On ballistic parameters of less lethal projectiles influencing the severity of thoracic blunt impacts

The development and safety certification of less lethal projectiles require an understanding of the influence of projectile parameters on projectile–chest interaction and on the resulting terminal effect. Several energy-based criteria have been developed for chest injury assessment. Many studies consider kinetic energy (KE) or energy density as the only projectile parameter influencing terminal effect. In a common KE range (100–160 J), analysis of the firing tests of two 40 mm projectiles of different masses on animal surrogates has been made in order to investigate the severity of the injuries in the thoracic region. Experimental results have shown that KE and calibre are not sufficient to discriminate between the two projectiles as regards their injury potential. Parameters, such as momentum, shape and impedance, influence the projectile–chest interaction and terminal effect. A simplified finite element model of projectile–structure interaction confirms the experimental tendencies. Within the range of ballistic parameters used, it has been demonstrated that maximum thoracic deflection is a useful parameter to predict the skeletal level of injury, and it largely depends on the projectile pre-impact momentum. However, numerical simulations show that these results are merely valid for the experimental conditions used and cannot be generalised. Nevertheless, the transmitted impulse seems to be a more general factor governing the thorax deflection.     

Ultrastructure,biogenesis, and functions of extrusive organelles in selected non-ciliate protists

Summary The ultrastructural features, biogenesis and functions of several selected protist extrusive organelles are discussed. Most of the review focuses on some common extrusive organelles that were not considered by Hausmann and several types which have been described since that review of 16 years ago. For convenience, extrusomes are categorized as projectile or mucocyst extrusomes. The projectile extrusomes are further subdivided into non-penetrating and cell penetrating extrusomes. This review is restricted to projectile extrusomes such as ejectisomes, the microsporidian invasion apparatus, and the gun cell of oomycetes. Mucocysts include the apicomplexan rhoptries, the K₂ bodies of oomycetes, and the spermatial vesicles and adhesive vesicles of red algae. The possible phylogenetic importance of some extrusive organelles is briefly considered.     

Throwing in the Middle and Upper Paleolithic: inferences from an analysis of humeral retroversion

When in evolutionary history did long-range projectile weapons become an important component of hunting toolkits? The archeological evidence for the development of projectile weaponry is complex and generally indirect, and has led to different conclusions about the origin and spread of this technology. Lithic evidence from the Middle Stone Age (MSA) has led some researchers to suggest that true long- range projectile weaponry developed in Africa perhaps as early as 80,000 years ago, and was part of the subsistence toolkit carried by modern humans who expanded out of Africa after 50,000 years ago. Alternatively, temporal patterns in the morphology of pointed lithics has led others to posit an independent, convergent origin of projectile weaponry in Africa, the Near East, and Europe during the interval between 50,000-40,000 years ago. By either scenario, projectile weapons would not have been a component of the hunting arsenal of Neandertals, but may have been in use by European early modern humans and thus, projectile technology may have entered into the competitive dynamics that existed between these two groups. The origins of projectile weapons can be addressed, in part, through analyses of the skeletal remains of the prehistoric humans who made and used them. Habitual behavior patterns—including those related to the production and use of technology—can be imprinted on the skeleton through both genetic and epigenetic pathways. Recent studies in the field of sports medicine indicate that individuals who engage in habitual throwing have increased humeral retroversion angles in their throwing arms and a greater degree of bilateral asymmetry in retroversion angles than do non-throwers. This contribution investigates humeral torsion through analysis of the retroversion angle in samples of Eurasian Neandertals, European early modern humans of the middle and late Upper Paleolithic, and comparative samples of recent humans. This analysis was conducted under the assumption that if throwing-based projectile weaponry was used by early modern Europeans but not Neandertals, Upper Paleolithic samples should be similar to recent human groups engaged in habitual throwing in the degree of humeral retroversion in the dominant limb and in bilateral asymmetry in this feature. Neandertals on the other hand, would not be expected to show marked asymmetry in humeral retroversion. Consistent with other studies, Neandertals exhibit increased retroversion angles (decreased humeral torsion or a more posteriorly oriented humeral head) relative to most modern human samples, although this appears more likely related to body form and overall activity levels than to habitual throwing. Although Neandertals with bilaterally preserved humeri sufficient for measurement are rare (consisting of only two males and one female), levels of bilateral asymmetry in humeral retroversion are low, suggesting a lack of regular throwing. While patterning across fossil and comparative samples in levels of humeral retroversion was not clear cut, males of both the middle and late Upper Paleolithic demonstrate a high level of bilateral asymmetry, comparable to or in excess of that seen in samples of throwing athletes. This may indicate habitual use of throwing-based projectile weaponry by middle Upper Paleolithic times. Small sample sizes and relatively great variance in the fossil samples makes these results, however, suggestive rather than conclusive.     

