Relative Group Size Research Articles

Ethnic Competition and Specialization

Are ethnic specialization and thus a downward sloping labor demand curve fundamental features of labor market competition between ethnic groups? In a general equilibrium model, this chapter argues that spillover effects in skill acquisition and social distances between ethnic groups engender equilibrium regimes of skill acquisition that differ in their implications for ethnic specialization. Specifically, fundamental relationships through which relative group sizes determine whether ethnic specialization arises and in what degree are established. Thus, this chapter theoretically justifies a downward sloping labor demand curve and explains why some ethnic groups earn more than others, ethnic minorities underperforming or outperforming majorities.

Minority Status Decreases Sense of Control and Increases Interpretive Processing

Relative group size consistently affects social perception. This article proposes that minority members lack subjective control over outcomes, so they engage in interpretative reasoning. In a minimal intergroup procedure, participants believed that they belonged either to a majority or a minority group. They then received information and thought aloud about social targets, with whom they anticipated to interact. As expected, compared to majority members, minority members perceived less control over their outcomes, relied less on factual information, and made more dispositional attributions about social targets. Group size affected processing focus and not processing effort. Sense of control mediated the effect of group size on information processing. These findings illuminate the phenomenology of being a minority.

Social Identity, Political Speech, and Electoral Competition

Much research in political science suggests that social identity can be an important factor in motivating behavior. If voters care about social identity, when will politicians find it in their interests to make group-based appeals? Do social identity concerns affect the policy platforms offered by candidates? In a model of political speech and electoral competition, in which voters care about both social identities and policy, we demonstrate that social identity concerns can lead to platform divergence even when the policy dimension is uncorrelated with identity. For example, policy-motivated politicians can employ identity rhetoric to obtain ‘slack’ in the policy dimension. Further, the need for candidates to resort to group-based appeals depends on such factors as the relative sizes of social groups; the policy preferences of group members; whether candidates care about policy and if so, their preferred policies; and the extent of individual identification with groups. The analysis demonstrates that social identity can have a striking impact on the strategic conduct of campaigns.

The structure, context and functions of group singing in black-breasted wood-quail (Odontophorus leucolaemus)

Black-breasted wood-quail (Odontophorus leucolaemus) are vocal, group living birds (covey size ranges from 2 to 15 individuals) that inhabit the dense understory of highland forest in Costa Rica. Mated pairs produce coordinated duets and groups produce coordinated choruses that are audible to humans from a distance of at least 200 m. Duets and choruses are antiphonal; they consist of two syllables that are comprised of two elements each, which are repeated over and over in an alternating fashion. Neighbouring coveys are most often heard calling back and forth just after dawn and all group members participate in singing and territory defence. During territorial encounters, group singing is often accompanied by displays, chases, and even physical fights between members of opposing coveys. Black-breasted wood-quail produce at least five structurally distinct close-range calls that are associated with within-group communication and territorial encounters. Observations of the context of unprovoked duets and choruses, in addition to responses to simulated territorial intrusion using playback, indicate that these songs play an important role in territory advertisement and defence. Furthermore, black-breasted wood-quail may adjust their response to playback as a function of relative group size, suggesting that choruses could function in relative numerical assessment of group size.

The Effects of Relative Group Size on Occupational Outcomes: Turks and Ex-Yugoslavs in Austria

This paper examines occupational allocation of Turkish and ex-Yugoslav male immigrants in Austria at the end of 1990s. Data from Austrian labour force surveys are utilized to separate the effects of immigrants' individual characteristics from contextual factors related to their spatial location, with particular focus on relative group size. Results largely support the occupational queuing hypothesis, according to which occupational standing of Turks is inversely related to the relative size of the ex-Yugoslav immigrant population, while the occupational fortunes of ex-Yugoslavs are directly proportional to the relative size of the Turkish immigrant population. In addition, it is shown that the occupational standing of Turkish immigrants is positively related to their proportionate size in the labour market, while the opposite is true for ex-Yugoslav immigrants. The native-born Austrian male population seems to have a higher occupational status in areas where the concentration of immigrants is greater.

