Multivariate Least Squares Regression Research Articles

Evaluation of four interventions using behavioural economics insights to increase demand for voluntary medical male circumcision in South Africa through the MoyaApp: A quasi-experimental study.

While voluntary medical male circumcision (VMMC) reduces the risk of HIV transmission by 60%, circumcision coverage falls short of the UNAIDS 90% VMMC target. We investigated whether behaviourally informed message framing increased demand for VMMC. Adult users of the MoyaApp, a data free application in South Africa, who viewed a form designed to generate interest in VMMC during August-November 2022. A quasi-experimental study was conducted to evaluate four MoyaApp VMMC intervention forms against the Standard of Care (SOC) form. All forms enabled users to provide contact details for follow-up engagement by a call centre. The primary outcome was the proportion of forms submitted. Secondary outcomes included successful contact with the user, VMMC bookings/referrals and confirmed circumcision. Multivariable ordinary least-squares regression was used for the analysis. Of 118,337 MoyaApp VMMC form viewers, 6% submitted a form. Foot-in-the-Door form viewers were more likely (+1.3 percentage points, p<0.01) to submit a form compared to the SOC group (6.3%). Active Choice (-1.1 percentage points, p<0.01) and Reserved for You (-0.05 percentage points, p<0.05) form viewers were less likely to submit a form compared to SOC. Users submitting on Foot-in-the-Door were less likely to be booked/referred compared to SOC (-5 percentage points, p<0.05). There were no differences between the intervention and SOC forms for successful contact and circumcisions. Message framing using behavioural insights was able to nudge men to engage with VMMC services. However, more work is needed to understand how to convert initial interest into bookings and circumcisions.

High-Precision and Rapid In Situ Ore Element Detection Based on Laser-Induced Breakdown Spectroscopy

In most cases, in situ online composition detection is highly desirable for the iron and steel industry. High-precision prediction of the iron content of an iron ore is quite difficult due to the complexity of ore composition. Herein, an online composition analysis system based on laser-induced breakdown spectroscopy (LIBS) is built up for real-time Fe concentration determination. Subsequently, using the support vector machine (SVM) combined with multivariate partial least-squares regression (PLSR) to establish a linear relationship between the spectral data and typical element content, the iron content in the standard ore tablet is used as the true value to train the model, and the iron content in the raw ore block is predicted, with an error of 1.6%. By studying the elemental distribution content of the raw ore with repeated laser ablation, it is found that the internal element content of the ore changes at different depths from the surface, and the element content quickly stabilizes. The results demonstrate that the method can accurately and effectively predict iron content online, allowing the application of online detection of industrial ore composition.

Land Use Impacts on Traffic Congestion Patterns: A Tale of a Northwestern Chinese City

Traffic congestion is a contemporary urban issue plaguing transportation planners, land developers, policy-makers, and citizens. While many studies have investigated the impact of built environments on traffic behavior in large metropolises on a regional scale, little attention has been paid to smaller urban areas, in China’s context, especially on a neighborhood level. This study investigates the spatial–temporal pattern of traffic congestion in a small-scale city, Xining, in China. By applying multivariate least-square regression analysis to social-sensing hyperlocal travel data, the results indicate that Xining is experiencing morning and evening traffic peaks on the weekdays and pre-weekends and only the evening peak during the weekends or holidays. The pre-weekend congestion is significantly worse than on a normal weekday, implying that stronger measures to consolidate traffic management should be implemented during this time. Educational land use and residential areas were found to contribute significantly to traffic congestion in Xining, and their combined effects tend to exacerbate the situation. The study furthers the understanding of traffic congestion in small urban areas, providing urban planners and policy-makers with new insights to formulate evidence-based strategies for mitigating traffic congestion.

