Dynamical system analysis and forecasting of deformation produced by an earthquake fault

We present a method of constructing low-dimensional nonlinear models describing the main dynamical features of a discrete 2D cellular fault zone, with many degrees of freedom, embedded in a 3D elastic solid. A given fault system is characterized by a set of parameters that describe the dynamics, rheology, property disorder, and fault geometry. Depending on the location in the system parameter space we show that the coarse dynamics of the fault can be confined to an attractor whose dimension is significantly smaller than the space in which the dynamics takes place. Our strategy of system reduction is to search for a few coherent structures that dominate the dynamics and to capture the interaction between these coherent structures. The identification of the basic interacting structures is obtained by applying the Proper Orthogonal Decomposition (POD) to the surface deformations fields that accompany strike-slip faulting accumulated over equal time intervals. We use a feed-forward artificial neural network (ANN) architecture for the identification of the system dynamics projected onto the subspace (model space) spanned by the most energetic coherent structures. The ANN is trained using a standard back-propagation algorithm to predict (map) the values of the observed model state at a future time given the observed model state at the present time. This ANN provides an approximate, large scale, dynamical model for the fault.Comment: 30 pages, 12 figure

Particulate matter exposure during pregnancy is associated with birth weight, but not gestational age, 1962-1992: a cohort study

<p>Abstract</p> <p>Background</p> <p>Exposure to air pollutants is suggested to adversely affect fetal growth, but the evidence remains inconsistent in relation to specific outcomes and exposure windows.</p> <p>Methods</p> <p>Using birth records from the two major maternity hospitals in Newcastle upon Tyne in northern England between 1961 and 1992, we constructed a database of all births to mothers resident within the city. Weekly black smoke exposure levels from routine data recorded at 20 air pollution monitoring stations were obtained and individual exposures were estimated via a two-stage modeling strategy, incorporating temporally and spatially varying covariates. Regression analyses, including 88,679 births, assessed potential associations between exposure to black smoke and birth weight, gestational age and birth weight standardized for gestational age and sex.</p> <p>Results</p> <p>Significant associations were seen between black smoke and both standardized and unstandardized birth weight, but not for gestational age when adjusted for potential confounders. Not all associations were linear. For an increase in whole pregnancy black smoke exposure, from the 1^st(7.4 μg/m³) to the 25^th(17.2 μg/m³), 50^th(33.8 μg/m³), 75^th(108.3 μg/m³), and 90^th(180.8 μg/m³) percentiles, the adjusted estimated decreases in birth weight were 33 g (SE 1.05), 62 g (1.63), 98 g (2.26) and 109 g (2.44) respectively. A significant interaction was observed between socio-economic deprivation and black smoke on both standardized and unstandardized birth weight with increasing effects of black smoke in reducing birth weight seen with increasing socio-economic disadvantage.</p> <p>Conclusions</p> <p>The findings of this study progress the hypothesis that the association between black smoke and birth weight may be mediated through intrauterine growth restriction. The associations between black smoke and birth weight were of the same order of magnitude as those reported for passive smoking. These findings add to the growing evidence of the harmful effects of air pollution on birth outcomes.</p

Development and validation of a risk prediction model for 1-year readmission among young adults hospitalized for acute myocardial infarction

BACKGROUND: Readmission over the first year following hospitalization for acute myocardial infarction (AMI) is common among younger adults (≤55 years). Our aim was to develop/validate a risk prediction model that considered a broad range of factors for readmission within 1 year. METHODS AND RESULTS: We used data from the VIRGO (Variation in Recovery: Role of Gender on Outcomes of Young AMI Patients) study, which enrolled young adults aged 18 to 55 years hospitalized with AMI across 103 US hospitals (N=2979). The primary outcome was ≥1 all-cause readmissions within 1 year of hospital discharge. Bayesian model averaging was used to select the risk model. The mean age of participants was 47.1 years, 67.4% were women, and 23.2% were Black. Within 1 year of discharge for AMI, 905 (30.4%) of participants were readmitted and were more likely to be female, Black, and nonmarried. The final risk model consisted of 10 predictors: depressive symptoms (odds ratio [OR], 1.03; 95% CI, 1.01–1.05), better physical health (OR, 0.98; 95% CI, 0.97–0.99), in-hospital complication of heart failure (OR, 1.44; 95% CI, 0.99–2.08), chronic obstructive pulmomary disease (OR, 1.29; 95% CI, 0.96–1.74), diabetes mellitus (OR, 1.23; 95% CI, 1.00–1.52), female sex (OR, 1.31; 95% CI, 1.05–1.65), low income (OR, 1.13; 95% CI, 0.89–1.42), prior AMI (OR, 1.47; 95% CI, 1.15–1.87), in-hospital length of stay (OR, 1.13; 95% CI, 1.04–1.23), and being employed (OR, 0.88; 95% CI, 0.69–1.12). The model had excellent calibration and modest discrimination (C statistic=0.67 in development/validation cohorts). CONCLUSIONS: Women and those with a prior AMI, increased depressive symptoms, longer inpatient length of stay and diabetes may be more likely to be readmitted. Notably, several predictors of readmission were psychosocial characteristics rather than markers of AMI severity. This finding may inform the development of interventions to reduce readmissions in young patients with AMI

