Bayesian Dynamic Tensor Regression

High- and multi-dimensional array data are becoming increasingly available. They admit a natural representation as tensors and call for appropriate statistical tools. We propose a new linear autoregressive tensor process (ART) for tensor-valued data, that encompasses some well-known time series models as special cases. We study its properties and derive the associated impulse response function. We exploit the PARAFAC low-rank decomposition for providing a parsimonious parametrization and develop a Bayesian inference allowing for shrinking effects. We apply the ART model to time series of multilayer networks and study the propagation of shocks across nodes, layers and time

Creative connectivity project – A network based approach to understand correlations between interdisciplinary group dynamics and creative performance

Creativity, technology and innovation are fundamental driving forces that often trigger behavioural and cultural changes in our societies. Several studies on creative collaborations emphasise the interconnection between the creation of innovation and interdisciplinarity. Studying the interdisciplinary processes through which innovation is generated is thus of fundamental importance. The Creative Connectivity project investigates the links between group dynamics and interdisciplinary creative processes in the attempt to identify the emergence of meaningful behavioural patterns. Taking the Innovation Design Engineering (IDE) programme at the Royal College of Art as a case study, the research addresses the need to develop a more rigorous understanding of the creation of innovation fostered by diversity, a risk-taking culture and acceptance of failure. A novel approach combining data science and network theory has been developed to monitor, quantify and analyse specific dynamics of interdisciplinary groups of students at the IDE programme. The focus was to investigate the network contribution to the performance of a team in an environment that is naturally interdisciplinary by using data respectively from a bespoke developed web application and a conversation activity monitoring system. Initial findings have shown the potential of this approach to unveiling the hidden mechanisms behind creativity and the production of innovation through interdisciplinary approaches. The results of this research could be of interest for universities, research centres, start-ups incubators, and policymakers who want to foster creativity and trigger innovative processes

The BMV experiment : a novel apparatus to study the propagation of light in a transverse magnetic field

In this paper, we describe in detail the BMV (Bir\'efringence Magn\'etique du Vide) experiment, a novel apparatus to study the propagation of light in a transverse magnetic field. It is based on a very high finesse Fabry-Perot cavity and on pulsed magnets specially designed for this purpose. We justify our technical choices and we present the current status and perspectives.Comment: To be published in the European Physical Journal

Ultrafast Resonant Polarization Interferometry: Towards the First Direct Detection of Vacuum Polarization

Vacuum polarization, an effect predicted nearly 70 years ago, is still yet to be directly detected despite significant experimental effort. Previous attempts have made use of large liquid-helium cooled electromagnets which inadvertently generate spurious signals that mask the desired signal. We present a novel approach for the ultra-sensitive detection of optical birefringence that can be usefully applied to a laboratory detection of vacuum polarization. The new technique has a predicted birefringence measurement sensitivity of $\Delta n \sim 10^{20}$ in a 1 second measurement. When combined with the extreme polarizing fields achievable in this design we predict that a vacuum polarization signal will be seen in a measurement of just a few days in duration.Comment: 9 pages, 2 figures. submitted to PR

Exploring the seismic expression of fault zones in 3D seismic volumes

Acknowledgments The seismic interpretation and image processing has been run in the SeisLab facilty at the University of Aberdeen (sponsored by BG, BP and Chevron) Seismic imaging analysis was performed in GeoTeric (ffA), and Mathematica (Wolfram research). Interpretation of seismic amplitudes was performed Petrel 2014 (Schlumberger). We thank Gaynor Paton (Geoteric) for in depth discussion on the facies analysis methodology and significant suggestions to improve the current paper. We thank the New Zealand government (Petroleum and Minerals ministry) and CGG for sharing the seismic dataset utilized in this research paper. Seismic images used here are available through the Virtual Seismic Atlas (www.seismicatlas.org). Nestor Cardozo and an anonymous reviewer are thanked for their constructive comments and suggestions that strongly improved the quality and organization of this paper.Peer reviewedPostprin

Limits on the violation of g-universality with a Galileo-type experiment

Abstract We present new results for a Galilean experiment using two masses of copper and tungsten in simultaneous free fall. The experiment searches for a possible difference in the free-fall acceleration Δ g and it is sensitive to any composition-dependent interaction between the test masses and the earth, whose range exceeds 10 km. The results show no evidence for any composition-dependent gravity-like interaction within Δg μ Gal

Tectonic and stratigraphic evolution based on seismic sequence stratigraphy: Central rift section of the campos basin, offshore brazil

The rift section of the Brazilian basins represent the sedimentary record associated with the first stages of Gondwana break‐up in the Early Cretaceous phase (Berriasian to Aptian). The rift succession of the Campos Basin constitutes one of the main petroleum systems of Brazil’s marginal basins. This interval contains the main source rock and important reservoirs in the Lagoa Feia Group deposits. The Lagoa Feia Group is characterized by siliciclastic, carbonate and evaporite sediments deposited during the rift and post‐rift phases. Despite the economic relevance, little is known in stratigraphic terms regarding this rift interval. To date, most studies of the Lagoa Feia Group have adopted a lithostratigraphic approach, while this study proposes a tectonostrati-graphic framework for the deep‐rift succession of the Campos Basin (Lagoa Feia Group), using the fundamentals of seismic sequence stratigraphy. This work also aims to establish a methodological and practical procedure for the stratigraphic analysis of rift basins, using seismic data and seismofacies, and focusing on tectonicstratigraphic analysis. The dataset comprised 2D seismic lines, core and lithological logs from exploration wells. Three seismic facies were identified based on reflector patterns and lithologic data from well cores, providing an improved subdivision of the pre‐, syn‐ and post‐rift stages. The syn‐rift stage was further subdivided based on the geometric patterns of the reflectors. Tectonics was the main controlling factor in the sedimentary succession, and the pattern and geometry of the seismic reflectors of the syn‐rift interval in the Campos Basin allowed the identification of three tectonic systems tracts: (i) a Rift Initiation Systems Tract; (ii) a High Tectonic Activity Systems Tract and (iii) a Low Tectonic Activity Systems Tract

Impact of the East African Rift System on the routing of the deep‐water drainage network offshore Tanzania, western Indian Ocean

Peer reviewedPostprin

Casimir forces and non-Newtonian gravitation

The search for non-relativistic deviations from Newtonian gravitation can lead to new phenomena signalling the unification of gravity with the other fundamental interactions. Various recent theoretical frameworks indicate a possible window for non-Newtonian forces with gravitational coupling strength in the micrometre range. The major expected background in the same range is attributable to the Casimir force or variants of it if dielectric materials, rather than conducting ones, are considered. Here we review the measurements of the Casimir force performed so far in the micrometre range and how they determine constraints on non-Newtonian gravitation, also discussing the dominant sources of false signals. We also propose a geometry-independent parameterization of all data in terms of the measurement of the constant c. Any Casimir force measurement should lead, once all corrections are taken into account, to a determination of the constant c which, in order to assess the accuracy of the measurement, can be compared with its more precise value known through microscopic measurements. Although the last decade of experiments has resulted in solid demonstrations of the Casimir force, the situation is not conclusive with respect to being able to discover new physics. Future experiments and novel phenomenological analysis will be necessary to discover non-Newtonian forces or to push the window for their possible existence into regions of the parameter space which theoretically appear unnatural.Comment: Also available at http://www.iop.org/EJ/abstract/1367-2630/8/10/23