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Showing papers by "Braunschweig University of Technology published in 1997"


Journal ArticleDOI
TL;DR: Results suggest that Rho regulates actin polymerization by targeting profilin via p140mDia beneath the specific plasma membranes.
Abstract: Rho small GTPase regulates cell morphology, adhesion and cytokinesis through the actin cytoskeleton. We have identified a protein, p140mDia, as a downstream effector of Rho. It is a mammalian homolog of Drosophila diaphanous, a protein required for cytokinesis, and belongs to a family of formin-related proteins containing repetitive polyproline stretches. p140mDia binds selectively to the GTP-bound form of Rho and also binds to profilin. p140mDia, profilin and RhoA are co-localized in the spreading lamellae of cultured fibroblasts. They are also co-localized in membrane ruffles of phorbol ester-stimulated sMDCK2 cells, which extend these structures in a Rho-dependent manner. The three proteins are recruited around phagocytic cups induced by fibronectin-coated beads. Their recruitment is not induced after Rho is inactivated by microinjection of botulinum C3 exoenzyme. Overexpression of p140mDia in COS-7 cells induced homogeneous actin filament formation. These results suggest that Rho regulates actin polymerization by targeting profilin via p140mDia beneath the specific plasma membranes.

847 citations


Book ChapterDOI
TL;DR: The Cluster mission as mentioned in this paper provides a new opportunity to study plasma processes and structures in the near-Earth plasma environment using four-point measurements of the magnetic field, which can enable the analysis of the three dimensional structure and dynamics of a range of phenomena which shape the macroscopic properties of the magnetosphere.
Abstract: The Cluster mission provides a new opportunity to study plasma processes and structures in the near-Earth plasma environment Four-point measurements of the magnetic field will enable the analysis of the three dimensional structure and dynamics of a range of phenomena which shape the macroscopic properties of the magnetosphere Difference measurements of the magnetic field data will be combined to derive a range of parameters, such as the current density vector, wave vectors, and discontinuity normals and curvatures, using classical time series analysis techniques iteratively with physical models and simulation of the phenomena encountered along the Cluster orbit The control and understanding of error sources which affect the four-point measurements are integral parts of the analysis techniques to be used The flight instrumentation consists of two, tri-axial fluxgate magnetometers and an on-board data-processing unit on each spacecraft, built using a highly fault-tolerant architecture High vector sample rates (up to 67 vectors s-1) at high resolution (up to 8 pT) are combined with on-board event detection software and a burst memory to capture the signature of a range of dynamic phenomena Data-processing plans are designed to ensure rapid dissemination of magnetic-field data to underpin the collaborative analysis of magnetospheric phenomena encountered by Cluster

373 citations


Journal ArticleDOI
TL;DR: In this paper, the main sources of uncertainties involved in the analysis of structures and solids are discussed and the tools available to deal with them, as well as the techniques and methods involved in stochastic modeling.

354 citations


Journal ArticleDOI
TL;DR: Flow cytometric analysis of freshly prepared human peripheral blood lymphocytes reveals that lipoic acid acts mainly to normalize a subpopulation of cells severely compromised in thiol status rather than to increase thiol content beyond physiological levels, suggesting it may have clinical relevance in restoration of severely glutathione deficient cells.
Abstract: Lipoic acid (thiotic acid) is being used as a dietary supplement, and as a therapeutic agent, and is reported to have beneficial effects in disorders associated with oxidative stress, but its mechanism of action remains unclear. We present evidence that lipoic acid induces a substantial increase in cellular reduced glutathione in cultured human Jurkat T cells human erythrocytes, C6 glial cells, NB41A3 neuroblastoma cells, and peripheral blood lymphocytes. The effect depends on metabolic reduction of lipoic acid to dihydrolipoic acid. Dihydrolipoic acid is released into the culture medium where it reduces cystine. Cysteine thus formed is readily taken up by the neutral amino acid transport system and utilized for glutathione synthesis. By this mechanism lipoic acid enables cystine to bypass the xc- transport system, which is weakly expressed in lymphocytes and inhibited by glutamate. Thereby lipoic acid enables the key enzyme of glutathione synthesis, gamma-glutamylcysteine synthetase, which is regulated by uptake-limited cysteine supply, to work at optimum conditions. Flow cytometric analysis of freshly prepared human peripheral blood lymphocytes, using monobromobimane labeling of cellular thiols, reveals that lipoic acid acts mainly to normalize a subpopulation of cells severely compromised in thiol status rather than to increase thiol content beyond physiological levels. Hence lipoic acid may have clinical relevance in restoration of severely glutathione deficient cells.