The organization of the brainstem and spinal cord of the mouse: Relationships between monoaminergic, cholinergic, and spinal projection systems

Information regarding the organization of the CNS in terms of neurotransmitter systems and spinal connections in the mouse is sparse, especially at the level of the brainstem. An overview is presented of monoaminergic and cholinergic systems in the brainstem and spinal cord that were visualized immunohistochemically in inbred C57BL/6 and outbred CD-1 mice. This information is complemented with data on spinal cord-projecting systems that were characterized using retrograde tracing, spinal hemisections, and double labeling techniques. Attention is given to differences in these systems related to spinal levels. The data are discussed with reference to studies in the rat, and to standardized information as provided in the atlas of the mouse brain. Although the overall organization of these systems in the mouse is largely similar to those in the rat, species differences are present in relative location, size and/or connectivity of cell groups. For example, catecholaminergic neurons in the (ventro)lateral pons (A5 and A7 cell groups) in the mouse project to the spinal cord mainly via contralateral, and not ipsilateral, pathways. The data further supplement information as provided in standardized brainstem sections of the C57BL/6 mouse [Paxinos, G., Franklin, K.B.J., 2001. The mouse brain in stereotaxic coordinates. Academic Press, San Diego], especially with respect to the size and/or location of the catecholaminergic retrorubral field (A8 group), A5, A1, and C1 cell groups, and the serotonergic B4 group, reticulotegmental nucleus (B9 group), lateral paragigantocellular nucleus and raphe magnus nucleus (B3 group). Altogether this study provides a comprehensive overview of the spatial relationships of neurochemically and anatomically defined neuronal systems in the mouse brainstem and spinal cord.

An empirical test of Lanchester's square law: mortality during battles of the fire antSolenopsis invicta

Lanchester's models of attrition describe casualty rates during battles between groups as functions of the numbers of individuals and their fighting abilities. Originally developed to describe human warfare, Lanchester's square law has been hypothesized to apply broadly to social animals as well, with important consequences for their aggressive behaviour and social structure. According to the square law, the fighting ability of a group is proportional to the square of the number of individuals, but rises only linearly with fighting ability of individuals within the group. By analyzing mortality rates of fire ants (Solenopsis invicta) fighting in different numerical ratios, we provide the first quantitative test of Lanchester's model for a non-human animal. Casualty rates of fire ants were not consistent with the square law; instead, group fighting ability was an approximately linear function of group size. This implies that the relative numbers of casualties incurred by two fighting groups are not strongly affected by relative group sizes and that battles do not disproportionately favour group size over individual prowess.

Arthropod community structure along a latitudinal gradient: Implications for future impacts of climate change

Abstract The structure of free‐living arthropod communities on the foliage of Acacia falcata was assessed along an extensive latitudinal gradient in eastern Australia. We hypothesized that abundance and biomass of arthropods within feeding groups would increase from temperate latitudes towards the tropics. We also hypothesized that the ratio of carnivores to herbivores would be consistent along the latitudinal gradient. Three sites at each of four latitudes, spanning 9° and 1150 km (Batemans Bay, Sydney, Grafton, Gympie in Australia), were sampled every season for 2 years, using pyrethrum knockdown. Abundance and biomass (based on dry weight) of arthropods within eight feeding groups were measured. The relative size of the feeding groups, and the ratio of carnivores to herbivores were then compared among latitudes and seasons. We found no consistent north to south (tropical to temperate) change in feeding group structure in terms of abundance. A weak latitudinal trend was evident for predator biomass, consisting of a reduction from north to south, but no significant trends in biomass for other feeding groups were found. Relative abundance and relative biomass of both carnivores and herbivores, as well as the ratio of carnivores to herbivores were consistent among latitudes. Finally, we compared a subset of these data to arthropod communities found on congeneric host species at individual sites along the latitudinal gradient. Overall, 68% of comparisons showed no significant differences in abundance or biomass within different feeding groups between host plants and among latitudes. We conclude that arthropod communities show consistencies among latitudes and between congeneric host species, in terms of feeding group and trophic structure. These results have implications for predicting the impacts of future climate change on arthropod communities.

