Pollinator Community Homogenization and Pollination Services in Agroecosystems

Pollination, or the transfer of pollen to plant stigmas, is an essential part of plant reproduction. The term “pollination system” refers to the floral phenotype and pollinator of a given plant. Although angiosperms exhibit a variety of different pollination systems, most rely partially or completely on animals, particularly insects, to vector their pollen. In agricultural systems, understanding the pollination system of the crop species is necessary to produce an economically valuable yield. Moreover, agricultural management may affect pollination systems by altering the abundance, diversity, or function of the pollinator community. In natural ecosystems, there is a great diversity of pollinating insects. This pollinator diversity may be vulnerable to global change and land use. One concern is that land use change may homogenize these pollinator communities, which in turn might affect their pollination service to angiosperms. To better understand the effect of agriculture on the homogenization of pollinator communities, we conducted a survey of pollinator diversity in different land-use types in eastern Tennessee. We sampled flower-visiting (pollinating) insects from the landscape around experimental plots of plants native to Tennessee. We found that the plots represent a subset of the pollinator diversity at the landscape level at most of our sites but found no effect of land-use type of pollinator community homogenization. To complement this landscape survey, we also evaluated pollination services in a focal agricultural crop. First, we conducted a greenhouse study to evaluate biotic effects of tree health and pollen donor on fruit set. We found that tree identity and size affected the probability of fruit set in greenhouse cacao trees. Another way to evaluate the effect of management on agricultural pollination services is to measure fruit set in different management scenarios. For example, agroforestry is a more sustainable way to grow cacao (Theobroma cacao), an extremely important crop world-wide; however, the effects of agroforestry on cacao pollination are unknown. In addition, pollination may affect the varietal purity of cacao, thereby affecting its market value. We conducted a hand-pollination experiment on Criollo and Trinitario cacao grown within an agroforestry setting in Punta Gorda, Belize. We examined the self-pollination and cross-variety compatibility of these cacao varieties. We found that the Criollo variety can self-pollinate whereas the Trinitario variety cannot. However, both varieties are compatible with one another, leading to implications for pure heirloom chocolate production where they are grown in close proximity

Observations of the Optical Afterglow of GRB 050319 : Wind to ISM transition in view

The collapse of a massive star is believed to be the most probable progenitor of a long GRB. Such a star is expected to modify its environment by stellar wind. The effect of such a circum-stellar wind medium is expected to be seen in the evolution of a GRB afterglow, but has so far not been conclusively found. We claim that a signature of wind to constant density medium transition of circum-burst medium is visible in the afterglow of GRB 050319. Along with the optical observations of the afterglow of GRB 050319 we present a model for the multiband afterglow of GRB 050319. We show that the break seen in optical light curve at $\sim$ 0.02 day could be explained as being due to wind to constant density medium transition of circum-burst medium, in which case, to our knowledge, this could be the first ever detection of such a transition at any given frequency band. Detection of such a transition could also serve as a confirmation of massive star collapse scenario for GRB progenitors, independent of supernova signatures.Comment: 11 pages, 3 tables, 1 figure

Implications of the metallicity dependence of Wolf-Rayet winds

Aims: Recent theoretical predictions for the winds of Wolf-Rayet stars indicate that their mass-loss rates scale with the initial stellar metallicity in the local Universe.We aim to investigate how this predicted dependence affects the models of Wolf-Rayet stars and their progeny in different chemical environments. Methods: We compute models of stellar structure and evolution for Wolf-Rayet stars for different initial metallicities, and investigate how the scaling of the Wolf-Rayet mass-loss rates affects the final masses, the lifetimes of the WN and WC subtypes, and how the ratio of the two populations vary with metallicity. Results: We find significant effects of metallicity dependent mass-loss rates for Wolf-Rayet stars. For models that include the scaling of the mass-loss rate with initial metallicity, all WR stars become neutron stars rather than black holes at twice the solar metallicity; at lower $Z$, black holes have larger masses. We also show that our models that include the mass-loss metallicity scaling closely reproduce the observed decrease of the relative population of WC over WN stars at low metallicities.Comment: 8 pages, 9 figures, accepted by Astronomy & Astrophysic

The Night and Cultural Benefit : The Case for a Holistic Approach to Licensing

This research article critically engages with the Licensing Act (2003), arguing for a more holistic approach to licensing. Drawing on primary research conducted in London for the Greater London Authority (GLA), the article considers the positive benefits of licensed venues and the possibility of extending the licensing objectives to include their role in sustaining urban vitality. The current licensing objectives are steered towards minimising negative outcomes, with the assumption being that licensing is primarily a tool of control and minimising harm. The argument developed here is based on two alternative conceptions of the role of licensing. Firstly, licensing has a key role to play in developing sites for sociability and community cohesion. Though focused around alcohol, licensing is central to enabling or constraining more traditional as well as emerging spaces which combine entertainment, dining and other experimental forms of leisure. Second, the article argues that by addressing urban vitality and cultural benefit, the Act could be more attuned to the positive influence of licensed premises at a broader scale. The need for planning and licensing to work more cooperatively is considered in light of how licensing decisions reach beyond individual venues and impact on entire neighbourhoods or areas. Focusing on two London boroughs, Croydon and Lambeth, the paper examines how the current approach by local authorities to licensing could therefore be re-framed in more positive terms to acknowledge the wider cultural benefits and social good of licensed premises

On the nature of the progenitors of three type II-P supernovae: 2004et, 2006my and 2006ov

The pre-explosion observations of the type II-P supernovae 2006my, 2006ov and 2004et, are re-analysed. In the cases of supernovae 2006my and 2006ov we argue that the published candidate progenitors are not coincident with their respective supernova sites in pre-explosion Hubble Space Telescope observations. We therefore derive upper luminosity and mass limits for the unseen progenitors of both these supernovae, assuming they are red supergiants: 2006my (log L/Lsun = 4.51; mass < 13Msun) and 2006ov (log L/Lsun = 4.29; mass < 10Msun). In the case of supernova 2004et we show that the yellow-supergiant progenitor candidate, originally identified in Canada France Hawaii Telescope images, is still visible ~3 years post-explosion in observations from the William Herschel Telescope. High-resolution Hubble Space Telescope and Gemini (North) adaptive optics late-time imagery reveal that this source is not a single yellow supergiant star, but rather is resolved into at least three distinct sources. We report the discovery of the unresolved progenitor as an excess of flux in pre-explosion Isaac Newton Telescope i'-band imaging. Accounting for the late-time contribution of the supernova using published optical spectra, we calculate the progenitor photometry as the difference between the pre- and post-explosion, ground-based observations. We find the progenitor was most likely a late K to late M-type supergiant of 8 +5/-1 Msun. In all cases we conclude that future, high-resolution observations of the supernova sites will be required to confirm these results.Comment: 43 pages (pre-print format), 12 figures, 10 tables. Significant revision following referee's comments. Accepted for publication in MNRA

Coping with Persistent Pain, Effectiveness Research into Self-management (COPERS): statistical analysis plan for a randomised controlled trial

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated