Hanh Le - Academia.edu (original) (raw)

Papers by Hanh Le

Organizational Research Methods, 2007

Measurement artifacts, including measurement errors and scale-specific factors, distort observed ... more Measurement artifacts, including measurement errors and scale-specific factors, distort observed correlations between measures of psychological and organizational constructs. The authors discuss two alternative procedures, one using the generalized coefficient of equivalence and stability (GCES) and one based on structural equation modeling, to correct for the biasing effect of measurement artifacts in order to estimate construct-level relationships. Assumptions underlying the procedures are discussed and the degrees of biases resulting from violating the assumptions are examined by means of Monte Carlo simulation. They then propose an approach using cumulative knowledge in the literature about properties of measures of a construct to estimate the GCES. That approach can allow researchers to estimate relationships between constructs in most research situations. The authors apply the approach to estimate the GCES for overall job satisfaction, an important organizational construct.

Breast cancer cells from patients hold an important role in antigen production for immunotherapy,... more Breast cancer cells from patients hold an important role in antigen production for immunotherapy, drug testing, and cancer stem cell studies. To date, although many studies have been conducted to develop protocols for the isolation and culture of breast cancer cells from tumour biopsies, the efficiencies of these protocols remain low. This study aimed to identify a suitable medium for the isolation and propagation of primary breast cancer cells from breast tumour biopsies. Breast tumour biopsies were obtained from hospitals after all patients had given their written informed consent and were cultured according to the expanding tumour method in 3 different media: DMEM/F12 (Dulbecco's Modified Eagle Medium: Nutrient Mixture F-12) supplemented with 10% FBS (Fetal bovine serum) and 1% antibiotic-antimycotic (Medium D); Medium 171 supplemented with 1X MEGS (Mammary Epithelial Growth Supplement) and 1% antibiotic-antimycotic (Medium M); or a 1:1 mixture of Medium D and Medium M (Mediu...

Journal of biomedical optics, 2018

This paper reports the development and system analysis of a laparoscopic system based on structur... more This paper reports the development and system analysis of a laparoscopic system based on structured illumination technique capable of three-dimensional (3-D) reconstruction of porcine intestine during surgical anastomosis (connection of tubular structures). A calibration target is used to validate the system performance and results show a depth of field of 20 mm with an accuracy of 0.008 mm and precision of 0.25 mm. The imaging system is used to reconstruct a quantitative 3-D depth measurement of ex vivo porcine bowel tissues to mimic an end-to-end bowel anastomosis scenario. We demonstrate that the system can detect a suture in the tissue and map homogeneous surfaces of the intestine with different tissue pigments, affirming the feasibility for depth quantization for guiding and assisting medical diagnostic decisions in anastomosis surgery.

Chinese Optics Letters, 2017

An endoscopic imaging system using a plenoptic technique to reconstruct 3-D information is demons... more An endoscopic imaging system using a plenoptic technique to reconstruct 3-D information is demonstrated and analyzed in this Letter. The proposed setup integrates a clinical surgical endoscope with a plenoptic camera to achieve a depth accuracy error of about 1 mm and a precision error of about 2 mm, within a 25 mm × 25 mm field of view, operating at 11 frames per second.

OncoTargets and Therapy, 2016

Background: Breast cancer (BC) is one of the leading cancers in women. Recent progress has enable... more Background: Breast cancer (BC) is one of the leading cancers in women. Recent progress has enabled BC to be cured with high efficiency. However, late detection or metastatic disease often renders the disease untreatable. Additionally, relapse is the main cause of death in BC patients. Breast cancer stem cells (BCSCs) are considered to cause the development of BC and are thought to be responsible for metastasis and relapse. This study aimed to target BCSCs using dendritic cells (DCs) to treat tumor-bearing humanized mice models. Materials and methods: NOD/SCID mice were used to produce the humanized mice by transplantation of human hematopoietic stem cells. Human BCSCs were injected into the mammary fat pad to produce BC humanized mice. Both hematopoietic stem cells and DCs were isolated from the human umbilical cord blood, and immature DCs were produced from cultured mononuclear cells. DCs were matured by BCSC-derived antigen incubation for 48 hours. Mature DCs were vaccinated to BC humanized mice with a dose of 10 6 cells/mice, and the survival percentage was monitored in both treated and untreated groups. Results: The results showed that DC vaccination could target BCSCs and reduce the tumor size and prolong survival. Conclusion: These results suggested that targeting BCSCs with DCs is a promising therapy for BC.

The views expressed herein are those of the authors and do not necessarily reflect the views of t... more The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peerreviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.

