190 research outputs found

    The Potential of Continuous, Local Atomic Clock Measurements for Earthquake Prediction and Volcanology

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    Modern optical atomic clocks along with the optical fiber technology currently being developed can measure the geoid, which is the equipotential surface that extends the mean sea level on continents, to a precision that competes with existing technology. In this proceeding, we point out that atomic clocks have the potential to not only map the sea level surface on continents, but also look at variations of the geoid as a function of time with unprecedented timing resolution. The local time series of the geoid has a plethora of applications. These include potential improvement in the predictions of earthquakes and volcanoes, and closer monitoring of ground uplift in areas where hydraulic fracturing is performed.Comment: 7 pages, one figure, proceeding for ICNFP 201

    Numerical Simulations of Oscillating Soliton Stars: Excited States in Spherical Symmetry and Ground State Evolutions in 3D

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    Excited state soliton stars are studied numerically for the first time. The stability of spherically symmetric S-branch excited state oscillatons under radial perturbations is investigated using a 1D code. We find that these stars are inherently unstable either migrating to the ground state or collapsing to black holes. Higher excited state configurations are observed to cascade through intermediate excited states during their migration to the ground state. This is similar to excited state boson stars. Ground state oscillatons are then studied in full 3D numerical relativity. Finding the appropriate gauge condition for the dynamic oscillatons is much more challenging than in the case of boson stars. Different slicing conditions are explored, and a customized gauge condition that approximates polar slicing in spherical symmetry is implemented. Comparisons with 1D results and convergence tests are performed. The behavior of these stars under small axisymmetric perturbations is studied and gravitational waveforms are extracted. We find that the gravitational waves damp out on a short timescale, enabling us to obtain the complete waveform. This work is a starting point for the evolution of real scalar field systems with arbitrary symmetries.Comment: 12 pages, 11 figures, typos corrected, includes referee input, references corrected, published versio

    ROMANIA'S REAL CONVERGENCE TO THE EUROPEAN UNION Dragos Mihai Ungureanu , Permanent Representation of Romania to the European Union Ruxandra Dana Vilag, Romanian-American University Bucharest George Horia Ionescu, Romanian-American University Bucharest Florian Bogdan Stoian, “Lucian Blaga†University of Sibiu

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    In the process of European integration, switching in 1999 to the third stageof Economic and Monetary Union, has intensified the need to coordinate economic andsectoral policies of the Member States. The process of coordination is necessary toharmonize national economic policy objectives in order to minimize the negative impactof economic policy measures taken by some member countries to other member countriesand reduce the temptation for Member States to have behavior riders. Real Convergenceis an essential goal of Romanian integration into the European Union. Attenuation of thedevelopment gaps maintained between Romania and the EU can not be achieved solelythrough the use of market forces. Economic transformations occurring globally andincreased risk aversion contributed to a signifiant reduction of capital flows to Romania,increased pressures upon exchange rate.Real convergence, nominal convergence, integration, European Union

    FINANCIAL CONTAGION AND INVESTORS BEHAVIOR

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    International capital markets, in general, seem to be volatile markets, influenced bymany factors, a phenomenon that affects both developed markets, as well as least developed, withemerging market economies suffering most because of this. It is clear, however, that volatility willremain for as long as it is delayed the adoption of specific measures at national and internationalfinancial architecture level, measures that may be necessary to reduce these risks, to limit theirimpact, and that the question financial market can relapse in a manner as efficiently as possible.investor behaviour, financial crisis, rational investor, irational investor, financial contagion

    ASSESING THE IMPLEMENTATION OF REAL CONVERGENCE IN ROMANIA

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    The convergence is an essential objective of the integration process of Romania in the European Union. Minimizing gaps in the level of development that arise between Romania and the average European Union can not be achieved solely through the use of marconvergence, European Union, real convergence

    Pitfalls and problems encountered in rat model sciatic nerve surgery

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    When learning the basics of microsurgery, a trainee must be equipped with patience and perseverance in order to evolve. One must have the ground knowledge when it comes to peripheral nerve injury and nerve regeneration process in order to fully understand that the technique is vital for the outcome and final results. Furthermore, a trainee must practice on non-living tissue before performing successful in vivo operations and even in this case, one may be confronted with problems regarding the surgical technique. [1] The following article aims to reveal the main problems/mistakes when performing sciatic nerve surgery in an in vivo experimental model and the solutions for these problems

    Atomic clocks as a tool to monitor vertical surface motion

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    Atomic clock technology is advancing rapidly, now reaching stabilities of Δf/f∼10−18\Delta f/f \sim 10^{-18}, which corresponds to resolving 11 cm in equivalent geoid height over an integration timescale of about 7 hours. At this level of performance, ground-based atomic clock networks emerge as a tool for monitoring a variety of geophysical processes by directly measuring changes in the gravitational potential. Vertical changes of the clock's position due to magmatic, volcanic, post-seismic or tidal deformations can result in measurable variations in the clock tick rate. As an example, we discuss the geopotential change arising due to an inflating point source (Mogi model), and apply it to the Etna volcano. Its effect on an observer on the Earth's surface can be divided into two different terms: one purely due to uplift and one due to the redistribution of matter. Thus, with the centimetre-level precision of current clocks it is already possible to monitor volcanoes. The matter redistribution term is estimated to be 2-3 orders of magnitude smaller than the uplift term, and should be resolvable when clocks improve their stability to the sub-millimetre level. Additionally, clocks can be compared over distances of thousands of kilometres on a short-term basis (e.g. hourly). These clock networks will improve our ability to monitor periodic effects with long-wavelength like the solid Earth tide.Comment: 11 pages, 5 figures, accepted as express letter in the Geophysical Journal Internationa
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