Pairwise Comparisons Of Means Research Articles

The relative importance of herbicide use for conservation tillage adoption by U.S. corn and soybean producers.

Herbicide use is widespread in agricultural production to control weeds prior to and after planting and to "burndown" weeds in the spring for conservation tillage. Whether conservation tillage adoption leads to higher herbicide usage has been a question of policy relevance for decades in the United States. Older U.S. studies using standard statistical and economic techniques have not consistently demonstrated higher herbicide usage levels among producers practicing conservation tillage, but these studies did not fully account for other practices, economic, or agronomic factors. To provide a more timely and comprehensive understanding of the importance of herbicides to conservation tillage, this study achieves two objectives with the most recent, nationally representative data from the US Department of Agriculture. First, it describes trends and compares conservation tillage and herbicide usage among field corn and soybean producers, similar to previous studies using standard economic techniques. Second, a Classification and Regression Tree (CART) model is employed-a novel methodology relative to previous studies that offers distinct advantages over traditional regression modeling-to evaluate the importance of herbicide use for conservation tillage adoption while accounting for other factors. Pairwise mean comparisons for field corn and soybeans indicated that herbicide usage pre-emergence was significantly higher with conservation tillage, but there was no consistent, significant differences in herbicide usage post-emergence. The CART analysis (with prediction accuracy ranging from 68-72%) also showed that pre-emergent use of glyphosate was the strongest predictor (with predicted probabilities from 0.83-0.86) of conservation tillage for field corn in 2016 and soybeans in 2018. Other factors such as the use of crop rotations, highly erodible land, region, and farm size were also strong predictors of conservation tillage. These findings highlight the importance and complexity of herbicide use in the adoption of conservation tillage for U.S. field corn and soybeans.

Impact of repeated heat-pressing on the microstructure and flexural strength of lithium disilicate glass-ceramics

BackgroundThe leftover material from the heat-pressing of IPS e.max Press ceramic is often discarded, despite some laboratories exploring its potential for reuse. However, there is a lack of data on the performance of IPS e.max Press ceramic when combined with the button portions. This study investigated the impact of repeated heat-pressing on the crystal structure and flexural strength of lithium disilicate glass-ceramic (LDGC).MethodsSpecimens (N = 30, n = 10 per group) were categorized based on the number of heat-pressing cycles: G0 (control group, no heat-pressing), G1 (one cycle of heat-pressing), and G2 (two cycles of heat-pressing). The crystal structure of LDGC bars was characterized using X-ray diffraction (XRD). Flexural strength was tested, and microstructures were analyzed via scanning electron microscopy (SEM) and the ImageJ processing program. Data were analyzed using one-way analysis of variance (ANOVA), and multiple pairwise comparisons of means were performed with Tukey’s post-hoc test.ResultsG2 exhibited significantly lower flexural strength and crystallinity, as well as larger crystal size, compared to G1 and G0 (p < 0.05). Flexural strength values decreased significantly with an increased number of heat-pressing cycles.ConclusionsThe mechanical properties of LDGC significantly degraded after repeated heat pressing. Therefore, it is not clinically advisable to repeatedly press the lithium disilicate ingot together with the leftover material.

Differences in Mental Illness Stigma by Disorder and Gender: Population-Based Vignette Randomized Experiment in Rural Uganda.

Understanding and eliminating mental illness stigma is crucial for improving population mental health. In many settings, this stigma is gendered, from the perspectives of both the stigmatized and the stigmatizers. We aimed to find the differences in the level of stigma across different mental disorders while considering the gender of the study participants as well as the gender of the people depicted in the vignettes. This was a population-based, experimental vignette study conducted in Buyende District of Eastern Uganda in 2023. We created 8 vignettes describing both men and women with alcohol use disorder, major depressive disorder, generalized anxiety disorder, and schizophrenia consistent with DSM-5 criteria. Participants from 20 villages in rural Buyende District of Uganda (N=379) were first read a randomly selected vignette and administered a survey eliciting their attitudes (Personal Acceptance Scale [PAS] and Broad Acceptance Scale [BAS]) towards the person depicted in the vignette. We used analysis of variance (ANOVA) with Bonferroni-adjusted, empirical p-values to compare levels of acceptance across disorders and genders. Attitudes towards people with mental illness, as measured by the PAS, varied across different mental disorders (p=0.002). In pairwise mean comparisons, the greater acceptance of anxiety disorder vs. schizophrenia was statistically significant (Mean [SD] PAS: 2.91 [3.15] vs 1.62 [1.95], p=0.008). Secondary analyses examining differences in acceptance across gender combinations within mental disorders showed that PAS varied across gender combinations for depression (p=0.017), suggesting that acceptance is higher for women with depression than men with depression. In this population-based vignette study from rural Uganda, we found that people with schizophrenia were less accepted compared to people with anxiety disorders. We also found that there was greater acceptance of women with depression than men with depression. Anti-stigma initiatives may need to be targeted to specific disorders and genders.

