Relationships between otolith major axis length (mm) and fish size (total length, cm) were described by means of linear regression analysis for six demersal fish species from the NW Mediterranean: blue whiting (Micromesistius poutassou), greater forkbeard (Phycis blennoides), red mullet (Mullus barbatus), poor cod (Trisopetus minutus capelanus), horse mackerel (Trachurus trachurus), and Mediterranean mackerel (Trachurus mediterraneus). Results show that reconstruction of body size from otolith measurement is possible by applying this approach based on the relationship of otolith length - fish length.

In the present paper, we extend the method described in paper I [D. Bertolini and A. Tani, preceding paper, Phys. Rev. E 83, 031201 (2011)] to molecular liquids, which allows us to solve the exact kinetic equation proposed by de Schepper et al. [Phys. Rev. A 38, 271 (1988)] without approximations. In particular, generalized thermodynamic properties (enthalpy, specific heat, and thermal expansion coefficient) and transport properties (longitudinal viscosity, thermal conductivity) have been calculated for three liquids of increasing complexity, namely dimethyl sulfoxide, hydrogen fluoride, and SPC/E water. All results have been obtained by the molecular formalism as well as the atomic one, corrected for intramolecular correlations that are due to the models adopted. As done for simple liquids, the coupling between the viscous stress tensor and the energy flux vector has been calculated exactly. We also show that the Markov assumption for the dynamics related to thermal conductivity can only be adopted with caution.

We propose a method by which the generalized transport properties and coefficients at all wavelengths and frequencies can be obtained by inversion of an exact kinetic equation. The necessary data are the density-density, energy-energy, and density-energy time correlation functions, which can be obtained by molecular-dynamics simulation. In addition, also the coupling between viscous stress tensor and energy flux vector can be obtained without approximation. This allows one to check the validity of the Markov assumption in a straightforward way. As a first test case, the theory is applied to liquid argon in two thermodynamic states. For this system, we calculate and discuss generalized thermodynamic (enthalpy, specific heats, and thermal expansion) and transport properties (longitudinal viscosity, thermal conductivity).

Recent neutron scattering results [F. Demmel et al., Phys. Rev. B 73, 104207 (2006)] on the temperature dependence of de Gennes narrowing in liquid rubidium have stimulated a molecular dynamics (MD) study in the same temperature and density range. At the $k$ value of the first peak of $S(k)$, the MD results agree very well with experimental data of $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{S}({k}_{\mathrm{max}},\ensuremath{\omega}=0)$, $F({k}_{\mathrm{max}},t=0)$, and longitudinal viscosity ${\ensuremath{\eta}}_{L}({k}_{\mathrm{max}},\ensuremath{\omega}=0)$. Other transport properties, such as self-diffusion and shear viscosity, are also accurately reproduced. At $k=0$, on the other hand, the MD results significantly underestimate the experimental values of bulk viscosity and thermal conductivity. For the latter, this is a well known deficiency of models which do not explicitly take into account the electronic contribution to thermal exchanges. However, the large difference between MD and macroscopic experimental data for bulk viscosity casts some doubts on its indirect calculation from sound absorption data. This contradictory result, which presumably extends to all alkali metals, is discussed in the light of various theoretical models.

We report a molecular dynamics simulation study on the isotropic phase of an idealized calamitic liquid crystal model with a length-to-width ratio of approximately 5-6. The study focuses on the characterization of single-particle and collective orientational dynamics on approaching the phase transition to the nematic phase. Recent experimental and simulation works have suggested that a power law behavior exists at relatively short times in the decay of the time derivative of the orientational correlation functions. Qualitatively, our simulation data are consistent with these findings. Both single-particle and collective time correlation function derivatives possess, in their respective log-log plots, a linear region at very short times, whose slope is essentially independent from the thermodynamic state. Nevertheless, the single-particle orientational correlation functions are better described by a function which is the sum of a fast exponential, an intermediate stretched-exponential and a slow exponential, while the collective orientational correlation functions are satisfactorily described by a sum of two exponentials, at higher density, or by just one exponential, at lower density.

