Long-term characterization of the chronic dopamine microelectrode and effect of electrical conditioning

Background: Dopamine (DA) is a neurotransmitter involved in movement, reward learning and addiction. Fast-scan cyclic voltammetry (FSCV) has long been an indispensable tool for monitoring real-time DA signaling. Development of polyimide fused silica-encased FSCV microelectrodes have made the technique more suitable for chronic DA monitoring (months) in vivo. Methods: In this study, electrically stimulated DA signals were evoked weekly in an effort to characterize the recovery time and stability of DA signals recorded long-term with silica-encased chronic DA microelectrodes. Additionally, electrical conditioning (etching), previously shown to improve microelectrode sensitivity in vitro, was performed to investigate the long-term impact on DA monitoring in vivo. Changes in sensitivity were assessed by kinetic analysis of recorded DA signals resulting in parameters describing DA release ([DA][subscript p]; the concentration of DA release per stimulus pulse) and uptake (V[subscript max]; maximal rate of DA uptake). Results: Data from this study demonstrate that the peak amplitude of evoked DA signals (DA[subscript max]) significantly decreases after surgery, recovers in about 4.5 weeks, and then stabilizes and remains consistent long-term(\u3e 6 weeks). The same trend holds for kinetic parameters describing DA release and uptake. Additional data also demonstrate that electrical conditioning increases the magnitude and quality of DA signals recorded long- term in vivo. Conclusions: Once recovered, electrically evoked DA signals recorded at the silica- encased chronic DA microelectrode, and resulting kinetic parameters describing DA release and uptake, are stable long-term (months) and can be enhanced with electrical conditioning --Leaf iv

Tracking Vector Magnetograms with the Magnetic Induction Equation

The differential affine velocity estimator (DAVE) developed in Schuck (2006) for estimating velocities from line-of-sight magnetograms is modified to directly incorporate horizontal magnetic fields to produce a differential affine velocity estimator for vector magnetograms (DAVE4VM). The DAVE4VM's performance is demonstrated on the synthetic data from the anelastic pseudospectral ANMHD simulations that were used in the recent comparison of velocity inversion techniques by Welsch (2007). The DAVE4VM predicts roughly 95% of the helicity rate and 75% of the power transmitted through the simulation slice. Inter-comparison between DAVE4VM and DAVE and further analysis of the DAVE method demonstrates that line-of-sight tracking methods capture the shearing motion of magnetic footpoints but are insensitive to flux emergence -- the velocities determined from line-of-sight methods are more consistent with horizontal plasma velocities than with flux transport velocities. These results suggest that previous studies that rely on velocities determined from line-of-sight methods such as the DAVE or local correlation tracking may substantially misrepresent the total helicity rates and power through the photosphere.Comment: 30 pages, 13 figure

Model-based Cognitive Neuroscience: Multifield Mechanistic Integration in Practice

Autonomist accounts of cognitive science suggest that cognitive model building and theory construction (can or should) proceed independently of findings in neuroscience. Common functionalist justifications of autonomy rely on there being relatively few constraints between neural structure and cognitive function (e.g., Weiskopf, 2011). In contrast, an integrative mechanistic perspective stresses the mutual constraining of structure and function (e.g., Piccinini & Craver, 2011; Povich, 2015). In this paper, I show how model-based cognitive neuroscience (MBCN) epitomizes the integrative mechanistic perspective and concentrates the most revolutionary elements of the cognitive neuroscience revolution (Boone & Piccinini, 2016). I also show how the prominent subset account of functional realization supports the integrative mechanistic perspective I take on MBCN and use it to clarify the intralevel and interlevel components of integration

Direct calculation of the hard-sphere crystal/melt interfacial free energy

We present a direct calculation by molecular-dynamics computer simulation of the crystal/melt interfacial free energy, $\gamma$, for a system of hard spheres of diameter $\sigma$. The calculation is performed by thermodynamic integration along a reversible path defined by cleaving, using specially constructed movable hard-sphere walls, separate bulk crystal and fluid systems, which are then merged to form an interface. We find the interfacial free energy to be slightly anisotropic with $\gamma$ = 0.62$\pm 0.01$, 0.64$\pm 0.01$ and 0.58$\pm 0.01 k_BT/\sigma^2$ for the (100), (110) and (111) fcc crystal/fluid interfaces, respectively. These values are consistent with earlier density functional calculations and recent experiments measuring the crystal nucleation rates from colloidal fluids of polystyrene spheres that have been interpreted [Marr and Gast, Langmuir {\bf 10}, 1348 (1994)] to give an estimate of $\gamma$ for the hard-sphere system of $0.55 \pm 0.02 k_BT/\sigma^2$, slightly lower than the directly determined value reported here.Comment: 4 pages, 4 figures, submitted to Physical Review Letter

Closed-Neighborhood Anti-Sperner Graphs

For a simple graph G let NG[u] denote the closed-neighborhood of vertex u ∈ V (G). Then G is closed-neighborhood anti-Sperner (CNAS) if for every u there is a v ∈ V (G)\{u} with NG [u] ⊆ NG [v] and a graph H is closed-neighborhood distinct (CND) if every closed-neighborhood is distinct, i.e., if NH[u] ≠ NH[v] when u ≠ v, for all u and v ∈ V (H). In this paper we are mainly concerned with constructing CNAS graphs. We construct a family of connected CNAS graphs with n vertices for each fixed n ≥ 2. We list all connected CNAS graphs with ≤ 6 vertices, and find the smallest connected CNAS graph that lies outside these families. We indicate how some CNAS graphs can be constructed from a related type of graph, called a NAS graph. Finally, we present an algorithm to construct all CNAS graphs on a fixed number of vertices from labelled CND graphs on fewer vertices

The accidental environmentalists: Factors affecting farmers’ adoption of pro-environmental activities in England and Ontario

Based on semi-structured interviews with 54 distinct actors in the UK and Canada, we identify a range of internal psychological orientations that are common (albeit to varying degrees) in both case study regions that, when taken together, provide a lens through which on-farm decisions relating to pro-environmental behaviours are internally analysed and subsequently operationalised. We label these orientations as Production, Business, Environmental, Lifestyle, and Farm Health. Through these orientations, we find farmers are often becoming ‘accidental environmentalists’ by undertaking many pro-environmental activities for non-environmental reasons. Prominent examples include adopting environmentally beneficial on-farm decisions to support field sports (i.e. shooting), pursuing production improvements with environmental spin-offs (e.g. cover crops, beneficial pollinators), or seeking improvements to personal or family health and well-being (e.g. reduced use of chemicals). This analysis therefore highlights the importance of not oversimplifying farmer motivations along a dualistic profit-seeking v stewardship divide when it comes to understanding environmental behaviour