335 citations


Journal ArticleDOI
TL;DR: It would appear that the enzymes of central carbohydrate metabolism have evolved novel targeting possibilities regardless of their origins, which suggests a new hypothesis to explain organelle genome persistence, based on the testable idea that some organelle-encoded gene products might be toxic when present in the cytosol or other inappropriate cellular compartments.
Abstract: The evolutionary histories of the 12 enzymes that catalyze the reactions of the Calvin cycle in higher-plant chloroplasts are summarized. They are shown to be encoded by a mixture of nuclear genes of cyanobacterial and proteobacterial origin. Moreover, where cytosolic isoforms of these enzymes are found they are almost invariably encoded by genes of clearly endosymbiont origin. We infer that endosymbiosis resulted in functional redundancy that was eliminated through differential gene loss, with intruding eubacterial genes repeatedly replacing pre-existing nuclear counterparts to which they were either functionally or structurally homologous. Our findings fail to support the `product-specificity corollary', which predicts re-targeting of nuclear-encoded gene products to the organelle from whose genome they originated. Rather it would appear that the enzymes of central carbohydrate metabolism have evolved novel targeting possibilities regardless of their origins. Our findings suggest a new hypothesis to explain organelle genome persistence, based on the testable idea that some organelle-encoded gene products might be toxic when present in the cytosol or other inappropriate cellular compartments.

258 citations


Journal ArticleDOI
TL;DR: Many problems arising in traffic planning can be modelled and solved using discrete optimization, and this chapter focuses on recent developments which were applied to large scale real world instances.
Abstract: Many problems arising in traffic planning can be modelled and solved using discrete optimization. We will focus on recent developments which were applied to large scale real world instances. Most railroad companies apply a hierarchically structured planning process. Starting with the definition of the underlying network used for transport one has to decide which infrastructural improvements are necessary. Usually, the rail system is periodically scheduled. A fundamental base of the schedule are the lines connecting several stations with a fixed frequency. Possible objectives for the construction of the line plan may be the minimization of the total cost or the maximization of the passengers’s comfort satisfying certain regulations. After the lines of the system are fixed, the train schedule can be determined. A criterion for the quality of a schedule is the total transit time of the passengers including the waiting time which should be minimized satisfying some operational constraints. For each trip of the schedule a train consisting of a locomotive and some carriages is needed for service. The assignment of rolling stock to schedule trips has to satisfy operational requirements. A comprehensible objective is to minimize the total cost. After all strategic and tactical planning the schedule has to be realized. Several external influences, for example delayed trains, force the dispatcher to recompute parts of the schedule on-line.

243 citations




Journal ArticleDOI
TL;DR: Heuristics for Type 1 and Type 2 of the Simple Assembly Line Balancing Problem (SALBP) are described and bidirectional and dynamic extensions to heuristic priority rules widely used for SALBP-1 and 2 are described.
Abstract: In this paper heuristics for Type 1 and Type 2 of the Simple Assembly Line Balancing Problem (SALBP) are described. Type 1 of SALBP (SALBP-1) consists of assigning tasks to work stations such that the number of stations is minimized for a given production rate whereas Type 2 (SALBP-2) is to maximize the production rate, or equivalently, to minimize the sum of idle times for a given number of stations. In both problem types, precedence constraints between the tasks have to be considered.

