Measures Of Segregation Research Articles

In-situ measurement of diffusion and surface segregation of W and Ta in bare and W-coated EUROFER97 during thermal annealing

The near-surface composition of polished EUROFER97 samples was measured by Rutherford backscattering spectrometry while maintaining the analyzed surface at temperatures up to 1188 K. A sample pre-coated with less than a monolayer of tungsten by magnetron sputter deposition was included in the study. A shifting equilibrium due to diffusion and segregation of tungsten and tantalum was observed, with segregation being most important between 900 K and 1040 K, which is near the known transition temperature between the martensitic and austenitic phases. Diffusion counteracted any increase of the near-surface concentration of the elements of interest both above and below the temperature range in which segregation dominated. An asymmetry in the diffusion-segregation balance was observed when approaching the same temperature from above and below. The largest segregation peak measured at elevated temperature in this work indicated an increased amount of tungsten and/or tantalum near the sample surface with an areal atom density corresponding to 70–80% of a monolayer. Additional measurements were performed on bare EUROFER97 after annealing at 1089 K and 1553 K followed by rapid cooling to near room temperature which, if carried out at a critical rate, is expected to restore a martensitic microstructure. In the former case a similar enrichment peak was seen as that measured while the sample temperature was elevated, while in the latter case an increased concentration of tungsten and tantalum from 0.4 to 0.55 atomic percent in a layer of at least 300 nm thickness near the surface was observed.

Segregsmall: A command to estimate segregation in the presence of small units

Suppose that a population, composed of a minority and a majority group, is allocated into units, which can be neighborhoods, firms, classrooms, etc. Qualitatively, there is some segregation whenever allocation leads to the concentration of minority individuals in some units more than in others. Quantitative measures of segregation have struggled with the small-unit bias. When units contain few individuals, indices based on the minority shares in units are upward biased. For instance, they would point to a positive amount of segregation even when allocation is strictly random. The command segregsmall implements three recent methods correcting for such bias: the nonparametric, partial identification approach of D’Haultfœuille and Rathelot (2017, Quantitative Economics 8: 39–73); the parametric model of Rathelot (2012, Journal of Business & Economic Statistics 30: 546–553); and the linear correction of Carrington and Troske (1997, Journal of Business & Economic Statistics 15: 402–409). The package also allows for conditional analyses, namely, measures of segregation accounting for characteristics of the individuals or the units.

From residence to movement: The nature of racial segregation in everyday urban mobility

While research on racial segregation in cities has grown rapidly over the last several decades, its foundation remains the analysis of the neighbourhoods where people reside. However, contact between racial groups depends not merely on where people live, but also on where they travel over the course of everyday activities. To capture this reality, we propose a new measure of racial segregation – the segregated mobility index (SMI) – that captures the extent to which neighbourhoods of given racial compositions are connected to other types of neighbourhoods in equal measure. Based on hundreds of millions of geotagged tweets sent by over 375,000 Twitter users in the 50 largest US cities, we show that the SMI captures a distinct element of racial segregation, one that is related to, but not solely a function of, residential segregation. A city’s racial composition also matters; minority group threat, especially in cities with large Black populations and a troubled legacy of racial conflict, appears to depress movement across neighbourhoods in ways that produce previously undocumented forms of racial segregation. Our index, which could be constructed using other data sources, expands the possibilities for studying dynamic forms of racial segregation including their effects and shifts over time.

A Method for Studying Differences in Segregation Across Time and Space

An important topic in the study of segregation are comparisons across space and time. This article extends current approaches in segregation measurement by presenting a five-term decomposition procedure that can be used to understand more clearly why segregation has changed or differs between two comparison points. Two of the five terms account for differences in segregation that are due to the differing marginal distributions (e.g., the gender and occupational distributions), while one term accounts for differences in segregation due the different structure of segregation (what might be termed “pure” segregation). The decomposition thus presents a solution to the problem of margin dependency, frequently discussed in the segregation literature. Finally, two terms account for the appearance or disappearance of units when analyzing change over time. The method can be further extended to attribute structural changes to individual units, which makes it possible, for instance, to quantify the effect of each occupation on changing gender* segregation. The practical advantages of the decomposition are illustrated by two examples: a study of changing occupational gender segregation in the United States and a study of changing residential segregation in Brooklyn, New York.

