Meltwater export of prokaryotic cells from the Greenland ice sheet

Microorganisms are flushed from the Greenland Ice Sheet (GrIS) where they may contribute towards the nutrient cycling and community compositions of downstream ecosystems. We investigate meltwater microbial assemblages as they exit the GrIS from a large outlet glacier, and as they enter a downstream river delta during the record melt year of 2012. Prokaryotic abundance, flux and community composition was studied, and factors affecting community structures were statistically considered. The mean concentration of cells exiting the ice sheet was 8.30 × 104 cells mL−1 and we estimate that ∼1.02 × 1021 cells were transported to the downstream fjord in 2012, equivalent to 30.95 Mg of carbon. Prokaryotic microbial assemblages were dominated by Proteobacteria, Bacteroidetes, and Actinobacteria. Cell concentrations and community compositions were stable throughout the sample period, and were statistically similar at both sample sites. Based on our observations, we argue that the subglacial environment is the primary source of the river-transported microbiota, and that cell export from the GrIS is dependent on discharge. We hypothesise that the release of subglacial microbiota to downstream ecosystems will increase as freshwater flux from the GrIS rises in a warming world

A large pseudoautosomal region on the sex chromosomes of the frog Silurana tropicalis

Sex chromosome divergence has been documented across phylogenetically diverse species, with amphibians typically having cytologically nondiverged (“homomorphic”) sex chromosomes. With an aim of further characterizing sex chromosome divergence of an amphibian, we used “RAD-tags” and Sanger sequencing to examine sex specificity and heterozygosity in theWestern clawed frog Silurana tropicalis (also known as Xenopus tropicalis). Our findings based on approximately 20 million genotype calls and approximately 200 polymerase chain reaction-amplified regions across multiple male and female genomes failed to identify a substantially sized genomic region with genotypic hallmarks of sex chromosome divergence, including in regions known to be tightly linked to the sex-determining region.Wealso foundthat expression andmolecular evolutionof genes linked to the sex-determining region did not differ substantially from genes in other parts of the genome. This suggests that the pseudoautosomal region, where recombination occurs, comprises a large portion of the sex chromosomes of S. tropicalis. These resultsmay in part explainwhy African clawed frogs have such a high incidence of polyploidization, shed light onwhy amphibians have a high rate of sex chromosome turnover, and raise questions about why homomorphic sex chromosomes are so prevalent in amphibians

A qualitative study of stakeholders' perspectives on the social network service environment

Over two billion people are using the Internet at present, assisted by the mediating activities of software agents which deal with the diversity and complexity of information. There are, however, ethical issues due to the monitoring-and-surveillance, data mining and autonomous nature of software agents. Considering the context, this study aims to comprehend stakeholders' perspectives on the social network service environment in order to identify the main considerations for the design of software agents in social network services in the near future. Twenty-one stakeholders, belonging to three key stakeholder groups, were recruited using a purposive sampling strategy for unstandardised semi-structured e-mail interviews. The interview data were analysed using a qualitative content analysis method. It was possible to identify three main considerations for the design of software agents in social network services, which were classified into the following categories: comprehensive understanding of users' perception of privacy, user type recognition algorithms for software agent development and existing software agents enhancement

Facilitating Organisational Fluidity with Computational Social Matching

Striving to operate in increasingly dynamic environments, organisations can be seen as fluid and communicative entities where traditional boundaries fade away and collaborations emerge ad hoc. To enhance fluidity, we conceptualise computational social matching as a research area investigating how to digitally support the development of mutually suitable compositions of collaborative ties in organisations. In practice, it refers to the use of data analytics and digital methods to identify features of individuals and the structures of existing social networks and to offer automated recommendations for matching actors. In this chapter, we outline an interdisciplinary theoretical space that provides perspectives on how interaction can be practically enhanced by computational social matching, both on the societal and organisational levels. We derive and describe three strategies for professional social matching: social exploration, network theory-based recommendations, and machine learning-based recommendations.Striving to operate in increasingly dynamic environments, organisations can be seen as fluid and communicative entities where traditional boundaries fade away and collaborations emerge ad hoc. To enhance fluidity, we conceptualise computational social matching as a research area investigating how to digitally support the development of mutually suitable compositions of collaborative ties in organisations. In practice, it refers to the use of data analytics and digital methods to identify features of individuals and the structures of existing social networks and to offer automated recommendations for matching actors. In this chapter, we outline an interdisciplinary theoretical space that provides perspectives on how interaction can be practically enhanced by computational social matching, both on the societal and organisational levels. We derive and describe three strategies for professional social matching: social exploration, network theory-based recommendations, and machine learning-based recommendations.Peer reviewe

Environmental regulation induced foreign direct investment

The last decade has witnessed a renewed interest in the relationship between environmental regulations and international capital flows. However, empirical studies have so far failed to find conclusive evidence for this so-called pollution haven or race to the bottom effect where foreign direct investment (FDI) is assumed to be attracted to low regulation countries, regions or states. In this paper we present a simple theoretical framework to demonstrate that greater stringency in environmental standards can lead to a strategic increase in capital inflows which we refer to as environmental regulation induced FDI. Our result reveals a possible explanation for the mixed results in the empirical literature and provides an illustration of the conditions under which environmental regulations in the host country can affect the location decision of foreign firms

Greenland melt drives continuous export of methane from the ice-sheet bed

Ice sheets are currently ignored in global methane budgets1,2. Although ice sheets have been proposed to contain large reserves of methane that may contribute to a rise in atmospheric methane concentration if released during periods of rapid ice retreat3,4, no data exist on the current methane footprint of ice sheets. Here we find that subglacially produced methane is rapidly driven to the ice margin by the efficient drainage system of a subglacial catchment of the Greenland ice sheet. We report the continuous export of methane-supersaturated waters (CH4(aq)) from the ice-sheet bed during the melt season. Pulses of high CH4(aq) concentration coincide with supraglacially forced subglacial flushing events, confirming a subglacial source and highlighting the influence of melt on methane export. Sustained methane fluxes over the melt season are indicative of subglacial methane reserves that exceed methane export, with an estimated 6.3 tonnes (discharge-weighted mean; range from 2.4 to 11 tonnes) of CH4(aq) transported laterally from the ice-sheet bed. Stable-isotope analyses reveal a microbial origin for methane, probably from a mixture of inorganic and ancient organic carbon buried beneath the ice. We show that subglacial hydrology is crucial for controlling methane fluxes from the ice sheet, with efficient drainage limiting the extent of methane oxidation5 to about 17 per cent of methane exported. Atmospheric evasion is the main methane sink once runoff reaches the ice margin, with estimated diffusive fluxes (4.4 to 28 millimoles of CH4 per square metre per day) rivalling that of major world rivers6. Overall, our results indicate that ice sheets overlie extensive, biologically active methanogenic wetlands and that high rates of methane export to the atmosphere can occur via efficient subglacial drainage pathways. Our findings suggest that such environments have been previously underappreciated and should be considered in Earth’s methane budget

Voices Raised, Issue 06

Included in this issue: Immaculate Mary; Grants augment women’s research; Mentoring grows; Women’s Studies take root in the neighborhood; Solution-oriented VP to retire; Muslim students strive to educate, support; Don’t let stress ruin your holidays; Dining services dishes up more than you’d expect; Marianist Images Across Campus; Confronting Disrespect: We Owe it to Each Other.https://ecommons.udayton.edu/wc_newsletter/1005/thumbnail.jp