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Sample records for mechanical chest compressions

  1. Mechanical chest compressions in the coronary catheterization laboratory - do not hesitate to go step further!

    PubMed

    Bělohlávek, Jan; Kovárník, Tomáš

    2016-01-01

    Authors Wagner et al. in your journal demonstrated effectiveness of mechanical chest compressions in the coronary catheterization laboratory to facilitate coronary intervention and survival in patients requiring prolonged resuscitation efforts. We dare to comment on this article and advocate to use mechanical chest compressions only as a bridge to extracorporeal membrane oxygenation to completely substitute failed circulation and enable percutaneous coronary intervention or other procedures to treat the cause of cardiac arrest. PMID:27530540

  2. Technique for chest compressions in adult CPR

    PubMed Central

    2011-01-01

    Chest compressions have saved the lives of countless patients in cardiac arrest as they generate a small but critical amount of blood flow to the heart and brain. This is achieved by direct cardiac massage as well as a thoracic pump mechanism. In order to optimize blood flow excellent chest compression technique is critical. Thus, the quality of the delivered chest compressions is a pivotal determinant of successful resuscitation. If a patient is found unresponsive without a definite pulse or normal breathing then the responder should assume that this patient is in cardiac arrest, activate the emergency response system and immediately start chest compressions. Contra-indications to starting chest compressions include a valid Do Not Attempt Resuscitation Order. Optimal technique for adult chest compressions includes positioning the patient supine, and pushing hard and fast over the center of the chest with the outstretched arms perpendicular to the patient's chest. The rate should be at least 100 compressions per minute and any interruptions should be minimized to achieve a minimum of 60 actually delivered compressions per minute. Aggressive rotation of compressors prevents decline of chest compression quality due to fatigue. Chest compressions are terminated following return of spontaneous circulation. Unconscious patients with normal breathing are placed in the recovery position. If there is no return of spontaneous circulation, then the decision to terminate chest compressions is based on the clinical judgment that the patient's cardiac arrest is unresponsive to treatment. Finally, it is important that family and patients' loved ones who witness chest compressions be treated with consideration and sensitivity. PMID:22152601

  3. Mechanical versus manual chest compressions for out-of-hospital cardiac arrest: a meta-analysis of randomized controlled trials.

    PubMed

    Tang, Lu; Gu, Wan-Jie; Wang, Fei

    2015-01-01

    Recent evidence regarding mechanical chest compressions in out-of-hospital cardiac arrest (OHCA) is conflicting. The objective of this study was to perform a meta-analysis of randomized controlled trials (RCTs) to compare the effect of mechanical versus manual chest compressions on resuscitation outcomes in OHCA. PubMed, Embase, the Cochrane Central Register of Controlled Trials, and the ClinicalTrials.gov registry were searched. In total, five RCTs with 12,510 participants were included. Compared with manual chest compressions, mechanical chest compressions did not significantly improve survival with good neurological outcome to hospital discharge (relative risks (RR) 0.80, 95% CI 0.61-1.04, P = 0.10; I(2) = 65%), return of spontaneous circulation (RR 1.02, 95% CI 0.95-1.09, P = 0.59; I(2) = 0%), or long-term (≥6 months) survival (RR 0.96, 95% CI 0.79-1.16, P = 0.65; I(2) = 16%). In addition, mechanical chest compressions were associated with worse survival to hospital admission (RR 0.94, 95% CI 0.89-1.00, P = 0.04; I(2) = 0%) and to hospital discharge (RR 0.88, 95% CI 0.78-0.99, P = 0.03; I(2) = 0%). Based on the current evidence, widespread use of mechanical devices for chest compressions in OHCA cannot be recommended. PMID:26503429

  4. Device Assists Cardiac Chest Compression

    NASA Technical Reports Server (NTRS)

    Eichstadt, Frank T.

    1995-01-01

    Portable device facilitates effective and prolonged cardiac resuscitation by chest compression. Developed originally for use in absence of gravitation, also useful in terrestrial environments and situations (confined spaces, water rescue, medical transport) not conducive to standard manual cardiopulmonary resuscitation (CPR) techniques.

  5. Mechanical Chest Compressions in Prolonged Cardiac Arrest due to ST Elevation Myocardial Infarction Can Cause Myocardial Contusion.

    PubMed

    Stechovsky, Cyril; Hajek, Petr; Cipro, Simon; Veselka, Josef

    2016-09-01

    Acute coronary syndrome is a common cause of sudden cardiac death. We present a case report of a 60-year-old man without a history of coronary artery disease who presented with ST-elevation myocardial infarction. During transportation to the hospital, he developed ventricular fibrillation (VF) and later pulseless electrical activity. Chest compressions with LUCAS 2 (Medtronic, Minneapolis, MN) automated mechanical compression-decompression device were initiated. Coronary angiography showed total occlusion of the left main coronary artery and primary percutaneous coronary intervention (PCI) was performed. After the PCI, his heart started to generate effective contractions and LUCAS could be discontinued. Return of spontaneous circulation was achieved after 90 minutes of cardiac arrest. The patient died of cardiogenic shock 11 hours later. An autopsy revealed a transmural anterolateral myocardial infarction but also massive subepicardial hemorrhage and interstitial edema and hemorrhages on histologic samples from regions of the myocardium outside the infarction itself and also from the right ventricle. These lesions were concluded to be a myocardial contusion. The true incidence of myocardial contusion as a consequence of mechanical chest compressions is not known. We speculate that severe myocardial contusion might have influenced outcome of our patient. PMID:27574387

  6. Compression of digital chest x-rays

    NASA Astrophysics Data System (ADS)

    Cohn, Michael; Trefler, Martin; Young, Tzay S.

    1990-07-01

    The application of digital technologies to chest radiography holds the promise of routine application of intage processing techniques to effect image enhancement. However, due to their inherent spatial resolution, digital chest images impose severe constraints on data storage devices. Compression of these images will relax such constraints and facilitate image transmission on a digital network. We have evaluated image processing algorithms aimed at compression of digital chest images while improving the diagnostic quality of the image. The image quality has been measured with respect to the task of tumor detection. Compression ratios of as high as 2:1 have been achieved. This compression can then be supplemented by irreversible methods.

  7. Enhancement and compression of digital chest radiographs.

    PubMed

    Cohn, M; Trefler, M; Young, T Y

    1990-01-01

    The application of digital technologies to chest radiography holds the promise of routine application of image processing techniques to effect image enhancement. Because of their inherent spatial resolution, however, digital chest images impose severe constraints on data storage devices. Compression of these images will relax such constraints and facilitate image transmission on a digital network. We evaluated an algorithm for enhancing digital chest images that has allowed significant data compression while improving the diagnostic quality of the image. This algorithm is based on the photographic technique of unsharp masking. Image quality was measured with respect to the task of tumor detection and compression ratios as high as 2:1 were achieved. This compression can be supplemented by irreversible methods. PMID:2299708

  8. Chest compression with a higher level of pressure support ventilation: effects on secretion removal, hemodynamics, and respiratory mechanics in patients on mechanical ventilation*

    PubMed Central

    Naue, Wagner da Silva; Forgiarini, Luiz Alberto; Dias, Alexandre Simões; Vieira, Silvia Regina Rios

    2014-01-01

    OBJECTIVE: To determine the efficacy of chest compression accompanied by a 10-cmH2O increase in baseline inspiratory pressure on pressure support ventilation, in comparison with that of aspiration alone, in removing secretions, normalizing hemodynamics, and improving respiratory mechanics in patients on mechanical ventilation. METHODS: This was a randomized crossover clinical trial involving patients on mechanical ventilation for more than 48 h in the ICU of the Porto Alegre Hospital de Clínicas, in the city of Porto Alegre, Brazil. Patients were randomized to receive aspiration alone (control group) or compression accompanied by a 10-cmH2O increase in baseline inspiratory pressure on pressure support ventilation (intervention group). We measured hemodynamic parameters, respiratory mechanics parameters, and the amount of secretions collected. RESULTS: We included 34 patients. The mean age was 64.2 ± 14.6 years. In comparison with the control group, the intervention group showed a higher median amount of secretions collected (1.9 g vs. 2.3 g; p = 0.004), a greater increase in mean expiratory tidal volume (16 ± 69 mL vs. 56 ± 69 mL; p = 0.018), and a greater increase in mean dynamic compliance (0.1 ± 4.9 cmH2O vs. 2.8 ± 4.5 cmH2O; p = 0.005). CONCLUSIONS: In this sample, chest compression accompanied by an increase in pressure support significantly increased the amount of secretions removed, the expiratory tidal volume, and dynamic compliance. (ClinicalTrials.gov Identifier:NCT01155648 [http://www.clinicaltrials.gov/]) PMID:24626270

  9. Factors modulating effective chest compressions in the neonatal period.

    PubMed

    Mildenhall, Lindsay F J; Huynh, Trang K

    2013-12-01

    The need for chest compressions in the newborn is a rare occurrence. The methods employed for delivery of chest compressions have been poorly researched. Techniques that have been studied include compression:ventilation ratios, thumb versus finger method of delivering compressions, depth of compression, site on chest of compression, synchrony or asynchrony of breaths with compressions, and modalities to improve the compression technique and consistency. Although still in its early days, an evidence-based guideline for chest compressions is beginning to take shape. PMID:23920076

  10. Effect of the rate of chest compression familiarised in previous training on the depth of chest compression during metronome-guided cardiopulmonary resuscitation: a randomised crossover trial

    PubMed Central

    Bae, Jinkun; Chung, Tae Nyoung; Je, Sang Mo

    2016-01-01

    Objectives To assess how the quality of metronome-guided cardiopulmonary resuscitation (CPR) was affected by the chest compression rate familiarised by training before the performance and to determine a possible mechanism for any effect shown. Design Prospective crossover trial of a simulated, one-person, chest-compression-only CPR. Setting Participants were recruited from a medical school and two paramedic schools of South Korea. Participants 42 senior students of a medical school and two paramedic schools were enrolled but five dropped out due to physical restraints. Intervention Senior medical and paramedic students performed 1 min of metronome-guided CPR with chest compressions only at a speed of 120 compressions/min after training for chest compression with three different rates (100, 120 and 140 compressions/min). Friedman's test was used to compare average compression depths based on the different rates used during training. Results Average compression depths were significantly different according to the rate used in training (p<0.001). A post hoc analysis showed that average compression depths were significantly different between trials after training at a speed of 100 compressions/min and those at speeds of 120 and 140 compressions/min (both p<0.001). Conclusions The depth of chest compression during metronome-guided CPR is affected by the relative difference between the rate of metronome guidance and the chest compression rate practised in previous training. PMID:26873050

  11. Comparison of chest compression quality between the modified chest compression method with the use of smartphone application and the standardized traditional chest compression method during CPR.

    PubMed

    Park, Sang-Sub

    2014-01-01

    The purpose of this study is to grasp difference in quality of chest compression accuracy between the modified chest compression method with the use of smartphone application and the standardized traditional chest compression method. Participants were progressed 64 people except 6 absentees among 70 people who agreed to participation with completing the CPR curriculum. In the classification of group in participants, the modified chest compression method was called as smartphone group (33 people). The standardized chest compression method was called as traditional group (31 people). The common equipments in both groups were used Manikin for practice and Manikin for evaluation. In the meantime, the smartphone group for application was utilized Android and iOS Operating System (OS) of 2 smartphone products (G, i). The measurement period was conducted from September 25th to 26th, 2012. Data analysis was used SPSS WIN 12.0 program. As a result of research, the proper compression depth (mm) was shown the proper compression depth (p< 0.01) in traditional group (53.77 mm) compared to smartphone group (48.35 mm). Even the proper chest compression (%) was formed suitably (p< 0.05) in traditional group (73.96%) more than smartphone group (60.51%). As for the awareness of chest compression accuracy, the traditional group (3.83 points) had the higher awareness of chest compression accuracy (p< 0.001) than the smartphone group (2.32 points). In the questionnaire that was additionally carried out 1 question only in smartphone group, the modified chest compression method with the use of smartphone had the high negative reason in rescuer for occurrence of hand back pain (48.5%) and unstable posture (21.2%). PMID:24704648

  12. [Closed-loop control for chest compression based on coronary perfusion pressure: a computer simulation study].

    PubMed

    Chen, Aihua; Gao, Lei; Tian, Linhuai; Zhang, Jian; Zhan, Ningbo

    2014-08-01

    In this study, a closed-loop controller for chest compression which adjusts chest compression depth according to the coronary perfusion pressure (CPP) was proposed. An effective and personalized chest compression method for automatic mechanical compression devices was provided, and the traditional and uniform chest compression standard neglecting individual difference was improved. This study rebuilds Charles F. Babbs human circulation model with CPP simulation module and proposes a closed-loop controller based on a fuzzy control algorithm. The performance of the fuzzy controller was evaluated and compared to that of a traditional PID controller in computer simulation studies. The simulation results demonstrated that the fuzzy closed-loop controller produced shorter regulation time, fewer oscillations and smaller overshoot than those of the traditional PID controller and outperforms the traditional PID controller in CPP regulation and maintenance. PMID:25464812

  13. [Closed-loop control for chest compression based on coronary perfusion pressure: a computer simulation study].

    PubMed

    Chen, Aihua; Gao, Lei; Tian, Linhuai; Zhang, Jian; Zhan, Ningbo

    2014-08-01

    In this study, a closed-loop controller for chest compression which adjusts chest compression depth according to the coronary perfusion pressure (CPP) was proposed. An effective and personalized chest compression method for automatic mechanical compression devices was provided, and the traditional and uniform chest compression standard neglecting individual difference was improved. This study rebuilds Charles F. Babbs human circulation model with CPP simulation module and proposes a closed-loop controller based on a fuzzy control algorithm. The performance of the fuzzy controller was evaluated and compared to that of a traditional PID controller in computer simulation studies. The simulation results demonstrated that the fuzzy closed-loop controller produced shorter regulation time, fewer oscillations and smaller overshoot than those of the traditional PID controller and outperforms the traditional PID controller in CPP regulation and maintenance. PMID:25508443

  14. Supine chest compression: alternative to prone ventilation in acute respiratory distress syndrome.

    PubMed

    Samanta, Sukhen; Samanta, Sujay; Soni, Kapil Dev

    2014-05-01

    Prone ventilation is usually used for severe acute respiratory distress syndrome. We applied an alternative method to prone position. We described 2 cases of trauma where prone position could not be done. Chest wall compression was performed by 2-kg weight in front of the chest wall bilaterally while the patient was in a supine position. Respiratory mechanics work to improve oxygenation almost as same as the mechanism proposed for prone position without any major adverse effects and serious complications. We suggest a larger randomized study to determine the efficacy and also to find out the optimum weight required to compress the chest. PMID:24332252

  15. Relationship of blood pressure and flow during CPR to chest compression amplitude: evidence for an effective compression threshold.

    PubMed

    Babbs, C F; Voorhees, W D; Fitzgerald, K R; Holmes, H R; Geddes, L A

    1983-09-01

    This study was conducted to investigate the importance of the depth of chest compression in producing effective cardiopulmonary resuscitation (CPR) in animals, as indicated by cardiac output and mean arterial blood pressure. Cardiac output was measured by a modified indicator dilution technique in 8 anesthetized dogs, 6 to 12 kg body weight, during repeated 2-minute episodes of electrically induced ventricular fibrillation and CPR provided by a mechanical chest compressor and ventilator (Thumper). Chest compression exceeding a threshold value (xo) between 1.5 and 3.0 cm was required in each animal to produce measurable cardiac output. In particular, cardiac output (CO) was linearly related to chest compression depth (x) by an expression of the form CO = a(x-xo) for x greater than xo. The mean value of xo was 2.3 cm. A similar threshold for measurable blood pressure was observed in 7 of the 8 dogs, with a mean value of 1.8 cm. For chest compression of 2.5 cm or greater, relatively modest increases in chest compression depth caused relatively large changes in cardiac output. PMID:6614604

  16. Chest Compression-Only CPR: A Meta-Analysis

    PubMed Central

    Hüpfl, Michael; Selig, Harald F; Nagele, Peter

    2010-01-01

    Summary Background Evidence suggests that dispatcher-assisted chest compression-only bystander CPR may be superior to standard CPR (chest compressions and rescue ventilation) in out-of-hospital cardiac arrest, yet recent clinical trials did not observe improved outcomes. The goal of the study was to determine the association between chest compression-only CPR and survival after out-of-hospital cardiac arrest. Methods Studies published until August 2010 were systematically searched and identified in MEDLINE and EMBASE databases. For the primary meta-analysis only clinical trials were included that prospectively randomized dispatcher instructions to chest compression-only versus standard bystander CPR in out-of-hospital adult cardiac arrest patients; for the secondary meta-analysis observational cohort studies were included that distinguished between standard CPR and chest compression-only CPR. All studies were required to contain survival data. Data on study characteristics, methods and outcomes (return of spontaneous circulation, survival to discharge, 30-day survival, and favourable neurologic outcome) were extracted. A fixed-effects model was used for both meta-analyses for lack of heterogeneity among the studies (I2 0%). Findings All three published randomized clinical trials were included in the meta-analysis. The pooled analyses shows that dispatcher-assisted chest compression-only bystander CPR for adult out-of-hospital cardiac arrest was associated with a 22% improved chance of survival (risk ratio [RR] 1.22 [95% confidence interval {CI}, 1.01 – 1.47]; I2, 0%) compared to standard CPR. The absolute increase in survival was 2.4%; the number needed to treat was 41. The secondary meta-analysis included seven observational studies of bystander-CPR (not dispatcher-assisted) and showed no difference between the two CPR techniques (RR, 0.96 [95% CI, 0.83 – 1.11]; I2, 0%). Interpretation Dispatcher-assisted chest compression-only bystander CPR is associated with

  17. Closed-loop controller for chest compressions based on coronary perfusion pressure: a computer simulation study.

    PubMed

    Wang, Chunfei; Zhang, Guang; Wu, Taihu; Zhan, Ningbo; Wang, Yaling

    2016-03-01

    High-quality cardiopulmonary resuscitation contributes to cardiac arrest survival. The traditional chest compression (CC) standard, which neglects individual differences, uses unified standards for compression depth and compression rate in practice. In this study, an effective and personalized CC method for automatic mechanical compression devices is provided. We rebuild Charles F. Babbs' human circulation model with a coronary perfusion pressure (CPP) simulation module and propose a closed-loop controller based on a fuzzy control algorithm for CCs, which adjusts the CC depth according to the CPP. Compared with a traditional proportion-integration-differentiation (PID) controller, the performance of the fuzzy controller is evaluated in computer simulation studies. The simulation results demonstrate that the fuzzy closed-loop controller results in shorter regulation time, fewer oscillations and smaller overshoot than traditional PID controllers and outperforms the traditional PID controller for CPP regulation and maintenance. PMID:26142111

  18. Effect of gravity on chest wall mechanics.

    PubMed

    Bettinelli, D; Kays, C; Bailliart, O; Capderou, A; Techoueyres, P; Lachaud, J L; Vaïda, P; Miserocchi, G

    2002-02-01

    Chest wall mechanics was studied in four subjects on changing gravity in the craniocaudal direction (G(z)) during parabolic flights. The thorax appears very compliant at 0 G(z): its recoil changes only from -2 to 2 cmH(2)O in the volume range of 30-70% vital capacity (VC). Increasing G(z) from 0 to 1 and 1.8 G(z) progressively shifted the volume-pressure curve of the chest wall to the left and also caused a fivefold exponential decrease in compliance. For lung volume <30% VC, gravity has an inspiratory effect, but this effect is much larger going from 0 to 1 G(z) than from 1 to 1.8 G(z). For a volume from 30 to 70% VC, the effect is inspiratory going from 0 to 1 G(z) but expiratory from 1 to 1.8 G(z). For a volume greater than approximately 70% VC, gravity always has an expiratory effect. The data suggest that the chest wall does not behave as a linear system when exposed to changing gravity, as the effect depends on both chest wall volume and magnitude of G(z). PMID:11796685

  19. Simulation analysis of three intubating supraglottic devices during infant chest compression.

    PubMed

    Kohama, Hanako; Komasawa, Nobuyasu; Ueki, Ryusuke; Kaminoh, Yoshiroh; Nishi, Shin-ichi

    2015-01-01

    Current guidelines for pediatric cardiopulmonary resuscitation suggest that supraglottic devices are alternatives for tracheal intubation with minimal interruption of chest compression. We examined the utility of three intubating supraglottic devices, air-Q® (air-Q), Ambu® aura-i (aura-i), and i-gel® (i-gel), utilizing manikin simulation. Twenty-two novice physicians performed securing of airway on an infant manikin with the three devices. We measured the rate of success on ventilation and the insertion time with or without chest compression. Successful ventilation rate did not significantly decrease with chest compression in the three devices (without chest compression: air-Q, 21/22; aura-i, 20/22; i-gel, 20/22, during chest compression: air-Q, 20/22; aura-i, 20/22; i-gel, 18/22). The insertion time with air-Q and aura-i did not extend significantly for chest compression. In contrast, the insertion time with i-gel was significantly extended in chest compression (P < 0.05). Air-Q and aura-i are more useful for airway management during chest compression than i-gel. PMID:25711262

  20. Chest Compression With Personal Protective Equipment During Cardiopulmonary Resuscitation

    PubMed Central

    Chen, Jie; Lu, Kai-Zhi; Yi, Bin; Chen, Yan

    2016-01-01

    Abstract Following a chemical, biological, radiation, and nuclear incident, prompt cardiopulmonary resuscitation (CPR) procedure is essential for patients who suffer cardiac arrest. But CPR when wearing personal protection equipment (PPE) before decontamination becomes a challenge for healthcare workers (HCW). Although previous studies have assessed the impact of PPE on airway management, there is little research available regarding the quality of chest compression (CC) when wearing PPE. A present randomized cross-over simulation study was designed to evaluate the effect of PPE on CC performance using mannequins. The study was set in one university medical center in the China. Forty anesthesia residents participated in this randomized cross-over study. Each participant performed 2 min of CC on a manikin with and without PPE, respectively. Participants were randomized into 2 groups that either performed CC with PPE first, followed by a trial without PPE after a 180-min rest, or vice versa. CPR recording technology was used to objectively quantify the quality of CC. Additionally, participants’ physiological parameters and subjective fatigue score values were recorded. With the use of PPE, a significant decrease of the percentage of effective compressions (41.3 ± 17.1% with PPE vs 67.5 ± 15.6% without PPE, P < 0.001) and the percentage of adequate compressions (67.7 ± 18.9% with PPE vs 80.7 ± 15.5% without PPE, P < 0.001) were observed. Furthermore, the increases in heart rate, mean arterial pressure, and subjective fatigue score values were more obvious with the use of PPE (all P < 0.01). We found significant deterioration of CC performance in HCW with the use of a level-C PPE, which may be a disadvantage for enhancing survival of cardiac arrest. PMID:27057878

  1. An algorithm used for ventricular fibrillation detection without interrupting chest compression.

    PubMed

    Li, Yongqin; Bisera, Joe; Weil, Max Harry; Tang, Wanchun

    2012-01-01

    Ventricular fibrillation (VF) is the primary arrhythmic event in the majority of patients suffering from sudden cardiac arrest. Attention has been focused on this particular rhythm since it is recognized that prompt therapy, especially electrical defibrillation, may lead to a successful outcome. However, current versions of automated external defibrillators (AEDs) mandate repetitive interruptions of chest compression for rhythm analyses since artifacts produced by chest compression during cardiopulmonary resuscitation (CPR) preclude reliable electrocardiographic (ECG) rhythm analysis. Yet, repetitive interruptions in chest compression are detrimental to the success of defibrillation. The capability for rhythm analysis without requiring "hands-off" intervals will allow for more effective resuscitation. In this paper, a novel continuous-wavelet-transformation-based morphology consistency evaluation algorithm was developed for the detection of disorganized VF from organized sinus rhythm (SR) without interrupting the ongoing chest compression. The performance of this method was evaluated on both uncorrupted and corrupted ECG signals recorded from AEDs obtained from out-of-hospital victims of cardiac arrest. A total of 232 patients and 31,092 episodes of either VF or SR were accessed, in which 8195 episodes were corrupted by artifacts produced by chest compressions. We also compared the performance of this method with three other established algorithms, including VF filter, spectrum analysis, and complexity measurement. Even though there was a modest decrease in specificity and accuracy when chest compression artifact was present, the performance of this method was still superior to other reported methods for VF detection during uninterrupted CPR. PMID:21342836

  2. Chest compressions in an infant with osteogenesis imperfecta type II: No new rib fractures.

    PubMed

    Sewell, R D; Steinberg, M A

    2000-11-01

    The case report of a newborn female with osteogenesis imperfecta type II who underwent cardiopulmonary resuscitation (CPR) with manual chest compressions for several minutes is presented. Chest radiographs taken before and after the chest compressions were administered were reviewed by several radiologists from 3 different hospitals and demonstrated no new radiographically visible rib fractures. Collagen analysis, the patient's clinical appearance, and clinical course, as well as a consultant's opinion aided in confirmation of the diagnosis of osteogenesis imperfecta type II. A review of 4 previous studies concerning rib fractures and CPR is included. This unique case supports previous articles that have concluded that rib fractures rarely, if ever, result from CPR in pediatrics, even in children with a lethal underlying bone disease, such as osteogenesis imperfecta type II. cardiopulmonary resuscitation, chest compressions, osteogenesis imperfecta, rib fractures, bone disease. PMID:11061808

  3. Chest compressions for bradycardia or asystole in neonates.

    PubMed

    Kapadia, Vishal; Wyckoff, Myra H

    2012-12-01

    When effective ventilation fails to establish a heart rate of greater than 60 bpm, cardiac compressions should be initiated to improve perfusion. The 2-thumb method is the most effective and least fatiguing technique. A ratio of 3 compressions to 1 breath is recommended to provide adequate ventilation, the most common cause of newborn cardiovascular collapse. Interruptions in compressions should be limited to not diminishing the perfusion generated. Oxygen (100%) is recommended during compressions and can be reduced once adequate heart rate and oxygen saturation are achieved. Limited clinical data are available to form newborn cardiac compression recommendations. PMID:23164181

  4. Influence of Chest Compressions on Circulation during the Peri-Cardiac Arrest Period in Porcine Models

    PubMed Central

    Li, Yan; Walline, Joseph; Zheng, Liangliang; Fu, Yangyang; Yao, Dongqi; Zhu, Huadong; Liu, Xiaohe; Chai, Yanfen; Wang, Zhong; Yu, Xuezhong

    2016-01-01

    Objective Starting chest compressions immediately after a defibrillation shock might be harmful, if the victim already had a return of spontaneous circulation (ROSC) and yet was still being subjected to external compressions at the same time. The objective of this study was to study the influence of chest compressions on circulation during the peri-cardiac arrest period. Design Prospective, randomized controlled study. Setting Animal experimental center in Peking Union Medical Collage Hospital, Beijing, China. Subjects Healthy 3-month-old male domestic pigs. Interventions 44 pigs (28±2 kg) were randomly assigned to three groups: Group I (non-arrested with compressions) (n = 12); Group II (arrested with compressions only) (n = 12); Group III (ROSC after compressions and defibrillation) (n = 20). In Groups I and II, compressions were performed to a depth of 5cm (Ia and IIa, n = 6) or a depth of 3cm (Ib and IIb, n = 6) respectively, while in Group III, the animals which had just achieved ROSC (n = 18) were compressed to a depth of 5cm (IIIa, n = 6), a depth of 3cm (IIIb, n = 6), or had no compressions (IIIc, n = 6). Hemodynamic parameters were collected and analyzed. Measurements and Findings Hemodynamics were statistically different between Groups Ia and Ib when different depths of compressions were performed (p < 0.05). In Group II, compressions were beneficial and hemodynamics correlated with the depth of compressions (p < 0.05). In Group III, compressions that continued after ROSC produced a reduction in arterial pressure (p < 0.05). Conclusions Chest compressions might be detrimental to hemodynamics in the early post-ROSC stage. The deeper the compressions were, the better the effect on hemodynamics during cardiac arrest, but the worse the effect on hemodynamics after ROSC. PMID:27168071

  5. Lung and chest wall mechanics in microgravity.

    PubMed

    Edyvean, J; Estenne, M; Paiva, M; Engel, L A

    1991-11-01

    We studied the effect of 15-20 s of weightlessness on lung, chest wall, and abdominal mechanics in five normal subjects inside an aircraft flying repeated parabolic trajectories. We measured flow at the mouth, thoracoabdominal and compartmental volume changes, and gastric pressure (Pga). In two subjects, esophageal pressures were measured as well, allowing for estimates of transdiaphragmatic pressure (Pdi). In all subjects functional residual capacity at 0 Gz decreased by 244 +/- 31 ml as a result of the inward displacement of the abdomen. End-expiratory Pga decreased from 6.8 +/- 0.8 cmH2O at 1 Gz to 2.5 +/- 0.3 cmH2O at Gz (P less than 0.005). Abdominal contribution to tidal volume increased from 0.33 +/- 0.05 to 0.51 +/- 0.04 at 0 Gz (P less than 0.001) but delta Pga showed no consistent change. Hence abdominal compliance increased from 43 +/- 9 to 70 +/- 10 ml/cmH2O (P less than 0.05). There was no consistent effect of Gz on tidal swings of Pdi, on pulmonary resistance and dynamic compliance, or on any of the timing parameters determining the temporal pattern of breathing. The results indicate that at 0 G respiratory mechanics are intermediate between those in the upright and supine postures at 1 G. In addition, analysis of end-expiratory pressures suggests that during weightlessness intra-abdominal pressure is zero, the diaphragm is passively tensed, and a residual small pleural pressure gradient may be present. PMID:1761497

  6. Effectiveness of chest compression feedback during cardiopulmonary resuscitation in lateral tilted and semirecumbent positions: a randomised controlled simulation study.

    PubMed

    Song, Y; Oh, J; Chee, Y; Cho, Y; Lee, S; Lim, T H

    2015-11-01

    Feedback devices have been shown to improve the quality of chest compression during cardiopulmonary resuscitation for patients in the supine position, but no studies have reported the effects of feedback devices on chest compression when the chest is tilted. Basic life support-trained providers were randomly assigned to administer chest compressions to a manikin in the supine, 30° left lateral tilt and 30° semirecumbent positions, with or without the aid of a feedback device incorporated into a smartphone. Thirty-six participants were studied. The feedback device did not affect the quality of chest compressions in the supine position, but improved aspects of performance in the tilted positions. In the lateral tilted position, the median (IQR [range]) chest compression rate was 99 (99-100 [96-117]) compressions.min(-1) with and 115 (95-128 [77-164]) compressions.min(-1) without feedback (p = 0.05), and the proportion of compressions of correct depth was 55 (0-96 [0-100])% with and 1 (0-30 [0-100])% without feedback (p = 0.03). In the semirecumbent position, the proportion of compressions of correct depth was 21 (0-87 [0-100])% with and 1 (0-26 [0-100])% without feedback (p = 0.05). Female participants applied chest compressions at a more accurate rate using the feedback device in the lateral tilted position but were unable to increase the chest compression depth, whereas male participants were able to increase the force of chest compression using the feedback device in the lateral tilted and semirecumbent positions. We conclude that a feedback device improves the application of chest compressions during simulated cardiopulmonary resuscitation when the chest is tilted. PMID:26349025

  7. Chest wall mechanics in sustained microgravity.

    PubMed

    Wantier, M; Estenne, M; Verbanck, S; Prisk, G K; Paiva, M

    1998-06-01

    We assessed the effects of sustained weightlessness on chest wall mechanics in five astronauts who were studied before, during, and after the 10-day Spacelab D-2 mission (n = 3) and the 180-day Euromir-95 mission (n = 2). We measured flow and pressure at the mouth and rib cage and abdominal volumes during resting breathing and during a relaxation maneuver from midinspiratory capacity to functional residual capacity. Microgravity produced marked and consistent changes (Delta) in the contribution of the abdomen to tidal volume [DeltaVab/(DeltaVab + DeltaVrc), where Vab is abdominal volume and Vrc is rib cage volume], which increased from 30.7 +/- 3. 5 (SE)% at 1 G head-to-foot acceleration to 58.3 +/- 5.7% at 0 G head-to-foot acceleration (P < 0.005). Values of DeltaVab/(DeltaVab + DeltaVrc) did not change significantly during the 180 days of the Euromir mission, but in the two subjects DeltaVab/(DeltaVab + DeltaVrc) was greater on postflight day 1 than on subsequent postflight days or preflight. In the two subjects who produced satisfactory relaxation maneuvers, the slope of the Konno-Mead plot decreased in microgravity; this decrease was entirely accounted for by an increase in abdominal compliance because rib cage compliance did not change. These alterations are similar to those previously reported during short periods of weightlessness inside aircrafts flying parabolic trajectories. They are also qualitatively similar to those observed on going from upright to supine posture; however, in contrast to microgravity, such postural change reduces rib cage compliance. PMID:9609801

  8. Chest wall mechanics in sustained microgravity

    NASA Technical Reports Server (NTRS)

    Wantier, M.; Estenne, M.; Verbanck, S.; Prisk, G. K.; Paiva, M.; West, J. B. (Principal Investigator)

    1998-01-01

    We assessed the effects of sustained weightlessness on chest wall mechanics in five astronauts who were studied before, during, and after the 10-day Spacelab D-2 mission (n = 3) and the 180-day Euromir-95 mission (n = 2). We measured flow and pressure at the mouth and rib cage and abdominal volumes during resting breathing and during a relaxation maneuver from midinspiratory capacity to functional residual capacity. Microgravity produced marked and consistent changes (Delta) in the contribution of the abdomen to tidal volume [DeltaVab/(DeltaVab + DeltaVrc), where Vab is abdominal volume and Vrc is rib cage volume], which increased from 30.7 +/- 3. 5 (SE)% at 1 G head-to-foot acceleration to 58.3 +/- 5.7% at 0 G head-to-foot acceleration (P < 0.005). Values of DeltaVab/(DeltaVab + DeltaVrc) did not change significantly during the 180 days of the Euromir mission, but in the two subjects DeltaVab/(DeltaVab + DeltaVrc) was greater on postflight day 1 than on subsequent postflight days or preflight. In the two subjects who produced satisfactory relaxation maneuvers, the slope of the Konno-Mead plot decreased in microgravity; this decrease was entirely accounted for by an increase in abdominal compliance because rib cage compliance did not change. These alterations are similar to those previously reported during short periods of weightlessness inside aircrafts flying parabolic trajectories. They are also qualitatively similar to those observed on going from upright to supine posture; however, in contrast to microgravity, such postural change reduces rib cage compliance.

  9. A Simulation-based Randomized Controlled Study of Factors Influencing Chest Compression Depth

    PubMed Central

    Mayrand, Kelsey P.; Fischer, Eric J.; Ten Eyck, Raymond P.

    2015-01-01

    Introduction Current resuscitation guidelines emphasize a systems approach with a strong emphasis on quality cardiopulmonary resuscitation (CPR). Despite the American Heart Association (AHA) emphasis on quality CPR for over 10 years, resuscitation teams do not consistently meet recommended CPR standards. The objective is to assess the impact on chest compression depth of factors including bed height, step stool utilization, position of the rescuer’s arms and shoulders relative to the point of chest compression, and rescuer characteristics including height, weight, and gender. Methods Fifty-six eligible subjects, including physician assistant students and first-year emergency medicine residents, were enrolled and randomized to intervention (bed lowered and step stool readily available) and control (bed raised and step stool accessible, but concealed) groups. We instructed all subjects to complete all interventions on a high-fidelity mannequin per AHA guidelines. Secondary end points included subject arm angle, height, weight group, and gender. Results Using an intention to treat analysis, the mean compression depths for the intervention and control groups were not significantly different. Subjects positioning their arms at a 90-degree angle relative to the sagittal plane of the mannequin’s chest achieved a mean compression depth significantly greater than those compressing at an angle less than 90 degrees. There was a significant correlation between using a step stool and achieving the correct shoulder position. Subject height, weight group, and gender were all independently associated with compression depth. Conclusion Rescuer arm position relative to the patient’s chest and step stool utilization during CPR are modifiable factors facilitating improved chest compression depth. PMID:26759667

  10. Detail view of steam chest and valve mechanisms for high ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view of steam chest and valve mechanisms for high pressure stage of unit 40. - Burnsville Natural Gas Pumping Station, Saratoga Avenue between Little Kanawha River & C&O Railroad line, Burnsville, Braxton County, WV

  11. Feedback on the Rate and Depth of Chest Compressions during Cardiopulmonary Resuscitation Using Only Accelerometers

    PubMed Central

    Ruiz de Gauna, Sofía; González-Otero, Digna M.; Ruiz, Jesus; Russell, James K.

    2016-01-01

    Background Quality of cardiopulmonary resuscitation (CPR) is key to increase survival from cardiac arrest. Providing chest compressions with adequate rate and depth is difficult even for well-trained rescuers. The use of real-time feedback devices is intended to contribute to enhance chest compression quality. These devices are typically based on the double integration of the acceleration to obtain the chest displacement during compressions. The integration process is inherently unstable and leads to important errors unless boundary conditions are applied for each compression cycle. Commercial solutions use additional reference signals to establish these conditions, requiring additional sensors. Our aim was to study the accuracy of three methods based solely on the acceleration signal to provide feedback on the compression rate and depth. Materials and Methods We simulated a CPR scenario with several volunteers grouped in couples providing chest compressions on a resuscitation manikin. Different target rates (80, 100, 120, and 140 compressions per minute) and a target depth of at least 50 mm were indicated. The manikin was equipped with a displacement sensor. The accelerometer was placed between the rescuer’s hands and the manikin’s chest. We designed three alternatives to direct integration based on different principles (linear filtering, analysis of velocity, and spectral analysis of acceleration). We evaluated their accuracy by comparing the estimated depth and rate with the values obtained from the reference displacement sensor. Results The median (IQR) percent error was 5.9% (2.8–10.3), 6.3% (2.9–11.3), and 2.5% (1.2–4.4) for depth and 1.7% (0.0–2.3), 0.0% (0.0–2.0), and 0.9% (0.4–1.6) for rate, respectively. Depth accuracy depended on the target rate (p < 0.001) and on the rescuer couple (p < 0.001) within each method. Conclusions Accurate feedback on chest compression depth and rate during CPR is possible using exclusively the chest

  12. A simple accurate chest-compression depth gauge using magnetic coils during cardiopulmonary resuscitation

    NASA Astrophysics Data System (ADS)

    Kandori, Akihiko; Sano, Yuko; Zhang, Yuhua; Tsuji, Toshio

    2015-12-01

    This paper describes a new method for calculating chest compression depth and a simple chest-compression gauge for validating the accuracy of the method. The chest-compression gauge has two plates incorporating two magnetic coils, a spring, and an accelerometer. The coils are located at both ends of the spring, and the accelerometer is set on the bottom plate. Waveforms obtained using the magnetic coils (hereafter, "magnetic waveforms"), which are proportional to compression-force waveforms and the acceleration waveforms were measured at the same time. The weight factor expressing the relationship between the second derivatives of the magnetic waveforms and the measured acceleration waveforms was calculated. An estimated-compression-displacement (depth) waveform was obtained by multiplying the weight factor and the magnetic waveforms. Displacements of two large springs (with similar spring constants) within a thorax and displacements of a cardiopulmonary resuscitation training manikin were measured using the gauge to validate the accuracy of the calculated waveform. A laser-displacement detection system was used to compare the real displacement waveform and the estimated waveform. Intraclass correlation coefficients (ICCs) between the real displacement using the laser system and the estimated displacement waveforms were calculated. The estimated displacement error of the compression depth was within 2 mm (<1 standard deviation). All ICCs (two springs and a manikin) were above 0.85 (0.99 in the case of one of the springs). The developed simple chest-compression gauge, based on a new calculation method, provides an accurate compression depth (estimation error < 2 mm).

  13. Clinical utility of wavelet compression for resolution-enhanced chest radiography

    NASA Astrophysics Data System (ADS)

    Andriole, Katherine P.; Hovanes, Michael E.; Rowberg, Alan H.

    2000-05-01

    This study evaluates the usefulness of wavelet compression for resolution-enhanced storage phosphor chest radiographs in the detection of subtle interstitial disease, pneumothorax and other abnormalities. A wavelet compression technique, MrSIDTM (LizardTech, Inc., Seattle, WA), is implemented which compresses the images from their original 2,000 by 2,000 (2K) matrix size, and then decompresses the image data for display at optimal resolution by matching the spatial frequency characteristics of image objects using a 4,000- square matrix. The 2K-matrix computed radiography (CR) chest images are magnified to a 4K-matrix using wavelet series expansion. The magnified images are compared with the original uncompressed 2K radiographs and with two-times magnification of the original images. Preliminary results show radiologist preference for MrSIDTM wavelet-based magnification over magnification of original data, and suggest that the compressed/decompressed images may provide an enhancement to the original. Data collection for clinical trials of 100 chest radiographs including subtle interstitial abnormalities and/or subtle pneumothoraces and normal cases, are in progress. Three experienced thoracic radiologists will view images side-by- side on calibrated softcopy workstations under controlled viewing conditions, and rank order preference tests will be performed. This technique combines image compression with image enhancement, and suggests that compressed/decompressed images can actually improve the originals.

  14. A Comparison of Chest Compression Quality Delivered During On-Scene and Ground Transport Cardiopulmonary Resuscitation

    PubMed Central

    Russi, Christopher S.; Myers, Lucas A.; Kolb, Logan J.; Lohse, Christine M.; Hess, Erik P.; White, Roger D.

    2016-01-01

    Introduction American Heart Association (AHA) guidelines recommend cardiopulmonary resuscitation (CPR) chest compressions 1.5 to 2 inches (3.75–5 cm) deep at 100 to 120 per minute. Recent studies demonstrated that manual CPR by emergency medical services (EMS) personnel is substandard. We hypothesized that transport CPR quality is significantly worse than on-scene CPR quality. Methods We analyzed adult patients receiving on-scene and transport chest compressions from nine EMS sites across Minnesota and Wisconsin from May 2008 to July 2010. Two periods were analyzed: before and after visual feedback. CPR data were collected and exported with the Zoll M series monitor and a sternally placed accelerometer measuring chest compression rate and depth. We compared compression data with 2010 AHA guidelines and Zoll RescueNet Code Review software. CPR depth and rate were “above (deep),” “in,” or “below (shallow)” the target range according to AHA guidelines. We paired on-scene and transport data for each patient; paired proportions were compared with the nonparametric Wilcoxon signed rank test. Results In the pre-feedback period, we analyzed 105 of 140 paired cases (75.0%); in the post-feedback period, 35 of 140 paired cases (25.0%) were analyzed. The proportion of correct depths during on-scene compressions (median, 41.9%; interquartile range [IQR], 16.1–73.1) was higher compared to the paired transport proportion (median, 8.7%; IQR, 2.7–48.9). Proportions of on-scene median correct rates and transport median correct depths did not improve in the post-feedback period. Conclusion Transport chest compressions are significantly worse than on-scene compressions. Implementation of visual real-time feedback did not affect performance. PMID:27625733

  15. Chest Compression Fraction Determines Survival in Patients with Out-of-hospital Ventricular Fibrillation

    PubMed Central

    Christenson, Jim; Andrusiek, Douglas; Everson-Stewart, Siobhan; Kudenchuk, Peter; Hostler, David; Powell, Judy; Callaway, Clifton W.; Bishop, Dan; Vaillancourt, Christian; Davis, Dan; Aufderheide, Tom P.; Idris, Ahamed; Stouffer, John A.; Stiell, Ian; Berg, Robert

    2009-01-01

    Background Quality CPR contributes to cardiac arrest survival. The proportion of time in which chest compressions are performed in each minute of CPR is an important modifiable aspect of quality CPR. We sought to estimate the effect of an increasing proportion of time spent performing chest compressions during cardiac arrest on survival to hospital discharge in patients with out-of hospital ventricular fibrillation or pulseless ventricular tachycardia. Methods and Results This is a prospective observational cohort study of adult patients from the Resuscitation Outcomes Consortium Cardiac Arrest Epistry with confirmed ventricular fibrillation or ventricular tachycardia, no defibrillation prior to emergency medical services arrival, electronically recorded cardiopulmonary resuscitation prior to the first shock and a confirmed outcome. Patients were followed to discharge from hospital or death. In the 506 cases, the mean age was 64 years, 80% were male, 71% were witnessed by a bystander, 51% received bystander cardiopulmonary resuscitation, 34% occurred in a public location, and 23% survived. After adjustment for age, gender, location, bystander cardiopulmonary resuscitation, bystander witness status, and response time the odds ratios of surviving to hospital discharge in the two highest categories of chest compression fraction compared to the reference category were 3.01 (95% CI, 1.37, 6.58) and 2.33 (95% CI, 0.96, 5.63). The estimated adjusted linear effect on odds ratio of survival for a 10% change in chest compression fraction was 1.11 (95% CI, 1.01, 1.21). Conclusion Increased chest compression fraction is independently predictive of better survival in patients suffering a prehospital ventricular fibrillation/tachycardia cardiac arrest. PMID:19752324

  16. Clinical evaluation of wavelet compression of digitized chest x-rays

    NASA Astrophysics Data System (ADS)

    Erickson, Bradley J.; Manduca, Armando; Persons, Kenneth R.

    1997-05-01

    In this paper we assess lossy image compression of digitalized chest x-rays using radiologist assessment of anatomic structures and numerical measurements of image accuracy. Forty chest x-rays were digitized and compressed using an irreversible wavelet technique at 10, 20, 40 and 80:1. These were presented in a blinded fashion with an uncompressed image for subjective A-B comparison of 11 anatomic structures as well as overall quality. Mean error, RMS error, maximum pixel error, and number of pixels within 1 percent of original value were also computed for compression ratios from 10:1 to 80:1. We found that at low compression there was a slight preference for compressed images. There was no significant difference at 20:1 and 40:1. There was a slight preference on some structures for the original compared with 80:1 compressed images. Numerical measures demonstrated high image faithfulness, both in terms of number of pixels that were within 1 percent of their original value, and by the average error for all pixels. Our findings suggest that lossy compression at 40:1 or more can be used without perceptible loss in the demonstration of anatomic structures.

  17. Assessment of low-contrast detectability for compressed digital chest images

    NASA Astrophysics Data System (ADS)

    Cook, Larry T.; Insana, Michael F.; McFadden, Michael A.; Hall, Timothy J.; Cox, Glendon G.

    1994-04-01

    The ability of human observers to detect low-contrast targets in screen-film (SF) images, computed radiographic (CR) images, and compressed CR images was measured using contrast detail (CD) analysis. The results of these studies were used to design a two- alternative forced-choice (2AFC) experiment to investigate the detectability of nodules in adult chest radiographs. CD curves for a common screen-film system were compared with CR images compressed up to 125:1. Data from clinical chest exams were used to define a CD region of clinical interest that sufficiently challenged the observer. From that data, simulated lesions were introduced into 100 normal CR chest films, and forced-choice observer performance studies were performed. CR images were compressed using a full-frame discrete cosine transform (FDCT) technique, where the 2D Fourier space was divided into four areas of different quantization depending on the cumulative power spectrum (energy) of each image. The characteristic curve of the CR images was adjusted so that optical densities matched those of the SF system. The CD curves for SF and uncompressed CR systems were statistically equivalent. The slope of the CD curve for each was - 1.0 as predicted by the Rose model. There was a significant degradation in detection found for CR images compressed to 125:1. Furthermore, contrast-detail analysis demonstrated that many pulmonary nodules encountered in clinical practice are significantly above the average observer threshold for detection. We designed a 2AFC observer study using simulated 1-cm lesions introduced into normal CR chest radiographs. Detectability was reduced for all compressed CR radiographs.

  18. Ventilation distribution and chest wall mechanics in microgravity

    NASA Technical Reports Server (NTRS)

    Paiva, M.; Wantier, M.; Verbanck, S.; Engel, L. A.; Prisk, G. K.; Guy, H. J. B.; West, J. B.

    1997-01-01

    The effect of gravity on lung ventilation distribution and the mechanisms of the chest wall were investigated. The following tests were performed with the respiratory monitoring system of the Anthorack, flown onboard Spacelab D2 mission: single breath washout (SBW), multiple breath washout (MBW) and argon rebreathing (ARB). In order to study chest wall mechanisms in microgravity, a respiratory inductive plethysmograph was used. The SBW tests did not reach statistical significance, while the ARB tests showed that gravity independent inhomogeneity of specific ventilation is larger than gravity dependent inhomogeneity. In which concerns the chest wall mechanisms, the analysis on the four astronauts during the normal respirations of the relaxation maneuver showed a 40 percent increase on the abdominal contribution to respiration.

  19. A randomized trial of continuous versus interrupted chest compressions in out-of-hospital cardiac arrest: rationale for and design of the Resuscitation Outcomes Consortium Continuous Chest Compressions Trial.

    PubMed

    Brown, Siobhan P; Wang, Henry; Aufderheide, Tom P; Vaillancourt, Christian; Schmicker, Robert H; Cheskes, Sheldon; Straight, Ron; Kudenchuk, Peter; Morrison, Laurie; Colella, M Riccardo; Condle, Joseph; Gamez, George; Hostler, David; Kayea, Tami; Ragsdale, Sally; Stephens, Shannon; Nichol, Graham

    2015-03-01

    The Resuscitation Outcomes Consortium is conducting a randomized trial comparing survival with hospital discharge after continuous chest compressions without interruption for ventilation versus currently recommended American Heart Association cardiopulmonary resuscitation with interrupted chest compressions in adult patients with out-of-hospital cardiac arrest without obvious trauma or respiratory cause. Emergency medical services perform study cardiopulmonary resuscitation for 3 intervals of manual chest compressions (each ~2 minutes) or until restoration of spontaneous circulation. Patients randomized to the continuous chest compression intervention receive 200 chest compressions with positive pressure ventilations at a rate of 10/min without interruption in compressions. Those randomized to the interrupted chest compression study arm receive chest compressions interrupted for positive pressure ventilations at a compression:ventilation ratio of 30:2. In either group, each interval of compressions is followed by rhythm analysis and defibrillation as required. Insertion of an advanced airway is deferred for the first ≥6 minutes to reduce interruptions in either study arm. The study uses a cluster randomized design with every-6-month crossovers. The primary outcome is survival to hospital discharge. Secondary outcomes are neurologically intact survival and adverse events. A maximum of 23,600 patients (11,800 per group) enrolled during the post-run-in phase of the study will provide ≥90% power to detect a relative change of 16% in the rate of survival to discharge, 8.1% to 9.4% with overall significance level of 0.05. If this trial demonstrates improved survival with either strategy, >3,000 premature deaths from cardiac arrest would be averted annually. PMID:25728722

  20. Impact of ventilation strategies during chest compression. An experimental study with clinical observations.

    PubMed

    Cordioli, Ricardo L; Lyazidi, Aissam; Rey, Nathalie; Granier, Jean-Max; Savary, Dominique; Brochard, Laurent; Richard, Jean-Christophe M

    2016-01-15

    The optimal ventilation strategy during cardiopulmonary resuscitation (CPR) is unknown. Chest compression (CC) generates circulation, while during decompression, thoracic recoil generates negative pressure and venous return. Continuous flow insufflation of oxygen (CFI) allows noninterrupted CC and generates positive airway pressure (Paw). The main objective of this study was to assess the effects of positive Paw compared with the current recommended ventilation strategy on intrathoracic pressure (P(IT)) variations, ventilation, and lung volume. In a mechanical model, allowing compression of the thorax below an equilibrium volume mimicking functional residual capacity (FRC), CC alone or with manual bag ventilation were compared with two levels of Paw with CFI. Lung volume change below FRC at the end of decompression and P(IT), as well as estimated alveolar ventilation, were measured during the bench study. Recordings were obtained in five cardiac arrest patients to confirm the bench findings. Lung volume was continuously below FRC, and as a consequence P(IT) remained negative during decompression in all situations, including with positive Paw. Compared with manual bag or CC alone, CFI with positive Paw limited the fall in lung volume and resulted in larger positive and negative P(IT) variations. Positive Paw with CFI significantly augmented ventilation induced by CC. Recordings in patients confirmed a major loss of lung volume below FRC during CPR, even with positive Paw. Compared with manual bag ventilation, positive Paw associated with CFI limits the loss in lung volume, enhances CC-induced positive P(IT), maintains negative P(IT) during decompression, and generates more alveolar ventilation. PMID:26586906

  1. Is It Possible to Maintain Consciousness and Spontaneous Ventilation with Chest Compression in the Early Phase of Cardiac Arrest?

    PubMed Central

    Oksar, Menekse; Turhanoglu, Selim

    2016-01-01

    Chest compression is important in cardiopulmonary resuscitation. However, life support algorithms do not specify when chest compression should be initiated in patients with persistent spontaneous normal breathing in the early phase after cardiac arrest. Here we describe the case of a 69-year-old man who underwent femoral bypass surgery and was extubated at the end of the procedure. After extubation, the patient's breathing pattern and respiratory rate were normal. The patient subsequently developed ventricular fibrillation, evident on two monitors. Because defibrillation was ineffective, chest compression was initiated even though the patient had spontaneous normal breathing and defensive motor reflexes, which were continued throughout resuscitation. He regained consciousness and underwent tracheal extubation without neurological sequelae on postoperative day 1. This case highlights the necessity of chest compression in the early phase of cardiac arrest. PMID:26981288

  2. Chest compression-only CPR or good quality 30:2 CPR.

    PubMed

    Anantharaman, V

    2011-08-01

    There is debate as to whether chest compression-only cardiopulmonary resuscitation (CC-CPR) or standard 30:2 CPR should be taught to laypersons. Equivalence in outcomes between standard CPR and CC-CPR has been amply demonstrated in communities with short ambulance response times of about five minutes. Depriving oxygen from a collapsed patient beyond six minutes results in poorer outcomes. Communities with prolonged ambulance travel times have seen improved outcomes with CPR than CC-CPR. While healthcare workers demonstrate a reluctance to perform mouth-to-mouth ventilation, laypersons generally show a willingness to do so. Rescuer fatigue also argues against the use of CC-CPR for more than a few minutes. For communities with relatively long ambulance transport times, the best approach appears to be standard CPR, with emphasis on good quality compression. For dispatcher-assisted CPR, communication issues suggest that CC-CPR is advisable. Public CPR training should include teaching of mouth-to-mouth ventilation alternating with chest compressions. PMID:21879215

  3. A New Chest Compression Depth Feedback Algorithm for High-Quality CPR Based on Smartphone

    PubMed Central

    Song, Yeongtak; Oh, Jaehoon

    2015-01-01

    Abstract Background Although many smartphone application (app) programs provide education and guidance for basic life support, they do not commonly provide feedback on the chest compression depth (CCD) and rate. The validation of its accuracy has not been reported to date. This study was a feasibility assessment of use of the smartphone as a CCD feedback device. In this study, we proposed the concept of a new real-time CCD estimation algorithm using a smartphone and evaluated the accuracy of the algorithm. Materials and Methods Using the double integration of the acceleration signal, which was obtained from the accelerometer in the smartphone, we estimated the CCD in real time. Based on its periodicity, we removed the bias error from the accelerometer. To evaluate this instrument's accuracy, we used a potentiometer as the reference depth measurement. The evaluation experiments included three levels of CCD (insufficient, adequate, and excessive) and four types of grasping orientations with various compression directions. We used the difference between the reference measurement and the estimated depth as the error. The error was calculated for each compression. Results When chest compressions were performed with adequate depth for the patient who was lying on a flat floor, the mean (standard deviation) of the errors was 1.43 (1.00) mm. When the patient was lying on an oblique floor, the mean (standard deviation) of the errors was 3.13 (1.88) mm. Conclusions The error of the CCD estimation was tolerable for the algorithm to be used in the smartphone-based CCD feedback app to compress more than 51 mm, which is the 2010 American Heart Association guideline. PMID:25402865

  4. Optimizing ventilation in conjunction with phased chest and abdominal compression-decompression (Lifestick) resuscitation.

    PubMed

    Kern, Karl B; Hilwig, Ronald W; Berg, Robert A; Schock, Robert B; Ewy, Gordon A

    2002-01-01

    The best method for employment of phased chest and abdominal compression-decompression (Lifestick) cardiopulmonary resuscitation (CPR) has yet to be determined. Of particular concern with using this technique is the combining of ventilation with the phased compressions and decompressions. Twenty domestic swine (50+/-1 kg) were equally divided into four groups. Following 10 min of untreated VF, CPR was begun. Group 1 received Lifestick (LS) CPR with only passive ventilation ('passive'); Group 2 received LS-CPR with synchronized positive pressure ventilations (ppv) at a chest compression ratio of 15:2 (15:2 S); Group 3 had LS-CPR with synchronized ppv at 5:1 (5:1 S); and Group 4 received LS-CPR with asynchronous ppv at 5:1 (5:1 A). Endpoints included hemodynamics, blood gases, minute ventilation, and 24 h outcome. Asynchronous ventilation (5:1 A) had significantly worse hemodynamics including aortic and right atrial systolic, aortic diastolic, and coronary perfusion pressures than the other groups (P<0.05). Passive ventilation had the poorest arterial and mixed venous blood gases (P<0.05), but did not differ from 15:2 S in minute ventilation produced (8 vs 10 l/min). No differences in outcome were seen. The ventilation technique combined with LS-CPR can make a significant difference in hemodynamics as well as ventilation. Optimizing other forms of basic and advanced cardiac life support through different ventilation methods deserves new consideration, including a re-examination of the current single rescuer recommendation of a 15:2 ratio. Optimal ventilation strategy when using the LS device at 60 compressions per min appears to be 5:1 S. Such data is important for conducting clinical trials with this new CPR adjunct. PMID:11801354

  5. Measurement and control for mechanical compressive stress

    NASA Astrophysics Data System (ADS)

    Li, Qing; Ye, Guang; Pan, Lan; Wu, Xiushan

    2001-12-01

    At present, the indirect method is applied to measuring and controlling mechanical compressive stress, which is the measurement and control of rotating torque of screw with torque transducer during screw revolving. Because the friction coefficient between every screw-cap and washer, of screw-thread is different, the compressive stress of every screw may is different when the machinery is equipped. Therefore, the accurate measurement and control of mechanical compressive stress is realized by the direct measurement of mechanical compressive stress. The author introduces the research of contrast between compressive stress and rotating torque in the paper. The structure and work principle of a special washer type transducer is discussed emphatically. The special instrument cooperates with the washer type transducer for measuring and controlling mechanical compressive stress. The control tactics based on the rate of compressive stress is put to realize accurate control of mechanical compressive stress.

  6. Impact of the 2010 resuscitation guidelines training on layperson chest compressions

    PubMed Central

    Blewer, Audrey L.; Buckler, David G.; Li, Jiaqi; Leary, Marion; Becker, Lance B.; Shea, Judy A.; Groeneveld, Peter W.; Putt, Mary E.; Abella, Benjamin S.

    2015-01-01

    BACKGROUND: Survival from cardiac arrest is sensitive to the quality of delivered CPR. In 2010, updated international resuscitation guidelines emphasized deeper chest compressions and faster rates, yet it is unknown whether training laypersons using updated guidelines resulted in changed CPR performance. We hypothesized that laypersons taught CPR using the 2010 guidelines performed deeper and faster compressions than those taught using the 2005 materials. METHODS: This work represents a secondary analysis of a study conducted at eight hospitals where family members of hospitalized cardiac patients were trained in CPR. An initial cohort was trained using the 2005 guidelines, and a subsequent cohort was trained using the 2010 guideline materials. Post training, CPR skills were quantified using a recording manikin. RESULTS: Between May 2009 to August 2013, 338 subjects completed the assessment. Among the subjects, 176 received 2005 training and 162 underwent 2010 training. The mean compression rate in the 2005 cohort was 87 (95%CI 83–90) per minute, and in the 2010 cohort was 86 (95%CI 83–90) per minute (P=ns), while the mean compression depth was 34 (95%CI 32–35) mm in the 2005 cohort and 46 (95%CI 44–47) mm in the 2010 cohort (P<0.01). CONCLUSIONS: Training with the 2010 CPR guidelines resulted in a statistically significant increase in trainees’ compression depth but there was no change in compression rate. Nevertheless, the majority of CPR performed by trainees in both cohorts was below the guideline recommendation, highlighting an important gap between training goals and trainee performance. PMID:26693261

  7. Minute ventilation at different compression to ventilation ratios, different ventilation rates, and continuous chest compressions with asynchronous ventilation in a newborn manikin

    PubMed Central

    2012-01-01

    Background In newborn resuscitation the recommended rate of chest compressions should be 90 per minute and 30 ventilations should be delivered each minute, aiming at achieving a total of 120 events per minute. However, this recommendation is based on physiological plausibility and consensus rather than scientific evidence. With focus on minute ventilation (Mv), we aimed to compare today’s standard to alternative chest compression to ventilation (C:V) ratios and different ventilation rates, as well as to continuous chest compressions with asynchronous ventilation. Methods Two investigators performed cardiopulmonary resuscitation on a newborn manikin with a T-piece resuscitator and manual chest compressions. The C:V ratios 3:1, 9:3 and 15:2, as well as continuous chest compressions with asynchronous ventilation (120 compressions and 40 ventilations per minute) were performed in a randomised fashion in series of 10 × 2 minutes. In addition, ventilation only was performed at three different rates (40, 60 and 120 ventilations per minute, respectively). A respiratory function monitor measured inspiration time, tidal volume and ventilation rate. Mv was calculated for the different interventions and the Mann–Whitney test was used for comparisons between groups. Results Median Mv per kg in ml (interquartile range) was significantly lower at the C:V ratios of 9:3 (140 (134–144)) and 15:2 (77 (74–83)) as compared to 3:1 (191(183–199)). With ventilation only, there was a correlation between ventilation rate and Mv despite a negative correlation between ventilation rate and tidal volumes. Continuous chest compressions with asynchronous ventilation gave higher Mv as compared to coordinated compressions and ventilations at a C:V ratio of 3:1. Conclusions In this study, higher C:V ratios than 3:1 compromised ventilation dynamics in a newborn manikin. However, higher ventilation rates, as well as continuous chest compressions with asynchronous ventilation gave higher Mv

  8. Four-stage teaching technique and chest compression performance of medical students compared to conventional technique

    PubMed Central

    Jenko, Matej; Frangež, Maja; Manohin, Aleksander

    2012-01-01

    Aim To compare the 2-stage and 4-stage basic life support teaching technique. The second aim was to test if students’ self-evaluated knowledge was in accordance with their actual knowledge. Methods A total of 126 first-year students of the Faculty of Medicine in Ljubljana were involved in this parallel study conducted in the academic year 2009/2010. They were divided into ten groups. Five groups were taught the 2-stage model and five the 4-stage model. The students were tested in a scenario immediately after the course. Questionnaires were filled in before and after the course. We assessed the absolute values of the chest compression variables and the proportions of students whose performance was evaluated as correct according to our criteria. The results were analyzed with independent samples t test or Mann-Whitney-U test. Proportions were compared with χ2 test. The correlation was calculated with the Pearson coefficient. Results There was no difference between the 2-stage (2S) and the 4-stage approach (4S) in the compression rate (126 ± 13 min-1 vs 124 ± 16 min -1, P = 0.180, independent samples t test), compression depth (43 ± 7 mm vs 44 ± 8 mm, P = 0.368, independent samples t test), and the number of compressions with correct hand placement (79 ± 32% vs 78 ± 12, P = 0.765, Mann-Whitney U-test). However, students from the 4-stage group had a significantly higher average number of compressions per minute (70 ± 13 min -1 2S, 78 ± 12 min-1 4S, P = 0.02, independent samples t test). The percentage of students with all the variables correct was the same (13% 2S, 15% 4S, P = 0.741, χ2 test). There was no correlation between the students’ actual and self-evaluated knowledge (P = 0.158, Pearson coefficient = 0.127). Conclusions The 4-stage teaching technique does not significantly improve the quality of chest compressions. The students’ self-evaluation of their performance after the course was

  9. Evaluation of chest injury mechanisms in nearside oblique frontal impacts.

    PubMed

    Iraeus, Johan; Lindquist, Mats; Wistrand, Sofie; Sibgård, Elin; Pipkorn, Bengt

    2013-01-01

    Despite the use of seat belts and modern safety systems, many automobile occupants are still seriously injured or killed in car crashes. Common configurations in these crashes are oblique and small overlap frontal impacts that often lead to chest injuries.To evaluate the injury mechanism in these oblique impacts, an investigation was carried out using mathematical human body model simulations. A model of a simplified vehicle interior was developed and validated by means of mechanical sled tests with the Hybrid III dummy. The interior model was then combined with the human body model THUMS and validated by means of mechanical PMHS sled tests. Occupant kinematics as well as rib fracture patterns were predicted with reasonable accuracy.The final model was updated to conform to modern cars and a simulation matrix was run. In this matrix the boundary conditions, ΔV and PDOF, were varied and rib fracture risk as a function of the boundary conditions was evaluated using a statistical framework.In oblique frontal impacts, two injury producing mechanisms were found; (i) diagonal belt load and (ii) side structure impact. The second injury mechanism was found for PDOFs of 25°-35°, depending on ΔV. This means that for larger PDOFs, less ΔV is needed to cause a serious chest injury. PMID:24406957

  10. Evaluation of Chest Injury Mechanisms in Nearside Oblique Frontal Impacts

    PubMed Central

    Iraeus, Johan; Lindquist, Mats; Wistrand, Sofie; Sibgård, Elin; Pipkorn, Bengt

    2013-01-01

    Despite the use of seat belts and modern safety systems, many automobile occupants are still seriously injured or killed in car crashes. Common configurations in these crashes are oblique and small overlap frontal impacts that often lead to chest injuries. To evaluate the injury mechanism in these oblique impacts, an investigation was carried out using mathematical human body model simulations. A model of a simplified vehicle interior was developed and validated by means of mechanical sled tests with the Hybrid III dummy. The interior model was then combined with the human body model THUMS and validated by means of mechanical PMHS sled tests. Occupant kinematics as well as rib fracture patterns were predicted with reasonable accuracy. The final model was updated to conform to modern cars and a simulation matrix was run. In this matrix the boundary conditions, ΔV and PDOF, were varied and rib fracture risk as a function of the boundary conditions was evaluated using a statistical framework. In oblique frontal impacts, two injury producing mechanisms were found; (i) diagonal belt load and (ii) side structure impact. The second injury mechanism was found for PDOFs of 25°–35°, depending on ΔV. This means that for larger PDOFs, less ΔV is needed to cause a serious chest injury. PMID:24406957

  11. Comparison of the McGrath MAC video laryngoscope and the Pentax Airwayscope during chest compression: a manikin study.

    PubMed

    Kotera, Atsushi; Irie, Hiroki; Iwashita, Shinsuke; Taniguchi, Junichi; Kasaoka, Shunji; Kinoshita, Yoshihiro

    2014-01-01

    We tested the utility of the McGrath MAC(®) (McG) video laryngoscope during chest compression compared with the Pentax Airwayscope(®) (AWS). We recruited 59 participants into the simulation study. The difference in the time to intubation (TTI [sec]) between without and with chest compression was significant for the AWS attempts (median 13, range 6-28 vs. median 15, range 6-72, p = 0.0247) but not significant for the McG attempts (median 16, range 6-75 vs. median 16, range 6-71); however, the difference of the TTIs is not serious clinically. The utility of the two devices during chest compressions is almost similar although their characteristics are different. PMID:25520833

  12. Comparison of Methods for the Determination of Cardiopulmonary Resuscitation Chest Compression Fraction

    PubMed Central

    Iyanaga, Masayuki; Gray, Randal; Stephens, Shannon W.; Akinsanya, Olajide; Rodgers, Joel; Smyrski, Kathleen; Wang, Henry E.

