367 research outputs found
Multiport Multiband Decoupling Optimization for Miniature Antennas
Multiband multiport antennas are increasingly used for wireless communications and sensing miniature devices. The equations governing the multiport multiband antennas are analyzed in this paper with the objective of drawing the design guidelines for low coupling small antennas. Those guidelines have been applied in the design and optimization of a two-port dual band small antenna of size around λ0/13 x λ0/13 at the lowest frequency. Certain coupling conditions are applied to the port loads achieving a coupling reduction of 8 dB when having a simple two-element real load. A reduction of 27 dB can be obtained when having ideal loads composed by a higher number of elements. The antenna geometry is shown together with coupling minimization results
Ochratoxin A-induced cytotoxicity in liver (HepG2) cells: Impact of serum concentration, dietary antioxidants and glutathione-modulating compounds
Abbrevations: BSO, buthionine sulfoximine; CAT, catechin; DMSO, dimethyl sulfoxide; DTNB, dithio-bis-nitrobenzoic acid; EGCG, epigallocatechin gallate; FCS, foetal calf serum; GSH, glutathione; IARC, international agency for research on cancer; NAC, N-acetylcysteine; NO, nitric oxide; NR, neutral red; OATP, organic anion-transporting polypeptide; OTA, ochratoxin A; PBS, phosphate buffered saline; QUE, quercetin; ROS, reactive oxygen species; ROSAC, rosmarinic acid; RPMI, roswell park memorial institute; α-TOC, α-tocopherol; α-TOC-P, α-tocopherol phosphat
The Gaia-ESO Survey: dynamics of ionized and neutral gas in the Lagoon nebula (M8)
We present a spectroscopic study of the dynamics of the ionized and neutral
gas throughout the Lagoon nebula (M8), using VLT/FLAMES data from the Gaia-ESO
Survey. We explore the connections between the nebular gas and the stellar
population of the associated star cluster NGC6530. We characterize through
spectral fitting emission lines of H-alpha, [N II] and [S II] doublets, [O
III], and absorption lines of sodium D doublet, using data from the
FLAMES/Giraffe and UVES spectrographs, on more than 1000 sightlines towards the
entire face of the Lagoon nebula. Gas temperatures are derived from line-width
comparisons, densities from the [S II] doublet ratio, and ionization parameter
from H-alpha/[N II] ratio. Although doubly-peaked emission profiles are rarely
found, line asymmetries often imply multiple velocity components along the line
of sight. This is especially true for the sodium absorption, and for the [O
III] lines. Spatial maps for density and ionization are derived, and compared
to other known properties of the nebula and of its massive stars 9 Sgr,
Herschel 36 and HD 165052 which are confirmed to provide most of the ionizing
flux. The detailed velocity fields across the nebula show several expanding
shells, related to the cluster NGC6530, the O stars 9 Sgr and Herschel 36, and
the massive protostar M8East-IR. The origins of kinematical expansion and
ionization of the NGC6530 shell appear to be different. We are able to put
constrains on the line-of-sight (relative or absolute) distances between some
of these objects and the molecular cloud. The large obscuring band running
through the middle of the nebula is being compressed by both sides, which might
explain its enhanced density. We also find an unexplained large-scale velocity
gradient across the entire nebula. At larger distances, the transition from
ionized to neutral gas is studied using the sodium lines.Comment: 26 pages, 31 figures, accepted on Astronomy and Astrophysics journa
New transit observations for HAT-P-30 b, HAT-P-37 b, TrES-5 b, WASP-28 b, WASP-36 b, and WASP-39 b
We present new transit light curves for planets in six extrasolar planetary
systems. They were acquired with 0.4-2.2 m telescopes located in west Asia,
Europe, and South America. When combined with literature data, they allowed us
to redetermine system parameters in a homogeneous way. Our results for
individual systems are in agreement with values reported in previous studies.
We refined transit ephemerides and reduced uncertainties of orbital periods by
a factor between 2 and 7. No sign of any variations in transit times was
detected for the planets studied.Comment: Submitted to Acta Astronomic
Vehicular mm-Wave Array for Smart Handover
[EN] The emergence of new technologies such as autonomous
vehicles and high data rate 5G networks requires advanced
antenna types that are capable of fulfilling requirements for
highly demanding wireless communication links. The array of
microstrip-fed slot-coupled patches is one such type of antenna
that provides low return loss and good transient behaviour for
broadband applications. A compact size slot-coupled patch
antenna subarray and its phased array is proposed in this paper.
