Elevated Outcome-Anticipation and Outcome-Evaluation ERPs Associated with a Greater Preference for Larger-But-Delayed Rewards

PubMed Central

Pornpattananangkul, Narun; Nadig, Ajay; Heidinger, Storm; Walden, Keegan; Nusslock, Robin

2017-01-01

Although waiting for a reward reduces or discounts its value, some people have a stronger tendency to wait for larger rewards and forgo smaller-but-immediate rewards. This ability to delay gratification is captured by individual differences in so-called inter-temporal choices in which individuals are asked to choose between larger-but-delayed versus smaller-but-immediate rewards. The current study used event-related potentials (ERPs) to examine whether enhancement in two neuro-cognitive processes, outcome-anticipation and outcome-evaluation, modulate individual variability in inter-temporal responses. After completing a behavioral inter-temporal choice task, 34 participants performed an ERP gambling task. From this ERP task, we separately examined individual differences in outcome-anticipation (Stimulus-Preceding Negativity, SPN), early outcome-evaluation (Feedback-Related Negativity; FRN) and late outcome-evaluation (P3). We observed that both elevated outcome-anticipation (SPN) and late outcome-evaluation (P3) neural processes predicted a stronger preference toward larger-but-delayed rewards. No relationship was observed between inter-temporal responses and early outcome-evaluation (FRN), indicating that the relationship between outcome-evaluation and inter-temporal responses was specific to the late outcome-evaluation processing stream. Moreover, multiple regression analyses indicated that the SPN and P3 independently modulate individual differences in inter-temporal responses, suggesting separate mechanisms underlie the relationship between these two neuro-cognitive processes and inter-temporal responses. Accordingly, we identify two potential neural-cognitive modulators of individual variability in inter-temporal responses. We discuss the mechanisms underlying these modulators in terms of anticipation-related processing (SPN) and a saliency-bias toward gain (compared to loss) outcomes (P3). PMID:28224457

Money Earlier or Later? Simple Heuristics Explain Intertemporal Choices Better than Delay Discounting1

PubMed Central

Marzilli Ericson, Keith M.; White, John Myles; Laibson, David; Cohen, Jonathan D.

2015-01-01

Heuristic models have been proposed for many domains of choice. We compare heuristic models of intertemporal choice, which can account for many of the known intertemporal choice anomalies, to discounting models. We conduct an out-of-sample, cross-validated comparison of intertemporal choice models. Heuristic models outperform traditional utility discounting models, including models of exponential and hyperbolic discounting. The best performing models predict choices by using a weighted average of absolute differences and relative (percentage) differences of the attributes of the goods in a choice set. We conclude that heuristic models explain time-money tradeoff choices in experiments better than utility discounting models. PMID:25911124

Testing the effect of risk on intertemporal choice in the Chinese cultural context.

PubMed

Sun, Yan; Li, Shu

2011-01-01

Previous studies using Western samples have found that introducing uncertainty to an intertemporal choice decreases the degree of discounting future rewards. The authors of this article examined the effect of risk on intertemporal choice using Chinese participants and found that respondents preferred the smaller but sooner (SS) outcome to the larger but later (LL) one in the presence of risk, which indicates that risk increases rather than decreases the degree of discounting future rewards. Thus, variations in response patterns between different cultural groups suggest that culture may play an important role in intertemporal choice and researchers should delve into this topic from an emic rather than an etic perspective.

Now or not-now? The influence of alexithymia on intertemporal decision-making.

PubMed

Scarpazza, Cristina; Sellitto, Manuela; di Pellegrino, Giuseppe

2017-06-01

Optimal intertemporal decisions arise from the balance between an emotional-visceral component, signaling the need for immediate gratification, and a rational, long-term oriented component. Alexithymia, a personality construct characterized by amplified sensitivity to internal bodily signals of arousal, may result in enhanced activation of the emotional-visceral component over the cognitive-rational one. To test this hypothesis, participants with high- and low-alexithymia level were compared at an intertemporal decision-making task, and their choice behavior correlated with their interoceptive sensitivity. We show that high-alexithymic tend to behave more impatiently than low-alexithymic in intertemporal decisions, particularly when the sooner reward is immediately available. Moreover, the greater their sensitivity to their own visceral sensations, the greater the impatience. Together, these results suggest a disproportionate valuation of reward available immediately in high alexithymia, possibly reflecting heightened perception of bodily physiological signals, which ultimately would bias their intertemporal decision-making. Copyright © 2017 Elsevier Inc. All rights reserved.

What Do I Want and When Do I Want It: Brain Correlates of Decisions Made for Self and Other

PubMed Central

Albrecht, Konstanze; Volz, Kirsten G.; Sutter, Matthias; von Cramon, D. Yves

2013-01-01

A number of recent functional Magnetic Resonance Imaging (fMRI) studies on intertemporal choice behavior have demonstrated that so-called emotion- and reward-related brain areas are preferentially activated by decisions involving immediately available (but smaller) rewards as compared to (larger) delayed rewards. This pattern of activation was not seen, however, when intertemporal choices were made for another (unknown) individual, which speaks to that activation having been triggered by self-relatedness. In the present fMRI study, we investigated the brain correlates of individuals who passively observed intertemporal choices being made either for themselves or for an unknown person. We found higher activation within the ventral striatum, medial prefrontal and orbitofrontal cortex, pregenual anterior cingulate cortex, and posterior cingulate cortex when an immediate reward was possible for the observer herself, which is in line with findings from studies in which individuals actively chose immediately available rewards. Additionally, activation in the dorsal anterior cingulate cortex, posterior cingulate cortex, and precuneus was higher for choices that included immediate options than for choices that offered only delayed options, irrespective of who was to be the beneficiary. These results indicate that (1) the activations found in active intertemporal decision making are also present when the same decisions are merely observed, thus supporting the assumption that a robust brain network is engaged in immediate gratification; and (2) with immediate rewards, certain brain areas are activated irrespective of whether the observer or another person is the beneficiary of a decision, suggesting that immediacy plays a more general role for neural activation. An explorative analysis of participants’ brain activation corresponding to chosen rewards, further indicates that activation in the aforementioned brain areas depends on the mere presence, availability, or actual reception of immediate rewards. PMID:23991196

A Probabilistic, Dynamic, and Attribute-wise Model of Intertemporal Choice

PubMed Central

Dai, Junyi; Busemeyer, Jerome R.

2014-01-01

Most theoretical and empirical research on intertemporal choice assumes a deterministic and static perspective, leading to the widely adopted delay discounting models. As a form of preferential choice, however, intertemporal choice may be generated by a stochastic process that requires some deliberation time to reach a decision. We conducted three experiments to investigate how choice and decision time varied as a function of manipulations designed to examine the delay duration effect, the common difference effect, and the magnitude effect in intertemporal choice. The results, especially those associated with the delay duration effect, challenged the traditional deterministic and static view and called for alternative approaches. Consequently, various static or dynamic stochastic choice models were explored and fit to the choice data, including alternative-wise models derived from the traditional exponential or hyperbolic discount function and attribute-wise models built upon comparisons of direct or relative differences in money and delay. Furthermore, for the first time, dynamic diffusion models, such as those based on decision field theory, were also fit to the choice and response time data simultaneously. The results revealed that the attribute-wise diffusion model with direct differences, power transformations of objective value and time, and varied diffusion parameter performed the best and could account for all three intertemporal effects. In addition, the empirical relationship between choice proportions and response times was consistent with the prediction of diffusion models and thus favored a stochastic choice process for intertemporal choice that requires some deliberation time to make a decision. PMID:24635188

Common neural correlates of intertemporal choices and intelligence in adolescents.

PubMed

Ripke, Stephan; Hübner, Thomas; Mennigen, Eva; Müller, Kathrin U; Li, Shu-Chen; Smolka, Michael N

2015-02-01

Converging behavioral evidence indicates that temporal discounting, measured by intertemporal choice tasks, is inversely related to intelligence. At the neural level, the parieto-frontal network is pivotal for complex, higher-order cognitive processes. Relatedly, underrecruitment of the pFC during a working memory task has been found to be associated with steeper temporal discounting. Furthermore, this network has also been shown to be related to the consistency of intertemporal choices. Here we report an fMRI study that directly investigated the association of neural correlates of intertemporal choice behavior with intelligence in an adolescent sample (n = 206; age 13.7-15.5 years). After identifying brain regions where the BOLD response during intertemporal choice was correlated with individual differences in intelligence, we further tested whether BOLD responses in these areas would mediate the associations between intelligence, the discounting rate, and choice consistency. We found positive correlations between BOLD response in a value-independent decision network (i.e., dorsolateral pFC, precuneus, and occipital areas) and intelligence. Furthermore, BOLD response in a value-dependent decision network (i.e., perigenual ACC, inferior frontal gyrus, ventromedial pFC, ventral striatum) was positively correlated with intelligence. The mediation analysis revealed that BOLD responses in the value-independent network mediated the association between intelligence and choice consistency, whereas BOLD responses in the value-dependent network mediated the association between intelligence and the discounting rate. In summary, our findings provide evidence for common neural correlates of intertemporal choice and intelligence, possibly linked by valuation as well as executive functions.

Developmental trends and individual differences in brain systems involved in intertemporal choice during adolescence.

PubMed

Banich, Marie T; De La Vega, Alejandro; Andrews-Hanna, Jessica R; Mackiewicz Seghete, Kristen; Du, Yiping; Claus, Eric D

2013-06-01

This study used functional magnetic resonance imaging (fMRI) to examine the neural systems activated during an intertemporal choice task in a group of 14- to 19-year-old adolescents, as well as the relationship of such activation patterns to individual differences in the self-reported ability to engage in nonimmediate thinking (i.e., less impulsive and more future-oriented thoughts and action). With increasing age, there was greater differentiation between patterns of brain activity for immediate versus future choices across three distinct brain systems involved in intertemporal choice--those involved in exerting control over behavior, attributing affective value to choices, and imagining future outcomes. Furthermore, a greater propensity toward self-reported nonimmediate thinking was associated with decreased activity in the systems involved in cognitive control, possibly suggesting that individuals with greater self-reported nonimmediate thinking need to rely less on cognitive control regions during conditions of intertemporal choice. These results highlight the role that both developmental age and individual differences play in influencing neural systems involved in intertemporal choice. Implications for understanding the onset of substance abuse disorders during adolescence are discussed. 2013 APA, all rights reserved

A rational eating model of binges, diets and obesity.

PubMed

Dragone, Davide

2009-07-01

This paper addresses the rapid diffusion of obesity and the existence of different individual patterns of food consumption between non-dieters and chronic dieters. I propose a rational eating model where a forward-looking agent optimizes the intertemporal satisfaction from eating, taking into account the cost of changing consumption habits and the negative health consequences of having a non-optimal body weight. Consistent with the evidence, I show that the intertemporal maximization problem leads to a condition of overweightness, and that heterogeneity in the individual relevance of habits in consumption can determine the observed differences in the individual intertemporal patterns of food consumption and body weight. Sufficient conditions for determining when the convergence to the steady state implies oscillations or is monotonic are given. In the former case, the agent optimally alternates diets and binges until the steady state is reached, in the latter a regular intertemporal pattern of food consumption is optimal.

Intertemporal choice in lemurs.

PubMed

Stevens, Jeffrey R; Mühlhoff, Nelly

2012-02-01

Different species vary in their ability to wait for delayed rewards in intertemporal choice tasks. Models of rate maximization account for part of this variation, but other factors such as social structure and feeding ecology seem to underly some species differences. Though studies have evaluated intertemporal choice in several primate species, including Old World monkeys, New World monkeys, and apes, prosimians have not been tested. This study investigated intertemporal choices in three species of lemur (black-and-white ruffed lemurs, Varecia variegata, red ruffed lemurs, Varecia rubra, and black lemurs, Eulemur macaco) to assess how they compare to other primate species and whether their choices are consistent with rate maximization. We offered lemurs a choice between two food items available immediately and six food items available after a delay. We found that by adjusting the delay to the larger reward, the lemurs were indifferent between the two options at a mean delay of 17 s, ranging from 9 to 25 s. These data are comparable to data collected from common marmosets (Callithrix jacchus). The lemur data were not consistent with models of rate maximization. The addition of lemurs to the list of species tested in these tasks will help uncover the role of life history and socio-ecological factors influencing intertemporal choices. Copyright © 2011 Elsevier B.V. All rights reserved.

Spatial and intertemporal arbitrage in the California natural gas transportation and storage network

NASA Astrophysics Data System (ADS)

Uria Martinez, Rocio

Intertemporal and spatial price differentials should provide the necessary signals to allocate a commodity efficiently inside a network. This dissertation investigates the extent to which decisions in the California natural gas transportation and storage system are taken with an eye on arbitrage opportunities. Daily data about flows into and out of storage facilities in California over 2002-2006 and daily spreads on the NYMEX futures market are used to investigate whether the injection profile is consistent with the "supply-of-storage" curve first observed by Working for wheat. Spatial price differentials between California and producing regions fluctuate throughout the year, even though spot prices at trading hubs across North America are highly correlated. In an analysis of "residual supply", gas volumes directed to California are examined for the influence of those fluctuations in locational differentials. Daily storage decisions in California do seem to be influenced by a daily price signal that combines the intertemporal spread and the locational basis between California and the Henry Hub, in addition to strong seasonal and weekly cycles. The timing and magnitude of the response differs across storage facilities depending on the regulatory requirements they face and the type of customers they serve. In contrast, deviations in spatial price differentials from the levels dictated by relative seasonality in California versus competing regions do not trigger significant reallocations of flows into California. Available data for estimation of both the supply-of-storage and residual-supply curves aggregate the behavior of many individuals whose motivations and attentiveness to prices vary. The resulting inventory and flow profiles differ from those that a social planner would choose to minimize operating costs throughout the network. Such optimal allocation is deduced from a quadratic programming model, calibrated to 2004-2005, that acknowledges relative seasonality in demand, trade-offs between transportation and storage costs, infrastructure configuration and regulatory requirements. A comparison of the simulated equilibrium with observed behavior identifies where the arbitrage opportunities lie. Moreover, scenario analysis of such as a LNG terminal or additional storage capacity in California reveals the considerable indirect network effects brought about by changes at any node or arc.

Emotional arousal and discount rate in intertemporal choice are reference dependent.

PubMed

Lempert, Karolina M; Glimcher, Paul W; Phelps, Elizabeth A

2015-04-01

Many decisions involve weighing immediate gratification against future consequences. In such intertemporal choices, people often choose smaller, immediate rewards over larger delayed rewards. It has been proposed that emotional responses to immediate rewards lead us to choose them at our long-term expense. Here we utilize an objective measure of emotional arousal-pupil dilation-to examine the role of emotion in these decisions. We show that emotional arousal responses, as well as choices, in intertemporal choice tasks are reference-dependent and reflect the decision-maker's recent history of offers. Arousal increases when less predictable rewards are better than expected, whether those rewards are immediate or delayed. Furthermore, when immediate rewards are less predictable than delayed rewards, participants tend to be patient. When delayed rewards are less predictable, immediate rewards are preferred. Our findings suggest that we can encourage people to be more patient by changing the context in which intertemporal choices are made. (c) 2015 APA, all rights reserved).

The Attraction Effect Modulates Reward Prediction Errors and Intertemporal Choices.

PubMed

Gluth, Sebastian; Hotaling, Jared M; Rieskamp, Jörg

2017-01-11

Classical economic theory contends that the utility of a choice option should be independent of other options. This view is challenged by the attraction effect, in which the relative preference between two options is altered by the addition of a third, asymmetrically dominated option. Here, we leveraged the attraction effect in the context of intertemporal choices to test whether both decisions and reward prediction errors (RPE) in the absence of choice violate the independence of irrelevant alternatives principle. We first demonstrate that intertemporal decision making is prone to the attraction effect in humans. In an independent group of participants, we then investigated how this affects the neural and behavioral valuation of outcomes using a novel intertemporal lottery task and fMRI. Participants' behavioral responses (i.e., satisfaction ratings) were modulated systematically by the attraction effect and this modulation was correlated across participants with the respective change of the RPE signal in the nucleus accumbens. Furthermore, we show that, because exponential and hyperbolic discounting models are unable to account for the attraction effect, recently proposed sequential sampling models might be more appropriate to describe intertemporal choices. Our findings demonstrate for the first time that the attraction effect modulates subjective valuation even in the absence of choice. The findings also challenge the prospect of using neuroscientific methods to measure utility in a context-free manner and have important implications for theories of reinforcement learning and delay discounting. Many theories of value-based decision making assume that people first assess the attractiveness of each option independently of each other and then pick the option with the highest subjective value. The attraction effect, however, shows that adding a new option to a choice set can change the relative value of the existing options, which is a violation of the independence principle. Using an intertemporal choice framework, we tested whether such violations also occur when the brain encodes the difference between expected and received rewards (i.e., the reward prediction error). Our results suggest that neither intertemporal choice nor valuation without choice adhere to the independence principle. Copyright © 2017 the authors 0270-6474/17/370371-12$15.00/0.

Money earlier or later? Simple heuristics explain intertemporal choices better than delay discounting does.

PubMed

Ericson, Keith M Marzilli; White, John Myles; Laibson, David; Cohen, Jonathan D

2015-06-01

Heuristic models have been proposed for many domains involving choice. We conducted an out-of-sample, cross-validated comparison of heuristic models of intertemporal choice (which can account for many of the known intertemporal choice anomalies) and discounting models. Heuristic models outperformed traditional utility-discounting models, including models of exponential and hyperbolic discounting. The best-performing models predicted choices by using a weighted average of absolute differences and relative percentage differences of the attributes of the goods in a choice set. We concluded that heuristic models explain time-money trade-off choices in experiments better than do utility-discounting models. © The Author(s) 2015.

Intertemporal consumption with directly measured welfare functions and subjective expectations

PubMed Central

Kapteyn, Arie; Kleinjans, Kristin J.; van Soest, Arthur

2010-01-01

Euler equation estimation of intertemporal consumption models requires many, often unverifiable assumptions. These include assumptions on expectations and preferences. We aim at reducing some of these requirements by using direct subjective information on respondents’ preferences and expectations. The results suggest that individually measured welfare functions and expectations have predictive power for the variation in consumption across households. Furthermore, estimates of the intertemporal elasticity of substitution based on the estimated welfare functions are plausible and of a similar order of magnitude as other estimates found in the literature. The model favored by the data only requires cross-section data for estimation. PMID:20442798

How decisions emerge: action dynamics in intertemporal decision making.

PubMed

Dshemuchadse, Maja; Scherbaum, Stefan; Goschke, Thomas

2013-02-01

In intertemporal decision making, individuals prefer smaller rewards delivered sooner over larger rewards delivered later, often to an extent that seems irrational from an economical perspective. This behavior has been attributed to a lack of self-control and reflection, the nonlinearity of human time perception, and several other sources. Although an increasing number of models propose different mathematical descriptions of temporal discounting, the dynamics of the decision process behind temporal discounting are much less clear. In this study, we obtained further insights into the mechanisms of intertemporal decisions by observing choice action dynamics via a novel combination of continuously recorded mouse movements and a multiple regression approach. Participants had to choose between two hypothetical options (sooner/smaller vs. later/larger) by moving the mouse cursor from the bottom of the screen either to the top left or to the top right. We observed less direct mouse movements when participants chose later/larger rewards, indicating that participants had to overcome the attraction of the sooner/smaller reward first. Additionally, our results suggest that framing time information differently changes the weighting of value. We conclude that using a continuous process-oriented approach could further advance the understanding of intertemporal choice beyond the identification of the best fitted mathematical description of the discounting function by uncovering the way intertemporal decisions are performed. 2013 APA, all rights reserved

How Decisions Emerge: Action Dynamics in Intertemporal Decision Making

ERIC Educational Resources Information Center

Dshemuchadse, Maja; Scherbaum, Stefan; Goschke, Thomas

2013-01-01

In intertemporal decision making, individuals prefer smaller rewards delivered sooner over larger rewards delivered later, often to an extent that seems irrational from an economical perspective. This behavior has been attributed to a lack of self-control and reflection, the nonlinearity of human time perception, and several other sources.…

Endowment Spending Rates, Intergenerational Equity and the Sources of Capital Gains

ERIC Educational Resources Information Center

Woglom, Geoffrey

2003-01-01

This paper analyzes how James Tobin's widely cited concept of "intergenerational equity" for university endowments relates to the economic concepts of intertemporal substitutability and risk aversion. I show that Tobin's concept of intergenerational equity is a very special case of intertemporal substitutability; a special case that implies very…

Relatively high motivation for context-evoked reward produces the magnitude effect in rats.

PubMed

Yuki, Shoko; Okanoya, Kazuo

2014-09-01

Using a concurrent-chain schedule, we demonstrated the effect of absolute reinforcement (i.e., the magnitude effect) on choice behavior in rats. In general, animals' simultaneous choices conform to a relative reinforcement ratio between alternatives. However, studies in pigeons and rats have found that on a concurrent-chain schedule, the overall reinforcement ratio, or absolute amount, also influences choice. The effect of reinforcement amount has also been studied in inter-temporal choice situations, and this effect has been referred to as the magnitude effect. The magnitude effect has been observed in humans under various conditions, but little research has assessed it in animals (e.g., pigeons and rats). The present study confirmed the effect of reinforcement amount in rats during simultaneous and inter-temporal choice situations. We used a concurrent-chain procedure to examine the cause of the magnitude effect during inter-temporal choice. Our results suggest that rats can use differences in reinforcement amount as a contextual cue during choice, and the direction of the magnitude effect in rats might be similar to humans when using the present procedure. Furthermore, our results indicate that the magnitude effect was caused by the initial-link effect when the reinforcement amount was relatively small, while a loss aversion tendency was observed when the reinforcement amount changed within a session. The emergence of the initial-link effect and loss aversion suggests that rats make choices through cognitive processes predicted by prospect theory. Copyright © 2014 Elsevier B.V. All rights reserved.

Poverty and Economic Decision-Making: Evidence from Changes in Financial Resources at Payday

PubMed Central

Carvalho, Leandro S.; Meier, Stephan; Wang, Stephanie W.

2016-01-01

We study the effect of financial resources on decision-making. Low-income U.S. households are randomly assigned to receive an online survey before or after payday. The survey collects measures of cognitive function and administers risk and intertemporal choice tasks. The study design generates variation in cash, checking and savings balances, and expenditures. Before-payday participants behave as if they are more present-biased when making intertemporal choices about monetary rewards but not when making intertemporal choices about non-monetary real-effort tasks. Nor do we find before-after differences in risk-taking, the quality of decision-making, the performance in cognitive function tasks, or in heuristic judgments. PMID:28003681

The Causes of and Gains from Intertemporal Trade

ERIC Educational Resources Information Center

Craighead, William D.; Miller, Norman C.

2010-01-01

The authors show how the causes of and the gains from current account imbalances can be integrated into undergraduate economics courses using the same pedagogical tools that are used to explain comparative advantage and the gains from trade. A nonzero current account provides a mechanism for intertemporal trade, and a country has a comparative…

Time and Outcome Framing in Intertemporal Tradeoffs

ERIC Educational Resources Information Center

Scholten, Marc; Read, Daniel

2013-01-01

A robust anomaly in intertemporal choice is the delay-speedup asymmetry: Receipts are discounted more, and payments are discounted less, when delayed than when expedited over the same interval. We developed 2 versions of the tradeoff model (Scholten & Read, 2010) to address such situations, in which an outcome is expected at a given time but…

The Intertemporal Stability of Teacher Effect Estimates. Working Paper 2008-22

ERIC Educational Resources Information Center

McCaffrey, Daniel F.; Sass, Tim R.; Lockwood, J.R.

2008-01-01

Recently, a number of school districts have begun using measures of teachers' contributions to student test scores or teacher "value added" to determine salaries and other monetary rewards. In this paper we investigate the precision of value-added measures by analyzing their inter-temporal stability. We find that these measures of…

Building a Bridge into the Future: Dynamic Connectionist Modeling as an Integrative Tool for Research on Intertemporal Choice

PubMed Central

Scherbaum, Stefan; Dshemuchadse, Maja; Goschke, Thomas

2012-01-01

Temporal discounting denotes the fact that individuals prefer smaller rewards delivered sooner over larger rewards delivered later, often to a higher extent than suggested by normative economical theories. In this article, we identify three lines of research studying this phenomenon which aim (i) to describe temporal discounting mathematically, (ii) to explain observed choice behavior psychologically, and (iii) to predict the influence of specific factors on intertemporal decisions. We then opt for an approach integrating postulated mechanisms and empirical findings from these three lines of research. Our approach focuses on the dynamical properties of decision processes and is based on computational modeling. We present a dynamic connectionist model of intertemporal choice focusing on the role of self-control and time framing as two central factors determining choice behavior. Results of our simulations indicate that the two influences interact with each other, and we present experimental data supporting this prediction. We conclude that computational modeling of the decision process dynamics can advance the integration of different strands of research in intertemporal choice. PMID:23181048

Preliminary evidence of altered neural response during intertemporal choice of losses in adult attention-deficit hyperactivity disorder.

PubMed

Tanaka, Saori C; Yahata, Noriaki; Todokoro, Ayako; Kawakubo, Yuki; Kano, Yukiko; Nishimura, Yukika; Ishii-Takahashi, Ayaka; Ohtake, Fumio; Kasai, Kiyoto

2018-04-30

Impulsive behaviours are common symptoms of attention-deficit hyperactivity disorder (ADHD). Although previous studies have suggested functional models of impulsive behaviour, a full explanation of impulsivity in ADHD remains elusive. To investigate the detailed mechanisms behind impulsive behaviour in ADHD, we applied an economic intertemporal choice task involving gains and losses to adults with ADHD and healthy controls and measured brain activity by functional magnetic resonance imaging. In the intertemporal choice of future gains, we observed no behavioural or neural difference between the two groups. In the intertemporal choice of future losses, adults with ADHD exhibited higher discount rates than the control participants. Furthermore, a comparison of brain activity representing the sensitivity of future loss in the two groups revealed significantly lower activity in the striatum and higher activity in the amygdala in adults with ADHD than in controls. Our preliminary findings suggest that an altered size sensitivity to future loss is involved in apparent impulsive choice behaviour in adults with ADHD and shed light on the multifaceted impulsivity underlying ADHD.

Building a bridge into the future: dynamic connectionist modeling as an integrative tool for research on intertemporal choice.

PubMed

Scherbaum, Stefan; Dshemuchadse, Maja; Goschke, Thomas

2012-01-01

Temporal discounting denotes the fact that individuals prefer smaller rewards delivered sooner over larger rewards delivered later, often to a higher extent than suggested by normative economical theories. In this article, we identify three lines of research studying this phenomenon which aim (i) to describe temporal discounting mathematically, (ii) to explain observed choice behavior psychologically, and (iii) to predict the influence of specific factors on intertemporal decisions. We then opt for an approach integrating postulated mechanisms and empirical findings from these three lines of research. Our approach focuses on the dynamical properties of decision processes and is based on computational modeling. We present a dynamic connectionist model of intertemporal choice focusing on the role of self-control and time framing as two central factors determining choice behavior. Results of our simulations indicate that the two influences interact with each other, and we present experimental data supporting this prediction. We conclude that computational modeling of the decision process dynamics can advance the integration of different strands of research in intertemporal choice.

Decision making generalized by a cumulative probability weighting function

NASA Astrophysics Data System (ADS)

dos Santos, Lindomar Soares; Destefano, Natália; Martinez, Alexandre Souto

2018-01-01

Typical examples of intertemporal decision making involve situations in which individuals must choose between a smaller reward, but more immediate, and a larger one, delivered later. Analogously, probabilistic decision making involves choices between options whose consequences differ in relation to their probability of receiving. In Economics, the expected utility theory (EUT) and the discounted utility theory (DUT) are traditionally accepted normative models for describing, respectively, probabilistic and intertemporal decision making. A large number of experiments confirmed that the linearity assumed by the EUT does not explain some observed behaviors, as nonlinear preference, risk-seeking and loss aversion. That observation led to the development of new theoretical models, called non-expected utility theories (NEUT), which include a nonlinear transformation of the probability scale. An essential feature of the so-called preference function of these theories is that the probabilities are transformed by decision weights by means of a (cumulative) probability weighting function, w(p) . We obtain in this article a generalized function for the probabilistic discount process. This function has as particular cases mathematical forms already consecrated in the literature, including discount models that consider effects of psychophysical perception. We also propose a new generalized function for the functional form of w. The limiting cases of this function encompass some parametric forms already proposed in the literature. Far beyond a mere generalization, our function allows the interpretation of probabilistic decision making theories based on the assumption that individuals behave similarly in the face of probabilities and delays and is supported by phenomenological models.

Student Effort in Preparing for Exams: Intertemporal Preferences and Loss Aversion

ERIC Educational Resources Information Center

Wüst, Kirsten; Beck, Hanno

2012-01-01

In the last two decades, much empirical research has been done in the field of behavioral economics to explain the psychological foundations for economic decisions. In particular, it has been shown that people exhibit time-inconsistent behavior when making intertemporal decisions, i.e., they demand higher interest rates for a delay of their…

Drift: An Analysis of Outcome Framing in Intertemporal Choice

ERIC Educational Resources Information Center

Read, Daniel; Frederick, Shane; Scholten, Marc

2013-01-01

People prefer to receive good outcomes immediately rather than wait, and they must be compensated for waiting. But what influences their decision about how much compensation is required for a given wait? To give a partial answer to this question, we develop the DRIFT model, a heuristic description of how framing influences intertemporal choice. We…

Future Time Perspective Impacts Gain-Related but Not Loss-Related Intertemporal Choice.

PubMed

Li, Tian; Tan, Yuxin; Gong, Xianmin; Yin, Shufei; Qiu, Fangshu; Hu, Xue

2018-01-01

Future time perspective (FTP) modulates individuals' temporal orientation in selecting their motivations and goals, which widely influences their cognitions and behaviors. However, it remains unclear how FTP exactly affects intertemporal choice. To clarify the effect of FTP on intertemporal choice, 90 college students ( M age = 21.70, SD = 1.23) were randomly assigned to the limited FTP condition (16 males, 29 females) and the open-ended FTP condition (17 males, 28 females). In the limited FTP condition, participants were instructed to imagine their states of being 70 years old, whereas in the open-ended FTP condition, they were instructed to describe their current states. All participants then completed a series of intertemporal choice tasks, in which they chose from gain- and loss-related choices occurring at various time points. Results showed that the participants who received the future-imagining manipulation had more limited FTP compared with those who did not receive the manipulation, which confirmed the validity of the FTP manipulation. A 2 (FTP: limited vs. open-ended) × 2 (type of choice: gain vs. loss) repeated measures ANOVA on discount rate revealed a significant interaction between these two factors. The participants in the limited FTP condition had higher discount rates on gain-related choices but showed no difference on loss-related choices compared with the participants under the open-ended FTP condition. The results suggest that limited FTP could lower individuals' future orientation (i.e., willingness to delay an outcome) on gain-related, but not on loss-related, intertemporal decision-making.

Future Time Perspective Impacts Gain-Related but Not Loss-Related Intertemporal Choice

PubMed Central

Li, Tian; Tan, Yuxin; Gong, Xianmin; Yin, Shufei; Qiu, Fangshu; Hu, Xue

2018-01-01

Future time perspective (FTP) modulates individuals’ temporal orientation in selecting their motivations and goals, which widely influences their cognitions and behaviors. However, it remains unclear how FTP exactly affects intertemporal choice. To clarify the effect of FTP on intertemporal choice, 90 college students (Mage = 21.70, SD = 1.23) were randomly assigned to the limited FTP condition (16 males, 29 females) and the open-ended FTP condition (17 males, 28 females). In the limited FTP condition, participants were instructed to imagine their states of being 70 years old, whereas in the open-ended FTP condition, they were instructed to describe their current states. All participants then completed a series of intertemporal choice tasks, in which they chose from gain- and loss-related choices occurring at various time points. Results showed that the participants who received the future-imagining manipulation had more limited FTP compared with those who did not receive the manipulation, which confirmed the validity of the FTP manipulation. A 2 (FTP: limited vs. open-ended) × 2 (type of choice: gain vs. loss) repeated measures ANOVA on discount rate revealed a significant interaction between these two factors. The participants in the limited FTP condition had higher discount rates on gain-related choices but showed no difference on loss-related choices compared with the participants under the open-ended FTP condition. The results suggest that limited FTP could lower individuals’ future orientation (i.e., willingness to delay an outcome) on gain-related, but not on loss-related, intertemporal decision-making. PMID:29695989

Intertemporal Consistency of Predictors of Student Performance: Evidence from a Business Administration Program

ERIC Educational Resources Information Center

Richter, Ansgar

2006-01-01

In this article, the author analyzes the intertemporal consistency of high school grades as predictors of the academic performance of business administration students over a 2-year period by using data from a university in Germany. This study shows how students' average high school grades and a range of other factors are regressed on the students'…

Does fertility status influence impulsivity and risk taking in human females? Adaptive influences on intertemporal choice and risky decision making.

PubMed

Kaighobadi, Farnaz; Stevens, Jeffrey R

2013-07-18

Informed by the research on adaptive decision making in other animal species, this study investigated human females' intertemporal and risky choices across the ovulatory cycle. We tested the hypothesis that at peak fertility, women who are exposed to environments that signal availability of higher quality mates (by viewing images of attractive males), become more impulsive and risk-seeking in economic decision tasks. To test this, we collected intertemporal and risky choice measures before and after exposure to images of either attractive males or neutral landscapes both at peak and low fertility conditions. The results showed an interaction between women's fertility status and image type, such that women at peak fertility viewing images of attractive men chose the smaller, sooner monetary reward option less than women at peak fertility viewing neutral images. Neither fertility status nor image type influenced risky choice. Thus, though exposure to images of men altered intertemporal choices at peak fertility, this occurred in the opposite direction than predicted--i.e., women at peak fertility became less impulsive. Nevertheless, the results of the current study provide evidence for shifts in preferences over the ovulatory cycle and opens future research on economic decision making.

Do You Look to the Future or Focus on Today? The Impact of Life Experience on Intertemporal Decisions

ERIC Educational Resources Information Center

Liu, Wendy; Aaker, Jennifer

2007-01-01

In this research, we investigate the impact of significant life experiences on intertemporal decisions among young adults. A series of experiments focus specifically on the impact of experiencing the death of a close other by cancer. We show that such an experience, which bears information about time, is associated with making decisions that favor…

Incidental rewarding cues influence economic decisions in people with obesity.

PubMed

Simmank, Jakob; Murawski, Carsten; Bode, Stefan; Horstmann, Annette

2015-01-01

Recent research suggests that obesity is linked to prominent alterations in learning and decision-making. This general difference may also underlie the preference for immediately consumable, highly palatable but unhealthy and high-calorie foods. Such poor food-related inter-temporal decision-making can explain weight gain; however, it is not yet clear whether this deficit can be generalized to other domains of inter-temporal decision-making, for example financial decisions. Further, little is known about the stability of decision-making behavior in obesity, especially in the presence of rewarding cues. To answer these questions, obese and lean participants (n = 52) completed two sessions of a novel priming paradigm including a computerized monetary delay discounting task. In the first session, general differences between groups in financial delay discounting were measured. In the second session, we tested the general stability of discount rates. Additionally, participants were primed by affective visual cues of different contextual categories before making financial decisions. We found that the obese group showed stronger discounting of future monetary rewards than the lean group, but groups did not differ in their general stability between sessions nor in their sensitivity toward changes in reward magnitude. In the obese group, a fast decrease of subjective value over time was directly related to a higher tendency for opportunistic eating. Obese in contrast to lean people were primed by the affective cues, showing a sex-specific pattern of priming direction. Our findings demonstrate that environments rich of cues, aiming at inducing unhealthy consumer decisions, can be highly detrimental for obese people. It also underscores that obesity is not merely a medical condition but has a strong cognitive component, meaning that current dietary and medical treatment strategies may fall too short.

Incidental rewarding cues influence economic decisions in people with obesity

PubMed Central

Simmank, Jakob; Murawski, Carsten; Bode, Stefan; Horstmann, Annette

2015-01-01

Recent research suggests that obesity is linked to prominent alterations in learning and decision-making. This general difference may also underlie the preference for immediately consumable, highly palatable but unhealthy and high-calorie foods. Such poor food-related inter-temporal decision-making can explain weight gain; however, it is not yet clear whether this deficit can be generalized to other domains of inter-temporal decision-making, for example financial decisions. Further, little is known about the stability of decision-making behavior in obesity, especially in the presence of rewarding cues. To answer these questions, obese and lean participants (n = 52) completed two sessions of a novel priming paradigm including a computerized monetary delay discounting task. In the first session, general differences between groups in financial delay discounting were measured. In the second session, we tested the general stability of discount rates. Additionally, participants were primed by affective visual cues of different contextual categories before making financial decisions. We found that the obese group showed stronger discounting of future monetary rewards than the lean group, but groups did not differ in their general stability between sessions nor in their sensitivity toward changes in reward magnitude. In the obese group, a fast decrease of subjective value over time was directly related to a higher tendency for opportunistic eating. Obese in contrast to lean people were primed by the affective cues, showing a sex-specific pattern of priming direction. Our findings demonstrate that environments rich of cues, aiming at inducing unhealthy consumer decisions, can be highly detrimental for obese people. It also underscores that obesity is not merely a medical condition but has a strong cognitive component, meaning that current dietary and medical treatment strategies may fall too short. PMID:26528158

Dissociations between interval timing and intertemporal choice following administration of fluoxetine, cocaine, or methamphetamine

PubMed Central

Heilbronner, Sarah R.; Meck, Warren. H.

2014-01-01

The goal of our study was to characterize the relationship between intertemporal choice and interval timing, including determining how drugs that modulate brain serotonin and dopamine levels influence these two processes. In Experiment 1, rats were tested on a standard 40-s peak-interval procedure following administration of fluoxetine (3, 5, or 8 mg/kg) or vehicle to assess basic effects on interval timing. In Experiment 2, rats were tested in a novel behavioral paradigm intended to simultaneously examine interval timing and impulsivity. Rats performed a variant of the bi-peak procedure using 10-s and 40-s target durations with an additional “defection” lever that provided the possibility of a small, immediate reward. Timing functions remained relatively intact, and ‘patience’ across subjects correlated with peak times, indicating a negative relationship between ‘patience’ and clock speed. We next examined the effects of fluoxetine (5 mg/kg), cocaine (15 mg/kg), or methamphetamine (1 mg/kg) on task performance. Fluoxetine reduced impulsivity as measured by defection time without corresponding changes in clock speed. In contrast, cocaine and methamphetamine both increased impulsivity and clock speed. Thus, variations in timing may mediate intertemporal choice via dopaminergic inputs. However, a separate, serotonergic system can affect intertemporal choice without affecting interval timing directly. PMID:24135569

Intertemporal bargaining predicts moral behavior, even in anonymous, one-shot economic games.

PubMed

Ainslie, George

2013-02-01

To the extent that acting fairly is in an individual’s long-term interest, short-term impulses to cheat present a self-control problem. The only effective solution is to interpret the problem as a variant of repeated prisoner’s dilemma, with each choice as a test case predicting future choices. Moral choice appears to be the product of a contract because it comes from self-enforcing intertemporal cooperation.

The economics of subnational carbon policy interactions and integration

NASA Astrophysics Data System (ADS)

Rahman, Fadli

An integrated, nationwide carbon policy is essential to achieve US environmental targets relating to carbon emissions. The carbon policy literature is loaded with qualitative analysis of the implications or mechanisms of an integrated emissions market across the US, but current quantitative studies do not offer solutions regarding the interactions of coexisting US regional emission markets and other policy instruments. Therefore, this dissertation attempts to answer three fundamental concerns about US carbon policy. The second chapter analyzes the welfare implications of different relative stringencies of cap-setting under a proposed integration of two emissions markets, considering the attributes relevant to each market. The third chapter extends this market integration analysis by adding an intertemporal feature to analyze the consequences of integrating existing emission markets in the US (i.e., California and RGGI). The fourth chapter examines the adverse economic implications of adopting several overlapping carbon policy instruments to regulate carbon emissions in a region. The second and third chapters employ a simple structural model with a stochastic variable to account for uncertainties in emissions. The fourth chapter utilizes a static general equilibrium framework based on IMPLAN data for California to comprehensively evaluate the reactions of the state-wide economy to various carbon policy settings. In general, the results show that integrating existing emissions markets could generate both positive and negative effects on economic welfare. The positive effects result from gains from trading permits, while negative results come from perverse second-best interactions. Policymakers are expected to carefully consider the factors and attributes of all regions prior to setting their policy targets and designing an integrated system of carbon reduction.

Gender-Specific Differences in the Relationship between Autobiographical Memory and Intertemporal Choice in Older Adults

PubMed Central

Seinstra, Maayke; Grzymek, Katharina; Kalenscher, Tobias

2015-01-01

As the population of older adults grows, their economic choices will have increasing impact on society. Research on the effects of aging on intertemporal decisions shows inconsistent, often opposing results, indicating that yet unexplored factors might play an essential role in guiding one's choices. Recent studies suggest that episodic future thinking, which is based on the same neural network involved in episodic memory functions, leads to reductions in discounting of future rewards. As episodic memory functioning declines with normal aging, but to greatly variable degrees, individual differences in delay discounting might be due to individual differences in the vitality of this memory system in older adults. We investigated this hypothesis, using a sample of healthy older adults who completed an intertemporal choice task as well as two episodic memory tasks. We found no clear evidence for a relationship between episodic memory performance and delay discounting in older adults. However, when additionally considering gender differences, we found an interaction effect of gender and autobiographical memory on delay discounting: while men with higher memory scores showed less delay discounting, women with higher memory scores tended to discount the future more. We speculate that this gender effect might stem from the gender-specific use of different modal representation formats (i.e. temporal or visual) during assessment of intertemporal choice options. PMID:26335426

Time and outcome framing in intertemporal tradeoffs.

PubMed

Scholten, Marc; Read, Daniel

2013-07-01

A robust anomaly in intertemporal choice is the delay-speedup asymmetry: Receipts are discounted more, and payments are discounted less, when delayed than when expedited over the same interval. We developed 2 versions of the tradeoff model (Scholten & Read, 2010) to address such situations, in which an outcome is expected at a given time but then its timing is changed. The outcome framing model generalizes the approach taken by the hyperbolic discounting model (Loewenstein & Prelec, 1992): Not obtaining a positive outcome when expected is a worse than expected state, to which people are over-responsive, or hypersensitive, and not incurring a negative outcome when expected is a better than expected state, to which people are under-responsive, or hyposensitive. The time framing model takes a new approach: Delaying a positive outcome or speeding up a negative one involves a loss of time to which people are hypersensitive, and speeding up a positive outcome or delaying a negative one involves a gain of time to which people are hyposensitive. We compare the models on their quantitative predictions of indifference data from matching and preference data from choice. The time framing model systematically outperforms the outcome framing model. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Propranolol reduces reference-dependence in intertemporal choice

PubMed Central

Lempert, Karolina M.; Lackovic, Sandra F.; Tobe, Russell H.; Glimcher, Paul W.

2017-01-01

Abstract In intertemporal choices between immediate and delayed rewards, people tend to prefer immediate rewards, often even when the delayed reward is larger. This is known as temporal discounting. It has been proposed that this tendency emerges because immediate rewards are more emotionally arousing than delayed rewards. However, in our previous research, we found no evidence for this but instead found that arousal responses (indexed with pupil dilation) in intertemporal choice are context-dependent. Specifically, arousal tracks the subjective value of the more variable reward option in the paradigm, whether it is immediate or delayed. Nevertheless, people tend to choose the less variable option in the choice task. In other words, their choices are reference-dependent and depend on variance in their recent history of offers. This suggests that there may be a causal relationship between reference-dependent choice and arousal, which we investigate here by reducing arousal pharmacologically using propranolol. Here, we show that propranolol reduces reference-dependence, leading to choices that are less influenced by recent history and more internally consistent. PMID:28992268

Temporal Discounting and Inter-Temporal Choice in Rhesus Monkeys

PubMed Central

Hwang, Jaewon; Kim, Soyoun; Lee, Daeyeol

2009-01-01

Humans and animals are more likely to take an action leading to an immediate reward than actions with delayed rewards of similar magnitudes. Although such devaluation of delayed rewards has been almost universally described by hyperbolic discount functions, the rate of this temporal discounting varies substantially among different animal species. This might be in part due to the differences in how the information about reward is presented to decision makers. In previous animal studies, reward delays or magnitudes were gradually adjusted across trials, so the animals learned the properties of future rewards from the rewards they waited for and consumed previously. In contrast, verbal cues have been used commonly in human studies. In the present study, rhesus monkeys were trained in a novel inter-temporal choice task in which the magnitude and delay of reward were indicated symbolically using visual cues and varied randomly across trials. We found that monkeys could extract the information about reward delays from visual symbols regardless of the number of symbols used to indicate the delay. The rate of temporal discounting observed in the present study was comparable to the previous estimates in other mammals, and the animal's choice behavior was largely consistent with hyperbolic discounting. Our results also suggest that the rate of temporal discounting might be influenced by contextual factors, such as the novelty of the task. The flexibility furnished by this new inter-temporal choice task might be useful for future neurobiological investigations on inter-temporal choice in non-human primates. PMID:19562091

Search predicts and changes patience in intertemporal choice

PubMed Central

Johnson, Eric J.

2017-01-01

Intertemporal choice impacts many important outcomes, such as decisions about health, education, wealth, and the environment. However, the psychological processes underlying decisions involving outcomes at different points in time remain unclear, limiting opportunities to intervene and improve people’s patience. This research examines information-search strategies used during intertemporal choice and their impact on decisions. In experiment 1, we demonstrate that search strategies vary substantially across individuals. We subsequently identify two distinct search strategies across individuals. Comparative searchers, who compare features across options, discount future options less and are more susceptible to acceleration versus delay framing than integrative searchers, who integrate the features of an option. Experiment 2 manipulates search using an unobtrusive method to establish a causal relationship between strategy and choice, randomly assigning participants to conditions promoting either comparative or integrative search. Again, comparative search promotes greater patience than integrative search. Additionally, when participants adopt a comparative search strategy, they also exhibit greater effects of acceleration versus delay framing. Although most participants reported that the manipulation did not change their behavior, promoting comparative search decreased discounting of future rewards substantially and speeded patient choices. These findings highlight the central role that heterogeneity in psychological processes plays in shaping intertemporal choice. Importantly, these results indicate that theories that ignore variability in search strategies may be inadvertently aggregating over different subpopulations that use very different processes. The findings also inform interventions in choice architecture to increase patience and improve consumer welfare. PMID:29078303

Time Is Money: The Decision Making of Smartphone High Users in Gain and Loss Intertemporal Choice.

PubMed

Tang, Zixuan; Zhang, Huijun; Yan, An; Qu, Chen

2017-01-01

Nowadays the smartphone plays an important role in our lives. While it brings us convenience and efficiency, its overuse can cause problems. Although a great number of studies have demonstrated that people affected by substance abuse, pathological gambling, and internet addiction disorder have lower self-control than average, scarcely any study has investigated the decision making of smartphone high users by using a behavioral paradigm. The present study employed an intertemporal task, the Smartphone Addiction Inventory (SPAI) and the Barratt Impulsiveness Scale 11th version (BIS-11) to explore the decision control of smartphone high users in a sample of 125 college students. Participants were divided into three groups according to their SPAI scores. The upper third (69 or higher), middle third (from 61 to 68) and lower third (60 or lower) of scores were defined as high smartphone users, medium users and low users, respectively. We compared the percentage of small immediate reward/penalty choices in different conditions between the three groups. Relative to the low users group, high users and medium users were more inclined to request an immediate monetary reward. Moreover, for the two dimensions of time and money in intertemporal choice, high users and medium users showed a bias in intertemporal choice task among most of the time points and value magnitude compared to low users. These findings demonstrated that smartphone overuse was associated with problematic decision-making, a pattern similar to that seen in persons affected by a variety of addictions.

Search predicts and changes patience in intertemporal choice.

PubMed

Reeck, Crystal; Wall, Daniel; Johnson, Eric J

2017-11-07

Intertemporal choice impacts many important outcomes, such as decisions about health, education, wealth, and the environment. However, the psychological processes underlying decisions involving outcomes at different points in time remain unclear, limiting opportunities to intervene and improve people's patience. This research examines information-search strategies used during intertemporal choice and their impact on decisions. In experiment 1, we demonstrate that search strategies vary substantially across individuals. We subsequently identify two distinct search strategies across individuals. Comparative searchers, who compare features across options, discount future options less and are more susceptible to acceleration versus delay framing than integrative searchers, who integrate the features of an option. Experiment 2 manipulates search using an unobtrusive method to establish a causal relationship between strategy and choice, randomly assigning participants to conditions promoting either comparative or integrative search. Again, comparative search promotes greater patience than integrative search. Additionally, when participants adopt a comparative search strategy, they also exhibit greater effects of acceleration versus delay framing. Although most participants reported that the manipulation did not change their behavior, promoting comparative search decreased discounting of future rewards substantially and speeded patient choices. These findings highlight the central role that heterogeneity in psychological processes plays in shaping intertemporal choice. Importantly, these results indicate that theories that ignore variability in search strategies may be inadvertently aggregating over different subpopulations that use very different processes. The findings also inform interventions in choice architecture to increase patience and improve consumer welfare. Copyright © 2017 the Author(s). Published by PNAS.

Time Is Money: The Decision Making of Smartphone High Users in Gain and Loss Intertemporal Choice

PubMed Central

Tang, Zixuan; Zhang, Huijun; Yan, An; Qu, Chen

2017-01-01

Nowadays the smartphone plays an important role in our lives. While it brings us convenience and efficiency, its overuse can cause problems. Although a great number of studies have demonstrated that people affected by substance abuse, pathological gambling, and internet addiction disorder have lower self-control than average, scarcely any study has investigated the decision making of smartphone high users by using a behavioral paradigm. The present study employed an intertemporal task, the Smartphone Addiction Inventory (SPAI) and the Barratt Impulsiveness Scale 11th version (BIS-11) to explore the decision control of smartphone high users in a sample of 125 college students. Participants were divided into three groups according to their SPAI scores. The upper third (69 or higher), middle third (from 61 to 68) and lower third (60 or lower) of scores were defined as high smartphone users, medium users and low users, respectively. We compared the percentage of small immediate reward/penalty choices in different conditions between the three groups. Relative to the low users group, high users and medium users were more inclined to request an immediate monetary reward. Moreover, for the two dimensions of time and money in intertemporal choice, high users and medium users showed a bias in intertemporal choice task among most of the time points and value magnitude compared to low users. These findings demonstrated that smartphone overuse was associated with problematic decision-making, a pattern similar to that seen in persons affected by a variety of addictions. PMID:28344568

Adapting to the destitute situations: poverty cues lead to short-term choice.

PubMed

Liu, Lei; Feng, Tingyong; Suo, Tao; Lee, Kang; Li, Hong

2012-01-01

Why do some people live for the present, whereas others save for the future? The evolutionary framework of life history theory predicts that preference for delay of gratification should be influenced by social economic status (SES). However, here we propose that the decision to choose alternatives in immediate and delayed gratification in poverty environments may have a psychological dimension. Specifically, the perception of environmental poverty cues may induce people alike to favor choices with short-term, likely smaller benefit than choices with long-term, greater benefit. The present study was conducted to explore how poverty and affluence cues affected individuals' intertemporal choices. In our first two experiments, individuals exposed explicitly (Experiment 1) and implicitly (Experiment 2) to poverty pictures (the poverty cue) were induced to prefer immediate gratification compared with those exposed to affluence pictures (the affluence cue). Furthermore, by the manipulation of temporary perceptions of poverty and affluence status using a lucky draw game; individuals in the poverty state were more impulsive in a manner, which made them pursue immediate gratification in intertemporal choices (Experiment 3). Thus, poverty cues can lead to short-term choices. Decision makers chose more frequently the sooner-smaller reward over the later-larger reward as they were exposed to the poverty cue. This indicates that it is that just the feeling of poverty influences intertemporal choice - the actual reality of poverty (restricted resources, etc.) is not necessary to get the effect. Furthermore, our findings emphasize that it is a change of the poverty-affluence status, not a trait change, can influence individual preference in intertemporal choice.

Sample selection and spatial models of housing price indexes, and, A disequilibrium analysis of the U.S. gasoline market using panel data

NASA Astrophysics Data System (ADS)

Hu, Haixin

This dissertation consists of two parts. The first part studies the sample selection and spatial models of housing price index using transaction data on detached single-family houses of two California metropolitan areas from 1990 through 2008. House prices are often spatially correlated due to shared amenities, or when the properties are viewed as close substitutes in a housing submarket. There have been many studies that address spatial correlation in the context of housing markets. However, none has used spatial models to construct housing price indexes at zip code level for the entire time period analyzed in this dissertation to the best of my knowledge. In this paper, I study a first-order autoregressive spatial model with four different weighing matrix schemes. Four sets of housing price indexes are constructed accordingly. Gatzlaff and Haurin (1997, 1998) study the sample selection problem in housing index by using Heckman's two-step method. This method, however, is generally inefficient and can cause multicollinearity problem. Also, it requires data on unsold houses in order to carry out the first-step probit regression. Maximum likelihood (ML) method can be used to estimate a truncated incidental model which allows one to correct for sample selection based on transaction data only. However, convergence problem is very prevalent in practice. In this paper I adopt Lewbel's (2007) sample selection correction method which does not require one to model or estimate the selection model, except for some very general assumptions. I then extend this method to correct for spatial correlation. In the second part, I analyze the U.S. gasoline market with a disequilibrium model that allows lagged-latent variables, endogenous prices, and panel data with fixed effects. Most existing studies (see the survey of Espey, 1998, Energy Economics) of the gasoline market assume equilibrium. In practice, however, prices do not always adjust fast enough to clear the market. Equilibrium assumptions greatly simplify statistical inference, but are very restrictive and can produce conflicting estimates. For example, econometric models of markets that assume equilibrium often produce more elastic demand price elasticity than their disequilibrium counterparts (Holt and Johnson, 1989, Review of Economics and Statistics, Oczkowski, 1998, Economics Letters). The few studies that allow disequilibrium, however, have been limited to macroeconomic time-series data without lagged-latent variables. While time series data allows one to investigate national trends, it cannot be used to identify and analyze regional differences and the role of local markets. Exclusion of the lagged-latent variables is also undesirable because such variables capture adjustment costs and inter-temporal spillovers. Simulation methods offer tractable solutions to dynamic and panel data disequilibrium models (Lee, 1997, Journal of Econometrics), but assume normally distributed errors. This paper compares estimates of price/income elasticity and excess supply/demand across time periods, regions, and model specifications, using both equilibrium and disequilibrium methods. In the equilibrium model, I compare the within group estimator with Anderson and Hsiao's first-difference 2SLS estimator. In the disequilibrium model, I extend Amemiya's 2SLS by using Newey's efficient estimator with optimal instruments.

Impacts of religious semantic priming on an intertemporal discounting task: Response time effects and neural correlates.

PubMed

Morgan, Jonathan; Clark, Dustin; Tripodis, Yorghos; Halloran, Christopher S; Minsky, April; Wildman, Wesley J; Durso, Raymon; McNamara, Patrick

2016-08-01

The purpose of this study is to test the hypothesis that religious primes would influence intertemporal discounting behaviors in neurotypical older adults, but not in participants with Parkinson's disease (PD). Furthermore, we predicted that this priming effect would be related to functional connectivity within neural networks mediating religious cognition, decision-making, reward valuing, and prospection processes. Contrary to past research with young adults, we found a significant positive relationship between religiosity and discounting rates. Religious semantic primes did not reliably shift individual discounting rates. But religious controls did respond more quickly to intertemporal decisions under the religious priming condition than the neutral condition, compared to response time differences among the participants with PD. Differences in response time were significantly associated with functional connectivity between the nucleus accumbens and various regions, including the left anterior cingulate cortex and Brodmann areas 10 and 46 in the right dorsolateral prefrontal cortex. These results suggest that religious primes influence discounting behavior via dopaminergic meso-limbic and right dorsolateral prefrontal supporting cognitive valuation and prospection processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cultural neuroeconomics of intertemporal choice.

PubMed

Takahashi, Taiki; Hadzibeganovic, Tarik; Cannas, Sergio A; Makino, Takaki; Fukui, Hiroki; Kitayama, Shinobu

2009-01-01

According to theories of cultural neuroscience, Westerners and Easterners may have distinct styles of cognition (e.g., different allocation of attention). Previous research has shown that Westerners and Easterners tend to utilize analytical and holistic cognitive styles, respectively. On the other hand, little is known regarding the cultural differences in neuroeconomic behavior. For instance, economic decisions may be affected by cultural differences in neurocomputational processing underlying attention; however, this area of neuroeconomics has been largely understudied. In the present paper, we attempt to bridge this gap by considering the links between the theory of cultural neuroscience and neuroeconomic theory of the role of attention in intertemporal choice. We predict that (i) Westerners are more impulsive and inconsistent in intertemporal choice in comparison to Easterners, and (ii) Westerners more steeply discount delayed monetary losses than Easterners. We examine these predictions by utilizing a novel temporal discounting model based on Tsallis' statistics (i.e. a q-exponential model). Our preliminary analysis of temporal discounting of gains and losses by Americans and Japanese confirmed the predictions from the cultural neuroeconomic theory. Future study directions, employing computational modeling via neural networks, are outlined and discussed.

Reduced Sensitivity to Sooner Reward During Intertemporal Decision-Making Following Insula Damage in Humans

PubMed Central

Sellitto, Manuela; Ciaramelli, Elisa; Mattioli, Flavia; di Pellegrino, Giuseppe

2016-01-01

During intertemporal choice, humans tend to prefer small-sooner rewards over larger-delayed rewards, reflecting temporal discounting (TD) of delayed outcomes. Functional neuroimaging (fMRI) evidence has implicated the insular cortex in time-sensitive decisions, yet it is not clear whether activity in this brain region is crucial for, or merely associated with, TD behavior. Here, patients with damage to the insula (Insular patients), control patients with lesions outside the insula, and healthy individuals chose between smaller-sooner and larger-later monetary rewards. Insular patients were less sensitive to sooner rewards than were the control groups, exhibiting reduced TD. A Voxel-based Lesion-Symptom Mapping (VLSM) analysis confirmed a statistically significant association between insular damage and reduced TD. These results indicate that the insular cortex is crucial for intertemporal choice. We suggest that he insula may be necessary to anticipate the bodily/emotional effects of receiving rewards at different delays, influencing the computation of their incentive value. Devoid of such input, insular patients’ choices would be governed by a heuristic of quantity, allowing patients to wait for larger options. PMID:26793084

Adapting to the Destitute Situations: Poverty Cues Lead to Short-Term Choice

PubMed Central

Suo, Tao; Lee, Kang; Li, Hong

2012-01-01

Background Why do some people live for the present, whereas others save for the future? The evolutionary framework of life history theory predicts that preference for delay of gratification should be influenced by social economic status (SES). However, here we propose that the decision to choose alternatives in immediate and delayed gratification in poverty environments may have a psychological dimension. Specifically, the perception of environmental poverty cues may induce people alike to favor choices with short-term, likely smaller benefit than choices with long-term, greater benefit. Methodology/Principal Findings The present study was conducted to explore how poverty and affluence cues affected individuals' intertemporal choices. In our first two experiments, individuals exposed explicitly (Experiment 1) and implicitly (Experiment 2) to poverty pictures (the poverty cue) were induced to prefer immediate gratification compared with those exposed to affluence pictures (the affluence cue). Furthermore, by the manipulation of temporary perceptions of poverty and affluence status using a lucky draw game; individuals in the poverty state were more impulsive in a manner, which made them pursue immediate gratification in intertemporal choices (Experiment 3). Thus, poverty cues can lead to short-term choices. Conclusions/Significance Decision makers chose more frequently the sooner-smaller reward over the later-larger reward as they were exposed to the poverty cue. This indicates that it is that just the feeling of poverty influences intertemporal choice – the actual reality of poverty (restricted resources, etc.) is not necessary to get the effect. Furthermore, our findings emphasize that it is a change of the poverty-affluence status, not a trait change, can influence individual preference in intertemporal choice. PMID:22529902

Dual conception of risk in the Iowa Gambling Task: effects of sleep deprivation and test-retest gap.

