Microcanonical thermostatistics analysis without histograms: cumulative distribution and Bayesian approaches

Microcanonical thermostatistics analysis has become an important tool to reveal essential aspects of phase transitions in complex systems. An efficient way to estimate the microcanonical inverse temperature $\beta(E)$ and the microcanonical entropy $S(E)$ is achieved with the statistical temperature weighted histogram analysis method (ST-WHAM). The strength of this method lies on its flexibility, as it can be used to analyse data produced by algorithms with generalised sampling weights. However, for any sampling weight, ST-WHAM requires the calculation of derivatives of energy histograms $H(E)$, which leads to non-trivial and tedious binning tasks for models with continuous energy spectrum such as those for biomolecular and colloidal systems. Here, we discuss two alternative methods that avoid the need for such energy binning to obtain continuous estimates for $H(E)$ in order to evaluate $\beta(E)$ by using ST-WHAM: (i) a series expansion to estimate probability densities from the empirical cumulative distribution function (CDF), and (ii) a Bayesian approach to model this CDF. Comparison with a simple linear regression method is also carried out. The performance of these approaches is evaluated considering coarse-grained protein models for folding and peptide aggregation.Comment: 9 pages, 11 figure

Exact solution for the energy density inside a one-dimensional non-static cavity with an arbitrary initial field state

We study the exact solution for the energy density of a real massless scalar field in a two-dimensional spacetime, inside a non-static cavity with an arbitrary initial field state, taking into account the Neumann and Dirichlet boundary conditions. This work generalizes the exact solution proposed by Cole and Schieve in the context of the Dirichlet boundary condition and vacuum as the initial state. We investigate diagonal states, examining the vacuum and thermal field as particular cases. We also study non-diagonal initial field states, taking as examples the coherent and Schrodinger cat states.Comment: 10 pages, 8 figure

Targets and Inflation Dynamics

Brazil has experienced crucial changes in its inflation process since the adoption of inflation targeting in mid 1999. This article addresses changes in the analytical framework employed to track the inflation dynamics, specifically the relevance of an explicit target for inflation. A New-Keynesian Phillips curve (NKPC) is derived incorporating indexation not only to past inflation but also to inflation targets, generalizing the Woodford (2003) hybrid curve. In our modeling, firms that do not optimally set their prices in a given period adjust them only by indexing their previous prices to a weighted average of the inflation target and lagged inflation. In such a framework, the impact of inflation targets on agents' decisions regarding the supply side can be analytically measured by the parameter associated to the inflation target. It is shown that inflation target affects the welfare-based monetary policy objective function by penalizing deviations of actual inflation from target instead of from zero. This result establishes the micro foundation basis for ad-hoc loss functions as indicated in traditional literature. Therefore, the inflation target also affects the optimal target criterion. We also present a microfounded specification to model inflation expectations, and conclude that when firms attribute a high weight to the government's inflation target when setting their own prices, exchange rate and demand shocks are unable to alter significantly inflation expectations. Such a result gives some light to empirical ad hoc assessment conducted in traditional literature. Our empirical evidence shows that even after major shocks, the target ability of anchoring inflation has been restored. Although not formally tested, such a fact followed the monetary authorities' firm commitment to meet the inflation targets, reinforced by the government's necessary support through a consistent fiscal policy.

Is the New Resonance Spin 0 or 2? Taking a Step Forward in the Higgs Boson Discovery

The observation of a new boson of mass \sim 125\gev at the CERN LHC may finally have revealed the existence of a Higgs boson. Now we have the opportunity to scrutinize its properties, determining its quantum numbers and couplings to the standard model particles, in order to confirm or not its discovery. We show that by the end of the 8 TeV run, combining the entire data sets of ATLAS and CMS, it will be possible to discriminate between the following discovery alternatives: a scalar $J^P=0^+$ or a tensor $J^P=2^+$ particle with minimal couplings to photons, at a $5\sigma$ statistical confidence level at least, using only diphotons events. Our results are based on the calculation of a center-edge asymmetry measure of the reconstructed {\it sPlot} scattering polar angle of the diphotons. The results based on asymmetries are shown to be rather robust against systematic uncertainties with comparable discrimination power to a log likelihood ratio statistic.Comment: 11 pages, 6 figures, 1 table. References added, minor typos correcte

Percepción de la salud de los niños expresada en el lenguaje creativo de los dibujos

Objective. Children’s health perception through creative drawing language the identification of external factors perceived as negative or positive to health by children. Methodology. A descriptive study that describes the analysis of the expressive language of drawings and written comments. The sample consisted of 130 children in 3rd and 4th classes from four randomly selected schools, in the region of Central Portugal Continental (Coimbra district). The study was conducted during the first semester of 2011. The data collection was performed by means of Rodrigues’ drawing/writing sheet. This sheet is divided in 4 areas (2 of them to draw what children consider good for health and the other 2 to write the content or message of the drawings). The themes expressed are classified based on the priority areas for the promotion of healthy lifestyles. Results. children value healthy food, physical activity, mental health, prevention of inappropriate substance consumption and health and environment. The drawings and comments show links between diet and physical exercise, and between mental health and interpersonal relationships. Conclusion. Drawings and comments facilitate health professionals understanding of children’s perception of health positive and negative factors. The results of the study allow planning intervention strategies in school health from infant perception

Orion revisited. II. The foreground population to Orion A

Following the recent discovery of a large population of young stars in front of the Orion Nebula, we carried out an observational campaign with the DECam wide-field camera covering ~10~deg^2 centered on NGC 1980 to confirm, probe the extent of, and characterize this foreground population of pre-main-sequence stars. We confirm the presence of a large foreground population towards the Orion A cloud. This population contains several distinct subgroups, including NGC1980 and NGC1981, and stretches across several degrees in front of the Orion A cloud. By comparing the location of their sequence in various color-magnitude diagrams with other clusters, we found a distance and an age of 380pc and 5~10Myr, in good agreement with previous estimates. Our final sample includes 2123 candidate members and is complete from below the hydrogen-burning limit to about 0.3Msun, where the data start to be limited by saturation. Extrapolating the mass function to the high masses, we estimate a total number of ~2600 members in the surveyed region. We confirm the presence of a rich, contiguous, and essentially coeval population of about 2600 foreground stars in front of the Orion A cloud, loosely clustered around NGC1980, NGC1981, and a new group in the foreground of the OMC-2/3. For the area of the cloud surveyed, this result implies that there are more young stars in the foreground population than young stars inside the cloud. Assuming a normal initial mass function, we estimate that between one to a few supernovae must have exploded in the foreground population in the past few million years, close to the surface of Orion A, which might be responsible, together with stellar winds, for the structure and star formation activity in these clouds. This long-overlooked foreground stellar population is of great significance, calling for a revision of the star formation history in this region of the Galaxy.Comment: Accepted for publication in A&