Gradient-only approaches to avoid spurious local minima in unconstrained optimization

We reflect on some theoretical aspects of gradient-only optimization for the unconstrained optimization of objective functions containing non-physical step or jump discontinuities. This kind of discontinuity arises when the optimization problem is based on the solutions of systems of partial differential equations, in combination with variable discretization techniques (e.g. remeshing in spatial domains, and/or variable time stepping in temporal domains). These discontinuities, which may cause local minima, are artifacts of the numerical strategies used and should not influence the solution to the optimization problem. Although the discontinuities imply that the gradient field is not defined everywhere, the gradient field associated with the computational scheme can nevertheless be computed everywhere; this field is denoted the associated gradient field. We demonstrate that it is possible to overcome attraction to the local minima if only associated gradient information is used. Various gradient-only algorithmic options are discussed. A salient feature of our approach is that variable discretization strategies, so important in the numerical solution of partial differential equations, can be combined with efficient local optimization algorithms.National Research Foundation (NRF)http://link.springer.com/journal/11081hb201

Biblical Theology of Life in the Old Testament

Life is a primary theme in Scripture, expressed in the rich diversity of the various books, corpora and genres of Scripture. Much has been published on what Scripture teaches about life and death. To date, however, no comprehensive biblical theology in which the concept of life is traced throughout the different books and corpora of the Old and New Testament has been published. It is this lacuna that this book aims to fill, assuming that such an approach can provide a valuable contribution to the theological discourse on life and related concepts. The primary aim of this book is to give an indication of the different nuances of the concept of life in the various books and corpora of the Old and New Testament by providing the reader with a book-by-book overview of the concept of life in Scripture. The secondary aim is to give an indication of the overall use and function of the concept of life in the Old Testament, the New Testament, and Scripture as a whole. The latter is provided by using the findings of the book-by-book overview of the concept of life in Scripture to draw the lines together

Southern African pasture and forage science entering the 21st century : past to present

Given the global challenges of mitigating and alleviating land degradation and ensuring food security, particularly through protein production, pasture and forage science together with rangeland science will remain imperative to sustainable livestock production systems. Recognising the scientific principles developed in this discipline the past 50 years and more in Southern Africa, customary to our diverse and unique environmental conditions will continue to guide and identify future research priorities. A journey from the past to the present can assist in avoiding reinvention and repetition of pasture research. This review highlights how research priorities have either remained the same over time or where research has received less or more priority. The review further illustrates that there has been more interest in species adaptation to drought, pasture and forage water relations, alternative pasture and forage species, and the combination of pasture species in the 21st century than in the 20th century. In conclusion, the soil–plant– livestock complex can serve as a conceptual basis for more effective research together with pasture breeding and nutrition. Finally, researching pasture and forage sciences in an inter- and multi-disciplinary manner clearly supports the principles of holism applied by General JC Smuts, one of the first pioneers of pasture and forage sciences.http://www.tandfonline.com/loi/tarf20hb2016Plant Production and Soil Scienc

Biblical Theology of Life in the Old Testament

Life is a primary theme in Scripture, expressed in the rich diversity of the various books, corpora and genres of Scripture. Much has been published on what Scripture teaches about life and death. To date, however, no comprehensive biblical theology in which the concept of life is traced throughout the different books and corpora of the Old and New Testament has been published. It is this lacuna that this book aims to fill, assuming that such an approach can provide a valuable contribution to the theological discourse on life and related concepts. The primary aim of this book is to give an indication of the different nuances of the concept of life in the various books and corpora of the Old and New Testament by providing the reader with a book-by-book overview of the concept of life in Scripture. The secondary aim is to give an indication of the overall use and function of the concept of life in the Old Testament, the New Testament, and Scripture as a whole. The latter is provided by using the findings of the book-by-book overview of the concept of life in Scripture to draw the lines together