Gender differences in the trajectory of recovery in health status among young patients with acute myocardial infarction: results from the variation in recovery: Role of gender on outcomes of young AMI patients (VIRGO) study

Background: Despite the excess risk of mortality in young women (≤55 years of age) after acute myocardial infarction (AMI), little is known about young women's health status (symptoms, functioning, quality of life) during the first year of recovery after an AMI. We examined gender differences in health status over time from baseline to 12 months after AMI. Methods and Results: A total of 3501 AMI patients (67% women) 18 to 55 years of age were enrolled from 103 US and 24 Spanish hospitals. Data were obtained by medical record abstraction and patient interviews at baseline hospitalization and 1 and 12 months after AMI. Health status was measured by generic (Short Form-12) and disease-specific (Seattle Angina Questionnaire) measures. We compared health status scores at all 3 time points and used longitudinal linear mixed-effects analyses to examine the independent effect of gender, adjusting for time and selected covariates. Women had significantly lower health status scores than men at each assessment (all P values <0.0001). After adjustment for time and all covariates, women had Short Form-12 physical/mental summary scores that were -0.96 (95% confidence interval [CI], -1.59 to -0.32) and -2.36 points (95% CI, -2.99 to -1.73) lower than those of men, as well as worse Seattle Angina Questionnaire physical limitations (-2.44 points lower; 95% CI, -3.53 to -1.34), more angina (-1.03 points lower; 95% CI, -1.98 to -0.07), and poorer quality of life (-3.51 points lower; 95% CI, -4.80 to -2.22). Conclusion: Although both genders recover similarly after AMI, women have poorer scores than men on all health status measures, a difference that persisted throughout the entire year after discharge.Rachel P. Dreyer, Yongfei Wang, Kelly M. Strait, Nancy P. Lorenze, Gail D’Onofrio, Héctor Bueno, Judith H. Lichtman, John A. Spertus, Harlan M. Krumhol

Sex differences in perceived stress and early recovery in young and middle-aged patients with acute myocardial infarction

Published online before print February 9, 2015BACKGROUND: Younger age and female sex are both associated with greater mental stress in the general population, but limited data exist on the status of perceived stress in young and middle-aged patients presenting with acute myocardial infarction. METHODS AND RESULTS: We examined sex difference in stress, contributing factors to this difference, and whether this difference helps explain sex-based disparities in 1-month recovery using data from 3572 patients with acute myocardial infarction (2397 women and 1175 men) 18 to 55 years of age. The average score of the 14-item Perceived Stress Scale at baseline was 23.4 for men and 27.0 for women (P<0.001). Higher stress in women was explained largely by sex differences in comorbidities, physical and mental health status, intrafamily conflict, caregiving demands, and financial hardship. After adjustment for demographic and clinical characteristics, women had worse recovery than men at 1 month after acute myocardial infarction, with mean differences in improvement score between women and men ranging from -0.04 for EuroQol utility index to -3.96 for angina-related quality of life (P<0.05 for all). Further adjustment for baseline stress reduced these sex-based differences in recovery to -0.03 to -3.63, which, however, remained statistically significant (P<0.05 for all). High stress at baseline was associated with significantly worse recovery in angina-specific and overall quality of life, as well as mental health status. The effect of baseline stress on recovery did not vary between men and women. CONCLUSIONS: Among young and middle-aged patients, higher stress at baseline is associated with worse recovery in multiple health outcomes after acute myocardial infarction. Women perceive greater psychological stress than men at baseline, which partially explains women's worse recovery.Xiao Xu, Haikun Bao, Kelly Strait, John A. Spertus, Judith H. Lichtman, Gail D, Onofrio, Erica Spatz, Emily M. Bucholz, Mary Geda, Nancy P. Lorenze, Héctor Bueno, John F. Beltrame, Harlan M. Krumhol

