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Qin, L. "Functional mixed-effects model for periodic data." Biostatistics 7, no. 2 (August 3, 2005): 225–34. http://dx.doi.org/10.1093/biostatistics/kxj003.
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Maiti, Tapabrata, Samiran Sinha, and Ping-Shou Zhong. "Functional Mixed Effects Model for Small Area Estimation." Scandinavian Journal of Statistics 43, no. 3 (March 15, 2016): 886–903. http://dx.doi.org/10.1111/sjos.12218.
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Chen, Huaihou, and Yuanjia Wang. "A Penalized Spline Approach to Functional Mixed Effects Model Analysis." Biometrics 67, no. 3 (December 14, 2010): 861–70. http://dx.doi.org/10.1111/j.1541-0420.2010.01524.x.
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Kang, Hakmook, Hernando Ombao, Crystal Linkletter, Nicole Long, and David Badre. "Spatio-Spectral Mixed-Effects Model for Functional Magnetic Resonance Imaging Data." Journal of the American Statistical Association 107, no. 498 (June 2012): 568–77. http://dx.doi.org/10.1080/01621459.2012.664503.
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Chen, Ji, David Ohlssen, and Yingchun Zhou. "Functional Mixed Effects Model for the Analysis of Dose-Titration Studies." Statistics in Biopharmaceutical Research 10, no. 3 (June 22, 2018): 176–84. http://dx.doi.org/10.1080/19466315.2018.1458649.
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Su, Yu-Ru, Chongzhi Di, Stephanie Bien, Licai Huang, Xinyuan Dong, Goncalo Abecasis, Sonja Berndt, et al. "A Mixed-Effects Model for Powerful Association Tests in Integrative Functional Genomics." American Journal of Human Genetics 102, no. 5 (May 2018): 904–19. http://dx.doi.org/10.1016/j.ajhg.2018.03.019.
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Rakêt, Lars Lau, Stefan Sommer, and Bo Markussen. "A nonlinear mixed-effects model for simultaneous smoothing and registration of functional data." Pattern Recognition Letters 38 (March 2014): 1–7. http://dx.doi.org/10.1016/j.patrec.2013.10.018.
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Liu, Zhuqing, Andreas J. Bartsch, Veronica J. Berrocal, and Timothy D. Johnson. "A mixed-effects, spatially varying coefficients model with application to multi-resolution functional magnetic resonance imaging data." Statistical Methods in Medical Research 28, no. 4 (January 15, 2018): 1203–15. http://dx.doi.org/10.1177/0962280217752378.
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Spatial resolution plays an important role in functional magnetic resonance imaging studies as the signal-to-noise ratio increases linearly with voxel volume. In scientific studies, where functional magnetic resonance imaging is widely used, the standard spatial resolution typically used is relatively low which ensures a relatively high signal-to-noise ratio. However, for pre-surgical functional magnetic resonance imaging analysis, where spatial accuracy is paramount, high-resolution functional magnetic resonance imaging may play an important role with its greater spatial resolution. High spatial resolution comes at the cost of a smaller signal-to-noise ratio. This begs the question as to whether we can leverage the higher signal-to-noise ratio of a standard functional magnetic resonance imaging study with the greater spatial accuracy of a high-resolution functional magnetic resonance imaging study in a pre-operative patient. To answer this question, we propose to regress the statistic image from a high resolution scan onto the statistic image obtained from a standard resolution scan using a mixed-effects model with spatially varying coefficients. We evaluate our model via simulation studies and we compare its performance with a recently proposed model that operates at a single spatial resolution. We apply and compare the two models on data from a patient awaiting tumor resection. Both simulation study results and the real data analysis demonstrate that our newly proposed model indeed leverages the larger signal-to-noise ratio of the standard spatial resolution scan while maintaining the advantages of the high spatial resolution scan.
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Levshina, Natalia. "When variables align: A Bayesian multinomial mixed-effects model of English permissive constructions." Cognitive Linguistics 27, no. 2 (May 1, 2016): 235–68. http://dx.doi.org/10.1515/cog-2015-0054.
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AbstractThis paper is a quantitative multifactorial study of the near-synonymous constructionslet+V,allow+toV andpermit+toV based on the British National Corpus. The study investigates the differences between these constructions with the help of 23 formal, semantic, social and collostructional variables. A Bayesian multinomial mixed-effects model reveals a remarkable alignment of the variables that represent different dimensions of variation, namely, the linguistic distance between the predicates, the conceptual distance between the events they represent, the distance between the speaker and the Permitter and Permittee on the animacy/entrenchment/empathy hierarchy, the social and communicative distance between the interlocutors, as well as the strength of collostructional attraction between the constructions and second verb slot fillers. The paper offers several possible explanations for this alignment from a cognitive, functional and historical perspective.
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Silk, Matthew J., Xavier A. Harrison, and David J. Hodgson. "Perils and pitfalls of mixed-effects regression models in biology." PeerJ 8 (August 12, 2020): e9522. http://dx.doi.org/10.7717/peerj.9522.
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Biological systems, at all scales of organisation from nucleic acids to ecosystems, are inherently complex and variable. Biologists therefore use statistical analyses to detect signal among this systemic noise. Statistical models infer trends, find functional relationships and detect differences that exist among groups or are caused by experimental manipulations. They also use statistical relationships to help predict uncertain futures. All branches of the biological sciences now embrace the possibilities of mixed-effects modelling and its flexible toolkit for partitioning noise and signal. The mixed-effects model is not, however, a panacea for poor experimental design, and should be used with caution when inferring or deducing the importance of both fixed and random effects. Here we describe a selection of the perils and pitfalls that are widespread in the biological literature, but can be avoided by careful reflection, modelling and model-checking. We focus on situations where incautious modelling risks exposure to these pitfalls and the drawing of incorrect conclusions. Our stance is that statements of significance, information content or credibility all have their place in biological research, as long as these statements are cautious and well-informed by checks on the validity of assumptions. Our intention is to reveal potential perils and pitfalls in mixed model estimation so that researchers can use these powerful approaches with greater awareness and confidence. Our examples are ecological, but translate easily to all branches of biology.
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Karcher, Helene, Marina Savelieva, Luyuan Qi, Noemi Hummel, Angelika Caputo, Valery Risson, Gorana Capkun, and Alzheimer’s Disease Neuroimaging Initiative. "Modelling Decline in Cognition to Decline in Function in Alzheimer’s Disease." Current Alzheimer Research 17, no. 7 (November 16, 2020): 635–57. http://dx.doi.org/10.2174/1567205017666201008105429.
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Objective: : The study aimed to evaluate and quantify the temporal link between cognitive and functional decline, and assess the impact of the apolipoprotein E4 (APOE-e4) genotype on Alzheimer’s disease (AD) progression. Methods: A nonlinear mixed-effects Emax model was developed using longitudinal data from 659 patients with dementia due to AD sourced from the Alzheimer's disease neuroimaging initiative (ADNI) database. A cognitive decline model was first built using a cognitive subscale of the AD assessment scale (delayed word recall) as the endpoint, followed by a functional decline model, using the functional assessment questionnaire (FAQ) as the endpoint. Individual and population cognitive decline from the first model drove a functional decline in the second model. The impact of the APOE-e4 genotype status on the dynamics of AD progression was evaluated using the model. Results: Mixed-effects Emax models adequately quantified population average and individual disease trajectories. The model captured a higher initial cognitive impairment and final functional impairment in APOE-e4 carriers than non-carriers. The age at cognitive decline and diagnosis of dementia due to AD was significantly lower in APOE-e4 carriers than that of non-carriers. The average [standard deviation] time shift between cognitive and functional decline, i.e. the time span between half of the maximum cognitive decline and half of the maximum functional decline, was estimated as 1.5 [1.6] years. Conclusion: The present analysis quantifies the temporal link between a cognitive and functional decline in AD progression at the population and individual level, and provides information about the potential benefits of pre-clinical AD treatments on both cognition and function.
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Biswas, Sabyasachi, Souvik Chakraborty, Indrajit Ghosh, and Satish Chandra. "Saturation Flow Model for Signalized Intersection under Mixed Traffic Condition." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 15 (June 4, 2018): 55–65. http://dx.doi.org/10.1177/0361198118777407.
