Academic literature on the topic 'Shock Pad'
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Journal articles on the topic "Shock Pad"
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Jørgensen, Uffe, and Finn Bojsen-Møller. "Shock Absorbency of Factors in the Shoe/Heel Interaction—With Special Focus on Role of the Heel Pad." Foot & Ankle 9, no. 6 (June 1989): 294–99. http://dx.doi.org/10.1177/107110078900900607.
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The heel pad acts as a shock absorber in walking and in heel-strike running. In some patients, a reduction of its shock-absorbing capacity has been connected to the development of overuse injuries. In this article, the shock absorption of the heel pad as well as external shock absorbers are studied. Individual variation and the effect of trauma and confinement on the heel pad were specifically investigated. Drop tests, imitating heel impacts, were performed on a force plate. The test specimens were cadaver heel pads (n = 10); the shoe sole component consisted of ethyl vinyl acetate (EVA) foam and Sorbothane inserts. The shock absorption was significantly greater in the heel pad than in the external shock absorbers. The mean heel pad shock absorption was 1.1 times for EVA foam and 2.1 times for Sorbothane. The shock absorption varied by as much as 100% between heel pads. Trauma caused a decrease in the heel pad shock absorbency (24%), whereas heel pad confinement increased the shock absorbency (49% in traumatized heel pads and 29.5% in nontraumatized heel pads). These findings provide a biomechanical rationale for the clinical observations of a correlation between heel pad shock absorbency loss and heel strike-dependent overuse injuries. To increase shock absorbency, confinement of the heel pad should be attempted in vivo.
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Jørgensen, Uffe, Eilif Larsen, and Jens Erik Varmarken. "The HPC-Device: A Method to Quantify the Heel Pad Shock Absorbency." Foot & Ankle 10, no. 2 (October 1989): 93–98. http://dx.doi.org/10.1177/107110078901000208.
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Previous studies have indicated that the shock absorbency of the heel pad is significant in the pathophysiology of pain conditions connected with heel strike. The purpose of this study was to develop a simple clinically usable method for quantification of the heel pad shock absorbency. The results of our efforts was the HPC-device which consists of a fixing device and a transducer. The HPC-device was found suitable in the evaluation of the heel pad force/deformation characteristics. The reproducibility of heel pad deformation was 0.96. Tests of six cadaver heel pads revealed a high correlation between the HPC result and the shock absorbency found by drop tests. In a normal material (200 heel pads), it was found that the shock absorption decreased with age and that men had significantly higher shock absorbency than women. Men also had significantly thicker heel pads than women. However, there was no linear correlation between the thickness of the heel pad and the shock absorbency, although the thinnest heel pads had the lowest shock absorbency. The HPC-device was found clinically usable and will be used in further testing of the significance of heel pad shock absorption for the development of heel strike dependent over-use injuries.
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Peacock, Robert, and Gary Cordner. "“Shock Therapy” in Ukraine: A Radical Approach to Post-Soviet Police Reform." Public Administration and Development 36, no. 2 (May 2016): 80–92. http://dx.doi.org/10.1002/pad.1748.
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Jørgensen, Uffe. "Achillodynia and loss of heel pad shock absorbency." American Journal of Sports Medicine 13, no. 2 (March 1985): 128–32. http://dx.doi.org/10.1177/036354658501300209.
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Leffingwell, James W. "Unitary shock‐absorbing polymeric pad for artificial turf." Journal of the Acoustical Society of America 79, no. 6 (June 1986): 2104. http://dx.doi.org/10.1121/1.393141.
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Knight, Kathryn. "Shock-absorbing pad protects whales’ jaws when dining." Journal of Experimental Biology 223, no. 7 (April 1, 2020): jeb224642. http://dx.doi.org/10.1242/jeb.224642.
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Knight, Kathryn. "Retraction: Shock-absorbing pad protects whales’ jaws when dining." Journal of Experimental Biology 223, no. 12 (June 15, 2020): jeb230771. http://dx.doi.org/10.1242/jeb.230771.
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Nagarajan, Balasubramanian, Sylvie Castagne, Zhong Ke Wang, and Hong Yu Zheng. "Finite Element Analysis of the Effect of Flexible Pad on the Deformation of Metal Foils in Flexible Pad Laser Shock Microforming." Key Engineering Materials 611-612 (May 2014): 581–88. http://dx.doi.org/10.4028/www.scientific.net/kem.611-612.581.
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Flexible Pad Laser Shock Forming (FPLSF) is a new microforming process using laser-induced shock pressure and a flexible pad. This process involves high strain-rate (~105 s-1) plastic deformation of metallic foils along with the hyperelastic deformation of the flexible elastomer pad over which the foil is positioned. This paper studies the influence of flexible pad on the shockwave propagation behavior and the plastic deformation of metal foil in FPLSF using finite element analysis. The effect of flexible pad materials such as silicone rubber, polyurethane rubber and natural rubber on the deformation of copper foils has been analysed in detail. An increase in crater depth is observed with the reduction in flexible pad hardness. However, it is found that there exists an optimum hardness of the flexible pad to achieve perfect hemispherical craters on metal foils, as bending of foils at non-deformed region is observed with softer pads whereas flattening of crater surface occurs with harder pads. The effect of flexible pad thickness on the foil deformation was analyzed at six different thickness levels: 300 μm, 600 μm, 900 μm, 1200 μm, 1500 μm, and 2000 μm. Similarly, there exists an optimum flexible pad thickness to maximize the crater depth and achieve the hemispherical shapes. Analysis of flexible pad thickness indicates that the pad thickness influences the elastic recovery of the flexible-pad and hence the plastic deformation of the metallic foils.
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Collins, Paul, and Frederick Nixson. "Managing the implementation of ‘shock therapy’ in a landlocked state: Mongolia's transition from the centrally planned economy." Public Administration and Development 13, no. 4 (October 1993): 389–407. http://dx.doi.org/10.1002/pad.4230130407.
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Jung, Donghyuck, Changkyoo Park, Eun-Joon Chun, and Yoon-Jun Kim. "Improvement of Wear Resistance in Laser Shock-Peened Copper Contacts." Korean Journal of Metals and Materials 58, no. 8 (August 5, 2020): 560–65. http://dx.doi.org/10.3365/kjmm.2020.58.8.560.
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This study investigated the influence of laser shock peening without coating (LSPw/oC) on the degradation of copper electrical contacts. A theoretical calculation of the plastic-affected depth (PAD) induced by LSPw/oC was performed, based on the laser-induced plasma pressure along with the Hugoniot elastic limit of our LSPw/oC experimental conditions. The theoretical PAD was obtained approximately 650 µm from the surface for the LSPw/oC at the laser energy density of 5.3 GW/cm2. Various characterization methods such as the Vicker’s hardness test, residual stress test, and electron backscattered diffraction (EBSD) mapping indicated the PAD may play a significant role in laser induced effective depth for LSPw/oC. At a laser energy density of 5.3 GW/cm2, the laser shock-peened copper showed approximately double the surface hardness as compared to the pure copper. This was attributed to grain refinement, which was confirmed by measuring average grain sizes, and by observing mechanical twin structures from the EBSD analysis. Additionally, a compressive residual stress was induced down to the PAD but gradually switched to a tensile residual stress below PAD. The surface hardening effect conferred by LSPw/oC to the pure copper surface resulted in excellent wear resistance, i.e., a low coefficient of friction and wear loss. As a result, the contact exhibited lower electrical resistance following the fretting friction test compared to pure copper; this would result in a significant delay in electrical contact failure.
Dissertations / Theses on the topic "Shock Pad"
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Scott, Michael Brian. "General relativistic shock-waves propagating at the speed of light /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
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Hamdoun, Amro M. "Molecular physiology of stress tolerance in marine invertebrates : the heat shock response and multidrug resistance /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Brahmi, Nassim. "Etude numérique de la propagation et l’atténuation des ondes de choc en milieux confinés Turbulent structures of shock-wave diffraction over 90° convex corner Analysis of shock-wave diffraction over double concave cylindrical wedges. Part I: Shock dynamics Analysis of shock-wave diffraction over double cylindrical wedges. Part II: Vorticity generation Achieving an optimal shock-wave mitigation inside open channels with cavities for weak shock waves: a computational study." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMIR09.
