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

Sparing or sharing? Differing approaches to managing agricultural and environmental spaces in England and Ontario

The ability to balance agricultural production and environmental conservation in the face of increasing demand for food, fuel and fibre poses a major challenge for governments around the world. This challenge is explored in two areas of comparison: Ontario, Canada and England, UK in order to understand how each has balanced agriculture and environment in its land use policies. England and Ontario share similarities that suggest lessons and instruments may be transferrable to achieve similar land use objectives. Through the use of a thematic analysis of policy documentation, from each case study area, themes are identified demonstrating differences in approaches, and underlying policy preferences, associated with balancing agriculture and the environment. Specifically, results suggest that policymakers in Ontario hold a preference for land-sparing and leanings towards the productivist paradigm, whereas the land-sharing approach coupled with evidence of post-productivism is more common in England. The structural similarities of these cases provides insights into less tangible aspects of either context, such as policymaker preferences, where different approaches have emerged from a similar foundation. Moreover, as England transitions out of the EU, it may draw on the experiences of other jurisdictions in the design of a new suite of agri-environmental policies, with Ontario's approach providing one alternative. Overall, this paper contributes to our understanding of the manifestation of land-sparing/sharing and productivism/post-productivism in real world policy contexts and the relationship between both sets of concepts

Food production or environmental conservation: competition for land in the United Kingdom and Canada

With a growing global population projected to surpass 9 billion by 2050, and associated food demand anticipated to increase by 70 to 100%, food security has emerged as a land-use challenge of critical importance. This has raised concerns regarding how increased agricultural production can be achieved without compromising the natural environment. This challenge of balancing agricultural and environmental land-uses occurs at a range of scales addressed by this research, beginning with high level policies and working down towards farmers, the actors ultimately responsible for the management of arable land. The study was comprised of three interconnected research projects completed in two regions of comparison: Ontario, Canada and England, United Kingdom. First, I compared the agri-environmental land-use policy context of both cases through a thematic analysis of policy documentation. Second, I completed 24 interviews with representatives of agricultural and environmental stakeholder organisations to examine the agri-environmental land-use preferences of these actors. Third, I conducted 30 interviews with farmers to investigate their views and motivations relating to the adoption of pro-environmental activities. In addition, due to the timing of the research, an unanticipated opportunity arose to explore the views of stakeholder organisations and farmers in England on post-Brexit agri-environmental policy. Overall, my main finding was that England and Ontario have taken very different approaches to managing competition between agricultural and environmental land-uses with Ontario leaning towards land-sparing and England toward land-sharing. I found that this may be partially explained by different stakeholder preferences for agri-environmental land allocation and the attachment of actors to different agricultural paradigms (productivism / post-productivism). Importantly, the use of an original multi-level comparison of agri-environmental land-use in England and Ontario illuminated many similarities and differences that would not have been apparent in the analysis of a single case. As a result, the thesis offers multiple contributions to knowledge for rural, land-use, and comparative studies

Physico-Chemical Characteristics of Evaporating Respiratory Fluid Droplets

The detailed physico-chemical characteristics of respiratory droplets in ambient air, where they are subject to evaporation, are poorly understood. Changes in the concentration and phase of major components in a droplet—salt (NaCl), protein (mucin) and surfactant (dipalmitoylphosphatidylcholine)—may affect the viability of any pathogens contained within it and thus may affect the efficiency of transmission of infectious disease by droplets and aerosols. The objective of this study is to investigate the effect of relative humidity (RH) on the physico-chemical characteristics of evaporating droplets of model respiratory fluids. We labelled these components in model respiratory fluids and observed evaporating droplets suspended on a superhydrophobic surface using optical and fluorescence microscopy. When exposed to continuously decreasing RH, droplets of different model respiratory fluids assumed different morphologies. Loss of water induced phase separation as well as indication of a decrease in pH. The presence of surfactant inhibited the rapid rehydration of the non-volatile components. An enveloped virus, ϕ6, that has been proposed as a surrogate for influenza virus appeared to be homogeneously distributed throughout the dried droplet. We hypothesize that the increasing acidity and salinity in evaporating respiratory droplets may affect the structure of the virus, although at low enough RH, crystallization of the droplet components may eliminate their harmful effects

Beyond rescue: Implementation and evaluation of revised naloxone training for law enforcement officers

ObjectiveThis study describes the implementation and evaluation of revised opioid overdose prevention and education of naloxone training for law enforcement officers (LEOs) that added: (1) a recovery testimony and (2) the process for deputy‐initiated referrals postnaloxone administration.Design and SampleEvaluation regarding the naloxone training included a pre‐ and postopioid overdose knowledge surveys (N = 114) and subsequent 1‐year postnaloxone training outcomes.ResultsPre‐ and posttest scores for all knowledge outcome measures were statistically significant (p < .001) with favorable comments pertaining to the recovery testimony. Out of 31 individuals who received naloxone, 6 individuals (19.4%) continue to be in treatment or received some treatment services. The most common symptoms reported were unconsciousness/unresponsiveness (40.5%), abnormal breathing patterns (24.3%), and blue lips (16.2%). The majority of the calls (65.6%) were to a residential area, and the time for naloxone revival ranged <1–10 min (M = 3.48; SD = 2.27).ConclusionAs nearly 20% of individuals sought treatment after a LEO‐initiated referral, it is recommended that other agencies consider the referral process into the training. Future research will investigate the impact of the recovery testimony in reducing the stigma of addiction.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139953/1/phn12365_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139953/2/phn12365.pd