Telehealth uptake among middle-aged and older Americans during COVID-19: chronic conditions, social media communication, and race/ethnicity

Objectives This study investigated whether and to what extent constructs of the protection motivation theory of health (PMT)—threat appraisal (perceived vulnerability/severity) and coping appraisal (response efficacy and self-efficacy)—are related to telehealth engagement during the COVID-19 pandemic, and how these associations differ by race/ethnicity among middle-aged and older Americans. Methods Data were from the 2020 Health and Retirement Study. Multivariable ordinary least-squares regression analyses were computed adjusting for health and sociodemographic factors. Results Some PMT constructs are useful in understanding telehealth uptake. Perceived vulnerability/severity, particularly comorbidity (b = 0.13, 95% confidence interval (CI) [0.11, 0.15], p < 0.001), and response efficacy, particularly participation in communication via social media (b = 0.24, 95% CI [0.21, 0.27], p < 0.001), were significantly and positively associated with higher telehealth uptake during the COVID-19 pandemic among middle-aged and older Americans. Non-Hispanic Black adults were more likely to engage in telehealth during the pandemic than their non-Hispanic White counterparts (b = 0.20, 95% CI [0.12, 0.28], p < 0.001). Multiple moderation analyses revealed the significant association between comorbidity and telehealth uptake was similar across racial/ethnic groups, whereas the significant association between social media communication and telehealth uptake varied by race/ethnicity. Specifically, the association was significantly less pronounced for Hispanic adults (b = −0.11, 95% CI [−0.19, −0.04], p < 0.01) and non-Hispanic Asian/other races adults (b = −0.13, 95% CI [−0.26, −0.01], p < 0.05) than it was for their non-Hispanic White counterparts. Conclusion Results suggest the potential of using social media and telehealth to narrow health disparities, particularly serving as a bridge for members of underserved communities to telehealth uptake.

Effects of general and central adiposity on circulating lipoprotein, lipid, and metabolite levels in UK Biobank: A multivariable Mendelian randomization study.

SummaryBackgroundThe direct effects of general adiposity (body mass index (BMI)) and central adiposity (waist-to-hip-ratio (WHR)) on circulating lipoproteins, lipids, and metabolites are unknown.MethodsWe used new metabolic data from UK Biobank (N=109,532, a five-fold higher N over previous studies). EDTA-plasma was used to quantify 249 traits with nuclear-magnetic-resonance spectroscopy including subclass-specific lipoprotein concentrations and lipid content, plus pre-glycemic and inflammatory metabolites. We used univariable and multivariable two-stage least-squares regression models with genetic risk scores for BMI and WHR as instruments to estimate total (unadjusted) and direct (mutually-adjusted) effects of BMI and WHR on metabolic traits; plus effects on statin use and interaction by sex, statin use, and age (proxy for medication use).FindingsHigher BMI decreased apolipoprotein B and low-density lipoprotein cholesterol (LDL-C) before and after WHR-adjustment, whilst BMI increased triglycerides only before WHR-adjustment. These effects of WHR were larger and BMI-independent. Direct effects differed markedly by sex, e.g., triglycerides increased only with BMI among men, and only with WHR among women. Adiposity measures increased statin use and showed metabolic effects which differed by statin use and age. Among the youngest (38-53y, statins-5%), BMI and WHR (per-SD) increased LDL-C (total effects: 0.04-SD, 95%CI=-0.01,0.08 and 0.10-SD, 95%CI=0.02,0.17 respectively), but only WHR directly. Among the oldest (63-73y, statins-29%), BMI and WHR directly lowered LDL-C (-0.19-SD, 95%CI=-0.27,-0.11 and -0.05-SD, 95%CI=-0.16,0.06 respectively).InterpretationExcess adiposity likely raises atherogenic lipid and metabolite levels exclusively via adiposity stored centrally, particularly among women. Apparent effects of adiposity on lowering LDL-C are likely explained by an effect of adiposity on statin use.FundingUK Medical Research Council; British Heart Foundation; Novo Nordisk; National Institute for Health Research; Wellcome Trust; Cancer Research UK

Nonveterinarian staff increase revenue and improve veterinarian productivity in mixed and companion animal veterinary practices in the United States.

To determine the contributions of veterinarians and support staff to revenue and veterinarian productivity (ie, number of patients seen/full-time-equivalent veterinarian/wk) in private mixed and companion animal practices in the US and identify staff-to-veterinarian labor ratios (SVLRs) that maximized these 2 practice outputs. 409 owners of mixed and companion animal practices who participated in the 2020 AVMA Practice Owner Survey. Data regarding owner demographics, practice characteristics, labor (defined as mean total hours worked/wk), and gross revenue in 2019 were obtained from participating practices. Multivariable ordinary least-squares regression was used to identify factors associated with revenue and productivity as well as the SVLRs at which revenue and productivity were maximized. For each 10% increase in total veterinarian hours worked per week, revenue increased by a mean of approximately 9%. A 1-unit increase in total number of technician hours used to support 1 hour of veterinarian work was associated with a 20.5% increase in revenue but with no change in productivity. The same increase in total number of nonmedical staff hours was associated with a 17.0% increase in revenue and 14.4% increase in productivity. In terms of revenue, the optimal SVLRs for veterinary technicians and nonmedical staff were 9:1 and 8:1, respectively. In terms of productivity, the optimal SVLR for nonmedical staff was 10:1. Findings confirmed the important role of nonveterinarian staff in revenue and veterinarian productivity in mixed animal and companion animal practices and may be useful for making evidence-based staffing decisions.