Effects of Lesson Study and Team Teaching on Students’ Achievement in Physics in Selected Secondary Schools in Niger State

The study was carried out to examine the effects of Lesson study and Team teaching on students’ achievement in Physics in selected secondary schools in Niger State. The study employed a quasi-experimental (pre-test post-test non-equivalent group design) and was guided by two research questions and two corresponding hypotheses. The population of the study comprised of 34,694 Senior Secondary School II Physics students (20,320 Male, 16,374 Female). 380 students (213 male, 167 Female) in the six purposively sampled science and technical colleges were used for the study. Data was collected from the sampled students using Physics Achievement Test for Students (PATS). The reliability coefficient for PATS was calculated using Pearson Product Moment Correlation (PPMC) and its value given as 0.77. To answer the research questions, mean and standard deviation were used. The corresponding hypotheses were tested using ANOVA at 0.05 decision level. The Tukey procedure was used to make pairwise comparisons of means where necessary. The results revealed that there was a statistically significant difference among the groups taught Physics using Lesson Study model, Team Teaching and Lecture method (F (2,377) = 8.708, p (0.000) &lt; 0.05). A further analysis shows that significant difference exists between the group of students taught using Lesson Study model and those taught using Lecture method (p = 0.000). Another significant difference was also found between the group of students taught using Team Teaching and those taught using Lecture method. However, there was no statistically significant difference between the students taught using Lesson Study and those taught using Team Teaching The male and female in the experimental groups performed better than male and female in the control group F(5,374)=4.517, p (0.001) &lt; 0.05. From the study, it was recommended that Physics teachers should implement Lesson Study for active participation of students towards enhancing students’ achievement in Physics.

237 Evaluation of Thermal Variation During Early-Stage Incubation on Broiler Chicken Pectoralis Major Muscle Satellite Cell Mitotic Activity and Heterogeneity at 28 Days Post-Hatch

Abstract Muscle satellite cells (SC) have an essential role in post-hatch skeletal muscle growth. To evaluate the effects of thermal variation (TV) during early-stage incubation (ESI) on Pectoralis major (PM) muscle SC heterogeneity of broiler chickens reared to 28 d post-hatch a randomized complete block design experiment with a 3 × 2 factorial treatment structure was conducted. Yield Plus × Ross 708 broiler breeder eggs (n = 2,160) ranging from 54 to 59 g were allotted equally by weight into 90-egg trays (n = 4 trays per incubator). All eggs were pre-warmed at 24 °C for 8 h and incubated at 37.5 °C from embryonic day (ED) 0 to 4. From ED 4 to 11, eggs were incubated at 1 of 3 temperatures (n = 2 incubators per TV treatment); 37.5 °C (CTL), 36.4 °C (COLD), or 38.6 °C (HOT). On ED 11, all incubators were returned to the CTL (37.5 °C) set point until ED 18. On ED 18, all eggs were transferred to baskets in hatchers set to 36.7 °C. After 514 h of incubation, all chicks were removed simultaneously, vent sexed, and weighed. Chicks were randomly allotted to floor pens (6 pens per treatment per sex) blocked by location and reared on a common diet. On d 28, birds (n = 10 per TV x sex treatment) were injected with bromodeoxyuridine (BrdU) before PM sample collection. Cryosections were immunofluorescence stained to facilitate taxonomy of SC populations expressing the myogenic regulatory factors Pax7 and MyoD as well as the proliferation marker BrdU by fluorescence microscopy. Data were analyzed as a 2-way ANOVA using SAS PROC GLIMMIX with TV treatment and broiler sex as main effects. Means were separated with the PDIFF option at P ≤ 0.05. Tendencies were declared when 0.0501 ≤ P ≤ 0.10. A TV × sex interaction was observed only for the MyoD+: Pax7+ SC density (P = 0.0232); however, none of the pairwise mean comparisons were significant at P &amp;lt; 0.05. Though CTL male and COLD female chicks had twice the density of MyoD+:Pax7+ SC as CTL females (P = 0.0535) and HOT males (P = 0.0645), respectively. There is no clear explanation for this observation. There were no interactive or main effects on density of MyoD+, Pax7+, MyoD+:BrdU+, Pax7+:BrdU+, MyoD+:Pax7+:BrdU+ SC (P ≥ 0.1258) or nuclear density (P = 0.1017) in 28-d-old broilers. These data suggest that if TV during ESI impacts SC myogenic regulatory factor heterogeneity and mitotic activity in broilers, the effects have concluded by d 28 post-hatch in commercial broilers. Further exploration of earlier time points will be necessary to determine whether the previously observed effects of TV during ESI on growth performance and meat yield are SC-mediated post-hatch.

