| 1. |
- Coutens, A., et al.
(författare)
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The ALMA-PILS survey: First detections of deuterated formamide and deuterated isocyanic acid in the interstellar medium
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 590
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Tidskriftsartikel (refereegranskat)abstract
- Formamide (NH2CHO) has previously been detected in several star-forming regions and is thought to be a precursor for different prebiotic molecules. Its formation mechanism is still debated, however. Observations of formamide, related species, and their isopotologues may provide useful clues to the chemical pathways leading to their formation. The Protostellar Interferometric Line Survey (PILS) represents an unbiased, high angular resolution and sensitivity spectral survey of the low-mass protostellar binary IRAS 16293-2422 with the Atacama Large Millimeter/submillimeter Array (ALMA). For the first time, we detect the three singly deuterated forms of NH2CHO (NH2CDO, cis-and trans-NHDCHO), as well as DNCO towards the component B of this binary source. The images reveal that the different isotopologues are all present in the same region. Based on observations of the 13C isotopologues of formamide and a standard 12C/13C ratio, the deuterium fractionation is found to be similar for the three different forms with a value of about 2%. The DNCO/HNCO ratio is also comparable to the D/H ratio of formamide (~1%). These results are in agreement with the hypothesis that NH2CHO and HNCO are chemically related through grain-surface formation.
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| 2. |
- Jorgensen, J. K., et al.
(författare)
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The ALMA Protostellar Interferometric Line Survey (PILS) First results from an unbiased submillimeter wavelength line survey of the Class 0 protostellar binary IRAS 16293-2422 with ALMA
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 595, s. Art no A117-
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Tidskriftsartikel (refereegranskat)abstract
- Context. The inner regions of the envelopes surrounding young protostars are characterized by a complex chemistry, with prebiotic molecules present on the scales where protoplanetary disks eventually may form. The Atacama Large Millimeter/submillimeter Array (ALMA) provides an unprecedented view of these regions zooming in on solar system scales of nearby protostars and mapping the emission from rare species. Aims. The goal is to introduce a systematic survey, the Protostellar Interferometric Line Survey (PILS), of the chemical complexity of one of the nearby astrochemical templates, the Class 0 protostellar binary IRAS 16293 2422, using ALMA in order to understand the origin of the complex molecules formed in its vicinity. In addition to presenting the overall survey, the analysis in this paper focuses on new results for the prebiotic molecule glycolaldehyde, its isomers, and rarer isotopologues and other related molecules. Methods. An unbiased spectral survey of IRAS 16293 2422 covering the full frequency range from 329 to 363 GHz (0.8 mm) has been obtained with ALMA, in addition to a few targeted observations at 3.0 and 1.3 mm. The data consist of full maps of the protostellar binary system with an angular resolution of 0.5 '' (60 AU diameter), a spectral resolution of 0.2 km s(-1), and a sensitivity of 4-5 mJy beam(-1) km s(-1), which is approximately two orders of magnitude better than any previous studies. Results. More than 10 000 features are detected toward one component in the protostellar binary, corresponding to an average line density of approximately one line per 3 km s(-1). Glycolaldehyde; its isomers, methyl formate and acetic acid; and its reduced alcohol, ethylene glycol, are clearly detected and their emission well-modeled with an excitation temperature of 300 K. For ethylene glycol both lowest state conformers, aGg' and gGg', are detected, the latter for the first time in the interstellar medium (ISM). The abundance of glycolaldehyde is comparable to or slightly larger than that of ethylene glycol. In comparison to the Galactic Center these two species are over-abundant relative to methanol, possibly an indication of formation of the species at low temperatures in CO-rich ices during the infall of the material toward the central protostar. Both C-13 and the deuterated isotopologues of glycolaldehyde are detected, also for the first time ever in the ISM. For the deuterated species, a D/H ratio of approximate to 5% is found with no differences between the deuteration in the different functional groups of glycolaldehyde, in contrast to previous estimates for methanol and recent suggestions of significant equilibration between water and-OH functional groups at high temperatures. Measurements of the C-13-species lead to a C-12:C-13 ratio of approximate to 30, lower than the typical ISM value. This low ratio may reflect an enhancement of (CO)-C-13 in the ice due to either ion-molecule reactions in the gas before freeze-out or to differences in the temperatures where (CO)-C-12 and (CO)-C-13 ices sublimate. Conclusions. The results reinforce the importance of low-temperature grain surface chemistry for the formation of prebiotic molecules seen here in the gas after sublimation of the entire ice mantle. Systematic surveys of the molecules thought to be chemically related, as well as the accurate measurements of their isotopic composition, hold strong promise for understanding the origin of prebiotic molecules in the earliest stages of young stars.
