216 research outputs found
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Controlling a mobile robot with a biological brain
The intelligent controlling mechanism of a typical mobile robot is usually a computer system. Some recent research is ongoing in which biological neurons are being cultured and trained to act as the brain of an interactive real world robotïżœthereby either completely replacing, or operating in a cooperative fashion with, a computer system. Studying such hybrid systems can provide distinct insights into the operation of biological neural structures, and therefore, such research has immediate medical implications as well as enormous potential in robotics. The main aim of the research is to assess the computational and learning capacity of dissociated cultured neuronal networks. A hybrid system incorporating closed-loop control of a mobile robot by a dissociated culture of neurons has been created. The system is flexible and allows for closed-loop operation, either with hardware robot or its software simulation. The paper provides an overview of the problem area, gives an idea of the breadth of present ongoing research, establises a new system architecture and, as an example, reports on the results of conducted experiments with real-life robots
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Revealing ensemble state transition patterns in multi-electrode neuronal recordings using hidden Markov models
In order to harness the computational capacity of dissociated cultured neuronal networks, it is necessary to understand neuronal dynamics and connectivity on a mesoscopic scale. To this end, this paper uncovers dynamic spatiotemporal patterns emerging from electrically stimulated neuronal cultures using hidden Markov models (HMMs) to characterize multi-channel spike trains as a progression of patterns of underlying states of neuronal activity. However, experimentation aimed at optimal choice of parameters for such models is essential and results are reported in detail. Results derived from ensemble neuronal data revealed highly repeatable patterns of state transitions in the order of milliseconds in response to probing stimuli
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Spatio-temporal dependencies in functional connectivity in rodent cortical cultures
Models of functional connectivity in cortical cultures on multi-electrodes arrays may aid in understanding how cognitive pathways form and improve techniques that aim to interface with neuronal systems. To enable research on such models, this study uses both data- and model-driven approaches to determine what dependencies are present in and between functional connectivity networks derived from bursts of extracellularly recorded activity. Properties of excitation in bursts were analysed using correlative techniques to assess the degree of linear dependence and then two parallel techniques were used to assess functional connectivity. Three models presenting increasing levels of spatio-temporal dependency were used to capture the dynamics of individual functional connections and their consistencies were verified using surrogate data. By comparing network-wide properties between model generated networks and functional networks from data, complex interdependencies were revealed. This indicates the persistent co-activation of neuronal pathways in spontaneous bursts, as can be found in whole brain structures
On the equivalence of the Einstein-Hilbert and the Einstein-Palatini formulations of general relativity for an arbitrary connection
In the framework of the Einstein-Palatini formalism, even though the
projective transformation connecting the arbitrary connection with the Levi
Civita connection has been floating in the literature for a long time and
perhaps the result was implicitly known in the affine gravity community, yet as
far as we know Julia and Silva were the first to realise its gauge character.
We rederive this result by using the Rosenfeld-Dirac-Bergmann approach to
constrained Hamiltonian systems and do a comprehensive self contained analysis
establishing the equivalence of the Einstein-Palatini and the metric
formulations without having to impose the gauge choice that the connection is
symmetric. We also make contact with the the Einstein-Cartan theory when the
matter Lagrangian has fermions.Comment: 18 pages. Slight change in the title and wording of some sections to
emphasize the main results. References added. Matches published versio
Design and methods of Shape Up Under 5: Integration of systems science and community-engaged research to prevent early childhood obesity
Shape Up Under 5 (SUU5) was a two-year early childhood obesity prevention pilot study in Somerville, Massachusetts (2015â2017) designed to test a novel conceptual framework called Stakeholder-driven Community Diffusion. For whole-of-community interventions, this framework posits that diffusion of stakeholdersâ knowledge about and engagement with childhood obesity prevention efforts through their social networks will improve the implementation of health-promoting policy and practice changes intended to reduce obesity risk. SUU5 used systems science methods (agent-based modeling, group model building, social network analysis) to design, facilitate, and evaluate the work of 16 multisector stakeholders (âthe Committeeâ). In this paper, we describe the design and methods of SUU5 using the conceptual framework: the approach to data collection, and methods and rationale for study inputs, activities and evaluation, which together may further our understanding of the hypothesized processes within Stakeholder-driven Community Diffusion. We also present a generalizable conceptual framework for addressing childhood obesity and similar complex public health issues through whole-of-community interventions
Qualitative Examination of Voting Empowerment and Participation Among People Living With Traumatic Brain Injury
Objective
To examine political participation after traumatic brain injury (TBI).
Design
Qualitative, participatory research via interviews and observations. Each participant was interviewed to discuss their experience of voting in 2007 or 2008. Data were coded using Grounded Theory to develop themes, metacodes, and theories.
Setting
Community.
Participants
A total of 57 individuals with history of TBI and 28 family members (N=85).
