81 research outputs found
SPIRE Map-Making Test Report
The photometer section of SPIRE is one of the key instruments on board of
Herschel. Its legacy depends very much on how well the scanmap observations
that it carried out during the Herschel mission can be converted to high
quality maps. In order to have a comprehensive assessment on the current status
of SPIRE map-making, as well as to provide guidance for future development of
the SPIRE scan-map data reduction pipeline, we carried out a test campaign on
SPIRE map-making. In this report, we present results of the tests in this
campaign.Comment: This document has an executive summary, 6 chapters, and 102 pages.
More information can be found at:
https://nhscsci.ipac.caltech.edu/sc/index.php/Spire/SPIREMap-MakingTest201
The emission by dust and stars of nearby galaxies in the Herschel KINGFISH survey
Using new far-infrared imaging from the Herschel Space Observatory with ancillary data from ultraviolet (UV) to submillimeter wavelengths, we estimate the total emission from dust and stars of 62 nearby galaxies in the KINGFISH survey in a way that is as empirical and model independent as possible. We collect and exploit these data in order to measure from the spectral energy distributions (SEDs) precisely how much stellar radiation is intercepted and re-radiated by dust, and how this quantity varies with galaxy properties. By including SPIRE data, we are more sensitive to emission from cold dust grains than previous analyses at shorter wavelengths, allowing for more accurate estimates of dust temperatures and masses. The dust/stellar flux ratio, which we measure by integrating the SEDs, has a range of nearly three decades (from 10(-2.2) to 10(0.5)). The inclusion of SPIRE data shows that estimates based on data not reaching these far-IR wavelengths are biased low by 17% on average. We find that the dust/stellar flux ratio varies with morphology and total infrared (IR) luminosity, with dwarf galaxies having faint luminosities, spirals having relatively high dust/stellar ratios and IR luminosities, and some early types having low dust/stellar ratios. We also find that dust/stellar flux ratios are related to gas-phase metallicity ((log(f(dust)/f(*)) over bar) = -0.66 +/- 0.08 and -0.22 +/- 0.12 for metal-poor and intermediate-metallicity galaxies, respectively), while the dust/stellar mass ratios are less so (differing by approximate to 0.2 dex); the more metal-rich galaxies span a much wider range of the flux ratios. In addition, the substantial scatter between dust/stellar flux and dust/stellar mass indicates that the former is a poor proxy of the latter. Comparing the dust/stellar flux ratios and dust temperatures, we also show that early types tend to have slightly warmer temperatures (by up to 5 K) than spiral galaxies, which may be due to more intense interstellar radiation fields, or possibly to different dust grain compositions. Finally, we show that early types and early-type spirals have a strong correlation between the dust/stellar flux ratio and specific star formation rate, which suggests that the relatively bright far-IR emission of some of these galaxies is due to ongoing (if limited) star formation as well as to the radiation field from older stars, which is heating the dust grains
Risk stratification in heart failure decompensation in the community: HEFESTOS score
Aims: Because evidence regarding risk stratification predicting prognosis of patients with heart failure (HF) decompensation attended in primary care is lacking, we developed and externally validated a model to forecast death/hospitalization during the first 30 days after an episode of decompensation. The predictive model is based on variables easily obtained in primary care settings. Methods and results: HEFESTOS is a multinational study consisting of a derivation cohort of HF patients recruited in 14 primary healthcare centres in Barcelona and a validation cohort from primary healthcare in 9 other European countries. The derivation and validation cohorts included 561 and 250 patients, respectively. Percentages of women in the derivation and validation cohorts were 56.3% and 