Association between the perceived environment and physical activity among adults in Latin America: a systematic review

BACKGROUND: Activity friendly environments have been identified as promising strategies to increase physical activity levels in the population. Associations between perceived environmental attributes and physical activity in Latin America may vary from those observed in high income countries. The objective of this systematic review is to identify which perceived environmental attributes are associated with physical activity in Latin America. METHODS: Systematic literature search of articles published in English, Portuguese, and Spanish in four databases was conducted (PubMed, Virtual Health Library, EBSCO, and Web of Science). Associations with environmental attributes were analyzed separately for physical activity domains. Fifteen articles were included in the analysis. RESULTS: All studies had cross-sectional designs. The majority of associations were statistically non-significant, and only four associations were found in the unexpected direction. Leisure-time and transport-related physical activity were the domains most frequently included in the studies and had higher number of associations in the expected direction. Leisure-time physical activity showed a convincing association in the expected direction with safety during the day. Transport-related physical activity had a convincing association with presence of street lighting. CONCLUSIONS: This study shows that perceived environmental attributes and their relationship with physical activity appears to be domain, and context specific. In addition, findings from this study show inconsistencies with the information gathered from high-income countries

Multimessenger study of merging massive black holes in the Obelisk simulation: gravitational waves, electromagnetic counterparts, and their link to galaxy and black hole populations

Massive black hole (BH) mergers are predicted to be powerful sources of low-frequency gravitational waves (GWs). Coupling the detection of GWs with electromagnetic (EM) detection can provide key information about merging BHs and their environments. We study the high-resolution cosmological radiation-hydrodynamics simulation Obelisk, run to redshift $z=3.5$, to assess the GW and EM detectability of high-redshift BH mergers, modelling spectral energy distribution and obscuration. For EM detectability we further consider sub-grid dynamical delays in postprocessing. We find that most of the merger events can be detected by LISA, except for high-mass mergers with very unequal mass ratios. Intrinsic binary parameters are accurately measured, but the sky localisation is poor generally. Only $\sim 40\%$ of these high-redshift sources have sky localisation better than $10\,\mathrm{deg}^2$. Merging BHs are hard to detect in the restframe UV since they are fainter than the host galaxies, which at high $z$ are star-forming. A significant fraction, $15-35\%$, of BH mergers instead outshines the galaxy in X-rays, and about $5-15\%$ are sufficiently bright to be detected with sensitive X-ray instruments. If mergers induce an Eddington-limited brightening, up to $30\%$ of sources can become observable. The transient flux change originating from such a brightening is often large, allowing $4-20\%$ of mergers to be detected as EM counterparts. A fraction $1-30\%$ of mergers is also detectable at radio frequencies. Observable merging BHs tend to have higher accretion rates and masses and are overmassive at fixed galaxy mass with respect to the full population. Most EM-observable mergers can also be GW-detected with LISA, but their sky localisation is generally poorer. This has to be considered when using EM counterparts to obtain information about the properties of merging BHs and their environment.Comment: 17 pages, 11 figures, submitted to A&

Population statistics of intermediate mass black holes in dwarf galaxies using the NewHorizon simulation

While it is well established that supermassive black holes (SMBHs) co-evolve with their host galaxy, it is currently less clear how lower mass black holes, so-called intermediate mass black holes (IMBHs), evolve within their dwarf galaxy hosts. In this paper, we present results on the evolution of a large sample of IMBHs from the NewHorizon simulation. We show that occupation fractions of IMBHs in dwarf galaxies are at least 50 percent for galaxies with stellar masses down to 1E6 Msun, but BH growth is very limited in dwarf galaxies. In NewHorizon, IMBH growth is somewhat more efficient at high redshift z = 3 but in general IMBH do not grow significantly until their host galaxy leaves the dwarf regime. As a result, NewHorizon under-predicts observed AGN luminosity function and AGN fractions. We show that the difficulties of IMBH to remain attached to the centres of their host galaxies plays an important role in limiting their mass growth, and that this dynamic evolution away from galactic centres becomes stronger at lower redshift.Comment: 15 pages, submitted to MNRA

