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Search Results: 1 - 10 of 130886 matches for " V. Carbone "
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Scaling exponents of the velocity structure functions in the interplanetary medium
V. Carbone
Annales Geophysicae (ANGEO) , 2003,
Abstract: We analyze the scaling exponents of the velocity structure functions, obtained from the velocity fluctuations measured in the interplanetary space plasma. Using the expression for the energy transfer rate which seems the most relevant in describing the evolution of the pseudo-energy densities in the interplanetary medium, we introduce an energy cascade model derived from a simple fragmentation process, which takes into account the intermittency effect. In the absence and in the presence of the large-scale magnetic field decorrelation effect the model reduces to the fluid and the hydromagnetic p-model, respectively. We show that the scaling exponents of the q-th power of the velocity structure functions, as obtained by the model in the absence of the decorrelation effect, furnishes the best-fit to the data analyzed from the Voyager 2 velocity field measurements at 8.5 AU. Our results allow us to hypothesize a new kind of scale-similarity for magnetohydrodynamic turbulence when the decorrelation effect is at work, related to the fourth-order velocity structure function.
Cancellation exponents and multifractal scaling laws in the solar wind magnetohydrodynamic turbulence
V. Carbone,R. Bruno
Annales Geophysicae (ANGEO) , 2003,
Abstract: Some signed measures in turbulence are found to be sign-singular, that is their sign reverses continuously on arbitrary finer scales with a reduction of the cancellation between positive and negative contributions. The strength of the singularity is characterized by a scaling exponent κ, the cancellation exponent. In the present study by using some turbulent samples of the velocity field obtained from spacecraft measurements in the interplanetary medium, we show that sign-singularity is present everywhere in low-frequency turbulent samples. The cancellation exponent can be related to the characteristic scaling laws of turbulence. Differences in the values of κ, calculated in both high- and low-speed streams, allow us to outline some physical differences in the samples with different velocities.
Scaling properties of the Lyman--$α$ forest
S. Savaglio,V. Carbone
Physics , 1996,
Abstract: We present some statistical features of the large number of \lya absorption lines detected in high redshift quasar spectra, obtained by using the multifractal approach. In the analysed sample of 12 QSO sight--lines, 11 show scaling behaviour with a crossover between two distinct regimes: a non-homogeneous regime at small scales and a homogeneous regime at large scales. The correlation length shows a redshift dependence, suggesting that the \lya forest can be an intermediate phenomenon between a strongly inhomogeneous galaxy distribution in the local Universe and a homogeneous initial mass distribution.
A note on shell models for MHD Turbulence
P. Giuliani,V. Carbone
Physics , 1998, DOI: 10.1209/epl/i1998-00386-y
Abstract: We investigate the time evolution of two different (GOY-like) shell models which have been recently proposed to describe the gross features of MHD turbulence. We see that, even if they are formally of the same type sharing with MHD equations quadratic couplings and similar conserved quantities, fundamental differences exist which are related to the ideal invariants.
The complex dynamics of the seasonal component of USA's surface temperature
A. Vecchio, V. Capparelli,V. Carbone
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2010,
Abstract: The dynamics of the climate system has been investigated by analyzing the complex seasonal oscillation of monthly averaged temperatures recorded at 1167 stations covering the whole USA. We found the presence of an orbit-climate relationship on time scales remarkably shorter than the Milankovitch period {related to the nutational forcing}. The relationship manifests itself through occasional destabilization of the phase of the seasonal component due to the local changing of balance between direct insolation and the net energy received by the Earth. Quite surprisingly, we found that the local intermittent dynamics is modulated by a periodic component of about 18.6 yr due to the nutation of the Earth, which represents the main modulation of the Earth's precession. The global effect in the last century results in a cumulative phase-shift of about 1.74 days towards earlier seasons, in agreement with the phase shift expected from the Earth's precession. The climate dynamics of the seasonal cycle can be described through a nonlinear circle-map, indicating that the destabilization process can be associated to intermittent transitions from quasi-periodicity to chaos.
The complex dynamics of the seasonal component of USA's surface temperature
A. Vecchio,V. Capparelli,V. Carbone
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2010, DOI: 10.5194/acp-10-9657-2010
Abstract: The dynamics of the climate system has been investigated by analyzing the complex seasonal oscillation of monthly averaged temperatures recorded at 1167 stations covering the whole USA. We found the presence of an orbit-climate relationship on time scales remarkably shorter than the Milankovitch period {related to the nutational forcing}. The relationship manifests itself through occasional destabilization of the phase of the seasonal component due to the local changing of balance between direct insolation and the net energy received by the Earth. Quite surprisingly, we found that the local intermittent dynamics is modulated by a periodic component of about 18.6 yr due to the nutation of the Earth, which represents the main modulation of the Earth's precession. The global effect in the last century results in a cumulative phase-shift of about 1.74 days towards earlier seasons, in agreement with the phase shift expected from the Earth's precession. The climate dynamics of the seasonal cycle can be described through a nonlinear circle-map, indicating that the destabilization process can be associated to intermittent transitions from quasi-periodicity to chaos.
