Enhanced sequence detector in the presence of intersymbol interference and non-Gaussian noise

A new Viterbi equaliser is proposed for joint mitigation of intersymbol interference and impulsive noise. The new equaliser uses a robust branch metric incorporating the Talwar penalty function. It is shown that the proposed equaliser facilitates considerable performance improvements.     

Temperature programmed decomposition (TPDE) of [Mo(CO)(6)] on metal oxide supports: a novel tool to elucidate surface acidity and surface-mediated reactions

A novel technique, the temperature programmed decomposition (TPDE) of [Mo(CO)(6)], has been developed to examine surface acid/base properties. In particular, the nucleophility of different surface hydroxyl groups can be quantified with this method, and it is found that the activation energy for decarbonylation of the carbonyl complex correlates well with the field strength of the metal cations in the support. Activation energies are derived from the CO peak maxima in the TPDE spectra by means of the Redhead equation. TPDE is also used to probe surface-mediated reactions of metal carbonyls. The technique enables identification of intermediates formed during the thermal decomposition process. Comparison with simulated TPDE spectra provides evidence for cluster formation during decarbonylation. By quantifying the amounts of CO and H(2) generated during the TPDE reaction, the surface concentration of the adsorbed species and the oxidation state of the central atom can be deduced at any given temperature.     

Optimal Control of Cancer Chemotherapy with Delays and State Constraints

Journal of Optimization Theory and Applications - A mathematical model of cancer chemotherapy is considered as an optimal control problem with the objective of either minimizing a weighted sum of...     

Effect of post-deposition annealing temperature on CeO2 thin film deposited on silicon substrate via RF magnetron sputtering technique

Physical and electrical properties of CeO₂ thin film deposited on p-type silicon substrate via the RF magnetron sputtering technique after treating in argon ambient at different annealing temperatures has been investigated and reported. Thickness of the CeO₂ thin film was in the range of 30–40 nm measured by an ellipsometer at 5 different points for each sample. Post-deposition annealing was executed in argon ambient for 30 min at four different temperatures (400, 600, 800, and 1000 °C). The physical results demonstrated that the thin film was free of physical defects and root-mean square surface roughness decreased as the annealing temperature increased. X-ray diffraction indicated the occurrence of CeO₂ phase with four diffraction planes [(1 1 1), (2 0 0), (2 2 0), and (3 1 1)]. All samples showed negative flat band voltage shift owing to the existence of positive effective oxide charges. Samples annealed at 1000 °C showed the lowest interface trap density, total interface trap density, effective oxide charge, and the highest barrier height. This attributed to the lowest leakage current density (∼1×10⁻⁹ A cm⁻²) and the highest electric breakdown voltage (∼30 V) of the sample when a comparison was made.     

Race Conditions in Coexisting Overlay Networks

By allowing end hosts to make independent routing decisions at the application level, different overlay networks may unintentionally interfere with each other. This paper describes how multiple similar or dissimilar overlay networks could experience race conditions, resulting in oscillations (in both route selection and network load) and cascading reactions. We pinpoint the causes for synchronization and derive an analytic formulation for the synchronization probability of two overlays. Our model indicates that the probability of synchronization is non-negligible across a wide range of parameter settings, thus implying that the ill effects of synchronization should not be ignored. Using the analytical model, we find an upper bound on the duration of traffic oscillations. We also show that the model can be easily extended to include a large number of co-existing overlays. We validate our model through simulations that are designed to capture the transient routing behavior of both the IP- and overlay-layers. We use our model to study the effects of factors such as path diversity (measured in round trip times) and probing aggressiveness on these race conditions. Finally, we discuss the implications of our study on the design of path probing process in overlay networks and examine strategies to reduce the impact of race conditions.     

Nonlinear BER performance of dense optical WDM manhattan street network with deflection routing

The nonlinear bit-error-rate (BER) performance of dense optical wavelength-division-multiplexed (WDM) Manhattan Street Networks with deflection routing was evaluated using an extendable semianalytical process. The results show that nonlinear effects impose significant performance penalties on dense WDM networks, both in terms of maximum hops attainable and average BER, and should be taken into account when modeling such networks. Simple techniques such as optimal amplifier positioning can reduce the nonlinear penalties.     