Aquatic birds have middle ears adapted to amphibious lifestyles

Birds exhibit wide variation in their use of aquatic environments, on a spectrum from entirely terrestrial, through amphibious, to highly aquatic. Although there are limited empirical data on hearing sensitivity of birds underwater, mounting evidence indicates that diving birds detect and respond to sound underwater, suggesting that some modifications of the ear may assist foraging or other behaviors below the surface. In air, the tympanic middle ear acts as an impedance matcher that increases sound pressure and decreases sound vibration velocity between the outside air and the inner ear. Underwater, the impedance-matching task is reversed and the ear is exposed to high hydrostatic pressures. Using micro- and nano-CT (computerized tomography) scans of bird ears in 127 species across 26 taxonomic orders, we measured a suite of morphological traits of importance to aerial and aquatic hearing to test predictions relating to impedance-matching in birds with distinct aquatic lifestyles, while accounting for allometry and phylogeny. Birds that engage in underwater pursuit and deep diving showed the greatest differences in ear structure relative to terrestrial species. In these heavily modified ears, the size of the input areas of both the tympanic membrane and the columella footplate of the middle ear were reduced. Underwater pursuit and diving birds also typically had a shorter extrastapedius, a reduced cranial air volume and connectivity and several modifications in line with reversals of low-to-high impedance-matching. The results confirm adaptations of the middle ear to aquatic lifestyles in multiple independent bird lineages, likely facilitating hearing underwater and baroprotection, while potentially constraining the sensitivity of aerial hearing

HIV Testing and Treatment with the Use of a Community Health Approach in Rural Africa.

BACKGROUND: Universal antiretroviral therapy (ART) with annual population testing and a multidisease, patient-centered strategy could reduce new human immunodeficiency virus (HIV) infections and improve community health. METHODS: We randomly assigned 32 rural communities in Uganda and Kenya to baseline HIV and multidisease testing and national guideline-restricted ART (control group) or to baseline testing plus annual testing, eligibility for universal ART, and patient-centered care (intervention group). The primary end point was the cumulative incidence of HIV infection at 3 years. Secondary end points included viral suppression, death, tuberculosis, hypertension control, and the change in the annual incidence of HIV infection (which was evaluated in the intervention group only). RESULTS: A total of 150,395 persons were included in the analyses. Population-level viral suppression among 15,399 HIV-infected persons was 42% at baseline and was higher in the intervention group than in the control group at 3 years (79% vs. 68%; relative prevalence, 1.15; 95% confidence interval [CI], 1.11 to 1.20). The annual incidence of HIV infection in the intervention group decreased by 32% over 3 years (from 0.43 to 0.31 cases per 100 person-years; relative rate, 0.68; 95% CI, 0.56 to 0.84). However, the 3-year cumulative incidence (704 incident HIV infections) did not differ significantly between the intervention group and the control group (0.77% and 0.81%, respectively; relative risk, 0.95; 95% CI, 0.77 to 1.17). Among HIV-infected persons, the risk of death by year 3 was 3% in the intervention group and 4% in the control group (0.99 vs. 1.29 deaths per 100 person-years; relative risk, 0.77; 95% CI, 0.64 to 0.93). The risk of HIV-associated tuberculosis or death by year 3 among HIV-infected persons was 4% in the intervention group and 5% in the control group (1.19 vs. 1.50 events per 100 person-years; relative risk, 0.79; 95% CI, 0.67 to 0.94). At 3 years, 47% of adults with hypertension in the intervention group and 37% in the control group had hypertension control (relative prevalence, 1.26; 95% CI, 1.15 to 1.39). CONCLUSIONS: Universal HIV treatment did not result in a significantly lower incidence of HIV infection than standard care, probably owing to the availability of comprehensive baseline HIV testing and the rapid expansion of ART eligibility in the control group. (Funded by the National Institutes of Health and others; SEARCH ClinicalTrials.gov number, NCT01864603.)

High rates of viral suppression in adults and children with high CD4+ counts using a streamlined ART delivery model in the SEARCH trial in rural Uganda and Kenya.

