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Energy Loss Rate Of A Charged Particle In Hgte/(Hgte, Cdte) Quantum Wells, Qinjun Chen, Yee Sin Ang, Xiaolin Wang, R A. Lewis, Chao Zhang Jan 2015

Energy Loss Rate Of A Charged Particle In Hgte/(Hgte, Cdte) Quantum Wells, Qinjun Chen, Yee Sin Ang, Xiaolin Wang, R A. Lewis, Chao Zhang

Yee Sin Ang

The energy loss rate (ELR) of a charged particle in a HgTe/(HgTe, CdTe) quantum well is investigated. We consider scattering of a charged particle by the bulk insulating states in this type of topological insulator. It is found that the ELR characteristics due to the intraband excitation have a linear energy dependence while those due to interband excitation depend on the energy exponentially. An interesting quantitative result is that for a large range of the incident energy, the mean inelastic scattering rate is around a few terahertz.


Chiral-Like Tunneling Of Electrons In Two-Dimensional Semiconductors With Rashba Spin-Orbit Coupling, Yee Sin Ang, Zhongshui Ma, C Zhang Jan 2015

Chiral-Like Tunneling Of Electrons In Two-Dimensional Semiconductors With Rashba Spin-Orbit Coupling, Yee Sin Ang, Zhongshui Ma, C Zhang

Yee Sin Ang

The unusual tunneling effects of massless chiral fermions (mCF) and massive chiral fermions (MCF) in a single layer graphene and bilayer graphene represent some of the most bizarre quantum transport phenomena in condensed matter system. Here we show that in a two-dimensional semiconductor with Rashba spin-orbit coupling (R2DEG), the real-spin chiral-like tunneling of electrons at normal incidence simultaneously exhibits features of mCF and MCF. The parabolic branch of opposite spin in R2DEG crosses at a Dirac-like point and has a band turning point. These features generate transport properties not found in usual two-dimensional electron gas. Albeit its p Berry phase, …


Intraband Nonlinear Terahertz Waves Absorption Of Gapped Graphene, Asya Tawfiq, Yee Sin Ang, Chao Zhang Jan 2015

Intraband Nonlinear Terahertz Waves Absorption Of Gapped Graphene, Asya Tawfiq, Yee Sin Ang, Chao Zhang

Yee Sin Ang

The effect of bandgap opening on the intraband nonlinear optical response of graphene in terahertz frequency regime is theoretically investigated. The nonlinear optical response of gapped graphene is found to be sensitively influenced by the bandgap level and temperature. © 2012 IEEE.


Nonlinear Optical Spectrum Of Two-Dimensional Electron Gas With Rashba Spin-Orbit Interaction In Thz Frequency Regime, Yee Sin Ang, C Zhang, Qinjun Chen Jan 2015

Nonlinear Optical Spectrum Of Two-Dimensional Electron Gas With Rashba Spin-Orbit Interaction In Thz Frequency Regime, Yee Sin Ang, C Zhang, Qinjun Chen

Yee Sin Ang

We theoretically calculate the nonlinear optical spectrum of two-dimensional electron gas in the presence of Rashba spin-orbit interaction in terahertz frequency regime. For Rashba coupling parameter in the order of 0.4 eVÅ, the nonlinear optical response exceeds the linear response with the application of an external electric field strength in the order of 103 V/cm.


Nonlinear Optical Response Of Graphene Superlattice In Terahertz Frequency Regime, Yee Sin Ang, Chao Zhang Jan 2015

Nonlinear Optical Response Of Graphene Superlattice In Terahertz Frequency Regime, Yee Sin Ang, Chao Zhang

Yee Sin Ang

We investigate the nonlinear optical response of a Kronig-Penney type graphene superlattice in which the Fermi velocity of the massless Dirac quasiparticle anisotropically depends on the direction of propagation. Such velocity anisotropy results in enhanced nonlinear optical response in terahertz frequency regime.


