A possibilistic approach to diverse-stressor aquatic ecological risk estimation

A possibilistic approach to assess the risk of co-occurring stressors in an aquatic ecosystem based on the use of fuzzy sets is illustrated at the hand of a hypothetical case study. There are two aspects of importance: a fuzzy stressor response relationship where the response may have reference to a lower level end-point, and a rule-based inference model relating the occurrence of low-level stressors to a high-level ecological goal such as sustainability. The stressor-response is expressed as a conditional possibility. The possibility and necessity measures of the disjunctive composition of the stressor-response with the possibility distribution of the stressors yield an estimate of the ecological risk. Such a possibilistic approach may well serve as a screening procedure in multiple stressor resource management when only qualitative risk assessments are needed. WaterSA Vol.27(3) 2001: 293-30

Developing non-cognitive skills in part-time students at a South African university: Overcoming negativity and supporting behavioural change

This paper reports on the findings of an intervention aimed at assisting a group of thirty-one part-time students registered for a third year Management Accounting and Finance course to develop a range of non-cognitive skills that have been shown to positively impact academic behaviour. In addition to facilitating the teaching and learning of academic content, lecturers introduced students to academic mindsets, academic behaviours, learning strategies and social skills through role-plays and practical demonstrations. The intervention also strove to influence the context in which students learned in order to positively influence the attitudes of the students towards the course and to motivate them to acquire and practice behaviours that would support their learning. The intervention involved two action research cycles in which the researchers were able to reflect on the effectiveness of the various approaches used to encourage behaviour change and the acquisition of new skills. The findings of the study indicate that the intervention was successful in developing a range of non-cognitive attitudes, strategies and behaviours in students, with most of the cohort reporting positive changes in attitude towards their studies and the belief that academic success was indeed possible

Quasi-Orthogonality of Some Hypergeometric and qq-Hypergeometric Polynomials

We show how to obtain linear combinations of polynomials in an orthogonal sequence $\{P_n\}_{n\geq 0}$, such as $Q_{n,k}(x)=\sum\limits_{i=0}^k a_{n,i}P_{n-i}(x)$, $a_{n,0}a_{n,k}\neq0$, that characterize quasi-orthogonal polynomials of order $k\le n-1$. The polynomials in the sequence $\{Q_{n,k}\}_{n\geq 0}$ are obtained from $P_{n}$, by making use of parameter shifts. We use an algorithmic approach to find these linear combinations for each family applicable and these equations are used to prove quasi-orthogonality of order $k$. We also determine the location of the extreme zeros of the quasi-orthogonal polynomials with respect to the end points of the interval of orthogonality of the sequence $\{P_n\}_{n\geq 0}$, where possible

Evaluation of soil and groundwater remediation strategies for decommissioning nuclear facilities on the basis of sustainability assessment incorporating net present value

The decommissioning of nuclear facilities and remediation of radiological and non radiological contaminated land is currently being undertaken at some Magnox nuclear licensed sites in the UK. Sustainability needs to be considered so that well balanced remediation strategies are chosen that accommodate the long time frames decommissioning can take. Sustainable remediation options assessment involves selecting feasible soil and groundwater strategies to meet risk reduction goals whilst maximising the environmental, social and economic benefits. This study describes two Magnox nuclear decommissioning sites, Bradwell site in England and Chapelcross site in Scotland. A conceptual site model (CSM) was developed for land and groundwater contamination at each site. Identification and screening of suitable remediation strategies was followed by a sustainability assessment. The Sustainable Remediation Forum UK (SuRF UK) framework was used, incorporating a Net Present Value (NPV) for the economic element and a Multi Criteria Decision Analysis (MCDA) was applied using a software tool called Hiview. The exercise showed that feasible soil and groundwater remediation strategies were identified using the SuRF UK Framework and Hiview MCDA soft-ware. The process showed for complex sites it can be timely developing a detailed CSM but it makes screening remediation strategies a much easier process although detailed understanding of techniques is required. The study has shown that a cost estimate can take longer than a sustainability assessment, due to there being limited case studies and examples available within literature due to commercial sensitivity. This is the first time the Sustainable Remediation Forum UK (SuRF UK) Framework has been applied using Hiview MCDA software to two nuclear decommissioning sites. It is also the first example of applying the SuRF UK Framework to remediation options assessment for radioactive contaminated land. The process showed scoring as a single assessor can introduce bias and that stakeholder involvement for weighting the importance of indicators would be recommended in order to get a true representation. Applying sensitivity analysis and testing alterations in weightings is crucial in ensuring that an assessment is robust. Sites with site specific quantitative data resulted in a more robust assessment and remediation strategies which had the ability to be flexible long term were the more sustainable options

