소금쟁이과 거대 소금쟁이의 수면 위 거동에 대한 행동 및 형태학적 적응

학위논문(박사) -- 서울대학교대학원 : 자연과학대학 생명과학부, 2023. 8. Piotr G. Jablonski.Allometry is a study of the relationships between body size and other morphological and behavioral characteristics of an organism that result from the physics of the habitat and the biology of the organism living in its typical habitat. Water striders, Gerridae, is a good model taxon to study the locomotion and morphological adaptations to the laws of physics of their semiaquatic habitat: the water surface. The hydrodynamics and biomechanics of jumping and striding by water striders are well-understood in certain genera such as Gerris and Aquarius. Also, the hydrodynamic functions of micro hair structures on insect bodies have been studied in a relatively narrow range of water strider species. I studied two large-sized subtropical SE Asian species: Gigantometra gigas and Ptilomera tigrina. The body sizes of these species are approximately 2-10 times heavier than those of the typically studied species. The existing theory of jump of water striders predicts water striders use surface tension-dominant jump without surface breaking, which improves take-off velocity and reduces take-off delay. However, I observed that two large-sized species jump with surface-breaking and do not follow the existing theory of jump. I corrected the previous model without concerning drag to a model that includes drag calculation. The model shows that heavy species should break the water surface and utilize drag for thrust to achieve enough jump performance to escape from underwater predators. I developed another model that simulates floating conditions and sliding resistance of striding water striders. The model reveals that in order to float on the water surface, heavy species should have developed long forelegs to support the anterior part of the body with symmetric striding (two forelegs support the anterior body and two midlegs thrust simultaneously), or use asymmetric striding (one stretched forward midleg support the anterior body and another midleg and a contralateral hindleg thrust). The data on behavior observations and morphological measurements were consistent with the results of the model simulations. I explored the detailed micro-morphology of hair structures of the two species and observed how these structures are used by insects, by using scanning electron microscopy, optical microscopy, x-ray microscopy, and high-speed videography. The feasible match between the locomotive behavior of using legs and morphological characteristics of hairs implied hypothetical adaptive functions of these distinct hair structures of the two large species in comparison to the typical medium-sized water strider, A. paludum, that lives on stagnant water. Special hair