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Search Results: 1 - 10 of 325373 matches for " S. Aghion "
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The Relationship Between Health and Growth: When Lucas Meets Nelson-Phelps
Philippe Aghion,Peter Howitt,Fabrice Murtin
Review of Economics and Institutions , 2011, DOI: 10.5202/rei.v2i1.22
Abstract: This paper revisits the relationship between health and growth in light of modern endogenous growth theory. We propose a unified framework that encompasses the growth effects of both the rate of improvement of health and the level of health. Based on cross-country regressions over the period 1960-2000, where we instrument for both variables, we find that a higher initial level and a higher rate of improvement in life expectancy both have a significantly positive impact on per capita GDP growth. Then, restricting attention to OECD countries, we find supportive evidence that only the reduction in mortality below age forty generates productivity gains, which in turn may explain why the positive correlation between health and growth in cross-OECD country regressions appears to have weakened since 1960.
From the area under the Bessel excursion to anomalous diffusion of cold atoms
E. Barkai,E. Aghion,D. A. Kessler
Physics , 2014, DOI: 10.1103/PhysRevX.4.021036
Abstract: Levy flights are random walks in which the probability distribution of the step sizes is fat-tailed. Levy spatial diffusion has been observed for a collection of ultra-cold Rb atoms and single Mg+ ions in an optical lattice. Using the semiclassical theory of Sisyphus cooling, we treat the problem as a coupled Levy walk, with correlations between the length and duration of the excursions. The problem is related to the area under Bessel excursions, overdamped Langevin motions that start and end at the origin, constrained to remain positive, in the presence of an external logarithmic potential. In the limit of a weak potential, the Airy distribution describing the areal distribution of the Brownian excursion is found. Three distinct phases of the dynamics are studied: normal diffusion, Levy diffusion and, below a certain critical depth of the optical potential, x~ t^{3/2} scaling. The focus of the paper is the analytical calculation of the joint probability density function from a newly developed theory of the area under the Bessel excursion. The latter describes the spatiotemporal correlations in the problem and is the microscopic input needed to characterize the spatial diffusion of the atomic cloud. A modified Montroll-Weiss (MW) equation for the density is obtained, which depends on the statistics of velocity excursions and meanders. The meander, a random walk in velocity space which starts at the origin and does not cross it, describes the last jump event in the sequence. In the anomalous phases, the statistics of meanders and excursions are essential for the calculation of the mean square displacement, showing that our correction to the MW equation is crucial, and points to the sensitivity of the transport on a single jump event. Our work provides relations between the statistics of velocity excursions and meanders and that of the diffusivity.
Pulse width Modulation Command Systems Used for the Optimization of Three Phase Inverters
Advances in Electrical and Computer Engineering , 2009,
Abstract: This paper deals with a novel pulse width modulation (PWM) switching strategy for a voltage source inverter through carrier modification. The proposed discontinuous sine carrier PWM (DPWM1) method, which uses two modified sine waves, has a better spectral quality and a higher fundamental component. This improved waveform has been derived from the original sine PWM technique through the addition of the 17-percent third-harmonic component to the original sine reference.
Pourquoi réformer les universités européennes ?
Mathias Dewatripont,Philippe Aghion,Caroline Hoxby,Andreu Mas-Colell
Pyramides : Revue du Centre d'Etudes et de Recherches en Administration Publique , 2011,
Abstract: Récemment, les classements internationaux qui ont été publiés indiquent que l’écart de performance entre les universités européennes et américaines est grand, et en particulier que les meilleures universités européennes se retrouvent bien derrière les meilleures universités américaines. L’indice de performance d’un pays que nous avons établi, utilisant le classement de Shanghai, confirme que malgré la bonne performance de certains pays, l’Europe dans son ensemble est nettement à la tra ne de l’Amérique. La raison de cette situation, qui contribue au déficit de croissance économique de l’Europe, est double. Premièrement, l’Europe investit trop peu dans l’éducation supérieure. Les dépenses totales privées et publiques en éducation supérieure dans l’Europe des 25 atteignent à peine 1.3 % du PIB, contre 3.3 % aux Etats-Unis. Cela se traduit par des dépenses moyennes de moins de 10.000 € par étudiant dans l’Europe des 25, et par plus de 35.000 € aux Etats-Unis. Deuxièmement, les universités européennes souffrent d’une gouvernance inadéquate, d’autonomie insuffisante et d’incitations souvent perverses. Notre enquête sur les universités européennes montre que les deux facteurs contribuent à la faible performance de l’Europe et qu’une réforme devrait avoir lieu sur les deux fronts, parce que l’autonomie augmente aussi l’efficacité des dépenses.
