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  • 11
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 1311-1316 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A quantitative model is proposed to elucidate and predict the dome-shaped surface topography resulting from CO2 laser heating of glass substrates. In the analysis, a permanent structural change in glass is induced by a higher glass transition temperature due to the faster cooling process, with a final topography being determined by the temperature history resulting from the absorbed laser energy. The analysis is validated by experiment, which focuses on the energies which trigger the permanent deformation and induce a dome-shaped topography. The dimensions (maximum height and base area) of the bump show a logarithmic dependence on energy as expected from the theory. Using the constants determined from the experimental data and our analysis, bump profiles over a range of laser fluences are predicted. These two constants provide the information for determining the new glass transition temperature and the threshold energy needed to form a permanent bump. The result also suggests that the topography is mostly determined from the conditions at the end of the laser pulse. The effects of thermally induced stress on the model, and the physics of bump formation in chemically strengthened glass are addressed. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 11 (1999), S. 1512-1520 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using a novel numerical method at unprecedented resolution, we demonstrate that structures of small to intermediate scale in rotating, stratified flows are intrinsically three-dimensional. Such flows are characterized by vortices (spinning volumes of fluid), regions of large vorticity gradients, and filamentary structures at all scales. It is found that such structures have predominantly three-dimensional dynamics below a horizontal scale L(approximate)〈fraction SHAPE="CASE"〉12LR, where LR is the so-called Rossby radius of deformation, equal to the characteristic vertical scale of the fluid H divided by the ratio of the rotational and buoyancy frequencies f/N. The breakdown of two-dimensional dynamics at these scales is attributed to the so-called "tall-column instability" [D. G. Dritschel and M. de la Torre Juárez, J. Fluid. Mech. 328, 129 (1996)], which is active on columnar vortices that are tall after scaling by f/N, or, equivalently, that are narrow compared with LR. Moreover, this instability eventually leads to a simple relationship between typical vertical and horizontal scales: for each vertical wave number (apart from the vertically averaged, barotropic component of the flow) the average horizontal wave number is equal to f/N times the vertical wave number. The practical implication is that three-dimensional modeling is essential to capture the behavior of rotating, stratified fluids. Two-dimensional models are not valid for scales below LR. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 4852-4858 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Picosecond interferometry is used to study the acoustics waves created by heating Pt films with a subpicosecond laser pulse. Both the period of the initial oscillations in the metal film and the amplitude of the sound wave in the substrate are measured quantitatively. The platinum films are roughened by irradiation with energetic ions. The amplitude of the sound wave is doubled at those irradiation levels where the platinum coverage has been reduced by about one-half. A theory for the amplitude of the launched acoustic wave predicts that the acoustic amplitude is proportional to the mean square film thickness. Thus changes in the morphology of a partially perforated metal film can be observed using a simple, nondestructive optical technique. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 4282-4285 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The methodology for accurately calibrating the Niobe resonant-mass gravitational wave detector is presented. The transducer is based on a low noise resonant microwave cavity transducer that converts the displacement of the resonating mass to microwave energy. The calibration technique consists of a one off measurement of the microwave frequency versus resonant-mass displacement characteristic. To measure this accurately, known static forces were applied to the resonant mass and the change in the transducer microwave frequency was recorded. With the aid of finite element analysis and accurate measurements of the resonant-mass characteristics, the deflection due to the known force was calculated. The calculated deflections were verified coarsely with measurements from a calibrated linear variable differential transformer. Typically, the detector operates with a 1 mK noise temperature. A best noise temperature of 890 μK between 1300 and 2000 Universal Time Coordinate (UTC) for day 60 in 1997 is reported. The transducer has been upgraded with a new microwave amplifier, which has a measured electronic noise floor 40 dB lower than the previous amplifier, which is only 10 dB above the quantum limit. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 1974-1977 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a simple method for creating multiple optical tweezers from a single laser beam using diffractive optical elements. As a demonstration of this technique, we have implemented a 4×4 square array of optical tweezers—the hexadeca tweezer. Not only will diffractively generated optical tweezers facilitate many new experiments in pure and applied physics, but they also will be useful for fabricating nanocomposite materials and devices, including photonic bandgap materials and optical circuit elements. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Inc
