E. Jammeh

Plymouth University, School of Computing and Mathematics, Post-Doc

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Identification of Optimum Panel of Blood-based Biomarkers for Alzheimer’s Disease Diagnosis Using Machine Learning

2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2018

With the increasing number of people living with Alzheimer's disease (AD), there is a need for lo... more With the increasing number of people living with Alzheimer's disease (AD), there is a need for low-cost and easy to use methods to detect AD early to facilitate access to appropriate care pathways. Neuroimaging biomarkers (such as those based on PET and MRI) and biochemical biomarkers (such as those based on CSF) are recommended by international guidelines to facilitate diagnosis. However, neuroimaging is expensive and may not be widely available and CSF testing is invasive. Bloodbased biomarkers offer the potential for the development of a low-cost and more time efficient tool to detect AD to complement CSF and neuroimaging as blood is much easier to obtain. Although no single blood biomarker is yet able to detect AD, combinations of biomarkers (also called panels) have shown good results. However, a large number of biomarkers are often needed to achieve a satisfactory detection performance. In addition, it is difficult to reproduce reported results within and across different study cohorts because of data overfitting and lack of access to the datasets used in the studies. In this study, our focus is to identify an optimum panel (in terms of the least number of blood biomarkers to meet the specified diagnostic performance of 80% sensitivity and specificity) based on a widely accessible data set, and to demonstrate a testing methodology that reinforces reproducibility of results. Realizing a panel with reduced number of markers will have significant impact on the complexity and cost of diagnosis and potential development of cost-effective point of care devices.

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A Robust Blood-based Signature of Cerebrospinal Fluid Aβ42 Status

2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), 2020

Early detection of Alzheimer's disease (AD) is of vital importance in the development of disease-... more Early detection of Alzheimer's disease (AD) is of vital importance in the development of disease-modifying therapies. This necessitates the use of early pathological indicators of the disease such as amyloid abnormality to identify individuals at early disease stages where intervention is likely to be most effective. Recent evidence suggests that cerebrospinal fluid (CSF) amyloid β1-42 (Aβ42) level may indicate AD risk earlier compared to amyloid positron emission tomography (PET). However, the method of collecting CSF is invasive. Bloodbased biomarkers indicative of CSF Aβ42 status may remedy this limitation as blood collection is minimally invasive and inexpensive. In this study, we show that APOE4 genotype and blood markers comprising EOT3, APOC1, CGA, and Aβ42 robustly predict CSF Aβ42 with high classification performance (0.84 AUC, 0.82 sensitivity, 0.62 specificity, 0.81 PPV and 0.64 NPV) using machine learning approach. Due to the method employed in the biomarker search, the identified biomarker signature maintained high performance in more than a single machine learning algorithm, indicating potential to generalize well. A minimally invasive and cost-effective solution to detecting amyloid abnormality such as proposed in this study may be used as a first step in a multi-stage diagnostic workup to facilitate enrichment of clinical trials and population-based screening.

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Robust EEG Based Biomarkers to Detect Alzheimer’s Disease

Brain Sciences, 2021

Biomarkers to detect Alzheimer’s disease (AD) would enable patients to gain access to appropriate... more Biomarkers to detect Alzheimer’s disease (AD) would enable patients to gain access to appropriate services and may facilitate the development of new therapies. Given the large numbers of people affected by AD, there is a need for a low-cost, easy to use method to detect AD patients. Potentially, the electroencephalogram (EEG) can play a valuable role in this, but at present no single EEG biomarker is robust enough for use in practice. This study aims to provide a methodological framework for the development of robust EEG biomarkers to detect AD with a clinically acceptable performance by exploiting the combined strengths of key biomarkers. A large number of existing and novel EEG biomarkers associated with slowing of EEG, reduction in EEG complexity and decrease in EEG connectivity were investigated. Support vector machine and linear discriminate analysis methods were used to find the best combination of the EEG biomarkers to detect AD with significant performance. A total of 325,56...

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$Research paper thumbnail of Higuchi fractal dimension of the electroencephalogram as a biomarker for early detection of Alzheimer's disease$

Higuchi fractal dimension of the electroencephalogram as a biomarker for early detection of Alzheimer's disease

