383 research outputs found
A deep wide-field sub-mm survey of the Carina Nebula complex
The Great Nebula in Carina is a superb location in which to study the physics
of violent massive star-formation and the resulting feedback effects, including
cloud dispersal and triggered star-formation. In order to reveal the cold dusty
clouds in the Carina Nebula complex, we used the Large APEX Bolometer Camera
LABOCA at the APEX telescope to map a 1.25 deg x 1.25 deg (= 50 x 50 pc^2)
region at 870 micrometer. From a comparison to Halpha images we infer that
about 6% of the 870 micrometer flux in the observed area is likely free-free
emission from the HII region, while about 94% of the flux is very likely
thermal dust emission. The total (dust + gas) mass of all clouds for which our
map is sensitive is ~ 60 000 Msun, in good agreement with the mass of the
compact clouds in this region derived from 13CO line observations. We generally
find good agreement in the cloud morphology seen at 870 micrometer and the
Spitzer 8 micrometer emission maps, but also identify a prominent infrared dark
cloud. Finally, we construct a radiative transfer model for the Carina Nebula
complex that reproduces the observed integrated spectral energy distribution
reasonably well. Our analysis suggests a total gas + dust mass of about 200000
Msun in the investigated area; most of this material is in the form of
molecular clouds, but a widely distributed component of (partly) atomic gas,
containing up to ~ 50% of the total mass, may also be present. Currently, only
some 10% of the gas is in sufficiently dense clouds to be immediately available
for future star formation, but this fraction may increase with time owing to
the ongoing compression of the strongly irradiated clouds and the expected
shockwaves of the imminent supernova explosions.Comment: Accepted for publication in Astronomy & Astrophysics; high-quality
pre-prints can be obtained from
http://www.usm.uni-muenchen.de/people/preibisch/publications.htm
A multiwavelength study of the star forming region IRAS 18544+0112
This work aims at investigating the molecular and infrared components in the
massive young stellar object (MYSO) candidate IRAS 18544+0112. The purpose is
to determine the nature and the origin of this infrared source. To analyze the
molecular gas towards IRAS 18544+0112, we have carried out observations in a
90" x 90" region around l = 34.69, b = -0.65, using the Atacama Submillimeter
Telescope Experiment (ASTE) in the 12CO J=3-2, 13CO J=3-2, HCO+ J=4-3 and CS
J=7-6 lines with an angular resolution of 22". The infrared emission in the
area has been analyzed using 2MASS and Spitzer public data. From the molecular
analysis, we find self-absorbed 12CO J=3-2 profiles, which are typical in star
forming regions, but we do not find any evidence of outflow activity. Moreover,
we do not detect either HCO+ J=4-3 or CS J=7-6 in the region, which are species
normally enhanced in molecular outflows and high density envelopes. The 12CO
J=3-2 emission profile suggests the presence of expanding gas in the region.
The Spitzer images reveal that the infrared source has a conspicuous extended
emission bright at 8 um with an evident shell-like morphology of ~ 1.5 arcmin
in size (~ 1.4 pc at the proposed distance of 3 kpc) that encircles the 24 um
emission. The non-detection of ionized gas related to IRAS 18544+0112, together
with the fact that it is still embedded in a molecular clump suggest that IRAS
18544+0112, has not reached the UCHII region stage yet. Based on near infrared
photometry we search for YSO candidates in the region and propos that 2MASS
18565878+0116233 is the infrared point source associated with IRAS 18544+0112.
