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  • 1
    ISSN: 0025-5874
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. We consider the Burgers equation with a periodic force $\frac{\partial}{\partial t}u+u\cdot\nabla u=\frac12\Delta u+\nabla V(x)$ which presents a simplified model for turbulence. We are interested in the asymptotic behaviour of solutions for $t\to\infty$ . This problem has been studied by Sinai who uses a probabilistic and very technical approach. Using methods from spectral theory we get similar results. This functional analytic approach gives an easier proof. For certain initial data (periodic or some random perturbations of those) we show time-convergence towards a deterministic periodic limit solution related to the ground state of a certain Schrödinger operator.
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  • 2
    ISSN: 1573-904X
    Keywords: near-IR spectroscopy ; film coating ; chemometrics ; pharmaceutical analysis ; process monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The purpose of this study was to investigate the potential of near-infrared (near-IR) spectroscopy for non-destructive at-line determination of the amount of polymer coat applied to tablet cores in a Wurster column. Methods. The effects of coating composition on the near-IR spectroscopic determination of ethylcellulose (Aquacoat ECD-30) or hydroxypropylmethylcellulose (HPMC)-based (Spectrablend) coating were evaluated, as were the performance of several chemometric techniques. Results. Tablets were coated with up to 30% ethylcellulose or 22% HPMC, and samples were pulled at regular intervals during each coating run. Near-IR reflectance spectra of the intact tablets were then collected. The spectra were preprocessed by multiplicative scatter correction (MSC) or second derivative (D2) calculations, and calibrations developed using either principal components (PCs) or multiple spectral wavelengths. The near-IR method provided predictions of film applied with standard errors of 1.07% w/w or less. Conclusions. Near-IR spectroscopy can be profitably employed in a rapid and non-destructive determination of the amount of polymer film applied to tablets, and offers a simple means to monitor the film coating process.
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  • 3
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In an attempt to determine whether the fluorescent in situ hybridization (FISH) can be used as a rapid approach for the identification of aneuploidy in premalignant cervical smears, a centromeric probe for chromosome 1 was used. The results from the FISH experiments were compared with measurements of the overall DNA content obtained by means of an image analysis system. With progression to neoplasia, a decrease of the frequency of cells with two spots was observed, due to an increasing polysomy of chromosome 1. As far as the DNA content was concerned, an increasing DNA index and 5C-exceeding ratio (fraction of cells with a DNA content higher than 5C) was observed. Classification of the FISH results by a linear discriminant analysis revealed that 67.6% of the cases were classified in agreement with the CIN classification. These data suggest that chromosome 1 may be considered as a marker chromosome for pre-malignant cervical lesions and that the DNA content measurements are complementary to the FISH results.
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  • 4
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary To obtain more information about the relationship between numerical aberrations of chromosome 1 and the overall DNA content of breast cancer cells, fluorescent in situ hybridization with a pericentromeric probe for this chromosome and image analysis based densitometry were carried out on imprints of benign (15 cases, mainly fibroadenomas) and malignant breast disease (31 invasive ductal carcinomas out of 45 cases). The most pronounced aneuploidy was observed in invasive ductal and lobular carcinoma cases both by in situ hybridization and DNA content (76.7 and 75.0% were aneuploid). The frequency of cells with two spots for chromosome 1 was 48.3 and 51.5%, respectively, as compared to 80.3% in control lymphocytes. There was a weak overall correlation (r2 = 0.83) between DNA content and copy number of chromosome 1 in the malignant samples, although some of the DNA diploid/near diploid carcinomas showed a marked aneusomy for this chromosome. Also, some aberrations were present in the benign breast disease samples. Classification of cases by a linear discriminant analysis was most accurate when both techniques were combined (77% of cases correctly classified, according to anatomo-pathological diagnosis). The variables which received the highest weight in the linear discriminant function are the percentage DNA-diploid cells and the fraction of cells with two spots for chromosome 1. The sensitivity and sources of error of both techniques is considered.
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  • 5
    ISSN: 1432-0878
    Keywords: Thyroid cartilage ; Immunohistochemistry ; Asbestoid fibers ; Amianthoid fibers ; Collagens ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The distribution of type I, II, IX, XI and X collagens in and close to areas of asbestoid (amianthoid) fibers in thyroid cartilages of various ages was investigated in this study. Asbestoid fibers were first detected in thyroid cartilage from a 3-year-old male child. Areas of asbestoid fibers functionally appear to serve as guide rails for vascularization of thyroid cartilage. Alcian blue staining in the presence of 0.3 M MgCl2 revealed a loss of glycosaminoglycans in areas of asbestoid fibers. In addition, the fibers reacted positively with antibodies against collagen types II, IX and XI, but showed no staining with antibodies to collagen types I and X. Territorial matrix of adjacent chondrocytes showed the same staining pattern. In addition to staining for type II, IX and XI collagens, asbestoid fibers showed strong immunostaining for type I collagen after puberty but not for type X collagen. However, groups of chondrocytes within areas of asbestoid fibers reacted strongly with antibodies to type X collagen, suggesting that this collagen plays an important role in matrix of highly differentiated chondrocytes. The finding that these type X collagen-positive chondrocytes also revealed immunostaining for type I collagen confirms previous studies showing that hypertrophic chondrocytes can further differentiate into cells that are characterized by the synthesis of type X and I collagens.
