172 research outputs found
Developing a legal framework for e-commerce in South Africa
Modern-day consumers procure goods and services using electronic transaction method (ecommerce). E-commerce is growing at a rapid pace throughout the world including South Africa. The whole transaction involves the exchange of commodities and information or data transfer between consumers and businesses. It is a convenient and faster method in comparison to the traditional physical transaction. An extension to e-commerce is the development of Mobilecommerce otherwise known as M-commerce, which entails the use of a mobile phone for everyday transactions. Mobile technology and the use of mobile devices have made the mobile commerce market more orientated due to its easy access. It is evident that e-commerce and M-commerce play an integral part of how business is done domestically and internationally. The use of these technologies comes with number of challenges such as the inaccuracy of information of the goods advertised on the internet, delivered goods inconsistent with consumer’s specifications, inability to physically examine the goods before making payment, information of the supplier, loss of data or information are some of the challenges. To address those challenges the Electronic Communications and Transactions Act 25 of 2002 (ECT) was enacted to deal exclusively with issues relating to electronic transactions. The Consumer Protection Act, 68 of 2008 also provides extensive protection to the consumers. This dissertation examines the provision of existing legislation dealing with online consumer protection considering that internet transactions are borderless. It also investigates how effectiveness as well the comparison of Online dispute resolution mechanism in South African with international standards.Mini Dissertation (LLM)--University of Pretoria, 2019.National Research Foundation.Centre for Human RightsLLMUnrestricte
Performance analysis of biological resource allocation algorithms for next generation networks.
Masters Degree. University of KwaZulu-Natal, Durban.Abstract available in PDF.Publications listed on page iii
A Cosmic Ray Positron Anisotropy due to Two Middle-Aged, Nearby Pulsars?
Geminga and B0656+14 are the closest pulsars with characteristic ages in the
ran ge of 100 kyr to 1 Myr. They both have spindown powers of the order 3e34
erg/s at present. The winds of these pulsars had most probably powered pulsar
wind nebulae (PWNe) that broke up less than about 100 kyr after the birth of
the pulsars. Assuming that leptonic particles accelerated by the pulsars were
confined in th e PWNe and were released into the interstellar medium (ISM) on
breakup of the PW Ne, we show that, depending on the pulsar parameters, both
pulsars make a non-ne gligible contribution to the local cosmic ray (CR)
positron spectrum, and they m ay be the main contributors above several GeV.
The relatively small angular dist ance between Geminga and B0656+14 thus
implies an anisotropy in the local CR po sitron flux at these energies. We
calculate the contribution of these pulsars to the locally observed CR electr
on and positron spectra depending on the pulsar birth period and the magnitude
o f the local CR diffusion coefficient. We further give an estimate of the
expecte d anisotropy in the local CR positron flux. Our calculations show that
within the framework of our model, the local CR posit ron spectrum imposes
constraints on pulsar parameters for Geminga and B0656+14, notably the pulsar
period at birth, and also the local interstellar diffusion co efficient for CR
leptons.Comment: accepted for publication in ApJ
Suppressed phase variations in a high amplitude rapidly oscillating Ap star pulsating in a distorted quadrupole mode
We present the results of a multisite photometric observing campaign on the rapidly oscillating Ap (roAp) star 2MASS 16400299-0737293 (J1640; ). We analyse photometric data to show the star pulsates at a frequency of d (Hz; min) with a peak-to-peak amplitude of 20.68 mmag, making it one of the highest amplitude roAp stars. No further pulsation modes are detected. The stellar rotation period is measured at d, and we show that rotational modulation due to spots is in anti-phase between broadband and observations. Analysis and modelling of the pulsation reveals this star to be pulsating in a distorted quadrupole mode, but with a strong spherically symmetric component. The pulsational phase variation in this star is suppressed, leading to the conclusion that the contribution of components dictate the shape of phase variations in roAp stars that pulsate in quadrupole modes. This is only the fourth time such a strong pulsation phase suppression has been observed, leading us to question the mechanisms at work in these stars. We classify J1640 as an A7 Vp SrEu(Cr) star through analysis of classification resolution spectra
Spatially resolved XMM-Newton analysis and a model of the nonthermal emission of MSH 15-52
We present an X-ray analysis and a model of the nonthermal emission of the
pulsar wind nebula (PWN) MSH15-52. We analyzed XMM-Newton data to obtain the
spatially resolved spectral parameters around the pulsar PSRB1509-58. A
steepening of the fitted power-law spectra and decrease in the surface
brightness is observed with increasing distance from the pulsar. In the second
part of this paper, we introduce a model for the nonthermal emission, based on
assuming the ideal magnetohydrodynamic limit. This model is used to constrain
the parameters of the termination shock and the bulk velocity of the leptons in
the PWN. Our model is able to reproduce the spatial variation of the X-ray
spectra. The parameter ranges that we found agree well with the parameter
estimates found by other authors with different approaches. In the last part of
this paper, we calculate the inverse Compton emission from our model and
compare it to the emission detected with the H.E.S.S. telescope system. Our
model is able to reproduce the flux level observed with H.E.S.S., but not the
spectral shape of the observed TeV {\gamma}-ray emission.Comment: Accepted for publication in A&A, 9 pages, 15 figure
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