Paradoxes of leadership: Contingencies and critical learning

No Abstract.South African Journal of Education Vol. 27(3) 2007: pp. 377-39

Current Efficiency, Dielectric Measurements & Ion Mobility Studies of Anodic Oxide Films Formed on Tantalum in Aqueous Electrolytes

198-20

Measuring soil processes in agricultural research

Soil and crop management strategies (e.g., tillage, bunding, cropping intensity, and crop sequencing) are location- and season-specific in the way they affect soil processes and resource utilization by crops. Research findings on these effects therefore need to be modeled if they are to be extrapolated to other locations wi th similar soils and climatic conditions. This manual presents practical methods for assessing management effects on such soil processes as water infiltration and erosion by water, and on water, air, and nutrient use by crops. It covers the basic elements of soil physical characterization, and deals principally with the role of soil structure on water infiltration and percolation, heat flow, aeration, and the mobility of roots and soil microorganisms. The authors discuss the agronomic and engineering practices that affect soil processes; and the effects of such strategies as contour cultivation, organic and inorganic amendments, watershed management, and soil surface manipulations are emphasized

Mantle redox state drives outgassing chemistry and atmospheric composition of rocky planets

Volcanic degassing of planetary interiors has important implications for their corresponding atmospheres. The oxidation state of rocky interiors affects the volatile partitioning during mantle melting and subsequent volatile speciation near the surface. Here we show that the mantle redox state is central to the chemical composition of atmospheres while factors such as planetary mass, thermal state, and age mainly affect the degassing rate. We further demonstrate that mantle oxygen fugacity has an effect on atmospheric thickness and that volcanic degassing is most efficient for planets between 2 and 4 Earth masses. We show that outgassing of reduced systems is dominated by strongly reduced gases such as H2, with only smaller fractions of moderately reduced/oxidised gases (CO, H2O). Overall, a reducing scenario leads to a lower atmospheric pressure at the surface and to a larger atmospheric thickness compared to an oxidised system. Atmosphere predictions based on interior redox scenarios can be compared to observations of atmospheres of rocky exoplanets, potentially broadening our knowledge on the diversity of exoplanetary redox states

Exercising D. melanogaster modulates the mitochondrial proteome and physiology - the effect on lifespan depends upon age and sex

Ageing is a major risk factor for many of the most prevalent diseases, including neurodegenerative disease, cancer and heart disease. As the global population continues to age, behavioural interventions that can promote healthy ageing will improve quality of life and relieve the socio-economic burden that comes with an aged society. Exercise is recognised as an effective intervention against many diseases of ageing, but we don’t know the stage in an individual’s lifetime in which exercise is most effective at promoting healthy ageing and whether it has a direct effect on lifespan. We exercised w 1118 Drosophila melanogaster, interrogating effects of sex and group size, at different stages of their lifetime and recorded their lifespan. Climbing scores at 30 days were measured to record differences in fitness in response to exercise. We also assessed the mitochondrial proteome of w 1118 Drosophila that had been exercised for one week, alongside mitochondrial respiration measured using High-Resolution Respirometry, to determine changes in mitochondrial physiology in response to exercise. We found that age-targeted exercise interventions improve lifespan in male and female Drosophila, and grouped males exercised in late life had improved climbing scores, when compared with those exercised throughout their entire lifespan. The proteins of the electron transport chain were significantly upregulated in expression after one week of exercise, and complex II linked respiration was significantly increased in exercised Drosophila. Taken together our study provides a basis to test specific proteins and complex II of the respiratory chain as important effectors of exercise induced healthy ageing

Public Health and the Built Environment: Historical, Empirical, and Theoretical Foundations for an Expanded Role

