Alpha- and beta-adrenergic mediation of changes in metabolism and Na/K exchange in rat brown fat

Double- and triple-barreled ion-sensitive microelectrodes were used to measure changes in extracellular K+ and Na+ concentrations ([K+]o, [Na+]o) in brown fat. Redox states of different respiratory enzymes were measured simultaneously in order to correlate ion movements with metabolic activity. Trains of stimuli applied to the efferent nerves evoked two distinct increases in [K+]o. A first, small, rapid increase occurred within 10 s and accompanied a first, rapid membrane depolarization. A second, slow increase of [K+]o occurred several minutes after stimulation and accompanied a second, slow depolarization. A few seconds after stimulation onset, while the membrane was repolarizing and shifts in redox states indicated increases in lipolysis and respiration, [K+]o decreased. The [K+]o decrease was accompanied by an increase in [Na+]o, and could be partly blocked by ouabain. Phentolamine, an alpha-antagonist that blocks the first depolarization, also blocked the first, rapid [K+]o increase and part of the subsequent decrease. Propranolol, a beta-antagonist, had little effect on the first depolarization and the first increase in [K+]o, but blocked part of the subsequent [K+]o decrease and the second, slow [K+]o increase. The changes in [K+]o were almost completely abolished in the presence of both antagonists. It is concluded that brown adipocytes take up K+ and simultaneously lose Na+ in response to the interaction of noradrenaline with alpha- and beta-receptors, and this indicates a very early stimulation of the Na+ pump

The \u27Flattened\u27 Projections of Orientable Surfaces

When orientable surfaces having at least one edge are immersed into the plane, there often exists regions where two parts of the surface must occupy the same space in the plane. If these regions are considered overlaps rather than intersections, the surface remains embedded in three-space but appears to be flattened. This form of the surface, called a flattening, can be subjected to certain deformations without leaving its flattened state. Called flat deformations, these deformations can be used to show that two apparently different flattenings are sometimes just two forms of the same flattening; in that case, the two original forms are called indistinct. This paper attempts to determine a formula relating the properties of a given surface with the number of distinct flattenings which can possibly be formed from it. Specifically, it focuses on the flattenings of tori with n disks removed. Although an explicit formula is not derived, the paper outlines a method for determining the correct number of flattenings, and charts this number against n for values up to ten

The Effect of Daily Progress Reports on Parental Academic Support: Paper versus Electronic Communication

In this age of data based decision making and accountability, parent involvement and data collection are paramount. This study represents a significant contribution to educational research by extending the understanding of home-school communication media with specific regard to daily progress reports. The purpose of this study was to compare communication scores of parents of student using paper daily progress reports with communication scores of parents of student using electronic daily progress reports. This quasi-experimental posttest only control group design research study compared survey results of parents (N = 45) of middle school students currently using a DPR as part of an intervention in a middle school located in central Connecticut. The survey instrument was the Parental Academic Support Scale (PASS) containing five subscales: Academic Performance, Classroom Behavior, Preparation, Hostile Peer Interactions, and Health. Independent t tests were conducted to discover whether the mean communication scores between groups of parents were significantly different. A chi-square (χ2) analysis was conducted to evaluate difference in media preference between groups. Significant differences in communication practices and preferences were found. Parents of children using electronic daily progress reports practiced more regular communication with teachers. Likewise, parent media preferences were significantly different between groups. Recommendations for further research are discussed

Electrochemical impedance spectroscopy for the study of catalysis and electrode degradation in vanadium redox-flow batteries

Vanadium redox-flow batteries (VRFBs) are emerging as promising systems for large-scale energy storage. Yet, certain key aspects require for substantial improvements in order to achieve broad commercial success of this technology. In that respect, further development of electrode materials in terms of increased and durable electrocatalytic activity is of essence, especially in the negative half cell. Myriads of approaches for surface modification of the predominantly employed macroporous carbons have thus been proposed so far. However, upon thorough review of pre-existing literature, it became evident that meaningfully benchmarking and quantifying the effects of those procedures with regard to resulting performance enhancement is anything but a straightforward task. The emphasis of this thesis was therefore put on establishing methodical approaches for reliable and unambiguous quantification of electrode kinetics by properly utilizing electrochemical techniques, predominantly electrochemical impedance spectroscopy (EIS), and exploiting their full capabilities. In an exemplary study on bismuth-modified carbon felt electrodes it was demonstrated how applying proper normalization to ex-situ impedance data enables thorough characterization and standardized comparison of electrocatalytic effects induced by incorporation of metal (oxide) particles or any other type of supposedly activating treatment. Intrinsic catalytic activity of Bi for the V(II)/V(III) redox reaction has been verified and stability of modified electrodes was assessed for the first time. By eliminating the often misleading impact of electrode wetting, reproducibility of obtained results was greatly enhanced compared to other approaches commonly pursued in the open literature. Subsequently, the innovative concept of distribution of relaxation times (DRT) analysis was introduced to the field of in-situ examination of VRFB cells. Loss processes during operation of the battery have been unraveled before proving the feasibility of DRT-based monitoring of electrode ageing. Gained insights underline the importance of keeping future research focused on the negative half cell electrode, at least in terms of electrocatalysis and degradation. Further investigations explored how synergistic use of additional techniques may complement the experimental capabilities of EIS to determine electrode characteristics in the most comprehensive way. This involved unequivocal separation of respective current contributions from V(III) -reduction and parasitic hydrogen evolution reaction (HER) at planar model electrodes during rotating ring-disc electrode (RRDE) and alternating current cyclic voltammetry (ACCV) measurements as well as visualization of bismuth dissolution and redeposition in an operating VRFB by utilization of X-ray-based imaging procedures