Finally, we suggest that the expansion of a larger nearby HII region,
G034.8-0.7, might be related to the formation of IRAS 18544+0112.Comment: 14 pages, accepted for publication in A&A. Figures degraded to reduce
file siz
Multi-frequency study of supernova remnants in the Large Magellanic Cloud. Confirmation of the supernova remnant status of DEM L205
We present new X-ray and radio data of the LMC SNR candidate DEM L205,
obtained by XMM-Newton and ATCA, along with archival optical and infrared
observations. We use data at various wavelengths to study this object and its
complex neighbourhood, in particular in the context of the star formation
activity, past and present, around the source. We analyse the X-ray spectrum to
derive some remnant's properties, such as age and explosion energy. Supernova
remnant features are detected at all observed wavelengths: soft and extended
X-ray emission is observed, arising from a thermal plasma with a temperature kT
between 0.2 keV and 0.3 keV. Optical line emission is characterised by an
enhanced [SII]/Halpha ratio and a shell-like morphology, correlating with the
X-ray emission. The source is not or only tentatively detected at near-infrared
wavelengths (< 10 microns), but there is a detection of arc-like emission at
mid and far-infrared wavelengths (24 and 70 micron) that can be unambiguously
associated with the remnant. We suggest that thermal emission from dust heated
by stellar radiation and shock waves is the main contributor to the infrared
emission. Finally, an extended and faint non-thermal radio emission correlates
with the remnant at other wavelengths and we find a radio spectral index
between -0.7 and -0.9, within the range for SNRs. The size of the remnant is
~79x64 pc and we estimate a dynamical age of about 35000 years. We definitely
confirm DEM L205 as a new SNR. This object ranks amongst the largest remnants
known in the LMC. The numerous massive stars and the recent outburst in star
formation around the source strongly suggest that a core-collapse supernova is
the progenitor of this remnant. (abridged)Comment: 11 pages, 6 figures, accepted for publication in A&
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Environmental SLAPPs in the UK: threat or opportunity?
Strategic lawsuits against public participation (SLAPPs) brought against the environmental movement in the UK since the 1990s are examined. SLAPPs, a form of Green backlash, have been mobilised across a wide range of policy areas that have seen vigorous campaigning and protest by the movement, including roads, GMOs and, more recently, climate change. SLAPPs are typically regarded as a threat, designed to close down democratic free speech and protest. However, in the UK, there are some notable cases where the environmental movement has been able to use agency to convert what may appear as a legal threat into a positive legal or media opportunity
A molecular outflow evidencing star formation activity in the vicinity of the HII region G034.8-0.7 and the SNR W44
This work aims at investigating the molecular gas component in the vicinity
of two young stellar object (YSO) candidates identified at the border of the
HII region G034.8-0.7 that is evolving within a molecular cloud shocked by the
SNR W44. The purpose is to explore signatures of star forming activity in this
complex region. We performed a near and mid infrared study towards the border
of the HII region G034.8-0.7 and observed a 90" X 90" region near 18h 56m 48s,
+01d 18' 45" (J2000) using the Atacama Submillimeter Telescope Experiment
(ASTE) in the 12CO J=3--2, 13CO J=3--2, HCO+ J=4--3 and CS J=7--6 lines with an
angular resolution of 22". Based on the infrared study we propose that the
source 2MASS 18564827+0118471 (IR1 in this work) is a YSO candidate. We
discovered a bipolar 12CO outflow in the direction of the line of sight and a
HCO+ clump towards IR1, confirming that it is a YSO. From the detection of the
CS J=7--6 line we infer the presence of high density (>10^7 cm^-3) and warm
(>60 K) gas towards IR1, probably belonging to the protostellar envelope where
the YSO is forming. We investigated the possible genetic connection of IR1 with
the SNR and the HII region. By comparing the dynamical time of the outflows and
the age of the SNR W44, we conclude that the possibility of the SNR has
triggered the formation of IR1 is unlikely. On the other hand, we suggest that
the expansion of the HII region G034.8-0.7 is responsible for the formation of
IR1 through the "collect and collapse" process.Comment: 19 pages, 14 figures. Figures degraded to reduce file size. Accepted
06/02/2009 for publication in A&
Terminating ley with mid-summer bare fallow controls Elymus repens
The results of this study suggest that mid-summer bare fallow is a relative effective way to reduce the amount of Elymus repens when terminating ley. Early started stubble cultivation is also less sensitive to moist weather, leaving more time for exhausting the rhizome reserves of E. repens. Stubble cultivation and catch crop do increase the costs but not as much as bare fallowing for the whole summer would do. Additionally, mid summer bare fallow allows harvesting one forage yield prior to bare fallowing
Tekoäly ja syväoppiminen synteettisen biologian työkaluna
Tiivistelmä. Synteettinen biologia tarkoittaa biologisten järjestelmien tutkimusta keinotekoisten organismien avulla. Synteettisen biologian ala on alkuajoistaan lähtien kärsinyt orgaanisten järjestelmiensä vaatimien standardoitujen komponenttien puutteellisesta tuntemuksesta sekä niiden luomisen korkeista kustannuksista. Ongelmaa on kuitenkin ajan kuluessa helpottanut biologian ja tietotekniikan alojen lisääntynyt yhteensovittaminen sekä tietolaitteiden laskentatehon nopea kasvu. Tämä on luonut pohjan myös esimerkiksi korkean suorituskyvyn sekvensointimenetelmille ja tekoälypohjaisille tehokkaille työkaluille.
