Consistent sets of estimates for regressions with correlated or uncorrelated measurement errors in arbitrary subsets of all variables

Statistical Methods

Die interpretasiereël in die Suid-Afrikaanse kontraktereg (Deel 1)

The parol evidence rule in the South African law of contract consists of two different subrules. The one subrule deals with the extent to which a written contract may be regarded as the sole memorial of its terms and will be referred to as the “integration rule” in this article. Closely related to the integration rule is the so-called “interpretation rule”. The narrow definition of this rule entails that no evidence may be adduced to alter the clear and unambigious meaning of a written or verbal agreement. There is, however, also a wider definition that may be attributed to the interpretation rule, namely that it entails when and to what extent extrinsic evidence may be adduced to explain or alter the wording of a contract. In the past decades, there has been a development in the application of the interpretation rule in the South African law of contract from a strict formalistic textual approach to a more liberal contextual approach in terms of which more extrinsic evidence is allowed in order to interpret the written contract between the parties. In the first part of this article, the subjective and objective approaches to interpretation will be contrasted and the historical background of the interpretation rule will be briefly discussed. There will also be a critical analysis of the development and current application of the interpretation rule in the South African law of contract

Die interpretasiereël in die Suid-Afrikaanse kontraktereg – Deel Twee

In the first part of this article (that appeared in the June 2016 issue of this journal), the author analysed the development and current application of the interpretation rule in the South African law of contract. In the second part of this article, the author investigates in detail whether the current application of the interpretation rule is in line with the South African contractual liability approaches. The basis of contractual liability is briefly examined and how this concept is expressed as the common intention of the parties when a contract is entered into. Finally, the reasons for the existence of the application of the interpretation rule are critically investigated. It is argued that, although there has been considerable progress in terms of the admission of extrinsic evidence in the interpretation of contracts in the South African law, there is still a large degree of confusion and the current application in terms of the admission of extrinsic evidence in the interpretation of contracts still falls short. It is, therefore, recommended that legislation seems to be the only workable solution to rectify the problems pertaining to the interpretation rule once and for all

Interface Friction Parameters for the Mathematical Modeling of Shell Structures with Infill

Thin metal or reinforced concrete shells with granular infill structures are considered in this article. These structures are massive and they are used as support for the construction of berthing quays, piers, artificial islands, shore protection, and other structures of coastal infrastructure. It is more convenient to use the thin shell structures during the development of the Arctic shelf, because it is possible to install them from the ice side. In addition, it is possible to enhance the technology and install thin shells with infill on deeper solid foundation layers. A mathematical model for the stresses on a compressible foundation soil in front of a thin cylindrical shell with infill due to the eccentric loading is developed. A modeling and experimental determination of the interface strength of the contact surface between the infill and the inner surface of the shell is proposed. The details of the construction stages and testing of the physical model used for the experiments are discussed. The effects of the interface friction on the shell behavior and on the foundation stresses in front of the wall are investigated. The influence of parameters affecting the interaction between the soil infill and the inner surface of the shell material is determined. It is based on a comparison of experimental results with calculations performed using the proposed mathematical model. The obtained parameters and proposed methods can be used in numerical simulations using the finite element method to analyze and design the thin shell structures with soil infill. The findings of the study and proposed methods can also be applied to the thin shell structures used in other facilities such as hydraulic, industrial, civil, and transportation

Resident satisfaction as a project quality measure : the case of Nova Vida housing project, Angola

Towards the end of the 1975-2002 civil war, Luanda, the capital of Angola, experienced unprecedented urban growth. The pressure to reduce the housing backlog gave rise to large scale governmental residential development initiatives such as the Nova Vida housing project. Although the project experienced minor cost and schedule overruns the key question remains as to whether or not the project met the desired quality parameters in terms of resident satisfaction. As part of overall project quality performance measurement and continuous improvement cycle procedures, a post-project evaluation was done to investigate the level of satisfaction of the Nova Vida residents with their homes. A questionnaire was distributed among the Nova Vida residents measuring four factors namely (i) house design and architecture, (ii) house functionality, (iii) accessibility, and (iv) neighbourhood and community amenities. From the results it was possible to assess that the main concerns related to design, planning and urban management of infrastructure, public services and utilities. In general dissatisfaction is significantly higher for apartment residents than for house residents. The objective of providing safe, practical and comfortable living space was achieved. The results provided insight into the experiences of the Nova Vida occupants and are valuable input towards improving the planning, design and quality of future government housing projects.http://www.journals.co.za/ej/ejour_jcman.htmlai201

