On a new class of nonlinear wave equations

In this paper we prove the existence and uniqueness of regular solutions for the Cauchy problem for the evolution equation $\text{u″ + A}{}^2\text{u + (α + M(¦A}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{u¦}{}^2\text{) Au = 0}$, suggested by the study of beams and plates. We represent by A a linear operator of a Hilbert space H with norm ∥, α is a real number, and M(λ) > 0 a real function, for λ ? 0.     

Proton radioactivity: The case for <Superscript>53m</Superscript>Co proton-emitter isomer

The partial proton emission half-life for ^53mCo unstable isomer is re-examined in the framework of a semiempirical model based on tunneling through a Coulomb-plus-centrifugal-plus-overlapping potential barrier within the spherical nucleus approximation. It is shown that the known measured half-life value of 17s is compatible with a large prolate shape for ^53mCo proton emitter and a high angular momentum ℓ = 11 assigned to the proton transition to the ground state of ⁵²Fe .     

Dispersion Robustness of Millimeter Waves Generated by Up-Conversion Strategies

Abstract

The performance degradation caused by transmission along dispersive single-mode fibers of optically generated millimeter-wave signals using up-conversion is theoretically assessed and validated by numerical simulation. Up-conversion techniques based on optical double sideband, optical single sideband, and optical carrier suppression are considered. The generation of 60 GHz by frequency tripling using the optical single sideband is shown to be particularly tolerant to the fiber dispersion. The practical imbalance of Mach-Zehnder modulators is taken into account for optical carrier suppression modulation, where the finite extinction ratio is found to increase tolerance to fiber dispersion.     

Relative Intensity Noise in Optical Single Side Band Systems with Multiple In-Line Amplifiers: Analysis and Validation

Abstract

This article analyzes and validates through simulation the influence of fiber nonlinearity, dispersion, and loss on the Relative Noise Intensity (RIN) spectrum at fiber output in externally modulated optical single side band (OSSB) systems. The analysis includes the RIN generated by the laser source, the effect of the OSSB modulator, and noise generated by the in-line optical amplifiers. The analysis takes into account conversion between phase noise and intensity noise introduced by fiber transmission. It is shown that, depending on the operating conditions, the system performance may be predominantly affected either by the laser RIN or by the noise generated by the in-line optical amplifiers. The impact of the OSSB modulator can be relevant when the RIN of the system is dominated by the laser noise and should therefore be considered.     

Vortex condensation in the dual Chern–Simons–Higgs model

The contribution of nontrivial vacuum (topological) excitations, more specifically vortex configurations of the self-dual Chern–Simons–Higgs model, to the functional partition function is considered. By using a duality transformation, we arrive at a representation of the partition function in terms of which explicit vortex degrees of freedom are coupled to a dual gauge field. By matching the obtained action to a field theory for the vortices, the physical properties of the model in the presence of vortex excitations are then studied. In terms of this field theory for vortices in the self-dual Chern–Simons–Higgs model, we determine the location of the critical value for the Chern–Simons parameter below which vortex condensation can happen in the system. The effects of self-energy quantum corrections to the vortex field are also considered.     

Self-assembled films of cellulose nanofibrils and poly(<Emphasis Type="Italic">o</Emphasis>-ethoxyaniline)

Nanostructured films of poly(o-ethoxyaniline) (POEA) alternated with cellulose nanofibrils (CnF) were successfully produced by self assembly (SA) at different pH values and investigated by atomic force microscopy and ultraviolet-visible spectroscopy. Results show that it was possible to build up films by alternating POEA and CnF layers with relatively precise architectural control by controlling the number of layers and pH. Film thickness had a dependence on pH which is a combination of the effects of the deposited amount for each POEA layer and the pH at which the absorption of the cellulose nanofibrils was carried out. Comparison of alternated layers of POEA and CnF with multi-immersions of POEA at different pH values, as measured by the ratio between slopes of the straight lines of deposited amount of polymer versus the number of self-assembled layers, shows that alternate deposition at pH 2 has a fourfold increase in the slope. Alternatively, at pH 5, there is no significant difference whether the deposition is alternated (POEA–CnF) or not (POEA).     

Continuous monitoring of ascorbate transport through neuroblastoma cells with a ruthenium oxide hexacyanoferrate modified microelectrode

The uptake of ascorbate by neuroblastoma cells using a ruthenium oxide hexacyanoferrate (RuOHCF)-modified carbon fiber disc (CFD) microelectrode (r = 14.5 microm) was investigated. By use of the proposed electrochemical sensor the amperometric determination of ascorbate was performed at 0.0 V in minimum essential medium (MEM, pH = 7.2) with a limit of detection of 25 micromol L(-1). Under the optimum experimental conditions, no interference from MEM constituents and reduced glutathione (used to prevent the oxidation of ascorbate during the experiments) was noticed. The stability of the RuOHCF-modified electrode response was studied by measuring the sensitivity over an extended period of time (120 h), a decrease of around 10% being noticed at the end of the experiment. The rate of ascorbate uptake by control human neuroblastoma SH-SY5Y cells, and cells transfected with wild-type Cu,Zn-superoxide dismutase (SOD WT) or with a mutant typical of familial amyotrophic lateral sclerosis (SOD G93A), was in agreement with the level of oxidative stress in these cells. The usefulness of the RuOHCF-modified microelectrode for in vivo monitoring of ascorbate inside neuroblastoma cells was also demonstrated.     

Thermodynamic response functions of fluids: a microscopic approach based on NpT Monte Carlo

On the basis of NpT Monte Carlo simulations, a detailed analysis on the microscopic origins of some specific features of thermodynamic response functions of fluids is performed. Specifically, the residual isobaric heat capacity C(p) (res), the isobaric thermal expansivity alpha(p), and the isothermal compressibility kappa(T) for Lennard-Jones methane and optimized potential for liquid simulations (OPLS) methanol have been determined via standard techniques. For the former, data along the liquid, gas, and supercritical regions are presented, while a wide temperature range at a single supercritical pressure is covered for the latter. They have been obtained by computing the various pairwise fluctuations contributing to each property. Attention is mainly focused on isothermal and isobaric maxima found for both C(p) (res) and alpha(p), which have been rationalized at a molecular level using qualitative arguments. It is encountered that maxima emerge as a natural consequence of the destruction of fluid structure as temperature is increased or as pressure is decreased. The results for Lennard-Jones methane reveal the competition of energetic and volumetric effects, while those for OPLS methanol evidence that hydrogen-bonding is dominant as energetic effects are concerned. Further discussion on previous results and alternative approaches using equations of state as well as on closely related topics such as "maxima and critical phenomena" is included.