    2012-01-01

    Objective While cardiopulmonary resuscitation (CPR) chest compression fraction (CCF) is associated with out-of-hospital cardiac arrest (OHCA) outcomes, there is no standard method for the determination of CCF. We compared nine methods for calculating CCF. Methods We studied consecutive adult OHCA patients treated by Alabama Emergency Medical Services (EMS) agencies of the Resuscitation Outcomes Consortium (ROC) during Jan. 1, 2010 - Oct. 28, 2010. Paramedics used portable cardiac monitors with real-time chest compression detection technology (LifePak 12, Physio-Control, Redmond, Washington). We performed both automated CCF calculation for the entire care episode as well as manual review of CPR data in 1-minute epochs, defining CCF as the proportion of each treatment interval with active chest compressions. We compared the CCF values resulting from 9 calculation methods: 1) mean CCF for the entire patient care episode (automated calculation by manufacturer software), 2) mean CCF for first 3 minutes of patient care, 3) mean CCF for first 5 minutes, 4) mean CCF for first 10 minutes, 5) mean CCF for the entire episode except first 5 minutes, 6) mean CCF for last 5 minutes, 7) mean CCF from start to first shock, 8) mean CCF for the first half of resuscitation, 9) mean CCF for the second half of resuscitation. We compared CCF for Methods 2-9 with Method 1 using paired t-tests with a Bonferroni-adjusted p-value of 0.006 (99.5% confidence intervals). Results Among 102 adult OHCA, patient demographics were: mean age 60.3 years (SD 20.8 years), African American 56.9%, male 63.7%, and shockable ECG rhythm 23.5%. Mean CPR duration was 728 seconds (95% CI: 647-809 seconds). Mean CCF for the 9 CCF calculation methods were: 1) 0.587; 2) 0.526; 3) 0.541; 4) 0.566; 5) 0.562; 6) 0.597; 7) 0.530; 8) 0.550; 9) 0.590%. Compared with Method 1, Method 7 CCF (start to first shock) was slightly lower (−0.057; 99.5% CI: −0.100 – (−0.014)). There were no other statistically

  13. Eccentric crank variable compression ratio mechanism

    DOEpatents

    Lawrence, Keith Edward; Moser, William Elliott; Roozenboom, Stephan Donald; Knox, Kevin Jay

    2008-05-13

    A variable compression ratio mechanism for an internal combustion engine that has an engine block and a crankshaft is disclosed. The variable compression ratio mechanism has a plurality of eccentric disks configured to support the crankshaft. Each of the plurality of eccentric disks has at least one cylindrical portion annularly surrounded by the engine block. The variable compression ratio mechanism also has at least one actuator configured to rotate the plurality of eccentric disks.

  14. Chest Compression With Personal Protective Equipment During Cardiopulmonary Resuscitation: A Randomized Crossover Simulation Study.

    PubMed

    Chen, Jie; Lu, Kai-Zhi; Yi, Bin; Chen, Yan

    2016-04-01

    Following a chemical, biological, radiation, and nuclear incident, prompt cardiopulmonary resuscitation (CPR) procedure is essential for patients who suffer cardiac arrest. But CPR when wearing personal protection equipment (PPE) before decontamination becomes a challenge for healthcare workers (HCW). Although previous studies have assessed the impact of PPE on airway management, there is little research available regarding the quality of chest compression (CC) when wearing PPE.A present randomized cross-over simulation study was designed to evaluate the effect of PPE on CC performance using mannequins.The study was set in one university medical center in the China.Forty anesthesia residents participated in this randomized cross-over study.Each participant performed 2 min of CC on a manikin with and without PPE, respectively. Participants were randomized into 2 groups that either performed CC with PPE first, followed by a trial without PPE after a 180-min rest, or vice versa.CPR recording technology was used to objectively quantify the quality of CC. Additionally, participants' physiological parameters and subjective fatigue score values were recorded.With the use of PPE, a significant decrease of the percentage of effective compressions (41.3 ± 17.1% with PPE vs 67.5 ± 15.6% without PPE, P < 0.001) and the percentage of adequate compressions (67.7 ± 18.9% with PPE vs 80.7 ± 15.5% without PPE, P < 0.001) were observed. Furthermore, the increases in heart rate, mean arterial pressure, and subjective fatigue score values were more obvious with the use of PPE (all P < 0.01).We found significant deterioration of CC performance in HCW with the use of a level-C PPE, which may be a disadvantage for enhancing survival of cardiac arrest. PMID:27057878

  15. Three cases of suprachoroidal hemorrhage associated with chest compression or asphyxiation and detected using postmortem computed tomography.

    PubMed

    Oshima, Toru; Yoshikawa, Hiroshi; Ohtani, Maki; Mimasaka, Sohtaro

    2015-05-01

    We report 3 cases of suprachoroidal hemorrhage (SCH) found to be triggered by increased intrathoracic pressure and detected using postmortem computed tomography (PMCT). Case 1 was a man aged in his 50s who was found dead at a landslide site. The autopsy showed clogging of the upper respiratory tract with soil debris from the landslide. The cause of death was determined to be asphyxia. PMCT showed SCH in both eyes, which was believed to be caused by chest compression or choking on the soil debris from the landslide. Case 2 was a woman aged in her 60s who was found dead in the sea. The autopsy revealed injuries primarily to her chest. We concluded that the cause of death was drowning. PMCT showed SCH in her right eye that was believed to be caused by chest compression. Case 3 was a woman aged in her 80s who was buried in a snowdrift and potentially died from hypothermia. PMCT showed SCH in both eyes, which was considered to be from an increase in intrathoracic pressure that might have been caused by the burial in the snow. Histological findings showed serous retinal detachment associated with retinal pigment epithelium damage due to SCH, which indicated that she was alive for several hours after the onset of SCH. The increase in intrathoracic pressure caused by dyspnea or chest compression was considered responsible for the onset of SCH in all of the present cases. PMCT might assist with the differential diagnosis of traumatic asphyxiation by SCH. PMID:25533924

  16. Effects of chest wall compression on expiratory flow rates in patients with chronic obstructive pulmonary disease

    PubMed Central

    Nozoe, Masafumi; Mase, Kyoshi; Ogino, Tomoyuki; Murakami, Shigefumi; Takashima, Sachie; Domen, Kazuhisa

    2016-01-01

    Background: Manual chest wall compression (CWC) during expiration is a technique for removing airway secretions in patients with respiratory disorders. However, there have been no reports about the physiological effects of CWC in patients with chronic obstructive pulmonary disease (COPD). Objective: To compare the effects of CWC on expiratory flow rates in patients with COPD and asymptomatic controls. Method: Fourteen subjects were recruited from among patients with COPD who were receiving pulmonary rehabilitation at the University Hospital (COPD group). Fourteen age-matched healthy subjects were also consecutively recruited from the local community (Healthy control group). Airflow and lung volume changes were measured continuously with the subjects lying in supine position during 1 minute of quiet breathing (QB) and during 1 minute of CWC by a physical therapist. Results: During CWC, both the COPD group and the healthy control group showed significantly higher peak expiratory flow rates (PEFRs) than during QB (mean difference for COPD group 0.14 L/sec, 95% confidence interval (CI) 0.04 to 0.24, p<0.01, mean difference for healthy control group 0.39 L/sec, 95% CI 0.25 to 0.57, p<0.01). In the between-group comparisons, PEFR was significantly higher in the healthy control group than in the COPD group (-0.25 L/sec, 95% CI -0.43 to -0.07, p<0.01). However, the expiratory flow rates at the lung volume at the PEFR during QB and at 50% and 25% of tidal volume during QB increased in the healthy control group (mean difference for healthy control group 0.31 L/sec, 95% CI 0.15 to 0.47, p<0.01: 0.31 L/sec, 95% CI 0.15 to 0.47, p<0.01: 0.27 L/sec, 95% CI 0.13 to 0.41, p<0.01, respectively) but not in the COPD group (0.05 L/sec, 95% CI -0.01 to 0.12: -0.01 L/sec, 95% CI -0.11 to 0.08: 0.02 L/sec, 95% CI -0.05 to 0.90) with the application of CWC. Conclusion: The effects of chest wall compression on expiratory flow rates was different between COPD patients and asymptomatic

  17. Virtual arterial blood pressure feedback improves chest compression quality during simulated resuscitation☆

    PubMed Central

    Rieke, Horst; Rieke, Martin; Gado, Samkon K.; Nietert, Paul J.; Field, Larry C.; Clark, Carlee A.; Furse, Cory M.; McEvoy, Matthew D.

    2014-01-01

    Introduction Quality chest compressions (CC) are the most important factor in successful cardiopulmonary resuscitation. Adjustment of CC based upon an invasive arterial blood pressure (ABP) display would be theoretically beneficial. Additionally, having one compressor present for longer than a 2-min cycle with an ABP display may allow for a learning process to further maximize CC. Accordingly, we tested the hypothesis that CC can be improved with a real-time display of invasively measured blood pressure and with an unchanged, physically fit compressor. Methods A manikin was attached to an ABP display derived from a hemodynamic model responding to parameters of CC rate, depth, and compression-decompression ratio. The area under the blood pressure curve over time (AUC) was used for data analysis. Each participant (N = 20) performed 4 CPR sessions: (1) No ABP display, exchange of compressor every 2 min; (2) ABP display, exchange of compressor every 2 min; (3) no ABP display, no exchange of the compressor; (4) ABP display, no exchange of the compressor. Data were analyzed by ANOVA. Significance was set at a p-value < 0.05. Results The average AUC for cycles without ABP display was 5201 mmHg s (95% confidence interval (CI) of 4804–5597 mmHg s), and for cycles with ABP display 6110 mmHg s (95% CI of 5715–6507 mmHg s) (p< 0.0001). The average AUC increase with ABP display for each participant was 20.2 ± 17.4% 95 CI (p < 0.0001). Conclusions Our study confirms the hypothesis that a real-time display of simulated ABP during CPR that responds to participant performance improves achieved and sustained ABP. However, without any real-time visual feedback, even fit compressors demonstrated degradation of CC quality. PMID:23816900

  18. Using an inertial navigation algorithm and accelerometer to monitor chest compression depth during cardiopulmonary resuscitation.

    PubMed

    Boussen, Salah; Ibouanga-Kipoutou, Harold; Fournier, Nathalie; Raboutet, Yves Godio; Llari, Maxime; Bruder, Nicolas; Arnoux, Pierre Jean; Behr, Michel

    2016-09-01

    We present an original method using a low cost accelerometer and a Kalman-filter based algorithm to monitor cardiopulmonary resuscitation chest compressions (CC) depth. A three-axis accelerometer connected to a computer was used during CC. A Kalman filter was used to retrieve speed and position from acceleration data. We first tested the algorithm for its accuracy and stability on surrogate data. The device was implemented for CC performed on a manikin. Different accelerometer locations were tested. We used a classical inertial navigation algorithm to reconstruct CPR depth and frequency. The device was found accurate enough to monitor CPR depth and its stability was checked for half an hour without any drift. Average error on displacement was ±0.5mm. We showed that depth measurement was dependent on the device location on the patient or the rescuer. The accuracy and stability of this small low-cost accelerometer coupled to a Kalman-filter based algorithm to reconstruct CC depth and frequency, was found well adapted and could be easily implemented. PMID:27246666

  19. Pulse Oximetry: A Non-Invasive, Novel Marker for the Quality of Chest Compressions in Porcine Models of Cardiac Arrest

    PubMed Central

    Han, Fei; Li, Yan; Walline, Joseph; Fu, Yangyang; Yao, Dongqi; Zhang, Xiaocui; Zhang, Hui; Zhu, Huadong; Guo, Shubin; Wang, Zhong; Yu, Xuezhong

    2015-01-01

    Objective Pulse oximetry, which noninvasively detects the blood flow of peripheral tissue, has achieved widespread clinical use. We have noticed that the better the quality of cardiopulmonary resuscitation (CPR), the better the appearance of pulse oximetry plethysmographic waveform (POP). We investigated whether the area under the curve (AUC) and/or the amplitude (Amp) of POP could be used to monitor the quality of CPR. Design Prospective, randomized controlled study. Setting Animal experimental center in Peking Union Medical Collage Hospital, Beijing, China. Subjects Healthy 3-month-old male domestic swine. Interventions 34 local pigs were enrolled in this study. After 4 minutes of untreated ventricular fibrillation, animals were randomly assigned into two resuscitation groups: a “low quality” group (with a compression depth of 3cm) and a “high quality” group (with a depth of 5cm). All treatments between the two groups were identical except for the depth of chest compressions. Hemodynamic parameters [coronary perfusion pressure (CPP), partial pressure of end-tidal carbon dioxide (PETCO2)] as well as AUC and Amp of POP were all collected and analyzed. Measurements and Findings There were statistical differences between the “high quality” group and the “low quality” group in AUC, Amp, CPP and PETCO2 during CPR (P<0.05). AUC, Amp and CPP were positively correlated with PETCO2, respectively (P<0.01). There was no statistical difference between the heart rate calculated according to the POP (FCPR) and the frequency of mechanical CPR at the 3rd minute of CPR. The FCPR was lower than the frequency of mechanical CPR at the 6th and the 9th minute of CPR. Conclusions Both the AUC and Amp of POP correlated well with CPP and PETCO2 in animal models. The frequency of POP closely matched the CPR heart rate. AUC and Amp of POP might be potential noninvasive quality monitoring markers for CPR. PMID:26485651

  20. Peyton's 4-Steps-Approach in comparison: Medium-term effects on learning external chest compression – a pilot study

    PubMed Central

    Münster, Tobias; Stosch, Christoph; Hindrichs, Nina; Franklin, Jeremy; Matthes, Jan

    2016-01-01

    Introduction: The external chest compression is a very important skill required to maintain a minimum of circulation during cardiac arrest until further medical procedures can be taken. Peyton’s 4-Steps-Approach is one method of skill training, the four steps being: Demonstration, Deconstruction, Comprehension and Execution. Based on CPR skill training, this method is widely, allegedly predominantly used, although there are insufficient studies on Peyton’s 4-Steps-Approach for skill training in CPR in comparison with other methods of skill training. In our study, we compared the medium- term effects on learning external chest compression with a CPR training device in three different groups: PEY (Peyton’s 4-Steps-Approach), PMOD (Peyton’s 4-Steps-Approach without Step 3) and STDM, the standard model, according to the widely spread method “see one, do one” (this is equal to Peyton’s step 1 and 3). Material and Methods: This prospective and randomised pilot study took place during the summer semester of 2009 at the SkillsLab and Simulation Centre of the University of Cologne (Kölner interprofessionelles Skills Lab und Simulationszentrum - KISS). The subjects were medical students (2nd and 3rd semester). They volunteered for the study and were randomised in three parallel groups, each receiving one of the teaching methods mentioned above. One week and 5/6 months after the intervention, an objective, structured single assessment was taken. Compression rate, compression depth, correct compressions, and the sum of correct checklist items were recorded. Additionally, we compared cumulative percentages between the groups based on the correct implementation of the resuscitation guidelines during that time. Results: The examined sample consisted of 134 subjects (68% female; age 22±4; PEY: n=62; PMOD: n=31; STDM: n=41). There was no difference between the groups concerning age, gender, pre-existing experience in CPR or time of last CPR course. The only

  1. Instructions to “push as hard as you can” improve average chest compression depth in dispatcher-assisted Cardiopulmonary Resuscitation

    PubMed Central

    Mirza, Muzna; Brown, Todd B.; Saini, Devashish; Pepper, Tracy L; Nandigam, Hari Krishna; Kaza, Niroop; Cofield, Stacey S.

    2008-01-01

    Background and Objective Cardiopulmonary Resuscitation (CPR) with adequate chest compression depth appears to improve first shock success in cardiac arrest. We evaluate the effect of simplification of chest compression instructions on compression depth in dispatcher-assisted CPR protocol. Methods Data from two randomized, double-blinded, controlled trials with identical methodology were combined to obtain 332 records for this analysis. Subjects were randomized to either modified Medical Priority Dispatch System (MPDS) v11.2 protocol or a new simplified protocol. The main difference between the protocols was the instruction to “push as hard as you can” in the simplified protocol, compared to “push down firmly 2 inches (5cm)” in MPDS. Data were recorded via a Laerdal® ResusciAnne® SkillReporter™ manikin. Primary outcome measures included: chest compression depth, proportion of compressions without error, with adequate depth and with total release. Results Instructions to “push as hard as you can”, compared to “push down firmly 2 inches (5cm)”, resulted in improved chest compression depth (36.4 vs 29.7 mm, p<0.0001), and improved median proportion of chest compressions done to the correct depth (32% vs <1%, p<0.0001). No significant difference in median proportion of compressions with total release (100% for both) and average compression rate (99.7 vs 97.5 per min, p<0.56) was found. Conclusions Modifying dispatcher-assisted CPR instructions by changing “push down firmly 2 inches (5cm)” to “push as hard as you can” achieved improvement in chest compression depth at no cost to total release or average chest compression rate. PMID:18635306

  2. Pitfalls with the "chest compression-only" approach: the challenge of an unusual cause.

    PubMed

    Reid, Bjørn Ole; Skogvoll, Eirik

    2010-01-01

    Chest compression-only (CC-only) is now incorporated in the Norwegian protocol for dispatch guided CPR (cardiopulmonary resuscitation) in cardiac arrest of presumed cardiac aetiology.We present a case that is unique and instructive as well as unusual. It reminds us of the challenges that face bystanders, dispatch centres and ambulance services when faced with possible cardiac arrest.This case report describes a 50 year old man in a rural community. He had suffered a heart attack 8 months previously, and was found unconscious with respiratory arrest in his garden one morning. Due to the proximity to the ambulance station, the paramedics were on the scene within three minutes. A chain-saw was lying beside him, but no external injuries were seen. The patient had no radial pulse, central cyanosis and respiratory gasps approximately every 30 seconds. Ventilation with bag and mask was given, and soon a femoral pulse could be palpated. Blood sugar was elevated and ECG (electrocardiogram) was normal. GCS (Glasgow Coma Scale) was 3. Upon arrival of the physician staffed air ambulance, further examination revealed bilateral miosis of the pupils and continuing bradypnoea. Naloxone was given with an immediate effect and the patient woke up. The patient denied intake of narcotics, but additional information from the dispatch centre revealed that he was hepatitis C positive. After a few hours, the patient admitted to have obtained a fentanyl transdermal patch from an acquaintance, having chewed it before falling unconscious. This case report shows the importance as well as the challenges of identifying a non-cardiac cause of possible cardiac arrest, and the value of providing causal therapy. PMID:20707888

  3. Ventilation by high-frequency chest wall compression in dogs with normal lungs.

    PubMed

    Zidulka, A; Gross, D; Minami, H; Vartian, V; Chang, H K

    1983-06-01

    In 6 anesthetized and paralyzed supine dogs, ventilation by high-frequency chest wall compression (HFCWC) was accomplished by a piston pump rapidly oscillating the pressure in a modified double blood pressure cuff wrapped around the lower thorax. Testing applied frequencies at 3, 5, 8, and 11 Hz, applied peak cuff pressures ranged from 30 to 230 cmH2O. This produced swings of esophageal pressure as high as 18 cmH2O and peak oscillatory air flow ranging from 0.7 to 1.6 L/s. Oscillatory tidal volume declined with increasing frequency and ranged from a mean of 61 to 45 ml. After 30 min of applied HFCWC, arterial blood gas determinations revealed a mean PaCO2 of 29.3 mmHg at 5 Hz, 35 mmHg at 3 Hz, 36 mmHg at 8 Hz, and 51 mmHg at 11 Hz. Mean PaO2 improved from ventilator control values at 3 Hz, remained unchanged at 5 and 8 Hz, and declined at 11 Hz. In 2 dogs breathing spontaneously, HFCWC applied at 5 and 11 Hz resulted in a reduction in spontaneous minute ventilation, mainly by a reduction in spontaneous tidal volume, whereas arterial blood gas values changed slightly. One dog ceased to breath spontaneously within 5 min of application of HFCWC as the PaCO2 fell below control values. We conclude that in dogs with normal lungs, HFCWC may assist spontaneous ventilation. In paralyzed dogs, HFCWC may be of sufficient magnitude to cause hyperventilation. PMID:6407373

  4. Mechanically induced sudden death in chest wall impact (commotio cordis).

    PubMed

    Link, Mark S

    2003-01-01

    Sudden death due to nonpenetrating chest wall impact in the absence of injury to the ribs, sternum and heart is known as commotio cordis. Although once thought rare, an increasing number of these events have been reported. Indeed, a significant percentage of deaths on the athletic field are due to chest wall impact. Commotio cordis is most frequently observed in young individuals (age 4-18 years), but may also occur in adults. Sudden death is instantaneous or preceded by several seconds of lightheadedness after the chest wall blow. Victims are most often found in ventricular fibrillation, and successful resuscitation is more difficult than expected given the young age, excellent health of the victims, and the absence of structural heart disease. Autopsy examination is notable for the lack of any significant cardiac or thoracic abnormalities. In an experimental model of commotio cordis utilizing anesthetized juvenile swine, ventricular fibrillation can be produced by a 30 mph baseball strike if the strike occurred during the vulnerable period of repolarization, on the upslope of the T-wave. Energy of the impact object was also found to be a critical variable with 40 mph baseballs more likely to cause ventricular fibrillation than velocities less or greater than 40 mph. In addition, more rigid impact objects and blows directly over the center of the chest were more likely to cause ventricular fibrillation. Peak left ventricular pressure generated by the chest wall blow correlated with the risk of ventricular fibrillation. Activation of the K(+)(ATP) channel is a likely cause of the ventricular fibrillation produced by chest wall blows. Successful resuscitation is attainable with early defibrillation. PMID:12732277

  5. Prehospital randomised assessment of a mechanical compression device in cardiac arrest (PaRAMeDIC) trial protocol

    PubMed Central

    2010-01-01

    Background Survival after out-of-hospital cardiac arrest is closely linked to the quality of CPR, but in real life, resuscitation during prehospital care and ambulance transport is often suboptimal. Mechanical chest compression devices deliver consistent chest compressions, are not prone to fatigue and could potentially overcome some of the limitations of manual chest compression. However, there is no high-quality evidence that they improve clinical outcomes, or that they are cost effective. The Prehospital Randomised Assessment of a Mechanical Compression Device In Cardiac Arrest (PARAMEDIC) trial is a pragmatic cluster randomised study of the LUCAS-2 device in adult patients with non-traumatic out-of-hospital cardiac arrest. Methods/design The primary objective of this trial is to evaluate the effect of chest compression using LUCAS-2 on mortality at 30 days post out-of-hospital cardiac arrest, compared with manual chest compression. Secondary objectives of the study are to evaluate the effects of LUCAS-2 on survival to 12 months, cognitive and quality of life outcomes and cost-effectiveness. Methods: Ambulance service vehicles will be randomised to either manual compression (control) or LUCAS arms. Adult patients in out-of-hospital cardiac arrest, attended by a trial vehicle will be eligible for inclusion. Patients with traumatic cardiac arrest or who are pregnant will be excluded. The trial will recruit approximately 4000 patients from England, Wales and Scotland. A waiver of initial consent has been approved by the Research Ethics Committees. Consent will be sought from survivors for participation in the follow-up phase. Conclusion The trial will assess the clinical and cost effectiveness of the LUCAS-2 mechanical chest compression device. Trial Registration: The trial is registered on the International Standard Randomised Controlled Trial Number Registry (ISRCTN08233942). PMID:21054860

  6. Competing hydrostatic compression mechanisms in nickel cyanide

    NASA Astrophysics Data System (ADS)

    Adamson, J.; Lucas, T. C.; Cairns, A. B.; Funnell, N. P.; Tucker, M. G.; Kleppe, A. K.; Hriljac, J. A.; Goodwin, A. L.

    2015-12-01

    We use variable-pressure neutron and X-ray diffraction measurements to determine the uniaxial and bulk compressibilities of nickel(II) cyanide, Ni(CN)2. Whereas other layered molecular framework materials are known to exhibit negative area compressibility, we find that Ni(CN)2 does not. We attribute this difference to the existence of low-energy in-plane tilt modes that provide a pressure-activated mechanism for layer contraction. The experimental bulk modulus we measure is about four times lower than that reported elsewhere on the basis of density functional theory methods [Phys. Rev. B 83 (2011) 024301].

  7. The evaluation of upper body muscle activity during the performance of external chest compressions in simulated hypogravity

    NASA Astrophysics Data System (ADS)

    Krygiel, Rebecca G.; Waye, Abigail B.; Baptista, Rafael Reimann; Heidner, Gustavo Sandri; Rehnberg, Lucas; Russomano, Thais

    2014-04-01

    BACKGROUND: This original study evaluated the electromyograph (EMG) activity of four upper body muscles: triceps brachii, erector spinae, upper rectus abdominis, and pectoralis major, while external chest compressions (ECCs) were performed in simulated Martian hypogravity using a Body Suspension Device, counterweight system, and standard full body cardiopulmonary resuscitation (CPR) mannequin. METHOD: 20 young, healthy male subjects were recruited. One hundred compressions divided into four sets, with roughly six seconds between each set to indicate 'ventilation', were performed within approximately a 1.5 minute protocol. Chest compression rate, depth and number were measured along with the subject's heart rate (HR) and rating of perceived exertion (RPE). RESULTS: All mean values were used in two-tailed t-tests using SPSS to compare +1 Gz values (control) versus simulated hypogravity values. The AHA (2005) compression standards were maintained in hypogravity. RPE and HR increased by 32% (p < 0.001) and 44% (p = 0.002), respectively, when ECCs were performed during Mars simulation, in comparison to +1 Gz. In hypogravity, the triceps brachii showed significantly less activity (p < 0.001) when compared with the other three muscles studied. The comparison of all the other muscles showed no difference at +1 Gz or in hypogravity. CONCLUSIONS: This study was among the first of its kind, however several limitations were faced which hopefully will not exist in future studies. Evaluation of a great number of muscles will allow space crews to focus on specific strengthening exercises within their current training regimes in case of a serious cardiac event in hypogravity.

  8. Compression failure mechanisms of composite structures

    NASA Technical Reports Server (NTRS)

    Hahn, H. T.; Sohi, M.; Moon, S.

    1986-01-01

    An experimental and analytical study was conducted to delineate the compression failure mechanisms of composite structures. The present report summarizes further results on kink band formation in unidirectional composites. In order to assess the compressive strengths and failure modes of fibers them selves, a fiber bundle was embedded in epoxy casting and tested in compression. A total of six different fibers were used together with two resins of different stiffnesses. The failure of highly anisotropic fibers such as Kevlar 49 and P-75 graphite was due to kinking of fibrils. However, the remaining fibers--T300 and T700 graphite, E-glass, and alumina--failed by localized microbuckling. Compressive strengths of the latter group of fibers were not fully utilized in their respective composite. In addition, acoustic emission monitoring revealed that fiber-matrix debonding did not occur gradually but suddenly at final failure. The kink band formation in unidirectional composites under compression was studied analytically and through microscopy. The material combinations selected include seven graphite/epoxy composites, two graphite/thermoplastic resin composites, one Kevlar 49/epoxy composite and one S-glass/epoxy composite.

  9. Mechanical properties of chest protectors and the likelihood of ventricular fibrillation due to commotio cordis.

    PubMed

    Drewniak, Elizabeth I; Spenciner, David B; Crisco, Joseph J

    2007-11-01

    Sudden death resulting from ventricular fibrillation (VF) caused by a nonpenetrating chest wall impact, known as commotio cordis (CC), is the second leading cause of death among young athletes. To date, seven young athletes wearing chest protectors have died from CC. The purpose of this study was to determine whether a relationship exists between mechanical properties of chest protectors and occurrence of VF, previously determined by Weinstock et al., using an established swine model. A servo-hydraulic material tester was used to determine properties of the chest protectors, including displacement, permanent deformation, stiffness, and area of pressure distribution. These properties were then compared with the occurrence of VF. We found that a decreased proportion of hits resulting in VF was significantly associated (R2 = 0.59, p = 0.001) with an increase in the area of pressure distribution. These findings are a limited, but crucial, first step in understanding the prevention of this complex and perplexing phenomenon. PMID:18089926

  10. Mechanical properties of lungs and chest wall during spontaneous breathing.

    PubMed

    Nagels, J; Làndsér, F J; van der Linden, L; Clément, J; Van de Woestijne, K P

    1980-09-01

    Using a forced oscillation technique, we measured the resistance (Rrs) and reactance (Xrs) of the respiratory system between 2 and 32 Hz at three different lung volumes in 15 healthy subjects and 7 patients with chronic obstructive pulmonary disease. Rrs and Xrs were partitioned, by means of a pressure recording in the esophagus, into the resistance and reactance of lung and airways (L) and the chest wall. The measurements were validated by checking the adequacy of the frequency response of the esophagus, by the lack of difference between thoracic and mouth flow, by an estimation of the error introduced by the shunt impedance of the cheeks, and by comparisons with the values of pulmonary compliance and resistance determined in the same subjects with classical techniques. In both healthy subjects and patients, the chest wall has a low resistance that increases somewhat at low lung volumes and behaves functionally as a two-compartment system, with low capacitance at frequencies exceeding 4 Hz. Rrs varies with lung volume and is markedly frequency dependent in patients; both phenomena are due primarily to corresponding variations of RL. In healthy subjects, at and above functional residual capacity (FRC) level, the lungs behave as a one-compartment system, the reactance of which is mainly determined by the gaseous inertance, at least beyond 2 Hz. In patients and in healthy subjects breathing below FRC, the observed frequency dependence of resistance and the simultaneous increase in resonant frequency can be simulated satisfactorily by Mead's two-compartment model, assuming a large increase in peripheral airways resistance. PMID:7204163

  11. Survival with good neurological outcome in a patient with prolonged ischemic cardiac arrest--utility of automated chest compression systems in the cardiac catheterization laboratory.

    PubMed

    Psaltis, Peter J; Meredith, Ian T; Ahmar, Walid

    2014-11-15

    The management of refractory cardiac arrest during invasive coronary procedures has substantial logistical challenges and is typically associated with disappointing outcomes. We describe the case of a young woman with recalcitrant ventricular fibrillation due to acute anterior ST-elevation myocardial infarction caused by occlusion of her proximal left anterior descending artery. Survival without neurological deficit or organ failure was achieved following primary percutaneous reperfusion and a total of 52 min of intra-procedural chest compression support, made possible by the use of an automated chest compression device. PMID:24403102

  12. Mechanical Metamaterials with Negative Compressibility Transitions

    NASA Astrophysics Data System (ADS)

    Motter, Adilson

    2015-03-01

    When tensioned, ordinary materials expand along the direction of the applied force. In this presentation, I will explore network concepts to design metamaterials exhibiting negative compressibility transitions, during which the material undergoes contraction when tensioned (or expansion when pressured). Such transitions, which are forbidden in thermodynamic equilibrium, are possible during the decay of metastable, super-strained states. I will introduce a statistical physics theory for negative compressibility transitions, derive a first-principles model to predict these transitions, and present a validation of the model using molecular dynamics simulations. Aside from its immediate mechanical implications, our theory points to a wealth of analogous inverted responses, such as inverted susceptibility or heat-capacity transitions, allowed when considering realistic scales. This research was done in collaboration with Zachary Nicolaou, and was supported by the National Science Foundation and the Alfred P. Sloan Foundation.

  13. Systematic investigation of compression mechanisms of clinoenstatite

    NASA Astrophysics Data System (ADS)

    Lazarz, J. D.; Dera, P.; Bina, C. R.; Jacobsen, S. D.

    2015-12-01

    Pyroxenes are a major component of the Earth's upper mantle and believed to be stable to approximately 16 GPa, along the oceanic geotherm. However, under certain conditions such as subducting slabs, it is possible to carry pyroxenes to much greater depths within the mantle. Pyroxenes penetrating the mantle to such depths could potentially undergo further phase transitions which could impact subducting slab mineralogy and mantle dynamics. The compression behavior of clinopyroxenes has been well characterized up to approximately 25 GPa with much of the work being focused on Ca-rich cpx. Beyond 10 GPa previous studies have published equations of state but there is a general lack of structure determinations. Ca-rich clinopyroxenes crystallize in the C2/c space group while Ca-poor clinopyroxenes crystalize in P21/c. It has been shown that P21/c clinopyroxenes reversibly transform to C2/c upon increased pressure, temperature, and M2 site cation size. The critical pressure for this transition is exceedingly compositionally dependent at 6.5 GPa and 1.7 GPa for clinoenstatite and clinoferrosilite, respectively. The strong compositional dependence of phase transitions in pyroxenes is motivation for a more complete understanding of compression mechanisms within the broad pyroxene category. By using in situ x-ray diffraction and diamond anvil cells to compress single-crystal clinoenstatite up to 50 GPa this study aims to expand the understanding of Ca-poor clinopyroxene compression mechanisms and elasticity. Here we report a fully reversible high-pressure phase in the P21/c space group found at approximately 45 GPa.

  14. Mechanisms and Clinical Management of Ventricular Arrhythmias following Blunt Chest Trauma

    PubMed Central

    Wolbrom, Daniel H.; Rahman, Aleef; Tschabrunn, Cory M.

    2016-01-01

    Nonpenetrating, blunt chest trauma is a serious medical condition with varied clinical presentations and implications. This can be the result of a dense projectile during competitive and recreational sports but may also include other etiologies such as motor vehicle accidents or traumatic falls. In this setting, the manifestation of ventricular arrhythmias has been observed both acutely and chronically. This is based on two entirely separate mechanisms and etiologies requiring different treatments. Ventricular fibrillation can occur immediately after chest wall injury (commotio cordis) and requires rapid defibrillation. Monomorphic ventricular tachycardia can develop in the chronic stage due to underlying structural heart disease long after blunt chest injury. The associated arrhythmogenic tissue may be complex and provides the necessary substrate to form a reentrant VT circuit. Ventricular tachycardia in the absence of overt structural heart disease appears to be focal in nature with rapid termination during ablation. Regardless of the VT mechanism, patients with recurrent episodes, despite antiarrhythmic medication in the chronic stage following blunt chest injury, are likely to require ablation to achieve VT control. This review article will describe the mechanisms, pathophysiology, and treatment of ventricular arrhythmias that occur in both the acute and chronic stages following blunt chest trauma. PMID:26981308

  15. Optimal chest compression in cardiopulmonary resuscitation depends upon thoracic and back support stiffness.

    PubMed

    Dellimore, Kiran H; Scheffer, Cornie

    2012-12-01

    A biomechanical analysis of the constant peak displacement and constant peak force methods of cardiopulmonary resuscitation (CPR) has revealed that optimal CC performance strongly depends on back support stiffness, CC rate, and the thoracic stiffness of the patient being resuscitated. Clinically the results presented in this study suggest that the stiffness of the back support surfaces found in many hospitals may be sub-optimal and that a backboard or a concrete floor can be used to enhance CC effectiveness. In addition, the choice of optimal CC rate and maximum sternal force applied by clinicians during peak force CPR is ought to be based on a general assessment of the patient's thoracic stiffness, taking into account the patient's age, gender, and physical condition; which is consistent with current clinical practice. In addition, it is important for clinicians to note that very high peak sternal forces, exceeding the limit above which severe chest wall trauma and abdominal injury occurs, may be required for optimal CC during peak force CPR on patients with very stiff chests. In these cases an alternative CPR technique may be more appropriate. PMID:23054380

  16. Impact of physical fitness and biometric data on the quality of external chest compression: a randomised, crossover trial

    PubMed Central

    2011-01-01

    Background During circulatory arrest, effective external chest compression (ECC) is a key element for patient survival. In 2005, international emergency medical organisations changed their recommended compression-ventilation ratio (CVR) from 15:2 to 30:2 to acknowledge the vital importance of ECC. We hypothesised that physical fitness, biometric data and gender can influence the quality of ECC. Furthermore, we aimed to determine objective parameters of physical fitness that can reliably predict the quality of ECC. Methods The physical fitness of 30 male and 10 female healthcare professionals was assessed by cycling and rowing ergometry (focussing on lower and upper body, respectively). During ergometry, continuous breath-by-breath ergospirometric measurements and heart rate (HR) were recorded. All participants performed two nine-minute sequences of ECC on a manikin using CVRs of 30:2 and 15:2. We measured the compression and decompression depths, compression rates and assessed the participants' perception of exhaustion and comfort. The median body mass index (BMI; male 25.4 kg/m2 and female 20.4 kg/m2) was used as the threshold for subgroup analyses of participants with higher and lower BMI. Results HR during rowing ergometry at 75 watts (HR75) correlated best with the quality of ECC (r = -0.57, p < 0.05). Participants with a higher BMI and better physical fitness performed better and showed less fatigue during ECC. These results are valid for the entire cohort, as well as for the gender-based subgroups. The compressions of female participants were too shallow and more rapid (mean compression depth was 32 mm and rate was 117/min with a CVR of 30:2). For participants with a lower BMI and higher HR75, the compression depth decreased over time, beginning after four minutes for the 15:2 CVR and after three minutes for the 30:2 CVR. Although found to be more exhausting, a CVR of 30:2 was rated as being more comfortable. Conclusion The quality of the ECC and fatigue can

  17. Timing positive-pressure ventilation during chest compression: the key to improving the thoracic pump?

    PubMed

    Chalkias, Athanasios; Xanthos, Theodoros

    2015-02-01

    Given the importance of increased coronary and cerebral perfusion pressure during cardiopulmonary resuscitation, the recommendation of limiting tidal volume and ventilation rate to 10 per minute in order not to inhibit venous return seems to be correct. However, although the resuscitation community believes that positive-pressure ventilation during cardiopulmonary resuscitation is bad for the circulation, proper timing of compression and ventilation may actually improve the circulation. PMID:24381094

  18. Should PEEP Titration Be Based on Chest Mechanics in Patients With ARDS?

    PubMed

    Kallet, Richard H

    2016-06-01

    Functional residual capacity (FRC) is essentially the alveolar volume and a determinant of both oxygenation and respiratory system compliance (CRS). ARDS decreases FRC, and sufficient PEEP restores FRC; thus, assessments of PEEP by its impact on oxygenation and CRS are intimately linked. PEEP also can ameliorate or aggravate ventilator-induced lung injury. Therefore, it can be argued that PEEP should be titrated primarily by its impact on CRS The pro position argues that the heterogeneous nature of lung injury and its unique presentation in individual patients results in an uncoupling between oxygenation and CRS Therefore, relying upon oxygenation alone may enhance lung injury and mortality risk, particularly in those with severe ARDS. The con argument is that the preponderance of preclinical and clinical evidence suggests that a relatively narrow range of PEEP is required to manage all but the most severe cases of ARDS. In addition, pathological alterations in chest wall compliance confuse the interpretation of chest mechanics. Moreover, ambiguities and technical limitations in advanced techniques, such as esophageal manometry and pressure-volume curves, add a layer of complexity that renders its broader application in all ARDS patients both impractical and unnecessary. Whether sophisticated monitoring of chest mechanics in severe ARDS might improve outcomes further is open to question and should be studied further. However, it is highly improbable that we will ever discover a PEEP strategy that optimizes all aspects of cardiorespiratory function and chest mechanics for individual patients suffering from ARDS. PMID:27235320

  19. Comparison of the Pentax Airwayscope, Glidescope Video Laryngoscope, and Macintosh Laryngoscope During Chest Compression According to Bed Height

    PubMed Central

    Kim, Wonhee; Lee, Yoonje; Kim, Changsun; Lim, Tae Ho; Oh, Jaehoon; Kang, Hyunggoo; Lee, Sanghyun

    2016-01-01

    Abstract We aimed to investigate whether bed height affects intubation performance in the setting of cardiopulmonary resuscitation and which type of laryngoscope shows the best performance at each bed height. A randomized crossover manikin study was conducted. Twenty-one participants were enrolled, and they were randomly allocated to 2 groups: group A (n = 10) and group B (n = 11). The participants underwent emergency endotracheal intubation (ETI) using the Airwayscope (AWS), Glidescope video laryngoscope, and Macintosh laryngoscope in random order while chest compression was performed. Each ETI was conducted at 2 levels of bed height (minimum bed height: 68.9 cm and maximum bed height: 101.3 cm). The primary outcomes were the time to intubation (TTI) and the success rate of ETI. The P value for statistical significance was set at 0.05 and 0.017 in post-hoc test. The success rate of ETI was always 100% regardless of the type of laryngoscope or the bed height. TTI was not significantly different between the 2 bed heights regardless of the type of laryngoscope (all P > 0.05). The time for AWS was the shortest among the 3 laryngoscopes at both bed heights (13.7 ± 3.6 at the minimum bed height and 13.4 ± 4.7 at the maximum bed height) (all P < 0.017). The TTI of Glidescope video laryngoscope was not significantly shorter than that of Macintosh laryngoscope at the minimum height (17.6 ± 4.0 vs 19.6 ± 4.8; P = 0.02). The bed height, whether adjusted to the minimum or maximum setting, did not affect intubation performance. In addition, regardless of the bed height, the intubation time with the video laryngoscopes, especially AWS, was significantly shorter than that with the direct laryngoscope during chest compression. PMID:26844477

  20. Comparison of the Pentax Airwayscope, Glidescope Video Laryngoscope, and Macintosh Laryngoscope During Chest Compression According to Bed Height.

    PubMed

    Kim, Wonhee; Lee, Yoonje; Kim, Changsun; Lim, Tae Ho; Oh, Jaehoon; Kang, Hyunggoo; Lee, Sanghyun

    2016-02-01

    We aimed to investigate whether bed height affects intubation performance in the setting of cardiopulmonary resuscitation and which type of laryngoscope shows the best performance at each bed height.A randomized crossover manikin study was conducted. Twenty-one participants were enrolled, and they were randomly allocated to 2 groups: group A (n = 10) and group B (n = 11). The participants underwent emergency endotracheal intubation (ETI) using the Airwayscope (AWS), Glidescope video laryngoscope, and Macintosh laryngoscope in random order while chest compression was performed. Each ETI was conducted at 2 levels of bed height (minimum bed height: 68.9  cm and maximum bed height: 101.3 cm). The primary outcomes were the time to intubation (TTI) and the success rate of ETI. The P value for statistical significance was set at 0.05 and 0.017 in post-hoc test.The success rate of ETI was always 100% regardless of the type of laryngoscope or the bed height. TTI was not significantly different between the 2 bed heights regardless of the type of laryngoscope (all P > 0.05). The time for AWS was the shortest among the 3 laryngoscopes at both bed heights (13.7  ±  3.6 at the minimum bed height and 13.4  ±  4.7 at the maximum bed height) (all P < 0.017). The TTI of Glidescope video laryngoscope was not significantly shorter than that of Macintosh laryngoscope at the minimum height (17.6  ±  4.0 vs 19.6  ±  4.8; P = 0.02).The bed height, whether adjusted to the minimum or maximum setting, did not affect intubation performance. In addition, regardless of the bed height, the intubation time with the video laryngoscopes, especially AWS, was significantly shorter than that with the direct laryngoscope during chest compression. PMID:26844477

  1. A chest physician's guide to mechanisms of sinonasal disease.

    PubMed

    Hox, V; Maes, T; Huvenne, W; Van Drunen, C; Vanoirbeek, J A; Joos, G; Bachert, C; Fokkens, W; Ceuppens, J L; Nemery, B; Hellings, P W

    2015-04-01

    The upper and lower airways are closely linked from an anatomical, histological and immunological point of view, with inflammation in one part of the airways influencing the other part. Despite the concept of global airway disease, the upper airways tend to be overlooked by respiratory physicians. We provide a clinical overview of the most important and recent insights in rhinitis and rhinosinusitis in relation to lower airway disease. We focus on the various exogenous and endogenous factors that play a role in the development and aggravation of chronic upper airway inflammation. In addition to the classical inhaled allergens or microorganisms with well-defined pathophysiological mechanisms in upper airway disease, environmental substances such as cigarette smoke, diesel exhaust particles and occupational agents affecting lower airway homeostasis have recently gained attention in upper airway research. We are only at the beginning of understanding the complex interplay between exogenous and endogenous factors like genetic, immunological and hormonal influences on chronic upper airway inflammation. From a clinical perspective, the involvement of upper and lower airway disease in one patient can only be fully appreciated by doctors capable of understanding the interplay between upper and lower airway inflammation. PMID:25563773

  2. Comparative Effectiveness of Emergency Resuscitative Thoracotomy versus Closed Chest Compressions among Patients with Critical Blunt Trauma: A Nationwide Cohort Study in Japan

    PubMed Central

    Suzuki, Kodai; Inoue, Shigeaki; Morita, Seiji; Watanabe, Nobuo; Shintani, Ayumi; Inokuchi, Sadaki; Ogura, Shinji

    2016-01-01

    Background Although emergency resuscitative thoracotomy is performed as a salvage maneuver for critical blunt trauma patients, evidence supporting superior effectiveness of emergency resuscitative thoracotomy compared to conventional closed-chest compressions remains insufficient. The objective of this study was to investigate whether emergency resuscitative thoracotomy at the emergency department or in the operating room was associated with favourable outcomes after blunt trauma and to compare its effectiveness with that of closed-chest compressions. Methods This was a retrospective nationwide cohort study. Data were obtained from the Japan Trauma Data Bank for the period between 2004 and 2012. The primary and secondary outcomes were patient survival rates 24 h and 28 d after emergency department arrival. Statistical analyses were performed using multivariable generalized mixed-effects regression analysis. We adjusted for the effects of different hospitals by introducing random intercepts in regression analysis to account for the differential quality of emergency resuscitative thoracotomy at hospitals where patients in cardiac arrest were treated. Sensitivity analyses were performed using propensity score matching. Results In total, 1,377 consecutive, critical blunt trauma patients who received cardiopulmonary resuscitation in the emergency department or operating room were included in the study. Of these patients, 484 (35.1%) underwent emergency resuscitative thoracotomy and 893 (64.9%) received closed-chest compressions. Compared to closed-chest compressions, emergency resuscitative thoracotomy was associated with lower survival rate 24 h after emergency department arrival (4.5% vs. 17.5%, respectively, P < 0.001) and 28 d after arrival (1.2% vs. 6.0%, respectively, P < 0.001). Multivariable generalized mixed-effects regression analysis with and without a propensity score-matched dataset revealed that the odds ratio for an unfavorable survival rate after 24 h

  3. Clinical study on VATS combined mechanical ventilation treatment of ARDS secondary to severe chest trauma

    PubMed Central

    Qi, Yongjun

    2016-01-01

    The aim of the study was to investigate the clinical effects of microinvasive video-assisted thoracoscopic surgery (VATS) combined with mechanical ventilation in the treatment of acute respiratory distress syndrome (ARDS) secondary to severe chest trauma. A total of 62 patients with ARDS secondary to severe chest trauma were divided into the observation and control groups. The patients in the observation groups were treated with VATS combined with early mechanical ventilation while patients in the control group were treated using routine open thoracotomy combined with early mechanical ventilation. Compared to the controls, the survival rate of the observation group was significantly higher. The average operation time of the observation group was significantly shorter than that of the control group, and the incidence of complications in the perioperative period of the observation group was significantly lower than that of the control group (p<0.05). The average application time of the observation group was significantly shorter than that of the control group, and the incidence of ventilator-associated complications was significantly lower than that of the control group (p<0.05). In conclusion, a reasonable understanding of the indications and contraindications of VATS, combined with early mechanical treatment significantly improved the success rate of the treatment of ARDS patients secondary to severe chest trauma and reduced the complications. PMID:27446317

  4. Severe Pulmonary Valve Regurgitation 40 Years After Blunt Chest Trauma.

    PubMed

    Fuglsang, Simon; Heiberg, Johan; Hjortdal, Vibeke Elisabeth

    2015-10-01

    Severe pulmonary valve regurgitation caused by a pulmonary valve tear is a rare complication to a blunt chest trauma. In this case report, we present a patient with pulmonary regurgitation originating from a chest trauma 40 years ago. Possible mechanisms are osseous pinch of the pulmonary valve between the anterior chest wall and the vertebral column, and retrograde blowout from severe compression of the lungs. PMID:26434447

  5. In a Swine Model, Chest Compressions Cause Ventricular Capture, and By Means of a Long-Short Sequence, Ventricular Fibrillation

    PubMed Central

    Osorio, Jose; Dosdall, Derek J; Robichaux, Robert P; Tabereaux, Paul B.; Ideker, Raymond E

    2009-01-01

    Background During resuscitation, fibrillation often recurs. In swine, we studied refibrillation after long duration ventricular fibrillation (LDVF) investigating an association with chest compressions (CCs). Methods and Results In Protocol A, 47 episodes of LDVF lasting at least 2.5 min were induced in 8 animals. Following defibrillation, CCs were required for 35 episodes and delivered with a pneumatic device (Lucas-CPR). In 9 episodes, refibrillation occurred within 2 s of CC initiation (Group 1) and in 26 episodes CCs were delivered without refibrillation (Group 2). From the ECG and intracardiac electrodes, the RR interval preceding CCs, the shortest cycle length during the first 2 CCs (Short) and the preceding cycle length (Long) were measured. A similar study was conducted in 3 more animals without intracardiac catheters (Protocol B). In Protocol A, the mean RR before CC was 665±292ms in Group 1 and 769±316 in Group 2. CCs stimulated ventricular beats in all 35 episodes. The Short and Long intervals were shorter in Group 1 (215±31ms and 552±210ms), than in Group 2 (402±153ms and 699±147ms) (p=0.009 and p=0.04, respectively). The Prematurity Index (Short/RR) was lower in Group 1 (0.35±0.09) than Group 2 (0.58±0.21) (p<0.01). A Short interval < 231 ms predicted refibrillation with 88% sensitivity and 91% specificity. In Protocol B, CCs were required in 11 episodes, causing ventricular stimulation in all of them and VF within the first 2 CCs in 3. Conclusions Under some conditions, CC during resuscitation can stimulate the ventricles and initiate VF by a long-short sequence. PMID:19808420

  6. Inelastic deformation mechanisms in a transverse MMC lamina under compression

    NASA Technical Reports Server (NTRS)

    Newaz, Golam M.; Majumdar, Bhaskar S.

    1992-01-01

    An investigation was undertaken to study the inelastic deformation mechanisms in (90)(sub 8) Ti 15-3/SCS-6 lamina subjected to pure compression. Both mechanical behavior and microstructural evaluation were undertaken at room temperature, 538 and 650 C. Results indicate that mechanical response and deformation characteristics are significantly different in monotonic tension and compression. The inelastic deformation mechanisms in compression are controlled by radial fiber fracture, matrix plasticity and fiber-matrix debonding. The radial fiber fracture is a new damage mode observed for metal-matrix composites (MMC).

  7. A mechanical chest compressor closed-loop controller with an effective trade-off between blood flow improvement and ribs fracture reduction.

    PubMed

    Zhang, Guang; Wu, Taihu; Song, Zhenxing; Wang, Haitao; Lu, Hengzhi; Wang, Yalin; Wang, Dan; Chen, Feng

    2015-06-01

    Chest compression (CC) is a significant emergency medical procedure for maintaining circulation during cardiac arrest. Although CC produces the necessary blood flow for patients with heart arrest, improperly deep CC will contribute significantly to the risk of chest injury. In this paper, an optimal CC closed-loop controller for a mechanical chest compressor (OCC-MCC) was developed to provide an effective trade-off between the benefit of improved blood perfusion and the risk of ribs fracture. The trade-off performance of the OCC-MCC during real automatic mechanical CCs was evaluated by comparing the OCC-MCC and the traditional mechanical CC method (TMCM) with a human circulation hardware model based on hardware simulations. A benefit factor (BF), risk factor (RF) and benefit versus risk index (BRI) were introduced in this paper for the comprehensive evaluation of risk and benefit. The OCC-MCC was developed using the LabVIEW control platform and the mechanical chest compressor (MCC) controller. PID control is also employed by MCC for effective compression depth regulation. In addition, the physiological parameters model for MCC was built based on a digital signal processor for hardware simulations. A comparison between the OCC-MCC and TMCM was then performed based on the simulation test platform which is composed of the MCC, LabVIEW control platform, physiological parameters model for MCC and the manikin. Compared with the TMCM, the OCC-MCC obtained a better trade-off and a higher BRI in seven out of a total of nine cases. With a higher mean value of cardiac output (1.35 L/min) and partial pressure of end-tidal CO2 (15.7 mmHg), the OCC-MCC obtained a larger blood flow and higher BF than TMCM (5.19 vs. 3.41) in six out of a total of nine cases. Although it is relatively difficult to maintain a stable CC depth when the chest is stiff, the OCC-MCC is still superior to the TMCM for performing safe and effective CC during CPR. The OCC-MCC is superior to the TMCM in

  8. Mechanical metamaterials with negative compressibility transitions

    NASA Astrophysics Data System (ADS)

    Nicolaou, Zachary G.; Motter, Adilson E.

    2012-07-01

    When tensioned, ordinary materials expand along the direction of the applied force. Here, we explore network concepts to design metamaterials exhibiting negative compressibility transitions, during which a material undergoes contraction when tensioned (or expansion when pressured). Continuous contraction of a material in the same direction of an applied tension, and in response to this tension, is inherently unstable. The conceptually similar effect we demonstrate can be achieved, however, through destabilizations of (meta)stable equilibria of the constituents. These destabilizations give rise to a stress-induced solid-solid phase transition associated with a twisted hysteresis curve for the stress-strain relationship. The strain-driven counterpart of negative compressibility transitions is a force amplification phenomenon, where an increase in deformation induces a discontinuous increase in response force. We suggest that the proposed materials could be useful for the design of actuators, force amplifiers, micromechanical controls, and protective devices.

  9. Mechanical metamaterials with negative compressibility transitions.

    PubMed

    Nicolaou, Zachary G; Motter, Adilson E

    2012-07-01

    When tensioned, ordinary materials expand along the direction of the applied force. Here, we explore network concepts to design metamaterials exhibiting negative compressibility transitions, during which a material undergoes contraction when tensioned (or expansion when pressured). Continuous contraction of a material in the same direction of an applied tension, and in response to this tension, is inherently unstable. The conceptually similar effect we demonstrate can be achieved, however, through destabilizations of (meta)stable equilibria of the constituents. These destabilizations give rise to a stress-induced solid-solid phase transition associated with a twisted hysteresis curve for the stress-strain relationship. The strain-driven counterpart of negative compressibility transitions is a force amplification phenomenon, where an increase in deformation induces a discontinuous increase in response force. We suggest that the proposed materials could be useful for the design of actuators, force amplifiers, micromechanical controls, and protective devices. PMID:22609557

  10. Mechanisms and effects of mechanical compression and dimensional change in polymer electrolyte fuel cells - A review

    NASA Astrophysics Data System (ADS)

    Millichamp, Jason; Mason, Thomas J.; Neville, Tobias P.; Rajalakshmi, Natarajan; Jervis, Rhodri; Shearing, Paul R.; Brett, Daniel J. L.

    2015-06-01

    Conventional polymer electrolyte fuel cells (PEFCs) require a means of placing the series of laminar components that make up cells under mechanical compression so as to ensure effective electrical conduction, mass transport and gas-tight operation. This review describes the effect of mechanical compression and dimensional change on the components of PEFCs and reviews the range of methods used to achieve desired stack compression. The case is made for improved understanding of the mechanisms of fuel cell component compression and greater attention to the development of technological approaches for stack compression.

  11. Mechanical compression drives cancer cells toward invasive phenotype

    PubMed Central

    Tse, Janet M.; Cheng, Gang; Tyrrell, James A.; Wilcox-Adelman, Sarah A.; Boucher, Yves; Jain, Rakesh K.; Munn, Lance L.

    2012-01-01

    Uncontrolled growth in a confined space generates mechanical compressive stress within tumors, but little is known about how such stress affects tumor cell behavior. Here we show that compressive stress stimulates migration of mammary carcinoma cells. The enhanced migration is accomplished by a subset of “leader cells” that extend filopodia at the leading edge of the cell sheet. Formation of these leader cells is dependent on cell microorganization and is enhanced by compressive stress. Accompanied by fibronectin deposition and stronger cell–matrix adhesion, the transition to leader-cell phenotype results in stabilization of persistent actomyosin-independent cell extensions and coordinated migration. Our results suggest that compressive stress accumulated during tumor growth can enable coordinated migration of cancer cells by stimulating formation of leader cells and enhancing cell–substrate adhesion. This novel mechanism represents a potential target for the prevention of cancer cell migration and invasion. PMID:22203958

  12. Statistical mechanics of lossy data compression using a nonmonotonic perceptron

    NASA Astrophysics Data System (ADS)

    Hosaka, Tadaaki; Kabashima, Yoshiyuki; Nishimori, Hidetoshi

    2002-12-01

    The performance of a lossy data compression scheme for uniformly biased Boolean messages is investigated via methods of statistical mechanics. Inspired by a formal similarity to the storage capacity problem in neural network research, we utilize a perceptron of which the transfer function is appropriately designed in order to compress and decode the messages. Employing the replica method, we analytically show that our scheme can achieve the optimal performance known in the framework of lossy compression in most cases when the code length becomes infinite. The validity of the obtained results is numerically confirmed.

  13. Which Fingers Should We Perform Two-Finger Chest Compression Technique with When Performing Cardiopulmonary Resuscitation on an Infant in Cardiac Arrest?

    PubMed

    Kim, Young Sinn; Oh, Je Hyeok; Kim, Chan Woong; Kim, Sung Eun; Lee, Dong Hoon; Hong, Jun Young

    2016-06-01

    This study compared the effectiveness two-finger chest compression technique (TFCC) performed using the right vs. left hand and the index-middle vs. middle-ring fingers. Four different finger/hand combinations were tested randomly in 30 healthcare providers performing TFCC (Test 1: the right index-middle fingers; Test 2: the left index-middle fingers; Test 3: the right middle-ring fingers; Test 4: the left middle-ring fingers) using two cross-over trials. The "patient" was a 3-month-old-infant-sized manikin. Each experiment consisted of cardiopulmonary resuscitation (CPR) consisting of 2 minutes of 30:2 compression: ventilation performed by one rescuer on a manikin lying on the floor as if in cardiac arrest. Ventilations were performed using the mouth-to-mouth method. Compression and ventilation data were collected during the tests. The mean compression depth (MCD) was significantly greater in TFCC performed with the index-middle fingers than with the middle-ring fingers regardless of the hand (95% confidence intervals; right hand: 37.8-40.2 vs. 35.2-38.6 mm, P = 0.002; left hand: 36.9-39.2 vs. 35.5-38.1 mm, P = 0.003). A deeper MCD was achieved with the index-middle fingers of the right versus the left hand (P = 0.004). The ratio of sufficiently deep compressions showed the same patterns. There were no significant differences in the other data. The best performance of TFCC in simulated 30:2 compression: ventilation CPR performed by one rescuer on an infant in cardiac arrest lying on the floor was obtained using the index-middle fingers of the right hand. Clinical Trial Registry at the Clinical Research Information Service (KCT0001515). PMID:27247512

  14. Which Fingers Should We Perform Two-Finger Chest Compression Technique with When Performing Cardiopulmonary Resuscitation on an Infant in Cardiac Arrest?

    PubMed Central

    2016-01-01

    This study compared the effectiveness two-finger chest compression technique (TFCC) performed using the right vs. left hand and the index-middle vs. middle-ring fingers. Four different finger/hand combinations were tested randomly in 30 healthcare providers performing TFCC (Test 1: the right index-middle fingers; Test 2: the left index-middle fingers; Test 3: the right middle-ring fingers; Test 4: the left middle-ring fingers) using two cross-over trials. The “patient” was a 3-month-old-infant-sized manikin. Each experiment consisted of cardiopulmonary resuscitation (CPR) consisting of 2 minutes of 30:2 compression: ventilation performed by one rescuer on a manikin lying on the floor as if in cardiac arrest. Ventilations were performed using the mouth-to-mouth method. Compression and ventilation data were collected during the tests. The mean compression depth (MCD) was significantly greater in TFCC performed with the index-middle fingers than with the middle-ring fingers regardless of the hand (95% confidence intervals; right hand: 37.8–40.2 vs. 35.2–38.6 mm, P = 0.002; left hand: 36.9–39.2 vs. 35.5–38.1 mm, P = 0.003). A deeper MCD was achieved with the index-middle fingers of the right versus the left hand (P = 0.004). The ratio of sufficiently deep compressions showed the same patterns. There were no significant differences in the other data. The best performance of TFCC in simulated 30:2 compression: ventilation CPR performed by one rescuer on an infant in cardiac arrest lying on the floor was obtained using the index-middle fingers of the right hand. Clinical Trial Registry at the Clinical Research Information Service (KCT0001515). PMID:27247512

  15. Effects of Constituent Properties on Compression Failure Mechanisms

    NASA Technical Reports Server (NTRS)

    Hahn, H. T.

    1984-01-01

    Compression failure mechanisms were investigated through the analysis of matrix-embedded fiber bundles. The use of fiber bundle specimens can provide much needed information on compression failure mechanisms because failure of the bundle is well contained and can be monitored during testing. The method can clearly distinguish between buckling-induced failure and shear-induced failure. The results indicate that WY and T300 graphite fibers and E-glass fiber fail in buckling while the high-modulus P75S graphite fiber fails in shear. Buckling-induced failure becomes more evident with low-modulus fiber in softer epoxy.

  16. Computerized detection of vertebral compression fractures on lateral chest radiographs: Preliminary results with a tool for early detection of osteoporosis

    SciTech Connect

    Kasai, Satoshi; Li Feng; Shiraishi, Junji; Li Qiang; Doi, Kunio

    2006-12-15

    Vertebral fracture (or vertebral deformity) is a very common outcome of osteoporosis, which is one of the major public health concerns in the world. Early detection of vertebral fractures is important because timely pharmacologic intervention can reduce the risk of subsequent additional fractures. Chest radiographs are used routinely for detection of lung and heart diseases, and vertebral fractures can be visible on lateral chest radiographs. However, investigators noted that about 50% of vertebral fractures visible on lateral chest radiographs were underdiagnosed or under-reported, even when the fractures were severe. Therefore, our goal was to develop a computerized method for detection of vertebral fractures on lateral chest radiographs in order to assist radiologists' image interpretation and thus allow the early diagnosis of osteoporosis. The cases used in this study were 20 patients with severe vertebral fractures and 118 patients without fractures, as confirmed by the consensus of two radiologists. Radiologists identified the locations of fractured vertebrae, and they provided morphometric data on the vertebral shape for evaluation of the accuracy of detecting vertebral end plates by computer. In our computerized method, a curved search area, which included a number of vertebral end plates, was first extracted automatically, and was straightened so that vertebral end plates became oriented horizontally. Edge candidates were enhanced by use of a horizontal line-enhancement filter in the straightened image, and a multiple thresholding technique, followed by feature analysis, was used for identification of the vertebral end plates. The height of each vertebra was determined from locations of identified vertebral end plates, and fractured vertebrae were detected by comparison of the measured vertebral height with the expected height. The sensitivity of our computerized method for detection of fracture cases was 95% (19/20), with 1.03 (139/135) false

  17. Clinical evaluation of the AutoPulse automated chest compression device for out-of-hospital cardiac arrest in the northern district of Shanghai, China

    PubMed Central

    Chen, Yuanzhuo; Peng, Hu; Chen, Yanqing; Zhuang, Yugang; Zhou, Shuqin

    2016-01-01

    Introduction Whether the AutoPulse automated chest compression device is worthy of clinical use for out-of-hospital cardiac arrest (OHCA) remains controversial. A prospective controlled study was conducted to evaluate the effect of AutoPulse versus manual chest compression for cardiopulmonary resuscitation (CPR) of OHCA patients in the northern district of Shanghai, China. Material and methods A total of 133 patients with OHCA who were treated at the Emergency Medical Center of the Tenth People's Hospital Affiliated with Tongji University between March 2011 and March 2012 were included. The patients were randomly assigned to the Manual CPR (n = 64) and AutoPulse CPR groups (n = 69) in accordance with the approach of chest compression received. The primary outcome measure was return of spontaneous circulation (ROSC), and the secondary outcome measures included 24-h survival rate, hospital discharge rate, and neurological prognosis at hospital discharge. Results The ROSC rate of patients with OHCA was significantly higher in the AutoPulse CPR group than in the Manual CPR group (44.9% vs. 23.4%; p = 0.009). The 24-h survival rate of OHCA patients was significantly higher in the AutoPulse CPR group than in the Manual CPR group (39.1% vs. 21.9%; p = 0.03). The hospital discharge rate of the patients with OHCA was significantly higher in the AutoPulse CPR group than in the Manual CPR group (18.8% vs. 6.3%; p = 0.03). The proportion of patients with OHCA and a cerebral performance category score of 1 or 2 points at hospital discharge was higher in the AutoPulse CPR group than in the Manual CPR group, but the difference was not statistically significant (16.2% vs. 13.4%, p = 1.00). Conclusions Use of the AutoPulse increases CPR success and survival rates in patients with OHCA, but its ability to improve cerebral performance requires further evaluation. PMID:27279849

  18. Compressive fracture morphology and mechanism of metallic glass

    NASA Astrophysics Data System (ADS)

    Qu, R. T.; Zhang, Z. F.

    2013-11-01

    We quantitatively investigated the fracture morphologies of Zr52.5Cu17.9Ni14.6Al10Ti5 and Pd78Cu6Si16 metallic glasses (MGs) under compression. The characteristic features of the compressive fracture morphology were captured, and the shear vein patterns were found to be not a one-to-one correspondence between two opposing fracture surfaces in an identical sample. This finding experimentally confirms that the compressive failure behaves in a fracture mode of pure shear (mode II). Quantitative measurements show that a ˜1 μm thickness layer with materials not only inside but also adjacent to the major shear band contributes to the formation of shear vein patterns. The critical shear strain to break a shear band was found to be more than 105% and higher in more ductile MGs under compression than tension. Estimation on the temperature rise at the fracture moment indicates that only ˜5% of the total elastic energy stored in the sample converts into the heat required for melting the layer to form the vein patterns. The mode II fracture toughness was also estimated based on the quantitative measurements of shear vein pattern and found larger than the mode I fracture toughness. Finally, the deformation and fracture mechanisms of MGs under tension and compression were compared and discussed. These results may improve the understanding on the fracture behaviors and mechanisms of MGs and may provide instructions on future design for ductile MGs with high resistance for fracture.

  19. Mechanical behavior of carpal tunnel subsynovial connective tissue under compression.

    PubMed

    Goetz, Jessica E; Baer, Thomas E

    2011-01-01

    Subsynovial connective tissue (SSCT) is a fluid-permeated loose connective tissue that occupies the majority of the space in the carpal tunnel not occupied by the digital flexor tendons or the median nerve. It is arranged in layers around these more discrete structures, presumably to assist with tendon gliding. As a result of this arrangement, the compressive behavior and the fluid permeability of this tissue may substantially affect the stresses in the median nerve resulting from contact with its neighboring tendons or with the walls of the tunnel itself. These stresses may contribute to damage of the median nerve and the development of carpal tunnel syndrome. In this study, the fluid permeability and the compressive behavior of the SSCT were investigated to better understand the mechanics of this tissue and how it may mediate mechanical insult to the median nerve. A custom experimental apparatus was built to allow simultaneous measurement of tissue compression and fluid flow. Using Darcy's law, the average SSCT fluid permeability was 8.78×10(15) m(4)/Ns. The compressive behavior of the SSCT demonstrated time dependence, with an initial modulus of 395kPa gradually decreasing to a value of 285kPa. These baseline tissue data may serve as a mechanical norm (toward which pathological tissue might be returned, therapeutically) and may serve as essential properties to include in future mechanical models of the carpal tunnel. PMID:22096431

  20. Mechanical properties of murine and porcine ocular tissues in compression.

    PubMed

    Worthington, Kristan S; Wiley, Luke A; Bartlett, Alexandra M; Stone, Edwin M; Mullins, Robert F; Salem, Aliasger K; Guymon, C Allan; Tucker, Budd A

    2014-04-01

    Sub-retinal implantation of foreign materials is becoming an increasingly common feature of novel therapies for retinal dysfunction. The ultimate compatibility of implants depends not only on their in vitro chemical compatibility, but also on how well the mechanical properties of the material match those of the native tissue. In order to optimize the mechanical properties of retinal implants, the mechanical properties of the mammalian retina itself must be carefully characterized. In this study, the compressive moduli of eye tissues, especially the retina, were probed using a dynamic mechanical analysis instrument in static mode. The retinal compressive modulus was lower than that of the sclera or cornea, but higher than that of the RPE and choroid. Compressive modulus remained relatively stable with age. Conversely, apparent retinal softening occurred at an early age in mice with inherited retinal degeneration. Compressive modulus is an important consideration for the design of retinal implants. Polymer scaffolds with moduli that are substantially different than that of the native tissue in which they will ultimately reside will be less likely to aid in the differentiation and development of the appropriate cell types in vitro and will have reduced biocompatibility in vivo. PMID:24613781

  1. MECHANICAL BEHAVIOR OF CARPAL TUNNEL SUBSYNOVIAL CONNECTIVE TISSUE UNDER COMPRESSION

    PubMed Central

    Goetz, Jessica E; Baer, Thomas E

    2011-01-01

    Subsynovial connective tissue (SSCT) is a fluid-permeated loose connective tissue that occupies the majority of the space in the carpal tunnel not occupied by the digital flexor tendons or the median nerve. It is arranged in layers around these more discrete structures, presumably to assist with tendon gliding. As a result of this arrangement, the compressive behavior and the fluid permeability of this tissue may substantially affect the stresses in the median nerve resulting from contact with its neighboring tendons or with the walls of the tunnel itself. These stresses may contribute to damage of the median nerve and the development of carpal tunnel syndrome. In this study, the fluid permeability and the compressive behavior of the SSCT were investigated to better understand the mechanics of this tissue and how it may mediate mechanical insult to the median nerve. A custom experimental apparatus was built to allow simultaneous measurement of tissue compression and fluid flow. Using Darcy’s law, the average SSCT fluid permeability was 8.78×1015 m4/Ns. The compressive behavior of the SSCT demonstrated time dependence, with an initial modulus of 395kPa gradually decreasing to a value of 285kPa. These baseline tissue data may serve as a mechanical norm (toward which pathological tissue might be returned, therapeutically) and may serve as essential properties to include in future mechanical models of the carpal tunnel. PMID:22096431

  2. Poroelastic Mechanical Effects of Hemicelluloses on Cellulosic Hydrogels under Compression

    PubMed Central

    Lopez-Sanchez, Patricia; Cersosimo, Julie; Wang, Dongjie; Flanagan, Bernadine; Stokes, Jason R.; Gidley, Michael J.

