Lourens Walters

Lourens Walters

Bearpark, England, United Kingdom
3K followers 500+ connections

About

At Informa I execute advanced analytics and AI roadmaps, formulating strategies for…

Articles by Lourens

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Activity

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Experience

  • Informa Graphic

    Informa

    London Area, United Kingdom

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    Durham, England, United Kingdom

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    Sedgefield, England, United Kingdom

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    Cape Town Area, South Africa

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    Cape Town Area, South Africa

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    Cape Town Area, South Africa

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Education

  • University of Cape Town Graphic

    University of Cape Town

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    Dissertation Title: A Web Browsing Workload Model for Simulation.

    Field: Computer Network Traffic Modeling and Analysis.

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    Field: Computer Network Security

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Licenses & Certifications

Volunteer Experience

  • Amazon Web Services (AWS) Graphic

    AWS Community Builder (ML/ Data Science)

    Amazon Web Services (AWS)

    - Present 3 years 6 months

    Science and Technology

    AWS Community Builder in the ML team supporting the community with ML/ Data Science expertise.

Publications

  • Risk Factors for Incident Diabetes in a Cohort Taking First-Line Nonnucleoside Reverse Transcriptase Inhibitor-Based Antiretroviral Therapy

    Medicine

    Efavirenz is the preferred nonnucleoside reverse transcriptase inhibitor (NNRTI) in first-line antiretroviral therapy (ART) regimens in low- and middle-income countries, where the prevalence of diabetes is increasing. Randomized control trials have shown mild increases in plasma glucose in participants in the efavirenz arms, but no association has been reported with overt diabetes. We explored the association between efavirenz exposure and incident diabetes in a large Southern African cohort…

    Efavirenz is the preferred nonnucleoside reverse transcriptase inhibitor (NNRTI) in first-line antiretroviral therapy (ART) regimens in low- and middle-income countries, where the prevalence of diabetes is increasing. Randomized control trials have shown mild increases in plasma glucose in participants in the efavirenz arms, but no association has been reported with overt diabetes. We explored the association between efavirenz exposure and incident diabetes in a large Southern African cohort commencing NNRTI-based first-line ART. Our cohort included HIV-infected adults starting NNRTI-based ART in a private sector HIV disease management program from January 2002 to December 2011. Incident diabetes was identified by the initiation of diabetes treatment. Patients with prevalent diabetes were excluded. We included 56,298 patients with 113,297 patient-years of follow-up (PYFU) on first-line ART. The crude incidence of diabetes was 13.24 per 1000 PYFU. Treatment with efavirenz rather than nevirapine was associated with increased risk of developing diabetes (hazard ratio 1.27 (95% confidence interval (CI): 1.10-1.46)) in a multivariate analysis adjusting for age, sex, body mass index, baseline CD4 count, viral load, NRTI backbone, and exposure to other diabetogenic medicines. Zidovudine and stavudine exposure were also associated with an increased risk of developing diabetes. We found that treatment with efavirenz, as well as stavudine and zidovudine, increased the risk of incident diabetes. Interventions to detect and prevent diabetes should be implemented in ART programs, and use of antiretrovirals with lower risk of metabolic complications should be encouraged.

    Other authors
    • S. Karamchand
    • R. Leisegang
    • M. Schomaker
    • G. Maartens
    • M. Hislop
    • J.A. Dave
    • N.S. Levitt
    • K. Cohen
    See publication
  • Clinical Presentation and Outcome of Tuberculosis in HIV Infected Children on Anti-Retroviral Therapy.

    BMC Pediatrics

    Background

    The tuberculosis (TB) and human immunodeficiency virus (HIV) epidemics are poorly controlled in sub-Saharan Africa, where highly active antiretroviral treatment (HAART) has become more freely available. Little is known about the clinical presentation and outcome of TB in HIV-infected children on HAART.

