Bringing the “General Strike” Back In: DuBois,Slavery and Emancipation

ABSTRACT

The “general strike” of slaves in the Civil War was a direct action that involved millions of small and large acts of defiance by slaves. These actions pushed President Lincoln from hesitation to full on military action, although this chapter of history has been neglected. The work of W.E.B. Du Bois reinserted the agency of slaves in their own liberation through the “general strike” but this analysis has also been pushed to the margins. David Roediger's “Seizing Freedom: Slave Emancipation and Liberty for All' is an important corrective to this historical omission.     

Initial contact and toe off event identification for rearfoot and non-rearfoot strike pattern treadmill running at different speeds

The purpose of this study was to determine the validity of kinematic based initial contact (IC) and toe-off (TO) identification algorithms for rearfoot and non-rearfoot runners across a broad range of treadmill running speeds. 14 healthy active participants completed six 20–60 s treadmill running trials at 6 speeds: 2.24, 2.68, 3.13, 3.58, 4.02, and 4.48 ms⁻¹. 3D kinematic data were collected for the last 20 s of each trial. Force plates (FP) were used as the gold standard to determine ICFP and TOFP for each step. Three algorithms for finding IC, IC_Milner, IC_Alvim, IC_Alvim-mod, and one algorithm for finding toe off, TO_Fellin, were chosen for analysis. Root mean square errors (RMSE) and difference scores with 95% confidence intervals were computed for IC, TO and stance time (ST). IC_Alvim RMSE ranged from 0.175 to 0.219 s. ST_Alvim RMSE ranged from 0.168 to 0.216 s. IC_Alvim-mod RMSE ranged from 0.105 to 0.131 s. ST_Alvim-mod RMSE ranged from 0.108 to 0.129 s. IC_Milner RMSE ranged 0.012 to 0.015 s. ST_Milner RMSE ranged 0.019 to 0.024 s. IC_Milner accuracy was inversely related to speed. IC_Milner corrected with a linear regression equation reduced differences to- 0.006 ± 0.012 s with 86% of foot strikes identified within 20 ms and 58% with 10 ms. TO_Fellin RMSE ranged from 0.012 to 0.016 s. IC_Milner adjusted for speed and TO_Fellin can be used to predict IC and TO within a broad range of treadmill running speeds (2.24–4.48 ms⁻¹) and for rearfoot and non-rearfoot strikers.     

Aeroecology meets aviation safety: early warning systems in Europe and the Middle East prevent collisions between birds and aircraft

The aerosphere is utilized by billions of birds, moving for different reasons and from short to great distances spanning tens of thousands of kilometres. The aerosphere, however, is also utilized by aviation which leads to increasing conflicts in and around airfields as well as en‐route. Collisions between birds and aircraft cost billions of euros annually and, in some cases, result in the loss of human lives. Simultaneously, aviation has diverse negative impacts on wildlife. During avian migration, due to the sheer numbers of birds in the air, the risk of bird strikes becomes particularly acute for low‐flying aircraft, especially during military training flights. Over the last few decades, air forces across Europe and the Middle East have been developing solutions that integrate ecological research and aviation policy to reduce mutual negative interactions between birds and aircraft. In this paper we 1) provide a brief overview of the systems currently used in military aviation to monitor bird migration movements in the aerosphere, 2) provide a brief overview of the impact of bird strikes on military low‐level operations, and 3) estimate the effectiveness of migration monitoring systems in bird strike avoidance. We compare systems from the Netherlands, Belgium, Germany, Poland and Israel, which are all areas that Palearctic migrants cross twice a year in huge numbers. We show that the en‐route bird strikes have decreased considerably in countries where avoidance systems have been implemented, and that consequently bird strikes are on average 45% less frequent in countries with implemented avoidance systems in place. We conclude by showing the roles of operational weather radar networks, forecast models and international and interdisciplinary collaboration to create safer skies for aviation and birds.     