The phenomenon of the micromechanically detected magnetic resonance is interpreted in terms of nonlinear processes at magnetic resonance. A close analysis in the frequency domain of the irradiation and detection scheme shows that the technique corresponds to a multiple irradiation with one or more couple of frequencies separated by omega(c) and to the detection of the longitudinal component of magnetization oscillating at omega(c). The study of longitudinal detection of magnetic resonance allows the direct measurement of the spin-lattice relaxation time of samples. Samples of Mn2+:MgO prepared in order to obtain a mixture of spin systems with very different relaxation processes were studied by electron-spin-resonance experiments with micromechanical detection: measurements evidence a very strong rejection of the system with lower longitudinal relaxation time. Direct confirmation of the theoretical interpretation is obtained; in addition the microscopy technique increases its "contrast" capability, adding the possibility of determining maps of samples based on the distribution of both concentration and longitudinal relaxation times of spin systems.

We have calculated generalized longitudinal, ηL(k), shear, ηS(k), and bulk, ηB(k) viscosity of argon at two thermodynamic states by molecular-dynamics simulation. Bulk viscosity has been evaluated with two independent methods that give results in good agreement. We find that bulk viscosity stays positive at all wave numbers k, and show that negative values of ηB(k) are due to a straightforward (and incorrect) extension to finite k’s of the relation ηB(k)=ηL(k)−4ηS(k)/3, only valid at vanishing k’s.

The dynamical properties of liquid hydrogen fluoride are investigated by a molecular dynamics study of the correlation functions relevant for a generalized hydrodynamics description of transport coefficients. The results are compared with the corresponding ones in liquid water in order to understand the role of hydrogen bonding in the two systems. The different behavior can ultimately be attributed to the arrangement of the molecules, which form irregular chains in HF and a tetrahedral network in water. For the two systems, the differences between experimentally measurable quantities are also pointed out and discussed.

The center-of-mass velocity autocorrelation function is analyzed by computer simulation in a model of liquid hydrogen fluoride at two state points. In comparison with water (another hydrogen-bonded liquid) new features arise. To understand the peculiarities of HF, we have investigated atomic velocity correlations in both the laboratory and a molecular frame. The comparison of the frequency spectra permits to ascertain the role of fluorine–hydrogen correlations (or of rototranslational couplings) in the center-of-mass velocity autocorrelation function. At low temperature, the appearance of a long time tail is discussed in terms of projections in the two references frames, and found to be mostly associated with orientational correlations. A discussion in terms of velocity transfer between nearest-neighbor molecules is also given.

The development of a spectrometer for simultaneous mechanical and electromagnetic detection of electron paramagnetic resonance working at 23 GHz and under vacuum is described. Experiments realized on different samples show the performances of the apparatus. Possible perspectives are presented.

The peculiar advantages of simultaneous observation by electromagnetic and micromechanical methods in EPR spectroscopy are discussed. The development of a novel apparatus with the capability of this simultaneous detection is described. Experiments at 23 GHz show the performance of the apparatus. The problems related to the sensitivity and to the spatial resolution are analyzed. Future prospects are presented. Copyright 1999 Academic Press.

The role of hydrogen bonding in the determination of the dynamical properties of liquids is investigated by a computer simulation of HF, and compared with water. Sound dispersion is found to be much smaller and interpretable in terms of the viscoelastic approximation. Some dynamical solidlike features are found even in this liquid and interpreted in terms of localized motions of molecules along topological chains present in the liquid. The present investigation answers some relevant questions concerning the dynamical behavior of associated liquids.

In this paper we present a statistical model to describe the dielectric behavior of binary solutions. The formal development is based on the introduction of a few dynamical parameters describing the interactions occurring in the solution; these parameters enter in the rate equations for the dynamics of mixing. These equations, after suitable linearization, are used as the starting point to obtain the dipole correlation functions necessary to study the dielectric relaxation processes. The model is able to indicate the conditions which a mixture composed of two liquids with very different relaxation times must fulfill to produce a single relaxation time, as often experimentally observed. Some significant results reported in the literature are analyzed and explained and new experimental data are reported in order to test specific features of the model. All tests carried out so far on binary solutions give a successful reproduction of experimental results.

