Natural Log Transformation Research Articles

Relationship between free and total malondialdehyde, a well-established marker of oxidative stress, in various types of human biospecimens.

Oxidative stress is involved in thoracic diseases and health responses to air pollution. Malondialdehyde (MDA) is a well-established marker of oxidative stress, but it may be present in unconjugated and conjugated forms. To our knowledge, no studies have conducted a systemic evaluation of both free MDA (unconjugated MDA) and total MDA (the sum of both unconjugated and conjugated MDA) across various types of human biospecimens. Free MDA and total MDA were simultaneously measured in a range of human biospecimens, including nasal fluid (N=158), saliva (N=158), exhaled breath condensate (N=40), serum (N=232), and urine (N=429). All samples were analyzed using an HPLC-fluorescence method with high sensitivity and specificity. Due to the right skewed distribution of free MDA and total MDA, we performed natural-log transformation before subsequent statistical analyses. The relationship between the natural log of free and total MDA was evaluated by R2 of simple linear regression. T test was used for comparisons of means between two groups. One-way analysis of variance was used in combination with Tukey's test to compare the natural log of the ratio of free MDA to total MDA across various types of biospecimens. For exhaled breath condensate, serum, urine, nasal fluid and saliva samples, the R2 between free and total MDA were 0.61, 0.22, 0.59, 0.47 and 0.06, respectively; the medians of the free MDA to total MDA ratio were 48.1%, 17.4%, 9.8%, 5.1% and 3.0%, respectively; the free MDA to total MDA ratio in EBC > serum > urine > nasal fluid > saliva (P<0.001 for pairwise comparisons). For exhaled breath condensate and urine samples, using either free or total MDA can provide information regarding the level of oxidative stress; however, that is not the case for serum, nasal fluid, and saliva given the low correlations between free and total MDA.

Tumor Necrosis Factor‐alpha, TNFR1, and TNFR2 Responses to Exercise in the Heat

Plasma levels of Tumor Necrosis Factor‐alpha (TNF‐α) have been shown to increase in response to exercise in hot environments, however, the effects of exercise in the heat on surface expression of TNF receptors (TNFR) 1 and 2 have not been investigated.OBJECTIVETo observe the effects of moderate‐ and high‐intensity exercise in the heat on circulating TNF‐α and surface expression of TNFR1 and TNFR2 on human classical monocytes (CD14++CD16–).METHODSEight recreationally active Caucasian men (24.8 ± 3.0 yrs; 179.8 ± 7.4 cm; 84.4 ± 2.9 kg; 46.8 ± 5.9 ml·kg−1·min−1) completed four exercise trials. The first trial consisted of a VO2max assessment, conducted on a cycle ergometer, while the remaining trials were completed in three environmental conditions: high temperature/low humidity (HTLH; 35°C, 20% RH); high temperature/moderate humidity (HTMH; 35°, 45% RH); and moderate temperature/moderate humidity (MTMH; 22°C; 45%RH). The exercise protocol consisted of a 60‐minute cycling trial at 60% of their previously determined VO2max, a 15‐minute rest period, and a time to exhaustion trail at 90% VO2max (TTE). Blood samples were obtained before (T1) and after (T2) the 60‐minute trial; immediately after TTE (T3), and one hour post‐TTE (T4). Plasma concentrations of TNF‐α were measured via commercially available ELISA. TNFR1 and TNFR2 expression was measured on a subset of participants (n= 5) using flow cytometry. Natural log (LN) transformation was used on non‐normally distributed data and area under the curve (AUC) was calculated using the standard trapezoidal technique. Changes were analyzed using a two factor (time × trial) within‐subjects repeated measures ANOVA and one‐way repeated measures ANOVA.RESULTSA significant interaction was observed for circulating TNF‐α (F= 3.912, p = 0.034, η2p = 0.358). During HTLH, TNF‐α increased from T1 to T2 (p = 0.026) and T3 (p = 0.036), and decreased from T3 to T4 (p = 0.036). During HTMH, TNF‐α increased from T1 to T2 (p = 0.002), T3 (p = 0.006), and T4 (p = 0.011). No significant time effect was observed during MTMH (p &gt; 0.05). Circulating TNF‐α at T1 was significantly lower during HTMH compared to MTMH (p = 0.040). No significant main effect of trial (F= 1.906, p = 0.185, η2p = 0.214) was observed for TNF‐α AUC. No significant interaction (F= 1.422, p = 0.247, η2p = 0.262), nor main effects of time (F= 0.465, p = 0.712, η2p = 0.104) or trial (F= 1.165, p = 0.360, η2p = 0.226) were observed for TNFR1 expression. Additionally, no significant main effect of trial (F= 1.681, p = 0.246, η2p = 0.296) was observed for TNFR1 AUC. No significant interaction (F= 0.998, p = 0.449, η2p = 0.200), nor main effects of time (F= 0.205, p = 0.681, η2p = 0.049) or trial (F= 1.659, p = 0.250, η2p = 0.293) were observed for TNFR2 expression. Additionally, no significant main effect of trial (F= 1.411, p = 0.299, η2p = 0.261) was observed for TNFR2 AUC.CONCLUSIONSModerate‐ and high‐intensity exercise in hot conditions elicits an increase in plasma TNF‐α concentrations, though moderate temperature does not. Furthermore, the environmental condition during exercise did not affect TNFR1 and TNFR2 expression on classical monocytes.Support or Funding InformationThis study was partially funded by the Kent State University Research CouncilThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Air, hand wipe, and surface wipe sampling for Bisphenol A (BPA) among workers in industries that manufacture and use BPA in the United States

