A registered report of a two-site study of variations of the flanker task: ERN experimental effects and data quality.

Error-related negativity is a widely used measure of error monitoring, and many projects are independently moving ERN recorded during a flanker task toward standardization, optimization, and eventual clinical application. However, each project uses a different version of the flanker task and tacitly assumes ERN is functionally equivalent across each version. The routine neglect of a rigorous test of this assumption undermines efforts to integrate ERN findings across tasks, optimize and standardize ERN assessment, and widely apply ERN in clinical trials. The purpose of this registered report was to determine whether ERN shows similar experimental effects (correct vs. error trials) and data quality (intraindividual variability) during three commonly used versions of a flanker task. ERN was recorded from 172 participants during three versions of a flanker task across two study sites. ERN scores showed numerical differences between tasks, raising questions about the comparability of ERN findings across studies and tasks. Although ERN scores from all three versions of the flanker task yielded high data quality and internal consistency, one version did outperform the other two in terms of the size of experimental effects and the data quality. Exploratory analyses of the error positivity (Pe) provided tentative support for the other two versions of the task over the paradigm that appeared optimal for ERN. The present study provides a roadmap for how to statistically compare psychometric characteristics of ERP scores across paradigms and gives preliminary recommendations for flanker tasks to use for ERN- and Pe-focused studies.

Investigating cognitive and motivational proximal outcomes in a randomized clinical trial of writing about the future self to reduce drinking.

BACKGROUND: Drinking identity (the extent to which one links the self with drinking alcohol) is a unique risk factor for college students' hazardous drinking that is not directly targeted by existing interventions. We conducted a study that aimed to decrease drinking identity among college students with hazardous drinking. We adapted a writing task about the future self and tested whether three writing sessions could decrease drinking identity and change drinking. We also investigated whether two additional factors (writing perspective and inclusion of participants' social networks) would enhance task impact. The present study evaluated whether posited proximal cognitive and motivational outcomes (drinking identity, self-efficacy, readiness to change, and drinking intentions) changed immediately after each writing session. METHOD: The study is a randomized clinical trial in which hypotheses and analyses were pre-registered. Participants were 328 college students who met hazardous drinking criteria. The study had a 2 (narrative writing topic: low-risk drinker vs. reduced smartphone use) × 2 (writing perspective: first-person vs. non-first-person) × 2 (social network instruction: instructed to include vs. not) factorial design. Proximal outcomes were drinking identity, self-efficacy, readiness to change, and drinking intentions. The clinical outcome was alcohol consumption. Participants completed three laboratory sessions at weekly intervals that included the writing task and pre- and post-task assessments. RESULTS: Results were largely null, except that readiness to reduce drinking was higher in the low-risk drinker condition and increased over the lab sessions. Time effects indicated that reductions in drinking identity, drinking intentions, and alcohol consumption, and increases in self-efficacy were observed but did not change above and beyond control conditions. CONCLUSIONS: Findings indicate the need to strengthen the writing task and select a more appropriate control task to target proposed proximal outcomes. Future studies might try personalizing the task, evaluating its efficacy with individuals motivated to change their drinking, and using a control task that does not involve imagining a future self.

Is informal practice associated with outcomes in loving-kindness and compassion training? Evidence from pre-post and daily diary assessments.

We investigated whether informal meditation practice (i.e., self-reported application of meditative techniques outside a period of formal meditation) was associated with outcomes in smartphone-based loving-kindness and compassion training. Meditation-naïve participants (n = 351) with clinically elevated symptoms completed measures of psychological distress, loneliness, empathy, and prosociality at baseline and following a two-week intervention. Informal practice, psychological distress, and loneliness were also assessed daily. Steeper increases in informal practice had small associations with pre-post improvements in distress (r = -.18, p = .008) and loneliness (r = -.19, p = .009) but not empathy or prosociality. Using a currently recommended approach for establishing cross-lagged effects in longitudinal data (latent curve model with structured residuals), higher current-day informal practice was associated with decreased next-day distress with a very small effect size (ßs = -.06 to -.04, p = .018) but not decreased next-day loneliness. No cross-lagged associations emerged from distress or loneliness to informal practice. Findings suggest that further investigation into a potential causal role of informal practice is warranted. Future studies experimentally manipulating informal practice are needed.

