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1.
We show that the wavefront approach to Voronoi diagrams (a deterministic line-sweep algorithm that does not use geometric
transform) can be generalized to distance measures more general than the Euclidean metric. In fact, we provide the first worst-case
optimal (O (n logn) time,O(n) space) algorithm that is valid for the full class of what has been callednice metrics in the plane. This also solves the previously open problem of providing anO (nlogn)-time plane-sweep algorithm for arbitraryL
k
-metrics. Nice metrics include all convex distance functions but also distance measures like the Moscow metric, and composed
metrics. The algorithm is conceptually simple, but it copes with all possible deformations of the diagram.
Research partially supported by the Natural Sciences and Engineering Research Council of Canada.
Research partially supported by the Deutsche Forschungsgemeinschaft, Grant No. Kl 655/2-1. 相似文献
2.
In this paper we present deterministic parallel algorithms for the coarse-grained multicomputer (CGM) and bulk synchronous parallel (BSP) models for solving the following well-known graph problems: (1) list ranking, (2) Euler tour construction in a tree,
(3) computing the connected components and spanning forest, (4) lowest common ancestor preprocessing, (5) tree contraction
and expression tree evaluation, (6) computing an ear decomposition or open ear decomposition, and (7) 2-edge connectivity
and biconnectivity (testing and component computation). The algorithms require O(log p) communication rounds with linear sequential work per round (p = no. processors, N = total input size). Each processor creates, during the entire algorithm, messages of total size O(log (p) (N/p)) .
The algorithms assume that the local memory per processor (i.e., N/p ) is larger than p
ε
, for some fixed ε > 0 . Our results imply BSP algorithms with O(log p) supersteps, O(g log (p) (N/p)) communication time, and O(log (p) (N/p)) local computation time.
It is important to observe that the number of communication rounds/ supersteps obtained in this paper is independent of the problem size, and grows only logarithmically with respect to p . With growing problem size, only the sizes of the messages grow but the total number of messages remains unchanged. Due
to the considerable protocol overhead associated with each message transmission, this is an important property. The result
for Problem (1) is a considerable improvement over those previously reported. The algorithms for Problems (2)—(7) are the
first practically relevant parallel algorithms for these standard graph problems.
Received July 5, 2000; revised April 16, 2001. 相似文献
3.
On 31 July 1981, 550 KWe were delivered to the remote village of Tabernas, Almeria, Spain from the Distributed Collector Solar Thermal-Electric Plant designed and built by an International Consortium and sponsored by nine countries of the International Energy Agency (IEA). The project is now completed and in operation. The management and startup experience are summarized. 相似文献
4.
In this paper, we study the problem of implementing standard data structures on a hypercube multiprocessor. We present a technique for efficiently executing multiple independent search processes on a class of graphs called ordered h-level graphs. We show how this technique can be utilized to implement a segment tree on a hypercube, thereby obtaining O(long2n) time algorithms for solving the next element search problem, the trapezoidal composition problem, and the triangulation problem. 相似文献
5.
Regioselective radioiodination of N-trifluoroacetyl 3,4-dimethoxy-6-trifluoroacetoxymercurio-L-phenylalanine ethyl ester 1 under no-carrier-added condition gave 6-[125I]iodo protected L-DOPA with a labeling efficiency of more than 85%, and no-carrier-added 6-[125I]I-L-DOPA was obtained with a radio-chemical purity of over 95% after hydrolysis and chromatography. A nonradioactive standard of 6-iodo protected L-DOPA was synthesized by the iododemercuration of 6-mercuric trifluoroacetate protected L-DOPA 1 using I2 in chloroform. 6-[125I]I-L-DOPA showed high brain accumulation and rapid blood clearance in mice. The rat brain slice studies indicated high affinity of 6-[125I]I-L-DOPA for carrier-mediated and stereoselective active transport systems. The tissue homogenate analysis revealed that most of the accumulated radioactivity was intact 6-[125I]I-L-DOPA. Thus, 6-[123I]I-L-DOPA appears to be a suitable single photon emission computed tomography (SPECT) tracer for the selective measurement of cerebral L-amino acid transport, having no affinity for dopamine metabolism. 相似文献
6.
Esterification of Kraft lignin as a method to improve structural and mechanical properties of lignin‐polyethylene blends 下载免费PDF全文
Lignin is a promising candidate for blends with thermoplastic polymers. Still, this endeavour is a challenge due to poor compatibility between both components. In this article, the effect of lignin esterification on the improvement of the compatibility between hardwood Kraft lignin and high‐density polyethylene (PE‐HD) is investigated. For this purpose, lignin was esterified with acetic, propionic, and butyric anhydride; its amount in the blends varied from 10 to 40%. Light microscopic images of blends show a reduction in particle size and a more homogeneous distribution with increasing length of the ester carbon chains (C2 to C4). Modification of lignin enhances the moduli and strength characteristics of the blends. Butyrated lignin performs best, as tensile strength of blends can be retained near that of pure PE‐HD with up to 40% lignin content. An additional investigation of unmodified lignin with reduced particle size confirms that modification is the decisive factor to enhance blend properties; a sole reduction of particle size is insufficient. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44582. 相似文献
7.
