Rotational response of two-component Bose-Einstein condensates in ring traps

We consider a two-component Bose-Einstein condensate in a ring trap in a rotating frame and show how to determine the response of such a configuration to being in a rotating frame via accumulation of a Sagnac phase. This may be accomplished through either population oscillations or the motion of spatial-density fringes. We explicitly include the effect of interactions via a mean-field description and study the fidelity of the dynamics relative to an ideal configuration

Cue Competition in Human Incidental Learning

McLaren, I. P., Jones, F. W., McLaren, R. and Yeates, F. (2013) Cue competition in human incidental learning. In: Reinforcement Learning and Decision Making Meeting 2013, 25th-27th October, Princeton, New Jersey, USA .There is a question as to whether cue competition effects can be observed in incidental learning paradigms in humans. Some authors have reported that cue competition is not observed, and that previous demonstrations of cue competition have relied on explicit awareness of the task in hand. This would imply that these effects are more likely to be the product of cognitive inference than associative learning. We addressed this question by using two paradigms previously shown to produce associative learning under incidental conditions. One was a standard SRT task in which the preceding two trials of a run of three predicted the third 2/3 of the time, and the other was based on another predictive cue, a colored square, which could also stochastically predict the next response required.We have demonstrated in other studies that both cues would support learning under incidental conditions in the absence of any verbalisable knowledge of the rules involved. The question was to what extent would these two cues compete if run concurrently, as assayed by their ability to make the next response faster and more accurate than controls? We assessed this by comparing a dual cue group to a color only control and a sequence only control. Our results showed that all three groups learned, but that during a test phase where each cue could be assessed independently, the dual group showed a marked decline in performance relative to the color control, and very similar performance to the sequence control. We interpret this as evidence for overshadowing occurring between the two predictive cues in the dual group, such that when combined their performance would be equivalent or superior to either control, but when assessed independently, the color cue actually has a weaker association to the outcome than the equivalent cue in the control group. We conclude that the sequence cues overshadowed the color cues in this task, and discuss possible theoretical accounts of this phenomenon

Chapter 12: Vulnerability of fishes of the Great Barrier Reef to climate change

Climate change has already caused significant impacts to Earth’s ecosystems. Shifts in plant and animal biogeographic ranges, changes to population abundance, adjustments in the timing of seasonal activities and the establishment of invasive species have all been attributed to climate change. Most examples of biological impacts from climate change involve terrestrial species, however, similar effects have been observed in marine species, especially from temperate regions. The impact of climate change on coral reefs has also been widely considered, mostly with regard to coral bleaching and the degradation of coral communities. Much less attention has been given to the impact that climate change will have on other organisms that are associated with coral reefs. Fish are one of the most conspicuous and diverse components of tropical marine ecosystems, yet how they will be affected by climate change has not been comprehensively assessed.This is Chapter 12 of Climate change and the Great Barrier Reef: a vulnerability assessment. The entire book can be found at http://hdl.handle.net/11017/13

Competition between plant and bacterial cells at the microscale regulates the dynamics of nitrogen acquisition in wheat (Triticum aestivum)

The ability of plants to compete effectively for nitrogen (N) resources is critical to plant survival. However, controversy surrounds the importance of organic and inorganic sources of N in plant nutrition because of our poor ability to visualize and understand processes happening at the root�microbial�soil interface. Using high-resolution nano-scale secondary ion mass spectrometry stable isotope imaging (NanoSIMS-SII), we quantified the fate of 15N over both space and time within the rhizosphere. We pulse-labelled the soil surrounding wheat (Triticum aestivum) roots with either inline image or 15N-glutamate and traced the movement of 15N over 24 h. Imaging revealed that glutamate was rapidly depleted from the rhizosphere and that most 15N was captured by rhizobacteria, leading to very high 15N microbial enrichment. After microbial capture, approximately half of the 15N-glutamate was rapidly mineralized, leading to the excretion of inline image, which became available for plant capture. Roots proved to be poor competitors for 15N-glutamate and took up N mainly as inline image. Spatial mapping of 15N revealed differential patterns of 15N uptake within bacteria and the rapid uptake and redistribution of 15N within roots. In conclusion, we demonstrate the rapid cycling and transformation of N at the soil�root interface and that wheat capture of organic N is low in comparison to inorganic N under the conditions tested

Not all phylogenetic networks are leaf-reconstructible

Unrooted phylogenetic networks are graphs used to represent reticulate evolutionary relationships. Accura

Implicit Learning: A Demonstration and a Revision of a Novel SRT Paradigm.

