Desegregating health statistics: what should be done?
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The relation between popularity and achievement: a longitudinal test of the lateral transmission of value hypothesis.
Data from a longitudinal study of school desegregation were used to examine the relation between normative social influence processes and academic achievement in order to test theoretical models of how school desegregation produces benefit. Subjects were white, Mexican-American, and black elementary school children who were measured once prior to and twice after desegregation of their schools. For all groups, analyses using structural equation techniques showed that, contrary to the lateral transmission of values hypothesis, which views social influence processes as shaping academic achievement, "causal influence" did not flow from social acceptance to academic achievement; instead, achievement appeared to affect subsequent social acceptance.
Achievement↗
Justice deferred a half century after Brown v. Board of Education.
The road to Brown v. Board of Education (1954) was a slow and circuitous climb, whereas the retreat down from Brown has been swift and direct. This article reviews 4 distinct U.S. Supreme Court eras of racial decisions: the segregation, preparatory, desegregation, and resegregation eras. It notes both the strengths and weaknesses of Brown and discusses the effects of school desegregation. Did racial diversity improve the life chances of African American children as intended? The results of longitudinal research demonstrate that the effects have been positive, although these results are not widely known by the American public. The article challenges this and other misconceptions about school desegregation that have become entrenched in the public's thinking and addresses ways to rekindle the spirit of Brown.
Black People↗
Beyond the optimal contact strategy: a reality check for the contact hypothesis.
The contact hypothesis proposes that interaction between members of different groups reduces intergroup prejudice if--and only if--certain optimal conditions are present. For over 50 years, research using this framework has explored the boundary conditions for ideal contact and has guided interventions to promote desegregation. Although supporting the contact hypothesis in principle, the authors critique some research practices that have come to dominate the field: (a) the prioritizing of the study of interactions occurring under rarefied conditions, (b) the reformulation of lay understandings of contact in terms of a generic typology of ideal dimensions, and (c) the use of shifts in personal prejudice as the primary measure of outcome. The authors argue that these practices have limited the contact hypothesis both as an explanation of the intergroup dynamics of desegregation and as a framework for promoting social psychological change. In so arguing, the authors look toward a complementary program of research on contact and desegregation.
Group Processes↗
Failure to maintain eye-specific segregation in nob, a mutant with abnormally patterned retinal activity.
Axon terminals from the two eyes initially overlap in the dorsal-lateral geniculate nucleus (dLGN) but subsequently refine to occupy nonoverlapping territories. Retinal activity is required to establish and maintain this segregation. We show that despite the presence of retinal activity, segregated projections desegregate when the structure of activity is altered. Early in development, spontaneous retinal activity in the no b-wave (nob) mouse is indistinguishable from that of wild-type mice, and eye-specific segregation proceeds normally. But, around eye-opening, spontaneous and visually evoked activity in nob retinas become abnormal, coincident with a failure to preserve precise eye-specific territories. Dark-rearing studies suggest that altered visual experience is not responsible. Transgenic rescue of the mutated protein (nyctalopin) within nob retinal interneurons, without rescuing expression in either retinal projection neurons or their postsynaptic targets in the dLGN, restores spontaneous retinal activity patterns and prevents desegregation. Thus, normally structured spontaneous retinal activity stabilizes newly refined retinogeniculate circuitry.
Animals↗
Ethnicity as a mediating variable of early adolescent identity development.
The variables of race/ethnicity, sex and grade were examined as potential mediating factors of early adolescent identity development. The EOM-EIS was administered to 367 middle-school students in an urban southwestern setting. Results provided evidence that the EOM-EIS is an appropriate instrument for use with this age sample. Additionally, females and older students were found to be more developmentally sophisticated than other groups. Finally, ethnic minorities were found to be significantly more foreclosed than their non-minority counterparts. As the school was a mandatory desegregation site, implications of school desegregation were discussed.
Adolescent↗
The power of the Brown v. Board of Education decision: theorizing threats to sustainability.
