On the design of optimization strategies based on global response surface approximation models

Striking the correct balance between global exploration of search spaces and local exploitation of promising basins of attraction is one of the principal concerns in the design of global optimization algorithms. This is true in the case of techniques based on global response surface approximation models as well. After constructing such a model using some initial database of designs it is far from obvious how to select further points to examine so that the appropriate mix of exploration and exploitation is achieved. In this paper we propose a selection criterion based on the expected improvement measure, which allows relatively precise control of the scope of the search. We investigate its behavior through a set of artificial test functions and two structural optimization problems. We also look at another aspect of setting up search heuristics of this type: the choice of the size of the database that the initial approximation is built upon

Magnetisation transfer ratio histogram analysis of primary progressive and other multiple sclerosis subgroups

INTRODUCTION: Global magnetisation transfer ration (MTR) histogram analysis in the brain offers a method for evaluating pathological change both as a result of lesions and microscopic changes in normal appearing tissues. METHODS: 39 controls and 83 MS patients (46 primary progressive, 11 benign, 10 relapsing-remitting, 16 secondary progressive) were studied to explore the relationship of six conventional MTR histogram parameters with MS clinical subgroups and disability. Principal component (PC) analysis, which makes use of all the histogram data, was also used to examine the relationship between the MTR histogram and disability. RESULTS: When primary progressive patients were compared to controls, there were abnormalities of average MTR, and MTR at the 25th, 50th and 75th percentile. Disabled relapsing onset patients exhibited abnormalities in the same four parameters. Benign and nondisabled relapsing onset patients exhibited no significant abnormalities. Modest correlations were observed between disability and individual MTR parameters in relapse onset but not primary progressive patients--PC analysis revealed stronger and significant associations with disability in both subgroups. (r=0.40 for primary progressive and r=0.51 for relapsing onset). CONCLUSION: A number of MTR parameters are abnormal in primary progressive MS. MTR abnormalities are seen in disabled patients, whether of relapsing or primary progressive onset. The improved correlation with disability obtained by PC analysis suggests a useful role of this method for following clinically relevant pathological changes depicted in the MTR histogram

Early Childhood Exposures to Fluorides and Child Behavioral Development and Executive Function: A Population-Based Longitudinal Study

Published online: January 2023It is important to both protect the healthy development and maintain the oral health of the child population. The study examined the effect of early childhood exposures to water fluoridation on measures of school-age executive functioning and emotional and behavioral development in a population-based sample. This longitudinal follow-up study used information from Australia’s National Child Oral Health Study 2012–14. Children aged 5 to 10 y at baseline were contacted again after 7 to 8 y, before they had turned 18 y of age. Percent lifetime exposed to fluoridated water (%LEFW) from birth to the age 5 y was estimated from residential history and postcode-level fluoride levels in public tap water. Measures of children’s emotional and behavioral development were assessed by the Strength and Difficulties Questionnaire (SDQ), and executive functioning was measured by the Behavior Rating Inventory of Executive Function (BRIEF). Multivariable regression models were generated to compare the associations between the exposure and the primary outcomes and controlled for covariates. An equivalence test was also conducted to compare the primary outcomes of those who had 100% LEFW against those with 0% LEFW. Sensitivity analysis was also conducted. A total of 2,682 children completed the SDQ and BRIEF, with mean scores of 7.0 (95% confidence interval, 6.6–7.4) and 45.3 (44.7–45.8), respectively. Those with lower %LEFW tended to have poorer scores of the SDQ and BRIEF. Multivariable regression models reported no association between exposure to fluoridated water and the SDQ and BRIEF scores. Low household income, identifying as Indigenous, and having a neurodevelopmental diagnosis were associated with poorer SDQ/BRIEF scores. An equivalence test confirmed that the SDQ/BRIEF scores among those with 100% LEFW were equivalent to that of those who had 0% LEFW. Exposure to fluoridated water during the first 5 y of life was not associated with altered measures of child emotional and behavioral development and executive functioning.L.G Do, A.J Spencer, A. Sawyer, A. Jones, S. Leary, R. Roberts, D.H H

The normal appearing grey matter in primary progressive multiple sclerosis. A magnetisation transfer imaging study

