1,237 research outputs found
Towards a Universal Semantic Dictionary
[EN] A novel method for finding linear mappings among word embeddings for several languages, taking as pivot a shared, multilingual embedding space, is proposed in this paper. Previous approaches learned translation matrices between two specific languages, while this method learns translation matrices between a given language and a shared, multilingual space. The system was first trained on bilingual, and later on multilingual corpora as well. In the first case, two different training data were applied: Dinu¿s English¿Italian benchmark data, and English¿Italian translation pairs extracted from the PanLex database. In the second case, only the PanLex database was used. The system performs on English¿Italian languages with the best setting significantly better than the baseline system given by Mikolov, and it provides a comparable performance with more sophisticated systems. Exploiting the richness of the PanLex database, the proposed method makes it possible to learn linear mappings among an arbitrary number of languages.This research was funded by Spanish MINECO and FEDER grant number TIN2017-85854-C4-2-R.Castro-Bleda, MJ.; Iklódi, E.; Recski, G.; Borbély, G. (2019). Towards a Universal Semantic Dictionary. Applied Sciences. 9(19):1-14. https://doi.org/10.3390/app9194060S114919Youn, H., Sutton, L., Smith, E., Moore, C., Wilkins, J. F., Maddieson, I., … Bhattacharya, T. (2016). On the universal structure of human lexical semantics. Proceedings of the National Academy of Sciences, 113(7), 1766-1771. doi:10.1073/pnas.1520752113Ruder, S., Vulić, I., & Søgaard, A. (2019). A Survey of Cross-lingual Word Embedding Models. Journal of Artificial Intelligence Research, 65, 569-631. doi:10.1613/jair.1.11640Bojanowski, P., Grave, E., Joulin, A., & Mikolov, T. (2017). Enriching Word Vectors with Subword Information. Transactions of the Association for Computational Linguistics, 5, 135-146. doi:10.1162/tacl_a_0005
Photoelectron holography of atomic targets
We study the spatial interference effects appearing during the ionization of atoms (H, He, Ne, and Ar) by few-cycle laser pulses using single-electron ab initio calculations. The spatial interference is the result of the coherent superposition of the electronic wave packets created during one half cycle of the driving field following different spatial paths. This spatial interference pattern may be interpreted as the hologram of the target atom. With the help of a wave-function analysis (splitting) technique and approximate (strong-field and Coulomb-Volkov) calculations, we directly show that the hologram is the result of the electronic-wave-packet scattering on the parent ion. On the He target we demonstrate the usefulness of the wave-function splitting technique in the disentanglement of different interference patterns. Further, by performing calculations for the different targets, we show that the pattern of the hologram does not depend on the angular symmetry of the initial state and it is strongly influenced by the atomic species of the target: A deeper bounding potential leads to a denser pattern.Fil: Borbély, S.. Babes Bolyai University; RumaniaFil: Tóth, A.. ELI-HU Nonprofit Ltd; HungríaFil: Arbo, Diego. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Tokési, K.. ELI-HU Nonprofit Ltd; Hungría. Hungarian Academy of Sciences. Institute for Nuclear Research; HungríaFil: Nagy, L.. Babes-bolyai University; Rumani
Ionization of the hydrogen atom by intense ultrashort laser pulses
The ionization of atomic hydrogen in intense laser fields is studied
theoretically. The calculations were performed applying both quantummechanical
and classical approaches. Treating the problem quantummechanically, the time
dependent Schr\"odinger equation (TDSE) of our system was first transformed
into a pseudo-momentum space and solved in this space iteratively. While
neglecting the Coulomb potential during the solution of the TDSE we got the
results in the Volkov approximation, in the first order solution we taken into
account the Coulomb potential as perturbation. The classical calculations were
performed within the framework of the classical trajectory Monte-Carlo (CTMC)
method.