brushes on the thrusting legs of P. tigrina were linked with their extremely fast striding behavior and fast-flowing habitat preference proven in this thesis. The theoretical modeling, observations, and experiments show how Gerridae illustrate adaptative links between the behavior, morphology, and habitat characteristics of organisms.Allometry는 서식지의 물리법칙과 유기체의 생물학적 특성으로 결정된 형태학 및 행동학적 특성이 몸 크기와 주고 받는 상호관계에 대한 연구이다. 소금쟁이과에 속하는 반수생 곤충들은 수표면이라는 특정한 환경에 살기 때문에 수면에서 활동하는 생명체의 운동을 관찰하고 수면의 물리법칙에 적응하여 습득한 형태학적 특징을 연구하기 위한 적합한 분류군이다. 소금쟁이의 수직도약과 수평이동에 대한 기존 연구들은 Gerris 및 Aquarius 와 같은 특정 분류군에 속하는 종을 대상으로 유체 역학 및 생체 역학적 원리에 초점을 맞춰왔다. 또한 몸체에 있는 미세모 구조의 유체 역학적 기능도 비교적 좁은 범위의 소금쟁이 종에서 연구되었다. 본 연구는 동남아에서 서식하는 Gigantometra gigas와 Ptilomera tigrina를 관찰, 실험 및 이론적 모델링을 진행함으로서 소금쟁이과(Gerridae)의 적응을 행동, 형태 및 서식지 특성으로 설명하고자 하였다. 이 종들의 몸무게는 기존 연구에서 널리 다뤘던 종들보다 2배에서 10배 가량 무겁기 때문에 지금껏 보고되었던 연구 모델의 가용성은 베일에 쌓여 있었다. 소금쟁이의 수직도약을 예측하는 기존 연구 모델은 수면의 표면 장력이 도약의 주요 추진력을 제공하기 때문에 소금쟁이가 수면을 깨지 않고 도약하여 도약 속도를 향상시키고 수표면 탈출 지연시간을 줄이는 것으로 예측했다. 하지만 본 연구에서 다루는 두 대형 종은 기존의 예측과 달리 수면을 깨뜨리면서 도약하기 때문에 기존 모델에 항력과 표면장력을 모두 포함하도록 수정하였다. 이를 토대로 두 종의 수직도약을 예측해본 결과, 표면장력 외에도 항력을 추진력으로 활용해야만 수중 포식자로부터 탈출하기에 충분한 도약 성능을 낼 수 있었다. 이밖에도 소금쟁이가 수면 위에 떠있기 위한 조건과 수면 위에서 미끄러질 때의 저항을 예측하는 모델도 개발하였다. 그 결과로 무거운 소금쟁이 종은 좌우 비대칭 추진(앞으로 뻗은 하나의 중간 다리가 앞쪽 몸체를 떠받치고 반대편 중간다리와 뒤쪽의 뒷다리로 추진하는 방식)을 하거나 좌우 대칭 추진(양쪽 앞다리가 앞쪽 몸체를 떠받치고 양쪽 중간다리로 동시에 추진하는 방식)을 하되 다른 종들보다 긴 앞다리로 앞쪽 몸체를 지지해야만 수면에 떠있을 수 있었다. 본 연구에서 시행된 행동 관찰과 형태학적 측정 데이터 또한 모델 예측 결과와 일치했다. 두 종의 자세한 마이크로 털 구조체와 그 사용방식은 주사전자현미경, 광학현미경, X선현미경, 고속영상촬영을 이용하여 관찰되었다. 흐르지 않는 물 위에 사는 일반적 크기의 소금쟁이 종인 A. paludum과 비교했을 때, 두 거대한 소금쟁이 종의 다리 사용 방식과 털의 형태학적 특성의 일치는 두 종의 독특한 털 구조체의 적응에 대한 가설을 시사한다. P. tigrina의 추진용 중간다리에 자라 있는 특수한 빗형 털 구조체는 이 연구에서 보여준 빠른 유속 서식지 선호도 및 고속 수평 이동과 관련이 있었으며 G. gigas의 중간다리의 긴 미세모와 뒷다리의 특수한 미세모로 이루어진 빔형태의 구조체 또한 좌우 비대칭 추진과 관련이 있는 것으로 보인다. 본 연구는 이론적 모델링과 관찰 및 실험을 사용해 소금쟁이과(Gerridae)의 행동 및 형태학적 적응을 서식지 특성에 연결하여 설명한다.Chapter 1. General Introduction 5 Chapter 2. Two different jumping mechanisms of water striders are determined by body size 12 Chapter 3. Physics of sliding on water predicts morphological and behavioral allometry across a wide range of body sizes in water striders (Gerridae) 72 Chapter 4. Functional micro-morphology of setae on legs of the heaviest semi-aquatic insect, the giant water strider (Gigantometra gigas) 119 Chapter 5. The micro-morphology of ribbon-like setae on midlegs of a large water strider from lotic habitats, Ptilomera tigrina, and their role in locomotion on the water surface 164 Chapter 6. Locomotion and flow speed preferences in natural habitats by large water striders, Ptilomera tigrina, with micro-morphological adaptations for rowing 187 Chapter 7. General discussion 210 References 221 Abstract in Korean 236박

