813 research outputs found
Linked cyclopentadienyl-amide complexes of divalent, trivalent, and tetravalent vanadium: A vanadium "constrained geometry catalyst":A Vanadium “Constrained Geometry Catalyst”
Vanadium (β-(Dimethylamino)ethyl)cyclopentadienyl Complexes with Diphenylacetylene Ligands
Reduction of the V(III) (β-(dimethylamino)ethyl)cyclopentadienyl dichloride complex [η5:η1-C5H4(CH2)2NMe2]VCl2(PMe3) with 1 equiv of Na/Hg yielded the V(II) dimer {[η5:η1-C5H4(CH2)2NMe2]V(µ-Cl)}2 (2). This compound reacted with diphenylacetylene in THF to give the V(II) alkyne adduct [η5:η1-C5H4(CH2)2NMe2]VCl(η2-PhC≡CPh). Further reduction of 2 with Mg in the presence of diphenylacetylene resulted in oxidative coupling of two diphenylacetylene groups to yield the diamagnetic, formally V(V), bent metallacyclopentatriene complex [η5:η1-C5H4(CH2)2NMe2]V(C4Ph4).
Dealing with Phrase Level Co-Articulation (PLC) in speech recognition: A first approach
Whereas nowadays within-word co-articulation effects are usually sufficiently dealt with in automatic speech recognition, this is not always the case with phrase level co-articulation effects (PLC). This paper describes a first approach in dealing with phrase level co-articulation by applying these rules on the reference transcripts used for training our recogniser and by adding a set of temporary PLC phones that later on will be mapped on the original phones. In fact we temporarily break down acoustic context into a general and a PLC context. With this method, more robust models could be trained because phones that are confused due to PLC effects like for example /v/-/f/ and /z/-/s/, receive their own models. A first attempt to apply this method is described
A highly efficient titanium-based olefin polymerisation catalyst with a monoanionic iminoimidazolidide pi-donor ancillary ligand
The titanium complex Cp[1,3-(2',6' Me2C6H3) (2)(CH2N)(2)C=N] Ti(CH2Ph)(2), with a monoanionic eta(1)-iminoimidazolidide ancillary ligand, is shown to be a highly efficient catalyst for olefin polymerisation when activated with the Lewis acid B(C6F5)(3)
Novel zwitterionic diallylzirconium complexes: Synthesis, structure, polymerization activity, and deactivation pathways
Proliferation-dependent differential regulation of the dolichol pathway genes in Saccharomyces cerevisiae
The dolichol pathway serves in the synthesis of the dolichol-linked oligosaccharide precursor for protein N-glycosylation. Recently, we reported that mRNAs of genes that function at the early steps in the dolichol pathway in yeast, ALG7, ALG1 and ALG2, were co-ordinately induced following growth stimulation of G0-arrested cells in a manner similar to that of the transcripts of the early growth response genes (Kukuruzinska,M.A. and Lennon,K. Glycobiology, 4, 437-443, 1994). To determine whether the entire dolichol pathway was co-ordinately regulated with growth, we examined the expression of genes functioning late in the pathway, including two genes encoding oligosaccharyltransferase subunits, at two critical control points in the G1 phase of cell cycle: G0/G1 and START. We show that early in G1, at the G0/G1 transition point, the late ALG genes and the two oligosaccharyltransferase-encoding genes examined were regulated co-ordinately with the early ALG genes: they were downregulated upon exit from the mitotic cell cycle into G0, and they were induced following growth stimulation in the absence of de novo protein synthesis. All the dolichol pathway genes produced transcripts with short, half-lives that were rapidly stabilized in the presence of cycloheximide. In contrast, cell division arrest late in G1, at START, was accompanied by a selective downregulation of only the first dolichol pathway gene, ALG7, and not of the genes functioning later in the pathway. These results indicate that, depending on their position in G1, cells either co-ordinately or differentially regulate the dolichol pathway gene
Creating a Language Archive of Insular South East Asia and West New Guinea
The geographical region of Insular South East Asia and New Guinea is well-known as an area of mega-biodiversity. Less well-known is the extreme linguistic diversity in this area: over a quarter of the world’s 6,000 languages are spoken here. As small minority languages, most of them will cease to be spoken in the coming few generations. The project described here ensures the preservation of unique records of languages and the cultures encapsulated by them in the region. The language resources were gathered by twenty linguists at, or in collaboration with, Dutch universities over the last 40 years, and were compiled and archived in collaboration with The Language Archive (TLA) at the Max Planck Institute in Nijmegen. The resulting archive constitutes a collection ofmultimediamaterials and written documents from 48 languages in Insular South East Asia and West New Guinea. At TLA, the data was archived according to state-of-the-art standards (TLA holds the Data Seal of Approval): the component metadata infrastructure CMDI was used; all metadata categories as well as relevant units of annotation were linked to the ISO data category registry ISOcat. This guaranteed proper integration of the language resources into the CLARIN framework. Through the archive, future speaker communities and researchers will be able to extensively search thematerials for answers to their own questions, even if they do not themselves know the language, and even if the language dies
Extrinsic and intrinsic controls of zooplankton diversity in lakes
Pelagic crustacean zooplankton were collected from 336 Norwegian lakes covering a wide range of latitude, altitude, lake area, mean depth, production (as chlorophyll a), and fish community structure. Mean zooplankton species richness during the ice-free season was generally low at high latitudes and altitudes. Further, lower species richness was recorded in western lakes, possibly reflecting constraints on migration and dispersal. However, despite obvious spatial limitations, geographic boundaries were only weak predictors of mean zooplankton richness. Similarly, lake surface area did not contribute positively to mean richness such as seen in other ecosystem surveys. Rather, intrinsic factors such as primary production and fish community (planktivore) structure were identified by regression analysis as the major predictors of zooplankton diversity, while a positive correlation was observed between species richness and total zooplankton biomass. However, in spite of a large number of variables included in this study, the predictive power of multiple regression models was modest (<50% variance explained), pointing to a major role for within-lake properties, as yet unidentified intrinsic forces, stochasticity, or dispersal as constraints on zooplankton diversity in these lakes
An Amidinate Ligand with a Pendant Amine Functionality; Synthesis of a Vanadium(III) Complex and Ethene Polymerization Catalysis[#]
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