746 research outputs found
Seeding primordial black holes in multifield inflation
The inflationary origin of primordial black holes (PBHs) relies on a large
enhancement of the power spectrum of the curvature fluctuation
at wavelengths much shorter than those of the cosmic microwave
background anisotropies. This is typically achieved in models where
evolves without interacting significantly with additional (isocurvature) scalar
degrees of freedom. However, quantum gravity inspired models are characterized
by moduli spaces with highly curved geometries and a large number of scalar
fields that could vigorously interact with (as in the cosmological
collider picture). Here we show that isocurvature fluctuations can mix with
inducing large enhancements of its amplitude. This occurs whenever the
inflationary trajectory experiences rapid turns in the field space of the model
leading to amplifications that are exponentially sensitive to the total angle
swept by the turn, which induce characteristic observable signatures on
. We derive accurate analytical predictions and show that the
large enhancements required for PBHs demand non-canonical kinetic terms in the
action of the multifield system.Comment: 7 pages, 1 figure; v2: added clarifications around the analytic
solution and references. Version accepted in PRL; v3: typo corrected, matches
published versio
Identificación de la estructura factorial óptima de la escala de resiliencia de Connor – Davidson en estudiantes universitarios chilenos y su comparación con una muestra de estudiantes universitarios españoles
54 p.La presente investigación se enmarca en la identificación de la estructura factorial óptima de la Escala de Resiliencia CD-RISC (Connor & Davidson, 2003), además de su validación en estudiantes universitarios chilenos, siendo ésta última de gran importancia debido a que es la primera validación de la escala en Chile. De igual forma, se realizará una comparación transcultural en base a una aplicación entre dos poblaciones hispanohablantes; una chilena y una española, de modo que permita esclarecer diferencias significativas frente a la misma aplicación. La primera se aplicó en 396 estudiantes universitarios, mientras que la segunda en 483. Se realizó un análisis factorial exploratorio a fin de determinar su estructura factorial concluyendo que la escala presenta una estructura unidimensional en ambas muestras. Pese a ello, no se pudo verificar la invarianza de medida del modelo unidimensional. En consecuencia, se estimó un modelo bifactor compuesto por un factor general y cinco específicos. En dicho modelo, una vez que se liberaron las cargas de los factores específicos, sí demostró invarianza fuerte entre ambas muestras. Se concluye la unidimensionalidad básica de la escala, además de señalar que únicamente el factor Espiritualidad toma peso como factor específico más allá del factor general de resiliencia
Ten-year follow-up of giant basilar aneurysm treated by sole stenting technique: a case report
<p>Abstract</p> <p>Introduction</p> <p>The sole stenting technique has emerged as a new tool for the management of intracranial aneurysms. However, several concerns have emerged about the long-term behavior of intracranial stents, particularly their safety and efficacy.</p> <p>Case presentation</p> <p>We present the first case of an intracranial aneurysm intentionally treated with the sole stenting technique. After ten years of clinical and imaging follow-up, the lesion has healed and no intrastent stenosis is observed.</p> <p>Several issues concerning this technique are discussed. For instance, the modification of the angle and intra-aneurysmal thrombosis may account as positive effects; negative outcomes include in-stent thrombosis or stenosis.</p> <p>Conclusions</p> <p>This case report, involving a long clinical and imaging follow-up, provides an example of the effectiveness, safety, durability and simplicity of the sole stenting technique in the management of intracranial aneurysms.</p
Absceded abdominal wall desmoid tumor: a case report
Desmoid tumor is a rare type of tumor dependent on a well-differentiated fibroblastic monoclonal proliferation with a high capacity for non-metastatic local invasion, it constitutes <3% of soft tissue neoplasms, an annual incidence of 5-6 cases per million is reported, its etiology is unknown and its clinical presentation depends on the location of the tumor. We presented a case of a 53-year-old female patient who presented to the emergency department with clinical characteristics of abdominal wall abscess with no significant history of its appearance. Abscess drainage plus biopsy of muscle tissue in the anterior region of the abdominal wall was performed, histopathology report compatible with desmoid tumor, radical surgical treatment was decided in a second intervention. Desmoid tumor is rare, since its diagnosis and treatment require a multidisciplinary approach; Active surveillance is currently the treatment of choice for patients who have DD in noncritical locations, and at least 1 to 2 years of active surveillance is now recommended because of its likelihood of spontaneous regression. The main objective of all existing therapies is to preserve or improve the quality of life of the patient
Optical followup of galaxy clusters detected by the South Pole Telescope
The South Pole Telescope (SPT) is a 10 meter telescope operating at mm
wavelengths. It has recently completed a three-band survey covering 2500 sq.
