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Flaum, Theodore B., Arfa Mirza, Frances Mary-Ann Rusnack, Theresa E. Apoznanski, Aida Munarova, Joseph Mazzie, Michael John Terzella et Sheldon C. Yao. « Palpatory and Ultrasound Assessment of Cervical Dysfunctions and the Effect of Cervical High-Velocity, Low-Amplitude (HVLA) Technique ». AAO Journal 27, no 3 (1 décembre 2017) : 9–16. http://dx.doi.org/10.53702/2375-5717-27.3.9.
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Abstract Background Ultrasound is commonly used to assess musculoskeletal abnormalities. High-velocity, low-amplitude (HVLA) is an osteopathic manipulative treatment technique commonly used by osteopathic physicians. The Shaw et al study has shown the reliability of ultrasound in measuring the improvement of rotational symmetry of lumbar somatic dysfunction (SD) after the use of HVLA. Objectives The purpose of this study was to evaluate the use of ultrasonography as a reference tool to quantitatively assess the rotational symmetry of cervical SD after the use of HVLA. Design The study was separated into 2 phases: 1) cervical diagnosis and pretreatment imaging and 2) HVLA or cranial vault hold (CVH) and post-treatment imaging. Method Two physicians independently diagnosed each participant (N = 51) with an SD between levels C2–C7; the key SD (the segment with the most posteriorly rotated articular pillar (AP)) was chosen. Ultrasound imaging was performed immediately after diagnosis. Next, the participants were randomly distributed into a treatment group, in which the participants were treated with HVLA, and a control group, in which a CVH was performed on the participant. Members of the HVLA group were then reassessed to confirm the key SD had resolved. Ultrasound imaging was immediately performed at the level of the segment with the key SD after HVLA reassessment or CVH completion. Results Physician reassessment confirmed SD resolution in 25 of 25 HVLA participants and 0 of 26 control participants. There was no significant change in ultrasound-measured AP rotation for the HVLA group (M=.05680 cm, P=.179) or control group (M=.02384 cm, P=.160). Conclusions Despite a palpatory resolution of the cervical SD, ultrasound was not able to determine a statistically significant change in AP rotation in either the HVLA or the control group.
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Hu, Annette, Thomas Motyka, Eric Gish et Godwin Dogbey. « Teaching and use of cervical high-velocity, low-amplitude manipulation at colleges of osteopathic medicine ». Journal of Osteopathic Medicine 121, no 3 (11 février 2021) : 265–70. http://dx.doi.org/10.1515/jom-2020-0120.
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Abstract Context Despite the documented effectiveness of high-velocity, low-amplitude (HVLA) treatment of the cervical spine, concerns about patient safety potentially limit didactic instruction and use in clinical practice. Understanding how cervical HVLA is taught and employed is of interest to osteopathic educators and clinicians. Objectives To characterize the perspectives of osteopathic manipulative medicine/osteopathic principles and practices (OMM/OPP) departments within colleges of osteopathic medicine (COMs) in the US regarding patterns of teaching and practice of HVLA treatment of the cervical spine. Methods A questionnaire was distributed on April 11, 2019 in paper format to OMM/OPP department chairs or designated faculty member attendees at the Educational Council on Osteopathic Principles biannual meeting. If the department chair was not available, the survey was provided to the faculty member designated to represent the Chair of the institution at ECOP. All respondents in this category returned the survey in paper before they left the meeting. The OMM/OPP department chairs who did not attend or send representatives to the ECOP meeting were sent the survey by email on April 11, 2019 and given three opportunities over 6 weeks at 2-week intervals to reply to this voluntary online survey. The survey was given or sent to a total of 51 OMM/OPP department chairs or representatives. Six questions elicited demographic information pertaining to status, age, gender, ethnicity, board-certified specialty, and COM affiliation. Nine questions examined perspectives related to the instruction of cervical HVLA manipulation and treatment. Results Of the 51 OMM/OPP department chairs surveyed, 38 (74.5%) responded, 32 to the paper survey at the ECOP meeting and six to the digital survey. Respondents were primarily dual Board-certified in Family Medicine and Neuromuscular Medicine (55.3%). At over 90% (35) of the COMs for which department chairs responded to the survey, cervical HVLA instruction occurs in the curriculum primarily during program years 1 and 2. Instruction in cervical HVLA to the 2nd through 7th cervical vertebral levels occurred in 97% (37), while 11% (4) of the COMs excluded the occipital-atlanto (OA) and atlanto-axial (AA) joints. A high percentage (81.6%; 31) of the OMM/OPP department chairs or representatives reported employing cervical HVLA techniques within their practice. Among the respondents, 40.5% (15) reported that 0–25% of their school’s medical school class could perform cervical HVLA competently upon graduation, whereas 27% (10) said that 51–75% of their class could perform cervical HVLA. Conclusions A majority of COMs provide education in their curricula related to cervical HVLA primarily in the first 2 years of medical education. However, instruction often excludes cervical HVLA to the upper regions of the cervical spine. At COMs where HVLA to the cervical spine is not taught, that decision is because the techniques are thought to be too difficult and the attendant medicolegal risk perceived to be too high. OMM/OPP department chairs expressed confidence in only a small proportion of their graduates having the ability to competently apply HVLA to the cervical spine immediately after completing their predoctoral medical training.
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Barnes, Precious L., Frank J. Casella, Hilda Lai, Olavi Airaksinen et Michael L. Kuchera. « Retention of tissue texture change after cervical muscle energy and high velocity low amplitude intervention : implications for treatment intervals ». Journal of Osteopathic Medicine 122, no 4 (24 janvier 2022) : 203–9. http://dx.doi.org/10.1515/jom-2021-0187.
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Abstract Context When choosing to incorporate osteopathic manipulative treatment (OMT) into a patient’s care, the risk-to-benefit ratio, the choice of treatment technique, as well as the frequency of treatments are always taken into consideration. This has been even more important during the COVID-19 pandemic, in which social distancing has been the best preventative measure to decrease exposure. By increasing treatment intervals, one could not only limit possible exposure/spread of viruses but also decrease the overall cost to the system as well as to the individual. This is an expansion of a previous study in which quantifiable changes in cervical hysteresis characteristics post-OMT were documented utilizing a durometer (Ultralign SA201®; Sigma Instruments; Cranberry, PA USA). This study compared two treatment modalities, muscle energy (ME) and high-velocity low-amplitude (HVLA) postcervical treatment. Subjects in this study were allowed to re-enroll, provided that they could be treated utilizing the alternate treatment modality. By allowing repeat subjects, analysis of the data for lasting effects of OMT could be observed. Objectives To determine whether a significant change in cervical hysteresis would be observed after each treatment regardless of a short treatment interval. Methods A total of 34 subjects were retrospectively noted to be repeat subjects from a larger, 213-subject study. These 34 subjects were repeat participants who were treated with two different direct-treatment modalities 7–10 days apart. Each subject was randomly assigned to receive a single-segmental ME or HVLA treatment technique directed toward a cervical (C) segment (C3–C5 only). Subjects were objectively measured pretreatment in all cervical segments utilizing the Ultralign SA201®, then treated with cervical OMT to a single segment, and finally reassessed at all cervical levels with the Ultralign SA201® posttreatment to assess for change in cervical hysteresis. Results Statistically significant or suggestive changes (p-values 0.01–0.08) with good clinical effect size (0.30 or greater) were noted in all four components of the Ultralign SA201® at multiple cervical levels after the first treatment, but only one component (frequency) had a statistically significant change after the second treatment (AA cervical level, p-value 0.01) with good clinical effect size (0.45). However, when comparing the post–first-treatment values to the pre–second-treatment values, no statistically significant differences (p-value 0.10 or higher) were observed between them. Conclusions Statistically significant changes were noted after the first treatment; however, when comparing cervical hysteresis changes after the first treatment to the cervical hysteresis values prior to the second treatment delivered 7–10 days later, there were no statistically significant or suggestive changes. This data suggest that several post-OMT changes noted after the first treatment were still in effect and may indicate that follow-up visits for direct manipulation may be deferred for a least two weeks.
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Price, James W. « A mixed treatment comparison of selected osteopathic techniques used to treat acute nonspecific low back pain : a proof of concept and plan for further research ». Journal of Osteopathic Medicine 121, no 6 (24 février 2021) : 571–82. http://dx.doi.org/10.1515/jom-2020-0268.
