Study Of Segregation Research Articles

Correlation between prognostic chromosomal segregation and detected rearrangements in preimplantation embryos in a balanced translocation carrier

Introduction Individuals with balanced translocations are estimated to be around 1 % of the patients with infertility. A reciprocal translocation usually involves breakage of two non-homologous chromosomes with exchange of fragment with different size. The medical history of affected couples includes abortions, stillbirth, congenital anomalies, possible mental retardation and unsuccessful IVF attempts. It is hard to define the exact risk of unbalanced karyotypes in gametes, but it is accepted that it could be more than 80%. Preimplantation genetic screening (PGS) is strongly recommended in cases with chromosome rearrangements allowing the study of female gamete segregation. Material and Methods In the present case we performed two IVF-PGS cycles in a couple with a 34 years old woman with karyotype 46 XX, t(1;16)(q12;q13). Altogether, 14 embryos on day 3 where biopsied and tested using the 24sure (Illumina Inc., USA) protocol for BAC arrays. Results Out of the 14 tested embryos only two were euploid, five embryos had unbalanced genome due to the involvement of the chromosomes with the parental translocation. The other embryos had ‘sporadic'aneuploidy. After the PGS an embryotransfer of two euploid embryos was performed with one healthy baby born. Discussion Commonly more than 60 % of embryos obtained from patients with reciprocal translocations carry abnormal chromosomal constitution and about 1:28/30 are normal. In this case the percentage of unbalanced embryos - 5/14 (∼ 36 %) was significantly lower than the expected according to the published data. However, other independent aneuploidies also co-exist, most of which are age dependent. Conclusions The theoretical percentage of embryos with unbalanced karyotypes and the data from the clinical practice after performing PGS in IVF patients with balanced translocations does not match in every case. The phenomenon reveals the need of additional studies about the molecular mechanisms of chromosomal segregation in human gametes and preimplantation embryos delivered from balanced translocation carriers.

Social segregation of ecosystem services delivery in the San Antonio region, Texas, through 2050

Inequality in access to ecosystem services is inextricably linked with environmental justice in socially heterogeneous urban settings. Historically, San Antonio has been the gateway to Mexico and is strategically located along the North American Free Trade Agreement (NAFTA) corridor. It is also characterized by some of the most distinct residential segregation among U.S. cities. However, little is understood about the ways in which historically institutionalized residential segregation initiated by the Home Owners' Loan Corporation (HOLC) and NAFTA have affected socio-ecological outcomes. Here, this paper presents a novel empirical study of racial residential segregation. The study utilizes quantitative and spatially explicit estimates of regulating ecosystem services and biodiversity, and links the supply of ecosystem services to the distribution of human well-being within a heterogeneous social-ecological system. Specifically, the paper employed 1930s HOLC redlining maps and applied the ceteris paribus approach for racial concentrations to reflect a historical legacy and path dependence by institutional inertia. The results point to the social-ecological divide in that Hispanic and African American minorities derive fewer ecosystem benefits and face greater health risks and socio-economic disadvantages (p < 0.01). Notably, NAFTA corridor-related health risks are the most significant for the Hispanic population (p < 0.01). These patterns are likely to persist and may be amplified by 2050 (adjusted R2 = 0.646). The findings highlight that institutional transformations are essential for the greater social-ecological equity in the San Antonio region under NAFTA and, potentially, new United States-Mexico-Canada Agreement. Additionally, by assessing the EJ implications of spatially heterogeneous distribution of ecosystem services supply, the paper provides methodology that enhances science-based planning and better environmental decision-making to avoid or mitigate social-ecological divides in rapidly urbanizing regions both in the U.S. and around the world.

