912 resultados para segregation coefficient


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2000 Mathematics Subject Classification: Primary 30C45, secondary 30C80.

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In the paper the identification of the time-dependent blood perfusion coefficient is formulated as an inverse problem. The bio-heat conduction problem is transformed into the classical heat conduction problem. Then the transformed inverse problem is solved using the method of fundamental solutions together with the Tikhonov regularization. Some numerical results are presented in order to demonstrate the accuracy and the stability of the proposed meshless numerical algorithm.

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We measure the radial profile of the photoelastic coefficient C(r) in single-mode polymer optical fibers (POFs), and we determine the evolution of C(r) after annealing the fibers at temperatures from 40°C to 80°C. We demonstrate that C(r) in the fibers drawn from a preform without specific thermal pre-treatment changes and converges to values between 1.2 and 1.6×10-12 Pa-1 following annealing at 80°C. The annealed fibers display a smoothened radial profile of C(r) and a lowered residual birefringence. In contrast, the mean value of C(r) of the fiber drawn from a preform that has been pre-annealed remains constant after our annealing process and is significantly higher, i.e., 4×10-12 Pa-1. The annealing process decreases the residual birefringence to a lower extent as well. These measurements indicate the impact of annealing on the thermal stability of the photoelastic coefficient of POFs, which is an essential characteristic in view of developing POF-based thermomechanical sensors.

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Az ágazatok, foglalkozások, munkakörök nemek szerinti szegregációja a világ minden országára jellemző, jellegzetességei az eltérő gazdasági társadalmi, kulturális környezet ellenére gyakran nagyon hasonlítanak egymásra. Szakírók, politikai döntéshozók intézkedésekkel tartják javíthatónak a nők munkaerő-piaci pozícióját, a nemek közötti bérkülönbségek felszámolását. A követelmények és következtetések több szempontból sem helytállók. A nők és férfiak biológiai és társadalmi okokból eltérő kompetenciái, az ebből következő hatékonysági követelmények miatt a nemek szerinti elkülönülés a foglalkoztatás természetes következménye. Nem a szegregáció okozza a társadalmi egyenlőtlenségeket, hanem azok a munkaerő-piaci mechanizmusok, amelyek társadalmi hátránnyá formálják a foglalkozási struktúrában való elhelyezkedést. A beavatkozás csak ezeken keresztül lehetséges, ami azonban kockázatos, és amelynek tere meglehetősen szűk. A piaci erők önkényes korlátozása nem vezet a kívánatos eredményre, terelése csak egymással koherens társadalom-, népesség- és foglalkoztatási célrendszer megfogalmazása esetén lehet eredményes.

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In this paper, I explore socio-spatial segregation from a particular perspective, which may probably be considered a novelty in the investigation of spatial social patterns, as it focuses on questions such as: What kind of distinction occurs between socio-spatial patterns designated by statistical data and the cognitive representations of those patterns in people's minds? and What explains these diff erences, and what kind of impact can they generate?

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This paper examines the relationship between the historical development of residential segregation in Black areas of Dade County and the level of housing quality in those areas. Previous literature studies the effect of hypersegregation on housing quality. Instead, this paper analyzes the nature of each Black community and the social process by which they became segregated in contrast with only hypersegregation being considered. Data were drawn from the 1990 Census of Housing and Population at the block group level for Dade County. Two indicators for housing quality were considered: crowding and rent. Six categories for Black areas in Dade County and one residual category were developed for the analysis. Regression's results show that the effect of each community on housing quality varies. For example, overcrowding goes down in first-ghetto areas when compared to second-ghetto areas, although the percentage of Blacks in both communities is about the same. ^

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The present study examines the extent to which blacks are segregated in the suburban community of Coconut Grove, Florida. Hypersegregation, or the general tendency for blacks and whites to live apart, was examined in terms of four distinct dimensions: evenness, exposure, clustering, and concentration. Together, these dimensions define the geographic traits of the target area. Alone these indices can not capture the multi-dimensional levels of segregation and, therefore, by themselves underestimate the severity of segregation and isolation in this community. This study takes a contemporary view of segregation in a Dade County community to see if segregation is the catalyst to the sometime cited violent response of blacks. This study yields results that support the information in the literature review and the thesis research questions sections namely, that the blacks within the Grove do respond violently to the negative effects that racial segregation causes. This thesis is unique in two ways. It examines segregation in a suburban environment rather than an urban inner city, and it presents a responsive analysis of the individuals studied, rather than relying only on demographic and statistical data. ^