PubMed

Singh, Varsha

2013-01-01

Risk in the Iowa Gambling Task (IGT) is often understood in terms of intertemporal choices, i.e., preference for immediate outcomes in favor of delayed outcomes is considered risky decision making. According to behavioral economics, healthy decision makers are expected to refrain from choosing the short-sighted immediate gain because, over time (10 trials of the IGT), the immediate gains result in a long term loss (net loss). Instead decision makers are expected to maximize their gains by choosing options that, over time (10 trials), result in delayed or long term gains (net gain). However, task choices are sometimes made on the basis of the frequency of reward and punishment such that frequent rewards/infrequent punishments are favored over infrequent rewards/frequent punishments. The presence of these two attributes (intertemporality and frequency of reward) in IGT decision making may correspond to the emotion-cognition dichotomy and reflect a dual conception of risk. Decision making on the basis of the two attributes was tested under two conditions: delay in retest and sleep deprivation. An interaction between sleep deprivation and time delay was expected to attenuate the difference between the two attributes. Participants were 40 male university students. Analysis of the effects of IGT attribute type (intertemporal vs. frequency of reinforcement), sleep deprivation (sleep deprivation vs. no sleep deprivation), and test-retest gap (short vs. long delay) showed a significant within-subjects effect of IGT attribute type thus confirming the difference between the two attributes. Sleep deprivation had no effect on the attributes, but test-retest gap and the three-way interaction between attribute type, test-retest gap, and sleep deprivation were significantly different. Post-hoc tests revealed that sleep deprivation and short test-retest gap attenuated the difference between the two attributes. Furthermore, the results showed an expected trend of increase in intertemporal decision making at retest suggesting that intertemporal decision making benefited from repeated task exposure. The present findings add to understanding of the emotion-cognition dichotomy. Further, they show an important time-dependent effect of a universally experienced constraint (sleep deprivation) on decision making. It is concluded that risky decision making in the IGT is contingent on the attribute under consideration and is affected by factors such as time elapsed and constraint experienced before the retest.

Abstract generalized vector quasi-equilibrium problems in noncompact Hadamard manifolds.

PubMed

Lu, Haishu; Wang, Zhihua

2017-01-01

This paper deals with the abstract generalized vector quasi-equilibrium problem in noncompact Hadamard manifolds. We prove the existence of solutions to the abstract generalized vector quasi-equilibrium problem under suitable conditions and provide applications to an abstract vector quasi-equilibrium problem, a generalized scalar equilibrium problem, a scalar equilibrium problem, and a perturbed saddle point problem. Finally, as an application of the existence of solutions to the generalized scalar equilibrium problem, we obtain a weakly mixed variational inequality and two mixed variational inequalities. The results presented in this paper unify and generalize many known results in the literature.

Pramipexole-induced disruption of behavioral processes fundamental to intertemporal choice.

PubMed

Johnson, Patrick S; Stein, Jeffrey S; Smits, Rochelle R; Madden, Gregory J

2013-05-01

Evaluating the effects of presession drug administration on intertemporal choice in nonhumans is a useful approach for identifying compounds that promote impulsive behavior in clinical populations, such as those prescribed the dopamine agonist pramipexole (PPX). Based on the results of previous studies, it is unclear whether PPX increases rats' impulsive choice or attenuates aspects of stimulus control. The present study was designed to experimentally isolate behavioral processes fundamental to intertemporal choice and challenge them pharmacologically with PPX administration. In Experiment 1, the hypothesis that PPX increases impulsive choice as a result of enhanced sensitivity to reinforcer delays was tested and disconfirmed. That is, acute PPX diminished delay sensitivity in a manner consistent with disruption of stimulus control whereas repeated PPX had no effect on delay sensitivity. Experiments 2 and 3 elaborated upon this finding by examining the effects of repeated PPX on rats' discrimination of response-reinforcer contingencies and reinforcer amounts, respectively. Accuracy of both discriminations was reduced by PPX. Collectively these results provide no support for past studies that have suggested PPX increases impulsive choice. Instead, PPX impairs stimulus control over choice behavior. The behavioral approach adopted herein could be profitably integrated with genetic and other biobehavioral models to advance our understanding of impulsive behavior associated with drug administration. © Society for the Experimental Analysis of Behavior.

The Medial Temporal Lobes are Critical for Reward-Based Decision Making under Conditions that Promote Episodic Future Thinking

PubMed Central

Palombo, Daniela J.; Keane, Margaret M.; Verfaellie, Mieke

2014-01-01

In the present study, we investigated the effect of medial temporal lobe (MTL) damage on human decision making in the context of reward-based intertemporal choice. During intertemporal choice, humans typically devalue (or discount) a future reward to account for its delayed arrival (e.g., preferring $30 now over $42 in 2 months), but this effect is attenuated when participants engage in episodic future thinking, i.e., project themselves into the future to imagine a specific event. We hypothesized that this attenuation would be selectively impaired in amnesic patients, who have deficits in episodic future thinking. Replicating previous work, in a standard intertemporal choice task, amnesic patients showed temporal discounting indices similar to healthy controls. Consistent with our hypothesis, while healthy controls demonstrated attenuated temporal discounting in a condition that required participants first to engage in episodic future thinking (e.g., to imagine spending $42 at a theatre in 2 months), amnesic patients failed to demonstrate this effect. Moreover, as expected, amnesic patients’ narratives were less episodically rich than those of controls. These findings extend the range of tasks that are shown to be MTL dependent to include not only memory-based decision-making tasks but also future-oriented ones. PMID:25284804

Using future thinking to reduce temporal discounting: Under what circumstances are the medial temporal lobes critical?

PubMed

Palombo, D J; Keane, M M; Verfaellie, M

2016-08-01

The capacity to envision the future plays an important role in many aspects of cognition, including our ability to make optimal, adaptive choices. Past work has shown that the medial temporal lobe (MTL) is necessary for decisions that draw on episodic future thinking. By contrast, little is known about the role of the MTL in decisions that draw on semantic future thinking. Accordingly, the present study investigated whether the MTL contributes to one form of decision making, namely intertemporal choice, when such decisions depend on semantic consideration of the future. In an intertemporal choice task, participants must select either a smaller amount of money that is available in the present or a larger amount of money that would be available at a future date. Amnesic individuals with MTL damage and healthy control participants performed such a task in which, prior to making a choice, they engaged in a semantic generation exercise, wherein they generated items that they would purchase with the future reward. In experiment 1, we found that, relative to a baseline condition involving standard intertemporal choice, healthy individuals were more inclined to select a larger, later reward over a smaller, present reward after engaging in semantic future thinking. By contrast, amnesic participants were paradoxically less inclined to wait for a future reward following semantic future thinking. This finding suggests that amnesics may have had difficulty "tagging" the generated item(s) as belonging to the future. Critically, experiment 2 showed that when the generated items were presented alongside the intertemporal choices, both controls and amnesic participants shifted to more patient choices. These findings suggest that the MTL is not needed for making optimal decisions that draw on semantic future thinking as long as scaffolding is provided to support accurate time tagging. Together, these findings stand to better clarify the role of the MTL in decision making. Published by Elsevier Ltd.

Environmental cost-effectiveness analysis in intertemporal natural resource policy: evaluation of selective fishing gear.

PubMed

Kronbak, Lone Grønbæk; Vestergaard, Niels

2013-12-15

In most decision-making involving natural resources, the achievements of a given policy (e.g., improved ecosystem or biodiversity) are rather difficult to measure in monetary units. To address this problem, the current paper develops an environmental cost-effectiveness analysis (ECEA) to include intangible benefits in intertemporal natural resource problems. This approach can assist managers in prioritizing management actions as least cost solutions to achieve quantitative policy targets. The ECEA framework is applied to a selective gear policy case in Danish mixed trawl fisheries in Kattegat and Skagerrak. The empirical analysis demonstrates how a policy with large negative net benefits might be justified if the intangible benefits are included. Copyright © 2013 Elsevier Ltd. All rights reserved.

Individual laboratory-measured discount rates predict field behavior

PubMed Central

Chabris, Christopher F.; Laibson, David; Morris, Carrie L.; Schuldt, Jonathon P.; Taubinsky, Dmitry

2009-01-01

We estimate discount rates of 555 subjects using a laboratory task and find that these individual discount rates predict inter-individual variation in field behaviors (e.g., exercise, BMI, smoking). The correlation between the discount rate and each field behavior is small: none exceeds 0.28 and many are near 0. However, the discount rate has at least as much predictive power as any variable in our dataset (e.g., sex, age, education). The correlation between the discount rate and field behavior rises when field behaviors are aggregated: these correlations range from 0.09-0.38. We present a model that explains why specific intertemporal choice behaviors are only weakly correlated with discount rates, even though discount rates robustly predict aggregates of intertemporal decisions. PMID:19412359

Individual laboratory-measured discount rates predict field behavior.

PubMed

Chabris, Christopher F; Laibson, David; Morris, Carrie L; Schuldt, Jonathon P; Taubinsky, Dmitry

2008-12-01

We estimate discount rates of 555 subjects using a laboratory task and find that these individual discount rates predict inter-individual variation in field behaviors (e.g., exercise, BMI, smoking). The correlation between the discount rate and each field behavior is small: none exceeds 0.28 and many are near 0. However, the discount rate has at least as much predictive power as any variable in our dataset (e.g., sex, age, education). The correlation between the discount rate and field behavior rises when field behaviors are aggregated: these correlations range from 0.09-0.38. We present a model that explains why specific intertemporal choice behaviors are only weakly correlated with discount rates, even though discount rates robustly predict aggregates of intertemporal decisions.

Community trust reduces myopic decisions of low-income individuals

PubMed Central

Jachimowicz, Jon M.; Chafik, Salah; Munrat, Sabeth; Prabhu, Jaideep C.; Weber, Elke U.

2017-01-01

Why do the poor make shortsighted choices in decisions that involve delayed payoffs? Foregoing immediate rewards for larger, later rewards requires that decision makers (i) believe future payoffs will occur and (ii) are not forced to take the immediate reward out of financial need. Low-income individuals may be both less likely to believe future payoffs will occur and less able to forego immediate rewards due to higher financial need; they may thus appear to discount the future more heavily. We propose that trust in one’s community—which, unlike generalized trust, we find does not covary with levels of income—can partially offset the effects of low income on myopic decisions. Specifically, we hypothesize that low-income individuals with higher community trust make less myopic intertemporal decisions because they believe their community will buffer, or cushion, against their financial need. In archival data and laboratory studies, we find that higher levels of community trust among low-income individuals lead to less myopic decisions. We also test our predictions with a 2-y community trust intervention in rural Bangladesh involving 121 union councils (the smallest rural administrative and local government unit) and find that residents in treated union councils show higher levels of community trust and make less myopic intertemporal choices than residents in control union councils. We discuss the implications of these results for the design of domestic and global policy interventions to help the poor make decisions that could alleviate poverty. PMID:28400516

Side Effects in Time Discounting Procedures: Fixed Alternatives Become the Reference Point

PubMed Central

2016-01-01

Typical research on intertemporal choice utilizes a two-alternative forced choice (2AFC) paradigm requiring participants to choose between a smaller sooner and larger later payoff. In the adjusting-amount procedure (AAP) one of the alternatives is fixed and the other is adjusted according to particular choices made by the participant. Such a method makes the alternatives unequal in status and is speculated to make the fixed alternative a reference point for choices, thereby affecting the decision made. The current study shows that fixing different alternatives in the AAP influences discount rates in intertemporal choices. Specifically, individuals’ (N = 283) choices were affected to just the same extent by merely fixing an alternative as when choices were preceded by scenarios explicitly imposing reference points. PMID:27768759

Standing in Your Peer’s Shoes Hurts Your Feats: The Self-Others Discrepancy in Risk Attitude and Impulsivity

PubMed Central

Białaszek, Wojciech; Bakun, Piotr; McGoun, Elton; Zielonka, Piotr

2016-01-01

It is often a good strategy to “stand in the other person’s shoes” to see a situation from a different perspective. People frequently attempt to infer what someone else would recommend when no advisor is available to help with a decision. Such situations commonly concern intertemporal or risky choices, and the usual assumption is that lay people make such decisions differently than experts do. The aim of our study was to determine what intertemporal and risky decisions people make when they take their own perspective, the perspective of a peer, and the perspectives of an expert or an entrepreneur. In a series of three experiments using a between-subject design, we found that taking the peer’s perspective made participants behave more impulsively and more risk aversely in relation to the participants’ own perspectives and in relation to their perceptions of experts and entrepreneurs perspectives. Taking an expert’s or an entrepreneur’s perspective did not change participants’ own intertemporal and risky decisions. We explain the findings using the risk as value and the lesser mind theories. Imagining the opponent’s perspective in a negotiation as one is advised to do might inadvertently lead to problems because we always see her as more impulsive and more risk averse than she really is. This means that taking a perspective of an expert – not a peer – would be a good way to predict what decisions our opponents make. PMID:26925015

A potential role of reward and punishment in the facilitation of the emotion-cognition dichotomy in the Iowa Gambling Task.

PubMed

Singh, Varsha

2013-01-01

The Iowa Gambling Task (IGT) is based on the assumption that a decision maker is equally motivated to seek reward and avoid punishment, and that decision making is governed solely by the intertemporal attribute (i.e., preference for an option that produces an immediate outcome instead of one that yields a delayed outcome is believed to reflect risky decision making and is considered a deficit). It was assumed in the present study that the emotion- and cognition-based processing dichotomy manifests in the IGT as reward and punishment frequency and the intertemporal attribute. It was further proposed that the delineation of emotion- and cognition-based processing is contingent upon reward and punishment as manifested in the frame of the task (variant type) and task motivation (instruction type). The effects of IGT variant type (reward vs. punishment) and instruction type (task motivation induced by instruction types: reward, punishment, reward and punishment, or no hint) on the intertemporal and frequency attributes of IGT decision-making were analyzed. Decision making in the reward variant was equally governed by both attributes, and significantly affected by instruction type, while decision making in the punishment variant was differentially affected by the two attributes and not significantly impacted by instruction type. These results suggest that reward and punishment manifested via task frame as well as the task motivation may facilitate the differentiation of emotion- and cognition-based processing in the IGT.

A potential role of reward and punishment in the facilitation of the emotion-cognition dichotomy in the Iowa Gambling Task

PubMed Central

Singh, Varsha

2013-01-01

The Iowa Gambling Task (IGT) is based on the assumption that a decision maker is equally motivated to seek reward and avoid punishment, and that decision making is governed solely by the intertemporal attribute (i.e., preference for an option that produces an immediate outcome instead of one that yields a delayed outcome is believed to reflect risky decision making and is considered a deficit). It was assumed in the present study that the emotion- and cognition-based processing dichotomy manifests in the IGT as reward and punishment frequency and the intertemporal attribute. It was further proposed that the delineation of emotion- and cognition-based processing is contingent upon reward and punishment as manifested in the frame of the task (variant type) and task motivation (instruction type). The effects of IGT variant type (reward vs. punishment) and instruction type (task motivation induced by instruction types: reward, punishment, reward and punishment, or no hint) on the intertemporal and frequency attributes of IGT decision-making were analyzed. Decision making in the reward variant was equally governed by both attributes, and significantly affected by instruction type, while decision making in the punishment variant was differentially affected by the two attributes and not significantly impacted by instruction type. These results suggest that reward and punishment manifested via task frame as well as the task motivation may facilitate the differentiation of emotion- and cognition-based processing in the IGT. PMID:24381567

Auxiliary principle technique and iterative algorithm for a perturbed system of generalized multi-valued mixed quasi-equilibrium-like problems.

PubMed

Rahaman, Mijanur; Pang, Chin-Tzong; Ishtyak, Mohd; Ahmad, Rais

2017-01-01

In this article, we introduce a perturbed system of generalized mixed quasi-equilibrium-like problems involving multi-valued mappings in Hilbert spaces. To calculate the approximate solutions of the perturbed system of generalized multi-valued mixed quasi-equilibrium-like problems, firstly we develop a perturbed system of auxiliary generalized multi-valued mixed quasi-equilibrium-like problems, and then by using the celebrated Fan-KKM technique, we establish the existence and uniqueness of solutions of the perturbed system of auxiliary generalized multi-valued mixed quasi-equilibrium-like problems. By deploying an auxiliary principle technique and an existence result, we formulate an iterative algorithm for solving the perturbed system of generalized multi-valued mixed quasi-equilibrium-like problems. Lastly, we study the strong convergence analysis of the proposed iterative sequences under monotonicity and some mild conditions. These results are new and generalize some known results in this field.

Exploring Chemical Equilibrium with Poker Chips: A General Chemistry Laboratory Exercise

ERIC Educational Resources Information Center

Bindel, Thomas H.

2012-01-01

A hands-on laboratory exercise at the general chemistry level introduces students to chemical equilibrium through a simulation that uses poker chips and rate equations. More specifically, the exercise allows students to explore reaction tables, dynamic chemical equilibrium, equilibrium constant expressions, and the equilibrium constant based on…

Measuring Impatience in Intertemporal Choice.

PubMed

Cruz Rambaud, Salvador; Muñoz Torrecillas, María José

2016-01-01

In general terms, decreasing impatience means decreasing discount rates. This property has been usually referred to as hyperbolic discounting, although there are other discount functions which also exhibit decreasing discount rates. This paper focuses on the measurement of the impatience associated with a discount function with the aim of establishing a methodology to compare this characteristic for two different discount functions. In this way, first we define the patience associated with a discount function in an interval as its corresponding discount factor and consequently we deduce that the impatience at a given moment is the corresponding instantaneous discount rate. Second we compare the degree of impatience of discount functions belonging to the same or different families, by considering the cases in which the functions do or do not intersect.

An intertemporal decision framework for electrochemical energy storage management

NASA Astrophysics Data System (ADS)

He, Guannan; Chen, Qixin; Moutis, Panayiotis; Kar, Soummya; Whitacre, Jay F.

2018-05-01

Dispatchable energy storage is necessary to enable renewable-based power systems that have zero or very low carbon emissions. The inherent degradation behaviour of electrochemical energy storage (EES) is a major concern for both EES operational decisions and EES economic assessments. Here, we propose a decision framework that addresses the intertemporal trade-offs in terms of EES degradation by deriving, implementing and optimizing two metrics: the marginal benefit of usage and the average benefit of usage. These metrics are independent of the capital cost of the EES system, and, as such, separate the value of EES use from the initial cost, which provides a different perspective on storage valuation and operation. Our framework is proved to produce the optimal solution for EES life-cycle profit maximization. We show that the proposed framework offers effective ways to assess the economic values of EES, to make investment decisions for various applications and to inform related subsidy policies.

Effect of emotional arousal on inter-temporal decision-making: an fMRI study.

PubMed

Sohn, Jin-Hun; Kim, Hyo-Eun; Sohn, Sunju; Seok, Ji-Woo; Choi, Damee; Watanuki, Shigeki

2015-03-07

Previous research has shown that emotion can significantly impact decision-making in humans. The current study examined whether or not and how situationally induced emotion influences people to make inter-temporal choices. Affective pictures were used as experiment stimuli to provoke emotion, immediately followed by subjects' performance of a delay-discounting task to measure impulsivity during functional magnetic resonance imaging. Results demonstrate a subsequent process of increased impulsive decision-making following a prior exposure to both high positive and negative arousal stimuli, compared to the experiment subjects' experiences with neutral stimuli. Findings indicate that increased impulsive decision-making behaviors can occur with high arousal and can be characterized by decreased activities in the cognitive control regions such as prefronto-parietal regions. These results suggest that 'stabilization of high emotional arousal' may facilitate a reduction of impulsive decision-making and implementation of longer term goals.

Paralimbic and lateral prefrontal encoding of reward value during intertemporal choice in attempted suicide.

PubMed

Vanyukov, P M; Szanto, K; Hallquist, M N; Siegle, G J; Reynolds, C F; Forman, S D; Aizenstein, H J; Dombrovski, A Y

2016-01-01

Alongside impulsive suicide attempts, clinicians encounter highly premeditated suicidal acts, particularly in older adults. We have previously found that in contrast to the more impulsive suicide attempters' inability to delay gratification, serious and highly planned suicide attempts were associated with greater willingness to wait for larger rewards. This study examined neural underpinnings of intertemporal preference in suicide attempters. We expected that impulsivity and suicide attempts, particularly poorly planned ones, would predict altered paralimbic subjective value representations. We also examined lateral prefrontal and paralimbic correlates of premeditation in suicidal behavior. A total of 48 participants aged 46-90 years underwent extensive clinical and cognitive characterization and completed the delay discounting task in the scanner: 26 individuals with major depression (13 with and 13 without history of suicide attempts) and 22 healthy controls. More impulsive individuals displayed greater activation in the precuneus/posterior cingulate cortex (PCC) to value difference favoring the delayed option. Suicide attempts, particularly better-planned ones, were associated with deactivation of the lateral prefrontal cortex (lPFC) in response to value difference favoring the immediate option. Findings were robust to medication exposure, depression severity and possible brain damage from suicide attempts, among other confounders. Finally, in suicide attempters longer reward delays were associated with diminished parahippocampal responses. Impulsivity was associated with an altered paralimbic (precuneus/PCC) encoding of value difference during intertemporal choice. By contrast, better-planned suicidal acts were associated with altered lPFC representations of value difference. The study provides preliminary evidence of impaired decision processes in both impulsive and premeditated suicidal behavior.

Forest and Agricultural Sector Optimization Model Greenhouse Gas Version (FASOM-GHG)

EPA Science Inventory

FASOM-GHG is a dynamic, multi-period, intertemporal, price-endogenous, mathematical programming model depicting land transfers and other resource allocations between and within the agricultural and forest sectors in the US. The model solution portrays simultaneous market equilibr...

The Gibbs Variational Method in Thermodynamics of Equilibrium Plasma: 1. General Conditions of Equilibrium and Stability for One-Component Charged Gas

DTIC Science & Technology

2018-04-01

systems containing ionized gases. 2. Gibbs Method in the Integral Form As per the Gibbs general methodology , based on the concept of heterogeneous...ARL-TR-8348 ● APR 2018 US Army Research Laboratory The Gibbs Variational Method in Thermodynamics of Equilibrium Plasma: 1...ARL-TR-8348 ● APR 2018 US Army Research Laboratory The Gibbs Variational Method in Thermodynamics of Equilibrium Plasma: 1. General

Artificial equilibrium points for a generalized sail in the elliptic restricted three-body problem

NASA Astrophysics Data System (ADS)

Aliasi, Generoso; Mengali, Giovanni; Quarta, Alessandro A.

2012-10-01

Different types of propulsion systems with continuous and purely radial thrust, whose modulus depends on the distance from a massive body, may be conveniently described within a single mathematical model by means of the concept of generalized sail. This paper discusses the existence and stability of artificial equilibrium points maintained by a generalized sail within an elliptic restricted three-body problem. Similar to the classical case in the absence of thrust, a generalized sail guarantees the existence of equilibrium points belonging only to the orbital plane of the two primaries. The geometrical loci of existing artificial equilibrium points are shown to coincide with those obtained for the circular three body problem when a non-uniformly rotating and pulsating coordinate system is chosen to describe the spacecraft motion. However, the generalized sail has to provide a periodically variable acceleration to maintain a given artificial equilibrium point. A linear stability analysis of the artificial equilibrium points is provided by means of the Floquet theory.

Description of the General Equilibrium Model of Ecosystem Services (GEMES)

Treesearch

Travis Warziniack; David Finnoff; Jenny Apriesnig

2017-01-01

This paper serves as documentation for the General Equilibrium Model of Ecosystem Services (GEMES). GEMES is a regional computable general equilibrium model that is composed of values derived from natural capital and ecosystem services. It models households, producing sectors, and governments, linked to one another through commodity and factor markets. GEMES was...

Measuring Impatience in Intertemporal Choice

PubMed Central

2016-01-01

In general terms, decreasing impatience means decreasing discount rates. This property has been usually referred to as hyperbolic discounting, although there are other discount functions which also exhibit decreasing discount rates. This paper focuses on the measurement of the impatience associated with a discount function with the aim of establishing a methodology to compare this characteristic for two different discount functions. In this way, first we define the patience associated with a discount function in an interval as its corresponding discount factor and consequently we deduce that the impatience at a given moment is the corresponding instantaneous discount rate. Second we compare the degree of impatience of discount functions belonging to the same or different families, by considering the cases in which the functions do or do not intersect. PMID:26890895

Intertemporal Choice Behavior in Emerging Adults and Adults: Effects of Age Interact with Alcohol Use and Family History Status

PubMed Central

Smith, Christopher T.; Steel, Eleanor A.; Parrish, Michael H.; Kelm, Mary K.; Boettiger, Charlotte A.

2015-01-01

Adults with alcohol use disorders (AUDs) show marked immediate reward selection (or “Now”) bias in intertemporal choice tasks. This Now bias persists long into abstinence, suggesting an irreversible consequence of chronic alcohol abuse or a pre-existing AUD intermediate phenotype. However, some data show substantial Now bias among emerging adults (18–25), regardless of drinking behavior, suggesting age-dependent effects on Now bias. The objectives of the present study were to determine (1) whether Now bias is greater among emerging adults relative to adults, (2) whether any such age effect on Now bias is diminished in sub-clinical heavy alcohol users, and (3) whether having a problem drinking first degree relative is independently associated with elevated Now bias. To achieve these objectives, we used an intertemporal choice task to quantify Now bias in n = 237 healthy participants (ages 18–40; 50% female), and a wide range of non-zero alcohol use, based on the Alcohol Use Disorders Identification Test (AUDIT). We found that among non-heavy drinkers, Now bias inversely correlated with age; this relationship was not present among heavy drinkers. We found no significant relationship between AUDIT score and Now bias among emerging adults, but AUDIT scores and Now bias were positively correlated among 26–40 year olds. Additionally, non-heavy drinking adults who reported a problem drinking first degree relative showed greater Now bias compared to those not reporting familial problem drinking. While not definitive, these findings lend support for elevated Now bias in adulthood as an intermediate phenotype for AUDs. Moreover, non-additive effects of age and heavy drinking on Now bias suggest perturbations in largely common neural circuits in both groups. PMID:26635580

Bringing the Biosphere Home.

ERIC Educational Resources Information Center

Thomashow, Mitchell

2002-01-01

Discusses an orientation to the local environment as the lens through which to detect global change. Discusses how students can relate to a structure that includes the intertemporal, interspatial, intergenerational, and interspecies realities of place leading to a comprehensive view of biology. Discusses the existential tensions intrinsic to…

Future self-continuity: how conceptions of the future self transform intertemporal choice

PubMed Central

Hershfield, Hal E.

2013-01-01

With life expectancy dramatically increasing throughout much of the world, people have to make choices with a longer future in mind than they ever had to before. Yet, many indicators suggest that undersaving for the long term often occurs: in America, for instance, many individuals will not be able to maintain their preretirement standard of living in retirement. Previous research has tried to understand problems with intertemporal choice by focusing on the ways in which people treat present and future rewards. In this paper, the author reviews a burgeoning body of theoretical and empirical work that takes a different viewpoint, one that focuses on how perceptions of the self over time can dramatically affect decision making. Specifically, when the future self shares similarities with the present self, when it is viewed in vivid and realistic terms, and when it is seen in a positive light, people are more willing to make choices today that may benefit them at some point in the years to come. PMID:22023566

Dorsal Raphe Serotonergic Neurons Control Intertemporal Choice under Trade-off.

PubMed

Xu, Sangyu; Das, Gishnu; Hueske, Emily; Tonegawa, Susumu

2017-10-23

Appropriate choice about delayed reward is fundamental to the survival of animals. Although animals tend to prefer immediate reward, delaying gratification is often advantageous. The dorsal raphe (DR) serotonergic neurons have long been implicated in the processing of delayed reward, but it has been unclear whether or when their activity causally directs choice. Here, we transiently augmented or reduced the activity of DR serotonergic neurons, while mice decided between differently delayed rewards as they performed a novel odor-guided intertemporal choice task. We found that these manipulations, precisely targeted at the decision point, were sufficient to bidirectionally influence impulsive choice. The manipulation specifically affected choices with more difficult trade-off. Similar effects were observed when we manipulated the serotonergic projections to the nucleus accumbens (NAc). We propose that DR serotonergic neurons preempt reward delays at the decision point and play a critical role in suppressing impulsive choice by regulating decision trade-off. Copyright © 2017 Elsevier Ltd. All rights reserved.

The financial costs of sadness.

PubMed

Lerner, Jennifer S; Li, Ye; Weber, Elke U

2013-01-01

We hypothesized a phenomenon that we term myopic misery. According to our hypothesis, sadness increases impatience and creates a myopic focus on obtaining money immediately instead of later. This focus, in turn, increases intertemporal discount rates and thereby produces substantial financial costs. In three experiments, we randomly assigned participants to sad- and neutral-state conditions, and then offered intertemporal choices. Disgust served as a comparison condition in Experiments 1 and 2. Sadness significantly increased impatience: Relative to median neutral-state participants, median sad-state participants accepted 13% to 34% less money immediately to avoid waiting 3 months for payment. In Experiment 2, impatient thoughts mediated the effects. Experiment 3 revealed that sadness made people more present biased (i.e., wanting something immediately), but not globally more impatient. Disgusted participants were not more impatient than neutral participants, and that lack of difference implies that the same financial effects do not arise from all negative emotions. These results show that myopic misery is a robust and potentially harmful phenomenon.

Sweet sixteen: changing time preferences in the transition from middle school to high school, for different scenarios.

PubMed

Lahav, Eyal; Shavit, Tal; Benzion, Uri

2015-01-01

Teenagers earn, save and spend large amounts of money. Therefore, understanding teenagers' time preference and how it affects their economic behavior is very important. The current study investigates time preferences of high school and middle school students, and the effect of different intertemporal choice scenarios on teenagers' subjective discount rate. One scenario used a standard intertemporal choice question while the other was a wage scenario. We found higher future orientation (lower subjective discount rate) among high school students than among middle school students when using a standard scenario but found no difference between groups in the wage scenario. For both groups, we found the subjective discount rates increased when the teenagers are asked to delay receipt of wages they earned by working (wage scenario). Other variables, like participation in sports and an allowance given by parents, were found to affect teenagers' time preferences. © Society for the Experimental Analysis of Behavior.

Errors as a Means of Reducing Impulsive Food Choice.

PubMed

Sellitto, Manuela; di Pellegrino, Giuseppe

2016-06-05

Nowadays, the increasing incidence of eating disorders due to poor self-control has given rise to increased obesity and other chronic weight problems, and ultimately, to reduced life expectancy. The capacity to refrain from automatic responses is usually high in situations in which making errors is highly likely. The protocol described here aims at reducing imprudent preference in women during hypothetical intertemporal choices about appetitive food by associating it with errors. First, participants undergo an error task where two different edible stimuli are associated with two different error likelihoods (high and low). Second, they make intertemporal choices about the two edible stimuli, separately. As a result, this method decreases the discount rate for future amounts of the edible reward that cued higher error likelihood, selectively. This effect is under the influence of the self-reported hunger level. The present protocol demonstrates that errors, well known as motivationally salient events, can induce the recruitment of cognitive control, thus being ultimately useful in reducing impatient choices for edible commodities.

Errors as a Means of Reducing Impulsive Food Choice

PubMed Central

Sellitto, Manuela; di Pellegrino, Giuseppe

2016-01-01

Nowadays, the increasing incidence of eating disorders due to poor self-control has given rise to increased obesity and other chronic weight problems, and ultimately, to reduced life expectancy. The capacity to refrain from automatic responses is usually high in situations in which making errors is highly likely. The protocol described here aims at reducing imprudent preference in women during hypothetical intertemporal choices about appetitive food by associating it with errors. First, participants undergo an error task where two different edible stimuli are associated with two different error likelihoods (high and low). Second, they make intertemporal choices about the two edible stimuli, separately. As a result, this method decreases the discount rate for future amounts of the edible reward that cued higher error likelihood, selectively. This effect is under the influence of the self-reported hunger level. The present protocol demonstrates that errors, well known as motivationally salient events, can induce the recruitment of cognitive control, thus being ultimately useful in reducing impatient choices for edible commodities. PMID:27341281

Neural congruence between intertemporal and interpersonal self-control: Evidence from delay and social discounting.

PubMed

Hill, Paul F; Yi, Richard; Spreng, R Nathan; Diana, Rachel A

2017-11-15

Behavioral studies using delay and social discounting as indices of self-control and altruism, respectively, have revealed functional similarities between farsighted and social decisions. However, neural evidence for this functional link is lacking. Twenty-five young adults completed a delay and social discounting task during fMRI scanning. A spatiotemporal partial least squares analysis revealed that both forms of discounting were well characterized by a pattern of brain activity in areas comprising frontoparietal control, default, and mesolimbic reward networks. Both forms of discounting appear to draw on common neurocognitive mechanisms, regardless of whether choices involve intertemporal or interpersonal outcomes. We also observed neural profiles differentiating between high and low discounters. High discounters were well characterized by increased medial temporal lobe and limbic activity. In contrast, low discount rates were associated with activity in the medial prefrontal cortex and right temporoparietal junction. This pattern may reflect biological mechanisms underlying behavioral heterogeneity in discount rates. Copyright © 2017 Elsevier Inc. All rights reserved.

Generalized non-equilibrium vertex correction method in coherent medium theory for quantum transport simulation of disordered nanoelectronics

NASA Astrophysics Data System (ADS)

Yan, Jiawei; Ke, Youqi

In realistic nanoelectronics, disordered impurities/defects are inevitable and play important roles in electron transport. However, due to the lack of effective quantum transport method, the important effects of disorders remain poorly understood. Here, we report a generalized non-equilibrium vertex correction (NVC) method with coherent potential approximation to treat the disorder effects in quantum transport simulation. With this generalized NVC method, any averaged product of two single-particle Green's functions can be obtained by solving a set of simple linear equations. As a result, the averaged non-equilibrium density matrix and various important transport properties, including averaged current, disordered induced current fluctuation and the averaged shot noise, can all be efficiently computed in a unified scheme. Moreover, a generalized form of conditionally averaged non-equilibrium Green's function is derived to incorporate with density functional theory to enable first-principles simulation. We prove the non-equilibrium coherent potential equals the non-equilibrium vertex correction. Our approach provides a unified, efficient and self-consistent method for simulating non-equilibrium quantum transport through disorder nanoelectronics. Shanghaitech start-up fund.

Chemical Principles Revisited: Chemical Equilibrium.

ERIC Educational Resources Information Center

Mickey, Charles D.

1980-01-01

Describes: (1) Law of Mass Action; (2) equilibrium constant and ideal behavior; (3) general form of the equilibrium constant; (4) forward and reverse reactions; (5) factors influencing equilibrium; (6) Le Chatelier's principle; (7) effects of temperature, changing concentration, and pressure on equilibrium; and (8) catalysts and equilibrium. (JN)

Time Horizons, Discounting, and Intertemporal Choice

ERIC Educational Resources Information Center

Streich, Philip; Levy, Jack S.

2007-01-01

Although many decisions involve a stream of payoffs over time, political scientists have given little attention to how actors make the required tradeoffs between present and future payoffs, other than applying the standard exponential discounting model from economics. After summarizing the basic discounting model, we identify some of its leading…

A Better Budget Rule

ERIC Educational Resources Information Center

Dothan, Michael; Thompson, Fred

2009-01-01

Debt limits, interest coverage ratios, one-off balanced budget requirements, pay-as-you-go rules, and tax and expenditure limits are among the most important fiscal rules for constraining intertemporal transfers. There is considerable evidence that the least costly and most effective of such rules are those that focus directly on the rate of…

Housing Uncertainty and Childhood Impatience

ERIC Educational Resources Information Center

Anil, Bulent; Jordan, Jeffrey L.; Zahirovic-Herbert, Velma

2011-01-01

The study demonstrates a direct link between housing uncertainty and children's time preferences, or patience. We show that students who face housing uncertainties through mortgage foreclosures and eviction learn impatient behavior and are therefore at greater risk of making poor intertemporal choices such as dropping out of school. We find that…

General stochastic variational formulation for the oligopolistic market equilibrium problem with excesses

NASA Astrophysics Data System (ADS)

Barbagallo, Annamaria; Di Meglio, Guglielmo; Mauro, Paolo

2017-07-01

The aim of the paper is to study, in a Hilbert space setting, a general random oligopolistic market equilibrium problem in presence of both production and demand excesses and to characterize the random Cournot-Nash equilibrium principle by means of a stochastic variational inequality. Some existence results are presented.

Resource linkages and sustainable development

NASA Astrophysics Data System (ADS)

Anouti, Yahya

Historically, fossil fuel consumers in most developing hydrocarbon-rich countries have enjoyed retail prices at a discount from international benchmarks. Governments of these countries consider the subsidy transfer to be a means for sharing the wealth from their resource endowment. These subsidies create negative economic, environmental, and social distortions, which can only increase over time with a fast growing, young, and rich population. The pressure to phase out these subsidies has been mounting over the last years. At the same time, policy makers in resource-rich developing countries are keen to obtain the greatest benefits for their economies from the extraction of their exhaustible resources. To this end, they are deploying local content policies with the aim of increasing the economic linkages from extracting their resources. Against this background, this dissertation's three essays evaluate (1) the global impact of rationalizing transport fuel prices, (2) how resource-rich countries can achieve the objectives behind fuel subsidies more efficiently through direct cash transfers, and (3) the economic tradeoffs from deploying local content policies and the presence of an optimal path. We begin by reviewing the literature and building the case for rationalizing transport fuel prices to reflect their direct costs (production), indirect costs (road maintenance) and negative externalities (climate change, local pollutants, traffic accidents and congestion). To do so, we increase the scope of the economic literature by presenting an algorithm to evaluate the rationalized prices in different countries. Then, we apply this algorithm to quantify the rationalized prices across 123 countries in a partial equilibrium setting. Finally, we present the first comprehensive measure of the impact of rationalizing fuel prices on the global demand for gasoline and diesel, environmental emissions, government revenues, and consumers' welfare. By rationalizing transport fuel prices we estimate that the demand for gasoline could be reduced by 7.8 percent and that of diesel by 5.9 percent. This would lead to not only reduction in the associated negative externalities, but also to the generation of more than USD400 billion in revenues for governments. However, the partial equilibrium analysis in essay one ignores the general equilibrium effects that will be mainly driven by how the government spends the subsidy. In essay 2, we build the case for phasing out these subsidies and accompanying that by a welfare compensating cash transfer. In order to evaluate the impact of that on consumer's welfare, we develop a numerical model for Saudi Arabia in a general equilibrium setting to discuss a phase out of transport fuel subsidies that is. Results show that the Saudi government can increase its consumers' welfare up to five percentage points. In case the cash transfer is adjusted to keep consumers' utility at the pre-reform level, the required compensating transfer would leave the government with three percentage points of additional revenues. Finally, we highlight policy implications of phasing out the transport fuel subsidies. Finally, in essay 3 we turn our focus to the application of local content policies in the oil and gas sector. There is limited literature that investigates economic linkages from the extractive industries, assesses intertemporal tradeoffs, and guides the design of efficient and sustainable policies. Our contribution in this essay is three-fold. First, we present the first comprehensive analysis of economic linkages from the oil and gas sector across 48 countries. Then, we analyze the economic distortions from applying local content policies using a Hotelling type optimal control model with an international oil company maximizing its profits subject to a local content requirement. Finally, we investigate the presence of a socially optimal local content level when the social planner maximizing the net benefits from the extraction of resources. The social planner is presented with social objectives and a learning curve that are not internalized by the international oil companies. Findings reveal that in presence of (1) social benefits from using domestic input or (2) learning curve effects, there exists an optimal local content path that increases with cumulative production.

On the Empirical Importance of the Conditional Skewness Assumption in Modelling the Relationship between Risk and Return

NASA Astrophysics Data System (ADS)

Pipień, M.

2008-09-01

We present the results of an application of Bayesian inference in testing the relation between risk and return on the financial instruments. On the basis of the Intertemporal Capital Asset Pricing Model, proposed by Merton we built a general sampling distribution suitable in analysing this relationship. The most important feature of our assumptions is that the skewness of the conditional distribution of returns is used as an alternative source of relation between risk and return. This general specification relates to Skewed Generalized Autoregressive Conditionally Heteroscedastic-in-Mean model. In order to make conditional distribution of financial returns skewed we considered the unified approach based on the inverse probability integral transformation. In particular, we applied hidden truncation mechanism, inverse scale factors, order statistics concept, Beta and Bernstein distribution transformations and also a constructive method. Based on the daily excess returns on the Warsaw Stock Exchange Index we checked the empirical importance of the conditional skewness assumption on the relation between risk and return on the Warsaw Stock Market. We present posterior probabilities of all competing specifications as well as the posterior analysis of the positive sign of the tested relationship.

Effect of a Perturbation on the Chemical Equilibrium: Comparison with Le Chatelier's Principle

ERIC Educational Resources Information Center

Torres, Emilio Martinez

2007-01-01

This article develops a general thermodynamic treatment to predict the direction of shift in a chemical equilibrium when it is subjected to a stress. This treatment gives an inequality that relates the change in the perturbed variable and the change that the equilibrium shift produces in the conjugated variable. To illustrate the generality of…

Investment in Human Capital. Schooling Supply Constraints in Rural Ghana.

ERIC Educational Resources Information Center

Lavy, Victor

This paper hypothesizes that the cost differential between primary school and middle or secondary schooling will affect household decisions to invest in any one schooling level in Ghana. Human capital investment is usually modeled in an intertemporal optimization framework in which households or individuals maximize the present value of life-time…

Unequal Education, Poverty and Low Growth--A Theoretical Framework for Rural Education of China

ERIC Educational Resources Information Center

Wu, Fangwei; Zhang, Deyuan; Zhang, Jinghua

2008-01-01

This paper constructs an intertemporal substitution educational model based on endogenous growth theory and examines the rural education, farmer income and rural economic growth problems in China. It shows that the households originally with the same economic endowment but different education endowment take different growth routes, the income…

Neural and Behavioral Evidence for a Link between Mobile Technology Engagement and Intertemporal Preference

ERIC Educational Resources Information Center

Wilmer, Henry H.

2017-01-01

Mobile electronic devices such as smartphones are playing an increasingly pervasive role in our daily activities. A growing body of literature is beginning to investigate how mobile technology habits might relate to individual differences in cognitive traits. The present study is an investigation into how individual differences in intertemporal…

Comparative dynamics in a health investment model.

PubMed

Eisenring, C

1999-10-01

The method of comparative dynamics fully exploits the inter-temporal structure of optimal control models. I derive comparative dynamic results in a simplified demand for health model. The effect of a change in the depreciation rate on the optimal paths for health capital and investment in health is studied by use of a phase diagram.

The Reliability, Impact, and Cost-Effectiveness of Value-Added Teacher Assessment Methods

ERIC Educational Resources Information Center

Yeh, Stuart S.

2012-01-01

This article reviews evidence regarding the intertemporal reliability of teacher rankings based on value-added methods. Value-added methods exhibit low reliability, yet are broadly supported by prominent educational researchers and are increasingly being used to evaluate and fire teachers. The article then presents a cost-effectiveness analysis…

The Inter-Temporal Aspect of Well-Being and Societal Progress

ERIC Educational Resources Information Center

Sicherl, Pavle

2007-01-01

The perceptions on well-being and societal progress are influenced also by the quantitative indicators and measures used in the measurement, presentation and semantics of discussing these issues. The article presents a novel generic statistical measure S-time-distance, with clear interpretability that delivers a broader concept to look at data, to…

Intertemporal Regulatory Tasks and Responsibilities for Greenhouse Gas Reductions

ERIC Educational Resources Information Center

Deason, Jeffrey A.; Friedman, Lee S.

2010-01-01

Jurisdictions are in the process of establishing regulatory systems to control greenhouse gas emissions. Short-term and sometimes long-term emissions reduction goals are established, as California does for 2020 and 2050, but little attention has yet been focused on annual emissions targets for the intervening years. We develop recommendations for…

Deriving the Dividend Discount Model in the Intermediate Microeconomics Class

ERIC Educational Resources Information Center

Norman, Stephen; Schlaudraff, Jonathan; White, Karianne; Wills, Douglas

2013-01-01

In this article, the authors show that the dividend discount model can be derived using the basic intertemporal consumption model that is introduced in a typical intermediate microeconomics course. This result will be of use to instructors who teach microeconomics to finance students in that it demonstrates the value of utility maximization in…

The impact of discount rate and price on intertemporal groundwater models in southwest Kansas

USDA-ARS?s Scientific Manuscript database

Agriculture plays a vital role in the growth and development of the High Plains Region of the United States. With the development and adoption of irrigation technology, this region was transformed into one of the most agriculturally productive regions in the world [1]. The primary source of irrigati...

Introducing Valuation Effects-Based External Balance Analysis into the Undergraduate Macroeconomics Curricula: A Simple Framework with Applications

ERIC Educational Resources Information Center

Brust, Peter; Jayakumar, Vivekanand

2012-01-01

Global imbalances and the sustainability of large U.S. current account deficits have dominated international macroeconomics of late. Pedagogically, a clear disconnect exists between graduate-level open-economy macroeconomics that emphasizes intertemporal current account models and net foreign asset adjustment featuring valuation effects, and,…

Posttraumatic Stress Disorder Increases Sensitivity to Long Term Losses among Patients with Major Depressive Disorder

PubMed Central

Vaughan, Christopher; Paulus, Martin P.; Dunlop, Boadie W.

2013-01-01

Background Decisions under risk and with outcomes that are delayed in time are ubiquitous in real life and can have a significant impact on the health and wealth of the decision-maker. Despite its potential relevance for real-world choices, the degree of aberrant risky and intertemporal decision-making in patients suffering from major depressive disorder (MDD) and posttraumatic stress disorder (PTSD) has received little attention to date. Method We used a case-control design to compare decision-making in healthy control subjects (N=16) versus untreated depressed subjects in a current major depressive episode (N=20). In order to examine how major depressive disorder (MDD) may impact decision-making, subjects made decisions over (1) risky outcomes and (2) delayed outcomes in the domain of gains and losses using choice paradigms from neuroeconomics. In a pre-planned analysis, depressed subjects were subdivided into those with primary PTSD along with comorbid MDD (MDD+PTSD) versus those with primary MDD without PTSD (MDD-only). Choice behavior was modeled via a standard econometric model of intertemporal choice, a quasi-hyperbolic temporal discounting function, which was estimated for each subject group separately. Results Under conditions of potential gain, depressed subjects demonstrated greater discounting for gains across all time frames compared to controls. In the realm of losses, both subgroups of depressed subjects discounted more steeply than controls for short time frames. However, for delayed losses ranging from >1-10 years, MDD+PTSD subjects showed shallower discounting rates relative to MDD-only subjects, who continued to discount future losses steeply. Risk attitudes did not contribute to differences in intertemporal choice. Conclusions Depressed patients make choices that minimize current pain and maximize current reward, despite severe later consequences or lost opportunities. Anxiety associated with PTSD may serve as a partially protective factor in decision-making about long-term potential losses compared to MDD patients without PTSD. PMID:24116235

Posttraumatic stress disorder increases sensitivity to long term losses among patients with major depressive disorder.

PubMed

Engelmann, Jan B; Maciuba, Britta; Vaughan, Christopher; Paulus, Martin P; Dunlop, Boadie W

2013-01-01

Decisions under risk and with outcomes that are delayed in time are ubiquitous in real life and can have a significant impact on the health and wealth of the decision-maker. Despite its potential relevance for real-world choices, the degree of aberrant risky and intertemporal decision-making in patients suffering from major depressive disorder (MDD) and posttraumatic stress disorder (PTSD) has received little attention to date. We used a case-control design to compare decision-making in healthy control subjects (N=16) versus untreated depressed subjects in a current major depressive episode (N=20). In order to examine how major depressive disorder (MDD) may impact decision-making, subjects made decisions over (1) risky outcomes and (2) delayed outcomes in the domain of gains and losses using choice paradigms from neuroeconomics. In a pre-planned analysis, depressed subjects were subdivided into those with primary PTSD along with comorbid MDD (MDD+PTSD) versus those with primary MDD without PTSD (MDD-only). Choice behavior was modeled via a standard econometric model of intertemporal choice, a quasi-hyperbolic temporal discounting function, which was estimated for each subject group separately. Under conditions of potential gain, depressed subjects demonstrated greater discounting for gains across all time frames compared to controls. In the realm of losses, both subgroups of depressed subjects discounted more steeply than controls for short time frames. However, for delayed losses ranging from >1-10 years, MDD+PTSD subjects showed shallower discounting rates relative to MDD-only subjects, who continued to discount future losses steeply. Risk attitudes did not contribute to differences in intertemporal choice. Depressed patients make choices that minimize current pain and maximize current reward, despite severe later consequences or lost opportunities. Anxiety associated with PTSD may serve as a partially protective factor in decision-making about long-term potential losses compared to MDD patients without PTSD.

Led into temptation? Rewarding brand logos bias the neural encoding of incidental economic decisions.

PubMed

Murawski, Carsten; Harris, Philip G; Bode, Stefan; Domínguez D, Juan F; Egan, Gary F

2012-01-01

Human decision-making is driven by subjective values assigned to alternative choice options. These valuations are based on reward cues. It is unknown, however, whether complex reward cues, such as brand logos, may bias the neural encoding of subjective value in unrelated decisions. In this functional magnetic resonance imaging (fMRI) study, we subliminally presented brand logos preceding intertemporal choices. We demonstrated that priming biased participants' preferences towards more immediate rewards in the subsequent temporal discounting task. This was associated with modulations of the neural encoding of subjective values of choice options in a network of brain regions, including but not restricted to medial prefrontal cortex. Our findings demonstrate the general susceptibility of the human decision making system to apparently incidental contextual information. We conclude that the brain incorporates seemingly unrelated value information that modifies decision making outside the decision-maker's awareness.

Led into Temptation? Rewarding Brand Logos Bias the Neural Encoding of Incidental Economic Decisions

PubMed Central

Murawski, Carsten; Harris, Philip G.; Bode, Stefan; Domínguez D., Juan F.; Egan, Gary F.

2012-01-01

Human decision-making is driven by subjective values assigned to alternative choice options. These valuations are based on reward cues. It is unknown, however, whether complex reward cues, such as brand logos, may bias the neural encoding of subjective value in unrelated decisions. In this functional magnetic resonance imaging (fMRI) study, we subliminally presented brand logos preceding intertemporal choices. We demonstrated that priming biased participants' preferences towards more immediate rewards in the subsequent temporal discounting task. This was associated with modulations of the neural encoding of subjective values of choice options in a network of brain regions, including but not restricted to medial prefrontal cortex. Our findings demonstrate the general susceptibility of the human decision making system to apparently incidental contextual information. We conclude that the brain incorporates seemingly unrelated value information that modifies decision making outside the decision-maker's awareness. PMID:22479547

Psychological Connectedness and Intertemporal Choice

ERIC Educational Resources Information Center

Bartels, Daniel M.; Rips, Lance J.

2010-01-01

People tend to attach less value to a good if they know a delay will occur before they obtain it. For example, people value receiving $100 dollars tomorrow more than receiving $100 in 10 years. We explore one reason for this tendency (due to Derek Parfit, 1984): In terms of psychological properties, such as beliefs, values, and goals, the decision…

Decision Makers Calibrate Behavioral Persistence on the Basis of Time-Interval Experience

ERIC Educational Resources Information Center

McGuire, Joseph T.; Kable, Joseph W.

2012-01-01

A central question in intertemporal decision making is why people reverse their own past choices. Someone who initially prefers a long-run outcome might fail to maintain that preference for long enough to see the outcome realized. Such behavior is usually understood as reflecting preference instability or self-control failure. However, if a…

Incomplete water securitization in coupled hydro-human production sytems

NASA Astrophysics Data System (ADS)

van den Boom, B.; Pande, S.

2012-04-01

Due to the dynamics, the externalities and the contingencies involved in managing local water resource for production, the water allocation at basin-level is a subtle balance between laws of nature (gravity; flux) and laws of economics (price; productivity). We study this balance by looking at inter-temporal basin-level water resource allocations in which subbasins enjoy a certain degree of autonomy. Each subbasin is represented as an economic agent i, following a gravity ordering with i=1 representing the most upstream area and i=I the downstream boundary. The water allocation is modeled as a decentralized equilibrium in a coupled conceptual hydro-human production system. Agents i=1,2,...,I in the basin produce a composite good according to a technology that requires water as a main input and that is specific to the subbasin. Agent i manages her use Xi and her storage Si, conceptualizing surface and subsurface water, of water with the purpose of maximizing the utility derived from consumption Ci of the composite good, where Ci is a scalar and Xi and Si are vectors which are composed of one element for each time period and for each contingency. A natural way to consume the good would be to absorb the own production. Yet, the agent may have two more option, namely, she might get a social transfer from other agents or she could use an income from trading water securities with her contiguous neighbors. To study these options, we compare water allocations (Ci, Xi, Si) all i=1,2,...,I for three different settings. We look at allocations without water securitization (water autarky equilibrium EA) first. Next, we describe the imaginary case of full securitization (contingent water markets equilibrium ECM) and, in between, we study limited securitization (incomplete water security equilibrium EWS). We show that allocations under contingent water markets ECM are efficient in the sense that, for the prevailing production technologies, no other allocation exists that is at least good as for all the agents and that makes at least one agent better off . On the other hand, allocations under autarky EA will tend to be inefficient, meaning that other allocations may exist that would be preferred by some agents without compromising the interest of the others. By the same token, the in-between case with water securities will generally also fail to achieve full efficiency. Nonetheless, some securitization will always be at least as good as none while it will be better under conditions of water scarcity that are common in dryland area river basins. Hence water allocations under EWS will generally lead to an improvement over those under EA. It should be noted that the fully efficient equilibrium is only imaginary because it requires a separate water security for every agent, for every period and for every contingency that nature might hold. Clearly, because of dimensionality, this amount of securities will be beyond reach. Therefore, water securitization with a limited number of securities remains as the only practical option to deal with the inefficiency of water allocations under autarky. The economic theory of incomplete markets provides a useful framework to study limited water securitization. We apply the theory in the context of our water allocation framework using an institutional setting where downstream agent i may secure water from upstream agent (i-1) through an agreement that pays for (i-1)'s water savings. In this manner we identify (I-1) water securities, one for each pair of contiguous agents. Each security addresses, at the local level, the interaction of flows over time and over contingencies that might occur. Under scarcity conditions prevalent in many river basins, agents will show an interest to supply and demand such securities. In particular, downstream area can often make more productive use of water. Accordingly, in the water autarky equilibrium EA, they would be willing to pay for more water, while, at the same time, upstream users would be prepared to make water savings to the extent that the payment for the security will exceed the value of foregone production losses. Thus, although inevitably incomplete, water securitization could play a significant role in increasing the efficiency of the allocation of water resources at the basin-level. Evidence from river basins in various parts of the world suggests that gains could be sizeable. This paper dwells upon the advantages and challenges of a transdisciplinary approach that blends the laws of nature with those of economics. It aims to identify efficiency gains from water securitization while addressing the institutional difficulties of implementation due to inherent incompleteness in markets that allow trade in such securities.

Flux Jacobian matrices and generaled Roe average for an equilibrium real gas

NASA Technical Reports Server (NTRS)

Vinokur, Marcel

1988-01-01

Inviscid flux Jacobian matrices and their properties used in numerical solutions of conservation laws are extended to general, equilibrium gas laws. Exact and approximate generalizations of the Roe average are presented. Results are given for one-dimensional flow, and then extended to three-dimensional flow with time-varying grids.

Can Victoria's Secret Change the Future? A Subjective Time Perception Account of Sexual-Cue Effects on Impatience

ERIC Educational Resources Information Center

Kim, B. Kyu; Zauberman, Gal

2013-01-01

Sexual cues influence decisions not only about sex, but also about unrelated outcomes such as money. In the presence of sexual cues, individuals are more "impatient" when making intertemporal monetary tradeoffs, choosing smaller immediate amounts over larger delayed amounts. Previous research has emphasized the power of sexual cues to induce a…

Median Growth Percentiles (MGPs): Assessment of Intertemporal Stability and Correlations with Observational Scores

ERIC Educational Resources Information Center

Pivovarova, Margarita; Amrein-Beardsley, Audrey

2018-01-01

While states are no longer required to set up teacher evaluation systems based in significant part on student test scores, quite a few continue to use value-added (VAMs) or student growth percentile (SGP) models for that purpose. In this study, we analyzed three years of teacher data to illustrate the performance of teachers' median growth…

Cultural Influences on Intertemporal Reasoning

DTIC Science & Technology

2011-11-30

Wiley & Sons. Access at: http://ssrn.com/abstract=1750266. ABSTRACT Elements of economic theory are examined to understand the Euro-American cultural... theory might be understood or misunderstood in other cultures, with the goal of facilitating inter-cultural dialog. The framework is constructed...past, and the tendency of Arab culture to integrate events into an associative gestalt as a basis for understanding and explanation. The results

The Effects of Progressive Taxation on Labor Supply when Hours and Wages Are Jointly Determined

ERIC Educational Resources Information Center

Aaronson, Daniel; French, Eric

2009-01-01

This paper extends a standard intertemporal labor supply model to account for progressive taxation as well as the joint determination of hourly wages and hours worked. We show that these two factors can have implications for both estimating labor supply elasticities as well as for using these elasticities in tax analysis. Failure to account for…

Time discounting and time preference in animals: A critical review.

PubMed

Hayden, Benjamin Y

2016-02-01

Animals are an important model for studies of impulsivity and self-control. Many studies have made use of the intertemporal choice task, which pits small rewards available sooner against larger rewards available later (typically several seconds), repeated over many trials. Preference for the sooner reward is often taken to indicate impulsivity and/or a failure of self-control. This review shows that very little evidence supports this assumption; on the contrary, ostensible discounting behavior may reflect a boundedly rational but not necessarily impulsive reward-maximizing strategy. Specifically, animals may discount weakly, or even adopt a long-term rate-maximizing strategy, but fail to fully incorporate postreward delays into their choices. This failure may reflect learning biases. Consequently, tasks that measure animal discounting may greatly overestimate the true discounting and may be confounded by processes unrelated to time preferences. If so, animals may be much more patient than is widely believed; human and animal intertemporal choices may reflect unrelated mental operations; and the shared hyperbolic shape of the human and animal discount curves, which is used to justify cross-species comparisons, may be coincidental. The discussion concludes with a consideration of alternative ways to measure self-control in animals.

