Simulating Cortical Feedback Modulation as Changes in Excitation and Inhibition in a Cortical Circuit Model.

Cortical feedback pathways are hypothesized to distribute context-dependent signals during flexible behavior. Recent experimental work has attempted to understand the mechanisms by which cortical feedback inputs modulate their target regions. Within the mouse whisker sensorimotor system, cortical feedback stimulation modulates spontaneous activity and sensory responsiveness, leading to enhanced sensory representations. However, the cellular mechanisms underlying these effects are currently unknown. In this study we use a simplified neural circuit model, which includes two recurrent excitatory populations and global inhibition, to simulate cortical modulation. First, we demonstrate how changes in the strengths of excitation and inhibition alter the input-output processing responses of our model. Second, we compare these responses with experimental findings from cortical feedback stimulation. Our analyses predict that enhanced inhibition underlies the changes in spontaneous and sensory evoked activity observed experimentally. More generally, these analyses provide a framework for relating cellular and synaptic properties to emergent circuit function and dynamic modulation

Strategic adoption of logistics and supply chain management

© 2018, Emerald Publishing Limited. Purpose: The purpose of this paper is to develop a thorough understanding of the adoption of logistics and supply chain management (SCM) in practice, particularly at a strategic level, through an investigation of the four perspectives taxonomy of the relationship between logistics and SCM. Design/methodology/approach: Based on a comprehensive literature review, three specific research questions are proposed. The empirical work addresses these questions and comprised three phases: focussed interviews, a questionnaire survey and focus groups. Findings: The findings provide a usage profile of the four perspectives and indicate a divergence between the understanding and adoption of logistics and SCM principles and concepts at a strategic level in firms. The findings also identify the critical success factors (CSFs) and inhibitors to success in addressing this divergence. Research limitations/implications: The insights generated using the authors’ methodologically pluralist research design could be built upon to include case studies, grounded theory and action research. Replicating the research in other geographical areas could facilitate international comparisons. Practical implications: The findings allow practitioners to compare their perspectives on the relationship between logistics and SCM with those of their peers. The CSFs and inhibitors to success provide a rational basis for realising the strategic potential of logistics and SCM in practice. Originality/value: New insights are generated into practitioner perspectives vis-à-vis logistics vs SCM. A fresh understanding of those factors which drive and hinder the adoption of strategic SCM is also developed and presented

The role of sustainability assessment in sustainability management for urban redevelopment

Sustainability assessment has the potential to influence decision making and hence to improve the management of sustainability. This paper presents the development and reporting of benchmark sustainability indicators and discusses the challenges of embedding sustainability indicators into existing process for urban infrastructure development. It links sustainability indicators with a range of tools that were implemented within a Sustainability Enhancement and Monitoring Framework for the £1billion redevelopment of Dundee Waterfront. The sustainability monitoring framework followed the UK and Scottish Government thematic indicator approach and provided a set of Sustainability Benchmark Indicators for assessing and managing a public sector funded urban redevelopment. The process of indicator development was iterative and consisted of three main activities, literature, interviews and document analysis. Indicators were finalised through close working with Dundee City Council, Scottish Enterprise and partnership stakeholders. The indicators were successfully established in 2010 within Dundee City Council at project and departmental level, providing the link across policies, programmes and projects. The indictor development process is discussed and the findings of a January 2015 review of changes in the benchmark indicators will be reported. The transition of the indicators over time and its impact on future sustainability enhancement opportunities are evaluated alongside the implications for sustainability management of Dundee Waterfront. The efficacy of the benchmark indicators to support sustainability management over the planned 30 year programme of urban redevelopment is discussed. The wider implications of the findings of the Dundee Waterfront project are reviewed in the context of current work on sustainability assessment

Major project team learning:examining building information modelling

The speed of technological advancement of software development drives the need for individual and team learning to exploit these developments for competitive advantage. Using a major long term redevelopment as a case study a review of learning processes and project team learning in the context of a voluntary approach to adopting of BIM prior to 2016 is examined. The speed of adoption of BIM across a large redevelopment project covering several years is variable and the differences of preparedness between team members from different organisations raises the question of how effective the project team can be in sharing learning and increasing the speed of adoption of BIM. The benefits of understanding the project environment as a formal learning context are recognised where teams are working in partnering arrangements but the focus is usually on post project review of what went wrong with little time to critically evaluate other variables. Knowledge Management has the potential to help understand and then facilitate greater participation amongst stakeholders in project team learning. The research team undertook decision mapping and knowledge elicitation techniques and applied these to the Dundee Waterfront to identify key factors relevant to successful project management, enabling the Waterfront Project Team to understand current practice. The effectiveness of project team learning in relation to BIM within this long-term major redevelopment is influenced by positive motivational drivers for individuals to learn how to use and apply BIM, the level of organisational support for learning and professional development and the project information and communication systems. In practice the current approach to sharing of knowledge within the project team indicates a fragmented approach in relation to the adoption and application of BIM to managing construction projects

Assessing and supporting working memory in children: the role of attention and the environment

