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341 results on '"Caccamo C."'

102. Theoretical investigations of simple model protein solutions.

Author

Caccamo, C., Pellicane, G., and Costa, D.

Subjects
*THERMODYNAMICS, *INTEGRAL equations, *PHASE diagrams
Abstract

Thermodynamically self-consistent integral equation theories and computer simulations are applied to the investigation of thermodynamic and structural properties as well as to the determination of the phase diagram of the hard-core Yukawa fluid. We consider different Yukawa-tail screening lengths λ, going up to λ=9, when the potential becomes so short-ranged that the interaction can be considered fairly similar to that present between macroparticles in colloidal suspensions and protein solutions. Theoretical approaches are found to give a reasonably accurate description of the physical properties of the system at high λ’s. The relative position of the sublimation vs. the liquid-vapor binodal line, known from computer simulations to play a crucial role in the onset of crystallization in protein solutions, seems qualitatively reproducible. We suggest on the basis of our results the possibility to extend such investigations to more realistic models of protein solutions, so to take into account the true multicomponent nature of these fluids, a physical situation whose description still challenges the currently available computer simulation capabilities. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2000

103. Generalized mean spherical approximation with internal thermodynamic consistency constraints: An application to hard sphere mixtures.

Author

Caccamo, C., Pellicane, G., and Ricciari, R.

Subjects
*THERMODYNAMICS, *PHASE diagrams
Abstract

We apply the Generalized Mean Spherical Approximation (GMSA) to hard sphere mixtures by imposing the thermodynamic consistency of the theory by means of both internal and external constraints. Structural results are obtained for a moderate to high size-asymmetry regime and compared with those we also obtain in the Rogers-Young theory, with previous Modified-Hypernetted Chain theory results and with Monte-Carlo simulation data. The overall good performances of the thermodynamically self-consistent GMSA and the semianaliticity of its solution scheme, thanks to which one could determine the phase diagram of the system in a fairly rapid manner, strongly suggest the opportunity to generalize our theoretical procedure to hard-core Yukawa mixtures, a model that is of relevance for the description of phase equilibria in globular protein solutions. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2000

104. Relaxation and phase transformations in simple atomic systems with short range interactions.

Author

Costa, D., Ballone, P., and Caccamo, C.

Subjects
ATOMIC structure, RELAXATION (Nuclear physics), PHASE transitions, MOLECULAR dynamics, CRYSTALLIZATION
Abstract

We simulate by molecular dynamics the long time evolution of metastable phases for particles interacting via a spherical, short range pair potential. We analyze the dynamics of the first order phase transitions taking place in the system, as well as the relaxation processes by which the system anneals the extended defects generated during the first stages of the phase transformations. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2000

117. A weak individual signature might not allow chick call recognition by parent Stone Curlews Burhinus oedicnemus.

Author

Dragonetti, M., Caccamo, C., Pollonara, E., Baldaccini, N. E., and Giunchi, D.

Subjects
*ANIMAL calls, *THICK-knees (Birds), *CHARADRIIFORMES, *RECOGNITION (Psychology), *SPECTROGRAPHS
Abstract

Offspring recognition has been confirmed in many bird species, and vocal signatures appear to be its major component. Up to now most studies dealt with colonial species, but recent findings indicate that similar recognition is also present in non-colonial birds. By integrating spectrographic analysis and playback experiments, we investigated for the first time parent--offspring vocal recognition in the Stone Curlew (Burhinus oedicnemus), a highly vocal, crepuscular-nocturnal species that usually rears a maximum of two precocial and nidifugous chicks. Even though the species is usually non-colonial and non-cooperative, in Taro River Regional Park, Parma, Italy, breeding territories are densely packed with distances between simultaneously active nests as close as 40 m, which creates the possibility that chicks might be exchanged. Our analysis identified two main vocalizations in the chick call repertoire: (1) the S-call, a brief strangled soft sound often uttered when parents and chicks were at close quarters; and (2) the C-call, a chirping sound with a complex structure, which seems to be a long-distance contact vocalization. Our acoustic analysis showed that, even though the structure was remarkably different between chicks, C-calls were an unreliable individual signature given their high intra-individual variability. This was confirmed by playback experiments. Indeed, when presented with simulated C-calling chicks, adults approached both their own and foreign chicks with equal responses. These results suggest that parent Stone Curlews are unable to recognize their offspring by voice. Furthermore, experiments are needed to test whether the chicks are able to recognize their parents' voice and, more generally, to understand the details of parent-offspring communication in this species. [ABSTRACT FROM AUTHOR]

