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1.
Int J Sports Med ; 43(6): 526-532, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-34555858

RESUMEN

This study aimed to investigate the impact of COVID-19 enforced prolonged training disruption and shortened competitive season, on in-season injury and illness rates. Injury incidence and percent proportion was calculated for the 2020 elite men's senior domestic cricket season and compared to a historical average from five previous regular seasons (2015 to 2019 inclusive). The injury profile for the shortened 2020 season was generally equivalent to what would be expected in a regular season, except for a significant increase in medical illness as a proportion of time loss (17% compared to historic average of 6%) and in-season days lost (9% compared to historic average of 3%) due to COVID-19 related instances (most notably precautionary isolation due to contact with a confirmed or suspected COVID-19 case). There was a significant increase in the proportion of in-season days lost to thigh injuries (24% compared to 9%) and a significant decrease in the proportion of days lost to hand (4% compared to 12%) and lumbar spine (7% compared to 21%) injuries. These findings enhance understanding of the impact prolonged period of training disruption and shortened season can have on cricket injuries and the challenges faced by practitioners under such circumstances.


Asunto(s)
Traumatismos en Atletas , COVID-19 , Traumatismos de la Pierna , Traumatismos en Atletas/epidemiología , COVID-19/epidemiología , Humanos , Incidencia , Masculino , Estaciones del Año
2.
Harm Reduct J ; 16(1): 52, 2019 08 30.
Artículo en Inglés | MEDLINE | ID: mdl-31470876

RESUMEN

There is limited literature about how to best "do" community involvement in research and no one model of community involvement in research that has been shown to be more effective than others. This paper presents one way to receive the input of people with experiences relevant to research with marginalised groups, including people who use and inject drugs. The UNSW Community Reference Panel is a virtual network of people from across Australia who are engaged to provide input and consultation on research design, processes, materials, and outputs. Although this panel goes some way towards community involvement and consultation in the research process, it does not take the place of other aspects of community governance and ownership, especially as informed by principles of research with Indigenous peoples. This model is an example of a means to bring the voices and perspectives of people who are generally excluded from the research and decision-making structures that affect their lives, including people who inject drugs, to influence the questions that are asked in research, how research gets done, and to what purpose research findings are put.


Asunto(s)
Investigación Participativa Basada en la Comunidad/organización & administración , Grupo Paritario , Abuso de Sustancias por Vía Intravenosa/rehabilitación , Participación de la Comunidad/psicología , Toma de Decisiones , Hepatitis C/psicología , Hepatitis C/rehabilitación , Humanos , Nueva Gales del Sur , Derivación y Consulta/organización & administración , Marginación Social , Abuso de Sustancias por Vía Intravenosa/psicología
3.
J Sci Med Sport ; 27(1): 25-29, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37953165

RESUMEN

OBJECTIVES: Explore whether injury profiles and mechanisms differ between red (First-Class multi-day) ball cricket and white (One-Day and Twenty20 limited over) ball cricket in elite men's domestic cricket from 2010 to 2019. DESIGN: Retrospective cohort analysis. METHODS: Injury incidence calculated according to the updated international consensus statement on injury surveillance in cricket, along with seasonal days lost and injury severity descriptive statistics. RESULTS: Across both cricket types, bowling resulted in the most seasonal days lost (mean 1942, 95 % confidence interval: 1799-2096) and highest mean injury severity (30 days, 95 % confidence interval: 28-33), with the lumbar spine the body region with the most seasonal days lost (mean 432 seasonal days; 95 % confidence interval: 355-525) from bowling. Injury incidence was higher in white ball compared to red ball cricket (per unit of time), with bowling (and its various phases) the most frequently occurring mechanism in both cricket types (white ball: 67.0 injuries per 1000 days of play [95 % confidence interval: 59.6-75.3]; red ball: 32.4 injuries per 1000 days of play [95 % confidence interval: 29.1-36.1]). When bowling, the abdomen and thigh were the body regions most injured from white (13.4 injuries per 1000 days of play [95 % confidence interval: 10.3-17.4]), and red ball (6.4 injuries per 1000 days of play [95 % confidence interval: 5.0-8.2]) cricket respectively. Overall, clear differences emerged in the nature and mechanism of injuries between red ball cricket and white ball cricket. CONCLUSIONS: Bowling presents the highest injury risk (across both cricket types), as well as highlighting the increased risk of injuries from diving during fielding and running between the wickets when batting, in shorter white ball cricket.


