4,577 research outputs found
Further immunological evidence for the validity of the family Bombinidae (Amphibia Salientia)
New immunological data obtained using Libby’s photron-reflectro- metric technique confirms that Discoglossus belongs to a difíerent family (Discoglossidae Giinther, 1858) from that of Alytes and Bombina (Bombi- nidae Fitzinger, 1826).Nuovi dati immunologici ottenuti con la técnica fotronriflettometrica di Libby confermano che Discoglossus appartiene a una famiglia (Discoglossidae Giinther, 1858) diversa da quella di Alytes e di Bombina (Bombi- nidae Fitzinger, 1826).Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Muse
Further immunological evidence for the validity of the family Bombinidae (Amphibia Salientia)
New immunological data obtained using Libby’s photron-reflectro- metric technique confirms that Discoglossus belongs to a difíerent family (Discoglossidae Giinther, 1858) from that of Alytes and Bombina (Bombi- nidae Fitzinger, 1826).Nuovi dati immunologici ottenuti con la técnica fotronriflettometrica di Libby confermano che Discoglossus appartiene a una famiglia (Discoglossidae Giinther, 1858) diversa da quella di Alytes e di Bombina (Bombi- nidae Fitzinger, 1826).Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Muse
The ultracool dwarf DENIS-P J104814.7-395606. Chromospheres and coronae at the low-mass end of the main-sequence
We have obtained an XMM-Newton observation and a broad-band spectrum from the
ultraviolet to the near infrared with X-Shooter for one of the nearest M9
dwarfs, DENIS-P J1048-3956 (4pc). We integrate these data by a compilation of
activity parameters for ultracool dwarfs from the literature with the aim to
advance our understanding of these objects by comparing them to early-M type
dwarf stars and the Sun.
Our deep XMM-Newton observation has led to the first X-ray detection of
DENIS-P J1048-3956 (log Lx = 25.1) as well as the first measurement of its V
band brightness (V = 17.35mag). Flux-flux relations between X-ray and
chromospheric activity indicators are here for the first time extended into the
regime of the ultracool dwarfs. The approximate agreement of DENIS-P J1048-3956
and other ultracool dwarfs with flux-flux relations for early-M dwarfs suggests
that the same heating mechanisms work in the atmospheres of ultracool dwarfs,
albeit weaker as judged from their lower fluxes. The observed Balmer decrements
of DENIS-P J1048-3956 are compatible with optically thick plasma in LTE at low,
nearly photospheric temperature or optically thin LTE plasma at 20000K.
Describing the decrements with CaseB recombination requires different emitting
regions for Halpha and the higher Balmer lines. The high observed Halpha/Hbeta
flux ratio is also poorly fitted by the optically thin models. We derive a
similarly high value for the Halpha/Hbeta ratio of vB10 and LHS2065 and
conclude that this may be a characteristic of ultracool dwarfs. We add DENIS-P
J1048-3956 to the list of ultracool dwarfs detected in both the radio and the
X-ray band. The Benz-Guedel relation between radio and X-ray luminosity of
late-type stars is well-known to be violated by ultracool dwarfs. We speculate
on the presence of two types of ultracool dwarfs with distinct radio and X-ray
behavior.Comment: accepted for publication in Astronomy & Astrophysic
NASA Langley's Approach to the Sandia's Structural Dynamics Challenge Problem
The objective of this challenge is to develop a data-based probabilistic model of uncertainty to predict the behavior of subsystems (payloads) by themselves and while coupled to a primary (target) system. Although this type of analysis is routinely performed and representative of issues faced in real-world system design and integration, there are still several key technical challenges that must be addressed when analyzing uncertain interconnected systems. For example, one key technical challenge is related to the fact that there is limited data on target configurations. Moreover, it is typical to have multiple data sets from experiments conducted at the subsystem level, but often samples sizes are not sufficient to compute high confidence statistics. In this challenge problem additional constraints are placed as ground rules for the participants. One such rule is that mathematical models of the subsystem are limited to linear approximations of the nonlinear physics of the problem at hand. Also, participants are constrained to use these models and the multiple data sets to make predictions about the target system response under completely different input conditions. Our approach involved initially the screening of several different methods. Three of the ones considered are presented herein. The first one is based on the transformation of the modal data to an orthogonal space where the mean and covariance of the data are matched by the model. The other two approaches worked solutions in physical space where the uncertain parameter set is made of masses, stiffnesses and damping coefficients; one matches confidence intervals of low order moments of the statistics via optimization while the second one uses a Kernel density estimation approach. The paper will touch on all the approaches, lessons learned, validation 1 metrics and their comparison, data quantity restriction, and assumptions/limitations of each approach. Keywords: Probabilistic modeling, model validation, uncertainty quantification, kernel densit
High-accuracy Penning trap mass measurements with stored and cooled exotic ions
The technique of Penning trap mass spectrometry is briefly reviewed
particularly in view of precision experiments on unstable nuclei, performed at
different facilities worldwide. Selected examples of recent results emphasize
the importance of high-precision mass measurements in various fields of
physics
Soret fishnet metalens antenna.
At the expense of frequency narrowing, binary amplitude-only diffractive optical elements emulate refractive
lenses without the need of large profiles. Unfortunately, they also present larger Fresnel reflection loss than
conventional lenses. This is usually tackled by implementing unattractive cumbersome designs. Here we
demonstrate that simplicity is not at odds with performance and we show how the fishnet metamaterial can
improve the radiation pattern of a Soret lens. The building block of this advanced Soret lens is the fishnet
metamaterial operating in the near-zero refractive index regime with one of the edge layers designed with
alternating opaque and transparent concentric rings made of subwavelength holes. The hybrid Soret fishnet
metalens retains all themeritsof classicalSoret lenses suchas lowprofile, lowcost andeaseofmanufacturing. It is
designed for the W-band of themillimeter-waves range with a subwavelength focal lengthFL51.58 mm(0.5l0)
aiming at a compact antenna or radar systems. The focal properties of the lens along with its radiation
characteristics in a lens antenna configuration have been studied numerically and confirmed experimentally,
showing a gain improvement of ,2 dB with respect to a fishnet Soret lens without the fishnet metamaterial.Effort sponsored by Spanish Government under contracts Consolider ‘‘Engineering Metamaterials’’ CSD2008-00066, TEC2011-28664-C02-01. B. O. is sponsored by Spanish Ministerio de Economía y Competitividad under grant FPI BES-2012-054909. M. B. is
sponsored by the Spanish Government via RYC-2011-08221. V.P.-P. is sponsored by Spanish Ministerio de Educación, Cultura y Deporte under grant FPU AP-2012-3796. M. N.-C. is supported by the Imperial College Junior Research Fellowship
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