345 research outputs found
Trends in the mesopause region temperature and our present understanding-an update
No full textA comprehensive review of the long-term changes and trends in the thermal structure of the mesosphere and lower thermosphere (MLT) region has been provided by Beig et al. Beig, G., Keckhut, P., Lowe, R.P., Roble, R.G., Mlynczak, M.G., Scheer, J., Fomichev, V.I., Offermann, D., French, W.J.R., Shepherd, M.G., Semenov, A.I., Remsberg, E.E., She, C.Y., Lübken, F.J., Bremer, J., Clemesha, B.R., Stegman, J., Sigernes, F., Fadnavis, S., 2003. Review of mesospheric temperature trends. Rev. Geophys. 41 (4), 1015, doi: 10.1029/2002RG000121 in which results and analysis reported until about early 2002 were included. Since then not much new information on the temperature trends has been added. Nevertheless, some new results along with some modified results by revisiting the older data sets have been reported in recent time. Our understanding on the nature of temperature trends in the MLT region is relatively better understood now and model agreements with some of the specific observed feature are better reproduced in recent time. This paper briefly summarizes the progress made over the recent past in the field of mesopause region temperature trends and provide an update to Beig et al. (2003). Some new information is also added in recent time on the seasonal trend variability in temperature of the mesopause region which is also discussed in this article. Finally the new insight into the probable mechanisms to understand the observed trends along with future scope of the work in this field is outlined
Maria Beig : neue Heimatliteratur zwischen Nostalgie und Zuversicht
No full textThis thesis examines the semi-autobiographical work of Maria Beig in the context of traditional and contemporary regional literature. It attempts to do justice to her work as a whole. The style and content of her work are discussed with reference to topics of literary theory relating to regional literature, such as the village novella, or anti-idyllic elements, to mention only those most discussed. A further emphasis of the thesis is the question of academic reception of regional literature, in relation to the genre generally and to Maria Beig's work--that of a "poeta non docta"--in particular. Finally there is a (short) discussion of "women's issues". Such a discussion cannot be omitted, as Maria Beig is a modern woman writer whose main characters are almost exclusively feminine, and whose texts often raise questions concerned with gender.Included in the appendix are a transcript of an interview between Maria Beig and the author, and a self-written life story which Maria Beig made available to the author. These represent an indispensable aid to the reading and understanding of the thesis
Trends in the mesopause region temperature and our present understanding-an update
No full textA comprehensive review of the long-term changes and trends in the thermal structure of the mesosphere and lower thermosphere (MLT) region has been provided by Beig et al. [Beig, G., Keckhut, P., Lowe, R.P., Roble, R.G., Mlynczak, M.G., Scheer, J., Fomichev, V.I., Offermann, D., French, W.J.R., Shepherd, M.G., Semenov, A.I., Remsberg, E.E., She, C.Y., Lubken, F.J., Bremer, J., Clemesha, B.R., Stegman, J., Sigernes, F., Fadnavis, S., 2003. Review of mesospheric temperature trends. Rev. Geophys. 41 (4), 1015, doi: 10.1029/2002RG000121] in which results and analysis reported until about early 2002 were included. Since then not much new information on the temperature trends has been added. Nevertheless, some new results along with some modified results by revisiting the older data sets have been reported in recent time. Our understanding on the nature of temperature trends in the MLT region is relatively better understood now and model agreements with some of the specific observed feature are better reproduced in recent time. This paper briefly summarizes the progress made over the recent past in the field of mesopause region temperature trends and provide an update to Beig et al. (2003). Some new information is also added in recent time on the seasonal trend variability in temperature of the mesopause region which is also discussed in this article. Finally the new insight into the probable mechanisms to understand the observed trends along with future scope of the work in this field is outlined
Long-term trends in the temperature of the mesosphere/lower thermosphere region: 2. Solar response
No full textUnderstanding trends in any atmospheric quantity typically requires the ability to distinguish between naturally occurring processes that result in trends, such as the 11 year solar cycle, and potential anthropogenic secular trends that occur simultaneously. After the review of mesospheric and lower thermospheric temperature response to solar activity by Beig et al. (2008), a few new results along with some modified results by revisiting the older data sets have been reported recently. Main improvement is due to the length of data series and amount of data which have been accounted in recent years. This article summarizes the progress made in the field of temperature variability due to changing solar activity as reported recently. Recent investigations revealed that the solar signal becomes stronger with increasing latitude in the mesosphere. Temperature response to solar activity at the lower part of mesopause region is around a few degrees per 100 solar flux units (sfu), which becomes stronger (4-5 K/100 sfu) in the upper part of this region in both hemispheres. The overall global picture indicates that the solar signal in the mesopause region temperature in the Northern Hemisphere is relatively stronger in recent time in a majority of locations compared to results reported in earlier reviews
Long-term trends in the temperature of the mesosphere/lower thermosphere region: 1. Anthropogenic influences