Asunto(s)
Traumatismos en Atletas , Críquet , Gryllidae , Carrera , Masculino , Animales , Humanos , Traumatismos en Atletas/epidemiología , Traumatismos en Atletas/etiología , Estudios Retrospectivos
4.
BMJ Open Sport Exerc Med ; 10(1): e001815, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38268523

RESUMEN

Objectives: To describe the injury profile of a novel format cricket competition ('The Hundred') and compare injury incidence and prevalence between the men's and women's competitions. Methods: Medical staff prospectively collected injury data from the eight men's and women's teams during the 2021-2023 competitions. Injury definitions and incidence calculations followed the international consensus statement. Results: In the men's competition, 164 injuries were recorded, compared with 127 in the women's competition. Tournament injury incidence was 36.6 (95% CI 31.4 to 42.7) and 32.5 (95% CI 27.3 to 38.7)/100 players/tournament in the men's and women's competition, respectively. Non-time-loss incidence (men's 26.6 (95% CI 22.2 to 31.8), women's 24.6 (95% CI 20.1 to 30.0)/100 players/tournament) was higher than time-loss incidence (men's 10.0 (95% CI 7.5 to 13.5), women's 7.9 (95% CI 5.6 to 11.3)/100 players/tournament). Injury prevalence was 2.9% and 3.6% in the men's and women's competitions, respectively. Match fielding was the most common activity at injury in both competitions. The thigh and hand were the most common body location time-loss injury in the men's and women's competitions, respectively. Conclusion: A similar injury profile was observed between the men's and women's competition. Preventative strategies targeting thigh injuries in the men's competition and hand injuries in the women's competition would be beneficial. Compared with published injury rates, 'The Hundred' men's presents a greater risk of injury than Twenty20 (T20), but similar to one-day cricket, with 'The Hundred' women's presenting a similar injury risk to T20 and one-day cricket. Additional years of data are required to confirm these findings.

5.
J Sci Med Sport ; 25(6): 474-479, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35246382

RESUMEN

OBJECTIVES: Describe hamstring injury incidence across competition formats, activity at time of injury, and time of season, facilitating the identification of injury risk factors in elite men's senior First-Class County Cricket. DESIGN: Prospective cohort. METHODS: Hamstring time loss injury incidence (between format, activity, and time of season) calculated for elite men's senior First-Class County Cricket seasons 2010 to 2019. RESULTS: The diagnosis with the highest seasonal incidence was 'Biceps femoris strain grade 1-2' (2.5 injuries/100 players). Hamstring injury incidence was highest in One-Day cricket (mean 27.2 injuries/1000 team days). Running between wickets when batting was the activity associated with the highest incidence in the shorter competition formats (8.4 and 4.8 injuries/1000 team days for One-Day and T20, respectively). Bowling delivery stride or follow through was the activity with the highest incidence for longer multi-day Test format (mean 2.3 injuries/1000 team days), although similar incidence was observed across all formats for this activity. Most injuries were sustained at the start of the season (April; 22.7 injuries/1000 team days), with significantly fewer injuries at end of the season (September; 4.1 injuries/1000 team days). CONCLUSIONS: Similar bowling injury incidence across formats suggests hamstring injury risk is associated more with the activity itself, whereas injury risk when batting was susceptible to changes in match intensity. The notably higher (albeit non-significant) incidence in April may allude to a lack of preparedness to meet the physical demands of the start of the season. The findings have practical relevance for practitioners, identifying potential opportunities for preventative strategies.


Asunto(s)
Traumatismos en Atletas , Traumatismos de la Pierna , Traumatismos de los Tejidos Blandos , Traumatismos en Atletas/epidemiología , Traumatismos en Atletas/etiología , Humanos , Incidencia , Traumatismos de la Pierna/epidemiología , Masculino , Prevalencia , Estudios Prospectivos , Gales/epidemiología
6.
Undersea Hyperb Med ; 38(3): 175-85, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-21721351