    2015-01-01

    Hemicelluloses exhibit a range of interactions with cellulose, the mechanical consequences of which in plant cell walls are incompletely understood. We report the mechanical properties of cell wall analogues based on cellulose hydrogels to elucidate the contribution of xyloglucan or arabinoxylan as examples of two hemicelluloses displaying different interactions with cellulose. We subjected the hydrogels to mechanical pressures to emulate the compressive stresses experienced by cell walls in planta. Our results revealed that the presence of either hemicellulose increased the resistance to compression at fast strain rates. However, at slow strain rates, only xyloglucan increased composite strength. This behaviour could be explained considering the microstructure and the flow of water through the composites confirming their poroelastic nature. In contrast, small deformation oscillatory rheology showed that only xyloglucan decreased the elastic moduli. These results provide evidence for contrasting roles of different hemicelluloses in plant cell wall mechanics and man-made cellulose-based composite materials. PMID:25794048

  3. Lung and chest wall mechanics in patients with acquired immunodeficiency syndrome and severe Pneumocystis carinii pneumonia.

    PubMed

    D'Angelo, E; Calderini, E; Robatto, F M; Puccio, P; Milic-Emili, J

    1997-10-01

    The aim of this study was to assess the mechanical characteristics of the respiratory system in patients with acquired immune deficiency syndrome (AIDS) and acute respiratory distress syndrome (ARDS) caused by Pneumocystis carinii pneumonia (PCP). In 12 mechanically ventilated patients, total respiratory system mechanics was assessed using the technique of rapid airway occlusion during constant flow inflation, and was partitioned into lung and chest wall components using the oesophageal balloon technique. We measured interrupter resistance (Rint), which mainly reflects airway resistance, additional resistance (deltaR) due to viscoelastic behaviour and time constant inequalities, and static elastance (Est). In addition, the static inflation volume-pressure (V-P) curve was assessed. In eight patients, computed tomography scans were performed within 2 days of the assessment of respiratory mechanics. Compared to values reported in the literature for normal subjects, Est and deltaR were markedly increased in AIDS patients with PCP, whilst Rint exhibited a relatively smaller increase. These changes, which involved only the lung and airways, were mainly due to the reduction of ventilated lung units, but additional factors were involved to cause independent modifications of lung stiffness, airway calibre, and viscoelastic properties. The changes in Rint, deltaR, and Est were similar to those observed in other studies on patients with ARDS of different aetiologies. At variance with common observations in the latter patients, none of the AIDS patients with PCP exhibited an inflection point on the static inflation V-P curve, suggesting little or no alveolar recruitment during lung inflation. This finding could be related to the distinctive histopathology of Pneumocystis carinii pneumonia. Indeed, computed tomography revealed homogeneous diffuse interstitial and alveolar infiltration rather than the dense, dependent opacities observed in other studies on acute respiratory

  4. Mechanisms of compressive failure in woven composites and stitched laminates

    NASA Technical Reports Server (NTRS)

    Cox, B. N.; Dadkhah, M. S.; Inman, R. V.; Morris, W. L.; Schroeder, S.

    1992-01-01

    Stitched laminates and angle interlock woven composites have been studied in uniaxial, in-plane, monotonic compression. Failure mechanisms have been found to depend strongly on both the reinforcement architecture and the degree of constraint imposed by the loading grips. Stitched laminates show higher compressive strength, but are brittle, possessing no load bearing capacity beyond the strain for peak load. Post-mortem inspection shows a localized shear band of buckled and broken fibers, which is evidently the product of an unstably propagating kink band. Similar shear bands are found in the woven composites if the constraint of lateral displacements is weak; but, under strong constraint, damage is not localized but distributed throughout the gauge section. While the woven composites tested are weaker than the stitched laminates, they continue to bear significant loads to compressive strains of approx. 15 percent, even when most damage is confined to a shear band.

  5. Dynamic Compression Effects on Intervertebral Disc Mechanics and Biology

    PubMed Central

    Korecki, Casey L.; MacLean, Jeffrey J.; Iatridis, James C.

    2008-01-01

    Study Design A bovine intervertebral disc organ culture model was used to study the effect of dynamic compression magnitude on mechanical behavior and measurement of biosynthesis rate, cell viability, and mRNA expression. Objective The objective of this study was to examine the effect of loading magnitude on intervertebral disc mechanics and biology in an organ culture model. Summary of Background Data The in vivo and cell culture response of intervertebral disc cells to dynamic mechanical loading provides evidence the disc responds in a magnitude dependant manner. However, the ability to link mechanical behavior of the disc with biologic phenomena has been limited. A large animal organ culture system facilitates measurements of tissue mechanics and biologic response parameters on the same sample allowing a broader understanding of disc mechanobiology. Methods Bovine caudal intervertebral discs were placed in organ culture for 6 days and assigned to a static control or 1 of 2 dynamic compression loading protocols (0.2–1 MPa or 0.2–2.5 MPa) at 1 Hz for 1 hour for 5 days. Disc structure was assessed with measurements of dynamic modulus, creep, height loss, water content, and proteoglycan loss to the culture medium. Cellular responses were assessed through changes in cell viability, metabolism, and qRT-PCR analyses. Results Increasing magnitudes of compression increased disc modulus and creep; however, all mechanical parameters recovered each day. In the anulus, significant increases in gene expression for collagen I and a trend of increasing sulfate incorporation were observed. In the nucleus, increasing gene expression for collagen I and MMP3 was observed between magnitudes and between static controls and the lowest magnitude of loading. Conclusion Results support the hypothesis that biologic remodeling precedes damage to the intervertebral disc structure, that compression is a healthy loading condition for the disc, and further support the link between applied

  6. Cell death induced by mechanical compression on engineered muscle results from a gradual physiological mechanism.

    PubMed

    Wu, Yabin; van der Schaft, Daisy W J; Baaijens, Frank P; Oomens, Cees W J

    2016-05-01

    Deep tissue injury (DTI), a type of pressure ulcer, arises in the muscle layers adjacent to bony prominences due to sustained mechanical loading. DTI presents a serious problem in the clinic, as it is often not visible until reaching an advanced stage. One of the causes can be direct mechanical deformation of the muscle tissue and cell. The mechanism of cell death induced by mechanical compression was studied using bio-artificial skeletal muscle tissues. Compression was applied by placing weights on top of the constructs. The morphological changes of the cytoskeleton and the phosphorylation of mitogen-activated protein kinases (MAPK) under compression were investigated. Moreover, inhibitors for each of the three major MAPK groups, p38, ERK, and JNK, were applied separately to look at their roles in the compression caused apoptosis and necrosis. The present study for the first time showed that direct mechanical compression activates MAPK phosphorylation. Compression also leads to a gradual destruction of the cytoskeleton. The percentage apoptosis is strongly reduced by p38 and JNK inhibitors down to the level of the unloaded group. This phenomenon could be observed up to 24h after initiation of compression. Therefore, cell death in bio-artificial muscle tissue caused by mechanical compression is primarily caused by a physiological mechanism, rather than through a physical mechanism which kills the cell directly. These findings reveal insight of muscle cell death under mechanical compression. Moreover, the result indicates a potential clinical solution to prevent DTI by pre-treating with p38 or/and JNK inhibitors. PMID:26961799

  7. One-dimensional discrete LQR control of compression of the human chest impulsively loaded by fast moving point mass

    NASA Astrophysics Data System (ADS)

    Olejnik, Paweł; Awrejcewicz, Jan

    2011-05-01

    This paper uncovers some interesting extension of an optimal discrete control methodology partially included in Proceedings and presented at the international conference on "Dynamical Systems Theory and Applications". There has been applied a scheme for realisation of active control strategy with numerically estimated linear optimal quadratic index of performance in reduction of impact-induced deformation of human chest loaded by a point mass at the central point of upper-torso body. We focused on application of one active element attached between torso's upper back (looking from posterior direction) and a fixed support. As the practical result we provide values of quality and reaction matrices, some useful deformation and energy dissipation time-characteristics and the resulting shape of control force time-characteristics that would be the demanding one for a hypothetical real implementation.

  8. Compression under a mechanical counter pressure space suit glove

    NASA Technical Reports Server (NTRS)

    Waldie, James M A.; Tanaka, Kunihiko; Tourbier, Dietmar; Webb, Paul; Jarvis, Christine W.; Hargens, Alan R.

    2002-01-01

    Background: Current gas-pressurized space suits are bulky stiff shells severely limiting astronaut function and capability. A mechanical counter pressure (MCP) space suit in the form of a tight elastic garment could dramatically improve extravehicular activity (EVA) dexterity, but also be advantageous in safety, cost, mass and volume. The purpose of this study was to verify that a prototype MCP glove exerts the design compression of 200 mmHg, a pressure similar to the current NASA EVA suit. Methods: Seven male subjects donned a pressure measurement array and MCP glove on the right hand, which was placed into a partial vacuum chamber. Average compression was recorded on the palm, the bottom of the middle finger, the top of the middle finger and the dorsum of the hand at pressures of 760 (ambient), 660 and 580 mmHg. The vacuum chamber was used to simulate the pressure difference between the low breathing pressure of the current NASA space suits (approximately 200 mmHg) and an unprotected hand in space. Results: At ambient conditions, the MCP glove compressed the dorsum of the hand at 203.5 +/- 22.7 mmHg, the bottom of the middle finger at 179.4 +/- 16.0 mmHg, and the top of the middle finger at 183.8 +/- 22.6 mmHg. The palm compression was significantly lower (59.6 +/- 18.8 mmHg, p<0.001). There was no significant change in glove compression with the chamber pressure reductions. Conclusions: The MCP glove compressed the dorsum of the hand and middle finger at the design pressure.

  9. Use of Backboard and Deflation Improve Quality of Chest Compression When Cardiopulmonary Resuscitation Is Performed on a Typical Air Inflated Mattress Configuration

    PubMed Central

    Oh, Jaehoon; Chee, Youngjoon; Lim, Taeho; Song, Yeongtak; Cho, Youngsuk; Je, Sangmo

    2013-01-01

    No study has examined the effectiveness of backboards and air deflation for achieving adequate chest compression (CC) depth on air mattresses with the typical configurations seen in intensive care units. To determine this efficacy, we measured mattress compression depth (MCD, mm) on these surfaces using dual accelerometers. Eight cardiopulmonary resuscitation providers performed CCs on manikins lying on 4 different surfaces using a visual feedback system. The surfaces were as follows: A, a bed frame; B, a deflated air mattress placed on top of a foam mattress laid on a bed frame; C, a typical air mattress configuration with an inflated air mattress placed on a foam mattress laid on a bed frame; and D, C with a backboard. Deflation of the air mattress decreased MCD significantly (B; 14.74 ± 1.36 vs C; 30.16 ± 3.96, P < 0.001). The use of a backboard also decreased MCD (C; 30.16 ± 3.96 vs D; 25.46 ± 2.89, P = 0.002). However, deflation of the air mattress decreased MCD more than use of a backboard (B; 14.74 ± 1.36 vs D; 25.46 ± 2.89, P = 0.002). The use of a both a backboard and a deflated air mattress in this configuration reduces MCD and thus helps achieve accurate CC depth during cardiopulmonary resuscitation. PMID:23399985

  10. Tuning and synthesis of semiconductor nanostructures by mechanical compression

    SciTech Connect

    Fan, Hongyou; Li, Binsong

    2015-11-17

    A mechanical compression method can be used to tune semiconductor nanoparticle lattice structure and synthesize new semiconductor nanostructures including nanorods, nanowires, nanosheets, and other three-dimensional interconnected structures. II-VI or IV-VI compound semiconductor nanoparticle assemblies can be used as starting materials, including CdSe, CdTe, ZnSe, ZnS, PbSe, and PbS.

  11. Evaluation of the compressive mechanical properties of endoluminal metal stents.

    PubMed

    Schrader, S C; Beyar, R

    1998-06-01

    The mechanical properties of metal stents are important parameters in the consideration of stent design, matched to resist arterial recoil and vascular spasm. The purpose of this study was to develop a system for a standardized quantitative evaluation of the mechanical characteristics of various coronary stents. Several types of stents were compressed by external hydrostatic pressure. The stent diameter was assessed by placing a pair of small ultrasonic sono-crystals on the stent. From pressure-strain diagrams the ultimate strength and radial stiffness for each stent were determined. For all stents, except the MICRO-II and the Wiktor stent, the diameter decreased homogeneously until an ultimate compressive strength was exceeded, causing an abrupt collapse. Expanded to 3 mm, the mechanical behavior of the beStent, the Crown and the Palmaz-Schatz stent (PS153-series) were comparable. The spiral articulated Palmaz-Schatz stent showed twice the strength (1.26 atm) of the PS-153 (0.65 atm). The NIR stent yielded a maximum strength of 1.05 atm. The MICRO-II and the Wiktor stent did not collapse abruptly but rather showed a continuous decline of diameter with increasing external pressure. The Cardiocoil stent behaved in a fully elastic manner and showed the largest radial stiffness. Difference in mechanical properties between stents were documented using a new device specifically developed for that purpose. These mechanical stent parameters may have important clinical implications. PMID:9637441

  12. Mechanical response of collagen molecule under hydrostatic compression.

    PubMed

    Saini, Karanvir; Kumar, Navin

    2015-04-01

    Proteins like collagen are the basic building blocks of various body tissues (soft and hard). Collagen molecules find their presence in the skeletal system of the body where they bear mechanical loads from different directions, either individually or along with hydroxy-apatite crystals. Therefore, it is very important to understand the mechanical behavior of the collagen molecule which is subjected to multi-axial state of loading. The estimation of strains of collagen molecule along different directions resulting from the changes in hydrostatic pressure magnitude, can provide us new insights into its mechanical behavior. In the present work, full atomistic simulations have been used to study global (volumetric) as well as local (along different directions) mechanical properties of the hydrated collagen molecule which is subjected to different hydrostatic pressure magnitudes. To estimate the local mechanical properties, the strains of collagen molecule along its longitudinal and transverse directions have been acquired at different hydrostatic pressure magnitudes. In spite of non-homogeneous distribution of atoms within the collagen molecule, the calculated values of local mechanical properties have been found to carry the same order of magnitude along the longitudinal and transverse directions. It has been demonstrated that the values of global mechanical properties like compressibility, bulk modulus, etc. as well as local mechanical properties like linear compressibility, linear elastic modulus, etc. are functions of magnitudes of applied hydrostatic pressures. The mechanical characteristics of collagen molecule based on the atomistic model have also been compared with that of the continuum model in the present work. The comparison showed up orthotropic material behavior for the collagen molecule. The information on collagen molecule provided in the present study can be very helpful in designing the future bio-materials. PMID:25687001

  13. Damage mechanisms in uniaxial compression of single enamel rods.

    PubMed

    An, Bingbing; Wang, Raorao; Arola, Dwayne; Zhang, Dongsheng

    2015-02-01

    Enamel possesses a complex hierarchical structure, which bestows this tissue with unique mechanical properties. In this study, the mechanical behavior of single enamel rods was investigated under uniaxial compression. Numerical simulations were also performed using micromechanics models for individual enamel rods to identify the damage mechanisms contributing to the constitutive behavior. Experimental results showed that the single rods exhibited an elastic modulus ranging from 10~31 GPa, and that they undergo post-yield strain-hardening. The primary damage mode consisted of delamination within the assembly of mineral crystals. Results from numerical simulations suggest that strain localization within individual rods is responsible for the observed delamination, which is believed to arise from the non-uniform arrangement of mineral crystals. This mechanism was independent of mineral morphology and properties. The non-uniform crystal arrangement results in friction between crystals with different inclination angles and is believed to be responsible for the post-yield strain hardening behavior. PMID:25460920

  14. Return of spontaneous Circulation Is Not Affected by Different Chest Compression Rates Superimposed with Sustained Inflations during Cardiopulmonary Resuscitation in Newborn Piglets

    PubMed Central

    Li, Elliott S.; Cheung, Po-Yin; Lee, Tze-Fun; Lu, Min; O'Reilly, Megan

    2016-01-01

    Objective Recently, sustained inflations (SI) during chest compression (CC) have been suggested as an alternative to the current approach during neonatal resuscitation. However, the optimal rate of CC during SI has not yet been established. Our aim was to determine whether different CC rates during SI reduce time to return of spontaneous circulation (ROSC) and improve hemodynamic recovery in newborn piglets with asphyxia-induced bradycardia. Intervention and measurements Term newborn piglets were anesthetized, intubated, instrumented and exposed to 45-min normocapnic hypoxia followed by asphyxia. Resuscitation was initiated when heart rate decreased to 25% of baseline. Piglets were randomized into three groups: CC superimposed by SI at a rate of 90 CC per minute (SI+CC 90, n = 8), CC superimposed by SI at a rate of 120 CC per minute (SI+CC 120, n = 8), or a sham group (n = 6). Cardiac function, carotid blood flow, cerebral oxygenation and respiratory parameters were continuously recorded throughout the experiment. Main results Both treatment groups had similar time of ROSC, survival rates, hemodynamic and respiratory parameters during cardiopulmonary resuscitation. The hemodynamic recovery in the subsequent 4h was similar in both groups and was only slightly lower than sham-operated piglets at the end of experiment. Conclusion Newborn piglets resuscitated by SI+CC 120 did not show a significant advantage in ROSC, survival, and hemodynamic recovery as compared to those piglets resuscitated by SI+CC 90. PMID:27304210

  15. Vocal tract resonances in singing: variation with laryngeal mechanism for male operatic singers in chest and falsetto registers.

    PubMed

    Henrich Bernardoni, Nathalie; Smith, John; Wolfe, Joe

    2014-01-01

    Seven male operatic singers sang the same notes and vowels in their chest and their falsetto registers, covering the overlap frequency range where two main laryngeal mechanisms can be identified by means of electroglottography: M1 in chest register and M2 in falsetto register. Glottal contact quotients determined using electroglottography were typically lower by 0.27 in M2 than in M1. Vocal tract resonance frequencies were measured by using broadband excitation at the lips and found to be typically lower in M2 than in M1 sung at the same pitch and vowel; R1 typically by 65 Hz and R2 by 90 Hz. These shifts in tract resonances were only weakly correlated with the changes in the contact quotient or laryngeal height that were measured simultaneously. There was considerable variability in the resonance tuning strategies used by the singers, and no evidence of a uniform systematic tuning strategy used by all singers. A simple model estimates that the shifts in resonance frequencies are consistent with the effective glottal area in falsetto register (M2) being 60%-70% of its value in chest register (M1). PMID:24437789

  16. Mechanical behavior of enamel rods under micro-compression.

    PubMed

    Yilmaz, Ezgi D; Schneider, Gerold A

    2016-10-01

    Exploring the structural strategies behind the optimized mechanical performance of hierarchical materials has been a focal point of extensive research over the past decades. Dental enamel is one such natural material, comprising a complicated hierarchical structure with a high level of mineral content. Bundles of hydroxyapatite nanofibers (level-1) Ø: 50nm form enamel rods (level-2) Ø: 5µm, which constitute bands (level-3) Ø: 50µm. While a number of studies in the last decade using advanced fracture mechanical methods have revealed an increasing trend in the fracture toughness of enamel with each additional level of hierarchy, there is still no general agreement on how hierarchical structuring affects the stiffness and strength of enamel. In this study, we identified the stiffness and strength values of the isolated rods (level-2) via micro-compression. The rods were tested in three different orientations with respect to the loading direction: parallel, perpendicular and oblique. The highest stress level withstood before catastrophic fracture was observed to be ~1500MPa in perpendicular orientation. In the oblique loading, the specimens failed by shearing and exhibited a damage-tolerant deformation behavior, which was attributed to the conjugation spots identified between the rods and interrod sheets. The elastic modulus was ~60GPa on average and similar in all orientations. The isotropy in stiffness was attributed to the mineral contacts residing between rods. This was verified by an analytical model derived for level-1 and extended over higher hierarchical levels. The experimental results obtained at level-2 were comparable to the compressive strength and stiffness values reported for level-1 and bulk enamel in the literature. In general, our results suggest that hierarchy has only a minor influence on the compressive properties of enamel. PMID:27415405

  17. A mechanism for the compressive ignition of liquid monopropellants

    NASA Technical Reports Server (NTRS)

    Morrison, W. F.; Knapton, J. D.; Mandzy, J.

    1980-01-01

    Possible mechanisms for compressive ignition of liquid monopropellants are discussed. These mechanisms all involve the collapse of a gas filled bubble imbedded in the liquid. A model of the collapse of a gas bubble in an incompressible liquid and the combustion of the surrounding liquid after ignition occurs is presented. The effect of gas covolume, liquid density, the adiabatic exponent, rate of pressurization and prepressurization are investigated. Calculations for finite and infinite liquid volumes are also presented. Gas generation in the bubble is shown to have a significant effect on its evolution and the introduction of a surface enhancement factor leads to a runaway reaction. For the conditions considered, the reacting bubble oscillates at a frequency of about 35 kHz over the first 0.5 milliseconds. This frequency decreases as the surface enhancement factor is increased. The implication is that a one dimensional model of this process may be tractable from the standpoint of computer time.

  18. Levofloxacin decreased chest wall mechanical inhomogeneities and airway and vascular remodeling in rats with induced hepatopulmonary syndrome.

    PubMed

    Gaio, Eduardo; Amado, Veronica; Rangel, Leonardo; Huang, Wilson; Storck, Rodrigo; Melo-Silva, César Augusto

    2013-12-01

    The administration of antibiotics decreases bacterial translocation, reduces the activity of nitric oxide synthase and improves the gas exchange of hepatopulmonary syndrome (HPS) in rats. We hypothesized that levofloxacin could reduce HPS-induced respiratory mechanical inhomogeneities and airway and pulmonary vascular remodeling. We assessed the respiratory mechanical properties and lung tissue structure in 24 rats assigned to the control, HPS (eHPS) and HPS+levofloxacin (eHPS+L) groups. The administration of levofloxacin reduced the HPS-induced chest wall but not the lung mechanical inhomogeneities. The eHPS airway proportion of elastic fibers increased 20% but was similar between the control and eHPS+L groups. The eHPS vascular collagen increased 25% in eHPS but was similar between the control and eHPS+L groups. Compared to the control group, the vascular proportion of elastic fibers of the eHPS and eHPS+L groups increased by 60% and 16%, respectively. The administration of levofloxacin decreased the HPS-induced chest wall mechanical inhomogeneities and airway and vascular remodeling. PMID:23994178

  19. The effect of expiratory rib cage compression before endotracheal suctioning on the vital signs in patients under mechanical ventilation

    PubMed Central

    Bousarri, Mitra Payami; Shirvani, Yadolah; Agha-Hassan-Kashani, Saeed; Nasab, Nouredin Mousavi

    2014-01-01

    Background: In patients undergoing mechanical ventilation, mucus production and secretion is high as a result of the endotracheal tube. Because endotracheal suction in these patients is essential, chest physiotherapy techniques such as expiratory rib cage compression before endotracheal suctioning can be used as a means to facilitate mobilizing and removing airway secretion and improving alveolar ventilation. As one of the complications of mechanical ventilation and endotracheal suctioning is decrease of cardiac output, this study was carried out to determine the effect of expiratory rib cage compression before endotracheal suctioning on the vital signs in patients under mechanical ventilation. Materials and Methods: This study was a randomized clinical trial with a crossover design. The study subjects included 50 mechanically ventilated patients, hospitalized in intensive care wards of Valiasr and Mousavi hospitals in Zanjan, Iran. Subjects were selected by consecutive sampling and randomly allocated to groups 1 and 2. The patients received endotracheal suctioning with or without rib cage compression, with a minimum of 3 h interval between the two interventions. Expiratory rib cage compression was performed for 5 min before endotracheal suctioning. Vital signs were measured 5 min before and 15 and 25 min after endotracheal suctioning. Data were recorded on a data recording sheet. Data were analyzed using paired t-tests. Results: There were statistically significant differences in the means of vital signs measured 5 min before with 15 and 25 min after endotracheal suctioning with rib cage compression (P < 0. 01). There was no significant difference in the means of diastolic pressure measured 25 min after with baseline in this stage). But on the reverse mode, there was a significant difference between the means of pulse and respiratory rate 15 min after endotracheal suctioning and the baseline values (P < 0.002). This effect continued up to 25 min after endotracheal

  20. Compressive adaptive ghost imaging via sharing mechanism and fellow relationship.

    PubMed

    Huo, Yaoran; He, Hongjie; Chen, Fan

    2016-04-20

    For lower sampling rate and better imaging quality, a compressive adaptive ghost imaging is proposed by adopting the sharing mechanism and fellow relationship in the wavelet tree. The sharing mechanisms, including intrascale and interscale sharing mechanisms, and fellow relationship are excavated from the wavelet tree and utilized for sampling. The shared coefficients, which are part of the approximation subband, are localized according to the parent coefficients and sampled based on the interscale sharing mechanism and fellow relationship. The sampling rate can be reduced owing to the fact that some shared coefficients can be calculated by adopting the parent coefficients and the sampled sum of shared coefficients. According to the shared coefficients and parent coefficients, the proposed method predicts the positions of significant coefficients and samples them based on the intrascale sharing mechanism. The ghost image, reconstructed by the significant coefficients and the coarse image at the given largest scale, achieves better quality because the significant coefficients contain more detailed information. The simulations demonstrate that the proposed method improves the imaging quality at the same sampling rate and also achieves a lower sampling rate for the same imaging quality for different types of target object images in noise-free and noisy environments. PMID:27140111

  1. Blunt Chest Trauma in Mice after Cigarette Smoke-Exposure: Effects of Mechanical Ventilation with 100% O2.

    PubMed

    Wagner, Katja; Gröger, Michael; McCook, Oscar; Scheuerle, Angelika; Asfar, Pierre; Stahl, Bettina; Huber-Lang, Markus; Ignatius, Anita; Jung, Birgit; Duechs, Matthias; Möller, Peter; Georgieff, Michael; Calzia, Enrico; Radermacher, Peter; Wagner, Florian

    2015-01-01

    Cigarette smoking (CS) aggravates post-traumatic acute lung injury and increases ventilator-induced lung injury due to more severe tissue inflammation and apoptosis. Hyper-inflammation after chest trauma is due to the physical damage, the drop in alveolar PO2, and the consecutive hypoxemia and tissue hypoxia. Therefore, we tested the hypotheses that 1) CS exposure prior to blunt chest trauma causes more severe post-traumatic inflammation and thereby aggravates lung injury, and that 2) hyperoxia may attenuate this effect. Immediately after blast wave-induced blunt chest trauma, mice (n=32) with or without 3-4 weeks of CS exposure underwent 4 hours of pressure-controlled, thoraco-pulmonary compliance-titrated, lung-protective mechanical ventilation with air or 100% O2. Hemodynamics, lung mechanics, gas exchange, and acid-base status were measured together with blood and tissue cytokine and chemokine concentrations, heme oxygenase-1 (HO-1), activated caspase-3, and hypoxia-inducible factor 1-α (HIF-1α) expression, nuclear factor-κB (NF-κB) activation, nitrotyrosine formation, purinergic receptor 2X4 (P2XR4) and 2X7 (P2XR7) expression, and histological scoring. CS exposure prior to chest trauma lead to higher pulmonary compliance and lower PaO2 and Horovitz-index, associated with increased tissue IL-18 and blood MCP-1 concentrations, a 2-4-fold higher inflammatory cell infiltration, and more pronounced alveolar membrane thickening. This effect coincided with increased activated caspase-3, nitrotyrosine, P2XR4, and P2XR7 expression, NF-κB activation, and reduced HIF-1α expression. Hyperoxia did not further affect lung mechanics, gas exchange, pulmonary and systemic cytokine and chemokine concentrations, or histological scoring, except for some patchy alveolar edema in CS exposed mice. However, hyperoxia attenuated tissue HIF-1α, nitrotyrosine, P2XR7, and P2XR4 expression, while it increased HO-1 formation in CS exposed mice. Overall, CS exposure aggravated post

  2. Blunt Chest Trauma in Mice after Cigarette Smoke-Exposure: Effects of Mechanical Ventilation with 100 % O2

    PubMed Central

    Wagner, Katja; Gröger, Michael; McCook, Oscar; Scheuerle, Angelika; Asfar, Pierre; Stahl, Bettina; Huber-Lang, Markus; Ignatius, Anita; Jung, Birgit; Duechs, Matthias; Möller, Peter; Georgieff, Michael; Calzia, Enrico; Radermacher, Peter; Wagner, Florian

    2015-01-01

    Cigarette smoking (CS) aggravates post-traumatic acute lung injury and increases ventilator-induced lung injury due to more severe tissue inflammation and apoptosis. Hyper-inflammation after chest trauma is due to the physical damage, the drop in alveolar PO2, and the consecutive hypoxemia and tissue hypoxia. Therefore, we tested the hypotheses that 1) CS exposure prior to blunt chest trauma causes more severe post-traumatic inflammation and thereby aggravates lung injury, and that 2) hyperoxia may attenuate this effect. Immediately after blast wave-induced blunt chest trauma, mice (n=32) with or without 3-4 weeks of CS exposure underwent 4 hours of pressure-controlled, thoraco-pulmonary compliance-titrated, lung-protective mechanical ventilation with air or 100 % O2. Hemodynamics, lung mechanics, gas exchange, and acid-base status were measured together with blood and tissue cytokine and chemokine concentrations, heme oxygenase-1 (HO-1), activated caspase-3, and hypoxia-inducible factor 1-α (HIF-1α) expression, nuclear factor-κB (NF-κB) activation, nitrotyrosine formation, purinergic receptor 2X4 (P2XR4) and 2X7 (P2XR7) expression, and histological scoring. CS exposure prior to chest trauma lead to higher pulmonary compliance and lower PaO2 and Horovitz-index, associated with increased tissue IL-18 and blood MCP-1 concentrations, a 2-4-fold higher inflammatory cell infiltration, and more pronounced alveolar membrane thickening. This effect coincided with increased activated caspase-3, nitrotyrosine, P2XR4, and P2XR7 expression, NF-κB activation, and reduced HIF-1α expression. Hyperoxia did not further affect lung mechanics, gas exchange, pulmonary and systemic cytokine and chemokine concentrations, or histological scoring, except for some patchy alveolar edema in CS exposed mice. However, hyperoxia attenuated tissue HIF-1α, nitrotyrosine, P2XR7, and P2XR4 expression, while it increased HO-1 formation in CS exposed mice. Overall, CS exposure aggravated post

  3. Chest Pain

    MedlinePlus

    Having a pain in your chest can be scary. It does not always mean that you are having a heart attack. There can be many other causes, ... embolism Costochondritis - an inflammation of joints in your chest Some of these problems can be serious. Get ...

  4. [Chest pain].

    PubMed

    Horn, Benedikt

    2015-01-01

    Chest pain in ambulatory setting is predominantly not heart-associated. Most patients suffer from muskuloskeletal or functional (psychogenic) chest pain. Differential diagnosis covers aortic dissection, rib-fracture, shingles, GERD, Tietze-Syndrome, pulmonary embolism, pleuritis, pneumothorax, pleurodynia and metastatic disease. In most cases history, symptoms and signs allow a clinical diagnosis of high pretest-probability. PMID:25533261

  5. Mechanics of particulate composites with glassy polymer binders in compression

    PubMed Central

    Jordan, J. L.; Spowart, J. E.; Kendall, M. J.; Woodworth, B.; Siviour, C. R.

    2014-01-01

    Whether used as structural components in design or matrix materials for composites, the mechanical properties of polymers are increasingly important. The compressive response of extruded polymethyl methacrylate (PMMA) rod with aligned polymer chains and Al–Ni–PMMA particulate composites are investigated across a range of strain rates and temperatures. The particulate composites were prepared using an injection-moulding technique resulting in highly anisotropic microstructures. The mechanics of these materials are discussed in the light of theories of deformation for glassy polymers. The experimental data from this study are compared with PMMA results from the literature as well as epoxy-based composites with identical particulates. The PMMA exhibited the expected strain rate and temperature dependence and brittle failure was observed at the highest strain rates and lowest temperatures. The Al–Ni–PMMA composites were found to have similar stress–strain response to the PMMA with reduced strain softening after yield. Increasing volume fraction of particulates in the composite resulted in decreased strength. PMID:24711495

  6. Chest MRI

    MedlinePlus

    ... imaging test that uses powerful magnetic fields and radio waves to create pictures of the chest (thoracic area). ... no side effects from the magnetic fields and radio waves have been reported. The most common type of ...

  7. Chest MRI

    MedlinePlus

    ... Restrictive cardiomyopathy Superior vena cava (SVC) obstruction Thoracic aortic aneurysm Thymus tumor Tumors of the chest Consult your ... Restrictive cardiomyopathy SVC obstruction Swollen lymph nodes Thoracic aortic aneurysm Patient Instructions Abdominal aortic aneurysm repair - open - discharge ...

  8. Chest radiology

    SciTech Connect

    Reed, J.C.

    1990-01-01

    This book is a reference in plain chest film diagnosis provides a thorough background in the differential diagnosis of 22 of the most common radiologic patterns of chest disease. Each chapter is introduced with problem cases and a set of questions, followed by a tabular listing of the appropriate differential considerations. The book emphasizes plain films, CT and some MR scans are integrated to demonstrate how these modalities enhance the work of a case.

  9. Chest drainage.

    PubMed

    Carter, Chris

    2014-07-15

    As an intensive care nurse with experience of caring for critically ill patients in the UK and on deployed operations overseas, I found the CPD article useful in reviewing the pathophysiology of a pneumothorax, use of intrapleural chest drains, observations that should be recorded, and nursing care and management of a patient with an intrapleural chest drain. Reflecting on the time out activities in the CPD article was valuable. PMID:25005418

  10. [Chest trauma].

    PubMed

    Freixinet Gilart, Jorge; Ramírez Gil, María Elena; Gallardo Valera, Gregorio; Moreno Casado, Paula

    2011-01-01

    Chest trauma is a frequent problem arising from lesions caused by domestic and occupational activities and especially road traffic accidents. These injuries can be analyzed from distinct points of view, ranging from consideration of the most severe injuries, especially in the context of multiple trauma, to the specific characteristics of blunt and open trauma. In the present article, these injuries are discussed according to the involvement of the various thoracic structures. Rib fractures are the most frequent chest injuries and their diagnosis and treatment is straightforward, although these injuries can be severe if more than three ribs are affected and when there is major associated morbidity. Lung contusion is the most common visceral lesion. These injuries are usually found in severe chest trauma and are often associated with other thoracic and intrathoracic lesions. Treatment is based on general support measures. Pleural complications, such as hemothorax and pneumothorax, are also frequent. Their diagnosis is also straightforward and treatment is based on pleural drainage. This article also analyzes other complex situations, notably airway trauma, which is usually very severe in blunt chest trauma and less severe and even suitable for conservative treatment in iatrogenic injury due to tracheal intubation. Rupture of the diaphragm usually causes a diaphragmatic hernia. Treatment is always surgical. Myocardial contusions should be suspected in anterior chest trauma and in sternal fractures. Treatment is conservative. Other chest injuries, such as those of the great thoracic and esophageal vessels, are less frequent but are especially severe. PMID:21640287

  11. Chest x-ray

    MedlinePlus

    ... Images Aortic rupture, chest x-ray Lung cancer, frontal chest x-ray Adenocarcinoma - chest x-ray Coal ... cancer - chest x-ray Lung nodule, right middle lobe - chest x-ray Lung mass, right upper lung - ...

  12. A non-topological mechanism for negative linear compressibility.

    PubMed

    Binns, Jack; Kamenev, Konstantin V; Marriott, Katie E R; McIntyre, Garry J; Moggach, Stephen A; Murrie, Mark; Parsons, Simon

    2016-06-14

    Negative linear compressibility (NLC), the increase in a unit cell length with pressure, is a rare phenomenon in which hydrostatic compression of a structure promotes expansion along one dimension. It is usually a consequence of crystal structure topology. We show that the source of NLC in the Co(ii) citrate metal-organic framework UTSA-16 lies not in framework topology, but in the relative torsional flexibility of Co(ii)-centred tetrahedra compared to more rigid octahedra. PMID:27203683

  13. Impacts to the chest of PMHSs - Influence of impact location and load distribution on chest response.

    PubMed

    Holmqvist, Kristian; Svensson, Mats Y; Davidsson, Johan; Gutsche, Andreas; Tomasch, Ernst; Darok, Mario; Ravnik, Dean

    2016-02-01

    The chest response of the human body has been studied for several load conditions, but is not well known in the case of steering wheel rim-to-chest impact in heavy goods vehicle frontal collisions. The aim of this study was to determine the response of the human chest in a set of simulated steering wheel impacts. PMHS tests were carried out and analysed. The steering wheel load pattern was represented by a rigid pendulum with a straight bar-shaped front. A crash test dummy chest calibration pendulum was utilised for comparison. In this study, a set of rigid bar impacts were directed at various heights of the chest, spanning approximately 120mm around the fourth intercostal space. The impact energy was set below a level estimated to cause rib fracture. The analysed results consist of responses, evaluated with respect to differences in the impacting shape and impact heights on compression and viscous criteria chest injury responses. The results showed that the bar impacts consistently produced lesser scaled chest compressions than the hub; the Middle bar responses were around 90% of the hub responses. A superior bar impact provided lesser chest compression; the average response was 86% of the Middle bar response. For inferior bar impacts, the chest compression response was 116% of the chest compression in the middle. The damping properties of the chest caused the compression to decrease in the high speed bar impacts to 88% of that in low speed impacts. From the analysis it could be concluded that the bar impact shape provides lower chest criteria responses compared to the hub. Further, the bar responses are dependent on the impact location of the chest. Inertial and viscous effects of the upper body affect the responses. The results can be used to assess the responses of human substitutes such as anthropomorphic test devices and finite element human body models, which will benefit the development process of heavy goods vehicle safety systems. PMID:26687541

  14. A method for intermediate strain rate compression testing and study of compressive failure mechanism of Mg-Al-Zn alloy

    NASA Astrophysics Data System (ADS)

    Gupta, Nikhil; Luong, Dung D.; Rohatgi, Pradeep K.

    2011-05-01

    Obtaining meaningful information from the test results is a challenge in the split-Hopkinson pressure bar (SHPB) test method if the specimen does not fail during the test. Although SHPB method is now widely used for high strain rate testing, this limitation has made it difficult to use it for characterization of materials in the intermediate strain rate range (typically 10-1000 s-1). In the present work, a method is developed to characterize materials in the intermediate strain rate range using SHPB setup. In this method, the specimen is repeatedly tested under compression at a given strain rate until failure is achieved. The stress-strain graphs obtained from each test cycle are used to plot the master stress-strain graph for that strain rate. This method is used to study the strain rate dependence of compressive response of a Mg-Al-Zn alloy in the intermediate strain rate range. A remarkable difference is observed in the failure mechanism of the alloy under quasi-static and intermediate strain rate compression. Matrix cracking is the main failure mechanism under quasi-static compression, whereas shattering of intermetallic precipitates, along with plastic deformation of the matrix, is discovered to become prominent as the strain rate is increased.

  15. Temperature, moisture, and strain rate effects on the compressive mechanical behavior of Nylon 6/6

    SciTech Connect

    Kawahara, W.A.; Brandon, S.L.; Korellis, J.S.

    1988-04-01

    Material test results are presented for the mechanical behavior of Nylon 66 in compression. Static compression modes include direct compression, stress relaxation and creep. Dynamic direct compression results are included. Tests are performed at atmospheric pressure; strain rates range from 10/sup /minus/4/sec to 10/sup 2/sec; temperatures are 20, 65, 110, 150 and 200/degree/C; moisture levels are 0% (dry), 2% and 6% (saturated); true strains to /minus/0.25 are imposed. Our empirical Temperature-Moisture equivalence of 14/degree/C per 1% moisture is discussed with respect to the /open quotes/free volume/close quotes/ concept.

  16. Mechanics of the Compression Wood Response: II. On the Location, Action, and Distribution of Compression Wood Formation.

    PubMed

    Archer, R R; Wilson, B F

    1973-04-01

    A new method for simulation of cross-sectional growth provided detailed information on the location of normal wood and compression wood increments in two tilted white pine (Pinus strobus L.) leaders. These data were combined with data on stiffness, slope, and curvature changes over a 16-week period to make the mechanical analysis. The location of compression wood changed from the under side to a flank side and then to the upper side of the leader as the geotropic stimulus decreased, owing to compression wood action. Its location shifted back to a flank side when the direction of movement of the leader reversed. A model for this action, based on elongation strains, was developed and predicted the observed curvature changes with elongation strains of 0.3 to 0.5%, or a maximal compressive stress of 60 to 300 kilograms per square centimeter. After tilting, new wood formation was distributed so as to maintain consistent strain levels along the leaders in bending under gravitational loads. The computed effective elastic moduli were about the same for the two leaders throughout the season. PMID:16658408

  17. Tensile and compressive mechanical behavior of twinned silicon carbide nanowires

    SciTech Connect

    Wang, Zhiguo; Li, Jingbo; Gao, Fei; Weber, William J.

    2010-04-01

    Molecular dynamics simulations with the Tersoff potential were used to study the response of twinned SiC nanowires under tensile and compressive strains. The critical strain of the twinned nanowires can be enhanced by twin-stacking faults, and their critical strains are larger than those of perfect nanowires with the same diameters. Under axial tensile strain, the bonds of the nanowires are just stretched before failure. The failure behavior is found to depend on the twin segment thickness and the diameter of the nanowires. An atomic chain is observed for the thin nanowires with small twin segment thickness under tension strain. Under axial compressive strain, the collapse of the twinned SiC nanowires exhibits two differently failure modes, depending on the length and diameter of the nanowires, i.e. shell buckling for short length nanowires and columnar buckling for longer length nanowires.

  18. Automatic compression adjusting mechanism for internal combustion engines

    NASA Technical Reports Server (NTRS)

    Akkerman, J. W. (Inventor)

    1983-01-01

    Means for controlling the compression pressure in an internal combustion engine having one or more cylinders and subject to widely varying power output requirements are provided. Received between each crank pin and connecting rod is an eccentric sleeve selectively capable of rotation about the crank pin and/or inside the rod and for latching with the rod to vary the effective length of the connecting rod and thereby the clearance volume of the engine. The eccentric normally rotates inside the connecting rod during the exhaust and intake strokes but a latching pawl carried by the eccentric is movable radially outwardly to latch the rod and eccentric together during the compression and power strokes. A control valve responds to intake manifold pressure to time the supply of hydraulic fluid to move the latch-pawl outwardly, varying the effective rod length to maintain a substantially optimum firing chamber pressure at all intake manifold pressures.

  19. On the mechanical behavior of slender, slightly curved, compressed microbridges

    NASA Astrophysics Data System (ADS)

    Hallauer, W. L.; Ma, C.

    2011-06-01

    We consider a clamped-clamped, slender beam-column that is slightly curved in its unloaded static equilibrium state. Perhaps the best practical example of this type of structure is a microbeam used in sensing and actuating devices. If the clamped ends are forced toward each other, or if stiff supports inhibit axial expansion that is fostered by fabrication processes and/or operational heating, then the column bends beyond its initial curvature. If the axial force approaches the buckling load, then the static flexural deflection can be relatively large, greater than the column's depth. We show that the dependence of moderately large static deflection upon compressive force is mathematically linear, and that nonlinearity arises only in the relationship of column shortening to transverse deflection. This leads to a linear finite-element method for static structural analysis of non-uniform columns, with which we simulate the behavior of a 62.5 µm long microbridge of 0.5 µm thin-film gold. This microbridge was observed experimentally to bend 4-5 µm under compression. We also examine previous studies of bending vibration about moderately large static deflection. Calculations and experimental measurements of the dependence of the fundamental natural frequency on axial compression and initial curvature indicate practical significance relative to design of microbridge resonators.

  20. What Is Chest MRI?

    MedlinePlus

    ... page from the NHLBI on Twitter. What Is Chest MRI? Chest MRI (magnetic resonance imaging) is a safe, noninvasive ... creates detailed pictures of the structures in your chest, such as your chest wall, heart, and blood ...

  1. Mechanism of ventricular vulnerability to single premature stimuli in open-chest dogs.

    PubMed

    Chen, P S; Wolf, P D; Dixon, E G; Danieley, N D; Frazier, D W; Smith, W M; Ideker, R E

    1988-06-01

    To determine the mechanism of ventricular vulnerability to electrical stimulation, we simultaneously recorded from 120 transmural electrodes in a 35 X 20 X 5-mm portion of right ventricular infundibulum in seven dogs. Baseline pacing (S1) was performed from outside the mapped region followed by single premature stimulation (S2) of increasing strength at the center of the mapped region. In five of six episodes of ventricular fibrillation and 26 of 30 episodes of repetitive responses, complete reentrant pathways were observed. Earliest activation following S2 was not at the site of S2 stimulation but was at a point between the S1 and S2 sites of stimulation. Activation spread away from the early site toward the opposite side of the mapped region around the sides of an arc of block near the S2 site to form a "figure-of-eight." The activation fronts coalesced to activate the region around the S2 site last and, if the difference in times between activation at the early site and near the S2 site was large, reentered the tissue toward the S1 site. Ventricular refractory periods were determined in four dogs following S1 pacing; the regions with the greatest nonuniformity in the dispersion of refractoriness were not the regions of unidirectional block after S2 stimulation. Thus, 1) ventricular fibrillation and repetitive responses induced electrically with S1 and S2 stimuli at different ventricular sites arise by figure-of-eight reentry, 2) this reentry is caused by the ability of S2 stimulation both to prolong refractoriness near the S2 site and to initiate a propagated response in the region between the S1 and S2 sites, and 3) a nonuniform dispersion of refractoriness is not crucial for the electrical induction of reentry leading to ventricular fibrillation or repetitive responses when S1 and S2 stimuli are given at different locations on the right ventricular outflow tract. PMID:2454762

  2. Joining mechanism with stem tension and interlocked compression ring

    DOEpatents

    James, Allister W.; Morrison, Jay A.

    2012-09-04

    A stem (34) extends from a second part (30) through a hole (28) in a first part (22). A groove (38) around the stem provides a non-threaded contact surface (42) for a ring element (44) around the stem. The ring element exerts an inward force against the non-threaded contact surface at an angle that creates axial tension (T) in the stem, pulling the second part against the first part. The ring element is formed of a material that shrinks relative to the stem by sintering. The ring element may include a split collet (44C) that fits partly into the groove, and a compression ring (44E) around the collet. The non-threaded contact surface and a mating distal surface (48) of the ring element may have conic geometries (64). After shrinkage, the ring element is locked onto the stem.

  3. Structural basis for the nonlinear mechanics of fibrin networks under compression.

    PubMed

    Kim, Oleg V; Litvinov, Rustem I; Weisel, John W; Alber, Mark S

    2014-08-01

    Fibrin is a protein polymer that forms a 3D filamentous network, a major structural component of protective physiological blood clots as well as life threatening pathological thrombi. It plays an important role in wound healing, tissue regeneration and is widely employed in surgery as a sealant and in tissue engineering as a scaffold. The goal of this study was to establish correlations between structural changes and mechanical responses of fibrin networks exposed to compressive loads. Rheological measurements revealed nonlinear changes of fibrin network viscoelastic properties under dynamic compression, resulting in network softening followed by its dramatic hardening. Repeated compression/decompression enhanced fibrin clot stiffening. Combining fibrin network rheology with simultaneous confocal microscopy provided direct evidence of structural modulations underlying nonlinear viscoelasticity of compressed fibrin networks. Fibrin clot softening in response to compression strongly correlated with fiber buckling and bending, while hardening was associated with fibrin network densification. Our results suggest a complex interplay of entropic and enthalpic mechanisms accompanying structural changes and accounting for the nonlinear mechanical response in fibrin networks undergoing compressive deformations. These findings provide new insight into the fibrin clot structural mechanics and can be useful for designing fibrin-based biomaterials with modulated viscoelastic properties. PMID:24840618

  4. Structural basis for the nonlinear mechanics of fibrin networks under compression

    PubMed Central

    Kim, Oleg V.; Litvinov, Rustem I.; Weisel, John W.; Alber, Mark S.

    2014-01-01

    Fibrin is a protein polymer that forms a 3D filamentous network, a major structural component of protective physiological blood clots as well as life threatening pathological thrombi. It plays an important role in wound healing, tissue regeneration and is widely employed in surgery as a sealant and in tissue engineering as a scaffold. The goal of this study was to establish correlations between structural changes and mechanical responses of fibrin networks exposed to compressive loads. Rheological measurements revealed nonlinear changes of fibrin network viscoelastic properties under dynamic compression, resulting in network softening followed by its dramatic hardening. Repeated compression/decompression enhanced fibrin clot stiffening. Combining fibrin network rheology with simultaneous confocal microscopy provided direct evidence of structural modulations underlying nonlinear viscoelasticity of compressed fibrin networks. Fibrin clot softening in response to compression strongly correlated with fiber buckling and bending, while hardening was associated with fibrin network densification. Our results suggest a complex interplay of entropic and enthalpic mechanisms accompanying structural changes and accounting for the nonlinear mechanical response in fibrin networks undergoing compressive deformations. These findings provide new insight into the fibrin clot structural mechanics and can be useful for designing fibrin-based biomaterials with modulated viscoelastic properties. PMID:24840618

  5. Comparison of ventilation and chest compression performance by bystanders using the Impact Model 730 ventilator and a conventional bag valve with mask in a model of adult cardiopulmonary arrest.

    PubMed

    Hurst, Victor; West, Sarah; Austin, Paul; Branson, Richard; Beck, George

    2007-04-01

    "Bystanders" or lay persons are typically the first caregivers to attend to a victim of out-of-hospital cardiopulmonary arrest. Astronaut crew medical officers (CMO) play a similar role to bystanders aboard the International Space Station (ISS). Studies have demonstrated the importance of bystander cardiopulmonary resuscitation (BCPR) for patient survival before the arrival of emergency medical care. Recent apprehension from bystanders about the threat of contracting communicable diseases during BCPR, however, has led to the consideration of other ventilation systems such as the bag-valve mask (BVM) and automatic transport ventilators (ATV). BVM use is called for during CPR aboard the ISS. This study evaluated the ventilation and compression performance of 40 basic CPR-trained bystanders using either a BVM (adult-sized self-inflating bag with face mask) or an ATV (Model 730 ventilator (M730), Impact Instrumentation, Inc., West Caldwell, NJ). Each two-bystander team gave BCPR to a simulated cardiopulmonary arrest victim using the 2-breath/15-compression cycle for 4 min and then switched roles for another 4-min interval. Compared to BVM use, the M730 led to significantly (p<0.05) lower number of breaths, smaller tidal volumes, airway flows, airway pressures, volume of gas entering the stomach per breath and chest compressions for the 4-min period. The M730 also enabled a bystander to meet the recommendation of 4-breath and compression cycles per minute as per Guidelines 2000. Lastly, ease-of-use scores were significantly higher for the M730 compared to the BVM. Overall, the data suggest that the M730 improves the quality of performance for a bystander performing BCPR. PMID:17175090

  6. Failure mechanisms of notched laminated composites under compressive loading at room and elevated temperature

    NASA Astrophysics Data System (ADS)

    Ahn, Jung Hyun

    1999-10-01

    Understanding the mechanisms of failure of composite structures and developing mechanism based failure criteria are important considerations in designing structures made of composite materials. The compressive response of composite materials and structures has received considerable attention due to their significance in the aerospace industry and the complexity associated with compressive failure. Several competing failure mechanisms such as fiber instability, fiber/matrix interfacial failure, fiber microbuckling/kinking, delamination initiation and delamination buckling may become active in compressive loading. Environmental effect such as an elevated temperature can alter and affect these failure mechanisms. In this thesis, a micromechanics based finite element predictive model for notched strength of multidirectional laminates is presented. The in-situ shear response of the matrix, the fiber mechanical properties, the lay-up (stacking sequence) and fiber volume fraction serve as input to the model. The prediction of the model is found to match favorably with experimental data. The effect of ply angle and its influence on the failure mechanism are quantified and compared with a set of available experimental data. The present work is the first development of a non-empirical mechanics based failure prediction methodology for notched compressive strength of composite laminates. Both an experimental and an analytical study are presented herein.

  7. Simulated effect on the compressive and shear mechanical properties of bionic integrated honeycomb plates.

    PubMed

    He, Chenglin; Chen, Jinxiang; Wu, Zhishen; Xie, Juan; Zu, Qiao; Lu, Yun

    2015-05-01

    Honeycomb plates can be applied in many fields, including furniture manufacturing, mechanical engineering, civil engineering, transportation and aerospace. In the present study, we discuss the simulated effect on the mechanical properties of bionic integrated honeycomb plates by investigating the compressive and shear failure modes and the mechanical properties of trabeculae reinforced by long or short fibers. The results indicate that the simulated effect represents approximately 80% and 70% of the compressive and shear strengths, respectively. Compared with existing bionic samples, the mass-specific strength was significantly improved. Therefore, this integrated honeycomb technology remains the most effective method for the trial manufacturing of bionic integrated honeycomb plates. The simulated effect of the compressive rigidity is approximately 85%. The short-fiber trabeculae have an advantage over the long-fiber trabeculae in terms of shear rigidity, which provides new evidence for the application of integrated bionic honeycomb plates. PMID:25746272

  8. Boron Nitride Coated Carbon Nanotube Arrays with Enhanced Compressive Mechanical Property

    NASA Astrophysics Data System (ADS)

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Tan, Dunlin; Zhang, Bowei; Tok, Alfred Iing Yoong; Teo, Edwin Hang Tong

    Vertically aligned carbon nanotube (CNT) array is one of the most promising energy dissipating materials due to its excellent temperature invariant mechanical property. However, the CNT arrays with desirable recoverability after compression is still a challenge. Here, we report on the mechanical enhancement of the CNT arrays reinforced by coating with boron nitride (BN) layers. These BN coated CNT (BN/CNT) arrays exhibit excellent compressive strength and recoverability as compared to those of the as-prepared CNT arrays which totally collapsed after compression. In addition, the BN coating also provides better resistance to oxidation due to its intrinsic thermal stability. This work presented here opens a new pathway towards tuning mechanical behavior of any arbitrary CNT arrays for promising potential such as damper, vibration isolator and shock absorber applications.

  9. Optimization of the dye-sensitized solar cell performance by mechanical compression

    NASA Astrophysics Data System (ADS)

    Meen, Teen Hang; Tsai, Jenn Kai; Tu, Yu Shin; Wu, Tian Chiuan; Hsu, Wen Dung; Chang, Shoou-Jinn

    2014-09-01

    In this study, the P25 titanium dioxide (TiO2) nanoparticle (NP) thin film was coated on the fluorine-doped tin oxide (FTO) glass substrate by a doctor blade method. The film then compressed mechanically to be the photoanode of dye-sensitized solar cells (DSSCs). Various compression pressures on TiO2 NP film were tested to optimize the performance of DSSCs. The mechanical compression reduces TiO2 inter-particle distance improving the electron transport efficiency. The UV-vis spectrophotometer and electrochemical impedance spectroscopy (EIS) were employed to quantify the light-harvesting efficiency and the charge transport impedance at various interfaces in DSSC, respectively. The incident photon-to-current conversion efficiency was also monitored. The results show that when the DSSC fabricated by the TiO2 NP thin film compressed at pressure of 279 kg/cm2, the minimum resistance of 9.38 Ω at dye/TiO2 NP/electrolyte interfaces, the maximum short-circuit photocurrent density of 15.11 mA/cm2, and the photoelectric conversion efficiency of 5.94% were observed. Compared to the DSSC fabricated by the non-compression of TiO2 NP thin film, the overall conversion efficiency is improved over 19.5%. The study proves that under suitable compression pressure the performance of DSSC can be optimized.

  10. Optimization of the dye-sensitized solar cell performance by mechanical compression

    PubMed Central

    2014-01-01

    In this study, the P25 titanium dioxide (TiO2) nanoparticle (NP) thin film was coated on the fluorine-doped tin oxide (FTO) glass substrate by a doctor blade method. The film then compressed mechanically to be the photoanode of dye-sensitized solar cells (DSSCs). Various compression pressures on TiO2 NP film were tested to optimize the performance of DSSCs. The mechanical compression reduces TiO2 inter-particle distance improving the electron transport efficiency. The UV–vis spectrophotometer and electrochemical impedance spectroscopy (EIS) were employed to quantify the light-harvesting efficiency and the charge transport impedance at various interfaces in DSSC, respectively. The incident photon-to-current conversion efficiency was also monitored. The results show that when the DSSC fabricated by the TiO2 NP thin film compressed at pressure of 279 kg/cm2, the minimum resistance of 9.38 Ω at dye/TiO2 NP/electrolyte interfaces, the maximum short-circuit photocurrent density of 15.11 mA/cm2, and the photoelectric conversion efficiency of 5.94% were observed. Compared to the DSSC fabricated by the non-compression of TiO2 NP thin film, the overall conversion efficiency is improved over 19.5%. The study proves that under suitable compression pressure the performance of DSSC can be optimized. PMID:25276109

  11. Optimization of the dye-sensitized solar cell performance by mechanical compression.

    PubMed

    Meen, Teen Hang; Tsai, Jenn Kai; Tu, Yu Shin; Wu, Tian Chiuan; Hsu, Wen Dung; Chang, Shoou-Jinn

    2014-01-01

    In this study, the P25 titanium dioxide (TiO2) nanoparticle (NP) thin film was coated on the fluorine-doped tin oxide (FTO) glass substrate by a doctor blade method. The film then compressed mechanically to be the photoanode of dye-sensitized solar cells (DSSCs). Various compression pressures on TiO2 NP film were tested to optimize the performance of DSSCs. The mechanical compression reduces TiO2 inter-particle distance improving the electron transport efficiency. The UV-vis spectrophotometer and electrochemical impedance spectroscopy (EIS) were employed to quantify the light-harvesting efficiency and the charge transport impedance at various interfaces in DSSC, respectively. The incident photon-to-current conversion efficiency was also monitored. The results show that when the DSSC fabricated by the TiO2 NP thin film compressed at pressure of 279 kg/cm(2), the minimum resistance of 9.38 Ω at dye/TiO2 NP/electrolyte interfaces, the maximum short-circuit photocurrent density of 15.11 mA/cm(2), and the photoelectric conversion efficiency of 5.94% were observed. Compared to the DSSC fabricated by the non-compression of TiO2 NP thin film, the overall conversion efficiency is improved over 19.5%. The study proves that under suitable compression pressure the performance of DSSC can be optimized. PMID:25276109

  12. Compression failure mechanisms of single-ply, unidirectional, carbon-fiber composites

    NASA Technical Reports Server (NTRS)

    Ha, Jong-Bae; Nairn, John A.

    1992-01-01

    A single-ply composite compression test was used to study compression failure mechanisms as a function of fiber type, matrix type, and interfacial strength. Composites made with low- and intermediate-modulus fibers (Hercules AS4 and IM7) in either an epoxy (Hercules 3501-6) or a thermoplastic (ULTEM and LARC-TPI) matrix failed by kink banding and out-of-plane slip. The failures proceeded by rapid and catastrophic damage propagation across the specimen width. Composites made with high-modulus fibers (Hercules HMS4/3501-6) had a much lower compression strength. Their failures were characterized by kink banding and longitudinal splitting. The damage propagated slowly across the specimen width. Composites made with fibers treated to give low interfacial strength had low compression strength. These composites typically failed near the specimen ends and had long kink bands.

  13. Variability and anisotropy of mechanical behavior of cortical bone in tension and compression.

    PubMed

    Li, Simin; Demirci, Emrah; Silberschmidt, Vadim V

    2013-05-01

    The mechanical properties of cortical bone vary not only from bone to bone; they demonstrate a spatial viability even within the same bone due to its changing microstructure. They also depend considerably on different loading modes and orientations. To understand the variability and anisotropic mechanical behavior of a cortical bone tissue, specimens cut from four anatomical quadrants of bovine femurs were investigated both in tension and compression tests. The obtained experimental results revealed a highly anisotropic mechanical behavior, depending also on the loading mode (tension and compression). A compressive longitudinal loading regime resulted in the best load-bearing capacity for cortical bone, while tensile transverse loading provided significantly poorer results. The distinctive stress-strain curves obtained for tension and compression demonstrated various damage mechanisms associated with different loading modes. The variability of mechanical properties for different cortices was evaluated with two-way ANOVA analyses. Statistical significances were found among different quadrants for the Young's modulus. The results of microstructure analysis of the entire transverse cross section of a cortical bone also confirmed variations of volume fractions of constituents at microscopic level between anatomic quadrants: microstructure of the anterior quadrant was dominated by plexiform bone, whereas secondary osteons were prominent in the posterior quadrant. The effective Young's modulus predicted using the modified Voigt-Reuss-Hill averaging scheme accurately reproduced our experimental results, corroborating additionally a strong effect of random and heterogeneous microstructure on variation of mechanical properties in cortical bone. PMID:23563047

  14. Chest tube insertion

    MedlinePlus

    Chest drainage tube insertion; Insertion of tube into chest; Tube thoracostomy; Pericardial drain ... When your chest tube is inserted, you will lie on your side or sit partly upright, with one arm over your ...

  15. Chest tube insertion

    MedlinePlus

    ... leaks from inside the lung into the chest ( pneumothorax ) Fluid buildup in the chest (called a pleural ... on the reason a chest tube is inserted. Pneumothorax usually improves, but sometimes needs minimally invasive surgery. ...

  16. Inelastic deformation mechanisms in SCS-6/Ti 15-3 MMC lamina under compression

    NASA Technical Reports Server (NTRS)

    Newaz, Golam M.; Majumdar, Bhaskar S.

    1993-01-01

    An investigation was undertaken to study the inelastic deformation mechanisms in (0)(sub 8) and (90)(sub 8) Ti 15-3/SCS-6 lamina subjected to pure compression. Monotonic tests were conducted at room temperature (RT), 538 C and 650 C. Results indicate that mechanical response and deformation characteristics were different in monotonic tension and compression loading whereas some of those differences could be attributed to residual stress effects. There were other differences because of changes in damage and failure modes. The inelastic deformation in the (0)(sub 8) lamina under compression was controlled primarily by matrix plasticity, although some evidence of fiber-matrix debonding was observed. Failure of the specimen in compression was due to fiber buckling in a macroscopic shear zone (the failure plane). The inelastic deformation mechanisms under compression in (90)(sub 8) lamina were controlled by radial fiber fracture, matrix plasticity, and fiber-matrix debonding. The radial fiber fracture was a new damage mode observed for MMC's. Constitutive response was predicted for both the (0)(sub 8) and (90)(sub 8) laminae, using AGLPLY, METCAN, and Battelle's Unit Cell FEA model. Results from the analyses were encouraging.

  17. Mechanically induced structural changes during dynamic compression of engineered cartilaginous constructs can potentially explain increases in bulk mechanical properties

    PubMed Central

    Nagel, Thomas; Kelly, Daniel J.

    2012-01-01

    Several studies on chondrocyte-seeded hydrogels in bioreactor culture report increased mechanical properties of mechanically loaded constructs compared with unloaded free swelling controls despite no significant differences in biochemical composition. One possible explanation is that changes in the collagen architecture of dynamically compressed constructs lead to improved mechanical properties. Collagen molecules are incorporated locally into the extracellular matrix with individual stress-free configurations and orientations. In this study, we computationally investigated possible influences of loading on the collagen architecture in chondrocyte-seeded hydrogels and their resulting mechanical properties. Both the collagen orientation and its stress-free configuration were hypothesized to depend on the local mechanical environment. Reorientation of the collagen network alone in response to dynamic compression leads to a prediction of constructs with lower compressive properties. In contrast, remodelling of the stress-free configuration of the collagen fibres was predicted to result in a more compacted tissue with higher swelling pressures and an altered pre-stressed state within the collagen network. Combining both mechanisms resulted in predictions of construct geometry and mechanical properties in agreement with experimental observations. This study provides support for the hypothesis that structural changes to the collagen network contribute to the enhanced mechanical properties of cartilaginous tissues engineered in bioreactors. PMID:21900321

  18. A variational principle for compressible fluid mechanics: Discussion of the multi-dimensional theory

    NASA Technical Reports Server (NTRS)

    Prozan, R. J.

    1982-01-01

    The variational principle for compressible fluid mechanics previously introduced is extended to two dimensional flow. The analysis is stable, exactly conservative, adaptable to coarse or fine grids, and very fast. Solutions for two dimensional problems are included. The excellent behavior and results lend further credence to the variational concept and its applicability to the numerical analysis of complex flow fields.

  19. Determining Tension-Compression Nonlinear Mechanical Properties of Articular Cartilage from Indentation Testing.

    PubMed

    Chen, Xingyu; Zhou, Yilu; Wang, Liyun; Santare, Michael H; Wan, Leo Q; Lu, X Lucas

    2016-04-01

    The indentation test is widely used to determine the in situ biomechanical properties of articular cartilage. The mechanical parameters estimated from the test depend on the constitutive model adopted to analyze the data. Similar to most connective tissues, the solid matrix of cartilage displays different mechanical properties under tension and compression, termed tension-compression nonlinearity (TCN). In this study, cartilage was modeled as a porous elastic material with either a conewise linear elastic matrix with cubic symmetry or a solid matrix reinforced by a continuous fiber distribution. Both models are commonly used to describe the TCN of cartilage. The roles of each mechanical property in determining the indentation response of cartilage were identified by finite element simulation. Under constant loading, the equilibrium deformation of cartilage is mainly dependent on the compressive modulus, while the initial transient creep behavior is largely regulated by the tensile stiffness. More importantly, altering the permeability does not change the shape of the indentation creep curves, but introduces a parallel shift along the horizontal direction on a logarithmic time scale. Based on these findings, a highly efficient curve-fitting algorithm was designed, which can uniquely determine the three major mechanical properties of cartilage (compressive modulus, tensile modulus, and permeability) from a single indentation test. The new technique was tested on adult bovine knee cartilage and compared with results from the classic biphasic linear elastic curve-fitting program. PMID:26240062

  20. Thermal and mechanical properties of compression-molded pMDI-reinforced PCL/gluten composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polycaprolactone (PCL) and vital wheat gluten or wheat flour composites were prepared and compatibilized with polymeric diphenylmethane diisocyanate (pMDI) by blending and compression-molding. The thermo-mechanical properties of the composites were determined by thermogravimetric analysis (TGA), di...

  1. Coaxial carbon@boron nitride nanotube arrays with enhanced thermal stability and compressive mechanical properties.

    PubMed

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Huang, Jingfeng; Tan, Dunlin; Zhang, Bowei; Teo, Edwin Hang Tong; Tok, Alfred Iing Yoong

    2016-06-01

    Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability. CNT arrays are grown using a commercially available thermal chemical vapor deposition (TCVD) technique and an outer BNNT with a wall thickness up to 1.37 nm is introduced by a post-growth TCVD treatment. Importantly, compared to the as-grown CNT arrays which deform almost plastically upon compression, the coaxial C@BNNT arrays exhibit an impressive ∼4-fold increase in compressive strength with nearly full recovery after the first compression cycle at a 50% strain (76% recovery maintained after 10 cycles), as well as a significantly high and persistent energy dissipation ratio (∼60% at a 50% strain after 100 cycles), attributed to the synergistic effect between the CNT and outer BNNT. Additionally, the as-prepared C@BNNT arrays show an improved structural stability in air at elevated temperatures, attributing to the outstanding thermal stability of the outer BNNT. This work provides new insights into tailoring the mechanical and thermal behaviours of arbitrary CNT arrays which enables a broader range of applications. PMID:27227818

  2. Research of mechanics of the compact bone microvolume and porous ceramics under uniaxial compression

    SciTech Connect

    Kolmakova, T. V. Buyakova, S. P. Kul’kov, S. N.

