5,736 research outputs found
SN 2018bsz: A Type I superluminous supernova with aspherical circumstellar material
We present a spectroscopic analysis of the most nearby Type I superluminous supernova (SLSN-I), SN 2018bsz. The photometric evolution of SN 2018bsz has several surprising features, including an unusual pre-peak plateau and evidence for rapid formation of dust greater than or similar to 200 d post-peak. We show here that the spectroscopic and polarimetric properties of SN 2018bsz are also unique. While its spectroscopic evolution closely resembles SLSNe-I, with early O II absorption and C II P Cygni profiles followed by Ca, Mg, Fe, and other O features, a multi-component H alpha profile appearing at similar to 30 d post-maximum is the most atypical. The H alpha is at first characterised by two emission components, one at similar to+3000 km s(-1) and a second at similar to - 7500 km s(-1), with a third, near-zero-velocity component appearing after a delay. The blue and central components can be described by Gaussian profiles of intermediate width (FWHM similar to 2000-6000 km s(-1)), but the red component is significantly broader (FWHM greater than or similar to 10000 km s(-1)) and Lorentzian. The blue H alpha component evolves towards a lower-velocity offset before abruptly fading at similar to + 100 d post-maximum brightness, concurrently with a light curve break. Multi-component profiles are observed in other hydrogen lines, including Pa beta, and in lines of Ca II and He I. Spectropolarimetry obtained before (10.2 d) and after (38.4 d) the appearance of the H lines shows a large shift on the Stokes Q - U plane consistent with SN 2018bsz undergoing radical changes in its projected geometry. Assuming the supernova is almost unpolarised at 10.2 d, the continuum polarisation at 38.4 d reaches P similar to 1.8%, implying an aspherical configuration. We propose that the observed evolution of SN 2018bsz can be explained by highly aspherical, possibly disk-like, circumstellar material (CSM) with several emitting regions. After the supernova explosion, the CSM is quickly overtaken by the ejecta, but as the photosphere starts to recede, the different CSM regions re-emerge, producing the peculiar line profiles. Based on the first appearance of H alpha, we can constrain the distance of the CSM to be less than similar to 6.5 x 10(15) cm (430 AU), or even lower (less than or similar to 87 AU) if the pre-peak plateau is related to an eruption that created the CSM. The presence of CSM has been inferred previously for other SLSNe-I, both directly and indirectly. However, it is not clear whether the rare properties of SN 2018bsz can be generalised for SLSNe-I, for example in the context of pulsational pair instability, or whether they are the result of an uncommon evolutionary path, possibly involving a binary companion.European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 2101.D-5023Villum Fonden 19054Science Foundation IrelandEuropean CommissionRoyal Society of LondonEuropean Commission RS-EA/3471Swedish Research CouncilEuropean Commission 2020-03330National Agency for Research and Development (ANID)/Scholarship Program/Doctorado Nacional 2021 - 21211203European Commission H2020-MSCA-IF-2018-842471Science Foundation IrelandMinistry of Science and Innovation, Spain (MICINN)Agencia Estatal de Investigacion (AEI)European Social Fund (ESF) "Investing in your future" under the 2019 Ramon y Cajal program RYC2019-027683-ICentro Superior de Investigaciones Cientificas (CSIC) 20215AT016program Unidad de Excelencia Maria de Maeztu CEX2020-001058-MEU Horizon 2020 research and innovation programme 101004719European Research Council (ERC)European Commission 948381Alan Turing InstituteGRAWITA/PRIN-MIUR project: "The new frontier of the Multi-Messenger Astrophysics: follow-up of electromagnetic transient counterparts of gravitational wave sources"HORIZON2020: AHEAD2020 871158
1103.D-0328
PID2020-115253GA-I00 HOSTFLOWS Swedish Research CouncilEuropean Commission 2020-03330National Agency for Research and Development (ANID)/Scholarship Program/Doctorado Nacional 2021 - 21211203European Commission H2020-MSCA-IF-2018-842471Science Foundation IrelandMinistry of Science and Innovation, Spain (MICINN)Agencia Estatal de Investigacion (AEI)European Social Fund (ESF) "Investing in your future" under the 2019 Ramon y Cajal program RYC2019-027683-ICentro Superior de Investigaciones Cientificas (CSIC) 20215AT016program Unidad de Excelencia Maria de Maeztu CEX2020-001058-MEU Horizon 2020 research and innovation programme 101004719European Research Council (ERC)