RESUMEN

We have previously conducted and reported on the primary endpoint of a clinical study which demonstrated that hyperbaric oxygen (HBO2) preconditioning consisting of two 30-minute intervals of 100% oxygen at 2.4 atmospheres absolute (ATA) prior to coronary artery bypass graft (CABG) surgery leads to an improvement in left ventricular stroke work (LVSW) 24 hours following CABG. In that study, 81 patients were randomized to treatment with HBO2 (HBO2; n = 41) or routine treatment (Control Group; n = 40) prior to surgery. The objective of this manuscript is to further report on the result of the exploratory secondary endpoints from that study, specifically the effects of HBO2 preconditioning on biomarkers of myocardial protection. Intraoperative right atrial biopsies were assessed, via an Enzyme Linked ImmunoSorbent Assay (ELISA), for the expression of eNOS and HSP72. In this study, no significant differences were observed between the groups with respect to the quantity of myocardial eNOS and HSP72. However, in the HBO2 Group, following ischemia and reperfusion, the quantities of myocardial eNOS and HSP72 were increased. This suggests that HBO2 preconditioning in this group of patients may be capable of inducing endogenous cardioprotection following ischemic reperfusion injury (IRI).


Asunto(s)
Puente de Arteria Coronaria , Proteínas del Choque Térmico HSP72/análisis , Oxigenoterapia Hiperbárica , Precondicionamiento Isquémico Miocárdico/métodos , Miocardio/química , Óxido Nítrico Sintasa de Tipo III/análisis , Adulto , Anciano , Anciano de 80 o más Años , Biomarcadores/análisis , Biopsia , Atrios Cardíacos/química , Atrios Cardíacos/patología , Humanos , Persona de Mediana Edad , Isquemia Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/prevención & control , Estudios Prospectivos , Informe de Investigación , Adulto Joven
7.
J Sci Med Sport ; 23(9): 836-840, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32303476

RESUMEN

OBJECTIVES: This study primarily aimed to explore injury incidence rates in the three main domestic competition formats in England and Wales (First-Class, One-Day and Twenty20 [T20]). For the first time, the study also describes the epidemiology of elite men's domestic cricket injuries across nine seasons (2010-2018 inclusive). DESIGN: Prospective cohort analysis. METHODS: Injury incidence and prevalence from all injuries calculated according to the updated international consensus statement on injury surveillance in cricket, with statistical process control charts (SPC) used to detect trends in the data. RESULTS: The average match injury incidence was 102 injuries/1000 days of play, with highest incidence in One-Day (254 injuries/1000 days of play), followed by T20 (136 injuries/1000 days of play) and First-Class Cricket (68 injuries/1000 days of play). Most match injuries were sustained during bowling (41.6 injuries/1000 days of play), followed by fielding (26.8 injuries/1000 days of play) and batting (22.3 injuries/1000 days of play). The thigh was the body area most commonly injured (7.4 injuries/100 players per season), with lumbar spine injuries the most prevalent (1.3% of players unavailable on any given day during the season). On average, 7.5% of players were unavailable on any given day during the domestic season when all injuries were considered (match and training). The SPC charts showed relatively consistent match injury incidence for all competitions, reproduced across all nine seasons. CONCLUSION: These findings provide a robust empirical base for the extent of the injury problem in domestic cricket played in England and Wales, with similar injury profiles across the three formats.


Asunto(s)
Traumatismos en Atletas/epidemiología , Críquet/lesiones , Inglaterra/epidemiología , Humanos , Incidencia , Masculino , Prevalencia , Estudios Prospectivos , Gales/epidemiología
8.
J Surg Res ; 149(1): 155-64, 2008 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17996900

RESUMEN

Ischemic reperfusion injury (IRI) is an inevitable part cardiac surgery such as coronary artery bypass graft (CABG). While ischemic hypoxia and the ensuing normoxic or hyperoxic reperfusion are critical to the initiation and propagation of IRI, conditioning myocardial cells to an oxidative stress prior to IRI may limit the consequences of this injury. Hyperbaric oxygen (HBO2) is a modality of treatment that is known to generate an oxidative stress. Studies have shown that treatment with HBO2 postischemia and reperfusion is useful in ameliorating myocardial IRI. Moreover, preconditioning the myocardium with HBO2 before reperfusion has demonstrated a myocardial protective effect by limiting the infarct size post ischemia and reperfusion. Current evidence suggests that HBO2 preconditioning may partly attenuate IRI by stimulating the endogenous production of nitric oxide (NO). As NO has the capacity to reduce neutrophil sequestration, adhesion and associated injury, and improve vascular flow, HBO2 preconditioning induced NO may play a role in providing myocardial protection during interventions that involve an inevitable episode of IRI. This current opinion review article attempts to suggest that HBO2 may be used to pharmacologically precondition and protect the myocardium from the effects of IRI that is known to occur during cardiac surgery.


