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Search Results: 1 - 10 of 603196 matches for " M. V. D'Agostino "
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Hydrogeomorphic processes and torrent control works on a large alluvial fan in the eastern Italian Alps
L. Marchi,M. Cavalli,V. D'Agostino
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2010,
Abstract: Alluvial fans are often present at the outlet of small drainage basins in alpine valleys; their formation is due to sediment transport associated with flash floods and debris flows. Alluvial fans are preferred sites for human settlements and are frequently crossed by transport routes. In order to reduce the risk for economic activities located on or near the fan and prevent loss of lives due to floods and debris flows, torrent control works have been extensively carried out on many alpine alluvial fans. Hazard management on alluvial fans in alpine regions is dependent upon reliable procedures to evaluate variations in the frequency and severity of hydrogeomorphic processes and the long-term performance of the torrent training works. An integrated approach to the analysis of hydrogeomorphic processes and their interactions with torrent control works has been applied to a large alluvial fan in the southern Carnic Alps (northeastern Italy). Study methods encompass field observations, interpretation of aerial photographs, analysis of historical documents, and numerical modelling of debris flows. The overall performance of control works implemented in the early decades of 20th century was satisfactory, and a reduction of hazardous events was recognised from features observed in the field and in aerial photographs, as well as from the analysis of historical records. The 2-D simulation of debris flows confirms these findings, indicating that debris flow deposition would not affect urban areas or main roads, even in the case of a high-magnitude event. Present issues in the management of the studied alluvial fan are representative of situations frequently found in the European Alps and deal with the need for maintenance of the control structures and the pressures for land use changes aimed at the economic exploitation of the fan surface.
On the reliability of negative heat capacity measurements
M. D'Agostino,R. Bougault,F. Gulminelli,M. Bruno,F. Cannata,Ph. Chomaz,F. Gramegna,I. Iori,N. Le Neindre,G. V. Margagliotti,A. Moroni,G. Vannini
Physics , 2001, DOI: 10.1016/S0375-9474(01)01287-8
Abstract: A global protocol for the thermostatistical analysis of hot nuclear sources is discussed. Within our method of minimization of variances we show that the abnormal kinetic energy fluctuation signal recently reported in different experimental data (M.D'Agostino et al.-Phys. Lett. B 473 (2000) 219, N. Le Neindre et al.- contr. to the XXXVIII Bormio Winter Meeting on Nucl. Phys. (2001) 404) is a genuine signal of a first order phase transition in a finite system.
Critical behaviors in central and peripheral collisions: a comparative analysis
M. D'Agostino,M. Bruno,F. Gulminelli,R. Bougault,F. Cannata,Ph. Chomaz,F. Gramegna,N. Le Neindre,G. V. Margagliotti,A. Moroni,G. Vannini,J. P. Wieleczko
Physics , 2002, DOI: 10.1016/S0375-9474(03)01541-0
Abstract: Quasi-projectile events from peripheral 35 A.MeV Au+ Au collisions are compared to central Au + C, Au + Cu and Au + Au events in the same range of excitation energy in terms of critical partitions and critical exponents. All the different data sets coherently point to a value E*c=4.5 A.MeV for the apparent critical excitation energy. The critical exponents tau, sigma are compatible with the observation of a liquid-gas phase transition for these systems.
Fluctuations of fragment observables
F. Gulminelli,M. D'Agostino
Physics , 2006, DOI: 10.1140/epja/i2006-10121-x
Abstract: This contribution presents a review of our present theoretical as well as experimental knowledge of different fluctuation observables relevant to nuclear multifragmentation. The possible connection between the presence of a fluctuation peak and the occurrence of a phase transition or a critical phenomenon is critically analyzed. Many different phenomena can lead both to the creation and to the suppression of a fluctuation peak. In particular, the role of constraints due to conservation laws and to data sorting is shown to be essential. From the experimental point of view, a comparison of the available fragmentation data reveals that there is a good agreement between different data sets of basic fluctuation observables, if the fragmenting source is of comparable size. This compatibility suggests that the fragmentation process is largely independent of the reaction mechanism (central versus peripheral collisions, symmetric versus asymmetric systems, light ions versus heavy ion induced reactions). Configurational energy fluctuations, that may give important information on the heat capacity of the fragmenting system at the freeze out stage, are not fully compatible among different data sets and require further analysis to properly account for Coulomb effects and secondary decays. Some basic theoretical questions, concerning the interplay between the dynamics of the collision and the fragmentation process, and the cluster definition in dense and hot media, are still open and are addressed at the end of the paper. A comparison with realistic models and/or a quantitative analysis of the fluctuation properties will be needed to clarify in the next future the nature of the transition observed from compound nucleus evaporation to multi-fragment production.
Isotopic composition of fragments in multifragmentation of very large nuclear systems: effects of the chemical equilibrium
P. M. Milazzo,A. S. Botvina,G. Vannini,M. Bruno,N. Colonna,M. D'Agostino,F. Gramegna,I. Iori,G. V. Margagliotti,P. F. Mastinu,A. Moroni,R. Rui
Physics , 2002, DOI: 10.1103/PhysRevC.66.021601
Abstract: Studies on the isospin of fragments resulting from the disassembly of highly excited large thermal-like nuclear emitting sources, formed in the ^{197}Au + ^{197}Au reaction at 35 MeV/nucleon beam energy, are presented. Two different decay systems (the quasiprojectile formed in midperipheral reactions and the unique source coming from the incomplete fusion of projectile and target in the most central collisions) were considered; these emitting sources have the same initial N/Z ratio and excitation energy (E^* ~= 5--6 MeV/nucleon), but different size. Their charge yields and isotopic content of the fragments show different distributions. It is observed that the neutron content of intermediate mass fragments increases with the size of the source. These evidences are consistent with chemical equilibrium reached in the systems. This fact is confirmed by the analysis with the statistical multifragmentation model.