A study on prospective associations between adiposity and 7-year changes in movement behaviors among older women based on compositional data analysis

IntroductionIt is unclear whether adiposity leads to changes in movement behaviors, and there is a lack of compositional analyses of longitudinal data which focus on these associations. Using a compositional approach, this study aimed to examine the associations between baseline adiposity and 7-year changes in physical activity (PA) and sedentary behavior (SB) among elderly women. We also explored the longitudinal associations between change in adiposity and change in movement-behavior composition.MethodsThis longitudinal study included 176 older women (mean baseline age 62.8 (4.1) years) from Central Europe. Movement behavior was assessed by accelerometers and adiposity was measured by bioelectrical impedance analysis at baseline and follow-up. A set of multivariate least-squares regression analyses was used to examine the associations of baseline adiposity and longitudinal changes in adiposity as explanatory variables with longitudinal changes in a 3-part movement-behavior composition consisting of SB, light PA (LPA) and moderate-to-vigorous PA (MVPA) as outcome variables.ResultsNo significant associations were found between baseline adiposity and longitudinal changes in the movement-behavior composition (p > 0.05). We found significant associations of changes in body mass index (BMI) and fat mass percentage (FM%) with changes in the movement-behavior composition. An increase in BMI was associated with an increase of SB at the expense of LPA and MVPA (β = 0.042, p = 0.009) and with a decrease of MVPA in favor of SB and LPA (β = − 0.059, p = 0.037). An increase in FM% was significantly associated only with an increase of SB at the expense of LPA and MVPA (β = 0.019, p = 0.031).ConclusionsThis study did not support the assumption that baseline adiposity is associated with longitudinal changes in movement behaviors among elderly women, but we found evidence for change-to-change associations, suggesting that a 7-year increase in adiposity is associated with a concurrent increase of SB at the expense of LPA and MVPA and with a concurrent decrease of MVPA in favor of LPA and SB. Public health interventions are needed to simultaneously prevent weight gain and promote physically active lifestyle among elderly women.

Factors Affecting Undernutrition among School Children in Cebu, Philippines

ABSTRACT School children in vulnerable areas continue to be at risk for undernutrition. This study investigated the factors associated with the nutritional status of school children in a rural municipality in Cebu, Philippines. Children aged 6–12 years (n = 327) and their parents were asked to participate. Children’s anthropometric measurements were taken in schools, while interviews and measurements of parents were conducted at home. Children’s nutritional status was assessed using height-for-age (HAZ) and weight-for-age (WAZ) z scores, while body mass index (BMI) was used for parents. Children’s dietary patterns and physical activity, and household characteristics, such as food insecurity, eating practices, water/sanitation/hand washing facilities, and sociodemographic status, were collected. Of 327 school children, 37.3% were stunted, while 35.1% were underweight in this rural community. HAZ and WAZ were negatively associated with household size, and positively associated with household income and parental BMI in multivariate least-squares regression models. Severe food insecurity was negatively associated with WAZ, which suggested that the experiences of severe food insecurity (i.e., not eating for a day) had a significant impact on nutritional status of children.

Time Off Work After Childbirth and Breastfeeding Supportive Workplaces: Associations with Near-Exclusive Breastfeeding Trajectory Membership.