Interviews with African American and White American elders capture the immediate power of the Brown v. Board of Education (1954) decision and the biography of its impact over time. This article reviews the lived experience of the decision and theorizes 3 threats to sustainability that ruthlessly undermined the decision over time: (a) the unacknowledged and enormous sacrifice endured by the African American community in the name of desegregation; b) the violent and relentless resistance to the decision by government officials, educators, and many White community members; and (c) the dramatic shrinkage of the vision of Brown from the dismantling of White supremacy to a technical matter of busing. Implications are drawn for the study of desegregation and for the study of sustainability of social justice more broadly.
Black People↗
Opportunities and constraints: black-white differences in the formation of interracial friendships.
In this article, we examine the effects of classroom characteristics on the interracial friendliness of students in desegregated classrooms. We argue that social psychological processes that affect cross-race sociability are set in motion by the classroom climate, the organization of instruction, and the class racial composition. The effects of these variables on the likelihood of cross-race friendships are observed in longitudinal data from 455 students in 16 fourth- through seventh-grade desegregated classrooms. The results show that classroom characteristics associated with "status-leveling" effects operate differently for black and white students. Ability grouping influences the interracial sociability of white students more than that of blacks, while the academic status of peers affects the cross-race friendships of blacks more than of whites. Race differences in the effects of classroom climate on interracial friendships are also observed.
Achievement↗
How low can it go? Declining black-white segregation in a multiethnic context.
We extend research on whites' neighborhood contact with blacks, population composition, and prospects for desegregation by developing a new measure of the floor of racial residential segregation under conditions of low black-white contact. The measure incorporates the way in which multiethnic contexts further constrain levels of black-white segregation. The results show that black-white desegregation is likely when the black population is small, but is unlikely otherwise. Yet, when multiple ethnic groups are sufficiently large, a moderate level of black-white segregation is necessary for whites to maintain low neighborhood contact with blacks, even when the proportion of African Americans is small.
Black or African American↗
NMDA receptor agonist and antagonists alter retinal ganglion cell arbor structure in the developing frog retinotectal projection.
The development of sensory maps is thought to require an activity-dependent structural rearrangement of afferent terminal arbors within the CNS which recreates the topographic relations of sensory somata present in the periphery. In the frog retinotectal projection, activation of the NMDA receptor plays a role in this structural plasticity. Exposure of the optic tectum of tadpoles to NMDA receptor antagonists results in a rearrangement of retinal ganglion cell arbors so that their organization into a topographic projection and eye-specific stripes is disrupted (Cline et al., 1987; Cline and Constantine-Paton, 1989). Exposure of the optic tectum to the receptor agonist, NMDA, increases the eye-specific segregation of these arbors (Cline et al., 1987). We examined the projection of the supernumerary retina and the morphology of individual retinal afferent arbors of untreated, NMDA-treated, APV-treated, MK801-treated, and MK801/NMDA-treated 3-eyed tadpoles and young postmetamorphic frogs in an effort to understand how NMDA receptor activation is involved in the growth and ordering of retinal arbors. Treatments with MK801 in combination with NMDA resulted in a desegregation of eye-specific stripes, whereas treatments with MK801 or NMDA alone did not. As reported previously, APV treatment resulted in stripe desegregation without increasing the tangential area (measured from 2-dimensional drawings) of the terminal arbors. However, a detailed analysis revealed that the APV-treated tadpole arbors have 35% reduction in branch density (branch tips/area) compared to untreated 3-eyed tadpole arbors. We treated the optic tectum with a range of concentrations of NMDA prepared in the slow-release plastic Elvax. NMDA at 10(-4) M in Elvax was the optimal concentration to produce the sharpening of stripe borders. Exposure of the tectum to NMDA at 10(-6) M in Elvax produced no change in the stripe pattern, while 10(-2) M NMDA in Elvax resulted in beading of the arbors. At the optimal concentration NMDA treatment results in a 75% reduction in the number of axons crossing from a stripe to an interstripe zone. Drawings of individual HRP-labeled, NMDA-treated arbors demonstrate that they have fewer branch points and fewer branch tips. NMDA treatment reduced arbor density by approximately 50%. Arbors drawn from untreated postmetamorphic frogs have twice the branch density of arbors from untreated tadpoles. NMDA treatment in these animals reduced the branch density by 55%, comparable to the reduction seen in tadpole branch density. Our data support a specific hypothesis for NMDA receptor involvement in the activity-dependent structural refinement process within the developing retinotectal projection.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Inez Beverly Prosser and the education of African Americans.
