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

Project communication variables : a comparative study of US and UK industry perceptions

Research undertaken at the Construction Industry Institute (CII) in the USA has indicated the need for project managers to focus their attention on six ‘Critical Communication Variables’ as a means of ensuring the fulfillment of time cost and quality targets. These variables refer to the accuracy, timeliness and completeness of information presented to participants, as well as the level of understanding, barriers to and procedures for project based communication. The findings and tools generated by the CII study have been used as part of case study based research examining construction projects in the Central Belt region of Scotland. In addition to the CII data collection tools employed, the Scottish study included semi-structured interviews as a means of contextualising the communication and decision-making taking place. This paper presents the results of this benchmarking exercise, and highlights significant issues that project team members need to improve upon in order to achieve the timeliness quality and cost required in today’s construction industr

Beyond binomial and negative binomial: adaptation in Bernoulli parameter estimation

Estimating the parameter of a Bernoulli process arises in many applications, including photon-efficient active imaging where each illumination period is regarded as a single Bernoulli trial. Motivated by acquisition efficiency when multiple Bernoulli processes (e.g., multiple pixels) are of interest, we formulate the allocation of trials under a constraint on the mean as an optimal resource allocation problem. An oracle-aided trial allocation demonstrates that there can be a significant advantage from varying the allocation for different processes and inspires the introduction of a simple trial allocation gain quantity. Motivated by achieving this gain without an oracle, we present a trellis-based framework for representing and optimizing stopping rules. Considering the convenient case of Beta priors, three implementable stopping rules with similar performances are explored, and the simplest of these is shown to asymptotically achieve the oracle-aided trial allocation. These approaches are further extended to estimating functions of a Bernoulli parameter. In simulations inspired by realistic active imaging scenarios, we demonstrate significant mean-squared error improvements up to 4.36 dB for the estimation of p and up to 1.86 dB for the estimation of log p.https://arxiv.org/abs/1809.08801https://arxiv.org/abs/1809.08801First author draf

Nested sampling for Potts models

Nested sampling is a new Monte Carlo method by Skilling [1] intended for general Bayesian computation. Nested sampling provides a robust alternative to annealing-based methods for computing normalizing constants. It can also generate estimates of other quantities such as posterior expectations. The key technical requirement is an ability to draw samples uniformly from the prior subject to a constraint on the likelihood. We provide a demonstration with the Potts model, an undirected graphical model

Beyond Binomial and Negative Binomial: Adaptation in Bernoulli Parameter Estimation

Estimating the parameter of a Bernoulli process arises in many applications, including photon-efficient active imaging where each illumination period is regarded as a single Bernoulli trial. Motivated by acquisition efficiency when multiple Bernoulli processes are of interest, we formulate the allocation of trials under a constraint on the mean as an optimal resource allocation problem. An oracle-aided trial allocation demonstrates that there can be a significant advantage from varying the allocation for different processes and inspires a simple trial allocation gain quantity. Motivated by realizing this gain without an oracle, we present a trellis-based framework for representing and optimizing stopping rules. Considering the convenient case of Beta priors, three implementable stopping rules with similar performances are explored, and the simplest of these is shown to asymptotically achieve the oracle-aided trial allocation. These approaches are further extended to estimating functions of a Bernoulli parameter. In simulations inspired by realistic active imaging scenarios, we demonstrate significant mean-squared error improvements: up to 4.36 dB for the estimation of p and up to 1.80 dB for the estimation of log p.Comment: 13 pages, 16 figure

Cardiac and renal function are progressively impaired with aging in Zucker diabetic fatty type II diabetic rats

This study investigated the temporal relationship between cardiomyopathy and renal pathology in the type II diabetic Zucker diabetic fatty (ZDF) rat. We hypothesized that changes in renal function will precede the development of cardiac dysfunction in the ZDF rat. Animals (10 weeks old) were divided into four experimental groups: Lean Control (fa/?) LC (n = 7), untreated ZDF rats (n = 7) sacrificed at 16 weeks of age, and LC (n = 7) untreated ZDF rats (n = 9) sacrificed at 36 weeks of age. LV structural/functional parameters were assessed via Millar conductance catheter. Renal function was evaluated via markers of proteinuria and evidence of hydronephrosis. LV mass was significantly less in the ZDF groups at both time points compared to age-matched LC. End diastolic volume was increased by 16% at 16 weeks and by 37% at 36 weeks of age (p < 0.05 vs. LC). End diastolic pressure and end systolic volume were significantly increased (42% and 27% respectively) at 36 weeks of age in the ZDF compared to LC. Kidney weights were significantly increased at both 16 and 36 week in ZDF animals (p < 0.05 vs. LC). Increased urinary albumin and decreased urinary creatinine were paralleled by a marked progression in the severity of hydronephrosis from 16 to 36 weeks of age in the ZDF group. In summary, there is evidence of progressive structural and functional changes in both the heart and kidney, starting as early as 16 weeks, without evidence that one pathology precedes or causes the other in the ZDF model of type II diabetes

Learn from yesterday, live for today, hope for tomorrow : attempting to plan for coastal change in South West Victoria

Learn from yesterday, live for today hope for tomorrow. When Albert Einstein penned these opening words, the realm of planning was least on his mind despite the aptness of the thoughts. This paper, having regard to this quotation, questions whether demographic change in one coastal area is occurring at a faster rate than in non&ndash;coastal areas? The South West coastal area of Victoria, from 1981 onwards, has witnessed a dramatic increase in population and also major shifts in the social and economic characteristics of the region. What have been the historic demographic and employment characteristics of the area and has there been a shift in these characteristics leading to the rapid population growth? These questions are considered using the City of Warrnambool, the largest urban centre in South West Victoria, as a study vehicle. The impact of a growing population on the municipal landscape can be demanding in terms of land use planning, land supply and the urban design. This paper will review the population growth using a shift share analysis method compared against overall growth patterns in the Victorian state population and Australia overall. It will then examine government population forecasts for the City of Warrnambool and suggest those impacts upon the current City of Warrnambool landscape

