Vortex formation and dissolution in sheared sands

Using digital image correlation, we track the displacement fluctuations within a persistent shear band in a dense sand specimen bounded by glass walls undergoing plane strain compression. The data evidences a clear, systematic, temporally recurring pattern of vortex formation, dissolution, and reformation throughout macroscopic softening and critical state regimes. During softening, locally affine deformation zones are observed at various locations along the shear band, which we argue to be kinematic signatures of semi-stable force chains. Force chain collapse then occurs, inducing vortex formation. Local jamming at the conflux of opposing displacements between adjacent vortices arrests the vortices, providing an avenue for potential new force chains to form amidst these jammed regions. The process repeats itself temporally throughout the critical state. The pattern further correlates with fluctuations in macroscopic shear stress. We characterize the nature of the observed vortices, as they are different in our sands comprised of irregular shaped particles, as compared to previous observations from experiments and numerical simulations which involved circular or rounded particles. The results provide an interesting benchmark for behavior of non-circular/non-spherical particles undergoing shear.National Science Foundation (U.S.) (grant CMMI-0748284)University of Southern CaliforniaUniversity of Southern California Women in Science and Engineering (WiSE) Progra

The impact of society on volunteered geographic information: The case of OpenStreetMap

Volunteered Geographical Information (VGI) has been extensively studied in terms of its quality and completeness in the past. However, little attention is given to understanding what factors, beyond individuals’ expertise, contribute to the success of VGI. In this chapter we ask whether society and its characteristics such as socio-economic factors have an impact on what part of the physical world is being digitally mapped. This question is necessary, so to understand where crowd-sourced map information can be relied upon (and crucially where not), with direct implications on the design of applications that rely on having complete and unbiased map knowledge. To answer the above questions, we study over 6 years of crowd-sourced contributions to OpenStreetMap (OSM) a successful example of the VGI paradigm. We measure the positional and thematic accuracy as well as completeness of this information and quantify the role of society on the state of this digital production. Finally we quantify the effect of social engagement as a method of intervention for improving users’ participation

Associations Between Early Maternal Depressive Symptom Trajectories And Toddlers’ Felt Security At 18 Months: Are Boys And Girls At Differential Risk?

