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  • 1
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract For strongly nonorthogonal grids, the convergence difficulty is often encountered in the SIMPLE method unless very low relaxation factors are adopted. This is because that the cross derivatives of pressure corrections are usually neglected in deriving the pressure-correction equation. In this study, an approximate treatment is proposed to deal with the cross derivatives in the pressure-correction equation. Computations are performed for various laminar flows in a nonorthogonal cavity and the turbulent flows through the compressor cascades. It is found that the convergence difficulty encountered in the SIMPLE method for strongly nonorthogonal grids can be overcome when the SIMPLEC method is employed. In addition, when the present approximate treatment for the cross derivatives is adopted in the SIMPLEC method, the convergence rate can be speeded up in comparison with the original SIMPLEC method. In some cases, the CPU time can be decreased by more than 60%. The computational results are also compared with the numerical results of others and the available experimental data.
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  • 2
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary.  An alpha-herpesvirus has been associated recently with green turtle fibropapilloma (FP). To further clarify the role of this newfound green turtle herpesvirus (GTHV) in the pathogenesis of FP, various normal-appearing tissues and organs (including skin, eye, brain, heart, liver, spleen, intestine, lung, kidney, nerve, gonad, tongue, gall bladder, urinary bladder, thyroid and peripheral blood mononuclear cells (PBMC) from blood) and tumor tissues from 19 green turtles (Chelonia mydas) with FP, and tissues from three green turtles without FP, collected during 1997 to 1999 in the Hawaiian Islands, were tested for GTHV sequences by nested polymerase chain reaction (PCR), using GTHV-specific oligonuclotide primers. GTHV sequences were detected in all tumors (51/51) and most tissues (133/167) of tumored turtles. By contrast, such sequences were undetectable in tissues (0/28) of three non-tumored turtles. Analysis of GTHV sequences detected in different tissues and tumors revealed a low degree of genetic diversity (〈1%). The wide distribution of this newfound herpesvirus in tumors and tissues of tumored green turtles and its absence in tissues of non-tumored turtles, argues for an etiologic role in FP.
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  • 3
    ISSN: 1433-0490
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract. According to Cayley's tree formula, there are n n-2 labelled trees on n vertices. Prüfer gave a bijection between the set of labelled trees on n vertices and sequences of n-2 numbers, each in the range 1, 2, ..., n . Such a number sequence is called a Prüfer code. The straightforward implementation of his bijection takes O(n log n ) time. In this paper we propose an O(n) time algorithm for the same problem. Our algorithm can be easily parallelized so that a Prüfer code can be generated in O (log n ) time using O(n) processors on the EREW PRAM computational model.
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  • 4
    ISSN: 1432-0533
    Keywords: Key words SCA6 ; Purkinje cell ; Immunohistochemisry ; Calbindin-D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Spinocerebellar ataxia type 6 (SCA6) was recently identified as a form of autosomal dominant spinocerebellar ataxia associated with a small CAG repeat expansion of the gene encoding an α 1 A-voltage-dependent calcium channel gene subunit on chromosome 19p13. In this study 50-μm-thick sections of cerebellar tissue from one patient with SCA6 were subjected to free-floating immunohistochemical staining with calbindin-D and parvalbumin antibodies. Severe loss of Purkinje cells was found, particularly in the vermis, and various morphological changes in Purkinje cells and their dendritic arborizations were demonstrated. Many of the remaining Purkinje cells were found to have heterotopic, irregularly shaped nuclei, an unclear cytoplasmic membrane outline, and somatic sprouts. Increased numbers of spine-like protrusions from swelling dendritic arborizations were found in the molecular layer. The axonal arrangement was disordered, and many torpedos were found in the granular layer and white matters. These morphological changes are completely different from those observed in paraneoplastic cerebellar degeneration (PCD) and multiple system atrophy (MSA) and are considered to be related to the genetic abnormality that causes abnormal development of Purkinje cells.
