Morphological computation of multi-gaited robot locomotion based on free vibration.

In recent years, there has been increasing interest in the study of gait patterns in both animals and robots, because it allows us to systematically investigate the underlying mechanisms of energetics, dexterity, and autonomy of adaptive systems. In particular, for morphological computation research, the control of dynamic legged robots and their gait transitions provides additional insights into the guiding principles from a synthetic viewpoint for the emergence of sensible self-organizing behaviors in more-degrees-of-freedom systems. This article presents a novel approach to the study of gait patterns, which makes use of the intrinsic mechanical dynamics of robotic systems. Each of the robots consists of a U-shaped elastic beam and exploits free vibration to generate different locomotion patterns. We developed a simplified physics model of these robots, and through experiments in simulation and real-world robotic platforms, we show three distinctive mechanisms for generating different gait patterns in these robots.

Morphological computation for adaptive behavior and cognition

Traditionally, in robotics, artificial intelligence and neuroscience, there has been a focus on the study of the control or the neural system itself. Recently there has been an increasing interest in the notion of embodiment not only in robotics and artificial intelligence, but also in the neurosciences, psychology and philosophy. In this paper, we introduce the notion of morphological computation, and demonstrate how it can be exploited on the one hand for designing intelligent, adaptive robotic systems, and on the other hand for understanding natural systems. While embodiment has often been used in its trivial meaning, i.e. "intelligence requires a body", the concept has deeper and more important implications, concerned with the relation between physical and information (neural, control) processes. Morphological computation is about connecting body, brain and environment. A number of case studies are presented to illustrate the concept. We conclude with some speculations about potential lessons for neuroscience and robotics. © 2006 Elsevier B.V. All rights reserved.

Self-stabilization and behavioral diversity of embodied adaptive locomotion

Locomotion is of fundamental importance in understanding adaptive behavior. In this paper we present two case studies of robot locomotion that demonstrate how higher level of behavioral diversity can be achieved while observing the principle of cheap design. More precisely, it is shown that, by exploiting the dynamics of the system-environment interaction, very simple controllers can be designed which is essential to achieve rapid locomotion. Special consideration must be given to the choice of body materials. We conclude with some speculation about the importance of locomotion for understanding cognition. © Springer-Verlag Berlin Heidelberg 2004.

Comparative studies on in vitro sperm decondensation and pronucleus formation in egg extracts between gynogenetic and bisexual fish

A cell-free system based upon the egg extracts from gynogenetic gibel carp (Carassius auratus gibelio) or bisexual red common carp (Cyprinus carpio red variety) was developed to investigate developmental behaviors of the demembranated sperm nuclei. Both red common carp and gibel carp sperm nuclei could decondense fully and form pronuclei in the red common carp egg extracts. Gibel carp sperm nuclei could also decondense fully and form pronuclei in the gibel carp egg extracts, but red common carp sperm nuclei could not decondense sufficiently in the same extracts. The significant differences of morphological changes were further confirmed by ultrastructural. observation of transmission electron microscopy. The data further offer cytological evidence for gonochoristic reproduction in the gynogenetically reproducing gibel carp. In addition, the sperm nuclei in vitro decondensation is dependent on the pH in the extracts, and the decondensed efficiency is optimal at pH 7. However, no DNA replication was observed in the two kinds of egg extracts during the incubation period of the sperm nuclei. It is suggested that the egg extracts prepared from the gynogenetic gibel carp should be a valid in vitro system for studying molecular mechanism on gynogenesis and reproduction mode diversity in fish.

Morphological variation of Keratella cochlearis (Rotatoria) in a shallow, eutrophic subtropic Chinese lake

The duration of occurrence of two morphological forms of Keratella cochlearis varied seasonally in Lake Donghu, a shallow eutrophic lake in China. The total lengths of both K cochlearis tecta and K cochlearis cochlearis were negatively correlated with the water temperature. Total length of K cochlearis tecta may also have been influenced by the degree of eutrophication or available food.