Penetrating Brain Injury after Suicide Attempt with Speargun
John R. Williams,Daniel Aghion,Wael F. Asaad
Frontiers in Neurology , 2014, DOI: 10.3389/fneur.2014.00113
Abstract: Penetrating cranial injury by mechanisms other than are exceedingly rare, and so strategies and guidelines for the management of PBI are largely informed by data from higher-velocity penetrating injuries. Here we present a case of penetrating brain injury by the low velocity mechanism of a harpoon from an underwater fishing speargun in an attempted suicide by a 56-year-old Caucasian male. The case raised a number of interesting points in management of lower-velocity penetrating brain injury (LVPBI), including benefit in delaying foreign body removal to allow for tamponade; the importance of history taking in establishing the social/legal significance of the events surrounding the injury; the use of cerebral angiogram in all cases of PBI; advantages of using DECT to reduce artifact when available; and antibiotic prophylaxis in the context of idiosyncratic histories of usage of penetrating objects before coming in contact with the intracranial environment. We present here the management of the case in full along with an extended discussion and review of existing literature regarding key points in management of LVPBI vs. higher velocity forms of intracranial injury.
Fluctuations of ring polymers
Shlomi Medalion,Erez Aghion,Hagai Meirovitch,Eli Barkai,David A. Kessler
Physics , 2015,
Abstract: We present an exact solution for the distribution of sample averaged monomer to monomer distance of ring polymers. For non-interacting and weakly-interacting models these distributions correspond to the distribution of the area under the reflected Bessel bridge and the Bessel excursion respectively, and are shown to be identical in dimension d greater or equal 2. A symmetry of the problem reveals that dimension d and 4 minus d are equivalent, thus the celebrated Airy distribution describing the areal distribution of the one dimensional Brownian excursion describes also a polymer in three dimensions. For a self-avoiding polymer in dimension d we find numerically that the fluctuations of the scaled averaged distance are nearly identical in dimensions 2 and 3, and are well described to a first approximation by the non-interacting excursion model in dimension 5.
Prospects for measuring the gravitational free-fall of antihydrogen with emulsion detectors
AEgIS Collaboration,S. Aghion,O. Ahlén,C. Amsler,A. Ariga,T. Ariga,A. S. Belov,G. Bonomi,P. Br?unig,J. Bremer,R. S. Brusa,L. Cabaret,C. Canali,R. Caravita,F. Castelli,G. Cerchiari,S. Cialdi,D. Comparat,G. Consolati,J. H. Derking,S. Di Domizio,L. Di Noto,M. Doser,A. Dudarev,A. Ereditato,R. Ferragut,A. Fontana,P. Genova,M. Giammarchi,A. Gligorova,S. N. Gninenko,S. Haider,J. Harasimovicz,S. D. Hogan,T. Huse,E. Jordan,L. V. J?rgensen,T. Kaltenbacher,J. Kawada,A. Kellerbauer,M. Kimura,A. Knecht,D. Krasnicky,V. Lagomarsino,A. Magnani,S. Mariazzi,V. A. Matveev,F. Moia,G. Nebbia,P. Nédélec,M. K. Oberthaler,N. Pacifico,V. Petrácek,C. Pistillo,F. Prelz,M. Prevedelli,C. Regenfus,C. Riccardi,O. R?hne,A. Rotondi,H. Sandaker,P. Scampoli,A. Sosa,J. Storey,M. A. Subieta Vasquez,M. Spacek,G. Testera,D. Trezzi,R. Vaccarone,C. P. Welsch,S. Zavatarelli
Physics , 2013, DOI: 10.1088/1748-0221/8/08/P08013
Abstract: The main goal of the AEgIS experiment at CERN is to test the weak equivalence principle for antimatter. AEgIS will measure the free-fall of an antihydrogen beam traversing a moir\'e deflectometer. The goal is to determine the gravitational acceleration g for antihydrogen with an initial relative accuracy of 1% by using an emulsion detector combined with a silicon micro-strip detector to measure the time of flight. Nuclear emulsions can measure the annihilation vertex of antihydrogen atoms with a precision of about 1 - 2 microns r.m.s. We present here results for emulsion detectors operated in vacuum using low energy antiprotons from the CERN antiproton decelerator. We compare with Monte Carlo simulations, and discuss the impact on the AEgIS project.