We aimed to determine whether the association between time off work and a near-exclusive breastfeeding trajectory is moderated by perceived employer support for breastfeeding. We conducted a secondary analysis of working mothers (n=1,468) from the Infant Feeding Practices Study II, a longitudinal observational (2005-2007) study of U.S. infant feeding behaviors. Previous studies have found four latent infant feeding subgroups in the Infant Feeding Practices Study II sample, each following a distinct breastfeeding intensity trajectory. Multivariate least-squares regression was conducted to estimate whether time off work after delivery predicted increased membership in the subgroup characterized by near-exclusive breastfeeding, and whether this association was moderated by perceived employer support for workplace breastfeeding. Both time off work and perception of more breastfeeding support were independently, positively related to probability of membership in the near-exclusive breastfeeding trajectory (β=0.16, p=.019, and β=0.14, p=.004, respectively). The interaction of these two factors suggests an attenuation effect. The addition of paid leave to the model did not change the estimates. The positive relationship between time off and trajectory membership was significant only for mothers who perceived their workplaces to be unsupportive of breastfeeding.

Identifying sociodemographic, programmatic and dietary drivers of anaemia reduction in pregnant Indian women over 10 years.

Anaemia is a major contributor to the global disease burden and half of pregnant women in India were anaemic in 2016. The aetiology of anaemia is complex, yet anaemia determinants are frequently examined in isolation. We sought to explore how shifts in sociodemographic (wealth, age at pregnancy, education, open defecation, cooking fuel type, household size), programmatic (iron-folic acid tablet consumption, antenatal care visits) and dietary factors (intake of Fe, folic acid, vitamin B12, phytate) predicted changes in anaemia prevalence. Nutrient levels for eighty-eight food items were multiplied by household consumption of these foods to estimate household-level nutrient supply. A synthetic panel data set was created from two rounds of the District Level Household and Facility Survey (2002-04 and 2012-13) and Household Consumer Expenditures Survey (2004-05 and 2011-12). Ordinary least-squares multivariate regression models were used. Districts (n 446) spanning north, north-east, central and south India. Pregnant women aged 15-49 years (n 17 138). In the model accounting for both non-dietary and dietary factors, increased age at pregnancy (P<0·001), reduced village-level open defecation (P=0·001), consuming more Fe (P<0·001) and folic acid (P=0·018) and less phytate (P=0·002), and urbanization (P=0·015) were associated with anaemia reductions. A 10 mg increase in daily household Fe supply from 2012 levels was associated with a 10 % reduction in anaemia. Public health interventions to combat anaemia in pregnant women should use a holistic approach, including promotion of delayed marriage, construction and use of toilets, and measures that facilitate adoption of nutrient-rich diets.

Association of gastrointestinal events with quality of life and treatment satisfaction in osteoporosis patients: results from the Medication Use Patterns, Treatment Satisfaction, and Inadequate Control of Osteoporosis Study (MUSIC OS)

SummaryThe purpose of this study was to assess the association of GI events with HRQoL and treatment satisfaction. The effect of baseline GI events persisted through 1 year of follow-up, as indicated by lower EQ-5D, OPAQ-SV, and treatment satisfaction scores among patients with vs without baseline GI events. The presence of GI events is an independent predictor of decreased HRQoL and treatment satisfaction in patients being treated for osteoporosis.IntroductionThe goal of this study was to assess the association of gastrointestinal (GI) events with health-related quality of life (HRQoL) and treatment satisfaction in patients being treated for osteoporosis.MethodsMUSIC OS was a multinational, prospective, observational study examining the impact of GI events on osteoporosis management in postmenopausal women. In this analysis, HRQoL and treatment satisfaction were assessed at baseline, 6, and 12 months and compared between patients with and without GI events. Covariate-adjusted scores were calculated using multivariate least-squares regression analysis, and differences between the mean scores of patients with and without baseline and post-baseline GI events were determined.ResultsAmong the 2959 patients in the analysis, unadjusted scores at each time point were lower (i.e., worse) for patients with GI events than patients without GI events. In adjusted analyses, the effect of baseline GI events persisted through 1 year of follow-up, as indicated by lower EQ-5D and OPAQ-SV scores at 12 months among patients with vs without baseline GI events (−0.04 for the EQ-5D utility score, −5.07 for the EQ-5D visual analog scale, −3.35 for OPAQ physical function, −4.60 for OPAQ emotional status, and −8.50 for OPAQ back pain; P ≤ 0.001 for all values). Decrements in month 12 treatment satisfaction scores were −6.46 for patients with baseline GI events and −7.88 for patients with post-baseline GI events.ConclusionsThe presence of GI events is an independent predictor of decreased HRQoL and treatment satisfaction in patients being treated for osteoporosis.

