Stereoelectronic effects on the binding of neutral Lewis bases to CdSe nanocrystals

Using P-31 nuclear magnetic resonance (NMR) spectroscopy, we monitor the competition between tri-nbutylphosphine (Bu3P) and various amine and phosphine ligands for the surface of chloride terminated CdSe nanocrystals. Distinct P-31 NMR signals for free and bound phosphine ligands allow the surface ligand coverage to be measured in phosphine solution. Ligands with a small steric profile achieve higher surface coverages (Bu3P = 0.5 nm(-2), Me2P-n-octyl = 2.0 nm(-2), NH2Bu = >3 nm(-2)) and have greater relative binding affinity for the nanocrystal (binding affinity: Me3P > Me2P -n-octyl similar to Me2P -n-octadecyl > Et3P > Bu3P). Among phosphines, only Bu 3 P and Me2P-n-octyl support a colloidal dispersion, allowing a relative surface binding affinity (K-rel) to be estimated in that case (K-rel = 3.1). The affinity of the amine ligands is measured by the extent to which they displace Bu3P from the nanocrystals (K-rel: H2NBu similar to N-n-butylimidazole > 4-ethylpyridine > Bu3P similar to HNBu2 > Me2NBu > Bu3N). The affinity for the CdSe surface is greatest among soft, basic donors and depends on the number of each ligand that bind. Sterically unencumbered ligands such as imidazole, pyridine, and n-alkylamines can therefore outcompete stronger donors such as alkylphosphines. The influence of repulsive interactions between ligands on the binding affinity is a consequence of the high atom density of binary semiconductor surfaces. The observed behavior is distinct from the self-assembly of straight-chain surfactants on gold and silver where the ligands are commensurate with the underlying lattice and attractive interactions between aliphatic chains strengthen the binding

Algorithms, Automation, and News

This special issue examines the growing importance of algorithms and automation in the gathering, composition, and distribution of news. It connects a long line of research on journalism and computation with scholarly and professional terrain yet to be explored. Taken as a whole, these articles share some of the noble ambitions of the pioneering publications on ‘reporting algorithms’, such as a desire to see computing help journalists in their watchdog role by holding power to account. However, they also go further, firstly by addressing the fuller range of technologies that computational journalism now consists of: from chatbots and recommender systems, to artificial intelligence and atomised journalism. Secondly, they advance the literature by demonstrating the increased variety of uses for these technologies, including engaging underserved audiences, selling subscriptions, and recombining and re-using content. Thirdly, they problematize computational journalism by, for example, pointing out some of the challenges inherent in applying AI to investigative journalism and in trying to preserve public service values. Fourthly, they offer suggestions for future research and practice, including by presenting a framework for developing democratic news recommenders and another that may help us think about computational journalism in a more integrated, structured manner

Building Bridges: Improving Extension Support to Organic Growers in North Georgia

Organic agriculture has the potential to improve the environmental performance of U.S. agriculture, supporting increasing food demand and diversification of food consumption while improving the quality of ecosystems. Organic growers are challenged by a lack of Cooperative Extension agent support as agents have not served organic growers to the same extent as conventional growers nationwide. Rogers’ (2003) diffusion of innovations theory guided our phenomenological inquiry to explore (a) what agents experienced while supporting organic growers, and (b) how agents experienced providing support to organic growers in north Georgia. According to participants, the essence of the support offered to organic growers was an uneven bridge. Agents were willing to provide growers with the resources to support organic production; however, they lacked theoretical and empirical knowledge regarding organic agricultural production that would enable them to establish stronger relationships with growers. Findings from the study and the uneven bridge metaphor led to an original model to assist Extension agents in better serving the organic agricultural community

