Ajit Narayanan

Prof. Ajit Narayanan

orcid

Research Focus & Metrics

Academic Career Length

20Years (2007-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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2 June 2022 in Remote Sensing
Verified
Journal Article
Open access
PDF file
CBChristopher Burns
Christopher Burns
BBBarbara Anne Bollard
Barbara Anne Bollard
ANAjit Narayanan
Ajit Narayanan
Mapping and monitoring coral reef benthic composition using remotely sensed imagery provides a large-scale inference of spatial and temporal dynamics. These maps have become essential components in marine science and management, with their utility being dependent upon accuracy, scale, and repeatability. One of the primary factors that affects the utility of a coral reef benthic composition map is the choice of the machine-learning algorithm used to classify the coral reef benthic classes. Current machine-learning algorithms used to map coral reef benthic composition and detect changes over time achieve moderate to high overall accuracies yet have not demonstrated spatio-temporal generalisation. The inability to generalise limits their scalability to only those reefs where in situ reference data samples are present. This limitation is becoming more pronounced given the rapid increase in the availability of high temporal (daily) and high spatial resolution (<5 m) multispectral satellite imagery. Therefore, there is presently a need to identify algorithms capable of spatio-temporal generalisation in order to increase the scalability of coral reef benthic composition mapping and change detection. This review focuses on the most commonly used machine-learning algorithms applied to map coral reef benthic composition and detect benthic changes over time using multispectral satellite imagery. The review then introduces convolutional neural networks that have recently demonstrated an ability to spatially and temporally generalise in relation to coral reef benthic mapping; and recurrent neural networks that have demonstrated spatio-temporal generalisation in the field of land cover change detection. A clear conclusion of this review is that existing convolutional neural network and recurrent neural network frameworks hold the most potential in relation to increasing the spatio-temporal scalability of coral reef benthic composition mapping and change detection due to their ability to spatially and temporally generalise.

11 January 2022 in Journal of Pain and Symptom Management
Verified
Journal Article
Open access
MSMargaret H Sandham
Margaret H Sandham
EHEmma A. Hedgecock
Emma A. Hedgecock
RSRichard J. Siegert
Richard J. Siegert
ANAjit Narayanan
Ajit Narayanan
MHMevhibe B. Hocaoglu
Mevhibe B. Hocaoglu
IHIrene J. Higginson
Irene J. Higginson
The growth of patient reported outcome measures data in palliative care provides an opportunity for machine learning to identify patterns in patient responses signifying different phases of illness. The study will explore if machine learning and network analysis can identify phases in patient palliative status through symptoms reported on the Integrated Palliative Care Outcome Scale (IPOS). A partly cross-sectional and partially longitudinal observational study was undertaken using the Australasian Karnofsky Performance Scale (AKPS); Integrated Palliative Care Outcome Scale (IPOS); Phase of Illness (POI). Patient palliative records (n = 1507, 65% stable, 20% unstable, 9% deteriorating, 2% terminal) from 804 adult patients enrolled in a New Zealand palliative care service were analysed using a combination of statistical, machine learning and network analysis techniques. Data from IPOS showed considerable variation with phase. Also, network analysis showed clear associations between items by phase. Six machine learning techniques identified the most important variables for predicting possible transition between phases of illness. Network analysis for all patients showed that Poor Appetite and Loss of Energy were central IPOS items, with Loss of Energy linked to Drowsiness, Shortness of Breath and Lack of Mobility on the one hand, and Poor Appetite linked to Nausea, Vomiting, Constipation and Sore and Dry Mouth on the other. These preliminary results, when coupled with the latest technological developments in mobile apps and wearable technology, could point the way to increased use of digital therapeutics in continuous palliative care monitoring.

27 August 2009 in BMC Cancer
Verified
Journal Article
Open access
PDF file
SGSharon Glaysher
Sharon Glaysher
DYDennis Yiannakis
Dennis Yiannakis
FGFrancis G Gabriel
Francis G Gabriel
PJPenny Johnson
Penny Johnson
MPMarta Ewa Polak
Marta Ewa Polak
ICIan A Cree
Ian A Cree
NSCLC exhibits considerable heterogeneity in its sensitivity to chemotherapy and similar heterogeneity is noted in vitro in a variety of model systems. This study has tested the hypothesis that the molecular basis of the observed in vitro chemosensitivity of NSCLC lies within the known resistance mechanisms inherent to these patients' tumors.

