Dusty Plasma Correlation Function Experiment

Dust particles immersed within a plasma environment, such as those in protostellar clouds, planetary rings or cometary environments, will acquire an electric charge. If the ratio of the inter-particle potential energy to the average kinetic energy is high enough the particles will form either a "liquid" structure with short-range ordering or a crystalline structure with long range ordering. Many experiments have been conducted over the past several years on such colloidal plasmas to discover the nature of the crystals formed, but more work is needed to fully understand these complex colloidal systems. Most previous experiments have employed monodisperse spheres to form Coulomb crystals. However, in nature (as well as in most plasma processing environments) the distribution of particle sizes is more randomized and disperse. This paper reports experiments which were carried out in a GEC rf reference cell modified for use as a dusty plasma system, using varying sizes of particles to determine the manner in which the correlation function depends upon the overall dust grain size distribution. (The correlation function determines the overall crystalline structure of the lattice.) Two dimensional plasma crystals were formed of assorted glass spheres with specific size distributions in an argon plasma. Using various optical techniques, the pair correlation function was determined and compared to those calculated numerically.Comment: 6 pages, Presented at COSPAR '0

Finite Coulomb Crystal Formation

Dust particles immersed within a plasma environment, such as those found in planetary rings or comets, will acquire an electric charge. If the ratio of the inter-particle potential energy to average kinetic energy is large enough the particles will form either a "liquid" structure with short-range ordering or a crystalline structure with long-range ordering. Since their discovery in laboratory environments in 1994, such crystals have been the subject of a variety of experimental, theoretical and numerical investigations. Most numerical and theoretical investigations have examined infinite systems assuming periodic boundary conditions. Since experimentally observed crystals can be comprised of a few hundred particles, this often leads to discrepancies between predicted theoretical results and experimental data. In addition, recent studies have concentrated on the importance of random charge variations between individual dust particles, but very little on the importance of size variations between the grains. Such size variations naturally lead to inter-grain charge variations which can easily become more important than those due to random charge fluctuations (which are typically less than one percent). Although such size variations can be largely eliminated experimentally by introducing mono-dispersive particles, many laboratory systems and all astrophysical environments contain significant size distributions. This study utilizes a program to find the equilibrium positions of a dusty plasma system as well as a modified Barnes-Hut code to model the dynamic behavior of such systems. It is shown that in terms of inter-particle spacing and ordering, finite systems are significantly different than infinite ones, particularly for the most-highly ordered states.Comment: 6 pages, Presented at COSPAR '0

Numerical Simulations and Analysis of Thermally Excited Waves in Plasma Crystals

A numerical model for a 2D-monolayer plasma crystal was established using the Box_tree code. Box_tree is a Barnes_Hut tree code which has proven effective in modeling systems composed of large numbers of particles. Thermally excited waves in this plasma crystal were numerically simulated and dispersion relations for both the longitudinal and transverse wave modes were found. These were compared with the dispersion relations extrapolated from experiment as well as a theory based on harmonic approximation. The results were found to agree with theoretical dispersion relations under different wave propagation directions with different particle charges and over a range of 0.9<k<5.Comment: 7 pages, Presented at COSPAR '0

Decomposing culture: An analysis of gender, language, and labor supply in the household

Despite broad progress in closing many dimensions of the gender gap around the globe, recent research has shown that traditional gender roles can still exert a large influence on female labor force participation, even in developed economies. This paper empirically analyzes the role of culture in determining the labor market engagement of women within the context of collective models of household decision making. In particular, we use the epidemiological approach to study the relationship between gender in language and labor market participation among married female immigrants to the U.S. We show that the presence of gender in language can act as a marker for culturally acquired gender roles and that these roles are important determinants of household labor allocations. Female immigrants who speak a language with sex-based grammatical rules exhibit lower labor force participation, hours worked, and weeks worked. Our strategy of isolating one component of culture reveals that roughly two thirds of this relationship can be explained by correlated cultural factors, including the role of bargaining power in the household and the impact of ethnic enclaves, and that at most one third is potentially explained by language having a causal impact