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Saturation flow is one of the most important functional parameters at signalized intersections. It is to be noted that saturation flow is a functional measure of the intersection operation, which indicates the probable capacity if working in an ideal situation. However, determination of the saturation flow is a challenging task in developing countries like India where vehicles with diverse static and dynamic characteristics use the same carriageway. At the same time, it is influenced by several other factors. In this context, the present research is carried out to examine the effects of traffic composition, approach width and right-turning movements on saturation flow under heterogeneous traffic conditions. This paper proposes a model for computing saturation flow at the signalized intersection under mixed traffic condition based on Kriging approach. A detailed comparison of the mean saturation flow values obtained by the conventional method, regression method, and Kriging method has also been presented. Low mean absolute percentage error values (<5%) have been obtained for saturation flow by Kriging method with respect to the conventional method. Finally, the proposed models are used to evaluate the impact of right-turning vehicles on saturation flow under shared lane condition.
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Boisgontier, Matthieu P., Dan Orsholits, Martina von Arx, Stefan Sieber, Matthew W. Miller, Delphine Courvoisier, Maura D. Iversen, Stéphane Cullati, and Boris Cheval. "Adverse Childhood Experiences, Depressive Symptoms, Functional Dependence, and Physical Activity: A Moderated Mediation Model." Journal of Physical Activity and Health 17, no. 8 (August 1, 2020): 790–99. http://dx.doi.org/10.1123/jpah.2019-0133.
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Background: Adverse childhood experiences, depressive symptoms, and functional dependence are interrelated. However, the mechanisms underlying these associations remain unclear. The authors investigated the potential of depressive symptoms to mediate the effect of adverse childhood experiences on functional dependence in older age and whether physical activity moderated this mediation. Method: Data from 25,775 adults aged 62 (9) years from the Survey of Health Ageing and Retirement in Europe were used in adjusted linear mixed-effects models to test whether depressive symptoms mediated the associations between adverse childhood experiences and functional dependence in activities of daily living (ADL) and instrumental ADL (IADL) and whether physical activity moderated these mediations. Results: The results showed a graded association between the number of adverse childhood experiences (0 vs 1 and 0 vs ≥2) and the number of functional limitations in both ADL (bs = 0.040 and 0.067) and IADL (bs = 0.046 and 0.076). These associations were mediated by depressive symptoms. Physical activity reduced the effect of adverse childhood experiences on depressive symptoms (bs = −0.179 and −0.515) and tempered the effect of depressive symptoms on functional dependence both in ADL (b = −0.073) and IADL (b = −0.100). As a result of these reductions, the effect of adverse childhood experiences and depressive symptoms on functional dependence in ADL (Ps > .081) and IADL (Ps > .528) was nonsignificant in physically active participants. Conclusions: These findings suggest that, after age 50, engaging in physical activity more than once a week protects functional independence from the detrimental effects of adverse childhood experiences and depression. In inactive individuals, the detrimental effects of adverse childhood experiences on functional dependence are mediated by depressive symptoms.
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Schrager, Matthew A., James Hilton, Richard Gould, and Valerie E. Kelly. "Effects of blueberry supplementation on measures of functional mobility in older adults." Applied Physiology, Nutrition, and Metabolism 40, no. 6 (June 2015): 543–49. http://dx.doi.org/10.1139/apnm-2014-0247.
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Limited functional mobility in older adults has been associated with declines in tests of motor, psychomotor, and executive function. Animal studies have demonstrated reversals in indices of motor and psychomotor function via supplementation with polyphenolic-rich foods such as blueberries. The purpose of this study was to examine whether 6 weeks of daily consumption of 2 cups of frozen blueberries affects functional mobility in older adults. Pre- and post-intervention assessments of grip strength, simple reaction time, adaptive gait, and executive function were completed for older adults (age >60 years) partially randomly assigned to a blueberry (BB) supplementation or a carrot juice drink control (CAR) group. Paired t tests were used to assess within-group effects for outcome variables in each supplementation group, and a mixed-model analysis of covariance (ANCOVA) was used to determine group (CAR vs. BB) differences. Mixed-model analysis indicated that the BB group demonstrated significant improvements relative to the CAR group in performance (i.e., number of step errors) of a challenging dual-task adaptive gait test that were independent of differences in gait speed. Within only the BB group, significant improvements were also seen in 3 other measures (i.e., usual gait speed; number of step errors during single-task adaptive gait; and gait speed during dual-task adaptive gait). These preliminary findings support the hypothesis that blueberry supplementation may provide an effective countermeasure to age-related declines in functional mobility and serve as justification for an expansion to larger trials to more fully assess this nonpharmacologic approach to maintaining optimal mobility and independence.
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Greven, Sonja, and Fabian Scheipl. "A general framework for functional regression modelling." Statistical Modelling 17, no. 1-2 (February 2017): 1–35. http://dx.doi.org/10.1177/1471082x16681317.
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Researchers are increasingly interested in regression models for functional data. This article discusses a comprehensive framework for additive (mixed) models for functional responses and/or functional covariates based on the guiding principle of reframing functional regression in terms of corresponding models for scalar data, allowing the adaptation of a large body of existing methods for these novel tasks. The framework encompasses many existing as well as new models. It includes regression for ‘generalized’ functional data, mean regression, quantile regression as well as generalized additive models for location, shape and scale (GAMLSS) for functional data. It admits many flexible linear, smooth or interaction terms of scalar and functional covariates as well as (functional) random effects and allows flexible choices of bases—particularly splines and functional principal components—and corresponding penalties for each term. It covers functional data observed on common (dense) or curve-specific (sparse) grids. Penalized-likelihood-based and gradient-boosting-based inference for these models are implemented in R packages refund and FDboost , respectively. We also discuss identifiability and computational complexity for the functional regression models covered. A running example on a longitudinal multiple sclerosis imaging study serves to illustrate the flexibility and utility of the proposed model class. Reproducible code for this case study is made available online.
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Ashrafi, Abolfazl, Reza-Ali Mohseni, and Tahmures Shiri. "Mutual-implication Interaction between Social Identity and Social System: an Analytic Approach to Social Identity Formation." Education & Self Development 15, no. 4 (December 30, 2020): 50–70. http://dx.doi.org/10.26907/esd15.4.05.
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Social identity formation (SIF) has rarely been addressed, either through analytic methods or on through sociologically and social-psychologically mixed-methods design at multiple levels. In the Iranian context, SIF, especially among youths, is devoid of any theoretical and functional models capable of explaining the effects which have been hypothesized of social system’s SIF functional deficiency. A sample of 445 students from the University of Tehran was selected in the period of 2016-2018, based on a random stratified sampling method. The participants undertook a validated questionnaire (i.e., content and construct validity) measures through expert judgment and PFA, delivered on a tablet. The reliability was r=0.88. A parametric one-sample Student’s t-test and a Friedman test were employed in the analysis which suggested a functional model for SIF. The analysis also supported both the major and minor hypotheses predicting direct effects of Iranian social system’s functional deficiency on reducing the level of their SIF in relation to their social system. Theoretically, the findings suggested an applied model for SIF in a mutually-implicated interaction process with social system along with specific measurement criteria. The model, which has seven parameters, is the product of a social system’s functional requirements, and seems to be influential in SIF formation by social system and can provide insights for social researchers and planners.
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Kalanta, S. "MIXED AND COMPATIBLE FINITE ELEMENTS IN THE ANALYSIS PROBLEM OF ELASTOPLASTIC STRUCTURES." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 2, no. 5 (March 31, 1996): 29–43. http://dx.doi.org/10.3846/13921525.1996.10531546.
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A problem of ideal elastoplastic structures stress-strain field determination is considered The dual general and discrete mathematical models of analysis problem are made on the basis of the extremal energy principles and finite element method. In these models the possible discontinuity of displacements and the dissipation of energy in the place of those discontinuities, also the different external effects (load, initial strains and support settlements) are estimated. At first, on the basis of the mixed functional and mixed finite elements the discrete expressions of fundamental relationships (geometric equations, yield conditions) and the discrete mathematical model of mixed formulation of the problem are made. This mathematical model corresponds to the minimum total energy principle for a kinematically admissible displacements. The dual static formulation of the problem is obtained by Lagrange's multipliers method; this corresponds to the minimum complementary energy principle. The kinematic formulation of the problem is obtained in the case of linear yield conditions. These mathematical models permit to determine the lower values of the stress and displacements of structures. It has shown that the approximation of geometric equations and yield conditions by Bubnov-Galiorkin's collocation method gives the more accurate results.
