Testing Mean Differences among Groups: Multivariate and Repeated Measures Analysis with Minimal Assumptions

Ammonium nutrition modifies cellular calcium distribution influencing ammonium-induced growth inhibition

Proper plant growth requires balanced nutrient levels. In this study, we analyzed the relationship between ammonium (NH4+) nutrition and calcium (Ca2+) homeostasis in the leaf tissues of wild-type and mutant Arabidopsis specimens provided with different nitrogen sources (NH4+ and nitrate, NO3-). Providing plants with NH4+ as the sole nitrogen source disrupts Ca2+ homeostasis, which is essential for activating signaling pathways and maintaining the cell wall structure. The results revealed that the lower Ca2+ content in Arabidopsis leaves under NH4+ stress might result from reduced transpiration pull, which could impair root-to-shoot Ca2+ transport. Moreover, NH4+ nutrition increased the expression of genes encoding proteins responsible for exporting Ca2+ from the cytosol of leaf cells. Furthermore, overexpression of the Ca2+/H+ antiporter 1 (CAX1) gene alleviates the effects of NH4+ syndrome, including stunted growth. The oeCAX1 plants, characterized by a lower apoplastic Ca2+ level, grew better under NH4+ stress than wild-type plants. Evaluation of the mechanical properties of the leaf blades, including stiffness, strength, toughness, and extensibility, showed that the wild-type and oeCAX1 plants responded differently to the nitrogen source, highlighting the role of cell wall metabolism in inhibiting the growth of NH4+-stressed plants.

Bootstrap tests for simultaneous monotone ordering of effects in a two-way ANOVA

In a two-way additive analysis of variance (ANOVA) model, we consider the problem of testing for homogeneity of both row and column effects against their simultaneous ordering. The error variances are assumed to be heterogeneous with unbalanced samples in each cell. Two simultaneous test procedures are developed-the first one using the likelihood ratio test (LRT) statistics of two independent hypotheses and another based on the consecutive pairwise differences of estimators of effects. The parametric bootstrap (PB) approach is used to find critical points of both the tests and the asymptotic accuracy of the bootstrap is established. An extensive simulation study shows that the proposed tests achieve the nominal size and have very good power performance. The robustness of the tests is also analyzed under deviation from normality. An "R" package is developed and shared on "GitHub" for ease of implementation of users. The proposed tests are illustrated using a real data set on the mortality due to alcoholic liver disease and it is shown that age and gender have a significant impact on the increasing incidence of mortality.

Evidence from personal ornaments suggest nine distinct cultural groups between 34,000 and 24,000 years ago in Europe

Mechanisms governing the relationship between genetic and cultural evolution are the subject of debate, data analysis and modelling efforts. Here we present a new georeferenced dataset of personal ornaments worn by European hunter-gatherers during the so-called Gravettian technocomplex (34,000-24,000 years ago), analyse it with multivariate and geospatial statistics, model the impact of distance on cultural diversity and contrast the outcome of our analyses with up-to-date palaeogenetic data. We demonstrate that Gravettian ornament variability cannot be explained solely by isolation-by-distance. Analysis of Gravettian ornaments identified nine geographically discrete cultural entities across Europe. While broadly in agreement with palaeogenetic data, our results highlight a more complex pattern, with cultural entities located in areas not yet sampled by palaeogenetics and distinctive entities in regions inhabited by populations of similar genetic ancestry. Integrating personal ornament and biological data from other Palaeolithic cultures will elucidate the complex narrative of population dynamics of Upper Palaeolithic Europe.

Univariate and multivariate sex differences and similarities in gray matter volume within essential language-processing areas

BACKGROUND

Sex differences in language-related abilities have been reported. It is generally assumed that these differences stem from a different organization of language in the brains of females and males. However, research in this area has been relatively scarce, methodologically heterogeneous and has yielded conflicting results.

METHODS

Univariate and multivariate sex differences and similarities in gray matter volume (GMVOL) within 18 essential language-processing brain areas were assessed in a sex-balanced sample (N = 588) of right-handed young adults. Univariate analyses involved location, spread, and shape comparisons of the females' and males' distributions and were conducted with several robust statistical methods able to quantify the size of sex differences and similarities in a complementary way. Multivariate sex differences and similarities were estimated by the same methods in the continuous scores provided by two distinct multivariate procedures (logistic regression and a multivariate analog of the Wilcoxon-Mann-Whitney test). Additional analyses were addressed to compare the outcomes of these two multivariate analytical strategies and described their structure (that is, the relative contribution of each brain area to the multivariate effects).

