on standard RANSAC, Preemptive RANSAC and R-RANSAC using benchmark datasets. The results show that the use of sufficient statistics speeds up the outlier detection process with realignment hypothesis evaluation for all RANSAC variants, achieving an execution speed of up to 6.72 times

An efficient pose estimation for limited-resourced MAVs using sufficient statistics

Abstract — We present a computationally efficient RGB-D based pose estimation solution for less computationally re-sourced MAVs, which are ideally suited as members in a swarm. Our approach applies the sufficient statistics derived for a least-squares problem to our problem context. RANSAC-based outlier detection in aligning corresponding feature points is a time consuming operation in visual pose estimation. The additive nature of the used sufficient statistics significantly reduces the computation time of the RANSAC procedure since the pose estimation in each test loop can be computed by reusing previously computed sufficient statistics. This eliminates the need for recomputing estimates from scratch each time. A simpler hypotheses testing method gave similar performance in terms of speed but less accurate than our proposed method. We further increase the efficiency by reducing the problem size to four dimensions using attitude data from an Attitude and Heading Reference System (AHRS). Using a real-world dataset, we show that our algorithm saves up to 94 % of computation time for the RANSAC-based procedure in pose estimation while improving the accuracy

Arrangements for Setting Drinking Water Standards

This study forms part of a continuing program of research benchmarking the performance of economic infrastructure industries. Earlier studies have focused on information about outcomes, such as prices and productivity. This study of the water sector, however, compares regulatory processes for the development and enforcement of quality standards, in Australia and overseas, against accepted best practice principles.drinking water - water quality - international benchmarking - water cycle - public health - standards

Scholarly Communication Librarianship and Open Knowledge

The intersection of scholarly communication librarianship and open education offers a unique opportunity to expand knowledge of scholarly communication topics in both education and practice. Open resources can address the gap in teaching timely and critical scholarly communication topics—copyright in teaching and research environments, academic publishing, emerging modes of scholarship, impact measurement—while increasing access to resources and equitable participation in education and scholarly communication. Scholarly Communication Librarianship and Open Knowledge is an open textbook and practitioner’s guide that collects theory, practice, and case studies from nearly 80 experts in scholarly communication and open education. Divided into three parts: *What is Scholarly Communication? *Scholarly Communication and Open Culture *Voices from the Field: Perspectives, Intersections, and Case Studies The book delves into the economic, social, policy, and legal aspects of scholarly communication as well as open access, open data, open education, and open science and infrastructure. Practitioners provide insight into the relationship between university presses and academic libraries, defining collection development as operational scholarly communication, and promotion and tenure and the challenge for open access. Scholarly Communication Librarianship and Open Knowledge is a thorough guide meant to increase instruction on scholarly communication and open education issues and practices so library workers can continue to meet the changing needs of students and faculty. It is also a political statement about the future to which we aspire and a challenge to the industrial, commercial, capitalistic tendencies encroaching on higher education. Students, readers, educators, and adaptors of this resource can find and embrace these themes throughout the text and embody them in their work

Hepatitis B and C in Malawi: Epidemiology, Disease Burden and Opportunities for a Public Health Treatment Programme

