6,108 research outputs found
Phase diagram of Landau-Zener phenomena in coupled one-dimensional Bose quantum fluids
We study stationary and dynamical properties of the many-body Landau-Zener
dynamics of a Bose quantum fluid confined in two coupled one-dimensional
chains, using a many-body generalization recently reported [Y.-A. Chen et al.],
within the decoupling approximation and the one-level band scheme. The energy
spectrum evidences the structure of the avoided level crossings as a function
of the on-site inter particle interaction strength. On the dynamical side, a
phase diagram of the transfer efficiency across ground-state and inverse sweeps
is presented. A totally different scenario with respect to the original
single-particle Landau-Zener scheme is found for ground-state sweeps, in which
a breakdown of the adiabatic region emerges as the sweep rate decreases. On the
contrary, the transfer efficiency across inverse sweeps reveals consistent
results with the single-particle Landau-Zener predictions. In the strong
coupling regime, we find that there is a critical value of the on-site
interaction for which the transfer of particles starts to vanish independently
of the sweep rate. Our results are in qualitative agreement with those of the
experimental counterpart.Comment: 15 pages, submitted to Phys. Rev. A (new version
Physical properties of the gamma-ray binary LS 5039 through low and high frequency radio observations
We have studied in detail the 0.15-15 GHz radio spectrum of the gamma-ray
binary LS 5039 to look for a possible turnover and absorption mechanisms at low
frequencies, and to constrain the physical properties of its emission. We have
analysed two archival VLA monitorings, all the available archival GMRT data and
a coordinated quasi-simultaneous observational campaign conducted in 2013 with
GMRT and WSRT. The data show that the radio emission of LS 5039 is persistent
on day, week and year timescales, with a variability at all
frequencies, and no signature of orbital modulation. The obtained spectra
reveal a power-law shape with a curvature below 5 GHz and a turnover at
GHz, which can be reproduced by a one-zone model with synchrotron
self-absorption plus Razin effect. We obtain a coherent picture for a size of
the emitting region of , setting a magnetic field of
, an electron density of and a mass-loss rate of . These values imply a significant mixing of the stellar wind with the
relativistic plasma outflow from the compact companion. At particular epochs
the Razin effect is negligible, implying changes in the injection and the
electron density or magnetic field. The Razin effect is reported for first time
in a gamma-ray binary, giving further support to the young non-accreting pulsar
scenario.Comment: 16 pages, 9 figures, accepted for publication in MNRA
Deep radio images of the HEGRA and Whipple TeV sources in the Cygnus OB2 region
Context. The modern generation of Cherenkov telescopes has revealed a new
population of gamma-ray sources in the Galaxy. Some of them have been
identified with previously known X-ray binary systems while other remain
without clear counterparts a lower energies. Our initial goal here was
reporting on extensive radio observations of the first extended and yet
unidentified source, namely TeV J2032+4130. This object was originally detected
by the HEGRA telescope in the direction of the Cygnus OB2 region and its nature
has been a matter of debate during the latest years.
Aims. We aim to pursue our radio exploration of the TeV J2032+4130 position
that we initiated in a previous paper but taking now into account the latest
results from new Whipple and MILAGRO TeV telescopes.
Methods. Our investigation is mostly based on interferometric radio
observations with the Giant Metre Wave Radio Telescope (GMRT) close to Pune
(India) and the Very Large Array (VLA) in New Mexico (USA). We also conducted
near infrared observations with the 3.5 m telescope and the OMEGA2000 camera at
the Centro Astronomico Hispano Aleman (CAHA) in Almeria (Spain).