ABSTRACTFor decades, bisphenol A (BPA) has been used in making polycarbonate, epoxy, and phenolic resins and certain investment casting waxes, yet published exposure data are lacking for U.S. manufacturing workers.In 2013–2014, BPA air and hand exposures were quantified for 78 workers at six U.S. companies making BPA or BPA-based products. Exposure measures included an inhalable-fraction personal air sample on each of two consecutive work days (n = 146), pre- and end-shift hand wipe samples on the second day (n = 74 each), and surface wipe samples (n = 88). Potential determinants of BPA air and end-shift hand exposures (after natural log transformation) were assessed in univariate and multiple regression mixed models.The geometric mean (GM) BPA air concentration was 4.0 µg/m3 (maximum 920 µg/m3). The end-shift GM BPA hand level (26 µg/sample) was 10-times higher than the pre-shift level (2.6 µg/sample). BPA air and hand exposures differed significantly by industry and job. BPA air concentrations and end-shift hand levels were highest in the BPA-filled wax manufacturing/reclaim industry (GMAir = 48 µg/m3, GMHand-End = 130 µg/sample) and in the job of working with molten BPA-filled wax (GMAir = 43 µg/m3, GMHand-End = 180 µg/sample), and lowest in the phenolic resins industry (GMAir = 0.85 µg/m3, GMHand-End = 0.43 µg/sample) and in the job of flaking phenolic resins (GMAIR = 0.62 µg/m3, GMHand-End = 0.38 µg/sample). Determinants of increased BPA air concentration were industry, handling BPA containers, spilling BPA, and spending ≥50% of the shift in production areas; increasing age was associated with lower air concentrations. BPA hand exposure determinants were influenced by high values for two workers; for all other workers, tasks involving contact with BPA-containing materials and spending ≥50% of the shift in production areas were associated with increased BPA hand levels. Surface wipe BPA levels were significantly lower in eating/office areas (GM = 9.3 µg/100 cm2) than in production areas (GM = 140 µg/100 cm2).In conclusion, worker BPA exposure was associated with tasks and conditions affecting both inhalation and dermal exposure. The potential for BPA-related health effects among these workers is unknown.

