4,818 research outputs found

    James Cook Maritime Scientist, by Tom and Cordelia Stamp

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    Constraints on DD Dimensional Warped Spaces

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    In order to investigate the phenomenological implications of allowing gauge fields to propagate in warped spaces of more than five dimensions, we consider a toy model of a space warped by the presence of a anisotropic bulk cosmological constant. After solving the Einstein equation, three classes of solutions are found, those in which the additional (D>5D>5) dimensions are growing, shrinking or remaining constant. It is found that gauge fields propagating in these spaces have a significantly different Kaluza Klein (KK) mass spectrum and couplings from that of the Randall and Sundrum model. This leads to a greatly reduced lower bound on the KK scale, arising from electroweak constraints, for spaces growing towards the IR brane.Comment: 6 pages, 5 figures PASCOS2010 International Symposium proceedin

    Structure, phase behavior and inhomogeneous fluid properties of binary dendrimer mixtures

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    The effective pair potentials between different kinds of dendrimers in solution can be well approximated by appropriate Gaussian functions. We find that in binary dendrimer mixtures the range and strength of the effective interactions depend strongly upon the specific dendrimer architecture. We consider two different types of dendrimer mixtures, employing the Gaussian effective pair potentials, to determine the bulk fluid structure and phase behavior. Using a simple mean field density functional theory (DFT) we find good agreement between theory and simulation results for the bulk fluid structure. Depending on the mixture, we find bulk fluid-fluid phase separation (macro-phase separation) or micro-phase separation, i.e., a transition to a state characterized by undamped periodic concentration fluctuations. We also determine the inhomogeneous fluid structure for confinement in spherical cavities. Again, we find good agreement between the DFT and simulation results. For the dendrimer mixture exhibiting micro-phase separation, we observe rather striking pattern formation under confinement.Comment: 8 pages, 10 figure

    An evaluation of Skylab (EREP) remote sensing techniques applied to investigations of crustal structure

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    The author has identified the following significant results. Film positives (70mm) from all six S190A multispectral photographic camera stations for any one scene can be registered and analyzed in a color additive viewer. Using a multispectral viewer, S190A and B films can be projected directly onto published geologic and topographic maps at scales as large as 1:62,500 and 1:24,000 without significant loss of detail. S190A films and prints permit the detection of faults, fractures, and other linear features not visible in any other space imagery. S192 MSS imagery can be useful for rock-type discrimination studies and delineation of linear patterns and arcuate anomalies. Anomalous color reflectances and arcuate color patterns revealed mineralized zones, copper deposits, vegetation, and volcanic rocks in various locations such as Panamint Range (CA), Greenwater (Death Valley), Lava Mountains (CA), northwestern Arizona, and Coso Hot Springs (CA)

    Revealing the nebular properties and Wolf-Rayet population of IC10 with Gemini/GMOS

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    We present a deep imaging and spectroscopic survey of the Local Group irregular galaxy IC10 using Gemini North and GMOS to unveil its global Wolf-Rayet (WR) population. We obtain a star formation rate (SFR) of 0.045 ± 0.023 M⊙yr−1, for IC10 from the nebular Hα luminosity, which is comparable to the SMC. We also present a revised nebular oxygen abundance of log(O/H) + 12 = 8.40 ± 0.04, comparable to the LMC. It has previously been suggested that for IC10 to follow the WR subtype-metallicity dependance seen in other Local Group galaxies, a large WN population awaits discovery. Our search revealed 3 new WN stars, and 6 candidates awaiting confirmation, providing little evidence to support this claim. The new global WR star total of 29 stars is consistent with the LMC population when scaled to the reduced SFR of IC10. For spectroscopically confirmed WR stars, the WC/WN ratio is lowered to 1.0, however including all potential candidates, and assuming those unconfirmed to be WN stars, would reduce the ratio to ∼0.7. We attribute the high WC/WN ratio to the high star formation surface density of IC10 relative to the Magellanic Clouds, which enhances the frequency of high mass stars capable of producing WC stars

    London’s rivers: a collection of landscape drawings

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    Textos en inglés, español y catalán[EN]The 22 drawings that form the series London’s Rivers were designed in Elche (Spain) and London between January and July 2012 and were shown at the Aifos Room of the University of Alicante between February and March 2013, in an exhibition entitled Gardens Materials Landscapes. They were published in a CD-ROM, in digital format. The technique used is acrylic on paper Canson Figueras acid free, 290 gr / m2; the size of each design is 190 x 240 mm. Additionally, 20 further drawings are included in an Addendum. These were designed in the winter and spring of 2014, and are by way of thanks to those friends whose texts accompany the original series London’s Rivers (2012) published here. The technique used is acrylic on canvas sketch pads made from cotton fabric, 380 gr / m2; the size of each design is 210 x 297 mm

    Graphical technique for identifying a monotonic variance stabilizing transformation for absolute gene intensity signals

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    BACKGROUND: The usefulness of log(2 )transformation for cDNA microarray data has led to its widespread application to Affymetrix data. For Affymetrix data, where absolute intensities are indicative of number of transcripts, there is a systematic relationship between variance and magnitude of measurements. Application of the log(2 )transformation expands the scale of genes with low intensities while compressing the scale of genes with higher intensities thus reversing the mean by variance relationship. The usefulness of these transformations needs to be examined. RESULTS: Using an Affymetrix GeneChip(® )dataset, problems associated with applying the log(2 )transformation to absolute intensity data are demonstrated. Use of the spread-versus-level plot to identify an appropriate variance stabilizing transformation is presented. For the data presented, the spread-versus-level plot identified a power transformation that successfully stabilized the variance of probe set summaries. CONCLUSION: The spread-versus-level plot is helpful to identify transformations for variance stabilization. This is robust against outliers and avoids assumption of models and maximizations

    Physicochemical Properties and Catalytic Behavior of the Molecular Sieve SSZ-70

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    SSZ-70 is synthesized using 1,3-bis(isobutyl)imidazolium, 1,3-bis(cyclohexyl)imidazolium, and 1,3-bis(cycloheptyl)imidazolium structure directing agents (SDAs), and the solids obtained are characterized by powder X-ray diffraction (XRD), ^(29)Si magic angle spinning nuclear magnetic resonance (MAS NMR), electron microscopy, nitrogen and hydrocarbon adsorption, and thermogravimetric analyses. The physicochemical properties of SSZ-70 show that it is a new molecular sieve that has similarities to MWW-type materials. The catalytic behavior of SSZ-70 is evaluated through the use of the constraint index (CI) test. Distinct differences in the reactivity between Al-SSZ-70 and SSZ-25 (MWW) are observed and are the consequences of the structural differences between these two molecular sieves

    Note on the hydrodynamic description of thin nematic films: strong anchoring model

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    We discuss the long-wave hydrodynamic model for a thin film of nematic liquid crystal in the limit of strong anchoring at the free surface and at the substrate. We rigorously clarify how the elastic energy enters the evolution equation for the film thickness in order to provide a solid basis for further investigation: several conflicting models exist in the literature that predict qualitatively different behaviour. We consolidate the various approaches and show that the long-wave model derived through an asymptotic expansion of the full nemato-hydrodynamic equations with consistent boundary conditions agrees with the model one obtains by employing a thermodynamically motivated gradient dynamics formulation based on an underlying free energy functional. As a result, we find that in the case of strong anchoring the elastic distortion energy is always stabilising. To support the discussion in the main part of the paper, an appendix gives the full derivation of the evolution equation for the film thickness via asymptotic expansion
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