1,852 research outputs found
The 12 prophets dataset
The "Ajeijadinho 3D" project is an initiative supported by the University of
S\~ao Paulo (Museum of Science and Dean of Culture and Extension), which
involves the 3D digitization of art works of Brazilian sculptor Antonio
Francisco Lisboa, better known as Aleijadinho. The project made use of advanced
acquisition and processing of 3D meshes for preservation and dissemination of
the cultural heritage. The dissemination occurs through a Web portal, so that
the population has the opportunity to meet the art works in detail using 3D
visualization and interaction. The portal address is
http://www.aleijadinho3d.icmc.usp.br. The 3D acquisitions were conducted over a
week at the end of July 2013 in the cities of Ouro Preto, MG, Brazil and
Congonhas do Campo, MG, Brazil. The scanning was done with a special equipment
supplied by company Leica Geosystems, which allowed the work to take place at
distances between 10 and 30 meters, defining a non-invasive procedure,
simplified logistics, and without the need for preparation or isolation of the
sites. In Ouro Preto, we digitized the churches of Francisco of Assis, Our Lady
of Carmo, and Our Lady of Mercy; in Congonhas do Campo we scanned the entire
Sanctuary of Bom Jesus de Matosinhos and his 12 prophets. Once scanned, the art
works went through a long process of preparation, which required careful
handling of meshes done by experts from the University of S\~ao Paulo in
partnership with company Imprimate.Comment: Full dataset online at http://aleijadinho3d.icmc.usp.br/data.htm
Insight into determinants of substrate binding and transport in a multidrug efflux protein
Multidrug resistance arising from the activity of integral membrane transporter proteins presents a global public health threat. In bacteria such as Escherichia coli, transporter proteins belonging to the major facilitator superfamily make a considerable contribution to multidrug resistance by catalysing efflux of myriad structurally and chemically different antimicrobial compounds. Despite their clinical relevance, questions pertaining to mechanistic details of how these promiscuous proteins function remain outstanding, and the role(s) played by individual amino acid residues in recognition, binding and subsequent transport of different antimicrobial substrates by multidrug efflux members of the major facilitator superfamily requires illumination. Using in silico homology modelling, molecular docking and mutagenesis studies in combination with substrate binding and transport assays, we identified several amino acid residues that play important roles in antimicrobial substrate recognition, binding and transport by Escherichia coli MdtM, a representative multidrug efflux protein of the major facilitator superfamily. Furthermore, our studies suggested that ‘aromatic clamps’ formed by tyrosine and phenylalanine residues located within the substrate binding pocket of MdtM may be important for antimicrobial substrate recognition and transport by the protein. Such ‘clamps’ may be a structurally and functionally important feature of all major facilitator multidrug efflux proteins
Hybrid confinement of optical and mechanical modes in a bullseye optomechanical resonator
Optomechanical cavities have proven to be an exceptional tool to explore
fundamental and technological aspects of the interaction between mechanical and
optical waves. Such interactions strongly benefit from cavities with large
optomechanical coupling, high mechanical and optical quality factors, and
mechanical frequencies larger than the optical mode linewidth, the so called
resolved sideband limit. Here we demonstrate a novel optomechanical cavity
based on a disk with a radial mechanical bandgap. This design confines light
and mechanical waves through distinct physical mechanisms which allows for
independent control of the mechanical and optical properties. Our device design
is not limited by unique material properties and could be easily adapted to
allow large optomechanical coupling and high mechanical quality factors with
other promising materials. Finally, our demonstration is based on devices
fabricated on a commercial silicon photonics facility, demonstrating that our
approach can be easily scalable.Comment: 16 pages, 11 figure
Autosuficiencia energética en la vivienda
Resumen
Los edificios, junto al transporte suponen más de la mitad del consumo energético actual de combustible
y de la contaminación a este asociada, de difícil solución por la dispersión de los procesos de combustión
en poblaciones o carreteras. Esta distribución en la edificación de la demanda favorece el uso de energía
solar, el recurso renovable más abundante y de fácil acceso sobre la superficie terrestre, especialmente
adecuado en nuestro clima. El uso de tecnología solar requiere procesos de acumulación que garanticen
la disponibilidad del calor excesivo del verano durante las frías noches de invierno así como la iluminación
o las comunicaciones durante la noche en base a la radiación recibida en las horas de radiación solar. El
trabajo describe la posibilidad de captura térmica en la cubierta con almacenamiento selectivo en el subsuelo
capaz de satisfacer la demanda de energía para climatización de la vivienda a lo largo del año a un
coste ,muy bajo. La energía eléctrica de "alta calidad" se genera y acumulé1localmente en forma de hidrógeno
para alimentar según demanda mediante una pila de combustible. Con la tecnología actual, aún en
pleno desarrollo, el balance es claramente positivo lo que significa la posibilidad de autosuficiencia energética
para una parte considerable de las viviendas.El MEC ha financiado el desarrollo de
nuevos dispositivos de hidrógeno en el proyecto "Diseño y realización de una nueva Pila de
Combustible polimérica de bajo coste y alta eficacia" MCYT- ENE2005-09124-C04-02/ALT. y el
CSIC ha financiado la generación de hidrógeno a partir de residuos orgánicos. El P.S.E. INVISO
para industrialización de la vivienda sostenible financia el desarrollo integral de estos sistemas.Peer reviewe
Stimulated Brillouin scattering by surface acoustic waves in lithium niobate waveguides
We numerically demonstrate that Lithium Niobate on Insulator (LNOI)
waveguides may support confined short-wavelength surface acoustic waves that
interact strongly with optical fields through backward stimulated Brillouin
scattering in both and -cut orientation. We conduct fully anisotropic
simulations that consider not only moving boundary and photoelastic forces, but
also roto-optic forces for the Brillouin interaction. Our results indicate that
photoelasticity dominates the Brillouin gain and can reach as high as
= 0.43 Wm in standard ridge waveguide
A chip-scale integrated cavity-electro-optomechanics platform
We present an integrated optomechanical and electromechanical nanocavity, in
which a common mechanical degree of freedom is coupled to an ultrahigh-Q
photonic crystal defect cavity and an electrical circuit. The sys- tem allows
for wide-range, fast electrical tuning of the optical nanocavity resonances,
and for electrical control of optical radiation pressure back-action effects
such as mechanical amplification (phonon lasing), cooling, and stiffening.