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Abstract Context Back injuries have a high prevalence in the United States and can be costly for both patients and the healthcare system at large. While previous guidelines from the American College of Physicians for the management of acute nonspecific low back pain (ANLBP) have encouraged nonpharmacologic management, those treatment recommendations involved only superficial heat, massage, acupuncture, and spinal manipulation. Investigation about the efficacy of spinal manipulation in the management of ANLBP is warranted. Objectives To compare the results in previously-published literature documenting the outcomes of osteopathic manipulative treatment (OMT) techniques used to treat ANLBP. The secondary objective of this study was to demonstrate the utility of using Bayesian network meta-analysis (NMA) to perform a mixed treatment comparison (MTC) of a variety of osteopathic techniques. Methods A literature search for randomized controlled trials (RCTs) of ANLBP treatments was performed in April 2020 according to PRISMA guidelines by searching MEDLINE/PubMed, OVID, Cochrane Central, PEDro, and OSTMED.Dr databases; scanning the reference lists of articles; and using the Canadian Agency for Drugs and Technologies in Health grey literature checklist. Each database was searched from inception to April 1, 2020. The following search terms were used: acute low back pain, acute low back pain plus physical therapy, acute low back pain plus spinal manipulation, and acute low back pain plus osteopathic manipulation. The validity of eligible trials was assessed by the single author using an adapted National Institute for Health and Care Excellence methodology checklist for randomized, controlled trials and an extraction form based on that checklist. The outcome measure chosen for this NMA was the Visual Analogue Scale of pain. The NMA were performed using the GeMTC user interface for automated NMA utilizing a Bayesian hierarchical model of random effects. Results The literature search initially found 483 unduplicated records. After screening and full text assessment, five RCTs were eligible for the MTC, yielding a total of 430 participants. Results of the MTC model suggested that there was no statistically significant decrease in reported pain when exercise, high-velocity low-amplitude (HVLA), counterstrain, muscle energy technique, or a mix of techniques were added to conventional treatment to treat ANLBP. However, the rank probabilities assessment determined that HVLA and the OMT mixed treatment protocol plus conventional care were ranked superior to conventional care alone for improving ANLBP. Conclusions While this study failed to provide definitive evidence upon which clinical recommendations can be based, it does demonstrate the utility of performing NMA for MTCs of osteopathic modalities used to treat ANLBP. However, to take full advantage of this statistical technique, future studies should be designed with consideration for the methodological shortcomings found in past osteopathic research.
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Shafqat, Sadaf. « EFFICACY OF HIGH-VELOCITY LOW-AMPLITUDE SPINAL MANIPULATION FOR NON SPECIFIC LOW BACK PAIN ». Pakistan Journal of Rehabilitation 3, no 1 (10 janvier 2014) : 4–14. http://dx.doi.org/10.36283/pjr.zu.3.1/009.
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BACKGROUND Back pain is one of the most frequently seen health problems, affecting 9 out of 10 people in a population at some point during their lives. The lower back is the region most commonly affected. Low-back pain can be debilitating, and it is often challenging to treat Low Back Pain. OBJECTIVE The objective of this review is to evaluate the efficacy of High-Velocity Low-Amplitude (HVLA) Spinal Manipulative Therapy (SMT) for Non Specific Low Back Pain (NSLBP). STUDY DESIGN Systemic review METHODS Only articles that had adult (18 years and above) participants were included in this review and studies that classified the intervention as HVLA spinal manipulation were included. Studies that included spinal manipulation other than HVLA or studies of spinal manipulation under anesthesia were excluded. RESULTS Eight full text papers and three systemic reviews justifying the inclusion criteria are reviewed which revealed that high velocity low amplitude spinal manipulative therapy have significant effect in alleviating low back pain. CONCLUSION Spinal manipulation therapy is a distinctive approach that considerably decreases nonspecific low back pain however there is need of further clinical trials into this subject focusing solely on high velocity low amplitude spinal manipulation.
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Haavik, Heidi, Imran Khan Niazi, Nitika Kumari, Imran Amjad, Jenna Duehr et Kelly Holt. « The Potential Mechanisms of High-Velocity, Low-Amplitude, Controlled Vertebral Thrusts on Neuroimmune Function : A Narrative Review ». Medicina 57, no 6 (27 mai 2021) : 536. http://dx.doi.org/10.3390/medicina57060536.
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The current COVID-19 pandemic has necessitated the need to find healthcare solutions that boost or support immunity. There is some evidence that high-velocity, low-amplitude (HVLA) controlled vertebral thrusts have the potential to modulate immune mediators. However, the mechanisms of the link between HVLA controlled vertebral thrusts and neuroimmune function and the associated potential clinical implications are less clear. This review aims to elucidate the underlying mechanisms that can explain the HVLA controlled vertebral thrust--neuroimmune link and discuss what this link implies for clinical practice and future research needs. A search for relevant articles published up until April 2021 was undertaken. Twenty-three published papers were found that explored the impact of HVLA controlled vertebral thrusts on neuroimmune markers, of which eighteen found a significant effect. These basic science studies show that HVLA controlled vertebral thrust influence the levels of immune mediators in the body, including neuropeptides, inflammatory markers, and endocrine markers. This narravtive review discusses the most likely mechanisms for how HVLA controlled vertebral thrusts could impact these immune markers. The mechanisms are most likely due to the known changes in proprioceptive processing that occur within the central nervous system (CNS), in particular within the prefrontal cortex, following HVLA spinal thrusts. The prefrontal cortex is involved in the regulation of the autonomic nervous system, the hypothalamic–pituitary–adrenal axis and the immune system. Bi-directional neuro-immune interactions are affected by emotional or pain-related stress. Stress-induced sympathetic nervous system activity also alters vertebral motor control. Therefore, there are biologically plausible direct and indirect mechanisms that link HVLA controlled vertebral thrusts to the immune system, suggesting HVLA controlled vertebral thrusts have the potential to modulate immune function. However, it is not yet known whether HVLA controlled vertebral thrusts have a clinically relevant impact on immunity. Further research is needed to explore the clinical impact of HVLA controlled vertebral thrusts on immune function.
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Karason, Agust B., et Ian P. Drysdale. « Somatovisceral response following osteopathic HVLAT : a pilot study on the effect of unilateral lumbosacral high-velocity low-amplitude thrust technique on the cutaneous blood flow in the lower limb ». Journal of Manipulative and Physiological Therapeutics 26, no 4 (mai 2003) : 220–25. http://dx.doi.org/10.1016/s0161-4754(02)54110-5.
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King, Alicia A., Jayme Cox, Shalini Bhatia et Karen T. Snider. « Characteristics and treatment of geriatric patients in an osteopathic neuromusculoskeletal medicine clinic ». Journal of Osteopathic Medicine 121, no 5 (19 février 2021) : 503–11. http://dx.doi.org/10.1515/jom-2020-0220.
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Abstract Context Osteopathic manipulative medicine (OMM) is an adjunctive treatment approach available to geriatric patients, but few studies provide details about presenting conditions, treatments, and response to osteopathic manipulative treatment (OMT) in that patient population. Objectives To provide descriptive data on the presentation and management of geriatric patients receiving OMT at an outpatient osteopathic neuromusculoskeletal medicine (ONMM) clinic. Methods Data were retrospectively collected from electronic health records (EHR) at a single outpatient clinic for clinical encounters with patients over 60 years of age who were treated with OMT between July 1, 2016, and June 30, 2019. Records were reviewed for demographic information, insurance type, presenting concerns, assessments, regions treated, OMT techniques used, and treatment response. Results There were 9,155 total clinical encounters with 1,238 unique patients found during the study period. More women than men were represented for overall encounters (6,910 [75.4%] vs. 2,254 [24.6%]) and unique patients (850 [68.7%] vs. 388 [31.3%]; both p<0.001). The mean (standard deviation, SD) number of encounters per patient per year was 4.5 (4.0) and increased with increasing age by decade (p<0.001). Medicare was the most common primary insurance (7,246 [79.2%]), with private insurance the most common secondary insurance (8,440 [92.2%]). The total number of presenting concerns was 12,020, and back concerns were most common (6,406 [53.3%]). The total number of assessments was 18,290; most were neuromusculoskeletal (17,271 [94.5%]) and in the thoracolumbar region (7,109 [38.9%]). The mean (SD) number of somatic dysfunction assessments per encounter was 5 (1.7); the thoracic region was the most documented and treated (7,263 [15.8%]). With up to 19 technique types per encounter, the total number of OMT techniques documented across all encounters was 43,862, and muscle energy (7,203 [16.4%]) was the most documented. The use of high-velocity, low-amplitude (HVLA) declined as age increased (p<0.001). The overall treatment response was documented in 7,316 (79.9%) encounters, and most indicated improvement (7,290 [99.6%]). Conclusions Our results showed that geriatric patients receiving OMT at our clinic were predominately presenting for neuromusculoskeletal concerns associated with back, neck, and extremity conditions, consistent with national epidemiological data for this population. The most common OMT techniques were also consistent with those used nationally by osteopathic medical students and practicing physicians. Future longitudinal studies are needed to determine the length of time improvement persists and the overall health impact experienced by geriatric patients receiving OMT.
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Shannon, Zacariah K., Robert D. Vining, Maruti Ram Gudavalli et Ron J. Boesch. « High-velocity, low-amplitude spinal manipulation training of prescribed forces and thrust duration : A pilot study ». Journal of Chiropractic Education 34, no 2 (5 avril 2019) : 107–15. http://dx.doi.org/10.7899/jce-18-19.
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Objective High-velocity, low-amplitude spinal manipulation (HVLA-SM) may generate different therapeutic effects depending on force and duration characteristics. Variability among clinicians suggests training to target specific thrust duration and force levels is necessary to standardize dosing. This pilot study assessed an HVLA-SM training program using prescribed force and thrust characteristics. Methods Over 4 weeks, chiropractors and students at a chiropractic college delivered thoracic region HVLA-SM to a prone mannequin in six training sessions, each 30 minutes in duration. Force plates embedded in a treatment table were used to measure force over time. Training goals were 350 and 550 Newtons (N) for peak force and ≤150 ms for thrust duration. Verbal and visual feedback was provided after each training thrust. Assessments included 10 consecutive thrusts for each force target without feedback. Mixed-model regression was used to analyze assessments measured before, immediately following, and 1, 4, and 8 weeks after training. Results Error from peak force target, expressed as adjusted mean constant error (standard deviation), went from 107 N (127) at baseline, to 0.2 N (41) immediately after training, and 32 N (53) 8 weeks after training for the 350 N target, and 63 N (148), −6 N (58), and 9 N (87) for the 550 N target. Student median values met thrust duration target, but doctors' were >150 ms immediately after training. Conclusion After participation in an HVLA-SM training program, participants more accurately delivered two prescribed peak forces, but accuracy decreased 1 week afterwards. Future HVLA-SM training research should include follow-up of 1 week or more to assess skill retention.
