2,959 research outputs found
Agenda prospectiva de investigación de la cadena productiva de cacao-chocolate en Colombia
En este artÃculo se presentan los resultados del estudio cuyo objetivo fue la definición de la agenda prospectiva de investigación de la cadena para lo cual se implementó una metodologÃa que artÃculo herramientas como el análisis de desempeño, el benchmarking. La vigilancia tecnológica y comercial y la prospectiva, lográndose identificar tres áreas estratégicas para la investigación y desarrollo tecnológico de la cadena que agrupan 14 demandas tecnológicas las cuales se proponen abordar a través de 33 proyectos prioritarios para el mejoramiento de la posición competitiva de la cadena productiva del Cacao-Chocolate.Cacao-Theobroma caca
Phase preserving amplification near the quantum limit with a Josephson Ring Modulator
Recent progress in solid state quantum information processing has stimulated
the search for ultra-low-noise amplifiers and frequency converters in the
microwave frequency range, which could attain the ultimate limit imposed by
quantum mechanics. In this article, we report the first realization of an
intrinsically phase-preserving, non-degenerate superconducting parametric
amplifier, a so far missing component. It is based on the Josephson ring
modulator, which consists of four junctions in a Wheatstone bridge
configuration. The device symmetry greatly enhances the purity of the
amplification process and simplifies both its operation and analysis. The
measured characteristics of the amplifier in terms of gain and bandwidth are in
good agreement with analytical predictions. Using a newly developed noise
source, we also show that our device operates within a factor of three of the
quantum limit. This development opens new applications in the area of quantum
analog signal processing
Magnetic properties of submicron Co islands and their use as artificial pinning centers
We report on the magnetic properties of elongated submicron magnetic islands
and their influence on a superconducting film. The magnetic properties were
studied by magnetization hysteresis loop measurements and scanning-force
microscopy. In the as-grown state, the islands have a magnetic structure
consisting of two antiparallel domains. This stable domain configuration has
been directly visualized as a 2x2-checkerboard pattern by magnetic-force
microscopy. In the remanent state, after magnetic saturation along the easy
axis, all islands have a single-domain structure with the magnetic moment
oriented along the magnetizing field direction. Periodic lattices of these Co
islands act as efficient artificial pinning arrays for the flux lines in a
superconducting Pb film deposited on top of the Co islands. The influence of
the magnetic state of the dots on their pinning efficiency is investigated in
these films, before and after the Co dots are magnetized.Comment: 6 pages including figure
Characterization of radial turbulent fluxes in the Santander linear plasma machine
It is shown that the statistical and correlation properties of the local turbulent flux measured at different radial locations of the cold, weakly ionized plasmas inside the Santander Linear Plasma Machine [Castellanos et al., Plasma Phys. Control. Fusion 47, 2067 (2005)] are consistent with diffusive-like transport dynamics. This is in contrast to the dynamical behavior inferred from similar measurements taken in hotter, fully ionized tokamak and stellarator edge plasmas, in which longterm correlations and other features characteristic of complex, non-diffusive transport dynamics have been reported in the past. These results may shed some light on a recent controversy regarding the possible universality of the dynamics of turbulent transport in magnetized plasma
Rectangular core-collapse supernova remnants: application to Puppis A
Core-collapse supernova remnants are the gaseous nebulae of galactic
interstellar media (ISM) formed after the explosive death of massive stars.
Their morphology and emission properties depend both on the surrounding
circumstellar structure shaped by the stellar wind-ISM interaction of the
progenitor star and on the local conditions of the ambient medium. In the warm
phase of the Galactic plane (n = 1/cm3, T = 8000 K), an organised magnetic
field of strength 7 microG has profound consequences on the morphology of the
wind bubble of massive stars at rest. In this paper we show through 2.5D
magneto-hydrodynamical simulations, in the context of a Wolf-Rayet-evolving 35
Mo star, that it affects the development of its supernova remnant. When the
supernova remnant reaches its middle age (15 to 20 kyr), it adopts a tubular
shape that results from the interaction between the isotropic supernova ejecta
and the anisotropic, magnetised, shocked stellar progenitor bubble into which
the supernova blast wave expands. Our calculations for non-thermal emission,
i.e. radio synchrotron and inverse Compton radiation, reveal that such
supernova remnants can, due to projection effects, appear as rectangular
objects in certain cases. This mechanism for shaping a supernova remnant is
similar to the bipolar and elliptical planetary nebula production by wind-wind
interaction in the low-mass regime of stellar evolution. If such a rectangular
core-collapse supernova remnant is created, the progenitor star must not have
been a runaway star. We propose that such a mechanism is at work in the shaping
of the asymmetric core-collapse supernova remnant Puppis A.Comment: Accepted at MNRA
Phase Locking, Devil's Staircases, Farey Trees, and Arnold Tongues in Driven Vortex Lattices with Periodic Pinning
Using numerical simulations, we observe phase locking, Arnold tongues, and
Devil's staircases for vortex lattices driven at varying angles with respect to
an underlying superconducting periodic pinning array. This rich structure
should be observalble in transport measurments. The transverse curves
have a Devil's staircase structure, with plateaus occurring near the driving
angles along symmetry directions of the pinning array. Each of the plateaus
corresponds to a different dyanmical phase with a distinctive vortex structure
and flow pattern.Comment: accepted to Physical Review Letter
Chicamocha Canyon Geopark project: A novel strategy for the socio-economic development of Santander (Colombia) through geoeducation, geotourism and geoconservation