    Methods

    We performed a comprehensive file review of all children who commenced HAART at Tygerberg Children's Hospital from January 2003 through December…

    Background

    The tuberculosis (TB) and human immunodeficiency virus (HIV) epidemics are poorly controlled in sub-Saharan Africa, where highly active antiretroviral treatment (HAART) has become more freely available. Little is known about the clinical presentation and outcome of TB in HIV-infected children on HAART.

    Methods

    We performed a comprehensive file review of all children who commenced HAART at Tygerberg Children's Hospital from January 2003 through December 2005.

    Results

    Data from 290 children were analyzed; 137 TB episodes were recorded in 136 children; 116 episodes occurred before and 21 after HAART initiation; 10 episodes were probably related to immune reconstitution inflammatory syndrome (IRIS). The number of TB cases per 100 patient years were 53.3 during the 9 months prior to HAART initiation, and 6.4 during post HAART follow-up [odds ratio (OR) 16.6; 95% confidence interval (CI) 12.5–22.4]. A positive outcome was achieved in 97/137 (71%) episodes, 6 (4%) cases experienced no improvement, 16 (12%) died and the outcome could not be established in 18 (13%). Mortality was less in children on HAART (1/21; 4.8%) compared to those not on HAART (15/116; 12.9%).

    Conclusion

    We recorded an extremely high incidence of TB among HIV-infected children, especially prior to HAART initiation. Starting HAART at an earlier stage is likely to reduce morbidity and mortality related to TB, particularly in TB-endemic areas. Management frequently deviated from standard guidelines, but outcomes in general were good.

    Other authors
    See publication
  • Analyzing Storage System Workloads.

    In Proceedings of the South African Telecommunications Networks and Applications Conference

    Disk storage subsystems have not kept up the speed with processors. Processor performance has
    been increasing at a much higher rate than that of disk drives. Therefore, I/O subsystem has become a bottleneck in current computer systems. With this in mind the research community is looking into ways of improving the I/O subsystem. IBM and HP are among the organizations doing research and development of high performance storage systems also referred to as Enterprise Storage Systems (ESSs). Much…

    Disk storage subsystems have not kept up the speed with processors. Processor performance has
    been increasing at a much higher rate than that of disk drives. Therefore, I/O subsystem has become a bottleneck in current computer systems. With this in mind the research community is looking into ways of improving the I/O subsystem. IBM and HP are among the organizations doing research and development of high performance storage systems also referred to as Enterprise Storage Systems (ESSs). Much of this effort goes into the evaluation of these systems for correctness and performance.

    For these evaluations, using simulations or otherwise, to be reliable, there is need to correctly understand and model the disk I/O workloads also known as I/O traffic or physical I/O workloads.
    Therefore in our work, we analyzed I/O workload traces to derive statistics which can be used as a guide in the (a) modelling of I/O workload and subsequent production of I/O workload representative of the actual I/O workload for evaluation and (b) optimization of the storage systems. Our results show that the distribution of interarrival times of I/O requests are heavy-tailed, and that the I/O request sizes are a function of the operating system.

    Other authors
    • Paul G. Sikalinda
    • Pieter S. Kritzinger
    See publication
  • A Web Browsing Workload Model for Simulation

    Masters Thesis Dissertation - University of Cape Town

    *First author

    See publication
  • A Web Browsing Traffic Model for Simulation: Measurement and Analysis

    Proceedings of the Sixth Annual South African Telecommunications Networks and Applications Conference

    *First author

    See publication
  • Cellular Networks: Past, Present and Future.

    ACM Crossroads Magazine

    Mobile communication is the fastest growing field in the telecommunications industry. The most successful mobile communication system is the cellular radio network. A cellular radio network is used to transmit voice and data. Data transmission over a cellular network is a new service, which makes data networks accessible from mobile terminals via cellular telephones. This article discusses cellular radio network technology and its applications, especially pertaining to data transmission. Its…

    Mobile communication is the fastest growing field in the telecommunications industry. The most successful mobile communication system is the cellular radio network. A cellular radio network is used to transmit voice and data. Data transmission over a cellular network is a new service, which makes data networks accessible from mobile terminals via cellular telephones. This article discusses cellular radio network technology and its applications, especially pertaining to data transmission. Its history, present state, operation and planned future developments are explained.

