Action of a minimal contractile bactericidal nanomachine.

R-type bacteriocins are minimal contractile nanomachines that hold promise as precision antibiotics1-4. Each bactericidal complex uses a collar to bridge a hollow tube with a contractile sheath loaded in a metastable state by a baseplate scaffold1,2. Fine-tuning of such nucleic acid-free protein machines for precision medicine calls for an atomic description of the entire complex and contraction mechanism, which is not available from baseplate structures of the (DNA-containing) T4 bacteriophage5. Here we report the atomic model of the complete R2 pyocin in its pre-contraction and post-contraction states, each containing 384 subunits of 11 unique atomic models of 10 gene products. Comparison of these structures suggests the following sequence of events during pyocin contraction: tail fibres trigger lateral dissociation of baseplate triplexes; the dissociation then initiates a cascade of events leading to sheath contraction; and this contraction converts chemical energy into mechanical force to drive the iron-tipped tube across the bacterial cell surface, killing the bacterium.

The Social Environment Matters for Telomere Length and Internalizing Problems During Adolescence.

Depression and anxiety symptoms are on the rise among adolescents. With increasing evidence that cellular aging may be associated with depressive and anxiety symptoms, there is an urgent need to identify the social environment context that may moderate this link. This study addresses this research gap by investigating the moderating role of the social environment on the relation between telomere length and emotional health among adolescents. Participants were 411 non-Hispanic (88.56%) Black (100%) adolescents (M = 14.23 years, SD = 1.85, female = 54%) in a major metropolitan city. Youth and parents reported on an array of social risk and protective factors, and youth provided DNA samples for telomere length measurement. Results demonstrated that the association of telomere length and anxiety symptoms was stronger among youth with higher perceived stress or lower school belongingness, and the association of telomere length with depressive symptoms was stronger under conditions of higher parent inter-partner psychological aggression. The results enhance our understanding of the complex associations between biological aging, the social environment, and mental health in adolescence.

Place-Based Developmental Research: Conceptual and Methodological Advances in Studying Youth Development in Context.

