Working toward exposure thresholds for blast-induced traumatic brain injury: thoracic and acceleration mechanisms

Research in blast-induced lung injury resulted in exposure thresholds that are useful in understanding and protecting humans from such injury. Because traumatic brain injury (TBI) due to blast exposure has become a prominent medical and military problem, similar thresholds should be identified that can put available research results in context and guide future research toward protecting warfighters as well as diagnosis and treatment. At least three mechanical mechanisms by which the blast wave may result in brain injury have been proposed - a thoracic mechanism, head acceleration and direct cranial transmission. These mechanisms need not be mutually exclusive. In this study, likely regions of interest for the first two mechanisms based on blast characteristics (positive pulse duration and peak effective overpressure) are developed using available data from blast experiments and related studies, including behind-armor blunt trauma and ballistic pressure wave studies. These related studies are appropriate to include because blast-like pressure waves are produced that result in neurological effects like those caused by blast. Results suggest that injury thresholds for each mechanism are dependent on blast conditions, and that under some conditions, more than one mechanism may contribute. There is a subset of blast conditions likely to result in TBI due to head acceleration and/or a thoracic mechanism without concomitant lung injury. These results can be used to guide experimental designs and compare additional data as they become available. Additional data are needed before actual probabilities or severity of TBI for a given exposure can be described.Comment: 11 page

Blast Shock Wave Mitigation Using the Hydraulic Energy Redirection and Release Technology

A hydraulic energy redirection and release technology has been developed for mitigating the effects of blast shock waves on protected objects. The technology employs a liquid-filled plastic tubing as a blast overpressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy in the plastic tubings. The hydraulic energy is redirected through the plastic tubings to the openings at the lower ends, and then is quickly released with the liquid flowing out through the openings. The samples of the specifically designed body armor in which the liquid-filled plastic tubings were installed vertically as the outer layer of the body armor were tested. The blast test results demonstrated that blast overpressure behind the body armor samples was remarkably reduced by 97% in 0.2 msec after the liquid flowed out of its appropriate volume through the openings. The results also suggested that a volumetric liquid surge might be created when kinetic energy of blast shock wave was transferred into hydraulic energy to cause a rapid physical movement or displacement of the liquid. The volumetric liquid surge has a strong destructive power, and can cause a noncontact, remote injury in humans (such as blast-induced traumatic brain injury and post-traumatic stress disorder) if it is created in cardiovascular system. The hydraulic energy redirection and release technology can successfully mitigate blast shock waves from the outer surface of the body armor. It should be further explored as an innovative approach to effectively protect against blast threats to civilian and military personnel

The Hunt in Romance and the Hunt as Romance

Winthrop Wetherbee, Andrew Galloway, Masha RaskolnikovThis dissertation examines the English and French late medieval hunting manuals, in particular Gaston Phebus' Livre de chasse and Edward of Norwich's Master of Game. It explores their relationships with various literary and nonliterary texts, as well as their roles in the late medieval imagination, aristocratic self-image, and social economy. The medieval aristocracy used hunting as a way to imitate the heroes of chivalric romance, whose main pastimes were courtly love, arms, and the chase. It argues that manuals were, despite appearances, works of popular and imagination-stimulating literature into which moral or practical instruction was incorporated, rather than purely didactic texts. The first three chapters compare the manuals' content, style, authorial intent, and reader reception with those of the chivalric romances. Both genres are concerned with the interlaced adventures of superlative but generic characters. Furthermore, both genres are popular, insofar as they are written for profit and accessible to sophisticated and unsophisticated readers alike. The following four chapters examine the relationships between hunting, love, and military practices and ethics, as well as those between their respective didactic literatures. Hunters, dogs, and animals occupied a sort of interspecific social hierarchy, and the more noble individuals were expected to adhere to a code of behavior similar to the chivalric code. Military and amatory manuals, like hunting manuals, are texts that encourage imagination and role-playing and utilize the characters and narratives of chivalric romance. The hunting manual is a kind of arms manual that explains how to make war against animals; but it is also a sort of anti-love manual that teaches the hunter how to avoid feminine wiles. The final chapter documents a wide-ranging literary motif ("the generic literary hunt") that informs the structure and content of a large number of medieval works, from the most primitive hunting manuals to Sir Gawain and the Green Knight. The concluding chapter explores the evolution and popularity of the English printed hunting manuals from the fifteenth through the seventeenth centuries. The new manuals appealed to the social aspirations of an up-and-coming urban bourgeoisie, even as the European forests and their animals were disappearing

2005 Simulation of the collapse of an underwater explosion bubble under a circular plate

Abstract. A two-fluid, computational fluid dynamics study of the phenomena of bubble collapse under a submersed flat plate has been performed. In order to handle the rapidly changing bubble-water interface accurately, second order upwind differencing is used in calculating the advection term. Good agreement with experimental data is obtained for the pressure distribution on the plate. The computational results provide insight into the phenomenology of the jet impact, the formation of a radial hydraulic jump, and the complex interaction of that hydraulic jump with the collapsing toroidal bubble

Simulation of the Collapse of an Underwater Explosion Bubble under a Circular Plate

A two-fluid, computational fluid dynamics study of the phenomena of bubble collapse under a submersed flat plate has been performed. In order to handle the rapidly changing bubble-water interface accurately, second order upwind differencing is used in calculating the advection term. Good agreement with experimental data is obtained for the pressure distribution on the plate. The computational results provide insight into the phenomenology of the jet impact, the formation of a radial hydraulic jump, and the complex interaction of that hydraulic jump with the collapsing toroidal bubble