Stellenbosch Institute for Advanced Study

South Africa

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South Africa
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News Article | April 19, 2017
Site: www.eurekalert.org

Most left-handers can rattle off a list of their eminent comrades-in-arms: Oprah Winfrey, Albert Einstein, and Barack Obama, just to name three, but they may want to add on cockatoos, "southpaw" squirrels, and some house cats. "Handed-ness" or left-right asymmetry is prevalent throughout the animal kingdom, including in pigeons and zebrafish. But why do people and animals naturally favor one side over the other, and what does it teach us about the brain's inner workings? Researchers explore these questions in a Review published April 19 in Neuron. "Studying asymmetry can provide the most basic blueprints for how the brain is organized," says lead author Onur Güntürkün, of the Institute of Cognitive Neuroscience at Ruhr-University Bochum, in Germany. "It gives us an unprecedented window into the wiring of the early, developing brain that ultimately determines the fate of the adult brain." Because asymmetry is not limited to human brains, a number of animal models have emerged that can help unravel both the genetic and epigenetic foundations for the phenomenon of lateralization. Güntürkün says that brain lateralization serves three purposes. The first of those is perceptual specialization: the more complex a task, the more it helps to have a specialized area for performing that task. For example, in most people, the right side of the brain focuses on recognizing faces, while the left side is responsible for identifying letters and words. The next area is motor specialization, which brings us to the southpaw. "What you do with your hands is a miracle of biological evolution," he says. "We are the master of our hands, and by funneling this training to one hemisphere of our brains, we can become more proficient at that kind of dexterity." Natural selection likely provided an advantage that resulted in a proportion of the population--about 10%--favoring the opposite hand. The thing that connects the two is parallel processing, which enables us to do two things that use different parts of the brain at the same time. Brain asymmetry is present in many vertebrates and invertebrates. "It is, in fact, an invention of nature, which evolved because many animals have the same needs for specialization that we do," says Güntürkün, who is also currently a visiting fellow at the Stellenbosch Institute for Advanced Study in South Africa. Studies have shown that birds, like chickens, use one eye to distinguish grain from pebbles on the ground while at the same time using the other eye to keep watch for predators overhead. Research on pigeons has shown that this specialization often is a function of environmental influences. When a pigeon chick develops in the shell, its right eye turns toward the outside, leaving its left eye to face its body. When the right eye is exposed to light coming through the shell, it triggers a series of neuronal changes that allow the two eyes to ultimately have different jobs. A zebrafish model of lateralization, meanwhile, has enabled researchers to delve into the genetic aspects of asymmetrical development. Studies of important developmental pathways, including the Nodal signaling pathway, are uncovering details about how, very early in an embryo's development, the cilia act to shuffle gene products to one side of the brain or the other. By manipulating the genes in Nodal and other pathways, researchers can study the effects of these developmental changes on zebrafish behaviors. Güntürkün says that this research can provide insight into the effects of asymmetry on brain conditions in humans. "There are almost no disorders of the human brain that are not linked to brain asymmetries," he says. "If we understand the ontogeny of lateralization, we can make a great leap to see how brain wiring early in the developmental process may go wrong in these pathological cases." Funding for this review was provided by DFG (the German Research Foundation). Neuron (@NeuroCellPress), published by Cell Press, is a bimonthly journal that has established itself as one of the most influential and relied upon journals in the field of neuroscience and one of the premier intellectual forums of the neuroscience community. It publishes interdisciplinary articles that integrate biophysical, cellular, developmental, and molecular approaches with a systems approach to sensory, motor, and higher-order cognitive functions. Visit: http://www. . To receive Cell Press media alerts, contact press@cell.com.