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Reed, William R., Dong-Yuan Cao, Cynthia R. Long, Gregory N. Kawchuk et Joel G. Pickar. « Relationship between Biomechanical Characteristics of Spinal Manipulation and Neural Responses in an Animal Model : Effect of Linear Control of Thrust Displacement versus Force, Thrust Amplitude, Thrust Duration, and Thrust Rate ». Evidence-Based Complementary and Alternative Medicine 2013 (2013) : 1–12. http://dx.doi.org/10.1155/2013/492039.
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High velocity low amplitude spinal manipulation (HVLA-SM) is used frequently to treat musculoskeletal complaints. Little is known about the intervention’s biomechanical characteristics that determine its clinical benefit. Using an animal preparation, we determined how neural activity from lumbar muscle spindles during a lumbar HVLA-SM is affected by the type of thrust control and by the thrust's amplitude, duration, and rate. A mechanical device was used to apply a linear increase in thrust displacement or force and to control thrust duration. Under displacement control, neural responses during the HVLA-SM increased in a fashion graded with thrust amplitude. Under force control neural responses were similar regardless of the thrust amplitude. Decreasing thrust durations at all thrust amplitudes except the smallest thrust displacement had an overall significant effect on increasing muscle spindle activity during the HVLA-SMs. Under force control, spindle responses specifically and significantly increased between thrust durations of 75 and 150 ms suggesting the presence of a threshold value. Thrust velocities greater than 20–30 mm/s and thrust rates greater than 300 N/s tended to maximize the spindle responses. This study provides a basis for considering biomechanical characteristics of an HVLA-SM that should be measured and reported in clinical efficacy studies to help define effective clinical dosages.
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Lima, Carla R., Daniel F. Martins, Snigdhasree Avatapally, Minjung Cho, Peng Li et William R. Reed. « Influence of Intervertebral Fixation and Segmental Thrust Level on Immediate Post-Spinal Manipulation Trunk Muscle Spindle Response in an Animal Model ». Brain Sciences 11, no 8 (31 juillet 2021) : 1022. http://dx.doi.org/10.3390/brainsci11081022.
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Objective: To characterize the effect of unilateral (single and two-level) lumbar facet/zygapophysial joint fixation on paraspinal muscle spindle activity immediately following L4 or L6 high velocity low amplitude spinal manipulation (HVLA-SM) delivered at various thrust durations. Methods: Secondary analysis of immediate (≤2 s) post-HVLA-SM trunk muscle spindle response from two studies involving anesthetized adult cats (n = 39; 2.3–6.0 kg) with either a unilateral single (L5/6) or two-level (L5/6 and L6/7) facet joint fixation. All facet fixations were contralateral to L6 dorsal root recordings. HVLA-SM was delivered to the spinous process in a posterior-to-anterior direction using a feedback motor with a peak thrust magnitude of 55% of average cat body weight and thrust durations of 75, 100, 150, and 250 ms. Time to 1st action potential and spindle activity during 1 and 2 s post-HVLA-SM comparisons were made between facet joint fixation conditions and HVLA-SM segmental thrust levels. Results: Neither two-level facet joint fixation, nor HVLA-SM segmental level significantly altered immediate post-HVLA-SM spindle discharge at tested thrust durations (FDR > 0.05). Conclusions: Two-level facet joint fixation failed to alter immediate (≤2 s) post-HVLA-SM spindle discharge when compared to single-level facet joint fixation at any thrust duration. Segmental thrust level did not alter immediate post-HVLA-SM spindle response in two-level facet joint fixation preparations.
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Coşkun, Reşat, Bülent Aksoy, Kerem Alptekin et Jülide Öncü Alptekin. « Efficiency of high velocity low amplitude (HVLA) lumbosacral manipulation on running time and jumping distance ». Manuelle Medizin 58, no 4-5 (4 mars 2020) : 229–36. http://dx.doi.org/10.1007/s00337-020-00663-9.
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Haavik, Heidi, Nitika Kumari, Kelly Holt, Imran Khan Niazi, Imran Amjad, Amit N. Pujari, Kemal Sitki Türker et Bernadette Murphy. « The contemporary model of vertebral column joint dysfunction and impact of high-velocity, low-amplitude controlled vertebral thrusts on neuromuscular function ». European Journal of Applied Physiology 121, no 10 (23 juin 2021) : 2675–720. http://dx.doi.org/10.1007/s00421-021-04727-z.
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Abstract Purpose There is growing evidence that vertebral column function and dysfunction play a vital role in neuromuscular control. This invited review summarises the evidence about how vertebral column dysfunction, known as a central segmental motor control (CSMC) problem, alters neuromuscular function and how spinal adjustments (high-velocity, low-amplitude or HVLA thrusts directed at a CSMC problem) and spinal manipulation (HVLA thrusts directed at segments of the vertebral column that may not have clinical indicators of a CSMC problem) alters neuromuscular function. Methods The current review elucidates the peripheral mechanisms by which CSMC problems, the spinal adjustment or spinal manipulation alter the afferent input from the paravertebral tissues. It summarises the contemporary model that provides a biologically plausible explanation for CSMC problems, the manipulable spinal lesion. This review also summarises the contemporary, biologically plausible understanding about how spinal adjustments enable more efficient production of muscular force. The evidence showing how spinal dysfunction, spinal manipulation and spinal adjustments alter central multimodal integration and motor control centres will be covered in a second invited review. Results Many studies have shown spinal adjustments increase voluntary force and prevent fatigue, which mainly occurs due to altered supraspinal excitability and multimodal integration. The literature suggests physical injury, pain, inflammation, and acute or chronic physiological or psychological stress can alter the vertebral column’s central neural motor control, leading to a CSMC problem. The many gaps in the literature have been identified, along with suggestions for future studies. Conclusion Spinal adjustments of CSMC problems impact motor control in a variety of ways. These include increasing muscle force and preventing fatigue. These changes in neuromuscular function most likely occur due to changes in supraspinal excitability. The current contemporary model of the CSMC problem, and our understanding of the mechanisms of spinal adjustments, provide a biologically plausible explanation for how the vertebral column’s central neural motor control can dysfunction, can lead to a self-perpetuating central segmental motor control problem, and how HVLA spinal adjustments can improve neuromuscular function.
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Gómez, Francisco, Pablo Escribá, Jesús Oliva-Pascual-Vaca, Roberto Méndez-Sánchez et Ana Silvia Puente-González. « Immediate and Short-Term Effects of Upper Cervical High-Velocity, Low-Amplitude Manipulation on Standing Postural Control and Cervical Mobility in Chronic Nonspecific Neck Pain : A Randomized Controlled Trial ». Journal of Clinical Medicine 9, no 8 (10 août 2020) : 2580. http://dx.doi.org/10.3390/jcm9082580.
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This study aimed to determine the immediate and short-term effects of a single upper cervical high-velocity, low-amplitude (HVLA) manipulation on standing postural control and cervical mobility in chronic nonspecific neck pain (CNSNP). A double-blinded, randomized placebo-controlled trial was performed. Forty-four patients with CNSNP were allocated to the experimental group (n = 22) or control group (n = 22). All participants were assessed before and immediately after the intervention, with a follow-up on the 7th and 15th days. In each evaluation, we assessed global and specific stabilometric parameters to analyze standing postural balance and performed the cervical flexion-rotation test (CFRT) to analyze upper cervical mobility. We obtained statistically significant differences, with a large effect size, in the limited cervical rotation and global stabilometric parameters. Upper cervical HVLA manipulation produced an improvement in the global stabilometric parameters, significantly decreasing the mean values of velocity, surface, path length, and pressure in all assessments (p < 0.001; ƞ 2 p = 0.323–0.856), as well as significantly decreasing the surface length ratio (L/S) on the 7th (−0.219 1/mm; p = 0.008; 95% confidence interval (CI): 0.042–0.395) and 15th days (−0.447 1/mm; p < 0.001; 95% CI: 0.265–0.629). Limited cervical rotation values increased significantly immediately after manipulation (7.409°; p < 0.001; 95% CI: 6.131–8.687) and were maintained during follow-up (p < 0.001). These results show that a single upper cervical HVLA manipulation produces an improvement in standing postural control and increases the rotational range of motion (ROM) in the upper cervical spine in patients with CNSNP.
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Shin, Ho-Jin, Sung-Hyeon Kim, Han Jo Jung, Hwi-young Cho et Suk-Chan Hahm. « Manipulative Therapy Plus Ankle Therapeutic Exercises for Adolescent Baseball Players with Chronic Ankle Instability : A Single-Blinded Randomized Controlled Trial ». International Journal of Environmental Research and Public Health 17, no 14 (11 juillet 2020) : 4997. http://dx.doi.org/10.3390/ijerph17144997.
