1,106 research outputs found
Quantum autoencoders via quantum adders with genetic algorithms
The quantum autoencoder is a recent paradigm in the field of quantum machine
learning, which may enable an enhanced use of resources in quantum
technologies. To this end, quantum neural networks with less nodes in the inner
than in the outer layers were considered. Here, we propose a useful connection
between approximate quantum adders and quantum autoencoders. Specifically, this
link allows us to employ optimized approximate quantum adders, obtained with
genetic algorithms, for the implementation of quantum autoencoders for a
variety of initial states. Furthermore, we can also directly optimize the
quantum autoencoders via genetic algorithms. Our approach opens a different
path for the design of quantum autoencoders in controllable quantum platforms
High volume-per-dose and low resistivity of cobalt nanowires grown by Ga+ focused ion beam induced deposition
The growth of ferromagnetic nanostructures by means of focused-Ga+-beam-induced deposition (Ga+-FIBID) using the Co2(CO)8 precursor has been systematically investigated. The work aimed to obtain growth conditions allowing for the simultaneous occurrence of high growth speed, good lateral resolution, low electrical resistivity, and ferromagnetic behavior. As a first result, it has been found that the competition between deposition and milling that is produced by the Ga+ beam is a limiting factor. In our working conditions, with the maximum available precursor flux, the maximum deposit thickness has been found to be 65 nm. The obtained volumetric growth rate is at least 50 times higher than in the case of deposition by focused-electron-beam-induced deposition. The lateral resolution of the deposits can be as good as 50 nm while using Ga+-beam currents lower than 10 pA. The high metallic content of the as-grown deposits gives rise to a low electrical resistivity, within the range 20-40 µ¿cm. Magnetic measurements confirm the ferromagnetic nature of the deposits at room temperature. In conclusion, the set of obtained results indicates that the growth of functional ferromagnetic nanostructures by Ga+-FIBID while using the Co2(CO)8 precursor is a viable and competitive technique when compared to related nanofabrication techniques
Effects of Topography and Surface Soil Cover on Erosion for Mining Reclamation: The Experimental Spoil Heap at El Machorro Mine (Central Spain)
Mining reclamation tries to reduce environmental impacts, including accelerated runoff, erosion and sediment load in the nearby fluvial networks and their ecosystems. This study compares the effects of topography and surface soil cover on erosion on man-made slopes coming from surface mining reclamation in Central Spain. Two topographic profiles, linear and concave, with two surface soil covers, subsoil and topsoil, were monitored for two hydrologic years. Sediment load, rill development and plant colonization from the four profiles were measured under field conditions. The results show that, in the case of this experiment, a thick and non-compacted topsoil cover on a linear slope yielded less sediment than carbonate colluvium or topsoil cover on a concave slope. This study also shows that vegetation establishment, which plays an important role in erosion control, depends on topography. Plant cover was more widespread and more homogeneous on linear profiles with topsoil cover. On concave slopes, plant establishment was severely limited on the steepest upper part and favoured in the bottom. This study suggests that management of topography and surface soil cover should be approached systematically, taking three outcomes into consideration: (i) topsoil can lead to a successful mining reclamation regardless of topography, (ii) created concave slopes can lead to a successful mining reclamation and (iii) topography determines the vegetation colonization pattern.The experiment was funded by a research contract between the Spanish mining company
602 CAOBAR S.A. and the Department of Geodynamics of the Complutense University of Madrid
603 (research contract numbers 234/2007, 290/2008 261/2009). The data analyses and manuscript
604 production were developed within two Research Projects, CGL2009-14508-C02-01 and
605 CGL2010-21754-C02, of the Spanish Ministry of Science and Technology and by the
606 Ecological Restoration network REMEDINAL-2 (S2009/AMB-1783).Peer reviewe
The exponential ordering for nonautonomous delay systems with applications to compartmental Nicholson systems
Producción CientíficaThe exponential ordering is exploited in the context of nonautonomous delay
systems, inducing monotone skew-product semiflows under less restrictive conditions
than usual. Some dynamical concepts linked to the order, such as semiequilibria, are
considered for the exponential ordering, with implications for the determination of
the presence of uniform persistence or the existence of global attractors. Also, some
important conclusions on the long-term dynamics and attraction are obtained for
monotone and sublinear delay systems for this ordering. The results are then applied
to almost periodic Nicholson systems and new conditions are given for the existence
of a unique almost periodic positive solution which asymptotically attracts every
other positive solution.The first three authors were partly supported by MICIIN/FEDER project RTI2018- 096523-B-I00 and by Universidad de Valladolid under project PIP-TCESC-2020. The fourth author was partly supported by MICINN/FEDER under projects RTI2018-096523-B-I00 and PGC2018-097565-B-I0
On the usage of GRECOSAR, an orbital polarimetric SAR simulator of complex targets, to vessel classification studies
This paper presents a synthetic aperture radar (SAR)
simulator that is able to generate polarimetric SAR (POLSAR)
and polarimetric inverse SAR data of complex targets. It solves
the electromagnetic problem via high-frequency approximations,
such as physical optics and the physical theory of diffraction,
with notable computational efficiency. In principle, any orbital
monostatic sensor working at any band, resolution, and operating
mode can be modeled. To make simulations more realistic, the
target’s bearing and speed are considered, and for the particular
case of vessels, even the translational and rotational movements
induced by the sea state. All these capabilities make the simulator
a powerful tool for supplying large amounts of data with precise
scenario information and for testing future sensor configurations.
