Parallel Channels for High Rate UTRAN

The method proposed in this paper uses space–time filtering to support parallel channel transmission as an effort to solve two main limitations facing UMTS Terrestrial Radio Access Network (UTRAN): throughput limitation and capacity limitation at high bit rates. The overall system capacity in the case of a spreading factor of 4 was enhanced by adding four channels, leading to a total physical layer throughput of 6.5 Mbps with a slight reduction in the performance of less than 1 dB for some users, while other users performance remain without any degradation. In another case where a spreading factor 8 was used adding four parallel channels leads to a total throughput of 5.1 Mbps with only 1.5 dB reduction in the performance of some users. Finally in the case of a spreading factor of 16, with a reduction of less than 3 dB in performance, an addition of eight parallel channels leads to a throughput of about 5 Mbps.     

Synthesis and anticancer activities of fatty acid analogs of podophyllotoxin

Derivatives of podophyllotoxin were prepared by coupling 10 FA with the C₄-α-hydroxy function of podophyllotoxin. The coupling reactions between FA and podophyllotoxin were carried out by dicyclohexylcarbodiimide in the presence of a catalytic amount of dimethylaminopyridine to produce quantitative yields of desired products. FA incorporated were the following: 10-hydroxydecanoic, 12-hydroxydodecanoic, 15-hydroxypentadecanoic, 16-hydroxyhexadecanoic, 12-hydroxyoctadec-Z-9-enoic, eicosa-Z-5,8,11,14-tetraenoic, eicosa-Z-8,11, 14-trienoic, eicosa-Z-11,14-dienoic, eicosa-Z-11-enoic, and eicosanoic acids. Spectroscopic studies confirmed the formation of the desired products. New molecules were investigated for their in vitro anticancer activity against a panel of human cancer cell lines including SK-MEL, KB, BT-549, SK-OV-3 (solid tumors), and HL-60 (human leukemia) cells. Most of the analogs were cytotoxic against cancerous cells, whereas no effect was observed against normal cells, unlike the parent compound podophyllotoxin, the use of which is limited due to its severe side effects.     

Pore diffusion and external mass transport during dye adsorption on to Fuller's earth and silica

The adsorption of dyes on to Fuller's earth and silica has been studied. A mass transfer model has been developed to describe the adsorption process based on external mass transfer and internal pore diffusion. Theoretical concentration decay curves have been predicted using the model and compared with experimental decay curves.     

Air-Impingement Drying of Tortilla Chips

Tortilla pieces were prepared from nixtamalized masa flour, and dried under impinging hot air. The effect of different drying conditions on the drying rate, texture, shrinkage profile and microstructure was analyzed. The results indicated that drying rate was mostly affected by the air temperature; texture was crispier at higher air temperatures: shrinkage of the piece was higher at lower convective heat transfer coeffieient; and microstructure looked smoother at higher air temperature.     

Identification of two electron-transfer sites in ascorbate peroxidase using chemical modification, enzyme kinetics, and crystallography

Chemical and mutagenic modification combined with X-ray crystallography has been used to probe the ascorbate binding site in ascorbate peroxidase (APX). Chemical modification of the single Cys residue in APX with Ellman's reagent (DTNB) blocks the ability of APX to oxidize ascorbate but not other small aromatic phenolic substrates. DTNB-modified APX (APX-TNB) exhibits only 1.3% wild-type activity when ascorbate is used as the substrate but full activity when aromatic substrates, guaiacol or pyrogallol, are used. Stopped-flow studies show that APX-TNB reacts normally with peroxide to give compound I but that the rates of reduction of both compounds I and II by ascorbate are dramatically slowed. Conversion of Cys32 to Ser leads to approximately 70% drop in ascorbate peroxidase activity with no effect on guaiacol peroxidase activity. These results indicate that uncharged aromatic substrates and the anionic ascorbate molecule interact with different sites on APX. The 2.0 A X-ray crystal structure of APX-TNB shows clear electron density for the TNB group covalently attached to Cys32 in all four molecules of the asymmetric unit, indicating complete and specific modification. It appears that the ascorbate site is blocked by DTNB modification which is well removed from the exposed delta-heme edge where aromatic substrates are thought to bind. This is the first experimental evidence indicating that ascorbate oxidation does not occur at the exposed heme edge but at an alternate binding site in the vicinity of Cys32 near Arg172 and the heme propionates.     

