高原枪弹与破片飞行速度特点的实验研究

目的 了解枪弹与破片在高原的飞行速度特点,为高原战伤救治提供弹道学参数。方法 在海拔3658m的高原,分别采用弹道枪和军用步枪发射2种制式枪弹和3种不同形状的破片,以HWB-型红外线测速装置测定投射物在射距10m和20m的飞行速度,并以在平原地区(海拔351．5m)完成的同样实验作为对照。结果 高原枪弹与破片速度比平原快。射距20m,5．56mm弹和7、62mm弹其速度分别增加41．55m／s和40．89m／s;1．03g钢珠、0、44g圆柱、0．37g三角破片其速度分别增加94．65m／s、224．28m／s和263．38m／s。结论 高原投射物飞行速度较平原快,主要与高原空气密度稀薄、飞行阻力小有关。     

高原破片伤的创伤弹道特点

目的 了解高原球形和三角形破片分别击中猪后肢软组织的创伤弹道学特点。方法 在高原和平原,以53式滑膛枪分别发射1．03g钢球（射距20m）和0.37g三角形破片（射距10m）,射击猪（15-25kg）后肢肌肉丰满处,避免伤及股骨及大血管,测定投射物初速和终点速度。伤后6小时测量伤道出、入口面积以及琥珀酸脱氢酶、ATP酶活性测定、永久伤道容积;切取距伤道壁0．5cm、1．5cm处肌组织进行显微病理观察;按照“4C”法判定伤道失活组织后行手术清创,测定切除坏死组织量。按照前述生物实验的致伤方法,分别在高原和平原射击密度与猪肌肉组织相似的肥皂块,观察空腔大小。结果高原破片终点速度较平原快,高原组伤道的出入口面积、伤道容积、伤道长度比值、切除坏死组织以及破碎肌组织的比例均大于平原组,高原球形和三角形破片伤组伤道肌纤维断裂和变性的程度均较平原组重,肌组织琥珀酸脱氢酶和ATP酶的活性下降,分别为平原组的26．86％和55、77％。高原射击肥皂空腔容积大于平原。结论高原破片伤的损伤程度较平原重,这与高原空气密度低,破片飞行阻力小,破片飞行速度较平原快,击中组织的瞬时空腔大等有关。     

火器伤清创药物疗效评估模型的建立与分析

目的 建立一种用于火器伤药物清创疗效评估的动物模型.方法 兔、羊各4只分别为A、B组,猪8只,随机平均分为C、D组.采用"五三"式滑膛枪发射球形破片(枪口速度约850m/s,质量0.375g)致伤A、B、C组动物后肢软组织,相同方法发射圆柱形破片(枪口速度约950m/s,质量0.87g)致伤D组动物,观察局部伤情,进行...     

第六届国际创伤弹道学会议论文综述

第六届国际创伤弹道学会议于1988年11月1～4日在重庆三医大野战外科研究所召开,11个国家的150名代表参加了会议,报告和展出了论文131篇。 一、创伤弹道学的含义 瑞典Berlin建议扩大其内涵,不仅限于投射物在体内的运动规律,而且要包括相应的生物学改变。 二、杀伤标准 西德Sellier认为,杀伤标准(Gas-uahy Critereon)是指弹头或破片使人员不能战斗的能量。各种枪弹和破片造成杀伤的能量是不同的,因此各国的杀伤标准也不可能一致。 三、新的理论和技术 (1)相似理论(Similaritytheory):在着速相同的条件下,钢球穿透明胶的深度与其直径之比是恒定的。利用这一相似原理,可节省实验中所需的人力物力。(2)灰色系统理论(grey sys-tem theory):李天升等应用此理论将破片参数(如着速、质量、伤道长度等按其主要性和相关性排列,确定影响致伤效果的主要因素,忽略次要因素,为建立     

三倍频Nd:YAG激光器不同扫描速度对猪脱细胞真皮基质微孔孔径的影响

目的 探讨三倍频Nd:YAG激光器不同扫描速度对猪脱细胞真皮基质微孔孔径的影响.方法 在输出功率、频率等参数固定的前提下,调整激光束扫描速度(10～600 mm/s),以轮廓迂回法对猪脱细胞真皮基质进行打孔.分别测量打孔后真皮基质Triton X-100溶液浸泡洗涤前、后微孔入口及出口的孔径,计算真皮基质热损伤率.结果 激光束扫描速度小于或等于80 mm/s,热损伤率较低,微孔孔径变化不明显;随着激光束扫描速度的加快,热损伤率增大,孔径随之增大;当扫描速度加快至500 mm/s,孔径开始缩小;当扫描速度为600 mm/s,激光束不能穿透真皮基质形成微孔.结论 不同激光束扫描速度下,真皮基质微孔形成情况不同,综合考虑热损伤率与打孔效率,80 mm/s为最适宜的激光束扫描速度.     

