On the number of Mather measures of Lagrangian systems

In 1996, Ricardo Ricardo Ma\~n\'e discovered that Mather measures are in fact the minimizers of a "universal" infinite dimensional linear programming problem. This fundamental result has many applications, one of the most important is to the estimates of the generic number of Mather measures. Ma\~n\'e obtained the first estimation of that sort by using finite dimensional approximations. Recently, we were able with Gonzalo Contreras to use this method of finite dimensional approximation in order to solve a conjecture of John Mather concerning the generic number of Mather measures for families of Lagrangian systems. In the present paper we obtain finer results in that direction by applying directly some classical tools of convex analysis to the infinite dimensional problem. We use a notion of countably rectifiable sets of finite codimension in Banach (and Frechet) spaces which may deserve independent interest

Combination of Growth Model and Earned Schedule to Forecast Project Cost at Completion

To improve the accuracy of early forecasting the final cost at completion of an ongoing construction project, a new regression-based nonlinear cost estimate at completion (CEAC) methodology is proposed that integrates a growth model with earned schedule (ES) concepts. The methodology provides CEAC computations for project early-stage and middle-stage completion. To this end, this paper establishes three primary objectives, as follows: (1) develop a new formula based on integration of the ES method and four candidate growth models (logistic, Gompertz, Bass, andWeibull), (2) validate the new methodology through its application to nine past projects, and (3) select the equation with the best-performing growth model through testing their statistical validity and comparing the accuracy of their CEAC estimates. Based on statistical validity analysis of the four growth models and comparison of CEAC errors, the CEAC formula based on the Gompertz model is better-fitting and generates more accurate final-cost estimates than those computed by using the other three models and the index-based method. The proposed methodology is a theoretical contribution towards the combination of earned-value metrics with regression-based studies. It also brings practical implications associated with usage of a viable and accurate forecasting technique that considers the schedule impact as a determinant factor of cost behavio

Grain boundary motion in layered phases

We study the motion of a grain boundary that separates two sets of mutually perpendicular rolls in Rayleigh-B\'enard convection above onset. The problem is treated either analytically from the corresponding amplitude equations, or numerically by solving the Swift-Hohenberg equation. We find that if the rolls are curved by a slow transversal modulation, a net translation of the boundary follows. We show analytically that although this motion is a nonlinear effect, it occurs in a time scale much shorter than that of the linear relaxation of the curved rolls. The total distance traveled by the boundary scales as $\epsilon^{-1/2}$, where $\epsilon$ is the reduced Rayleigh number. We obtain analytical expressions for the relaxation rate of the modulation and for the time dependent traveling velocity of the boundary, and especially their dependence on wavenumber. The results agree well with direct numerical solutions of the Swift-Hohenberg equation. We finally discuss the implications of our results on the coarsening rate of an ensemble of differently oriented domains in which grain boundary motion through curved rolls is the dominant coarsening mechanism.Comment: 16 pages, 5 figure

Ordering kinetics of stripe patterns

We study domain coarsening of two dimensional stripe patterns by numerically solving the Swift-Hohenberg model of Rayleigh-Benard convection. Near the bifurcation threshold, the evolution of disordered configurations is dominated by grain boundary motion through a background of largely immobile curved stripes. A numerical study of the distribution of local stripe curvatures, of the structure factor of the order parameter, and a finite size scaling analysis of the grain boundary perimeter, suggest that the linear scale of the structure grows as a power law of time with a craracteristic exponent z=3. We interpret theoretically the exponent z=3 from the law of grain boundary motion.Comment: 4 pages, 4 figure

Emergence of Order in Textured Patterns

A characterization of textured patterns, referred to as the disorder function \bar\delta(\beta), is used to study properties of patterns generated in the Swift-Hohenberg equation (SHE). It is shown to be an intensive, configuration-independent measure. The evolution of random initial states under the SHE exhibits two stages of relaxation. The initial phase, where local striped domains emerge from a noisy background, is quantified by a power law decay \bar\delta(\beta) \sim t^{-{1/2} \beta}. Beyond a sharp transition a slower power law decay of \bar\delta(\beta), which corresponds to the coarsening of striped domains, is observed. The transition between the phases advances as the system is driven further from the onset of patterns, and suitable scaling of time and \bar\delta(\beta) leads to the collapse of distinct curves. The decay of $\bar\delta(\beta)$ during the initial phase remains unchanged when nonvariational terms are added to the underlying equations, suggesting the possibility of observing it in experimental systems. In contrast, the rate of relaxation during domain coarsening increases with the coefficient of the nonvariational term.Comment: 9 Pages, 8 Postscript Figures, 3 gif Figure

Pilot Source Study 2015: A Comparison of Performance at Part 121 Regional Airlines Between Pilots Hired Before the U.S. Congress Passed Public Law 111-216 and Pilots Hired After the Law’s Effective Date