Karyotypic diversity in polyploid gibel carp, Carassius auratus gibelio Bloch

Polyploid gibel carp, Carassius auratus gibelio, is an excellent model system for evolutionary genetics owing to its specific genetic background and reproductive modes. Comparative karyotype studies were performed in three cultured clones, one artificially manipulated group, and one mated group between two clones. Both the clones A and P had 156 chromosomes in their karyotypes, with 36 metacentric, 54 submetacentric, 36 subtelocentric, 24 acrocentric, and six small chromosomes. The karyotype of clone D contained 162 chromosomes, with 42 metacentric, 54 submetacentric, 36 subtelocentric, 24 acrocentric, and six small chromosomes. All the three clones had six small chromosomes in common. Group G, being originated from the clone D by artificial manipulation, showed supernumerary microchromosomes or chromosomal fragments, in addition to the normal chromosome complement that was identical to the clone D. The offspring from mating between clones D and A had 159 chromosomes. Comparing with the clone A, the DA offspring showed three extra metacentric chromosomes. In addition, variable RAPD fingerprint patterns and unusual SCAR marker inheritance were, respectively, detected among individuals of artificial group G and in the mated DA offspring. Both the chromosome and molecular findings suggest that genome reshuffling might have occurred by manipulation or mating of the clones.

Floral surveys on Gomphonemaceae and Cymbellaceae (Bacillariophyta) from the headwaters of the Yangtze River, Qinghai, China

Gomphonemaceae and Cymbellaceae from the headwaters of the Yangtze River, Qinghai Province, China, comprised 84 taxa belonging to four genera. The dominant species were Gomphonema kaznakowi Mer., G. hedini Hust., G. olivaceum (Lyngbye) Kutz., Cymbella cistula (Ehr.) Kirchn. var. cistula and C. minuta Hilse ex Rabh. var. minuta. Some arctic and alpine forms also occurred, and the following taxa were unique to this region: C. cistula var. asiatica Mer., C. cistula var. capitata Grun., C. yabe Skvortzow var. punctata Li and Shi, G. olivaceum (Lyngbye) Kutzing var. brevistriatum Li and Shi and G. staurophorum (Pant.) Cleve-Euler var. oblongum Li and Shi. Different morphological forms of G. kaznakowi Mer. may be related to the upheaval of the plateau. Species diversity of the diatoms appears to be related not only to macro-environment (e.g., geographic zonation) but also to microhabitat and microclimate.

Genetic diversity among different clones of the gynogenetic silver crucian carp, Carassius auratus gibelio, revealed by transferrin and isozyme markers

Genetic diversity among four clones (A, D, E, F) of gynogenetic silver crucian carp was studied using transferrin and isozymes in the blood as markers. Of the five proteins investigated, three (transferrin, esterase and superoxide dismutase) indicated polymorphism and eight polymorphic loci were detected. These loci were probably encoded by codominant alleles and their inheritance patterns were analyzed. Intraclonal homogeneity and interclonal heterogeneity were observed in these clones, which allowed us to infer the clonal nature and evolutionary relationship between them. Clonal diversity in this population of silver crucian carp in China was also compared with data reported from gynogenetic crucian carp in Germany.

Dietary-morphological relationships of fishes in Liangzi Lake, China

Species in Liangzi Lake were clustered into four trophic groups: Hemiramphus kurumeus and Hemiculter bleekeri bleekeri fed predominantly on terrestrial insects; Carassius auratus auratus and Abbottina rivularis on non-animal food; Hypseleotris swinhonis, Ctenogobius giurinus, Pseudorasbora parva and Toxabramis swinhonis on cladocerans or copepods; Culterichthys erythropterus on decapod shrimps. Gut length, mouth width, mouth height, gill raker length and gill raker spacing, varied widely among species. With the exception of three species pairs (H. swinhonis, C. glurinus; C. erythropterus, H. kurumeus; T. swinhonis, H. bleekeri bleekeri), principal components analysis of morphological variables revealed over-dispersion of species. Canonical correspondence analysis of dietary and morphological data revealed five significant dietary-morphological correlations. The first three roots explained > 85% of the total variance. The first root reflected mainly the relationship of gut length to non-animal feud, with an increase in gut length associated with an increase in non-animal food. The second root was influenced strongly by the relationship of the gill raker spacing to consumption of copepods, with an increase in gill raker spacing associated positively with copepods in the diet. The third root was influenced by the relationship of mouth gape to consumption of fish and decapod shrimps, with an increase in mouth gape associated with more fish and decapod shrimps in the diet. These significant dietary-morphological relationships supported the eco-morphological hypotheses that fish morphology influence food use, and morphological variation is important in determining ecological segregation of co-existing fish species. (C) 2001 The Fisheries Society of the British Isles.