Abstract In sub-Saharan Africa, hepatitis B virus (HBV) infection is the principal cause of liver cirrhosis and hepatocellular carcinoma (HCC). Mortality from cirrhosis and HCC is projected to rise beyond 2030 unless adult HBV treatment programmes are implemented. Infant HBV vaccination was introduced across sub-Saharan Africa between 1994-2014, and in Malawi in 2002 where it is given at 6, 10 and 14 weeks of life. Hepatitis C virus (HCV) is an important contributor to liver disease globally, with an estimated population prevalence of 1% in sub-Saharan Africa. In Southern Africa there is a paucity of HCV prevalence data, with no previous random probability-sampling community studies. A hospital-based study of cirrhosis and HCC in a tertiary hospital, and seroprevalence studies in an urban township, were conducted in Blantyre, Malawi, to determine HBV and HCV prevalence and HBV vaccine impact. Of 97,386 censused individuals, single stage non-replacement age-stratified probability sampling was used to select 6,073 individuals who were tested for hepatitis B surface antigen (HBsAg) in a community serosurvey. HBsAg-positive individuals aged ≥16 were recruited to assess treatment eligibility. Among individuals aged ≥16 in the serosurvey, 1661 (51%) were randomly selected for HCV antigen/antibody (Ag/Ab) testing with confirmatory HCV RNA PCR. Prevalence estimates were standardised to census age and sex distribution using post-stratification proportional fitting. In the hospital study, the population attributable fraction (PAF) of HBV to cirrhosis and HCC was 23.1% (95% CI 15.7- 29.8) and 71.5% (59.3- 80.1) respectively among 250 consecutively recruited patients. For HCV the PAF was 1.6% (95% CI -0.4 – 3.6) for cirrhosis and 4.8% (-0.1, 9.5) for HCC. Patients with HCC were diagnosed at an advanced stage with a median tumour size of 12.6cm and a median survival of 1.3 months. Six-month survival was 67% (59.0- 73.8) among patients with cirrhosis. Standardised HBsAg prevalence in serosurvey participants born prior to, and after HBV vaccine introduction, was 5.1% (95% CI 4.3- 6.1) and 0.3% (95% CI 0.1- 0.6) respectively. Three-dose vaccination coverage was 97.4% (1141/1171) among 1171/2085 children aged ≤10 years with known vaccine status. By comparison of participants born 5 years before and after vaccine introduction, vaccine impact was 95.9% (95% CI 70.6- 99.4). Treatment eligibility was assessed in 94/150 HBsAg positive people aged ≥16 years from the serosurvey, of whom 24/93 (26%) were HIV positive, and 16/24 (67%) were receiving antiretroviral therapy containing tenofovir, with HBV DNA suppression. Among 69 HIV-negative HBsAg positive individuals, 3,6 and 9% were eligible for HBV treatment by WHO, EASL and AASLD criteria respectively. Standardised HCV Ag/Ab prevalence was 0.78% (95% CI 0.46- 1.33) and HCV RNA prevalence was 0.18% (95% CI 0.06- 0.53). HCV Ag/Ab positive individuals were older than the general population but no differences in sex, educational, employment or marital status were observed. In an urban township in Malawi, HBV prevalence was intermediate at 5.1% among unvaccinated adults. Infant HBV vaccination was associated with a vaccine impact of 96%. Among HBsAg-positive adults, one quarter were HIV-positive and 3-9% of HIV-negative adults were eligible for antiviral therapy. Estimated population HCV RNA prevalence was 0.2%. Future prevalence studies should sample rural communities and specific risk groups. HCC is diagnosed at an advanced stage with a poor prognosis in Malawi, and HBV is an important cause. The burden of HBV and HCV associated liver disease represents both a challenge, and an opportunity to implement public health treatment programmes to reverse rising liver-related mortality in Southern Africa

Antibody mediated cellular phagocytosis in Hepatitis C and SARS-CoV-2 infections

Fc-mediated effector antibody functions including antibody-dependent cellular phagocytosis (ADCP), antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent complement deposition (ADCD), and antibody-dependent respiratory burst (ADRB) have been recognised to play a key role in antiviral immunity. Among these effector functions, ADCP alone or together with neutralisation function was shown to correlate with immune protection against several RNA viruses. However, methods that comprehensively study ADCP in HCV and SARS-CoV-2 using whole patient plasma are unavailable thereby precluding understanding to its role in the immunopathogenesis of these diseases. To address these, a robust high throughput flow cytometry-based ADCP assay was developed using THP-1 monocyte cell line as effector cells. This easy-to-use assay was then used to characterise ADCP in patients with HCV and SARS-CoV-2 infections. In patients with chronic HCV infection there was higher envelope 2 (E2) antibody titres while patients that cleared the virus produced antibodies with higher affinities. ADCP function was significantly higher in patients with chronic diseases than clearers and strongly correlated with antibody titre and neutralisation function. Multiple regression analysis showed that anti-E2 IgG is the most important variable for predicting ADCP regardless of disease severity, sex or age. Longitudinal study over 14 months showed anti-E2 antibody titres and ADCP function was maintained in both chronically infected patients and those who cleared the virus while there were variable changes in antibody affinities. In COVID-19, patients with acute disease mounted ADCP early as 10 days after symptom onset, primarily driven by heat labile components in the plasma. In convalescent patients, increased ADCP response significantly correlated with high anti-Spike IgG titres, older age, neutralisation and severe disease. Multiple regression analysis showed that anti-Spike antibody titre was the most important variable for predicting high ADCP. Longitudinal study over 12 months showed an increase in plasma antibody affinity and preservation of ADCP and neutralisation functions despite a decline in the anti-Spike IgG titres by >90%. Collectively, anti-E2 and anti-Spike antibody titres in plasma were the most important predictors of ADCP and neutralisation functions in HCV and SARS-CoV-2 infections respectively. Patients with chronic HCV infection showed higher ADCP when compared to clearers and there was a positive correlation between disease severity and ADCP in SARS-CoV-2 infection. Antibody titres in patients with HCV were maintained longitudinally together with ADCP while changes in affinities of the antibodies were variable. By contrast, in COVID-19 affinities increased overtime while. It is therefore likely preservation of ADCP function in HCV is due maintenance of high antibody titres while in COVID-19 it is due to the improvement in the quality of the antibodies

Characterising the B-cell response to Hepatitis C virus infection in patient cohorts: impact on clinical outcomes and implications for vaccine design