Computation of Scattering from Penetrable Cylinders with Improved Numerical Efficiency

An integral-equation formulation is used to obtain numerical results for the scattered fields of a penetrable cylinder immersed in either a lossy halfspace or a lossy homogeneous medium. The cylinder is iluminated by a parallel electric line source. A set of plane waves interior to the inhomogeneity (scatterer) is used as basis functions. This results in more than an order of magnitude decrease in the computer time required to obtain numerical results for larger sized targets. Further, the integral-equation solution is extended to include the planar interface between the air and the earth. The validity of the approximate forms proposed earlier to represent the interface is reexamined.     

Simultaneous Prediction of Saturated Hydraulic Conductivity and Drainable Porosity Using the Inverse Problem Technique

The saturated hydraulic conductivity K and the effective porosity f are two important input parameters needed for lateral drain spacing design, as well as some other applications. The technical and economic justification, of most drainage projects, is mainly connected to these two parameters. The current design procedure is based upon calculation of the lateral spacing, using some average values of K and f within the drainage area. The objectives of this study were to introduce a new method for simultaneous estimation of K and f parameters using the inverse problem technique, and to evaluate five different unsteady drainage analytical models of the Boussinesq equation, suggested by different researchers for simultaneous prediction of the parameters. Consequently, five different analytical models for predicting water table profiles were solved, using the inverse problem technique. Each model was then evaluated. A physical drainage model of 2.2?m length, 0.3?m width, and 0.5?m height was established in the laboratory and carefully packed with a sandy loam soil. A perforated drainage pipe of 4.5?cm in diameter was installed at the bottom end of the model. Many piezometers were inserted in the soil for spatial and temporal water table monitoring. Different data sets from the experiments and literature were used for model calibration. The newly proposed approach that is based upon measuring water table profiles, at different times, was then evaluated with both constant and variable f. The predicted values of the proposed approach indicated reasonable agreement with the measured data. With variable effective porosity, the method was even more accurate to predict the water table profiles. Using the inverse problem technique, all the analytical models provided good agreement with the measured data. Among these, however, the Topp and Moody model predicted more accurate results than other models.     

Finite mixture of gamma distributions: A conjugate prior

A finite mixture of gamma distributions [Finite mixture of certain distributions. Comm. Statist. Theory Methods 31(12), 2123-2137] is used as a conjugate prior, which gives a nice form of posterior distribution. This class of conjugate priors offers a more flexible class of priors than the class of gamma prior distributions. The usefulness of a mixture gamma-type prior and the posterior of uncertain parameters λ for the Poisson distribution are illustrated by using Markov Chain Monte Carlo (MCMC), Gibbs sampling approach, on hierarchical models. Using the generalized hypergeometric function, the method to approximate maximum likelihood estimators for the parameters of Agarwal and Al-Saleh [Generalized gamma type distribution and its hazard rate function. Comm. Statist. Theory Methods 30(2), 309-318] generalized gamma-type distribution is also suggested.     

A Novel Approach for Security Enhancement of Data Encryption Standard

Data Encryption Standard (DES) is a symmetric key cryptosystem that is applied in different cryptosystems of recent times. However, researchers found defects in the main assembling of the DES and declared it insecure against linear and differential cryptanalysis. In this paper, we have studied the faults and made improvements in their internal structure and get the new algorithm for Improved DES. The improvement is being made in the substitution step, which is the only nonlinear component of the algorithm. This alteration provided us with great outcomes and increase the strength of DES. Accordingly, a novel good quality S-box construction scheme has been hired in the substitution phase of the DES. The construction involves the Galois field method and generates robust S-boxes that are used to secure the scheme against linear and differential attacks. Then again, the key space of the improved DES has been enhanced against the brute force attack. The outcomes of different performance analyses depict the strength of our proposed substitution boxes which also guarantees the strength of the overall DES.