47.6% (P = 0.026), respectively. Mean age was 82.2 years (SD 8.03) in the derivation cohort, and 79.3 years (SD 10.3) in the validation one (P = 0.001). HF with preserved ejection fraction represented 72.1% in the derivation cohort and 58.8% in the validation one (P = 0.004). Mortality/hospitalization during the first 30 days after a decompensation episode was 30.5% and 26% (P = 0.225) for the derivation and validation cohorts, respectively. Multivariable logistic regression models were performed to develop a score of risk. The identified predictors were worsening of dyspnoea [odds ratio (OR): 2.5; P = 0.001], orthopnoea (OR: 2.16; P = 0.01), paroxysmal nocturnal dyspnoea (OR: 2.25; P = 0.01), crackles (OR: 2.35; P = 0.01), New York Heart Association functional class III/IV (OR: 2.11; P = 0.001), oxygen saturation †90% (OR: 4.98; P 100 b.p.m. (OR: 2.72; P = 0.002), and previous hospitalization due to HF (OR: 2.45; P 20%. Outcome incidence was 2.7% for the low-risk group, 12.8% for medium risk, and 46.2% for high risk in the derivation cohort, and 9.1%, 12.9%, and 39.6% in the validation one. Conclusions: The HEFESTOS score, based on variables easily accessible in a community setting and validated in an external European cohort, properly predicted the risk of death/hospitalization during the first 30 days after an HF decompensation episode
Warm Dust and Spatially Variable PAH Emission in the Dwarf Starburst Galaxy NGC 1705
We present Spitzer observations of the dwarf starburst galaxy NGC 1705
obtained as part of SINGS. The galaxy morphology is very different shortward
and longward of ~5 microns: short-wavelength imaging shows an underlying red
stellar population, with the central super star cluster (SSC) dominating the
luminosity; longer-wavelength data reveals warm dust emission arising from two
off-nuclear regions offset by ~250 pc from the SSC. These regions show little
extinction at optical wavelengths. The galaxy has a relatively low global dust
mass (~2E5 solar masses, implying a global dust-to-gas mass ratio ~2--4 times
lower than the Milky Way average). The off-nuclear dust emission appears to be
powered by photons from the same stellar population responsible for the
excitation of the observed H Alpha emission; these photons are unassociated
with the SSC (though a contribution from embedded sources to the IR luminosity
of the off-nuclear regions cannot be ruled out). Low-resolution IRS
spectroscopy shows moderate-strength PAH emission in the 11.3 micron band in
the eastern peak; no PAH emission is detected in the SSC or the western dust
emission complex. There is significant diffuse 8 micron emission after scaling
and subtracting shorter wavelength data; the spatially variable PAH emission
strengths revealed by the IRS data suggest caution in the interpretation of
diffuse 8 micron emission as arising from PAH carriers alone. The metallicity
of NGC 1705 falls at the transition level of 35% solar found by Engelbracht and
collaborators; the fact that a system at this metallicity shows spatially
variable PAH emission demonstrates the complexity of interpreting diffuse 8
micron emission. A radio continuum non-detection, NGC 1705 deviates
significantly from the canonical far-IR vs. radio correlation. (Abridged)Comment: ApJ, in press; please retrieve full-resolution version from
http://www.astro.wesleyan.edu/~cannon/pubs.htm
The Nature of Infrared Emission in the Local Group Dwarf Galaxy NGC 6822 As Revealed by Spitzer
We present Spitzer imaging of the metal-deficient (Z ~30% Z_sun) Local Group
dwarf galaxy NGC 6822. On spatial scales of ~130 pc, we study the nature of IR,
H alpha, HI, and radio continuum emission. Nebular emission strength correlates
with IR surface brightness; however, roughly half of the IR emission is
associated with diffuse regions not luminous at H alpha (as found in previous
studies). The global ratio of dust to HI gas in the ISM, while uncertain at the
factor of ~2 level, is ~25 times lower than the global values derived for
spiral galaxies using similar modeling techniques; localized ratios of dust to
HI gas are about a factor of five higher than the global value in NGC 6822.