Journal of biomedical optics, 2015

Intestinal anastomosis is a surgical procedure that restores bowel continuity after surgical rese... more Intestinal anastomosis is a surgical procedure that restores bowel continuity after surgical resection to treat intestinal malignancy, inflammation, or obstruction. Despite the routine nature of intestinal anastomosis procedures, the rate of complications is high. Standard visual inspection cannot distinguish the tissue subsurface and small changes in spectral characteristics of the tissue, so existing tissue anastomosis techniques that rely on human vision to guide suturing could lead to problems such as bleeding and leakage from suturing sites. We present a proof-of-concept study using a portable multispectral imaging (MSI) platform for tissue characterization and preoperative surgical planning in intestinal anastomosis. The platform is composed of a fiber ring light-guided MSI system coupled with polarizers and image analysis software. The system is tested on ex vivo porcine intestine tissue, and we demonstrate the feasibility of identifying optimal regions for suture placement.

2000 IEEE International Integrated Reliability Workshop Final Report (Cat. No.00TH8515)

As VLSI technologies are scaled into the deep submicron region, traditional hot-carrier reliabili... more As VLSI technologies are scaled into the deep submicron region, traditional hot-carrier reliability criteria can no longer be satisfied. A more realistic reliability criteria based on circuit performance, that takes into account both the physics of the degradation as well as its impact on device and circuit performance, is necessary. The current method of assessing hot-carrier reliability through simulation is an ad hoc approach, requires extensive tool calibration and yields no insights to the problem at hand. This study proposes a unified approach to evaluating hot-carrier reliability of analog circuits. First, by choosing the appropriate device model that can link device behavior to circuit performance, hot-carrier degradation can be treated as perturbations to device parameters, and therefore, can be correctly reflected at the circuit level. Second, device-level performance parameters (such as I d , gm, and gds) are studied in detail as functions of process parameters VT and J-l. This allows easy prediction of device-level parameter degradation by monitoring just two process parameters. Third, by taking advantage of well-developed circuit-analysis techniques, the small-signal device parameters gm and gds are used as independent variables to Circuit Degradation Models (CDMs), where the degradation of circuitlevel DC parameters of analog sub circuits can be modeled reasonably well as 'perturbations' in VT and J-l. This provides insights into how circuits may behave as various devices within the circuit degrade due to hot-carrier degradation. Finally, by analyzing the analog design space and examining hot-carrier degradation factors that are important to analog circuits, reliability and performance curves are presented as a way for designers and reliability engineers to define a more realistic and circuit-based criteria for hot-carrier degradation.

Biomedical Research and Therapy, 2015

Breast cancer cells from patients hold an important role in antigen production for immunotherapy,... more Breast cancer cells from patients hold an important role in antigen production for immunotherapy, drug testing, and cancer stem cell studies. To date, although many studies have been conducted to develop protocols for the isolation and culture of breast cancer cells from tumour biopsies, the efficiencies of these protocols remain low. This study aimed to identify a suitable medium for the isolation and propagation of primary breast cancer cells from breast tumour biopsies. Breast tumour biopsies were obtained from hospitals after all patients had given their written informed consent and were cultured according to the expanding tumour method in 3 different media: DMEM/F12 (Dulbecco's Modified Eagle Medium: Nutrient Mixture F-12) supplemented with 10% FBS (Fetal bovine serum) and 1% antibiotic-antimycotic (Medium D); Medium 171 supplemented with 1X MEGS (Mammary Epithelial Growth Supplement) and 1% antibiotic-antimycotic (Medium M); or a 1:1 mixture of Medium D and Medium M (Medium DB). The cell culture efficiency was evaluated by several criteria, including the time of cell appearance, cell morphology, capability of proliferation, cell surface marker expression, ALDH (Aldehyde dehydrogenases) activity, karyotype, and tumour formation capacity in immune-deficient mice. Notably, primary cancer cells cultured in Medium DB showed a high expression of breast cancer stem cell surface markers (including CD44 + CD24and CD49f +), low expression of stromal cell surface markers (CD90), high ALDH activity, an abnormal karyotype, and high tumour formation capacity in immune-deficient mice. These findings suggested that Medium DB was suitable to support the survival and proliferation of primary breast cancer cells as well as to enrich breast cancer stem cells.

