Making use of the poroelastic theory for hydrated polymeric matrices, the ultrasound (US) propagation in a gel medium filled by spherical cells is studied . The model describes the connection between the poroelastic structure of living means and the propagation behavior of the acoustic waves. The equation of fast compressional wave, its phase velocity and its attenuation as a function of the elasticity, porosity and concentration of the cells into the gel external matrix are investigated. The outcomes of the theory agree with the measurements done on PVA gel scaffolds inseminated by porcine liver cells at various concentrations. The model is promising in the quantitative non-invasive estimation of parameters that could asses the change in the tissue structure, composition and architecture.
In this work an extremal principle driving the far from equilibrium evolution of a system of structureless particles is derived by using the stochastic quantum hydrodynamic analogy. For a classical phase (i.e., the quantum correlations decay on a distance smaller than the mean inter-molecular distance) the far from equilibrium kinetic equation can be cast in the form of a Fokker-Plank equation whose phase space velocity vector maximizes the dissipation of the energy-type function, named here, stochastic free energy. Near equilibrium the maximum stochastic free energy dissipation is shown to be compatible with the Prigogine s principle of minimum entropy production. Moreover, in the case of elastic molecular collisions and in absence of chemical reactions, in quasi-isothermal far from equilibrium states, the theory shows that the maximum stochastic free energy dissipation reduces to the maximum free energy dissipation. Following the tendency to reach the highest rate of stochastic free energy dissipation, the system transition to states with higher free energy can happen. Given that in incompressible ordinary fluids such an increase of free energy is almost given by a decrease of entropy, the matter self-organization becomes possible. When chemical reactions or relevant thermal gradients are present, the theory highlights that the Sawada enunciation of maximum free energy dissipation can be violated. The proposed model depicts the Prigogine s principle of minimum entropy production near-equilibrium and the far from equilibrium Sawada s principle of maximum energy dissipation as two complementary principia of a unique theory where the latter one is a particular case of the more general one of maximum stochastic free energy dissipation.
The quantum hydrodynamic-like equations as a function of two real sets of variables (i.e., the 4x4 action matrix and the 4-dimensional wave function modulus vector) of the Dirac equation are derived in the present work. The paper shows that in the low velocity limit the equations lead to the hydrodynamic representation of the Pauli’s equation for charged particle with spin given by Janossy [1] and by Bialynicki et al [2]. The Lorentz invariance of the relativistic quantum potential that generates the non-local behavior of the quantum mechanics is discussed.
Summary If delivered at elevated intensity, ultrasound potentiates enzymatic clot dissolution; however, an elevated acoustic intensity damages vascular wall and favors reocclusion. This study’s aim was to investigate whether exposure to high-frequency, lowintensity ultrasound generated by a diagnostic scanner enhances enzymatic thrombolysis, and if this effect differs in clots from blood of normal subjects and of patients with coronary artery disease (CAD). Venous blood samples were drawn from 10 healthy volunteers and from 10 CAD patients on chronic medical treatment, which also included aspirin. Each sample generated 2 radiolabelled clots, which were positioned in 2 in vitro models filled with human plasma recirculating at 37°. One clot was exposed to acetyl salicylic acid (60 μg/ml), tissue plasminogen activator (3 μg/ml) and heparin (1 IU/ml), while the other was exposed to the same medications plus ultrasound (2.5 MHz, mechanical index = 1.0) for 3 hours. Enzymatic thrombolysis was measured as solubilization of radiolabel. Normal subjects and patients did not significantly differ as to coagulation parameters, weight, volume and density of the clots, and fibrinolytic activity (p = 0.794). Ultrasound exposure did not influence thrombolysis in clots of normal subjects (p = 0.367), while it enhanced the dissolution of clots of CAD patients (p = 0.013). The enhancement was equal to 51% at 5 minutes, 32% at 15 minutes, 27% at 30 minutes, 20% at 1 hour and 19% at 3 hours (p < 0.05). Diagnostic ultrasound enhances enzymatic dissolution of clots generated from the blood of CAD patients, likely due to chronic treatment and in particular to aspirin.
The connection between the micro and macro-arrow of time is discussed in the frame of the stochastic quantum hydrodynamic analogy. The presence of fluctuations that in the case on non-linear interactions leads to the breaking of the quantum mechanics on large scale and then to the macroscopic irreversibility and arrow of time, gives also rise to the time reversal breaking in the micro-scale quantum stochastic evolution (micro-arrow of time). The quantum irreversibility and the theoretical tools to calculate the time reversal asymmetry in the elementary particle decays are briefly discussed.
