Constructive understanding and reproduction of functions of gluteus medius by using a musculoskeletal walking robot

Several factors affect the performance of humanoid walking. One factor is the complex nature of lower limbs, especially the muscles around the pelvis that contribute significantly to the stability and adaptivity of humanoid locomotion. The significance of this muscle group assures a impact on the facility of walking robots once the nature of its contribution is understood, and it can be replicated on robots. To propose a mechanical structure that facilitates walking in robots, we realized a muscle by modeling its pelvis region like that of a humanoid and developing a musculoskeletal humanoid robot. Especially, we focused on the gluteus medius, which is important for the general stability against frontal movements of the hip. Furthermore, it passively changes its influence on such motions; this is helpful during the different phases of locomotion. These changes depend on the alignment of the pelvis and femur. We confirmed the viability of the robotic gluteus medius, which was simplified to a model of two partial muscles by accomplishing the walking using this robot. This accomplishment verifies our hypothesis that using this model, the supporting functionality for the locomotion of the muscle can be reproduced and enhances the biological plausibility.     

Water Sorption-Desorption Characteristics of Proton-Conducting Antimonic Acids with Cubic and Monoclinic Structures

Protonic conductivities of cubic and monoclinic antimonic acids are known to depend on water vapor pressure. Their water sorption-desorption characteristics are compared and discussed with the water sorption isotherms and the desorption spectra of H₂¹⁶O, D₂O, and H₂¹⁸O. The cubic antimonic acid contains more water than the monoclinic acid, which can be attributed to the existence of micropores in the cubic (pyrochlore type) structure.     

Preparation of aminoalkyl celluloses and their adsorption and desorption of heavy metal ions

Aminoalkyl celluloses (AmACs) were prepared from 6-chlorodeoxycellulose and aliphatic diamines H₂N(CH₂)_mNH₂ (m = 2, 4, 6, 8). Their adsorption and desorption of divalent heavy metal ions such as Cu²⁺, Mn²⁺, Co²⁺, Ni²⁺ and their mixtures were also investigated in detail. Adsorption of metal ions on AmACs was remarkably affected by the pH of the solution, the metal ion and its initial concentration, and also the number of methylene units in the diamines. No adsorption of metal ions occurred on AmACs in strongly acidic solutions. However, metal ions were adsorbed rapidly on AmACs from weakly acidic solutions and the amount of adsorption increased with increasing pH. The effectiveness of AmACs as adsorbents decreased with increasing length of the methylene moiety, and AmACs from ethylenediamine (m = 2) was most effective. The adsorption of metal ions on AmACs was in the order Cu²⁺ > Ni²⁺ > Co²⁺ > Mn²⁺. Accordingly, their behavior followed the Irving-Williams series and Cu²⁺ ions were preferentially adsorbed from solutions containing metal ion mixtures. The adsorbed ions were easily desorbed from the AmACs by stirring in 0.1 M HCl.     

The low-temperature performance of NOx storage and reduction catalyst

The catalytic performance and the behavior of NO_x storage and reduction (NSR) over a model catalyst for lean-burn gasoline engines have been mainly investigated and be discussed based on the temperature and reducing agents use in this study. The experimental results have shown that the NO_x storage amount in the lean atmosphere was the same as the NO_x reduction amount from the subsequent rich spike (RS) above the temperature of 400 °C, while the former was greater than the latter below the temperature of 400 °C. This indicated that when the temperature was below 400 °C compared with the NO_x storage stage, the reduction of the stored NO_x is somehow restricted. We found that the reduction efficiencies with the reducing agents decrease in the order H₂ > CO > C₃H₆ below 400 °C, thus not all of the NO_x storage sites could be fully regenerated even using an excessive reducing agent of CO or C₃H₆, which was supplied to the NSR catalyst, while all the NO_x storage sites could be fully regenerated if an adequate amount of H₂ was supplied. We also verified that the H₂ generation more favorably occurred through the water gas shift reaction than through the steam reforming reaction. This difference in the H₂ generation could reasonably explain why CO was more efficient for the reduction of the stored NO_x than C₃H₆, and hinted as a promising approach to enhance the low-temperature performance of the current NSR catalysts though promoting the H₂ generation reaction.     

Some aspects of nonisothermal crystallization of polymers. II. Consideration of the isokinetic condition

In the previous paper a practical method has been applied for an analysis of non-isothermal crystallization in terms of data of isothermal crystallization. The fundamental equation was written on the assumption of the isokinetic conditions in the following form: where X(t) is the degree of phase transformation at time t, and n is the Avrami index determined in the isothermal experiments; K(T) is connected with the crystallization rate constant of the isothermal crystallization, k(T), through the relation K(T) = k(T)^1/n. The equation is derived on the basis of the well-known theory of phase transformation. Experiments of nonisothermal crystallization of high-density polyethylene were carried out under various cooling conditions. The change in crystallinity during the process was followed by using the above equation in the course of the primary crystallization. A procedure of the analysis of the whole, including both the primary and secondary processes, is suggested as an eminently practical one on a more general assumption.     

