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Institution

University of St Andrews

EducationSt Andrews, Fife, United Kingdom
About: University of St Andrews is a education organization based out in St Andrews, Fife, United Kingdom. It is known for research contribution in the topics: Population & Laser. The organization has 16260 authors who have published 43364 publications receiving 1636072 citations. The organization is also known as: St Andrews University & University of St. Andrews.
Topics: Population, Laser, Planet, Galaxy, Stars


Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors use numerical simulations to constrain the hardware design and observing strategy for the SDSS-IV mapping program with the aim of ensuring consistent data quality that meets the survey science requirements while permitting maximum observational flexibility.
Abstract: Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) is an integral-field spectroscopic survey that is one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV). MaNGA's 17 pluggable optical fiber-bundle integral field units (IFUs) will observe a sample of 10,000 nearby galaxies distributed throughout the SDSS imaging footprint (focusing particularly on the North Galactic Cap). In each pointing these IFUs are deployed across a 3° field; they yield spectral coverage 3600−10300 A at a typical resolution R ~ 2000, and sample the sky with 2'' diameter fiber apertures with a total bundle fill factor of 56%. Observing over such a large field and range of wavelengths is particularly challenging for obtaining uniform and integral spatial coverage and resolution at all wavelengths and across each entire fiber array. Data quality is affected by the IFU construction technique, chromatic and field differential refraction, the adopted dithering strategy, and many other effects. We use numerical simulations to constrain the hardware design and observing strategy for the survey with the aim of ensuring consistent data quality that meets the survey science requirements while permitting maximum observational flexibility. We find that MaNGA science goals are best achieved with IFUs composed of a regular hexagonal grid of optical fibers with rms displacement of 5 μm or less from their nominal packing position; this goal is met by the MaNGA hardware, which achieves 3 μm rms fiber placement. We further show that MaNGA observations are best obtained in sets of three 15 minute exposures dithered along the vertices of a 1.44 arcsec equilateral triangle; these sets form the minimum observational unit, and are repeated as needed to achieve a combined signal-to-noise ratio of 5 A-1 per fiber in the r-band continuum at a surface brightness of 23 AB arcsec-2. In order to ensure uniform coverage and delivered image quality, we require that the exposures in a given set be obtained within a 60 minute interval of each other in hour angle, and that all exposures be obtained at airmass ≲ 1.2 (i.e., within 1–3 hr of transit depending on the declination of a given field).

305 citations

Journal ArticleDOI
TL;DR: NKT cells are best known for their immunosuppressive functions; however, NKT cells interact with a range of other cell types and the outcome of NKT-cell stimulation depends on these and on the cytokine/co-stimulatory milieu.

304 citations

Journal ArticleDOI
01 Oct 2007-The Auk
TL;DR: Thomas et al. as mentioned in this paper presented methods that allow us to model probability of detection as a function of additional covariates, allowing us to increase the reliability of density estimates made on subsets of the whole data (e.g., estimates for different habitats, treatments, periods or species).
Abstract: Inferences based on counts adjusted for detectability represent a marked improvement over unadjusted counts, which provide no information about true population density and rely on untestable and unrealistic assumptions about constant detectability for inferring differences in density over time or space. Distance sampling is a widely used method to estimate detectability and therefore density. In the standard method, we model the probability of detecting a bird as a function of distance alone. Here, we describe methods that allow us to model probability of detection as a function of additional covariates—an approach available in DISTANCE, version 5.0 (Thomas et al. 2005) but still not widely applied. The main use of these methods is to increase the reliability of density estimates made on subsets of the whole data (e.g., estimates for different habitats, treatments, periods, or species), to increase precision of density estimates or to allow inferences about the covariates themselves. We present a...

304 citations

Journal ArticleDOI
TL;DR: It is concluded that hippocampal lesions severely but partially impair spatial but not visual reference memory and give rise to different patterns impairment in different working-mermory tasks.
Abstract: This paper reports a series of three experiments that tested the “spatial-mapping” and “working-memory” theories of hippocampal function. The experimental designs incorporate separate reference- an...

304 citations

Journal ArticleDOI
TL;DR: This article presented a modified surface energy-balance model to calculate melt beneath a surface debris layer from daily mean meteorological variables, showing that the model performs well and modelled melt rates give a good match to observed melt rates.
Abstract: Generalized numerical models of sub-debris ice ablation are preferable to empirical approaches for predicting runoff and glacier response to climate change, as empirical methods are site-specific and strongly dependent upon the conditions prevailing during the measurement period. We present a modified surface energy-balance model to calculate melt beneath a surface debris layer from daily mean meteorological variables. Despite numerous simplifications, the model performs well and modelled melt rates give a good match to observed melt rates, suggesting that this model can produce reliable estimates of ablation rate beneath debris layers several decimetres thick. This is a useful improvement on previous models which are inappropriate for thick debris cover.

303 citations


Authors

Showing all 16531 results

NameH-indexPapersCitations
Yi Chen2174342293080
Paul M. Thompson1832271146736
Ian J. Deary1661795114161
Dongyuan Zhao160872106451
Mark J. Smyth15371388783
Harry Campbell150897115457
William J. Sutherland14896694423
Thomas J. Smith1401775113919
John A. Peacock140565125416
Jean-Marie Tarascon136853137673
David A. Jackson136109568352
Ian Ford13467885769
Timothy J. Mitchison13340466418
Will J. Percival12947387752
David P. Lane12956890787
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023127
2022387
20211,998
20201,996
20192,059
20181,946