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Manipulative therapies and exercises are commonly used for the management of chronic ankle instability (CAI), but there is no evidence regarding the efficacy of high-velocity low-amplitude manipulation (HVLA) in addition to ankle therapeutic exercise to improve CAI in adolescent baseball players (ABP). To compare the effects of HVLA plus ankle therapeutic exercise and ankle therapeutic exercise alone on ankle status, pain intensity, pain pressure threshold (PPT), range of motion (ROM) of the ankle joint, and balance ability in ABP with CAI, a single-blinded randomized controlled trial was conducted. A total of 31 ABP with CAI were randomly allocated to the intervention (n = 16) or control (n = 15) groups. The intervention group received HVLA plus resistance exercise twice a week for 4 weeks, while the control group received resistance exercise alone. Ankle status, pain intensity, PPT, ROM, and balance ability were assessed before and after the intervention. The American Orthopedic Foot and Ankle Society scores showed significant group and time interactions (total, p = 0.002; pain, p < 0.001; alignment, p = 0.001). There were significant group and time interactions in pain intensity (resting pain, p = 0.008; movement pain, p < 0.001). For ROM, there were significant group and time interactions on dorsiflexion (p = 0.006) and eversion (p = 0.026). The unipedal stance of the balance ability showed significant group and time interactions in path length (p = 0.006) and velocity (p = 0.006). Adding HVLA to resistance exercises may be synergistically effective in improving the ankle status, pain intensity, ROM, and balance ability in ABP with CAI.
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Meeker, William C., Cynthia R. Long, Maria A. Hondras, Edward F. Owens, M. Ram Gudavalli, James W. DeVocht, David G. Wilder, Robert M. Rowell et Christine M. Goertz. « Patient characteristics associated with improvement of subacute and chronic low back pain treated with high velocity low amplitude (HVLA) or low velocity variable amplitude (LVVA) spinal manipulation ». Clinical Chiropractic 14, no 4 (décembre 2011) : 145. http://dx.doi.org/10.1016/j.clch.2011.09.004.
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Demoulin, C., D. Baeri, G. Toussaint, M. Tomasella, Y. Depas, S. Grosdent, A. Beernaert, B. Cagnie, J. M. Crielaard et M. Vanderthommen. « Do beliefs and knowledge about Spinal High-Velocity Low-Amplitude (HVLA) manipulations differ between individuals with or without a history of spinal HVLA manipulation(s) ? » Manual Therapy 25 (septembre 2016) : e109. http://dx.doi.org/10.1016/j.math.2016.05.194.
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Vasave, Dr Tejaswini, et Dr Sanket Nagrale. « Effect of lumbar high velocity low amplitude (HVLA) thrust on speed and agility in elite athletes : A randomised controlled trial ». International Journal of Applied Research 8, no 2 (1 février 2022) : 492–502. http://dx.doi.org/10.22271/allresearch.2022.v8.i2g.9487.
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de Toledo, Danielle de Faria Alvim, Frederico Barreto Kochem et Julio Guilherme Silva. « High-velocity, low-amplitude manipulation (HVLA) does not alter three-dimensional position of sacroiliac joint in healthy men : A quasi-experimental study ». Journal of Bodywork and Movement Therapies 24, no 1 (janvier 2020) : 190–93. http://dx.doi.org/10.1016/j.jbmt.2019.05.020.
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Punia, Sonu, Manoj Malik, Shalu Jangra, Jaspreet Kaur et Varun Singh. « Effect of High-Velocity Low-Amplitude Thrust Manipulation of Upper Cervical Spine on Pulmonary Function Test and Headache Disability Index in Patients with Migraine Headache ». Polish Journal of Sport and Tourism 27, no 4 (1 décembre 2020) : 18–22. http://dx.doi.org/10.2478/pjst-2020-0022.
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Abstract Introduction. Migraine is a common debilitating disorder of neurovascular origin which affects younger adults, especially women. Material and Methods. It was an experimental study design. A convenience type of sampling was used for recruitment of the subjects. A total of 21 participants diagnosed with migraine (6 males and 15 females) fulfilling the inclusion criteria were taken for this study and assigned to one of the two groups (experimental or control group). PFT measured with PFT apparatus (Spirolab 111, Serial No. A23-053 13974) and HDI score were calculated before the start of the intervention and after the intervention. Afterwards, PFT was performed by each participant followed by HVLA thrust manipulations to the migraine patients and an equal period of rest to the control group. Results. There are no significant differences between baseline and post-intervention outcome variables and in mean changes between the two groups. One-way ANOVA was used to analyze the change in HDI score which was calculated three times (pre- prior to intervention, post- after the intervention and 1 month after the intervention). The experimental group showed a significant reduction in the score after the manipulation. It was found that FVC and PEF were positively correlated to FEV1, and FVC was also positively correlated to PEF. Conclusions. The findings of the study revealed that high-velocity thrust manipulations of upper cervical spine were not effective in improving pulmonary functions of migraine patients although it was found effective in improving subjective symptoms of the patients evaluated through HDI.
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Higgins, Brian E., et David A. Patriquin. « A low-velocity, high-amplitude procedure for demonstrating osteopathic principles and concepts of technique ». Journal of the American Osteopathic Association 87, no 1 (1 janvier 1987) : 127–34. http://dx.doi.org/10.1515/jom-1987-870124.
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Boesler, David, Michael Warner, Adam Alpers, Edward Patrick Finnerty et Mearl A. Kilmore. « Efficacy of high-velocity low-amplitude manipulative technique in subjects with low-back pain during menstrual cramping ». Journal of the American Osteopathic Association 93, no 2 (1 février 1993) : 203. http://dx.doi.org/10.7556/jaoa.1993.93.2.203.
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Hennenhoefer, Kevin, et Deborah Schmidt. « Toward a Theory of the Mechanism of High-Velocity, Low-Amplitude Technique : A Literature Review ». Journal of the American Osteopathic Association 119, no 10 (1 octobre 2019) : 688. http://dx.doi.org/10.7556/jaoa.2019.116.
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Hamilton, Luke, Caitlin Boswell et Gary Fryer. « The effects of high-velocity, low-amplitude manipulation and muscle energy technique on suboccipital tenderness ». International Journal of Osteopathic Medicine 10, no 2-3 (juin 2007) : 42–49. http://dx.doi.org/10.1016/j.ijosm.2007.08.002.
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Lopes, Mark A., Roger R. Coleman et Edward J. Cremata. « Radiography and Clinical Decision-Making in Chiropractic ». Dose-Response 19, no 4 (octobre 2021) : 155932582110448. http://dx.doi.org/10.1177/15593258211044844.
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The concern over x-ray exposure risks can overshadow the potential benefit of radiography, especially in cases where manual therapy is employed. Spinal malalignment cannot be accurately visualized without imaging. Manual therapy and the load tolerances of injured spinal tissues raise different criteria for the use of x-rays for spinal disorders than in medical practice. Current regulatory bodies rely on radiography risk assessments based on Linear-No-Threshold (LNT) risk models. There is a need to consider radiography guidelines for chiropractic which are different from those for medical practice. Radiography practice guidelines are summaries dominated by frequentist interpretations in the analysis of data from studies. In contrast, clinicians often employ a pseudo-Bayesian form of reasoning during the clinical decision-making process. The overrepresentation of frequentist perspectives in evidence-based practice guidelines alter decision-making away from practical assessment of a patient’s needs, toward an overly cautious standard applied to patients without regard to their risk/benefit likelihoods relating to radiography. Guidelines for radiography in chiropractic to fully assess the condition of the spine and spinal alignment prior to manual therapy, especially with high velocity, low amplitude spinal manipulation (HVLA-SM), should necessarily differ from those used in medical practice.
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Lopes, Mark A., Roger R. Coleman et Edward J. Cremata. « Radiography and Clinical Decision-Making in Chiropractic ». Dose-Response 19, no 4 (octobre 2021) : 155932582110448. http://dx.doi.org/10.1177/15593258211044844.
Texte intégralRésumé :
The concern over x-ray exposure risks can overshadow the potential benefit of radiography, especially in cases where manual therapy is employed. Spinal malalignment cannot be accurately visualized without imaging. Manual therapy and the load tolerances of injured spinal tissues raise different criteria for the use of x-rays for spinal disorders than in medical practice. Current regulatory bodies rely on radiography risk assessments based on Linear-No-Threshold (LNT) risk models. There is a need to consider radiography guidelines for chiropractic which are different from those for medical practice. Radiography practice guidelines are summaries dominated by frequentist interpretations in the analysis of data from studies. In contrast, clinicians often employ a pseudo-Bayesian form of reasoning during the clinical decision-making process. The overrepresentation of frequentist perspectives in evidence-based practice guidelines alter decision-making away from practical assessment of a patient’s needs, toward an overly cautious standard applied to patients without regard to their risk/benefit likelihoods relating to radiography. Guidelines for radiography in chiropractic to fully assess the condition of the spine and spinal alignment prior to manual therapy, especially with high velocity, low amplitude spinal manipulation (HVLA-SM), should necessarily differ from those used in medical practice.
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Owens, Edward F., Ronald S. Hosek, Stephanie G. B. Sullivan, Brent S. Russell, Linda E. Mullin et Lydia L. Dever. « Establishing force and speed training targets for lumbar spine high-velocity, low-amplitude chiropractic adjustments* ». Journal of Chiropractic Education 30, no 1 (1 mars 2016) : 7–13. http://dx.doi.org/10.7899/jce-15-5.
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Objective: We developed an adjusting bench with a force plate supporting the lumbar portion to measure loads transmitted during lumbar manual adjustment. It will be used to provide force-feedback to enhance student learning in technique labs. The study goal is to define the learning target loads and speeds, with instructors as expert models. Methods: A total of 11 faculty members experienced in teaching Gonstead technique methods performed 81 simulated adjustments on a mannequin on the force plate. Adjustments were along 9 lumbopelvic “listings” at 3 load levels: light, normal, and heavy. We analyzed the thrusts to find preload, peak load, duration, and thrust rate. Results: Analysis of 891 thrusts showed wide variations between doctors. Peak loads ranged from 100 to 1400 N. All doctors showed clear distinctions between peak load levels, but there was overlap between high and low loads. Thrust rates were more uniform across doctors, averaging 3 N/ms. Conclusion: These faculty members delivered a range of thrusts, not unlike those seen in the literature for high velocity, low amplitude manipulation. We have established at least minimum force and speed targets for student performance, but more work must be done to create a normative adjustment to guide refinement of student learning.
