LA INVESTIGACIÓN EN LA COTIDIANIDAD SOCIAL DESDE LA FENOMENOLOGÍA

Este artículo presenta algunas reflexiones sobre la importancia de dar un lugar preeminente a los actores, cuando de lo que se trata es de investigar la cotidianidad social. Se valora la oportunidad que para lograr esto ofrece la fenomenología como perspectiva teórico-metodológica, y su pertinencia para rescatar el papel protagónico de los actores y su acción, así como la posibilidad de lograr un acercamiento comprensivo a lo que cotidianamente se vive. Al mismo tiempo, busca rescatar la dimensión subjetiva e intersubjetiva propia de las relaciones entre personas que, desde referentes de vida diversos, hacen aparecer a la acción social como parte de un fenómeno complejo.Este artículo presenta algunas reflexiones sobre la importancia de dar un lugar preeminente a los actores, cuando de lo que se trata es de investigar la cotidianidad social. Se valora la oportunidad que para lograr esto ofrece la fenomenología como perspectiva teórico-metodológica, y su pertinencia para rescatar el papel protagónico de los actores y su acción, así como la posibilidad de lograr un acercamiento comprensivo a lo que cotidianamente se vive. Al mismo tiempo, busca rescatar la dimensión subjetiva e intersubjetiva propia de las relaciones entre personas que, desde referentes de vida diversos, hacen aparecer a la acción social como parte de un fenómeno complejo

Irreversibility in quantum maps with decoherence

The Bolztmann echo (BE) is a measure of irreversibility and sensitivity to perturbations for non-isolated systems. Recently, different regimes of this quantity were described for chaotic systems. There is a perturbative regime where the BE decays with a rate given by the sum of a term depending on the accuracy with which the system is time-reversed and a term depending on the coupling between the system and the environment. In addition, a parameter independent regime, characterised by the classical Lyapunov exponent, is expected. In this paper we study the behaviour of the BE in hyperbolic maps that are in contact with different environments. We analyse the emergence of the different regimes and show that the behaviour of the decay rate of the BE is strongly dependent on the type of environment.Comment: 13 pages, 3 figures

Quantitative patterns in drone wars

Attacks by drones (i.e., unmanned combat air vehicles) continue to generate heated political and ethical debates. Here we examine the quantitative nature of drone attacks, focusing on how their intensity and frequency compare with that of other forms of human conflict. Instead of the power-law distribution found recently for insurgent and terrorist attacks, the severity of attacks is more akin to lognormal and exponential distributions, suggesting that the dynamics underlying drone attacks lie beyond these other forms of human conflict. We find that the pattern in the timing of attacks is consistent with one side having almost complete control, an important if expected result. We show that these novel features can be reproduced and understood using a generative mathematical model in which resource allocation to the dominant side is regulated through a feedback loop.Comment: 5 pages, 3 figure

Gene expression noise in stress response as a survival strategy in fluctuating environments

Populations of cells live in uncertain environments, where they encounter large variations in nutrients, oxygen and toxic compounds. In the fluctuating environment, cells can sense their surroundings and express proteins to protect themselves against harmful substances. However, if the stressor appears infrequently or abruptly, sensing can be too costly or too slow, and cells cannot rely solely on it. To hedge against the sudden appearance of a stressor, cell populations can also rely on phenotypic diversification through bet-hedging. In bet-hedging, cells exploit noise in gene expression or use multistable genetic networks to produce an heterogeneous distribution of resistance-conferring protein levels. In this thesis, we analyze novel roles of noise in biological systems. Through a combination of modeling and stochastic simulations, we find that noise can coordinate multi-component stress response mechanisms in a subset of the population with no extra cost. In addition, we use evolutionary algorithms to analyze the conditions where the benefits provided by noise in gene expression are equivalent to those of a more complicated, bistable distribution of protein levels. Our results show that for cells living in noisy fluctuating environments, both noise in gene expression and bistability show similar growth rates, meaning that noise in gene expression can be an effective bet-hedging strategy