The goal of this study was to evaluate whether there are sex differences in children’s vulnerability to caregiving risk, as indexed by trajectories of maternal depressive symptoms assessed from 2 to 18 monthsâ postpartum, and children’s rated attachment security in toddlerhood, adjusting for maternal social support and demographic risk. Analyses utilized longitudinal data collected for 182 African American motherâ child dyads from economically diverse backgrounds. Participants were recruited at the time of the child’s birth and followed to 18 monthsâ postpartum. Results of conditional latent growth models indicated that an increasing rate of change in level of maternal depressive symptoms over time negatively predicted toddlersâ felt attachment security. Higher social support was associated with decreasing levels of maternal depressive symptoms over time whereas higher demographic risk was associated with increasing levels of maternal depressive symptoms. A subsequent multigroup conditional latent growth model revealed that child sex moderated these associations. For male (but not female) children, a rapid increase in maternal depressive symptoms was associated with lower felt attachment security at 18 months. These findings suggest that boys, as compared to girls, may be more vulnerable to early caregiving risks such as maternal depression, with negative consequences for motherâ child attachment security in toddlerhood.RESUMENEl objetivo de este estudio fue evaluar si hay diferencias de sexo en la vulnerabilidad de los niños al riesgo de prestación de cuidado, como han indicado las trayectorias de síntomas depresivos maternos evaluadas de 2 a 18 meses después del parto, y el puntaje de la seguridad de afectividad de los niños en su temprana infancia, con ajustes basados en el apoyo social materno y el riesgo demográfico. Los análisis utilizaron información longitudinal recogida de 182 díadas de madreâ niño afroâ americanas de niveles económicamente diversos. Los participantes fueron reclutados al nacer el niño y se les dio seguimiento hasta los 18 meses después del parto. Los resultados de modelos de modelos de crecimiento latente condicionales indicaron que un incremento en el puntaje de cambio en el nivel de síntomas depresivos maternos a través del tiempo negativamente predijo la seguridad afectiva que los infantes sentían. Se asoció un más alto apoyo social con decrecientes niveles de síntomas depresivos maternos a través del tiempo, mientras que más altos riesgos demográficos se asociaron con un incrementos en los niveles de síntomas depresivos maternos. Un subsecuente modelo de crecimiento latente condicional reveló que el sexo del niño moderaba estas asociaciones. En el caso de niños varones (no así las niñas), se asoció un rápido incremento en síntomas depresivos maternos con más bajos niveles, a los 18 meses, de seguridad en la afectividad sentida. Estos resultados sugieren que los niños varones, comparados con las niñas, pudieran ser más vulnerables a los riesgos de un cuidado temprano tal como la depresión materna, con consecuencias negativas para la seguridad en la afectividad madreâ niño en la más temprana infancia.Rà SUMà Le but de cette étude était dâ évaluer s’il existe des différences entre les sexes dans la vulnérabilité des enfants au risque de la personne prenant soin d’eux, telle qu’elle est indexée par les trajectoires des symptômes dépressifs maternels évalués de 2 à 18 mois après la naissance, et la sécurité de l’attachement telle qu’elle est évaluée chez les enfants durant la petite enfance, s’ajustant au soutien social maternel et au risque démographique. Les analyses ont utilisé des données longitudinales recueillies pour 182 dyades mèresâ enfants noires américaines issues de milieux socioéconomiques divers. Les participants ont été recrutés au moment de la naissance de l’enfant et ont été suivis jusquâ à 18 mois après la naissance. Les résultats de modèles de croissance latents conditionnels ont indiqué qu’un taux croissant de changement dans le niveau des symptômes dépressifs maternels au fil du temps prédisait de manière négative la sécurité de l’attachement ressentie des jeunes enfants. Un soutien social plus élevé était lié à des niveaux décroissants de symptômes dépressifs maternels au fil du temps, alors qu’un risque démographique élevé était lié à des niveaux plus élevés de symptômes dépressifs maternels. Un modèle de croissance latente conditionnelle subséquente et multiâ groupe a révélé que le sexe de l’enfant modérait ces associations. Pour les enfants mâles (mais