European Commission 948381Alan Turing InstituteGRAWITA/PRIN-MIUR project: "The new frontier of the Multi-Messenger Astrophysics: follow-up of electromagnetic transient counterparts of gravitational wave sources"HORIZON2020: AHEAD2020 871158
1103.D-0328
PID2020-115253GA-I00 HOSTFLOW
Decoherence in a double-slit quantum eraser
We study and experimentally implement a double-slit quantum eraser in the
presence of a controlled decoherence mechanism. A two-photon state, produced in
a spontaneous parametric down conversion process, is prepared in a maximally
entangled polarization state. A birefringent double-slit is illuminated by one
of the down-converted photons, and it acts as a single-photon two-qubits
controlled not gate that couples the polarization with the transversal momentum
of these photons. The other photon, that acts as a which-path marker, is sent
through a Mach-Zehnder-like interferometer. When the interferometer is
partially unbalanced, it behaves as a controlled source of decoherence for
polarization states of down-converted photons. We show the transition from
wave-like to particle-like behavior of the signal photons crossing the
double-slit as a function of the decoherence parameter, which depends on the
length path difference at the interferometer.Comment: Accepted in Physical Review
Optimal high-dimensional entanglement concentration in the bipartite scenario
Considering pure quantum states, entanglement concentration is the procedure
where from copies of a partially entangled state, a single state with
higher entanglement can be obtained. Getting a maximally entangled state is
possible for . However, the associated success probability can be
extremely low while increasing the system's dimensionality. In this work, we
study two methods to achieve a probabilistic entanglement concentration for
bipartite quantum systems with a large dimensionality for , regarding a
reasonably good probability of success at the expense of having a non-maximal
entanglement. Firstly, we define an efficiency function
considering a tradeoff between the amount of entanglement (quantified by the
I-Concurrence) of the final state after the concentration procedure and its
success probability, which leads to solving a quadratic optimization problem.
We found an analytical solution, ensuring that an optimal scheme for
entanglement concentration can always be found in terms of .
Finally, a second method was explored, which is based on fixing the success
probability and searching for the maximum amount of entanglement attainable.
Both ways resemble the Procrustean method applied to a subset of the most
significant Schmidt coefficients but obtaining non-maximally entangled states.Comment: 11 pages, 4 figure
Ensemble and Greedy Approach for the Reconstruction of Large Gene Co-Expression Networks
In the recent years, the vast amount of genetic information generated by high-throughput approaches, have led to the need of new methods for data handling. The integrative analysis of diverse-nature gene information could provide a much-sought overview to study complex biological systems and processes. In this sense, Co-expression Gene Networks (CGN) have become a powerful tool in the comprehensive analysis of gene expression. Such networks represent relationships between genes (or gene products) by means of a graph composed of nodes and edges, where nodes represent genes and edges the relationships among them. Amongst the main features of CGN, sparseness and scale-free topology may notably affect the latter network analysis. Within this framework, structure optimization techniques are also important in the reduction of the size of the networks, not only improving their topology but also keeping a positive prediction ratio. On the other hand, ensemble strategies have significantly improved the precision of results by combining different measures or methods.
In this work, we present Ensemble and Greedy networks (EnGNet), a novel two-step method for CGN inference. First, EnGNet uses an ensemble strategy for co-expression networks generation. Final score is estimated by major voting among three different methdos, i.e. Spearman and Kendall coefficients and Normalized Mutual Information. Second, a greedy algorithm optimizes both the size and the topological features of the network. Not only do achieved results show that this method is able to obtain reliable networks, but also that it significantly improves the topology of the networks.