201 citations


Journal ArticleDOI
TL;DR: A mixed integer linear programming formulation is introduced and for real world data the model is succeeded in solving the model by means of suitable relaxations and sufficiently strong cutting planes with the commercial LP solver CPLEX 3.0.

196 citations


Proceedings ArticleDOI
13 Nov 1997
TL;DR: An approach which combines simulation and formal techniques in a safe way to improve analysis precision and tighten the timing bounds is presented, which shows an unprecedented analysis precision allowing us to reduce performance overhead for provably correct system or interface timing.
Abstract: Formal Program running time verification is an important issue in system design required for performance optimization under "first-time-right" design constraints and for real-time system verification. Simulation based approaches or simple instruction counting are not appropriate and risky for more complex architectures in particular with data dependent execution paths. Formal analysis techniques have suffered from loose timing bounds leading to significant performance penalties when strictly adhered to. We present an approach which combines simulation and formal techniques in a safe way to improve analysis precision and tighten the timing bounds. Using a set of processor parameters, it is adaptable to arbitrary processor architectures. The results show an unprecedented analysis precision allowing to reduce performance overhead for provably correct system or interface timing.

Journal ArticleDOI
TL;DR: In this paper, the angular relation of the substrate surface with respect to the incoming vapor direction in an evaporation deposition system is controlled to engineer the morphology of thin films, which can produce columnar morphologies ranging from chevron structures to continuously varied structures resembling S shapes and C shapes.
Abstract: By controlling the angular relation of the substrate surface with respect to the incoming vapor direction in an evaporation deposition system, it is possible to engineer the morphology of thin films. Sculptured nematic thin films result under low adatom mobility conditions when the substrates are rotated about an axis perpendicular to the vapor direction. Thin films of MgF2 were deposited onto room temperature substrates to produce columnar morphologies ranging from chevron structures to continuously varied structures resembling S shapes and C shapes. The specific morphologies are virtually unlimited within the restriction that the minimum angle χM of the local columnar direction with respect to the substrate plane is about 30°.

Journal ArticleDOI
TL;DR: From the CH2Cl2 extract of the temperate marine red alga, Laurencia rigida, which has antifouling properties, eight sesquiterpenes were isolated and four were shown to be new natural products.
Abstract: From the CH2Cl2 extract of the temperate marine red alga, Laurencia rigida, which has antifouling properties, eight sesquiterpenes (1−8) were isolated. Of these, four (3-acetoxy-E-γ-bisabolene (1), (−)-10α-bromo-9β-hydroxy-α-chamigrene (2), rigidol (3), and (+)-(10S)-10-bromo-β-chamigrene (4)), were shown to be new natural products. For the known compound deschloroelatol (5), reassignment of the 1H- and 13C-NMR data was found to be necessary on the basis of extensive NMR measurements. For elatol (6), complete 1H- and 13C-NMR data are also reported. The antimicrobial and antialgal activities of all isolates were assessed.

Journal ArticleDOI
TL;DR: The imager for Mars Pathfinder (IMP), a stereoscopic, multispectral camera, is described in terms of its capabilities for studying the Martian environment as mentioned in this paper, which is intended to serve as a guide to understand the scientific integrity of the IMP data that will be returned from Mars starting on July 4, 1997.
Abstract: The imager for Mars Pathfinder (IMP), a stereoscopic, multispectral camera, is described in terms of its capabilities for studying the Martian environment. The camera's two eyes, separated by 15.0 cm, provide the camera with range-finding ability. Each eye illuminates half of a single CCD detector with a field of view of 14.4×14.0° and has 12 selectable filters. The ƒ/18 optics have a large depth of field, and no focussing mechanism is required; a mechanical shutter is avoided by using the frame transfer capability of the 512×512 CCD. The resolving power of the camera, 0.98 mrad/pixel, is approximately the same as the Viking Lander cameras; however, the signal-to-noise ratio for IMP greatly exceeds Viking, approaching 350. This feature along with the stable calibration of the filters between 440 and 1000 nm distinguishes IMP from Viking. Specially designed targets are positioned on the Lander; they provide information on the magnetic properties of wind-blown dust, measure the wind vectors, and provide radiometric standard reflectors for calibration. Also, eight low-transmission filters are included for imaging the Sun directly at multiple wavelengths, giving IMP the ability to measure dust opacity and potentially the water vapor content. Several experiments beyond the requisite color panorama are described in detail: contour mapping of the local terrain, multispectral imaging of the surrounding rock and soil to study local mineralogy, viewing of three wind socks, measuring atmospheric opacity and water vapor content, and estimating the magnetic properties of wind-blown dust. This paper is intended to serve as a guide to understanding the scientific integrity of the IMP data that will be returned from Mars starting on July 4, 1997.