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Chen, Hao, Xiao Yan Tong, Xiang Zheng et Lei Jiang Yao. « Acoustic Emission Analysis of Composite Laminates under Low Velocity Impact ». Advanced Materials Research 118-120 (juin 2010) : 216–20. http://dx.doi.org/10.4028/www.scientific.net/amr.118-120.216.
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One of the problems preventing the industrial application of composites is the lack of an efficient method to detect and discriminate among types of damage occurring during service. To solve this problem, low velocity impact experiments are carried out on T300/QY8911 composite laminates. And synchronously, the acoustic emission (AE) technique and impact monitoring systems were used to record the AE signals and the impact force. The damage evolution, damage modes and acoustic emission (AE) activity were easily detected and evaluated by the analysis of both AE waveform and impact load. In this way, the damage development process containing matrix cracking, delamination and fibers breakage is investigated. The energy release of damage are theoretically approximated and correlated with the AE energy. By the theory, the “high energy damage zone” is defined in the scatter diagrams of amplitude-frequency. It is easily to prove that the primary damage mode of “high energy damage zone” is delamination.
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Fatti, Jan L., George C. Smith, Peter J. Vail, Peter J. Strauss et Philip R. Levitt. « Detection of gas in sandstone reservoirs using AVO analysis : A 3-D seismic case history using the Geostack technique ». GEOPHYSICS 59, no 9 (septembre 1994) : 1362–76. http://dx.doi.org/10.1190/1.1443695.
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The Geostack technique is a method of analyzing seismic amplitude variation with offset (AVO) information. One of the outputs of the analysis is a set of direct hydrocarbon indicator traces called “fluid factor” traces. The fluid factor trace is designed to be low amplitude for all reflectors in a clastic sedimentary sequence except for rocks that lie off the (mudrock line.) The mudrock line is the line on a crossplot of P‐wave velocity against S‐wave velocity on which water‐saturated sandstones, shales, and siltstones lie. Some of the rock types that lie off the mudrock line are gas‐saturated sandstones, carbonates, and igneous rocks. In the absence of carbonates and igneous rocks, high amplitude reflections on fluid factor traces would be expected to represent gas‐saturated sandstones. Of course, this relationship does not apply exactly in nature, and the extent to which the mudrock line model applies varies from area to area. However, it is a useful model in many basins of the world, including the one studied here. Geostack processing has been done on a 3-D seismic data set over the Mossel Bay gas field on the southern continental shelf of South Africa. We found that anomalously high amplitude fluid factor reflections occurred at the top and base of the gas‐reservoir sandstone. Maps were made of the amplitude of these fluid factor reflections, and it was found that the high amplitude values were restricted mainly to the gas field area as determined by drilling. The highest amplitudes were found to be located roughly in the areas of best reservoir quality (i.e., highest porosity) in areas where the reservoir is relatively thick.
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Singh, Varun, et Manoj Malik. « Efficacy of manual therapy interventions in management of lumbar prolapsed intervertebral disc : A pilot randomized controlled trial ». Romanian Journal of Neurology 20, no 3 (30 septembre 2021) : 373–78. http://dx.doi.org/10.37897/rjn.2021.3.18.
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Background. This pilot trial reports the initial estimates of the efficacy of manual therapy interventions in lumbar prolapsed intervertebral disc and determines the feasibility and acceptability of full powered “randomized controlled trial” on efficacy of “spinal mobilization with leg movement (SMWLM)”, high velocity low amplitude thrust (HVLA) and neural mobilization (NM) in lumbar PIVD (Prolapsed Inter-Vertebral Disc) and pilot data will be used to perform sample size calculation for full trial. Material and methods. 48 subjects diagnosed lumbar PIVD were randomly distributed into 4 groups. The primary outcomes were feasibility, assessment procedure, retention rate, adherence and acceptability to the intervention. The secondary outcomes measures were pain, disability and straight leg raise (SLR) range of motion. Results. 90 subjects were screened based on selection criteria. Out of them, 50 (55.55%) were eligible. 48(96%) subjects accepted to participate in study. Baseline data of all the groups was similar but post-intervention score were significant when compared the data between the groups. Highest mean change for visual analog scale (VAS), oswestry disability index (ODI) and SLR were found in SMWLM group. No adverse effects were reported by subjects. Results also suggest that the outcome measures were feasible and acceptable and the treatment considered as the beneficial approach. Conclusions. Present study suggests that it is feasible and acceptable to do a fully powered “randomized controlled trial (RCT)” to evaluate the efficacy of manual therapy interventions in management of lumbar PIVD. This study also reveals that manual therapy interventions are effective in management of lumbar PIVD.
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BENABDALLAH, Hadjer, et Salim Kerai. « The impedance cardiography technique in medical diagnosis ». Medical Technologies Journal 2, no 3 (30 septembre 2018) : 232–44. http://dx.doi.org/10.26415/2572-004x-vol2iss3p232-244.
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Background: Thoracic Electrical Bioimpedance (TEB) Technology sometimes called the Impedance Cardiography (ICG). In 1940, the Impedance Cardiography emerged; the studies of this technique are realized to the cardiovascular diseases detection which used hemodynamic parameters measurements based on the skin electrodes contact by injecting a low amplitude alternating signal. The objective of this article is to review the various studies based on this signal type and to present the multiple methods used for the treatment and to have a correct analysis.
Methods: This ICG technique consists for applying an electric field longitudinally across a segment of the thorax with amplitude in mean, high frequency and low amplitude current. To analyze the ICG signal, the signal denoising is necessary that’s why a multiple filters are proposed, and the Discrete Wavelet Transform (DWT) denoising is also used.
Results: The ICG is considered advantageous compared to other invasive conventional techniques; it gives a good correlation, and solves the Doppler ultrasound and Thermodilution problems. According to the studies, the Daubechies wavelet family (db8) is the best DWT to eliminate the noises. There are several algorithms for the signal characteristic point’s detection.
Conclusion: For the purpose of cardiovascular disease diagnosis and monitoring, the non-invasive ICG technique comes to solve the complexity problem for measurement and analyzing heart disease based on the thoracic electrical impedance change assessment that is due to blood velocity and resistivity changes (blood volume changes) in order to estimate several hemodynamic parameters.
Keywords: ICG, cardiovascular disease, hemodynamic parameters, diagnosis and monitoring, correct analysis.
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Yang, Mengmeng, Marie Graff, Rajiv Kumar et Felix J. Herrmann. « Low-rank representation of omnidirectional subsurface extended image volumes ». GEOPHYSICS 86, no 3 (11 mars 2021) : S165—S183. http://dx.doi.org/10.1190/geo2020-0152.1.
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Subsurface-offset gathers play an increasingly important role in seismic imaging. These gathers are used during velocity model building and inversion of rock properties from amplitude variations. Although powerful, these gathers come with high computational and storage demands to form and manipulate these high-dimensional objects. This explains why only limited numbers of image gathers are computed over a limited offset range. We avoid these high costs by working with highly compressed low-rank factorizations. These factorizations are obtained via a combination of probings with the double two-way wave equation and randomized singular-value decompositions. In turn, the resulting factorizations give us access to all subsurface offsets without having to form the full extended image volumes (EIVs) that are at best quadratic in image size. As a result, we can easily handle situations in which conventional horizontal offset gathers are no longer focused. More importantly, the factorization also provides a mechanism to use the invariance relation of EIVs for velocity continuation. With this technique, EIVs for one background velocity model can be directly mapped to those of another background velocity model. Our low-rank factorization inherits this invariance property, so that factorization costs arise only once when examining different imaging scenarios. Because all imaging experiments only involve the factors, they are computationally efficient with costs that scale with the rank of the factorization. Examples using 2D synthetics, including a challenging imaging example with salt, validate the methodology. Instead of brute-force explicit crosscorrelations between shifted source and receiver wavefields, our approach relies on the underlying linear-algebra structure that enables us to work with these objects without incurring unfeasible demands on computation and storage.
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Timmann, D., S. Watts et J. Hore. « Failure of Cerebellar Patients to Time Finger Opening Precisely Causes Ball High-Low Inaccuracy in Overarm Throws ». Journal of Neurophysiology 82, no 1 (1 juillet 1999) : 103–14. http://dx.doi.org/10.1152/jn.1999.82.1.103.
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We investigated the idea that the cerebellum is required for precise timing of fast skilled arm movements by studying one situation where timing precision is required, namely finger opening in overarm throwing. Specifically, we tested the hypothesis that in overarm throws made by cerebellar patients, ball high-low inaccuracy is due to disordered timing of finger opening. Six cerebellar patients and six matched control subjects were instructed to throw tennis balls at three different speeds from a seated position while angular positions in three dimensions of five arm segments were recorded at 1,000 Hz with the search-coil technique. Cerebellar patients threw more slowly than controls, were markedly less accurate, had more variable hand trajectories, and showed increased variability in the timing, amplitude, and velocity of finger opening. Ball high-low inaccuracy was not related to variability in the height or direction of the hand trajectory or to variability in finger amplitude or velocity. Instead, the cause was variable timing of finger opening and thereby ball release occurring on a flattened arc hand trajectory. The ranges of finger opening times and ball release times (timing windows) for 95% of the throws were on average four to five times longer for cerebellar patients; e.g., across subjects mean ball release timing windows for throws made under the medium-speed instruction were 11 ms for controls and 55 ms for cerebellar patients. This increased timing variability could not be explained by disorder in control of force at the fingers. Because finger opening in throwing is likely controlled by a central command, the results implicate the cerebellum in timing the central command that initiates finger opening in this fast skilled multijoint arm movement.
