Solar modulation in surface atmospheric electricity

The solar wind modulates the flux of galactic cosmic rays impinging on Earth inversely with solar activity. Cosmic ray ionisation is the major source of air’s electrical conductivity over the oceans and well above the continents. Differential solar modulation of the cosmic ray energy spectrum modifies the cosmic ray ionisation at different latitudes,varying the total atmospheric columnar conductance. This redistributes current flow in the global atmospheric electrical circuit, including the local vertical current density and the related surface potential gradient. Surface vertical current density and potential gradient measurements made independently at Lerwick Observatory,Shetland,from 1978 to 1985 are compared with modelled changes in cosmic ray ionisation arising from solar activity changes. Both the lower troposphere atmospheric electricity quantities are significantly increased at cosmic ray maximum(solar minimum),with a proportional change greater than that of the cosmic ray change

Determining how atmospheric carbon dioxide concentrations have changed during the history of the Earth

The reconstruction of ancient atmospheric carbon dioxide concentrations is essential to understanding the history of the Earth and life. It is also an important guide to identifying the sensitivity of the Earth system to this greenhouse gas and, therefore, constraining its future impact on climate. However, determining the concentration of CO2 in ancient atmospheres is a challenging endeavour requiring the application of state-of-the-art analytical chemistry to geological materials, underpinned by an understanding of photosynthesis and biochemistry. It is truly an interdisciplinary challenge

A Δ11 desaturase gene genealogy reveals two divergent allelic classes within the European corn borer (Ostrinia nubilalis)

<p>Abstract</p> <p>Background</p> <p>Moth pheromone mating systems have been characterized at the molecular level, allowing evolutionary biologists to study how changes in protein sequence or gene expression affect pheromone phenotype, patterns of mating, and ultimately, the formation of barriers to gene exchange. Recent studies of <it>Ostrinia </it>pheromones have focused on the diversity of sex pheromone desaturases and their role in the specificity of pheromone production. Here we produce a Δ11 desaturase genealogy within <it>Ostrinia nubilalis</it>. We ask what has been the history of this gene, and whether this history suggests that changes in Δ11 desaturase have been involved in the divergence of the E and Z <it>O. nubilalis </it>pheromone strains.</p> <p>Results</p> <p>The Δ11 desaturase gene genealogy does not differentiate <it>O. nubilalis</it> pheromone strains. However, we find two distinct clades, separated by 2.9% sequence divergence, that do not sort with pheromone strain, geographic origin, or emergence time. We demonstrate that these clades do not represent gene duplicates, but rather allelic variation at a single gene locus.</p> <p>Conclusions</p> <p>Analyses of patterns of variation at the Δ11 desaturase gene in ECB suggest that this enzyme does not contribute to reproductive isolation between pheromone strains (E and Z). However, our genealogy reveals two deeply divergent allelic classes. Standing variation at loci that contribute to mate choice phenotypes may permit novel pheromone mating systems to arise in the presence of strong stabilizing selection.</p

EST analysis of male accessory glands from Heliconius butterflies with divergent mating systems

<p>Abstract</p> <p>Background</p> <p><it>Heliconius </it>butterflies possess a remarkable diversity of phenotypes, physiologies, and behaviors that has long distinguished this genus as a focal taxon in ecological and evolutionary research. Recently <it>Heliconius </it>has also emerged as a model system for using genomic methods to investigate the causes and consequences of biological diversity. One notable aspect of <it>Heliconius </it>diversity is a dichotomy in mating systems which provides an unusual opportunity to investigate the relationship between sexual selection and the evolution of reproductive proteins. As a first step in pursuing this research, we report the generation and analysis of expressed sequence tags (ESTs) from the male accessory gland of <it>H. erato </it>and <it>H. melpomene</it>, species representative of the two mating systems present in the genus <it>Heliconius</it>.</p> <p>Results</p> <p>We successfully sequenced 933 ESTs clustering into 371 unigenes from <it>H. erato </it>and 1033 ESTs clustering into 340 unigenes from <it>H. melpomene</it>. Results from the two species were very similar. Approximately a third of the unigenes showed no significant BLAST similarity (E-value <10^-5) to sequences in GenBank's non-redundant databases, indicating that a large proportion of novel genes are expressed in <it>Heliconius </it>male accessory glands. In both species only a third of accessory gland unigenes were also found among genes expressed in wing tissue. About 25% of unigenes from both species encoded secreted proteins. This includes three groups of highly abundant unigenes encoding repetitive proteins considered to be candidate seminal fluid proteins; proteins encoded by one of these groups were detected in <it>H. erato </it>spermatophores.</p> <p>Conclusion</p> <p>This collection of ESTs will serve as the foundation for the future identification and evolutionary analysis of male reproductive proteins in <it>Heliconius </it>butterflies. These data also represent a significant advance in the rapidly growing collection of genomic resources available in <it>Heliconius </it>butterflies. As such, they substantially enhance this taxon as a model system for investigating questions of ecological, phenotypic, and genomic diversity.</p

