31 research outputs found
Towards three-dimensional underwater mapping without odometry
This paper presents a method for the creation of three-dimensional maps of underwater cisterns and wells using a submersible robot equipped with two scanning sonars and a compass. Previous work in this area utilized a particle filter to perform offline simultaneous localization and mapping (SLAM) in two dimensions using a single sonar [11]. This work utilizes scan matching and incorporates an additional sonar that scans in a perpendicular plane. Given a set of overlapping horizontal and vertical sonar scans, an algorithm was implemented to map underwater chambers by matching sets of scans using a weighted iterative closest point (ICP) method. This matching process has been augmented to align the features of the underwater cistern data without robot odometry. Results from a swimming pool and an archeological site trials indicate successful mapping is achieved
The mass profile of early-type galaxies in overdense environments: the case of the double source plane gravitational lens SL2SJ02176-0513
SL2SJ02176-0513 is a remarkable lens for the presence of two multiply-imaged
systems at different redshifts lensed by a foreground massive galaxy at : a bright cusp arc at and an additional
double-image system at an estimated redshift of based on
photometry and lensing geometry. The system is located about 400 kpc away from
the center of a massive group of galaxies. Mass estimates for the group are
available from X-ray observations and satellite kinematics. Multicolor
photometry provides an estimate of the stellar mass of the main lens galaxy.
The lensing galaxy is modeled with two components (stars and dark matter), and
we include the perturbing effect of the group environment, and all available
constraints. We find that classic lensing degeneracies, e.g. between external
convergence and mass density slope, are significantly reduced with respect to
standard systems and infer tight constraints on the mass density profile: (i)
the dark matter content of the main lens galaxy is in line with that of typical
galaxies ; (ii) the required mass
associated with the dark matter halo of the nearby group is consistent with
X-ray and weak-lensing estimates (); (iii)
accounting for the group contribution in the form of an external convergence,
the slope of the mass density profile of the main lens galaxy alone is found to
be , consistent with the isothermal ()
slope. We demonstrate that multiple source plane systems together with good
ancillary dataset can be used to disentangle local and environmental effects.Comment: 10 pages, 6 figures, submitted to A&
On the evolution of environmental and mass properties of strong lens galaxies in COSMOS
Among the 100 strong lens candidates found in the COSMOS field, 20 with
redshifts in the range [0.34,1.13], feature multiple images of background
sources. Using the multi-wavelength coverage of the field and its spectroscopic
follow-up, we characterize the evolution with redshift of the environment and
of the dark-matter (DM) fraction of the lens galaxies. We present new redshift
of the strong lens candidates. The lens environment is characterized by the
projected 10 closest galaxies around each lens and by the number of galaxies
with a projected distance less than 1Mpc at the lens galaxy redshift. In both
cases, we perform similar measurements on a control sample of twin non-lens
early type galaxies (ETGs). In addition, we identify group members and field
galaxies in the X-ray and optical catalogs of galaxy groups. From those
catalogs, we measure the external shear contribution at the lens galaxy
positions. The systems are then modeled using a SIE plus the external shear due
to the groups. We observe that the average stellar mass of lens galaxies
increases with z and that the environment of lens galaxies is compatible with
that of the twins. During the lens modeling, we notice that, when let free, the
external shear points in a direction which is the mean direction of the
external shear due to groups and of the closest galaxy to the lens. We notice
that the DM fraction of the lens galaxies within the Einstein radius decreases
as the redshift increases. Given these, we conclude that, while the environment
of lens galaxies is compatible with that of non-lens ETGS, their mass
properties evolves significantly with redshift: it is still not clear whether
this advocates in favor of a stronger lensing bias toward massive objects at
high redshift or is simply representative of the high proportion of massive and
high stellar density galaxies at high redshift.Comment: Accepted for publication in A&A. Significant modifications in the
paper but similar conclusion
The mass distribution of a moderate redshift galaxy group and brightest group galaxy from gravitational lensing and kinematics
The gravitational lens system CLASS B2108+213 has two radio-loud lensed
images separated by 4.56 arcsec. The relatively large image separation implies
that the lensing is caused by a group of galaxies. In this paper, new optical
imaging and spectroscopic data for the lensing galaxies of B2108+213 and the
surrounding field galaxies are presented. These data are used to investigate
the mass and composition of the lensing structure. The redshift and stellar
velocity dispersion of the main lensing galaxy (G1) are found to be z = 0.3648
+/- 0.0002 and sigma_v = 325 +/- 25 km/s, respectively. The optical spectrum of
the lensed quasar shows no obvious emission or absorption features and is
consistent with a BL Lac type radio source. However, the tentative detection of
the G-band and Mg-b absorption lines, and a break in the spectrum of the host
galaxy of the lensed quasar gives a likely source redshift of z = 0.67.
