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- Caswell, J. L., et al.
(författare)
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The 6-GHz methanol multibeam maser catalogue - I. Galactic Centre region, longitudes 345° to 6°
- 2010
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Ingår i: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - 0035-8711. ; 404:2, s. 1029-1060
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Tidskriftsartikel (refereegranskat)abstract
- We have conducted a Galactic plane survey of methanol masers at 6668 MHz using a seven-beam receiver on the Parkes telescope. Here we present results from the first part, which provides sensitive unbiased coverage of a large region around the Galactic Centre. Details are given for 183 methanol maser sites in the longitude range 345° through the Galactic Centre to 6°. Within 6° of the Galactic Centre, we found 88 maser sites, of which more than half (48) are new discoveries. The masers are confined to a narrow Galactic latitude range, indicative of many sources at the Galactic Centre distance and beyond, and confined to a thin disc population; there is no high-latitude population that might be ascribed to the Galactic bulge. Within 2° of the Galactic Centre the maser velocities all lie between −60 and +77 km s−1, a range much smaller than the 540 km s−1 range observed in CO. Elsewhere, the maser with highest positive velocity (+107 km s−1) occurs, surprisingly, near longitude 355° and is probably attributable to the Galactic bar. The maser with the most negative velocity (−127 km s−1) is near longitude 346°, within the longitude–velocity locus of the near side of the ‘3-kpc arm’. It has the most extreme velocity of a clear population of masers associated with the near and far sides of the 3-kpc arm. Closer to the Galactic Centre the maser space density is generally low, except within 0.25 kpc of the Galactic Centre itself, the ‘Galactic Centre zone’, where it is 50 times higher, which is hinted at by the longitude distribution, and confirmed by the unusual velocities.
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- Tegtmeier, S., et al.
(författare)
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SPARC Data Initiative: A comparison of ozone climatologies from international satellite limb sounders
- 2013
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 118:21, s. 12229-12247
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Tidskriftsartikel (refereegranskat)abstract
- A comprehensive quality assessment of the ozone products from 18 limb-viewing satellite instruments is provided by means of a detailed intercomparison. The ozone climatologies in form of monthly zonal mean time series covering the upper troposphere to lower mesosphere are obtained from LIMS, SAGE I/II/III, UARS-MLS, HALOE, POAM II/III, SMR, OSIRIS, MIPAS, GOMOS, SCIAMACHY, ACE-FTS, ACE-MAESTRO, Aura-MLS, HIRDLS, and SMILES within 1978–2010. The intercomparisons focus on mean biases of annual zonal mean fields, interannual variability, and seasonal cycles. Additionally, the physical consistency of the data is tested through diagnostics of the quasi-biennial oscillation and Antarctic ozone hole. The comprehensive evaluations reveal that the uncertainty in our knowledge of the atmospheric ozone mean state is smallest in the tropical and midlatitude middle stratosphere with a 1σ multi-instrument spread of less than ±5%. While the overall agreement among the climatological data sets is very good for large parts of the stratosphere, individual discrepancies have been identified, including unrealistic month-to-month fluctuations, large biases in particular atmospheric regions, or inconsistencies in the seasonal cycle. Notable differences between the data sets exist in the tropical lower stratosphere (with a spread of ±30%) and at high latitudes (±15%). In particular, large relative differences are identified in the Antarctic during the time of the ozone hole, with a spread between the monthly zonal mean fields of ±50%. The evaluations provide guidance on what data sets are the most reliable for applications such as studies of ozone variability, model-measurement comparisons, detection of long-term trends, and data-merging activities.
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- Toohey, M., et al.
(författare)
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Characterizing sampling biases in the trace gas climatologies of the SPARC Data Initiative
- 2013
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Ingår i: Journal of Geophysical Research. - : American Geophysical Union (AGU). - 0148-0227 .- 2156-2202 .- 2169-897X .- 2169-8996. ; 118:20, s. 11847-11862
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Tidskriftsartikel (refereegranskat)abstract
- Monthly zonal mean climatologies of atmospheric measurements from satellite instruments can have biases due to the nonuniform sampling of the atmosphere by the instruments. We characterize potential sampling biases in stratospheric trace gas climatologies of the Stratospheric Processes and Their Role in Climate (SPARC) Data Initiative using chemical fields from a chemistry climate model simulation and sampling patterns from 16 satellite-borne instruments. The exercise is performed for the long-lived stratospheric trace gases O3 and H2O. Monthly sampling biases for O3 exceed 10% for many instruments in the high-latitude stratosphere and in the upper troposphere/lower stratosphere, while annual mean sampling biases reach values of up to 20% in the same regions for some instruments. Sampling biases for H2O are generally smaller than for O3, although still notable in the upper troposphere/lower stratosphere and Southern Hemisphere high latitudes. The most important mechanism leading to monthly sampling bias is nonuniform temporal sampling, i.e., the fact that for many instruments, monthly means are produced from measurements which span less than the full month in question. Similarly, annual mean sampling biases are well explained by nonuniformity in the month-to-month sampling by different instruments. Nonuniform sampling in latitude and longitude are shown to also lead to nonnegligible sampling biases, which are most relevant for climatologies which are otherwise free of biases due to nonuniform temporal sampling.
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- Oh, T. G., et al.
