Browsing Faculty of Natural Sciences by Title
Now showing items 1644-1663 of 2571
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A NSFD discretization of two-dimensional singularly perturbed semilinear convection-diffusion problems
(Frontiers Media, 2022)Despite the availability of an abundant literature on singularly perturbed problems, interest toward non-linear problems has been limited. In particular, parameter-uniform methods for singularly perturbed semilinear ... -
A NSFD method for the singularly perturbed Burgers-Huxley equation
(Frontiers Media, 2023)This article focuses on a numerical solution of the singularly perturbed Burgers-Huxley equation. The simultaneous presence of a singular perturbation parameter and the nonlinearity raise the challenge of finding a reliable ... -
A NSFD method for the singularly perturbed Burgers-Huxley equation
(Frontiers Media, 2023)This article focuses on a numerical solution of the singularly perturbed Burgers-Huxley equation. The simultaneous presence of a singular perturbation parameter and the nonlinearity raise the challenge of finding a ... -
Null models for null hypotheses in taxonomy: A test using Scyphozoa
(Oxford University Press, 2021)Although molecular tools are becoming more important in the delineation of scyphozoan species there is, perforce, a need to substantiate new species definitions using morphological data. Access to type material is often ... -
A null test to probe the scale dependence of the growth of structure as a test of general relativity
(Oxford University Press, 2019)The main science driver for the coming generation of cosmological surveys is understanding dark energy that relies on testing general relativity on the largest scales. Once we move beyond the simplest explanation for dark ... -
Null tests of the concordance model in the era of Euclid and the SKA
(Elsevier, 2021)We perform null tests of the concordance model, using H (z) measurements that mimic next-generation surveys such as Euclid and the SKA. To this end, we deploy a non-parametric method, so that we make minimal assumptions ... -
Null tests of the cosmological constant using supernovae
(American Physical Society, 2014)The standard concordance model of the Universe is based on the cosmological constant as the driver of accelerating expansion. This concordance model is being subjected to a growing range of inter-locking observations. ... -
Numerical solution for a problem arising in angiogenic signalling
(American Institute of Mathematical Sciences, 2019)Since the process of angiogenesis is controlled by chemical signals, which stimulate both repair of damaged blood vessels and formation of new blood vessels, then other chemical signals known as angiogenesis inhibitors ... -
Numerical treatment of Kap's equation using a class of fourth order method
(Academic Journals, 2011)Kap's equation is a stiff initial value problem. This paper deals with the treatment of Kap's equation using a class of 4th order explicit Runge-Kutta method. Numerical computation was carried out using Microsoft Visual ... -
Nutritional quality of Calobota sericea fodders. A preliminary assessment
(Taylor and Francis, 2021)This study aimed to provide preliminary information regarding the nutritional quality of Calobota sericea, a preferred perennial legume forage species from the water-limited rangelands of South Africa. Calobota sericea ... -
The Nyquist frequency for irregularly spaced time-series: a calculation formula
(Oxford University Press, 2006)Eyer & Bartholdi showed that the Nyquist frequency of irregularly sampled time-series can be very high. In this paper, a calculation formula for the Nyquist frequency is presented. In practice there is an upper limit of ... -
The Nyquist frequency for time series with slight deviations from regular spacing
(Oxford University Press, 2009)The paper is based on the notion that the Nyquist frequency νN is a symmetry point of the periodogram of a time series: the power spectrum at frequencies above νN is a mirror image of that below νN. Koen showed that the ... -
Obesity is associated with increased seminal insulin and leptin alongside reduced fertility parameters in a controlled male cohort
(BioMed Central, 2014)Obesity appears to be associated with male reproductive dysfunction and infertility, although this has been inconsistent and inconclusive. Insulin and leptin are known mediators and modulators of the hypothalamus-pituitary-testes ... -
Observation of the 0+ 2 and γ bands in 98Ru, and shape coexistence in the Ru isotopes
(Elsevier, 2020)Excited states in 98Ru were investigated using γ-ray spectroscopy following the β-decay of 98Rh, and via the 100Ru(p,t) reaction. Combining the results from the two experiments, two states were revised to have spin-parity ... -
The observation of vibrating pear-shapes in radon nuclei
(nature communications, 2019)There is a large body of evidence that atomic nuclei can undergo octupole distortion and assume the shape of a pear. This phenomenon is important for measurements of electric-dipole moments of atoms, which would indicate ... -
Observations on euphausiid communities of the south coast of South Africa
(NISC (Pty) Ltd and Taylor& Francis, 1995)A total of 24 species of euphausiid was collected during a survey along the South African south coast during January 1992. Communities over the Agulhas Bank were of low diversity and abundance and were dominated by Nycliphanes ... -
Observations on the ecology of Pleurobrachia pileus (Ctenophora) in the southern Benguela ecosystem
(NISC (Pty) Ltd and Taylor & Francis, 2003)The vertical distribution, abundance and size composition of a population of Pleurobrachia pileus was studied during a six-day drogue study conducted off the west coast of South Africa in February 1995. The population was ... -
Observations on the pelagic decapod Pasiphaea semispinosa in the Benguela upwelling ecosystem
(NISC and Taylor & Francis, 1994)Information on vertical and horizontal distribution patterns, abundance and morphology of the decapod Pasiphaea semispinosa in the Benguela upwelling system is presented. P. semispinosa is the dominant pelagic decapod in ... -
The observed galaxy bispectrum from single-field inflation in the squeezed limit
(IOP Publishing, 2018)Using the consistency relation in Fourier space, we derive the observed galaxy bispectrum from single- eld in ation in the squeezed limit, in which one of the three modes has a wavelength much longer than the other two. ... -
Observing relativistic features in large-scale structure surveys - I. Multipoles of the power spectrum
(Oxford University Press, 2021)Planned efforts to probe the largest observable distance scales in future cosmological surveys are motivated by a desire to detect relic correlations left over from inflation and the possibility of constraining novel ...