On the Impact of Fair Best Response Dynamics

In this work we completely characterize how the frequency with which each player participates in the game dynamics affects the possibility of reaching efficient states, i.e., states with an approximation ratio within a constant factor from the price of anarchy, within a polynomially bounded number of best responses. We focus on the well known class of congestion games and we show that, if each player is allowed to play at least once and at most $\beta$ times any $T$ best responses, states with approximation ratio $O(\beta)$ times the price of anarchy are reached after $T \lceil \log \log n \rceil$ best responses, and that such a bound is essentially tight also after exponentially many ones. One important consequence of our result is that the fairness among players is a necessary and sufficient condition for guaranteeing a fast convergence to efficient states. This answers the important question of the maximum order of $\beta$ needed to fast obtain efficient states, left open by [9,10] and [3], in which fast convergence for constant $\beta$ and very slow convergence for $\beta=O(n)$ have been shown, respectively. Finally, we show that the structure of the game implicitly affects its performances. In particular, we show that in the symmetric setting, in which all players share the same set of strategies, the game always converges to an efficient state after a polynomial number of best responses, regardless of the frequency each player moves with

A selected history of expectation bias in physics

The beliefs of physicists can bias their results towards their expectations in a number of ways. We survey a variety of historical cases of expectation bias in observations, experiments, and calculations.Comment: 6 pages, 2 figure

Improving Approximate Pure Nash Equilibria in Congestion Games

Congestion games constitute an important class of games to model resource allocation by different users. As computing an exact or even an approximate pure Nash equilibrium is in general PLS-complete, Caragiannis et al. (2011) present a polynomial-time algorithm that computes a ($2 + \epsilon$)-approximate pure Nash equilibria for games with linear cost functions and further results for polynomial cost functions. We show that this factor can be improved to $(1.61+\epsilon)$ and further improved results for polynomial cost functions, by a seemingly simple modification to their algorithm by allowing for the cost functions used during the best response dynamics be different from the overall objective function. Interestingly, our modification to the algorithm also extends to efficiently computing improved approximate pure Nash equilibria in games with arbitrary non-decreasing resource cost functions. Additionally, our analysis exhibits an interesting method to optimally compute universal load dependent taxes and using linear programming duality prove tight bounds on PoA under universal taxation, e.g, 2.012 for linear congestion games and further results for polynomial cost functions. Although our approach yield weaker results than that in Bil\`{o} and Vinci (2016), we remark that our cost functions are locally computable and in contrast to Bil\`{o} and Vinci (2016) are independent of the actual instance of the game

On Linear Congestion Games with Altruistic Social Context

We study the issues of existence and inefficiency of pure Nash equilibria in linear congestion games with altruistic social context, in the spirit of the model recently proposed by de Keijzer {\em et al.} \cite{DSAB13}. In such a framework, given a real matrix $\Gamma=(\gamma_{ij})$ specifying a particular social context, each player $i$ aims at optimizing a linear combination of the payoffs of all the players in the game, where, for each player $j$, the multiplicative coefficient is given by the value $\gamma_{ij}$. We give a broad characterization of the social contexts for which pure Nash equilibria are always guaranteed to exist and provide tight or almost tight bounds on their prices of anarchy and stability. In some of the considered cases, our achievements either improve or extend results previously known in the literature

Caracterização físico-química e reológicas da polpa de cupuaçu congelada (Theobroma grandiflorum Schum).

Cupuaçu, uma das principais e mais consumidas frutas da região amazônica brasileira, pertence à família Sterculiacea, cuja denominação binomial é Theobroma grandiflorum schum. É uma fruta típica da Amazônia, sendo cultivada nos estados do Pará, Maranhão e Tocantins. Esta fruta apresenta crescente utilização no Brasil para o mercado interno e externo, sendo comumente comercializada como polpa congelada. Apesar de sua importância, há poucos dados de caracterização e contaminação da polpa de cupuaçu. Amostras de polpa de cupuaçu foram avaliadas quanto à viscosidade aparente, tensão de cisalhamento, umidade, cinzas, nitrogênio total, extrato etéreo, acidez, sólidos solúveis e pH. Os resultados demonstram a necessidade de aprimorar as boas práticas agrícolas e de fabricação e implantação de sistemas de controle de qualidade para minimização dos riscos associados à contaminação por micro-organismos

Space and Ground Based Pulsation Data of Eta Bootis Explained with Stellar Models Including Turbulence

The space telescope MOST is now providing us with extremely accurate low frequency p-mode oscillation data for the star Eta Boo. We demonstrate in this paper that these data, when combined with ground based measurements of the high frequency p-mode spectrum, can be reproduced with stellar models that include the effects of turbulence in their outer layers. Without turbulence, the l=0 modes of our models deviate from either the ground based or the space data by about 1.5-4.0 micro Hz. This discrepancy can be completely removed by including turbulence in the models and we can exactly match 12 out of 13 MOST frequencies that we identified as l=0 modes in addition to 13 out of 21 ground based frequencies within their observational 2 sigma tolerances. The better agreement between model frequencies and observed ones depends for the most part on the turbulent kinetic energy which was taken from a 3D convection simulation for the Sun.Comment: 13 pages, 7 figures, ApJ in pres

Relationship between quantum decoherence times and solvation dynamics in condensed phase chemical systems

A relationship between the time scales of quantum coherence loss and short-time solvent response for a solute/bath system is derived for a Gaussian wave packet approximation for the bath. Decoherence and solvent response times are shown to be directly proportional to each other, with the proportionality coefficient given by the ratio of the thermal energy fluctuations to the fluctuations in the system-bath coupling. The relationship allows the prediction of decoherence times for condensed phase chemical systems from well developed experimental methods.Comment: 10 pages, no figures, late

Does working memory training improve dietary self-care in type 2 diabetes mellitus? Results of a double blind randomised controlled trial

Aims: Controlling food intake despite adequate knowledge remains a struggle for many people with type 2 diabetes. The present study investigated whether working memory training can reduce food intake and improve glycaemic control. It also examined training effects on cognition, food cravings, and dietary self-efficacy and self-care. Methods: In a double-blind multicentre parallel-group randomised controlled trial, adults with type 2 diabetes mellitus were randomly allocated to receive 25 sessions of either active (n = 45) or control (n = 36) working memory training. Assessments at baseline, post-training and 3-month follow-up measured cognition, food intake (primary outcomes), glycaemic control (HbA1c) and cholesterol (secondary outcomes). Semi-structured interviews assessed participants’ experiences of the training. Results: Intention-to-treat ANOVAs (N = 81) showed improved non-trained updating ability in active compared to control training from pre-test (active M = 34.37, control M = 32.79) to post-test (active M = 31.35, control M = 33.53) and follow-up (active M = 31.81, control M = 32.65; g2 = 0.05). There were no overall effects of training on other measures of cognition, food intake, HbA1c, cholesterol, food cravings and dietary self-efficacy and self-care. In post-hoc analyses, those high in dietary restraint in the active training group showed a greater reduction in fat intake pre to post-test compared to controls. Interviews revealed issues around acceptability and performance of the training. Conclusions: Transfer of working memory training effects to non-trained behaviour were limited, but do suggest that training may reduce fat intake in those who are already motivated to do so. Trial registration: Current Controlled Trials ISRCTN22806944