Graedel T.E.,Yale University | Graedel T.E.,Stellenbosch Institute for Advanced Study | Harper E.M.,Yale University | Nassar N.T.,Yale University | And 3 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

Imbalances between metal supply and demand, real or anticipated, have inspired the concept of metal criticality. We here characterize the criticality of 62 metals and metalloids in a 3D "criticality space" consisting of supply risk, environmental implications, and vulnerability to supply restriction. Contributing factors that lead to extreme values include high geopolitical concentration of primary production, lack of available suitable substitutes, and political instability. The results show that the limitations for many metals important in emerging electronics (e.g., gallium and selenium) are largely those related to supply risk; those of platinum group metals, gold, and mercury, to environmental implications; and steel alloying elements (e.g., chromium and niobium) as well as elements used in high-temperature alloys (e.g., tungsten and molybdenum), to vulnerability to supply restriction. The metals of most concern tend to be those available largely or entirely as byproducts, used in small quantities for highly specialized applications, and possessing no effective substitutes.


De Mello Koch R.,University of Witwatersrand | De Mello Koch R.,Stellenbosch Institute for Advanced Study | Dessein M.,University of Witwatersrand | Giataganas D.,University of Witwatersrand | Mathwin C.,University of Witwatersrand
Journal of High Energy Physics | Year: 2011

We study the action of the dilatation operator on restricted Schur polynomials labeled by Young diagrams with p long columns or p long rows. A new version of Schur- Weyl duality provides a powerful approach to the computation and manipulation of the symmetric group operators appearing in the restricted Schur polynomials. Using this new technology, we are able to evaluate the action of the one loop dilatation operator. The result has a direct and natural connection to the Gauss Law constraint for branes with a compact world volume. We find considerable evidence that the dilatation operator reduces to a decoupled set of harmonic oscillators. This strongly suggests that integrability in N = 4 super Yang-Mills theory is not just a feature of the planar limit, but extends to other large N but non-planar limits. © 2011 SISSA.


Haus S.,University of Rostock | Jabbari S.,University of Nottingham | Millat T.,University of Rostock | Janssen H.,University of Rostock | And 5 more authors.
BMC Systems Biology | Year: 2011

Background: Clostridium acetobutylicum is an anaerobic bacterium which is known for its solvent-producing capabilities, namely regarding the bulk chemicals acetone and butanol, the latter being a highly efficient biofuel. For butanol production by C. acetobutylicum to be optimized and exploited on an industrial scale, the effect of pH-induced gene regulation on solvent production by C. acetobutylicum in continuous culture must be understood as fully as possible.Results: We present an ordinary differential equation model combining the metabolic network governing solvent production with regulation at the genetic level of the enzymes required for this process. Parameterizing the model with experimental data from continuous culture, we demonstrate the influence of pH upon fermentation products: at high pH (pH 5.7) acids are the dominant product while at low pH (pH 4.5) this switches to solvents. Through steady-state analyses of the model we focus our investigations on how alteration in gene expression of C. acetobutylicum could be exploited to increase butanol yield in a continuous culture fermentation.Conclusions: Incorporating gene regulation into the model of solvent production by C. acetobutylicum enables an accurate representation of the pH-induced switch to solvent production to be obtained and theoretical investigations of possible synthetic-biology approaches to be pursued. Steady-state analyses suggest that, to increase butanol yield, alterations in the expression of single solvent-associated genes are insufficient; a more complex approach targeting two or more genes is required. © 2011 Haus et al; licensee BioMed Central Ltd.


Shadgan B.,University of British Columbia | Macnab A.,University of British Columbia | Macnab A.,Stellenbosch Institute for Advanced Study | Stothers L.,University of British Columbia | Kajbafzadeh A.M.,Tehran University of Medical Sciences
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2014

