9,450 research outputs found

    ISOGAL Survey of Baade's Windows in the Mid-infrared

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    The ISOGAL mid-infrared survey of areas close to the Galactic Plane aims to determine their stellar content and its possible bearing on the history of the Galaxy. The NGC6522 and Sgr I Baade's Windows of low obscuration towards the inner parts of the Bulge represent ideal places in which to calibrate and understand the ISOGAL colour-magnitude diagrams. The survey observations were made with the ISOCAM instrument of the ISO satellite. The filter bands chosen were LW2(~7 microns) and LW3(~15 microns). The results presented here show that most of the detected objects are late M-type giants on the AGB, with a cut-off for those earlier than M3-M4. The most luminous members of these two Bulge fields at 7 microns are the Mira variables. However, it is evident that they represent the end of a sequence of increasing 15 micron dust emission which commences with M giants of earlier sub-type. In observations of late-type giants the ISOCAM 15 micron band is mainly sensitive to the cool silicate or aluminate dust shells which overwhelm the photospheric emission. However, in ordinary M-giant stars, the 7 micron band is not strongly affected by dust emission and may be influenced instead by absorption. The nu2 band of water at 6.25 microns and the SiO fundamental at 7.9 microns are likely contribitors to this effect. A group of late M stars has been found which vary little or not at all but have infrared colours typical of well-developed dust shells. Their luminosities are similar to those of 200-300 day Miras but they have slightly redder [7]-[15] colours which form an extension of the ordinary M giant sequence. The Mira dust shells show a mid-infrared [7]-[15] colour-period relation. ca 700 days.Comment: 13 pages 15 figure

    Diffraction-Limited Imaging and Photometry of NGC 1068

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    The nearby Seyfert 2 Galaxy NGC 1068 was observed with speckle imaging techniques in the near-infrared H-band (1.6 microns) at the Hale 200-inch Telescope and K-band (2.2 microns) at the 10 m Keck I Telescope. Images with diffraction limited or near-diffraction limited resolutions of 0.''05 - 0.''1 were obtained and used to search for structure in the nuclear region. Images of the nucleus of NGC 1068 reveal an extended region of emission which accounts for nearly 50% of the nuclear flux at K-band. This region extends 10 pc on either side of an unresolved point source nucleus which is at most, 0.''02 or 1.4 pc in size. Both the point source and the newly imaged extended emission are very red, with identical H-K colors corresponding to a color temperature of 800 K. While the point source is of a size to be consistent with grains in thermal equilibrium with the nuclear source, the extended emission is not. It must consist either of nuclear emission which has been reflected off an extended dusty disk or of small grains raised to transiently high temperatures by reflected UV photons.Comment: accepted to AJ, AAS LaTeX and epsfig, 22 pages incl. 5 ps figure

    Projectile Δ\Delta Excitations in p(p,n)Nπp(p,n)N\pi Reactions

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    It has recently been proven from measurements of the spin-transfer coefficients DxxD_{xx} and DzzD_{zz} that there is a small but non-vanishing ΔS=0\Delta S=0 component σ0\sigma_{0}, in the inclusive p(p,n)Nπp(p,n)N\pi\, reaction cross section σ\sigma\,. It is shown that the dominant part of the measured σ0\sigma_{0} can be explained in terms of the projectile Δ\Delta excitation mechanism. An estimate is further made of contributions to σ0\sigma_{0} from s-wave rescattering process. It is found that s-wave rescattering contribution is much smaller than the contribution coming from projectile Δ\Delta excitation mechanism. The addition of s-wave rescattering contribution to the dominant part, however, improves the fit to the data.Comment: 9 pages, Revtex, figures can be obtained upon reques

    Transforming Sustainable Value in the Construction Industry – The role of Social Movements

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    Projects pursuing the balance of economic, ecological, and social aspects are being increasingly implemented by the construction industry. This shift represents a paradigm change and evidences new values being acknowledged within the sector. Concurrently, construction scholars tend to emphasize the creation, retention and addition of value, focusing mostly on costs and client deliverables. However, less attention is paid to the process of value change, specifically one that focuses on alternative stakeholders, such as Social Movements. We employ Social Movement theory to comprehend how these organizations affect the notion of value and value change in this industry. Their role is accentuated as a source for a value paradigm change in the form of institutional pressures that shape the values of other stakeholders of the construction industry. These pressures elicit a response in the form of a broader incorporation of sustainable practices amongst construction projects, which effectively alters the industry’s notion of value. Additionally, we showcase a theoretical model that describes the pressure channels originated by Social Movements and their process mechanism affecting the construction industry

    Noise Effects on the Complex Patterns of Abnormal Heartbeats

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    Patients at high risk for sudden death often exhibit complex heart rhythms in which abnormal heartbeats are interspersed with normal heartbeats. We analyze such a complex rhythm in a single patient over a 12-hour period and show that the rhythm can be described by a theoretical model consisting of two interacting oscillators with stochastic elements. By varying the magnitude of the noise, we show that for an intermediate level of noise, the model gives best agreement with key statistical features of the dynamics.Comment: 4 pages, 4 figures, RevTe

    Schwarzschild Atmospheric Processes: A Classical Path to the Quantum

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    We develop some classical descriptions for processes in the Schwarzschild string atmosphere. These processes suggest relationships between macroscopic and microscopic scales. The classical descriptions developed in this essay highlight the fundamental quantum nature of the Schwarzschild atmospheric processes.Comment: to appear in Gen. Rel. Gra

    As indicações geográficas como estratégia mercadológica para vinhos.

