Study of relaxor-like behaviour of laser ablated (Pb, La)Tio3 thin films

Lanthanum modified lead titanate (PLT) thin films are one of the potential candidates for the pyroelectric and memory applications due to their excellent dielectric, pyroelectric and ferroelectric properties. PLT thin films with 25 at.% of La were deposited on platinum coated Si substrates by the laser ablation technique. The phase transition studies were done in the temperature range of −40 to 150 °C as a function of frequency and ac field. A diffused phase transition with the shifting of the maximum dielectric permittivity (?_max) to higher temperatures with the increase of frequency and dielectric dispersion with frequency at the lower temperatures were observed. The variation of the temperature corresponding to maximum dielectric constant T_m, with frequency follows the Vogel-Fulcher relation, which is the characteristic of the relaxor-like behavior of the material. With the increase of ac drive, the T_max was shifted to lower value.     

Rotationally Invariant Proof of Bell’s Theorem Without Inequalities for 4k-Dimensional (k=1,2,...) Systems

We present rotationally invariant proof of Bell‘s theorem without inequalities for spin-(2N 1)/2system (N = 2k-1,k = 1, 2, 3, 4...) with only two particles, which is a generalization of Cabello‘s study [Phys. Rev. A 67 (2003)032107].     

Comparison of the non-uniform chiral and 2SC phases at finite temperatures and densities

We study the phase diagram of the strongly interacting matter at finite temperatures and densities including 2SC, uniform chiral and non-uniform chiral phases within the Nambu–Jona-Lasinio model in the mean field approximation.     

A four-level “Ξ-system”: Exact solvability and effective evolution operators via multiple scales

Properties of a four-level atomic system interacting with one and two modes of the electromagneticfield in a “Ξ”-configuration are investigated. By linearization of the Hamiltonians we show that the corresponding mathematical models are exactly solvable. To obtain simpler effective Hamiltonians the perturbative method of multiple scales is applied. The lowest-order corrections to the resulting effective evolution operators are also calculated.     

Interactions of xanthines with activated carbon: II. The adsorption equilibrium

In the present work, we have studied the adsorption of xanthine derivatives by activated carbon sorbents in aqueous solutions. The study comprised both kinetic, equilibrium and thermodynamic aspects. The kinetic results were reported in a previous paper; the equilibrium-related results are discussed here. The two types of carbon used exhibit some differences but the equilibrium isotherms obtained are all of the H-3 type in the classification of Giles. This suggests a high affinity of the sorbents for the sorbates. We also found that the overall adsorption process comprises more than one individual adsorption-desorption process of which one leads to the formation of a “monolayer” and the other to the “precipitation” of the sorbate on the sorbent surface (multilayer adsorption); the amount of sorbate adsorbed in monolayer form was seemingly greater in C-A14.     

Doppler-broadening measurements of microvoids at the Au/GaAs interface

Recent positron lifetime studies made on the Au/GaAs interface with an applied electric field returning a significant fraction of bulk implanted positrons to the interface have revealed the presence of microvoids( 1 nm diameter) at the interface. In this work an attempt has been made to study these microvoids by observing the Doppler broadening on the annihilation radiation coming from them. This is done both by observing theS-parameter as a function of applied bias and by applying the generalized least-squares method to the deconvolution of the annihilation radiation lineshape. The general conclusion is that the Doppler-broadened data are consistent with the majority of positrons trapping into microvoids, probably associated with grain boundaries. The data suggest that these open volume defects are more associated with the Au film rather than the Au-Ga alloyed interfacial region.Paper presented at the 132nd WE-Heraeus-Seminar on Positron Studies of Semiconductor Defects, Halle, Germany, 29 August to 2 September 1994     

Qubit disentanglement in local squeezed reservoirs

We consider the influence of the local squeezed vacuum fields on two initially entangled two-qubit system. By considering the upper bound of entanglement under time evolution, we find that the decay of the quantum entanglement shows different behavior for different time scales (t?max{(2βA)⁻¹,(2βB)⁻¹}$t?\max \{{(2{\beta }_A)}^{\mathrm{-1}},{(2{\beta }_B)}^{\mathrm{-1}}\}$ and t?min{(2βA)⁻¹,(2βB)⁻¹}$t?\min \{{(2{\beta }_A)}^{\mathrm{-1}},{(2{\beta }_B)}^{\mathrm{-1}}\}$). The relative phase of the squeezing environment can also affect the entanglement dynamics profoundly.     

Hes1调控 AKT-MDM2-p53-PTEN通路的一种物理机制

基于Hill动力学与Michaelis-Menten方程,建立理论模型研究发状分裂相关增强子1(hairy and enhancer of split 1,Hes1)调控蛋白激酶B (Protein Kinase B,AKT)-鼠双微体2 (Murine Double Minute2,MDM2)-抗癌基因p53(p53)-第10号染色体缺失的磷酸酶及张力蛋白同源的基因(Phosphatase and tensin homolog deleted on chromosome ten,PTEN)通路的一种物理机制.研究发现,Hes1通过与PTEN结合抑制PTEN表达,并调控AKT信号.表明了Hes1蛋白的合成,以及Hes1与PTEN相互作用调控AKTMDM2-p53-PTEN通路信号,将会有效地控制细胞结果 . Hes1作为AKT-MDM2-p53-PTEN信号通路中上游调节的重要因素,还可以在一定程度上通过影响p53蛋白功能,改变p53对肿瘤的抑制性.理论结果可用于预测Notch通路信号异常诱导的致癌性,并进一步揭示了Notch信号通路影响细胞AKT-MDM2-p53-PTEN通路的激活...     

Analysis of a recent experiment seemingly favouring local realism against quantum mechanics

A recent experiment by Brida et al. [Eur. Phys. J. D 44, 547 (2007)] is analyzed with the conclusion that the results disagree with standard quantum predictions but fit a simple local hidden variables model. New experiments are proposed which might throw new light on the anomaly.     

Monte Carlo simulations of star-branched polyelectrolyte micelles

The concentration profiles of monomers and counterions in star-branched polyelectrolyte micelles are calculated through Monte Carlo simulations, using the freely jointed chain model. We have investigated the onset of different regimes corresponding to the spherical and Manning condensation of counterions as a function of the strength of the Coulomb coupling. The Monte Carlo results are in fair agreement with the predictions of Self-Consistent-Field analytical models. We have simulated a real system of diblock copolymer micelles of (sodium-polystyrene-sulfonate)(NaPSS)-(polyethylene-propylene)(PEP) with f = 54 hydrophilic branches of N = 251 monomers at room temperature in salt-free solution. The calculated form factor compares nicely with our neutron scattering data. Received 18 July 2002 and Received in final form 11 October 2002 RID="a" ID="a"e-mail: roger@drecam.saclay.cea.fr