T. Holzhauser L. I. Dehne A. Hoffmann D. Haustein S. Vieths 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1998,206(1):1-8
Peanuts are one of the most allergenic foods known. The presence of hidden allergens in processed food for reasons of mislabelling
or cross-contamination expose allergic individuals to unpredictable risks, especially since highly sensitized subjects may
experience severe anaphylactic reactions. The protection of consumers requires specific and sensitive methods for the detection
of trace amounts of potentially allergenic peanut components. A rocket immunoelectrophoresis (RIE) procedure was developed
allowing the detection of even spurious contaminations with peanut protein. For precipitation of peanut protein a commercially
available antiserum was used. By amplifying precipitates with a secondary immunodetection step, 20 ng/ml peanut protein in
chocolate extract, equivalent to 0.0002% peanut in chocolate, could still be detected. Model chocolate spiked with various
amounts of peanut was investigated down to 0.001% peanut (10 ppm), the limit of quantitative determination. The method was
optimized for detection of peanut in chocolate samples. Non-chocolate samples had to be standardized with a chocolate matrix
prior to analysis in order to obtain a uniform response. Cross-reactivities with other food proteins did not occur. The method
showed high recoveries of 85–101% for chocolate samples down to 10 ppm peanut and good reproducibility with coefficients of
variation of ≤ 5 % for samples of ≥ 15 ppm peanut protein. The applicability of this method in the detection of peanut protein
in various food commodities was demonstrated: two unlabelled products and two products which did not have peanut listed as
an ingredient were identified as containing peanut protein. In all cases where peanut was listed, peanut protein could be
determined. The results of RIE were always confirmed by those of a new cell-mediator-release assay that is based on a rat
basophil leukaemia (RBL) cell-line (RBL-2H3), cells that are a functional equivalent to mucosal mast cells. Measuring the
release of β-hexosaminidase resulting from cross-linking of basophil-bound peanut-specific immunoglobulin E, the assay mimics
a main event of the allergic type-I reaction. The cell assay was adapted for food matrices and peanut could be detected down
to 0.01% which additionally demonstrated in vitro that even trace amounts of peanut protein could elicit allergic reactions.
Received: 28 May 1997 / Revised version: 11 July 1997 相似文献
8.
W Schepp K Dehne T Riedel J Schmidtler K Schaffer M Classen 《Canadian Metallurgical Quarterly》1996,57(6):398-405
Six patients with hepatocellular carcinoma were subjected to percutaneous microwave coagulation therapy (PMCT) by ultrasonic guiding. The size of the main tumor in the present cases was limited to not more than 2 cm. From 18 to 48 days after PMCT, each patient was subjected to surgery and pathological examination. By macroscopic observation, the PMCT area including both non-tumor and tumor regions looked yellowish white, and the boundary was clearly recognized. In the histological examination, the coagulation area surrounded by fibrous capsule was found, and deletion of nuclei and changes in stainability were observed in the marginal region. These changes indicated obvious coagulation necrosis, but the changes became less intense toward the center in the area, and in some portions, the tissue was indistinguishable from viable cells by light microscopy. In 2 cases out of the 6, part of the tumor remained outside the coagulation area. Since only the area determined by the microwave electrode is coagulated to cause necrosis on PMCT, sufficient safety margin should be required. 相似文献
9.
A small-scale training programme for birth attendants in a remote area of Burkina Faso was evaluated two years after it had been started. The evaluation methods included interviews with trained birth attendants and the analysis of health service statistics and survey data. The findings showed that the programme had been moderately successful in imparting knowledge and overcoming cultural inhibitions about assisted deliveries. However, the effectiveness of the programme was severely curtailed by structural deficits in the health system, especially lack of skilled staff, supervision and transport. In deprived areas such as the Sahel, it is probably the health centre, the hospital and the referral system that should be the first priority for improvement, rather than grass-roots practices. 相似文献
10.
Peter Diermayr und Lutz Dehne 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1990,190(6):516-520
Zusammenfassung Es wird eine Methode zur kontrollierten enzymatischen Hydrolyse von Proteinen im pH-Bereich 1,5–3,5 beschrieben. Bei konstantem pH-Wert (pH-stat) kann die bei der Hydrolyse der Peptid-bindung verbrauchte Menge an Säure zur Berechnung des Hydrolysegrades eines vorgegebenen Proteinsubstrates verwendet werden. Die berechneten Hydrolysewerte stimmen gut mit den aus der Zahl der freigesetzten Aminogruppen bestimmten überein. Die Untersuchungen werden mit Rinderserumalbumin als Modellprotein durchgeführt.
Herrn Dr. Roland Vogel zum 65. Geburtstag gewidmet 相似文献
Controlled enzymatic hydrolysis of proteins at low pH values 1. Experiments with bovine serum albumin
Summary A method for the controlled enzymatic hydrolysis of proteins in the pH range 1.5–3.5 is described. The hydrolysis of the peptide bond at a constant pH value (pH-stat) can be followed by the consumption of acid. This value is used for calculating the degree of protein hydrolysis. The degree of hydrolysis is in good accordance with the number of amino groups liberated during the course of hydrolysis. These experiments are carried out using bovine serum albumin as the substrate.
Herrn Dr. Roland Vogel zum 65. Geburtstag gewidmet 相似文献