82 research outputs found
Broadband dual-comb hyperspectral imaging and adaptable spectroscopy with programmable frequency combs
We explore the advantages of a free-form dual-comb spectroscopy (DCS)
platform based on time-programmable frequency combs for real-time, penalty-free
apodized scanning. In traditional DCS, the fundamental spectral resolution,
which equals the comb repetition rate, can be excessively fine for many
applications. While the fine resolution is not itself problematic, it comes
with the penalty of excess acquisition time. Post-processing apodization
(windowing) can be applied to tailor the resolution to the sample, but only
with a deadtime penalty proportional to the degree of apodization. The excess
acquisition time remains. With free-form DCS, this deadtime is avoided by
programming a real-time apodization pattern that dynamically reverses the pulse
periods between the dual frequency combs. In this way, one can tailor the
spectrometer's resolution and update rate to different applications without
penalty. We show operation of a free-form DCS system where the spectral
resolution is varied from the intrinsic fine resolution of 160 MHz up to 822
GHz by applying tailored real-time apodization. Because there is no deadtime
penalty, the spectral signal-to-noise ratio increases linearly with resolution
by 5000x over this range, as opposed to the square root increase observed for
postprocessing apodization in traditional DCS. We explore the flexibility to
change resolution and update rate to perform hyperspectral imaging at slow
camera frame rates, where the penalty-free apodization allows for optimal use
of each frame. We obtain dual-comb hyperspectral movies at a 20 Hz spectrum
update rate with broad optical spectral coverage of over 10 THz
Enseigner des valeurs à l'ordre collégial
Dans le contexte social et scolaire actuel, il existe une volonté de plus en plus grande des cégeps de donner un sens à la formation technique en enseignant les valeurs rattachées au métier, tout en faisant de la réussite des études une entreprise personnelle. À cet égard, un partenariat entre le Cégep Limoilou et l’Université Laval a permis de développer des activités pédagogiques concrètes pour l’enseignement de valeurs entrepreneuriales dans la formation technique. Cet article présente Ça me tient à cœur !, une activité élaborée en vue de l’acquisition de valeurs entrepreneuriales dans une perspective de développement durable. On y expose les visées de l’activité, les modalités de son déroulement et les résultats de son expérimentation en classe. Réalisée dans un programme technique spécifique, à savoir le programme de Technologie de la mécanique du bâtiment, l’activité présentée est néanmoins transférable à tout programme collégial dont les buts recouvrent le développement de valeurs ou la formation citoyenne. L’article évoque enfin trois autres activités visant le développement d’un système de valeur par les étudiants
Separation of dust emission from the Cosmic Infrared Background in Herschel observations with Wavelet Phase Harmonics
The low brightness dust emission at high Galactic latitude is of interest to
study the interplay between physical processes in shaping the structure of the
interstellar medium (ISM), as well as to statistically characterize dust
emission as a foreground to the Cosmic Microwave Background (CMB). Progress in
this avenue of research have been hampered by the difficulty of separating the
dust emission from the Cosmic Infrared Background (CIB). We demonstrate that
dust and CIB may be effectively separated based on their different structure on
the sky and use the separation to characterize the structure of diffuse dust
emission on angular scales where CIB is a significant component in terms of
power. We use scattering transform statistics, the Wavelet Phase Harmonics
(WPH), to perform a statistical component separation using Herschel SPIRE
observations. This component separation is done only from observational data
using non-Gaussian properties as a lever arm, and is done at a single 250
microns frequency. This method, that we validate on mock data, gives us access
to non-Gaussian statistics of the interstellar dust and an output dust map
essentially free from CIB contamination. Our statistical modelling
characterizes the non-Gaussian structure of the diffuse ISM down to the
smallest scales observed by Herschel. We recover the power-law shape of the
dust power spectrum up to a wavenumber of 2 arcmin where the dust signal
represents 2 percent of the total power. The output dust map reveals coherent
structures at the smallest scales which were hidden by the CIB anisotropies. It
opens new observational perspectives on the formation of structure in the
diffuse ISM which we discuss with reference to past work. We have succeeded to
perform a statistical separation from observational data only at a single
frequency by using non-Gaussian statistics.Comment: Accepted in A&A on October 23, 202
Traduction et adaptation d’un modèle du jugement clinique infirmier pour la recherche et la formation infirmière en contexte francophone
