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X-ray investigations of Pr2CuO4 and La2CuO4 under pressure have been carried out at 300 K and 30 K. The lattice parameters decrease monotonically for both structures, thus preserving the structure of the materials. For La2CuO4 the lattice parameter reduction is isotropic with increasing pressure, but the lattice parameters of Pr2CuO4 are found to behave anisotropic, as the c-axis decreases faster than the a-axis. La2CuO4 has a bulk modulus of 1850 kbar at 300 K, whereas Pr2CuO4 has a bulk modulus of 1600 kbar at 300 K and 1650 kbar at 30 K, due to the faster decreasing c-axis lattice parameter. In the a and b direction both materials have a similar compressibility. Assigning this behaviour to the common copper-oxide layers of both structures gives the possibility to generalize these results. For several high temperature superconductors we estimated the linear compressibilities in the a, b direction being in the range of 1.5 to 2.0×10-4 kbar-1. In the c-direction the compressibility apparently depends on the degeneracy of the oxygen octahedra and the number of intercalated layers orstructural elements. © 1989.

We demonstrate laser frequency stabilization with at least 6 GHz of offset tunability using an in-phase/quadrature (IQ) modulator to generate electronic sidebands (ESB) on a titanium sapphire laser at 714 nm and we apply this technique to perform isotope shift spectroscopy of 226 Ra and 225 Ra. By locking the laser to a single resonance of a high finesse optical cavity and adjusting the lock offset, we determine the frequency difference between the magneto-optical trap (MOT) transitions in the two isotopes to be 2630.0 ± 0.3 MHz, a factor of 29 more precise than the previously available data. Using the known value of the hyperfine splitting of the 3 P 1 level, we calculate the isotope shift for the 1 S 0 to 3 P 1 transition to be 2267.0 ± 2.2 MHz, a factor of 8 more precise than the best available value. Our technique could be applied to countless other atomic systems to provide unprecedented precision in isotope shift spectroscopy and other relative frequency comparisons.

Explanations for protoplasmic streaming began with appeals to contraction in the eighteenth century and ended with appeals to contraction in the twentieth. During the intervening years, biologists proposed a diverse array of mechanisms for streaming motions. This paper focuses on the re-emergence of contraction among the molecular mechanisms proposed for protoplasmic streaming during the twentieth century. The revival of contraction is a result of a broader transition from colloidal chemistry to a macromolecular approach to the chemistry of proteins, the recognition of the phenomena of shuttle streaming and the pulse of protoplasm, and the influential analogy between protoplasmic streaming and muscle contraction., (© 2014 Institute of Botany, Chinese Academy of Sciences.)

In 1990, the National Institutes of Health (NIH) gave some organisms special status as designated model organisms. This article documents publication trends for these NIH-designated model organisms over the past 40 years. We find that being designated a model organism by the NIH does not guarantee an increasing publication trend. An analysis of model and nonmodel organisms included in GENETICS since 1960 does reveal a sharp decline in the number of publications using nonmodel organisms yet no decline in the overall species diversity. We suggest that organisms with successful publication records tend to share critical characteristics, such as being well developed as standardized, experimental systems and being used by well-organized communities with good networks of exchange and methods of communication., (Copyright © 2014 by the Genetics Society of America.)

Richard Goldschmidt was one of the most controversial biologists of the mid-twentieth century. Rather than fade from view, Goldschmidt's work and reputation has persisted in the biological community long after he has. Goldschmidt's longevity is due in large part to how he was represented by Stephen J. Gould. When viewed from the perspective of the biographer, Gould's revival of Goldschmidt as an evolutionary heretic in the 1970s and 1980s represents a selective reinvention of Goldschmidt that provides a contrast to other kinds of biographical commemorations by scientists.

The vast network of Drosphila geneticists spawned by Thomas Hunt Morgan's fly room in the early 20th century has justifiably received a significant amount of scholarly attention. However, most accounts of the history of Drosophila genetics focus heavily on the "boss and the boys," rather than the many other laboratory groups which also included large numbers of women. Using demographic information extracted from the Drosophila Information Service directories from 1934 to 1970, we offer a profile of the gendered division of labor within Drosophila genetics in the United States during the middle decades of the 20th century. Our analysis of the gendered division of labor supports a reconsideration of laboratory practices as different forms of work.

Through a case study of the controversies surrounding the molecular clock, this paper examines the role of visual representation in the dynamics of scientific controversies. Representations of the molecular clock themselves became objects of controversy and so were not a means for closure. Instead visual representations of the molecular clock became tools for the further articulation of an ongoing controversy.

In this article, we consider the tension between unification and pluralism in biological theory. We begin with a consideration of historical efforts to establish a unified understanding of evolution in the neo-Darwinian synthesis. The fragmentation of the evolutionary synthesis by molecular evolution suggests the limitations of the general unificationist ideal for biology but not necessarily for integrating explanations. In the second half of this article, we defend a specific variety of pluralism that allows for the integration required for explanations of complex phenomena without unification on a large scale.

Using an analogy between moths and men, in 1916, Richard Goldschmidt proposed that homosexuality was a case of genetic intersexuality. As he strove to create a unified theory of sex determination that would encompass animals ranging from moths to men, Goldschmidt's doubts grew concerning the association of homosexuality with intersexuality until, in 1931, he dropped homosexuality from his theory of intersexuality. Despite Goldschmidt's explicit rejection of his theory of homosexuality, Theo Lang, a researcher in the Genealogical-Demographic Department of the Institute for Psychiatric Research in Munich, revived it, maintained Goldschmidt's association with it, and argued on its behalf in publications from 1936 to 1960. Lang's appropriation of Goldschmidt's theory did not depend on his resolution of the difficulties Goldschmidt had found with his own theory. Lang and Goldschmidt, I argue, had fundamentally different scientific and social commitments that allowed one to reject this theory of homosexuality and the other to accept it.