| 1. |
- Mlynczak, Martin G., et al.
(författare)
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Observations of the O(3P) fine structure line at 63 μm in the upper mesosphere and lower thermosphere
- 2004
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Ingår i: Journal of Geophysical Research - Space Physics. - 2169-9380 .- 2169-9402. ; 109:A12
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Tidskriftsartikel (refereegranskat)abstract
- Observations of the O(3P) fine structure line at 63 μm originating in the upper mesosphere and lower thermosphere have been obtained by the far-infrared spectrometer (FIRS-2) instrument, a Fourier transform spectrometer that flies periodically on high-altitude balloons. FIRS-2 primarily observes stratospheric ozone photochemistry using the technique of limb emission spectroscopy. As part of the routine operation of FIRS-2, up-looking views are made, during which the emission from the atomic oxygen is recorded. Using the Mass Spectrometer Incoherent Scatter (MSIS) empirical model to provide temperature and atomic oxygen concentrations, we compute radiances for comparison with the FIRS-2 observations. The computed radiances agree with the FIRS-2 measurements, which encompass 31 observations during nine flights over a span of 14 years, to within 10% on average, with 23 of the 31 observations agreeing to within measurement and calculation uncertainty. The consistency between the observed and computed radiances suggests that the MSIS model provides a reasonably accurate representation of temperature and atomic oxygen in the upper mesosphere and lower thermosphere.
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| 2. |
- Beral, V, et al.
(författare)
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Alcohol, tobacco and breast cancer - collaborative reanalysis of individual data from 53 epidemiological studies, including 58515 women with breast cancer and 95067 women without the disease
- 2002
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Ingår i: British Journal of Cancer. - : Springer Science and Business Media LLC. - 1532-1827 .- 0007-0920. ; 87, s. 1234-45
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Tidskriftsartikel (refereegranskat)abstract
- Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58515 women with invasive breast cancer and 95067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19 - 1.45, P < 0.00001) for an intake of 35 - 44 g per day alcohol, and 1.46 (1.33 - 1.61, P < 0.00001) for greater than or equal to 45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1 % per 10 g per day, P < 0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers= 1.03, 95% CI 0.98 - 1.07, and for current smokers=0.99, 0.92 - 1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver. (C) 2002 Cancer Research UK.
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| 3. |
- Ceballos, Eva, et al.
(författare)
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c-Myc antagonizes the effect of p53 on apoptosis and p21WAF1 transactivation in K562 leukemia cells
- 2000
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 0950-9232 .- 1476-5594. ; 19, s. 2194-2204
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Tidskriftsartikel (refereegranskat)abstract
- c-myc protooncogene positively regulates cell proliferation and overexpression of c-myc is found in many solid tumors and leukemias. In the present study we used the K562 human myeloid leukemia cell line as a model to study the functional interaction between c-Myc and p53. Using two different methods, we generated K562 transfectant cell lines with conditional expression of either c-Myc or p53. The cells expressed the p53Vall35 mutant, which adopts a wild-type conformation at 32 degrees C, while c-Myc induction was achieved with a zinc-inducible expression vector. We found that p53 in wild-type conformation induces growth arrest and apoptosis of K562. Expression of c-Myc significantly attenuated apoptosis and impaired the transcriptional activity of p53 on p21WAF1, Bax and cytomegalovirus promoters. The impairment of p21WAF1 transactivation by c-Myc was confirmed by transfection of a c-Myc-estrogen receptor fusion protein and by induction of c-myc by zinc in transfected cells. Also, p53-mediated up-regulation of p21WAF1 mRNA protein were significantly reduced by c-Myc, while Bax levels were unaffected. Consistently, c-Myc increased cyclin-dependent kinase 2 activity in K562 cells expressing p53 in wild-type conformation. These results suggest that c-Myc overexpression may antagonize the pro-apoptotic function of p53, thus providing a molecular mechanism for the frequently observed deregulation of c-myc in human cancer.
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| 4. |
- Echle, Georg, et al.