射击类带尖石制品使用微痕动态形成过程的实验研究

石镞主要是旧石器时代晚期出现的一种投射类复合武器的尖端,其使用方式一直为学术界所关注。本文以山西吉县柿子滩遗址环境背景和石器原料为参照,通过微痕实验,探讨射击类带尖石制品重复使用过程中微痕的动态形成过程。作者对21件实验标本分阶段累计射击337次,微痕观察121次。分析结果显示,射击类带尖石制品的重复使用情况可以通过微痕进行佐证。形态变化过程表明,尖端变化较为显著,指示应以动态思维考量出土石镞形态及其暗示的人类行为;测量数据显示,尖端及侧刃较为锋利、长度适中的标本,射击效果更好,存在多次使用的可能;微痕分析指示,若尖端产生层叠大中型折断式、阶梯式疤痕,装柄部位产生连续小型折断式或羽翼式疤痕,部分出现磨圆与光泽时可以考虑重复使用的可能。本项研究为揭示石镞背后所蕴含的狩猎策略、生计方式等人类行为信息提供了数据参考。     

Timing accuracy in human throwing

This study examines the precision required in the timing of muscle activations and projectile release to hit a target of 20 cm in diameter oriented horizontally either 6 or 8 m away. Over-arm throws, constrained to the sagittal plane, were simulated using a muscle-actuated, two-segment model representing the forearm and hand plus projectile. The parameters defining the modeled muscles and the anthropometry were specific to two male subjects. An objective function specified that throws must be both fast and accurate. Once an optimal solution had been found, the sensitivity of these timings was investigated. The times of activation or release were changed and the simulation model re-run with the new timings, and it was determined whether the projectile would still have struck the target. For one set of simulations, to hit the target at 8 m, the optimal throw was achieved with a time delay between the onset of wrist activation and elbow extensor activation [Proximal-distal (PD) delay] of 49 ms and a release time of 83.4 ms. At this optimal point in the solution space, the launch window was 1.2 ms (assuming the original PD delay). The launch window was the time available within which the projectile must be released and still strike the target. The window during which the wrist flexors could be activated was 10. 41 ms (assuming the projectile was released at the pre-planned optimal time). The control scheme which required the least timing precision had a PD delay of 56 ms and a release time of 89.4 ms. Errors in timing could occur in activation and release simultaneously under this scheme, the timing windows were 4 ms in PD delay and 2.4 ms in release. Similar results were found for a second set of simulations. These simulations revealed the precise timings required in muscle activations and release required for fast accurate throws.     

The Scoggin Site: a Study in Mckean Typology

Abstract

The Scoggin Site, an Early Middle Period Bison kill in south-central Wyoming, yielded two distinct stylized projectile point varieties from the one bone layer present. This single component affords optimum opportunity to study the two varieties of points in one context. The technology for the projectile point assemblage is described, and literature concerning the deep side-notched Early Middle Period or Archaic age points from the Northwestern Plains and the northern Great Basin is discussed.

In order to discover if the deep side-notched projectile points from Scoggin (reminiscent of much later projectile point types) were indeed part of the McKean classification, their dimensions were compared to those of the indented base McKean lanceolate projectile points from the same site. The measurements overlap or can be otherwise explained for both lanceolate and side-notched forms. The Statistical Package for the Social Sciences (SPSS) was used to demonstrate that the two types of points are quite homogeneous.

The question as to why the points differ stylistically has several possible answers. For example, the two types may represent interacting but identifiable ethnic groups, or the numerical superiority of the side-notched point may reflect hafting superiority. At any rate, the deep side-notched point is an integral part of the Early Middle Period and can be classified as McKean.     