Universal Algorithm for Simulating and Evaluating Cyclic Voltammetry at Macroporous Electrodes by Considering Random Arrays of Microelectrodes

An algorithm for the simulation and evaluation of cyclic voltammetry (CV) at macroporous electrodes such as felts, foams, and layered structures is presented. By considering 1D, 2D, and 3D arrays of electrode sheets, cylindrical microelectrodes, hollow‐cylindrical microelectrodes, and hollowspherical microelectrodes the internal diffusion domains of the macroporous structures are approximated. A universal algorithm providing the timedependent surface concentrations of the electrochemically active species, required for simulating cyclic voltammetry responses of the individual planar, cylindrical, and spherical microelectrodes, is presented as well. An essential ingredient of the algorithm, which is based on Laplace integral transformation techniques, is the use of a modified Talbot contour for the inverse Laplace transformation. It is demonstrated that first‐order homogeneous chemical kinetics preceding and/or following the electrochemical reaction and electrochemically active species with non‐equal diffusion coefficients can be included in all diffusion models as well. The proposed theory is supported by experimental data acquired for a reference reaction, the oxidation of [Fe(CN)6]4− at platinum electrodes as well as for a technically relevant reaction, the oxidation of VO2+ at carbon felt electrodes. Based on our calculation strategy, we provide a powerful open source tool for simulating and evaluating CV data implemented into a Python graphical user interface (GUI)

Forestry Cooperatives for Diverse Management Goals: An Assessment of Interest Levels among Maine\u27s Nonindustrial Private Forest Owners Enrolled in the Tree Growth Tax Program

Owners of small, non-industrial woodland parcels in the United States maintain heterogeneous management goals for their individual parcels. Research has shown that timber harvesting is becoming less of a priority for this landowner group. In addition, average parcel size for these ownerships has decreased noticeably over the past 20 years. Parcelization, forest fragmentation and the presence of varied landowner goals complicate the matter of conducting ecologically sound, financially feasible forest management. The purpose of this study was to present thee forestry cooperative models to small, non-industrial woodland owners in Maine and to ascertain interest levels. Cooperative models were based on existing organizations have been designed to facilitate ecologically sensitive forest management. The cooperatives are focused on endorsing active timber production in an ecological context while addressing the multitude of landowner objectives. A survey was sent to 1500 landowners in the organized townships of Maine with a response rate of 3 1.3 percent (470 total useable returns). Questions were designed to explore landowner management priorities, landowner satisfaction with their current management regime, and interest in the three cooperative models. Chisquare analysis was used and logistic regression models were created to test the impact of various landowner characteristics on interest in the three cooperatives. Of the three models, landowner interest was highest for the Network , followed by the Marketing Cooperative . Least popular was the Woods Bank in which landowners relinquish property rights for an annual dividend based on the fair market value of their land. Interest in cooperatives in general was positively correlated with the desire to protect nature and biological diversity, an interest in cooperation for the purposes of ecosystem management, the desire to collectively own wood processing facilities for the purposes of retaining more of the value-added from wood harvested, and a long planning horizon for recreation activities. Some differences were evident regarding interest in the three individual cooperative organizations

Risk Preference, Time Preference, and Salience Perception

A model of decision making is introduced that provides a unified approach for predicting choices under risk and over time. The model predicts systematic departures from expected utility and discounted utility using the same mathematical structure and the same psychological intuition and shows that a dozen diverse choice anomalies can be given a common underlying explanation. The model weights attribute differences both by their importance (consistent with expected utility and discounted utility) and by their salience or similarity (consistent with procedural models based on heuristics), and so provides a bridge between rational and heuristic representations of decision making

A Theory of Focal Points in 2x2 Games

Since the classic work of Schelling, the notion of a focal point has been widely applied to explain coordinated behavior. However, focal points remain largely outside the formal apparatus of game theory. This paper develops a model of play in 2 × 2 games where payoff differences determine what strategy players will perceive as “salient” and choose to play. The model uniquely predicts which outcome will emerge for virtually the entire class of 2 × 2 normal form games. For the subset of such games involving coordination and asymmetric payoffs, payoff differences identify focal outcomes and strategies in the same way shared social knowledge produces coordination in Schelling’s symmetric games. The model characterizes situations when Nash equilibria are likely to be played, even in a one-shot interaction, and predicts which equilibrium will obtain in games containing more than one. It identifies other circumstances in which a non-equilibrium outcome will predominate. Finally, the theory specifies when a player is likely to select a strategy based solely on consideration of her own payoffs, and when and why the same player will be prompted to act strategically. Experimental results are presented that test the predictions of the model