Errors Affect Hypothetical Intertemporal Food Choice in Women

PubMed Central

Sellitto, Manuela; di Pellegrino, Giuseppe

2014-01-01

Growing evidence suggests that the ability to control behavior is enhanced in contexts in which errors are more frequent. Here we investigated whether pairing desirable food with errors could decrease impulsive choice during hypothetical temporal decisions about food. To this end, healthy women performed a Stop-signal task in which one food cue predicted high-error rate, and another food cue predicted low-error rate. Afterwards, we measured participants’ intertemporal preferences during decisions between smaller-immediate and larger-delayed amounts of food. We expected reduced sensitivity to smaller-immediate amounts of food associated with high-error rate. Moreover, taking into account that deprivational states affect sensitivity for food, we controlled for participants’ hunger. Results showed that pairing food with high-error likelihood decreased temporal discounting. This effect was modulated by hunger, indicating that, the lower the hunger level, the more participants showed reduced impulsive preference for the food previously associated with a high number of errors as compared with the other food. These findings reveal that errors, which are motivationally salient events that recruit cognitive control and drive avoidance learning against error-prone behavior, are effective in reducing impulsive choice for edible outcomes. PMID:25244534

Subjective costs drive overly patient foraging strategies in rats on an intertemporal foraging task.

PubMed

Wikenheiser, Andrew M; Stephens, David W; Redish, A David

2013-05-14

Laboratory studies of decision making often take the form of two-alternative, forced-choice paradigms. In natural settings, however, many decision problems arise as stay/go choices. We designed a foraging task to test intertemporal decision making in rats via stay/go decisions. Subjects did not follow the rate-maximizing strategy of choosing only food items associated with short delays. Instead, rats were often willing to wait for surprisingly long periods, and consequently earned a lower rate of food intake than they might have by ignoring long-delay options. We tested whether foraging theory or delay discounting models predicted the behavior we observed but found that these models could not account for the strategies subjects selected. Subjects' behavior was well accounted for by a model that incorporated a cost for rejecting potential food items. Interestingly, subjects' cost sensitivity was proportional to environmental richness. These findings are at odds with traditional normative accounts of decision making but are consistent with retrospective considerations having a deleterious influence on decisions (as in the "sunk-cost" effect). More broadly, these findings highlight the utility of complementing existing assays of decision making with tasks that mimic more natural decision topologies.

No evidence for common processes of cognitive control and self-control.

PubMed

Scherbaum, Stefan; Frisch, Simon; Holfert, Anna-Maria; O'Hora, Denis; Dshemuchadse, Maja

2018-01-01

Cognitive control and self-control are often used as interchangeable terms. Both terms refer to the ability to pursue long-term goals, but the types of controlled behavior that are typically associated with these terms differ, at least superficially. Cognitive control is observed in the control of attention and the overcoming of habitual responses, while self-control is observed in resistance to short-term impulses and temptations. Evidence from clinical studies and neuroimaging studies suggests that below these superficial differences, common control process (e.g., inhibition) might guide both types of controlled behavior. Here, we study this hypothesis in a behavioral experiment, which interlaced trials of a Simon task with trials of an intertemporal decision task. If cognitive control and self-control depend on a common control process, we expected conflict adaptation from Simon task trials to lead to increased self-control in the intertemporal decision trials. However, despite successful manipulations of conflict and conflict adaptation, we found no evidence for this hypothesis. We investigate a number of alternative explanations of this result and conclude that the differences between cognitive control and self-control are not superficial, but rather reflect differences at the process level. Copyright © 2017 Elsevier B.V. All rights reserved.

Subjective costs drive overly patient foraging strategies in rats on an intertemporal foraging task

PubMed Central

Wikenheiser, Andrew M.; Stephens, David W.; Redish, A. David

2013-01-01

Laboratory studies of decision making often take the form of two-alternative, forced-choice paradigms. In natural settings, however, many decision problems arise as stay/go choices. We designed a foraging task to test intertemporal decision making in rats via stay/go decisions. Subjects did not follow the rate-maximizing strategy of choosing only food items associated with short delays. Instead, rats were often willing to wait for surprisingly long periods, and consequently earned a lower rate of food intake than they might have by ignoring long-delay options. We tested whether foraging theory or delay discounting models predicted the behavior we observed but found that these models could not account for the strategies subjects selected. Subjects’ behavior was well accounted for by a model that incorporated a cost for rejecting potential food items. Interestingly, subjects’ cost sensitivity was proportional to environmental richness. These findings are at odds with traditional normative accounts of decision making but are consistent with retrospective considerations having a deleterious influence on decisions (as in the “sunk-cost” effect). More broadly, these findings highlight the utility of complementing existing assays of decision making with tasks that mimic more natural decision topologies. PMID:23630289

Anomaly on Superspace of Time Series Data

NASA Astrophysics Data System (ADS)

Capozziello, Salvatore; Pincak, Richard; Kanjamapornkul, Kabin

2017-11-01

We apply the G-theory and anomaly of ghost and antighost fields in the theory of supersymmetry to study a superspace over time series data for the detection of hidden general supply and demand equilibrium in the financial market. We provide proof of the existence of a general equilibrium point over 14 extradimensions of the new G-theory compared with the M-theory of the 11 dimensions model of Edward Witten. We found that the process of coupling between nonequilibrium and equilibrium spinor fields of expectation ghost fields in the superspace of time series data induces an infinitely long exact sequence of cohomology from a short exact sequence of moduli state space model. If we assume that the financial market is separated into two topological spaces of supply and demand as the D-brane and anti-D-brane model, then we can use a cohomology group to compute the stability of the market as a stable point of the general equilibrium of the interaction between D-branes of the market. We obtain the result that the general equilibrium will exist if and only if the 14th Batalin-Vilkovisky cohomology group with the negative dimensions underlying 14 major hidden factors influencing the market is zero.

General Equilibrium Models: Improving the Microeconomics Classroom

ERIC Educational Resources Information Center

Nicholson, Walter; Westhoff, Frank

2009-01-01

General equilibrium models now play important roles in many fields of economics including tax policy, environmental regulation, international trade, and economic development. The intermediate microeconomics classroom has not kept pace with these trends, however. Microeconomics textbooks primarily focus on the insights that can be drawn from the…

Optimal Electricity Charge Strategy Based on Price Elasticity of Demand for Users

NASA Astrophysics Data System (ADS)

Li, Xin; Xu, Daidai; Zang, Chuanzhi

The price elasticity is very important for the prediction of electricity demand. This paper mainly establishes the price elasticity coefficient for electricity in single period and inter-temporal. Then, a charging strategy is established based on these coefficients. To evaluate the strategy proposed, simulations of the two elastic coefficients are carried out based on the history data of a certain region.

A Cross-Sectional Model of Annual Interregional Migration and Employment Growth: Intertemporal Evidence of Structural Change, 1958-1975.

DTIC Science & Technology

1981-04-01

results using these same five amenities, and we have therefore followed his innovative work. The variables are annual heating degree days (liDi...Ototmeket. Bradford, "Exopectd Deand to, the PP 296 Trott Robert Ps end Valel Roert C Th. U.S. Navy to Setve Of An, Inrtrumeott of u.s Conit,b Biraidliod and

Is Tomorrow Another Day? The Labor Supply of New York City Cabdrivers.

ERIC Educational Resources Information Center

Farber, Henry S.

2005-01-01

The labor supply of taxi drivers is consistent with the existence of intertemporal substitution. My analysis of the stopping behavior of New York City cabdrivers shows that daily income effects are small and that the decision to stop work at a particular point on a given day is primarily related to cumulative daily hours to that point. This is in…

Isolating Behavioral Mechanisms of Inter-Temporal Choice: Nicotine Effects on Delay Discounting and Amount Sensitivity

ERIC Educational Resources Information Center

Locey, Matthew L.; Dallery, Jesse

2009-01-01

Many drugs of abuse produce changes in impulsive choice, that is, choice for a smaller-sooner reinforcer over a larger-later reinforcer. Because the alternatives differ in both delay and amount, it is not clear whether these drug effects are due to the differences in reinforcer delay or amount. To isolate the effects of delay, we used a titrating…

An Exploration of Dual Systems via Time Pressure Manipulation in Decision-making Problems

NASA Astrophysics Data System (ADS)

Guo, Lisa

Every day, decisions need to be made where time is a limiting factor. Regardless of situation, time constraints often place a premium on rapid decision-making. Researchers have been interested in studying this human behavior and understanding its underlying cognitive processes. In previous studies, scientists have believed that the cognitive processes underlying decision-making behavior were consistent with dual-process modes of thinking. Critics of dual-process theory question the vagueness of its definition, and claim that single-process accounts can explain the data just as well. My aim is to elucidate the cognitive processes that underlie decisions which involve some level of risk through the experimental manipulation of time pressure. Using this method, I hope to distinguish between competing hypotheses related to the origin of the effect. I will explore three types of decisions that illustrate these concepts: risky decision-making involving gambles, intertemporal choice, and one-shot public goods games involving social cooperation. In our experiments, participants made decisions about gambles framed as either gains or losses; decided upon intertemporal choices for smaller but sooner rewards or larger but later rewards; and played a one-shot public goods game involving social cooperation and contributing an amount of money to a group. In each case, we experimentally manipulated time pressure, either within subjects or among individuals. Results showed under time pressure, increased framing effects under in both hypothetical and incentivized choices; and greater contributions and cooperation among individuals, lending support to the dual process hypothesis that these effects arise from a fast, intuitive system. However, our intertemporal choice experiment showed that time constraints led to increased selection of the larger but later options, which suggests that the magnitude of the reward may play larger role in choice selection under cognitive load than previously studied. This diverges from the current dual-process interpretation that myopic choices under time pressure favor smaller but sooner rewards, and suggests that more studies are needed in this realm to disentangle the intuitive from the deliberative system through the manipulation of cognitive load.

Potential and flux field landscape theory. I. Global stability and dynamics of spatially dependent non-equilibrium systems.

PubMed

Wu, Wei; Wang, Jin

2013-09-28

We established a potential and flux field landscape theory to quantify the global stability and dynamics of general spatially dependent non-equilibrium deterministic and stochastic systems. We extended our potential and flux landscape theory for spatially independent non-equilibrium stochastic systems described by Fokker-Planck equations to spatially dependent stochastic systems governed by general functional Fokker-Planck equations as well as functional Kramers-Moyal equations derived from master equations. Our general theory is applied to reaction-diffusion systems. For equilibrium spatially dependent systems with detailed balance, the potential field landscape alone, defined in terms of the steady state probability distribution functional, determines the global stability and dynamics of the system. The global stability of the system is closely related to the topography of the potential field landscape in terms of the basins of attraction and barrier heights in the field configuration state space. The effective driving force of the system is generated by the functional gradient of the potential field alone. For non-equilibrium spatially dependent systems, the curl probability flux field is indispensable in breaking detailed balance and creating non-equilibrium condition for the system. A complete characterization of the non-equilibrium dynamics of the spatially dependent system requires both the potential field and the curl probability flux field. While the non-equilibrium potential field landscape attracts the system down along the functional gradient similar to an electron moving in an electric field, the non-equilibrium flux field drives the system in a curly way similar to an electron moving in a magnetic field. In the small fluctuation limit, the intrinsic potential field as the small fluctuation limit of the potential field for spatially dependent non-equilibrium systems, which is closely related to the steady state probability distribution functional, is found to be a Lyapunov functional of the deterministic spatially dependent system. Therefore, the intrinsic potential landscape can characterize the global stability of the deterministic system. The relative entropy functional of the stochastic spatially dependent non-equilibrium system is found to be the Lyapunov functional of the stochastic dynamics of the system. Therefore, the relative entropy functional quantifies the global stability of the stochastic system with finite fluctuations. Our theory offers an alternative general approach to other field-theoretic techniques, to study the global stability and dynamics of spatially dependent non-equilibrium field systems. It can be applied to many physical, chemical, and biological spatially dependent non-equilibrium systems.

Weak Acid Ionization Constants and the Determination of Weak Acid-Weak Base Reaction Equilibrium Constants in the General Chemistry Laboratory

ERIC Educational Resources Information Center

Nyasulu, Frazier; McMills, Lauren; Barlag, Rebecca

2013-01-01

A laboratory to determine the equilibrium constants of weak acid negative weak base reactions is described. The equilibrium constants of component reactions when multiplied together equal the numerical value of the equilibrium constant of the summative reaction. The component reactions are weak acid ionization reactions, weak base hydrolysis…

Is the Reaction Equilibrium Composition in Non-ideal Mixtures Uniquely Determined by the Initial Composition?

NASA Astrophysics Data System (ADS)

Sefcik, Jan

1998-05-01

Reaction equilibrium can be mathematically described by the equilibrium equation and the reaction equilibrium composition can be calculated by solving this equation. It can be proved by non-elementary thermodynamic arguments that for a generic system with given initial composition, temperature and pressure there is a unique stable equilibrium state corresponding to the global minimum of the Gibbs free energy function. However, when the concept of equilibrium is introduced in undergraduate chemistry and chemical engineering courses, such arguments are generally not accessible. When there is a single reaction equilibrium among mixture components and the components form an ideal mixture, it has been demonstrated by a simple, elegant mathematical argument that there is a unique composition satisfying the equilibrium equation. It has been also suggested that this particular argument extends to non-ideal mixtures by simply incorporating activity coefficients. We show that the argument extension to non-ideal systems is not generally valid. Increasing non-ideality can result in non-monotonicity of the function crucial for the simple uniqueness argument, and only later it leads to non-uniqueness and hence phase separation. The main feature responsible for this is a composition dependence of activity coefficients in non-ideal mixtures.

Degree of coupling and efficiency of energy converters far-from-equilibrium

NASA Astrophysics Data System (ADS)

Vroylandt, Hadrien; Lacoste, David; Verley, Gatien

2018-02-01

In this paper, we introduce a real symmetric and positive semi-definite matrix, which we call the non-equilibrium conductance matrix, and which generalizes the Onsager response matrix for a system in a non-equilibrium stationary state. We then express the thermodynamic efficiency in terms of the coefficients of this matrix using a parametrization similar to the one used near equilibrium. This framework, then valid arbitrarily far from equilibrium allows to set bounds on the thermodynamic efficiency by a universal function depending only on the degree of coupling between input and output currents. It also leads to new general power-efficiency trade-offs valid for macroscopic machines that are compared to trade-offs previously obtained from uncertainty relations. We illustrate our results on an unicycle heat to heat converter and on a discrete model of a molecular motor.

Computer Assisted Instruction in Economics: An Approach for Illustrating General Equilibrium Concepts.

ERIC Educational Resources Information Center

Gillespie, Robert W.

A market exchange simulation utilizing the PLATO computer-assisted instructional system at the University of Illinois has been designed to teach students the principles of a general equilibrium system. It serves a laboratory function which supplements traditional instruction by stimulating students' interests and providing them with illustrations…

A general equilibrium model of a production economy with asset markets

NASA Astrophysics Data System (ADS)

Raberto, Marco; Teglio, Andrea; Cincotti, Silvano

2006-10-01

In this paper, a general equilibrium model of a monetary production economy is presented. The model is characterized by three classes of agents: a representative firm, heterogeneous households, and the government. Two markets (i.e., a labour market and a goods market, are considered) and two assets are traded in exchange of money, namely, government bonds and equities. Households provide the labour force and decide on consumption and savings, whereas the firm provides consumption goods and demands labour. The government receives taxes from households and pays interests on debt. The Walrasian equilibrium is derived analytically. The dynamics through quantity constrained equilibria out from the Walrasian equilibrium is also studied by means of computer simulations.

Siphon flows in isolated magnetic flux tubes. III - The equilibrium path of the flux-tube arch

NASA Technical Reports Server (NTRS)

Thomas, John H.; Montesinos, Benjamin

1990-01-01

It is shown how to calculate the equilibrium path of a thin magnetic flux tube in a stratified, nonmagnetic atmosphere when the flux tube contains a steady siphon flow. The equilbrium path of a static thin flux tube in an infinite stratified atmosphere generally takes the form of a symmetric arch of finite width, with the flux tube becoming vertical at either end of the arch. A siphon flow within the flux tube increases the curvature of the arched equilibrium path in order that the net magnetic tension force can balance the inertial force of the flow, which tries to straighten the flux tube. Thus, a siphon flow reduces the width of the arched equilibrium path, with faster flows producing narrower arches. The effect of the siphon flow on the equilibrium path is generally greater for flux tubes of weaker magnetic field strength. Examples of the equilibrium are shown for both isothemal and adiabatic siphon flows in thin flux tubes in an isothermal external atmosphere.

Radiative heat transfer and nonequilibrium Casimir-Lifshitz force in many-body systems with planar geometry

NASA Astrophysics Data System (ADS)

Latella, Ivan; Ben-Abdallah, Philippe; Biehs, Svend-Age; Antezza, Mauro; Messina, Riccardo

2017-05-01

A general theory of photon-mediated energy and momentum transfer in N -body planar systems out of thermal equilibrium is introduced. It is based on the combination of the scattering theory and the fluctuational-electrodynamics approach in many-body systems. By making a Landauer-like formulation of the heat transfer problem, explicit formulas for the energy transmission coefficients between two distinct slabs as well as the self-coupling coefficients are derived and expressed in terms of the reflection and transmission coefficients of the single bodies. We also show how to calculate local equilibrium temperatures in such systems. An analogous formulation is introduced to quantify momentum transfer coefficients describing Casimir-Lifshitz forces out of thermal equilibrium. Forces at thermal equilibrium are readily obtained as a particular case. As an illustration of this general theoretical framework, we show on three-body systems how the presence of a fourth slab can impact equilibrium temperatures in heat-transfer problems and equilibrium positions resulting from the forces acting on the system.

Functional thermo-dynamics: a generalization of dynamic density functional theory to non-isothermal situations.

PubMed

Anero, Jesús G; Español, Pep; Tarazona, Pedro

2013-07-21

We present a generalization of Density Functional Theory (DFT) to non-equilibrium non-isothermal situations. By using the original approach set forth by Gibbs in his consideration of Macroscopic Thermodynamics (MT), we consider a Functional Thermo-Dynamics (FTD) description based on the density field and the energy density field. A crucial ingredient of the theory is an entropy functional, which is a concave functional. Therefore, there is a one to one connection between the density and energy fields with the conjugate thermodynamic fields. The connection between the three levels of description (MT, DFT, FTD) is clarified through a bridge theorem that relates the entropy of different levels of description and that constitutes a generalization of Mermin's theorem to arbitrary levels of description whose relevant variables are connected linearly. Although the FTD level of description does not provide any new information about averages and correlations at equilibrium, it is a crucial ingredient for the dynamics in non-equilibrium states. We obtain with the technique of projection operators the set of dynamic equations that describe the evolution of the density and energy density fields from an initial non-equilibrium state towards equilibrium. These equations generalize time dependent density functional theory to non-isothermal situations. We also present an explicit model for the entropy functional for hard spheres.

Delay Discounting: Pigeon, Rat, Human – Does it Matter?

PubMed Central

Vanderveldt, Ariana; Oliveira, Luís; Green, Leonard

2016-01-01

Delay discounting refers to the decrease in subjective value of an outcome as the time to its receipt increases. Across species and situations, animals discount delayed rewards, and their discounting is well-described by a hyperboloid function. The current review begins with a comparison of discounting models and the procedures used to assess delay discounting in nonhuman animals. We next discuss the generality of discounting, reviewing the effects of different variables on the degree of discounting delayed reinforcers by nonhuman animals. Despite the many similarities in discounting observed between human and nonhuman animals, several differences have been proposed (e.g., the magnitude effect; nonhuman animals discount over a matter of seconds whereas humans report willing to wait months, if not years before receiving a reward), raising the possibility of fundamental species differences in intertemporal choice. After evaluating these differences, we discuss delay discounting from an adaptationist perspective. The pervasiveness of discounting across species and situations suggests it is a fundamental process underlying decision making. PMID:26881899

Deadline rush: a time management phenomenon and its mathematical description.

PubMed

König, Cornelius J; Kleinmann, Martin

2005-01-01

A typical time management phenomenon is the rush before a deadline. Behavioral decision making research can be used to predict how behavior changes before a deadline. People are likely not to work on a project with a deadline in the far future because they generally discount future outcomes. Only when the deadline is close are people likely to work. On the basis of recent intertemporal choice experiments, the authors argue that a hyperbolic function should provide a more accurate description of the deadline rush than an exponential function predicted by an economic model of discounted utility. To show this, the fit of the hyperbolic and the exponential function were compared with data sets that describe when students study for exams. As predicted, the hyperbolic function fit the data significantly better than the exponential function. The implication for time management decisions is that they are most likely to be inconsistent over time (i.e., people make a plan how to use their time but do not follow it).

Fluctuation-dissipation relation and stationary distribution of an exactly solvable many-particle model for active biomatter far from equilibrium.

PubMed

Netz, Roland R

2018-05-14

An exactly solvable, Hamiltonian-based model of many massive particles that are coupled by harmonic potentials and driven by stochastic non-equilibrium forces is introduced. The stationary distribution and the fluctuation-dissipation relation are derived in closed form for the general non-equilibrium case. Deviations from equilibrium are on one hand characterized by the difference of the obtained stationary distribution from the Boltzmann distribution; this is possible because the model derives from a particle Hamiltonian. On the other hand, the difference between the obtained non-equilibrium fluctuation-dissipation relation and the standard equilibrium fluctuation-dissipation theorem allows us to quantify non-equilibrium in an alternative fashion. Both indicators of non-equilibrium behavior, i.e., deviations from the Boltzmann distribution and deviations from the equilibrium fluctuation-dissipation theorem, can be expressed in terms of a single non-equilibrium parameter α that involves the ratio of friction coefficients and random force strengths. The concept of a non-equilibrium effective temperature, which can be defined by the relation between fluctuations and the dissipation, is by comparison with the exactly derived stationary distribution shown not to hold, even if the effective temperature is made frequency dependent. The analysis is not confined to close-to-equilibrium situations but rather is exact and thus holds for arbitrarily large deviations from equilibrium. Also, the suggested harmonic model can be obtained from non-linear mechanical network systems by an expansion in terms of suitably chosen deviatory coordinates; the obtained results should thus be quite general. This is demonstrated by comparison of the derived non-equilibrium fluctuation dissipation relation with experimental data on actin networks that are driven out of equilibrium by energy-consuming protein motors. The comparison is excellent and allows us to extract the non-equilibrium parameter α from experimental spectral response and fluctuation data.

Fluctuation-dissipation relation and stationary distribution of an exactly solvable many-particle model for active biomatter far from equilibrium

NASA Astrophysics Data System (ADS)

Netz, Roland R.

2018-05-01

An exactly solvable, Hamiltonian-based model of many massive particles that are coupled by harmonic potentials and driven by stochastic non-equilibrium forces is introduced. The stationary distribution and the fluctuation-dissipation relation are derived in closed form for the general non-equilibrium case. Deviations from equilibrium are on one hand characterized by the difference of the obtained stationary distribution from the Boltzmann distribution; this is possible because the model derives from a particle Hamiltonian. On the other hand, the difference between the obtained non-equilibrium fluctuation-dissipation relation and the standard equilibrium fluctuation-dissipation theorem allows us to quantify non-equilibrium in an alternative fashion. Both indicators of non-equilibrium behavior, i.e., deviations from the Boltzmann distribution and deviations from the equilibrium fluctuation-dissipation theorem, can be expressed in terms of a single non-equilibrium parameter α that involves the ratio of friction coefficients and random force strengths. The concept of a non-equilibrium effective temperature, which can be defined by the relation between fluctuations and the dissipation, is by comparison with the exactly derived stationary distribution shown not to hold, even if the effective temperature is made frequency dependent. The analysis is not confined to close-to-equilibrium situations but rather is exact and thus holds for arbitrarily large deviations from equilibrium. Also, the suggested harmonic model can be obtained from non-linear mechanical network systems by an expansion in terms of suitably chosen deviatory coordinates; the obtained results should thus be quite general. This is demonstrated by comparison of the derived non-equilibrium fluctuation dissipation relation with experimental data on actin networks that are driven out of equilibrium by energy-consuming protein motors. The comparison is excellent and allows us to extract the non-equilibrium parameter α from experimental spectral response and fluctuation data.

Assessing effects of mitigation strategies for global climate change with an intertemporal model of the U.S. forest and agriculture sectors.

Treesearch

Ralph J. Alig; Darius M. Adams; Bruce McCarl; J.M. Callaway; Steven Winnett

1997-01-01

A model of product and land markets in U.S. forest and agricultural sectors is used to examine the private forest management, land use, and market implications of carbon sequestration policies implemented in a "least social cost" fashion. Results suggest: policy-induced land use changes may generate compensating land use shifts through markets: land use...

Arab Cultural Influences on Intertemporal Reasoning

DTIC Science & Technology

2011-11-30

Retrieval is facilitated when retrieval cues have a high similarity to the encoded information. As yet, we have little research on Arab culture...activation theory of memory. Journal of Verbal Learing and Verbal Behavior , 22, 261-295. Bartlett, F. C. (1932). Remembering: A study in experimental...in how day-to-day experience is both encoded and recalled as part of reconstructing recent personal histories (e.g., where one has been) in terms of

Cultural Influences on Intertemporal Reasoning: An Annotated Bibliography

DTIC Science & Technology

2011-11-30

International Conference on Cross- Cultural Decision Making, Miami, FL.5 MacGregor, D. G., & Godfrey, J. (2011, February). Observations on the Concept of Risk...encounter with an Arab culture , or to be better prepared after their first encounter. The focus is a great deal of basic cultural concepts ...workers, visitors and telephone). (Note: The concept of polychronic and monochromic cultures was originally advanced by Edward Hall in his book, The

The hunt for the perfect discounting function and a reckoning of time perception.

PubMed

Namboodiri, Vijay Mk; Hussain Shuler, Marshall G

2016-10-01

Making decisions that factor the cost of time is fundamental to survival. Yet, while it is readily appreciated that our perception of time is intimately involved in this process, theories regarding intertemporal decision-making and theories regarding time perception are treated, largely, independently. Even within these respective domains, models providing good fits to data fail to provide insight as to why, from a normative sense, those fits should take their apparent form. Conversely, normative models that proffer a rationalization for why an agent should weigh options in a particular way, or to perceive time in a particular way, fail to account for the full body of well-established experimental evidence. Here we review select, yet key advances in our understanding, identifying conceptual breakthroughs in the fields of intertemporal decision-making and in time perception, as well as their limits and failings in the face of hard-won experimental observation. On this background of accrued knowledge, a new conception unifying the domains of decision-making and time perception is put forward (Training-Integrated Maximization of Reinforcement Rate, TIMERR) to provide a better fit to observations and a more parsimonious reckoning of why we make choices, and thereby perceive time, the way we do. Copyright © 2016 Elsevier Ltd. All rights reserved.

The procrastinators want it now: Behavioral and event-related potential evidence of the procrastination of intertemporal choices.

PubMed

Wu, Haiyan; Gui, Danyang; Lin, Wenzheng; Gu, Ruolei; Zhu, Xiangru; Liu, Xun

2016-08-01

Much past research has focused on the correlation between procrastination and personality traits (e.g., impulsivity). According to the temporal motivation theory, procrastinators are impulsive and sensitive to delays in time. However, there is still a lack of direct evidence of the tendency of procrastinators to prefer immediate over future rewards. To investigate this question, we recorded event-related potentials (ERPs) in the brain while participants performed an intertemporal choice task involving both time delay and reward processing. The participants were assigned to a high procrastination group and a low procrastination group according to their scores on self-report measures. We found that high procrastination participants preferred immediate rewards compared to future ones whereas low procrastination participants did not. High procrastinators also exhibited a larger and delayed P2 component, indicating delay time processing and abnormal reward processing. No significant effect associated with procrastination was found on the P300 component. Taken together, these findings suggest that high procrastinators are more impulsive and encode the information of delay time more slowly but with a higher level of motivation-driven attention. The current study substantiates higher impulsivity in procrastination and verifies that a difference exists in the sensitivity to time delay between high and low procrastinators. Copyright © 2016 Elsevier Inc. All rights reserved.

Equilibrium theory of island biogeography: A review

Treesearch

Angela D. Yu; Simon A. Lei

2001-01-01

The topography, climatic pattern, location, and origin of islands generate unique patterns of species distribution. The equilibrium theory of island biogeography creates a general framework in which the study of taxon distribution and broad island trends may be conducted. Critical components of the equilibrium theory include the species-area relationship, island-...

Bifurcation and Stability Analysis of the Equilibrium States in Thermodynamic Systems in a Small Vicinity of the Equilibrium Values of Parameters

NASA Astrophysics Data System (ADS)

Barsuk, Alexandr A.; Paladi, Florentin

2018-04-01

The dynamic behavior of thermodynamic system, described by one order parameter and one control parameter, in a small neighborhood of ordinary and bifurcation equilibrium values of the system parameters is studied. Using the general methods of investigating the branching (bifurcations) of solutions for nonlinear equations, we performed an exhaustive analysis of the order parameter dependences on the control parameter in a small vicinity of the equilibrium values of parameters, including the stability analysis of the equilibrium states, and the asymptotic behavior of the order parameter dependences on the control parameter (bifurcation diagrams). The peculiarities of the transition to an unstable state of the system are discussed, and the estimates of the transition time to the unstable state in the neighborhood of ordinary and bifurcation equilibrium values of parameters are given. The influence of an external field on the dynamic behavior of thermodynamic system is analyzed, and the peculiarities of the system dynamic behavior are discussed near the ordinary and bifurcation equilibrium values of parameters in the presence of external field. The dynamic process of magnetization of a ferromagnet is discussed by using the general methods of bifurcation and stability analysis presented in the paper.

Conformal field theory out of equilibrium: a review

NASA Astrophysics Data System (ADS)

Bernard, Denis; Doyon, Benjamin

2016-06-01

We provide a pedagogical review of the main ideas and results in non-equilibrium conformal field theory and connected subjects. These concern the understanding of quantum transport and its statistics at and near critical points. Starting with phenomenological considerations, we explain the general framework, illustrated by the example of the Heisenberg quantum chain. We then introduce the main concepts underlying conformal field theory (CFT), the emergence of critical ballistic transport, and the CFT scattering construction of non-equilibrium steady states. Using this we review the theory for energy transport in homogeneous one-dimensional critical systems, including the complete description of its large deviations and the resulting (extended) fluctuation relations. We generalize some of these ideas to one-dimensional critical charge transport and to the presence of defects, as well as beyond one-dimensional criticality. We describe non-equilibrium transport in free-particle models, where connections are made with generalized Gibbs ensembles, and in higher-dimensional and non-integrable quantum field theories, where the use of the powerful hydrodynamic ideas for non-equilibrium steady states is explained. We finish with a list of open questions. The review does not assume any advanced prior knowledge of conformal field theory, large-deviation theory or hydrodynamics.

Temperature in and out of equilibrium: A review of concepts, tools and attempts

NASA Astrophysics Data System (ADS)

Puglisi, A.; Sarracino, A.; Vulpiani, A.

2017-11-01

We review the general aspects of the concept of temperature in equilibrium and non-equilibrium statistical mechanics. Although temperature is an old and well-established notion, it still presents controversial facets. After a short historical survey of the key role of temperature in thermodynamics and statistical mechanics, we tackle a series of issues which have been recently reconsidered. In particular, we discuss different definitions and their relevance for energy fluctuations. The interest in such a topic has been triggered by the recent observation of negative temperatures in condensed matter experiments. Moreover, the ability to manipulate systems at the micro and nano-scale urges to understand and clarify some aspects related to the statistical properties of small systems (as the issue of temperature's ;fluctuations;). We also discuss the notion of temperature in a dynamical context, within the theory of linear response for Hamiltonian systems at equilibrium and stochastic models with detailed balance, and the generalized fluctuation-response relations, which provide a hint for an extension of the definition of temperature in far-from-equilibrium systems. To conclude we consider non-Hamiltonian systems, such as granular materials, turbulence and active matter, where a general theoretical framework is still lacking.

Using the Logarithmic Concentration Diagram, Log "C", to Teach Acid-Base Equilibrium

ERIC Educational Resources Information Center

Kovac, Jeffrey

2012-01-01

Acid-base equilibrium is one of the most important and most challenging topics in a typical general chemistry course. This article introduces an alternative to the algebraic approach generally used in textbooks, the graphical log "C" method. Log "C" diagrams provide conceptual insight into the behavior of aqueous acid-base systems and allow…

Perspective: Maximum caliber is a general variational principle for dynamical systems

NASA Astrophysics Data System (ADS)

Dixit, Purushottam D.; Wagoner, Jason; Weistuch, Corey; Pressé, Steve; Ghosh, Kingshuk; Dill, Ken A.

2018-01-01

We review here Maximum Caliber (Max Cal), a general variational principle for inferring distributions of paths in dynamical processes and networks. Max Cal is to dynamical trajectories what the principle of maximum entropy is to equilibrium states or stationary populations. In Max Cal, you maximize a path entropy over all possible pathways, subject to dynamical constraints, in order to predict relative path weights. Many well-known relationships of non-equilibrium statistical physics—such as the Green-Kubo fluctuation-dissipation relations, Onsager's reciprocal relations, and Prigogine's minimum entropy production—are limited to near-equilibrium processes. Max Cal is more general. While it can readily derive these results under those limits, Max Cal is also applicable far from equilibrium. We give examples of Max Cal as a method of inference about trajectory distributions from limited data, finding reaction coordinates in bio-molecular simulations, and modeling the complex dynamics of non-thermal systems such as gene regulatory networks or the collective firing of neurons. We also survey its basis in principle and some limitations.

Perspective: Maximum caliber is a general variational principle for dynamical systems.

PubMed

Dixit, Purushottam D; Wagoner, Jason; Weistuch, Corey; Pressé, Steve; Ghosh, Kingshuk; Dill, Ken A

2018-01-07

We review here Maximum Caliber (Max Cal), a general variational principle for inferring distributions of paths in dynamical processes and networks. Max Cal is to dynamical trajectories what the principle of maximum entropy is to equilibrium states or stationary populations. In Max Cal, you maximize a path entropy over all possible pathways, subject to dynamical constraints, in order to predict relative path weights. Many well-known relationships of non-equilibrium statistical physics-such as the Green-Kubo fluctuation-dissipation relations, Onsager's reciprocal relations, and Prigogine's minimum entropy production-are limited to near-equilibrium processes. Max Cal is more general. While it can readily derive these results under those limits, Max Cal is also applicable far from equilibrium. We give examples of Max Cal as a method of inference about trajectory distributions from limited data, finding reaction coordinates in bio-molecular simulations, and modeling the complex dynamics of non-thermal systems such as gene regulatory networks or the collective firing of neurons. We also survey its basis in principle and some limitations.

Students' Understanding of Equilibrium and Stability: The Case of Dynamic Systems

ERIC Educational Resources Information Center

Canu, Michaël; de Hosson, Cécile; Duque, Mauricio

2016-01-01

Engineering students in control courses have been observed to lack an understanding of equilibrium and stability, both of which are crucial concepts in this discipline. The introduction of these concepts is generally based on the study of classical examples from Newtonian mechanics supplemented with a control system. Equilibrium and stability are…

The Equilibrium Constant for Bromothymol Blue: A General Chemistry Laboratory Experiment Using Spectroscopy

ERIC Educational Resources Information Center

Klotz, Elsbeth; Doyle, Robert; Gross, Erin; Mattson, Bruce

2011-01-01

A simple, inexpensive, and environmentally friendly undergraduate laboratory experiment is described in which students use visible spectroscopy to determine a numerical value for an equilibrium constant, K[subscript c]. The experiment correlates well with the lecture topic of equilibrium even though the subject of the study is an acid-base…

Using a Spreadsheet Scroll Bar to Solve Equilibrium Concentrations

ERIC Educational Resources Information Center

Raviolo, Andres

2012-01-01

A simple, conceptual method is described for using the spreadsheet scroll bar to find the composition of a system at chemical equilibrium. Simulation of any kind of chemical equilibrium can be carried out using this method, and the effects of different disturbances can be predicted. This simulation, which can be used in general chemistry…

Distributed Nash Equilibrium Seeking for Generalized Convex Games with Shared Constraints

NASA Astrophysics Data System (ADS)

Sun, Chao; Hu, Guoqiang

2018-05-01

In this paper, we deal with the problem of finding a Nash equilibrium for a generalized convex game. Each player is associated with a convex cost function and multiple shared constraints. Supposing that each player can exchange information with its neighbors via a connected undirected graph, the objective of this paper is to design a Nash equilibrium seeking law such that each agent minimizes its objective function in a distributed way. Consensus and singular perturbation theories are used to prove the stability of the system. A numerical example is given to show the effectiveness of the proposed algorithms.

Equivalence of equations describing trace element distribution during equilibrium partial melting

NASA Technical Reports Server (NTRS)

Consolmagno, G. J.; Drake, M. J.

1976-01-01

It is shown that four equations used for calculating the evolution of trace-element abundances during equilibrium partial melting are mathematically equivalent. The equations include those of Hertogen and Gijbels (1976), Shaw (1970), Schilling (1971), and O'Nions and Clarke (1972). The general form to which all these equations reduce is presented, and an analysis is performed to demonstrate their mathematical equivalence. It is noted that the utility of the general equation flows from the nature of equilibrium (i.e., the final state is independent of the path by which that state is attained).

A general equilibrium model of ecosystem services in a river basin

Treesearch

Travis Warziniack

2014-01-01

This study builds a general equilibrium model of ecosystem services, with sectors of the economy competing for use of the environment. The model recognizes that production processes in the real world require a combination of natural and human inputs, and understanding the value of these inputs and their competing uses is necessary when considering policies of resource...

Are Equity and Efficiency Irreconcilable Goals in Education? A General Equilibrium Analysis of Basic Education Finance in China

ERIC Educational Resources Information Center

Ding, Weili; Lu, Ming

2007-01-01

Lacking guidance of general equilibrium (GE) theories in public economics and the corresponding proper mechanisms, China has not surprisingly witnessed an inequality in educational expenditures across regions as well as insufficiency of funds for education in poor areas. It is wrongly thought that what happens is due to the decentralized financing…

A generalized chemistry version of SPARK

NASA Technical Reports Server (NTRS)

Carpenter, Mark H.

1988-01-01

An extension of the reacting H2-air computer code SPARK is presented, which enables the code to be used on any reacting flow problem. Routines are developed calculating in a general fashion, the reaction rates, and chemical Jacobians of any reacting system. In addition, an equilibrium routine is added so that the code will have frozen, finite rate, and equilibrium capabilities. The reaction rate for the species is determined from the law of mass action using Arrhenius expressions for the rate constants. The Jacobian routines are determined by numerically or analytically differentiating the law of mass action for each species. The equilibrium routine is based on a Gibbs free energy minimization routine. The routines are written in FORTRAN 77, with special consideration given to vectorization. Run times for the generalized routines are generally 20 percent slower than reaction specific routines. The numerical efficiency of the generalized analytical Jacobian, however, is nearly 300 percent better than the reaction specific numerical Jacobian used in SPARK.

Bioproducts and environmental quality: Biofuels, greenhouse gases, and water quality

NASA Astrophysics Data System (ADS)

Ren, Xiaolin

Promoting bio-based products is one oft-proposed solution to reduce GHG emissions because the feedstocks capture carbon, offsetting at least partially the carbon discharges resulting from use of the products. However, several life cycle analyses point out that while biofuels may emit less life cycle net carbon emissions than fossil fuels, they may exacerbate other parts of biogeochemical cycles, notably nutrient loads in the aquatic environment. In three essays, this dissertation explores the tradeoff between GHG emissions and nitrogen leaching associated with biofuel production using general equilibrium models. The first essay develops a theoretical general equilibrium model to calculate the second-best GHG tax with the existence of a nitrogen leaching distortion. The results indicate that the second-best GHG tax could be higher or lower than the first-best tax rates depending largely on the elasticity of substitution between fossil fuel and biofuel. The second and third essays employ computable general equilibrium models to further explore the tradeoff between GHG emissions and nitrogen leaching. The computable general equilibrium models also incorporate multiple biofuel pathways, i.e., biofuels made from different feedstocks using different processes, to identify the cost-effective combinations of biofuel pathways under different policies, and the corresponding economic and environmental impacts.

Teaching Chemical Equilibrium and Thermodynamics in Undergraduate General Chemistry Classes.

ERIC Educational Resources Information Center

Banerjee, Anil C.

1995-01-01

Discusses some of the conceptual difficulties encountered by undergraduate students in learning certain aspects of chemical equilibrium and thermodynamics. Discusses teaching strategies for dealing with these difficulties. (JRH)

14 CFR 29.471 - General.

Code of Federal Regulations, 2010 CFR

2010-01-01

... equilibrium. For limit ground loads— (1) The limit ground loads obtained in the landing conditions in this... equilibrium with linear and angular inertia loads in a rational or conservative manner. (b) Critical centers...

Finite-deformation phase-field chemomechanics for multiphase, multicomponent solids

NASA Astrophysics Data System (ADS)

Svendsen, Bob; Shanthraj, Pratheek; Raabe, Dierk

2018-03-01

The purpose of this work is the development of a framework for the formulation of geometrically non-linear inelastic chemomechanical models for a mixture of multiple chemical components diffusing among multiple transforming solid phases. The focus here is on general model formulation. No specific model or application is pursued in this work. To this end, basic balance and constitutive relations from non-equilibrium thermodynamics and continuum mixture theory are combined with a phase-field-based description of multicomponent solid phases and their interfaces. Solid phase modeling is based in particular on a chemomechanical free energy and stress relaxation via the evolution of phase-specific concentration fields, order-parameter fields (e.g., related to chemical ordering, structural ordering, or defects), and local internal variables. At the mixture level, differences or contrasts in phase composition and phase local deformation in phase interface regions are treated as mixture internal variables. In this context, various phase interface models are considered. In the equilibrium limit, phase contrasts in composition and local deformation in the phase interface region are determined via bulk energy minimization. On the chemical side, the equilibrium limit of the current model formulation reduces to a multicomponent, multiphase, generalization of existing two-phase binary alloy interface equilibrium conditions (e.g., KKS). On the mechanical side, the equilibrium limit of one interface model considered represents a multiphase generalization of Reuss-Sachs conditions from mechanical homogenization theory. Analogously, other interface models considered represent generalizations of interface equilibrium conditions consistent with laminate and sharp-interface theory. In the last part of the work, selected existing models are formulated within the current framework as special cases and discussed in detail.

General equilibrium characteristics of a dual-lift helicopter system

NASA Technical Reports Server (NTRS)

Cicolani, L. S.; Kanning, G.

1986-01-01

The equilibrium characteristics of a dual-lift helicopter system are examined. The system consists of the cargo attached by cables to the endpoints of a spreader bar which is suspended by cables below two helicopters. Results are given for the orientation angles of the suspension system and its internal forces, and for the helicopter thrust vector requirements under general circumstances, including nonidentical helicopters, any accelerating or static equilibrium reference flight condition, any system heading relative to the flight direction, and any distribution of the load to the two helicopters. Optimum tether angles which minimize the sum of the required thrust magnitudes are also determined. The analysis does not consider the attitude degrees of freedom of the load and helicopters in detail, but assumes that these bodies are stable, and that their aerodynamic forces in equilibrium flight can be determined independently as functions of the reference trajectory. The ranges of these forces for sample helicopters and loads are examined and their effects on the equilibrium characteristics are given parametrically in the results.

Effect of a Perturbation on the Chemical Equilibrium: Comparison with Le Châtelier's Principle

NASA Astrophysics Data System (ADS)

Martínez Torres, Emilio

2007-03-01

This article develops a general thermodynamic treatment to predict the direction of shift in a chemical equilibrium when it is subjected to a stress. This treatment gives an inequality that relates the change in the perturbed variable and the change that the equilibrium shift produces in the conjugated variable. To illustrate the generality of this approach, it has been applied to predict the direction of shift caused by changes of pressure, volume, and amount of substance. In this last case, the well-known unexpected shift in the ammonia synthesis equilibrium upon addition of nitrogen is easily explained. From the above referred inequality and the stability criteria of thermodynamics some conclusions have been obtained about the direction of shift in terms of extensive and extensive variables. This article is suitable for physical chemistry courses.

Universal laws of human society's income distribution

NASA Astrophysics Data System (ADS)

Tao, Yong

2015-10-01

General equilibrium equations in economics play the same role with many-body Newtonian equations in physics. Accordingly, each solution of the general equilibrium equations can be regarded as a possible microstate of the economic system. Since Arrow's Impossibility Theorem and Rawls' principle of social fairness will provide a powerful support for the hypothesis of equal probability, then the principle of maximum entropy is available in a just and equilibrium economy so that an income distribution will occur spontaneously (with the largest probability). Remarkably, some scholars have observed such an income distribution in some democratic countries, e.g. USA. This result implies that the hypothesis of equal probability may be only suitable for some "fair" systems (economic or physical systems). From this meaning, the non-equilibrium systems may be "unfair" so that the hypothesis of equal probability is unavailable.

Condition of Mechanical Equilibrium at the Phase Interface with Arbitrary Geometry

NASA Astrophysics Data System (ADS)

Zubkov, V. V.; Zubkova, A. V.

2017-09-01

The authors produced an expression for the mechanical equilibrium condition at the phase interface within the force definition of surface tension. This equilibrium condition is the most general one from the mathematical standpoint and takes into account the three-dimensional aspect of surface tension. Furthermore, the formula produced allows describing equilibrium on the fractal surface of the interface. The authors used the fractional integral model of fractal distribution and took the fractional order integrals over Euclidean space instead of integrating over the fractal set.

Flux Jacobian Matrices For Equilibrium Real Gases

NASA Technical Reports Server (NTRS)

Vinokur, Marcel

1990-01-01

Improved formulation includes generalized Roe average and extension to three dimensions. Flux Jacobian matrices derived for use in numerical solutions of conservation-law differential equations of inviscid flows of ideal gases extended to real gases. Real-gas formulation of these matrices retains simplifying assumptions of thermodynamic and chemical equilibrium, but adds effects of vibrational excitation, dissociation, and ionization of gas molecules via general equation of state.

Nonlinear Viscoelastic Mechanics of Cross-linked Rubbers

NASA Technical Reports Server (NTRS)

Freed, Alan D.; Leonov, Arkady I.; Gray, Hugh R. (Technical Monitor)

2002-01-01

The paper develops a general theory for finite rubber viscoelasticity, and specifies it in the form, convenient for solving problems important for rubber, tire and space industries. Based on the quasi-linear approach of non-equilibrium thermodynamics, a general nonlinear theory has been developed for arbitrary nonisothermal deformations of viscoelastic solids. In this theory, the constitutive equations are presented as the sum of known equilibrium (rubber elastic) and non-equilibrium (liquid polymer viscoelastic) terms. These equations are then simplified using several modeling arguments. Stability constraints for the proposed constitutive equations are also discussed. It is shown that only strong ellipticity criteria are applicable for assessing stability of the equations governing viscoelastic solids.

A Thermodynamic Theory of Solid Viscoelasticity. Part II:; Nonlinear Thermo-viscoelasticity

NASA Technical Reports Server (NTRS)

Freed, Alan D.; Leonov, Arkady I.; Gray, Hugh R. (Technical Monitor)

2002-01-01

This paper, second in the series of three papers, develops a general, nonlinear, non-isothermal, compressible theory for finite rubber viscoelasticity and specifies it in a form convenient for solving problems important to the rubber, tire, automobile, and air-space industries, among others. Based on the quasi-linear approach of non-equilibrium thermodynamics, a general nonlinear theory of differential type has been developed for arbitrary non-isothermal deformations of viscoelastic solids. In this theory, the constitutive equations were presented as the sum of a rubber elastic (equilibrium) and a liquid type viscoelastic (non-equilibrium) terms. These equations have then been simplified using several modeling and simplicity arguments.

Child allowances, fertility, and chaotic dynamics.

PubMed

Chen, Hung-Ju; Li, Ming-Chia

2013-06-01

This paper analyzes the dynamics in an overlapping generations model with the provision of child allowances. Fertility is an increasing function of child allowances and there exists a threshold effect of the marginal effect of child allowances on fertility. We show that if the effectiveness of child allowances is sufficiently high, an intermediate-sized tax rate will be enough to generate chaotic dynamics. Besides, a decrease in the inter-temporal elasticity of substitution will prevent the occurrence of irregular cycles.

Pensions and Intertemporal Choice: Evidence from the U.S. Military

DTIC Science & Technology

2014-02-01

to rise to $116.9 billion by 2035 (Office of the Actuary , 2013). In response to these rising costs, the National Defense Authoriza- tion Act of 2000...Discount rates inferred from deci- sions: An experimental study,” Management science , 1989, 35 (3), 270–284. Beshears, John, James J Choi, David...1149–1187. Office of the Actuary , “Statistical Report on the Military Retirement System for Fiscal Year 2012,” US Department of Defense, 2013. Ruderman

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Wei; Wang, Jin, E-mail: jin.wang.1@stonybrook.edu; State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022 Changchun, China and College of Physics, Jilin University, 130021 Changchun

We have established a general non-equilibrium thermodynamic formalism consistently applicable to both spatially homogeneous and, more importantly, spatially inhomogeneous systems, governed by the Langevin and Fokker-Planck stochastic dynamics with multiple state transition mechanisms, using the potential-flux landscape framework as a bridge connecting stochastic dynamics with non-equilibrium thermodynamics. A set of non-equilibrium thermodynamic equations, quantifying the relations of the non-equilibrium entropy, entropy flow, entropy production, and other thermodynamic quantities, together with their specific expressions, is constructed from a set of dynamical decomposition equations associated with the potential-flux landscape framework. The flux velocity plays a pivotal role on both the dynamic andmore » thermodynamic levels. On the dynamic level, it represents a dynamic force breaking detailed balance, entailing the dynamical decomposition equations. On the thermodynamic level, it represents a thermodynamic force generating entropy production, manifested in the non-equilibrium thermodynamic equations. The Ornstein-Uhlenbeck process and more specific examples, the spatial stochastic neuronal model, in particular, are studied to test and illustrate the general theory. This theoretical framework is particularly suitable to study the non-equilibrium (thermo)dynamics of spatially inhomogeneous systems abundant in nature. This paper is the second of a series.« less

Semiexperimental equilibrium structures for building blocks of organic and biological molecules: the B2PLYP route.

PubMed

Penocchio, Emanuele; Piccardo, Matteo; Barone, Vincenzo

2015-10-13

The B2PLYP double hybrid functional, coupled with the correlation-consistent triple-ζ cc-pVTZ (VTZ) basis set, has been validated in the framework of the semiexperimental (SE) approach for deriving accurate equilibrium structures of molecules containing up to 15 atoms. A systematic comparison between new B2PLYP/VTZ results and several equilibrium SE structures previously determined at other levels, in particular B3LYP/SNSD and CCSD(T) with various basis sets, has put in evidence the accuracy and the remarkable stability of such model chemistry for both equilibrium structures and vibrational corrections. New SE equilibrium structures for phenylacetylene, pyruvic acid, peroxyformic acid, and phenyl radical are discussed and compared with literature data. Particular attention has been devoted to the discussion of systems for which lack of sufficient experimental data prevents a complete SE determination. In order to obtain an accurate equilibrium SE structure for these situations, the so-called templating molecule approach is discussed and generalized with respect to our previous work. Important applications are those involving biological building blocks, like uracil and thiouracil. In addition, for more general situations the linear regression approach has been proposed and validated.

Hyperbolic Discounting: Value and Time Processes of Substance Abusers and Non-Clinical Individuals in Intertemporal Choice

PubMed Central

2014-01-01

The single parameter hyperbolic model has been frequently used to describe value discounting as a function of time and to differentiate substance abusers and non-clinical participants with the model's parameter k. However, k says little about the mechanisms underlying the observed differences. The present study evaluates several alternative models with the purpose of identifying whether group differences stem from differences in subjective valuation, and/or time perceptions. Using three two-parameter models, plus secondary data analyses of 14 studies with 471 indifference point curves, results demonstrated that adding a valuation, or a time perception function led to better model fits. However, the gain in fit due to the flexibility granted by a second parameter did not always lead to a better understanding of the data patterns and corresponding psychological processes. The k parameter consistently indexed group and context (magnitude) differences; it is thus a mixed measure of person and task level effects. This was similar for a parameter meant to index payoff devaluation. A time perception parameter, on the other hand, fluctuated with contexts in a non-predicted fashion and the interpretation of its values was inconsistent with prior findings that supported enlarged perceived delays for substance abusers compared to controls. Overall, the results provide mixed support for hyperbolic models of intertemporal choice in terms of the psychological meaning afforded by their parameters. PMID:25390941

Generalized thermodynamic relations for a system experiencing heat and mass diffusion in the far-from-equilibrium realm based on steepest entropy ascent.

PubMed

Li, Guanchen; von Spakovsky, Michael R

2016-09-01

This paper presents a nonequilibrium thermodynamic model for the relaxation of a local, isolated system in nonequilibrium using the principle of steepest entropy ascent (SEA), which can be expressed as a variational principle in thermodynamic state space. The model is able to arrive at the Onsager relations for such a system. Since no assumption of local equilibrium is made, the conjugate fluxes and forces are intrinsic to the subspaces of the system's state space and are defined using the concepts of hypoequilibrium state and nonequilibrium intensive properties, which describe the nonmutual equilibrium status between subspaces of the thermodynamic state space. The Onsager relations are shown to be a thermodynamic kinematic feature of the system independent of the specific details of the micromechanical dynamics. Two kinds of relaxation processes are studied with different constraints (i.e., conservation laws) corresponding to heat and mass diffusion. Linear behavior in the near-equilibrium region as well as nonlinear behavior in the far-from-equilibrium region are discussed. Thermodynamic relations in the equilibrium and near-equilibrium realm, including the Gibbs relation, the Clausius inequality, and the Onsager relations, are generalized to the far-from-equilibrium realm. The variational principle in the space spanned by the intrinsic conjugate fluxes and forces is expressed via the quadratic dissipation potential. As an application, the model is applied to the heat and mass diffusion of a system represented by a single-particle ensemble, which can also be applied to a simple system of many particles. Phenomenological transport coefficients are also derived in the near-equilibrium realm.

Applicability of Markets to Global Scheduling in Grids: Critical Examination of General Equilibrium Theory and Market Folklore

NASA Technical Reports Server (NTRS)

Nakai, Junko; VanDerWijngaart, Rob F.

2003-01-01

Markets are often considered superior to other global scheduling mechanisms for distributed computing systems. This claim is supported by: a casual observation from our every-day life that markets successfully equilibrate supply and demand, and the features of markets which originate in the general equilibrium theory, e.g., efficiency and the lack of necessity of 2 central controller. This paper describes why such beliefs in markets are not warranted. It does so by examining the general equilibrium theory, in terms of scope, abstraction, and interpretation. Not only does the general equilibrium theory fail to provide a satisfactory explanation of actual economies, including a computing-resource economy, it also falls short of supplying theoretical foundations for commonly held views of market desirability. This paper also points out that the argument for the desirability of markets involves circular reasoning and that the desirability can be established only vis-a-vis a scheduling goal. Finally, recasting the conclusion of Arrow's Impossibility Theorem as that for global scheduling, we conclude that there exists no market-based scheduler that is rational (in the sense defined in microeconomic theory), takes into account utility of more than one user, and yet yields a Pareto-optimal outcome for arbitrary user utility functions.

A survey of upwind methods for flows with equilibrium and non-equilibrium chemistry and thermodynamics

NASA Technical Reports Server (NTRS)

Grossman, B.; Garrett, J.; Cinnella, P.

1989-01-01

Several versions of flux-vector split and flux-difference split algorithms were compared with regard to general applicability and complexity. Test computations were performed using curve-fit equilibrium air chemistry for an M = 5 high-temperature inviscid flow over a wedge, and an M = 24.5 inviscid flow over a blunt cylinder for test computations; for these cases, little difference in accuracy was found among the versions of the same flux-split algorithm. For flows with nonequilibrium chemistry, the effects of the thermodynamic model on the development of flux-vector split and flux-difference split algorithms were investigated using an equilibrium model, a general nonequilibrium model, and a simplified model based on vibrational relaxation. Several numerical examples are presented, including nonequilibrium air chemistry in a high-temperature shock tube and nonequilibrium hydrogen-air chemistry in a supersonic diffuser.

Answer Sets in a Fuzzy Equilibrium Logic

NASA Astrophysics Data System (ADS)

Schockaert, Steven; Janssen, Jeroen; Vermeir, Dirk; de Cock, Martine

Since its introduction, answer set programming has been generalized in many directions, to cater to the needs of real-world applications. As one of the most general “classical” approaches, answer sets of arbitrary propositional theories can be defined as models in the equilibrium logic of Pearce. Fuzzy answer set programming, on the other hand, extends answer set programming with the capability of modeling continuous systems. In this paper, we combine the expressiveness of both approaches, and define answer sets of arbitrary fuzzy propositional theories as models in a fuzzification of equilibrium logic. We show that the resulting notion of answer set is compatible with existing definitions, when the syntactic restrictions of the corresponding approaches are met. We furthermore locate the complexity of the main reasoning tasks at the second level of the polynomial hierarchy. Finally, as an illustration of its modeling power, we show how fuzzy equilibrium logic can be used to find strong Nash equilibria.

Isobaric molecular dynamics version of the generalized replica exchange method (gREM): Liquid–vapor equilibrium

DOE PAGES

Malolepsza, Edyta; Secor, Maxim; Keyes, Tom

2015-09-23

A prescription for sampling isobaric generalized ensembles with molecular dynamics is presented and applied to the generalized replica exchange method (gREM), which was designed for simulating first-order phase transitions. The properties of the isobaric gREM ensemble are discussed and a study is presented of the liquid-vapor equilibrium of the guest molecules given for gas hydrate formation with the mW water model. As a result, phase diagrams, critical parameters, and a law of corresponding states are obtained.

H theorem for generalized entropic forms within a master-equation framework

NASA Astrophysics Data System (ADS)

Casas, Gabriela A.; Nobre, Fernando D.; Curado, Evaldo M. F.

2016-03-01

The H theorem is proven for generalized entropic forms, in the case of a discrete set of states. The associated probability distributions evolve in time according to a master equation, for which the corresponding transition rates depend on these entropic forms. An important equation describing the time evolution of the transition rates and probabilities in such a way as to drive the system towards an equilibrium state is found. In the particular case of Boltzmann-Gibbs entropy, it is shown that this equation is satisfied in the microcanonical ensemble only for symmetric probability transition rates, characterizing a single path to the equilibrium state. This equation fulfils the proof of the H theorem for generalized entropic forms, associated with systems characterized by complex dynamics, e.g., presenting nonsymmetric probability transition rates and more than one path towards the same equilibrium state. Some examples considering generalized entropies of the literature are discussed, showing that they should be applicable to a wide range of natural phenomena, mainly those within the realm of complex systems.