Structural Racism and COVID-19 in the USA: a County-Level Empirical Analysis.

Substantial health disparities exist across race/ethnicity in the USA, with Black Americans often most affected. The current COVID-19 pandemic is no different. While there have been ample studies describing racial disparities in COVID-19 outcomes, relatively few have established an empirical link between these disparities and structural racism. Such empirical analyses are critically important to help defuse “victim-blaming” narratives about why minority communities have been badly hit by COVID-19. In this paper, we explore the empirical link between structural racism and disparities in county-level COVID-19 outcomes by county racial composition. Using negative binomial regression models, we examine how five measures of county-level residential segregation and racial disparities in socioeconomic outcomes as well as incarceration rates are associated with county-level COVID-19 outcomes. We find significant associations between higher levels of measured structural racism and higher rates of COVID-19 cases and deaths, even after adjusting for county-level population sociodemographic characteristics, measures of population health, access to healthcare, population density, and duration of the COVID-19 outbreak. One percentage point more Black residents predicted a 1.1% increase in county case rate. This association decreased to 0.4% when structural racism indicators were included in our model. Similarly, one percentage point more Black residents predicted a 1.8% increase in county death rates, which became non-significant after adjustment for structural racism. Our findings lend empirical support to the hypothesis that structural racism is an important driver of racial disparities in COVID-19 outcomes, and reinforce existing calls for action to address structural racism as a fundamental cause of health disparities.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40615-020-00948-8.

The role of racial segregation in treatment and outcomes among patients with hepatocellular carcinoma

BackgroundThere is a long history of segregation in the U.S.A with enduring impacts on cancer outcomes today. We evaluated the impact of segregation on racial disparities in Hepatocellular Carcinoma (HCC) treatment and outcomes. MethodsWe obtained data on black and white patients with HCC from the SEER program (2005–2015) within the 100 most populous participating counties. Our exposure was the index of dissimilarity (IoD), a validated measure of segregation. Outcomes were overall survival, advanced stage at diagnosis (Stage III/IV) and surgery for localized disease (Stage I/II). Cancer-specific survival was assessed using Kaplan–Meier estimates. ResultsBlack patients had a 1.18 times increased risk (95%CI 1.14,1.22) of presenting at advanced stage as compared to white patients and these disparities disappeared at low levels of segregation. In the highest quartile of IoD, black patients had a significantly lower survival than white (17 months vs 27 months, p < 0.001), and this difference disappeared at the lowest quartile of IoD. ConclusionsOur data illustrate that structural racism in the form racial segregation has a significant impact on racial disparities in the treatment of HCC. Urban and health policy changes can potentially reduce disparities in HCC outcomes.

Hospital transmission rates of the SARS-CoV 2 disease amongst orthopaedic in-patients in a secondary care centre: A quantitative review

IntroductionOrthopaedic practice changed during COVID-19 with elective work ceasing, trauma reducing and work forces redistributed to medical areas. During the United Kingdom lockdown, hospitals were stretched thinly with admissions of SARS-CoV-2 positive patients. AimEvaluate orthopaedic admissions to a district general hospital during lockdown and the volume of those who subsequently were found to be COVID-19 positive. MethodRetrospective study of patients admitted under trauma and orthopaedics between March 23, 2020–June 18, 2020. Data includes; diagnosis, COVID-19 swab dates, results and mortality using orthopaedic admission sheets, patient and pathology electronic recording system. Results3/4 of admitted patients tested negative for SARS-CoV-2 initially. Of these 240 patients, 12.5% subsequently tested positive during their stay, often within one week of their admission. 17.8% of patients were never tested. 7.8% mortality rate of which 48% were neck of femur fracture (NOF#) patients. 28 NOF# were confirmed COVID-19 positive; mortality rate of 21.4%. 87 NOF# were COVID-19 negative; mortality rate 6.9%. Mortality relative risk (RR) for NOF# and COVID-19 positive was 2.6. COVID-19 positive mortality 27% as compared to 4% in COVID-19 negative patients. Patients who acquired COVID-19 whilst in hospital had a mortality relative risk 6.4 Conclusion12.5% orthopaedic in-hospital viral transmission rate amongst orthopaedic patients despite the segregation measures taken, possibly due to asymptomatic health care workers or inpatients awaiting swab results. We emphasize the importance of testing all inpatients and regular testing of healthcare workers.