RESULTS

When not adjusted for total intracranial volume (TIV) variation, "large" univariate sex differences (males > females) were found in all 18 brain areas considered. In contrast, "small" differences (females > males) in just two of these brain areas were found when controlling for TIV. The two multivariate methods tested provided very similar results. Multivariate sex differences surpassed univariate differences, yielding "large" differences indicative of larger volumes in males when calculated from raw GMVOL estimates. Conversely, when calculated from TIV-adjusted GMVOL, multivariate differences were "medium" and indicative of larger volumes in females. Despite their distinct size and direction, multivariate sex differences in raw and TIV-adjusted GMVOL shared a similar structure and allowed us to identify the components of the SENT_CORE network which more likely contribute to the observed effects.

CONCLUSIONS

Our results confirm and extend previous findings about univariate sex differences in language-processing areas, offering unprecedented evidence at the multivariate level. We also observed that the size and direction of these differences vary quite substantially depending on whether they are estimated from raw or TIV-adjusted GMVOL measurements.

Emotional Bias among Individuals at Risk for Seasonal Affective Disorder-An EEG Study during Remission in Summer

Emotional bias in attention and memory is well researched in depression. Patients with depression prioritize processing of negative information over positive input. While there is evidence that emotional bias exists in seasonal affective disorder (SAD) during winter, it is unclear whether such altered cognition exists also during summer. Moreover, it is unclear whether such bias affects attention, memory, or both. In this study, we investigated 110 individuals in summer, 34 of whom reported suffering from low mood during winter, according to the seasonal pattern assessment questionnaire. While the electroencephalogram was recorded, participants learned 60 emotional pictures and subsequently were asked to recognize them in an old/new task. There were no clear group differences in behavioral measures, and no brain response differences in frontal alpha power during learning. During recognition, at 100-300 ms post stimulus individuals with higher seasonality scores exhibited larger alpha power in response to negative as compared to neutral stimuli, while individuals with low seasonality scores exhibited larger alpha power in response to positive as compared to neutral stimuli. While we cannot draw conclusions whether this is an effect of attention or memory, the finding suggests that early cognitive processes are altered already during summer in individuals with increased likelihood to experience SAD during winter. Our data provide evidence for an all-year-round cognitive vulnerability in this population.

Shorter duration of slow wave sleep is related to symptoms of depression in patients with epilepsy

Slow wave sleep duration and spectral abnormalities are related to both epilepsy and depression, but it is unclear how depressive symptoms in patients with epilepsy are affected by slow wave sleep duration and clinical factors, and how the spectral characteristics of slow wave sleep reflect a potential interaction of epilepsy and depression. Long-term video-EEG monitoring was conducted in 51 patients with focal epilepsy, 13 patients with generalized epilepsy, and 9 patients without epilepsy. Slow wave sleep segments were manually marked in the EEG and duration as well as EEG power spectra were extracted. Depressive symptoms were documented with the Beck Depression Inventory (BDI). At least mild depressive symptoms (BDI > 9) were found among 23 patients with focal epilepsy, 5 patients with generalised epilepsy, and 6 patients who had no epilepsy diagnosis. Slow wave sleep duration was shorter for patients with at least mild depressive symptoms (p =.004), independently from epilepsy diagnosis, antiseizure medication, age, and sex. Psychoactive medication was associated with longer slow wave sleep duration (p =.008). Frontal sigma band power (13-15 Hz) during slow wave sleep was higher for patients without epilepsy and without depressive symptoms as compared to patients without depressive symptoms but with focal epilepsy (p =.005). Depressive symptoms affect slow wave sleep duration of patients with epilepsy similarly as in patients without epilepsy. Since reduced slow wave sleep can increase the likelihood of seizure occurrence, these results stress the importance of adequate treatment for patients with epilepsy who experience depressive symptoms.

