1,672 research outputs found
TDCOSMO XIV: Practical Techniques for Estimating External Convergence of Strong Gravitational Lens Systems and Applications to the SDSS J0924+0219 System
Time-delay cosmography uses strong gravitational lensing of a time-variable
source to infer the Hubble Constant. The measurement is independent from both
traditional distance ladder and CMB measurements. An accurate measurement with
this technique requires considering the effects of objects along the line of
sight outside the primary lens, which is quantified by the external convergence
(). In absence of such corrections, will be biased
towards higher values in overdense fields and lower values in underdense
fields. We discuss the current state of the methods used to account for
environment effects. We present a new software package built for this kind of
analysis and others that can leverage large astronomical survey datasets. We
apply these techniques to the SDSS J0924+0219 strong lens field. We infer the
relative density of the SDSS J0924+0219 field by computing weighted number
counts for all galaxies in the field, and comparing to weighted number counts
computed for a large number of fields in a reference survey. We then compute
weighted number counts in the Millennium Simulation and compare these results
to infer the external convergence of the lens field.Results. Our results show
the SDSS J0924+0219 field is a fairly typical line of sight, with median
and standard deviation .Comment: Submitted to A&A. 10 pages, 5 figure
The Hubble Constant determined through an inverse distance ladder including quasar time delays and Type Ia supernovae
Context. The precise determination of the present-day expansion rate of the
Universe, expressed through the Hubble constant , is one of the most
pressing challenges in modern cosmology. Assuming flat CDM,
inference at high redshift using cosmic-microwave-background data from Planck
disagrees at the 4.4 level with measurements based on the local
distance ladder made up of parallaxes, Cepheids and Type Ia supernovae (SNe
Ia), often referred to as "Hubble tension". Independent,
cosmological-model-insensitive ways to infer are of critical importance.
Aims. We apply an inverse-distance-ladder approach, combining strong-lensing
time-delay-distance measurements with SN Ia data. By themselves, SNe Ia are
merely good relative distance indicators, but by anchoring them to strong
gravitational lenses one can obtain an measurement that is relatively
insensitive to other cosmological parameters. Methods. A cosmological parameter
estimate is performed for different cosmological background models, both for
strong-lensing data alone and for the combined lensing + SNe Ia data sets.
Results. The cosmological-model dependence of strong-lensing measurements
is significantly mitigated through the inverse distance ladder. In combination
with SN Ia data, the inferred consistently lies around 73-74 km s
Mpc, regardless of the assumed cosmological background model. Our
results agree nicely with those from the local distance ladder, but there is a
>2 tension with Planck results, and a ~1.5 discrepancy with
results from an inverse distance ladder including Planck, Baryon Acoustic
Oscillations and SNe Ia. Future strong-lensing distance measurements will
reduce the uncertainties in from our inverse distance ladder.Comment: 5 pages, 3 figures, A&A letters accepted versio
Sparse 3D Point-cloud Map Upsampling and Noise Removal as a vSLAM Post-processing Step: Experimental Evaluation
The monocular vision-based simultaneous localization and mapping (vSLAM) is
one of the most challenging problem in mobile robotics and computer vision. In
this work we study the post-processing techniques applied to sparse 3D
point-cloud maps, obtained by feature-based vSLAM algorithms. Map
post-processing is split into 2 major steps: 1) noise and outlier removal and
2) upsampling. We evaluate different combinations of known algorithms for
outlier removing and upsampling on datasets of real indoor and outdoor
environments and identify the most promising combination. We further use it to
convert a point-cloud map, obtained by the real UAV performing indoor flight to
3D voxel grid (octo-map) potentially suitable for path planning.Comment: 10 pages, 4 figures, camera-ready version of paper for "The 3rd
International Conference on Interactive Collaborative Robotics (ICR 2018)
The impact of an educational program in the management of patients with chronic hepatitis C