An analytical approach to reduce between-plate variation in multiplex assays that measure antibodies to Plasmodium falciparum antigens

BackgroundAntibodies play an important role in immunity to malaria. Recent studies show that antibodies to multiple antigens, as well as, the overall breadth of the response are associated with protection from malaria. Yet, the variability and reliability of antibody measurements against a combination of malarial antigens using multiplex assays have not been well characterized.MethodsA normalization procedure for reducing between-plate variation using replicates of pooled positive and negative controls was investigated. Sixty test samples (30 from malaria-positive and 30 malaria-negative individuals), together with five pooled positive-controls and two pooled negative-controls, were screened for antibody levels to 9 malarial antigens, including merozoite antigens (AMA1, EBA175, MSP1, MSP2, MSP3, MSP11, Pf41), sporozoite CSP, and pregnancy-associated VAR2CSA. The antibody levels were measured in triplicate on each of 3 plates, and the experiments were replicated on two different days by the same technician. The performance of the proposed normalization procedure was evaluated with the pooled controls for the test samples on both the linear and natural-log scales.ResultsCompared with data on the linear scale, the natural-log transformed data were less skewed and reduced the mean–variance relationship. The proposed normalization procedure using pooled controls on the natural-log scale significantly reduced between-plate variation.ConclusionsFor malaria-related research that measure antibodies to multiple antigens with multiplex assays, the natural-log transformation is recommended for data analysis and use of the normalization procedure with multiple pooled controls can improve the precision of antibody measurements.

A Method to Create Body Sizing Systems

Literature reviews show that consumers are not satisfied with the fit of garments sold in stores, primarily due to outdated sizing systems used by companies and the limited number of sizes being produced. The purpose of this article is to present a sizing system creation method, which can be applied on body measurement data to improve the overall fit of garments. Data from the SizeUSA study was used. The sizing system creation process included natural log-transformation, principle component analysis, multivariate linear regression, size range determination, and measurements calculation. The created sizing system was then compared with ASTM D5585-11e1. Analysis of the results showed that the method used to create the sizing system was reliable and repeatable. This was an important research effort for apparel manufactures, as it demonstrated a method to create a sizing system that is flexible and can be altered to fit target consumer groups!

The Relationship Between Changes In Rmssd And Rectus Femoris Cross-sectional Area Following Exercise

PURPOSE: The natural log transformation of the root mean square of successive R-R differences (lnRMSSD) is a parasympathetic measure of heart rate variability. The extent to the relationship between lnRMSSD and localized muscle damage following exercise is unknown..The purpose of this study was to examine the relationship between lnRMSSD and Rectus femoris CSA (CSA-RF) following an exhaustive bout of exercise over 72 hours. METHODS: Twelve participants were measured for pre-exercise lnRMSSD for five minutes in a seated position, followed by a CSA-RF measurement with musculoskeletal ultrasound 15 cm above the superior pole of the participant’s right patella. Next participants completed an exhaustive exercise protocol. Finally, participants repeated the lnRMSSD and CSA-RF measures immediately following exercise termination with follow-up testing at 24-hours, 48-hours, and 72-hours. RESULTS: Repeated measures ANOVA revealed significant differences in lnRMSSD between pre-exercise and post-exercise measures (p = .002, Table 1), but no other significant differences. Likewise, there were significant differences in CSA-RF from pre-exercise to post-exercise (p < .001, Table 1), but no other differences were noted. There was a large near-significant correlation between the changes in lnRMSSD and CSA-RF from pre-exercise to post-exercise (r = -.57, p = .055), and large statistically significant correlation between the changes in lnRMSSD and CSA-RF from pre-exercise measures to 24-hour follow-up (r = -.64, p = .025). CONCLUSIONS: In this study lnRMSSD declined as CSA-RF increased immediately following exercise up to 24 hours. This inverse relationship is likely the result of vagal tone suppression and increased sympathetic outflow in cardiac control during and immediately following exercise. Tracking lnRMSSD following exercise may give practitioners further insight to the mechanisms of recovery.Table: No title available.

Heart Rate Variability Following a Short and Long Bout of High-Intensity Functional Training