Background In 10-15 % of patients with multiple sclerosis (MS), the clinical course is characterized by slow progression in disability without relapses (primary progressive (PP) MS). The mechanism of disability in this form of MS is poorly understood. Using magnetization transfer ratio (MTR) imaging, we investigated normal appearing white matter (NAWM) and normal appearing grey matter (NAGM) in PPMS and explored the relationship of MTR measures with disability. Methods Thirty patients with PPMS and 30 age matched controls had spin echo based MTR imaging to study lesions and normal appearing tissues. The brain was segmented into NAWM and NAGM using SPM99 with lesions segmented using a semiautomated local thresholding technique. A 75% probability threshold for classification of NAWM and NAGM was used to diminish partial volume effects. From normalized histograms of MTR intensity values, six MTR parameters were measured. Mean lesion MTR and T2 lesion volume were also measured. Disability was assessed using Kurtzke's expanded disability status scale (EDSS). Results Compared with controls, patients exhibited a significant reduction in mean NAWM (p = 0.001) and NAGM (p = 0.004) MTR. Spearman's rank correlation of EDSS with the six MTR parameters in NAWM and NAGM, mean lesion MTR, and T2 lesion volume, was only significant with mean NAGM MTR (r = -0.41, p = 0.02), the 25(th) percentile of NAGM MTR intensity (r = -0.37, p = 0.05), and T2 lesion volume (r = 0.39, p = 0.04). Multiple regression analysis of the relationship between EDSS and 4 MR parameters representing each tissue type (mean NAWM MTR, mean NAGM MTR, mean lesion MTR, T2 lesion volume) showed that the association of EDSS with mean NAGM MTR remained significant. Conclusions There appear to be significant abnormalities in the NAGM in PP MS. Further investigation of the pathological basis and functional significance of grey matter abnormality in PPMS is warranted

Group-based trajectories of maternal intake of sugar-sweetened beverage and offspring oral health from a prospective birth cohort study

Objectives: To investigate the trajectory of maternal intake of sugar-sweetened beverages (SSB) during the first five years of their child’s life and its effect on the child’s dental caries at five years-of-age. Methods: This is an ongoing prospective population-based birth cohort study in Adelaide, Australia. Mothers completed questionnaires on their SSB intake, socioeconomic factors and health behaviors at the birth of their child and at the ages of one, two and five years. Child dental caries measured as decayed, missing, or filled tooth surfaces was collected by oral examination. Maternal SSB intake was used to estimate the trajectory of SSB intake. The trajectories then became the main exposure of the study. Dental caries at age five years were the primary outcomes. Adjusted mean- and prevalence-ratios were estimated for dental caries, controlling for confounders. Results: 879 children had dental examinations at five years-of-age. Group-based trajectory modeling identified three trajectories of maternal SSB intake: ‘Stable low’ (40.8%), ‘Moderate but increasing’ (13.6%), and ‘High early’ trajectory (45.6%). Multivariable regression analysis found children of mothers in the ‘High early’ and ‘Moderate but increasing’ groups to have greater experience of dental caries (MR: 1.37 (95%CI 1.01-1.67), and 1.24 (95%CI 0.96-1.60) than those in the ‘Stable low’ trajectory, respectively. Conclusion: Maternal consumption of SSB during pregnancy and in the early postnatal period influenced their offspring’s oral health. It is important to create a low-sugar environment from early childhood. The results suggest that health promotion activities need to be delivered to expecting women or soon after childbirth

sj-docx-1-jdr-10.1177_00220345221119431 – Supplemental material for Early Childhood Exposures to Fluorides and Child Behavioral Development and Executive Function: A Population-Based Longitudinal Study

Supplemental material, sj-docx-1-jdr-10.1177_00220345221119431 for Early Childhood Exposures to Fluorides and Child Behavioral Development and Executive Function: A Population-Based Longitudinal Study by L.G. Do, A.J. Spencer, A. Sawyer, A. Jones, S. Leary, R. Roberts and D.H. Ha in Journal of Dental Research</p

A Trust-Region Algorithm for Global Optimization

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Trajectories of child free sugars intake and dental caries - a population-based birth cohort study

Objectives: To investigate the association between trajectories of free sugars intake during the first five years of life and dental caries experience at five years. Methods: Data from the SMILE population-based prospective birth cohort study, collected at one, two and five years old, were used. A 3-days dietary diary and food frequency questionnaire were used to estimate free sugars intake (FSI) in grams. The primary outcomes were dental caries prevalence and experience (dmfs). The Group Based Trajectory Modelling method was used to characterize three FSI trajectories (‘Low and increasing’; ‘Mod erate and increasing’; and ‘High and increasing’), which were the main exposures. Multivariable regression models were generated to compute adjusted prevalence ratios (APR) and rate ratios (ARR) for the exposure, controlling for socioeconomic factors. Results: The prevalence of caries was 23.3%, with a mean dmfs of 1.4, and a median of 3.0 among those who had caries. There were clear gradients of caries prevalence and experience by the FSI trajectories. The ‘High and increasing’ had an APR of 2.13 (95%CI 1.23-3.70) and ARR of 2.77 (95%CI 1.45-5.32) against the ‘Low and increasing’. The ‘Moderate and increasing’ group had intermediate estimates. A quarter of the caries cases could have been prevented if the whole study sample had been in the ‘Low and increasing’ FSI trajectory. Conclusion: A sustained, high trajectory of FSI from a young age was positively associated with child dental caries. Measures to minimise consumption of free sugars must commence early in life. Clinical significance: The study has provided high level evidence to inform clinicians’ decisions in promoting a healthy dietary pattern for young children