    2015-11-17

    The research results of the mechanics are presented and the effective mechanical characteristics under uniaxial compression of the simulative microvolume of the compact bone are defined subject to the direction of the collagen-mineral fibers, porosity and mineral content. The experimental studies of the mechanics are performed and the effective mechanical characteristics of the produced porous zirconium oxide ceramics are defined. The recommendations are developed on the selection of the ceramic samples designed to replace the fragment of the compact bone of a definite structure and mineral content.

  3. Long-term mechanical behaviour of skeletal muscle tissue in semi-confined compression experiments.

    PubMed

    Böl, Markus; Leichsenring, Kay; Ernst, Michael; Ehret, Alexander E

    2016-10-01

    In this study, porcine skeletal muscle tissue was tested until 112 hours post mortem using a semi-confined compression device that induces fascicles to enter one of the states of compression (mode I), tension (mode II), or constant length (mode III). Based on the authors׳ previous studies (Böl et al., 2014, 2015a), the anisotropic mechanical behaviour of the tissue was analysed, with a special focus on the testing time post mortem. The results suggest that the tissue exhibits significant anisotropic behaviour during the first hours of post mortem but that this anisotropy becomes insignificant at later time points. Interestingly, the compressibility of the tissue is more or less unaffected by the testing time. These results are discussed especially with respect to tissue microstructure. PMID:27367943

  4. Mechanical Modeling of Foods Including Fracture and Simulation of Food Compression

    NASA Astrophysics Data System (ADS)

    Morimoto, Masamichi; Mizunuma, Hiroshi; Sonomura, Mitsuhiro; Kohyama, Kaoru; Ogoshi, Hiro

    2008-07-01

    The purposes of this research are to simulate the swallowing of foods, and to investigate the relationship between the rheological properties of foods and the swallowing. Here we proposed the mechanical modeling of foods, and simulated the compression test using the finite element method. A linear plasticity model was applied as the rheological model of the foods, and two types of computational elements were used to simulate the fracture behavior. The compression tests with a wedged plunger were simulated for tofu, banana, and biscuit, and were compared with the experimental results. Other than the homogeneous food model, the simulations were conducted for the multi-layer models. Reasonable agreements on the behaviors of compression and fracture were obtained between the simulations and the experiments including the reaction forces on the plunger.

  5. Suppression mechanism of Kelvin-Helmholtz instability in compressible fluid flows

    NASA Astrophysics Data System (ADS)

    Karimi, Mona; Girimaji, Sharath S.

    2016-04-01

    The transformative influence of compressibility on the Kelvin-Helmholtz instability (KHI) at the interface between two fluid streams of different velocities is explicated. When the velocity difference is small (subsonic), shear effects dominate the interface flow dynamics causing monotonic roll-up of vorticity and mixing between the two streams leading to the KHI. We find that at supersonic speed differentials, compressibility forces the dominance of dilatational (acoustic) rather than shear dynamics at the interface. Within this dilatational interface layer, traveling pressure waves cause the velocity perturbations to become oscillatory. We demonstrate that the oscillatory fluid motion reverses vortex roll-up and segregates the two streams leading to KHI suppression. Analysis and illustrations of the compressibility-induced suppression mechanism are presented.

  6. Volar/dorsal compressive mechanical behavior of the transverse carpal ligament.

    PubMed

    Main, Erin K; Goetz, Jessica E; Baer, Thomas E; Klocke, Noelle F; Brown, Thomas D

    2012-04-30

    Mechanical insult to the median nerve caused by contact with the digital flexor tendons and/or carpal tunnel boundaries may contribute to the development of carpal tunnel syndrome. Since the transverse carpal ligament (TCL) comprises the volar boundary of the carpal tunnel, its mechanics in part govern the potential insult to the median nerve. Using unconfined compression testing in combination with a finite element-based optimization process, nominal stiffness measurements and first-order Ogden hyperelastic material coefficients (μ and α ) were determined to describe the volar/dorsal compressive behavior of the TCL. Five different locations on the TCL were tested, three of which were deep to the origins of the thenar and hypothenar muscles. The average (± standard deviation) low-strain and high-strain TCL stiffness values in compression sites outside the muscle attachment region were 3.6 N/mm (±2.7) and 28.0 N/mm (±20.2), respectively. The average stiffness values at compression sites with muscle attachments were notably lower, with low-strain and high-strain stiffness values of 1.2 N/mm (±0.5) and 9.7 N/mm (±4.8), respectively. The average Ogden coefficients for the muscle attachment region were 51.6 kPa (±16.5) for μ and 16.5 (±2.0) for α, while coefficients for the non-muscle attachment region were 117.8 kPa (±86.8) for μ and 17.2 (±1.6) for α. These TCL compressive mechanical properties can help inprove computational models, which can be used to provide insight into the mechanisms of median nerve injury leading to the onset of carpal tunnel syndrome symptoms. PMID:22381735

  7. Esophageal pressure as an estimate of average pleural pressure with lung or chest distortion in rats.

    PubMed

    Pecchiari, Matteo; Loring, Stephen H; D'Angelo, Edgardo

    2013-04-01

    Pressure-volume curves of the lungs and chest wall require knowledge of an effective 'average' pleural pressure (Pplav), and are usually estimated using esophageal pressure as Ples-V and Pwes-V curves. Such estimates could be misleading when Ppl becomes spatially non-uniform with lung lavage or shape distortion of the chest. We therefore measured Ples-V and Pwes-V curves in conditions causing spatial non-uniformity of Ppl in rats. Ples-V curves of normal lungs were unchanged by chest removal. Lung lavage depressed PLes-V but not Pwes-V curves to lower volumes, and chest removal after lavage increased volumes at PL≥15cmH2O by relieving distortion of the mechanically heterogeneous lungs. Chest wall distortion by ribcage compression or abdominal distension depressed Pwes-V curves and Ples-V curves of normal lungs only at Pl≥3cmH2O. In conclusion, Pes reflects Pplav with normal and mechanically heterogeneous lungs. With chest wall distortion and dependent deformation of the normal lung, changes of Ples-V curves are qualitatively consistent with greater work of inflation. PMID:23416404

  8. Coaxial carbon@boron nitride nanotube arrays with enhanced thermal stability and compressive mechanical properties

    NASA Astrophysics Data System (ADS)

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Huang, Jingfeng; Tan, Dunlin; Zhang, Bowei; Teo, Edwin Hang Tong; Tok, Alfred Iing Yoong

    2016-05-01

    Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability. CNT arrays are grown using a commercially available thermal chemical vapor deposition (TCVD) technique and an outer BNNT with a wall thickness up to 1.37 nm is introduced by a post-growth TCVD treatment. Importantly, compared to the as-grown CNT arrays which deform almost plastically upon compression, the coaxial C@BNNT arrays exhibit an impressive ~4-fold increase in compressive strength with nearly full recovery after the first compression cycle at a 50% strain (76% recovery maintained after 10 cycles), as well as a significantly high and persistent energy dissipation ratio (~60% at a 50% strain after 100 cycles), attributed to the synergistic effect between the CNT and outer BNNT. Additionally, the as-prepared C@BNNT arrays show an improved structural stability in air at elevated temperatures, attributing to the outstanding thermal stability of the outer BNNT. This work provides new insights into tailoring the mechanical and thermal behaviours of arbitrary CNT arrays which enables a broader range of applications.Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability

  9. High-frequency oscillation of the airway and chest wall.

    PubMed

    Fink, James B; Mahlmeister, Michael J

    2002-07-01

    High-frequency oscillation (HFO), applied to either the airway or chest wall, has been associated with changes in sputum attributes and clearance. The evolution of evidence, both in vitro and in vivo, supporting the use of HFO is reviewed. Devices that apply HFO to the airway range from the relatively simple mechanical Flutter and Acapella devices to the more complex Percussionaire Intrapercussive Ventilators. and the Hayek Oscillator are designed to provide high-frequency chest wall compression. Operation and use of these devices are described with examples of differentiation of device types by characterization of flows, and airway and esophageal pressures. Although HFO devices span a broad range of costs, they provide a reasonable therapeutic option to support secretion clearance for patients with cystic fibrosis. PMID:12088550

  10. On the Study of Lifting Mechanism of a Soft Porous Media under Fast Compression

    NASA Astrophysics Data System (ADS)

    Wu, Qianhong; Santhanam, S.; Nathan, R.; Vucbmss Team

    2015-11-01

    Fluid flow in a soft porous media under fast compressions is widely observed in biological systems and industrial applications. Despite of much progress, it remains unclear for the lifting mechanisms of the porous media due to the lack of complete experimental verifications of theoretical models. We report herein a unique approach to treat the limitation. The permeability of a synthetic fibrous porous media as a function of its compression was first measured. The material was then employed in a dynamic compression experiment using a porous-walled cylinder piston apparatus. The obtained transient compression of the porous media and the aforementioned permeability data were applied in different theoretical models for the pore pressure generation, which conclusively proved the validity of the consolidation theory developed by Wu et al. (JFM, 542, 281, 2005). Furthermore, the solid phase lifting force was separated from the total reaction force and was characterized by a new viscoelastic model, containing a nonlinear spring in conjunction with a linear viscoelastic Generalized Maxwell mechanical module. Excellent agreement was obtained between the experiment and the theory. Thus, the lifting forces from both the fluid and the solid were determined. This project is supported by NSF Grant 1511096.

  11. Kronecker compressive sensing-based mechanism with fully independent sampling dimensions for hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Zhao, Rongqiang; Wang, Qiang; Shen, Yi

    2015-11-01

    We propose a new approach for Kronecker compressive sensing of hyperspectral (HS) images, including the imaging mechanism and the corresponding reconstruction method. The proposed mechanism is able to compress the data of all dimensions when sampling, which can be achieved by three fully independent sampling devices. As a result, the mechanism greatly reduces the control points and memory requirement. In addition, we can also select the suitable sparsifying bases and generate the corresponding optimized sensing matrices or change the distribution of sampling ratio for each dimension independently according to different HS images. As the cooperation of the mechanism, we combine the sparsity model and low multilinear-rank model to develop a reconstruction method. Analysis shows that our reconstruction method has a lower computational complexity than the traditional methods based on sparsity model. Simulations verify that the HS images can be reconstructed successfully with very few measurements. In summary, the proposed approach can reduce the complexity and improve the practicability for HS image compressive sensing.

  12. Mechanical and Numerical Analysis Concerning Compressive Properties of Tin-Lead Open-Cell Foams

    NASA Astrophysics Data System (ADS)

    Belhadj, Abd-Elmouneïm; Gavrus, Adinel; Bernard, Fabrice; Azzaz, Mohammed

    2015-10-01

    The design of new or innovative materials has to meet two essential criteria: increased mechanical performance and minimization of the mass. This dual requirement leads to interest in the study of various classes of metallic foams. The actual research is focused on open-cell Tin-Lead foams manufactured by replication process using NaCl preform. A mechanical press equipped with a load cell and a local extensometer with a controlled deformation rate is used. Experimental tests were carried out in order to study the influences of both the cell size and of the relative density on the mechanical behavior during a compression deformation and to analyze the obtained properties variation within a new framework. This study has three main sections which start with the manufacturing description and mechanical characterization of the proposed metallic foams followed by the understanding and modeling of their response to a compression load via a Gibson-Ashby model, a Féret law, a proposed simple Avrami model, and a generalized Avrami model. Finally, an exposition of a numerical simulation analyzing the compression of the Sn-Pb foams concerning the variation of the relative densities with respect to the plastic strain is proposed.

  13. Chest pain evaluation in the emergency department.

    PubMed

    Foy, Andrew J; Filippone, Lisa

    2015-07-01

    Chest pain is a common complaint in the emergency department. Recognition of chest pain symptoms and electrocardiographic changes consistent with acute coronary syndrome (ACS) can lead to prompt initiation of goal-directed therapy. Cardiac troponin testing confirms the diagnosis of acute myocardial infarction, but does not reveal the mechanism of injury. When patients with chest pain rule out for ACS the use of advanced, noninvasive testing has not been found to be associated with better patient outcomes. PMID:26042885

  14. Failure mechanisms in laminated carbon/carbon composites under biaxial compression

    SciTech Connect

    Grape, J.A.; Gupta, V.

    1995-07-01

    The failure mechanisms of 2D carbon/carbon (C/C) woven laminates have been determined under inplane biaxial compression loads, and the associated failure envelopes that account for the effect of matrix-type and loading directions were also obtained. The failure was in the form of micro-kinking of fiber bundles, interspersed with localized interply delaminations to form an overall shear fault. The shear fault was aligned with the major axis of loading except at above 75% of balanced biaxial compressive stress where failure occurred along both axes. Although the biaxial strength varied significantly with the ratio of in-plane principal stresses, R, there was no variation in the local failure mechanisms. Accordingly, it was found that the samples fail upon achieving a critical strain along the primary axis of loading.

  15. Chest X-Ray

    MedlinePlus Videos and Cool Tools

    ... Prostate Ultrasound Video: IMRT Video: Chest CT Video:Thyroid Ultrasound Video: Pediatric MRI Radiology and You About ... Prostate Ultrasound Video: IMRT Video: Chest CT Video:Thyroid Ultrasound Video: Pediatric MRI Radiology and You About ...

  16. Measuring the compressive viscoelastic mechanical properties of human cervical tissue using indentation.

    PubMed

    Yao, Wang; Yoshida, Kyoko; Fernandez, Michael; Vink, Joy; Wapner, Ronald J; Ananth, Cande V; Oyen, Michelle L; Myers, Kristin M

    2014-06-01

    The human cervix is an important mechanical barrier in pregnancy which must withstand the compressive and tensile forces generated from the growing fetus. Premature cervical shortening resulting from premature cervical remodeling and alterations of cervical material properties are known to increase a woman׳s risk of preterm birth (PTB). To understand the mechanical role of the cervix during pregnancy and to potentially develop indentation techniques for in vivo diagnostics to identify women who are at risk for premature cervical remodeling and thus preterm birth, we developed a spherical indentation technique to measure the time-dependent material properties of human cervical tissue taken from patients undergoing hysterectomy. In this study we present an inverse finite element analysis (IFEA) that optimizes material parameters of a viscoelastic material model to fit the stress-relaxation response of excised tissue slices to spherical indentation. Here we detail our IFEA methodology, report compressive viscoelastic material parameters for cervical tissue slices from nonpregnant (NP) and pregnant (PG) hysterectomy patients, and report slice-by-slice data for whole cervical tissue specimens. The material parameters reported here for human cervical tissue can be used to model the compressive time-dependent behavior of the tissue within a small strain regime of 25%. PMID:24548950

  17. A mechanism responsible for reducing compression strength of through-the-thickness reinforced composite material

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.

    1992-01-01

    A study was conducted to identify one of the mechanisms that contributes to the reduced compression strength of composite materials with through-the-thickness (TTT) reinforcements. In this study a series of thick (0/90) laminates with stitched and integrally woven TTT reinforcements were fabricated and statically tested. In both the stitching and weaving process a surface loop of TTT reinforcement yarn is created between successive TTT penetrations. It was shown that the surface loop of the TTT reinforcement 'kinked' the in-plane fibers in such a manner that they were made ineffective in carrying compressive load. The improvement in strength by removal of the surface loop and 'kinked' in-plane fibers was between 7 and 35 percent.

  18. New compression mechanism in penile-scrotal lymphedema and sexual rehabilitation

    PubMed Central

    de Godoy, Jose Maria Pereira; Facio, Fernando Nestor; de Carvalho, Eleni Cássia Matias; Godoy, Maria de Fatima Guerreiro

    2014-01-01

    The objective of this study is to describe a new compression mechanism in the treatment of lymphedema of the penis and scrotum and the ensuing sexual rehabilitation. The patient, a 58-year-old man, had edema of the penile and scrotal region as a result of surgery of the pancreas and spleen and chemotherapy. The patient complained of pain, discomfort, and difficulties to walk and urinate. A clinical diagnosis of lymphedema of the penis and scrotum was reached. Treatment involved the continuous use of a cotton-polyester compression garment for the region together with thorough hygiene skin care. The swelling reduced significantly within a week to almost a normal aspect which was accompanied by clinical improvements of the symptoms. The reduction in penile edema allowed sexual rehabilitation even though erectile dysfunction required the use of a specific medication (sildenafil). In conclusion, simple and low-cost options can improve lymphedema of the penis and scrotum and allow sexual rehabilitation. PMID:24669133

  19. Chest pain in children.

    PubMed Central

    Leung, A. K.; Robson, W. L.; Cho, H.

    1996-01-01

    Chest pain is usually a benign symptom in children. The most common identifiable causes are musculoskeletal. Often, no cause can be identified. Cardiac disorders are uncommon causes of chest pain children. Most causes can be diagnosed from history and physical examination. Treatment should be directed at the underlying cause. For idiopathic chest pain, reassurance and regular follow-up examinations are important. PMID:8704491

  20. Chest x-ray

    MedlinePlus

    Chest radiography; Serial chest x-ray; X-ray - chest ... You stand in front of the x-ray machine. You will be told to hold your breath when the x-ray is taken. Two images are usually taken. You will ...

  1. American College of Chest Physicians

    MedlinePlus

    ... of Certification (MOC) CHEST GAIN NSCLC CHEST SEEK Innovation, Simulation, and Training Center Professional Representative Education Program ( ... of Certification (MOC) CHEST GAIN NSCLC CHEST SEEK Innovation, Simulation, and Training Center Professional Representative Education Program ( ...

  2. Determination of the mechanical properties of solid and cellular polymeric dosage forms by diametral compression.

    PubMed

    Blaesi, Aron H; Saka, Nannaji

    2016-07-25

    At present, the immediate-release solid dosage forms, such as the oral tablets and capsules, are granular solids. They release drug rapidly and have adequate mechanical properties, but their manufacture is fraught with difficulties inherent in processing particulate matter. Such difficulties, however, could be overcome by liquid-based processing. Therefore, we have recently introduced polymeric cellular (i.e., highly porous) dosage forms prepared from a melt process. Experiments have shown that upon immersion in a dissolution medium, the cellular dosage forms with polyethylene glycol (PEG) as excipient and with predominantly open-cell topology disintegrate by exfoliation, thus enabling rapid drug release. If the volume fraction of voids of the open-cell structures is too large, however, their mechanical strength is adversely affected. At present, the common method for determining the tensile strength of brittle, solid dosage forms (such as select granular forms) is the diametral compression test. In this study, the theory of diametral compression is first refined to demonstrate that the relevant mechanical properties of ductile and cellular solids (i.e., the elastic modulus and the yield strength) can also be extracted from this test. Diametral compression experiments are then conducted on PEG-based solid and cellular dosage forms. It is found that the elastic modulus and yield strength of the open-cell structures are about an order of magnitude smaller than those of the non-porous solids, but still are substantially greater than the stiffness and strength requirements for handling the dosage forms manually. This work thus demonstrates that melt-processed polymeric cellular dosage forms that release drug rapidly can be designed and manufactured to have adequate mechanical properties. PMID:27178343

  3. Mechanical and thermal hyperalgesia and ectopic neuronal discharge after chronic compression of dorsal root ganglia.

    PubMed

    Song, X J; Hu, S J; Greenquist, K W; Zhang, J M; LaMotte, R H

    1999-12-01

    Chronic compression of the dorsal root ganglion (CCD) was produced in adult rats by implanting a stainless steel rod unilaterally into the intervertebral foramen, one rod at L(4) and another at L(5). Two additional groups of rats received either a sham surgery or an acute injury consisting of a transient compression of the ganglion. Withdrawal of the hindpaw was used as evidence of a nocifensive response to mechanical and thermal stimulation of the plantar surface. In addition, extracellular electrophysiological recordings of spontaneous discharges were obtained from dorsal root fibers of formerly compressed ganglia using an in vitro nerve-DRG-dorsal root preparation. The mean threshold force of punctate indentation and the mean threshold temperature of heating required to elicit a 50% incidence of foot withdrawal ipsilateral to the CCD were significantly lower than preoperative values throughout the 35 days of postoperative testing. The number of foot withdrawals ipsilateral to the CCD during a 20-min contact with a temperature-controlled floor was significantly increased over preoperative values throughout postoperative testing when the floor was 4 degrees C (hyperalgesia) and, to a lesser extent, when it was 30 degrees C (spontaneous pain). Stroking the foot with a cotton wisp never elicited a reflex withdrawal before surgery but did so in most rats tested ipsilateral to the CCD during the first 2 postoperative weeks. In contrast, the CCD produced no changes in responses to mechanical or thermal stimuli on the contralateral foot. The sham operation and acute injury produced no change in behavior other than slight, mechanical hyperalgesia for approximately 1 day, ipsilateral to the acute injury. Ectopic spontaneous discharges generated within the chronically compressed ganglion and, occurring in the absence of blood-borne chemicals and without an intact sympathetic nervous system, were recorded from neurons with intact, conducting, myelinated or unmyelinated

  4. Mechanical response of porcine skin under compression from low to high strain rates

    NASA Astrophysics Data System (ADS)

    Bo, Chiara; Butler, Ben; Williams, Alun; Brown, Katherine; Proud, William

    2013-06-01

    Uniaxial compression experiments were performed on fresh porcine skin samples at different strain rates to study the stress-strain response. Low strain rate experiments were performed with an Instron 5566, while high strain rates were achieved using a Split Hopkinson Pressure Bar system. Magnesium bars and semiconductor strain gauges were used respectively to maximize the signal transmission from porcine skin to the output bar and to allow the signal measurement. Skin samples were harvested from different area of the animal to investigate the heterogeneity of such material. The experimental results showed that the mechanical response of skin in compression is strongly dependent on the strain rate of loading and on the location from which the samples were collected. Specimens collected from the rump showed a stiffer response compared to samples harvested from the thigh. Finally, a histological analysis of the samples post compression was carried out to examine the extent of tissue damage as a function of strain rate. This work is supported by the Atomic Weapons Establishment, UK and The Royal British Legion Centre for Blast Injury Studies at Imperial College London, UK.

  5. Compressive mechanical properties of Sm123 bulk superconductor at liquid nitrogen temperature

    NASA Astrophysics Data System (ADS)

    Murakami, A.; Katagiri, K.; Kan, R.; Miyata, H.; Shoji, Y.; Noto, K.; Iwamoto, A.; Mito, T.

    2005-10-01

    In order to investigate the compressive mechanical properties of a single-grain Sm123 bulk superconductor at cryogenic temperature, compressive tests at liquid nitrogen temperature on small specimens with the dimensions of 3 × 3 × 8 mm 3 cut from the bulk with 45 mm in diameter and 15 mm in thickness were carried out. Due to the closure of pre-existing micro-cracks perpendicular to the c-axis, the average Young’s modulus in the c-axis, 93 GPa, was lower than that in the direction perpendicular to the c-axis, 150 GPa. While the former was higher than the value at room temperature (RT), 75 GPa, the latter was slightly lower than that, 165 GPa. The compressive strength in the c-axis, 466 MPa, was higher than that in the direction perpendicular to the c-axis, 368 MPa. This anisotropy is also ascribed to the pre-existing micro-cracks associated with the fracture mode. Both the former and the latter were higher than the values at RT, 350 and 335 MPa, respectively. Most of the specimens loaded in perpendicular to the c-axis fractured along the plane perpendicular to the c-axis into a few pieces. The specimen loaded in the c-axis fractured into many small fragments, although the specimen with extraordinarily low strength fractured in a similar mode as mentioned above.

  6. Mechanical behavior and microstructure of compressed Ti foams synthesized via freeze casting.

    PubMed

    Jenei, Péter; Choi, Hyelim; Tóth, Adrián; Choe, Heeman; Gubicza, Jenő

    2016-10-01

    Pure Ti and Ti-5%W foams were prepared via freeze casting. The porosity and grain size of both the materials were 32-33% and 15-17µm, respectively. The mechanical behavior of the foams was investigated by uniaxial compression up to a plastic strain of ~0.26. The Young׳s moduli of both foams were ~23GPa, which was in good agreement with the value expected from their porosity. The Young׳s moduli of the foams were similar to the elastic modulus of cortical bones, thereby eliminating the osteoporosis-causing stress-shielding effect. The addition of W increased the yield strength from ~196MPa to ~235MPa. The microstructure evolution in the grains during compression was studied using electron backscatter diffraction (EBSD) and X-ray line profile analysis (XLPA). After compression up to a plastic strain of ~0.26, the average dislocation densities increased to ~3.4×10(14)m(-2) and ~5.9×10(14)m(-2) in the Ti and Ti-W foams, respectively. The higher dislocation density in the Ti-W foam can be attributed to the pinning effect of the solute tungsten atoms on dislocations. The experimentally measured yield strength was in good agreement with the strength calculated from the dislocation density and porosity. This study demonstrated that the addition of W to Ti foam is beneficial for biomedical applications, because the compressive yield strength increased while its Young׳s modulus remained similar to that of cortical bones. PMID:27469602

  7. Influence of Tension-Compression Asymmetry on the Mechanical Behavior of AZ31B Magnesium Alloy Sheets in Bending

    NASA Astrophysics Data System (ADS)

    Zhou, Ping; Beeh, Elmar; Friedrich, Horst E.

    2016-03-01

    Magnesium alloys are promising materials for lightweight design in the automotive industry due to their high strength-to-mass ratio. This study aims to study the influence of tension-compression asymmetry on the radius of curvature and energy absorption capacity of AZ31B-O magnesium alloy sheets in bending. The mechanical properties were characterized using tension, compression, and three-point bending tests. The material exhibits significant tension-compression asymmetry in terms of strength and strain hardening rate due to extension twinning in compression. The compressive yield strength is much lower than the tensile yield strength, while the strain hardening rate is much higher in compression. Furthermore, the tension-compression asymmetry in terms of r value (Lankford value) was also observed. The r value in tension is much higher than that in compression. The bending results indicate that the AZ31B-O sheet can outperform steel and aluminum sheets in terms of specific energy absorption in bending mainly due to its low density. In addition, the AZ31B-O sheet was deformed with a larger radius of curvature than the steel and aluminum sheets, which brings a benefit to energy absorption capacity. Finally, finite element simulation for three-point bending was performed using LS-DYNA and the results confirmed that the larger radius of curvature of a magnesium specimen is mainly attributed to the high strain hardening rate in compression.

  8. Theoretical insight into the sensitive mechanism of multilayer-shaped cocrystal explosives: compression and slide.

    PubMed

    Gao, Hong-fei; Zhang, Shu-hai; Ren, Fu-de; Gou, Rui-jun; Han, Gang; Wu, Jing-bo; Ding, Xiong; Zhao, Wen-hu

    2016-05-01

    Multilayer-shaped compression and slide models were employed to investigate the complex sensitive mechanisms of cocrystal explosives in response to external mechanical stimuli. Here, density functional theory (DFT) calculations implementing the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) with the Tkatchenko-Scheffler (TS) dispersion correction were applied to a series of cocrystal explosives: diacetone diperoxide (DADP)/1,3,5-trichloro-2,4,6-trinitrobenzene (TCTNB), DADP/1,3,5-tribromo-2,4,6-trinitrobenzene (TBTNB) and DADP/1,3,5-triiodo-2,4,6-trinitrobenzene (TITNB). The results show that the GGA-PBE-TS method is suitable for calculating these cocrystal systems. Compression and slide models illustrate well the sensitive mechanism of layer-shaped cocrystals of DADP/TCTNB and DADP/TITNB, in accordance with the results from electrostatic potentials and free space per molecule in cocrystal lattice analyses. DADP/TCTNB and DADP/TBTNB prefer sliding along a diagonal direction on the a-c face and generating strong intermolecular repulsions, compared to DADP/TITNB, which slides parallel to the b-c face. The impact sensitivity of DADP/TBTNB is predicted to be the same as that of DADP/TCTNB, and the impact sensitivity of DADP/TBTNB may be slightly more insensitive than that of DADP and much more sensitive than that of TBTNB. PMID:27094730

  9. Nonlinear elastic behavior and failure mechanism of polyhedral graphite particles undergoing uniaxial compression

    NASA Astrophysics Data System (ADS)

    Li, B.; Zhang, P.; Fu, Q. Q.; Li, X. F.; Zhao, X.; Song, X. L.

    2014-08-01

    Load-displacement responses and ultimate strength of polyhedral graphite particles (PGPs) undergoing in situ nano-compression at ambient temperature have been studied. The dynamic responses of PGPs to uniaxial loads exhibit a typical nonlinear elastic behavior for graphitic nanomaterials. Based on the analysis of stress-strain relationship, the intrinsic strength is slightly larger than actual ultimate strength, indicating the mechanical properties influenced by the initial defects in PGPs. For a given case, compressive Young's modulus E and third-order elastic modulus D achieve to 12.8 GPa and -13.9 GPa, respectively. Weibull probability analysis confirmed its broad range of structural defects inside PGPs and mechanical properties are sensitive to initial defects. The values of ultimate strength of tested PGPs with diameter of 150-400 nm fall within 2-4.5 GPa, which are in the range between shear elastic modulus C44 of turbo-g (minimum) and C44 of hex-g (maximum) in the literature. The deformation and failure mechanisms are discussed and rationalized in terms of structural factors and elastic moduli of perfect graphite crystals.

  10. Quantitative mechanical analysis of thin compressible polymer monolayers on oxide surfaces.

    PubMed

    Huang, Qian; Yoon, Ilsun; Villanueva, Josh; Kim, Kanguk; Sirbuly, Donald J

    2014-10-28

    A clear understanding of the mechanical behavior of nanometer thick films on nanostructures, as well as developing versatile approaches to characterize their mechanical properties, are of great importance and may serve as the foundation for understanding and controlling molecular interactions at the interface of nanostructures. Here we report on the synthesis of thin, compressible polyethylene glycol (PEG) monolayers with a wet thickness of <20 nm on tin dioxide (SnO2) nanofibers through silane-based chemistries. Nanomechanical properties of such thin PEG films were extensively investigated using atomic force microscopy (AFM). In addition, tip-sample interactions were carefully studied, with different AFM tip modifications (i.e., hydrophilic and hydrophobic) and in different ionic solutions. We find that the steric forces dominate the tip-sample interactions when the polymer film is immersed in solution with salt concentrations similar to biological media (e.g., 1x phosphate buffer solution), while van der Waals and electrostatic forces have minimal contributions. A Dimitriadis thin film polymer compression model shows that the linear elastic regime is reproducible in the initial 50% indentation of these films which have tunable Young's moduli ranging from 5 MPa for the low molecular weight films to 700 kPa for the high molecular weight PEG films. Results are compared with the same PEG films deposited on silicon substrates which helped quantify the structural properties and understand the relationship between the structural and the mechanical properties of PEG films on the SnO2 fibers. PMID:25157609

  11. Enhanced densification, strength and molecular mechanisms in shock compressed porous silicon

    NASA Astrophysics Data System (ADS)

    Lane, J. Matthew D.; Vogler, Tracy J.

    2015-06-01

    In most porous materials, void collapse during shock compression couples mechanical energy to thermal energy. Increased temperature drives up pressures and lowers densities in the final Hugoniot states as compared to full-density samples. Some materials, however, exhibit an anomalous enhanced densification in their Hugoniot states when porosity is introduced. We have recently shown that silicon is such a material, and demonstrated a molecular mechanism for the effect using molecular simulation. We will review results from large-scale non-equilibrium molecular dynamics (NEMD) and Hugoniotstat simulations of shock compressed porous silicon, highlighting the mechanism by which porosity produces local shear which nucleate partial phase transition and localized melting at shock pressures below typical thresholds in these materials. Further, we will characterize the stress states and strength of the material as a function of porosity from 5 to 50 percent and with various porosity microstructures. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  12. Analysis of an evaporator-condenser-separated mechanical vapor compression system

    NASA Astrophysics Data System (ADS)

    Wu, Hong; Li, Yulong; Chen, Jiang

    2013-04-01

    An evaporator-condenser-separated mechanical vapor compression (MVC) system was presented. The better effect of descaling and antiscaling was obtained by the new system. This study focused on the method of thermodynamic analysis, and the energy and exergy flow diagrams were established by using the first and second law of thermodynamics analysis. The results show that the energy utilization rate is very high and the specific power consumption is low. Exergy analysis indicates that the exergy efficiency is low, and the largest exergy loss occurs within the evaporator -condenser and the compressor.

  13. Mechanical behavior of human embryonic stem cell pellet under unconfined compression.

    PubMed

    Ma, Gang; Petersen, Erik; Leong, Kam W; Liao, Kin

    2012-05-01

    As a prelude to the understanding of mechanotransduction in human embryonic stem cell (hESC) differentiation, the mechanical behavior of hESCs in the form of cell pellet is studied. The pellets were tested after 3 or 5 weeks of cell culture in order to demonstrate the effect of the duration of cell culture on the mechanical properties of the pellets. A micromechanical tester was used to conduct unconfined compression on hESC pellet, and experimental, numerical, and analytical methods were combined to determine the mechanical properties of hESC pellet. It is assumed that the mechanical behavior of hESC pellets can be described by an isotropic, linear viscoelastic model consisting of a spring and two Maxwell units in parallel, and the Poisson's ratio of the hESC pellet is constant based on pellet deformation in the direction perpendicular to the compression direction. Finite element method (FEM) simulation was adopted to determine the values of Poisson's ratio and the five parameters contained in the viscoelastic model. The variations of Poisson's ratio and the initial elastic modulus are found to be larger compared with those of the four other parameters. Results show that longer duration of cell culture leads to higher modulus of hESC pellet. The effect of pellet size error on the values of mechanical parameters determined is studied using FEM simulation, and it is found that the effect of size error on Poisson's ratio and initial elastic modulus is much larger than that on the other parameters. PMID:21858691

  14. A reduced mechanism for biodiesel surrogates with low temperature chemistry for compression ignition engine applications

    NASA Astrophysics Data System (ADS)

    Luo, Zhaoyu; Plomer, Max; Lu, Tianfeng; Som, Sibendu; Longman, Douglas E.

    2012-04-01

    Biodiesel is a promising alternative fuel for compression ignition (CI) engines. It is a renewable energy source that can be used in these engines without significant alteration in design. The detailed chemical kinetics of biodiesel is however highly complex. In the present study, a skeletal mechanism with 123 species and 394 reactions for a tri-component biodiesel surrogate, which consists of methyl decanoate, methyl 9-decanoate and n-heptane was developed for simulations of 3-D turbulent spray combustion under engine-like conditions. The reduction was based on an improved directed relation graph (DRG) method that is particularly suitable for mechanisms with many isomers, followed by isomer lumping and DRG-aided sensitivity analysis (DRGASA). The reduction was performed for pressures from 1 to 100 atm and equivalence ratios from 0.5 to 2 for both extinction and ignition applications. The initial temperatures for ignition were from 700 to 1800 K. The wide parameter range ensures the applicability of the skeletal mechanism under engine-like conditions. As such the skeletal mechanism is applicable for ignition at both low and high temperatures. Compared with the detailed mechanism that consists of 3299 species and 10806 reactions, the skeletal mechanism features a significant reduction in size while still retaining good accuracy and comprehensiveness. The validations of ignition delay time, flame lift-off length and important species profiles were also performed in 3-D engine simulations and compared with the experimental data from Sandia National Laboratories under CI engine conditions.

  15. Mechanical compression and nucleus pulposus application on dorsal root Ganglia differentially modify evoked neuronal activity in the thalamus.

    PubMed

    Nilsson, Elin; Brisby, Helena; Rask, Katarina; Hammar, Ingela

    2013-06-01

    A combination of mechanical compression caused by a protruding disc and leakage of nucleus pulposus (NP) from the disc core is presumed to contribute to intervertebral disc hernia-related pain. Experimental models of disc hernia including both components have resulted in changes in neuronal activity at the level of the dorsal root ganglion (DRG) and spinal cord, but changes within the brain have been less well studied. However, acute application of NP to a DRG without mechanical compression rapidly increases neuronal activity in the thalamus, a major brain relay nucleus processing information from sensory pathways including ascending nociceptive tracts. The combination of mechanical compression and NP might therefore result in further increases in central neuronal activity. Using an experimental disc herniation rat model including both mechanical compression and NP the present study aimed to investigate changes in neuronal activity in the contralateral thalamic ventral posterior lateral nucleus in vivo. Measurements were obtained while electrically stimulating the ipsilateral sciatic nerve at Aδ fiber intensities. The L4 DRG was subjected to light mechanical compression and NP exposure, and acute changes in evoked thalamic responses were recorded for up to 40 min. In order to compare effects in naïve animals with effects following a longer period of NP exposure, animals that were either disc-punctured or sham-operated 24 h previously were also included. In all animals, light mechanical compression of the DRG depressed the number of evoked neuronal responses. Prior NP exposure resulted in less potent changes following mechanical compression (80% of baseline) than that observed in naïve animals (50%). During the subsequent NP application, the number of evoked responses compared to baseline increased in pre-exposed animals (to 87%) as well as in naïve animals (72%) in which the removal of the mechanical compression resulted in a further increase (106%). The

  16. Normal and Fibrotic Rat Livers Demonstrate Shear Strain Softening and Compression Stiffening: A Model for Soft Tissue Mechanics

    PubMed Central

    Cao, Xuan; van Oosten, Anne; Shenoy, Vivek B.; Janmey, Paul A.; Wells, Rebecca G.

    2016-01-01

    Tissues including liver stiffen and acquire more extracellular matrix with fibrosis. The relationship between matrix content and stiffness, however, is non-linear, and stiffness is only one component of tissue mechanics. The mechanical response of tissues such as liver to physiological stresses is not well described, and models of tissue mechanics are limited. To better understand the mechanics of the normal and fibrotic rat liver, we carried out a series of studies using parallel plate rheometry, measuring the response to compressive, extensional, and shear strains. We found that the shear storage and loss moduli G’ and G” and the apparent Young's moduli measured by uniaxial strain orthogonal to the shear direction increased markedly with both progressive fibrosis and increasing compression, that livers shear strain softened, and that significant increases in shear modulus with compressional stress occurred within a range consistent with increased sinusoidal pressures in liver disease. Proteoglycan content and integrin-matrix interactions were significant determinants of liver mechanics, particularly in compression. We propose a new non-linear constitutive model of the liver. A key feature of this model is that, while it assumes overall liver incompressibility, it takes into account water flow and solid phase compressibility. In sum, we report a detailed study of non-linear liver mechanics under physiological strains in the normal state, early fibrosis, and late fibrosis. We propose a constitutive model that captures compression stiffening, tension softening, and shear softening, and can be understood in terms of the cellular and matrix components of the liver. PMID:26735954

  17. Normal and Fibrotic Rat Livers Demonstrate Shear Strain Softening and Compression Stiffening: A Model for Soft Tissue Mechanics.

    PubMed

    Perepelyuk, Maryna; Chin, LiKang; Cao, Xuan; van Oosten, Anne; Shenoy, Vivek B; Janmey, Paul A; Wells, Rebecca G

    2016-01-01

    Tissues including liver stiffen and acquire more extracellular matrix with fibrosis. The relationship between matrix content and stiffness, however, is non-linear, and stiffness is only one component of tissue mechanics. The mechanical response of tissues such as liver to physiological stresses is not well described, and models of tissue mechanics are limited. To better understand the mechanics of the normal and fibrotic rat liver, we carried out a series of studies using parallel plate rheometry, measuring the response to compressive, extensional, and shear strains. We found that the shear storage and loss moduli G' and G" and the apparent Young's moduli measured by uniaxial strain orthogonal to the shear direction increased markedly with both progressive fibrosis and increasing compression, that livers shear strain softened, and that significant increases in shear modulus with compressional stress occurred within a range consistent with increased sinusoidal pressures in liver disease. Proteoglycan content and integrin-matrix interactions were significant determinants of liver mechanics, particularly in compression. We propose a new non-linear constitutive model of the liver. A key feature of this model is that, while it assumes overall liver incompressibility, it takes into account water flow and solid phase compressibility. In sum, we report a detailed study of non-linear liver mechanics under physiological strains in the normal state, early fibrosis, and late fibrosis. We propose a constitutive model that captures compression stiffening, tension softening, and shear softening, and can be understood in terms of the cellular and matrix components of the liver. PMID:26735954

  18. A Current Review of Mechanical Compression and Its Role in Venous Thromboembolic Prophylaxis in Total Knee and Total Hip Arthroplasty.

    PubMed

    Pierce, Todd P; Cherian, Jeffrey J; Jauregui, Julio J; Elmallah, Randa K; Lieberman, Jay R; Mont, Michael A

    2015-12-01

    Interest in mechanical compression for venous thromboembolic disease prophylaxis has increased over the last several years because of concerns related to bleeding complications associated with chemoprophylaxis. However, the research evaluating compression is clearly not definitive. Therefore, this review aims to: (1) summarize methods of compression; (2) compare AAOS, ACCP, and SCIP guidelines; and (3) make recommendations regarding usage. Below-the-knee devices have demonstrated the most efficacy with multiple guidelines recommending usage. Efficacy and compliance may be improved with the use of mobile devices. PMID:26048728

  19. Designed composites for mimicking compressive mechanical properties of articular cartilage matrix.

    PubMed

    Zhu, Youjia; Wu, Hua; Sun, Shaofa; Zhou, Ting; Wu, Jingjing; Wan, Ying

    2014-08-01

    Collagen, chitosan-polycaprolactone (CH-PCL) copolymer with PCL content of around 40wt% and chondroitin sulfate (CS) were mixed together at various ratios to prepare collagen/CH-PCL/CS composites and the resulting composites were used to build stratified porous scaffolds that are potentially applicable for articular cartilage repair. The ternary composites were designed in such a way that collagen content in the scaffolds decreased from the top layer to the bottom layer while the content of CH-PCL and CS altered in a reversed trend in order to reach partial similarity to cartilage matrix in the composition of main components. Porous structures inside collagen/CH-PCL/CS scaffolds were constructed using a low-temperature deposition processing technique and graded average pore-size and porosity for the scaffolds were established. Such produced scaffolds were further crosslinked using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide under optimized conditions, and the obtained scaffolds showed well-defined elastic compressive properties. Compressive modulus (E) and stress at 10% strain (σ10) of full scaffolds in wet state reached about 2.8MPa and 0.3MPa, respectively, and meanwhile, E and σ10 of layers inside hydrated scaffolds changed in a gradient-increased manner from the top layer to the bottom layer with significant differences between contiguous layers, which partially mimics compressive mechanical properties of cartilage matrix. In addition, in vitro culture of cell-scaffold constructs exhibited that scaffolds were able to well support the ingrowth and migration of seeded cells, and cells also showed relatively uniform distribution throughout the scaffolds. These results suggest that the presently developed collagen/CH-PCL/CS scaffolds have promising potential for applications in articular cartilage repair. PMID:24793172

  20. Detailed Chemical Kinetic Reaction Mechanisms for Autoignition of Isomers of Heptane Under Rapid Compression

    SciTech Connect

    Westbrook, C K; Pitz, W J; Boercker, J E; Curran, H J; Griffiths, J F; Mohamed, C; Ribaucour, M

    2001-12-17

    Detailed chemical kinetic reaction mechanisms are developed for combustion of all nine isomers of heptane (C{sub 7}H{sub 16}), and these mechanisms are tested by simulating autoignition of each isomer under rapid compression machine conditions. The reaction mechanisms focus on the manner in which the molecular structure of each isomer determines the rates and product distributions of possible classes of reactions. The reaction pathways emphasize the importance of alkylperoxy radical isomerizations and addition reactions of molecular oxygen to alkyl and hydroperoxyalkyl radicals. A new reaction group has been added to past models, in which hydroperoxyalkyl radicals that originated with abstraction of an H atom from a tertiary site in the parent heptane molecule are assigned new reaction sequences involving additional internal H atom abstractions not previously allowed. This process accelerates autoignition in fuels with tertiary C-H bonds in the parent fuel. In addition, the rates of hydroperoxyalkylperoxy radical isomerization reactions have all been reduced so that they are now equal to rates of analogous alkylperoxy radical isomerizations, significantly improving agreement between computed and experimental ignition delay times in the rapid compression machine. Computed ignition delay times agree well with experimental results in the few cases where experiments have been carried out for specific heptane isomers, and predictive model calculations are reported for the remaining isomers. The computed results fall into three general groups; the first consists of the most reactive isomers, including n-heptane, 2-methyl hexane and 3-methyl hexane. The second group consists of the least reactive isomers, including 2,2-dimethyl pentane, 3,3-dimethyl pentane, 2,3-dimethyl pentane, 2,4-dimethyl pentane and 2,2,3-trimethyl butane. The remaining isomer, 3-ethyl pentane, was observed computationally to have an intermediate level of reactivity. These observations are generally

  1. Mechanism for amorphization of boron carbide B4C under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Aryal, Sitaram; Rulis, Paul; Ching, W. Y.

    2011-11-01

    Boron carbide undergoes an amorphization transition under high-velocity impacts, causing it to suffer a catastrophic loss in strength. The failure mechanism is not clear and this limits the ways to improve its resistance to impact. To help uncover the failure mechanism, we used ab initio methods to carry out large-scale uniaxial compression simulations on two polytypes of stoichiometric boron carbide (B4C), B11C-CBC, and B12-CCC, where B11C or B12 is the 12-atom icosahedron and CBC or CCC is the three-atom chain. The simulations were performed on large supercells of 180 atoms. Our results indicate that the B11C-CBC (B12-CCC) polytype becomes amorphous at a uniaxial strain s = 0.23 (0.22) and with a maximum stress of 168 (151) GPa. In both cases, the amorphous state is the consequence of structural collapse associated with the bending of the three-atom chain. Careful analysis of the structures after amorphization shows that the B11C and B12 icosahedra are highly distorted but still identifiable. Calculations of the elastic coefficients (Cij) at different uniaxial strains indicate that both polytypes may collapse under a much smaller shear strain (stress) than the uniaxial strain (stress). On the other hand, separate simulations of both models under hydrostatic compression up to a pressure of 180 GPa show no signs of amorphization, in agreement with experimental observation. The amorphized nature of both models is confirmed by detailed analysis of the evolution of the radial pair distribution function, total density of states, and distribution of effective charges on atoms. The electronic structure and bonding of the boron carbide structures before and after amorphization are calculated to further elucidate the mechanism of amorphization and to help form the proper rationalization of experimental observations.

  2. Mechanism for amorphization of boron carbide B{sub 4}C under uniaxial compression

    SciTech Connect

    Aryal, Sitaram; Rulis, Paul; Ching, W. Y.

    2011-11-01

    Boron carbide undergoes an amorphization transition under high-velocity impacts, causing it to suffer a catastrophic loss in strength. The failure mechanism is not clear and this limits the ways to improve its resistance to impact. To help uncover the failure mechanism, we used ab initio methods to carry out large-scale uniaxial compression simulations on two polytypes of stoichiometric boron carbide (B{sub 4}C), B{sub 11}C-CBC, and B{sub 12}-CCC, where B{sub 11}C or B{sub 12} is the 12-atom icosahedron and CBC or CCC is the three-atom chain. The simulations were performed on large supercells of 180 atoms. Our results indicate that the B{sub 11}C-CBC (B{sub 12}-CCC) polytype becomes amorphous at a uniaxial strain s = 0.23 (0.22) and with a maximum stress of 168 (151) GPa. In both cases, the amorphous state is the consequence of structural collapse associated with the bending of the three-atom chain. Careful analysis of the structures after amorphization shows that the B{sub 11}C and B{sub 12} icosahedra are highly distorted but still identifiable. Calculations of the elastic coefficients (C{sub ij}) at different uniaxial strains indicate that both polytypes may collapse under a much smaller shear strain (stress) than the uniaxial strain (stress). On the other hand, separate simulations of both models under hydrostatic compression up to a pressure of 180 GPa show no signs of amorphization, in agreement with experimental observation. The amorphized nature of both models is confirmed by detailed analysis of the evolution of the radial pair distribution function, total density of states, and distribution of effective charges on atoms. The electronic structure and bonding of the boron carbide structures before and after amorphization are calculated to further elucidate the mechanism of amorphization and to help form the proper rationalization of experimental observations.

  3. Noncardiac chest pain: epidemiology, natural course and pathogenesis.

    PubMed

    Fass, Ronnie; Achem, Sami R

    2011-04-01

    Noncardiac chest pain is defined as recurrent chest pain that is indistinguishable from ischemic heart pain after a reasonable workup has excluded a cardiac cause. Noncardiac chest pain is a prevalent disorder resulting in high healthcare utilization and significant work absenteeism. However, despite its chronic nature, noncardiac chest pain has no impact on patients' mortality. The main underlying mechanisms include gastroesophageal reflux, esophageal dysmotility and esophageal hypersensitivity. Gastroesophageal reflux disease is likely the most common cause of noncardiac chest pain. Esophageal dysmotility affects only the minority of noncardiac chest pain patients. Esophageal hypersensitivity may be present in non-GERD-related noncardiac chest pain patients regardless if esophageal dysmotility is present or absent. Psychological co-morbidities such as panic disorder, anxiety, and depression are also common in noncardiac chest pain patients and often modulate patients' perception of disease severity. PMID:21602987

  4. A flex-compressive-mode piezoelectric transducer for mechanical vibration/strain energy harvesting.

    PubMed

    Li, Xiaotian; Guo, Mingsen; Dong, Shuxiang

    2011-04-01

    A piezoelectric transducer for harvesting energy from ambient mechanical vibrations/strains under pressure condition was developed. The proposed transducer was made of two ring-type piezoelectric stacks, one pair of bow-shaped elastic plates, and one shaft that pre-compresses them. This transducer works in flex-compressive (F-C) mode, which is different from a conventional flex-tensional (F-T) one, to transfer a transversely applied force F into an amplified longitudinal force N pressing against the two piezo-stacks via the two bowshaped elastic plates, generating a large electric voltage output via piezoelectric effect. Our experimental results show that without an electric load, an F-C mode piezo-transducer could generate a maximum electric voltage output of up to 110 Vpp, and with an electric load of 40 κΩ, it a maximum power output of 14.6 mW under an acceleration excitation of 1 g peak-peak at the resonance frequency of 87 Hz. PMID:21507747

  5. Electrical, mechanical and morphological properties of compressed carbon felt electrodes in vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Chang, Tien-Chan; Zhang, Jun-Pu; Fuh, Yiin-Kuen

    2014-01-01

    Experiments including electrical, mechanical and morphological aspects under compression in the range of 0-40% have been carried out on four potential materials for liquid diffusion layer (LDL) of vanadium redox flow battery (VRB) (including three widely used carbon felt and one recently utilized metal foam) in order to better understand the influence of the fundamental properties on the battery performance. We experimentally demonstrate that the electrical contact resistance is predominately determined by the clamping force. It is observed that increasing the stress applied on the carbon felt, which is of high interest for the durability of the membrane electrode assembly (MEA), has moreover a positive effect on their performance due to the reduced contact resistance. However, a simultaneously reduced porosity is also recorded and possibly detrimental to the mass transport of vanadium electrolyte. Moreover, the intrusion of carbon felts under compression is also characterized. Experimental results show that with the clamping force increases, both the porosity of the carbon felts underneath the rib and channel volume decrease, and this can be mainly attributed to the deformation of the carbon felts and resultant changed of the void volume as well as intrusion.

  6. Failure analysis of porcupine quills under axial compression reveals their mechanical response during buckling.

    PubMed

    Torres, Fernando G; Troncoso, Omar P; Diaz, John; Arce, Diego

    2014-11-01

    Porcupine quills are natural structures formed by a thin walled conical shell and an inner foam core. Axial compression tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR) were all used to compare the characteristics and mechanical properties of porcupine quills with and without core. The failure mechanisms that occur during buckling were analyzed by scanning electron microscopy (SEM), and it was found that delamination buckling is mostly responsible for the decrease in the measured buckling stress of the quills with regard to predicted theoretical values. Our analysis also confirmed that the foam core works as an energy dissipater improving the mechanical response of an empty cylindrical shell, retarding the onset of buckling as well as producing a step wise decrease in force after buckling, instead of an instantaneous decrease in force typical for specimens without core. Cell collapse and cell densification in the inner foam core were identified as the key mechanisms that allow for energy absorption during buckling. PMID:25123434

  7. Compression strength failure mechanisms in unidirectional composite laminates containing a hole

    NASA Technical Reports Server (NTRS)

    Johnson, Eric R.

    1993-01-01

    Experiments on graphite-epoxy laminated plates containing unloaded small holes show that these laminates are notch insensitive. That is, the uniaxial strength of these laminates with small holes exceeds the strength predicted by a point stress criterion using the stress concentration factor for the in-plane stress field. Laminates containing large holes exhibit notch sensitive behavior and consequently their strength is reasonably well predicted by the stress concentration effect. This hole size effect is manifested both in tension and in compression. Apparently, some mechanism must cause in-plane stress relief for laminates containing small holes. The purpose of this research was to study the influence of geometric nonlinearity on the micromechanical response of a filamentary composite material in the presence of a strain gradient caused by a discontinuity such as a hole. A mathematical model was developed at the micromechanical level to investigate this geometrically nonlinear effect.

  8. Transforming powder mechanical properties by core/shell structure: compressible sand.

    PubMed

    Shi, Limin; Sun, Changquan Calvin

    2010-11-01

    Some active pharmaceutical ingredients possess poor mechanical properties and are not suitable for tableting. Using fine sand (silicon dioxide), we show that a core/shell structure, where a core particle (sand) is coated with a thin layer of polyvinylpyrrolidone (PVP), can profoundly improve powder compaction properties. Sand coated with 5% PVP could be compressed into intact tablets. Under a given compaction pressure, tablet tensile strength increases dramatically with the amount of coating. This is in sharp contrast to poor compaction properties of physical mixtures, where intact tablets cannot be made when PVP content is 20% or less. The profoundly improved tabletability of core/shell particles is attributed to the formation of a continuous three-dimensional bonding network in the tablet. PMID:20845444

  9. Mechanism of hollow-core-fiber infrared-supercontinuum compression with bulk material

    SciTech Connect

    Bejot, P.; Schmidt, B. E.; Legare, F.; Kasparian, J.; Wolf, J.-P.

    2010-06-15

    We numerically investigate the pulse compression mechanism in the infrared spectral range based on the successive action of nonlinear pulse propagation in a hollow-core fiber followed by linear propagation through bulk material. We found an excellent agreement of simulated pulse properties with experimental results at 1.8 {mu}m in the two-optical-cycle regime close to the Fourier limit. In particular, the spectral phase asymmetry attributable to self-steepening combined with self-phase modulation is a necessary prerequisite for subsequent compensation by the phase introduced by glass material in the anomalous dispersion regime. The excellent agreement of the model enabled simulating pressure and wavelength tunability of sub-two cycles in the range from 1.5 to 4 {mu}m with this cost-efficient and robust approach.

  10. Computer-aided study of the mechanical behavior of the jaw bone fragments under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Kolmakova, Tatyana V.

    2016-08-01

    The article presents the calculated results of the mechanical behavior of simulative bone mesovolumes under uniaxial compression with their architectonics corresponding to the human jaw bone fragments. The results of the calculation show that changes in the structure and mineral content of the bone fragments can lead to the change of their prevailing deformation response. New effective parameters were introduced to reflect the character of the distribution of stresses and strains in the bone mesovolumes. Implants are to be created and selected to correspond to the offered parameters and longitudinal modulus of elasticity of bone mesovolumes in order to maintain the stress and strain state existing in bone macrovolume during the implantation and in order to avoid bone restructuring through its borderline resorption.

  11. Compressed Sensing in a Fully Non-Mechanical 350 GHz Imaging Setting

    NASA Astrophysics Data System (ADS)

    Augustin, S.; Hieronymus, J.; Jung, P.; Hübers, H.-W.

    2015-05-01

    We investigate a single-pixel camera (SPC) that relies on non-mechanical scanning with a terahertz (THz) spatial light modulator (SLM) and Compressed Sensing (CS) for image generation. The camera is based on a 350 GHz multiplier source and a Golay cell detector. The SLM consists of a Germanium disc, which is illuminated by a halogen lamp. The light of the lamp is transmitted through a thin-film transistor (TFT) liquid crystal display (LCD). This enables the generation of light patterns on the Germanium disc, which in turn produce reflecting patterns for THz radiation. Using up to 1000 different patterns the pseudo-inverse reconstruction algorithm and the CS algorithm CoSaMP are evaluated with respect to image quality. It is shown that CS allows a reduction of the necessary measurements by a factor of three without compromising the image quality.

  12. Vertebrae in compression: Mechanical behavior of arches and centra in the gray smooth-hound shark (Mustelus californicus).

    PubMed

    Porter, Marianne E; Long, John H

    2010-03-01

    In swimming sharks, vertebrae are subjected, in part, to compressive loads as axial muscles contract. We currently have no information about which vertebral elements, centra, arch cartilages, or both, actually bear compressive loads in cartilaginous vertebrae. To address this issue, the goal of this experiment was to determine the load-bearing ability of arch and centrum cartilages in compression, to determine the material properties of shark vertebrae, and to document fracture patterns in the centra with and without the arches. Intact vertebrae and vertebrae with the arch cartilages experimentally removed (centra alone) were subjected to compressive loading to failure at a single strain rate. The maximum compressive forces sustained by the vertebrae and the centra are statistically indistinguishable. Thus we conclude that under these testing conditions the arch does not bear appreciable loads. Independent evidence for this conclusion comes from the fact that vertebrae fail in compression at the centra, and not at the arches. Overall, the results of these mechanical tests suggest that the neural arches are not the primary load-bearing structure during axial compression. PMID:19862836

  13. An analysis of the mechanical parameters used for finite element compression of a high-resolution 3D breast phantom

    PubMed Central

    Hsu, Christina M. L.; Palmeri, Mark L.; Segars, W. Paul; Veress, Alexander I.; Dobbins, James T.

    2011-01-01

    Purpose: The authors previously introduced a methodology to generate a realistic three-dimensional (3D), high-resolution, computer-simulated breast phantom based on empirical data. One of the key components of such a phantom is that it provides a means to produce a realistic simulation of clinical breast compression. In the current study, they have evaluated a finite element (FE) model of compression and have demonstrated the effect of a variety of mechanical properties on the model using a dense mesh generated from empirical breast data. While several groups have demonstrated an effective compression simulation with lower density finite element meshes, the presented study offers a mesh density that is able to model the morphology of the inner breast structures more realistically than lower density meshes. This approach may prove beneficial for multimodality breast imaging research, since it provides a high level of anatomical detail throughout the simulation study. Methods: In this paper, the authors describe methods to improve the high-resolution performance of a FE compression model. In order to create the compressible breast phantom, dedicated breast CT data was segmented and a mesh was generated with 4-noded tetrahedral elements. Using an explicit FE solver to simulate breast compression, several properties were analyzed to evaluate their effect on the compression model including: mesh density, element type, density, and stiffness of various tissue types, friction between the skin and the compression plates, and breast density. Following compression, a simulated projection was generated to demonstrate the ability of the compressible breast phantom to produce realistic simulated mammographic images. Results: Small alterations in the properties of the breast model can change the final distribution of the tissue under compression by more than 1 cm; which ultimately results in different representations of the breast model in the simulated images. The model

  14. DIFFERENCES IN THE MECHANICAL BEHAVIOR OF CORTICAL BONE BETWEEN COMPRESSION AND TENSION WHEN SUBJECTED TO PROGRESSIVE LOADING

    PubMed Central

    Nyman, Jeffry S.; Ling, Huijie; Dong, Xuanliang; Wang, Xiaodu

    2008-01-01

    The hierarchical arrangement of collagen and mineral into bone tissue presumabley maximizes fracture resistance with respect to the predominant strain mode in bone. Thus, the ability of cortical bone to dissipate energy may differ between compression and tension for the same anatomical site. To test this notion, we subjected bone specimens from the anterior quadrant of human cadaveric tibiae to a progressive loading scheme in either uniaxial tension or uniaxial compression. One tension (dog-bone shape) and one compression specimen (cylindrical shape) were collected each from tibiae of nine middle aged male donors. At each cycle of loading-dwell-unloading-dwell-reloading, we calculated maximum stress, permanent strain, modulus, stress relaxation, time constant, and 3 pathways of energy dissipation for both loading modes. In doing so, we found that bone dissipated greater energy through the mechanisms of permanent and viscoelastic deformation in compression than in tension. On the other hand, however, bone dissipated greater energy through the release of surface energy in tension than in compression. Moreover, differences in the plastic and viscoelastic properties after yielding were not reflected in the evolution of modulus loss (an indicator of damage accumulation), which was similar for both loading modes. A possible explanation is that differences in damage morphology between the two loading modes may favor the plastic and viscolelastic energy dissipation in compression, but facilitate the surface energy release in tension. Such detailed information about failure mechanisms of bone at the tissue-level would help explain the underlying causes of bone fractures. PMID:19716106

  15. Deformation mechanism of basic rock during long-term compression: Area of HLW repository design, Chelyabinsk District, Russia

    SciTech Connect

    Petrov, V.A.; Zviagintsev, L.I.; Poluektov, V.V.

    1996-08-01

    A combination of ultrasound, mechanical and petrographic results for long-term experimental compression of greenschist facies porphyritic andesite tuffs indicate a deformation mechanism that depends upon the mineral composition, textural-structural features of the rocks and the orientation of compression relative to the rock textures. Three dry samples of rock were investigated. Coaxial compression of a massive sample for 816 hours and a foliated sample for 1,176 hours (pressure orthogonal to foliation) is characterized by solidification when the rocks are temporarily metastable. Compressive strength of the first sample is 850 kg/cm{sup 2} and of the second one, 800 kg/cm{sup 2}. Experimentally, the rock behavior changes from a plastic to a brittle regime of deformation. In contrast, compression of the foliated sample parallel to foliation causes disintegration along the foliation within 480 hours without solidification. The rock is liable to brittle deformation and its compressive strength is 500 kg/cm{sup 2}. These results may have implications for characterization of near-field processes in connection with numerous subhorizontal zones of schistosity within the strata that are targeted for underground disposal of high-level wastes (HLW) in the Mayak radiochemical complex area.

  16. Synchronization of radiograph film exposure with the inspiratory pause. Effect on the appearance of bedside chest radiographs in mechanically ventilated patients.

    PubMed

    Langevin, P B; Hellein, V; Harms, S M; Tharp, W K; Cheung-Seekit, C; Lampotang, S

    1999-12-01

    The appearance of portable chest radiographs (CXRs) may be affected by changes in ventilation, particularly when patients are mechanically ventilated. Synchronization of the CXR with the ventilatory cycle should limit the influence of respiratory variation on the appearance of the CXR. This study evaluates the effect of synchronizing the CXR film exposure with ventilation on the appearance of the radiograph. Twenty-five patients who remained intubated postoperatively, were mechanically ventilated, and required a CXR were enrolled in this triple-blind, randomized prospective study. Each patient received one radiograph using conventional techniques and another using the interface. The sequence of the two films was randomized, and the two films were taken on the same patient within a few minutes of each other. Hence, each patient served as his own control and the position of the patient, source-film distance, intensity (Kvp), and duration of the exposure (mAs) were identical for the two films. Five board-certified radiologists were then asked to compare paired films for clarity of lines and tubes, definition of the pulmonary vasculature, visibility of the mediastinum, definition of the diaphragm, and degree of lung inflation. Radiologists were also asked to choose which films they preferred. A majority of board certified radiologists preferred CXRs taken with the interface in 21 of 25 patients (p < 0.0001). Furthermore, four of the five criteria evaluated were improved (p < 0.05) on synchronized CXRs. Synchronization of the bedside CXR with the end of inspiration ensures that they are always obtained at maximal inflation, which improves the appearance of a majority of radiographs by at least one of five criteria. PMID:10588630

  17. Prevalence and mechanism of triazole resistance in Aspergillus fumigatus in a referral chest hospital in Delhi, India and an update of the situation in Asia

    PubMed Central

    Chowdhary, Anuradha; Sharma, Cheshta; Kathuria, Shallu; Hagen, Ferry; Meis, Jacques F.

    2015-01-01

    Aspergillus fumigatus causes varied clinical syndromes ranging from colonization to deep infections. The mainstay of therapy of Aspergillus diseases is triazoles but several studies globally highlighted variable prevalence of triazole resistance, which hampers the management of aspergillosis. We studied the prevalence of resistance in clinical A. fumigatus isolates during 4 years in a referral Chest Hospital in Delhi, India and reviewed the scenario in Asia and the Middle East. Aspergillus species (n = 2117) were screened with selective plates for azole resistance. The isolates included 45.4% A. flavus, followed by 32.4% A. fumigatus, 15.6% Aspergillus species and 6.6% A. terreus. Azole resistance was found in only 12 (1.7%) A. fumigatus isolates. These triazole resistant A. fumigatus (TRAF) isolates were subjected to (a) calmodulin and β tubulin gene sequencing (b) in vitro antifungal susceptibility testing against triazoles using CLSI M38-A2 (c) sequencing of cyp51A gene and real-time PCR assay for detection of mutations and (d) microsatellite typing of the resistant isolates. TRAF harbored TR34/L98H mutation in 10 (83.3%) isolates with a pan-azole resistant phenotype. Among the remaining two TRAF isolates, one had G54E and the other had three non-synonymous point mutations. The majority of patients were diagnosed as invasive aspergillosis followed by allergic bronchopulmonary aspergillosis and chronic pulmonary aspergillosis. The Indian TR34/L98H isolates had a unique genotype and were distinct from the Chinese, Middle East, and European TR34/L98H strains. This resistance mechanism has been linked to the use of fungicide azoles in agricultural practices in Europe as it has been mainly reported from azole naïve patients. Reports published from Asia demonstrate the same environmental resistance mechanism in A. fumigatus isolates from two highly populated countries in Asia, i.e., China and India and also from the neighboring Middle East. PMID:26005442

  18. Scaling laws and deformation mechanisms of nanoporous copper under adiabatic uniaxial strain compression

    SciTech Connect

    Yuan, Fuping Wu, Xiaolei

    2014-12-15

    A series of large-scale molecular dynamics simulations were conducted to investigate the scaling laws and the related atomistic deformation mechanisms of Cu monocrystal samples containing randomly placed nanovoids under adiabatic uniaxial strain compression. At onset of yielding, plastic deformation is accommodated by dislocations emitted from void surfaces as shear loops. The collapse of voids are observed by continuous emissions of dislocations from void surfaces and their interactions with further plastic deformation. The simulation results also suggest that the effect modulus, the yield stress and the energy aborption density of samples under uniaxial strain are linearly proportional to the relative density ρ. Moreover, the yield stress, the average flow stress and the energy aborption density of samples with the same relative density show a strong dependence on the void diameter d, expressed by exponential relations with decay coefficients much higher than -1/2. The corresponding atomistic mechanisms for scaling laws of the relative density and the void diameter were also presented. The present results should provide insights for understanding deformation mechanisms of nanoporous metals under extreme conditions.

  19. Statistical mechanics description of an isotropic compression and its relationship to micromechanics

    NASA Astrophysics Data System (ADS)

    Oquendo, W. F.; Muñoz, J. D.

    2013-06-01

    Statistical mechanics of volumes have been used to describe static packings of grains, usually grown by deposition or after shaking. In the present work, we use molecular dynamic simulations and the Gamma distribution of volumes introduced by Aste et. al [1, 2] to explore the limit equilibrium state of isotropic compression on a monodisperse system of spheres with sliding and rolling friction. The objective is to investigate how the volume entropy S, the compactivity χ and the number of elementary cells per particle C/N change with the microscopic force parameters among grains. First, we found that the volume distribution of the Voronoi tessellation on the final state actually follows the Gamma distribution proposed by Aste et. al. Next, we found that both S and χ grow smoothly by a factor of two with an increasing sliding friction coefficient μs, which, therefore, could be used as tunning parameter for these statistical variables. They also grow with the rolling friction coefficient μr, but for a smaller factor and reaching saturation very early. In contrast, C/N is almost unaffected by μr (between the error bars) and saturates for very small values of μs, but it can be reduced in around a 10% by decreasing the reduced elastic constant κ in two orders of magnitude, a change that does leave χ almost unaffected. These results drive the attention on μs as the most meaningful variable to control the reorganizations of grains through the isotropic compression and, thus, the statistical properties of its final state.