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La propagation des ondes de choc implique des interactions complexes entre ondes et milieux environnants, ce qui engendre plusieurs phénomènes tels que la réflexion, la diffraction, etc. Pour clarifier davantage la physique associée à ces phénomènes, des simulations numériques hautes résolutions ont été réalisées. En particulier l'analyse de la diffraction des ondes de choc sur deux surfaces concaves cylindriques a révélé que les angles de transition, d'une réflexion régulière à une réflexion de Mach, augmentent avec le nombre de Mach, alors qu'ils sont presque égaux sur les deux surfaces concaves pour les régimes de Mach transsoniques et relativement plus important sur la deuxième surface pour les nombres de Mach plus élevés. Ceci prouve que l'écoulement est en mesure de conserver l'historique des événements passés sur l'ensemble du processus pour des nombres de Mach élevés. L'analyse de l'équation de transport de vorticité a montré, pour la première fois, que la diffusion de la vorticité due aux effets visqueux est assez importante par rapport au terme baroclinic pour les faibles nombres de Mach, alors que cette tendance est inversée pour les nombres de Mach les plus élevés. L'étude a également montré que le stretching de la vorticité dû aux effets de compressibilité joue un rôle important dans la production de vorticité. A la base de ces simulations numériques, une relation universelle a été proposée, permettant de prédire la trajectoire et la vitesse de l'onde incidente en fonction du nombre de Mach incident, du rayon de courbure de la géométrie et des propriétés du gaz. Par la suite, l'étude de la propagation des ondes de choc et leur atténuation dans des conduites de différentes hauteurs et présentant des cavités circulaires creuses de différentes profondeurs a été effectuée. Les résultats ont montré l'importance de la réduction de la hauteur du canal et le changement de la position de la section réduite en plus de l'angle de diffraction et de la profondeur de la cavité pour une meilleure atténuation des ondes. Un arrangement optimal de la position/hauteur du canal et de l'emplacement / profondeur de la cavité a été trouvéThe propagation of shock waves involves complex interactions between waves and surrounding media, which gives rise to several phenomena such as reflection, diffraction, etc. To shed more light into the fundamental physics associated with these phenomena, high resolution numerical simulations were carried out. In particular, analysis of shock diffraction over double concave cylindrical wedges revealed that the transition angles, from regular to Mach reflection, increase with the Mach number, whereas they are found to be almost the same over the two concave surfaces for the transonic Mach regimes and relatively larger on the second surface for high ones showing that the flow is capable of retaining the memory of the past events over the entire process for the high Mach numbers. The analysis of the vorticity equation balance showed, for the first time, that the diffusion of the vorticity due to the viscous effects is quite important compared to the baroclinic term for low Mach numbers, while this trend is inverted for higher Mach numbers. The study also showed that the stretching of the vorticity due to the compressibility effects plays an important role in the vorticity production. On the basis of these numerical simulations, an approximate universal relation is proposed, allowing to predict the incident-shock trajectory and velocity as a function of the incident-shock Mach number, the radius of curvature of the geometry, and the gas properties. Afterward, the study of shock-waves propagation and their attenuation in channel flow having different heights and exhibiting a hollow circular cavities with different depths has been clone. The results also showed the importance of reducing the height of the channel and changing the position of the reduced section in addition to the diffraction angle and the cavity depth for better shock-waves attenuation. A subtle arrangement of channel position/height and a cavity location/depht was found
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Vallet, Alexandra. "Hydrodynamic modelling of the shock ignition scheme for inertial confinement fusion." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0214/document.
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Le schéma d'allumage par choc pour la fusion par confinement inertiel utilise une impulsion laser intense à la fin d'une phase d'assemblage de combustible. Les paramètres clefs de ce schéma sont la génération d'une haute pression d'ablation, l'amplification de la pression du choc généré par un facteur supérieur à cent et le couplage du choc avec le point chaud de la cible. Dans cette thèse, de nouveaux modèles semi-analytiques sont développés afin de décrire le choc d'allumage depuis sa génération jusqu'à l'allumage du combustible. Tout d'abord, un choc sphérique convergent dans le coeur pré-chauffé de la cible est décrit. Le modèle est obtenu par perturbation de la solution auto-semblable de Guderley en tenant compte du nombre de Mach du choc élevé mais fini. La correction d'ordre un tient compte de l'effet de la force du choc. Un critère d'allumage analytique est exprimé en fonction de la densité surfacique du point chaud et de la pression du choc d'allumage. Le seuil d'allumage est plus élevé pour un nombre de Mach faible. Il est montré que la pression minimale du choc, lorsqu'il entre dans le coeur de la cible, est de 20Gbar. La dynamique du choc dans la coquille en implosion est ensuite analysée. Le choc se propage dans un milieu non inertiel avec un fort gradient de pression et une augmentation temporelle générale de la pression. La pression du choc est amplifiée plus encore durant la collision avec une onde de choc divergente provenant de la phase d'assemblage. Les modèles analytiques développés permettent une description de la pression et de la force du choc dans une simulation typique de l'allumage par choc. Il est démontré que, dans le cas d'une cible HiPER, une pression initiale du choc de l'ordre de 300 Mbar dans la zone d'ablation est nécessaire. Il est proposé une analyse des expériences sur la génération de chocs forts avec l'installation laser OMEGA. Il est montré qu'une pression du choc proche de 300Mbar est atteinte près de la zone d'ablation avec une intensité laser absorbée de l'ordre de 2 X 10(15) W.cm-2 et une longueur d'onde de 351 nm. Cette valeur de la pression est deux fois plus importante que la valeur attendue en considérant une absorption collisionnelle de l'énergie laser. Cette importante différence est expliquée par la contribution d'électrons supra-thermiques générés durant l'interaction laser/plasma dans la couronne. Les modèles analytiques proposés permettent une optimisation de l'allumage par choc lorsque les paramètres de la phase d'assemblage, sont pris en compte. Les diverses approches analytiques, numériques et expérimentales sont cohérentes entre-ellesThe shock ignition concept in inertial confinement fusion uses an intense power spike at the end of an assembly laser pulse. the key feature of shock ignition are the generation of a high ablation pressure, the shock pressure amplification by at least a factor of a hundred in the cold fuel shell and the shock coupling to the hot-spot. in this theses, new semi-analytical hydrodynamic models are developed to describe the ignitor shock from its generation up to the moment of fuel ignition. A model is developed to describe a spherical concerging shock wave in a pre-heated hotspot. The self-similar solution developed by Guderley is perturbed over the shock Mach number Ms >>1. The first order correction accounts for the effects of the shock strength. An analytical ignition criterion is defined in terms of the shock strength ans th hot-spot areal density. The ignition threshold is higher when the initial Mach number of the shock is lower. A minimal shock pressure of 20 Gbar is needed when it enters the hot-spot. The shock dynamics in the imploding shell is the analyzed. The shock is propagating into a non inertial medium with a high radial pressure gradient and an averall pressure increase with time. The collision with a returning shock coming from the assembly phase enhances further the ignitor shock pressure. The analytica theory allows to des cribe the shock pressure and strength evolution in a typical shock ignition implosion. It is demonstrated that, in the case of the HiPER target design, a generation shock pressure near the ablation zone on the order of 300-400 Mbar is needed. An analysis of experiments on the strong shock generation performed on the OMEGA laser facility is presented. It is sown that a shock presssure close to 300 Mbar near the ablation zone has been reached with an absorbed laser intensity up to 2 x 10(15) W:cm-2 and a laser wavelength of 351 nm. This value is two times higher than the one expected from collisional laser absorption only. That significant pressure enhancement is explained by contribution of hot-electrons generated by non-linear laser/plasma interaction in the corona. The proposed analytical models allow to optimize the shock ignition scheme, including the inuence of the implosion parameters. Analytical, numerical and experimental results are mutualy consistent
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Giral, Pérez Marta. "Estudio del efecto de los antagonistas del factor activador de las plaquetas (PAF) en varios modelos de shock experimental." Doctoral thesis, Universitat Autònoma de Barcelona, 1997. http://hdl.handle.net/10803/5367.
