963 resultados para Omni-Lie Algebras
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An interactive software facility for designing multivariable control systems is described. The paper discusses the desirable characteristics of such a facility, the particular capabilities of CLADP and the numerical algorithms which lie behind them.
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Lake Albert and Albert Nile are a major source of fisheries resources sustaining the riparian communities in Uganda and the Democratic Republic of Congo (DRC). Like all shared bodies of Uganda Lake Albert and Albert Nile fisheries are faced with immense exploitation pressure one time described as the tragedy of the commons. In Uganda, the lake is shared by five riparian districts namely: Buliisa, Bundibugyo, Hoima, Kibaale and Nebbi. The lake covers a total estimated surface area of 5,270 square kilometers with approximately 60% within Ugandan waters. It is located in the western part of the great rift-valley at an altitude of 618 m above Sea level. The central parts of the lake are characterized by steep escarpments whereas the northern and southern parts lie in a plain of the rift valley. The plains are gently sloping, resulting in shallow swampy inshore waters in many places. The major inflowing rivers are the Semliki and Kafu in the south, and the Victoria Nile at the northern tip. The lake has a diverse fish fauna with a gradient of multi-species fisheries in different parts of the lake. The overall objective of the Frame Survey was to provide information on the facilities and services at landing sites and the composition, magnitude and distribution of fishing effort to guide development and management of the fisheries resources of Lake Albert and Albert Nile. The specific objectives were to provide information on: a) The number of fish landing sites; b) The facilities available at the fish landing sites to service the sector including accessibility; c) The service providers especially fisheries staff at fish landing sites; d) The number of fishers; e) The number and types of fishing crafts and their mode of propulsion; f) The number, types and sizes of fishing gears used on the lake and their mode of operation.
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Model-based optical motion capture systems require knowledge of the position of the markers relative to the underlying skeleton, the lengths of the skeleton's limbs, and which limb each marker is attached to. These model parameters are typically assumed and entered into the system manually, although techniques exist for calculating some of them, such as the position of the markers relative to the skeleton's joints. We present a fully automatic procedure for determining these model parameters. It tracks the 2D positions of the markers on the cameras' image planes and determines which markers lie on each limb before calculating the position of the underlying skeleton. The only assumption is that the skeleton consists of rigid limbs connected with ball joints. The proposed system is demonstrated on a number of real data examples and is shown to calculate good estimates of the model parameters in each. © 2004 Elsevier B.V. All rights reserved.
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The nature of the relationship between information technology (IT) and organizations has been a long-standing debate in the Information Systems literature. Does IT shape organizations, or do people in organisations control how IT is used? To formulate the question a little differently: does agency (the capacity to make a difference) lie predominantly with machines (computer systems) or humans (organisational actors)? Many proposals for a middle way between the extremes of technological and social determinism have been put advanced; in recent years researchers oriented towards social theories have focused on structuration theory and (lately) actor network theory. These two theories, however, adopt different and incompatible views of agency. Thus, structuration theory sees agency as exclusively a property of humans, whereas the principle of general symmetry in actor network theory implies that machines may also be agents. Drawing on critiques of both structuration theory and actor network theory, this paper develops a theoretical account of the interaction between human and machine agency: the double dance of agency. The account seeks to contribute to theorisation of the relationship between technology and organisation by recognizing both the different character of human and machine agency, and the emergent properties of their interplay.
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A polymerase chain reaction-based restriction fragment length polymorphism (RFLP) approach is used to examine Sarcocystis cruzi-like taxa from the atypical intermediate host, water buffalo, in Yunnan, People's Republic of China. The loci examined lie with
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Three new nortriterpenoids, schigrandilactones A-C (1-3), along with eight known compounds, were isolated from an organic solvent extract of Schisandra grandiflora. Compounds I and 2 feature a spirocyclic moiety in their structures, and compound 3 was cha
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Schilancidilactones A (1) and B (2). two novel tetranortriterpenoids possessing an unprecedented skeleton, have been isolated from the stems of Schisandra lancifolia. Their structures were elucidated on the basis of extensive spectroscopic analysis. The r
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Fourteen new lignans, tiegusanins A-N (1-14), together with 13 known compounds were isolated from the aerial parts of Schisandra propinqua var. sinensis. The structures and absolute configurations of 1-13 were established using a combination of spectrosco
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Twelve new dibenzocyclooctadiene lignans, marlignans A-L (1-12), together with 16 known compounds, were isolated from the leaves and stems of Schisandra wilsoniana. The structures of 1-12 were elucidated by spectroscopic methods including 1D- and 2D-NMR techniques. Compounds 1-12 were evaluated for their anti-HIV activities, of which compounds 3, 6, 8, and 12 showed modest activities with therapeutic index values of 13.2, 15.6, 17.6, and 16.4, respectively.
