Hydraulic and environmental design aspects of hard coastal structures - The example of stepped revetments

To continue safeguarding coastal communities and infrastructure in the face of climate change requires a range of coastal protection measures. Simultaneously, the greater awareness for sustainable development and the sense of urgency to preserve and restore the coastal environment, underline the importance of designing coastal protection measures sustainably. Hard coastal structures are effective coastal protection measures against wave overtopping and flooding, as they form physical barriers against waves. However, the effects of hard structures on hydrodynamics, sediment dynamics and habitats, bring unintended negative changes to the environment. The first part of this dissertation critically discusses the use of hard coastal structures and their environmental impacts. To minimise the environmental impacts of hard coastal structures or create new ecosystem services, environmental aspects should be incorporated in standard coastal engineering practice from the earliest design stages. Based on examples and recommendations in literature, this dissertation provides guidance on environmental aspects to be considered in the design of hard coastal structures to increase their sustainability, i.e. consider future environmental, social and economic needs. The second part of this dissertation develops recommendations for the design of sustainable hard coastal structures, with the example of stepped revetments. Stepped revetments reduce wave overtopping effectively in comparison to smooth dikes, as their steps dissipate energy as waves interact with the structure. In addition to their primary function of ensuring coastal safety, stepped revetments offer opportunities for ecological enhancement and social benefits. The multi-functionality of stepped revetments make these structures especially suitable in urban and touristic settings. This dissertation improves design recommendations for stepped revetments by identifying environmental design aspects and improving design formulae for their hydraulic responses (wave reflection, wave run-up and wave overtopping). Environmental design aspects are identified based on literature and include suggested nature-based adaptations to stepped revetment designs. For instance, the vertical and horizontal step surfaces of stepped revetments provide areas here roughness and surface complexity can be maximised to increase habitat variety and promote biodiversity. Additionally, their steps could be adapted to mimic habitats for intertidal organisms, e.g. by altering revetment steps to incorporate water retaining features like rock pools. The feasibility and success of these nature-based adaptations are highly dependent on the local environmental conditions, including hydrodynamics. With knowledge of environmental design aspects, coastal engineers gain a greater interdisciplinary understanding, thereby facilitating sustainable designs. Hydraulic responses of stepped revetments are studied and analysed to improve and expand design recommendations for wave overtopping, wave run-up and wave reflection. In full-scale wave flume experiments, two stepped revetment cross-sections, each with a slope of 1:3, were studied. The first cross-section had uniformstep heights of 0.50 m, which was selected to add the secondary function of providing seating, i.e. serve as a bench. For the second cross-section, uniform step heights of 0.17 m were selected, as a typical height for walking up a staircase. Wave heights (Hm0) up to 1 m and wave periods (Tm−1,0) up to 6.5 s were generated. Based on the measurements of the physical model tests, empirical formulae were developed for estimating wave overtopping, wave run-up and wave reflection. The tested stepped revetments effectively reduced wave overtopping in comparison to smooth dikes, resulting in influence factors for roughness (γf ) between 0.43 and 0.73. Compared to smooth dikes, the energy dissipation of the revetment stairs reduces wave reflection and wave run-up. Within the tested range of boundary conditions, the stepped revetment with large steps (Sh=0.50 m) proved more effective in dissipating energy and reducing wave overtopping (0.43 ≤ γf ≤ 0.54). The higher effectiveness of the large steps is also confirmed with the measured wave reflection. Wave conditions were repeated for the large (Sh = 0.50m) and small steps (Sh = 0.17m) showing that reflection coefficients were 55 % higher at the small steps. Individual overtopping volumes at the tested stepped revetments are described by a two-parameter Weibull distribution, revealing a higher median shape factor (b=1.63) for stepped revetments compared to breakwaters, smooth dikes or vertical walls. The wave flume tests provide greater insight in the functioning of stepped revetments and enable the quantification of the hydraulic responses of stepped revetments. The experimental work presented in this dissertation provides one of the first investigations into the hydraulic responses of stepped revetments at full scale. Compared to small-scale wave run-up and overtopping measurements, this study reveals that hydraulic responses measured in small scale are likely affected by scale effects. Small-scale studies overestimate the wave overtopping reduction (γf ) by 2-31 % and underestimate relative wave run-up heights (Ru2%/Hm0) by 31-51 %. As a result, basing the designs of stepped revetments on small-scale measurements could therefore lead to unsafe designs. The gained knowledge on environmental aspects and hydraulic responses (wave reflection, run-up and overtopping) improves design recommendations for stepped revetments with regard to coastal safety and sustainability. In terms of coastal safety, the presented full-scale model tests provide reliable design recommendations that are not affected by scale. In terms of sustainability, the dissertation provides a review of environmental design aspects of coastal structures in general, and stepped revetments in particular. Hence, this dissertation contributes to recommendations for designing sustainable coastal structures

