16,529 research outputs found

    Gypsy moths and American dog ticks: Space partners

    Get PDF
    An experiment intended for the space shuttle and designed to investigate the effects of weightlessness and total darkness on gypsy moth eggs and engorged American dog ticks is described. The objectives are: (1) to reevaluate the effects of zero gravity on the termination of diapause/hibernation of embryonated gypsy moth eggs, (2) to determine the effect of zero gravity on the ovipositions and subsequent hatch from engorged female American dog ticks that have been induced to diapause in the laboratory, and (3) to determine whether morphological or biochemical changes occur in the insects under examination. Results will be compared with those from a similar experiment conducted on Skylab 4

    Star formation rates and chemical abundances of emission line galaxies in intermediate-redshift clusters

    Full text link
    We examine the evolutionary status of luminous, star-forming galaxies in intermediate-redshift clusters by considering their star formation rates and the chemical and ionsiation properties of their interstellar emitting gas. Our sample consists of 17 massive, star-forming, mostly disk galaxies with M_{B}<-20, in clusters with redshifts in the range 0.31< z <0.59, with a median of =0.42. We compare these galaxies with the identically selected and analysed intermediate-redshift field sample of Mouhcine et al. (2006), and with local galaxies from the Nearby Field Galaxy Survey of Jansen et al. (2000). From our optical spectra we measure the equivalent widths of OII, Hbeta and OIII emission lines to determine diagnostic line ratios, oxygen abundances, and extinction-corrected star formation rates. The star-forming galaxies in intermediate-redshift clusters display emission line equivalent widths which are, on average, significantly smaller than measured for field galaxies at comparable redshifts. However, a contrasting fraction of our cluster galaxies have equivalent widths similar to the highest observed in the field. This tentatively suggests a bimodality in the star-formation rates per unit luminosity for galaxies in distant clusters. We find no evidence for further bimodalities, or differences between our cluster and field samples, when examining additional diagnostics and the oxygen abundances of our galaxies. This maybe because no such differences exist, perhaps because the cluster galaxies which still display signs of star-formation have recently arrived from the field. In order to examine this topic with more certainty, and to further investigate the way in which any disparity varies as a function of cluster properties, larger spectroscopic samples are needed.Comment: 10 pages, 6 figures, MNRAS in pres

    Project for the analysis of technology transfer Quarterly report, 13 Jul. - 12 Oct. 1968

    Get PDF
    Statistical characteristics of transfer data bank users, and outline of technology transfer and utilization instruction cours

    The top 5 Selling UK Energy Drinks implications for dental and general health

    Get PDF
    Aim Energy drinks are widely consumed worldwide, and are recognised for their adverse health effects, usually due to their high caffeine content. However, little is known about their impact on oral and general health . The aim of this investigation was to review the most popular energy drinks sold in the UK, for their possible effect on oral health and contribution to obesity. Materials and Method s Five drinks constituting 75% of the UK energy drinks market were purposively selected ( Lucozade, Redbull, Monster, Rockstar and Relentless) . pH and sugar content were measured and their ingredients reviewed in the context of oral and general health, focussing on dental caries and erosion and obesity . Results All 5 energy drinks investigated had pH values below the critical value (5.5) associated with dental erosion; t he lowest pH was 2.7 2 (Lucozade ), the highest pH was 3.37 (Monster). The drinks also contained excessive amounts of free sugars, ranging from 25.5g (Red Bull) to 69.2g (Rockstar). Differences in sugar content were mainly explained by portion size. Other ingredients contained within the energy drinks, caffeine and various acids are also linked to oral and general health. Conclusion Regular consumption of energy drinks could contribute to dental erosion and the development of obesity. Lucozade and Rockstar were found to potentially have the greatest impact on oral health and obesity . Achieving a healthy product by reformulation is highly unlikely due to the very high initial free sugar content. Thus health professionals need to acknowledge the popularity of these products and help their clients to reduce their use. This is the first study which compares in detail the potential oral and general health consequences of overuse of a selection of energy drinks popular in the UK

    The experimental observation of Beliaev damping in a Bose condensed gas

    Full text link
    We report the first experimental observation of Beliaev damping of a collective excitation in a Bose-condensed gas. Beliaev damping is not predicted by the Gross-Pitaevskii equation and so this is one of the few experiments that tests BEC theory beyond the mean field approximation. Measurements of the amplitude of a high frequency scissors mode, show that the Beliaev process transfers energy to a lower lying mode and then back and forth between these modes. These characteristics are quite distinct from those of Landau damping, which leads to a monotonic decrease in amplitude. To enhance the Beliaev process we adjusted the geometry of the magnetic trapping potential to give a frequency ratio of 2 to 1 between two of the scissors modes of the condensate. The ratios of the trap oscillation frequencies Ļ‰y/Ļ‰x\omega_y / \omega_x and Ļ‰z/Ļ‰x\omega_z / \omega_x were changed independently, so that we could investigate the resonant coupling over a range of conditions.Comment: 4 pages including 5 fig