Homogamy among the divorced and the never married on marital history in recent decades: Evidence from vital statistics data

I investigate whether divorced and never married persons tend to marry within their own marital history group. This analysis is a step toward assessing any distinctions that may exist between the never married and the divorced, which informs the distinctions between first marriages and remarriages, across which inequality among coresident children has been observed. Using log-linear models applied to data of marriages formed in a year from the Vital Statistics Marriage Files, I find evidence of a tendency toward marital history homogamy beyond that accounted for by relative group size, education, and age. Specifically, the never married and the divorced are more likely to marry within their marital history group than to intermarry. Results also indicate that, although the tendency toward marital history homogamy unaccounted for by group size, age, and education persisted throughout the period 1970–1988 (i.e., the years for which educational data are available in the Vital Statistics data), it did diminish somewhat.

An approach to studying social disparities in health and health care.

We explored methods and potential applications of a systematic approach to studying and monitoring social disparities in health and health care. Using delayed or no prenatal care as an example indicator, we (1) categorized women into groups with different levels of underlying social advantage; (2) described and graphically displayed rates of the indicator and relative group size for each social group; (3) identified and measured disparities, calculating relative risks and rate differences to compare each group with its a priori most-advantaged counterpart; (4) examined changes in rates and disparities over time; and (5) conducted multivariate analyses for the overall sample and "at-risk" groups to identify particular factors warranting attention. We identified at-risk groups and relevant factors and suggest ways to direct efforts for reducing prenatal care disparities. This systematic approach should be useful for studying and monitoring disparities in other indicators of health and health care.

Attachment of Amine‐ and Maleimide‐Containing Ferrocene Derivatives onto Self‐Assembled Alkanethiol and Alkanedithiol Monolayers: Voltammetric Evaluation of Cross‐Linking Efficiencies and Surface Coverage of Electroactive Groups

AbstractFerrocene derivatives containing primary amines and maleimide groups were attached covalently onto N‐hydrosuccinimidyl (NHS)‐terminated alkanethiol self‐assembled monolayers (SAMs) and SAMs of alkanedithiol. The surface coverage and efficiencies of the two cross‐linking reactions were evaluated with cyclic voltammetry. All the ferrocene derivatives attached onto the alkanethiol or alkanedithiol SAMs exhibit reversible redox waves. The surface coverage of the aminated ferrocene groups was compared to that of N‐hydrosuccinimidyl (NHS)‐terminated alkanethiol SAM. The covalent attachment of β‐ferrocenylethylamine onto a 11,11′‐dithio‐bis(succinimidylundecanoate) SAM yielded an efficiency as high as 63.1%. The cross‐linking efficiency of this reaction was found to increase with the nucleophilicity of the amino groups. SAMs of longer alkyl chains favor the attachment of a greater number of ferrocene derivatives. As for the Michael‐type electrophilic addition between the sulfhydryl groups of the alkanedithiol SAMs and the ferrocenyl maleimide, the cross‐linking efficiencies were found to range from 6.5% to 25.7%, depending on the alkanedithiol chain length. The difference in the efficiencies between the two types of cross‐linking reactions might be partially attributable to the steric hindrance imposed by the SAMs and the relative sizes of the functional groups.

Inter-racial Marriages in South Africa

Using the ten percent sample of the 1996 South African census, we examine the rates of intergroup marriage and marriage between linguistic groups in South Africa. Since whites are a small number in South Africa but historically have held most of the power, the analysis provides an interesting context to test the generalizability of theories about inter-racial marriage. We test exchange theory by examining the effects of education on the patterns of intergroup marriage. We do this while controlling for relative group size. Finally, we examine the socioeconomic status of children of mixed marriages to see possible implications of mixed marriages for future generations. Although education is only weakly related to rates of inter-group marriage, it appears to facilitate outmarriage for low-status groups. More minority females than males marry out of their own group, a pattern of intermarriage quite different from that of the United States. This pattern may reflect local norms, or the different racial composition of the two countries. Children of mixed-white marriages appear to do much better economically than children of mixed-black marriages.

