The effect of flooding on the exchange of the volatile C₂-compounds ethanol, acetaldehyde and acetic acid between leaves of Amazonian floodplain tree species and the atmosphere

The effect of root inundation on the leaf emissions of ethanol, acetaldehyde and acetic acid in relation to assimilation and transpiration was investigated with 2–3 years old tree seedlings of four Amazonian floodplain species by applying dynamic cuvette systems under greenhouse conditions. Emissions were monitored over a period of several days of inundation using a combination of Proton Transfer Reaction Mass Spectrometry (PTR-MS) and conventional techniques (HPLC, ion chromatography). Under non-flooded conditions, none of the species exhibited measurable emissions of any of the compounds, but rather low deposition of acetaldehyde and acetic acid was observed instead. Tree species specific variations in deposition velocities were largely due to variations in stomatal conductance. Flooding of the roots resulted in leaf emissions of ethanol and acetaldehyde by all species, while emissions of acetic acid were only observed from the species exhibiting the highest ethanol and acetaldehyde emission rates. All three compounds showed a similar diurnal emission profile, each displaying an emission burst in the morning, followed by a decline in the evening. This concurrent behavior supports the conclusion, that all three compounds emitted by the leaves are derived from ethanol produced in the roots by alcoholic fermentation, transported to the leaves with the transpiration stream and finally partly converted to acetaldehyde and acetic acid by enzymatic processes. Co-emissions and peaking in the early morning suggest that root ethanol, after transportation with the transpiration stream to the leaves and enzymatic oxidation to acetaldehyde and acetate, is the metabolic precursor for all compounds emitted, though we can not totally exclude other production pathways. Emission rates substantially varied among tree species, with maxima differing by up to two orders of magnitude (25–1700 nmol m−2 min−1 for ethanol and 5–500 nmol m−2 min−1 for acetaldehyde). Acetic acid emissions reached 12 nmol m−2 min−1. The observed differences in emission rates between the tree species are discussed with respect to their root adaptive strategies to tolerate long term flooding, providing an indirect line of evidence that the root ethanol production is a major factor determining the foliar emissions. Species which develop morphological root structures allowing for enhanced root aeration produced less ethanol and showed much lower emissions compared to species which lack gas transporting systems, and respond to flooding with substantially enhanced fermentation rates and a non-trivial loss of carbon to the atmosphere. The pronounced differences in the relative emissions of ethanol to acetaldehyde and acetic acid between the tree species indicate that not only the ethanol production in the roots but also the metabolic conversion in the leaf is an important factor determining the release of these compounds to the atmosphere

Weyl-van-der-Waerden formalism for helicity amplitudes of massive particles

The Weyl-van-der-Waerden spinor technique for calculating helicity amplitudes of massive and massless particles is presented in a form that is particularly well suited to a direct implementation in computer algebra. Moreover, we explain how to exploit discrete symmetries and how to avoid unphysical poles in amplitudes in practice. The efficiency of the formalism is demonstrated by giving explicit compact results for the helicity amplitudes of the processes gamma gamma -> f fbar, f fbar -> gamma gamma gamma, mu^- mu^+ -> f fbar gamma.Comment: 24 pages, late

New insights in the global cycle of acetonitrile: release from the ocean and acetonitrile: release from the ocean and Venezuela

International audienceCUsing the proton transfer reaction mass spectrometry (PTR-MS) technique, acetonitrile was measured during the wet season in a Venezuelan woodland savanna. The site was located downwind of the Caribbean Sea and no biomass burning events were observed in the region. High boundary layer concentrations of 211 ±36 pmol/mol (median, ± standard deviation) were observed during daytime in the well mixed boundary layer, which is about 60 pmol/mol above background concentrations recently measured over the Mediterranean Sea and the Pacific Ocean. Most likely acetonitrile is released from the warm waters of the Caribbean Sea thereby enhancing mixing ratios over Venezuela. Acetonitrile concentrations will probably still be much higher in biomass burning plumes, however, the general suitability of acetonitrile as a biomass burning marker should be treated with care. During nights, acetonitrile dropped to levels typically around 120 pmol/mol, which is consistent with a dry deposition velocity of ~0.14 cm/s when a nocturnal boundary layer height of 100 m is assumed

Addendum to: Search for anomalous top-gluon couplings at LHC revisited

In our latest paper "Search for anomalous top-gluon couplings at LHC revisited" in Eur. Phys. J. C65 (2010), 127-135 (arXiv:0910.3049 [hep-ph]), we studied possible effects of nonstandard top-gluon couplings through the chromoelectric and chromomagnetic moments of the top quark using the total cross section of ppbar/pp --> ttbar X at Tevatron/LHC. There we pointed out that LHC data could give a stronger constraint on those two parameters, which would be hard to obtain from Tevatron data alone. We show here the first CMS measurement of this cross section actually makes it possible.Comment: 5 pages, 1 figure, LaTeX2e, Final version (to appear in Eur. Phys. C

