Survival of the Fittest: Increased Stimulus Competition During Encoding Results in Fewer but More Robust Memory Traces

Forgetting can be accounted for by time-indexed decay as well as competition-based interference processes. Although conventionally seen as competing theories of forgetting processes, Altmann and colleagues argued for a functional interaction between decay and interference. They revealed that, in short-term memory, time-based forgetting occurred at a faster rate under conditions of high proactive interference compared to conditions of low proactive interference. However, it is unknown whether interactive effects between decay-based forgetting and interference-based forgetting also exist in long-term memory. We employed a delayed memory recognition paradigm for visual indoor and outdoor scenes, measuring recognition accuracy at two time-points, immediately after learning and after 1 week, while interference was indexed by the number of images in a semantic category. We found that higher levels of interference during encoding led to a slower subsequent decay rate. In contrast to the findings in working-memory, our results suggest that a "survival of the fittest" principle applies to long-term memory processes, in which stimulus competition during encoding results in fewer, but also more robust memory traces, which decay at a slower rate. Conversely, low levels of interference during encoding allow more memory traces to form initially, which, however, subsequently decay at a faster rate. Our findings provide new insights into the mechanism of forgetting and could inform neurobiological models of forgetting

Island Making: Planning artistic collaboration

A knowledge exchange programme exploring the role of art in relation to the planning context of the Holy Island of Lindisfarne, this paper explores the role of artistic knowledge in making landscape. During 2013, 25 artistic workshops were developed in collaboration with residents and planning officials, resulting in an exhibition of works produced. From a pragmatist perspective this paper draws on ethnographic accounts of the realisation of the exhibition to reveal artistic knowledge exchange as ‘relational knowing’. The contribution of the paper is to recommend we account for artistic work as an ingredient of landscape planning. Although specifically drawing on fieldwork in Holy Island the experiential nature of this article makes a novel contribution across the field of rural planning

Micro-computed tomography pore-scale study of flow in porous media: Effect of voxel resolution

A fundamental understanding of flow in porous media at the pore-scale is necessary to be able to upscale average displacement processes from core to reservoir scale. The study of fluid flow in porous media at the pore-scale consists of two key procedures: Imaging - reconstruction of three-dimensional (3D) pore space images; and modelling such as with single and two-phase flow simulations with Lattice-Boltzmann (LB) or Pore-Network (PN) Modelling. Here we analyse pore-scale results to predict petrophysical properties such as porosity, single-phase permeability and multi-phase properties at different length scales. The fundamental issue is to understand the image resolution dependency of transport properties, in order to up-scale the flow physics from pore to core scale. In this work, we use a high resolution micro-computed tomography (micro-CT) scanner to image and reconstruct three dimensional pore-scale images of five sandstones (Bentheimer, Berea, Clashach, Doddington and Stainton) and five complex carbonates (Ketton, Estaillades, Middle Eastern sample 3, Middle Eastern sample 5 and Indiana Limestone 1) at four different voxel resolutions (4.4 µm, 6.2 µm, 8.3 µm and 10.2 µm), scanning the same physical field of view. Implementing three phase segmentation (macro-pore phase, intermediate phase and grain phase) on pore-scale images helps to understand the importance of connected macro-porosity in the fluid flow for the samples studied. We then compute the petrophysical properties for all the samples using PN and LB simulations in order to study the influence of voxel resolution on petrophysical properties. We then introduce a numerical coarsening scheme which is used to coarsen a high voxel resolution image (4.4 µm) to lower resolutions (6.2 µm, 8.3 µm and 10.2 µm) and study the impact of coarsening data on macroscopic and multi-phase properties. Numerical coarsening of high resolution data is found to be superior to using a lower resolution scan because it avoids the problem of partial volume effects and reduces the scaling effect by preserving the pore-space properties influencing the transport properties. This is evidently compared in this study by predicting several pore network properties such as number of pores and throats, average pore and throat radius and coordination number for both scan based analysis and numerical coarsened data

Does protest really work in cosy democracies?

Does protest work? And is it more effective when it takes places in countries ruled by repressive regimes or those with democratically elected governments? Steve Crawshaw writes that if we think nothing will change, as people often do in democracies, that lack of belief becomes self-fulfilling

Getting to know the island: Artistic experiments in rural community development

This paper makes an original contribution to our understandings of the relational role of artistic practice as part of rural community development. Art-led initiatives are now commonplace in rural development strategies. However, the effects of art in rural community, particularly beyond economic development, have received little attention. In this paper we seek to address this omission by exploring artistic ex- periments as part of community development processes. Theoretically, we draw on relational un- derstandings of art from art studies. Empirically, the paper utilises data collected through a one-year experimental study involving ethnography and artistic interventions in the community of the Holy Island of Lindisfarne in the north east of England. By directing our consideration of art via Liepins' framework (2000a) for ‘reading’ the community, we reveal artistic practice itself as a way to ‘read relationships’. Rather than a tool for solving community problems, we conceptualise artistic practice as a ‘diagnostic’. © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY licens

