Physics of Neutron Star Crusts

The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.Comment: 182 pages, published version available at <http://www.livingreviews.org/lrr-2008-10

f(R) theories

Over the past decade, f(R) theories have been extensively studied as one of the simplest modifications to General Relativity. In this article we review various applications of f(R) theories to cosmology and gravity - such as inflation, dark energy, local gravity constraints, cosmological perturbations, and spherically symmetric solutions in weak and strong gravitational backgrounds. We present a number of ways to distinguish those theories from General Relativity observationally and experimentally. We also discuss the extension to other modified gravity theories such as Brans-Dicke theory and Gauss-Bonnet gravity, and address models that can satisfy both cosmological and local gravity constraints.Comment: 156 pages, 14 figures, Invited review article in Living Reviews in Relativity, Published version, Comments are welcom

Ultrasonic intensification as a tool for enhanced microbial biofuel yields

peer-reviewedUltrasonication has recently received attention as a novel bioprocessing tool for process intensification in many areas of downstream processing. Ultrasonic intensification (periodic ultrasonic treatment during the fermentation process) can result in a more effective homogenization of biomass and faster energy and mass transfer to biomass over short time periods which can result in enhanced microbial growth. Ultrasonic intensification can allow the rapid selective extraction of specific biomass components and can enhance product yields which can be of economic benefit. This review focuses on the role of ultrasonication in the extraction and yield enhancement of compounds from various microbial sources, specifically algal and cyanobacterial biomass with a focus on the production of biofuels. The operating principles associated with the process of ultrasonication and the influence of various operating conditions including ultrasonic frequency, power intensity, ultrasonic duration, reactor designs and kinetics applied for ultrasonic intensification are also described

Molecular and Functional Ecology of Sponges and Their Microbial Symbionts

Sponge-microbe symbiotic interactions are important features of modern marine ecosystems. It is likely that these ancient partnerships are as old as the phylum Porifera. Powerful new tools have exposed remarkable microbial diversity within sponge tissues. We are now able to study the composition and structure of the microbial communities at unprecedented levels of resolution. We also recognize that the partnership cannot be disaggregated and should be considered as an integrated holobiont. New hypotheses (e.g., the sponge loop hypothesis) have opened exciting avenues for future experimental work that link holobiont performance from micro- to macro-perspectives. This type of research has taken on added significance given that our planet is experiencing accelerating rates of ocean warming and ocean acidification. It is essential that we examine how sponges respond to environmental stressors that are increasing in intensity and frequency. This review focuses on the molecular and functional ecology of sponge-based microbial symbioses. We discuss the coevolutionary processes that operate to generate partner specificity or to maintain promiscuous partnerships and consider reciprocal selective forces that shape the material exchanges that occur between the partners. We focus attention on the functional ecological role the holobiont plays in marine habitats. The role that the symbionts play in host physiology, and ultimately in the function of sponges on marine ecosystems, is also discussed. We stand to gain important basic information about symbiotic interactions through the detailed study of sponge-microbe interactions, but important practical lessons will be afforded to resource managers who are looking for strategies to protect aquatic habitats worldwide.Peer reviewe