22,593 research outputs found
The Dunford-Pettis property on tensor products
We show that, in some cases, the projective and the injective tensor products
of two Banach spaces do not have the Dunford-Pettis property (DPP). As a
consequence, we obtain that fails the DPP.
Since does enjoy it, this provides a new space
with the DPP whose dual fails to have it. We also prove that, if and
are -spaces, then has the DPP if
and only if both and have the Schur property. Other results and
examples are given.Comment: 9 page
A Method to Separate Stochastic and Deterministic Information from Electrocardiograms
In this work we present a new idea to develop a method to separate stochastic
and deterministic information contained in an electrocardiogram, ECG, which may
provide new sources of information with diagnostic purposes. We assume that the
ECG has information corresponding to many different processes related with the
cardiac activity as well as contamination from different sources related with
the measurement procedure and the nature of the observed system itself. The
method starts with the application of an improuved archetypal analysis to
separate the mentioned stochastic and deterministic information. From the
stochastic point of view we analyze Renyi entropies, and with respect to the
deterministic perspective we calculate the autocorrelation function and the
corresponding correlation time. We show that healthy and pathologic information
may be stochastic and/or deterministic, can be identified by different measures
and located in different parts of the ECG.Comment: 4 pages, 6 figure
Surjective factorization of holomorphic mappings
We characterize the holomorphic mappings between complex Banach spaces
that may be written in the form , where is another holomorphic
mapping and belongs to a closed surjective operator ideal.Comment: 8 page
Description and molecular phylogeny of a new and one known needle nematode of the genus Paralongidorus (Nematoda: Longidoridae) from grapevine in Portugal
A new and a known longidorid nematode, Paralongidorus lusitanicus n. sp. and Paralongidorus plesioepimikis, are described and illustrated from populations extracted from soil associated with grapevine (Vitis vinifera L.) from Escaroupim and Pó (central-Western Portugal), respectively. The new needle nematode P. lusitanicus n. sp. is characterised by a very large body size (8072–12,022 μm), an expanded and rounded lip region, ca 30 μm wide, with a clear constriction followed by a depression posterior to the amphidial aperture, amphidial fovea very large (11.0–19.0 μm), stirrup-shaped, with conspicuous slit-like aperture as shown in scanning electron microscopy studies, a very long and flexible odontostyle (180.0–223.0 μm), guiding ring located at 28.0–41.5 μm from anterior end, vulva anterior to the mid-body (34–41%), a dorsally convex-conoid tail with rounded terminus (29–42 μm long), bearing two or three pairs of caudal pores and males common (ratio 1:1.6 females) with spicules ca 80 μm long. Morphological and morphometric traits for P. plesioepimikis fit well with the original description, and is reported for the first time in Portugal. Integrative diagnosis of both species was completed with molecular data obtained using D2-D3 expansion segments of 28S rDNA, ITS1-rDNA and partial 18S–rDNA. The phylogenetic relationships of these species with other Paralongidorus spp. using these three molecular markers indicated that P. lusitanicus n. sp. clustered together with other Paralongidorus spp. forming a sister clade with P. plesioepimikis, both of them sharing a large body, long odontostyle, an anteriorly located vulva and an expanded and rounded lip region with a clear constriction followed by a depression posterior to the amphidial aperture
The value of the fine structure constant over cosmological times
The optical spectra of objects classified as QSOs in the SDSS DR6 are
analyzed with the aim of determining the value of the fine structure constant
in the past and then check for possible changes in the constant over
cosmological timescales. The analysis is done by measuring the position of the
fine structure lines of the [OIII] doublet (4959 and 5008) in QSO nebular
emission. From the sample of QSOs at redshifts z < 0.8 a subsample was selected
on the basis of the amplitude and width of the [OIII] lines. Two different
method were used to determine the position of the lines of the [OIII] doublet,
both giving similar results. Using a clean sample containing 1568 of such
spectra, a value of Delta alpha /alpha=(+2.4 +-2.5) x 10^{-5} (in the range of
redshifts 0-0.8) was determined. The use of a larger number of spectra allows a
factor ~5 improvement on previous constraints based on the same method. On the
whole, we find no evidence of changes in alpha on such cosmological timescales.
The mean variation compatible with our results is 1/ Delta
alpha/alpha=(+0.7 +- 0.7) x 10^{-14} yr^{-1}. The analysis was extended to the
[NeIII] and [SII] doublets, although their usefulness is limited due to the
fact that all these doublets in QSOs tend to be fainter than [OIII], and that
some of them are affected by systematics.Comment: 22 pages, 10 figures. Accepted for publication in Astrophysical
Journa
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