2013 UKSim 15th International Conference on Computer Modelling and Simulation, 2013

The growth of mobile computing is changing the way people communicate. Mobile devices, especially... more The growth of mobile computing is changing the way people communicate. Mobile devices, especially mobile phones, have become cheaper and more powerful, and are able to run more applications and provide networking services. Mobile phones use fixed cellular infrastructure like base stations and transmission towers to enable users to share multimedia content and access the Internet anytime, anywhere. However, using telecommunications infrastructure introduces costs. Therefore, one of the solutions is to create impromptu ad hoc networks share information amongst users. Such networks are infrastructureless and organizing themselves, much like mobile ad hoc networks (MANETs). This paper investigates how mobile phones with low power Bluetooth technology can be used to create ad hoc networks that allow them to share information. The mobile phones should be able to organize themselves at the application layer of the Bluetooth protocol stack for multi-hop communication. Routing becomes important in order to achieve efficiency in data communication. Several existing routing protocols were implemented and evaluated for this type of network to determine how efficiently they deliver data and deal with network disruptions like a device moving out of transmission range.

Biomedical Optics Express, 2014

We propose a quantification method called Mapped Average Principal component analysis Score (MAPS... more We propose a quantification method called Mapped Average Principal component analysis Score (MAPS) to enumerate the contamination coverage on common medical device surfaces. The method was adapted from conventional Principal Component Analysis (PCA) on non-overlapped regions of a full frame hyperspectral image to resolve the percentage of contamination from the substrate. The concept was proven by using a controlled contamination sample with artificial test soil and color simulating organic mixture, and was further validated using a bacterial system including biofilm on stainless steel surface. We also validate the results of MAPS with other statistical spectral analysis including Spectral Angle Mapper (SAM). The proposed method provides an alternative quantification method for hyperspectral imaging data, which can be easily implemented by basic PCA analysis.

IEEE Transactions on Very Large Scale Integration (VLSI) Systems, 2015

Integrating multiple power converters on-chip improves energy efficiency of manycore architecture... more Integrating multiple power converters on-chip improves energy efficiency of manycore architectures. Switchedcapacitor (SC) dc-dc converters are compatible with conventional CMOS processes, but traditional implementations suffer from limited conversion efficiency. We propose a dynamic voltage and frequency scaling scheme with SC converters that achieves high converter efficiency by allowing the output voltage to ripple and having the processor core frequency track the ripple. Minimum core energy is achieved by hopping between different converter modes and tuning body-bias voltages. A multicore processor model based on a 28-nm technology shows conversion efficiencies of 90% along with over 25% improvement in the overall chip energy efficiency. Index Terms-Dynamic voltage and frequency scaling (DVFS), multicore processors, switched capacitor (SC). I. INTRODUCTION T HE growing need for energy efficiency while utilizing increased transistor densities has led to the development of manycore architectures. To maximize the energy efficiency of a processor when using dynamic voltage and frequency scaling (DVFS) [1], it is highly desirable to independently control the supply and the clock frequency for each core [2], [3].

2013 Fifth International Conference on Computational Intelligence, Communication Systems and Networks, 2013

We investigate and enhance the protocols that can bring connectivity to isolated village networks... more We investigate and enhance the protocols that can bring connectivity to isolated village networks via multiple data mules. These multiple mules communicate in order to find shorter reliable routes and provide higher probability of message delivery. Using movement traces for multiple data mules for rural-like areas the existing protocols ad hoc on-demand distance vector protocol (AODV) and optimal relay path (ORP) were compared. The results show that a rural route can provide telecommunication between the village networks, furthermore that AODV was more applicable to the network than ORP especially as the number of mules increase. Two enhancement algorithms (data mule inter-communicator (DMI) and ultimate data mule inter-communicator (UDMIC)) were developed using the existing protocols. The first enhancement was DMI that is based on using clustering of data to improve the performance between rural networks. The second enhancement was UDMIC, an adaptive algorithm that examines the situation to select an algorithm to improve performance. This enhancement not only managed to use the best of each protocol but in some cases improved network performance.

2012 26th International Conference on Advanced Information Networking and Applications Workshops, 2012

In this paper, we describe the performance of the B.A.T.M.A.N daemon (Batmand) protocol on an ind... more In this paper, we describe the performance of the B.A.T.M.A.N daemon (Batmand) protocol on an indoor Mesh Potato (MP) testbed. The MPs are small devices used for voice communications over the wireless medium but also supports data. The batmand protocol is designed for ad hoc wireless networks. We measure delay, packet loss in order to understand the MPs network performance. The experiments used packets of varying sizes over multiple hops. We analyze the data to see if the network latency for up to four hops is within the recommended boundaries set by ITU-Recommendation G. 114. We also observe the how the network's performance is affected by the varying packet sizes. Finally the experiments also reveal the common issues found on the wireless medium and also indoor testbeds.