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Temesgen, Aboma. "Application of Poisson Mixed Combined Models for Identifying Correlations of CD4 Count Progression in HIV Infected TB Patients During ART Treatment Period." International Journal of Statistics and Probability 6, no. 5 (July 24, 2017): 42. http://dx.doi.org/10.5539/ijsp.v6n5p42.
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CD4 count is used to measures the number CD4 cells in the blood mostly during ART treatment to know the risk progression of HIV in the HIV infected patients. This continuously measured CD4 count during the treatment period results longitudinal data having correlation and over dispersion effects. While modeling such data to identify associated factors of change in CD4 count to monitor the progression of HIV most of the study did not considered these two main effects. The main aim of this study was also to consider these two main effect to identify the risk factors CD4 count progression based on 239 HIV infected TB patients who were 18 years old and above taking ART treatment from $1^{st}$ September 2009 to $1^{st}$ July 2014 at Jimma University Specialize Hospital. The result of study showed Poisson normal Gamma combine model which handles correlation and over dispersion effects of CD4 count simultaneously was an appropriate fit of the data among different Poisson mixed combined models considered for the study based on Akaki information criteria (AIC)comparisons. The estimated model depicts linear time and it's interaction effect with functional status category group of the patients have positive effect whereas quadratic time has the negative effect on the progression of CD4 count. The model also showed baseline bedridden and ambulatory functional status group patients has lower average CD4 count measurements in comparison with working functional status group patients counterparts. Therefore, while modeling CD4 count correlation and over dispersion should be taken in to consideration since the CD4 count value was correlated due to repeated measurement and it's variance larger than mean leading to over dispersion. Being at bedridden, ambulatory functional status at baseline in comparison with working functional status group and having quadratic time effects were also the associated risk factors that lowers the CD4 count measurements of the patients during the ART treatment period at the study area.
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Wang, Jiebiao, Pei Wang, Donald Hedeker, and Lin S. Chen. "Using multivariate mixed-effects selection models for analyzing batch-processed proteomics data with non-ignorable missingness." Biostatistics 20, no. 4 (June 24, 2018): 648–65. http://dx.doi.org/10.1093/biostatistics/kxy022.
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Summary In quantitative proteomics, mass tag labeling techniques have been widely adopted in mass spectrometry experiments. These techniques allow peptides (short amino acid sequences) and proteins from multiple samples of a batch being detected and quantified in a single experiment, and as such greatly improve the efficiency of protein profiling. However, the batch-processing of samples also results in severe batch effects and non-ignorable missing data occurring at the batch level. Motivated by the breast cancer proteomic data from the Clinical Proteomic Tumor Analysis Consortium, in this work, we developed two tailored multivariate MIxed-effects SElection models (mvMISE) to jointly analyze multiple correlated peptides/proteins in labeled proteomics data, considering the batch effects and the non-ignorable missingness. By taking a multivariate approach, we can borrow information across multiple peptides of the same protein or multiple proteins from the same biological pathway, and thus achieve better statistical efficiency and biological interpretation. These two different models account for different correlation structures among a group of peptides or proteins. Specifically, to model multiple peptides from the same protein, we employed a factor-analytic random effects structure to characterize the high and similar correlations among peptides. To model biological dependence among multiple proteins in a functional pathway, we introduced a graphical lasso penalty on the error precision matrix, and implemented an efficient algorithm based on the alternating direction method of multipliers. Simulations demonstrated the advantages of the proposed models. Applying the proposed methods to the motivating data set, we identified phosphoproteins and biological pathways that showed different activity patterns in triple negative breast tumors versus other breast tumors. The proposed methods can also be applied to other high-dimensional multivariate analyses based on clustered data with or without non-ignorable missingness.
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Teixeira, Leonardo H., Florencia A. Yannelli, Gislene Ganade, and Johannes Kollmann. "Functional Diversity and Invasive Species Influence Soil Fertility in Experimental Grasslands." Plants 9, no. 1 (January 1, 2020): 53. http://dx.doi.org/10.3390/plants9010053.
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Ecosystem properties can be positively affected by plant functional diversity and compromised by invasive alien plants. We performed a community assembly study in mesocosms manipulating different functional diversity levels for native grassland plants (communities composed by 1, 2 or 3 functional groups) to test if functional dispersion could constrain the impacts of an invasive alien plant (Solidago gigantea) on soil fertility and plant community biomass via complementarity. Response variables were soil nutrients, soil water nutrients and aboveground biomass. We applied linear mixed-effects models to assess the effects of functional diversity and S. gigantea on plant biomass, soil and soil water nutrients. A structural equation model was used to evaluate if functional diversity and invasive plants affect soil fertility directly or indirectly via plant biomass and soil pH. Invaded communities had greater total biomass but less native plant biomass than uninvaded ones. While functional diversity increased nutrient availability in the soil solution of uninvaded communities, invasive plants reduced nutrient concentration in invaded soils. Functional diversity indirectly affected soil water but not soil nutrients via plant biomass, whereas the invader reduced native plant biomass and disrupted the effects of diversity on nutrients. Moreover, invasive plants reduced soil pH and compromised phosphate uptake by plants, which can contribute to higher phosphate availability and its possible accumulation in invaded soils. We found little evidence for functional diversity to constrain invasion impacts on nutrients and plant biomass. Restoration of such systems should consider other plant community features than plant trait diversity to reduce establishment of invasive plants.
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Ge, Tian, Avram J. Holmes, Randy L. Buckner, Jordan W. Smoller, and Mert R. Sabuncu. "Heritability analysis with repeat measurements and its application to resting-state functional connectivity." Proceedings of the National Academy of Sciences 114, no. 21 (May 8, 2017): 5521–26. http://dx.doi.org/10.1073/pnas.1700765114.
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Heritability, defined as the proportion of phenotypic variation attributable to genetic variation, provides important information about the genetic basis of a trait. Existing heritability analysis methods do not discriminate between stable effects (e.g., due to the subject’s unique environment) and transient effects, such as measurement error. This can lead to misleading assessments, particularly when comparing the heritability of traits that exhibit different levels of reliability. Here, we present a linear mixed effects model to conduct heritability analyses that explicitly accounts for intrasubject fluctuations (e.g., due to measurement noise or biological transients) using repeat measurements. We apply the proposed strategy to the analysis of resting-state fMRI measurements—a prototypic data modality that exhibits variable levels of test–retest reliability across space. Our results reveal that the stable components of functional connectivity within and across well-established large-scale brain networks can be considerably heritable. Furthermore, we demonstrate that dissociating intra- and intersubject variation can reveal genetic influence on a phenotype that is not fully captured by conventional heritability analyses.
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Yen, Sheng-Che, Marie B. Corkery, Kevin K. Chui, Justin Manjourides, Ying-Chih Wang, and Linda J. Resnik. "Risk Adjustment for Lumbar Dysfunction: Comparison of Linear Mixed Models With and Without Inclusion of Between-Clinic Variation as a Random Effect." Physical Therapy 95, no. 12 (December 1, 2015): 1692–702. http://dx.doi.org/10.2522/ptj.20140444.
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BackgroundValid comparison of patient outcomes of physical therapy care requires risk adjustment for patient characteristics using statistical models. Because patients are clustered within clinics, results of risk adjustment models are likely to be biased by random, unobserved between-clinic differences. Such bias could lead to inaccurate prediction and interpretation of outcomes.PurposeThe purpose of this study was to determine if including between-clinic variation as a random effect would improve the performance of a risk adjustment model for patient outcomes following physical therapy for low back dysfunction.DesignThis was a secondary analysis of data from a longitudinal cohort of 147,623 patients with lumbar dysfunction receiving physical therapy in 1,470 clinics in 48 states of the United States.MethodsThree linear mixed models predicting patients' functional status (FS) at discharge, controlling for FS at intake, age, sex, number of comorbidities, surgical history, and health care payer, were developed. Models were: (1) a fixed-effect model, (2) a random-intercept model that allowed clinics to have different intercepts, and (3) a random-slope model that allowed different intercepts and slopes for each clinic. Goodness of fit, residual error, and coefficient estimates were compared across the models.ResultsThe random-effect model fit the data better and explained an additional 11% to 12% of the between-patient differences compared with the fixed-effect model. Effects of payer, acuity, and number of comorbidities were confounded by random clinic effects.LimitationsModels may not have included some variables associated with FS at discharge. The clinics studied may not be representative of all US physical therapy clinics.ConclusionsRisk adjustment models for functional outcome of patients with lumbar dysfunction that control for between-clinic variation performed better than a model that does not.
