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  • 1
    ISSN: 1436-4646
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In the feasible region of a linear programming problem, a number of “desirably good” directions have been defined in connexion with various interior point methods. Each of them determines a contravariant vector field in the region whose only stable critical point is the optimum point. Some interior point methods incorporate a two- or higher-dimensional search, which naturally leads us to the introduction of the corresponding contravariant multivector field. We investigate the integrability of those multivector fields, i.e., whether a contravariantp-vector field isX p -forming, is enveloped by a family ofX q 's (q 〉 p) or envelops a family ofX q 's (q 〈 p) (in J.A. Schouten's terminology), whereX q is aq-dimensional manifold. Immediate consequences of known facts are: (1) The directions hitherto proposed areX 1-forming with the optimum point of the linear programming problem as the stable accumulation point, and (2) there is anX 2-forming contravariant bivector field for which the center path is the critical submanifold. Most of the meaningfulp-vector fields withp ⩾ 3 are notX p -forming in general, though they envelop that bivector field. This observation will add another circumstantial evidence that the bivector field has a kind of invariant significance in the geometry of interior point methods for linear programming. For a kind of appendix, it is noted that, if we have several objectives, i.e., in the case of multiobjective linear programs, extension to higher dimensions is easily obtained.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1436-0691
    Keywords: metastatic liver cancer ; cancer of the papilla of the duodenum ; metastatic tumor at the common bile duct ; Wilms' tumor (adult type)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The major issue in treating metastatic liver cancer is: how far should we perform resection? We believe that only reports of long-term survival afford an answer to this problem. We report three such patients. The first patient underwent pancreatoduodenectomy for cancer of the papilla of the duodenum and resection of metastatic liver cancer. She is alive without recurrence 15 years and 1 month after the initial surgery. The second patient received low anterior resection for rectal cancer, extended right lobectomy for liver metastasis, and pancreatoduodenectomy for metastasis at the common bile duct. She survived 6 years and 9 months after the initial surgery. The third patient underwent right nephrectomy for Wilms' tumor (adult type), extended right lobectomy for liver metastasis, and repeat resection of recurrences at the mediastinum and in the thoracic and abdominal walls. She is alive 21 years and 2 months after the initial surgery. These experiences have prompted us to carry out resection when surgery is deemed feasible.
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  • 3
    ISSN: 1573-1111
    Keywords: Crown ether ; alkylphosphoric acid ; lithium transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Mixed carrier systems composed of crown ethers and alkylphosphoric acids have been studied as lithium ionophores using a solvent extraction technique and in transport across liquid membranes. The combination of dibenzo-14-crown-4 and bis(2-ethylhexyl) phosphoric acid showed a synergistic enhancement on both lithium ion selectivity and transport rate. The synergistic effects depended strongly upon crown ether structure and the enhancement was observed only when the metal cation corresponded to the crown ether's cavity diameter. Complex formation in the organic phase was assessed by use of FAB-mass spectrometry.
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  • 4
    ISSN: 1573-0743
    Keywords: three-dimensional reconstruction ; transesophageal echocardiography ; mitral valve stenosis ; Doppler-echocardiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was the evaluation of the diagnostic potentials of transesophageal 3D-echocardiography in the determination of mitral valve stenosis. 54 patients were investigated by transthoracic and multiplane transesophageal echocardiography. In 41 patients cardiac catheterization was performed. 3D-echocardiographic data acquisition was performed by automatic transducer rotation at 2° increments over a span of 180°. The transesophageal probe was linked to an ultrasound unit and to a 3D-workstation capable of ECG- and respiration gated data acquisition, postprocessing and 2D/ 3D image reconstruction. The mitral valve was visualized in sequential cross-sectional planes out of the 3D data set. The spatial position of the planes was indicated in a reference image. In the cross-sectional plane with the narrowest part of the leaflets the orifice area was measured by planimetry. For topographic information a 3D view down from the top of the left atrium was reconstructed. Measurements were compared to conventional transthoracic planimetry, to Doppler-echocardiographic pressure half time and to invasive data. The mean difference to transthoracic planimetry, pressure half time and to invasive measurements were 0.3 ± 0.1 cm2, 0.2 ± 0.1 cm2 and 0.1 ± 0.1 cm2, respectively. Remarkable differences between the 3D- echocardiographic and the 2D- or Doppler- echocardiographic methods were observed in patients with severe calcification or aortic regurgitation. In 22% of the patients the 3D data set was not of diagnostic quality. New diagnostic information from a 3D view of the mitral valve could be obtained in 69% of the patients. Thus, although image quality is limited, 3D- echocardiography provides new topographic information in mitral valve stenosis. It allows the use of a new quantitative method, by which image plane positioning errors and flow-dependent calculation is avoided.