Quantifying collective motion patterns in mesenchymal cell populations using topological data analysis and agent-based modeling.

Fibroblasts in a confluent monolayer are known to adopt elongated morphologies in which cells are oriented parallel to their neighbors. We collected and analyzed new microscopy movies to show that confluent fibroblasts are motile and that neighboring cells often move in anti-parallel directions in a collective motion phenomenon we refer to as "fluidization" of the cell population. We used machine learning to perform cell tracking for each movie and then leveraged topological data analysis (TDA) to show that time-varying point-clouds generated by the tracks contain significant topological information content that is driven by fluidization, i.e., the anti-parallel movement of individual neighboring cells and neighboring groups of cells over long distances. We then utilized the TDA summaries extracted from each movie to perform Bayesian parameter estimation for the D'Orsgona model, an agent-based model (ABM) known to produce a wide array of different patterns, including patterns that are qualitatively similar to fluidization. Although the D'Orsgona ABM is a phenomenological model that only describes inter-cellular attraction and repulsion, the estimated region of D'Orsogna model parameter space was consistent across all movies, suggesting that a specific level of inter-cellular repulsion force at close range may be a mechanism that helps drive fluidization patterns in confluent mesenchymal cell populations.

The selection of statistical models for reporting count outcomes and intervention effects in brief alcohol intervention trials: A review and recommendations.

Understanding the efficacy and relative effectiveness of a brief alcohol intervention (BAI) relies on obtaining a credible intervention effect estimate. Outcomes in BAI trials are often count variables, such as the number of drinks consumed, which may be overdispersed (i.e., greater variability than expected based on a given model) and zero-inflated (i.e., greater probability of zeros than expected based on a given model). Ignoring such distribution characteristics can lead to biased estimates and invalid statistical conclusions. In this critical review, we identified and reviewed 64 articles that reported count outcomes from a systematic review of BAI trials for adolescents and young adults from 2013 to 2018. Given many statistical models to choose from when analyzing count outcomes, we reviewed the models used and reporting practices in the BAI trial literature. A majority (61.3%) of analyses with count outcomes used linear models despite violations of normality assumptions; 75.6% of outcome variables demonstrated clear overdispersion. We provide an overview of available count models (Poisson, negative binomial, zero-inflated or hurdle, and marginalized zero-inflated Poisson regression) and formulate practical guidelines for reporting outcomes of BAIs. We provide a visual step-by-step decision guide for selecting appropriate statistical models and reporting results for count outcomes. We list accessible resources to help researchers select an appropriate model with which to analyze their data. Recent advances in count distribution-based models hold promise for evaluating count outcomes to gauge the efficacy and effectiveness of BAIs and identify critical covariates in alcohol epidemiologic research. We recommend that researchers report the distributional properties of count outcomes, such as the proportion of zero counts, and select an appropriate statistical analysis for count outcomes using the provided decision tree. By following these recommendations, future research may yield more accurate, transparent, and reproducible results.

Writing about the future self to shift drinking identity: An experimental investigation.