Gender differences in pre-event health status of young patients with acute myocardial infarction: A VIRGO study analysis

Aims: We assessed gender differences in pre-event health status (symptoms, functioning, quality of life) in young patients with acute myocardial infarction and whether or not this association persists following sequential adjustment for important covariates. We also evaluated the interaction between gender and prior coronary artery disease, given that aggressive symptom control is a cornerstone of care in those with known coronary disease. Methods and results: A total of 3501 acute myocardial infarction patients (2349 women) aged 18–55 years were enrolled from 103 US/24 Spanish hospitals (2008–2012). Clinical/health status information was obtained by medical record abstraction and patient interviews. Pre-event health status was measured by generic (Short Form-12, EuroQoL) and disease-specific (Seattle Angina Questionnaire) measures. T-test/chi-square and multivariable linear/logistic regression analysis was utilized, sequentially adjusting for covariates. Women had more co-morbidities and significantly lower generic mean health scores than men (Short Form-12 physical health = 43±12 vs. 46±11 and mental health = 44±13 vs. 48±11); EuroQoL utility index = 0.7±0.2 vs. 0.8±0.2 and visual analog scale = 63±22 vs. 67±20, P < 0.0001 for all. Their disease-specific health status was also worse, with more angina (Seattle Angina Questionnaire angina frequency = 83±22 vs. 87±18), worse physical function (physical limitation = 78±27 vs. 87±21) and poorer quality of life (55±25 vs. 60±22, P<0.0001 for all). In multivariable analysis, the association between female gender and worse generic physical/mental health persisted, as well as worse disease-specific physical limitation and quality of life. The interaction between gender and prior coronary artery disease was not significant in any of the health status outcomes. Conclusion: Young women have worse pre-event health status as compared with men, regardless of their coronary artery disease history. While future studies of gender differences should adjust for baseline health status, an opportunity may exist to better address the pre-event health status of women at risk for acute myocardial infarction.Keywords: Health status, women, acute myocardial infarction, quality of lif

Sexual activity and counseling in the first month after acute myocardial infarction among younger adults in the United States and Spain: a prospective, observational study

Background— United States and European cardiovascular society guidelines recommend physicians counsel patients about resuming sexual activity after acute myocardial infarction (AMI), but little is known about patients’ experience with counseling about sexual activity after AMI. Methods and Results— The prospective, longitudinal Variation in Recovery: Role of Gender on Outcomes of Young AMI Patients (VIRGO) study, conducted at 127 hospitals in the United States and Spain, was designed, in part, to evaluate gender differences in baseline sexual activity, function, and patient experience with physician counseling about sexual activity after an AMI. This study used baseline and 1-month data collected from the 2:1 sample of women (N=2349) and men (N=1152) ages 18 to 55 years with AMI. Median age was 48 years. Among those who reported discussing sexual activity with a physician in the month after AMI (12% of women, 19% of men), 68% were given restrictions: limit sex (35%), take a more passive role (26%), and/or keep the heart rate down (23%). In risk-adjusted analyses, factors associated with not discussing sexual activity with a physician included female gender (relative risk, 1.07; 95% confidence interval, 1.03–1.11), age (relative risk, 1.05 per 10 years; 95% confidence interval, 1.02–1.08), and sexual inactivity at baseline (relative risk, 1.11; 95% confidence interval, 1.08–1.15). Among patients who received counseling, women in Spain were significantly more likely to be given restrictions than U.S. women (relative risk; 1.36, 95% confidence interval, 1.11–1.66). Conclusions— Very few patients reported counseling for sexual activity after AMI. Those who did were commonly given restrictions not supported by evidence or guidelines. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00597922.Stacy Tessler Lindau, Emily M. Abramsohn, Héctor Bueno, Gail D’Onofrio, Judith H. Lichtman ... John A. Spertus ... et al