Depression of Heart Rate Variability (HRV) occurs following exercise and is influenced by the intensity and duration of the activity. High-Intensity Functional Training (HIFT) is a style of training performed using various modalities and durations. PURPOSE: To examine the effect of a short (<5-min) and a long (15-min) bout of HIFT on HRV recovery. METHODS: Ten apparently healthy males (28 ± 5 yrs) participated in this study. Two HIFT sessions were performed in a crossover fashion. Each visit consisted of three HRV recordings: at rest (PRE; 10-min), post exercise (P; 45-min), and two-hours post (P2HR; 10-min). The short bout (SHORT) consisted of 30 power clean-and-jerks (61 kg) for time, while the long bout (LONG) was a 15-min circuit of 250m row, 20 kettlebell swings (24 kg), and 15 dumbbell squat presses (16 kg). The HRV marker used was the Root Mean Square of Successive Differences (RMSSD) and was analyzed in 5-min segments: the last 5-minutes of PRE, eight segments during P (P1-P8) starting at the 5th minute, and the last 5-mins of P2HR. RESULTS: Normality was violated and data underwent a natural log transformation (lnRMSSD). Repeated Measures ANOVA did not reveal any significant differences in lnRMSSD between the SHORT and LONG trials (p = 0.822). A significant time effect (p = 0.023) was observed in both trials, with lnRMSSD depression occurring from P1-P8 (p < 0.05) and recovering by P2HR (p = 0.141). CONCLUSION: This study indicates that SHORT and LONG bouts of HIFT result in similar HRV depression and recovery. Future research is needed to better understand various bouts of HIFT and its relationship with HRV.

Cross-sectional study of social behaviors in preschool children and exposure to flame retardants

BackgroundChildren are exposed to flame retardants from the built environment. Brominated diphenyl ethers (BDE) and organophosphate-based flame retardants (OPFRs) are associated with poorer neurocognitive functioning in children. Less is known, however, about the association between these classes of compounds and children’s emotional and social behaviors. The objective of this study was to determine if flame retardant exposure was associated with measurable differences in social behaviors among children ages 3–5 years.MethodsWe examined teacher-rated social behaviors measured using the Social Skills Improvement Rating Scale (SSIS) and personal exposure to flame retardants in children aged 3–5 years who attended preschool (n = 72). Silicone passive samplers worn for 7 days were used to assess personal exposure to 41 compounds using gas chromatography-mass spectrophotometer. These concentrations were then summed into total BDE and total OPFR exposure prior to natural log transformation. Separate generalized additive models were used to evaluate the relationship between seven subscales of the SSIS and lnΣBDE or lnΣOPFR adjusting for other age, sex, adverse social experiences, and family context.ResultsAll children were exposed to a mixture of flame retardant compounds. We observed a dose dependent relationship between lnΣOPFR and two subscales where children with higher exposures were rated by their preschool teachers as having less responsible behavior (p = 0.07) and more externalizing behavior problems (p = 0.03). Additionally, children with higher lnΣBDE exposure were rated by teachers as less assertive (p = 0.007).ConclusionsWe observed a cross-sectional association between children’s exposure to flame retardant compounds and teacher-rated social behaviors among preschool-aged children. Children with higher flame retardant exposures exhibited poorer social skills in three domains that play an important role in a child’s ability to succeed academically and socially.

Abstract P045: The Association Between Cigarette Smoking and Cardiovascular Inflammation: The Genetic Epidemiology Network of Arteriopathy Study

Background: To assist in the regulation of novel and existing tobacco products, there is a need to identify biomarkers of early cardiovascular damage following tobacco exposure. Our prior work suggests that inflammatory markers, in particular high-sensitivity C-reactive protein (hsCRP), may be sensitive markers of tobacco mediated cardiovascular damage. We aimed to further study the association of smoking and inflammation in a cohort with hsCRP and 11 other measures of inflammation associated with cardiovascular disease (CVD) risk. Methods: We conducted a cross-sectional analysis on 2,550 siblings diagnosed with essential hypertension prior to age 60 years. Cigarette smoking was assessed by status, intensity, pack-years, and time since quitting. We modeled each biomarker per standard deviation after natural log transformation and evaluated the association between smoking and biomarkers using generalized estimating equations (GEE) to account for intra-familial correlations. Models were adjusted for demographics and CVD risk factors. Results: The mean age of participants was 61±10 years; 64.5% were women and 54.4% African American. There were 12.2% current smokers and 32.2% former smokers. Compared to never smokers, current smokers had significantly higher levels of 8 inflammatory biomarkers ( Table ). In analyses of other smoking variables, there was a consistent association with hsCRP but not other biomarkers. HsCRP was positively associated with pack-years of cigarette smoked and inversely associated with time since quitting, but not with smoking intensity. There was a significant difference in hsCRP levels among current smokers by race ( p for interaction=0.005). On average, hsCRP was higher among African American [0.445 (0.283, 0.606)] compared to White smokers [0.183 (0.011, 0.356)]. Conclusion: Biomarkers of inflammation, especially hsCRP, may allow for early detection of cardiovascular injury due to cigarette smoking and could be useful for the study and regulation of emerging tobacco products.