Study of P(VDF-TrFE) for Structures via 3D Printing

This work is focussed on using additive manufacturing (AM) to produce electroactive structures using fused deposition modelling (FDM) and P(VDF-TrFE) as a ferroelectric polymer which will confer electroactive properties to printed structures. The FDM, commonly called 3D printing, was chosen due to its emergence in the industry segment with low-cost production and the capability of projecting prototypes without shape limitations, converting a digital design in a physical object. Beyond these features, the possibility of using functional materials and their properties in the production of sensors and actuators was one of the main reasons for the increased interest in this technology. The boundaries of 3D printing process were explored during the production in order to obtain a uniform and homogenous thin film. It was used a P(VDF-TrFE) filament that was previously extruded to make possible the use of additive manufacturing process. Subsequently, a commercial conductive PLA filament was used to produce electrodes for the electrical characterization of the electroactive films. P(VDF-TrFE) films with 65 μm and aluminium electrodes yielded the best results with a pyroelectric coefficient of 3 μC m-2 K-1. The aforementioned sample was used to produce a fully 3D printable pyroelectric sensor. This sensor was made of P(VDF-TrFE), commercial conductive PLA and conventional PLA. The P(VDF-TrFE) provides electroactive properties, conductive PLA enables the creation of conductive tracks and the conventional PLA gave structural basis to the device

Global effects of climate change on animal population dynamics

Climate change affects many statistical descriptions of the environment. The impact of changes in mean environmental conditions on animal populations has been widely reported. The variability and autocorrelation of environmental variables are also changing over time, yet less research has focussed on what impact these changes may have on populations. Is the research focus on changes in mean conditions justified? How do changes in different statistical descriptions of climate change affect populations, and how do the impacts compare? To answer these questions, we developed a simple stochastic population model, explicitly linked to the environment, and compared the impacts of changes in environmental mean and variability. We found, using both the long-term stochastic growth rate and extinction risk as proxies for population fitness, that changes in variability have a significant impact on population dynamics. The main gradient along which the relative importance of changes in environmental mean and variability varied was the population's distance from its ideal environment. We also re-analysed existing population models to yield the sensitivity of the population to changes in environmental mean and variability. Results support the findings from our model, and confirm the importance of changes in variability for population dynamics. Previous theoretical and laboratory studies concluded that the autocorrelation in the environment in part affects the autocorrelation in population time series. So far, this hypothesis has not been tested using empirical data. We used a database of population time series to find that the autocorrelation in mean summer temperature is significantly correlated with the autocorrelation in population time series. Results also show that environmental variables have become less autocorrelated in most geographical regions, suggesting that populations' autocorrelation may also be changing. Autocorrelation in population time series has been linked to extinction; these results may therefore have important implications for animal populations

Structural stability of the two-fold singularity

At a two-fold singularity, the velocity vector of a flow switches discontinuously across a codimension one switching manifold, between two directions that both lie tangent to the manifold. Particularly intricate dynamics arises when the local flow curves toward the switching manifold from both sides, a case referred to as the Teixeira singularity. The flow locally performs two different actions: it winds around the singularity by crossing repeatedly through, and passes through the singularity by sliding along, the switching manifold. The case when the number of rotations around the singularity is infinite has been analyzed in detail. Here we study the case when the flow makes a finite, but previously unknown, number of rotations around the singularity between incidents of sliding. We show that the solution is remarkably simple: the maximum and minimum numbers of rotations made anywhere in the flow differ only by one and increase incrementally with a single parameter -the angular jump in the flow direction across the switching manifold at the singularity

Ineffective Controls on Capital Inflows Under Sophisticated Financial Markets: Brazil in the Nineties

We analyze the Brazilian experience in the 1990s to assess the effectiveness of controls on capital inflows in restricting financial inflows and changing their composition towards long term flows. Econometric exercises (VARs) showed that controls on capital inflows were effective in deterring financial inflows for only a brief period, from two to six months. The hypothesis to explain the ineffectiveness of the controls is that financial institutions performed several operations aimed at avoiding capital controls. To check this hypothesis, we conducted interviews with market players. We collected several examples of the financial strategies engineered to avoid the capital controls and invest in the Brazilian fixed income market. The main conclusion is that controls on capital inflows, while they may be desirable, are of very limited effectiveness under sophisticated financial markets.