Synteettinen biologia on hyötynyt merkittävästi tekoälyn laajamittaisesta käyttöönotosta ja sen tuomista mahdollisuuksista useissa biologian sekä synteettisen biologian alojen sovelluksissa. Tekoäly on mahdollistanut esimerkiksi biomolekyylien rakenteiden ja vuorovaikutuksien perinpohjaisemman selvittämisen sekä synteettisten biokomponenttien tehokkaamman suunnittelun ja luomisen. Esimerkiksi kohdespesifisten synteettisten proteiinien luominen on jo mahdollista. Synteettisiä geenejä ja niiden säätelyalueita kyetään rakentamaan proteiinisynteesin hallitsemiseksi. Myös kokonaisten geenipiirien ja yksinkertaisten genomien suunnittelu on mahdollista esimerkiksi uudenlaisten protosolujen, eli yksinkertaistettujen synteettisten organismien toteuttamista varten. Tämän kehityksen ansiosta pystymme luomaan entistä monimutkaisempia synteettisen biologian järjestelmiä biologisten prosessien ymmärtämisen parantamiseksi sekä niiden hyödyntämiseksi esimerkiksi lääketieteen tai bioteollisuuden tarpeisiin.
Synteettisen biologian alalla on kuitenkin edelleen suuria haasteita tekoälyn täysimittaisen potentiaalin hyödyntämisessä. Tietoteknisten standardien yhteensovittaminen synteettisen biologian prosessien ja järjestelmien kanssa vaatii edelleen paljon työtä. Tekoälymallien koulutusta varten tarvitaan riittävästi laadukasta dataa. Tekoälytyökalut sekä niiden paljastamien yhä monimutkaisempien kokonaisuuksien käsittely ja ymmärtäminen voi vaatia entistä enemmän resursseja sekä organisaatio- että yksilötasolla. Etenkin syväoppivien tekoälymallien seurauksena tutkimuskohteisiin liittyvien ongelmien ulottuvuudet sekä niiden vaatima laskentateho voi kasvaa merkittävästi. Teknisten haasteiden lisäksi myös yhteiskunnalliset haasteet ovat merkittäviä. Synteettisen biologian ja tekoälyn herättämät eettiset kysymykset aiheuttavat yhä enemmän julkista keskustelua. Kansainvälinen lainsäädäntö ja yhteiset standardit ovatkin keskeisessä asemassa näiden voimakkaiden tieteenalojen hallitun kehittämisen takaamiseksi
A Critical Examination of the X-Wind Model for Chondrule and Calcium-rich, Aluminum-rich Inclusion Formation and Radionuclide Production
Meteoritic data, especially regarding chondrules and calcium-rich,
aluminum-rich inclusions (CAIs), and isotopic evidence for short-lived
radionuclides (SLRs) in the solar nebula, potentially can constrain how
planetary systems form. Intepretation of these data demands an astrophysical
model, and the "X-wind" model of Shu et al. (1996) and collaborators has been
advanced to explain the origin of chondrules, CAIs and SLRs. It posits that
chondrules and CAIs were thermally processed < 0.1 AU from the protostar, then
flung by a magnetocentrifugal outflow to the 2-3 AU region to be incorporated
into chondrites. Here we critically examine key assumptions and predictions of
the X-wind model. We find a number of internal inconsistencies: theory and
observation show no solid material exists at 0.1 AU; particles at 0.1 AU cannot
escape being accreted into the star; particles at 0.1 AU will collide at speeds
high enough to destroy them; thermal sputtering will prevent growth of
particles; and launching of particles in magnetocentrifugal outflows is not
modeled, and may not be possible. We also identify a number of incorrect
predictions of the X-wind model: the oxygen fugacity where CAIs form is orders
of magnitude too oxidizing; chondrule cooling rates are orders of magnitude
lower than those experienced by barred olivine chondrules; chondrule-matrix
complementarity is not predicted; and the SLRs are not produced in their
observed proportions. We conclude that the X-wind model is not relevant to
chondrule and CAI formation and SLR production. We discuss more plausible
models for chondrule and CAI formation and SLR production.Comment: Accepted for publication in The Astrophysical Journa
