991 research outputs found

    Molecular dynamics simulation of the nanoindentation process in Cr/CrN and (Cr/CrN)2 thin films

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    Molecular dynamics (MD) simulations were carries out for studying the influenceof nanoindentation in the atomistic deformation mechanisms of Cr/CrN and(Cr/CrN)2 coatings with BCC and FCC crystalline structures for Cr and CrN,respectively. The Morse potential was employed in order to determine the atomicinteraction forces of the Cr-Cr and Cr-N atoms. A non-deformable potential solidsphere was implemented for determining the role of the nanoindenter. The OliverParr method (OP) was used to obtain the hardness and elastic modulus of the Cr/CrN and (Cr/CrN)2 layers, resulting in values of 18 and 20 GPa for Cr/CrN and (Cr/CrN)2, respectively. The Cheng method was used for correcting the hardness values obtained by the OP method. The Cheng correction showed higher hardness values since it avoids the influence of the scale effect. Regarding the elasticity modulus, Cr/CrN and (Cr/CrN)2 exhibited values of 217.86 GPa and 258.9 GPa, respectively. Simulations of the temperature influence on the hardness were carried out over a range of 300-1000 K. Results indicate that the hardness decreased as a function of the temperature.Fil: Amaya Roncancio, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Arias Mateus, D. F.. Universidad Católica de Pereira; ColombiaFil: Segura Giraldo, B.. Universidad Nacional de Colombia; ColombiaFil: de la Roche, J.. Universidad Nacional de Colombia; ColombiaFil: Restrepo Parra, E.. Universidad Nacional de Colombia; Colombi

    The Ursinus Weekly, March 1, 1954

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    Helfferich tells causes of delay in Union work • U.C. Supply Store resumes full operation today • Ruby show to be presented • Band starts practice for Spring concert • Composition and technique discussed by Walter Hansen • Summer School to feature single session • U. of Penn band to present concert here • Dorthee von Miller to speak at AAUW program Wed. • Spring play cast revealed; Wright, Rack in lead roles • WSGA group holds meeting • John Canady to speak at seminar sessions • WAA will present variety show Mar. 11 • Dr. Allan Rice to present Scandinavian readings • Editorials: Support the Supply; Chinese controversy • Unusual campus rules • She felt like a young colt; But looked like an old .45 • Al Sare tells of Navy life • Reporter misses big scoop; Must turn in notebook • Just plain Bill reports Belles vs. Albright game • Little Belles top Bryn Mawr • Muhlenberg decisions Bears in heartbreaker • Shreiner, Hobson, South, Rimby\u27s, Maples win • Cagemen top Fords in two overtimes • Belles down C. Hill, 57-13 • Bears top Drexel, 24-8 prior to M.A.C. wrestling • Chestnut Hill topples U.C. mermaids, 37-19 • PMC squeezes netmen to win • Snell\u27s Belles win again; Hand Wagner 55-20 losshttps://digitalcommons.ursinus.edu/weekly/1490/thumbnail.jp

    The Ursinus Weekly, March 1, 1954

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    Helfferich tells causes of delay in Union work • U.C. Supply Store resumes full operation today • Ruby show to be presented • Band starts practice for Spring concert • Composition and technique discussed by Walter Hansen • Summer School to feature single session • U. of Penn band to present concert here • Dorthee von Miller to speak at AAUW program Wed. • Spring play cast revealed; Wright, Rack in lead roles • WSGA group holds meeting • John Canady to speak at seminar sessions • WAA will present variety show Mar. 11 • Dr. Allan Rice to present Scandinavian readings • Editorials: Support the Supply; Chinese controversy • Unusual campus rules • She felt like a young colt; But looked like an old .45 • Al Sare tells of Navy life • Reporter misses big scoop; Must turn in notebook • Just plain Bill reports Belles vs. Albright game • Little Belles top Bryn Mawr • Muhlenberg decisions Bears in heartbreaker • Shreiner, Hobson, South, Rimby\u27s, Maples win • Cagemen top Fords in two overtimes • Belles down C. Hill, 57-13 • Bears top Drexel, 24-8 prior to M.A.C. wrestling • Chestnut Hill topples U.C. mermaids, 37-19 • PMC squeezes netmen to win • Snell\u27s Belles win again; Hand Wagner 55-20 losshttps://digitalcommons.ursinus.edu/weekly/1490/thumbnail.jp

