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  1. Article ; Online: Offline reinforcement learning for safer blood glucose control in people with type 1 diabetes.

    Emerson, Harry / Guy, Matthew / McConville, Ryan

    Journal of biomedical informatics

    2023  Volume 142, Page(s) 104376

    Abstract: The widespread adoption of effective hybrid closed loop systems would represent an important milestone of care for people living with type 1 diabetes (T1D). These devices typically utilise simple control algorithms to select the optimal insulin dose for ... ...

    Abstract The widespread adoption of effective hybrid closed loop systems would represent an important milestone of care for people living with type 1 diabetes (T1D). These devices typically utilise simple control algorithms to select the optimal insulin dose for maintaining blood glucose levels within a healthy range. Online reinforcement learning (RL) has been utilised as a method for further enhancing glucose control in these devices. Previous approaches have been shown to reduce patient risk and improve time spent in the target range when compared to classical control algorithms, but are prone to instability in the learning process, often resulting in the selection of unsafe actions. This work presents an evaluation of offline RL for developing effective dosing policies without the need for potentially dangerous patient interaction during training. This paper examines the utility of BCQ, CQL and TD3-BC in managing the blood glucose of the 30 virtual patients available within the FDA-approved UVA/Padova glucose dynamics simulator. When trained on less than a tenth of the total training samples required by online RL to achieve stable performance, this work shows that offline RL can significantly increase time in the healthy blood glucose range from 61.6±0.3% to 65.3±0.5% when compared to the strongest state-of-art baseline (p<0.001). This is achieved without any associated increase in low blood glucose events. Offline RL is also shown to be able to correct for common and challenging control scenarios such as incorrect bolus dosing, irregular meal timings and compression errors. The code for this work is available at: https://github.com/hemerson1/offline-glucose.
    MeSH term(s) Humans ; Diabetes Mellitus, Type 1/drug therapy ; Hypoglycemic Agents/therapeutic use ; Blood Glucose ; Glycemic Control ; Blood Glucose Self-Monitoring ; Insulin ; Algorithms
    Chemical Substances Hypoglycemic Agents ; Blood Glucose ; Insulin
    Language English
    Publishing date 2023-05-04
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2057141-0
    ISSN 1532-0480 ; 1532-0464
    ISSN (online) 1532-0480
    ISSN 1532-0464
    DOI 10.1016/j.jbi.2023.104376
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Open-Path Atmospheric Transmission of Diode-Pumped Alkali Lasers in Maritime and Desert Environments.

    Rice, Christopher A / Pitz, Greg A / Guy, Matthew R / Perram, Glen P

    Applied spectroscopy

    2023  Volume 77, Issue 4, Page(s) 335–349

    Abstract: A tunable diode laser absorption spectroscopy (TDLAS) device has been developed to study long-path atmospheric transmission near diode pumped alkali laser (DPAL) emission wavelengths. By employing a single aperture and retro reflector in a mono-static ... ...

    Abstract A tunable diode laser absorption spectroscopy (TDLAS) device has been developed to study long-path atmospheric transmission near diode pumped alkali laser (DPAL) emission wavelengths. By employing a single aperture and retro reflector in a mono-static configuration, the noise associated with atmospheric and platform jitter were reduced by a factor of ∼30 and the open-air path length was extended to 4.4 km and over a very broad spectral range, up to 120 cm
    Language English
    Publishing date 2023-02-02
    Publishing country United States
    Document type Journal Article
    ISSN 1943-3530
    ISSN (online) 1943-3530
    DOI 10.1177/00037028221144642
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Trade and dietary preferences can determine micronutrient security in the United Kingdom.

    Poppy, Guy Matthew / Baverstock-Poppy, Joseph James / Baverstock, Jenny

    Nature food

    2022  Volume 3, Issue 7, Page(s) 512–522

    Abstract: Food production, dietary choices, climate change, trade tariffs and future responses to the SARS-CoV-2 pandemic are some of the factors affecting global food security. Here we examine how micronutrient security has varied in the United Kingdom from 1961 ... ...

    Abstract Food production, dietary choices, climate change, trade tariffs and future responses to the SARS-CoV-2 pandemic are some of the factors affecting global food security. Here we examine how micronutrient security has varied in the United Kingdom from 1961 to 2017, before Brexit, taking supply and demand driver changes into account. We also introduce future scenarios to see how a more plant-based diet and/or differing trade arrangement post-European Union exit and COVID-19 pandemic could affect the supply of nutrients. Results show that trading agreements have affected several key micronutrients during the past 60 years and are likely to be influential in a post-Brexit United Kingdom. Changes in dietary patterns, which influence how much animal- and plant-based products are consumed, have also affected micronutrient security and are likely to do so in the future with increased interest in consuming a more plant-based diet.
    Language English
    Publishing date 2022-07-14
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 2662-1355
    ISSN (online) 2662-1355
    DOI 10.1038/s43016-022-00538-3
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Perfusion Imaging and Inflammation Biomarkers Provide Complementary Information in Alzheimer's Disease.