High Aspect Ratio Carbon Nanotube Membranes Decorated with Pt Nanoparticle Urchins for Micro Underwater Vehicle Propulsion via H2O2 Decomposition

The utility of unmanned micro underwater vehicles (MUVs) is paramount for exploring confined spaces, but their spatial agility is often impaired when maneuvers require burst-propulsion. Herein we develop high-aspect ratio (150:1), multiwalled carbon nanotube microarray membranes (CNT-MMs) for propulsive, MUV thrust generation by the decomposition of hydrogen peroxide (H2O2). The CNT-MMs are grown via chemical vapor deposition with diamond shaped pores (nominal diagonal dimensions of 4.5 × 9.0 μm) and subsequently decorated with urchin-like, platinum (Pt) nanoparticles via a facile, electroless, chemical deposition process. The Pt-CNT-MMs display robust, high catalytic ability with an effective activation energy of 26.96 kJ mol–1 capable of producing a thrust of 0.209 ± 0.049 N from 50% [w/w] H2O2 decomposition within a compact reaction chamber of eight Pt-CNT-MMs in series

Characterization of Particle Emissions and Fate of Nanomaterials During Incineration

As the use of nanotechnology in consumer products continues to grow, it is inevitable that some nanomaterials will end up in the waste stream and will be incinerated. Through laboratory-scale incineration of paper and plastic wastes containing nanomaterials, we assessed their effect on emissions of particulate matter (PM) and the effect of incineration on the nanomaterials themselves. The presence of nanomaterials did not significantly influence the particle number emission factor. The PM size distribution was not affected except at very high mass loadings (10 wt%) of the nanomaterial, in which case the PM shifted toward smaller sizes; such loadings are not expected to be present in many consumer products. Metal oxide nanomaterials reduced emissions of particle-bound polycyclic aromatic hydrocarbons. Most of the nanomaterials that remained in the bottom ash retained their original size and morphology but formed large aggregates. Only small amounts of the nanomaterials (0.023–180 mg g−1 of nanomaterial) partitioned into PM, and the emission factors of nanomaterials from an incinerator equipped with an electrostatic precipitator are expected to be low. However, a sustainable disposal method for nanomaterials in the bottom ash is needed, as a majority of them partitioned into this fraction and may thus end up in landfills upon disposal of the ash

Aerosol Microdroplets Exhibit a Stable pH Gradient

Suspended aqueous aerosol droplets (\u3c50 μm) are microreactors for many important atmospheric reactions. In droplets and other aquatic environments, pH is arguably the key parameter dictating chemical and biological processes. The nature of the droplet air/ water interface has the potential to significantly alter droplet pH relative to bulk water. Historically, it has been challenging to measure the pH of individual droplets because of their inaccessibility to conventional pH probes. In this study, we scanned droplets containing 4-mercaptobenzoic acid–functionalized gold nanoparticle pH nanoprobes by 2D and 3D laser confocal Raman microscopy. Using surface-enhanced Raman scattering, we acquired the pH distribution inside approximately 20-μm-diameter phosphate-buffered aerosol droplets and found that the pH in the core of a droplet is higher than that of bulk solution by up to 3.6 pH units. This finding suggests the accumulation of protons at the air/water interface and is consistent with recent thermodynamic model results. The existence of this pH shift was corroborated by the observation that a catalytic reaction that occurs only under basic conditions (i.e., dimerization of 4-aminothiophenol to produce dimercaptoazobenzene) occurs within the high pH core of a droplet, but not in bulk solution. Our nanoparticle probe enables pH quantification through the cross-section of an aerosol droplet, revealing a spatial gradient that has implications for acid-base–catalyzed atmospheric chemistry

Comparing large lecture mechanics curricula using the Force Concept Inventory: A five thousand student study

The performance of over 5000 students in introductory calculus-based mechanics courses at the Georgia Institute of Technology was assessed using the Force Concept Inventory (FCI). Results from two different curricula were compared: a traditional mechanics curriculum and the Matter & Interactions (M&I) curriculum. Post-instruction FCI averages were significantly higher for the traditional curriculum than for the M&I curriculum; the differences between curricula persist after accounting for factors such as pre-instruction FCI scores, grade point averages, and SAT scores. FCI performance on categories of items organized by concepts was also compared; traditional averages were significantly higher in each concept. We examined differences in student preparation between the curricula and found that the relative fraction of homework and lecture topics devoted to FCI force and motion concepts correlated with the observed performance differences. Limitations of concept inventories as instruments for evaluating curricular reforms are discussed.Comment: 21 pages, 4 figures, submitted to Am. J. Phys. arXiv admin note: substantial text overlap with arXiv:1112.559

An Empirical Explanation of the Speed-Distance Effect

Understanding motion perception continues to be the subject of much debate, a central challenge being to account for why the speeds and directions seen accord with neither the physical movements of objects nor their projected movements on the retina. Here we investigate the varied perceptions of speed that occur when stimuli moving across the retina traverse different projected distances (the speed-distance effect). By analyzing a database of moving objects projected onto an image plane we show that this phenomenology can be quantitatively accounted for by the frequency of occurrence of image speeds generated by perspective transformation. These results indicate that speed-distance effects are determined empirically from accumulated past experience with the relationship between image speeds and moving objects