An Audible Demonstration Of The Speed Of Sound In Bubbly Liquids

The speed of sound in a bubbly liquid is strongly dependent upon the volume fraction of the gas phase, the bubble size distribution, and the frequency of the acoustic excitation. At sufficiently low frequencies, the speed of sound depends primarily on the gas volume fraction. This effect can be audibly demonstrated using a one-dimensional acoustic waveguide, in which the flow rate of air bubbles injected into a water-filled tube is varied by the user. The normal modes of the waveguide are excited by the sound of the bubbles being injected into the tube. As the flow rate is varied, the speed of sound varies as well, and hence, the resonance frequencies shift. This can be clearly heard through the use of an amplified hydrophone and the user can create aesthetically pleasing and even musical sounds. In addition, the apparatus can be used to verify a simple mathematical model known as Wood's equation that relates the speed of sound of a bubbly liquid to its void fraction. (c) 2008 American Association of Physics Teachers.Mechanical Engineerin

Which learning activities enhance physical therapist practice? Part 1: Systematic review and meta-analysis of quantitative studies

Objective. Following graduation from professional education, the development of clinical expertise requires career-long participation in learning activities. The purpose of study was to evaluate which learning activities enhanced physical therapist practice. Methods. Eight databases were searched for studies published from inception through December 2018. Articles reporting quantitative data evaluating the effectiveness of learning activities completed by qualified physical therapists were included. Study characteristics and results were extracted from the 26 randomized controlled trials that met the inclusion criteria. Clinician (knowledge, affective attributes, and behavior) and patient related outcomes were extracted. Results: There was limited evidence that professional development courses improved physical therapist knowledge. There was low-level evidence that peer assessment and feedback was more effective than case discussion at improving knowledge (SMD = 0.35, 95%CI = 0.09-0.62). Results were inconsistent for the effect of learning activities on affective attributes. Courses with active learning components appeared more effective at changing physical therapist behavior. The completion of courses by physical therapists did not improve patient outcomes; however, the addition of a mentored patient interaction appeared impactful. Conclusions. Current evidence suggests active approaches, such as peer assessment and mentored patient interactions, should be used when designing learning activities for physical therapists. Further high-quality research focused on evaluating the impact of active learning interventions on physical therapist practice and patient outcomes is now needed. Impact. This study is a first step in determining which learning activities enhance clinical expertise and practice would enable the physical therapy profession to make informed decisions about the allocation of professional development resources