Background: Torsion of the testis compromises blood flow through the spermatic cord; testicular ischemia results which if not diagnosed promptly and corrected surgically irrevocably damages the testis. Current diagnostic modalities aimed at rationalizing surgical exploration by demonstrating interruption of spermatic cord blood flow or testicular ischemia have limited applicability. Near infrared spectroscopy (NIRS) offers a non-invasive optical method for detection of ischemia; continuous wave and frequency domain devices have been used experimentally; no device customized for clinical use has been designed. Methods: A miniature spatially resolved NIRS device with light emitting diode light source was applied over the right and left spermatic cord and the difference in oxygen saturation between the two sides measured. Results: In a 14-month old boy with a history of unilateral testicular pain color Doppler ultrasonography was equivocal but the NIRS-derived tissue oxygen saturation index (TSI) was significantly reduced on the left side. Confirmation of torsion of the left testicle was made surgically. Conclusions: Spatially resolved NIRS monitoring of spermatic cord oxygen saturation is feasible in children, adding to prior studies of testicular oxygen saturation in adults. Customized device design and further clinical trials would enhance the applicability of NIRS as a diagnostic entity for torsion. © 2014 SPIE.


Macnab A.J.,University of British Columbia | Macnab A.J.,Stellenbosch Institute for Advanced Study | Gagnon F.A.,University of British Columbia | Stewart D.,Griffith University
Health Education | Year: 2014

Purpose: The purpose of this paper is to summarize a consensus statement generated on the current challenges, strategies, and potential of health promoting schools (HPS) at a 2011 colloquium at the Stellenbosch Institute for Advanced Study where 40 people from five continents came together to share their global and regional experience surrounding the World Health Organization (WHO) HPS model. Design/methodology/approach: Using the consensus as its foundation, this review summarizes the underlying educational and social science concepts and factors that contribute to success or failure of HPS, and incorporates peer reviewed papers based on invited presentations at the colloquium and key related literature. Findings: HPS increase knowledge and develop behaviors that benefit the health of children, such schools are also an investment in the well-being of the larger community. Importantly for their long-term psychological health "resilience" is generated by effective HPS programs. Professional development initiatives within schools can catalyze greater absorption of the healthy school approach and focus on best practices. Promotion, support, and evaluation of programs are aided by award schemes and oversight by local or national agencies. And significant educational benefits are accrued for trainees from centers of higher learning involved in HPS program delivery. Practical implications: Educational initiatives that utilize the relative simplicity, low cost, and inherent flexibility of the HPS model can address many significant issues facing today's children. HPS offer an innovative and participatory way to increase the likelihood of the next generation becoming aware of practical ways to positively influence their lifestyle and future well-being. Successful programs are usually those that are relevant, resonate with students, and engage school communities so that they choose to "own" and sustain their program. Originality/value: The consensus statement provides a benchmark of the current status of HPS, and outlines future directions for this model of health promotion. © Emerald Group Publishing Limited.


MacNab A.J.,University of British Columbia | MacNab A.J.,Stellenbosch Institute for Advanced Study | Stothers L.S.,University of British Columbia | Shadgan B.,University of British Columbia
Advances in Urology | Year: 2012

The current literature indicates that lower urinary tract symptoms (LUTSs) related to benign prostatic hyperplasia (BPH) have a heterogeneous pathophysiology. Pressure flow studies (UDSs) remain the gold standard evaluation methodology for such patients. However, as the function of the detrusor muscle depends on its vasculature and perfusion, the underlying causes of LUTS likely include abnormalities of detrusor oxygenation and hemodynamics, and available treatment options include agents thought to act on the detrusor smooth muscle and/or vasculature. Hence, near infrared spectroscopy (NIRS), an established optical methodology for monitoring changes in tissue oxygenation and hemodynamics, has relevance as a means of expanding knowledge related to the pathophysiology of BPH and potential treatment options. This methodological report describes how to conduct simultaneous NIRS monitoring of detrusor oxygenation and hemodynamics during UDS, outlines the clinical implications and practical applications of NIRS, explains the principles of physiologic interpretation of NIRS voiding data, and proposes an exploratory hypothesis that the pathophysiological causes underlying LUTS include detrusor dysfunction due to an abnormal hemodynamic response or the onset of oxygen debt during voiding. © 2012 Andrew J. Macnab et al.