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Poulos, Helen M., Kate E. Miller, Ross Heinemann, Michelle L. Kraczkowski, Adam W. Whelchel, and Barry Chernoff. "Dam Removal Effects on Benthic Macroinvertebrate Dynamics: A New England Stream Case Study (Connecticut, USA)." Sustainability 11, no. 10 (May 21, 2019): 2875. http://dx.doi.org/10.3390/su11102875.
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Dam removal is an increasingly common stream restoration tool. Yet, removing dams from small streams also represents a major disturbance to rivers that can have varied impacts on environmental conditions and aquatic biota. We examined the effects of dam removal on the structure, function, and composition of benthic macroinvertebrate (BMI) communities in a temperate New England stream. We examined the effects of dam removal over the dam removal time-series using linear mixed effects models, autoregressive models, non-metric multidimensional scaling, and indicator and similarity analyses. The results indicated that the dam removal stimulated major shifts in BMI community structure and composition above and below the dam, and that the BMI communities are becoming more similar over time. The mixed model analysis revealed that BMI functional groups and diversity were significantly influenced by sample site and several BMI groups also experienced significant interactions between site and dam stage (P < 0.05), while the multivariate analyses revealed that community structure continues to differ among sites, even three years after dam removal. Our findings indicate that stream restoration through dam removal can have site-specific influences on BMI communities, that interactions among BMI taxa are important determinants of the post-dam removal community, and that the post-dam-removal BMI community continues to be in a state of reorganization.
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Marshall, B. E., and C. Marshall. "A model for hypoxic constriction of the pulmonary circulation." Journal of Applied Physiology 64, no. 1 (January 1, 1988): 68–77. http://dx.doi.org/10.1152/jappl.1988.64.1.68.
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The detailed anatomic and biodynamic data provided for the cat lung by Zhuang et al. (J. Appl. Physiol. 55: 1341-1348, 1983) allowed pressure-flow curves for the normal lung to be generated. This model has been modified to permit the stimulation of the pressure and flow distribution effects of hypoxic pulmonary vasoconstriction for a two-compartment lung and generalized to allow comparison with the experimental results from dogs (and probably other species). Hypoxic pulmonary vasoconstriction is simulated by reduction of the initial diameter of the smallest six orders of pulmonary arteries. Expressions are presented that relate the alveolar and mixed-venous O2 tensions to a graded constriction of these vessels. In addition, the diameter of the capillary sheet and the six small arteries is defined with a maximum diameter at a transmural pressure of 20 cmH2O. Pressure-flow curves are derived for any combination of alveolar and mixed-venous O2 tension, alveolar and pleural pressure, left atrial pressure, and hematocrit. The two-compartment model is solved by an iterative procedure to identify the distribution of the flow and the resulting pulmonary arterial pressure when the compartments differ by size, hypoxic constriction, or other imposed conditions. The results of the model are compared with those from a variety of experimental preparations. It is concluded that the model is useful for identifying the quantitative causes of changes in the response to hypoxic pulmonary vasoconstriction and for the exploration of the functional influence of mechanical properties of the vasculature.
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Niesters, Marieke, Najmeh Khalili-Mahani, Christian Martini, Leon Aarts, Joop van Gerven, Mark A. van Buchem, Albert Dahan, and Serge Rombouts. "Effect of Subanesthetic Ketamine on Intrinsic Functional Brain Connectivity." Anesthesiology 117, no. 4 (October 1, 2012): 868–77. http://dx.doi.org/10.1097/aln.0b013e31826a0db3.
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Background The influence of psychoactive drugs on the central nervous system has been investigated with positron emission tomography and task-related functional magnetic resonance imaging. However, it is not known how these drugs affect the intrinsic large-scale interactions of the brain (resting-state functional magnetic resonance imaging connectivity). In this study, the effect of low-dose S(+)-ketamine on intrinsic brain connectivity was investigated. Methods Twelve healthy, male volunteers received a 2-h intravenous S(+)-ketamine infusion (first hour 20 mg/70 kg, second hour 40 mg/70 kg). Before, during, and after S(+)-ketamine administration, resting-state brain connectivity was measured. In addition, heat pain tests were performed between imaging sessions to determine ketamine-induced analgesia. A mixed-effects general linear model was used to determine drug and pain effects on resting-state brain connectivity. Results Ketamine increased the connectivity most importantly in the cerebellum and visual cortex in relation to the medial visual network. A decrease in connectivity was observed in the auditory and somatosensory network in relation to regions responsible for pain sensing and the affective processing of pain, which included the amygdala, insula, and anterior cingulate cortex. Connectivity variations related to fluctuations in pain scores were observed in the anterior cingulate cortex, insula, orbitofrontal cortex, and the brainstem, regions involved in descending inhibition of pain. Conclusions Changes in connectivity were observed in the areas that explain ketamine's pharmacodynamic profile with respect to analgesia and psychedelic and other side effects. In addition, pain and ketamine changed brain connectivity in areas involved in endogenous pain modulation.
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Zong, Jacky, and Danik M. Martirosyan. "Anticancer effects of garlic and garlic-derived bioactive compounds and its potential status as functional food." Bioactive Compounds in Health and Disease 1, no. 2 (July 2, 2018): 16. http://dx.doi.org/10.31989/bchd.v1i2.530.
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Background: Garlic, or Allium savitum, has long been used to treat various diseases, including cancer. The anticancer effects of garlic are linked to the several garlic-derived organosulfur compounds, such as allicin, ajoene, DAS, DADS, DATS, and SAMC. Animal and in vitro studies have demonstrated that garlic bioactive compounds may prevent cancer through mechanisms such as inducing cell cycle arrest, promoting apoptosis, and inhibiting angiogenesis in different cancer cells. Observational studies, including case-control and cohort studies, have been conducted to confirm the protective effect against colorectal, gastric, and other cancers associated with garlic-derived bioactive compounds and raw garlic consumption, but results have been mixed. Analysis of cell and animal model studies and epidemiological studies using the FDA’s evidence-based review system for health claims and FFC’s proposed standard for evaluating and developing functional food, it has been concluded that garlic cannot yet be considered as a functional food primarily due to the inconclusive data from observational studies and insufficient evidence from randomized clinical trials. Keywords: Garlic, cancer, allicin, bioactive compound, functional food
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Buotte, Polly C., Charles D. Koven, Chonggang Xu, Jacquelyn K. Shuman, Michael L. Goulden, Samuel Levis, Jessica Katz, et al. "Capturing functional strategies and compositional dynamics in vegetation demographic models." Biogeosciences 18, no. 14 (July 30, 2021): 4473–90. http://dx.doi.org/10.5194/bg-18-4473-2021.
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Abstract. Plant community composition influences carbon, water, and energy fluxes at regional to global scales. Vegetation demographic models (VDMs) allow investigation of the effects of changing climate and disturbance regimes on vegetation composition and fluxes. Such investigation requires that the models can accurately resolve these feedbacks to simulate realistic composition. Vegetation in VDMs is composed of plant functional types (PFTs), which are specified according to plant traits. Defining PFTs is challenging due to large variability in trait observations within and between plant types and a lack of understanding of model sensitivity to these traits. Here we present an approach for developing PFT parameterizations that are connected to the underlying ecological processes determining forest composition in the mixed-conifer forest of the Sierra Nevada of California, USA. We constrain multiple relative trait values between PFTs, as opposed to randomly sampling within the range of observations. An ensemble of PFT parameterizations are then filtered based on emergent forest properties meeting observation-based ecological criteria under alternate disturbance scenarios. A small ensemble of alternate PFT parameterizations is identified that produces plausible forest composition and demonstrates variability in response to disturbance frequency and regional environmental variation. Retaining multiple PFT parameterizations allows us to quantify the uncertainty in forest responses due to variability in trait observations. Vegetation composition is a key emergent outcome from VDMs and our methodology provides a foundation for robust PFT parameterization across ecosystems.
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Wang, Danni, Zhi-Jin Hou, Jing Ni, Lu Tian, Xin Zhang, Hao-Yang Chi, and Adam Zhao. "The Effect of Perfectionism on Career Adaptability and Career Decision-Making Difficulties." Journal of Career Development 47, no. 4 (October 11, 2018): 469–83. http://dx.doi.org/10.1177/0894845318803192.