pas les enfants femelles) une augmentation rapide des symptômes dépressifs maternels était liée à une sécurité perçue de l’attachement plus basse à 18 mois. Ces résultats suggèrent que les garçons, comparés aux filles, peuvent être plus vulnérables aux risques liés à la personne prenant soin d’eux comme la dépression maternelle, avec des conséquences négatives pour la sécurité de l’attachement mèreâ enfant dans la petite enfance.ZUSAMMENFASSUNGDas Ziel dieser Studie war es, Geschlechtsunterschiede bei Kindern im Hinblick auf ihre Vulnerabilität bei Fürsorgerisiken zu evaluieren. Die Fürsorgerisiken wurden durch den Verlauf der mütterlichen depressiven Symptome von 2 bis 18 Monaten nach der Geburt indiziert, sowie durch die bewertete Bindungssicherheit der Kleinkinder. Dabei wurde für mütterliche soziale Unterstützung und demografische Risiken kontrolliert. Für die Analysen wurden Längsschnittdaten von 182 afroâ amerikanischen Mutterâ Kindâ Dyaden mit verschiedenen ökonomischen Hintergründen genutzt. Die Teilnehmer wurden zum Zeitpunkt der Geburt des Kindes rekrutiert und nach der Geburt für 18 Monate begleitet. Die Ergebnisse der konditionalen latenten Wachstumsmodelle zeigten, dass im Verlauf ansteigende mütterliche depressive Symptome mit der gefühlten Bindungssicherheit der Kleinkinder in einem negativen Vorhersagezusammenhang standen. Höhere soziale Unterstützung war mit einer Abnahme der mütterlichen depressiven Symptome im Verlauf der Zeit assoziiert, während ein höheres demografisches Risiko mit dem Anstieg der mütterlichen depressive Symptome assoziiert war. Ein nachfolgendes konditionales latentes Wachstumsmodell für multiple Gruppen zeigte, dass das Geschlecht des Kindes diese Assoziationen moderierte. Bei Jungen (jedoch nicht bei Mädchen) war eine rasche Zunahme der mütterlichen depressiven Symptome mit einer niedrigeren gefühlten Bindungssicherheit 18 Monate nach der Geburt assoziiert. Diese Ergebnisse deuten darauf hin, dass Jungen, verglichen mit Mädchen, hinsichtlich früher Fürsorgerisiken wie mütterlicher Depression vulnerabler sind, was wiederum mit negativen Folgen für die Bindungssicherheit zwischen Mutter und Kind im Kleinkindalter einhergehen kann.æ é ²ã ã ®ç  ç©¶ã ®ç ®ç ã ¯ã é¤ è ²ã ®ã ªã ¹ã ¯ã ¸ã ®å­ ã ©ã ã ®è å¼±æ §ã «æ §å·®ã ã ã ã ã ©ã ã ã è© ä¾¡ã ã ã 㠨㠧ã ã ã ã ã ã ¯ã å ºç £å¾ 2â ¼18ã æ ã «è© ä¾¡ã ã ã æ¯ è¦ªã ®æ ã ã ¤ç ç ¶ã ®çµ é 㠨幼å æ ã «è© å® ã ã ã ã ã ©ã ã ®æ ç ã ®å® å® æ §ã æ æ¨ ã «ã ã ¦ã æ¯ è¦ªã ®ç¤¾ä¼ ç æ ¯æ ´ã ¨äººå £çµ±è¨ å­¦ç 㠪㠹㠯㠫㠤ã ã ¦é ©å ã ã ã ã å æ ã ¯ã çµ æ¸ ç ã «å¤ æ§ ã ªè æ ¯ã æ ã ¤182çµ ã ®ã ¢ã ã ªã «ç³»ã ¢ã ¡ã ªã «äººã ®æ¯ å­ ã ã é ã ã ã ã ç¸¦æ ­ç ã ªã 㠼㠿ã å ©ç ¨ã ã ã ç  ç©¶å å  è ã ¯å­ ã ©ã ã ®å ºç æ ã «é ã ã ã ã ç £å¾ 18ã æ é 追跡ã ã ã ã æ ¡ä»¶ä» ã æ½ å ¨æ é ·ã ¢ã ã «ã ®çµ æ ã ã ã æ é çµ é ã «ã ã æ¯ è¦ªã ®æ ã ã ¤ç ç ¶ã ¬ã ã «ã ®å¤ å ç ã ®å¢ å  ã ¯ã å¹¼å ã «æ ã ã ã ã æ ç ã ®å® å® æ §ã ã ã ¬ã ã £ã ã «äº æ¸¬ã ã ã ã ¨ã 示ã ã ã ã ã ã é« ã ç¤¾ä¼ æ ¯æ ´ã ¯ã æ é çµ é ã «ã ã æ¯ è¦ªã ®æ ã ã ¤ç ç ¶ã ¬ã ã «ã ®ä½ ä¸ ã «é ¢é £ã ã ã ã ã ã ®ä¸ æ ¹ã ã é« ã äººå £çµ±è¨ å­¦ç ã ªã ¹ã ¯ã ¯æ¯ è¦ªã ®æ ã ã ¤ç ç ¶ã ¬ã ã «ã ®å¢ å  ã ¨é ¢é £ã ã ã ã ã ã «ç¶ ã å¤ ç¾¤æ ¡ä»¶ä» ã æ½ å ¨æ é ·ã ¢ã ã «ã ã ã å­ ã ©ã ã ®æ §å ¥ã ã ã ã ã ®é ¢é £ã ç·©å ã ã ã ç ·å 㠧㠯 (ã ã ã 女å 㠧㠯㠪ã ) ã æ ¥é ã «å¢ å¤§ã ã æ¯ è¦ªã ®æ ã ã ¤ç ç ¶ã ¯ã 18ã æ ã §æ ã ã ã ã æ ç ã ®å® å® æ §ã ®ä½ ã ã ¨é ¢é £ã ã ã ã ã ã ã ®çµ æ ã ã ã 女å ã «æ¯ ã ¹ã ¦ç ·å ã ¯ã æ¯ è¦ªã ®æ ã 㠤㠮ã ã ã ªæ ©æ ã ®é¤ è ²ã ªã ¹ã ¯ã «å¯¾ã ã ¦ã ã è 弱㠧ã ã ã å¹¼å æ ã ®æ¯ å­ ã ®æ ç ã ®å® å® æ §ã «ã ã ¬ã ã £ã ã ªçµ æ ã ã ã ã ã ã ¦ã ã ã æ è¦ æ ¬ç  ç©¶ç ç ®ç æ ¯è© ä¼°å ç«¥ç §é¡§é¢¨é ªç è å¼±æ §æ ¯å ¦å­ å ¨æ §å ¥å·®ç °, ä½ è æ ¹æ ç ¢å¾ 2è ³18å æ ç ç ¢å©¦æ 鬱ç ç ç è» è·¡, å å ç«¥å ¨å¹¼å æ ç é¡ å® ä¾ é å® å ¨æ è© ä¼°, ä¸¦èª¿æ ´æ¯ è¦ªç 社æ æ ¯æ å äººå £é¢¨é ªã ç  ç©¶å æ ä½¿ç ¨å¾ 182å ä¾ è ªç¶ æ¿ å¤ æ¨£å è æ ¯ç ç¾ å é æ´²è£ æ¯ å­ äº äººçµ å ç 縱å æ ¸æ ã å è è å ¨å­©å­ å ºç æ æ å , ç ¶å¾ è· é ²å °ç ¢å¾ 18å æ ã æ¢ ä»¶æ½ å ¨ç é ·æ¨¡å ç çµ æ 表æ , é ¨è æ é ç æ ¨ç§», æ¯ è¦ªæ 鬱ç ç ç å¢ å  ç , è² é ¢å °é  æ¸¬å¹¼å ç ä¾ é å® å ¨æ ã è¼ é« ç 社æ æ ¯æ è æ¯ è¦ªæ 鬱ç ç ç é ä½ ç ¸é , è è¼ é« ç äººå £é¢¨é ªè æ¯ è¦ªæ 鬱ç ç ç å¢ å  ç ¸é ã é ¨å¾ ç å¤ çµ æ¢ ä»¶æ½ å ¨ç é ·æ¨¡å å æ 顯示, å ç«¥æ §å ¥ç·©å é é ä¿ ã å° æ ¼ç ·å­© (ä½ ä¸ æ ¯å¥³å­©) , æ¯ è¦ªæ 鬱ç ç ç å¿«é å¢ å  è 18å æ æ è¼ ä½ ç ä¾ é å® å ¨æ æ é ã é äº ç  ç©¶çµ æ 表æ , è å¥³å­©ç ¸æ¯ , ç ·å­©å ¯è ½æ ´å®¹æ å å °æ ©æ ç §é¡§é¢¨é ª, ä¾ å¦ ç ¢å©¦æ 鬱ç , å° å¹¼å æ æ¯ å­ ä¾ é å® å ¨æ å¸¶ä¾ ç è² é ¢å½±é ¿ãPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135990/1/imhj21617.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135990/2/imhj21617_am.pd