  20. Dynamic Compression Effects on Immature Nucleus Pulposus: a Study Using a Novel Intelligent and Mechanically Active Bioreactor

    PubMed Central

    Li, Pei; Gan, Yibo; Wang, Haoming; Zhang, Chengmin; Wang, Liyuan; Xu, Yuan; Song, Lei; Li, Songtao; Li, Sukai; Ou, Yangbin; Zhou, Qiang

    2016-01-01

    Background: Previous cell culture and animal in vivo studies indicate the obvious effects of mechanical compression on disc cell biology. However, the effects of dynamic compression magnitude, frequency and duration on the immature nucleus pulposus (NP) from an organ-cultured disc are not well understood. Objective: To investigate the effects of a relatively wide range of compressive magnitudes, frequencies and durations on cell apoptosis and matrix composition within the immature NP using an intelligent and mechanically active bioreactor. Methods: Discs from the immature porcine were cultured in a mechanically active bioreactor for 7 days. The discs in various compressive magnitude groups (0.1, 0.2, 0.4, 0.8 and 1.3 MPa at a frequency of 1.0 Hz for 2 hours), frequency groups (0.1, 0.5, 1.0, 3.0 and 5.0 Hz at a magnitude of 0.4 MPa for 2 hours) and duration groups (1, 2, 4 and 8 hours at a magnitude of 0.4 MPa and frequency of 1.0 Hz) experienced dynamic compression once per day. Discs cultured without compression were used as controls. Immature NP samples were analyzed using the TUNEL assay, histological staining, glycosaminoglycan (GAG) content measurement, real-time PCR and collagen II immunohistochemical staining. Results: In the 1.3 MPa, 5.0 Hz and 8 hour groups, the immature NP showed a significantly increase in apoptotic cells, a catabolic gene expression profile with down-regulated matrix molecules and up-regulated matrix degradation enzymes, and decreased GAG content and collagen II deposition. In the other compressive magnitude, frequency and duration groups, the immature NP showed a healthier status regarding NP cell apoptosis, gene expression profile and matrix production. Conclusion: Cell apoptosis and matrix composition within the immature NP were compressive magnitude-, frequency- and duration-dependent. The relatively high compressive magnitude or frequency and long compressive duration are not helpful for maintaining the healthy status of an

  1. Energy efficient of ethanol recovery in pervaporation membrane bioreactor with mechanical vapor compression eliminating the cold traps.

    PubMed

    Fan, Senqing; Xiao, Zeyi; Li, Minghai

    2016-07-01

    An energy efficient pervaporation membrane bioreactor with mechanical vapor compression was developed for ethanol recovery during the process of fermentation coupled with pervaporation. Part of the permeate vapor at the membrane downstream under the vacuum condition was condensed by running water at the first condenser and the non-condensed vapor enriched with ethanol was compressed to the atmospheric pressure and pumped into the second condenser, where the vapor was easily condensed into a liquid by air. Three runs of fermentation-pervaporation experiment have been carried out lasting for 192h, 264h and 360h respectively. Complete vapor recovery validated the novel pervaporation membrane bioreactor. The total flux of the polydimethylsiloxane (PDMS) membrane was in the range of 350gm(-2)h(-1) and 600gm(-2)h(-1). Compared with the traditional cold traps condensation, mechanical vapor compression behaved a dominant energy saving feature. PMID:26995618

  2. Dynamic mechanical response of magnesium single crystal under compression loading: Experiments, model, and simulations

    NASA Astrophysics Data System (ADS)

    Li, Qizhen

    2011-05-01

    Magnesium single crystal samples are compressed at room temperature under quasistatic (˜0.001 s-1) loading in a universal testing machine and dynamic (430, 1000, and 1200 s-1) loading in a split Hopkinson pressure bar system. Stress-strain curves show that (a) the fracture strain slightly increases with the strain rate; and (b) the maximum strength and strain hardening rate increase significantly when the testing changes from quasistatic to dynamic, although they do not vary much when the strain rate for dynamic testing varies in the range of 430-1200 s-1. The operation of the secondary pyramidal slip system is the dominating deformation mechanism, which leads to a fracture surface with an angle of ˜42° with respect to the loading axial direction. A theoretical material model based on Johnson-Cook law is also derived. The model includes the strain hardening and strain rate hardening terms, and provides the stress-strain relations matching with the experimental results. Finite element simulations for the strain rates used in the experiments predict the mechanical responses of the material that agree well with the experimental data.

  3. Chest CT Scan

    MedlinePlus

    ... pictures to create a very detailed, three-dimensional (3D) model of organs. Sometimes, a substance called contrast dye is injected into a vein in your arm for the CT scan. This substance highlights areas in your chest, which ...

  4. Chest Injuries and Disorders

    MedlinePlus

    ... your neck and your abdomen. It includes the ribs and breastbone. Inside your chest are several organs, ... and collapsed lung Pleural disorders Esophagus disorders Broken ribs Thoracic aortic aneurysms Disorders of the mediastinum, the ...

  5. Characterisation of the mechanical properties of infarcted myocardium in the rat under biaxial tension and uniaxial compression.

    PubMed

    Sirry, Mazin S; Butler, J Ryan; Patnaik, Sourav S; Brazile, Bryn; Bertucci, Robbin; Claude, Andrew; McLaughlin, Ron; Davies, Neil H; Liao, Jun; Franz, Thomas

    2016-10-01

    Understanding the passive mechanical properties of infarcted tissue at different healing stages is essential to explore the emerging biomaterial injection-based therapy for myocardial infarction (MI). Although rats have been widely used as animal models in such investigations, the data in literature that quantify the passive mechanical properties of rat heart infarcts is very limited. MI was induced in rats and hearts were harvested immediately (0 day), 7, 14 and 28 days after infarction onset. Left ventricle anterioapical samples were cut and underwent equibiaxial and non equibiaxial tension followed by uniaxial compression mechanical tests. Histological analysis was conducted to confirm MI and to quantify the size of the induced infarcts. Infarcts maintained anisotropy and the nonlinear biaxial and compressive mechanical behaviour throughout the healing phases with the circumferential direction being stiffer than the longitudinal direction. Mechanical coupling was observed between the two axes in all infarct groups. The 0, 7, 14 and 28 days infarcts showed 438, 693, 1048 and 1218kPa circumferential tensile moduli. The 28 day infarct group showed a significantly higher compressive modulus compared to the other infarct groups (p=0.0060, 0.0293, and 0.0268 for 0, 7 and 14 days groups). Collagen fibres were found to align in a preferred direction for all infarct groups supporting the observed mechanical anisotropy. The presented data are useful for developing material models for healing infarcts and for setting a baseline for future assessment of emerging mechanical-based MI therapies. PMID:27434651

  6. Mechanical behavior of twinned SiC nanowires under combined tension-torsion and compression-torsion strain

    SciTech Connect

    Li, Zhijie; Wang, Shengjie; Wang, Zhiguo; Zu, Xiaotao T.; Gao, Fei; Weber, William J.

    2010-07-01

    The mechanical behavior of twinned silicon carbide (SiC) nanowires under combined tension-torsion and compression-torsion is investigated using molecular dynamics simulations with an empirical potential. The simulation results show that both the tensile failure stress and buckling stress decrease under combined tension-torsional and combined compression-torsional strain, and they decrease with increasing torsional rate under combined loading. The torsion rate has no effect on the elastic properties of the twinned SiC nanowires. The collapse of the twinned nanowires takes place in a twin stacking fault of the nanowires.

  7. Mechanical consequences of allergic induced remodeling on mice airway resistance and compressibility.

    PubMed

    Novali, Mauro; Shalaby, Karim H; Robichaud, Annette; Benedetti, Andrea; Fereydoonzad, Liah; McGovern, Toby K; Schuessler, Thomas F; Martin, James G

    2015-11-01

    The effect of remodeling on airway function is uncertain. It may affect airway compressibility during forced expirations differently than airflow resistance, providing a tool for its assessment. The aim of the current study was to compare the effects of acute and chronic antigen challenge on methacholine-induced bronchoconstriction assessed from resistance and maximal tidal expiratory flow. Balb/C mice were sensitized with ovalbumin (OVA) and challenged either daily for three days with intra-nasal OVA or daily for 5 days and three times a week for 5 subsequent weeks. Acute and chronic allergen challenge induced airway hyperresponsiveness (AHR) to methacholine. However the relationship between maximal tidal expiratory flow and resistance during methacholine challenge was different between the two conditions, suggesting that the determinants of AHR are not identical following acute and chronic allergen exposure. We conclude that the contrast of changes in maximal tidal expiratory flow and respiratory resistance during methacholine-induced bronchoconstriction may allow the detection of the mechanical consequences of airway remodeling. PMID:26213118

  8. Strain softening mechanism at meso scale during micro-compression in an ultrafine-grained pure copper

    SciTech Connect

    Xu, Jie; Li, Jianwei; Shan, Debin; Guo, Bin

    2015-09-15

    Strain softening behavior has been found at meso scale using micro-compression testing in an ultrafine-grained (UFG) pure copper by comparison with the typical strain hardening in conventional coarse-grained (CG) material. Microstructural observations show that grain size remains nearly the same including the fraction of high-angle grain boundaries during micro-compression in UFG pure copper. The Kernel average misorientation(KAM) distribution measured by electron backscatter diffraction (EBSD), as a statistical method, is applied to qualitatively evaluate dislocation density in the interior of the grains. It is suggested that the deformation mechanisms are dominated by grain boundary sliding and grain rotation accompanied by dislocation slip in UFG pure copper, which demonstrates that the strain softening behavior is primarily caused by dislocation annihilation during micro-compression.

  9. Mechanical properties of bulk single crystalline nanoporous gold investigated by millimetre-scale tension and compression testing

    NASA Astrophysics Data System (ADS)

    Briot, Nicolas J.; Kennerknecht, Tobias; Eberl, Christoph; Balk, T. John

    2014-03-01

    In this work, the mechanical behaviour of millimetre-scale, bulk single crystalline, nanoporous gold at room temperature is reported for the first time. Tension and compression tests were performed with a custom-designed test system that accommodates small-scale samples. The absence of grain boundaries in the specimens allowed measurement of the inherent strength of millimetre-scale nanoporous gold in tension. The elastic modulus and strength values in tension and compression were found to be significantly lower than values measured with nanoindentation-based techniques and previously reported in the literature, but close to those reported for millimetre-scale polycrystalline samples tested using traditional compression techniques. Fracture toughness was found to be very low, in agreement with the macroscopic brittleness of nanoporous gold, but this is due to the localization of deformation to a narrow zone of ligaments, which individually exhibit significant plasticity and necking.

  10. Effects of Compressive Force, Particle Size and Moisture Content on Mechanical Properties of Biomass Grinds

    SciTech Connect

    Mani, Sudhagar; Tabil, Lope Jr.; Sokhansanj, Shahabaddine

    2006-03-01

    Chemical composition, moisture content, bulk and particle densities, and geometric mean particle size were determined to characterize grinds from wheat and barley straws, corn stover and switchgrass. The biomass grinds were compressed for five levels of compressive forces (1000, 2000, 3000, 4000, 4400 N) and three levels of particle sizes (3.2, 1.6 and 0.8 mm) at two levels of moisture contents (12% and 15% (wb) to establish the compression and relaxation data. Corn stover grind produced the highest compact density at low pressure during compression. Compressive force, particle size and moisture content of grinds significantly affected the compact density of barley straw, corn stover and switchgrass grinds. However, different particle sizes of wheat straw grind did not produce any significant difference on compact density. Barley straw grind had the highest asymptotic modulus among all other biomass grinds indicating that compact from barley straw grind were more rigid than those of other compacts. Asymptotic modulus increased with an increase in maximum compressive pressure. The trend of increase in asymptotic modulus (EA) with the maximum compressive pressure ( 0) was fitted to a second order polynomial equation. Keywords: Biomass grinds, chemical composition, compact density and asymptotic modulus

  11. Musculoskeletal chest wall pain

    PubMed Central

    Fam, Adel G.; Smythe, Hugh A.

    1985-01-01

    The musculoskeletal structures of the thoracic wall and the neck are a relatively common source of chest pain. Pain arising from these structures is often mistaken for angina pectoris, pleurisy or other serious disorders. In this article the clinical features, pathogenesis and management of the various musculoskeletal chest wall disorders are discussed. The more common causes are costochondritis, traumatic muscle pain, trauma to the chest wall, “fibrositis” syndrome, referred pain, psychogenic regional pain syndrome, and arthritis involving articulations of the sternum, ribs and thoracic spine. Careful analysis of the history, physical findings and results of investigation is essential for precise diagnosis and effective treatment. ImagesFig. 3Fig. 4Fig. 5 PMID:4027804

  12. A Review of Esophageal Chest Pain

    PubMed Central

    Coss-Adame, Enrique

    2015-01-01

    Noncardiac chest pain is a term that encompasses all causes of chest pain after a cardiac source has been excluded. This article focuses on esophageal sources for chest pain. Esophageal chest pain (ECP) is common, affects quality of life, and carries a substantial health care burden. The lack of a systematic approach toward the diagnosis and treatment of ECP has led to significant disability and increased health care costs for this condition. Identifying the underlying cause(s) or mechanism(s) for chest pain is key for its successful management. Common etiologies include gastroesophageal reflux disease, esophageal hypersensitivity, dysmotility, and psychological conditions, including panic disorder and anxiety. However, the pathophysiology of this condition is not yet fully understood. Randomized controlled trials have shown that proton pump inhibitor therapy (either omeprazole, lansoprazole, or rabeprazole) can be effective. Evidence for the use of antidepressants and the adenosine receptor antagonist theophylline is fair. Psychological treatments, notably cognitive behavioral therapy, may be useful in select patients. Surgery is not recommended. There remains a large unmet need for identifying the phenotype and prevalence of pathophysiologic mechanisms of ECP as well as for well-designed multicenter clinical trials of current and novel therapies. PMID:27134590

  13. A Review of Esophageal Chest Pain.

    PubMed

    Coss-Adame, Enrique; Rao, Satish S C

    2015-11-01

    Noncardiac chest pain is a term that encompasses all causes of chest pain after a cardiac source has been excluded. This article focuses on esophageal sources for chest pain. Esophageal chest pain (ECP) is common, affects quality of life, and carries a substantial health care burden. The lack of a systematic approach toward the diagnosis and treatment of ECP has led to significant disability and increased health care costs for this condition. Identifying the underlying cause(s) or mechanism(s) for chest pain is key for its successful management. Common etiologies include gastroesophageal reflux disease, esophageal hypersensitivity, dysmotility, and psychological conditions, including panic disorder and anxiety. However, the pathophysiology of this condition is not yet fully understood. Randomized controlled trials have shown that proton pump inhibitor therapy (either omeprazole, lansoprazole, or rabeprazole) can be effective. Evidence for the use of antidepressants and the adenosine receptor antagonist theophylline is fair. Psychological treatments, notably cognitive behavioral therapy, may be useful in select patients. Surgery is not recommended. There remains a large unmet need for identifying the phenotype and prevalence of pathophysiologic mechanisms of ECP as well as for well-designed multicenter clinical trials of current and novel therapies. PMID:27134590

  14. Mechanical properties and shear failure surfaces of two alumina powders in triaxial compression

    SciTech Connect

    ZEUCH,DAVID H.; GRAZIER,J. MARK; ARGUELLO JR.,JOSE G.; EWSUK,KEVIN G.

    2000-04-24

    In the manufacture of ceramic components, near-net-shape parts are commonly formed by uniaxially pressing granulated powders in rigid dies. Density gradients that are introduced into a powder compact during press-forming often increase the cost of manufacturing, and can degrade the performance and reliability of the finished part. Finite element method (FEM) modeling can be used to predict powder compaction response, and can provide insight into the causes of density gradients in green powder compacts; however, accurate numerical simulations require accurate material properties and realistic constitutive laws. To support an effort to implement an advanced cap plasticity model within the finite element framework to realistically simulate powder compaction, the authors have undertaken a project to directly measure as many of the requisite powder properties for modeling as possible. A soil mechanics approach has been refined and used to measure the pressure dependent properties of ceramic powders up to 68.9 MPa (10,000 psi). Due to the large strains associated with compacting low bulk density ceramic powders, a two-stage process was developed to accurately determine the pressure-density relationship of a ceramic powder in hydrostatic compression, and the properties of that same powder compact under deviatoric loading at the same specific pressures. Using this approach, the seven parameters that are required for application of a modified Drucker-Prager cap plasticity model were determined directly. The details of the experimental techniques used to obtain the modeling parameters and the results for two different granulated alumina powders are presented.

  15. Experimental approach and modelling of the mechanical behaviour of graphite fuel elements subjected to compression pulses

    NASA Astrophysics Data System (ADS)

    Forquin, P.

    2010-06-01

    Among the activities led by the Generation IV International Forum (GIF) relative to the future nuclear systems, the improvement of recycling of fuel elements and their components is a major issue. One of the studied systems by the GIF is the graphite-moderated high-temperature gas cooled reactor (HTGR). The fuel elements are composed of fuel roads half-inch in diameter named compacts. The compacts contain spherical particles made of actinide kernels about 500 m in diameter coated with three layers of carbon and silicon carbide, each about 50 m thick, dispersed in a graphite matrix. Recycling of compacts requires first a separation of triso-particles from the graphite matrix and secondly, the separation of the triso-coating from the kernels. This aim may be achieved by using pulsed currents: the compacts are placed within a cell filled by water and exposed to high voltage between 200 - 500 kV and discharge currents from 10 to 20 kA during short laps of time (about 2 µs) [1-2]. This repeated treatment leads to a progressive fragmentation of the graphite matrix and a disassembly of the compacts. In order to improve understanding of the fragmentation properties of compacts a series of quasi-static and dynamic experiments have been conducted with similar cylindrical samples containing 10% (volume fraction) of SiC particles coated in a graphite matrix. First, quasi-static compression tests have been performed to identify the mechanical behaviour of the material at low strain-rates (Fig.1). The experiments reveal a complex elasto-visco-plastic behaviour before a brittle failure. The mechanical response is characterised by a low yield stress (about 1 MPa), a strong strain-hardening in the loading phase and marked hysteresis-loops during unloading-reloading stages. Brittle failure is observed for axial stress about 13 MPa. In parallel, a series of flexural tests have been performed with the aim to characterise the quasi-static tensile strength of the particulate

  16. Comparative study of mechanical properties of dental restorative materials and dental hard tissues in compressive loads.

    PubMed

    Chun, Keyoung Jin; Lee, Jong Yeop

    2014-01-01

    There are two objectives. One is to show the differences in the mechanical properties of various dental restorative materials compared to those of enamel and dentin. The other is to ascertain which dental restorative materials are more suitable for clinical treatments. Amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy were processed as dental restorative material specimens. The specimens (width, height, and length of 1.2, 1.2, and 3.0 mm, respectively) were compressed at a constant loading speed of 0.1 mm/min. The maximum stress (115.0 ± 40.6, 55.0 ± 24.8, 291.2 ± 45.3, 274.6 ± 52.2, 2206.0 ± 522.9, and 953.4 ± 132.1 MPa), maximum strain (7.8% ± 0.5%, 4.0% ± 0.1%, 12.7% ± 0.8%, 32.8% ± 0.5%, 63.5% ± 14.0%, and 45.3% ± 7.4%), and elastic modulus (1437.5 ± 507.2, 1548.4 ± 583.5, 2323.4 ± 322.4, 833.1 ± 92.4, 3895.2 ± 202.9, and 2222.7 ± 277.6 MPa) were evident for amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy, respectively. The reference hardness value of amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy was 90, 420, 130-135, 86.6-124.2, 1250, and 349, respectively. Since enamel grinds food, its abrasion resistance is important. Therefore, hardness value should be prioritized for enamel. Since dentin absorbs bite forces, mechanical properties should be prioritized for dentin. The results suggest that gold alloy simultaneously has a hardness value lower than enamel (74.8 ± 18.1), which is important in the wear of the opposing natural teeth, and higher maximum stress, maximum strain, and elastic modulus than dentin (193.7 ± 30.6 MPa, 11.9% ± 0.1%, 1653.7 ± 277.9 MPa, respectively), which are important considering the rigidity to absorb bite forces. PMID:25352921

  17. Comparative study of mechanical properties of dental restorative materials and dental hard tissues in compressive loads

    PubMed Central

    Lee, Jong Yeop

    2014-01-01

    There are two objectives. One is to show the differences in the mechanical properties of various dental restorative materials compared to those of enamel and dentin. The other is to ascertain which dental restorative materials are more suitable for clinical treatments. Amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy were processed as dental restorative material specimens. The specimens (width, height, and length of 1.2, 1.2, and 3.0 mm, respectively) were compressed at a constant loading speed of 0.1 mm/min. The maximum stress (115.0 ± 40.6, 55.0 ± 24.8, 291.2 ± 45.3, 274.6 ± 52.2, 2206.0 ± 522.9, and 953.4 ± 132.1 MPa), maximum strain (7.8% ± 0.5%, 4.0% ± 0.1%, 12.7% ± 0.8%, 32.8% ± 0.5%, 63.5% ± 14.0%, and 45.3% ± 7.4%), and elastic modulus (1437.5 ± 507.2, 1548.4 ± 583.5, 2323.4 ± 322.4, 833.1 ± 92.4, 3895.2 ± 202.9, and 2222.7 ± 277.6 MPa) were evident for amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy, respectively. The reference hardness value of amalgam, dental ceramic, gold alloy, dental resin, zirconia, and titanium alloy was 90, 420, 130–135, 86.6–124.2, 1250, and 349, respectively. Since enamel grinds food, its abrasion resistance is important. Therefore, hardness value should be prioritized for enamel. Since dentin absorbs bite forces, mechanical properties should be prioritized for dentin. The results suggest that gold alloy simultaneously has a hardness value lower than enamel (74.8 ± 18.1), which is important in the wear of the opposing natural teeth, and higher maximum stress, maximum strain, and elastic modulus than dentin (193.7 ± 30.6 MPa, 11.9% ± 0.1%, 1653.7 ± 277.9 MPa, respectively), which are important considering the rigidity to absorb bite forces. PMID:25352921

  18. [Chest wall reconstruction after resection of malignant chest wall tumors].

    PubMed

    Ayabe, H; Oka, T; Akamine, S; Takahashi, T; Nagayasu, T

    1998-05-01

    Full-thickness chest wall resection is performed for complete removal of primary and secondary malignant chest wall tumors. Large defects of the chest wall after resection must be repaired to maintain adequate ventilation, to protect important intrathoracic structures, and to preserve cosmetic integrity. Various materials have been utilized over the years to replace the rigid chest wall. At present, Marlex mesh and a composite of Marlex mesh and methylmethacrylate are frequently used to reconstruct rigid chest wall defects. On the other hand, to replace the soft part of the chest wall and cover the rigid materials, pedicled muscle flaps, myocutaneous flaps, or omentum are used. Major pedicled flaps include the pectoralis major, rectus abdominis and latissimus dorsi muscular, and musculocutaneous flaps. Techniques are now available to repair any chest wall site, and to restore chest continuity in patients whose tumors are curatively resected. PMID:9656244

  19. The Protective Effects of Salubrinal on the Cartilage and Subchondral Bone of the Temporomandibular Joint under Various Compressive Mechanical Stimulations

    PubMed Central

    Zhang, Caixia; Chen, Sheng; Li, Huang

    2016-01-01

    Excessive mechanical loads on the temporomandibular joint (TMJ) can cause mandibular cartilage degradation and subchondral bone erosion, but the treatment of these conditions remains challenging. Salubrinal, which target eukaryotic translation initiation factor 2 alpha, has been shown to have multiple beneficial effects on skeletal tissue. Here, we examined the effect of a Salubrinal injection on the mandibular cartilage and subchondral bone of the TMJ under various compressive stresses. We conducted in vivo analyses in rat models using various compressive stresses (40 g and 80 g), and we observed time-related degeneration and pathological changes in the cartilage and subchondral bone of the TMJ at days 1, 3 and 7 through histological measurements, subcellular observation, and changes in proliferation and apoptosis. After the Salubrinal injection, the thickness of the cartilage recovered, and the pathological change was alleviated. In the Salubrinal/light (Sal/light) compressive stress group, the drug altered the proliferation and apoptosis of chondrocytes most significantly at day 1. In the Salubrinal/heavy (Sal/heavy) compressive stress group, the drug increased the proliferation of chondrocytes most significantly at day 1 and reduced the apoptosis of chondrocytes most significantly at day 7. Salubrinal also increased the area of the bone trabeculae and suppressed inflammatory responses and pathological change in the subchondral bone of the TMJ. Together, these results indicate that the administration of Salubrinal reduces apoptosis and strengthens the proliferation of chondrocyte to varying degrees at days 1, 3 and 7 under various compressive mechanical stresses, both of which contribute to the recovery of cartilage thickness and the alleviation of pathological change. Salubrinal also suppresses inflammatory responses and pathological change in the subchondral bone of the TMJ. PMID:27196267

  20. MRI-based inverse finite element approach for the mechanical assessment of patellar articular cartilage from static compression test.

    PubMed

    Knecht, Sven; Luechinger, Roger; Boesiger, Peter; Stüssi, Edgar

    2008-12-01

    The mechanical property of articular cartilage determines to a great extent the functionality of diarthrodial joints. Consequently, the early detection of mechanical and, thus, functional changes of cartilage is crucial for preventive measures to maintain the mobility and the quality of life of individuals. An alternative to conventional mechanical testing is the inverse finite element approach, enabling non-destructive testing of the tissue. We evaluated a method for the assessment of the equilibrium material properties of the patellar cartilage based on magnetic resonance imaging during patellofemoral compression. We performed ex vivo testing of two equine patellas with healthy cartilage, one with superficial defects, and one with synthetically degenerated cartilage to simulate a pre-osteoarthritic stage. Static compression with 400 N for 2 h resulted in morphological changes comparable to physiological in vivo deformations in humans. We observed a decrease of the equilibrium Young's modulus of the degenerated cartilage by -59%, which was in the range of the results from indentation (-74%) and confined compression tests (-58%). With the reported accuracy of magnetic resonance imaging and its reproducibility, the results indicate the potential to measure differences in Young's modulus with regard to cartilage degeneration and consequently to distinguish between healthy and pre-osteoarthritic cartilage. PMID:19037871

  1. Incidences of Deep Vein Thrombosis and Pulmonary Embolism after Total Knee Arthroplasty Using a Mechanical Compression Device with and without Low-Molecular-Weight Heparin

    PubMed Central

    Park, Sin Hyung; Ahn, Joong Hyeon; Park, Yong Bok; Lee, Sun Geun

    2016-01-01

    Purpose To investigate the incidence of thromboembolic events and complications related to bleeding after total knee arthroplasty (TKA) with a mechanical compression device alone or in combination with low-molecular-weight heparin (LMWH). Materials and Methods A total of 489 TKA patients (776 knees) were retrospectively reviewed for the incidence of thromboembolic events and complications related to bleeding. While 233 patients (354 knees) were treated with a mechanical compressive device without LMWH, 256 patients (422 knees) were treated with the mechanical compressive device along with LMWH. Results The incidences of deep vein thrombosis (DVT) and pulmonary embolism (PE) were 15 of 375 knees (4.0%) and 5 of 375 knees (1.3%), respectively, in the group that used only a mechanical compressive device, and 14 of 401 knees (3.4%) and 5 of 401 knees (1.2%), respectively, in the group that used the mechanical compressive device with LMWH. There was no significant difference between the two groups (p=0.125 and p=0.146, respectively). The postoperative hemovac drainage amount was 635±57 mL in the group with a mechanical compressive device only and 813±84 mL in the group with the device and LMWH; therefore, the amount of drainage was significantly greater in the latter group (p=0.013). Conclusions Mechanical compression alone for prophylaxis against DVT and PE after TKA can be an attractive option in Korean patients. PMID:27595075

  2. Bilateral mechanical and thermal hyperalgesia and tactile allodynia after chronic compression of dorsal root ganglion in mice.

    PubMed

    Chen, Rong-Gui; Kong, Wei-Wei; Ge, Da-Long; Luo, Ceng; Hu, San-Jue

    2011-08-01

    OBJECTIVE Low back pain is one of the most inextricable problems encountered in clinics. Animal models that imitate symptoms in humans are valuable tools for investigating low back pain mechanisms and the possible therapeutic applications. With the development of genetic technology in pain field, the possibility of mutating specific genes in mice has provided a potent tool for investigating the specific mechanisms of pain. The aim of the present study was to develop a mouse model of chronic compression of dorsal root ganglion (CCD), in which gene mutation can be applied to facilitate the studies of chronic pain. METHODS Chronic compression of L4 and L5 dorsal root ganglia was conducted in mice by inserting fine stainless steel rods into the intervertebral foramina, one at L4 and the other at L5. Mechanical allodynia and thermal hyperalgesia were examined with von Frey filaments and radiating heat stimulator, respectively. RESULTS The CCD mice displayed dramatic mechanical and thermal hyperalgesia as well as tactile allodynia in the hindpaw ipsilateral to CCD. In addition, this mechanical and thermal hyperalgesia as well as tactile allodynia was also found to spread to the contralateral hindpaw. CONCLUSION This model, combined with the possible genetic modification, will strengthen our knowledge of the underlying mechanisms of low back pain. It also favors the development of new treatment strategies for pain and hyperalgesia after spinal injury and other disorders which affect the dorsal root ganglion in humans. PMID:21788994

  3. Chest Pain (Beyond the Basics)

    MedlinePlus

    ... coronary arteries. Heart attack — A heart attack, or myocardial infarction (MI), occurs when the surface covering of a ... chest pain Criteria for the diagnosis of acute myocardial infarction Outpatient evaluation of the adult with chest pain ...

  4. Sonography of the Pediatric Chest.

    PubMed

    Goh, Yonggeng; Kapur, Jeevesh

    2016-05-01

    Traditionally, pediatric chest diseases are evaluated with chest radiography. Due to advancements in technology, the use of sonography has broadened. It has now become an established radiation-free imaging tool that may supplement plain-film findings and, in certain cases, the first-line modality for evaluation of the pediatric chest. This pictorial essay will demonstrate the diagnostic potential of sonography, review a spectrum of pediatric chest conditions, and discuss their imaging features and clinical importance. PMID:27009313

  5. Numerical study of mechanical behavior of ceramic composites under compression loading in the framework of movable cellular automaton method

    SciTech Connect

    Konovalenko, Igor S. Smolin, Alexey Yu. Konovalenko, Ivan S.; Promakhov, Vladimir V.; Psakhie, Sergey G.

    2014-11-14

    Movable cellular automaton method was used for investigating the mechanical behavior of ceramic composites under uniaxial compression. A 2D numerical model of ceramic composites based on oxides of zirconium and aluminum with different structural parameters was developed using the SEM images of micro-sections of a real composite. The influence of such structural parameters as the geometrical dimensions of layers, inclusions, and their spatial distribution in the sample, the volume content of the composite components and their mechanical properties (as well as the amount of zirconium dioxide that underwent the phase transformation) on the fracture, strength, deformation and dissipative properties was investigated.

  6. Approach to Pediatric Chest Radiograph.

    PubMed

    Jana, Manisha; Bhalla, Ashu Seith; Gupta, Arun Kumar

    2016-06-01

    Chest radiograph remains the first line imaging modality even today, especially in ICU settings. Hence proper interpretation of chest radiographs is crucial, which can be achieved by adopting a systematic approach and proper description and identification of abnormalities. In this review, the authors describe a short and comprehensive way of interpreting the pediatric chest radiograph. PMID:26983619

  7. Thermal Cycling and Degradation Mechanisms of Compressive Mica-based Seals for Solid Oxide Fuel Cells

    SciTech Connect

    Chou, Yeong-Shyung ); Stevenson, Jeffry W. )

    2002-11-14

    Thermal cycling was conducted on the compressive mica seals at 800 degrees C in air. Thin ({approx}0-1 mm) Muscovite mica was pressed between a metal pipe and an alumina substrate and tested for leak rates at a stress of 100 psi in the plain (mica only) and the hybrid design.

  8. Room temperature deformation mechanisms of alumina particles observed from in situ micro-compression and atomistic simulations.

    SciTech Connect

    Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay D.; Mook, William M.; Bufford, Daniel Charles; Boyce, Brad L.; Hattar, Khalid Mikhiel; Kotula, Paul G.; Hall, Aaron Christopher

    2015-09-22

    Aerosol deposition (AD) is a solid-state deposition technology that has been developed to fabricate ceramic coatings nominally at room temperature. Sub-micron ceramic particles accelerated by pressurized gas impact, deform, and consolidate on substrates under vacuum. Ceramic particle consolidation in AD coatings is highly dependent on particle deformation and bonding; these behaviors are not well understood. In this work, atomistic simulations and in situ micro-compressions in the scanning electron microscope, and the transmission electron microscope (TEM) were utilized to investigate fundamental mechanisms responsible for plastic deformation/fracture of particles under applied compression. Results showed that highly defective micron-sized alumina particles, initially containing numerous dislocations or a grain boundary, exhibited no observable shape change before fracture/fragmentation. Simulations and experimental results indicated that particles containing a grain boundary only accommodate low strain energy per unit volume before crack nucleation and propagation. In contrast, nearly defect-free, sub-micron, single crystal alumina particles exhibited plastic deformation and fracture without fragmentation. Dislocation nucleation/motion, significant plastic deformation, and shape change were observed. Simulation and TEM in situ micro-compression results indicated that nearly defect-free particles accommodate high strain energy per unit volume associated with dislocation plasticity before fracture. As a result, the identified deformation mechanisms provide insight into feedstock design for AD.

  9. Room temperature deformation mechanisms of alumina particles observed from in situ micro-compression and atomistic simulations.

    DOE PAGESBeta

    Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay D.; Mook, William M.; Bufford, Daniel Charles; Boyce, Brad L.; Hattar, Khalid Mikhiel; Kotula, Paul G.; Hall, Aaron Christopher

    2015-09-22

    Aerosol deposition (AD) is a solid-state deposition technology that has been developed to fabricate ceramic coatings nominally at room temperature. Sub-micron ceramic particles accelerated by pressurized gas impact, deform, and consolidate on substrates under vacuum. Ceramic particle consolidation in AD coatings is highly dependent on particle deformation and bonding; these behaviors are not well understood. In this work, atomistic simulations and in situ micro-compressions in the scanning electron microscope, and the transmission electron microscope (TEM) were utilized to investigate fundamental mechanisms responsible for plastic deformation/fracture of particles under applied compression. Results showed that highly defective micron-sized alumina particles, initially containingmore » numerous dislocations or a grain boundary, exhibited no observable shape change before fracture/fragmentation. Simulations and experimental results indicated that particles containing a grain boundary only accommodate low strain energy per unit volume before crack nucleation and propagation. In contrast, nearly defect-free, sub-micron, single crystal alumina particles exhibited plastic deformation and fracture without fragmentation. Dislocation nucleation/motion, significant plastic deformation, and shape change were observed. Simulation and TEM in situ micro-compression results indicated that nearly defect-free particles accommodate high strain energy per unit volume associated with dislocation plasticity before fracture. As a result, the identified deformation mechanisms provide insight into feedstock design for AD.« less

  10. Room Temperature Deformation Mechanisms of Alumina Particles Observed from In Situ Micro-compression and Atomistic Simulations

    NASA Astrophysics Data System (ADS)

    Sarobol, Pylin; Chandross, Michael; Carroll, Jay D.; Mook, William M.; Bufford, Daniel C.; Boyce, Brad L.; Hattar, Khalid; Kotula, Paul G.; Hall, Aaron C.

    2016-01-01

    Aerosol deposition (AD) is a solid-state deposition technology that has been developed to fabricate ceramic coatings nominally at room temperature. Sub-micron ceramic particles accelerated by pressurized gas impact, deform, and consolidate on substrates under vacuum. Ceramic particle consolidation in AD coatings is highly dependent on particle deformation and bonding; these behaviors are not well understood. In this work, atomistic simulations and in situ micro-compressions in the scanning electron microscope, and the transmission electron microscope (TEM) were utilized to investigate fundamental mechanisms responsible for plastic deformation/fracture of particles under applied compression. Results showed that highly defective micron-sized alumina particles, initially containing numerous dislocations or a grain boundary, exhibited no observable shape change before fracture/fragmentation. Simulations and experimental results indicated that particles containing a grain boundary only accommodate low strain energy per unit volume before crack nucleation and propagation. In contrast, nearly defect-free, sub-micron, single crystal alumina particles exhibited plastic deformation and fracture without fragmentation. Dislocation nucleation/motion, significant plastic deformation, and shape change were observed. Simulation and TEM in situ micro-compression results indicated that nearly defect-free particles accommodate high strain energy per unit volume associated with dislocation plasticity before fracture. The identified deformation mechanisms provide insight into feedstock design for AD.

  11. Evaluation of Quantitative Magnetic Resonance Imaging, Biochemical and Mechanical Properties of Trypsin-Treated Intervertebral Discs Under Physiological Compression Loading

    PubMed Central

    Mwale, Fackson; Demers, Caroline N.; Michalek, Arthur J.; Beaudoin, Gilles; Goswami, Tapas; Beckman, Lorne; Iatridis, James C.; Antoniou, John

    2014-01-01

    Purpose To investigate the influence of targeted trypsin digestion and 16 hours compression loading on MR parameters and the mechanical and biochemical properties of bovine disc segments. Materials and Methods Twenty-two 3-disc bovine coccygeal segments underwent compression loading for 16 hours after the nucleus pulposus (NP) of each disc was injected with a solution of trypsin or buffer. The properties of the NP and annulus fibrosus (AF) tissues of each disc were analyzed by quantitative MRI, biochemical tests, and confined compression tests. Results Loading had a significant effect on the MR properties (T1, T2, T1ρ, MTR, ADC) of both the NP and AF tissues. Loading had a greater effect on the MR parameters and biochemical composition of the NP than trypsin. In contrast, trypsin had a larger effect on the mechanical properties. Our data also indicated that localized trypsin injection predominantly affected the NP. T1ρ was sensitive to loading and correlated with the water content of the NP and AF but not with their proteoglycan content. Conclusion Our studies indicate that physiological loading is an important parameter to consider and that T1ρ contributes new information in efforts to develop quantitative MRI as a noninvasive diagnostic tool to detect changes in early disc degeneration. PMID:18219615

  12. Homicidal tandem bullet wound of the chest.

    PubMed

    Bentley, A J; Busuttil, A; Clifton, B; Sibbald, P

    1997-03-01

    An unusual case of a homicidal gunshot wound to the chest is reported in which two bullets were fired in unison as tandem bullets from a handgun. At autopsy, two intact bullets were retrieved from the body of the victim, yet there was only one entrance wound and a single bullet track across the chest wall and thoracic organs. An examination of the weapon and ammunition supported the likelihood of tandem bullets and suggested the probable mechanism for this event. Very few similar cases have been documented. PMID:9095302

  13. Age-related changes in chest geometry during cardiopulmonary resuscitation.

    PubMed

    Dean, J M; Koehler, R C; Schleien, C L; Michael, J R; Chantarojanasiri, T; Rogers, M C; Traystman, R J

    1987-06-01

    We studied alterations of chest geometry during conventional cardiopulmonary resuscitation in anesthetized immature swine. Pulsatile force was applied to the sternum in increments to determine the effects of increasing compression on chest geometry and intrathoracic vascular pressures. In 2-wk- and 1-mo-old piglets, permanent changes in chest shape developed due to incomplete recoil of the chest along the anteroposterior axis, and large intrathoracic vascular pressures were generated. In 3-mo-old animals, permanent chest deformity did not develop, and large intrathoracic vascular pressures were not produced. We propose a theoretical model of the chest as an elliptic cylinder. Pulsatile displacement along the minor axis of an ellipse produces a greater decrease in cross-sectional area than displacement of a circular cross section. As thoracic cross section became less circular due to deformity, greater changes in thoracic volume, and hence pressure, were produced. With extreme deformity at high force, pulsatile displacement became limited, diminishing pressure generation. We conclude that changes in chest geometry are important in producing intrathoracic intravascular pressure during conventional cardiopulmonary resuscitation in piglets. PMID:3610916

  14. Pediatric digital chest imaging

    SciTech Connect

    Tarver, R.D.; Cohen, M.; Broderick, N.J.; Conces, D.J. Jr. )

    1990-01-01

    The Philips Computed Radiography system performs well with pediatric portable chest radiographs, handling the throughout of a busy intensive care service 24 hours a day. Images are excellent and routinely provide a conventional (unenhanced) image and an edge-enhanced image. Radiation dose is decreased by the lowered frequency of repeat examinations and the ability of the plates to respond to a much lower dose and still provide an adequate image. The high quality and uniform density of serial PCR portable radiographs greatly enhances diagnostic content of the films. Decreased resolution has not been a problem clinically. Image manipulation and electronic transfer to remote viewing stations appear to be helpful and are currently being evaluated further. The PCR system provides a marked improvement in pediatric portable chest radiology.

  15. Filters For Chest Radiography

    NASA Astrophysics Data System (ADS)

    Ramanathan, N.; Paron, J.

    1980-08-01

    The objective of low dose radiography is achieved by a judicious combination of proper kV selection, fast film-screen systems and beam filtration. A systematic study of filters was undertaken to evaluate the improvements that can be realized in terms of patient Entrance Skin Exposures (ESE) for chest radiographs. The Picker CD 135 Generator and the Automatic Chest Filmer with dynamic phototiming were used for the study. The kV dependence of ESE with various amounts of zinc and aluminum filtration is presented. The effect of filtration on image contrast is discussed. The variations of ESE with phantom thickness under different filtration conditions are also considered. It was found that the ESE can be reduced by as much as a factor of 1.8 ± .1 with no significant increase in tube loading.

  16. Phase dependent restoration mechanisms of TC8 titanium alloy during hot compression in the two phase region

    NASA Astrophysics Data System (ADS)

    Wang, K.; Luan, B. F.; Li, M. Q.; Liu, Q.

    2015-08-01

    The TC8 titanium alloy was isothermally compressed at 1133 K and 1213 K in the (α+β) two phase region. The microstructural evolution and restoration mechanism in the α and β phases were characterized by optical microscopy and transmission electron microscopy. The results show a significant effect of phase content on the microstructural evolution and restoration mechanism. The grain refinement occurs in the α phase at both temperatures, but in the β phase only at the higher temperature of 1213 K. This difference in microstructural evolution is attributed to the different temperature dependence of restoration mechanisms in the two phases. A significant increase in the volume fraction of β phase makes the restoration mechanism in the β phase change from dynamic recovery (DRV) to dynamic recrystallization (DRX), which subsequently induces the β grain refinement.

  17. VAC® for external fixation of flail chest

    PubMed Central

    Winge, Rikke; Berg, Jais O.; Albret, Rikke; Krag, Christen

    2012-01-01

    A large aterior chest wall defect following tumor resection was reconstructed with a Gore-Tex® membrane and a combined musculocutaneous rectus femoris and tensor fasciae latae free flap. Subsequent paradoxical respiration impeded weaning from the ventilator. Appliance of Vacuum Assisted Closure® (VAC®) resulted in immediate chest wall stability and a decrease in the patient's need for respiratory support. Shortly thereafter, the VAC® was discontinued and the patient was discharged from the intensive care unit (ICU). This case report is the first to describe the successful use of VAC® as an adjuvant to a one-stage procedure for large thoracic wall reconstruction, allowing sufficient temporary external fixation to eliminate paradoxical respiration and plausibly shorten the stay in the ICU. No adverse effects on flap healing or haemodynamics were recorded. It is likely that external VAC® can improve thoracic stability and pulmonary function in a patient with flail chest and decrease the need for mechanical ventilation. PMID:24765464

  18. VAC® for external fixation of flail chest.

    PubMed

    Winge, Rikke; Berg, Jais O; Albret, Rikke; Krag, Christen

    2012-05-29

    A large aterior chest wall defect following tumor resection was reconstructed with a Gore-Tex® membrane and a combined musculocutaneous rectus femoris and tensor fasciae latae free flap. Subsequent paradoxical respiration impeded weaning from the ventilator. Appliance of Vacuum Assisted Closure® (VAC®) resulted in immediate chest wall stability and a decrease in the patient's need for respiratory support. Shortly thereafter, the VAC® was discontinued and the patient was discharged from the intensive care unit (ICU). This case report is the first to describe the successful use of VAC® as an adjuvant to a one-stage procedure for large thoracic wall reconstruction, allowing sufficient temporary external fixation to eliminate paradoxical respiration and plausibly shorten the stay in the ICU. No adverse effects on flap healing or haemodynamics were recorded. It is likely that external VAC® can improve thoracic stability and pulmonary function in a patient with flail chest and decrease the need for mechanical ventilation. PMID:24765464

  19. [Acute Chest Pain].

    PubMed

    Gmür, Christian

    2016-02-17

    Acute chest pain is a frequent consultation reason in general practice as well as in emergency departments. With the help of history, physical examination, ECG, laboratory and newly developed risk scores, potentially life-threatening diseases and high-risk patients may be detected and treated early, quickly and cost-effectively. New biomarkers and their combination with risk scores can increase the negative predictive value to exclude certain diseases. PMID:26886697

  20. A variational principle for compressible fluid mechanics. Discussion of the one-dimensional theory

    NASA Technical Reports Server (NTRS)

    Prozan, R. J.

    1982-01-01

    The second law of thermodynamics is used as a variational statement to derive a numerical procedure to satisfy the governing equations of motion. The procedure, based on numerical experimentation, appears to be stable provided the CFL condition is satisfied. This stability is manifested no matter how severe the gradients (compression or expansion) are in the flow field. For reasons of simplicity only one dimensional inviscid compressible unsteady flow is discussed here; however, the concepts and techniques are not restricted to one dimension nor are they restricted to inviscid non-reacting flow. The solution here is explicit in time. Further study is required to determine the impact of the variational principle on implicit algorithms.

  1. Accumulation of p62 in degenerated spinal cord under chronic mechanical compression

    PubMed Central

    Tanabe, Fumito; Yone, Kazunori; Kawabata, Naoya; Sakakima, Harutoshi; Matsuda, Fumiyo; Ishidou, Yasuhiro; Maeda, Shingo; Abematsu, Masahiko; Komiya, Setsuro

    2011-01-01

    Intracellular accumulation of altered proteins, including p62 and ubiquitinated proteins, is the basis of most neurodegenerative disorders. The relationship among the accumulation of altered proteins, autophagy, and spinal cord dysfunction by cervical spondylotic myelopathy has not been clarified. We examined the expression of p62 and autophagy markers in the chronically compressed spinal cord of tiptoe-walking Yoshimura mice. In addition, we examined the expression and roles of p62 and autophagy in hypoxic neuronal cells. Western blot analysis showed the accumulation of p62, ubiquitinated proteins, and microtubule-associated protein 1 light chain 3 (LC3), an autophagic marker, in the compressed spinal cord. Immunohistochemical examinations showed that p62 accumulated in neurons, axons, astrocytes, and oligodendrocytes. Electron microscopy showed the expression of autophagy markers, including autolysosomes and autophagic vesicles, in the compressed spinal cord. These findings suggest the presence of p62 and autophagy in the degenerated compressed spinal cord. Hypoxic stress increased the expression of p62, ubiquitinated proteins, and LC3-II in neuronal cells. In addition, LC3 turnover assay and GFP-LC3 cleavage assay showed that hypoxic stress increased autophagy flux in neuronal cells. These findings suggest that hypoxic stress induces accumulation of p62 and autophagy in neuronal cells. The forced expression of p62 decreased the number of neuronal cells under hypoxic stress. These findings suggest that p62 accumulation under hypoxic stress promotes neuronal cell death. Treatment with 3-methyladenine, an autophagy inhibitor decreased the number of neuronal cells, whereas lithium chloride, an autophagy inducer increased the number of cells under hypoxic stress. These findings suggest that autophagy promotes neuronal cell survival under hypoxic stress. Our findings suggest that pharmacological inducers of autophagy may be useful for treating cervical spondylotic

  2. Functional assessment of toad parotoid macroglands: a study based on poison replacement after mechanical compression.

    PubMed

    Jared, Simone G S; Jared, Carlos; Egami, Mizue I; Mailho-Fontana, Pedro L; Rodrigues, Miguel T; Antoniazzi, Marta M

    2014-09-01

    Toads have a pair of parotoid macroglands behind the eyes that secrete poison used in passive defence against predators. These macroglands are composed of juxtaposed alveoli, each one bearing a syncytial gland, all connected to the exterior by ducts. When the parotoids are bitten, the poison is expelled on the predator oral mucosa in the form of jets, causing several pharmacological actions. After poison release, the empty secretory syncytia immediately collapse in the interior of their respective alveoli and gradually start refilling. After parotoid manual compression, simulating a predator's bite, we studied, by means of morphological methods, the replacement of the poison inside the alveoli. The results showed that after compression, a considerable number of alveoli remained intact. In the alveoli that were effectively affected the recovery occurs in different levels, from total to punctual and often restrict to some areas of the syncytia. The severely affected alveoli seem not recover their original functional state. The fact that only a part of the parotoid alveoli is compressed during an attack seems to be crucial for toad survival, since the amphibian, after being bitten by a predator, do not lose all its poison stock, remaining protected in case of new attacks. PMID:24911375

  3. Microstructure and compressive mechanical properties of cortical bone in children with osteogenesis imperfecta treated with bisphosphonates compared with healthy children.

    PubMed

    Imbert, Laurianne; Aurégan, Jean-Charles; Pernelle, Kélig; Hoc, Thierry

    2015-06-01

    Osteogenesis imperfecta (OI) is a genetic disorder characterized by a change in bone tissue quality, but little data are available to describe the factors involved at the macroscopic scale. To better understand the effect of microstructure alterations on the mechanical properties at the sample scale, we studied the structural and mechanical properties of six cortical bone samples from children with OI treated with bisphosphonates and compared them to the properties of three controls. Scanning electron microscopy, high resolution computed tomography and compression testing were used to assess these properties. More resorption cavities and a higher osteocyte lacunar density were observed in OI bone compared with controls. Moreover, a higher porosity was measured for OI bones along with lower macroscopic Young's modulus, yield stress and ultimate stress. The microstructure was impaired in OI bones; the higher porosity and osteocyte lacunar density negatively impacted the mechanical properties and made the bone more prone to fracture. PMID:25828157

  4. Deformation mechanisms of olivine single crystals compressed at 300 MPa and 800-1100°C

    NASA Astrophysics Data System (ADS)

    Cordier, Patrick; Demouchy, Sylvie; Mussi, Alexandre; Tommasi, Andrea

    2013-04-01

    Rheology of mantle rocks at lithospheric temperatures remains poorly constrained, since most experimental studies on creep mechanisms of olivine single crystals ((MgFe)2SiO4, Pbnm) and polycrystalline olivine aggregates were performed at high-temperatures (T >> 1200oC). In this study, we have performed deformation experiments on oriented single crystals of San Carlos olivine and polycrystalline olivine aggregate at temperatures relevant of the uppermost mantle (ranging from 800o to 1090oC) in tri-axial compression. The experiments were carried out at a confining pressure of 300 MPa in a high-resolution gas-medium mechanical testing apparatus at various constant strain rates (from 7 × 10-6 s-1 to 1 × 10-4 s-1). Mechanical tests yield differential stresses ranging from 88 to 1076 MPa. All samples were deformed at constant displacement rate and for finite strains ranging from 4 to 23 %, to provide insight into possible effects of hardening, softening or stick-and-slip. The single crystals were compressed along several crystallographic directions to test the possibility of activating different slip systems (e.g. [100](001), [001](100), [001](010) and [100](010)). We will present the characterization of the dislocation microstructures performed in the TEM.

  5. Compression creep rupture of an E-glass/vinyl ester composite subjected to combined mechanical and fire loading conditions

    NASA Astrophysics Data System (ADS)

    Boyd, Steven Earl

    Polymer matrix composites are seeing increasing use in structural systems (e.g. ships, bridges) and require a quantitative basis for describing their performance under combined mechanical load and fire. Although much work has been performed to characterize the flammability, fire resistance and toxicity of these composite systems, an understanding of the structural response of sandwich type structures and laminate panels under combined mechanical and thermal loads (simulating fire conditions) is still largely unavailable. Therefore a research effort to develop a model to describe the structural response of these glass/vinyl esters systems under fire loading conditions is relevant to the continuing and future application of polymer matrix composites aboard naval ships. The main goal of the effort presented here is to develop analytical models and finite element analysis methods and tools to predict limit states such as local compression failures due to micro-buckling, residual strength and times to failure for composite laminates at temperatures in the vicinity of the glass transition where failure is controlled by viscoelastic effects. Given the importance of compression loading to a structure subject to fire exposure, the goals of this work are succinctly stated as the: (a) Characterization of the non-linear viscoelastic and viscoplastic response of the E-glass/vinyl ester composite above Tg. (b) Description of the laminate compression mechanics as a function of stress and temperature including viscoelasticity. (c) Viscoelastic stress analysis of a laminated panel ([0/+45/90/-45/0] S) using classical lamination theory (CLT). Three manuscripts constitute this dissertation which is representative of the three steps listed above. First, a detailed characterization of the nonlinear thermoviscoelastic response of Vetrotex 324/Derakane 510A--40 through Tg was conducted using the Time--Temperature--Stress--Superposition Principle (TTSSP) and Zapas--Crissman model. Second

  6. A Case of Traumatic Flail Chest Requiring Stabilization with Surgical Reconstruction

    PubMed Central

    Evman, Serdar; Kolbas, Ilker; Dogruyol, Talha; Tezel, Cagatay

    2015-01-01

    Background Flail chest is the most serious complication that may occur after thoracic trauma. In this article, we present a case of flail chest caused by blunt chest trauma, which presented dramatic clinical improvement following rib fixation and chest wall reconstruction. Case Description A 53-year-old male patient with flail chest because of the trauma who had been followed in intensive care unit for mechanical ventilatory support underwent chest wall stabilization with titanium reconstruction plate and screws. Conclusion The main objective is surgical stabilization of the chest wall in cases of flail chest with a parenchymal damage because of the severe rib fracture, which need prolonged mechanical ventilation. PMID:26693118

  7. Altered Knee Joint Mechanics in Simple Compression Associated with Early Cartilage Degeneration

    PubMed Central

    Dabiri, Y.; Li, L. P.

    2013-01-01

    The progression of osteoarthritis can be accompanied by depth-dependent changes in the properties of articular cartilage. The objective of the present study was to determine the subsequent alteration in the fluid pressurization in the human knee using a three-dimensional computer model. Only a small compression in the femur-tibia direction was applied to avoid numerical difficulties. The material model for articular cartilages and menisci included fluid, fibrillar and nonfibrillar matrices as distinct constituents. The knee model consisted of distal femur, femoral cartilage, menisci, tibial cartilage, and proximal tibia. Cartilage degeneration was modeled in the high load-bearing region of the medial condyle of the femur with reduced fibrillar and nonfibrillar elastic properties and increased hydraulic permeability. Three case studies were implemented to simulate (1) the onset of cartilage degeneration from the superficial zone, (2) the progression of cartilage degeneration to the middle zone, and (3) the progression of cartilage degeneration to the deep zone. As compared with a normal knee of the same compression, reduced fluid pressurization was observed in the degenerated knee. Furthermore, faster reduction in fluid pressure was observed with the onset of cartilage degeneration in the superficial zone and progression to the middle zone, as compared to progression to the deep zone. On the other hand, cartilage degeneration in any zone would reduce the fluid pressure in all three zones. The shear strains at the cartilage-bone interface were increased when cartilage degeneration was eventually advanced to the deep zone. The present study revealed, at the joint level, altered fluid pressurization and strains with the depth-wise cartilage degeneration. The results also indicated redistribution of stresses within the tissue and relocation of the loading between the tissue matrix and fluid pressure. These results may only be qualitatively interesting due to the small

  8. Chest neoplasms with infectious etiologies

    PubMed Central

    Restrepo, Carlos S; Chen, Melissa M; Martinez-Jimenez, Santiago; Carrillo, Jorge; Restrepo, Catalina

    2011-01-01

    A wide spectrum of thoracic tumors have known or suspected viral etiologies. Oncogenic viruses can be classified by the type of genomic material they contain. Neoplastic conditions found to have viral etiologies include post-transplant lymphoproliferative disease, lymphoid granulomatosis, Kaposi’s sarcoma, Castleman’s disease, recurrent respiratory papillomatosis, lung cancer, malignant mesothelioma, leukemia and lymphomas. Viruses involved in these conditions include Epstein-Barr virus, human herpes virus 8, human papillomavirus, Simian virus 40, human immunodeficiency virus, and Human T-lymphotropic virus. Imaging findings, epidemiology and mechanism of transmission for these diseases are reviewed in detail to gain a more thorough appreciation of disease pathophysiology for the chest radiologist. PMID:22224176

  9. An experimental study on fracture mechanical behavior of rock-like materials containing two unparallel fissures under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Huang, Yan-Hua; Yang, Sheng-Qi; Tian, Wen-Ling; Zeng, Wei; Yu, Li-Yuan

    2016-06-01

    Strength and deformability characteristics of rock with pre-existing fissures are governed by cracking behavior. To further research the effects of pre-existing fissures on the mechanical properties and crack coalescence process, a series of uniaxial compression tests were carried out for rock-like material with two unparallel fissures. In the present study, cement, quartz sand, and water were used to fabricate a kind of brittle rock-like material cylindrical model specimen. The mechanical properties of rock-like material specimen used in this research were all in good agreement with the brittle rock materials. Two unparallel fissures (a horizontal fissure and an inclined fissure) were created by inserting steel during molding the model specimen. Then all the pre-fissured rock-like specimens were tested under uniaxial compression by a rock mechanics servo-controlled testing system. The peak strength and Young's modulus of pre-fissured specimen all first decreased and then increased when the fissure angle increased from 0° to 75°. In order to investigate the crack initiation, propagation and coalescence process, photographic monitoring was adopted to capture images during the entire deformation process. Moreover, acoustic emission (AE) monitoring technique was also used to obtain the AE evolution characteristic of pre-fissured specimen. The relationship between axial stress, AE events, and the crack coalescence process was set up: when a new crack was initiated or a crack coalescence occurred, the corresponding axial stress dropped in the axial stress-time curve and a big AE event could be observed simultaneously. Finally, the mechanism of crack propagation under microscopic observation was discussed. These experimental results are expected to increase the understanding of the strength failure behavior and the cracking mechanism of rock containing unparallel fissures.

  10. Chronic Compression of the Dorsal Root Ganglion Enhances Mechanically Evoked Pain Behavior and the Activity of Cutaneous Nociceptors in Mice

    PubMed Central

    Wang, Tao; Hurwitz, Olivia; Shimada, Steven G.; Qu, Lintao; Fu, Kai; Zhang, Pu; Ma, Chao; LaMotte, Robert H.

    2015-01-01

    Radicular pain in humans is usually caused by intraforaminal stenosis and other diseases affecting the spinal nerve, root, or dorsal root ganglion (DRG). Previous studies discovered that a chronic compression of the DRG (CCD) induced mechanical allodynia in rats and mice, with enhanced excitability of DRG neurons. We investigated whether CCD altered the pain-like behavior and also the responses of cutaneous nociceptors with unmyelinated axons (C-fibers) to a normally aversive punctate mechanical stimulus delivered to the hairy skin of the hind limb of the mouse. The incidence of a foot shaking evoked by indentation of the dorsum of foot with an aversive von Frey filament (tip diameter 200 μm, bending force 20 mN) was significantly higher in the foot ipsilateral to the CCD surgery as compared to the contralateral side on post-operative days 2 to 8. Mechanically-evoked action potentials were electrophysiologically recorded from the L3 DRG, in vivo, from cell bodies visually identified as expressing a transgenically labeled fluorescent marker (neurons expressing either the receptor MrgprA3 or MrgprD). After CCD, 26.7% of MrgprA3+ and 32.1% MrgprD+ neurons exhibited spontaneous activity (SA), while none of the unoperated control neurons had SA. MrgprA3+ and MrgprD+ neurons in the compressed DRG exhibited, in comparison with neurons from unoperated control mice, an increased response to the punctate mechanical stimuli for each force applied (6, 20, 40, and 80 mN). We conclude that CCD produced both a behavioral hyperalgesia and an enhanced response of cutaneous C-nociceptors to aversive punctate mechanical stimuli. PMID:26356638

  11. Dynamic characteristics and mechanisms of compressible metallic vapor plume behaviors in transient keyhole during deep penetration fiber laser welding

    NASA Astrophysics Data System (ADS)

    Pang, Shengyong; Shao, Xinyu; Li, Wen; Chen, Xin; Gong, Shuili

    2016-07-01

    The compressible metallic vapor plume or plasma plume behaviors in the keyhole during deep penetration laser welding have significant effects on the joint quality. However, these behaviors and their responses to process parameter variations have not been well understood. In this paper, we first systematically study the dynamic characteristics and mechanisms of compressible metallic vapor plume behaviors in transient keyhole during fiber laser welding of 304 stainless steels based on a multiple timescale multiphase model. The time-dependent temperature, pressure, velocity and Mach number distributions of vapor plume under different process parameters are theoretically predicted. It is found that the distributions of the main physical characteristics of vapor plume such as pressure, velocity as well as Mach number in keyhole are usually highly uneven and highly time dependent. The peak difference of the velocity, pressure, temperature and Mach number of the vapor plume in a keyhole could be greater than 200 m/s, 20 kPa, 1000 K and 0.6 Mach, respectively. The vapor plume characteristics in a transient keyhole can experience significant changes within several hundreds of nanoseconds. The formation mechanisms of these dynamic characteristics are mainly due to the mesoscale keyhole hump (sized in several tens of microns) dynamics. It is also demonstrated that it is possible to suppress the oscillations of compressible vapor plume in the keyhole by improving the keyhole stability through decreasing the heat input. However, stabilizing the keyhole could only weaken, but not eliminate, the observed highly uneven and transient characteristics. This finding may pose new challenges for accurate experimental measurements of vapor plume induced by laser welding.

  12. Melt-based compression-molded scaffolds from chitosan-polyester blends and composites: Morphology and mechanical properties.

    PubMed

    Correlo, V M; Boesel, L F; Pinho, E; Costa-Pinto, A R; Alves da Silva, M L; Bhattacharya, M; Mano, J F; Neves, N M; Reis, R L

    2009-11-01

    Blends of chitosan and synthetic aliphatic polyesters (polybutylene succinate, polybutylene succinate adipate, polycaprolactone, and polybutylene terepthalate adipate) were compounded with and without hydroxyapatite, a bioactive mineral filler known to enhance osteoconduction. The blends and composites were compression molded with two different granulometric salt sizes (63-125 microm and 250-500 microm) having different levels of salt content (60, 70, and 80%) by weight. By leaching the salt particles, it was possible to produce porous scaffolds with distinct morphologies. The relationship between scaffold morphology and mechanical properties was evaluated using scanning electron microscopy, microcomputed tomography, compression testing, differential scanning calorimetry, small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering. The produced scaffolds are characterized by having different morphologies depending on the average particle size and the amount of NaCl used. Specimens with higher porosity level have a less organized pore structure but increased interconnectivity of the pores. The stress-strain curve under compression displayed a linear elasticity followed by a plateau whose characteristics depend on the scaffold polymer composition. A decrease in the salt particle size used to create the porosity caused in general a decrease in the mechanical properties of the foams. Composites with hydroxyapatite had a sharp reduction in yield stress, modulus, and strain at break. The melting temperature decreased with increased chitosan content. SAXS results indicate no preferential crystalline orientation in the scaffolds. Cytotoxicity evaluation were carried out using standard tests (accordingly to ISO/EN 10993 part 5 guidelines), namely MTS test with a 24-h extraction period, revealing that L929 cells had comparable metabolic activities to that obtained for the negative control. PMID:18985771

  13. Experimental and Numerical Study on the Deformation Mechanism in AZ31B Mg Alloy Sheets Under Pulsed Electric-Assisted Tensile and Compressive Tests

    NASA Astrophysics Data System (ADS)

    Lee, Jinwoo; Kim, Se-Jong; Lee, Myoung-Gyu; Song, Jung Han; Choi, Seogou; Han, Heung Nam; Kim, Daeyong

    2016-06-01

    The uniaxial tensile and compressive stress-strain responses of AZ31B magnesium alloy sheet under pulsed electric current are reported. Tension and compression tests with pulsed electric current showed that flow stresses dropped instantaneously when the electric pulses were applied. Thermo-mechanical-electrical finite element analyses were also performed to investigate the effects of Joule heating and electro-plasticity on the flow responses of AZ31B sheets under electric-pulsed tension and compression tests. The proposed finite element simulations could reproduce the measured uniaxial tensile and compressive stress-strain curves under pulsed electric currents, when the temperature-dependent flow stress hardening model and thermal properties of AZ31B sheet were properly described in the simulations. In particular, the simulation results that fit best with experimental results showed that almost 100 pct of the electric current was subject to transform into Joule heating during electrically assisted tensile and compressive tests.

  14. Experimental and Numerical Study on the Deformation Mechanism in AZ31B Mg Alloy Sheets Under Pulsed Electric-Assisted Tensile and Compressive Tests

    NASA Astrophysics Data System (ADS)

    Lee, Jinwoo; Kim, Se-Jong; Lee, Myoung-Gyu; Song, Jung Han; Choi, Seogou; Han, Heung Nam; Kim, Daeyong

    2016-04-01

    The uniaxial tensile and compressive stress-strain responses of AZ31B magnesium alloy sheet under pulsed electric current are reported. Tension and compression tests with pulsed electric current showed that flow stresses dropped instantaneously when the electric pulses were applied. Thermo-mechanical-electrical finite element analyses were also performed to investigate the effects of Joule heating and electro-plasticity on the flow responses of AZ31B sheets under electric-pulsed tension and compression tests. The proposed finite element simulations could reproduce the measured uniaxial tensile and compressive stress-strain curves under pulsed electric currents, when the temperature-dependent flow stress hardening model and thermal properties of AZ31B sheet were properly described in the simulations. In particular, the simulation results that fit best with experimental results showed that almost 100 pct of the electric current was subject to transform into Joule heating during electrically assisted tensile and compressive tests.

  15. Static compressive strength prediction of open-hole structure based on non-linear shear behavior and micro-mechanics

    NASA Astrophysics Data System (ADS)

    Li, Wangnan; Cai, Hongneng; Li, Chao

    2014-11-01

    This paper deals with the characterization of the strength of the constituents of carbon fiber reinforced plastic laminate (CFRP), and a prediction of the static compressive strength of open-hole structure of polymer composites. The approach combined with non-linear analysis in macro-level and a linear elastic micromechanical failure analysis in microlevel (non-linear MMF) is proposed to improve the prediction accuracy. A face-centered cubic micromechanics model is constructed to analyze the stresses in fiber and matrix in microlevel. Non-interactive failure criteria are proposed to characterize the strength of fiber and matrix. The non-linear shear behavior of the laminate is studied experimentally, and a novel approach of cubic spline interpolation is used to capture significant non-linear shear behavior of laminate. The user-defined material subroutine UMAT for the non-linear share behavior is developed and combined in the mechanics analysis in the macro-level using the Abaqus Python codes. The failure mechanism and static strength of open-hole compressive (OHC) structure of polymer composites is studied based on non-linear MMF. The UTS50/E51 CFRP is used to demonstrate the application of theory of non-linear MMF.

  16. Strength and Mechanical Response of NaCl Using In-Situ Transmission Electron Microscopy Compression and Nanoindentation.

    PubMed

    Lin, Kai-Peng; Fang, Te-Hua; Kang, Sho-Hui

    2016-03-01

    Strength and mechanical properties of single crystal sodium chloride (NaCl) are characterized. Critical deformation variations of NaCl pillared structures and films are estimated using in-situ transmission electron microscope (TEM) compression tests and nanoindentation experiments. Young's modulus and contact stiffness of NaCl pillars with diameters of 300 to 500 nm were 10.4-23.9 GPa, and 159-230 N/m, respectively. The nanohardness and Vickers hardness of the NaCl (001) film were 282-596 and 196-260 MPa, respectively. The results could provide useful information for understanding the mechanical properties, contact and local deformation of NaCl pillars and films. PMID:27455676

  17. Supercharged two-cycle engines employing novel single element reciprocating shuttle inlet valve mechanisms and with a variable compression ratio

    NASA Technical Reports Server (NTRS)

    Wiesen, Bernard (Inventor)

    2008-01-01

    This invention relates to novel reciprocating shuttle inlet valves, effective with every type of two-cycle engine, from small high-speed single cylinder model engines, to large low-speed multiple cylinder engines, employing spark or compression ignition. Also permitting the elimination of out-of-phase piston arrangements to control scavenging and supercharging of opposed-piston engines. The reciprocating shuttle inlet valve (32) and its operating mechanism (34) is constructed as a single and simple uncomplicated member, in combination with the lost-motion abutments, (46) and (48), formed in a piston skirt, obviating the need for any complex mechanisms or auxiliary drives, unaffected by heat, friction, wear or inertial forces. The reciprocating shuttle inlet valve retains the simplicity and advantages of two-cycle engines, while permitting an increase in volumetric efficiency and performance, thereby increasing the range of usefulness of two-cycle engines into many areas that are now dominated by the four-cycle engine.

