Towards a framework for testing general relativity with extreme-mass-ratio-inspiral observations

Extreme-mass-ratio-inspiral observations from future space-based gravitational-wave detectors such as LISA will enable strong-field tests of general relativity with unprecedented precision, but at prohibitive computational cost if existing statistical techniques are used. In one such test that is currently employed for LIGO black hole binary mergers, generic deviations from relativity are represented by N deformation parameters in a generalized waveform model; the Bayesian evidence for each of its 2N combinatorial submodels is then combined into a posterior odds ratio for modified gravity over relativity in a null-hypothesis test. We adapt and apply this test to a generalized model for extreme-mass-ratio inspirals constructed on deformed black hole spacetimes, and focus our investigation on how computational efficiency can be increased through an evidence-free method of model selection. This method is akin to the algorithm known as product-space Markov chain Monte Carlo, but uses nested sampling and improved error estimates from a rethreading technique. We perform benchmarking and robustness checks for the method, and find order-of-magnitude computational gains over regular nested sampling in the case of synthetic data generated from the null model.AJKC acknowledges support from the Jet Propulsion Laboratory (JPL) Research and Technology Development programme. SH thanks the Science and Technology Facilities Council (STFC) for financial support. CJM acknowledges financial support provided under the European Union’s H2020 ERC Consolidator Grant ‘Matter and strong-field gravity: New frontiers in Einstein’s theory’ grant agreement no. MaGRaTh646597, and networking support by the COST Action CA16104. Parts of this work were performed using the Darwin Supercomputer of the University of Cambridge High Performance Computing Service (http://www.hpc.cam.ac.uk/), provided by Dell Inc. using Strategic Research Infrastructure Funding from the Higher Education Funding Council for England and funding from STFC. Parts of this work were also undertaken on the COSMOS Shared Memory system at DAMTP, University of Cambridge operated on behalf of the STFC DiRAC HPC Facility; this equipment is funded by BIS National E-infrastructure capital grant ST/J005673/1 and STFC grants ST/H008586/1, ST/K00333X/1. Parts of this work were also carried out at JPL, California Institute of Technology, under a contract with the National Aeronautics and Space Administration

The identification of bacteria associated with periodontal disease and dental caries by enzymatic methods

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73856/1/j.1399-302X.1986.tb00322.x.pd

Oxidative stress, lysosomal damage and dysfunctional autophagy in molluscan hepatopancreas (digestive gland) induced by chemical contaminants

Autophagy is a highly conserved evolutionary survival or defence process that enables cells and organisms to survive periods of environmental stress by breaking down cellular organelles and macromolecules in autolysosomes to provide a supply of nutrients for cell maintenance. However, autophagy is also a part of normal cellular physiology that facilitates the turnover of cellular constituents under normal conditions: it can be readily augmented by mild environmental stress; but becomes dysfunctional with severe oxidative stress leading to cellular pathology. The molluscan hepatopancreas or digestive gland provides a versatile and environmentally relevant model to investigate lysosomal autophagy and stress-induced dysfunctional autophagy. This latter process has been implicated in many animal and human disease conditions, including degenerative and neurodegenerative diseases, as well as obesity related conditions. Many environmental pollutants have also been found to induce dysfunctional autophagy in molluscan hepatopancreatic digestive cells, and in this study, the marine blue mussel Mytilus galloprovincialis was exposed for 7 days to: 0.1 μM, 1 μM and 10 μM concentrations of fluoranthene and phenanthrene (PAHs); chlorpyrifos and malathion (organophosphorus compounds); atrazine (triazine herbicide); copper (transition metal) and dodecylbenzene sulphonic acid (LAS, surfactant). The marine snail or periwinkle, Littorina littorea, was also exposed to phenanthrene, chlorpyrifos and copper. Indices of oxidative stress, cell injury and dysfunctional autophagy were measured (i.e., lysosomal membrane stability, protein carbonyls, lipofuscin, and lysosomal accumulation of lipid or lipidosis). Evidence of oxidative stress, based on the elevation of lipofuscin and protein carbonyls, was found for all compounds tested; with chlorpyrifos being the most toxic to both species. Dysfunctional autophagy was induced by all of the compounds tested in both species, except for atrazine in mussels. This failure of normal autophagy was consistently associated with oxidative stress. Autophagic dysfunction is an important emerging feature in the aetiology of many disease conditions in animals and humans; and an explanatory conceptual mechanistic model has been developed for dysregulation of autophagy in response to oxidative stress