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This study explores the interaction of expatriates in Qatar and their perception of their subordination. The study design included participant observation in an all female University and University housing as well as interviews with Qatari government agencies and ministries, expatriate embassies and expatriates. Semi-structured interviews were conducted across seven expatriate groups: domestic workers, unskilled laborers, semiskilled, professionals, housewives, second-generation expatriates with host country other than Qatar, second-generation expatriates with host country Qatar, and Gulf Cooperation Council citizens. Forty-two subjects completed the interview schedule while 87 interviews were incomplete. ^ Physical control of expatriates occurs through the Gulf practice of sponsorship (The Kafeel System), and local cultural and Islamic related controls intertwined with the Arab Code of honor. Interviews and observations revealed rankings of Arabs and foreigners which emphasize Qatari superiority such as tribal identity, moral ranking of female groups by dress, legal protection and power, sexual consideration and desexualization and salaries and job opportunities based on nationality and ethnicity. Individuals who desire to transcend boundaries into the Qatari realm through citizenship or marriage view Qataris as possessing the “image of the unlimited good” and have acquired Qatari social and cultural capital. Members from all expatriate groups engaged in various forms of resistance to labor and gender domination which ranged from forms of “exit,” expressing a hidden transcript in the privacy of their own group, disguised resistance in public, and occasionally, direct confrontation with the Qatari. Although the legal arena created the appearance that worker's needs were being addressed, laborers engaged in forms of “exit” to escape their oppression. Omani students in the hostel disguised their resistance by spreading gossip, nick-naming homosexual Qatari students at the University, acting out a skit depicting their exclusion from Qatari privilege, spreading rumors of impending freedom, and singing songs of despair in the courtyard. Other sites of resistance were expatriate embassies, the road, the newspaper and technology. This study emphasizes that blaming oppression of the expatriate worker on globalization is a simplistic view of oppression in the Gulf, and ignores complex issues within Qatari society and other Gulf States. Sponsorship, servitude, and gender segregation intersect in Qatar to create a system of segregation and domination of expatriates. ^

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During the remediation of burial grounds at the US Department of Energy's (DOE's) Hanford Site in Washington State, the dispersion of contaminated soil particles and dust is an issue that is faced by site workers on a daily basis. This contamination problem is even more of a concern when one takes into account the semi-arid characteristics of the region where the site is located. To mitigate this problem, workers at the site use a variety of engineered methods to minimize the dispersion of contaminated soil and dust (i.e. use of water and/or suppression agents that stabilizes the soil prior to soil excavation, segregation, and removal activities). A primary contributor to the dispersion of contaminated soil and dust is wind soil erosion. The erosion process occurs when the wind speed exceeds a certain threshold value which depends on a number of factors including wind force loading, particle size, surface soil moisture, and the geometry of the soil. Thus under these circumstances, the mobility of contaminated soil and generation and dispersion of particulate matter are significantly influenced by these parameters. This dependence of soil and dust movement on threshold shear velocity, fixative dilution and/or application rates, soil moisture content, and soil geometry were studied for Hanford's sandy soil through a series of wind tunnel experiments, laboratory experiments and theoretical analysis. In addition, the behavior of plutonium (Pu) powder contamination in the soil was studied by introducing a Pu simulant (cerium oxide). The results showed that soil dispersion and PM10 concentrations decreased with increasing soil moisture. Also, it was shown that the mobility of the soil was affected by increasing wind velocity. It was demonstrated that the use of fixative products greatly decreased the amount of soil and PM10 concentrations when exposed to varying wind conditions. In addition, it was shown that geometry of the soil sample affected the velocity profile and calculation of roughness surface coefficient when comparing round and flat soil samples. Finally, threshold shear velocities were calculated for soil with flat surface and their dependency on surface soil moisture was demonstrated. A theoretical framework was developed to explain these dependencies.

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This paper examines the ways in which the legacy of school segregation in South Florida has affected the education of Haitian students and continues to limit their prospects. The high schools that serve neighborhoods with concentrated Haitian populations achieve shockingly poor academic results, which negatively affect Haitian student academic achievement.

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Variation in physical gradients and production along estuaries can alter species compositions. Spatiotemporal variation in abundance and distribution of palaemonid shrimp species was investigated in relation to seasonal freshwater inputs and salinity in the Shark River Estuary, Everglades National Park, Florida, USA. Using trapping techniques, multiple sites were sampled repeatedly extending from the headwaters to the Gulf of Mexico. Stable isotope analyses were also performed on a subset of samples. Five palaemonid species occurred in the samples: Palaemonetes paludosus (Gibbes, 1850), Palaemonetes pugio (Holthuis, 1949), Palaemonetes intermedius (Holthuis, 1949), Palaemon floridanus (Chace, 1942), and Leander paulensis(Ortmann, 1897). Overall, shrimp catches in traps doubled in the dry season. Catches in the upper estuary were dominated by P.paludosus, particularly in the wet season, while catch per unit effort at the most downstream and highest salinity sites were dominated by P. floridanus. At mid-estuary, several species co-occurred. δ15n analyses revealed that most species filled similar roles in the community, with the exception of P. paludosus, which shifted from enrichment in the dry season to depletion in the wet season as it expanded downstream in the estuary. Palaemonid δ13C values varied between sites and seasons, with shrimp in upstream sites being more depleted. These data suggest that changes in salinity regimes resulting from Everglades restoration efforts may result in species replacement, with potential implications for trophic dynamics.

