Wheat leaves emit nitrous oxide during nitrate assimilation

Nitrous oxide (N2O) is a key atmospheric greenhouse gas that contributes to global climatic change through radiative warming and depletion of stratospheric ozone. In this report, N2O flux was monitored simultaneously with photosynthetic CO2 and O2 exchanges from intact canopies of 12 wheat seedlings. The rates of N2O-N emitted ranged from <2 pmol⋅m−2⋅s−1 when NH\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{4}^{+}}}\end{equation*}\end{document} was the N source, to 25.6 ± 1.7 pmol⋅m−2⋅s−1 (mean ± SE, n = 13) when the N source was shifted to NO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{3}^{-}}}\end{equation*}\end{document}. Such fluxes are among the smallest reported for any trace gas emitted by a higher plant. Leaf N2O emissions were correlated with leaf nitrate assimilation activity, as measured by using the assimilation quotient, the ratio of CO2 assimilated to O2 evolved. 15N isotopic signatures on N2O emitted from leaves supported direct N2O production by plant NO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{3}^{-}}}\end{equation*}\end{document} assimilation and not N2O produced by microorganisms on root surfaces and emitted in the transpiration stream. In vitro production of N2O by both intact chloroplasts and nitrite reductase, but not by nitrate reductase, indicated that N2O produced by leaves occurred during photoassimilation of NO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{2}^{-}}}\end{equation*}\end{document} in the chloroplast. Given the large quantities of NO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{3}^{-}}}\end{equation*}\end{document} assimilated by plants in the terrestrial biosphere, these observations suggest that formation of N2O during NO\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{2}^{-}}}\end{equation*}\end{document} photoassimilation could be an important global biogenic N2O source.

BeF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{3}^{-}}}\end{equation*}\end{document} acts as a phosphate analog in proteins phosphorylated on aspartate: Structure of a BeF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{3}^{-}}}\end{equation*}\end{document} complex with phosphoserine phosphatase

Protein phosphoaspartate bonds play a variety of roles. In response regulator proteins of two-component signal transduction systems, phosphorylation of an aspartate residue is coupled to a change from an inactive to an active conformation. In phosphatases and mutases of the haloacid dehalogenase (HAD) superfamily, phosphoaspartate serves as an intermediate in phosphotransfer reactions, and in P-type ATPases, also members of the HAD family, it serves in the conversion of chemical energy to ion gradients. In each case, lability of the phosphoaspartate linkage has hampered a detailed study of the phosphorylated form. For response regulators, this difficulty was recently overcome with a phosphate analog, BeF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{3}^{-}}}\end{equation*}\end{document}, which yields persistent complexes with the active site aspartate of their receiver domains. We now extend the application of this analog to a HAD superfamily member by solving at 1.5-Å resolution the x-ray crystal structure of the complex of BeF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{3}^{-}}}\end{equation*}\end{document} with phosphoserine phosphatase (PSP) from Methanococcus jannaschii. The structure is comparable to that of a phosphoenzyme intermediate: BeF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{3}^{-}}}\end{equation*}\end{document} is bound to Asp-11 with the tetrahedral geometry of a phosphoryl group, is coordinated to Mg2+, and is bound to residues surrounding the active site that are conserved in the HAD superfamily. Comparison of the active sites of BeF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{3}^{-}}}\end{equation*}\end{document}⋅PSP and BeF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{3}^{-}}}\end{equation*}\end{document}⋅CeY, a receiver domain/response regulator, reveals striking similarities that provide insights into the function not only of PSP but also of P-type ATPases. Our results indicate that use of BeF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{3}^{-}}}\end{equation*}\end{document} for structural studies of proteins that form phosphoaspartate linkages will extend well beyond response regulators.

Search for signatures of magnetically-induced alignment in the arrival directions measured by the Pierre Auger Observatory

We present the results of an analysis of data recorded at the Pierre Auger Observatory in which we search for groups of directionally-aligned events (or 'multiplets') which exhibit a correlation between arrival direction and the inverse of the energy. These signatures are expected from sets of events coming from the same source after having been deflected by intervening coherent magnetic fields. The observation of several events from the same source would open the possibility to accurately reconstruct the position of the source and also measure the integral of the component of the magnetic field orthogonal to the trajectory of the cosmic rays. We describe the largest multiplets found and compute the probability that they appeared by chance from an isotropic distribution. We find no statistically significant evidence for the presence of multiplets arising from magnetic deflections in the present data. (C) 2011 Elsevier B.V. All rights reserved.

Spoken document retrieval experiments with IR-n system

This paper describes the first participation of IR-n system at Spoken Document Retrieval, focusing on the experiments we made before participation and showing the results we obtained. IR-n system is an Information Retrieval system based on passages and the recognition of sentences to define them. So, the main goal of this experiment is to adapt IR-n system to the spoken document structure by means of the utterance splitter and the overlapping passage technique allowing to match utterances and sentences.