Diversity of intestinal helminth communities of carp from six lakes in the flood plain of the Yangtze river, China

The infra- and component communities of intestinal helminths of carp Cyprinus carpio were investigated in six lakes in the flood plain of the lower and middle reaches of the Yangtze River, China. Eight species of helminth parasites were recorded. The intestinal helminth communities were species rich in Niushan and Tonghu lakes where the digenean Asymphylodora japonica was the dominant species, whereas in Qinggang and Yanglan lakes a species-poor helminth community had only one species, Khawia sinensis. The degree of similarity within localities was highest in Qinggang and Yanglan lakes, and was high between communities where K. sinensis was the dominant species. The rich composition of these helminth communities may be because China is the heartland for carp while the poor helminth composition of those in Qinggang and Yanglan lakes may reflect the poor fauna there. It is suggested that species compositions of intestinal helminth communities of carp may be diversified in lakes in the hood plain of the Yangtze River. (C) 1999 The Fisheries Society of the British Isles.

The structural, morphological and magnetic characteristics of Mn-implanted nonpolar a-plane GaN films

Dilute magnetic nonpolar GaN films have been fabricated by implanting Mn into unintentionally doped nonpolar a-plane GaN films at room temperature, and a subsequent rapid thermal annealing. The X-ray diffraction analysis shows that after rapid thermal annealing the peak of the GaN X-ray diffraction curve shifts to a lower angle, indicating a slight expansion of the GaN crystal lattice. Atomic force microscopy analysis shows that the annealing process does not change the morphology of the sample greatly. Magnetic property analysis indicates that the as-annealed sample shows obvious ferromagnetic properties. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Structural, morphological, and magnetic characteristics of Cu-implanted nonpolar GaN films

Diluted magnetic nonpolar GaN:Cu films have been fabricated by implanting Cu ions into unintentionally doped nonpolar a-plane(1 1 (2) over bar 0) GaN films and a subsequent thermal annealing process. The structural, morphological and magnetic characteristics of the samples have been investigated by means of high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), and superconducting quantum interference device (SQUID). The sample shows a clear ferromagnetism behavior at room temperature. It is significantly shown that with a Cu concentration as low as 0.75% the sample exhibits a saturation magnetization about 0.65 mu(B)/Cu atom. Moreover, the possible origin of the ferromagnetism for the sample was also discussed briefly. (C) 2009 Elsevier B. V. All rights reserved.

Morphological defects and uniformity issues of 4H-SiC homoepitaxial layers grown on off-oriented (0001)Si faces

The morphological defects and uniformity of 4H-SiC epilayers grown by hot wall CVD at 1500 degrees C on off-oriented (0001) Si faces are characterized by atomic force microscope, Nomarski optical microscopy, and Micro-Raman spectroscopy. Typical morphological defects including triangular defects, wavy steps, round pits, and groove defects are observed in mirror-like SiC epilayers. The preparation of the substrate surface is necessary for the growth of high-quality 4H-SiC epitaxial layers with low-surface defect density under optimized growth conditions. (c) 2006 Elsevier Ltd. All rights reserved.

Influences of reactor pressure of GaN buffer layers on morphological evolution of GaN grown by MOCVD

The morphological evolution of GaN thin films grown on sapphire by metalorganic chemical vapor deposition was demonstrated to depend strongly on the growth pressure of GaN nucleation layer (NL). For the commonly used two-step growth process, a change in deposition pressure of NL greatly influences the growth mode and morphological evolution of the following GaN epitaxy. By means of atomic force microscopy and scanning electron microscope, it is shown that the initial density and the spacing of nucleation sites on the NL and subsequently the growth mode of FIT GaN epilayer may be directly controlled by tailoring the initial low temperature NL growth pressure. A mode is proposed to explain the TD reduction for NL grown at relatively high reactor pressure. (C) 2003 Elsevier B.V. All rights reserved.