    Biharmonic pattern selection

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    A new model to describe fractal growth is discussed which includes effects due to long-range coupling between displacements uu. The model is based on the biharmonic equation 4u=0\nabla^{4}u =0 in two-dimensional isotropic defect-free media as follows from the Kuramoto-Sivashinsky equation for pattern formation -or, alternatively, from the theory of elasticity. As a difference with Laplacian and Poisson growth models, in the new model the Laplacian of uu is neither zero nor proportional to uu. Its discretization allows to reproduce a transition from dense to multibranched growth at a point in which the growth velocity exhibits a minimum similarly to what occurs within Poisson growth in planar geometry. Furthermore, in circular geometry the transition point is estimated for the simplest case from the relation rL/e1/2r_{\ell}\approx L/e^{1/2} such that the trajectories become stable at the growing surfaces in a continuous limit. Hence, within the biharmonic growth model, this transition depends only on the system size LL and occurs approximately at a distance 60%60 \% far from a central seed particle. The influence of biharmonic patterns on the growth probability for each lattice site is also analysed.Comment: To appear in Phys. Rev. E. Copies upon request to [email protected]

    SPIDER VII - Revealing the Stellar Population Content of Massive Early-type Galaxies out to 8Re

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    Radial trends of stellar populations in galaxies provide a valuable tool to understand the mechanisms of galaxy growth. In this paper, we present the first comprehensive analysis of optical-optical and optical-NIR colours, as a function of galaxy mass, out to the halo region (8Re) of early-type galaxies (ETGs). We select a sample of 674 massive ETGs (M*>3x10^10MSun) from the SDSS-based SPIDER survey. By comparing with a large range of population synthesis models, we derive robust constraints on the radial trends in age and metallicity. Metallicity is unambiguously found to decrease outwards, with a measurable steepening of the slope in the outer regions (Re<R<8Re). The gradients in stellar age are found to be more sensitive to the models used, but in general, the outer regions of ETGs feature older populations compared to the cores. This trend is strongest for the most massive galaxies in our sample (M*>10^11MSun). Furthermore, when segregating with respect to large scale environment, the age gradient is more significant in ETGs residing in higher density regions. These results shed light on the processes leading from the formation of the central core to the growth of the stellar envelope of massive galaxies. The fact that the populations in the outer regions are older and more metal-poor than in the core suggests a process whereby the envelope of massive galaxies is made up of accreted small satellites (i.e. minor mergers) whose stars were born during the first stages of galaxy formation.Comment: 20 pages, 13 figures, 10 tables. Accepted for publication in MNRA

    Spectroscopic bulge-disc decomposition: a new method to study the evolution of lenticular galaxies

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    A new method for spectroscopic bulge-disc decomposition is presented, in which the spatial light profile in a two-dimensional spectrum is decomposed wavelength-by-wavelength into bulge and disc components, allowing separate one-dimensional spectra for each component to be constructed. This method has been applied to observations of a sample of nine S0s in the Fornax Cluster in order to obtain clean high-quality spectra of their individual bulge and disc components. So far this decomposition has only been fully successful when applied to galaxies with clean light profiles, consequently limiting the number of galaxies that could be separated into bulge and disc components. Lick index stellar population analysis of the component spectra reveals that in those galaxies where the bulge and disc could be distinguished, the bulges have systematically higher metallicities and younger stellar populations than the discs. This correlation is consistent with a picture in which S0 formation comprises the shutting down of star formation in the disc accompanied by a final burst of star formation in the bulge. The variation in spatial-fit parameters with wavelength also allows us to measure approximate colour gradients in the individual components. Such gradients were detected separately in both bulges and discs, in the sense that redder light is systematically more centrally concentrated in all components. However, a search for radial variations in the absorption line strengths determined for the individual components revealed that they are absent from the vast majority of S0 discs and bulges. The absence of gradients in line indices for most galaxies implies that the colour gradient cannot be attributed to age or metallicity variations, and is therefore most likely associated with varying degrees of obscuration by dust.Comment: 10 pages, 10 figures, 1 table, accepted for publication in MNRA

    Primary Cilia Mediate Diverse Kinase Inhibitor Resistance Mechanisms in Cancer.

