Toward a sustainable global energy supply infrastructure : net energy balance and density considerations

This paper complements previous work on the economics of different energy resources by examining the growth potential of alternative electricity supply infrastructures as constrained by innate physical limits. Coal-fired generation meets the criteria of longevity (abundance of energy source) and scalability (effective capability to expand to the multi-terawatt level) which are critical for a sustainable energy supply chain, but it carries a very heavy carbon footprint. Renewables and nuclear power meet both the longevity and climate friendliness criteria. However, they vary in terms of their ability to deliver net energy at a scale needed for meeting a huge global energy demand. The low density of renewable resources for electricity generation and the current intermittency of many renewables limit their ability to achieve high rates of growth. And a significant global increase in nuclear power deployment could engender serious risks related to proliferation, safety, and waste disposal. Unlike renewable sources of energy, nuclear power is an unforgiving technology because human lapses and errors can have ecological and social impacts that are catastrophic and irreversible. The transition to a low carbon economy is likely to prove much more challenging than some optimists have claimed.Energy Production and Transportation,Climate Change Mitigation and Green House Gases,Energy and Environment,Environment and Energy Efficiency,Energy Demand

Towards a Sustainable Global Energy Supply Infrastructure: Net Energy Balance and Density Considerations

This paper employs a framework of dynamic energy analysis to model the growth potential of alternative electricity supply infrastructures as constrained by innate physical energy balance and dynamic response limits. Coal- red generation meets the criteria of longevity (abundance of energy source) and scalability (ability to expand to the multi-terawatt level) which are critical for a sustainable energy supply chain, but carries a very heavy carbon footprint. Renewables and nuclear power, on the other hand, meet both the longevity and environmental friendliness criteria. However, due to their substantially di¤erent energy densities and load factors, they vary in terms of their ability to deliver net excess energy and attain the scale needed for meeting the huge global energy demand. The low power density of renewable energy extraction and the intermittency of renewable ows limit their ability to achieve high rates of indigenous infrastructure growth. A signi cant global nuclear power deployment, on the other hand, could engender serious risks related to proliferation, safety, and waste disposal. Unlike renewable sources of energy, nuclear power is an unforgiving technology because human lapses and errors can have ecological and social impacts that are catastrophic and irreversible. Thus, the transition to a low carbon economy is likely to prove much more challenging than early optimists have claimed.dynamic energy analysis; alternative electricity supply; coal; nuclear energy

The Value of Regional Annual Nitrogen Needs Information for Wheat Producers in Oklahoma

Crop producers are increasingly interested in reducing nitrogen use without sacrificing yield. Technology is available for precise application at the sub-field level, but adoption has been sluggish. This paper estimates the relative profitability of a field level annual predictor of mid-season N requirements and a regional predictor of the same.nitrogen seeds, nitrogen use efficiency, precision agriculture, wheat, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Replicability of nitrogen recommendations from ramped calibration strips in winter wheat

Ramped calibration strips have been suggested as a way for grain producers to determine nitrogen needs more accurately. The strips use incrementally increasing levels of nitrogen and enable producers to conduct an experiment in each field to determine nitrogen needs. This study determines whether predictions from the program Ramp Analyzer 1.2 are replicable in Oklahoma hard red winter wheat (Triticum aestivum). Predictions are derived from 36 individual strips from on-farm experiments—two pairs of adjacent strips at each of nine winter wheat fields in Canadian County, OK. The two pairs of strips within each field were between 120 and 155 m apart. Each strip was analyzed three times during the 2006–2007 growing season. Nitrogen recommendations from Ramp Analyzer 1.2 are not correlated even for strips that were placed side by side, and recommendations from strips in the same field show no more homogeneity than randomly selected strips throughout the county. The results indicate that ramped calibration strips are unlikely to produce accurate nitrogen requirement predictions at any spatial scale, whether at the county level or for subsections of a single field. In contrast, a procedure that uses only measures from the plot with no nitrogen and the plot with the highest level of nitrogen applied does show replicability. Thus, improvements in the ramped calibration strip technology are needed if it is to become viable.Fertilizer; Nitrogen; Precision agriculture; Ramped calibration strip; Winter wheat

Energy landscapes of a hairpin peptide including NMR chemical shift restraints.

Methods recently introduced to improve the efficiency of protein structure prediction simulations by adding a restraint potential to a molecular mechanics force field introduce additional input parameters that can affect the performance. Here we investigate the changes in the energy landscape as the relative weight of the two contributions, force field and restraint potential, is systematically altered, for restraint functions constructed from calculated nuclear magnetic resonance chemical shifts. Benchmarking calculations were performed on a 12-residue peptide, tryptophan zipper 1, which features both secondary structure (a β-hairpin) and specific packing of tryptophan sidechains. Basin-hopping global optimization was performed to assess the efficiency with which lowest-energy structures are located, and the discrete path sampling approach was employed to survey the energy landscapes between unfolded and folded structures. We find that inclusion of the chemical shift restraints improves the efficiency of structure prediction because the energy landscape becomes more funnelled and the proportion of local minima classified as native increases. However, the funnelling nature of the landscape is reduced as the relative contribution of the chemical shift restraint potential is increased past an optimal value.This research was supported by the EPSRC and the ERC.This is the final version of the article. It first appeared from the Royal Society of Chemistry via http://dx.doi.org/10.1039/C5CP01259

Biostratigraphic utility of coiling direction in Miocene planktonic foraminiferal genus Paragloborotalia