Entropic and Enthalpic Effects in Thin Film Blends of Homopolymers and Bottlebrush Polymers

We present a combined experimental and computational study of surface segregation in thin films of nearly athermal blends of linear and bottlebrush polymers. The lengths of bottlebrush backbone (Nb), bottlebrush side chain (Nsc), and linear polystyrene host (Nm) are systematically varied to examine the effects of polymer architecture on phase behavior. From the experiments, combinations of architectural parameters are identified that produce enrichment and depletion of bottlebrush at the polymer–air interface. These surface segregation behaviors are consistent with entropy-dominated thermodynamics. In addition, the experiments reveal conditions where bottlebrush and linear polymers are equally preferred at the surface. Simulations based on the self-consistent field theory (SCFT) qualitatively capture the three types of surface segregation behaviors and highlight the delicate interplay of entropic and enthalpic effects. Our investigations demonstrate that controlling both entropic and enthalpic driving for...

A multilevel structural equation modelling approach to study segregation of deprivation: an application to Bolivia

The study of segregation of deprivation can provide a tool to determine the economic, social and institutional factors associated with spatial unevenness in the distribution of wealth. Segregation is linked to social exclusion, diminished opportunities for human capital development and lower access to public services. In comparison to descriptive measures of poverty segregation, a multilevel structural equation modelling approach allows us to make statistical inferences about segregation, and to assess the extent to which segregation can be explained by contextual variables. Previous research using multilevel models to analyse segregation is extended to handle a continuous latent variable, measured by multiple binary indicators. The proposed approach is used to quantify the extent to which household deprivation is clustered within communities in Bolivia and to explore contextual factors associated with between-community differences in deprivation. Bolivia had one of the worst performances in poverty headcount ratio and chronic malnutrition in Latin America in the first decade of the twenty-first century, according to World Bank data. Bolivia is found to have a high level of segregation, since the main source of variation in deprivation arises from differences across communities, rather than within communities. Ethnicity, education, administrative region, distance to urban centres, and drought-induced migration significantly predict differences in the mean level of deprivation across Bolivian villages. This analysis helps to identify clusters of deprivation and highlights crucial sectors to be developed in order to reduce unevenness in the distribution of deprivation.

First-principles study of the solute segregation in twin boundaries in Mg and possible descriptors for mechanical properties

Twin boundaries play an important role in shaping the mechanical properties of Mg and Mg alloys. In this study, we simulate the segregation energies (SEs) of 23 solutes in the profuse {101¯2} and {101¯1} twin boundaries in Mg. Almost all solutes have both negative and positive SEs (except Tl), which indicate these solutes prefer to segregate at half of the sites in the twin boundaries. The correlation between the signs of SEs and the solute sites is a strong indication for the importance of the volumetric effects, which is confirmed by our modeling based on Voronoi volume calculations. In order to quantitatively describe the solute segregation, solute coverages of the two twin boundaries are calculated using the Langmuir-McLean model. Convergence tests are performed in order to obtain accurate solute coverages. The converged solute coverages are employed as descriptors for the solute strengthening through twin boundaries. Finally, we show two “treasure maps” for the materials design based on descriptors originated from solute solution effects at twin boundaries and stacking faults.

Building Inequality: Housing Segregation and Income Segregation

This article foregrounds housing in the study of residential segregation. The spatial configuration of housing determines the housing opportunities in each neighborhood, the backdrop against which households' resources, preferences, and constraints play out. I use census and American Community Survey data to provide the first evidence of the extent of housing segregation by type and by cost at multiple geographic scales in large metropolitan areas in the United States from 1990 to 2014. Segregation between single- and multifamily homes and renter- and owner-occupied homes increased in most metropolitan areas, whereas segregation by cost declined. Housing segregation varies among metropolitan areas, across geographic scales, and over time, with consequences for income segregation. Income segregation is markedly higher when and where housing segregation is greater. As long as housing opportunities remain segregated, residential segregation will change little, with urgent implications for urban and housing policy makers.

