Functional near-infrared neuroimaging.

Functional near-infrared spectroscopy (fNIR) is a neroimaging modality that enables continuous, noninvasive, and portable monitoring of changes in blood oxygenation and blood volume related to human brain function. Over the last decade, studies in the laboratory have established that fNIR spectroscopy provides a veridical measure of oxygenation and blood flow in the brain. Our recent findings indicate that fNIR can effectively monitor cognitive tasks such as attention, working memory, target categorization, and problem solving. These experimental outcomes compare favorably with functional magnetic resonance imaging (fMRI) studies, and in particular, with the blood oxygenation level dependent signal. Since fNIR can be implemented in the form of a wearable and minimally intrusive device, it has the capacity to monitor brain activity under real life conditions and in everyday environments. Moreover, the fNIR system is amenable to integration with other established physiological and neurobehavioral measures, including electroencephalogram, eye tracking, pupil reflex, heart rate variability, respiration, and electrodermal activity.     

Analytical characterization of heat transport through biological media incorporating hyperthermia treatment

Modeling and understanding heat transport and temperature variations within biological tissues and body organs are key issues in medical thermal therapeutic applications, such as hyperthermia cancer treatment. The biological media can be treated as a blood saturated tissue represented by a porous matrix. A comprehensive analytical investigation of bioheat transport through the tissue/organ is carried out including thermal conduction in tissue and vascular system, blood–tissue convective heat exchange, metabolic heat generation and imposed heat flux. Utilizing local thermal non-equilibrium model in porous media theory, exact solutions for blood and tissue phase temperature profiles as well as overall heat exchange correlations are established for the first time, for two primary tissue/organ models representing isolated and uniform temperature conditions, while incorporating the pertinent effective parameters, such as volume fraction of the vascular space, ratio of the blood and the tissue matrix thermal conductivities, interfacial blood–tissue heat exchange, tissue/organ depth, arterial flow rate and temperature, body core temperature, imposed hyperthermia heat flux, metabolic heat generation, and blood physical properties. A simplified solution based on the local thermal equilibrium between the tissue and the blood is also presented.     

Application of a generic bow-tie based risk analysis framework on risk management of sea ports and offshore terminals

Ports and offshore terminals are critical infrastructure resources and play key roles in the transportation of goods and people. With more than 80 percent of international trade by volume being carried out by sea, ports and offshore terminals are vital for seaborne trade and international commerce. Furthermore in today's uncertain and complex environment there is a need to analyse the participated risk factors in order to prioritise protective measures in these critically logistics infrastructures. As a result of this study is carried out to support the risk assessment phase of the proposed Risk Management (RM) framework used for the purpose of sea ports and offshore terminals operations and management (PTOM). This has been fulfilled by integration of a generic bow-tie based risk analysis framework into the risk assessment phase as a backbone of the phase. For this reason Fault Tree Analysis (FTA) and Event Tree Analysis (ETA) are used to analyse the risk factors associated within the PTOM. This process will eventually help the port professionals and port risk managers to investigate the identified risk factors more in detail. In order to deal with vagueness of the data Fuzzy Set Theory (FST) and possibility approach are used to overcome the disadvantages of the conventional probability based approaches.     

Spray drying microencapsulation of natural canthaxantin using soluble soybean polysaccharide as a carrier

Microencapsulation of canthaxanthin produced by Dietzia natronolimnaea HS-1 using soluble soybean polysaccharide (SSPS) as a wall material by spray drying method was studied. The SSPS showed very good ability for microencapsulation of canthaxanthin due to its emulsifying properties. The effects of the ratios of core to wall on characteristics of microcapsules were investigated at ratios of 0.25, 0.50, 0.75, and 1.00. The best ratio of core to wall was 0.25 because the microcapsules prepared with this ratio had the smallest size in droplets (0.78 μm) and microcapsules (7.94 μm), also they had the highest microencapsulation efficiency (90.1%) and the lowest losing during process (10.3%). The stability of microcapsules was examined at 25°C in light and dark during 16 weeks of storage. The degradation of canthaxanthin was more retarded by microencapsulation and greater canthaxanthin stability was observed in dark than light condition. The results showed the oxidation was more suppressed for the microcapsules prepared from the emulsion having smaller droplets.     