2017 39th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2017

It is widely accepted that early diagnosis of Alzheimer's disease (AD) makes it possible for pati... more It is widely accepted that early diagnosis of Alzheimer's disease (AD) makes it possible for patients to gain access to appropriate health care services and would facilitate the development of new therapies. AD starts many years before its clinical manifestations and a biomarker that provides a measure of changes in the brain in this period would be useful for early diagnosis of AD. Given the rapid increase in the number of older people suffering from AD, there is a need for an accurate, low-cost and easy to use biomarkers that could be used to detect AD in its early stages. Potentially, the electroencephalogram (EEG) can play a vital role in this but at present, no reliable EEG biomarker exists for early diagnosis of AD. The gradual slowing of brain activity caused by AD starts from the back of the brain and spreads out towards other parts. Consequently, determining the brain regions that are first affected by AD may be useful in its early diagnosis. Higuchi fractal dimension (HFD) has characteristics which make it suited to capturing region-specific neural changes due to AD. The aim of this study is to investigate the potential of HFD of the EEG as a biomarker which is associated with the brain region first affected by AD. Mean HFD value was calculated for all channels of EEG signals recorded from 52 subjects (20-AD and 32-normal). Then, p-values were calculated between the two groups (AD and normal) to detect EEG channels that have a significant association with AD. knearest neighbor (KNN) algorithm was used to compute the distance between AD patients and normal subjects in the classification. Our results show that AD patients have significantly lower HFD values in the parietal areas. HFD values for channels in these areas were used to discriminate between AD and normal subjects with a sensitivity and specificity values of 100% and 80%, respectively.

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Complexity Measures for Quantifying Changes in Electroencephalogram in Alzheimer’s Disease

Complexity, 2018

Alzheimer’s disease (AD) is a progressive disorder that affects cognitive brain functions and sta... more Alzheimer’s disease (AD) is a progressive disorder that affects cognitive brain functions and starts many years before its clinical manifestations. A biomarker that provides a quantitative measure of changes in the brain due to AD in the early stages would be useful for early diagnosis of AD, but this would involve dealing with large numbers of people because up to 50% of dementia sufferers do not receive formal diagnosis. Thus, there is a need for accurate, low-cost, and easy to use biomarkers that could be used to detect AD in its early stages. Potentially, electroencephalogram (EEG) based biomarkers can play a vital role in early diagnosis of AD as they can fulfill these needs. This is a cross-sectional study that aims to demonstrate the usefulness of EEG complexity measures in early AD diagnosis. We have focused on the three complexity methods which have shown the greatest promise in the detection of AD, Tsallis entropy (TsEn), Higuchi Fractal Dimension (HFD), and Lempel-Ziv com...

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Identification of blood biomarkers for use in point of care diagnosis tool for Alzheimer's disease

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2016

Early diagnosis of Alzheimer's Disease (AD) is widely regarded as necessary to allow treatmen... more Early diagnosis of Alzheimer's Disease (AD) is widely regarded as necessary to allow treatment to be started before irreversible damage to the brain occur and for patients to benefit from new therapies as they become available. Low-cost point-of-care (PoC) diagnostic tools that can be used to routinely diagnose AD in its early stage would facilitate this, but such tools require reliable and accurate biomarkers. However, traditional biomarkers for AD use invasive cerebrospinal fluid (CSF) analysis and/or expensive neuroimaging techniques together with neuropsychological assessments. Blood-based PoC diagnostics tools may provide a more cost and time efficient way to assess AD to complement CSF and neuroimaging techniques. However, evidence to date suggests that only a panel of biomarkers would provide the diagnostic accuracy needed in clinical practice and that the number of biomarkers in such panels can be large. In addition, the biomarkers in a panel vary from study to study. Th...

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Case Study 1—Building Up a VoIP System Based on Asterisk

Computer Communications and Networks, 2013

In this case study, we will setup and configure VoIP testbed by using Asterisk PBX and X-Lite 4 s... more In this case study, we will setup and configure VoIP testbed by using Asterisk PBX and X-Lite 4 soft phone. Upon completion of this lab, you will be able to add SIP phones, configure basic dial-plans, setup SIP soft phone, start and stop Asterisk, make voice calls between SIP soft phones, make video calls between SIP soft phones and make voice calls between SIP soft phones and analogue phones.

Case Study 3—Mobile VoIP Applications and IMS

Computer Communications and Networks, 2013

This Lab introduces an Open Source IMS Core which deploys the main IMS call session control funct... more This Lab introduces an Open Source IMS Core which deploys the main IMS call session control functions described in Chap. 7 and IMSDroid as an IMS client. We will also outline the main steps needed for successful installation, configuration and setup of an Open Source IMS Core in Ubuntu and IMSDroid in an Android based mobile handset. We will finally demonstrate how to make SIP audio and video calls between two Android based mobile handsets via the Open Source IMS Core over Wi-Fi access network.