(författare)
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Optimized spectral microwindows for data analysis of the Michelson Interferometer for Passive Atmospheric Sounding on the Environmental Satellite
- 2000
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 39:30, s. 5531-
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Tidskriftsartikel (refereegranskat)abstract
- For data analysis of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) atmospheric limb emission spectroscopic experiment on Environmental Satellite microwindows, i.e., small spectral regions for data analysis, have been defined and optimized. A novel optimization scheme has been developed for this purpose that adjusts microwindow boundaries such that the total retrieval error with respect to measurement noise, parameter uncertainties, and systematic errors is minimized. Dedicated databases that contain optimized microwindows for retrieval of vertical profiles of pressure and temperature, H2O, O3, HNO3, CH4, N2O, and NO2 have been generated. Furthermore, a tool for optimal selection of subsets of predefined microwindows for specific retrieval situations has been provided. This tool can be used further for estimating total retrieval errors for a selected microwindow subset. It has been shown by use of this tool that an altitude-dependent definition of microwindows is superior to an altitude-independent definition. For computational efficiency a dedicated microwindow-related list of spectral lines has been defined that contains only those spectral lines that are of relevance for MIPAS limb sounding observations.
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| 5. |
- Funke, Bernd, et al.
(författare)
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New non-LTE retrieval method for atmospheric parameters from MIPAS/ENVISAT emission spectra at 5.3 μm
- 2002
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 4539, s. 396-405
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Tidskriftsartikel (refereegranskat)abstract
- Atmospheric emissions at 5.3 μm will be measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), a high-resolution limb sounder on board the European polar platform ENVISAT, scheduled to be launched in 2001. Measured spectra at 5.3 μm contain information on important atmospheric quantities such as NO volume mixing ratio, thermospheric temperature, and chemical NO production rates. However, the scientific analysis of this spectral region has to deal with complex non-local thermodynamic equilibrium (non-LTE) effects. A conventional non-LTE retrieval approach using ab initio vibrational temperatures cannot be applied due to rotational and spin-orbit non-LTE of NO in the thermosphere, and the dependence of NO state populations on the NO abundance itself caused by chemical excitations. An innovative non-LTE retrieval method enabling the treatment of vibrational, rotational, and spin non-LTE as well as a dependence of the non-LTE state distribution on the retrieval target quantities has thus been developed for the MIPAS data analysis. The ability of the developed non-LTE inversion tool to retrieve NO abundance profiles, thermospheric temperature profiles, and NO mean production rates by NO2 photolysis in the stratosphere and N+O2 combination in the thermosphere is demonstrated by means of a feasibility study.
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| 6. |
- Kaufmann, M., et al.
(författare)
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Satellite observations of daytime and nighttime ozone in the mesosphere and lower thermosphere
- 2003
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 108:9
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Tidskriftsartikel (refereegranskat)abstract
- The global distribution of mesospheric and lower thermospheric ozone 9.6 μm infrared emissions was measured by the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) experiment during two Space Shuttle missions in November 1994 and August 1997. The radiances measured by CRISTA have been inverted to O3 number densities in the 50-95 km range by using a nonlocal thermodynamic equilibrium model. A detailed sensitivity study of retrieved O3 number densities has been carried out. The ozone abundance profiles show volume mixing ratios of 1-2 ppmv at the stratopause, 0.5 ppmv or less around 80 km, and typically 1 ppmv during daytime and 10 ppmv during nighttime at the secondary maximum. The agreement with other experiments is typically better than 25%. The global distribution of upper mesospheric ozone shows significant latitudinal gradients and an enhancement in the equatorial upper mesosphere. At the polar night terminator a third ozone maximum is observed. Three-dimensional model results indicate that the latitudinal gradients are significantly influenced by solar tides.
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| 7. |
- López-Puertas, M., et al.
(författare)
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Non-LTE studies for the analysis of MIPAS/ENVISAT data
- 2002
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 4539, s. 381-395
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Tidskriftsartikel (refereegranskat)abstract
- The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a high-resolution limb sounder on board the European polar platform ENVISAT, scheduled for launch late in 2001. Three main characteristics converge in MIPAS which make it a very useful instrument for non-LTE studies: its wide spectral coverage (4.15-14.6 μm or 680-2275 cm-1); high spectral resolution (0.03 cm-1), and high sensitivity; all of this in addition to its global spatial coverage. In this paper we present an overview of the non-LTE studies that have been carried out in preparation for the analysis of MIPAS data, including the evaluation of non-LTE effects in the operational processing, focussed in the stratosphere, and the retrieval of species that normally emit under non-LTE conditions. The current mission plan for measuring the non-LTE upper atmosphere is described, as well as the general purpose non-LTE retrieval scheme developed for analyzing those measurements.