Afin de guider le développement de la science et de la pratique de la formation infirmière, la diffusion de connaissances en français sur ce que signifie apprendre à penser comme une infirmière ou un infirmier et la manière de faciliter cet apprentissage demeure un enjeu important. Cet article présente la traduction, l’adaptation et la validation d’une version française du modèle du jugement clinique infirmier de Tanner (2006). Une démarche de traduction, rétrotraduction et validation en quatre étapes a été réalisée selon les recommandations de Sousa et Rojjanasrirat (2011). La version française du modèle a été validée par 10 expertes en formation infirmière et par son autrice originale. Le jugement clinique y est défini comme une compréhension, un constat ou une conclusion relative aux besoins, aux préoccupations ou aux problèmes de santé d’une personne. Le modèle décrit quatre aspects interreliés qui s’appliquent dans les situations de soins qui peuvent évoluer rapidement et dont les paramètres sont ambigus ou mal définis : remarquer, interpréter, répondre et réfléchir. En plus de décrire le jugement clinique d’infirmières et d’infirmiers de différents niveaux d’expertise, ce modèle est un outil important pour guider la recherche en formation infirmière et la création d’expériences d’apprentissage des soins infirmiers. Il s’agit aussi d’un outil pertinent en contexte d’évaluation et de mentorat.To pursue the development of the science and practice of nursing education, the dissemination of knowledge in French about learning to think like a nurse and how to facilitate this learning remains an important issue. This article presents the French translation, adaptation, and validation of Tanner's (2006) Model of Clinical Judgment in nursing. A four-step process of translation, back-translation, and validation was conducted according to the recommendations of Sousa and Rojjanasrirat (2011). The French version of the model was validated by 10 nursing education experts and by its original author. The model defines clinical judgment as an understanding, interpretation, or conclusion about a person's health needs, concerns, or problems. It describes four interrelated aspects of clinical judgment that can apply to rapidly changing care situations with ambiguous or ill-defined parameters: noticing, interpreting, responding, and reflecting. In addition to describing the clinical judgment of nurses with different levels of expertise, this model is an important tool to guide nursing education research and design educational experiences for nurses and nursing students. It is also a relevant tool for assessment and mentoring
Foreground Analysis Using Cross-Correlations of External Templates on the 7-year WMAP data
WMAP data when combined with ancillary data on free-free, synchrotron and
dust allow an improved understanding of the spectrum of emission from each of
these components. Here we examine the sky variation at intermediate and high
latitudes using a cross-correlation technique. In particular, we compare the
observed emission in several large partitions of the sky plus 33 selected sky
regions to three "standard" templates. The regions are selected using a
criterion based on the morphology of these template maps. The synchrotron
emission shows evidence of steepening between GHz frequencies and the
\emph{WMAP} bands. There are indications of spectral index variations across
the sky but the current data are not precise enough to accurately quantify this
from region-to-region. The emission correlated with the template
shows clear evidence of deviation from a free-free spectrum. The emission can
be decomposed into a contribution from both free-free and spinning dust in the
warm ionised medium of the Galaxy. The derived free-free emissivity corresponds
to a mean electron temperature of K, although the value depends
critically on the impact of dust absorption on the intensity. The
WIM spinning dust emission has a peak emission in intensity in the range 40--50
GHz. The anomalous microwave emission associated with dust is detected at high
significance in most of the 33 fields studied. The anomalous emission
correlates well with the Finkbeiner et al. (1999) model 8 predictions (FDS8) at
94 GHz, and is well described globally by a power-law emission model with an
effective spectral index between 20 and 60 GHz of . It is
clear that attempts to explain the emission by spinning dust models require
multiple components, which presumably relates to a complex mix of emission
regions along a given line-of-sight.Comment: 31 pages, 14 figure
A measurement of the millimetre emission and the Sunyaev-Zel'dovich effect associated with low-frequency radio sources
We present a statistical analysis of the millimetre-wavelength properties of 1.4GHz-selected sources and a detection of the Sunyaev–Zel’dovich (SZ) effect associated with the haloes that host them. We stack data at 148, 218 and 277GHz from the Atacama Cosmology Telescope at the positions of a large sample of radio AGN selected at 1.4GHz. The thermal SZ effect associated with the haloes that host the AGN is detected at the 5σ level through its spectral signature, representing a statistical detection of the SZ effect in some of the lowest mass haloes (average M 200 ≈ 10 13 M. h −1 70 ) studied to date. The relation between the SZ effect and mass (based on weak lensing measurements of radio galaxies) is consistent with that measured by Planck for local bright galaxies. In the context of galaxy evolution models, this study confirms that galaxies with radio AGN also typically support hot gaseous haloes. Adding Herschel observations allows us to show that the SZ signal is not significantly contaminated by dust emission. Finally, we analyse the contribution of radio sources to the angular power spectrum of the cosmic microwave background
A derivation of the free-free emission on the Galactic plane between l=20 and 44 degrees
We present the derivation of the free-free emission on the Galactic plane
between l=20 and 44 degrees and |b| < 4 degrees, using Radio Recombination Line
(RRL) data from the HI Parkes All-Sky Survey (HIPASS). Following an upgrade on
the RRL data reduction technique, which improves significantly the quality of
the final RRL spectra, we have extended the analysis to three times the area
covered in Alves et al. (2010). The final RRL map has an angular resolution of
14.8 arcmin and a velocity resolution of 20 km/s.