These sort of integrated devices offer a new means to efficiently interconvert
weak microwave and optical signals, and are expected to pave the way for a new
class of micro-sensors utilizing optomechanical back-action for thermal noise
reduction and low-noise optical read-out.Comment: 11 pages, 7 figure
Ultrahigh-Q optomechanical crystal cavities fabricated in a CMOS foundry
FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESPhotonic crystals use periodic structures to create frequency regions where the optical wave propagation is forbidden, which allows the creation and integration of complex optical functionalities in small footprint devices. Such strategy has also been successfully applied to confine mechanical waves and to explore their interaction with light in the so-called optomechanical cavities. Because of their challenging design, these cavities are traditionally fabricated using dedicated high-resolution electron-beam lithography tools that are inherently slow, limiting this solution to small-scale or research applications. Here we show how to overcome this problem by using a deep-UV photolithography process to fabricate optomechanical crystals in a commercial CMOS foundry. We show that a careful design of the photonic crystals can withstand the limitations of the photolithography process, producing cavities with measured intrinsic optical quality factors as high as Q(i) = (1.21 +/- 0.02) x 10(6). Optomechanical crystals are also created using phononic crystals to tightly confine the GHz sound waves within the optical cavity, resulting in a measured vacuum optomechanical coupling rate of g(0) = 2 pi x (91 +/- 4) kHz. Efficient sideband cooling and amplification are also demonstrated since these cavities are in the resolved sideband regime. Further improvements in the design and fabrication process suggest that commercial foundry-based optomechanical cavities could be used for quantum ground-state cooling.716FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES2012/17610-32012/17765-72013/06360-92014/12875-42016/18308-0550504/2012-5153044/2013-6Sem informaçãoR.B., G.S.W. and T.P.M.A. designed the devices. R.B. performed the measurements with support from F.G.S.S., G.O.L. and supervision by T.P.M.A., R.B., G.S.W. and T.P.M.A. analyzed the measured data. All authors contributed to the writing of the manuscript
Synthesis and luminescence properties of electrodeposited ZnO Films
ZnO films have been grown on gold (111) by electrodeposition using two
different OH- sources, nitrate and peroxide, in order to obtain a comparative
study between these films. The morphology, structural and optical
characterization of the films were investigated depending on the solution used
(nitrate and peroxide) and the applied potential. Scanning Electron Microscopy
pictures show different morphologies in each case. X-Ray Diffraction confirms
that the films are pure ZnO oriented along the (0002) direction. ZnO films have
been studied by photoluminescence to identify the emission of defects in the
visible range. A consistent model that explains the emissions for the different
electrodeposited ZnO films is proposed. We have associated the green and yellow
emissions to a transition from the donor OH- to the acceptor zinc vacancies
(VZn-) and to interstitial oxygen (Oi0), respectively. The orange-red emission
is probably due to transitions from the conducting band to Oi- and OZn 0
defects and the infrared emission to transition from these Oi -/2- and OZn 0/-
defects to the valence band.Comment: 17 pages, 1 Table and 10 figure
Efficient anchor loss suppression in coupled near-field optomechanical resonators
FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQElastic dissipation through radiation towards the substrate is a major loss channel in micro-and nanomechanical resonators. Engineering the coupling of these resonators with optical cavities further complicates and constrains the design of low-loss optomechanical devices. In this work we rely on the coherent cancellation of mechanical radiation to demonstrate material and surface absorption limited silicon near-field optomechanical resonators oscillating at tens of MHz. The effectiveness of our dissipation suppression scheme is investigated at room and cryogenic temperatures. While at room temperature we can reach a maximum quality factor of 7.61k (fQ-product of the order of 10(11) Hz), at 22 K the quality factor increases to 37k, resulting in a fQ-product of 2 x 10(12) Hz.25253134731361FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ2008/57857-22012/17610-32012/17765-7153044/2013-
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