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| 3. |
- Lykke, J. M., et al.
(författare)
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The ALMA-PILS survey: First detections of ethylene oxide, acetone and propanal toward the low-mass protostar IRAS 16293-2422
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 597, s. A53-
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Tidskriftsartikel (refereegranskat)abstract
- Context. One of the open questions in astrochemistry is how complex organic and prebiotic molecules are formed. The unsurpassed sensitivity of the Atacama Large Millimeter/submillimeter Array (ALMA) takes the quest for discovering molecules in the warm and dense gas surrounding young stars to the next level. Aims. Our aim is to start the process of compiling an inventory of oxygen-bearing complex organic molecules toward the solar-type Class 0 protostellar binary IRAS 16293-2422 from an unbiased spectral survey with ALMA, Protostellar Interferometric Line Survey (PILS). Here we focus on the new detections of ethylene oxide (c-C2H4O), acetone (CH3COCH3), and propanal (C2H5CHO). Methods. With ALMA, we surveyed the spectral range from 329 to 363 GHz at 0.5? (60 AU diameter) resolution. Using a simple model for the molecular emission in local thermodynamical equilibrium, the excitation temperatures and column densities of each species were constrained. Results. We successfully detect propanal (44 lines), ethylene oxide (20 lines) and acetone (186 lines) toward one component of the protostellar binary, IRAS 16293B. The high resolution maps demonstrate that the emission for all investigated species originates from the compact central region close to the protostar. This, along with a derived common excitation temperature of Tex ? 125 K, is consistent with a coexistence of these molecules in the same gas. Conclusions. The observations mark the first detections of acetone, propanal and ethylene oxide toward a low-mass protostar. The relative abundance ratios of the two sets of isomers, a CH3COCH3/C2H5CHO ratio of 8 and a CH3CHO/c-C2H4O ratio of 12, are comparable to previous observations toward high-mass protostars. The majority of observed abundance ratios from these results as well as those measured toward high-mass protostars are up to an order of magnitude above the predictions from chemical models. This may reflect either missing reactions or uncertain rates in the chemical networks. The physical conditions, such as temperatures or densities, used in the models, may not be applicable to solar-type protostars either.
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| 4. |
- Fayolle, E. C., et al.
(författare)
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Protostellar and cometary detections of organohalogens
- 2017
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Ingår i: Nature Astronomy. - : Springer Science and Business Media LLC. - 2397-3366. ; 1:10, s. 703-708
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Tidskriftsartikel (refereegranskat)abstract
- Organohalogens, a class of molecules that contain at least one halogen atom bonded to carbon, are abundant on the Earth where they are mainly produced through industrial and biological processes(1). Consequently, they have been proposed as biomarkers in the search for life on exoplanets(2). Simple halogen hydrides have been detected in interstellar sources and in comets, but the presence and possible incorporation of more complex halogen-containing molecules such as organohalogens into planet-forming regions is uncertain(3,4). Here we report the interstellar detection of two isotopologues of the organohalogen CH3Cl and put some constraints on CH3F in the gas surrounding the low-mass protostar IRAS 16293-2422, using the Atacama Large Millimeter/submillimeter Array (ALMA). We also find CH3Cl in the coma of comet 67P/Churyumov-Gerasimenko (67P/C-G) by using the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument. The detections reveal an efficient pre-planetary formation pathway of organohalogens. Cometary impacts may deliver these species to young planets and should thus be included as a potential abiotical production source when interpreting future organohalogen detections in atmospheres of rocky planets.