College student drinking is prevalent and costly to public and personal health, leading to calls to identify and target novel mechanisms of behavior change. We aimed to manipulate drinking identity (a cognitive risk factor for hazardous drinking) via three sessions of narrative writing about a future self. We tested whether writing could shift drinking identity and would be accompanied by changes in alcohol consumption and problems. Participants were college students meeting hazardous drinking criteria (N = 328; Mage = 20.15; 59% women, 40% men, 1% gender-diverse; 60% white; 23% Asian; 12% multiple races; 2% other racial groups; 8% identified as Hispanic/Latino/a/x). The study had a 2 [narrative writing topic: low-risk drinker vs. reduced smartphone use] × 2 [writing perspective: first person vs. non-first-person] × 2 [social network instruction: instructed to include vs. not] factorial design. Outcomes were drinking identity, drinking refusal self-efficacy, alcohol consumption, alcohol-related problems, and craving. Participants completed three writing sessions and online follow-up assessments at 2, 4, and 12 weeks. The study is a registered clinical trial; hypotheses and analyses were preregistered (https://osf.io/vy2ep/). Contrary to predictions, narrative writing about a future self as a low-risk drinker did not significantly impact outcomes. Null results extended to expected interactions with writing perspective and social network instructions. The narrative writing task did not shift drinking or alcohol-related outcomes. Future experimental work may benefit from greater flexibility in conceptualizing a future self, recruiting individuals interested in behavior change, and more sensitive measures of drinking identity.

Registered replication report of the construct validity of the error-related negativity (ERN): A multi-site study of task-specific ERN correlations with internalizing and externalizing symptoms.

Intact cognitive control is critical for goal-directed behavior and is widely studied using the error-related negativity (ERN). A common assumption in such studies is that ERNs recorded during different experimental paradigms reflect the same construct or functionally equivalent processes and that ERN is functionally distinct from other error-monitoring event-related brain potentials (ERPs; error positivity [Pe]), other neurophysiological indices of cognitive control (N2), and even other theoretically unrelated indices (visual N1). The present registered report represents a replication-plus-extension study of the psychometric validity of cognitive control ERPs and evaluated the convergent and divergent validity of ERN, Pe, N2, and visual N1 recorded during flanker, Stroop, and Go/no-go tasks. Data from 182 participants were collected from two study sites, and ERP psychometric reliability and validity were evaluated. Findings supported replication of convergent and divergent validity of ERN, Pe, and ΔPe (error minus correct)-these ERPs correlated more with themselves across tasks than with other ERPs measured during the same task. Convergent validity of ΔERN across tasks was not replicated, despite high internal consistency. ERN strongly correlated with N2 at levels similar or higher than those in support of convergent validity for other ERPs, and the present study failed to provide evidence of divergent validity for ERN and Pe from N2 or N1. ERN and ΔERN were unrelated to internalizing or externalizing symptoms. Findings underscore the importance of considering the psychometric validity of ERPs, as it provides a foundation for interpreting and comparing ERPs across tasks and studies.

A systematic review of heart rate variability (HRV) biofeedback treatment following traumatic brain injury (TBI).

OBJECTIVE: Autonomic nervous system dysregulation is a common consequence of traumatic brain injury (TBI). Heart rate variability (HRV) is a cost-effective measure of autonomic nervous system functioning, with studies suggesting decreased HRV following moderate-to-severe TBI. HRV biofeedback treatment may improve post-TBI autonomic nervous system functioning and post-injury emotional and cognitive functioning. We provide a systematic evidence-based review of the state of the literature and effectiveness of HRV biofeedback following TBI. METHOD: We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two coders coded each article and provided quality ratings. Seven papers met inclusion criteria. All studies included a measure of emotional functioning and 5 studies (63%) included neuropsychological outcomes. RESULTS: Participants completed 11 sessions of HRV biofeedback on average (range = 1 to 40). HRV biofeedback was associated with improved HRV following TBI. There was a positive relationship between increased HRV and TBI recovery following biofeedback, including improvements in cognitive and emotional functioning, and physical symptoms such as headaches, dizziness, and sleep problems. CONCLUSION: The literature on HRV biofeedback for TBI is promising, but in its infancy; effectiveness is unclear due to poor-to-fair study quality, and potential publication bias (all studies reported positive results).

Semi-autonomous wound invasion via matrix-deposited, haptotactic cues.