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El shock es una situación clínica que se ha venido observando durante cientos de años y cuya presencia ha ido asociada con procesos que culminaban casi siempre con la muerte. El estudio de estos procesos ha permitido llegar a la conclusión de que el shock tiene un componente multifactorial y multietiológico. La cascada de eventos que tienen lugar en un estado de shock parece demasiado compleja como para que la actuación terapéutica sobre uno solo de estos pasos sea suficiente como para bloquear el shock en su conjunto. Sin embargo, desde hace años se vienen estudiando diferentes aproximaciones terapéuticas entre las que se encuentra el antagonismo del factor activador de ls plaquetas (PAF). Los diferentes trabajos desarrollados en esta tesis pretenden ser una aportación al estudio del papel del PAF y de sus antagonistas en el shock. Para ello se han recogido una serie de modelos experimentales, tanto in vitro como in vivo , con el antagonista del PAF UR-12460. Los modelos estudiados son: shock anafiláctico, shock por isquemia-reperfusión esplácnica y coronaria, shock endotóxico y shock hemorrágico. El UR-12460 presenta actividad en modelos de shock anafiláctico activo, tanto en cobayo como en ratón. Además, para una serie de antagonistas del PAF estudiados, se demuestra una buena correlación entre la inhibición de la mortalidad inducida por PAF y la inhibición de la mortalidad inducida por shock anafiláctico activo en ratón, lo cual indica que el PAF está implicado en estos procesos. La ineficacia del UR-12460 en procesos de shock pasivo sugiere una menor importancia relativa del PAF con respecto a otros mediadores como la histamina. Por otra parte, en modelos de shock por isquemia-reperfusión esplácnica en rata, el UR-12460 se ha mostrado parcialmente efectivo, inhibiendo la mortalidad y la trombocitopenia producidas por el shock. Otro modelo de isquemia-reperfusión, pero a nivel miocárdico en este caso, ha sido extensamente estudiado en la rata. La oclusión durante 6 minutos de la arteria coronaria izquierda en la rata anestesiada, y posterior reperfusión durante 10 minutos, produce una serie de alteraciones del ritmo cardíaco que son inhibidas por el UR-12460. Dicho compuesto disminuye la incidencia de taquicardias ventriculares durante la oclusión, y disminuye la aparición de fibrilación ventricular en la reperfusión. Esto apoya el papel del PAF en la arritmogénesis por isquemia-reperfusión. Las pruebas de isquemia-reperfusión en corazón aislado de rata, por el método de Langendorff, combinadas con la incubación posterior del tejido cardíaco con cloruro de trifeniltetrazolio, permiten aunar en un mismo experimento y bajo las mismas condiciones, la valoración macroscópica del área de infarto y la alteración funcional del corazón. En este modelo los corazones se perfunden con sangre diluida en líquido de Krebs y se comparan con corazones que reciben sólo el diluyente. Las marcadas diferencias entre los corazones isquémicos que han recibido sangre diluida y los que no, sugieren que las células sanguíneas son pieza clave en la génesis de los infartos y en el deterioro del funcionalismo cardíaco. Por otra parte, la ausencia de una relación directa entre el tiempo de isquemia-reperfusión y la gravedad del infarto, en ausencia de sangre, sugiere que la situación de anoxia no es un factor determinante en la génesis del infarto. Sí existe relación entre el tiempo de isquemia-reperfusión y las alteraciones de la función mecánica. La presencia de células sanguíneas podría representar un sistema de amplificación del daño causado por la anoxia. Los resultados obtenidos en este modelo con el compuesto UR-12460 y el antioxidante mercaptopropionilglicina sugieren que tanto el antagonismo del PAF como la captación de radicales libres pueden ser útiles en la disminución del infarto y, en general, en la mejoría de la función miocárdica durante la reperfusión y en la disminución de las arritmias.Otro importante modelo es el shock endotóxico, inducido en la rata por la administración de lipopolisacárido (LPS) de E. coli de diversos serotipos. El serotipo 0111:B4 produce un característico efecto bifásico de hipotensión arterial. El UR-12460 no inhibe la profunda e inmediata fase de hipotensión pero sí la segunda fase, más lenta y progresiva. Utilizando el serotipo 0127:B8 se ha estudiado el aumento de permeabilidad vascular en la rata. Se ha comprobado que sólo algunos órganos resultan afectados significativamente y que el aumento de permeabilidad se aprecia a partir de los 15 minutos de administrado el LPS. Por otra parte, hay una buena correlación entre la inhibición de la mortalidad inducida por PAF y la inducida por LPS en ratón, lo que refuerza la participación del PAF como mediador clave en la cascada de acontecimientos que producen la mortalidad por LPS. Este papel queda reforzado por la eficacia mostrada por el UR-12460 al atenuar las alteraciones bioquímicas y enzimáticas inducidas por LPS en rata. La inhibición del aumento del tiempo parcial de tromboplastina activada indica que el PAF puede estar también implicado en los mecanismos que conducen al síndrome de coagulación intravascular diseminada en la rata. El último modelo estudiado es el shock hipovolémico hemorrágico, en el cual la eficacia de los antagonistas probados no se ha demostrado. Es posible que su administración sólo sea beneficiosa en fases iniciales de la hemorragia, cuando el shock no se ha hecho todavía progresivo o no se han liberado otros mediadores.
En resumen, puede decirse que el UR-12460 se ha mostrado activo, al menos parcialmente, en varios modelos de shock, reforzando la idea de la participación importante del PAF en estos procesos de tan diversa etiología. Sin embargo, el hecho de que este compuesto no tenga efecto sobre algunos de los marcadores del shock estudiados hace pensar que el futuro de un posible tratamiento del shock pasaría por la administración conjunta de diferentes sustancias, dirigidas cada una a los diferentes mediadores del shock que, además del PAF, intervienen en mayor o menor grado en su etiopatogenia.
Shock is a clinical situation that has been observed for centuries and whose presence has been associated to processes leading usually to death. The study of these processes has allowed to reach the conclusion that shock is a multifactorial and multietiological component syndrome. Since the cascade of events that take place during shock is very complex, it seems unlikely that acting on a single of its steps may be sufficient to block the shock state in its entirety. Nevertheless, in the last years different therapeutic approaches are being studied, among them the antagonism of platelet activating factor (PAF). The different studies carried out in this thesis intend to be a contribution to the study of the role of PAF and of its antagonists in shock. With a view to this we have performed several experimental models, both in vitro and in vivo, using UR-12460, a potent and selective PAF antagonist. The studied models are: anaphylactic shock, splachnic and coronary ischemia-reperfusion-induced shock, endotoxic shock and hemorrhagic shock. UR-12460 was found to be effective in active anaphylactic shock models, both in guinea pigs and mice. Furthermore, for a series of PAF antagonists, we have observed a good correlation between the inhibition of PAF-induced mortality and of active anaphylactic shock -induced mortality in mice, which indicates that PAF is involved in these processes. The ineffectiveness of UR-12460 in passive shock processes suggests a minor relative importance of PAF with respect to other mediators such as histamine. On the other hand, in splachnic ischemia-reperfusion (ischemia-reperfusion) shock models in the rat, UR-12460 has been shown partially effective, inhibiting the mortality and thrombocytopenia induced by shock. Another model of ischemia-reperfusion, but at myocardial level in this case, has been extensively studied in the rat. The occlusion during 6 minutes of the left coronary artery in the anesthetized rat, and subsequent reperfusion during 10 minutes, produces a number of disturbances in cardiac rhythm that are inhibited by UR-12460. This compound reduces the incidence of ventricular tachycardia during the occlusion phase as well as the onset of ventricular fibrillation in the reperfusion. This finding supports the role of PAF in the arrhythmogenesis by ischemia-reperfusion. The ischemia-reperfusion tests in isolated rat heart using the Langendorff method, combined with the subsequent incubation of the cardiac tissue with triphenyltetrazolium chloride, allow to combine in a single experiment, and under identical conditions, the macroscopic assessment of the infarcted area and the functional alterations of the heart. In this model, hearts are perfused with blood diluted with Krebs solution and are compared with hearts receiving only Krebs. The marked differences observed between the ischemic hearts that have received diluted blood and those that have not suggest that blood cells are a key factor in the genesis of infarction and in the impairment of cardiac function. On the other hand, the absence of a direct relationship between the time of ischemia-reperfusion and the severity of the infarction in the absence of blood suggests that the situation of anoxia is not a relevant factor in the genesis of infarction. There is indeed a relationship between the time of ischemia-reperfusion and the impairment of the mechanical function. The presence of blood cells may represent an amplification system of the damage caused by the anoxia. The results obtained in this model with the compound UR-12460 and the antioxidant mercaptopropionylglycine suggest that both PAF antagonism and free radical scavenging may be useful to reduce infarction and, in general, to improve the myocardial function during reperfusion and to reduce arrhythmias.
Another important model is the endotoxic shock, which is induced in the rat by the administration of E. coli lipopolysaccharide (LPS) of different serotypes. Serotype 0111:B4 produces a characteristic biphasic effect of arterial hypotension. UR-12460, although not able to inhibit the steep and immediate phase of hypotension, clearly inhibits the second phase, which is slower and more progressive. The increase in vascular permeability has been studied in the rat using serotype 0127:B8. We have observed that only some organs are significantly affected and that the increase in permeability is noticeable from 15 minutes post-administration of LPS. UR-12460 has been shown to inhibit extravasation in the trachea and seminal vesicle. On the other hand, we have observed a good correlation between the inhibition of the mortality induced by PAF and that induced by LPS in the mouse, which fact reinforces the involvement of PAF as a key mediator in the cascade of events that cause the mortality by LPS. This is additionally supported by the ability shown by UR-12460 to reduce the biochemical and enzymatic alterations induced by LPS in the rat. The inhibition of the increase in the activated partial thromboplastin time shows that PAF may also be involved in the mechanisms leading to disseminated intravascular coagulation syndrome in the rat. The last shock model we have studied is the hemorrhagic hypovolemic shock, where none of the antagonists tested has proved effective. It is possible that their administration may only be beneficial in the initial stages of hemorrhage, when shock has not yet become progressive or other mediators have not yet been released.
To sum up, it can be said that UR-12460 has proved effective, at least partially, in several models of shock, reinforcing the theory that PAF has a key role in these processes of such diverse etiology. However, the fact that this compound has no effect on some of the shock markers studied in this thesis brings us to think that the future of a possible treatment for shock requires the administration of different substances, directed to each one of the different mediators of shock that, in addition to PAF, are involved to a greater or lesser extent in its etiopathogenesis.
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Haj, Montaser A. "The influence of neutrophils and mononuclear leucocytes on the fibrinolytic response to severe sepsis." Thesis, University of Aberdeen, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295797.