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This study investigated categorization of perfectionism subtypes for Chinese undergraduates and the effects of perfectionism subtypes on career outcomes based on two prominent, competing models of perfectionism, the tripartite model and 2 × 2 model. Indices of career outcome were defined with career adaptability (positive) and career decision-making difficulties (negative). The results of both cluster analysis and latent profile analysis coincided with the four-subtype structure of the 2 × 2 model. The result of Bolck–Croon–Hagenaars modeling indicated that the pure high standard subtypes were the most functional while pure discrepancy subtypes were most dysfunctional. Mixed perfectionism subtypes were identified as having high career adaptability but also high risk for career decision-making while nonperfectionism subtypes possess low career decision-making difficulties but also low career adaptability. Based on these findings for perfectionism subtypes, we extrapolate practical recommendations for how this information could be pertinent to career counseling.
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Hong, Eun Pyo, Seong Gu Heo, and Ji Wan Park. "The Liability Threshold Model for Predicting the Risk of Cardiovascular Disease in Patients with Type 2 Diabetes: A Multi-Cohort Study of Korean Adults." Metabolites 11, no. 1 (December 24, 2020): 6. http://dx.doi.org/10.3390/metabo11010006.
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Personalized risk prediction for diabetic cardiovascular disease (DCVD) is at the core of precision medicine in type 2 diabetes (T2D). We first identified three marker sets consisting of 15, 47, and 231 tagging single nucleotide polymorphisms (tSNPs) associated with DCVD using a linear mixed model in 2378 T2D patients obtained from four population-based Korean cohorts. Using the genetic variants with even modest effects on phenotypic variance, we observed improved risk stratification accuracy beyond traditional risk factors (AUC, 0.63 to 0.97). With a cutoff point of 0.21, the discrete genetic liability threshold model consisting of 231 SNPs (GLT231) correctly classified 87.7% of 2378 T2D patients as high or low risk of DCVD. For the same set of SNP markers, the GLT and polygenic risk score (PRS) models showed similar predictive performance, and we observed consistency between the GLT and PRS models in that the model based on a larger number of SNP markers showed much-improved predictability. In silico gene expression analysis, additional information was provided on the functional role of the genes identified in this study. In particular, HDAC4, CDKN2B, CELSR2, and MRAS appear to be major hubs in the functional gene network for DCVD. The proposed risk prediction approach based on the liability threshold model may help identify T2D patients at high CVD risk in East Asian populations with further external validations.
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Brogan, David M., Christopher J. Dy, Tony Y. Lee, Dana Rioux-Forker, Jason Wever, and Fraser J. Leversedge. "Histologic and Functional Outcomes of Conduit Wrapping for Peripheral Nerve Repair: Early Results in a Rat Model." Journal of Reconstructive Microsurgery 37, no. 07 (January 31, 2021): 559–65. http://dx.doi.org/10.1055/s-0040-1722762.
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Abstract Background The concept of utilizing a nerve conduit for augmentation of a primary nerve repair has been advocated as a method to prevent neural scarring and decrease adhesions. Despite clinical use, little is known about the effects of a nerve conduit wrapped around a primary repair. To better understand this, we investigated the histologic and functional effects of use of a nerve conduit wrapped around a rat sciatic nerve repair without tension. Methods Twenty Lewis' rats were divided into two groups of 10 rats each. In each group, unilateral sciatic nerve transection and repair were performed, with the opposite limb utilized as a matched control. In the first group, direct repair alone was performed; in the second group, this repair was augmented with a porcine submucosa conduit wrapped around the repair site. Sciatic functional index (SFI) was measured at 6 weeks with walking track analysis in both groups. Nonsurvival surgeries were then performed in all animals to harvest both the experimental and control nerves to measure histomorphometric parameters of recovery. Histomorphometric parameters assessed included total number of neurons, nerve fiber density, nerve fiber width, G-ratio, and percentage of debris. Unpaired t-test was used to compare outcomes between the two groups. Results All nerves healed uneventfully but compared with direct repair; conduit usage was associated with greater histologic debris, decreased axonal density, worse G-ratio, and worse SFI. No significant differences were found in total axon count or gastrocnemius weight. Conclusion In the absence of segmental defects, conduit wrapping primary nerve repairs seem to be associated with worse functional and mixed histologic outcomes at 6 weeks, possibly due to debris from conduit resorption. While clinical implications are unclear, more basic science and clinical studies should be performed prior to widespread adoption of this practice.
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Domínguez Alvarado, Axel Fernando, and Alberto Díaz Díaz. "A Mixed Stress/Displacement Approach Model of Homogeneous Shells for Elastodynamic Problems." Mathematical Problems in Engineering 2020 (January 13, 2020): 1–15. http://dx.doi.org/10.1155/2020/5429615.
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This paper presents the development of a model of homogeneous, moderately thick shells for elastodynamic problems. The model is obtained by adapting and modifying SAM-H model (stress approach model of homogeneous shells) developed by Domínguez Alvarado and Díaz in (2018) for static problems. In the dynamic version of SAM-H presented herein, displacements and stresses are approximated by polynomials of the out-of-plane coordinate. The stress approximation coincides with the static version of SAM-H when dynamic effects are neglected. The generalized forces and displacements appearing in the approximations are the same as those involved in a classical, moderately thick shell model (CS model) but the stress approximation adopted herein is more complex: the 3D motion equations and the stress boundary conditions at the faces of the shell are verified. The generalized motion and constitutive equations of dynamic SAM-H model are obtained by applying a variant of Euler–Lagrange equation which includes pertinently Hellinger–Reissner functional. In the constitutive equations, Poisson’s effect of out-of-plane normal stresses on in-plane strains is not ignored; this is one important feature of SAM-H. To test the accuracy of dynamic SAM-H model, the following structures were considered: a hollow sphere and a catenoid. In each case, eigenfrequencies are first calculated and then a frequency analysis is performed applying a harmonic load. The results are compared to those of a CS model, MITC6 (mixed interpolation of tensorial components with 6 nodes per element) shell element calculations, and solid finite element computations. In the two problems, CS, MITC6, and dynamic SAM-H models yield accurate eigenfrequencies and eigenmodes. Nevertheless, the frequency analysis performed in each case showed that dynamic SAM-H provides much more accurate amplitudes of stresses and displacements than the CS model and the MITC6 shell finite element technique.
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Matar, Samir F. "Electronic Structure and Chemical Bonding within MgB2 and Related Borides from First Principles." Zeitschrift für Naturforschung B 63, no. 6 (June 1, 2008): 673–80. http://dx.doi.org/10.1515/znb-2008-0613.
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The electronic structures of actual and hypothetical binary borides AB2 (A = Al, Mg, Li, Be, Ca) and of mixed hypothetical phases A'MgB4 (A' = Al, Li) are obtained and analyzed within the density functional theory using pseudo-potential and all-electron methods (VASP and ASW) in order to address the changes in the electronic structure within the high-temperature superconductor MgB2 by modeling isoelectronic and n/p-doping effects. From the properties of quantum mixing between respective valence states and of chemical bonding we propose an analysis of the high-temperature superconductivity within the two models, the classical one of Bardeen, Cooper and Schrieffer (BCS) and the hole superconductivity model, which is based on experimental and calculated results from the literature.
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Rab, M. A., S. Chandra, P. D. Fisher, N. J. Robinson, M. Kitching, C. D. Aumann, and M. Imhof. "Modelling and prediction of soil water contents at field capacity and permanent wilting point of dryland cropping soils." Soil Research 49, no. 5 (2011): 389. http://dx.doi.org/10.1071/sr10160.
