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  • 1
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    Gravity currents flowing upslope: Laboratory experiments and shallow-water simulations (2015)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2015-01-15
    Description: This paper investigates the dynamics of lock-release gravity currents propagating upslope by laboratory experiments and shallow-water simulations. Both the interface between the dense and the ambient fluid and the instantaneous velocity field were measured by image analysis. Different runs were carried out by varying the initial density of the lock fluid and the bed upslope. As a gravity current moves upslope, the dense layer becomes thinner, and an accumulation region of dense fluid in the initial part of the tank occurs. The current speed decreases as the bed upslope increases, and for the highest up sloping angles, the gravity current stops before reaching the end of the tank. A new two-layer shallow-water model is developed and benchmarked against laboratory experiments. The present model accounts for the mixing between the two layers, the free surface, and the space-time variations of the density. The effect of the horizontal density gradient in the simulation of gravity currents is investigated by comparing the numerical results of both the present model and the model proposed by Adduce et al. [“Gravity currents produced by lock-exchange: Experiments and simulations with a two layer shallow-water model with entrainment,” J. Hydraul. Eng. 138 , 111-121 (2012)] with laboratory measurements. The comparison shows that the present model reproduces both the current shape and the front position better than the Adduce et al. model, in particular, for gravity currents flowing up a slope. For these currents, the presence of a backflow near the lock is shown by the analysis of the streamwise depth-averaged velocity predicted by the present model and the velocity measured by particle image velocimetry as well.
    Print ISSN: 1070-6631
    Electronic ISSN: 1089-7666
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 2
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    Force generation by skeletal muscle is controlled by mechanosensing in myosin filaments (2015)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2015-11-13
    Description: Contraction of both skeletal muscle and the heart is thought to be controlled by a calcium-dependent structural change in the actin-containing thin filaments, which permits the binding of myosin motors from the neighbouring thick filaments to drive filament sliding. Here we show by synchrotron small-angle X-ray diffraction of frog (Rana temporaria) single skeletal muscle cells that, although the well-known thin-filament mechanism is sufficient for regulation of muscle shortening against low load, force generation against high load requires a second permissive step linked to a change in the structure of the thick filament. The resting (switched 'OFF') structure of the thick filament is characterized by helical tracks of myosin motors on the filament surface and a short backbone periodicity. This OFF structure is almost completely preserved during low-load shortening, which is driven by a small fraction of constitutively active (switched 'ON') myosin motors outside thick-filament control. At higher load, these motors generate sufficient thick-filament stress to trigger the transition to its long-periodicity ON structure, unlocking the major population of motors required for high-load contraction. This concept of the thick filament as a regulatory mechanosensor provides a novel explanation for the dynamic and energetic properties of skeletal muscle. A similar mechanism probably operates in the heart.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Linari, Marco -- Brunello, Elisabetta -- Reconditi, Massimo -- Fusi, Luca -- Caremani, Marco -- Narayanan, Theyencheri -- Piazzesi, Gabriella -- Lombardi, Vincenzo -- Irving, Malcolm -- England -- Nature. 2015 Dec 10;528(7581):276-9. doi: 10.1038/nature15727. Epub 2015 Nov 11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Physiology, Department of Biology, Universita di Firenze, Sesto Fiorentino, 50019 Florence, Italy. ; Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, UdR Firenze, Sesto Fiorentino, 50019 Florence, Italy. ; Randall Division and BHF Centre for Research Excellence, King's College London, London SE1 1UL, UK. ; European Synchrotron Radiation Facility, BP220, F-38043 Grenoble, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26560032" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Male ; Mechanotransduction, Cellular/*physiology ; Muscle, Skeletal/*metabolism ; Myosins/*metabolism ; Rana temporaria ; Synchrotrons ; Time Factors ; X-Ray Diffraction
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 3
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    Effects of Particle Size and Density on the Packed-Bed Pyrolysis of Wood (2013)
    American Chemical Society (ACS)
    Details
    Publication Date: 2013-11-01
    Description: Energy & Fuels DOI: 10.1021/ef401481j
    Print ISSN: 0887-0624
    Electronic ISSN: 1520-5029
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Process Engineering, Biotechnology, Nutrition Technology
    Published by American Chemical Society (ACS)
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  • 4
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    Erratum: “Gravity currents flowing upslope: Laboratory experiments and shallow-water simulations” [Phys. Fluids 27, 016602 (2015)] (2015)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2015-08-21
    Print ISSN: 1070-6631
    Electronic ISSN: 1089-7666
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 5
    Electronic Resource
    Electronic Resource
    New acrylic-allylic resins containing perfluoropolyether chains for UV-cured coatings (1999)
    Bingley : Emerald
    Pigment & resin technology 28 (1999), S. 212-216 
    Details
    ISSN: 0369-9420
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: New acrylic and allylic resins were prepared by functionalising perfluoropolyethers chains, which assured peculiar surface properties. Blends having a different amount of the acrylic and of the allylic systems were cured in air by UV irradiation. The cure of the films was found dependent on the ratio between the two resins; the concentration for the obtaining of a film fully cured in air was determined. On the basis of this concentration, a macromer functionalised with the right amount of both the acrylic group and the allylic one was synthesised.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/EUM0000000004613
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  • 6