The biomechanics of an overarm throwing task: a simulation model examination of optimal timing of muscle activations.

A series of overarm throws, constrained to the parasagittal plane, were simulated using a muscle model actuated two-segment model representing the forearm and hand plus projectile. The parameters defining the modeled muscles and the anthropometry of the two-segment models were specific to the two young male subjects. All simulations commenced from a position of full elbow flexion and full wrist extension. The study was designed to elucidate the optimal inter-muscular coordination strategies for throwing projectiles to achieve maximum range, as well as maximum projectile kinetic energy for a variety of projectile masses. A proximal to distal (PD) sequence of muscle activations was seen in many of the simulated throws but not all. Under certain conditions moment reversal produced a longer throw and greater projectile energy, and deactivation of the muscles resulted in increased projectile energy. Therefore, simple timing of muscle activation does not fully describe the patterns of muscle recruitment which can produce optimal throws. The models of the two subjects required different timings of muscle activations, and for some of the tasks used different coordination patterns. Optimal strategies were found to vary with the mass of the projectile, the anthropometry and the muscle characteristics of the subjects modeled. The tasks examined were relatively simple, but basic rules for coordinating these tasks were not evident.     

Evaluation of different projectiles in matched experimental eye impact simulations

Eye trauma results in 30,000 cases of blindness each year in the United States and is the second leading cause of monocular visual impairment. Eye injury is caused by a wide variety of projectile impacts and loading scenarios with common sources of trauma being motor vehicle crashes, military operations, and sporting impacts. For the current study, 79 experimental eye impact tests in literature were computationally modeled to analyze global and localized responses of the eye to a variety of blunt projectile impacts. Simulations were run with eight different projectiles (airsoft pellets, baseball, air gun pellets commonly known as BBs, blunt impactor, paintball, aluminum, foam, and plastic rods) to characterize effects of the projectile size, mass, geometry, material properties, and velocity on eye response. This study presents a matched comparison of experimental test results and computational model outputs including stress, energy, and pressure used to evaluate risk of eye injury. In general, the computational results agreed with the experimental results. A receiver operating characteristic curve analysis was used to establish the stress and pressure thresholds that best discriminated for globe rupture in the matched experimental tests. Globe rupture is predicted by the computational simulations when the corneoscleral stress exceeds 17.21 MPa or the vitreous pressure exceeds 1.01 MPa. Peak stresses were located at the apex of the cornea, the limbus, or the equator depending on the type of projectile impacting the eye. A multivariate correlation analysis revealed that area-normalized kinetic energy was the best single predictor of peak stress and pressure. Additional incorporation of a relative size parameter that relates the projectile area to the area of the eye reduced stress response variability and may be of importance in eye injury prediction. The modeling efforts shed light on the injury response of the eye when subjected to a variety of blunt projectile impacts and further validate the eye model's ability to predict globe rupture. Results of this study are relevant to the design and regulation of safety systems and equipment to protect against eye injury.     

Rummells-Maske: A Clovis Find-Spot in Iowa

Abstract

The first controlled excavation of a Clovis site in Iowa revealed a concentration of complete and fragmentary Clovis Fluted projectile points. The site, in eastern Iowa, is interpreted as a projectile point cache destroyed by agricultural implements. Measurements and photographs are provided to facilitate the comparison of the collection with assemblages from other states.     

The Stone Tool Technology of Ishi and the Yana of North Central California: Inferences for Hunter-Gatherer Cultural Identity in Historic California

Recent developments in the Ishi "saga" have generated tremendous media attention, as well as opinions offered by a number of academics. Few of these opinion pieces have been based on much empirical data or historical evidence. An examination of Ishi's stone tool technology, particularly projectile point production, his physical morphology, and regional ethnohistoric oral history suggest a very different persona and cultural history for Ishi than previously reported. Rarely in archaeological or ethnographic contexts do we have an observable relationship between ethnicity, acculturation, and prehistoric technology. In the case of Ishi's short five-year stay at the Museum of Anthropology, University of California, all of these important elements converge. The data analysis here and resulting inferences have definite ramifications for the current debate surrounding projectile point style and cultural identity, as well as the long term effects of marginalization by invading and hostile non-Yana societies. [Ishi, projectile point technology, style and information, Native California, cultural identity]     