Non-Standard Structure Formation Scenarios

Observations on galactic scales seem to be in contradiction with recent high resolution N-body simulations. This so-called cold dark matter (CDM) crisis has been addressed in several ways, ranging from a change in fundamental physics by introducing self-interacting cold dark matter particles to a tuning of complex astrophysical processes such as global and/or local feedback. All these efforts attempt to soften density profiles and reduce the abundance of satellites in simulated galaxy halos. In this contribution we are exploring the differences between a Warm Dark Matter model and a CDM model where the power on a certain scale is reduced by introducing a narrow negative feature (''dip''). This dip is placed in a way so as to mimic the loss of power in the WDM model: both models have the same integrated power out to the scale where the power of the Dip model rises to the level of the unperturbed CDM spectrum again. Using N-body simulations we show that that the new Dip model appears to be a viable alternative to WDM while being based on different physics: where WDM requires the introduction of a new particle species the Dip stems from a non-standard inflationary period. If we are looking for an alternative to the currently challenged standard LCDM structure formation scenario, neither the LWDM nor the new Dip model can be ruled out with respect to the analysis presented in this contribution. They both make very similar predictions and the degeneracy between them can only be broken with observations yet to come.Comment: 4 pages, 3 figures; to appear in "The Evolution of Galaxies III. From Simple Approaches to Self-Consistent Models", proceedings of the 3rd EuroConference on the evolution of galaxies, held in Kiel, Germany, July 16-20, 200

Galaxy Harassment and the Evolution of Clusters of Galaxies

Disturbed spiral galaxies with high rates of star formation pervaded clusters of galaxies just a few billion years ago, but nearby clusters exclude spirals in favor of ellipticals. ``Galaxy harassment" (frequent high speed galaxy encounters) drives the morphological transformation of galaxies in clusters, provides fuel for quasars in subluminous hosts and leaves detectable debris arcs. Simulated images of harassed galaxies are strikingly similar to the distorted spirals in clusters at $z \sim 0.4$ observed by the Hubble Space Telescope.Comment: Submitted to Nature. Latex file, 7 pages, 10 photographs in gif and jpeg format included. 10 compressed postscript figures and text available using anonymous ftp from ftp://ftp-hpcc.astro.washington.edu/pub/hpcc/moore/ (mget *) Also available at http://www-hpcc.astro.washington.edu/papers

<i>Trypanosoma brucei rhodesiense</i> transmitted by a single tsetse fly bite in vervet monkeys as a model of human African trypanosomiasis

Sleeping sickness is caused by a species of trypanosome blood parasite that is transmitted by tsetse flies. To understand better how infection with this parasite leads to disease, we provide here the most detailed description yet of the course of infection and disease onset in vervet monkeys. One infected tsetse fly was allowed to feed on each host individual, and in all cases infections were successful. The characteristics of infection and disease were similar in all hosts, but the rate of progression varied considerably. Parasites were first detected in the blood 4-10 days after infection, showing that migration of parasites from the site of fly bite was very rapid. Anaemia was a key feature of disease, with a reduction in the numbers and average size of red blood cells and associated decline in numbers of platelets and white blood cells. One to six weeks after infection, parasites were observed in the cerebrospinal fluid (CSF), indicating that they had moved from the blood into the brain; this was associated with a white cell infiltration. This study shows that fly-transmitted infection in vervets accurately mimics human disease and provides a robust model to understand better how sleeping sickness develops

Comparative historical sociology and the State : problems of method

Historical sociology can be understood both as a specific sub-field of sociology and as providing general conceptual underpinnings of the discipline, to the extent that it provides an understanding of the specificity of the modern state and the perceived emergence of modernity within Europe. The association of modernity with Europe (and with a European history limited to the self-identified boundaries of the continent) is commonplace and pervasive within the social sciences and humanities. What such an understanding fails to take into consideration, however, are the connections between Europe and the rest of the world that constitute the broader context for the emergence of what is understood to be the modern world and its institutions, such as the state and market. In this article, I suggest that integral to this misunderstanding, and its reproduction over time, is the methodology of comparative historical sociology as represented by ideal types. In contrast, I argue for ‘connected sociologies’ as a more appropriate way to understand our shared past and its continuing impact upon the present. I examine these issues in the context of historical sociological understandings of nation-state formation

Developmental and evolutionary significance of the zygomatic bone

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