Short-Term Impact of “Amaka Amasanyufu” Multiple Family Group Intervention on Mental Health Functioning of Children With Disruptive Behavior Disorders in Uganda

We evaluate the mid-intervention (8 weeks) and short-term (16 weeks) impact of a culturally adapted multiple family group (MFG) intervention, "Amaka Amasanyufu," on the mental health of children with disruptive behavior disorders (DBDs) and primary caregivers in Uganda. We analyzed data from the Strengthening mental health and research training in Sub-Saharan Africa (SMART) Africa-Uganda study. Schools were randomized to the following: a control group; an MFG facilitated by parent peers (MFG-PP); or an MFG facilitated by community health workers (MFG:CHW). All participants were blinded to interventions provided to other participants and study hypotheses. At 8 weeks and 16 weeks, we evaluated differences in depressive symptoms and self-concept among children and in mental health and caregiving-related stress among caregivers. Three-level linear mixed-effects models were fitted. Pairwise comparisons of post-baseline group means were performed using the Sidak adjustment for multiple comparisons and standardized mean differences. Data from 636 children with DBDs and caregivers (controls: n= 243, n= 10 schools; MFG-PP: n= 194, n= 8 schools; MFG-CHW: n= 199, n= 8 schools) were analyzed. There were significant group-by-time interactions for all outcomes, and differences were observed mid-intervention, with short-term effects at 16 weeks (end-intervention). MFG-PP and MFG-CHW children had significantly lower depressive symptoms and higher self-concept, whereas caregivers had significantly lower caregiving-related stress and fewer mental health problems, than controls. There was no difference between intervention groups. Amaka Amasanyufu MFG intervention is effective for reducing depressive symptoms and improving self-concept among children with DBDs while reducing parental stress and mental health problems among caregivers. Given the paucity of culturally adapted mental health interventions, this provides support for adaptation and scale-up in Uganda and other low-resource settings. SMART Africa (Strengthening Mental Health Research and Training); https://clinicaltrials.gov/: NCT03081195.

DLK1: A Novel Biomarker of Placental Insufficiency in Stillbirth and Live Birth.

Delta-like homolog 1 (DLK1) is a growth factor that is reduced in maternal sera in pregnancies with small for gestational age neonates. We sought to determine if DLK1 is associated with stillbirth (SB), with and without placental insufficiency. A nested case-control study was performed using maternal sera from a multicenter case-control study of SB and live birth (LB). SB and LB were stratified as placental insufficiency cases (small for gestational age <5% or circulatory lesions on placental histopathology) or normal placenta controls (appropriate for gestational age and no circulatory lesions). Enzyme-linked immunosorbent assay (ELISA) was used to measure DLK1. The mean difference in DLK1 was compared on the log scale in an adjusted linear regression model with pairwise differences, stratified by term/preterm deliveries among DLK1 results in the quantifiable range. In exploratory analysis, geometric means were compared among all data and the proportion of "low DLK1" (less than the median value for gestational age) was compared between groups and modeled using linear and logistic regression, respectively. Overall, 234 SB and 234 LB were analyzed; 246 DLK1 values were quantifiable within the standard curve. Pairwise comparisons of case and control DLK1 geometric means showed no significant differences between groups. In exploratory analysis of all data, adjusted analysis revealed a significant difference for the LB comparison only (SB: 71.9 vs. 99.1 pg/mL, p = 0.097; LB: 37.6 vs. 98.1 pg/mL, p = 0.005). In exploratory analysis of "low DLK1," there was a significant difference between the odds ratio of having "low DLK1" between preterm cases and controls for both SB and LB. There were no significant differences in geometric means nor "low DLK1" between SB and LB. In exploratory analysis, more placental insufficiency cases in preterm SB and LB had "low DLK1." However, low DLK1 levels were not associated with SB. · Maternally circulating DLK1 is correlated with placental insufficiency.. · Maternally circulating DLK1 is not correlated with SB.. · DLK1 is a promising marker for placental insufficiency..