Published
2013
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137. An Improved Closure of the Born-Green-Yvon Equation for the Electric Double Layer.

Author

PUERTO RICO UNIV RIO PIEDRAS DEPT OF PHYSICS, Caccamo,C, Pizzimenti,G, Blum,L, PUERTO RICO UNIV RIO PIEDRAS DEPT OF PHYSICS, Caccamo,C, Pizzimenti,G, and Blum,L

Abstract

An extensive series of calculations are made to compare an improved closure of the Born-Green-Yvon (BGY) equation for the electric double layer of primitive electrolytes to existing Monte Carlo simulation and other theories, such as the modified Poisson Boltzmann (version: 5) (MPB5) and the Hypernetted chain/mean spherical approximation (HNC,MSA), and its recent improvements. In contrast to these theories the BGY equation satisfies the contact theorem always. Furthermore the bulk pair correlations function used are the most accurate available, namely the HNC bulk results. The results show very good general agreement to the computer work for high densities and surface charges. In particular higher densities are obtained than those hitherto published in the literature. For low density 2-2 and 2-1 electrolytes the agreement is not as good for the other theories. Keywords: Primitive Model of Charged Interfaces Integral Equations.

Published
1985

140. Behavior of vascular endothelial growth factor and erythropoietin throughout the menstrual cycle in healthy women

Author

Caccamo C, Nostro L, Giorgianni G, Stefania Mondello, Crascì E, Frisina N, and Buemi M

Subjects
Adult, Vascular Endothelial Growth Factor A, blood, blood/pharmacology, blood/physiology, Humans, Female, blood/metabolism, Erythropoietin, Adult, Erythropoietin, blood/pharmacology, Female, Humans, Menstrual Cycle, blood/physiology, Menstruation, blood/metabolism, Recombinant Proteins, Vascular Endothelial Growth Factor A, Menstrual Cycle, Recombinant Proteins, Menstruation
Abstract

To evaluate any correlations between erythropoietin (EPO) and vascular endothelial growth factor (VEGF) levels in the serum and the menstrual fluid of healthy women during the different phases of the menstrual cycle.Blood samples from 25 healthy female volunteers were obtained for serum VEGF and EPO detection on the 1st, 7th, 14th, 21st and 25th days of the menstrual cycle. Menstrual fluid samples for VEGF and EPO detection were obtained on the 1st and 4th days of menstruation.Circulating VEGF levels were found to increase in a stage-dependent cyclic manner. The mean VEGF concentration in menstrual blood on the 1st day of the cycle was significantly higher than the mean plasma value and was reduced to a significant extent on the 4th day of the cycle. We found no significant changes in serum EPO levels. Mean EPO concentration detected in menstrual blood was comparable to those in serum blood either on the 1st or 4th day of the menstrual cycle.During menstruation, a local production of VEGF occurs independent of systemic production, thus sustaining angiogenic activity in autonomous, independent ways. Our findings demonstrate the presence of an "open compartment" that reflects the systemic pattern of EPO at the uterine level that allows us to speculate on different effects beyond the angiogenic action of EPO.

142. On the existence of a liquid phase of $C_6_0$

Author

Caccamo, C. and Caccamo, C.