An experimental study in bio-ballistics: Femoral fractures produced by projectiles—II Shaft impacts

To determine the response of human cortical bone to projectile impact, 364 projectile impact tests were conducted on the shafts of embalmed human femurs. Chrome steel spherical projectiles in two diameters, 0·250 and 0·406 in., were employed to differentiate the effects of projectiles of varied sizes and masses in impacts at the same velocity. It was found that the larger projectiles expended significantly more energy in fracturing a femur than the smaller projectiles did at an identical impact velocity. Also, when impacts in which larger and smaller spheres possessed identical kinetic energies were compared, it was found that the larger spheres still expended more energy in fracturing the femur. Finally, it was clearly demonstrated by these experiments that impacts to cortical bone of the femoral shaft by either size projectile caused greater energy expenditure than impacts to the distal end of the femur, which is composed almost entirely of cancellous bone.     

Energy loss of hydrogen- and helium-ion beams in DNA: calculations based on a realistic energy-loss function of the target

We have calculated the electronic energy loss of proton and α-particle beams in dry DNA using the dielectric formalism. The electronic response of DNA is described by the MELF-GOS model, in which the outer electron excitations of the target are accounted for by a linear combination of Mermin-type energy-loss functions that accurately matches the available experimental data for DNA obtained from optical measurements, whereas the inner-shell electron excitations are modeled by the generalized oscillator strengths of the constituent atoms. Using this procedure we have calculated the stopping power and the energy-loss straggling of DNA for hydrogen- and helium-ion beams at incident energies ranging from 10 keV/nucleon to 10 MeV/nucleon. The mean excitation energy of dry DNA is found to be I = 81.5 eV. Our present results are compared with available calculations for liquid water showing noticeable differences between these important biological materials. We have also evaluated the electron excitation probability of DNA as a function of the transferred energy by the swift projectile as well as the average energy of the target electronic excitations as a function of the projectile energy. Our results show that projectiles with energy ?100 keV/nucleon (i.e., around the stopping-power maximum) are more suitable for producing low-energy secondary electrons in DNA, which could be very effective for the biological damage of malignant cells.     

An Alternative View of Some Southern Plains Archaic Stage Characteristics

Abstract

It is argued that Hammatt’s 1976 review of the Southern Plains Archaic Stage is in part not well reasoned or well supported. His contention that projectile point styles are not reliable as indicators of Archaic sites, while Clear Fork gouges are, is unsupportable and logically inconsistent based on the data he used. Other attributes used by Hammatt to define Archaic components are also discussed. Hammatt views the study of subsistence patterns (adaptation) rather than projectile points, as a more meaningful way to identify Archaic sites. This is a welcome argument and goal     

Large Springs And Early American Indians

Abstract

Several major collections of early lanceolate projectile points have been made on the Edwards Plateau and along the Balcones Fault. Each of these sites is located beside a spring emerging from a “Hill Country” aquifer. One of these is currently being excavated. The relationship is examined along with the concept of Paleo-Indian typology.     

月季组织培养和遗传转化体系的研究进展

月季通过器官和体细胞胚发生途径都可以获得再生植株,在遗传转化中主要是利用体细胞胚作为转化受体。目前,利用农杆菌介导法和基因枪法已成功将外源基因如报告基因、抗病基因和改变花色的基因等导入月季基因组中。本文对近年来月季组织培养和转基因研究进展进行了综述,为建立月季高效遗传转化体系奠定了理论基础。     

Prehistoric Artifacts From The Little Nemaha River Drainage,Otoe County,Nebraska

Abstract

The article describes certain stream deposited pottery sherds and projectile points found in south eastern Nebraska. Some of the sherds are attributable to the Sterns Creek complex and to the more general category of the Early Ceramic Period on the Central Plains. Most of the projectile points suggest preceramic affinities including the Logan Creek and Angostura complexes.     