Holograms to Focus Arbitrary Ultrasonic Fields through the Skull

[EN] We report 3D-printed acoustic holographic lenses for the formation of ultrasonic fields of complex spatial distribution inside the skull. Using holographic lenses, we experimentally, numerically and theoretically produce acoustic beams whose spatial distribution matches target structures of the central nervous system. In particular, we produce three types of targets of increasing complexity. First, a set of points are selected at the center of both right and left human hippocampi. Experiments using a skull phantom and 3D printed acoustic holographic lenses show that the corresponding bi-focal lens simultaneously focuses acoustic energy at the target foci, with good agreement between theory and simulations. Second, an arbitrary curve is set as the target inside the skull phantom. Using time-reversal methods the holographic beam bends following the target path, in a similar way as self-bending beams do in free space. Finally, the right human hippocampus is selected as a target volume. The focus of the corresponding holographic lens overlaps with the target volume in excellent agreement between theory in free-media, and experiments and simulations including the skull phantom. The precise control of focused ultrasound into the central nervous system is mainly limited due to the strong phase aberrations produced by refraction and attenuation of the skull. Using the present method, the ultrasonic beam can be focused not only at a single point but overlapping one or various target structures simultaneously using low-cost 3D-printed acoustic holographic lens. The results open new paths to spread incoming biomedical ultrasound applications including blood-brain barrier opening and neuromodulation.This work is supported by the Spanish Ministry of Economy and Innovation (MINECO) through Project No. TEC2016-80976-R. N.J. and S.J. acknowledge financial support from Generalitat Valenciana through Grants No. APOSTD/2017/042, No. ACIF/2017/045, and No. GV/2018/11. F.C. acknowledges financial support from Agencia Valenciana de la Innovacio through Grant No. INNCON00/18/9 and European Regional Development Fund (Grant No. IDIFEDER/2018/022).Jiménez-Gambín, S.; Jimenez, N.; Benlloch Baviera, JM.; Camarena Femenia, F. (2019). Holograms to Focus Arbitrary Ultrasonic Fields through the Skull. Physical Review Applied. 12(1):014016-1-014016-14. https://doi.org/10.1103/PhysRevApplied.12.014016S014016-1014016-14121GABOR, D. (1948). A New Microscopic Principle. Nature, 161(4098), 777-778. doi:10.1038/161777a0Microscopy by reconstructed wave-fronts. (1949). Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 197(1051), 454-487. doi:10.1098/rspa.1949.0075Leith, E. N., & Upatnieks, J. (1962). Reconstructed Wavefronts and Communication Theory*. Journal of the Optical Society of America, 52(10), 1123. doi:10.1364/josa.52.001123Ni, X., Kildishev, A. V., & Shalaev, V. M. (2013). Metasurface holograms for visible light. Nature Communications, 4(1). doi:10.1038/ncomms3807Huang, L., Chen, X., Mühlenbernd, H., Zhang, H., Chen, S., Bai, B., … Zhang, S. (2013). Three-dimensional optical holography using a plasmonic metasurface. Nature Communications, 4(1). doi:10.1038/ncomms3808Ma, G., & Sheng, P. (2016). Acoustic metamaterials: From local resonances to broad horizons. Science Advances, 2(2), e1501595. doi:10.1126/sciadv.1501595Cummer, S. A., Christensen, J., & Alù, A. (2016). Controlling sound with acoustic metamaterials. Nature Reviews Materials, 