A Reason for Unreason: Returns-Based Beliefs in Game Theory

Players cooperate in experiments more than game theory would predict. We introduce the ‘returns-based beliefs’ approach: the expected returns of a particular strategy in proportion to total expected returns of all strategies. Using a decision analytic solution concept, Luce’s (1959) probabilistic choice model, and ‘hyperpriors’ for ambiguity in players’ cooperability, our approach explains empirical observations in various classes of games including the Prisoner’s and Traveler’s Dilemmas. Testing the closeness of fit of our model on Selten and Chmura (2008) data for completely mixed 2 × 2 games shows that with loss aversion, returns-based beliefs explain the data better than other equilibrium concepts

Non-Linear Effects in Non-Kerr spacetimes

There is a chance that the spacetime around massive compact objects which are expected to be black holes is not described by the Kerr metric, but by a metric which can be considered as a perturbation of the Kerr metric. These non-Kerr spacetimes are also known as bumpy black hole spacetimes. We expect that, if some kind of a bumpy black hole exists, the spacetime around it should possess some features which will make the divergence from a Kerr spacetime detectable. One of the differences is that these non-Kerr spacetimes do not posses all the symmetries needed to make them integrable. We discuss how we can take advantage of this fact by examining EMRIs into the Manko-Novikov spacetime.Comment: 8 pages, 3 Figures; to appear in the proceedings of the conference "Relativity and Gravitation: 100 Years after Einstein in Prague" (2012

Astrometric effects of gravitational wave backgrounds with non-Einsteinian polarizations

The Gaia mission offers a new opportunity to search for the low-frequency gravitational wave background using astrometric measurements. In this paper, the astrometric effect of gravitational waves is reviewed, with a particular focus on the effect of non-Einsteinian gravitational wave polarizations. A stochastic gravitational wave background generates a correlated vector field of astrometric deflections on the sky. A convenient decomposition for the correlation matrix is introduced, enabling it to be calculated for all possible gravitational wave polarizations and compared to the redshift correlations from the pulsar-timing literature; in the case of a general relativity background of transverse traceless gravitational waves, this also allows us to identify an astrometric analog of the famous Hellings-Downs curve. Finally, the cross correlation between the redshift and astrometric signal is also calculated; this may form the basis for future joint pulsar-timing and astrometry searches for arbitrarily polarized gravitational wave backgrounds.D. M. is funded by the STFC. C. M. acknowledges financial support provided under the European Union’s H2020 ERC Consolidator Grant “Matter and strong-field gravity: New frontiers in Einsteins theory” grant agreement no. MaGRaTh646597. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 690904 and C. M. would like to acknowledge networking support by the COST Action CA16104

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

On the Biological Foundations of Language: Recent Advances in Language Acquisition, Deterioration, and Neuroscience Begin to Converge

In this paper, experimental results on the study of language loss in pro- dromal Alzheimer’s disease (AD) in the elderly are linked to experimen- tal results from the study of language acquisition in the child, via a tran- sitional stage of Mild Cognitive Impairment (MCI). Recent brain imag- ing results from a pilot study comparing prodromal AD and normal ag- ing are reported. Both, behavioral results and their underlying neural underpinnings, identify the source of language deficits in MCI as break- down in syntax–semantics integration. These results are linked to inde- pendent discoveries regarding the ontogeny of language in the child and their neural foundations. It is suggested that these convergent results ad- vance our understanding of the true nature of maturational processes in language, allowing us to reconsider a “regression hypothesis” (e.g., Ribot 1881), wherein later acquisition predicts earliest dissolution