The advertising of nutritional supplements in South African women’s magazines: a descriptive survey

Objective: Nutritional supplements are inadequately regulated in South Africa. These types of products are increasingly advertised and the advertisements frequently contain health claims. Because advertisements play a considerable role in informing potential consumers, it is crucial that information about supplements in advertisements is accurate. A survey was carried out to determine the extent to which health claims are made in nutritional supplement advertisements and to describe the appropriateness of the research cited within the advertisements in support of the health claims.Design: The design was a descriptive survey.Method: The five women’s magazines with the highest circulation figures in South Africa in July 2010 were identified by the Audit Bureau of Circulations of South Africa as Cosmopolitan, Finesse, Move!, Rooi Rose and Sarie. Issues of these magazines were obtained during the period from September 2010 to August 2011. Pre-specified eligibility criteria were used to identify suitable advertisements and to determine the percentage of nutritional supplements about which health claims were made. The percentage of these supplements for which research was cited in support of the claims was also determined, and the level and appropriateness of the cited research, described.Results: In total, 486 eligible advertisements were identified which referred to 158 nutritional supplements. Of these, 137 (86.7%) made health claims and 9 of the 137 (6.6%) cited research to support their claims. The cited research was judged to be largely inappropriate based on study design and/or the characteristics of the study.Conclusion: South Africans should be wary of advertisements that make claims about the health benefits and safety of nutritional supplements. Regulation of the advertising of nutritional supplements is urgently needed.Keywords: dietary supplements, health claims, regulation, advertising, evidence based health car