O pensamento sistêmico em análises urbanas: uma perspectiva para o problema da segregação socioespacial nas cidades

O presente artigo objetiva considerar a utilização da metodologia da abordagem sistêmica em análises urbanas, reconhecendo as cidades enquanto sistemas complexos passíveis de serem ordenados e equacionados na busca por soluções de problemas. Baseada nos conceitos da Teoria Geral dos Sistemas, a abordagem sistêmica é indicada, por vários autores, como um caminho metodológico adequado para integrar disciplinas na solução de um problema real. Para tal, deve-se ter um problema geral complexo que apresente elementos em incessante evolução e que esses possuam uma grande variedade de inter-relações. Visando a aplicação dessa metodologia, o estudo se volta à compreensão da segregação socioespacial enquanto parte integrante do macrossistema complexo das cidades sendo que, normalmente, essa temática é vista enquanto parte excluída desse sistema. Elabora-se uma proposta de pesquisa sistêmica orientada para a temática da segregação urbana. A pesquisa realizada possui natureza descritiva e exploratória a partir da análise de referenciais teóricos. Como resultado da pesquisa, conclui-se que a aplicação metodológica sistêmica em análises urbanas – sobretudo no estudo da segregação socioespacial – contribui de maneira satisfatória para a realização de diagnósticos urbanos. Constata- se também a premissa inicial de que a segregação pode ser analisada enquanto um sistema integrante do macrossistema das cidades.

Centrifugal casting of in-situ Al-Mg2Si(1-x)Snx composites: a study of radial segregation

ABSTRACTDuring centrifugal casting of Al-Mg2Si hypereutectic cylinders, the light Mg2Si particles are commonly segregated in centripetal direction towards the inner periphery. In order to change this inevitable centripetal segregation of Mg2Si particles, some amounts of tin up to 8 wt pct were added to Al-15wt.% Mg2Si alloy to enhance the formation of Mg2Si(1−x)Snx particles with variant stoichiometry thus variant density. XRD, EDS, optical metallography and hardness measurements were used to evaluate the stoichiometry and segregation patterns of in situ formed Mg2Si(1−x)Snx particles. According to the results, the cylinder containing 6 wt pct Sn illustrates a rather uniform distribution of particles thus hardness in all radial sections. However, the cylinders with higher amounts of Sn exhibit a radial segregation of Mg2Si(1−x)Snx particles in centrifugal direction towards the outer periphery. The results are interpreted in view of the Stokes’ law and the difference in density of the particles and the melt.

La situación de la mujer en los estudios de filosofía. Un análisis basado en indicadores

El artículo presenta un análisis, basado en indicadores, de la situación de la mujer en los estudios de filosofía y la carrera académica posterior. Aunque filosofía es agrupada, a efectos estadísticos, con las disciplinas de humanidades, que es un campo tradicionalmente considerado femenino, el trabajo muestra que los estudios de filosofía son un ámbito de conocimiento sumamente masculinizado. Los datos revelan: (1) que los estudiantes varones sobrepasan a las mujeres en 28 puntos porcentuales, (2) un porcentaje de profesorado femenino que apenas sobrepasa el 25% y (3) un techo de cristal reforzado con un 12% de catedráticas, frente al 21% de promedio en la universidad. En el artículo, se profundiza en el análisis de la segregación horizontal y vertical y se analiza la hipótesis FAB (field-specific ability belief). Esta hipótesis postula que las mujeres están infrarrepresentadas en aquellos campos, cuyos profesionales creen que el talento innato es el principal requerimiento para el éxito en su disciplina. El trabajo se enmarca en un proyecto más amplio, que busca mostrar que los agregados estadísticos usados en los estudios de segregación horizontal no son homogéneos, en lo que respecta a la presencia de la mujer, lo que en última instancia repercute en la efectividad de las medidas políticas que se toman.

Neutron reflectometry and hard X-ray photoelectron spectroscopy study of the vertical segregation of PCBM in organic solar cells

The composition of the active layer of a benchmark functional glass/ITO/[P3HT:PCBM][1.1:1]/Al organic solar cell has been studied by neutron reflectometry (NR) and hard X-ray photoelectron spectroscopy (HAXPES). Thermal annealing was performed in several steps and NR and HAXPES were recorded for every temperature. By fitting the NR results to a model composed of several layers, the scattering length density (SLD) distribution through the sample was obtained, and from this SLD profile, the evolution of the composition of the active layer as a function of temperature was established. For the outer layers, HAXPES results confirm the composition evolution. The results show that PCBM tends to segregate reducing the initial concentration of PCBM in the central part of the active layer and increasing its concentration towards both interfaces. The effect of the Al electrode as studied by HAXPES on the nearest zone of the active layer (up to 50 nm) is to stabilize the P3HT depletion in this area, an effect which is not affected by thermal annealing.