Moreover, the usefulness of the method is proven by an application to a human dataset on post-traumatic stress disorder (PTSD), revealing an innate immunity-mediated response to this pathology in accordance with previous studies. These results are indicative of the potential of CGN, and EnGNet in particular, in the unveiling of the genetic causes for complex diseases. Finally, the implications of CGN in biomarkers discovery, could lead research towards earlier detection and effective treatment of these diseases
The Low Redshift survey at Calar Alto (LoRCA)
The Baryon Acoustic Oscillation (BAO) feature in the power spectrum of
galaxies provides a standard ruler to measure the accelerated expansion of the
Universe. To extract all available information about dark energy, it is
necessary to measure a standard ruler in the local, z<0.2, universe where dark
energy dominates most the energy density of the Universe. Though the volume
available in the local universe is limited, it is just big enough to measure
accurately the long 100 Mpc/h wave-mode of the BAO. Using cosmological N-body
simulations and approximate methods based on Lagrangian perturbation theory, we
construct a suite of a thousand light-cones to evaluate the precision at which
one can measure the BAO standard ruler in the local universe. We find that
using the most massive galaxies on the full sky (34,000 sq. deg.), i.e. a
K(2MASS)<14 magnitude-limited sample, one can measure the BAO scale up to a
precision of 4\% and 1.2\% using reconstruction). We also find that such a
survey would help to detect the dynamics of dark energy.Therefore, we propose a
3-year long observational project, named the Low Redshift survey at Calar Alto
(LoRCA), to observe spectroscopically about 200,000 galaxies in the northern
sky to contribute to the construction of aforementioned galaxy sample. The
suite of light-cones is made available to the public.Comment: 15 pages. Accepted in MNRAS. Please visit our website:
http://lorca-survey.ft.uam.es
The Low Redshift survey at Calar Alto (LoRCA)
The Baryon Acoustic Oscillation (BAO) feature in the power spectrum of
galaxies provides a standard ruler to measure the accelerated expansion of the
Universe. To extract all available information about dark energy, it is
necessary to measure a standard ruler in the local, z<0.2, universe where dark
energy dominates most the energy density of the Universe. Though the volume
available in the local universe is limited, it is just big enough to measure
accurately the long 100 Mpc/h wave-mode of the BAO. Using cosmological N-body
simulations and approximate methods based on Lagrangian perturbation theory, we
construct a suite of a thousand light-cones to evaluate the precision at which
one can measure the BAO standard ruler in the local universe. We find that
using the most massive galaxies on the full sky (34,000 sq. deg.), i.e. a
K(2MASS)<14 magnitude-limited sample, one can measure the BAO scale up to a
precision of 4\% and 1.2\% using reconstruction). We also find that such a
survey would help to detect the dynamics of dark energy.Therefore, we propose a
3-year long observational project, named the Low Redshift survey at Calar Alto
(LoRCA), to observe spectroscopically about 200,000 galaxies in the northern
sky to contribute to the construction of aforementioned galaxy sample. The
suite of light-cones is made available to the public.Comment: 15 pages. Accepted in MNRAS. Please visit our website:
http://lorca-survey.ft.uam.es
Extreme Starbursts in the Local Universe
The "Extreme starbursts in the local universe" workshop was held at the
Insituto de Astrofisica de Andalucia in Granada, Spain on 21-25 June 2010.