2011 Third International Conference on Intelligent Networking and Collaborative Systems, 2011

In this paper, we describe the performance of the B.A.T.M.A.N advanced (Batman-adv) protocol on a... more In this paper, we describe the performance of the B.A.T.M.A.N advanced (Batman-adv) protocol on an indoor Mesh Potato (MP) testbed. The MPs are small devices used for voice communications over the wireless medium but also supports data. The Batman-adv protocol is designed for ad hoc wireless networks. We measure delay and packet loss, jitter and throughput in order to understand the MPs network performance. The experiments used packets of varying sizes over multiple hops. We analyze the data to see if the network latency for up to four hops is within the recommended boundaries set by ITU-Recommendation G. 114. We also observe the how the network's performance is affected by the varying packet sizes. Finally the experiments also reveal the common issues found on the wireless medium and also indoor testbeds.

2013 Fifth International Conference on Computational Intelligence, Communication Systems and Networks, 2013

The advancement of mobile phones is creating cheaper and more powerful devices that are capable o... more The advancement of mobile phones is creating cheaper and more powerful devices that are capable of providing networking services using readily available technologies embedded on mobile phones. Networking services are usually provided using fixed cellular infrastructure owned by Cellular Network Providers. The use of the cellular infrastructure incurs the cost of data exchange. One way to eliminate costs is to create spontaneous ad hoc networks that allow mobile phone users to connect directly and share information using technologies such as Bluetooth. In order to efficiently share information, routing techniques are needed that efficiently use the resources in these networks. This paper presents the design of a mobile phone ad hoc network and a prototype system that uses established routing algorithms to determine which routing protocols are well suited for such a network.

2012 26th International Conference on Advanced Information Networking and Applications Workshops, 2012

Traditionally data cannot be delivered between isolated networks. However by using a data mule wh... more Traditionally data cannot be delivered between isolated networks. However by using a data mule which is a combination between an electronic device and a mobile entity we can connect isolated networks. However, the main problem is that a long delay is experience and most of the time a large amount of undeliverable. In this paper we propose an algorithm that increases message delivery by clustering data mules in order to find a more reliable path between the sender and the receiver. Instead of data remaining on the same mule when travelling from one network to another, our algorithm allows mules to transfer data to nearby mules arriving to the destination network sooner. Using movement traces for the data mules for rural-like areas we compared two algorithms for a different number of nodes in the network and different communication ranges for each node. The preliminary results show that our proposed algorithm increases the network performance.

2009 International Conference on Network-Based Information Systems, 2009

Page 1. An agent based layered framework to facilitate intelligent Wireless Sensor Networks Hanh ... more Page 1. An agent based layered framework to facilitate intelligent Wireless Sensor Networks Hanh Le Department of Computer Science University of Cape Town Cape Town, South Africa hanh@cs.uct.ac.za André Scholtz Department ...

Biomedical Optics Express, 2012

The sensitivity to surface profile of non-contact optical imaging, such as spatial frequency doma... more The sensitivity to surface profile of non-contact optical imaging, such as spatial frequency domain imaging, may lead to incorrect measurements of optical properties and consequently erroneous extrapolation of physiological parameters of interest. Previous correction methods have focused on calibration-based, model-based, and computationbased approached. We propose an experimental method to correct the effect of surface profile on spectral images. Three-dimensional (3D) phantoms were built with acrylonitrile butadiene styrene (ABS) plastic using an accurate 3D imaging and an emergent 3D printing technique. In this study, our method was utilized for the correction of optical properties (absorption coefficient μ a and reduced scattering coefficient μ s ′) of objects obtained with a spatial frequency domain imaging system. The correction method was verified on three objects with simple to complex shapes. Incorrect optical properties due to surface with minimum 4 mm variation in height and 80 degree in slope were detected and improved, particularly for the absorption coefficients. The 3D phantom-based correction method is applicable for a wide range of purposes. The advantages and drawbacks of the 3D phantombased correction methods are discussed in details.