Effect of aqueous environment on wear resistance of dental glass\u2013ceramics

BackgroundWear resistance affects dental ceramics longevity and the functions of the opposing teeth. However, data for the effect of aqueous environment on wear resistance of dental ceramics are lacking. This study evaluated the effect of aqueous environment on wear resistance of typical dental glass–ceramics.MethodsDisk specimens were prepared from lithium disilicate glass–ceramics (LD) and leucite reinforced glass–ceramics (LEU). The disk specimens paired with steatite antagonists were tested in a pin-on-disk tribometer under both wet and dry conditions with 10 N up to 500,000 wear cycles. The wear analysis of glass–ceramics was performed using a 3D profilometer after 100,000, 300,000 and 500,000 wear cycles. Wear morphologies were analyzed by employing scanning electron microscopy (SEM). The crystalline compositions of specimens stored in a dry environment and subsequently immersed in distilled water for 40 h were separately determined using X-ray diffraction (XRD). The chemical states of the wear surfaces for LD were analyzed by X-ray photoelectron spectroscopy (XPS). The data analysis and multiple pair-wise comparisons of means were performed by using one-way analysis of variance (ANOVA) and Tukey’s post-hoc test.ResultsLEU in a wet environment exhibited less wear volume loss than that in a dry environment (p < 0.05). The volume loss of LD in a wet environment was higher than that in a dry environment (p < 0.05). The wear volumes of steatite antagonists paired with two glass–ceramics under dry conditions were higher than under wet conditions.ConclusionsXPS spectra of LD under wet conditions indicated that high wear loss might result from the effect of stress corrosion by water and reaction of water with the ionic-covalent bonds at the crack tip. XPS spectra and SEM images of LD under dry conditions showed a possible formation of tribofilm. Within the limitations of this in vitro study, water was wear-friendly to LEU and all opposing steatites but aggravated wear for LD.

131 Pilot: Does Drinking Water Availability Affect Stocker Cattle Grazing Wheat Pasture?

Abstract The objective was to determine if restricting drinking water affects animal performance and hematological responses in cattle grazing high-moisture-content, fresh wheat pasture. Angus-cross steers (n = 10, 411 kg ± 24.5 kg) were randomly assigned to either 100% or 50% of baseline (d -7 to 0) water intake. The design of this experiment was a completely randomized design with 5 replications, with steer as experimental unit. Steers were individually hand-watered 1X per d for the entire experiment (d -7 to 28). Body weight, packed-cell volume (PCV), plasma total solids (PTS), fecal DM (F_DM), eyeball recession score (ERS) and skin turgor score (STS) were recorded from each steer weekly. Forage mass and forage DM were calculated weekly by hand-clipping ten, randomly-located samples using a 0.96-m forage hoop. Data were analyzed using ANOVA methods in SAS v9.4, and pairwise comparisons of means were completed using Fisher’s LSD methods at the nominal 0.05 level of significance. Restricted steers gained less than unrestricted steers (P &amp;lt; 0.01, 1.04 vs. 1.35 kg / d, respectively). Fecal DM percentage did not differ (P = 0.26). There was no difference in PCV (P = 0.15) or PTS (P = 0.27); however PCV and PTS linearly decreased (P &amp;lt; 0.001) from d -7 to 28 for both treatment groups. Eyeball recession score and STS did not differ between treatment groups (P = 0.34). The mean forage mass and forage DM (d -7 to 28) were 2,229 kg per hectare and 24%, respectively. In conclusion, restricting water intake to cattle grazing wheat pasture resulted in lower ADG; however differences in hematological measures of dehydration were not observed in this study.

Comparative studies on Culex bitaeniorhynchus Giles (1901) and its tenax variant (Diptera: Culicidae) in Chandigarh, India

During present investigations the detailed morphotaxonomic studies of Culex bitaeniorhychus revealed that it exists in two forms i.e typical and tenax in and around Chandigarh. Various intraspecific variations in the morphology and male genitalia were observed in both these forms. The main aim of this study is to distinguish these two forms of Cx. bitaeniorhynchus and their separation from other closely related species. The intraspecific variants of these forms have been studied further with respect to phallosome regions of the male genitalia. For assessing the significant differences among their phenotypic characteristics one–way ANOVA was done along with pair-wise comparisons of samples means. Some of the earlier workers have considered tenax form, a synonym of Cx. infula which is another closely related species of Cx. bitaeniorhynchus. But, on the basis of remarkable differences observed between tenax and infula, it is suggested that these two are separate taxons and should not be synonymised.