Plasma soluble CD163 is associated with postmortem brain pathology in human immunodeficiency virus infection.

Higher plasma soluble cluster of differentiation (CD)163 (sCD163), shed by monocytes and macrophages, correlates with neurocognitive impairment in HIV infection. We hypothesized that higher antemortem plasma or cerebrospinal fluid (CSF) sCD163 would be associated with greater postmortem neurodegeneration and/or microgliosis. Retrospective, postmortem observational study. We measured sCD163 levels in antemortem plasma (n = 54) and CSF (n = 32) samples from 74 HIV-seropositive participants (median 5 months before death) who donated their brains to research at autopsy. Postmortem, we quantified markers of synaptodendritic damage (microtubule-associated protein 2, synaptophysin), microgliosis [human leukocyte antigen DR (HLA-DR), ionized calcium-binding adaptor molecule 1], astrocytosis (glial fibrillary acidic protein), and impaired protein clearance (β-amyloid) in frontal cortex, hippocampus, putamen, and internal capsule. Multivariable least-squares regression was used to evaluate the association between plasma or CSF sCD163 and histological measures, correcting for multiple comparisons. Higher plasma sCD163 was associated with lower microtubule-associated protein 2 in frontal cortex [B = -0.23, 95% confidence interval (CI) -0.41 to -0.06, P = 0.04], putamen (B = 0.32, 95% CI -0.52 to -0.12, P = 0.02), and hippocampus (B = -0.23, 95% CI -0.35 to -0.10, P = 0.01), and with lower synaptophysin in hippocampus (B = -0.25, 95% CI -0.42 to -0.03, P = 0.02) but not putamen or frontal cortex (P > 0.05). Higher plasma sCD163 was associated with higher HLA-DR in putamen (B = 0.17, 95% CI 0.08 to 0.26, P = 0.008). CSF sCD163 was not associated with any histological measure (P > 0.05). Higher plasma sCD163 in life is associated with greater synaptodendritic damage and microglial activation in cortical and subcortical brain regions.

Comparative study on ATR-FTIR calibration models for monitoring solution concentration in cooling crystallization

In this paper calibration model building based on using an ATR-FTIR spectroscopy is investigated for in-situ measurement of the solution concentration during a cooling crystallization process. The cooling crystallization of L-glutamic Acid (LGA) as a case is studied here. It was found that using the metastable zone (MSZ) data for model calibration can guarantee the prediction accuracy for monitoring the operating window of cooling crystallization, compared to the usage of undersaturated zone (USZ) spectra for model building as traditionally practiced. Calibration experiments were made for LGA solution under different concentrations. Four candidate calibration models were established using different zone data for comparison, by using a multivariate partial least-squares (PLS) regression algorithm for the collected spectra together with the corresponding temperature values. Experiments under different process conditions including the changes of solution concentration and operating temperature were conducted. The results indicate that using the MSZ spectra for model calibration can give more accurate prediction of the solution concentration during the crystallization process, while maintaining accuracy in changing the operating temperature. The primary reason of prediction error was clarified as spectral nonlinearity for in-situ measurement between USZ and MSZ. In addition, an LGA cooling crystallization experiment was performed to verify the sensitivity of these calibration models for monitoring the crystal growth process.

Dynamic 2-Deoxy-2-[18F]Fluoro-D-Glucose Positron Emission Tomography for Chemotherapy Response Monitoring of Breast Cancer Xenografts.

