How cat lands: insights into contribution of the forelimbs and hindlimbs to attenuating impact force

To safely land after different drops, cats can perfectly use their limbs as dampers to dissipate impact forces. Yet, we know little about the contribution of the forelimbs and hindlimbs of cats to attenuating the impact forces during landing. In order to investigate this, we analyzed the landing impulses and energy absorption based on the ground reaction forces and high-speed video recordings of cats performing self-initiated jump downs at different heights. Our results show that the distribution of impact forces between forelimbs and hindlimbs exhibits a landing height-dependent manner. Furthermore, combining the experimental measurements and the inverted pendu- lum-spring model, we find that variation in landing angle is correlated with the distribution manner. This posture- dependent actuation allows the animal to tune the distri- bution of energy absorption between forelimbs and hind- limbs. These findings highlight how cats perfectly jump down using their limbs, providing fundamental insights into the importance of control mechanisms that attenuate landing impulses safely and efficiently.     

仿生海龟前肢推进装置

本作品目的在于研制出一种新型的推进装置，以适用于水下机器人。利用仿生学原理，以海龟水翼法游动为原型，开发出仿海龟水翼法游动的新型水下推进装置。仿生海龟的水翼法游动形式是本作品的关键技术。其运动的平稳性、可控性为其主要技术指标。目前的水下机器人大多有速度慢、效率低、运动姿态简单、     

动物为什么是五指（趾）？

长久以来，人们都惊叹于大自然的伟大创造力，地球上的众多生灵有着极为精巧的结构以适应其生存的环境。大象的四肢极为粗壮以支撑庞大的身躯，蝙蝠细长而灵巧的前肢支撑着用于飞翔的皮膜，海豚呈鳍状的前肢犹如船桨是划水的利器，长臂猿的手指修长而灵活令其能在大树之间自由地穿梭，而笔者对人类那灵巧的双手尤为惊叹。     

双峰驼前肢深静脉解剖

首次报道了双峰驼前肢深静脉回流前肢组织器官静脉血的情况,如其属支,主干的走行路线等。结果表明：双峰驼前肢深静脉中的腋静脉由臂静脉后干和肩胛下静脉汇合而成,最后至第一肋骨胸骨端前外侧面折转向内侧行,在胸前口前方汇注于前腔静脉,壁静脉分前干和后干,起于臂静脉冲干;正中静脉在掌近端由第Ⅲ,Ⅳ指掌侧总静脉汇合而成,在前臂骨下端分为内,外侧干。正中静脉在肱骨内侧面前上方注入臂静脉干。     

吃白蚁的蛙

<正>科学家在澳大利亚西部发现了一种极稀有的、奇特的、只有手掌心大小的蛙。这种蛙只吃白蚁,不吃其他的