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  • 5
    ISSN: 0992-7689
    Keywords: Oceanography: general (limnology; numerical modeling) ; Oceanography: physical (currents)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We study how a coastal obstruction (peninsula or coastal island) affects the three-dimensional barotropic currents in an oblong rectangular basin with variable bathymetry across the basin width. The transverse depth profile is asymmetric and the peninsula or island lies in the middle of the long side of the rectangle. A semi-spectral model for the Boussinesq-approximated shallow water equations, developed in Haidvogel et al. and altered for semi-implicit numerical integration in time in Wang and Hutter, is used to find the steady barotropic state circulation pattern to external winds. The structural (qualitative) rearrangements and quanti2tative features of the current pattern are studied under four principal wind directions and different lengths of the peninsula and its inclination relative to the shore. The essentially non-linear relationships of the water flux between the two sub-basins (formed by the obstructing peninsula) and the corresponding cross-sectional area left open are found and analysed. It is further analysed whether the depth-integrated model, usually adopted by others, is meaningful when applied to the water exchange problems. The flow through the channel narrowing is quantitatively estimated and compared with the three-dimensional results. The dynamics of the vortex structure and the identification of the up-welling/down-welling zones around the obstruction are discussed in detail. The influence of the transformation of the peninsula into a coastal island on the global basin circulation is considered as are the currents in the channel. The geometric and physical reasons for the anisotropy of the current structure which prevail through all obtained solutions are also discussed.
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  • 6
    ISSN: 1432-0584
    Keywords: Key words Acute myeloid leukemia ; Erythrophagocytosis ; Tetraploidy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Numerical change of chromosomes is common in acute myeloid leukemia (AML). However, a chromosome number as high as near-tetraploidy is very rare, especially in minimally differentiated AML (AML-M0). Erythrophagocytosis by reactive or malignant histiocytes is common in malignant hematological diseases; however, erythrophagocytosis by leukemic blasts is also very rare, especially in AML-M0. We report here the first case of AML-M0 with both of these unique characteristics: a near-tetraploid karyotype and erythrophagocytosis by leukemic blasts.
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  • 7
    ISSN: 1432-0630
    Keywords: PACS: 81.15.Fg; 61.46.+w; 42.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. The processes leading to the formation of Cu:Al2O3 composite films on Si (001) with a well defined nanostructure by alternate pulsed laser deposition (a-PLD) in vacuum are investigated. Alternately amorphous Al2O3 layers and Cu nanocrystals nucleated on the Al2O3 surface are formed, according to the PLD sequence. The Al2O3 deposited on the Cu nanocrystals fills in the space between them until they are completely buried, and subsequently, a continuous dense layer with a very flat surface (within 1 nm) is developed. The nucleation process of the nanocrystals and their resulting oblate ellipsoidal shape are discussed in terms of the role of the energetic species involved in the PLD process and the metal–oxide interface energy.
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  • 8
    ISSN: 1432-0630
    Keywords: PACS: 61.10.Nz; 68.65; 71.20.T; 81.05.Tp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. We have synthesized the ytterbium fulleride compounds YbxC60 (x=1–6) at a range of lower temperature (530 °C–570 °C). Except for the nominal composition Yb3C60 compound, which has been reported in the references, we also obtained a new phase Yb6C60, whose structure is orthorhombic with space group P21212 and unit cell parameters a=21.28 Å, b=20.13 Å and c=15.89 Å. The YbxC60 compounds are sensitive to oxygen, the samples exposed in air convert to an amorphous phase and Yb2O3 compound.
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  • 9
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The factors responsible for ALS-parkinsonism dementia complex (ALS-PDC), the unique neurological disorder of Guam, remain unresolved, but identification of causal factors could lead to clues for related neurodegenerative disorders elsewhere. Earlier studies focused on the consumption and toxicity of the seed of Cycas circinalis, a traditional staple of the indigenous diet, but found no convincing evidence for toxin-linked neurodegeneration. We have reassessed the issue in a series of in vitro bioassays designed to isolate non-water soluble compounds from washed cycad flour and have identified three sterol β-d-glucosides as potential neurotoxins. These compounds give depolarizing field potentials in cortical slices, induce alterations in the activity of specific protein kinases, and cause release of glutamate. They are also highly toxic, leading to release of lactate dehydrogenase (LDH). Theaglycone form, however, is non-toxic. NMDA receptor antagonists block the actions of the sterol glucosides, but do not compete for binding to the NMDA receptor. The most probable mechanism leading to cell death may involve glutamate neuro/excitotoxicity. Mice fed cycad seed flour containing the isolated sterol glucosides show behavioral and neuropathological outcomes, including increased TdT-mediated biotin–dUTP nick-end labelling (TUNEL) positivity in various CNS regions. Astrocytes in culture showed increased caspase-3 labeling after exposure to sterol glucosides. The present results support the hypothesis that cycad consumption may be an important factor in the etiology of ALS-PDC and further suggest that some sterol glucosides may be involved in other neurodegenerative disorders.
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  • 10
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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