Erich Greene | Yale University (original) (raw)

Papers by Erich Greene

Cost Effectiveness and Resource Allocation, Aug 2, 2023

Objectives The Strategies to Reduce Injuries and Develop Confidence in Elders (STRIDE) Study clus... more Objectives The Strategies to Reduce Injuries and Develop Confidence in Elders (STRIDE) Study cluster-randomized 86 primary care practices in 10 healthcare systems to a patient-centered multifactorial fall injury prevention intervention or enhanced usual care, enrolling 5451 participants. We estimated total healthcare costs from participant-reported fall injuries receiving medical attention (FIMA) that were averted by the STRIDE intervention and tested for healthcaresystem-level heterogeneity and heterogeneity of treatment effect (HTE). Methods Participants were community-dwelling adults age ≥ 70 at increased fall injury risk. We estimated practicelevel total costs per person-year of follow-up (PYF), assigning unit costs to FIMA with and without an overnight hospital stay. Using independent variables for treatment arm, healthcare system, and their interaction, we fit a generalized linear model with log link, log follow-up time offset, and Tweedie error distribution.

Statistical Methods in Medical Research, Nov 22, 2022

Simulation studies play an important role in evaluating the performance of statistical models dev... more Simulation studies play an important role in evaluating the performance of statistical models developed for analyzing complex survival data such as those with competing risks and clustering. This article aims to provide researchers with a basic understanding of competing risks data generation, techniques for inducing cluster-level correlation, and ways to combine them together in simulation studies, in the context of randomized clinical trials with a binary exposure or treatment. We review data generation with competing and semi-competing risks and three approaches of inducing cluster-level correlation for time-to-event data: the frailty model framework, the probability transform, and Moran’s algorithm. Using exponentially distributed event times as an example, we discuss how to introduce cluster-level correlation into generating complex survival outcomes, and illustrate multiple ways of combining these methods to simulate clustered, competing and semi-competing risks data with pre-specified correlation values or degree of clustering.

Journal of the American Geriatrics Society, Aug 6, 2022

Background: Falls are common in older adults and can lead to severe injuries. The Strategies to R... more Background: Falls are common in older adults and can lead to severe injuries. The Strategies to Reduce Injuries and Develop Confidence in Elders (STRIDE) trial cluster-randomized 86 primary care practices across 10 health systems to a multifactorial intervention to prevent fall injuries, delivered by registered nurses trained as falls care managers, or enhanced usual care. STRIDE enrolled 5451 community-dwelling older adults age ≥70 at increased fall injury risk. Methods: We assessed fall-related outcomes via telephone interviews of participants (or proxies) every 4 months. At baseline, 12 and 24 months, we assessed health-related quality of life (HRQOL) using the EQ-5D-5L and EQ-VAS. We used Poisson models to assess intervention effects on falls, fall-related fractures, fall injuries leading to hospital admission, and fall injuries leading to medical attention. We used hierarchical longitudinal linear models to assess HRQOL. Results: For recurrent event models, intervention versus control incidence rate ratios were 0.97 (95% confidence interval [CI], 0.93-1.00; p = 0.048) for falls, 0.93 (95% CI, 0.80-1.08; p = 0.337) for self-reported fractures, 0.89 (95% CI, 0.73-1.07; p = 0.205) for adjudicated fractures, 0.91 (95% CI, 0.77-1.07; p = 0.263) for falls leading to hospital admission, and 0.97 (95% CI, 0.89-1.06; p = 0.477) for falls leading to medical attention. Similar effect sizes (non-For affiliation refer to page 7