Using Nanoparticle Tracking Analysis (NTA) to Decipher Mucoadhesion Propensity of Curcumin-Containing Chitosan Nanoparticles and Curcumin Release

Real-time nanoparticle tracking analysis (NTA) was used to evaluate the propensity of curcumin-containing chitosan nanoparticles (CUR-CS-NP) to muco adhere and release curcumin under simulated colon conditions. This novel procedure is relatively simple and fast and does not require use of animals, but more importantly, it permits the correlation of physical changes to the CUR-CS-NP with the observed behavior under simulated conditions in realtime. The CUR-CS-NP formed spontaneous aggregates in response to exposure to mucin. This observation correlated with curcumin release from CUR-CS-NP was observed in phosphate buffer (pH 7.4) where, 81% of curcumin was released within 6 hours. Atomic force microscopy imaging CUR-CS-NP exposed to mucin solution revealed a decorated surface of the CUR-CS-NP by mucin, consistent with expected electrostatic interactions between the two. The use of NTA, thus, provided us with a means of ascertaining the performance of the CUR-CS-NP under simulated colonic conditions and we propose that this prototype delivery system could be the basis for an effective colon mucoadhesive drug delivery system.      

An integrated solid-state solution for secondary electron detection

In this paper, a novel integrated solid-state solution is proposed to replace the vacuum-based photomultiplier tube and other constituent components of the Everhart–Thornley detector, which has been widely used for secondary electron detection in scanning electron microscopy. Compared to the conventional setup, this integrated circuit offers potential merits such as higher cost effectiveness, smaller dimensions, lower voltage and power requirements, and better circuit integration. It was designed and fabricated in an optically-enhanced Austriamicrosystems 0.35 μm CMOS process technology. Results from simulations and experiments have shown that the solid-state detector can operate with a maximum transimpedance gain of 170 dBΩ and minimum bandwidth of 3.6 MHz. It can detect signals with optical power as low as 10 nW while giving a minimum signal-to-noise ratio of 24 dB regardless of gain configuration.     

Impact of Packet Sampling on Portscan Detection

Packet sampling is commonly deployed in high-speed backbone routers to minimize resources used for network monitoring. It is known that packet sampling distorts traffic statistics and its impact has been extensively studied for traffic engineering metrics such as flow size and mean rate. However, it is unclear how packet sampling impacts anomaly detection, which has become increasingly critical to network providers. This paper is the first attempt to address this question by focusing on one common class of nonvolume-based anomalies, portscans, which are associated with worm/virus propagation. Existing portscan detection algorithms fall into two general approaches: target-specific and traffic profiling. We evaluated representative algorithms for each class, namely: 1) TRWSYN that performs stateful traffic analysis; 2) TAPS that tracks connection pattern of scanners; and 3) entropy-based traffic profiling. We applied these algorithms to detect portscans in both the original and sampled packet traces from a Tier-1 provider's backbone network. Our results demonstrate that sampling introduces fundamental bias that degrades the effectiveness of these detection algorithms and dramatically increases false positives. Through both experiments and analysis, we identify the traffic features critical for anomaly detection that are affected by sampling. Finally, using insight gained from this study, we show how portscan algorithms can be enhanced to be more robust to sampling     

A phase matrix for a dense discrete random medium: evaluation ofvolume scattering coefficient

In the derivation of the conventional scattering phase matrix of a discrete random medium, the far-field approximation is usually assumed. In this paper, the phase matrix of a dense discrete random medium is developed by relaxing the far-field approximation and accounting for the effect of volume fraction and randomness properties characterized by the variance and correlation function of scatterer positions within the medium. The final expression for the phase matrix differs from the conventional one in two major aspects: there is an amplitude and a phase correction. The concept used in the derivation is analogous to the antenna array theory. The phase matrix for a collection of scatterers is found to be the Stokes matrix of the single scatterer multiplied by a dense medium phase correction factor. The close spacing amplitude correction appears inside the Stokes matrix. When the scatterers are uncorrelated, the phase correction factor approaches unity. The phase matrix is used to calculate the volume scattering coefficients for a unit volume of spherical scatterers, and the results are compared with calculations from other theories, numerical simulations, and laboratory measurements. Results indicate that there should be a distinction between physically dense medium and electrically dense medium