Influence of system operation method on CO2 emissions of PV/solar heat/cogeneration system

A PV/solar heat/cogeneration system is assumed to be installed in a hotel. The system is operated with various operation methods: CO₂ minimum operation, fees minimum operation, seasonal operation, daytime operation, and heat demand following operation. Of these five operations, the former two are virtual operations that are operated with the dynamic programming method, and the latter three are actual operations. Computer simulation is implemented using hourly data of solar radiation intensity, atmospheric temperature, electric, cooling, heating, and hot water supply demands for one year, and the life‐cycle CO₂ emission and the total cost are calculated for every operation. The calculation results show that the two virtual and the three actual operations reduce the life‐cycle CO₂ emission by 21% and 13% compared with the conventional system, respectively. In regard to both the CO₂ emission and the cost, there is no significant difference between the two virtual operation methods or among the three actual operation methods. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(2): 54–63, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20414     

The effects of the trophic level on the stability of food webs

The study of food webs has long been a central topic of ecological research, but the structural effects of trophic level on their stability are still not clear. The work described here addresses the influence of a restriction arising from the trophic level on the network topology of food webs which affects their global behavior. We propose a network model of food webs in which the degree of the effects of the trophic level on speciation can be adjusted continuously by a single parameter. The restriction limits the number of species at each level and the establishment of prey-predator relationships between distant levels. Experimental results show that the restriction contributes to the stability of the ecosystem. This is because the strong restriction keeps less robust species at the lower levels abundant by making the distribution of the number of species at each level flat, while the distribution became an inverse pyramidal structure without the restriction. On the other hand, we found that several features of the network, such as the power-law distribution of coextinction sizes and the number of predators, do not depend on the degree of restriction. We also show several comparisons of the experimental data with empirical data in the fossil records.     

Saltiness and Acidity: Detection and Recognition Thresholds and Their Interaction Near the Threshold

ABSTRACT:  Interaction of saltiness and acidity at the threshold level was studied employing 35 to 40 young female panelists. As a 1st step, the detection and recognition thresholds of salt, rice vinegar, and rice black vinegar have been measured for each panelist. To investigate the above interaction, the thresholds have been again measured for each panelist of salt, but this time, vinegar at half the concentration of each panelist's detection threshold was added to the salt solution. Similar measurement has been performed for vinegars with salt at half the concentration of each panelist's detection threshold. The data analysis has been done in 2 ways, namely, (1) by using Student's t -test to detect the significant difference in average between the data with and without the added ingredient and (2) detecting significant deviations from zero in the individual shifts in 2 sensory tests among panelists who participated in the 2 measurements. In doing that, a conversion of the scale was necessary to correct the systematic skewness existing in the original data. As a result, both the detection and recognition thresholds of salt were decreased with the existence of the added vinegar ingredient ( P < 0.001). This tendency was more pronounced with rice black vinegar than with rice vinegar. On the contrary, no significant changes in the threshold of both detection and recognition were observed when salt at the half concentration of the detection threshold was added to rice vinegar. The interaction therefore was found to be asymmetric.     

Review of Functional Studies of Beverage Components Acting on the Recombinant GABAA Neuroreceptor, and Na+/Glucose Cotransporter-Response Using the Xenopus Oocyte Expression System and Electrophysiological Measurements

Beverages such as teas, coffee, cacao, and liquors are produced in large quantities and consumed all over the world. Natural components from beverages affect neurotransmitter receptors, especially the GABA_A receptors, which are involved in defining mental state and therefore have role in stress management in modern society. These components of beverages modulating the responses of GABA_A receptors or other neurotransmitter receptors that affect mental state linked to stress and mood can easily be detected by expressing the receptors in Xenopus oocytes and making voltage-clamp electrophysiological measurements. This approach could be extended to detect food-components, which are functionally active on various transporters such as Na⁺/glucose cotransporters operating in the small intestines to transport glucose into blood, which are inhibited by (+)-catechin and its derivatives in teas. Using this technique, it has become apparent that beverages for stress and mood management must have long-chain normal alcohols but short-chain esters, and phenol derivatives having low numbers of OH^- or phenol groups in addition to fragrant compounds such as geraniol, linalool, cis-jasmone, methyl jasmonate, 1-octen-3-ol, myrcenol, terpinen-4-ol and ethyl phenyl propanoate. The technique could also be used easily to assess the toxicity of food-components to cells, as was reported for saponin and tannic acid which produce large electrical responses in the oocyte. Further, (+)-catechin and its derivatives, and aqueous extracts of coffee, green tea, oolong tea and black tea, dose-dependently produce nonspecific currents, suggesting that high concentrations of these beverages may be detrimental to health.