Farming the Iveragh uplands: A tale of humans and nature

The rugged beauty of the Iveragh peninsula has fascinated many a passing visitor and never fails to make some of us linger or stay for good. For those who need proof of the area’s uniqueness, a variety of national and European designations provide ample attestation of the splendour of Iveragh’s scenery, the diversity of its landscape and its heritage. Being surrounded on three sides by the Atlantic, Iveragh is the largest and most geographically isolated peninsula in Ireland whose western extremity, the Great Skellig, forms the westernmost point of Europe. Despite its maritime location, Iveragh’s character is fundamentally determined by the mountains, valleys and streams that form the peninsula’s interior—the bequest of a landscape sculpted by ice thousands of years ago (Crowley and Sheehan, 2009). Distinctive mountain scene in the Bridia Valley, Glencar Perhaps most distinctive, however, are the extensive blanket bogs and upland heather moorlands that cover most of the peninsula and captivate the imagination with the wild and austere appeal of an area where life did not change much for man and beast until relatively recently. Having come into existence in the wake of woodland clearances, the cutting of vegetation for fuel and the harvesting of crops for food and fiber by Neolithic farmers in the first and second millennium BC, this unique cultural landscape continues to be managed by traditional farmers and their animals to the present day. The value of areas such as Iveragh as repositories of a unique flora and fauna has long been recognized, but they have entered a period of major transformation as the agricultural economy that lay behind them no longer exists (Webb, 1998). The single largest danger is that farming communities may not survive the present discussion of how competitive European agriculture should be, as under present market conditions they are unable to compete without fundamentally changing their way of farming (Luick, 1998). The last 10 years have seen a growing debate over the future of areas like the Iveragh peninsula that may be ‘marginal’ in agricultural terms, but that are quite essential to life in Europe as we know and cherish it. Upland farmed landscapes provide clean water, maintain a rich plant and animal life and help to keep families in regions that offer few alternative employment opportunities – at the same time as attracting millions of tourists each year. The Caragh in Glencar—one of Europe’s cleanest rivers. Such areas, also termed high nature value farmland, cover about 25% of all agricultural land in Ireland and include, besides Iveragh, other parts of Kerry, Connemara, Mayo, Donegal, the Comeraghs, Wicklow, the Burren and the offshore Islands. The farming systems of these areas are characterised by extensive mixed livestock grazing and little agro-chemical inputs combined with labour-intensive management practices. Without dedicated farmers and their families, the character of these areas would change completely leading to the disappearance of unique cultural landscapes with effects such as rural depopulation and the loss of local communities. Already farming systems have changed substantially with livestock being concentrated on better quality land while marginal areas are being abandoned. Along with this, there are changes in the animals being farmed. The traditional Scotch Blackface sheep are increasingly crossed with or replaced by lowland breeds to satisfy market demands for heavy lamb. This has led to a softening in sheep and the fear among farmers that the traditional grazers of the uplands may be extinct in years to come. Going, too, is the use of the native rustic Kerry cow that grazed the rough Farming the Iveragh Uplands grasses, bracken, gorse and soft rushes in the winter - growth that sheep cannot control. Unsurprisingly, this disruption over a relatively short time, in what was formerly a sustainable relationship between farming and nature, will have implications for the area’s flora and fauna. Some of the repercussions are obvious; others need to be researched in more depth if appropriate solutions are to be formulated. It is now a stated objective of EU environment and rural development policy to maintain and conserve traditional farming systems like the one practised on Iveragh. Beyond acknowledging the importance of traditional farming for nature conservation and local livelihoods, it is necessary to understand how such farming systems function and to determine how the inevitable process of change can be redirected to provide a way of life that is socially and economically rewarding for farm families while preserving the farming practices necessary for Iveragh’s unique landscape to persist into the future. In this light, University College Cork (UCC) in conjunction with the Environmental Research Institute (ERI) and funded by Science Foundation Ireland (SFI) initiated BioUp, a 3 year research programme to investigate the upland farming system and rich biodiversity associated with it. Managing rural change in the uplands calls for the active involvement of many stakeholders, including farmers and agricultural advisory groups, land owners, conservation groups, forestry, tourism, and local authorities. In the BioUp project, researchers and stakeholders worked closely together. It is hoped that this will help to obtain a better understanding of the social, economic and environmental challenges facing Iveragh and promote greater public appreciation of the indispensable contributions made by farm families to maintaining our unique heritage - a service that has gone unappreciated too long

The SDSS-2MASS-WISE Ten Dimensional Stellar Color Locus

We present the fiducial main sequence stellar locus traced by 10 photometric colors observed by SDSS, 2MASS, and WISE. Median colors are determined using 1,052,793 stars with r-band extinction less than 0.125. We use this locus to measure the dust extinction curve relative to the r-band, which is consistent with previous measurements in the SDSS and 2MASS bands. The WISE band extinction coefficients are larger than predicted by standard extinction models. Using 13 lines of sight, we find variations in the extinction curve in H, Ks, and WISE bandpasses. Relative extinction decreases towards Galactic anti-center, in agreement with prior studies. Relative extinction increases with Galactic latitude, in contrast to previous observations. This indicates a universal mid-IR extinction law does not exist due to variations in dust grain size and chemistry with Galactocentric position. A preliminary search for outliers due to warm circumstellar dust is also presented, using stars with high signal-to-noise in the W3-band. We find 199 such outliers, identified by excess emission in Ks-W3. Inspection of SDSS images for these outliers reveals a large number of contaminants due to nearby galaxies. Six sources appear to be genuine dust candidates, yielding a fraction of systems with infrared excess of 0.12$\pm$0.05%.Comment: 11 pages, 10 figures, MNRAS Accepted. Tables 1 and 2 available online: https://github.com/jradavenport/wise_locu

Promotility Action of the Probiotic Bifidobacterium lactis HN019 Extract Compared with Prucalopride in Isolated Rat Large Intestine

Copyright © 2017 Dalziel, Anderson, Peters, Lynch, Spencer, Dekker and Roy. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.Attention is increasingly being focussed on probiotics as potential agents to restore or improve gastrointestinal (GI) transit. Determining mechanism of action would support robust health claims. The probiotic bacterium Bifidobacterium lactis HN019 reduces transit time, but its mechanisms of action and effects on motility patterns are poorly understood. The aim of this study was to investigate changes in GI motility induced by an extract of HN019 on distinct patterns of colonic motility in isolated rat large intestine, compared with a known promotility modulator, prucalopride. The large intestines from male Sprague Dawley rats (3–6 months) were perfused with Kreb's buffer at 37°C in an oxygenated tissue bath. Isometric force transducers recorded changes in circular muscle activity at four independent locations assessing contractile propagation between the proximal colon and the rectum. HN019 extract was perfused through the tissue bath and differences in tension and frequency quantified relative to pre-treatment controls. Prucalopride (1 μM) increased the frequency of propagating contractions (by 75 ± 26%) in the majority of preparations studied (10/12), concurrently decreasing the frequency of non-propagating contractions (by 50 ± 11%). HN019 extract had no effect on contractile activity during exposure (n = 8). However, following wash out, contraction amplitude of propagating contractions increased (by 55 ± 18%) in the distal colon, while the frequency of non-propagating proximal contractions decreased by 57 ± 7%. The prokinetic action of prucalopride increased the frequency of synchronous contractions along the length of colon, likely explaining increased colonic rate of transit in vivo. HN019 extract modified motility patterns in a different manner by promoting propagating contractile amplitude and inhibiting non-propagations, also demonstrating prokinetic activity consistent with the reduction of constipation by B. lactis HN019 in humans