Obesity Status and Physical Fitness Levels in Male and Female Portuguese Adolescents: A Two-Way Multivariate Analysis

Obesity and decreasing fitness levels among the youth are growing concerns in Portugal, similar to other developed countries, with implications for health and psychomotor development. Understanding the influence of health determinants such as sex and age are crucial for developing effective public health strategies. This study aimed to analyze the association between sex and chronological age with obesity status and physical fitness in Portuguese adolescents. A total of 170 adolescents (85 males and 85 females) were evaluated for body mass index, abdominal adiposity, aerobic fitness, abdominal resistance, upper limb resistance, lower limb power, and maximal running speed in a 40 m sprint using the FITescola^® physical fitness battery, a Portuguese government initiative. The general model, analyzed using Pillai's trace, showed a significant effect of age and sex on body mass index, abdominal circumference, aerobic fitness, abdominal resistance, upper limb resistance, lower limb power, and maximal running speed (V = 0.99, F (7) = 10,916.4, p < 0.001, partial η2, sex = 0.22; age = 0.43, sex and age interaction = 0.10). Boys had higher physical fitness levels than girls in most tests, but both sex groups had a significantly higher proportion of non-fit adolescents, with boys showing the highest number of participants classified as non-fit.

¿Modula el efecto del feedback la percepción de competencia del entrenador?

El objetivo fue analizar el efecto de diferentes tipos de feedback sobre variables psicológicas y de rendimiento en función de la percepción del deportista de la competencia del entrenador. Se realizó un estudio de caso con 33 futbolistas asignados aleatoriamente a tres condiciones experimentales (feedback positivo, negativo y ausencia de feedback). Se midieron velocidad y precisión de lanzamientos a portería, valoración de competencia, competencia percibida, motivación autónoma y vitalidad subjetiva. Se empleó un nivel ? de 0,05 para los análisis. El grupo feedback positivo exhibió niveles más altos de valoración de competencia, competencia percibida, motivación autónoma y bienestar, que los de feedback negativo y ausencia de feedback, en sujetos con alta percepción de competencia del entrenador. Este efecto no se observó en aquellos con baja percepción de competencia del entrenador. La percepción del jugador sobre la competencia del entrenador podría ser un factor en la modulación de las diferencias generadas en cuanto al tipo de feedback.

Older Adults' Vigorous Occupational Physical Activity Levels in Six Countries Are Explained by Country and 'Having Multiple Jobs'

Several studies have compared physical activity (PA) levels between countries, but none of these studies focused on older adults and occupational PA. This study aimed to assess potential inequalities in older adults' occupational PA across six countries and to ascertain whether having multiple jobs is a factor that interacts with country of residence to modify inequalities. This study adopted a cross-sectional design with a statistical technique screening for potential covariates. Older adults (mean age = 64 years; range = 50-114 years) from six countries (Russia, Mexico, China, India, Ghana, and South Africa) participated in the study. We utilised data from the first wave of the Study on Global AGEing and Adult Health (SAGE). These data were collected from 2007 to 2010. A random sample of 34,114 older adults completed the survey. We analysed the data with a two-way multivariate analysis of variance after screening for the ultimate covariates. There were differences in occupational PA levels (i.e., vigorous and moderate PA) among the six countries. Occupational PA levels were not significantly associated with having multiple jobs. However, having multiple jobs interacted with country of residence to influence vigorous occupational PA. Older adults from most countries who had more than one job reported more vigorous occupational PA. Older adults' occupational PA differed among the six countries, and having multiple jobs was associated with more vigorous occupational PA. Older adults who keep multiple jobs at a time may be more active than their counterparts who had one job or were unemployed.

Interactions between the Entomopathogenic Fungus Metarhizium anisopliae ICIPE 20 and the Endoparasitoid Dolichogenidea gelechiidivoris, and Implications for Combined Biocontrol of Tuta absoluta