The proposed Chicamocha Canyon Geopark project is starting its way for nomination as a UNESCO Global Geopark under the recognition of the Global Geoparks Network. This paper aims to present the justifications of establishing this geopark. It also assesses the potential role of a geopark figure in Santander as an urgent measure to promote the geoconservation of the Chicamocha Canyon territory. The success of this project will not only improve the living conditions of local communities, but also will be a reference model in terms of geological conservation at national and international level. The Chicamocha Canyon, where is proposed to develop this project, has a great potential for the development of the tourism industry due to climatic conditions of the region, besides possessing a rich cultural and natural heritage that needs to be enhanced and protected. Undoubtedly, this initiative should satisfy all the requirements to be a UNESCO Global Geopark, which include a delimited area that defines a territory, the occurrence of geological features of international importance with scientific, educational and aesthetic value, the presence of other types of heritage such as archaeological sites, as well as a proper access infrastructure that favors the socio-economic development of the region. In order to guarantee the successful consolidation of the proposed geopark within the defined territory, this initiative must count the strong support of the local communities and must involve stakeholders such as government authorities, academic and research institutions, and local businesses
Microwave amplification with nanomechanical resonators
Sensitive measurement of electrical signals is at the heart of modern science
and technology. According to quantum mechanics, any detector or amplifier is
required to add a certain amount of noise to the signal, equaling at best the
energy of quantum fluctuations. The quantum limit of added noise has nearly
been reached with superconducting devices which take advantage of
nonlinearities in Josephson junctions. Here, we introduce a new paradigm of
amplification of microwave signals with the help of a mechanical oscillator. By
relying on the radiation pressure force on a nanomechanical resonator, we
provide an experimental demonstration and an analytical description of how the
injection of microwaves induces coherent stimulated emission and signal
amplification. This scheme, based on two linear oscillators, has the advantage
of being conceptually and practically simpler than the Josephson junction
devices, and, at the same time, has a high potential to reach quantum limited
operation. With a measured signal amplification of 25 decibels and the addition
of 20 quanta of noise, we anticipate near quantum-limited mechanical microwave
amplification is feasible in various applications involving integrated
electrical circuits.Comment: Main text + supplementary information. 14 pages, 3 figures (main
text), 18 pages, 6 figures (supplementary information
CD69 is a TGF-β/1α,25-dihydroxyvitamin D3 target gene in monocytes
CD69 is a transmembrane lectin that can be expressed on most hematopoietic cells. In monocytes, it has been functionally linked to the 5-lipoxygenase pathway in which the leukotrienes, a class of highly potent inflammatory mediators, are produced. However, regarding CD69 gene expression and its regulatory mechanisms in monocytes, only scarce data are available. Here, we report that CD69 mRNA expression, analogous to that of 5-lipoxygenase, is induced by the physiologic stimuli transforming growth factor-β (TGF-β) and 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3) in monocytic cells. Comparison with T- and B-cell lines showed that the effect was specific for monocytes. CD69 expression levels were increased in a concentration-dependent manner, and kinetic analysis revealed a rapid onset of mRNA expression, indicating that CD69 is a primary TGF-β/1α,25(OH)2D3 target gene. PCR analysis of different regions of the CD69 mRNA revealed that de novo transcription was initiated and proximal and distal parts were induced concomitantly. In common with 5-lipoxygenase, no activation of 0.7 kb or ~2.3 kb promoter fragments by TGF-β and 1α,25(OH)2D3 could be observed in transient reporter assays for CD69. Analysis of mRNA stability using a transcription inhibitor and a 3′UTR reporter construct showed that TGF-β and 1α,25(OH)2D3 do not influence CD69 mRNA stability. Functional knockdown of Smad3 clearly demonstrated that upregulation of CD69 mRNA, in contrast to 5-LO, depends on Smad3. Comparative studies with different inhibitors for mitogen activated protein kinases (MAPKs) revealed that MAPK signalling is involved in CD69 gene regulation, whereas 5-lipoxygenase gene expression was only partly affected. Mechanistically, we found evidence that CD69 gene upregulation depends on TAK1-mediated p38 activation. In summary, our data indicate that CD69 gene expression, conforming with 5-lipoxygenase, is regulated monocyte-specifically by the physiologic stimuli TGF-β and 1α,25(OH)2D3 on mRNA level, although different mechanisms account for the upregulation of each gene
Dissolving microarray patches for transdermal delivery of risperidone for schizophrenia management
Schizophrenia is a psychiatric disorder that results from abnormal levels of neurotransmitters in the brain. Risperidone (RIS) is a common drug prescribed for the treatment of schizophrenia. RIS is a hydrophobic drug that is typically administered orally or intramuscularly. Transdermal drug delivery (TDD) could potentially improve the delivery of RIS. This study focused on the development of RIS nanocrystals (NCs), for the first time, which were incorporated into dissolving microneedle array patches (DMAPs) to facilitate the drug delivery of RIS. RIS NCs were formulated via wet-media milling technique using poly(vinylalcohol) (PVA) as a stabiliser. NCs with particle size of 300 nm were produced and showed an enhanced release profile up to 80 % over 28 days. Ex vivo results showed that 1.16 ± 0.04 mg of RIS was delivered to both the receiver compartment and full-thickness skin from NCs loaded DMAPs compared to 0.75 ± 0.07 mg from bulk RIS DMAPs. In an in vivo study conducted using female Sprague Dawley rats, both RIS and its active metabolite 9-hydroxyrisperidone (9-OH-RIS) were detected in plasma samples for 5 days. In comparison with the oral group, DMAPs improved the overall pharmacokinetic profile in plasma with a ∼ 15 folds higher area under the curve (AUC) value. This work has represented the novel delivery of the antipsychotic drug, RIS, through microneedles. It also offers substantial evidence to support the broader application of MAPs for the transdermal delivery of poorly water-soluble drugs
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