INTRODUCTION: The 2015 WHO recommendation of antiretroviral therapy (ART) for all HIV-positive persons calls for treatment initiation in millions of persons newly eligible with high CD4+ counts. Efficient and effective care models are urgently needed for this population. We evaluated clinical outcomes of asymptomatic HIV-positive adults and children starting ART with high CD4+ counts using a novel streamlined care model in rural Uganda and Kenya. METHODS: In the 16 intervention communities of the HIV test-and-treat Sustainable East Africa Research for Community Health Study (NCT01864603), all HIV-positive individuals irrespective of CD4 were offered ART (efavirenz [EFV]/tenofovir disoproxil fumarate + emtricitabine (FTC) or lamivudine (3TC). We studied adults (≥fifteen years) with CD4 ≥ 350/μL and children (two to fourteen years) with CD4 > 500/μL otherwise ineligible for ART by country guidelines. Clinics implemented a patient-centred streamlined care model designed to reduce patient-level barriers and maximize health system efficiency. It included (1) nurse-conducted visits with physician referral of complex cases, (2) multi-disease chronic care (including for hypertension/diabetes), (3) patient-centred, friendly staff, (4) viral load (VL) testing and counselling, (5) three-month return visits and ART refills, (6) appointment reminders, (7) tiered tracking for missed appointments, (8) flexible clinic hours (outside routine schedule) and (9) telephone access to clinicians. Primary outcomes were 48-week retention in care, viral suppression (% with measured week 48 VL ≤ 500 copies/mL) and adverse events. Results Overall, 972 HIV-positive adults with CD4+ ≥ 350/μL initiated ART with streamlined care. Patients were 66% female and had median age thirty-four years (IQR, 28-42), CD4+ 608/μL (IQR, 487-788/μL) and VL 6775 copies/mL (IQR, <500-37,003 c/mL). At week 48, retention was 92% (897/972; 2 died/40 moved/8 withdrew/4 transferred care/21/964 [2%] were lost to follow-up). Viral suppression occurred in 778/838 (93%) and 800/972 (82%) in intention-to-treat analysis. Grade III/IV clinical/laboratory adverse events were rare: 95 occurred in 74/972 patients (7.6%). Only 8/972 adults (0.8%) switched ART from EFV to lopinavir (LPV) (n = 2 for dizziness, n = 2 for gynaecomastia, n = 4 for other reasons). Among 83 children, week 48 retention was 89% (74/83), viral suppression was 92% (65/71) and grade III/IV adverse events occurred in 4/83 (4.8%). CONCLUSIONS: Using a streamlined care model, viral suppression, retention and ART safety were high among asymptomatic East African adults and children with high CD4+ counts initiating treatment. CLINICAL TRIAL NUMBER: NCT01864603

Integrating various energy saving initiatives on compressed air systems of typical South African gold mines

Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012.Electrical energy is commonly used in households and in industry - demand continues to rise due to economic and population growth. This requires that energy suppliers must increase their supply capacity. The result is that end–user energy costs continue to increase, therefore a growing need exists to reduce electrical energy demand in South Africa and internationally. Households account for the majority of electrical energy customers, but they only consume a fraction of the total energy supplied. The industrial sector and mines combined consume approximately 42% of the total electrical energy produced. Approximately 10% of this energy goes into compressed air production. This study focuses on methods of reducing the requirement of compressed air in industry so that the demand for electrical energy can be reduced. Many studies have focused on specific methods of reducing energy usage associated with compressed air production. These methods are categorised into methods of reducing compressed air requirements and methods of increasing compressed air supply efficiency. This study aims to combine these efforts into a single optimised solution. Although this study includes industry in general, the central focus is on the South African mining industry. Two different mining sites are considered and analysed as case studies. Methods of reducing energy required to produce compressed air were applied to each case study. Case Study 1 only allowed limited control of the compressed air system. In Case Study 2 integrated control was realised. Energy usage of compressors was reduced by 18.9% and 42.9% respectively. Results show that system savings can be doubled by combining different methods of reducing energy usage of compressed air. This, however, requires continuous monitoring and control of the air network at each section supplied with compressed air. The study is limited to achieving savings by changing the air system. Additional savings can be achieved by training personnel, altering schedules of production activities and implementing a system designed to locate air leaks.Master

Sex determination of Kelp Gull Larus dominicanus vetula using head and bill measurements

Kelp Gulls Larus dominicanus are not sexually dimorphic by plumage or visual characteristics and it is therefore difficult to distinguish males from females in the field. This paper assesses the sexual size dimorphism in this species and provides reliable methods for predicting sex of measured individuals. Discriminant function analysis of three commonly measured morphometric characters of adult birds indicated that the combination of head length and bill depth were the most accurate variables to use in a discriminant function model, predicting the sex with 97% accuracy. French title: Détermination du sexe du Goéland du Cap Larus dominicanus vetula par mesure de la tête et du bec Les Goélands du Cap Larus dominicanus ne sont pas sexuellement dimorphiques par leur plumage ou par des caractéristiques&nbsp; visuelles, ce qui complique l’identification des mâles et des femelles sur le terrain. Cet article évalue le dimorphisme sexuel portant sur la taille de de cette espèce et fournit des méthodes fiables pour prédire le sexe des individus mesurés. L’analyse discriminante&nbsp; prédictive de trois caractères morphologiques couramment mesurés chez des oiseaux adultes a conclu que la combinaison de la longueur de la tête et de la hauteur du bec sont les variables les plus précises à utiliser dans un modèle de fonction discriminante, prédisant le sexe avec une précision de 97%. Keywords: discriminant function analysis, measurements, sexing method, South Afric