Shadgan B.,University of British Columbia | Afshar K.,University of British Columbia | Stothers L.,University of British Columbia | Macnab A.,University of British Columbia | Macnab A.,Stellenbosch Institute for Advanced Study
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2010

Background: Continuous wave near-infrared spectroscopy (NIRS) can monitor chromophore change in the bladder detrusor muscle during voiding; oxygenation and hemodynamic data derived differ in health and disease. Application of wireless NIRS for evaluation of voiding dysfunction would benefit children. Methods: Subjects: 20 children (4-17 yrs) [5 normal, 15 with urinary tract pathology]. Instrumentation: self-contained device weight 84 gm; 3 paired light emitting diodes (760/850 nm) in a spatially resolved configuration; source-detector separation distances (30, 35 and 40 mm); silicon photodiode detector; and Bluetooth®. Procedure: Transcutaneous monitoring (midline abdominal skin 2 cm above pubis) during spontaneous voiding (bladder contraction) of oxygenated (O2Hb), deoxygenated (HHb) and total hemoglobin (tHb) and tissue oxygen saturation index (TSI %) at 10 Hz. Results: All 20 trials produced clear graphic data with no movement effect evident. Comparison of patterns of chromophore change between normal and symptomatic subjects revealed trend differences in O2Hb and tHb. (Normal positive; Symptomatic negative, and TSI% fell in symptomatic group). Conclusions: Wireless NIRS is technically feasible in ambulant children. Negative trends in chromophore concentration and falls in TSI% suggest a hemodynamic impairment may underlie some forms of voiding dysfunction, with abnormal physiology involving the microcirculation possibly resulting in muscle fatigue during voiding. © 2010 Copyright SPIE - The International Society for Optical Engineering.


Morgenthau A.,Ryerson University | Nicolae A.M.,Ryerson University | Laursen A.E.,Ryerson University | Foucher D.A.,Ryerson University | And 3 more authors.
Biofouling | Year: 2012

Sodium dichloroisocyanurate (NaDCC) is a chemical agent that acts against microorganisms in a manner similar to that of sodium hypochlorite by releasing free available chlorine. NaDCC has been approved by the WHO for the emergency treatment of water and by the US EPA for routine treatment of water. Previous studies assessing the effectiveness of NaDCC for the treatment of water implied that NaDCC should have a wide array of disinfecting effects beyond the treatment of planktonic cells in potable water. In this study the biocidal effects of NaDCC against Pseudomonas aeruginosa cells in different growth modes including planktonic cells and biofilms were explored. The data showed that a 60% dilution of the standard NaDCC solution was effective in the treatment of both P. aeruginosa planktonic cells and biofilms. © 2012 Copyright Taylor and Francis Group, LLC.


Ronan P.,Ryerson University | William Yeung C.,Ryerson University | Schellenberg J.,University of Manitoba | Sparling R.,University of Manitoba | And 3 more authors.
Bioresource Technology | Year: 2013

The use of microbial communities in the conversion of cellulosic materials to bio-ethanol has the potential to improve the economic competitiveness of this biofuel and subsequently lessen our dependency on fossil fuel-based energy sources. Interactions between functionally different microbial groups within a community can expand habitat range, including the creation of anaerobic microenvironments. Currently, research focussing on exploring the nature of the interactions occurring during cellulose degradation and ethanol production within mixed microbial communities has been limited. The aim of this study was to enrich and characterize a cellulolytic bacterial community, and determine if ethanol is a major soluble end-product. Cellulolytic activity by the community was observed in both non-reduced and pre-reduced media, with ethanol and acetate being major fermentation products. Similar results were obtained when sterile wastewater extract was provided as nutrient. Several community members showed high similarity to Clostridium species with overlapping metabolic capabilities, suggesting clostridial functional redundancy. © 2012 Elsevier Ltd.

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