Main Outcome Measures
Not applicable.
Results
Four themes emerged from the data: (1) people with TBI have barriers to voting; (2) the voting process can be improved for people with TBI; (3) voting is the responsibility of members of society; and (4) voting is one way we have a voice in society.
Conclusions
The data support the importance of voting as an American right regardless of the presence of disability. While persons with TBI report voting represents their freedom and voice, there may be barriers that can threaten or limit their voice
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A randomised controlled trial of memory flexibility training (MemFlex) to enhance memory flexibility and reduce depressive symptomatology in individuals with major depressive disorder.
UNLABELLED: Successful navigation within the autobiographical memory store is integral to daily cognition. Impairment in the flexibility of memory retrieval can thereby have a detrimental impact on mental health. This randomised controlled phase II exploratory trial (NâŻ=âŻ60) evaluated the potential of a novel intervention drawn from basic science - an autobiographical Memory Flexibility (MemFlex) training programme - which sought to ameliorate memory difficulties and improve symptoms of Major Depressive Disorder. MemFlex was compared to Psychoeducation (an evidence-based low-intensity intervention) to determine the likely range of effects on a primary cognitive target of memory flexibility at post-intervention, and co-primary clinical targets of self-reported depressive symptoms and diagnostic status at three-month follow-up. These effect sizes could subsequently be used to estimate sample size for a fully-powered trial. Results demonstrated small-moderate, though as expected statistically non-significant, effect sizes in favour of MemFlex for memory flexibility (dâŻ=âŻ0.34, pâŻ=âŻ.20), and loss of diagnosis (ORâŻ=âŻ0.65, pâŻ=âŻ.48), along with the secondary outcome of depression-free days (dâŻ=âŻ0.36, pâŻ=âŻ.18). A smaller effect size was observed for between-group difference in self-reported depressive symptoms (dâŻ=âŻ0.24, pâŻ=âŻ.35). Effect sizes in favour of MemFlex in this early-stage trial suggest that fully-powered evaluation of MemFlex may be warranted as an avenue to improving low-intensity treatment of depression. TRIAL REGISTRATION: ClinicalTrials.gov, Identifier NCT02371291
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Association of Genetic Variants With Primary Open-Angle Glaucoma Among Individuals With African Ancestry.
Importance:Primary open-angle glaucoma presents with increased prevalence and a higher degree of clinical severity in populations of African ancestry compared with European or Asian ancestry. Despite this, individuals of African ancestry remain understudied in genomic research for blinding disorders. Objectives:To perform a genome-wide association study (GWAS) of African ancestry populations and evaluate potential mechanisms of pathogenesis for loci associated with primary open-angle glaucoma. Design, Settings, and Participants:A 2-stage GWAS with a discovery data set of 2320 individuals with primary open-angle glaucoma and 2121 control individuals without primary open-angle glaucoma. The validation stage included an additional 6937 affected individuals and 14âŻ917 unaffected individuals using multicenter clinic- and population-based participant recruitment approaches. Study participants were recruited from Ghana, Nigeria, South Africa, the United States, Tanzania, Britain, Cameroon, Saudi Arabia, Brazil, the Democratic Republic of the Congo, Morocco, Peru, and Mali from 2003 to 2018. Individuals with primary open-angle glaucoma had open iridocorneal angles and displayed glaucomatous optic neuropathy with visual field defects. Elevated intraocular pressure was not included in the case definition. Control individuals had no elevated intraocular pressure and no signs of glaucoma. Exposures:Genetic variants associated with primary open-angle glaucoma. Main Outcomes and Measures:Presence of primary open-angle glaucoma. Genome-wide significance was defined as Pâ<â5âĂâ10-8 in the discovery stage and in the meta-analysis of combined discovery and validation data. Results:A total of 2320 individuals with primary open-angle glaucoma (mean [interquartile range] age, 64.6 [56-74] years; 1055 [45.5%] women) and 2121 individuals without primary open-angle glaucoma (mean [interquartile range] age, 63.4 [55-71] years; 1025 [48.3%] women) were included in the discovery GWAS. The GWAS discovery meta-analysis demonstrated association of variants at amyloid-ÎČ A4 precursor protein-binding family B member 2 (APBB2; chromosome 4, rs59892895T>C) with primary open-angle glaucoma (odds ratio [OR], 1.32 [95% CI, 1.20-1.46]; Pâ=â2âĂâ10-8). The association was validated in an analysis of an additional 6937 affected individuals and 14âŻ917 unaffected individuals (OR, 1.15 [95% CI, 1.09-1.21]; Pâ<â.001). Each copy of the rs59892895*C risk allele was associated with increased risk of primary open-angle glaucoma when all data were included in a meta-analysis (OR, 1.19 [95% CI, 1.14-1.25]; Pâ=â4âĂâ10-13). The rs59892895*C risk allele was present at appreciable frequency only in African ancestry populations. In contrast, the rs59892895*C risk allele had a frequency of less than 0.1% in individuals of European or Asian ancestry. Conclusions and Relevance:In this genome-wide association study, variants at the APBB2 locus demonstrated differential association with primary open-angle glaucoma by ancestry. If validated in additional populations this finding may have implications for risk assessment and therapeutic strategies