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| 5. |
- Ingemarsdotter, C K, et al.
(författare)
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Low-dose paclitaxel synergizes with oncolytic adenoviruses via mitotic slippage and apoptosis in ovarian cancer.
- 2010
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 0950-9232 .- 1476-5594. ; 29:45, s. 6051-63
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Tidskriftsartikel (refereegranskat)abstract
- The microtubule-stabilizing drug paclitaxel has activity in relapsed ovarian cancer. dl922-947, an oncolytic adenovirus with a 24-bp deletion in E1A CR2, replicates selectively within and lyses cells with a dysregulated Rb pathway and has efficacy in ovarian cancer. In the aggressive A2780CP xenograft, combination treatment with weekly dl922-947 and paclitaxel has significantly greater efficacy than either treatment alone and can produce complete tumor eradication in some animals. We investigated the mechanisms of paclitaxel's synergy with dl922-947 in ovarian cancer. The host-cell microtubule network is grossly rearranged and stabilized following adenovirus infection, but paclitaxel does not increase this significantly. Paclitaxel does not synergize by increasing infectivity, viral protein expression or virus release. However, destabilizing the microtubule network with nocodazole reduces viral exit, revealing a novel microtubule-dependent pathway for non-lytic adenoviral exit. dl922-947 can override multiple cell cycle checkpoints but induces cell death by a non-apoptotic mechanism. In combination, dl922-947 and low-dose paclitaxel induces aberrant, multipolar mitoses, mitotic slippage and multinucleation, triggering an apoptotic cell death.
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| 6. |
- Mc Kee, K J, et al.
(författare)
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The COPE index - A first stage assessment of negative impact, positive value and quality of support of caregiving in informal carers of older people
- 2003
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Ingår i: Aging & Mental Health. - : Informa UK Limited. - 1360-7863 .- 1364-6915. ; 7:1, s. 39-52
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Tidskriftsartikel (refereegranskat)abstract
- Data was collected in five countries from informal carers of older people (n=577) via a common protocol. Carers completed: (1) a 17-item version of the Carers of Older People in Europe (COPE) Index, an assessment of carers' perceptions of their role, (2) a questionnaire on demographic and caregiving circumstances, and (3) three instruments included for the criterion validation of the COPE Index (the General Health Questionnaire, the Hospital Anxiety and Depression Scale, and the World Health Organization Quality of Life-BREF). Principal Component Analysis of the COPE Index was followed by internal consistency analysis of emergent components. Scales derived by summing items loading on the components were analyzed for their association with the criterion measures. Two components, negative impact and positive value, emerged consistently across countries. A third component, quality of support was less consistent across countries. Scales derived from the negative impact and positive value components were internally consistent and significantly associated with the criterion validity measures. These two scales and four items drawn from the quality of support component were retained in the final COPE Index. While further testing is required, the COPE Index has current utility in increasing understanding of the role perceptions of carers of older people.
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| 7. |
- Weber, G, et al.
(författare)
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The phospholipase C b 3 gene located in the MEN 1 region shows loss of expression in endocrine tumors
- 1994
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 3:10, s. 1775-1781
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Tidskriftsartikel (refereegranskat)abstract
- Oncogenesis of tumours related to multiple endocrine neoplasia type 1 (MEN1) is associated with somatic deletions involving the MEN1 locus, suggesting inactivation of a tumour suppressor gene in this region. Identification of meiotic cross-overs in MEN1 families has placed the MEN1 locus centromeric of D11S807. An extended deletion mapping was performed in 27 primary parathyroid tumours, and identified D11S427 as the closest centromeric flanking marker. Through physical mapping using newly isolated cDNA clones, we estimated the distance between the flanking markers D11S807 and D11S427 to be less than 900 kb. One of these cDNA clones showed expression of a 4.4 kb message in multiple tissues, including those affected in MEN1, while in five endocrine tumours no transcript was detected. Sequence characterization showed that this gene encodes for the phospholipase C beta 3, a key enzyme in signal transduction.