Review Of Four Novel Dosimeters Developed For Use In Radiotherapy, P Metcalfe, A Quinn, K Loo, M Lerch, M Petasecca, J Wong, N Hardcastle, M Carolan, J Mcnamara, D Cutajar, I Fuduli, A Espinoza, C Porumb, Anatoly Rosenfeld Jan 2015

Review Of Four Novel Dosimeters Developed For Use In Radiotherapy, P Metcalfe, A Quinn, K Loo, M Lerch, M Petasecca, J Wong, N Hardcastle, M Carolan, J Mcnamara, D Cutajar, I Fuduli, A Espinoza, C Porumb, Anatoly Rosenfeld

Anthony A Espinoza Mr

Centre for Medical Radiation Physics (CMRP) is a research strength at the University of Wollongong, the main research theme of this centre is to develop prototype novel radiation dosimeters. Multiple detector systems have been developed by Prof Rosenfelds’ group for various radiation detector applications. This paper focuses on four current detector systems being developed and studied at CMRP. Two silicon array detectors include the magic plate and dose magnifying glass (DMG), the primary focus of these two detectors is high spatial and temporal resolution dosimetry in intensity modulated radiation therapy (IMRT) beams. The third detector discussed is the MOSkin which …


A Two Dimensional Silicon Detectors Array For Quality Assurance In Stereotactic Radiotherapy: Magicplate-512, A Aldosari, M Petasecca, A Espinoza, M Newall, I Fuduli, C Porumb, S Alshaikh, Z Alrowaili, M Weaver, P Metcalfe, M Carolan, M. Lerch, V Perevertaylo, A Rosenfeld Jan 2015

A Two Dimensional Silicon Detectors Array For Quality Assurance In Stereotactic Radiotherapy: Magicplate-512, A Aldosari, M Petasecca, A Espinoza, M Newall, I Fuduli, C Porumb, S Alshaikh, Z Alrowaili, M Weaver, P Metcalfe, M Carolan, M. Lerch, V Perevertaylo, A Rosenfeld

Anthony A Espinoza Mr

Purpose: Silicon diode arrays are commonly implemented in radiation therapy quality assurance applications as they have a number of advantages including: real time operation (compared to the film) and high spatial resolution, large dynamic range and small size (compared to ionizing chambers). Most diode arrays have detector pitch that is too coarse for routine use in small field applications. The goal of this work is to characterize the two-dimensional monolithic silicon diode array named "MagicPlate-512" (MP512) designed for QA in stereotactic body radiation therapy (SBRT) and stereotactic radio surgery (SRS). Methods: MP512 is a silicon monolithic detector manufactured on a …


A Comparative Analysis Of Multichannel Data Acquisition Systems For Quality Assurance In External Beam Radiation Therapy, Iolanda Fuduli, Claudiu Porumb, Anthony Espinoza, Abdullah Aldosari, Martin Carolan, Michael Lf Lerch, Peter E. Metcalfe, Anatoly Rosenfeld, Marco Petasecca Jan 2015

A Comparative Analysis Of Multichannel Data Acquisition Systems For Quality Assurance In External Beam Radiation Therapy, Iolanda Fuduli, Claudiu Porumb, Anthony Espinoza, Abdullah Aldosari, Martin Carolan, Michael Lf Lerch, Peter E. Metcalfe, Anatoly Rosenfeld, Marco Petasecca

Anthony A Espinoza Mr

The paper presents a comparative study performed by the Centre of Medical Radiation Physics (CMRP) on three multichannel Data Acquisition Systems (DAQ) based on different analogue front-ends to suit a wide range of radiotherapy applications. The three front-ends are: a charge-to-frequency converter developed by INFN Torino, an electrometer and a charge-to-digital converter (both commercial devices from Texas Instruments). For the first two (named DAQ A and B), the CMRP has designed the read-out systems whilst the third one (DAQ C) comes with its own evaluation board. For the purpose of the characterization DAQ A and DAQ B have been equipped …


