A stochastic delay financial model

We compute the logarithmic utility of an insider when the financial market is modelled by a stochastic delay equation. Although the market does not allow free lunches and is complete, the insider can draw more from his wealth than the regular trader. We also offer an alternative to the anticipating delayed Black-Scholes formula, by proving stability of European call option prices when the delay coefficients approach the nondelayed ones.

     

pH buffer assessment and Pitzer��s equations

Traceable measurement of the quantity pH in media outside the limits of the recent IUPAC recommendation requires an alternative to the Bates?CGuggenheim convention. The Pitzer??s approach to ion interactions is widely appraised and offers a suitable approach to the estimation of single-ion activity coefficients. For this purpose, the underlying electrolyte data need to be consistent and the uncertainty in existing Pitzer??s data needs to be assessed. Such an assessment is attempted in this study for pH in potassium acetate buffer medium. The re-evaluation of Pitzer??s data from potassium nitrate data revealed inconsistencies and wide uncertainty margins. The uncertainty contribution from binary Pitzer??s parameters to an assessment of pH in seawater resulted in an uncertainty in pH of about 0.03 (95% confidence interval). This contribution has to be taken into account in the overall uncertainty budget. Lack of appropriate data for other pH buffer systems (e.g., phosphate buffers) is noted.     

Metric dimensional reduction at singularities with implications to Quantum Gravity

A series of old and recent theoretical observations suggests that the quantization of gravity would be feasible, and some problems of Quantum Field Theory would go away if, somehow, the spacetime would undergo a dimensional reduction at high energy scales. But an identification of the deep mechanism causing this dimensional reduction would still be desirable. The main contribution of this article is to show that dimensional reduction effects are due to General Relativity at singularities, and do not need to be postulated ad-hoc.     

Einstein equation at singularities

Einstein’s equation is rewritten in an equivalent form, which remains valid at the singularities in some major cases. These cases include the Schwarzschild singularity, the Friedmann-Lemaître-Robertson-Walker Big Bang singularity, isotropic singularities, and a class of warped product singularities. This equation is constructed in terms of the Ricci part of the Riemann curvature (as the Kulkarni-Nomizu product between Einstein’s equation and the metric tensor).     

The Emergence of Social Order by Processes of Typifying: A Computational Model

The article argues that Rational Choice approaches are not sufficient to explain the “how” of the emergence of social order. Therefore, the concept of “typifying” according to the theory of Berger and Luckmann is understood as the most important form of establishing social orders between different social actors. A computational model is described that captures the basic features of the typifying process. Each artifical actor consists of two different neural nets, an “action net” and a “perception net”. These nets allow an actor to establish social rules of interaction with other actors, to remember the other actors after a time and to typify new actors as persons that belong to the same type as actors the first actor is already “acquainted” with. Experimental results and theoretical consequences are also given.     

On Uniform Exponential Trichotomy of Evolution Operators in Banach Spaces

This paper presents necessary and sufficient conditions for uniform exponential trichotomy of nonlinear evolution operators in Banach spaces. Thus are obtained results which extend well-known results for uniform exponential stability in the linear case.      

Parametric methods for frequency-selective MR spectroscopy-a review

Accurate quantitation of the spectral components in a pre-selected frequency band for magnetic resonance spectroscopy (MRS) signals is a frequently addressed problem in the MR community. One obvious application for such a frequency-selective technique is to lower the computational burden in situations when the measured data sequence contains too many samples to be processed using a standard full-spectrum method. Among the frequency-selective methods previously proposed in the literature, only a few possess the two features of primary concern: high robustness against interferences from out-of-band components and low computational complexity. In this survey paper we consider five spectral analysis methods which can be used for MRS signal parameter estimation in a selected frequency band. We re-derive the filter diagonalization method (FDM) in a new way that allows an easy comparison to the other methods presented. Then we introduce a frequency-selective version of the method of direction estimation (MODE) which has not been applied to MR-spectroscopy before. In addition, we present a filtering and decimation technique using a maximum phase bandpass FIR-filter and relate it to a similar ARMA-modeling approach known as SB-HOYWSVD (sub-band high-order Yule-Walker singular value decomposition). Finally, we study the numerical performances of these four methods and compare them to that of the recently introduced SELF-SVD (Singular Value Decomposition-based method usable in a SELected Frequency band) in several examples using simulated MR data, and discuss the benefits and disadvantages of each technique.     

Backward Stochastic Differential Equations Associated to a Symmetric Markov Process

We consider a second order semi-elliptic differential operator L with measurable coefficients, in divergence form, and the semilinear parabolic system of PDEs

Hybrid Nanomaterial Architectures: Combining Layers of Carbon Nanowalls,Nanotubes, and Particles

The paper focuses on the integration in hybrid architectures of plasma produced nanomaterials. The routes for the fabrication of layered structures consisting of carbon nanowalls on carbon nanotubes (CNW/CNT), of carbon nanotubes on carbon nanowalls (CNT/CNW), and nanoparticles on carbon nanowalls (NP/CNW) are presented. The morphology and structure of the hybrid architectures were investigated by electron microscopy techniques. We show that higher substrate temperature promotes the formation of high mass hydrogenated carbon clusters which favors the dominance of CNW growth over that of CNT. On this basis, a procedure of obtaining CNT/CNW architectures by switching the growth regime via substrate temperature is described. The specific limitations or advantages concerning the control or the properties of the obtained architectures are discussed.     

Barium strontium titanate-based perovskite materials for microwave applications

Ba_1−xSr_xTiO₃ solid solutions were prepared by solid-state reaction from raw materials. Four compositions with x = 0.25, 0.50, 0.75 and 0.90 have been investigated. The perovskite type and polycrystalline structure of the BST samples were revealed by X-ray diffraction data. The morphology, grain size distribution, porous structure and elemental composition of the sintered ceramics were analyzed by using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) microanalysis. The temperature dependence of permittivity and of dielectric loss tangent at low frequency (1 kHz) showed decrease of Curie temperature with increase of Sr content. Microwave measurements (1 GHz) showed substantial decrease of the dielectric constant from about 1600 to 200 and also of the losses from 12% to less than 2% with the Sr concentration increase from x = 0.25 to x = 0.90. Moreover, the addition of MgO and MnO₂ 1 wt.% each, improved sintering process and lowered the microwave losses up to 0.2%.