13,901 research outputs found
Asteroseismic Theory of Rapidly Oscillating Ap Stars
This paper reviews some of the important advances made over the last decade
concerning theory of roAp stars.Comment: 9 pages, 5 figure
A Note on Tachyon Moduli and Closed Strings
The collective behavior of the SL(2,R) covariant brane states of non-critical
c=1 string theory found in a previous work, is studied in the Fermi liquid
approximation. It is found that such states mimick the coset WZW model, whereas
only by further restrictions one recovers the double-scaling limit which was
purported to be equivalent to closed string models. Another limit is proposed,
inspired by the tachyon condensation ideas, where the spectrum is the same of
two-dimensional string theory. We close by noting some strange connections
between vacuum states of the theory in their different interpretations.Comment: PDFLaTeX, 17 pages, 2 figures; Section 2 rewritten, several fixes
throughout the text to improve clarit
Impact of micro-telluric lines on precise radial velocities and its correction
Context: In the near future, new instruments such as ESPRESSO will arrive,
allowing us to reach a precision in radial-velocity measurements on the order
of 10 cm/s. At this level of precision, several noise sources that until now
have been outweighed by photon noise will start to contribute significantly to
the error budget. The telluric lines that are not neglected by the masks for
the radial velocity computation, here called micro-telluric lines, are one such
noise source. Aims: In this work we investigate the impact of micro-telluric
lines in the radial velocities calculations. We also investigate how to correct
the effect of these atmospheric lines on radial velocities. Methods: The work
presented here follows two parallel lines. First, we calculated the impact of
the micro-telluric lines by multiplying a synthetic solar-like stellar spectrum
by synthetic atmospheric spectra and evaluated the effect created by the
presence of the telluric lines. Then, we divided HARPS spectra by synthetic
atmospheric spectra to correct for its presence on real data and calculated the
radial velocity on the corrected spectra. When doing so, one considers two
atmospheric models for the synthetic atmospheric spectra: the LBLRTM and TAPAS.
Results: We find that the micro-telluric lines can induce an impact on the
radial velocities calculation that can already be close to the current
precision achieved with HARPS, and so its effect should not be neglected,
especially for future instruments such as ESPRESSO. Moreover, we find that the
micro-telluric lines' impact depends on factors, such as the radial velocity of
the star, airmass, relative humidity, and the barycentric Earth radial velocity
projected along the line of sight at the time of the observation.Comment: Accepted in A&
Fiscal sustainability and policy implications for the euro area.
In this paper we examine the sustainability of euro area public finances against the backdrop of population ageing. We critically assess the widely used projections of the Working Group on Ageing Populations (AWG) of the EU's Economic Policy Committee and argue that ageing costs may be higher than projected in the AWG reference scenario. Taking into account adjusted headline estimates for ageing costs, largely based upon the sensitivity analysis carried out by the AWG, we consider alternative indicators to quantify sustainability gaps for euro area countries. With respect to the policy implications, we assess the appropriateness of different budgetary strategies to restore fiscal sustainability taking into account intergenerational equity. Our stylised analysis based upon the lifetime contribution to the government's primary balance of different generations suggests that an important degree of pre-funding of the ageing costs is necessary to avoid shifting the burden of adjustment in a disproportionate way to future generations. For many euro area countries this implies that the medium-term targets defined in the context of the revised stability and growth pact would ideally need to be revised upwards to significant surpluses.Population Ageing ; Fiscal Sustainability ; Generational Accounting ; Medium-term Objectives for Fiscal Policy
Tomographic Characterization of Three-Qubit Pure States with Only Two-Qubit Detectors
A tomographic process for three-qubit pure states using only pairwise
detections is presented.Comment: 3 pages; revtex4; v2: the focus on tomography was emphasized and the
experimental procedure detailed; v3: the text was improved in clarity, some
mistakes were correcte
A multicriteria approach for a phased design of water distribution networks
Published13th Computer Control for Water Industry Conference, CCWI 2015Water distribution networks are key infrastructure that provide essential water supply to communities. Planning water distribution networks involves many actors, including water companies, governments, environmentalists, consumers and financing institutions, and they tend to have conflicting perspectives. This work proposes a multi-criteria decision analysis (MCDA) as a useful tool for providing decision support in such circumstances. A phased planning horizon scheme is proposed that identifies the design for the first time interval while considering possible future conditions that the network might have to cope with. The results identify the best ranked phased design solutions.This paper is based on research conducted under the DESAFIO project (www.desafioglobal.org). DESAFIO is
funded by the Seventh Framework Programme of the European Union for research, technological development and
demonstration under grant agreement no. 320303. The information contained in this work reflects only the opinion
of the authors and the European Union is not responsible for the use which may be made of the information
contained therein
The Geometry of Entanglement Sudden Death
In open quantum systems, entanglement can vanish faster than coherence. This
phenomenon is usually called sudden death of entanglement. In this paper sudden
death of entanglement is discussed from a geometrical point of view, in the
context of two qubits. A classification of possible scenarios is presented,
with important known examples classified. Theoretical and experimental
construction of other examples is suggested as well as large dimensional and
multipartite versions of the effect.Comment: 6 pages, 2 figures, references added, initial paragraph corrected,
sectioning adopted, some parts rewritten; accepted by New J. Phy
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