1(3). doi:10.1038/natrevmats.2016.1Liu, Z. (2000). Locally Resonant Sonic Materials. Science, 289(5485), 1734-1736. doi:10.1126/science.289.5485.1734Fang, N., Xi, D., Xu, J., Ambati, M., Srituravanich, W., Sun, C., & Zhang, X. (2006). Ultrasonic metamaterials with negative modulus. Nature Materials, 5(6), 452-456. doi:10.1038/nmat1644Yang, M., Ma, G., Yang, Z., & Sheng, P. (2013). Coupled Membranes with Doubly Negative Mass Density and Bulk Modulus. Physical Review Letters, 110(13). doi:10.1103/physrevlett.110.134301Li, Y., Liang, B., Gu, Z., Zou, X., & Cheng, J. (2013). Reflected wavefront manipulation based on ultrathin planar acoustic metasurfaces. Scientific Reports, 3(1). doi:10.1038/srep02546Xie, Y., Wang, W., Chen, H., Konneker, A., Popa, B.-I., & Cummer, S. A. (2014). Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface. Nature Communications, 5(1). doi:10.1038/ncomms6553Jiménez, N., Cox, T. J., Romero-García, V., & Groby, J.-P. (2017). Metadiffusers: Deep-subwavelength sound diffusers. Scientific Reports, 7(1). doi:10.1038/s41598-017-05710-5Jiménez, N., Romero-García, V., Pagneux, V., & Groby, J.-P. (2017). Rainbow-trapping absorbers: Broadband, perfect and asymmetric sound absorption by subwavelength panels for transmission problems. Scientific Reports, 7(1). doi:10.1038/s41598-017-13706-4Qi, S., Li, Y., & Assouar, B. (2017). Acoustic Focusing and Energy Confinement Based on Multilateral Metasurfaces. Physical Review Applied, 7(5). doi:10.1103/physrevapplied.7.054006Bok, E., Park, J. J., Choi, H., Han, C. K., Wright, O. B., & Lee, S. H. (2018). Metasurface for Water-to-Air Sound Transmission. Physical Review Letters, 120(4). doi:10.1103/physrevlett.120.044302Li, Y., Jiang, X., Liang, B., Cheng, J., & Zhang, L. (2015). Metascreen-Based Acoustic Passive Phased Array. Physical Review Applied, 4(2). doi:10.1103/physrevapplied.4.024003Li, Y., & Assouar, M. B. (2015). Three-dimensional collimated self-accelerating beam through acoustic metascreen. Scientific Reports, 5(1). doi:10.1038/srep17612Kaina, N., Lemoult, F., Fink, M., & Lerosey, G. (2015). Negative refractive index and acoustic superlens from multiple scattering in single negative metamaterials. Nature, 525(7567), 77-81. doi:10.1038/nature14678Li, J., Fok, L., Yin, X., Bartal, G., & Zhang, X. (2009). Experimental demonstration of an acoustic magnifying hyperlens. Nature Materials, 8(12), 931-934. doi:10.1038/nmat2561Melde, K., Mark, A. G., Qiu, T., & Fischer, P. (2016). Holograms for acoustics. Nature, 537(7621), 518-522. doi:10.1038/nature19755Xie, Y., Shen, C., Wang, W., Li, J., Suo, D., Popa, B.-I., … Cummer, S. A. (2016). Acoustic Holographic Rendering with Two-dimensional Metamaterial-based Passive Phased Array. Scientific Reports, 6(1). doi:10.1038/srep35437Zhu, Y., Hu, J., Fan, X., Yang, J., Liang, B., Zhu, X., & Cheng, J. (2018). Fine manipulation of sound via lossy metamaterials with independent and arbitrary reflection amplitude and phase. Nature Communications, 9(1). doi:10.1038/s41467-018-04103-0Memoli, G., Caleap, M., Asakawa, M., Sahoo, D. R., Drinkwater, B. W., & Subramanian, S. (2017). Metamaterial bricks and quantization of meta-surfaces. Nature Communications, 8(1). doi:10.1038/ncomms14608Brown, M. D., Cox, B. T., & Treeby, B. E. (2017). Design of multi-frequency acoustic kinoforms. Applied Physics Letters, 111(24), 244101. doi:10.1063/1.5004040Hertzberg, Y., & Navon, G. (2011). Bypassing absorbing objects in focused ultrasound using computer generated holographic technique. Medical Physics, 38(12), 