辐射剂量对基于深度学习的计算机辅助诊断系统肺结节测量准确性的影响

目的 :通过胸部仿真体模实验,分析不同辐射剂量对基于深度学习的计算机辅助诊断系统(DL-CAD)测量肺结节长径及三维容积准确性的影响。方法:使用MSCT扫描含有8个不同直径(5、8、10、12 mm)和密度(实性、磨玻璃)的球形肺结节的成年男性仿真胸部体模。扫描参数:120 kV,噪声指数14,通过调整前置自适应统计迭代重建技术(pre-ASIR-V)的权重比例(0、40%、80%、100%)调整管电流。采用0、40%、80%比例的混合迭代算法(ASIR-V)重建12组薄层CT图像。应用DL-CAD测量体模内各个结节的长径和三维容积,比较不同辐射剂量条件下肺结节长径、三维容积测量的绝对百分误差(APE_d、APE_v)。采用单因素方差分析及LSD-t检验比较0、40%、80%、100%pre-ASIR-V扫描条件的APE_d和APE_v。结果:4次CT扫描的有效辐射剂量分别为9.68、3.78、0.82、0.23 mSv。随辐射剂量降低,肺结节的APE_d和APE_v逐渐增大(F=4.906,P=0.003;F=5.612,P=0.001),100%pre-ASIR-V的APE_d和APE_v显著大于其他扫描条件(均P0.05),其余各辐射剂量条件下两两比较差异均无统计学意义(均P 0.05)。结论:DL-CAD测量肺结节长径及三维容积的准确性与辐射剂量相关,低辐射剂量可显著降低测量准确性。     

256层螺旋CT定量评估左心耳结构与卒中的相关性

目的 采用256层螺旋CT对左心耳结构进行定量测量，评估其与非瓣膜性房颤患者发生脑卒中风险的相关性。方法 选取房颤患者80例，其中有脑卒中病史的40例为房颤伴卒中组，按照年龄及性别配对的方式选取同期40例房颤无脑卒中病史患者为房颤非卒中组。选用冠状动脉CTA 75%期相图像进行后处理，获取房颤患者的左心耳结构参数，对所得数据进行统计学分析。结果 1)房颤伴卒中组与房颤非卒中组比较，左心耳容积(LAAV)、左心耳容积指数(LAAVi)、左心耳开口面积、长径及短径均大于非卒中组(P<0.05)。以上数值增大，发生脑卒中的风险几率增加；2)当房颤患者左心耳容积>8.7 ml,预测发生脑卒中风险的价值最高，特异性达90.0%。结论 左心耳容积、容积指数、开口面积、长径及短径增大是房颤患者发生脑卒中的重要危险因素，当左心耳容积>8.7 ml脑卒中风险增加，该结果对临床指导房颤患者抗凝治疗具有重要临床意义。     

超高速投射物致伤作用的初步观察

创伤弹道学的研究表明 ,高速投射物的致伤能力取决于其能量、质量及飞行中的稳定性等因素 ,其中速度为最重要的因素[1 ] 。笔者在先前研究的基础上 ,将投射物的初速度提高至 3.0ｋｍ ｓ左右 ,以探讨超高速投射物的致伤作用并进一步研究速度在致伤中的作用。一、材料与方法1.致伤装置为二级气炮 (西北核工业研究所 ) ,钢珠 (外被纤维包膜 )直径1.0ｃｍ ,质量 1.0ｇ。射距 5 .0ｃｍ。靶标为生物靶标 (成年中国家兔 2只 ,雌性 ,第四军医大学实验动物中心提供 )、非生物靶标 (肥皂 2块 ,2 0ｃｍ× 2 0ｃｍ× 30ｃｍ ,按实验要求制作[2 ] )。2 .…     

动态CT显示肝细胞癌的最佳时相选择

为了确定表现为高密度肿块的肝细胞癌在动态CT扫描早期时相的最佳时间选择与扫描方法,并确定其临床意义,作者回顾性分析39例肝细胞癌患者。其中17例经组织学证实、22例根据血管造影和/或血清胎甲球蛋白升高合并肝硬变而诊断。共分析61个瘤灶。直径<2cm的瘤灶因部分容积效应平均密度不能正确记录而未包括在内。静脉增强用碘异肽醇-300,开始80ml以2ml/s速度注入,后10ml以1ml/s速度注入。15例(30个瘤灶)用快速程序CT,扫描时间1s,间隔2.2s,层厚10mm。在患者屏息     