Scientists have, for some time, recognized that development unfolds in numerous settings, including families, schools, neighborhoods, and organized and unorganized activity settings. Since the turn of the 20th century, the body of mainstream neighborhood effects scholarship draws heavily from the early 20th century Chicago School of Sociology frameworks and have been situating development in neighborhood contexts and working to identify the structures and processes via which neighborhoods matter for a range of developmental outcomes, especially achievement, behavioral and emotional problems, and sexual activity. From this body of work, two new areas of developmental scholarship are emerging. Both areas are promising for advancing an understanding of child development in context. First, cultural-developmental neighborhood researchers are advancing neighborhood effects research that explicitly recognizes the ways that racial, ethnic, cultural, and immigrant social positions matter for neighborhood environments and for youths' developmental demands, affordances, experiences, and competencies. This body of work substantially expands the range of developmental outcomes examined in neighborhood effects scholarship to recognize normative physical, emotional, cognitive, behavioral, social, and cultural competencies that have largely been overlooked in neighborhood effects scholarship that espoused a more color-blind developmental approach. Second, activity space neighborhood researchers are recognizing that residential neighborhoods have important implications for broader activity spaces-or the set of locations and settings to which youth are regularly exposed, including, for example, schools, work, organized activities, and hang-outs. They are using newer technologies and geographic frameworks to assess exposure to residential neighborhood and extra-neighborhood environments. These perspectives recognize that time (i.e., from microtime to mesotime) and place are critically bound and that exposures can be operationalized at numerous levels of the ecological system (i.e., from microsystems to macrosystems). These frameworks address important limitations of prior development in context scholarship by addressing selection and exposure. Addressing selection involves recognizing that families have some degree of choice when selecting into settings and variables that predict families' choices (e.g., income) also predict development. Considering exposure involves recognizing that different participants or residents experience different amounts of shared and nonshared exposures, resulting in both under-and over-estimation of contextual effects. Activity space scholars incorporate exposure to the residential neighborhood environments, but also to other locations and settings to which youth are regularly exposed, like schools, after-school settings, work, and hang-outs. Unfortunately, the cultural-development and activity space streams, which have both emerged from early 20th century work on neighborhood effects on development, have been advancing largely independently. Thus, the overarching aim of this monograph is to integrate scholarship on residential neighborhoods, cultural development, and activity spaces to advance a framework that can support a better understanding of development in context for diverse groups. In Chapters I and II we present the historical context of the three streams of theoretical, conceptual, and methodological research. We also advance a comprehensive cultural-developmental activity space framework for studying development in context among children, youth, and families that are ethnically, racially, and culturally heterogeneous. This framework actively recognized diversity in ethnic, racial, immigrant, and socioeconomic social positions. In Chapters III-V we advance specific features of the framework, focusing on: (1) the different levels of nested and nonnested ecological systems that can be captured and operationalized with activity space methods, (2) the different dimensions of time and exposures or experiences that can be captured and operationalized by activity space methods, and (3) the importance of settings structures and social processes for identifying underlying mechanisms of contextual effects on development. Structures are setting features related to the composition and spatial arrangement of people and institutions (e.g., socioeconomic disadvantage, ethnic/racial compositions). Social processes represent the collective social dynamics that take place in settings, like social interactions, group activities, experiences with local institutions, mechanisms of social control, or shared beliefs. In Chapter VI, we highlight a range of methodological and empirical exemplars from the United States that are informed by our comprehensive cultural-developmental activity space framework. These exemplars feature both quantitative and qualitative methods, including method mixing. These exemplars feature both quantitative and qualitative methods, including method mixing. The exemplars also highlight the application of the framework across four different samples from populations that vary in terms of race, ethnicity, gender, age, socioeconomic status (SES), geographic region, and urbanicity. They capture activity space characteristics and features in a variety of ways, in addition to incorporating family shared and nonshared activity space exposures. Finally, in Chapter VII we summarize the contributions of the framework for advancing a more comprehensive science of development in context, one that better realizes major developmental theories emphasizing persons, processes, contexts, and time. Additionally, we offer a place-based, culturally informed developmental research agenda to meet the needs of an increasingly diverse population.

Structure of the T4 baseplate and its function in triggering sheath contraction.

Several systems, including contractile tail bacteriophages, the type VI secretion system and R-type pyocins, use a multiprotein tubular apparatus to attach to and penetrate host cell membranes. This macromolecular machine resembles a stretched, coiled spring (or sheath) wound around a rigid tube with a spike-shaped protein at its tip. A baseplate structure, which is arguably the most complex part of this assembly, relays the contraction signal to the sheath. Here we present the atomic structure of the approximately 6-megadalton bacteriophage T4 baseplate in its pre- and post-host attachment states and explain the events that lead to sheath contraction in atomic detail. We establish the identity and function of a minimal set of components that is conserved in all contractile injection systems and show that the triggering mechanism is universally conserved.

Racial Inequalities in Adolescents' Exposure to Racial and Socioeconomic Segregation, Collective Efficacy, and Violence.

In the United States, Black youth tend to grow up in remarkably less resourced neighborhoods than White youth. This study investigates whether and to what extent Black youth are moreover exposed to less resourced activity spaces beyond the home. We draw on GPS data from a large sample of urban youth in the Columbus, Ohio-based Adolescent Health and Development in Context study (2014-2016) to examine to what extent Black youth experience nontrivial, disproportionate levels of exposure to more disadvantaged and segregated contexts in their daily routines compared with similarly residentially situated White youth. Specifically, we estimate Black-White differences in nonhome exposure to concentrated disadvantage, racial segregation, collective efficacy, and violent crime. We find that Black youths' activity spaces have substantially higher rates of racial segregation and violent crime than those of White youth, and substantially lower levels of collective efficacy-even after accounting for a host of individual- and home neighborhood-level characteristics. We find more modest evidence of differences in exposure to socioeconomic disadvantage. These findings have important implications for neighborhood-centered interventions focused on youth well-being and the contextual effects and segregation literatures more generally.