medRxiv (Cold Spring Harbor Laboratory), Apr 26, 2023

This paper presents novel datasets providing numerical representations of ICD-10-CM codes by gene... more This paper presents novel datasets providing numerical representations of ICD-10-CM codes by generating description embeddings using a large language model followed by a dimension reduction via autoencoder. The embeddings serve as informative input features for machine learning models by capturing relationships among categories and preserving inherent context information. The model generating the data was validated in two ways. First, the dimension reduction was validated using an autoencoder, and secondly, a supervised model was created to estimate the ICD-10-CM hierarchical categories. Results show that the dimension of the data can be reduced to as few as 10 dimensions while maintaining the ability to reproduce the original embeddings, with the fidelity decreasing as the reduced-dimension representation decreases. Multiple compression levels are provided, allowing users to choose as per their requirements. The readily available datasets of ICD-10-CM codes are anticipated to be highly valuable for researchers in biomedical informatics, enabling more advanced analyses in the field. This approach has the potential to significantly improve the utility of ICD-10-CM codes in the biomedical domain.

Innovation in Aging, Jun 30, 2017

Recent work drawing a clearer distinction between explanatory clinical trials (concerned with the... more Recent work drawing a clearer distinction between explanatory clinical trials (concerned with the estimation of causal effects) and pragmatic trials (focused on selection between therapeutic strategies) illuminates the interplay between internal validity and the generalizability of quantitative results. In gerontology and geriatrics, these tensions present a particular challenge, as there is often a dramatic contrast between those individuals eligible to enroll in intervention trials and the more diverse older patient populations to which conclusions would ideally apply. In practice, large multisite trials are often designed with both explanatory and pragmatic considerations in mind. Therefore, flexible methodologies are required to insure valid design while bolstering the generalizability of results. In this symposium, we provide a series of international perspectives on modern approaches to participant recruitment and retention, randomization, statistical analysis, and research ethics in the context of complex sampling populations and flexible research designs. We focus in particular on scenarios in which clustered sampling of older participants is necessary, either because of the nature of the intervention (e.g. a change in clinical practices) or the population under study (e.g. where patient subgroups are nested within geographic regions). We then consider the ethical implications of enrollment of older subjects in complex trials with pragmatic foci, for which foundational principles may differ from those of conventional explanatory trials. Finally, we discuss a framework guiding the interplay between trial design, best statistical practices, and the ethical conduct of interventional research, and consider the application of these designs to research within differing healthcare systems.

Journal of the American Geriatrics Society, Aug 4, 2022

Background: Evidence-based multifactorial fall prevention interventions in clinical practice have... more Background: Evidence-based multifactorial fall prevention interventions in clinical practice have been less effective than expected. One plausible reason is that older adults' engagement in fall prevention care is suboptimal. Methods: This was a post-hoc analysis of 2403 older adults' engagement in a multifactorial fall prevention intervention in the Strategies to Reduce Injuries and Develop Confidence in Elders (STRIDE) pragmatic trial. Based on the direct clinical care level of the Patient and Family Continuum of Engagement (CE) framework, three indicators of progressively interactive engagement were assessed: (1) Consultation (receiving information), (2) Involvement (prioritizing risks), and (3) Partnership (identifying prevention actions). Drop off at each step was determined as well as predictors of engagement. Results: The participants' engagement waned with increasingly interactive CE domains. Although all participants received information about their positive fall risk factors (consultation) and most (51%-96%) prioritized them (involvement), fewer participants (33%-55%) identified fall prevention actions (partnership) for most of their risk factors, except for strength gait or balance problems (95%). More participants (70%) identified home exercises than other actions. Finally, fall prevention actions were identified more commonly among participants who received two visits compared to one (OR = 2.33 [95% CI, 2.06-2.64]), were ≥80 years old (OR = 1.83 [95% CI, 1.51-2.23]), and had fewer fall risk factors (OR = 0.90 [95% CI, 0.83-0.99]). Conclusions: The drop-off in participants' engagement based on the level of their interaction with clinicians suggests that future multifactorial fall prevention interventions need to be more focused on interactive patient-clinician partnerships that help older adults increase and maintain fall prevention actions. Our analyses suggest that more frequent contact with clinicians and