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Field capacity (FC) and permanent wilting point (PWP) are two critical input parameters required in various biophysical models. There are limited published data on FC and PWP of dryland cropping soils across north-western Victoria. Direct measurements of FC and PWP are time-consuming and expensive. Reliable prediction of FC and PWP from their functional relationships with routinely measured soil properties can help to circumvent these constraints. This study provided measured data on FC using undisturbed samples and PWP as functions of geomorphological unit, soil type, and soil texture class for dryland cropping soils of north-western Victoria. We used a balanced, nested sampling strategy and developed functional relationships of FC and PWP with routinely measured soil properties using residual maximum likelihood based mixed-effects regression modelling. Using the data, we also tested the adequacy of nine published pedotransfer functions (PTFs) in predicting FC and PWP. Significant differences were observed among the three soil types and nine texture classes for most soil properties. FC and PWP were higher for Grey Vertosols (FC 43.7% vol, PWP 29.1% vol) than Hypercalcic Calcarosols (38.4%, 23.5%) and Red Sodosols (20.2%, 9.2%). Of the several functional relationships developed for prediction of FC and PWP, a quadratic single-predictor model based on dg (geometric mean particle size diameter) performed better than other models for both FC and PWP. It was nearly bias-free, with a root mean square error (RMSE) of 3.18% vol and an R2 of 93% for FC, and RMSE 3.47% vol and R2 89% for PWP. Another useful model for FC was a slightly biased, two-predictor quadratic model based on clay and silt, with RMSE 3.14% vol and R2 94%. For PWP, two other possibly useful, though slightly biased, models included a single-predictor quadratic model based on clay (RMSE 3.45% vol, R2 89%) and a three-predictor model based on clay, silt, and σg (geometric standard deviation of particle size diameter) (RMSE 3.27% vol, R2 90%). We observed a strong quadratic relationship of FC with PWP (RMSE 1.61% vol, R2 98%). This suggests the possibility to further improve the prediction of FC indirectly through PWP. These predictive models for FC and PWP, though developed for the dryland cropping soils of north-western Victoria, may be applicable to other regions with similar soil and climatic conditions. Some validation is desirable before these models are confidently applied in a new situation. Of the nine published PTFs, the multiple linear regression and artificial neural network based NTh5 for FC and NTh3 and CAM for PWP performed better on our data for the prediction of FC and PWP. The root mean square deviation of these PTFs, for both FC and PWP, was higher than the RMSE of our models. Our models are therefore likely to perform better under the dryland cropping soils of north-western Victoria than these PTFs. As a safeguard against arriving at optimistic inferences, we suggest that the modelling of functional relationships needs to account for the hierarchical structure of the sampling design using appropriate mixed effects regression models.
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Song, Yi Mei, and Xiao Qing Shang. "Image Denoising Based on Reaction-Diffusion Equation and Curvelet Transform." Applied Mechanics and Materials 40-41 (November 2010): 554–59. http://dx.doi.org/10.4028/www.scientific.net/amm.40-41.554.
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To reduce the pseudo-Gibbs effects and the “curvelet like” aliased curves resulted from using curvelet transform for image denoising, we proposed a noise removal method which combines computational harmonic analysis and variation. Firstly, we presented a nonlinear reaction-diffusion digital filter based on Nordström energy functional. For effectively overcoming speckle noise due to the reaction-diffusion process of digital filtering and the ill-posed of diffusion coefficient, we gave an improved model by introducing curvelet smoothing operator and the new diffusion function. Numerical results show that the model is not only for images with Gaussian noise, Salt&pepper noise or Speckle noise, but also suitable for mixed noise, the denoised image has higher PSNR and good visual effect.
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Liu, Ziyue, and Wensheng Guo. "Functional mixed effects models." Wiley Interdisciplinary Reviews: Computational Statistics 4, no. 6 (August 24, 2012): 527–34. http://dx.doi.org/10.1002/wics.1226.
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Guo, Wensheng. "Functional Mixed Effects Models." Biometrics 58, no. 1 (March 2002): 121–28. http://dx.doi.org/10.1111/j.0006-341x.2002.00121.x.
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Aguilar-Trejo, Carlos Martín, Guillermo Luna-Nevárez, Javier Rolando Reyna-Granados, Ricardo Zamorano-Algandar, Javier Alonso Romo-Rubio, Miguel Ángel Sánchez-Castro, R. Mark Enns, Scott E. Speidel, Milton G. Thomas, and Pablo Luna-Nevárez. "Polymorphisms associated with the number of live-born piglets in sows infected with the PRRS virus in southern Sonora Mexico." Revista Mexicana de Ciencias Pecuarias 11, no. 3 (September 21, 2020): 828–47. http://dx.doi.org/10.22319/rmcp.v11i3.5002.
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The porcine reproductive and respiratory syndrome (PRRS) is a viral disease that decreases the reproductive performance in breeding sows and leads to economic losses to the swine industry. The objective of the present study was to identify single nucleotide polymorphisms (SNP) associated to the number of live-born piglets in the first (LBP1) and second birth (LBP2) in breeding sows exposed to PRRS virus. The study included 100 pregnant females of the Landrace(¾)/ Yorkshire(¼) line, 75 of which were infected with the PRRS virus and 25 were free of PRRS. Individual blood samples (6-8 drops) were obtained and spotted onto FTA cards and subsequently processed for DNA extraction, which was genotyped using a 10,000 SNP chip for genomic profile. Resulting genotypes were analyzed using a multi-locus mixed model that detected three SNP associated to LBP1 and five SNP associated to LBP2 (P<0.001). These eight SNP were validated using an associative mixed effects model which included the terms genotype and age of dam as fixed effects, and sire as random effect. Allele substitution effects were estimated using the same model including the term genotype as covariate. The SNP rs81276080, rs81334603 and rs80947173 were associated to LBP1 (P<0.001), whereas the SNP rs81364943, rs80859829, rs80895640, rs80893794 and rs81245908 were associated to LBP2 (P<0.001). Only two SNP were in functional chromosomal regions and the remainder SNP were within an intergenic position. In conclusion, these results suggest the existence of gene variants associated with the reproductive performance of sows infected with the PRRS virus.
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Hirl, Regina T., Hans Schnyder, Ulrike Ostler, Rudi Schäufele, Inga Schleip, Sylvia H. Vetter, Karl Auerswald, et al. "The <sup>18</sup>O ecohydrology of a grassland ecosystem – predictions and observations." Hydrology and Earth System Sciences 23, no. 6 (June 14, 2019): 2581–600. http://dx.doi.org/10.5194/hess-23-2581-2019.
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Abstract. The oxygen isotope composition (δ18O) of leaf water (δ18Oleaf) is an important determinant of environmental and physiological information found in biological archives, but the system-scale understanding of the propagation of the δ18O of rain through soil and xylem water to δ18Oleaf has not been verified for grassland. Here we report a unique and comprehensive dataset of fortnightly δ18O observations in soil, stem and leaf waters made over seven growing seasons in a temperate, drought-prone, mixed-species grassland. Using the ecohydrology part of a physically based, 18O-enabled soil–plant–atmosphere transfer model (MuSICA), we evaluated our ability to predict the dynamics of δ18O in soil water, the depth of water uptake, and the effects of soil and atmospheric moisture on 18O enrichment of leaf water (Δ18Oleaf) in this ecosystem. The model accurately predicted the δ18O dynamics of the different ecosystem water pools, suggesting that the model generated realistic predictions of the vertical distribution of soil water and root water uptake dynamics. Observations and model predictions indicated that water uptake occurred predominantly from shallow (<20 cm) soil depths throughout dry and wet periods in all years, presumably due (at least in part) to the effects of high grazing pressure on root system turnover and placement. Δ18Oleaf responded to both soil and atmospheric moisture contents and was best described in terms of constant proportions of unenriched and evaporatively enriched water (two-pool model). The good agreement between model predictions and observations is remarkable as model parameters describing the relevant physical features or functional relationships of soil and vegetation were held constant with one single value for the entire mixed-species ecosystem.
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Möller, Gregor, and Daniel Landskron. "Atmospheric bending effects in GNSS tomography." Atmospheric Measurement Techniques 12, no. 1 (January 3, 2019): 23–34. http://dx.doi.org/10.5194/amt-12-23-2019.
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Abstract. In Global Navigation Satellite System (GNSS) tomography, precise information about the tropospheric water vapor distribution is derived from integral measurements like ground-based GNSS slant wet delays (SWDs). Therefore, the functional relation between observations and unknowns, i.e., the signal paths through the atmosphere, have to be accurately known for each station–satellite pair involved. For GNSS signals observed above a 15∘ elevation angle, the signal path is well approximated by a straight line. However, since electromagnetic waves are prone to atmospheric bending effects, this assumption is not sufficient anymore for lower elevation angles. Thus, in the following, a mixed 2-D piecewise linear ray-tracing approach is introduced and possible error sources in the reconstruction of the bended signal paths are analyzed in more detail. Especially if low elevation observations are considered, unmodeled bending effects can introduce a systematic error of up to 10–20 ppm, on average 1–2 ppm, into the tomography solution. Thereby, not only the ray-tracing method but also the quality of the a priori field can have a significant impact on the reconstructed signal paths, if not reduced by iterative processing. In order to keep the processing time within acceptable limits, a bending model is applied for the upper part of the neutral atmosphere. It helps to reduce the number of processing steps by up to 85 % without significant degradation in accuracy. Therefore, the developed mixed ray-tracing approach allows not only for the correct treatment of low elevation observations but is also fast and applicable for near-real-time applications.
