107 research outputs found
Gravitational lensing and dynamics in SL2S\,J02140-0535: Probing the mass out to large radius
We aim to probe the mass of SL2S\,J02140-0535, a galaxy group at = 0.44
from the Strong Lensing Legacy Survey (SL2S). We combine strong lensing
modeling and dynamical constraints. The strong lensing analysis is based on
multi-band HST/ACS observations exhibiting strong lensing features that we have
followed-up spectroscopically with VLT/FORS2. To constrain the scale radius of
an NFW mass profile that cannot be constrained by strong lensing, we propose a
new method by taking advantage of the large-scale dynamical information
provided by VLT/FORS2 and KECK/LRIS spectroscopy of group members. In constrast
to other authors, we show that the observed lensing features in
SL2S\,J02140-0535 belong to different background sources: one at = 1.7
0.1 produces three images, while the other at = 1.023 0.001 has
only a single image. Our unimodal NFW mass model reproduces these images very
well. It is characterized by a concentration parameter = 6.0
0.6, which is slightly greater than the value expected from CDM
simulations for a mass of M 1 10 M_{\sun}.
The spectroscopic analysis of group members also reveals a unimodal structure
that exhibits no evidence of merging. We compare our dynamic mass estimate with
an independent weak-lensing based mass estimate finding that both are
consistent. Our combined lensing and dynamical analysis of SL2S\,J02140-0535
demonstrates the importance of spectroscopic information in reliably
identifying the lensing features. Our findings argue that the system is a
relaxed, massive galaxy group where mass is traced by light. This work shows a
potentially useful method for constraining large-scale properties inaccessible
to strong lensing, such as the scale radius of the NFW profile.Comment: Accepted for publication in A&
The Decline of the Non-Hispanic White Population in the United States of America
Objectives: The question of a declining non-Hispanic white (NHW) population has sparked debate in the United States. In examining this question, three bodies of research have emerged. One group reports that the decline is real, a second argues that it is an illusion, and the third provides evidence that the decline is concentrated within socio-economic segments of the NHW population. We use the third groupsâ insight as the starting point for our research objective. Methods: In conjunction with data from Census Bureau sources, we use a series of Regression Models in this inquiry. Results: Our results show that the decline of the NHW population is real and related to factors embedded in the institutional anomie theory (IAT) framework. Conclusions: We conclude that the IAT framework is a suitable approach for examining the question of NHW population decline. However, we suggest that future research consider refining our approach by: (1) using sub-state areas as the units of analyses; (2) examining changes in the NHW population relative to lagged changes in the IAT framework at both the state and sub-state levels; (3) placing our framework into an âalgorithmic modeling approachâ that employs machine learning; and (4) developing anomie predictors
School quality, safe schools: an emperical analysis
While the vast majority of US public schools are safe, problems exist that not only threaten the teaching and learning environment, but cause substantive problems for educators. Sensing that certain troubling student behaviors can lead to greater problems, schools have implemented many safe school programs and strategies. Unfortunately, these approaches are viewed as "add-ons" by the education community; that is, additional activities and work for them. What is needed is a framework where safe school programs and strategies are fully integrated into the schooling process. Such a framework exists, and the purpose of our paper has been to integrate the safe schools literature with the quality schools literature in developing such a framework.
After reviewing the school quality and school safety literature we extracted main concepts from both bodies of research, and led to an overriding proposition. The proposition suggests that safe school activities can be successful if they are part of the larger task of developing and sustaining quality schools.
An analysis of school quality and safety data collected by the NEA tentatively confirms our main proposition. We found that school quality is significantly related to school safety. Additional findings suggest that safety varies across schools, middle schools have more problems than either elementary or high schools, and that the effect of school quality on safety does not depend on grade level. Taken as a whole, the effect of school quality on school safety appears to be very robus
Strong lensing, weak lensing, and dynamics in SL2S J02140-0535
International audienceWe combine strong lensing modeling and dynamical constraints in order to probe the mass of SL2S J02140-0535, a galaxy group at z = 0.44 from the Strong Lensing Legacy Survey (SL2S) which has uncovered a new population of group-scale strong lenses. The strong lensing analysis is based on multi-band HST/ACS observations which display strong lensing features that we have followed up spectroscopically with VLT/FORS2. To constrain the scale radius of an NFW mass profile, we propose a new method taking advantage of the large scale dynamical information provided by VLT/FORS2 and KECK/LRIS spectroscopy of group members. This work shows a potentially useful method for constraining large-scale properties inaccessible to strong lensing, such as the scale radius of the NFW profile
A New Window of Exploration in the Mass Spectrum: Strong Lensing by Galaxy Groups in the SL2S
The existence of strong lensing systems with Einstein radii (Re) covering the
full mass spectrum, from ~1-2" (produced by galaxy scale dark matter haloes) to
>10" (produced by galaxy cluster scale haloes) have long been predicted. Many
lenses with Re around 1-2" and above 10" have been reported but very few in
between. In this article, we present a sample of 13 strong lensing systems with
Re in the range 3"- 8", i.e. systems produced by galaxy group scale dark matter
haloes, spanning a redshift range from 0.3 to 0.8. This opens a new window of
exploration in the mass spectrum, around 10^{13}- 10^{14} M_{sun}, which is a
crucial range for understanding the transition between galaxies and galaxy
clusters. Our analysis is based on multi-colour CFHTLS images complemented with
HST imaging and ground based spectroscopy. Large scale properties are derived
from both the light distribution of the elliptical galaxies group members and
weak lensing of the faint background galaxy population. On small scales, the
strong lensing analysis yields Einstein radii between 2.5" and 8". On larger
scales, the strong lenses coincide with the peak of the light distribution,
suggesting that mass is traced by light. Most of the luminosity maps have
complicated shapes, indicating that these intermediate mass structures are
dynamically young. Fitting the reduced shear with a Singular Isothermal Sphere,
we find sigma ~ 500 km/s and an upper limit of ~900 km/s for the whole sample.