    Michopoulou, Sofia / Prosser, Angus / Dickson, John / Guy, Matthew / Teeling, Jessica L / Kipps, Christopher

    Journal of Alzheimer's disease : JAD

    2023  Volume 96, Issue 3, Page(s) 1317–1327

    Abstract: Background: Single photon emission tomography (SPECT) can detect early changes in brain perfusion to support the diagnosis of dementia. Inflammation is a driver for dementia progression and measures of inflammation may further support dementia diagnosis. ...

    Abstract Background: Single photon emission tomography (SPECT) can detect early changes in brain perfusion to support the diagnosis of dementia. Inflammation is a driver for dementia progression and measures of inflammation may further support dementia diagnosis.
    Objective: In this study, we assessed whether combining imaging with markers of inflammation improves prediction of the likelihood of Alzheimer's disease (AD).
    Methods: We analyzed 91 participants datasets (Institutional Ethics Approval 20/NW/0222). AD biomarkers and markers of inflammation were measured in cerebrospinal fluid. Statistical parametric mapping was used to quantify brain perfusion differences in perfusion SPECT images. Logistic regression models were trained to evaluate the ability of imaging and inflammation markers, both individually and combined, to predict AD.
    Results: Regional perfusion reduction in the precuneus and medial temporal regions predicted Aβ42 status. Increase in inflammation markers predicted tau and neurodegeneration. Matrix metalloproteneinase-10, a marker of blood-brain barrier regulation, was associated with perfusion reduction in the right temporal lobe. Adenosine deaminase, an enzyme involved in sleep homeostasis and inflammation, was the strongest predictor of neurodegeneration with an odds ratio of 10.3. The area under the receiver operator characteristic curve for the logistic regression model was 0.76 for imaging and 0.76 for inflammation. Combining inflammation and imaging markers yielded an area under the curve of 0.85.
    Conclusions: Study results showed that markers of brain perfusion imaging and markers of inflammation provide complementary information in AD evaluation. Inflammation markers better predict tau status while perfusion imaging measures represent amyloid status. Combining imaging and inflammation improves AD prediction.
    MeSH term(s) Humans ; Alzheimer Disease/diagnosis ; tau Proteins/cerebrospinal fluid ; Amyloid beta-Peptides/cerebrospinal fluid ; Biomarkers/cerebrospinal fluid ; Inflammation/diagnostic imaging ; Perfusion Imaging
    Chemical Substances tau Proteins ; Amyloid beta-Peptides ; Biomarkers
    Language English
    Publishing date 2023-11-27
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1440127-7
    ISSN 1875-8908 ; 1387-2877
    ISSN (online) 1875-8908
    ISSN 1387-2877
    DOI 10.3233/JAD-230726
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Book ; Online: Offline Reinforcement Learning for Safer Blood Glucose Control in People with Type 1 Diabetes

    Emerson, Harry / Guy, Matthew / McConville, Ryan

    2022  

    Abstract: The widespread adoption of effective hybrid closed loop systems would represent an important milestone of care for people living with type 1 diabetes (T1D). These devices typically utilise simple control algorithms to select the optimal insulin dose for ... ...

    Abstract The widespread adoption of effective hybrid closed loop systems would represent an important milestone of care for people living with type 1 diabetes (T1D). These devices typically utilise simple control algorithms to select the optimal insulin dose for maintaining blood glucose levels within a healthy range. Online reinforcement learning (RL) has been utilised as a method for further enhancing glucose control in these devices. Previous approaches have been shown to reduce patient risk and improve time spent in the target range when compared to classical control algorithms, but are prone to instability in the learning process, often resulting in the selection of unsafe actions. This work presents an evaluation of offline RL for developing effective dosing policies without the need for potentially dangerous patient interaction during training. This paper examines the utility of BCQ, CQL and TD3-BC in managing the blood glucose of the 30 virtual patients available within the FDA-approved UVA/Padova glucose dynamics simulator. When trained on less than a tenth of the total training samples required by online RL to achieve stable performance, this work shows that offline RL can significantly increase time in the healthy blood glucose range from 61.6 +\- 0.3% to 65.3 +/- 0.5% when compared to the strongest state-of-art baseline (p < 0.001). This is achieved without any associated increase in low blood glucose events. Offline RL is also shown to be able to correct for common and challenging control scenarios such as incorrect bolus dosing, irregular meal timings and compression errors.