VESSEL COLLISIONS WITH WHALES: THE PROBABILITY OF LETHAL INJURY BASED ON VESSEL SPEED

Historical records demonstrate that the most numerous, per capita, ocean-going-vessel strikes recorded among large-whale species accrue to the North Atlantic right whale ( Eubalaena glacialis ). As vessel speed restrictions are being considered to reduce the likelihood and severity of vessel collisions with right whales, we present an analysis of the published historical records of vessels striking large whales. We examine the influence of vessel speed in contributing to either a lethal injury (defined as killed or severely injured) or a nonlethal injury (defined as minor or no apparent injury) to a large whale when struck. A logistic regression model fitted to the observations, and consistent with a bootstrap model, demonstrates that the greatest rate of change in the probability of a lethal injury ( P _lethal) to a large whale occurs between vessel speeds of 8.6 and 15 knots where P _lethal increases from 0.21 to 0.79. The probability of a lethal injury drops below 0.5 at 11.8 knots. Above 15 knots, P _lethal asymptotically approaches 1. The uncertainties in the logistic regression estimates are relatively large at relatively low speeds ( e.g. , at 8 knots the probability is 0.17 with a 95% CI of 0.03–0.6). The results we provide can be used to assess the utility of vessel speed limits that are being considered to reduce the lethality of vessels striking the critically endangered North Atlantic right whale and other large whales that are frequent victims of vessel strikes.     

Faecal soiling and gastrointestinal helminth infection in lambs

The accumulation of faeces in the wool of the breech area (tail, perineum and anus) of lambs, known as faecal soiling, has been shown to be one of the major factors predisposing sheep to blowfly strike. However, the causes of faecal soiling of lambs in the UK are not clearly understood. Hence, in this investigation, the relationships between faecal soiling, gastrointestinal parasitic nematode infection and resultant diarrhoea were examined in a longitudinal study of 200 lambs at two farms in south-west England. Faecal egg counts, pasture worm burdens, faecal soiling and growth rates were recorded for individually tagged lambs over the summer of 2003. Grass growth and nutritional composition (protein and fibre) and weather data were also recorded over this period. Analysis using linear mixed models showed that faecal soiling was associated with higher strongyle-type egg counts, longer periods since worming, lower live-weights, female gender, lower faecal consistency and pasture quality. The data indicate that dag scoring, especially in mid- to late summer, could be used as a rapid, non-invasive technique for selecting animals, particularly lambs, with high faecal egg counts for selective drenching to reduce the incidence of anthelmintic resistance. Selective drenching of lambs with high dag scores would also be expected to aid in the control of blowfly strike.     

机场周边家鸽飞行行为的潜在鸟击风险初步研究

鸟击防控是一个世界性难题。家鸽（Columba livia domestica）是机场生物多样性调查中最常见鸟类,也是历史上鸟击高危物种之一,还是唯一由于人工大量放飞导致严重鸟击事故的物种。2020年9月至2021年1月,在我国4个机场,针对机场周边23家鸽户,共149只家鸽开展卫星追踪放飞实验研究,获得了家鸽个体在机场周边的飞行时间、飞行距离、飞行高度等个体运动参数。研究发现,1）单次放飞时长多在1 ~ 4 h,单次平均放飞时长为（2.9 ± 1.6）h。在鸽户自主放飞家鸽和家鸽自由回笼的动态过程中,下午活动在外的家鸽数量较多,尤其15:00 ~ 17:59时段是活动在外家鸽数量最多的时段。2）飞行距离多在3.0 km范围内,最远可达8.9 km;存在家鸽飞行范围覆盖机场现象的鸽户占比45%。3）飞行高度主要在200 m及以下,平均飞行高度为（29 ± 28）m。本研究结果表明,下午,尤其是15:00 ~ 17:59时段应作为家鸽防控的重点时段,机场周边10 km以及高度0 ~ 200 m的范围应作为家鸽防控的重点空间范围。根据《中华人民共和国民用航空法（2021修正）》第五十八条明确规定“不得饲养、放飞影响飞行安全的鸟类动物和其他物体”,需要建立相应的问责机制、加强有效监管,以降低家鸽鸟击风险。     