No full textA detailed overview of long-term secular trends in temperature of the mesosphere and lower thermosphere considered to be induced by increase in greenhouse gases has been provided by Beig et al. (2003). Since then, quite a few new results have been emerged as some of the data series have become sufficiently large enough to provide results with improved confidence. Our understanding on the nature of temperature trends in the mesosphere/lower thermosphere (MLT) region is relatively better now. In the mesosphere, some of the results confirmed the earlier findings, and some new results obtained by satellite and lidar data over the tropical region have indicated a relatively weaker cooling trend as compared to the past but nevertheless strengthened the conclusion about the cooling trends. However, in the mesopause region, some of the new results now indicate a break in trend and tendency of negative signal where earlier no trend feature was noticed. This slice of no trend feature in between two cooling regimes was puzzling the modeling community, who were in search of a convincing explanation. This paper briefly outlines the progress made over the recent past in the field of MLT region secular temperature trends attributed mainly to growth of greenhouse gases near the Earth's surface
A two-dimensional model of ion composition in the stratosphere 2. Negative ions
No full textA two-dimensional meridional model of negative ions in the stratosphere is presented. It indicates that NO3 - and HSO4 - core ions with HNO3 and H2SO4 ligands are the most abundant negative ions in this region of the atmosphere. In accordance with observations at 44° N the model predicts a sharp changeover of HSO4 - core ions over NO3 - core ions at about 32 km. It also predicts a reverse changeover at 42 km above which NO3 - core ions again become dominant. For other latitudes no comparison can be made due to the lack of observational data. The negative ion composition appears to be determined by sulfuric acid vapor and nitric acid concentrations. The sensitivity of the ion composition model to the concentration of these acids is discussed. Finally, the meridional distributions of major negative ions are presented. A companion paper on positive ions is presented by Beig et al. (this issue)
Atmospheric and ionospheric response to trace gas perturbations through the ice age to the next century in the middle atmosphere. Part II - Ionization
No full textA global two-dimensional meridional ion composition model of the middle atmosphere is used to examine the effect of changing concentrations of several greenhouse gases on the overall distribution of ionization for this region, along with a steady state calculation for the upper heights. Changes in the neutral parameters for this study are taken from the companion article (Beig and Mitra, (1997). It has been predicted that there are several sensitive signals of man-made perturbations in the middle atmospheric ionization. In the mesospheric region, for a doubled CO2 scenario, we find that the total ionization density does not change appreciably and the maximum variation is found to be around 15% at about 70 km. However, the distribution of individual ions shows a considerable variation (up to about 100%) throughout the middle atmosphere. The fall-off height of the fractional abundance of water cluster ions is higher for 2050 A.D., suggesting domination of these ions up to greater heights. The concentration of water cluster ions increases below about 85 km; above this height it starts to decrease sharply with height. When a scenario with doubled CO2, with CH4 and business-as-usual (BAU) (for CFCs and N2O) is considered in the stratospheric region, it is found that only one family of negative ions, called NO3-core ions, is dominant instead of two in the normal case. Simulations are also made through the ages since the last ice age. Results indicate a reverse trend as compared to the above
Global change induced trends in ion composition of the troposphere to the lower thermosphere
No full textIn this paper a brief overview of the changes in atmospheric ion compositions driven by the human-induced changes in related neutral species, and temperature from the troposphere to lower thermosphere has been made. It is found that ionic compositions undergo significant variations. The variations calculated for the double-CO2 scenario are both long-term and permanent in nature. Major neutrals which take part in the lower and middle atmospheric ion chemical schemes and undergo significant changes due to anthropogenic activities are: O, O2, H2O, NO, acetonitrile, pyridinated compounds, acetone and aerosol. The concentration of positive ion/electron density does not change appreciably in the middle atmosphere but indicates a marginal decrease above about 75 km until about 85 km, above which the magnitude of negative trend decreases and becomes negligible at 93 km. Acetonitrile cluster ions in the upper stratosphere are likely to increase, whereas NO+ and NO+(H2O) in the mesosphere and lower thermosphere (MLT) region are expected to decrease for the double CO2 scenario. It is also found that the atmospheric density of pyridinated cluster ions is fast rising in the troposphere
Isoflurance increases cardiorespiratory coordination in rats
No full text©2008 COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.Anesthetics such as isoflurane adversely affect heart rate. In this study we analysed the interaction between heart rhythm and respiration at different concentrations of isoflurane and ventilation rates. In two rats, the electrocardiogram (ECG) and respiratory signals were recorded under the influence of isoflurane. For the assessment of cardiorespiratory coordination, we analysed the phase locking between heart rate, computed from the R-R intervals of body surface ECG, and respiratory rate, computed from impedance changes, using Hilbert transform. The changes in heart rate, percentage of synchronization and duration of synchronized epochs at different isoflurane concentrations and ventilation rates were assessed using linear regression model. From this study it appears that the amount of phase locking between cardiac and respiratory rates increases with the increase in concentration of isoflurane. Heart rate and duration of synchronized epochs increased significantly with the increase in the level of isoflurane concentration while respiratory rate was not significantly affected. Cardiorespiratory coordination also showed a considerable increase at the ventilation rates of 50- 55 cpm in both the rats, suggesting that the phase-locking between the cardiac and respiratory oscillators can be increased by breathing at a particular respiratory frequency.Muammar M. Kabir, Mirza I. Beig, Eugene Nalivaiko, Derek Abbott and Mathias Baumer
[Epitomae rerum Romanarum]
No full text[Lucius Annaeus Florus] ; [Beig. von Robertus Gaguinus: Ad lectores]Keine Titelseite. Bl. 1a leer, Textbeginn Bl. 1b: In L. Annnei Flori Epithoma de hystoria Titi Livii, argumentum foeliciter incipitImpressum gemäss ISTC/G
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