degrees. One of the survey's main goals is to detect galaxy clusters using
Sunyaev-Zeldovich effect and use these clusters for a variety of cosmological
and astrophysical studies such as the dark energy equation of state, the
primordial non-gaussianity and the evolution of galaxy populations. Since 2005,
we have been engaged in a comprehensive optical and near-infrared followup
program (at wavelengths between 0.4 and 5 {\mu}m) to image high-significance
SPT clusters, to measure their photometric redshifts, and to estimate the
contamination rate of the candidate lists. These clusters are then used for
various cosmological and astrophysical studies.Comment: For TAUP 2011 proceeding
Case Notes
For decades, optical time-domain searches have been tuned to find ordinary supernovae, which rise and fall in brightness over a period of weeks. Recently, supernova searches have improved their cadences and a handful of fast-evolving luminous transients have been identified(1-5). These have peak luminosities comparable to type Ia supernovae, but rise to maximum in less than ten days and fade from view in less than one month. Here we present the most extreme example of this class of object thus far: KSN 2015K, with a rise time of only 2.2 days and a time above half-maximum of only 6.8 days. We show that, unlike type Ia supernovae, the light curve of KSN 2015K was not powered by the decay of radioactive elements. We further argue that it is unlikely that it was powered by continuing energy deposition from a central remnant (a magnetar or black hole). Using numerical radiation hydrodynamical models, we show that the light curve of KSN 2015K is well fitted by a model where the supernova runs into external material presumably expelled in a pre-supernova mass-loss episode. The rapid rise of KSN 2015K therefore probes the venting of photons when a hypersonic shock wave breaks out of a dense extended medium.NASA
NNH15ZDA001N
NNX17AI64G
Australian Research Council Centre of Excellence for All-sky Astrophysics
CE11000102
Velocity Segregation and Systematic Biases In Velocity Dispersion Estimates With the SPT-GMOS Spectroscopic Survey
The velocity distribution of galaxies in clusters is not universal; rather,
galaxies are segregated according to their spectral type and relative
luminosity. We examine the velocity distributions of different populations of
galaxies within 89 Sunyaev Zel'dovich (SZ) selected galaxy clusters spanning . Our sample is primarily draw from the SPT-GMOS spectroscopic
survey, supplemented by additional published spectroscopy, resulting in a final
spectroscopic sample of 4148 galaxy spectra---2868 cluster members. The
velocity dispersion of star-forming cluster galaxies is % greater than
that of passive cluster galaxies, and the velocity dispersion of bright () cluster galaxies is % lower than the velocity dispersion of
our total member population. We find good agreement with simulations regarding
the shape of the relationship between the measured velocity dispersion and the
fraction of passive vs. star-forming galaxies used to measure it, but we find a
small offset between this relationship as measured in data and simulations in
which suggests that our dispersions are systematically low by as much as 3\%
relative to simulations. We argue that this offset could be interpreted as a
measurement of the effective velocity bias that describes the ratio of our
observed velocity dispersions and the intrinsic velocity dispersion of dark
matter particles in a published simulation result. Measuring velocity bias in
this way suggests that large spectroscopic surveys can improve dispersion-based
mass-observable scaling relations for cosmology even in the face of velocity
biases, by quantifying and ultimately calibrating them out.Comment: Accepted to ApJ; 21 pages, 11 figures, 5 table
- …