Robust signatures in the current-voltage characteristics of DNA molecules oriented between two graphene nanoribbon electrodes

In this work we numerically calculate the electric current through three kinds of DNA sequences (telomeric, \lambda-DNA, and p53-DNA) described by different heuristic models. A bias voltage is applied between two zig-zag edged graphene contacts attached to the DNA segments, while a gate terminal modulates the conductance of the molecule. The calculation of current is performed by integrating the transmission function (calculated using the lattice Green's function) over the range of energies allowed by the chemical potentials. We show that a telomeric DNA sequence, when treated as a quantum wire in the fully coherent low-temperature regime, works as an excellent semiconductor. Clear steps are apparent in the current-voltage curves of telomeric sequences and are present independent of lengths and sequence initialisation at the contacts. The current-voltage curves suggest the existence of stepped structures independent of length and sequencing initialisation at the contacts. We also find that the molecule-electrode coupling can drastically influence the magnitude of the current. The difference between telomeric DNA and other DNA, such as \lambda-DNA and DNA for the tumour suppressor p53, is particularly visible in the length dependence of the current

A simulational and theoretical study of the spherical electrical double layer for a size-asymmetric electrolyte: the case of big coions

Monte Carlo simulations of a spherical macroion, surrounded by a size-asymmetric electrolyte in the primitive model, were performed. We considered 1:1 and 2:2 salts with a size ratio of 2 (i.e., with coions twice the size of counterions), for several surface charge densities of the macrosphere. The radial distribution functions, electrostatic potential at the Helmholtz surfaces, and integrated charge are reported. We compare these simulational data with original results obtained from the Ornstein-Zernike integral equation, supplemented by the hypernetted chain/hypernetted chain (HNC/HNC) and hypernetted chain/mean spherical approximation (HNC/MSA) closures, and with the corresponding calculations using the modified Gouy-Chapman and unequal-radius modified Gouy-Chapman theories. The HNC/HNC and HNC/MSA integral equations formalisms show good concordance with Monte Carlo "experiments", whereas the notable limitations of point-ion approaches are evidenced. Most importantly, the simulations confirm our previous theoretical predictions of the non-dominance of the counterions in the size-asymmetric spherical electrical double layer [J. Chem. Phys. 123, 034703 (2005)], the appearance of anomalous curvatures at the outer Helmholtz plane and the enhancement of charge reversal and screening at high colloidal surface charge densities due to the ionic size asymmetry.Comment: 11 pages, 7 figure

Electronic transport across linear defects in graphene

We investigate the low-energy electronic transport across grain boundaries in graphene ribbons and infinite flakes. Using the recursive Green’s function method, we calculate the electronic transmission across different types of grain boundaries in graphene ribbons. We show results for the charge density distribution and the current flow along the ribbon. We study linear defects at various angles with the ribbon direction, as well as overlaps of two monolayer ribbon domains forming a bilayer region. For a class of extended defect lines with periodicity 3, an analytic approach is developed to study transport in infinite flakes. This class of extended grain boundaries is particularly interesting, since the K and K0 Dirac points are superposed.NMRP acknowledges support from EC under Graphene Flagship (Contract No. CNECT-ICT-604391) and the hospitality of the Instituto de Física of the UFRJ, where this work was completed. JNBR acknowledges Singapore National Research Foundation for its support through the Fellowship Program NRFNRFF2012-01. CJP and ALCP acknowledge So Paulo Research Foundation (FAPESP), grant 2012/19060-0. Part of the numerical simulations were performed at the computational facilities from CENAPAD-SP, at Campinas State University

Nivel de sesgos cognitivos de representatividad y confirmación en estudiantes de Psicología de tres universidades del Bío-Bío

