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61.
We show three linear-time algorithms for constructing planar straight-line grid drawings of outerplanar graphs. The first
and the second algorithm are for balanced outerplanar graphs. Both require linear area. The drawings produced by the first
algorithm are not outerplanar while those produced by the second algorithm are. On the other hand, the first algorithm constructs
drawings with better angular resolution. The third algorithm constructs outerplanar drawings of general outerplanar graphs
with O(n
1.48) area. Further, we study the interplay between the area requirements of the drawings of an outerplanar graph and the area
requirements of a special class of drawings of its dual tree.
Work partially supported by MUR under Project MAINSTREAM Algorithms for Massive Information Structures and Data Streams. 相似文献
62.
63.
Stefano Mercati Massimo MilaniLuca Montorsi Fabrizio Paltrinieri 《International Journal of Hydrogen Energy》2013
The working cycle of a novel hydrogen and power generation system based on aluminum combustion with water is analyzed in order to evaluate the best performance in terms of energy conversion efficiency. The system exploits the exothermic reaction between aluminum and steam and produces thermal power for a super-heated steam cycle and hydrogen as a by-product of the reaction. 相似文献
64.
Strains of Clostridium butyricum that produce botulinal toxin type E have been implicated in outbreaks of foodborne botulism in China, India, and Italy, yet the conditions that are favorable for the growth and toxinogenesis of these strains remain to be established. We attempted to determine the temperatures and pH levels that are most conducive to the growth of and toxin production by the six strains of neurotoxigenic C. butyricum that have been implicated in outbreaks of infective and foodborne botulism in Italy. The strains were cultured for 180 days on Trypticase-peptone-glucose-yeast extract broth at various pHs (4.6, 4.8, 5.0, 5.2, 5.4, 5.6, and 5.8) at 30 degrees C and at various temperatures (10, 12, and 15 degrees C) at pH 7.0. Growth was determined by checking for turbidity; toxin production was determined by the mouse bioassay. We also inoculated two foods: mascarpone cheese incubated at 25 and 15 degrees C and pesto sauce incubated at 25 degrees C. The lowest pH at which growth and toxin production occurred was 4.8 at 43 and 44 days of incubation, respectively. The lowest temperature at which growth and toxin production occurred was 12 degrees C, with growth and toxin production first being observed after 15 days. For both foods, toxin production was observed after 5 days at 25 degrees C. Since the strains did not show particularly psychrotrophic behavior, 4 degrees C can be considered a sufficiently low temperature for the inhibition of growth. However, the observation of toxin production in foods at room temperature and at abused refrigeration temperatures demands that these strains be considered a new risk for the food industry. 相似文献
65.
Kaulich B Wilhein T Di FE Romanato F Altissimo M Cabrini S Fayard B Susini J 《Journal of the Optical Society of America. A, Optics, image science, and vision》2002,19(4):797-806
X-ray imaging in differential interference contrast (DIC) with submicrometer optical resolution was performed by using a twin zone plate (TZP) setup generating focal spots closely spaced within the TZP spatial resolution of 160 nm. Optical path differences introduced by the sample are recorded by a CCD camera in a standard full-field imaging and by an aperture photodiode in a standard scanning transmission x-ray microscope. Applying this x-ray DIC technique, we demonstrate for both the full-field imaging and scanning x-ray microscope methods a drastic increase in image contrast (approximately 20x) for a low-absorbing specimen, similar to the Nomarski DIC method for visible-light microscopy. 相似文献
66.
Petritoli A Ravegnani F Giovanelli G Bortoli D Bonafè U Kostadinov I Oulanovsky A 《Applied optics》2002,41(27):5593-5599
An airborne UV-visible spectrometer, the Gas Analyzer Spectrometer Correlating Optical Differences, airborne version (GASCOD/A4pi) was successfully operated during the Airborne Polar Experiment, Geophysica Aircraft in Antarctica airborne campaign from Ushuaia (54 degrees 49' S, 68 degrees 18' W), Argentina in southern spring 1999. The instrument measured scattered solar radiation through three optical windows with a narrow field of view (FOV), one from the zenith, two from the horizontal, as well as actinic fluxes through 2pi FOV radiometric heads. Only a few airborne measurements of scattered solar radiation at different angles from the zenith are available in the literature. With our configuration we attempted to obtain the average line-of-sight concentrations of detectable trace gases. The retrieval method, based on differential optical absorption spectroscopy, is described and results for ozone are shown and compared with measurements from an in situ instrument as the first method of validation. 相似文献
67.
68.
Studies in our laboratory have shown that as early as day 8.5 of development, mouse yolk sac cells can generate T cells when placed in a thymic microenvironment. At this stage, yolk sac cells can also differentiate into myeloid cells in vitro. B cell differentiation in vitro was achieved with day 9 yolk sac by providing a bone marrow stromal feeder layer. We have now established endothelial cell lines and clones from yolk sacs of day 8-12 mouse embryos. These vary in their ability to support stem cell maintenance and differentiation. Our principal work has been carried out with day 12 cloned endothelial cell lines. One clone supported the > 100 fold expansion of yolk sac hematopoietic stem cells that subsequently could generate B cells, T cells and myeloid cells both in vitro and in vivo. Preliminary experiments with endothelial cells from younger embryos are also described. 相似文献
69.
Fabrizio Lombardi 《Microelectronics Reliability》1982,22(4):887-894
Parallel systems with processing distributed in the various modules are very interesting examples of hardware/software tradeoffs within a complex structure. An example of such a system mode of N modules, has been considered. The implications of a common memory and a central controller are analysed and an availability model is derived.The division of the software task into subtasks is viewed as a source of possible deadlock of the structure. Series catastrophic states due to hard core units and software coupling are included in the availability analysis. 相似文献
70.