Examining the effects of saccade execution and handedness on proactive interference.

Proactive interference is the phenomenon by which previously-learned information impairs recall of more recently-learned information. The present experiment was conducted to investigate two factors that may affect the occurrence of proactive interference. The first of these factors is saccade execution. Saccade execution has been shown in numerous studies to improve performance on a wide range of memory tasks. The second factor was people’s consistency of handedness, a term referring to the strength of people’s tendency to use one hand (right or left) over the other. Although the results of the primary analyses were inconclusive, further exploration of the data led to the proposition that saccades increase memory performance when no interference effect is induced, but may reduce performance when there is an interference effect. These results, although not significant in the expected way, still showed hints of interesting results

Spectrum and Wave Functions of Excited States in Lattice Gauge Theory

We suggest a new method to compute the spectrum and wave functions of excited states. We construct a stochastic basis of Bargmann link states, drawn from a physical probability density distribution and compute transition amplitudes between stochastic basis states. From such transition matrix we extract wave functions and the energy spectrum. We apply this method to $U(1)_{2+1}$ lattice gauge theory. As a test we compute the energy spectrum, wave functions and thermodynamical functions of the electric Hamiltonian and compare it with analytical results. We find excellent agreement. We observe scaling of energies and wave functions in the variable of time. We also present first results on a small lattice for the full Hamiltonian including the magnetic term.Comment: Lattice 2008 conferenc

Effects of motion on time perception

To investigate the effect of motion on time perception, participants were asked to perform either a temporal discrimination task or a temporal generalization task while running or standing still on a treadmill. In the temporal discrimination (bisection) task, 10 participants were exposed to two anchor stimuli, a 300-ms Short tone and a 700-ms Long tone, and then classified intermediate durations in terms of their similarity to the anchors. In the temporal generalization task, 10 other participants were exposed to a standard duration (500 ms) and then judged whether or not a series of comparison-durations, ranging from 300 ms to 700 ms, had the same duration as the standard. The results showed that in the temporal bisection task the participants produced more “Long” responses under the dual-task condition (temporal judgments + running) than under the single-task condition (temporal judgments only). In the temporal generalization task, accuracy in the temporal judgments was lower in the dual-task condition than the single-task condition. These results are discussed in the light of dual-task paradigm and of the Scalar Expectancy Theory (SET).Fundação para a Ciência e a Tecnologia (FCT

The application of passive sampler (DGT) technology for improved understanding of metal behaviour at a marine disposal site

Metal behaviour and availability at a contaminated dredge material disposal site within UK waters has been investigated using Diffusive Gradient in Thin films (DGT) passive sampling technology. Three stations representing contrasting history and presence of maintenance dredge disposal, including a control station outside the disposal site, have been studied and depth profiles of fluxes of different metals (Fe, Mn, Pb, Cu, Cd, Cr, Ni, Zn) to the binding gel (Chelex 100) have been derived. Higher flux rates and shallower mobilisation of metals (Mn and Fe) to the binding gel were observed at the disposal stations compared to the control station. Here we describe metal mobilization at different depths, linking the remobilization of Fe2+ and Mn2+ to the sediment (re)supply of other heavy metals of interest with a focus on Cd, Ni and Pb and as they are on the Water Framework Directive (WFD) list of priority substances and OSPAR list of priority pollutants. Results showed that Cd, Pb and Ni exhibited signs of resupply at the sediment-water interface (SWI). There was a potential increased mobilisation and source to the water column of Pb and Ni at the disposal site stations, but there was no Cd source, despite higher total loadings. This information has the potential to improve our current understanding of metal cycles at disposal sites. This work can be used as an indication of likely metal bioavailability and also assist in determining whether the sites act as sources or sinks of heavy metals. This information could assist disposal site monitoring and dredge material licensing

The agrin gene codes for a family of basal lamina proteins that differ in function and distribution

We isolated two cDNAs that encode isoforms of agrin, the basal lamina protein that mediates the motor neuron-induced aggregation of acetylcholine receptors on muscle fibers at the neuromuscular junction. Both proteins are the result of alternative splicing of the product of the agrin gene, but, unlike agrin, they are inactive in standard acetylcholine receptor aggregation assays. They lack one (agrin-related protein 1) or two (agrin-related protein 2) regions in agrin that are required for its activity. Expression studies provide evidence that both proteins are present in the nervous system and muscle and that, in muscle, myofibers and Schwann cells synthesize the agrin-related proteins while the axon terminals of motor neurons are the sole source of agrin