Generalized adsorption isotherms for molecular and dissociative adsorption of a polar molecular species on two polar surface geometries: Perovskite (100) (Pm-3m) and fluorite (111) (Fm-3m)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Danielson, Thomas; Hin, Celine; Savara, Aditya

Lattice based kinetic Monte Carlo (KMC) simulations have been used to determine a functional form for the second order adsorption isotherms on two commonly investigated crystal surfaces: the (111) fluorite surface and the (100) perovskite surface which has the same geometric symmetry as the NaCl (100) surface. The functional form is generalized to be applicable to all values of the equilibrium constant by a shift along the pressure axis. Functions have been determined for estimating the pressure at which a desired coverage would be achieved and for estimating the coverage at a certain pressure. The generalized form has been calculatedmore » by investigating the surface adsorbate coverage across a range of thermodynamic equilibrium constants that span the range 10-26 to 1013. Finally, the equations have been shown to be general for any value of the adsorption equilibrium constant.« less

Generalized adsorption isotherms for molecular and dissociative adsorption of a polar molecular species on two polar surface geometries: Perovskite (100) (Pm-3m) and fluorite (111) (Fm-3m)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Danielson, Thomas; Hin, Celine; Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061

Lattice based kinetic Monte Carlo simulations have been used to determine a functional form for the second order adsorption isotherms on two commonly investigated crystal surfaces: the (111) fluorite surface and the (100) perovskite surface which has the same geometric symmetry as the NaCl (100) surface. The functional form is generalized to be applicable to all values of the equilibrium constant by a shift along the pressure axis. Functions have been determined for estimating the pressure at which a desired coverage would be achieved and, conversely, for estimating the coverage at a certain pressure. The generalized form has been calculatedmore » by investigating the surface adsorbate coverage across a range of thermodynamic equilibrium constants that span the range 10{sup −26} to 10{sup 13}. The equations have been shown to be general for any value of the adsorption equilibrium constant.« less

Generalized adsorption isotherms for molecular and dissociative adsorption of a polar molecular species on two polar surface geometries: Perovskite (100) (Pm-3m) and fluorite (111) (Fm-3m)

DOE PAGES

Danielson, Thomas; Hin, Celine; Savara, Aditya

2016-08-10

Lattice based kinetic Monte Carlo (KMC) simulations have been used to determine a functional form for the second order adsorption isotherms on two commonly investigated crystal surfaces: the (111) fluorite surface and the (100) perovskite surface which has the same geometric symmetry as the NaCl (100) surface. The functional form is generalized to be applicable to all values of the equilibrium constant by a shift along the pressure axis. Functions have been determined for estimating the pressure at which a desired coverage would be achieved and for estimating the coverage at a certain pressure. The generalized form has been calculatedmore » by investigating the surface adsorbate coverage across a range of thermodynamic equilibrium constants that span the range 10-26 to 1013. Finally, the equations have been shown to be general for any value of the adsorption equilibrium constant.« less

Equilibrium econophysics: A unified formalism for neoclassical economics and equilibrium thermodynamics

NASA Astrophysics Data System (ADS)

Sousa, Tânia; Domingos, Tiago

2006-11-01

We develop a unified conceptual and mathematical structure for equilibrium econophysics, i.e., the use of concepts and tools of equilibrium thermodynamics in neoclassical microeconomics and vice versa. Within this conceptual structure the results obtained in microeconomic theory are: (1) the definition of irreversibility in economic behavior; (2) the clarification that the Engel curve and the offer curve are not descriptions of real processes dictated by the maximization of utility at constant endowment; (3) the derivation of a relation between elasticities proving that economic elasticities are not all independent; (4) the proof that Giffen goods do not exist in a stable equilibrium; (5) the derivation that ‘economic integrability’ is equivalent to the generalized Le Chatelier principle and (6) the definition of a first order phase transition, i.e., a transition between separate points in the utility function. In thermodynamics the results obtained are: (1) a relation between the non-dimensional isothermal and adiabatic compressibilities and the increase or decrease in the thermodynamic potentials; (2) the distinction between mathematical integrability and optimization behavior and (3) the generalization of the Clapeyron equation.

Cross-cultural comparisons of delay discounting of gain and loss.

PubMed

Ishii, Keiko; Gang, Lili; Takahashi, Taiki

2016-11-01

People generally tend to discount future outcomes in favor of smaller but immediate gains (i.e., delay discounting). The present research examined cultural similarities and differences in delay discounting of gain and loss between Chinese and Japanese, based on a q-exponential model of intertemporal choice. Using a hypothetical situation, we asked 65 Japanese participants and 51 Chinese participants to choose between receiving (or paying) a different amount of money immediately or with a specified delay (1 week, 2 weeks, 1 month, 6 months, 1 year, 5 years, and 25 years). For each delay, participants completed a series of 40 binary choices for gain or loss. Regardless of cultures, the q-exponential model was the optimal model. Both impulsivity and time-inconsistency were higher for future gains than for future losses. In addition to the cultural similarities, Chinese participants discounted future gains and losses more steeply than did Japanese. In contrast, Japanese participants were more time-inconsistent in delay discounting than were Chinese, suggesting that the reduction in their subjective value depended relatively on delay.

A General Method for Automatic Computation of Equilibrium Compositions and Theoretical Rocket Performance of Propellants

NASA Technical Reports Server (NTRS)

Gordon, Sanford; Zeleznik, Frank J.; Huff, Vearl N.

1959-01-01

A general computer program for chemical equilibrium and rocket performance calculations was written for the IBM 650 computer with 2000 words of drum storage, 60 words of high-speed core storage, indexing registers, and floating point attachments. The program is capable of carrying out combustion and isentropic expansion calculations on a chemical system that may include as many as 10 different chemical elements, 30 reaction products, and 25 pressure ratios. In addition to the equilibrium composition, temperature, and pressure, the program calculates specific impulse, specific impulse in vacuum, characteristic velocity, thrust coefficient, area ratio, molecular weight, Mach number, specific heat, isentropic exponent, enthalpy, entropy, and several thermodynamic first derivatives.

Global stability of a multiple delayed viral infection model with general incidence rate and an application to HIV infection.

PubMed

Ji, Yu

2015-06-01

In this paper, the dynamical behavior of a viral infection model with general incidence rate and two time delays is studied. By using the Lyapunov functional and LaSalle invariance principle, the global stabilities of the infection-free equilibrium and the endemic equilibrium are obtained. We obtain a threshold of the global stability for the uninfected equilibrium, which means the disease will be under control eventually. These results can be applied to a variety of viral infections of disease that would make it possible to devise optimal treatment strategies. Numerical simulations with application to HIV infection are given to verify the analytical results.

Studying non-equilibrium many-body dynamics using one-dimensional Bose gases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Langen, Tim; Gring, Michael; Kuhnert, Maximilian

2014-12-04

Non-equilibrium dynamics of isolated quantum many-body systems play an important role in many areas of physics. However, a general answer to the question of how these systems relax is still lacking. We experimentally study the dynamics of ultracold one-dimensional (1D) Bose gases. This reveals the existence of a quasi-steady prethermalized state which differs significantly from the thermal equilibrium of the system. Our results demonstrate that the dynamics of non-equilibrium quantum many-body systems is a far richer process than has been assumed in the past.

Shape characteristics of equilibrium and non-equilibrium fractal clusters.

PubMed

Mansfield, Marc L; Douglas, Jack F

2013-07-28

It is often difficult in practice to discriminate between equilibrium and non-equilibrium nanoparticle or colloidal-particle clusters that form through aggregation in gas or solution phases. Scattering studies often permit the determination of an apparent fractal dimension, but both equilibrium and non-equilibrium clusters in three dimensions frequently have fractal dimensions near 2, so that it is often not possible to discriminate on the basis of this geometrical property. A survey of the anisotropy of a wide variety of polymeric structures (linear and ring random and self-avoiding random walks, percolation clusters, lattice animals, diffusion-limited aggregates, and Eden clusters) based on the principal components of both the radius of gyration and electric polarizability tensor indicates, perhaps counter-intuitively, that self-similar equilibrium clusters tend to be intrinsically anisotropic at all sizes, while non-equilibrium processes such as diffusion-limited aggregation or Eden growth tend to be isotropic in the large-mass limit, providing a potential means of discriminating these clusters experimentally if anisotropy could be determined along with the fractal dimension. Equilibrium polymer structures, such as flexible polymer chains, are normally self-similar due to the existence of only a single relevant length scale, and are thus anisotropic at all length scales, while non-equilibrium polymer structures that grow irreversibly in time eventually become isotropic if there is no difference in the average growth rates in different directions. There is apparently no proof of these general trends and little theoretical insight into what controls the universal anisotropy in equilibrium polymer structures of various kinds. This is an obvious topic of theoretical investigation, as well as a matter of practical interest. To address this general problem, we consider two experimentally accessible ratios, one between the hydrodynamic and gyration radii, the other between the viscosity and hydrodynamic radii, as potential measures of shape anisotropy. We also find a strong correlation between anisotropy and effective fractal dimension. These observations should provide new practical methods for quantifying the nature of particle clustering in diverse contexts.

Implementation of Premixed Equilibrium Chemistry Capability in OVERFLOW

NASA Technical Reports Server (NTRS)

Olsen, M. E.; Liu, Y.; Vinokur, M.; Olsen, T.

2003-01-01

An implementation of premixed equilibrium chemistry has been completed for the OVERFLOW code, a chimera capable, complex geometry flow code widely used to predict transonic flowfields. The implementation builds on the computational efficiency and geometric generality of the solver.

Implementation of Premixed Equilibrium Chemistry Capability in OVERFLOW

NASA Technical Reports Server (NTRS)

Olsen, Mike E.; Liu, Yen; Vinokur, M.; Olsen, Tom

2004-01-01

An implementation of premixed equilibrium chemistry has been completed for the OVERFLOW code, a chimera capable, complex geometry flow code widely used to predict transonic flowfields. The implementation builds on the computational efficiency and geometric generality of the solver.

Social Identity and Preferences*

PubMed Central

Benjamin, Daniel J.; Choi, James J.; Strickland, A. Joshua

2009-01-01

Social identities prescribe behaviors for people. We identify the marginal behavioral effect of these norms on discount rates and risk aversion by measuring how laboratory subjects’ choices change when an aspect of social identity is made salient. When we make ethnic identity salient to Asian-American subjects, they make more patient choices. When we make racial identity salient to black subjects, non-immigrant blacks (but not immigrant blacks) make more patient choices. Making gender identity salient has no effect on intertemporal or risk choices. PMID:20871741

Non-equilibrium thermodynamics, maximum entropy production and Earth-system evolution.

PubMed

Kleidon, Axel

2010-01-13

The present-day atmosphere is in a unique state far from thermodynamic equilibrium. This uniqueness is for instance reflected in the high concentration of molecular oxygen and the low relative humidity in the atmosphere. Given that the concentration of atmospheric oxygen has likely increased throughout Earth-system history, we can ask whether this trend can be generalized to a trend of Earth-system evolution that is directed away from thermodynamic equilibrium, why we would expect such a trend to take place and what it would imply for Earth-system evolution as a whole. The justification for such a trend could be found in the proposed general principle of maximum entropy production (MEP), which states that non-equilibrium thermodynamic systems maintain steady states at which entropy production is maximized. Here, I justify and demonstrate this application of MEP to the Earth at the planetary scale. I first describe the non-equilibrium thermodynamic nature of Earth-system processes and distinguish processes that drive the system's state away from equilibrium from those that are directed towards equilibrium. I formulate the interactions among these processes from a thermodynamic perspective and then connect them to a holistic view of the planetary thermodynamic state of the Earth system. In conclusion, non-equilibrium thermodynamics and MEP have the potential to provide a simple and holistic theory of Earth-system functioning. This theory can be used to derive overall evolutionary trends of the Earth's past, identify the role that life plays in driving thermodynamic states far from equilibrium, identify habitability in other planetary environments and evaluate human impacts on Earth-system functioning. This journal is © 2010 The Royal Society

Existence and Hadamard well-posedness of a system of simultaneous generalized vector quasi-equilibrium problems.

PubMed

Zhang, Wenyan; Zeng, Jing

2017-01-01

An existence result for the solution set of a system of simultaneous generalized vector quasi-equilibrium problems (for short, (SSGVQEP)) is obtained, which improves Theorem 3.1 of the work of Ansari et al. (J. Optim. Theory Appl. 127:27-44, 2005). Moreover, a definition of Hadamard-type well-posedness for (SSGVQEP) is introduced and sufficient conditions for Hadamard well-posedness of (SSGVQEP) are established.

On the equilibrium structures of self-gravitating masses of gas containing axisymmetric magnetic fields

NASA Technical Reports Server (NTRS)

Lerche, I.; Low, B. C.

1980-01-01

The general equations describing the equilibrium shapes of self-gravitating gas clouds containing axisymmetric magnetic fields are presented. The general equations admit of a large class of solutions. It is shown that if one additional (ad hoc) asumption is made that the mass be spherically symmetrically distributed, then the gas pressure and the boundary conditions are sufficiently constraining that the general topological structure of the solution is effectively determined. The further assumption of isothermal conditions for this case demands that all solutions possess force-free axisymmetric magnetic fields. It is also shown how the construction of aspherical (but axisymmetric) configurations can be achieved in some special cases, and it is demonstrated that the detailed form of the possible equilibrium shapes depends upon the arbitrary choice of the functional form of the variation of the gas pressure along the field lines.

Metric of two balancing Kerr particles in physical parametrization

NASA Astrophysics Data System (ADS)

Manko, V. S.; Ruiz, E.

2015-11-01

The present paper aims at elaborating a completely physical representation for the general 4-parameter family of the extended double-Kerr spacetimes describing two spinning sources in gravitational equilibrium. This involved problem is solved in a concise analytical form by using the individual Komar masses and angular momenta as arbitrary parameters, and the simplest equatorially symmetric specialization of the general expressions obtained by us yields the physical representation for the well-known Dietz-Hoenselaers superextreme case of two balancing identical Kerr constituents. The existence of the physically meaningful "black-hole-superextreme-object" equilibrium configurations permitted by the general solution may be considered as a clear indication that the spin-spin repulsion force might actually be by far stronger than expected earlier, when only the balance between two superextreme Kerr sources was thought possible. We also present the explicit analytical formulas relating the equilibrium states in the double-Kerr and double-Reissner-Nordström configurations.

General equilibrium incidence of energy taxation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solow, J.L.

1984-04-01

The pervasiveness of energy in the economy and the numerous ways in which energy taxation can distort resource allocations implies the necessity of a general equilibrium approach to the question of energy tax incidence. The author presents a general equilibrium model that accounts for domestic energy production and energy imports, direct energy consumption and use of energy as an intermediate good, and production of energy intensive and nonenergy intensive goods. He examines the incidence of three broadly-based energy taxation policies: a tax on all energy consumption, a subsidy to domestic energy production, and a tariff on energy imports. The subsidy,more » although not a revenue raising measure, is included because, like the other policies, it acts to reduce energy imports. Such a measure may be of interest by reducing reliance on unstable foreign sources of supply. 12 references, 3 tables.« less

Spontaneity and Equilibrium: Why "?G < 0 Denotes a Spontaneous Process" and "?G = 0 Means the System Is at Equilibrium" Are Incorrect

ERIC Educational Resources Information Center

Raff, Lionel M.

2014-01-01

The fundamental criteria for chemical reactions to be spontaneous in a given direction are generally incorrectly stated as ?G < 0 or ?A < 0 in most introductory chemistry textbooks and even in some more advanced texts. Similarly, the criteria for equilibrium are also misstated as being ?G = 0 or ?A = 0. Following a brief review of the…

Equilibrium Distribution Functions: Another Look.

ERIC Educational Resources Information Center

Waite, Boyd A.

1986-01-01

Discusses equilibrium distribution functions and provides an alternative "derivation" that allows the student, with the help of a computer, to gain intuitive insight as to the nature of distributions in general and the precise nature of the dominance of the Boltzmann distribution. (JN)

Dynamic relaxation of a levitated nanoparticle from a non-equilibrium steady state.

PubMed

Gieseler, Jan; Quidant, Romain; Dellago, Christoph; Novotny, Lukas

2014-05-01

Fluctuation theorems are a generalization of thermodynamics on small scales and provide the tools to characterize the fluctuations of thermodynamic quantities in non-equilibrium nanoscale systems. They are particularly important for understanding irreversibility and the second law in fundamental chemical and biological processes that are actively driven, thus operating far from thermal equilibrium. Here, we apply the framework of fluctuation theorems to investigate the important case of a system relaxing from a non-equilibrium state towards equilibrium. Using a vacuum-trapped nanoparticle, we demonstrate experimentally the validity of a fluctuation theorem for the relative entropy change occurring during relaxation from a non-equilibrium steady state. The platform established here allows non-equilibrium fluctuation theorems to be studied experimentally for arbitrary steady states and can be extended to investigate quantum fluctuation theorems as well as systems that do not obey detailed balance.

Three dimensional PNS solutions of hypersonic internal flows with equilibrium chemistry

NASA Technical Reports Server (NTRS)

Liou, May-Fun

1989-01-01

An implicit procedure for solving parabolized Navier-Stokes equations under the assumption of a general equation of state for a gas in chemical equilibrium is given. A general and consistent approach for the evaluation of Jacobian matrices in the implicit operator avoids the use of unnecessary auxiliary quantities and approximations, and leads to a simple expression. Applications to two- and three-dimensional flow problems show efficiency in computer time and economy in storage.

Perturbative Out of Equilibrium Quantum Field Theory beyond the Gradient Approximation and Generalized Boltzmann Equation

NASA Astrophysics Data System (ADS)

Ozaki, H.

2004-01-01

Using the closed-time-path formalism, we construct perturbative frameworks, in terms of quasiparticle picture, for studying quasiuniform relativistic quantum field systems near equilibrium and non-equilibrium quasistationary systems. We employ the derivative expansion and take in up to the second-order term, i.e., one-order higher than the gradient approximation. After constructing self-energy resummed propagator, we formulated two kinds of mutually equivalent perturbative frameworks: The first one is formulated on the basis of the ``bare'' number density function, and the second one is formulated on the basis of ``physical'' number density function. In the course of construction of the second framework, the generalized Boltzmann equations directly come out, which describe the evolution of the system.

Analytical Study on the Saturated Polarization Under Electric Field and Phase Equilibrium of Three-Phase Polycrystalline Ferroelectrics by Using the Generalized Inverse-Pole-Figure Model

NASA Astrophysics Data System (ADS)

Ju, Kyong-Sik; Ryo, Hyok-Su; Pak, Sung-Nam; Pak, Chang-Su; Ri, Sung-Guk; Ri, Dok-Hwan

2018-07-01

By using the generalized inverse-pole-figure model, the numbers of crystalline particles involved in different domain-switching near the triple tetragonal-rhombohedral-orthorhombic (T-R-O) points of three-phase polycrystalline ferroelectrics have been analytically calculated and domain-switching which can bring out phase transformations has been considered. Through polarization by an electric field, different numbers of crystalline particles can be involved in different phase transformations. According to the phase equilibrium conditions, the phase equilibrium compositions of the three phases coexisting near the T-R-O triple point have been evaluated from the results of the numbers of crystalline particles involved in different phase transformations.

Stock markets as Minority Games: cognitive heterogeneity and equilibrium emergence

NASA Astrophysics Data System (ADS)

Brandouy, O.

2005-04-01

Standard finance theory generally assumes homogeneous agents relatively to their preferences, heuristics and investment strategies. We propose to study, in an agent-based simulation, the emergence of equilibrium under various heterogeneous conditions. Market interaction is stylized with the Minority Game representation. It is shown that inductive rational equilibrium emerges even though agents do not share the same representations of the value. This may lead to consider again the roots of EMH and REH.

Unique equilibrium states for Bonatti–Viana diffeomorphisms

NASA Astrophysics Data System (ADS)

Climenhaga, Vaughn; Fisher, Todd; Thompson, Daniel J.

2018-06-01

We show that the robustly transitive diffeomorphisms constructed by Bonatti and Viana have unique equilibrium states for natural classes of potentials. In particular, we characterize the SRB measure as the unique equilibrium state for a suitable geometric potential. The techniques developed are applicable to a wide class of DA diffeomorphisms, and persist under C 1 perturbations of the map. These results are an application of general machinery developed by the first and last named authors.

Equilibrium distribution of heavy quarks in fokker-planck dynamics

PubMed

Walton; Rafelski

2000-01-03

We obtain an explicit generalization, within Fokker-Planck dynamics, of Einstein's relation between drag, diffusion, and the equilibrium distribution for a spatially homogeneous system, considering both the transverse and longitudinal diffusion for dimension n>1. We provide a complete characterization of the equilibrium distribution in terms of the drag and diffusion transport coefficients. We apply this analysis to charm quark dynamics in a thermal quark-gluon plasma for the case of collisional equilibration.

Computations of ideal and real gas high altitude plume flows

NASA Technical Reports Server (NTRS)

Feiereisen, William J.; Venkatapathy, Ethiraj

1988-01-01

In the present work, complete flow fields around generic space vehicles in supersonic and hypersonic flight regimes are studied numerically. Numerical simulation is performed with a flux-split, time asymptotic viscous flow solver that incorporates a generalized equilibrium chemistry model. Solutions to generic problems at various altitude and flight conditions show the complexity of the flow, the equilibrium chemical dissociation and its effect on the overall flow field. Viscous ideal gas solutions are compared against equilibrium gas solutions to illustrate the effect of equilibrium chemistry. Improved solution accuracy is achieved through adaptive grid refinement.

Economics of nuclear power and climate change mitigation policies.

PubMed

Bauer, Nico; Brecha, Robert J; Luderer, Gunnar

2012-10-16

The events of March 2011 at the nuclear power complex in Fukushima, Japan, raised questions about the safe operation of nuclear power plants, with early retirement of existing nuclear power plants being debated in the policy arena and considered by regulators. Also, the future of building new nuclear power plants is highly uncertain. Should nuclear power policies become more restrictive, one potential option for climate change mitigation will be less available. However, a systematic analysis of nuclear power policies, including early retirement, has been missing in the climate change mitigation literature. We apply an energy economy model framework to derive scenarios and analyze the interactions and tradeoffs between these two policy fields. Our results indicate that early retirement of nuclear power plants leads to discounted cumulative global GDP losses of 0.07% by 2020. If, in addition, new nuclear investments are excluded, total losses will double. The effect of climate policies imposed by an intertemporal carbon budget on incremental costs of policies restricting nuclear power use is small. However, climate policies have much larger impacts than policies restricting the use of nuclear power. The carbon budget leads to cumulative discounted near term reductions of global GDP of 0.64% until 2020. Intertemporal flexibility of the carbon budget approach enables higher near-term emissions as a result of increased power generation from natural gas to fill the emerging gap in electricity supply, while still remaining within the overall carbon budget. Demand reductions and efficiency improvements are the second major response strategy.

Economics of nuclear power and climate change mitigation policies

PubMed Central

Bauer, Nico; Brecha, Robert J.; Luderer, Gunnar

2012-01-01

The events of March 2011 at the nuclear power complex in Fukushima, Japan, raised questions about the safe operation of nuclear power plants, with early retirement of existing nuclear power plants being debated in the policy arena and considered by regulators. Also, the future of building new nuclear power plants is highly uncertain. Should nuclear power policies become more restrictive, one potential option for climate change mitigation will be less available. However, a systematic analysis of nuclear power policies, including early retirement, has been missing in the climate change mitigation literature. We apply an energy economy model framework to derive scenarios and analyze the interactions and tradeoffs between these two policy fields. Our results indicate that early retirement of nuclear power plants leads to discounted cumulative global GDP losses of 0.07% by 2020. If, in addition, new nuclear investments are excluded, total losses will double. The effect of climate policies imposed by an intertemporal carbon budget on incremental costs of policies restricting nuclear power use is small. However, climate policies have much larger impacts than policies restricting the use of nuclear power. The carbon budget leads to cumulative discounted near term reductions of global GDP of 0.64% until 2020. Intertemporal flexibility of the carbon budget approach enables higher near-term emissions as a result of increased power generation from natural gas to fill the emerging gap in electricity supply, while still remaining within the overall carbon budget. Demand reductions and efficiency improvements are the second major response strategy. PMID:23027963

Patient and impatient punishers of free-riders

PubMed Central

Espín, Antonio M.; Brañas-Garza, Pablo; Herrmann, Benedikt; Gamella, Juan F.

2012-01-01

Costly punishment of cheaters who contribute little or nothing to a cooperating group has been extensively studied, as an effective means to enforce cooperation. The prevailing view is that individuals use punishment to retaliate against transgressions of moral standards such as fairness or equity. However, there is much debate regarding the psychological underpinnings of costly punishment. Some authors suggest that costly punishment must be a product of humans' capacity for reasoning, self-control and long-term planning, whereas others argue that it is the result of an impulsive, present-oriented emotional drive. Here, we explore the inter-temporal preferences of punishers in a multilateral cooperation game and show that both interpretations might be right, as we can identify two different types of punishment: punishment of free-riders by cooperators, which is predicted by patience (future orientation); and free-riders' punishment of other free-riders, which is predicted by impatience (present orientation). Therefore, the picture is more complex as punishment by free-riders probably comes not from a reaction against a moral transgression, but instead from a competitive, spiteful drive. Thus, punishment grounded on morals may be related to lasting or delayed psychological incentives, whereas punishment triggered by competitive desires may be linked to short-run aspirations. These results indicate that the individual's time horizon is relevant for the type of social behaviour she opts for. Integrating such differences in inter-temporal preferences and the social behaviour of agents might help to achieve a better understanding of how human cooperation and punishment behaviour has evolved. PMID:23075842

Living in the moment: Effects of time perspective and emotional valence of episodic thinking on delay discounting

PubMed Central

Lin, Henry; Epstein, Leonard H.

2014-01-01

Excessive delay discounting (DD) has been related to various maladaptive behaviors, and may stem from a myopic focus on immediate gratification. Neuroimaging studies have shown that episodic future thinking (EFT) – vivid mental simulation of future experiences – may reduce DD by promoting consideration of delayed outcomes. However, the EFT manipulations in these experiments may have induced positive affect, which could independently enhance executive functions that facilitate self-regulation. To clarify the mechanism of this effect, 87 participants were randomized to visualize neutral- or positive-valenced events expected to occur in the present or in the future while completing a standardized DD questionnaire. Working memory capacity, inhibitory control, the genotypes of 3 functional dopaminergic polymorphisms (DRD1 rs686, DRD2 rs1800497 and COMT rs4680), as well as an additive dopamine genetic risk score were assessed as potential moderators. The results indicate that EFT reduces DD primarily by shifting the time perspective of intertemporal decision-making, and that this effect is moderated by working memory capacity. In addition, positive episodic thinking may independently attenuate the protective effects of high working memory capacity, high inhibitory control, and lower dopamine genetic risk scores on DD. The current findings dovetail with previous research to suggest that the time perspective and emotional valence of episodic thinking may dynamically shape intertemporal choice, perhaps in part by transiently modulating executive function and dopaminergic neurotransmission. PMID:24512061

Patient and impatient punishers of free-riders.

PubMed

Espín, Antonio M; Brañas-Garza, Pablo; Herrmann, Benedikt; Gamella, Juan F

2012-12-22

Costly punishment of cheaters who contribute little or nothing to a cooperating group has been extensively studied, as an effective means to enforce cooperation. The prevailing view is that individuals use punishment to retaliate against transgressions of moral standards such as fairness or equity. However, there is much debate regarding the psychological underpinnings of costly punishment. Some authors suggest that costly punishment must be a product of humans' capacity for reasoning, self-control and long-term planning, whereas others argue that it is the result of an impulsive, present-oriented emotional drive. Here, we explore the inter-temporal preferences of punishers in a multilateral cooperation game and show that both interpretations might be right, as we can identify two different types of punishment: punishment of free-riders by cooperators, which is predicted by patience (future orientation); and free-riders' punishment of other free-riders, which is predicted by impatience (present orientation). Therefore, the picture is more complex as punishment by free-riders probably comes not from a reaction against a moral transgression, but instead from a competitive, spiteful drive. Thus, punishment grounded on morals may be related to lasting or delayed psychological incentives, whereas punishment triggered by competitive desires may be linked to short-run aspirations. These results indicate that the individual's time horizon is relevant for the type of social behaviour she opts for. Integrating such differences in inter-temporal preferences and the social behaviour of agents might help to achieve a better understanding of how human cooperation and punishment behaviour has evolved.

Turning Passive Brownian Motion Into Active Motion

NASA Astrophysics Data System (ADS)

Sevilla, Francisco J.; VáSquez-Arzola, Alejandro; Puga-Cital, Enrique

We consider out-of-equilibrium phenomena, specifically, the pattern of motion of active particles. These particles absorb energy from the environment and transform it into self-locomotion, generally, through complex mechanisms. Though the out-of-equilibrium nature of on the motion of these systems is well recognized, is generally difficult to pinpoint how far from equilibrium these systems are. In this work we elucidate the out-of-equilibrium nature of non-interacting, trapped, active particles, whose pattern of motion is described by a run-and-tumble dynamics. We show that the stationary distributions of these run-and-tumble particles, moving under the effects of an external potential, is equivalent to the stationary distribution of non-interacting, passive Brownian particles moving in the same potential but in an inhomogeneous source of heat. The interest in this topic has recently regrown due to the experimental possibility to design man-made active particles that emulate the ones that exist in the biological realm. F.J.S kindly acknowledges support from Grant UNAM-DGAPA-PAPIIT-IN113114.

Non-Equilibrium Properties from Equilibrium Free Energy Calculations

NASA Technical Reports Server (NTRS)

Pohorille, Andrew; Wilson, Michael A.

2012-01-01

Calculating free energy in computer simulations is of central importance in statistical mechanics of condensed media and its applications to chemistry and biology not only because it is the most comprehensive and informative quantity that characterizes the eqUilibrium state, but also because it often provides an efficient route to access dynamic and kinetic properties of a system. Most of applications of equilibrium free energy calculations to non-equilibrium processes rely on a description in which a molecule or an ion diffuses in the potential of mean force. In general case this description is a simplification, but it might be satisfactorily accurate in many instances of practical interest. This hypothesis has been tested in the example of the electrodiffusion equation . Conductance of model ion channels has been calculated directly through counting the number of ion crossing events observed during long molecular dynamics simulations and has been compared with the conductance obtained from solving the generalized Nernst-Plank equation. It has been shown that under relatively modest conditions the agreement between these two approaches is excellent, thus demonstrating the assumptions underlying the diffusion equation are fulfilled. Under these conditions the electrodiffusion equation provides an efficient approach to calculating the full voltage-current dependence routinely measured in electrophysiological experiments.

Some properties of correlations of quantum lattice systems in thermal equilibrium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fröhlich, Jürg, E-mail: juerg@phys.ethz.ch; Ueltschi, Daniel, E-mail: daniel@ueltschi.org

Simple proofs of uniqueness of the thermodynamic limit of KMS states and of the decay of equilibrium correlations are presented for a large class of quantum lattice systems at high temperatures. New quantum correlation inequalities for general Heisenberg models are described. Finally, a simplified derivation of a general result on power-law decay of correlations in 2D quantum lattice systems with continuous symmetries is given, extending results of McBryan and Spencer for the 2D classical XY model.

Rotating charged black holes accelerated by an electric field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bicak, Jiri; Kofron, David; Max Planck Institute for Gravitational Physics, Albert Einstein Institute, Am Muehlenberg 1, D-14476 Golm

The Ernst method of removing nodal singularities from the charged C-metric representing a uniformly accelerated black hole with mass m, charge q and acceleration A by 'adding' an electric field E is generalized. Utilizing the new form of the C-metric found recently, Ernst's simple 'equilibrium condition' mA=qE valid for small accelerations is generalized for arbitrary A. The nodal singularity is removed also in the case of accelerating and rotating charged black holes, and the corresponding equilibrium condition is determined.

GENERIC Integrators: Structure Preserving Time Integration for Thermodynamic Systems

NASA Astrophysics Data System (ADS)

Öttinger, Hans Christian

2018-04-01

Thermodynamically admissible evolution equations for non-equilibrium systems are known to possess a distinct mathematical structure. Within the GENERIC (general equation for the non-equilibrium reversible-irreversible coupling) framework of non-equilibrium thermodynamics, which is based on continuous time evolution, we investigate the possibility of preserving all the structural elements in time-discretized equations. Our approach, which follows Moser's [1] construction of symplectic integrators for Hamiltonian systems, is illustrated for the damped harmonic oscillator. Alternative approaches are sketched.

Energy shift and Casimir-Polder force for an atom out of thermal equilibrium near a dielectric substrate

NASA Astrophysics Data System (ADS)

Zhou, Wenting; Yu, Hongwei

2014-09-01

We study the energy shift and the Casimir-Polder force of an atom out of thermal equilibrium near the surface of a dielectric substrate. We first generalize, adopting the local source hypothesis, the formalism proposed by Dalibard, Dupont-Roc, and Cohen-Tannoudji [J. Phys. (Paris) 43, 1617 (1982), 10.1051/jphys:0198200430110161700; J. Phys. (Paris) 45, 637 (1984), 10.1051/jphys:01984004504063700], which separates the contributions of thermal fluctuations and radiation reaction to the energy shift and allows a distinct treatment of atoms in the ground and excited states, to the case out of thermal equilibrium, and then we use the generalized formalism to calculate the energy shift and the Casimir-Polder force of an isotropically polarizable neutral atom. We identify the effects of the thermal fluctuations that originate from the substrate and the environment and discuss in detail how the Casimir-Polder force out of thermal equilibrium behaves in three different distance regions in both the low-temperature limit and the high-temperature limit for both the ground-state and excited-state atoms, with special attention devoted to the distinctive features as opposed to thermal equilibrium. In particular, we recover the distinctive behavior of the atom-wall force out of thermal equilibrium at large distances in the low-temperature limit recently found in a different theoretical framework, and furthermore we give a concrete region where this behavior holds.

Equilibrium Solutions of the Logarithmic Hamiltonian Leapfrog for the N-body Problem

NASA Astrophysics Data System (ADS)

Minesaki, Yukitaka

2018-04-01

We prove that a second-order logarithmic Hamiltonian leapfrog for the classical general N-body problem (CGNBP) designed by Mikkola and Tanikawa and some higher-order logarithmic Hamiltonian methods based on symmetric multicompositions of the logarithmic algorithm exactly reproduce the orbits of elliptic relative equilibrium solutions in the original CGNBP. These methods are explicit symplectic methods. Before this proof, only some implicit discrete-time CGNBPs proposed by Minesaki had been analytically shown to trace the orbits of elliptic relative equilibrium solutions. The proof is therefore the first existence proof for explicit symplectic methods. Such logarithmic Hamiltonian methods with a variable time step can also precisely retain periodic orbits in the classical general three-body problem, which generic numerical methods with a constant time step cannot do.

Global asymptotic stability to a generalized Cohen-Grossberg BAM neural networks of neutral type delays.

PubMed

Zhang, Zhengqiu; Liu, Wenbin; Zhou, Dongming

2012-01-01

In this paper, we first discuss the existence of a unique equilibrium point of a generalized Cohen-Grossberg BAM neural networks of neutral type delays by means of the Homeomorphism theory and inequality technique. Then, by applying the existence result of an equilibrium point and constructing a Lyapunov functional, we study the global asymptotic stability of the equilibrium solution to the above Cohen-Grossberg BAM neural networks of neutral type. In our results, the hypothesis for boundedness in the existing paper, which discussed Cohen-Grossberg neural networks of neutral type on the activation functions, are removed. Finally, we give an example to demonstrate the validity of our global asymptotic stability result for the above neural networks. Copyright © 2011 Elsevier Ltd. All rights reserved.

Characterization of Weak Convergence of Probability-Valued Solutions of General One-Dimensional Kinetic Equations

NASA Astrophysics Data System (ADS)

Perversi, Eleonora; Regazzini, Eugenio

2015-05-01

For a general inelastic Kac-like equation recently proposed, this paper studies the long-time behaviour of its probability-valued solution. In particular, the paper provides necessary and sufficient conditions for the initial datum in order that the corresponding solution converges to equilibrium. The proofs rest on the general CLT for independent summands applied to a suitable Skorokhod representation of the original solution evaluated at an increasing and divergent sequence of times. It turns out that, roughly speaking, the initial datum must belong to the standard domain of attraction of a stable law, while the equilibrium is presentable as a mixture of stable laws.

The geometry of structural equilibrium

PubMed Central

2017-01-01

Building on a long tradition from Maxwell, Rankine, Klein and others, this paper puts forward a geometrical description of structural equilibrium which contains a procedure for the graphic analysis of stress resultants within general three-dimensional frames. The method is a natural generalization of Rankine’s reciprocal diagrams for three-dimensional trusses. The vertices and edges of dual abstract 4-polytopes are embedded within dual four-dimensional vector spaces, wherein the oriented area of generalized polygons give all six components (axial and shear forces with torsion and bending moments) of the stress resultants. The relevant quantities may be readily calculated using four-dimensional Clifford algebra. As well as giving access to frame analysis and design, the description resolves a number of long-standing problems with the incompleteness of Rankine’s description of three-dimensional trusses. Examples are given of how the procedure may be applied to structures of engineering interest, including an outline of a two-stage procedure for addressing the equilibrium of loaded gridshell rooves. PMID:28405361

Closed set of the uniqueness conditions and bifurcation criteria in generalized coupled thermoplasticity for small deformations

NASA Astrophysics Data System (ADS)

Śloderbach, Zdzisław

2016-05-01

This paper reports the results of a study into global and local conditions of uniqueness and the criteria excluding the possibility of bifurcation of the equilibrium state for small strains. The conditions and criteria are derived on the basis of an analysis of the problem of uniqueness of a solution involving the basic incremental boundary problem of coupled generalized thermo-elasto-plasticity. This work forms a follow-up of previous research (Śloderbach in Bifurcations criteria for equilibrium states in generalized thermoplasticity, IFTR Reports, 1980, Arch Mech 3(35):337-349, 351-367, 1983), but contains a new derivation of global and local criteria excluding a possibility of bifurcation of an equilibrium state regarding a comparison body dependent on the admissible fields of stress rate. The thermal elasto-plastic coupling effects, non-associated laws of plastic flow and influence of plastic strains on thermoplastic properties of a body were taken into account in this work. Thus, the mathematical problem considered here is not a self-conjugated problem.

Model-based analysis of coupled equilibrium-kinetic processes: indirect kinetic studies of thermodynamic parameters using the dynamic data.

PubMed

Emami, Fereshteh; Maeder, Marcel; Abdollahi, Hamid

2015-05-07

Thermodynamic studies of equilibrium chemical reactions linked with kinetic procedures are mostly impossible by traditional approaches. In this work, the new concept of generalized kinetic study of thermodynamic parameters is introduced for dynamic data. The examples of equilibria intertwined with kinetic chemical mechanisms include molecular charge transfer complex formation reactions, pH-dependent degradation of chemical compounds and tautomerization kinetics in micellar solutions. Model-based global analysis with the possibility of calculating and embedding the equilibrium and kinetic parameters into the fitting algorithm has allowed the complete analysis of the complex reaction mechanisms. After the fitting process, the optimal equilibrium and kinetic parameters together with an estimate of their standard deviations have been obtained. This work opens up a promising new avenue for obtaining equilibrium constants through the kinetic data analysis for the kinetic reactions that involve equilibrium processes.

Progress Toward an Efficient and General CFD Tool for Propulsion Design/Analysis

NASA Technical Reports Server (NTRS)

Cox, C. F.; Cinnella, P.; Westmoreland, S.

1996-01-01

The simulation of propulsive flows inherently involves chemical activity. Recent years have seen substantial strides made in the development of numerical schemes for reacting flowfields, in particular those involving finite-rate chemistry. However, finite-rate calculations are computationally intensive and require knowledge of the actual kinetics, which are not always known with sufficient accuracy. Alternatively, flow simulations based on the assumption of local chemical equilibrium are capable of obtaining physically reasonable results at far less computational cost. The present study summarizes the development of efficient numerical techniques for the simulation of flows in local chemical equilibrium, whereby a 'Black Box' chemical equilibrium solver is coupled to the usual gasdynamic equations. The generalization of the methods enables the modelling of any arbitrary mixture of thermally perfect gases, including air, combustion mixtures and plasmas. As demonstration of the potential of the methodologies, several solutions, involving reacting and perfect gas flows, will be presented. Included is a preliminary simulation of the SSME startup transient. Future enhancements to the proposed techniques will be discussed, including more efficient finite-rate and hybrid (partial equilibrium) schemes. The algorithms that have been developed and are being optimized provide for an efficient and general tool for the design and analysis of propulsion systems.

Resonant behaviour of MHD waves on magnetic flux tubes. III - Effect of equilibrium flow

NASA Technical Reports Server (NTRS)

Goossens, Marcel; Hollweg, Joseph V.; Sakurai, Takashi

1992-01-01

The Hollweg et al. (1990) analysis of MHD surface waves in a stationary equilibrium is extended. The conservation laws and jump conditions at Alfven and slow resonance points obtained by Sakurai et al. (1990) are generalized to include an equilibrium flow, and the assumption that the Eulerian perturbation of total pressure is constant is recovered as the special case of the conservation law for an equilibrium with straight magnetic field lines and flow along the magnetic field lines. It is shown that the conclusions formulated by Hollweg et al. are still valid for the straight cylindrical case. The effect of curvature is examined.

Relations between dissipated work and Rényi divergences in the generalized Gibbs ensemble

NASA Astrophysics Data System (ADS)

Wei, Bo-Bo

2018-04-01

In this work, we show that the dissipation in a many-body system under an arbitrary nonequilibrium process is related to the Rényi divergences between two states along the forward and reversed dynamics under a very general family of initial conditions. This relation generalizes the links between dissipated work and Rényi divergences to quantum systems with conserved quantities whose equilibrium state is described by the generalized Gibbs ensemble. The relation is applicable for quantum systems with conserved quantities and can be applied to protocols driving the system between integrable and chaotic regimes. We demonstrate our ideas by considering the one-dimensional transverse quantum Ising model and the Jaynes-Cummings model which are driven out of equilibrium.

Teaching Chemical Equilibrium with the Jigsaw Technique

ERIC Educational Resources Information Center

Doymus, Kemal

2008-01-01

This study investigates the effect of cooperative learning (jigsaw) versus individual learning methods on students' understanding of chemical equilibrium in a first-year general chemistry course. This study was carried out in two different classes in the department of primary science education during the 2005-2006 academic year. One of the classes…

Understanding Thermal Equilibrium through Activities

ERIC Educational Resources Information Center

Pathare, Shirish; Huli, Saurabhee; Nachane, Madhura; Ladage, Savita; Pradhan, Hemachandra

2015-01-01

Thermal equilibrium is a basic concept in thermodynamics. In India, this concept is generally introduced at the first year of undergraduate education in physics and chemistry. In our earlier studies (Pathare and Pradhan 2011 "Proc. episteme-4 Int. Conf. to Review Research on Science Technology and Mathematics Education" pp 169-72) we…

Strategies Reported Used by Instructors to Address Student Alternate Conceptions in Chemical Equilibrium

ERIC Educational Resources Information Center

Piquette, Jeff S.; Heikkinen, Henry W.

2005-01-01

This study explores general-chemistry instructors' awareness of and ability to identify and address common student learning obstacles in chemical equilibrium. Reported instructor strategies directed at remediating student alternate conceptions were investigated and compared with successful, literature-based conceptual change methods. Fifty-two…

Education Policy and Intergenerational Transfers in Equilibrium. NBER Working Paper No. 18782

ERIC Educational Resources Information Center

Abbott, Brant; Gallipoli, Giovanni; Meghir, Costas; Violante, Giovanni L.

2013-01-01

This paper compares partial and general equilibrium effects of alternative financial aid policies intended to promote college participation. We build an overlapping generations life-cycle, heterogeneous-agent, incomplete-markets model with education, labor supply, and consumption/saving decisions. Altruistic parents make inter vivos transfers to…

Bright solitons in non-equilibrium coherent quantum matter

PubMed Central

Pinsker, F.; Flayac, H.

2016-01-01

We theoretically demonstrate a mechanism for bright soliton generation in spinor non-equilibrium Bose–Einstein condensates made of atoms or quasi-particles such as polaritons in semiconductor microcavities. We give analytical expressions for bright (half) solitons as minimizing functions of a generalized non-conservative Lagrangian elucidating the unique features of inter and intra-competition in non-equilibrium systems. The analytical results are supported by a detailed numerical analysis that further shows the rich soliton dynamics inferred by their instability and mutual cross-interactions. PMID:26997892

Computing Properties Of Chemical Mixtures At Equilibrium

NASA Technical Reports Server (NTRS)

Mcbride, B. J.; Gordon, S.

1995-01-01

Scientists and engineers need data on chemical equilibrium compositions to calculate theoretical thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93 is general program that calculates chemical equilibrium compositions and properties of mixtures for any chemical system for which thermodynamic data are available. Includes thermodynamic data for more than 1,300 gaseous and condensed species and thermal-transport data for 151 gases. Written in FORTRAN 77.

Integral Equation for the Equilibrium State of Colliding Electron Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warnock, Robert L.

2002-11-11

We study a nonlinear integral equation for the equilibrium phase distribution of stored colliding electron beams. It is analogous to the Haissinski equation, being derived from Vlasov-Fokker-Planck theory, but is quite different in form. We prove existence of a unique solution, thus the existence of a unique equilibrium state, for sufficiently small current. This is done for the Chao-Ruth model of the beam-beam interaction in one degree of freedom. We expect no difficulty in generalizing the argument to more realistic models.

One-dimensional Vlasov-Maxwell equilibrium for the force-free Harris sheet.

PubMed

Harrison, Michael G; Neukirch, Thomas

2009-04-03

In this Letter, the first nonlinear force-free Vlasov-Maxwell equilibrium is presented. One component of the equilibrium magnetic field has the same spatial structure as the Harris sheet, but whereas the Harris sheet is kept in force balance by pressure gradients, in the force-free solution presented here force balance is maintained by magnetic shear. Magnetic pressure, plasma pressure and plasma density are constant. The method used to find the equilibrium is based on the analogy of the one-dimensional Vlasov-Maxwell equilibrium problem to the motion of a pseudoparticle in a two-dimensional conservative potential. The force-free solution can be generalized to a complete family of equilibria that describe the transition between the purely pressure-balanced Harris sheet to the force-free Harris sheet.

Intermittent many-body dynamics at equilibrium

NASA Astrophysics Data System (ADS)

Danieli, C.; Campbell, D. K.; Flach, S.

2017-06-01

The equilibrium value of an observable defines a manifold in the phase space of an ergodic and equipartitioned many-body system. A typical trajectory pierces that manifold infinitely often as time goes to infinity. We use these piercings to measure both the relaxation time of the lowest frequency eigenmode of the Fermi-Pasta-Ulam chain, as well as the fluctuations of the subsequent dynamics in equilibrium. The dynamics in equilibrium is characterized by a power-law distribution of excursion times far off equilibrium, with diverging variance. Long excursions arise from sticky dynamics close to q -breathers localized in normal mode space. Measuring the exponent allows one to predict the transition into nonergodic dynamics. We generalize our method to Klein-Gordon lattices where the sticky dynamics is due to discrete breathers localized in real space.

ON THE DYNAMICAL DERIVATION OF EQUILIBRIUM STATISTICAL MECHANICS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prigogine, I.; Balescu, R.; Henin, F.

1960-12-01

Work on nonequilibrium statistical mechanics, which allows an extension of the kinetic proof to all results of equilibrium statistical mechanics involving a finite number of degrees of freedom, is summarized. As an introduction to the general N-body problem, the scattering theory in classical mechanics is considered. The general N-body problem is considered for the case of classical mechanics, quantum mechanics with Boltzmann statistics, and quantum mechanics including quantum statistics. Six basic diagrams, which describe the elementary processes of the dynamics of correlations, were obtained. (M.C.G.)

A Class of Solvable Stopping Games

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alvarez, Luis H. R.

We consider a class of Dynkin games in the case where the underlying process evolves according to a one-dimensional but otherwise general diffusion. We establish general conditions under which both the value and the saddle point equilibrium exist and under which the exercise boundaries characterizing the saddle point strategy can be explicitly characterized in terms of a pair of standard first order necessary conditions for optimality. We also analyze those cases where an extremal pair of boundaries exists and investigate the overall impact of increased volatility on the equilibrium stopping strategies and their values.

Entropic Description of Gas Hydrate Ice-Liquid Equilibrium via Enhanced Sampling of Coexisting Phases

NASA Astrophysics Data System (ADS)

Małolepsza, Edyta; Kim, Jaegil; Keyes, Tom

2015-05-01

Metastable β ice holds small guest molecules in stable gas hydrates, so its solid-liquid equilibrium is of interest. However, aqueous crystal-liquid transitions are very difficult to simulate. A new molecular dynamics algorithm generates trajectories in a generalized N P T ensemble and equilibrates states of coexisting phases with a selectable enthalpy. With replicas spanning the range between β ice and liquid water, we find the statistical temperature from the enthalpy histograms and characterize the transition by the entropy, introducing a general computational procedure for first-order transitions.

Geometric approach to nuclear pasta phases

NASA Astrophysics Data System (ADS)

Kubis, Sebastian; Wójcik, Włodzimierz

2016-12-01

By use of the variational methods and differential geometry in the framework of the liquid drop model we formulate appropriate equilibrium equations for pasta phases with imposed periodicity. The extension of the Young-Laplace equation in the case of charged fluid is obtained. The β equilibrium and virial theorem are also generalized. All equations are shown in gauge invariant form. For the first time, the pasta shape stability analysis is carried out. The proper stability condition in the form of the generalized Jacobi equation is derived. The presented formalism is tested on some particular cases.

Entropic description of gas hydrate ice/liquid equilibrium via enhanced sampling of coexisting phases

DOE PAGES

Malolepsza, Edyta; Kim, Jaegil; Keyes, Tom

2015-04-28

Metastable β ice holds small guest molecules in stable gas hydrates, so its solid/liquid equilibrium is of interest. However, aqueous crystal/liquid transitions are very difficult to simulate. A new MD algorithm generates trajectories in a generalized NPT ensemble and equilibrates states of coexisting phases with a selectable enthalpy. Furthermore, with replicas spanning the range between β ice and liquid water we find the statistical temperature from the enthalpy histograms and characterize the transition by the entropy, introducing a general computational procedure for first-order transitions.

IONIZATION EQUILIBRIUM TIMESCALES IN COLLISIONAL PLASMAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Randall K.; Hughes, John P., E-mail: rsmith@cfa.harvard.ed, E-mail: jph@physics.rutgers.ed

2010-07-20

Astrophysical shocks or bursts from a photoionizing source can disturb the typical collisional plasma found in galactic interstellar media or the intergalactic medium. The spectrum emitted by this plasma contains diagnostics that have been used to determine the time since the disturbing event, although this determination becomes uncertain as the elements in the plasma return to ionization equilibrium. A general solution for the equilibrium timescale for each element arises from the elegant eigenvector method of solution to the problem of a non-equilibrium plasma described by Masai and Hughes and Helfand. In general, the ionization evolution of an element Z inmore » a constant electron temperature plasma is given by a coupled set of Z + 1 first-order differential equations. However, they can be recast as Z uncoupled first-order differential equations using an eigenvector basis for the system. The solution is then Z separate exponential functions, with the time constants given by the eigenvalues of the rate matrix. The smallest of these eigenvalues gives the scale of the slowest return to equilibrium independent of the initial conditions, while conversely the largest eigenvalue is the scale of the fastest change in the ion population. These results hold for an ionizing plasma, a recombining plasma, or even a plasma with random initial conditions, and will allow users of these diagnostics to determine directly if their best-fit result significantly limits the timescale since a disturbance or is so close to equilibrium as to include an arbitrarily long time.« less

On the LHC sensitivity for non-thermalised hidden sectors

NASA Astrophysics Data System (ADS)

Kahlhoefer, Felix

2018-04-01

We show under rather general assumptions that hidden sectors that never reach thermal equilibrium in the early Universe are also inaccessible for the LHC. In other words, any particle that can be produced at the LHC must either have been in thermal equilibrium with the Standard Model at some point or must be produced via the decays of another hidden sector particle that has been in thermal equilibrium. To reach this conclusion, we parametrise the cross section connecting the Standard Model to the hidden sector in a very general way and use methods from linear programming to calculate the largest possible number of LHC events compatible with the requirement of non-thermalisation. We find that even the HL-LHC cannot possibly produce more than a few events with energy above 10 GeV involving states from a non-thermalised hidden sector.

Connecting Solubility, Equilibrium, and Periodicity in a Green, Inquiry Experiment for the General Chemistry Laboratory

ERIC Educational Resources Information Center

Cacciatore, Kristen L.; Amado, Jose; Evans, Jason J.; Sevian, Hannah

2008-01-01

We present a novel first-year chemistry laboratory experiment that connects solubility, equilibrium, and chemical periodicity concepts. It employs a unique format that asks students to replicate experiments described in different sample lab reports, each lacking some essential information, rather than follow a scripted procedure. This structure is…

Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Procedures for the Determination of the Freely Dissolved Interstitial Water Concentrations of Nonionic Organics

EPA Science Inventory

This document describes procedures to determine the concentrations of nonionic organic chemicals in sediment interstitial waters. In previous ESB documents, the general equilibrium partitioning (EqP) approach was chosen for the derivation of sediment benchmarks because it account...

Systematic Approach to Calculate the Concentration of Chemical Species in Multi-Equilibrium Problems

ERIC Educational Resources Information Center

Baeza-Baeza, Juan Jose; Garcia-Alvarez-Coque, Maria Celia

2011-01-01

A general systematic approach is proposed for the numerical calculation of multi-equilibrium problems. The approach involves several steps: (i) the establishment of balances involving the chemical species in solution (e.g., mass balances, charge balance, and stoichiometric balance for the reaction products), (ii) the selection of the unknowns (the…

Using the Science Writing Heuristic to Improve Students' Understanding of General Equilibrium

ERIC Educational Resources Information Center

Rudd, James A., II; Greenbowe, Thomas J.; Hand, Brian M.

2007-01-01

This study compared the performance of students using the Science Writing Heuristic (SWH) approach and students using a standard or traditional laboratory curriculum on lecture exams and a laboratory practical exam on a specific topic, chemical equilibrium. The SWH helps students do inquiry science laboratory work by structuring the laboratory…

Exact results in nonequilibrium statistical mechanics: Formalism and applications in chemical kinetics and single-molecule free energy estimation

NASA Astrophysics Data System (ADS)

Adib, Artur B.

In the last two decades or so, a collection of results in nonequilibrium statistical mechanics that departs from the traditional near-equilibrium framework introduced by Lars Onsager in 1931 has been derived, yielding new fundamental insights into far-from-equilibrium processes in general. Apart from offering a more quantitative statement of the second law of thermodynamics, some of these results---typified by the so-called "Jarzynski equality"---have also offered novel means of estimating equilibrium quantities from nonequilibrium processes, such as free energy differences from single-molecule "pulling" experiments. This thesis contributes to such efforts by offering three novel results in nonequilibrium statistical mechanics: (a) The entropic analog of the Jarzynski equality; (b) A methodology for estimating free energies from "clamp-and-release" nonequilibrium processes; and (c) A directly measurable symmetry relation in chemical kinetics similar to (but more general than) chemical detailed balance. These results share in common the feature of remaining valid outside Onsager's near-equilibrium regime, and bear direct applicability in protein folding kinetics as well as in single-molecule free energy estimation.

Non-equilibrium quantum heat machines

NASA Astrophysics Data System (ADS)

Alicki, Robert; Gelbwaser-Klimovsky, David

2015-11-01

Standard heat machines (engine, heat pump, refrigerator) are composed of a system (working fluid) coupled to at least two equilibrium baths at different temperatures and periodically driven by an external device (piston or rotor) sometimes called the work reservoir. The aim of this paper is to go beyond this scheme by considering environments which are stationary but cannot be decomposed into a few baths at thermal equilibrium. Such situations are important, for example in solar cells, chemical machines in biology, various realizations of laser cooling or nanoscopic machines driven by laser radiation. We classify non-equilibrium baths depending on their thermodynamic behavior and show that the efficiency of heat machines powered by them is limited by the generalized Carnot bound.

Liapunov stability analysis of hybrid dynamical systems in the neighborhood of nontrivial equilibrium

NASA Technical Reports Server (NTRS)

Meirovitch, L.

1973-01-01

This paper is concerned with the stability of a hybrid dynamical system in the neighborhood of a nontrivial equilibrium, where the system consists of one rigid part and n elastic members. The body moves in a central-force field with its mass center describing a circular orbit. The nontrivial equilibrium is defined by steady rotation of the system at an angular velocity equal to the orbital velocity, with the elastic members being in deformed state. A Liapunov stability analysis is performed by assuming small perturbations about the nontrivial equilibrium, where the latter is generally defined by nonlinear differential equations. The theory is applied to a gravity-gradient stabilized satellite with flexible appendages.

A low tension between individual and societal time aspects in health improved outcomes.

PubMed

Ortendahl, Monica; Fries, James F

2006-11-01

To review intertemporal choices, involving decisions with a trade-off between something now and something later. These choices are common in health both at an individual and societal level. The present value of an outcome, for example, the amount of money or the health outcomes in various aspects, is equivalent to the value of a future outcome discounted with the delay of time. The concept of diminishing value over time is positive discounting. Economic forecasts generally use discount rates in which the value of a future dollar is less than the value of a present dollar, and where the discount rates are similar for the individual investor and society. The value of future health is commonly thought of as similar to the value of future money. Yet, the individual may rationally choose a discount rate that is exceedingly low or even negative. This paradox is particularly relevant when considering primary and secondary prevention, where initial and continuing costs may precede beneficent outcomes by decades, making discount rate selections the dominant factor in determining decisions. We suggest that the societal perspective should also recognize that discount rates for health outcomes are largely irrelevant and that even negative discount rates have crucial relevance.

Deficient neural activity subserving decision-making during reward waiting time in intertemporal choice in adult attention-deficit hyperactivity disorder.

PubMed

Todokoro, Ayako; Tanaka, Saori C; Kawakubo, Yuki; Yahata, Noriaki; Ishii-Takahashi, Ayaka; Nishimura, Yukika; Kano, Yukiko; Ohtake, Fumio; Kasai, Kiyoto

2018-04-24

Impulsivity, which significantly affects social adaptation, is an important target behavioral characteristic in interventions for attention-deficit hyperactivity disorder (ADHD). Typically, people are willing to wait longer to acquire greater rewards. Impulsivity in ADHD may be associated with brain dysfunction in decision-making involving waiting behavior under such situations. We tested the hypothesis that brain circuitry during a period of waiting (i.e., prior to the acquisition of reward) is altered in adults with ADHD. The participants included 14 medication-free adults with ADHD and 16 healthy controls matched for age, sex, IQ, and handedness. The behavioral task had participants choose between a delayed, larger monetary reward and an immediate, smaller monetary reward, where the reward waiting time actually occurred during functional magnetic resonance imaging measurement. We tested for group differences in the contrast values of blood-oxygen-level dependent signals associated with the length of waiting time, calculated using the parametric modulation method. While the two groups did not differ in the time discounting rate, the delay-sensitive contrast values were significantly lower in the caudate and visual cortex in individuals with ADHD. The higher impulsivity scores were significantly associated with lower delay-sensitive contrast values in the caudate and visual cortex. These results suggest that deficient neural activity affects decision-making involving reward waiting time during intertemporal choice tasks, and provide an explanation for the basis of impulsivity in adult ADHD. © 2018 The Author. Psychiatry and Clinical Neurosciences © 2018 Japanese Society of Psychiatry and Neurology.