Full report of the evaluation of the Liberia PRRO 10454.0 (July 2007-June 2009): a report from the Office of Evaluation

This evaluation examined the relevance, efficiency, effectiveness, impact and sustainability of protracted relief and recovery operation 10454.0 “Food Assistance for Relief and Recovery in Post-Conflict Liberia”. The objective of the evaluation was twofold: i) to determine the degree to which project objectives had been achieved; and ii) to draw lessons from which to enhance performance in the next phase of the operation. The evaluation was carried out by a team of external consultants who conducted field research from 2 to 19 November 2008. The evaluation found that there was a clear need for food aid in Liberia and that school feeding, which accounted for approximately three quarters of project commodities, was an appropriate activity that channelled substantial quantities of food to remote rural areas under difficult operational conditions. However, the evaluation also found that the operation design was weak: it sought to achieve too much in a situation where capacity to implement programmes was extremely limited at all levels, and the main activities did little to address the main causes of food insecurity and vulnerability in the country. The operation design could have been more closely linked to the findings of the 2006 comprehensive food security and nutrition survey, and could have considered transition issues and exit strategies more fully. The operation became measurably more efficient during the period under review, owing to a series of management initiatives that resulted in better accountability at all levels and lower operational costs. However, although service delivery improved, monthly delivery targets were rarely met, and project outputs were generally below planned levels, owing to poor rural transport infrastructure and severe damage caused by rainy seasons. It was difficult to assess the operation’s effectiveness, because an adequate monitoring and evaluation system was not in place, but the evaluation found that the impact was generally positive and significant. There was widespread agreement that the school feeding activity had been important in helping to: i) revitalize the education system in rural areas; and ii) encourage the return and resettlement of displaced people. Many participants in food for work had invested a portion of their wages in income-generation ventures, which had led to sustained increases in household income. WFP’s capacity-building efforts had helped to bring food security and nutrition issues to the forefront of policy discussion in Liberia. Future interventions should seek to address the causes of food insecurity and vulnerability directly. Interventions should be more clearly focused, to bring them into line with prevailing implementation capacities, and should address issues of transition and the phase-out of activities. Protracted relief and recovery operation and school feeding guidance should identify more clearly the different types of transition and appropriate indicators to guide the timing of the transition process. Nutrition activities should be refocused to address chronic malnutrition through an expanded mother-and-child health programme

Deposition of colloidal asphaltene in capillary flow: Experiments and mesoscopic simulations

The aggregation and deposition of colloidal asphaltene in reservoir rock is a significant problem in the oil industry. To obtain a fundamental understanding of this phenomenon, we have studied the deposition and aggregation of colloidal asphaltene in capillary flow by experiment and simulation. For the simulation, we have used the stochastic rotation dynamics (SRD) method, in which the solvent hydrodynamic emerges from the collisions between the solvent particles, while the Brownian motion emerges naturally from the interactions between the colloidal asphaltene particles and the solvent. The asphaltene colloids interact through a screened Coulomb potential. We vary the well depth ecc and the flow rate v to obtain Peflow » 1 (hydrodynamic interactions dominate) and Re « 1 (Stokes flow). In the simulations, we impose a pressure drop over the capillary length and measure the corresponding solvent flow rate. We observe that the transient solvent flow rate decreases when the asphaltene particles become more sticky . For a well depth ecc = 2kBT, a monolayer deposits on the capillary wall. With an increasing well depth, the capillary becomes totally blocked. The clogging is transient for ecc = 5kBT, but appears to be permanent for ecc = 10-20kBT. We compare our simulation results with flow experiments in glass capillaries, where we use extracted asphaltenes in toluene, reprecipitated with n-heptane. In the experiments, the dynamics of asphaltene precipitation and deposition were monitored in a slot capillary using optical microscopy under flow conditions similar to those used in the simulation. Maintaining a constant flow rate of 5 µL min-1, we found that the pressure drop across the capillary first increased slowly, followed by a sharp increase, corresponding to a complete local blockage of the capillary. Doubling the flow rate to 10 µL min-1, we observe that the initial deposition occurs faster but the deposits are subsequently entrained by the flow. We calculate the change in the dimensionless permeability as a function of time for both experiment and simulation. By matching the experimental and simulation results, we obtain information about (1) the interaction potential well depth for the particular asphaltenes used in the experiments and (2) the flow conditions associated with the asphaltene deposition process. © 2008 American Chemical Society