The double differential ionization probabilities are calculated for different
laser pulses and a reasonable agreement was found between the theories. Major
differences can be observed in the angular distribution of electrons at low
electron energies between classical and the quantummechanical approaches. At
high electron energies the differences disappear, which indicates that the
generation of low energy electrons is of quantum type, and it is strongly
influenced by the Coulomb potential, while the production of high energy
electrons is of classical type and it is less influenced by the Coulomb
interaction. Our results are also compared with the Coulomb-Volkov (CV) model
calculations.Comment: submited to PR
Communications Biophysics
Contains reports on four research projects.National Institutes of Health (Grant 1 P01 GM-14940-02)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E)National Institutes of Health (Grant 5 TO1 GM-01555-02
Correlation Between the Deuteron Characteristics and the Low-energy Triplet np Scattering Parameters
The correlation relationship between the deuteron asymptotic normalization
constant, , and the triplet np scattering length, , is
investigated. It is found that 99.7% of the asymptotic constant is
determined by the scattering length . It is shown that the linear
correlation relationship between the quantities and
provides a good test of correctness of various models of nucleon-nucleon
interaction. It is revealed that, for the normalization constant and
for the root-mean-square deuteron radius , the results obtained with the
experimental value recommended at present for the triplet scattering length
are exaggerated with respect to their experimental counterparts. By
using the latest experimental phase shifts of Arndt et al., we obtain, for the
low-energy scattering parameters (, , ) and for the
deuteron characteristics (, ), results that comply well with
experimental data.Comment: 19 pages, 1 figure, To be published in Physics of Atomic Nucle
n-Heptane hydroconversion over nickel-loaded aluminum- and/or boron-containing BEA zeolites prepared by recrystallization of magadiite varieties
Phase-pure [Al]BEA and [Al,B]BEA zeolites, prepared by solid-state recrystallization of synthetic aluminum-containing magadiites and conventionally synthesized [B]BEA, were tested, after ion exchange with nickel, as bifunctional catalysts for hydroconversion of n-heptane. The reducibility of nickel ions incorporated into BEA zeolites by ion exchange was investigated by temperature-programmed reduction (TPR). The acidity of the samples was characterized with strong (pyridine (Py), ammonia (NH3)) and weak (nitrogen) bases. The adsorbed bases were studied by transmission FT-IR (Py), diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy (N2), and temperature-programmed ammonia evolution (TPAE, NH3). Over Ni/H-[B]BEA the reactants were completely converted via fast hydrogenolysis, whereas this reaction pathway plays only a negligible role in the hydroconversion over Ni/H-[Al]BEA and Ni/H-[Al,B]BEA zeolites. Boron-containing BEA zeolites were less active catalysts than the boron-free catalyst in the principal unimolecular hydroconversion reactions. However, incorporation of boron into the framework of BEA zeolite results in a considerable selectivity shift towards isomerization. Results suggest that the acid strength of bridged hydroxyls, probed with weak (N2) and strong basis (pyridine), was found to be similar in the boron-free and boron-containing BEA samples. The decrease in the isomerization rate and the increase of the apparent activation energy upon incorporation of boron may be attributed to the decrease in the heat of n-heptane adsorption
Single acute stress-induced progesterone and ovariectomy alter cardiomyocyte contractile function in female rats
Aim To assess how ovarian-derived sex hormones (in particular
progesterone) modify the effects of single acute
stress on the mechanical and biochemical properties of
left ventricular cardiomyocytes in the rat.
Methods Non-ovariectomized (control, n = 8) and ovariectomized
(OVX, n = 8) female rats were kept under normal
conditions or were exposed to stress (control-S, n = 8
and OVX-S, n = 8). Serum progesterone levels were measured
using a chemiluminescent immunoassay. Left ventricular
myocardial samples were used for isometric force
measurements and protein analysis. Ca2+-dependent active
force (Factive), Ca2+-independent passive force (Fpassive),
and Ca2+-sensitivity of force production were determined
in single, mechanically isolated, permeabilized cardiomyocytes.
Stress- and ovariectomy-induced alterations in myofilament
proteins (myosin-binding protein C [MyBP-C], troponin
I [TnI], and titin) were analyzed by sodium dodecyl
sulfate gel electrophoresis using protein and phosphoprotein
stainings. Results Serum progesterone levels were significantly increased
in stressed rats (control-S, 35.6 ± 4.8 ng/mL and
OVX-S, 21.9 ± 4.0 ng/mL) compared to control (10 ± 2.9
ng/mL) and OVX (2.8 ± 0.5 ng/mL) groups. Factive was higher
in the OVX groups (OVX, 25.9 ± 3.4 kN/m2 and OVX-S,
26.3 ± 3.0 kN/m2) than in control groups (control, 16.4 ± 1.2
kN/m2 and control-S, 14.4 ± 0.9 kN/m2). Regarding the
potential molecular mechanisms, Factive correlated with
MyBP-C phosphorylation, while myofilament Ca2+-sensitivity
inversely correlated with serum progesterone levels
when the mean values were plotted for all animal groups.
Fpassive was unaffected by any treatment.
Conclusion Stress increases ovary-independent synthesis
and release of progesterone, which may regulate Ca2+-sensitivity
of force production in left ventricular cardiomyocytes.
Stress and female hormones differently alter Ca2+-
dependent cardiomyocyte contractile force production,
which may have pathophysiological importance during
stress conditions affecting postmenopausal women
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