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Zhang, Haotian, Linjian Ma, Zongmu Luo et Ning Zhang. « Wave Attenuation and Dispersion in a 6 mm Diameter Viscoelastic Split Hopkinson Pressure Bar and Its Correction Method ». Shock and Vibration 2020 (16 novembre 2020) : 1–10. http://dx.doi.org/10.1155/2020/8888445.
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The propagation characteristics of viscoelastic waves have been investigated with a 6 mm diameter split Hopkinson pressure bar (SHPB) made of polymethyl methacrylate (PMMA). The strain signals in SHPB tests were improved by the pulse shaping technique. Based on the experimentally determined propagation coefficients, the amplitude attenuation and wave dispersion induced by viscoelastic effects at different impact velocities were quantitatively analyzed. The results indicate that the high-frequency harmonics attenuate faster in a higher phase velocity. With an increase in the impact velocity, the amplitude attenuation of the viscoelastic wave changes slightly during propagation, while the waveform dispersion gradually intensifies. A feasible method by waveform prediction was proposed to verify the validity and applicability of the propagation coefficient. The results indicate that the strain obtained from the small diameter viscoelastic SHPB can be effectively modified by utilizing the propagation coefficient. Furthermore, it is preferred to adopt the propagation coefficient obtained at low impact velocity for correction when the impact velocity varies. Moreover, the PMMA-steel bar impact test was performed to further illustrate the accuracy of the propagation coefficient and the effectiveness of the correction method.
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Smith, Lucie, et Manoj Mehta. « The effects of upper cervical complex high velocity low amplitude thrust technique and sub-occipital muscle group inhibition techniques on standing balance ». International Journal of Osteopathic Medicine 11, no 4 (décembre 2008) : 162. http://dx.doi.org/10.1016/j.ijosm.2008.08.020.
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Wang, Yibo, Yikang Zheng, Qingfeng Xue, Xu Chang, Tong W. Fei et Yi Luo. « Reverse time migration of multiples : Reducing migration artifacts using the wavefield decomposition imaging condition ». GEOPHYSICS 82, no 4 (1 juillet 2017) : S307—S314. http://dx.doi.org/10.1190/geo2016-0354.1.
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In the implementation of migration of multiples, reverse time migration (RTM) is superior to other migration algorithms because it can handle steeply dipping structures and offer high-resolution images of the complex subsurface. However, the RTM results using two-way wave equation contain high-amplitude, low-frequency noise and false images generated by improper wave paths in migration velocity model with sharp velocity interfaces or strong velocity gradients. To improve the imaging quality in RTM of multiples, we separate the upgoing and downgoing waves in the propagation of source and receiver wavefields. A complex function involved with the Hilbert transform is used in wavefield decomposition. Our approach is cost effective and avoids the large storage of wavefield snapshots required by the conventional wavefield separation technique. We applied migration of multiples with wavefield decomposition on a simple two-layer model and the Sigsbee 2B synthetic data set. Our results demonstrate that the proposed approach can improve the image generated by migration of multiples significantly.
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Wang, Chao, Shabnam Z. Bonyadi, Florian Grün, Gerald Pinter, Andreas Hausberger et Alison C. Dunn. « Precise Correlation of Contact Area and Forces in the Unstable Friction between a Rough Fluoroelastomer Surface and Borosilicate Glass ». Materials 13, no 20 (16 octobre 2020) : 4615. http://dx.doi.org/10.3390/ma13204615.
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Stick-slip friction of elastomers arises due to adhesion, high local strains, surface features, and viscous dissipation. In situ techniques connecting the real contact area to interfacial forces can reveal the contact evolution of a rough elastomer surface leading up to gross slip, as well as provide high-resolution dynamic contact areas for improving current slip models. Samples with rough surfaces were produced by the same manufacturing processes as machined seals. In this work, a machined fluoroelastomer (FKM) hemisphere was slid against glass, and the stick-slip behavior was captured optically in situ. The influence of sliding velocity on sliding behavior was studied over a range of speeds from 1 µm/s to 100 µm/s. The real contact area was measured from image sequences thresholded using Otsu’s method. The motion of the pinned region was delineated with a machine learning scheme. The first result is that, within the macroscale sticking, or pinned phase, local pinned and partial slip regions were observed and modeled as a combined contact with contributions to friction by both regions. As a second result, we identified a critical velocity below which the stick-slip motion converted from high frequency with low amplitude to low frequency with high amplitude. This study on the sliding behavior of a viscoelastic machined elastomer demonstrates a multi-technique approach which reveals precise changes in contact area before and during pinning and slip.
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Ramos, Antonio C. B., et John P. Castagna. « Useful approximations for converted‐wave AVO ». GEOPHYSICS 66, no 6 (novembre 2001) : 1721–34. http://dx.doi.org/10.1190/1.1487114.
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Converted‐wave amplitude versus offset (AVO) behavior may be fit with a cubic relationship between reflection coefficient and ray parameter. Attributes extracted using this form can be directly related to elastic parameters with low‐contrast or high‐contrast approximations to the Zoeppritz equations. The high‐contrast approximation has the advantage of greater accuracy; the low‐contrast approximation is analytically simpler. The two coefficients of the low‐contrast approximation are a function of the average ratio of compressional‐to‐shear‐wave velocity (α/β) and the fractional changes in S‐wave velocity and density (Δβ/β and Δρ/ρ). Because of its simplicity, the low‐contrast approximation is subject to errors, particularly for large positive contrasts in P‐wave velocity associated with negative contrasts in S‐wave velocity. However, for incidence angles up to 40° and models confined to |Δβ/β| < 0.25, the errors in both coefficients are relatively small. Converted‐wave AVO crossplotting of the coefficients of the low‐contrast approximation is a useful interpretation technique. The background trend in this case has a negative slope and an intercept proportional to the α/β ratio and the fractional change in S‐wave velocity. For constant α/β ratio, an attribute trace formed by the weighted sum of the coefficients of the low‐contrast approximation provides useful estimates of the fractional change in S‐wave velocity and density. Using synthetic examples, we investigate the sensitivity of these parameters to random noise. Integrated P‐wave and converted‐wave analysis may improve estimation of rock properties by combining extracted attributes to yield fractional contrasts in P‐wave and S‐wave velocities and density. Together, these parameters may provide improved direct hydrocarbon indication and can potentially be used to identify anomalies caused by low gas saturations.
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Chun, Kin-Yip, Richard J. Kokoski et Gordon F. West. « High-frequency Pn attenuation in the Canadian shield ». Bulletin of the Seismological Society of America 79, no 4 (1 août 1989) : 1039–53. http://dx.doi.org/10.1785/bssa0790041039.
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Abstract Frequency-dependent spatial attenuation of Pn waves, incorporating the combined effects of geometrical spreading and anelastic dissipation, is investigated in eastern Canada between 3 and 15 Hz. Measurement of this total attenuation, instead of the two separate effects, circumvents the usual need for making a priori assumptions regarding the Pn geometrical spreading rate. The data consist of 77 Pn spectra, all amplitude-normalized using a set of previously measured spectral ratios of eastern Canadian earthquake sources. The normalization procedure eliminates the need for explicit source spectral assumptions, another common source of error in Pn attenuation measurements. An unconventional technique is introduced to account for differences in observed Pn spectra, which arise from geological site effects and instrument response error, both of which are frequency-dependent phenomena. We conclude that, at each frequency, the Pn amplitude falls off with distance according to: Δ−n, where Δ is epicentral distance. The exponent n is weakly frequency-dependent and takes the form: 2.2 + 0.02f. A unique interpretation of the behavior of the Pn spectral amplitude decay is unattainable, owing to the difficulty in separating the effects due to anelastic dissipation and the velocity structure in the uppermost mantle. It is interesting to note, however, that the spatial decay of pure elastic head waves follows the classical Δ−1/2L−3/2 relation, where L is the distance the waves travel in the mantle refractor. For the distance range of our interest (260-1087 km), this amounts to Δ−2.2. This indicates that towards low frequencies our n approaches a value which is consistent with the spatial decay rate expected of pure elastic head waves.
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Billinger, Sandra A., Jesse C. Craig, Sarah J. Kwapiszeski, Jason-Flor V. Sisante, Eric D. Vidoni, Rebecca Maletsky et David C. Poole. « Dynamics of middle cerebral artery blood flow velocity during moderate-intensity exercise ». Journal of Applied Physiology 122, no 5 (1 mai 2017) : 1125–33. http://dx.doi.org/10.1152/japplphysiol.00995.2016.
