Jumping with adhesion: landing surface incline alters impact force and body kinematics in crested geckos

Arboreal habitats are characterized by a complex three-dimensional array of branches that vary in numerous characteristics, including incline, compliance, roughness, and diameter. Gaps must often be crossed, and this is frequently accomplished by leaping. Geckos bearing an adhesive system often jump in arboreal habitats, although few studies have examined their jumping biomechanics. We investigated the biomechanics of landing on smooth surfaces in crested geckos, Correlophus ciliatus, asking whether the incline of the landing platform alters impact forces and mid-air body movements. Using high-speed videography, we examined jumps from a horizontal take-off platform to horizontal, 45° and 90° landing platforms. Take-off velocity was greatest when geckos were jumping to a horizontal platform. Geckos did not modulate their body orientation in the air. Body curvature during landing, and landing duration, were greatest on the vertical platform. Together, these significantly reduced the impact force on the vertical platform. When landing on a smooth vertical surface, the geckos must engage the adhesive system to prevent slipping and falling. In contrast, landing on a horizontal surface requires no adhesion, but incurs high impact forces. Despite a lack of mid-air modulation, geckos appear robust to changing landing conditions.

PCNA Loaders and Unloaders—One Ring That Rules Them All

During each cell duplication, the entirety of the genomic DNA in every cell must be accurately and quickly copied. Given the short time available for the chore, the requirement of many proteins, and the daunting amount of DNA present, DNA replication poses a serious challenge to the cell. A high level of coordination between polymerases and other DNA and chromatin-interacting proteins is vital to complete this task. One of the most important proteins for maintaining such coordination is PCNA. PCNA is a multitasking protein that forms a homotrimeric ring that encircles the DNA. It serves as a processivity factor for DNA polymerases and acts as a landing platform for different proteins interacting with DNA and chromatin. Therefore, PCNA is a signaling hub that influences the rate and accuracy of DNA replication, regulates DNA damage repair, controls chromatin formation during the replication, and the proper segregation of the sister chromatids. With so many essential roles, PCNA recruitment and turnover on the chromatin is of utmost importance. Three different, conserved protein complexes are in charge of loading/unloading PCNA onto DNA. Replication factor C (RFC) is the canonical complex in charge of loading PCNA during the S-phase. The Ctf18 and Elg1 (ATAD5 in mammalian) proteins form complexes similar to RFC, with particular functions in the cell’s nucleus. Here we summarize our current knowledge about the roles of these important factors in yeast and mammals.

OaAEP1-mediated PNA-protein conjugation enables erasable imaging of membrane protein

Methods to efficiently and site-specifically conjugate proteins to nucleic acids could enable exciting application in bioanalytics and biotechnology. Here, we report the use of the strict protein ligase to covalently ligate a protein to a peptide nucleic acid (PNA). The rapid ligation requires only a short N-terminal GL dipeptide in target protein and a C-terminal NGL tripeptide in PNA. We demonstrate the versatility of this approach by conjugating three different types of proteins with a PNA strand. The biostable PNA strand then serves as a generic landing platform for nucleic acid hybridization. Lastly, we show the erasable imaging of EGFR on HEK293 cell membrane through toehold-mediated strand displacement. This work provides a controlled tool for precise conjugation of proteins with nucleic acids through an extremely small peptide linker and facilitates further study of membrane proteins.

Precision Landing for Low-Maintenance Remote Operations with UAVs

This work proposes a fully integrated ecosystem composed of three main components with a complex goal: to implement an autonomous system with a UAV requiring little to no maintenance and capable of flying autonomously. For this goal, was developed an autonomous UAV, an online platform capable of its management and a landing platform to enclose and charge the UAV after flights. Furthermore, a precision landing algorithm ensures no need for human intervention for long-term operations.

Autonomous Landing of Micro Unmanned Aerial Vehicles with Landing-Assistive Platform and Robust Spherical Object Detection

Autonomous unmanned aerial vehicle (UAV) landing can be useful in multiple applications. Precise landing is a difficult task because of the significant navigation errors of the global positioning system (GPS). To overcome these errors and to realize precise landing control, various sensors have been installed on UAVs. However, this approach can be challenging for micro UAVs (MAVs) because strong thrust forces are required to carry multiple sensors. In this study, a new autonomous MAV landing system is proposed, in which a landing platform actively assists vehicle landing. In addition to the vision system of the UAV, a camera was installed on the platform to precisely control the MAV near the landing area. The platform was also designed with various types of equipment to assist the MAV in searching, approaching, alignment, and landing. Furthermore, a novel algorithm was developed for robust spherical object detection under different illumination conditions. To validate the proposed landing system and detection algorithm, 80 flight experiments were conducted using a DJI TELLO drone, which successfully landed on the platform in every trial with a small landing position average error of 2.7 cm.

The autonomous control of landing on mobile platforms

In this paper, we propose a simulation application that allows an aerial vehicle to land autonomously on a moving platform in the presence of uncertainties and disturbances. We have tested our method with various speeds and positions for the landing platform. In the context of this article, the autonomous control of landing on mobile platforms consists in synchronizing the movement of an aerial vehicle with the movement of the mobile platform. As a first step, the Spacelab INCAS laboratory group has developed an offline simulation application that allows an ABB robot to receive information on the movement of a Stewart-type mobile platform in order to conduct a landing process. The application can initiate a landing process on the mobile platform and guide the vehicle for perfect docking on the platform. Offline simulation allows the study of several scenarios of a robot working cell - the mobile platform before setting up the production cell. The offline application has a distributed client-server structure. The client communicates with the server through specific communication protocols. The client and server can reside on the same computer. The client application is developed in the Matlab environment and has as object the simulation and programming of the PS-6TL-1500 platform; the server one simulates and programs an ABB 7600-500/2.55 robot that moves on the track, in the RAPID language under RobotStudio ABB simulator.

Numerical Estimation of Relative Wave Elevation on a Semi-Submersible Vessel

Ambition of this research was to numerically reproduce the relative wave elevations measured on and around a semi-submersible vessel during model tests performed at MARIN (Maritime Research Institute of the Netherlands). Model tests were performed on a semi-submersible model representing, in different setup configurations, a heavy lift vessel and a LPD (Landing Platform Dock). Relative wave elevations were measured at 47 locations on and around the vessel. Tests were made with different regular wave conditions and headings, at anchor, with the model fixed in a soft mooring setup. Data from model tests were used to calibrate and run a time domain potential flow boundary element tool with particular focus on the relative wave elevation at the 47 locations. A comparison between numerical and experimental results is proposed in this paper.