List of Titles

First evidence for the Cenomanian-Turonian oceanic anoxic event (OAE2, Bonarelli event) from the Ionian Zone, western continental Greece

- Karakitsios, V, Tsikos, Harilaos, Van Breugel, Y, Koletti, L, Sinninghe Damsté, J S, Jenkyns, H C

Authors: Karakitsios, V , Tsikos, Harilaos , Van Breugel, Y , Koletti, L , Sinninghe Damsté, J S , Jenkyns, H C
Date: 2007
Language: English
Type: Article
Identifier: vital:6735 , http://hdl.handle.net/10962/d1007547
Description: Integrated biostratigraphic (planktonic foraminifera, calcareous nannofossils), chemostratigraphic (bulk C and O isotopes) and compound-specific organic geochemical studies of a mid-Cretaceous pelagic carbonate—black shale succession of the Ionian Zone (western Greece), provide the first evidence for the Cenomanian–Turonian oceanic anoxic event (OAE2, ‘Bonarelli’ event) in mainland Greece. The event is manifested by the occurrence of a relatively thin (35 cm), yet exceptionally organic carbon-rich (44.5 wt% TOC), carbonate-free black shale, near the Cenomanian–Turonian boundary within the Vigla limestone formation (Berriasian–Turonian). Compared to the ‘Bonarelli’ black-shale interval from the type locality of OAE2 in Marche–Umbria, Italy, this black shale exhibits greatly reduced stratigraphic thickness, coupled with a considerable relative enrichment in TOC. Isotopically, enriched δ[superscript 13]C values for both bulk organic matter (−22.2‰) and specific organic compounds are up to 5‰ higher than those of underlying organic-rich strata of the Aptian-lower Albian Vigla Shale member, and thus compare very well with similar values of Cenomanian–Turonian black shale occurrences elsewhere. The relative predominance of bacterial hopanoids in the saturated, apolar lipid fraction of the OAE2 black shale of the Ionian Zone supports recent findings suggesting the abundance of N[subscript 2]-fixing cyanobacteria in Cretaceous oceans during the Cenomanian–Turonian and early Aptian oceanic anoxic events.
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Date Issued: 2007

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M 87 at metre wavelengths: the LOFAR picture

- Smirnov, Oleg M, De Gasperin, F, Orrú, E, Murgia, M, Merloni, A, Falcke, H, Beck, R, Beswick, R, Bîrzan, L, Bonafede, A, Brüggen, M

Authors: Smirnov, Oleg M , De Gasperin, F , Orrú, E , Murgia, M , Merloni, A , Falcke, H , Beck, R , Beswick, R , Bîrzan, L , Bonafede, A , Brüggen, M
Date: 2012
Subjects: radiation mechanisms: non-thermal, galaxies: active, galaxies: individual: M 87, galaxies: clusters: individual: Virgo, galaxies: jets, radio continuum: galaxies
Language: English
Type: Article
Identifier: vital:6821 , http://hdl.handle.net/10962/d1004434
Description: Context.M 87 is a giant elliptical galaxy located in the centre of the Virgo cluster, which harbours a supermassive black hole of mass 6.4 × 109 M⊙, whose activity is responsible for the extended (80 kpc) radio lobes that surround the galaxy. The energy generated by matter falling onto the central black hole is ejected and transferred to the intra-cluster medium via a relativistic jet and morphologically complex systems of buoyant bubbles, which rise towards the edges of the extended halo. Aims. To place constraints on past activity cycles of the active nucleus, images of M 87 were produced at low radio frequencies never explored before at these high spatial resolution and dynamic range. To disentangle different synchrotron models and place constraints on source magnetic field, age and energetics, we also performed a detailed spectral analysis of M 87 extended radio-halo. Methods. We present the first observations made with the new Low-Frequency Array (LOFAR) of M 87 at frequencies down to 20 MHz. Three observations were conducted, at 15−30 MHz, 30−77 MHz and 116−162 MHz. We used these observations together with archival data to produce a low-frequency spectral index map and to perform a spectral analysis in the wide frequency range 30 MHz–10 GHz. Results. We do not find any sign of new extended emissions; on the contrary the source appears well confined by the high pressure of the intra-cluster medium. A continuous injection of relativistic electrons is the model that best fits our data, and provides a scenario in which the lobes are still supplied by fresh relativistic particles from the active galactic nuclei. We suggest that the discrepancy between the low-frequency radio-spectral slope in the core and in the halo implies a strong adiabatic expansion of the plasma as soon as it leaves the core area. The extended halo has an equipartition magnetic field strength of ≃10 μG, which increases to ≃13 μG in the zones where the particle flows are more active. The continuous injection model for synchrotron ageing provides an age for the halo of ≃40 Myr, which in turn provides a jet kinetic power of 6−10 × 1044 erg s-1.
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Date Issued: 2012

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The human skin blanching assay for in vivo topical corticosteroid assessment. II. Subject- and observer-dependent variation in blanching responses

