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An extensive body of research using concurrent‐chains schedules of reinforcement has shown that choice for one of two differentially valued food‐associated stimuli is dependent upon the overall temporal context in which those stimuli are embedded. The present experiments examined whether the concurrent chains procedure was useful for the study of behavior maintained by alcohol and alcohol‐associated stimuli. In Experiment 1, rats responded on concurrent‐chains schedules with equal variable‐interval (VI) 10‐s schedules in the initial links. Across conditions, fixed‐interval schedules in the terminal links were varied to yield 1:1, 9:1, and 1:9 ratios of alcohol delivery. Initial‐link response rates reflected changes in terminal‐link schedules, with greater relative responding in the rich terminal link. In Experiment 2, terminal‐link schedules remained constant with a 9:1 ratio of alcohol delivery rates while the length of two equal duration initial‐link schedules was varied. Preference for the rich terminal link was less extreme when initial links were longer (i.e., the initial‐link effect), as has been previously reported with food reinforcers. This result suggests that the conditioned reinforcing value of an alcohol‐associated stimulus depends on the temporal context in which it is embedded. The concurrent‐chains procedure and quantitative models of concurrent chains performance may provide a useful framework within which to study how contextual variables modulate preference for drug‐associated conditioned reinforcers.

Impulsive stress in repeated shock waves administered during extracorporeal shock-wave lithotripsy (ESWL) causes injury to kidney tissue. In a study of the mechanical input of ESWL, the effects of focused shock waves on thin planar polymeric membranes immersed in a variety of tissue-mimicking fluids have been examined. A direct mechanism of failure by shock compression and an indirect mechanism by bubble collapse have been observed. Thin membranes are easily damaged by bubble collapse. After propagating through cavitation-free acoustically heterogeneous media (liquids mixed with hollow glass spheres, and tissue) shock waves cause membranes to fail in fatigue by a shearing mechanism. As is characteristic of dynamic fatigue, the failure stress increases with strain rate, determined by the amplitude and rise time of the attenuated shock wave. Shocks with large amplitude and short rise time (i.e., in uniform media) cause no damage. Thus the inhomogeneity of tissue is likely to contribute to injury in ESWL. A definition of dose is proposed which yields a criterion for damage based on measurable shock wave properties.

This edited volume examines the opportunities to think, do, and/or create jointly afforded by digital storytelling. The contributors discuss digital storytelling in the context of educational programs, teaching anthropology, and ethnographic research involving a variety of populations and subjects that will appeal to researchers and practitioners engaged with qualitative methods and pedagogies that rely on media technology.

The adenine nucleotide translocation in mitochondria has previously been established as an exchange between exogenous and endogenous adenine nucleotides across the inner membrane. The specificity and the control of the exchange are examined with the following major results: The adenine nucleotide translocation is relatively specific for exogenous ADP and ATP, AMP being nearly inactive. Among other nucleotides tested, only dADP and dATP exchange with a noticeable activity. In the controlled state ADP exchanges 2–4 times faster than ATP. If simultaneously added, ADP and ATP compete for the exchange, with ADP being about tenfold more active than ATP. The specificity of the exit of adenine nucleotides in the exchange is similar to the specificity of the entrance with the difference that ADP and ATP are released with equal activity in proportion to their intramitochondrial content. AMP is released only after a slow conversion to ADP. Therefore the short time exchange is limited by the endogenous content of ADP plus ATP. The exchange is influenced by the metabolic state of the mitochondria. The ATP exchange is more variable than the ADP exchange. Two effects are elucidated: (a) the influence of the metabolic state on the relative content of AMP which inhibits both the ADP and ATP exchange (b) the coupling of the energy transfer system which inhibits only the ATP exchange. An example for case (a) is the inhibition of the ADP and ATP exchange by arsenate and an example for case (b) is the strong increase of the ATP exchange on uncoupling. The following effects are relevant to the mechanism of the control of the exchange by ATP. The stimulation of the ATP exchange by uncoupler has the same concentration dependence as the uncoupling of oxidative phosphorylation (Km [CCP] = 0.08 μM, where CCP = carbonyl‐cyanide‐phenylhydrazone). Oligomycin does not abolish the uncoupler effect on the ATP exchange. “Endogenous uncoupling” on aging of mitochondria also stimulates the ATP exchange. Valinomycin plus K+ only slightly stimulate the ATP exchange. Anaerobiosis stimulates the ATP exchange to a smaller extent than uncoupling.In competition with ADP the effects of energy transfer on ATP exchange are more strongly revealed. On uncoupling the more than tenfold preference for ADP is fully abolished. It is concluded that basically the exchange for ADP and ATP has equal specificity in forward and reverse reaction. In the controlled state a superimposed force makes the specificity asymmetric and inhibits the entrance of ATP. This control of the ATP exchange is concluded to be based on the anionic character of the adenine nucleotides. Thus the ATP4‐ex–ADP3‐in exchange is inhibited unless the charge difference is compensated for by an uncoupler stimulated H+ movement across the membrane. Furthermore an electric potential gradient appears to be effective in the controlled state which is abolished on uncoupling.

