Eigenvalue Distributions for a Class of Covariance Matrices with Applications to Bienenstock-Cooper-Munro Neurons Under Noisy Conditions

We analyze the effects of noise correlations in the input to, or among, BCM neurons using the Wigner semicircular law to construct random, positive-definite symmetric correlation matrices and compute their eigenvalue distributions. In the finite dimensional case, we compare our analytic results with numerical simulations and show the effects of correlations on the lifetimes of synaptic strengths in various visual environments. These correlations can be due either to correlations in the noise from the input LGN neurons, or correlations in the variability of lateral connections in a network of neurons. In particular, we find that for fixed dimensionality, a large noise variance can give rise to long lifetimes of synaptic strengths. This may be of physiological significance.Comment: 7 pages, 7 figure

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A simple rule for axon outgrowth and synaptic competition generates realistic connection lengths and filling fractions

Neural connectivity at the cellular and mesoscopic level appears very specific and is presumed to arise from highly specific developmental mechanisms. However, there are general shared features of connectivity in systems as different as the networks formed by individual neurons in Caenorhabditis elegans or in rat visual cortex and the mesoscopic circuitry of cortical areas in the mouse, macaque, and human brain. In all these systems, connection length distributions have very similar shapes, with an initial large peak and a long flat tail representing the admixture of long-distance connections to mostly short-distance connections. Furthermore, not all potentially possible synapses are formed, and only a fraction of axons (called filling fraction) establish synapses with spatially neighboring neurons. We explored what aspects of these connectivity patterns can be explained simply by random axonal outgrowth. We found that random axonal growth away from the soma can already reproduce the known distance distribution of connections. We also observed that experimentally observed filling fractions can be generated by competition for available space at the target neurons--a model markedly different from previous explanations. These findings may serve as a baseline model for the development of connectivity that can be further refined by more specific mechanisms.Comment: 31 pages (incl. supplementary information); Cerebral Cortex Advance Access published online on May 12, 200

Piroplasms in brown hyaenas (Parahyaena brunnea) and spotted hyaenas (Crocuta crocuta) in Namibia and South Africa are closely related to Babesia lengau

The objective of our study was identification and molecular characterisation of piroplasms and rickettsias occurring in brown (Parahyaena brunnea) and spotted hyaenas (Crocuta crocuta) from various localities in Namibia and South Africa. Whole blood (n=59) and skin (n=3) specimens from brown (n=15) and spotted hyaenas (n=47) were screened for the presence of Babesia, Theileria, Ehrlichia and Anaplasma species using the Reverse Line Blot (RLB) hybridization technique. PCR products of 52/62 (83.9%) of the specimens hybridized only with the Theileria/Babesia genus-specific probes and not with any of the species-specific probes, suggesting the presence of a novel species or variant of a species. No Ehrlichia and/or Anaplasma species DNA could be detected. Parasite 18S rRNA gene of brown (n=3) and spotted hyaena (n=6) specimens was subsequently amplified, cloned and the recombinants sequenced. Homologous sequence searches of databases indicated that the obtained sequences were most closely related to B. lengau, originally described from cheetahs (Acinonyx jubatus). Observed sequence similarities were subsequently confirmed by phylogenetic analyses which showed that the obtained hyaena sequences formed a monophyletic group with B. lengau, B. conradae and sequences previously isolated from humans and wildlife in the western USA. Within the B. lengau clade, the obtained sequences and the published B. lengau sequences grouped into six distinct groups, of which groups I to V represented novel B. lengau genotypes and/or gene variants. We suggest that these genotypes cannot be classified as new Babesia species, but rather as variants of B. lengau. This is the first report of occurrence of piroplasms in brown hyaenas.http://link.springer.com/journal/4362018-02-28hb2017Centre for Veterinary Wildlife StudiesVeterinary Tropical Disease

Significant variability exists in preoperative planning software measures of glenoid morphology for shoulder arthroplasty

