186 research outputs found
Le 11 septembre 1942 : Les cheminots et les déportés juifs en gare de Fives-Lille
Paris le 20 septembre 2018Le témoignage qui suit est basé sur les récits de nos parents, Tauba Mandelbaum née Weissblum et Lejbus (Léon) Mandelbaum, concernant la journée du 11 septembre 1942. Cette journée s’inscrit dans notre histoire familiale comme une pierre à deux faces, l’une noire, l’autre blanche. Le 11 septembre 1942, jour de Rosh Hashana, nos parents sont réveillés, vers 5h30 du matin, par des coups frappés à la porte de leur maison, 6 rue du Marais à Lens. Un gendarme français et..
Dark Energy and Modified Gravity
Despite two decades of tremendous experimental and theoretical progress, the
riddle of the accelerated expansion of the Universe remains to be solved. On
the experimental side, our understanding of the possibilities and limitations
of the major dark energy probes has evolved; here we summarize the major probes
and their crucial challenges. On the theoretical side, the taxonomy of
explanations for the accelerated expansion rate is better understood, providing
clear guidance to the relevant observables. We argue that: i) improving
statistical precision and systematic control by taking more data, supporting
research efforts to address crucial challenges for each probe, using
complementary methods, and relying on cross-correlations is well motivated; ii)
blinding of analyses is difficult but ever more important; iii) studies of dark
energy and modified gravity are related; and iv) it is crucial that R&D for a
vibrant dark energy program in the 2030s be started now by supporting studies
and technical R&D that will allow embryonic proposals to mature. Understanding
dark energy, arguably the biggest unsolved mystery in both fundamental particle
physics and cosmology, will remain one of the focal points of cosmology in the
forthcoming decade.Comment: 5 pages + references; science white paper submitted to the Astro2020
decadal surve
Single-object Imaging and Spectroscopy to Enhance Dark Energy Science from LSST
Single-object imaging and spectroscopy on telescopes with apertures ranging
from ~4 m to 40 m have the potential to greatly enhance the cosmological
constraints that can be obtained from LSST. Two major cosmological probes will
benefit greatly from LSST follow-up: accurate spectrophotometry for nearby and
distant Type Ia supernovae will expand the cosmological distance lever arm by
unlocking the constraining power of high-z supernovae; and cosmology with time
delays of strongly-lensed supernovae and quasars will require additional
high-cadence imaging to supplement LSST, adaptive optics imaging or
spectroscopy for accurate lens and source positions, and IFU or slit
spectroscopy to measure detailed properties of lens systems. We highlight the
scientific impact of these two science drivers, and discuss how additional
resources will benefit them. For both science cases, LSST will deliver a large
sample of objects over both the wide and deep fields in the LSST survey, but
additional data to characterize both individual systems and overall systematics
will be key to ensuring robust cosmological inference to high redshifts.
Community access to large amounts of natural-seeing imaging on ~2-4 m
telescopes, adaptive optics imaging and spectroscopy on 8-40 m telescopes, and
high-throughput single-target spectroscopy on 4-40 m telescopes will be
necessary for LSST time domain cosmology to reach its full potential. In two
companion white papers we present the additional gains for LSST cosmology that
will come from deep and from wide-field multi-object spectroscopy.Comment: Submitted to the call for Astro2020 science white paper
Empirical relationships among oliguria, creatinine, mortality, and renal replacement therapy in the critically ill
Purpose: The observation periods and thresholds of serum creatinine and urine output defined in the Acute Kidney Injury Network (AKIN) criteria were not empirically derived. By continuously varying creatinine/urine output thresholds as well as the observation period, we sought to investigate the empirical relationships among creatinine, oliguria, in-hospital mortality, and receipt of renal replacement therapy (RRT).
Methods: Using a high-resolution database (Multiparameter Intelligent Monitoring in Intensive Care II), we extracted data from 17,227 critically ill patients with an in-hospital mortality rate of 10.9 %. The 14,526 patients had urine output measurements. Various combinations of creatinine/urine output thresholds and observation periods were investigated by building multivariate logistic regression models for in-hospital mortality and RRT predictions. For creatinine, both absolute and percentage increases were analyzed. To visualize the dependence of adjusted mortality and RRT rate on creatinine, the urine output, and the observation period, we generated contour plots.
Results: Mortality risk was high when absolute creatinine increase was high regardless of the observation period, when percentage creatinine increase was high and the observation period was long, and when oliguria was sustained for a long period of time. Similar contour patterns emerged for RRT. The variability in predictive accuracy was small across different combinations of thresholds and observation periods.