Factors Associated With Stunting Among Infants and Young Children Aged 7–29 Months in Post-conflict Northern Uganda

ObjectivesTo examine factors associated with stunting in Agago District, Uganda MethodsWe used cross-sectional data from a quantitative baseline survey of 870 households of the ONCE (One Nutrition in Complex Environments) project currently being conducted in Agago district of Uganda. Survey data used include infant anthropometry, infant feeding practices, 24-hour dietary recall, maternal heights, weights, education and household characteristics. Statistical methods include Pearson correlation coefficients, student T-tests, pair-wise mean comparisons with Bonferroni adjustment, and stepwise multivariable linear and logistic regression analyses controlled for clustering. Dependent variables include length-for-age z-score (LAZ, –6 to 6, continuous) and being stunted (binary). Independent variables include child age, child’s birth weight, diarrheal morbidity (past two weeks), maternal education, maternal height, household wealth index, and animal sourced foods consumption (ASF, categorical: no ASF (comparator), 1 ASF, >= 2 ASF). ASF is defined as consumption of dairy, animal flesh, fish of any kind, organ meat, insects, or eggs in previous 24 hours. ResultsInfants between 7 months and 2.5 years with complete data were included (N = 621), of whom 19.7% were classified as stunted. Mean LAZ was –1.05 (SD: 1.24). Most children did not consume any ASF in the past 24 hours (73.6%). ASF consumption was not associated with LAZ (1 kind of ASF: –0.0699, 95% CI: –0.329, 0.189) or stunting (1 kind of ASF OR: 1.186, 95% CI: 0.614, 2.292). Maternal height was associated with 7.8% decreased odds of being stunted (OR: 0.922, 95% CI: 0.878, 0.969); age was associated with 8.9% increased odds of being stunted (OR: 1.089, 95% CI: 1.011, 1.090); birth weight was associated with 54% decreased odds of being stunted (OR: 0.461, 95% CI: 0.296, 0.717). Infants with diarrhea were 96% more likely to be stunted than those without (OR: 1.956, 95% CI: 1.050, 3.642). ConclusionsFactors associated with stunting were maternal height, child age, birth weight and diarrheal morbidity. ASF consumption was not, possibly due to low levels and possibly low frequency of consumption. Mother’s nutritional status is likely to be an important predictor in this population. Funding SourcesFeed the Future Initiative, U.S. Agency for International Development.

The Reliability and Validity of Donor Tissue Biopsies in Lung Transplantation

Purpose During lung transplantation, donor biopsies are collected for histologic and biomarker assessments to understand lung injury. Samples are often taken from a single location and it is unknown whether this is truly representative of the injury across the organ. The objective of this study was to investigate the uniformity of cytokine mRNA expression in tissue samples collected from different locations in donor lungs. Methods Eight unused donor lungs were inflated, flash-frozen in liquid nitrogen, and partitioned into 10 to 15 slices from apex to base. Five 1 cm3 biopsies were taken from each lung; three were consistently taken from the third, sixth, and ninth slices, while two were taken from the lingula and a noted potential injury site. Three pieces of each biopsy were used to measure mRNA expression of IL-6, IL-8, IL-10, and IL-1β as markers of lung inflammation by PCR in a total of n=120 samples from the eight lungs. Intra-biopsy and intra-lung variations were analyzed with equal-variance tests, coefficients of variance, one-way ANOVA, and pairwise mean comparisons. Results Across all donors, the intra-biopsy equal-variance F-values ranged from 0.19-0.95 with means of 0.33, 0.57, 0.62, and 0.58 for IL-1β, IL-6, IL-8, and IL-10. The mean biopsy coefficient of variance was 25.9% across all donors. The mean comparisons of biopsies in each donor showed that the three consistent slices were identical in donors rejected for logistics and thrombotic emboli. Both the lingula and focal injury biopsies demonstrated larger differences in cytokine expression from the rest of the donor lung. Conclusion While intra-biopsy variances were present, they were small and consistent across multiple biopsies in donors, indicating the reliability of repeated analysis of banked specimens. Lungs rejected for non-graft related reasons demonstrated more consistent gene expression. The lingula is not a representative site as it often differed from other biopsies in all donors. We conclude that a donor lung biopsy taken from an area other than the lingula reflects the overall condition of the lung, unless there is obvious localized injury (e.g. infection) which has a unique profile. These findings will reassure the scientific community that a biopsy of the donor lung is indeed representative of the whole lung, and will help to guide diagnostic and therapeutic interventions in donor lungs for transplantation.