Negative heat capacity in the critical region of nuclear fragmentation: an experimental evidence of the liquid-gas phase transition
M. D'Agostino,F. Gulminelli,Ph. Chomaz,M. Bruno,F. Cannata,R. Bougault,N. Colonna,F. Gramegna,I. Iori,N. Le Neindre,G. V. Margagliotti,P. F. Mastinu,P. M. Milazzo,A. Moroni,G. Vannini
Physics , 1999, DOI: 10.1016/S0370-2693(99)01486-0
Abstract: An experimental indication of negative heat capacity in excited nuclear systems is inferred from the event by event study of energy fluctuations in $Au$ quasi-projectile sources formed in $Au+Au$ collisions at 35 A.MeV. The excited source configuration is reconstructed through a calorimetric analysis of its de-excitation products. Fragment partitions show signs of a critical behavior at about 5 A.MeV excitation energy. In the same energy range the heat capacity shows a negative branch providing a direct evidence of a first order liquid gas phase transition.
A arquitetura, o corpo e o espelho sobre a beleza e o tempo na arte do Renascimento e em nossos dias
D'Agostino, Mário Henrique Sim?o;
Tempo Social , 2003, DOI: 10.1590/S0103-20702003000100007
Abstract: the revival of the old ideal of "eternal fame" and "perpetuity" in art allows for a new conceptual framing of the classical principle of mimesis, in the renaissance. asserting the preeminence of architecture over all the other arts, various renaissance papers link the making of beautiful works to the longevity of the buildings (chrysolaras, alberti, filarete, cesariano, among others). the curatorship and the exemplary value of the monuments, coordinated to the norm of imitating the antichi, bring about different doctrinarian positions on the meaning of time in art to regulate classicisms up to the 18th century. on the other hand, by looking back on the challenges issued then allows one to make a more removed and critical appraisal on the diffuse "cult" of time and beauty, currently in fashion.
Comment on "Partial energies fluctuations and negative heat capacities" by X. Campi et al
Ph. Chomaz,F. Gulminelli,M. D'Agostino
Physics , 2004,
Abstract: Studying the energy partioning published in nucl-th/0406056v2 we show that the presented results do not fulfill the sum rule due to energy conservation. The observed fluctuations of the energy conservation test point to a numerical problem. Moreover, analysis of the binding energies show that the fragment recognition algorithm adopted by Campi et al. leads with a sizeable probability to fragments containing up to the total mass even for excitation energies as large as 3/4 of the total binding. This surprising result points to another problem since the published inter-fragment energy is not zero while a unique fragment is present. This problem may be due to either the fragment recognition algorithm or to the definition of the inter and intra-fragment energy. These numerical inconsistencies should be settled before any conclusion on the physics can be drawn.
Tracking energy fluctuations from fragment partitions in the Lattice Gas model
F. Gulminelli,Ph. Chomaz,M. D'Agostino
Physics , 2004, DOI: 10.1103/PhysRevC.72.064618
Abstract: Partial energy fluctuations are known tools to reconstruct microcanonical heat capacities. For experimental applications, approximations have been developed to infer fluctuations at freeze out from the observed fragment partitions. The accuracy of this procedure as well as the underlying independent fragment approximation is under debate already at the level of equilibrated systems. Using a well controlled computer experiment, the Lattice Gas model, we critically discuss the thermodynamic conditions under which fragment partitions can be used to reconstruct the thermodynamics of an equilibrated system.
Is Postmastectomy Radiation Therapy Indicated in Patients with Close or Positive Margins?  [PDF]
Michelle L. Bryan, Ralph B. DAgostino, Doris R. Brown, Marissa M. Howard-McNatt
Advances in Breast Cancer Research (ABCR) , 2016, DOI: 10.4236/abcr.2016.52007
Abstract: Background: The indications for Post Mastectomy Radiation Therapy (PMRT) for positive or close margins are unclear. We examined the indications for PMRT in mastectomy patients with close or positive margins and determined patterns for relapse and survival. Methods: The pathology reports of 610 patients treated with a mastectomy from 1999-2012 were reviewed. Of these, 72 patients had a positive or <2 mm margin. Demographic, tumor characteristics, treatments and survival were compared between women treated with and without PMRT. Results: The mean follow up was 4.1 years. Patients who received PMRT were younger (p = 0.03) and more likely to receive chemotherapy (p = 0.03). Patients with lymphovascular invasion (LVI) were more likely to undergo PMRT (p = 0.02). Seven patients who did not receive PMRT recurred. There was no correlation with locoregional failure. The disease free survival was better in the PMRT group (p = 0.03), but the overall survival was the same. Conclusion: We found that women with a close or positive margin who were younger, had LVI, and who received chemotherapy received PMRT. The disease free survival was better in the PMRT cohort, but the overall survival was similar. Long-term follow up of patients is warranted to see if PMRT offers a survival advantage.
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