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This study identified striking increase in plasma of plasminogen activator inhibitor 1(PAI-I), a major inhibitor of fibrinolysis levels in septic patients who are non-neutropenic. Neutropenic patients show less striking changes. Where shock occurs both groups of patients show very high levels of PAI-1. These observations suggest a role for leucocytes in PAI production. In the second section neutrophils are identified as containing PAI-1 in normal subjects, the levels rising significantly in sepsis. Monocytes contain no PAI-1 but do contain Plasminogen activator inhibitor 2(PAI-2) levels of which inhibitor also rise in sepsis. Normal neutrophils contained no PAI-2 but neutrophils from septic patients contained significant quantities of this inhibitor. In the third section mononuclear cells from septic patients are identified as enhancing PAI-1 production in cultured endothelial cell (EC). Septic neutrophils have a more complex effect on EC. Mononuclear cells and neutrophils therefore, both contribute to the fibrinolytic inhibition of septic disorders but by different mechanisms. Each cell type contains one of the major inhibitor of plasminogen activator and levels of these rise in sepsis. Both cell types from septic patients promote greater release of PAI-1 from endothelial cells than do cells from normal individuals. Inhibition of fibrinolysis by leucocytes may contribute to fibrin persistence in sepsis. This may be useful in localizing infection. If generalized, it may contribute to vascular occlusive complications of sepsis such as shock lung, acute renal failure or digital gangrene. Absence of leucocytes may account for the apparent reduction of vascular occlusive complications in leucopenic septic patients.
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Shin, Hyung-Cheol. "Determinants of an optimal exchange rate regime : production composition, economic size, shock structure, consumption habits, and presence of "original sin" /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
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Fang, Lin. "Mechanism of client protein binding by heat shock protein 90 /." view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1251819301&sid=2&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Thesis (Ph. D.)--University of Oregon, 2006.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 115-121). Also available for download via the World Wide Web; free to University of Oregon users.
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Llor, Aisa Emma. "Génération de très hautes pressions d'ablation laser et de chocs forts pour l'allumage des réactions de fusion nucléaire." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0013/document.
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Le schéma d'allumage par choc est une approche prometteuse pour obtenir de l'énergie à grande échelle. Cependant, ce schéma requière des pressions d'ablation laser de l'ordre de 300-400 Mbar pour atteindre l'allumage. L'objectif de cette thèse est de mieux comprendre la physique sous-jacente de la génération de ces pressions très élevées par les mécanismes du transport de l'énergie par les électrons énergétiques dans un régime d'intensité laser entre un et dix petawatt par cm2. Au cours de cette thèse il a été établi un modèle permettant de calculer la pression du choc induit par les électrons chauds et le temps de sa formation pour une distribution en énergie d'électrons et un profil de densité de plasma arbitraire. Nous montrons que la distribution en énergie d'électrons plus étendue conduit à un dépôt en énergie plus homogène ce qui implique un temps de formation du choc plus long et une diminution de la force du choc. Ces conséquences sont à prendre en compte pour le design des cibles pour l'allumage par choc. L'extension de ce modèle au cas d'un plasma inhomogène montre que la couronne de faible densité diminue l'énergie des électrons rapides et donc la quantité d'énergie déposée dans la cible comprimée. Ceci conduit à une réduction du temps nécessaire à la formation du choc, de la pression du choc et de l'efficacité de la conversion de l'énergie des électrons vers l'onde de choc. Ce modèle théorique nous permet d'interpréter l'expérience de la génération d'un choc sphérique sur l'installation laser OMEGA. Grâce à la comparaison des simulations numériques d'un tir représentatif aux résultats expérimentaux nous avons caractérisé la source d'électrons ainsi que la pression et la dynamique du choc. Enfin, nous proposons un design préliminaire de l'expérience sur le rôle des électrons chauds dans la création d'un choc plan sur l'installation LMJ-PETALThe Shock Ignition (SI) scheme is a promising approach to obtaining energy on alarge scale. However, this scheme needs ablation pressures in the range of 300-400Mbar to reach ignition. The objective of this thesis is therefore to better understandthe underlying physics of high pressure generation by energetic electrons in a regimeof intensity between one and ten petawatt per cm2. In this thesis, a model hasbeen established for calculating the shock pressure generated by hot electrons andthe time of its formation for an arbitrary electron energy distribution and plasmadensity profile. It is shown that a broader electron energy distribution leads to amore homogeneous energy deposition which implies a longer shock time formationand a reduction of the shock strength. These consequences should be taken intoaccount in shock ignition target design. The extension of this model to the case ofa inhomogeneous plasma shows that the low density corona decreases fast electrons energy and then the amount of energy deposited in the compressed target. This leads to a reduction of the time needed for the shock formation, of the shock pressure and the energy invested in the shock. This theoretical model allows us to interpret the experiment performed in spherical geometry on the OMEGA laser facility. The comparison between numerical simulations and experimental results allow us to characterize the electron source as well as shock pressure and dynamic. Finally, we propose a preliminary design of an experiment to explore the hot electron role in shock generation in planar geometry on the LMJ-PETAL laser facility
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Ramey, Christopher Shane. "Post-transcriptional adaptation of Escherichia coli during the cold shock response." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1464111681&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Full textBooks on the topic "Shock Pad"
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Saff, E. B., Douglas Patten Hardin, Brian Z. Simanek, and D. S. Lubinsky. Modern trends in constructive function theory: Conference in honor of Ed Saff's 70th birthday : constructive functions 2014, May 26-30, 2014, Vanderbilt University, Nashville, Tennessee. Providence, Rhode Island: American Mathematical Society, 2016.
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3DO Games Secrets: Book Two. Maui, HI: Sandwich Islands Publishing, 1996.
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Chef and Polly the Parrot. Drawing Pad for Kids: It's Cool to Be Different and Just Be Who You Are and Shock People in a Good Way. Independently Published, 2019.
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The Shack Study Guide: Healing for Your Journey Through Loss, Trauma, and Pain. Windblown Media, 2016.
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Drelichman, Mauricio, and Hans-Joachim Voth. Prologue. Princeton University Press, 2017. http://dx.doi.org/10.23943/princeton/9780691151496.003.0001.
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This prologue provides an overview of state debts and sovereign default in the sixteenth century, looking in particular at Philip II's defaults. The debts and defaults of Philip II suggest that there is another way for financing government borrowing: prearranged reduction in what a government owes and has to pay to creditors in bad times. Indeed, lenders agreed to forego interest or extend the maturity of loans if the king experienced a bad shock. This system exhibited remarkable stability, bringing essentially the same banking dynasties together with the monarch for over half a century, providing financing and insurance. Another remarkable feature of the debt issuance system evolved by Philip II and his financiers is the stability of the banking institutions, the main innovation of which was an effective “risk transfer” mechanism.
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Ugarteche Galarza, Oscar. Historia crítica del FMI. Universidad Nacional Autónoma de México, Instituto de Investigaciones Económicas, 2009. http://dx.doi.org/10.22201/iiec.9786073032698e.2009.
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El presente Breviario es, entre otros muchos trabajos, producto de años de investigación sobre este tema y comienza con el concepto mismo de lo que es el fondo de estabilización monetario tripartito en los años treinta; pasa revista al Acuerdo de Bretton Woods construido a partir de la preocupación del Tesoro estadounidense sobre la inestabilidad financiera que acompañó la Gran Depresión. Recorre la importancia que tuvo para el Tesoro cuando la Pax american triunfó en 1944 y la decisión del presidente Nixon de cancelar las bases de dicho acuerdo, de forma inconsulta con el FMI en 1971. Terminada la Pax america, se repasa el modo en cómo se convirtió de un entre multilateral a una agencia norte-sur con dos diferentes reglas de juego y termina el libro con la creciente irrelevancia de la institución ante la crisis del 2007 en adelante, ya desprestigiada por sus shocks económicos y sus fracasadas intervenciones en Tailandia (1977) y Argentina (2001).
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Lerner, Adam B. From the Ashes of History. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780197623589.001.0001.
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This book theorizes collective trauma as a foundational force in international politics—a shock to political cultures that can both make and break international institutions. Though scholars of international relations and related disciplines have historically paid outsize attention to the onset of mass violence, as well as the changes it causes in the balance of power or security calculations, far less attention has been paid to its indirect longer-term impacts, particularly as they manifest as collective trauma. This book argues that collective trauma can not only shape the divisions between “us” and “them” that constitute the international system but also frame logics of interaction over the course of generations. The first half of the book develops a theoretical framework for understanding collective trauma as an emergent phenomenon, outlining both how it translates from individual to social (and vice versa) and how it interacts with diverse political conditions and competing priorities. The second half turns to three historical cases examining colonialism as collective trauma in post-independence India, the Holocaust’s constitutive role in Israeli foreign policy imaginaries, and the influence of the post-traumatic stress disorder diagnosis on the US global war on terror. Taken together, these cases demonstrate collective trauma’s foundational role in international politics, as well as the larger potential benefits of a “trauma turn” for the international relations discipline. This reorientation, the book demonstrates, is particularly vital as scholars work to combat the discipline’s Western bias and better account for the legacy of structural injustice and oppression.
