891 research outputs found
A statistical approach to identify superluminous supernovae and probe their diversity
We investigate the identification of hydrogen-poor superluminous supernovae
(SLSNe I) using a photometric analysis, without including an arbitrary
magnitude threshold. We assemble a homogeneous sample of previously classified
SLSNe I from the literature, and fit their light curves using Gaussian
processes. From the fits, we identify four photometric parameters that have a
high statistical significance when correlated, and combine them in a parameter
space that conveys information on their luminosity and color evolution. This
parameter space presents a new definition for SLSNe I, which can be used to
analyse existing and future transient datasets. We find that 90% of previously
classified SLSNe I meet our new definition. We also examine the evidence for
two subclasses of SLSNe I, combining their photometric evolution with
spectroscopic information, namely the photospheric velocity and its gradient. A
cluster analysis reveals the presence of two distinct groups. `Fast' SLSNe show
fast light curves and color evolution, large velocities, and a large velocity
gradient. `Slow' SLSNe show slow light curve and color evolution, small
expansion velocities, and an almost non-existent velocity gradient. Finally, we
discuss the impact of our analyses in the understanding of the powering engine
of SLSNe, and their implementation as cosmological probes in current and future
surveys.Comment: 16 pages, 9 figures, accepted by ApJ on 23/01/201
Solâgel-entrapped pH indicator for monitoring pH variations in cementitious materials
Sensors for pH evaluation of concrete were made by a solâgel process with alizarin yellow as pH indicator. The optical absorbance was measured with a visible spectrophotometer coupled with optical fibers. Results showed that the sensors had good reversibility, reproducibility, and fast response time
Moderately Luminous type II Supernovae
Core-collapse Supernovae (CC-SNe) descend from progenitors more massive than
about 8 Msun. Because of the young age of the progenitors, the ejecta may
eventually interact with the circumstellar medium (CSM) via highly energetic
processes detectable in the radio, X-ray, ultraviolet (UV) and, sometimes, in
the optical domains. In this paper we present ultraviolet, optical and near
infrared observations of five type II SNe, namely SNe 2009dd, 2007pk, 2010aj,
1995ad, and 1996W. Together with few other SNe they form a group of moderately
luminous type II events. We collected photometry and spectroscopy with several
telescopes in order to construct well-sampled light curves and spectral
evolutions from the photospheric to the nebular phases. Both photometry and
spectroscopy indicate a degree of heterogeneity in this sample. The light
curves have luminous peak magnitudes (). The ejected
masses of ^56\ni for three SNe span a wide range of values
(MsunM(\ni)Msun), while for a fourth
(SN2010aj) we could determine a stringent upper limit (Msun).
Clues of interaction, such as the presence of high velocity (HV) features of
the Balmer lines, are visible in the photospheric spectra of SNe 2009dd and
1996W. For SN2007pk we observe a spectral transition from a type IIn to a
standard type II SN. Modelling the observations of SNe 2009dd, 2010aj and
1995ad with radiation hydrodynamics codes, we infer kinetic plus thermal
energies of about 0.2-0.5 foe, initial radii of 2-5 cm and
ejected masses of 5.0-9.5 Msun. These values suggest moderate-mass,
super-asymptotic giant branch (SAGB) or red super-giants (RSG) stars as SN
precursors, in analogy with other luminous type IIP SNe 2007od and 2009bw.Comment: 28 pages, 27 fig, accepted by A&A, 3 pages of online material,
abstract abridged. revised significantly with respect to the previous versio
Advanced 3D âModelingâ and âPrintingâ for the Surgical Planning of a Successful Case of Thoraco-Omphalopagus Conjoined Twins Separation
The surgical separation of two Conjoined Twins is a particularly complex operation. Surgical times are particularly long and post-operative complications are very frequent in this type of procedure. We report a clinical case of surgical separation of two thoraco-omphalopagus conjoined twins in which, thanks to the use of (3D) three dimensional technologies, we were able to significantly reduce operative times and improve clinical outcomes
The Type IIP SN 2007od in UGC 12846: from a bright maximum to dust formation in the nebular phase
Ultraviolet (UV), optical and near infrared (NIR) observations of the type
IIP supernova (SN) 2007od are presented, covering from the maximum light to the
late phase, allowing to investigate in detail different physical phenomena in
the expanding ejecta. These data turn this object into one of the most peculiar
IIP ever studied. The early light curve of SN 2007od is similar to that of a
bright IIPs with a short plateau, a bright peak (MV = -18 mag), but a very
faint optical light curve at late time. However, with the inclusion of mid
infrared (MIR) observations during the radioactive decay we have estimate a
M(56Ni) ~ 2\times10^-2 M\odot. Modeling the bolometric light curve, ejecta
expansion velocities and black-body temperature, we estimate a total ejected
mass was 5 - 7.5 M\odot with a kinetic energy of at least 0.5 \times 10^51 erg.
