Browsing Faculty of Natural and Agricultural Sciences by Title
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Periodic methanol masers in G9.62+0.20E (Research note)
(EDP Sciences, 2016)A number of mechanisms for understanding the periodic class II methanol masers associated with some high-mass star forming regions have been proposed in the past. Two recent proposals by Parfenov & Sobolev (2014, MNRAS, ... -
Periodic methanol masers: from a colliding wind binary (CWB) perspective
(Oxford Univ Press, 2019)Since the discovery of periodic class II methanol masers at 6.7 and 12.2 GHz associated with high-mass star formation regions (HMSFRs), a number of possible driving mechanisms have been proposed to explain this phenomenon. ... -
Periodic variability of the mainline hydroxyl masers in G9.62+0.20E
(Oxford Univ Press, 2019)We present the results of a monitoring campaign using the KAT-7 and HartRAO 26 m telescopes, of hydroxyl, methanol, and water vapour masers associated with the high-mass star-forming region G9.62+0.20E. Periodic flaring ... -
Periodicity in Class II methanol masers in high-mass star-forming regions
(Oxford Univ Press, 2014)We report the results of 10 years of monitoring of six regularly varying 6.7 GHz methanol masers using the Hartebeesthoek 26-m telescope. Observations were done at intervals of 1–2 weeks, with faster sampling during ... -
Periodicity in recurrent fast radio bursts and the origin of ultralong period magnetars
(Oxford Univ Press, 2020)The recurrent fast radio burst FRB 180916 was recently shown to exhibit a 16-d period (with possible aliasing) in its bursting activity. Given magnetars as widely considered FRB sources, this period has been attributed to ... -
Permeation enhancement effects of leaf materials from different aloe species on in vitro and ex vivo nasal epithelial models
(2020)Introduction: The nasal route of drug administration offers an alternative way for oral drug delivery and has the benefit of avoiding first-pass metabolism through drug delivery directly into the systemic circulation. The ... -
Permutation entropy analysis of magnetic field turbulence at 1AU revisited
(Wiley, 2019)Permutation entropy analysis is a relatively recent addition to the palette of techniques used to study spacecraft observations of heliospheric magnetic field fluctuations at Earth, allowing one to characterize the underlying ... -
Perovskite photodetectors based on p-i-n junction with epitaxial electron-blocking layers
(Frontiers Media, 2020)Organic-inorganic hybrid perovskite single crystals (PSCs) have been emerged as remarkable materials for some optoelectronic applications such as solid-state photodetectors, solar cells and light emitting diodes due to ... -
Perpendicular diffusion of solar energetic particles: model results and implications for electrons
(IOP Publishing, 2017)The processes responsible for the effective longitudinal transport of solar energetic particles (SEPs) are still not completely understood. We address this issue by simulating SEP electron propagation using a spatially 2D ... -
Perpendicular diffusion of solar energetic particles: when is the diffusion approximation valid?
(IOP Publishing, 2020)Multi-spacecraft observations of widespread solar energetic particle (SEP) events indicate that perpendicular (to the mean field) diffusion is an important SEP transport mechanism. However, this is in direct contrast to ... -
Persistent organic pollutants in biota samples collected during the Ymer-80 expedition to the Arctic
(Co–Action Publishing, 2015)During the 1980 expedition to the Arctic with the icebreaker Ymer, a number of vertebrate species were sampled for determination of persistent organic pollutants. Samples of Arctic char (Salvelinus alpinus, n=34), glaucous ... -
Persistent organic pollutants in the Olifants River Basin, South Africa: bioaccumulation and trophic transfer through a subtropical aquatic food web
(Elsevier, 2017)This study investigates the trophic transfer of persistent organic pollutants (POPs: PCBs, PBDEs, OCPs and PFASs) in the subtropical aquatic ecosystem of the Olifants River Basin (South Africa) by means of trophic magnification ... -
Persistent precarity and the disaster of everyday life: homeless people’s experiences of natural and other hazards
(Springer, 2019)Knowledge of how homeless people deal with natural hazards and disasters is sparse and there is a remarkable absence of homeless people in policies and practices for disaster risk reduction (DRR). This article aims at ... -
Persistent storage and query of e-government ontologies in relational databases
(Springer, 2014)Over the past eight years, building ontologies for semantic-driven e-government applications has been a subject of interest to e-government researchers. However, only a few has focused on the persistent storage and query ... -
A perspective on South African coal fired power station emissions
(Energy Research Centre, University of Cape Town, 2015)This paper investigates trends of historical and projected future South African coal-fired power station criteria (total primary Particulate Matter (PM), Sulphur Dioxide (SO2) and Nitrogen Oxides (NOx)) and Carbon ... -
Pervasive and weakly pervasive pre-Riesz spaces
(Elsevier, 2019)Pervasive pre-Riesz spaces are defined by means of vector lattice covers. To avoid the computation of a vector lattice cover, we give two distinct intrinsic characterizations of pervasive pre-Riesz spaces. We introduce ... -
Pest resistance to Cry1Ab Bt maize: field resistance, contributing factors and lessons from South Africa
(ELSEVIER, 2013)This paper documents the historical development of resistance of the African maize stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae) to Bt maize (Zea mays L.). This pest was one of the first to evolve resistance ... -
Phaeoptilum spinosum
(South African National Biodiversity Institute, 2015) -
Phase-resolved velocity flow fields induced by laboratory-generated plunging water waves
(Elsevier, 2017)Digital images of regular plunging water waves were captured by a camera and analyzed to examine the spatial and temporal evolution of phase-resolved instantaneous and ensemble-averaged velocity fields induced by the waves ...