Thermal conductance at the interface between crystals using equilibrium and nonequilibrium molecular dynamics

NASA Astrophysics Data System (ADS)

Merabia, Samy; Termentzidis, Konstantinos

2012-09-01

In this article, we compare the results of nonequilibrium (NEMD) and equilibrium (EMD) molecular dynamics methods to compute the thermal conductance at the interface between solids. We propose to probe the thermal conductance using equilibrium simulations measuring the decay of the thermally induced energy fluctuations of each solid. We also show that NEMD and EMD give generally speaking inconsistent results for the thermal conductance: Green-Kubo simulations probe the Landauer conductance between two solids which assumes phonons on both sides of the interface to be at equilibrium. On the other hand, we show that NEMD give access to the out-of-equilibrium interfacial conductance consistent with the interfacial flux describing phonon transport in each solid. The difference may be large and reaches typically a factor 5 for interfaces between usual semiconductors. We analyze finite size effects for the two determinations of the interfacial thermal conductance, and show that the equilibrium simulations suffer from severe size effects as compared to NEMD. We also compare the predictions of the two above-mentioned methods—EMD and NEMD—regarding the interfacial conductance of a series of mass mismatched Lennard-Jones solids. We show that the Kapitza conductance obtained with EMD can be well described using the classical diffuse mismatch model (DMM). On the other hand, NEMD simulation results are consistent with an out-of-equilibrium generalization of the acoustic mismatch model (AMM). These considerations are important in rationalizing previous results obtained using molecular dynamics, and help in pinpointing the physical scattering mechanisms taking place at atomically perfect interfaces between solids, which is a prerequisite to understand interfacial heat transfer across real interfaces.

Stochastic thermodynamics of quantum maps with and without equilibrium.

PubMed

Barra, Felipe; Lledó, Cristóbal

2017-11-01

We study stochastic thermodynamics for a quantum system of interest whose dynamics is described by a completely positive trace-preserving (CPTP) map as a result of its interaction with a thermal bath. We define CPTP maps with equilibrium as CPTP maps with an invariant state such that the entropy production due to the action of the map on the invariant state vanishes. Thermal maps are a subgroup of CPTP maps with equilibrium. In general, for CPTP maps, the thermodynamic quantities, such as the entropy production or work performed on the system, depend on the combined state of the system plus its environment. We show that these quantities can be written in terms of system properties for maps with equilibrium. The relations that we obtain are valid for arbitrary coupling strengths between the system and the thermal bath. The fluctuations of thermodynamic quantities are considered in the framework of a two-point measurement scheme. We derive the entropy production fluctuation theorem for general maps and a fluctuation relation for the stochastic work on a system that starts in the Gibbs state. Some simplifications for the probability distributions in the case of maps with equilibrium are presented. We illustrate our results by considering spin 1/2 systems under thermal maps, nonthermal maps with equilibrium, maps with nonequilibrium steady states, and concatenations of them. Finally, and as an important application, we consider a particular limit in which the concatenation of maps generates a continuous time evolution in Lindblad form for the system of interest, and we show that the concept of maps with and without equilibrium translates into Lindblad equations with and without quantum detailed balance, respectively. The consequences for the thermodynamic quantities in this limit are discussed.

Stochastic thermodynamics of quantum maps with and without equilibrium

NASA Astrophysics Data System (ADS)

Barra, Felipe; Lledó, Cristóbal

2017-11-01

We study stochastic thermodynamics for a quantum system of interest whose dynamics is described by a completely positive trace-preserving (CPTP) map as a result of its interaction with a thermal bath. We define CPTP maps with equilibrium as CPTP maps with an invariant state such that the entropy production due to the action of the map on the invariant state vanishes. Thermal maps are a subgroup of CPTP maps with equilibrium. In general, for CPTP maps, the thermodynamic quantities, such as the entropy production or work performed on the system, depend on the combined state of the system plus its environment. We show that these quantities can be written in terms of system properties for maps with equilibrium. The relations that we obtain are valid for arbitrary coupling strengths between the system and the thermal bath. The fluctuations of thermodynamic quantities are considered in the framework of a two-point measurement scheme. We derive the entropy production fluctuation theorem for general maps and a fluctuation relation for the stochastic work on a system that starts in the Gibbs state. Some simplifications for the probability distributions in the case of maps with equilibrium are presented. We illustrate our results by considering spin 1/2 systems under thermal maps, nonthermal maps with equilibrium, maps with nonequilibrium steady states, and concatenations of them. Finally, and as an important application, we consider a particular limit in which the concatenation of maps generates a continuous time evolution in Lindblad form for the system of interest, and we show that the concept of maps with and without equilibrium translates into Lindblad equations with and without quantum detailed balance, respectively. The consequences for the thermodynamic quantities in this limit are discussed.

Modelling non-equilibrium thermodynamic systems from the speed-gradient principle.

PubMed

Khantuleva, Tatiana A; Shalymov, Dmitry S

2017-03-06

The application of the speed-gradient (SG) principle to the non-equilibrium distribution systems far away from thermodynamic equilibrium is investigated. The options for applying the SG principle to describe the non-equilibrium transport processes in real-world environments are discussed. Investigation of a non-equilibrium system's evolution at different scale levels via the SG principle allows for a fresh look at the thermodynamics problems associated with the behaviour of the system entropy. Generalized dynamic equations for finite and infinite number of constraints are proposed. It is shown that the stationary solution to the equations, resulting from the SG principle, entirely coincides with the locally equilibrium distribution function obtained by Zubarev. A new approach to describe time evolution of systems far from equilibrium is proposed based on application of the SG principle at the intermediate scale level of the system's internal structure. The problem of the high-rate shear flow of viscous fluid near the rigid plane plate is discussed. It is shown that the SG principle allows closed mathematical models of non-equilibrium processes to be constructed.This article is part of the themed issue 'Horizons of cybernetical physics'. © 2017 The Author(s).

Modelling non-equilibrium thermodynamic systems from the speed-gradient principle

NASA Astrophysics Data System (ADS)

Khantuleva, Tatiana A.; Shalymov, Dmitry S.

2017-03-01

The application of the speed-gradient (SG) principle to the non-equilibrium distribution systems far away from thermodynamic equilibrium is investigated. The options for applying the SG principle to describe the non-equilibrium transport processes in real-world environments are discussed. Investigation of a non-equilibrium system's evolution at different scale levels via the SG principle allows for a fresh look at the thermodynamics problems associated with the behaviour of the system entropy. Generalized dynamic equations for finite and infinite number of constraints are proposed. It is shown that the stationary solution to the equations, resulting from the SG principle, entirely coincides with the locally equilibrium distribution function obtained by Zubarev. A new approach to describe time evolution of systems far from equilibrium is proposed based on application of the SG principle at the intermediate scale level of the system's internal structure. The problem of the high-rate shear flow of viscous fluid near the rigid plane plate is discussed. It is shown that the SG principle allows closed mathematical models of non-equilibrium processes to be constructed. This article is part of the themed issue 'Horizons of cybernetical physics'.

Modelling non-equilibrium thermodynamic systems from the speed-gradient principle

PubMed Central

Khantuleva, Tatiana A.

2017-01-01

The application of the speed-gradient (SG) principle to the non-equilibrium distribution systems far away from thermodynamic equilibrium is investigated. The options for applying the SG principle to describe the non-equilibrium transport processes in real-world environments are discussed. Investigation of a non-equilibrium system's evolution at different scale levels via the SG principle allows for a fresh look at the thermodynamics problems associated with the behaviour of the system entropy. Generalized dynamic equations for finite and infinite number of constraints are proposed. It is shown that the stationary solution to the equations, resulting from the SG principle, entirely coincides with the locally equilibrium distribution function obtained by Zubarev. A new approach to describe time evolution of systems far from equilibrium is proposed based on application of the SG principle at the intermediate scale level of the system's internal structure. The problem of the high-rate shear flow of viscous fluid near the rigid plane plate is discussed. It is shown that the SG principle allows closed mathematical models of non-equilibrium processes to be constructed. This article is part of the themed issue ‘Horizons of cybernetical physics’. PMID:28115617

Under What Conditions Can Equilibrium Gas-Particle Partitioning Be Expected to Hold in the Atmosphere?

PubMed

Mai, Huajun; Shiraiwa, Manabu; Flagan, Richard C; Seinfeld, John H

2015-10-06

The prevailing treatment of secondary organic aerosol formation in atmospheric models is based on the assumption of instantaneous gas-particle equilibrium for the condensing species, yet compelling experimental evidence indicates that organic aerosols can exhibit the properties of highly viscous, semisolid particles, for which gas-particle equilibrium may be achieved slowly. The approach to gas-particle equilibrium partitioning is controlled by gas-phase diffusion, interfacial transport, and particle-phase diffusion. Here we evaluate the controlling processes and the time scale to achieve gas-particle equilibrium as a function of the volatility of the condensing species, its surface accommodation coefficient, and its particle-phase diffusivity. For particles in the size range of typical atmospheric organic aerosols (∼50-500 nm), the time scale to establish gas-particle equilibrium is generally governed either by interfacial accommodation or particle-phase diffusion. The rate of approach to equilibrium varies, depending on whether the bulk vapor concentration is constant, typical of an open system, or decreasing as a result of condensation into the particles, typical of a closed system.

Derivation of the chemical-equilibrium rate coefficient using scattering theory

NASA Technical Reports Server (NTRS)

Mickens, R. E.

1977-01-01

Scattering theory is applied to derive the equilibrium rate coefficient for a general homogeneous chemical reaction involving ideal gases. The reaction rate is expressed in terms of the product of a number of normalized momentum distribution functions, the product of the number of molecules with a given internal energy state, and the spin-averaged T-matrix elements. An expression for momentum distribution at equilibrium for an arbitrary molecule is presented, and the number of molecules with a given internal-energy state is represented by an expression which includes the partition function.

LeChâtelier's Principle in the Sciences

NASA Astrophysics Data System (ADS)

Thomsen, Volker B. E.

2000-02-01

LeChâtelier's principle of chemical equilibrium is actually a very general statement about systems in equilibrium and their behavior when subjected to external force or stress. Although one almost never finds mention of his name or law in other sciences, analogous principles and concepts do exist. In this note we examine some of the similar forms taken by this chemical principle in the fields of physics, geology, biology, and economics. Lenz's law in physics is an example of electromagnetic equilibrium and the geological principle of isostatic uplift concerns mechanical equilibrium. Both are strictly consequences of conservation of energy. LeChâtelier's principle deals with thermodynamic equilibrium and involves both the first and second laws of thermodynamics. The concept of homeostasis in biology and the economic law of supply and demand are both equilibrium-like principles, but involve systems in the steady state. However, all these principles involve the stability of the system under consideration and the analogies presented may be useful in the teaching of LeChâtelier's principle.

Heterogeneous nucleation in multi-component vapor on a partially wettable charged conducting particle. II. The generalized Laplace, Gibbs-Kelvin, and Young equations and application to nucleation.

PubMed

Noppel, M; Vehkamäki, H; Winkler, P M; Kulmala, M; Wagner, P E

2013-10-07

Based on the results of a previous paper [M. Noppel, H. Vehkamäki, P. M. Winkler, M. Kulmala, and P. E. Wagner, J. Chem. Phys. 139, 134107 (2013)], we derive a thermodynamically consistent expression for reversible or minimal work needed to form a dielectric liquid nucleus of a new phase on a charged insoluble conducting sphere within a uniform macroscopic one- or multicomponent mother phase. The currently available model for ion-induced nucleation assumes complete spherical symmetry of the system, implying that the seed ion is immediately surrounded by the condensing liquid from all sides. We take a step further and treat more realistic geometries, where a cap-shaped liquid cluster forms on the surface of the seed particle. We derive the equilibrium conditions for such a cluster. The equalities of chemical potentials of each species between the nucleus and the vapor represent the conditions of chemical equilibrium. The generalized Young equation that relates contact angle with surface tensions, surface excess polarizations, and line tension, also containing the electrical contribution from triple line excess polarization, expresses the condition of thermodynamic equilibrium at three-phase contact line. The generalized Laplace equation gives the condition of mechanical equilibrium at vapor-liquid dividing surface: it relates generalized pressures in neighboring bulk phases at an interface with surface tension, excess surface polarization, and dielectric displacements in neighboring phases with two principal radii of surface curvature and curvatures of equipotential surfaces in neighboring phases at that point. We also re-express the generalized Laplace equation as a partial differential equation, which, along with electrostatic Laplace equations for bulk phases, determines the shape of a nucleus. We derive expressions that are suitable for calculations of the size and composition of a critical nucleus (generalized version of the classical Kelvin-Thomson equation).

Mathematical and computational studies of equilibrium capillary free surfaces

NASA Technical Reports Server (NTRS)

Albright, N.; Chen, N. F.; Concus, P.; Finn, R.

1977-01-01

The results of several independent studies are presented. The general question is considered of whether a wetting liquid always rises higher in a small capillary tube than in a larger one, when both are dipped vertically into an infinite reservoir. An analytical investigation is initiated to determine the qualitative behavior of the family of solutions of the equilibrium capillary free-surface equation that correspond to rotationally symmetric pendent liquid drops and the relationship of these solutions to the singular solution, which corresponds to an infinite spike of liquid extending downward to infinity. The block successive overrelaxation-Newton method and the generalized conjugate gradient method are investigated for solving the capillary equation on a uniform square mesh in a square domain, including the case for which the solution is unbounded at the corners. Capillary surfaces are calculated on the ellipse, on a circle with reentrant notches, and on other irregularly shaped domains using JASON, a general purpose program for solving nonlinear elliptic equations on a nonuniform quadrilaterial mesh. Analytical estimates for the nonexistence of solutions of the equilibrium capillary free-surface equation on the ellipse in zero gravity are evaluated.

Dynamical quantum phase transitions: a review

NASA Astrophysics Data System (ADS)

Heyl, Markus

2018-05-01

Quantum theory provides an extensive framework for the description of the equilibrium properties of quantum matter. Yet experiments in quantum simulators have now opened up a route towards the generation of quantum states beyond this equilibrium paradigm. While these states promise to show properties not constrained by equilibrium principles, such as the equal a priori probability of the microcanonical ensemble, identifying the general properties of nonequilibrium quantum dynamics remains a major challenge, especially in view of the lack of conventional concepts such as free energies. The theory of dynamical quantum phase transitions attempts to identify such general principles by lifting the concept of phase transitions to coherent quantum real-time evolution. This review provides a pedagogical introduction to this field. Starting from the general setting of nonequilibrium dynamics in closed quantum many-body systems, we give the definition of dynamical quantum phase transitions as phase transitions in time with physical quantities becoming nonanalytic at critical times. We summarize the achieved theoretical advances as well as the first experimental observations, and furthermore provide an outlook to major open questions as well as future directions of research.

Dynamical quantum phase transitions: a review.

PubMed

Heyl, Markus

2018-05-01

Quantum theory provides an extensive framework for the description of the equilibrium properties of quantum matter. Yet experiments in quantum simulators have now opened up a route towards the generation of quantum states beyond this equilibrium paradigm. While these states promise to show properties not constrained by equilibrium principles, such as the equal a priori probability of the microcanonical ensemble, identifying the general properties of nonequilibrium quantum dynamics remains a major challenge, especially in view of the lack of conventional concepts such as free energies. The theory of dynamical quantum phase transitions attempts to identify such general principles by lifting the concept of phase transitions to coherent quantum real-time evolution. This review provides a pedagogical introduction to this field. Starting from the general setting of nonequilibrium dynamics in closed quantum many-body systems, we give the definition of dynamical quantum phase transitions as phase transitions in time with physical quantities becoming nonanalytic at critical times. We summarize the achieved theoretical advances as well as the first experimental observations, and furthermore provide an outlook to major open questions as well as future directions of research.

General equilibrium effects of a supply side GHG mitigation option under the Clean Development Mechanism.

PubMed

Timilsina, Govinda R; Shrestha, Ram M

2006-09-01

The Clean Development Mechanism (CDM) under the Kyoto Protocol to the United Nations Framework Convention on Climate Change is considered a key instrument to encourage developing countries' participation in the mitigation of global climate change. Reduction of greenhouse gas (GHG) emissions through the energy supply and demand side activities are the main options to be implemented under the CDM. This paper analyses the general equilibrium effects of a supply side GHG mitigation option-the substitution of thermal power with hydropower--in Thailand under the CDM. A static multi-sector general equilibrium model has been developed for the purpose of this study. The key finding of the study is that the substitution of electricity generation from thermal power plants with that from hydropower plants would increase economic welfare in Thailand. The supply side option would, however, adversely affect the gross domestic product (GDP) and the trade balance. The percentage changes in economic welfare, GDP and trade balance increase with the level of substitution and the price of certified emission reduction (CER) units.

IRREVERSIBLE PROCESSES IN A PLASMA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balescu, R.

1959-04-01

ABS>The characteristic divergences caused by long-range phenomena in gases can be eliminated in equilibrium situations by partial summations of terms individually divergent but whose sum converges. It is shown how the recently developed diagram technique enables treatment of non-equilibrium cases by a rigorous asymptotic method. The general ideas underlying the approach are briefly indicated. (T.R. H.)

Microeconomics, Socialization, and Norms. Program Report No. 79-B22.

ERIC Educational Resources Information Center

Field, Alexander J.

Microeconomic theory encompasses two basic theoretical concepts. First is the theory of general competitive equilibrium in a market economy, which holds that the actions of any one agent cannot affect prices or quantities for the system as a whole. The second is that when the conditions of competitive equilibrium do not apply, theories of games…

Chief Characteristics and Advantages of Tailless Airplanes

NASA Technical Reports Server (NTRS)

Dufaure De Lajarte, A

1936-01-01

This study will be concerned with the critical examination of two main questions, mainly, susceptibility of centering and more generally, the conditions of static stability, longitudinal equilibrium, and the question of dynamic stability, or at least the damping of longitudinal vibrations about a position of equilibrium that may result from a small variation in the angle of attack.

An Application of Variational Theory to an Integrated Walrasian Model of Exchange, Consumption and Production

NASA Astrophysics Data System (ADS)

Donato, M. B.; Milasi, M.; Vitanza, C.

2010-09-01

An existence result of a Walrasian equilibrium for an integrated model of exchange, consumption and production is obtained. The equilibrium model is characterized in terms of a suitable generalized quasi-variational inequality; so the existence result comes from an original technique which takes into account tools of convex and set-valued analysis.

Spontaneity and Equilibrium II: Multireaction Systems

ERIC Educational Resources Information Center

Raff, Lionel M.

2014-01-01

The thermodynamic criteria for spontaneity and equilibrium in multireaction systems are developed and discussed. When N reactions are occurring simultaneously, it is shown that G and A will depend upon N independent reaction coordinates, ?a (a = 1,2, ..., N), in addition to T and p for G or T and V for A. The general criteria for spontaneity and…

General equilibrium second-order hydrodynamic coefficients for free quantum fields

NASA Astrophysics Data System (ADS)

Buzzegoli, M.; Grossi, E.; Becattini, F.

2017-10-01

We present a systematic calculation of the corrections of the stress-energy tensor and currents of the free boson and Dirac fields up to second order in thermal vorticity, which is relevant for relativistic hydrodynamics. These corrections are non-dissipative because they survive at general thermodynamic equilibrium with non vanishing mean values of the conserved generators of the Lorentz group, i.e. angular momenta and boosts. Their equilibrium nature makes it possible to express the relevant coefficients by means of correlators of the angular-momentum and boost operators with stress-energy tensor and current, thus making simpler to determine their so-called "Kubo formulae". We show that, at least for free fields, the corrections are of quantum origin and we study several limiting cases and compare our results with previous calculations. We find that the axial current of the free Dirac field receives corrections proportional to the vorticity independently of the anomalous term.

Equivalency principle for magnetoelectroelastic multiferroics with arbitrary microstructure: The phase field approach

NASA Astrophysics Data System (ADS)

Ni, Yong; He, Linghui; Khachaturyan, Armen G.

2010-07-01

A phase field method is proposed to determine the equilibrium fields of a magnetoelectroelastic multiferroic with arbitrarily distributed constitutive constants under applied loadings. This method is based on a developed generalized Eshelby's equivalency principle, in which the elastic strain, electrostatic, and magnetostatic fields at the equilibrium in the original heterogeneous system are exactly the same as those in an equivalent homogeneous magnetoelectroelastic coupled or uncoupled system with properly chosen distributed effective eigenstrain, polarization, and magnetization fields. Finding these effective fields fully solves the equilibrium elasticity, electrostatics, and magnetostatics in the original heterogeneous multiferroic. The paper formulates a variational principle proving that the effective fields are minimizers of appropriate close-form energy functional. The proposed phase field approach produces the energy minimizing effective fields (and thus solving the general multiferroic problem) as a result of artificial relaxation process described by the Ginzburg-Landau-Khalatnikov kinetic equations.

Nonequilibrium Entropy in a Shock

DOE PAGES

Margolin, Len G.

2017-07-19

In a classic paper, Morduchow and Libby use an analytic solution for the profile of a Navier–Stokes shock to show that the equilibrium thermodynamic entropy has a maximum inside the shock. There is no general nonequilibrium thermodynamic formulation of entropy; the extension of equilibrium theory to nonequililbrium processes is usually made through the assumption of local thermodynamic equilibrium (LTE). However, gas kinetic theory provides a perfectly general formulation of a nonequilibrium entropy in terms of the probability distribution function (PDF) solutions of the Boltzmann equation. In this paper I will evaluate the Boltzmann entropy for the PDF that underlies themore » Navier–Stokes equations and also for the PDF of the Mott–Smith shock solution. I will show that both monotonically increase in the shock. As a result, I will propose a new nonequilibrium thermodynamic entropy and show that it is also monotone and closely approximates the Boltzmann entropy.« less

A dynamic analysis of the motion of a low-wing general aviation aircraft about its calculated equilibrium flat spin mode

NASA Technical Reports Server (NTRS)

Tischler, M. B.; Barlow, J. B.

1980-01-01

The properties of the flat spin mode of a general aviation configuration have been studied through analysis of rotary balance data, numerical simulation, and analytical study of the equilibrium state. The equilibrium state is predicted well from rotary balance data. The variations of yawing moment and pitching moment as functions of sideslip have been shown to be of great importance in obtaining accurate modeling. These dependencies are not presently available with sufficient accuracy from previous tests or theories. The stability of the flat spin mode has been examined extensively using numerical linearization, classical perturbation methods, and reduced order modeling. The stability exhibited by the time histories and the eigenvalue analyses is shown to be strongly dependent on certain static cross derivatives and more so on the dynamic derivatives. Explicit stability criteria are obtained from the reduced order models.

Nonequilibrium Entropy in a Shock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Margolin, Len G.

In a classic paper, Morduchow and Libby use an analytic solution for the profile of a Navier–Stokes shock to show that the equilibrium thermodynamic entropy has a maximum inside the shock. There is no general nonequilibrium thermodynamic formulation of entropy; the extension of equilibrium theory to nonequililbrium processes is usually made through the assumption of local thermodynamic equilibrium (LTE). However, gas kinetic theory provides a perfectly general formulation of a nonequilibrium entropy in terms of the probability distribution function (PDF) solutions of the Boltzmann equation. In this paper I will evaluate the Boltzmann entropy for the PDF that underlies themore » Navier–Stokes equations and also for the PDF of the Mott–Smith shock solution. I will show that both monotonically increase in the shock. As a result, I will propose a new nonequilibrium thermodynamic entropy and show that it is also monotone and closely approximates the Boltzmann entropy.« less

Addition of equilibrium air to an upwind Navier-Stokes code and other first steps toward a more generalized flow solver

NASA Technical Reports Server (NTRS)

Rosen, Bruce S.

1991-01-01

An upwind three-dimensional volume Navier-Stokes code is modified to facilitate modeling of complex geometries and flow fields represented by proposed National Aerospace Plane concepts. Code enhancements include an equilibrium air model, a generalized equilibrium gas model and several schemes to simplify treatment of complex geometric configurations. The code is also restructured for inclusion of an arbitrary number of independent and dependent variables. This latter capability is intended for eventual use to incorporate nonequilibrium/chemistry gas models, more sophisticated turbulence and transition models, or other physical phenomena which will require inclusion of additional variables and/or governing equations. Comparisons of computed results with experimental data and results obtained using other methods are presented for code validation purposes. Good correlation is obtained for all of the test cases considered, indicating the success of the current effort.

A study of the linear free energy model for DNA structures using the generalized Hamiltonian formalism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yavari, M., E-mail: yavari@iaukashan.ac.ir

2016-06-15

We generalize the results of Nesterenko [13, 14] and Gogilidze and Surovtsev [15] for DNA structures. Using the generalized Hamiltonian formalism, we investigate solutions of the equilibrium shape equations for the linear free energy model.

Entropy is in Flux V3.4

NASA Astrophysics Data System (ADS)

Kadanoff, Leo P.

2017-05-01

The science of thermodynamics was put together in the Nineteenth Century to describe large systems in equilibrium. One part of thermodynamics defines entropy for equilibrium systems and demands an ever-increasing entropy for non-equilibrium ones. Since thermodynamics does not define entropy out of equilibrium, pure thermodynamics cannot follow the details of how this increase occurs. However, starting with the work of Ludwig Boltzmann in 1872, and continuing to the present day, various models of non-equilibrium behavior have been put together with the specific aim of generalizing the concept of entropy to non-equilibrium situations. This kind of entropy has been termed kinetic entropy to distinguish it from the thermodynamic variety. Knowledge of kinetic entropy started from Boltzmann's insight about his equation for the time dependence of gaseous systems. In this paper, his result is stated as a definition of kinetic entropy in terms of a local equation for the entropy density. This definition is then applied to Landau's theory of the Fermi liquid thereby giving the kinetic entropy within that theory. The dynamics of many condensed matter systems including Fermi liquids, low temperature superfluids, and ordinary metals lend themselves to the definition of kinetic entropy. In fact, entropy has been defined and used for a wide variety of situations in which a condensed matter system has been allowed to relax for a sufficient period so that the very most rapid fluctuations have been ironed out. One of the broadest applications of non-equilibrium analysis considers quantum degenerate systems using Martin-Schwinger Green's functions (Phys Rev 115:1342-1373, 1959) as generalized Wigner functions, g^<({p},ω ,{R},T) and g^>({p},ω ,{R},T). This paper describes once again how the quantum kinetic equations for these functions give locally defined conservation laws for mass momentum and energy. In local thermodynamic equilibrium, this kinetic theory enables a reasonable definition of the density of kinetic entropy. However, when the system is outside of local equilibrium, this definition fails. It is speculated that quantum entanglement is the source of this failure.

Stability of equilibrium solutions of Hamiltonian systems with n-degrees of freedom and single resonance in the critical case

NASA Astrophysics Data System (ADS)

dos Santos, Fabio; Vidal, Claudio

2018-04-01

In this paper we give new results for the stability of one equilibrium solution of an autonomous analytic Hamiltonian system in a neighborhood of the equilibrium point with n-degrees of freedom. Our Main Theorem generalizes several results existing in the literature and mainly we give information in the critical cases (i.e., the condition of stability and instability is not fulfilled). In particular, our Main Theorem provides necessary and sufficient conditions for stability of the equilibrium solutions under the existence of a single resonance. Using analogous tools used in the Main Theorem for the critical case, we study the stability or instability of degenerate equilibrium points in Hamiltonian systems with one degree of freedom. We apply our results to the stability of Hamiltonians of the type of cosmological models as in planar as in the spatial case.

Revealing missing charges with generalised quantum fluctuation relations.

PubMed

Mur-Petit, J; Relaño, A; Molina, R A; Jaksch, D

2018-05-22

The non-equilibrium dynamics of quantum many-body systems is one of the most fascinating problems in physics. Open questions range from how they relax to equilibrium to how to extract useful work from them. A critical point lies in assessing whether a system has conserved quantities (or 'charges'), as these can drastically influence its dynamics. Here we propose a general protocol to reveal the existence of charges based on a set of exact relations between out-of-equilibrium fluctuations and equilibrium properties of a quantum system. We apply these generalised quantum fluctuation relations to a driven quantum simulator, demonstrating their relevance to obtain unbiased temperature estimates from non-equilibrium measurements. Our findings will help guide research on the interplay of quantum and thermal fluctuations in quantum simulation, in studying the transition from integrability to chaos and in the design of new quantum devices.

Detecting temperature fluctuations at equilibrium.

PubMed

Dixit, Purushottam D

2015-05-21

The Gibbs and the Boltzmann definition of temperature agree only in the macroscopic limit. The ambiguity in identifying the equilibrium temperature of a finite-sized 'small' system exchanging energy with a bath is usually understood as a limitation of conventional statistical mechanics. We interpret this ambiguity as resulting from a stochastically fluctuating temperature coupled with the phase space variables giving rise to a broad temperature distribution. With this ansatz, we develop the equilibrium statistics and dynamics of small systems. Numerical evidence using an analytically tractable model shows that the effects of temperature fluctuations can be detected in the equilibrium and dynamical properties of the phase space of the small system. Our theory generalizes statistical mechanics to small systems relevant in biophysics and nanotechnology.

He I lines in B stars - Comparison of non-local thermodynamic equilibrium models with observations

NASA Technical Reports Server (NTRS)

Heasley, J. N.; Timothy, J. G.; Wolff, S. C.

1982-01-01

Profiles of He gamma-gamma 4026, 4387, 4471, 4713, 5876, and 6678 have been obtained in 17 stars of spectral type B0-B5. Parameters of the nonlocal thermodynamic equilibrium models appropriate to each star are determined from the Stromgren index and fits to H-alpha line profiles. These parameters yield generally good fits to the observed He I line profiles, with the best fits being found for the blue He I lines where departures from local thermodynamic equilibrium are relatively small. For the two red lines it is found that, in the early B stars and in stars with log g less than 3.5, both lines are systematically stronger than predicted by the nonlocal thermodynamic equilibrium models.

Real payoffs and virtual trading in agent based market models

NASA Astrophysics Data System (ADS)

Ferreira, Fernando F.; Marsili, Matteo

2005-01-01

The -Game was recently introduced as an extension of the Minority Game. In this paper we compare this model with the well know Minority Game and the Majority Game models. Due to the inter-temporal nature of the market payoff, we introduce a two step transaction with single and mixed group of interacting traders. When the population is composed of two different group of -traders, they show an anti-imitative behavior. However, when they interact with minority or majority players the $-population imitates the usual behavior of these players. Finally we discuss how these models contribute to clarify the market mechanism.

Sunday Liquor Laws and Crime

PubMed Central

Heaton, Paul

2011-01-01

Many jurisdictions have considered relaxing Sunday alcohol sales restrictions, yet such restrictions' effects on public health remain poorly understood. This paper analyzes the effects of legalization of Sunday packaged liquor sales on crime, focusing on the phased introduction of such sales in Virginia beginning in 2004. Differences-in-differences and triple-differences estimates indicate the liberalization increased minor crime by 5% and alcohol-involved serious crime by 10%. The law change did not affect domestic crime or induce significant geographic or inter-temporal crime displacement. The costs of this additional crime are comparable to the state's revenues from increased liquor sales. PMID:22125348

Similarities and Differences in Psychology.

PubMed

Chen, Yu; Sun, Yan; Ai, Si-Zhi; Li, Jason J; Lu, Lin; Shi, Jie

2017-01-01

Addiction is marked by repeating a certain behavior while ignoring the potential physical or mental consequences. Non-substance addiction provides an ideal model for researching the emergence and development of addiction's basic mechanism. Comparative studies of substance and non-substance addiction are helpful to reveal the common basis of addiction development. This article explores this topic from a psychological angle, touching upon sensation seeking, inhibitory control, attentional bias, intertemporal choice and environment. A review of previous literature urges future research to propose a biopsychosocial model of addiction and consider addiction's effect on basic cognitive function alongside cognitive neuroscience technology.

Migration plans and hours of work in Malaysia.

PubMed

Gillin, E D; Sumner, D A

1985-01-01

"This article describes characteristics of prospective migrants in the Malaysian Family Life Survey and investigates how planning to move affects hours of work. [The authors] use ideas about intertemporal substitution...to discuss the response to temporary and permanent wage expectations on the part of potential migrants. [An] econometric section presents reduced-form estimates for wage rates and planned migration equations and two-stage least squares estimates for hours of work. Men currently planning a move were found to work fewer hours. Those originally planning only a temporary stay at their current location work more hours." excerpt

The futility of utility: how market dynamics marginalize Adam Smith

NASA Astrophysics Data System (ADS)

McCauley, Joseph L.

2000-10-01

Economic theorizing is based on the postulated, nonempiric notion of utility. Economists assume that prices, dynamics, and market equilibria are supposed to be derived from utility. The results are supposed to represent mathematically the stabilizing action of Adam Smith's invisible hand. In deterministic excess demand dynamics I show the following. A utility function generally does not exist mathematically due to nonintegrable dynamics when production/investment are accounted for, resolving Mirowski's thesis. Price as a function of demand does not exist mathematically either. All equilibria are unstable. I then explain how deterministic chaos can be distinguished from random noise at short times. In the generalization to liquid markets and finance theory described by stochastic excess demand dynamics, I also show the following. Market price distributions cannot be rescaled to describe price movements as ‘equilibrium’ fluctuations about a systematic drift in price. Utility maximization does not describe equilibrium. Maximization of the Gibbs entropy of the observed price distribution of an asset would describe equilibrium, if equilibrium could be achieved, but equilibrium does not describe real, liquid markets (stocks, bonds, foreign exchange). There are three inconsistent definitions of equilibrium used in economics and finance, only one of which is correct. Prices in unregulated free markets are unstable against both noise and rising or falling expectations: Adam Smith's stabilizing invisible hand does not exist, either in mathematical models of liquid market data, or in real market data.

Role of grain size and particle velocity distribution in secondary electron emission in space plasmas

NASA Technical Reports Server (NTRS)

Chow, V. W.; Mendis, D. A.; Rosenberg, M.

1993-01-01

By virtue of being generally immersed in a plasma environment, cosmic dust is necessarily electrically charged. The fact that secondary emission plays an important role in determining the equilibrium grain potential has long been recognized, but the fact that the grain size plays a crucial role in this equilibrium potential, when secondary emission is important, has not been widely appreciated. Using both conducting and insulating spherical grains of various sizes and also both Maxwellian and generalized Lorentzian plasmas (which are believed to represent certain space plasmas), we have made a detailed study of this problem. In general, we find that the secondary emission yield delta increases with decreasing size and becomes very large for grains whose dimensions are comparable to the primary electron penetration depth, such as in the case of the very small grains observed at comet Halley and inferred in the interstellar medium. Moreover, we observed that delta is larger for insulators and equilibrium potentials are generally more positive when the plasma has a broad non-Maxwellian tail. Interestingly, we find that for thermal energies that are expected in several cosmic regions, grains of different sizes can have opposite charge, the smaller ones being positive while the larger ones are negative. This may have important consequences for grain accretion in polydisperse dusty space plasmas.

Using Beads and Divided Containers to Study Kinetic and Equilibrium Isotope Effects in the Laboratory and in the Classroom

ERIC Educational Resources Information Center

Campbell, Dean J.; Brewer, Emily R.; Martinez, Keri A.; Fitzjarrald, Tamara J.

2017-01-01

The purpose of this laboratory experiment is to study fundamental concepts of kinetics and equilibria and the isotope effects associated with both of these concepts. The concepts of isotopes in introductory and general chemistry courses are typically used within the contexts of atomic weights and radioactivity. Kinetic and equilibrium isotope…

Stresses in non-equilibrium fluids: Exact formulation and coarse-grained theory.

PubMed

Krüger, Matthias; Solon, Alexandre; Démery, Vincent; Rohwer, Christian M; Dean, David S

2018-02-28

Starting from the stochastic equation for the density operator, we formulate the exact (instantaneous) stress tensor for interacting Brownian particles and show that its average value agrees with expressions derived previously. We analyze the relation between the stress tensor and forces due to external potentials and observe that, out of equilibrium, particle currents give rise to extra forces. Next, we derive the stress tensor for a Landau-Ginzburg theory in generic, non-equilibrium situations, finding an expression analogous to that of the exact microscopic stress tensor, and discuss the computation of out-of-equilibrium (classical) Casimir forces. Subsequently, we give a general form for the stress tensor which is valid for a large variety of energy functionals and which reproduces the two mentioned cases. We then use these relations to study the spatio-temporal correlations of the stress tensor in a Brownian fluid, which we compute to leading order in the interaction potential strength. We observe that, after integration over time, the spatial correlations generally decay as power laws in space. These are expected to be of importance for driven confined systems. We also show that divergence-free parts of the stress tensor do not contribute to the Green-Kubo relation for the viscosity.

Static Analysis of Large-Scale Multibody System Using Joint Coordinates and Spatial Algebra Operator

PubMed Central

Omar, Mohamed A.

2014-01-01

Initial transient oscillations inhibited in the dynamic simulations responses of multibody systems can lead to inaccurate results, unrealistic load prediction, or simulation failure. These transients could result from incompatible initial conditions, initial constraints violation, and inadequate kinematic assembly. Performing static equilibrium analysis before the dynamic simulation can eliminate these transients and lead to stable simulation. Most exiting multibody formulations determine the static equilibrium position by minimizing the system potential energy. This paper presents a new general purpose approach for solving the static equilibrium in large-scale articulated multibody. The proposed approach introduces an energy drainage mechanism based on Baumgarte constraint stabilization approach to determine the static equilibrium position. The spatial algebra operator is used to express the kinematic and dynamic equations of the closed-loop multibody system. The proposed multibody system formulation utilizes the joint coordinates and modal elastic coordinates as the system generalized coordinates. The recursive nonlinear equations of motion are formulated using the Cartesian coordinates and the joint coordinates to form an augmented set of differential algebraic equations. Then system connectivity matrix is derived from the system topological relations and used to project the Cartesian quantities into the joint subspace leading to minimum set of differential equations. PMID:25045732

Stresses in non-equilibrium fluids: Exact formulation and coarse-grained theory

NASA Astrophysics Data System (ADS)

Krüger, Matthias; Solon, Alexandre; Démery, Vincent; Rohwer, Christian M.; Dean, David S.

2018-02-01

Starting from the stochastic equation for the density operator, we formulate the exact (instantaneous) stress tensor for interacting Brownian particles and show that its average value agrees with expressions derived previously. We analyze the relation between the stress tensor and forces due to external potentials and observe that, out of equilibrium, particle currents give rise to extra forces. Next, we derive the stress tensor for a Landau-Ginzburg theory in generic, non-equilibrium situations, finding an expression analogous to that of the exact microscopic stress tensor, and discuss the computation of out-of-equilibrium (classical) Casimir forces. Subsequently, we give a general form for the stress tensor which is valid for a large variety of energy functionals and which reproduces the two mentioned cases. We then use these relations to study the spatio-temporal correlations of the stress tensor in a Brownian fluid, which we compute to leading order in the interaction potential strength. We observe that, after integration over time, the spatial correlations generally decay as power laws in space. These are expected to be of importance for driven confined systems. We also show that divergence-free parts of the stress tensor do not contribute to the Green-Kubo relation for the viscosity.

Static analysis of large-scale multibody system using joint coordinates and spatial algebra operator.

PubMed

Omar, Mohamed A

2014-01-01

Initial transient oscillations inhibited in the dynamic simulations responses of multibody systems can lead to inaccurate results, unrealistic load prediction, or simulation failure. These transients could result from incompatible initial conditions, initial constraints violation, and inadequate kinematic assembly. Performing static equilibrium analysis before the dynamic simulation can eliminate these transients and lead to stable simulation. Most exiting multibody formulations determine the static equilibrium position by minimizing the system potential energy. This paper presents a new general purpose approach for solving the static equilibrium in large-scale articulated multibody. The proposed approach introduces an energy drainage mechanism based on Baumgarte constraint stabilization approach to determine the static equilibrium position. The spatial algebra operator is used to express the kinematic and dynamic equations of the closed-loop multibody system. The proposed multibody system formulation utilizes the joint coordinates and modal elastic coordinates as the system generalized coordinates. The recursive nonlinear equations of motion are formulated using the Cartesian coordinates and the joint coordinates to form an augmented set of differential algebraic equations. Then system connectivity matrix is derived from the system topological relations and used to project the Cartesian quantities into the joint subspace leading to minimum set of differential equations.

Multiphase, multicomponent phase behavior prediction

NASA Astrophysics Data System (ADS)

Dadmohammadi, Younas

Accurate prediction of phase behavior of fluid mixtures in the chemical industry is essential for designing and operating a multitude of processes. Reliable generalized predictions of phase equilibrium properties, such as pressure, temperature, and phase compositions offer an attractive alternative to costly and time consuming experimental measurements. The main purpose of this work was to assess the efficacy of recently generalized activity coefficient models based on binary experimental data to (a) predict binary and ternary vapor-liquid equilibrium systems, and (b) characterize liquid-liquid equilibrium systems. These studies were completed using a diverse binary VLE database consisting of 916 binary and 86 ternary systems involving 140 compounds belonging to 31 chemical classes. Specifically the following tasks were undertaken: First, a comprehensive assessment of the two common approaches (gamma-phi (gamma-ϕ) and phi-phi (ϕ-ϕ)) used for determining the phase behavior of vapor-liquid equilibrium systems is presented. Both the representation and predictive capabilities of these two approaches were examined, as delineated form internal and external consistency tests of 916 binary systems. For the purpose, the universal quasi-chemical (UNIQUAC) model and the Peng-Robinson (PR) equation of state (EOS) were used in this assessment. Second, the efficacy of recently developed generalized UNIQUAC and the nonrandom two-liquid (NRTL) for predicting multicomponent VLE systems were investigated. Third, the abilities of recently modified NRTL model (mNRTL2 and mNRTL1) to characterize liquid-liquid equilibria (LLE) phase conditions and attributes, including phase stability, miscibility, and consolute point coordinates, were assessed. The results of this work indicate that the ϕ-ϕ approach represents the binary VLE systems considered within three times the error of the gamma-ϕ approach. A similar trend was observed for the for the generalized model predictions using quantitative structure-property parameter generalizations (QSPR). For ternary systems, where all three constituent binary systems were available, the NRTL-QSPR, UNIQUAC-QSPR, and UNIFAC-6 models produce comparable accuracy. For systems where at least one constituent binary is missing, the UNIFAC-6 model produces larger errors than the QSPR generalized models. In general, the LLE characterization results indicate the accuracy of the modified models in reproducing the findings of the original NRTL model.

A Harris-Todaro Agent-Based Model to Rural-Urban Migration

NASA Astrophysics Data System (ADS)

Espíndola, Aquino L.; Silveira, Jaylson J.; Penna, T. J. P.

2006-09-01

The Harris-Todaro model of the rural-urban migration process is revisited under an agent-based approach. The migration of the workers is interpreted as a process of social learning by imitation, formalized by a computational model. By simulating this model, we observe a transitional dynamics with continuous growth of the urban fraction of overall population toward an equilibrium. Such an equilibrium is characterized by stabilization of rural-urban expected wages differential (generalized Harris-Todaro equilibrium condition), urban concentration and urban unemployment. These classic results obtained originally by Harris and Todaro are emergent properties of our model.

A Heuristic Approach to Examining Volatile Equilibrium at Titan's Surface

NASA Technical Reports Server (NTRS)

Samuelson, Robert E.

1999-01-01

R. D. Lorenz, J. I. Lunine, and C. P. McKay have shown in a manuscript accepted for publication that, for a given ethane abundance and surface temperature, the nitrogen and methane abundances in Titan's atmosphere can be calculated, yielding a surface pressure that can be compared with the observed value. This is potentially a very valuable tool for examining the evolution of Titan's climatology. Its validity does depend on two important assumptions, however: 1) that the atmosphere of Titan is in global radiative equilibrium, and 2) that volatiles present are in vapor equilibrium with the surface. The former assumption has been shown to be likely, but the latter has not. Water vapor in the Earth's atmosphere, in fact, is generally not very close to equilibrium in a global sense. In the present work a heuristic approach is used to examine the likelihood that methane vapor is in equilibrium with Titan's surface. Plausible climate scenerios are examined that are consistent with methane vapor abundances derived from Voyager IRIS data. Simple precipitation and surface diffusion models are incorporated into the analysis. It is tentatively inferred that methane may be in surface equilibrium near the poles, but that equilibrium at low latitudes is more difficult to establish.

Latitudinal oscillations of plasma within the Io torus

NASA Technical Reports Server (NTRS)

Cummings, W. D.; Dessler, A. J.; Hill, T. W.

1980-01-01

The equilibrium latitude and the period of oscillations about this equilibrium latitude are calculated for a plasma in a centrifugally dominated tilted dipole magnetic field representing Jupiter's inner magnetosphere. It is found that for a hot plasma the equilibrium latitude in the magnetic equator, for a cold plasma it is the centrifugal equator, and for a warm plasma it is somewhere in between. An illustrative model is adopted in which atoms are sputtered from the Jupiter-facing hemisphere of Io and escape Io's gravity to be subsequently ionized some distance from Io. Finally, it is shown that ionization generally does not occur at the equilibrium altitude, and that the resulting latitudinal oscillations provide an explanation for the irregularities in electron concentration within the torus, as reported by the radioastronomy experiment aboard Voyager I.

Equilibrium stochastic dynamics of a Brownian particle in inhomogeneous space: Derivation of an alternative model

NASA Astrophysics Data System (ADS)

Bhattacharyay, A.

2018-03-01

An alternative equilibrium stochastic dynamics for a Brownian particle in inhomogeneous space is derived. Such a dynamics can model the motion of a complex molecule in its conformation space when in equilibrium with a uniform heat bath. The derivation is done by a simple generalization of the formulation due to Zwanzig for a Brownian particle in homogeneous heat bath. We show that, if the system couples to different number of bath degrees of freedom at different conformations then the alternative model gets derived. We discuss results of an experiment by Faucheux and Libchaber which probably has indicated possible limitation of the Boltzmann distribution as equilibrium distribution of a Brownian particle in inhomogeneous space and propose experimental verification of the present theory using similar methods.

Nuclear spin polarized H and D by means of spin-exchange optical pumping

NASA Astrophysics Data System (ADS)

Stenger, Jörn; Grosshauser, Carsten; Kilian, Wolfgang; Nagengast, Wolfgang; Ranzenberger, Bernd; Rith, Klaus; Schmidt, Frank

1998-01-01

Optically pumped spin-exchange sources for polarized hydrogen and deuterium atoms have been demonstrated to yield high atomic flow and high electron spin polarization. For maximum nuclear polarization the source has to be operated in spin temperature equilibrium, which has already been demonstrated for hydrogen. In spin temperature equilibrium the nuclear spin polarization PI equals the electron spin polarization PS for hydrogen and is even larger than PS for deuterium. We discuss the general properties of spin temperature equilibrium for a sample of deuterium atoms. One result are the equations PI=4PS/(3+PS2) and Pzz=PSṡPI, where Pzz is the nuclear tensor polarization. Furthermore we demonstrate that the deuterium atoms from our source are in spin temperature equilibrium within the experimental accuracy.

Equilibrium pricing in an order book environment: Case study for a spin model

NASA Astrophysics Data System (ADS)

Meudt, Frederik; Schmitt, Thilo A.; Schäfer, Rudi; Guhr, Thomas

2016-07-01

When modeling stock market dynamics, the price formation is often based on an equilibrium mechanism. In real stock exchanges, however, the price formation is governed by the order book. It is thus interesting to check if the resulting stylized facts of a model with equilibrium pricing change, remain the same or, more generally, are compatible with the order book environment. We tackle this issue in the framework of a case study by embedding the Bornholdt-Kaizoji-Fujiwara spin model into the order book dynamics. To this end, we use a recently developed agent based model that realistically incorporates the order book. We find realistic stylized facts. We conclude for the studied case that equilibrium pricing is not needed and that the corresponding assumption of a ;fundamental; price may be abandoned.

Examples of equilibrium and non-equilibrium behavior in evolutionary systems

NASA Astrophysics Data System (ADS)

Soulier, Arne

With this thesis, we want to shed some light into the darkness of our understanding of simply defined statistical mechanics systems and the surprisingly complex dynamical behavior they exhibit. We will do so by presenting in turn one equilibrium and then one non-equilibrium system with evolutionary dynamics. In part 1, we will present the seceder-model, a newly developed system that cannot equilibrate. We will then study several properties of the system and obtain an idea of the richness of the dynamics of the seceder model, which is particular impressive given the minimal amount of modeling necessary in its setup. In part 2, we will present extensions to the directed polymer in random media problem on a hypercube and its connection to the Eigen model of evolution. Our main interest will be the influence of time-dependent and time-independent changes in the fitness landscape viewed by an evolving population. This part contains the equilibrium dynamics. The stochastic models and the topic of evolution and non-equilibrium in general will allow us to point out similarities to the various lines of thought in game theory.

Effect of quinolinic acid-induced lesions of the nucleus accumbens core on performance on a progressive ratio schedule of reinforcement: implications for inter-temporal choice.

PubMed

Bezzina, G; Body, S; Cheung, T H C; Hampson, C L; Deakin, J F W; Anderson, I M; Szabadi, E; Bradshaw, C M

2008-04-01

The nucleus accumbens core (AcbC) is believed to contribute to the control of operant behaviour by reinforcers. Recent evidence suggests that it is not crucial for determining the incentive value of immediately available reinforcers, but is important for maintaining the values of delayed reinforcers. This study aims to examine the effect of AcbC lesions on performance on a progressive-ratio schedule using a quantitative model that dissociates effects of interventions on motor and motivational processes (Killeen 1994 Mathematical principles of reinforcement. Behav Brain Sci 17:105-172). Rats with bilateral quinolinic acid-induced lesions of the AcbC (n = 15) or sham lesions (n = 14) were trained to lever-press for food-pellet reinforcers under a progressive-ratio schedule. In Phase 1 (90 sessions) the reinforcer was one pellet; in Phase 2 (30 sessions), it was two pellets; in Phase 3, (30 sessions) it was one pellet. The performance of both groups conformed to the model of progressive-ratio performance (group mean data: r2 > 0.92). The motor parameter, delta, was significantly higher in the AcbC-lesioned than the sham-lesioned group, reflecting lower overall response rates in the lesioned group. The motivational parameter, a, was sensitive to changes in reinforcer size, but did not differ significantly between the two groups. The AcbC-lesioned group showed longer post-reinforcement pauses and lower running response rates than the sham-lesioned group. The results suggest that destruction of the AcbC impairs response capacity but does not alter the efficacy of food reinforcers. The results are consistent with recent findings that AcbC lesions do not alter sensitivity to reinforcer size in inter-temporal choice schedules.

Some General Thoughts about Broken Symmetry.

DTIC Science & Technology

1981-01-21

to what extent one may generalize to random systems and to ’dissipative structures’. Thermal equilibrium broken symmetry is characterized by an order...stable defects. We conjecture what may be the consequences of relaxing these assumptions. (Author)

Rapid computation of chemical equilibrium composition - An application to hydrocarbon combustion

NASA Technical Reports Server (NTRS)

Erickson, W. D.; Prabhu, R. K.

1986-01-01

A scheme for rapidly computing the chemical equilibrium composition of hydrocarbon combustion products is derived. A set of ten governing equations is reduced to a single equation that is solved by the Newton iteration method. Computation speeds are approximately 80 times faster than the often used free-energy minimization method. The general approach also has application to many other chemical systems.

Identifying Liquid-Gas System Misconceptions and Addressing Them Using a Laboratory Exercise on Pressure-Temperature Diagrams of a Mixed Gas Involving Liquid-Vapor Equilibrium

ERIC Educational Resources Information Center

Yoshikawa, Masahiro; Koga, Nobuyoshi

2016-01-01

This study focuses on students' understandings of a liquid-gas system with liquid-vapor equilibrium in a closed system using a pressure-temperature ("P-T") diagram. By administrating three assessment questions concerning the "P-T" diagrams of liquid-gas systems to students at the beginning of undergraduate general chemistry…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pugliese, D.; Stuchlík, Z., E-mail: d.pugliese.physics@gmail.com, E-mail: zdenek.stuchlik@physics.cz

We analyze the possibility that several instability points may be formed, due to the Paczyński mechanism of violation of mechanical equilibrium, in the orbiting matter around a supermassive Kerr black hole. We consider a recently proposed model of a ringed accretion disk, made up by several tori (rings) that can be corotating or counter-rotating relative to the Kerr attractor due to the history of the accretion process. Each torus is governed by the general relativistic hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. We prove that the number of the instability points is generally limited and depends onmore » the dimensionless spin of the rotating attractor.« less

First passage analysis of the folding of a β-sheet miniprotein: is it more realistic than the standard equilibrium approach?

PubMed

Kalgin, Igor V; Chekmarev, Sergei F; Karplus, Martin

2014-04-24

Simulations of first-passage folding of the antiparallel β-sheet miniprotein beta3s, which has been intensively studied under equilibrium conditions by A. Caflisch and co-workers, show that the kinetics and dynamics are significantly different from those for equilibrium folding. Because the folding of a protein in a living system generally corresponds to the former (i.e., the folded protein is stable and unfolding is a rare event), the difference is of interest. In contrast to equilibrium folding, the Ch-curl conformations become very rare because they contain unfavorable parallel β-strand arrangements, which are difficult to form dynamically due to the distant N- and C-terminal strands. At the same time, the formation of helical conformations becomes much easier (particularly in the early stage of folding) due to short-range contacts. The hydrodynamic descriptions of the folding reaction have also revealed that while the equilibrium flow field presented a collection of local vortices with closed "streamlines", the first-passage folding is characterized by a pronounced overall flow from the unfolded states to the native state. The flows through the locally stable structures Cs-or and Ns-or, which are conformationally close to the native state, are negligible due to detailed balance established between these structures and the native state. Although there are significant differences in the general picture of the folding process from the equilibrium and first-passage folding simulations, some aspects of the two are in agreement. The rate of transitions between the clusters of characteristic protein conformations in both cases decreases approximately exponentially with the distance between the clusters in the hydrogen bond distance space of collective variables, and the folding time distribution in the first-passage segments of the equilibrium trajectory is in good agreement with that for the first-passage folding simulations.

First Passage Analysis of the Folding of a β-Sheet Miniprotein: Is it More Realistic Than the Standard Equilibrium Approach?

PubMed Central

2015-01-01

Simulations of first-passage folding of the antiparallel β-sheet miniprotein beta3s, which has been intensively studied under equilibrium conditions by A. Caflisch and co-workers, show that the kinetics and dynamics are significantly different from those for equilibrium folding. Because the folding of a protein in a living system generally corresponds to the former (i.e., the folded protein is stable and unfolding is a rare event), the difference is of interest. In contrast to equilibrium folding, the Ch-curl conformations become very rare because they contain unfavorable parallel β-strand arrangements, which are difficult to form dynamically due to the distant N- and C-terminal strands. At the same time, the formation of helical conformations becomes much easier (particularly in the early stage of folding) due to short-range contacts. The hydrodynamic descriptions of the folding reaction have also revealed that while the equilibrium flow field presented a collection of local vortices with closed ”streamlines”, the first-passage folding is characterized by a pronounced overall flow from the unfolded states to the native state. The flows through the locally stable structures Cs-or and Ns-or, which are conformationally close to the native state, are negligible due to detailed balance established between these structures and the native state. Although there are significant differences in the general picture of the folding process from the equilibrium and first-passage folding simulations, some aspects of the two are in agreement. The rate of transitions between the clusters of characteristic protein conformations in both cases decreases approximately exponentially with the distance between the clusters in the hydrogen bond distance space of collective variables, and the folding time distribution in the first-passage segments of the equilibrium trajectory is in good agreement with that for the first-passage folding simulations. PMID:24669953

Teaching Chemical Equilibrium with the Jigsaw Technique

NASA Astrophysics Data System (ADS)

Doymus, Kemal

2008-03-01

This study investigates the effect of cooperative learning (jigsaw) versus individual learning methods on students’ understanding of chemical equilibrium in a first-year general chemistry course. This study was carried out in two different classes in the department of primary science education during the 2005-2006 academic year. One of the classes was randomly assigned as the non-jigsaw group (control) and other as the jigsaw group (cooperative). Students participating in the jigsaw group were divided into four “home groups” since the topic chemical equilibrium is divided into four subtopics (Modules A, B, C and D). Each of these home groups contained four students. The groups were as follows: (1) Home Group A (HGA), representin g the equilibrium state and quantitative aspects of equilibrium (Module A), (2) Home Group B (HGB), representing the equilibrium constant and relationships involving equilibrium constants (Module B), (3) Home Group C (HGC), representing Altering Equilibrium Conditions: Le Chatelier’s principle (Module C), and (4) Home Group D (HGD), representing calculations with equilibrium constants (Module D). The home groups then broke apart, like pieces of a jigsaw puzzle, and the students moved into jigsaw groups consisting of members from the other home groups who were assigned the same portion of the material. The jigsaw groups were then in charge of teaching their specific subtopic to the rest of the students in their learning group. The main data collection tool was a Chemical Equilibrium Achievement Test (CEAT), which was applied to both the jigsaw and non-jigsaw groups The results indicated that the jigsaw group was more successful than the non-jigsaw group (individual learning method).

Hidden symmetries and equilibrium properties of multiplicative white-noise stochastic processes

NASA Astrophysics Data System (ADS)

González Arenas, Zochil; Barci, Daniel G.

2012-12-01

Multiplicative white-noise stochastic processes continue to attract attention in a wide area of scientific research. The variety of prescriptions available for defining them makes the development of general tools for their characterization difficult. In this work, we study equilibrium properties of Markovian multiplicative white-noise processes. For this, we define the time reversal transformation for such processes, taking into account that the asymptotic stationary probability distribution depends on the prescription. Representing the stochastic process in a functional Grassmann formalism, we avoid the necessity of fixing a particular prescription. In this framework, we analyze equilibrium properties and study hidden symmetries of the process. We show that, using a careful definition of the equilibrium distribution and taking into account the appropriate time reversal transformation, usual equilibrium properties are satisfied for any prescription. Finally, we present a detailed deduction of a covariant supersymmetric formulation of a multiplicative Markovian white-noise process and study some of the constraints that it imposes on correlation functions using Ward-Takahashi identities.