Visualization of High Speed Liquid Jet Impaction on a Moving Surface

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds between 0 and 25 m/sec) and a spinning disk device (for examining surface speeds between 15 and 100 m/sec). The air cannon linear traverse is a pneumatic energy-powered system that is designed to accelerate a metal rail surface mounted on top of a wooden projectile. A pressurized cylinder fitted with a solenoid valve rapidly releases pressurized air into the barrel, forcing the projectile down the cannon barrel. The projectile travels beneath a spray nozzle, which impinges a liquid jet onto its metal upper surface, and the projectile then hits a stopping mechanism. A camera records the jet impingement, and a pressure transducer records the spray nozzle backpressure. The spinning disk set-up consists of a steel disk that reaches speeds of 500 to 3,000 rpm via a variable frequency drive (VFD) motor. A spray system similar to that of the air cannon generates a liquid jet that impinges onto the spinning disc, and cameras placed at several optical access points record the jet impingement. Video recordings of jet impingement processes are recorded and examined to determine whether the outcome of impingement is splash, splatter, or deposition. The apparatuses are the first that involve the high speed impingement of low-Reynolds-number liquid jets on high speed moving surfaces. In addition to its rail industry applications, the described technique may be used for technical and industrial purposes such as steelmaking and may be relevant to high-speed 3D printing.     

Experimental model for civilian ballistic brain injury biomechanics quantification

Biomechanical quantification of projectile penetration using experimental head models can enhance the understanding of civilian ballistic brain injury and advance treatment. Two of the most commonly used handgun projectiles (25-cal, 275 m/s and 9 mm, 395 m/s) were discharged to spherical head models with gelatin and Sylgard simulants. Four ballistic pressure transducers recorded temporal pressure distributions at 308kHz, and temporal cavity dynamics were captured at 20,000 frames/second (fps) using high-speed digital video images. Pressures ranged from 644.6 to -92.8 kPa. Entry pressures in gelatin models were higher than exit pressures, whereas in Sylgard models entry pressures were lower or equivalent to exit pressures. Gelatin responded with brittle-type failure, while Sylgard demonstrated a ductile pattern through formation of micro-bubbles along projectile path. Temporary cavities in Sylgard models were 1.5-2x larger than gelatin models. Pressures in Sylgard models were more sensitive to projectile velocity and diameter increase, indicating Sylgard was more rate sensitive than gelatin. Based on failure patterns and brain tissue rate-sensitive characteristics, Sylgard was found to be an appropriate simulant. Compared with spherical projectile data, full-metal jacket (FMJ) projectiles produced different temporary cavity and pressures, demonstrating shape effects. Models using Sylgard gel and FMJ projectiles are appropriate to enhance understanding and mechanisms of ballistic brain injury.     

Trauma among early Californians

The incidence and distribution of trauma is examined in a large number of individuals from many burial sites in California. The material represents part of an on-going curational effort at the Lowie Museum of Anthropology. Trauma is confined to fractures, dislocations, and projectile wounds for the purposes of this study. Only antemortem fractures are considered. The findings suggest that most fracture were due to accidents, though several parry fractures are present. The functional results of healing do not warrant any conclusions as to the efficacy of treatment or lack thereof. Several projectile wounds are seen, some with evidence of healing. Presented in part at the 55th annual meeting of the American Association of Physical Anthropologists, Albuquerque, New Mexico, April 1986.     

Social Complexity and the Bow in the Eastern Woodlands

Bingham and Souza 1 have presented an evolutionary theory that specifies a causal relationship between the advent of powerful projectile weapons such as the bow and radical rearrangements in social relations and histories. They propose that the acquisition of weapons that permitted humans to kill at ever‐increasing distances provided the coercive means to suppress conflicts of interest among nonkin, self‐interested individuals in social groups, thus paving the way for greater social complexity. An unprecedented reduction in projectile point size identifies the arrival of the bow ca. A.D. 300 in the Eastern Woodlands of North America, which initiated a causal chain of cultural changes. In the Midwest, the bow, combined with food production, precipitated the decline of Hopewell by conferring household autonomy and dispersal, which at first suppressed social complexity, but later created conditions favorable to maize intensification. In the lower Southeast, where food production was unimportant, populations aggregated at concentrated wild‐food sources, and the bow did not confer household autonomy. The relationship between the bow and social complexity varied under different environmental, social, and historical conditions.