University of St Andrews

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.

The 2dF Galaxy Redshift Survey: galaxy luminosity functions per spectral type

Abstract: We calculate the optical bJ luminosity function of the 2dF Galaxy Redshift Survey (2dFGRS) for different subsets defined by their spectral properties. These spectrally selected subsets are defined using a new parameter, �, which is a linear combination of the first two projections derived from a Principal Component Analysis. This parameter � identifies the average emission and absorption line strength in the galaxy rest-frame spectrum and hence is a useful indicator of the present star formation. We use a total of 75,000 galaxies in our calculations, chosen from a sample of high signal-tonoise ratio, low redshift galaxies observed before January 2001. We find that there is a systematic steepening of the faint end slope (�) as one moves from passive (� = 0.54) to active (� = 1.50) star-forming galaxies, and that there is also a corresponding faintening of the rest-frame characteristic magnitude M � 5log10(h) (from 19.6 to 19.2). We also show that the Schechter function provides a poor fit to the quiescent (Type 1) LF for very faint galaxies (MbJ 5log10(h) fainter than 16.0), perhaps suggesting the presence of a significant dwarf population. The luminosity functions presented here give a precise confirmation of the trends seen previously in a much smaller preliminary 2dFGRS sample, and in other surveys. We also present a new procedure for determining self-consistent K-corrections and investigate possible fibreaperture biases.

Observation of the transfer of the local angular momentum density of a multiringed light beam to an optically trapped particle.

Abstract: We observe the spinning and orbital motion of a microscopic particle trapped within a multiringed light beam that arises from the transfer of the spin and orbital components of the light's angular momentum. The two rotation rates are measured as a function of the distance between the particle and the axis of the trapping beam. The radial dependence of these observations is found to be in close agreement with the accepted theory.

Large-scale magnetic topologies of early M dwarfs

Abstract: We present here additional results of a spectropolarimetric survey of a small sample of stars ranging from spectral type M0 to M8 aimed at investigating observationally how dynamo processes operate in stars on both sides of the full convection threshold (spectral type M4). The present paper focuses on early M stars (M0-M3), that is above the full convection threshold. Applying tomographic imaging techniques to time series of rotationally modulated circularly polarized profiles collected with the NARVAL spectropolarimeter, we determine the rotation period and reconstruct the large-scale magnetic topologies of six early M dwarfs. We find that early-M stars preferentially host large-scale fields with dominantly toroidal and non-axisymmetric poloidal configurations, along with significant differential rotation (and long-term variability); only the lowest-mass star of our subsample is found to host an almost fully poloidal, mainly axisymmetric large-scale field resembling those found in mid-M dwarfs. This abrupt change in the large-scale magnetic topologies of M dwarfs (occurring at spectral type M3) has no related signature on X-ray luminosities (measuring the total amount of magnetic flux); it thus suggests that underlying dynamo processes become more efficient at producing large-scale fields (despite producing the same flux) at spectral types later than M3. We suspect that this change relates to the rapid decrease in the radiative cores of low-mass stars and to the simultaneous sharp increase of the convective turnover times (with decreasing stellar mass) that models predict to occur at M3; it may also be (at least partly) responsible for the reduced magnetic braking reported for fully convective stars. Based on observations obtained at the Telescope Bernard Lyot (TBL), operated by the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique of France. E-mail: donati@ast.obs-mip.fr (J-FD); jmorin@ast.obs-mip.fr (JM); petit@ast.obs-mip.fr (PP); xavier.delfosse@obs.ujf-grenoble.fr (XD); thierry.forveille@obs.ujf-grenoble.fr (TF); auriere@ast.obs-mip.fr (MA); remi.cabanac@ast.obs-mip.fr (RC); dintrans@ast.obs-mip.fr (BD); rfares@ast.obs-mip.fr (RF); tgastine@ast.obs-mip.fr (TG); mmj@st-and.ac.uk (MMJ); lignieres@ast.obs-mip.fr (FL); fpaletou@ast.obs-mip.fr (FP); julio.ramirez@obspm.fr (JCRV); sylvie.theado@ast.obs-mip.fr (ST)

Accounting and sustainable development: An exploration

Abstract: As the social and environmental impacts of human activity have become more evident, the role of sustainable development as an organising principle in a variety of policy contexts and over multiple scales has become central There are, at least, two implications that emerge from this observation First, morally infused problems that need to be addressed have become more intractable, requiring innovation in our modes of thinking Second, new spaces have emerged where the academy might explore how knowledge is created, validated and translated (or not) alongside policy and practice settings One outcome of these trends has been the emergence of a stream of work (sustainability science) which investigates how disciplines might develop knowledge that progresses sustainable development The aim of this paper, in line with the focus of the special issue, is to explore what possibilities emerge for accounting in light of a sustainability science approach To achieve this end the paper starts with an exploration of the frustrations expressed in the literature over the perceived lack of progress made by social and environmental accounting towards addressing sustainable development The paper then introduces sustainability science with the aim of imagining how an accounting for sustainable development might emerge The paper closes with two illustrations of how a sustainability science approach to accounting could develop

Improving occupancy estimation when two types of observational error occur: non‐detection and species misidentification

Abstract: Efforts to draw inferences about species occurrence frequently account for false negatives, the common situation when individuals of a species are not detected even when a site is occupied. However, recent studies suggest the need to also deal with false positives, which occur when species are misidentified so that a species is recorded as detected when a site is unoccupied. Bias in estimators of occupancy, colonization, and extinction can be severe when false positives occur. Accordingly, we propose models that simultaneously account for both types of error. Our approach can be used to improve estimates of occupancy for study designs where a subset of detections is of a type or method for which false positives can be assumed to not occur. We illustrate properties of the estimators with simulations and data for three species of frogs. We show that models that account for possible misidentification have greater support (lower AIC for two species) and can yield substantially different occupancy estimates than those that do not. When the potential for misidentification exists, researchers should consider analytical techniques that can account for this source of error, such as those presented here.