Competitive Cyber-Insurance and Internet Security

NASA Astrophysics Data System (ADS)

Shetty, Nikhil; Schwartz, Galina; Felegyhazi, Mark; Walrand, Jean

This paper investigates how competitive cyber-insurers affect network security and welfare of the networked society. In our model, a user's probability to incur damage (from being attacked) depends on both his security and the network security, with the latter taken by individual users as given. First, we consider cyberinsurers who cannot observe (and thus, affect) individual user security. This asymmetric information causes moral hazard. Then, for most parameters, no equilibrium exists: the insurance market is missing. Even if an equilibrium exists, the insurance contract covers only a minor fraction of the damage; network security worsens relative to the no-insurance equilibrium. Second, we consider insurers with perfect information about their users' security. Here, user security is perfectly enforceable (zero cost); each insurance contract stipulates the required user security. The unique equilibrium contract covers the entire user damage. Still, for most parameters, network security worsens relative to the no-insurance equilibrium. Although cyber-insurance improves user welfare, in general, competitive cyber-insurers fail to improve network security.

Macroscopic Fluctuation Theory for Stationary Non-Equilibrium States

NASA Astrophysics Data System (ADS)

Bertini, L.; de Sole, A.; Gabrielli, D.; Jona-Lasinio, G.; Landim, C.

2002-05-01

We formulate a dynamical fluctuation theory for stationary non-equilibrium states (SNS) which is tested explicitly in stochastic models of interacting particles. In our theory a crucial role is played by the time reversed dynamics. Within this theory we derive the following results: the modification of the Onsager-Machlup theory in the SNS; a general Hamilton-Jacobi equation for the macroscopic entropy; a non-equilibrium, nonlinear fluctuation dissipation relation valid for a wide class of systems; an H theorem for the entropy. We discuss in detail two models of stochastic boundary driven lattice gases: the zero range and the simple exclusion processes. In the first model the invariant measure is explicitly known and we verify the predictions of the general theory. For the one dimensional simple exclusion process, as recently shown by Derrida, Lebowitz, and Speer, it is possible to express the macroscopic entropy in terms of the solution of a nonlinear ordinary differential equation; by using the Hamilton-Jacobi equation, we obtain a logically independent derivation of this result.

Universality of electronic friction. II. Equivalence of the quantum-classical Liouville equation approach with von Oppen's nonequilibrium Green's function methods out of equilibrium

NASA Astrophysics Data System (ADS)

Dou, Wenjie; Subotnik, Joseph E.

2018-02-01

In a recent publication [W. Dou et al., Phys. Rev. Lett. 119, 046001 (2017), 10.1103/PhysRevLett.119.046001], using the quantum-classical Liouville equation (QCLE), we derived a very general form for the electronic friction felt by a molecule moving near one or many metal surfaces. Moreover, we have already proved the equivalence of the QCLE electronic friction with the Head-Gordon-Tully model as well as a generalized version of von Oppen's nonequilibrium Green's function (NEGF) method at equilibrium [W. Dou and J. E. Subotnik, Phys. Rev. B 96, 104305 (2017), 10.1103/PhysRevB.96.104305]. In the present paper, we now further prove the equivalence between the QCLE friction and the NEGF friction for the case of multiple metal surfaces and an out-of-equilibrium electronic current without electron-electron interactions. The present results reinforce our recent claim that there is only one universal electronic friction tensor arising from the Born-Oppenheimer approximation.

Geologic map of the Agnesi quadrangle (V-45), Venus

USGS Publications Warehouse

Hansen, Vicki L.; Tharalson, Erik R.

2014-01-01

Two general classes of hypotheses have emerged to address the near random spatial distribution of ~970 apparently pristine impact craters across the surface of Venus: (1) catastrophic/episodic resurfacing and (2) equilibrium/evolutionary resurfacing. Catastrophic/episodic hypotheses propose that a global-scale, temporally punctuated event or events dominated Venus’ evolution and that the generally uniform impact crater distribution (Schaber and others, 1992; Phillips and others, 1992; Herrick and others, 1997) reflects craters that accumulated during relative global quiescence since that event (for example, Strom and others, 1994; Herrick, 1994; Turcotte and others, 1999). Equilibrium/evolutionary hypotheses suggest instead that the near random crater distribution results from relatively continuous, but spatially localized, resurfacing in which volcanic and (or) tectonic processes occur across the planet through time, although the style of operative processes may have varied temporally and spatially (for example, Phillips and others, 1992; Guest and Stofan, 1999; Hansen and Young, 2007). Geologic relations within the map area allow us to test the catastrophic/episodic versus equilibrium/evolutionary resurfacing hypotheses.

Cooperativity in self-limiting equilibrium self-associating systems

NASA Astrophysics Data System (ADS)

Freed, Karl F.

2012-11-01

A wide variety of highly cooperative self-assembly processes in biological and synthetic systems involve the assembly of a large number (m) of units into clusters, with m narrowly peaked about a large size m0 ≫ 1 and with a second peak centered about the m = 1 unassembled monomers. While very specific models have been proposed for the assembly of, for example, viral capsids and core-shell micelles of ß-casein, no available theory describes a thermodynamically general mechanism for this double peaked, highly cooperative equilibrium assembly process. This study provides a general mechanism for these cooperative processes by developing a minimal Flory-Huggins type theory. Beginning from the simplest non-cooperative, free association model in which the equilibrium constant for addition of a monomer to a cluster is independent of cluster size, the new model merely allows more favorable growth for clusters of intermediate sizes. The theory is illustrated by computing the phase diagram for cases of self-assembly on cooling or heating and for the mass distribution of the two phases.

A Nonequilibrium Rate Formula for Collective Motions of Complex Molecular Systems

NASA Astrophysics Data System (ADS)

Yanao, Tomohiro; Koon, Wang Sang; Marsden, Jerrold E.

2010-09-01

We propose a compact reaction rate formula that accounts for a non-equilibrium distribution of residence times of complex molecules, based on a detailed study of the coarse-grained phase space of a reaction coordinate. We take the structural transition dynamics of a six-atom Morse cluster between two isomers as a prototype of multi-dimensional molecular reactions. Residence time distribution of one of the isomers shows an exponential decay, while that of the other isomer deviates largely from the exponential form and has multiple peaks. Our rate formula explains such equilibrium and non-equilibrium distributions of residence times in terms of the rates of diffusions of energy and the phase of the oscillations of the reaction coordinate. Rapid diffusions of energy and the phase generally give rise to the exponential decay of residence time distribution, while slow diffusions give rise to a non-exponential decay with multiple peaks. We finally make a conjecture about a general relationship between the rates of the diffusions and the symmetry of molecular mass distributions.

Exact mapping between different dynamics of isotropically trapped quantum gases

NASA Astrophysics Data System (ADS)

Wamba, Etienne; Pelster, Axel; Anglin, James R.

2016-05-01

Experiments on trapped quantum gases can probe challenging regimes of quantum many-body dynamics, where strong interactions or non-equilibrium states prevent exact theoretical treatment. In this talk, we present a class of exact mappings between all the observables of different experiments, under the experimentally attainable conditions that the gas particles interact via a homogeneously scaling two-body potential which is in general time-dependent, and are confined in an isotropic harmonic trap. We express our result through an identity relating second-quantized field operators in the Heisenberg picture of quantum mechanics which makes it general. It applies to arbitrary measurements on possibly multi-component Bose or Fermi gases in arbitrary initial quantum states, no matter how highly excited or far from equilibrium. We use an example to show how the results of two different and currently feasible experiments can be mapped onto each other by our spacetime transformation. DAMOP sorting category: 6.11 Nonlinear dynamics and out-of-equilibrium trapped gases EW acknowledge the financial support from the Alexander von Humboldt foundation.

On Nash Equilibrium and Evolutionarily Stable States That Are Not Characterised by the Folk Theorem

PubMed Central

Li, Jiawei; Kendall, Graham

2015-01-01

In evolutionary game theory, evolutionarily stable states are characterised by the folk theorem because exact solutions to the replicator equation are difficult to obtain. It is generally assumed that the folk theorem, which is the fundamental theory for non-cooperative games, defines all Nash equilibria in infinitely repeated games. Here, we prove that Nash equilibria that are not characterised by the folk theorem do exist. By adopting specific reactive strategies, a group of players can be better off by coordinating their actions in repeated games. We call it a type-k equilibrium when a group of k players coordinate their actions and they have no incentive to deviate from their strategies simultaneously. The existence and stability of the type-k equilibrium in general games is discussed. This study shows that the sets of Nash equilibria and evolutionarily stable states have greater cardinality than classic game theory has predicted in many repeated games. PMID:26288088

A Generalized Multi-Phase Framework for Modeling Cavitation in Cryogenic Fluids

NASA Technical Reports Server (NTRS)

Dorney, Dan (Technical Monitor); Hosangadi, Ashvin; Ahuja, Vineet

2003-01-01

A generalized multi-phase formulation for cavitation in fluids operating at temperatures elevated relative to their critical temperatures is presented. The thermal effects and the accompanying property variations due to phase change are modeled rigorously. Thermal equilibrium is assumed and fluid thermodynamic properties are specified along the saturation line using the NIST-12 databank. Fundamental changes in the physical characteristics of the cavity when thermal effects become pronounced are identified; the cavity becomes more porous, the interface less distinct, and has increased entrainment when temperature variations are present. Quantitative estimates of temperature and pressure depressions in both liquid nitrogen and liquid hydrogen were computed and compared with experimental data of Hord for hydrofoils. Excellent estimates of the leading edge temperature and pressure depression were obtained while the comparisons in the cavity closure region were reasonable. Liquid nitrogen cavities were consistently found to be in thermal equilibrium while liquid hydrogen cavities exhibited small, but distinct, non-equilibrium effects.

Generalized hydrodynamics and non-equilibrium steady states in integrable many-body quantum systems

NASA Astrophysics Data System (ADS)

Vasseur, Romain; Bulchandani, Vir; Karrasch, Christoph; Moore, Joel

The long-time dynamics of thermalizing many-body quantum systems can typically be described in terms of a conventional hydrodynamics picture that results from the decay of all but a few slow modes associated with standard conservation laws (such as particle number, energy, or momentum). However, hydrodynamics is expected to fail for integrable systems that are characterized by an infinite number of conservation laws, leading to unconventional transport properties and to complex non-equilibrium states beyond the traditional dogma of statistical mechanics. In this talk, I will describe recent attempts to understand such stationary states far from equilibrium using a generalized hydrodynamics picture. I will discuss the consistency of ``Bethe-Boltzmann'' kinetic equations with linear response Drude weights and with density-matrix renormalization group calculations. This work was supported by the Department of Energy through the Quantum Materials program (R. V.), NSF DMR-1206515, AFOSR MURI and a Simons Investigatorship (J. E. M.), DFG through the Emmy Noether program KA 3360/2-1 (C. K.).

Stability of differential susceptibility and infectivity epidemic models

PubMed Central

Bonzi, B.; Fall, A. A.; Iggidr, Abderrahman; Sallet, Gauthier

2011-01-01

We introduce classes of differential susceptibility and infectivity epidemic models. These models address the problem of flows between the different susceptible, infectious and infected compartments and differential death rates as well. We prove the global stability of the disease free equilibrium when the basic reproduction ratio ≤ 1 and the existence and uniqueness of an endemic equilibrium when > 1. We also prove the global asymptotic stability of the endemic equilibrium for a differential susceptibility and staged progression infectivity model, when > 1. Our results encompass and generalize those of [18, 22]. AMS Subject Classification : 34A34,34D23,34D40,92D30 PMID:20148330

Equilibrium figures inside the dark-matter ring and the shapes of elliptical galaxies

NASA Astrophysics Data System (ADS)

Kondratyev, B. P.; Trubitsyna, N. G.; Kireeva, E. N.

We solve the general problem of the theory of equilibrium figures and analyze two classes of liquid rotating gravitating figures residing inside a gravitating ring or torus. These figures form families of sequences of generalized oblate spheroids and triaxial ellipsoids, which at the lower limit of the tidal parameter α = 0 have the form of the Maclaurin spheroids and the Jacobi ellipsoids. In intermediate cases 0 < α ≤ αmax each new sequence of axisymmetric equilibrium figures has two non-rotating boundary spheroids. At the upper limit αmax/(π Gρ ) = 0.1867 the sequence degenerates into a single non-rotating spheroid with the eccentricity {e cr} ≈ 0.96 corresponding to the flattening limit of elliptical galaxies (E7). We also perform a detailed study of the sequences of generalized triaxial ellipsoids and find bifurcation points of triaxial ellipsoids in the sequences of generalized spheroids. We use this method to explain the shapes of E-galaxies. According to observations, very slowly rotating oblate E-type galaxies are known that have the shapes, which, because of instability, cannot be supported by velocity dispersion anisotropy exclusively. The hypothesis of a massive dark-matter outer ring requires no extreme anisotropy of pressure; it not only explains the shape of these elliptical galaxies, but also sheds new light on the riddle of the ellipticity limit (E7) of elliptical galaxies.

Influence of the extrinsic curvature on two-dimensional nematic films.

PubMed

Napoli, Gaetano; Vergori, Luigi

2018-05-01

Nematic films are thin fluid structures, ideally two dimensional, endowed with an in-plane degenerate nematic order. In this paper we examine a generalization of the classical Plateau problem to an axisymmetric nematic film bounded by two coaxial parallel rings. At equilibrium, the shape of the nematic film results from the competition between surface tension, which favors the minimization of the area, and the nematic elasticity, which instead promotes the alignment of the molecules along a common direction. We find two classes of equilibrium solutions in which the molecules are uniformly aligned along the meridians or parallels. Depending on two dimensionless parameters, one related to the geometry of the film and the other to the constitutive moduli, the Gaussian curvature of the equilibrium shape may be everywhere negative, vanishing, or positive. The stability of these equilibrium configurations is investigated.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivanov, A. A., E-mail: aai@a5.kiam.ru; Martynov, A. A., E-mail: martynov@a5.kiam.ru; Medvedev, S. Yu., E-mail: medvedev@a5.kiam.ru

In the MHD tokamak plasma theory, the plasma pressure is usually assumed to be isotropic. However, plasma heating by neutral beam injection and RF heating can lead to a strong anisotropy of plasma parameters and rotation of the plasma. The development of MHD equilibrium theory taking into account the plasma inertia and anisotropic pressure began a long time ago, but until now it has not been consistently applied in computational codes for engineering calculations of the plasma equilibrium and evolution in tokamak. This paper contains a detailed derivation of the axisymmetric plasma equilibrium equation in the most general form (withmore » arbitrary rotation and anisotropic pressure) and description of the specialized version of the SPIDER code. The original method of calculation of the equilibrium with an anisotropic pressure and a prescribed rotational transform profile is proposed. Examples of calculations and discussion of the results are also presented.« less

Coupling of Higgs and Leggett modes in non-equilibrium superconductors.

PubMed

Krull, H; Bittner, N; Uhrig, G S; Manske, D; Schnyder, A P

2016-06-21

In equilibrium systems amplitude and phase collective modes are decoupled, as they are mutually orthogonal excitations. The direct detection of these Higgs and Leggett collective modes by linear-response measurements is not possible, because they do not couple directly to the electromagnetic field. In this work, using numerical exact simulations we show for the case of two-gap superconductors, that optical pump-probe experiments excite both Higgs and Leggett modes out of equilibrium. We find that this non-adiabatic excitation process introduces a strong interaction between the collective modes, which is absent in equilibrium. Moreover, we propose a type of pump-probe experiment, which allows to probe and coherently control the Higgs and Leggett modes, and thus the order parameter directly. These findings go beyond two-band superconductors and apply to general collective modes in quantum materials.

Overshoot in biological systems modelled by Markov chains: a non-equilibrium dynamic phenomenon.

PubMed

Jia, Chen; Qian, Minping; Jiang, Daquan

2014-08-01

A number of biological systems can be modelled by Markov chains. Recently, there has been an increasing concern about when biological systems modelled by Markov chains will perform a dynamic phenomenon called overshoot. In this study, the authors found that the steady-state behaviour of the system will have a great effect on the occurrence of overshoot. They showed that overshoot in general cannot occur in systems that will finally approach an equilibrium steady state. They further classified overshoot into two types, named as simple overshoot and oscillating overshoot. They showed that except for extreme cases, oscillating overshoot will occur if the system is far from equilibrium. All these results clearly show that overshoot is a non-equilibrium dynamic phenomenon with energy consumption. In addition, the main result in this study is validated with real experimental data.

Influence of the extrinsic curvature on two-dimensional nematic films

NASA Astrophysics Data System (ADS)

Napoli, Gaetano; Vergori, Luigi

2018-05-01

Nematic films are thin fluid structures, ideally two dimensional, endowed with an in-plane degenerate nematic order. In this paper we examine a generalization of the classical Plateau problem to an axisymmetric nematic film bounded by two coaxial parallel rings. At equilibrium, the shape of the nematic film results from the competition between surface tension, which favors the minimization of the area, and the nematic elasticity, which instead promotes the alignment of the molecules along a common direction. We find two classes of equilibrium solutions in which the molecules are uniformly aligned along the meridians or parallels. Depending on two dimensionless parameters, one related to the geometry of the film and the other to the constitutive moduli, the Gaussian curvature of the equilibrium shape may be everywhere negative, vanishing, or positive. The stability of these equilibrium configurations is investigated.

Modelling the interaction between flooding events and economic growth

NASA Astrophysics Data System (ADS)

Grames, Johanna; Grass, Dieter; Prskawetz, Alexia; Blöschl, Günther

2015-04-01

Socio-hydrology describes the interaction between the socio-economy, water and population dynamics. Recent models analyze the interplay of community risk-coping culture, flooding damage and economic growth (Di Baldassarre, 2013, Viglione, 2014). These models descriptively explain the feedbacks between socio-economic development and natural disasters like floods. Contrary to these descriptive models, our approach develops an optimization model, where the intertemporal decision of an economic agent interacts with the hydrological system. This is the first economic growth model describing the interaction between the consumption and investment decisions of an economic agent and the occurrence of flooding events: Investments in defense capital can avoid floods even when the water level is high, but on the other hand such investment competes with investment in productive capital and hence may reduce the level of consumption. When floods occur, the flood damage therefore depends on the existing defense capital. The aim is to find an optimal tradeoff between investments in productive versus defense capital such as to optimize the stream of consumption in the long-term. We assume a non-autonomous exogenous periodic rainfall function (Yevjevich et.al. 1990, Zakaria 2001) which implies that the long-term equilibrium will be periodic . With our model we aim to derive mechanisms that allow consumption smoothing in the long term, and at the same time allow for optimal investment in flood defense to maximize economic output. We choose an aggregate welfare function that depends on the consumption level of the society as the objective function. I.e. we assume a social planer with perfect foresight that maximizes the aggregate welfare function. Within our model framework we can also study whether the path and level of defense capital (that protects people from floods) is related to the time preference rate of the social planner. Our model also allows to investigate how the frequency and the intensity of floods influence the investment behavior (i.e. the division between investing in productive versus defense capital).

Effect of helicity on the correlation time of large scales in turbulent flows

NASA Astrophysics Data System (ADS)

Cameron, Alexandre; Alexakis, Alexandros; Brachet, Marc-Étienne

2017-11-01

Solutions of the forced Navier-Stokes equation have been conjectured to thermalize at scales larger than the forcing scale, similar to an absolute equilibrium obtained for the spectrally truncated Euler equation. Using direct numeric simulations of Taylor-Green flows and general-periodic helical flows, we present results on the probability density function, energy spectrum, autocorrelation function, and correlation time that compare the two systems. In the case of highly helical flows, we derive an analytic expression describing the correlation time for the absolute equilibrium of helical flows that is different from the E-1 /2k-1 scaling law of weakly helical flows. This model predicts a new helicity-based scaling law for the correlation time as τ (k ) ˜H-1 /2k-1 /2 . This scaling law is verified in simulations of the truncated Euler equation. In simulations of the Navier-Stokes equations the large-scale modes of forced Taylor-Green symmetric flows (with zero total helicity and large separation of scales) follow the same properties as absolute equilibrium including a τ (k ) ˜E-1 /2k-1 scaling for the correlation time. General-periodic helical flows also show similarities between the two systems; however, the largest scales of the forced flows deviate from the absolute equilibrium solutions.

Rapid equilibrium sampling initiated from nonequilibrium data.

PubMed

Huang, Xuhui; Bowman, Gregory R; Bacallado, Sergio; Pande, Vijay S

2009-11-24

Simulating the conformational dynamics of biomolecules is extremely difficult due to the rugged nature of their free energy landscapes and multiple long-lived, or metastable, states. Generalized ensemble (GE) algorithms, which have become popular in recent years, attempt to facilitate crossing between states at low temperatures by inducing a random walk in temperature space. Enthalpic barriers may be crossed more easily at high temperatures; however, entropic barriers will become more significant. This poses a problem because the dominant barriers to conformational change are entropic for many biological systems, such as the short RNA hairpin studied here. We present a new efficient algorithm for conformational sampling, called the adaptive seeding method (ASM), which uses nonequilibrium GE simulations to identify the metastable states, and seeds short simulations at constant temperature from each of them to quantitatively determine their equilibrium populations. Thus, the ASM takes advantage of the broad sampling possible with GE algorithms but generally crosses entropic barriers more efficiently during the seeding simulations at low temperature. We show that only local equilibrium is necessary for ASM, so very short seeding simulations may be used. Moreover, the ASM may be used to recover equilibrium properties from existing datasets that failed to converge, and is well suited to running on modern computer clusters.

The hybrid delay task: Can capuchin monkeys (Cebus apella) sustain a delay after an initial choice to do so?

PubMed Central

Paglieri, Fabio; Focaroli, Valentina; Bramlett, Jessica; Tierno, Valeria; McIntyre, Joseph M.; Addessi, Elsa; Evans, Theodore A.; Beran, Michael J.

2013-01-01

Choosing to wait for a better outcome (delay choice) and sustaining the delay prior to that outcome (delay maintenance) are both prerequisites for successful self control in intertemporal choices. However, most existing experimental methods test these skills in isolation from each other, and no significant correlation has been observed in performance across these tasks. In this study we introduce a new paradigm, the hybrid delay task, which combines an initial delay choice with a subsequent delay maintenance stage. This allows testing how often choosing to wait is paired with the actual ability to do so. We tested 18 capuchin monkeys (Cebus apella) from two laboratories in various conditions, and we found that subjects frequently chose the delayed reward but then failed to wait for it, due to poor delay maintenance. However, performance improved with experience and different behavioral responses for error correction were evident. These findings have far reaching implications: if such a high error rate was observed also in other species (possibly including Homo sapiens), this may indicate that delay choice tasks that make use of salient, prepotent stimuli do not reliably assess generalized self control, insofar as choosing to wait does not entail always being able to do so. PMID:23274585

Willingness to pay and cost of illness for changes in health capital depreciation.

PubMed

Ried, W

1996-01-01

The paper investigates the relationship between the willingness to pay and the cost of illness approach with respect to the evaluation of economic burden due to adverse health effects. The basic intertemporal framework is provided by Grossman's pure investment model, while effects on individual morbidity are taken to be generated by marginal changes in the rate of health capital depreciation. More specifically, both the simple example of purely temporary changes and the more general case of persistent variations in health capital depreciation are discussed. The analysis generates two principal findings. First, for a class of identical individuals cost as measured by the cost of illness approach is demonstrated to provide a lower bound on the true welfare cost to the individual, i.e. cost as given by the willingness to pay approach. Moreover, the cost of illness is increasing in the size of the welfare loss. Second, if one takes into account the possible heterogeneity of individuals, a clear relationship between the cost values supplied by the two approaches no longer exists. As an example, the impact of variations in either financial wealth or health capital endowment is discussed. Thus, diversity in individual type turns out to blur the link between cost of illness and the true economic cost.

From density to interface fluctuations: The origin of wavelength dependence in surface tension

NASA Astrophysics Data System (ADS)

Hiester, Thorsten

2008-12-01

The height-height correlation function for a fluctuating interface between two coexisting bulk phases is derived by means of general equilibrium properties of the corresponding density-density correlation function. A wavelength-dependent surface tension γ(q) can be defined and expressed in terms of the direct correlation function c(r,r') , the equilibrium density profile ρ0(r) , and an operator which relates density to surface configurations. Neither the concept of an effective interface Hamiltonian nor the difference in pressure is needed to determine the general structure of the height-height correlations or γ(q) , respectively. This result generalizes the Mecke-Dietrich surface tension γMD(q) [Phys. Rev. E 59, 6766 (1999)] and modifies recently published criticism concerning γMD(q) [Tarazona, Checa, and Chacón, Phys. Rev. Lett. 99, 196101 (2007)].

Towards Microeconomic Resource Sharing in End System Multicast Networks Based on Walrasian General Equilibrium

NASA Astrophysics Data System (ADS)

Rezvani, Mohammad Hossein; Analoui, Morteza

2010-11-01

We have designed a competitive economical mechanism for application level multicast in which a number of independent services are provided to the end-users by a number of origin servers. Each offered service can be thought of as a commodity and the origin servers and the users who relay the service to their downstream nodes can thus be thought of as producers of the economy. Also, the end-users can be viewed as consumers of the economy. The proposed mechanism regulates the price of each service in such a way that general equilibrium holds. So, all allocations will be Pareto optimal in the sense that the social welfare of the users is maximized.

Taxation of exhaustible resources. [Monograph

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dasgupta, P.; Heal, G.; Stiglitz, J.

1980-01-01

This paper analyzes the effect of taxation on the intertemporal allocation of an exhaustible resource. A general framework within which a large variety of taxes can be analyzed is developed and then applied to a number of specific taxes. It is shown that there exists a pattern of taxation which can generate essentially any desired pattern of resource usage. Many tax policies, however, have effects markedly different both from the effects that these policies would have in the case of produced commodities and from those which they are designed (or widely thought) to have. For instance, if extraction costs aremore » zero, a depletion allowance at a constant rate (widely thought to encourage the extraction of resources) has absolutely no effect; its gradual removal (usually thought to be preferable to a sudden removal) leads to faster rates of depletion (and lower prices) now, but higher prices in the future; which its sudden and unanticipated removal has absolutely no distortionary effect on the pattern of extraction. More generally, it is shown that the effects of tax structure on the patterns of extraction are critically dependent on expectations concerning future taxation. The changes in tax structure that have occurred in the past fifty years are of the kind that, if they were anticipated, (or if similar further changes are expected to occur in the future) lead to excessively fast exploitation of natural resources. However, if it is believed that current tax policies (including rates) will persist indefinitely, the current tax structure would lead to excessive conservationism. Thus, whether in fact current tax policies have lead to excessive conservationism is a moot question.« less

Fate of polychlorinated biphenyls in a contaminated lake ecosystem: combining equilibrium passive sampling of sediment and water with total concentration measurements of biota.

PubMed

Mäenpää, Kimmo; Leppänen, Matti T; Figueiredo, Kaisa; Mayer, Philipp; Gilbert, Dorothea; Jahnke, Annika; Gil-Allué, Carmen; Akkanen, Jarkko; Nybom, Inna; Herve, Sirpa

2015-11-01

Equilibrium sampling devices can be applied to study and monitor the exposure and fate of hydrophobic organic chemicals on a thermodynamic basis. They can be used to determine freely dissolved concentrations and chemical activity ratios and to predict equilibrium partitioning concentrations of hydrophobic organic chemicals in biota lipids. The authors' aim was to assess the equilibrium status of polychlorinated biphenyls (PCBs) in a contaminated lake ecosystem and along its discharge course using equilibrium sampling devices for measurements in sediment and water and by also analyzing biota. The authors used equilibrium sampling devices (silicone rubber and polyethylene [PE]) to determine freely dissolved concentrations and chemical activities of PCBs in the water column and sediment porewater and calculated for both phases the corresponding equilibrium concentrations and chemical activities in model lipids. Overall, the studied ecosystem appeared to be in disequilibrium for the studied phases: sediment, water, and biota. Chemical activities of PCBs were higher in sediment than in water, which implies that the sediment functioned as a partitioning source of PCBs and that net diffusion occurred from the sediment to the water column. Measured lipid-normalized PCB concentrations in biota were generally below equilibrium lipid concentrations relative to the sediment (CLip ⇌Sed ) or water (CLip ⇌W ), indicating that PCB levels in the organisms were below the maximum partitioning levels. The present study shows the application versatility of equilibrium sampling devices in the field and facilitates a thermodynamic understanding of exposure and fate of PCBs in a contaminated lake and its discharge course. © 2015 SETAC.

A Maximal Element Theorem in FWC-Spaces and Its Applications

PubMed Central

Hu, Qingwen; Miao, Yulin

2014-01-01

A maximal element theorem is proved in finite weakly convex spaces (FWC-spaces, in short) which have no linear, convex, and topological structure. Using the maximal element theorem, we develop new existence theorems of solutions to variational relation problem, generalized equilibrium problem, equilibrium problem with lower and upper bounds, and minimax problem in FWC-spaces. The results represented in this paper unify and extend some known results in the literature. PMID:24782672

Thermodynamics of stoichiometric biochemical networks in living systems far from equilibrium.

PubMed

Qian, Hong; Beard, Daniel A

2005-04-22

The principles of thermodynamics apply to both equilibrium and nonequilibrium biochemical systems. The mathematical machinery of the classic thermodynamics, however, mainly applies to systems in equilibrium. We introduce a thermodynamic formalism for the study of metabolic biochemical reaction (open, nonlinear) networks in both time-dependent and time-independent nonequilibrium states. Classical concepts in equilibrium thermodynamics-enthalpy, entropy, and Gibbs free energy of biochemical reaction systems-are generalized to nonequilibrium settings. Chemical motive force, heat dissipation rate, and entropy production (creation) rate, key concepts in nonequilibrium systems, are introduced. Dynamic equations for the thermodynamic quantities are presented in terms of the key observables of a biochemical network: stoichiometric matrix Q, reaction fluxes J, and chemical potentials of species mu without evoking empirical rate laws. Energy conservation and the Second Law are established for steady-state and dynamic biochemical networks. The theory provides the physiochemical basis for analyzing large-scale metabolic networks in living organisms.

Evaporation in Capillary Porous Media at the Perfect Piston-Like Invasion Limit: Evidence of Nonlocal Equilibrium Effects

NASA Astrophysics Data System (ADS)

Attari Moghaddam, Alireza; Prat, Marc; Tsotsas, Evangelos; Kharaghani, Abdolreza

2017-12-01

The classical continuum modeling of evaporation in capillary porous media is revisited from pore network simulations of the evaporation process. The computed moisture diffusivity is characterized by a minimum corresponding to the transition between liquid and vapor transport mechanisms confirming previous interpretations. Also the study suggests an explanation for the scattering generally observed in the moisture diffusivity obtained from experimental data. The pore network simulations indicate a noticeable nonlocal equilibrium effect leading to a new interpretation of the vapor pressure-saturation relationship classically introduced to obtain the one-equation continuum model of evaporation. The latter should not be understood as a desorption isotherm as classically considered but rather as a signature of a nonlocal equilibrium effect. The main outcome of this study is therefore that nonlocal equilibrium two-equation model must be considered for improving the continuum modeling of evaporation.

Motility-Induced Phase Separation

NASA Astrophysics Data System (ADS)

Cates, Michael E.; Tailleur, Julien

2015-03-01

Self-propelled particles include both self-phoretic synthetic colloids and various microorganisms. By continually consuming energy, they bypass the laws of equilibrium thermodynamics. These laws enforce the Boltzmann distribution in thermal equilibrium: The steady state is then independent of kinetic parameters. In contrast, self-propelled particles tend to accumulate where they move more slowly. They may also slow down at high density for either biochemical or steric reasons. This creates positive feedback, which can lead to motility-induced phase separation (MIPS) between dense and dilute fluid phases. At leading order in gradients, a mapping relates variable-speed, self-propelled particles to passive particles with attractions. This deep link to equilibrium phase separation is confirmed by simulations but generally breaks down at higher order in gradients: New effects, with no equilibrium counterpart, then emerge. We give a selective overview of the fast-developing field of MIPS, focusing on theory and simulation but including a brief speculative survey of its experimental implications.

A comparative study of the adsorption equilibrium of progesterone by a carbon black and a commercial activated carbon

NASA Astrophysics Data System (ADS)

Valenzuela-Calahorro, Cristóbal; Navarrete-Guijosa, Antonio; Stitou, Mostafa; Cuerda-Correa, Eduardo M.

2007-04-01

In this paper the adsorption process of a natural steroid hormone (progesterone) by a carbon black and a commercial activated carbon has been studied. The corresponding equilibrium isotherms have been analyzed according to a previously proposed model which establishes a kinetic law satisfactorily fitting the C versus t isotherms. The analysis of the experimental data points out the existence of two well-defined sections in the equilibrium isotherms. A general equation including these two processes has been proposed, the global adsorption process being fitted to such equation. From the values of the kinetic equilibrium constant so obtained, values of standard average adsorption enthalpy ( ΔH°) and entropy ( ΔS°) have been calculated. Finally, information related to variations of differential adsorption enthalpy ( ΔH) and entropy ( ΔS) with the surface coverage fraction ( θ) was obtained by using the corresponding Clausius-Clapeyron equations.

METHOD FOR PUMPING GASES AT LOW VACUUM PRESSURES

DOEpatents

Milleron, N.

1962-06-01

A method is given for pumping overpressure "pulses" or "bursts" of gases without a significant rise in base pressure within a "gettering-type" vacuum pump having surfaces within the pumping cavity coated with or comprising clean gettering metal, e.g., Mo or Ta. The cavity is first pumped down by any convenient means to an equilibrium base pressure in the range desired, generally below 10/sup -6/ mm Hg. At this pressure, the metal immediately adsorbs overpressures or "bursts" of gases striking same with thermal motion without raising the base pressure significantiy. Desorption takes place at an equilibrium rate which, of course, is dependent upon the equilibrium pressure, and such desorbed gases are continuously removed by diffuaion pump or other pumping, whereby said overpressures or "bursts" of gases are removed without a rise in the equilibrium pressure and/or back diffusion of the gaseous pulse from the pumping cavity. (AEC)

Strong quantum solutions in conflicting-interest Bayesian games

NASA Astrophysics Data System (ADS)

Rai, Ashutosh; Paul, Goutam

2017-10-01

Quantum entanglement has been recently demonstrated as a useful resource in conflicting-interest games of incomplete information between two players, Alice and Bob [Pappa et al., Phys. Rev. Lett. 114, 020401 (2015), 10.1103/PhysRevLett.114.020401]. The general setting for such games is that of correlated strategies where the correlation between competing players is established through a trusted common adviser; however, players need not reveal their input to the adviser. So far, the quantum advantage in such games has been revealed in a restricted sense. Given a quantum correlated equilibrium strategy, one of the players can still receive a higher than quantum average payoff with some classically correlated equilibrium strategy. In this work, by considering a class of asymmetric Bayesian games, we show the existence of games with quantum correlated equilibrium where the average payoff of both the players exceeds the respective individual maximum for each player over all classically correlated equilibriums.

Energy flow in non-equilibrium conformal field theory

NASA Astrophysics Data System (ADS)

Bernard, Denis; Doyon, Benjamin

2012-09-01

We study the energy current and its fluctuations in quantum gapless 1d systems far from equilibrium modeled by conformal field theory, where two separated halves are prepared at distinct temperatures and glued together at a point contact. We prove that these systems converge towards steady states, and give a general description of such non-equilibrium steady states in terms of quantum field theory data. We compute the large deviation function, also called the full counting statistics, of energy transfer through the contact. These are universal and satisfy fluctuation relations. We provide a simple representation of these quantum fluctuations in terms of classical Poisson processes whose intensities are proportional to Boltzmann weights.

Minimal energy configurations of gravitationally interacting rigid bodies

NASA Astrophysics Data System (ADS)

Moeckel, Richard

2017-05-01

Consider a collection of n rigid, massive bodies interacting according to their mutual gravitational attraction. A relative equilibrium motion is one where the entire configuration rotates rigidly and uniformly about a fixed axis in R^3. Such a motion is possible only for special positions and orientations of the bodies. A minimal energy motion is one which has the minimum possible energy in its fixed angular momentum level. While every minimal energy motion is a relative equilibrium motion, the main result here is that a relative equilibrium motion of n≥3 disjoint rigid bodies is never an energy minimizer. This generalizes a known result about point masses to the case of rigid bodies.

AEDT: A new concept for ecological dynamics in the ever-changing world.

PubMed

Chesson, Peter

2017-05-01

The important concept of equilibrium has always been controversial in ecology, but a new, more general concept, an asymptotic environmentally determined trajectory (AEDT), overcomes many concerns with equilibrium by realistically incorporating long-term climate change while retaining much of the predictive power of a stable equilibrium. A population or ecological community is predicted to approach its AEDT, which is a function of time reflecting environmental history and biology. The AEDT invokes familiar questions and predictions but in a more realistic context in which consideration of past environments and a future changing profoundly due to human influence becomes possible. Strong applications are also predicted in population genetics, evolution, earth sciences, and economics.

Methane and carbon at equilibrium in source rocks

PubMed Central

2013-01-01

Methane in source rocks may not exist exclusively as free gas. It could exist in equilibrium with carbon and higher hydrocarbons: CH4 + C < = > Hydrocarbon. Three lines of evidence support this possibility. 1) Shales ingest gas in amounts and selectivities consistent with gas-carbon equilibrium. There is a 50% increase in solid hydrocarbon mass when Fayetteville Shale is exposed to methane (450 psi) under moderate conditions (100°C): Rock-Eval S2 (mg g-1) 8.5 = > 12.5. All light hydrocarbons are ingested, but with high selectivity, consistent with competitive addition to receptor sites in a growing polymer. Mowry Shale ingests butane vigorously from argon, for example, but not from methane under the same conditions. 2) Production data for a well producing from Fayetteville Shale declines along the theoretical curve for withdrawing gas from higher hydrocarbons in equilibrium with carbon. 3) A new general gas-solid equilibrium model accounts for natural gas at thermodynamic equilibrium, and C6-C7 hydrocarbons constrained to invariant compositions. The results make a strong case for methane in equilibrium with carbon and higher hydrocarbons. If correct, the higher hydrocarbons in source rocks are gas reservoirs, raising the possibility of substantially more gas in shales than analytically apparent, and far more gas in shale deposits than currently recognized. PMID:24330266

Non-equilibrium Quasi-Chemical Nucleation Model

NASA Astrophysics Data System (ADS)

Gorbachev, Yuriy E.

2018-04-01

Quasi-chemical model, which is widely used for nucleation description, is revised on the basis of recent results in studying of non-equilibrium effects in reacting gas mixtures (Kolesnichenko and Gorbachev in Appl Math Model 34:3778-3790, 2010; Shock Waves 23:635-648, 2013; Shock Waves 27:333-374, 2017). Non-equilibrium effects in chemical reactions are caused by the chemical reactions themselves and therefore these contributions should be taken into account in the corresponding expressions for reaction rates. Corrections to quasi-equilibrium reaction rates are of two types: (a) spatially homogeneous (caused by physical-chemical processes) and (b) spatially inhomogeneous (caused by gas expansion/compression processes and proportional to the velocity divergency). Both of these processes play an important role during the nucleation and are included into the proposed model. The method developed for solving the generalized Boltzmann equation for chemically reactive gases is applied for solving the set of equations of the revised quasi-chemical model. It is shown that non-equilibrium processes lead to essential deviation of the quasi-stationary distribution and therefore the nucleation rate from its traditional form.

Selfish routing equilibrium in stochastic traffic network: A probability-dominant description.

PubMed

Zhang, Wenyi; He, Zhengbing; Guan, Wei; Ma, Rui

2017-01-01

This paper suggests a probability-dominant user equilibrium (PdUE) model to describe the selfish routing equilibrium in a stochastic traffic network. At PdUE, travel demands are only assigned to the most dominant routes in the same origin-destination pair. A probability-dominant rerouting dynamic model is proposed to explain the behavioral mechanism of PdUE. To facilitate applications, the logit formula of PdUE is developed, of which a well-designed route set is not indispensable and the equivalent varitional inequality formation is simple. Two routing strategies, i.e., the probability-dominant strategy (PDS) and the dominant probability strategy (DPS), are discussed through a hypothetical experiment. It is found that, whether out of insurance or striving for perfection, PDS is a better choice than DPS. For more general cases, the conducted numerical tests lead to the same conclusion. These imply that PdUE (rather than the conventional stochastic user equilibrium) is a desirable selfish routing equilibrium for a stochastic network, given that the probability distributions of travel time are available to travelers.

Selfish routing equilibrium in stochastic traffic network: A probability-dominant description

PubMed Central

Zhang, Wenyi; Guan, Wei; Ma, Rui

2017-01-01

This paper suggests a probability-dominant user equilibrium (PdUE) model to describe the selfish routing equilibrium in a stochastic traffic network. At PdUE, travel demands are only assigned to the most dominant routes in the same origin-destination pair. A probability-dominant rerouting dynamic model is proposed to explain the behavioral mechanism of PdUE. To facilitate applications, the logit formula of PdUE is developed, of which a well-designed route set is not indispensable and the equivalent varitional inequality formation is simple. Two routing strategies, i.e., the probability-dominant strategy (PDS) and the dominant probability strategy (DPS), are discussed through a hypothetical experiment. It is found that, whether out of insurance or striving for perfection, PDS is a better choice than DPS. For more general cases, the conducted numerical tests lead to the same conclusion. These imply that PdUE (rather than the conventional stochastic user equilibrium) is a desirable selfish routing equilibrium for a stochastic network, given that the probability distributions of travel time are available to travelers. PMID:28829834

A new PIC noise reduction technique

NASA Astrophysics Data System (ADS)

Barnes, D. C.

2014-10-01

Numerical solution of the Vlasov equation is considered in a general situation in which there is an underlying static solution (equilibrium). There are no further assumptions about dimensionality, smallenss of orbits, or disparate time scales. The semi-characteristic (SC) method for Vlasov solution is described. The usual characteristics of the equation, which are the single particle orbits, are modified in such a way that the equilibrium phase-space flow is removed. In this way, the shot noise introduced by the usual discrete particle representation of the equilibrium is static in time and can be removed completely by subtraction. An almost exact algorithm for this is based on the observation that a (infinitesimal or) discrete time step of any equilibrium MC realization is again a realization of the equilibrium, building up strings of associated simulation particles. In this way, the only added discretization error arises from the need to extrapolate backward in time the chain end points one dt using a canonical transformation. Previously developed energy-conserving time-implicit methods are applied without modification. 1D ES examples of Landau damping and velocity-space instability are given to illustrate the method.

A Viscoelastic Constitutive Model Can Accurately Represent Entire Creep Indentation Tests of Human Patella Cartilage

PubMed Central

Pal, Saikat; Lindsey, Derek P.; Besier, Thor F.; Beaupre, Gary S.

2013-01-01

Cartilage material properties provide important insights into joint health, and cartilage material models are used in whole-joint finite element models. Although the biphasic model representing experimental creep indentation tests is commonly used to characterize cartilage, cartilage short-term response to loading is generally not characterized using the biphasic model. The purpose of this study was to determine the short-term and equilibrium material properties of human patella cartilage using a viscoelastic model representation of creep indentation tests. We performed 24 experimental creep indentation tests from 14 human patellar specimens ranging in age from 20 to 90 years (median age 61 years). We used a finite element model to reproduce the experimental tests and determined cartilage material properties from viscoelastic and biphasic representations of cartilage. The viscoelastic model consistently provided excellent representation of the short-term and equilibrium creep displacements. We determined initial elastic modulus, equilibrium elastic modulus, and equilibrium Poisson’s ratio using the viscoelastic model. The viscoelastic model can represent the short-term and equilibrium response of cartilage and may easily be implemented in whole-joint finite element models. PMID:23027200

Design and application of a technologically explicit hybrid energy-economy policy model with micro and macro economic dynamics

NASA Astrophysics Data System (ADS)

Bataille, Christopher G. F.

2005-11-01

Are further energy efficiency gains, or more recently greenhouse gas reductions, expensive or cheap? Analysts provide conflicting advice to policy makers based on divergent modelling perspectives, a 'top-down/bottom-up debate' in which economists use equation based models that equilibrate markets by maximizing consumer welfare, and technologists use technology simulation models that minimize the financial cost of providing energy services. This thesis summarizes a long term research project to find a middle ground between these two positions that is more useful to policy makers. Starting with the individual components of a behaviourally realistic and technologically explicit simulation model (ISTUM---Inter Sectoral Technology Use Model), or "hybrid", the individual sectors of the economy are linked using a framework of micro and macro economic feedbacks. These feedbacks are taken from the economic theory that informs the computable general equilibrium (CGE) family of models. Speaking in the languages of both economists and engineers, the resulting "physical" equilibrium model of Canada (CIMS---Canadian Integrated Modeling System), equilibrates energy and end-product markets, including imports and exports, for seven regions and 15 economic sectors, including primary industry, manufacturing, transportation, commerce, residences, governmental infrastructure and the energy supply sectors. Several different policy experiments demonstrate the value-added of the model and how its results compare to top-down and bottom-up practice. In general, the results show that technical adjustments make up about half the response to simulated energy policy, and macroeconomic demand adjustments the other half. Induced technical adjustments predominate with minor policies, while the importance of macroeconomic demand adjustment increases with the strength of the policy. Results are also shown for an experiment to derive estimates of future elasticity of substitution (ESUB) and autonomous energy efficiency indices (AEEI) from the model, parameters that could be used in long-run computable general equilibrium (CGE) analysis. The thesis concludes with a summary of the strengths and weakness of the new model as a policy tool, a work plan for its further improvement, and a discussion of the general potential for technologically explicit general equilibrium modelling.

Existence of equilibria in articulated bearings

NASA Astrophysics Data System (ADS)

Buscaglia, G.; Ciuperca, I.; Hafidi, I.; Jai, M.

2007-04-01

The existence of equilibrium solutions for a lubricated system consisting of an articulated body sliding over a flat plate is considered. Though this configuration is very common (it corresponds to the popular tilting-pad thrust bearings), the existence problem has only been addressed in extremely simplified cases, such as planar sliders of infinite width. Our results show the existence of at least one equilibrium for a quite general class of (nonplanar) slider shapes. We also extend previous results concerning planar sliders.

Equilibration and order in quantum Floquet matter

NASA Astrophysics Data System (ADS)

Moessner, R.; Sondhi, S. L.

2017-04-01

Equilibrium thermodynamics is characterized by two fundamental ideas: thermalization--that systems approach a late time thermal state; and phase structure--that thermal states exhibit singular changes as various parameters characterizing the system are changed. We summarize recent progress that has established generalizations of these ideas to periodically driven, or Floquet, closed quantum systems. This has resulted in the discovery of entirely new phases which exist only out of equilibrium, such as the π-spin glass/Floquet time crystal.

Integrable structure in discrete shell membrane theory

PubMed Central

Schief, W. K.

2014-01-01

We present natural discrete analogues of two integrable classes of shell membranes. By construction, these discrete shell membranes are in equilibrium with respect to suitably chosen internal stresses and external forces. The integrability of the underlying equilibrium equations is proved by relating the geometry of the discrete shell membranes to discrete O surface theory. We establish connections with generalized barycentric coordinates and nine-point centres and identify a discrete version of the classical Gauss equation of surface theory. PMID:24808755

Integrable structure in discrete shell membrane theory.

PubMed

Schief, W K

2014-05-08

We present natural discrete analogues of two integrable classes of shell membranes. By construction, these discrete shell membranes are in equilibrium with respect to suitably chosen internal stresses and external forces. The integrability of the underlying equilibrium equations is proved by relating the geometry of the discrete shell membranes to discrete O surface theory. We establish connections with generalized barycentric coordinates and nine-point centres and identify a discrete version of the classical Gauss equation of surface theory.

Quasi-Equilibrium States in the Tropics Simulated by a Cloud-Resolving Model. Part 1; Specific Features and Budget Analysis

NASA Technical Reports Server (NTRS)

Shie, C.-L.; Tao, W.-K.; Simpson, J.; Sui, C.-H.; Starr, David OC. (Technical Monitor)

2001-01-01

A series of long-term integrations using the two-dimensional Goddard Cumulus Ensemble (GCE) model were performed by altering imposed environmental components to produce various quasi-equilibrium thermodynamic states. Model results show that the genesis of a warm/wet quasi-equilibrium state is mainly due to either strong vertical wind shear (from nudging) or large surface fluxes (from strong surface winds), while a cold/dry quasi-equilibrium state is attributed to a remarkably weakened mixed-wind shear (from vertical mixing due to deep convection) along with weak surface winds. In general, latent heat flux and net large-scale temperature forcing, the two dominant physical processes, dominate in the beginning stage of the simulated convective systems, then considerably weaken in the final stage, which leads to quasi-equilibrium states. A higher thermodynamic regime is found to produce a larger rainfall amount, as convective clouds are the leading source of rainfall over stratiform clouds even though the former occupy much less area. Moreover, convective clouds are more likely to occur in the presence of strong surface winds (latent heat flux), while stratiform clouds (especially the well-organized type) are favored in conditions with strong wind shear (large-scale forcing). The convective systems, which consist of distinct cloud types due to the variation in horizontal winds, are also found to propagate differently. Accordingly, convective systems with mixed-wind shear generally propagate in the direction of shear, while the system with strong (multidirectional) wind shear propagates in a more complex way. Based on the results from the temperature (Q1) and moisture (Q2) budgets, cloud-scale eddies are found to act as a hydrodynamic 'vehicle' that cascades the heat and moisture vertically. Several other specific features such as atmospheric stability, CAPE, and mass fluxes are also investigated and found to be significantly different between diverse quasi-equilibrium states. Detailed comparisons between the various states are presented.

CET89 - CHEMICAL EQUILIBRIUM WITH TRANSPORT PROPERTIES, 1989

NASA Technical Reports Server (NTRS)

Mcbride, B.

1994-01-01

Scientists and engineers need chemical equilibrium composition data to calculate the theoretical thermodynamic properties of a chemical system. This information is essential in the design and analysis of equipment such as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical processing equipment. The substantial amount of numerical computation required to obtain equilibrium compositions and transport properties for complex chemical systems led scientists at NASA's Lewis Research Center to develop CET89, a program designed to calculate the thermodynamic and transport properties of these systems. CET89 is a general program which will calculate chemical equilibrium compositions and mixture properties for any chemical system with available thermodynamic data. Generally, mixtures may include condensed and gaseous products. CET89 performs the following operations: it 1) obtains chemical equilibrium compositions for assigned thermodynamic states, 2) calculates dilute-gas transport properties of complex chemical mixtures, 3) obtains Chapman-Jouguet detonation properties for gaseous species, 4) calculates incident and reflected shock properties in terms of assigned velocities, and 5) calculates theoretical rocket performance for both equilibrium and frozen compositions during expansion. The rocket performance function allows the option of assuming either a finite area or an infinite area combustor. CET89 accommodates problems involving up to 24 reactants, 20 elements, and 600 products (400 of which may be condensed). The program includes a library of thermodynamic and transport properties in the form of least squares coefficients for possible reaction products. It includes thermodynamic data for over 1300 gaseous and condensed species and transport data for 151 gases. The subroutines UTHERM and UTRAN convert thermodynamic and transport data to unformatted form for faster processing. The program conforms to the FORTRAN 77 standard, except for some input in NAMELIST format. It requires about 423 KB memory, and is designed to be used on mainframe, workstation, and mini computers. Due to its memory requirements, this program does not readily lend itself to implementation on MS-DOS based machines.

Motion in a modified Chermnykh's restricted three-body problem with oblateness

NASA Astrophysics Data System (ADS)

Singh, Jagadish; Leke, Oni

2014-03-01

In this paper, the restricted problem of three bodies is generalized to include a case when the passively gravitating test particle is an oblate spheroid under effect of small perturbations in the Coriolis and centrifugal forces when the first primary is a source of radiation and the second one an oblate spheroid, coupled with the influence of the gravitational potential from the belt. The equilibrium points are found and it is seen that, in addition to the usual three collinear equilibrium points, there appear two new ones due to the potential from the belt and the mass ratio. Two triangular equilibrium points exist. These equilibria are affected by radiation of the first primary, small perturbation in the centrifugal force, oblateness of both the test particle and second primary and the effect arising from the mass of the belt. The linear stability of the equilibrium points is explored and the stability outcome of the collinear equilibrium points remains unstable. In the case of the triangular points, motion is stable with respect to some conditions which depend on the critical mass parameter; influenced by the small perturbations, radiating effect of the first primary, oblateness of the test body and second primary and the gravitational potential from the belt. The effects of each of the imposed free parameters are analyzed. The potential from the belt and small perturbation in the Coriolis force are stabilizing parameters while radiation, small perturbation in the centrifugal force and oblateness reduce the stable regions. The overall effect is that the region of stable motion increases under the combine action of these parameters. We have also found the frequencies of the long and short periodic motion around stable triangular points. Illustrative numerical exploration is rendered in the Sun-Jupiter and Sun-Earth systems where we show that in reality, for some values of the system parameters, the additional equilibrium points do not in general exist even when there is a belt to interact with.

A Fuzzy Approach of the Competition on the Air Transport Market

NASA Technical Reports Server (NTRS)

Charfeddine, Souhir; DeColigny, Marc; Camino, Felix Mora; Cosenza, Carlos Alberto Nunes

2003-01-01

The aim of this communication is to study with a new scope the conditions of the equilibrium in an air transport market where two competitive airlines are operating. Each airline is supposed to adopt a strategy maximizing its profit while its estimation of the demand has a fuzzy nature. This leads each company to optimize a program of its proposed services (frequency of the flights and ticket prices) characterized by some fuzzy parameters. The case of monopoly is being taken as a benchmark. Classical convex optimization can be used to solve this decision problem. This approach provides the airline with a new decision tool where uncertainty can be taken into account explicitly. The confrontation of the strategies of the companies, in the ease of duopoly, leads to the definition of a fuzzy equilibrium. This concept of fuzzy equilibrium is more general and can be applied to several other domains. The formulation of the optimization problem and the methodological consideration adopted for its resolution are presented in their general theoretical aspect. In the case of air transportation, where the conditions of management of operations are critical, this approach should offer to the manager elements needed to the consolidation of its decisions depending on the circumstances (ordinary, exceptional events,..) and to be prepared to face all possibilities. Keywords: air transportation, competition equilibrium, convex optimization , fuzzy modeling,

Prediction of chemical speciation in stabilized/solidified wastes using a general chemical equilibrium model. Part 1: Chemical representation of cementitious binders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, J.Y.; Batchelor, B.

1999-03-01

Chemical equilibrium models are useful to evaluate stabilized/solidified waste. A general equilibrium model, SOLTEQ, a modified version of MINTEQA2 for S/S, was applied to predict the chemical speciations in the stabilized/solidified waste form. A method was developed to prepare SOLTEQ input data that can chemically represent various stabilized/solidified binders. Taylor`s empirical model was used to describe partitioning of alkali ions. As a result, SOLTEQ could represent chemical speciation in pure binder systems such as ordinary Portland cement and ordinary Portland cement + fly ash. Moreover, SOLTEQ could reasonably describe the effects on the chemical speciation due to variations in water-to-cement,more » fly ash contents, and hydration times of various binder systems. However, this application of SOLTEQ was not accurate in predicting concentrations of Ca, Si, and SO{sub 4} ions, due to uncertainties in the CSH solubility model and K{sub sp} values of cement hydrates at high pH values.« less

The Markov process admits a consistent steady-state thermodynamic formalism

NASA Astrophysics Data System (ADS)

Peng, Liangrong; Zhu, Yi; Hong, Liu

2018-01-01

The search for a unified formulation for describing various non-equilibrium processes is a central task of modern non-equilibrium thermodynamics. In this paper, a novel steady-state thermodynamic formalism was established for general Markov processes described by the Chapman-Kolmogorov equation. Furthermore, corresponding formalisms of steady-state thermodynamics for the master equation and Fokker-Planck equation could be rigorously derived in mathematics. To be concrete, we proved that (1) in the limit of continuous time, the steady-state thermodynamic formalism for the Chapman-Kolmogorov equation fully agrees with that for the master equation; (2) a similar one-to-one correspondence could be established rigorously between the master equation and Fokker-Planck equation in the limit of large system size; (3) when a Markov process is restrained to one-step jump, the steady-state thermodynamic formalism for the Fokker-Planck equation with discrete state variables also goes to that for master equations, as the discretization step gets smaller and smaller. Our analysis indicated that general Markov processes admit a unified and self-consistent non-equilibrium steady-state thermodynamic formalism, regardless of underlying detailed models.

Onset of fast "ideal" tearing in thin current sheets: Dependence on the equilibrium current profile

NASA Astrophysics Data System (ADS)

Pucci, F.; Velli, M.; Tenerani, A.; Del Sarto, D.

2018-03-01

In this paper, we study the scaling relations for the triggering of the fast, or "ideal," tearing instability starting from equilibrium configurations relevant to astrophysical as well as laboratory plasmas that differ from the simple Harris current sheet configuration. We present the linear tearing instability analysis for equilibrium magnetic fields which (a) go to zero at the boundary of the domain and (b) contain a double current sheet system (the latter previously studied as a Cartesian proxy for the m = 1 kink mode in cylindrical plasmas). More generally, we discuss the critical aspect ratio scalings at which the growth rates become independent of the Lundquist number S, in terms of the dependence of the Δ' parameter on the wavenumber k of unstable modes. The scaling Δ'(k) with k at small k is found to categorize different equilibria broadly: the critical aspect ratios may be even smaller than L/a ˜ Sα with α = 1/3 originally found for the Harris current sheet, but there exists a general lower bound α ≥ 1/4.

Surface thermodynamics, surface stress, equations at surfaces and triple lines for deformable bodies.

PubMed

Olives, Juan

2010-03-03

The thermodynamics and mechanics of the surface of a deformable body are studied here, following and refining the general approach of Gibbs. It is first shown that the 'local' thermodynamic variables of the state of the surface are only the temperature, the chemical potentials and the surface strain tensor (true thermodynamic variables, for a viscoelastic solid or a viscous fluid). A new definition of the surface stress is given and the corresponding surface thermodynamics equations are presented. The mechanical equilibrium equation at the surface is then obtained. It involves the surface stress and is similar to the Cauchy equation for the volume. Its normal component is a generalization of the Laplace equation. At a (body-fluid-fluid) triple contact line, two equations are obtained, which represent: (i) the equilibrium of the forces (surface stresses) for a triple line fixed on the body; (ii) the equilibrium relative to the motion of the line with respect to the body. This last equation leads to a strong modification of Young's classical capillary equation.

Introduction of Differential Scanning Calorimetry in a General Chemistry Laboratory Course: Determination of Heat Capacity of Metals and Demonstration of Law of Dulong and Petit

ERIC Educational Resources Information Center

D'Amelia, Ronald P.; Stracuzzi, Vincent; Nirode, William F.

2008-01-01

Today's general chemistry students are introduced to many of the principles and concepts of thermodynamics. In first-year general chemistry undergraduate courses, thermodynamic properties such as heat capacity are frequently discussed. Classical calorimetric methods of analysis and thermal equilibrium experiments are used to determine heat…

Econometrics and data of the 9 sector Dynamic General Equilibrium Model. Volume III. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berndt, E.R.; Fraumeni, B.M.; Hudson, E.A.

1981-03-01

This report presents the econometrics and data of the 9 sector Dynamic General Equilibrium Model. There are two key components of 9DGEM - the model of household behavior and the model of produconcrneer behavior. The household model is concerned with decisions on consumption, saving, labor supply and the composition of consumption. The producer model is concerned with output price formation and determination of input patterns and purchases for each of the nine producing sectors. These components form the behavioral basis of DGEM. The remaining components are concerned with constraints, balance conditions, accounting, and government revenues and expenditures (these elements aremore » developed in the report on the model specification).« less

Application of the equilibrium spin technique to a typical low-wing general aviation design

NASA Technical Reports Server (NTRS)

Tischler, M. B.; Barlow, J. B.

