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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 67-68 (Apr. 1999), p. 565-570 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of volcanology 61 (1999), S. 162-173 
    ISSN: 1432-0819
    Keywords: Key words Pyroclast types ; Methodological approach ; Modal analysis ; Eruption style ; Compositional indices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  This paper illustrates some problems involved in the quantitative compositional study of pyroclastic deposits and proposes criteria for selecting the main petrographic and textural classes for modal analysis. The relative proportions of the different classes are obtained using a point-counting procedure applied to medium-coarse ash samples that reduces the dependence of the modal composition on grain size and avoids tedious counting of different grain-size fractions. The major purposes of a quantified measure of component distributions are to: (a) document the nature of the fragmenting magma; (b) define the eruptive dynamics of the eruptions on a detailed scale; and (c) ensure accuracy in classifying pyroclastic deposits. Compositional modes of the ash fraction of pyroclastic deposits vary systematically, and their graphical representation defines the compositional and textural characteristics of pyroclastic fragments associated with different eruptive styles. Textural features of the glass component can be very helpful for inferring aspects of eruptive dynamics. Four major parameters can be used to represent the component composition of pyroclastic ash deposits: (a) juvenile index (JI); (b) crystallinity index (CrI); (c) juvenile vesicularity index (JVI); and (d) free crystal index (FCrI). The FCrI is defined as the ratio between single and total crystal fragments in the juvenile component (single crystals+crystals in juvenile glass). This parameter may provide an effective estimate of the mechanical energy of eruptions. Variations in FCrI vs JVI discriminate among pyroclastic deposits of different origin and define compositional fields that represent ash derived from different fragmentation styles.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0942-0940
    Keywords: Keywords: Cerebral palsy; spasticity; rhizotomy; limited selective rhizotomy.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary  Selective posterior rhizotomy is effective for relieving spasticity associated with cerebral palsy. In current techniques dorsal roots from L1/L2 to S1/S2 are selectively divided. With transoperative electromyography (EMG) significant sensory loss has been prevented, but postoperative hypotonia following excessive reduction of the fusimotor drive is still of concern for surgeons and therapists. To decrease the volume of deafferentiated rootlets we proposed a limited selective posterior rhizotomy (LPSR) that limits the extent of the surgery to three (L4-S1) or two (L5-S1) dorsal roots. We present the results of two group of spastic children; group 1 (n=59, 32 quadriplegic and 27 diplegic) who had a L4-S1 LPSR. and group 2 (n=12) in whom L5 and S1 were selectively rhizotomized. Posture, passive movilization, range of joint movement, and muscle tone in hip flexors, adductors, leg flexors and plantar flexors were graded according to the method proposed by Sindou and Jeanmonod. In all groups there was a significant reduction of the mentioned parameters (Friedman test p〈0.001) at 6, 12 and 18 months after surgery. The preoperative and postoperative ability to ambulate was classified into five grades. In all groups there was a significant (χ2 between p〈0.01 and p〈0.001) improvement in the quality of their gait. A third of the patients achieved some form of independent ambulation. Our results suggest that extensive selective deafferentation of the lower limbs is not an absolute requisite for reducing muscle tone or achieving functional improvement in spastic children.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0819
    Keywords: Key words Explosive hydromagmatic eruptions ; Fine-grained massive layers ; Turbulent flows ; Vulcano
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Tufi di Grotte dei Rossi Inferiori are thick ash deposits, representing the most voluminous stratigraphic unit on Vulcano Island. The deposits are related to hydromagmatic eruption which occurred under shallow water inside a caldera depression. Grain-size data and results of SEM investigation allow the character of the transporting medium, solid material concentration in the cloud during the lateral expansion, and the nature and role of the fluids present at the time of deposition to be constrained. We suggest that the eruption was characterized by closely timed hydromagmatic pulses giving rise to eruption clouds rich in water vapor and steam. The coarser material was not significantly transported in the eruptive cloud and it probably deposited in the caldera depression area. The finer material was extensively transported in the cloud, creating turbulent flows which surmounted the caldera rim barrier and dispersed in a southward direction, forming widespread deposits in the Piano area. Lower concentrated flows produced laminated deposits of more limited dispersion, whereas higher concentrated flows formed more dispersed thicker massive layers.
    Type of Medium: Electronic Resource
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