The Impact of Therapeutic Interventions on Quality of Life in the Periodontitis Patient

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Flow velocity mapping using contrast enhanced high-frame-rate plane wave ultrasound and image tracking: methods and initial in vitro and in vivo evaluation

Ultrasound imaging is the most widely used method for visualising and quantifying blood flow in medical practice, but existing techniques have various limitations in terms of imaging sensitivity, field of view, flow angle dependence, and imaging depth. In this study, we developed an ultrasound imaging velocimetry approach capable of visualising and quantifying dynamic flow, by combining high-frame-rate plane wave ultrasound imaging, microbubble contrast agents, pulse inversion contrast imaging and speckle image tracking algorithms. The system was initially evaluated in vitro on both straight and carotid-mimicking vessels with steady and pulsatile flows and in vivo in the rabbit aorta. Colour and spectral Doppler measurements were also made. Initial flow mapping results were compared with theoretical prediction and reference Doppler measurements and indicate the potential of the new system as a highly sensitive, accurate, angle-independent and full field-of-view velocity mapping tool capable of tracking and quantifying fast and dynamic flows

Relay beamforming to mitigate inter-relay interference in multi-cell scenario

In relay assisted Long Term Evolution-Advanced (LTE-A) network, enhanced Node B (eNB) autonomously selects different backhaul sub-frame configurations to adopt traffic variations, which might cause inter-relay interference (IRI) between relay nodes (RNs) in adjacent cells. IRI can happen due to asynchronous transmission between adjacent cells, which results in IRI from the access link to the backhaul link of adjacent relay in the downlink direction and vice versa. This causes severe loss in system capacity and introduces high outage probability. In this article, we consider the IRI problem in a multi-cell relaying system. Previous studies consider the beamforming design for cooperative relay network as a single-cell problem, without taking into account the occurrence of IRI. However, the performance of the RN assisted network is limited by the IRI from adjacent RN. A hybrid zero-forcing and singular value decomposition (ZF-SVD) beamforming technique is proposed to eliminate the IRI. Simulation results show that the proposed scheme out-performs the comparable scheme in both the ergodic capacity and outage probability

Measurement of flow volume in the presence of reverse flow with ultrasound speckle decorrelation

Direct measurement of volumetric flow rate in the cardiovascular system with ultrasound is valuable but has been a challenge because most current 2-D flow imaging techniques are only able to estimate the flow velocity in the scanning plane (in-plane). Our recent study demonstrated that high frame rate contrast ultrasound and speckle decorrelation (SDC) can be used to accurately measure the speed of flow going through the scanning plane (through-plane). The volumetric flow could then be calculated by integrating over the luminal area, when the blood vessel was scanned from the transverse view. However, a key disadvantage of this SDC method is that it cannot distinguish the direction of the through-plane flow, which limited its applications to blood vessels with unidirectional flow. Physiologic flow in the cardiovascular system could be bidirectional due to its pulsatility, geometric features, or under pathologic situations. In this study, we proposed a method to distinguish the through-plane flow direction by inspecting the flow within the scanning plane from a tilted transverse view. This method was tested on computer simulations and experimental flow phantoms. It was found that the proposed method could detect flow direction and improved the estimation of the flow volume, reducing the overestimation from over 100% to less than 15% when there was flow reversal. This method showed significant improvement over the current SDC method in volume flow estimation and can be applied to a wider range of clinical applications where bidirectional flow exists

Using amplify-and-forward relay for coverage extension in indoor environments

Cooperative communication is a promising method for increasing the capacity and extending the coverage between a base station (BS) and a mobile user (MU) by using relays to exploit cooperative diversity. However, the existing literature mainly focuses on theoretical performance evaluation without experimental validation and, thus, fails to address the effects on real-world radio signal propagation. This research, therefore, aims to develop a prototype amplify-and-forward (AF) relay using software-defined radio (SDR) to evaluate the real-world performance of such a relay in improving coverage. The proposed relay is developed using the LabVIEW software and programmed on a National Instruments-Universal Software Radio Peripheral 2922 (NI-USRP 2922) SDR platform. The major merit of this entire communication setup is less expensive as the system uses a reprogrammable hardware. The measurements are performed indoors, and the signal strength or received power at the MU in cases with and without the relay is recorded. The results show that the received power performance and signal-to-noise ratio (SNR) at the user improve significantly when the AF relay is deployed compared to when direct link point-to-point transmission without the relay is used

