Environmental enrichment, sexual dimorphism, and brain size in sticklebacks

Evidence for phenotypic plasticity in brain size and the size of different brain parts is widespread, but experimental investigations into this effect remain scarce and are usually conducted using individuals from a single population. As the costs and benefits of plasticity may differ among populations, the extent of brain plasticity may also differ from one population to another. In a common garden experiment conducted with three-spined sticklebacks (Gasterosteus aculeatus) originating from four different populations, we investigated whether environmental enrichment (aquaria provided with structural complexity) caused an increase in the brain size or size of different brain parts compared to controls (bare aquaria). We found no evidence for a positive effect of environmental enrichment on brain size or size of different brain parts in either of the sexes in any of the populations. However, in all populations, males had larger brains than females, and the degree of sexual size dimorphism (SSD) in relative brain size ranged from 5.1 to 11.6% across the populations. Evidence was also found for genetically based differences in relative brain size among populations, as well as for plasticity in the size of different brain parts, as evidenced by consistent size differences among replicate blocks that differed in their temperature.Peer reviewe

Probing microscopic origins of confined subdiffusion by first-passage observables

Subdiffusive motion of tracer particles in complex crowded environments, such as biological cells, has been shown to be widepsread. This deviation from brownian motion is usually characterized by a sublinear time dependence of the mean square displacement (MSD). However, subdiffusive behavior can stem from different microscopic scenarios, which can not be identified solely by the MSD data. In this paper we present a theoretical framework which permits to calculate analytically first-passage observables (mean first-passage times, splitting probabilities and occupation times distributions) in disordered media in any dimensions. This analysis is applied to two representative microscopic models of subdiffusion: continuous-time random walks with heavy tailed waiting times, and diffusion on fractals. Our results show that first-passage observables provide tools to unambiguously discriminate between the two possible microscopic scenarios of subdiffusion. Moreover we suggest experiments based on first-passage observables which could help in determining the origin of subdiffusion in complex media such as living cells, and discuss the implications of anomalous transport to reaction kinetics in cells.Comment: 21 pages, 3 figures. Submitted versio

Lived experience of positional suffering for room attendants at Rhodes University: insights for the transformation agenda

Taking insights from the domestic work literature both locally and internationally, this study explores the lived experiences of room attendants who work as cleaners in the students’ residences at Rhodes University. The study focuses on the housekeeping division of Rhodes University. Data was generated from in-depth individual interviews and focus groups with 26 women and 3 men participants (aged between 28 and 60) who work as room attendants, and who were recruited from the residences across the university. The phenomenological approach allowed the participants to articulate in-depth, their experiences of working as room attendants in intimate spaces. This study used a triangulated conceptual framework, which amalgamated the concepts of pain, social space and intersectionality, and exploitation under the umbrella concept of positional suffering. Within a higher education transformation agenda which has marginalised the experiences of unskilled workers at the university, the study seeks to bring insights to the understanding of transformation at Rhodes University through the experiences of the being-in-the-world of room attendants

A study on the tolerance of intermittent hypoxia training and its effect on sensory and motor spinal pathways