Journal ArticleDOI
TL;DR: The fluoride fiber laser with the longest emission wavelength, the Ho(3+)-transition at 3.9 mum in the attenuation minimum of the 3-5-mum atmospheric window, is characterized and room-temperature fluorescence and laser action with liquid-nitrogen cooling is described.
Abstract: The fluoride fiber laser with the longest emission wavelength, the Ho(3+)-transition at 3.9 mum in the attenuation minimum of the 3-5-mum atmospheric window, is characterized. After reviewing the importance of fluoride fibers due to their low phonon energies, we describe room-temperature fluorescence and laser action with liquid-nitrogen cooling. Continuous-wave laser action at 3.9 mum is presented for the 640- and the 890-nm pump ranges. A shift of the emission wavelength is achieved by varying the resonator mirrors. Laser characteristics and temperature dependence are discussed.

Journal ArticleDOI
TL;DR: Five known and three new dihydroisocoumarins were isolated from different fungi and the absolute configuration of these secondary metabolites was confirmed by CD measurements and in two cases by X-ray structure analysis.

Journal ArticleDOI
TL;DR: In this paper, the influence of mechanical cell disintegration and its influence on anaerobic digestion was investigated using four different methods, including a stirred ball mill and a high pressure homogenizer.

Journal ArticleDOI
TL;DR: The novel enzyme was named senecionine N-oxygenase (SNO), which isolated from the haemolymph of the sequestering arctiid Tyria jacobaeae and purified to electrophoretic homogeneity, and showed the same general substrate specificity but differ in their affinities towards the main structural types of pyrrolizidine alkaloids.
Abstract: Larvae of Creatonotos transiens (Lepidoptera, Arctiidae) and Zonocerus variegatus (Orthoptera, Pyr-gomorphidae) ingest 14C-labeled senecionine and its N-oxide with the same efficiency but sequester the two tracers exclusively as N-oxide. Larvae of the non-sequestering Spodoptera littoralis eliminate efficiently the ingested alkaloids. During feeding on the two alkaloidal forms transient levels of senecionine (but not of the N-oxide) are built up in the haemolymph of S. littoralis larvae. Based on these results, senecionine [18O]N-oxide was fed to C. transiens larvae and Z. variegatus adults. The senecionine N-oxide recovered from the haemolymph of the two insects shows an almost complete loss of 18O label, indicating reduction of the orally fed N-oxide in the guts, uptake of the tertiary alkaloid and its re-N-oxidation in the haemolymph. The enzyme responsible for N-oxidation is a soluble mixed function monooxygenase. It was isolated from the haemolymph of the sequestering arctiid Tyria jacobaeue and purified to electrophoretic homogeneity. The enzyme is a flavoprotein with a native M, of 200000 and a subunit M, of 51 000. It shows a pH optimum at 7.0, has its maximal activity at a temperature of 40–45°C and an isoelectric point at pH 4.9. The reaction is strictly NADPH-dependent (Km, 1.3 μM). From 20 pyrrolizidine alkaloids so far tested as substrates, the enyzme N-oxidizes only alkaloids with structural elements which are essential for hepatotoxic and genotoxic pyrrolizidine alkaloids (i.e. 1,2-double bond, esterification of the allylic hydroxyl group, presence of a second free or esterified hydroxyl group at carbon 7). A great variety of related alkaloids and xenobiotics were tested as substrate, none was accepted. The K, values of senecionine, monocrotaline and heliotrine, representing the three main types of pyrrolizidine alkaloids, are 1.3 μM, 12.5 μM and 290 μM, respectively. The novel enzyme was named senecionine N-oxygenase (SNO). The enzyme was partially purified from two other arctiids. The three SNOs show the same general substrate specificity but differ in their affinities towards the main structural types of pyrrolizidine alkaloids. The enzymes from the two generalists (Creatonotos transiens and Arctia caja) display a broader substrate affinity than the enzyme from the specialist (Tyria jacobaeae). The two molecular forms of pyrrolizidine alkaloids, the lipophilic protoxic tertiary amine and its hydrophilic nontoxic N-oxide are discussed in respect to their bioactivation and detoxification in mammals and their role as defensive chemicals in specialized insects. Pyrrolizidine-alkaloid-sequestering insects store the alkaloids as nontoxic N-oxides which are reduced in the guts of any potential insectivore. The lipophilic tertiary alkaloid is absorbed passively and then bioactivated by cytochrome P 450 oxidase.