There are strong variations (factors of ~10) in the relative ratios of H alpha
and IR flux throughout the central disk; the low dust content of NGC 6822 is
likely responsible for the different H alpha/IR ratios compared to those found
in more metal-rich environments. The H alpha and IR emission is associated with
high-column density (> ~1E21 cm^-2) neutral gas. Increases in IR surface
brightness appear to be affected by both increased radiation field strength and
increased local gas density. Individual regions and the galaxy as a whole fall
within the observed scatter of recent high-resolution studies of the radio-far
IR correlation in nearby spiral galaxies; this is likely the result of depleted
radio and far-IR emission strengths in the ISM of this dwarf galaxy.Comment: ApJ, in press; please retrieve full-resolution version from
http://www.astro.wesleyan.edu/~cannon/pubs.htm
Spitzer and JCMT Observations of the Active Galactic Nucleus in the Sombrero Galaxy (NGC 4594)
We present Spitzer 3.6-160 micron images, Spitzer mid-infrared spectra, and
JCMT SCUBA 850 micron images of the Sombrero Galaxy (NGC 4594), an Sa galaxy
with a 10^9 M_solar low luminosity active galactic nucleus (AGN). The brightest
infrared sources in the galaxy are the nucleus and the dust ring. The spectral
energy distribution of the AGN demonstrates that, while the environment around
the AGN is a prominent source of mid-infrared emission, it is a relatively weak
source of far-infrared emission, as had been inferred for AGN in previous
research. The weak nuclear 160 micron emission and the negligible polycyclic
aromatic hydrocarbon emission from the nucleus also implies that the nucleus is
a site of only weak star formation activity and the nucleus contains relatively
little cool interstellar gas needed to fuel such activity. We propose that this
galaxy may be representative of a subset of low ionization nuclear emission
region galaxies that are in a quiescent AGN phase because of the lack of gas
needed to fuel circumnuclear star formation and Seyfert-like AGN activity.
Surprisingly, the AGN is the predominant source of 850 micron emission. We
examine the possible emission mechanisms that could give rise to the 850 micron
emission and find that neither thermal dust emission, CO line emission,
bremsstrahlung emission, nor the synchrotron emission observed at radio
wavelengths can adequately explain the measured 850 micron flux density by
themselves. The remaining possibilities for the source of the 850 micron
emission include a combination of known emission mechanisms, synchrotron
emission that is self-absorbed at wavelengths longer than 850 microns, or
unidentified spectral lines in the 850 micron band.Comment: Accepted to ApJ, 200
Biodiversitet implementert i landskapsarkitektur : et prosjekteksempel fra Asker sentrum
Norsk: Mer enn halvparten av jordens befolkning bor i urbane omrÄder og tallet Þker kraftig. Samtidig er vi vitner til den stÞrste utryddelsen av arter siden dinosaurene dÞde ut for 65 millioner Är siden. Det er i hovedsak menneskelig aktivitet som truer det biologiske mangfoldet gjennom tap, forringelse og fragmentering av habitat. Urbanisering og fortetting reduserer fragmentering av habitat, men dette gÄr ofte pÄ bekostning av grÞntomrÄdene. Denne oppgaven utforsker muligheter for Ä ivareta biologisk mangfold i et presset urbant omrÄde. Tematikken er hÞyst akuell, men fÄr for lite oppmerksomhet innen fagfeltet landskapsarkitektur til tross for landskapsarkitekters posisjon til direkte pÄvirkning av omgivelsene.
Oppgaven presenterer fÞrst anvendt kunnskap om biodiversitet i urbane omrÄder, og deretter omsettes kunnskapen til en verktÞykasse bestÄende av fem deler: landskapsÞkologiske prinsipper, menneskers preferanser i forhold til urban natur, tiltak for biodiversitet, artsvalg og vegetasjonsmodeller. Her legges det frem konkrete funn som ulike planters betydning for andre arter og hvordan man kan tilrettelegge for biodiversitet i grÞntanlegg. Videre fÞlger en analyse av Asker kommune fÞr verktÞykassen anvendes konseptuelt pÄ prosjekteksempelet Asker sentrum. Avslutningsvis fÞlger en diskusjon av oppgaven med hensyn pÄ problemstillingen der det pÄpekes en brist i kunnskapsformidling samt nÞdvendigheten av stÞrre grad av tverrfaglig samarbeid.