Results. We present deep radio maps centered on the TeV J2032+4130 position
at different wavelengths. In particular, our 49 and 20 cm maps cover a field of
view larger than half a degree that fully includes the Whipple position and the
peak of MILAGRO emission. Our most important result here is a catalogue of 153
radio sources detected at 49 cm within the GMRT antennae primary beam with a
full width half maximum (FWHM) of 43 arc-minute. Moreover, our
multi-configuration VLA images reveal the non-thermal extended emission
previously reported by us with improved angular resolution.Comment: 10 pages, 8 figures, 1 online catalogue. Accepted for publication in
Astronomy & Astrophysic
Intruder configurations in Ne at the transition into the island of inversion: Detailed structure study of Ne
Detailed γ-ray spectroscopy of the exotic neon isotope 28Ne has been performed for the first time using the one-neutron removal reaction from 29Ne on a liquid hydrogen target at 240 MeV/nucleon. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for 28Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N=20 and N=28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chainCEX2020-001007-S, PID2021-127890NB-I0
Neo liberalización y CiudadanÃa(s) en el Sur Global
Introducción La ciudadanÃa: de la Antigüedad a la Modernidad El neoliberalismo y los procesos de neoliberalización Neoliberalización y ciudadanÃas en el Su
Absence of low-energy shape coexistence in 80Ge: The nonobservation of a proposed excited 02+ level at 639 keV
ArtÃculo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UA
Conditional Random Fields as Recurrent Neural Networks
Pixel-level labelling tasks, such as semantic segmentation, play a central
role in image understanding. Recent approaches have attempted to harness the
capabilities of deep learning techniques for image recognition to tackle
pixel-level labelling tasks. One central issue in this methodology is the
limited capacity of deep learning techniques to delineate visual objects. To
solve this problem, we introduce a new form of convolutional neural network
that combines the strengths of Convolutional Neural Networks (CNNs) and
Conditional Random Fields (CRFs)-based probabilistic graphical modelling. To
this end, we formulate mean-field approximate inference for the Conditional
Random Fields with Gaussian pairwise potentials as Recurrent Neural Networks.
This network, called CRF-RNN, is then plugged in as a part of a CNN to obtain a
deep network that has desirable properties of both CNNs and CRFs. Importantly,
our system fully integrates CRF modelling with CNNs, making it possible to
train the whole deep network end-to-end with the usual back-propagation
algorithm, avoiding offline post-processing methods for object delineation. We
apply the proposed method to the problem of semantic image segmentation,
obtaining top results on the challenging Pascal VOC 2012 segmentation
benchmark.Comment: This paper is published in IEEE ICCV 201
Peripheral and central mechanisms involved in hormonal control of male and female reproduction
Reproduction involves the integration of hormonal signals acting across multiple systems togenerate a synchronized physiological output. A critical component of reproduction is the luteinizinghormone (LH) surge, which is mediated by estradiol (E2) and neuroprogesterone interacting tostimulate kisspeptin release in the rostral periventricular nucleus of the third ventricle in rats. Recentevidence has shown that both classical and membrane E2 and progesterone signaling is involved inthis pathway. A metabolite of gonadotropin-releasing hormone (GnRH), GnRH-(1-5), has been shownto stimulate GnRH expression, secretion, and has a role in the regulation of lordosis. Additionally,gonadotropin-inhibitory hormone (GnIH) projects to and influences the activity of GnRH neurons inbirds. Stress-induced changes in GnIH have been shown to alter breeding behaviors in birds,demonstrating another molecular control of reproduction. Peripherally, paracrine and autocrineactions within the gonad have been suggested as therapeutic targets for infertility in both males andfemales. Dysfunction of testicular prostaglandin synthesis is a possible cause of idiopathic maleinfertility. Indeed, local production of melatonin and corticotropin-releasing hormone (CRH) couldinfluence spermatogenesis via immune pathways in the gonad. In females, vascular endothelialgrowth factor A (VEGF-A) has been implicated in an angiogenic process that mediates developmentof the corpus luteum and thus fertility via the Notch signaling pathway. Age-induced decreases infertility involve ovarian kisspeptin and its regulation of ovarian sympathetic innervation. Finally,morphological changes in the arcuate nucleus of the hypothalamus influence female sexualreceptivity in rats. The processes mediating these morphological changes have been shown toinvolve rapid effects of E2 controlling synaptogenesis in this hypothalamic nucleus. Together, thisreview highlights new research in these areas, focusing on recent findings in the molecularmechanisms of central and peripheral hormonal control of reproduction.Fil: Rudolph, L. M.. University of California at Los Angeles; Estados UnidosFil: Bentley, G. E.. University of California Berkeley; Estados UnidosFil: Calandra, Ricardo Saul. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Instituto de BiologÃa y Medicina Experimental. Fundación de Instituto de BiologÃa y Medicina Experimental. Instituto de BiologÃa y Medicina Experimental; ArgentinaFil: Paredes, A. H.. Universidad de Chile; ChileFil: Tesone, Marta. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Instituto de BiologÃa y Medicina Experimental. Fundación de Instituto de BiologÃa y Medicina Experimental. Instituto de BiologÃa y Medicina Experimental; ArgentinaFil: Wu, T. J.. Uniformed Services University; Estados UnidosFil: Micevych, P. E.. University of California at Los Angeles; Estados Unido
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