Hepatitis C virus (HCV) infection is one of the major causes of liver morbidity and mortality worldwide. While effective therapies are now available, if eradication of this virus is to be achieved globally, an effective vaccine is still necessary. During hepatitis C virus (HCV) infection, broadly neutralizing antibody (bNAb) responses targeting E1E2 envelope glycoproteins are generated in many individuals. It is unclear if these antibodies play a protective or a pathogenic role during chronic infection or if they could prevent infection or reinfection with the virus. I investigated the presence and clinical associations of bNAb responses in three cohorts of individuals infected with or exposed to HCV infection. One with chronic HCV infection at differing disease states, one with chronic HCV infection at an early disease state and one group of individuals at high risk of HCV exposure who remained uninfected by conventional testing. I also studied bNAb responses in an individual from a HCV-HIV co-infected cohort who experienced spontaneous clearance of HCV after a post-therapy relapse (‘secondary spontaneous clearance’). I found a proportion of individuals when exposed to or infected with HCV produce a polyclonal bNAb response which may contribute to viral clearance in some cases. Host genetics and the ability to target multiple neutralising epitopes on the envelope protein are associated with such responses, although resistance mutations to bNAbs do exist in vivo. The presence of bNAbs is associated with lower levels of liver fibrosis. Using next generation sequencing technology in the study of B cell receptors in HCV infection revealed subtle changes in the B cell repertoire on HCV infection, this technology may be used in future to gain insight into the generation of bNAb responses

Epidemiology of Injury in English Women's Super league Football: A Cohort Study

INTRODUCTION: The epidemiology of injury in male professional football has been well documented (Ekstrand, Hägglund, & Waldén, 2011) and used as a basis to understand injury trends for a number of years. The prevalence and incidence of injuries occurring in womens super league football is unknown. The aim of this study is to estimate the prevalence and incidence of injury in an English Super League Women’s Football squad. METHODS: Following ethical approval from Leeds Beckett University, players (n = 25) signed to a Women’s Super League Football club provided written informed consent to complete a self-administered injury survey. Measures of exposure, injury and performance over a 12-month period was gathered. Participants were classified as injured if they reported a football injury that required medical attention or withdrawal from participation for one day or more. Injuries were categorised as either traumatic or overuse and whether the injury was a new injury and/or re-injury of the same anatomical site RESULTS: 43 injuries, including re-injury were reported by the 25 participants providing a clinical incidence of 1.72 injuries per player. Total incidence of injury was 10.8/1000 h (95% CI: 7.5 to 14.03). Participants were at higher risk of injury during a match compared with training (32.4 (95% CI: 15.6 to 48.4) vs 8.0 (95% CI: 5.0 to 10.85)/1000 hours, p 28 days) of which there were three non-contact anterior cruciate ligament (ACL) injuries. The epidemiological incidence proportion was 0.80 (95% CI: 0.64 to 0.95) and the average probability that any player on this team will sustain at least one injury was 80.0% (95% CI: 64.3% to 95.6%) CONCLUSION: This is the first report capturing exposure and injury incidence by anatomical site from a cohort of English players and is comparable to that found in Europe (6.3/1000 h (95% CI 5.4 to 7.36) Larruskain et al 2017). The number of ACL injuries highlights a potential injury burden for a squad of this size. Multi-site prospective investigations into the incidence and prevalence of injury in women’s football are require

Ultrasensitive detection of toxocara canis excretory-secretory antigens by a nanobody electrochemical magnetosensor assay.

peer reviewedHuman Toxocariasis (HT) is a zoonotic disease caused by the migration of the larval stage of the roundworm Toxocara canis in the human host. Despite of being the most cosmopolitan helminthiasis worldwide, its diagnosis is elusive. Currently, the detection of specific immunoglobulins IgG against the Toxocara Excretory-Secretory Antigens (TES), combined with clinical and epidemiological criteria is the only strategy to diagnose HT. Cross-reactivity with other parasites and the inability to distinguish between past and active infections are the main limitations of this approach. Here, we present a sensitive and specific novel strategy to detect and quantify TES, aiming to identify active cases of HT. High specificity is achieved by making use of nanobodies (Nbs), recombinant single variable domain antibodies obtained from camelids, that due to their small molecular size (15kDa) can recognize hidden epitopes not accessible to conventional antibodies. High sensitivity is attained by the design of an electrochemical magnetosensor with an amperometric readout with all components of the assay mixed in one single step. Through this strategy, 10-fold higher sensitivity than a conventional sandwich ELISA was achieved. The assay reached a limit of detection of 2 and15 pg/ml in PBST20 0.05% or serum, spiked with TES, respectively. These limits of detection are sufficient to detect clinically relevant toxocaral infections. Furthermore, our nanobodies showed no cross-reactivity with antigens from Ascaris lumbricoides or Ascaris suum. This is to our knowledge, the most sensitive method to detect and quantify TES so far, and has great potential to significantly improve diagnosis of HT. Moreover, the characteristics of our electrochemical assay are promising for the development of point of care diagnostic systems using nanobodies as a versatile and innovative alternative to antibodies. The next step will be the validation of the assay in clinical and epidemiological contexts