Equilibrium molecular dynamics simulations have been carried out in the microcanonical ensemble at 300 and 255 K on the extended simple point charge (SPC/E) model of water [Berendsen et al., J. Phys. Chem. 91, 6269 (1987)]. In addition to a number of static and dynamic properties, thermal conductivity lambda has been calculated via Green-Kubo integration of the heat current time correlation functions (CF's) in the atomic and molecular formalism, at wave number k=0. The calculated values (0.67 +/- 0.04 W/mK at 300 K and 0.52 +/- 0.03 W/mK at 255 K) are in good agreement with the experimental data (0.61 W/mK at 300 K and 0.49 W/mK at 255 K). A negative long-time tail of the heat current CF, more apparent at 255 K, is responsible for the anomalous decrease of lambda with temperature. An analysis of the dynamical modes contributing to lambda has shown that its value is due to two low-frequency exponential-like modes, a faster collisional mode, with positive contribution, and a slower one, which determines the negative long-time tail. A comparison of the molecular and atomic spectra of the heat current CF has suggested that higher-frequency modes should not contribute to lambda in this temperature range. Generalized thermal diffusivity D-T(k) decreases as a function of k, after an initial minor increase at k = k(min). The k dependence of the generalized thermodynamic properties has been calculated in the atomic and molecular formalisms. The observed differences have been traced back to intramolecular or intermolecular rotational effects and related to the partial structure functions. Finally, from the results we calculated it appears that the SPC/E model gives results in better agreement with experimental data than the transferable intermolecular potential with four points TIP4P water model [Jorgensen et al., J. Chem. Phys. 79, 926 (1983)], with a larger improvement for, e.g., diffusion, viscosities, and dielectric properties and a smaller one for thermal conductivity. The SPC/E model shares, to a smaller extent, the insufficient slowing down of dynamics at low temperature already found for the TIP4P water model.

The time correlation functions (CF's) of diagonal and off-diagonal components of the stress tenser of water have been calculated at 245 and 298 K in a molecular dynamics (MD) study on 343 molecules in the microcanonical ensemble. We present results obtained at wave number k = 0 and at a few finite. values of k, in the atomic and molecular formalism. In all cases; more than 98% of these functions are due to the potential term of the stress tenser. At k = 0, their main features are a fast oscillatory initial decay, followed by a long-time tail more apparent in the supercooled region. Bulk and shear viscosities, calculated via Green-Kubo integration of the relevant CF at k = 0, are underestimated with respect to experimental data, mainly at low temperature, but their ratio (approximate to 2)is correctly reproduced. Both shear and bulk viscosity decrease as a function of k, the latter more rapidly, so that they become almost equal at approximate to 1 Angstrom(-1) Also, both viscosities drop rapidly from their maximum at omega = 0. This behavior has been related to the large narrowing observed in the acoustic band, mainly in the supercooled region. The infinite frequency bulk and shear rigidity moduli have been shown to be in fair agreement with the experimental data, provided the MD value used for comparison is that corresponding to the frequency range relevant to ultrasonic measurements. The MD results of stress-stress CF's compare well with those predicted by Bertolini and Tani [Phys. Rev. E 51, 1091 (1995)] at k = 0, by an application of generalized hydrodynamics [de Schepper et al., Phys. Rev. A 38, 271 1988)] in the molecular formalism, to the same model of water (TIP4P) [Jorgensen et al., J. Chem. Phys. 79, 926 (1983)]. These CF's are essentially equal in the: atomic and molecular formalism, the only minor difference being restricted to the high frequency librational region of the shear function. By a comparison of atomic and molecular results, we show here that neglecting libration has no effect on the density-density and longitudinal current CF's and very little effect on transverse properties. On the other hand, this study points out the importance of including the oscillation in the nearest-neighbor cage in the memory function of the longitudinal and transverse current CF. The oscillatory local motion turns out to play an important role in all CF's and hence contributes significantly to the value of viscosity and of rigidity moduli.

