Using food-web theory to conserve ecosystems

© 2016, Nature Publishing Group. All rights reserved.Food-web theory can be a powerful guide to the management of complex ecosystems. However, we show that indices of species importance common in food-web and network theory can be a poor guide to ecosystem management, resulting in significantly more extinctions than necessary. We use Bayesian Networks and Constrained Combinatorial Optimization to find optimal management strategies for a wide range of real and hypothetical food webs. This Artificial Intelligence approach provides the ability to test the performance of any index for prioritizing species management in a network. While no single network theory index provides an appropriate guide to management for all food webs, a modified version of the Google PageRank algorithm reliably minimizes the chance and severity of negative outcomes. Our analysis shows that by prioritizing ecosystem management based on the network-wide impact of species protection rather than species loss, we can substantially improve conservation outcomes

The graceful exit in pre-big bang string cosmology

We re-examine the graceful exit problem in the pre-big bang scenario of string cosmology, by considering the most general time-dependent classical correction to the Lagrangian with up to four derivatives. By including possible forms for quantum loop corrections we examine the allowed region of parameter space for the coupling constants which enable our solutions to link smoothly the two asymptotic low-energy branches of the pre-big bang scenario, and observe that these solutions can satisfy recently proposed entropic bounds on viable singularity free cosmologies.Comment: 14 pages, 6 figures, JHEP class. Added new section on the classical correction and reference

The Symbolic Dynamics Of Multidimensional Tiling Systems

We prove a multidimensional version of the theorem that every shift of finite type has a power that can be realized as the same power of a tiling system. We also show that the set of entropies of tiling systems equals the set of entropies of shifts of finite type

Psychologists\u27 Skepticism and Knowledge about Dissociative Identity Disorders in Adolescents

Professional skepticism about DID and lack of knowledge about DID has been documented in the adult literature on dissociative pathology (Hayes and Mitchell, 1994). Although 100% of adult DID cases are thought to have originated in childhood as sequelae of trauma, to date no studies about professional skepticism of and knowledge about DID have been done with psychologists who specialize in assessing children and adolescents. This study was designed to investigate the beliefs about DID and knowledge of DID that has been garnered by psychologists who specialize in assessing and treating adolescents. This study consisted of a convenience sample of 34 participants recruited from the American Psychological Association\u27s Division 53 and from participants surveyed via the Internet. This research replicates the study done by Hayes and Mitchell (1994) utilizing the Skepticism and Knowledge Scale designed by them. The abysmal response rate of 2.7% allowed for descriptive analysis but reduced power in calculating correlations between variables. Results indicated an inverse correlation between the Skepticism and the Knowledge variables. Unlike similar studies in the adult literature about dissociative pathology, participants lacked skepticism about DID and were knowledgeable about DID. Yet only 17.6% of the sample accurately diagnosed the DID vignette. The findings of this study reinforce other research findings (Putnam, 1991) that DID, the paradigmatic Dissociative Disorder, is seldom diagnosed in childhood and adolescence. The limitations of this study suggest that findings should be regarded as exploratory rather than conclusive as those who chose not to participate may have done so because of extreme skepticism as well as lack of knowledge about DID

Sonic boom simulation by means of low-pressure sources

Sonic boom simulation by low pressure source

Comment on "A centroid molecular dynamics study of liquid para hydrogen and ortho deuterium" [J. Chem. Phys. 121, 6412 (2004)]

We show that the two phase points considered in the recent simulations of liquid para hydrogen by Hone and Voth lie in the liquid-vapor coexistence region of a purely classical molecular dynamics simulation. By contrast, their phase point for ortho deuterium was in the one-phase liquid region for both classical and quantum simulations. These observations are used to account for their report that quantum mechanical effects enhance the diffusion in liquid para hydrogen and decrease it in ortho deuterium