Journal ArticleDOI
TL;DR: In this article, a new approach for the evaluation of the convolution integrals, the so-called "Operational Quadrature Methods" developed by Lubich, is presented.
Abstract: The usual time domain Boundary Element Method (BEM) contains fundamentalsolutions which are convoluted with time-dependent boundary data andintegrated over the boundary surface. Here, a new approach for theevaluation of the convolution integrals, the so-called ’OperationalQuadrature Methods‘ developed by Lubich, is presented. In thisformulation, the convolution integral is numerically approximated by aquadrature formula whose weights are determined using the Laplacetransform of the fundamental solution and a linear multisep method. Tostudy the behaviour of the method, the numerical convolution of afundamental solution with a unit step function is compared with theanalytical result. Then, a time domain Boundary Element formulationapplying the ’Operational Quadrature Methods‘ is derived. For thisformulation only the fundamental solutions in Laplace domain arenecessary. The properties of the new formulation are studied with anumerical example.

Journal ArticleDOI
TL;DR: A possible role for vinculin is proposed in organizing the distal ends of microfilaments at the plasma membrane into the point-like structure characteristic for cell-matrix contacts.
Abstract: Vinculin, a structural protein of animal cells, is critically involved in the assembly of microfilament/plasma membrane junctions at cell contacts. To understand its role in organizing the distal portions of microfilaments into specific, morphologically distinct structures at these sites in more detail, we characterized its interaction with filamentous actin and with itself by means of in vitro assays. Using recombinant proteins comprising different parts of the vinculin tail fused to the maltose-binding protein of Escherichia coli, we show in sedimentation assays that this part of vinculin harbors two discrete sites that can bind to actin independently. They reside within amino acid residues 893–985 and 1016–1066 of the 1066-residue polypeptide chain. However, both sites are necessary to cross-link or bundle actin filaments, as demonstrated by low shear viscometry. Crosslinking and bundling are alternatives determined by the molar ratio of fusion protein to F-actin. Both actin-binding sequences are capable of oligomer formation, as shown in chemical-cross-linking and dot-overlay assays. These data allow us to propose a possible role for vinculin in organizing the distal ends of microfilaments at the plasma membrane into the point-like structure characteristic for cell-matrix contacts.