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    Primary cilia are microtubule-based organelles that detect mechanical and chemical stimuli. Although cilia house a number of oncogenic molecules (including Smoothened, KRAS, EGFR, and PDGFR), their precise role in cancer remains unclear. We have interrogated the role of cilia in acquired and de novo resistance to a variety of kinase inhibitors, and found that, in several examples, resistant cells are distinctly characterized by an increase in the number and/or length of cilia with altered structural features. Changes in ciliation seem to be linked to differences in the molecular composition of cilia and result in enhanced Hedgehog pathway activation. Notably, manipulating cilia length via Kif7 knockdown is sufficient to confer drug resistance in drug-sensitive cells. Conversely, targeting of cilia length or integrity through genetic and pharmacological approaches overcomes kinase inhibitor resistance. Our work establishes a role for ciliogenesis and cilia length in promoting cancer drug resistance and has significant translational implications.This research was partly funded by the Institute of Cancer Research and by grants from Sarcoma UK (to B.E.T. [14.2014] and P.H.H. [3.2014]), Kent Cancer Trust (to M.M.), Hilfe fuer Krebskranke Kinder Frankfurt e.V. and Frankfurter Stiftung fuer Krebskranke Kinder (to J.C.), CRUK-CI Core Grant (C14303/A17197), and S.H.D. Fellowship (Wellcome Trust/Royal Society [107609]) (to M.D.R.). B.E.T. was supported by an ICR fellowship

    New constraints on the HR 8799 planetary system from mid-infrared direct imaging

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    Direct imaging is a tried and tested method of detecting exoplanets in the near-infrared (IR), but has so far not been extended to longer wavelengths. New data at mid-IR wavelengths (8-20 μm) can provide additional constraints on planetary atmospheric models. We use the VLT Imager and Spectrometer for the mid-IR (VISIR) instrument on the VLT to detect or set stringent limits on the 8.7 μm flux of the four planets surrounding HR 8799, and to search for additional companions. We use a novel circularized point spread function subtraction technique to reduce the stellar signal and obtain instrument limited background levels and obtain optimal flux limits. The BT SETTL isochrones are then used to determine the resulting mass limits. We find flux limits between 0.7 and 3.3 mJy for the J8.9 flux of the different planets at better than 5σ level and derive a new mass limit of 30 MJup for any objects beyond 40 au. While this work has not detected planets in the HR 8799 system at 8.7 μm, it has found that an instrument with the sensitivity of VISIR is sufficient to detect at least four known hot planets around close stars, including β Pictoris b (1700 K, 19 pc), with more than 5σ certainty in 10 h of observing time in the mid-IR

    Estimating a threshold price for CO2 emissions of buildings to improve their energy performance level. Case study of a new Spanish home

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    Energy consumption in homes produces CO2. In many countries, building regulations are being set to enable energy efficiency performance levels to be issued. In Spain, there is a regulated procedure to certify the energy performance of buildings according to their CO2 emissions. Consequently, some software tools have been design to simulate buildings and to obtain their energy consumption and CO2 emissions. In this paper the investment, maintenance and energy consumption costs are calculated for different energy performance levels and for various climatic zones, in a single-family home. According to the results, more energy efficient buildings imply higher construction and maintenance costs, which are not compensated by lower energy costs. Therefore, under current conditions, economic criteria do not support the improvement of the energy efficiency of a dwelling. Among the possible measures to promote energy efficiency, a price on CO2 emissions is to be suggested, including the social cost in the analysis. For this purpose, the cost-optimal methodology is used. In different scenarios for the discount rate y energy prices, various prices for CO2 are obtained, depending on the climatic zone and energy performance level.Ruá Aguilar, MJ.; Guadalajara Olmeda, MN. (2015). Estimating a threshold price for CO2 emissions of buildings to improve their energy performance level. Case study of a new Spanish home. Energy Efficiency. 8(2):183-203. doi:10.1007/s12053-014-9286-2S18320382AICIA. (2009). Escala de calificación energética. Edificios de nueva construcción. Madrid: Instituto para la Diversificación y Ahorro de la Energía, Ministerio de Industria, Turismo y Comercio.Al-Homoud, M. S. (2005). Performance characteristics and practical applications of common building thermal insulation materials. Building and Environment, 40(3), 353–360.Amecke, H. 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    Galaxy evolution by color-log(n) type since redshift unity in the Hubble Ultra Deep Field

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    We explore the use of the color-log(n) plane (where n is the global Sersic index) as a tool for subdividing the high redshift galaxy population in a physically-motivated manner. Using a series of volume-limited samples out to z=1.5 in the Hubble Ultra Deep Field (UDF) we confirm the correlation between color-log(n) plane position and visual morphology observed locally and in other high redshift studies in the color and/or structure domain. Via comparison to a low redshift sample from the Millennium Galaxy Catalogue we quantify evolution by color-log(n) type, accounting separately for the specific selection and measurement biases against each. Specifically, we measure decreases in B-band surface brightness of 1.57 +/- 0.22 mag/sq.arcsec and 1.65 +/- 0.22 mag/sq.arcsec for `blue, diffuse' and `red, compact' galaxies respectively between redshift unity and the present day.Comment: 12 pages, 6 figures, to be published in A&A (accepted 29/10/08
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