In 2000, the Center for Disease Control and Prevention\u27s National Center for Environmental Health issued a report that explored some of the ways in which sprawl impacts public health. The report has generated great interest, and state health officials are beginning to discuss the relationship between land use and public health. The CDC report has also produced a backlash. For example, the Southern California Building Industry Association labeled the report a ludicrous sham and argued that the CDC should stick to fighting physical diseases, not defending political ones. In this environment, it is understandable if the CDC looks to such critiques as simply the latest partisan recruit to a political debate. But critics of the CDC\u27s efforts in this area may substantially overstate their case in the other direction. There is now and has long been a demonstrated connection between health, including physical disease, and the built environment. Moreover, government has intervened in the past in response to this connection and it continues to do so. While neither past practice nor current evidence make government intervention inevitable, this paper argues that such intervention is appropriate and supported by theory as well as history and empirical evidence

Mantle redox state drives outgassing chemistry and atmospheric composition of rocky planets

Volcanic degassing of planetary interiors has important implications for their corresponding atmospheres. The oxidation state of rocky interiors affects the volatile partitioning during mantle melting and subsequent volatile speciation near the surface. Here we show that the mantle redox state is central to the chemical composition of atmospheres while factors such as planetary mass, thermal state, and age mainly affect the degassing rate. We further demonstrate that mantle oxygen fugacity has an effect on atmospheric thickness and that volcanic degassing is most efficient for planets between 2 and 4 Earth masses. We show that outgassing of reduced systems is dominated by strongly reduced gases such as H2, with only smaller fractions of moderately reduced/oxidised gases (CO, H2O). Overall, a reducing scenario leads to a lower atmospheric pressure at the surface and to a larger atmospheric thickness compared to an oxidised system. Atmosphere predictions based on interior redox scenarios can be compared to observations of atmospheres of rocky exoplanets, potentially broadening our knowledge on the diversity of exoplanetary redox states

Mantle redox state drives outgassing chemistry and atmospheric composition of rocky planets.

Funder: German Research Foundation (DFG) SFB-TRR 170 "Late Accretion onto Terrestrial Planets" (subprojects C5, C6) and projects Ts 17/2-1 and NO 1324/2-1Funder: Swiss National Foundation under grant PZ00P2 174028 and the National Center for Competence in Research PlanetSVolcanic degassing of planetary interiors has important implications for their corresponding atmospheres. The oxidation state of rocky interiors affects the volatile partitioning during mantle melting and subsequent volatile speciation near the surface. Here we show that the mantle redox state is central to the chemical composition of atmospheres while factors such as planetary mass, thermal state, and age mainly affect the degassing rate. We further demonstrate that mantle oxygen fugacity has an effect on atmospheric thickness and that volcanic degassing is most efficient for planets between 2 and 4 Earth masses. We show that outgassing of reduced systems is dominated by strongly reduced gases such as [Formula: see text], with only smaller fractions of moderately reduced/oxidised gases ([Formula: see text], [Formula: see text]). Overall, a reducing scenario leads to a lower atmospheric pressure at the surface and to a larger atmospheric thickness compared to an oxidised system. Atmosphere predictions based on interior redox scenarios can be compared to observations of atmospheres of rocky exoplanets, potentially broadening our knowledge on the diversity of exoplanetary redox states

Quantitative proteomic analysis of age-related subventricular zone proteins associated with neurodegenerative disease.

Aging is characterized by a progressive decline in the function of adult tissues which can lead to neurodegenerative disorders. However, little is known about the correlation between protein changes in the subventricular zone (SVZ) and neurodegenerative diseases with age. In the present study, neural stem cells (NSCs) were derived from the SVZ on postnatal 7 d, 1 m, and 12 m-old mice. With age, NSCs exhibited increased SA-β-gal activity and decreased proliferation and pool size in the SVZ zone, and were associated with elevated inflammatory chemokines and cytokines. Furthermore, quantitative proteomics and ingenuity pathway analysis were used to evaluate the significant age-related alterations in proteins and their functions. Some downregulated proteins such as DPYSL2, TPI1, ALDH, and UCHL1 were found to play critical roles in the neurological disease and PSMA1, PSMA3, PSMC2, PSMD11, and UCHL1 in protein homeostasis. Taken together, we have provided valuable insight into the cellular and molecular processes that underlie aging-associated declines in SVZ neurogenesis for the early detection of differences in gene expression and the potential risk of neurological disease, which is beneficial in the prevention of the diseases