Cessation of Nightly Voluntary Wheel Running Activity Following Exposure to a Mouse Model of Posttraumatic Stress

Regular physical activity (PA) is well known to positively impact physical and mental health outcomes. In our work to examine cardiovascular benefits of PA in a mouse model of posttraumatic stress, we stumbled upon the reciprocal relationship between PA and stress exposure, wherein stress significantly reduced healthy levels of routine PA. The aim of the present studies was to define the parameters of our paradigm. C67BL/6J male mice were divided into four groups (n=8/group): sedentary/control, voluntary running/control, sedentary/stress, and voluntary running/stress. Voluntary running groups were given unlimited access to a running wheel for 9 weeks. Stress groups were then exposed to a 5-day resident-intruder social stress that models human posttraumatic stress. Running behavior essentially ceased following stress. Habituation to stress occurred, as running distance increased by the 5th day of stress but remained significantly low. A separate study examined a single exposure to resident-intruder social stress. Plasma corticosterone significantly increased while nightly running dropped significantly but returned to normal by the 3rd night post-stress. These studies show the sensitivity of habitual running behavior to stress exposure and suggest the utility of this mouse model in exploring the means by which stress negatively impacts routine PA

Metal-Insulator Transition Tuned by External Gates in Hall Systems with Constrictions

The nature of a metal-insulator transition tuned by external gates in quantum Hall (QH) systems with point constrictions, as reported in recent experiments of Roddaro et al [1], is examined. We attribute this phenomenon to a splitting of the integer edge into conducting and insulating stripes, the latter wide enough to allow for the stability of the edge structure. Inter-channel impurity scattering and inter-channel Coulomb interactions do not destabilize this picture.Comment: 4 pages, 6 figure

Cannabinoid Receptor Involvement in Stress-Induced Cocaine Reinstatement: Potential Interaction with Noradrenergic Pathways

This study examined the role of endocannabinoid signaling in stress-induced reinstatement of cocaine seeking and explored the interaction between noradrenergic and endocannabinergic systems in the process. A well-validated preclinical model for human relapse, the rodent conditioned place preference assay, was used. Cocaine-induced place preference was established in C57BL/6 mice using injections of 15 mg/kg cocaine. Following extinction of preference for the cocaine-paired environment, reinstatement of place preference was determined following 6 min of swim stress or cocaine injection (15 mg/kg, i.p.). The role of endocannabinoid signaling was studied using the cannabinoid antagonist AM-251 (3 mg/kg, i.p.). Another cohort of mice was tested for reinstatement following administration of the cannabinoid agonist CP 55,940 (10, 20, or 40 μg/kg, i.p.). The alpha-2 adrenergic antagonist BRL-44408 (5 mg/kg, i.p.) with or without CP 55,940 (20 μg/kg) was administered to a third group of mice. We found that: (1) AM-251 blocked forced swim-induced, but not cocaine-induced, reinstatement of cocaine-seeking behavior; (2) the cannabinoid agonist CP 55,940 did not reinstate cocaine-seeking behavior when administered alone but did synergize with a non-reinstating dose of the alpha-2 adrenergic antagonist BRL-44408 to cause reinstatement. These results are consistent with the hypothesis that stress exposure triggers the endogenous activation of CB1 receptors and that activation of the endocannabinoid system is required for the stress-induced relapse of the mice to cocaine seeking. Further, the data suggest that the endocannabinoid system interacts with noradrenergic mechanisms to influence stress-induced reinstatement of cocaine-seeking behavior

When is open-endedness desirable in restoration projects?

A low-intervention approach to restoration that also allows restoration outcomes to be framed as trajectories of ecosystem change can be described as ‘open-ended’ restoration. It is an approach that recognizes that long-term ecosystem behavior involves continual change at small and large spatial and temporal scales. There are a number of situations in which it is appropriate to adopt an open-ended approach to restoration including: in remote and large areas; where ecological limiting factors will be changed by future climates; where antecedent conditions cannot be replicated; where there are novel starting points for restoration; where restoration relies strongly on processes outside the restoration area; in inherently dynamic systems; where costs are high and where the public demands ‘wildness’. Where this approach is adopted managers need to explain the project and deal with public expectations and public risk. Monitoring biotic and abiotic components of the project are very important as an open-ended approach does not equate to ‘abandon and ignore it’

Variability of Cu 2 ZnSnS 4 nanoparticle hot injection synthesis and modifications by thin film annealing

