Kinetic Monte-Carlo modelling of charge and exciton dynamics in phosphorescent organic light-emitting diodes

Stephen Sanderson studied the operation of phosphorescent organic light-emitting diodes using kinetic Monte-Carlo simulation techniques combined with molecular dynamics modelling for accurate representations of the molecular structure. His research has contributed to an improved understanding of the underlying physical processes in these devices

Militarist, Marxian, and Non-Marxian Materialist Theories of Gender Inequality: A Cross-Cultural Test*

Abstract This study tested three types of theories of gender inequality in preindustrial societies by using half the societies in the Standard Cross-Cultural Sample: militarist, Marxian, and non-Marxian materialist theories. The first phase of the research used simple cross-tabulations with chi-square as a test of significance and gamma as a measure of association. The results from this phase showed no support for militarist theories, some support for Marxian theories, and substantial support for non-Marxian materialist theories. Since the first phase involved no control variables, a second phase was conducted using multivariate analyses. These analyses confirmed that militarist theories must be emphatically rejected, and that both Marxian and non-Marxian materialist variables help determine gender inequality. Non-Marxian materialist variables, however, explain much more of the variance in gender inequality than Marxian variables do. Gender inequality has been a pervasive feature of human social life for millennia. There is widespread, although hardly universal, agreement that all societies have been to some extent male-dominated * An earlier version of this article was presented at the annual meetings of the American Sociological Association, Atlanta, August 2003. Direct correspondence to Stephen Sanderson, Department of Sociology, Indiana University of / Social Forces 83:4, June 2005 explain only the variable aspects. In doing so it tests three competing theories: militarist, Marxian, and non-Marxian materialist theories. Militarist theories The first of several Marxian theories was proposed by Engels ([1884] 1970). Engels argued that in the earliest forms of human society women were equal with men. With the rise of social stratification and the state in social evolution, men gained control over private property and this came to be extended to control over women; as a result, women's status plummeted. Karen According to non-Marxian materialist theories, ecological, technological, and economic factors are the most important determinants of women's status. The greater the extent to which women are involved in economic production, the higher their status tends to be Testing Three Theories of Gender Inequality / 1427 Hypotheses and Methods hy potheses We formulate three hypotheses that correspond to the three theoretical perspectives. Hypothesis 1 is derived from militarist theories: Hypothesis 1: The greater the prevalence of warfare, the lower the status of women. Hypothesis 2 is derived from Marxian theories: Hypothesis 2a: The greater the control women have over the products of their own labor, the higher their status. Hypothesis 2b: The greater the degree of stratification, the lower the status of women. Hypothesis 3 is derived from non-Marxian materialist theories: Hypothesis 3a: The greater the contribution of gathering to the total food supply, the higher the status of women. Hypothesis 3b: The greater the contribution of women to overall subsistence, the higher their status. Hypothesis 3c: In agricultural societies, the greater the contribution of women to agricultural labor, the higher their status. Hypothesis 3d: In agricultural societies, the greater the intensity of cultivation, the lower the status of women. Hypothesis 3e: In patrilineal societies the status of women will be lower than in nonpatrilineal societies. Hypothesis 3f: In patrilocal or virilocal societies the status of women will be lower than in nonpatrilocal or nonvirilocal societies. Data The data set used to test these hypotheses is Murdock and White's (1969) Standard Cross-Cultural Sample, which contains 186 pre-industrial societies. To make the SCCS a representative sample, Murdock and White divided the world into 186 regions and then selected one society from each of the regions. Region selection was intended to solve "Galton's problem" of cultural diffusion. Assuming that diffusion can and will occur when two cultures are in contact with each other, Galton's problem suggests that any sample could be biased by cultural diffusion. Murdock and White solved the problem by selecting regions that were separated by one or more significant geographical boundaries, boundaries that would limit or eliminate contact between neighboring societies. Within each region, the society / Social Forces 83:4, June 2005 that was selected was the best documented society. This means that the SCCS is, strictly speaking, a nonrandom (but nonetheless highly representative) sample. Anthropologists, missionaries, and others have recorded the information about the societies of the SCCS. All ethnographies were gathered prior to 1950 and in most cases before significant impact was made by modern societies. Controversy has surrounded the use of such data sets. Data quality differs from one society to another because of the different kinds of persons -missionaries, travelers, professional ethnographers, etc. --who were collecting the data, their motives for doing so, and their levels of competence. Data sets like the SCCS are still, however, widely used by anthropologists and some sociologists, and such studies have often produced compelling findings. We contend that the various measures used in this study have a high degree of face validity. For example, coding whether societies engaged in warfare, used the plow, or were patrilineal, and the like, are relatively straightforward constructs with meaningful indicators. The more problematic issue, in our view, pertains to the reliability of the measures. Our basic argument, however, is that, since reliability error attenuates correlation coefficients, if statistically and substantively significant findings emerge, then they actually underestimate the strength of the relationships discovered rather than distort the overall pattern of results. Overall, if the data were completely lacking in validity and reliability, then no significant relationships should be found. In 1978, Whyte created gender status variables for the SCCS. In the interest of saving an enormous amount of time and effort, Whyte coded every other society starting with Nama Hottentot and concluding with Tehuelche until he had 93 with which to work (see Whyte 1978 for a list of the 93 societies he coded). Whyte then created a set of 52 dependent variables. For purposes of simplification, he reduced the number of dependent variables by using cluster analysis. This yielded 10 dependent variable scales. These scales are the ones Whyte used in his own research on women's status. dependent variables We used three of Whyte's dependent variable scales as measures of the status of women in preindustrial societies. These scales were chosen over Whyte's seven other scales for two reasons. First, they had the strongest correlations with the independent variables in Whyte's own empirical analyses, which suggest that they are the three best measures of women's status. Second, they most clearly operationalize the concepts in the theoretical categories that we test. We also summed the three measures to create a composite measure of gender inequality. The dependent variable scales are the following: (1) Domestic authority of women, which is a cluster of three dependent variables: final authority over infants, final authority over children, and lack of male dominance over wives. This scale has an average interitem Testing Three Theories of Gender Inequality / 1429 correlation of .375. It is coded low, medium, and high, where the higher the score, the more domestic authority women have. (2) Ritualized female solidarity, which is a cluster of five dependent variables: exclusively male work organizations, exclusively female work organizations, menstrual cycle taboos, female initiation ceremonies, and lack of a belief in female inferiority. This scale has an average interitem correlation of .247. It ranges from low to high, where the higher the score, the greater the ritualized separation between men and women. (3) Control over women's marital and sexual lives (referred to in this article as "male control over female sexuality"), which is a cluster of four dependent variables: lack of a premarital double standard, lack of an extramarital