Painting of human chromosomes with probes generated from hybrid cell lines by PCR with Alu and L1 primers

Specific amplification of human sequences of up to several kb length has recently been accomplished in man-hamster and man-mouse somatic hybrid cell DNA by IRS-PCR (interspersed repetitive sequence — polymerase chain reaction). This approach is based on oligonucleotide primers that anneal specifically to human Alu- or L1-sequences and allows the amplification of any human sequences located between adequately spaced, inverted Alu- or L1-blocks. Here, we demonstrate that probe pools generated from two somatic hybrid cell lines by Alu- and L1-PCR can be used for chromosome painting in normal human lymphocyte metaphase spreads by chromosomal in situ suppression (CISS-) hybridization. The painted chromosomes and chromosome subregions directly represent the content of normal and deleted human chromosomes in the two somatic hybrid cell lines. The combination of IRS-PCR and CISS-hybridization will facilitate and improve the cytogenetic analysis of somatic hybrid cell panels, in particular, in cases where structurally aberrant human chromosomes or human chromosome segments involved in interspecies translocations cannot be unequivocally identified by classical banding techniques. Moreover, this new approach will help to generate probe pools for the specific delineation of human chromosome subregions for use in cytogenetic diagnostics and research without the necessity of cloning

Swiss Exchange Rate Policy in the 1930s. Was the Delay in Devaluation Too High a Price to Pay for Conservatism?

In this paper we examine the experience of Switzerland’s devaluation in 1936. The Swiss case is of interest because Switzerland was a key member of the gold bloc, and much of the modern academic literature on the Great Depression tries to explain why Switzerland and the other gold bloc countries, France, and the Netherlands, remained on the gold standard until the bitter end. We ask the following questions: what were the issues at stake in the political debate? What was the cost to Switzerland of the delay in the franc devaluation? What would have been the costs and benefits of an earlier exchange rate policy? More specifically, what would have happened if Switzerland had either joined the British and devalued in September 1931, or followed the United States in April 1933? To answer these questions we construct a simple open economy macro model of the interwar Swiss economy. On the basis of this model we then posit counterfactual scenarios of alternative exchange rate pegs in 1931 and 1933. Our simulations clearly show a significant and large increase in real economic activity. If Switzerland had devalued with Britain in 1931, the output level in 1935 would have been some 18 per cent higher than it actually was in that year. If Switzerland had waited until 1933 to devalue, the improvement would have been about 15 per cent higher. The reasons Switzerland did not devalue earlier reflected in part a conservatism in policy making as a result of the difficulty of making exchange rate policy in a democratic setting and in part the consequence of a political economy which favored the fractionalization of different interest groups.

A comparison of two trusses for the space station structure

The structural performance of two truss configurations, the orthogonal tetrahedral and a Warren-type, are compared using finite element models representing the November Reference Phase 1 Space Station. The truss torsional stiffness properties and fundamental torsion frequency are determined using cantilever truss-beam models. Frequencies, mode shapes, transient response, and truss strut compressive loads are compared for the two space station models. The performance benefit resulting from using a high modulus truss strut is also presented. Finally, assembly and logistics characteristics of the two truss configurations are evaluated

Interactions between structure and stochasticity in demogaphic models

Demography is the study of population dynamics. Populations can be considered as groups of individuals living within a given region. These simple statements encompass highly disparate systems, which respond to demographic and environmental stochasticity in predictable and unpredictable ways. The responses depend on the structure of the population, since individuals can have vastly different survival and recruitment, which, with dispersal, determine population abundance. Whilst some variation is inter-st(age) – increases in reproductive performance with age, for example – substantial intra-st(age) variation is not uncommon. Using longterm individual-based data on two disparate vertebrate populations, the focus of this thesis is the interaction between structure and stochasticity in demographic models, and consequences on resultant aspects of population growth. Structured models that incorporated variation in demographic rates detected marked differences within, between and across diverse habitats for different age-classes in both populations. These results were consistent for a wide range of scaling and definition to account for mathematical dependence. Spatial structure was more influential than age-structure in responses to stochastic predation. Despite significant changes in performance and phenotype with age, individual heterogeneity within ageclasses was vast. These results are of importance for conservation and management action, as well as predictors of evolutionary change. The population is a fundamental force in ecology and evolution. This work adds weight to the argument that characteristics of individual performance in response to variability in their environments are pivotal to increased understanding of changes in population abundance. These individual responses are dependent upon the opportunity generated by population structure. A failure to incorporate either structure or stochasticity neglects crucial aspects in population regulation, and therefore ecological and evolutionary change

Modeling and optimization of a regenerative fuel cell system using the ASPEN process simulator

The Hydrogen-Oxygen Regenerative Fuel Cell System was identified as a key component for energy storage in support of future lunar missions. Since the H2-O2 regenerative electrochemical conversion technology has not yet been tested in space applications, it is necessary to implement predictive techniques to develop initial feasible system designs. The ASPEN simulation software furnishes a constructive medium for analyzing and for optimizing such systems. A rudimentary regenerative fuel cell system design was examined using the ASPEN simulator and this modular approach allows for easy addition of supplementary ancillary components and easy integration with life support systems. The modules included in the preliminary analyses may serve as the fundamental structure for more complicated energy storage systems