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Atterwill, Christopher K., Wendy J. Davies, and Michael A. Kyriakides. "An Investigation of Aluminium Neurotoxicity using some In Vitro Systems." Alternatives to Laboratory Animals 18, no. 1_part_1 (November 1990): 181–90. http://dx.doi.org/10.1177/026119299001800119.1.
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It has been shown that acute exposure in vitro to high concentrations of aluminium chloride does not appear to perturb neural function in terms of the electrophysiological properties of lower vertebrate leech neurones. Longer term exposure in vitro, however, both non-specifically inhibits cellular differentiation and also produces neural cytotoxicity in the rat midbrain micromass, mixed cell culture model. Furthermore, previous studies from this laboratory have demonstrated a reduction of cholinergic neuronal function in brain organotypic reaggregate cultures following long-term, but not short-term, exposure. More-immature neural cells appear to be most sensitive to the effects of aluminium. Relating these data to the tiered in vitro test system for neurotoxicants previously proposed by Atterwill (13), it is apparent that the neurotoxic effects of aluminium are detectable in a first-stage procedure using the micromass culture model, but not following acute exposure in freshly isolated, ex vivo leech neurones. Functional cholinergic toxicity was also detected in the organotypic reaggregate cultures proposed as a second level screen.
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Fedecostante, Massimiliano, Graziano Onder, Paolo Eusebi, Giuseppina Dell’Aquila, Elisa Zengarini, Barbara Carrieri, Ester Manes Gravina, et al. "Predictors of Functional Decline in Nursing Home Residents: The Shelter Project." Journals of Gerontology: Series A 75, no. 8 (December 20, 2019): 1600–1605. http://dx.doi.org/10.1093/gerona/glz296.
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Abstract Background The aim of our study was to identify independent predictors of functional decline in older nursing home (NH) residents, taking into account both resident and facility characteristics. Methods Longitudinal observational study involving 1,760 older (≥65 y) residents of NH participating in the SHELTER* study (57 NH in eight countries). All residents underwent a comprehensive geriatric assessment using the interRAI LTCF. Functional decline was defined as an increase of at least one point in the MDS Long Form ADL scale during a 1 year follow-up. Facility and country effects were taken into account. Results During the study period 891 (50.6%), NH residents experienced ADL decline. Residents experiencing ADL decline were older, had lower disability at baseline, were more frequently affected by severe dementia and by urinary incontinence, and used more antipsychotics. In the mixed-effect logistic regression model, factors independently associated with a higher risk of functional decline were dementia and urinary incontinence, whereas the presence of a geriatrician was a protective factor. Conclusions Both resident and facility characteristics are associated with the risk of functional decline in NH residents. Increasing the quality of healthcare by involving a geriatrician in residents’ care might be an important strategy to improve the outcome of this vulnerable population.
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Xie, Hua, Javier Gonzalez-Castillo, Daniel A. Handwerker, Peter A. Bandettini, Vince D. Calhoun, Gang Chen, Eswar Damaraju, Xiangyu Liu, and Sunanda Mitra. "Time-varying whole-brain functional network connectivity coupled to task engagement." Network Neuroscience 3, no. 1 (January 2019): 49–66. http://dx.doi.org/10.1162/netn_a_00051.
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Brain functional connectivity (FC), as measured by blood oxygenation level-dependent (BOLD) signal, fluctuates at the scale of 10s of seconds. It has recently been found that whole-brain dynamic FC (dFC) patterns contain sufficient information to permit identification of ongoing tasks. Here, we hypothesize that dFC patterns carry fine-grained information that allows for tracking short-term task engagement levels (i.e., 10s of seconds long). To test this hypothesis, 25 subjects were scanned continuously for 25 min while they performed and transitioned between four different tasks: working memory, visual attention, math, and rest. First, we estimated dFC patterns by using a sliding window approach. Next, we extracted two engagement-specific FC patterns representing active engagement and passive engagement by using k-means clustering. Then, we derived three metrics from whole-brain dFC patterns to track engagement level, that is, dissimilarity between dFC patterns and engagement-specific FC patterns, and the level of brainwide integration level. Finally, those engagement markers were evaluated against windowed task performance by using a linear mixed effects model. Significant relationships were observed between abovementioned metrics and windowed task performance for the working memory task only. These findings partially confirm our hypothesis and underscore the potential of whole-brain dFC to track short-term task engagement levels.
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Li, Jiaqi, Yongguang Zhang, Zhimin Yang, Jingxian Zhang, Ren Lin, and Daoshu Luo. "Salidroside promotes sciatic nerve regeneration following combined application epimysium conduit and Schwann cells in rats." Experimental Biology and Medicine 245, no. 6 (February 13, 2020): 522–31. http://dx.doi.org/10.1177/1535370220906541.
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Schwann cell and nerve conduit are crucial for nerve regeneration and re-myelination after peripheral nerves injury. To investigate the effects of Salidroside on autogenous epimysium conduit mixed with BD matrigel and RSC96 Schwann cells on an animal model with 5 mm sciatic nerve defect injury in rat, motor function, muscle reinnervation, immunohistochemical staining, retrograded tracing and Western blot were used in this study. The results showed that Salidroside enhanced the compound effects of epimysium conduit mixed with BD matrigel and RSC96 Schwann cells to improve the sciatic functional index and the gastrocnemius muscle weight ratio, which were better than EPM group at 8 weeks and 12 weeks post operation. Immunofluorescence and Western blot results of P75NTR showed that Salidroside improved the sciatic nerve regeneration, and retrograded tracing of CTB-Alexa 488 also supported that Salidroside was better to promote CTB tracer transporting from the distal nerve defect to the ipsilateral dorsal root ganglion and ventral horn of L3-L5 spinal cord on post-operation 8 weeks and 12 weeks. Our results demonstrated that Salidroside improved the effect of autogenous epimysium conduit mixed with BD matrigel and RSC96 Schwann cells on sciatic nerve regeneration in our study. Impact statement Peripheral nerve injury and regeneration remain a major challenge. Although nerve conduit and Schwann cells have been used to study the nerve regeneration, our results demonstrated that Salidroside improved the regenerative effect in a rat model with sciatic nerve injury model, following a combined application of autogenous epimysium conduit mixed with Schwann cells. Different concentrations of Salidroside combining autogenous epimysium conduit and Schwann cells were applied to compare the epimysium conduit group and the epimysium conduit combining Schwann cells group. Based on the results of motor function and muscle reinnervation evaluation, as well as neuronal tracing and expression of P75NTR, our study for the first time suggests that Salidroside may improve the regeneration effect on the sciatic nerve following a combined application of epimysium conduit and RSC96 Schwann cells in rats.
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Gugushvili, Alexi. "Economic Liberalization and Intergenerational Mobility in Occupational Status." Comparative Sociology 14, no. 6 (December 8, 2015): 790–820. http://dx.doi.org/10.1163/15691330-12341368.
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One of the most important components of post-socialist transition has been economic liberalization. This article inquiries into how the latter is associated with intergenerational mobility in occupational status. Using European Values Studies (evs) data from the nationally representative samples for a large number of post-socialist societies, the European Bank for Reconstruction and Development (ebrd) index of economic liberalization, and multilevel mixed-effects linear regressions, I test the “meritocracy as functional imperative” perspective which implies that life chances depend on the efficiency considerations of liberalized economy. The derived results are robust to alternative model and variable specifications and suggest that economic liberalization explains cross-national differences in intergenerational status reproduction, and is better suited for macro-sociological models of mobility in occupational status than other conventional contextual explanations such as economic development and income inequality.
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Buhmann, Alexander, and Diana Ingenhoff. "Advancing the country image construct from a public relations perspective." Journal of Communication Management 19, no. 1 (February 2, 2015): 62–80. http://dx.doi.org/10.1108/jcom-11-2013-0083.