  18. Classification of chest wall diseases.

    PubMed

    Pozzi, E; Gulotta, C

    1993-01-01

    Several disorders of the thoracic cage are known to cause respiratory failure, by means of relatively simple mechanisms, such as the increased work of breathing, which results in alveolar hypoventilation. A variety of pathogenic mechanisms may be considered, as functions of the types of thoracic disorders present. As causes of these additional potential mechanisms, we considered the following: 1) ventilation-perfusion (V/Q) inhomogeneity; 2) inability to cough; 3) malformation or acquired defect of the respiratory centres; and 4) excess blood volume and fluid retention, which aggravate work of breathing and V/Q inhomogeneity. All of these disorders can be grouped into two major categories (which nevertheless have some of the pathophysiology in common): the mechanical syndrome and the neuromuscular or paralytic syndrome. In this paper we discuss chest wall diseases falling into the first category; namely, kyphoscoliosis, fibrothorax, thoracoplasty, ankylosing spondylitis and obesity-hypoventilation. Congenital deformities of the thoracic cage, which do not have important effects on ventilatory apparatus (e.g. pectus excavatum and pectus carinatum), were also considered. PMID:8472068

  19. Mechanical properties of GFRP tube confined recycled concrete under axial compression

    NASA Astrophysics Data System (ADS)

    Wang, Xiaogang; Liang, Chaofeng; Zhou, Zechenglong; Dong, Lanqi; Ding, Kewei; Huang, Jialun

    2015-07-01

    This article outlines the recycled aggregate replacement rate and thick-diameter rate of GFRP tube confined in recycled concrete, which has an important impact on the material's compressive strength. Overall, under the same conditions of using recycled concrete, the bearing capacity of short concrete columns can be improved by using broader GFRP tubes. There is a four-fold increase in the bearing capacity of short concrete columns compared to the short column without the restriction of a GFRP tube. The bearing capacity of a short column crafted by recycled coarse aggregate is much lower (about 30%). than those made by common concrete column Additionally, the bearing capacity of short columns made by recycled fine aggregates is also lower than those made by common concrete (approximately 20%). Finally, we find that there is no significant difference between experimental and theoretical data.

  20. Triptans and chest symptoms: the role of pulmonary vasoconstriction.

    PubMed

    Dodick, D W

    2004-04-01

    Triptans are effective and well tolerated in the treatment of acute migraine. Chest symptoms are a common adverse effect unrelated to coronary vasoconstriction in most patients. Although the aetiology of chest symptoms remains to be fully defined, pulmonary vasoconstriction is a possible underlying mechanism. Pre-clinical studies of isolated human blood vessels were used to identify the cerebral selectivity of triptans and ascertain if selectivity vs the pulmonary vasculature predicts a lower rate of chest symptoms. Controlled clinical trials and post-marketing surveillance studies were reviewed to document the incidence of chest symptoms after triptan therapy. In clinical trials, the incidence of chest symptoms at usual therapeutic doses ranged from 1 to 4% depending on the triptan and study design, whereas in post-marketing surveillance studies, up to 41% of patients specifically asked about chest symptoms reported them. A comparative clinical trial showed that almotriptan was associated with lower incidence of chest symptoms than sumatriptan (0.3 vs 2.2%). The intrinsic activity of almotriptan, a second-generation triptan, on human pulmonary arteries and veins was lower than that of sumatriptan. Pre-clinical studies of isolated pulmonary blood vessels may predict the clinical likelihood of chest symptoms; however, additional comparisons are needed. PMID:15030540

  1. Experimental characterization and constitutive modeling of the mechanical behavior of molybdenum under electromagnetically applied compression-shear ramp loading

    NASA Astrophysics Data System (ADS)

    Alexander, C. S.; Ding, J. L.; Asay, J. R.

    2016-03-01

    Magnetically applied pressure-shear (MAPS) is a new experimental technique that provides a platform for direct measurement of material strength at extreme pressures. The technique employs an imposed quasi-static magnetic field and a pulsed power generator that produces an intense current on a planar driver panel, which in turn generates high amplitude magnetically induced longitudinal compression and transverse shear waves into a planar sample mounted on the drive panel. In order to apply sufficiently high shear traction to the test sample, a high strength material must be used for the drive panel. Molybdenum is a potential driver material for the MAPS experiment because of its high yield strength and sufficient electrical conductivity. To properly interpret the results and gain useful information from the experiments, it is critical to have a good understanding and a predictive capability of the mechanical response of the driver. In this work, the inelastic behavior of molybdenum under uniaxial compression and biaxial compression-shear ramp loading conditions is experimentally characterized. It is observed that an imposed uniaxial magnetic field ramped to approximately 10 T through a period of approximately 2500 μs and held near the peak for about 250 μs before being tested appears to anneal the molybdenum panel. In order to provide a physical basis for model development, a general theoretical framework that incorporates electromagnetic loading and the coupling between the imposed field and the inelasticity of molybdenum was developed. Based on this framework, a multi-axial continuum model for molybdenum under electromagnetic loading is presented. The model reasonably captures all of the material characteristics displayed by the experimental data obtained from various experimental configurations. In addition, data generated from shear loading provide invaluable information not only for validating but also for guiding the development of the material model for

  2. Experimental characterization and constitutive modeling of the mechanical behavior of molybdenum under electromagnetically applied compression-shear ramp loading

    DOE PAGESBeta

    Alexander, C. Scott; Ding, Jow -Lian; Asay, James Russell

    2016-03-09

    Magnetically applied pressure-shear (MAPS) is a new experimental technique that provides a platform for direct measurement of material strength at extreme pressures. The technique employs an imposed quasi-static magnetic field and a pulsed power generator that produces an intense current on a planar driver panel, which in turn generates high amplitude magnetically induced longitudinal compression and transverse shear waves into a planar sample mounted on the drive panel. In order to apply sufficiently high shear traction to the test sample, a high strength material must be used for the drive panel. Molybdenum is a potential driver material for the MAPSmore » experiment because of its high yield strength and sufficient electrical conductivity. To properly interpret the results and gain useful information from the experiments, it is critical to have a good understanding and a predictive capability of the mechanical response of the driver. In this work, the inelastic behavior of molybdenum under uniaxial compression and biaxial compression-shear ramp loading conditions is experimentally characterized. It is observed that an imposed uniaxial magnetic field ramped to approximately 10 T through a period of approximately 2500 μs and held near the peak for about 250 μs before being tested appears to anneal the molybdenum panel. In order to provide a physical basis for model development, a general theoretical framework that incorporates electromagnetic loading and the coupling between the imposed field and the inelasticity of molybdenum was developed. Based on this framework, a multi-axial continuum model for molybdenum under electromagnetic loading is presented. The model reasonably captures all of the material characteristics displayed by the experimental data obtained from various experimental configurations. Additionally, data generated from shear loading provide invaluable information not only for validating but also for guiding the development of the material

  3. A mechanistic insight into the mechanical role of the stratum corneum during stretching and compression of the skin.

    PubMed

    Leyva-Mendivil, Maria F; Page, Anton; Bressloff, Neil W; Limbert, Georges

    2015-09-01

    The study of skin biophysics has largely been driven by consumer goods, biomedical and cosmetic industries which aim to design products that efficiently interact with the skin and/or modify its biophysical properties for health or cosmetic benefits. The skin is a hierarchical biological structure featuring several layers with their own distinct geometry and mechanical properties. Up to now, no computational models of the skin have simultaneously accounted for these geometrical and material characteristics to study their complex biomechanical interactions under particular macroscopic deformation modes. The goal of this study was, therefore, to develop a robust methodology combining histological sections of human skin, image-processing and finite element techniques to address fundamental questions about skin mechanics and, more particularly, about how macroscopic strains are transmitted and modulated through the epidermis and dermis. The work hypothesis was that, as skin deforms under macroscopic loads, the stratum corneum does not experience significant strains but rather folds/unfolds during skin extension/compression. A sample of fresh human mid-back skin was processed for wax histology. Sections were stained and photographed by optical microscopy. The multiple images were stitched together to produce a larger region of interest and segmented to extract the geometry of the stratum corneum, viable epidermis and dermis. From the segmented structures a 2D finite element mesh of the skin composite model was created and geometrically non-linear plane-strain finite element analyses were conducted to study the sensitivity of the model to variations in mechanical properties. The hybrid experimental-computational methodology has offered valuable insights into the simulated mechanics of the skin, and that of the stratum corneum in particular, by providing qualitative and quantitative information on strain magnitude and distribution. Through a complex non-linear interplay

  4. Compressed gas manifold

    DOEpatents

    Hildebrand, Richard J.; Wozniak, John J.

    2001-01-01

    A compressed gas storage cell interconnecting manifold including a thermally activated pressure relief device, a manual safety shut-off valve, and a port for connecting the compressed gas storage cells to a motor vehicle power source and to a refueling adapter. The manifold is mechanically and pneumatically connected to a compressed gas storage cell by a bolt including a gas passage therein.

  5. Comparison of the Mechanical Characteristics of a Universal Small Biplane Plating Technique Without Compression Screw and Single Anatomic Plate With Compression Screw.

    PubMed

    Dayton, Paul; Ferguson, Joe; Hatch, Daniel; Santrock, Robert; Scanlan, Sean; Smith, Bret

    2016-01-01

    To better understand the mechanical characteristics of biplane locked plating in small bone fixation, the present study compared the stability under cyclic cantilever loading of a 2-plate locked biplane (BPP) construct without interfragmentary compression with that of a single-plate locked construct with an additional interfragmentary screw (SPS) using surrogate bone models simulating Lapidus arthrodesis. In static ultimate plantar bending, the BPP construct failed at significantly greater load than did the SPS construct (556.2 ± 37.1 N versus 241.6 ± 6.3 N, p = .007). For cyclic failure testing in plantar bending at a 180-N starting load, the BPP construct failed at a significantly greater number of cycles (158,322 ± 50,609 versus 13,718 ± 10,471 cycles) and failure load (242.5 ± 25.0 N versus 180.0 ± 0.0 N) than the SPS construct (p = .002). For cyclic failure testing in plantar bending at a 120-N starting load, the results were not significantly different between the BPP and SPS constructs for the number of cycles (207,646 ± 45,253 versus 159,334 ± 69,430) or failure load (205.0 ± 22.4 N versus 185.0 ± 33.5 N; p = .300). For cyclic testing with 90° offset loading (i.e., medial to lateral bending) at a 120-N starting load, all 5 BPP constructs (tension side) and 2 of the 5 SPS constructs reached 250,000 cycles without failure. Overall, the present study found the BPP construct to have superior or equivalent stability in multiplanar orientations of force application in both static and fatigue testing. Thus, the concept of biplane locked plating, using 2 low profile plates and unicortical screw insertion, shows promise in small bone fixation, because it provides consistent stability in multiplanar orientations, making it universally adaptable to many clinical situations. PMID:26872521

  6. Mechanical and electronic-structure properties of compressed CdSetetrapod nanocrystals

    SciTech Connect

    Schrier, Joshua; Lee, Byounghak; Wang, Lin-Wang

    2007-01-18

    The coupling of mechanical and optical properties insemiconductor nanostructures can potentially lead to new types ofdevices. This work describes our theoretical examination of themechanical properties of CdSe tetrapods under directional forces, such asmay be induced by AFM tips. In addition to studying the general behaviorof the mechanical properties under modifications of geometry,nanocrystal-substrate interaction, and dimensional scaling, ourcalculations indicate that mechanical deformations do not lead to largechanges in the band-edge state eigenenergies, and have only a weak effecton the oscillator strengths of the lowest energy transitions.

  7. On the initiation of shear faults during brittle compressive failure: A new mechanism

    NASA Astrophysics Data System (ADS)

    Schulson, Erland M.; Iliescu, Daniel; Renshaw, Carl E.

    1999-01-01

    Brittle materials loaded under compression generally fail by shear faulting. This paper addresses the initiation of the fault. It presents direct observational evidence from ice, which is used as a model material for rock, and shows that wing cracking and "splay cracking" are important processes in the localization of deformation, both prior to and during fault initiation. Wing cracks develop at the tips of sliding intergranular cracks and tend to align with the maximum principal stress. Splay cracks emanate from one side of the sliding parent crack. The theme of the paper is that the splay cracks play the dominant role in triggering the fault. The central idea is that the slender columns between the splay cracks are more likely to buckle and fail than are the columns between adjacent wing cracks because they do not have two fixed ends; instead, the end stemming from the inclined parent crack is free. A moment is then applied by frictional sliding of the parent inclined crack, and this causes the fixed-free columns to break at a much lower stress than the fixed-fixed columns. Columns created near a free surface are more likely to fail than those created elsewhere, and this explains the observation that shear localization tends to initiate near free surfaces. A first-order calculation shows that the failure stress of the splay-created columns is of the same order of magnitude as the terminal failure stress.

  8. On the mechanism of buckling of a circular cylindrical shell under axial compression

    NASA Technical Reports Server (NTRS)

    Yoshimura, Yoshimaru

    1955-01-01

    The present paper deals with the buckling of a circular cylindrical shell under axial compression from the viewpoint of energy and the characteristics of deformation. It is shown first, both theoretically and experimentally, that the reason why the buckling of a cylindrical shell is quite different from that of a flat plate is attributable to the existence of a nearly developable surface far apart from the original cylindrical surface. Based upon this result, the experimental fact that the buckling is really not general but local, that is, that the buckled region is limited axially to a range of 1.5 times the wave length of the lobe, is explained by the theoretical result that the minimum buckling load is smaller in the local buckling than in the general buckling case. The occurrence of local buckling is affirmed also from the viewpoint of the energy barrier to be jumped over during buckling, and from a comparison of the theoretical post-buckling state with the experimental results. Finally, the local buckling with the load applied by a spring is analyzed, and it is proved that the minimum buckling load increased with an increase of rigidity of the spring.

  9. A conservative approximation to compressible two-phase flow models in the stiff mechanical relaxation limit

    SciTech Connect

    Deledicque, Vincent; Papalexandris, Miltiadis V.

    2008-11-10

    In this article, we present and analyze a conservative approximation to reduced one-pressure one-velocity models for compressible two-phase flows that contain non-conservative products. This approximation is valid when certain material properties of the two phases are considerably different from each other. Although it cannot be applied to arbitrary mixtures, it is applicable to many heterogeneous mixtures of technological interest. Herein, we derive the Rankine-Hugoniot relations and Riemann invariants for the homogeneous part of the proposed model and develop an exact Riemann solver for it. Further, we investigate the structure of the steady two-phase detonation waves, with inert or reactive solid particles, admitted by the proposed model. Comparisons with the corresponding gaseous detonations are also made. Moreover, we derive a lower limit for the propagation speed of steady two-phase detonations in the case of reactive particles. At the limiting case of very dilute mixtures, this minimum speed tends to the Chapman-Jouguet velocity of gaseous detonations. Finally, we report on numerical simulations of the transmission of a purely gaseous detonation to heterogeneous mixtures containing inert or reactive solid particles. The effect of the solid particles on the structure of the resulting two-phase detonation is discussed in detail.

  10. Mechanical testing of hydrogels in cartilage tissue engineering: beyond the compressive modulus.

    PubMed

    Xiao, Yinghua; Friis, Elizabeth A; Gehrke, Stevin H; Detamore, Michael S

    2013-10-01

    Injuries to articular cartilage result in significant pain to patients and high medical costs. Unfortunately, cartilage repair strategies have been notoriously unreliable and/or complex. Biomaterial-based tissue-engineering strategies offer great promise, including the use of hydrogels to regenerate articular cartilage. Mechanical integrity is arguably the most important functional outcome of engineered cartilage, although mechanical testing of hydrogel-based constructs to date has focused primarily on deformation rather than failure properties. In addition to deformation testing, as the field of cartilage tissue engineering matures, this community will benefit from the addition of mechanical failure testing to outcome analyses, given the crucial clinical importance of the success of engineered constructs. However, there is a tremendous disparity in the methods used to evaluate mechanical failure of hydrogels and articular cartilage. In an effort to bridge the gap in mechanical testing methods of articular cartilage and hydrogels in cartilage regeneration, this review classifies the different toughness measurements for each. The urgency for identifying the common ground between these two disparate fields is high, as mechanical failure is ready to stand alongside stiffness as a functional design requirement. In comparing toughness measurement methods between hydrogels and cartilage, we recommend that the best option for evaluating mechanical failure of hydrogel-based constructs for cartilage tissue engineering may be tensile testing based on the single edge notch test, in part because specimen preparation is more straightforward and a related American Society for Testing and Materials (ASTM) standard can be adopted in a fracture mechanics context. PMID:23448091

  11. Compressive properties of commercially available polyurethane foams as mechanical models for osteoporotic human cancellous bone

    PubMed Central

    Patel, Purvi SD; Shepherd, Duncan ET; Hukins, David WL

    2008-01-01

    Background Polyurethane (PU) foam is widely used as a model for cancellous bone. The higher density foams are used as standard biomechanical test materials, but none of the low density PU foams are universally accepted as models for osteoporotic (OP) bone. The aim of this study was to determine whether low density PU foam might be suitable for mimicking human OP cancellous bone. Methods Quasi-static compression tests were performed on PU foam cylinders of different lengths (3.9 and 7.7 mm) and of different densities (0.09, 0.16 and 0.32 g.cm-3), to determine the Young's modulus, yield strength and energy absorbed to yield. Results Young's modulus values were 0.08–0.93 MPa for the 0.09 g.cm-3 foam and from 15.1–151.4 MPa for the 0.16 and 0.32 g.cm-3 foam. Yield strength values were 0.01–0.07 MPa for the 0.09 g.cm-3 foam and from 0.9–4.5 MPa for the 0.16 and 0.32 g.cm-3 foam. The energy absorbed to yield was found to be negligible for all foam cylinders. Conclusion Based on these results, it is concluded that 0.16 g.cm-3 PU foam may prove to be suitable as an OP cancellous bone model when fracture stress, but not energy dissipation, is of concern. PMID:18844988

  12. Investigation on Mechanical Behaviors of Sandstone with Two Preexisting Flaws under Triaxial Compression

    NASA Astrophysics Data System (ADS)

    Huang, Da; Gu, Dongming; Yang, Chao; Huang, Runqiu; Fu, Guoyang

    2016-02-01

    Triaxial compression experiments on sandstone samples with two preexisting closed non-overlapping flaws were performed to investigate the deformation and strength behaviors. Three types of preexisting closed flaw pair in sandstone samples, i.e., parallel low-dip (type B), parallel high-dip (type C), and composite high- and low-dip (type D), were considered as the typical arrangements of the non-overlapping crack pair. A general rule has been found that the arrangement of the flaw pair has greater impact on the rock deformation, strength, and crack coalescence pattern than the confining pressure (5-20 MPa). Experimental results showed that, compared with intact sandstone samples, the postpeak stress-strain curves of flawed samples distinctly demonstrate stress fluctuation. In particular, the unique prepeak stress-strain curves of the specimens with a low-dip flaw pair (type B) present oblique Z-shape with a double-peak stress. The stress for crack initiation σ ci, the critical stress of dilation σ cd, and the peak strength σ c of precracked sandstone samples are significantly lower than those of intact rock. The present numerical study, which is an extension of the test analysis, focuses on identifying the crack nature (tensile or shear) and coalescence process. These simulated crack coalescence patterns are in good agreement with the laboratory test results. The cracks of the precracked samples that contained flaws with small inclination angle (associated with either type B or type D) generally initiate at the inner flaw tips and eventually lead to simple direct shear coalescence. However, complex indirect shear coalescence appears in the model containing a steep preexisting flaw pair (associated with type B specimen), even though no coalescence occurs when σ 3 = 5 MPa.

  13. Mechanical Properties and Microstructure of the CoCrFeMnNi High Entropy Alloy Under High Strain Rate Compression

    NASA Astrophysics Data System (ADS)

    Wang, Bingfeng; Fu, Ao; Huang, Xiaoxia; Liu, Bin; Liu, Yong; Li, Zezhou; Zan, Xiang

    2016-07-01

    The equiatomic CoCrFeMnNi high entropy alloy, which crystallizes in the face-centered cubic (FCC) crystal structure, was prepared by the spark plasma sintering technique. Dynamic compressive tests of the CoCrFeMnNi high entropy alloy were deformed at varying strain rates ranging from 1 × 103 to 3 × 103 s-1 using a split-Hopkinson pressure bar (SHPB) system. The dynamic yield strength of the CoCrFeMnNi high entropy alloy increases with increasing strain rate. The Zerilli-Armstrong (Z-A) plastic model was applied to model the dynamic flow behavior of the CoCrFeMnNi high entropy alloy, and the constitutive relationship was obtained. Serration behavior during plastic deformation was observed in the stress-strain curves. The mechanism for serration behavior of the alloy deformed at high strain rate is proposed.

  14. Mechanical Properties and Microstructure of the CoCrFeMnNi High Entropy Alloy Under High Strain Rate Compression

    NASA Astrophysics Data System (ADS)

    Wang, Bingfeng; Fu, Ao; Huang, Xiaoxia; Liu, Bin; Liu, Yong; Li, Zezhou; Zan, Xiang

    2016-05-01

    The equiatomic CoCrFeMnNi high entropy alloy, which crystallizes in the face-centered cubic (FCC) crystal structure, was prepared by the spark plasma sintering technique. Dynamic compressive tests of the CoCrFeMnNi high entropy alloy were deformed at varying strain rates ranging from 1 × 103 to 3 × 103 s-1 using a split-Hopkinson pressure bar (SHPB) system. The dynamic yield strength of the CoCrFeMnNi high entropy alloy increases with increasing strain rate. The Zerilli-Armstrong (Z-A) plastic model was applied to model the dynamic flow behavior of the CoCrFeMnNi high entropy alloy, and the constitutive relationship was obtained. Serration behavior during plastic deformation was observed in the stress-strain curves. The mechanism for serration behavior of the alloy deformed at high strain rate is proposed.

  15. FEM analysis of deformation localization mechanisms in a 3-D fractured medium under rotating compressive stress orientations

    NASA Astrophysics Data System (ADS)

    Strijker, Geertje; Beekman, Fred; Bertotti, Giovanni; Luthi, Stefan M.

    2013-05-01

    Stress distributions and deformation patterns in a medium with a pre-existing fracture set are analyzed as a function of the remote compressive stress orientation (σH) using finite element models with increasingly complex fracture configurations. Slip along the fractures causes deformation localization at the tips as wing cracks or shear zones. The deformation intensity is proportional to the amount of slip, attaining a peak value for α = 45° (α: angle between the fracture strike and σH) and slip is linearly proportional with fracture length. Wing cracks develop for high deformation intensities for 30° < α < 60°, whereas primary plastic shear zones develop for low deformation intensities. Additionally, two types of secondary shear zones develop for α < 30° and α > 60°, with constant angles of 135° and - 60° with σH, respectively. Mechanical interaction between fractures in a fracture zone, quantified as change in slip compared to an isolated fracture, decreases with increasing fracture separation. Fracture underlap elongates the fracture length and therefore increases the amount of slip, while fracture overlap exhibits the opposite effect. Fracture slip decreases with an increasing amount of directly adjacent fractures. Mechanical interaction becomes negligible for fracture configurations with spacing-to-length and spacing-to-overlap ratios exceeding 0.5 and that in this case fractures are decoupled. Independent of the pre-existing fracture configuration, the development of a secondary systematic fracture set driven by a remote stress rotation is dominated by σH; development of wing cracks or shear zones is restricted to the fracture tips. Blocks with tapered geometries are present in models with a variable fracture strike, where the maximum principal stress (σ1, applying the geological convention that compressive stresses are positive) trajectories consistently deviate from σH; the presence of two systematic σ1 trajectory orientations suggests

  16. Modulation of Spinal GABAergic Inhibition and Mechanical Hypersensitivity following Chronic Compression of Dorsal Root Ganglion in the Rat

    PubMed Central

    Lee, Moon Chul; Nam, Taick Sang; Jung, Se Jung; Gwak, Young S.; Leem, Joong Woo

    2015-01-01

    Chronic compression of dorsal root ganglion (CCD) results in neuropathic pain. We investigated the role of spinal GABA in CCD-induced pain using rats with unilateral CCD. A stereological analysis revealed that the proportion of GABA-immunoreactive neurons to total neurons at L4/5 laminae I–III on the injured side decreased in the early phase of CCD (post-CCD week 1) and then returned to the sham-control level in the late phase (post-CCD week 18). In the early phase, the rats showed an increase in both mechanical sensitivity of the hind paw and spinal WDR neuronal excitability on the injured side, and such increase was suppressed by spinally applied muscimol (GABA-A agonist, 5 nmol) and baclofen (GABA-B agonist, 25 nmol), indicating the reduced spinal GABAergic inhibition involved. In the late phase, the CCD-induced increase in mechanical sensitivity and neuronal excitability returned to pre-CCD levels, and such recovered responses were enhanced by spinally applied bicuculline (GABA-A antagonist, 15 nmol) and CGP52432 (GABA-B antagonist, 15 nmol), indicating the regained spinal GABAergic inhibition involved. In conclusion, the alteration of spinal GABAergic inhibition following CCD and leading to a gradual reduction over time of CCD-induced mechanical hypersensitivity is most likely due to changes in GABA content in spinal GABA neurons. PMID:26451259

  17. Fabrication and mechanical properties of PLLA/PCL/HA composites via a biomimetic, dip coating, and hot compression procedure.

    PubMed

    Charles, L F; Shaw, M T; Olson, J R; Wei, M

    2010-06-01

    Currently, the bone-repair biomaterials market is dominated by high modulus metals and their alloys. The problem of stress-shielding, which results from elastic modulus mismatch between these metallic materials and natural bone, has stimulated increasing research into the development of polymer-ceramic composite materials that can more closely match the modulus of bone. In this study, we prepared poly(L: -lactic acid)/hydroxyapatite/poly(epsilon-caprolactone) (PLLA/HA/PCL) composites via a four-step process, which includes surface etching of the fiber, the deposition of the HA coating onto the PLLA fibers through immersion in simulated body fluid (SBF), PCL coating through a dip-coating process, and hot compression molding. The initial HA-coated PLLA fiber had a homogeneous and continuous coating with a gradient structure. The effects of HA: PCL ratio and molding temperature on flexural mechanical properties were studied and both were shown to be important to mechanical properties. Mechanical results showed that at low molding temperatures and up to an HA: PCL volume ratio of 1, the flexural strain decreased while the flexural modulus and strength increased. At higher mold temperatures with a lower viscosity of the PCL a HA: PCL ratio of 1.6 gave similar properties. The process successfully produced composites with flexural moduli near the lower range of bone. Such composites may have clinical use for load bearing bone fixation. PMID:20238147

  18. Measurement of chest wall displacement based on terahertz wave

    NASA Astrophysics Data System (ADS)

    Li, Hui; Lv, Hao; Jiao, Teng; Lu, Guohua; Li, Sheng; Li, Zhao; Liu, Miao; Jing, Xijing; Wang, Jianqi

    2015-02-01

    Measurement of chest wall displacement is an important approach for measuring mechanics of chest wall, which has considerable significance for assessing respiratory system and diagnosing pulmonary diseases. However, existing optical methods for measuring chest wall displacement are inconvenient for some specific patients such as the female patients and the patients with bandaged chest. In this letter, we proposed a method for measuring chest wall displacement based on terahertz wave and established corresponding mathematic model and set up a terahertz measurement system. The main advantages of this method are that it can measure the chest wall displacement of the subjects without taking off clothes or arranging any markers. To validate this method and assess the performance of the terahertz system, in vitro, the displacement of a water module driven by a linear guide rail was measured by the terahertz system and compared with the actual displacement of the water module. The results showed that the waveforms measured with two methods have a good agreement, and the relative error is less than 5% and sufficiently good for measurement demands. In vivo, the synchronous experiment was performed on five human volunteers with the terahertz system and a respiratory belt transducer. The results demonstrate that this method has good performance and promising prospects for measuring chest wall displacement.

  19. Male chest enhancement: pectoral implants.

    PubMed

    Benito-Ruiz, J; Raigosa, J M; Manzano-Surroca, M; Salvador, L

    2008-01-01

    The authors present their experience with the pectoral muscle implant for male chest enhancement in 21 patients. The markings and technique are thoroughly described. The implants used were manufactured and custom made. The candidates for implants comprised three groups: group 1 (18 patients seeking chest enhancement), group 2 (1 patient with muscular atrophy), and group 3 (2 patients with muscular injuries). Because of the satisfying results obtained, including significant enhancement of the chest contour and no major complications, this technique is used for an increasing number of male cosmetic surgeries. PMID:17676376

  20. Painful Chest Wall Swellings: Tietze Syndrome or Chest Wall Tumor?

    PubMed

    Kaplan, Tevfik; Gunal, Nesimi; Gulbahar, Gultekin; Kocer, Bulent; Han, Serdar; Eryazgan, Mehmet Ali; Ozsoy, Arzu; Naldoken, Seniha; Alhan, Aslıhan; Sakinci, Unal

    2016-04-01

    Background Tietze syndrome (TS) is an inflammatory condition characterized by chest pain and swelling of costochondral junction. Primary chest wall tumors may mimic TS. In this article, we report our experience of approximately 121 patients initially diagnosed as TS and determined chest wall tumor in some cases at the follow-up. Methods This is a retrospective review of patients diagnosed as TS by clinical examination, chest X-ray, electrocardiogram, routine laboratory tests, and computed tomography (CT) of chest: all treated and followed up between March 2001 and July 2012. There were 121 cases (41 males and 80 females; mean age, 39.6 ± 3.2 years) of TS. Results In 27 patients with initial normal radiological findings, the size of swellings had doubled during the follow-up period (mean, 8.51 ± 2.15 months). These patients were reevaluated with chest CT and bone scintigraphy and then early diagnostic biopsy was performed. Pathologic examination revealed primary chest wall tumor in 13 patients (5 malignant, 8 benign). CT had a sensitivity of 92.3% and a specificity of 64.2% in detection of tumors (kappa: 0.56, p = 0.002), whereas the sensitivity and the specificity of bone scan were 84.6 and 35.7%, respectively (kappa: 0.199, p = 0.385). Conclusion Primary chest wall tumors could mimic TS. Bone scintigraphy or CT is not specific enough to determine malignant and other benign disorders of costochondral junction. Therefore, clinicians should follow TS patients more closely, and in case of increasing size of swelling, early diagnostic biopsy should be considered. PMID:25742551

  1. Mechanics of Boundary Layer Transition. Part 5: Boundary Layer Stability theory in incompressible and compressible flow

    NASA Technical Reports Server (NTRS)

    Mack, L. M.

    1967-01-01

    The fundamentals of stability theory, its chief results, and the physical mechanisms at work are presented. The stability theory of the laminar boundary determines whether a small disturbance introduced into the boundary layer will amplify or damp. If the disturbance damps, the boundary layer remains laminar. If the disturbance amplifies, and by a sufficient amount, then transition to turbulence eventually takes place. The stability theory establishes those states of the boundary layer which are most likely to lead to transition, identifys those frequencies which are the most dangerous, and indicates how the external parameters can best be changed to avoid transition.

  2. Mechanisms of flow through compressible porous beds in sedimentation, centrifugation, deliquoring, and ceramic processing

    SciTech Connect

    1996-01-25

    The major topics covered in the investigation include: centrifugation; cake filtration; sedimentation and thickening; capillary suction operations; ceramics, slip casting; optimization studies; and wastewater. The research program was aimed at the specific areas of solid/liquid separation including sedimentation, thickening, cake filtration, centrifugation, expression, washing, deep-bed filtration, screening, and membrane separation. Unification of the theoretical approaches to the various solid/liquid separation operations was the principle objective of the research. Exploring new aspects of basic separation mechanisms, verification of theory with experiment, development of laboratory procedures for obtaining data for design, optimizing operational methods, and transferring the results to industry were part of the program.

  3. ENDOCHONDRAL GROWTH IN GROWTH PLATES OF THREE SPECIES AT TWO ANATOMICAL LOCATIONS MODULATED BY MECHANICAL COMPRESSION AND TENSION

    PubMed Central

    Stokes, Ian A.F.; Aronsson, David D.; Dimock, Abigail N.; Cortright, Valerie; Beck., Samantha

    2006-01-01

    SUMMARY Purpose Sustained mechanical loading alters longitudinal growth of bones, and this growth sensitivity to load has been implicated in progression of skeletal deformities during growth. The objective of this study was to quantify the relationship between altered growth and different magnitudes of sustained altered stress in a diverse set of non-human growth plates. Methods The sensitivity of endochondral growth to differing magnitudes of sustained compression or distraction stress was measured in growth plates of three species of immature animals (rats, rabbits, calves) at two anatomical locations (caudal vertebra and proximal tibia) with two different ages of rats and rabbits. An external loading apparatus was applied for eight days and growth was measured as the distance between fluorescent markers administered 24 and 48 hours prior to euthanasia. Results An apparently linear relationship between stress and percentage growth modulation (percent difference between loaded and control growth plates) was found, with distraction accelerating growth and compression slowing growth. The growth-rate sensitivity to stress was between 9.2 and 23.9% per 0.1 MPa for different growth plates, and averaged 17.1% per 0.1 MPa. The growth-rate sensitivity to stress differed between vertebrae and the proximal tibia (15 and 18.6 percent per 0.1 MPa respectively). The range of control growth rates of different growth plates was large (30 microns/day for rat vertebrae to 366 microns/day for rabbit proximal tibia). Conclusions The relatively small differences in growth-rate sensitivity to stress for a diverse set of growth plates suggests that these results might be generalized to other growth plates, including human. These data may be applicable to planning the management of progressive deformities in patients having residual growth. PMID:16705695

  4. On the mechanical behavior of WS2 nanotubes under axial tension and compression

    PubMed Central

    Kaplan-Ashiri, Ifat; Cohen, Sidney R.; Gartsman, Konstantin; Ivanovskaya, Viktoria; Heine, Thomas; Seifert, Gotthard; Wiesel, Inna; Wagner, H. Daniel; Tenne, Reshef

    2006-01-01

    The mechanical properties of materials and particularly the strength are greatly affected by the presence of defects; therefore, the theoretical strength (≈10% of the Young's modulus) is not generally achievable for macroscopic objects. On the contrary, nanotubes, which are almost defect-free, should achieve the theoretical strength that would be reflected in superior mechanical properties. In this study, both tensile tests and buckling experiments of individual WS2 nanotubes were carried out in a high-resolution scanning electron microscope. Tensile tests of MoS2 nanotubes were simulated by means of a density-functional tight-binding-based molecular dynamics scheme as well. The combination of these studies provides a microscopic picture of the nature of the fracture process, giving insight to the strength and flexibility of the WS2 nanotubes (tensile strength of ≈16 GPa). Fracture analysis with recently proposed models indicates that the strength of such nanotubes is governed by a small number of defects. A fraction of the nanotubes attained the theoretical strength indicating absence of defects. PMID:16407141

  5. Mechanisms of fracture of the free surface of shock-compressed metals

    SciTech Connect

    Mokhova, V. V. Mikhailov, A. L.; Til’kunov, A. V.; Orlov, N. I.; Kanunova, L. I.; Bragunets, V. A.; Tkachenko, M. I.; Simakov, V. G.; Sokolov, S. S.; Podurets, A. M.

    2015-12-15

    The mechanisms of the ejection of aluminum and copper microparticles from the free surfaces of these metals have been studied under conditions of the escape of a moderate-intensity shock wave from a sample. The free surfaces of samples contained 0.7–0.9 mm deep artificial wells and protrusions simulating (on a greater scale of 10: 1) the natural surface roughness retained upon mechanical processing. The pressure in a shock-wave pulse at the base of a protrusion was controlled within P = 5–20 GPa (i.e., below the melting region), and the variable duration of pressure pulses was 0.02, 0.2, and 1 μs. Analysis of the free surfaces of postloaded samples showed that, for certain loading and roughness parameters, the ejection of metal from vertices of protruding ridges or pyramids (as a result of the longitudinal fracture) was about ten times greater than the amount of metal ejected in the form of cumulative jets from wells. The amount of ejected metal and the size distribution of metal microparticles were quantitatively characterized using “soft collecting targets” and by measuring mass losses of samples upon fracture.

  6. Chest drainage systems in use.

    PubMed

    Zisis, Charalambos; Tsirgogianni, Katerina; Lazaridis, George; Lampaki, Sofia; Baka, Sofia; Mpoukovinas, Ioannis; Karavasilis, Vasilis; Kioumis, Ioannis; Pitsiou, Georgia; Katsikogiannis, Nikolaos; Tsakiridis, Kosmas; Rapti, Aggeliki; Trakada, Georgia; Karapantzos, Ilias; Karapantzou, Chrysanthi; Zissimopoulos, Athanasios; Zarogoulidis, Konstantinos; Zarogoulidis, Paul

    2015-03-01

    A chest tube is a flexible plastic tube that is inserted through the chest wall and into the pleural space or mediastinum. It is used to remove air in the case of pneumothorax or fluid such as in the case of pleural effusion, blood, chyle, or pus when empyema occurs from the intrathoracic space. It is also known as a Bülau drain or an intercostal catheter. Insertion of chest tubes is widely performed by radiologists, pulmonary physicians and thoracic surgeons. Large catheters or small catheters are used based on each situation that the medical doctor encounters. In the current review we will focus on the chest drain systems that are in use. PMID:25815304

  7. Chest drainage systems in use

    PubMed Central

    Zisis, Charalambos; Tsirgogianni, Katerina; Lazaridis, George; Lampaki, Sofia; Baka, Sofia; Mpoukovinas, Ioannis; Karavasilis, Vasilis; Kioumis, Ioannis; Pitsiou, Georgia; Katsikogiannis, Nikolaos; Tsakiridis, Kosmas; Rapti, Aggeliki; Trakada, Georgia; Karapantzos, Ilias; Karapantzou, Chrysanthi; Zissimopoulos, Athanasios; Zarogoulidis, Konstantinos

    2015-01-01

    A chest tube is a flexible plastic tube that is inserted through the chest wall and into the pleural space or mediastinum. It is used to remove air in the case of pneumothorax or fluid such as in the case of pleural effusion, blood, chyle, or pus when empyema occurs from the intrathoracic space. It is also known as a Bülau drain or an intercostal catheter. Insertion of chest tubes is widely performed by radiologists, pulmonary physicians and thoracic surgeons. Large catheters or small catheters are used based on each situation that the medical doctor encounters. In the current review we will focus on the chest drain systems that are in use. PMID:25815304

  8. Mechanisms of strong pressure wave generations during knocking combustion: compressible reactive flow simulations with detailed chemical kinetics

    NASA Astrophysics Data System (ADS)

    Terashima, Hiroshi; Koshi, Mitsuo

    2014-11-01

    Knocking is a very severe pressure oscillation caused by interactions between flame propagation and end-gas autoignition in spark-assisted engines. In this study, knocking combustion modeled in one-dimensional space is simulated using a highly efficient compressible flow solver with detailed chemical kinetics for clarifying the process of knocking occurrence. Especially, mechanisms of strong pressure wave generation are addressed. A robust and fast explicit integration method is used to efficiently handle stiff chemistry, and species bundling for effectively estimating the diffusion coefficients. The detailed mechanisms such as n-butane of 113 species and n-heptane of 373 species are directly applied. Results demonstrate that the negative temperature coefficient (NTC) region of n-heptane significantly influence the knocking timing and intensity. In the NTC region, stronger pressure wave is generated due to rapid heat release of a very small portion in the end-gas, which is attributed to low temperature oxidation and inhomogeneous temperature distributions in the end-gas. The knocking intensity is thus amplified in the NTC region, taking a maximum value. In the case of n-butane with no NTC region, relatively weak knocking intensity is observed in all conditions with no clear peak.

  9. Diametral compression test: Analysing the H/ D ratio influence on the mechanical resistance of UO 2-green pellets

    NASA Astrophysics Data System (ADS)

    Santana, H. H. S.; Maier, G.; Ródenas, J.

    2010-07-01

    Fired ceramic components and green compacted bodies from ceramic powder are both fragile structures. Their particles have weak mechanical links or are just agglomerated by a binder. Due to the compaction process failure can occur during unloading and ejection stages and also after a certain level of densification or powder cohesion has been achieved. Ceramic materials normally have worse standard deviation in the splitting tensile strength values when subjected to static or dynamic impact tests than metals. The height-to-diameter ( H/ D) ratio has been studied for several materials showing that by having different geometrical correlations the mechanical resistance of the tested specimens is highly affected. Cylindrical UO 2-green pellet samples, having approximately the same density with three different diameters and four different heights, were pressed and experimentally studied by means of the diametral compression (Brazilian) test. By combining the diameters and the heights different H/ D ratios could be tested. Results, which were analysed using Weibull statistics, showed that the cylinder size has a great influence on the Weibull module ( m), whereas for the Weibull tensile strength no conclusive tendency could be observed except if we keep the height fixed and increase the pellet diameter. Pellets having the same height showed an increased tendency for the m value if their diameter is increased. The largest volume by each diameter has the highest Weibull module values.

  10. The Impact of Posture on the Mechanical Properties of a Functional Spinal Unit During Cyclic Compressive Loading.

    PubMed

    Barrett, Jeff M; Gooyers, Chad E; Karakolis, Thomas; Callaghan, Jack P

    2016-08-01

    To assess how posture affects the transmission of mechanical energy up the spinal column during vibration, 18 porcine functional spinal units (FSUs) were exposed to a sinusoidal force (1500 ± 1200 N) at 5 Hz for 120 min in either a flexed, extended, or neutral posture. Force and FSU height were measured continuously throughout the collection. From these data, specimen height loss, dynamic stiffness, hysteresis, and parameters from a standard linear solid (SLS) model were determined and analyzed for differences between postures. Posture had an influence on all of these parameters. In extension, the FSU had higher dynamic stiffness values than when neutral or flexed (p < 0.0001). In flexion, the FSU had higher hysteresis than both an extended or neutral posture (p < 0.0001). Height loss was greatest in a flexed posture and smallest in an extended posture (p < 0.0001). In extension, the series spring element in the SLS model had a stiffness value higher than both flexed and neutral posture conditions, whereas the stiffness in the parallel spring was the same between extension and neutral (p < 0.01), both higher than in flexion. Viscosity coefficients were highest in extension compared to both flexed and neutral (p < 0.01). Based on these results, it was determined that posture had a significant influence in determining the mechanical properties of the spine when exposed to cyclic compressive loading. PMID:27322199

  11. Chest trauma: A case for single lung ventilation

    PubMed Central

    Pandharikar, Nagaraj; Sachdev, Anil; Gupta, Neeraj; Gupta, Suresh; Gupta, Dhiren

    2016-01-01

    Chest trauma is one of the important causes of mortality and morbidity in pediatric trauma patients. The complexity, magnitude, and type of lung injury make it extremely challenging to provide optimal oxygenation and ventilation while protecting the lung from further injury due to mechanical ventilation. Independent lung ventilation is used sporadically in these patients who do not respond to these conventional ventilatory strategies using double-lumen endotracheal tubes, bronchial blocker balloons, etc. However, this equipment may not be easily available in developing countries, especially for pediatric patients. Here, we present a case of severe chest trauma with pulmonary contusion, flail chest, and bronchopleural fistula, who did not respond to conventional lung protective strategies. She was successfully managed with bronchoscopy-guided unilateral placement of conventional endotracheal tube followed by single lung ventilation leading to resolution of a chest injury. PMID:27303142

  12. Mechanisms of flow through compressible porous beds in sedimentation, filtration, centrifugation, deliquoring, and ceramic processing

    SciTech Connect

    Tiller, F.M.

    1992-06-01

    The University of Houston research program is aimed at the specific area of solid/liquid separation including sedimentation, thickening, cake filtration, centrifugation, expression, washing, deep-bed filtration, screening, and membrane separation. Unification of the theoretical approaches to the various solid/liquid separation operations is the principle objective of the research. Exploring new aspects of basic separation mechanisms, verification of theory with experiment, development of laboratory procedures for obtaining data for design, optimizing operational methods, and transferring the results to industry are a part of the Houston program. New methodology developed in our program now permits an engineer or scientist to handle thickening, cake filtration, centrigual filtration, and expression in a unified manner. The same fundamental equations are simply adapted to the differing parameters and conditions related to the various modes of separation. As the system is flexible and adaptable to computational software, new developments can continually be added. Discussions of the various research projects in this report have been kept to a minimum and are principally qualitative. The length of the report would be excessive if each topic were covered in depth. Although the number of research topics may appear larger than one would expect, many are closely interconnected and reflect our philosophy of working in apparently diverse fields such as ceramics, mining, wastewater, food, chemical processing, and oil well operations.

  13. Buckling and mechanical instability of ZnO nanorods grown on different substrates under uniaxial compression.

    PubMed

    Riaz, M; Fulati, A; Zhao, Q X; Nur, O; Willander, M; Klason, P

    2008-10-15

    Mechanical instability and buckling characterization of vertically aligned single-crystal ZnO nanorods grown on different substrates including Si, SiC and sapphire (α-Al(2)O(3)) was done quantitatively by the nanoindentation technique. The nanorods were grown on these substrates by the vapor-liquid-solid (VLS) method. The critical load for the ZnO nanorods grown on the Si, SiC and Al(2)O(3) substrates was found to be 188, 205 and 130 µN, respectively. These observed critical loads were for nanorods with 280 nm diameters and 900 nm length using Si as a substrate, while the corresponding values were 330 nm, 3300 nm, and 780 nm, 3000 nm in the case of SiC and Al(2)O(3) substrates, respectively. The corresponding buckling energies calculated from the force displacement curves were 8.46 × 10(-12), 1.158 × 10(-11) and 1.092 × 10(-11) J, respectively. Based on the Euler model for long nanorods and the J B Johnson model (which is an extension of the Euler model) for intermediate nanorods, the modulus of elasticity of a single rod was calculated for each sample. Finally, the critical buckling stress and strain were also calculated for all samples. We found that the buckling characteristic is strongly dependent on the quality, lattice mismatch and adhesion of the nanorods with the substrate. PMID:21832659

  14. Postoperative Complications Leading to Death after Coagulum Pyelolithotomy in a Tetraplegic Patient: Can We Prevent Prolonged Ileus, Recurrent Intestinal Obstruction due to Adhesions Requiring Laparotomies, Chest Infection Warranting Tracheostomy, and Mechanical Ventilation?

    PubMed Central

    Vaidyanathan, Subramanian; Soni, Bakul; Singh, Gurpreet; Hughes, Peter

    2013-01-01

    A 22-year-old male sustained C-6 tetraplegia in 1992. In 1993, intravenous pyelography revealed normal kidneys. Suprapubic cystostomy was performed. He underwent open cystolithotomy in 2004 and 2008. In 2009, computed tomography revealed bilateral renal calculi. Coagulum pyelolithotomy of left kidney was performed. Pleura and peritoneum were opened. Peritoneum could not be closed. Following surgery, he developed pulmonary atelectasis; he required tracheostomy and mechanical ventilation. He did not tolerate nasogastric feeding. CT of abdomen revealed bilateral renal calculi and features of proximal small bowel obstruction. Laparotomy revealed small bowel obstruction due to dense inflammatory adhesions involving multiple small bowel loops which protruded through the defect in sigmoid mesocolon and fixed posteriorly over the area of previous intervention. All adhesions were divided. The wide defect in mesocolon was not closed. In 2010, this patient again developed vomiting and distension of abdomen. Laparotomy revealed multiple adhesions. He developed chest infection and required ventilatory support again. He developed pressure sores and depression. Later abdominal symptoms recurred. This patient's general condition deteriorated and he expired in 2011. Conclusion. Risk of postoperative complications could have been reduced if minimally invasive surgery had been performed instead of open surgery to remove stones from left kidney. Suprapubic cystostomy predisposed to repeated occurrence of stones in urinary bladder and kidneys. Spinal cord physicians should try to establish intermittent catheterisation regime in tetraplegic patients. PMID:23533931

  15. [Chest ultrasonography in pleurapulmonary disease].

    PubMed

    Gallego Gómez, M P; García Benedito, P; Pereira Boo, D; Sánchez Pérez, M

    2014-01-01

    Although the initial diagnosis and follow-up of pleuropulmonary disease are normally done with plain chest films and the gold standard for chest disease is computed tomography, diverse studies have established the usefulness of chest ultrasonography in the diagnosis of different pleuropulmonary diseases like pleural effusion and lung consolidation, among others. In this article, we show the different ultrasonographic patterns for pleuropulmonary disease. The availability of ultrasonography in different areas (ICU, recovery areas) makes this technique especially important for critical patients because it obviates the need to transfer the patient. Moreover, ultrasonography is noninvasive and easy to repeat. On the other hand, it enables the direct visualization of pleuropulmonary disease that is necessary for interventional procedures. PMID:22819690

  16. A Rat Model of Ventricular Fibrillation and Resuscitation by Conventional Closed-chest Technique.

    PubMed

    Lamoureux, Lorissa; Radhakrishnan, Jeejabai; Gazmuri, Raúl J

    2015-01-01

    A rat model of electrically-induced ventricular fibrillation followed by cardiac resuscitation using a closed chest technique that incorporates the basic components of cardiopulmonary resuscitation in humans is herein described. The model was developed in 1988 and has been used in approximately 70 peer-reviewed publications examining a myriad of resuscitation aspects including its physiology and pathophysiology, determinants of resuscitability, pharmacologic interventions, and even the effects of cell therapies. The model featured in this presentation includes: (1) vascular catheterization to measure aortic and right atrial pressures, to measure cardiac output by thermodilution, and to electrically induce ventricular fibrillation; and (2) tracheal intubation for positive pressure ventilation with oxygen enriched gas and assessment of the end-tidal CO2. A typical sequence of intervention entails: (1) electrical induction of ventricular fibrillation, (2) chest compression using a mechanical piston device concomitantly with positive pressure ventilation delivering oxygen-enriched gas, (3) electrical shocks to terminate ventricular fibrillation and reestablish cardiac activity, (4) assessment of post-resuscitation hemodynamic and metabolic function, and (5) assessment of survival and recovery of organ function. A robust inventory of measurements is available that includes - but is not limited to - hemodynamic, metabolic, and tissue measurements. The model has been highly effective in developing new resuscitation concepts and examining novel therapeutic interventions before their testing in larger and translationally more relevant animal models of cardiac arrest and resuscitation. PMID:25938619

  17. [Imaging signs in chest diagnostics].

    PubMed

    Krombach, G A

    2016-08-01

    Signs in chest imaging are defined as typical findings which can be easily recognized on x‑ray photographs or computed tomography (CT) scans of the chest. They are caused by different typical pathophysiological processes. Due to the association of a certain pathophysiological cause with a given sign, knowledge and use of these signs can allow the possible differential diagnoses to be narrowed down. If other imaging findings and clinical data are additionally taken into account, the diagnosis can be made with a high degree of confidence in many cases. PMID:27369549

  18. Chest pain syndromes in pregnancy.

    PubMed

    Sahni, Gagan

    2012-08-01

    Chest pain syndromes in pregnancy include numerous catastrophic cardiovascular events. Acute myocardial infarction, aortic dissection, pulmonary embolism, and amniotic fluid embolism are the most important causes of nonobstetric mortality and morbidity in pregnancy. Each of these could result in poor maternal and fetal outcomes if not diagnosed and treated in a timely fashion. However, their diagnosis and management is limited by fetal risks of diagnostic procedures, dangers of pharmacotherapy and interventions that have neither been widely studied nor validated. This article reviews the current literature on epidemiology, risk factors, pathogenesis, diagnosis, and management of 4 potentially lethal chest pain syndromes in pregnancy. PMID:22813362

  19. Contemporary management of flail chest.

    PubMed

    Vana, P Geoff; Neubauer, Daniel C; Luchette, Fred A

    2014-06-01

    Thoracic injury is currently the second leading cause of trauma-related death and rib fractures are the most common of these injuries. Flail chest, as defined by fracture of three or more ribs in two or more places, continues to be a clinically challenging problem. The underlying pulmonary contusion with subsequent inflammatory reaction and right-to-left shunting leading to hypoxia continues to result in high mortality for these patients. Surgical stabilization of the fractured ribs remains controversial. We review the history of management for flail chest alone and when combined with pulmonary contusion. Finally, we propose an algorithm for nonoperative and surgical management. PMID:24887787

  20. Mechanical Testing of PMCs under Simulated Rapid Heat-Up Propulsion Environments. II; In-Plane Compressive Behavior

    NASA Technical Reports Server (NTRS)

    Stokes, Eric H.; Shin, E. Eugene; Sutter, James K.

    2003-01-01

    .e., plastization of polymeric material by water, the internal pressure generated by the volatilization of water at elevated temperatures, and hydrolytic chemical decomposition. However, moisture is lost from the material at increasing rates as temperature increases. Second, because PMCs are good thermal insulators, when they are externally heated at even mild rates large thermal gradients can develop within the material. At temperatures where a material property changes rapidly with temperature the presence of a large thermal gradient is unacceptable for intrinsic property characterization purposes. Therefore, long hold times are required to establish isothermal conditions. However, in the service environments high-heating-rates, high temperatures, high-loading rates are simultaneous present along with residual moisture. In order to capture the effects of moisture on the material, holding at- temperature until isothermal conditions are reached is unacceptable particularly in materials with small physical dimensions. Thus, the effects due to moisture on the composite's mechanical characteristics, ie., their so-called analog response, may be instructive. One approach employed in this program was rapid heat-up (approx. 200 F/sec.) and loading of both dry and wet in-plane compressive specimens to examine the effects of moisture on this resin dominated mechanical property of the material.

  1. Control of shock unsteadiness in shock boundary-layer interaction on a compression corner using mechanical vortex generators

    NASA Astrophysics Data System (ADS)

    Verma, S. B.; Manisankar, C.; Raju, C.

    2012-07-01

    An experimental study was conducted to control the unsteadiness of separation shock in a Mach 2 24° compression ramp-induced interaction using mechanical vortex generators (VG). Control devices in the form of an array of single-row delta-ramps were placed upstream of the interaction region and tested for two streamwise locations with respect to the boundary layer thickness ( δ) at the interaction location and height ` h' of the delta-ramps, i.e., at 27.5 δ or h/ δ = 0.65 and at 12.5 δ or h/ δ = 0.26, respectively. Surface oil study revealed traces of streamwise counter-rotating vortex pairs generated downstream of these devices. Measurements using pressure-sensitive paint also showed a spanwise sinusoidal pattern of wall pressure variation indicating generation of streamwise vortices from these control devices. These vortices, on interaction with the reverse flow in the separation bubble, replaced a well-defined separation line (for no control) by a highly corrugated separation line. In the region of separation, the mean pressure distribution gets modified while the peak rms value in the intermittent region of separation showed significant changes. Additionally, the spanwise spacing ` s' of the vertex of the delta ramps seemed to be an important parameter in controlling the peak rms value. A decrease in this spacing, i.e., VG1 with s = 0, significantly reduced the peak rms value (by 50 and 35 %) while an increase in the spacing, i.e., VG2 with s = 1 mm, consistently showed an increase (by 12 and 30 %) in the separation shock unsteadiness relative to no control, irrespective of their placement location (of h/ δ = 0.65 and 0.26, respectively).

  2. Acute Myocardial Infarction Following Blunt Chest Trauma and Coronary Artery Dissection.

    PubMed

    Abdolrahimi, Safar Ali; Sanati, Hamid Reza; Ansari-Ramandi, Mohammad Mostafa; Heris, Saeed Oni; Maadani, Mohsen

    2016-06-01

    Blunt chest traumatic coronary artery dissection is an uncommon cause of atherosclerotic and non-atherosclerotic Acute Myocardial Infarction (AMI). Injuries of the coronary artery after blunt chest trauma are caused by different mechanisms such as vascular spasm, dissection and intimal tear or rupture of an existing thrombus formation. Chest pain might be masked by other injuries in patients with multiple traumas in car accident. Present case report is on a 37-year-old male without any specific past medical history who reported to the emergency department of a hospital with chest discomfort and was discharged with the impression of chest wall pain. After three days he experienced severe chest pain and he was admitted with the impression of acute coronary syndrome and underwent coronary angiography which showed Left Anterior Descending (LAD) artery dissection. The possibility of injury of the coronary artery should be kept in mind after blunt trauma to the chest. This condition is sometimes underdiagnosed. Its diagnosis may be difficult because chest pain can be interpreted as being secondary to chest wall contusion or it may be overshadowed by other injuries. Coronary dissection diagnosis after chest trauma requires clinical suspicion and systematic evaluation. Electrocardiography (ECG) should be done for every patient with thoracic trauma as the clinical findings may be misleading. PMID:27504338

  3. Acute Myocardial Infarction Following Blunt Chest Trauma and Coronary Artery Dissection

    PubMed Central

    Abdolrahimi, Safar Ali; Sanati, Hamid Reza; Ansari-Ramandi, Mohammad Mostafa; Heris, Saeed Oni

    2016-01-01

    Blunt chest traumatic coronary artery dissection is an uncommon cause of atherosclerotic and non-atherosclerotic Acute Myocardial Infarction (AMI). Injuries of the coronary artery after blunt chest trauma are caused by different mechanisms such as vascular spasm, dissection and intimal tear or rupture of an existing thrombus formation. Chest pain might be masked by other injuries in patients with multiple traumas in car accident. Present case report is on a 37-year-old male without any specific past medical history who reported to the emergency department of a hospital with chest discomfort and was discharged with the impression of chest wall pain. After three days he experienced severe chest pain and he was admitted with the impression of acute coronary syndrome and underwent coronary angiography which showed Left Anterior Descending (LAD) artery dissection. The possibility of injury of the coronary artery should be kept in mind after blunt trauma to the chest. This condition is sometimes underdiagnosed. Its diagnosis may be difficult because chest pain can be interpreted as being secondary to chest wall contusion or it may be overshadowed by other injuries. Coronary dissection diagnosis after chest trauma requires clinical suspicion and systematic evaluation. Electrocardiography (ECG) should be done for every patient with thoracic trauma as the clinical findings may be misleading. PMID:27504338

  4. Compression asphyxia from a human pyramid.

    PubMed

    Tumram, Nilesh Keshav; Ambade, Vipul Namdeorao; Biyabani, Naushad

    2015-12-01

    In compression asphyxia, respiration is stopped by external forces on the body. It is usually due to an external force compressing the trunk such as a heavy weight on the chest or abdomen and is associated with internal injuries. In present case, the victim was trapped and crushed under the falling persons from a human pyramid formation for a "Dahi Handi" festival. There was neither any severe blunt force injury nor any significant pathological natural disease contributing to the cause of death. The victim was unable to remove himself from the situation because his cognitive responses and coordination were impaired due to alcohol intake. The victim died from asphyxia due to compression of his chest and abdomen. Compression asphyxia resulting from the collapse of a human pyramid and the dynamics of its impact force in these circumstances is very rare and is not reported previously to the best of our knowledge. PMID:26059277

  5. Chest tomosynthesis: technical and clinical perspectives.

    PubMed

    Johnsson, Ase Allansdotter; Vikgren, Jenny; Bath, Magnus

    2014-02-01

    The recent implementation of chest tomosynthesis is built on the availability of large, dose-efficient, high-resolution flat panel detectors, which enable the acquisition of the necessary number of projection radiographs to allow reconstruction of section images of the chest within one breath hold. A chest tomosynthesis examination obtains the increased diagnostic information provided by volumetric imaging at a radiation dose comparable to that of conventional chest radiography. There is evidence that the sensitivity of chest tomosynthesis may be at least three times higher than for conventional chest radiography for detection of pulmonary nodules. The sensitivity increases with increasing nodule size and attenuation and decreases for nodules with subpleural location. Differentiation between pleural and subpleural lesions is a known pitfall due to the limited depth resolution in chest tomosynthesis. Studies on different types of pathology report increased detectability in favor of chest tomosynthesis in comparison to chest radiography. The technique provides improved diagnostic accuracy and confidence in the diagnosis of suspected pulmonary lesions on chest radiography and facilitates the exclusion of pulmonary lesions in a majority of patients, avoiding the need for computed tomography (CT). However, motion artifacts can be a cumbersome limitation and breathing during the tomosynthesis image acquisition may result in severe artifacts significantly affecting the detectability of pathology. In summary, chest tomosynthesis has been shown to be superior to chest conventional radiography for many tasks and to be able to replace CT in selected cases. In our experience chest tomosynthesis is an efficient problem solver in daily clinical work. PMID:24481756

  6. Crush injuries of the chest

    PubMed Central

    Davidson, I. A.; Bargh, W.; Cruickshank, A. N.; Duthie, W. H.

    1969-01-01

    Fifty-four patients previously treated for a severe chest injury in an artificial ventilation unit have been followed up. An attempt has been made to determine their state of health and activity. Particular attention has been paid to their respiratory function. The significance of the findings has been discussed. Images PMID:4899979

  7. Chest physiotherapy in acute bronchiolitis.

    PubMed Central

    Webb, M S; Martin, J A; Cartlidge, P H; Ng, Y K; Wright, N A

    1985-01-01

    Forty four children with acute bronchiolitis were given twice daily chest physiotherapy in addition to standard supportive measures and were compared with 46 controls who were not given physiotherapy. There was no clinically discernable benefit on the course of their illness. PMID:3907510

  8. 30 CFR 56.6133 - Powder chests.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd., Room 2436, Arlington, Virginia 22209... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Powder chests. 56.6133 Section 56.6133 Mineral... chests. (a) Powder chests (day boxes) shall be— (1) Structurally sound, weather-resistant, equipped...

  9. 30 CFR 57.6133 - Powder chests.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Powder chests. 57.6133 Section 57.6133 Mineral... § 57.6133 Powder chests. (a) Powder chests (day boxes) shall be— (1) Structurally sound,...

  10. 30 CFR 57.6133 - Powder chests.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Powder chests. 57.6133 Section 57.6133 Mineral... § 57.6133 Powder chests. (a) Powder chests (day boxes) shall be— (1) Structurally sound,...

  11. 30 CFR 56.6133 - Powder chests.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd., Room 2436, Arlington, Virginia 22209... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Powder chests. 56.6133 Section 56.6133 Mineral... chests. (a) Powder chests (day boxes) shall be— (1) Structurally sound, weather-resistant, equipped...

  12. 30 CFR 57.6133 - Powder chests.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Powder chests. 57.6133 Section 57.6133 Mineral... § 57.6133 Powder chests. (a) Powder chests (day boxes) shall be— (1) Structurally sound,...

  13. 30 CFR 56.6133 - Powder chests.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd., Room 2436, Arlington, Virginia 22209... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Powder chests. 56.6133 Section 56.6133 Mineral... chests. (a) Powder chests (day boxes) shall be— (1) Structurally sound, weather-resistant, equipped...

  14. Chest pain in sickle cell disease.

    PubMed

    Tonino, S H; Nur, E; Otten, H M; Wykrzykowska, J J; Hoekstra, J B L; Biemond, B J

    2013-06-01

    The differential diagnosis of chest pain in a patient with sickle cell disease is difficult and may encompass several serious conditions, including chest syndrome, pulmonary embolism and infectious complications. In this manuscript we provide an overview on the various underlying diseases that may cause chest pain in patients with sickle cell disease and provide clues for a proper diagnostic workup. PMID:23799317

  15. 30 CFR 57.6133 - Powder chests.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Powder chests. 57.6133 Section 57.6133 Mineral... § 57.6133 Powder chests. (a) Powder chests (day boxes) shall be— (1) Structurally sound,...

  16. 30 CFR 57.6133 - Powder chests.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Powder chests. 57.6133 Section 57.6133 Mineral... § 57.6133 Powder chests. (a) Powder chests (day boxes) shall be— (1) Structurally sound,...

  17. Micromechanical finite-element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone-hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering.

    PubMed

    Eshraghi, Shaun; Das, Suman

    2012-08-01

    Bioresorbable scaffolds with mechanical properties suitable for bone tissue engineering were fabricated from polycaprolactone (PCL) and hydroxyapatite (HA) by selective laser sintering (SLS) and modeled by finite-element analysis (FEA). Both solid gage parts and scaffolds having 1-D, 2-D and 3-D orthogonal, periodic porous architectures were made with 0, 10, 20 and 30 vol.% HA. PCL:HA scaffolds manufactured by SLS had nearly full density (99%) in the designed solid regions and had excellent geometric and dimensional control. Through optimization of the SLS process, the compressive moduli for our solid gage parts and scaffolds are the highest reported in the literature for additive manufacturing. The compressive moduli of solid gage parts were 299.3, 311.2, 415.5 and 498.3 MPa for PCL:HA loading at 100:0, 90:10, 80:20 and 70:30, respectively. The compressive effective stiffness tended to increase as the loading of HA was increased and the designed porosity was lowered. In the case of the most 3-D porous scaffold, the compressive modulus more than doubled from 14.9 to 36.2 MPa when changing the material from 100:0 to 70:30 PCL:HA. A micromechanical FEA model was developed to investigate the reinforcement effect of HA loading on the compressive modulus of the bulk material. Using a first-principles based approach, the random distribution of HA particles in a solidified PCL matrix was modeled for any HA loading to predict the bulk mechanical properties of the composites. The bulk mechanical properties were also used for FEA of the scaffold geometries. The results of the FEA were found to be in good agreement with experimental mechanical testing. The development of patient- and site-specific composite tissue-engineering constructs with tailored properties can be seen as a direct extension of this work on computational design, a priori modeling of mechanical properties and direct digital manufacturing. PMID:22522129

  18. Micromechanical finite element modeling and experimental characterization of the compressive mechanical properties of polycaprolactone:hydroxyapatite composite scaffolds prepared by selective laser sintering for bone tissue engineering

    PubMed Central

    Eshraghi, Shaun; Das, Suman

    2012-01-01

    Bioresorbable scaffolds with mechanical properties suitable for bone tissue engineering were fabricated from polycaprolactone (PCL) and hydroxyapatite (HA) by selective laser sintering (SLS) and modeled by finite element analysis (FEA). Both solid gage parts and scaffolds having 1-D, 2-D and 3-D orthogonal, periodic porous architectures were made with 0, 10, 20 and 30% HA by volume. PCL:HA scaffolds manufactured by SLS had nearly full density (99%) in the designed solid regions and had excellent geometric and dimensional control. Through optimization of the SLS process, the compressive moduli for our solid gage parts and scaffolds are the highest reported in the literature for additive manufacturing. The compressive moduli of solid gage parts were 299.3, 311.2, 415.5 and 498.3 MPa for PCL:HA loading at 100:0, 90:10, 80:20 and 70:30 respectively. The compressive effective stiffness tended to increase as the loading of HA was increased and the designed porosity was lowered. In the case of the most 3-D porous scaffold, the compressive modulus more than doubled from 14.9 MPa to 36.2 MPa when changing the material from 100:0 to 70:30 PCL:HA. A micromechanical finite element analysis (FEA) model was developed to investigate the reinforcement effect of HA loading on the compressive modulus of the bulk material. Using a first-principles based approach, the random distribution of HA particles in a solidified PCL matrix was modeled for any loading of HA to predict the bulk mechanical properties of the composites. The bulk mechanical properties were also used for FEA of the scaffold geometries. Results of the FEA were found to be in good agreement with experimental mechanical testing. The development of patient and site-specific composite tissue engineering constructs with tailored properties can be seen as a direct extension of this work on computational design, a priori modeling of mechanical properties and direct digital manufacturing. PMID:22522129

  19. Using a magnetized plasma jet colliding with a heavy gas cloud to investigate MIF adiabatic heating and compression mechanisms

    NASA Astrophysics Data System (ADS)

    Bellan, Paul; Wongwaitayakornkul, Pakorn; Chai, Kil-Byoung; Greig, Amelia; Li, Hui

    2015-11-01

    Magnetized inertial fusion (MIF) is based on having an imploding liner adiabatically compress a magnetized plasma to the density and temperature required for thermonuclear fusion. The goal of the Caltech research program is to determine the scaling of the temperature and density increase when an actual experimental plasma is adiabatically compressed. The plasma parameters will be more modest than a fusion-grade configuration, but in compensation, the shot repetition rate will be much higher and the experiments will be non-destructive. The non-destructive feature results from having a high-speed magnetized plasma jet impact a localized heavy gas. From the point of view of an observer in the frame of the magnetized plasma jet, it will look as if the heavy gas is impacting and compressing the magnetized plasma and so, except for some geometrical differences, the configuration is equivalent to a liner impacting and compressing a stationary magnetized plasma. The experiment will be modeled by 3D numerical MHD and PIC codes. (as of approximately September 15).