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Axworthy, Michael. Iran. Oxford University Press, 2017. http://dx.doi.org/10.1093/wentk/9780190232955.001.0001.
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Since the beginning of recorded history, Iran/Persia has been one of the most important world civilizations. Iran remains a distinct civilization today despite its status as a major Islamic state with broad regional influence and its deep integration into the global economy through its vast energy reserves. Yet the close attention paid to Iran in recent decades stems from the impact of the 1979 revolution, which unleashed ideological shock waves throughout the Middle East that reverberate to this day. Many observers look at Iran through the prism of the Islamic Republic's adversarial relationship with the US, Israel, and Sunni nations in its region, yet as Michael Axworthy shows in Iran: What Everyone Needs to Know, there is much more to contemporary Iran than its fraught and complicated foreign relations. He begins with a concise account of Iranian history from ancient times to the late twentieth century, following that with sharp summaries of the key events since the1979 revolution. The final section of the book focuses on Iran today--its culture, economy, politics, and people--and assesses the challenges that the nation will face in coming years. Iran will be an essential overview of a complex and important nation that has occupied world headlines for nearly four decades.
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Singh, Renu, and Protap Mukherjee. Push Out, Pull Out, or Opting Out? Reasons Cited by Adolescents for Discontinuing Education in Four Low- and Middle-Income Countries. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190847128.003.0012.
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By drawing on Bronfenbrenner’s (1999) ecological framework, this mixed-method paper recognizes school discontinuation not as an event but as a culmination of an interplay of various factors over time. Adopting a life course perspective and analyzing reasons given by adolescents for “not being in school” across the four middle- and low-income Young Lives study countries, three broad categories of reasons for early school leaving emerge. These are push factors, pull factors, and opted-out factors. Findings revealed that pull factors emerge as the greatest contributor toward children discontinuing education as they enter middle and late adolescence. Besides household dynamics and shocks, boys in particular discontinue schooling due to paid work, while girls spend long hours in domestic chores at the cost of attending school. While in-school factors, particularly quality, cannot be ignored, it is important to provide social protection nets to the poorest families in order to achieve Sustainable Development Goal Goal 4.
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Jamais sans ma fille, tome 2. Pour l'amour d'un enfant. Fixot, 1994.
Find full textBook chapters on the topic "Shock Pad"
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Goldstein, R. E., F. R. M. Laurindo, D. Ezra, and G. Z. Feuerstein. "Mechanisms of Circulatory Collapse Induced by PAF-Acether." In Lipid Mediators in the Immunology of Shock, 177–85. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-0919-2_19.
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Paton, R. T., and B. W. Skews. "Shock and Blast Wave Interaction with Hard Sand Pan." In 31st International Symposium on Shock Waves 2, 673–79. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-91017-8_84.
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Ward, S. G., G. P. Lewis, and J. Westwick. "A Role for Platelet-Activating Factor (PAF) in Human T-Lymphocyte Proliferation." In Lipid Mediators in the Immunology of Shock, 483–93. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-0919-2_52.
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Rabinovici, Reuven, Tian Li Yue, Jerome Vernick, and Giora Feuerstein. "PAF and TNFα Interactions in the Pathophysiology of Septic Shock." In Cell-Cell Interactions in the Release of Inflammatory Mediators, 193–203. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4684-6024-7_12.
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Damas, J., G. Remacle-Volon, A. Adam, and V. Bourdon. "Endotoxin Shock, Kinin System and PAF-acether in the Rat." In Advances in Experimental Medicine and Biology, 547–52. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4615-9546-5_90.
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Lellouch-Tubiana, A., J. Lefort, V. Lagente, M. Cirino, M. Vargaftig, and B. B. Vargaftig. "Morphological and Pharmacological Evidences for the Participation of PAF-Acether in Anaphylactic Shock in the Guinea-Pig." In Lipid Mediators in the Immunology of Shock, 209–15. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-0919-2_22.
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Hosford, D., M. Koltai, and P. Braquet. "PAF, Cytokines and Cell to Cell Interactions in Shock and Sepsis." In Update in Intensive Care and Emergency Medicine, 152–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-84827-8_11.
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Viossat, I., P. E. Chabrier, M. Chapelat, and P. Braquet. "The Coronary, Inotropic, Chronotropic and Arrhythmogenic Effects of Paf-Acether on Isolated Guinea-Pig Heart and their Selective Inhibition by BN 52021." In Lipid Mediators in the Immunology of Shock, 513–17. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-0919-2_56.
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van de Poel, Ibo, Tristan de Wildt, and Dyami van Kooten Pássaro. "COVID-19 and Changing Values." In Philosophy of Engineering and Technology, 23–58. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-08424-9_2.
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AbstractWe study value change due to the corona pandemic. With the help of topic modelling, we analysed COVID-related news articles for changes in the frequency of how often these news articles address eleven different values. We looked at news articles from six countries (US, UK, South Africa, India, Japan, South Korea) and new articles spanning a longer period (2016–20); the latter also contained non-COVID news. We find that in the first few months of the pandemic, there is a punctuated shock in the frequency in which values are addressed. While we see a sharp increase in the value of health and safety, we see a significant decline in the values of democracy, privacy, and socio-economic equality. However, after the first months, we see a move in the opposite direction, which suggests that the punctuated shock’s effect may be cancelled over time. We also present – and offer possible explanations for – differences between countries and compare our results with the literature. We do not find evidence that the COVID-19 pandemic confronts us with a moral dilemma of health versus economic welfare, or lives versus livelihoods, as has sometimes been suggested. Our study also indicates a degree of moral resilience in the studied countries, in the sense of the ability to pay attention to morally important values, despite being put under pressure during a crisis.
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Matsuda, Kenichi, Takeshi Moriguchi, Norikazu Harii, Masahiko Yanagisawa, Daiki Harada, and Hisanori Sugawara. "Comparison of Efficacy between Continuous Hemodiafiltration with a PMMA High-Performance Membrane Dialyzer and a PAN Membrane Hemofilter in the Treatment of Septic Shock Patients with Acute Renal Failure." In Contributions to Nephrology, 182–90. Basel: KARGER, 2011. http://dx.doi.org/10.1159/000329058.
Full textConference papers on the topic "Shock Pad"
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Suriyanarayanan, P., L. Venkatakrishnan, and G. Jagadeesh. "Experimental Investigation on the Behavior of Multiple Shock Interactions Inside Launch Pad." In Proceedings of the 32nd International Symposium on Shock Waves (ISSW32 2019). Singapore: Research Publishing Services, 2019. http://dx.doi.org/10.3850/978-981-11-2730-4_0374-cd.
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DiFiore, Amanda M., Abdullatif K. Zaouk, Neil J. Mansfield, and S. K. John Punwani. "Whole-Body Vibration in Locomotive Cabs." In ASME 2011 Rail Transportation Division Fall Technical Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/rtdf2011-67016.
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Locomotives produce vibrations and mechanical shocks from irregularities in the track, structural dynamics, the engines, the trucks, and train slack movement (Mansfield, 2005). The different directions of the irregularities give rise to car-body vibrations in multiple axes including the following: • Longitudinal, or along the length of the train (x); • Lateral, or the side-to-side direction of the train (y); • Vertical (z). Some reports suggest that acceleration at the seat pan is greater than that at the floor, indicating that the seat may amplify the vibration (Johanning, et al., 2006; Mansfield, 2005; Oborne & Clarke, 1974; Transport, 1980). The magnitude of vertical vibration in rail vehicles is reportedly well below many other types of vehicles (Dupuis & Zerlett, 1986; Griffin, 1990; Johanning, 1998). However, some research reports that rail vehicles experience far more lateral vibratory motion than cars and trucks (Lundstrom & Lindberg, 1983). Many factors influence the impact of shock felt by the engineer including train speed, consist, engineer control skills, anticipation of the shock, motion amplitude, shock duration, and body posture. Shock events and vibration affect ride quality; however, shocks are less controllable by locomotive design. Common sources of mechanical shock are coupling and slack run-ins and run-outs (Multer, et al., 1998). While there are investigations of whole-body vibration (WBV) in locomotive cabs reported in the literature, there have been no studies to date that have examined long-haul continuous vibrations (> 16 hr). The authors describe a long-haul WBV study collected on a 2007 GE ES44DC locomotive. It is the first in a series of studies sponsored by the Federal Railroad Administration (FRA) to examine WBV and shock in locomotive cabs. The researchers recorded vibration data using 2 triaxial accelerometers on the engineers’ seat: a seat pad accelerometer placed on the seat cushion and a frame accelerometer attached to the seat frame at the base. Data collection occurred over 550 track miles for 16hr 44min. ISO 2631-1 defines methods for the measurement of periodic, random and transient WBV. The focus of ISO 2631-5 is to evaluate the exposure of a seated person to multiple mechanical shocks from seat pad measurements. The research team collected and analyzed vibrations in accordance with ISO 2631-1 and ISO 2631-5. The results from the study as well as future planned long-haul studies will provide a benchmark set of WBV metrics that define the vibration environment of present-day locomotive operations.