Demographic and health predictors of telomere length during adolescence.

Telomere length (TL) is proposed to play a mechanistic role in how the exposome affects health outcomes. Little is known about TL during adolescence, a developmental period during which precursors of adult-onset health problems often emerge. We examined health and demographic sources of variation in TL in 899 youth aged 11-17. Demographic and health information included age, sex, race, household income, caregiver age and marital status, youth tobacco exposure, body mass index, pubertal status, health problems, medication use, and season of data collection. Genomic DNA was extracted from saliva, and T/S ratios were computed following qPCR. Age, race, season of data collection, and household income were associated with the telomere to single copy (T/S) ratio. We found that T/S ratios were larger at younger ages, among Black youth, for saliva collected during autumn and winter, and among households with higher income. Analyses stratified by race revealed that the association between age and T/S ratio was present for Black youth, that season of collection was present across races, but that family demographic associations with T/S ratio varied by race. The results provide information for future telomere research and highlight adolescence as a potentially important developmental phase for racial disparities in telomere shortening and health.

Racial and Economic Adversity Differences in Stress Markers and Immune Function Among Urban Adolescents.

BACKGROUND: Exposure to racism and associated adversities, such as poverty, is hypothesized to contribute to racial inequities in health via stress and immune pathways. Furthermore, the effects of adversity may be more salient during sensitive developmental periods. Our study examined racial differences in stress and immune biomarkers during adolescence and the effects of exposure to economic adversity at distinct developmental time periods and cumulatively in accounting for potential racial differences. METHODS: Secondary analysis of the Adolescent Health and Development in Context study was conducted. Data were derived from self-administered surveys; interviews; smartphone-based, geographic-explicit ecological momentary assessment; stress biomarkers (evening salivary cortisol over six nights and hair cortisol); and immune biomarkers (salivary shedding of Epstein-Barr virus [EBV] DNA among EBV-positive adolescents). Current socioeconomic status measures included annual household income and caregiver education. Caregivers also reported experiences of bankruptcy, difficulty paying bills, receipt of food stamps/Supplemental Nutrition Assistance Program/electronic benefit transfer, and job loss when the child was of ages birth-5 years, 6-10 years, and 11 years or older. An affirmative response to any item was defined as exposure to economic adversity for that developmental time period (yes/no). A cumulative economic adversity measure was calculated as the sum of exposures across developmental periods (0 = never exposed to 3 = exposed across all time periods). Descriptive and multivariable regression analyses were conducted, accounting for covariates. RESULTS: Black/African American adolescents had higher salivary cortisol concentration, higher hair cortisol concentration, and an increased odd of salivary shedding of EBV DNA compared to White adolescents. Racial differences were not attenuated by the current socioeconomic status or economic adversity (developmental period or cumulatively). DISCUSSION: Our study provides evidence that stress and immune biomarkers differ by race as early as adolescence and may be one pathway through which racism and associated adversities contribute to racial health inequities. Further research on the contribution of multiple adversities beyond poverty to racial inequities in physiological stress and health is critical for informing effective prevention and intervention efforts.

Neighborhoods, Activity Spaces, and the Span of Adolescent Exposures.

Since the inception of urban sociology, the "neighborhood" has served as the dominant context thought to capture developmentally significant youth experiences beyond the home. Yet no large-scale study has examined patterns of exposure to the most commonly used operationalization of neighborhood - the census tract - among urban youth. Using smartphone GPS data from the Adolescent Health and Development in Context study (N=1405), we estimate the amount of time youth spend in residential neighborhoods and consider explanations for variation in neighborhood exposure. On average, youth (ages 11 to 17) spend 5.7% of their waking time in their neighborhood but not at home, 60% at home, and 34.3% outside their neighborhood. Multilevel negative binomial regression models indicate that residence in economically disadvantaged neighborhoods is associated with less time in neighborhood. Higher levels of local violence and the absence of a neighborhood school the youth is eligible to attend are negatively associated with time in neighborhood and mediate the concentrated disadvantage effect. Fractional multinomial logit models indicate that higher violence is linked with increased time at home while school absence is associated with increased outside-neighborhood time. Theoretical development and empirical research on neighborhood effects should incorporate findings on the extent and nature of neighborhood and broader activity space exposures among urban youth.

