Cytotoxicity and tolerance to DNA adducts of alicyclic mixed amine platinum(II) homologs in tumor models sensitive and resistant to cisplatin or tetraplatin

Structure-cytotoxicity relationships for six alicyclic cis-(NH3)(R-NH2)Cl2Pt(II) complexes, where R=C3H5, C4H7, C5H9, C6H11, C7H13 and C8H15 (complexes abbreviated C3, C4, C5, C6, C7 and C8, respectively), were evaluated against four sensitive (L1210/0, A2780, FSaIIC and Colon 26), two cisplatin-resistant (L1210/DDP and 2780CP) and two tetraplatin-resistant (L1210/DACH and 2780TP) murine and human tumor cell lines. The studies demonstrated that in general the structure of C6 was optimal within the homologous series for cytotoxic potency against these tumor models. Biochemical pharmacologic studies indicated that the greater sensitivity of cells to C6 could be correlated with their low tolerance to DNA damage induced by this homolog. These results provide evidence for the alicyclic ring size as a structural determinant of DNA damage tolerance and anti-tumor activity in sensitive and resistant tumor cells.     

Self-digestion of human erythrocyte membranes. Role of adenosine triphosphate and glutathione

Intact human erythrocytes incubated at 37 degrees C, pH7.4, release a sialoglycopeptide similar in its chemical composition, immunological and aggregation properties to the glycopeptide released by isolated 'ghost' membranes. The presence of ATP or reduced glutathione at physiological concentrations in the incubation medium of 'ghost' membranes inhibits this self-digestion process.     

Synthesis and properties of zirconia thin films

Thin films of zirconia have been synthesized using reactive DC magnetron sputtering. It has been found that films with good optical constants, high refractive index (1·9 at 600 nm) and low extinction coefficient can be prepared at ambient temperatures. The optical constants and band gap and hence the composition are dependent on the deposition parameters such as target power, rate of deposition and oxygen background pressure. Thermal annealing of the films revealed that the films showed optical and crystalline inhomogeneity and also large variations in optical constants.     

Diffusion Based Channel Gains Estimation in WSN Using Fractional Order Strategies

In this study, it is proposed that the diffusion least mean square (LMS) algorithm can be improved by applying the fractional order signal processing methodologies. Application of Caputo’s fractional derivatives are considered in the optimization of cost function. It is suggested to derive a fractional order variant of the diffusion LMS algorithm. The applicability is tested for the estimation of channel parameters in a distributed environment consisting of randomly distributed sensors communicating through wireless medium. The topology of the network is selected such that a smaller number of nodes are informed. In the network, a random sleep strategy is followed to conserve the transmission power at the nodes. The proposed fractional order modified diffusion LMS algorithms are applied in the two configurations of combine-then-adapt and adapt-then-combine. The average squared error performance of the proposed algorithms along with its traditional counterparts are evaluated for the estimation of the Rayleigh channel parameters. A mathematical proof of convergence is provided showing that the addition of the nonlinear term resulting from fractional derivatives helps adjusts the autocorrelation matrix in such a way that the spread of its eigenvalues decreases. This increases the convergence as well as the steady state response even for the larger step sizes. Experimental results are shown for different number of nodes and fractional orders. The simulation results establish that the accuracy of the proposed scheme is far better than its classical counterparts, therefore, helps better solves the channel gains estimation problem in a distributed wireless environment. The algorithm has the potential to be applied in other applications related to learning and adaptation.     

On accounting for screen resolution in adaptive video streaming: QoE-driven bandwidth sharing framework

Screen resolution along with network conditions are main objective factors impacting the user experience, in particular for video streaming applications. User terminals on their side feature more and more advanced characteristics resulting in different network requirements for good visual experience. Previous studies tried to link mean opinion score (MOS) to video bitrate for different screen types (e.g., Common Intermediate Format [CIF], Quarter Common Intermediate Format [QCIF], and High Definition [HD]). We leverage such studies and formulate a Quality of Experience (QoE)-driven resource allocation problem to pinpoint the optimal bandwidth allocation that maximizes the QoE over all users of a network service provider located behind the same bottleneck link, while accounting for the characteristics of the screens they use for video playout. For our optimization problem, QoE functions are built using curve fitting on datasets capturing the relationship between MOS, screen characteristics, and bandwidth requirements. We propose a simple heuristic based on Lagrangian relaxation and Karush Kuhn Tucker (KKT) conditions to efficiently solve the optimization problem. Our numerical simulations show that the proposed heuristic is able to increase overall QoE up to 20% compared to an allocation with a TCP look-alike strategy implementing max-min fairness.     

A Distributed and Elastic Application Processing Model for Mobile Cloud Computing

The latest developments in mobile computing technology have increased the computing capabilities of smart mobile devices (SMDs). However, SMDs are still constrained by low bandwidth, processing potential, storage capacity, and battery lifetime. To overcome these problems, the rich resources and powerful computational cloud is tapped for enabling intensive applications on SMDs. In Mobile Cloud Computing (MCC), application processing services of computational clouds are leveraged for alleviating resource limitations in SMDs. The particular deficiency of distributed architecture and runtime partitioning of the elastic mobile application are the challenging aspects of current offloading models. To address these issues of traditional models for computational offloading in MCC, this paper proposes a novel distributed and elastic applications processing (DEAP) model for intensive applications in MCC. We present an analytical model to evaluate the proposed DEAP model, and test a prototype application in the real MCC environment to demonstrate the usefulness of DEAP model. Computational offloading using the DEAP model minimizes resources utilization on SMD in the distributed processing of intensive mobile applications. Evaluation indicates a reduction of 74.6% in the overhead of runtime application partitioning and a 66.6% reduction in the CPU utilization for the execution of the application on SMD.

     

Measurements of radio channels and bit error rate estimation of IEEE802.16 standard in semi-rural environment at three frequencies in the 2?6 GHz frequency band

Simultaneous measurements with 10 MHz bandwidth at 2.5, 3.5 and 5.8 GHz were performed in a rural/semi-rural environment in the UK. The measurements were processed to generate power delay profiles to estimate the root mean square delay spread of the channel. The frequency range of the orthogonal frequency division multiplexing (OFDM) symbol bandwidth that has dropped below a predefined level, termed herein as average fade bandwidth, and the corresponding level crossing are employed to quantify the severity of frequency selectivity. The channel data were used to estimate the bit error rate, for the 256 carrier-OFDM IEEE802.16 standard using a frequency domain channel simulator especially designed for the study. It was found that the performance of quasi-stationary wireless broadband systems depends mainly upon the frequency selectivity and the channel coding rate with 1/2 rate coding giving a superior performance to 3/4 rate coding. Puncturing was found to weaken the capability of forward error correction coding in the presence of series of deep fades in the channel transfer function.