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The dynamic response to a stimulus such as exercise can reveal valuable insights into systems control in health and disease that are not evident from the steady-state perturbation. However, the dynamic response profile and kinetics of cerebrovascular function have not been determined to date. We tested the hypotheses that bilateral middle cerebral artery blood flow mean velocity (MCAV) increases exponentially following the onset of moderate-intensity exercise in 10 healthy young subjects. The MCAV response profiles were well fit to a delay (TD) + exponential (time constant, τ) model with substantial agreement for baseline [left (L): 69, right (R): 64 cm/s, coefficient of variation (CV) 11%], response amplitude (L: 16, R: 13 cm/s, CV 23%), TD (L: 54, R: 52 s, CV 9%), τ (L: 30, R: 30 s, CV 22%), and mean response time (MRT) (L: 83, R: 82 s, CV 8%) between left and right MCAV as supported by the high correlations (e.g., MRT r = 0.82, P < 0.05) and low CVs. Test-retest reliability was high with CVs for the baseline, amplitude, and MRT of 3, 14, and 12%, respectively. These responses contrasted markedly with those of three healthy older subjects in whom the MCAV baseline and exercise response amplitude were far lower and the kinetics slowed. A single older stroke patient showed baseline ipsilateral MCAV that was lower still and devoid of any exercise response whatsoever. We conclude that kinetics analysis of MCAV during exercise has significant potential to unveil novel aspects of cerebrovascular function in health and disease. NEW & NOTEWORTHY Resolution of the dynamic stimulus-response profile provides a greater understanding of the underlying the physiological control processes than steady-state measurements alone. We report a novel method of measuring cerebrovascular blood velocity (MCAv) kinetics under ecologically valid conditions from rest to moderate-intensity exercise. This technique reveals that brain blood flow increases exponentially following the onset of exercise with 1) a strong bilateral coherence in young healthy individuals, and 2) a potential for unique age- and disease-specific profiles.
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Elimelech, Yossef. « Temperature-Sensitive Paint Visualization of the Transitional Separation Bubble over Wings at Reynolds Numbers of Several Ten Thousand ». International Journal of Micro Air Vehicles 4, no 4 (décembre 2012) : 273–89. http://dx.doi.org/10.1260/1756-8293.4.4.273.
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Flow fields characterized by chord-based Reynolds numbers of several ten thousand over wings of conventional cross sections are analyzed below. Utilizing temperature-sensitive paint visualization and constant-temperature anemometry the results depict a laminar-to-turbulent transition process that develops over the wings. The visualizations were utilized in order to obtain the proper length scales which characterized the transition process and to allow effective use of the constant-temperature anemometry. Not only did the constant-temperature anemometry yielded a quantitative velocity measurement in the volume over the wings, it also complemented the low spectral resolution which characterized the visualization technique. Both experimental techniques depicted the evolution of stationary cellular flow structures over the wings along the transition process. These cellular flow structures were reported in recent publications and are associated with closed separation bubbles which are subjected to flow disturbances of finite amplitude. The volumetric time-accurate velocity measurements showed that the number of cellular flow structures was function of the wing aspect ratio; moreover, it allowed proper interpretation of the temperature-sensitive paint visualizations in regions of high velocity standard deviation.
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Hore, J., S. Watts et D. Tweed. « Errors in the control of joint rotations associated with inaccuracies in overarm throws ». Journal of Neurophysiology 75, no 3 (1 mars 1996) : 1013–25. http://dx.doi.org/10.1152/jn.1996.75.3.1013.
Texte intégralRésumé :
1. Accurate overarm throwing requires precise control of joint rotations so that the ball is released at the appropriate time on the appropriate hand trajectory. Inaccuracy in throws, in turn, must result from errors in the control of joint rotations. But do high and low throws result from disorders in the joint rotations that produce the hand trajectory or in those that cause ball release? Are they due to error at a particular joint or to accumulation of errors across a number of joints? The objective was to answer these questions and thereby to gain insight into the CNS control of joint rotations in a skilled arm movement task. 2. Ten subjects--male, right-handed recreational ball players, all accurate throwers--sat with a fixed trunk and threw tennis balls at a 9 x 9 grid of 6-cm target squares 1.5 or 3 m away. Rotations of five arm segments in three dimensions were measured at 1,000 Hz with the magnetic-field search-coil technique. Hand trajectory (translation) was computed from these rotations. 3. The cause of ball high-low inaccuracy was investigated by determining its relation with hand kinematic parameters that could potentially affect it. No statistically significant relation was found between height of ball impact on the target and height of the hand trajectory. In contrast, statistically significant relations appeared between height of ball impact on the target and both hand trajectory length at ball release (for 8 of 10 subjects) and finger and hand orientation in space at ball release (for all 10 subjects). 4. Three hypotheses were proposed to explain the variable finger and hand orientations in space at ball release, i.e., that they resulted from errors in velocity of rotation at one or more proximal joints (wrist, elbow, shoulder), timing of onset of rotation at one or more proximal joints, or timing of ball release (due to incorrect velocity or timing of onset of finger opening). All three mechanisms could result in inappropriate finger and hand orientations in space at ball release, but the pattern of joint space trajectories would be different in each case. 5. High and low throws did not follow the joint space paths predicted by the first two hypotheses. Instead, as predicted by the third hypothesis, a separation of traces occurred when finger extension was plotted against wrist flexion or against elbow extension, e.g., for a given amplitude of wrist flexion, finger extension was large for the high throws and small for the low throws. 6. In agreement, when all throws were considered, a statistically significant (P < 0.005) relation was found between ball impact height on the target and the amplitude of finger extension, for a fixed amplitude of wrist flexion (10 subjects), and for a fixed amplitude of elbow extension (8 subjects). Only two subjects showed a statistically significant relation between ball impact height and the amplitude of wrist flexion, for a fixed amplitude of elbow extension. 7. The separation of finger extension-wrist flexion traces in joint space for high and low throws was due to a difference in the timing of onset of finger rotation with respect to the wrist rather than to an inappropriate velocity of the finger (or the wrist). 8. As expected, all 10 subjects showed statistically significant relations between the time of onset of finger extension and both finger orientation in space at ball release and height of ball impact on the target. 9. It is concluded that in fast arm-only throws made by male recreational ball players, high and low throws do not primarily result from variability in the height of the hand trajectory or from variability in the amplitude of one or more proximal joints due to errors in the velocity or timing of onset of these joint rotations. Instead, in most cases, they result from inappropriate timing of onset of rotation of the fingers with respect to the rotations of the other joints and thus to inappropriate timing of ball release. These findings emphasize the im
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Bearman, P. W., M. J. Downie, J. M. R. Graham et E. D. Obasaju. « Forces on cylinders in viscous oscillatory flow at low Keulegan-Carpenter numbers ». Journal of Fluid Mechanics 154 (mai 1985) : 337–56. http://dx.doi.org/10.1017/s0022112085001562.
Texte intégralRésumé :
This paper presents a comparison between theory and experiment for the in-line forces on cylinders of general cross-section in planar oscillatory flows of small amplitude. The theoretical analysis evaluates corrections to the standard inviscid inertial force at low Keulegan-Carpenter numbers which arise from the presence of viscous laminar boundary layers and from the development of vortex shedding. The boundary-layer contribution due to both skin friction and displacement effects is calculated to first order in the Stokes parameter β−½. The contribution to the in-line force from separation and vortex shedding, for which the results presented only apply to sharp-edged bodies, is taken from previous work on vortex shedding from isolated edges using the discrete vortex modelling technique. The resulting force has components both in phase with the fluid acceleration (inertia) and in phase with the velocity (drag).The theoretical results are compared to measurements taken in a [xcup ]-tube water channel on a number of cylinders of different cross-section including circular cylinders and sharp-edged sections. The comparisons suggest that the theory is valid for Keulegan–Carpenter numbers below about 3 and for moderately high values of the β parameter.
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Miyanawala, T. P., et R. K. Jaiman. « Decomposition of wake dynamics in fluid–structure interaction via low-dimensional models ». Journal of Fluid Mechanics 867 (28 mars 2019) : 723–64. http://dx.doi.org/10.1017/jfm.2019.140.
Texte intégralRésumé :
We present a dynamic decomposition analysis of the wake flow in fluid–structure interaction (FSI) systems under both laminar and turbulent flow conditions. Of particular interest is to provide the significance of low-dimensional wake flow features and their interaction dynamics to sustain the free vibration of a square cylinder at a relatively low mass ratio. To obtain the high-dimensional data, we employ a body-conforming variational FSI solver based on the recently developed partitioned iterative scheme and the dynamic subgrid-scale turbulence model for a moderate Reynolds number ($Re$). The snapshot data from high-dimensional FSI simulations are projected to a low-dimensional subspace using the proper orthogonal decomposition (POD). We utilize each corresponding POD mode to detect features of the organized motions, namely, the vortex street, the shear layer and the near-wake bubble. We find that the vortex shedding modes contribute solely to the lift force, while the near-wake and shear layer modes play a dominant role in the drag force. We further examine the fundamental mechanism of this dynamical behaviour and propose a force decomposition technique via low-dimensional approximation. To elucidate the frequency lock-in, we systematically analyse the decomposed modes and their dynamical contributions to the force fluctuations for a range of reduced velocity at low Reynolds number laminar flow. These quantitative mode energy contributions demonstrate that the shear layer feeds the vorticity flux to the wake vortices and the near-wake bubble during the wake–body synchronization. Based on the decomposition of wake dynamics, we suggest an interaction cycle for the frequency lock-in during the wake–body interaction, which provides the interrelationship between the high-amplitude motion and the dominating wake features. Through our investigation of wake–body synchronization below critical $Re$ range, we discover that the bluff body can undergo a synchronized high-amplitude vibration due to flexibility-induced unsteadiness. Owing to the wake turbulence at a moderate Reynolds number of $Re=22\,000$, a distorted set of POD modes and the broadband energy distribution are observed, while the interaction cycle for the wake synchronization is found to be valid for the turbulent wake flow.