    Electronic Resource
    Electronic Resource
    Overt and latent HIV 1 and HTLV-I infection in cohorts of at high risk individuals in Argentina
    Amsterdam : Elsevier
    Molecular and Cellular Probes 5 (1991), S. 409-417 
    Details
    ISSN: 0890-8508
    Keywords: [Keyword] HIV 1 ; [Keyword] HTLV-I latent infection ; [Keyword] polymerase chain reaction (PCR) ; [Keyword] proviral sequences
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0890-8508(05)80012-X
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  • 7
    Electronic Resource
    Electronic Resource
    Development of force-velocity relation, stiffness and isometric tension in frog single muscle fibres (1983)
    Springer
    Journal of muscle research and cell motility 4 (1983), S. 177-189 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The force-velocity (T-V) relation and the force-extension (T 1) relation from single fibres isolated from the muscle tibialis anterior of the frog were determined at preset times during the rise of tension and the plateau of an isometric tetanus. During the rise of an isometric tetanus the value of V0 (the velocity of shortening at zero load) remained constant, whereas both the forceT exerted during shortening at a given velocity lower than V0 and the slope of the instantaneousT 1 curve increased with time after the beginning of the stimulus volley. However, while the value ofT (a measure of the level of activation) attained its final value much before the isometric tension attained the plateau, the slope of theT 1 curve (the fibre stiffness, a measure of the number of attached crossbridges) increased throughout the course of tension development. In six muscle fibres, at 2.25µm sarcomere length and at about 4° C, at a time during the tetanus rise whenT had attained 81% of its final value, the fibre stiffness and the isometric tension had risen, respectively, to 50% and to 38% of the values attained at the tetanus plateau. Later, whenT had already attained 99% of its final value, the fibre stiffness and the isometric tension had risen, respectively, to 80% and to 76% of their plateau values. In the same muscle fibres, the average value for the amount of step release required to drop the plateau tetanic tension to zero was only 8.62 nm (observed) or 6.16 nm (extrapolated from the linear part of theT 1 curves) per half sarcomere. It is concluded that the large delay in the development of the isometric tension with respect to the development ofT, and therefore with respect to the development of the wholeT-V relation, cannot be attributed to the passive series compliance of the muscle fibres. It is likely that this delay is due to a specific event in the contractile process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00712029
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  • 8
    Electronic Resource
    Electronic Resource
    The maximum velocity of shortening during the early phases of the contraction in frog single muscle fibres (1984)
    Springer
    Journal of muscle research and cell motility 5 (1984), S. 503-513 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The maximum velocity of shortening (V max) was determined at preset times during the development and the plateau of isometric tetani in single fibres isolated from the tibialis anterior muscle of the frog. Experiments were performed at low temperature (3.6–6° C) and at about 2.25 µm sarcomere length. The controlled velocity release method was used.V max was measured by determining the lowest velocity of release required to keep the tension at zero. Extreme care was taken in dissection and mounting of the fibres in order to make the passive series compliance very small. The value ofV max at the end of the latent period for the development of isometric tension (at 4.5° C about 10 ms after the beginning of the stimulus volley) was already the same as later during either the tension rise or at the plateau of isometric tetani. These results show that the value ofV max of intact fibres is independent of time and activation subsequent to the latent period, and suggest that the cycling rate of the crossbridges may thus attain its steady-state value just at the end of the isometric latent period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00713257
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  • 9
    Electronic Resource
    Electronic Resource
    1H NMR Ganglioside Ceramide Resonance Region on the Differential Diagnosis of Low and High Malignancy of Brain Gliomas (1997)
    Springer
    Cellular and molecular neurobiology 17 (1997), S. 521-535 
    Details
    ISSN: 1573-6830
    Keywords: brain gliomas ; ceramide ; ganglioside ; malignancy ; 1H NMR spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. The high-resolution 1H NMR (MRS) spectra of human brain tumor homogenates revealed a broad resonance at 5.3–5.4 ppm in glioblastoma multiforme (N = 16) and brain metastases (N = 2). The broad resonance was identified as ceramide, a sphingosine–fatty acid combination portion of ganglioside, indicating an elevated abundance of monounsaturated fatty acids. GLC analysis of gangliosides in the highly malignant glioblastoma multiforme revealed that the elevated monounsaturated fatty acid is oleic acid (C18:1). The resonance at 5.3–5.4 ppm region was not detectable in normal human brain (N = 2), in meningiomas (N = 2), or in low-grade astrocytomas (N = 12). In normal human brain the abundance of monounsaturated fatty acid is minimal. 2. This investigation was made possible because the method of producing homogenate resulted in (i) no loss of lipids during the process and (ii) a well-homogenised sample, with (iii) no loss in chemical integrity. 3. The properties of tumor gangliosides include antigenic specificity and immunosuppresive activity and the ceramide, a sphingosine–fatty acid combination, noticeably influences the ganglioside immunosuppressive activity. 4. The observation of 1H NMR ceramide resonance in high-malignant brain tumors emphasizes the dramatic role of aberrant gangliosides and ceramide precursors on the grade of malignancy and invasiveness. 5. Further insight into the specific nature of the ceramide portion of gangliosides in grading the malignancy of brain tumors should be investigated further.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026362922549
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  • 10
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    Interference fine structure and sarcomere length dependence of the axial x-ray pattern from active single muscle fibers (2000)
    National Academy of Sciences
    Details
    Publication Date: 2000-06-20
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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