Evaluation of the Effects of Propolis and Xylitol Chewable Tablets on the Salivary Concentrations of Oral Micro-organisms in Orthodontic Patients: A Pilot Study

Objectives: This study sought to evaluate the effectiveness of red propolis and xylitol chewable tablets in reducing concentrations of micro-organisms such as Streptococcus mutans (SM) and gram-negative bacteria (GNB). Methods: A total of 12 volunteers of both sexes presenting no caries (ICDAS II 0), users of fixed orthodontic appliances and with visible plaque index were randomly assigned to one of two groups. Was to determine the variations in the concentrations of SM and GNB in the saliva before and after the administration of the chewable tablets. The appearance of adverse reactions and side effects was analyzed. The Mann-Whitney (parametric) test was used for pairwise comparisons of means. The Wilxocon test was also used. Results: The study revealed that the propolis and xylitol chewable tablets had antimicrobial activity, reducing the concentration of GNB by -1.39 log10 CFU/mL (p = 0.036) and compared to placebo (p = 0.004698). There was a significant reduction of SM of -0.22 log10 CFU/mL (p = 0.031) and compared to placebo (p = 0.002165). Conclusion: Thus, in addition to the good safety profile, with a low rate of adverse effects, red propolis and xylitol tablets proved to be an effective potential low-cost alternative to combat dental caries and other periodontal diseases. Key words: Propolis, Xylitol, Chewable tablets, Streptococcus mutans, Dental decay.

Absolute reliability and validity of the OptoGaitTM system to measure spatiotemporal gait parameters during running

The biomechanics of walking and running, in both ground and treadmill conditions, have been extensively analysed and important differences have been reported. Despite some previous studies having examined the validity and reliability of the OptoGait™ system for measuring gait characteristics during walking, no previous works have determined the reliability and validity of this system while running on a treadmill. Therefore, this study aimed to determine the absolute reliability (within-subject variation) and evaluate the concurrent validity of the OptoGait™ system for measuring spatiotemporal variables while running at a comfortable speed by comparing data with a highly accurate system of measuring those parameters (i.e. video analysis at 1000 Hz). Forty-nine endurance runners performed a running protocol on a treadmill at a comfortable speed. Two systems were used to collect data: OptoGait™ system and high-speed video analysis at 1000 Hz. The coefficient of variation (CV) was calculated as a measure of absolute reliability. The OptoGait™ system reported a CV range between 2.2% and 11.4% for spatiotemporal parameters, while the video analysis showed a CV range between 0.02% and 9.9%. To determine concurrent validity, intra class correlation coefficients (ICC) and pairwise comparisons of means (t-test) were calculated between data from both systems. Although the paired t-test demonstrated significant differences between systems, a high level of agreement (ICC &gt; 0.89) was obtained in spatiotemporal parameters between systems. When compared to a high-speed video analysis at 1000 Hz, the results indicate that the OptoGait™ system is a reliable and valid tool to measure spatiotemporal gait characteristics while running on a treadmill at a comfortable speed.

MULTIPLE COMPARISONS IN BIOMEDICAL RESEARCH: THE PROBLEM AND ITS SOLUTIONS

One of the most common but rarely discussed problems in Russian biomedical research is a problem of multiple comparisons. When a researcher performs pairwise comparisons of means in several groups the number of tested ststistical hypotheses increases leading to inflation of the alpha-error. In international scientific literature this issue is well-described and several solutions are offered. The aim of this article is to describe the problem of alpha error inflation and present methods for solving the problem of multiple comparisons. The methods suggested in this paper can be applied at the stages of research planning, data analysis and interpretation of the results. Bonferroni, Sidak, Holm-Bonferroni, Holm-Sidak and the Benjamin-Hochberg methods are described in details. We also present user-friendly examples for manual calculations as well as a description of implementation of the suggested solutions using SPSS software.

