Sanitizing the fortress: protection of ant brood and nest material by worker antibiotics

Social groups are at particular risk for parasite infection, which is heightened in eusocial insects by the low genetic diversity of individuals within a colony. To combat this, adult ants have evolved a suite of defenses to protect each other, including the production of antimicrobial secretions. However, it is the brood in a colony that are most vulnerable to parasites because their individual defenses are limited, and the nest material in which ants live is also likely to be prone to colonization by potential parasites. Here, we investigate in two ant species whether adult workers use their antimicrobial secretions not only to protect each other but also to sanitize the vulnerable brood and nest material. We find that, in both leaf-cutting ants and weaver ants, the survival of the brood was reduced and the sporulation of parasitic fungi from them increased, when the workers nursing them lacked functional antimicrobial-producing glands. This was the case for both larvae that were experimentally treated with a fungal parasite (Metarhizium) and control larvae which developed infections of an opportunistic fungal parasite (Aspergillus). Similarly, fungi were more likely to grow on the nest material of both ant species if the glands of attending workers were blocked. The results show that the defense of brood and sanitization of nest material are important functions of the antimicrobial secretions of adult ants and that ubiquitous, opportunistic fungi may be a more important driver of the evolution of these defenses than rarer, specialist parasites

CNA 8170: linhagem de arroz adaptada para o ecossistema terra firme do Estado do Pará.

Cópia de trabalho editado em CD-ROM

The relationship between board’s diversity and the reputation of integrated reports

The integrated reporting arises as an answer to the insufficiency of traditional financial report and the emergent need to disclose non-financial information to stakeholders, and it is proposed by the International Integrated Reporting Council. Given the influence of corporate governance on corporate disclosure and the key role of the companies’ board of directors in managing the disclosure of a wide range of information, the present study aims to analyze how some corporate governance characteristics may influence the reputation of integrated reports, distinguishing between reference reports and regular reports. The sample of this study comprises 374 reporters extracted from the IIRC Examples Database. The results show that the size and the experience of the board of directors does not influence the reputation of the integrated reports. In turn, the independence of the board and gender diversity influence positively the reputation of integrated reports, while role duality seems to influence negatively.info:eu-repo/semantics/publishedVersio

Hydro-wind balance in daily electricity markets : a case-study

ABSTRACT: The European Union has been one of the major drivers of the development of renewable energy. In Portugal, renewable generation is subject to specific licensing requirements and benefits from a feed-in-tariff. This paper pays special attention to wind and hydroelectric technologies. Typically, wind farms produce more energy during the night (off-peak periods), when the demand is lower, contributing to a reduction of the market price. Hydroelectric power plants use off-peak periods to pump water, and produce energy in the periods of a 24 hour day where the prices of electricity are higher (peak periods). This paper presents a case study aiming at analyzing the behavior of hydroelectric power producers—that is, in power systems with large renewable generation, producers typically use the periods of the day with lower energy prices for pumping, and the other periods (with higher energy prices) to produce electricity. The simulations are performed using MATREM (for Multi-Agent Trading in Electricity Markets). The results confirm (and rebate) the typical behavior of hydroelectric power producers.info:eu-repo/semantics/publishedVersio

Irrigação de hortaliças no Estado do Amapá.

O clima e a demanda de água das hortaliças; Irrigação das hortaliças; Evapotranspiração da cultura; Evapotranspiração de referência; Método de Blaney-Criddle; Método do tanque classe a; Cálculo da evapotranspiração da cultura; Métodos de irrigação; Irrigação por gotejamento; Instalação de irrigação por gotejamento na horta; Irrigação por mangueiras de polietileno de baixa densidade perfuradas a raio laser; Irrigação por aspersão; Controle da irrigação.bitstream/CPAF-AP/8686/1/Circular200433.PD

Partition functions and elliptic genera from supergravity

We develop the spacetime aspects of the computation of partition functions for string/M-theory on AdS(3) xM. Subleading corrections to the semi-classical result are included systematically, laying the groundwork for comparison with CFT partition functions via the AdS(3)/CFT(2) correspondence. This leads to a better understanding of the "Farey tail" expansion of Dijkgraaf et. al. from the point of view of bulk physics. Besides clarifying various issues, we also extend the analysis to the N=2 setting with higher derivative effects included.Comment: 34 page

Thermodynamic Formalism on the Skorokhod space: the continuous time Ruelle operator, entropy, pressure, entropy production and expansiveness

Consider the semi-flow given by the continuous time shift $\Theta_t:\mathcal{D} \to \mathcal{D}$, $t \geq 0$, acting on the Skorokhod space $\mathcal{D}$, of paths $w: [0,\infty) \to S^1$, where $S^1$ is the unitary circle We show that the semi-flow is expanding. We consider a stochastic semi-group $e^{t\, L}$, $t \geq 0,$ where $L$ (the infinitesimal generator) This stochastic semi-group and an initial vector of probability $\pi$ defines an associated stationary shift-invariant probability $\mathbb{P}$. This probability $\mathbb{P}$ will play the role of an {\it a priori} probability. Given such $\mathbb{P}$ and a H\"older potential $V:S^1 \to \mathbb{R}$, we define a continuous time Ruelle operator: a family of linear operators $\mathbb{L}^t_V$, $t\geq 0,$ acting on continuous functions $\varphi: S^1 \to \mathbb{R}$, defined by $\varphi \,\to \psi(y) = \mathbb{L}^t_V(\varphi)(y)= \int_{w(t)=y} e^{ \int_0^t V(w(s)) \, ds} \, \varphi (w(0)) \,d \mathbb{P}(w).\,$ We show the existence of an eigenvalue $\lambda_V$ and an associated H\"older eigenfunction $\varphi_V>0$ for the semi-group $\mathbb{L}_V^t$, $t\geq 0.$ After a coboundary procedure we obtain another stochastic semi-group, with infinitesimal generator $L_V$, and this will define a new probability $\mathbb{P}_V$ on $\mathcal{D}$, which we call the Gibbs (or, equilibrium) probability for the potential $V$. We define entropy, for some shift-invariant probabilities on $\mathcal{D}$, and we consider a variational problem of pressure. Finally, we define entropy production and we analyze its relation with time-reversal and symmetry of $L$. We wonder if the point of view described here provides a sketch (as an alternative for the Anosov one) for the chaotic hypothesis for a particle system held in a nonequilibrium stationary state, as delineated by Ruelle, Gallavotti, and Cohen