Two different substrates Rogers TMM4 and Green TapeTM 951
Low Temperature Co-Fired Ceramic (LTCC) are considered for
the fabrication of microstrip feedline. The feedline is fabricated
on the respective substrates and then mounted on a Rogers
RT/duroid 5880 laminate. Ground planes are used on both the
front and backside of the antenna array. The antenna is operating
in a range of 24.25 GHz - 29.5 GHz. A Smart Array is proposed
in this paper which has a good performance in terms of antenna
gain and scanning property for 5G application in Smart
handovers.This work was partly funded by the Ministerio de Ciencia e
Innovacion (MICINN) under projects TEC2016-78028-C3-1-
P, PID 2019-107885GB-C31, MDM2016-0600, and Catalan
Research Group 2017 SGR 219.Bharath Reddy, G.; Ramirez, GA.; Molins-Benlliure, J.; Ferrando Bataller, M.; Romeu, J.; Jofre-R., L. (2020). Vehicular mm-Wave Array for Smart Handover. Universidad de Málaga. 1-4. http://hdl.handle.net/10251/178564S1
The beta Pictoris association: Catalog of photometric rotational periods of low-mass members and candidate members
We intended to compile the most complete catalog of bona fide members and
candidate members of the beta Pictoris association, and to measure their
rotation periods and basic properties from our own observations, public
archives, and exploring the literature. We carried out a multi-observatories
campaign to get our own photometric time series and collected all archived
public photometric data time series for the stars in our catalog. Each time
series was analyzed with the Lomb-Scargle and CLEAN periodograms to search for
the stellar rotation periods. We complemented the measured rotational
properties with detailed information on multiplicity, membership, and projected
rotational velocity available in the literature and discussed star by star. We
measured the rotation periods of 112 out of 117 among bona fide members and
candidate members of the beta Pictoris association and, whenever possible, we
also measured the luminosity, radius, and inclination of the stellar rotation
axis. This represents to date the largest catalog of rotation periods of any
young loose stellar association. We provided an extensive catalog of rotation
periods together with other relevant basic properties useful to explore a
number of open issues, such as the causes of spread of rotation periods among
coeval stars, evolution of angular momentum, and lithium-rotation connection.Comment: Forthcoming article, Received: 20 June 2016 / Accepted: 09 September
2016; 40 pages, 2 figures. The online figures A1-A73 are available at CD
Smart Beam Management for Vehicular Networks Using ML
[EN] The mmWave frequencies will be widely used in future
vehicular communications. At these frequencies, the radio
channel becomes much more vulnerable to slight changes in the
environment like motions of the device, reflections or blockage. In
high mobility vehicular communications the rapidly changing
vehicle environments and the large overheads due to frequent
beam training are the critical disadvantages in developing these
systems at mmWave frequencies. Hence, smart beam
management procedures are desired to establish and maintain the
radio channels. In this paper, we propose that using the positions
and respective velocities of the vehicles in the dynamic selection
of the beam pair, and then adapting to the changing environments
using ML algorithms, can improve both network performance
and communication stability in high mobility vehicular
communications.This work was supported by the Spanish Comision
Interministerial de Ciencia y Tecnologia (CICYT) under
projects TEC2016-78028-C3-1-P and MDM2016-O6OO,
Catalan Research Group 2017 SGR 21, and Industrial
Doctorate programme (2018-DI-084) of Generalitat de
Catalunya.Bharath-Reddy, G.; Montero, L.; Perez-Romero, J.; Molins-Benlliure, J.; Ferrando Bataller, M.; Molina, J.; Romeu, J.... (2021). Smart Beam Management for Vehicular Networks Using ML. Íñigo Cuiñas Gómez. 1-4. http://hdl.handle.net/10251/1910661
The Gaia-ESO Survey: the selection function of the Milky Way field stars
The Gaia-ESO Survey was designed to target all major Galactic components
(i.e., bulge, thin and thick discs, halo and clusters), with the goal of
constraining the chemical and dynamical evolution of the Milky Way. This paper
presents the methodology and considerations that drive the selection of the
targeted, allocated and successfully observed Milky Way field stars. The
detailed understanding of the survey construction, specifically the influence
of target selection criteria on observed Milky Way field stars is required in
order to analyse and interpret the survey data correctly. We present the target
selection process for the Milky Way field stars observed with VLT/FLAMES and
provide the weights that characterise the survey target selection. The weights
can be used to account for the selection effects in the Gaia-ESO Survey data
for scientific studies. We provide a couple of simple examples to highlight the
necessity of including such information in studies of the stellar populations
in the Milky Way.Comment: 18 pages, 19 figures, Accepted for publication in MNRAS (April 25,
2016
Colliding Axion-Dilaton Plane Waves from Black Holes
The colliding plane wave metric discovered by Ferrari and Iba\~{n}ez to be
locally isometric to the interior of a Schwarzschild black hole is extended to
the case of general axion-dilaton black holes. Because the transformation maps
either black hole horizon to the focal plane of the colliding waves, this
entire class of colliding plane wave spacetimes only suffers from the formation
of spacetime singularities in the limits where the inner horizon itself is
singular, which occur in the Schwarzschild and dilaton black hole limits. The
supersymmetric limit corresponding to the extreme axion-dilaton black hole
yields the Bertotti-Robinson metric with the axion and dilaton fields flowing
to fixed constant values. The maximal analytic extension of this metric across
the Cauchy horizon yields a spacetime in which two sandwich waves in a
cylindrical universe collide to produce a semi-infinite chain of
Reissner-Nordstrom-like wormholes. The focussing of particle and string
geodesics in this spacetime is explored.Comment: 19 pages, 6 figure
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