A map of the electron temperature (Te) of the ionised gas is derived for the
area under study using the line and continuum data from the present survey. The
mean Te on the Galactic plane is 6000 K. The first direct measure of the
free-free emission is obtained based on the derived Te map. Subtraction of this
thermal component from the total continuum leaves the first direct measure of
the synchrotron emission at 1.4 GHz. A narrow component of width 2 degrees is
identified in the latitude distribution of the synchrotron emission. We present
a list of HII regions and SNRs extracted from the present free-free and
synchrotron maps, where we confirm the synchrotron nature of three objects:
G41.12-0.21, G41.15+0.39 and G35.59-0.44. We also identify a bright (42 Jy) new
double radio galaxy, J1841-0152, previously unrecognised owing to the high
optical extinction in the region.
The latitude distribution for the RRL-derived free-free emission shows that
the WMAP Maximum Entropy Method (MEM) is too high by ~ 50 per cent, in
agreement with other recent results. The extension of this study to the inner
Galaxy region l=-50 to 50 degrees will allow a better overall comparison of the
RRL result with WMAP.Comment: 17 pages, 15 figures. Submitted to MNRA
Global economic impacts of climate variability and change during the 20th century
Estimates of the global economic impacts of observed climate change during the 20th century obtained by applying five impact functions of different integrated assessment models (IAMs) are separated into their main natural and anthropogenic components. The estimates of the costs that can be attributed to natural variability factors and to the anthropogenic intervention with the climate system in general tend to show that: 1) during the first half of the century, the amplitude of the impacts associated with natural variability is considerably larger than that produced by anthropogenic factors and the effects of natural variability fluctuated between being negative and positive. These non-monotonic impacts are mostly determined by the low-frequency variability and the persistence of the climate system; 2) IAMs do not agree on the sign (nor on the magnitude) of the impacts of anthropogenic forcing but indicate that they steadily grew over the first part of the century, rapidly accelerated since the mid 1970's, and decelerated during the first decade of the 21st century. This deceleration is accentuated by the existence of interaction effects between natural variability and natural and anthropogenic forcing. The economic impacts of anthropogenic forcing range in the tenths of percentage of the world GDP by the end of the 20th century; 3) the impacts of natural forcing are about one order of magnitude lower than those associated with anthropogenic forcing and are dominated by the solar forcing; 4) the interaction effects between natural and anthropogenic factors can importantly modulate how impacts actually occur, at least for moderate increases in external forcing. Human activities became dominant drivers of the estimated economic impacts at the end of the 20th century, producing larger impacts than those of low-frequency natural variability. Some of the uses and limitations of IAMs are discussed
Correlations in the (Sub)millimeter background from ACTxBLAST
We present measurements of the auto- and cross-frequency correlation power
spectra of the cosmic (sub)millimeter background at: 250, 350, and 500 um
(1200, 860, and 600 GHz) from observations made with the Balloon-borne Large
Aperture Submillimeter Telescope, BLAST; and at 1380 and 2030 um (218 and 148
GHz) from observations made with the Atacama Cosmology Telescope, ACT. The
overlapping observations cover 8.6 deg^2 in an area relatively free of Galactic
dust near the south ecliptic pole (SEP). The ACT bands are sensitive to
radiation from the CMB, the Sunyaev-Zel'dovich (SZ) effect from galaxy
clusters, and to emission by radio and dusty star-forming galaxies (DSFGs),
while the dominant contribution to the BLAST bands is from DSFGs. We confirm
and extend the BLAST analysis of clustering with an independent pipeline, and
also detect correlations between the ACT and BLAST maps at over 25sigma
significance, which we interpret as a detection of the DSFGs in the ACT maps.
In addition to a Poisson component in the cross-frequency power spectra, we
detect a clustered signal at >4sigma, and using a model for the DSFG evolution
and number counts, we successfully fit all our spectra with a linear clustering
model and a bias that depends only on redshift and not on scale. Finally, the
data are compared to, and generally agree with, phenomenological models for the
DSFG population. This study represents a first of its kind, and demonstrates
the constraining power of the cross-frequency correlation technique to
constrain models for the DSFGs. Similar analyses with more data will impose
tight constraints on future models.Comment: 17 pages, 11 figure
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