double standard, remarriage ease, and relative age at first marriage. This index of male control over female sexuality has an average interitem correlation of .242 and is dichotomized into stricter and less strict levels of control. (4) Composite gender inequality variable, which is a summed index of the other three independent variables (Cronbach's alpha = .41). We created this variable to strengthen the measurement of gender inequality by creating a more sensitive measure of gender status across societies. The validity of the composite measure is supported by its rather robust correlations with all but two of the Marxian and non-Marxian materialist variables. While the Cronbach's alpha is relatively low, even for a three-item measure, the result will be to underestimate the statistical effects of the independent variables rather than alter the pattern of results. independent variables Three variables from the SCCS data bank were used to measure warfare: Internal warfare: Warfare fought in and around a society's own territories (trichotomized into infrequent, frequent, and continual). External warfare: Warfare fought at considerable distances from a society's own territories (very low, low, moderate, high, very high). Overall warfare: Operationalized as the average of internal and external warfare (very low, low, moderate, high, very high). The Marxian hypothesis was measured by two independent variables: Female economic control of the products of their own labor (absent, present). Class stratification (egalitarian, wealth distinctions only, elite or dual, complex). / Social Forces 83:4, June 2005 The non-Marxian materialist hypothesis and its subtypes were measured by the following independent variables: Percentage of the contribution of gathering to the food supply (none, less than 10%, less than 50% and less than any other, less than 50% but more than any other, more than 50%). Subsistence type (foraging, shifting cultivation with digging sticks, shifting cultivation with metal hoes, intensive agriculture without the plow, intensive agriculture with the plow). Percentage of the contribution of women to overall subsistence (low, moderate, high). Percentage of the female contribution to agriculture (0-10%, 20%-40%, 50%-60%, 70% or more). Intensity of cultivation (no agriculture or casual agriculture, extensive cultivation or horticulture, intensive agriculture with or without irrigation). Use of the plow (absent, present). Patrilineality (yes, no). Patrilocal or virilocal residence (yes, no). data analysis The data analyses were performed in two stages. First, we used ordinary chi-square tests as a test of statistical significance and gamma as a measure of association for bivariate analyses. Thirty-nine bivariate cross-tabulations were conducted to test the hypotheses, one for each combination of an independent and a dependent variable and each hypothesis. To control for potential spuriousness, in the second stage of the analysis we conducted a series of multivariate analyses, one for each of the original dependent variables. For the two dependent variables that were ordinal, domestic authority of women and ritualized female solidarity, we used ordered (proportional odds or cumulative) logistic regression. We also computed unordered multinomial logistic regression equations for comparison. For all models, significance tests suggested that the unordered multinomial logistic regression equations were unnecessary. Therefore, the models were recomputed using ordinary least squares regression and compared to the ordered logistic regressions. Because these models produced identical conclusions, the ordinary least squares regressions are shown for ease of interpretation. For the dichotomous dependent variable, male control over female sexuality, we used binary logistic regression. For the composite gender inequality variable, which ranged in value from 3 to 9, we used ordinary least squares regression. Testing Three Theories of Gender Inequality / 1431 building the models For all four dependent variables, we ran a series of ordered, hierarchical models with the warfare variables entered first into the model, followed by the Marxian variables, and then by the non-Marxian variables. Because of the small sample size, to preserve degrees of freedom and to minimize problems with multicollinearity, we used a stepwise approach by testing the effect of each independent variable in each block one at a time. Because of the small sample size and low power, we retained any independent variable that achieved a one-tailed significance level of p ≤ .10 (see Hosmer and Lemeshow 1989). Variables not achieving a significance level of .10 for entry were not included in the final models. Because the bivariate analyses gave no support for the warfare hypotheses, we entered warfare variables into the models first to give them the greatest opportunity to be included in the final models. We entered the Marxian variables next, because we wanted to give credit for any mutually (with other materialist variables) explained variance to the Marxian variables rather than to the non-Marxian materialist variables. This strategy provided the most conservative test of the non-Marxian materialist theories. We felt our ordered strategy was the most effective way to pit the three theories against one another. In a sense, non-Marxian materialist theories are not contradictory to Marxian explanations; they build upon Marxist explanations. Therefore, if non-Marxian materialist variables were not predictive above and beyond Marxian variables, then this would provide greater support for Marxian models and suggest other materialist variables are not necessary to understand gender inequality. However, if non-Marxian materialist variables were significant determinants of gender inequality after controlling for significant Marxian variables, we could conclude that Marxian theories by themselves are inadequate to explain gender inequality. Results phase 1: bivariate results Militarist Hypothesis / Social Forces 83:4, June 2005 greater the level of warfare, the lower the status of women, has no empirical support. It is true that men dominate the means of warfare, but this does not necessarily prevent women from having a relatively high degree of domestic authority, less strict controls on their sexuality by men, or the ability to form solidarity groups. Divale and Harris's version of the militarist hypothesis focuses on band and tribal societies, whereas Collins is concerned mainly with militarism and warfare in large-scale agrarian societies. Therefore, we computed separate correlations for three different types of societies (results not shown). For hunter-gatherer societies, overall warfare was moderately correlated with female domestic authority (r = -.32), but this was the only correlation that supported the militarist hypothesis. Overall warfare correlated .24 with female solidarity and .25 with male control of female sexuality; and even more striking, external warfare correlated .49 with female solidarity and .52 with male control of female sexuality. These correlations are in the opposite direction from that predicted by the theory. For horticultural societies, female domestic authority and male control of female sexuality were uncorrelated with warfare, but ritualized female solidarity correlated .45 with overall warfare. Finally, for agrarian or intensive agricultural Testing Three Theories of Gender Inequality / 1433 societies, female domestic authority and female solidarity were not correlated with warfare, but male control of female sexuality correlated .38 with overall warfare and .55 with external warfare. Once again, however, all these correlations were in the opposite direction from that predicted by the theory. Thus, there does not appear to be an interaction effect between type of society and warfare, driving yet another nail into the militarist theory's coffin. Marxian Hypothesis Non-Marxian Materialist Hypothesis The 24 tests of the non-Marxian materialist hypothesis are shown in Summary of Bivariate Results In this preliminary segment of the research, there were 39 total tests of three hypotheses (13 independent variables each being associated with 3 dependent variables). The militarist hypothesis received no support at all, failing to achieve statistical significance in any of its statistical tests. The Marxian hypothesis had some support, with three of the six statistical tests being significant and two of the six relationships of at least moderate strength. The non-Marxian materialist hypothesis clearly achieved the best support, with 67% of the 24 statistical tests being significant and 50% of the relationships of moderate to high strength. W