Tornwaldt's囊肿的影像学表现

目的 探讨Tornwaldt's囊肿的影像学表现.方法 收集7例临床证实的Tornwaldt's囊肿,分析其64排CT或1.5T MR的影像学表现并复习文献.结果 7例Tornwaldt's囊肿均位于鼻咽顶部正中位置,椭圆形4例,圆形3例.病变大小6～9 mm(短径)×8～13 mm(长径),平均7.6 mm(短径)×10.4 mm(长径).1例CT表现为圆形等密度影.MRI表现:T1WI 1例稍高信号,5例等、低信号;6例T2WI、FLAIR均为高信号,DWI(b=0 s/mm2)高信号,DWI(b=1000 s/mm2)等低信号.结论 Tornwaldt's囊肿有其特殊的好发部位,结合其特征性的影像学表现,可提高其与鼻咽部其他实性或囊性病变鉴别诊断的能力.     

Effect of initial projectile speed on contamination distribution in a lower extremity surrogate "wound track"

This article presents an experimental study that examines the relationship between initial projectile speed and bacterial distribution along a wound track due to surface contamination. A ballistic gelatin cylinder was used as a lower extremity surrogate, and surface contamination was simulated using circular filter paper moistened with a solution containing Escherichia coli strain K-12 that was previously transformed to express green fluorescent protein and be resistant to ampicillin. An 11.43-mm caliber round-nose lead projectile was shot through the contaminated area and into the extremity surrogate at firing velocities ranging from 61 to 199 m/s. The "wound track" was extracted and cut into 10 evenly spaced slices. Then, the permanent cavity was removed from each slice using a biopsy punch, liquefied, and grown on selective agar containing ampicillin. Direct and normalized bacterial colony counts and normalized extents of area covered by bacteria colonies were used to compare the differences between distribution trends corresponding to different projectile speeds. The results obtained showed that, for the cases considered, an increase in projectile speed resulted in a significant shift in the percentage of contamination from the "wound" entrance region to the "wound" exit region.     

Effects of rate of force development on EMG amplitude and frequency

The purpose of this study was to compare the amplitude and frequency of the gastrocnemius EMG during ramp and ballistic contractions in highly trained sprint athletes. Sixteen female sprinters performed ramp and ballistic isometric contractions on a Biodex dynamometer. RMS and median frequency of the gastrocnemius EMG signals were obtained at the following torque levels: 25 +/- 5 %, 50 +/- 5 %, 75 +/- 5 %, 100 % MVC. The average rate of force development (RFD), was 610.2 +/- 123.1 N . m/s and 212.3 +/- 155.6 N . m/s for the ballistic and ramp contractions, respectively. In the ramp contractions the EMG amplitude increased as a function of torque. In the ballistic contractions the EMG amplitude decreased from 25 % to 100 % MVC. The highest RFD of 889.45 N . m/s was generated in ballistic contractions by a muscular activation pattern with high EMG amplitude (475.7 microV) and low frequency (116.7 Hz) at 25 % MVC. The findings suggest that the CNS utilizes different muscular activation patterns to modulate RFD in ramp and ballistic contractions. In ramp contractions the EMG amplitude increased linearly with force. In ballistic contractions a high RFD is generated with a muscular activation pattern consisting of high amplitude and low frequency at the start of the contraction.     

Atypical gunshot entrance wound and extensive backspatter

This case report describes a suicidal gunshot to the head using a solid hollow-point bullet (Quick Defense). There was an irregular skin defect measuring 16×6 cm on the right side of the head and a bone defect of 9×6 cm while a 1.2×0.7 cm skin defect was located at the left temple. This atypical wound morphology caused confusion at the scene but during autopsy, a muzzle imprint and an abrasion ring were found in the frontal aspect of the large skin defect in the right temporoparietal region, which therefore had to be the entrance wound. In addition, extensive backspatter consisting of brain tissue, bone fragments and blood had been expelled from the huge entrance wound and had travelled up to a distance of 4.6 m. The extraordinary entrance wound cannot be fully explained by special anatomical or ballistic features such as a muzzle velocity of 420 m/s or the solid hollow-point design of the bullet.     