ACUTE DESTRUCTION BY HUMORAL ANTIBODY OF RAT SKIN GRAFTED TO MICE : THE ROLE OF COMPLEMENT AND POLYMORPHONUCLEAR LEUKOCYTES

A study has been made of the roles played by complement and polymorphonuclear leukocytes (PMN) in the acute destruction of xenografts of rat skin that follows injection of their hosts with antisera specifically reactive with graft antigens. The rat skin was grafted onto mice whose immune responses were suppressed by removal of the thymus and a brief course of treatment with rabbit antimouse lymphocyte serum. At about 2 wk after grafting the mice were injected intravenously or intraperitoneally with mouse antirat serum (MARS). This time interval was chosen because it avoided the complications that might be associated with either the process of healing in or with incipient rejection. Signs of graft damage were evident as early as 10 min after the injection of MARS, and in most animals so injected the grafts were completely destroyed within 24–48 h. The role of complement (C) in this acute destructive process is indicated by the results of three lines of experimentation. (a) Non-C-fixing antibodies or antibody fragments failed to cause damage to the grafts. Indeed, both chicken antirat serum and F(ab')2 fragments from rabbit antirat serum completely protected the grafts against the effects of MARS that was administered 24 h later. (b) When mice were depleted of hemolytic C by treatment with cobra venom factor or heat-aggregated gamma globulin, the damage caused by MARS was greatly reduced or completely inhibited. (c) In mice with a genetically determined absence of C5 much greater quantities of MARS were required to cause graft damage; the tempo of the destructive process was consistently slower; and a greater number of grafts recovered from the initial inflammatory process than was the case for animals with an intact complement system. The participation of PMN in serum-mediated destruction of grafts was initially suggested by the results of microscope examination of fixed tissues. The essential role of these cells in the process is indicated by the failure of MARS to cause tissue damage in mice whose circulating PMN have been reduced to very low levels by treatment with nitrogen mustard or more specifically with an anti-PMN serum. The absence of tissue damage when circulating PMN are reduced but C levels are normal suggests that C-mediated cytolysis is unimportant in graft destruction and that the role of C lies in its ability to generate chemotactic factors. The latter may then attract the PMN that provide mediators of tissue damage

Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water

Background While previous research has suggested that there is an association between fluoride ingestion and the incidence of hypothyroidism, few population level studies have been undertaken. In England, approximately 10% of the population live in areas with community fluoridation schemes and hypothyroidism prevalence can be assessed from general practice data. This observational study examines the association between levels of fluoride in water supplies with practice level hypothyroidism prevalence. Methods We used a cross-sectional study design using secondary data to develop binary logistic regression models of predictive factors for hypothyroidism prevalence at practice level using 2012 data on fluoride levels in drinking water, 2012/2013 Quality and Outcomes Framework (QOF) diagnosed hypothyroidism prevalence data, 2013 General Practitioner registered patient numbers and 2012 practice level Index of Multiple Deprivation scores. Findings We found that higher levels of fluoride in drinking water provide a useful contribution for predicting prevalence of hypothyroidism. We found that practices located in the West Midlands (a wholly fluoridated area) are nearly twice as likely to report high hypothyroidism prevalence in comparison to Greater Manchester (non-fluoridated area). Interpretation In many areas of the world, hypothyroidism is a major health concern and in addition to other factors—such as iodine deficiency—fluoride exposure should be considered as a contributing factor. The findings of the study raise particular concerns about the validity of community fluoridation as a safe public health measure

