The impact and control of alien aquatic vegetation in South African aquatic ecosystems

2003 ◽  
Vol 28 (1) ◽  
pp. 19-24 ◽  
Author(s):  
M P Hill
Keyword(s):  
South African ◽  
Aquatic Ecosystems ◽  
Aquatic Vegetation ◽  
And Control ◽  
The Impact

scholarly journals Separation of ownership and control in South African-listed companies

2013 ◽  
Vol 16 (3) ◽  
pp. 316-345 ◽  
Author(s):  
Blanché Steyn ◽  
Lesley Stainbank
Keyword(s):  
South African ◽  
Stock Exchange ◽  
Listed Companies ◽  
South African Context ◽  
Valuable Contribution ◽  
Self Interest ◽  
African Context ◽  
Using Data ◽  
And Control ◽  
The Impact

This article tests the separation of ownership and control in South African-listed companies that leads to the divergence of interest between shareholders and directors. Where listed companies are owned by so many shareholders that their diffused shareholding results in negligible control over the directors who manage the assets of the company, it is likely that the directors will manage and direct the company to maximise their self-interest to the detriment of the interest of the shareholders. The separation of ownership and control and the maximisation of self-interest are central themes in the agency theory. Researching their validity in a South African context where the market is less liquid and the stock exchange is significantly smaller can add a valuable contribution to the continuing debate on corporate governance in the country. The article analyses 186 listed South African companies using data extracted over four years to test whether there is separation of ownership and control and whether such separation leads to the maximisation of self-interest. Data were extracted for the years 2005 and 2006, using the shareholding in 2006 to determine control, and for the years 2009 and 2010, using the shareholding in 2010 to determine control. Directors’ remuneration as a percentage of assets was used as a proxy for the maximisation of directors’ interest, and profit attributable to shareholders as a percentage of assets was used as a proxy for the maximisation of shareholders’ interest. These proxies were used to test the impact of control during the two controlling periods, namely 2006 and 2010.The article finds that the majority of listed companies in South Africa are controlled by a dominant shareholder. However, there are still a significant number of companies where the directors have de facto control. Contrary to the expectation that companies controlled by directors will aim to maximise directors’ remuneration, or companies controlled by shareholders will aim to maximise profit attributable to shareholders, this article finds the opposite to be true. This is possibly an indication that the controlling parties might consider factors other than their direct financial self-interest, or that there is an inherent cost associated with control.

scholarly journals The effect of fire on soil oribatid mites (Acari: Oribatida) in a South African grassland*

Zoosymposia ◽  
2011 ◽  
Vol 6 (1) ◽  
pp. 210-220 ◽  
Author(s):  
ELIZABET A. HUGO-COETZEE ◽  
NICO L. AVENANT
Keyword(s):  
Species Richness ◽  
South African ◽  
Fire Regime ◽  
Residual Effect ◽  
Oribatid Mites ◽  
Fire Disturbance ◽  
Management Tool ◽  
Disturbance Factor ◽  
And Control ◽  
The Impact

Fire is a natural disturbance factor in southern African grasslands, and has become an important management tool for conservation of these habitats. Information on the impact of fire on any aspect of biodiversity will assist land managers to make more informed decisions on a fire regime that will conserve biodiversity in these grasslands. This is the first study to examine the responses of mite assemblages to fire disturbance in South African grasslands. The study was conducted in the Erfenis Dam Nature Reserve in central South Africa. An area of the Reserve was burned with a fast, hot fire while another area was left unburned as a control. Soil oribatid mites were collected over a period of one year from the burned and control areas. Oribatid assemblages exhibited seasonal patterns, with species richness and abundance slightly higher in early and late autumn and early spring. Four months after fire, there was no residual effect of fire on total abundance and species richness. However, species composition and the seasonal relative abundances of particular species, e.g. Multioppia wilsoni Aoki, 1964, Scheloribates confusia Coetzer, 1968 and Anellozetes auriculatus (Mahunka, 1984), differed between burned and control plots, demonstrating how targeted species can be investigated as indicators of post-fire recovery.

Suppressed, but Not Forgotten

2011 ◽  
Vol 70 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Beat Meier ◽  
Anja König ◽  
Samuel Parak ◽  
Katharina Henke
Keyword(s):  
Memory Trace ◽  
Thought Suppression ◽  
Test Phase ◽  
Indirect Test ◽  
Final Test ◽  
Test Experiment ◽  
And Control ◽  
Cue Words ◽  
The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

Research Participation Experiences of Informants of Suicide and Control Cases

Crisis ◽  
2010 ◽  
Vol 31 (5) ◽  
pp. 238-246 ◽  
Author(s):  
Paul W. C. Wong ◽  
Wincy S. C. Chan ◽  
Philip S. L. Beh ◽  
Fiona W. S. Yau ◽  
Paul S. F. Yip ◽  
...  
Keyword(s):  
Ethical Issues ◽  
Research Participation ◽  
Self Report ◽  
Initial Contact ◽  
Psychological Autopsy ◽  
Autopsy Study ◽  
The People ◽  
And Control ◽  
The Impact