    Comment: The code for this work is available at https://github.com/hemerson1/offline-glucose
    Keywords Computer Science - Machine Learning ; Computer Science - Artificial Intelligence
    Subject code 670
    Publishing date 2022-04-07
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Biomarkers of Inflammation Increase with Tau and Neurodegeneration but not with Amyloid-β in a Heterogenous Clinical Cohort.

    Michopoulou, Sofia / Prosser, Angus / Kipps, Christopher / Dickson, John / Guy, Matthew / Teeling, Jessica

    Journal of Alzheimer's disease : JAD

    2022  Volume 89, Issue 4, Page(s) 1303–1314

    Abstract: Background: Neuroinflammation is an integral part of Alzheimer's disease (AD) pathology. Inflammatory mediators can exacerbate the production of amyloid-β (Aβ), the propagation of tau pathology and neuronal loss.: Objective: To evaluate the ... ...

    Abstract Background: Neuroinflammation is an integral part of Alzheimer's disease (AD) pathology. Inflammatory mediators can exacerbate the production of amyloid-β (Aβ), the propagation of tau pathology and neuronal loss.
    Objective: To evaluate the relationship between inflammation markers and established markers of AD in a mixed memory clinic cohort.
    Methods: 105 cerebrospinal fluid (CSF) samples from a clinical cohort under investigation for cognitive complaints were analyzed. Levels of Aβ42, total tau, and phosphorylated tau were measured as part of the clinical pathway. Analysis of inflammation markers in CSF samples was performed using multiplex immune assays. Participants were grouped according to their Aβ, tau, and neurodegeneration status and the Paris-Lille-Montpellier (PLM) scale was used to assess the likelihood of AD.
    Results: From 102 inflammatory markers analyzed, 19 and 23 markers were significantly associated with CSF total tau and phosphorylated tau levels respectively (p < 0.001), while none were associated with Aβ42. The CSF concentrations of 4 inflammation markers were markedly elevated with increasing PLM class indicating increased likelihood of AD (p < 0.001). Adenosine deaminase, an enzyme involved in sleep homeostasis, was the single best predictor of high likelihood of AD (AUROC 0.788). Functional pathway analysis demonstrated a widespread role for inflammation in neurodegeneration, with certain pathways explaining over 30% of the variability in tau values.
    Conclusion: CSF inflammation markers increase significantly with tau and neurodegeneration, but not with Aβ in this mixed memory clinic cohort. Thus, such markers could become useful for the clinical diagnosis of neurodegenerative disorders alongside the established Aβ and tau measures.
    MeSH term(s) Adenosine Deaminase ; Alzheimer Disease/pathology ; Amyloid beta-Peptides/cerebrospinal fluid ; Biomarkers/cerebrospinal fluid ; Cognitive Dysfunction/cerebrospinal fluid ; Humans ; Inflammation ; Inflammation Mediators ; Peptide Fragments/cerebrospinal fluid ; tau Proteins/cerebrospinal fluid
    Chemical Substances Amyloid beta-Peptides ; Biomarkers ; Inflammation Mediators ; Peptide Fragments ; tau Proteins ; Adenosine Deaminase (EC 3.5.4.4)
    Language English
    Publishing date 2022-09-29
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1440127-7
    ISSN 1875-8908 ; 1387-2877
    ISSN (online) 1875-8908
    ISSN 1387-2877
    DOI 10.3233/JAD-220523
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: (111)In WBC SPECT/CT detection of a radiographically occult solitary infected renal cyst in polycystic kidney disease.

    Guy, Matthew S / Kardan, Arash

    Clinical nuclear medicine

    2015  Volume 40, Issue 6, Page(s) 542–544

    Abstract: Renal cyst infection-pyocystis-is a potentially life-threatening complication of autosomal-dominant polycystic kidney disease. Differentiation of pyocystis from pyelonephritis is important for antibiotic management. A 56-year-old woman with autosomal- ... ...