Cognitive biases are unreasonable ways of making decisions, often in a one-sided way. The objective of this research was to describe the level of representativeness and confirmation biases in Chilean psychology students, in order to know how this phenomenon occurs. The participants were 198 psychology students from three universities in southern Chile. The instrument was based on two cognitive tasks derived from Kanheman and Tversky. The data were analyzed through descriptive statistics and mean differences. The results indicate a high level of biases in the groups of students, in the two tasks evaluated; the representativeness bias presents differences among universities only in sub-task 1, as well as in task 2, related to confirmation bias. Likewise, there are differences in representation bias according to age and sex. The need to strengthen reasoning skills in the initial training of future psychologists, in order to improve skills related to decision making in the professional field is concluded.Los sesgos cognitivos son formas no razonadas de tomar decisiones, a menudo de manera parcializada. El objetivo de esta investigación fue describir el nivel de sesgos de representatividad y confirmación en estudiantes de psicología chilenos, para conocer cómo se presenta este fenómeno. Los participantes fueron 198 estudiantes de psicología, de tres universidades del sur de Chile. El instrumento se basó en dos tareas cognitivas derivadas de Kanheman y Tversky; se analizaron los datos con estadística descriptiva y diferencias de medias. Los resultados indican alto nivel de sesgos en los grupos de estudiantes, en las dos tareas evaluadas; el sesgo de representatividad presenta diferencias entre universidades, solo en la subtarea 1, así como en la tarea 2, relacionada con sesgo de confirmación; así mismo se observan diferencias en sesgo de representación según edad y sexo. Se concluye la necesidad de fortalecer habilidades de razonamiento en la formación inicial de los futuros psicólogos y psicólogas, con la finalidad de mejorar las habilidades relacionadas con la toma de decisiones en el campo profesional

Nivel de sesgos cognitivos de representatividad y confirmación en estudiantes de Psicología de tres universidades del Bío-Bío

Cognitive biases are unreasonable ways of making decisions, often in a one-sided way. The objective of this research was to describe the level of representativeness and confirmation biases in Chilean psychology students, in order to know how this phenomenon occurs. The participants were 198 psychology students from three universities in southern Chile. The instrument was based on two cognitive tasks derived from Kanheman and Tversky. The data were analyzed through descriptive statistics and mean differences. The results indicate a high level of biases in the groups of students, in the two tasks evaluated; the representativeness bias presents differences among universities only in sub-task 1, as well as in task 2, related to confirmation bias. Likewise, there are differences in representation bias according to age and sex. The need to strengthen reasoning skills in the initial training of future psychologists, in order to improve skills related to decision making in the professional field is concluded.Los sesgos cognitivos son formas no razonadas de tomar decisiones, a menudo de manera parcializada. El objetivo de esta investigación fue describir el nivel de sesgos de representatividad y confirmación en estudiantes de psicología chilenos, para conocer cómo se presenta este fenómeno. Los participantes fueron 198 estudiantes de psicología, de tres universidades del sur de Chile. El instrumento se basó en dos tareas cognitivas derivadas de Kanheman y Tversky; se analizaron los datos con estadística descriptiva y diferencias de medias. Los resultados indican alto nivel de sesgos en los grupos de estudiantes, en las dos tareas evaluadas; el sesgo de representatividad presenta diferencias entre universidades, solo en la subtarea 1, así como en la tarea 2, relacionada con sesgo de confirmación; así mismo se observan diferencias en sesgo de representación según edad y sexo. Se concluye la necesidad de fortalecer habilidades de razonamiento en la formación inicial de los futuros psicólogos y psicólogas, con la finalidad de mejorar las habilidades relacionadas con la toma de decisiones en el campo profesional

Electronic localization at mesoscopic length scales: different definitions of localization and contact effects in a heuristic DNA model