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Purpose – The purpose of this paper is to develop and test a new model for the measurement of the constitution and effects of the country image as a central target construct in international public relations. Design/methodology/approach – The authors combine concepts from reputation management (Eisenegger and Imhof, 2008; Ingenhoff and Sommer, 2007), national identity theory (Smith, 1987), and attitude theory (Ajzen and Fishbein, 1980) to derive a four-dimensional model, conceptualizing country images as stakeholder attitudes toward a nation and its state, comprising specific beliefs and general feelings in a functional, normative, aesthetic, and emotional dimension. Furthermore, the authors develop a path model to analyze the country image’s effect on stakeholder behavior. This model is operationalized and tested in a survey regarding the country image of the USA and its effects on travel behavior. Findings – Results show how functional, normative and aesthetic image dimensions vary in affecting the formation of the affective image component. It is also demonstrated how the affective image di-mension acts as a mediator in the image’s effect on stakeholder behavior. Practical implications – For international public relations and public diplomacy practice the developed model supplies a new approach for country image analyses which will serve and improve the development and evaluation of cross-national communication strategies. Originality/value – The paper introduces a new theory-grounded approach to clarify the dimensionality of the country image construct. It is the first to operationalize cognitive and affective dimensions of the country image by combining formative and reflective indicators in a mixed specified construct.
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Adindu, Chinonso Blessing, Emeka Emmanuel Oguzie, and Cynthia E. Ogukwe. "Corrosion Inhibition of Mild Steel in 0.5 M H2SO4 Using Ethanol Extract of Funtumia elastica." International Letters of Chemistry, Physics and Astronomy 68 (July 2016): 24–38. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.68.24.
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The adsorption and corrosion inhibitive effect of the ethanol extract ofFuntumia elastica(FE) leaves on mild steel corrosion in 0.5 M H2SO4was studied using gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopic techniques. As well as Fourier transform infrared spectroscopy and computational methods. The gravimetric and electrochemical studies revealed that FE is an adsorption inhibitor. The potentiodynamic polarization result showed that the inhibitor is a mixed type corrosion inhibitor for mild steel in 0.5 M H2SO4, inhibiting both the cathodic and anodic partial reactions. Density functional theory calculations were performed to model the electronic structures of some selected extract constituents (conessine, and ascorbic acid) to confirm their inhibiting potential and established their individual contributions to the observed inhibiting effects.
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Lanotte, A. S., R. Corrado, G. Lacorata, L. Palatella, C. Pizzigalli, I. Schipa, and R. Santoleri. "The role of vertical shear on the horizontal oceanic dispersion." Ocean Science Discussions 12, no. 5 (September 2, 2015): 2073–96. http://dx.doi.org/10.5194/osd-12-2073-2015.
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Abstract. The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of South Mediterranean is investigated by means of observative and model data. In-situ current measurements reveal that vertical velocity gradients in the upper mixed layer decorrelate quite fast (∼ 1 day), whereas basin-scale ocean circulation models tend to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion simulated by an eddy-permitting ocean model, like, e.g., the Mediterranean Forecasting System, is mosty affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out; (2) poorly resolved time variability of vertical velocity profiles in the upper layer. For the case study we have analysed, we show that a suitable use of kinematic parameterisations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications.
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Bouchard, Thomas, Amna Klich, Rene Leiva, Cecilia Pyper, Christophe Genolini, Fabien Subtil, Jean Iwaz, René Ecochard, and Saman Abdullah. "A Quadriparametric Model to Describe the Diversity of Waves Applied to Hormonal Data." Methods of Information in Medicine 57, no. 03 (May 2018): 101–10. http://dx.doi.org/10.3414/me17-01-0102.
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Summary Background: Even in normally cycling women, hormone level shapes may widely vary between cycles and between women. Over decades, finding ways to characterize and compare cycle hormone waves was difficult and most solutions, in particular polynomials or splines, do not correspond to physiologically meaningful parameters. Objective: We present an original concept to characterize most hormone waves with only two parameters. Methods: The modelling attempt considered pregnanediol-3-alpha-glucuronide (PDG) and luteinising hormone (LH) levels in 266 cycles (with ultrasound-identified ovulation day) in 99 normally fertile women aged 18 to 45. The study searched for a convenient wave description process and carried out an extended search for the best fitting density distribution. Results: The highly flexible beta-binomial distribution offered the best fit of most hormone waves and required only two readily available and understandable wave parameters: location and scale. In bell-shaped waves (e.g., PDG curves), early peaks may be fitted with a low location parameter and a low scale parameter; plateau shapes are obtained with higher scale parameters. I-shaped, J-shaped, and U-shaped waves (sometimes the shapes of LH curves) may be fitted with high scale parameter and, respectively, low, high, and medium location parameter. These location and scale parameters will be later correlated with feminine physiological events. Conclusion: Our results demonstrate that, with unimodal waves, complex methods (e.g., functional mixed effects models using smoothing splines, second-order growth mixture models, or functional principal-component- based methods) may be avoided. The use, application, and, especially, result interpretation of four-parameter analyses might be advantageous within the context of feminine physiological events.
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Iehisa, Ikko, Kazuno Negishi, Masahiko Ayaki, and Kazuo Tsubota. "Kinetic visual acuity is correlated with functional visual acuity at higher speeds." BMJ Open Ophthalmology 4, no. 1 (November 2019): e000383. http://dx.doi.org/10.1136/bmjophth-2019-000383.
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ObjectiveTo measure the kinetic visual acuity (KVA) which is the ability to identify approaching objects and the functional visual acuity (FVA) which is continuous VA during 1 min under binocular and monocular condition (non-dominant eye shielding) for healthy subjects, and related ocular parameters to explore their correlation and implication in aspect of integrated visual function.MethodsThe mean age of the 28 participants was 38.6±8.9 years (range, 23–57 years; 6 women). A KVA metre (AS-4Fα) and FVA metre (AS-28) were used to measure KVA and FVA, respectively. Multiple regression analysis was conducted to explore correlations among the measured visual function and related parameters, including age, binocularity, best-corrected visual acuity, refraction and tear break-up time.ResultsThe results of binocular KVA were better than monocular KVA at all speeds. A strong correlation was found between monocular and binocular KVA. The results of binocular FVA were better than monocular FVA (p<0.001) and there was a correlation between monocular and binocular FVA (R=0.638, p<0.001), as well as the maintenance rate for FVA (R=0.228, p=0.003). A linear mixed-effects model revealed that binocularity for KVA prediction was significant at all speeds and FVA was also significant at 60 km/h (p<0.05).ConclusionThe current results suggest that both binocularity and FVA may contribute to KVA.Trial registration numberUMIN00032385
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Peterson, Hope, Rhiannon E. Mayhugh, Mohsen Bahrami, Walter Jack Rejeski, Sean L. Simpson, Keri Heilman, Steven W. Porges, and Paul J. Laurienti. "Influence of Heart Rate Variability on Abstinence-Related Changes in Brain State in Everyday Drinkers." Brain Sciences 11, no. 6 (June 20, 2021): 817. http://dx.doi.org/10.3390/brainsci11060817.
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Alcohol consumption is now common practice worldwide, and functional brain networks are beginning to reveal the complex interactions observed with alcohol consumption and abstinence. The autonomic nervous system (ANS) has a well-documented relationship with alcohol use, and a growing body of research is finding links between the ANS and functional brain networks. This study recruited everyday drinkers in an effort to uncover the relationship between alcohol abstinence, ANS function, and whole brain functional brain networks. Participants (n = 29), 24–60 years-of-age, consumed moderate levels of alcohol regularly (males 2.4 (±0.26) drinks/day, females 2.3 (±0.96) drinks/day). ANS function, specifically cardiac vagal tone, was assessed using the Porges-Bohrer method for calculating respiratory sinus arrhythmia (PBRSA). Functional brain networks were generated from resting-state MRI scans obtained following 3-day periods of typical consumption and abstinence. A multi-task mixed-effects regression model determined the influences of HRV and drinking state on functional network connectivity. Results showed differences in the relationship between the strength of network connections and clustering coefficients across drinking states, moderated by PBRSA. Increases in connection strength between highly clustered nodes during abstinence as PBRSA increases demonstrates a greater possible range of topological configurations at high PBRSA values. This novel finding begins to shed light on the complex interactions between typical alcohol abstinence and physiological responses of the central and autonomic nervous system.