This paper presents novel datasets providing numerical representations of ICD-10-CM codes by gene... more This paper presents novel datasets providing numerical representations of ICD-10-CM codes by generating description embeddings using a large language model and applying autoencoders for dimensionality reduction. The embeddings serve as informative input features for machine learning models by capturing relationships among categories and preserving inherent information. The model generating the data was validated in two ways. Firstly, the dimension reduction was validated using an autoencoder, and secondly, a supervised model was created to estimate the ICD-10-CM hierarchical categories. Results show that the dimension of the data can be reduced to as few as 10 dimensions while maintaining the ability to reproduce the original embeddings, with the fidelity decreasing as the reduced-dimension representation decreases. Multiple compression levels are provided, allowing users to choose as per their requirements. The readily available datasets of ICD-10-CM codes are anticipated to be hig...

Statistical Methods in Medical Research, 2022

While statistical methods for analyzing cluster randomized trials with continuous and binary outc... more While statistical methods for analyzing cluster randomized trials with continuous and binary outcomes have been extensively studied and compared, little comparative evidence has been provided for analyzing cluster randomized trials with survival outcomes in the presence of competing risks. Motivated by the Strategies to Reduce Injuries and Develop Confidence in Elders trial, we carried out a simulation study to compare the operating characteristics of several existing population-averaged survival models, including the marginal Cox, marginal Fine and Gray, and marginal multi-state models. For each model, we found that adjusting for the intraclass correlations through the sandwich variance estimator effectively maintained the type I error rate when the number of clusters is large. With no more than 30 clusters, however, the sandwich variance estimator can exhibit notable negative bias, and a permutation test provides better control of type I error inflation. Under the alternative, the...

STRIDE Acknowledgements. (DOCX 32 kb)

Rules for Adjudicating. (PDF 266 kb)

STRIDE Adjudication System Instructions. (PDF 539 kb)

Clinical Trials, 2021

Background/Aim In clinical trials, there is potential for bias from unblinded observers that may ... more Background/Aim In clinical trials, there is potential for bias from unblinded observers that may influence ascertainment of outcomes. This issue arose in the Strategies to Reduce Injuries and Develop Confidence in Elders trial, a cluster randomized trial to test a multicomponent intervention versus enhanced usual care (control) to prevent serious fall injuries, originally defined as a fall injury leading to medical attention. An unblinded nurse falls care manager administered the intervention, while the usual care arm did not involve contact with a falls care manager. Thus, there was an opportunity for falls care managers to refer participants reporting falls to seek medical attention. Since this type of observer bias could not occur in the usual care arm, there was potential for additional falls to be reported in the intervention arm, leading to dilution of the intervention effect and a reduction in study power. We describe the clinical basis for ascertainment bias, the statistical...

Innovation in Aging, 2017

for intrarater reliability. The administration time of the tool was 2.6 minutes on average (sd = ... more for intrarater reliability. The administration time of the tool was 2.6 minutes on average (sd = 0.9). Data on predictive validity in a cohort of 2,691 hospitalized older patients will be available soon and reported as well.

Cerebral Cortex, Mar 1, 2003

Cognitive, Affective, & Behavioral Neuroscience, Sep 1, 2005

Institutes of Health (MH 62196). We thank Todd Constable and Rob Fulbright for helpful discussion... more Institutes of Health (MH 62196). We thank Todd Constable and Rob Fulbright for helpful discussions regarding f MRI procedures, Hedy Sarofin for technical assistance in f MRI data collection, and Joe McGuire for assistance in conducting Experiment 6A and in preparing figures. Correspondence relating to this article may be sent to M.