This article is the third in a series of reports called Pilot Source Study 2015. In 2010, when the U.S. Congress considered dramatic changes to airline pilot qualifications, researchers from the ‘‘Pilot Source Study 2010’’ sampled pilots from six regional airlines to investigate how pilots’ backgrounds affected their performance in airline training. In 2012, when the FAA proposed rulemaking to implement Public Law 111-216, the ‘‘Pilot Source Study 2012’’ researchers repeated the study with a new sample of pilots from seven different regional airlines. Data from these two studies were combined into a Pre-Law dataset. On August 1, 2013, the mandates of PL 111-216 became effective, ushering in the Post-Law era. The Pilot Source Study 2015 consists of three articles that cover the 19 U.S. regional airlines operating under 14 CFR Part 121. This report (Article 3) compares pilots’ training outcomes between Pre-Law and Post- Law to determine whether their backgrounds had a stronger or weaker influence on Post-Law outcomes. Background variables were segmented into: (a) educational backgrounds, which occur early when pilots obtain their certificates and (b) experience backgrounds, which occur later when pilots accumulate flight time before applying to a regional airline. When comparing the Pre-Law and Post-Law data, educational backgrounds generally had less effect on airline training outcomes. Experience backgrounds also generally had less effect on airline training outcomes, with these exceptions: (a) previous airline and corporate experience had a more positive effect on extra training events, and (b) previous corporate experience had a more positive effect on completions. In conclusion, the congressionally mandated gap between earning pilot certificates and beginning airline training has reduced the positive effects of pilots’ educational and experience backgrounds

Pilot Source Study 2015: A Comparison of Performance at Part 121 Regional Airlines Between Pilots Hired Before the U.S. Congress Passed Public Law 111-216 and Pilots Hired After the Law’s Effective Date

This article is the third in a series of reports called Pilot Source Study 2015. In 2010, when the U.S. Congress considered dramatic changes to airline pilot qualifications, researchers from the ‘‘Pilot Source Study 2010’’ sampled pilots from six regional airlines to investigate how pilots’ backgrounds affected their performance in airline training. In 2012, when the FAA proposed rulemaking to implement Public Law 111-216, the ‘‘Pilot Source Study 2012’’ researchers repeated the study with a new sample of pilots from seven different regional airlines. Data from these two studies were combined into a Pre-Law dataset. On August 1, 2013, the mandates of PL 111-216 became effective, ushering in the Post-Law era. The Pilot Source Study 2015 consists of three articles that cover the 19 U.S. regional airlines operating under 14 CFR Part 121. This report (Article 3) compares pilots’ training outcomes between Pre-Law and Post- Law to determine whether their backgrounds had a stronger or weaker influence on Post-Law outcomes. Background variables were segmented into: (a) educational backgrounds, which occur early when pilots obtain their certificates and (b) experience backgrounds, which occur later when pilots accumulate flight time before applying to a regional airline. When comparing the Pre-Law and Post-Law data, educational backgrounds generally had less effect on airline training outcomes. Experience backgrounds also generally had less effect on airline training outcomes, with these exceptions: (a) previous airline and corporate experience had a more positive effect on extra training events, and (b) previous corporate experience had a more positive effect on completions. In conclusion, the congressionally mandated gap between earning pilot certificates and beginning airline training has reduced the positive effects of pilots’ educational and experience backgrounds

Future Climate and Land Use Change Impacts on River Flows in the Tapajós Basin in the Brazilian Amazon

Abstract Land conversion and changing climate are expected to significantly alter tropical forest hydrology. We used a land surface model integrated with a river routing scheme to analyze the hydrological alterations expected in the Tapajós River basin, a large portion of the Brazilian Amazon, caused by two environmental drivers: climate and land use. The model was forced with two future climate scenarios (years 2026–2045) from the Earth System Model HadGem2‐ES with moderate (+4.5 W/m2 radiative forcing value in the year 2100 with respect to preindustrial levels) and severe (+8.5 W/m2) representative atmospheric carbon dioxide pathways (Representative Concentration Pathways). We tested the sensitivity of our results to the uncertainty in future climate projections by running simulations with IPSL‐CM5 (wettest scenarios) and GISS‐E2 (driest scenarios). Human land use effects on vegetation were evaluated using a limited and an extreme deforestation scenario. Our analysis indicates that climate change is predicted to reduce river flows across seasons (up to 20%) and bring a considerable shift in flow seasonality toward a later onset (nearly 1.5 months) and increase in interannual variability. While land use change partially counteracts the climate‐driven diminishing trend in river flows, it is expected to contribute to a further increase in interannual and intraannual variability. From a water management perspective, the overall reduction of river flows and their increased variability, combined with the shift and the shortening of the wet season, could potentially affect the productivity of the large hydropower systems planned for the region and the growing demand for agricultural and transport expansion

The clinical effectiveness of transurethral incision of the prostate : a systematic review of randomised controlled trials

The original publication is available at www.springerlink.com.Peer reviewedPostprin

On the accuracy of language trees

Historical linguistics aims at inferring the most likely language phylogenetic tree starting from information concerning the evolutionary relatedness of languages. The available information are typically lists of homologous (lexical, phonological, syntactic) features or characters for many different languages. From this perspective the reconstruction of language trees is an example of inverse problems: starting from present, incomplete and often noisy, information, one aims at inferring the most likely past evolutionary history. A fundamental issue in inverse problems is the evaluation of the inference made. A standard way of dealing with this question is to generate data with artificial models in order to have full access to the evolutionary process one is going to infer. This procedure presents an intrinsic limitation: when dealing with real data sets, one typically does not know which model of evolution is the most suitable for them. A possible way out is to compare algorithmic inference with expert classifications. This is the point of view we take here by conducting a thorough survey of the accuracy of reconstruction methods as compared with the Ethnologue expert classifications. We focus in particular on state-of-the-art distance-based methods for phylogeny reconstruction using worldwide linguistic databases. In order to assess the accuracy of the inferred trees we introduce and characterize two generalizations of standard definitions of distances between trees. Based on these scores we quantify the relative performances of the distance-based algorithms considered. Further we quantify how the completeness and the coverage of the available databases affect the accuracy of the reconstruction. Finally we draw some conclusions about where the accuracy of the reconstructions in historical linguistics stands and about the leading directions to improve it.Comment: 36 pages, 14 figure