6407-6415. doi:10.1118/1.3651464Zhang, P., Li, T., Zhu, J., Zhu, X., Yang, S., Wang, Y., … Zhang, X. (2014). Generation of acoustic self-bending and bottle beams by phase engineering. Nature Communications, 5(1). doi:10.1038/ncomms5316Marzo, A., Seah, S. A., Drinkwater, B. W., Sahoo, D. R., Long, B., & Subramanian, S. (2015). Holographic acoustic elements for manipulation of levitated objects. Nature Communications, 6(1). doi:10.1038/ncomms9661Ter Haar, >Gail, & Coussios, C. (2007). High intensity focused ultrasound: Physical principles and devices. International Journal of Hyperthermia, 23(2), 89-104. doi:10.1080/02656730601186138Gélat, P., ter Haar, G., & Saffari, N. (2014). A comparison of methods for focusing the field of a HIFU array transducer through human ribs. Physics in Medicine and Biology, 59(12), 3139-3171. doi:10.1088/0031-9155/59/12/3139Fry, F. J., & Barger, J. E. (1978). Acoustical properties of the human skull. The Journal of the Acoustical Society of America, 63(5), 1576-1590. doi:10.1121/1.381852Thomas, J.-L., & Fink, M. A. (1996). Ultrasonic beam focusing through tissue inhomogeneities with a time reversal mirror: application to transskull therapy. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 43(6), 1122-1129. doi:10.1109/58.542055Hynynen, K., & Jolesz, F. A. (1998). Demonstration of Potential Noninvasive Ultrasound Brain Therapy Through an Intact Skull. Ultrasound in Medicine & Biology, 24(2), 275-283. doi:10.1016/s0301-5629(97)00269-xSun, J., & Hynynen, K. (1998). Focusing of therapeutic ultrasound through a human skull: A numerical study. The Journal of the Acoustical Society of America, 104(3), 1705-1715. doi:10.1121/1.424383Aubry, J.-F., Tanter, M., Pernot, M., Thomas, J.-L., & Fink, M. (2003). Experimental demonstration of noninvasive transskull adaptive focusing based on prior computed tomography scans. The Journal of the Acoustical Society of America, 113(1), 84-93. doi:10.1121/1.1529663Tanter, M., Thomas, J.-L., & Fink, M. (1998). Focusing and steering through absorbing and aberrating layers: Application to ultrasonic propagation through the skull. The Journal of the Acoustical Society of America, 103(5), 2403-2410. doi:10.1121/1.422759Hertzberg, Y., Volovick, A., Zur, Y., Medan, Y., Vitek, S., & Navon, G. (2010). Ultrasound focusing using magnetic resonance acoustic radiation force imaging: Application to ultrasound transcranial therapy. Medical Physics, 37(6Part1), 2934-2942. doi:10.1118/1.3395553Jolesz, F. A. (Ed.). (2014). Intraoperative Imaging and Image-Guided Therapy. doi:10.1007/978-1-4614-7657-3Shen, C., Xu, J., Fang, N. X., & Jing, Y. (2014). Anisotropic Complementary Acoustic Metamaterial for Canceling out Aberrating Layers. Physical Review X, 4(4). doi:10.1103/physrevx.4.041033Maimbourg, G., Houdouin, A., Deffieux, T., Tanter, M., & Aubry, J.-F. (2018). 3D-printed adaptive acoustic lens as a disruptive technology for transcranial ultrasound therapy using single-element transducers. Physics in Medicine & Biology, 63(2), 025026. doi:10.1088/1361-6560/aaa037Ferri, M., Bravo, J. M., Redondo, J., & Sánchez-Pérez, J. V. (2019). Enhanced Numerical Method for the Design of 3-D-Printed Holographic Acoustic Lenses for Aberration Correction of Single-Element Transcranial Focused Ultrasound. Ultrasound in Medicine & Biology, 45(3), 867-884. doi:10.1016/j.ultrasmedbio.2018.10.022Hynynen, K., McDannold, N., Vykhodtseva, N., & Jolesz, F. A. (2001). Noninvasive MR Imaging–guided Focal Opening of the Blood-Brain Barrier in Rabbits. Radiology, 220(3), 