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  • 11
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Mantle peridotites of the Internal Liguride (IL) units (Northern Apennines) constitute a rare example of the depleted lithosphere of the Jurassic Ligurian Tethys. Detailed chemical (ICP-MS and SIMS techniques) and isotopic investigations on very fresh samples have been performed with the major aim to constrain the timing and mechanism of their evolution and to furnish new data for the geodynamic interpretation. The data are also useful to discuss some general geochemical aspects of oceanic-type mantle. The studied samples consist of clinopyroxene-poor spinel lherzolites, showing incipient re-equilibration in the plagioclase-facies stability field. The spinel-facies assemblage records high (asthenospheric) equilibration temperatures (1150–1250° C). Whole rocks, and constituent clinopyroxenes, show a decoupling between severe depletion in highly incompatible elements [light rare earth elements (LREE), Sr, Zr, Na, Ti] and less pronounced depletion in moderate incompatible elements (Ca, Al, Sc, V). Bulk rocks also display a relatively strong M(middle)REE/H(heavy)REE fractionation. These compositional features indicate low-degree (〈10%) fractional melting, which presumably started in the garnet stability field, as the most suitable depletion mechanism. In this respect, the IL ultramafics show strong similarity to abyssal peridotites. The Sr and Nd isotopic compositions, determined on carefully handpicked clinopyroxene separates, indicate an extremely depleted signature (87Sr/86Sr=0.702203–0.702285; 143Nd/144Nd=0.513619–0.513775). The Sm/Nd model ages suggest that the IL peridotites melted most likely during Permian times. They could record, therefore, the early upwelling and melting of mid ocean ridge basalt (MORB) type asthenosphere, in response to the onset of extensional mechanisms which led to the opening of the Western Tethys. They subsequently cooled and experienced a composite subsolidus evolution testified by multiple episodes of gabbroic intrusions and HT-LP retrograde metamorphic re-equilibration, prior to their emplacement on the sea floor. The trace element chemistry of IL peridotites also provides useful information about the composition of oceanic-type mantle. The most important feature concerns the occurrence of Sr and Zr negative anomalies (relative to “adjacent” REE) in both clinopyroxenes and bulk rocks. We suggest that such anomalies reflect changes in the relative magnitude of Sr, Zr and REE partition coefficients, depending on the specific melting conditions.
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The photoplate detection system of a spark source mass spectrometer has been recently replaced by a detector array consisting of 20 separate small channeltrons for simultaneous ion counting of up to 20 trace elements. The new multi-ion counting – spark source mass spectrometry (MIC-SSMS) technique combines the advantages of conventional SSMS with modern on-line detection of elements. It has important analytical features, such as simple and fast solid-state sample preparation, high precision (about 1–2%) and accuracy (4%) using multielement isotope dilution, high sensitivity which leads to short measuring times (10–50 min) and low detection limits (about 0.001–0.01 μg/g).
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 67 (1995), S. 139-145 
    ISSN: 1432-1246
    Keywords: Developmental toxicants ; Classification scheme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It is now widely accepted that describing and labeling of chemicals as developmental toxicants on a purely qualitative basis does not make sense. Agents possessing the potential to induce reproductive or developmental toxicity present a risk of human harm only under certain conditions. This critical fact cannot be properly communicated with a simple designation as “positive” or “negative”. Rather, a number of parameters that deal with dose or concentration, frequency, duration and route of exposure must also be conveyed. Unsubstantiated blacklisting is equally counterproductive for preventive medicine as downplaying of the toxicity of chemicals. Gender-based restrictions on exposure at workplaces of women of child-bearing age are neither socially acceptable nor scientifically justifiable. Therefore, the German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area published in 1983 a quantitatively based classification concept, which became effective in 1985 and was modified in the following years. The present contribution summarizes what is required for an integrated judgment on the relevance of laboratory and epidemiological data for predicting the potential risk associated with exposure at workplaces to occupational chemicals. Methyl mercury, carbon disulfide, dimethylformamide, ethanol, toluene,N,N-dimethyl acetamide, nitrous oxide, methanol, ethyl benzene, and phosphorus pentoxide will be described as examples of classified substances.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 361 (1998), S. 645-646 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A cold working steel was coated both with high temperature CVD (TiN) and moderate temperature CVD (Ti[C,N]). AES depth profiles show a significant difference at the interface, where a thin oxide layer remains detectable at deposition temperatures of 750 °C. It could be shown that an impedance signal at a frequency of 13 MHz is well suited to detect the early stages of the growth of a CVD coating.