Asunto(s)
Oxigenoterapia Hiperbárica , Precondicionamiento Isquémico Miocárdico/métodos , Daño por Reperfusión Miocárdica/terapia , Óxido Nítrico/metabolismo , Animales , Procedimientos Quirúrgicos Cardíacos/efectos adversos , Humanos , Daño por Reperfusión Miocárdica/etiología , Daño por Reperfusión Miocárdica/metabolismo , Ratas
9.
Eur J Cardiothorac Surg ; 32(4): 623-8, 2007 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-17689969

RESUMEN

BACKGROUND: Operative mortality is comparatively higher for coronary artery bypass grafting (CABG) or valve reoperations. Studies of reoperative risk have focussed on surgical techniques. We sought to determine the risk and predictors of poor outcome in current practice, and the influence of preoperative symptoms. METHOD: For every redo patient (n=289), we selected the best-matched pair of patients who underwent a primary operation (n=578) between 1998 and 2006. Matching variables were age, gender, left ventricular ejection fraction (LVEF) and type of operation. Poor outcome was defined as operative mortality or major morbidity. RESULT: Median age was 68 (interquartile range 62-73) years and 28% were female for both groups. Severe symptoms and cardiac morbidity dominated the presentation of redo patients. CABG (53%), valve repair/replacement (34%) and combined CABG and valve (12%) were performed with overall operative mortality of 6.6% (median additive EuroScore 7.0) for redo versus 1.6% (median additive EuroScore 4.0) for primary groups (p<.0001). Whereas no significant difference was observed between primary (1.6%) and redo CABG (3.9%, p=.19), valve reoperations had higher operative mortality (9.6% vs 1.5%, p<.0001). Major complications occurred more frequently after redo valve compared to primary valve operations (28% vs 14%, p=.001). Reoperation (odds ratio [OR] 1.26, 95% confidence interval [CI] 0.66-2.42, p=.48) was not a predictor of major adverse event after CABG or valve surgery. Determinants of poor outcome after valve reoperations were New York Heart Association class III/IV (OR 6.86, 95% CI 2.29-12.11, p=.03), duration of extracorporeal circulation (OR 1.17, 95% CI 1.02-1.35, p=.03) and mitral valve replacement (OR 4.07, 95% CI 1.83-36.01, p=.04). The predictors of major adverse events after redo CABG were congestive heart failure (OR 1.85, 95% CI 1.04-8.98, p=.006) chronic obstructive pulmonary disease (OR 17.5, 95% CI 1.87-35.21, p=.05) and interval from prior surgery (OR 1.37, 95% CI 1.09-1.92, p=.01). CONCLUSION: In the current era, redo CABG is nearly as safe as the primary operation. A valve reoperation, on the contrary, is higher risk due, partly, to severe symptoms at presentation. Patients should be referred and operated on early before they develop severe symptoms.


Asunto(s)
Puente de Arteria Coronaria/mortalidad , Enfermedad Coronaria/cirugía , Anciano , Puente de Arteria Coronaria/métodos , Enfermedad Coronaria/complicaciones , Enfermedad Coronaria/mortalidad , Femenino , Implantación de Prótesis de Válvulas Cardíacas/efectos adversos , Implantación de Prótesis de Válvulas Cardíacas/mortalidad , Humanos , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Complicaciones Posoperatorias/etiología , Complicaciones Posoperatorias/mortalidad , Derivación y Consulta , Reoperación/mortalidad , Factores de Riesgo , Índice de Severidad de la Enfermedad , Resultado del Tratamiento
10.
Adv Ther ; 24(1): 106-18, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17526467

RESUMEN

Heart failure (HF) is a chronic condition that is expected to increase in incidence along with increased life expectancy and an aging population. As the incidence of HF increases, the cost to national healthcare budgets is expected to run into the billions. The costs of lost productivity and increased social reliance on state support must also be considered. Recently, acute myocardial infarction (AMI) has come to be seen as the major contributing factor to HF. Although thrombolysis may restore coronary perfusion after an AMI, it may also introduce ischemic reperfusion injury (IRI). In an attempt to ameliorate sustained protein damage caused by IRI, endogenous chaperone proteins known as heat shock proteins (HSPs) are induced as a consequence of the stress of IRI. Recently, hyperbaric oxygen has been shown to induce the production of HSPs in noncardiac tissue, with a resultant protective effect. This current opinion review article suggests a possible role for hyperbaric oxygen, as a technologically modern drug, in augmenting the induction of endogenous HSPs to repair and improve the function of failing hearts that have been damaged by AMI and IRI. In addition, this simple, safe, noninvasive drug may prove useful in easing the economic burden of HF on already overextended health resources.