Proper wound healing relies on invasion of fibroblasts via directed migration. While the related experimental and mathematical modeling literature has mainly focused on cell migration directed by soluble cues (chemotaxis), there is ample evidence that fibroblast migration is also directed by insoluble, matrix-bound cues (haptotaxis). Furthermore, numerous studies indicate that fibronectin (FN), a haptotactic ligand for fibroblasts, is present and dynamic in the provisional matrix throughout the proliferative phase of wound healing. In the present work, we show the plausibility of a hypothesis that fibroblasts themselves form and maintain haptotactic gradients in a semi-autonomous fashion. As a precursor to this, we examine the positive control scenario where FN is pre-deposited in the wound matrix, and fibroblasts maintain haptotaxis by removing FN at an appropriate rate. After developing conceptual and quantitative understanding of this scenario, we consider two cases in which fibroblasts activate the latent form of a matrix-loaded cytokine, TGFß, which upregulates the fibroblasts' own secretion of FN. In the first of these, the latent cytokine is pre-patterned and released by the fibroblasts. In the second, fibroblasts in the wound produce the latent TGFß, with the presence of the wound providing the only instruction. In all cases, wound invasion is more effective than a negative control model with haptotaxis disabled; however, there is a trade-off between the degree of fibroblast autonomy and the rate of invasion.

Maturing Out: Between- and Within-Persons Changes in Social-Network Drinking, Drinking Identity, and Hazardous Drinking Following College Graduation.

Many college students reduce hazardous drinking (HD) following graduation without treatment. Identifying cognitive mechanisms facilitating this "natural" reduction in HD during this transition is crucial. We evaluated drinking identity as a potential mechanism and tested whether within-person changes in one's social network's drinking were linked to within-person changes in drinking identity and subsequent within-person changes in HD. A sample of 422 undergraduates reporting HD was followed from six months before until two years after graduation. Their drinking, drinking identity, and social networks were assessed online. Within-person changes in drinking identity did not mediate the relationship between within-person changes in social network drinking and personal HD, though significant positive between-person associations among all constructs were found. Instead, there was some evidence that within-person changes in drinking identity followed changes in HD, suggesting that drinking identity may function as a marker versus mechanism of "natural" HD reduction during transition out of college.

Which is Better for Individual Participant Data Meta-Analysis of Zero-Inflated Count Outcomes, One-Step or Two-Step Analysis? A Simulation Study.

Meta-analysis using individual participant data (IPD) is an important methodology in intervention research because it (a) increases accuracy and precision of estimates, (b) allows researchers to investigate mediators and moderators of treatment effects, and (c) makes use of extant data. IPD meta-analysis can be conducted either via a one-step approach that uses data from all studies simultaneously, or a two-step approach, which aggregates data for each study and then combines them in a traditional meta-analysis model. Unfortunately, there are no evidence-based guidelines for how best to approach IPD meta-analysis for count outcomes with many zeroes, such as alcohol use. We used simulation to compare the performance of four hurdle models (3 one-step and 1 two-step models) for zero-inflated count IPD, under realistic data conditions. Overall, all models yielded adequate coverage and bias for the treatment effect in the count portion of the model, across all data conditions. However, in the zero portion, the treatment effect was underestimated in most models and data conditions, especially when there were fewer studies. The performance of both one- and two-step approaches depended on the formulation of the treatment effects, suggesting a need to carefully consider model assumptions and specifications when using IPD.

Genetic Variants Associated With Systolic Blood Pressure in Children and Adolescents.