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Zhang, Timothy G., A. H. Fulton, K. Ravi-Chandar, and Sikhanda S. Satapathy. "Rate Dependent Material Model for Helmet Pads." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23970.
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Abstract Foam pads are commonly used in sports and military helmet for energy absorption, form-fitting and comfort. Both for low velocity and high velocity applications, their rate-dependent mechanical properties need to be characterized to understand their ability to effectively modulate the transmitted stress pulse. Impact experiments were conducted on bilayer helmet pads at a range of velocities covering low to medium rates up to ∼7000/s. Images from high-speed camera were used to construct x-T diagrams to measure the shock speeds from the impact experiments. Numerical simulations were carried out to validate a foam pad model and to understand experimental uncertainties. The scatter in the measured shock speeds was found to be related to the scatter in the material properties.
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Barnett, Ralph L., and James R. Wingfield. "On the Safety of Heating Pads." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-66048.
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The electric heating pad represents one of the medical devices that escaped the FDA safety net by a “grandfather” exemption. An amazing number of philosophical safety issues are introduced by this relatively innocuous commodity. Pain relief is a major attribute of heating pads followed by a minor in actual medical efficacy associated with the improvement of local blood circulation. By contrast, the historic downside is very dramatic featuring electrocution, fire, and skin burns. This paper begins with a brief introduction to current protocol for placing new medical devices into the stream of commerce. In the case of heating pads, it is fortunate that the Underwriters Laboratories Inc. developed and promulgated design rules that effectively mitigated the dangers of shock/electrocution and fire. On the other hand, UL has not undertaken a technical program that addresses the skin burn problem that is the focus of this paper. Nevertheless, many heating pad manufacturers are under the impression that their compliance with UL 130 has ameliorated the skin burn propensity of their pads. Heating pad manufacturers have attempted to control skin burn injuries exclusively through the means of on-product and in-manual warnings that have been promulgated by UL, FDA, and CPSC. This approach has tenaciously maintained a burn rate of 1600 cases per year. A different approach to the skin burn problem is automatically orchestrated by invoking the “Safety Hierarchy.” For example, falling asleep and causing prolonged skin exposures to a heated pad can be eliminated by a dead-man control. Exposure to extreme temperatures that arise when both faces of the pad are concurrently covered is perhaps the most prevalent cause of skin burns. This paper exploits the notion of monitoring both face temperatures and shutting off the pad when they are almost the same. We also explored shutting down the pad when the cycle rate of the bang-bang controls was sufficiently slow; higher heating rates are associated with an uncovered face.
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Tasker, Douglas G., Young K. Bae, Carl Johnson, Kevin Rainey, Christopher Campbell, Dave Oschwald, and Cornelius Reed. "Voitenko experiments with novel diagnostics detect velocities of 89 km/s." In 2019 15th Hypervelocity Impact Symposium. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/hvis2019-081.
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Abstract Using a Voitenko accelerator [1-3], a series of experiments were performed with the goal of attaining shock velocities in gases approaching 90 km/s. Typically, the basic apparatus comprises a hemispherical bowl filled with a gas at atmospheric pressure; a metal piston across its diameter; and a small bore evacuated shock tube at its apex, Fig. 1. The evacuated shock tube is separated from the gas bowl by a thin diaphragm. A combination of a plane wave explosive lens and a high explosive pad accelerates the piston to a velocity of the order of 4 km/s and subsequently compresses the gas in the bowl. The thin diaphragm at the other end of the bowl then ruptures and the high pressure (shock compressed) gas escapes into the shock tube.
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Koziol, Madison, Yutaka Suzuki, Siva Gurrum, and Muhammad Khan. "Die Attach Delamination Analysis and Modeling Between Temperature Cycling and Thermal Shock for Exposed Pad Lead Frame Devices." In 2018 IEEE 68th Electronic Components and Technology Conference (ECTC). IEEE, 2018. http://dx.doi.org/10.1109/ectc.2018.00071.
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San Andre´s, Luis, and Keun Ryu. "Dynamic Forced Response of a Rotor-Hybrid Gas Bearing System Due to Intermittent Shocks." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59199.
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Gas bearings in microturbomachinery (MTM) offer significant system level benefits, such as improved fuel efficiency, reduction in weight and number of components, extending life cycle and maintenance intervals, and reducing NOX emissions with a lower CO2 footprint. Emerging opportunities for gas bearings applications range from automotive turbochargers to engines for business jet aircraft, for example. Gas bearings, because of the inherently low gas viscosity, have low damping relative to oil-lubricated bearings and are prone to wear during rotor start-up and shut down procedures. The lack of damping brings concerns about rotor-gas bearing system robustness and endurance to tolerate shock induced loads, sudden while landing in jet engines, or intermittent in vehicles while moving across a rough terrain, for example. The paper demonstrates the reliability of a hybrid gas bearing system from rotor vibration measurements induced by sporadic shock loads acting on the base of a test rig and while the rotor is coasting down from a top speed of 60 krpm (1000 Hz). In the tests, (1) an electromagnetic pusher delivers impacts to the rig base, or (2) the whole rig is manually tilted and dropped. The test rig consists of a rigid rotor, 0.825 kg and 28.6 mm in diameter, supported on two flexure pivot tilting pad type, hybrid gas bearings, each with four pads and 60% pivot offset and 0.6 mm feeding holes. The bearings are supplied with feed pressures of 2.36, 3.72, and 5.08 bar (ab). Intermittent shocks, up to 30 g pk-pk and exciting a broad frequency range to 400 Hz, produce a remarkable momentary increase of the overall rotor response amplitude, up to 50 μm (pk-pk). The shocks readily excite the fundamental natural frequency of the rotor-bearing system (150–200 Hz), and on occasion the natural frequency (40 Hz) of the whole test rig. For operation at rotor speeds above the system critical speed, the rotor synchronous response is isolated; with transient motions induced by a shock, subsynchronous in whirl frequency, quickly disappearing. Full recovery takes place in ∼0.10 second. The measurements demonstrate that the hybrid gas bearings have enough damping to rapidly attenuate rotor transient motions and to dissipate the energy induced from intermittent shocks. Note that the shocks acted while the rotor traversed its critical speeds. The reliability of engineered gas bearings to forced transient events is no longer in question.
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Hargather, Michael J., Joshua L. Smith, James Anderson, and Kyle Winter. "Optical Diagnostics for Energetic Materials Research." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-67372.
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Optical diagnostics including schlieren, shadowgraphy, and background-oriented schlieren (BOS) are used to visualize shock waves and compressible flow phenomena present in energetic and explosive events. These techniques visualize refractive index variations to obtain a range of qualitative and quantitative information. A one-dimensional explosively-driven shock tube facility is used with schlieren imaging to measure shock wave propagation speeds from explosive-thermite mixtures. The schlieren imaging visualizes turbulent flow structures in the expanding product gas region. An imaging spectrometer is paired with the schlieren imaging to quantify the mixing of the explosive product gases with the ambient environment. Shadowgraphy is applied to image field-scale explosive tests. The shadowgraph images reveal shock waves, fragment motion and speed, and the motion of product gases. BOS is a modern technique for visualizing refractive fields via their distortion of a background pattern. Here the technique is applied to image field-scale explosive events using the ambient background of the test pad. The BOS images clearly show shock wave propagation and reflection from surfaces, which is not clearly visible in the raw high-speed digital images.
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Sahasrabudhe, Shubhada, Vinayak Pandey, Betty Phillips, Kang Joon Lee, and Lei Mercado. "Use-Conditions-Based Board Level Shock Test Development for Handheld Components." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-60121.
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For handheld electronic applications such as cell phones and Personal Digital Assistants (PDAs), drop/impact could result in considerable flexure of the printed circuit board (PCB) mounted inside the cell phone housing. The mechanical stresses may cause electrical failure of the components, with typical failure mechanisms of board trace cracking, solder joint fatigue, and solder pad cracking. A standardized test needs to be developed to assess reliability of handheld components subjected to impacts. The test should facilitate high volume testing, maximize margin for safety factors, and capture the failure mechanisms in the field environment. To develop the reliability test using use conditions based reliability methodology, comprehensive characterization of the mechanical field stresses during end use conditions is particularly essential. This paper discusses complete cell phone drop characterization along with the shock test developed to test the components subjected to such drops. Novel fixtures have been designed to simulate free fall of the cell phone in specific orientations. After the complete characterization of cell phone use conditions, board level shock test has been selected to assess component reliability. Test repeatability, number of components on the test board, and layout of the components are some of the factors considered during the board level shock test development. Several parameters like screw and washer designs, torque have been studied to yield excellent test repeatability. Nonlinear Dynamic Finite Element Simulation has been performed to provide more insight into the interaction of the bending modes and its impact on the solder joint failures. This paper demonstrates the process of understanding use conditions, developing reliability tests, validating test results and driving industry standards.
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Yang, Chulho, Hitesh D. Vora, and Young B. Chang. "Application of Auxetic Polymeric Structures for Body Protection." In ASME 2016 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/smasis2016-9208.