Compositional and Geochemical Signatures for the Sedimentary Evolution of the Middle Triassic–Lower Jurassic Continental Redbeds from Western-Central Mediterranean Alpine Chains

Compositional and chemical analyses suggest that Middle Triassic–Lower Liassic continental redbeds (in the internal domains of the Betic, Maghrebian, and Apenninic chains) can be considered a regional lithosome marking the Triassic-Jurassic rift-valley stage of Tethyan rifting, which led to the Pangaea breakup and subsequent development of a mosaic of plates and microplates. Sandstones are quartzose to quartzolithic and represent a provenance of continental block and recycled orogen, made up mainly of Paleozoic metasedimentary rocks similar to those underlying the redbeds. Mudrocks display K enrichments; intense paleoweathering under a hot, episodically humid climate with a prolonged dry season; and sediment recycling. Redbeds experienced temperatures in the range of 100°–160°C and lithostatic/tectonic loading of more than 4 km. These redbeds represent an important stratigraphic signature to reconstruct a continental block (Mesomediterranean Microplate) that separated different realms of the western Tethys from Middle-Late Jurassic to Miocene, when it was completely involved in Alpine orogenesis.

The role of statistical and semantic features in single-document extractive summarization

This paper reports on the further results of the ongoing research analyzing the impact of a range of commonly used statistical and semantic features in the context of extractive text summarization. The features experimented with include word frequency, inverse sentence and term frequencies, stopwords filtering, word senses, resolved anaphora and textual entailment. The obtained results demonstrate the relative importance of each feature and the limitations of the tools available. It has been shown that the inverse sentence frequency combined with the term frequency yields almost the same results as the latter combined with stopwords filtering that in its turn proved to be a highly competitive baseline. To improve the suboptimal results of anaphora resolution, the system was extended with the second anaphora resolution module. The present paper also describes the first attempts of the internal document data representation.

Compositional signatures of the Cenozoic sedimentary succesions of the Malaguide Complex (Betic Cordillera, Spain)

The studied Cenozoic sedimentary successions consist of deposits from continental/shallow-water to deep-marine environments of the Malaguide Complex (Betic Cordillera) outcropping in the Sierra Espuña area (SE Spain). The aim of this study is to characterize the composition, source area(s) provenance and weathering processes of these sedimentary successions from the pre-orogenic (Paleocene-Early Oligocene) to the syn-orogenic (Late Oligocene-Early Miocene) stage using petrological and geochemical methodologies. The studied sandstones are mainly quartzolithic with abundant metamorphic and sedimentary lithic fragments. In particular, the composition of samples from the pre-orogenic cycle is mainly carbonate with important siliciclastic components that occur within the medium to fine grained arenites. The composition of samples from the syn-orogenic cycle is characterized by a sharp change from carbonate to siliciclastic terms. Thus, the composition of the overall sandstone samples is very heterogeneous and suggests a source area mainly characterized by the Malaguide basement and lower units of the Internal Betic Zone, that partially compose the Mesomediterranean Microplate. The geochemical proxies suggest a provenance mainly from felsic source area with a minor supply from mafic rocks in some samples of the syn-orogenic stage. Furthermore, palaeoweathering indices indicate low to moderate weathering conditions for the sources. The Cenozoic sedimentary successions of the Malaguide Complex played an important role in the geodynamic evolution of the Betic Cordillera that represents the key tectonic element of the western domains of the Mesomediterranean Microplate.

Bond of Samuel Leighton and Samuel Shapleigh to the Harvard Corporation, Aug. 23, 1785

Shapleigh and Leighton's signatures have been cut out from the bottom of this document. It was "signed, sealed and delivered" in the presence of Benjamin Stevens and Ebenezer Marriner.

Bond of Samuel Shapleigh and Thomas Adams to the Harvard Corporation, Aug. 15, 1789

Shapleigh and Adams' signatures have been cut out from the bottom of this document. It was "signed, sealed and delivered" in the presence of Thomas Gray and Darius Shaw.

Bond of Samuel Shapleigh and unknown co-signatory to the Harvard Corporation, Aug. 15, 1789

Shapleigh and the unknown co-signatory's signatures have been cut out from the bottom of this document. It was "signed, sealed and delivered" in the presence of Owen Warland and William Wahan.

The articles which all that belong to the private meeting instituted at Harvard College, 1719, assent unto, January 10, 1723

This one-page document contains the handwritten laws of an unnamed Harvard College religious society. The document is dated January 10, 1723 and includes the signatures of twenty-six students in the Harvard Classes of 1724 through 1728.