Browsing Faculty of Natural Sciences by Title
Now showing items 9-28 of 551
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Acylphloroglucinol derivatives from the South African helichrysum niveum and their biological activities
(MDPI, 2015)Abstract: Phytochemical investigation of aerial parts of Helichrysum niveum (H. niveum) using different chromatographic methods including semi-preparative HPLC afforded three new (1–3) and six known (4–10) acylphloroglucinols ... -
Adapting x264 to asynchronous video telephony for the Deaf
(Telkom, 2008)Deaf people want to communicate remotely with sign language. Sign language requires sufficient video quality to be intelligible. Internet-based real-time video tools do not provide that quality. Our approach is to use ... -
Additive antibacterial activity of naringenin and antibiotic combinations against multidrug resistant Staphylococcus aureus
(Academic Journals, 2015)Methicillin-resistant Staphylococcus aureus has been causing numerous problems in the health care sector. This is mainly due to its ability to develop resistance to a number of antibiotics used to treat staphylococcal ... -
Affective gesture feedback Instant Messaging on handhelds
(Institute of Electrical and Electronics Engineers, Inc., 2004)Mobile devices and mobile networks are becoming more data-centric (evident in Japanese I-mode) even as mobile network voice Average Revenue Per User are declining, new stream of data services are required which must take ... -
The African Coelecanth genome provides insights into tetrapod evolution
(Macmillan Publishers, 2013)The discovery of a living coelacanth specimen in 1938 was remarkable, as this lineage of lobe-finned fish was thought to have become extinct 70 million years ago. The modern coelacanth looks remarkably similar to many of ... -
Agent-based context-aware healthcare information retrieval using DROPT approach
(International Science Press, 2012)As the volume of information available on the Web information systems is growing continuously, browsing this content becomes a tedious task given the presentation of data that does meet user's aims and needs. In this paper, ... -
Alteration of Bax-to-Bcl-2 ratio modulates the anticancer activity of methanolic extract of Commelina benghalensis (Commelinaceae) in Jurkat T cells
(Academic Journals, 2008)Stem extracts of Commelina benghalensis (Linn.), although not extensively documented, are frequently used in traditional medicine for the treatment of ailments such as skin malformations and outgrowths. Accordingly, the ... -
Amino acids 1055 to 1192 in the S2 Region of severe acute respiratory syndrome Coronavirus S Protein induce neutralizing antibodies: Implications for the development of vaccines and antiviral agents
(American Society for Microbiology, 2005)The spike (S) protein of the severe acute respiratory syndrome coronavirus (SARS-CoV) interacts with cellular receptors to mediate membrane fusion, allowing viral entry into host cells; hence it is recognized as the primary ... -
Amorphous Pt@dCu/CNT catalyst for methanol elextrooxidation
(South African Chemical Institute (SACI), 2013)A multi-walled carbon nanotube-supported, Pt decorated nano-sized amorphous PdCu alloy cores (denoted as Pt@PdCu/CNT) catalyst with lower Pt loading is synthesized via a galvanic displacement reaction. The structure is ... -
Amphibious Horses: Beings in the Littoral and Liminal Contact Zones
(2013)Horses galloping in littoral zones are represented as embodying wildness, freedom and a prelapsarian quality. Roy Campbell’s ‘The Horses of the Camargue’ includes themes which recur in texts about littoral horses: the ... -
An unconditionally stable nonstandard finite difference method applied to a mathematical model of HIV infection
(De Gruyter Open, 2013)We formulate and analyze an unconditionally stable nonstandard finite difference method for a mathematical model of HIV transmission dynamics. The dynamics of this model are studied using the qualitative theory of dynamical ... -
Anaerobes and bacterial vaginosis in pregnancy: virulence factors contributing to vaginal colonisation
(Multidisciplinary Digital Publishing Institute, 2014)The aetiology and pathogenesis of bacterial vaginosis (BV) is unclear but it appears to be associated with factors that disrupt the normal acidity of the vagina thus altering the equilibrium between the normal vaginal ... -
The analysis of indexed astronomical time series – X. Significance testing of O − C data
(Oxford University Press, 2006)It is assumed that O − C (‘observed minus calculated’) values of periodic variable stars are determined by three processes, namely measurement errors, random cycle-to-cycle jitter in the period, and possibly long-term ... -
The analysis of indexed astronomical time series – XI. The statistics of oversampled white noise periodograms
(Oxford University Press, 2015)The distribution of the maxima of periodograms is considered in the case where the time series is made up of regularly sampled, uncorrelated Gaussians. It is pointed out that if there is no oversampling, then for large ... -
The analysis of indexed astronomical time series – XII. The statistics of oversampled Fourier spectra of noise plus a single sinusoid
(Oxford University Press, 2015)With few exceptions, theoretical studies of periodogram properties focus on pure noise time series. This paper considers the case in which the time series consists of noise together with a single sinusoid, observed at ... -
The analysis of irregularly observed stochastic astronomical time-series – I. Basics of linear stochastic differential equations
(Oxford University Press, 2005)The theory of low-order linear stochastic differential equations is reviewed. Solutions to these equations give the continuous time analogues of discrete time autoregressive time-series. Explicit forms for the power ... -
An analysis of pulsation periods of long period
(Royal Statistical Society, 2007)Summary: We report the results of a period change analysis of time series observations for 378 pulsating variable stars. The null hypothesis of no trend in expected periods is tested for each of the stars. The tests are ... -
An analysis of voice over Internet Protocol in wireless mesh networks
(IEEE, 2014)The paper focuses on analyzing the affects of wireless mesh networks with some mobile nodes on Voice over Internet Protocol service quality. Our interest is to examine this in simulation to learn how to better deploy voice ... -
ANCAEE: A novel clustering algorithm for energy efficiency in wireless sensor networks
(Scientific Research Publishing, 2011)One of the major constraints of wireless sensor networks is limited energy available to sensor nodes because of the small size of the batteries they use as source of power. Clustering is one of the routing techniques that ... -
Antarctic Dry Valley mineral soils contain unexpectedly high levels of microbial biomass
(Springer Verlag, 2002)We have applied bioluminescent ATP detection methods to microbial enumeration in Antarctic Dry Valley mineral soils, and validated our ATP data by two independent methods. We have demonstrated that ATP measurement is ...