Background & Hypothesis: We sought to assess the reliability of 4 different shoulder arthroplasty 3-dimensional preoperative planning programs. Comparison was also made to manual measurements conducted by 2 fellowship-trained musculoskeletal radiologists. We hypothesized that there would be significant variation in measurements of glenoid anatomy affected by glenoid deformity. Methods: A retrospective review of computed tomography (CT) scans of patients undergoing shoulder arthroplasty was undertaken. A total of 76 computed tomographies were analyzed for glenoid version and inclination by 4 templating software systems (VIP, Blueprint, TrueSight, ExactechGPS). Inter-rater reliability was assessed via intra-class correlation coefficient (ICC). For those shoulders with glenohumeral arthritis (58/76), ICC was also calculated when sub-grouping by modified Walch classification. Lin\u27s concordance correlation coefficient was calculated for each system with 2 musculoskeletal-trained radiologists’ measurements. Results: Measurements of glenoid version and inclination differed between at least 2 programs by 5º-10º in 75% and 92% of glenoids respectively, and by \u3e10º in 18% and 45% respectively. ICC was excellent for version but only moderate for inclination. ICC was highest among Walch A glenoids for both version (near excellent) and inclination (good), and lowest among Walch D for version (near poor) and Walch B for inclination (moderate). When measuring version, VIP had the highest concordance with manual measurement; Blueprint had the lowest. For inclination Blueprint had the highest concordance; ExactechGPS had the lowest. Discussion & Conclusion: Despite overall high reliability for measures of glenoid version between 4 frequently utilized shoulder arthroplasty templating softwares, this reliability is significantly affected by glenoid deformity. The programs were overall less reliable when measuring inclination, and a similar trend of decreasing reliability with increasing glenoid deformity emerged that was not statistically significant. Concordance with manual measurement is also variable. Further research is needed to understand how this variability should be accounted for during shoulder arthroplasty preoperative planning. Level of Evidence: Level III; Retrospective Comparative Stud

Study protocol: developing a decision system for inclusive housing: applying a systematic, mixed-method quasi-experimental design

Background Identifying the housing preferences of people with complex disabilities is a much needed, but under-developed area of practice and scholarship. Despite the recognition that housing is a social determinant of health and quality of life, there is an absence of empirical methodologies that can practically and systematically involve consumers in this complex service delivery and housing design market. A rigorous process for making effective and consistent development decisions is needed to ensure resources are used effectively and the needs of consumers with complex disability are properly met. Methods/Design This 3-year project aims to identify how the public and private housing market in Australia can better respond to the needs of people with complex disabilities whilst simultaneously achieving key corporate objectives. First, using the Customer Relationship Management framework, qualitative (Nominal Group Technique) and quantitative (Discrete Choice Experiment) methods will be used to quantify the housing preferences of consumers and their carers. A systematic mixed-method, quasi-experimental design will then be used to quantify the development priorities of other key stakeholders (e.g., architects, developers, Government housing services etc.) in relation to inclusive housing for people with complex disabilities. Stakeholders randomly assigned to Group 1 (experimental group) will participate in a series of focus groups employing Analytical Hierarchical Process (AHP) methodology. Stakeholders randomly assigned to Group 2 (control group) will participate in focus groups employing existing decision making processes to inclusive housing development (e.g., Risk, Opportunity, Cost, Benefit considerations). Using comparative stakeholder analysis, this research design will enable the AHP methodology (a proposed tool to guide inclusive housing development decisions) to be tested. Discussion It is anticipated that the findings of this study will enable stakeholders to incorporate consumer housing preferences into commercial decisions. Housing designers and developers will benefit from the creation of a parsimonious set of consumer-led housing preferences by which to make informed investments in future housing and contribute to future housing policy. The research design has not been applied in the Australian research context or elsewhere, and will provide a much needed blueprint for market investment to develop viable, consumer directed inclusive housing options for people with complex disability