(författare)
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PRMT2 and ROR gamma Expression Are Associated With Breast Cancer Survival Outcomes
- 2014
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Ingår i: Molecular Endocrinology. - : The Endocrine Society. - 0888-8809 .- 1944-9917. ; 28:7, s. 1166-1185
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Tidskriftsartikel (refereegranskat)abstract
- Protein arginine methyltransferases (PRMTs) methylate arginine residues on histones and target transcription factors that play critical roles in many cellular processes, including gene transcription, mRNA splicing, proliferation, and differentiation. Recent studies have linked PRMT-dependent epigenetic marks and modifications to carcinogenesis and metastasis in cancer. However, the role of PRMT2-dependent signaling in breast cancer remains obscure. We demonstrate PRMT2 mRNA expression was significantly decreased in breast cancer relative to normal breast. Gene expression profiling, Ingenuity and protein-protein interaction network analysis after PRMT2-short interfering RNA transfection into MCF-7 cells, revealed that PRMT2-dependent gene expression is involved in cell-cycle regulation and checkpoint control, chromosomal instability, DNA repair, and carcinogenesis. For example, PRMT2 depletion achieved the following: 1) increased p21 and decreased cyclinD1 expression in (several) breast cancer cell lines, 2) decreased cell migration, 3) induced an increase in nucleotide excision repair and homologous recombination DNA repair, and 4) increased the probability of distance metastasis free survival (DMFS). The expression of PRMT2 and retinoid-related orphan receptor-gamma (ROR gamma) is inversely correlated in estrogen receptor-positive breast cancer and increased ROR gamma expression increases DMFS. Furthermore, we found decreased expression of the PRMT2-dependent signature is significantly associated with increased probability of DMFS. Finally, weighted gene coexpression network analysis demonstrated a significant correlation between PRMT2-dependent genes and cell-cycle checkpoint, kinetochore, and DNA repair circuits. Strikingly, these PRMT2-dependent circuits are correlated with pan-cancer metagene signatures associated with epithelial-mesenchymal transition and chromosomal instability. This study demonstrates the role and significant correlation between a histone methyltransferase (PRMT2)-dependent signature, ROR gamma, the cell-cycle regulation, DNA repair circuits, and breast cancer survival outcomes.
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- Hegglin, M. I., et al.
(författare)
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SPARC Data Initiative: Comparison of water vapor climatologies from international satellite limb sounders
- 2013
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Ingår i: Journal of Geophysical Research. - : American Geophysical Union (AGU). - 0148-0227 .- 2156-2202 .- 2169-897X. ; 118:20, s. 0148-0227
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Tidskriftsartikel (refereegranskat)abstract
- Within the SPARC Data Initiative, the first comprehensive assessment of the quality of 13 water vapor products from 11 limb-viewing satellite instruments (LIMS, SAGE II, UARS-MLS, HALOE, POAM III, SMR, SAGE III, MIPAS, SCIAMACHY, ACE-FTS, and Aura-MLS) obtained within the time period 1978–2010 has been performed. Each instrument's water vapor profile measurements were compiled into monthly zonal mean time series on a common latitude-pressure grid. These time series serve as basis for the “climatological” validation approach used within the project. The evaluations include comparisons of monthly or annual zonal mean cross sections and seasonal cycles in the tropical and extratropical upper troposphere and lower stratosphere averaged over one or more years, comparisons of interannual variability, and a study of the time evolution of physical features in water vapor such as the tropical tape recorder and polar vortex dehydration. Our knowledge of the atmospheric mean state in water vapor is best in the lower and middle stratosphere of the tropics and midlatitudes, with a relative uncertainty of ±2–6% (as quantified by the standard deviation of the instruments' multiannual means). The uncertainty increases toward the polar regions (±10–15%), the mesosphere (±15%), and the upper troposphere/lower stratosphere below 100 hPa (±30–50%), where sampling issues add uncertainty due to large gradients and high natural variability in water vapor. The minimum found in multiannual (1998–2008) mean water vapor in the tropical lower stratosphere is 3.5 ppmv (±14%), with slightly larger uncertainties for monthly mean values. The frequently used HALOE water vapor data set shows consistently lower values than most other data sets throughout the atmosphere, with increasing deviations from the multi-instrument mean below 100 hPa in both the tropics and extratropics. The knowledge gained from these comparisons and regarding the quality of the individual data sets in different regions of the atmosphere will help to improve model-measurement comparisons (e.g., for diagnostics such as the tropical tape recorder or seasonal cycles), data merging activities, and studies of climate variability.
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- Wickert, J, et al.
(författare)
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GNSS for Global Earth Observation: The European coordination action Gfg²
- 2012
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Ingår i: Sixth FORMOSAT-3/COSMIC Data Users' Workshop 30 October - 1 November 2012, Boulder, Colorado U.S.A..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Gfgsquared (GfG²) project is an international research related project with focus to the use of GNSS (Global Navigation Satellite Systems) for Earth Observation in a more general sense. Within the project novel GNSS applications with outstanding social importance are identified. These applications can be classified by the nine Social Benefit Areas (SBA), which address the current crucial problems of mankind: disasters, health, energy, climate, water, weather, ecosystems, agriculture, biodiversity (see www.earthobservation.org). We give examples for GNSS applications in the different SBA. For several of these applications, GNSS radio occultation is a key observation technique with several applications in that context.
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