Interictal spike detection using the Walsh transform

The objective of this study was to evaluate the feasibility of using the Walsh transformation to detect interictal spikes in electroencephalogram (EEG) data. Walsh operators were designed to formulate characteristics drawn from experimental observation, as provided by medical experts. The merits of the algorithm are: 1) in decorrelating the data to form an orthogonal basis and 2) simplicity of implementation. EEG recordings were obtained at a sampling frequency of 500 Hz using standard 10-20 electrode placements. Independent sets of EEG data recorded on 18 patients with focal epilepsy were used to train and test the algorithm. Twenty to thirty minutes of recordings were obtained with each subject awake, supine, and at rest. Spikes were annotated independently by two EEG experts. On evaluation, the algorithm identified 110 out of 139 spikes identified by either expert (True Positives = 79%) and missed 29 spikes (False Negatives = 21%). Evaluation of the algorithm revealed a Precision (Positive Predictive Value) of 85% and a Sensitivity of 79%. The encouraging preliminary results support its further development for prolonged EEG recordings in ambulatory subjects. With these results, the false detection (FD) rate is estimated at 7.2 FD per hour of continuous EEG recording.     

Computation of radiative Marangoni (thermocapillary) magnetohydrodynamic convection in a Cu-water based nanofluid flow from a disk in porous media: Smart coating simulation

With emerging applications for smart and intelligent coating systems in energy, there has been increasing activity in researching magnetic nanomaterial coating flows. Surface tension features significantly in such regimes, and in the presence of heat transfer, Marangoni (thermocapillary) convection arises. Motivated by elaborating deeper the intrinsic transport phenomena in such systems, in this paper, a mathematical model is developed for steady radiative heat transfer and Marangoni magnetohydrodynamic flow of a Cu-water nanofluid influencing a strong magnetic field through a porous disk. The semianalytical adomain decomposition method is employed to find the solution of flow governing equations, which are reduced into ordinary differential equation form via the Von Karman similarity transformation. Validation with a generalized differential quadrature algorithm is included. The response in dimensionless velocity, temperature, wall heat transfer rate and shear stress is investigated for various values of the control parameters. Temperature is reduced with increasing Marangoni parameter, whereas the flow is accelerated. With increasing permeability parameter, the temperatures are elevated. Increasing radiative flux boosts temperatures further from the disk surface. Increasing magnetic parameter strongly dampens the boundary layer flow and elevates the temperatures, also eliminating temperature oscillations at lower magnetic field strengths.     

NBTI related time-dependent variability of mobility and threshold voltage in pMOSFETs and their impact on circuit performance

Threshold voltage (V_T) and mobility (μ) shifts due to process related variability and Negative Bias Temperature Instability are experimentally characterized in pMOSFETs. A simulation technique to include the time-dependent variabilities of V_T and μ in circuit simulators is presented and used to evaluate their effects on CMOS inverters performance. The results show that mobility degradation under NBTI stresses could have to be considered for the evaluation of the circuit performance after device aging.     

Structural changes in marinated fillets of gilthead sea bream (Sparus aurata L.) during vacuum storage at refrigerated temperature

Fillets of Sparus aurata were marinated in a mixture of salt (5.5%) and citric acid (48.9 g/kg) for 1 h, then vacuum packed and refrigerated for 1, 5, 16, and 21 d. Structural and ultrastructural parameters were evaluated in 6 specimens per time period. At day 1, the preservative solution appeared among the muscle fibers, thus increasing the interfibrillar spaces; cytoplasmic organelles were swollen and the sarcolemma-endomysium appeared very altered and electron-dense. At 5 to 10 d, the marinade solution had penetrated into the muscle fibers. The subsarcolemmal and intermyofibrillar spaces were dilated and granular lines of electron-dense material appeared among the fibers. From 16 d, broad interfibrillar spaces were occupied by granular material derived from denatured sarcolemma-endomysium and denatured myofibrils. Sarcomeres were already altered from initial stages, mainly at the I-band level. The Z-line also appeared disrupted. Such alterations were more severe from 10 d on, such that most of the sarcomeres showed disintegration of myofilaments.     

The Effect of Non-Equilibrium Condensation on Supersonic Air Flows over Rectangular Cavities

Numerical simulations have been carried out for a supersonic two-dimensional flow over open,rectangular cavi-ties(length-to-depth ratios are L/D=1.0 and 3.0)in order to investigate the effect of non-equilibrium condensa-tion of moist air on supersonic internal flows around the cavity for the flow Mach number 1.83 at the cavity en-trance.In the present computational investigation,a condensing flow was produced by an expansion of moist airin a Laval nozzle.The computational results showed that the upstream traveling compression waves becomeweaker than those without the condensation.Consequently,the weaker compression waves cannot excite theshear layer strongly and amplitudes of oscillation in the cavity became smaller than those without the condensa-tion.The occurrence of the non-equilibrium condensation in case of L/D=1.0 affected strongly the amplitude andfrequency of oscillation in the cavity compared with L/D=3.0.     