A longitudinal study of atrazine and 2,4-D exposure and oxidative stress markers among iowa corn farmers.

Reactive oxygen species, potentially formed through environmental exposures, can overwhelm an organism's antioxidant capabilities resulting in oxidative stress. Long-term oxidative stress is linked with chronic diseases. Pesticide exposures have been shown to cause oxidative stress in vivo. We utilized a longitudinal study of corn farmers and non-farming controls in Iowa to examine the impact of exposure to the widely used herbicides atrazine and 2,4-dichlorophenoxyacetic acid (2,4-D) on markers of oxidative stress. 225 urine samples were collected during five agricultural time periods (pre-planting, planting, growing, harvest, off-season) for 30 farmers who applied pesticides occupationally and 10 controls who did not; all were non-smoking men ages 40-60. Atrazine mercapturate (atrazine metabolite), 2,4-D, and oxidative stress markers (malondialdehyde [MDA], 8-hydroxy-2'-deoxyguanosine [8-OHdG], and 8-isoprostaglandin-F2α [8-isoPGF]) were measured in urine. We calculated β estimates and 95% confidence intervals (95%CI) for each pesticide-oxidative stress marker combination using multivariate linear mixed-effect models for repeated measures. Farmers had higher urinary atrazine mercapturate and 2,4-D levels compared with controls. In regression models, after natural log transformation, 2,4-D was associated with elevated levels of 8-OHdG (β = 0.066, 95%CI = 0.008-0.124) and 8-isoPGF (β = 0.088, 95%CI = 0.004-0.172). 2,4-D may be associated with oxidative stress because of modest increases in 8-OHdG, a marker of oxidative DNA damage, and 8-isoPGF, a product of lipoprotein peroxidation, with recent 2,4-D exposure. Future studies should investigate the role of 2,4-D-induced oxidative stress in the pathogenesis of human diseases. Environ. Mol. Mutagen. 58:30-38, 2017. © 2016 Wiley Periodicals, Inc.

Resting cardiac autonomic activity and body composition following a 16-week high-intensity functional training intervention in women: A pilot study

High-Intensity Functional Training (HIFT) is an increasingly popular mixed modal high-intensity training style with little empirical evidence regarding adaptations. The objective of this study was to examine alterations in resting cardiac autonomic activity through the measurement of heart rate variability (HRV) and body composition in women following 16-weeks of HIFT. Nine apparently healthy females (35.8 ± 9.3 years old) participated in this study. Resting heart rate (RHR), HRV, and body composition measures were collected pre and post 16-weeks of the HIFT intervention. The markers of HRV used were the Root Mean Square of Successive Differences (RMSSD) and High-Frequency (HF) power. Body composition markers used were body fat percentage (BF%) and body mass (BM). A natural log transformation (ln) was applied to HRV markers prior to analysis. Paired sample t-test showed significant reductions in post RHR (p = 0.018) and BF% (p = 0.012). However, no significant changes were observed in post lnRMSSD (p = 0.501), lnHF (p = 0.760), or BM (p = 0.285). 16-weeks of HIFT was not sufficient to alter makers of HRV. Importantly, the participation in 16-weeks of HIFT elicited improvements in basic health measures (RHR and BF%) in recreationally active females.

Association of Leukocyte Telomere Length and Mitochondrial DNA Copy Number in Children from Salamanca, Mexico.

The purpose of this study was to determine if there is a correlation between telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) in children. Leukocyte TL and mtDNAcn were measured by real-time PCR in 98 Mexican children 6-12 years of age from Salamanca, México. A positive association was found between TL and mtDNAcn after a natural log transformation (Pearson correlation r = 0.72; p < 0.0001). No correlation between age and body mass index (BMI) biomarkers was found, and no differences according to sex were observed. After adjustment for these variables, a linear regression model showed an association between TL and mtDNAcn (β = 0.739, 95% confidence interval 0.594; 0.885, p < 0.0001). A strong positive correlation between TL and mtDNAcn was found in the study population; age, sex, and BMI seemed to have no effect on this correlation.