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A new nortriterpenoid, 20-hydroxymicrandilactone D (1) and a novel lignan glycoside, lancilignanside A (2) were isolated from leaves and stems of Schisandra lancifolia, together with three known nortriterpenoids (3-5) and nine known phenolics (6-14). The structures of new compounds 1 and 2 were determined by detailed analysis of their 1D and 2D NMR spectra, and chemical evidences. In addition, compounds 1-2, 6-7, and 9-11 showed anti-human immunodeficiency virus (HIV)-1 activities with 50% effective concentration (EC50) in the range of 3.0-99.0 mu g/ml. Compound 12 was not bioactive in this assay with EC50 more than 200 mu g/ml.
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This study investigated the 70% aqueous acetone extract of the fruits of Schisandra rubriflora which led to the isolation of eight lignans, including a new isolate, rubrisandrin C (1), and seven known lignans (2-8). The structure of 1 was established by extensive 1D and 2D NMR spectroscopy and its absolute stereochemistry was determined by CD spectrum. Compounds 1-5 and 7-8 were evaluated for their anti-HIV-1 activity that showed inhibitory activity on HIV-1(IIIB) induced syncytium formation with EC50 values in the range of 2.26 similar to 20.4 mu g/mL. Compounds 1 and 7 exerted their obvious protection of HIV-1(IIIB) inducted MT-4 host cells lytic effects with a selectivity index of 15.4 and 24.6, respectively.
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Three new dibenzocyclooctadiene lignans, schilancifolignans A-C (1-3), together with thirteen known ones, were isolated from the leaves and stems of Schisandru lancifolia. The structures of 1-3 were elucidated by spectroscopic methods, including extensive 1D- and 2D-NMR techniques. Compounds 1-3 were tested for their anti-human immunodeficiency virus-1 activities and showed weak bioactivities.
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Six new nortriterpenoids, schirubridilactones A-F (1-6). as well as 14 known compounds, were isolated from the leaves and stems of Schisandra rubriflora. The Structures of 1-6 were elucidated oil the basis of spectroscopic methods including HSQC, HMBC, H-1-H-1 COSY, and ROESY NMR experiments. The relative stereochemistry of I was confirmed through single-crystal X-ray analysis. In addition, compounds 1-6 showed anti-HIV-1 activity with EC50 values in the range 14.3-80.8 mu g/mL and Selectivity indices in the range 2.2-9.0.
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Three new dibenzocyclooctadiene lignans, wilsonilignans A-C (1-3), together with nine known ones, were isolated from the fruits of Schisandra wilsoniana. The structures of 1-3 were elucidated by spectroscopic methods including extensive 1D and 2D NMR techniques. Compounds 1-3 were also evaluated for their anti-HIV-1 activities and showed bioactivity with EC50 values of 3.26, 6.18, and 2.87g/ml, respectively.
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Giaridia lamblia was long considered to be one of the most primitive eukaryotes and to lie close to the transition between prokaryotes and eukaryotes, but several supporting features, such as lack of mitochondrion and Golgi, have been challenged recently. It was also reported previously that G. lamblia lacked nucleolus, which is the site of pre-rRNA processing and ribosomal assembling in the other eukaryotic cells. Here, we report the identification of the yeast homolog gene, krr1, in the anucleolate eukaryote, G. lamblia. The krr1 gene, encoding one of the pre-rRNA processing proteins in yeast, is actively transcribed in G. lamblia. The deduced protein sequence of G. lamblia krr1 is highly similar to yeast KRR1p that contains a single-KH domain. Our database searches indicated that krr1 genes actually present in diverse eukaryotes and also seem to present in Archaea. However, only the eukaryotic homologs, including that of G. lamblia, have the single-KH domain, which contains the conserved motif KR(K)R. Fibrillarin, another important pre-rRNA processing protein has also been identified previously in G. lamblia. Moreover, our database search shows that nearly half of the other nucleolus-localized protein genes of eukaryotic cells also have their homologs in Giardia. Therefore, we suggest that a common mechanism of pre-RNA processing may operate in the anucleolate eukaryote G. lamblia and in the other eukaryotes and that like the case of "lack of mitochondrion," "lack of nucleolus" may not be a primitive feature, but a secondarily evolutionary condition of the parasite.