Structural and surface energy analysis of nitrogenated ta-C films

Surface and bulk properties of the Filtered Cathodic Vacuum Arc prepared nitrogenated tetrahedral amorphous carbon (ta-C:N) films were characterized by X-ray Photoelectron Spectroscopy (XPS), Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS), Raman spectroscopy, Atomic Force microscopy and contact angle techniques. An increase in the Nitrogen (N) content of the films is accompanied by a reduction in the sp³ fraction, confirmed via the deconvolution of the C 1 s XPS spectra. Critical Raman parameters such as peak position and peak width of the G band, defect ratio, I_D/I_G and skewness of the G line were analyzed as a function of N content. ToF-SIMS showed the variance of chemical composition with the increase in the sputtering depth. While some amount of incorporated oxygen and hydrogen were observed for all films; for high N content ta-C:N films signature of CN bonds was evident. Surface energies (both polar and dispersive components) for these ta-C:N films were analyzed in a geometric mean approach. Contact angle measurements using both deionized water and ethylene glycol reveal that upon the insertion of nitrogen into ta-C films, the initial change in the contact angle is sharp, followed by a gradual decrease with subsequent increase in N content. The variation of contact angle with increasing N content corresponds to an increase of the total surface energy with an increase of the polar component and a decrease of the dispersive component.     

Fabrication of and performance studies on a low cost solar cooker having an inclined aperture plane

A low cost box-type solar cooker made of two paper carton boxes with crumpled newspaper balls as insulation has been fabricated with a tilted aperture plane. Comparative tests of this cooker have been conducted against a normal type costlier solar cooker with 1000 ml load of water in each of the cookers. It has been observed that on a sunny day water temperature initially increases more rapidly in the new cooker compared to the normal type cooker. But at temperatures higher than 90°C both the cookers perform similarly. Two figures of merit F₁ and F₂ have also been found to be satisfactory. An arrangement of low cost auxiliary heating using a 100w electric bulb inside a blackened metal casing allows the carton box cooker to reach cooking temperatures under cloudy conditions with ease when the normal type solar cooker fails. The cost of materials for the new cooker is within US $10 and has been observed to be as effective as the normal type solar cooker which requires between US $40 and $65 to fabricate.     

Water Plasticization and Crystallization of Lactose in Spray-dried Lactose/Protein Mixtures

ABSTRACT: Water plasticization led to depression of the glass transition causing significant changes in the physico-chemical and crystallization properties in storage of lactose and lactose/protein (3:1) mixtures. Glass transition (Tg) and crystallization temperatures (Tcr) were determined using differential scanning calorimetry. Whey protein isolate (WPI), albumin, and gelatin increased the Tg of dry powders; when Na-caseinate was used, a decrease was observed. In the presence of proteins and water, a decrease of Tg at aw ≤ 0.23 was observed. At aw ≤ 0.33, proteins increased the Tg In the anhydrous state, Tcr decreased in the presence of proteins possibly because of browning. WPI, Na-caseinate, albumin, and gelatin delayed lactose crystallization in humidified samples, with albumin and gelatin delaying it more than WPI at all storage humidities. Temperature difference between an observed instant crystallization and glass transition (Tcr to Tg) was larger for humidified samples containing proteins than for lactose. Various proteins and water affect crystallization behavior of amorphous lactose differently in spray-dried powders. This should be considered in evaluating sugar crystallization properties in food products including dairy powders.     

A reduced chemical kinetic model for HCCI combustion of primary reference fuels in a rapid compression machine

A model for the Homogeneous Charge Compression Ignition (HCCI) of Primary Reference Fuels (PRFs) in a Rapid Compression Machine (RCM) has been developed. A reduced chemical kinetic model that included 32 species and 55 reactions was used and the affect of wall heat transfer on the temperature of the adiabatic core gas was taken into account by adding the displacement volume of the laminar boundary layer to the cylinder volume. A simple interaction between n-heptane and iso-octane was also included. The results showed the well-known two-stage ignition characteristics of heavy hydrocarbons, which involve low and high temperature cycles followed by a branched chain explosion. The first stage energy release decreases and the ignition delay increases nonlinearly with increasing octane number and decreasing the initial pressure. The energy release rate and total energy released were determined primarily by the rate of CO oxidation during the explosive phase following the ignition delay. The model reproduced the pressure curves obtained in the RCM experiments over a wide range of conditions remarkably well and was very sensitive to the fuel structure, the mixture composition and the initial temperature and pressure. Thus, the model can be easily adapted for predicting “knock” in spark-ignition engines and ignition-delays and burning rates in HCCI engines.