3,524 research outputs found

    Editorial

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    Bismuth incorporation and the role of ordering in GaAsBi/GaAs structures

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    The structure and composition of single GaAsBi/GaAs epilayers grown by molecular beam epitaxy were investigated by optical and transmission electron microscopy techniques. Firstly, the GaAsBi layers exhibit two distinct regions and a varying Bi composition profile in the growth direction. In the lower (25 nm) region, the Bi content decays exponentially from an initial maximum value, while the upper region comprises an almost constant Bi content until the end of the layer. Secondly, despite the relatively low Bi content, CuPtB-type ordering was observed both in electron diffraction patterns and in fast Fourier transform reconstructions from high-resolution transmission electron microscopy images. The estimation of the long-range ordering parameter and the development of ordering maps by using geometrical phase algorithms indicate a direct connection between the solubility of Bi and the amount of ordering. The occurrence of both phase separation and atomic ordering has a significant effect on the optical properties of these layers

    Del Sistema al Prototipo y viceversa (el caso de la GBH + INVISO)

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    Main subject of this article is showing how most of famous manufacturing houses of XX Century are not only single prototypes, but they really are part of general system from upper level (system they want testing). Also, we can prove how this kind of generation don’t running “from Prototype to the System” (by single juxtaposition of the model to increase scale). On contrary way this prototypes are the result of inverse procedure (after, they will be as feed-back to refine start system). To this purpose the article show 5 historic cases as background within this behavior line, and INVISO winner and GBHouse are analyze most deep. From this studio we can get some conclusion about relation between “General Theory of Systems” and “open industrialization” premises give to S.3c (System constructed by compatibles components): as flexibility or recycling, and how we can get it through proving procedures.La mayoría de las viviendas industriales famosas del SXX no son solo eso (prototipos individuales): forman parte de un sistema general de grado muy superior para ponerlo a prueba. Se demuestra en este artículo como el recorrido en esta clase de concepción productiva no se efectúa “desde el prototipo al sistema” por una simple adición del modelo; al contrario, estos prototipos resultan del camino inverso, para luego sí, servir como feed-back. Se muestran 5 antecedentes históricos dentro de este recorrido, y se analizan más a fondo el Primer premio del concurso INVIso y la casa GBH. De su estudio se derivan algunas conclusiones en cuanto a la relación entre la Teoría General de Sistemas y las premisas que la Industrialización Abierta confiere a los Sistemas construidos a partir de componentes compatibles (S.3c), como la flexibilidad, o el reciclaje, y la manera de conseguir que estas se cumplan mediante procedimientos probados

    An infinite family of magnetized Morgan-Morgan relativistic thin disks

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    Applying the Horsk\'y-Mitskievitch conjecture to the empty space solutions of Morgan and Morgan due to the gravitational field of a finite disk, we have obtained the corresponding solutions of the Einstein-Maxwell equations. The resulting expressions are simply written in terms of oblate spheroidal coordinates and the solutions represent fields due to magnetized static thin disk of finite extension. Now, although the solutions are not asymptotically flat, the masses of the disks are finite and the energy-momentum tensor agrees with the energy conditions. Furthermore, the magnetic field and the circular velocity show an acceptable physical behavior.Comment: Submitted to IJTP. This paper is a revised and extended version of a paper that was presented at arXiv:1006.203

    Resonance phenomena of a solitonlike extended object in a bistable potential

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    We investigate the dynamics of a soliton that behaves as an extended particle. The soliton motion in an effective bistable potential can be chaotic in a similar way as the Duffing oscillator. We generalize the concept of geometrical resonance to spatiotemporal systems and apply it to design a nonfeedback mechanism of chaos control using localized perturbations.We show the existence of solitonic stochastic resonance.Comment: 3 postscript figure