Case Study 2—VoIP Quality Analysis and Assessment

Computer Communications and Networks, 2013

In this case study, we will analyse and assess voice and video quality of the multimedia sessions... more In this case study, we will analyse and assess voice and video quality of the multimedia sessions established in Chap. 8. We will use Wireshark in order to capture and analyse SIP and RTP packet headers. Upon completion of this lab, you will be able to familiarize with Wireshark, tc commands in Linux network emulator, and experience SIP message flows during user registration and multimedia sessions setup and termination. This Lab will also help you to emulate Wide Area Network (WAN) by using tc command in Linux in order to assess the impact of packet loss and jitter on the quality of VoIP calls.

VoIP Signalling—SIP

Speech Compression

Guide to voice and video over IP: for fixed and mobile networks

This book presents a review of the latest advances in speech and video compression, computer netw... more This book presents a review of the latest advances in speech and video compression, computer networking protocols, the assessment and monitoring of VoIP quality, and next generation network architectures for multimedia services. The book also concludes with three case studies, each presenting easy-to-follow step-by-step instructions together with challenging hands-on exercises. Features: provides illustrative worked examples and end-of-chapter problems; examines speech and video compression techniques, together with speech and video compression standards; describes the media transport protocols RTP and RTCP, as well as the VoIP signalling protocols SIP and SDP; discusses the concepts of VoIP quality of service and quality of experience; reviews next-generation networks based on the IP multimedia subsystem and mobile VoIP; presents case studies on building a VoIP system based on Asterisk, setting up a mobile VoIP system based on Open IMS and Android mobile, and analysing VoIP protocols and quality.

Content-aware adaptation scheme for QoE optimized dash applications

2014 IEEE Global Communications Conference, 2014

The paper presents novel content-aware adaptation schemes for QoE optimized HTTP-based adaptive v... more The paper presents novel content-aware adaptation schemes for QoE optimized HTTP-based adaptive video streaming services. In recent years, content type has been investigated and proofed to have a deep influence on user's acceptable quality of experience (QoE). However, most of the existing HTTP-based adaptive video strategies only conduct bitrate switching according to network resources without a consideration of video content types. This may cause a non-optimal network resource allocation which may not achieve the optimized QoE for delivered video streaming services. In this paper, we proposed two content-aware adaptation schemes, named as Content-aware Probe and Adapt (C-PANDA) and Content-aware Dynamic Programming (C-DP), which are able to decide the video bitrate for the next video segment, based on not only the available bandwidth, the existing buffer capacity, but also the video content type. We implemented both content-aware adaptation algorithms in player prototypes based on libdash 3.0 library. Preliminary results show that content-aware adaptation schemes achieve better QoE when compared with conventional PANDA scheme. The proposed schemes are able to optimize QoE according to contents. They can achieve higher than acceptable QoE for most attractive contents such as those with high motion intensity to improve user experience for the most interesting scenes; select same video representations for segments belonging to a scene to avoid quality oscillation; and reserve buffer resource during low motion scenes to avoid stalling for the following high motion scenes. The work will be helpful in designing QoE-aware DASH schemes in the future.

VoIP Quality of Experience (QoE)

Computer Communications and Networks, 2013

Quality of Experience (QoE) is a term used to describe user perceived experience for a provided s... more Quality of Experience (QoE) is a term used to describe user perceived experience for a provided service, e.g. VoIP. This term is also referred to as User Perceived Quality of Service (PQoS) in order to differentiate with Network Quality of Service (QoS) which reflects network performance. Network QoS metrics generally include packet loss, delay and jitter which are the main impairments affecting voice and video quality in VoIP applications. The key QoE metric is Mean Opinion Score (MOS), an overall voice/video quality metric. In this chapter, the definition of QoS and QoS metrics will be introduced first. Then the characteristics of these metrics and how to obtain them in a practical way will be discussed. Further, the QoE concept and an overview of QoE measurement for VoIP applications will be presented. Finally, the most commonly used subjective and objective QoE measurement for voice and video will be presented in detail, including Perceptual Evaluation of Speech Quality (PESQ) and E-model for voice quality assessment, and Full-Reference (FR), Reduced-Reference (RR) and No-Reference (NR) models for video quality assessment.

Media Transport for VoIP

Computer Communications and Networks, 2013

TCP and UDP are the most commonly used transport layer protocols. TCP is a connection-oriented, r... more TCP and UDP are the most commonly used transport layer protocols. TCP is a connection-oriented, reliable, in-order transport protocol. Its features such as retransmission, flow control and congestion control are not suitable for real-time multimedia applications such as VoIP. UDP is a connectionless and unreliable transport protocol. Its simple header, non-retransmission and non-congestion-control features make it suitable for real-time applications. However, as UDP does not have the sequence number in the UDP header, the media stream packet transferred over UDP may experience duplication or arrive not in the right order. This will cause the received media (e.g., voice or video) unrecognisable or unviewable. The Real-time Transport Protocol (RTP) was developed to assist the transfer of real-time media streams on top of the unreliable UDP protocol. It has many fields, such as the sequence number (to detect packet loss), the timestamp (to know the location of media packet) and the payload type (to know voice or video codec used). The associated RTP Control Protocol (RTCP) was also developed to assist media control and QoS/QoE management for VoIP applications. This chapter presents the key concepts of RTP and RTCP, together with detailed header analysis based on real trace data using Wireshark. The compressed RTP (cRTP) and bandwidth efficiency issues are also discussed together with illustrative worked examples for VoIP bandwidth calculation.