The Integrated Pest Management (IPM) approach have been widely promoted and used for the management of native and invasive pests, while the use of various components of the IPM can have a synergetic, additive, or antagonistic effect on each other; this study evaluated the susceptibility of Dolichogenidea gelechiidivoris (Marsh) (Hymenoptera: Braconidae), to the Metarhizium anisopliae (Metschnikoff) ICIPE 20 through direct and indirect infection approaches. The effect of fungus on parasitoid longevity, survival of parasitized-larvae, preference of the parasitoid to fungal treated and untreated larvae, and percent parasitism of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) under different infection scenarios were assessed. The direct application of dry conidia to the parasitoid prior to exposure to the host, reduced D. gelechiidivoris longevity, though the infected female wasps still yielded high parasitism (over 70%). Infecting the parasitized larvae at different ages led to a respective reduction of parasitoid emergence by 35% and 23% for infection at 1 and 5 days post-parasitisation. Exposure of healthy-D. gelechiidivoris adults to a plant-sprayed with fungus did not affect their longevity, and no discriminatory host selection was observed. The highest mortality (~80%) of T. absoluta was achieved when D. gelechiidivoris and M. anisopliae ICIPE 20 were used in combination, indicating an additive impact on the target pest; however, field validation can shed more light on this outcome.

Are High Frequency Oscillations in Scalp EEG Related to Age?

BACKGROUND

High-frequency oscillations (HFOs) have received much attention in recent years, particularly in the clinical context. In addition to their application as a marker for pathological changes in patients with epilepsy, HFOs have also been brought into context with several physiological mechanisms. Furthermore, recent studies reported a relation between an increase of HFO rate and age in invasive EEG recordings. The present study aimed to investigate whether this relation can be replicated in scalp-EEG.

METHODS

We recorded high-density EEG from 11 epilepsy patients at rest as well as during motor performance. Manual detection of HFOs was performed by two independent raters following a standardized protocol. Patients were grouped by age into younger (<25 years) and older (>50 years) participants.

RESULTS

No significant difference of HFO-rates was found between groups [U = 10.5, p = 0.429, r = 0.3].

CONCLUSIONS

Lack of replicability of the age effect of HFOs may be due to the local propagation patterns of age-related HFOs occurring in deep structures. However, limitations such as small sample size, decreased signal-to-noise ratio as compared to invasive recordings, as well as HFO-mimicking artifacts must be considered.

EEG-responses to mood induction interact with seasonality and age

The EEG is suggested as a potential diagnostic and prognostic biomarker for seasonal affective disorder (SAD). As a pre-clinical form of SAD, seasonality is operationalized as seasonal variation in mood, appetite, weight, sleep, energy, and socializing. Importantly, both EEG biomarkers and seasonality interact with age. Inducing sad mood to assess cognitive vulnerability was suggested to improve the predictive value of summer assessments for winter depression. However, no EEG studies have been conducted on induced sad mood in relation to seasonality, and no studies so far have controlled for age. We recorded EEG and calculated bandpower in 114 participants during rest and during induced sad mood in summer. Participants were grouped by age and based on a seasonality score as obtained with the seasonal pattern assessment questionnaire (SPAQ). Participants with high seasonality scores showed significantly larger changes in EEG power from rest to sad mood induction, specifically in the alpha frequency range (p = 0.027), compared to participants with low seasonality scores. Furthermore, seasonality interacted significantly with age (p < 0.001), with lower activity in individuals with high seasonality scores that were older than 50 years but the opposite pattern in individuals up to 50 years. Effects of sad mood induction on brain activity are related to seasonality and can therefore be consider as potential predicting biomarkers for SAD. Future studies should control for age as a confounding factor, and more studies are needed to elaborate on the characteristics of EEG biomarkers in participants above 50 years.

Early factors related to mortality in children treated with bi-level noninvasive ventilation and CPAP

OBJECTIVE

To describe and analyze the characteristics and the early risk factors for mortality of noninvasive ventilation (NIV) in critically ill children.

STUDY DESIGN

A multicenter, prospective, observational 2-year study carried out with critically ill patients (1 month - 18 years of age) who needed NIV. Clinical data and NIV parameters during the first 12 h of admission were collected. A multilevel mixed-effects logistic regression was performed to identify mortality risk factors.