IEEE International Conference on Communications, 2005. ICC 2005. 2005

One of the major weaknesses of existing peer-to-peer (P2P) networks is that their overlay structu... more One of the major weaknesses of existing peer-to-peer (P2P) networks is that their overlay structures do not correlate to the physical underlying network topology. As a result, the overlays waste network resources and introduce excessive end-toend latency for P2P applications. In this paper, we present a new model for topology-aware overlay formation. Firstly, it clusters nodes that are close to each other in terms of network latency and network membership. Secondly, it discovers the underlying topology between clusters to form an efficient overlay. The model is self-organising and distributed without the need of global knowledge

Organizational Research Methods, 2007

Measurement artifacts, including measurement errors and scale-specific factors, distort observed ... more Measurement artifacts, including measurement errors and scale-specific factors, distort observed correlations between measures of psychological and organizational constructs. The authors discuss two alternative procedures, one using the generalized coefficient of equivalence and stability (GCES) and one based on structural equation modeling, to correct for the biasing effect of measurement artifacts in order to estimate construct-level relationships. Assumptions underlying the procedures are discussed and the degrees of biases resulting from violating the assumptions are examined by means of Monte Carlo simulation. They then propose an approach using cumulative knowledge in the literature about properties of measures of a construct to estimate the GCES. That approach can allow researchers to estimate relationships between constructs in most research situations. The authors apply the approach to estimate the GCES for overall job satisfaction, an important organizational construct.

Breast cancer cells from patients hold an important role in antigen production for immunotherapy,... more Breast cancer cells from patients hold an important role in antigen production for immunotherapy, drug testing, and cancer stem cell studies. To date, although many studies have been conducted to develop protocols for the isolation and culture of breast cancer cells from tumour biopsies, the efficiencies of these protocols remain low. This study aimed to identify a suitable medium for the isolation and propagation of primary breast cancer cells from breast tumour biopsies. Breast tumour biopsies were obtained from hospitals after all patients had given their written informed consent and were cultured according to the expanding tumour method in 3 different media: DMEM/F12 (Dulbecco's Modified Eagle Medium: Nutrient Mixture F-12) supplemented with 10% FBS (Fetal bovine serum) and 1% antibiotic-antimycotic (Medium D); Medium 171 supplemented with 1X MEGS (Mammary Epithelial Growth Supplement) and 1% antibiotic-antimycotic (Medium M); or a 1:1 mixture of Medium D and Medium M (Mediu...

Journal of biomedical optics, 2018

This paper reports the development and system analysis of a laparoscopic system based on structur... more This paper reports the development and system analysis of a laparoscopic system based on structured illumination technique capable of three-dimensional (3-D) reconstruction of porcine intestine during surgical anastomosis (connection of tubular structures). A calibration target is used to validate the system performance and results show a depth of field of 20 mm with an accuracy of 0.008 mm and precision of 0.25 mm. The imaging system is used to reconstruct a quantitative 3-D depth measurement of ex vivo porcine bowel tissues to mimic an end-to-end bowel anastomosis scenario. We demonstrate that the system can detect a suture in the tissue and map homogeneous surfaces of the intestine with different tissue pigments, affirming the feasibility for depth quantization for guiding and assisting medical diagnostic decisions in anastomosis surgery.

Chinese Optics Letters, 2017

An endoscopic imaging system using a plenoptic technique to reconstruct 3-D information is demons... more An endoscopic imaging system using a plenoptic technique to reconstruct 3-D information is demonstrated and analyzed in this Letter. The proposed setup integrates a clinical surgical endoscope with a plenoptic camera to achieve a depth accuracy error of about 1 mm and a precision error of about 2 mm, within a 25 mm × 25 mm field of view, operating at 11 frames per second.

OncoTargets and Therapy, 2016

Background: Breast cancer (BC) is one of the leading cancers in women. Recent progress has enable... more Background: Breast cancer (BC) is one of the leading cancers in women. Recent progress has enabled BC to be cured with high efficiency. However, late detection or metastatic disease often renders the disease untreatable. Additionally, relapse is the main cause of death in BC patients. Breast cancer stem cells (BCSCs) are considered to cause the development of BC and are thought to be responsible for metastasis and relapse. This study aimed to target BCSCs using dendritic cells (DCs) to treat tumor-bearing humanized mice models. Materials and methods: NOD/SCID mice were used to produce the humanized mice by transplantation of human hematopoietic stem cells. Human BCSCs were injected into the mammary fat pad to produce BC humanized mice. Both hematopoietic stem cells and DCs were isolated from the human umbilical cord blood, and immature DCs were produced from cultured mononuclear cells. DCs were matured by BCSC-derived antigen incubation for 48 hours. Mature DCs were vaccinated to BC humanized mice with a dose of 10 6 cells/mice, and the survival percentage was monitored in both treated and untreated groups. Results: The results showed that DC vaccination could target BCSCs and reduce the tumor size and prolong survival. Conclusion: These results suggested that targeting BCSCs with DCs is a promising therapy for BC.

The views expressed herein are those of the authors and do not necessarily reflect the views of t... more The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peerreviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.

