1,607 research outputs found
Analysis of NOAA particle data and correlations to seismic activity
Abstract. A decade of NOAA-15 particle flux data offers an opportunity to test claims of correlations between seismic activity and effects on the ionosphere. Over the last two decades, potentially interesting observations in the ionosphere-magnetosphere transition region have been investigated. Specifically these consists of anomalous particle fluxes detected by several space experiments and correlated with the earthquake occurrence. These particle fluxes are characterised by anomalous short-term and sharp increases in high energy particle counting rates, referred to as particle bursts. In this work, more general rules for particle bursts selection have been defined and tested on the NOAA database, for particles inside and outside the South Atlantic Anomaly region. The whole period of ten years burst activity from NOAA-15 database is reported. Data from four satellites, NOAA-15, 16, 17 and 18, were analyzed during periods of solar quiet activity in connection with strong earthquakes, revealing presence of bursts detected on more than one satellite close to the time of the same seismic events. This preliminary study presented here concentrates on periods of major Indonesian earthquakes from 1998 to date, including Sumatra event M=9, during which geomagnetic Ap index was less than 16 and with no sudden ionospheric disturbances. During this period particle burst temporal distributions have shown some correspondence with earthquake times. The limits of the analysis presented in this papers are discussed as well as prospects for future work
Gravitational Waves from Rotating Proto-Neutron Stars
We study the effects of rotation on the quasi normal modes (QNMs) of a newly
born proto neutron star (PNS) at different evolutionary stages, until it
becomes a cold neutron star (NS). We use the
Cowling approximation, neglecting spacetime perturbations, and consider
different models of evolving PNS. The frequencies of the modes of a PNS are
considerably lower than those of a cold NS, and are further lowered by
rotation; consequently, if QNMs were excited in a sufficiently energetic
process, they would radiate waves that could be more easily detectable by
resonant-mass and interferometric detectors than those emitted by a cold NS. We
find that for high rotation rates, some of the g-modes become unstable via the
CFS instability; however, this instability is likely to be suppressed by
competing mechanisms before emitting a significant amount of gravitational
waves.Comment: 5 pages, proceedings of the 5th Edoardo Amaldi Conference On
Gravitational Wave
Vulnerable yet relevant: the two dimensions of climate-related financial disclosure
Market-based solutions to climate change are widely advocated by financial actors
and policy makers in order to foster a smooth transition to a low-carbon economy. A first
important limiting factor to this approach is widely recognized to be the imperfect information
on investors' portfolios' exposure to climate-related risks. While better disclosure of climaterelevant
information is often recommended as a remedy, the current lack of concise and
comparable measures of portfolios' exposure to climate risk fails to provide major investors
with the full incentives to reallocate their portfolios. A second limiting factor arises from the
fact that in the context of the low-carbon transition, it is not clear how to measure the market
share of participants because many economic sectors produce greenhouse gases (GHG)
emissions or induce them along the supply chain. The lack of common and concise measures
of the relevant market share hampers the ability of policy makers to ensure fair competition
policies and the ability of major investors to assess the effects of their own and their
competitors' portfolio reallocation. To address these two gaps, we propose two novel and
complementary indices: (i) the "GHG exposure," capturing the exposure of single investors'
portfolios to climate transition risks, and (ii) "GHG holding," capturing the market share of
each financial actor weighted by its contribution to GHG emissions. We illustrate the use of the
indices on a dataset of portfolios of equity holdings and loans in the Euro-Area, and we discuss
the policy implications for the low-carbon transition
Determination of the forward slope in and elastic scattering up to LHC energy
In the analysis of experimental data on (or ) elastic
differential cross section it is customary to define an average forward slope
in the form , where is the momentum transfer. Taking as
working example the results of experiments at Tevatron and SPS, we will show
with the help of the impact picture approach, that this simplifying assumption
hides interesting information on the complex non-flip scattering amplitude, and
that the slope is not a constant. We investigate the variation of this
slope parameter, including a model-independent way to extract this information
from an accurate measurement of the elastic differential cross section. An
extension of our results to the LHC energy domain is presented in view of
future experiments.Comment: 12 pages, 6 figures, to appear in EPJ
Silicon photomultiplier arrays - a novel photon detector for a high resolution tracker produced at FBK-irst, Italy
A silicon photomultiplier (SiPM) array has been developed at FBK-irst having
32 channels and a dimension of 8.0 x 1.1 mm^2. Each 250 um wide channel is
subdivided into 5 x 22 rectangularly arranged pixels. These sensors are
developed to read out a modular high resolution scintillating fiber tracker.
Key properties like breakdown voltage, gain and photon detection efficiency
(PDE) are found to be homogeneous over all 32 channels of an SiPM array. This
could make scintillating fiber trackers with SiPM array readout a promising
alternative to available tracker technologies, if noise properties and the PDE
are improved
Evolution equations for slowly rotating stars
We present a hyperbolic formulation of the evolution equations describing
non-radial perturbations of slowly rotating relativistic stars in the
Regge--Wheeler gauge. We demonstrate the stability preperties of the new
evolution set of equations and compute the polar w-modes for slowly rotating
stars.Comment: 27 pages, 2 figure
Credit Chains and Bankruptcy Propagation in Production Networks
We present a simple model of a production network in which firms are linked by supplier-customer relationships involving extension of trade-credit. Our aim is to identify the minimal set of mechanisms which reproduce qualitatively the main stylized facts of industrial demography, such as firms' size distribution, and, at the same time, the correlation, over time and across firms, of output, growth and bankruptcies. The behavior of aggregate variables can be traced back to the direct firm-firm interdependence. In this paper, we assume that the number of firms is constant and the network has a periodic static structure. But the framework allows further extensions to investigate which network structures are more robust against domino effects and, if the network is let to evolve in time, which structures emerge spontaneously, depending on the individual strategies for orders and delivery
An economic and financial exploratory
This paper describes the vision of a European Exploratory for economics and finance using an interdisciplinary consortium of economists, natural scientists, computer scientists and engineers, who will combine their expertise to address the enormous challenges of the 21st century. This Academic Public facility is intended for economic modelling, investigating all aspects of risk and stability, improving financial technology, and evaluating proposed regulatory and taxation changes. The European Exploratory for economics and finance will be constituted as a network of infrastructure, observatories, data repositories, services and facilities and will foster the creation of a new cross-disciplinary research community of social scientists, complexity scientists and computing (ICT) scientists to collaborate in investigating major issues in economics and finance. It is also considered a cradle for training and collaboration with the private sector to spur spin-offs and job creations in Europe in the finance and economic sectors. The Exploratory will allow Social Scientists and Regulators as well as Policy Makers and the private sector to conduct realistic investigations with real economic, financial and social data. The Exploratory will (i) continuously monitor and evaluate the status of the economies of countries in their various components, (ii) use, extend and develop a large variety of methods including data mining, process mining, computational and artificial intelligence and every other computer and complex science techniques coupled with economic theory and econometric, and (iii) provide the framework and infrastructure to perform what-if analysis, scenario evaluations and computational, laboratory, field and web experiments to inform decision makers and help develop innovative policy, market and regulation designs. Graphical abstrac
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