Hairy Black Holes in Massive Gravity: Thermodynamics and Phase Structure

The thermodynamic properties of a static and spherically symmetric hairy black hole solution arising in massive gravity with spontaneous Lorentz breaking are investigated. The analysis is carried out by enclosing the black hole in a spherical cavity whose surface is maintained at a fixed temperature $T$. It turns out that the ensemble is well-defined only if the "hair" parameter $Q$ characterizing the solution is conserved. Under this condition we compute some relevant thermodynamic quantities, such as the thermal energy and entropy, and we study the stability and phase structure of the ensemble. In particular, for negative values of the hair parameter, the phase structure is isomorphic to the one of Reissner-Nordstrom black holes in the canonical ensemble. Moreover, the phase-diagram in the plan ($Q,T$) has a line of first-order phase transition that at a critical value of $Q$ terminates in a second-order phase transition. Below this line the dominant phase consists of small, cold black holes that are long-lived and may thus contribute much more to the energy density of the Universe than what is observationally allowed for radiating black holes.Comment: 12 pages, 11 figures, relevant references added, match the published versio

Adiabatic contraction revisited: implications for primordial black holes

We simulate the adiabatic contraction of a dark matter (DM) distribution during the process of the star formation, paying particular attention to the phase space distribution of the DM particles after the contraction. Assuming the initial uniform density and Maxwellian distribution of DM velocities, we find that the number $n(r)$ of DM particles within the radius $r$ scales like $n(r) \propto r^{1.5}$, leading to the DM density profile $\rho\propto r^{-1.5}$, in agreement with the Liouville theorem and previous numerical studies. At the same time, the number of DM particles $\nu(r)$ with periastra smaller than $r$ is parametrically larger, $\nu(r) \propto r$, implying that many particles contributing at any given moment into the density $\rho(r)$ at small $r$ have very elongated orbits and spend most of their time at distances larger than $r$. This has implications for the capture of DM by stars in the process of their formation. As a concrete example we consider the case of primordial black holes (PBH). We show that accounting for very eccentric orbits boosts the amount of captured PBH by a factor of up to $2\times 10^3$ depending on the PBH mass, improving correspondingly the previously derived constraints on the PBH abundance.Comment: 8 pages, 3 figures, discussions added to the "Simulation of DM orbits" part, fig.3 with several DM densities. Revised version to match published versio

The Importance of Food Perception in Food Choices and Nutrition

Nowadays, there is a growing interest in understanding and modulating consumer choices, both for healthy and economic reasons. However, food preferences are influenced by a diversity of factors, which interact among them to a final behaviour. The understanding of food choices is linked with the comprehension of how consumers perceive food and how the different levels of perception (sensorial, psychological, socio-economic) affect those choices. Traditionally, the effect of each discipline was studied independently. Nowadays, the complexity inherent to the decision process is recognized and multidisciplinary studies, where the different dimensions of choices are considered, are increasing. Motivation for consumption is greatly affected by the way individuals identify food. This recognition should be considered at different levels: sensorial, emotional, social and physiological. As such, variability in food characteristics, including food constituents and technological processing, as well as variations in individuals’ characteristics, such as believes, experiences and physiology, and variations in the context in which food is experienced, can greatly affect the final perception.FC

Constraints on primordial black holes as dark matter candidates from capture by neutron stars

We investigate constraints on primordial black holes (PBHs) as dark matter candidates that arise from their capture by neutron stars (NSs). If a PBH is captured by a NS, the star is accreted onto the PBH and gets destroyed in a very short time. Thus, mere observations of NSs put limits on the abundance of PBHs. High DM densities and low velocities are required to constrain the fraction of PBHs in DM. Such conditions may be realized in the cores of globular clusters if the latter are of a primordial origin. Assuming that cores of globular clusters possess the DM densities exceeding several hundred GeV/cm$^3$ would imply that PBHs are excluded as comprising all of the dark matter in the mass range $3\times 10^{18} \text{g} \lesssim m_\text{BH}\lesssim 10^{24} \text{g}$. At the DM density of $2\times 10^3$ GeV/cm$^3$ that has been found in simulations in the corresponding models, less than 5% of the DM may consist of PBH for these PBH masses.Comment: 7 pages, 2 figures, precise computation of dynamical friction added, accepted for publication in PR

Proa à Deriva

Revista Landa, v. 1, n. 1 (2012

The Influence of oral environment on diet choices in goats: a focus on saliva protein composition

There is ample evidence that ruminants are capable of making choices between different foods that provide a more balanced diet that would be obtained by eating at random. In the particular case of goats, they occupy a diversity of habitats and different breeds present variability of feeding behaviors resultant from adaptations to the existent plant species. In their food search activity, individuals are faced with variable amounts of plant secondary metabolites (PSMs), which may present some toxic and anti-nutritional effects depending on the individual’s ability to deal with it. The oral cavity has a key role in the recognition and decision processes of ingestion or rejection. In this chapter we will first consider how goats identify foods and behave according to the food items available. Focus will be done on the importance of taste sense in this process and the information available on the main structures involved in taste detection and perception in goats will be reviewed. In a second section we will focus on the characteristics of goat’s saliva, particularly in terms of their protein composition, presenting results obtained by our research team