Late Ediacaran Redox Stability and Metazoan Evolution

The Neoproterozoic arrival of animals fundamentally changed Earth's biological and geochemical trajectory. Since the early description of Ediacaran and Cambrian animal fossils, a vigorous debate has emerged about the drivers underpinning their seemingly rapid radiation. Some argue for predation and ecology as central to diversification, whereas others point to a changing chemical environment as the trigger. In both cases, questions of timing and feedbacks remain unresolved. Through these debates, the last fifty years of work has largely converged on the concept that a change in atmospheric oxygen levels, perhaps manifested indirectly as an oxygenation of the deep ocean, was causally linked to the initial diversification of large animals. What has largely been absent, but is provided in this study, is a multi-proxy stratigraphic test of this hypothesis. Here, we describe a coupled geochemical and paleontological investigation of Neoproterozoic sedimentary rocks from northern Russia. In detail, we provide iron speciation data, carbon and sulfur isotope compositions, and major element abundances from a predominantly siliciclastic succession (spanning>1000 m) sampled by the Kel'tminskaya-1 drillcore. Our interpretation of these data is consistent with the hypothesis that the $pO_2$ threshold required for diversification of animals with high metabolic oxygen demands was crossed prior to or during the Ediacaran Period. Redox stabilization of shallow marine environments was, however, also critical and only occurred about 560 million years ago (Ma), when large motile bilaterians first enter the regional stratigraphic record. In contrast, neither fossils nor geochemistry lend support to the hypothesis that ecological interactions altered the course of evolution in the absence of environmental change. Together, the geochemical and paleontological records suggest a coordinated transition from low oxygen oceans sometime before the Marinoan (~635 Ma) ice age, through better oxygenated but still redox-unstable shelves of the early Ediacaran Period, to the fully and persistently oxygenated marine environments characteristic of later Ediacaran successions that preserve the first bilaterian macrofossils and trace fossils.Earth and Planetary SciencesOrganismic and Evolutionary Biolog

Interventions addressing the adolescent HIV continuum of care in South Africa: a systematic review and modified Delphi analysis

INTRODUCTION: Compared with adults, adolescents in South Africa have larger gaps at each step of the HIV continuum of care resulting in low levels of viral suppression. METHODS: We conducted a systematic review and modified Delphi analysis of interventions addressing the HIV continuum of care for adolescents in South Africa. We searched PubMed, Science Direct, and Google Scholar and online conference proceedings from the International AIDS Society, the International AIDS Conference, and the Conference on Retrovirology and Opportunistic Infections from 1 January 2010 to 30 September 2020. We then conducted a modified Delphi analysis with 29 researchers involved in the National Institutes of Health's Fogarty International-supported Adolescent HIV Implementation Science Alliance-South Africa to evaluate interventions for efficacy, feasibility and potential for scale-up. RESULTS: We identified nine initial published articles containing interventions addressing the adolescent HIV continuum of care in South Africa, including five interventions focused on HIV diagnosis, two on antiretroviral therapy adherence and two on retention in care. No studies addressed linkage to care or transition from paediatric to adult care. Two studies discussed intervention costs. In-home and HIV self-testing, community-based adherence support, and provision of adolescent-friendly services were the most impactful and scalable interventions addressing the adolescent HIV continuum of care. CONCLUSION: Future interventions should work comprehensively across the adolescent HIV continuum of care and be tailored to the specific needs of adolescents

Mathematical Model of the Shell with the Infill for Retaining Structures

A description of finite element model and analysis of a shell with an infill is performed. A large diameter thin cylindrical shell structure with the edge leaning against compressible foundation soil is analyzed. Different materials are considered individually for the models of each structure shell and infill component (metal or reinforced concrete shell, and granular or elastic infill in a shell and foundation soil loaded by the structure). Contact conditions between 1) the infill and the shell’s inner surface and 2) between the foundation material and the shell edge are analyzed. An example of calculating strain conditions in the shell according to the proposed finite element model and tasks of its development process and specification are provided in this paper