Pycnogenol for the treatment of chronic disorders : a systematic review

Thesis (MNutr)-- Stellenbosch University, 2011.ENGLISH ABSTRACT: Background: Oxidative stress has been implicated in the development of a number of conditions including amongst others cancer, arthritic disorders and cardiovascular disease. Pycnogenol is a herbal dietary supplement derived from French maritime pine bark extract. Pycnogenol is standardised to contain 70 ± 5% procyanidin which is a powerful antioxidant. Pycnogenol is marketed as a supplement for preventing or treating a wide range of chronic conditions. Although several randomised controlled trials of Pycnogenol have been conducted to date, this evidence has not yet been systematically reviewed. Objectives: The aim was to carry out a systematic review in order to assess the efficacy and safety of Pycnogenol for the treatment of chronic disorders. Search methods The electronic databases CENTRAL (until 18 September 2010), MEDLINE (until 18 September 2010) and EMBASE (until 13 October 2010) were searched, as well as three trial registries. Furthermore the manufacturer of Pycnogenol was contacted and bibliographies of included studies were hand-searched. Selection criteria: Randomised controlled trials (RCTs) evaluating the effectiveness of Pycnogenol in adults or children with any chronic disorder were included. The primary outcomes were any clinical outcomes directly related to the disorder (stratified as participant- and investigator-reported) as well as all-cause mortality. Adverse events and biomarkers of oxidative stress were also assessed. Data collection and analysis: Two authors independently assessed trial eligibility, extracted all data and judged methodological quality. A third author additionally extracted information on outcomes and results. With two exceptions, results for outcomes across studies could not be pooled mainly due to poor quality reporting. Study authors were contacted for additional information. Results: This review includes 15 RCTs with a total of 791 participants that have evaluated Pycnogenol for the treatment of seven different chronic disorders. The disorders included asthma (2 studies; N = 86), attention deficit hyperactivity disorder (1 study; N = 61), chronic venous insufficiency (2 studies; N = 60), diabetes mellitus (4 studies; N = 201), erectile dysfunction (1 study; N = 21), hypertension (2 studies; N = 69) and osteoarthritis of the knee (3 studies; N = 293). Two of the studies were conducted exclusively in children; the others involved adults. Due to small sample size, limited numbers of trials per condition, variation in selected outcomes and outcomes measures and the risk of bias no definitive conclusions regarding the efficacy or safety of Pycnogenol are possible. Authors’ conclusions: Current evidence is insufficient to support Pycnogenol use for the treatment of any chronic disorder. Well designed, adequately powered trials are recommended to establish the value of this treatment.AFRIKAANSE OPSOMMING: Inleiding: Oksidatiewe stres blyk ’n rol te speel in die ontwikkeling van ’n verskeidenheid siektes onder andere kanker, artritis en kardiovaskulêre siektes. Pycnogenol, ‘n kruie-bevattende dieetaanvulling wat uit Franse denneboombas vervaardig word, is gestandaardiseer om 70 ± 5% prosianidien – ’n kragtige anti-oksidant – te bevat. Die produk word bemark om ‘n wye reeks chroniese siektes te voorkom of te behandel. Alhoewel daar tot op hede verskeie kliniese proewe op Pycnogenol uitgevoer is, is die uitkomstes nog nie met behulp van ‘n stelselmatiese oorsig geëvalueer nie. Doelwitte: Die doel van hierdie studie was om met behulp van ‘n stelselmatiese oorsig die doeltreffendheid en veiligheid van Pycnogenol ten opsigte van die behandeling van chroniese siektes te evalueer. Soektogstrategie: Die elektroniese databasisse CENTRAL (tot 18 September 2010), MEDLINE (tot 18 September 2010) en EMBASE (tot 13 Oktober 2010) is deursoek, asook drie registers met kliniese proewe. Verder is die vervaardiger van Pycnogenol gekontak en is daar met die hand deur bibliografieë van ingeslote studies gesif. Keuringskriteria: Ewekansige gekontroleerde proewe (RCT’s) is ingesluit waarin die effektiwiteit van Pycnogenol in volwassenes of kinders met enige chroniese siekte geëvalueer is. Enige kliniese uitkomste wat direk aan die chroniese siekte verwant is (gesorteer as deelnemer- of ondersoeker-gerapporteerde uitkomstes) asook mortaliteit (enige oorsake) is as die primêre uitkomstes ondersoek. Dataversameling en -ontleding: Twee navorsers het onafhanklik van mekaar proewe gekeur, alle relevante data onttrek en gehalte van die metodiek beoordeel. ‘n Derde navorser het die resultate van die uitkomstes bykomend onttrek. Met twee uitsonderings, kon resultate van uitkomstes van die verskillende ingeslote studies kon nie statisties saamgevoeg word nie, hoofsaaklik as gevolg van swak rapportering. Skrywers van die ingeslote studies is in verband met die verlangde inligting gekontak. Resultate: Vyftien RCT’s met ‘n totaal van 791 deelnemers is ingesluit. In hierdie studies is Pycnogenol vir die behandeling van sewe verskillende chroniese siektes geëvalueer: asma (2 studies; N = 86), aandagafleibaarheid-hiperaktiwiteitsgebreksindroom (1 studie; N = 61), chroniese veneuse ontoereikendheid (2 studies; N = 60), diabetes mellitus (4 studies; N = 201), erektiele disfunksie (1 studie; N = 21), hipertensie (2 studies; N = 69) en osteo-artritis van die knie (3 studies; N = 293). Twee van hierdie studies is uitsluitlik met kinders gedoen; die res was volwassenes. As gevolg van klein steekproewe, ‘n beperkte aantal studies per siekte, wisseling in uitkomstes en die risiko vir sydigheid kan geen definitiewe gevolgtrekking oor die doeltreffendheid en veiligheid van Pycnogenol gemaak word nie. Skrywers se gevolgtrekking: Tans is daar nie voldoende wetenskaplike bewyse om Pycnogenol-gebruik vir die behandeling van enige chroniese siekte aan te beveel nie. Goed ontwerpte proewe met ‘n voldoende aantal deelnemers word aanbeveel om die waarde van hierdie behandeling onomwonde vas te stel

Musikus gehuldig

De Villiers had a full life as an organist and composer especially involved with school and church.pdf file of article published in Huisgenoot of July 28, 1944.er2014-3pm2014-