    See publication
  • Traffic Modeling for Mobile Communication Networks

    Proceedings of the Third Annual South African Telecommunications Networks and Applications Conference

    *First author

  • SAINT - Secure Active Integrated Networks

    Proceedings of the Second Annual South African Telecommunications Networks and Applications Conference

    *Joint first author

    Other authors

Courses

  • 2014: Leading in Complex Times - Connemara

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  • 2018: Architecting on AWS - Torque IT

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  • 2018: Effective Personal Productivity - Leadership Management International

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Projects

  • Can Machine Learning assist with Coronory Artery Disease diagnosis?

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    The business area of concern for this analysis is that of the diagnosis of Coronary Artery Disease by medical practitioners. Currently, the Gold Standard for diagnosis is Angiography. The problem we are investigating, is that in many settings too many Angiograms are being performed which could result in poorer patient care and outcomes.

    Coronary Artery Disease (CAD ) is a disease in which there is a narrowing or blockage of the coronary arteries (blood vessels that carry blood and oxygen…

    The business area of concern for this analysis is that of the diagnosis of Coronary Artery Disease by medical practitioners. Currently, the Gold Standard for diagnosis is Angiography. The problem we are investigating, is that in many settings too many Angiograms are being performed which could result in poorer patient care and outcomes.

    Coronary Artery Disease (CAD ) is a disease in which there is a narrowing or blockage of the coronary arteries (blood vessels that carry blood and oxygen to the heart). Coronary heart disease is usually caused by atherosclerosis (a buildup of fatty material and plaque inside the coronary arteries). We attempt to answer the following business questions by performing this analysis.
    Can data science be used to improve the diagnosis of Coronary Artery Disease by means of using existing data sources e.g. by using predictive modelling instead of Angiography?
    If predictive modelling cannot replace Angiography, can data science be used to reduce the number of Angiograms performed in settings where this is problematic?
    What are the 4 factors most highly correlated with CAD within our dataset?

  • Can Machine Learning make Lithium-ion Battery manufacturing more sustainable?

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    Lithium-ion batteries are utilised widely due to their low and falling costs, high energy densities and long lifetimes. However, developing batteries with a long lifetime entails experimentation of many months to years due to delayed feedback on performance for different chemical compositions. Expensive lab equipment is used to test battery degradation by means of running many batteries through repeated charge and discharge cycles.

    To improve research efficiency these experimental…

    Lithium-ion batteries are utilised widely due to their low and falling costs, high energy densities and long lifetimes. However, developing batteries with a long lifetime entails experimentation of many months to years due to delayed feedback on performance for different chemical compositions. Expensive lab equipment is used to test battery degradation by means of running many batteries through repeated charge and discharge cycles.

    To improve research efficiency these experimental workbenches are reproduced many times to increase testing speed. This is however both expensive, and due to long charge/ recharge cycles still does not reduce testing times where many different chemical compositions must be tested in sequence.

    Accurate prediction of battery lifetime using early-cycle data would unlock new opportunities in battery production, use and optimization. For example, manufacturers can accelerate the cell development cycle, perform rapid validation of new manufacturing processes and sort/ grade new cells by their expected lifetime. This will reduce battery development costs and time as well as improving battery quality by enabling the testing of a wider variety of chemical compositions within the same budget and time.

    A low-carbon economy is essential in combating climate change which ranks in the top five priorities of most developed countries’ economic goals.

    The discovery and development of novel materials in the field of renewable energy are essential to accelerate the transition to a low-carbon economy. Technological advancements for which discovery of functional materials is however a prerequisite. The introduction of AI/ ML in the research and development of novel chemical formulations has largely been accepted as a possible means to achieve this objective.

    Shorter research times and lower costs of renewable energy sources will result in larger uptake of renewable energy sources which will in effect lead to a faster ramp up to a net-zero economy.