Theoretical study of fluorine-induced surface segregation of Cr in non-passivated Ni-based alloys

The effects of fluorine adsorption on the surface segregation behaviors of chromium in nickel-based alloys are systematically investigated by selecting three typical low-index Cr-doped Ni (111), (100), and (110) surfaces based on the first-principles calculations. The Cr doped in the nickel substrate is identified to possess a local trapping effect for fluorine in the full space and contributes to the more exothermic adsorption of fluorine. In turn, the chemisorption of fluorine on the Cr-doped Ni surfaces can dramatically incur the preferential top-surface segregation for Cr from nickel bulk. The increased adsorption energy of fluorine on Cr-doped Ni surfaces compensates for the larger surface energy of Cr relative to Ni. The strong F-Cr bonding from the deeper hybrid state of F 2p-Cr 3d helps to release strain energy caused by atomic size mismatch. At higher fluorine coverage, the driving force for Cr to segregate at nickel surfaces is significantly increased, as the fluorine starts to agglomerate in the vicinity of Cr. Such chemisorption-induced surface abnormal segregation of Cr to the top-most surface plays a critical role in the preferential dealloying of Cr at the early-stage corrosion of non-passivated nickel-based alloys in molten fluoride salts.

Visual and Microscopic Evaluation of &lt;em&gt;Streptomyces&lt;/em&gt; Developmental Mutants

Streptomycetes are filamentous soil bacteria belonging to the phylum Actinobacteria that are found throughout the world and produce a wide array of antibiotics and other secondary metabolites. Streptomyces coelicolor is a well-characterized, non-pathogenic species that is amenable to a variety of analyses in the lab. The phenotyping methods described here use S. coelicolor as a model streptomycete; however, the methods are applicable to all members of this large genus as well as some closely related actinomycetes. Phenotyping is necessary to characterize new species of Streptomyces identified in the environment, and it is also a vital first step in characterizing newly isolated mutant strains of Streptomyces. Proficiency in phenotyping is important for the many new researchers who are entering the field of Streptomyces research, which includes the study of bacterial development, cell division, chromosome segregation, and second messenger signaling. The recent crowdsourcing of antibiotic discovery through the isolation of new soil microbes has resulted in an increased need for training in phenotyping for instructors new to the field of Streptomyces research and their college or high school students. This manuscript describes methods for bacterial strain propagation, storage, and characterization through visual and microscopic examination. After reading this article, new researchers (microbiology education laboratories and citizen scientists) should be able to manipulate Streptomyces strains and begin visual characterization experiments.

Visual and Microscopic Evaluation of Streptomyces Developmental Mutants.

Streptomycetes are filamentous soil bacteria belonging to the phylum Actinobacteria that are found throughout the world and produce a wide array of antibiotics and other secondary metabolites. Streptomyces coelicolor is a well-characterized, non-pathogenic species that is amenable to a variety of analyses in the lab. The phenotyping methods described here use S. coelicolor as a model streptomycete; however, the methods are applicable to all members of this large genus as well as some closely related actinomycetes. Phenotyping is necessary to characterize new species of Streptomyces identified in the environment, and it is also a vital first step in characterizing newly isolated mutant strains of Streptomyces. Proficiency in phenotyping is important for the many new researchers who are entering the field of Streptomyces research, which includes the study of bacterial development, cell division, chromosome segregation, and second messenger signaling. The recent crowdsourcing of antibiotic discovery through the isolation of new soil microbes has resulted in an increased need for training in phenotyping for instructors new to the field of Streptomyces research and their college or high school students. This manuscript describes methods for bacterial strain propagation, storage, and characterization through visual and microscopic examination. After reading this article, new researchers (microbiology education laboratories and citizen scientists) should be able to manipulate Streptomyces strains and begin visual characterization experiments.