    Abstract Renal cyst infection-pyocystis-is a potentially life-threatening complication of autosomal-dominant polycystic kidney disease. Differentiation of pyocystis from pyelonephritis is important for antibiotic management. A 56-year-old woman with autosomal-dominant polycystic kidney disease and recurrent urinary tract infections was admitted to the hospital with suspicion of pyelonephritis. CT and static planar In-labeled WBC examinations failed to show a specific focus of infection. Abdominal imaging with In-labeled WBC SPECT/CT revealed abnormal leukocyte accumulation within a solitary right renal cyst. Precise SPECT/CT localization of the infected renal cyst is illustrated along with comparative CT images.
    MeSH term(s) Cysts/diagnostic imaging ; Cysts/pathology ; Female ; Humans ; Indium Radioisotopes ; Middle Aged ; Multimodal Imaging ; Polycystic Kidney, Autosomal Dominant/complications ; Polycystic Kidney, Autosomal Dominant/diagnostic imaging ; Pyelonephritis/complications ; Pyelonephritis/diagnostic imaging ; Radiopharmaceuticals ; Tomography, Emission-Computed, Single-Photon ; Tomography, X-Ray Computed ; Urinary Tract Infections/complications ; Urinary Tract Infections/diagnostic imaging
    Chemical Substances Indium Radioisotopes ; Radiopharmaceuticals
    Language English
    Publishing date 2015-06
    Publishing country United States
    Document type Case Reports ; Journal Article
    ZDB-ID 197628-x
    ISSN 1536-0229 ; 0363-9762
    ISSN (online) 1536-0229
    ISSN 0363-9762
    DOI 10.1097/RLU.0000000000000771
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Explainable Machine Learning for Real-Time Hypoglycemia and Hyperglycemia Prediction and Personalized Control Recommendations.

    Duckworth, Christopher / Guy, Matthew J / Kumaran, Anitha / O'Kane, Aisling Ann / Ayobi, Amid / Chapman, Adriane / Marshall, Paul / Boniface, Michael

    Journal of diabetes science and technology

    2022  Volume 18, Issue 1, Page(s) 113–123

    Abstract: Background: The occurrences of acute complications arising from hypoglycemia and hyperglycemia peak as young adults with type 1 diabetes (T1D) take control of their own care. Continuous glucose monitoring (CGM) devices provide real-time glucose readings ...

    Abstract Background: The occurrences of acute complications arising from hypoglycemia and hyperglycemia peak as young adults with type 1 diabetes (T1D) take control of their own care. Continuous glucose monitoring (CGM) devices provide real-time glucose readings enabling users to manage their control proactively. Machine learning algorithms can use CGM data to make ahead-of-time risk predictions and provide insight into an individual's longer term control.
    Methods: We introduce explainable machine learning to make predictions of hypoglycemia (<70 mg/dL) and hyperglycemia (>270 mg/dL) up to 60 minutes ahead of time. We train our models using CGM data from 153 people living with T1D in the CITY (CGM Intervention in Teens and Young Adults With Type 1 Diabetes)survey totaling more than 28 000 days of usage, which we summarize into (short-term, medium-term, and long-term) glucose control features along with demographic information. We use machine learning explanations (SHAP [SHapley Additive exPlanations]) to identify which features have been most important in predicting risk per user.
    Results: Machine learning models (XGBoost) show excellent performance at predicting hypoglycemia (area under the receiver operating curve [AUROC]: 0.998, average precision: 0.953) and hyperglycemia (AUROC: 0.989, average precision: 0.931) in comparison with a baseline heuristic and logistic regression model.
    Conclusions: Maximizing model performance for glucose risk prediction and management is crucial to reduce the burden of alarm fatigue on CGM users. Machine learning enables more precise and timely predictions in comparison with baseline models. SHAP helps identify what about a CGM user's glucose control has led to predictions of risk which can be used to reduce their long-term risk of complications.
    MeSH term(s) Adolescent ; Young Adult ; Humans ; Diabetes Mellitus, Type 1/complications ; Diabetes Mellitus, Type 1/drug therapy ; Blood Glucose ; Blood Glucose Self-Monitoring ; Hypoglycemia/diagnosis ; Hyperglycemia/diagnosis ; Glucose ; Machine Learning
    Chemical Substances Blood Glucose ; Glucose (IY9XDZ35W2)
    Language English
    Publishing date 2022-06-13
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1932-2968
    ISSN (online) 1932-2968
    DOI 10.1177/19322968221103561
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article: Fourier block noise reduction: an adaptive filter for reducing Poisson noise in scintigraphic images.

    Guy, Matthew J

    Nuclear medicine communications

    2008  Volume 29, Issue 3, Page(s) 291–297

    Abstract: Objectives: Both qualitative and quantitative analysis in nuclear medicine can be undermined by Poisson noise in low-count clinical images. Whilst the conventional smoothing filters are typically used do reduce noise, they also degrade the image ... ...

