377 research outputs found

    S-adenosyl-l-methionine: (S) -7,8,13, 14-tetrahydroberberine--n-methyltransferase, a branch point enzyme in the biosynthesis of benzophenanthridine and protopine alkaloids.

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    The enzyme which transfers the CH3-group of S-adenosylmethionine to the nitrogen atom of (S)-tetrahydroberberine and (S)-stylopine is found to occur in a number of plant cell cultures originating from species containing alkaloids; it is located at an important branch point in isoquinoline alkaloid biosynthesis

    The changing role of the exchange rate in a globalised economy.

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    In addition to its direct effects on the global trading and production structure, the ongoing process of globalisation may have important implications for the interaction of exchange rates and the overall economy. This paper presents evidence regarding possible changes in the role of exchange rates in a more globalised economy. First, it analyses the link between exchange rates and prices, showing that there is at most a moderate decline in exchange rate pass-through for the euro area. Next, it turns to the effect of exchange rate changes on trade flows. The findings indicate that the responsiveness of euro area exports to exchange rate changes may have declined somewhat as a result of globalisation, reflecting mainly shifts in the geographical and sectoral composition of trade flows. The paper also provides a firm-level analysis of the impact of exchange rate changes on corporate profits, which suggests that overall this relationship appears to be relatively stable over time, although there are important crosscountry differences. In addition, it studies the overall impact of exchange rates on GDP and the potential role of valuation effects as a transmission channel in the case of the euro area. JEL Classification: E3, F15, F31.Globalisation, exchange rate, trade exchange rate pass-through, valuation effects.

    S-adenosyl-L-methionine: (S)-scoulerine 9-O-methyltransferase, a highly stereo- and regio-specific enzyme in tetrahydroprotoberberine biosynthesis

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    Suspension cultures of Berberis species are useful sources for the detection and isolation of a new enzyme which transfers the methyl group from S-adenosyl-L-methionine specifically to the 9-position of the (S)-enantiomer of scoulerine, producing (S)-tetrahydrocolumbamine. The enzyme was enriched 27-fold; it is not particle bound, has a pH optimum of 8.9, a molecular weight of 63 000 and shows a high degree of substrate specificity

    Valence and magnetic instabilities in Sm compounds at high pressures

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    We report on the study of the response to high pressures of the electronic and magnetic properties of several Sm-based compounds, which span at ambient pressure the whole range of stable charge states between the divalent and the trivalent. Our nuclear forward scattering of synchrotron radiation and specific heat investigations show that in both golden SmS and SmB6 the pressure-induced insulator to metal transitions (at 2 and about 4-7 GPa, respectively) are associated with the onset of long-range magnetic order, stable up to at least 19 and 26 GPa, respectively. This long-range magnetic order, which is characteristic of Sm(3+), appears already for a Sm valence near 2.7. Contrary to these compounds, metallic Sm, which is trivalent at ambient pressure, undergoes a series of pressure-induced structural phase transitions which are associated with a progressive decrease of the ordered 4f moment.Comment: 15 pages (including 7 figures) submitted to J. Phys.: Condens. Matte

    Double-spiral magnetic structure of the Fe/Cr multilayer revealed by nuclear resonance scattering

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    We have studied the magnetization depth profiles in a [57Fe(dFe)/Cr(dCr)]x30 multilayer with ultrathin Fe layers and nominal thickness of the chromium spacers dCr 2.0 nm using nuclear resonance scattering of synchrotron radiation. The presence of a broad pure-magnetic half-order (1/2) Bragg reflection has been detected at zero external field. The joint fit of the reflectivity curves and Mossbauer spectra of reflectivity measured near the critical angle and at the "magnetic" peak reveals that the magnetic structure of the multilayer is formed by two spirals, one in the odd and another one in the even iron layers, with the opposite signs of rotation. The double-spiral structure starts from the surface with the almost antiferromagnetic alignment of the adjacent Fe layers. The rotation of the two spirals leads to nearly ferromagnetic alignment of the two magnetic subsystems at some depth, where the sudden turn of the magnetic vectors by ~180 deg (spin-flop) appears, and both spirals start to rotate in opposite directions. The observation of this unusual double-spiral magnetic structure suggests that the unique properties of giant magneto-resistance devices can be further tailored using ultrathin magnetic layers.Comment: 9 pages, 3 figure

    Worcester Public Art for ESL Students

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    Funded by the Steinbrecher Fellowship, Worcester Public Art for ESL Students are original teaching materials (a 28-page booklet and worksheets) that utilize simple English to introduce some of Worcester\u27s iconic public artworks. While the intended audience is English learners, the focus is on the content and is encouraged for use by anyone looking to enjoy and learn about Worcester history and art. The booklet includes descriptions and histories of six Worcester artworks (Burnside Fountain, Soldiers\u27 Monument, Major Taylor Statue, Mechanics Hall Mural, Rogers-Kennedy Memorial, and Chamberlain Fountain) with technical terms or difficult words bolded and explained in a glossary. Eleanor Rueffer does literacy volunteering in Worcester through the Literacy Volunteers of Greater Worcester (LVGW) and noticed a lack of relevant materials geared toward adults. She wanted to make something that both learners and educators alike could use. All photographs were taken by Eleanor Rueffer. The primary downloadable file is the booklet. The supplementary file contains the practice questions