Journal of Cognitive Neuroscience, Apr 1, 2006

& To investigate whether emotional arousal affects memorial feature binding, we had participants ... more & To investigate whether emotional arousal affects memorial feature binding, we had participants complete a short-term source-monitoring task-remembering the locations of four different pictures over a brief delay. On each trial, the four pictures were all either high arousal, medium arousal, or low arousal. Memory for picture-location conjunctions decreased as arousal increased. In addition, source memory for the location of negative pictures was worse among participants with higher depression scores. Two subsequent functional magnetic resonance imaging experiments showed that relative to low-arousal trials, high-and medium-arousal trials resulted in greater activity in areas associated with visual processing (fusiform gyrus, middle temporal gyrus/middle occipital gyrus, lingual gyrus) and less activity in superior precentral gyrus and the precentral-superior temporal intersect. These findings suggest that arousal (and perhaps negative valence for depressed people) recruits attention to items thereby disrupting working memory processes that help bind features together. &

Physical review, Oct 1, 1991

Neuroreport, Oct 2, 2006

We investigated the hypothesis that arousal recruits attention to item information, thereby disru... more We investigated the hypothesis that arousal recruits attention to item information, thereby disrupting working memory processes that help bind items to context. Using functional magnetic resonance imaging, we compared brain activity when participants remembered negative or neutral picture^location conjunctions (source memory) versus pictures only. Behaviorally, negative trials showed disruption of short-term source, but not picture, memory; long-term picture recognition memory was better for negative than for neutral pictures. Activity in areas involved in working memory and feature integration (precentral gyrus and its intersect with superior temporal gyrus) was attenuated on negative compared with neutral source trials relative to picture-only trials. Visual processing areas (middle occipital and lingual gyri) showed greater activity for negative than for neutral trials, especially on picture-only trials.

Recurrent event data are common in clinical studies when participants are followed longitudinally... more Recurrent event data are common in clinical studies when participants are followed longitudinally, and are often subject to a terminal event. With the increasing popularity of large pragmatic trials and a heterogeneous source population, participants are often nested in clinics and can be either susceptible or structurally unsusceptible to the recurrent process. These complications require new modeling strategies to accommodate potential zero-event inflation as well as hierarchical data structures in both the terminal and non-terminal event processes. In this paper, we develop a Bayesian semiparametric model to jointly characterize the zero-inflated recurrent event process and the terminal event process. We use a point mass mixture of non-homogeneous Poisson processes to describe the recurrent intensity and introduce shared random effects from different sources to bridge the non-terminal and terminal event processes. To achieve robustness, we consider nonparametric Dirichlet process...

Cost Effectiveness and Resource Allocation, Aug 2, 2023

Objectives The Strategies to Reduce Injuries and Develop Confidence in Elders (STRIDE) Study clus... more Objectives The Strategies to Reduce Injuries and Develop Confidence in Elders (STRIDE) Study cluster-randomized 86 primary care practices in 10 healthcare systems to a patient-centered multifactorial fall injury prevention intervention or enhanced usual care, enrolling 5451 participants. We estimated total healthcare costs from participant-reported fall injuries receiving medical attention (FIMA) that were averted by the STRIDE intervention and tested for healthcaresystem-level heterogeneity and heterogeneity of treatment effect (HTE). Methods Participants were community-dwelling adults age ≥ 70 at increased fall injury risk. We estimated practicelevel total costs per person-year of follow-up (PYF), assigning unit costs to FIMA with and without an overnight hospital stay. Using independent variables for treatment arm, healthcare system, and their interaction, we fit a generalized linear model with log link, log follow-up time offset, and Tweedie error distribution.

Statistical Methods in Medical Research, Nov 22, 2022

Simulation studies play an important role in evaluating the performance of statistical models dev... more Simulation studies play an important role in evaluating the performance of statistical models developed for analyzing complex survival data such as those with competing risks and clustering. This article aims to provide researchers with a basic understanding of competing risks data generation, techniques for inducing cluster-level correlation, and ways to combine them together in simulation studies, in the context of randomized clinical trials with a binary exposure or treatment. We review data generation with competing and semi-competing risks and three approaches of inducing cluster-level correlation for time-to-event data: the frailty model framework, the probability transform, and Moran’s algorithm. Using exponentially distributed event times as an example, we discuss how to introduce cluster-level correlation into generating complex survival outcomes, and illustrate multiple ways of combining these methods to simulate clustered, competing and semi-competing risks data with pre-specified correlation values or degree of clustering.