Syringe Service Program Utilization, Barriers, and Preferences for Design in Rural Appalachia: Differences between Men and Women Who Inject Drugs.

Background People who inject drugs (PWID) in rural areas of the United States have had limited access to syringe service programs (SSP). Rural SSP have recently surged, but accompanying research is lacking about PWID utilization, barriers, and preferences for SSP design and how those preferences vary by gender. Methods: Interviewer-administered surveys elicited information about utilization, barriers, and preferences for SSP design from 234 PWID recruited using respondent-driven sampling in Appalachian, Kentucky. Gender differences among reported barriers to utilizing SSP and preferences for program design were explored using Mantel-Haenszel chi-square tests. Results: Overall, 49% of PWID had ever utilized an SSP. The most common reasons for not utilizing an SSP were lack of awareness (23%), fear of being seen or disclosing drug use (19%), and lack of need (19%). The most preferred SSP design was located within a health department (74%) and operating during afternoon hours (66%). Men were more likely than women to prefer SSP in health departments (80% vs. 65%, p = 0.01), while more women than men preferred staffing by health department personnel (62% vs. 46%, p = 0.02). Women were less likely to favor evening hours (55% vs. 70%, p = 0.02). Fewer women wanted SSP nurses (78% vs. 90%, p = 0.01), social workers (11% vs. 24%, p = 0.01), or people who use drugs (20% vs 34%, p = 0.02) to staff SSP. Conclusions: Despite recent scale-up, SSP in Appalachia remain under-utilized. PWID were open to a range of options for SSP design and staffing, though there were variations by gender. Implementation research that identifies best strategies for tailored SSP scale-up in rural settings should be considered.

Feasibility and Validity of Geographically Explicit Ecological Momentary Assessment With Recall-Aided Space-Time Budgets.

We employ data from the Adolescent Health and Development in Context Study-a representative sample of urban youth ages 11-17 in and around the Columbus, OH area-to investigate the feasibility and validity of smartphone-based geographically explicit ecological momentary assessment (GEMA). Age, race, household income, familiarity with smartphones, and self-control were associated with missing global positioning systems (GPS) coverage, whereas school day was associated with discordance between percent of time at home based on GPS-only versus recall-aided space-time budget data. Fatigue from protocol compliance increases missing GPS across the week, which results in more discordance. Although some systematic differences were observed, these findings offer evidence that smartphone-based GEMA is a viable method for the collection of activity space data on urban youth.

Exposures to the tobacco retail environment among adolescent boys in urban and rural environments.

BACKGROUND: The tobacco industry spends billions on retail marketing and such marketing is associated with tobacco use. Previous research has not examined actual and potential exposures that adolescents have on a daily basis. OBJECTIVE: The objective of this study was to determine whether both self-reported and geographically estimated tobacco retailer exposures differ by participant or neighborhood characteristics among urban and rural adolescents. METHODS: The data for this study were part of a cohort study of 1220 adolescent males residing in urban and rural (Appalachian) regions in Ohio. The baseline survey asked participants how often they visited stores that typically sell tobacco in the past week (self-reported exposures). The number of tobacco retailers between home and school was determined using ArcGIS software (potential exposures). Adjusted regression models were fit to determine the characteristics that were associated with self-reported or potential exposures to retailers. RESULTS: Adolescents who were non-Hispanic black or other racial/ethnic minority, had used tobacco in the past, and lived in rural areas had higher self-reported exposures. Urban adolescents, non-Hispanic black or other racial/ethnic minority, and those living in neighborhoods with a higher percentage of poverty had more potential exposures to tobacco retailers in their path between home and school. CONCLUSIONS: Rural adolescents had more self-reported marketing exposures than urban adolescents. However, urban adolescents had more potential tobacco exposures between home and school. Thus, point of sale marketing limitations might be a more effective policy intervention in rural areas whereas limits on tobacco retailers might be more effective for urban areas.