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    Este texto tem como objetivo principal analisar, em termos de estratégia mercadológica, as indicações geográficas (IGs) como instrumento de agregação de valor para o agronegócio brasileiro. Além de analisar a evolução do conceito de indicações geográficas no Brasil, na França e em outros países, este trabalho discute os aspectos mercadológicos desse mecanismo da propriedade intelectual. A fim de ilustrar e sustentar a discussão, apresentam-se os resultados de um estudo das IGs, levando-se em conta a percepção das vinícolas brasileiras e de um nicho do mercado consumidor de vinhos do Distrito Federal, Brasil. Neste estudo, foi observado que as IGs são um fator de diferenciação mercadológica nesse nicho de mercado e, também, uma característica relevante que agrega valor aos vinho s. No mínimo 57% dos consumidores pesquisados estariam dispostos a pagar mais por vinhos que possuíssem uma IG. Por sua vez, as vinícolas brasileiras estão cientes da importância mercadológica das IGs, já que 83% das empresas pesquisadas têm tomado iniciativa com esse propósito. Exceto em alguns casos, observou-se o quão distintas são as percepções dos atores da cadeia pesquisada em relação aos fatores mercadológicos estudados, principalmente sobre a IG. Por fim, são tecidas considerações a respeito das indicações geográficas como uma oportunidade de agregação de valor para o agronegócio brasileiro, sugerindo-se que a construção de uma estratégia mercadológica baseada nas indicações geográficas, tendo como público-alvo consumidores que buscam qualidade superior, pode ser comercialmente positiva para determinados produtores e regiões do agronegócio nacional

    Research on nonlinear optical materials: an assessment. IV. Photorefractive and liquid crystal materials

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    This panel considered two separate subject areas: photorefractive materials used for nonlinear optics and liquid crystal materials used in light valves. Two related subjects were not considered due to lack of expertise on the panel: photorefractive materials used in light valves and liquid crystal materials used in nonlinear optics. Although the inclusion of a discussion of light valves by a panel on nonlinear optical materials at first seems odd, it is logical because light valves and photorefractive materials perform common functions

    Massive Stars in the Quintuplet Cluster

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    We present near-infrared photometry and K-band spectra of newly-identified massive stars in the Quintuplet Cluster, one of the three massive clusters projected within 50 pc of the Galactic Center. We find that the cluster contains a variety of massive stars, including more unambiguously identified Wolf-Rayet stars than any cluster in the Galaxy, and over a dozen stars in earlier stages of evolution, i.e., LBV, Ofpe/WN9, and OB supergiants. One newly identified star is the second ``Luminous Blue Variable'' in the cluster, after the ``Pistol Star.'' Given the evolutionary stages of the identified stars, the cluster appears to be about 4 \pm 1 Myr old, assuming coeval formation. The total mass in observed stars is \sim 10^3 \Msun, and the implied mass is \sim 10^4 \Msun, assuming a lower mass cutoff of 1 \Msun and a Salpeter initial mass function. The implied mass density in stars is at least a few thousand \Msun pc^{-3}. The newly-identified stars increase the estimated ionizing flux from this cluster by about an order of magnitude with respect to earlier estimates, to 10^{50.9} photons/s, or roughly what is required to ionize the nearby ``Sickle'' HII region (G0.18 - 0.04). The total luminosity from the massive cluster stars is 107.5\approx 10^{7.5} \Lsun, enough to account for the heating of the nearby molecular cloud, M0.20 - 0.033. We propose a picture which integrates most of the major features in this part of the sky, excepting the non-thermal filaments. We compare the cluster to other young massive clusters and globular clusters, finding that it is unique in stellar content and age, except, perhaps, for the young cluster in the central parsec of the Galaxy. In addition, we find that the cluster is comparable to small ``super star clusters.'

    Optimal synchronization of directed complex networks

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    We study optimal synchronization of networks of coupled phase oscillators. We extend previous theory for optimizing the synchronization properties of undirected networks to the important case of directed networks. We derive a generalized synchrony alignment function that encodes the interplay between network structure and the oscillators' natural frequencies and serves as an objective measure for the network's degree of synchronization. Using the generalized synchrony alignment function, we show that a network's synchronization properties can be systematically optimized. This framework also allows us to study the properties of synchrony-optimized networks, and in particular, investigate the role of directed network properties such as nodal in- and out-degrees. For instance, we find that in optimally rewired networks the heterogeneity of the in-degree distribution roughly matches the heterogeneity of the natural frequency distribution, but no such relationship emerges for out-degrees. We also observe that a network's synchronization properties are promoted by a strong correlation between the nodal in-degrees and the natural frequencies of oscillators, whereas the relationship between the nodal out-degrees and the natural frequencies has comparatively little effect. This result is supported by our theory, which indicates that synchronization is promoted by a strong alignment of the natural frequencies with the left singular vectors corresponding to the largest singular values of the Laplacian matrix
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