Metabolic Signatures of Adiposity in Young Adults: Mendelian Randomization Analysis and Effects of Weight Change
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Attribution: how is it relevant for loss and damage policy and practice?
Attribution has become a recurring issue in discussions about Loss and Damage (L&D). In this highly-politicised context, attribution is often associated with responsibility and blame; and linked to debates about liability and compensation. The aim of attribution science, however, is not to establish responsibility, but to further scientific understanding of causal links between elements of the Earth System and society. This research into causality could inform the management of climate-related risks through improved understanding of drivers of relevant hazards, or, more widely, vulnerability and exposure; with potential benefits regardless of political positions on L&D. Experience shows that it is nevertheless difficult to have open discussions about the science in the policy sphere. This is not only a missed opportunity, but also problematic in that it could inhibit understanding of scientific results and uncertainties, potentially leading to policy planning which does not have sufficient scientific evidence to support it. In this chapter, we first explore this dilemma for science-policy dialogue, summarising several years of research into stakeholder perspectives of attribution in the context of L&D. We then aim to provide clarity about the scientific research available, through an overview of research which might contribute evidence about the causal connections between anthropogenic climate change and losses and damages, including climate science, but also other fields which examine other drivers of hazard, exposure, and vulnerability. Finally, we explore potential applications of attribution research, suggesting that an integrated and nuanced approach has potential to inform planning to avert, minimise and address losses and damages. The key messages are
In the political context of climate negotiations, questions about whether losses and damages can be attributed to anthropogenic climate change are often linked to issues of responsibility, blame, and liability.
Attribution science does not aim to establish responsibility or blame, but rather to investigate drivers of change.
Attribution science is advancing rapidly, and has potential to increase understanding of how climate variability and change is influencing slow onset and extreme weather events, and how this interacts with other drivers of risk, including socio-economic drivers, to influence losses and damages.
Over time, some uncertainties in the science will be reduced, as the anthropogenic climate change signal becomes stronger, and understanding of climate variability and change develops.
However, some uncertainties will not be eliminated. Uncertainty is common in science, and does not prevent useful applications in policy, but might determine which applications are appropriate. It is important to highlight that in attribution studies, the strength of evidence varies substantially between different kinds of slow onset and extreme weather events, and between regions. Policy-makers should not expect the later emergence of conclusive evidence about the influence of climate variability and change on specific incidences of losses and damages; and, in particular, should not expect the strength of evidence to be equal between events, and between countries.
Rather than waiting for further confidence in attribution studies, there is potential to start working now to integrate science into policy and practice, to help understand and tackle drivers of losses and damages, informing prevention, recovery, rehabilitation, and transformation
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