Journal of biomedical optics, 2015

Intestinal anastomosis is a surgical procedure that restores bowel continuity after surgical rese... more Intestinal anastomosis is a surgical procedure that restores bowel continuity after surgical resection to treat intestinal malignancy, inflammation, or obstruction. Despite the routine nature of intestinal anastomosis procedures, the rate of complications is high. Standard visual inspection cannot distinguish the tissue subsurface and small changes in spectral characteristics of the tissue, so existing tissue anastomosis techniques that rely on human vision to guide suturing could lead to problems such as bleeding and leakage from suturing sites. We present a proof-of-concept study using a portable multispectral imaging (MSI) platform for tissue characterization and preoperative surgical planning in intestinal anastomosis. The platform is composed of a fiber ring light-guided MSI system coupled with polarizers and image analysis software. The system is tested on ex vivo porcine intestine tissue, and we demonstrate the feasibility of identifying optimal regions for suture placement.

2000 IEEE International Integrated Reliability Workshop Final Report (Cat. No.00TH8515)

As VLSI technologies are scaled into the deep submicron region, traditional hot-carrier reliabili... more As VLSI technologies are scaled into the deep submicron region, traditional hot-carrier reliability criteria can no longer be satisfied. A more realistic reliability criteria based on circuit performance, that takes into account both the physics of the degradation as well as its impact on device and circuit performance, is necessary. The current method of assessing hot-carrier reliability through simulation is an ad hoc approach, requires extensive tool calibration and yields no insights to the problem at hand. This study proposes a unified approach to evaluating hot-carrier reliability of analog circuits. First, by choosing the appropriate device model that can link device behavior to circuit performance, hot-carrier degradation can be treated as perturbations to device parameters, and therefore, can be correctly reflected at the circuit level. Second, device-level performance parameters (such as I d , gm, and gds) are studied in detail as functions of process parameters VT and J-l. This allows easy prediction of device-level parameter degradation by monitoring just two process parameters. Third, by taking advantage of well-developed circuit-analysis techniques, the small-signal device parameters gm and gds are used as independent variables to Circuit Degradation Models (CDMs), where the degradation of circuitlevel DC parameters of analog sub circuits can be modeled reasonably well as 'perturbations' in VT and J-l. This provides insights into how circuits may behave as various devices within the circuit degrade due to hot-carrier degradation. Finally, by analyzing the analog design space and examining hot-carrier degradation factors that are important to analog circuits, reliability and performance curves are presented as a way for designers and reliability engineers to define a more realistic and circuit-based criteria for hot-carrier degradation.

Biomedical Research and Therapy, 2015

Breast cancer cells from patients hold an important role in antigen production for immunotherapy,... more Breast cancer cells from patients hold an important role in antigen production for immunotherapy, drug testing, and cancer stem cell studies. To date, although many studies have been conducted to develop protocols for the isolation and culture of breast cancer cells from tumour biopsies, the efficiencies of these protocols remain low. This study aimed to identify a suitable medium for the isolation and propagation of primary breast cancer cells from breast tumour biopsies. Breast tumour biopsies were obtained from hospitals after all patients had given their written informed consent and were cultured according to the expanding tumour method in 3 different media: DMEM/F12 (Dulbecco's Modified Eagle Medium: Nutrient Mixture F-12) supplemented with 10% FBS (Fetal bovine serum) and 1% antibiotic-antimycotic (Medium D); Medium 171 supplemented with 1X MEGS (Mammary Epithelial Growth Supplement) and 1% antibiotic-antimycotic (Medium M); or a 1:1 mixture of Medium D and Medium M (Medium DB). The cell culture efficiency was evaluated by several criteria, including the time of cell appearance, cell morphology, capability of proliferation, cell surface marker expression, ALDH (Aldehyde dehydrogenases) activity, karyotype, and tumour formation capacity in immune-deficient mice. Notably, primary cancer cells cultured in Medium DB showed a high expression of breast cancer stem cell surface markers (including CD44 + CD24and CD49f +), low expression of stromal cell surface markers (CD90), high ALDH activity, an abnormal karyotype, and high tumour formation capacity in immune-deficient mice. These findings suggested that Medium DB was suitable to support the survival and proliferation of primary breast cancer cells as well as to enrich breast cancer stem cells.

