1,421 research outputs found
Digital compensation of the side-band-rejection ratio in a fully analog 2SB sub-millimeter receiver
In observational radio astronomy, sideband-separating receivers are
preferred, particularly under high atmospheric noise, which is usually the case
in the sub-millimeter range. However, obtaining a good rejection ratio between
the two sidebands is difficult since, unavoidably, imbalances in the different
analog components appear. We describe a method to correct these imbalances
without making any change in the analog part of the sideband-separating
receiver, specifically, keeping the intermediate-frequency hybrid in place.
This opens the possibility of implementing the method in any existing receiver.
We have built hardware to demonstrate the validity of the method and tested it
on a fully analog receiver operating between 600 and 720GHz. We have tested the
stability of calibration and performance vs time and after full resets of the
receiver. We have performed an error analysis to compare the digital
compensation in two configurations of analog receivers, with and without
intermediate frequency (IF) hybrid. An average compensated sideband rejection
ratio of 46dB is obtained. Degradation of the compensated sideband rejection
ratio on time and after several resets of the receiver is minimal. A receiver
with an IF hybrid is more robust to systematic errors. Moreover, we have shown
that the intrinsic random errors in calibration have the same impact for
configuration without IF hybrid and for a configuration with IF hybrid with
analog rejection ratio better than 10dB. Compensated rejection ratios above
40dB are obtained even in the presence of high analog rejection. The method is
robust allowing its use under normal operational conditions at any telescope.
We also demonstrate that a full analog receiver is more robust against
systematic errors. Finally, the error bars associated to the compensated
rejection ratio are almost independent of whether IF hybrid is present or not
Effect of supplementary physical training on vertical jump height in professional ballet dancers
Covariate effects of resting heart rate variability on affective ratings and startle reflex during cognitive reappraisal of negative emotions
Heart Rate Variability (HRV) has been widely studied in laboratory settings due to its clinical implications, primarily as a potential biomarker of emotion regulation (ER). Studies have reported that individuals with higher resting HRV show more distinct startle reflexes to negative stimuli as compared to those with lower HRV. These responses have been associated with better defense system function when managing the context demands. There is, however, a lack of empirical evidence on the association between resting HRV and eyeblinks during laboratory tasks using instructed ER. This study explored the influence of tonic HRV on voluntary cognitive reappraisal through subjective and startle responses measured during an independent ER task. In total, 122 healthy participants completed a task consisting of attempts to upregulate, downregulate, or react naturally to emotions prompted by unpleasant pictures. Tonic HRV was measured for 5 minutes before the experiment began. Current results did not support the idea that self-reported and eyeblink responses were influenced by resting HRV. These findings suggest that, irrespective of resting HRV, individuals may benefit from strategies such as reappraisal that are useful for managing negative emotions. Experimental studies should further explore the role of individual differences when using ER strategies during laboratory task
Micromechanical Behavior of CuAlBe Shape Memory Alloy Undergoing 3-Point Bending Analyzed by Digital Image Correlation
A Parametric Study of Wave Interaction With a Rotor Having Hydrofoil Blades
Our recent progress on studying wave interaction with a lift-type rotor is discussed in this paper. The particular focus is on characterization of the rotor’s unidirectional responsiveness in waves. The rotor consists of six hydrofoil blades in two sets. One blade set has three blades laid out as a vertical-axis wind turbine of the Darrieus type. The other blade set has three blades configured like a Wells turbine. In combination, the formed rotor can be driven by flows in any direction to perform unidirectional rotation about its vertically mounted shaft. This unidirectional responsiveness of the rotor also holds in waves, making the rotor a valuable device for wave energy conversion. For parametric study of the rotor, hydrofoil blades using different cross sectional profiles and chord lengths have been employed to configure the rotor. The rotor was then tested in a wave flume under various wave conditions in a freewheeling mode. Experimental results were analyzed and discussed. The yielded research findings will greatly enhance the fundamental understanding on the rotor performance in waves, and effectively guide the prototype rotor development for practical applications
Monoclonal antibody-based immunoassays for cyprodinil residue analysis in QuEChERS-based fruit extracts
Cyprodinil is among the most common agrochemical residues found in highly perishable fruits, such as strawberries. In the present study, high-affinity monoclonal antibodies to this anilinopyrimidine fungicide were raised for the first time with the aim to produce valuable immunochemical analytical assays. Cyprodinil bioconjugates and the generated novel monoclonal antibodies were employed for sensitive competitive immunoassay development in two different formats. The limits of detection of the optimized assays were 20 and 30 ng L-1 for the indirect and direct assay, respectively. Influence over assay parameters of different physicochemical factors was studied. Strawberry samples were extracted following the recommended QuEChERS procedure for pesticide residues in food, and analyzed by the optimized immunoassays. Recoveries and coefficients of variation from fortified samples were within standard values. In addition, the obtained immunochemical results with naturally contaminated samples were statistically comparable, according to Deming regression analysis, to those of a reference chromatographic method.This work was supported by the Spanish Ministerio de Ciencia e Innovación (AGL2009-12940-C02-01-02/ALI and AGL2012-39965-C02-01-02/ALI) and cofinanced by FEDER Funds. J.V.M. and F.A.E.-T. were hired by the Consejo Superior de Investigaciones Científicas (CSIC), the former under a Ramón y Cajal contract and the latter under a JAE-doc contract, both of them financed by Ministerio de Ciencia e Innovación and the European Social Fund – European Union. G.Q.-R. is a recipient of a PROMEP predoctoral fellowship from Secretaría de Educación Pública of the Mexican government. Proteomic analysis was carried out in the SCIE University of Valencia Proteomics Unit, a member of the ISCIII ProteoRedProteomics Platform.Peer Reviewe