Working memory (WM) – the ability to store information over short periods of time in support of complex cognition – is implicated in a range of cognitive processes and developmental milestones. Given the importance of WM, it is vital that tools exist to rapidly but effectively assess this set of abilities. In Chapter 2 the development of computerised set of measures is described that we designed to facilitate rapid group testing in a school setting. These aims were defined by links with the Born in Bradford longitudinal cohort study. The rest of the thesis investigates how WM might be supported in children, a critical line of research considering the developmental implications of WM difficulties. In Chapter 3 the first investigation of the ability of children to prioritise serial positions within a visual sequence is presented. Children were instructed to try especially hard to remember either the first or third item in three-item sequences of shapes. Adults are consistently able to do this, resulting in superior performance for the prioritised item, at a cost to other items. Unlike adults, children did not show an ability to prioritise a particular position, when instructed to do so. Chapter 3 also includes a novel individual difference analysis that further clarifies the automaticity of recency effects in visual WM. Following the absence of prioritisation effects in Chapter 3, an alternative approach informed by embodied theories of cognition was taken in Chapter 4. Participants were presented with a WM task where the task environment was either structured pseudorandomly or in a task-relevant manner. This task-relevant organisation was consistently beneficial for children with low WM, such that they performed better than when the environment was structured. Children’s metacognitive understanding of the experimental manipulation was also investigated, highlighting the important of metacognitive factors to supporting WM in children

An approach to CMG steering using feedback linearization

This paper presents an approach for controlling spacecraft equipped with control moment gyroscopes. A technique from feedback linearization theory is used to transform the original nonlinear problem to an equivalent linear form without approximating assumptions. In this form, the spacecraft dynamics appear linearly, and are decoupled from redundancy in the system of gyroscopes. A general approach to distributing control effort among the available actuators is described which includes provisions for redistribution of rotors, explicit bounds in gimbal rates, and guaranteed operation at or near singular configurations. A particular algorithm is developed for systems of double-gimbal devices, and demonstrated in two examples for which existing approaches fail to give adequate performance

Sequence analysis of the cis-regulatory regions of the bithorax complex of Drosophila

The bithorax complex (BX-C) of Drosophila, one of two complexes that act as master regulators of the body plan of the fly, has now been entirely sequenced and comprises approximate to 315,000 bp, only 1.4% of which codes for protein. Analysis of this sequence reveals significantly overrepresented DNA motifs of unknown, as well as known, functions in the nonprotein-coding portion of the sequence. The following types of motifs in that portion are analyzed: (i) concatamers of mono-, di-, and trinucleotides; (ii) tightly clustered hexanucleotides (spaced less than or equal to 5 bases apart); (iii) direct and reverse repeats longer than 20 bp; and (iv) a number of motifs known from biochemical studies to play a role in the regulation of the BX-C. The hexanucleotide AGATAC is remarkably overrepresented and is surmised to play a role in chromosome pairing. The positions of sites of highly overrepresented motifs are plotted for those that occur at more than five sites in the sequence, when <0.5 case is expected. Expected values are based on a third-order Markov chain, which is the optimal order for representing the BXCALL sequence

The positional-specificity effect reveals a passive-trace contribution to visual short-term memory.

The positional-specificity effect refers to enhanced performance in visual short-term memory (VSTM) when the recognition probe is presented at the same location as had been the sample, even though location is irrelevant to the match/nonmatch decision. We investigated the mechanisms underlying this effect with behavioral and fMRI studies of object change-detection performance. To test whether the positional-specificity effect is a direct consequence of active storage in VSTM, we varied memory load, reasoning that it should be observed for all objects presented in a sub-span array of items. The results, however, indicated that although robust with a memory load of 1, the positional-specificity effect was restricted to the second of two sequentially presented sample stimuli in a load-of-2 experiment. An additional behavioral experiment showed that this disruption wasn't due to the increased load per se, because actively processing a second object--in the absence of a storage requirement--also eliminated the effect. These behavioral findings suggest that, during tests of object memory, position-related information is not actively stored in VSTM, but may be retained in a passive tag that marks the most recent site of selection. The fMRI data were consistent with this interpretation, failing to find location-specific bias in sustained delay-period activity, but revealing an enhanced response to recognition probes that matched the location of that trial's sample stimulus

Quantum thermodynamics for a model of an expanding universe

We investigate the thermodynamical properties of quantum fields in curved spacetime. Our approach is to consider quantum fields in curved spacetime as a quantum system undergoing an out-of-equilibrium transformation. The non-equilibrium features are studied by using a formalism which has been developed to derive fluctuation relations and emergent irreversible features beyond the linear response regime. We apply these ideas to an expanding universe scenario, therefore avoiding assumptions on the relation between entropy and quantum matter. We provide a fluctuation theorem which allows us to understand particle production due to the expansion of the universe as an entropic increase. Our results pave the way towards a different understanding of the thermodynamics of relativistic and quantum systems in our universe.Comment: 13 pages, no figures. I. Fuentes previously published as I. Fuentes-Guridi and I. Fuentes-Schulle

Season of birth and risk of developing idiopathic Parkinson's disease

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