640-646. doi:10.1148/radiol.2202001804Tyler, W. J., Tufail, Y., Finsterwald, M., Tauchmann, M. L., Olson, E. J., & Majestic, C. (2008). Remote Excitation of Neuronal Circuits Using Low-Intensity, Low-Frequency Ultrasound. PLoS ONE, 3(10), e3511. doi:10.1371/journal.pone.0003511Schneider, U., Pedroni, E., & Lomax, A. (1996). The calibration of CT Hounsfield units for radiotherapy treatment planning. Physics in Medicine and Biology, 41(1), 111-124. doi:10.1088/0031-9155/41/1/009Mast, T. D. (2000). Empirical relationships between acoustic parameters in human soft tissues. Acoustics Research Letters Online, 1(2), 37-42. doi:10.1121/1.1336896Mazziotta, J. C., Toga, A. W., Evans, A., Fox, P., & Lancaster, J. (1995). A Probabilistic Atlas of the Human Brain: Theory and Rationale for Its Development. NeuroImage, 2(2), 89-101. doi:10.1006/nimg.1995.1012Yushkevich, P. A., Piven, J., Hazlett, H. C., Smith, R. G., Ho, S., Gee, J. C., & Gerig, G. (2006). User-guided 3D active contour segmentation of anatomical structures: Significantly improved efficiency and reliability. NeuroImage, 31(3), 1116-1128. doi:10.1016/j.neuroimage.2006.01.015Treeby, B. E., & Cox, B. T. (2010). Modeling power law absorption and dispersion for acoustic propagation using the fractional Laplacian. The Journal of the Acoustical Society of America, 127(5), 2741-2748. doi:10.1121/1.3377056Treeby, B. E., Jaros, J., Rendell, A. P., & Cox, B. T. (2012). Modeling nonlinear ultrasound propagation in heterogeneous media with power law absorption using a k-space pseudospectral method. The Journal of the Acoustical Society of America, 131(6), 4324-4336. doi:10.1121/1.4712021Jiménez, N., Camarena, F., Redondo, J., Sánchez-Morcillo, V., Hou, Y., & Konofagou, E. E. (2016). Time-Domain Simulation of Ultrasound Propagation in a Tissue-Like Medium Based on the Resolution of the Nonlinear Acoustic Constitutive Relations. Acta Acustica united with Acustica, 102(5), 876-892. doi:10.3813/aaa.919002Jiménez, N., Romero-García, V., Pagneux, V., & Groby, J.-P. (2017). Quasiperfect absorption by subwavelength acoustic panels in transmission using accumulation of resonances due to slow sound. Physical Review B, 95(1). doi:10.1103/physrevb.95.014205Tsang, P. W. M., & Poon, T.-C. (2013). Novel method for converting digital Fresnel hologram to phase-only hologram based on bidirectional error diffusion. Optics Express, 21(20), 23680. doi:10.1364/oe.21.023680Lirette, R., & Mobley, J. (2017). Focal zone characteristics of stepped Fresnel and axicon acoustic lenses. doi:10.1121/2.0000703Gatto, M., Memoli, G., Shaw, A., Sadhoo, N., Gelat, P., & Harris, R. A. (2012). Three-Dimensional Printing (3DP) of neonatal head phantom for ultrasound: Thermocouple embedding and simulation of bone. Medical Engineering & Physics, 34(7), 929-937. doi:10.1016/j.medengphy.2011.10.012Robertson, J., Martin, E., Cox, B., & Treeby, B. E. (2017). Sensitivity of simulated transcranial ultrasound fields to acoustic medium property maps. Physics in Medicine and Biology, 62(7), 2559-2580. doi:10.1088/1361-6560/aa5e98Hill, C. R., Bamber, J. C., & ter Haar, G. R. (Eds.). (2004). Physical Principles of Medical Ultrasonics. doi:10.1002/0470093978O’Neil, H. T. (1949). Theory of Focusing Radiators. The Journal of the Acoustical Society of America, 21(5), 516-526. doi:10.1121/1.1906542Chen, D.-C., Zhu, X.-F., Wei, Q., Wu, D.-J., & Liu, X.-J. (2018). Broadband acoustic focusing by Airy-like beams based on acoustic metasurfaces. Journal of Applied Physics, 123(4), 044503. doi:10.1063/1.501070