IMS and Mobile VoIP

Computer Communications and Networks, 2013

The Internet evolution started from a small network linking a few research centres to a massive n... more The Internet evolution started from a small network linking a few research centres to a massive network with billions of computers. The reason behind the growth of the Internet has been its ability to provide very useful services such as World Wide Web, email, instant messaging, VoIP and video conferencing. On the other hand, cellular networks have experienced dramatic growth over the years. The cellular network growth was not only due to its services such as voice and video calls and short messaging services, but also because cellular network users can access the network from virtually everywhere. These facts prompted 3GPP to come up with the idea of the IP Multimedia Subsystem. The IP Multimedia Subsystem aims at merging cellular networks and the Internet, two of the most successful infrastructures in telecommunication. By merging the two infrastructures, the IP Multimedia Subsystem will be able to provide ubiquitous cellular access to all services that are provided by the Internet.

Feedback-Free Early VoIP Quality Adaptation Scheme in Next Generation Networks

2010 IEEE Global Telecommunications Conference GLOBECOM 2010, 2010

AbstractThe Next Generation Networks (NGNs) were pro-posed to provide ubiquitous access to multi... more

Open IMS Core with VoIP Quality Adaptation

2009 Fifth International Conference on Autonomic and Autonomous Systems, 2009

As IMS becomes more available to academia and industry, the requirements for IMS clients are grow... more As IMS becomes more available to academia and industry, the requirements for IMS clients are growing faster than ever. From all IMS components, IMS clients are vital components for the success of overall services provided by the IMS. Most of ongoing research is focusing on adding more services on clients side, none has been done for voice over Internet protocol (VoIP) quality adaptation so far. Since the end user is the only one to perceive the quality of services provided by the IMS network, this paper reports a testbed that demonstrates the concept of adaptation of VoIP system based on an open IMS core and open source mobile terminal.

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Quality of experience (QoE) driven adaptation scheme for voice/video over IP

Telecommunication Systems, 2010

Network quality of service (NQoS) of IP networks is unpredictable and impacts the quality of netw... more Network quality of service (NQoS) of IP networks is unpredictable and impacts the quality of networked multimedia services. Adaptive voice and video schemes are therefore vital for the provision of voice over IP (VoIP) services for optimised quality of experience (QoE). Traditional adaptation schemes based on NQoS do not take perceived quality into consideration even though the user is the best judge of quality. Additionally, uncertainties inherent in NQoS parameter measurements make the design of adaptation schemes difficult and their performance suboptimal. This paper presents a QoE-driven adaptation scheme for voice and video over IP to solve the optimisation problem to provide optimal QoE for networked voice and video applications. The adaptive VoIP architecture was implemented and tested both in NS2 and in an Open IMS Core network to allow extensive simulation and test-bed evaluation. Results show that the scheme was optimally responsive to available network bandwidth and congestion for both voice and video and optimised delivered QoE for different network conditions, and is friendly to TCP traffic.

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Quality of experience-driven adaptation scheme for video applications over wireless networks

IET Communications, 2010

User's perceived quality of service (QoS) or quality of experience (QoE) is likely to be the majo... more User's perceived quality of service (QoS) or quality of experience (QoE) is likely to be the major determining factor in the success of new multimedia applications over wireless/mobile networks. The primary aim of this study is to present an adaptation scheme that is QoE-driven for optimising content provisioning and network resource utilisation for video applications over wireless networks. The proposed scheme encompasses the application of a QoE-driven model for optimising content provisioning and network resource utilisation. The content provisioning is optimised by the determination of initial content quality by adapting the video sender bitrate (SBR) according to users' QoE requirement. By finding the impact of the QoS parameters on end-to-end perceptual video quality, the optimum trade-off between SBR and frame rate is found and the benefits to network providers in maximising existing network resources are demonstrated. The QoE is measured in terms of the mean opinion score. The proposed scheme makes it possible for content providers to achieve optimum streaming (with an appropriate SBR) suitable for the network and content type for a requested QoE. The scheme is also beneficial for network providers for network resource provision and planning, and therefore maximising existing network infrastructure by providing service differentiation.

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