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Ultrasonic acoustic fields have recently been used to generate haptic effects on the human skin as well as to levitate small sub-wavelength size particles. Schlieren imaging and background-oriented schlieren techniques can be used for acoustic wave pattern and beam shape visualization. These techniques exploit variations in the refractive index of a propagation medium by applying refractive optics or cross-correlation algorithms of photographs of illuminated background patterns. Here both background-oriented and traditional schlieren systems are used to visualize the regions of the acoustic power involved in creating dynamic haptic sensations and dynamic levitation traps. We demonstrate for the first time the application of back-ground-oriented schlieren for imaging ultrasonic fields in air. We detail our imaging apparatus and present improved algorithms used to visualize these phenomena that we have produced using multiple phased arrays. Moreover, to improve imaging, we leverage an electronically controlled, high-output LED which is pulsed in synchrony with the ultrasonic carrier frequency., Comment: 9 pages, 7 figures

This report considers a number of selected areas of security technology and practice. The focus is on exposing and highlighting research gaps and opportunities in the current security state of the art within these areas, both in terms of implementation practice and of the literature.

Writing can be among the most mercurial of skills, in large measure because of how quickly clarity can slip through one's fingers. The Hemingway Editor provides a distraction-free writing environment with a twist. It has an Edit mode that will highlight complex sentences and common errors, compute readability scores, and estimate reading time. According to the about page, "It's like a spell checker, but for style." These features can help authors to sharpen, clarify, and simplify their prose. In addition to the free web version of the editor, a desktop version is available for purchase for both Macintosh and Windows computers.

Writing can be among the most mercurial of skills, in large measure because of how quickly clarity can slip through one's fingers. The Hemingway Editor provides a distraction-free writing environment with a twist. It has an Edit mode that will highlight complex sentences and common errors, compute readability scores, and estimate reading time. According to the about page, "It's like a spell checker, but for style." These features can help authors to sharpen, clarify, and simplify their prose. In addition to the free web version of the editor, a desktop version is available for purchase for both Macintosh and Windows computers.