The Feasibility Study And Characterziation Of A Two-Dimensional Diode Array In “Magic Phantom” For High Dose Rate Brachytherapy Quality Assurance, A Espinoza, B Beeksma, M Petasecca, I Fuduli, C Porumb, D L. Cutajar, S Corde, M A. Jackson, M Lf Lerch, Anatoly B. Rosenfeld Jan 2015

The Feasibility Study And Characterziation Of A Two-Dimensional Diode Array In “Magic Phantom” For High Dose Rate Brachytherapy Quality Assurance, A Espinoza, B Beeksma, M Petasecca, I Fuduli, C Porumb, D L. Cutajar, S Corde, M A. Jackson, M Lf Lerch, Anatoly B. Rosenfeld

Anthony A Espinoza Mr

High dose rate (HDR) brachytherapy is a radiation treatment technique capable of delivering large dose rates to the tumor. Radiation is delivered using remote afterloaders to drive highly active sources (commonly 192Ir with an air KERMA strength range between 20 000 and 40 000 U, where 1 U = 1 uGy m2/h in air) through applicators directly into the patient's prescribed region of treatment. Due to the obvious ramifications of incorrect treatment while using such an active source, it is essential that there are methods for quality assurance (QA) that can directly and accurately verify the treatment plan and the …


Characterization Of An Innovative P-Type Epitaxial Diode For Dosimetry In Modern External Beam Radiotherapy, A Aldosari, A Espinoza, D Robinson, I Fuduli, C Porumb, S Alshaikh, M Carolan, M Lerch, V Perevertaylo, Anatoly Rosenfeld, M Petasecca Jan 2015

Characterization Of An Innovative P-Type Epitaxial Diode For Dosimetry In Modern External Beam Radiotherapy, A Aldosari, A Espinoza, D Robinson, I Fuduli, C Porumb, S Alshaikh, M Carolan, M Lerch, V Perevertaylo, Anatoly Rosenfeld, M Petasecca

Anthony A Espinoza Mr

Due to the ever-increasing complexity of treatment modalities in radiation therapy, there has been a greater need for detectors to perform quality assurance to ensure patients are treated correctly and safely. Modern radiation therapy techniques involve small field sizes, high dose gradients, and varying intensity of energy and rate. The ideal dosimeter for this treatment should display high spatial resolution, high linearity, accuracy, and radiation hardness. Silicon detectors have been widely used for radiotherapy measurements and have many attractive qualities as a dosimeter; weaknesses of silicon detectors are, however, decreases in sensitivity with accumulated dose. The Centre for Medical Radiation …


X-Tream: A Novel Dosimetry System For Synchrotron Microbeam Radiation Therapy, M Petasecca, A Cullen, I Fuduli, A Espinoza, C Porumb, C Stanton, A H. Aldosari, E Brauer-Krisch, H Requardt, A Bravin, V Perevertaylo, Anatoly B. Rosenfeld, M L. F Lerch Jan 2015

X-Tream: A Novel Dosimetry System For Synchrotron Microbeam Radiation Therapy, M Petasecca, A Cullen, I Fuduli, A Espinoza, C Porumb, C Stanton, A H. Aldosari, E Brauer-Krisch, H Requardt, A Bravin, V Perevertaylo, Anatoly B. Rosenfeld, M L. F Lerch

Anthony A Espinoza Mr

Microbeam Radiation Therapy (MRT) is a radiation treatment technique under development for inoperable brain tumors. MRT is based on the use of a synchrotron generated X-ray beam with an extremely high dose rate ( ~ 20 kGy/sec), striated into an array of X-ray micro-blades. In order to advance to clinical trials, a real-time dosimeter with excellent spatial resolution must be developed for absolute dosimetry. The design of a real-time dosimeter for such a radiation scenario represents a significant challenge due to the high photon flux and vertically striated radiation field, leading to very steep lateral dose gradients. This article analyses …