RECENT ADVANCES IN THE DIAGNOSIS AND CONTROL OF MAJOR DISEASES OF LIVESTOCK IN NIGERIA

For quicker and specific laboratory diagnosis there is a trend towards processing of specimens by sophisticated procedures like electron microscopy, immuno-electro-Osmo-phoresis, Fluorescent antibody and enzyme linked-immunosorbent tests. Specimens must, therefore, be collected as early as possible and transported on ice, without which the chances for diagnosis will be much reduced. Evolving disease resistant animals and birds has not met with success. The best means of preventing disease are by following strict measures of hygiene, sanitation, quarantine and segregation, including compulsory slaughter of the infected and the 'incontact animals'. When this is not possible, such as, for enzootic diseases and for those affecting many species of animals, vaccination is the only alternative. The quality of the vaccine and the manner in which it is administered will ultimately decide the outcome of immune response. Use of cell culture technology and genetic engineering have paved the way for modern technology of vaccine production. It is hoped that, in future, vaccines will be available to control diseases against which there are none at present.

Assessing the Relationship between Verbal and Nonverbal Cognitive Abilities Using Resting-State EEG Functional Connectivity.

The present study investigates the relationship between individual differences in verbal and non-verbal cognitive abilities and resting-state EEG network characteristics. We used a network neuroscience approach to analyze both large-scale topological characteristics of the whole brain as well as local brain network characteristics. The characteristic path length, modularity, and cluster coefficient for different EEG frequency bands (alpha, high and low; beta1 and beta2, and theta) were calculated to estimate large-scale topological integration and segregation properties of the brain networks. Betweenness centrality, nodal clustering coefficient, and local connectivity strength were calculated as local network characteristics. We showed that global network integration measures in the alpha band were positively correlated with non-verbal intelligence, especially with the more difficult part of the test (Raven’s total scores and E series), and the ability to operate with verbal information (the “Conclusions” verbal subtest). At the same time, individual differences in non-verbal intelligence (Raven’s total score and C series), and vocabulary subtest of the verbal intelligence tests, were negatively correlated with the network segregation measures. Our results show that resting-state EEG functional connectivity can reveal the functional architecture associated with an individual difference in cognitive performance.

All-cause mortality and three aspects of social relationships: an eight-year follow-up of older adults from one entire Korean village

Various aspects of social relationships have been examined as risk factors for mortality. In particular, most research has focused on either loneliness or social disengagement. We aimed to extend the current research by adding a group-level segregation measure utilizing the whole social network of one entire village in South Korea. The analyses were based on the Korean Social Life, Health and Aging Project data collected over eight years across five waves. Of the 679 old adults who participated throughout the entire project (to wave 5), 63 were confirmed as deceased. All three aspects of social relationships examined, loneliness, social disengagement, and group-level segregation, were associated with mortality in the traditional Cox proportional hazard model without considering health-related time-varying covariates. However, a Cox marginal structural model, a counterfactual statistical measure that is designed to control for censoring bias due to sample attrition over the eight years and time-varying confounding variables, revealed that only group-level segregation was associated with mortality. Our results strongly suggest that more attention is needed on group-level segregation for mortality studies, as well as on well-known individual-level risk factors, including social disengagement and loneliness. All methods were carried out in accordance with relevant guidelines and regulations.

Cortical processing of distracting speech in noisy auditory scenes depends on perceptual demand

Selective attention is essential for the processing of multi-speaker auditory scenes because they require the perceptual segregation of the relevant speech (“target”) from irrelevant speech (“distractors”). For simple sounds, it has been suggested that the processing of multiple distractor sounds depends on bottom-up factors affecting task performance. However, it remains unclear whether such dependency applies to naturalistic multi-speaker auditory scenes.In this study, we tested the hypothesis that increased perceptual demand (the processing requirement posed by the scene to separate the target speech) reduces the cortical processing of distractor speech thus decreasing their perceptual segregation. Human participants were presented with auditory scenes including three speakers and asked to selectively attend to one speaker while their EEG was acquired. The perceptual demand of this selective listening task was varied by introducing an auditory cue (interaural time differences, ITDs) for segregating the target from the distractor speakers, while acoustic differences between the distractors were matched in ITD and loudness. We obtained a quantitative measure of the cortical segregation of distractor speakers by assessing the difference in how accurately speech-envelope following EEG responses could be predicted by models of averaged distractor speech versus models of individual distractor speech. In agreement with our hypothesis, results show that interaural segregation cues led to improved behavioral word-recognition performance and stronger cortical segregation of the distractor speakers. The neural effect was strongest in the δ-band and at early delays (0 − 200 ms).Our results indicate that during low perceptual demand, the human cortex represents individual distractor speech signals as more segregated. This suggests that, in addition to purely acoustical properties, the cortical processing of distractor speakers depends on factors like perceptual demand.