Response surface methodology for optimization of stabilizer dosage rates of marginal sand stabilized with Sludge Ash and fiber based on UCS performances

Optimization of the stabilization materials in terms of their dosage rates specifically used for stabilization applications have become a great interest by the experimenters due to the concerns of strength performance, time and economy for the construction projects. Using a relatively recent optimization technique, Response Surface Methodology (RSM), this paper is mainly focused on investigation of the optimum amounts of stabilizers (Sewage Sludge Ash (SSA) and Polypropylene Fiber (PF)) and Curing Time (CT) that yield to maximum unconfined compressive strength (UCS) for stabilization of a marginal sand (poorly-graded sand). For this purpose, an experimental study has been carried out conducting UCS tests, where the stabilizer proportions are 0-30% for SSA and 0-1% for PF, by total dry weight of sand+SSA. Also, the curing times considered prior to testing are 0, 7 and 14 days. All UCS tests have been performed following the experimental program by central composite design that used the ranges of stabilizer proportions and curing times. On the basis of experimental data, a full quadratic model with natural log transformation and backward analysis has been built through RSM considering the factors of SSA, PF, CT, and the response of UCS. The results indicate that the mathematical model built in this study is statistically significant (p ≤ 0.05) through the analysis of variance (ANOVA), thus it is applicable for optimization process. The findings from the optimization effort demonstrate that the most potential values for SSA, PF and CT are 19.95%, 0.57% and 12.15-day, respectively. The proposed values could be beneficial for the experimenters in practice specifically for preliminary evaluations prior testings of stabilizations.

Adult and child urinary 2,4-D in cities with and without cosmetic pesticide bylaws: a population-based cross-sectional pilot study.

We evaluated 2,4-dichlorophenoxyacetic acid (2,4-D) exposure in four municipalities with and without cosmetic pesticide bylaws in British Columbia, Canada. We recruited a child (aged 1.5-5 years) and adult from 10 households in each city, who provided urine samples in May and June, 2009. No households had used pesticides for 7 days prior to sample collection. We quantified urinary 2,4-D using LC/MS/MS. Quantities of 2,4-D in urine were similar across cities and below biomonitoring equivalents corresponding to references doses in the United State of America and Canada. When adult's and children's urines were analyzed together in linear mixed-effects regression models, natural log urinary 2,4-D was significantly associated with having a diet of ⩾50% organic food (β=-0.6 (0.3) μg/l, P=0.05). Without natural log transformation, median concentration of urinary 2,4-D among those who ate ⩾50% organic food (n=12) was 1.4 μg/l versus 1.5 μg/l for others (n=59). Lack of a significant association (two-sided alpha=0.05) between pesticide bylaws and urinary 2,4-D might reflect small sample size, lack of recent acute exposure, or that 2,4-D exposure is primarily influenced by sources of exposure not addressed through bylaws. Food might be a route of exposure to 2,4-D, consistent with other studies. Future research will require larger sample sizes for sufficient statistical power.

Adult and child urinary 2,4-D in cities with and without cosmetic pesticide bylaws: a population-based cross-sectional pilot study

We evaluated 2,4-dichlorophenoxyacetic acid (2,4-D) exposure in four municipalities with and without cosmetic pesticide bylaws in British Columbia, Canada. We recruited a child (aged 1.5-5 years) and adult from ten households in each city, who provided urine samples in May and June, 2009. No households had used pesticides for seven days prior to sample collection. We quantified urinary 2,4-D using LC/MS/MS. Quantities of 2,4-D in urine were similar across cities and below biomonitoring equivalents corresponding to references doses in the USA and Canada. When adult’s and children’s urines were analyzed together in linear mixed-effects regression models, natural log urinary 2,4-D was significantly associated with having a diet of ≥50% organic food (β=-0.6 (0.3) μg/L, p=0.05). Without natural log transformation, median concentration of urinary 2,4-D among those who ate ≥50% organic food (n=12) was 1.4 μg/L versus 1.5 μg/L for others (n=59). Lack of a significant association (two-sided alpha=0.05) between pesticide bylaws and urinary 2,4-D might reflect small sample size, lack of recent acute exposure, or that 2,4-D exposure is primarily influenced by sources of exposure not addressed through bylaws. Food might be a route of exposure, consistent with other studies. Future research will require larger sample sizes.