Quantifying fish production by threatened habitats

This is the final version of the article. It was first available from Wiley via http://dx.doi.org/10.1111/1365-2664.125761. Quantification of ecosystem services is increasingly valuable for conservation and restoration decision making. Structured habitats serve as nursery grounds by enhancing juvenile fish and mobile crustacean survival and abundance. This service is challenging to quantify due to ontogenetic shifts in habitat use by many species. 2. We reviewed available literature on the increased abundance of juvenile fish and mobile crustaceans in a key nursery habitat – Crassostrea virginica reefs in the USA. We modelled the growth and mortality of the enhanced species using three different natural mortality (M) estimates to provide estimates of the gross and net lifetime production and uncertainty that can be attributed to the habitat. 3. Recruitment of nineteen and twelve species were found to be enhanced by the addition of C. virginica reefs to previously unstructured habitat in the Gulf of Mexico and the South and Mid Atlantic USA, respectively. This increased recruitment is estimated to result in a mean lifetime enhancement in production of 397 ± 115 (1 SD) g m-2 y-1 in the Gulf of Mexico and 281 ± 56 g m-2 y-1 in the South and Mid Atlantic. 4. The two regions differed with regards to the identity of the enhanced species and their degree of augmentation. Thus, our results highlight the inadequacy of applying regional estimates of ecosystem services to global scales. Furthermore, estimates of total enhancement varied by up to a factor of 2.8 across the three methods of M estimation. 5. Our estimates are quantitative predictions of the ecological benefits derived from the restoration or conservation of a threatened habitat, and advance the field of restoration science beyond qualitative statements that just predict direction of benefit (e.g. increased or decreased). Quantification of the uncertainty in the production estimates further increases their utility for decision makers. 6. Synthesis and applications. Our results can be applied to the restoration or conservation of nursery habitats where habitat is limiting the recruitment of fish species. Quantitative estimates of fisheries productivity enhancement by habitats can be used by managers to determine the expected return on investment in restoration activities, provide testable predictions for monitoring programs, and communicate the value of restoring or conserving habitat.This work was supported by the National Fish and Wildlife Foundation (award no. 2009-0078-000) and by the National Partnership between The Nature Conservancy and NOAA’s Community-based Restoration Programme (award nos. NA07NMF4630136 and NA10NMF463008). Additional funding for the project was provided by the TNC-Shell Partnership and The Turner Foundation, Inc. and the National Science Foundation (OCE-1203859). The authors thank S. Bosarge for constructing the map of study locations and two knowledgeable reviewers for greatly improving this work

On the Biological Foundations of Language: Recent Advances in Language Acquisition, Deterioration, and Neuroscience Begin to Converge

In this paper, experimental results on the study of language loss in pro- dromal Alzheimer’s disease (AD) in the elderly are linked to experimen- tal results from the study of language acquisition in the child, via a tran- sitional stage of Mild Cognitive Impairment (MCI). Recent brain imag- ing results from a pilot study comparing prodromal AD and normal ag- ing are reported. Both, behavioral results and their underlying neural underpinnings, identify the source of language deficits in MCI as break- down in syntax–semantics integration. These results are linked to inde- pendent discoveries regarding the ontogeny of language in the child and their neural foundations. It is suggested that these convergent results ad- vance our understanding of the true nature of maturational processes in language, allowing us to reconsider a “regression hypothesis” (e.g., Ribot 1881), wherein later acquisition predicts earliest dissolution

Physics, Astrophysics and Cosmology with Gravitational Waves

Gravitational wave detectors are already operating at interesting sensitivity levels, and they have an upgrade path that should result in secure detections by 2014. We review the physics of gravitational waves, how they interact with detectors (bars and interferometers), and how these detectors operate. We study the most likely sources of gravitational waves and review the data analysis methods that are used to extract their signals from detector noise. Then we consider the consequences of gravitational wave detections and observations for physics, astrophysics, and cosmology.Comment: 137 pages, 16 figures, Published version <http://www.livingreviews.org/lrr-2009-2

Gravitational Waves From Known Pulsars: Results From The Initial Detector Era

We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of Niedersachsen/GermanyAustralian Research CouncilInternational Science Linkages program of the Commonwealth of AustraliaCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Economia y CompetitividadConselleria d'Economia Hisenda i Innovacio of the Govern de les Illes BalearsNetherlands Organisation for Scientific ResearchPolish Ministry of Science and Higher EducationFOCUS Programme of Foundation for Polish ScienceRoyal SocietyScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space AdministrationOTKA of HungaryLyon Institute of Origins (LIO)National Research Foundation of KoreaIndustry CanadaProvince of Ontario through the Ministry of Economic Development and InnovationNational Science and Engineering Research Council CanadaCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan FoundationAstronom

Self-force: Computational Strategies

Building on substantial foundational progress in understanding the effect of a small body's self-field on its own motion, the past 15 years has seen the emergence of several strategies for explicitly computing self-field corrections to the equations of motion of a small, point-like charge. These approaches broadly fall into three categories: (i) mode-sum regularization, (ii) effective source approaches and (iii) worldline convolution methods. This paper reviews the various approaches and gives details of how each one is implemented in practice, highlighting some of the key features in each case.Comment: Synchronized with final published version. Review to appear in "Equations of Motion in Relativistic Gravity", published as part of the Springer "Fundamental Theories of Physics" series. D. Puetzfeld et al. (eds.), Equations of Motion in Relativistic Gravity, Fundamental Theories of Physics 179, Springer, 201