Revisiting application of statistics in Agricultural Research in sub-Saharan Africa: Entry points for improvement

The importance of statistics in empowering the agricultural research process and sharpening interventions cannot be over-emphasized. Undocumented evidence points to misconceptions, misuse or underuse of statistics among agricultural researchers in sub-Saharan Africa (SSA); pointing to the possibility that the subject has been part of the causes the unfulfilled targets in the agricultural sector in the region. The objective of this study was to analyse and document weaknesses in statistical practice in agricultural research, with a view to identifying entry points for strengthening the performance of the sector for SSA to be able to achieve its set goals. A desk study involving 165 research articles published in the African Crop Science Journal over the period of 17 years (2000 to 2017) was conducted through a rigorous SWOT analysis for issues related to the use of statistics in the implementation of agricultural research in SSA. A checklist consisting of key elements related to study design; data collection, analysis and exploitation; and presentation, was used to guide the interrogation. Findings indicated that researchers generally made explicit description of treatment structures that fairly matched the study objectives and hypotheses (in the few cases where they were stated), with a few weaknesses in the description of factorial treatment structure. The Randomised Complete Block Design was most commonly used among the designs, with 3-4 replicates. However, there was hardly any justification for its use, as the blocking factors were never mentioned and thus their role in determining the precision of the results was difficult to determine. Analysis of Variance was the main method for data analysis, followed by correlations. The F-test and the associated P-values were the basis for decisions on treatment differences. Most researchers had problems with presentation and interpretation of P-values and significance level. Post adhoc tests mostly used the Least Significant Difference (LSD) for pairwise mean comparisons, with little consideration for the treatment structure, the number of treatments and the nature (qualitative or quantitative). Generally, estimates of treatment means were presented together with various measures of precision, in both tables and graphical forms. In several cases, LSD was used or misused interchangeably with standard error (SE) or standard error of difference (SED). Several statistical software were used for data analysis and presentation, with the main ones being SAS, Genstat and MSTAT-C. Key entry points for improvement heavily lie in human and infrastructural resource capacity improvement, most specifically in (i) periodic review of university and other tertiary institutions’ curricula to provide sufficient time allocation, physical space and relevant infrastructure for true hands on practice; (ii) more effective utilisation of the few statisticians available in the region, (iii) short term staff in-service retooling courses, (iv) sustained statistical service units wherever necessary, and (v) provision for periodic interactive statistician-researcher platforms (such as conferences and workshops) for sharing notes on challenges and achievements during implementation of their research programmes. Key words: Experimental design, P-values, SWOT analysis

Patterns of Floodplain Spatial Heterogeneity in the Southern Rockies, USA

AbstractFloodplain spatial heterogeneity describes the three‐dimensional patchiness of floodplain substrate, surface elevation, and land cover. This heterogeneity results primarily from lateral channel migration and avulsion and decreases under diverse forms of management. Heterogeneity influences floodplain storage time, resilience to disturbance, and biodiversity. We use a data set of 37 floodplain segments covering a range of drainage areas and channel geometries from sites in the Southern Rocky Mountains to examine correlations between floodplain spatial heterogeneity and lateral valley confinement, drainage area, channel planform, and river management. We hypothesized that heterogeneity correlates most strongly with channel planform but found that the best explanatory statistical model included drainage area, planform, and gradient. Pairwise comparisons of means indicate that straight channels have the least heterogeneous floodplains and meandering channels have the greatest, while braided and anastomosing channels have intermediate values. Pairwise comparison of managed and unmanaged river corridors indicates that these populations are significantly different.

Study of common carotid and brachial artery hemodynamic variations in periodontal disease in Central India-a clinical study

Background and aimThe linkage between periodontal and systemic diseases although well researched in the scientific area is not universally cognizant among the clinicians. It is critical to bring about the awareness of this inter-relationship as oral health is suggestive of systemic health. The aim of this study was a thorough hemodynamic assessment in patients having periodontal disease. Settings and designThis is an observational cross sectional study. The patients were selected from Outpatient Department of Cardiology and Periodontology in a tertiary care hospital in urban setting in Nagpur, India. MethodsThe study was conducted on 45 patients aged between 35 and 65 years. Echo-Doppler examination for internal diameter (ID), intima-media thickness (IMT) and blood flow velocity (PSV) measurements was executed in the right and left common carotid artery (CCA) and brachial artery (BA). Periodontal disease status was determined using parameters like Gingival Index, Plaque Index, probing pocket depth (PPD) and clinical attachment level (CAL). Statistical analysisDue to multiple comparison groups one-way Analysis of variance (ANOVA) with Bonferroni multiple comparison tests have been performed to conduct all possible pair-wise comparisons of means. ResultsThe present study showed that Carotid IMT and ID were high in the patients having cardiovascular disease (CVD) and periodontitis as compared to CVD alone, showing the additional effect caused by the presence of periodontal disease. ConclusionThe study findings support the proposition that periodontal disease may be associated with endothelial dysfunction which leads to atherosclerosis or hardening of arteries indicating increased cardiovascular risk.