    Laser Spectroscopy of Niobium Fission Fragments: First Use of Optical Pumping in an Ion Beam Cooler Buncher

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    A new method of optical pumping in an ion beam cooler buncher has been developed to selectively enhance ionic metastable state populations. The technique permits the study of elements previously inaccessible to laser spectroscopy and has been applied here to the study of Nb. Model independent mean-square charge radii and nuclear moments have been studied for 90,90m,91,91m,92,93,99,101,103^{90,90 m,91,91 m,92,93,99,101,103}Nb to cover the region of the N=50 shell closure and N≈60 sudden onset of deformation. The increase in mean-square charge radius is observed to be less than that for Y, with a substantial degree of β softness observed before and after N=60

    Gas chromatography vs. quantum cascade laser-based N<sub>2</sub>O flux measurements using a novel chamber design

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    Recent advances in laser spectrometry offer new opportunities to investigate the soil–atmosphere exchange of nitrous oxide. During two field campaigns conducted at a grassland site and a willow field, we tested the performance of a quantum cascade laser (QCL) connected to a newly developed automated chamber system against a conventional gas chromatography (GC) approach using the same chambers plus an automated gas sampling unit with septum capped vials and subsequent laboratory GC analysis. Through its high precision and time resolution, data of the QCL system were used for quantifying the commonly observed nonlinearity in concentration changes during chamber deployment, making the calculation of exchange fluxes more accurate by the application of exponential models. As expected, the curvature values in the concentration increase was higher during long (60 min) chamber closure times and under high-flux conditions (FN2O &gt; 150 µg N m−2 h−1) than those values that were found when chambers were closed for only 10 min and/or when fluxes were in a typical range of 2 to 50 µg N m−2 h−1. Extremely low standard errors of fluxes, i.e., from  ∼  0.2 to 1.7 % of the flux value, were observed regardless of linear or exponential flux calculation when using QCL data. Thus, we recommend reducing chamber closure times to a maximum of 10 min when a fast-response analyzer is available and this type of chamber system is used to keep soil disturbance low and conditions around the chamber plot as natural as possible. Further, applying linear regression to a 3 min data window with rejecting the first 2 min after closure and a sampling time of every 5 s proved to be sufficient for robust flux determination while ensuring that standard errors of N2O fluxes were still on a relatively low level. Despite low signal-to-noise ratios, GC was still found to be a useful method to determine the mean the soil–atmosphere exchange of N2O on longer timescales during specific campaigns. Intriguingly, the consistency between GC and QCL-based campaign averages was better under low than under high N2O efflux conditions, although single flux values were highly scattered during the low efflux campaign. Furthermore, the QCL technology provides a useful tool to accurately investigate the highly debated topic of diurnal courses of N2O fluxes and its controlling factors. Our new chamber design protects the measurement spot from unintended shading and minimizes disturbance of throughfall, thereby complying with high quality requirements of long-term observation studies and research infrastructures

    Bildungshomogamie im internationalen Vergleich: empirische Untersuchungen für die USA, Österreich, Ungarn und Deutschland

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    'Bei dem vorliegenden Beitrag handelt es sich um eine international vergleichende Analyse zur Bildungshomogamie. Untersucht werden die Länder USA, Österreich, Ungarn und Deutschland. Dabei wird auf die Daten des International Social Survey Programme (ISSP) zurückgegriffen. Im Beitrag wird analysiert, inwieweit Randverteilungseinflüsse und institutionelle Rahmenbedingungen zur Entstehung von Bildungshomogamie beitragen. Des weiteren wird überprüft, ob es sich bei bildungsbezogenen Heiratsbarrieren eher um sozialisations- oder statusbedingte Heiratsbarrieren handelt. Ausserdem wird auf verschiedene Formen sozialer Abgrenzung zwischen den Bildungsgruppen eingegangen. Die Analyse zeigt, dass die Unterschiede der Bildungshomogamie in den untersuchten Ländern vorwiegend durch Randverteilungseffekte zustande kommt. Die relative Bedeutung von Sozialisations- und Statuseffekten divergiert kaum zwischen den vier untersuchten Ländern. Dies weist auf die Existenz eines länderübergreifenden 'sozialen' Mechanismus hin, der unanhängig von institutionellen Rahmenbedingungen und länderspezifischen Vorgaben wirksam wird.' (Autorenreferat
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