Single-chain polymer nanoparticles in controlled drug delivery and targeted imaging

As a relatively new class of materials, single-chain polymer nanoparticles (SCNPs) just entered the field of (biomedical) applications, with recent advances in polymer science enabling the formation of bio-inspired nanosized architectures. Exclusive intramolecular collapse of individual polymer chains results in individual nanoparticles. With sizes an order of magnitude smaller than conventional polymer nanoparticles, SCNPs are in the size regime of many proteins and viruses (1-20 nm). Multifaceted syntheses and design strategies give access to a wide set of highly modular SCNP materials. This review describes how SCNPs have been rendered water-soluble and highlights ongoing research efforts towards biocompatible SCNPs with tunable properties for controlled drug delivery, targeted imaging and protein mimicry

Thymic Dendritic Cell Subsets Display Distinct Efficiencies and Mechanisms of Intercellular MHC Transfer

Thymic dendritic cells (DC) delete self-Ag-specific thymocytes, and drive development of FoxP3-expressing immunoregulatory T cells. Unlike medullary thymic epithelial cells (mTEC), which express and present peripheral self-Ag, DC must acquire self-Ag to mediate thymic negative selection. One such mechanism entails the transfer of surface MHC-self peptide complexes from mTEC to thymic DC. Despite the importance of thymic DC “cross-dressing” in negative selection, the factors that regulate the process, and the capacity of different thymic DC subsets to acquire MHC and stimulate thymocytes are poorly understood. Here intercellular MHC transfer by thymic DC subsets was studied using a MHC-mismatch-based in vitro system. Thymic conventional DC (cDC) subsets SIRPα+ and CD8α+ readily acquired MHC class I and II from TEC but plasmacytoid DC (pDC) were less efficient. Intercellular MHC transfer was donor cell-specific; thymic DC readily acquired MHC from TEC plus thymic or splenic DC, whereas thymic or splenic B cells were poor donors. Furthermore DC origin influenced cross-dressing; thymic versus splenic DC exhibited an increased capacity to capture TEC-derived MHC, which correlated with direct expression of EpCAM by DC. Despite similar capacities to acquire MHC-peptide complexes, thymic CD8α+ cDC elicited increased T cell stimulation relative to SIRPα+ cDC. DC cross-dressing was cell-contact dependent and unaffected by lipid raft disruption of donor TEC. Furthermore, blocking PI3K signaling reduced MHC acquisition by thymic CD8α+ cDC and pDC but not SIRPα+ cDC. These findings demonstrate that multiple parameters influence the efficiency of and distinct mechanisms drive intercellular MHC transfer by thymic DC subsets

Food activities and identity maintenance in old age: a systematic review and meta-synthesis

This article has been made available through the Brunel Open Access Publishing Fund.Objectives: Services provided to older people should be developed based on active ageing policies. Nutrition is one aspect of active ageing, but little is known about how food activities contribute to psychological well-being in later life. This is a systematic review of qualitative and quantitative research that answers the question ‘What is known about the relationship between food activities and the maintenance of identities in old age?’

Transport and nonequilibrium phase transitions in polygonal urn models

We study the deterministic dynamics of N point particles moving at a constant speed in a 2D table made of two polygonal urns connected by an active rectangular channel, which applies a feedback control on the particles, inverting the horizontal component of their velocities when their number in the channel exceeds a fixed threshold. Such a bounce-back mechanism is non-dissipative: it preserves volumes in phase space. An additional passive channel closes the billiard table forming a circuit in which a stationary current may flow. Under specific constraints on the geometry and on the initial conditions, the large N limit allows nonequilibrium phase transitions between homogeneous and inhomogeneous phases. The role of ergodicity in making a probabilistic theory applicable is discussed for both rational and irrational urns. The theoretical predictions are compared with the numerical simulation results. Connections with the dynamics of feedback-controlled biological systems are highlighted