Journal of the American Geriatrics Society, Aug 6, 2022

Background: Falls are common in older adults and can lead to severe injuries. The Strategies to R... more Background: Falls are common in older adults and can lead to severe injuries. The Strategies to Reduce Injuries and Develop Confidence in Elders (STRIDE) trial cluster-randomized 86 primary care practices across 10 health systems to a multifactorial intervention to prevent fall injuries, delivered by registered nurses trained as falls care managers, or enhanced usual care. STRIDE enrolled 5451 community-dwelling older adults age ≥70 at increased fall injury risk. Methods: We assessed fall-related outcomes via telephone interviews of participants (or proxies) every 4 months. At baseline, 12 and 24 months, we assessed health-related quality of life (HRQOL) using the EQ-5D-5L and EQ-VAS. We used Poisson models to assess intervention effects on falls, fall-related fractures, fall injuries leading to hospital admission, and fall injuries leading to medical attention. We used hierarchical longitudinal linear models to assess HRQOL. Results: For recurrent event models, intervention versus control incidence rate ratios were 0.97 (95% confidence interval [CI], 0.93-1.00; p = 0.048) for falls, 0.93 (95% CI, 0.80-1.08; p = 0.337) for self-reported fractures, 0.89 (95% CI, 0.73-1.07; p = 0.205) for adjudicated fractures, 0.91 (95% CI, 0.77-1.07; p = 0.263) for falls leading to hospital admission, and 0.97 (95% CI, 0.89-1.06; p = 0.477) for falls leading to medical attention. Similar effect sizes (non-For affiliation refer to page 7

medRxiv (Cold Spring Harbor Laboratory), Apr 26, 2023

This paper presents novel datasets providing numerical representations of ICD-10-CM codes by gene... more This paper presents novel datasets providing numerical representations of ICD-10-CM codes by generating description embeddings using a large language model followed by a dimension reduction via autoencoder. The embeddings serve as informative input features for machine learning models by capturing relationships among categories and preserving inherent context information. The model generating the data was validated in two ways. First, the dimension reduction was validated using an autoencoder, and secondly, a supervised model was created to estimate the ICD-10-CM hierarchical categories. Results show that the dimension of the data can be reduced to as few as 10 dimensions while maintaining the ability to reproduce the original embeddings, with the fidelity decreasing as the reduced-dimension representation decreases. Multiple compression levels are provided, allowing users to choose as per their requirements. The readily available datasets of ICD-10-CM codes are anticipated to be highly valuable for researchers in biomedical informatics, enabling more advanced analyses in the field. This approach has the potential to significantly improve the utility of ICD-10-CM codes in the biomedical domain.

Innovation in Aging, Jun 30, 2017

Recent work drawing a clearer distinction between explanatory clinical trials (concerned with the... more Recent work drawing a clearer distinction between explanatory clinical trials (concerned with the estimation of causal effects) and pragmatic trials (focused on selection between therapeutic strategies) illuminates the interplay between internal validity and the generalizability of quantitative results. In gerontology and geriatrics, these tensions present a particular challenge, as there is often a dramatic contrast between those individuals eligible to enroll in intervention trials and the more diverse older patient populations to which conclusions would ideally apply. In practice, large multisite trials are often designed with both explanatory and pragmatic considerations in mind. Therefore, flexible methodologies are required to insure valid design while bolstering the generalizability of results. In this symposium, we provide a series of international perspectives on modern approaches to participant recruitment and retention, randomization, statistical analysis, and research ethics in the context of complex sampling populations and flexible research designs. We focus in particular on scenarios in which clustered sampling of older participants is necessary, either because of the nature of the intervention (e.g. a change in clinical practices) or the population under study (e.g. where patient subgroups are nested within geographic regions). We then consider the ethical implications of enrollment of older subjects in complex trials with pragmatic foci, for which foundational principles may differ from those of conventional explanatory trials. Finally, we discuss a framework guiding the interplay between trial design, best statistical practices, and the ethical conduct of interventional research, and consider the application of these designs to research within differing healthcare systems.