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 1432-0630
    Keywords: PACS: 68.55.-a
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. A new development of the pulsed laser ablation (PLA) technique based on variable azimuth ablation (VAA) is reported. The VAA itself is based on periodic variations of the azimuth of the laser beam relative to the target at a constant angle of beam incidence. Such variations result in a suppression of cone–valley surface structures which tend to develop in the case of a fixed azimuth. VAA leads to high-level stabilization of the laser plume during a long-term deposition process. As a result, the VAA method stabilizes the deposition rate with a tolerance of only 3–6% instead of a 90% decrease in the rate as in conventional PLA. Different possibilities for the realization of the VAA technique based on 2- and 3-way target scans are discussed. In the case of large areas, VAA technique with a meander beam target scan is capable of the deposition of high-quality multicompositional superconducting films on tubes and tapes more than 1 m in length.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Aquatic sciences 57 (1995), S. 54-69 
    ISSN: 1420-9055
    Keywords: Nephelometry ; suspended particles ; mass-calibration ; Lake Lugano (Lago di Lugano)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Turbidity measurements by foreward scattering nephelometer have been regularly conducted on the north basin of Lake Lugano (Switzerland/Italy) since September 1992. In order to determine mass concentrations from these data, both, in-situ and laboratory calibration experiments have been performed in November and December 1992 on suspended matter of the hypolimnion. Results show: 1. Mass concentration/turbidity ratios are different in the two turbidity zones examined due to variation in the optical signature of the suspended matter. 2. Laboratory calibrations using suspended matter originating from the water depths of interest give representative results provided that physical and chemical alterations occuring during the particle transfer process remain negligible.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Der Chirurg 67 (1996), S. 779-787 
    ISSN: 1433-0385
    Keywords: Key words: Malignant melanoma ; Lymph node metastases ; Lymph node dissection ; Prognosis. ; Schlüsselwörter: Malignes Melanom ; Lymphknotenmetastasierung ; Lymphknotendissektion ; Prognose.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Die Indikation zur elektiven Lymphknotendissektion, ihre evtl. zukünftige Bedeutung als Stagingmaßnahme vor adjuvanten Therapieverfahren, die Prognose der therapeutischen Dissektion sowie die Identifizierung des Pförtner-Lymphknotens und die daraus sich ergebenden therapeutischen Konsequenzen sind die wichtigsten Aspekte der Lymphknotendissektion beim malignen Melanom. Die Indikation zur elektiven Dissektion orientiert sich nicht nur an der pT-Kategorie, sondern auch an der Tumorlokalisation, dem Tumortyp und dem Geschlecht des Patienten. Ein allgemein akzeptierter Konsens zur Auswahl der in Frage kommenden Patienten besteht noch nicht. Da die ersten Studien mit Chemo-/Immuntherapie bei nodal positiven Patienten eine Prognoseverbesserung zeigen, muß zukünftig auch die Lymphknotendissektion als Stagingmaßnahme diskutiert werden. Neue Anregungen wurden in den letzten Jahren durch die Identifikation des Pförtner(„sentinel“)-Lymphknotens eingebracht. Diese Methodik bedarf noch der weiteren Evaluierung, dürfte aber zukünftig einen wesentlichen Einfluß auf die Indikation zur elektiven Lymphknotendissektion nehmen. Mit eingetretener Lymphknotenmetastasierung verschlechtert sich die Prognose des malignen Melanoms global um 20–50 %, abhängig vom Ausmaß der Metastasierung. Die Thematik wird anhand der eigenen Ergebnisse diskutiert.