  20. Computed tomography of the chest

    SciTech Connect

    Godwin, J.D.

    1984-01-01

    In this reference book readers have access to information pertaining to the role of thoracic CT, its limitations, normal anatomy and variations, scanning techniques, confusing artifacts, and pathologic anatomy. Major sections provide detailed, explicit data on lung cancer staging, the thoracic inlet, the heart, the esophagus, CT-guided invasive techniques, and the pediatric chest CT. Controversies are explored fully and presented fairly. This book is profusely illustrated with almost 500 CT scans for greater recognition and comprehension of the material presented.

  1. Radiology of occupational chest disease

    SciTech Connect

    Solomon, A. ); Kreel, L.

    1989-01-01

    Radiologic manifestations of occupational lung disease are summarized and classified in this book according to the ILO system. The interpretation of chest roentgenograms outlines the progression of each disease and is accompanied with clinically-oriented explanations. Some of the specific diseases covered include asbestosis, coal worker's pneumoconiosis, silicosis, non-mining inhalation of silica and silicates, beryllium induced disease, inhalation of organics and metallics, and occupationally induced asthma.

  2. Compression embedding

    DOEpatents

    Sandford, II, Maxwell T.; Handel, Theodore G.; Bradley, Jonathan N.

    1998-01-01

    A method and apparatus for embedding auxiliary information into the digital representation of host data created by a lossy compression technique and a method and apparatus for constructing auxiliary data from the correspondence between values in a digital key-pair table with integer index values existing in a representation of host data created by a lossy compression technique. The methods apply to data compressed with algorithms based on series expansion, quantization to a finite number of symbols, and entropy coding. Lossy compression methods represent the original data as ordered sequences of blocks containing integer indices having redundancy and uncertainty of value by one unit, allowing indices which are adjacent in value to be manipulated to encode auxiliary data. Also included is a method to improve the efficiency of lossy compression algorithms by embedding white noise into the integer indices. Lossy compression methods use loss-less compression to reduce to the final size the intermediate representation as indices. The efficiency of the loss-less compression, known also as entropy coding compression, is increased by manipulating the indices at the intermediate stage. Manipulation of the intermediate representation improves lossy compression performance by 1 to 10%.

  3. Compression embedding

    DOEpatents

    Sandford, M.T. II; Handel, T.G.; Bradley, J.N.

    1998-07-07

    A method and apparatus for embedding auxiliary information into the digital representation of host data created by a lossy compression technique and a method and apparatus for constructing auxiliary data from the correspondence between values in a digital key-pair table with integer index values existing in a representation of host data created by a lossy compression technique are disclosed. The methods apply to data compressed with algorithms based on series expansion, quantization to a finite number of symbols, and entropy coding. Lossy compression methods represent the original data as ordered sequences of blocks containing integer indices having redundancy and uncertainty of value by one unit, allowing indices which are adjacent in value to be manipulated to encode auxiliary data. Also included is a method to improve the efficiency of lossy compression algorithms by embedding white noise into the integer indices. Lossy compression methods use loss-less compression to reduce to the final size the intermediate representation as indices. The efficiency of the loss-less compression, known also as entropy coding compression, is increased by manipulating the indices at the intermediate stage. Manipulation of the intermediate representation improves lossy compression performance by 1 to 10%. 21 figs.

  4. Compression embedding

    DOEpatents

    Sandford, II, Maxwell T.; Handel, Theodore G.; Bradley, Jonathan N.

    1998-01-01

    A method of embedding auxiliary information into the digital representation of host data created by a lossy compression technique. The method applies to data compressed with lossy algorithms based on series expansion, quantization to a finite number of symbols, and entropy coding. Lossy compression methods represent the original data as integer indices having redundancy and uncertainty in value by one unit. Indices which are adjacent in value are manipulated to encode auxiliary data. By a substantially reverse process, the embedded auxiliary data can be retrieved easily by an authorized user. Lossy compression methods use loss-less compressions known also as entropy coding, to reduce to the final size the intermediate representation as indices. The efficiency of the compression entropy coding, known also as entropy coding is increased by manipulating the indices at the intermediate stage in the manner taught by the method.

  5. Compression embedding

    DOEpatents

    Sandford, M.T. II; Handel, T.G.; Bradley, J.N.

    1998-03-10

    A method of embedding auxiliary information into the digital representation of host data created by a lossy compression technique is disclosed. The method applies to data compressed with lossy algorithms based on series expansion, quantization to a finite number of symbols, and entropy coding. Lossy compression methods represent the original data as integer indices having redundancy and uncertainty in value by one unit. Indices which are adjacent in value are manipulated to encode auxiliary data. By a substantially reverse process, the embedded auxiliary data can be retrieved easily by an authorized user. Lossy compression methods use loss-less compressions known also as entropy coding, to reduce to the final size the intermediate representation as indices. The efficiency of the compression entropy coding, known also as entropy coding is increased by manipulating the indices at the intermediate stage in the manner taught by the method. 11 figs.

  6. Ba-Filling Effect on the Uniaxial Tensile and Compressive Mechanical Behavior of Crystalline CoSb3: A Molecular Dynamics Study

    NASA Astrophysics Data System (ADS)

    Yang, Xu-qiu; Li, Wen-juan; Chen, Gang; Zhai, Peng-cheng

    2015-06-01

    Filled skutterudites, which possess application potential, are believed to be a class of novel thermoelectric materials. The contribution of atomic filling to the significant decrease of phonon conductivity is investigated extensively in the literature. However, the filling effect on the fundamental mechanical behavior is not so far very clear. In the present study, molecular dynamics simulations have been performed to investigate the effect of Ba-filling on the uniaxial tensile and compressive mechanical properties of crystalline CoSb3 with a multibody interatomic potential. First, we constructed the fully Ba-filled CoSb3 model according to the ideal lattice structure. For comparison, pure binary CoSb3 was also modeled. Then, the simulation models were relaxed to reach more favorable configurations. Thereafter, the uniaxial tension and compression were carried out by strain-controlling until failure at room temperature. Stress-strain curves were obtained during the whole deformation process. The atomic rearrangements and failure patterns were also examined. The comparison of these mechanical responses between the filled and unfilled CoSb3 was made and analyzed. The results are expected to be helpful for the application of high-performance skutterudites.

  7. Chest wall resection for extrapulmonary tumor.

    PubMed

    Long, W P; Kline, R; Levine, E A

    1997-09-01

    Despite progress in early detection of breast cancer, a minority of women continue to present with extensive disease which may necessitate chest wall resection. Between 1992 and 1996, 14 patients were treated by surgical resection of the chest wall and reconstruction by the LSU Sections of Surgical Oncology and Plastic Surgery. Indications included resection of primary tumor, resection of recurrent tumor, and resection of radiation therapy induced damage to the chest wall. We report chest wall excision and reconstruction with no operative mortality and minor surgical morbidity in 21% of cases. Local control was achieved in 13 of 14 cases. Additionally we report uniform success in the palliation of ulcerating, painful, or infected chest wall lesions. Approximately 25% of patients treated for breast cancer and followed up for more than 6 months have remained free of disease. Chest wall resection is a useful modality in selected patients with extensive disease. PMID:9316348

  8. Compressive Holography

    NASA Astrophysics Data System (ADS)

    Lim, Se Hoon

    Compressive holography estimates images from incomplete data by using sparsity priors. Compressive holography combines digital holography and compressive sensing. Digital holography consists of computational image estimation from data captured by an electronic focal plane array. Compressive sensing enables accurate data reconstruction by prior knowledge on desired signal. Computational and optical co-design optimally supports compressive holography in the joint computational and optical domain. This dissertation explores two examples of compressive holography: estimation of 3D tomographic images from 2D data and estimation of images from under sampled apertures. Compressive holography achieves single shot holographic tomography using decompressive inference. In general, 3D image reconstruction suffers from underdetermined measurements with a 2D detector. Specifically, single shot holographic tomography shows the uniqueness problem in the axial direction because the inversion is ill-posed. Compressive sensing alleviates the ill-posed problem by enforcing some sparsity constraints. Holographic tomography is applied for video-rate microscopic imaging and diffuse object imaging. In diffuse object imaging, sparsity priors are not valid in coherent image basis due to speckle. So incoherent image estimation is designed to hold the sparsity in incoherent image basis by support of multiple speckle realizations. High pixel count holography achieves high resolution and wide field-of-view imaging. Coherent aperture synthesis can be one method to increase the aperture size of a detector. Scanning-based synthetic aperture confronts a multivariable global optimization problem due to time-space measurement errors. A hierarchical estimation strategy divides the global problem into multiple local problems with support of computational and optical co-design. Compressive sparse aperture holography can be another method. Compressive sparse sampling collects most of significant field

  9. Hydatid disease of the chest

    PubMed Central

    Xanthakis, D.; Efthimiadis, M.; Papadakis, G.; Primikirios, N.; Chassapakis, G.; Roussaki, A.; Veranis, N.; Akrivakis, A.; Aligizakis, C. J.

    1972-01-01

    Ninety-one cases of hydatid disease of the chest are reported. Eighty-eight were involving the lung, two the chest wall, and one the mediastinum. All the patients were treated surgically. Conservative operations (simple removal of the parasite and closure of the remaining cavity) were performed in 78 patients, 37 unruptured and 41 ruptured cysts. Late postoperative complications occurred in eleven. In 10 patients, recurrent haemoptysis was the main symptom due to residual cavity in four, bronchiectatic changes in two, and unknown aetiology in four. In one patient, recurrence of multiple cysts occurred in the affected lobe. Radical operations were carried out in 10 patients, including segmental resection in four and lobectomy in six. Conservative operations were performed in all cases of unruptured cysts, with the exception of a giant cyst in which resection was the operation of choice. For ruptured cysts with mild infection conservative operation was also performed. Resection was necessary only in patients with ruptured cysts with suppuration, bronchiectatic changes, and giant cysts replacing a whole lobe. There was no mortality. We believe that conservative operation is the treatment of choice for hydatid disease of the lung. Indications for resection are very limited. Images

  10. Common errors in evaluating chest radiographs.

    PubMed

    Mann, H

    1990-01-01

    Chest radiographs that are correctly obtained and interpreted provide valuable diagnostic information. However, some radiographs are not taken at total lung capacity, and the appearance of the lungs on film may mimic certain lung disorders. Most common interpretive pitfalls in chest radiography can be avoided by physicians who are familiar with the film appearance of varying degrees of lung inflation, technical limitations of portable radiography, and common chest abnormalities. When further definition is necessary, additional projections should be obtained. Chest fluoroscopy and computed tomography can offer further clarification, if needed. PMID:2296566

  11. Compressive mechanical compatibility of anisotropic porous Ti6Al4V alloys in the range of physiological strain rate for cortical bone implant applications.

    PubMed

    Li, Fuping; Li, Jinshan; Kou, Hongchao; Huang, Tingting; Zhou, Lian

    2015-09-01

    Porous titanium and its alloys are believed to be promising materials for bone implant applications, since they can reduce the "stress shielding" effect by tailoring porosity and improve fixation of implant through bone ingrowth. In the present work, porous Ti6Al4V alloys for biomedical application were fabricated by diffusion bonding of alloy meshes. Compressive mechanical behavior and compatibility in the range of physiological strain rate were studied under quasi-static and dynamic conditions. The results show that porous Ti6Al4V alloys possess anisotropic structure with elongated pores in the out-of-plane direction. For porous Ti6Al4V alloys with 60-70 % porosity, more than 40 % pores are in the range of 200-500 μm which is the optimum pore size suited for bone ingrowth. Quasi-static Young's modulus and yield stress of porous Ti6Al4V alloys with 30-70 % relative density are in the range of 6-40 GPa and 100-500 MPa, respectively. Quasi-static compressive properties can be quantitatively tailored by porosity to match those of cortical bone. Strain rate sensitivity of porous Ti6Al4V alloys is related to porosity. Porous Ti6Al4V alloys with porosity higher than 50 % show enhanced strain rate sensitivity, which is originated from that of base materials and micro-inertia effect. Porous Ti6Al4V alloys with 60-70 % porosity show superior compressive mechanical compatibility in the range of physiological strain rate for cortical bone implant applications. PMID:26384823

  12. An Analytical Solution for Mechanical Responses Induced by Temperature and Air Pressure in a Lined Rock Cavern for Underground Compressed Air Energy Storage

    NASA Astrophysics Data System (ADS)

    Zhou, Shu-Wei; Xia, Cai-Chu; Du, Shi-Gui; Zhang, Ping-Yang; Zhou, Yu

    2015-03-01

    Mechanical responses induced by temperature and air pressure significantly affect the stability and durability of underground compressed air energy storage (CAES) in a lined rock cavern. An analytical solution for evaluating such responses is, thus, proposed in this paper. The lined cavern of interest consists of three layers, namely, a sealing layer, a concrete lining and the host rock. Governing equations for cavern temperature and air pressure, which involve heat transfer between the air and surrounding layers, are established first. Then, Laplace transform and superposition principle are applied to obtain the temperature around the lined cavern and the air pressure during the operational period. Afterwards, a thermo-elastic axisymmetrical model is used to analytically determine the stress and displacement variations induced by temperature and air pressure. The developments of temperature, displacement and stress during a typical operational cycle are discussed on the basis of the proposed approach. The approach is subsequently verified with a coupled compressed air and thermo-mechanical numerical simulation and by a previous study on temperature. Finally, the influence of temperature on total stress and displacement and the impact of the heat transfer coefficient are discussed. This paper shows that the temperature sharply fluctuates only on the sealing layer and the concrete lining. The resulting tensile hoop stresses on the sealing layer and concrete lining are considerably large in comparison with the initial air pressure. Moreover, temperature has a non-negligible effect on the lined cavern for underground compressed air storage. Meanwhile, temperature has a greater effect on hoop and longitudinal stress than on radial stress and displacement. In addition, the heat transfer coefficient affects the cavern stress to a higher degree than the displacement.

  13. Atypical Chest Pain: An Unusual Presentation of Spinal Metastasis due to Penile Carcinoma

    PubMed Central

    Pywell, Sarah; Dott, Cameron; Khan, Mohammad Taimur; Sivanadarajah, Naveethan

    2016-01-01

    Spinal metastases may present in a myriad of ways, most commonly back pain with or without neurology. We report an unusual presentation of isolated atypical chest pain preceding metastatic cord compression, secondary to penile carcinoma. Spinal metastasis from penile carcinoma is rare with few cases reported. This unusual presentation highlights the need for a heightened level of clinical suspicion for spinal metastases as a possible cause for chest pain in any patients with a history of carcinoma. The case is discussed with reference to the literature. PMID:27429829

  14. The modified cam clay model for constrained compression of human morsellised bone: effects of porosity on the mechanical behaviour.

    PubMed

    Lunde, Knut B; Skallerud, Bjørn

    2009-01-01

    Morsellised cortico-cancellous bone (MCB) is often used in revision surgery for filling skeletal defects. The MCB porosity is found to influence the degree of bone ingrowth. Thus expressing a material model in terms of porosity may be attractive from a clinical point of view. We analysed the moisture content and performed constrained compression testing of human impacted and unimpacted MCB, in order to determine material parameters for the common constitutive soil model: modified cam clay. The model seemed to be suitable for the unimpacted pellets with a logarithmic bulk modulus kappa=0.059+/-0.0019 and a logarithmic hardening constant lambda=0.36+/-0.014. This model, relating the specific volume (and porosity) to the logarithm of stress, may be suited to find the best compromise of stiffness and porosity for MCB. PMID:19627806

  15. Compression asphyxia in upright suspended position.

    PubMed

    Tumram, Nilesh Keshav; Ambade, Vipul Namdeorao; Dixit, Pradeep Gangadhar

    2014-06-01

    In compression asphyxia, the respiration is prevented by external pressure on the body. It is usually due to external force compressing the trunk due to heavy weight over chest/abdomen and is associated with internal injuries. In the present case, the victim was suspended in an upright position owing to wedging of the chest and the abdomen in the gap between 2 parallel bridges undergoing construction. There was neither any heavy weight over the body, nor was any external force applied over the trunk. Moreover, there was neither any severe blunt force injury nor any significant pathological natural disease contributing to the cause of death. The body was wedged in the gap between 2 static hard surfaces. The victim was unable to extricate himself from the position owing to impairment of cognitive responses and coordination due to influence of alcohol. The victim died as a result of "static" asphyxia due to compression of the chest and the abdomen. Compression asphyxia in upright suspended position under this circumstance is very rare and not reported previously to the best of our knowledge. PMID:24781404

  16. Evaluation of damage progression and mechanical behavior under compression of bone cements containing core-shell nanoparticles by using acoustic emission technique.

    PubMed

    Pacheco-Salazar, O F; Wakayama, Shuichi; Sakai, Takenobu; Cauich-Rodríguez, J V; Ríos-Soberanis, C R; Cervantes-Uc, J M

    2015-06-01

    In this work, the effect of the incorporation of core-shell particles on the fracture mechanisms of the acrylic bone cements by using acoustic emission (AE) technique during the quasi-static compression mechanical test was investigated. Core-shell particles were composed of a poly(butyl acrylate) (PBA) rubbery core and a methyl methacrylate/styrene copolymer (P(MMA-co-St)) outer glassy shell. Nanoparticles were prepared with different core-shell ratio (20/80, 30/70, 40/60 and 50/50) and were incorporated into the solid phase of bone cement at several percentages (5, 10 and 15 wt%). It was observed that the particles exhibited a spherical morphology averaging ca. 125 nm in diameter, and the dynamic mechanical analysis (DMA) thermograms revealed the desired structuring pattern of phases associated with core-shell structures. A fracture mechanism was proposed taking into account the detected AE signals and the scanning electron microscopy (SEM) micrographs. In this regard, core-shell nanoparticles can act as both additional nucleation sites for microcracks (and crazes) and to hinder the microcrack propagation acting as a barrier to its growth; this behavior was presented by all formulations. Cement samples containing 15 wt% of core-shell nanoparticles, either 40/60 or 50/50, were fractured at 40% deformation. This fact seems related to the coalescence of microcracks after they surround the agglomerates of core-shell nanoparticles to continue growing up. This work also demonstrated the potential of the AE technique to be used as an accurate and reliable detection tool for quasi-static compression test in acrylic bone cements. PMID:25792411

  17. Left Main Ostial Compression in a Patient with Pulmonary Hypertension: Dynamic Findings by IVUS

    PubMed Central

    Seabra, Luciana F.; Ribeiro, Henrique B.; de Barros e Silva, Pedro Gabriel Melo; Rodrigues, Marcelo J.; Spadaro, André G.; Conejo, Fábio; Godinho, Roger R.; Faig, Sandro M. M.; de Macedo, Thiago Andrade; de P. S. Baptista, Luciana; de Resende, Marcos Valerio C.; Furlan, Valter; Ribeiro, Expedito E.

    2015-01-01

    Patient: Female, 39 Final Diagnosis: Idiopathic pulmonary arterial hypertension Symptoms: Chest pain Medication: — Clinical Procedure: Percutaneous coronary intervention Specialty: Cardiology and Pulmonology Objective: Rare co-existance of disease or pathology Background: Pulmonary artery dilatation is a common feature among patients with severe pulmonary hypertension. Left main coronary artery extrinsic compression by an enlarged pulmonary artery is a rare complication and a potential cause for chest pain and sudden cardiac death in patients with pulmonary hypertension. This situation is very rare and few reports have described it. Currently, the appropriate management of these patients remains unknown. Case Report: In the present report we describe the case of a 39-year-old woman who presented with a 2-year history of cardiac symptoms related to exercise. The patient underwent a 64-slice multidetector computed tomography (MDCT) coronary angiography, which showed left main coronary artery (LMCA) compression by a markedly enlarged pulmonary artery trunk (44 mm), without intraluminal stenosis or coronary artery calcium, as determined by the Agatston score. This compression was considered to be the cause of the cardiac symptoms. To confirm and plan the treatment, the patient underwent cardiac catheterization that confirmed the diagnosis of pulmonary hypertension and LMCA critical obstruction. Taking into account the paucity of information regarding the best management in these cases, the treatment decision was shared among a “heart team” that chose percutaneous coronary intervention with stent placement. An intra-vascular ultrasound was performed during the procedure, which showed a dynamic compression of the left main coronary artery. The intervention was successfully executed without any adverse events. Conclusions: This case illustrates dynamic compression of the LMCA by IVUS, visually demonstrating the mechanism of the intermittent symptoms of myocardial

  18. Hitherto unknown shear rupture mechanism as a source of instability in intact hard rocks at highly confined compression

    NASA Astrophysics Data System (ADS)

    Tarasov, Boris G.

    2014-05-01

    Today, frictional shear resistance along pre-existing faults is considered to be the lower limit on rock shear strength for confined conditions corresponding to the seismogenic layer. This paper introduces a recently identified shear rupture mechanism providing a paradoxical feature of hard rocks - the possibility of shear rupture propagation through the highly confined intact rock mass at shear stress levels significantly less than frictional strength. In the new mechanism, the rock failure associated with consecutive creation of small slabs (known as ‘domino-blocks') from the intact rock in the rupture tip is driven by a fan-shaped domino structure representing the rupture head. The fan-head combines such unique features as: extremely low shear resistance, self-sustaining stress intensification, and self-unbalancing conditions. Due to this the failure process caused by the mechanism is very dynamic and violent. This makes it impossible to directly observe and study the mechanism and can explain why the mechanism has not been detected before. This paper provides physical motivation for the mechanism, based upon side effects accompanying the failure process. Physical and mathematical models of the mechanism presented in the paper explain unique and paradoxical features of the mechanism. The new shear rupture mechanism allows a novel point of view for understanding the nature of spontaneous failure processes in hard rocks including earthquakes.

  19. Bronchial cancer - chest x-ray (image)

    MedlinePlus

    This is a chest x-ray of a person with bronchial cancer. This is a front view. The lungs are the two dark ... white areas visible in the middle of the chest. The light areas that appear as subtle branches ...

  20. [Wooden chests for the midwife's equipment].

    PubMed

    Carlén-Nilsson, C

    1993-01-01

    In the museum of medical history in Lund there are several wooden chests containing partly identical instruments apparently belonging to a midwife. The instruments dated from before 1900, e.g. lancets and horn cups for blood-letting, a pewter enema syringe, a wooden stethoscope, a "tobacco pipe" and glass bottles. The use of the tobacco pipe was first puzzling, but it appeared to be a breast reliver. What do we know about the date of the chests? One chest has belonged to Kjersti Nilsdotter, a midwife educated in Lund 1872-1873. Her certificate was in the chest. From Ronnie Hunt, Minnesota we have got information about another chest of the same type. That belonged to Nelly Gustafsson, a midwife educated in Lund probably about 1870. She emigrated to USA and was a practising midwife in Lindstrom, Minnesota from about 1900. PMID:11639439

  1. Intercostal hemangioma of the chest wall

    PubMed Central

    Hamzík, Julian

    2016-01-01

    The authors describe a case of a 36-year-old patient who had six months’ pain of the thoracic spine and left chest. A soft slowly growing resistance was present on the dorso-lateral side of the left chest wall, in the range of the seventh to ninth rib. According to the medical history, the patient did not have any prior trauma and malignancy. A well-defined tumor of the left chest wall with calcifications, which grew to the seventh and eighth intercostal space, was present on computed tomography (CT) and magnetic resonance (MR) scans. The patient underwent resection of the tumor with the chest wall and reconstruction with polypropylene mesh. Histologically, it was a venous hemangioma, one of very rare tumors of the chest wall. PMID:27212983

  2. [How to do - the chest tube drainage].

    PubMed

    Klopp, Michael; Hoffmann, Hans; Dienemann, Hendrik

    2015-03-01

    A chest tube is used to drain the contents of the pleural space to reconstitute the physiologic pressures within the pleural space and to allow the lungs to fully expand. Indications for chest tube placement include pneumothorax, hemothorax, pleural effusion, pleural empyema, and major thoracic surgery. The most appropriate site for chest tube placement is the 4th or 5th intercostal space in the mid- or anterior- axillary line. Attention to technique in placing the chest tube is vital to avoid complications from the procedure. Applying the step-by-step technique presented, placement of a chest tube is a quick and safe procedure. Complications - frequently occurring when the tube is inserted with a steel trocar - include hemothorax, dislocation, lung lacerations, and injury to organs in the thoracic or abdominal cavity." PMID:25734676

  3. Structural and Mechanical Improvements to Bone Are Strain Dependent with Axial Compression of the Tibia in Female C57BL/6 Mice

    PubMed Central

    Berman, Alycia G.; Clauser, Creasy A.; Wunderlin, Caitlin; Hammond, Max A.; Wallace, Joseph M.

    2015-01-01

    Strain-induced adaption of bone has been well-studied in an axial loading model of the mouse tibia. However, most outcomes of these studies are restricted to changes in bone architecture and do not explore the mechanical implications of those changes. Herein, we studied both the mechanical and morphological adaptions of bone to three strain levels using a targeted tibial loading mouse model. We hypothesized that loading would increase bone architecture and improve cortical mechanical properties in a dose-dependent fashion. The right tibiae of female C57BL/6 mice (8 week old) were compressively loaded for 2 weeks to a maximum compressive force of 8.8N, 10.6N, or 12.4N (generating periosteal strains on the anteromedial region of the mid-diaphysis of 1700 με, 2050 με, or 2400 με as determined by a strain calibration), while the left limb served as an non-loaded control. Following loading, ex vivo analyses of bone architecture and cortical mechanical integrity were assessed by micro-computed tomography and 4-point bending. Results indicated that loading improved bone architecture in a dose-dependent manner and improved mechanical outcomes at 2050 με. Loading to 2050 με resulted in a strong and compelling formation response in both cortical and cancellous regions. In addition, both structural and tissue level strength and energy dissipation were positively impacted in the diaphysis. Loading to the highest strain level also resulted in rapid and robust formation of bone in both cortical and cancellous regions. However, these improvements came at the cost of a woven bone response in half of the animals. Loading to the lowest strain level had little effect on bone architecture and failed to impact structural- or tissue-level mechanical properties. Potential systemic effects were identified for trabecular bone volume fraction, and in the pre-yield region of the force-displacement and stress-strain curves. Future studies will focus on a moderate load level which

  4. Compressible halftoning

    NASA Astrophysics Data System (ADS)

    Anderson, Peter G.; Liu, Changmeng

    2003-01-01

    We present a technique for converting continuous gray-scale images to halftone (black and white) images that lend themselves to lossless data compression with compression factor of three or better. Our method involves using novel halftone mask structures which consist of non-repeated threshold values. We have versions of both dispersed-dot and clustered-dot masks, which produce acceptable images for a variety of printers. Using the masks as a sort key allows us to reversibly rearrange the image pixels and partition them into groups with a highly skewed distribution allowing Huffman compression coding techniques to be applied. This gives compression ratios in the range 3:1 to 10:1.

  5. Painful palpitations: chest pain associated with postextrasystolic ST depression.

    PubMed

    Ul Haq, Ehtesham; Kleyn, Emile; Omar, Bassam

    2014-01-01

    Postextrasystolic T-wave changes have been described as early as 1915. The significance and mechanism of such changes remain controversial. Because postextrasystolic ST changes are rare, much of the ensuing discussion concentrates on the closely related and more commonly reported phenomenon of postextrasystolic T-wave inversion. This report documents the case of a 67-year-old man with a history of coronary artery disease who was admitted to the hospital with chest pain. PMID:25662929

  6. Impact of acid and alkaline pretreatments on the molecular network of wheat gluten and on the mechanical properties of compression-molded glassy wheat gluten bioplastics.

    PubMed

    Jansens, Koen J A; Lagrain, Bert; Brijs, Kristof; Goderis, Bart; Smet, Mario; Delcour, Jan A

    2013-10-01

    Wheat gluten can be converted into rigid biobased materials by high-temperature compression molding at low moisture contents. During molding, a cross-linked protein network is formed. This study investigated the effect of mixing gluten with acid/alkali in 70% ethanol at ambient temperature for 16 h followed by ethanol removal, freeze-drying, and compression molding at 130 and 150 °C on network formation and on types of cross-links formed. Alkaline pretreatment (0-100 mmol/L sodium hydroxide or 25 mmol/L potassium hydroxide) strongly affected gluten cross-linking, whereas acid pretreatment (0-25 mmol/L sulfuric acid or 25 mmol/L hydrochloric acid) had limited effect on the gluten network. Molded alkaline-treated gluten showed enhanced cross-linking but also degradation when treated with high alkali concentrations, whereas acid treatment reduced gluten cross-linking. β-Elimination of cystine and lanthionine formation occurred more pronouncedly at higher alkali concentrations. In contrast, formation of disulfide and nondisulfide cross-links during molding was hindered in acid-pretreated gluten. Bioplastic strength was higher for alkali than for acid-pretreated samples, whereas the flexural modulus was only slightly affected by either alkaline or acid pretreatment. Apparently, the ratio of disulfide to nondisulfide cross-links did not affect the mechanical properties of rigid gluten materials. PMID:24016229

  7. Grain size dependence of dynamic mechanical behavior of AZ31B magnesium alloy sheet under compressive shock loading

    SciTech Connect

    Asgari, H.; Odeshi, A.G.; Szpunar, J.A.; Zeng, L.J.; Olsson, E.

    2015-08-15

    The effects of grain size on the dynamic deformation behavior of rolled AZ31B alloy at high strain rates were investigated. Rolled AZ31B alloy samples with grain sizes of 6, 18 and 37 μm, were subjected to shock loading tests using Split Hopkinson Pressure Bar at room temperature and at a strain rate of 1100 s{sup −} {sup 1}. It was found that a double-peak basal texture formed in the shock loaded samples. The strength and ductility of the alloy under the high strain-rate compressive loading increased with decreasing grain size. However, twinning fraction and strain hardening rate were found to decrease with decreasing grain size. In addition, orientation imaging microscopy showed a higher contribution of double and contraction twins in the deformation process of the coarse-grained samples. Using transmission electron microscopy, pyramidal dislocations were detected in the shock loaded sample, proving the activation of pyramidal slip system under dynamic impact loading. - Highlights: • A double-peak basal texture developed in all shock loaded samples. • Both strength and ductility increased with decreasing grain size. • Twinning fraction and strain hardening rate decreased with decreasing grain size. • ‘g.b’ analysis confirmed the presence of dislocations in shock loaded alloy.

  8. Mechanical behaviors and failure processes of precracked specimens under uniaxial compression: A perspective from microscopic displacement patterns

    NASA Astrophysics Data System (ADS)

    Liu, Ting; Lin, Baiquan; Zou, Quanle; Zhu, Chuanjie; Yan, Fazhi

    2016-03-01

    Hydraulic slotting is an efficient permeability enhancement method that has been widely used in China for enhanced coalbed methane (ECBM) recovery. Although some research has been conducted on hydraulic slotting, the mechanical behaviors such as strength, deformation, and cracking processes of coal treated by this technique are still unclear. This paper numerically investigates the mechanical behaviors of specimens containing combined flaws with various inclination angles. Research results show that different flaw inclination angles result in variations in strength and deformation of precracked specimens. We also analyzed the crack initiation, propagation, and coalescence processes to understand the underlying mechanisms for the aforementioned variations. To evaluate the crack initiation and propagation process and its corresponding mechanisms, we proposed 12 types of displacement field modes from the perspective of particles relative motion. Based on this, evolution of the displacement field during loading process is analyzed and 11 types of crack and three types of crack initiation modes are extracted from the cracking processes of specimens with different inclination angles. Analysis of the displacement field not only indicates the type of each crack, but also reveals the formation mechanism of the three crack initiation modes. A comparison between the numerical results and the previous laboratory test results shows that numerical simulation can reproduce most of the phenomenon observed in the laboratory test. The research result is expected to contribute to the further understanding of the mechanical behavior of coal subjected to hydraulic slotting or the stability of rock structures.

  9. Alternative Compression Garments

    NASA Technical Reports Server (NTRS)

    Stenger, M. B.; Lee, S. M. C.; Ribeiro, L. C.; Brown, A. K.; Westby, C. M.; Platts, S. H.

    2011-01-01

    Orthostatic intolerance after spaceflight is still an issue for astronauts as no in-flight countermeasure has been 100% effective. Future anti-gravity suits (AGS) may be similar to the Shuttle era inflatable AGS or may be a mechanical compression device like the Russian Kentavr. We have evaluated the above garments as well as elastic, gradient compression garments of varying magnitude and determined that breast-high elastic compression garments may be a suitable replacement to the current AGS. This new garment should be more comfortable than the AGS, easy to don and doff, and as effective a countermeasure to orthostatic intolerance. Furthermore, these new compression garments could be worn for several days after space flight as necessary if symptoms persisted. We conducted two studies to evaluate elastic, gradient compression garments. The purpose of these studies was to evaluate the comfort and efficacy of an alternative compression garment (ACG) immediately after actual space flight and 6 degree head-down tilt bed rest as a model of space flight, and to determine if they would impact recovery if worn for up to three days after bed rest.

  10. Effects of compaction pressure and particle shape on the porosity and compression mechanical properties of sintered Ti6Al4V powder compacts for hard tissue implantation.

    PubMed

    Güden, Mustafa; Celik, Emrah; Hizal, Alpay; Altindiş, Mustafa; Cetiner, Sinan

    2008-05-01

    Sintered Ti6Al4V powder compacts potentially to be used in implant applications were prepared using commercially available spherical and angular powders (100-200 mum) within the porosity range of 34-54%. Cylindrical green powder compacts were cold compacted at various pressures and then sintered at 1200 degrees C for 2 h. The final percent porosity and mean pore sizes were determined as functions of the applied compaction pressure and powder type. The mechanical properties were investigated through compression testing. Results have shown that yield strength of the powder compacts of 40-42% porosity was comparable with that of human cortical bone. As compared with previously investigated Ti powder compacts, Ti6Al4V powder compacts showed higher strength at similar porosity range. Microscopic observations on the failed compact samples revealed that failure occurred primarily by the separation of interparticle bond regions in the planes 45 degrees to the loading axis. PMID:18076095

  11. Investigation of the dosimetry of chest tomosynthesis

    NASA Astrophysics Data System (ADS)

    Svalkvist, Angelica; Zachrisson, Sara; Månsson, Lars Gunnar; Båth, Magnus

    2009-02-01

    Chest tomosynthesis has recently been introduced to healthcare as a low-dose alternative to CT or as a tool for improved diagnostics in chest radiography with only a modest increase in radiation dose to the patient. However, no detailed description of the dosimetry for this type of examination has been presented. The aim of this work was therefore to investigate the dosimetry of chest tomosynthesis. The chest tomosynthesis examination was assumed to be performed using a stationary detector and a vertically moving x-ray tube, exposing the patient from different angles. The Monte Carlo based computer software PCXMC was used to determine the effective dose delivered to a standard-sized patient from various angles using different assumptions of the distribution of the effective dose over the different projections. The obtained conversion factors between input dose measures and effective dose for chest tomosynthesis for different angular intervals were then compared with the horizontal projection. The results indicate that the error introduced by using conversion factors for the PA projection in chest radiography for estimating the effective dose of chest tomosynthesis is small for normally sized patients, especially if a conversion factor between KAP and effective dose is used.

  12. [A rare case of chest pain].

    PubMed

    Bodócsi, Beáta; Koncz, István; Hum, Zsigmond; Serfőző, Orsolya; Pap-Szekeres, József; Szabó, István

    2016-09-01

    Chest pain is a common symptom in patients who visit Emergency Departments. The main task is to exclude life-threatening diseases such as acute coronary syndrome, pulmonary embolization and dissection of thoracic aorta. The authors present the history of a patient, who had an intense chest pain for 7 hours. In accordance with the diagnostic algorithm of chest pain, ECG, blood collection, chest X-ray and chest computed tomography angiography were performed. Acute coronary syndrome, pulmonary embolization and dissection of the thoracic aorta were excluded, however, chest computed tomography CT revealed a huge hiatal hernia as an incidental finding. An emergency surgical repair was performed and the patient recovered without any complications. The authors emphasize that the diagnostic algorithms focus on the confirmation or rejection of possible life threatening diseases in case of chest pain. However, it should be kept in mind that rarer causes may occur, which may require involvement of the relevant disciplines and multidisciplinary thinking. Orv. Hetil., 2016, 157(36), 1445-1448. PMID:27596512

  13. Acute clinical benefits of chest wall-stretching exercise on expired tidal volume, dyspnea and chest expansion in a patient with chronic obstructive pulmonary disease: a single case study.

    PubMed

    Leelarungrayub, Donrawee; Pothongsunun, Prapas; Yankai, Araya; Pratanaphon, Sainatee

    2009-10-01

    Chest physical therapy (CPT) has an important role in a medical team to assist in resolving the critical problems deriving from chronic lung disease. These critical problems include increased secretion volume, difficult breathing or dyspnea, ineffective coughing, inability to be weaned off a ventilator, and physical deterioration resulting from low aerobic capacity and endurance after prolonged bed rest. The inability to be weaned off a ventilator does not only result from secretion production or muscle weakness, but other conditions including chest stiffness or immobility. The procedure to increase chest mobility includes specific chest stretching and mobilization. Chest wall-stretching exercises were composed of thoracic rotation and anterior compression with stretching in sitting position, trunk extension and rib torsion in supine lying, and lateral stretching in side lying. These exercises were given to the patient as a regular daily program along with postural drainage, percussion, breathing exercise and limb exercises. The expired tidal volume, dyspnea level, and chest expansion were evaluated and clinical efficiency was analyzed during CPT, compared to Pre-CPT and Post-CPT with Bloom table. The results showed a significant clinical improvement of expired tidal volume, reduction in dyspnea level, and increase in chest expansion. PMID:19761957

  14. Mechanical Loading of Cartilage Explants with Compression and Sliding Motion Modulates Gene Expression of Lubricin and Catabolic Enzymes

    PubMed Central

    Marková, Michala; Torzilli, Peter A.; Gallo, Luigi M.

    2015-01-01

    Objective Translation of the contact zone in articulating joints is an important component of joint kinematics, yet rarely investigated in a biological context. This study was designed to investigate how sliding contact areas affect cartilage mechanobiology. We hypothesized that higher sliding speeds would lead to increased extracellular matrix mechanical stress and the expression of catabolic genes. Design A cylindrical Teflon indenter was used to apply 50 or 100 N normal forces at 10, 40, or 70 mm/s sliding speed. Mechanical parameters were correlated with gene expressions using a multiple linear regression model. Results In both loading groups there was no significant effect of sliding speed on any of the mechanical parameters (strain, stress, modulus, tangential force). However, an increase in vertical force (from 50 to 100 N) led to a significant increase in extracellular matrix strain and stress. For 100 N, significant correlations between gene expression and mechanical parameters were found for TIMP-3 (r2 = 0.89), ADAMTS-5 (r2 = 0.73), and lubricin (r2 = 0.73). Conclusions The sliding speeds applied do not have an effect on the mechanical response of the cartilage, this could be explained by a partial attainment of the “elastic limit” at and above a sliding speed of 10 mm/s. Nevertheless, we still found a relationship between sliding speed and gene expression when the tissue was loaded with 100 N normal force. Thus despite the absence of speed-dependent mechanical changes (strain, stress, modulus, tangential force), the sliding speed had an influence on gene expression. PMID:26175864

  15. Technique for chest radiography for pneumoconiosis

    SciTech Connect

    Sargent, E.N.

    1982-01-01

    Routine radiographic chest examinations have been performed using a variety of techniques. Although chest radiography is one of the most commonly performed radiographic examinations, it is often difficult to obtain consistently good quality roentgenograms. This publication provides a simple guide and relatively easy solution to the many problems that radiologic technologists might encounter. The language is purposely relatively simple and care has been taken to avoid difficult mathematical and physical explanations. The intent is to provide an easily referrable text for those who may encounter difficulties in producing acceptable chest radiographs.

  16. Experimental Glaucoma Causes Optic Nerve Head Neural Rim Tissue Compression: A Potentially Important Mechanism of Axon Injury

    PubMed Central

    Fortune, Brad; Reynaud, Juan; Hardin, Christy; Wang, Lin; Sigal, Ian A.; Burgoyne, Claude F.

    2016-01-01

    Purpose We tested the hypothesis that experimental glaucoma (EG) results in greater thinning of the optic nerve head (ONH) neural rim tissue than the peripapillary retinal nerve fiber layer (RNFL) tissue. Methods Longitudinal spectral-domain optical coherence tomography (SDOCT) imaging of the ONH and peripapillary RNFL was performed every other week under manometric IOP control (10 mm Hg) in 51 nonhuman primates (NHP) during baseline and after induction of unilateral EG. The ONH parameter minimum rim area (MRA) was derived from 80 radial B-scans centered on the ONH; RNFL cross-sectional area (RNFLA) from a peripapillary circular B-scan with 12° diameter. Results In control eyes, MRA was 1.00 ± 0.19 mm2 at baseline and 1.00 ± 0.19 mm2 at the final session (P = 0.77), while RNFLA was 0.95 ± 0.09 and 0.95 ± 0.10 mm2, respectively (P = 0.96). In EG eyes, MRA decreased from 1.00 ± 0.19 mm2 at baseline to 0.63 ± 0.21 mm2 at the final session (P < 0.0001), while RNFLA decreased from 0.95 ± 0.09 to 0.74 ± 0.19 mm2, respectively (P < 0.0001). Thus, MRA decreased by 36.4 ± 20.6% in EG eyes, significantly more than the decrease in RNFLA (21.7 ± 19.4%, P < 0.0001). Other significant changes in EG eyes included increased Bruch's membrane opening (BMO) nonplanarity (P < 0.05), decreased BMO aspect ratio (P < 0.0001), and decreased MRA angle (P < 0.001). Bruch's membrane opening area did not change from baseline in either control or EG eyes (P = 0.27, P = 0.15, respectively). Conclusions Optic nerve head neural rim tissue thinning exceeded peripapillary RNFL thinning in NHP EG. These results support the hypothesis that axon bundles are compressed transversely within the ONH rim along with glaucomatous deformation of connective tissues. PMID:27564522

  17. Supporting the early use of echocardiography in blunt chest trauma

    PubMed Central

    2012-01-01

    This case reports a very unusual mechanism of cardiac rupture following an episode of multiple blunt chest trauma. The patient, a professional jockey, was trampled by horses, and although shocked on hospital admission, he did not present with signs and symptoms that were consistent with cardiogenic shock. This case highlights the difficult and subjective nature of clinical examination in emergency situations when dealing with cases of acute cardiac tamponade. It further emphasises the lack of sensitivity of traditional trauma imaging and investigative approaches such as the standard anteroposterior chest X-ray and electrocardiogram. The diagnosis of acute cardiac tamponade was not made until tertiary-care-centre arrival, when ultrasound technology in the form of bedside echocardiography was used, facilitating emergency surgery to repair a ruptured left ventricle. It is hoped that the sharing of this case will alert fellow clinicians to this uncommon but possible mechanism of cardiac rupture and subsequent tamponade, encourage the early use of echocardiography at the bedside in hypotensive blunt chest trauma cases and reinforce the principles of the Advanced Trauma Life Support course in treating trauma victims. PMID:22870886

  18. Biomechanics of chiasmal compression: Sensitivity of the mechanical behaviors of nerve fibers to variations in material property and geometry

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofei; Neely, Andrew J.; McIlwaine, Gawn G.; Lueck, Christian J.

    2016-05-01

    The mechanism of bitemporal hemianopia is still unclear. Previous research suggested that the nerve fiber packing pattern may contribute to the selective damage of nasal (crossed) nerve fibers. Numerical models were built using finite element modeling to study the biomechanics of optic nerve fibers. The sensitivity of the mechanical behaviors of the nerve fibers to variations of five parameters in the nerve fiber model were investigated using design of experiments (DOE). Results show that the crossing angle is a very significant factor that affects a wide range of responses of the model. The strain difference between the crossed and the uncrossed nerve fibers may account for the phenomenon of bitemporal hemianopia. This work also highlights the need for more accurate material properties of the tissues in the model and an improved understanding of the microstructure of the optic chiasm.

  19. Mechanical properties of carboniferous rocks in the Upper Silesian Coal Basin under uniaxial and triaxial compression tests

    SciTech Connect

    Bukowska, M.

    2005-04-01

    Many years' studies of geological properties of rocks from the Upper Silesian Coal Basin have resulted in acquisition of a substantial data base of mechanical parameters of rocks over the total strain range. It is found that the post-peak rock properties are closely related with the peak strength and the pre-peak properties. The relationship between the uniaxial ultimate strength, elastic modulus, and drop modulus are determined.

  20. Development of an accurate molecular mechanics model for buckling behavior of multi-walled carbon nanotubes under axial compression.

    PubMed

    Safaei, B; Naseradinmousavi, P; Rahmani, A

    2016-04-01

    In the present paper, an analytical solution based on a molecular mechanics model is developed to evaluate the elastic critical axial buckling strain of chiral multi-walled carbon nanotubes (MWCNTs). To this end, the total potential energy of the system is calculated with the consideration of the both bond stretching and bond angular variations. Density functional theory (DFT) in the form of generalized gradient approximation (GGA) is implemented to evaluate force constants used in the molecular mechanics model. After that, based on the principle of molecular mechanics, explicit expressions are proposed to obtain elastic surface Young's modulus and Poisson's ratio of the single-walled carbon nanotubes corresponding to different types of chirality. Selected numerical results are presented to indicate the influence of the type of chirality, tube diameter, and number of tube walls in detailed. An excellent agreement is found between the present numerical results and those found in the literature which confirms the validity as well as the accuracy of the present closed-form solution. It is found that the value of critical axial buckling strain exhibit significant dependency on the type of chirality and number of tube walls. PMID:26930445

  1. Video Compression

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Optivision developed two PC-compatible boards and associated software under a Goddard Space Flight Center Small Business Innovation Research grant for NASA applications in areas such as telerobotics, telesciences and spaceborne experimentation. From this technology, the company used its own funds to develop commercial products, the OPTIVideo MPEG Encoder and Decoder, which are used for realtime video compression and decompression. They are used in commercial applications including interactive video databases and video transmission. The encoder converts video source material to a compressed digital form that can be stored or transmitted, and the decoder decompresses bit streams to provide high quality playback.

  2. Aspergillosis - chest x-ray (image)

    MedlinePlus

    ... usually occurs in immunocompromised individuals. Here, a chest x-ray shows that the fungus has invaded the lung ... are usually seen as black areas on an x-ray. The cloudiness on the left side of this ...

  3. Tuberculosis, advanced - chest x-rays (image)

    MedlinePlus

    ... tissue, and can cause tissue death. These chest x-rays show advanced pulmonary tuberculosis. There are multiple light ... location of cavities within these light areas. The x-ray on the left clearly shows that the opacities ...

  4. Imaging of diseases of the chest

    SciTech Connect

    Armstrong, P.; Dee, P.; Wilson, A.

    1988-01-01

    This book promises to be the first intermediate length chest imaging book that successfully integrates material on the newer modalities (MRI, Nuclear Medicine) with that on conventional techniques (plain film radiography).

  5. Chest pain in focal musculoskeletal disorders.

    PubMed

    Stochkendahl, Mette Jensen; Christensen, Henrik Wulff

    2010-03-01

    The musculoskeletal system is a recognized source of chest pain. However, despite the apparently benign origin, patients with musculoskeletal chest pain remain under-diagnosed, untreated, and potentially continuously disabled in terms of anxiety, depression, and activities of daily living. Several overlapping conditions and syndromes of focal disorders, including Tietze syndrome, costochondritis, chest wall syndrome, muscle tenderness, slipping rib, cervical angina, and segmental dysfunction of the cervical and thoracic spine, have been reported to cause pain. For most of these syndromes, evidence arises mainly from case stories and empiric knowledge. For segmental dysfunction, clinical features of musculoskeletal chest pain have been characterized in a few clinical trials. This article summarizes the most commonly encountered syndromes of focal musculoskeletal disorders in clinical practice. PMID:20380955

  6. [Dedifferentiated Chondrosarcoma of the Chest Wall].

    PubMed

    Saitoh, Genkichi; Yoneshima, Yasuto; Nakamura, Toshihiko; Kitagawa, Dai; Kinjo, Nao; Ohgaki, Kippei; Maehara, Shinichiro; Teramoto, Seiichi; Adachi, Eisuke; Ikeda, Yoichi; Mine, Mari

    2016-08-01

    A 79-year-old man complaining of an anterior chest mass with pain had an abnormal shadow on chest X-ray. A mass, 7 cm in size, with destruction of the right 4th rib was found on chest computed tomography. A F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) corresponding to the lesion showed an abnormal accumulation of FDG with the standardized uptake value(SUV) max=16.19. A malignant tumor of the chest wall origin was suspected and the tumor was resected with the 3th, 4th, and 5th ribs. Histologically, the tumor was diagnosed as dedifferentiated chondrosarcoma. He died of local recurrence about 5 months after the operation. PMID:27476566

  7. Tuberculosis, advanced - chest x-rays (image)

    MedlinePlus

    Tuberculosis is an infectious disease that causes inflammation, the formation of tubercules and other growths within tissue, ... death. These chest x-rays show advanced pulmonary tuberculosis. There are multiple light areas (opacities) of varying ...

  8. Thymic carcinoma presenting as atypical chest pain.

    PubMed

    Siddiqui, Sadiq; Connelly, Tara; Keita, Luther; Blazkova, Sylvie; Veerasingam, Dave

    2015-01-01

    A 58-year-old woman with a 2-month history of atypical chest pain was referred to the chest pain clinic by the general practitioner. Exercise stress test was positive and subsequent coronary angiogram revealed significant triple vessel disease with left ventricular impairment requiring a coronary artery bypass graft (CABG). The patient had a chest X-ray as part of the preoperative work up. Chest X-ray revealed a large anterior mediastinal mass. Subsequent thorax CT revealed a 7.2 cm anterior mediastinal mass. CT-guided biopsy of the mass revealed the diagnosis of a poorly differentiated thymic basaloid carcinoma. The patient was successfully treated with concomitant surgery involving complete resection of the mass and a CABG procedure. PMID:26607199

  9. Fluoroscopic chest tube insertion and patient care.

    PubMed Central

    Collins, J. D.; Shaver, M. L.; Disher, A. C.; Miller, T. Q.

    1992-01-01

    Catheters and chest tubes may be placed under fluoroscopic control to reduce pleural effusions. This procedure has been adopted as a routine procedure at the UCLA School of Medicine in Los Angeles, California to improve patient care. This technique was modified for the placement of large chest tubes, which can be placed by a radiologist without multiple attempts or complications. Our experience with 2234 patients who underwent this procedure between 1977 and 1990 is described. PMID:1404463

  10. [Compression material].

    PubMed

    Perceau, Géraldine; Faure, Christine

    2012-01-01

    The compression of a venous ulcer is carried out with the use of bandages, and for less exudative ulcers, with socks, stockings or tights. The system of bandages is complex. Different forms of extension and therefore different types of models exist. PMID:22489428

  11. Management of chest trauma: a review.

    PubMed

    Adebonojo, S A

    1993-01-01

    The incidence of chest trauma has increased significantly since the turn of the century especially in developed countries where rapid means of transportation has become part of daily life. Although gunshot wounds (GSWs) were the commonest causes of chest trauma in wartime, road traffic accidents (RTAs) have become the scourge of peacetime and modern civilization. Chest trauma is more common in males during the 2nd to the 5th decades of life with an average age of 40 years reducing their life expectancy by another 40 years at the most productive and active period of their lives. Despite improvement in ambulance service and rapid mobilization of victims from the scene of accident, about 10% of chest injured patients will die on the spot and another 5% die within an hour of reaching the hospital. Of the remaining 85%, five percent will require emergency thoracotomy for various reasons while 80% will respond to resuscitative measures and tube thoracostomy drainage alone. The primary aims in the management of chest trauma are prompt restoration of normal cardiorespiratory functions, control of haemorrhage, treatment of associated injuries and prevention of sepsis. Although the overall survival rate of trauma has improved in recent years, deaths are often due to airway obstruction, exsanguinating haemorrhage, flail chest, tension pneumothorax, cardiac tamponade and associated intracranial, intraabdominal and skeletal injuries. PMID:8398932

  12. [Differential diagnosis "non-cardiac chest pain"].

    PubMed

    Frieling, Thomas

    2015-07-01

    Non cardiac chest pain (NCCP) are recurrent angina pectoris like pain without evidence of coronary heart diesease in conventional diagnostic evaluation. The prevalence of NCCP is up to 70% and may be detected in this order at all levels of the medical health care system (general practitioner, emergency department, chest pain unit, coronary care). Reduction of quality of life in NCCP is comparable, partially even higher compared to cardiac chest pain. Reasons for psychological strain are symptom recurrence in app. 50%, nonspecific diagnosis with resulting uncertainty and insufficient integration of other medical disciplines in diagnostic work-up. Managing of patients with NCCP has to be interdisciplinary because non cardiac causes of chest pain may be found frequently. This are musculosceletal in app. 40%, gastrointestinal in app. 20%, psychiatric in app. 10% and pulmonary and mediastinal diseases in app. 5% of cases. Also gastroenterological expertise is required because here gastroesophageal reflux disease (GERD) in app. 60%, hypercontractile esophageal motility disorders with nutcracker, jackhammer esophagus or distal esophageal spasmus or achalasia in app. 20% and other esophageal alterations (e. g. infectious esophageal inflammation, drug-induced ulcer, rings, webs, eosinophilic esophagits) in app. 30% of cases may be detected as cause of chest pain may. This implicates that regular interdisciplinary round wards and interdisciplinary management of chest pain units are mandatory. PMID:26230070

  13. How to remove a chest drain.

    PubMed

    Allibone, Elizabeth

    2015-10-01

    RATIONALE AND KEY POINTS: This article aims to help nurses to undertake the removal of a chest drain in a safe, effective and patient-centred manner. This procedure requires two practitioners. The chest drain will have been inserted aseptically to remove air, blood, fluid or pus from the pleural cavity. ▶ Chest drains may be small or wide bore depending on the underlying condition and clinical setting. They may be secured with a mattress suture and/or an anchor suture. ▶ Chest drains are usually removed under medical instructions when the patient's lung has inflated, the underlying condition has resolved, there is no evidence of respiratory compromise or failure, and their anticoagulation status has been assessed as satisfactory. ▶ Chest drains secured with a mattress suture should be removed by two practitioners. One practitioner is required to remove the tube and the other to tie the mattress suture (if present) and secure the site. REFLECTIVE ACTIVITY: Clinical skills articles can help update your practice and ensure it remains evidence based. Apply this article to your practice. Reflect on and write a short account of: 1. How reading this article will change your practice. 2. How this article could be used to educate patients with chest drains. Subscribers can upload their reflective accounts at: rcni.com/portfolio . PMID:26443174

  14. Surgical stabilization of traumatic flail chest.

    PubMed Central

    París, F; Tarazona, V; Blasco, E; Cantó, A; Casillas, M; Pastor, J; París, M; Montero, R

    1975-01-01

    Since 1970 we have stabilized the ribs to correct paradoxical movement of the chest wall in chest injuries, using an original technique, in order to avoid as far as possible the need for long-term chest wall stabilization by intermittent positive pressure respiration (IPPR). The technical details of surgical stabilization are described, and the different types of stainless steel struts are shown. Type I was originally used either as an intramedullary nail or as an external brace. Types II and III were designed for external fixation of the strut to the rib. Treatment of 29 patients with severe flail chest, classified into four groups is shown: group I was treated by IPPR, group II by IPPR plus surgical stabilization, group III by surgical stabilization only, and group IV by surgical stabilization after exploratory thoracotomy. The clinical results are discussed. We conclude that surgical stabilization of the paradoxial movement of the chest wall can avoid the use of the respirator or at least reduce the interval of IPPR to a short period during the initial recovery from trauma. Using type III struts, we have obtained stabilization of the flail chest in all cases even in patients with severe anterior paradoxical movement. The patients' tolerance of surgical stainless steel struts was good. Images PMID:1105874

  15. Improved chest recoil using an adhesive glove device for active compression–decompression CPR in a pediatric manikin model☆

    PubMed Central

    Udassi, Jai P.; Udassi, Sharda; Lamb, Melissa A.; Lamb, Kenneth E.; Theriaque, Douglas W.; Shuster, Jonathan J.; Zaritsky, Arno L.; Haque, Ikram U.

    2013-01-01

    Objective We developed an adhesive glove device (AGD) to perform ACD-CPR in pediatric manikins, hypothesizing that AGD-ACD-CPR provides better chest decompression compared to standard (S)-CPR. Design Split-plot design randomizing 16 subjects to test four manikin-technique models in a crossover fashion to AGD-ACD-CPR vs. S-CPR. Healthcare providers performed 5 min of CPR with 30:2 compression:ventilation ratio in the four manikin models: (1) adolescent; (2) child two-hand; (3) child one-hand; and (4) infant two-thumb. Methods Modified manikins recorded compression pressure (CP), compression depth (CD) and decompression depth (DD). The AGD consisted of a modified oven mitt with an adjustable strap; a Velcro patch was sewn to the palmer aspect. The counter Velcro patch was bonded to the anterior chest wall. For infant CPR, the thumbs of two oven mitts were stitched together with Velcro. Subjects were asked to actively pull up during decompression. Subjects’ heart rate (HR), respiratory rate (RR) and recovery time (RT) for HR/RR to return to baseline were recorded. Subjects were blinded to data recordings. Data (mean ± SEM) were analyzed using a two-tailed paired t-test. Significance was defined qualitatively as P ≤ 0.05. Results Mean decompression depth difference was significantly greater with AGD-ACD-CPR compared to S-CPR; 38–75% of subjects achieved chest decompression to or beyond baseline. AGD-ACD-CPR provided 6–12% fewer chest compressions/minute than S-CPR group. There was no significant difference in CD, CP, HR, RR and RT within each group comparing both techniques. Conclusion A simple, inexpensive glove device for ACD-CPR improved chest decompression with emphasis on active pull in manikins without excessive rescuer fatigue. The clinical implication of fewer compressions/minute in the AGD group needs to be evaluated. PMID:19683849

  16. Experimental comparison of Pressure ratio in Alpha and Gamma Stirling cryocoolers with identical compression space volumes and driven simultaneously by a solitary novel compact mechanism

    NASA Astrophysics Data System (ADS)

    Sant, K. D.; Bapat, S. L.

    2015-12-01

    The cryocooler technology is advancing in different ways at a considerable pace to explore cooler applications in diversified field. Stirling cryocoolers are capable to satisfy the contemporary requirements of a low-capacity cooler. A compact mechanism that can drive Stirling cryocooler with larger stroke and thus enhance the cooler performance is the need of the hour. The increase in the stroke will lead to a higher volumetric efficiency. Hence, a cryocooler with larger stroke will experience higher mass flow rate of the working fluid, thereby increasing its ideal cooling capacity. The novel compact drive mechanism that fulfils this need is a promising option in this regards. It is capable of operating more than one cryocoolers of different Stirling configurations simultaneously. This arrangement makes it possible to compare different Stirling cryocoolers on the basis of pressure ratio obtained experimentally. The preliminary experimental results obtained in this regard are presented here. The initial experimentation is carried out on two Alpha Stirling units driven simultaneously by the novel compact mechanism. The pressure ratio obtained during the initial stages is 1.3538, which is enhanced to 1.417 by connecting the rear volumes of the compressor pistons to each other. The fact that annular leak across the expander pistons due to high pressure ratio affects the cryocooler performance, generates the need to separate the expansion space from bounce space. This introduces a Gamma configuration that is operated simultaneously with one of the existing Alpha units by same drive mechanism and having identical compression space volume. The results obtained for pressure ratio in both these units prove the concept that cooling capacity of Alpha configuration exceeds that of Gamma under similar operating conditions. This has been observed at 14 bar and 20 bar charge pressures during the preliminary experimentation. These results are presented in this paper. Thus, the

  17. The role of molecular motors in the mechanics of active gels and the effects of inertia, hydrodynamic interaction and compressibility in passive microrheology

    NASA Astrophysics Data System (ADS)

    Uribe, Andres Cordoba

    The mechanical properties of soft biological materials are essential to their physiological function and cannot easily be duplicated by synthetic materials. The study of the mechanical properties of biological materials has lead to the development of new rheological characterization techniques. In the technique called passive microbead rheology, the positional autocorrelation function of a micron-sized bead embedded in a viscoelastic fluid is used to infer the dynamic modulus of the fluid. Single particle microrheology is limited to fluids were the microstructure is much smaller than the size of the probe bead. To overcome this limitation in two-bead microrheology the cross-correlated thermal motion of pairs of tracer particles is used to determine the dynamic modulus. Here we present a time-domain data analysis methodology and generalized Brownian dynamics simulations to examine the effects of inertia, hydrodynamic interaction, compressibility and non-conservative forces in passive microrheology. A type of biological material that has proven specially challenging to characterize are active gels. They are formed by semiflexible polymer filaments driven by motor proteins that convert chemical energy from the hydrolysis of adenosine triphosphate (ATP) to mechanical work and motion. Active gels perform essential functions in living tissue. Here we introduce a single-chain mean-field model to describe the mechanical properties of active gels. We model the semiflexible filaments as bead-spring chains and the molecular motors are accounted for by using a mean-field approach. The level of description of the model includes the end-to-end length and attachment state of the filaments, and the motor-generated forces, as stochastic state variables which evolve according to a proposed differential Chapman-Kolmogorov equation. The model allows accounting for physics that are not available in models that have been postulated on coarser levels of description. Moreover it allows

  18. [Influences of chest deformation by upper abdominal retractor on respiratory system impedance during abdominal surgery].

    PubMed

    Oka, T; Ozawa, Y; Sato, J

    1999-02-01

    The present study was carried out to clarify the effects of chest deformation by upper abdominal retractor on respiratory system impedance during abdominal surgery. We measured the impedances of respiratory system (RS), lung, and chest wall (CW) in nine anesthetized paralyzed subjects employing a pseudorandom noise forced volume oscillation technique. These measurements were performed before and after the lifting chest wall by upper abdominal retractor. The effects of chest deformation was significant on the impedances of RS, lung, while no discernible effect was found in CW impedance. Lifting chest wall decreased RS resistance which was totally accounted for by the decrease in lung resistance, whereas the lifting did not affect reactance in either RS or lung. The mathematical modeling showed the significant lifting effect on the resistance of the parenchyma. In conclusion, change in RS mechanics produced by chest deformation by upper abdominal retractor is dominated in lung but not in CW. Among the lung mechanical components, parenchyma is the primary site of the lifting effect. PMID:10087819

  19. 46 CFR 196.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Portable magazine chests. 196.37-47 Section 196.37-47... Markings for Fire and Emergency Equipment, etc. § 196.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: PORTABLE MAGAZINE CHEST — FLAMMABLE —...

  20. 46 CFR 196.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Portable magazine chests. 196.37-47 Section 196.37-47... Markings for Fire and Emergency Equipment, etc. § 196.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: PORTABLE MAGAZINE CHEST — FLAMMABLE —...

  1. 46 CFR 196.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Portable magazine chests. 196.37-47 Section 196.37-47... Markings for Fire and Emergency Equipment, etc. § 196.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: PORTABLE MAGAZINE CHEST — FLAMMABLE —...

  2. 42 CFR 37.4 - Plans for chest roentgenographic examinations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Plans for chest roentgenographic examinations. 37.4... EXAMINATIONS SPECIFICATIONS FOR MEDICAL EXAMINATIONS OF UNDERGROUND COAL MINERS Chest Roentgenographic Examinations § 37.4 Plans for chest roentgenographic examinations. (a) Every plan for chest...

  3. 46 CFR 196.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Portable magazine chests. 196.37-47 Section 196.37-47... Markings for Fire and Emergency Equipment, etc. § 196.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: PORTABLE MAGAZINE CHEST — FLAMMABLE —...

  4. 42 CFR 37.4 - Plans for chest roentgenographic examinations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Plans for chest roentgenographic examinations. 37.4... EXAMINATIONS SPECIFICATIONS FOR MEDICAL EXAMINATIONS OF UNDERGROUND COAL MINERS Chest Roentgenographic Examinations § 37.4 Plans for chest roentgenographic examinations. (a) Every plan for chest...

  5. 46 CFR 196.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Portable magazine chests. 196.37-47 Section 196.37-47... Markings for Fire and Emergency Equipment, etc. § 196.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: PORTABLE MAGAZINE CHEST — FLAMMABLE —...

  6. Initial clinical evaluation of stationary digital chest tomosynthesis

    NASA Astrophysics Data System (ADS)

    Hartman, Allison E.; Shan, Jing; Wu, Gongting; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping; Heath, Michael; Wang, Xiaohui; Foos, David

    2016-03-01

    Computed Tomography (CT) is the gold standard for image evaluation of lung disease, including lung cancer and cystic fibrosis. It provides detailed information of the lung anatomy and lesions, but at a relatively high cost and high dose of radiation. Chest radiography is a low dose imaging modality but it has low sensitivity. Digital chest tomosynthesis (DCT) is an imaging modality that produces 3D images by collecting x-ray projection images over a limited angle. DCT is less expensive than CT and requires about 1/10th the dose of radiation. Commercial DCT systems acquire the projection images by mechanically scanning an x-ray tube. The movement of the tube head limits acquisition speed. We recently demonstrated the feasibility of stationary digital chest tomosynthesis (s-DCT) using a carbon nanotube (CNT) x-ray source array in benchtop phantom studies. The stationary x-ray source allows for fast image acquisition. The objective of this study is to demonstrate the feasibility of s-DCT for patient imaging. We have successfully imaged 31 patients. Preliminary evaluation by board certified radiologists suggests good depiction of thoracic anatomy and pathology.

  7. Cardio-embolic stroke following remote blunt chest trauma.

    PubMed

    Arora, Sonali; Atreya, Auras R; Penumetsa, Srikanth C; Hiser, William L

    2013-03-01

    A cardio-embolic stroke as a sequela of remote blunt chest trauma is a rare clinical presentation. Blunt chest trauma can cause various acute cardiac complications like arrhythmias, cardiac contusion etc. However, delayed consequences such as left ventricular thrombus resulting in thromboembolic phenomena are reported infrequently. A 30-year-old healthy man presented to an outside facility with transient neurological deficits. An MRI brain showed lesions suggestive of embolic etiology. A trans-thoracic echocardiogram (TTE) showed a 1.5 × 1.5 cm mass present in the left ventricular (LV) apex. Patient was transferred to our institution for cardiac surgery evaluation. On detailed questioning, he reported an incident of blunt chest trauma during a martial arts exhibition fight that took place 2 years back. Given this history, a cardiac catheterization was done, which showed 30% stenosis in mid-left anterior descending artery (LAD) without any other significant obstructive lesion. A trans-esophageal echocardiogram (TEE) showed akinesis of the LV apex and confirmed TTE finding of a mass, consistent with an apical thrombus. Surgery was deferred and patient was started on anticoagulation. A cardiac MRI done 2 weeks later showed evidence of apical infarction in the LAD territory. LAD is the most commonly affected coronary vessel by blunt traumatic injuries, likely due to its vulnerable anatomical position on the anterior aspect of the heart. A variety of mechanisms including intimal tear, rupture and spasm have been implicated in the pathogenesis of myocardial infarction after blunt chest trauma. PMID:24023477

  8. Compressed Genotyping

    PubMed Central

    Erlich, Yaniv; Gordon, Assaf; Brand, Michael; Hannon, Gregory J.; Mitra, Partha P.