Background Genetics, along with lifestyle and behavioral characteristics, play an important role in hypertension in adults. Our aim was to identify genetic variants associated with blood pressure in childhood and adolescence. Methods and Results We conducted a candidate single-nucleotide polymorphism (SNP) analysis and genome-wide association study among 9778 participants aged <18 years in BioVU, the Vanderbilt University Medical Center biobank. The outcome was childhood blood pressure percentile from age 0 to 18 years. For the candidate SNP analysis, a total of 457 previously identified SNPs were examined. Linear regression was used to test the association between genetic variants and median systolic blood pressure (SBP) percentile. Adjusted models included median age, self-reported sex, race, the first 4 principal components of ancestry, and median body mass index Z score. Analyses were conducted in the overall cohort and stratified by age group. A polygenic risk score was calculated for each participant, and the association between polygenic risk score and median SBP percentile in childhood was examined using linear regression. In the overall candidate SNP analysis, 2 SNPs reached significance: rs1018148 (FBN1; P=1.0×10-4) and rs11105354 (ATP2B1; P=1.4×10-4). In the postpuberty age group, 1 SNP reached significance: rs1018148 (FBN1; P=2.2×10-5). In the genome-wide association study of all participants, no SNPs reached genome-wide significance. Higher polygenic risk score was associated with higher SBP percentile (ß, 0.35 [95% CI, 0.10-0.60)], and there was a significant interaction with age (P for interaction<0.01). Conclusions These findings suggest that genetic variants play an important role in SBP in childhood and adolescence and provide evidence for age-specific genetic associations with SBP.

Disentangling the within- and between-person aspects of implicit alcohol associations on hazardous drinking.

Indirect measures have been used to assess the strength of automatically activated, alcohol-related associations and their relation to hazardous drinking. However, little is known about the longitudinal contributions of between-person and within-person components of implicit alcohol associations (IAAs) to college students' hazardous drinking over time. This study examined how within- and between-person variability in three measures of IAA (drinking identity, alcohol approach, and alcohol excite) are related to hazardous drinking while controlling for their explicit, self-report counterparts. First- and second-year U.S. college students (N = 506; 57% female) completed web-based assessments once every 3 months up to eight assessments, which included IAA measures (Implicit Association Tests), explicit counterparts of the IAAs, and self-reported hazardous drinking (alcohol consumption, problems, and risk of alcohol use disorder). Bayesian generalized multilevel models were used to examine between- and within-person associations among IAA, their explicit counterparts, and hazardous drinking. Results showed that between persons, mean levels of all three IAAs were positively associated with hazardous drinking over time. Once their explicit, self-report counterparts were included, however, only drinking identity IAA remained significant. Within persons, increases in drinking identity IAA were associated with increases in subsequent hazardous drinking risk, even after controlling for its explicit counterpart. These results suggest the importance of disentangling and simultaneously investigating between- and within-person processes in IAAs. Although the between-person component of IAAs may play a larger role in the prediction of hazardous drinking, examining the within-person component of IAA, at least for drinking identity, also appears to be important. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Resilience risk controls and the Netflix Unified Resilience Framework.

This paper argues that programmes built around existing enterprise resilience/business continuity management (ER/BCM) metrics provide a low return on investment, which ultimately can damage the perceived value of the industry. It goes on to introduce a new approach to creating and measuring ER/BCM programmes that provides a much greater level of return for a smaller investment. Finally, it describes how this new approach can be used to satisfy traditional programme requirements, and provides a shared framework for emerging uses, such as cyber resilience.

Alliance With an Unguided Smartphone App: Validation of the Digital Working Alliance Inventory.

The working alliance may be relevant in unguided smartphone-based interventions, but no validated measure exists. We evaluated the psychometric properties of the six-item Digital Working Alliance Inventory (DWAI) using a cross-sectional survey of meditation app users (n = 290) and the intervention arm of a randomized trial testing a smartphone-based meditation app (n = 314). Exploratory factor analysis suggested a single-factor solution which was replicated using longitudinal confirmatory factor analysis. The DWAI showed adequate internal consistency and test-retest reliability. Discriminant validity was supported by a lack of association with social desirability, psychological distress, and preference for a waitlist condition. Convergent validity was supported by positive associations with perceived app effectiveness and preference for an app condition. Supporting predictive validity, DWAI scores positively predicted self-reported and objective app utilization. When assessed at Weeks 3 or 4 of the intervention, but not earlier, DWAI scores predicted pre-post reductions in psychological distress.

Understanding the Error in Psychopathology: Notable Intraindividual Differences in Neural Variability of Performance Monitoring.