    3D numerical model of the Omega Nebula (M17): simulated thermal X-ray emission

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    We present 3D hydrodynamical simulations of the superbubble M17, also known as the Omega nebula, carried out with the adaptive grid code yguazu'-a, which includes radiative cooling. The superbubble is modelled considering the winds of 11 individual stars from the open cluster inside the nebula (NGC 6618), for which there are estimates of the mass loss rates and terminal velocities based on their spectral types. These stars are located inside a dense interstellar medium, and they are bounded by two dense molecular clouds. We carried out three numerical models of this scenario, considering different line of sight positions of the stars (the position in the plane of the sky is known, thus fixed). Synthetic thermal X-ray emission maps are calculated from the numerical models and compared with ROSAT observations of this astrophysical object. Our models reproduce successfully both the observed X-ray morphology and the total X-ray luminosity, without taking into account thermal conduction effects.Comment: 8 pages, 6 figures, accepted for publication in MNRA

    Differences between adjusted vs. non- adjusted loads in velocity-based training: consequences for strength training control and programming

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    Strength and conditioning specialists commonly deal with the quantification and selection the setting of protocols regarding resistance training intensities. Although the one repetition maximum (1RM) method has been widely used to prescribe exercise intensity, the velocity-based training (VBT) method may enable a more optimal tool for better monitoring and planning of resistance training (RT) programs. The aim of this study was to compare the effects of two RT programs only differing in the training load prescription strategy (adjusting or not daily via VBT) with loads from 50 to 80% 1RM on 1RM, countermovement (CMJ) and sprint. Twenty-four male students with previous experience in RT were randomly assigned to two groups: adjusted loads (AL) (nD13) and non-adjusted loads (NAL) (nD11) and carried out an 8-week (16 sessions) RT program. The performance assessment pre- and post-training program included estimated 1RM and full load-velocity profile in the squat exercise; countermovement jump (CMJ); and 20-m sprint (T20). Relative intensity (RI) and mean propulsive velocity attained during each training session (Vsession) was monitored. Subjects in the NAL group trained at a significantly faster Vsession than those in AL (p < 0.001) (0.88 - 0.91 vs. 0.67- 0.68 m/s, with a 15% RM gap between groups for the last sessions), and did not achieve the maximum programmed intensity (80% RM). Significant differences were detected in sessions 3- 4, showing differences between programmed and performed Vsession and lower RI and velocity loss (VL) for the NAL compared to the AL group (p < 0.05). Although both groups improved 1RM, CMJ and T20, NAL experienced greater and significant changes than AL (28.90 vs.12.70%, 16.10 vs. 7.90% and -1.99 vs. - 0.95%, respectively). Load adjustment based on movement velocity is a useful way to control for highly individualised responses to training and improve the implementation of RT programs

    RF plasma cleaning of optical surfaces: A study of cleaning rates on different carbon allotropes as a function of RF powers and distances

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    An extended study on an advanced method for the cleaning of carbon contaminations on large optical surfaces using a remote inductively coupled low pressure RF plasma source (GV10x downstream asher) is reported in this work. Technical as well as scientific features of this scaled up cleaning process are analyzed, such as the cleaning efficiency for different carbon allotropes (amorphous and diamond-like carbon) as a function of feedstock gas composition, RF power (ranging from 30 to 300W), and source-object distances (415 to 840 mm). The underlying physical phenomena for these functional dependences are discussed.Comment: 16 pages, 9 figure

    X-ray emission and dynamics from large diameter superbubbles: The case of N 70 superbubble

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    The morphology, dynamics and thermal X-ray emission of the superbubble N70 is studied by means of 3D hydrodynamical simulations, carried out with the {\sc{yguaz\'u-a}} code. We have considered different scenarios: the superbubble being the product of a single supernova remnant, of the stellar winds from an OB association, or the result of the joint action of stellar winds and a supernova event. Our results show that, in spite that all scenarios produce bubbles with the observed physical size, only those where the bubble is driven by stellar winds and a SN event are successful to explain the general morphology, dynamics and the X-ray luminosity of N70. Our models predict temperatures in excess of 108K10^8 \mathrm{K} at the interior of the superbubble, however the density is too low and the emission in thermal X-ray above 2keV2 \mathrm{keV} is too faint to be detected.Comment: 9 pages, 11 figures, ApJ accepte
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