2013 UKSim 15th International Conference on Computer Modelling and Simulation, 2013

The growth of mobile computing is changing the way people communicate. Mobile devices, especially... more The growth of mobile computing is changing the way people communicate. Mobile devices, especially mobile phones, have become cheaper and more powerful, and are able to run more applications and provide networking services. Mobile phones use fixed cellular infrastructure like base stations and transmission towers to enable users to share multimedia content and access the Internet anytime, anywhere. However, using telecommunications infrastructure introduces costs. Therefore, one of the solutions is to create impromptu ad hoc networks share information amongst users. Such networks are infrastructureless and organizing themselves, much like mobile ad hoc networks (MANETs). This paper investigates how mobile phones with low power Bluetooth technology can be used to create ad hoc networks that allow them to share information. The mobile phones should be able to organize themselves at the application layer of the Bluetooth protocol stack for multi-hop communication. Routing becomes important in order to achieve efficiency in data communication. Several existing routing protocols were implemented and evaluated for this type of network to determine how efficiently they deliver data and deal with network disruptions like a device moving out of transmission range.

Biomedical Optics Express, 2014

We propose a quantification method called Mapped Average Principal component analysis Score (MAPS... more We propose a quantification method called Mapped Average Principal component analysis Score (MAPS) to enumerate the contamination coverage on common medical device surfaces. The method was adapted from conventional Principal Component Analysis (PCA) on non-overlapped regions of a full frame hyperspectral image to resolve the percentage of contamination from the substrate. The concept was proven by using a controlled contamination sample with artificial test soil and color simulating organic mixture, and was further validated using a bacterial system including biofilm on stainless steel surface. We also validate the results of MAPS with other statistical spectral analysis including Spectral Angle Mapper (SAM). The proposed method provides an alternative quantification method for hyperspectral imaging data, which can be easily implemented by basic PCA analysis.

IEEE Transactions on Very Large Scale Integration (VLSI) Systems, 2015

Integrating multiple power converters on-chip improves energy efficiency of manycore architecture... more Integrating multiple power converters on-chip improves energy efficiency of manycore architectures. Switchedcapacitor (SC) dc-dc converters are compatible with conventional CMOS processes, but traditional implementations suffer from limited conversion efficiency. We propose a dynamic voltage and frequency scaling scheme with SC converters that achieves high converter efficiency by allowing the output voltage to ripple and having the processor core frequency track the ripple. Minimum core energy is achieved by hopping between different converter modes and tuning body-bias voltages. A multicore processor model based on a 28-nm technology shows conversion efficiencies of 90% along with over 25% improvement in the overall chip energy efficiency. Index Terms-Dynamic voltage and frequency scaling (DVFS), multicore processors, switched capacitor (SC). I. INTRODUCTION T HE growing need for energy efficiency while utilizing increased transistor densities has led to the development of manycore architectures. To maximize the energy efficiency of a processor when using dynamic voltage and frequency scaling (DVFS) [1], it is highly desirable to independently control the supply and the clock frequency for each core [2], [3].

2013 Fifth International Conference on Computational Intelligence, Communication Systems and Networks, 2013

We investigate and enhance the protocols that can bring connectivity to isolated village networks... more We investigate and enhance the protocols that can bring connectivity to isolated village networks via multiple data mules. These multiple mules communicate in order to find shorter reliable routes and provide higher probability of message delivery. Using movement traces for multiple data mules for rural-like areas the existing protocols ad hoc on-demand distance vector protocol (AODV) and optimal relay path (ORP) were compared. The results show that a rural route can provide telecommunication between the village networks, furthermore that AODV was more applicable to the network than ORP especially as the number of mules increase. Two enhancement algorithms (data mule inter-communicator (DMI) and ultimate data mule inter-communicator (UDMIC)) were developed using the existing protocols. The first enhancement was DMI that is based on using clustering of data to improve the performance between rural networks. The second enhancement was UDMIC, an adaptive algorithm that examines the situation to select an algorithm to improve performance. This enhancement not only managed to use the best of each protocol but in some cases improved network performance.

2012 26th International Conference on Advanced Information Networking and Applications Workshops, 2012

In this paper, we describe the performance of the B.A.T.M.A.N daemon (Batmand) protocol on an ind... more In this paper, we describe the performance of the B.A.T.M.A.N daemon (Batmand) protocol on an indoor Mesh Potato (MP) testbed. The MPs are small devices used for voice communications over the wireless medium but also supports data. The batmand protocol is designed for ad hoc wireless networks. We measure delay, packet loss in order to understand the MPs network performance. The experiments used packets of varying sizes over multiple hops. We analyze the data to see if the network latency for up to four hops is within the recommended boundaries set by ITU-Recommendation G. 114. We also observe the how the network's performance is affected by the varying packet sizes. Finally the experiments also reveal the common issues found on the wireless medium and also indoor testbeds.