Review of recirculation aquaculture system technologies and their commercial application

Recirculation aquaculture systems (RAS) are designed to minimise water consumption, control culture conditions and allow waste streams to be fully managed. They can also provide some degree of biosecurity through measures to isolate the stock from the external environment. RAS technology has steadily developed over the past 30 years and is widely used for broodstock management, in hatcheries and increasingly for salmon smolt production. By comparison, the progress of RAS for grow-out to market size products has been more restricted and there is a substantial track record of company failures both in the UK, Europe and internationally. The reasons for this are varied, but include challenges of economic viability and operating systems at commercial scales. This review considers the current status of RAS technology and its commercial application with particular reference to its potential impact on Scottish aquaculture. With increased reliability and efficiency new opportunities are open to the Scottish industry to both enhance salmon production and diversify to other species. On the other hand, the greater flexibility in locating RAS farms could present a threat to some salmon production in Scotland where production can move closer to key centres of consumption &ndash; either in the UK or abroad. After all, one of the environmental advantages of RAS is to enable production in areas unsuited to other forms of aquaculture and where promotion of sustainability is a key element. Consequently, farming close to markets, thereby reducing food miles, may have benefits for both the retailer and consumer. However, what proportion of caged salmon production might eventually be substituted by land based RAS is debateable. This may depend on the economic advantage to some current salmon export markets farming salmon in their own country using RAS technology developed in Europe or North America.Report commissioned by Highlands & Islands Enterprise as strategic support to the Scottish Food and Drink Industr

An update on the 2014 report: "Review of Recirculation Aquaculture System Technologies and their Commercial Application"

This report has been commissioned by Highlands and Islands Enterprise to provide an update on the earlier report "Review of Recirculation Aquaculture System Technologies and their Commercial Application" from the same authors and published in 2014. The leading salmon aquaculture companies are all making strategic investments in RAS, mainly for juvenile production. This has been a trend over the past 20 years and has contributed substantially to technology development. The established industry has therefore demonstrated a willingness to adopt RAS technologies where they perceive a strong business case, such as enabling more consistent year-round supplies of juveniles. Parallel to the strategic adoption of RAS by existing salmon producers has been a series of RAS based grow-out projects based on a mix of optimistic technology promises and ethically driven enthusiasm for land-based farming drawing in investment from equity investors as well as government and other non-government organisations. Most of these have experienced a range of technical, financial and market problems and have either failed completely or are operating at a loss. Nevertheless, there is substantial momentum and lessons are being learned and technology is developing at a faster rate than when previously assessed in 2014. The lack of investment in grow-out RAS by established producers, notably salmon companies already culturing smolts in RAS, may reflect their greater understanding of market and economic fundamentals and/or reluctance to invest in disruptive technology given their heavy investments in cage grow-out production. More encouragingly, entry into the RAS sector by major water and sanitation companies such as Veolia, capable of more standardised technology development suggests previous barriers will be overcome. The immediate interest of the Scottish salmon industry is in strategies to reduce the impact of sea lice and other disease problems. One element of this is to reduce the time the fish are in sea cages through the stocking of post-smolts of between 250g and 1 kg in weight. It appears likely that landbased RAS could provide an economic means of achieving this, although sea-based closed containment systems are also being investigated as a potential alternative. Land-based RAS are also being used for cleaner fish production as another part of the sea lice control strategy. RAS offers opportunities for new species development in Scotland, with examples including sturgeon (caviar), yellow tail, sole, tropical shrimp, and spiny lobster. However, these are generally high value products for which domestic markets may be more limited. If already planned investments in salmon grow-out RAS go ahead in the USA, China and other important export markets for Scotland, long-term market opportunities are likely to be affected. A more substantial risk to the Scottish industry in the short to medium term could be a further decline in social license necessary to achieve ambitious growth-targets due to perceived conflicts with environmental and conservation targets. For this reason, combined with steadily maturing technology and new species opportunities, it is anticipated that aquaculture production using recirculated aquaculture systems will gradually expand in the coming years.Consultancy report produced under contract with Ekos Limited for Highlands and Islands Enterprise. Update of previous 2014 report on the same topic

Observation of Motion Dependent Nonlinear Dispersion with Narrow Linewidth Atoms in an Optical Cavity

As an alternative to state-of-the-art laser frequency stabilisation using ultra-stable cavities, it has been proposed to exploit the non-linear effects from coupling of atoms with a narrow transition to an optical cavity. Here we have constructed such a system and observed non-linear phase shifts of a narrow optical line by strong coupling of a sample of strontium-88 atoms to an optical cavity. The sample temperature of a few mK provides a domain where the Doppler energy scale is several orders of magnitude larger than the narrow linewidth of the optical transition. This makes the system sensitive to velocity dependent multi-photon scattering events (Dopplerons) that affect the cavity field transmission and phase. By varying the number of atoms and the intra-cavity power we systematically study this non-linear phase signature which displays roughly the same features as for much lower temperature samples. This demonstration in a relatively simple system opens new possibilities for alternative routes to laser stabilization at the sub 100 mHz level and superradiant laser sources involving narrow line atoms. The understanding of relevant motional effects obtained here has direct implications for other atomic clocks when used in relation with ultranarrow clock transitions.Comment: 9 pages (including 4 pages of Supplemental Information), 6 figures. Updated to correspond to the published versio