نتایج جستجو برای: pulse strength threshold
تعداد نتایج: 410091 فیلتر نتایج به سال:
With their short nanosecond pulse durations, Qswitched lasers have revolutionized the treatment of tattoos [1-3]. Nevertheless, the mechanisms for clinically observed tattoo clearance are still not well understood. Two mechanisms have been proposed: a) a thermal effect where tattoo particles are heated to sufficiently high temperatures to cause chemical changes within the particles and the surr...
High-energy and short-duration laser pulses are desirable to improve the photoacoustic image quality when imaging deeply seated lesions. In many clinical applications, the high-energy pulses are coupled to tissue using optical fibers. These pulses can damage fibers if the damage threshold is exceeded. While keeping the total energy under the Food and Drug Administration limit for avoiding tissu...
Aerobic exercise training increases arterial compliance and reduces systolic blood pressure, but the effects of muscular strength training on arterial mechanical properties are unknown. We compared blood pressure, whole body arterial compliance, aortic impedance, aortic stiffness (measured by beta-index and carotid pulse pressure divided by normalized systolic expansion [Ep]), pulse wave veloci...
8.1 Historical Background 8.2 Theory of Wave Propagation 8.3 Pulse Velocity Test Instrument 8.4 The Pulse Velocity Method 8.5 Factors Affecting Pulse Velocity Effects of Concrete Properties • Other Effects • Temperature of Concrete 8.6 Standardization of the Pulse Velocity Method 8.7 Applications Estimation of Strength of Concrete • Establishing Homogeneity of Concrete • Studies on the Hydratio...
The high current and ESD effects on VLSI interconnect metallization have been characterized and a model for heating under ESD conditions is presented. I t is shown that thermal breakdown occurs when the resistances increase by a factor of >3.6 due to melting of metal lines. After the metal is molten, the thermal stress is required to exceed the fracture strength of the oxidelnitride layers in o...
The EGF-stimulated ERK/MAPK pathway is a key conduit for cellular proliferation signals and a therapeutic target in many cancers. Here, we characterize two central quantitative aspects of this pathway: the mechanism by which signal strength is encoded and the response curve relating signal output to proliferation. Under steady-state conditions, we find that ERK is activated in discrete, asynchr...
Training of spinal cord circuits using sensorimotor stimulation has been proposed as a strategy to improve movement after spinal injury. How sensory stimulation may lead to long-lasting changes is not well understood. We studied whether sensory stimulation might induce changes in the strength of a specific spinal interneuronal circuit: spinally mediated reciprocal Ia inhibition. In healthy huma...
We discuss the dynamics of ultrashort pulsed laser excitation in bulk optical silica-based glasses (fused silica and borosilicate BK7) well-above the permanent modification threshold. We indicate subsequent structural and thermomechanical energy relaxation paths that translate into positive and negative refractive index changes, compression and rarefaction zones. If fast electronic decay occurs...
OBJECTIVES To evaluate the stimulation effectiveness of different magnetic stimulator devices with respect to pulse waveform and current direction in the motor cortex. METHODS In 8 normal subjects we determined motor thresholds of transcranial magnetic stimulation in a small hand muscle. We used focal figure-of-eight coils of 3 common stimulators (Dantec Magpro, Magstim 200 and Magstim Rapid)...
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