    Abstract Objectives: Both qualitative and quantitative analysis in nuclear medicine can be undermined by Poisson noise in low-count clinical images. Whilst the conventional smoothing filters are typically used do reduce noise, they also degrade the image structure. Fourier block noise reduction (FBNR) is an adaptive filtering approach, which attempts to reduce image noise and maintain image resolution and structure.
    Methods: Although a degree of automated flexibility is possible using conventional stationary pre-filtering, e.g. using a total image count-dependent Metz filter, resolution and contrast is degraded across the image. Adaptive non-stationary filtering has been applied by others in an attempt to maintain structure whilst reducing noise: instead of analysing the whole image, only a subset is used to determine each pixel's correction. Whilst the new software algorithm FBNR shares some common components with other adaptive non-stationary filters, it expressly includes the Poisson noise model within a simple and robust algorithm that can be applied to a diverse range of clinical studies.
    Results and conclusions: No additional artefacts were seen post-application of FBNR during evaluation using simulated and clinical images. Mean normalised error values indicate FBNR processing is equivalent to obtaining an unprocessed image with at least 2.5 times the number of counts.
    MeSH term(s) Algorithms ; Fourier Analysis ; Humans ; Image Enhancement/methods ; Image Interpretation, Computer-Assisted/methods ; Phantoms, Imaging ; Poisson Distribution ; Reproducibility of Results ; Sensitivity and Specificity ; Signal Processing, Computer-Assisted ; Tomography, Emission-Computed, Single-Photon/instrumentation ; Tomography, Emission-Computed, Single-Photon/methods
    Language English
    Publishing date 2008-03
    Publishing country England
    Document type Journal Article
    ZDB-ID 758141-5
    ISSN 1473-5628 ; 0143-3636
    ISSN (online) 1473-5628
    ISSN 0143-3636
    DOI 10.1097/MNM.0b013e3282f38f69
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Discovery Molecular Imaging Digital Ready PET/CT performance evaluation according to the NEMA NU2-2012 standard.

    Michopoulou, Sofia / O'Shaughnessy, Emma / Thomson, Katharine / Guy, Matthew J

    Nuclear medicine communications

    2018  Volume 40, Issue 3, Page(s) 270–277

    Abstract: Objectives: The aim of this study was to evaluate and benchmark the performance characteristics of the General Electric (GE) Discovery Molecular Imaging (MI) Digital Ready (DR) PET/CT.: Materials and methods: Performance evaluation against the ... ...

    Abstract Objectives: The aim of this study was to evaluate and benchmark the performance characteristics of the General Electric (GE) Discovery Molecular Imaging (MI) Digital Ready (DR) PET/CT.
    Materials and methods: Performance evaluation against the National Electrical Manufacturers Association (NEMA) 2012 standard was performed on three GE Discovery MI DR PET/CT systems installed across different UK centres. The Discovery MI DR performance was compared with the Siemens Biograph mCT Flow, Phillips Ingenuity TF and GE Discovery 690 fully analogue PET/CT systems. In addition, as the Discovery MI DR is upgradable to the Digital MI with silicon photomultipliers, performance characteristics between analogue and digital were compared with assess potential benefits of a system upgrade.
    Results: The average NEMA results across three Discovery MI DR scanners were: sensitivity 7.3 cps/kBq, spatial resolution full-width-half-maximum radial 5.5 mm, tangential 4.5 mm and axial 6 mm at 10 cm from the centre of the field-of-view, peak noise equivalent count rate 142 kcps, scatter fraction 37.1%, contrast recovery coefficients from the International Electrotechnical Commission phantom ranged from 52 to 87% for 10-37-mm diameter spheres.
    Conclusion: All three Discovery MI DR systems tested in this study exceeded the manufacturer's NEMA specification, yet variability between scanners was noted. Discovery MI DR showed similar performance to Discovery 690 and Ingenuity TF, but lower sensitivity and spatial resolution than Biograph mCT Flow. The Discovery MI DR showed lower spatial resolution and contrast recovery than the 20-cm field-of-view Digital MI.
    MeSH term(s) Positron Emission Tomography Computed Tomography/standards ; Reference Standards ; Societies
    Language English
    Publishing date 2018-11-29
    Publishing country England
    Document type Evaluation Studies ; Journal Article
    ZDB-ID 758141-5
    ISSN 1473-5628 ; 0143-3636
    ISSN (online) 1473-5628
    ISSN 0143-3636
    DOI 10.1097/MNM.0000000000000962
    Database MEDical Literature Analysis and Retrieval System OnLINE

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