Modelling residential segregation as unevenness and clustering: A multilevel modelling approach incorporating spatial dependence and tackling the MAUP

Traditional studies of residential segregation use a descriptive index approach with predefined spatial units to report the degree of neighbourhood differentiation. We develop a model-based approach which explicitly includes spatial effects at multiple scales, recognising the complexity of the urban environment while simultaneously distinguishing segregation at each scale net of all other scales. Moreover, this model distinguishes segregation as unevenness and as spatial clustering in the presence of stochastic variation. The modelling approach, unlike traditional index approaches, allows hypothesis evaluation concerning alternative scales and zonation through an accompanying badness-of-fit measure. Ultimately, this permits the identification of the scale and zonation regime where the spatial patterns come into focus thereby directly tackling the modifiable areal unit problem. The model is applied to Indian ethnicity in Leicester, UK, finding segregation as unevenness and as spatial clustering at multiple scales.

Problem of attaining constant impurity concentration over ingot height

The possibility of growing crystals with homogeneous impurity distribution over crystal height has been demonstrated in a study of segregation during silicon and germanium growth from thin melt layers using the submerged heater method. Numeric simulation of 200 mm diam. antimony-doped germanium crystallization has shown that, beginning from a 40 mm melt layer thickness, the exact problem solution with convection allowance is identical to the unidimensional heat exchange problem solution in the central ingot part. The conditions under which convection can be ignored in mass transport calculation are more rigorous: the melt layer height must be within 20 mm. In this case Tiller’s ratio can be used for calculating the longitudinal impurity distribution for predominantly diffusion-controlled mass transport pattern. Analysis of the existing attempts to describe the experimental crystal growth results using the simplified formulae shows that they only yield acceptable results if the actual growth rate or change in melt layer thickness during crystallization are taken into account, e.g. as in the formula suggested by Marchenko et al. One can therefore analytically describe the longitudinal impurity distribution in the ingot, e.g. B and P distribution in silicon, and recommend the degree of additional doping of the melt zone under the heater so that to provide a constant impurity concentration over the ingot height. Homogeneous material can be obtained after residual layer solidification in the end portion of the ingot if the growth rate is controlled through varying the cooling rate.

공직부처의 성별직무분리에 관한 탐색적 분석: 단순한 차이인가? 의도적 차별인가?

본 연구가 다루고자 하는 주제는 현재 우리나라 공직부처 일선에서 근무하는 공무원의 성별직무분리 현상을 탐색하고, 그 결과를 시론적으로 분석해 보는 것이다. 현재 우리나라 공직의 인사정책이나 양성평등정책에 있어서 성별직무분리에 의한 설명은 다소 결여되어 있는 상태이며, 관련 연구도 미흡한 편이다. 그럼에도 불구하고 성별직무분리의 가설은 공직의 상당수 직무들이 여성직 혹은 남성직으로 분리되어 있음을 일상에서 흔히 관찰할 수 있다는 사실에 근거한다. 또한 성별직무분리 현상은 남녀가 같은 사무실이나 업무공간에 섞여서 일상적으로 일을 하고 있다 하더라도, 그들이 가진 직무의 명칭이 다른 경우가 많다는 점에 근거한다. 그래서 이 개념은 남녀가 같은 공간에서 함께 일하고 있는 사실과는 별로 관계가 없다. 본 연구는 일단 우리나라 공직의 성별직무분리 여부를 계량적으로 가늠해 보고자 했다. 탐색적인 분석을 위해서는 역대 정부의 정부기능분류체계(BRM)에 기반한 장기 인사데이터에 대한 상이성 지수를 이용하여 측정하였다. 그 결과, 공직에서 여성은 남성에 비해 특정부처와 직무로의 쏠림 현상이 장기적으로 일어나고 있었다. 그리고 공직에서 조직의 규모가 클수록 성별직무분리 현상이 심화되는 경향이 있었으며, 최근으로 올수록 성별직무분리가 부처별로 더 심해지고 있다는 점이 특징적이었다. 이는 남녀간 성별 직무가 단순한 차이의 수준을 넘어설 개연성을 보여주었다. 나아가 공직인사에서 양성평등이나 성별 격차의 개선정책을 추진함에 있어 일정한 한계가 있었다는 점을 지적하는 동시에 향후 관련연구 및 인사관리에 의미 있는 시사점도 제시해 주었다.