Lifestyle and self-rated health: a cross-sectional study of 3,601 citizens of Athens, Greece

<p>Abstract</p> <p>Background</p> <p>Self-rated health (SRH) is a popular health measure determined by multiple factors. International literature is increasingly focusing on health-related behaviors such as smoking, dietary habits, physical activity, even religiosity. However, population-based studies taking into account multiple putative determinants of SRH in Greece are scarce. The aim of this study was to clarify possible determinants of SRH with an emphasis on the relationship between SRH and lifestyle variables in a large sample of urban citizens.</p> <p>Methods</p> <p>In this one-year cross-sectional study, a stratified random sample of 3,601 urban citizens was selected. Data were collected using an interview-based questionnaire about various demographic, socioeconomic, disease- and lifestyle related factors such as smoking, physical activity, dietary habits, sleep quality and religiosity. Multivariate logistic regression was used separately in three age groups [15-29 (N = 1,360), 30-49 (N = 1,122) and 50+ (N = 1,119) years old] in order to identify putative lifestyle and other determinants of SRH.</p> <p>Results</p> <p>Reporting of good SRH decreased with age (97.1%, 91.4% and 74.8%, respectively). Overall, possible confounders of the lifestyle-SRH relationship among age groups were sex, education, hospitalization during the last year, daily physical symptoms and disease status. Poor SRH was associated with less physical activity in the 15-29 years old (OR 2.22, 95%CI 1.14-4.33), with past or heavy smoking, along with no sleep satisfaction in the 30-49 years old (OR 3.23, 95%CI 1.35-7.74, OR 2.56, 95%CI 1.29-5.05, OR 1.79, 95%CI 1.1-2.92, respectively) and with obesity and no sleep satisfaction in the 50+ years old individuals (OR 1.83, 95%CI 1.19-2.81, OR 2.54, 95%CI 1.83-3.54). Sleep dissatisfaction of the 50+ years old was the only variable associated with poor SRH at the 0.001 p level of significance (OR 2.45, 99%CI 1.59 to 3.76). Subgroup analyses of the 15-19 years old individuals also revealed sleep dissatisfaction as the only significant variable correlated with SRH.</p> <p>Conclusions</p> <p>Slight differences in lifestyle determinants of SRH were identified among age groups. Sleep quality emerged as an important determinant of SRH in the majority of participants.</p