Annihilation of low energy antiprotons in silicon
S. Aghion,O. Ahlén,A. S. Belov,G. Bonomi,P. Br?unig,J. Bremer,R. S. Brusa,G. Burghart,L. Cabaret,M. Caccia,C. Canali,R. Caravita,F. Castelli,G. Cerchiari,S. Cialdi,D. Comparat,G. Consolati,J. H. Derking,S. Di Domizio,L. Di Noto,M. Doser,A. Dudarev,R. Ferragut,A. Fontana,P. Genova,M. Giammarchi,A. Gligorova,S. N. Gninenko,S. Haider,J. Harasimowicz,T. Huse,E. Jordan,L. V. J?rgensen,T. Kaltenbacher,A. Kellerbauer,A. Knecht,D. Krasnicky,V. Lagomarsino,A. Magnani,S. Mariazzi,V. A. Matveev,F. Moia,G. Nebbia,P. Nédélec,N. Pacifico,V. Petrácek,F. Prelz,M. Prevedelli,C. Regenfus,C. Riccardi,O. R?hne,A. Rotondi,H. Sandaker,A. Sosa,M. A. Subieta Vasquez,M. ?pacek,G. Testera,C. P. Welsch,S. Zavatarelli
Physics , 2013,
Abstract: The goal of the AE$\mathrm{\bar{g}}$IS experiment at the Antiproton Decelerator (AD) at CERN, is to measure directly the Earth's gravitational acceleration on antimatter. To achieve this goal, the AE$\mathrm{\bar{g}}$IS collaboration will produce a pulsed, cold (100 mK) antihydrogen beam with a velocity of a few 100 m/s and measure the magnitude of the vertical deflection of the beam from a straight path. The final position of the falling antihydrogen will be detected by a position sensitive detector. This detector will consist of an active silicon part, where the annihilations take place, followed by an emulsion part. Together, they allow to achieve 1$%$ precision on the measurement of $\bar{g}$ with about 600 reconstructed and time tagged annihilations. We present here, to the best of our knowledge, the first direct measurement of antiproton annihilation in a segmented silicon sensor, the first step towards designing a position sensitive silicon detector for the AE$\mathrm{\bar{g}}$IS experiment. We also present a first comparison with Monte Carlo simulations (GEANT4) for antiproton energies below 5 MeV
Study of the Structural and Electrical Properties of Cr-Doped BiFeO3 Ceramic  [PDF]
S. S. Arafat, S. Ibrahim
Materials Sciences and Applications (MSA) , 2017, DOI: 10.4236/msa.2017.810051
Abstract: Multiferroic BiFe1-xCrxO3 (x = 0.2 and 0.4) ceramics were synthesized in a single phase. The effects of Cr3+ substitution on the crystal structure, dielectric permittivity and leakage current were investigated. Preliminary X-ray structural studies revealed that the samples had a rhombohedral perovskite crystal structure. The dielectric constant ε' significantly increased while the dielectric loss tanδ was substantially decreased with the increase in Cr3+ substitution. The temperature effect on the dielectric properties exhibited an anomaly corresponding to magneto-electric coupling in the samples and was shifted to lower temperatures with the increase in Cr3+ substitution. The leakage current density also reduced in magnitude with the increase in the Cr3+ substitution.
Degree Splitting of Root Square Mean Graphs  [PDF]
S. S. Sandhya, S. Somasundaram, S. Anusa
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.66086
Abstract: Let \"\" be an injective function. For a vertex labeling f, the induced edge labeling \"\" is defined by, \"\" or \"\"; then, the edge labels are distinct and are from \"\". Then f is called a root square mean labeling of G. In this paper, we prove root square mean labeling of some degree splitting graphs.
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