9,808 research outputs found

    An assessment of warm fog: Nucleation, control, and recommended research

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    A state-of-the-art survey is given of warm fog research which has been performed up to, and including, 1974. Topics covered are nucleation, growth, coalescence, fog structures and visibility, effects of surface films, drop size spectrum, optical properties, instrumentation, liquid water content, condensation nuclei. Included is a summary of all reported fog modification experiments. Additional data is provided on air flow, turbulence, a summary of recommendations on instruments to be developed for determining turbulence, air flow, etc., as well as recommendations of various fog research tasks which should be performed for a better understanding of fog microphysics

    Wind shear and wet and dry thermodynamic indices as predictors of thunderstorm motion and severity and application to the AVE 4 experimental data

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    Two types of parameters are computed and mapped for use in assessing their individual merits as predictors of occurrence and severity of thunderstorms. The first group is comprised of equivalent potential temperature, potential temperature, water vapor mixing ratio, and wind speed. Equivalent potential temperature maxima and strong gradients of equivalent potential temperature at the surface correlate well with regions of thunderstorm activity. The second type, comprised of the energy index, shear index, and energy shear index, incorporates some model dynamics of thunderstorms, including nonthermodynamic forcing. The energy shear index is found to improve prediction of tornadic and high-wind situations slightly better than other indices. It is concluded that further development and refinement of nonthermodynamic aspects of predictive indices are definitely warranted

    Toward using an oxidatively damaged plasmid as an intra- and inter-laboratory standard for ancient DNA studies

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    The following paper was originally presented by Dr Thomas H. Loy at the 6th International Conference on Ancient DNA and Associated Biomolecules held in Israel, July 2002. It is included here with editorial and formatting changes with the intention of demonstrating the passion and lateral thinking that underpinned Tomï½s approach to the field of Molecular Archaeology. The paper represents research from three honours projects conducted during the late 1990s and early 2000s. Building a modern model for ancient DNA that could be used during routine procedures was a concept that Tom had long held as an important step forward for the burgeoning discipline. With the equipment and technology that was available at the time, the Damaged Plasmid Model concept was completely viable and worthy of detailed validation. As with all historical accounts, an understanding of more recent developments in molecular techniques and equipment will highlight the need for considerable optimisation of the model before it can be used as an interlaboratory standard for ancient DN

    High Amplitude Short Time Excitation: A Method to Form and Detect Low Mass Product Ions in a Quadrupole Ion Trap Mass Spectrometer

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    Collision induced dissociation (CID) in a quadrupole ion trap mass spectrometer using the conventional 30 ms activation time is compared with high amplitude short time excitation (HASTE) CID using 2 ms and 1 ms activation times. As a result of the shorter activation times, dissociation of the parent ions using the HASTE CID technique requires resonance excitation voltages greater than conventional CID. After activation, the rf trapping voltage is lowered to allow product ions below the low mass cut-off to be trapped. The HASTE CID spectra are notably different from those obtained using conventional CID and can include product ions below the low mass cut-off for the parent ions of interest. The MS/MS efficiencies of HASTE CID are not significantly different when compared with the conventional 30 ms CID. Similar results were obtained with a two-dimensional (linear) ion trap and a three-dimensional ion trap

    Nano-scale mechanical probing of supported lipid bilayers with atomic force microscopy

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    We present theory and experiments for the force-distance curve F(z0)F(z_0) of an atomic force microscope (AFM) tip (radius RR) indenting a supported fluid bilayer (thickness 2d2d). For realistic conditions the force is dominated by the area compressibility modulus κA\kappa_A of the bilayer, and, to an excellent approximation, given by F=πκARz02/(2dz0)2F= \pi \kappa_A R z_0^2/(2d-z_0)^2. The experimental AFM force curves from coexisting liquid ordered and liquid disordered domains in 3-component lipid bilayers are well-described by our model, and provides κA\kappa_A in agreement with literature values. The liquid ordered phase has a yield like response that we model by hydrogen bond breaking.Comment: 6 pages, 6 figures, accepted for publication in Physical Review

    Adhesive Joining of Composite Laminates Using Epoxy Resins with Stoichiometric Offset

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    Polymer matrix composites are used in high performance structures because of their excellent specific strength, toughness and stiffness along the fiber. To realize the full performance advantages of composites, complex, built-up structures must be assembled with adhesive, but uncertainty in bond strength requires manufacturers to install bolts or other crack arrest features to ensure safety in critical applications. The inherent uncertainty in adhesive bonds stems from the material discontinuity at the composite-to-adhesive interfaces, which are susceptible to contamination. In contrast, composites made by co-curing, although limited in size and complexity, result in predictable structures that may be certifiable for commercial aviation with reduced dependence on redundant load paths.1 The pro-posed technology uses a stoichiometric offset of the hardener-to-epoxy ratio on the faying surfaces of laminates. Assembly of the components in a subsequent secondary-co-cure process results in a joint with no material discontinuities

    The INTEGRAL/SPI response and the Crab observations

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    The Crab region was observed several times by INTEGRAL for calibration purposes. This paper aims at underlining the systematic interactions between (i) observations of this reference source, (ii) in-flight calibration of the instrumental response and (iii) the development and validation of the analysis tools of the SPI spectrometer. It first describes the way the response is produced and how studies of the Crab spectrum lead to improvements and corrections in the initial response. Then, we present the tools which were developed to extract spectra from the SPI observation data and finally a Crab spectrum obtained with one of these methods, to show the agreement with previous experiments. We conclude with the work still ahead to understand residual uncertainties in the response.Comment: 4 pages, 4 figures, Proc. of the 5th INTEGRAL Workshop (Feb. 16-20 2004), to be published by ES

    Preliminary investigation of Phase Doppler derived flux measurements in a wind tunnel for the sampling of orchard spray drift

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    Air-assisted spray equipment used for horticultural cropping systems depend on high air velocities to project the spray as well as to open the canopy for greater droplet penetration and deposition. However, these sprayer-types are also at a heightened risk for spray drift as they possess the potential to place drift prone droplets in the atmosphere where they can be carried to off-target locations. Unfortunately, quantifying these droplets can be difficult and expensive using samplers such as high-volume air samplers, rotating rods and strings. However, while these measuring techniques may give some idea of flux, no particle information can be gained which is imperative to predicting the mass which may be the most prone to drift. In wind-tunnels and field studies, polyester and nylon strings have proven to be an efficient collecting surface. Therefore, it was the objective of this study to assess the potential for the use of a novel, field grade Phase Doppler Interferometer (PDI) as a replacement for strings as a sampler for driftable mass for orchard type sprayers

    Inclusive Masculinity and Facebook Photographs Among Early Emerging Adults at a British University

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    Central to debates about the construction of masculinity in sociology is the influence of culture and what constitutes acceptable displays of masculinity. This article adopts a novel approach in examining this question. It adopts a summative content analysis, combined with a semiotic analysis, of 1,100 Facebook photographs, in order to explore the underlying meanings within the photos and the performances of masculinity. Facebook photographs from 44, straight, White, male, early emerging adults attending the same university are used as a representation of an individual’s ideal self. These are then analyzed in order to determine the behaviors endorsed by peer culture. It was found that the sample overwhelmingly adopted inclusive behaviors (including homosocial tactility, dancing, and kissing each other), and inclusive masculinity theory was utilized to contextualize participants’ constructions of masculinity. Thus, this research shows that emerging adult males at this university construct their masculine identities away from previous orthodox archetypes. It is argued that the reducing importance of gendered behavior patterns may represent an adoption of what are perceived as wider cultural norms and act as a symbol of adulthood to these early emerging adults
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