Journal ArticleDOI
TL;DR: Results from the investigation of an association between increased exposure to residential extremely-low frequency elec-tromagnetic fields (ELF-EMF) and childhood leukemia may indicate a positive association between EMF andchildhood leukemia.
Abstract: The investigation of an association between increased exposure toresidential extremely-low frequency elec-tromagnetic fields (ELF-EMF) andchildhood leukemia was part of a population-based case-control study carriedout between 1992 and 1995 in the northwestern part of Germany. A total of 129children with leukemia and 328 controls participated in the EMF-study.Exposure assessment comprised measurements of the magnetic field over 24hours in the child's bedroom at the residence where the child had been livingfor the longest period before the date of diagnosis, and spot measurements atall residences where the child had been living for more than one year. Themedian of the 24h-measurement in the child's bedroom was regarded as the mostvalid exposure variable. For children exposed to more than 0.2 μT, anelevated but not significant odds ratio (OR) was observed (OR = 3.2, 95percent confidence interval = 0.7-14.9). These figures are based on only fourleukemia cases and three controls since only 1.5 percent of the studypopulation was classified as highly exposed. Exploratory analyses revealedORs that were not statistically significantly increased for othercharacteristics of the magnetic field at varying cut-points. The results arecomparable with those from other studies. Although not statisticallysignificant, they may indicate a positive association between EMF andchildhood leukemia.

Journal ArticleDOI
TL;DR: Binding studies with recombinantly expressed and purified Cnx1 and with its single domains revealed a high affinity of the G domain to MPT with equimolar binding, and the entire CnX1 showed a tight and cooperative MPT binding.

Journal ArticleDOI
TL;DR: It was concluded that both sensory and attentional or control mechanisms were responsible for global precedence and that the hemispheres differed with respect to the latter.
Abstract: There are many conditions in which identification proceeds faster for the global form of a hierarchical pattern than for its local parts. Since the global form usually contains more lower spatial frequencies than do the local forms, it has frequently been suggested that the higher transmission rate of low spatial frequencies is responsible for the global advantage. There are also functional hemispheric differences. While the right hemisphere is better at processing global information, the left hemisphere has an advantage with respect to local information. In accordance with the spatial-frequency hypothesis, it has been speculated that this difference is due to a differential capacity of the hemispheres for processing low and high spatial frequencies. To test whether low spatial frequencies were responsible for the global advantage and/or for the observed hemispheric differences, two experiments were carried out with unfiltered and highpass-filtered compound-letter stimuli presented at the left, right, or center visual field. The first experiment, in which the target level was randomized in each trial block, revealed that low spatial frequencies were not necessary for either global advantage or for hemispheric differences. Highpass filtering merely increased the response times. In the second experiment, the target level was held constant in each block. This generally increased the speed of responding and produced interactions between filtering and global-local processing. It was concluded that both sensory and attentional or control mechanisms were responsible for global precedence and that the hemispheres differed with respect to the latter.

Journal ArticleDOI
TL;DR: The time-stepping BEM procedure produces instabilities and high numerical damping, when the time step size is chosen too small and too large, respectively as discussed by the authors, when the fundamental solution is known only in the frequency domain such that the time history of a response can only be obtained by an inverse transformation of the frequencydomain results.
Abstract: The usual time domain Boundary Element Method (BEM) contains fundamental solutions which are convoluted with time-dependent boundary data and integrated over the boundary surface. If the fundamental solution is known, e.g., in Elastodynamics, the temporal convolution can be performed analytically when the boundary data are approximated by polynomial shape functions in time and in the boundary elements. This formulation is well known, but the resulting time-stepping BEM procedure produces instabilities and high numerical damping, when the time step size is chosen too small and too large, respectively. Moreover, in case of viscoelastic or poroelastic domains, the fundamental solution is known only in the frequency domain such that the time history of a response can only be obtained by an inverse transformation of the frequency domain results.