Cross-sectional associations between multiple lifestyle behaviors and health-related quality of life in the 10,000 steps cohort

Background: The independent and combined influence of smoking, alcohol consumption, physical activity, diet, sitting time, and sleep duration and quality on health status is not routinely examined. This study investigates the relationships between these lifestyle behaviors, independently and in combination, and health-related quality of life (HRQOL). Methods: Adult members of the 10,000 Steps project (n = 159,699) were invited to participate in an online survey in November-December 2011. Participant socio-demographics, lifestyle behaviors, and HRQOL (poor self-rated health; frequent unhealthy days) were assessed by self-report. The combined influence of poor lifestyle behaviors were examined, independently and also as part of two lifestyle behavior indices, one excluding sleep quality (Index 1) and one including sleep quality (Index 2). Adjusted Cox proportional hazard models were used to examine relationships between lifestyle behaviors and HRQOL. Results: A total of 10,478 participants provided complete data for the current study. For Index 1, the Prevalence Ratio (p value) of poor self-rated health was 1.54 (p = 0.001), 2.07 (p≤0.001), 3.00 (p≤0.001), 3.61 (p≤0.001) and 3.89 (p≤0.001) for people reporting two, three, four, five and six poor lifestyle behaviors, compared to people with 0-1 poor lifestyle behaviors. For Index 2, the Prevalence Ratio (p value) of poor self-rated health was 2.26 (p = 0.007), 3.29 (p≤0.001), 4.68 (p≤0.001), 6.48 (p≤0.001), 7.91 (p≤0.001) and 8.55 (p≤0.001) for people reporting two, three, four, five, six and seven poor lifestyle behaviors, compared to people with 0-1 poor lifestyle behaviors. Associations between the combined lifestyle behavior index and frequent unhealthy days were statistically significant and similar to those observed for poor self-rated health. Conclusions: Engaging in a greater number of poor lifestyle behaviors was associated with a higher prevalence of poor HRQOL. This association was exacerbated when sleep quality was included in the index. © 2014 Duncan et al