The Shortest Path Isolation Index: A New Measure for Individual-level Residential Segregation

The study of segregation is essential for understanding how place influences life outcomes. Traditional segregation indices rely heavily on the use of areal units for calculation, which risks introducing both measurement and interpretation error. Using individual-level data avoids many of the problems facing traditional area-level indices. However, few segregation indices currently exist that are capable of utilizing such data. Given that our understanding is only as good as our measurement, it is imperative that our measures accurately reflect our perceptions of segregation. Utilizing the recent release of the complete 1940 Census count data, this article details a new individual-level segregation measure—the shortest path isolation (SPI) index. The SPI index captures the degree of racial isolation experienced by an individual, regarding both distance and interpersonal contact. With West Philadelphia as a sample study area, this article highlights the benefits of the SPI index for studying segregation at the individual level.

Cultural stereotypes and professional self-socialisation in the transition from education to work

A key insight from studies of gender segregation is that the allocation of different groups to different positions in the labour market is strongly related to ascribed status. Shared gendered cultural beliefs generally portray men as more competent and of a higher status than women, and position some workers as more suited than others to perform different types of work and tasks. Yet, although much work has been done on status and gender segregation, this research tends to overlook the intersections of gender, race, and ethnicity. This study contributes to the literature by examining how skills and competence are valued in traditionally gender- segregated professions that have seen an increased influx of immigrants and ethnic minorities. Drawing on 66 qualitative interviews with Norwegian students, the study analyses, first, how gender, racial, and ethnic stereotyping of tasks and competencies affect the students’ aspirations in transition from education to work, and second, how the intersection between race, ethnicity, and gender plays out quite differently in different professions. Theoretically, I develop the concept of ‘professional self-socialisation’, which points to the process whereby individuals adapt and redefine their aspirations to the gendered, ethnic, and racial hierarchy of suitability within their profession.

First-principles study of hydrogen segregation at the MgZn2 precipitate in Al-Mg-Zn alloys

Hydrogen embrittlement susceptibility of high strength 7xxx series Al alloys has been recognized as the critical issues in the practical use of Al alloys. In spite of the recent improvement of experimental technique, the hydrogen distribution in Al alloys is still unclear. Focusing on the interface between MgZn2 precipitates and an Al matrix, which is considered as one of the important segregation sites in these alloys, we investigated the stable η-MgZn2–Al interface, and the possible hydrogen trap sites in MgZn2 and at the η-MgZn2–Al interface via first-principles calculation. Most of the interstitial sites inside the MgZn2 crystal were not possible trap sites because their energy is relatively higher than that of other trap sites. The trap energy of the most favorable site at the η-MgZn2–Al is approximately −0.3 eV/H, which is more stable that of the interstitial site at the grain boundary. The interface between MgZn2 and Al is likely to be a possible trap site in Al alloys. Moreover, hydrogen atoms do not tend to be trapped around Zn, but a trap site around Mg is favorable; this observation is consistent with previous experimental observations.

“Race and Housing Values: What Happens When Whites Don't All Move Out?”

Previous research on neighborhood racial composition and housing values has demonstrated that as the proportion of Black residents in a neighborhood increases housing values lag. In this paper, we investigate whether there are neighborhood types or locations where racial diversity does not have a negative impact on housing values. This research contributes to the study of residential segregation by focusing on stable integrated neighborhoods. Using metropolitan Philadelphia as a strategic case, we compare stable, integrated neighborhoods to racially transitioning neighborhoods and predominantly White and Black neighborhoods. To do this, we comparatively examine housing prices and rates of home value appreciation from 1990 to 2005. We find that stable integrated neighborhoods have rates of appreciation slightly higher than predominantly White neighborhoods.