Randomized Clinical Trial of Itopride for the Treatment of Postoperative Ileus after Laparoscopic Cholecystectomy

Background. Postoperative ileus is a distressing and frequent adverse effect after laparoscopic cholecystectomy (LCE). The goal of this prospective study was to evaluate if the new prokinetic drug itopride hydrochloride (Ganaton®, Abbott GmbH Co. KG, Wiesbaden, Germany) may ameliorate the gastric motility in the early post-operative period after LCE. Transcutaneous electrogastrography (EGG), a noninvasive diagnostic method allowing a monitoring of gastric myoelectric activity, was used to evaluate changes of gastric motility. Methods. 50 patients undergoing LCE were observed for 3 days beginning with the day of surgery. The patients were perorally treated with itopride hydrochloride (50 mg per day) or placebo (sacharose) in a randomized double-blind manner. EGG records were done 6, 24, and 48 h after surgery. EGG was performed in a fasting state and after stimulation with a liquid bolus. The EGG data were recorded by a Microdigitrapper device and analyzed using spectral analysis and Fourier transformation. Results. When comparing both groups (itopride and placebo), nausea was found significantly more frequently in the placebo group at the day of surgery as well as on postoperative days 1 and 2. The incidence of vomiting did not differ between both groups. Moreover, there are some differences in the EGG records. On the day of surgery, 40 and 56% of the patients in the placebo and the itopride group showed a physiological EGG curve, respectively. On the 1st postoperative day it was 56 and 68% and on the 2nd postoperative day 80 and 88%. However, these differences failed to reach a significance level of p < 0.05, most likely because of the relative small group sizes. Conclusion. The perioperative use of itopride accelerates the normalization of the EGG curve after LCE. Itopride was well tolerated, and we did not observe serious adverse effects during therapy. Our data suggests that itopride can be a useful accelerator of postoperative ileus restoration after LCE. However, other studies will be necessary to unequivocally prove the beneficial effect of itopride after LCE also in comparison with other commonly used drugs.

Projecting the future of Canada's population: assumptions, implications, and policy

After considering the assumptions for fertility, mortality and international migration, this paper looks at implications of the evolving demographics for population growth, labour force, retirement, and population distribution. With the help of policies favouring gender equity and supporting families of various types, fertility in Canada could avoid the particularly low levels seen in some countries, and remain at levels closer to 1.6 births per woman. The prognosis in terms of both risk factors and treatment suggests further reductions in mortality toward a life expectancy of 85. On immigration, there are political interests for levels as high as 270,000 per year, while levels of 150,000 correspond to the long term post-war average. The future will see slower population growth, and due to migration more than natural increase. International migration of some 225,000 per year can enable Canada to avoid population decline, and sustain the size of the labour force, but all scenarios show much change in the relative size of the retired compared to the labour force population. According to the ratio of persons aged 20-64 to that aged 65 and over, there were seven persons at labour force ages per person at retirement age in 1951, compared to five in 2001 and probably less than 2.5 in 2051. Growth that is due to migration more so than natural increase will accentuate the urbanization trend and the unevenness of the population distribution over space. Past projections have under-projected the mortality improvements and their impact on the relative size of the population at older age groups. Policies regarding fertility, mortality and migration could be aimed at avoiding population decline and reducing the effect of aging, but there is lack of an institutional basis for policy that would seek to endogenize population.

Beyond Black and White: The Present and Future of Multiracial Friendship Segregation

How will racial divisions in student friendship networks change as U.S. schools incorporate a growing Asian and Hispanic population? Drawing on theories of race in assimilation processes and the effects of relative group size on intergroup relations, several hypotheses are developed to address this question. These hypotheses are tested using data on friendships among students in grades 7 to 12 from the National Longitudinal Study of Adolescent Health. Key findings are that (1) cross-race friendships including Asian and Hispanic students are more common than those between white and black students, but race and Hispanic background have significant influences on student friendships that persist over immigrant generations; (2) black or white racial identifications are strongly associated with the friendship choices of Hispanic students; (3) cross-race friendships increase with school racial diversity; and (4) own-group friend selection intensifies for students in small racial minorities in a school. The results support theories of racially segmented patterns of assimilation in primary group relations and suggest that students in small racial minorities seek to maintain a friendship network including several own-race friends. Implications are discussed.

Beyond Black and White: The Present and Future of Multiracial Friendship Segregation

How will racial divisions in student friendship networks change as U.S. schools incorporate a growing Asian and Hispanic population? Drawing on theories of race in assimilation processes and the effects of relative group size on intergroup relations, several hypotheses are developed to address this question. These hypotheses are tested using data on friendships among students in grades 7 to 12 from the National Longitudinal Study of Adolescent Health. Key findings are that (1) cross-race friendships including Asian and Hispanic students are more common than those between white and black students, but race and Hispanic background have significant influences on student friendships that persist over immigrant generations; (2) black or white racial identifications are strongly associated with the friendship choices of Hispanic students; (3) cross-race friendships increase with school racial diversity; and (4) own-group friend selection intensifies for students in small racial minorities in a school. The results support theories of racially segmented patterns of assimilation in primary group relations and suggest that students in small racial minorities seek to maintain a friendship network including several own-race friends. Implications are discussed.