Trochospiral planktonic foraminifera will coil either sinistral (left) or dextral (right). The prevalence of sinistral or dextral coiling can change through the stratigraphic range of morphospecies with a preference in coiling direction. A number of coiling shifts have been applied as secondary marker events through the Recent to late Miocene (~0–7 Ma) biochronology. However, no such events have been applied beyond this age despite a number of species being known to adopt preferential coiling directions. Here we investigate selected Miocene species within the genus Paragloborotalia. Previous work in the tropical to subtropical realm has shown that the mayeri–siakensis group undergoes a shift from random to sinistrally dominated coiling in the mid Miocene (~15 Ma). We extend the investigation to other Miocene paragloborotaliids in the low (IODP Sites U1337, U1338, ODP Sites 871 and 925), mid (JOIDES-3 hole) and high latitudes (ODP Site 747) in order to assess whether there is global synchronicity and if the change is unique to the mayeri-siakensis group. In addition, a number of outcrop samples from the Cipero and Lengua formations in southern Trinidad are quantitatively compared to previously published trends. Our results show that in the low-mid latitudes the coiling shift is at ~15.37 Ma within planktonic foraminiferal Zone M5 within both Paragloborotalia siakensis and Paragloborotalia continuosa. In the high latitudes the absence of paragloborotaliids through a portion of the mid Miocene interval prevents accurate dating of a shift from early forms showing random coiling to later paragloborotaliids adopting a sinistral preference. We also find two coiling changes in the genus Globorotalia at high latitude Site 747, from random to sinistral in the mid Miocene (15.14 Ma) and sinistral to dextral (10.02 Ma) in the late Miocene. We propose the recognition of a coiling change in Paragloborotalia as a secondary bioevent in the mid Miocene at 15.37 Ma, and a useful means for the recognition of the base of the Langhian. The coiling shift as a biostratigraphic marker is likely to be particularly useful in regions where the currently applied bioevents, namely the Praeorbulina–Orbulina lineage, is rare or poorly represented

Spatiotemporal effects of logging and fire on tall, wet temperate eucalypt forest birds

Forests globally are subject to disturbances such as logging and fire that create complex temporal variation in spatial patterns of forest cover and stand age. However, investigations that quantify temporal changes in biodiversity in response to multiple forms of disturbance in space and time are relatively uncommon. Over a 10-yr period, we investigated the response of bird species to spatiotemporal changes in forest cover associated with logging and wildfire in the mountain ash (Eucalyptus regnans) forests of southeastern Australia. Specifically, we examined how bird occurrence changed with shifts in the proportion of area burned or logged in a 4.5 km radius surrounding our 88 long-term field survey sites, each measuring 1 ha in size. Overall species richness was greatest in older forest patches, but declined as the amount of fire around each site increased. At the individual species level, 31 of the 37 bird species we modeled exhibited a negative response to the amount of fire in the surrounding landscape, while one species responded positively to fire. Only nine species exhibited signs of recovery in the 6 yr of surveys following the fire. Five species were more likely to be detected as the proportion of logged forest surrounding a site increased, suggesting a possible "concentration effect" with displaced birds moving into unlogged areas following harvesting of adjacent areas. We also identified relationships between the coefficients of life history attributes and spatiotemporal changes in forest cover and stand age. Large-bodied birds and migratory species were associated with landscapes subject to large amounts of fire in 2009. There were associations between old growth stands and small-bodied bird species and species that were not insectivores. Our study shows that birds in mountain ash forests are strongly associated with old growth stands and exhibit complex, time-dependent, and species-specific responses to landscape disturbance. Despite logging and fire both being high-severity perturbations, no bird species exhibited similar responses to fire and logging in the landscape surrounding our sites. Thus, species responses to one kind of landscape-scale disturbance are not readily predictable based on an understanding of the responses to another kind of (albeit superficially similar) disturbance.Threatened Species Recovery Hub of the National Environmental Science Program, Parks Victoria, and Victorian Government Department of Environment, Land, Water and Plannin

“Burn Down” Management of Winter Cereal Cover Crops for No-tillage Burley Tobacco Production

Recent developments in the design of no-till transplanters and significant improvements in weed control have made no-till tobacco production a feasible option for burley tobacco growers. No-till production reduces soil erosion when tobacco is grown on sloping land. This helps maintain the long term productivity of the soil and may provide the grower with more options for crop rotation, by allowing sloping land to be utilized for tobacco production

Narratives as Responses to Interpersonal Violence: The Case of HIV

This chapter examines how narratives can act as dialogic responses to physical interpersonal violence, affirming positive routes of response and helping to generate new routes of this kind. It also explores the limitations of narratives as responses to physical interpersonal violence, in situations where such violence is strongly related to economic and other resource constraints, and situations where it may be difficult to build commonalities between narrative responses. The chapter draws on my ongoing research, using semi-structured interviews, about people’s experiences of HIV support in South Africa, in 2001 and 2012, and on my analysis of narratives produced within these interviews, predominantly by women, about HIV-linked interpersonal physical violence, predominantly by men

The Escherichia coli RutR transcription factor binds at targets within genes as well as intergenic regions.

The Escherichia coli RutR protein is the master regulator of genes involved in pyrimidine catabolism. Here we have used chromatin immunoprecipitation in combination with DNA microarrays to measure the binding of RutR across the chromosome of exponentially growing E. coli cells. Twenty RutR-binding targets were identified and analysis of these targets generated a DNA consensus logo for RutR binding. Complementary in vitro binding assays showed high-affinity RutR binding to 16 of the 20 targets, with the four low-affinity RutR targets lacking predicted key binding determinants. Surprisingly, most of the DNA targets for RutR are located within coding segments of the genome and appear to have little or no effect on transcript levels in the conditions tested. This contrasts sharply with other E. coli transcription factors whose binding sites are primarily located in intergenic regions. We suggest that either RutR has yet undiscovered function or that evolution has been slow to eliminate non-functional DNA sites for RutR because they do not have an adverse effect on cell fitness