Inez Beverly Prosser (ca. 1895-1934) was arguably the first African American woman to earn a doctorate in psychology. Her dissertation, completed in 1933, examined personality differences in black children attending either voluntarily segregated or integrated schools and concluded that black children were better served in segregated schools. This research was one of several studies in the 1920s and 1930s that was part of the debate on segregated schools as maintained in the United States under the "separate but equal" doctrine of Plessy v. Ferguson (1896). This article examines the life and career of Prosser in the context of educational barriers and opportunities for African Americans in the early part of the twentieth century and explores the arguments that pitted African Americans against one another in determining how best to educate black children, arguments that eventually led to the desegregation decision of Brown v. Board of Education (1954).
Black or African American↗
Competitive segregation of Si and P on Fe(96.5)Si(3.5) (100) and (110).
Annealing an Fe(96.5)Si(3.5) (100)/(110) bicrystal, containing 90 ppm P, leads immediately to a strong segregation of silicon. The Si atoms, however, desegregate subsequently and are displaced by P, whose segregation enthalpy is larger than that of silicon. The corresponding surface structures formed on both faces have been studied using complementary methods: Scanning tunneling microscopy (STM) to obtain atomically resolved geometrical information and Auger electron spectroscopy (AES) for the determination of the surface composition. Si substitutes surface Fe atoms on both faces and forms ordered surface alloys, whereas P occupies hollow sites on the surface. Si and P form c(2 x 2) superstructures on the (100) surface, whereby each segregated phosphorus atom blocks in the average one silicon segregation site. The (110) surface, on the other hand, is characterized by a c(1 x 3) Si superstructure. Due to the anisotropy of this surface the P/Si exchange proceeds by the formation of silicon coverage decreasing domain boundaries within the silicon structure, which are simultaneously occupied by P atoms. Furthermore the comparison of the AES and STM derived phosphorus coverages indicates a P multilayer segregation on the (110) surface.
Journal Article↗
A mathematical model of activity-dependent, anatomical segregation induced by competition for neurotrophic support.
Mathematical or computational models of activity-dependent neural competition typically impose competition in anatomically fixed networks by the use of synaptic normalisation, for which there is very little experimental support. Recent experimental evidence, however, strongly implicates neurotrophic factors in neural plasticity and competition, in addition to their well-known potent effects on neurite outgrowth and synaptogenesis. We therefore present a simple, mathematical model of anatomical segregation induces by activity-dependent competition for a limited supply of a neurotrophic factor provided by target cells to afferents. We extract the behaviour of the model in various regimes, in which the neurotrophic factor is either in critical supply or in abundant supply, by a combination of analytical and numerical methods, and study the effects of correlations in afferent inputs on competition. We apply the model to three different systems: ocular dominance column formation; elimination of polyneuronal innervation at the vertebrate neuromuscular junction; trigeminal brain stem whisker-related structure formation. Several classes of related predictions emerge, including the prediction that kittens reared with strabismus should require a higher concentration of neurotrophic factor infusion into their primary visual cortex than normally reared cats in order to induce the anatomical desegregation of ocular dominance columns. We also speculate on the mechanisms of support of inhibitory rather than excitatory neurons, and suggest the existence of a separate, (Cl-)-mediated activity-dependent pathway for their neurotrophic support.
Animals↗
Differential expression of nitric oxide synthases in EGF-responsive mouse neural precursor cells.