1979-01-01

A graphical implementation of the equilibrium technique for obtaining spin modes from rotary balance data is presented. Using this technique, spin modes were computed for the NASA Low-Wing General Aviation Aircraft. The computed angles of attack are within 10 degrees of the NASA spin tunnel results. The method also provides information on the dynamic nature of spin modes. This technique offers the capability of providing a great deal of information on spin modes and recovery, using data from a single experimental installation. Such a technique could be utilized in the preliminary design phase in order to provide basic information on aircraft spin and recovery characteristics. Results, advantages and limitations of the application of this technique are discussed.

Estimated Performance of Radial-Flow Exit Nozzles for Air in Chemical Equilibrium

NASA Technical Reports Server (NTRS)

Englert, Gerald W.; Kochendorfer, Fred D.

1959-01-01

The thrust, boundary-layer, and heat-transfer characteristics were computed for nozzles having radial flow in the divergent part. The working medium was air in chemical equilibrium, and the boundary layer was assumed to be all turbulent. Stagnation pressure was varied from 1 to 32 atmospheres, stagnation temperature from 1000 to 6000 R, and wall temperature from 1000 to 3000 R. Design pressure ratio was varied from 5 to 320, and operating pressure ratio was varied from 0.25 to 8 times the design pressure ratio. Results were generalized independent of divergence angle and were also generalized independent of stagnation pressure in the temperature range of 1000 to 3000 R. A means of determining the aerodynamically optimum wall angle is provided.

Energy Efficiency and Renewables: Market and Behavioral Failures

ScienceCinema

James Sweeney

2017-12-09

Thursday, January 28, 2010: Policies to promote renewable energy and energy efficiency have been gaining momentum throughout the world, often justified by environmental and energy security concerns. This presentation first talks about energy efficiency options, then delves into the economic motivation for energy efficiency and renewable energy policies by articulating the classes of relevant behavioral failures and market failures. Such behavioral and market failures may vary intertemporally or atemporally; the temporal structure and the extent of the failures are the critical considerations in the development of energy policies. The talk discusses key policy instruments and assess the extent to which they are well-suited to correct for failures with different structures. http://eetd.lbl.gov/dls/lecture-01-28...

Is the Rational Addiction model inherently impossible to estimate?

PubMed

Laporte, Audrey; Dass, Adrian Rohit; Ferguson, Brian S

2017-07-01

The Rational Addiction (RA) model is increasingly often estimated using individual level panel data with mixed results; in particular, with regard to the implied rate of time discount. This paper suggests that the odd values of the rate of discount frequently found in the literature may in fact be a consequence of the saddle-point dynamics associated with individual level inter-temporal optimization problems. We report the results of Monte Carlo experiments estimating RA-type difference equations that seem to suggest the possibility that the presence of both a stable and an unstable root in the dynamic process may create serious problems for the estimation of RA equations. Copyright © 2016 Elsevier B.V. All rights reserved.

Discount rates and the education gradient in mammography in the UK.

PubMed

Bíró, Anikó

2013-09-01

I analyse intertemporal decisions on undertaking breast cancer screening by women aged 50-64  years in the UK and provide estimates of the rate of discounting potential future benefits of screening. I also analyse education differences in mammography decisions and examine the underlying mechanisms by which education influences breast cancer screening attendance. I estimate a structural model, which reveals that although there are differences in the disutility of breast cancer screening between education groups, there is no difference in the estimated discount factor. These results suggest that the observed education gradient is mainly due to differences in health behaviours and healthcare attitudes. Copyright © 2013 John Wiley & Sons, Ltd.

The volatility of stock market prices.

PubMed

Shiller, R J

1987-01-02

If the volatility of stock market prices is to be understood in terms of the efficient markets hypothesis, then there should be evidence that true investment value changes through time sufficiently to justify the price changes. Three indicators of change in true investment value of the aggregate stock market in the United States from 1871 to 1986 are considered: changes in dividends, in real interest rates, and in a direct measure of intertemporal marginal rates of substitution. Although there are some ambiguities in interpreting the evidence, dividend changes appear to contribute very little toward justifying the observed historical volatility of stock prices. The other indicators contribute some, but still most of the volatility of stock market prices appears unexplained.

Chemical bonding and the equilibrium composition of Grignard reagents in ethereal solutions.

PubMed

Henriques, André M; Barbosa, André G H

2011-11-10

A thorough analysis of the electronic structure and thermodynamic aspects of Grignard reagents and its associated equilibrium composition in ethereal solutions is performed. Considering methylmagnesium halides containing fluorine, chlorine, and bromine, we studied the neutral, charged, and radical species associated with their chemical equilibrium in solution. The ethereal solvents considered, tetrahydrofuran (THF) and ethyl ether (Et(2)O), were modeled using the polarizable continuum model (PCM) and also by explicit coordination to the Mg atoms in a cluster. The chemical bonding of the species that constitute the Grignard reagent is analyzed in detail with generalized valence bond (GVB) wave functions. Equilibrium constants were calculated with the DFT/M06 functional and GVB wave functions, yielding similar results. According to our calculations and existing kinetic and electrochemical evidence, the species R(•), R(-), (•)MgX, and RMgX(2)(-) must be present in low concentration in the equilibrium. We conclude that depending on the halogen, a different route must be followed to produce the relevant equilibrium species in each case. Chloride and bromide must preferably follow a "radical-based" pathway, and fluoride must follow a "carbanionic-based" pathway. These different mechanisms are contrasted against the available experimental results and are proven to be consistent with the existing thermodynamic data on the Grignard reagent equilibria.

A reaction-based paradigm to model reactive chemical transport in groundwater with general kinetic and equilibrium reactions.

PubMed

Zhang, Fan; Yeh, Gour-Tsyh; Parker, Jack C; Brooks, Scott C; Pace, Molly N; Kim, Young-Jin; Jardine, Philip M; Watson, David B

2007-06-16

This paper presents a reaction-based water quality transport model in subsurface flow systems. Transport of chemical species with a variety of chemical and physical processes is mathematically described by M partial differential equations (PDEs). Decomposition via Gauss-Jordan column reduction of the reaction network transforms M species reactive transport equations into two sets of equations: a set of thermodynamic equilibrium equations representing N(E) equilibrium reactions and a set of reactive transport equations of M-N(E) kinetic-variables involving no equilibrium reactions (a kinetic-variable is a linear combination of species). The elimination of equilibrium reactions from reactive transport equations allows robust and efficient numerical integration. The model solves the PDEs of kinetic-variables rather than individual chemical species, which reduces the number of reactive transport equations and simplifies the reaction terms in the equations. A variety of numerical methods are investigated for solving the coupled transport and reaction equations. Simulation comparisons with exact solutions were performed to verify numerical accuracy and assess the effectiveness of various numerical strategies to deal with different application circumstances. Two validation examples involving simulations of uranium transport in soil columns are presented to evaluate the ability of the model to simulate reactive transport with complex reaction networks involving both kinetic and equilibrium reactions.

Comparison of DNA decatenation by Escherichia coli topoisomerase IV and topoisomerase III: implications for non-equilibrium topology simplification

PubMed Central

Seol, Yeonee; Hardin, Ashley H.; Strub, Marie-Paule; Charvin, Gilles; Neuman, Keir C.

2013-01-01

Type II topoisomerases are essential enzymes that regulate DNA topology through a strand-passage mechanism. Some type II topoisomerases relax supercoils, unknot and decatenate DNA to below thermodynamic equilibrium. Several models of this non-equilibrium topology simplification phenomenon have been proposed. The kinetic proofreading (KPR) model postulates that strand passage requires a DNA-bound topoisomerase to collide twice in rapid succession with a second DNA segment, implying a quadratic relationship between DNA collision frequency and relaxation rate. To test this model, we used a single-molecule assay to measure the unlinking rate as a function of DNA collision frequency for Escherichia coli topoisomerase IV (topo IV) that displays efficient non-equilibrium topology simplification activity, and for E. coli topoisomerase III (topo III), a type IA topoisomerase that unlinks and unknots DNA to equilibrium levels. Contrary to the predictions of the KPR model, topo IV and topo III unlinking rates were linearly related to the DNA collision frequency. Furthermore, topo III exhibited decatenation activity comparable with that of topo IV, supporting proposed roles for topo III in DNA segregation. This study enables us to rule out the KPR model for non-equilibrium topology simplification. More generally, we establish an experimental approach to systematically control DNA collision frequency. PMID:23460205

Thermodynamic Bethe ansatz for non-equilibrium steady states: exact energy current and fluctuations in integrable QFT

NASA Astrophysics Data System (ADS)

Castro-Alvaredo, Olalla; Chen, Yixiong; Doyon, Benjamin; Hoogeveen, Marianne

2014-03-01

We evaluate the exact energy current and scaled cumulant generating function (related to the large-deviation function) in non-equilibrium steady states with energy flow, in any integrable model of relativistic quantum field theory (IQFT) with diagonal scattering. Our derivations are based on various recent results of Bernard and Doyon. The steady states are built by connecting homogeneously two infinite halves of the system thermalized at different temperatures Tl, Tr, and waiting for a long time. We evaluate the current J(Tl, Tr) using the exact QFT density matrix describing these non-equilibrium steady states and using Zamolodchikov’s method of the thermodynamic Bethe ansatz (TBA). The scaled cumulant generating function is obtained from the extended fluctuation relations which hold in integrable models. We verify our formula in particular by showing that the conformal field theory (CFT) result is obtained in the high-temperature limit. We analyze numerically our non-equilibrium steady-state TBA equations for three models: the sinh-Gordon model, the roaming trajectories model, and the sine-Gordon model at a particular reflectionless point. Based on the numerics, we conjecture that an infinite family of non-equilibrium c-functions, associated with the scaled cumulants, can be defined, which we interpret physically. We study the full scaled distribution function and find that it can be described by a set of independent Poisson processes. Finally, we show that the ‘additivity’ property of the current, which is known to hold in CFT and was proposed to hold more generally, does not hold in general IQFT—that is, J(Tl, Tr) is not of the form f(Tl) - f(Tr).

Variational Koopman models: Slow collective variables and molecular kinetics from short off-equilibrium simulations

NASA Astrophysics Data System (ADS)

Wu, Hao; Nüske, Feliks; Paul, Fabian; Klus, Stefan; Koltai, Péter; Noé, Frank

2017-04-01

Markov state models (MSMs) and master equation models are popular approaches to approximate molecular kinetics, equilibria, metastable states, and reaction coordinates in terms of a state space discretization usually obtained by clustering. Recently, a powerful generalization of MSMs has been introduced, the variational approach conformation dynamics/molecular kinetics (VAC) and its special case the time-lagged independent component analysis (TICA), which allow us to approximate slow collective variables and molecular kinetics by linear combinations of smooth basis functions or order parameters. While it is known how to estimate MSMs from trajectories whose starting points are not sampled from an equilibrium ensemble, this has not yet been the case for TICA and the VAC. Previous estimates from short trajectories have been strongly biased and thus not variationally optimal. Here, we employ the Koopman operator theory and the ideas from dynamic mode decomposition to extend the VAC and TICA to non-equilibrium data. The main insight is that the VAC and TICA provide a coefficient matrix that we call Koopman model, as it approximates the underlying dynamical (Koopman) operator in conjunction with the basis set used. This Koopman model can be used to compute a stationary vector to reweight the data to equilibrium. From such a Koopman-reweighted sample, equilibrium expectation values and variationally optimal reversible Koopman models can be constructed even with short simulations. The Koopman model can be used to propagate densities, and its eigenvalue decomposition provides estimates of relaxation time scales and slow collective variables for dimension reduction. Koopman models are generalizations of Markov state models, TICA, and the linear VAC and allow molecular kinetics to be described without a cluster discretization.

On the dynamics aspects for the plane motion of a particle under the action of potential forces in the presence of a magnetic field

NASA Astrophysics Data System (ADS)

Mnasri, C.; Elmandouh, A. A.

2018-06-01

This article deals with the general motion of a particle moving in the Euclidean plane under the influence of a conservative potential force in the presence of a magnetic field perpendicular to the plane of the motion. We introduce the conditions for which this motion is not algebraically integrable by using Kowalevski's exponents. We present the equilibrium positions and study their stability and moreover, we clarify that the existence of the magnetic field acts as a stabilizer for maximum unstable equilibrium points for the effective potential. We employ Lyapunov theorem to construct the periodic solutions near the equilibrium points. The allowed regions of motion are specified and illustrated graphically.

Universal ideal behavior and macroscopic work relation of linear irreversible stochastic thermodynamics

NASA Astrophysics Data System (ADS)

Ma, Yi-An; Qian, Hong

2015-06-01

We revisit the Ornstein-Uhlenbeck (OU) process as the fundamental mathematical description of linear irreversible phenomena, with fluctuations, near an equilibrium. By identifying the underlying circulating dynamics in a stationary process as the natural generalization of classical conservative mechanics, a bridge between a family of OU processes with equilibrium fluctuations and thermodynamics is established through the celebrated Helmholtz theorem. The Helmholtz theorem provides an emergent macroscopic ‘equation of state’ of the entire system, which exhibits a universal ideal thermodynamic behavior. Fluctuating macroscopic quantities are studied from the stochastic thermodynamic point of view and a non-equilibrium work relation is obtained in the macroscopic picture, which may facilitate experimental study and application of the equalities due to Jarzynski, Crooks, and Hatano and Sasa.

Fugacity and concentration gradients in a gravity field

NASA Technical Reports Server (NTRS)

May, C. E.

1986-01-01

Equations are reviewed which show that at equilibrium fugacity and concentration gradients can exist in gravitational fields. At equilibrium, the logarithm of the ratio of the fugacities of a species at two different locations in a gravitational field is proportional to the difference in the heights of the two locations and the molecular weight of the species. An analogous relation holds for the concentration ratios in a multicomponent system. The ratio is calculated for a variety of examples. The kinetics for the general process are derived, and the time required to approach equilibrium is calculated for several systems. The following special topics are discussed: ionic solutions, polymers, multiphase systems, hydrostatic pressure, osmotic pressure, and solubility gradients in a gravity field.

Computer model of one-dimensional equilibrium controlled sorption processes

USGS Publications Warehouse

Grove, D.B.; Stollenwerk, K.G.

1984-01-01

A numerical solution to the one-dimensional solute-transport equation with equilibrium-controlled sorption and a first-order irreversible-rate reaction is presented. The computer code is written in FORTRAN language, with a variety of options for input and output for user ease. Sorption reactions include Langmuir, Freundlich, and ion-exchange, with or without equal valance. General equations describing transport and reaction processes are solved by finite-difference methods, with nonlinearities accounted for by iteration. Complete documentation of the code, with examples, is included. (USGS)

Non-equilibrium STLS approach to transport properties of single impurity Anderson model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rezai, Raheleh, E-mail: R_Rezai@sbu.ac.ir; Ebrahimi, Farshad, E-mail: Ebrahimi@sbu.ac.ir

In this work, using the non-equilibrium Keldysh formalism, we study the effects of the electron–electron interaction and the electron-spin correlation on the non-equilibrium Kondo effect and the transport properties of the symmetric single impurity Anderson model (SIAM) at zero temperature by generalizing the self-consistent method of Singwi, Tosi, Land, and Sjolander (STLS) for a single-band tight-binding model with Hubbard type interaction to out of equilibrium steady-states. We at first determine in a self-consistent manner the non-equilibrium spin correlation function, the effective Hubbard interaction, and the double-occupancy at the impurity site. Then, using the non-equilibrium STLS spin polarization function in themore » non-equilibrium formalism of the iterative perturbation theory (IPT) of Yosida and Yamada, and Horvatic and Zlatic, we compute the spectral density, the current–voltage characteristics and the differential conductance as functions of the applied bias and the strength of on-site Hubbard interaction. We compare our spectral densities at zero bias with the results of numerical renormalization group (NRG) and depict the effects of the electron–electron interaction and electron-spin correlation at the impurity site on the aforementioned properties by comparing our numerical result with the order U{sup 2} IPT. Finally, we show that the obtained numerical results on the differential conductance have a quadratic universal scaling behavior and the resulting Kondo temperature shows an exponential behavior. -- Highlights: •We introduce for the first time the non-equilibrium method of STLS for Hubbard type models. •We determine the transport properties of SIAM using the non-equilibrium STLS method. •We compare our results with order-U2 IPT and NRG. •We show that non-equilibrium STLS, contrary to the GW and self-consistent RPA, produces the two Hubbard peaks in DOS. •We show that the method keeps the universal scaling behavior and correct exponential behavior of Kondo temperature.« less

Pharmaceutical industry and trade liberalization using computable general equilibrium model.

PubMed

Barouni, M; Ghaderi, H; Banouei, Aa

2012-01-01

Computable general equilibrium models are known as a powerful instrument in economic analyses and widely have been used in order to evaluate trade liberalization effects. The purpose of this study was to provide the impacts of trade openness on pharmaceutical industry using CGE model. Using a computable general equilibrium model in this study, the effects of decrease in tariffs as a symbol of trade liberalization on key variables of Iranian pharmaceutical products were studied. Simulation was performed via two scenarios in this study. The first scenario was the effect of decrease in tariffs of pharmaceutical products as 10, 30, 50, and 100 on key drug variables, and the second was the effect of decrease in other sectors except pharmaceutical products on vital and economic variables of pharmaceutical products. The required data were obtained and the model parameters were calibrated according to the social accounting matrix of Iran in 2006. The results associated with simulation demonstrated that the first scenario has increased import, export, drug supply to markets and household consumption, while import, export, supply of product to market, and household consumption of pharmaceutical products would averagely decrease in the second scenario. Ultimately, society welfare would improve in all scenarios. We presents and synthesizes the CGE model which could be used to analyze trade liberalization policy issue in developing countries (like Iran), and thus provides information that policymakers can use to improve the pharmacy economics.

The construction of general basis functions in reweighting ensemble dynamics simulations: Reproduce equilibrium distribution in complex systems from multiple short simulation trajectories

NASA Astrophysics Data System (ADS)

Zhang, Chuan-Biao; Ming, Li; Xin, Zhou

2015-12-01

Ensemble simulations, which use multiple short independent trajectories from dispersive initial conformations, rather than a single long trajectory as used in traditional simulations, are expected to sample complex systems such as biomolecules much more efficiently. The re-weighted ensemble dynamics (RED) is designed to combine these short trajectories to reconstruct the global equilibrium distribution. In the RED, a number of conformational functions, named as basis functions, are applied to relate these trajectories to each other, then a detailed-balance-based linear equation is built, whose solution provides the weights of these trajectories in equilibrium distribution. Thus, the sufficient and efficient selection of basis functions is critical to the practical application of RED. Here, we review and present a few possible ways to generally construct basis functions for applying the RED in complex molecular systems. Especially, for systems with less priori knowledge, we could generally use the root mean squared deviation (RMSD) among conformations to split the whole conformational space into a set of cells, then use the RMSD-based-cell functions as basis functions. We demonstrate the application of the RED in typical systems, including a two-dimensional toy model, the lattice Potts model, and a short peptide system. The results indicate that the RED with the constructions of basis functions not only more efficiently sample the complex systems, but also provide a general way to understand the metastable structure of conformational space. Project supported by the National Natural Science Foundation of China (Grant No. 11175250).

Linear dynamics of classical spin as Mobius transformation

DOE PAGES

Galda, Alexey; Vinokur, Valerii М.

2017-04-26

Though the overwhelming majority of natural processes occur far from the equilibrium, general theoretical approaches to non-equilibrium phase transitions remain scarce. Recent breakthroughs introduced a description of open dissipative systems in terms of non-Hermitian quantum mechanics enabling the identification of a class of non-equilibrium phase transitions associated with the loss of combined parity (reflection) and time-reversal symmetries. Here we report that the time evolution of a single classical spin (e.g. monodomain ferromagnet) governed by the Landau-Lifshitz-Gilbert-Slonczewski equation in the absence of magnetic anisotropy terms is described by a Mobius transformation in complex stereographic coordinates. We identify the parity-time symmetry-breaking phasemore » transition occurring in spin-transfer torque-driven linear spin systems as a transition between hyperbolic and loxodromic classes of Mobius transformations, with the critical point of the transition corresponding to the parabolic transformation. However, this establishes the understanding of non-equilibrium phase transitions as topological transitions in configuration space.« less

New insights for mesospheric OH: multi-quantum vibrational relaxation as a driver for non-local thermodynamic equilibrium

PubMed Central

Kalogerakis, Konstantinos S.; Matsiev, Daniel; Cosby, Philip C.; Dodd, James A.; Falcinelli, Stefano; Hedin, Jonas; Kutepov, Alexander A.; Noll, Stefan; Panka, Peter A.; Romanescu, Constantin; Thiebaud, Jérôme E.

2018-01-01

The question of whether mesospheric OH(υ) rotational population distributions are in equilibrium with the local kinetic temperature has been debated over several decades. Despite several indications for the existence of non-equilibrium effects, the general consensus has been that emissions originating from low rotational levels are thermalized. Sky spectra simultaneously observing several vibrational levels demonstrated reproducible trends in the extracted OH(υ) rotational temperatures as a function of vibrational excitation. Laboratory experiments provided information on rotational energy transfer and direct evidence for fast multi-quantum OH(high-υ) vibrational relaxation by O atoms. We examine the relationship of the new relaxation pathways with the behavior exhibited by OH(υ) rotational population distributions. Rapid OH(high-υ) + O multi-quantum vibrational relaxation connects high and low vibrational levels and enhances the hot tail of the OH(low-υ) rotational distributions. The effective rotational temperatures of mesospheric OH(υ) are found to deviate from local thermodynamic equilibrium for all observed vibrational levels. PMID:29503514

Equilibrium shapes of a heterogeneous bubble in an electric field: a variational formulation and numerical verifications

NASA Astrophysics Data System (ADS)

Wang, Hanxiong; Liu, Liping; Liu, Dong

2017-03-01

The equilibrium shape of a bubble/droplet in an electric field is important for electrowetting over dielectrics (EWOD), electrohydrodynamic (EHD) enhancement for heat transfer and electro-deformation of a single biological cell among others. In this work, we develop a general variational formulation in account of electro-mechanical couplings. In the context of EHD, we identify the free energy functional and the associated energy minimization problem that determines the equilibrium shape of a bubble in an electric field. Based on this variational formulation, we implement a fixed mesh level-set gradient method for computing the equilibrium shapes. This numerical scheme is efficient and validated by comparing with analytical solutions at the absence of electric field and experimental results at the presence of electric field. We also present simulation results for zero gravity which will be useful for space applications. The variational formulation and numerical scheme are anticipated to have broad applications in areas of EWOD, EHD and electro-deformation in biomechanics.

The magnetic non-equilibrium of buoyant flux tubes in the solar corona

NASA Technical Reports Server (NTRS)

Browning, P. K.; Priest, E. R.

1984-01-01

The magnetic field in the convection zone and photosphere of the sun exists mostly as concentrated tubes of magnetic flux. It is, therefore, necessary to study the basic properties of magnetic flux tubes to obtain a basis for understanding the behavior of the sun's magnetic field. The present investigation is concerned with the global equilibrium shape of a flux tube in the stratified solar atmosphere. A fundamental property of isolated flux tubes is magnetic buoyancy. Attention is given to flux tubes with external field, and twisted flux tubes. It is shown that the analysis of Parker (1975, 1979) and Spruit (1981) for calculating the equilibrium of a slender flux tube in a stratified atmosphere may be extended to more general situations. The slender tube approximation provides a method of solving the problem of modeling the overall curvature of flux tubes. It is found that for a twisted flux tube, there can be two possible equilibrium values of the height.

Essays on equity-efficiency trade offs in energy and climate policies

NASA Astrophysics Data System (ADS)

Sesmero, Juan P.

Economic efficiency and societal equity are two important goals of public policy. Energy and climate policies have the potential to affect both. Efficiency is increased by substituting low-carbon energy for fossil energy (mitigating an externality) while equity is served if such substitution enhances consumption opportunities of unfavored groups (low income households or future generations). However policies that are effective in reducing pollution may not be so effective in redistributing consumption and vice-versa. This dissertation explores potential trade-offs between equity and efficiency arising in energy and climate policies. Chapter 1 yields two important results. First, while effective in reducing pollution, energy efficiency policies may fall short in protecting future generations from resource depletion. Second, deployment of technologies that increase the ease with which capital can substitute for energy may enhance the ability of societies to sustain consumption and achieve intertemporal equity. Results in Chapter 1 imply that technologies more intensive in capital and materials and less intensive in carbon such as corn ethanol may be effective in enhancing intertemporal equity. However the effectiveness of corn ethanol (relative to other technologies) in reducing emissions will depend upon the environmental performance of the industry. Chapter 2 measures environmental efficiency of ethanol plants, identifies ways to enhance performance, and calculates the cost of such improvements based on a survey of ethanol plants in the US. Results show that plants may be able to increase profits and reduce emissions simultaneously rendering the ethanol industry more effective in tackling efficiency. Finally while cap and trade proposals are designed to correcting a market failure by reducing pollution, allocation of emission allowances may affect income distribution and, hence, intra-temporal equity. Chapter 3 proves that under plausible conditions on preferences and technology increasing efficiency requires greater transfers to low income households the higher the effect of these transfers on the price of permits and the lower their effect on the price of consumption goods. This denotes market conditions under which efficiency and equity are complementary goals.

A Computer Algebra Approach to Solving Chemical Equilibria in General Chemistry

ERIC Educational Resources Information Center

Kalainoff, Melinda; Lachance, Russ; Riegner, Dawn; Biaglow, Andrew

2012-01-01

In this article, we report on a semester-long study of the incorporation into our general chemistry course, of advanced algebraic and computer algebra techniques for solving chemical equilibrium problems. The method presented here is an alternative to the commonly used concentration table method for describing chemical equilibria in general…

Physics Meets Art in the General Education Core

ERIC Educational Resources Information Center

Dark, Marta L.; Hylton, Derrick J.

2018-01-01

This article describes a general education course offering, Physics and the Arts. During the development of this course, physics and arts faculty collaborated closely. We cover the usual physics phenomena for such a course--light, color, and sound--in addition to gravity, equilibrium, and spacetime. Goals of the course are to increase students'…

Freight transportation improvements and the economy

DOT National Transportation Integrated Search

2004-06-01

This report summarizes the results of the Federal Highway Administrations (FHWAs) work on the economic benefits of transportation improvements using macroeconomic, microeconomic, and general equilibrium approaches. Detailed information is provi...

Financial Structure and Economic Welfare: Applied General Equilibrium Development Economics.

PubMed

Townsend, Robert

2010-09-01

This review provides a common framework for researchers thinking about the next generation of micro-founded macro models of growth, inequality, and financial deepening, as well as direction for policy makers targeting microfinance programs to alleviate poverty. Topics include treatment of financial structure general equilibrium models: testing for as-if-complete markets or other financial underpinnings; examining dual-sector models with both a perfectly intermediated sector and a sector in financial autarky, as well as a second generation of these models that embeds information problems and other obstacles to trade; designing surveys to capture measures of income, investment/savings, and flow of funds; and aggregating individuals and households to the level of network, village, or national economy. The review concludes with new directions that overcome conceptual and computational limitations.

Determination of the spin and recovery characteristics of a typical low-wing general aviation design

NASA Technical Reports Server (NTRS)

Tischler, M. B.; Barlow, J. B.

1980-01-01

The equilibrium spin technique implemented in a graphical form for obtaining spin and recovery characteristics from rotary balance data is outlined. Results of its application to recent rotary balance tests of the NASA Low-Wing General Aviation Aircraft are discussed. The present results, which are an extension of previously published findings, indicate the ability of the equilibrium method to accurately evaluate spin modes and recovery control effectiveness. A comparison of the calculated results with available spin tunnel and full scale findings is presented. The technique is suitable for preliminary design applications as determined from the available results and data base requirements. A full discussion of implementation considerations and a summary of the results obtained from this method to date are presented.

The Navy/NASA Engine Program (NNEP89): Interfacing the program for the calculation of complex Chemical Equilibrium Compositions (CEC)

NASA Technical Reports Server (NTRS)

Gordon, Sanford

1991-01-01

The NNEP is a general computer program for calculating aircraft engine performance. NNEP has been used extensively to calculate the design and off-design (matched) performance of a broad range of turbine engines, ranging from subsonic turboprops to variable cycle engines for supersonic transports. Recently, however, there has been increased interest in applications for which NNEP is not capable of simulating, such as the use of alternate fuels including cryogenic fuels and the inclusion of chemical dissociation effects at high temperatures. To overcome these limitations, NNEP was extended by including a general chemical equilibrium method. This permits consideration of any propellant system and the calculation of performance with dissociation effects. The new extended program is referred to as NNEP89.

Transfer potentials shape and equilibrate monetary systems

NASA Astrophysics Data System (ADS)

Fischer, Robert; Braun, Dieter

2003-04-01

We analyze a monetary system of random money transfer on the basis of double entry bookkeeping. Without boundary conditions, we do not reach a price equilibrium and violate text-book formulas of economist's quantity theory ( MV= PQ). To match the resulting quantity of money with the model assumption of a constant price, we have to impose boundary conditions. They either restrict specific transfers globally or impose transfers locally. Both connect through a general framework of transfer potentials. We show that either restricted or imposed transfers can shape Gaussian, tent-shape exponential, Boltzmann-exponential, pareto or periodic equilibrium distributions. We derive the master equation and find its general time-dependent approximate solution. An equivalent of quantity theory for random money transfer under the boundary conditions of transfer potentials is given.

Financial Structure and Economic Welfare: Applied General Equilibrium Development Economics

PubMed Central

Townsend, Robert

2010-01-01

This review provides a common framework for researchers thinking about the next generation of micro-founded macro models of growth, inequality, and financial deepening, as well as direction for policy makers targeting microfinance programs to alleviate poverty. Topics include treatment of financial structure general equilibrium models: testing for as-if-complete markets or other financial underpinnings; examining dual-sector models with both a perfectly intermediated sector and a sector in financial autarky, as well as a second generation of these models that embeds information problems and other obstacles to trade; designing surveys to capture measures of income, investment/savings, and flow of funds; and aggregating individuals and households to the level of network, village, or national economy. The review concludes with new directions that overcome conceptual and computational limitations. PMID:21037939

Nonlinear ballooning modes in tokamaks: stability and saturation

NASA Astrophysics Data System (ADS)

Ham, C. J.; Cowley, S. C.; Brochard, G.; Wilson, H. R.

2018-07-01

The nonlinear dynamics of magneto-hydrodynamic ballooning mode perturbations is conjectured to be characterised by the motion of isolated elliptical flux tubes. The theory of stability, dynamics and saturation of such tubes in tokamaks is developed using a generalised Archimedes’ principle. The equation of motion for a tube moving against a drag force in a general axisymmetric equilibrium is derived and then applied to a simplified ‘s–α’ equilibrium. The perturbed nonlinear tube equilibrium (saturated) states are investigated in an ‘s–α’ equilibrium with specific pressure and magnetic shear profiles. The energy of these nonlinear (ballooning) saturated states is calculated. In some cases, particularly at low magnetic shear, these finitely displaced states can have a lower energy than the equilibrium state even if the profile is linearly stable to ballooning modes (infinitesimal tube displacements) at all radii. Thus nonlinear ballooning modes can be metastable. The amplitude of the saturated tube displacement in such cases can be as large as the pressure gradient scale length. We conjecture that triggering a transition into these filamentary states can lead to hard instability limits. A short survey of different pressure profiles is presented to illustrate the variety of behaviour of perturbed elliptical flux tubes.

Bounded energy states in homogeneous turbulent shear flow: An alternative view

NASA Technical Reports Server (NTRS)

Bernard, Peter S.; Speziale, Charles G.

1990-01-01

The equilibrium structure of homogeneous turbulent shear flow is investigated from a theoretical standpoint. Existing turbulence models, in apparent agreement with physical and numerical experiments, predict an unbounded exponential time growth of the turbulent kinetic energy and dissipation rate; only the anisotropy tensor and turbulent time scale reach a structural equilibrium. It is shown that if vortex stretching is accounted for in the dissipation rate transport equation, then there can exist equilibrium solutions, with bounded energy states, where the turbulence production is balanced by its dissipation. Illustrative calculations are present for a k-epsilon model modified to account for vortex stretching. The calculations indicate an initial exponential time growth of the turbulent kinetic energy and dissipation rate for elapsed times that are as large as those considered in any of the previously conducted physical or numerical experiments on homogeneous shear flow. However, vortex stretching eventually takes over and forces a production-equals-dissipation equilibrium with bounded energy states. The validity of this result is further supported by an independent theoretical argument. It is concluded that the generally accepted structural equilibrium for homogeneous shear flow with unbounded component energies is in need of re-examination.

Equilibrium relations and bipolar cognitive mapping for online analytical processing with applications in international relations and strategic decision support.

PubMed

Zhang, Wen-Ran

2003-01-01

Bipolar logic, bipolar sets, and equilibrium relations are proposed for bipolar cognitive mapping and visualization in online analytical processing (OLAP) and online analytical mining (OLAM). As cognitive models, cognitive maps (CMs) hold great potential for clustering and visualization. Due to the lack of a formal mathematical basis, however, CM-based OLAP and OLAM have not gained popularity. Compared with existing approaches, bipolar cognitive mapping has a number of advantages. First, bipolar CMs are formal logical models as well as cognitive models. Second, equilibrium relations (with polarized reflexivity, symmetry, and transitivity), as bipolar generalizations and fusions of equivalence relations, provide a theoretical basis for bipolar visualization and coordination. Third, an equilibrium relation or CM induces bipolar partitions that distinguish disjoint coalition subsets not involved in any conflict, disjoint coalition subsets involved in a conflict, disjoint conflict subsets, and disjoint harmony subsets. Finally, equilibrium energy analysis leads to harmony and stability measures for strategic decision and multiagent coordination. Thus, this work bridges a gap for CM-based clustering and visualization in OLAP and OLAM. Basic ideas are illustrated with example CMs in international relations.

Equilibrium problems for Raney densities

NASA Astrophysics Data System (ADS)

Forrester, Peter J.; Liu, Dang-Zheng; Zinn-Justin, Paul

2015-07-01

The Raney numbers are a class of combinatorial numbers generalising the Fuss-Catalan numbers. They are indexed by a pair of positive real numbers (p, r) with p > 1 and 0 < r ⩽ p, and form the moments of a probability density function. For certain (p, r) the latter has the interpretation as the density of squared singular values for certain random matrix ensembles, and in this context equilibrium problems characterising the Raney densities for (p, r) = (θ + 1, 1) and (θ/2 + 1, 1/2) have recently been proposed. Using two different techniques—one based on the Wiener-Hopf method for the solution of integral equations and the other on an analysis of the algebraic equation satisfied by the Green's function—we establish the validity of the equilibrium problems for general θ > 0 and similarly use both methods to identify the equilibrium problem for (p, r) = (θ/q + 1, 1/q), θ > 0 and q \\in Z+ . The Wiener-Hopf method is used to extend the latter to parameters (p, r) = (θ/q + 1, m + 1/q) for m a non-negative integer, and also to identify the equilibrium problem for a family of densities with moments given by certain binomial coefficients.

Path-space variational inference for non-equilibrium coarse-grained systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harmandaris, Vagelis, E-mail: harman@uoc.gr; Institute of Applied and Computational Mathematics; Kalligiannaki, Evangelia, E-mail: ekalligian@tem.uoc.gr

In this paper we discuss information-theoretic tools for obtaining optimized coarse-grained molecular models for both equilibrium and non-equilibrium molecular simulations. The latter are ubiquitous in physicochemical and biological applications, where they are typically associated with coupling mechanisms, multi-physics and/or boundary conditions. In general the non-equilibrium steady states are not known explicitly as they do not necessarily have a Gibbs structure. The presented approach can compare microscopic behavior of molecular systems to parametric and non-parametric coarse-grained models using the relative entropy between distributions on the path space and setting up a corresponding path-space variational inference problem. The methods can become entirelymore » data-driven when the microscopic dynamics are replaced with corresponding correlated data in the form of time series. Furthermore, we present connections and generalizations of force matching methods in coarse-graining with path-space information methods. We demonstrate the enhanced transferability of information-based parameterizations to different observables, at a specific thermodynamic point, due to information inequalities. We discuss methodological connections between information-based coarse-graining of molecular systems and variational inference methods primarily developed in the machine learning community. However, we note that the work presented here addresses variational inference for correlated time series due to the focus on dynamics. The applicability of the proposed methods is demonstrated on high-dimensional stochastic processes given by overdamped and driven Langevin dynamics of interacting particles.« less

Near-equilibrium desorption of helium films

NASA Astrophysics Data System (ADS)

Weimer, M.; Housley, R. M.; Goodstein, D. L.

1987-10-01

The thermal desorption of helium films in the presence of their equilibrium vapor is studied experimentally for small but rapid departures from ambient temperature. The results are analyzed within the framework of a quasithermodynamic phenomenological model based on detailed balance. Under the usual experimental conditions, isothermal desorption at the temperature of the substrate is a general prediction of the model which seems to be substantiated. For realistic adsorption isotherms the time evolution of the net desorption flux nevertheless appears to be governed by a highly nonlinear equation. In such circumstances, a number of characteristic relaxation times may be identified. These time scales are distinct from, and in general unrelated to, the coverage-dependent mean lifetime of an atom on the surface. To characterize the overall nonlinear evolution towards steady state, a global time scale, defined in terms of both initial- and steady-state properties, is introduced to summarize the experimental data. Internal evidence suggests a criterion for judging when collisions among desorbed atoms are unimportant. When this condition is satisfied, data for near-equilibrium desorption agree well with the predictions of the model. Combining our results with earlier data at higher substrate temperatures and different ambient conditions, the overall picture is consistent with scaling properties implied by the theory. We show that the values of the parameters deduced from a Frenkel-Arrhenius parametrization of the global relaxation times, as well as a variety of other aspects of desorption kinetics, are actually consequences of the shape of the equilibrium adsorption isotherm.

Shallow discounting of delayed cocaine by male rhesus monkeys when immediate food is the choice alternative.

PubMed

Huskinson, Sally L; Myerson, Joel; Green, Leonard; Rowlett, James K; Woolverton, William L; Freeman, Kevin B

2016-12-01

Huskinson et al. (2015) recently examined delay discounting in monkeys choosing between an immediate drug (cocaine) reinforcer and a delayed nondrug (food) reinforcer. The present experiment examined the reverse situation: choice between immediate nondrug (food) and delayed drug (cocaine) reinforcers. Whereas the former choice situation exemplifies drug abuse from a delay-discounting perspective, our interest in the latter choice situation is derived from the observation that drug abusers, who characteristically are associated with impulsive choice, typically must devote considerable time to procuring drugs, often at the expense of immediate nondrug alternatives. Accordingly, we analyzed 3 male rhesus monkeys' choices between immediate food and delayed cocaine (0.1 and 0.2 mg/kg/injection) using a hyperbolic model that allowed us to compare discounting rates between qualitatively different reinforcers. Choice of immediate food increased with food amount, and choice functions generally shifted leftward as delay to cocaine increased, indicating a decrease in the subjective value of cocaine. Compared with our previous delay-discounting experiment with immediate cocaine versus delayed food, both doses of delayed cocaine were discounted at a shallow rate. The present results demonstrate that rhesus monkeys will tolerate relatively long delays in an immediate-food versus delayed-drug situation, suggesting that in intertemporal choices between cocaine and food, the subjective value of cocaine is less affected by the delay until reinforcement than is the subjective value of delayed food. More generally, the present findings suggest that although drug abusers may choose impulsively when immediate drug reinforcement is available, they exercise self-control in the acquisition of a highly preferred, delayed drug reinforcer. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Non-equilibrium magnetic colloidal dispersions at liquid-air interfaces: dynamic patterns, magnetic order and self-assembled swimmers.

PubMed

Snezhko, Alexey

2011-04-20

Colloidal dispersions of interacting particles subjected to an external periodic forcing often develop nontrivial self-assembled patterns and complex collective behavior. A fundamental issue is how collective ordering in such non-equilibrium systems arises from the dynamics of discrete interacting components. In addition, from a practical viewpoint, by working in regimes far from equilibrium new self-organized structures which are generally not available through equilibrium thermodynamics can be created. In this review spontaneous self-assembly phenomena in magnetic colloidal dispersions suspended at liquid-air interfaces and driven out of equilibrium by an alternating magnetic field are presented. Experiments reveal a new type of nontrivially ordered self-assembled structures emerging in such systems in a certain range of excitation parameters. These dynamic structures emerge as a result of the competition between magnetic and hydrodynamic forces and have complex unconventional magnetic ordering. Nontrivial self-induced hydrodynamic fields accompany each out-of-equilibrium pattern. Spontaneous symmetry breaking of the self-induced surface flows leading to a formation of self-propelled microstructures has been discovered. Some features of the self-localized structures can be understood in the framework of the amplitude equation (Ginzburg-Landau type equation) for parametric waves coupled to the conservation law equation describing the evolution of the magnetic particle density and the Navier-Stokes equation for hydrodynamic flows. To understand the fundamental microscopic mechanisms governing self-assembly processes in magnetic colloidal dispersions at liquid-air interfaces a first-principle model for a non-equilibrium self-assembly is presented. The latter model allows us to capture in detail the entire process of out-of-equilibrium self-assembly in the system and reproduces most of the observed phenomenology.

Characteristics of spondylotic myelopathy on 3D driven-equilibrium fast spin echo and 2D fast spin echo magnetic resonance imaging: a retrospective cross-sectional study.

PubMed

Abdulhadi, Mike A; Perno, Joseph R; Melhem, Elias R; Nucifora, Paolo G P

2014-01-01

In patients with spinal stenosis, magnetic resonance imaging of the cervical spine can be improved by using 3D driven-equilibrium fast spin echo sequences to provide a high-resolution assessment of osseous and ligamentous structures. However, it is not yet clear whether 3D driven-equilibrium fast spin echo sequences adequately evaluate the spinal cord itself. As a result, they are generally supplemented by additional 2D fast spin echo sequences, adding time to the examination and potential discomfort to the patient. Here we investigate the hypothesis that in patients with spinal stenosis and spondylotic myelopathy, 3D driven-equilibrium fast spin echo sequences can characterize cord lesions equally well as 2D fast spin echo sequences. We performed a retrospective analysis of 30 adult patients with spondylotic myelopathy who had been examined with both 3D driven-equilibrium fast spin echo sequences and 2D fast spin echo sequences at the same scanning session. The two sequences were inspected separately for each patient, and visible cord lesions were manually traced. We found no significant differences between 3D driven-equilibrium fast spin echo and 2D fast spin echo sequences in the mean number, mean area, or mean transverse dimensions of spondylotic cord lesions. Nevertheless, the mean contrast-to-noise ratio of cord lesions was decreased on 3D driven-equilibrium fast spin echo sequences compared to 2D fast spin echo sequences. These findings suggest that 3D driven-equilibrium fast spin echo sequences do not need supplemental 2D fast spin echo sequences for the diagnosis of spondylotic myelopathy, but they may be less well suited for quantitative signal measurements in the spinal cord.

Einstein's osmotic equilibrium of colloidal suspensions in conservative force fields

NASA Astrophysics Data System (ADS)

Fu, Jinxin; Ou-Yang, H. Daniel

2014-09-01

Predicted by Einstein in his 1905 paper on Brownian motion, colloidal particles in suspension reach osmotic equilibrium under gravity. The idea was demonstrated by J.B. Perrin to win Nobel Prize in Physics in 1926. We show Einstein's equation for osmotic equilibrium can be applied to colloids in a conservative force field generated by optical gradient forces. We measure the osmotic equation of state of 100nm Polystyrene latex particles in the presence of KCl salt and PEG polymer. We also obtain the osmotic compressibility, which is important for determining colloidal stability and the internal chemical potential, which is useful for predicting the phase transition of colloidal systems. This generalization allows for the use of any conservative force fields for systems ranging from colloidal systems to macromolecular solutions.

Fluctuations in Mass-Action Equilibrium of Protein Binding Networks

NASA Astrophysics Data System (ADS)

Yan, Koon-Kiu; Walker, Dylan; Maslov, Sergei

2008-12-01

We consider two types of fluctuations in the mass-action equilibrium in protein binding networks. The first type is driven by slow changes in total concentrations of interacting proteins. The second type (spontaneous) is caused by quickly decaying thermodynamic deviations away from equilibrium. We investigate the effects of network connectivity on fluctuations by comparing them to scenarios in which the interacting pair is isolated from the network and analytically derives bounds on fluctuations. Collective effects are shown to sometimes lead to large amplification of spontaneous fluctuations. The strength of both types of fluctuations is positively correlated with the complex connectivity and negatively correlated with complex concentration. Our general findings are illustrated using a curated network of protein interactions and multiprotein complexes in baker’s yeast, with empirical protein concentrations.

Non-equilibrium in cosmology

NASA Astrophysics Data System (ADS)

Pietroni, M.

2009-02-01

All the non-trivial features of the Universe we see around us, such as particles, stars, galaxies, and clusters of galaxies, are the result of non-equilibrium processes in the cosmic evolution. These lectures aim to provide some general background in cosmology and to examine specific, and notable, examples of departures from thermal equilibrium. They are organized as follows: 1) Overview of the thermal history of the Universe after the Big Bang: the relevant time-scales and the mechanism of particle decoupling from the themal bath; 2) Explicit examples of cosmic relics: nucleosynthesis, photons and the cosmic microwave background, neutrinos, and cold dark matter; 3) Baryogenesis: the generation of the baryon asymmetry of the Universe; 4) The formation of cosmic structures (galaxies, clusters of galaxies): from the Vlasov equation to the renormalization group.

A Simple Method for Automated Equilibration Detection in Molecular Simulations.

PubMed

Chodera, John D

2016-04-12

Molecular simulations intended to compute equilibrium properties are often initiated from configurations that are highly atypical of equilibrium samples, a practice which can generate a distinct initial transient in mechanical observables computed from the simulation trajectory. Traditional practice in simulation data analysis recommends this initial portion be discarded to equilibration, but no simple, general, and automated procedure for this process exists. Here, we suggest a conceptually simple automated procedure that does not make strict assumptions about the distribution of the observable of interest in which the equilibration time is chosen to maximize the number of effectively uncorrelated samples in the production timespan used to compute equilibrium averages. We present a simple Python reference implementation of this procedure and demonstrate its utility on typical molecular simulation data.

The dynamics of the de Sitter resonance

NASA Astrophysics Data System (ADS)

Celletti, Alessandra; Paita, Fabrizio; Pucacco, Giuseppe

2018-02-01

We study the dynamics of the de Sitter resonance, namely the stable equilibrium configuration of the first three Galilean satellites. We clarify the relation between this family of configurations and the more general Laplace resonant states. In order to describe the dynamics around the de Sitter stable equilibrium, a one-degree-of-freedom Hamiltonian normal form is constructed and exploited to identify initial conditions leading to the two families. The normal form Hamiltonian is used to check the accuracy in the location of the equilibrium positions. Besides, it gives a measure of how sensitive it is with respect to the different perturbations acting on the system. By looking at the phase plane of the normal form, we can identify a Laplace-like configuration, which highlights many substantial aspects of the observed one.

Spatial firm competition in two dimensions with linear transportation costs: simulations and analytical results

NASA Astrophysics Data System (ADS)

Roncoroni, Alan; Medo, Matus

2016-12-01

Models of spatial firm competition assume that customers are distributed in space and transportation costs are associated with their purchases of products from a small number of firms that are also placed at definite locations. It has been long known that the competition equilibrium is not guaranteed to exist if the most straightforward linear transportation costs are assumed. We show by simulations and also analytically that if periodic boundary conditions in a plane are assumed, the equilibrium exists for a pair of firms at any distance. When a larger number of firms is considered, we find that their total equilibrium profit is inversely proportional to the square root of the number of firms. We end with a numerical investigation of the system's behavior for a general transportation cost exponent.

A simple method for automated equilibration detection in molecular simulations

PubMed Central

Chodera, John D.

2016-01-01

Molecular simulations intended to compute equilibrium properties are often initiated from configurations that are highly atypical of equilibrium samples, a practice which can generate a distinct initial transient in mechanical observables computed from the simulation trajectory. Traditional practice in simulation data analysis recommends this initial portion be discarded to equilibration, but no simple, general, and automated procedure for this process exists. Here, we suggest a conceptually simple automated procedure that does not make strict assumptions about the distribution of the observable of interest, in which the equilibration time is chosen to maximize the number of effectively uncorrelated samples in the production timespan used to compute equilibrium averages. We present a simple Python reference implementation of this procedure, and demonstrate its utility on typical molecular simulation data. PMID:26771390

Simplified Thermo-Chemical Modelling For Hypersonic Flow

NASA Astrophysics Data System (ADS)

Sancho, Jorge; Alvarez, Paula; Gonzalez, Ezequiel; Rodriguez, Manuel

2011-05-01

Hypersonic flows are connected with high temperatures, generally associated with strong shock waves that appear in such flows. At high temperatures vibrational degrees of freedom of the molecules may become excited, the molecules may dissociate into atoms, the molecules or free atoms may ionize, and molecular or ionic species, unimportant at lower temperatures, may be formed. In order to take into account these effects, a chemical model is needed, but this model should be simplified in order to be handled by a CFD code, but with a sufficient precision to take into account the physics more important. This work is related to a chemical non-equilibrium model validation, implemented into a commercial CFD code, in order to obtain the flow field around bodies in hypersonic flow. The selected non-equilibrium model is composed of seven species and six direct reactions together with their inverse. The commercial CFD code where the non- equilibrium model has been implemented is FLUENT. For the validation, the X38/Sphynx Mach 20 case is rebuilt on a reduced geometry, including the 1/3 Lref forebody. This case has been run in laminar regime, non catalytic wall and with radiative equilibrium wall temperature. The validated non-equilibrium model is applied to the EXPERT (European Experimental Re-entry Test-bed) vehicle at a specified trajectory point (Mach number 14). This case has been run also in laminar regime, non catalytic wall and with radiative equilibrium wall temperature.

Chemical properties of ground water and their corrosion and encrustation effects on wells

USGS Publications Warehouse

Barnes, Ivan; Clarke, Frank Eldridge

1969-01-01

Well waters in Egypt, Nigeria, and West Pakistan were studied for their chemical properties and corrosive or encrusting behavior. From the chemical composition of the waters, reaction states with reference to equilibrium were tested for 29 possible coexisting oxides, carbonates, sulfides, and elements. Of the 29 solids considered, only calcite, CaCO3, and ferric hydroxide, Fe(OH)3, showed any correlation with the corrosiveness of the waters to mild steel (iron metal). All 39 of the waters tested were out of equilibrium with iron metal, but those waters in equilibrium or supersaturated with both calcite and ferric hydroxide were the least corrosive. Supersaturation with other solid phases apparently was unrelated to corrosion. A number of solids may form surface deposits in wells and lead to decreased yields by fouling well intakes (screens and gravel packs) or increasing friction losses in casings. Calcite, CaCO3; ferric hydroxide, Fe(OH)3; magnetite, Fe3O4; siderite, FeCO3; hausmannite, Mn304 (tetragonal); manganese spinel, Mn3O4 (isometric); three iron sulfides mackinawite, FeS (tetragonal); greigite, Fe3S4 (isometric); and smythite, Fe3S4 (rhombohedral)-copper hydroxide, Co(OH)2; and manganese hydroxide, Mn(OH)2, were all at least tentatively identified in the deposits sampled. Of geochemical interest is the demonstration that simple stable equilibrium models fail in nearly every case to predict compositions of water yielded by the wells studied. Only one stable phase (calcite) was found to exhibit behavior approximately predictable from stable equilibrium considerations. No other stable phase was found to behave as would be predicted from equilibrium considerations. All the solids found to precipitate (except calcite) are metastable in that they are not the least soluble phases possible in the systems studied. In terms of metastable equilibrium, siderite and ferric hydroxide behave approximately as would be predicted from equilibrium considerations, but both are metastable and the presence of neither would be anticipated if only the most stable phases were considered. The behaviors of none of the other solids would be predictable from either stable or metastable equilibrium considerations. An unanswered problem raised by the study reported here is how, or by what paths, truly stable phases form if first precipitates are generally metastable.The utility of the findings in well design and operation is in no way impaired by the general lack of equilibrium. Conditions leading to either corrosion (which is related to lack of supersaturation with protective phases), or encrustation (supersaturation with phases that were found to precipitate), or both, apparently can be identified. The application of the methods described can be of great importance in developing unexploited ground-water resources in that certain practical problems can be identified before extensive well construction and unnecessary well failure.

The relativistic equations of stellar structure and evolution. Stars with degenerate neutron cores. 1: Structure of equilibrium models

NASA Technical Reports Server (NTRS)

Thorne, K. S.; Zytkow, A. N.

1976-01-01

The general relativistic equations of stellar structure and evolution are reformulated in a notation which makes easy contact with Newtonian theory. Also, a general relativistic version of the mixing-length formalism for convection is presented. Finally, it is argued that in previous work on spherical systems general relativity theorists have identified the wrong quantity as "total mass-energy inside radius r."

A Dynamic Model for Modern Military Conflict.

DTIC Science & Technology

1982-10-01

within the generalized form of the Lotka - Volterra equations, that can account for the important interactions of modern military conflicts described in...Mx + These equations are seen to be of the generalized Lotka - Volterra form; however, only 20 of the 32 parameters that might possibly be included...determine one equilibrium as the solution of a system of linear equations. The method is derived for the general nth order Lotka - Volterra model in

Coupling Climate Models and Forward-Looking Economic Models

NASA Astrophysics Data System (ADS)

Judd, K.; Brock, W. A.

2010-12-01

Authors: Dr. Kenneth L. Judd, Hoover Institution, and Prof. William A. Brock, University of Wisconsin Current climate models range from General Circulation Models (GCM’s) with millions of degrees of freedom to models with few degrees of freedom. Simple Energy Balance Climate Models (EBCM’s) help us understand the dynamics of GCM’s. The same is true in economics with Computable General Equilibrium Models (CGE’s) where some models are infinite-dimensional multidimensional differential equations but some are simple models. Nordhaus (2007, 2010) couples a simple EBCM with a simple economic model. One- and two- dimensional ECBM’s do better at approximating damages across the globe and positive and negative feedbacks from anthroprogenic forcing (North etal. (1981), Wu and North (2007)). A proper coupling of climate and economic systems is crucial for arriving at effective policies. Brock and Xepapadeas (2010) have used Fourier/Legendre based expansions to study the shape of socially optimal carbon taxes over time at the planetary level in the face of damages caused by polar ice cap melt (as discussed by Oppenheimer, 2005) but in only a “one dimensional” EBCM. Economists have used orthogonal polynomial expansions to solve dynamic, forward-looking economic models (Judd, 1992, 1998). This presentation will couple EBCM climate models with basic forward-looking economic models, and examine the effectiveness and scaling properties of alternative solution methods. We will use a two dimensional EBCM model on the sphere (Wu and North, 2007) and a multicountry, multisector regional model of the economic system. Our aim will be to gain insights into intertemporal shape of the optimal carbon tax schedule, and its impact on global food production, as modeled by Golub and Hertel (2009). We will initially have limited computing resources and will need to focus on highly aggregated models. However, this will be more complex than existing models with forward-looking economic modules, and the initial models will help guide the construction of more refined models that can effectively use more powerful computational environments to analyze economic policies related to climate change. REFERENCES Brock, W., Xepapadeas, A., 2010, “An Integration of Simple Dynamic Energy Balance Climate Models and Ramsey Growth Models,” Department of Economics, University of Wisconsin, Madison, and University of Athens. Golub, A., Hertel, T., etal., 2009, “The opportunity cost of land use and the global potential for greenhouse gas mitigation in agriculture and forestry,” RESOURCE AND ENERGY ECONOMICS, 31, 299-319. Judd, K., 1992, “Projection methods for solving aggregate growth models,” JOURNAL OF ECONOMIC THEORY, 58: 410-52. Judd, K., 1998, NUMERICAL METHODS IN ECONOMICS, MIT Press, Cambridge, Mass. Nordhaus, W., 2007, A QUESTION OF BALANCE: ECONOMIC MODELS OF CLIMATE CHANGE, Yale University Press, New Haven, CT. North, G., R., Cahalan, R., Coakely, J., 1981, “Energy balance climate models,” REVIEWS OF GEOPHYSICS AND SPACE PHYSICS, Vol. 19, No. 1, 91-121, February Wu, W., North, G. R., 2007, “Thermal decay modes of a 2-D energy balance climate model,” TELLUS, 59A, 618-626.

A neuroeconomic theory of rational addiction and nonlinear time-perception.

PubMed

Takahashi, Taiki

2011-01-01

Neuroeconomic conditions for "rational addiction" (Becker & Murphy 1988) have been unknown. This paper derived the conditions for "rational addiction" by utilizing a nonlinear time-perception theory of "hyperbolic" discounting, which is mathematically equivalent to the q-exponential intertemporal choice model based on Tsallis' statistics. It is shown that (i) Arrow-Pratt measure for temporal cognition corresponds to the degree of irrationality (i.e., Prelec's "decreasing impatience" parameter of temporal discounting) and (ii) rationality in addicts is controlled by a nondimensionalization parameter of the logarithmic time-perception function. Furthermore, the present theory illustrates the possibility that addictive drugs increase impulsivity via dopaminergic neuroadaptation without increasing irrationality. Future directions in the application of the model to studies in neuroeconomics are discussed.

Non-separable time preferences, novelty consumption and body weight: Theory and evidence from the East German transition to capitalism.

PubMed

Dragone, Davide; Ziebarth, Nicolas R

2017-01-01

This paper develops a dynamic model to illustrate how diet and body weight change when novel food products become available to consumers. We propose a microfounded test to empirically discriminate between habit and taste formation in intertemporal preferences. Moreover, we show that 'novelty consumption' and endogenous preferences can explain the persistent correlation between economic development and obesity. By empirically studying the German reunification, we find that East Germans consumed more novel Western food and gained more weight than West Germans when a larger variety of food products became readily accessible after the fall of the Wall. The observed consumption patterns suggest that food consumption features habit formation. Copyright © 2016 Elsevier B.V. All rights reserved.

46 CFR 174.040 - Stability requirements: general.

Code of Federal Regulations, 2011 CFR

2011-10-01

... metacentric height in the upright equilibrium position for the full range of drafts, whether at the operating draft for navigation, towing, or drilling afloat, or at a temporary draft when changing drafts. ...

46 CFR 174.040 - Stability requirements: general.

Code of Federal Regulations, 2014 CFR

2014-10-01

... metacentric height in the upright equilibrium position for the full range of drafts, whether at the operating draft for navigation, towing, or drilling afloat, or at a temporary draft when changing drafts. ...

Turboexpander calculations using a generalized equation of state correlation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, M.S.; Starling, K.E.