In this paper, the usefulness of the simulator on vessel classification
studies is assessed. Several simulated polarimetric images are
presented to analyze the potentialities of coherent target decompositions
for classifying complex geometries, thus basing an operational
algorithm. The limitations highlighted by the results suggest
that other approaches, like POLSAR interferometry, should be
explored.Peer Reviewe
Cylindrical Three-Dimensional Porous Anodic Alumina Networks
The synthesis of a conformal three-dimensional nanostructure based on porous anodic alumina with transversal nanopores on wires is herein presented. The resulting three-dimensional network exhibits the same nanostructure as that obtained on planar geometries, but with a macroscopic cylindrical geometry. The morphological analysis of the nanostructure revealed the effects of the initial defects on the aluminum surface and the mechanical strains on the integrity of the three-dimensional network. The results evidence the feasibility of obtaining 3D porous anodic alumina on non-planar aluminum substrates.The European Research Council and the EU-H2020 program are gratefully acknowledged for co-funding this
work through the projects Tonality (ERC-2014-PoC) and Marie Skłodowska-Curie Fellow (706094–TONSOPS).
We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)
A Fungal Effector With Host Nuclear Localization and DNA-Binding Properties Is Required for Maize Anthracnose Development
Plant pathogens have the capacity to manipulate the host immune system through the secretion of effectors. We identified 27 putative effector proteins encoded in the genome of the maize anthracnose pathogen Colletotrichum graminicola that are likely to target the host’s nucleus, as they simultaneously contain sequence signatures for secretion and nuclear localization. We functionally characterized one protein, identified as CgEP1. This protein is synthesized during the early stages of disease development and is necessary for anthracnose development in maize leaves, stems, and roots. Genetic, molecular, and biochemical studies confirmed that this effector targets the host’s nucleus and defines a novel class of double-stranded DNA-binding protein. We show that CgEP1 arose from a gene duplication in an ancestor of a lineage of monocot-infecting Colletotrichum spp. and has undergone an intense evolution process, with evidence for episodes of positive selection. We detected CgEP1 homologs in several species of a grass-infecting lineage of Colletotrichum spp., suggesting that its function may be conserved across a large number of anthracnose pathogens. Our results demonstrate that effectors targeted to the host nucleus may be key elements for disease development and aid in the understanding of the genetic basis of anthracnose development in maize plants.Fil: Vargas, Walter Alberto. Universidad de Salamanca; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sanz Martín, José M.. Universidad de Salamanca; EspañaFil: Rech, Gabriel E.. Universidad de Salamanca; EspañaFil: Armijos Jaramillo, Vinicio D.. Universidad de Salamanca; EspañaFil: Rivera Rodriguez, Lina Patricia. Universidad de Salamanca; EspañaFil: Echeverria, María de Las Mercedes. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Díaz Mínguez, José M.. Universidad de Salamanca; EspañaFil: Thon, Michael R.. Universidad de Salamanca; EspañaFil: Sukno, Serenella A.. Universidad de Salamanca; Españ
Strongly hyperbolic Hamiltonian systems in numerical relativity: Formulation and symplectic integration
We consider two strongly hyperbolic Hamiltonian formulations of general
relativity and their numerical integration with a free and a partially
constrained symplectic integrator. In those formulations we use hyperbolic
drivers for the shift and in one case also for the densitized lapse. A system
where the densitized lapse is an external field allows to enforce the momentum
constraints in a holonomically constrained Hamiltonian system and to turn the
Hamilton constraint function from a weak to a strong invariant.
These schemes are tested in a perturbed Minkowski and the Schwarzschild
space-time. In those examples we find advantages of the strongly hyperbolic
formulations over the ADM system presented in [arXiv:0807.0734]. Furthermore we
observe stabilizing effects of the partially constrained evolution in
Schwarzschild space-time as long as the momentum constraints are enforced.Comment: This version clarifies some points concerning the interpretation of
the result
Validation of high-pressure homogenization process to pasteurize Brazil nut (Bertholletia excelsa) beverages: Sensorial and quality characteristics during cold storage
The effect of high-pressure homogenization (HPH) on the inactivation of Escherichia coli and the stability of the quality properties of Brazil nut beverages were studied. E. coli was used as target microorganism to validate the HPH process (pressures from 50 to 180 MPa and inlet temperatures (Ti) from 25 to 75 °C). Cold storage (5 °C) for 21 days was conducted to establish the shelf-life of BN beverages, in terms of their microbiological, physical, physicochemical, and sensorial stability. HPH-treated samples were compared to pasteurized BN beverages (63 °C for 20 min). The combination of Ti and the pressure of the HPH process (50 to 150 MPa/75 °C and 180 MPa/25 °C) had a significant effect on E. coli inactivation (8.2 log CFU/mL). During storage at 5 °C, the growth of mesophilic aerobes in processed BN beverages was controlled by the HPH process. Oxidative stability (TBAR assay) and physicochemical properties (pH, acidity, and °Brix) were evaluated during cold storage, showing good stability. Additionally, HPH-treated beverages showed a reduction in their particle size and the formation of more stable protein aggregates, which favored the beverages’ whiteness (color). The HPH process could be an alternative to pasteurization to obtain Brazil nut beverages with an acceptable microbiological shelf life (≥21 days at 5 °C) and high-quality characteristics without the use of any additivesThe authors gratefully acknowledge the financial support from PID2020-118300RB-C21 project from the Spanish Ministry of Science and Innovation and Comunidad Autónoma de Madrid (ALIBIRD, project: P2013/ABI2728) and Wilson V. Vasquez thanks the scholarship “Presidente de la Republica” postgrad program (RJ 4285-2018/MINEDU/VMGI-PRONABEC-OBE) from the Ministry of Education of the Republic of Per
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