Nitric oxide (NO) is a gaseous, radical molecule that plays a role in various physiological processes in the nervous system such as learning and hippocampal plasticity. It is generated from l-arginine by nitric oxide synthases (NOS), which come in three isoforms depending on the tissue of origin, namely inducible-NOS (iNOS in macrophages), endothelial-NOS (eNOS in endothelial cells) and neural-NOS (nNOS in neural cells). We used epidermal growth factor (EGF)-responsive nestin-positive neural precursor cells originating from the mouse E16 embryonic striatum, and studied the relative expression of NOS isoforms probed with isoform-specific antibody using the avidin-biotin immunohistochemical method. Our data revealed both nNOS and eNOS to be expressed in both neurospheres and desegregated neural precursor cells. However, iNOS signals were virtually undetectable in both cell categories. When the neural precursor cells were carried in the presence of poly-l-ornithine (PLO), there was a strong induction of the expression of iNOS proteins, indicating the possibility that this isoform is amenable to modulation by extracellular cues. These preliminary results suggest both nNOS and eNOS to be important in the physiology of neural precursor cells, and that iNOS might also play a role at certain stages in the life of these cells.
Animals↗
The differential influence of protein kinase inhibitors on retinal arbor morphology and eye-specific stripes in the frog retinotectal system.
We investigated retinal axon morphology and eye-specific afferent termination zones in the optic tectum of three-eyed tadpoles that were chronically treated with protein kinase inhibitors. The kinase inhibitors sphingosine, H-7, and phorbol ester, which down-regulates protein kinase C with chronic exposure, were applied to the tecta in a slow release plastic, Elvax. In vivo protein phosphorylation assays in drug-treated tadpoles indicated that the treatments decreased 32P incorporation into some protein bands by as much as 60%. Although the drugs did not cause a desegregation of the eye-specific stripes, treated retinal axon arbors covered about half the area covered by untreated arbors or arbors treated with inactive analogs of the drugs. We conclude that eye-specific segregation can be maintained under conditions that markedly alter retinal ganglion cell axon arbor size and that significantly perturb protein phosphorylation. Furthermore, we conclude that the protein kinase(s) that we blocked with these treatments is involved in the growth of axon arbors.
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
Nob mice wave goodbye to eye-specific segregation.
Spontaneous retinal activity is necessary to establish and maintain eye-specific projections to the LGN, but whether the spatial and temporal structure of this activity is important remains unclear. A new study by Demas et al. in the current issue of Neuron shows that when the frequency of spontaneous retinal waves is increased and waves abnormally persist past eye opening, eye-specific projections to the LGN desegregate. These results provide important new insight into the mechanisms that drive eye-specific refinement and stabilization.
Animals↗
Indicators of human health in ecosystems: what do we measure?
Increasingly, scientists are being called upon to assist in the development of indicators for monitoring ecosystem health. For human health indicators, they may draw on environmental exposure, human morbidity/mortality or well-being and sustainability approaches. To improve the rigour of indicators, we propose six scientific criteria for indicator selection: (1) data availability, suitability and representativeness (of populations), (2) indicator validity (face, construct, predictive and convergent) and reliability; (3) indicator responsiveness to change; (4) indicator desegregation capability (across personal and community characteristics); (5) indicator comparability (across populations and jurisdictions); and (6) indicator representativeness (across important dimensions of concern). We comment on our current capacity to adhere to such criteria with examples of measures of environmental exposure, human health and sustainability. We recognize the considerable work still required on documenting environment-human health relationships and on monitoring potential indicators in similar ways over time. Yet we argue that such work is essential in order for science to inform policy decisions which affect the health of ecosystems and human health.
Biomarkers↗
Cytotoxic T lymphocytes versus streptococcal colonization in periapical granulomas.
Seventeen dental periapical lesions were investigated to study bacterial colonization. Periapical lesions, obtained after apicotomy, were also enzymatically desegregated to quantitatively analyze lymphocyte subpopulations by flow cytometry. Fourteen samples yielded a positive bacterial growth when homogenized and cultured. We isolated enough lymphocytes to make flow cytometric analysis from 12 samples. A significant increase in interleukin-2 receptor and ICAM-1 molecule expression on T cells was found, compared with peripheral blood lymphocytes. Furthermore, a decreased expression of interleukin-2 receptors and HLA DR molecules on CD8+ T cells was found in granulomas predominantly colonized by Streptococcus spp., compared with lesions predominantly colonized by strict anaerobes.
Bacteria, Anaerobic↗