Ti‐Doping to Reduce Conductivity in Bi0.85Nd0.15FeO3 Ceramics

In 2009, Karimi et al. reported that Bi_1‐xNd_xFeO₃ 0.15 ≤ x ≤ 0.25 exhibited a PbZrO₃ (PZ)‐like structure. These authors presented some preliminary electrical data for the PZ‐like composition but noted that the conductivity was too high to obtain radio‐frequency measurements representative of the intrinsic properties. In this study, Bi_0.85Nd_0.15Fe_1‐yTi_yO₃ (0 ≤ y ≤ 0.1) were investigated, in which Ti acted as a donor dopant on the B‐site. In contrast to the original study of Karimi et al., X‐ray diffraction (XRD) of Bi_0.85Nd_0.15FeO₃ revealed peaks which were attributed to a mixture of PZ‐like and rhombohedral structures. However, as the Ti (0 < y ≤ 0.05) concentration increased, the rhombohedral peaks disappeared and all intensities were attributed to the PZ‐like phase. For y = 0.1, broad XRD peaks indicated a significant decrease in effective diffracting volume. Electron diffraction confirmed that the PZ‐like phase was dominant for y ≤ 0.05, but for y = 0.1, an incommensurate structure was present, consistent with the broadened XRD peaks. The substitution of Fe³⁺ by Ti⁴⁺ decreased the dielectric loss at room temperature from >0.3 to <0.04 for all doped compositions, with a minimum (0.015) observed for y = 0.03. The decrease in dielectric loss was accompanied by a decrease in the room temperature bulk conductivity from ～1 mS cm^?1 to <1 μS cm^?1 and an increase in bulk activation energy from 0.29 to >1 eV. Plots of permittivity (?_r) versus temperature for 0.01 ≤ y ≤ 0.05 revealed a step rather than a peak in ?_r on heating at the same temperature determined for the antiferroelectric–paraelectric phase transition by differential scanning calorimetry. Finally, large electric fields were applied to all doped samples which resulted in a linear dependence of polarisation on the electric field similar to that obtained for PbZrO₃ ceramics under equivalent experimental conditions.     

Gain stabilization in a quantum‐dot semiconductor optical amplifier using tapered waveguide structure

In this paper, transient gain of a quantum‐dot semiconductor optical amplifier (QD‐SOA) is studied. Waveguide of the QD‐SOA is considered to have a tapered structure in which width of the waveguide increases along the QD‐SOA. It is observed that by employing tapered waveguide, gain as the key feature of the device acquires more stability, investigated by studying the impact of a powerful optical pulse on the gain as it passes through the amplifier. Thus, by gradually increasing the width of the waveguide along QD‐SOA active region, drop in the gain, caused by the strong pulse, decreases. Transient gain of the device is obtained for several outputs to input width ratios. It is demonstrated that as the width ratio increases, gain stability improves drastically; as for width ratio of 10, stability increases over 10 times compared with the generic QD‐SOA. In addition to the gain, cross‐gain modulation as a nonlinear process, which depends on the gain instability imposed by strong pulses, is studied. In this paper, the rate equations are employed for modeling tapered waveguide QD‐SOA. MATLAB ODE (MathWorks, MA, USA) along with the finite difference method is used for studying and simulating the device. Copyright © 2013 John Wiley & Sons, Ltd.     

High‐responsivity AlGaN–GaN multi‐quantum well UV photodetector

In this paper, we propose a set of AlGaN–GaN multi‐quantum well (MQW) photodetectors based on p‐i‐n heterostructures with 14 AlGaN–GaN MQW structures in i‐region, where GaN quantum well has 6 nm thickness and Al_xGa_1−xN barrier thickness is 3 nm. In this structure, the peak responsivity of 0.19 A/W at 246 nm is reported. In addition, we investigate effects of various parameters on responsivity, and we show that responsivity of MQW‐based photodetectors strongly depends on proper device design, that is, number of quantum wells, well thickness, barrier thickness, and mole fraction. We also show that increasing number of quantum wells, thickness of wells, and mole fraction as well as decreasing thickness of barriers, increase the responsivity. Using obtained results, we proposed optimal structure. Copyright © 2013 John Wiley & Sons, Ltd.     

The study of an interaction of solid particles with various surfaces using TSM sensors

The interaction of solid particles with various surfaces has been experiencing growing interest in many areas of nanotechnology, colloidal science, and biology. In this paper the interactions of solid particles with the surface of piezoelectric thickness shear mode (TSM) sensors have been studied. A mechanical model has been presented to evaluate the effect of particle loading on the behavior of a TSM sensor. The main sources contributing to the interaction, such as Van der Waals force, friction force, and electrostatic force, are discussed. Experiments have been designed for 10-100 microm particles on the 5-MHz and 10-MHz TSM sensors. It has been shown that the resonant frequencies of the TSM sensors might increase or decrease depending on the interaction conditions. The results have shown that the TSM sensor technique could provide the information on the mass/size of a particle and the binding energy between a particle and the sensor surface. This technique may find its applications in characterizing the properties of an interaction between particles and various surfaces.     

Cooperative lattice coding and decoding in half-duplex channels

We propose novel lattice coding/decoding schemes for half-duplex outage-limited cooperative channels. These schemes are inspired by the cooperation protocols of Azarian et al. and enjoy an excellent performance-complexity tradeoff. More specifically, for the. relay channel, we first use our lattice coding framework to generalize Yang and Belfiore implementation of the non-orthogonal amplify and forward cooperation protocol. This generalization is shown to offer significant performance gains while keeping the decoding complexity manageable. We then devise a novel variant of the dynamic decode and forward protocol, along with a lattice-coded implementation, which enjoys a near-optimal diversity-multiplexing tradeoff with a low encoding/decoding complexity. Finally, for the cooperative multiple-access channel, we present a lattice-coded implementation of the non-orthogonal amplify and forward protocol and demonstrate its excellent performance-complexity tradeoff. Throughout the paper, we establish the performance gains of our proposed protocols via a comprehensive simulation study