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One of the most important goals of American educational institutions over the past 47 years has been the desegregation of pubic schools. This goal reflected the Supreme Court's decision in Brown v. Board of Education that segregated schools are inherently unequal and deny segregated minority students equal educational opportunities as mandated by the United States Constitution. This study examined the extent, nature, and causes of segregation in the Miami-Dade County Public Schools and the effects of segregation on the educational performance of minority students. ^ Research questions were analyzed using demographic data from the United States Census Bureau, the Metro-Dade County Planning Department, the United States Commission on Civil Rights, the United States Department of Education, and the Miami Dade County Public Schools. The extent of residential and school segregation in MiamiDade County was measured using the Dissimilarity Index. Historical and sociological literature were analyzed to explain the causes of school segregation, the socioeconomic characteristics of segregated minority students, and the relationship between school segregation and equal educational opportunities. A causal-comparative research method was chosen because it is the most appropriate method to compare the educational performance of minority students in segregated schools with the educational performance of minority students in desegregated schools. ^ The results of this study demonstrates that there is a high degree of residential and school segregation in Miami-Dade County, Florida. Furthermore, the Miami-Dade County Public Schools are characterized by a high degree of socioeconomic segregation. This is significant considering that the socioeconomic status of a student's peers is, after the student's family background, the most influential factor in determining academic performance. Clearly, schools and other social institutions must continue efforts to throughly desegregate the school district and improve minority student academic performance. A racially and economically desegregated school system would constitute an important component in Miami-Dade County's efforts to provide equal educational opportunities to all students. ^

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The Amazon savannas occur as isolated patches throughout extensive areas of forest in the states of Amapá, Amazonas, Pará, and Roraima. There is a considerable variation in the composition of anuran assemblages in the localities and phytophysiognomies of Amazon savannas and given the absence of studies on reproductive behavior, a systematic and geographically wide sampling has been carried out in the Amapá savanna, located in the Eastern Amazon. The study was conducted in a savanna area in the state of Amapá to examine the composition, ecology, and reproductive behavior of anuran amphibians. We carried out 24 field trips in each phytophysiognomy (gramineous-woody savana, gramineous-herbaceous-woody savana, park savana, and arboreal savanna); for analysis of reproductive behavior observations were made during the period January to December 2013, lasting four consecutive days. Samples were collected by active and acoustic search along 20 plots of 100x50 meters. Twenty-one anuran species were recorded, of which four are new records for the state of Amapá: Dendropsophus walfordi, Scinax fuscomarginatus, Pseudopaludicola boliviana e Elachistocleis helianneae. The KruskalWallis ANOVA revealed significant differences between richness and species diversity in the phytophysiognomies (p < 0.05). The Bray-Curtis similarity coefficient divided the phytophysiognomies into three groups: arboreal savana, gramineous-woody savanna and gramineous-herbaceous-woody savanna, and park savanna. According to the non-metric multidimensional scaling, the structure of the anuran community resulted in a separation into three phytophysiognomies, with significant differences in the structure of communities (ANOSIM, R = 0.823; p < 0.001). In the study of community ecology, the results obtained for spatial, temporal, and trophic niche breadth suggest that the assemblage of anurans of the Amapá savanna is not composed of predominantly generalist species. Also, the presence of other specialist anurans may explain the processes of speciation associated with the isolation of habitats, resulting in heterogeneity and spatial discontinuity in the phytophysiognomies with open formations. The null model analysis revealed that the community is structured based on temporal and trophic niche, indicating a significant influence of contemporary ecological factors on the assemblage. The absence of structure based on spatial niche might be explained by the spatial segregation in the distribution and occupation of anurans in the different phytophysiognomies of the Amapá savanna. Regarding the reproductive behavior of anurans, 11 species were classified as having a long breeding season, intrinsically associated with the rainy season and the reproductive mode of most species that lay egg clutches in lentic water bodies. Six reproductive modes were recorded and parental care was observed in Leptodactylus macrosternum and L. podicipinus, whose reproductive mode is characterized by foam nests. Regarding behavioral reproductive strategies, calling males were observed in all species of anurans, satellite males were recorded only for D. walfordi, Hypsiboas multifasciatus, S. nebulosus and S. fuscomarginatus; active search for females was observed for Phyllomedusa hypochondrialis and L. fuscus, and male displacement was recorded only for Rhinella major and R. margaritifera. Of the reproductive behaviors observed, throat and vocal sac display is associated with courtship and territorial behavior exhibited by males. In addition to courtship behavior, visual signals associated with courtship strategies were recorded for the anurans of the Amapá savanna.

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Date of Acceptance: 01/06/2015 We thank the University of Aberdeen for financial support and A.I. McNab (University of Aberdeen) for discussions involving the calculation of surface sites.