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Yang, In Young, Kwang Hee Im, David K. Hsu, Sung Jin Song, Hyeon Cho, Sun Kyu Kim, Young Hwan Seo et Je Woong Park. « Ultrasonic Inspection of Carbon/ Phenolic Composites Using a Peak-Delay Measurement Method ». Key Engineering Materials 321-323 (octobre 2006) : 889–92. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.889.
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Carbon/phenolic composite (CPC) materials are unique which consist of carbon fibers embedded in a carbon matrix. The CPCs are originally developed for aerospace applications and its low density, high thermal conductivity and excellent mechanical properties at elevated temperatures make it an ideal material for aircraft brake disks. The properties of the CPC are dependent on the manufacturing methods used for production and fiber arrangement. It is desirable to perform nondestructive evaluation to assess material properties and part homogeneity in order to ensure product quality and structural integrity of CPC brake disks. In this work, a CPC material was nondestructively characterized and a technique was developed to measure ultrasonic velocity in C/P composites using automated data acquisition software. Also a motorized system was adopted to measure ultrasonic velocity on the point of CPC materials under the same coupling conditions. Manual results were compared with those obtained by the motorized system with using drycoupling ultrasonics and through transmission method in immersion. A peak-delay measurement method well corresponded to ultrasonic velocities of the pulse overlap method and throughtransmission mode and C-scan image signal based on peak-to-peak amplitude.
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SUTHERLAND, BRUCE R., STUART B. DALZIEL, GRAHAM O. HUGHES et P. F. LINDEN. « Visualization and measurement of internal waves by ‘synthetic schlieren’. Part 1. Vertically oscillating cylinder ». Journal of Fluid Mechanics 390 (10 juillet 1999) : 93–126. http://dx.doi.org/10.1017/s0022112099005017.
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We present measurements of the density and velocity fields produced when an oscillating circular cylinder excites internal gravity waves in a stratified fluid. These measurements are obtained using a novel, non-intrusive optical technique suitable for determining the density fluctuation field in temporally evolving flows which are nominally two-dimensional. Although using the same basic principles as conventional methods, the technique uses digital image processing in lieu of large and expensive parabolic mirrors, thus allowing more flexibility and providing high sensitivity: perturbations of the order of 1% of the ambient density gradient may be detected. From the density gradient field and its time derivative it is possible to construct the perturbation fields of density and horizontal and vertical velocity. Thus, in principle, momentum and energy fluxes can be determined.In this paper we examine the structure and amplitude of internal gravity waves generated by a cylinder oscillating vertically at different frequencies and amplitudes, paying particular attention to the role of viscosity in determining the evolution of the waves. In qualitative agreement with theory, it is found that wave motions characterized by a bimodal displacement distribution close to the source are attenuated by viscosity and eventually undergo a transition to a unimodal displacement distribution further from the source. Close quantitative agreement is found when comparing our results with the theoretical ones of Hurley & Keady (1997). This demonstrates that the new experimental technique is capable of making accurate measurements and also lends support to analytic theories. However, theory predicts that the wave beams are narrower than observed, and the amplitude is significantly under-predicted for low-frequency waves. The discrepancy occurs in part because the theory neglects the presence of the viscous boundary layers surrounding the cylinder, and because it does not take into account the effects of wave attenuation resulting from nonlinear wave–wave interactions between the upward and downward propagating waves near the source.
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Owens, Edward F., Brent S. Russell, Ronald S. Hosek, Stephanie G. B. Sullivan, Lydia L. Dever et Linda Mullin. « Changes in adjustment force, speed, and direction factors in chiropractic students after 10 weeks undergoing standard technique training ». Journal of Chiropractic Education 32, no 1 (1 mars 2017) : 3–9. http://dx.doi.org/10.7899/jce-173.
Texte intégralRésumé :
Objective: To assess the force profiles of high-velocity low-amplitude thrusts delivered to a mannequin on a force platform by novice students given only verbal instructions. Methods: Student volunteers untrained in adjusting delivered a series of adjustments to a mannequin on a force platform. Participants performed 3 light, 3 normal, and 3 heavy thrusts on 5 listings specifying contact point, hand, and direction. Force profiles were analyzed for speed and amplitude, consistency, and force discrimination. Two recording sessions occurred 10 weeks apart. Results: Sixteen participants (11 females, 5 male) completed the study. Peak forces ranged from 880 to 202 N for heavy thrusts and 322- to 66 N for light thrusts. Thrust rate was from 8.1 to 1.8 Newtons per millisecond. Average coefficients of variability (CV = STD/mean) at each load level (initial/final) were heavy: 17%/15%; normal: 16%/15%; and light: 20%/20%, with 0 as ideal. A force ratio measured students' abilities to distinguish thrust magnitude. The heavy/normal ratio (initial/final) was 1.35/1.39, and the light/normal ratio was 0.70/0.67. Conclusions: At this point, without force feedback being used in the classroom, novice students can produce thrusts that look like those of their teachers and of experienced practitioners, but they may not produce similar speed and force values. They are consistent within and between sessions and can discriminate between light and heavy loads. A natural next step in our educational research will be to measure adjustment factors on more experienced cohorts of students with and without the presence of force-feedback training apparatus.
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Balamurugan, G., et A. C. Mandal. « Experiments on localized secondary instability in bypass boundary layer transition ». Journal of Fluid Mechanics 817 (16 mars 2017) : 217–63. http://dx.doi.org/10.1017/jfm.2017.92.
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An experimental study on localized secondary instability of unsteady streamwise streaks in bypass boundary layer transition under an elevated level of free-stream turbulence has been carried out mainly using the particle image velocimetry (PIV) technique. Simultaneous orthogonal dual-plane PIV measurements were performed for a concurrent examination of the transitional flow features in both wall-normal and spanwise planes. These quantitative and simultaneous visualizations clearly show the wall-normal view of a low-speed streak undergoing sinuous/varicose motion in the spanwise plane. An oscillating shear layer in the wall-normal plane is found to be associated with the sinuous/varicose streak oscillation in the spanwise plane. Further, these measurements indicate that a localized secondary instability wavepacket can originate near the boundary layer edge. The time-resolved PIV measurements in the wall-normal plane clearly show how an instability develops on a lifted-up inclined shear layer and leads to flow breakdown. The estimated wavelength and convection velocity of such instabilities are found to compare well with those calculated from the one-dimensional linear stability analysis of the spatially averaged velocity profiles associated with the lifted-up shear layers. The time-resolved PIV measurements in the spanwise plane also facilitate quantitative visualizations of sinuous and varicose instabilities. These measurements experimentally confirm that a varicose instability at the juncture of an incoming high-speed streak and a downstream low-speed streak can eventually lead to the formation of lambda structures. The estimated convection velocity, wavelength and growth rate of these instabilities are found to be consistent with the numerical results reported in the literature. Moreover, the streak secondary instability is found to be apparent in the velocity contours, while the estimated streak amplitude is approximately 30 % of the free-stream velocity.
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Zhang, Zhenghao, Yongteng Zhong et Jiawei Xiang. « TAM and MUSIC Approach for Impact-Source Localization under Deformation Conditions ». Sensors 20, no 11 (2 juin 2020) : 3151. http://dx.doi.org/10.3390/s20113151.
Texte intégralRésumé :
As an impact-source-localization technique, Lamb waves are commonly used to detect low-velocity impact in composite structures. However, the performance of Lamb waves is susceptible under deformation conditions. In this paper, a novel approach combined the Toeplitz approximation method (TAM) and multiple-signal classification (MUSIC) (TAM-MUSIC) to improve impact-source-localization (angle and distance in polar coordinates) accuracy under deformation conditions. The method divided a two-dimensional search of direction and distance into two one-dimensional searches. The impact direction was calculated by the TAM, which was introduced into the steering vector of MUSIC to estimate the distance by scanning the whole monitoring area. An epoxy laminate plate experiment showed that the phase and amplitude of uniform linear-array signals had different average plate curvature that led to poor impact-source-localization accuracy using the MUSIC method. TAM provided high-resolution direction-finding capability, suitable for the pretreatment of Lamb waves. Results showed that the present method, with a small amount of computation and low memory requirement, had higher location-estimation accuracy than that of traditional methods under deformation conditions.
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Dobreci, Lucian Daniel, Valentin Zichil, Elena Nechita, Cosmin Constantin Grigoraș et Vlad Andrei Ciubotariu. « Extracorporeal Shockwave Applicator for Spinal Pain and Muscular Contracture : A New Design Approach ». Applied Sciences 10, no 23 (4 décembre 2020) : 8710. http://dx.doi.org/10.3390/app10238710.
Texte intégralRésumé :
Shockwave therapy is a noninvasive treatment technique used in multidisciplinary fields, such as sports medicine, physical therapy, and orthopedics. This method of treatment is recommended for medical conditions, such as muscle contractions, intramuscular hematoma, or Dupuytren’s contracture. The shockwaves are high-energy pressure waves characterized by nonlinearity, high frequency, and peak pressure followed by low-pressure amplitude which are transmitted through an applicator to the affected tissue. In the case of spinal muscles, the conventional applicator can only be used on one side of the spinal cord at a time. Taking this into consideration, the approach suggested in this paper involves the design of a dedicated dual-tip applicator. This process implied predesign, finite element analysis, statistical analysis of the data, and optimization. We analyzed the input factors, such as frequency, pressure, applicator tip distance, shape, flatness, and material along with their effects, namely induced stress, tissue contact pressure, total strain energy, and propagation velocity. The proposed final design of the applicator uses geometric features suggested by the optimization analysis and also mechanical design features.