Background: Ethical issues have been raised about using the psychological autopsy approach in the study of suicide. The impact on informants of control cases who participated in case-control psychological autopsy studies has not been investigated. Aims: (1) To investigate whether informants of suicide cases recruited by two approaches (coroners’ court and public mortuaries) respond differently to the initial contact by the research team. (2) To explore the reactions, reasons for participation, and comments of both the informants of suicide and control cases to psychological autopsy interviews. (3) To investigate the impact of the interviews on informants of suicide cases about a month after the interviews. Methods: A self-report questionnaire was used for the informants of both suicide and control cases. Telephone follow-up interviews were conducted with the informants of suicide cases. Results: The majority of the informants of suicide cases, regardless of the initial route of contact, as well as the control cases were positive about being approached to take part in the study. A minority of informants of suicide and control cases found the experience of talking about their family member to be more upsetting than expected. The telephone follow-up interviews showed that none of the informants of suicide cases reported being distressed by the psychological autopsy interviews. Limitations: The acceptance rate for our original psychological autopsy study was modest. Conclusions: The findings of this study are useful for future participants and researchers in measuring the potential benefits and risks of participating in similar sensitive research. Psychological autopsy interviews may be utilized as an active engagement approach to reach out to the people bereaved by suicide, especially in places where the postvention work is underdeveloped.

Using Work Domain Analysis to Evaluate the Impact of Digitization on Command and Control

2008 ◽  
Author(s):  
Daniel P. Jenkins ◽  
Neville A. Stanton ◽  
Paul M. Salmon ◽  
Guy H. Walker
Keyword(s):  
Command And Control ◽  
Domain Analysis ◽  
Work Domain Analysis ◽  
And Control ◽  
The Impact ◽  
Work Domain

Some Reflections on Reparation in Post-Apartheid South Africa, using a Couple Therapy Intervention as a Microcosm of South African Society

2011 ◽  
Vol 1 (2) ◽  
Author(s):  
Andrea Hill ◽  
Sylvia Poss
Keyword(s):  
South Africa ◽  
South African ◽  
Couple Therapy ◽  
South African Society ◽  
Depressive Position ◽  
Central Hypothesis ◽  
Transference And Countertransference ◽  
Constructive Engagement ◽  
The Impact ◽  
Therapy Intervention

The paper addresses the question of reparation in post-apartheid South Africa. The central hypothesis of the paper is that in South Africa current traumas or losses, such as the 2008 xenophobic attacks, may activate a ‘shared unconscious phantasy’ of irreparable damage inflicted by apartheid on the collective psyche of the South African nation which could block constructive engagement and healing. A brief couple therapy intervention by a white therapist with a black couple is used as a ‘microcosm’ to explore this question. The impact of an extreme current loss, when earlier losses have been sustained, is explored. Additionally, the impact of racial difference on the transference and countertransference between the therapist and the couple is explored to illustrate factors complicating the productive grieving and working through of the depressive position towards reparation.

Experimental Study of the Impact of Alisma plantago-aquatica Secretions on Pathogenic Bacteria

2014 ◽  
Vol 1 (3) ◽  
pp. 3-7
Author(s):  
O. Zhukorskyy ◽  
O. Hulay
Keyword(s):  
Pathogenic Bacteria ◽  
Initial Density ◽  
Biologically Active ◽  
Erysipelothrix Rhusiopathiae ◽  
Natural Focus ◽  
Test Species ◽  
Popula Tions ◽  
And Control ◽  
The Impact

Aim. To estimate the impact of in vivo secretions of water plantain (Alisma plantago-aquatica) on the popula- tions of pathogenic bacteria Erysipelothrix rhusiopathiae. Methods. The plants were isolated from their natural conditions, the roots were washed from the substrate residues and cultivated in laboratory conditions for 10 days to heal the damage. Then the water was changed; seven days later the selected samples were sterilized using fi lters with 0.2 μm pore diameter. The dilution of water plantain root diffusates in the experimental samples was 1:10–1:10,000. The initial density of E. rhusiopathiae bacteria populations was the same for both experimental and control samples. The estimation of the results was conducted 48 hours later. Results. When the dilution of root diffusates was 1:10, the density of erysipelothrixes in the experimental samples was 11.26 times higher than that of the control, on average, the dilution of 1:100 − 6.16 times higher, 1:1000 – 3.22 times higher, 1:10,000 – 1.81 times higher, respectively. Conclusions. The plants of A. plantago-aquatica species are capable of affecting the populations of E. rhusiopathiae pathogenic bacteria via the secretion of biologically active substances into the environment. The consequences of this interaction are positive for the abovementioned bacteria, which is demon- strated by the increase in the density of their populations in the experiment compared to the control. The intensity of the stimulating effect on the populations of E. rhusiopathiae in the root diffusates of A. plantago-aquatica is re- ciprocally dependent on the degree of their dilution. The investigated impact of water plantain on erysipelothrixes should be related to the topical type of biocenotic connections, the formation of which between the test species in the ecosystems might promote maintaining the potential of natural focus of rabies. Keywords: Alisma plantago-aquatica, in vivo secretions, Erysipelothrix rhusiopathiae, population density, topical type of connections.

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