Non-invasive response monitoring can potentially be used to guide therapy selection for breast cancer patients. We employed dynamic 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography ([18F]FDG PET) to evaluate changes in three breast cancer xenograft lines in mice following three chemotherapy regimens. Sixty-six athymic nude mice bearing bilateral breast cancer xenografts (two basal-like and one luminal-like subtype) underwent three 60min [18F]FDG PET scans. Scans were performed prior to and 3 and 10days after treatment with doxorubicin, paclitaxel, or carboplatin. Tumor growth was monitored in parallel. A pharmacokinetic compartmental model was fitted to the tumor uptake curves, providing estimates of transfer rates between the vascular, non-metabolized, and metabolized compartments. Early and late standardized uptake values (SUVE and SUVL, respectively); the rate constants k 1, k 2, and k 3, and the intravascular fraction v B were estimated. Changes in tumor volume were used as a response measure. Multivariate partial least-squares regression (PLSR) was used to assess if PET parameters could model tumor response and to identify PET parameters with the largest impact on response. Treatment responders had significantly larger perfusion-related parameters (k 1 and k 2) and lower metabolism-related parameter (k 3) than non-responders 10days after the start of treatment. These findings were further supported by the PLSR analysis, which showed that k 1 and k 2 at day 10 and changes in k 3 explained most of the variability in response to therapy, whereas SUVL and particularly SUVE were of lesser importance. Overall, rate parameters related to both tumor perfusion and metabolism were associated with tumor response. Conventional metrics of [18F]FDG uptake such as SUVE and SUVL apparently had little relation to tumor response, thus necessitating full dynamic scanning and pharmacokinetic analysis for optimal evaluation of chemotherapy-induced changes in breast cancers.

Polycyclic aromatic hydrocarbons: determinants of residential carpet dust levels and risk of non-Hodgkin lymphoma.

To investigate the risk of non-Hodgkin lymphoma (NHL) associated with residential carpet dust measurements of polycyclic aromatic hydrocarbons (PAHs). We evaluated the relationship between residential carpet dust PAH concentrations (benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene, dibenz(a,h)anthracene, and indeno(1,2,3-c,d)pyrene, and their sum) and risk of NHL (676 cases, 511 controls) in the National Cancer Institute Surveillance Epidemiology and End Results multicenter case-control study. As a secondary aim, we investigated determinants of dust PAH concentrations. We computed odds ratios (OR) and 95 % confidence interval (CI) for associations between NHL and concentrations of individual and summed PAHs using unconditional logistic regression, adjusting for age, gender, and study center. Determinants of natural log-transformed PAHs were investigated using multivariate least-squares regression. We observed some elevated risks for NHL overall and B cell lymphoma subtypes in association with quartiles or tertiles of PAH concentrations, but without a monotonic trend, and there was no association comparing the highest quartile or tertile to the lowest. In contrast, risk of T cell lymphoma was significantly increased among participants with the highest tertile of summed PAHs (OR = 3.04; 95 % CI, 1.09-8.47) and benzo(k)fluoranthene (OR = 3.20; 95 % CI, 1.13-9.11) compared with the lowest tertile. Predictors of PAH dust concentrations in homes included ambient air PAH concentrations and the proportion of developed land within 2 km of a residence. Older age, more years of education, and white race were also predictive of higher levels in homes. Our results suggest a potential link between PAH exposure and risk of T cell lymphoma and demonstrate the importance of analyzing risk by NHL histologic type.

Hyperspectral imaging using RGB color for foodborne pathogen detection

This paper reports the development of a spectral reconstruction technique for predicting hyperspectral images from RGB color images and classifying food-borne pathogens in agar plates using reconstructed hyperspectral images. The six representative non-O157 Shiga-toxin producing Escherichia coli (STEC) serogroups (O26, O45, O103, O111, O121, and O145) grown on Rainbow agar plates were used for the study. A line-scan pushbroom hyperspectral imaging spectrometer was used to scan full reflectance spectra of pure non-O157 STEC cultures in the visible and near-infrared spectral range from 400 to 1000 nm. RGB color images were generated by simulation from hyperspectral images. Polynomial multivariate least-squares regression analysis was used to reconstruct hyperspectral images from RGB color images. The mean R-squared value for hyperspectral image reconstruction was ∼0.98 in the spectral range between 400 and 700 nm for linear, quadratic, and cubic polynomial regression models. The accuracy of the hyperspectral image classification algorithm based on k-nearest neighbors algorithm of principal component scores was validated to be 92% with the test set (99% with the original hyperspectral images). The results of the study suggested that color-based hyperspectral imaging would be feasible without much loss of prediction accuracy compared to true hyperspectral imaging.

Next-Generation Models for Evaluation of the Flow Number of Asphalt Mixtures

AbstractThis paper presents the development of next-generation prediction models for the flow number of dense asphalt–aggregate mixtures via an innovative machine learning approach. New nonlinear models were developed to predict the flow number using two robust machine learning techniques, called linear genetic programming (LGP) and artificial neural network (ANN). The flow number of Marshall specimens was formulated in terms of percentages of coarse aggregate, filler, bitumen, air voids, voids in mineral aggregate, and Marshall quotient. An experimental database containing 118 test results for Marshall specimens was used for the development of the models. Validity of the models was verified using parts of laboratory data that were not involved in the calibration process. The statistical measures of coefficient of determination, coefficient of efficiency, root-mean squared error, and mean absolute error were used to evaluate the performance of the models. Further, a multivariable least-squares regression ...