    Wound repair and regeneration 12 (2004), S. 0 
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Inc
    Wound repair and regeneration 12 (2004), S. 0 
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    Wound repair and regeneration 8 (2000), S. 0 
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In a healing wound, inflammatory cells undergo apoptosis immediately beneath the leading edge of migrating epithelium. A potential mediator of this apoptosis pattern is p53, a protein with antiproliferative effects. Another protein, bcl-2, is antagonistic to p53 and prevents apoptosis. The purpose of this study was to determine the expression and location of p53 and bcl-2 mRNA and protein in healing wounds of normal and genetically diabetic mice. At various time points, full-thickness skin wounds from nondiabetic and diabetic mice were evaluated for p53 and bcl-2 by immunohistochemistry and in situ hybridization. Apoptosis patterns were also determined using the TUNEL method. Messenger RNA for p53 and bcl-2 were quantitated by competitive reverse transcriptase-polymerase chain reaction. Protein and mRNA for p53 were expressed in the leading edge of migrating epithelium, with apoptosis patterns closely following those of p53 production. p53 mRNA levels decreased soon after wounding, but after a few days, levels increased to greater than baseline. bcl-2 was localized to the wound epithelium, but relative amounts tended to oppose levels of p53, i.e, when p53 increased, bcl-2 decreased and vice versa. Wounds in diabetic animals showed a delayed onset of p53 mRNA expression but had persistently greater levels for longer periods of time. bcl-2 mRNA expression was further delayed in diabetic mice and did not develop to levels as high as p53. Production of both proteins was delayed, consistent with the mRNA expression. Our data show that immediately after wounding, bcl-2 increases and p53 decreases to allow for the cellular proliferation that is required for tissue repair. Over time, bcl-2 levels decrease while p53 levels increase to shut down the inflammatory process and down-regulate the proliferative response. Diabetic animals appear to lose the indirect relationship between p53 and bcl-2. This loss may contribute to the altered apoptosis patterns observed in diabetic healing.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science
    Wound repair and regeneration 5 (1997), S. 0 
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Wound healing is the result of a dynamic balance between synthetic and degradative processes. After a burn, proteolytic activity increases at the wound site. Excised burn wounds and donor skin were examined from 20 pediatric burn patients, to determine which of two classes of neutral proteinases, serine or metalloproteinases, accounts for the majority of this proteolytic activity in these tissues; to examine messenger RNA expression of three of the principal enzymes and inhibitors of this class; and to measure enzymatic activity of two of these metalloproteinases. The majority of the increased proteolysis was due to metalloproteinases. By polymerase chain reaction assays, messenger RNAs for matrix metalloproteinase-1, -3, and -9 were strongly expressed in burn tissue and absent or weakly expressed in unburned skin. Messenger RNA for tissue inhibitor of metalloproteinase-1 and -2 was consistently present in burned and unburned skin. By zymography, there was a significant increase in matrix metalloproteinase-2 (twofold to threefold) and matrix metalloproteinase-9 (20- to 30-fold) activity in burned versus unburned skin. We suggest that postburn there is an upregulation of some matrix metalloproteinases that exceeds the level of inhibitors with the net result of an increase in proteolysis in burned tissue. This increased proteolysis may play a role in wound repair and scar formation.
    Type of Medium: Electronic Resource
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  • 20
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Restoration of the epidermal barrier is a requirement for burn wound closure. A rapid, reliable, and noninvasive measure of the rate of restoration of the epidermal barrier is not readily available. To monitor the reformation of the epidermal barrier, we measured surface electrical capacitance on cultured skin substitutes (human keratinocytes and fibroblasts attached to collagen-glycosaminoglycan substrates) and split-thickness skin autografts grafted to patients. Data were collected from four patients with burns and one pediatric patient with a congenital hairy nevus comprising 〉 60% total body surface area. Capacitance measurements were performed at days 7, 10, 12, 14, and 28 by direct contact of the capacitance probe for 10 seconds to the cultured skin substitutes or split-thickness autograft. On postoperative days 7, 10, 12, 14, 21, and 28, the surface electrical capacitance of cultured skin substitutes after 10 seconds of sampling was 2468 ± 268, 1443 ± 439, 129 ± 43, 200 ± 44, 88 ± 20, and 74 ± 19 picofarads (mean ± standard error of the mean), respectively. Surface electrical capacitance for split-thickness autograft on the same days was 1699 ± 371, 1914 ± 433, 125 ± 16, 175 ± 63, 110 ± 26, 271 ± 77 picofarads, respectively. Surface electrical capacitance in all of the grafts decreased with time. Cultured skin substitutes had approximately the same 10-second capacitance values as split-thickness autograft during 3 weeks of healing and approached values for uninjured skin (32 ± 5 picofarads) by 12 days. Measurement of surface electrical capacitance is a direct, inexpensive, and convenient index for noninvasive monitoring of epidermal barrier formation.
    Type of Medium: Electronic Resource
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