Asunto(s)
Insuficiencia Cardíaca/terapia , Proteínas de Choque Térmico/biosíntesis , Oxigenoterapia Hiperbárica , Animales , Terapia Combinada , Insuficiencia Cardíaca/etiología , Insuficiencia Cardíaca/metabolismo , Humanos , Infarto del Miocardio/complicaciones , Ensayos Clínicos Controlados Aleatorios como Asunto
11.
Adv Ther ; 23(4): 528-33, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-17050495

RESUMEN

Over the years, the anecdotal medical use of oxygen has demonstrated, in a non-evidence-based manner, that it may have wide-ranging clinical consequences. Although oxygen is a critical substrate in the alleviation of hypoxia, anoxia, and ischemia, paradoxically, it also functions as a deleterious metabolite during the reperfusion of previously ischemic tissues. In adding to this controversy, a spate of new pioneering work has identified hyperoxygenation (hyperoxia) and its metabolites as solely and purposefully demonstrating cellular and clinical benefit,particularly in the field of ischemic reperfusion injury (IRI). Furthermore, the beneficial effects of oxygen have been technologically augmented by administration at doses above atmospheric pressure and at higher concentrations. The novel technology that involves oxygen treatment at supra-atmospheric pressures in high concentrations is known as hyperbaric oxygen (HBO). Although the concept of hyperbaric oxygen has been around since the mid 20th century, it is only during the past decade or so that its therapeutic potential as a new technology-based drug has been exploited for the purposes of cellular tolerance and protection. HBO has recently been shown to be a useful adjunct in several models of IRI, including myocardial infarction. How it does this remains to be elucidated. This article attempts to bring into the spotlight some pertinent developments regarding HBO and myocardial IRI, while simultaneously stimulating intellect, thought, and discussion as to whether this novel technology--HBO--which consists of only a singular drug--oxygen--is a therapy that warrants further laboratory and clinical investigation as a therapeutic modality that may be safe and cost-effective, without producing significant adverse effects.


Asunto(s)
Oxigenoterapia Hiperbárica , Daño por Reperfusión Miocárdica/terapia , Animales , Ensayos Clínicos como Asunto , Humanos
12.
Cardiovasc Revasc Med ; 7(3): 146-54, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-16945821

RESUMEN

Ischemia-reperfusion injury (IRI) occurs following coronary artery revascularization. Reactive oxygen species (ROS) were initially thought to play a role in the pathogenesis of this injury. However, the evidence for this is inconclusive. Recent studies involving ischemic preconditioning have identified ROS as potential mediators for the cardioprotective effects observed following this technique. Furthermore, cardiac studies involving IRI and the use of hyperbaric oxygen (HBO) have demonstrated the ability of HBO to induce cardioprotection and to attenuate IRI. This review suggests the possible role for HBO as a new drug in the arena of myocardial revascularization and cellular protection. While there is mounting clinical evidence for this, a methodological understanding of HBO's cellular mechanisms of actions appears to be lacking. As such, this article attempts to draw the similarity between HBO and other protective oxidative stress mechanisms and then to speculate in an evidence-based manner its possible cellular mechanistic role as a drug via the generation of ROS.


Asunto(s)
Oxigenoterapia Hiperbárica , Mediadores de Inflamación/metabolismo , Daño por Reperfusión Miocárdica/terapia , Revascularización Miocárdica , Especies Reactivas de Oxígeno/metabolismo , Animales , Adhesión Celular , Humanos , Peroxidación de Lípido , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/fisiopatología , Daño por Reperfusión Miocárdica/prevención & control , Neutrófilos/metabolismo , Estrés Oxidativo
14.
Cardiovasc Revasc Med ; 11(1): 8-19, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20129356

