Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

Article Types

Countries / Regions

Search Results (3)

Search Parameters:
Authors = D. John Hillier

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
27 pages, 3766 KiB  
Review
Photoionization and Electron–Ion Recombination in Astrophysical Plasmas
by D. John Hillier
Atoms 2023, 11(3), 54; https://doi.org/10.3390/atoms11030054 - 9 Mar 2023
Cited by 6 | Viewed by 3013
Abstract
Photoionization and its inverse, electron–ion recombination, are key processes that influence many astrophysical plasmas (and gasses), and the diagnostics that we use to analyze the plasmas. In this review we provide a brief overview of the importance of photoionization and recombination in astrophysics. [...] Read more.
Photoionization and its inverse, electron–ion recombination, are key processes that influence many astrophysical plasmas (and gasses), and the diagnostics that we use to analyze the plasmas. In this review we provide a brief overview of the importance of photoionization and recombination in astrophysics. We highlight how the data needed for spectral analyses, and the required accuracy, varies considerably in different astrophysical environments. We then discuss photoionization processes, highlighting resonances in their cross-sections. Next we discuss radiative recombination, and low and high temperature dielectronic recombination. The possible suppression of low temperature dielectronic recombination (LTDR) and high temperature dielectronic recombination (HTDR) due to the radiation field and high densities is discussed. Finally we discuss a few astrophysical examples to highlight photoionization and recombination processes. Full article
(This article belongs to the Special Issue Photoionization of Atoms)
Show Figures

Figure 1

29 pages, 3592 KiB  
Review
UV Spectroscopy of Massive Stars
by D. John Hillier
Galaxies 2020, 8(3), 60; https://doi.org/10.3390/galaxies8030060 - 12 Aug 2020
Cited by 23 | Viewed by 7216
Abstract
We present a review of UV observations of massive stars and their analysis. We discuss O stars, luminous blue variables, and Wolf–Rayet stars. Because of their effective temperature, the UV (9123200 Å) provides invaluable diagnostics not available at other wavebands. [...] Read more.
We present a review of UV observations of massive stars and their analysis. We discuss O stars, luminous blue variables, and Wolf–Rayet stars. Because of their effective temperature, the UV (9123200 Å) provides invaluable diagnostics not available at other wavebands. Enormous progress has been made in interpreting and analysing UV data, but much work remains. To facilitate the review, we provide a brief discussion on the structure of stellar winds, and on the different techniques used to model and interpret UV spectra. We discuss several important results that have arisen from UV studies including weak-wind stars and the importance of clumping and porosity. We also discuss errors in determining wind terminal velocities and mass-loss rates. Full article
(This article belongs to the Special Issue Star Formation in the Ultraviolet)
Show Figures

Figure 1

21 pages, 195 KiB  
Article
What Do We Need to Know to Enhance the Environmental Sustainability of Agricultural Production? A Prioritisation of Knowledge Needs for the UK Food System
by Lynn V. Dicks, Richard D. Bardgett, Jenny Bell, Tim G. Benton, Angela Booth, Jan Bouwman, Chris Brown, Ann Bruce, Paul J. Burgess, Simon J. Butler, Ian Crute, Frances Dixon, Caroline Drummond, Robert P. Freckleton, Maggie Gill, Andrea Graham, Rosie S. Hails, James Hallett, Beth Hart, Jon G. Hillier, John M. Holland, Jonathan N. Huxley, John S. I. Ingram, Vanessa King, Tom MacMillan, Daniel F. McGonigle, Carmel McQuaid, Tim Nevard, Steve Norman, Ken Norris, Catherine Pazderka, Inder Poonaji, Claire H. Quinn, Stephen J. Ramsden, Duncan Sinclair, Gavin M. Siriwardena, Juliet A. Vickery, Andrew P. Whitmore, William Wolmer and William J. Sutherlandadd Show full author list remove Hide full author list
Sustainability 2013, 5(7), 3095-3115; https://doi.org/10.3390/su5073095 - 17 Jul 2013
Cited by 38 | Viewed by 20889
Abstract
Increasing concerns about global environmental change and food security have focused attention on the need for environmentally sustainable agriculture. This is agriculture that makes efficient use of natural resources and does not degrade the environmental systems that underpin it, or deplete natural capital [...] Read more.
Increasing concerns about global environmental change and food security have focused attention on the need for environmentally sustainable agriculture. This is agriculture that makes efficient use of natural resources and does not degrade the environmental systems that underpin it, or deplete natural capital stocks. We convened a group of 29 ‘practitioners’ and 17 environmental scientists with direct involvement or expertise in the environmental sustainability of agriculture. The practitioners included representatives from UK industry, non-government organizations and government agencies. We collaboratively developed a long list of 264 knowledge needs to help enhance the environmental sustainability of agriculture within the UK or for the UK market. We refined and selected the most important knowledge needs through a three-stage process of voting, discussion and scoring. Scientists and practitioners identified similar priorities. We present the 26 highest priority knowledge needs. Many of them demand integration of knowledge from different disciplines to inform policy and practice. The top five are about sustainability of livestock feed, trade-offs between ecosystem services at farm or landscape scale, phosphorus recycling and metrics to measure sustainability. The outcomes will be used to guide on-going knowledge exchange work, future science policy and funding. Full article
(This article belongs to the Special Issue Sustainable Food Chains)
Show Figures

Figure 1

Back to TopTop