In this work we investigate the electronic transport along model DNA molecules using an effective tight-binding approach that includes the backbone on site energies. The localization length and participation number are examined as a function of system size, energy dependence, and the contact coupling between the leads and the DNA molecule. On one hand, the transition from an diffusive regime to a localized regime for short systems is identified, suggesting the necessity of a further length scale revealing the system borders sensibility. On the other hand, we show that the lenght localization and participation number, do not depended of system size and contact coupling in the thermodynamic limit. Finally we discuss possible length dependent origins for the large discrepancies among experimental results for the electronic transport in DNA sample

Social representations of history, wars and politics in Latin America, Europe and Africa

This study analyzes how people perceive world history on three continents: Latin America, Europe and Africa. A total of 1179 university students form Argentina, Brazil, Peru, Portugal, Spain, Guinea-Bissau, and Cape Verde were asked to evaluate world events and leaders in terms of their valence and importance. The results demonstrated that social representations of history show a Euro/North American-centric, long-term positive evaluation, recency, and socio- centric bias. Euro/North American-centric events and leaders were found to be rated as more important and were more positively perceived in general. Distant political events, like French or American Revolution, were considered to be more positive than XX century similar events, which supports the long-term positive evaluation bias hypothesis. The hypothesis on recency bias was partially substantiated. Confirming the existence of such bias, World War II was rated as more important than the previous XX century wars and revolutions. Socio-centric bias also received partial support. African participants rated Mandela as a more important leader than other participants did. Latin Americans rated Che Guevara less positively, which suggests that some leaders are generally idealized icons, not based on group belongingness. However, results did not bring support to the centrality of war hypothesis. Wars were indeed negatively evaluated and World War II was rated as an important and negative event. Nevertheless, war- and politics-related events were not perceived as more important than the Industrial Revolution, suggesting that people appraise the importance of long-term socioeconomic factors of history when responding to close-ended quantitative measures (vs. open-ended salience measures). Results are discussed in the framework of social representations of history.El estudio analiza como las personas perciben la historia mundial en tres continentes: Latinoamérica, Europa y África. 1179 estudiantes universitarios de Argentina, Brasil, Perú, Portugal, España, Guinea-Bissau y Cabo Verde evaluaron una lista de eventos mundiales y líderes en lo que concierne a su valoración e importancia. Los resultados han mostrado que la representación social de la historia se caracteriza por un Euro centrismo, una evaluación positiva a largo plazo, y por sesgos socio-céntricos. Los eventos “Occidentales” (vinculados a Europa y Norteamérica) fueron evaluados como más importantes y percibidos más positivamente que los no-Occidentales. Eventos políticos distantes, como la Revolución Francesa o Americana, fueron evaluados más positivamente que eventos similares del siglo XX, apoyando la hipótesis de la evaluación positiva del pasado lejano. La hipótesis del sesgo de recencia o proximidad fue parcialmente confirmada, ya que la II Guerra Mundial fue evaluada como más importante que revoluciones o guerras anteriores al siglo XX. El sesgo socio-céntrico también recibe apoyo parcial. Los africanos consideraron a Mandela como un líder más importante comparado con los otros participantes. Los Latinos americanos evaluaron Che Guevara menos positivamente, lo que sugiere que ciertos líderes son generalmente íconos idealizados, y su valoración positiva no se basa en la proximidad o la pertenencia grupal. Sin embargo, los resultados no apoyaron la hipótesis de la centralidad de la guerra. Las guerras fueron efectivamente evaluadas negativamente y la II Guerra Mundial fue evaluado como la guerra más importante y como un evento muy negativo. No obstante, las guerras y eventos políticos relacionados con la violencia no fueron percibidos como más importantes que la Revolución industrial, sugiriendo que las personas valoran la importancia general de los factores históricos socioeconómicos cuando responden a medidas cuantitativas cerradas (vs. medidas abiertas). Los resultados se analizan desde el marco teórico de las representaciones sociales de la Historia