Recent HIV prevalence trends among pregnant women and all women in sub-Saharan Africa: implications for HIV estimates

OBJECTIVES: National population-wide HIV prevalence and incidence trends in sub-Saharan Africa (SSA) are indirectly estimated using HIV prevalence measured among pregnant women attending antenatal clinics (ANC), among other data. We evaluated whether recent HIV prevalence trends among pregnant women are representative of general population trends. DESIGN: Serial population-based household surveys in 13 SSA countries. METHODS: We calculated HIV prevalence trends among all women aged 15–49 years and currently pregnant women between surveys conducted from 2003 to 2008 (period 1) and 2009 to 2012 (period 2). Log-binomial regression was used to test for a difference in prevalence trend between the two groups. Prevalence among pregnant women was age-standardized to represent the age distribution of all women. RESULTS: Pooling data for all countries, HIV prevalence declined among pregnant women from 6.5 [95% confidence interval (CI) 5.3–7.9%] to 5.3% (95% CI 4.2–6.6%) between periods 1 and 2, whereas it remained unchanged among all women at 8.4% (95% CI 8.0–8.9%) in period 1 and 8.3% (95% CI 7.9–8.8%) in period 2. Prevalence declined by 18% (95% CI −9–38%) more in pregnant women than nonpregnant women. Estimates were similar in Western, Eastern, and Southern regions of SSA; none were statistically significant (P > 0.05). HIV prevalence decreased significantly among women aged 15–24 years while increasing significantly among women 35–49 years, who represented 29% of women but only 15% of pregnant women. Age-standardization of prevalence in pregnant women did not reconcile the discrepant trends because at older ages prevalence was lower among pregnant women than nonpregnant women. CONCLUSION: As HIV prevalence in SSA has shifted toward older, less-fertile women, HIV prevalence among pregnant women has declined more rapidly than prevalence in women overall. Interpretation of ANC prevalence data to inform national HIV estimates should account for both age-specific fertility patterns and HIV-related sub-fertility

South Africans’ understanding of and response to the COVID-19 outbreak: An online survey

Background. The COVID-19 outbreak is in an accelerating phase, and South Africa (SA) has had the highest number of documented cases during the early phase of the pandemic in sub-Saharan Africa.Objectives. To assess South Africans’ understanding of and response to COVID-19 during the first week of the country’s lockdown period.Methods. An online survey was conducted in SA from 27 March to 2 April 2020. The survey was distributed widely among several websites and social media networks, including on a data-free platform. Descriptive statistics of knowledge, risk perception, access to and trust in information sources, and public and media opinions were calculated. Estimates were benchmarked to the 2019 national adult population estimates.Results. Of the 55 823 participants, the majority (83.4%) correctly identified the main symptoms of COVID-19. Over 90% had correct knowledge of the incubation period, with lower rates for 18 - 29-year-olds. Knowledge of symptoms and the incubation period varied significantly by population group (p<0.001), dwelling type (p<0.001) and sex (p<0.001). A quarter (24.9%) perceived themselves as at high risk of contracting COVID-19. Risk perception varied by age, population group, employment status and dwelling type (p<0.001). The most prevalent COVID-19 information sources were government sources (72.9%), news websites/apps (56.3%), satellite television (51.6%) and local television (51.4%).Conclusions. Understanding knowledge, attitudes and behaviours of people facing the COVID-19 pandemic is crucial for guiding strategic policy. These findings provide public understanding of COVID-19 as the phases of the country-level epidemic progress, and also directly inform communication needs and gaps

Experimental and theoretical study of vibrations of a cantilevered beam using a ZnO piezoelectric sensor

Piezoelectric sensors can measure vibrations of solid structures very accurately. A model of a cantilevered beam, with a ZnO film on one side is presented. Both viscous and internal damping are considered. The output of the sensor is modeled and matched with experimental results by adjusting the damping parameters. A theoretical formulation for damage is introduced. Experimental results for a damaged beam confirm the shift in frequencies to lower values. The model is used to identify the extent of the damage