Multichannel Data Acquisition System Comparison For Quality Assurance In External Beam Radiation Therapy, I Fuduli, M Newall, A Espinoza, C Porumb, M Carolan, M. Lerch, P Metcalfe, A Rosenfeld, M Petasecca Jan 2015

Multichannel Data Acquisition System Comparison For Quality Assurance In External Beam Radiation Therapy, I Fuduli, M Newall, A Espinoza, C Porumb, M Carolan, M. Lerch, P Metcalfe, A Rosenfeld, M Petasecca

Anthony A Espinoza Mr

Megavoltage photon radiation therapies are widely used in modern cancer treatment. The improvement of the treatment has lead to the need of Quality Assurance (QA) devices to detect malfunctioning or human mistakes during the planning phase and treatment verification. Active electronic devices for 2D or 3D QA in external beam radiotherapy are typically based on analogue/digital mixed signal Data Acquisition Systems (DAS) which are required to have high spatial resolution, large dynamic range, high sensitivity, large numbers of channels and fast real-time capabilities. The Centre of Medical Radiation Physics (CMRP) has developed several multichannel DAS architectures based on different analogue …


Optimal Energy For Cell Radiosensitivity Enhancement By Gold Nanoparticles Using Synchrotron-Based Monoenergetic Photon Beams, Wan Nordiana Rahman, Stephanie Corde, Naoto Yagi, Siti Aishah Abdul Aziz, Nathan Annabell, Moshi Geso Jan 2015

Optimal Energy For Cell Radiosensitivity Enhancement By Gold Nanoparticles Using Synchrotron-Based Monoenergetic Photon Beams, Wan Nordiana Rahman, Stephanie Corde, Naoto Yagi, Siti Aishah Abdul Aziz, Nathan Annabell, Moshi Geso

Stéphanie Corde

Gold nanoparticles have been shown to enhance radiation doses delivered to biological targets due to the high absorption coefficient of gold atoms, stemming from their high atomic number (Z) and physical density. These properties significantly increase the likelihood of photoelectric effects and Compton scattering interactions. Gold nanoparticles are a novel radiosensitizing agent that can potentially be used to increase the effectiveness of current radiation therapy techniques and improve the diagnosis and treatment of cancer. However, the optimum radiosensitization effect of gold nanoparticles is strongly dependent on photon energy, which theoretically is predicted to occur in the kilovoltage range of energy. …


Depth Image Super-Resolution Using Multi-Dictionary Sparse Representation, Haoheng Zheng, Abdesselam Bouzerdoum, Son Lam Phung Jan 2015

Depth Image Super-Resolution Using Multi-Dictionary Sparse Representation, Haoheng Zheng, Abdesselam Bouzerdoum, Son Lam Phung

Haoheng Zheng

In this paper, we propose a new depth super-resolution technique based on multiple dictionary learning. A novel dictionary selection method using basis pursuit is proposed to generate multiple dictionaries adaptively. A sparse representation of each low-resolution input patch is derived based on the learned dictionaries, and then used to reconstruct the corresponding high-resolution patch. Experimental results are presented which show that the proposed multi-dictionary scheme outperforms existing depth super-resolution methods.


Book Review, Earthea Nance Dec 2014

Book Review, Earthea Nance

Earthea Nance, PhD (Stanford University, 2004)

Book Review published in the journal Water International (2015) The topic… “The book builds upon Nance’s research and presents a comprehensive account of Brazil’s experience of implementing condominial sewerage.” The topic… “From the very beginning, the author expresses her concerns in escaping from preconceived ideas about conventional and participatory development, positioning her views within a third wave of post-structural development discourse, neither universalist nor relativist, that is neither denying nor overvaluing the social content of development.” Research methods… “Nance manages to do so by integrating different areas of established knowledge and examining her research issue from a privileged historical perspective. …