Prediction of crude protein and neutral detergent fibre concentration in residues of in situ ruminal degradation of pasture samples by near-infrared spectroscopy (NIRS)

An important constraint of in situ degradability studies is the need to analyse a high number of samples and often with insufficient amount of residue, especially after the longer incubations of high-quality forages, that impede the study of more than one nutritional component. Near-infrared spectroscopy (NIRS) has been established as a reliable method for predicting composition of many entities, including forages and other animal feedstuffs. The objective of this work was to evaluate the potential of NIRS for predicting the crude protein (CP) and neutral detergent fibre (NDF) concentration in rumen incubation residues of permanent and sown temperate pastures in a vegetative stage. In situ residues (n = 236) from four swards were scanned for their visible-NIR spectra and analysed for CP and NDF. Selected equations developed by partial least-squares multivariate regression presented high coefficients of determination (CP = 0.99, NDF = 0.95) and low standard errors (CP = 4.17 g/kg, NDF = 7.91 g/kg) in cross-validation. These errors compare favourably to the average concentrations of CP and NDF (146.5 and 711.2 g/kg, respectively) and represent a low fraction of their standard deviation (CP = 38.2 g/kg, NDF = 34.4 g/kg). An external validation was not as successful, with R2 of 0.83 and 0.82 and a standard error of prediction of 14.8 and 15.2 g/kg, for CP and NDF, respectively. It is concluded that NIRS has the potential to predict CP and NDF of in situ incubation residues of leafy pastures typical of humid temperate zones, but more robust calibrations should be developed.

Modeling of Swelling Behaviors of Acrylamide-Based Polymeric Hydrogels by Intelligent System

Hydrogels based on acrylamide (AAm) were synthesized by free radical polymerization in an aqueous solution using N,N’-methylenebisacrylamide (MBAAm) as crosslinker. To obtain anionic hydrogels, 2-acrylamido-2-methylpropanesulfonic acid sodium salt (AMPS) and acrylic acid (AAc) were used as comonomers. The swelling behaviors of all hydrogel systems were modeled using an artificial neural network (ANN) and compared with a multivariable least squares regression (MLSR) model and phenomenal model. The predictions from the ANN model, which associated input parameters, including the amounts of crosslinker (MBA) and comonomer, and swelling values with time, produce results that show excellent correlation with experimental data. The parameters of swelling kinetics and water diffusion mechanisms of the hydrogels were calculated using the obtained experimental data. Model analysis indicated that the ANN models could accurately describe complex swelling behaviors of highly swellable hydrogels.

The effect of lifetime fluoridation exposure on dental caries experience of younger rural adults

The aim of this study was to confirm whether the level of lifetime fluoridation exposure is associated with lower dental caries experience in younger adults (15-46 years). Data of the cohort born between 1960 and 1990 residing outside Australia's capital cities from the 2004-2006 Australian National Survey of Adult Oral Health were analysed. Residential history questionnaires were used to determine the percentage of each person's lifetime exposure to fluoridated water (<50%/50+%). Examiners recorded decayed, missing and filled permanent teeth (DMFT). Socio-demographic variables, periodontal risk factors, and access to dental care were included in multivariable least-squares regression models. In bivariate analysis, the higher level of fluoridation category had significantly lower DMFT (mean 6.01 [SE=0.62]) than the lower level of fluoridation group (9.14 [SE=0.73] p<0.01) and lower numbers of filled teeth (4.08 [SE=0.43], 7.06 [SE=0.62], p<0.01). In multivariate analysis, the higher number of full-time equivalent dentists per 100,000 people was associated with a lower mean number of missing teeth (regression coefficient estimate=-1.75, p=0.03), and the higher level of water fluoridation with a lower mean DMFT (-2.45, p<0.01) and mean number of filled teeth (-2.52, p<0.01). The higher level of lifetime fluoridation exposure was associated with substantially lower caries experience in younger rural adults, largely due to a lower number of filled teeth.