Journal ArticleDOI
TL;DR: The functional characteristics of tryparedoxin explain the limited capacity of trypanosomatids in coping with oxidative stress and qualify the enzyme as a potential target for the design of specific trypanocidal compounds.
Abstract: Tryparedoxin, a thioredoxin-related protein from Crithidia fasciculata with a molecular mass of 16 kDa catalyses the reduction of a peroxiredoxin-type peroxidase, Cf21, at the expense of trypanothione [Nogoceke, E., Gommel, D. U., Kieζ, M., Kalisz, H. M. & Flohe, L. E. (1997) Biol. Chem. Hoppe-Seyler 378, 827–8361, The kinetic analysis of tryparedoxin revealed an enzyme substitution mechanism. The corresponding molecular event was elucidated to be a reversible oxidoreduction of the disulfide bridge in the thioredoxin-related motif WCPPC. The amino-proximal cysteine residue of this active site was more reactive in S-alkylation experiments than the distal residue. The natural substrates of tryparedoxin, trypanothione and Cf21, could only be substituted by glutathione and glutathione disulfide with considerable loss in activity. The pronounced specificity of tryparedoxin is further accentuated by low limiting Km values for Cf21 and trypanothione (2.2 μM and 130 μM, respectively, as compared to 990 μM for gluthathione disulfide and an infinite value for glutathione). Tryparedoxin can therefore be classified as a trypanothione: peroxiredoxin oxidoreductase. The reduction of tryparedoxin by trypanothione appears to be the rate-limiting step in the trypanothione-dependent hydroperoxide reduction because(a) the regeneration of reduced tryparedoxin from the tryparedoxin-trypanothione complex is rate limiting (kcal, 392 min−1), (b) the physiological trypanothione concentrations may not always saturate tryparedoxin, and (c) the rate constants for the net forward reaction of Cf21 are faster than those of the tryparedoxin reaction. The functional characteristics of tryparedoxin explain the limited capacity of trypanosomatids in coping with oxidative stress and qualify the enzyme as a potential target for the design of specific trypanocidal compounds.

Journal ArticleDOI
TL;DR: In this article, the purification of three biologically pre-treated leachates was performed using three different processes: hydrogen peroxide/UV, ozone and ozone/fixed bed catalyst processes.

Journal ArticleDOI
TL;DR: The interaction among the bacteria involved and their competition for existence in the biofilm have been worked out during the transition from a heterotrophic to an auto-/heterotrophic biofilm.

Journal ArticleDOI
TL;DR: The reactions between [(PPh3)2N][Au(acac)2] (acac = acetylacetonate) reacts with terminal alkynes RC⋮CH to give [PPh 3]2N] (R = H, tBu, SiMe3, CH2X (X = Cl, Br, OH)) complexes as mentioned in this paper.

Proceedings ArticleDOI
13 Jun 1997
TL;DR: A partitioning approach thatynamically determines the partitioning granularity to adapt optimizationsteps to application properties and to intermediate optimization results is presented.
Abstract: Computer aided hardware/software partitioning is one of the keychallenges in hardware/software co-design. While previous approacheshave used a fixed granularity, i.e. the size of the partitioningobjects was fixed, we present a partitioning approach thatdynamically determines the partitioning granularity to adapt optimizationsteps to application properties and to intermediate optimizationresults. Experiments with simulated annealing optimizationshow a faster convergence and far better adaptability to costfunction variations than in previous experiments with fixed granularity.

Journal ArticleDOI
TL;DR: These estimates based upon phylogenetic analysis of protein data from complete chloroplast genomes are in much better accordance with current interpretations of fossil evidence than previous molecular estimates.
Abstract: Fifty-eight homologous protein sequences from the completely sequenced chloroplast genomes ofZea mays, Oryza sativa, Nicotiana tabacum, Pinus thunbergii, Marchantia polymorpha andPoryphyra purpurea were investigated. Analyzed individually, only 40 of the 58 proteins gave the true, known topology for these species. Trees constructed from the concatenated 14295 amino acid alignment and from automatically generated subsets of the data containing successively fewer polymorphisms were used to estimate theNicotiana-Zea andPinus-angiosperm divergence times as 160 and 348 million years, respectively, with an uncertainty of about 10%. These estimates based upon phylogenetic analysis of protein data from complete chloroplast genomes are in much better accordance with current interpretations of fossil evidence than previous molecular estimates.