Function of bacteriophage G7C esterase tailspike in host cell adsorption.

Bacteriophages recognize and bind to their hosts with the help of receptor-binding proteins (RBPs) that emanate from the phage particle in the form of fibers or tailspikes. RBPs show a great variability in their shapes, sizes, and location on the particle. Some RBPs are known to depolymerize surface polysaccharides of the host while others show no enzymatic activity. Here we report that both RBPs of podovirus G7C - tailspikes gp63.1 and gp66 - are essential for infection of its natural host bacterium E. coli 4s that populates the equine intestinal tract. We characterize the structure and function of gp63.1 and show that unlike any previously described RPB, gp63.1 deacetylates surface polysaccharides of E. coli 4s leaving the backbone of the polysaccharide intact. We demonstrate that gp63.1 and gp66 form a stable complex, in which the N-terminal part of gp66 serves as an attachment site for gp63.1 and anchors the gp63.1-gp66 complex to the G7C tail. The esterase domain of gp63.1 as well as domains mediating the gp63.1-gp66 interaction is widespread among all three families of tailed bacteriophages.

Ecological Networks and Community Attachment and Support Among Recently Resettled Refugees.

Interventions aimed at enhancing mental health are increasingly centered around promoting community attachment and support. However, few have examined and tested the specific ecological factors that give rise to these key community processes. Drawing from insights from the ecological network perspective, we tested whether spatial and social overlap in routine activity settings (e.g., work, school, childcare) with fellow ethnic community members is associated with individuals' attachment to their ethnic communities and access to social resources embedded in their communities. Data on routine activity locations drawn from the Refugee Well-Being Project (based in a city in the Southwestern United States) were used to reconstruct the ecological networks of recently resettled refugee communities, which were two-mode networks that comprise individuals and their routine activity locations. Results indicated that respondents' community attachment and support increased with their ecological network extensity-which taps the extent to which respondents share routine activity locations with other community members. Our study highlights a key ecological process that potentially enhances individuals' ethnic community attachment that extends beyond residential neighborhoods.

A social-contextual investigation of smoking among rural women: multi-level factors associated with smoking status and considerations for cessation.

INTRODUCTION: The social-contextual model of tobacco control and the potential mechanisms of the maintenance or cessation of smoking behavior among disadvantaged women, including rural residents, have yet to be comprehensively studied. The purpose of this study was to determine the association between selected individual, interpersonal, workplace, and neighborhood characteristics and smoking status among women in Appalachia, a US region whose residents experience a disproportionate prevalence of tobacco-related health disparities. These findings may assist in efforts to design and test scientifically valid tobacco control interventions for this and other disadvantaged populations. METHODS: Women, 18 years of age and older, residing in three rural Ohio Appalachian counties, were recruited using a two-phase address-based sampling methodology for a cross-sectional interview-administered survey between August 2012 and October 2013 (N=408). Multinomial logistic regression was employed to determine associations between select multilevel factors (independent variables) and smoking status (dependent variable). The sample included 82 (20.1%) current smokers, 92 (22.5%) former smokers, and 234 (57.4%) women reporting never smoking (mean age 51.7 years). RESULTS: In the final multivariable multinomial logistic regression model, controlling for all other significant associations, constructs at multiple social-contextual levels were associated with current versus either former or never smoking. At the individual level, for every additional year in age, the odds of being a former or never smoker increased by 7% and 6% (odds ratio (OR) (95% confidence interval(CI)): 1.07 (1.0-1.11) and 1.06 (1.02-1.09)), respectively, as compared to the odds of being a current smoker. With regard to depression, for each one unit increase in the Center for Epidemiologic Studies Depression Scale score, the odds of being a former or never smoker were 5% and 7% lower (OR(95%CI): 0.95(0.91-0.999) and 0.93(0.88-0.98)), respectively. Five interpersonal factors were associated with smoking status. As the social influence injunctive norm score increased by one unit, indicating perception of smoking to be more acceptable, the odds of being a former or never smoker decreased by 23% and 30%, respectively. For every one unit increase in the social participation score, indicating past-year engagement in one additional activity type, the odds of being a former or never smoker increased by 17% and 36%, respectively. For every 10% increase in the percentage of social ties in the participant's advice network who smoked, the odds of being a former or never smoker were 24% and 28% less, respectively. For every 0.1 unit increase in the E/I index, indicating increasing homophily on smoking in one's social network, the odds of being a former or never smoker were 20% and 24% less, respectively, in the time network, and 18% and 20% less, respectively, in the advice network. At the neighborhood level, for every one unit increase in neighborhood cohesion score, indicating increasing cohesion, the odds of being a former smoker or never smoker were 12% and 14% less, respectively. CONCLUSIONS: These findings indicate that a social-contextual approach to tobacco control may be useful for narrowing a widening trajectory of smoking disparity for rural women. Interpersonal context, in particular, must be considered in the development of culturally targeted cessation interventions for Ohio Appalachian women.