    Notes: Summary. Elective lymph node dissection and its potential as a staging procedure, the prognosis of established lymph node metastases and the sentinel lymph node identification procedure are the most important aspects of lymph node dissection in malignant melanoma. It is widely accepted that subgroups of patients benefit from elective lymph node dissection. The question of which parameters identify the relevant patients properly is still under discussion. pT-categories are the most important prognostic factor; however, localisation and type of tumour and the sex of the patients are additional parameters influencing patient selection. Recently, the first studies have identified subgroups of nodal positive patients who would profit from adjuvant chemo-/immunotherapy. Therefore, lymph node dissection as a staging procedure has to be discussed in the future. Identification of the sentinel lymph node is receiving increasing attention because of its potential influence on the reassessment of elective lymph node dissection. However, this method needs further evaluation. If lymph node metastases have occurred, the prognosis of malignant melanoma decreases by 20 %–50 %, depending on the extent of metastasis in the individual case. The relevant topics and results are discussed on the basis of data of the Surgical Department of the University Hospital of Erlangen-Nuremberg.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 14 (1995), S. 1344-1345 
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 19
    ISSN: 1617-4623
    Keywords: Key words Gene disruption ; Gene targeting ; Homologous recombination ; Plant transformation ; Physcomitrella patens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The analysis of phenotypic change resulting from gene disruption following homologous recombination provides a powerful technique for the study of gene function. This technique has so far been difficult to apply to plants because the frequency of gene disruption following transformation with constructs containing DNA homologous to genomic sequences is low (0.01 to 0.1%). It has recently been shown that high rates of gene disruption (up to 90%) can be achieved in the moss Physcomitrella patens using genomic sequences of unknown function. We have used this system to examine the specificity of gene disruption in Physcomitrella using a member of the Cab multigene family. We have employed the previously characterised Cab gene ZLAB1 and have isolated segments of 13 other closely related members of the Cab gene family. In the 199-bp stretch sequenced, the 13 new members of the Cab family show an average of 8.5% divergence from the DNA sequence of ZLAB1. We observed 304 silent substitutions and 16 substitutions that lead to a change in the amino acid sequence of the protein. We cloned 1029 bp of the coding region of ZLAB1 (including 177 of the 199 bp with high homology to the 13 new Cab genes) into a vector containing a selectable hygromycin resistance marker, and used this construct to transform P. patens. In three of nine stable transformants tested, the construct had inserted in, and disrupted, the ZLAB1 gene. There was no discernible phenotype associated with the disruption. We have therefore shown that gene disruption is reproducible in P. patens and that the requirement for sequence homology appears to be stringent, therefore allowing the role of individual members of a gene family to be analysed in land plants for the first time.
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 259 (1998), S. 656-663 
    ISSN: 1617-4623
    Keywords: Key wordsDrosophila ; Enhancer-promoter interactions ; Pig-1 ; SEBP1 ; Sgs-4
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Drosophila genes Pig-1 and Sgs-4 are adjacent and oppositely transcribed genes which share a common enhancer region located in the intergenic region between the two transcription start sites. Both genes are transcribed in the same tissue, the larval salivary gland, but they are expressed at different times, the expression switching from Pig-1 to Sgs-4 expression during development of the third-instar larva. Here we describe partial purification and functional analysis of a DNA-binding protein, secretion enhancer binding protein 1 (SEBP1), from nuclear extracts of whole Drosophila larvae. SEBP1 binds to a single site within the Pig-1/Sgs-4 intergenic region. Point mutations that disrupt this site had no significant effect on activation of the Sgs-4 promoter in constructs lacking the Pig-1 promoter. However, if the Pig-1 promoter was present, the same mutations led to a strong attenuation of Sgs-4 promoter activity, suggesting that binding of SEBP1 is necessary for the Pig-1/Sgs-4 transcriptional switch. The data are consistent with a model in which the SEBP1 binding site acts as a transient silencing element that facilitates the reorganization of promoter-enhancer interactions by disrupting pre-existing interactions, thus enabling stage-specific activators of Sgs-4 to bind to their enhancer target sites.
    Type of Medium: Electronic Resource
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