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  • 6
    ISSN: 1432-0878
    Keywords: Key words CNTF ; Photoreceptor ; Retina ; Development ; Differentiation ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The development of photoreceptors in the mammalian retina is thought to be controlled by extrinsic signals. We have shown previously that ciliary neurotrophic factor (CNTF) potently inhibits photoreceptor differentiation in cultures of rat retina. The present study analyzes which developmental processes are affected by CNTF. Rod differentiation as determined by opsin and recoverin immunocytochemistry was effectively blocked by CNTF and leukemia inhibitory factor, but not by other neurotrophic agents tested. CNTF did not influence proliferation, cell death, or survival, and had no effect on the downregulation of nestin immunoreactivity in progenitor cells. Opsin-positive rods could be reverted to an opsin-negative state initially, but became unresponsive to CNTF later. No compensatory increase in the number of other cell types was observed. Application of neutralizing antibodies against CNTF revealed that rod development was partially blocked by an endogenous CNTF-like molecule in control cultures. Our results suggest that CNTF can act as a specific negative regulator of rod differentiation. Its action on photoreceptor precursor cells could serve to synchronize the maturation of photoreceptors, which are born over an extended period of time. Together with other stimulatory signals, CNTF may thus control the temporally and numerically correct integration of photoreceptors into the retinal network.
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  • 7
    ISSN: 1619-7089
    Keywords: Key words: Recurrent glioma ; Grading ; Fluorine-18 fluorodeoxyglucose ; l-3-[123I]iodo-α-methyltyrosine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract . Based on the results of stereotactic biopsy, we evaluated in a prospective fashion the efficiency of l-3-[123I]iodo-α-methyltyrosine-single-photon emission tomography (SPET) and [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) in the detection and grading of recurrences in patients previously treated for gliomas. The patient population comprised 30 individuals, nine with astrocytomas of grade II, ten with astrocytomas of grade IV, three with oligoastrocytomas of grade II, six with oligodendrogliomas of grade II and two with anaplastic oligodendrogliomas of grade III) suspected of recurrence and scheduled for further treatment. IMT SPET data were acquired using either by dual-or a triple-headed SPET camera, Multispect 2/3. FDG uptake was measured with an ECAT ART PET camera. Two independent observers classified PET and SPET images as positive or negative for tumour tissue. Uptake of FDG and IMT was evaluated visually and, in the case of IMT, also quantitatively by calculating the ratios between tracer accumulation in the lesion and the unaffected contralateral regions of reference using the region of interest (ROI) technique. The PET and SPET results were compared with the histopathological findings obtained either by stereotactic biopsy or in one case by open surgery. Glucose metabolism and amino acid uptake of recurrences of brain tumours as assessed by FDG-PET and IMT-SPET correlated highly with the histopathological findings. Based on the histopathological data, FDG-PET and IMT-SPET findings confirmed recurrence in all cases of high-grade gliomas (IV). A difference could be demonstrated in low-grade (II–III) tumour recurrences. True-positive IMT-SPET results were found in 86% of grade III and 75% of grade II recurrences, whereas FDG-PET yielded a sensitivity of 71% in tumours of grade III and 50% in those of grade II. With respect to the grade of malignancy of brain tumours at recurrence, IMT-SPET, in contrast to FDG-PET, does not permit adequate in vivo grading of non-mixed brain tumours of astrocytic or oligodendroglial origin. However, in this study FDG-PET did not permit discrimination between upgrading of low-grade oligoastrocytomas (II) into anaplastic oligodendrogliomas (III) and upgrading into glioblastomas (IV) The results of this study indicate that FDG-PET and IMT-SPET are equivalent to stereotactic biopsy in their ability to identify high-grade tumours at recurrence. IMT-SPET proved to be superior to FDG-PET in confirming low-grade recurrences. In the case of suspected progression of the grade of malignancy in ordinary gliomas, FDG-PET correlated significantly with the histopathological grading, whereas IMT-SPET did not. However, tumour grading by FDG-PET has a limitation in mixed brain tumours in that it is not possible to discriminate between progression of the oligo- versus the astrocytic tumour entity. In this case histopathological evaluation of the tumour grade remains necessary.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Mathematische Zeitschrift 221 (1996), S. 507-512 
    ISSN: 0025-5874
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
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  • 9
    ISSN: 0942-0940
    Keywords: Epidermoid cyst ; diploic cyst ; tension pneumocephalus ; computerized tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 10
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Research was carried out on the use of ceramics as supports to host mammalian cells. The research was part of a programme whose priority was to study the possibility of using ceramics in the non-traditional sector of the biomedical field. The aim of the study was also to verify the suitability of particular types of ceramics dealt with in the literature for these applications. Among the different samples tested the cordieritic one proved to be very interesting, at least in relation to the cellular cultures considered. The chemical composition of the material is not, however, the only important aspect, since other parameters concur to make the hosting of cells highly acceptable. Of particular importance is the rugosity and porosity of the surface and its flaking, not only externally, but also in the pores.
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