Tracking Young Adults' Attitudes Toward Tobacco Marketing Using Ecological Momentary Assessment (EMA).

BACKGROUND: Decades of research demonstrate the pernicious effects of targeted cigarette marketing on young people. Now, with tobacco marketing shifting toward greater incorporation of alternative products, it is critical to identify current attitudes toward the new landscape of tobacco advertisements. OBJECTIVES: The purpose of this study was to understand the present landscape of tobacco marketing to which young adults are exposed, and to assess how they respond to it. METHOD: During 2015-2016, we used ecological momentary assessment (EMA), in which 44 young adults (aged 18-28) carried smartphones equipped with a survey app. Seventy-seven percent were ever-users of tobacco and 29.5% were intermittent users of tobacco (someday users of cigarettes and/or those who used another tobacco product >5 times within the past year). For ten days, participants were prompted at three random times/day to complete a brief survey about their exposures and responses to tobacco-related advertising. Analyses used t-test and multilevel modeling. RESULTS: Intermittent users reported greater exposure than non-intermittent users to tobacco advertising. Further, both intermittent and ever-users reported more positive attitudes toward the tobacco advertising. Of the tobacco advertisements reported, 22% were for products unregulated by the FDA at the time of data collection. Conclusions/Importance: These findings indicate that young adults, and especially young adults who use tobacco, are exposed to a fair amount of tobacco advertising on a weekly basis. As the tobacco users in our sample were largely experimental and occasional users, these marketing exposures could put young adults at risk for progression toward regular use.

Ecological Networks and Urban Crime: The Structure of Shared Routine Activity Locations and Neighborhood-Level Informal Control Capacity.

Drawing on Jacobs (1961), we hypothesize that public contact among neighborhood residents while engaged in day-to-day routines, captured by the aggregate network structure of shared local exposure, is consequential for crime. Neighborhoods in which residents come into contact more extensively in the course of conventional routines will exhibit higher levels of public familiarity, trust, and collective efficacy with implications for the informal social control of crime. We employ the concept of ecological ("eco-") networks - networks linking households within neighborhoods through shared activity locations - to formalize the notion of overlapping routines. Using micro-simulations of household travel patterns to construct census tract-level eco-networks for Columbus, OH, we examine the hypothesis that eco-network intensity (the probability that households tied through one location in a neighborhood eco-network will also be tied through another visited location) is negatively associated with tract-level crime rates (N=192). Fitted spatial autoregressive models offer evidence that neighborhoods with higher intensity eco-networks exhibit lower levels of violent and property crime. In contrast, a higher prevalence of non-resident visitors to a given tract is positively associated with property crime. These analyses hold the potential to enrich insight into the ecological processes that shape variation in neighborhood crime.

Understanding Racial Differences in Exposure to Violent Areas: Integrating Survey, Smartphone, and Administrative Data Resources.