BACKGROUND: Abnormal performance monitoring is a possible transdiagnostic marker of psychopathology. Research on neural indices of performance monitoring, including the error-related negativity (ERN), typically examines group and interindividual (between-person) differences in mean/average scores. Intraindividual (within-person) variability in activity captures the capacity to dynamically adjust from moment to moment, and excessive variability appears maladaptive. Intraindividual variability in ERN represents a unique and largely unexamined dimension that might impact functioning. We tested whether psychopathology group differences (major depressive disorder, generalized anxiety disorder, obsessive-compulsive disorder) or corresponding psychiatric symptoms account for intraindividual variability in single-trial ERN scores. METHODS: High-density electroencephalogram was recorded during a semantic flanker task in 51 participants with major depressive disorder, 44 participants with generalized anxiety disorder, 31 participants with obsessive-compulsive disorder, and 56 psychiatrically healthy participants. Time-window mean ERN amplitude was scored 0-125 ms following participant response across four frontocentral sites. Multilevel location-scale models were used to simultaneously examine interindividual and intraindividual differences in ERN. RESULTS: Analyses indicated considerable intraindividual variability in ERN that was common across groups. However, we did not find strong evidence to support relationships between ERN and psychopathology groups or transdiagnostic symptoms. CONCLUSIONS: These findings point to important methodological implications for studies of performance monitoring in healthy and clinical populations-the common assumption of fixed intraindividual variability (i.e., residual variance) may be inappropriate for ERN studies. Implementation of multilevel location-scale models in future research can leverage between-person differences in intraindividual variability in performance monitoring to gain a rich understanding of trial-to-trial performance monitoring dynamics.

A Structural Equation Modeling Approach to Meta-analytic Mediation Analysis Using Individual Participant Data: Testing Protective Behavioral Strategies as a Mediator of Brief Motivational Intervention Effects on Alcohol-Related Problems.

This paper introduces a meta-analytic mediation analysis approach for individual participant data (IPD) from multiple studies. Mediation analysis evaluates whether the effectiveness of an intervention on health outcomes occurs because of change in a key behavior targeted by the intervention. However, individual trials are often statistically underpowered to test mediation hypotheses. Existing approaches for evaluating mediation in the meta-analytic context are limited by their reliance on aggregate data; thus, findings may be confounded with study-level differences unrelated to the pathway of interest. To overcome the limitations of existing meta-analytic mediation approaches, we used a one-stage estimation approach using structural equation modeling (SEM) to combine IPD from multiple studies for mediation analysis. This approach (1) accounts for the clustering of participants within studies, (2) accommodates missing data via multiple imputation, and (3) allows valid inferences about the indirect (i.e., mediated) effects via bootstrapped confidence intervals. We used data (N = 3691 from 10 studies) from Project INTEGRATE (Mun et al. Psychology of Addictive Behaviors, 29, 34-48, 2015) to illustrate the SEM approach to meta-analytic mediation analysis by testing whether improvements in the use of protective behavioral strategies mediate the effectiveness of brief motivational interventions for alcohol-related problems among college students. To facilitate the application of the methodology, we provide annotated computer code in R and data for replication. At a substantive level, stand-alone personalized feedback interventions reduced alcohol-related problems via greater use of protective behavioral strategies; however, the net-mediated effect across strategies was small in size, on average.

The data-processing multiverse of event-related potentials (ERPs): A roadmap for the optimization and standardization of ERP processing and reduction pipelines.