Differential trafficking of AMPA receptors following activation of NMDA receptors and mGluRs

The removal of AMPA receptors from synapses is a major component of long-term depression (LTD). How this occurs, however, is still only partially understood. To investigate the trafficking of AMPA receptors in real-time we previously tagged the GluA2 subunit of AMPA receptors with ecliptic pHluorin and studied the effects of NMDA receptor activation. In the present study we have compared the effect of NMDA receptor and group I mGluR activation, using GluA2 tagged with super ecliptic pHluorin (SEP-GluA2) expressed in cultured hippocampal neurons. Surprisingly, agonists of the two receptors, which are both able to induce chemical forms of LTD, had clearly distinct effects on AMPA receptor trafficking. In agreement with our previous work we found that transient NMDA receptor activation results in an initial decrease in surface GluA2 from extrasynaptic sites followed by a delayed reduction in GluA2 from puncta (putative synapses). In contrast, transient activation of group I mGluRs, using DHPG, led to a pronounced but more delayed decrease in GluA2 from the dendritic shafts. Surprisingly, there was no average change in the fluorescence of the puncta. Examination of fluorescence at individual puncta, however, indicated that alterations did take place, with some puncta showing an increase and others a decrease in fluorescence. The effects of DHPG were, like DHPG-induced LTD, prevented by treatment with a protein tyrosine phosphatase (PTP) inhibitor. The electrophysiological correlate of the effects of DHPG in the SEP-GluA2 infected cultures was a reduction in mEPSC frequency with no change in amplitude. The implications of these findings for the initial mechanisms of expression of both NMDA receptor- and mGluR-induced LTD are discussed