Introduction: This study was designed to measure the impact of lifestyle changes, involving a diet therapy and physical exercises in patients with chronic hepatitis C (CHC). Methods: The study was conducted during January 2008 - December 2009 at âProf. N. Paulescuâ National Institute of Diabetes, Nutrition and Metabolic Diseases - Bucharest, Romania. We selected 67 patients (34 men/33 women). We performed anthropometric measurements (weight, height, BMI (body mass index), bioimpedance analysis (BIA) as well as fasting serum lipids (cholesterol, triglycerides, HDL-cholesterol), glucose profile (glucose, HbA1c), liver profile (ALT, AST, GGT, alkaline phosphatase, bilirubin, albumin, total protein), blood count for all patients at baseline. Results: The average age was 53.91±10.19 years. Obesity was present in 32.8% (n=22) of patients at baseline. Total fat mass decreased with weight loss 2.21 kg (p = 0.0001) respectively 3.17 kg (p = 0.0001). Weight loss was accompanied by decreased resting energy expenditure. Triglycerides decreased from 158.11±7.63 mg/dl to 134.88±6.1 mg/dl, cholesterol decreased from 187.3±6.8 mg/dl to 168.65±4.42 mg/dl and HDL-cholesterol increased from 45.13±1.9 mg/dl to 47.2±1.39 mg/dl after 12 months. Aspartaminotransferase, alaninaminotransferese, gamma-glutamil transpeptidase decreased with significant differences. Conclusions: Patients with hepatitis C undergoing an 1-year lifestyle intervention had significant improvements in fasting glucose, fasting insulin, HOMA-IR, lipidic profile, hepatic profile and adipose tissue distribution. The present study establishes the positive impact of an educational program in the management of patients with hepatitis C
H0LiCOW III. Quantifying the effect of mass along the line of sight to the gravitational lens HE 0435-1223 through weighted galaxy counts
Based on spectroscopy and multiband wide-field observations of the
gravitationally lensed quasar HE 0435-1223, we determine the probability
distribution function of the external convergence for
this system. We measure the under/overdensity of the line of sight towards the
lens system and compare it to the average line of sight throughout the
universe, determined by using the CFHTLenS as a control field. Aiming to
constrain as tightly as possible, we determine
under/overdensities using various combinations of relevant informative weighing
schemes for the galaxy counts, such as projected distance to the lens,
redshift, and stellar mass. We then convert the measured under/overdensities
into a distribution, using ray-tracing through the
Millennium Simulation. We explore several limiting magnitudes and apertures,
and account for systematic and statistical uncertainties relevant to the
quality of the observational data, which we further test through simulations.
Our most robust estimate of has a median value
and a standard deviation of
. The measured corresponds to
uncertainty on the time delay distance, and hence the Hubble constant
inference from this system. The median value
is robust to (i.e. on ) regardless of the adopted
aperture radius, limiting magnitude and weighting scheme, as long as the latter
incorporates galaxy number counts, the projected distance to the main lens, and
a prior on the external shear obtained from mass modeling. The availability of
a well-constrained makes \hequad\ a valuable system for
measuring cosmological parameters using strong gravitational lens time delays.Comment: 24 pages, 17 figures, 6 tables. Submitted to MNRA
Statin therapy in patients with diabetes and hepatitis C
The objective of this study was to determine the effects of statin therapy (atorvastatin) on serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in patients with type 2 diabetes mellitus (T2DM) and chronic hepatitis C (CHC). A number of 77 patients with T2DM and CHC were selected, treated with atorvastatin, 20 mg, for 6 months, who underwent anthropometric measurements and biochemical tests (including fasting serum glucose, lipid profile, liver profile, cytokines profile) at baseline, after 1 month (clinical and biochemical profile for safety) and after 6 months of treatment. The patientsâ average age was 52.53±9.7 years. Plasma low-density lipoprotein cholesterol (LDL-C) (-32.4 mg/dL), triglycerides (-29.7 mg/dL), total cholesterol (-32.8 mg/dL) decreased (p<0.05), and high-density lipoprotein cholesterol (HDL-C) (+3.04 mg/dL) increased (p<0.05), after 6 months. Atorvastatin treatment was associated with decreases of AST, ALT, and also leptin and interleukin-6 (IL-6) levels (all p<0.05) but we did not find any effect on plasma tumor necrosis factor-alpha (TNF-α) (p=0.119). Atorvastatin was an effective and well tolerated treatment for lowering total cholesterol, LDL-C, triglycerides in patients with CHC. Among patients with CHC there was no significant elevation of liver enzymes during statin treatment, and we even noticed an improvement of hepatic profile
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