Impact of Load Variation on the Accuracy of Gait Recognition from Surface EMG Signals

As lower-limb exoskeleton and prostheses are developed to become smarter and to deploy man–machine collaboration, accurate gait recognition is crucial, as it contributes to the realization of real-time control. Many researchers choose surface electromyogram (sEMG) signals to recognize the gait and control the lower-limb exoskeleton (or prostheses). However, several factors still affect its applicability, of which variation in the loads is an essential one. This study aims to (1) investigate the effect of load variation on gait recognition; and to (2) discuss whether a lower-limb exoskeleton control system trained by sEMG from different loads works well in multi-load applications. In our experiment, 10 male college students were selected to walk on a treadmill at three different speeds (V3 = 3 km/h, V5 = 5 km/h, and V7 = 7 km/h) with four different loads (L0 = 0, L20 = 20%, L30 = 30%, L40 = 40% of body weight, respectively), and 50 gait cycles were performed. Back propagation neural networks (BPNNs) were used for gait recognition, and a support vector machine (SVM) and k-nearest neighbor (k-NN) were used for comparison. The result showed that (1) load variation has significant effects on the accuracy of gait recognition (p &lt; 0.05) under the three speeds when the loads range in L0, L20, L30, or L40, but no significant impact is found when the loads range in L0, L20, or L30. The least significant difference (LSD) post hoc, which can explore all possible pair-wise comparisons of means that comprise a factor using the equivalent of multiple t-tests, reveals that there is a significant difference between the L40 load and the other three loads (L0, L20, L30), but no significant difference was found among the L0, L20, and L30 loads. The total mean accuracy of gait recognition of the intra-loads and inter-loads was 91.81%, and 69.42%, respectively. (2) When the training data was taken from more types of loads, a higher accuracy in gait recognition was obtained at each speed, and the statistical analysis shows that there was a substantial influence for the kinds of loads in the training set on the gait recognition accuracy (p &lt; 0.001). It can be concluded that an exoskeleton (or prosthesis) control system that is trained in a single load or the parts of loads is insufficient in the face of multi-load applications.

Invasion of a Legume Ecosystem Engineer in a Cold Biome Alters Plant Biodiversity

Plant ecosystem engineers are widely used to combat land degradation. However, the ability of those plants to modulate limiting abiotic and biotic resources of other species can cause damage to ecosystems in which they become invasive. Here, we use Lupinus nootkatensis as example to estimate and project the hazardous potential of nitrogen fixing herbaceous plants in a sub-polar oceanic climate. L. nootkatensis was introduced to Iceland in the 1940s to address erosion problems and foster reforestation, but subsequently became a high-latitude invader. In a local field survey, we quantified the impact of L. nootkatensis invasion at three different cover levels (0, 10–50, and 51–100%) upon native plant diversity, richness, and community composition of heath-, wood-, and grasslands using a pairwise comparison design and comparisons of means. Afterward, we scaled impacts up to the ecosystem and landscape level by relating occurrences of L. nootkatensis to environmental and human-mediated variables across Iceland using a species distribution model. Plant diversity was significantly deteriorated under high lupine cover levels of the heath- and woodland, but not in the grassland. Plant species richness of the most diverse habitat, the heathland, linearly decreased with lupine cover level. The abundance of small rosettes, cushion plants, orchids, and small woody long-lived plants of the heath declined with invader presence, while the abundance of late successional species and widespread nitrophilous ruderals in wood- and grasslands increased. Distribution modeling revealed 13.3% of Iceland’s land surface area to be suitable lupine habitat. Until 2061–2080, this area will more than double and expand significantly into the Central Highlands due to human mediation and increasingly favorable climatic conditions. Species-rich habitats showed a loss of plant species diversity and richness as well as a change in community composition even in low lupine cover classes. The future increase of suitable lupine habitat might lead to the displacement of cold-adapted native plant species and will certainly challenge conservation as well as restoration of ecosystems in the cold climate of Iceland, but also elsewhere. Lupine invasion speeds up succession, which may be additive with climate change effects, and accelerates ecological change in cold biomes.