Journal of the American Geriatrics Society, Aug 4, 2022

Background: Evidence-based multifactorial fall prevention interventions in clinical practice have... more Background: Evidence-based multifactorial fall prevention interventions in clinical practice have been less effective than expected. One plausible reason is that older adults' engagement in fall prevention care is suboptimal. Methods: This was a post-hoc analysis of 2403 older adults' engagement in a multifactorial fall prevention intervention in the Strategies to Reduce Injuries and Develop Confidence in Elders (STRIDE) pragmatic trial. Based on the direct clinical care level of the Patient and Family Continuum of Engagement (CE) framework, three indicators of progressively interactive engagement were assessed: (1) Consultation (receiving information), (2) Involvement (prioritizing risks), and (3) Partnership (identifying prevention actions). Drop off at each step was determined as well as predictors of engagement. Results: The participants' engagement waned with increasingly interactive CE domains. Although all participants received information about their positive fall risk factors (consultation) and most (51%-96%) prioritized them (involvement), fewer participants (33%-55%) identified fall prevention actions (partnership) for most of their risk factors, except for strength gait or balance problems (95%). More participants (70%) identified home exercises than other actions. Finally, fall prevention actions were identified more commonly among participants who received two visits compared to one (OR = 2.33 [95% CI, 2.06-2.64]), were ≥80 years old (OR = 1.83 [95% CI, 1.51-2.23]), and had fewer fall risk factors (OR = 0.90 [95% CI, 0.83-0.99]). Conclusions: The drop-off in participants' engagement based on the level of their interaction with clinicians suggests that future multifactorial fall prevention interventions need to be more focused on interactive patient-clinician partnerships that help older adults increase and maintain fall prevention actions. Our analyses suggest that more frequent contact with clinicians and

This paper presents novel datasets providing numerical representations of ICD-10-CM codes by gene... more This paper presents novel datasets providing numerical representations of ICD-10-CM codes by generating description embeddings using a large language model and applying autoencoders for dimensionality reduction. The embeddings serve as informative input features for machine learning models by capturing relationships among categories and preserving inherent information. The model generating the data was validated in two ways. Firstly, the dimension reduction was validated using an autoencoder, and secondly, a supervised model was created to estimate the ICD-10-CM hierarchical categories. Results show that the dimension of the data can be reduced to as few as 10 dimensions while maintaining the ability to reproduce the original embeddings, with the fidelity decreasing as the reduced-dimension representation decreases. Multiple compression levels are provided, allowing users to choose as per their requirements. The readily available datasets of ICD-10-CM codes are anticipated to be hig...

Statistical Methods in Medical Research, 2022

While statistical methods for analyzing cluster randomized trials with continuous and binary outc... more While statistical methods for analyzing cluster randomized trials with continuous and binary outcomes have been extensively studied and compared, little comparative evidence has been provided for analyzing cluster randomized trials with survival outcomes in the presence of competing risks. Motivated by the Strategies to Reduce Injuries and Develop Confidence in Elders trial, we carried out a simulation study to compare the operating characteristics of several existing population-averaged survival models, including the marginal Cox, marginal Fine and Gray, and marginal multi-state models. For each model, we found that adjusting for the intraclass correlations through the sandwich variance estimator effectively maintained the type I error rate when the number of clusters is large. With no more than 30 clusters, however, the sandwich variance estimator can exhibit notable negative bias, and a permutation test provides better control of type I error inflation. Under the alternative, the...

STRIDE Acknowledgements. (DOCX 32 kb)

Rules for Adjudicating. (PDF 266 kb)

STRIDE Adjudication System Instructions. (PDF 539 kb)

Clinical Trials, 2021

Background/Aim In clinical trials, there is potential for bias from unblinded observers that may ... more Background/Aim In clinical trials, there is potential for bias from unblinded observers that may influence ascertainment of outcomes. This issue arose in the Strategies to Reduce Injuries and Develop Confidence in Elders trial, a cluster randomized trial to test a multicomponent intervention versus enhanced usual care (control) to prevent serious fall injuries, originally defined as a fall injury leading to medical attention. An unblinded nurse falls care manager administered the intervention, while the usual care arm did not involve contact with a falls care manager. Thus, there was an opportunity for falls care managers to refer participants reporting falls to seek medical attention. Since this type of observer bias could not occur in the usual care arm, there was potential for additional falls to be reported in the intervention arm, leading to dilution of the intervention effect and a reduction in study power. We describe the clinical basis for ascertainment bias, the statistical...