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| 8. |
- Mlynczak, Marty, et al.
(författare)
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The natural thermostat of nitric oxide emission at 5.3 μm in the thermosphere observed during the solar storms of April 2002
- 2003
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 30:21
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Tidskriftsartikel (refereegranskat)abstract
- The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment on the Thermosphere-Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite observed the infrared radiative response of the thermosphere to the solar storm events of April 2002. Large radiance enhancements were observed at 5.3 μm, which are due to emission from the vibration-rotation bands of nitric oxide (NO). The emission by NO is indicative of the conversion of solar energy to infrared radiation within the atmosphere and represents a "natural thermostat" by which heat and energy are efficiently lost from the thermosphere to space and to the lower atmosphere. We describe the SABER observations at 5.3 μm and their interpretation in terms of energy loss. The infrared enhancements remain only for a few days, indicating that such perturbations to the thermospheric state, while dramatic, are short-lived. Copyright 2003 by the American Geophysical Union.
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| 9. |
- Singh, Y, et al.
(författare)
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Approaches to increasing yield in evaporation/condensation nanoparticle generation
- 2002
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Ingår i: Journal of Aerosol Science. - 0021-8502. ; 33:9, s. 1309-1325
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Tidskriftsartikel (refereegranskat)abstract
- With the recent interest in the chemical, electronic and optical properties of nanometer scale metal particles, there is now interest in manufacturing these materials in larger quantities. Since both small particle size and high particle number concentrations are sought, there is a need for improved. particle generation reactors that can realize both goals. Here, results are presented for the synthesis of indium metal nanoparticles in an evaporation/condensation aerosol generator. Size distributions were measured for metal nanoparticles formed using a standard flow configuration, as well as using several variations on the standard configuration. The aim of the modifications is to increase the cooling rate and thus, to increase the nucleation rate of the nanoparticles. An increase in the number concentration of particles and, in some cases, a significant decrease in average particle size was observed when the modified reactor configurations were used. These results can be explained by the changes in the time-temperature history of the nanoparticles resulting from the modifications to the aerosol generator. A monodisperse model of nanoparticle formation and growth, accounting for nucleation, condensation and coagulation, was used to describe particle formation in the standard flow configuration, to guide the modifications, and to describe particle formation in one of the modified configurations, with qualitative agreement seen between measured and predicted particle sizes. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 10. |
- Von Clarmann, T., et al.
(författare)
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A blind test retrieval experiment for infrared limb emission spectrometry
- 2003
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Ingår i: Journal of Geophysical Research - Atmospheres. - 2169-897X .- 2169-8996. ; 108:D23
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Tidskriftsartikel (refereegranskat)abstract
- The functionality and characteristics of six different data processors (i.e., retrieval codes in their actual software and hardware environment) for analysis of high-resolution limb emission infrared spectra recorded by the space-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) have been validated by means of a blind test retrieval experiment based on synthetic spectra. For this purpose a self-consistent set of atmospheric state parameters, including pressure, temperature, vibrational temperatures, and abundances of trace gases and aerosols, has been generated and used as input for radiative transfer calculations for MIPAS measurement geometry and configuration. These spectra were convolved with the MIPAS field of view, spectrally degraded by the MIPAS instrument line shape, and, finally, superimposed with synthetic measurement noise. These synthetic MIPAS measurements were distributed among the participants of the project “Advanced MIPAS level-2 data analysis” (AMIL2DA), who performed temperature and species abundance profile retrievals by inverse radiative transfer calculations. While the retrieved profiles of atmospheric state parameters reflect some characteristics of the individual data processors, it was shown that all the data processors under investigation are capable of producing reliable results in the sense that deviations of retrieved results from the reference profiles are within the margin that is consistent with analytical error estimation.
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