Metabolic costs and heart rate responses to treadmill walking in water at different depths and temperatures

Treadmill walking/jogging in water is a potentially useful therapeutic modality. Since energy costs of this activity are unknown, we compared oxygen consumption (VO2) of treadmill walking/jogging in water to a dry treadmill at speeds of 40.23 to 160.9 meters/min (m/m) in 13.4 m/m increments in 11 subjects. At speeds greater than or equal to 53.6 m/m, ankle depth, below knee, midthigh, and waist depth walking/jogging in water significantly elevated VO2 and heart rate (HR) above dry treadmill walking (P less than 0.05). At speeds greater than or equal to 134.1 m/m, VO2 of waist depth jogging was not significantly greater than dry jogging. These findings showed no gender specificity. Treadmill walking/jogging in waist depth water at temperatures of 30.5 degrees C and 36.1 degrees C was compared to dry treadmill walking in five subjects. The rate of increase of HR compared to VO2 was significantly greater at 30.5 degrees C than dry walking, and greater at 36.1 degrees C than 30.5 degrees C (P less than 0.05). Treadmill walking in water can double the oxygen cost of movement depending on the depth and speed, and the response to increasing speed is nonlinear. Water temperature affects the relationship of HR to VO2 at waist depth, suggesting that water temperature can add a significant thermal load to the cardiovascular system. Metabolic and cardiovascular demands of treadmill walking/jogging in water must be considered when using this modality since greater external work results at much lower speeds than on land.     

Annular distribution patterns of .357 Magnum fragments in soft tissue simulants after striking hard material that prevented the bullet from exiting

The distribution of bullet fragments inside the body can provide information for the reconstruction of events in shooting incidents. The formation of an annular distribution pattern of bullet fragments was recently presented in a case report. The fragments were scattered radially around an exit-re-entrance wound resulting from collision of the bullet with a floor tile immediately after perforating the body. Such an annular distribution pattern of bullet fragments around an exit-re-entrance wound would indicate that a body was in close contact with hard material, for instance, lying on hard ground or leaning against a concrete wall, when the shot was fired. The aim of this experimental study was to investigate the formation and reproducibility of the annular distribution pattern of bullet fragments. It was assumed that the distribution pattern would be formed when hard material blocks a bullet from exiting a soft tissue simulant. Furthermore, the dependency of this distribution pattern on the impact angle was assessed. For this purpose, .357 Magnum bullets were fired at ballistic soap blocks with a steel plate at the rear end of the soap block. Six shots were performed at an impact angle of 90° (experiment 1), and six shots were performed at an impact angle of 45° (experiment 2). The distribution pattern of the fragments inside the individual soap blocks was examined via computed tomography (CT). In experiment 1, the bullets burst, and large fragments formed annular distribution patterns with a radial extent of approximately 4.9 cm and a maximum depth of approximately 2.3 cm. In experiment 2, the bullets ricocheted from the steel plate, and tiny fragments formed small annular distribution patterns at the points of ricochet with a radial extent of approximately 1.5 cm and a maximum depth of approximately 1.2 cm. The end position of the large main fragments was approximately 9.7 cm distant from the point of ricochet at a mean depth of 2.7 cm. The mean kinetic energy of the bullets at the time of impact was 580 J in experiment 1 and 394 J in experiment 2. Distribution patterns of bullet fragments in the body may provide information not only on the impact angle of a bullet but also on whether the body was in contact with a hard material that blocked the bullet from exiting the body. CT proved to be an appropriate imaging method for such investigations.     

Wheelchair racing: effects of rim diameter and speed on physiology and technique

Effects of different hand rim diameters in wheelchair racing were studied with respect to physiological and technique parameters at five speed levels (N = 8 wheelchair sportsmen). In each of five subsequent 15-min exercise tests on a treadmill, a different sized hand rim was mounted to the rear wheels (0.3, 0.35, 0.38, 0.47, 0.56 m). In each test, speed increased with 0.83 m.s-1 every 3 min, starting at 0.83 m.s-1 and ranging up to 4.17 m.s-1 (slope: 0.5 degrees). Cardiorespiratory responses (ventilation, oxygen cost, heart rate, respiratory exchange ratio, mechanical efficiency) and timing data (cycle time, push time, recovery time, push angle, and work per cycle) were obtained every 3rd min, together with the movement pattern of trunk and arm segments. Clear effects of rim diameter and speed were seen for the physiological parameters (P less than 0.05). In physiological terms, D5 appeared the least beneficial, followed by D4. Moreover, increasing rim diameter had a significant effect on movement pattern of the upper arm in the sagittal as well the frontal plane of motion. However, no timing effects were seen with changing rim diameter. On the other hand, timing parameters varied markedly with speed, whereas the segmental excursions of the upper limb did not show a "speed-effect". In general, small hand rims show lower cardiorespiratory responses. This may be related to the decreased segmental excursions of the upper limb and the lower linear hand velocity. Together with a low rolling and air drag, heart rate, and oxygen cost, these are important prerequisites in racing events.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isokinetic strength and anaerobic power of elite, subelite and amateur French soccer players