Innovation in Aging, 2017

for intrarater reliability. The administration time of the tool was 2.6 minutes on average (sd = ... more for intrarater reliability. The administration time of the tool was 2.6 minutes on average (sd = 0.9). Data on predictive validity in a cohort of 2,691 hospitalized older patients will be available soon and reported as well.

Cerebral Cortex, Mar 1, 2003

Cognitive, Affective, & Behavioral Neuroscience, Sep 1, 2005

Institutes of Health (MH 62196). We thank Todd Constable and Rob Fulbright for helpful discussion... more Institutes of Health (MH 62196). We thank Todd Constable and Rob Fulbright for helpful discussions regarding f MRI procedures, Hedy Sarofin for technical assistance in f MRI data collection, and Joe McGuire for assistance in conducting Experiment 6A and in preparing figures. Correspondence relating to this article may be sent to M.

Journal of Cognitive Neuroscience, Apr 1, 2006

& To investigate whether emotional arousal affects memorial feature binding, we had participants ... more & To investigate whether emotional arousal affects memorial feature binding, we had participants complete a short-term source-monitoring task-remembering the locations of four different pictures over a brief delay. On each trial, the four pictures were all either high arousal, medium arousal, or low arousal. Memory for picture-location conjunctions decreased as arousal increased. In addition, source memory for the location of negative pictures was worse among participants with higher depression scores. Two subsequent functional magnetic resonance imaging experiments showed that relative to low-arousal trials, high-and medium-arousal trials resulted in greater activity in areas associated with visual processing (fusiform gyrus, middle temporal gyrus/middle occipital gyrus, lingual gyrus) and less activity in superior precentral gyrus and the precentral-superior temporal intersect. These findings suggest that arousal (and perhaps negative valence for depressed people) recruits attention to items thereby disrupting working memory processes that help bind features together. &

Physical review, Oct 1, 1991

Neuroreport, Oct 2, 2006

We investigated the hypothesis that arousal recruits attention to item information, thereby disru... more We investigated the hypothesis that arousal recruits attention to item information, thereby disrupting working memory processes that help bind items to context. Using functional magnetic resonance imaging, we compared brain activity when participants remembered negative or neutral picture^location conjunctions (source memory) versus pictures only. Behaviorally, negative trials showed disruption of short-term source, but not picture, memory; long-term picture recognition memory was better for negative than for neutral pictures. Activity in areas involved in working memory and feature integration (precentral gyrus and its intersect with superior temporal gyrus) was attenuated on negative compared with neutral source trials relative to picture-only trials. Visual processing areas (middle occipital and lingual gyri) showed greater activity for negative than for neutral trials, especially on picture-only trials.

Recurrent event data are common in clinical studies when participants are followed longitudinally... more Recurrent event data are common in clinical studies when participants are followed longitudinally, and are often subject to a terminal event. With the increasing popularity of large pragmatic trials and a heterogeneous source population, participants are often nested in clinics and can be either susceptible or structurally unsusceptible to the recurrent process. These complications require new modeling strategies to accommodate potential zero-event inflation as well as hierarchical data structures in both the terminal and non-terminal event processes. In this paper, we develop a Bayesian semiparametric model to jointly characterize the zero-inflated recurrent event process and the terminal event process. We use a point mass mixture of non-homogeneous Poisson processes to describe the recurrent intensity and introduce shared random effects from different sources to bridge the non-terminal and terminal event processes. To achieve robustness, we consider nonparametric Dirichlet process...