CogSci 2013 - 35th annual meeting of the Cognitive Science Society, Berlin, Germany, 31 July - 3 August 2013Yeates, Jones, Wills, Aitken, McLaren and McLaren (2012)devised a serial reaction time (SRT) task that provided evidence for human learning without awareness. Adapting the SRT paradigm usually employed to investigate implicit learning, participants responded to two simple white circle fills on either side of a screen. Instead of these following a sequence that participants were unaware of (e.g. Willingham, Nissen & Bullemer, 1989) this task involved a separate stimulus, which was sometimes predictive of one of the circle fills. A square in the center of the screen would fill with one of eight colors before each circle fill: one of these colors predicted a right circle fill and the other a left on 80% of trials on which those colors occurred. When pressing the key that followed the consistent response trained with these two colors, participants were both faster and more accurate than when responding to either the inconsistent response or control colors. Participants demonstrated a lack of contingency awareness, performing at chance in identifying the predictive colors and on a suitably sensitive prediction task. On reanalyzing this result, this paper shows that it was confounded with a sequential artifact produced by the experimental design itself. Pilot studies demonstrated weak learning of color contingencies when the artifact was removed, thus we sought to improve learning by both increasing the amount of training and placing the predictive color cue on the circle fills. Without the sequential artifact, we can produce the same result, although we concede the effect is less robust than we first indicated. Thus, we are able to reiterate our original conclusion: that this task can demonstrate learning of color contingencies in the absence of awareness and can be used to investigate implicit learning in humans

Implicit Learning: A Demonstration and a Novel SRT Paradigm

CogSci 2012 - 34th annual meeting of the Cognitive Science Society, Sapporo, Japan, 1-4 August 2012Evidence for human learning without awareness of what is learned has been sought in serial reaction time (SRT) tasks in which, unknown to participants, the locations of stimuli follow a particular rule or sequence (Willingham, Nissen & Bullemer, 1989). A number of criticisms have been levelled at such tasks, including a lack of adequate control for sequential effects and a discrepancy in sensitivity between measures of implicit and explicit knowledge about the task (Jones & McLaren, 2009; Shanks & St. John, 1994). In this study we provide a novel, two-choice SRT paradigm whereby the locations of the response stimuli are sometimes predicted by a separate set of stimuli on screen. A color-filled square appears before each stimulus requiring a response, with participants informed this is simply a fixation point to prepare for the next trial. Two out of eight colors are predictive on 80% of trials, and performance on these consistent trials was faster than on the other six colors that were equally likely to result in either of the two possible responses. All these trial types were faster and more accurate than the remaining inconsistent 20% of trials for the predictive colors, which also produce more errors than control colors. A prediction task and interview followed the task, on which participants performed at near (slightly below) chance levels. We suggest that this task is a useful tool for studying associative learning in humans, as it provides reliable effects that appear to demonstrate implicit learning with relatively brief training.This research was supported by an ESRC grant to IPL McLaren and FW Jone

Classical integrable lattice models through quantum group related formalism

We translate effectively our earlier quantum constructions to the classical language and using Yang-Baxterisation of the Faddeev-Reshetikhin-Takhtajan algebra are able to construct Lax operators and associated $r$-matrices of classical integrable models. Thus new as well as known lattice systems of different classes are generated including new types of collective integrable models and canonical models with nonstandard $r$ matrices.Comment: 7 pages; Talk presented at NEEDS'93 (Gallipoli,Italy

Environmental baseline monitoring - Vale of Pickering: Phase I - final report (2015/16)

This report presents the collated results from the BGS-led project Science-based environmental baseline monitoring associated with shale gas development in the Vale of Pickering (including supplementary air quality monitoring in Lancashire). The project has been funded by a grant awarded by DECC for the period August 2015 – 31st March 2016. It complements (and extends to air quality) an on-going project, funded by BGS and the other project partners, in which similar activities are being carried out in the Fylde area of Lancashire. The project has initiated a wide-ranging environmental baseline monitoring programme that includes water quality (groundwater and surface water), seismicity, ground motion, atmospheric composition (greenhouse gases and air quality), soil gas and radon in air (indoors and outdoors). The motivation behind the project(s) was to establish independent monitoring in the area around the proposed shale gas hydraulic fracturing sites in the Vale of Pickering, North Yorkshire (Third Energy) and in Lancashire (Cuadrilla) before any shale gas operations take place. As part of the project, instrumentation has been deployed to measure, in real-time or near real-time, a range of environmental variables (water quality, seismicity, atmospheric composition). These data are being displayed on the project’s web site (www.bgs.ac.uk/Valeofpickering). Additional survey, sampling and monitoring has also been carried out through a co-ordinated programme of fieldwork and laboratory analysis, which has included installation of new monitoring infrastructure, to allow compilation of one of the most comprehensive environmental datasets in the UK. It is generally recognised that at least 12 months of baseline data are required. The duration of the grant award (7 months) has meant that this has not yet been possible. However there are already some very important findings emerging from the limited datasets which need be taken in to account when developing future monitoring strategy, policy and regulation. The information is not only relevant to the Vale of Pickering and Lancashire but will be more widely applicable in the UK and internationally. Although shale gas operations in other parts of the world are well-established there is a paucity of good baseline data and effective guidance on monitoring. It is hoped that the monitoring project will continue to allow at least 12 months of data for each of the work packages to be compiled and analysed. It will also allow the experience gained and the scientifically-robust findings to be used to develop and establish effective environmental monitoring strategies for shale gas and similar industrial activities

Shapes of the Proton

A model proton wave function, constructed using Poincare invariance, and constrained by recent electromagnetic form factor data, is used to study the shape of the proton. Spin-dependent quark densities are defined as matrix elements of density operators in proton states of definite spin-polarization, and shown to have an infinite variety of non-spherical shapes. For high momentum quarks with spin parallel to that of the proton, the shape resembles that of a peanut, but for quarks with anti-parallel spin the shape is that of a bagel.Comment: 8 pages, 5 figures, to be submitted to Phys. Rev. C This corrects a few typos and explains some further connections with experiment