Structural racism, socio-economic marginalization, and infant mortality

ObjectivesWe examine associations between infant mortality rates (IMRs) and measures of structural racism and socio-economic marginalization in Chicago, Illinois. Our purpose was to determine whether the Index of Concentration at the Extremes (ICE) was significantly related to community-level IMRs. Study designWe use a cross-sectional ecological public health design to examine community-level factors related to IMRs in Chicago neighborhoods. MethodsWe use data from the Chicago Department of Public Health and the American Community Survey to examine IMR inequities during the period 2012–2016. Calculations of the ICE for race and income were undertaken. In addition, we calculated racialized socio-economic status, which is the concentration of affluent Whites relative to poor Blacks in a community area. We present these ICE measures, as well as hardship, percent of births with inadequate prenatal care (PNC), and the percent of single-parent households as quintiles so that we can compare neighborhoods with the most disadvantage with neighborhoods with the least. Negative binomial regression was used to determine whether the ICE measures were independently related to community IMRs, net of hardship scores, PNC, and single-parent households. ResultsSpearman correlation results indicate significant associations in Chicago communities between measures of racial segregation and economic marginalization and IMRs. Community areas with the lowest ICERace scores (those with the largest concentrations of Black residents, compared with White) had IMRs that were 3.63 times higher than those communities with the largest concentrations of White residents. Most associations between community IMRS and measures of structural racism and socioeconomic marginalization are accounted for in fully adjusted negative binomial regression models. Only ICERace remained significantly related to IMRs. ConclusionsWe show that structural racism as represented by the ICE is independently related to IMRs in Chicago; community areas with the largest concentrations of Blacks residents compared with Whites are those with the highest IMRs. This relationship persists even after controlling for socio-economic marginalization, hardship, household composition/family support, and healthcare access. Interventions to improve birth outcomes must address structural determinants of health inequities.

Modeling the geospatial dynamics of residential segregation in three Canadian cities: An agent‐based approach

AbstractLong‐term residential segregation can exacerbate social inequality and exclusion in urban populations. Existing models of segregation aim to represent and better understand drivers of segregation and assess possible segregation effects in response to incoming immigrant populations. However, these studies are not typically implemented on real geospatial data to represent the urban environment, and even less frequently compare patterns of segregation between cities. Therefore, the objective of this study is to implement an agent‐based model that simulates the decision‐making process of immigrants as they arrive and settle in three Canadian gateways for immigration, including the City of Toronto, the City of Calgary, and Metro Vancouver. The resulting simulated spatial patterns of segregation are visually compared to real data representing the location of hotspots of immigrants of various ethnic origins. The degree of segregation is measured and compared, with measures of segregation obtained from actual census data. The spatial patterns and degree of segregation are compared across the three study areas. The developed model has the potential to be used as a tool for knowledge discovery and decision‐making in the processes of city planning.

Population Grids for Analysing Long-Term Change in Ethnic Diversity and Segregation

Changes in the spatial patterns of ethnic diversity and residential segregation are often highly localized, but inconsistencies in geographical data units across different time points limit their exploration. In this paper, we argue that, while they are often over-looked, population grids provide an effective means for the study of long-term fine-scale changes. Gridded data represent population structures: there are gaps where there are no people, and they are not (unlike standard zones) based on population distributions at any one time point. This paper uses an innovative resource, PopChange, which provides spatially fine-grained (1 km by 1 km) gridded data on country of birth (1971–2011) and ethnic group (1991–2011). These data enable insight into micro-level change across a long time period. Exploring forty years of change over five time points, measures of residential ethnic diversity and segregation are employed here to create a comprehensive ‘atlas’ of ethnic neighbourhood change across the whole of Britain. Four key messages are offered: (1) as Britain’s ethnic diversity has grown, the spatial complexity of this diversity has also increased, with greater diversity in previously less diverse spaces; (2) ethnic residential segregation has steadily declined at this micro-scale; (3) as neighbourhoods have become more diverse, they have become more spatially integrated; (4) across the whole study period, the most dynamic period of change was between 2001 and 2011. While concentrating on Britain as a case study, the paper explores the potential offered by gridded data, and the methods proposed to analyse them, for future allied studies within and outside this study area.