- Haigh, John M, Meyer, Eric, Smith, Eric W, Kanfer, Isadore

Authors: Haigh, John M , Meyer, Eric , Smith, Eric W , Kanfer, Isadore
Date: 1997
Language: English
Type: text , Article
Identifier: vital:6382 , http://hdl.handle.net/10962/d1006300
Description: The human skin blanching (vasoconstriction) assay for the assessment of topical corticosteroids has been in use for over 30 years, the intensity of the drug-induced blanching being assessed subjectively by eye. Both arms of several male and female volunteers are used for product application and more than one observer is used to estimate the degree of induced blanching. There are, therefore, numerous variables which are inherent in the assay procedure. This investigation consisted of three identical trials performed at 8-week intervals, utilising the same 18 volunteers and the same three observers in an attempt to address the question of reproducibility of the assay. From the results obtained it is clear that the assay methodology is capable of consistently distinguishing, on a rank order basis, between preparations which show similar blanching (chemically-equivalent formulations). The similarity of the results for the three individual trials gives considerable confidence to results produced using this methodology. An experiment designed to test the reproducibility of the blanching scores showed that the observers are capable of producing identical results even though visual observation is highly subjective.
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Date Issued: 1997

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In vitro release of propranolol hydrochloride from topical vehicles

- Smith, Eric W, Haigh, John M

Authors: Smith, Eric W , Haigh, John M
Date: 1994
Language: English
Type: text , Article
Identifier: vital:6435 , http://hdl.handle.net/10962/d1006612
Description: Transdermal drug delivery is becoming increasingly important and for this reason it is clear that academia must ensure that current graduates are knowledgeable in all facets of topical drug administration. An in vitro diffusion cell experiment was designed to demonstrate the rate of release of propranolol hydrochloride (PHC) from three different topical vehicles: (i) an oil-in-water cream; (ii) a gel; and (iii) anointment. This experiment was performed by final-year students enroled in an undergraduate course on percutaneous absorption. In vitro release of PHC from the three bases to an aqueous receptor phase through silicone membrane was monitored spectrophotometrically at a wavelength of 290 nm. By monitoring and attempting to explain the numerous possible reasons for the different rates of drug release from the three vehicles, it was hoped that the students would gain a better understanding of the complexities of transdermal drug administration. Overall, the experiment would appear to be a good model for student investigation into factors affecting the release of drugs from topical formulations.
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Date Issued: 1994

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The transportability and utility of cognitive therapy in South African contexts: a review

- Young, Charles

Authors: Young, Charles
Date: 2009
Language: English
Type: Article
Identifier: vital:6279 , http://hdl.handle.net/10962/d1008280
Description: Cognitive therapy could be more widely promoted in South Africa given the great disparity between the need and provision of psychological therapies. Three possible objections to the promotion of cognitive therapy are considered: uncertainty surrounding the effectiveness of cognitive therapy in South African contexts; uncertainty surrounding the applicability in multicultural contexts; and suggestions that cognitive therapy is decontextualised and therefore objectionable in a country facing major social challenges. A systematic review of the literature indentified 15 outcome studies, and suggests that cognitive therapy is a viable and much-needed approach in South Africa.
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Date Issued: 2009

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Electrocatalysis of oxidation of 2-mercaptoethanol, L-cysteine and reduced glutathione by adsorbed and electrodeposited cobalt tetra phenoxypyrrole and tetra ethoxythiophene substituted phthalocyanines

- Sehlotho, Nthapo, Nyokong, Tebello, Zagal, Jose H, Bedioui, Fethi

Authors: Sehlotho, Nthapo , Nyokong, Tebello , Zagal, Jose H , Bedioui, Fethi
Date: 2006
Language: English
Type: Article
Identifier: vital:6593 , http://hdl.handle.net/10962/d1004342
Description: Catalytic activity of cobalt tetra ethoxythiophene and cobalt tetra phenoxypyrrole phthalocyanine complexes towards oxidation of 2-mercaptoethanol, L-cysteine and reduced glutathione is reported. It was found that the activity of the complexes depends on the substitution of the phthalocyanine ring, pH, film thickness and method of electrode modification. The high electrocatalytic activity obtained with adsorbed complexes in alkaline medium clearly demonstrates the necessity of modifying bare carbon electrodes to endow them with the desired behaviour.
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Date Issued: 2006

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A history of southern African research relevant to forensic entomology

- Williams, K A, Villet, Martin H

Authors: Williams, K A , Villet, Martin H
Date: 2006
Language: English
Type: text , Article
Identifier: vital:6909 , http://hdl.handle.net/10962/d1011862
Description: Entomological forensic evidence has been used in southern Africa for decades but explicitly forensic research began in southern Africa only 26 years ago. Although applicable local research has accumulated since 1921, it is scattered in a diverse literature or unpublished. Some overseas research has also touched on local species. This review uses a historical approach to synthesize the southern African literature and to illustrate the cross-disciplinary, opportunistic nature of forensic entomology. Distinct phases of research focused on agriculture (1921-1950), medicine (1952- 1965), ecology (1968-1990) and forensics (1980-2005), but systematics spanned the entire period and tended to be ad hoc. Few scientists were involved, situated at geographically distant locations and with widely disparate research interests. The review concludes with an overview of southern African entomologists who have been involved in medico-legal investigations, and a critical evaluation of the past and future of the discipline locally.
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Date Issued: 2006

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