Restoration Ecology: Two-Sex Dynamics and Cost Minimization

We model a spatially detailed, two-sex population dynamics, to study the cost of ecological restoration. We assume that cost is proportional to the number of individuals introduced into a large habitat. We treat dispersal as homogeneous diffusion. The local population dynamics depends on sex ratio at birth, and allows mortality rates to differ between sexes. Furthermore, local density dependence induces a strong Allee effect, implying that the initial population must be sufficiently large to avert rapid extinction. We address three different initial spatial distributions for the introduced individuals; for each we minimize the associated cost, constrained by the requirement that the species must be restored throughout the habitat. First, we consider spatially inhomogeneous, unstable stationary solutions of the model's equations as plausible candidates for small restoration cost. Second, we use numerical simulations to find the smallest cluster size, enclosing a spatially homogeneous population density, that minimizes the cost of assured restoration. Finally, by employing simulated annealing, we minimize restoration cost among all possible initial spatial distributions of females and males. For biased sex ratios, or for a significant between-sex difference in mortality, we find that sex-specific spatial distributions minimize the cost. But as long as the sex ratio maximizes the local equilibrium density for given mortality rates, a common homogeneous distribution for both sexes that spans a critical distance yields a similarly low cost

Building Damage-Resilient Dominating Sets in Complex Networks against Random and Targeted Attacks

We study the vulnerability of dominating sets against random and targeted node removals in complex networks. While small, cost-efficient dominating sets play a significant role in controllability and observability of these networks, a fixed and intact network structure is always implicitly assumed. We find that cost-efficiency of dominating sets optimized for small size alone comes at a price of being vulnerable to damage; domination in the remaining network can be severely disrupted, even if a small fraction of dominator nodes are lost. We develop two new methods for finding flexible dominating sets, allowing either adjustable overall resilience, or dominating set size, while maximizing the dominated fraction of the remaining network after the attack. We analyze the efficiency of each method on synthetic scale-free networks, as well as real complex networks

ON SOME SYMPLECTIC GROUP ACTIONS WHERE ALL THE ORBITS ARE EQUIVARIANTLY ISOMORPHIC AND DIFFEOMORPHIC TO A FIXED ORBIT OF THE COADJOINT ACTION

In conformity with the 'Foundations of Mechanics' given by R. ABRAHAM and J. E. MARSDEN [1] let (P,w) be a symplectic manifold and Φ:GxP-P a Hamiltonian action of a compact, connected Lie group G on the manifold P. Considering this setting J. SZENTHE [2] found the following result: If the isotropy subgroups of the action Φ are of maximal rank then all the orbits of Φ are equivariantly isomorphic. Consequently, P is the total space of a differentiable fibre bundle, where the base manifold is the orbit space of the action Φ and the fibres are diffeomorphic to a fixed orbit of the coadjoint action. The aim of the present paper is to develop further characterizations of the above situation as it was suggested by J. J. DUISTERMAAT

Playing on the global periphery: Social scientific explorations of rugby in the Pacific Islands

In this prologue, we will briefly revisit some of the main research findings that have emerged from our collaborative work on Fiji rugby, as well as reflecting on some of the recommendations derived from our empirical investigation. We discuss issues in relation to national identity and migrations, post-rugby career-related retirement issues and alternative emerging cultural practices that challenge the dominant discourse around Fiji rugby. We then turn our attention to the content of this special issue and briefly introduce the articles included, with the main recommendation that there is a growing need to explore absent and emerging voices and cultural practices in regard to sport-related migration in, from and to the Pacific Islands

Signs of Thermalization from RHIC Experiments

Selected results from the first five years of RHIC data taking are reviewed with emphasis on evidence for thermalization in central Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.Comment: 10 pages, 6 figure

Searching for Masculine Capital: Experiences Leading to High Drive for Muscularity in Men

Studies on the drive for muscularity (DFM) have primarily been quantitative, focused on identifying correlates. Currently little is known about men’s experiences leading them to desire high levels of muscle and engage in behaviours to increase their masculine capital. Our purpose was to explore the stories of men with high DFM revealing the socio-cultural and personal factors leading to DFM and their search for masculine capital. In-depth life-history interviews and multiple in-the-field conversations were undertaken with twenty men (Mean age=28.45, SD=6.96, years) scoring ≥ 3 on the Drive for Muscularity Scale (Mean=4.30, SD=0.70). Men’s stories focused on a set of dysfunctional childhood and adolescent socio-cultural interactions, including forms of symbolic violence, between them and significant others. In these interactions men were exposed to dominant social narratives of masculinity, and through comparisons and reinforcement they identified discrepancies between themselves and these narratives. In late adolescence and early adulthood men came to believe that they lacked masculine capital. Men struggled to increase their masculine capital through engagement with other traditional masculine activities (e.g., sport) and driven by activating events, they compensated through DFM desires and behaviours. This study advances knowledge by revealing the socio-cultural and personal processes participants believed led to their high DFM. Findings disclose that men’s search for masculine capital may have led them to develop and maintain high levels of DFM