RESULTS

A total of 781 patients (44.2 ± 57.7 months) were studied (57.8% male). Of them, 53.7% had an underlying condition, and 47.1% needed NIV for lower airway respiratory pathologies. Bi-level NIV was the initial support in 78.2% of the patients. Continuous positive airway pressure (CPAP) was used more in younger patients (33.7%) than in older ones (9.7%; p < .001). About 16.7% had to be intubated and 6.2% died. The risk factors for mortality were immunodeficiency (odds ratio [OR] = 11.79; 95% confidence interval [CI] = 2.95-47.13); cerebral palsy (OR = 5.86; 95% CI = 1.94-17.65); presence of apneas on admission (OR = 5.57; 95% CI = 2.13-14.58); tachypnea 6 h after NIV onset (OR = 2.59; 95% CI = 1.30-6.94); and NIV failure (OR = 6.54; 95% CI = 2.79-15.34).

CONCLUSION

NIV is used with great variability in types of support. Younger children receive CPAP more frequently than older children. Immunodeficiency, cerebral palsy, apneas on admission, tachypnea 6 h after NIV onset, and NIV failure are the early factors associated with mortality.

Generalised M-quantile random-effects model for discrete response: An application to the number of visits to physicians

In this paper, we extend the linear M-quantile random intercept model (MQRE) to discrete data and use the proposed model to evaluate the effect of selected covariates on two count responses: the number of generic medical examinations and the number of specialised examinations for health districts in three regions of central Italy. The new approach represents an outlier-robust alternative to the generalised linear mixed model with Gaussian random effects and it allows estimating the effect of the covariates at various quantiles of the conditional distribution of the target variable. Results from a simulation experiment, as well as from real data, confirm that the method proposed here presents good robustness properties and can be in certain cases more efficient than other approaches.

Nest construction and presence do not alter territorial aggression in male threespine stickleback

Constructing a nest within a mating territory provides a clear benefit to the resident, particularly by improving the opportunity to mate. It is unclear whether animals who use nests exclusively for reproductive purposes account for either the effort invested or the resulting increase in mating potential when valuing their territories. We sought to explicitly reveal a nest’s added subjective resource value through within-group comparison of aggressive behaviour before and after nest construction. An increase in aggression following construction would indicate that the resident perceives greater subjective value in his territory, and thus values the nest. Threespine stickleback, Gasterosteus aculeatus, fish demonstrate stereotypical aggressive behaviours during an easily induced territorial defence. The male’s nest is used exclusively for reproductive purposes, avoiding any confound of shelter. Contrary to our hypothesis, neither nest presence, timing of construction, nor nesting outcome was associated with differences in behavioural measures of territorial aggression. Assessed behaviours were robust, repeatable and inter-correlated. We conclude that territorial aggression is neither predictive of nor altered by nesting in threespine stickleback fish. Our results suggest that nests used transiently for a portion of the mating season add negligible subjective resource value to a territory. We additionally demonstrate that examinations of territorial aggression in sticklebacks do not need to control for nest building, improving statistical power by decreasing dropout rates. These results dovetail with recent work in other fish species to suggest that assessment of territorial aggression absent a nest may be practicable for fish in general.

Perceptual metacognition of human faces is causally supported by function of the lateral prefrontal cortex

Metacognitive awareness—the ability to know that one is having a particular experience—is thought to guide optimal behavior, but its neural bases continue to be the subject of vigorous debate. Prior work has identified correlations between perceptual metacognitive ability and the structure and function of lateral prefrontal cortex (LPFC); however, evidence for a causal role of this region in promoting metacognition is controversial. Moreover, whether LPFC function promotes metacognitive awareness of perceptual and emotional features of complex, yet ubiquitous face stimuli is unknown. Here, using model-based analyses following a causal intervention to LPFC in humans, we demonstrate that LPFC function promotes metacognitive awareness of the orientation of faces—although not of their emotional expressions. Collectively, these data support the causal involvement of the prefrontal cortex in metacognitive awareness, and indicate that the role of LPFC in metacognition encompasses perceptual experiences of naturalistic social stimuli.

Regina C. Lapate et al. study the role of lateral prefrontal cortex (LPFC) in metacognitive awareness in humans. They use transcranial magnetic stimulation, emotional face stimuli and model-based analyses to demonstrate that LPFC function promotes metacognitive awareness of the orientation, but not the emotional expression, of human faces.