The impact of racial residential segregation on prostate cancer diagnosis and treatment.

To examine the effects of racial residential segregation and structural racism on the diagnosis, treatment, and outcomes of patients with prostate cancer. This retrospective cohort study examined men diagnosed with prostate cancer between 2005 and 2015. We collected data from Black and White men, aged ≥30years, living within the 100 most populous counties participating in the Surveillance, Epidemiology, and End Results programme, a nationally representative dataset. The racial Index of Dissimilarity, a validated measure of segregation, was the primary exposure of interest. Outcomes of interest included advanced stage at diagnosis (Stage IV), surgery for localised disease (Stage I-II), and 10-year overall and cancer-specific survival. Multivariable Poisson regression analyses with robust error variance estimated the relative risk (RR) of advanced stage at diagnosis and surgery for localised disease at differing levels of segregation. Survival analysis was performed using competing hazards analysis. Multivariable models estimating stage at diagnosis showed that the disparities between Black and White men disappeared at low levels of segregation. Disparities in receiving surgery for localised disease persisted across all levels of segregation. In racially stratified analyses, segregation had no effect on stage at diagnosis or surgical resection for Black patients. White patients saw a 56% (RR 0.42, P<0.001) reduced risk of presenting at advanced stage and 20% increased likelihood (RR 1.20, P<0.001) of surgery for localised disease. Black patients in the lowest segregation areas had the lowest overall mortality, but the highest cancer-specific mortality. Our study provides evidence that residential segregation has a significant impact on Black-White disparities in prostate cancer, likely through improved outcomes for White patients and worse outcomes for Black patients in more segregated areas. These findings suggest that mitigating segregation and the downstream effects of socioeconomic factors could alleviate these disparities.

Comparing ethnic segregation across cities\u2014measurement issues matter

This paper investigates how important measurement issues such as the modifiable areal unit problem (MAUP), random unevenness and spatial autocorrelation affect cross-sectional studies of ethnic segregation. We use geocoded data for German cities to investigate the impact of these measurement problems on the average level of segregation and on the ranking of cities. The findings on the average level of residential segregation turn out to be rather robust. The ranking of cities is, however, sensitive to the assumptions regarding reallocation of population across neighbourhoods that the use of different segregation measures involves. Moreover, the results suggest that standard aspatial approaches tend to underrate the degree of segregation because they ignore the spatial clustering of ethnic groups. In contrast, non-consideration of random unevenness gives rise to a moderate upward bias of the mean segregation level and involves minor changes in the ranking of cities if the minority group is large. However, the importance of random segregation significantly increases as the size of the minority group declines. If the size of specific ethnic groups differs across regions, this may also affect the ranking of regions. Thus, the necessity to properly account for measurement issues increases as segregation analyses become more detailed and consider specific (small) minority groups.

The Persistence of Residential Segregation by Race, 1940 to 2010: The Role of Federal Housing Policy

Has public policy shaped the persistence of residential segregation by race over time? Social Structures of Accumulation (SSA) theory, which explains major shifts in policy paradigms as a response to an economic crisis informs our analysis. We compare federal housing policy across two SSAs: the Keynesian period (1940–1970) characterized by welfare state expansion and the neoliberal period (1970–2010) marked by its contraction. Using the isolation index (a segregation measure), we track changes in the 20 Great Migration cities with the highest Southern-born Black population. Segregation rose steadily from 1940 to 1970s, plateaued at high levels from 1970 to 2010, but remained higher in 2010 than in 1940. Historical policy analysis reveals that regardless of the period, federal housing policy actively promoted residential segregation and underscores the urgency for social workers to mobilize for policy change.