19 May 2022 in Journal of Affective Disorders
Verified
Journal Article
Closed access
LGLisa Gossage
Lisa Gossage
ANAjit Narayanan
Ajit Narayanan
Joanna DipnallJoanna Dipnall
Joanna Dipnall
LILeon Iusitini
Leon Iusitini
ASAlexander Sumich
Alexander Sumich
RSRichard Siegert
Richard Siegert

1 August 2011 in Journal of Management & Marketing in Healthcare
Verified
Journal Article
Closed access
ANAjit Narayanan
Ajit Narayanan
MGM. Greco
M. Greco
HPH. Powell
H. Powell
TBT. Bealing
T. Bealing
The requirement for doctors and other medical professionals to undertake periodic performance evaluation is growing. Tools and techniques for such performance evaluation are at an early stage of development, but it is likely that feedback from colleagues and patients will play an important role. The aim of this paper is to evaluate two feedback tools (CFET for colleague feedback and DISQ for patient feedback) for the purpose of periodic performance evaluation of doctors. The data used in this study came from over 200 doctors currently working in hospital settings within the UK. The results indicate that there is close correspondence between the outcomes of manual screening procedures used by the UK General Medical Council (GMC) and the output from the two feedback tools Also, the paper shows that it is possible to combine colleague and patient feedback for a doctor, thereby extending our knowledge of how screening techniques based on questionnaires can produce a multisource view currently not available to manual screeners. The paper concludes that feedback tools such as CFET and DISQ, provided they are grounded in core aspects of good practice, can function as a first level of screening if and when periodic performance evaluation of large cohorts of doctors is carried out.No Full Tex

13 January 2025 in Journal of Medical Internet Research
Verified
Journal Article
Open access
USUpeka De Silva
Upeka De Silva
Samaneh MadanianSamaneh Madanian
Samaneh Madanian
Sharon OlsenSharon Olsen
Sharon Olsen
John TempletonJohn Templeton
John Templeton
CPChristian Poellabauer
Christian Poellabauer
RRRahmina Rubaiat
Rahmina Rubaiat
Background: Digital biomarkers are increasingly used in clinical decision support for various health conditions. Speech features as digital biomarkers can offer insights into underlying physiological processes due to the complexity of speech production. This process involves respiration, phonation, articulation, and resonance, all of which rely on specific motor systems for the preparation and execution of speech. Deficits in any of these systems can cause changes in speech signal patterns. Increasing efforts are being made to develop speech-based clinical decision support systems. Objective: This systematic scoping review investigated the technological revolution and recent digital clinical speech signal analysis trends to understand the key concepts and research processes from clinical and technical perspectives. Methods: A systematic scoping review was undertaken in 6 databases guided by a set of research questions. Articles that focused on speech signal analysis for clinical decision-making were identified, and the included studies were analyzed quantitatively. A narrower scope of studies investigating neurological diseases were analyzed using qualitative content analysis. Results: A total of 389 articles met the initial eligibility criteria, of which 72 (18.5%) that focused on neurological diseases were included in the qualitative analysis. In the included studies, Parkinson disease, Alzheimer disease, and cognitive disorders were the most frequently investigated conditions. The literature explored the potential of speech feature analysis in diagnosis, differentiating between, assessing the severity and monitoring the treatment of neurological conditions. The common speech tasks used were sustained phonations, diadochokinetic tasks, reading tasks, activity-based tasks, picture descriptions, and prompted speech tasks. From these tasks, conventional speech features (such as fundamental frequency, jitter, and shimmer), advanced digital signal processing–based speech features (such as wavelet transformation–based features), and spectrograms in the form of audio images were analyzed. Traditional machine learning and deep learning approaches were used to build predictive models, whereas statistical analysis assessed variable relationships and reliability of speech features. Model evaluations primarily focused on analytical validations. A significant research gap was identified: the need for a structured research process to guide studies toward potential technological intervention in clinical settings. To address this, a research framework was proposed that adapts a design science research methodology to guide research studies systematically. Conclusions: The findings highlight how data science techniques can enhance speech signal analysis to support clinical decision-making. By combining knowledge from clinical practice, speech science, and data science within a structured research framework, future research may achieve greater clinical relevance.