    2011-01-01

    Over the past three decades we have steadily increased our knowledge on the genetic basis of many severe disorders. Nevertheless, there are still great challenges in applying this knowledge routinely in the clinic, mainly due to the relatively tedious and expensive process of genotyping. Since the genetic variations that underlie the disorders are relatively rare in the population, they can be thought of as a sparse signal. Using methods and ideas from compressed sensing and group testing, we have developed a cost-effective genotyping protocol to detect carriers for severe genetic disorders. In particular, we have adapted our scheme to a recently developed class of high throughput DNA sequencing technologies. The mathematical framework presented here has some important distinctions from the ’traditional’ compressed sensing and group testing frameworks in order to address biological and technical constraints of our setting. PMID:21451737

  9. Use of a titanium alloy (Chest Way) in the surgical stabilization of flail chest.

    PubMed

    Nakagawa, Tomoki; Matsuzaki, Tomohiko; Aruga, Naohiro; Imamura, Naoko; Hamanaka, Rurika; Ikoma, Yoichiro; Masuda, Ryota; Iwazaki, Masayuki

    2016-09-01

    To avoid the complications of internal pneumatic stabilization for flail chest, we performed stabilization of the chest wall with a metal bar using the Nuss procedure. Here, we used a highly elastic lightweight biocompatible titanium alloy Chest Way (Solve Corporation, Kanagawa, Japan), enabling magnetic resonance imaging. The patient was a 37-year-old man who sustained injuries in a car crash. Gradually increasing subcutaneous emphysema was present. Bilateral pleural drainage and tracheal intubation were conducted on the scene, and a peripheral venous line was established. The patient was then transferred to our hospital by helicopter. A titanium alloy Chest Way was inserted to manage his flail chest accompanied by multiple rib fractures on the left side. Two days later, artificial respiration was no longer required. PMID:26096325

  10. Micro-anatomical response of cartilage-on-bone to compression: mechanisms of deformation within and beyond the directly loaded matrix

    PubMed Central

    Thambyah, Ashvin; Broom, Neil

    2006-01-01

    The biomechanical function of articular cartilage relies crucially on its integration with both the subchondral bone and the wider continuum of cartilage beyond the directly loaded contact region. This study was aimed at visualizing, at the microanatomical level, the deformation response of cartilage including that of the non-directly loaded continuum. Cartilage-on-bone samples from bovine patellae were loaded in static compression until a near-equilibrium deformation was achieved, and then chemically fixed in this deformed state. Full-depth cartilage–bone sections, incorporating the indentation profile and beyond, were studied in their fully hydrated state using differential interference contrast microscopy. Morphometric measurements of the indented profile were used in combination with a force analysis of the tangential layer to investigate the extent to which the applied force is attenuated in moving away from the directly loaded region. This study provides microscopic evidence of a structure-related response in the transitional zone of the cartilage matrix. It is manifested as an intense chevron-type shear discontinuity arising from the constraints provided by both the strain-limiting articular surface and the osteochondral attachment. The discontinuity persists well into the non-directly loaded continuum of cartilage and is proposed as a force attenuation mechanism. The structural and biomechanical analyses presented in this study emphasize the important role of the complex microanatomy of cartilage, highlighting the interconnectivity and optimal recruitment of the load-bearing elements throughout the zonally differentiated cartilage depth. PMID:17062019

  11. Dynamic chest radiography: flat-panel detector (FPD) based functional X-ray imaging.

    PubMed

    Tanaka, Rie

    2016-07-01

    Dynamic chest radiography is a flat-panel detector (FPD)-based functional X-ray imaging, which is performed as an additional examination in chest radiography. The large field of view (FOV) of FPDs permits real-time observation of the entire lungs and simultaneous right-and-left evaluation of diaphragm kinetics. Most importantly, dynamic chest radiography provides pulmonary ventilation and circulation findings as slight changes in pixel value even without the use of contrast media; the interpretation is challenging and crucial for a better understanding of pulmonary function. The basic concept was proposed in the 1980s; however, it was not realized until the 2010s because of technical limitations. Dynamic FPDs and advanced digital image processing played a key role for clinical application of dynamic chest radiography. Pulmonary ventilation and circulation can be quantified and visualized for the diagnosis of pulmonary diseases. Dynamic chest radiography can be deployed as a simple and rapid means of functional imaging in both routine and emergency medicine. Here, we focus on the evaluation of pulmonary ventilation and circulation. This review article describes the basic mechanism of imaging findings according to pulmonary/circulation physiology, followed by imaging procedures, analysis method, and diagnostic performance of dynamic chest radiography. PMID:27294264

  12. Investigation of Esophageal Sensation and Biomechanical Properties in Functional Chest Pain

    PubMed Central

    Nasr, Issam; Attaluri, Ashok; Hashmi, Syed; Gregersen, Hans; Rao, Satish S.C.

    2010-01-01

    OBJECTIVES There is limited and conflicting data regarding the role of esophageal hypersensitivity in the pathogenesis of functional chest pain (FCP). We examined esophageal sensori-motor properties, mechanics and symptoms in subjects with FCP. METHODS Esophageal balloon distension test (EBDT) was performed using impedance planimetry in 189 (m/f = 57/132) consecutive subjects with noncardiac, non-reflux chest pain, and 36 (m/f = 16/20) healthy controls. The biomechanical and sensory properties of subjects with and without esophageal hypersensitivity were compared to controls. The frequency, intensity and duration of chest pain were assessed. RESULTS: 143 (75 %) subjects had esophageal hypersensitivity and 46 (25%) had normal sensitivity. Typical chest pain was reproduced in 105/143 (74%) subjects. Subjects with hypersensitivity demonstrated larger cross-sectional area (CSA) (p<0.001), decreased esophageal wall strain (p<0.001) and distensibility (p<0.001), and lower thresholds for perception (p<0.01), discomfort (p<0.01) and pain (p<0.01) compared to those without hypersensitivity or healthy controls. Chest pain scores (mean ± SD) for frequency, intensity and duration were 2.5 ± 0.3, 2.2 ± 0.2 and 2.2 ± 0.2 respectively, and were similar between the two patient groups. CONCLUSIONS 75% of subjects with FCP demonstrate esophageal hypersensitivity. Visceral hyperalgesia and sensori-motor dysfunction of the esophagus play a key role in the pathogenesis of chest pain. PMID:20067548

  13. A Murine Closed-chest Model of Myocardial Ischemia and Reperfusion

    PubMed Central

    Kim, Se-Chan; Boehm, Olaf; Meyer, Rainer; Hoeft, Andreas; Knüfermann, Pascal; Baumgarten, Georg

    2012-01-01

    Surgical trauma by thoracotomy in open-chest models of coronary ligation induces an immune response which modifies different mechanisms involved in ischemia and reperfusion. Immune response includes cytokine expression and release or secretion of endogenous ligands of innate immune receptors. Activation of innate immunity can potentially modulate infarct size. We have modified an existing murine closed-chest model using hanging weights which could be useful for studying myocardial pre- and postconditioning and the role of innate immunity in myocardial ischemia and reperfusion. This model allows animals to recover from surgical trauma before onset of myocardial ischemia. Volatile anesthetics have been intensely studied and their preconditioning effect for the ischemic heart is well known. However, this protective effect precludes its use in open chest models of coronary artery ligation. Thus, another advantage could be the use of the well controllable volatile anesthetics for instrumentation in a chronic closed-chest model, since their preconditioning effect lasts up to 72 hours. Chronic heart diseases with intermittent ischemia and multiple hit models are other possible applications of this model. For the chronic closed-chest model, intubated and ventilated mice undergo a lateral blunt thoracotomy via the 4th intercostal space. Following identification of the left anterior descending a ligature is passed underneath the vessel and both suture ends are threaded through an occluder. Then, both suture ends are passed through the chest wall, knotted to form a loop and left in the subcutaneous tissue. After chest closure and recovery for 5 days, mice are anesthetized again, chest skin is reopened and hanging weights are hooked up to the loop under ECG control. At the end of the ischemia/reperfusion protocol, hearts can be stained with TTC for infarct size assessment or undergo perfusion fixation to allow morphometric studies in addition to histology and

  14. Redox Imbalance in the Peripheral Mechanism Underlying the Mirror-Image Neuropathic Pain Due to Chronic Compression of Dorsal Root Ganglion.

    PubMed

    Lv, H; Chen, H; Xu, J J; Jiang, Y S; Shen, Y J; Zhou, S Z; Xu, H; Xiong, Y C

    2016-05-01

    Reactive oxygen species (ROS) play a critical role in the pathogenesis of neuropathic pain, but few studies have examined the role of oxidative stress in the mirror-image neuropathic pain (MINP). The present study was to investigate the role of ROS in MINP caused by chronic compression of the dorsal root ganglion (DRG) (CCD) in a rat model. SD rats were randomly divided into sham group and CCD group. CCD was conducted to induce MINP. CCD rats were intraperitoneally injected with α-Phenyl-N-tert-butyl-nitrone (PBN) at 7 days after surgery. Paw withdrawal mechanical threshold (PWMT) was measured at -1, 1, 3, 5 and 7 days after surgery in sham group and CCD group, and at 8 time points after PBN injection. Rats were sacrificed at 3 and 7 days after surgery in sham group and CCD group and at 0.5 and 2 h after PBN injection, and the superoxide dismutase (SOD) and catalase activities, as well as hydrogen peroxide (H2O2) and malonaldehyde (MDA) contents were determined in the contralateral DRGs. Results showed bilateral PWMT reduced significantly in sham group and CCD group, but it returned to nearly normal level in sham group. MDA content, H2O2 content and SOD activity increased significantly, while catalase activity remained unchanged in CCD rats. PBN at 100 mg/kg significantly attenuated bilateral mechanical hyperalgesia accompanied by the improvement of oxidative stress in the contralateral DRGs. Our results demonstrate that ROS produced in the contralateral DRG are involved in the pathogenesis of CCD induced MINP, and ROS scavenger may be a promising drug for the therapy of MINP. PMID:26471165

  15. The expanded role of extracellular matrix patch in malignant and non-malignant chest wall reconstruction in thoracic surgery†

    PubMed Central

    George, Robert S.; Kostopanagiotou, Kostas; Papagiannopoulos, Kostas

    2014-01-01

    OBJECTIVES The extracellular matrix (XCM Biologic Tissue Matrix) is a non-cross-linked 3D patch derived from porcine dermis. Once implanted, it is infiltrated by recipient's cells and becomes incorporated in the repair. Here, we report the first series of using this device for chest wall reconstruction. METHODS The XCM Biologic Tissue Matrix was utilized to provide the restoration of chest wall defects. It was used either alone or in conjunction with the Synthes titanium system to provide additional support. The decision was made intraoperatively. RESULTS Since April 2010, 21 (12 females) patients received the device. Average age at operation was 47 ± 17 years. Eleven (52%) patients had the patch inserted alone, while the remaining 10 received it in combination with another implantable medical device. The biological tissue matrix was used to reconstruct chest wall defects in cancer involving chest wall (n = 9), chest wall deformity (n = 6), chest wall hernia (n = 5) and chest wall repair following empyema drainage (n = 1). Complications were witnessed in 3 patients receiving the combined XCM and Synthes bar mechanisms; infection (n = 2) and bar displacement and infection (n = 1). CONCLUSIONS The XCM patch can be safely used to provide the strength required for chest wall reconstruction and to replace previously infected reconstructions. PMID:24263580

  16. Treatment of Morbidity with Atypical Chest Pain

    PubMed Central

    Cott, Arthur

    1987-01-01

    The appropriate management of atypical chest pain requires an integration of medical and behavioural treatments. Unnecessary medicalization can increase morbidity. A sensitivity to the behavioural factors contributing to symptoms and disability may reduce both. The purpose of this paper is to provide physicians with a cognitive-behavioural perspective of the nature of morbidity and disability associated with chronic chest discomfort; some strategies for detecting heretofore unsuspected disability associated with chronic chest pain and related discomfort in patients with organic findings (both cardiac and non-cardiac), as well those with no identifiable disease process or organic cause; and some simple behavioural and cognitive-behavioural therapeutic techniques for treating and preventing such problems. PMID:21263912

  17. Enhancement of chest radiographs using eigenimage processing

    NASA Astrophysics Data System (ADS)

    Bones, Philip J.; Butler, Anthony P. H.; Hurrell, Michael

    2006-08-01

    Frontal chest radiographs ("chest X-rays") are routinely used by medical personnel to assess patients for a wide range of suspected disorders. Often large numbers of images need to be analyzed. Furthermore, at times the images need to analyzed ("reported") when no radiological expert is available. A system which enhances the images in such a way that abnormalities are more obvious is likely to reduce the chance that an abnormality goes unnoticed. The authors previously reported the use of principal components analysis to derive a basis set of eigenimages from a training set made up of images from normal subjects. The work is here extended to investigate how best to emphasize the abnormalities in chest radiographs. Results are also reported for various forms of image normalizing transformations used in performing the eigenimage processing.

  18. Systemic Air Embolism Associated with Pleural Pigtail Chest Tube Insertion

    PubMed Central

    Alkhankan, Emad; Nusair, Ahmad; Mazagri, Rida

    2016-01-01

    Pleural pigtail catheter placement is associated with many complications including pneumothorax, hemorrhage, and chest pain. Air embolism is a known but rare complication of pleural pigtail catheter insertion and has a high risk of occurrence with positive pressure ventilation. In this case report, we present a 50-year-old male with bilateral pneumonia who developed a pneumothorax while on mechanical ventilation with continuous positive airway pressure mode. During the placement of the pleural pigtail catheter to correct the pneumothorax, the patient developed a sudden left sided body weakness and became unresponsive. An air embolism was identified in the right main cerebral artery, which was fatal.

  19. Derivation and Validation of Two Decision Instruments for Selective Chest CT in Blunt Trauma: A Multicenter Prospective Observational Study (NEXUS Chest CT)

    PubMed Central

    Rodriguez, Robert M.; Langdorf, Mark I.; Nishijima, Daniel; Baumann, Brigitte M.; Hendey, Gregory W.; Medak, Anthony J.; Raja, Ali S.; Allen, Isabel E.; Mower, William R.

    2015-01-01

    Background Unnecessary diagnostic imaging leads to higher costs, longer emergency department stays, and increased patient exposure to ionizing radiation. We sought to prospectively derive and validate two decision instruments (DIs) for selective chest computed tomography (CT) in adult blunt trauma patients. Methods and Findings From September 2011 to May 2014, we prospectively enrolled blunt trauma patients over 14 y of age presenting to eight US, urban level 1 trauma centers in this observational study. During the derivation phase, physicians recorded the presence or absence of 14 clinical criteria before viewing chest imaging results. We determined injury outcomes by CT radiology readings and categorized injuries as major or minor according to an expert-panel-derived clinical classification scheme. We then employed recursive partitioning to derive two DIs: Chest CT-All maximized sensitivity for all injuries, and Chest CT-Major maximized sensitivity for only major thoracic injuries (while increasing specificity). In the validation phase, we employed similar methodology to prospectively test the performance of both DIs. We enrolled 11,477 patients—6,002 patients in the derivation phase and 5,475 patients in the validation phase. The derived Chest CT-All DI consisted of (1) abnormal chest X-ray, (2) rapid deceleration mechanism, (3) distracting injury, (4) chest wall tenderness, (5) sternal tenderness, (6) thoracic spine tenderness, and (7) scapular tenderness. The Chest CT-Major DI had the same criteria without rapid deceleration mechanism. In the validation phase, Chest CT-All had a sensitivity of 99.2% (95% CI 95.4%–100%), a specificity of 20.8% (95% CI 19.2%–22.4%), and a negative predictive value (NPV) of 99.8% (95% CI 98.9%–100%) for major injury, and a sensitivity of 95.4% (95% CI 93.6%–96.9%), a specificity of 25.5% (95% CI 23.5%–27.5%), and a NPV of 93.9% (95% CI 91.5%–95.8%) for either major or minor injury. Chest CT-Major had a sensitivity

  20. Noninvasive ventilation in large postoperative flail chest.

    PubMed

    Piastra, Marco; De Luca, Daniele; Zorzi, Giulia; Ruggiero, Antonio; Antonelli, Massimo; Conti, Giorgio; Pietrini, Domenico

    2008-12-01

    An 11-year-old male developed a severe respiratory failure due to a iatrogenic flail chest following a surgery for removing a large chest wall area. A rare Ewing sarcoma was histologically diagnosed and intensive chemotherapy was administered. Postoperatively, because of the failure in ventilation weaning, the patient was electively extubated and noninvasive positive pressure ventilation through face-mask was provided. Respiratory support avoided asynchronous paradoxical movements and achieved pneumatic stabilization. Clinical and respiratory improvement allowed a successful weaning from ventilator. PMID:18798557

  1. Misdiagnosed Chest Pain: Spontaneous Esophageal Rupture

    PubMed Central

    Inci, Sinan; Gundogdu, Fuat; Gungor, Hasan; Arslan, Sakir; Turkyilmaz, Atila; Eroglu, Atila

    2013-01-01

    Chest pain is one of themost common complaints expressed by patients presenting to the emergency department, and any initial evaluation should always consider life-threatening causes. Esophageal rupture is a serious condition with a highmortality rate. If diagnosed, successful therapy depends on the size of the rupture and the time elapsed between rupture and diagnosis.We report on a 41-year-old woman who presented to the emergency department complaining of left-sided chest pain for two hours. PMID:27122690

  2. [Coronary artery dissection following blunt chest trauma].

    PubMed

    Seven, Ekim; Henningsen, Kristoffer; Abildgaard, Ulrik

    2015-03-16

    A previously healthy 38-year-old man was admitted to hospital with chest pain. The day before the patient had been to a karate session and had received multiple punches and kicks to the chest region. An ECG showed Q-waves in V1 and V2 and flattening of the T-waves in V1-V6. Levels of cardiac enzyme markers were elevated. The patient subsequently underwent coronary angiography with supplemental optical coherence tomography that revealed a bifurcate dissection involving the proximal parts of left ramus interventricularis anterior and circumflex coronary artery. Two drug-eluting stents were implanted with good angiographic result. PMID:25786846

  3. An unusual case of left renal artery compression: a rare type of median arcuate ligament syndrome.

    PubMed

    Arazińska, Agata; Polguj, Michał; Wojciechowski, Andrzej; Trębiński, Łukasz; Stefańczyk, Ludomir

    2016-04-01

    Compression from median arcuate ligament was observed during multidetector 64-row computed tomography in a Caucasian 30-year-old female. The patient was referred for examination to exclude anatomical pathologies causing hypertension. The examination demonstrated that left renal artery, which had its origin in the chest (at the level of upper one-third of Th12), was compressed as it passed by median arcuate ligament of the diaphragm. In addition, aortic compression and kinked shape was also revealed. PMID:25940812

  4. Research of Electrical Response Communication Parameters on the Pulse Mechanical Impact with the Stress-Strain State of Concrete Under Uniaxial Compression

    NASA Astrophysics Data System (ADS)

    Dann, D.; Demikhova, A.; Fursa, T.; Kuimova, M.

    2014-10-01

    The article presents the results of research of the electrical response on elastic impact excitation of heavy concrete samples under uniaxial compression. In this paper we recorded and analyzed electrical responses during uniaxial compression of concrete samples with a constant velocity. Studies have shown that in the process of uniaxial compression of concrete samples, the transformation of amplitude-frequency characteristics of the electrical response is observed. The stage of elastic deformation of concrete samples is characterized by a centershift of gravity of the spectrum of the electrical response towards lower frequencies. Dramatic centershift of gravity of the spectrum of the electrical response to the high frequency region characterizes the beginning of fracturing.

  5. Fatal right coronary artery rupture following blunt chest trauma: detection by postmortem selective coronary angiography.

    PubMed

    Inokuchi, Go; Makino, Yohsuke; Motomura, Ayumi; Chiba, Fumiko; Torimitsu, Suguru; Hoshioka, Yumi; Iwase, Hirotaro

    2016-05-01

    Coronary artery injury is a rare complication following blunt chest trauma (BCT), and can be fatal. Here we report findings on postmortem selective coronary angiography of right coronary artery rupture after an assault involving blunt trauma to the chest. A woman in her 60s died after her son stomped on her chest. There were no appreciable signs of injury on external examination, and cause of death could not be determined by postmortem computed tomography (PMCT). Internal findings indicated that an external force had been applied to the anterior chest, as evidenced by subcutaneous hemorrhage and pericardial and cardiac contusions. Postmortem coronary angiography revealed irregularity of the intima and of the fat tissue surrounding the proximal part of the right coronary artery associated with a local filling defect. Histopathological examination suggested coronary rupture with dissection of the tunica media and compression of the lumen cavity. The key points in the present case are that no fatal injuries could be determined on external examination, and the heart and coronary artery injuries were not evident on PMCT. Criminality might be overlooked in such cases, as external investigation at the crime scene would be inadequate and could result in a facile diagnosis of cause of death. This is the first report of coronary artery rupture with dissection that was detected by CT coronary angiography, and provides helpful findings for reaching an appropriate decision both forensically and clinically. PMID:26126482

  6. Chest wall reconstruction after resection using hernia repair piece

    PubMed Central

    Wu, Yimin; Zhang, Guofei; Zhu, Zhouyu

    2016-01-01

    Reconstruction of chest wall tumor is very important link of chest wall tumor resection. Many implants have been reported to be used to reconstruct the chest wall, such as steelwire, titanium mesh and polypropylene mesh. It is really hard for clinicians to decide which implant is the best one to replace the chest wall. We herein report a 68-year-old man who had underwent a chest wall reconstruction with a hernia repair piece and a Dacron hernia repair piece. The patient has maintained an excellent cosmetic and functional outcome since surgery, which proves that the hernia piece still has its place in reconstruction of chest wall. PMID:27293859

  7. Compression and venous ulcers.

    PubMed

    Stücker, M; Link, K; Reich-Schupke, S; Altmeyer, P; Doerler, M

    2013-03-01

    Compression therapy is considered to be the most important conservative treatment of venous leg ulcers. Until a few years ago, compression bandages were regarded as first-line therapy of venous leg ulcers. However, to date medical compression stockings are the first choice of treatment. With respect to compression therapy of venous leg ulcers the following statements are widely accepted: 1. Compression improves the healing of ulcers when compared with no compression; 2. Multicomponent compression systems are more effective than single-component compression systems; 3. High compression is more effective than lower compression; 4. Medical compression stockings are more effective than compression with short stretch bandages. Healed venous leg ulcers show a high relapse rate without ongoing treatment. The use of medical stockings significantly reduces the amount of recurrent ulcers. Furthermore, the relapse rate of venous leg ulcers can be significantly reduced by a combination of compression therapy and surgery of varicose veins compared with compression therapy alone. PMID:23482538

  8. Adenocarcinoma - chest x-ray (image)

    MedlinePlus

    This chest x-ray shows adenocarcinoma of the lung. There is a rounded light spot in the right upper lung (left side ... density. Diseases that may cause this type of x-ray result would be tuberculous or fungal granuloma, and ...

  9. Coccidioidomycosis - chest x-ray (image)

    MedlinePlus

    This chest x-ray shows the affects of a fungal infection, coccidioidomycosis. In the middle of the left lung (seen on the ... defined borders. Other diseases that may explain these x-ray findings include lung abscesses, chronic pulmonary tuberculosis, chronic ...

  10. Salmonella typhimurium abscess of the chest wall

    PubMed Central

    Tonziello, Gilda; Valentinotti, Romina; Arbore, Enrico; Cassetti, Paolo; Luzzati, Roberto

    2013-01-01

    Patient: Male, 73 Final Diagnosis: Salmonella typhimurium abscess of the chest wall Symptoms: — Medication: Ciprofloxacin Clinical Procedure:— Specialty: Infectious Diseases Objective: Unusual clinical course Background: Non-typhoid Salmonella extra-intestinal infections usually develop in infants and in adult patients with pre-existing predisposing conditions. Blood stream infections and urinary tract infections are the most common clinical presentations, but other sites of infection may be involved as well. Case Report: We describe a case of invasive salmonellosis caused by Salmonella typhimurium involving the chest wall in a 73-year-old man. The patient had suffered from gastroenteritis followed by left basal pneumonia with pleural effusion 7 weeks before. The CT scan of the chest wall showed a pericostal abscess with shirt-stud morphology near the left last cartilaginous arch. The abscess was surgically drained and patient was cured after a 40-day ciprofloxacin treatment. Conclusions: A review of the literature on extra-intestinal non-typhoid salmonellosis shows that pleuropulmonary and soft-tissue infections are uncommon. We argue that non-typhoid Salmonella might be considered as a possible cause of chest wall abscess in individuals with recent history of gastroenteritis complicated by pneumonia and pleural effusion. PMID:24298305

  11. [Optimal beam quality for chest digital radiography].

    PubMed

    Oda, Nobuhiro; Tabata, Yoshito; Nakano, Tsutomu

    2014-11-01

    To investigate the optimal beam quality for chest computed radiography (CR), we measured the radiographic contrast and evaluated the image quality of chest CR using various X-ray tube voltages. The contrast between lung and rib or heart increased on CR images obtained by lowering the tube voltage from 140 to 60 kV, but the degree of increase was less. Scattered radiation was reduced on CR images with a lower tube voltage. The Wiener spectrum of CR images with a low tube voltage showed a low value under identical conditions of amount of light stimulated emission. The quality of chest CR images obtained using a lower tube voltage (80 kV and 100 kV) was evaluated as being superior to those obtained with a higher tube voltage (120 kV and 140 kV). Considering the problem of tube loading and exposure in clinical applications, a tube voltage of 90 to 100 kV (0.1 mm copper filter backed by 0.5 mm aluminum) is recommended for chest CR. PMID:25410333

  12. Unsupervised segmentation of lungs from chest radiographs

    NASA Astrophysics Data System (ADS)

    Ghosh, Payel; Antani, Sameer K.; Long, L. Rodney; Thoma, George R.

    2012-03-01

    This paper describes our preliminary investigations for deriving and characterizing coarse-level textural regions present in the lung field on chest radiographs using unsupervised grow-cut (UGC), a cellular automaton based unsupervised segmentation technique. The segmentation has been performed on a publicly available data set of chest radiographs. The algorithm is useful for this application because it automatically converges to a natural segmentation of the image from random seed points using low-level image features such as pixel intensity values and texture features. Our goal is to develop a portable screening system for early detection of lung diseases for use in remote areas in developing countries. This involves developing automated algorithms for screening x-rays as normal/abnormal with a high degree of sensitivity, and identifying lung disease patterns on chest x-rays. Automatically deriving and quantitatively characterizing abnormal regions present in the lung field is the first step toward this goal. Therefore, region-based features such as geometrical and pixel-value measurements were derived from the segmented lung fields. In the future, feature selection and classification will be performed to identify pathological conditions such as pulmonary tuberculosis on chest radiographs. Shape-based features will also be incorporated to account for occlusions of the lung field and by other anatomical structures such as the heart and diaphragm.

  13. Uncommon Flaps for Chest Wall Reconstruction

    PubMed Central

    Matros, Evan; Disa, Joseph J.

    2011-01-01

    The omentum, external oblique musculocutaneous, and thoracoepigastric flaps are uncommonly used for chest wall reconstruction. Nevertheless, awareness and knowledge of these flaps is essential for reconstructive surgeons because they fill specific niche indications or serve as lifeboats when workhorse flaps are unavailable. The current report describes the anatomic basis, technical aspects of flap elevation, and indications for these unusual flaps. PMID:22294943

  14. [Functional Outcome after Chest Wall Stabilisation].

    PubMed

    Kyriss, T; Lenz, U; Friedel, G

    2016-09-01

    This overview reviews the current literature to compare the functional results after surgical and conservative treatment of patients with flail chest and multiple rib fractures. Regarding functional aspects, patients in the early phase after a thoracic trauma are those that benefit most from the stabilisation of the chest wall by internal fixation of the ribs. Patients recover faster from restrictive respiratory disorders, have less pain and return to the workplace earlier after an operation compared with those that receive conservative treatment. In the medium term, however, patients that are treated conservatively also achieve normal pulmonary function values and become free of pain. The period of convalescence after blunt thoracic trauma is generally underestimated. Future studies of the functional outcome after severe chest injuries should take this into account and the development of functional parameters should be monitored for at least 24 months. A prospective data collection of early and long-term surgical results in registries would be suitable to evaluate benefits and indications of chest wall stabilisation. PMID:27607891

  15. 30 CFR 56.6133 - Powder chests.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd., Room 2436, Arlington, Virginia 22209... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Powder chests. 56.6133 Section 56.6133 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Explosives Storage § 56.6133...

  16. 30 CFR 56.6133 - Powder chests.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... CFR part 51. Copies are available at MSHA, 1100 Wilson Blvd., Room 2436, Arlington, Virginia 22209... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Powder chests. 56.6133 Section 56.6133 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Explosives Storage § 56.6133...

  17. Shock compression of polyvinyl chloride

    NASA Astrophysics Data System (ADS)

    Neogi, Anupam; Mitra, Nilanjan

    2016-04-01

    This study presents shock compression simulation of atactic polyvinyl chloride (PVC) using ab-initio and classical molecular dynamics. The manuscript also identifies the limits of applicability of classical molecular dynamics based shock compression simulation for PVC. The mechanism of bond dissociation under shock loading and its progression is demonstrated in this manuscript using the density functional theory based molecular dynamics simulations. The rate of dissociation of different bonds at different shock velocities is also presented in this manuscript.

  18. [Mechanical resuscitation assist devices].

    PubMed

    Fischer, M; Breil, M; Ihli, M; Messelken, M; Rauch, S; Schewe, J-C

    2014-03-01

    In Germany 100,000-160,000 people suffer from out-of-hospital cardiac arrest (OHCA) annually. The incidence of cardiopulmonary resuscitation (CPR) after OHCA varies between emergency ambulance services but is in the range of 30-90 CPR attempts per 100,000 inhabitants per year. Basic life support (BLS) involving chest compressions and ventilation is the key measure of resuscitation. Rapid initiation and quality of BLS are the most critical factors for CPR success. Even healthcare professionals are not always able to ensure the quality of CPR measures. Consequently in recent years mechanical resuscitation devices have been developed to optimize chest compression and the resulting circulation. In this article the mechanical resuscitation devices currently available in Germany are discussed and evaluated scientifically in context with available literature. The ANIMAX CPR device should not be used outside controlled trials as no clinical results have so far been published. The same applies to the new device Corpuls CPR which will be available on the market in early 2014. Based on the current published data a general recommendation for the routine use of LUCAS™ and AutoPulse® CPR cannot be given. The preliminary data of the CIRC trial and the published data of the LINC trial revealed that mechanical CPR is apparently equivalent to good manual CPR. For the final assessment further publications of large randomized studies must be analyzed (e.g. the CIRC and PaRAMeDIC trials). However, case control studies, case series and small studies have already shown that in special situations and in some cases patients will benefit from the automatic mechanical resuscitation devices (LUCAS™, AutoPulse®). This applies especially to emergency services where standard CPR quality is far below average and for patients who require prolonged CPR under difficult circumstances. This might be true in cases of resuscitation due to hypothermia, intoxication and pulmonary embolism as well as

  19. Compressive beamforming.

    PubMed

    Xenaki, Angeliki; Gerstoft, Peter; Mosegaard, Klaus

    2014-07-01

    Sound source localization with sensor arrays involves the estimation of the direction-of-arrival (DOA) from a limited number of observations. Compressive sensing (CS) solves such underdetermined problems achieving sparsity, thus improved resolution, and can be solved efficiently with convex optimization. The DOA estimation problem is formulated in the CS framework and it is shown that CS has superior performance compared to traditional DOA estimation methods especially under challenging scenarios such as coherent arrivals and single-snapshot data. An offset and resolution analysis is performed to indicate the limitations of CS. It is shown that the limitations are related to the beampattern, thus can be predicted. The high-resolution capabilities and the robustness of CS are demonstrated on experimental array data from ocean acoustic measurements for source tracking with single-snapshot data. PMID:24993212

  20. Mechanical methods for thrombosis prophylaxis.

    PubMed

    Caprini, Joseph A

    2010-12-01

    Prevention of venous thromboembolism (VTE) remains the number one preventable cause of death in hospitalized patients. The pathogenesis of thrombosis involves the triad of venous stasis, dilatation of the leg veins, and changes in coagulability of the blood. These changes can be modified by the use of intermittent pneumatic compression devices (IPC) and, to a much lesser extent, by graduated compression hose (GCS). Studies have shown the effectiveness of GCS in preventing deep vein thrombosis (DVT) compared to placebo, but there is no evidence that they reduce the incidence of pulmonary emboli (PE). No venographic data are available regarding the efficacy of GCS; however, IPC have shown excellent efficacy in several venographic studies over the past 25 years. Mechanical methods are important to use in situations where the risk of bleeding exists, thereby making the use of anticoagulants hazardous. One of the key uses for mechanical methods is in combination with anticoagulants in patients at the highest risk of developing VTE. Chest consensus guidelines assigns a 2A recommendation for the use of combination prophylaxis in the highest risk patients. Unfortunately, studies to show which type of leg compression device is optimal for DVT prevention are not available, so individual preference, ease of use, and company support are the determining factors at the present time. Finally, compliance using these devices is a major problem, and until systems have been developed to easily monitor and ensure compliance, these methods will enjoy only limited use. PMID:19850588

  1. Algorithm of chest wall keloid treatment.

    PubMed

    Long, Xiao; Zhang, Mingzi; Wang, Yang; Zhao, Ru; Wang, Youbin; Wang, Xiaojun

    2016-08-01

    Keloids are common in the Asian population. Multiple or huge keloids can appear on the chest wall because of its tendency to develop acne, sebaceous cyst, etc. It is difficult to find an ideal treatment for keloids in this area due to the limit of local soft tissues and higher recurrence rate. This study aims at establishing an individualized protocol that could be easily applied according to the size and number of chest wall keloids.A total of 445 patients received various methods (4 protocols) of treatment in our department from September 2006 to September 2012 according to the size and number of their chest wall keloids. All of the patients received adjuvant radiotherapy in our hospital. Patient and Observer Scar Assessment Scale (POSAS) was used to assess the treatment effect by both doctors and patients. With mean follow-up time of 13 months (range: 6-18 months), 362 patients participated in the assessment of POSAS with doctors.Both the doctors and the patients themselves used POSAS to evaluate the treatment effect. The recurrence rate was 0.83%. There was an obvious significant difference (P < 0.001) between the before-surgery score and the after-surgery score from both doctors and patients, indicating that both doctors and patients were satisfied with the treatment effect.Our preliminary clinical result indicates that good clinical results could be achieved by choosing the proper method in this algorithm for Chinese patients with chest wall keloids. This algorithm could play a guiding role for surgeons when dealing with chest wall keloid treatment. PMID:27583896

  2. Bone suppression technique for chest radiographs

    NASA Astrophysics Data System (ADS)

    Huo, Zhimin; Xu, Fan; Zhang, Jane; Zhao, Hui; Hobbs, Susan K.; Wandtke, John C.; Sykes, Anne-Marie; Paul, Narinder; Foos, David

    2014-03-01

    High-contrast bone structures are a major noise contributor in chest radiographic images. A signal of interest in a chest radiograph could be either partially or completely obscured or "overshadowed" by the highly contrasted bone structures in its surrounding. Thus, removing the bone structures, especially the posterior rib and clavicle structures, is highly desirable to increase the visibility of soft tissue density. We developed an innovative technology that offers a solution to suppress bone structures, including posterior ribs and clavicles, on conventional and portable chest X-ray images. The bone-suppression image processing technology includes five major steps: 1) lung segmentation, 2) rib and clavicle structure detection, 3) rib and clavicle edge detection, 4) rib and clavicle profile estimation, and 5) suppression based on the estimated profiles. The bone-suppression software outputs an image with both the rib and clavicle structures suppressed. The rib suppression performance was evaluated on 491 images. On average, 83.06% (±6.59%) of the rib structures on a standard chest image were suppressed based on the comparison of computer-identified rib areas against hand-drawn rib areas, which is equivalent to about an average of one rib that is still visible on a rib-suppressed image based on a visual assessment. Reader studies were performed to evaluate reader performance in detecting lung nodules and pneumothoraces with and without a bone-suppression companion view. Results from reader studies indicated that the bone-suppression technology significantly improved radiologists' performance in the detection of CT-confirmed possible nodules and pneumothoraces on chest radiographs. The results also showed that radiologists were more confident in making diagnoses regarding the presence or absence of an abnormality after rib-suppressed companion views were presented

  3. Algorithm of chest wall keloid treatment

    PubMed Central

    Long, Xiao; Zhang, Mingzi; Wang, Yang; Zhao, Ru; Wang, Youbin; Wang, Xiaojun

    2016-01-01

    Abstract Keloids are common in the Asian population. Multiple or huge keloids can appear on the chest wall because of its tendency to develop acne, sebaceous cyst, etc. It is difficult to find an ideal treatment for keloids in this area due to the limit of local soft tissues and higher recurrence rate. This study aims at establishing an individualized protocol that could be easily applied according to the size and number of chest wall keloids. A total of 445 patients received various methods (4 protocols) of treatment in our department from September 2006 to September 2012 according to the size and number of their chest wall keloids. All of the patients received adjuvant radiotherapy in our hospital. Patient and Observer Scar Assessment Scale (POSAS) was used to assess the treatment effect by both doctors and patients. With mean follow-up time of 13 months (range: 6–18 months), 362 patients participated in the assessment of POSAS with doctors. Both the doctors and the patients themselves used POSAS to evaluate the treatment effect. The recurrence rate was 0.83%. There was an obvious significant difference (P < 0.001) between the before-surgery score and the after-surgery score from both doctors and patients, indicating that both doctors and patients were satisfied with the treatment effect. Our preliminary clinical result indicates that good clinical results could be achieved by choosing the proper method in this algorithm for Chinese patients with chest wall keloids. This algorithm could play a guiding role for surgeons when dealing with chest wall keloid treatment. PMID:27583896

  4. [Chest Wall Reconstruction Using Titanium Plates Sandwiched Between Sheets after Resection of Chest Wall Chondrosarcoma].

    PubMed

    Endoh, Makoto; Oizumi, Hiroyuki; Kato, Hirohisa; Suzuki, Jun; Watarai, Hikaru; Hamada, Akira; Suzuki, Katsuyuki; Takahashi, Ai; Nakahashi, Kenta; Sugawara, Masato; Tsuchiya, Takashi; Sadahiro, Mitsuaki

    2016-07-01

    Extensive chest wall resection carries the risk of difficult reconstruction and surgical complications. We report our experience on chest wall reconstruction using titanium plates for a wide thoracic defect after tumor resection. A 74-year-old man was diagnosed with chondrosarcoma of the 6th rib on the right. He needed extensive chest wall resection because of skip lesions on 4th rib noted on operative inspection, leaving a defect measuring 33 × 20 cm. Reconstruction using 5 transverse titanium plates sandwiched between an expanded polytetrafluoroethylene patch and a polypropylene mesh sheet stabilized the chest wall. This reconstruction allowed successful separation from ventilatory support after operation. The postoperative course was uneventful, and he was discharged on postoperative day 20. The advantages of this form of reconstruction over conventional prostheses are rigidity, and stability and usability. PMID:27365062

  5. Psoriasis, guttate on the arms and chest (image)

    MedlinePlus

    ... guttate (drop-shaped) psoriasis on the arms and chest. Guttate psoriasis is a rare form of psoriasis. ... streptococcal infection, appears rapidly and affects the face, chest, and nearest limbs. The patches are small and ...

  6. Coughing Wheezing Shortness of Breath Tightness in Chest

    MedlinePlus

    ... Issues Coughing Wheezing Shortness of Breath Tightness in Chest Past Issues / Fall 2006 Table of Contents For ... short of breath or feel tightness in your chest, you might have asthma. If you do, you ...

  7. 42 CFR 37.50 - Interpreting and classifying chest roentgenograms.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Interpreting and classifying chest roentgenograms... MEDICAL CARE AND EXAMINATIONS SPECIFICATIONS FOR MEDICAL EXAMINATIONS OF UNDERGROUND COAL MINERS Chest Roentgenographic Examinations Specifications for Interpretation, Classification, and Submission of...

  8. 42 CFR 37.50 - Interpreting and classifying chest roentgenograms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Interpreting and classifying chest roentgenograms... MEDICAL CARE AND EXAMINATIONS SPECIFICATIONS FOR MEDICAL EXAMINATIONS OF UNDERGROUND COAL MINERS Chest Roentgenographic Examinations Specifications for Interpretation, Classification, and Submission of...

  9. 42 CFR 37.50 - Interpreting and classifying chest roentgenograms.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Interpreting and classifying chest roentgenograms... MEDICAL CARE AND EXAMINATIONS SPECIFICATIONS FOR MEDICAL EXAMINATIONS OF UNDERGROUND COAL MINERS Chest Roentgenographic Examinations Specifications for Interpretation, Classification, and Submission of...

  10. Coughing Wheezing Shortness of Breath Tightness in Chest

    MedlinePlus

    ... Current Issue Past Issues Coughing Wheezing Shortness of Breath Tightness in Chest Past Issues / Fall 2006 Table ... you cough a lot, wheeze, are short of breath or feel tightness in your chest, you might ...

  11. 30 CFR 77.412 - Compressed air systems.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Compressed air systems. 77.412 Section 77.412... for Mechanical Equipment § 77.412 Compressed air systems. (a) Compressors and compressed-air receivers... involving the pressure system of compressors, receivers, or compressed-air-powered equipment shall not...

  12. Tube thoracostomy; chest tube implantation and follow up

    PubMed Central

    Kuhajda, Ivan; Zarogoulidis, Konstantinos; Kougioumtzi, Ioanna; Huang, Haidong; Li, Qiang; Dryllis, Georgios; Kioumis, Ioannis; Pitsiou, Georgia; Machairiotis, Nikolaos; Katsikogiannis, Nikolaos; Papaiwannou, Antonis; Lampaki, Sofia; Papaiwannou, Antonis; Zaric, Bojan; Branislav, Perin; Porpodis, Konstantinos

    2014-01-01

    Pneumothorax is an urgent medical situation that requires urgent treatment. We can divide this entity based on the etiology to primary and secondary. Chest tube implantation can be performed either in the upper chest wall or lower. Both thoracic surgeons and pulmonary physicians can place a chest tube with minimal invasive techniques. In our current work, we will demonstrate chest tube implantation to locations, methodology and tools. PMID:25337405

  13. Compression-bending of multi-component semi-rigid columns in response to axial loads and conjugate reciprocal extension-prediction of mechanical behaviours and implications for structural design.

    PubMed

    Lau, Ernest W

    2013-01-01

    The mathematical modelling of column buckling or beam bending under an axial or transverse load is well established. However, the existent models generally assume a high degree of symmetry in the structure of the column and minor longitudinal and transverse displacements. The situation when the column is made of several components with different mechanical properties asymmetrically distributed in the transverse section, semi-rigid, and subjected to multiple axial loads with significant longitudinal and transverse displacements through compression and bending has not been well characterised. A more comprehensive theoretical model allowing for these possibilities and assuming a circular arc contour for the bend is developed, and used to establish the bending axes, balance between compression and bending, and equivalent stiffness of the column. In certain situations, such as with pull cable catheters commonly used for minimally invasive surgical procedures, the compression loads are applied via cables running through channels inside a semi-rigid column. The model predicts the mathematical relationships between the radius of curvature of the bend and the tension in and normal force exerted by such cables. Conjugate extension with reciprocal compression-bending is a special structural arrangement for a semi-rigid column such that extension of one segment is linked to compression-bending of another by inextensible cables running between them. Leads are cords containing insulated electrical conductor coil and cables between the heart muscle and cardiac implantable electronic devices. Leads can behave like pull cable catheters through differential component pulling, providing a possible mechanism for inside-out abrasion and conductor cable externalisation. Certain design features may predispose to this mode of structural failure. PMID:23127643

  14. Traumatic chest injury in children: A single thoracic surgeon's experience in two Nigerian tertiary hospitals

    PubMed Central

    Okonta, Kelechi Emmanuel

    2015-01-01

    Background: This study was to determine the extent and outcome of childhood chest injury in Nigeria, and to compare results with that of other literatures. Patients and Methods: A Prospective study of all children under 18 years of age with chest trauma in two tertiary hospitals in Southern Nigeria from January 2012 to December 2014 was reviewed. The aetiology, type, associated injury, mechanism, treatment and outcome were evaluated. The patients were followed up in the clinic. The data were analysed using SPSS version 20.0 with a significant P < 0.05. Results: Thirty-one patients (12.1%) under 18 years of age of 256 chest trauma patients were managed in the thoracic units. The mean age was 9.78 ± 6.77 years and 27 (87.1%) were male. The aetiology in 13 was from falls, 10 from automobile crashes, 3 from gunshots, 4 from stabbing and 1 from abuse. The highest peak of chest injury was on Saturday of the week and April of the year. The pleural collections are as follows: 15 (71.4%) was haemothorax, 4 (19.1%) pneumothorax, 2 (9.5%) haemopneumothorax and 18 patients had lung contusion in combination or alone with the pleural collections. Seven patients who presented >12-h versus 2 who presented <12-h and 6 of children between 0 and 9 years versus 3 at 10-18 years of age had empyema thoracis (P value not significant). One death was recorded. Conclusion: Chest trauma in children is still not common, and blunt chest injury from falls and automobile accidents are more common than penetrating chest injury. Treatment with tube thoracostomy is the major management modality with empyema thoracis as the most common complication. PMID:26612123

  15. 20 CFR 718.102 - Chest roentgenograms (X-rays).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Chest roentgenograms (X-rays). 718.102... roentgenograms (X-rays). (a) A chest roentgenogram (X-ray) shall be of suitable quality for proper classification of pneumoconiosis and shall conform to the standards for administration and interpretation of chest...

  16. 20 CFR 718.102 - Chest roentgenograms (X-rays).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 4 2013-04-01 2013-04-01 false Chest roentgenograms (X-rays). 718.102... roentgenograms (X-rays). (a) A chest roentgenogram (X-ray) shall be of suitable quality for proper classification of pneumoconiosis and shall conform to the standards for administration and interpretation of chest...

  17. 20 CFR 718.102 - Chest roentgenograms (X-rays).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 4 2014-04-01 2014-04-01 false Chest roentgenograms (X-rays). 718.102... roentgenograms (X-rays). (a) A chest roentgenogram (X-ray) shall be of suitable quality for proper classification of pneumoconiosis and shall conform to the standards for administration and interpretation of chest...

  18. 20 CFR 718.102 - Chest roentgenograms (X-rays).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false Chest roentgenograms (X-rays). 718.102... roentgenograms (X-rays). (a) A chest roentgenogram (X-ray) shall be of suitable quality for proper classification of pneumoconiosis and shall conform to the standards for administration and interpretation of chest...

  19. 20 CFR 718.102 - Chest roentgenograms (X-rays).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 4 2012-04-01 2012-04-01 false Chest roentgenograms (X-rays). 718.102... roentgenograms (X-rays). (a) A chest roentgenogram (X-ray) shall be of suitable quality for proper classification of pneumoconiosis and shall conform to the standards for administration and interpretation of chest...

  20. 46 CFR 108.651 - Portable magazine chests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Portable magazine chests. 108.651 Section 108.651... AND EQUIPMENT Equipment Markings and Instructions § 108.651 Portable magazine chests. Each portable magazine chest must be marked: “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS AND FIRE AWAY” in letters...

  1. 42 CFR 37.3 - Chest radiographs required for miners.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Chest radiographs required for miners. 37.3 Section... EXAMINATIONS SPECIFICATIONS FOR MEDICAL EXAMINATIONS OF COAL MINERS Chest Radiographic Examinations § 37.3 Chest radiographs required for miners. (a) Voluntary examinations. Every operator must provide to...

  2. 46 CFR 108.651 - Portable magazine chests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Portable magazine chests. 108.651 Section 108.651... AND EQUIPMENT Equipment Markings and Instructions § 108.651 Portable magazine chests. Each portable magazine chest must be marked: “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS AND FIRE AWAY” in letters...

  3. 46 CFR 78.47-70 - Portable magazine chests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 3 2011-10-01 2011-10-01 false Portable magazine chests. 78.47-70 Section 78.47-70... Fire and Emergency Equipment, Etc. § 78.47-70 Portable magazine chests. (a) Portable magazine chest shall be marked in letters of at least 3 inches high “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS...

  4. 46 CFR 97.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Portable magazine chests. 97.37-47 Section 97.37-47... OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  5. 46 CFR 169.743 - Portable magazine chests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Portable magazine chests. 169.743 Section 169.743... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.743 Portable magazine chests. Portable magazine chests must be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  6. 46 CFR 78.47-70 - Portable magazine chests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 3 2012-10-01 2012-10-01 false Portable magazine chests. 78.47-70 Section 78.47-70... Fire and Emergency Equipment, Etc. § 78.47-70 Portable magazine chests. (a) Portable magazine chest shall be marked in letters of at least 3 inches high “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS...

  7. 46 CFR 108.651 - Portable magazine chests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Portable magazine chests. 108.651 Section 108.651... AND EQUIPMENT Equipment Markings and Instructions § 108.651 Portable magazine chests. Each portable magazine chest must be marked: “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS AND FIRE AWAY” in letters...

  8. 46 CFR 78.47-70 - Portable magazine chests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 3 2014-10-01 2014-10-01 false Portable magazine chests. 78.47-70 Section 78.47-70... Fire and Emergency Equipment, Etc. § 78.47-70 Portable magazine chests. (a) Portable magazine chest shall be marked in letters of at least 3 inches high “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS...

  9. 46 CFR 169.743 - Portable magazine chests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Portable magazine chests. 169.743 Section 169.743... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.743 Portable magazine chests. Portable magazine chests must be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  10. 42 CFR 37.3 - Chest roentgenograms required for miners.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Chest roentgenograms required for miners. 37.3... EXAMINATIONS SPECIFICATIONS FOR MEDICAL EXAMINATIONS OF UNDERGROUND COAL MINERS Chest Roentgenographic Examinations § 37.3 Chest roentgenograms required for miners. (a) Voluntary examinations. Every operator...

  11. 42 CFR 37.3 - Chest roentgenograms required for miners.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Chest roentgenograms required for miners. 37.3... EXAMINATIONS SPECIFICATIONS FOR MEDICAL EXAMINATIONS OF UNDERGROUND COAL MINERS Chest Roentgenographic Examinations § 37.3 Chest roentgenograms required for miners. (a) Voluntary examinations. Every operator...

  12. 46 CFR 169.743 - Portable magazine chests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Portable magazine chests. 169.743 Section 169.743... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.743 Portable magazine chests. Portable magazine chests must be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  13. 46 CFR 108.651 - Portable magazine chests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Portable magazine chests. 108.651 Section 108.651... AND EQUIPMENT Equipment Markings and Instructions § 108.651 Portable magazine chests. Each portable magazine chest must be marked: “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS AND FIRE AWAY” in letters...

  14. 46 CFR 97.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Portable magazine chests. 97.37-47 Section 97.37-47... OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  15. 46 CFR 78.47-70 - Portable magazine chests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 3 2013-10-01 2013-10-01 false Portable magazine chests. 78.47-70 Section 78.47-70... Fire and Emergency Equipment, Etc. § 78.47-70 Portable magazine chests. (a) Portable magazine chest shall be marked in letters of at least 3 inches high “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS...

  16. 42 CFR 37.3 - Chest roentgenograms required for miners.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Chest roentgenograms required for miners. 37.3... EXAMINATIONS SPECIFICATIONS FOR MEDICAL EXAMINATIONS OF UNDERGROUND COAL MINERS Chest Roentgenographic Examinations § 37.3 Chest roentgenograms required for miners. (a) Voluntary examinations. Every operator...

  17. 46 CFR 169.743 - Portable magazine chests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Portable magazine chests. 169.743 Section 169.743... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.743 Portable magazine chests. Portable magazine chests must be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  18. 46 CFR 97.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Portable magazine chests. 97.37-47 Section 97.37-47... OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  19. 46 CFR 97.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Portable magazine chests. 97.37-47 Section 97.37-47... OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  20. 46 CFR 108.651 - Portable magazine chests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Portable magazine chests. 108.651 Section 108.651... AND EQUIPMENT Equipment Markings and Instructions § 108.651 Portable magazine chests. Each portable magazine chest must be marked: “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS AND FIRE AWAY” in letters...

  1. 46 CFR 169.743 - Portable magazine chests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Portable magazine chests. 169.743 Section 169.743... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.743 Portable magazine chests. Portable magazine chests must be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  2. 46 CFR 78.47-70 - Portable magazine chests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Portable magazine chests. 78.47-70 Section 78.47-70... Fire and Emergency Equipment, Etc. § 78.47-70 Portable magazine chests. (a) Portable magazine chest shall be marked in letters of at least 3 inches high “PORTABLE MAGAZINE CHEST—FLAMMABLE—KEEP LIGHTS...

  3. 42 CFR 37.3 - Chest radiographs required for miners.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Chest radiographs required for miners. 37.3 Section... EXAMINATIONS SPECIFICATIONS FOR MEDICAL EXAMINATIONS OF UNDERGROUND COAL MINERS Chest Roentgenographic Examinations § 37.3 Chest radiographs required for miners. (a) Voluntary examinations. Every operator...

  4. 46 CFR 97.37-47 - Portable magazine chests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Portable magazine chests. 97.37-47 Section 97.37-47... OPERATIONS Markings for Fire and Emergency Equipment, Etc. § 97.37-47 Portable magazine chests. (a) Portable magazine chests shall be marked in letters at least 3 inches high: “PORTABLE MAGAZINE...

  5. Extreme compression for extreme conditions: pilot study to identify optimal compression of CT images using MPEG-4 video compression.

    PubMed

    Peterson, P Gabriel; Pak, Sung K; Nguyen, Binh; Jacobs, Genevieve; Folio, Les

    2012-12-01

    This study aims to evaluate the utility of compressed computed tomography (CT) studies (to expedite transmission) using Motion Pictures Experts Group, Layer 4 (MPEG-4) movie formatting in combat hospitals when guiding major treatment regimens. This retrospective analysis was approved by Walter Reed Army Medical Center institutional review board with a waiver for the informed consent requirement. Twenty-five CT chest, abdomen, and pelvis exams were converted from Digital Imaging and Communications in Medicine to MPEG-4 movie format at various compression ratios. Three board-certified radiologists reviewed various levels of compression on emergent CT findings on 25 combat casualties and compared with the interpretation of the original series. A Universal Trauma Window was selected at -200 HU level and 1,500 HU width, then compressed at three lossy levels. Sensitivities and specificities for each reviewer were calculated along with 95 % confidence intervals using the method of general estimating equations. The compression ratios compared were 171:1, 86:1, and 41:1 with combined sensitivities of 90 % (95 % confidence interval, 79-95), 94 % (87-97), and 100 % (93-100), respectively. Combined specificities were 100 % (85-100), 100 % (85-100), and 96 % (78-99), respectively. The introduction of CT in combat hospitals with increasing detectors and image data in recent military operations has increased the need for effective teleradiology; mandating compression technology. Image compression is currently used to transmit images from combat hospital to tertiary care centers with subspecialists and our study demonstrates MPEG-4 technology as a reasonable means of achieving such compression. PMID:22722754

  6. Compression mechanism of subpicosecond pulses by malachite green dye in passively mode-locked rhodamine 6G/DODCI CW dye lasers

    SciTech Connect

    Watanabe, A.; Hara, M.; Kobayashi, H.; Takemura, H.; Tanaka, S.

    1983-04-01

    The pulse width compression effect of a malachite green (MG) dye upon subpicosecond pulses has been experimentally investigated in a CW passively mode-locked rhodamine 6G/DODCI dye laser. The pulse width reduces as MG concentration increases, and reaches 0.34 ps at 1.5 X 10/sup -6/ M. By adding the MG dye, good mode locking is achieved in a rather wide pumping-power range. A computer simulation of pulse growth has also been carried out by using simple rate equations, in which the fast-recovery component of loss due to the MG dye is taken into account. The simulated results can explain some experimental results qualitatively such as pulse width compression and pumping-power restriction. The pulse width compression results essentially from the fast recovery of cavity loss caused by the MG dye.

  7. Cardiac output during cardiopulmonary resuscitation at various compression rates and durations.

    PubMed

    Fitzgerald, K R; Babbs, C F; Frissora, H A; Davis, R W; Silver, D I

    1981-09-01

    Cardiac output during cardiopulmonary resuscitation (CPR) was measured by a modified indicator-dilution technique in 20 anesthetized dogs (6-12 kg), during repeated 1- to 2-min episodes of electrically induced ventricular fibrillation, by a mechanical chest compressor and ventilator. With compression rates from 20 to 140/min and compression durations (duty cycles) from 10 to 90% of cycle time, cardiac output (CO) was predicted by the equation: CO = CR . SVmax . [DC/(k1 . CR + DC)] . [(1 -- DC)/k2 . CR + 1 - DC)], where CR is compression rate, DC is duty cycle, SVmax (19 ml) is the effective capacity of the pumping chamber, and k1 (0.00207 min) and k2 (0.00707 min) are ejection and filling constants. This expression predicts maximal CO for DC = 0.40 and cR = 126/min and 90-100% of maximal CO for 0.3 less than DC less than 0.5 and 70 less than CR less than 150/min. Such mathematical analysis may prove useful in the optimization of CPR. PMID:7282953

  8. Chest pain caused by tracheostomy tube malposition: the importance of choosing the right tube.

    PubMed

    Inchingolo, R; Smargiassi, A; Bello, G; Pennisi, M A; Chiappini, F; Pirronti, T; Valente, S

    2011-02-01

    We describe a case of chest pain caused by tracheostomy tube malposition in a 65-year old woman with chronic respiratory failure due to chronic obstructive pulmonary disease. This report highlights the importance of the correct choice of tracheostomy tube devices for mechanically ventilated and/or spontaneously breathing patients. PMID:21283068

  9. Prospective study of anterior chest wall involvement in ankylosing spondylitis and psoriatic arthritis.

    PubMed

    Fournié, B; Boutes, A; Dromer, C; Sixou, L; Le Guennec, P; Granel, J; Railhac, J J

    1997-01-01

    A prospective study of anterior chest wall involvement was conducted in 50 ankylosing spondylitis patients and 50 psoriatic arthritis patients in the absence of palmoplantar pustulosis. All patients underwent a physical examination, tomograms, and a radionuclide bone scan. Magnetic resonance imaging with gadolinium was done in some cases. Half the patients in both groups had anterior chest wall involvement. Enthesitis was the mechanism of the lesions. The manubriosternal symphysis and sternocostoclavicular joints were the most common sites of involvement, although other entheses in the region were affected in some patients. PMID:9051856

  10. Airway hyperresponsiveness with chest strapping: A matter of heterogeneity or reduced lung volume?

    PubMed

    Pellegrino, Riccardo; Pompilio, Pasquale P; Bruni, Giulia Innocenti; Scano, Giorgio; Crimi, Claudia; Biasco, Luigi; Coletta, Giuseppe; Cornara, Giuseppe; Torchio, Roberto; Brusasco, Vito; Dellacà, Raffaele L

    2009-03-31

    Chest wall strapping has been recently shown to be associated with an increase in airway responsiveness to methacholine. To investigate whether this is the result of the decreased lung volume or an increased heterogeneity due to chest wall distortion, ten healthy volunteers underwent a methacholine challenge at control conditions and after selective strapping of the rib cage, the abdomen or the whole chest wall resulting in similar decrements of functional residual capacity and total lung capacity but causing different distribution of the bronchoconstrictor. Methacholine during strapping reduced forced expiratory flow, dynamic compliance, and reactance at 5Hz and increased pulmonary resistance and respiratory resistance at 5Hz that were significantly greater than at control and associated with a blunted bronchodilator effect of the deep breath. However, no significant differences were observed between selective and total chest wall strapping, suggesting that the major mechanism for increasing airway responsiveness with chest wall strapping is the breathing at low lung volume rather than regional heterogeneities. PMID:19429518

  11. [New aspects of compression therapy].

    PubMed

    Partsch, Bernhard; Partsch, Hugo

    2016-06-01

    In this review article the mechanisms of action of compression therapy are summarized and a survey of materials is presented together with some practical advice how and when these different devices should be applied. Some new experimental findings regarding the optimal dosage (= compression pressure) concerning an improvement of venous hemodynamics and a reduction of oedema are discussed. It is shown, that stiff, non-yielding material applied with adequate pressure provides hemodynamically superior effects compared to elastic material and that relatively low pressures reduce oedema. Compression over the calf is more important to increase the calf pump function compared to graduated compression. In patients with mixed, arterial-venous ulcers and an ABPI over 0.6 inelastic bandages not exceeding a sub-bandage pressure of 40 mmHg may increase the arterial flow and improve venous pumping function. PMID:27259340

  12. [NECROTIZING FASCIITIS OF THE CHEST WALL].

    PubMed

    Farah, Raymond; Asla, Husam

    2016-04-01

    Necrotizing fasciitis (NF) is a bacterial dermo-hypodermitis affecting the soft tissue and muscular fascia. It is an uncommon and severe infection caused by microorganisms called 'flesh eating bacteria', mainly represented by group A beta-haemolytic streptococcus. NF remains a life-threatening condition associated with a high mortality rate. Its location on the chest wall is extremely rare. The few reported cases are subsequent to thoracic drainage, lung surgery or esophageal resection. This is a case report of an 80-year old female with comorbidity of heart disease, a past history of coronary artery by-pass and diabetes. She was admitted to the emergency room with acute NF of the chest and shortly after diagnosis, the patient died. Due to the fast decline observed in this disease, we would like to emphasize the importance of early recognition and diagnosis. PMID:27323534

  13. Myocardial contusion following nonfatal blunt chest trauma

    SciTech Connect

    Kumar, S.A.; Puri, V.K.; Mittal, V.K.; Cortez, J.

    1983-04-01

    Currently available diagnostic techniques for myocardial contusion following blunt chest trauma were evaluated. We investigated 30 patients prospectively over a period of 1 year for the presence of myocardial contusion. Among the 30 patients, eight were found to have myocardial contusion on the basis of abnormal electrocardiograms, elevated creatine phosphokinase MB fraction (CPK-MB), and positive myocardial scan. Myocardial scan was positive in seven of eight patients (87.5%). CPK-MB fraction was elevated in four of eight patients (50%). Definitive electrocardiographic changes were seen in only two of eight patients (25%). It appears that myocardial scan using technetium pyrophosphate and CPK-MB fraction determinations are the most reliable aids in diagnosis of myocardial contusion following blunt chest trauma.

  14. Advances in chest drain management in thoracic disease

    PubMed Central

    George, Robert S.

    2016-01-01

    An adequate chest drainage system aims to drain fluid and air and restore the negative pleural pressure facilitating lung expansion. In thoracic surgery the post-operative use of the conventional underwater seal chest drainage system fulfills these requirements, however they allow great variability amongst practices. In addition they do not offer accurate data and they are often inconvenient to both patients and hospital staff. This article aims to simplify the myths surrounding the management of chest drains following chest surgery, review current experience and explore the advantages of modern digital chest drain systems and address their disease-specific use. PMID:26941971

  15. [Chest wall tuberculosis: report of 3 cases].

    PubMed

    Zidane, A; Bakzaza, O; Afandi, O; Baiz, Y; Chafik, A

    2015-10-01

    Despite the dramatic decline in the incidence of tuberculosis during the last decades, the disease remains a significant public health problem especially in developing countries. Chest wall tuberculosis is a very rare location. Clinically, it can present as a pyogenic abscess or soft tumor, making diagnosis difficult, particularly in the absence of warning signs. Optimal therapeutic management is controversial. Medical treatment alone in often insufficient and must be associated with a surgical excision or debridement. PMID:25725600

  16. Exercises in chest X-ray diagnosis

    SciTech Connect

    Elliott, J.A.; Cowan, M.D.

    1986-01-01

    In the fifty exercises which form the first part of the book, radiographs are combined with a group of questions designed to test the readers clinical and radiological knowledge. The exercises cover all the common and many of the rarer cardiothoracic disorders which are revealed on the chest x-ray. Increasingly, computed tomography is used in the differential diagnosis of thoracic problems, and several examples have been included.

  17. Reconstruction of full thickness chest wall defects.

    PubMed Central

    Morgan, R F; Edgerton, M T; Wanebo, H J; Daniel, T M; Spotnitz, W D; Kron, I L

    1988-01-01

    Over the last 5 years, 14 patients were treated by wide en bloc resection of chest wall tumors with primary reconstruction. There were nine females and five male patients with an age range of 31-77 years. All patients had a skeletal resection of the chest wall. An average of 3.9 ribs were resected in the patients treated. In three patients a partial sternectomy was carried out in conjunction with the rib resections. Chest wall skeletal defects were reconstructed with Prolene mesh, which was placed under tension. Soft tissue reconstruction utilized selected portions of the latissimus dorsi musculocutaneous territory with fasciocutaneous extensions beyond the muscle itself. Primary healing was obtained in all patients and secondary procedures were not required. The average hospitalization was 23 days. All patients survived the resection and reconstruction and were alive 30 days after operation. In selected patients the preservation of a portion of the innervated muscle in situ or the transfer of the muscle with the preservation of its resting length has maintained the majority of the muscle function. Images Fig. 3A. Fig. 3C. Fig. 3D. Fig. 4A. Fig. 4C. Fig. 4D. Fig. 4E. Fig. 5A. Fig. 5B. Fig. 5D. Fig. 6A. Fig. 6C. Fig. 6D. Fig. 6E. Fig. 6F. Fig. 6G. Fig. 6H. PMID:3389939

  18. Chest pain: coronary CT in the ER.

    PubMed

    Maffei, Erica; Seitun, Sara; Guaricci, Andrea I; Cademartiri, Filippo

    2016-01-01

    Cardiac CT has developed into a robust clinical tool during the past 15 years. Of the fields in which the potential of cardiac CT has raised more interest is chest pain in acute settings. In fact, the possibility to exclude with high reliability obstructive coronary artery disease (CAD) in patients at low-to-intermediate risk is of great interest both from the clinical standpoint and from the management standpoint. Several other modalities, with or without imaging, have been used during the past decades in the settings of new onset chest pain or in acute chest pain for both diagnostic and prognostic assessment of CAD. Each one has advantages and disadvantages. Most imaging modalities also focus on inducible ischaemia to guide referral to invasive coronary angiography. The advent of cardiac CT has introduced a new practice diagnostic paradigm, being the most accurate non-invasive method for identification and exclusion of CAD. Furthermore, the detection of subclinical CAD and plaque imaging offer the opportunity to improve risk stratification. Moreover, recent advances of the latest generation CT scanners allow combining both anatomical and functional imaging by stress myocardial perfusion. The role of cardiac CT in acute settings is already important and will become progressively more important in the coming years. PMID:26866681

  19. Surface chest motion decomposition for cardiovascular monitoring.

    PubMed

    Shafiq, Ghufran; Veluvolu, Kalyana C

    2014-01-01

    Surface chest motion can be easily monitored with a wide variety of sensors such as pressure belts, fiber Bragg gratings and inertial sensors, etc. The current applications of these sensors are mainly restricted to respiratory motion monitoring/analysis due to the technical challenges involved in separation of the cardiac motion from the dominant respiratory motion. The contribution of heart to the surface chest motion is relatively very small as compared to the respiratory motion. Further, the heart motion spectrally overlaps with the respiratory harmonics and their separation becomes even more challenging. In this paper, we approach this source separation problem with independent component analysis (ICA) framework. ICA with reference (ICA-R) yields only desired component with improved separation, but the method is highly sensitive to the reference generation. Several reference generation approaches are developed to solve the problem. Experimental validation of these proposed approaches is performed with chest displacement data and ECG obtained from healthy subjects under normal breathing and post-exercise conditions. The extracted component morphologically matches well with the collected ECG. Results show that the proposed methods perform better than conventional band pass filtering. PMID:24865183

  20. Chest wall tumour following iodized talc pleurodesis

    PubMed Central

    Jackson, John W.; Bennett, M. H.

    1973-01-01

    Jackson, J. W., and Bennett, M. H. (1973).Thorax, 28, 788-793. Chest wall tumour following iodized talc pleurodesis. A man of 37 had an iodized talc pleurodesis carried out for recurrent spontaneous pneumothorax. There was no history of industrial exposure to asbestos. Two years later he presented with pain in the right chest and radiographs at that time showed some localized pleural thickening at the site of the thoracoscopy cannulation for introduction of talc. A provisional diagnosis of talc granuloma, chemical abscess or tumour was made and exploratory thoracotomy revealed a tumour involving the chest wall, lung, and pleura which, on histological examination, showed adenocarcinoma of varying degrees of differentiation and in some parts also presenting a more squamoid appearance. Numerous doubly refractile talc particles were intimately associated with the tumour and fibrous tissue. Shortly after excision the patient developed evidence of systemic dissemination of the disease and died four months later. The possibility of this tumour being induced by the talc is discussed. A brief review is made of the various forms of talc used in surgery over the past 40 years and attention is drawn to the significance of the proportion of asbestos mineral which is present in talc as mined in various parts of the world. We do not consider that this is a case of mesothelioma of the pleura. Images PMID:4787992