    Project for the analysis of technology transfer Quarterly evaluation report, 13 Oct. - 12 Dec. 1968

    Get PDF
    Technical support package usage documentation by technology transfer analysis projec

    Cascades of multisite phosphorylation control Sic1 destruction at the onset of S phase.

    Get PDF
    Multisite phosphorylation of proteins has been proposed to transform a graded protein kinase signal into an ultrasensitive switch-like response. Although many multiphosphorylated targets have been identified, the dynamics and sequence of individual phosphorylation events within the multisite phosphorylation process have never been thoroughly studied. In Saccharomyces cerevisiae, the initiation of S phase is thought to be governed by complexes of Cdk1 and Cln cyclins that phosphorylate six or more sites on the Clb5-Cdk1 inhibitor Sic1, directing it to SCF-mediated destruction. The resulting Sic1-free Clb5-Cdk1 complex triggers S phase. Here, we demonstrate that Sic1 destruction depends on a more complex process in which both Cln2-Cdk1 and Clb5-Cdk1 act in processive multiphosphorylation cascades leading to the phosphorylation of a small number of specific phosphodegrons. The routes of these phosphorylation cascades are shaped by precisely oriented docking interactions mediated by cyclin-specific docking motifs in Sic1 and by Cks1, the phospho-adaptor subunit of Cdk1. Our results indicate that Clb5-Cdk1-dependent phosphorylation generates positive feedback that is required for switch-like Sic1 destruction. Our evidence for a docking network within clusters of phosphorylation sites uncovers a new level of complexity in Cdk1-dependent regulation of cell cycle transitions, and has general implications for the regulation of cellular processes by multisite phosphorylation

    AC electrokinetic phenomena over semiconductive surfaces: effective electric boundary conditions and their applications

    Full text link
    Electrokinetic boundary conditions are derived for AC electrokinetic (ACEK) phenomena over leaky dielectric (i.e., semiconducting) surfaces. Such boundary conditions correlate the electric potentials across the semiconductor-electrolyte interface (consisting of the electric double layer (EDL) inside the electrolyte solutions and the space charge layer (SCL) inside the semiconductors) under AC electric fields with arbitrary wave forms. The present electrokinetic boundary conditions allow for evaluation of induced zeta potential contributed by both bond charges (due to electric polarization) and free charges (due to electric conduction) from the leaky dielectric materials. Subsequently, we demonstrate the applications of these boundary conditions in analyzing the ACEK phenomena around a semiconducting cylinder. It is concluded that the flow circulations exist around the semiconducting cylinder and are shown to be stronger under an AC field with lower frequency and around a cylinder with higher conductivity.Comment: 29 pages, 4 figure

    Using schedulers to test probabilistic distributed systems

    Get PDF
    This is the author's accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s00165-012-0244-5. Copyright Ā© 2012, British Computer Society.Formal methods are one of the most important approaches to increasing the confidence in the correctness of software systems. A formal specification can be used as an oracle in testing since one can determine whether an observed behaviour is allowed by the specification. This is an important feature of formal testing: behaviours of the system observed in testing are compared with the specification and ideally this comparison is automated. In this paper we study a formal testing framework to deal with systems that interact with their environment at physically distributed interfaces, called ports, and where choices between different possibilities are probabilistically quantified. Building on previous work, we introduce two families of schedulers to resolve nondeterministic choices among different actions of the system. The first type of schedulers, which we call global schedulers, resolves nondeterministic choices by representing the environment as a single global scheduler. The second type, which we call localised schedulers, models the environment as a set of schedulers with there being one scheduler for each port. We formally define the application of schedulers to systems and provide and study different implementation relations in this setting

    Purification, growth, and characterization of Zn(x)Cd(1-x)Se crystals

    Get PDF
    The purification of starting materials which were used in the growth of Zn(x)Cd(1-x)Se (x = 0.2) single crystals using the traveling solution method (TSM) is reported. Up to 13 cm long single crystals and as grown resistivities of 6 x 10(exp 12) ohm/cm could be achieved. Infrared and Raman spectra of Zn(0.2)Cd(0.8)Se are also presented and discussed
    • ā€¦
    corecore