Socioeconomic isolation and exposure to air toxics in the St. Louis metropolitan area, USA

Background: A growing body of research has examined the association between neighborhood residential segregation and exposure to hazardous air pollutants in the United States. However, few studies have incorporated neighborhood-level measures of segregation that account for contextual factors throughout an entire study area. We used spatial analyses to investigate the relationship between socioeconomic isolation and exposure to carcinogenic air toxics in the St. Louis metropolitan area. Methods: We developed spatial measures of neighborhood-level poverty isolation and neighborhood-level unemployment isolation. To construct these isolation measures, we obtained census tract-level sociodemographic data from the US Census Bureau. Air pollution data were obtained from the US Environmental Protection Agency and spatial analyses, conducted in ArcGIS, were used to identify air pollution hotspots. We used multivariable logistic regression to examine the association between poverty isolation, unemployment isolation, and exposure to air pollutants. Results: We identified four distinct air toxic hotspots in the St. Louis metropolitan area. Census tracts in the highest quartile of poverty isolation were eight times more likely to be located in an air toxic hotspot than tracts in the lowest quartile (95% Confidence Interval, 4.8-11.9). Census tracts in the highest quartile of unemployment isolation were three times more likely to be located in an air toxic hotspot than tracts in the lowest quartile (95% Confidence Interval, 1.9-4.6). Conclusions: Spatial analyses revealed that poor neighborhoods are disproportionately exposed to air pollutants. Despite improvements in US air quality since the 1970s, racial and economic disparities in exposure to hazardous air pollutants persist. Future investigations are warranted to identify sources of hazardous air pollutants and inform public health efforts to advance environmental justice.

Topological alterations in older adults with temporal lobe epilepsy are distinct from amnestic mild cognitive impairment.

Epilepsy incidence and prevalence peaks in older adults, yet systematic studies of brain aging and epilepsy remain limited. We investigated topological network disruption in older adults with temporal lobe epilepsy (TLE; age > 55years). Additionally, we examined the potential network disruption overlap between TLE and amnestic mild cognitive impairment (aMCI), the prodromal stage of Alzheimer disease. Measures of network integration ("global path efficiency") and segregation ("transitivity" and "modularity") were calculated from cortical thickness covariance from 73 TLE subjects, 79 aMCI subjects, and 70 healthy controls. Compared to controls, TLE patients demonstrated abnormal measures of segregation (increased transitivity and decreased modularity) and integration (decreased global path efficiency). aMCI patients also displayed increased transitivity and decreased global path efficiency, but these differences were less pronounced than in TLE. At the local level, TLE patients demonstrated decreased local path efficiency focused in the bilateral temporal lobes, whereas aMCI patients had a more frontal-parietal distribution. These results suggest that network disruption at the global and local level is present in both disorders, but global disruption may be a particularly salient feature in older adults with TLE. These findings motivate further research into whether these network changes have distinct cognitive correlates or are progressive in older adults with epilepsy.

Application of a new method for experimental validation of polydispersed DEM simulation of silo discharge

There are numerous experimentally validated simulations for mono-dispersed systems in the literature based on discrete element method (DEM). In practice, however, most of granular systems consist of polydispersed assemblies of particles. Few studies have considered the effect of polydispersity, and yet fewer have experimentally validated the results. In this study, application of a new experimental method for granular flow analysis is presented, capable of validating the results of an in-house developed GPU-based DEM solver in both monodispersed and polydispersed assemblies. Silo discharge is chosen as the case study in which discharge time, flow pattern and more importantly, the outlet composition variation with time (for polydispersed configurations) have been experimentally evaluated and validated with numerical results. The outlet composition, which is the ratio of fine to coarse particles in the outlet stream, is an essential measure of segregation in polydispersed silos, and its numerical prediction can be correct only if the interactions between fine and coarse particles within the silo are modelled precisely. Measuring this parameter is not possible using conventional experimental methods established in silo discharge studies such as high speed photographing or high-frequency weight measurement of the bed. A new apparatus has been developed which can measure this parameter. The device is a compartmented wheel rotating with a motor which gathers the outlet stream of the silo into different compartments. Due to practical limitations, design and function of the apparatus are not ideal. Forward mixing, distribution of particles with the same resident time in different compartments, is the most critical problem. Non-idealities must be compensated by means of post-processing codes so that comparable results are obtained from experiment and simulation.