Locomation strategies for amphibious robots-a review

In the past two decades, unmanned amphibious robots have proven the most promising and efficient systems ranging from scientific, military, and commercial applications. The applications like monitoring, surveillance, reconnaissance, and military combat operations require platforms to maneuver on challenging, complex, rugged terrains and diverse environments. The recent technological advancements and development in aquatic robotics and mobile robotics have facilitated a more agile, robust, and efficient amphibious robots maneuvering in multiple environments and various terrain profiles. Amphibious robot locomotion inspired by nature, such as amphibians, offers augmented flexibility, improved adaptability, and higher mobility over terrestrial, aquatic, and aerial mediums. In this review, amphibious robots' locomotion mechanism designed and developed previously are consolidated, systematically The review also analyzes the literature on amphibious robot highlighting the limitations, open research areas, recent key development in this research field. Further development and contributions to amphibious robot locomotion, actuation, and control can be utilized to perform specific missions in sophisticated environments, where tasks are unsafe or hardly feasible for the divers or traditional aquatic and terrestrial robots

Nature inspired surface/interface engineering towards advanced device applications

Nature inspired surface/interface with multi-faceted functions possess promises in the frontier engineering applications in flexible electronics, energy harvesting, autonomous systems, bio-mimicking tissues, micro-fluidics, etc. Understanding the relationship between nature’s architecture and underlying science could bring enabling solutions to overcome the engineering challenges. A nature inspired surface with smart resilient features provides intrinsic complexity and their multiplicity under different stimuli, i.e. chemical, physical, electronic, mechanical and (in some cases) biological properties. By mimicking/harvesting a variety of surface and interfacial features from nature, the final composition will display an integrative design to provide further explorations in deciphering the hidden physics towards advanced device applications in real world. Specifically, we bring a few engineering examples with chemical/physical approaches to construct artificial nano/micro-structured surface, yield various functional surface for different application scenarios. • A porous layer has been realised to provide controllable generation of microarchitecture to exhibit an anti-corrosion behaviour under UV exposure with multifaceted characteristics such as profound solar absorptivity, thermal emissivity. By further treating the surface with silane, a hybrid layer has been established with superhydrophobic and anti-icing features which shares innate interests in thermal transport/aero-space engineering. • The structural conformation/ elastic instabilities of the surface are exploited to devise an extreme switchable configuration to develop a morphing strategy for switchable lipophilic/oleophobic properties. The geometrical shift of soft structure is instructed to create a steady transition of surface topology rendering a unique switchable transition that are widely inspired in sub-sea/offshore engineering for oil and water separation. • We also develop a highly-replenishable thermal energy harvesting technology via a dynamical elasto-bouncing process of polymeric hydrogel to translate the thermal energy into useful elasto-kinetic energy, then further converted into electrical energy via a simple piezo-material based system, which paves way for a future portable and conformable energy harvesting tool in the regions of extreme geo-thermal residencies and industries. • Using a one drop filling technique along with interfacial pinning points between hydrophilic and hydrophobic, a unique microfluidic approach is presented to create heterogenous structures. By exploiting the communication between swelling mismatch of different functional groups, driven via in-plane and through thickness heterogeity, a highly complex 3D soft reconfiguration is achieved which is activated by stimulation inputs. • The theoretical understandings are exploited in the above applied engineering scenarios, such as elastic mechanics, morphing structure, surface/interface interactions and kinetics of of the polymer systems experienced on a hot surface, which offers further insights into the elastic recoiling evolution and tunability of the system for effective energy translation efficiency. We hope above approaches shed more lights on the nature inspired structure in device engineering, thus, advance the knowledge in the frontier science

Using MapReduce Streaming for Distributed Life Simulation on the Cloud

Distributed software simulations are indispensable in the study of large-scale life models but often require the use of technically complex lower-level distributed computing frameworks, such as MPI. We propose to overcome the complexity challenge by applying the emerging MapReduce (MR) model to distributed life simulations and by running such simulations on the cloud. Technically, we design optimized MR streaming algorithms for discrete and continuous versions of Conway’s life according to a general MR streaming pattern. We chose life because it is simple enough as a testbed for MR’s applicability to a-life simulations and general enough to make our results applicable to various lattice-based a-life models. We implement and empirically evaluate our algorithms’ performance on Amazon’s Elastic MR cloud. Our experiments demonstrate that a single MR optimization technique called strip partitioning can reduce the execution time of continuous life simulations by 64%. To the best of our knowledge, we are the first to propose and evaluate MR streaming algorithms for lattice-based simulations. Our algorithms can serve as prototypes in the development of novel MR simulation algorithms for large-scale lattice-based a-life models.https://digitalcommons.chapman.edu/scs_books/1014/thumbnail.jp

Macroevolution: Explanation, Interpretation and Evidence

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2015, UMaine News Press Releases

This is a catalog of press releases put out by the University of Maine Division of Marketing and Communications between January 2, 2015 and December 31, 2015

Massachusetts Domestic and Foreign Corporations Subject to an Excise: For the Use of Assessors (2004)

International audienc