Book Review: Abortion and Infanticide. by Michael Tooley; Abortion and the Politics of Motherhood. by Kristin Luker; the Law Giveth: Legal Aspects of the Abortion Controversy. by Barbara Milbauef.

Book review: Abortion and Infanticide. By Michael Tooley.Oxford: Clarendon Press. 1983. Pp. 441 ; Abortion and the Politics of Motherhood. By Kristin Luker. Berkeley: University of California Press. 1984. Pp. xvi, 324 ; The Law Giveth: Legal Aspects of the Abortion Controversy. By Barbara Milbauef. New York: Atheneum. 1983. Pp. xiii, 363. All reviewed by Robert H King

Four Lessons From Wal-Mart v. Dukes and Their Application to Montana Class Action Law

Four Lessons From Wal-Mart v. Dukes and Their Application to Montana Class Action La

Parasexual genetics of Dictyostelium gene disruptions: identification of a ras pathway using diploids

BACKGROUND: The relative ease of targeted gene disruption in the social amoeba Dictyostelium has stimulated its widespread use as an experimental organism for cell and developmental biology. However, the field has been hamstrung by the lack of techniques to recombine disrupted genes. RESULTS: We describe new techniques for parasexual fusion of strains in liquid medium, selection and maintenance of the resulting stable diploid strains, and segregation to make recombined haploids. We have used these techniques to isolate rasS/gefB double nulls. The phenotypes of these mutants are no more severe than either parent, with movement, phagocytosis and fluid-phase endocytosis affected to the same degree as in rasS or gefB single nulls. In addition, we have produced diploids from one AX2- and one AX3-derived parent, providing an axenic strain with fewer secondary phenotypes than has been previously available. CONCLUSIONS: The phenotype of the rasS/gefB double mutant suggests that the RasS and GefB proteins lie on the same linear pathway. In addition, axenic diploids and the techniques to generate, maintain and segregate them will be productive tools for future work on Dictyostelium. They will particularly facilitate generation of multiple mutants and manuipulation of essential genes

Differentiation of Schistosoma haematobium from related schistosomes by PCR amplifying an inter-repeat sequence.

Schistosoma haematobium infects nearly 150 million people, primarily in Africa, and is transmitted by select species of local bulinid snails. These snails can host other related trematode species as well, so that effective detection and monitoring of snails infected with S. haematobium requires a successful differentiation between S. haematobium and any closely related schistosome species. To enable differential detection of S. haematobium DNA by simple polymerase chain reaction (PCR), we designed and tested primer pairs from numerous newly identified Schistosoma DNA repeat sequences. However, all pairs tested were found unsuitable for this purpose. Differentiation of S. haematobium from S. bovis, S. mattheei, S. curassoni, and S. intercalatum (but not from S. margrebowiei) was ultimately accomplished by PCR using one primer from a newly identified repeat, Sh110, and a second primer from a known schistosomal splice-leader sequence. For evaluation of residual S. haematobium transmission after control interventions, this differentiation tool will enable accurate monitoring of infected snails in areas where S. haematobium is sympatric with the most prevalent other schistosome species

Stochastic Trends and Economic Fluctuations

Recent developments in macroeconomic theory emphasize that transient economic fluctuations can arise as responses to changes in long run factors -- in particular, technological improvements -- rather than short run factors. This contrasts with the view that short run fluctuations and shifts in long run trends are largely unrelated. We examine empirically the effect of shifts in stochastic trends that are common to several macroeconomic series. Using a linear time series model related to a VAR, we consider first a system with GNP, consumption and investment with a single common stochastic trend; we then examine this system augmented by money and prices and an additional stochastic trend. Our results suggest that movements in the "real" stochastic trend account for one-half to two-thirds of the variation in postwar U.S. GNP.

Replacement of the essential Dictyostelium Arp2 gene by its Entamoeba homologue using parasexual genetics

<p>Abstract</p> <p>Background</p> <p>Cell motility is an essential feature of the pathogenesis and morbidity of amoebiasis caused by <it>Entamoeba histolytica</it>. As motility depends on cytoskeletal organisation and regulation, a study of the molecular components involved is key to a better understanding of amoebic pathogenesis. However, little is known about the physiological roles, interactions and regulation of the proteins of the <it>Entamoeba </it>cytoskeleton.</p> <p>Results</p> <p>We have established a genetic strategy that uses parasexual genetics to allow essential <it>Dictyostelium discoideum </it>genes to be manipulated and replaced with modified or tagged homologues. Our results show that actin related protein 2 (Arp2) is essential for survival, but that the <it>Dictyostelium </it>protein can be complemented by <it>E. histolytica </it>Arp2, despite the presence of an insertion of 16 amino acids in an otherwise highly conserved protein. Replacement of endogenous Arp2 with <it>myc</it>-tagged <it>Entamoeba </it>or <it>Dictyostelium </it>Arp2 has no obvious effects on growth and the protein incorporates effectively into the Arp2/3 complex.</p> <p>Conclusion</p> <p>We have established an effective two-step method for replacing genes that are required for survival. Our protocol will allow such genes to be studied far more easily, and also allows an unambiguous demonstration that particular genes are truly essential. In addition, cells in which the <it>Dictyostelium </it>Arp2 has been replaced by the <it>Entamoeba </it>protein are potential targets for drug screens.</p

Cooling of cryogenic electron bilayers via the Coulomb interaction

Heat dissipation in current-carrying cryogenic nanostructures is problematic because the phonon density of states decreases strongly as energy decreases. We show that the Coulomb interaction can prove a valuable resource for carrier cooling via coupling to a nearby, cold electron reservoir. Specifically, we consider the geometry of an electron bilayer in a silicon-based heterostructure, and analyze the power transfer. We show that across a range of temperatures, separations, and sheet densities, the electron-electron interaction dominates the phonon heat-dissipation modes as the main cooling mechanism. Coulomb cooling is most effective at low densities, when phonon cooling is least effective in silicon, making it especially relevant for experiments attempting to perform coherent manipulations of single spins.Comment: 9 pages, 5 figure