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A comprehensive review is given of the theory and properties of nonrelativistic shocks in hot collisionless plasmas—in view of their possible application in astrophysics. Understanding non-relativistic collisionless shocks is an ...
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A comprehensive review is given of the theory and properties of nonrelativistic shocks in hot collisionless plasmas—in view of their possible application in astrophysics. Understanding non-relativistic collisionless shocks is an indispensable step towards a general account of collisionless astrophysical shocks of high Mach number and of their effects in dissipating flow-energy, in heating matter, in accelerating particles to high—presumably cosmic-ray—energies, and in generating detectable radiation from radio to X-rays. Non-relativistic shocks have Alfvénic Mach numbersMA √mi /me(ωpe/ωce), where mi /me is the ion-to-electron mass ratio, and ωpe, ωce are the electron plasma and cyclotron frequencies, respectively. Though high, the temperatures of such shocks are limited (in energy units) to T 收起
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Cardiogenic shock (CS) is a multifactorial disease process with high morbidity and mortality. When it occurs in a peri- or intraoperative setting, factors such as surgery, anesthesia, and post-surgical physiology can negatively af...
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Cardiogenic shock (CS) is a multifactorial disease process with high morbidity and mortality. When it occurs in a peri- or intraoperative setting, factors such as surgery, anesthesia, and post-surgical physiology can negatively affect patient outcomes. Since patient needs often escalate during CS—from medications to mechanical support to palliative care—this disease demands a multidisciplinary approach that encompasses all aspects of medical delivery. Preliminary studies have indicated that a multidisciplinary team approach to CS results in earlier diagnosis and treatment and improves patient outcomes. Here we discuss various management strategies for CS from an anesthesiology, surgery, and critical care perspective.
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Cost-effective mechanical shock indicators are widely used to warn if a package has been subjected to a shock event during distribution. Such devices are an important part of the quality control and monitoring process during the d...
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Cost-effective mechanical shock indicators are widely used to warn if a package has been subjected to a shock event during distribution. Such devices are an important part of the quality control and monitoring process during the distribution of fragile products. As the distances over which goods are transported continues to increase, so does the reliance on such devices to ensure that, should product damage occur due to excessive shocks during distribution, some evidence of the cause is available. However, there is a growing number of cases where false or misdetection has been reported producing misleading or confusing information hence loss of confidence in the data. This paper presents an experimental investigation into the actual response characteristics of three commercially available mechanical shock indicators (beam type, liquid-in-glass tube type and magnetic type). Specifically, this paper addresses the influence of shock pulse duration on the performance of shock indicators as well as evaluating the devices' repeatability across a broad range of shock pulse durations. Included in the paper are descriptions of the specially adapted test apparatus which employs a pneumatic rubber bladder to generate half-sine shock pulses of varying durations by adjusting the bladder pressure. Results from experiments show that each device is sensitive to shock magnitude as well as shock duration to varying extents. The paper makes recommendations on the use of the devices, and the findings highlight the need for establishing the shortest pulse duration experienced by any packaged product by means of drop tests before employing the devices. Copyright (C) 2017 John Wiley & Sons, Ltd.
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Laser shock processing (LSP) is an advanced material surface hardening technology that can significantly improve mechanical properties and extend service life by using the stress effect generated by laser-induced plasma shock wave...