We discuss an application of extended hydrodynamics to a model of water, in a range of wave numbers k, where the effect of single-molecule modes must be taken into account together with the collective phenomena underlying sound propagation and dispersion. The calculation of the density-density, energy-density, energy-energy, and longitudinal and transverse current correlation functions from a molecular dynamics simulation of the transferable intermolecular potential with four points (TIP4P) model of water, allows us to obtain the k dependence of the generalized hydrodynamic coefficients. In particular, we have found that the ratio of generalized heat capacities \ensuremath{\gamma}(k)=${\mathit{c}}_{\mathit{p}}$(k)/${\mathit{c}}_{\mathit{v}}$(k)\ensuremath{\simeq}1 up to k\ensuremath{\simeq}1 \AA{} $^{\mathrm{\ensuremath{-}}1}$ and that the correlation between temperature and density fluctuations is negligible at all times, while there is an important frequency dependence of the transport coefficients. This leads to a remarkable simplification of the expression of the Laplace transform of the correlation functions, although models for the transport coefficients are still necessary at the present state of the theory. The frequency dependence of the transport coefficients is necessary to describe correctly the behavior of the density-density and temperature-temperature autocorrelation functions (ACF's).A model for the frequency dependence of the generalized viscosity \ensuremath{\varphi}\ifmmode \tilde{}\else \~{}\fi{}(k,z) and thermal diffusivity D${\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}_{\mathit{T}}$(k,z) is proposed here. In addition to the correct short-time behavior of the correlation functions of the memory kernel, this model is able to account satisfactorily for the effects of the acoustic mode and the single-molecule modes, in particular, that related to the oscillation in the nearest neighbor cage (45 THz). A simple polynomial extrapolation to k=0 of the parameters of the model gives values consistent with the large sound dispersion observed in water. In the supercooled region, the shape of the predicted dispersion curve shows that there are two k ranges, 0.01--0.03 and 0.2--0.5 \AA{} $^{\mathrm{\ensuremath{-}}1}$, which account for most of the dispersion. When the temperature increases the contribution to the lower k range is less apparent and shifted to higher k, but the behavior of the 0.2--0.5 \AA{} $^{\mathrm{\ensuremath{-}}1}$ range does not change. The model also predicts an acoustic mode frequency ${\mathrm{\ensuremath{\omega}}}_{\mathrm{max}}$(k)/k, 2--3 times larger, and a bandwidth \ensuremath{\Delta}${\mathrm{\ensuremath{\omega}}}_{1/2}$(k)/${\mathit{k}}^{2}$, almost an order of magnitude smaller than those in the hydrodynamic regime. Moreover, ${\mathrm{\ensuremath{\omega}}}_{\mathrm{max}}$(k) and \ensuremath{\Delta}${\mathrm{\ensuremath{\omega}}}_{1/2}$(k) are in quantitative agreement with the neutron scattering data at T=298 K.The location and height of the first step of the dispersion curve are related to the long-time tail of generalized viscosity, while its size is determined by the anomalous value of the second moment of the longitudinal current ${\mathrm{\ensuremath{\omega}}}_{\mathrm{\ensuremath{\infty}}}$(k) as compared to that of the density-density ACF ${\mathrm{\ensuremath{\omega}}}_{0}$(k). The analysis of the transverse current ACF with the same model and the value of the transport coefficients obtained confirm that the TIP4P model potential leads to a shear and bulk viscosity in satisfactory agreement with the experimental data at 298 K. In the supercooled region, conversely, the dynamics obtained with the TIP4P potential is 2--3 times faster than that of real water at the same temperature, as already noted for the self-diffusion coefficient and dielectric relaxation times.

We report here the first observation of the time-dependent heat capacity of water-lysozyme solution. The observed increase of heat capacity in time occurs independently of the lysozyme concentration and thepH value of the solvent. The time necessary to attain the heat capacity equilibrium value and the amplitude of the effect are not well reproducible; the former tends to increase with temperature, while the amplitude decreases and practically disappears about 35°C. Evolution of a spatial order of the proteins in water and/or of water molecules interacting with the proteins is considered as a possible explanation for the results. The phenomenon promises to be an important tool to study the role of water in biological organization and activity.