RESUMEN

OBJECTIVE: The objective of this study was to determine whether preconditioning coronary artery disease (CAD) patients with HBO(2) prior to first-time elective on-pump cardiopulmonary bypass (CPB) coronary artery bypass graft surgery (CABG) leads to improved myocardial left ventricular stroke work (LVSW) post CABG. The primary end point of this study was to demonstrate that preconditioning CAD patients with HBO(2) prior to on-pump CPB CABG leads to a statistically significant (P<.05) improvement in myocardial LVSW 24 h post CABG. METHODS: This randomised control study consisted of 81 (control group=40; HBO(2) group=41) patients who had CABG using CPB. Only the HBO(2) group received HBO(2) preconditioning for two 30-min intervals separated 5 min apart. HBO(2) treatment consisted of 100% oxygen at 2.4 ATA. Pulmonary artery catheters were used to obtain perioperative hemodynamic measurements. All routine perioperative clinical outcomes were recorded. Venous blood was taken pre HBO(2), post HBO(2) (HBO(2) group only), and during the perioperative period for analysis of troponin T. RESULTS: Prior to CPB, the HBO(2) group had significantly lower pulmonary vascular resistance (P=.03). Post CPB, the HBO(2) group had increased stroke volume (P=.01) and LVSW (P=.005). Following CABG, there was a smaller rise in troponin T in HBO(2) group suggesting that HBO(2) preconditioning prior to CABG leads to less postoperative myocardial injury. Post CABG, patients in the HBO(2) group had an 18% (P=.05) reduction in length of stay in the intensive care unit (ICU). Intraoperatively, the HBO(2) group had a 57% reduction in intraoperative blood loss (P=.02). Postoperatively, the HBO(2) group had a reduction in blood loss (11.6%), blood transfusion (34%), low cardiac output syndrome (10.4%), inotrope use (8%), atrial fibrillation (11%), pulmonary complications (12.7%), and wound infections (7.6%). Patients in the HBO(2) group saved US$116.49 per ICU hour. CONCLUSION: This study met its primary end point and demonstrated that preconditioning CAD patients with HBO(2) prior to on-pump CPB CABG was capable of improving LVSW. Additionally, this study also showed that HBO(2) preconditioning prior to CABG reduced myocardial injury, intraoperative blood loss, ICU length of stay, postoperative complications, and saved on cost, post CABG.


Asunto(s)
Puente de Arteria Coronaria , Cardiopatías/prevención & control , Oxigenoterapia Hiperbárica , Unidades de Cuidados Intensivos , Función Ventricular Izquierda , Anciano , Biomarcadores/sangre , Pérdida de Sangre Quirúrgica/prevención & control , Puente Cardiopulmonar , Cateterismo de Swan-Ganz , Puente de Arteria Coronaria/efectos adversos , Puente de Arteria Coronaria/economía , Análisis Costo-Beneficio , Procedimientos Quirúrgicos Electivos , Femenino , Cardiopatías/sangre , Cardiopatías/economía , Cardiopatías/etiología , Hemodinámica , Costos de Hospital , Humanos , Oxigenoterapia Hiperbárica/economía , Unidades de Cuidados Intensivos/economía , Tiempo de Internación , Masculino , Cuidados Preoperatorios , Recuperación de la Función , Volumen Sistólico , Factores de Tiempo , Resultado del Tratamiento , Troponina T/sangre
15.
J Acoust Soc Am ; 113(6): 3188-96, 2003 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-12822791

RESUMEN

Smart structures technology can be applied to amplified acoustic guitars to prevent instability resulting from acoustic feedback. This work presents a coupled model of the guitar dynamics and the acoustic feedback mechanism, and explains how a simple control loop using a piezoelectric ceramic actuator can be used to reduce the effects of acoustic feedback. In addition to model simulations, experimental results using a real system and a simple controller are presented. The results show that a significantly higher (7 dB) guitar output can be achieved before instability, without detrimentally affecting the amplified and unamplified guitar response.

16.
J Acoust Soc Am ; 111(1 Pt 1): 174-9, 2002 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11831792

RESUMEN

In many active noise control applications, it is necessary that acoustic actuators be mounted in small enclosures due to volume constraints and in order to remain unobtrusive. However, the air spring of the enclosure is detrimental to the low-frequency performance of the actuator. For launch vehicle noise control applications, mass and volume constraints are very limiting, but the low-frequency performance of the actuator is critical. This work presents a novel approach that uses a nonlinear buckling suspension system and partial evacuation of the air within the enclosure to yield a compact, sealed acoustic driver that exhibits a very low natural frequency. Linear models of the device are presented and numerical simulations are given to illustrate the advantages of this design concept. An experimental prototype was built and measurements indicate that this design can significantly improve the low-frequency response of compact acoustic actuators.


Asunto(s)
Acústica , Modelos Teóricos , Vehículos a Motor , Ruido/prevención & control , Humanos , Ruido/efectos adversos
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