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| 8. |
- Einig, Lucas, et al.
(författare)
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Deep learning denoising by dimension reduction: Application to the ORION-B line cubes
- 2023
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 677
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Tidskriftsartikel (refereegranskat)abstract
- Context. The availability of large bandwidth receivers for millimeter radio telescopes allows for the acquisition of position-position-frequency data cubes over a wide field of view and a broad frequency coverage. These cubes contain a lot of information on the physical, chemical, and kinematical properties of the emitting gas. However, their large size coupled with an inhomogenous signal-to-noise ratio (S/N) are major challenges for consistent analysis and interpretation. Aims. We searched for a denoising method of the low S/N regions of the studied data cubes that would allow the low S/N emission to be recovered without distorting the signals with a high S/N. Methods. We performed an in-depth data analysis of the 13CO and C17O (1-0) data cubes obtained as part of the ORION-B large program performed at the IRAM 30 m telescope. We analyzed the statistical properties of the noise and the evolution of the correlation of the signal in a given frequency channel with that of the adjacent channels. This has allowed us to propose significant improvements of typical autoassociative neural networks, often used to denoise hyperspectral Earth remote sensing data. Applying this method to the 13CO (1-0) cube, we were able to compare the denoised data with those derived with the multiple Gaussian fitting algorithm ROHSA, considered as the state-of-the-art procedure for data line cubes. Results. The nature of astronomical spectral data cubes is distinct from that of the hyperspectral data usually studied in the Earth remote sensing literature because the observed intensities become statistically independent beyond a short channel separation. This lack of redundancy in data has led us to adapt the method, notably by taking into account the sparsity of the signal along the spectral axis. The application of the proposed algorithm leads to an increase in the S/N in voxels with a weak signal, while preserving the spectral shape of the data in high S/N voxels. Conclusions. The proposed algorithm that combines a detailed analysis of the noise statistics with an innovative autoencoder architecture is a promising path to denoise radio-astronomy line data cubes. In the future, exploring whether a better use of the spatial correlations of the noise may further improve the denoising performances seems to be a promising avenue. In addition, dealing with the multiplicative noise associated with the calibration uncertainty at high S/N would also be beneficial for such large data cubes.
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| 9. |
- Elsner, J., et al.
(författare)
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Deep acceptors trapped at threading-edge dislocations in GaN
- 1998
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 58:19, s. 12571-12574
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Tidskriftsartikel (refereegranskat)abstract
- Local-density-functional methods are used to examine the behavior of the oxygen defect, gallium vacancy, and related defect complexes trapped at threading-edge dislocations in GaN. These defects are found to be particularly stable at the core of the dislocation where oxygen sits twofold coordinated in a bridge position. VGa-ON is found to be a deep double acceptor, VGa-(ON)2 is a deep single acceptor, and VGa-(ON)3 at the dislocation core is electrically inactive. We suggest that the first two defects are responsible for a deep acceptor level associated with the midgap yellow luminescence band.
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| 10. |
- Elsner, J., et al.
(författare)
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Structural and electrical properties of threading dislocations in GaN
- 1997
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Ingår i: Defects in semiconductors. - : Trans Tech Publications Inc.. ; , s. 1203-1210
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Konferensbidrag (refereegranskat)abstract
- The atomic structures and electrical properties for threading screw and threading edge dislocations of wurtzite GaN are calculated within the local-density approximation. Both dislocations are electrically inactive with a band gap free from deep levels. These results are understood to arise from relaxed core structures which are similar to (1010) surfaces. The threading screw dislocations are found to be stable with an open-core whereas the threading edge dislocations possess filled cores.
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