Consequences of injuries on survival and reproduction of common bottlenose dolphins (Tursiops truncatus) along the west coast of Florida

Accurate identification of human‐induced injuries that lead to death or interfere with reproduction is important for marine mammal management, as deaths exceeding established limits can lead to restrictions on fisheries or vessel operations. The fates of cetaceans last seen swimming with attached gear, particularly in pelagic fisheries, or with vessel strike lacerations, have been difficult to predict. Survival and reproduction data from long‐term research on resident common bottlenose dolphins near Sarasota, Florida were examined relative to consequences of fishing gear ingestion, line entanglements, vessel strikes, and amputations of unknown origins. Fishing hooks embedded in the throat, goosebeak, or esophagus, or line wrapped around the goosebeak, generally lead to death. Multiple, constrictive line wraps around fin insertions can lead to amputation, blood loss, impaired mobility, or infection. Dolphins with ingested gear or severe entanglements may swim away with the gear, but likely die later. Propeller injuries involving only soft tissue were often survivable. Some dolphins survived amputations of the distal ends of fins, and continued to reproduce. As a precautionary approach, dolphins with ingested gear or severe constrictive entanglements should be considered mortalities, but extrapolations of findings from coastal bottlenose dolphins to other cetaceans and different gear must be done with caution.     

Consequences of forward translation of the point of force application for the mechanics of running

In running humans, the point of force application between the foot and the ground moves forwards during the stance phase. Our aim was to determine the mechanical consequences of this 'point of force translation' (POFT). We modified the planar spring-mass model of locomotion to incorporate POFT, and then compared spring-mass simulations with and without POFT. We found that, if leg stiffness is adjusted appropriately, it is possible to maintain very similar values of peak vertical ground reaction force (GRF), stance time, contact length and vertical centre of mass displacement, whether or not POFT occurs. The leg stiffness required to achieve this increased as the distance of POFT increased. Peak horizontal GRF and mechanical work per step were lower when POFT occurred. The results indicate that the lack of POFT in the traditional spring-mass model should not prevent it from providing good predictions of peak vertical GRF, stance time, contact length and vertical centre of mass displacement in running humans, if an appropriate spring stiffness is used. However, the model can be expected to overestimate peak horizontal GRF and mechanical work per step. When POFT occurs, the spring stiffness in the traditional spring-mass model is not equivalent to leg stiffness. Therefore, caution should be exercised when using spring stiffness to understand how the musculoskeletal system adapts to different running conditions. This can explain the contradictory results in the literature regarding the effect of running speed on leg stiffness.     

MODULARITY AND SCALING IN FAST MOVEMENTS: POWER AMPLIFICATION IN MANTIS SHRIMP

Extremely fast animal actions are accomplished with mechanisms that reduce the duration of movement. This process is known as power amplification. Although many studies have examined the morphology and performance of power‐amplified systems, little is known about their development and evolution. Here, we examine scaling and modularity in the powerful predatory appendages of a mantis shrimp, Gonodactylaceus falcatus (Crustacea, Stomatopoda). We propose that power‐amplified systems can be divided into three units: an engine (e.g., muscle), an amplifier (e.g., spring), and a tool (e.g., hammer). We tested whether these units are developmentally independent using geometric morphometric techniques that quantitatively compare shapes. Additionally, we tested whether shape and several mechanical features are correlated with size and sex. We found that the morphological regions that represent the engine, amplifier, and tool belong to independent developmental modules. In both sexes, body size was positively correlated with the size of each region. Shape, however, changed allometrically with appendage size only in the amplifier (both sexes) and tool (males). These morphological changes were correlated with strike force and spring force (amplifier), but not spring stiffness (amplifier). Overall, the results indicate that each functional unit belongs to different developmental modules in a power‐amplified system, potentially allowing independent evolution of the engine, amplifier, and tool.