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6562-6564 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electronic states of a range of Fe-Si alloys were investigated by x-ray and ultraviolet photoelectron spectroscopy. Previous work has shown that in Fe-Si alloys, the 6.5-wt % Si-Fe alloy has the optimum soft magnetic properties because of its zero magnetostriction. The binding energy (BE) of the Fe 2p, Fe 3s, Fe 3p, and Si 2p levels and the Fe 3d valence-band structures of Fe-Si alloys were measured over the range from 0 to 7 wt % Si. The BE of the Fe 3s and Fe 3p levels and the Fe 3d valence band of Fe-Si alloys showed small shifts of the peaks toward higher BEs than pure Fe. These peak shifts are related to the change in density of Fe 3d states with the addition of Si: the decrease in the density of states near the Fermi energy, the decrease in the energy difference between the majority and minority spin bands, and the increase in the number of electrons with minority spin. The results of the photoelectron spectroscopic analyses agree with the observed decrease in saturation magnetization from 2.15 T for pure Fe to 1.80 T for 6.5-wt % Si-Fe.
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  • 6
    ISSN: 0945-3245
    Keywords: AMS(MOS): 65D30 ; CR: 5.16
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary The IMT rule, which is especially suited for the integration of functions with end-point singularities, is generalized by introducing parameters and also by repeatedly applying the parametrized IMT transformation. The quadrature formulas thus obtained are improved considerably both in efficiency and in robustness against end-point singularities. Asymptotic error estimates and numerical results are also given.
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  • 7
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract HLA-C loci frequently have an unclassifiable “blank (CwBL)” specificity. It is unclear whether HLA-C specificities associated with the haplotypes of A24 Bw52 CwBL DR2 DQw1 and Aw33 B44 CwBL DRw13 DQw1 in Japanese (tentatively named Cx52 and Cx44, respectively) really exist. Southern hybridization experiments revealed that restriction enzyme-cleaved genomic DNA from AKIBA, consanguineous HLA homozygote, two other homozygotes with the former haplotype, and three homozygous cells with the latter haplotype hybridized strongly with an HLA-C-specific probe. We have screened the cDNA library constructed from AKIBA to isolate cDNA clones encoding the putative Cx52 antigen, and picked up 103 cDNA clones with HLA-class I DNA probes as possible candidates. By restriction enzyme mapping and Southern hybridization of selected clones, we identified three isotypes of cDNA clones, pA01, pB55, and pC68, which appeared to encode A24, Bw52, and Cx52, respectively. The nucleotide sequence of pC68 showed higher homology with exons of the HLA-C gene than with those of the HLA-A and HLA-B genes, especially in exons 6–8 which include the HLA-C-specific region. Comparison of amino acid sequences showed more than 86% homology among Cw1, Cw2, Cw3, and new pC68-encoded Cx52 proteins. These results support the notion that the inability to define C antigens serologically in this Cx52 haplotype is not due to a HLA-C gene deletion or mutation, but to the absence of typing sera.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 414 (1989), S. 503-509 
    ISSN: 1432-2307
    Keywords: Alveolar soft part sarcoma ; Desmin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The many different theories on the histogenesis of alveolar soft part sarcoma (ASPS) have caused great confusion. Owing to the recent rapid advance in immunohistochemical studies, two major hypotheses have been proposed. One group of researchers supports the idea that ASPS shows myogenic differentiation, while the other group opposes the idea. This confrontation is essentially one between a group that believes in the immunohistochemically demonstrated presence of desmin in ASPS and a group that denies it. In the present study we detected desmin in 6 of 10 formalin-fixed paraffin sections (although there were differences due to the use of five commercially available types of anti-desmin antibodies). When acetone-fixed paraffin sections and periodate-lysin-paraformaldehyde (PLP)-fixed frozen sections were used in one and three cases, respectively, they were found to be desmin positive, regardless of the type of antibody. The consistent positivity for all anti-desmin antibodies in the cases treated with acetone or PLP is very suggestive of a myogenous origin of ASPS. It is important to take into consideration the fact that formalin-fixed paraffin sections are not very suitable for immunohistochemical study of desmin.
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  • 9
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0039-6028
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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