Experimental investigation of 3-D MHD flows at high Hartmann number and interaction parameters

Experimental investigations of 3-D MHD flows in uniform thin conducting wall ducts of circular and square cross section, conducted at Argonne National Laboratory's ALEX facility, are reported. The three-dimensional nature of the flow arises from the spacial variation of the applied transverse magnetic field. Measurements were performed at several Hartmann numbers, M, and interaction parameters, N, with the peak value for M exceeding 6 /times/ 10/sup 3/ and the peak value for N exceeding 10/sup 5/. Typical results and their comparison to numerical analysis reported in a companion paper are given, as is a brief description of the ALEX facility and the experimental methods employed. Ongoing activities and plans for future experiments are also discussed. 6 refs., 3 figs

MHD considerations for a self-cooled liquid lithium blanket

The magnetohydrodynamic (MHD) effects can present a feasibility issue for a self-cooled liquid metal blanket of magnetically confined fusion reactors, especially inboard regime of a tokamak. This pressure drop can be significantly reduced by using insulated wall structure. A self-healing insulating coating has been identified, which will reduce the pressure drop by more than a factor of 10. The future research direction to further quantify the performance of this coating is also outlined

MHD considerations for a self-cooled liquid lithium blanket

The magnetohydrodynamic (MHD) effects can present a feasibility issue for a self-cooled liquid metal blanket of magnetically confined fusion reactors, especially inboard regime of a tokamak. This pressure drop can be significantly reduced by using insulated wall structure. A self-healing insulating coating has been identified, which will reduce the pressure drop by more than a factor of 10. The future research direction to further quantify the performance of this coating is also outlined

INTOR first wall/blanket/shield activity

The main emphasis of the INTOR first wall/blanket/shield (FWBS) during this period has been upon the tritium breeding issues. The objective is to develop a FWBS concept which produces the tritium requirement for INTOR operation and uses a small fraction of the first wall surface area. The FWBS is constrained by the dimensions of the reference design and the protection criteria required for different reactor components. The blanket extrapolation to commercial power reactor conditions and the proper temperature for power extraction have been sacrificed to achieve the highest possible local tritium breeding ratio (TBR). In addition, several other factors that have been considered in the blanket survey study include safety, reliability, lifetime fluence, number of burn cycles, simplicity, cost, and development issues. The implications of different tritium supply scenarios were discussed from the cost and availability for INTOR conditions. A wide variety of blanket options was explored in a preliminary way to determine feasibility and to see if they can satisfy the INTOR conditions. This survey and related issues are summarized in this report. Also discussed are material design requirements, thermal hydraulic considerations, structure analyses, tritium permeation through the first wall into the coolant, and tritium inventory

The population biology and evolutionary significance of Ty elements in Saccharomyces cerevisiae

The basic structure and properties of Ty elements are considered with special reference to their role as agents of evolutionary change. Ty elements may generate genetic variation for fitness by their action as mutagens, as well as by providing regions of portable homology for recombination. The mutational spectra generated by Ty 1 transposition events may, due to their target specificity and gene regulatory capabilities, possess a higher frequency of adaptively favorable mutations than spectra resulting from other types of mutational processes. Laboratory strains contain between 25–35 elements, and in both these and industrial strains the insertions appear quite stable. In contrast, a wide variation in Ty number is seen in wild isolates, with a lower average number/genome. Factors which may determine Ty copy number in populations include transposition rates (dependent on Ty copy number and mating type), and stabilization of Ty elements in the genome as well as selection for and against Ty insertions in the genome. Although the average effect of Ty transpositions are deleterious, populations initiated with a single clone containing a single Ty element steadily accumulated Ty elements over 1,000 generations. Direct evidence that Ty transposition events can be selectively favored is provided by experiments in which populations containing large amounts of variability for Ty1 copy number were maintained for ∼100 generations in a homogeneous environment. At their termination, the frequency of clones containing 0 Ty elements had decreased to ∼0.0, and the populations had became dominated by a small number of clones containing >0 Ty elements. No such reduction in variability was observed in populations maintained in a structured environment, though changes in Ty number were observed. The implications of genetic (mating type and ploidy) changes and environmental fluctuations for the long-term persistence of Ty elements within the S. cerevisiae species group are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42799/1/10709_2004_Article_BF00133718.pd

Magnetohydrodynamic considerations for the design of self-cooled liquid-metal fusion reactor blankets

During the course of the Blanket Comparison and Selection Study, magnetohydrodynamic effects were shown to prevent not only an efficiency but also a feasibility issue for self-cooled liquid-metal blankets, especially for tokamak machines. Based on state-of-the art MHD analyses and understanding of related phenomena, designs for both mirror and tokamak machines were developed. Although details of the designs depend on specific reactor parameters, MHD related considerations were the main driver in the development of the designs. This paper presents, in a unified way, these considerations, as well as effective strategies to minimize adverse MHD effects so that they can be used as guidelines by others in future design efforts

TWO PROBLEMS OF FLUID-MECHANICS OF PHYSIOLOGICAL SYSTEMS: I. BIORHEOLOGICAL ASPECTS OF INTESTINAL MOTILITY. II. RADIALMIGRATION OF DILUTE SUSPENSIONS IN POISEUILLE FLOW.

Abstract not availabl

SONLESS AND DAUGHTERLESS, TWO SEX SELECTIVE EMBRYONIC LETHAL GENES OF DROSOPHILA MELANOGASTER.

Abstract not availabl

Sidewall flow instabilities in liquid metal MHD flow under blanket relevant conditions

A flow instability has been observed in a rectangular thin conducting wall duct in MHD experiments at ANL's ALEX facility. It developed in a side layer jet attached to a side wall parallel to the applied B-field. The nature of the instability resembles very strongly that of a classic laminar instability in ordinary fluid mechanics. The phenomenon is distinguished from ordinary turbulence by its strong periodicity and its lack of small scale structure. A preliminary identification of the factors which may influence the instability has been made. For the conditions and test section geometry reported here, the instability appears at an approximately constant critical Reynolds number 2650 < Re/sub cr/ < 5100, independent of Hartmann number in the range 2700 < M < 5400. 6 refs., 18 figs

Technical editing and the effective communication of scientific results

Communication of scientific results--whether for professional journals, poster sessions, oral presentations, or the popular press--is an essential part of any scientific investigation. The technical editor plays an important rolein ensuring that scientists express their results correctly and effectively. Technical editing comprises far more than simple proofreading. The editor`s tasks may range from restructuring whole parpagrphs and suggesting improved graphical aids to writing abstracts and preparing first drafts of proposals. The technical editor works closely with scientists to present complex ideas to differentaudiences, including fellow scentists, funding agencies, and the general public. New computer technologyhas also involved the technical editor not only with on-line editing but also with preparing CD ROMs and World Wide Web pages