Enhancing Data Rates of TH-UWB Systems Using M-ary OPPM-BPSM Modulation Scheme: A System Perspective

This paper proposes and studies a combined modulation scheme for time hopping ultra wideband (TH-UWB) radio system based on orthogonal pulse position modulation (OPPM) and biorthogonal pulse shape modulation (BPSM). The proposed scheme offers a high data rate with satisfactory system performance by using high-level multi-dimensional modulation schemes. It allows one to increase the number of orthogonal pulses in each pulse position and, consequently, be able to adopt shorter pulse repetition intervals than those used in conventional M-ary OPPM or M-ary biorthogonal PPM (BPPM) modulation schemes. The performance is analyzed by using characteristic function and Gaussian approximation in additive white Gaussian and multipath scenarios, respectively. The proposed scheme reduces multiple access interference considerably in multi-user environments. Finally, simulation results are provided to validate the theoretical results.     

High performance TaYOx-based MIM capacitors

TaYO_x-based metal-insulator-metal (MIM) capacitors with excellent electrical properties have been fabricated. Ultra-thin TaYO_x films in the thickness range of 15-30 nm (EOT ∼ 2.4-4.7 nm) were deposited on Au/SiO₂ (100 nm)/Si (100) structures by rf-magnetron co-sputtering of Ta₂O₅ and Y₂O₃ targets. TaYO_x layers were characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) to examine the composition and crystallinity. An atomic percentage of Ta:Y = 58.32:41.67 was confirmed from the EDX analysis while XRD revealed an amorphous phase (up to 500 °C) during rapid thermal annealing. Besides, a high capacitance density of ∼3.7-5.4 fF/μm² at 10 kHz (ε_r ∼ 21), a low value of VCC (voltage coefficients of capacitance, α and β) have been achieved. Also, a highly stable temperature coefficient of capacitance, TCC has been obtained. Capacitance degradation phenomena in TaYO_x-based MIM capacitors under constant current stressing (CCS at 20 nA) have been studied. It is observed that degradation depends strongly on the dielectric thickness and a dielectric breakdown voltage of 3-5 MV/cm was found for TaYO_x films. The maximum energy storage density was estimated to be ∼5.69 J/cm³. Post deposition annealing (PDA) in O₂ ambient at 400 °C has been performed and further improvement in device reliability and electrical performances has been achieved.     

Evaluation of a droplet digital polymerase chain reaction format for DNA copy number quantification

Droplet digital polymerase chain reaction (ddPCR) is a new technology that was recently commercialized to enable the precise quantification of target nucleic acids in a sample. ddPCR measures absolute quantities by counting nucleic acid molecules encapsulated in discrete, volumetrically defined, water-in-oil droplet partitions. This novel ddPCR format offers a simple workflow capable of generating highly stable partitioning of DNA molecules. In this study, we assessed key performance parameters of the ddPCR system. A linear ddPCR response to DNA concentration was obtained from 0.16% through to 99.6% saturation in a 20,000 droplet assay corresponding to more than 4 orders of magnitude of target DNA copy number per ddPCR. Analysis of simplex and duplex assays targeting two distinct loci in the Lambda DNA genome using the ddPCR platform agreed, within their expanded uncertainties, with values obtained using a lower density microfluidic chamber based digital PCR (cdPCR). A relative expanded uncertainty under 5% was achieved for copy number concentration using ddPCR. This level of uncertainty is much lower than values typically observed for quantification of specific DNA target sequences using currently commercially available real-time and digital cdPCR technologies.     

Impacts of gate electrode materials on threshold voltage (V/sub th/) instability in nMOS HfO/sub 2/ gate stacks under DC and AC stressing

Ultrathin nMOSFET hafnium oxide (HfO/sub 2/) gate stacks with TiN metal gate and poly-Si gate electrodes are compared to study the impact of the gate electrode on long term threshold instability reliability for both dc and ac stress conditions. The poly-Si/high-/spl kappa/ interface exhibits more traps due to interfacial reaction than the TiN/high-/spl kappa/ interface, resulting in significantly worse dc V/sub th/ instability. However, the V/sub th/ instability difference between these two stacks decreases and eventually diminishes as ac stress frequency increases, which suggests the top interface plays a minor role in charge trapping at high operating frequency. In addition, ac stress induced interface states (Nit) can be effectively recovered, resulting in negligible G/sub m/ degradation.     

Development and performance evaluation of neural network classifiers for Indian internet shoppers

The rapid growth of usage of internet has paved the way towards the use of online shopping. Consumers’ behavior is one of the significant aspects that is considered by the service providers for the improvement of various services. Consumers are generally satisfied if their needs are fulfilled. In this paper an in depth investigation is made on the behavior of Indian consumers towards online shopping. Factor analysis is carried out to extract significant factors that affect online shopping of Indian consumers and these consumers are clustered based on their behavior, towards online shopping using hierarchical clustering. Employing the results of clustering in training of multilayer perceptron (MLP), functional link artificial neural network (FLANN) and radial basis function (RBF) networks efficient classifier models are developed. The performance of these classifiers are evaluated and compared with those obtained by conventional statistical based discriminant analysis. The simulation study demonstrates that the RBF network provides best classification performance of internet shoppers compared to those given by the FLANN, MLP and discriminant analysis based methods. The simulation study on the impact of different combination of inputs demonstrates that demographic input has least effect on classification performance. On the other hand the combination of psychological and cultural inputs play the most significant role in classification followed by psychological and then cultural inputs alone.     