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Laser shock processing (LSP) is an advanced material surface hardening technology that can significantly improve mechanical properties and extend service life by using the stress effect generated by laser-induced plasma shock waves, which has been increasingly applied in the processing fields of metallic materials and alloys. With the rapidly development of modern industry, many new technologies developed from LSP have emerged, which broadens the application of LSP and enriches its technical theory. In this work, the technical theory of LSP was summarized, which consists of the fundamental principle of LSP and the laser-induced plasma shock wave. The new technologies, developed from LSP, are introduced in detail from the aspect of laser shock forming (LSF), warm laser shock processing (WLSP), laser shock marking (LSM) and laser shock imprinting (LSI). The common feature of LSP and these new technologies developed from LSP is the utilization of the laser-generated stress effects rather than the laser thermal effect. LSF is utilized to modify the curvature of metal sheet through the laser-induced high dynamic loading. The material strength and the stability of residual stress and micro-structures by WLSP treatment are higher than that by LSP treatment, due to WLSP combining the advantages of LSP, dynamic strain aging (DSA) and dynamic precipitation (DP). LSM is an effective method to obtain the visualized marks on the surface of metallic materials or alloys, and its critical aspect is the preparation of the absorbing layer with a designed shape and suitable thickness. At the high strain rates induced by LSP, LSI has the ability to complete the direct imprinting over the large-scale ultrasmooth complex 3D nanostructures arrays on the surface of crystalline metals. This work has important reference value and guiding significance for researchers to further understand the LSP theory and the new technologies developed from LSP.
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A shock waveform is proposed based on the mechanical mechanism of shock generation in a structure. The parameters in the shock waveform have clear mechanical meanings about the generation and development of the shock. A shock sign...
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A shock waveform is proposed based on the mechanical mechanism of shock generation in a structure. The parameters in the shock waveform have clear mechanical meanings about the generation and development of the shock. A shock signal processing method is proposed and applied to represent a pyroshock or ballistic shock signal in both temporal and frequency domain using finite terms of the shock waveform components. It is found that the complexity of the shock and the dominant shock distance of a shock can be described quantitatively by the number of waveform components (η_(90%)) and a normalised parameter (κ), respectively. Pyroshock and mechanical shocks in different categories are analysed using the proposed shock waveform to demonstrate its importance and generality in shock representation.
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Hydraulic shock absorbers have been widely used to dissipate kinetic energy of the shocks into surrounding environment. By employing oscillatory motion to drive power generator, the shock energy can be converted into electricity f...
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Hydraulic shock absorbers have been widely used to dissipate kinetic energy of the shocks into surrounding environment. By employing oscillatory motion to drive power generator, the shock energy can be converted into electricity for harvesting. However, the frequent bidirectional oscillation of the generator can cause a large impact force. This further leads to deteriorated energy harvesting performance, moving parts fatigue, and even system failure. As such, this study introduces four check values to form a hydraulic rectifier to integrate the shock absorption and energy harvesting functionalities. The bidirectional oscillation of the shock and the vibration is converted into unidirectional rotation to drive the generator. Following the proposed concept, a prototype energy-harvesting shock absorber has been designed and fabricated. An electromechanical model has also been developed to examine the response behavior of the prototype device. The prototype performance has been characterized based on the experimental results from three test setups. Both mechanical and electrical parameters of the electromechanical model have been identified based on our cyclic loading experiments. The results have shown that the developed energy-harvesting shock absorber is capable of harvesting the energy and absorbing the shock simultaneously. In our experiments, a maximum of 248.8 W instantaneous power (a maximum of 114.1 W on average) has been captured and a maximum of 38.81% energy harvesting efficiency has been achieved via harmonic excitation with an amplitude of 8 mm and a frequency of 2 Hz, when the load resistance is tuned to 7.5 Ω.
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Clinical assessment and classification of shock is extremely difficult toconduct on critically ill patients. Rapid Ultrasound in Shock (RUSH) is an easily learned andquicklyperformed shock ultrasound protocol, it allows for rapid ...
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Clinical assessment and classification of shock is extremely difficult toconduct on critically ill patients. Rapid Ultrasound in Shock (RUSH) is an easily learned andquicklyperformed shock ultrasound protocol, it allows for rapid evaluation of reversible causesofshock and improves accurate diagnosis in undifferentiated hypotension. Objectives: to evaluate the accuracy of early RUSH protocol performed bychest physicians to predict type of shock and its guide of resuscitation in critically ill patients. Patients and Methods: Study was conducted on 68 patients with shock state in RespiratoryIntensive Care Unit (RICU) of Chest Department at Assuit University Hospital and evaluatedfor the cause of shock by performing early RUSH protocol for patients. Patients receivedall needed standard therapeutic and diagnostic interventions without delay and were followedtodocument their final clinical diagnosis. The agreement between the initial impressionprovided by RUSH and the final diagnosis was investigated by calculating the Kappaindex. Sensitivity, Specificity, positive predictive value (PPV) and negative predictivevalue(NPV) of RUSH for diagnosis of each case.