Information about the influence of different practice levels on physical characteristics of a large number of soccer players is lacking. Therefore we assessed muscular strength and anaerobic power of elite, subelite and amateur soccer players to clarify what parameters distinguish the top players from the less successful. We tested 95 soccer players from the French first division (elite), second division (subelite), and amateurs and determined the isokinetic strength of the knee extensor and flexor muscles at angular velocities from -120 degrees x s(-1) to 300 degrees x s(-1). Vertical jump, 10 m sprint, 30 m sprint and maximum ball speed during shooting were also measured. The elite players had higher knee flexor torque than the amateurs at all angular velocities (p < 0.05), except at 300 degrees x s(-1). The hamstring/quadriceps ratios proposed with two different methods were significantly lower in the amateur group than in the elite group (p < 0.05), except at 300 degrees x s(-1). Maximum ball speed during shooting and speed over 30 m sprint were not different between elite, subelite, and amateur players while speed over a 10 m sprint was significantly slower in amateur players and faster in the elite group (p < 0.05). Although performance in soccer is not determined only by measurable variables, professional players differ from amateurs in terms of knee flexor muscle strength and short-distance sprinting speed. Based on these findings we conclude that hamstring strength is extremely important in soccer players for joint stabilization during various tasks, notably in eccentric action. Further, short-sprinting performance may mirror actual game situations at high level and could be an important determinant of match-winning actions.     

颅脑损伤动物模型制备及脑组织中神经生长因子、脑源性神经营养因子变化的实验研究

目的：为研究提供重复性好、损伤程度稳定的颅脑损伤（ TBI）模型制备方法。方法选取65只SD大鼠,随机分为空白组（A组,没有处理）、模型1组（B组：打击速度3m／s,深度3mm）、模型2组（C组：打击速度4m／s,深度3mm）、模型3组（D组：打击速度5m／s,深度3mm）和假手术组（E组,只开颅,不进行打击）,使用电子颅脑损伤仪（ eCCI,美国弗吉尼亚联邦大学设计）选定不同打击参数制备不同损伤程度的TBI模型,通过检测脑皮层中神经生长因子（NGF）、脑源性神经营养因子（BDNF）含量变化评测模型制备效果。结果空白组和假手术组大鼠损伤脑组织大脑皮质神经元胞浆中NGF、BDNF均有弱阳性反应。模型各组损伤后脑组织损伤区大脑皮质脑神经元胞浆中NGF、BDNF呈强阳性反应,表达明显增多,且随损伤打击速度的增加而增多,各组之间比较具有统计学意义（ P＜0.01）。结论利用eCCI仪器制备TBI模型大鼠能够通过打击速度、打击深度参数的设置而精确控制模型的损伤程度,具有易操作、打击强度可控制、重复性好的优点,能够根据研究需要制备理想损伤程度的动物模型。     

Void fraction and velocity measurement of simulated bubble in a rotating disc using high frame rate neutron radiography.

To evaluate measurement error of local void fraction and velocity field in a gas-molten metal two-phase flow by high-frame-rate neutron radiography, experiments using a rotating stainless-steel disc, which has several holes of various diameters and depths simulating gas bubbles, were performed. Measured instantaneous void fraction and velocity field of the simulated bubbles were compared with the calculated values based on the rotating speed, the diameter and the depth of the holes as parameters and the measurement error was evaluated. The rotating speed was varied from 0 to 350 rpm (tangential velocity of the simulated bubbles from 0 to 1.5 m/s). The effect of shutter speed of the imaging system on the measurement error was also investigated. It was revealed from the Lagrangian time-averaged void fraction profile that the measurement error of the instantaneous void fraction depends mainly on the light-decay characteristics of the fluorescent converter. The measurement error of the instantaneous local void fraction of simulated bubbles is estimated to be 20%. In the present imaging system, the light-decay characteristics of the fluorescent converter affect the measurement remarkably, and so should be taken into account in estimating the measurement error of the local void fraction profile.