Conclusions: The contour plots presented in this article complement the AKIN definition. A multi-center study should confirm the universal validity of the results presented in this articleNational Institute of Biomedical Imaging and Bioengineering (U.S.) (Grant R01 EB001659
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Evolution and Current Role of Autologous Chondrocyte Implantation for Treatment of Articular Cartilage Defects in the Football (Soccer) Player
Background: Autologous chondrocyte implantation (ACI) continues to technically evolve, but how the technical innovations affect the ability to participate in high-impact sports such as football is unknown. Methods: Clinical studies describing athletes treated with first-, second-, or third-generation ACI techniques were reviewed. The technical developments of ACI were evaluated, and the results in athletes and specifically football (soccer) players were analyzed. Results: Football players reported 72% good to excellent results with significant overall improvement of knee function and activity scores. Return to football was 83% in competitive players but lower in recreational players. Eighty percent of players returned to the same competitive level after ACI, and 87% to 100% maintained their ability to play sports at 5 years postoperatively. Return to sport was better for younger, competitive players with shorter intervals between injury and ACI. New developments of the surgical technique and postoperative rehabilitation were able to reduce the limitations associated with first-generation ACI including invasiveness, graft hypertrophy, and particularly long postoperative rehabilitation. This allowed for faster return to sports like football without compromising the ability for continued competition over time. Conclusion: Articular cartilage repair in football players often allows for successful return to this high-impact sport with excellent durability. The continued evolution of this technique has improved initial shortcomings with important implications for both the professional and recreational athlete
Wide-field Multi-object Spectroscopy to Enhance Dark Energy Science from LSST
LSST will open new vistas for cosmology in the next decade, but it cannot
reach its full potential without data from other telescopes. Cosmological
constraints can be greatly enhanced using wide-field ( deg total
survey area), highly-multiplexed optical and near-infrared multi-object
spectroscopy (MOS) on 4-15m telescopes. This could come in the form of
suitably-designed large surveys and/or community access to add new targets to
existing projects. First, photometric redshifts can be calibrated with high
precision using cross-correlations of photometric samples against spectroscopic
samples at that span thousands of sq. deg. Cross-correlations of
faint LSST objects and lensing maps with these spectroscopic samples can also
improve weak lensing cosmology by constraining intrinsic alignment systematics,
and will also provide new tests of modified gravity theories. Large samples of
LSST strong lens systems and supernovae can be studied most efficiently by
piggybacking on spectroscopic surveys covering as much of the LSST
extragalactic footprint as possible (up to square degrees).
Finally, redshifts can be measured efficiently for a high fraction of the
supernovae in the LSST Deep Drilling Fields (DDFs) by targeting their hosts
with wide-field spectrographs. Targeting distant galaxies, supernovae, and
strong lens systems over wide areas in extended surveys with (e.g.) DESI or MSE
in the northern portion of the LSST footprint or 4MOST in the south could
realize many of these gains; DESI, 4MOST, Subaru/PFS, or MSE would all be
well-suited for DDF surveys. The most efficient solution would be a new
wide-field, highly-multiplexed spectroscopic instrument in the southern
hemisphere with m aperture. In two companion white papers we present gains
from deep, small-area MOS and from single-target imaging and spectroscopy.Comment: Submitted to the call for Astro2020 science white papers; tables with
estimates of telescope time needed for a supernova host survey can be seen at
http://d-scholarship.pitt.edu/id/eprint/3604
Disentangling dark energy and cosmic tests of gravity from weak lensing systematics
We consider the impact of key astrophysical and measurement systematics on
constraints on dark energy and modifications to gravity on cosmic scales. We
focus on upcoming photometric "Stage III" and "Stage IV" large scale structure
surveys such as DES, SuMIRe, Euclid, LSST and WFIRST. We illustrate the
different redshift dependencies of gravity modifications compared to intrinsic
alignments, the main astrophysical systematic. The way in which systematic
uncertainties, such as galaxy bias and intrinsic alignments, are modelled can
change dark energy equation of state and modified gravity figures of merit by a
factor of four. The inclusion of cross-correlations of cosmic shear and galaxy
position measurements helps reduce the loss of constraining power from the
lensing shear surveys. When forecasts for Planck CMB and Stage IV surveys are
combined, constraints on the dark energy equation of state and modified gravity
model are recovered, relative to those from shear data with no systematic
uncertainties, if fewer than 36 free parameters in total are used to describe
the galaxy bias and intrinsic alignment models as a function of scale and
redshift. To facilitate future investigations, we also provide a fitting
function for the matter power spectrum arising from the phenomenological
modified gravity model we consider.Comment: 18 pages, 8 figure
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The LSST DESC data challenge 1: Generation and analysis of synthetic images for next-generation surveys
Data Challenge 1 (DC1) is the first synthetic data set produced by the Rubin Observatory Legacy Survey of Space and Time (LSST) Dark Energy Science Collaboration (DESC). DC1 is designed to develop and validate data reduction and analysis and to study the impact of systematic effects that will affect the LSST data set. DC1 is comprised of r-band observations of 40 deg2 to 10 yr LSST depth. We present each stage of the simulation and analysis process: (a) generation, by synthesizing sources from cosmological N-body simulations in individual sensor-visit images with different observing conditions; (b) reduction using a development version of the LSST Science Pipelines; and (c) matching to the input cosmological catalogue for validation and testing. We verify that testable LSST requirements pass within the fidelity of DC1. We establish a selection procedure that produces a sufficiently clean extragalactic sample for clustering analyses and we discuss residual sample contamination, including contributions from inefficiency in star-galaxy separation and imperfect deblending. We compute the galaxy power spectrum on the simulated field and conclude that: (i) survey properties have an impact of 50 per cent of the statistical uncertainty for the scales and models used in DC1; (ii) a selection to eliminate artefacts in the catalogues is necessary to avoid biases in the measured clustering; and (iii) the presence of bright objects has a significant impact (2-6) in the estimated power spectra at small scales (> 1200), highlighting the impact of blending in studies at small angular scales in LSST
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