Abstract The analysis and optimization of flat plate fins of constant thickness and straight base has been conducted for different fin’s shapes. Performance of the fins is quantified through effectiveness and expressed as a function of fin’s shape, width, and area. A linear piecewise function with varying number of evenly spaced sections is used to generate shapes with different number of degrees of freedom, which are classified as constrained- or unconstrained-base depending on the width of the fin at the constant temperature base location. For one- and two-degrees of freedom shapes, a variety of rectangular, triangular, trapezoidal, and rhomboidal geometries are considered and optimized. For more than two-degrees of freedom, more complex resulting shapes are also considered. By adjusting the value of the corresponding shape parameters, the best possible distributions of available area to maximize heat transfer are obtained, which produce significant improvements favored by smaller width and larger area. Unconstrained-base performs better than constrained-base configurations as they allow the distribution of a larger area close to the high-temperature base. Optimal shape of unconstrained-base fins is in general convergent with non-zero wide tip, while, for constrained-base fins, it is divergent in the first linear section from the base and convergent in the remaining ones. For increasing number of degrees of freedom the optimized shapes tend to resemble natural structures while effectiveness increases asymptotically to a limit for constant width and area. Besides determining the optimal configurations, consideration has been made about the optimal regions where a variety of shapes produce virtually the same effectiveness of the absolute maximum, which can be used to design fins with almost maximum performance but having simpler shapes or being functional under possible space restrictions. The dimensionless model and the systematic analysis proposed in this work are not only appropriate to study a wide range of flat plate fins but also can be implemented to analyze and perform optimization over other type of fins and fins configurations.

Abstract Levee systems are an important part of California’s water infrastructure, engineered to provide resilience against flooding and reduce flood losses. The growth in California is partly associated with costly infrastructure developments that led to population expansion in the levee protected areas. Therefore, potential changes in the flood hazard could have significant socioeconomic consequences over levee protected areas, especially in the face of a changing climate. In this study, we examine the possible impacts of a warming climate on flood hazard over levee protected land in California. We use gridded maximum daily runoff from global circulation models (GCMs) that represent a wide range of variability among the climate projections, and are recommended by the California’s Fourth Climate Change Assessment Report, to investigate possible climate-induced changes. We also quantify the exposure of several critical infrastructure protected by the levee systems (e.g. roads, electric power transmission lines, natural gas pipelines, petroleum pipelines, and railroads) to flooding. Our results provide a detailed picture of change in flood risk for different levees and the potential societal consequences (e.g. exposure of people and critical infrastructure). Levee systems in the northern part of the Central Valley and coastal counties of Southern California are likely to observe the highest increase in flood hazard relative to the past. The most evident change is projected for the northern region of the Central Valley, including Butte, Glenn, Yuba, Sutter, Sacramento, and San Joaquin counties. In the leveed regions of these counties, based on the model simulations of the future, the historical 100-year runoff can potentially increase up to threefold under RCP8.5. We argue that levee operation and maintenance along with emergency preparation plans should take into account the changes in frequencies and intensities of flood hazard in a changing climate to ensure safety of levee systems and their protected infrastructure.

Abstract Dimethyl ether appears to be a better choice among various diesel alternatives due to its high cetane number and sootless combustion. However, the physical and chemical properties of dimethyl ether are very different from those of diesel. The physical properties influence spray formation and atomization characteristics, while chemical properties determine combustion and emission formation characteristics. Thus, fuel's physical and chemical properties significantly determine engine performance and emissions. In the present work, spray combustion and emission formation characteristics of n-heptane, dimethyl ether, and their blends (10, 25, and 50% dimethyl ether in n-heptane) were numerically studied in a constant volume chamber. Results show that the n-heptane spray combustion has the highest heat release rate with an intense premix combustion phase, whereas dimethyl ether spray combustion has the lowest heat release rate and shortest premix combustion phase. The magnitude of the premixed phase and heat release rate decreases with the increase in dimethyl ether mass fraction in the blends. Soot, carbon monoxide (CO), unburned hydrocarbon (UHC), and nitric oxide (NO) emissions decreased with the increase in the dimethyl ether mass fraction in the blends and were lowest for the dimethyl ether.