Equation level matching: An extension of the method of matched asymptotic expansion for problems of wave propagation

We introduce an alternative to the method of matched asymptotic expansions. In the "traditional" implementation, approximate solutions, valid in different (but overlapping) regions are matched by using "intermediate" variables. Here we propose to match at the level of the equations involved, via a "uniform expansion" whose equations enfold those of the approximations to be matched. This has the advantage that one does not need to explicitly solve the asymptotic equations to do the matching, which can be quite impossible for some problems. In addition, it allows matching to proceed in certain wave situations where the traditional approach fails because the time behaviors differ (e.g., one of the expansions does not include dissipation). On the other hand, this approach does not provide the fairly explicit approximations resulting from standard matching. In fact, this is not even its aim, which to produce the "simplest" set of equations that capture the behavior

An evidence-based approach to understanding the competency development needs of the health service management workforce in Australia

Background: Competent managers are essential to the productivity of organisations and the sustainability of health systems. Effective workforce development strategies sensitive to the current competency development needs of health service managers (HSMs) are required. Purpose: To conduct a 360° assessment of the competence of Australian HSMs to identify managerial competence levels, and training and development needs. Methods: Assessment of 93 middle-level HSMs from two public hospitals (n = 25) and five community health services (CHS) (n = 68), using the Managerial Competency Assessment Partnership (MCAP) framework and tool, conducted between 2012 and 2014 in Victoria, Australia. Results: Mean competency scores from both self- and combined colleagues' assessments indicated competence (scores greater than five but less than six) without guidance, but many HSMs have not had extensive experience. Around 12% of HSMs were unable to demonstrate the competency of 'evidence-informed decision-making' and 4% of HSMs were unable to demonstrate the competency of 'enabling and managing change'. Conclusion: The assessments confirmed managerial competence for the majority of middle-level HSMs from hospitals and CHS in Victoria, but found competency gaps. In addition, the assessment confirmed managerial strengths and weaknesses varied across management groups from different organisations. These findings suggest that the development of strategies to strengthen the health service management workforce should be multifaceted. Practice implications: A focus on competency in performance evaluation and development using the MCAP framework and tool not only provides insights into performance of HSMs, but also has the potential to provide an organisation strategic advantage through succession planning and advancing managers' competence via learning needs analysis and targeted professional development. Linking competencies of HSMs to organisational objectives and strategies provides optimal use of the human resource capacity, improving the organisation's productivity and sustainability

Face-to-face: Social work and evil

The concept of evil continues to feature in public discourses and has been reinvigorated in some academic disciplines and caring professions. This article navigates social workers through the controversy surrounding evil so that they are better equipped to acknowledge, reframe or repudiate attributions of evil in respect of themselves, their service users or the societal contexts impinging upon both. A tour of the landscape of evil brings us face-to-face with moral, administrative, societal and metaphysical evils, although it terminates in an exhortation to cultivate a more metaphorical language. The implications for social work ethics, practice and education are also discussed

The Use of Helmholtz Resonance for Measuring the Volume of Liquids and Solids

An experimental investigation was undertaken to ascertain the potential of using Helmholtz resonance for volume determination and the factors that may influence accuracy. The uses for a rapid non-interference volume measurement system range from agricultural produce and mineral sampling through to liquid fill measurements. By weighing the sample the density can also measured indirectly

Au-Ag template stripped pattern for scanning probe investigations of DNA arrays produced by Dip Pen Nanolithography

We report on DNA arrays produced by Dip Pen Nanolithography (DPN) on a novel Au-Ag micro patterned template stripped surface. DNA arrays have been investigated by atomic force microscopy (AFM) and scanning tunnelling microscopy (STM) showing that the patterned template stripped substrate enables easy retrieval of the DPN-functionalized zone with a standard optical microscope permitting a multi-instrument and multi-technique local detection and analysis. Moreover the smooth surface of the Au squares (abput 5-10 angstrom roughness) allows to be sensitive to the hybridization of the oligonucleotide array with label-free target DNA. Our Au-Ag substrates, combining the retrieving capabilities of the patterned surface with the smoothness of the template stripped technique, are candidates for the investigation of DPN nanostructures and for the development of label free detection methods for DNA nanoarrays based on the use of scanning probes.Comment: Langmuir (accepted

Adjuvant gemcitabine and concurrent radiation for patients with resected pancreatic cancer: a phase II study

The safety and efficacy of gemcitabine and concurrent radiation to the upper abdomen followed by weekly gemcitabine in patients with resected pancreatic cancer was determined. Patients with resected adenocarcinoma of the pancreas were treated with intravenous gemcitabine administered twice-weekly (40 mg m−2) for 5 weeks concurrent with upper abdominal radiation (50.4 Gy in 5½ weeks). At the completion of the chemoradiation, patients without disease progression were given gemcitabine (1000 mg m−2) weekly for two cycles. Each cycle consisted of 3 weeks of treatment followed by 1 week without treatment. Forty-seven patients were entered, 46 of whom are included in this analysis. Characteristics: median age 61 years (range 35–79); 24 females (58%); 73% stage T3/T4; and 70% lymph node positive. Grade III/IV gastrointestinal or haematologic toxicities were infrequent. The median survival was 18.3 months, while the median time to disease recurrence was 10.3 months. Twenty-four percent of patients were alive at 3 years. Only six of 34 patients with progression experienced local regional relapse as a component of the first site of failure. These results confirm the feasibility of delivering adjuvant concurrent gemcitabine and radiation to the upper abdomen. This strategy produced good local regional tumour control