The mass to light ratio for the sample is found to be M/L_i ~ 250 (solar units,
corrected for evolution), with an upper limit of 500. This can be compared to
mass to light ratios of small groups (with sigma ~ 300 km/s and galaxy clusters
with sigma > 1000 km/s, thus bridging the gap between these mass scales.Comment: A&A Accepted. Draft with Appendix images can be found at
http://www.dark-cosmology.dk/~marceau/groups_sl2s.pd
Pion and proton showers in the CALICE scintillator-steel analogue hadron calorimeter
Showers produced by positive hadrons in the highly granular CALICE
scintillator-steel analogue hadron calorimeter were studied. The experimental
data were collected at CERN and FNAL for single particles with initial momenta
from 10 to 80 GeV/c. The calorimeter response and resolution and spatial
characteristics of shower development for proton- and pion-induced showers for
test beam data and simulations using Geant4 version 9.6 are compared.Comment: 26 pages, 16 figures, JINST style, changes in the author list, typos
corrected, new section added, figures regrouped. Accepted for publication in
JINS
Hadron shower decomposition in the highly granular CALICE analogue hadron calorimeter
The spatial development of hadronic showers in the CALICE scintillator-steel
analogue hadron calorimeter is studied using test beam data collected at CERN
and FNAL for single positive pions and protons with initial momenta in the
range from 10 to 80 GeV/c. Both longitudinal and radial development of hadron
showers are parametrised with two-component functions. The parametrisation is
fit to test beam data and simulations using the QGSP_BERT and FTFP_BERT physics
lists from Geant4 version 9.6. The parameters extracted from data and simulated
samples are compared for the two types of hadrons. The response to pions and
the ratio of the non-electromagnetic to the electromagnetic calorimeter
response, h/e, are estimated using the extrapolation and decomposition of the
longitudinal profiles.Comment: 38 pages, 19 figures, 5 tables; author list changed; submitted to
JINS
Shower development of particles with momenta from 15 GeV to 150 GeV in the CALICE scintillator-tungsten hadronic calorimeter
We present a study of showers initiated by electrons, pions, kaons, and
protons with momenta from 15 GeV to 150 GeV in the highly granular CALICE
scintillator-tungsten analogue hadronic calorimeter. The data were recorded at
the CERN Super Proton Synchrotron in 2011. The analysis includes measurements
of the calorimeter response to each particle type as well as measurements of
the energy resolution and studies of the longitudinal and radial shower
development for selected particles. The results are compared to Geant4
simulations (version 9.6.p02). In the study of the energy resolution we include
previously published data with beam momenta from 1 GeV to 10 GeV recorded at
the CERN Proton Synchrotron in 2010.Comment: 35 pages, 21 figures, 8 table
Utility of positron emission tomography-computed tomography in patients with chronic lymphocytic leukemia following B-cell receptor pathway inhibitor therapy
The utility of positron emission tomography-computed tomography (PET-CT) in distinguishing Richterâs transformation versus chronic lymphocytic leukemia (CLL) progression after ibrutinib and/or idelalisib was assessed in a post hoc analysis of a phase II study of venetoclax. Patients underwent PET-CT at screening and were not enrolled/treated if Richterâs transformation was confirmed pathologically. Of 167 patients screened, 57 met criteria for biopsy after PET-CT. Of 35 patients who underwent biopsy, eight had Richterâs transformation, two had another malignancy, and 25 had CLL. A PET-CT maximum standardized uptake value (SUVmax) â„10 had 71% sensitivity and 50% specificity for detecting Richterâs transformation [Odds Ratio (OR): 2.5, 95%CI: 0.4-15; P=0.318]. Response rate to venetoclax was similar for screening SUVma
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