Using a three-axis accelerometer to identify and classify sheep behaviour at pasture

Identifying and classifying feeding behaviour in free-ranging ruminants will help improve efficiency of animal production. Another potential benefit would be in understanding the role behaviour has in determining heritability of methane measurement. The aim of this study was to determine the accuracy, sensitivity, specificity and precision with which tri-axial accelerometers can identify sheep behaviour at pasture. Two studies, the first over six days and the other over two days were conducted using South African Meat Merino×Merino ewes averaging 55 (±5)kg and 22 months of age, respectively. The animals were located in either a semi-improved pasture (0.3ha) or in a small (30m2) area with access to water to observe five mutually exclusive behaviours, grazing, lying, running, standing and walking. A tri-axial accelerometer was attached to a halter on the under-jaw of each animal. Three epochs (3s, 5s and 10s) with forty-four features calculated from acceleration signals were used to classify behaviours. The five most important features for each epoch were determined using random forest and the five behaviours were classified using a decision-tree algorithm to determine model accuracy, sensitivity, specificity and precision. The decision-tree algorithm correctly classified 90.5, 92.5 and 91.3% of the evaluation data set for grazing behaviour for the 3, 5 and 10s epochs, respectively. There was no difference in the accuracy between the evaluation and validation data sets for grazing behaviour at each epoch. The model predicted grazing and running behaviour highly accurately and with the highest precision, sensitivity and specificity for the validation data set for the 10s epoch. The 5s epoch for both the evaluation and validation data sets was selected as the most suitable epoch based on the Kappa values. We successfully identified from the distribution of component populations that the natural log-transformation of the mean of X-axis accelerations for each epoch could identify grazing and non-grazing states. Therefore, this methodology will be useful in identifying sheep activity for research applications such as before methane measurement using portable accumulation chambers or other applications addressing temporal grazing patterns.

Cardiac autonomic modulation and blood pressure responses to isometric handgrip and submaximal cycling exercise in individuals with down syndrome.

Individuals with Down syndrome (DS) exhibit autonomic dysfunction, manifested as attenuated heart rate (HR) and blood pressure (BP) responses to sympathoexcitation. Whether a subgroup of individuals with DS with a normal HR response would have normal autonomic responses to sympathoexcitation remains unclear. We compared autonomic modulation using HR variability (HRV) and BP responses in individuals with and without DS (controls) matched for the HR change to isometric handgrip (HG) (10 DS, 8 controls) and submaximal cycling exercise (CE) (9 DS, 9 controls). HG was performed for 2min at 30% of maximal voluntary contraction. CE included two 6-min stages at 0W and at 50% of body weight. Beat-to-beat HR and BP were recorded. HRV variables were natural log transformation (Ln) of low frequency (LF), high frequency (HF), LF/HF ratio, total power (TP), and the root mean square of successive differences (RMSSD). In the HG study, although individuals with DS exhibited an overall lower systolic BP, LF/HF ratio, and LnLF/LnHF, their BP and HRV responses to HG were similar to those of the controls. In the CE study, individuals with DS exhibited lower resting LnLF and an overall lower systolic BP and mean arterial pressure compared with controls. During the CE, individuals with DS exhibited an increased diastolic BP and a smaller reduction in LnTP than controls. These differences disappeared after controlling for confounders. Our results suggest that despite normal HR responses to sympathoexcitatory tasks, HRV was largely similar to controls, with some evidence of autonomic dysfunction in individuals with DS.