A likelihood ratio analysis of digital phase modulation

Bibliography: p. 180-188.Although the likelihood ratio forms the theoretical basis for maximum likelihood (ML) detection in coherent digital communication systems, it has not been applied directly to the problem of designing good trellis-coded modulation (TOM) schemes. The remarkably simple optimal receiver of minimum shift keying (MSK) has been shown to result from the mathematical simplification of its likelihood ratio into a single term. The log-likelihood ratio then becomes a linear sum of metrics which can be implemented as a so-called simplified receiver, comprising only a few adders and delay elements. This thesis project investigated the possible existence of coded modulation schemes with similarly simplifying likelihood ratios, which would have almost trivially simple receivers compared to the Viterbi decoders which are typically required for maximum likelihood sequence estimation (MLSE). A useful notation, called the likelihood transform, was presented to aid the analysis of likelihood ratios. The work concentrated initially on computer-aided searches, first for trellis codes which may give rise to simplifying likelihood ratios for continuous phase modulation (CPM), and then for mathematical identities which may aid in the simplification of generic likelihood ratios for equal-energy modulation. The first search yielded no simplified receivers, and all the identities produced by the second search had structures similar to the likelihood ratio of MSK. These observations prompted a formal proof of the non-existence of simplified receivers which use information from more than two symbols in their observation period. This result strictly bounds the error performance that is possible with a simplified receiver. It was also proved that simplified receivers are only optimal for modulation schemes which use no more than two pairs of antipodal signals, and that only binary modulation schemes can have simplified receivers which use information from all the symbols in their observation period

Methods for Modelling Response Styles

Abstract Ratings scales are ubiquitous in empirical research, especially in the social sciences, where they are used for measuring abstract concepts such as opinion or attitude. Survey questions typically employ rating scales, for example when persons are asked to self-report their perceptions of films or their job satisfaction. Yet, using a rating scale is subjective. Some persons may use only the middle of the rating scale, whilst others choose to use only the extremes. Consequently, persons with the same opinion may very well answer the same survey question using different ratings. This leads to the response style problem: How can we take into account that different ratings can potentially have different meanings to different persons when analyzing such data? This dissertation makes methodological and empirical contributions towards modelling rating scale data while accounting for such differences in response styles. The general approach is to identify individuals in the data which exhibit similar response styles, and to extract substantive information only within such groups. These elements naturally lead to the synthesis of cluster analysis and dimensionality reduction methods. In order to identify these response styles, responses to multiple survey questions are used to assess within-subject rating scale usage. Both non-parametric and parametric approaches are formulated and studied, and accompanying open-source software implementations are made available. The added value of using the developed algorithms is illustrated by applying these to empirical data. Applications range from sensometrics and brand studies, to psychology and political science

Least-squares Bilinear Clustering of Three-way Data

__Abstract__ A least-squares bilinear clustering framework for modelling three-way data, where each observation consists of an ordinary two-way matrix, is introduced. The method combines bilinear decompositions of the two-way matrices into overall means, row margins, column margins and row-column interactions with clustering along the third way. Different clusterings are defined for each part of the decomposition, so that up to four different classifications are defined jointly. The computational burden is greatly reduced by the orthogonality of the bilinear model, such that the joint clustering problem reduces to separate ones which can be handled independently. Three of these sub-problems are specific cases of $k$-means clustering; a special algorithm is formulated for the row-column interactions, which are displayed in clusterwise biplots. The method is illustrated via two empirical examples and interpreting the interaction biplots are discussed

Constrained Dual Scaling for Detecting Response Styles in Categorical Data

Dual scaling is a multivariate exploratory method equivalent to correspondence analysis when analysing contingency tables. However, for the analysis of rating data different proposals appear in the dual scaling and correspondence analysis literature. It is shown here that a peculiarity of the dual scaling method can be exploited to detect differences in response styles. Response styles occur when respondents use rating scales differently for reasons not related to the questions, often biasing results. A spline-based constrained version of dual scaling is devised which can detect the presence of four prominent types of response styles, and is extended to allow for multiple response styles. An alternating nonnegative least squares algorithm is devised for estimating the parameters. The new method is appraised both by simulation studies and an empirical application

Constrained Dual Scaling for Detecting Response Styles in Categorical Data

Dual scaling (DS) is a multivariate exploratory method equivalent to correspondence analysis when analysing contingency tables. However, for the analysis of rating data, different proposals appear in the DS and correspondence analysis literature. It is shown here that a peculiarity of the DS method can be exploited to detect differences in response styles. Response styles occur when respondents use rating scales differently for reasons not related to the questions, often biasing results. A spline-based constrained version of DS is devised which can detect the presence of four prominent types of response styles, and is extended to allow for multiple response styles. An alternating nonnegative least squares algorithm is devised for estimating the parameters. The new method is appraised both by simulation studies and an empirical application