Characterization of Electromagnetic Valveless Micropump

This paper presents an electromagnetically-actuated micropump for microfluidic application. The system comprises two modules; an electromagnetic actuator module and a diffuser module. Fabrication of the diffuser module can be achieved using photolithography process with a master template and a PDMS prepolymer as the structural material. The actuator module consists of two power inductors and two NdFeB permanent magnets placed between the diffuser elements. The choice of this actuation principle merits from low operating voltage (1.5 Vdc) and the flow direction can be controlled by changing the orientation of the magnet vibration. Maximum volumetric flow rate of the fabricated device at zero backpressure is 0.9756 µLs-1 and 0.4659 µLs-1 at the hydrostatic backpressure of 10 mmH2O at 9 Hz of switching speed

The effect of carbon sources on the expression level of thermostable L2 lipase in Pichia pastoris

Thermostable lipases are enzymes that are particularly pleasing for industrial purposes such as in the production of detergents, animal skin-based industry and food processing endeavours. Thermostable L2 lipase gene fished out from Bacillus sp. L2 was cloned into Pichia pastoris strain GS115 under constitutive expression system of pGAPZαA. Study performed on various carbon sources revealed that glucose and glycerol support the growth of Pichia pastoris and expression of L2 lipase. In addition, the by-product of sugar refinery processes (molasses) was found to be a potential carbon source for the growth of P. pastoris and L2 lipase expression. Since the thermostable L2 lipase will be extracellularly secreted into the medium, the use of P. pastoris expression system is seen as an alternative to the conventional expression system of Escherichia coli that applies intracellular expression of the L2 lipase gene encoded.Key words: Thermostable lipase, Pichia pastoris, constitutive expression, carbon source

Investigation of the Effect Temperature on Photovoltaic (PV) Panel Output Performance

The main limit of PV systems is the low conversion efficiency of PV panels, which is strongly influenced by their operating temperature. Lack of accuracy in consideration through PV panel temperature increases the financial risk of system installation. This present study investigates the effects of operating temperature on monocrystalline PV panel at Perlis, Malaysia. A selected model of PV panel firstly was simulated using PVSYST software in order to evaluate its output performance. Meanwhile, PROVA 200 used to measure and record all electrical data for outdoor experimental during the sunniest day. Besides, the thermal distribution was analysed through PV panel temperatures and thermal imaging. Simulation results implied that the output power of PV panel decreases with increasing of its working temperature followed by the efficiency. The experimental results obviously show that the STC parameters do not represent the real operating conditions of PV panel for outdoor conditions. Less output power was produced affected by the atmospheric factors such as solar irradiance and ambient temperature. These both factors strongly affected the PV panel temperature distribution. In short, the elevating of PV panel temperature contributed to the negative impact on output performance of the panel

Temperature Distribution of Three-Dimensional Photovoltaic Panel by Using Finite Element Simulation

The low electricity performance of a photovoltaic (PV) panel has been concerned in the PV application system. The effect of environmental and operating condition was affected the performance of the PV panel. In this research work, the main objective is to perform a three-dimensional geometry model of monocrystalline silicon PV panel with and without cooling system by using finite element method. In the case of a cooling system, the effect of the Direct Current (DC) fan flow rate on the temperature distribution of PV panel was investigated. The electrical behaviour of this PV panel is obtained based on the average temperature of the PV panel obtained and average solar irradiance from site location. According to the experimental results, PV panel with cooling system can be significant to provide better performance than the PV panel without cooling system in the same environmental condition. For the effect of flow rate of DC fan in the PV panel with cooling system, the performance of this PV panel has been improved as increasing in flow rate of DC fan