Evaluación de la actividad de los catalizadores 5% pd/tio2 y 5% pd/tio2 – 5%na en la reacción de hidrodecloración de cloroformo
Se evaluó la actividad de los catalizadores 5%Pd/TiO2 y por primera vez 5%Pd/TiO2-5%Na en la reacción de hidrodecloración de cloroformo en fase líquida a temperatura ambiente y 50°C, utilizando isopropanol c omo solvente y donor de hidrógeno. Se encontró que el catalizador 5%Pd/TiO2-5%Na presentó la mejor actividad tanto a temperatura ambiente como a 50°C, obteniénd ose la mayor conversión a 50°C (32,5%) luego de 5 horas de reacción. La incorporación de los iones sodio en el soporte, favoreció tanto la deshidrogenación del isopropanol, como la captura de los iones cloruro producidos durante la reacción, y por ende la hidrodecloración del cloroformo. Los catalizadores se caracterizaron por AAS, titulación en masa, DRX, BET, quimisorción de hidrógeno, TPR y TGA. El Na y el Pd se depositaron en el soporte prácticamente sin pérdidas; no se observó modificación de la fase cristalina anatasa del TiO2. La modificación del soporte con NaOH, aumentó su punto isoeléctrico, lo que correlaciona con un incremento en su basicidad y parece ser responsable de la mejora en actividad catalítica ABSTRACT The activity of 5%Pd/TiO2 and for the first time 5%Pd/TiO2-5%Na catalysts was evaluated in the liquid phase catalytic hydrodechlorination of chloroform at room temperature and 50°C, using isopropanol as solvent a nd hydrogen donor. 5%Pd/TiO2-5%Na catalyst showed the best catalytic performance at room temperature and 50°C, with the highest conversion at 50°C (32.5%) a fter 5 hours of reaction. The incorporation of sodium ions into the support favored both the dehydrogenation of isopropanol and the capture of chloride ions produced during the reaction, both positive for the hydrodechlorination of chloroform. The catalysts were characterized by AAS, mass titration, XRD, BET, hydrogen chemisorption, TPR and TGA. Na and Pd were loaded on the support practically without loss. and the anatase phase of titanium dioxide did not change with the addition of NaOH increased the catalyst’s isoelectric point, indicating an increase in catalyst basicity. This can explain the improved activity of Na-containing catalysts
Marine actinomycetes for biocontrol of Fusarium solani in tomato plants: In vitro and in vivo studies
Using microorganisms as biocontrol agents of phytopathogens has been an alternative to synthetic fungicides. Actinomycetes isolated from soil and plants have reduced diseases caused by phytopathogens; however, microorganisms from marine environments may be an option as biocontrol agents. The tomato crop possesses an important economic impact worldwide, being Mexico the main exporter. Several species of Fusarium cause damage to tomato crops and are controlled with synthetic fungicides. The objective of this work was to determine the effect of marine actinomycetes as biocontrol on Fusarium solani in tomato plants. Four strains of marine actinomycetes (A20, A19, A18, and A15) and one terrestrial actinomycete (ED48) were used. The actinomycetes strains used, produced siderophores. The greatest inhibition of mycelial growth of F. solani due to iron competition was obtained by strain A19 with 74.28%. Only two actinomycetes showed antifungal activity by VOCs (A19 and A18), strain A19 showed the highest antagonistic activity with PICR of 76.75%. Actinomycetes treatments showed significant differences with synthetic fungicide application in growth, disease severity (SE), and disease incidence (DI) variables. The application of marine actinomycete (A19) on plants infested with F. solani increased the levels of enzyme activity (SOD, POD, CAT, and PAL) versus plants in that only F. solani and distilled water (control) were applied. Actinomycetes of marine origin are an option as biocontrol agents for F. solani
Electron density contour maps via Rietveld-MEM analysis using HR-XRD for the polycrystalline ferroelectric BCZT
The maximum entropy method in combination with the Rietveld refinement method applied to the analysis (Rietveld-MEM analysis) of high-resolution x-ray diffraction (HR-XRD) is an important tool to elucidate the electron density distribution and chemical bonding nature of materials. In this work, we present the comparison of electron density distribution obtained from the Rietveld-MEM analysis for polycrystalline perovskite BaTiO3 (reference sample) and Ba0.9Ca0.2Ti0.9Zr0.1O3 (BCZT). To perform this task, HR-XRD patterns using synchrotron radiation were acquired. Tetragonal phase with P4mm (No.99) space group and pseudo-Voigt function were considered to model the HR-XRD peaks by the Rietveld method using the profile fitting Fullprof suite program. VESTA software was used to visualize 3D, 2D electron density distribution maps and line profiled to monitor the chemical bonding nature between Ba-O and Ti-O interactions and to visualize the off-center displacement of Ti cations by the incorporation of Zr and Ca cations. The interaction between Ti contours with O contours in the electron density distribution and the minimum electron density values revealed the enhancement of covalent nature and predominant ionic nature between barium and oxygen ions in the BCZT. To monitor the ferroelectric hysteresis behavior, polarization versus electric field curves complement the characterization of these samples
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