Spectroscopy of the field around B2108+213 finds 51 galaxies at a similar
redshift to G1, thus confirming that there is a much larger structure at z ~
0.365 associated with this system. The width of the group velocity distribution
is 694 +/- 93 km/s, but is non-Gaussian, implying that the structure is not yet
viralized. The main lensing galaxy is also the brightest group member and has a
surface brightness profile consistent with a typical cD galaxy. A lensing and
dynamics analysis of the mass distribution, which also includes the newly found
group members, finds that the logarithmic slope of the mass density profile is
on average isothermal inside the Einstein radius, but steeper at the location
of the Einstein radius. This apparent change in slope can be accounted for if
an external convergence gradient, representing the underlying parent halo of
the galaxy group, is included in the mass model.Comment: 18 pages, 14 figures, 5 tables, accepted for publication in MNRA
The Hubble Constant
I review the current state of determinations of the Hubble constant, which
gives the length scale of the Universe by relating the expansion velocity of
objects to their distance. There are two broad categories of measurements. The
first uses individual astrophysical objects which have some property that
allows their intrinsic luminosity or size to be determined, or allows the
determination of their distance by geometric means. The second category
comprises the use of all-sky cosmic microwave background, or correlations
between large samples of galaxies, to determine information about the geometry
of the Universe and hence the Hubble constant, typically in a combination with
other cosmological parameters. Many, but not all, object-based measurements
give values of around 72-74km/s/Mpc , with typical errors of 2-3km/s/Mpc.
This is in mild discrepancy with CMB-based measurements, in particular those
from the Planck satellite, which give values of 67-68km/s/Mpc and typical
errors of 1-2km/s/Mpc. The size of the remaining systematics indicate that
accuracy rather than precision is the remaining problem in a good determination
of the Hubble constant. Whether a discrepancy exists, and whether new physics
is needed to resolve it, depends on details of the systematics of the
object-based methods, and also on the assumptions about other cosmological
parameters and which datasets are combined in the case of the all-sky methods.Comment: Extensively revised and updated since the 2007 version: accepted by
Living Reviews in Relativity as a major (2014) update of LRR 10, 4, 200
Serratus anterior plane versus paravertebral nerve blocks for postoperative analgesia after non-mastectomy breast surgery: a randomized controlled non-inferiority trial
BackgroundParavertebral and serratus plane blocks are both used to treat pain following breast surgery. However, it remains unknown if the newer serratus block provides comparable analgesia to the decades-old paravertebral technique.MethodsSubjects undergoing unilateral or bilateral non-mastectomy breast surgery were randomized to a single-injection serratus or paravertebral block in a subject-masked fashion (ropivacaine 0.5%; 20 mL unilateral; 16 mL/side bilateral). We hypothesized that (1) analgesia would be non-inferior in the recovery room with serratus blocks (measurement: Numeric Rating Scale), and (2) opioid consumption would be non-inferior with serratus blocks in the operating and recovery rooms. In order to claim that serratus blocks are non-inferior to paravertebral blocks, both hypotheses must be at least non-inferior.ResultsWithin the recovery room, pain scores for participants with serratus blocks (n=49) had a median (IQR) of 4.0 (0-5.5) vs 0 (0-3.0) for those with paravertebral blocks (n=51): 0.95% CI -3.00 to -0.00; p=0.001. However, the difference in morphine equivalents did not reach statistical significance for superiority with the serratus group consuming 14 mg (10-19) vs 10 mg (10-16) for the paravertebral group: 95% CI -4.50 to 0.00, p=0.123. Since the 95% CI lower limit of -4.5 was less than our prespecified margin of -2.0, we failed to conclude non-inferiority of the serratus block with regard to opioid consumption.ConclusionsSerratus blocks provided inferior analgesia compared with paravertebral blocks. Without a dramatic improvement in safety profile for serratus blocks, it appears that paravertebral blocks are superior to serratus blocks for postoperative analgesia after non-mastectomy breast surgery.Trial registration numberNCT03860974
Recommended from our members
ExoFiT: ExoMars-Like Field Trials – a Mission Simulation.
International audienceHere, we focus on the ExoMars-Like Field Trial (ExoFiT), a series of realistic mission simulations based on the ESA ExoMars rover mission slated to be launched in 2020. The mission will carry a suite of instruments to carry out its mission objectives focused on geological and exobiological researc
Quando o silêncio é rompido: o processo de revelação e notificação de abuso sexual infantil When the silence is broken: the process of disclosure and reporting of child sexual abuse
O objetivo deste artigo é discutir o processo de revelação e notificação de situações de abuso sexual envolvendo crianças e adolescentes, a partir da análise de publicações relacionadas a essa temática. Os estudos indicam que a revelação e a notificação do abuso sexual são momentos difíceis para a vítima e para seus familiares porque geralmente envolvem alguém próximo à criança e apresentam reflexos no sistema familiar, como rompimento de vínculo, culpabilização e perda de suporte financeiro. Vários fatores que podem facilitar ou inibir a revelação e notificação do abuso são discutidos, como, por exemplo, a reação materna. Destaca-se a importância de um trabalho integrado no atendimento às vítimas, no encaminhamento das questões judiciais e no fortalecimento da rede de apoio às famílias.<br>The aim of this article is to discuss the process of disclosure and reporting of cases of sexual abuse involving children and adolescents, based on the analysis of publications related to that topic. Studies suggest that the disclosure and reporting of sexual abuse is a difficult moment for the victims and their families because it usually involves someone close to the child. It provokes changes in the family system, such as disruption of ties, guilt and loss in financial support. Several factors that may facilitate or inhibit the disclosure and reporting of sexual abuse are discussed such as the mother's reaction. It is highlighted the importance of an integrated work in the service that deals with these situations, involving the victims care, in the forwarding of the processes and in the strengthening of the supporting network for families