In studies of event-related brain potentials (ERPs), numerous decisions about data processing are required to extract ERP scores from continuous data. Unfortunately, the systematic impact of these choices on the data quality and psychometric reliability of ERP scores or even ERP scores themselves is virtually unknown, which is a barrier to the standardization of ERPs. The aim of the present study was to optimize processing pipelines for the error-related negativity (ERN) and error positivity (Pe) by considering a multiverse of data processing choices. A multiverse analysis of a data processing pipeline examines the impact of a large set of different reasonable choices to determine the robustness of effects, such as the impact of different decisions on between-trial standard deviations (i.e., data quality) and between-condition differences (i.e., experimental effects). ERN and Pe data from 298 healthy young adults were used to determine the impact of different methodological choices on data quality and experimental effects (correct vs. error trials) at several key stages: highpass filtering, lowpass filtering, ocular artifact correction, reference, baseline adjustment, scoring sensors, and measurement procedure. This multiverse analysis yielded 3,456 ERN scores and 576 Pe scores per person. An optimized pipeline for ERN included a 15 Hz lowpass filter, ICA-based ocular artifact correction, and a region of interest (ROI) approach to scoring. For Pe, the optimized pipeline included a 0.10 Hz highpass filter, 30 Hz lowpass filter, regression-based ocular artifact correction, a -200 to 0 ms baseline adjustment window, and an ROI approach to scoring. The multiverse approach can be used to optimize pipelines for eventual standardization, which would support efforts toward establishing normative ERP databases. The proposed process of analyzing the data-processing multiverse of ERP scores paves the way for better refinement, identification, and selection of data processing parameters, ultimately improving the precision and utility of ERPs.

Microfluidic devices fitted with "flowver" paper pumps generate steady, tunable gradients for extended observation of chemotactic cell migration.

Microfluidics approaches have gained popularity in the field of directed cell migration, enabling control of the extracellular environment and integration with live-cell microscopy; however, technical hurdles remain. Among the challenges are the stability and predictability of the environment, which are especially critical for the observation of fibroblasts and other slow-moving cells. Such experiments require several hours and are typically plagued by the introduction of bubbles and other disturbances that naturally arise in standard microfluidics protocols. Here, we report on the development of a passive pumping strategy, driven by the high capillary pressure and evaporative capacity of paper, and its application to study fibroblast chemotaxis. The paper pumps-flowvers (flow + clover)-are inexpensive, compact, and scalable, and they allow nearly bubble-free operation, with a predictable volumetric flow rate on the order of µl/min, for several hours. To demonstrate the utility of this approach, we combined the flowver pumping strategy with a Y-junction microfluidic device to generate a chemoattractant gradient landscape that is both stable (6+ h) and predictable (by finite-element modeling calculations). Integrated with fluorescence microscopy, we were able to recapitulate previous, live-cell imaging studies of fibroblast chemotaxis to platelet derived growth factor (PDGF), with an order-of-magnitude gain in throughput. The increased throughput of single-cell analysis allowed us to more precisely define PDGF gradient conditions conducive for chemotaxis; we were also able to interpret how the orientation of signaling through the phosphoinositide 3-kinase pathway affects the cells' sensing of and response to conducive gradients.

The open access advantage for studies of human electrophysiology: Impact on citations and Altmetrics.

Barriers to accessing scientific findings contribute to knowledge inequalities based on financial resources and decrease the transparency and rigor of scientific research. Recent initiatives aim to improve access to research as well as methodological rigor via transparency and openness. We sought to determine the impact of such initiatives on open access publishing in the sub-area of human electrophysiology and the impact of open access on the attention articles received in the scholarly literature and other outlets. Data for 35,144 articles across 967 journals from the last 20 years were examined. Approximately 35% of articles were open access, and the rate of publication of open-access articles increased over time. Open access articles showed 9 to 21% more PubMed and CrossRef citations and 39% more Altmetric mentions than closed access articles. Green open access articles (i.e., author archived) did not differ from non-green open access articles (i.e., publisher archived) with respect to citations and were related to higher Altmetric mentions. These findings demonstrate that open-access publishing is increasing in popularity in the sub-area of human electrophysiology and that open-access articles enjoy the "open access advantage" in citations similar to the larger scientific literature. The benefit of the open access advantage may motivate researchers to make their publications open access and pursue publication outlets that support it. In consideration of the direct connection between citations and journal impact factor, journal editors may improve the accessibility and impact of published articles by encouraging authors to self-archive manuscripts on preprint servers.