Critical materials for infrastructure: local vs global properties
Introducing new technologies into infrastructure (wind turbines, electric vehicles, low-carbon materials and so on) often demands materials that are âcriticalâ; their supply is likely to be disrupted owing to limited reserves, geopolitical instability, environmental issues and/or increasing demand. Non-critical materials may become critical if introduced into infrastructure, owing to its gigatonne scale. This potentially poses significant risk to the development of low-carbon infrastructure. Analysis of this risk has previously overlooked the relationship between the âlocal propertiesâ that determine the selection of a technology and the overall vulnerability of the system, a global property. Treating materials or components as elements having fixed properties overlooks optima within the localâglobal variable space that could be exploited to minimise vulnerability while maximising performance. In this study, a framework for such analysis is presented along with a preliminary measure of relative materials criticality by way of a case study (a wind turbine generator). Although introduction of critical materials (in this case, rare earth metals) enhances technical performance by up to an order of magnitude, the associated increase in criticality may be two or three orders of magnitude. Analysis at the materials and component levels produces different results; design decisions should be based on analysis at several levels
Associations with intraocular pressure across Europe: The European Eye Epidemiology (E3) Consortium.
Raised intraocular pressure (IOP) is the most important risk factor for developing glaucoma, the second commonest cause of blindness globally. Understanding associations with IOP and variations in IOP between countries may teach us about mechanisms underlying glaucoma. We examined cross-sectional associations with IOP in 43,500 European adults from 12 cohort studies belonging to the European Eye Epidemiology (E3) consortium. Each study conducted multivariable linear regression with IOP as the outcome variable and results were pooled using random effects meta-analysis. The association of standardized study IOP with latitude was tested using meta-regression. Higher IOP was observed in men (0.18Â mmHg; 95Â % CI 0.06, 0.31; PÂ =Â 0.004) and with higher body mass index (0.21Â mmHg per 5Â kg/m2; 95Â % CI 0.14, 0.28; PÂ <Â 0.001), shorter height (-0.17Â mmHg per 10Â cm; 95Â % CI -0.25, -0.08; PÂ <Â 0.001), higher systolic blood pressure (0.17Â mmHg per 10Â mmHg; 95Â % CI 0.12, 0.22; PÂ <Â 0.001) and more myopic refraction (0.06Â mmHg per Dioptre; 95Â % CI 0.03, 0.09; PÂ <Â 0.001). An inverted U-shaped trend was observed between age and IOP, with IOP increasing up to the age of 60 and decreasing in participants older than 70Â years. We found no significant association between standardized IOP and study location latitude (PÂ =Â 0.76). Novel findings of our study include the association of lower IOP in taller people and an inverted-U shaped association of IOP with age. We found no evidence of significant variation in IOP across Europe. Despite the limited range of latitude amongst included studies, this finding is in favour of collaborative pooling of data from studies examining environmental and genetic determinants of IOP in Europeans.Medical Research Council (G1000143), Cancer Research UK (C864/A14136), Research into Ageing (262), Wellcome Trust, Richard Desmond Charitable Trust (via Fight for Sight), National Institute for Health Research, Stichting Lijf en Leven, Krimpen aan de Lek, MD Fonds, Utrecht, Rotterdamse Vereniging Blindenbelangen, Rotterdam, Stichting Oogfonds Nederland, Utrecht, Blindenpenning, Amsterdam, Blindenhulp, The Hague, Algemene Nederlandse Vereniging ter Voorkoming van Blindheid (ANVVB), Doorn, Landelijke Stichting voor Blinden en Slechtzienden, Utrecht, Swart van Essen, Rotterdam, Stichting Winckel-Sweep, Utrecht, Henkes Stichting, Rotterdam, Lameris Ootech BV, Nieuwegein, Medical Workshop, de Meern, NWO (Graduate Programme 2010 BOO (022.002.023)), Laboratoires Thea (Clermont-Ferrand, France), inter regional grant (PHRC) and the regional Council of Burgundy, European Communityâs Seventh Framework Programme (FP7/2007-2013), Rheinland-Pfalz AZ 961-386261/733), Johannes Gutenberg-University of Mainz, Boehringer Ingelheim, PHILIPS Medical Systems, Novartis Pharma, Novartis European Union (European Social FundâESF), Greek National Strategic Reference Framework (NSRF) (Research Funding Program: THALES), European Social FundThis is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s10654-016-0191-
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