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Introduction: Although variability in vital parameters has been shown to predict outcomes, the role of change in shock index (delta SI) as a predictive tool remains unknown. Methods: The National Trauma Data Bank (2011-2012) was a...
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Introduction: Although variability in vital parameters has been shown to predict outcomes, the role of change in shock index (delta SI) as a predictive tool remains unknown. Methods: The National Trauma Data Bank (2011-2012) was abstracted for all patients aged 18 to 85 years and Injury Severity Score more than 15 with complete data. Transferred patients and patients dead on arrival were excluded. Patient demographics and injury parameters were recorded, and SI in the field, SI in the emergency department (ED), and change in SI (delta SI = ED SI-field SI) were calculated. Our outcome measure was mortality. Cox regression and Kaplan-Meier analysis was performed. Results: A total of 95,088 patients were included, and the overall mortality rate was 11.9%. Patients with a positive delta SI had a mortality rate of 13.3% compared with 9.6% mortality rate in patients who had an unchanged or negative delta SI. After controlling for confounders, a delta SI more than 0.1 was found to be associated with an increased hazard of death (hazard ratio [95% CI] = 1.36 [1.29-1.45]) and mortality (16.6% vs. 9.5%, P<0.001). Even in hemodynamically stable patients, a delta SI more than 0.1 was associated with increased hazard of death (hazard ratio [95% CI] = 1.29 [1.20-1.39]). Conclusions: Delta SI from field to hospital independently predicts higher mortality. It predicts higher mortality even in apparently hemodynamically stable patients with normal traditional vital signs and normal SI. Delta SI may serve as an adjunct to existing traditional vital signs for the identification of occult hypovolemic shock and higher risk of death in trauma patients.
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Cvijanovich N, Shanley TP, Lin R, Allen GL, Thomas NJ, Checchia P, Anas N, Freishtat RJ, Monaco M, Odoms K, Sak-thivel B, Wong HR, for the Genomics of Pediatric SIRS/Septic Shock Investigators. Validating the genomic signature of ...
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Cvijanovich N, Shanley TP, Lin R, Allen GL, Thomas NJ, Checchia P, Anas N, Freishtat RJ, Monaco M, Odoms K, Sak-thivel B, Wong HR, for the Genomics of Pediatric SIRS/Septic Shock Investigators. Validating the genomic signature of pediatric septic shock. Physiol Genomics 34: 127-134, 2008. First published May 6, 2008; doi:10.1152/physiolgenomics.00025.2008.—We previ-ously generated genome-wide expression data (microarray) from children with septic shock having the potential to lead the field into novel areas of investigation. Herein we seek to validate our data through a bioinformatic approach centered on a validation patient cohort. Forty-two children with a clinical diagnosis of septic shock and 15 normal controls served as the training data set, while 30 separate children with septic shock and 14 separate normal controls served as the test data set. Class prediction modeling using the training data set and the previously reported genome-wide expression signa-ture of pediatric septic shock correctly identified 95-100% of controls and septic shock patients in the test data set, depending on the class prediction algorithm and the gene selection method. Subjecting the test data set to an identical filtering strategy as that used for the training data set, demonstrated 75% concordance between the two gene lists. Subjecting the test data set to a purely statistical filtering strategy, with highly stringent correction for multiple comparisons, demonstrated <50% concordance with the previous gene filtering strategy. However, functional analysis of this statistics-based gene list demonstrated similar functional annotations and signaling pathways as that seen in the training data set. In particular, we validated that pediatric septic shock is characterized by large-scale repression of genes related to zinc homeostasis and lymphocyte function. These data demonstrate that the previously reported genome-wide expression signature of pediatric septic shock is applicable to a validation cohort of patients.
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