Prediction of Cognitive Decline in Temporal Lobe Epilepsy and Mild Cognitive Impairment by EEG, MRI, and Neuropsychology

Cognitive decline is a severe concern of patients with mild cognitive impairment. Also, in patients with temporal lobe epilepsy, memory problems are a frequently encountered problem with potential progression. On the background of a unifying hypothesis for cognitive decline, we merged knowledge from dementia and epilepsy research in order to identify biomarkers with a high predictive value for cognitive decline across and beyond these groups that can be fed into intelligent systems. We prospectively assessed patients with temporal lobe epilepsy (N = 9), mild cognitive impairment (N = 19), and subjective cognitive complaints (N = 4) and healthy controls (N = 18). All had structural cerebral MRI, EEG at rest and during declarative verbal memory performance, and a neuropsychological assessment which was repeated after 18 months. Cognitive decline was defined as significant change on neuropsychological subscales. We extracted volumetric and shape features from MRI and brain network measures from EEG and fed these features alongside a baseline testing in neuropsychology into a machine learning framework with feature subset selection and 5-fold cross validation. Out of 50 patients, 27 had a decline over time in executive functions, 23 in visual-verbal memory, 23 in divided attention, and 7 patients had an increase in depression scores. The best sensitivity/specificity for decline was 72%/82% for executive functions based on a feature combination from MRI volumetry and EEG partial coherence during recall of memories; 95%/74% for visual-verbal memory by combination of MRI-wavelet features and neuropsychology; 84%/76% for divided attention by combination of MRI-wavelet features and neuropsychology; and 81%/90% for increase of depression by combination of EEG partial directed coherence factor at rest and neuropsychology. Combining information from EEG, MRI, and neuropsychology in order to predict neuropsychological changes in a heterogeneous population could create a more general model of cognitive performance decline.

A simulation study to compare robust tests for linear mixed-effects meta-regression

The explanation of heterogeneity when synthesizing different studies is an important issue in meta-analysis. Besides including a heterogeneity parameter in the statistical model, it is also important to understand possible causes of between-study heterogeneity. One possibility is to incorporate study-specific covariates in the model that account for between-study variability. This leads to linear mixed-effects meta-regression models. A number of alternative methods have been proposed to estimate the (co)variance of the estimated regression coefficients in these models, which subsequently drives differences in the results of statistical methods. To quantify this, we compare the performance of hypothesis tests for moderator effects based upon different heteroscedasticity consistent covariance matrix estimators and the (untruncated) Knapp-Hartung method in an extensive simulation study. In particular, we investigate type 1 error and power under varying conditions regarding the underlying distributions, heterogeneity, effect sizes, number of independent studies, and their sample sizes. Based upon these results, we give recommendations for suitable inference choices in different scenarios and highlight the danger of using tests regarding the study-specific moderators based on inappropriate covariance estimators.

Effects of Antiepileptic Drug Tapering on Episodic Memory as Measured by Virtual Reality Tests

Antiepileptic drugs impair episodic memory in patients with epilepsy, but this effect has so far only been examined with tests that do not provide first-person experience-an aspect that is crucial for episodic memory. Virtual reality techniques facilitate the development of ecologically valid tests. In the present study, we measure the effect of antiepileptic drug changes in a within-subject design using a virtual reality test in order to provide direct evidence for effects of antiepileptic drugs on episodic memory. Among 106 recruited patients, 97 participated in a virtual reality test up to six times during a 4-day hospitalization, and 78 patients underwent changes in drug load during this period. There were six parallel versions of a virtual town test, with immediate recall and delayed recall after about 12 h. The test requires recall of elements, details, sequence of experience, and egocentric and allocentric spatial memory. We determined drug load by defined daily dose, and compared test performance at lowest antiepileptic drug load to highest antiepileptic drug load. Across the six towns, performance was lower in delayed compared to immediate recall. There was an overall effect of medication when comparing patients taking vs. not taking antiepileptic drugs and/or psychoactive drugs (p = 0.005). Furthermore, there was a within-subject effect of antiepileptic drug load (p = 0.01), indicating lower test performance at higher drug load. There was no effect of gender, daytime, circadian type, depression, seizures, lesions, and epilepsy. For patients with temporal lobe epilepsy, there was no effect of lateralization. The present study provides direct evidence for episodic memory impairment due to antiepileptic drugs, suggesting that a small change in drug load can matter. This study can serve as a proof of principle for the methodology, but a larger sample is needed to examine the differential effects of individual antiepileptic drugs.