English:
More than half of the worldâs population is now living in urban areas and the number is constantly increasing. At the same time we are witnessing the greatest extinction of species since the dinosaurs died 65million years ago. It is mainly human activity that is causing this threat to loss of biodiversity through loss, degrading and fragmentation of habitat. Urbanization and densification reduces fragmentation of habitat, but this is often at the expence of the green areas. This thesis is exploring how to maintain biodiversity in urban areas under pressure. The topic is highly relevant, but rarely receive attention within the field of landscape architecture, despite the landscape architects position to directly shape the environments.
The thesis first presents utilized knowledge on biodiversity in urban areas and then the knowledge is put into a toolbox divided into five parts: landscape ecological principles, human preferences in urban nature, measures to enhance biodiversity, selection of species and models of vegetation. Here it is presented specific findings like plants different significance for other species and how to enhance biodiversity in a green area. Afterwards comes an analysis of Asker municipality before the toolbox is applied conceptually in the case study in Asker center. At the end follows a discussion of the whole thesis focused on the research question, where a shortcoming is addressed in the flow of knowledge, in addition to the necessity of greater interdisciplinary collaboration
Emission en infrarouge moyen des poussiÚres dans les galaxies spirales : liens avec la formation d'étoiles et avec la dynamique des galaxies barrées
The dust emission of a sample of 69 nearby spiral galaxies was studied through observations with the ISOCAM camera between 5 and 18 microns, comprising maps in two broadband filters allowing a morphological study and five low-resolution spectra, used to identify and separate the different emission components. The usefulness of two dust species as indicators of the star formation rate was established over five orders of magnitude in star formation rate density, together with the appropriate validity limits. The properties of strongly barred galaxies were also compared to those of weakly or non-barred galaxies and interpreted in the frame of hydrodynamical models. Physical parameters regulating mid-infrared color variations were extracted and discussed.Un Ă©chantillon de 69 galaxies spirales proches a Ă©tĂ© Ă©tudiĂ© Ă travers l'Ă©mission de la poussiĂšre, observĂ©e par la camĂ©ra ISOCAM entre 5 et 18 microns. Les cartes complĂštes dans deux filtres larges, permettant une Ă©tude morphologique, ainsi que cinq spectres Ă basse rĂ©solution, utiles pour identifier et sĂ©parer les diffĂ©rentes composantes d'Ă©mission, ont Ă©tĂ© analysĂ©s. Des rĂ©gions circumnuclĂ©aires de 1 Ă 4 kpc de diamĂštre, oĂč le rĂ©gime de chauffage de la poussiĂšre est distinct de celui des disques, ont Ă©tĂ© isolĂ©es.La validitĂ© de l'Ă©mission en infrarouge moyen en tant que traceur de la formation d'Ă©toiles a d'abord Ă©tĂ© examinĂ©e dans les disques, oĂč une seule phase de poussiĂšre domine (les porteurs des bandes aromatiques), puis cette Ă©tude a Ă©tĂ© Ă©tendue aux rĂ©gionscircumnuclĂ©aires, plus denses et actives, ainsi qu'Ă des galaxies Ă flambĂ©e de formation d'Ă©toiles, oĂč un continuum thermique se superpose aux bandes aromatiques. La rĂ©ponse de la poussiĂšre Ă la formation d'Ă©toiles a Ă©tĂ© explorĂ©e sur cinq ordres de grandeur.Par ailleurs, les propriĂ©tĂ©s des galaxies fortement barrĂ©es ont Ă©tĂ© comparĂ©es Ă celles des galaxies faiblement ou non barrĂ©es, et interprĂ©tĂ©es dans le cadre des modĂšles hydrodynamiques, qui prĂ©voient qu'un potentiel gravitationnel barrĂ© peut induire des Ă©coulements de gaz massifs vers les rĂ©gions centrales, avec des consĂ©quences indirectes sur l'activitĂ© stellaire et l'Ă©volution morphologique des galaxies isolĂ©es. Au cours de cette Ă©tude, quelques paramĂštres rĂ©gulant les variations des couleurs en infrarouge moyen ont Ă©tĂ© mis en relief
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