Near mean-field behavior in the generalized Burridge-Knopoff earthquake model with variable range stress transfer

Simple models of earthquake faults are important for understanding the mechanisms for their observed behavior in nature, such as Gutenberg-Richter scaling. Because of the importance of long-range interactions in an elastic medium, we generalize the Burridge-Knopoff slider-block model to include variable range stress transfer. We find that the Burridge-Knopoff model with long-range stress transfer exhibits qualitatively different behavior than the corresponding long-range cellular automata models and the usual Burridge-Knopoff model with nearest-neighbor stress transfer, depending on how quickly the friction force weakens with increasing velocity. Extensive simulations of quasiperiodic characteristic events, mode-switching phenomena, ergodicity, and waiting-time distributions are also discussed. Our results are consistent with the existence of a mean-field critical point and have important implications for our understanding of earthquakes and other driven dissipative systems.Comment: 24 pages 12 figures, revised version for Phys. Rev.

Gas phase reaction rates of some positive ions with water at 296 K

Measuring rate constants for reactions of various gas phases with water by flowing afterglow techniqu

China's Economic Reforms: Chronology and Statistics

At the end of the twentieth century, the People's Republic of China faces stark trade policy choices. Market reforms implemented since 1978 have brought commercial strength and bright expectations for future prosperity. However, they have also brought China to the point where trading partners insist on commitments to liberal, internationally recognized trading principles. These calls come at a time when China is seeking to enter the World Trade Organization (WTO), is negotiating bilateral trade agreements with Europe, United States and its emerging neighbors, and is working out the terms of its participation in the ambitious Asia Pacific Economic Cooperation (APEC) forum.

Kinetics and mechanism of the formation of water cluster ions from O2(plus) and H2O in He, Ar, N2, and O2 at 296 K

The reaction sequence leading from O2(+) to H3O(+)-H2O was examined in He, Ar, N2 and O2 carrier gases in a flowing afterglow system. The rate constants for the reactions were measured and the kinetic analysis for their determination is presented. For M = N2, two new steps involving the formation and reaction of O2(+)-N2 were proposed and examined. The rate constants are discussed and compared with other experimental values

Charged Higgs bosons from the 3-3-1 models and the R(D(∗))\mathcal{R}(D^{(*)}) anomalies

Several anomalies in the semileptonic B-meson decays such as $\mathcal{R}(D^{(*)})$ have been reported by $BABAR$, Belle, and LHCb collaborations recently. In this paper, we investigate the contributions of the charged Higgs bosons from the 3-3-1 models to the $\mathcal{R}(D^{(*)})$ anomalies. We find that, in a wide range of parameter space, the 3-3-1 models might give reasonable explanations to the $\mathcal{R}(D^{(*)})$ anomalies and other analogous anomalies of the B meson's semileptonic decays.Comment: Accpeted by Physical Review

A systematic review of the effects of dietary interventions on neonatal outcomes in adolescent pregnancy

© 2015 The Royal College of Midwives. Background. Poor nutrition negatively impacts on pregnancy outcome, fetal growth and neonatal survival. Adolescent mothers, with competing demands of a growing baby and their own rising nutritional requirements, often have poor diets. Despite recognition of their physiological immaturity and nutritional inadequacies, along with evidence highlighting significant differences between adolescent and adult pregnancy outcomes, systematic evidence on the effects of supplementation on adolescent pregnancy is scarce. Aim. To evaluate the effectiveness of dietary interventions on neonatal outcomes in adolescent pregnancy (19 and under). Method. CENTRAL, EMBASE, CINAHL, Cochrane, Maternity and Infant Care, Scopus and MEDLINE databases were searched using selected terminology. Titles and abstracts were screened with selected papers reviewed in full by two authors against the inclusion criteria. Any randomised controlled trials in which the effects of nutritional interventions were evaluated in adolescent pregnancy were included. Data were extracted on study quality, design, compliance, dose and duration of intervention, and main birth outcomes, and analysed using Review Manager. Results. Five studies out of 18 identified were included. Four used supplementation (three zinc, one calcium) with one intervention comparing dairy products to fortified orange juice. The limited available data showed a significant effect from zinc supplementation in reducing the likelihood of low birthweight (RR [95%CI]: 0.39 [0.15, 0.98], one study, n=507) and that having four servings of dairy per day increased average birthweight in adolescent pregnancy (MD [95%CI]: 240g [110.83, 369.17]). Conclusion. High-quality comparative studies between supplements and food sources to improve birth outcomes for adolescent pregnancies, focusing on the clinical effectiveness and acceptability are urgently needed

Comparing Complex Fitness Surfaces: Among-Population Variation in Mutual Sexual Selection in Drosophila serrata

The problem of synchronization of metacommunities is investigated in this article with reference to a rather general model composed of a chaotic environmental compartment driving a biological compartment. Synchronization in the absence of dispersal (i.e., the so-called Moran effect) is first discussed and shown to occur only when there is no biochaos. In other words, if the biological compartment is reinforcing environmental chaos, dispersal must be strictly above a specified threshold in order to synchronize population dynamics. Moreover, this threshold can be easily determined from the model by computing a special Lyapunov exponent. The application to prey-predator metacommunities points out the influence of frequency and coherence of the environmental noise on synchronization and agrees with all experimental studies performed on the subject

Genetic Constraints and the Evolution of Display Trait Sexual Dimorphism by Natural and Sexual Selection.

The evolution of sexual dimorphism involves an interaction between sex-specific selection and a breakdown of genetic constraints that arise because the two sexes share a genome. We examined genetic constraints and the effect of sex-specific selection on a suite of sexually dimorphic display traits in Drosophila serrata. Sexual dimorphism varied among nine natural populations covering a substantial portion of the species range. Quantitative genetic analyses showed that intersexual genetic correlations were high because of autosomal genetic variance but that the inclusion of X-linked effects reduced genetic correlations substantially, indicating that sex linkage may be an important mechanism by which intersexual genetic constraints are reduced in this species. We then explored the potential for both natural and sexual selection to influence these traits, using a 12-generation laboratory experiment in which we altered the opportunities for each process as flies adapted to a novel environment. Sexual dimorphism evolved, with natural selection reducing sexual dimorphism, whereas sexual selection tended to increase it overall. To this extent, our results are consistent with the hypothesis that sexual selection favors evolutionary divergence of the sexes. However, sex-specific responses to natural and sexual selection contrasted with the classic model because sexual selection affected females rather than males