As a quaternary semiconductor with a direct energy bandgap of around 1.4 eV, Cu2ZnSnS4 is a promising candidate for absorber layers in next generation thin-film solar PV devices. It has the advantage of being based on low cost earth-abundant elements. Solution based synthesis approaches show the greatest potential for scaling up manufacture. Cu2ZnSnS4 devices are currently limited in efficiency because of a large open circuit voltage deficit, arising predominantly from high concentrations of point defects and charge compensation defect complexes. To drive device efficiency robust, reliable and reproducible synthesis protocols are required. We have produced a series of Cu2ZnSnS4 thin films by spin coating nanoparticle ink suspensions fabricated under nominally identical conditions to investigate the inherent variability in hot injection synthesis of Cu2ZnSnS4 nanoparticles by fabricating 11 batches using the same initial conditions. We use two different chemical routes to extratct nanoparticles from solution after synthesis. We find that the lattice constants of the nanocrystalline material do not change significantly. The relative concentration of the constituent elements varies with S having the largest anion variation of ±3.8% as compared to metal cation variations of Zn ±2.4%, Cu ±1.8%, and Sn ±1.4% with Zn having the largest cation variation. We compare data from energy dispersive X-ray (EDX) and inductively coupled plasma mass spectroscopy (ICPMS) chemical analysis methods and find that the ICPMS analysis has a consistently smaller standard deviation, an average of 0.1 lower, as this technique samples a large volume of material. We observe variation in the kesterite tetragonal lattice constants a and c, and energy bandgap Eg across the different samples, although there is no systematic change in the chemical composition. The average bandgap of as-synthesised films is 1.14 eV. We find that annealing in a sulphur rich environment has no systematic impact on the Cu/(Zn + Sn) cation ratio and leads to a decrease of −0.4 in the Zn/Sn ratio. At higher annealing temperatures, 500–600 °C, the bandgap shows a linear increase of +0.15 eV accompanied by the formation of abnormal grains and an increase in the size of the crystalline scattering domain τ, determined from the X-ray spectra, from 30–100 nm. The most dramatic changes occur in the first 0.5 hours of annealing. These findings will help in the design of fabrication strategies for higher efficiency Cu2ZnSnS4 photovoltaic devices

Imaging morphological details and pathological differences of red blood cells using tapping-mode AFM

The surface topography of red blood cells (RBCs) was investigated under nearphysiological conditions using atomic force microscopy (AFM). An immobilization protocol was established where RBCs are coupled via molecular bonds of the membrane glycoproteins to wheat germ agglutinin (WGA), which is covalently and flexibly tethered to the support. This results in a tight but noninvasive attachment of the cells. Using tappingmode AFM, which is known as gentle imaging mode and therefore most appropriate for soft biological samples like erythrocytes, it was possible to resolve membrane skeleton structures without major distortions or deformations of the cell surface. Significant differences in the morphology of RBCs from healthy humans and patients with systemic lupus erythematosus (SLE) were observed on topographical images. The surface of RBCs from SLE patients showed characteristic circularshaped holes with approx. 200 nm in diameter under physiological conditions, a possible morphological correlate to previously published changes in the SLE erythrocyte membrane

Tactical design of last mile logistical systems

Tactical Design of Last Mile Logistical Systems Alexander M. Stroh 161 Pages Directed by Dr. Alan Erera and Dr. Alejandro Toriello This dissertation consists of three distinct logistical topics, unified by a focus on the intelligent design of last mile logistical systems at a tactical level. The three design problems all arise within package delivery supply chains, though the mathematical models and solution techniques developed in these studies can be applied to other logistics systems. We propose models that do not attempt to capture granular minute by minute operational decision making, but rather, system behavior on average so that we may approximate the impact of various design choices. In Chapter 2, we study tactical models for the design of same-day delivery (SDD) systems. While previous literature includes operational models to study SDD, they tend to be detailed, complex, and computationally difficult to solve. Thus, such models may not provide any insight into tactical SDD design variables and their impact on the average performance of the system. We propose a simplified vehicle dispatching model that captures the average behavior of an SDD system from a single depot location by utilizing continuous approximation techniques. We analyze the structure of vehicle dispatching policies given by our model for various families of problem instances and develop techniques to find optimal dispatching policies that require only simple computations. Our models can help answer various tactical design questions including how to select a fleet size, determine an order cutoff time, and combine SDD and overnight order delivery operations. In Chapter 3, we study the tactical optimization of SDD systems under the assumption that service regions are allowed to vary over the course of each day. In most existing studies of last mile logistics problems, service regions are assumed to be static. Service regions which are designed too small or cutoff SDD availability too soon may potentially lose SDD market share, while regions which are designed too large or accept orders too late may result in costly operations or failed deliveries, resulting in a loss of customer goodwill. We use a continuous approximation approach to capture average system behavior and derive optimal dynamic service region areas and tactical vehicle dispatching policies which maximize the expected number of SDD orders served per day. Furthermore, we compare such designs to fixed service region designs or capacitated service region designs. In Chapter 4, we introduce the concept of cycle time considering capacitated vehicle routing problems, which are motivated by the desire to decrease the average time packages spent within a delivery network. Traditional vehicle routing models focus on the resource usage of the system whereas our models instead consider the impact of routing policies on the units being served. We explicitly consider pre-routing waiting times at a depot, total demand-weighted accumulated routing times, vehicle capacity constraints, and designing repeatable delivery routes in our models. We present two set partitioning formulations for such problems and derive efficient solution techniques so that the impact of various design parameters can be assessed.Ph.D