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Negative Poisson’s ratio (NPR) materials, also known as auxetic materials, have many promising application areas. In recent years, various auxetic material structures have been designed and fabricated for diverse applications that utilized normal materials which follow Hooke’s law but still show the properties of negative Poisson’s ratios. In light of this, efforts are made to apply auxetic material structures to body protection pads that are comfortable to wear and effective in protecting body parts by reducing impact force and preventing injuries in high-risk individuals such as elderly people, industry workers, law enforcement and military personnel, and sport players. For those people, blunt impacts such as falls, bullets, and blast wave may reduce quality of life, increase the possibility of early death and generate an extremely high medical costs. Therefore, it is important to develop new body protectors that best combine each individual’s requirements of wearing comfort (flexible, light weight), ease of fitting (customized), ensured protection, and cost-effectiveness. The developed protection pad would be made from multilayer materials with an adaptive structure to achieve a unique multifunctional properties such as high hardness, impact toughness, light weight, excellent shock absorption, self-assembly suitable for the needs. Particularly, an integrated computational (finite element analysis) approach is used to investigate the effect of three material structures (honeycomb or flexin structure, re-entrant hexagonal cells or reflexin structure, and arrowhead structure) in combination with three polymeric materials (Polylactic acid (PLA) and two thermoplastic polyurethane (TPU) materials). Efforts are made to relate the individual and/or combined effect of auxetic structure and materials to the overall stiffness and shock-absorption performance of the body protection pads. Initially, parametric 3D CAD models of auxetic polymeric structures are developed. Later, key structural characteristics of protectors are evaluated through static analyses of FEA models. Impact/shock analyses are conducted to validate the results obtained from the static analyses. The mechanism for ideal input force distribution or shunting is suggested for designing protectors using various shapes, thicknesses, and materials of auxetic materials to reduce the risk of injury. The results show that the auxetic material can be considered as an effective material structure for body protection pads.
Reports on the topic "Shock Pad"
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Coile, Courtney, Maya Rossin-Slater, and Amanda Su. The Impact of Paid Family Leave on Families with Health Shocks. Cambridge, MA: National Bureau of Economic Research, December 2022. http://dx.doi.org/10.3386/w30739.
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Anand, Priyanka, Laura Dague, and Kathryn Wagner. The Role of Paid Family Leave in Labor Supply Responses to a Spouse’s Disability or Health Shock. Cambridge, MA: National Bureau of Economic Research, May 2021. http://dx.doi.org/10.3386/w28808.
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Otero-Cortés, Andrea, Ana María Tribín-Uribe, and Tatiana Mojica-Urueña. The Heterogeneous Labor Market Effects of the Venezuelan Exodus on Female Workers: Evidence from Colombia. Banco de la República, July 2022. http://dx.doi.org/10.32468/dtseru.311.
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We study the labor market effects of the Venezuelan migration shock on female labor market outcomes in Colombia using a Bartik-instrument approach.For our identification strategy we leverage regional variation from pull factors and time variation from push factors. Our findings show that in the labor market, female immigrants can act as substitutes or complements for native-born women depending on native women’s education level; immigrant workers are substitutes in the labor market for native-born low-educated women as they compete for similar jobs. Hence, the low-educated native women’s labor force participation decreases. At the same time, time spent doing unpaid care increases for low-educated native women, possibly further preventing the job search for this group. On the other hand, we find an increase in labor force participation of 1.6 p.p. for highly educated women with minors at home and a 1 p.p. higher likelihood of becoming entrepreneurs due to the migratory shock, which supports the complementary-skill hypothesis. Finally, we don’t find evidence that the migratory shock induced households to outsource more home-production as a means for high-educated women to spend more time at paid work.
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Slater, Rachel, and Daniel Longhurst. Social Assistance Systems in Crisis Situations: Resilient, Responsive and Sensitive? Institute of Development Studies (IDS), February 2022. http://dx.doi.org/10.19088/basic.2022.019.
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Evidence on what enables social assistance systems to deliver routinely, effectively and efficiently is limited in crisis situations. Shock-responsive social protection (SRSP) and adaptive social protection (ASP) have become popular in global and national development discourses. Yet, their operationalisation in protracted crises is narrow and less well understood. Regarding SRSP, focus has shifted towards how existing social protection programmes might be scaled and flexed in crisis situations. However, the focus seems fixed entirely on what makes social protection and humanitarian assistance responsive – to the detriment of understanding what makes those systems resilient and able to maintain business continuity in protracted crises. Little attention is paid to how to sustain delivery of existing programmes, on which millions of poor and vulnerable households depend.
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Slater, Rachel. Sustaining Existing Social Protection Programmes During Crises: What Do We Know? How Can We Know More? Institute of Development Studies, May 2022. http://dx.doi.org/10.19088/basic.2022.014.
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Research on social assistance in crisis situations has focused predominantly on how social assistance can flex in response to rapid-onset emergencies such as floods or hurricanes and to slower-onset shocks such as drought. This paper identifies a substantial knowledge gap – namely, our understanding of the ways in which existing, government-led programmes can be sustained during crises to ensure that households that were already poor and vulnerable before a crisis continue to be supported. The limited literature available focuses on climate- and natural environment-related shocks – far less attention is paid to other crises. Conflict-affected situations are a major gap, although there is an emerging body of evidence of the ways in which focus on adapting delivery mechanisms has allowed social assistance and other social protection programmes to be sustained throughout the Covid-19 pandemic. The paper concludes that a better understanding of when, where and how existing programmes can be sustained during situations of violent conflict will help to ensure that poor and vulnerable households can be supported – either through government programmes or by enabling robust diagnosis of when efforts to sustaining existing programmes will be inadequate and an additional, external responses are required.
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Valencia, Sandra C. WFP’s Contributions to Improving the Prospects for Peace in the Central American Dry Corridor: Spotlight on Climate Change. Stockholm International Peace Research Institute, November 2022. http://dx.doi.org/10.55163/aefi7913.
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This report explores the linkages between climate change, food security and conflict in the Central American Dry Corridor region. Specifically, the report analyses how climatic shocks and stresses affect food security and the risk of conflict in the Dry Corridor, through case studies of Guatemala and Honduras. In addition, the research analyses if, and how, the World Food Programme’s (WFP) Food for Assets programmes, which seek to increase resilience, are mitigating conflict risk, and WFP’s role in longer-term peacebuilding efforts against the backdrop of negative climate trends. The research was conducted in a selection of WFP’s intended beneficiary communities considered part of the Dry Corridor in the departments of Chiquimula and Zacapa in Guatemala and in the departments of La Paz and Santa Barbara in Honduras. Two theories of change are proposed for how WFP can improve the prospects for peace and reduce conflict sensitivity risks through its Food for Assets Resilience programming in the Dry Corridor: one related to land tenure and a second related to water governance. The research was part of a wider knowledge partnership between SIPRI and WFP. The partnership aimed to inform WFP’s potential contributions to improving the prospects for peace and how to address these through WFP’s programming.
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Droby, Samir, Michael Wisniewski, Ron Porat, and Dumitru Macarisin. Role of Reactive Oxygen Species (ROS) in Tritrophic Interactions in Postharvest Biocontrol Systems. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7594390.bard.
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To elucidate the role of ROS in the tri-trophic interactions in postharvest biocontrol systems a detailed molecular and biochemical investigation was undertaken. The application of the yeast biocontrol agent Metschnikowia fructicola, microarray analysis was performed on grapefruit surface wounds using an Affymetrix Citrus GeneChip. the data indicated that 1007 putative unigenes showed significant expression changes following wounding and yeast application relative to wounded controls. The expression of the genes encoding Respiratory burst oxidase (Rbo), mitogen-activated protein kinase (MAPK) and mitogen-activated protein kinase kinase (MAPKK), G-proteins, chitinase (CHI), phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and 4-coumarate-CoA ligase (4CL). In contrast, three genes, peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), were down-regulated in grapefruit peel tissue treated with yeast cells. The yeast antagonists, Metschnikowia fructicola (strain 277) and Candida oleophila (strain 182) generate relatively high levels of super oxide anion (O2−) following its interaction with wounded fruit surface. Using laser scanning confocal microscopy we observed that the application of M. fructicola and C. oleophila into citrus and apple fruit wounds correlated with an increase in H2O2 accumulation in host tissue. The present data, together with our earlier discovery of the importance of H₂O₂ production in the defense response of citrus flavedo to postharvest pathogens, indicate that the yeast-induced oxidative response in fruit exocarp may be associated with the ability of specific yeast species to serve as biocontrol agents for the management of postharvest diseases. Effect of ROS on yeast cells was also studied. Pretreatment of the yeast, Candida oleophila, with 5 mM H₂O₂ for 30 min (sublethal) increased yeast tolerance to subsequent lethal levels of oxidative stress (50 mM H₂O₂), high temperature (40 °C), and low pH (pH 4). Suppression subtractive hybridization analysis was used to identify genes expressed in yeast in response to sublethal oxidative stress. Transcript levels were confirmed using semi quantitative reverse transcription-PCR. Seven antioxidant genes were up regulated. Pretreatment of the yeast antagonist Candida oleophila with glycine betaine (GB) increases oxidative stress tolerance in the microenvironment of apple wounds. ROS production is greater when yeast antagonists used as biocontrol agents are applied in the wounds. Compared to untreated control yeast cells, GB-treated cells recovered from the oxidative stress environment of apple wounds exhibited less accumulation of ROS and lower levels of oxidative damage to cellular proteins and lipids. Additionally, GB-treated yeast exhibited greater biocontrol activity against Penicillium expansum and Botrytis cinerea, and faster growth in wounds of apple fruits compared to untreated yeast. The expression of major antioxidant genes, including peroxisomal catalase, peroxiredoxin TSA1, and glutathione peroxidase was elevated in the yeast by GB treatment. A mild heat shock (HS) pretreatment (30 min at 40 1C) improved the tolerance of M. fructicola to subsequent high temperature (45 1C, 20–30 min) and oxidative stress (0.4 mol-¹) hydrogen peroxide, 20–60 min). HS-treated yeast cells showed less accumulation of reactive oxygen species (ROS) than non-treated cells in response to both stresses. Additionally, HS-treated yeast exhibited significantly greater (P≥0.0001) biocontrol activity against Penicillium expansum and a significantly faster (Po0.0001) growth rate in wounds of apple fruits stored at 25 1C compared with the performance of untreated yeast cells. Transcription of a trehalose-6-phosphate synthase gene (TPS1) was up regulated in response to HS and trehalose content also increased.