The early spectra reveal a boxy H{\alpha} profile and high velocities features
of the Balmer series that suggest interaction between the ejecta and a close
circum-stellar matter (CSM). SN 2007od may be, therefore, an intermediate case
between a Type IIn SN and a typical Type IIP SN. Also late spectra show a clear
evidence of CSM and the presence of dust formed inside the ejecta. The episodes
of mass loss short before explosion, the bright plateau, along with the
relatively small amount of 56Ni and the faint [O I] observed in the nebular
spectra are consistent with a super-asympthotic giant branch (super-AGB)
progenitor (M~9.7 - 11 M\odot).Comment: V2, some test added and three figures changed from the first version.
21 pages, 18 figures, accepted for publication in MNRAS on May 24, 201
Supernova 2012ec: Identification of the progenitor and early monitoring with PESSTO
We present the identification of the progenitor of the Type IIP SN 2012ec in
archival pre-explosion HST WFPC2 and ACS/WFC F814W images. The properties of
the progenitor are further constrained by non-detections in pre-explosion WFPC2
F450W and F606W images. We report a series of early photometric and
spectroscopic observations of SN 2012ec. The r'-band light curve shows a
plateau with M(r')=-17.0. The early spectrum is similar to the Type IIP SN
1999em, with the expansion velocity measured at Halpha absorption minimum of
-11,700 km/s (at 1 day post-discovery). The photometric and spectroscopic
evolution of SN 2012ec shows it to be a Type IIP SN, discovered only a few days
post-explosion (<6d). We derive a luminosity for the progenitor, in comparison
with MARCS model SEDs, of log L/Lsun = 5.15+/-0.19, from which we infer an
initial mass range of 14-22Msun. This is the first SN with an identified
progenitor to be followed by the Public ESO Spectroscopic Survey of Transient
Objects (PESSTO).Comment: 6 pages, 3 figures, MNRAS accepte
SURGERY IN PATIENTS WITH TESTICULAR MALIGNANT GERM CELL TUMORS: COMPLIANCE TO SURGICAL GUIDELINES AND RESULTS IN THE ITALIAN COOPERATIVE STUDY
Purpose:
Surgery represents a main and often the only treatment in patients with testicular Malignant Germ Cell Tumors (MGCT). We analyzed the compliance to surgical guidelines and the results in a series of patients with testicular MGCT -/+ retroperitoneal node involvement, without distant metastases.
Method:
42 patients, observed in 15 Centers were enrolled in the Italian Cooperative Study on MGCT (January2004âDecember2010). 14/42 were younger than 2 y. of age, 28/42 between 13â18 y. Treatment was delivered according to COG-Staging-System: St.I patients (complete excision with inguinal orchifunicolectomy+decrease of markers, +hemiscrotectomy if scrotal involvement) did not receive further treatment; St.II patients (scrotal involvement after hemiscrotectomy and/or retroperitoneal node (RPN) enlargement:2 cm) had RPN Dissection if residuals were suspected after PEBx3or4.
Results:
St.I: 26 patients. 3/26 had a scrotal approach due to suspected testicular torsion: 1/3 underwent hemiscrotectomy, 2 did not receive further therapy after decrease of alphaFP, due to patientâs or physicianâs decision respectively. 3/26 were successfully treated for RPN relapse, occurred at 3,6,9 months after adequate surgery (2 adolescents, 1 infant). St.II: in 4 patients CTwas delivered due to slight enlargement of RPN (+persistent alphaFP in 1). St.III: 12 patients received CT and RPND (bilateral in 1). Histology was negative in 11/12. All patients are alive without disease, 39 in 1stCR, 3 in 2ndCR (f.u 9â86 m.:med.48). 1 St.1 patient suffered from postoperative scrotal hematoma. Among patients younger than 2 y, 10/14 had a pure YST, 12/14 had St.I disease; among those between 13â18 y, 27/28 had a mixed histology, 14/28 were St.II or St.III. In 3 adolescents a testicular prosthesis was positioned during primary operation.
Conclusion:
Outcome was excellent. Regional relapses, observed only in St.I patients, were cured. Surgical guidelines were followed in 40/42 cases. Scrotal approach did not worsen the outcome of patients who did not receive further treatment
- âŠ