2011 Third International Conference on Intelligent Networking and Collaborative Systems, 2011

In this paper, we describe the performance of the B.A.T.M.A.N advanced (Batman-adv) protocol on a... more In this paper, we describe the performance of the B.A.T.M.A.N advanced (Batman-adv) protocol on an indoor Mesh Potato (MP) testbed. The MPs are small devices used for voice communications over the wireless medium but also supports data. The Batman-adv protocol is designed for ad hoc wireless networks. We measure delay and packet loss, jitter and throughput in order to understand the MPs network performance. The experiments used packets of varying sizes over multiple hops. We analyze the data to see if the network latency for up to four hops is within the recommended boundaries set by ITU-Recommendation G. 114. We also observe the how the network's performance is affected by the varying packet sizes. Finally the experiments also reveal the common issues found on the wireless medium and also indoor testbeds.

2013 Fifth International Conference on Computational Intelligence, Communication Systems and Networks, 2013

The advancement of mobile phones is creating cheaper and more powerful devices that are capable o... more The advancement of mobile phones is creating cheaper and more powerful devices that are capable of providing networking services using readily available technologies embedded on mobile phones. Networking services are usually provided using fixed cellular infrastructure owned by Cellular Network Providers. The use of the cellular infrastructure incurs the cost of data exchange. One way to eliminate costs is to create spontaneous ad hoc networks that allow mobile phone users to connect directly and share information using technologies such as Bluetooth. In order to efficiently share information, routing techniques are needed that efficiently use the resources in these networks. This paper presents the design of a mobile phone ad hoc network and a prototype system that uses established routing algorithms to determine which routing protocols are well suited for such a network.

2012 26th International Conference on Advanced Information Networking and Applications Workshops, 2012

Traditionally data cannot be delivered between isolated networks. However by using a data mule wh... more Traditionally data cannot be delivered between isolated networks. However by using a data mule which is a combination between an electronic device and a mobile entity we can connect isolated networks. However, the main problem is that a long delay is experience and most of the time a large amount of undeliverable. In this paper we propose an algorithm that increases message delivery by clustering data mules in order to find a more reliable path between the sender and the receiver. Instead of data remaining on the same mule when travelling from one network to another, our algorithm allows mules to transfer data to nearby mules arriving to the destination network sooner. Using movement traces for the data mules for rural-like areas we compared two algorithms for a different number of nodes in the network and different communication ranges for each node. The preliminary results show that our proposed algorithm increases the network performance.

2009 International Conference on Network-Based Information Systems, 2009

Page 1. An agent based layered framework to facilitate intelligent Wireless Sensor Networks Hanh ... more Page 1. An agent based layered framework to facilitate intelligent Wireless Sensor Networks Hanh Le Department of Computer Science University of Cape Town Cape Town, South Africa hanh@cs.uct.ac.za André Scholtz Department ...

Biomedical Optics Express, 2012

The sensitivity to surface profile of non-contact optical imaging, such as spatial frequency doma... more The sensitivity to surface profile of non-contact optical imaging, such as spatial frequency domain imaging, may lead to incorrect measurements of optical properties and consequently erroneous extrapolation of physiological parameters of interest. Previous correction methods have focused on calibration-based, model-based, and computationbased approached. We propose an experimental method to correct the effect of surface profile on spectral images. Three-dimensional (3D) phantoms were built with acrylonitrile butadiene styrene (ABS) plastic using an accurate 3D imaging and an emergent 3D printing technique. In this study, our method was utilized for the correction of optical properties (absorption coefficient μ a and reduced scattering coefficient μ s ′) of objects obtained with a spatial frequency domain imaging system. The correction method was verified on three objects with simple to complex shapes. Incorrect optical properties due to surface with minimum 4 mm variation in height and 80 degree in slope were detected and improved, particularly for the absorption coefficients. The 3D phantom-based correction method is applicable for a wide range of purposes. The advantages and drawbacks of the 3D phantombased correction methods are discussed in details.

IEEE International Conference on Communications, 2005. ICC 2005. 2005

One of the major weaknesses of existing peer-to-peer (P2P) networks is that their overlay structu... more One of the major weaknesses of existing peer-to-peer (P2P) networks is that their overlay structures do not correlate to the physical underlying network topology. As a result, the overlays waste network resources and introduce excessive end-toend latency for P2P applications. In this paper, we present a new model for topology-aware overlay formation. Firstly, it clusters nodes that are close to each other in terms of network latency and network membership. Secondly, it discovers the underlying topology between clusters to form an efficient overlay. The model is self-organising and distributed without the need of global knowledge