Honors & Awards

  • Barbara Starfield Award

    Johns Hopkins University

    Lourens Walters, Stefan Strydom and Cristina Mannie of Medscheme South Africa received this award in recognition of their use of the ACG System in their project titled “A comprehensive care management programme focused on emerging and high risk individuals”. Their work was presented at the ACG International User Conference in Seattle in April 2014.

    The aim of Medscheme’s research was to identify individuals within lower morbidity groups who were most likely to incur increasing…

    Lourens Walters, Stefan Strydom and Cristina Mannie of Medscheme South Africa received this award in recognition of their use of the ACG System in their project titled “A comprehensive care management programme focused on emerging and high risk individuals”. Their work was presented at the ACG International User Conference in Seattle in April 2014.

    The aim of Medscheme’s research was to identify individuals within lower morbidity groups who were most likely to incur increasing healthcare costs in the future, but would still be amenable to care management intervention programs. What differentiated their approach from other methods of identifying patients for care management programs, was their recognition that when tracking costs over future time periods for individuals in the lower Resource Utilization Bands (RUBs), the average healthcare expenditure for these individuals increases dramatically even though their current costs are relatively lower than those associated with higher RUBs. A predictive model utilizing the ACG System was developed to predict the likelihood of moving to a higher RUB in the future. This new the Emerging Risk Model complements their existing care management approach of focusing on high risk individuals. By intervening on high risk individuals, identified by applying their existing High Risk Predictive Model which also utilizes the ACG System, their randomized controlled study observed financial savings and a reduction in utilization of hospital services. Individuals identified by the Emerging Risk Model are likely to benefit from similar interventions due to a similar disease profile. A randomized controlled study is planned to measure intervention outcomes. The ACG System is also utilized by Medscheme South Africa to measure clinical and financial outcomes by means of ongoing case matched cohort studies tracking the effect of the care management programme.

  • Accenture Innovation Index Finalist 2014

    Accenture

    The emerging health risk model

    Transforming healthcare for people with chronic illness from a system that is reactive - responding mainly when a person is sick - to one that is proactive and focused on keeping a person as healthy as possible.

    Description of innovation

    Identifying individuals within lower morbidity groups most likely to incur increasing healthcare costs in future, but amenable to disease management programs.

    A predictive model was developed to…

    The emerging health risk model

    Transforming healthcare for people with chronic illness from a system that is reactive - responding mainly when a person is sick - to one that is proactive and focused on keeping a person as healthy as possible.

    Description of innovation

    Identifying individuals within lower morbidity groups most likely to incur increasing healthcare costs in future, but amenable to disease management programs.

    A predictive model was developed to predict the likelihood of moving to a higher morbidity group. The model was found to be very accurate. This emerging risk sub-population is the perfect candidate for lifestyle/ wellness/ disease management interventions aimed at long term improvement of health status to avoid deterioration in health leading to high morbidity status. A pilot to intervene on this population was started during 2014. We are tracking the efficacy of the intervention in terms of health outcomes. This new approach complements existing disease management focusing on high risk individuals, which observed financial savings and a reduction in utilisation of hospital services during a randomized controlled trial and subsequent case matched studies. These programs empower healthcare professionals to focus care optimally by applying population health management principles.

Languages

  • English

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  • Afrikaans

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Organizations

  • Private Healthcare Information Standards Committee (PHISC)

    Chairperson of the Electronic Health Record Subcommittee

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    The PHISC EHR workgroup brings together various role players in the South African healthcare industry to discuss and develop a set of standards/ guidelines governing the content, transfer and interpretation of Electronic Health Records with the goal to improve inter-operability between systems in order to assist patients, healthcare service providers and other role players in the healthcare environment. The standards/ guidelines are developed by…

    The PHISC EHR workgroup brings together various role players in the South African healthcare industry to discuss and develop a set of standards/ guidelines governing the content, transfer and interpretation of Electronic Health Records with the goal to improve inter-operability between systems in order to assist patients, healthcare service providers and other role players in the healthcare environment. The standards/ guidelines are developed by PHISC members for its members. The standards/ guidelines are developed in accordance with the Health Normative Standards Framework (HNSF) which is an extension of the National Health Act.

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