A flexible dynamic traffic model for reverse link CDMA cellular networks

In this paper, we focus on the reverse link traffic analysis of a code-division multiple-access (CDMA) cellular network in dynamic environments. In this respect, we propose a new and flexible traffic model, which takes into account the interference-limitedness attribute of CDMA capacity as well as its soft-handoff feature. This new traffic model is developed according to an interference-based call admission control (ICAC) method and a geographical structure with three regions. The main advantage of this traffic model is in its flexibility when we consider different traffic conditions including time-varying status of traffic in the neighboring cells.     

A contribution to the thermal decomposition of salts and metal complexes of 1,1-dithiolates

Summary The thermal decomposition of salts and metal complexes (binary and mixed ligand) of dithiocarbamates, xanthates, dithiocarbazates and dithiophosphates has been studied thermogravimetrically. The activation energies of decomposition for some of them were calculated adopting the Coats and Redfern equation. In most cases the binary complexes decompose in a single sharp stage whereas the mixed ligand complexes are characterised by decompositions having more than one stage.     

Mesoporous cadmium sulfide nanoparticles derived from a new cadmium anthranilato complex: Characterization and induction of morphological abnormalities in pathogenic fungi

A cadmium complex of the general formula Cd(C₁₃H₉O₂NCl)₂(H₂O)₂ {C₁₃H₉O₂NCl = 2-(4-chlorophenylamino)benzoate} was synthesized and characterized regarding its CHN data, solution molar conductivity and spectroscopic (UV–Vis. and IR) properties. Cadmium sulfide nanoparticles (CdS NPs) were grown form the microcrystalline complex and thiourea via a hydrothermal route. The as-prepared NPs were assigned based on X-ray powder diffraction (PXRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and Brunauer – Emmett – Teller (BET) surface area measurements. The CdS absorption and emission spectra were also recorded that revealed an energy gap of 2.47 eV and large Stokes shift of 130 nm. For the as-prepared NPs, the measurements have also indicated a mesoporous structure and an average particle size of 20–28 nm associated with an average pore diameter of 11.21 nm. The as-synthesized CdS NPs acted as antifungal controlling agent against human and plant pathogenic fungi of serious environmental and health concerns. The NPs at concentration of 200 ppm inhibited several fungi with inhibition efficiency of 100% against Aspergillus ustus Au-28. The nanoparticles induced morphological abnormalities in fungal mycelia, conidia and vesicle. Additionally, they inhibited the conidia septum formation, accelerated the chlamydospores generation and enlarged the yeast cells.     

Cohomology in superstring field theory and properties of D-branes

The paper presents recent achievements and open questions in string field theory that are related to the cohomology of BRST operators. We sketch the construction of a nonpolynomial action based on cubic theory that uses the triviality of the BRST operator in the so-called large algebra. We also construct special solutions of equations of motion in superstring field theory and study the cohomology of a modified BRST operator near these solutions.     

String field theory: From high energy to cosmology

We review recent achievements and open questions in string field theory. We comment on the history of the construction of the covariant gauge-invariant string field formulation and briefly consider possible applications of string field theory in D-brane physics and cosmology.     

Study of the eigenwaves of a coplanar transmission line using the method of partial operator inversion

We propose a partial inversion procedure for the Cauchy singular integral and the integral with a logarithmic singularity determined on a finite set of bounded intervals. On the basis of this procedure, we constructed an electrodynamic model of a shielded coplanar transmission line (CTL). The results of calculation of the spectral characteristics and eigenwave field distributions of this structure are presented and the data on convergence of the approximate solution are given. Volga State Academy of Telecommunications and Information Sciences, Samara, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 43, No. 6, pp. 552–561, June, 2000.     

Holographic thermalization in a quark confining background

Journal of Experimental and Theoretical Physics - We study holographic thermalization of a strongly coupled theory inspired by two colliding shock waves in a vacuum confining background....     

Spectra of some block operator matrices and application to transport operators

In this paper a new concept for a 3×3 block operator matrix is studied on a Banach space. It is shown that, under certain conditions, it defines a closable operator and its essential spectra are determined. Application to transport operators in L₁-space is given.     

Bounds on the Sum Capacity of Synchronous Binary CDMA Channels

In this paper, we obtain a family of lower bounds for the sum capacity of code-division multiple-access (CDMA) channels assuming binary inputs and binary signature codes in the presence of additive noise with an arbitrary distribution. The envelope of this family gives a relatively tight lower bound in terms of the number of users, spreading gain, and the noise distribution. The derivation methods for the noiseless and the noisy channels are different but when the noise variance goes to zero, the noisy channel bound approaches the noiseless case. The behavior of the lower bound shows that for small noise power, the number of users can be much more than the spreading gain without any significant loss of information (overloaded CDMA). A conjectured upper bound is also derived under the usual assumption that the users send out equally likely binary bits in the presence of additive noise with an arbitrary distribution. As the noise level increases, and/or, the ratio of the number of users and the spreading gain increases, the conjectured upper bound approaches the lower bound. We have also derived asymptotic limits of our bounds that can be compared to a formula that Tanaka obtained using techniques from statistical physics; his bound is close to that of our conjectured upper bound for large scale systems.