1975-01-01

A generalized method for predicting the thermodynamic properties of natural gas fluids has been developed and tested. The results of several comparisons between thermodynamic property values predicted by the method and experimental data are presented. Comparisons of predicted and experimental vapor-liquid equilibrium are presented. These comparisons indicate that the generalized correlation can be used to predict many thermodynamic properties of natural gas and LNG. Turboexpander calculations are presented to show the utility of the generalized correlation for process design calculations.

Climate and the equilibrium state of land surface hydrology parameterizations

NASA Technical Reports Server (NTRS)

Entekhabi, Dara; Eagleson, Peter S.

1991-01-01

For given climatic rates of precipitation and potential evaporation, the land surface hydrology parameterizations of atmospheric general circulation models will maintain soil-water storage conditions that balance the moisture input and output. The surface relative soil saturation for such climatic conditions serves as a measure of the land surface parameterization state under a given forcing. The equilibrium value of this variable for alternate parameterizations of land surface hydrology are determined as a function of climate and the sensitivity of the surface to shifts and changes in climatic forcing are estimated.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Intravaia, F.; Behunin, R. O.; Henkel, C.

Here, we discuss the failure of the Markov approximation in the description of atom-surface fluctuation-induced interactions, both in equilibrium (Casimir-Polder forces) and out of equilibrium (quantum friction). Using general theoretical arguments, we show that the Markov approximation can lead to erroneous predictions of such phenomena with regard to both strength and functional dependencies on system parameters. Particularly, we show that the long-time power-law tails of two-time dipole correlations and their corresponding low-frequency behavior, neglected in the Markovian limit, affect the prediction of the force. These findings highlight the importance of non-Markovian effects in dispersion interactions.

Linearized theory of inhomogeneous multiple 'water-bag' plasmas

NASA Technical Reports Server (NTRS)

Bloomberg, H. W.; Berk, H. L.

1973-01-01

Equations are derived for describing the inhomogeneous equilibrium and small deviations from the equilibrium, giving particular attention to systems with trapped particles. An investigation is conducted of periodic systems with a single trapped-particle water bag, taking into account the behavior of the perturbation equations at the turning points. An outline is provided concerning a procedure for obtaining the eigenvalues. The results of stability calculations connected with the sideband effects are considered along with questions regarding the general applicability of the multiple water-bag approach in stability calculations.

Exact solutions for the selection-mutation equilibrium in the Crow-Kimura evolutionary model.

PubMed

Semenov, Yuri S; Novozhilov, Artem S

2015-08-01

We reformulate the eigenvalue problem for the selection-mutation equilibrium distribution in the case of a haploid asexually reproduced population in the form of an equation for an unknown probability generating function of this distribution. The special form of this equation in the infinite sequence limit allows us to obtain analytically the steady state distributions for a number of particular cases of the fitness landscape. The general approach is illustrated by examples; theoretical findings are compared with numerical calculations. Copyright © 2015. Published by Elsevier Inc.

Shannon information, LMC complexity and Rényi entropies: a straightforward approach.

PubMed

López-Ruiz, Ricardo

2005-04-01

The LMC complexity, an indicator of complexity based on a probabilistic description, is revisited. A straightforward approach allows us to establish the time evolution of this indicator in a near-equilibrium situation and gives us a new insight for interpreting the LMC complexity for a general non equilibrium system. Its relationship with the Rényi entropies is also explained. One of the advantages of this indicator is that its calculation does not require a considerable computational effort in many cases of physical and biological interest.

Discovering a Change in Equilibrium Constant with Change in Ionic Strength: An Empirical Laboratory Experiment for General Chemistry

NASA Astrophysics Data System (ADS)

Stolzberg, Richard J.

1999-05-01

Students are challenged to investigate the hypothesis that an equilibrium constant, Kc, measured as a product and quotient of molar concentrations, is constant at constant temperature. Spectrophotometric measurements of absorbance of a solution of Fe3+(aq) and SCN-(aq) treated with different amounts of KNO3 are made to determine Kc for the formation of FeSCN2+(aq). Students observe a regular decrease in the value of Kc as the concentration of added KNO3 is increased.

Systems with a constant heat flux with applications to radiative heat transport across nanoscale gaps and layers

NASA Astrophysics Data System (ADS)

Budaev, Bair V.; Bogy, David B.

2018-06-01

We extend the statistical analysis of equilibrium systems to systems with a constant heat flux. This extension leads to natural generalizations of Maxwell-Boltzmann's and Planck's equilibrium energy distributions to energy distributions of systems with a net heat flux. This development provides a long needed foundation for addressing problems of nanoscale heat transport by a systematic method based on a few fundamental principles. As an example, we consider the computation of the radiative heat flux between narrowly spaced half-spaces maintained at different temperatures.

Phases, periphases, and interphases equilibrium by molecular modeling. I. Mass equilibrium by the semianalytical stochastic perturbations method and application to a solution between (120) gypsum faces

NASA Astrophysics Data System (ADS)

Pedesseau, Laurent; Jouanna, Paul

2004-12-01

The SASP (semianalytical stochastic perturbations) method is an original mixed macro-nano-approach dedicated to the mass equilibrium of multispecies phases, periphases, and interphases. This general method, applied here to the reflexive relation Ck⇔μk between the concentrations Ck and the chemical potentials μk of k species within a fluid in equilibrium, leads to the distribution of the particles at the atomic scale. The macroaspects of the method, based on analytical Taylor's developments of chemical potentials, are intimately mixed with the nanoaspects of molecular mechanics computations on stochastically perturbed states. This numerical approach, directly linked to definitions, is universal by comparison with current approaches, DLVO Derjaguin-Landau-Verwey-Overbeek, grand canonical Monte Carlo, etc., without any restriction on the number of species, concentrations, or boundary conditions. The determination of the relation Ck⇔μk implies in fact two problems: a direct problem Ck⇒μk and an inverse problem μk⇒Ck. Validation of the method is demonstrated in case studies A and B which treat, respectively, a direct problem and an inverse problem within a free saturated gypsum solution. The flexibility of the method is illustrated in case study C dealing with an inverse problem within a solution interphase, confined between two (120) gypsum faces, remaining in connection with a reference solution. This last inverse problem leads to the mass equilibrium of ions and water molecules within a 3 Å thick gypsum interface. The major unexpected observation is the repulsion of SO42- ions towards the reference solution and the attraction of Ca2+ ions from the reference solution, the concentration being 50 times higher within the interphase as compared to the free solution. The SASP method is today the unique approach able to tackle the simulation of the number and distribution of ions plus water molecules in such extreme confined conditions. This result is of prime importance for all coupled chemical-mechanical problems dealing with interfaces, and more generally for a wide variety of applications such as phase changes, osmotic equilibrium, surface energy, etc., in complex chemical-physics situations.

The effect of restructuring student writing in the general chemistry laboratory on student understanding of chemistry and on students' approach to the laboratory course

NASA Astrophysics Data System (ADS)

Rudd, James Andrew, II

Many students encounter difficulties engaging with laboratory-based instruction, and reviews of research have indicated that the value of such instruction is not clearly evident. Traditional forms of writing associated with laboratory activities are commonly in a style used by professional scientists to communicate developed explanations. Students probably lack the interpretative skills of a professional, and writing in this style may not support students in learning how to develop scientific explanations. The Science Writing Heuristic (SWH) is an inquiry-based approach to laboratory instruction designed in part to promote student ability in developing such explanations. However, there is not a convincing body of evidence for the superiority of inquiry-based laboratory instruction in chemistry. In a series of studies, the performance of students using the SWH student template in place of the standard laboratory report format was compared to the performance of students using the standard format. The standard reports had Title, Purpose, Procedure, Data & Observations, Calculations & Graphs, and Discussion sections. The SWH reports had Beginning Questions & Ideas, Tests & Procedures, Observations, Claims, Evidence, and Reflection sections. The pilot study produced evidence that using the SWH improved the quality of laboratory reports, improved student performance on a laboratory exam, and improved student approach to laboratory work. A main study found that SWH students statistically exhibited a better understanding of physical equilibrium when written explanations and equations were analyzed on a lecture exam and performed descriptively better on a physical equilibrium practical exam task. In another main study, the activities covering the general equilibrium concept were restructured as an additional change, and it was found that SWH students exhibited a better understanding of chemical equilibrium as shown by statistically greater success in overcoming the common confusion of interpreting equilibrium as equal concentrations and by statistically better performance when explaining aspects of chemical equilibrium. Both main studies found that students and instructors spent less time on the SWH reports and that students preferred the SWH approach because it increased their level of mental engagement. The studies supported the conclusion that inquiry-based laboratory instruction benefits student learning and attitudes.

Stochastic thermodynamics

NASA Astrophysics Data System (ADS)

Eichhorn, Ralf; Aurell, Erik

2014-04-01

'Stochastic thermodynamics as a conceptual framework combines the stochastic energetics approach introduced a decade ago by Sekimoto [1] with the idea that entropy can consistently be assigned to a single fluctuating trajectory [2]'. This quote, taken from Udo Seifert's [3] 2008 review, nicely summarizes the basic ideas behind stochastic thermodynamics: for small systems, driven by external forces and in contact with a heat bath at a well-defined temperature, stochastic energetics [4] defines the exchanged work and heat along a single fluctuating trajectory and connects them to changes in the internal (system) energy by an energy balance analogous to the first law of thermodynamics. Additionally, providing a consistent definition of trajectory-wise entropy production gives rise to second-law-like relations and forms the basis for a 'stochastic thermodynamics' along individual fluctuating trajectories. In order to construct meaningful concepts of work, heat and entropy production for single trajectories, their definitions are based on the stochastic equations of motion modeling the physical system of interest. Because of this, they are valid even for systems that are prevented from equilibrating with the thermal environment by external driving forces (or other sources of non-equilibrium). In that way, the central notions of equilibrium thermodynamics, such as heat, work and entropy, are consistently extended to the non-equilibrium realm. In the (non-equilibrium) ensemble, the trajectory-wise quantities acquire distributions. General statements derived within stochastic thermodynamics typically refer to properties of these distributions, and are valid in the non-equilibrium regime even beyond the linear response. The extension of statistical mechanics and of exact thermodynamic statements to the non-equilibrium realm has been discussed from the early days of statistical mechanics more than 100 years ago. This debate culminated in the development of linear response theory for small deviations from equilibrium, in which a general framework is constructed from the analysis of non-equilibrium states close to equilibrium. In a next step, Prigogine and others developed linear irreversible thermodynamics, which establishes relations between transport coefficients and entropy production on a phenomenological level in terms of thermodynamic forces and fluxes. However, beyond the realm of linear response no general theoretical results were available for quite a long time. This situation has changed drastically over the last 20 years with the development of stochastic thermodynamics, revealing that the range of validity of thermodynamic statements can indeed be extended deep into the non-equilibrium regime. Early developments in that direction trace back to the observations of symmetry relations between the probabilities for entropy production and entropy annihilation in non-equilibrium steady states [5-8] (nowadays categorized in the class of so-called detailed fluctuation theorems), and the derivations of the Bochkov-Kuzovlev [9, 10] and Jarzynski relations [11] (which are now classified as so-called integral fluctuation theorems). Apart from its fundamental theoretical interest, the developments in stochastic thermodynamics have experienced an additional boost from the recent experimental progress in fabricating, manipulating, controlling and observing systems on the micro- and nano-scale. These advances are not only of formidable use for probing and monitoring biological processes on the cellular, sub-cellular and molecular level, but even include the realization of a microscopic thermodynamic heat engine [12] or the experimental verification of Landauer's principle in a colloidal system [13]. The scientific program Stochastic Thermodynamics held between 4 and 15 March 2013, and hosted by The Nordic Institute for Theoretical Physics (Nordita), was attended by more than 50 scientists from the Nordic countries and elsewhere, amongst them many leading experts in the field. During the program, the most recent developments, open questions and new ideas in stochastic thermodynamics were presented and discussed. From the talks and debates, the notion of information in stochastic thermodynamics, the fundamental properties of entropy production (rate) in non-equilibrium, the efficiency of small thermodynamic machines and the characteristics of optimal protocols for the applied (cyclic) forces were crystallizing as main themes. Surprisingly, the long-studied adiabatic piston, its peculiarities and its relation to stochastic thermodynamics were also the subject of intense discussions. The comment on the Nordita program Stochastic Thermodynamics published in this issue of Physica Scripta exploits the Jarzynski relation for determining free energy differences in the adiabatic piston. This scientific program and the contribution presented here were made possible by the financial and administrative support of The Nordic Institute for Theoretical Physics.

The length and time scales of water's glass transitions

NASA Astrophysics Data System (ADS)

Limmer, David T.

2014-06-01

Using a general model for the equilibrium dynamics of supercooled liquids, I compute from molecular properties the emergent length and time scales that govern the nonequilibrium relaxation behavior of amorphous ice prepared by rapid cooling. Upon cooling, the liquid water falls out of equilibrium whereby the temperature dependence of its relaxation time is predicted to change from super-Arrhenius to Arrhenius. A consequence of this crossover is that the location of the apparent glass transition temperature depends logarithmically on cooling rate. Accompanying vitrification is the emergence of a dynamical length-scale, the size of which depends on the cooling rate and varies between angstroms and tens of nanometers. While this protocol dependence clarifies a number of previous experimental observations for amorphous ice, the arguments are general and can be extended to other glass forming liquids.

The length and time scales of water's glass transitions.

PubMed

Limmer, David T

2014-06-07

Using a general model for the equilibrium dynamics of supercooled liquids, I compute from molecular properties the emergent length and time scales that govern the nonequilibrium relaxation behavior of amorphous ice prepared by rapid cooling. Upon cooling, the liquid water falls out of equilibrium whereby the temperature dependence of its relaxation time is predicted to change from super-Arrhenius to Arrhenius. A consequence of this crossover is that the location of the apparent glass transition temperature depends logarithmically on cooling rate. Accompanying vitrification is the emergence of a dynamical length-scale, the size of which depends on the cooling rate and varies between angstroms and tens of nanometers. While this protocol dependence clarifies a number of previous experimental observations for amorphous ice, the arguments are general and can be extended to other glass forming liquids.

Predicting the growth of S i3N4 nanowires by phase-equilibrium-dominated vapor-liquid-solid mechanism

NASA Astrophysics Data System (ADS)

Zhang, Yongliang; Cai, Jing; Yang, Lijun; Wu, Qiang; Wang, Xizhang; Hu, Zheng

2017-09-01

Nanomaterial synthesis is experiencing a profound evolution from empirical science ("cook-and-look") to prediction and design, which depends on the deep insight into the growth mechanism. Herein, we report a generalized prediction of the growth of S i3N4 nanowires by nitriding F e28S i72 alloy particles across different phase regions based on our finding of the phase-equilibrium-dominated vapor-liquid-solid (PED-VLS) mechanism. All the predictions about the growth of S i3N4 nanowires, and the associated evolutions of lattice parameters and geometries of the coexisting Fe -Si alloy phases, are experimentally confirmed quantitatively. This progress corroborates the general validity of the PED-VLS mechanism, which could be applied to the design and controllable synthesis of various one-dimensional nanomaterials.

Kolkata Paise Restaurant Problem and the Cyclically Fair Norm

NASA Astrophysics Data System (ADS)

Banerjee, Priyodorshi; Mitra, Manipushpak; Mukherjee, Conan

In this paper we revisit the Kolkata Paise Restaurant problem by allowing for a more general (but common) preference of the n customers defined over the set of n restaurants. This generalization allows for the possibility that each pure strategy Nash equilibrium differs from the Pareto efficient allocation. By assuming that n is small and by allowing for mutual interaction across all customers we design strategies to sustain cyclically fair norm as a sub-game perfect equilibrium of the Kolkata Paise Restaurant problem. We have a cyclically fair norm if n strategically different Pareto efficient strategies are sequentially sustained in a way such that each customer gets serviced in all the n restaurants exactly once between periods 1 and n and then again the same process is repeated between periods (n+1) and 2n and so on.

Equilibrium structure of solar magnetic flux tubes: Energy transport with multistream radiative transfer

NASA Technical Reports Server (NTRS)

Hasan, S. S.; Kalkofen, W.

1994-01-01

We examine the equilibrium structure of vertical intense magnetic flux tubes on the Sun. Assuming cylindrical geometry, we solve the magnetohydrostatic equations in the thin flux-tube approximation, allowing for energy transport by radiation and convection. The radiative transfer equation is solved in the six-stream approximation, assuming gray opacity and local thermodynamic equilibrium. This constitutes a significant improvement over a previous study, in which the transfer was solved using the multidimensional generalization of the Eddington approximation. Convection in the flux tube is treated using mixing-length theory, with an additional parameter alpha, characterizing the suppression of convective energy transport in the tube by the strong magnetic field. The equations are solved using the method of partial linearization. We present results for tubes with different values of the magnetic field strength and radius at a fixed depth in the atmosphere. In general, we find that, at equal geometric heights, the temperature on the tube axis, compared to the ambient medium, is higher in the photosphere and lower in the convection zone, with the difference becoming larger for thicker tubes. At equal optical depths the tubes are generally hotter than their surroundings. The results are comparatively insensitive to alpha but depend upon whether radiative and convective energy transport operate simultaneously or in separate layers. A comparison of our results with semiempirical models shows that the temperature and intensity contrast are in broad agreement. However, the field strengths of the flux-tube models are somewhat lower than the values inferred from observations.

Welfare implications of energy and environmental policies: A general equilibrium approach

NASA Astrophysics Data System (ADS)

Iqbal, Mohammad Qamar

Government intervention and implementation of policies can impose a financial and social cost. To achieve a desired goal there could be several different alternative policies or routes, and government would like to choose the one which imposes the least social costs or/and generates greater social benefits. Therefore, applied welfare economics plays a vital role in public decision making. This paper recasts welfare measure such as equivalent variation, in terms of the prices of factors of production rather than product prices. This is made possible by using duality theory within a general equilibrium framework and by deriving alternative forms of indirect utility functions and expenditure functions in factor prices. Not only we are able to recast existing welfare measures in factor prices, we are able to perform a true cost-benefit analysis of government policies using comparative static analysis of different equilibria and breaking up monetary measure of welfare change such as equivalent variation into its components. A further advantage of our research is demonstrated by incorporating externalities and public goods in the utility function. It is interesting that under a general equilibrium framework optimal income tax tends to reduce inequalities. Results show that imposition of taxes at socially optimal rates brings a net gain to the society. It was also seen that even though a pollution tax may reduce GDP, it leads to an increase in the welfare of the society if it is imposed at an optimal rate.

Stellar equilibrium configurations of compact stars in f ( R , T ) theory of gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moraes, P.H.R.S.; Arbañil, José D.V.; Malheiro, M., E-mail: moraes.phrs@gmail.com, E-mail: arbanil@ita.br, E-mail: malheiro@ita.br

In this article we study the hydrostatic equilibrium configuration of neutron stars and strange stars, whose fluid pressure is computed from the equations of state p =ωρ{sup 5/3} and p =0.28(ρ−4B), respectively, with ω and B being constants and ρ the energy density of the fluid. We start by deriving the hydrostatic equilibrium equation for the f ( R , T ) theory of gravity, with R and T standing for the Ricci scalar and trace of the energy-momentum tensor, respectively. Such an equation is a generalization of the one obtained from general relativity, and the latter can be retrievedmore » for a certain limit of the theory. For the f ( R , T )= R +2λ T functional form, with λ being a constant, we find that some physical properties of the stars, such as pressure, energy density, mass and radius, are affected when λ is changed. We show that for a fixed central star energy density, the mass of neutron and strange stars can increase with λ. Concerning the star radius, it increases for neutron stars and it decreases for strange stars with the increment of λ. Thus, in f ( R , T ) theory of gravity we can push the maximum mass above the observational limits. This implies that the equation of state cannot be eliminated if the maximum mass within General Relativity lies below the limit given by observed pulsars.« less

Stellar equilibrium configurations of compact stars in f(R,T) theory of gravity

NASA Astrophysics Data System (ADS)

Moraes, P. H. R. S.; Arbañil, José D. V.; Malheiro, M.

2016-06-01

In this article we study the hydrostatic equilibrium configuration of neutron stars and strange stars, whose fluid pressure is computed from the equations of state p=ωρ5/3 and p=0.28(ρ-4Script B), respectively, with ω and Script B being constants and ρ the energy density of the fluid. We start by deriving the hydrostatic equilibrium equation for the f(R,T) theory of gravity, with R and T standing for the Ricci scalar and trace of the energy-momentum tensor, respectively. Such an equation is a generalization of the one obtained from general relativity, and the latter can be retrieved for a certain limit of the theory. For the f(R,T)=R+2λ T functional form, with λ being a constant, we find that some physical properties of the stars, such as pressure, energy density, mass and radius, are affected when λ is changed. We show that for a fixed central star energy density, the mass of neutron and strange stars can increase with λ. Concerning the star radius, it increases for neutron stars and it decreases for strange stars with the increment of λ. Thus, in f(R,T) theory of gravity we can push the maximum mass above the observational limits. This implies that the equation of state cannot be eliminated if the maximum mass within General Relativity lies below the limit given by observed pulsars.

Efficient and robust relaxation procedures for multi-component mixtures including phase transition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Ee, E-mail: eehan@math.uni-bremen.de; Hantke, Maren, E-mail: maren.hantke@ovgu.de; Müller, Siegfried, E-mail: mueller@igpm.rwth-aachen.de

We consider a thermodynamic consistent multi-component model in multi-dimensions that is a generalization of the classical two-phase flow model of Baer and Nunziato. The exchange of mass, momentum and energy between the phases is described by additional source terms. Typically these terms are handled by relaxation procedures. Available relaxation procedures suffer from efficiency and robustness resulting in very costly computations that in general only allow for one-dimensional computations. Therefore we focus on the development of new efficient and robust numerical methods for relaxation processes. We derive exact procedures to determine mechanical and thermal equilibrium states. Further we introduce a novelmore » iterative method to treat the mass transfer for a three component mixture. All new procedures can be extended to an arbitrary number of inert ideal gases. We prove existence, uniqueness and physical admissibility of the resulting states and convergence of our new procedures. Efficiency and robustness of the procedures are verified by means of numerical computations in one and two space dimensions. - Highlights: • We develop novel relaxation procedures for a generalized, thermodynamically consistent Baer–Nunziato type model. • Exact procedures for mechanical and thermal relaxation procedures avoid artificial parameters. • Existence, uniqueness and physical admissibility of the equilibrium states are proven for special mixtures. • A novel iterative method for mass transfer is introduced for a three component mixture providing a unique and admissible equilibrium state.« less

The non-equilibrium and energetic cost of sensory adaptation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lan, G.; Sartori, Pablo; Tu, Y.

2011-03-24

Biological sensory systems respond to external signals in short time and adapt to permanent environmental changes over a longer timescale to maintain high sensitivity in widely varying environments. In this work we have shown how all adaptation dynamics are intrinsically non-equilibrium and free energy is dissipated. We show that the dissipated energy is utilized to maintain adaptation accuracy. A universal relation between the energy dissipation and the optimum adaptation accuracy is established by both a general continuum model and a discrete model i n the specific case of the well-known E. coli chemo-sensory adaptation. Our study suggests that cellular levelmore » adaptations are fueled by hydrolysis of high energy biomolecules, such as ATP. The relevance of this work lies on linking the functionality of a biological system (sensory adaptation) with a concept rooted in statistical physics (energy dissipation), by a mathematical law. This has been made possible by identifying a general sensory system with a non-equilibrium steady state (a stationary state in which the probability current is not zero, but its divergence is, see figure), and then numerically and analytically solving the Fokker-Planck and Master Equations which describe the sensory adaptive system. The application of our general results to the case of E. Coli has shed light on why this system uses the high energy SAM molecule to perform adaptation, since using the more common ATP would not suffice to obtain the required adaptation accuracy.« less

Selective gas capture via kinetic trapping

DOE PAGES

Kundu, Joyjit; Pascal, Tod; Prendergast, David; ...

2016-07-13

Conventional approaches to the capture of CO 2 by metal-organic frameworks focus on equilibrium conditions, and frameworks that contain little CO 2 in equilibrium are often rejected as carbon-capture materials. Here we use a statistical mechanical model, parameterized by quantum mechanical data, to suggest that metal-organic frameworks can be used to separate CO 2 from a typical flue gas mixture when used under nonequilibrium conditions. The origin of this selectivity is an emergent gas-separation mechanism that results from the acquisition by different gas types of different mobilities within a crowded framework. The resulting distribution of gas types within the frameworkmore » is in general spatially and dynamically heterogeneous. Our results suggest that relaxing the requirement of equilibrium can substantially increase the parameter space of conditions and materials for which selective gas capture can be effected.« less

Instability of quantum equilibrium in Bohm's dynamics

PubMed Central

Colin, Samuel; Valentini, Antony

2014-01-01

We consider Bohm's second-order dynamics for arbitrary initial conditions in phase space. In principle, Bohm's dynamics allows for ‘extended’ non-equilibrium, with initial momenta not equal to the gradient of phase of the wave function (as well as initial positions whose distribution departs from the Born rule). We show that extended non-equilibrium does not relax in general and is in fact unstable. This is in sharp contrast with de Broglie's first-order dynamics, for which non-standard momenta are not allowed and which shows an efficient relaxation to the Born rule for positions. On this basis, we argue that, while de Broglie's dynamics is a tenable physical theory, Bohm's dynamics is not. In a world governed by Bohm's dynamics, there would be no reason to expect to see an effective quantum theory today (even approximately), in contradiction with observation. PMID:25383020

How the flow affects the phase behaviour and microstructure of polymer nanocomposites.

PubMed

Stephanou, Pavlos S

2015-02-14

We address the issue of flow effects on the phase behaviour of polymer nanocomposite melts by making use of a recently reported Hamiltonian set of evolution equations developed on principles of non-equilibrium thermodynamics. To this end, we calculate the spinodal curve, by computing values for the nanoparticle radius as a function of the polymer radius-of-gyration for which the second derivative of the generalized free energy of the system becomes zero. Under equilibrium conditions, we recover the phase diagram predicted by Mackay et al. [Science 311, 1740 (2006)]. Under non-equilibrium conditions, we account for the extra terms in the free energy due to changes in the conformations of polymer chains by the shear flow. Overall, our model predicts that flow enhances miscibility, since the corresponding miscibility window opens up for non-zero shear rate values.

Thermodynamic parameters for adsorption equilibrium of heavy metals and dyes from wastewaters: Research updated.

PubMed

Chang, Yingju; Lai, Juin-Yih; Lee, Duu-Jong

2016-12-01

The standard Gibbs free energy, enthalpy and entropy change data for adsorption equilibrium reported in biosorption literature during January 2013-May2016 were listed. Since the studied biosorption systems are all near-equilibrium processes, the enthalpy and entropy change data evaluated by fitting temperature-dependent free energy data using van Hoff's equation reveal a compensation artifact. Additional confusion is introduced with arbitrarily chosen adsorbate concentration unit in bulk solution that added free energy change of mixing into the reported free energy and enthalpy change data. Different standard states may be chosen for properly describing biosorption processes; however, this makes the general comparison between data from different systems inappropriate. No conclusion should be drawn based on unjustified thermodynamic parameters reported in biosorption studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

A numerical study of EGS heat extraction process based on a thermal non-equilibrium model for heat transfer in subsurface porous heat reservoir

NASA Astrophysics Data System (ADS)

Chen, Jiliang; Jiang, Fangming

2016-02-01

With a previously developed numerical model, we perform a detailed study of the heat extraction process in enhanced or engineered geothermal system (EGS). This model takes the EGS subsurface heat reservoir as an equivalent porous medium while it considers local thermal non-equilibrium between the rock matrix and the fluid flowing in the fractured rock mass. The application of local thermal non-equilibrium model highlights the temperature-difference heat exchange process occurring in EGS reservoirs, enabling a better understanding of the involved heat extraction process. The simulation results unravel the mechanism of preferential flow or short-circuit flow forming in homogeneously fractured reservoirs of different permeability values. EGS performance, e.g. production temperature and lifetime, is found to be tightly related to the flow pattern in the reservoir. Thermal compensation from rocks surrounding the reservoir contributes little heat to the heat transmission fluid if the operation time of an EGS is shorter than 15 years. We find as well the local thermal equilibrium model generally overestimates EGS performance and for an EGS with better heat exchange conditions in the heat reservoir, the heat extraction process acts more like the local thermal equilibrium process.

Conservative-variable average states for equilibrium gas multi-dimensional fluxes

NASA Technical Reports Server (NTRS)

Iannelli, G. S.

1992-01-01

Modern split component evaluations of the flux vector Jacobians are thoroughly analyzed for equilibrium-gas average-state determinations. It is shown that all such derivations satisfy a fundamental eigenvalue consistency theorem. A conservative-variable average state is then developed for arbitrary equilibrium-gas equations of state and curvilinear-coordinate fluxes. Original expressions for eigenvalues, sound speed, Mach number, and eigenvectors are then determined for a general average Jacobian, and it is shown that the average eigenvalues, Mach number, and eigenvectors may not coincide with their classical pointwise counterparts. A general equilibrium-gas equation of state is then discussed for conservative-variable computational fluid dynamics (CFD) Euler formulations. The associated derivations lead to unique compatibility relations that constrain the pressure Jacobian derivatives. Thereafter, alternative forms for the pressure variation and average sound speed are developed in terms of two average pressure Jacobian derivatives. Significantly, no additional degree of freedom exists in the determination of these two average partial derivatives of pressure. Therefore, they are simultaneously computed exactly without any auxiliary relation, hence without any geometric solution projection or arbitrary scale factors. Several alternative formulations are then compared and key differences highlighted with emphasis on the determination of the pressure variation and average sound speed. The relevant underlying assumptions are identified, including some subtle approximations that are inherently employed in published average-state procedures. Finally, a representative test case is discussed for which an intrinsically exact average state is determined. This exact state is then compared with the predictions of recent methods, and their inherent approximations are appropriately quantified.

Equilibrium Fluctuation Relations for Voltage Coupling in Membrane Proteins

PubMed Central

Kim, Ilsoo; Warshel, Arieh

2015-01-01

A general theoretical framework is developed to account for the effects of an external potential on the energetics of membrane proteins. The framework is based on the free energy relation between two (forward/backward) probability densities, which was recently generalized to non-equilibrium processes, culminating in the work-fluctuation theorem. Starting from the probability densities of the conformational states along the reaction coordinate of “voltage coupling”, we investigate several interconnected free energy relations between these two conformational states, considering voltage activation of ion channels. The free energy difference at zero membrane potential (i.e., between the two “non-equilibrium” conformational states) is shown to be equivalent to the free energy difference between the two “equilibrium” conformational states along the one-dimensional reaction coordinate of voltage coupling. Furthermore, the requirement that the application of linear response approximation to the free energy functions (free energies) of voltage coupling should satisfy the general free energy relations, yields a novel expression for the gating charge in terms of other experimentally measurable quantities. This connection is familiar in statistical mechanics, known as the equilibrium fluctuation-response relation. The theory is illustrated by considering the movement of a unit charge within the membrane under the influence of an external potential, using a coarse-graining (CG) model of membrane proteins, which includes the membrane, the electrolytes and the electrodes. The CG model yields Marcus–type voltage dependent free energy parabolas for the two conformational states, which allow for quantitative estimations of an equilibrium free energy difference, a free energy of barrier, and the voltage dependency of channel activation (Q-V curve) for the unit charge movement. In addition, our analysis offers a quantitative rationale for the correlation between the free energy landscapes (parabolas) and the Q-V curve, upon site-directed mutagenesis or drug binding. Taken together, by introducing the voltage coupling as a reaction coordinate of energy gab, the present theory offers a firm physical foundation from the equilibrium theory of statistical mechanics for the thermodynamic models of voltage activation in voltage-sensitive membrane proteins. This formulation also provides a powerful bridge between the CG model and the conventional macroscopic treatments, offering an intuitive and quantitative framework for a better understating of the structure-function correlations of voltage gating in ion channels as well as electrogenic phenomena in ion pumps and transporters. PMID:26290960

Electric Circuit Model Analogy for Equilibrium Lattice Relaxation in Semiconductor Heterostructures

NASA Astrophysics Data System (ADS)

Kujofsa, Tedi; Ayers, John E.

2018-01-01

The design and analysis of semiconductor strained-layer device structures require an understanding of the equilibrium profiles of strain and dislocations associated with mismatched epitaxy. Although it has been shown that the equilibrium configuration for a general semiconductor strained-layer structure may be found numerically by energy minimization using an appropriate partitioning of the structure into sublayers, such an approach is computationally intense and non-intuitive. We have therefore developed a simple electric circuit model approach for the equilibrium analysis of these structures. In it, each sublayer of an epitaxial stack may be represented by an analogous circuit configuration involving an independent current source, a resistor, an independent voltage source, and an ideal diode. A multilayered structure may be built up by the connection of the appropriate number of these building blocks, and the node voltages in the analogous electric circuit correspond to the equilibrium strains in the original epitaxial structure. This enables analysis using widely accessible circuit simulators, and an intuitive understanding of electric circuits can easily be extended to the relaxation of strained-layer structures. Furthermore, the electrical circuit model may be extended to continuously-graded epitaxial layers by considering the limit as the individual sublayer thicknesses are diminished to zero. In this paper, we describe the mathematical foundation of the electrical circuit model, demonstrate its application to several representative structures involving In x Ga1- x As strained layers on GaAs (001) substrates, and develop its extension to continuously-graded layers. This extension allows the development of analytical expressions for the strain, misfit dislocation density, critical layer thickness and widths of misfit dislocation free zones for a continuously-graded layer having an arbitrary compositional profile. It is similar to the transition from circuit theory, using lumped circuit elements, to electromagnetics, using distributed electrical quantities. We show this development using first principles, but, in a more general sense, Maxwell's equations of electromagnetics could be applied.

Improving the Efficiency of Non-equilibrium Sampling in the Aqueous Environment via Implicit-Solvent Simulations.

PubMed

Liu, Hui; Chen, Fu; Sun, Huiyong; Li, Dan; Hou, Tingjun

2017-04-11

By means of estimators based on non-equilibrium work, equilibrium free energy differences or potentials of mean force (PMFs) of a system of interest can be computed from biased molecular dynamics (MD) simulations. The approach, however, is often plagued by slow conformational sampling and poor convergence, especially when the solvent effects are taken into account. Here, as a possible way to alleviate the problem, several widely used implicit-solvent models, which are derived from the analytic generalized Born (GB) equation and implemented in the AMBER suite of programs, were employed in free energy calculations based on non-equilibrium work and evaluated for their abilities to emulate explicit water. As a test case, pulling MD simulations were carried out on an alanine polypeptide with different solvent models and protocols, followed by comparisons of the reconstructed PMF profiles along the unfolding coordinate. The results show that when employing the non-equilibrium work method, sampling with an implicit-solvent model is several times faster and, more importantly, converges more rapidly than that with explicit water due to reduction of dissipation. Among the assessed GB models, the Neck variants outperform the OBC and HCT variants in terms of accuracy, whereas their computational costs are comparable. In addition, for the best-performing models, the impact of the solvent-accessible surface area (SASA) dependent nonpolar solvation term was also examined. The present study highlights the advantages of implicit-solvent models for non-equilibrium sampling.

Le Chatelier's principle in replicator dynamics

NASA Astrophysics Data System (ADS)

Allahverdyan, Armen E.; Galstyan, Aram

2011-10-01

The Le Chatelier principle states that physical equilibria are not only stable, but they also resist external perturbations via short-time negative-feedback mechanisms: a perturbation induces processes tending to diminish its results. The principle has deep roots, e.g., in thermodynamics it is closely related to the second law and the positivity of the entropy production. Here we study the applicability of the Le Chatelier principle to evolutionary game theory, i.e., to perturbations of a Nash equilibrium within the replicator dynamics. We show that the principle can be reformulated as a majorization relation. This defines a stability notion that generalizes the concept of evolutionary stability. We determine criteria for a Nash equilibrium to satisfy the Le Chatelier principle and relate them to mutualistic interactions (game-theoretical anticoordination) showing in which sense mutualistic replicators can be more stable than (say) competing ones. There are globally stable Nash equilibria, where the Le Chatelier principle is violated even locally: in contrast to the thermodynamic equilibrium a Nash equilibrium can amplify small perturbations, though both types of equilibria satisfy the detailed balance condition.

Le Chatelier's principle in replicator dynamics.

PubMed

Allahverdyan, Armen E; Galstyan, Aram

2011-10-01

The Le Chatelier principle states that physical equilibria are not only stable, but they also resist external perturbations via short-time negative-feedback mechanisms: a perturbation induces processes tending to diminish its results. The principle has deep roots, e.g., in thermodynamics it is closely related to the second law and the positivity of the entropy production. Here we study the applicability of the Le Chatelier principle to evolutionary game theory, i.e., to perturbations of a Nash equilibrium within the replicator dynamics. We show that the principle can be reformulated as a majorization relation. This defines a stability notion that generalizes the concept of evolutionary stability. We determine criteria for a Nash equilibrium to satisfy the Le Chatelier principle and relate them to mutualistic interactions (game-theoretical anticoordination) showing in which sense mutualistic replicators can be more stable than (say) competing ones. There are globally stable Nash equilibria, where the Le Chatelier principle is violated even locally: in contrast to the thermodynamic equilibrium a Nash equilibrium can amplify small perturbations, though both types of equilibria satisfy the detailed balance condition.

Inferring the parameters of a Markov process from snapshots of the steady state

NASA Astrophysics Data System (ADS)

Dettmer, Simon L.; Berg, Johannes

2018-02-01

We seek to infer the parameters of an ergodic Markov process from samples taken independently from the steady state. Our focus is on non-equilibrium processes, where the steady state is not described by the Boltzmann measure, but is generally unknown and hard to compute, which prevents the application of established equilibrium inference methods. We propose a quantity we call propagator likelihood, which takes on the role of the likelihood in equilibrium processes. This propagator likelihood is based on fictitious transitions between those configurations of the system which occur in the samples. The propagator likelihood can be derived by minimising the relative entropy between the empirical distribution and a distribution generated by propagating the empirical distribution forward in time. Maximising the propagator likelihood leads to an efficient reconstruction of the parameters of the underlying model in different systems, both with discrete configurations and with continuous configurations. We apply the method to non-equilibrium models from statistical physics and theoretical biology, including the asymmetric simple exclusion process (ASEP), the kinetic Ising model, and replicator dynamics.

Stability of Poisson Equilibria and Hamiltonian Relative Equilibria by Energy Methods

NASA Astrophysics Data System (ADS)

Patrick, George W.; Roberts, Mark; Wulff, Claudia

2004-12-01

We develop a general stability theory for equilibrium points of Poisson dynamical systems and relative equilibria of Hamiltonian systems with symmetries, including several generalisations of the Energy-Casimir and Energy-Momentum Methods. Using a topological generalisation of Lyapunov’s result that an extremal critical point of a conserved quantity is stable, we show that a Poisson equilibrium is stable if it is an isolated point in the intersection of a level set of a conserved function with a subset of the phase space that is related to the topology of the symplectic leaf space at that point. This criterion is applied to generalise the energy-momentum method to Hamiltonian systems which are invariant under non-compact symmetry groups for which the coadjoint orbit space is not Hausdorff. We also show that a G-stable relative equilibrium satisfies the stronger condition of being A-stable, where A is a specific group-theoretically defined subset of G which contains the momentum isotropy subgroup of the relative equilibrium. The results are illustrated by an application to the stability of a rigid body in an ideal irrotational fluid.

KREEP basalt petrogenesis: Insights from 15434,181

NASA Astrophysics Data System (ADS)

Cronberger, Karl; Neal, Clive R.

2017-05-01

Returned lunar KREEP basalts originated through impact processes or endogenous melting of the lunar interior. Various methods have been used to distinguish between these two origins, with varying degrees of success. Apollo 15 KREEP basalts are generally considered to be endogenous melts of the lunar interior. For example, sample 15434,181 is reported to have formed by a two-stage cooling process, with large orthopyroxene (Opx) phenocrysts forming first and eventually cocrystalizing with smaller plagioclase crystals. However, major and trace element analyses of Opx and plagioclase coupled with calculated equilibrium liquids are inconsistent with the large orthopyroxenes being a phenocryst phase. Equilibrium liquid rare earth element (REE) profiles are enriched relative to the whole rock (WR) composition, inconsistent with Opx being an early crystallizing phase, and these are distinct from the plagioclase REE equilibrium liquids. Fractional crystallization modeling using the Opx equilibrium liquids as a parental composition cannot reproduce the WR values even with crystallization of late-stage phosphates and zircon. This work concludes that instead of being a phenocryst phase, the large Opx crystals are actually xenocrysts that were subsequently affected by pyroxene overgrowths that formed intergrowths with cocrystallizing plagioclase.

A CRDS approach to gas phase equilibrium constants: the case of N 2O 4 ↔ 2NO 2 at 283 K

NASA Astrophysics Data System (ADS)

Tuchler, Matthew F.; Schmidt, Kierstin L.; Morgan, Mackenzie

2005-01-01

We report a general technique for determining the gas phase equilibrium constant, KP, of the A ↔ 2C system using cavity ringdown spectroscopy (CRDS). Working at a constant temperature, the absorption of one of the equilibrium species is measured at two different total pressures. KP is determined from the total pressures of the equilibrium mixture and the ratio of the absorptions. Theoretical limits on sensitivity of this technique are described as a function of experimental conditions. We present results from the reaction N 2O 4 ↔ 2NO 2 measured at T = 283 K. KP measured in this experiment, 21 (±5) Torr, is found to be lower than that recommended by the NASA Panel for Data Evaluation, 32 Torr. [S.P. Sander, A.R. Ravishankara, D.M. Golden, C.E. Kolb, M.J. Kurylo, R.E. Huie, V.L. Orkin, M.J. Molina, G.K. Moortgat, B.J. Finlayson-Pitts, Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies. Evaluation No. 14; Jet Propulsion Laboratory, Pasadena, CA, 2003].

Distance-dependent diffusion-controlled reaction of •NO and O2•- at chemical equilibrium with ONOO-.

PubMed

Botti, Horacio; Möller, Matías N; Steinmann, Daniel; Nauser, Thomas; Koppenol, Willem H; Denicola, Ana; Radi, Rafael

2010-12-16

The fast reaction of (•)NO and O(2)(•-) to give ONOO(-) has been extensively studied at irreversible conditions, but the reasons for the wide variations in observed forward rate constants (3.8 ≤ k(f) ≤ 20 × 10(9) M(-1) s(-1)) remain unexplained. We characterized the diffusion-dependent aqueous (pH > 12) chemical equilibrium of the form (•)NO + O(2)(•-) = ONOO(-) with respect to its dependence on temperature, viscosity, and [ONOO(-)](eq) by determining [ONOO(-)](eq) and [(•)NO](eq). The equilibrium forward reaction rate constant (k(f)(eq)) has negative activation energy, in contrast to that found under irreversible conditions. In contradiction to the law of mass action, we demonstrate that the equilibrium constant depends on ONOO(-) concentration. Therefore, a wide range of k(f)(eq) values could be derived (7.5-21 × 10(9) M(-1) s(-1)). Of general interest, the variations in k(f) can thus be explained by its dependence on the distance between ONOO(-) particles (sites of generation of (•)NO and O(2)(•-)).

Influence of chain topology on polymer crystallization: poly(ethylene oxide) (PEO) rings vs. linear chains.

PubMed

Zardalidis, George; Mars, Julian; Allgaier, Jürgen; Mezger, Markus; Richter, Dieter; Floudas, George

2016-10-04

The absence of entanglements, the more compact structure and the faster diffusion in melts of cyclic poly(ethylene oxide) (PEO) chains have consequences on their crystallization behavior at the lamellar and spherulitic length scales. Rings with molecular weight below the entanglement molecular weight (M < M e ), attain the equilibrium configuration composed from twice-folded chains with a lamellar periodicity that is half of the corresponding linear chains. Rings with M > M e undergo distinct step-like conformational changes to a crystalline lamellar with the equilibrium configuration. Rings melt from this configuration in the absence of crystal thickening in sharp contrast to linear chains. In general, rings more easily attain their extended equilibrium configuration due to strained segments and the absence of entanglements. In addition, rings have a higher equilibrium melting temperature. At the level of the spherulitic superstructure, growth rates are much faster for rings reflecting the faster diffusion and more compact structure. With respect to the segmental dynamics in their semi-crystalline state, ring PEOs with a steepness index of ∼34 form some of the "strongest" glasses.

Nonlinear dynamics of electromagnetic turbulence in a nonuniform magnetized plasma

NASA Astrophysics Data System (ADS)

Shukla, P. K.; Mirza, Arshad M.; Faria, R. T.

1998-03-01

By using the hydrodynamic electron response with fixed (kinetic) ions along with Poisson's equation as well as Ampère's law, a system of nonlinear equations for low-frequency (in comparison with the electron gyrofrequency) long-(short-) wavelength electromagnetic waves in a nonuniform resistive magnetoplasma has been derived. The plasma contains equilibrium density gradient and sheared equilibrium plasma flows. In the linear limit, local dispersion relations are obtained and analyzed. It is found that sheared equilibrium flows can cause instability of Alfvén-like electromagnetic waves even in the absence of a density gradient. Furthermore, it is shown that possible stationary solutions of the nonlinear equations without dissipation can be represented in the form of various types of vortices. On the other hand, the temporal behavior of our nonlinear dissipative systems without the equilibrium density inhomogeneity can be described by the generalized Lorenz equations which admit chaotic trajectories. The density inhomogeneity may lead to even qualitative changes in the chaotic dynamics. The results of our investigation should be useful in understanding the linear and nonlinear properties of nonthermal electromagnetic waves in space and laboratory plasmas.

Bibliography of AV Materials.

ERIC Educational Resources Information Center

Friedstein, Harriet, Ed.

1981-01-01

Lists commercially available audiovisual materials by subject area. Includes title, producer (addresses given), catalog number, format (film, filmstrip, cassette, slides), and prices. Subject areas include: elements; equilibrium; gases; laboratory techniques and experiments; general chemistry; introductory materials (including mathematics); and…

In plane stress analysis

NASA Technical Reports Server (NTRS)

Dillon, O. W., Jr.

1985-01-01

An investigation of the blowing up of UK numerical results for the inplane stress calculations for silicon ribbon is presented. The inplane stress that exists in a thin plate is governed by two general equations of equilibrium and compatibility.

Crystallization of glass-forming liquids: Specific surface energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmelzer, Jürn W. P., E-mail: juern-w.schmelzer@uni-rostock.de; Abyzov, Alexander S.

2016-08-14

A generalization of the Stefan-Skapski-Turnbull relation for the melt-crystal specific interfacial energy is developed in terms of the generalized Gibbs approach extending its standard formulation to thermodynamic non-equilibrium states. With respect to crystal nucleation, this relation is required in order to determine the parameters of the critical crystal clusters being a prerequisite for the computation of the work of critical cluster formation. As one of its consequences, a relation for the dependence of the specific surface energy of critical clusters on temperature and pressure is derived applicable for small and moderate deviations from liquid-crystal macroscopic equilibrium states. Employing the Stefan-Skapski-Turnbullmore » relation, general expressions for the size and the work of formation of critical crystal clusters are formulated. The resulting expressions are much more complex as compared to the respective relations obtained via the classical Gibbs theory. Latter relations are retained as limiting cases of these more general expressions for moderate undercoolings. By this reason, the formulated, here, general relations for the specification of the critical cluster size and the work of critical cluster formation give a key for an appropriate interpretation of a variety of crystallization phenomena occurring at large undercoolings which cannot be understood in terms of the Gibbs’ classical treatment.« less

Actively Shaken In-Situ Passive Sampler Platform for Methylmercury and Organics

DTIC Science & Technology

2016-02-01

Figure 3.2- PRC dissipation and compound uptake kinetics generally assumed for the Performance Reference Compound (PRC) approach...dissipation and compound uptake kinetics generally assumed for the performance reference compound (PRC) approach. C(t) and C(ss) refer to target...under-equilibrated passive sampler measurements that need to be corrected for equilibrium, typically by extrapolation of the loss kinetics of

Hydrostatic equilibrium of stars without electroneutrality constraint

NASA Astrophysics Data System (ADS)

Krivoruchenko, M. I.; Nadyozhin, D. K.; Yudin, A. V.

2018-04-01

The general solution of hydrostatic equilibrium equations for a two-component fluid of ions and electrons without a local electroneutrality constraint is found in the framework of Newtonian gravity theory. In agreement with the Poincaré theorem on analyticity and in the context of Dyson's argument, the general solution is demonstrated to possess a fixed (essential) singularity in the gravitational constant G at G =0 . The regular component of the general solution can be determined by perturbation theory in G starting from a locally neutral solution. The nonperturbative component obtained using the method of Wentzel, Kramers and Brillouin is exponentially small in the inner layers of the star and grows rapidly in the outward direction. Near the surface of the star, both components are comparable in magnitude, and their nonlinear interplay determines the properties of an electro- or ionosphere. The stellar charge varies within the limits of -0.1 to 150 C per solar mass. The properties of electro- and ionospheres are exponentially sensitive to variations of the fluid densities in the central regions of the star. The general solutions of two exactly solvable stellar models without a local electroneutrality constraint are also presented.

Maximum entropy production principle for geostrophic turbulence

NASA Astrophysics Data System (ADS)

Sommeria, J.; Bouchet, F.; Chavanis, P. H.

2003-04-01

In 2D turbulence, complex stirring leads to the formation of steady organized states, once fine scale fluctuations have been filtered out. This self-organization can be explained in terms of statistical equilibrium for vorticity, as the most likely outcome of vorticity parcel rearrangements with the constraints of the conservation laws. A mixing entropy describing the vorticity rearrangements is introduced. Extension to the shallow water system has been proposed by Chavanis P.H. and Sommeria J. (2002), Phys. Rev. E. Generalization to multi-layer geostrophic flows is formally straightforward. Outside equilibrium, eddy fluxes should drive the system toward equilibrium, in the spirit of non equilibrium linear thermodynamics. This can been formalized in terms of a principle of maximum entropy production (MEP), as shown by Robert and Sommeria (1991), Phys. Rev. Lett. 69. Then a parameterization of eddy fluxes is obtained, involving an eddy diffusivity plus a drift term acting at larger scale. These two terms balance each other at equilibrium, resulting in a non trivial steady flow, which is the mean state of the statistical equilibrium. Applications of this eddy parametrization will be presented, in the context of oceanic circulation and Jupiter's Great Red Spot. Quantitative tests will be discussed, obtained by comparisons with direct numerical simulations. Kinetic models, inspired from plasma physics, provide a more precise description of the relaxation toward equilibrium, as shown by Chavanis P.H. 2000 ``Quasilinear theory of the 2D Euler equation'', Phys. Rev. Lett. 84. This approach provides relaxation equations with a form similar to the MEP, but not identical. In conclusion, the MEP provides the right trends of the system but its precise justification remains elusive.

Generalized uncertainty principle and the maximum mass of ideal white dwarfs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rashidi, Reza, E-mail: reza.rashidi@srttu.edu

The effects of a generalized uncertainty principle on the structure of an ideal white dwarf star is investigated. The equation describing the equilibrium configuration of the star is a generalized form of the Lane–Emden equation. It is proved that the star always has a finite size. It is then argued that the maximum mass of such an ideal white dwarf tends to infinity, as opposed to the conventional case where it has a finite value.

Water-stable helical structure of tertiary amides of bicyclic β-amino acid bearing 7-azabicyclo[2.2.1]heptane. Full control of amide cis-trans equilibrium by bridgehead substitution.

PubMed

Hosoya, Masahiro; Otani, Yuko; Kawahata, Masatoshi; Yamaguchi, Kentaro; Ohwada, Tomohiko

2010-10-27

Helical structures of oligomers of non-natural β-amino acids are significantly stabilized by intramolecular hydrogen bonding between main-chain amide moieties in many cases, but the structures are generally susceptible to the environment; that is, helices may unfold in protic solvents such as water. For the generation of non-hydrogen-bonded ordered structures of amides (tertiary amides in most cases), control of cis-trans isomerization is crucial, even though there is only a small sterical difference with respect to cis and trans orientations. We have established methods for synthesis of conformationally constrained β-proline mimics, that is, bridgehead-substituted 7-azabicyclo[2.2.1]heptane-2-endo-carboxylic acids. Our crystallographic, 1D- and 2D-NMR, and CD spectroscopic studies in solution revealed that a bridgehead methoxymethyl substituent completely biased the cis-trans equilibrium to the cis-amide structure along the main chain, and helical structures based on the cis-amide linkage were generated independently of the number of residues, from the minimalist dimer through the tetramer, hexamer, and up to the octamer, and irrespective of the solvent (e.g., water, alcohol, halogenated solvents, and cyclohexane). Generality of the control of the amide equilibrium by bridgehead substitution was also examined.

Climate system properties determining the social cost of carbon

NASA Astrophysics Data System (ADS)

Otto, Alexander; Todd, Benjamin J.; Bowerman, Niel; Frame, David J.; Allen, Myles R.

2013-06-01

The choice of an appropriate scientific target to guide global mitigation efforts is complicated by uncertainties in the temperature response to greenhouse gas emissions. Much climate policy discourse has been based on the equilibrium global mean temperature increase following a concentration stabilization scenario. This is determined by the equilibrium climate sensitivity (ECS) which, in many studies, shows persistent, fat-tailed uncertainty. However, for many purposes, the equilibrium response is less relevant than the transient response. Here, we show that one prominent policy variable, the social cost of carbon (SCC), is generally better constrained by the transient climate response (TCR) than by the ECS. Simple analytic expressions show the SCC to be directly proportional to the TCR under idealized assumptions when the rate at which we discount future damage equals 2.8%. Using ensemble simulations of a simple climate model we find that knowing the true value of the TCR can reduce the relative uncertainty in the SCC substantially more, up to a factor of 3, than knowing the ECS under typical discounting assumptions. We conclude that the TCR, which is better constrained by observations, less subject to fat-tailed uncertainty and more directly related to the SCC, is generally preferable to the ECS as a single proxy for the climate response in SCC calculations.

Fluctuations When Driving Between Nonequilibrium Steady States

NASA Astrophysics Data System (ADS)

Riechers, Paul M.; Crutchfield, James P.

2017-08-01

Maintained by environmental fluxes, biological systems are thermodynamic processes that operate far from equilibrium without detailed-balanced dynamics. Yet, they often exhibit well defined nonequilibrium steady states (NESSs). More importantly, critical thermodynamic functionality arises directly from transitions among their NESSs, driven by environmental switching. Here, we identify the constraints on excess heat and dissipated work necessary to control a system that is kept far from equilibrium by background, uncontrolled "housekeeping" forces. We do this by extending the Crooks fluctuation theorem to transitions among NESSs, without invoking an unphysical dual dynamics. This and corresponding integral fluctuation theorems determine how much work must be expended when controlling systems maintained far from equilibrium. This generalizes thermodynamic feedback control theory, showing that Maxwellian Demons can leverage mesoscopic-state information to take advantage of the excess energetics in NESS transitions. We also generalize an approach recently used to determine the work dissipated when driving between functionally relevant configurations of an active energy-consuming complex system. Altogether, these results highlight universal thermodynamic laws that apply to the accessible degrees of freedom within the effective dynamic at any emergent level of hierarchical organization. By way of illustration, we analyze a voltage-gated sodium ion channel whose molecular conformational dynamics play a critical functional role in propagating action potentials in mammalian neuronal membranes.

The effect of solvent polarity on the accumulation of leachables from pharmaceutical product containers.

PubMed

Jenke, Dennis; Odufu, Alex; Poss, Mitchell

2006-02-01

Material/water equilibrium interaction constants (E(b)) were determined for 12 organic model solutes and a plastic material used in pharmaceutical product containers (non-PVC polyolefin). An excellent correlation was obtained between the measured interaction constants and the organic solute's octanol/water partition coefficient. The effect of solvent polarity on E(b) was assessed by examining the interaction between the plastic and selected model solutes in binary ethanol/water mixtures. In general, logE(b) could be linearily related to the polarity of the ethanol/water mixture. This information, coupled with the interaction model, was used to estimate the levels to which container leachables could accumulate in contacted solutions. Such estimates were made for six known leachables of the polyolefin material and compared to the leachable's measured accumulation levels in binary ethanol/water systems. In general, the accumulation level of the leachables increased with increasing solution polarity. For most of the leachables, the measured accumulation level was less than the calculated levels, suggesting that equilibrium was not achieved in the leaching portion of this study. This lack of equilibrium is attributable to the layered structure of the material studied, as such layering retards the migration of the leachables that are derived from the material's non-solution contact layers.

Liquid–Liquid Equilibrium Measurements for Model Systems Related to Catalytic Fast Pyrolysis of Biomass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jasperson, Louis V.; McDougal, Rubin J.; Diky, Vladimir

Here in this paper we report liquid-liquid mutual solubilities for binary aqueous mixtures involving 2-, 3-, and 4-ethylphenol, 2-, 3-, and 4-methoxyphenol, benzofuran, and 1H-indene for the temperature range (300 < T/K < 360). Measurements in the water-rich phase for (2-ethylphenol + water) were extended to T = 440 K to facilitate comparison with literature values. Liquid-liquid equilibrium tie-line determinations were made for four ternary systems involving (water + toluene) mixed with a third component; phenol, 3-ethylphenol, 4-methoxyphenol, or 2,4-dimethylphenol. Literature values at higher temperatures are available for the three (ethylphenol + water) systems, and, in general, good agreement ismore » seen. The ternary system (water + toluene + phenol) has been studied previously with inconsistent results reported in the literature, and one report is shown to be anomalous. All systems are modeled with the predictive methods NIST-Modified-UNIFAC and NIST-COSMO-SAC, with generally good success in the temperature range of interest (300 < T/K < 360). This work is part of a larger project on the testing and development of predictive phase equilibrium models for compound types occurring in catalytic fast pyrolysis of biomass, and background information for the larger project is provided.« less

Liquid–Liquid Equilibrium Measurements for Model Systems Related to Catalytic Fast Pyrolysis of Biomass

DOE PAGES

Jasperson, Louis V.; McDougal, Rubin J.; Diky, Vladimir; ...

2016-11-02

Here in this paper we report liquid-liquid mutual solubilities for binary aqueous mixtures involving 2-, 3-, and 4-ethylphenol, 2-, 3-, and 4-methoxyphenol, benzofuran, and 1H-indene for the temperature range (300 < T/K < 360). Measurements in the water-rich phase for (2-ethylphenol + water) were extended to T = 440 K to facilitate comparison with literature values. Liquid-liquid equilibrium tie-line determinations were made for four ternary systems involving (water + toluene) mixed with a third component; phenol, 3-ethylphenol, 4-methoxyphenol, or 2,4-dimethylphenol. Literature values at higher temperatures are available for the three (ethylphenol + water) systems, and, in general, good agreement ismore » seen. The ternary system (water + toluene + phenol) has been studied previously with inconsistent results reported in the literature, and one report is shown to be anomalous. All systems are modeled with the predictive methods NIST-Modified-UNIFAC and NIST-COSMO-SAC, with generally good success in the temperature range of interest (300 < T/K < 360). This work is part of a larger project on the testing and development of predictive phase equilibrium models for compound types occurring in catalytic fast pyrolysis of biomass, and background information for the larger project is provided.« less