Patterns, causes, and consequences of marine larval dispersal

Quantifying the probability of larval exchange among marine populations is key to predicting local population dynamics and optimizing networks of marine protected areas. The pattern of connectivity among populations can be described by the measurement of a dispersal kernel. However, a statistically robust, empirical dispersal kernel has been lacking for any marine species. Here, we use genetic parentage analysis to quantify a dispersal kernel for the reef fish Elacatinus lori, demonstrating that dispersal declines exponentially with distance. The spatial scale of dispersal is an order of magnitude less than previous estimates—the median dispersal distance is just 1.7 km and no dispersal events exceed 16.4 km despite intensive sampling out to 30 km from source. Overlaid on this strong pattern is subtle spatial variation, but neither pelagic larval duration nor direction is associated with the probability of successful dispersal. Given the strong relationship between distance and dispersal, we show that distance-driven logistic models have strong power to predict dispersal probabilities. Moreover, connectivity matrices generated from these models are congruent with empirical estimates of spatial genetic structure, suggesting that the pattern of dispersal we uncovered reflects long-term patterns of gene flow. These results challenge assumptions regarding the spatial scale and presumed predictors of marine population connectivity. We conclude that if marine reserve networks aim to connect whole communities of fishes and conserve biodiversity broadly, then reserves that are close in space (<10 km) will accommodate those members of the community that are short-distance dispersers.We thank Diana Acosta, Alben David, Kevin David, Alissa Rickborn, and Derek Scolaro for assistance with field work; Eliana Bondra for assistance with molecular work; and Peter Carlson for assistance with otolith work. We are grateful to Noel Anderson, David Lindo, Claire Paris, Robert Warner, Colleen Webb, and two anonymous reviewers for comments on this manuscript. This work was supported by National Science Foundation (NSF) Grant OCE-1260424, and C.C.D. was supported by NSF Graduate Research Fellowship DGE-1247312. All work was approved by Belize Fisheries and Boston University Institutional Animal Care and Use Committee. (OCE-1260424 - National Science Foundation (NSF); DGE-1247312 - NSF Graduate Research Fellowship)Published versio

Data Points and Duration for Estimating Fuel Consumption of a Diesel Engine

Accurate measurement of fuel consumption is required to quantify the efficiency of an engine or predict emissions. As part of a larger project, accurate instantaneous fuel consumption data was required for a John Deere 4045T diesel engine. While establishing test criteria, it became evident that literature did not provide clear recommendations on the number of data points or time duration for data collection, for a diesel engine. Fuel consumption tests were conducted using up to 15 data points of percent fuel rate and up to 15 min of data collection. Based on statistical analysis of test results, at least 2 data points (0% and 100% of fuel rate) and 2 min of data collection are recommended for similar fuel-injected, diesel engine fuel rate tests. When a nonfuel injected engine is used, the Hogan et al. (2007) recommendation of at least 3 data points and 3.5 min of data collection should be followed

Early Sowing and Irrigating of Rape Crops in Cool Temperate Environments Boosts Forage Yield Potential

Forage rape is commonly grown on Tasmanian dairy farms to provide feed during periods of low pasture growth and/or low nutritive value. In these regions, forage crops are generally sown between early spring and late autumn and are commonly rainfed, though farmers may apply a single irrigation at sowing. While the effect of water availability on forage yield has been well characterised for regions in north-western Tasmania (Neilsen 2005), there is a dearth of information for other regions in Tasmania. Hence, the objectives of this study were to identify optimal sowing times for, and determine the extent to which a single irrigation at sowing influences productivity of, rainfed brassica crops across the dairy regions of Tasmania

Cultural expectations of muscularity in men: The evolution of playgirl centerfolds

Abstract: Objective: We sought to assess whether cultural ideals of the male body, as illustrated by magazine models, have changed over the past 25 years. Method: We examined 115 male centerfold models in Playgirl magazine from 1973 to 1997. Using the models’ heights and weights quoted by the magazine, together with visual estimates of body fat, we calculated the body mass index (BMI) and fat-free mass index (FFMI) of each model. Results: The Playgirl centerfold models became increasingly “dense ” and more muscular over time, as indicated by the significant correlations between BMI, FFMI, and year of publication. Discussion: These observations, in combination with previous studies, suggest that cultural norms of the ideal male body are growing increasingly muscular. © 2000 by John Wiley &amp

Impact of Grazing on the Silage Yield of Forage Oat Crops

Winter forage oat crops are increasing in acreage on Tasmanian dairy farms. Such crops can be grazed multiple times during vegetative development in winter then later harvested for silage at the booting or soft dough growth stages in spring. Although effects of grazing on grain yield of winter cereal crops have been well characterised (Harrison et al. 2011), little research has been conducted on the influence of grazing on the forage and silage yield potential of oats grown in Tasmania. We aimed to explore the influence of grazing management on the yields of forage for grazing and ensiling of oat crops using a biophysical crop model

The role of guanxi networks in the performance of women-led firms in China

This exploratory paper examines how knowledge acquired via guanxi (networks and connections) have enabled women-led firms in China to overcome a number of significant barriers and challenges in order to start and grow a successful business. We draw upon two case studies, in order to illustrate how they have utilized guanxi as a means of overcoming these barriers. We investigate the way in which guanxi facilitates the business owner in engaging in a process of entrepreneurial learning (Harrison and Leitch 2005; Politis, 2008) – and making connections and contacts – by which she is able to improve the firm’s performance. Further research is necessary to build upon a small number of studies that have already cleared the ground in terms of guanxi. More reliable and country-wide, but disaggregated, statistics on small businesses would be a welcome start, including information on their owner-manager’s or owner-managers’ gender