Abstract

Recent theoretical and computer simulation results about the phase diagram of a model of rigid $C_6_0$ molecules are reported. A critical comparison is performed with recent investigation of the dependence of the liquid-vapor phase diagram topology on the characteristics of the interaction potential. Our evidence, correlated te the conclusions of such an overview, points to the existence of a rather small interval of temperatures and densities in which $C_6_0$ should be liquil.

143. Computer simulations of $C_6_0-Kr$ mixtures

Author

Abramo, M.C., Caccamo, C., Abramo, M.C., and Caccamo, C.

Abstract

Carbon $C_6_0$ fullerene mixed to $Kr$ rare gas at different concentrations and packing fractions has been simulated by microcanonical Molecular Dynamics (MD) in order to investigate the effect of the gas atoms on the structure and mobility of the $C_6_0$ molecules. A continnum representation for the $C_6_0$ molecule is assumed in order to use central model potentials for the three different interactions involved. A threshold value of the $Kr$ concentration is obtained for the $C_6_0$ spatial arrangement and mobility.

144. Microscopic theoretical calculation of critical exponents in classical fluid mixtures

Author

Caccamo, C. and Caccamo, C.

Abstract

We show in this paper that microscopic theoretical approaches can be applied with confidence for the determination of phase stability conditions both of model and real multicomponent classical fluid mixtures. We examine the performances of two theories, namely the Mean Spherical Approximation (MSA) and the Hypernetted Chain (HNC) approximation by comparing their results with those of computer simulation and with the available experimental evidence. The two theories agree qualitatively with each other; moreover the MSA, though inconsistent as a theory from the thermodynamic point of view, is capable to predict in a very direct, and rapid manner the essential qualitative features of the phase diagrams of both neutral and charged fluids. Calculations for the critical exponents are reported in such a context, by showing that the MSA approach allows an accurate determination of these quantities and that the result obtained are consistent with the previous literature.

145. On the existence of a liquid phase of $C_6_0$

Author

Caccamo, C. and Caccamo, C.

Abstract

Recent theoretical and computer simulation results about the phase diagram of a model of rigid $C_6_0$ molecules are reported. A critical comparison is performed with recent investigation of the dependence of the liquid-vapor phase diagram topology on the characteristics of the interaction potential. Our evidence, correlated te the conclusions of such an overview, points to the existence of a rather small interval of temperatures and densities in which $C_6_0$ should be liquil.

146. Computer simulations of $C_6_0-Kr$ mixtures

Author

Abramo, M.C., Caccamo, C., Abramo, M.C., and Caccamo, C.

Abstract

Carbon $C_6_0$ fullerene mixed to $Kr$ rare gas at different concentrations and packing fractions has been simulated by microcanonical Molecular Dynamics (MD) in order to investigate the effect of the gas atoms on the structure and mobility of the $C_6_0$ molecules. A continnum representation for the $C_6_0$ molecule is assumed in order to use central model potentials for the three different interactions involved. A threshold value of the $Kr$ concentration is obtained for the $C_6_0$ spatial arrangement and mobility.

147. Microscopic theoretical calculation of critical exponents in classical fluid mixtures

Author

Caccamo, C. and Caccamo, C.

Abstract

We show in this paper that microscopic theoretical approaches can be applied with confidence for the determination of phase stability conditions both of model and real multicomponent classical fluid mixtures. We examine the performances of two theories, namely the Mean Spherical Approximation (MSA) and the Hypernetted Chain (HNC) approximation by comparing their results with those of computer simulation and with the available experimental evidence. The two theories agree qualitatively with each other; moreover the MSA, though inconsistent as a theory from the thermodynamic point of view, is capable to predict in a very direct, and rapid manner the essential qualitative features of the phase diagrams of both neutral and charged fluids. Calculations for the critical exponents are reported in such a context, by showing that the MSA approach allows an accurate determination of these quantities and that the result obtained are consistent with the previous literature.

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