Language and Gender Roles among Immigrants to the US: A Historical Perspective

Our paper investigates whether historical trends in the labor market participation of immigrant women in the U.S. can be explained in part by variation in the grammatical structure of their language spoken. Using individual-level census data on the labor market behavior of first generation immigrants to the U.S. from 1910 to the present, we show that the presence or absence of grammatical gender in the linguistic structure of a language spoken by an immigrant influences sex-specific behaviors. The originality of our approach is to consider language as a repository for accumulated ancestral culture in an epidemiological framework. Because female labor force participation has greatly increased, institutions have transformed, and motivations and compositions of immigrant flows have changed, studying a long time horizon allows us to more clearly isolate the role of linguistic structure as a cultural institution

Migration as a Window into the Coevolution between Language and Behavior

Understanding the causes and consequences of language evolution in relation to social factors is challenging as we generally lack a clear picture of how languages coevolve with historical social processes. Research analyzing the relation between language and socio-economic factors relies on contemporaneous data. Because of this, such analysis may be plagued by spurious correlation concerns coming from the historical co-evolution and dependency of the relationship between language and behavior to the institutional environment. To solve this problem, we propose migrations to the same country as a microevolutionary step that may uncover constraints on behavior. We detail strategies available to other researchers by applying the epidemiological approach to study the correlation between sex-based gender distinctions and female labor force participation. Our main finding is that language must have evolved partly as a result of cultural change, but also that it may have directly constrained the evolution of norms. We conclude by discussing implications for the coevolution of language and behavior, and by comparing different methodological approaches

Numerical Study of Structural Phase Transitions in a Vertically Confined Plasma Crystal

Dusty plasmas consists of an ionized gas containing small (usually negatively charged) particles. Dusty plasmas are of interest in both astrophysics and space physics as well as in research in plasma processing and nanofabrication. In this work, the formation of plasma crystals confined in an external one-dimensional parabolic potential well is simulated for a normal experimental environment employing a computer code called BOX_TREE. Such crystals are layered systems, with each layer a two dimensional lattice composed of grain particles. The number of layers is dependent upon the external potential parameter. For constant layer number, the intralayer structure transits from a square lattice to a hexagonal (triangular) lattice as the confining potential decreases. For hexagonal lattices, both hcp and fcc characteristics were found but hcp structures dominate. The relative thickness of the system was also examined. The results were compared with previous experimental and theoretical results and found to agree

Linguistic Structures and Economic Outcomes

Linguistic structures have recently started to attract attention from economists as determinants of economic phenomena. This paper provides the first comprehensive review of this nascent literature and its achievements so far. First, we explore the complex connections between language, culture, thought and behaviour. Then, we summarize the empirical evidence on the relationship between linguistic structures and economic and social outcomes. We follow up with a discussion of data, empirical design and identification. The paper concludes by discussing implications for future research and policy

Decomposing culture: An analysis of gender, language, and labor supply in the household

Despite broad progress in closing many dimensions of the gender gap around the globe, recent research has shown that traditional gender roles can still exert a large influence on female labor force participation, even in developed economies. This paper empirically analyzes the role of culture in determining the labor market engagement of women within the context of collective models of household decision making. In particular, we use the epidemiological approach to study the relationship between gender in language and labor market participation among married female immigrants to the U.S. We show that the presence of gender in language can act as a marker for culturally acquired gender roles and that these roles are important determinants of household labor allocations. Female immigrants who speak a language with sex-based grammatical rules exhibit lower labor force participation, hours worked, and weeks worked. Our strategy of isolating one component of culture reveals that roughly two thirds of this relationship can be explained by correlated cultural factors, including the role of bargaining power in the household and the impact of ethnic enclaves, and that at most one third is potentially explained by language having a causal impact