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Dudareva, Natalia, Alexander Vainstein, Eran Pichersky, and David Weiss. Integrating biochemical and genomic approaches to elucidate C6-C2 volatile production: improvement of floral scent and fruit aroma. United States Department of Agriculture, September 2007. http://dx.doi.org/10.32747/2007.7696514.bard.
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The specific objectives of approved proposal include to: 1. Elucidate the C6-C2 biochemical pathways leading to the biosynthesis of phenylacetaldehyde, phenylethyl alcohol and phenylethyl acetate in floral tissues of ornamentally important plants, pefunia and roses. 2. Isolate and characterrze genes responsible for the production of these C6-C2 compounds and those involved in the regulation of the pathway using genomic and transcriptomic tools. 3. Determine whether altering the expression of key genes of this pathway can result in changing the aroma characteristics of flowers. Aldehydes are intermediates in a variety of biochemical pathways including those involved in the metabolism of carbohydrates, vitamins, steroids, amino acids, benzylisoquinoline alkaloids, hormones, and lipids. In plants they are also synthesized in response to environmental stresses such as salinity, cold, and heat shock or as flavors and aromas in fruits and flowers. Phenylacetaldehyde along with 2-phenylethanol and its acetate ester, are important scent compounds in numerous flowers, including petunias and roses. However, little is known about the biosynthesis of these volatile compounds in plants. We have shown that the formation PHA and 2-phenylethanol from Phe does not occur via trans-cinnamic acid and instead competes with the key enzyme of phenypropanoid metabolism Pheammonia-lyase (PAL) for Phe utilization. Using functional genomic approach and comparative gene expression profiling, we have isolated and characterized a novel enzyme from petunia and rose flowers that catalyzes the formation of the Ca-Czcompound phenylacetaldehyde (PHA) from L-phenylalanine (Phe) by the removal of both the carboxyl and amino groups. This enzyme, designated as phenylacetaldehyde synthases (PAAS), is a bifunctional enzyme that catalyzes the unprecedented efficient coupling of phenylalanine decarboxylation to oxidation, generating phenylacetaldehyde, CO2, ammonia, and hydrogen peroxide in stoichiometric amounts. Down-regulation of PAAS expression via RNA interference-based (RNAi) technology in petunia resulted in no PHA emission when compared with controls. These plants also produced no 2-phenylethanol, supporting our conclusion that PHA is a precursor of 2-phenylethanol. To understand the regulation of scent formation in plants we have also generated transgenic petunia and tobacco plants expressing the rose alcohol acetyltransferase (RhAAT) gene under the control of a CaMV-35S promoter. Although the preferred substrate of RhAAT in vitro is geraniol, in transgenic petunia flowers, it used phenylethyl alcohol and benzyl alcohol to produce the corresponding acetate esters, not generated by control flowers. These results strongly point to the dependence of volatile production on substrate availability. Analysis of the diurnal regulation of scent production in rose flowers revealed that although the daily emission of most scent compounds is synchronized, various independently evolved mechanisms control the production, accumulation and release of different volatiles. This research resulted in a fundamental discovery of biochemical pathway, enzymes and genes involved in biosynthesis of C6-C2s compounds, and provided the knowledge for future engineering plants for improved scent quality.
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Lichter, Amnon, Joseph L. Smilanick, Dennis A. Margosan, and Susan Lurie. Ethanol for postharvest decay control of table grapes: application and mode of action. United States Department of Agriculture, July 2005. http://dx.doi.org/10.32747/2005.7587217.bard.
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Original objectives: Dipping of table grapes in ethanol was determined to be an effective measure to control postharvest gray mold infection caused by Botrytis cinerea. Our objectives were to study the effects of ethanol on B.cinerea and table grapes and to conduct research that will facilitate the implementation of this treatment. Background: Botrytis cinerea is known as the major pathogen of table grapes in cold storage. To date, the only commercial technology to control it relied on sulfur dioxide (SO₂) implemented by either fumigation of storage facilities or from slow release generator pads which are positioned directly over the fruits. This treatment is very effective but it has several drawbacks such as aftertaste, bleaching and hypersensitivity to humans which took it out of the GRAS list of compounds and warranted further seek for alternatives. Prior to this research ethanol was shown to control several pathogens in different commodities including table grapes and B. cinerea. Hence it seemed to be a simple and promising technology which could offer a true alternative for storage of table grapes. Further research was however required to answer some practical and theoretical questions which remained unanswered. Major conclusions, solutions, achievements: In this research project we have shown convincingly that 30% ethanol is sufficient to prevent germination of B. cinerea and kill the spores. In a comparative study it was shown that Alternaria alternata is also rather sensitive but Rhizopus stolonifer and Aspergillus niger are less sensitive to ethanol. Consequently, ethanol protected the grapes from decay but did not have a significant effect on occurrence of mycotoxigenic Aspergillus species which are present on the surface of the berry. B. cinerea responded to ethanol or heat treatments by inducing sporulation and transient expression of the heat shock protein HSP104. Similar responses were not detected in grape berries. It was also shown that application of ethanol to berries did not induce subsequent resistance and actually the berries were slightly more susceptible to infection. The heat dose required to kill the spores was determined and it was proven that a combination of heat and ethanol allowed reduction of both the ethanol and heat dose. Ethanol and heat did not reduce the amount or appearance of the wax layers which are an essential component of the external protection of the berry. The ethanol and acetaldehyde content increased after treatment and during storage but the content was much lower than the natural ethanol content in other fruits. The efficacy of ethanol applied before harvest was similar to that of the biological control agent, Metschnikowia fructicola, Finally, the performance of ethanol could be improved synergistically by packaging the bunches in modified atmosphere films which prevent the accumulation of free water. Implications, both scientific and agricultural: It was shown that the major mode of action of ethanol is mediated by its lethal effect on fungal inoculum. Because ethanol acts mainly on the cell membranes, it was possible to enhance its effect by lowering the concentration and elevating the temperature of the treatment. Another important development was the continuous protection of the treated bunches by modified atmosphere that can solve the problem of secondary or internal infection. From the practical standpoint, a variety of means were offered to enhance the effect of the treatment and to offer a viable alternative to SO2 which could be instantly adopted by the industry with a special benefit to growers of organic grapes.
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Technology and Tax: Adoption and Impacts of E-services in Rwanda. Institute of Development Studies, January 2023. http://dx.doi.org/10.19088/ictd.2023.001.
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Many low-income countries are increasingly digitising various tax services, usually motivated by efforts to increase efficiency and transparency and reduce the burden of compliance for taxpayers. However, where awareness and adoption are suboptimal, tax e services may produce only partial benefits. In this paper, we examine the adoption of tax e-services in Rwanda, a low-income country which has invested significant resources in digitalising government service delivery and made tax e-services mandatory from 2015. Using a combination of panel survey and tax administrative data, we study the drivers and impacts of e-services awareness and adoption. We find evidence that, before the pandemic, female and less educated taxpayers, with less sophisticated businesses, were left behind in technology adoption, even where e-services were the only option for taxpayers. Exploiting the outbreak of COVID-19 during our data collection, we also study shifts precipitated by a shock that normalised digital transactions. Take-up of e-services is remarkable two years after the pandemic, but still not universal. For those not using the e services the same challenges in access persist – indicating the potential for more targeted policy interventions. Interestingly, technology adoption is not strongly related with filing behaviour, and we study the reasons why non-filers report using the tools and, on the contrary, why active filers report they do not. Also, we do not find any significant impact of e-services adoption on perceived fairness of the tax system and overall willingness to pay, which we hypothesised benefit from e-services. Finally, using evidence from qualitative interviews, we highlight practical challenges in using e-services, such as connectivity problems and slow systems, which undermine the potential benefits.