Intermittent hypoxia is defined as brief exposures of low oxygen concentration. It is commonly associated with a disease state known as obstructive sleep apnoea, however, a mild to moderate form can benefit patients with spinal cord injury. Studies have shown that a single exposure of intermittent hypoxia enhances the excitability of spinal connections spared following a cord injury. The enhanced excitability may last for more than an hour and during this time medical professionals can use conventional rehabilitation therapies and offer a heighten rehabilitation outcome and perhaps even speed up recovery. Nevertheless, there is a limited understanding in the tolerance of the intermittent hypoxia protocol given to spinal cord injury patients and its effects on spinal pathways. The purpose of this thesis was to go back to the basics and study intermittent hypoxia on healthy volunteers. To examine the tolerance, and to also find an appropriate IHT intervention that challenged the homeostasis of healthy volunteers, measurements of heart rate, saturation of oxygen in the blood, and blood pressure were taken. To analyse the response of the autonomic nervous system, heart rate variability was analysed. Regarding the investigation on spinal pathways, the effect on the sensory and motor pathways was examined by recording somatosensory evoked potentials and motor evoked potentials. These measurements were taken prior, during and up to 30 minutes following the IHT intervention. Results showed that a single exposure of IHT given to healthy young volunteers was well tolerated and its effects were long lasting and localised on the corticospinal tract following a stimulus on the motor cortex. Yet, to know the true potential of its ability to alter corticospinal excitability it is also essential to study its effect on skeletal muscle metabolism and as a result on force.Intermittent hypoxia is defined as brief exposures of low oxygen concentration. It is commonly associated with a disease state known as obstructive sleep apnoea, however, a mild to moderate form can benefit patients with spinal cord injury. Studies have shown that a single exposure of intermittent hypoxia enhances the excitability of spinal connections spared following a cord injury. The enhanced excitability may last for more than an hour and during this time medical professionals can use conventional rehabilitation therapies and offer a heighten rehabilitation outcome and perhaps even speed up recovery. Nevertheless, there is a limited understanding in the tolerance of the intermittent hypoxia protocol given to spinal cord injury patients and its effects on spinal pathways. The purpose of this thesis was to go back to the basics and study intermittent hypoxia on healthy volunteers. To examine the tolerance, and to also find an appropriate IHT intervention that challenged the homeostasis of healthy volunteers, measurements of heart rate, saturation of oxygen in the blood, and blood pressure were taken. To analyse the response of the autonomic nervous system, heart rate variability was analysed. Regarding the investigation on spinal pathways, the effect on the sensory and motor pathways was examined by recording somatosensory evoked potentials and motor evoked potentials. These measurements were taken prior, during and up to 30 minutes following the IHT intervention. Results showed that a single exposure of IHT given to healthy young volunteers was well tolerated and its effects were long lasting and localised on the corticospinal tract following a stimulus on the motor cortex. Yet, to know the true potential of its ability to alter corticospinal excitability it is also essential to study its effect on skeletal muscle metabolism and as a result on force

Assessment of the challenges affecting the efficient and effective management of district hospitals in the Motheo district in the Free State province

Thesis (M. Tech. (Public Management)) -- Central University of Technology, free State, [2014]The primary aim of the proposed study is to investigate the technical problems affecting the efficiency and effectiveness of District Hospitals in the Free State Province. The proposed research therefore stands to contribute to the existing body of evidence on the efficiency and effectiveness of health care services, with regard to the existing problems in the health sector such as high staff turnover, facilities with lack of appropriate equipment, unmanageable workload, lack of appropriate infrastructure, a high absenteeism rate and low morale of the employees in the public health institutions. Therefore the study will identify potential shortcomings that are compromising the efficiency and effectiveness of the district hospitals. The findings of the study will be used to address some of the identified problems and also to describe how progress can be measured. The outcomes of this study are intended to raise important issues and to assist management of the Free State Department of Health to address the challenges that are affecting the functioning of the district hospitals. The findings will also assist the relevant managers in planning and implementation of policies that will address inequalities and problems as highlighted in the study. It will also create opportunities for shared responsibilities that management and the staff need to resolve jointly

Single particle tracking in systems showing anomalous diffusion: the role of weak ergodicity breaking

Anomalous diffusion has been widely observed by single particle tracking microscopy in complex systems such as biological cells. The resulting time series are usually evaluated in terms of time averages. Often anomalous diffusion is connected with non-ergodic behaviour. In such cases the time averages remain random variables and hence irreproducible. Here we present a detailed analysis of the time averaged mean squared displacement for systems governed by anomalous diffusion, considering both unconfined and restricted (corralled) motion. We discuss the behaviour of the time averaged mean squared displacement for two prominent stochastic processes, namely, continuous time random walks and fractional Brownian motion. We also study the distribution of the time averaged mean squared displacement around its ensemble mean, and show that this distribution preserves typical process characteristic even for short time series. Recently, velocity correlation functions were suggested to distinguish between these processes. We here present analytucal expressions for the velocity correlation functions. Knowledge of the results presented here are expected to be relevant for the correct interpretation of single particle trajectory data in complex systems.Comment: 15 pages, 15 figures; References adde