A critical assessment on Kassapoglou's statistical model for composites fatigue
M. Ciavarella,V. Vinogradov,G. Carbone
Physics , 2013,
Abstract: Kassapoglou recently proposed a model for fatigue of composite materials which seems to suggest that fatigue SN curve can be entirely predicted on the basis of the statistical distribution of static strengths. The original abstract writes "Expressions for the cycles to failure as a function of R ratio are derived. These expressions do not require any curve fitting and do not involve any experimentally determined parameters. The fatigue predictions do not require any fatigue tests for calibration". These surprisingly ambitious claims and attractive results deserve careful scrutiny. We contend that the results seem to be due to a number of approximations and incorrect derivations, and one particular misleading assumption, which make the model not conform to a fatigue testing in a given specimen with resulting SN curve distribution. The quantitative agreement of some predictions (the scatter of distribution of fatigue lives being close to the mode value found in typical composites of aeronautical interest in the large Navy database) should not motivate any enthusiasm. It is believed that a proper statistical treatment of the fatigue process should not make wear-out constants disappear, and hence the SN curves would depend on them, and not just on scatter of static data. These serious concerns explain the large discrepancies found by 3 independent studies which tried to apply Kassapoglou's model to composite fatigue data, and to other well known results.
Yaglom law in the expanding solar wind
G. Gogoberidze,S. Perri,V. Carbone
Physics , 2013, DOI: 10.1088/0004-637X/769/2/111
Abstract: We study the Yaglom law, which relates the mixed third order structure function to the average dissipation rate of turbulence, in a uniformly expanding solar wind by using the two scales expansion model of magnetohydrodynamic (MHD) turbulence. We show that due to the expansion of the solar wind two new terms appear in the Yaglom law. The first term is related to the decay of the turbulent energy by nonlinear interactions, whereas the second term is related to the non-zero cross-correlation of the Els\"asser fields. Using magnetic field and plasma data from WIND and Helios 2 spacecrafts, we show that at lower frequencies in the inertial range of MHD turbulence the new terms become comparable to Yaglom's third order mixed moment, and therefore they cannot be neglected in the evaluation of the energy cascade rate in the solar wind.
Multiple Interactions between Peroxisome Proliferators-Activated Receptors and the Ubiquitin-Proteasome System and Implications for Cancer Pathogenesis
Davide Genini,Giuseppina M. Carbone,Carlo V. Catapano
PPAR Research , 2008, DOI: 10.1155/2008/195065
Abstract: The peroxisome proliferator-activated receptors (PPAR) ,/, and are ligand-activated nuclear receptors involved in a number of physiological processes, including lipid and glucose homeostasis, inflammation, cell growth, differentiation, and death. PPAR agonists are used in the treatment of human diseases, like type 2 diabetes and dyslipidemia, and PPARs appear as promising therapeutic targets in other conditions, including cancer. A better understanding of the functions and regulation of PPARs in normal and pathological processes is of primary importance to devise appropriate therapeutic strategies. The ubiquitin-proteasome system (UPS) plays an important role in controlling level and activity of many nuclear receptors and transcription factors. PPARs are subjected to UPS-dependent regulation. Interestingly, the three PPAR isotypes are differentially regulated by the UPS in response to ligand-dependent activation, a phenomenon that may be intrinsically connected to their distinct cellular functions and behaviors. In addition to their effects ongene expression, PPARs appear to affect protein levels and downstream pathways also by modulating the activity of the UPS in target-specific manners. Here we review the current knowledge of the interactions between the UPS and PPARs in light of the potential implications for their effects on cell fate and tumorigenesis.
Chondroma of the hand with osteoid formation: first case report
Arena V, Pennacchia I, Vecchio FM, Carbone A
International Medical Case Reports Journal , 2011, DOI: http://dx.doi.org/10.2147/IMCRJ.S20727
Abstract: ndroma of the hand with osteoid formation: first case report Case report (2468) Total Article Views Authors: Arena V, Pennacchia I, Vecchio FM, Carbone A Published Date July 2011 Volume 2011:4 Pages 47 - 48 DOI: http://dx.doi.org/10.2147/IMCRJ.S20727 Vincenzo Arena, Ilaria Pennacchia, Fabio Maria Vecchio, Arnaldo Carbone Institute of Pathology, Catholic University of Sacred Heart, Rome, Italy Abstract: Chondroma is the most common neoplasia of the hand. Histologically, it consists of lobules of normal-appearing hyaline cartilage showing a lobular arrangement. To the best of our knowledge, this is the first reported case of chondroma of the hand in which, interestingly, osteoid production was observed.
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