DESING METHOD IN TRACING KNOWN DESIGN: KEKETUSAN BALINESE ORNAMENTATION

Abstract. There are three different categories of ornamentation in Ba- linese traditional building, keketusan, pepatran, and kekarangan, all used as decorative patterns for centuries and is a cultural legacy. This study focuses on the Keketusan group of patterns, and concentrates on analysis of four patterns under keketusan group: kakul-kakulan, kup- ing guling, mas-masan, and batun timun. This study borrows the prin- ciple of symmetry analysis and shape grammar, in an attempt to sys- tematically define the cultural legacy present in the keketusan pattern. A chart developed by Washburn and Crowe is used to define sym- metry principle and then is used to determine the shape grammar of a pattern that consists of initial shape and spatial relations or rules. Keywords. Shape grammar; keketusan; symmetry analysis; initial shape; rule

Improved Phase Space Treatment of Massive Multi-Particle Final States

In this paper the revised Kajantie-Byckling approach and improved phase space sampling techniques for the massive multi-particle final states are presented. The application of the developed procedures to the processes representative for LHC physics indicates the possibility of a substantial simplification of multi-particle phase space sampling while retaining a respectable weight variance reduction and unweighing efficiencies in the event generation process.Comment: Minor stilistic changes, submitted to EPJ

INDUCED GROUP AND SYMMETRY GROUP THEORY: GENERATING NEW DESIGNS FROM KNOWN ONES

Abstract. Symmetry Group theory has been extensively used to ana- lyse pattern design not only in a design field but also in other fields, such as art history and anthropology. However, there is a rare study that focuses on how to utilize symmetry groups in generating new pattern designs from known ones. Induced group theory is an expansion from Symmetry Group theory that can be used to create constructive patterns. This paper shows how to incorporate both theories in generating new design patterns along with a designated design unit. This study will pro- vide a new idea on how to incorporate theories of pattern analysis into a practice of generating new pattern designs. Keywords: Pattern; symmetry group; induced group; generative de- sign; design uni

Multiphoton Production at High Energies in the Standard Model I

We examine multiphoton production in the electroweak sector of the Standard Model in the high energy limit using the equivalence theorem in combination with spinor helicity techniques. We obtain recursion relations for currents consisting of a charged scalar, spinor, or vector line that radiates $n$ photons. Closed form solutions to these recursion relations for arbitrary $n$ are presented for the cases of like-helicity and one unlike-helicity photon production. We apply the currents singly and in pairs to obtain amplitudes for processes involving the production of $n$ photons with up to two unlike helicities from a pair of charged particles. The replacement of one or more photons by transversely polarized $$Z$-bosons is also discussed.Comment: 75 pages, CLNS 91/111

The effect of flooding on the exchange of the volatile C₂-compounds ethanol, acetaldehyde and acetic acid between leaves of Amazonian floodplain tree species and the atmosphere

International audienceThe effect of root inundation on the leaf emissions of ethanol, acetaldehyde and acetic acid was investigated with 2?3 years old tree seedlings of four Amazonian floodplain species by applying dynamic cuvette systems under greenhouse conditions. Emissions were monitored over a period of several days of inundation using a combination of Proton Transfer Reaction Mass Spectrometry (PTR-MS) and conventional techniques (HPLC, ion chromatography). Under non-flooded conditions, none of the species exhibited significant emissions of any of the compounds. A slight deposition of acetaldehyde and acetic acid was mainly observed, instead. Tree species specific variations in deposition velocities were largely due to variations in stomatal conductance. Flooding of the roots resulted in leaf emissions of ethanol and acetaldehyde by all species, while emissions of acetic acid occurred only by the species exhibiting the highest ethanol and acetaldehyde emission rates. All three compounds showed a similar diurnal emission profile, each displaying an emission burst in the morning, followed by a decline in the evening. This concurrent behavior supports the conclusion, that all three compounds emitted by the leaves are derived from ethanol produced in the roots by alcoholic fermentation, transported to the leaves with the transpiration stream and finally partly converted to acetaldehyde and acetic acid by enzymatic processes. Co-emissions and peaking in the early morning confirmed that root ethanol, after transportation with the transpiration stream to the leaves and enzymatic oxidation to acetaldehyde and acetate, is the metabolic precursor for all compounds emitted. Emission rates substantially varied among tree species, with maxima differing by up to two orders of magnitude (3?200 nmol m?2 min?1 for ethanol and 5?500 nmol m?2 min?1 for acetaldehyde). Acetic acid emissions reached 12 nmol m?2 min?1. The observed differences in emission rates between the tree species are discussed with respect to their root adaptive strategies to tolerate long term flooding, providing an indirect line of evidence that the root ethanol production is a major factor determining the foliar emissions. Species which develop morphological root structures allowing for enhanced root aeration produced less ethanol and showed much lower emissions compared to species which lack gas transporting systems, and respond to flooding with substantially enhanced fermentation rates. The pronounced differences in the relative emissions of ethanol to acetaldehyde and acetic acid between the tree species indicate that not only the ethanol production in the roots but also the metabolic conversion in the leaf is an important factor determining the release of these compounds to the atmosphere