Modeling and Optimization of Friction and Wear Characteristics of Ti3Al2.5V Alloy Under Dry Sliding Condition

Modeling of dry sliding friction and wear behavior of Ti3Al2.5V alloy sliding against EN31 steel using a multi-tribotester has been presented. Mathematical model equations in the form of natural log transformation for wear rate (WR), average coefficient of friction (μa), and a square root transformation for maximum contact temperature (Tm) considering the effect of tribological variables have been developed and validated by comparing them with the experimental results. The authors claim novelty with regard to modeling and optimization of friction and wear characteristics of Ti-3Al2.5V alloy. The results reveal that the magnitude of wear rate and maximum contact temperature increases with increase in sliding velocity and increasing normal load with few exceptions. Whereas average coefficient of friction first increases with increasing sliding velocity up to 2.51 m/s, and then decreases at highest sliding velocity. The load is found to have strongest influence on both wear rate and average coefficient of friction followed by sliding velocity, whereas sliding velocity has strongest influence on the maximum contact temperature followed by load. The perturbation plot results are also in accordance with the analysis of variance (ANOVA) analysis. The theoretical and experimental results have an average error of 5.06%, 1.78%, and 1.42%, respectively, for wear rate, average coefficient of friction, and maximum contact temperature. Optimization resulted in a maximum desirability of 0.508 at a load of 60 N and a sliding velocity of 1.5 m/s. For these values, the predicted minimum wear rate is 0.0001144 g/m, the coefficient of friction is 0.3181, and the tool-tip temperature is 59.03 °C.

Normal limits for serum thyrotropin vary greatly depending on method.

Thyroid-stimulating hormone (TSH) levels within populations do not follow Gaussian distribution, and normal limits are derived after mathematical normalization. The clinical relevance of these limits is unknown. The objective of this study was to compare upper and lower TSH limits by four data normalization methods with non-normalized data and assess their clinical relevance. Results of blood samples taken by community physicians and stored in a computerized database were analysed after removing samples from patients with evidence of thyroid illness. TSH values were normalized by the Hoffmann and Tukey methods and each method with natural log transformation. Non-normalized data for TSH in the uppermost and lowermost percentile were also calculated. Clinical relevance was determined by alterations in thyroid hormone levels at, below and above the limits for each method. The maximal reduction from non-normalized data for the upper normal limit (UNL) was by the Hoffman method 43% = 3·1 mIU/l). The maximal increase for the lower normal limit (LNL) was also by the Hoffman method (708% = 0·81 mIU/l). There was very limited difference in average FT3 and FT4 between patients with TSH within, below or above the normal range for all methods. Different normalization methods alter the normal limits greatly. However, in individuals without thyroid illness, thyroid hormone values are stable over a wide range of TSH levels including beyond the UNL for all methods. Indeed, there may be no true universal upper TSH cut-off level and clinical decision-making cannot rely on these calculated limits.

A meta-analysis of milk production responses to increased net energy intake in Scandinavian dairy cows

The objectives of this analysis were to develop empirical prediction models for milk yield based on cow characteristics and dry matter intake (DMI) or net energy intake (NEL) and to evaluate the effect of breed, parity, stage of lactation and the additional prediction value of using NEL estimates versus DMI estimates for incorporation in future economical optimization models of the energy level in dairy cow rations. Previous Danish response models are outdated due to higher yield capacity of cows and the use of the new Nordic feed evaluation system NorFor since 2011. A data set with 195 treatment mean observations was compiled from original data of 13 trials from Denmark, Norway and Sweden representing the breeds Danish Holstein, Danish Red, Danish Jersey, Norwegian Red and Swedish Red. Total data were grouped into 4 sub datasets according to parity; either primiparous or multiparous and according to stage of lactation; either DIM 1 to 100 (Early) or DIM 101 to 200 (Mid). All analyzed ration characteristics were calculated from NorFor principles or estimated from NorFor feed table values. Data were analyzed using linear mixed effects model with trials as random effect. Residuals were weighted by number of cows in each treatment mean. Best fit model was by use of linear and natural log transformation of NEL intake rather than DMI in the regression, especially when also including the ration concentration of the individual nutrients (g/MJ NEL), neutral detergent fibre, amino acids absorbed in the small intestine and crude fat, in the model. Breed specific responses were parallel and only differed by their intercept. In early lactation for multiparous cows with a mean NEL intake (136MJ) the model predicted an ECM response of 35.4kg and for primiparous cows with mean NEL intake (115MJ) the model predicted an ECM response of 27.8kg. Marginal milk response (kg ECM/MJ NEL) decreased more for multiparous cows (from 0.34 to 0.08) than for primiparous cows (from 0.20 to 0.15) within the observation ranges of NEL intake.