Efficient prediction of stock market indices using adaptive bacterial foraging optimization (ABFO) and BFO based techniques

The present paper introduces the use of BFO and ABFO techniques to develop an efficient forecasting model for prediction of various stock indices. The structure used in these forecasting models is a simple linear combiner. The connecting weights of the adaptive linear combiner based models are optimized using ABFO and BFO by minimizing its mean square error (MSE). The short and long term prediction performance of these models are evaluated with test data and the results obtained are compared with those obtained from the genetic algorithm (GA) and particle swarm optimization (PSO) based models. It is in general observed that the new models are computationally more efficient, prediction wise more accurate and show faster convergence compared to other evolutionary computing models such as GA and PSO based models.     

Electrical observation of deep traps in high-/spl kappa//metal gate stack transistors

The instability of threshold voltage in high-/spl kappa//metal gate devices is studied with a focus on the separation of reversible charge trapping from other phenomena that may contribute to time dependence of the threshold voltage during a constant voltage stress. Data on the stress cycles of opposite polarity on both pMOS and nMOS transistor suggests that trapping/detrapping at the deep bandgap states contributes to threshold voltage instability in the pMOS devices. It is found that under the same electric field stress conditions, threshold voltage changes in pMOS and nMOS devices are nearly identical.     

On-line PI control of stable processes

A relay based on-line automatic tuning method for PI controllers for stable processes is presented. In the proposed method, prior to controller re-tuning a relay in tandem with the controller and plant induces limit cycle oscillations. Based on the limit cycle measurements, a first order plus dead time (FOPDT) model of the process dynamics is obtained. Simple tuning rules based on ISTE performance criterion and the first order model are developed. The controller settings may be re-tuned non-iteratively to achieve enhanced performance without disrupting closed loop control. A number of simulation examples are given to illustrate the potential advantages of the proposed on-line tuning method.     

Improved Ge Surface Passivation With Ultrathin SiOX Enabling High-Mobility Surface Channel pMOSFETs Featuring a HfSiO/WN Gate Stack

To realize high-mobility surface channel pMOSFETs on Ge, a 1.6-nm-thick SiO_X passivation layer between the bulk Ge substrate and HfSiO gate dielectric was introduced. This approach provides a simple alternative to epitaxial Si deposition followed by selective oxidation and leads to one of the highest peak hole mobilities reported for unstrained surface channel pMOSFETs on Ge: 332 cm² middotV^-1middots^-1 at 0.05 MV/cm-a 2times enhancement over the universal Si/SiO₂ mobility. The devices show well-behaved output and transfer characteristics, an equivalent oxide thickness of 1.85 nm and an I_ON/I_OFF ratio of 3times10³ without detectable fast transient charging. The high hole mobility of these devices is attributed to adequate passivation of the Ge surface     

Liposomes Targeting P21 Activated Kinase-1 (PAK-1) and Selective for Secretory Phospholipase A2 (sPLA2) Decrease Cell Viability and Induce Apoptosis in Metastatic Triple-Negative Breast Cancer Cells

P21 activated kinases (or group I PAKs) are serine/threonine kinases whose expression is altered in prostate and breast cancers. PAK-1 activity is inhibited by the small molecule “Inhibitor targeting PAK-1 activation-3” (IPA-3), which has selectivity for PAK-1 but is metabolically unstable. Secretory Group IIA phospholipase A₂ (sPLA₂) expression correlates to increased metastasis and decreased survival in many cancers. We previously designed novel liposomal formulations targeting both PAK-1 and sPLA_2, called Secretory Phospholipase Responsive liposomes or SPRL-IPA-3, and demonstrated their ability to alter prostate cancer growth. The efficacy of SPRL against other types of cancers is not well understood. We addressed this limitation by determining the ability of SPRL to induce cell death in a diverse panel of cells representing different stages of breast cancer, including the invasive but non-metastatic MCF-7 cells, and metastatic triple-negative breast cancer (TNBC) cells such as MDA-MB-231, MDA-MB-468, and MDA-MB-435. We investigated the role of sPLA₂ in the disposition of these liposomes by comparing the efficacy of SPRL-IPA-3 to IPA-3 encapsulated in sterically stabilized liposomes (SSL-IPA-3), a formulation shown to be less sensitive to sPLA₂. Both SSL-IPA-3 and SPRL-IPA-3 induced time- and dose-dependent decreases in MTT staining in all cell lines tested, but SPRL-IPA-3-induced effects in metastatic TNBC cell lines were superior over SSL-IPA-3. The reduction in MTT staining induced by SPRL-IPA-3 correlated to the expression of Group IIA sPLA₂. sPLA₂ expression also correlated to increased induction of apoptosis in TNBC cell lines by SPRL-IPA-3. These data suggest that SPRL-IPA-3 is selective for metastatic TNBC cells and that the efficacy of SPRL-IPA-3 is mediated, in part, by the expression of Group IIA sPLA₂.