Emerging evidence indicates that exposure to violent areas may influence youth wellbeing. We employ smartphone GPS data on youth activity spaces to examine the extent of, and potential explanations for, racial disparities in these exposures. Multilevel models of data from the Adolescent Health and Development in Context study indicate that exposures to violent areas vary significantly across days of the week and between youth who reside in the same neighborhood. African American youth are exposed to areas with substantially higher levels of violence. Residing in a disadvantaged neighborhood is significantly associated with exposure to violent areas and explains a non-trivial proportion of the racial difference in this outcome. However, neighborhood factors are incomplete explanations of the racial disparity. Characteristics of the activity locations at which youth spend time explain the residual racial disparity in exposure to violent areas. These findings highlight the importance of youth activity spaces, above and beyond their neighborhood environments.

Empirical Reference Distributions for Networks of Different Size.

Network analysis has become an increasingly prevalent research tool across a vast range of scientific fields. Here, we focus on the particular issue of comparing network statistics, i.e. graph-level measures of network structural features, across multiple networks that differ in size. Although "normalized" versions of some network statistics exist, we demonstrate via simulation why direct comparison is often inappropriate. We consider normalizing network statistics relative to a simple fully parameterized reference distribution and demonstrate via simulation how this is an improvement over direct comparison, but still sometimes problematic. We propose a new adjustment method based on a reference distribution constructed as a mixture model of random graphs which reflect the dependence structure exhibited in the observed networks. We show that using simple Bernoulli models as mixture components in this reference distribution can provide adjusted network statistics that are relatively comparable across different network sizes but still describe interesting features of networks, and that this can be accomplished at relatively low computational expense. Finally, we apply this methodology to a collection of ecological networks derived from the Los Angeles Family and Neighborhood Survey activity location data.

The Role of Immigrant Concentration Within and Beyond Residential Neighborhoods in Adolescent Alcohol Use.

Neighborhoods are salient contexts for youth that shape adolescent development partly through informal social controls on their behavior. This research examines how immigrant concentration within and beyond the residential neighborhood influences adolescent alcohol use. Residential neighborhood immigrant concentration may lead to a cohesive, enclave-like community that protects against adolescent alcohol use. But heterogeneity in the immigrant concentrations characterizing the places residents visit as they engage in routine activities outside of the neighborhood where they live may weaken the social control benefits of the social ties and shared cultural orientations present in enclave communities. This study investigates whether the protective influence of residential neighborhood immigrant concentration on adolescent alcohol consumption diminishes when youth live in communities where residents collectively are exposed to areas with more diverse immigrant concentrations. This study tests this contention by analyzing survey and geographic routine activity space data from the Los Angeles Family and Neighborhood Survey, and the 2000 census. The sample includes 793 adolescents (48.7% female, 16.5% foreign-born Latino, 42.5% US-born Latino, 11.0% black, 30% white/other) between the ages of 12 and 17 who live in 65 neighborhoods in Los Angeles County. Immigrant concentration among these neighborhoods derives primarily from Latin America. The results from multilevel models show that immigrant concentration protects against adolescent alcohol use only when there is low neighborhood-level diversity of exposures to immigrant concentration among the contexts residents visit outside of their residential neighborhood. This research highlights the importance of considering the effects of aggregate exposures to non-home contexts on adolescent wellbeing.

Patterns of local segregation: Do they matter for neighborhood crime?

In this paper, we extend recent research on the spatial measurement of segregation and the spatial dynamics of urban crime by conceptualizing, measuring, and describing local segregation by race-ethnicity and economic status, and examining the linkages of these conditions with levels of neighborhood violent and property crime. The analyses are based on all 8895 census tracts within a sample of 86 large U.S. cities. We fit multilevel models of crime that incorporate measures of local segregation. The results reveal that, net of city-level and neighborhood characteristics, White-Black local segregation is associated with lower violent and property crime. In contrast, local segregation of low income from high income households is connected with higher crime, particularly neighborhood violence.