`When I'm sixty-four': old age, family values, and private financial transfers

Private financial transfers are becoming more and more important as ageing levels increase in Europe, with elders acting as both givers and receivers. Our study is divided in two main parts. In the first part we analyse the determinants of private financial transfers, using the Survey of Health, Ageing, and Retirement in Europe (SHARE). In the second part we analyse the importance of family values for these transfers, combining SHARE with European Values Study. We show that family functions as the main agent of private transfers. We conclude that family values drive financial transfers, mainly gifts provided by elderly individuals. We find that receipts by old-aged people are more related with need cases, such as illness and poorness; moreover, for these particular cases, family network plays a very important role, working as a safety net

Hérnia inguinal no primeiro ano de vida.

Trabalho de Conclusão de Curso - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Departamento de Pediatria, Curso de Medicina, Florianópolis, 198

Changing climate, changing decisions : understanding climate adaptation decision-making and the way science supports it

Tese de doutoramento, Ciências do Ambiente, Universidade de Lisboa, Faculdade de Ciências, Universidade Nova de Lisboa, 2015The current pace of global mitigation efforts brings about growing concerns about climate change impacts. In turn, even in developed countries, most societies are often vulnerable to present day climate and will most likely see those vulnerabilities exacerbated by future climate trends and extremes, accentuating the need for a coherent response through adaptation efforts. Such efforts will always have to be developed in face of uncertainty. The deeply rooted uncertainties that underpin climate change adaptation as a scientific, political and societal endeavour will always be a part of adaptation decision-making processes. It is fundamental that decision-makers and scientific communities find common ground that allows to exchange the necessary knowledge on “why to adapt”, but also to develop the required frameworks, methods and tools that sustain a clearer understanding of “what to adapt” and “how to adapt” under long-term, uncertain circumstances. This thesis is about climate adaptation decisions and decision-making processes, and how science supports and equips them to handle uncertainty. The assessment and conclusions presented in this thesis reflect research that was transdisciplinary in nature and that included working close to decision-makers in their real-life contexts. The main objective of this thesis is to enrich the understanding of how adaptation decision-making takes place in those contexts and how science can better support it in dealing with associated uncertainties. Three key research questions underpin this thesis. The first deals with the issue whether transdisciplinarity in adaptation research is a fundamental condition for practical adaptation decision-making. This thesis argues that although transdisciplinarity may be a necessary condition, it is not a sufficient one to assure that “good” or “better” real-life adaptation decisions are made. Participatory, practice-oriented research is of outmost importance, but it has to be complemented by a more fundamental inquiry and concept development from disciplinary sciences and with changes in the operational and/or normative standards associated with long-lasting decisions. Transdisciplinarity has been framed as a potential solution for the gap between knowledge production and practical adaptation action. However, a more fundamental change in the way adaptation decision-making processes are framed, one that goes beyond the simple assimilation of the perceived needs of decision-makers, may be required to bridge that challenge. The second question reflects the current gap in the understanding of what climate adaptation decisions are and how they relate to existing or perceived uncertainties. Using a set of selected case-studies spanning across a wide range of sectors and different real-life decisions, this thesis reviewed and analysed how adaptation decisions are being made in practice, their knowledge requirements, and the implications that dealing with uncertainty has regarding their outcomes. In order to consider all steps of the adaptation decision-making process, interviews were conducted with both decision-makers and those involved in supporting them via science and other activities. Results demonstrate the importance of considering both dimensions and respective contexts in dealing with uncertainty. However, results also suggest that uncertainty-management is not a guarantee of action, and that the current framing of adaptation decision-making is still very much tied to a rational-linear view, both from the policy and decision-making perspective, as in the science and decision-support standpoint. This leads to a third research question that aims to identify if current adaptation decision-making frameworks are well equipped to characterise, support adaptation and enhance adaptation action under uncertainty. In the context of this thesis, a decision-making framework is a holistic set of concepts, perspectives or approaches that support the entire adaptation decisionmaking process. This thesis argues that such frameworks should necessarily include and integrate all dimensions that naturally occur in an adaptation process namely, the decision-objectives, the decision-support, the decision-making and the respective decision-outcomes. Current frameworks have been mostly framed from a research and expert perspective that follows a rational approach to decision-making under uncertainty. Under such perspective, it is assumed that by providing information and decision-support practical adaptation decisions will be made. This appears to be sufficient to deal with strategic decisions that look into improving adaptive capacity, but seems no longer fit-for-purpose when it comes to operational decisions, the type generally required to advance vulnerability-reducing actions.Centre for Ecology, Evolution and Environmental Changes (cE3c, project Climate Change Impacts, Adaptation and Modelling - CCIAM); Wageningen University and Research Centr