Social structural position and prejudice: an exploration of cross-national differences in regression slopes

Group-threat theorists suggest that increases in the collective threat posed to dominant ethnic and racial groups increase average levels of prejudice and intensify the relationships between individual characteristics and prejudice. However, group-threat theorists focus attention more on differences in the average levels of prejudice across geographic regions and/or time than on differences in the relationships between individual characteristics and prejudice. The purpose of this article is to explore in greater detail possible differences in these relationships—that is, to identify the conditions that intensify or even dampen the relationships between individual characteristics and prejudice. I use relative group size and economic conditions—as suggested by theories of prejudice—to explain variation in the effects of three social structural variables on prejudice (labor market position, education, and income). I use hierarchical linear modeling to analyze multi-level data from 17 East and West European countries. Results indicate that the effects of labor market position, education, and income differ across countries and that the effects are weaker in Eastern Europe compared to Western Europe, largely because of poor economic conditions. There is some support for group-threat theory in that the effect of student status is stronger in countries with larger immigrant populations. However, in opposition to group-threat theory, countries with poor economic conditions have weaker relationships between the social structural variables and prejudice. Thus, results suggest a revision of group-threat theory—indicators of group-threat have different effects on the relationships between individual characteristics and prejudice.

Regulation of neuronal survival and death by extracellular signals during development.

Cell death is a prominent feature of the developing vertebrate nervous system, affecting neurons, glial cells and their progenitors. The most extensively studied and best understood phase of cell death occurs in populations of neurons shortly after they begin establishing connections with other neurons and/or non-neural tissues. This phase of cell death makes appropriate adjustments to the relative sizes of interconnected groups of neurons and matches the size of neuronal populations that innervate non-neural tissues to the optimal requirements of these tissues. The fate of neurons during this period of development is regulated by a variety of secreted proteins that either promote survival or bring about cell death after binding to receptors expressed on the neurons. These proteins may be derived from the targets the neurons innervate, the afferents they receive or from associated glial cells, or they may be secreted by the neurons themselves. In this review, I will outline the established and emerging principles that modulate neuronal number in the developing nervous system.

Fitness consequences of sociality in prairie voles, Microtus ochrogaster: influence of group size and composition

We used 7 years of live-trapping data from an Illinois population of prairie voles to examine how survival and reproductive success varied with size and composition of social groups. Specifically, we examined measures of fitness for residents of single female units, male–female pairs and communal groups. Reproductive success, measured as either the number of young that survived to 12 or 30 days of age per adult female in a group, was higher for groups of three adults than for smaller or larger groups. The ideal group composition with respect to reproductive success appeared to be one adult female and two adult males. Individuals born into groups with three adults survived longer than did those born into smaller or larger groups. There was no clear relationship, however, between group size and survival of adult members of groups. Sudden disappearance of a group, presumably to predation by weasels, was associated with relative group size such that the largest groups were more likely to disappear. Overall, our data indicate that prairie voles living in communal groups with three adult members have higher fitness than those living in smaller groups or in larger communal groups. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

Effects of minority status in the classroom on children’s intergroup attitudes

Three studies examined the effects of relative group size on the development of children’s intergroup attitudes. The studies employed a novel group paradigm in which elementary school children attending a summer school program were assigned to larger (i.e., majority) or smaller (i.e., minority) novel groups in their classroom (denoted by colored tee-shirts). In each study, relative group size was situated within a different classroom context. Study 1 examined the effects of relative group size when teachers made functional use of the novel groups and were themselves members of the novel groups. Study 2 examined the effects of relative group size in the absence of functional use. Study 3 examined the effects of relative group size when the classroom environment contained implicit messages about group status. In each study, children’s intergroup attitudes (e.g., trait ratings, group evaluations) were assessed following several weeks in the classroom. The effect of relative group size on in-group bias was complex, varying as a function of (a) the relative size and salience of groups, (b) the measure used to assess intergroup attitudes, (c) group status (higher or lower), and (d) children’s age.