Bearing in mind the advent of a new generation of facilities such as JWST,
Herschel, ALMA, eVLA and eMerlin, the aim of the workshop was to bring together
observers and theorists to review the latest results. The purpose of the
workshop was to address the following issues: what are the main modes of
triggering extreme starbursts in the local Universe? How efficiently are stars
formed in extreme starbursts? What are the star formation histories of local
starburst galaxies? How well do the theoretical simulations model the
observations? What can we learn about starbursts in the distant Universe
through studies of their local counterparts? How important is the role of
extreme starbursts in the hierarchical assembly of galaxies? How are extreme
starbursts related to the triggering of AGN in the nuclei of galaxies? Overall,
41 talks and 4 posters with their corresponding 10 minutes short talks were
presented during the workshop. In addition, the workshop was designed with
emphasis on discussions, and therefore, there were 6 discussion sessions of up
to one hour during the workshop. Here is presented a summary of the purposes of
the workshop as well as a compilation of the abstracts corresponding to each of
the presentations. The summary and conclusions of the workshop along with a
description of the future prospects by Sylvain Veilleux can be found in the
last section of this document. A photo of the assistants is included.Comment: worksho
Generalized thermodynamics of q-deformed bosons and fermions
We study the thermostatistics of q-deformed bosons and fermions obeying the
symmetric algebra and show that it can be built on the formalism of q-calculus.
The entire structure of thermodynamics is preserved if ordinary derivatives are
replaced by an appropriate Jackson derivative. In this framework, we derive the
most important thermodynamic functions describing the q-boson and q-fermion
ideal gases in the thermodynamic limit. We also investigate the semi-classical
limit and the low temperature regime and demonstrate that the nature of the
q-deformation gives rise to pure quantum statistical effects stronger than
undeformed boson and fermion particles.Comment: 8 pages, Physical Review E in pres
Integral field spectroscopy of type-II QSOs at z=0.3-0.4
We present and analyse integral-field observations of six type-II QSOs with
z=0.3-0.4, selected from the Sloan Digital Sky Survey (SDSS). Two of our sample
are found to be surrounded by a nebula of warm ionized gas, with the largest
nebula extending across 8" (40 kpc). Some regions of the extended nebulae show
kinematics that are consistent with gravitational motion, while other regions
show relatively perturbed kinematics: velocity shifts and line widths too large
to be readily explained by gravitational motion. We propose that a ~20 kpc x20
kpc outflow is present in one of the galaxies. Possible mechanisms for
triggering the outflow are discussed. In this object, we also find evidence for
ionization both by shocks and the radiation field of the AGN.Comment: 6 pages, 5 figures, accepted by MNRAS Letter
18F-FDG PET/CT in breast cancer: Evidence-based recommendations in initial staging
Current guidelines do not systematically recommend 18F-FDG PET/CT for breast cancer staging; and the recommendations and level of evidence supporting its use in different groups of patients vary among guidelines. This review summarizes the evidence about the role of 18F-FDG PET/CT in breast cancer staging and the therapeutic and prognostic impact accumulated in the last decade. Other related aspects, such as the association of metabolic information with biology and prognosis are considered and evidence-based recommendations for the use of 18F-FDG PET/CT in breast cancer staging are offered. We systematically searched MEDLINE for articles reporting studies with at least 30 patients related to clinical questions following the Problem/Population, Intervention, Comparison, and Outcome framework. We critically reviewed the selected articles and elaborated evidence tables structuring the summarized information into methodology, results, and limitations. The level of evidence and the grades of recommendation for the use of 18F-FDG PET/CT in different contexts are summarized. Level III evidence supports the use of 18F-FDG PET/CT for initial staging in patients with recently diagnosed breast cancer; the diagnostic and therapeutic impact of the 18F-FDG PET/CT findings is sufficient for a weak recommendation in this population. In patients with locally advanced breast cancer, level II evidence supports the use of 18F-FDG PET/CT for initial staging; the diagnostic and therapeutic impact of the 18F-FDG PET/CT findings is sufficient for a strong recommendation in this population. In patients with recently diagnosed breast cancer, the metabolic information from baseline 18F-FDG PET/CT is associated with tumor biology and has prognostic implications, supported by level II evidence. In conclusion, 18F-FDG PET/CT is not recommended for staging all patients with early breast cancer, although evidence of improved regional and systemic staging supports its use in locally advanced breast cancer. Baseline tumor glycolytic activity is associated with tumor biology and prognosis
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