87,026 research outputs found
Variability of blowfly head optomotor responses
No full textRosner R, Egelhaaf M, Grewe J, Warzecha A-K. Variability of blowfly head optomotor responses. Journal of Experimental Biology. 2009;212(8):1170-1184
Impact of climate variability on tropospheric ozone
No full textA simulation with the climate–chemistry model (CCM) E39/C is presented, which covers both the troposphere and stratosphere
dynamics and chemistry during the period 1960 to 1999. Although the CCM, by its nature, is not exactly representing observed
day-by-day meteorology, there is an overall model's tendency to correctly reproduce the variability pattern due to an inclusion of
realistic external forcings, like observed sea surface temperatures (e.g. El Niño), major volcanic eruption, solar cycle,
concentrations of greenhouse gases, and Quasi-Biennial Oscillation. Additionally, climate–chemistry interactions are included, like
the impact of ozone, methane, and other species on radiation and dynamics, and the impact of dynamics on emissions (lightning).
However, a number of important feedbacks are not yet included (e.g. feedbacks related to biogenic emissions and emissions due to
biomass burning). The results show a good representation of the evolution of the stratospheric ozone layer, including the ozone
hole, which plays an important role for the simulation of natural variability of tropospheric ozone. Anthropogenic NOx emissions
are included with a step-wise linear trend for each sector, but no interannual variability is included. The application of a number of
diagnostics (e.g. marked ozone tracers) allows the separation of the impact of various processes/emissions on tropospheric ozone
and shows that the simulated Northern Hemisphere tropospheric ozone budget is not only dominated by nitrogen oxide emissions
and other ozone pre-cursors, but also by changes of the stratospheric ozone budget and its flux into the troposphere, which tends to
reduce the simulated positive trend in tropospheric ozone due to emissions from industry and traffic during the late 80s and early
90s. For tropical regions the variability in ozone is dominated by variability in lightning (related to ENSO) and stratosphere–
troposphere exchange (related to Northern Hemisphere Stratospheric dynamics and solar activity). Since tropospheric background
chemistry is regarded only, the results are quantitatively limited with respect to derived trends. However, the main results are
regarded to be robust.
Although the horizontal resolution is rather coarse in comparison to regional models, such kind of simulations provide useful
and necessary information on the impact of large-scale processes and inter-annual/decadal variations on regional air quality
A trans-splicing group I intron and tRNA-hyperediting in the mitochondrial genome of the lycophyte Isoetes engelmannii
No full textGrewe F, Viehöver P, Weisshaar B, Knoop V. A trans-splicing group I intron and tRNA-hyperediting in the mitochondrial genome of the lycophyte Isoetes engelmannii. Nucleic Acids Research. 2009;37(15):5093-5104
Comparison between global models and measurements of trace gases during TROCCINOX
No full textAirborne trace gas measurements carried out over southern Brazil during TROCCINOX-1 with the Falcon aircraft are compared to results from three global models: ECHAM, MATCH and TM4. The agreement between the models, with different parameterizations for lightning-produced NOX (=NO+NO2), and the measurements is investigated along single flight tracks. A new parameterization based on the mass flux in the updrafts [Grewe et al., 2001; Kurz and Grewe, 2002] shows promising results in comparison to the more commonly used parameterization based on the cloud top height [Price and Rind, 1992]. The most realistic model results for the total amount of lightning-produced NOX on the global scale were achieved with 5 Tg(N) yr-1
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Climate Impact of a Potential Supersonic Fleet
No full textWithin the EU-project SCENIC the impact of a potential
supersonic fleet has been investigated. The methodology
how to estimate its climate impact is presented. A number
of sensitivity studies are analysed to identify options to
minimise climate impact. Since stratospheric water vapour
emissions are the most important contributor to climate
change induced by supersonics those scenarios are
minimising the climate impact which have the lowest cruise
altitude.
In order to include climate aspects in multi-disciplinary
optimisation for supersonics an assessment tool (AirClim)
has been developed within the EU Integrated Project
HISAC, which is briefly presented. The main atmospheric
input data describe the atmosphere’s sensitivity to the
emission region. Based hereon a functional relationship
has been developed between basic (supersonic) aircraft
design parameters (cruise altitude, fuel consumption) and
climate change
Genome-wide analysis of biosynthetic gene cluster reveals correlated gene loss with absence of usnic acid in lichen-forming fungi
No full textLichen-forming fungi are known to produce a large number of secondary metabolites. Some metabolites are deposited in the cortical layer of the lichen thallus where they exert important ecological functions, such as UV filtering. The fact that closely related lineages of lichen-forming fungi can differ in cortical chemistry suggests that natural product biosynthesis in lichens can evolve independent from phylogenetic constraints. Usnic acid is one of the major cortical pigments in lichens. Here we used a comparative genomic approach on 46 lichen-forming fungal species of the Lecanoromycetes to elucidate the biosynthetic gene content and evolution of the gene cluster putatively responsible for the biosynthesis of usnic acid. Whole-genome sequences were gathered from taxa belonging to different orders and families of Lecanoromycetes, where Parmeliaceae is the most well-represented taxon, and analyzed with a variety of genomic tools. The highest number of biosynthetic gene clusters was found in Evernia prunastri, Pannoparmelia angustata, and Parmotrema austrosinense, respectively, and lowest in Canoparmelia nairobiensis, Bulbothrix sensibilis, and Hypotrachyna scytodes. We found that all studied species producing usnic acid contain the putative usnic acid biosynthetic gene cluster, whereas the cluster was absent in all genomes of species lacking usnic acid. The absence of the gene cluster was supported by an additional unsuccessful search for ß-ketoacylsynthase, the most conserved domain of the gene cluster, in the genomes of species lacking usnic acid. The domain architecture of this PKS cluster-homologous to the already known usnic acid PKS cluster (MPAS) and CYT450 (MPAO)-varies within the studied species, whereas the gene arrangement is highly similar in closely related taxa. We hypothesize that the ancestor of these lichen-forming fungi contained the putative usnic acid producing PKS cluster and that the gene cluster was lost repeatedly during the evolution of these groups. Our study provides insight into the genomic adaptations to the evolutionary success of these lichen-forming fungal species and sets a baseline for further exploration of biosynthetic gene content and its evolutionary significance
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Chronique: Allemagne
No full textDagron Stéphanie, Fromont Michel, Grewe Constance, Limbach Francis, Volmerange Xavier. Allemagne. In: Annuaire international de justice constitutionnelle, 21-2005, 2006. Constitutions nationales et Constitution européenne – Autonomies locales et Constitutions. pp. 379-415
Outdoor performance of a motion-sensitive neuron in the blowfly
No full textEgelhaaf M, Grewe J, Kern R, Warzecha A-K. Outdoor performance of a motion-sensitive neuron in the blowfly. Vision research. 2001;41(27):3627-3637.We studied an identified motion-sensitive neuron of the blowfly under outdoor conditions. The neuron was stimulated by oscillating the fly in a rural environment. We analysed whether the motion-induced neuronal activity is affected by brightness changes ranging between bright sunlight and dusk, In addition, the relationship between spike rate and ambient temperature was determined. The main results are: (1) The mean spike rate elicited by visual motion is largely independent of brightness changes over several orders of magnitude as they occur as a consequence of positional changes of the sun. Even during dusk the neuron responds strongly and directionally selective to motion. (2) The neuronal spike rate is not significantly affected by short-term brightness changes caused by clouds temporarily occluding the sun. (3) In contrast, the neuronal activity is much affected by changes in ambient temperature. (C) 2001 Elsevier Science Ltd. All rights reserved
- …
