INCIDENCE OF HELMINTH PARASITES IN SHREW MOLES

BRIEF COMMUNICATIO

Piezoelectric Properties and Microstructure of (K,Na)NbO3– KTiNbO5 Composite Lead-Free Piezoelectric Ceramic

We developed a (K,Na)NbO3-based lead-free piezoelectric ceramic with a KTiNbO5 system, (K1−xNax)0.86Ca0.04Li0.02Nb0.85O3−δ–KTiNbO5–BaZrO3–Co3O4–Fe2O3–ZnO (KNN–NTK composite). This KNN–NTK composite exhibits a very dense microstructure, and kp = 0.52, ε33T/ε0 = 1600, and d33 = 252 pC/N. We found that a portion of the KTiNbO5 converted into K2(Ti,Nb,Co,Zn)6O13 and/or CoZnTiO4. We were able to reproducibly prepare granulated powder of KNN–NTK in batches of 100 kg using a spray-dryer. In addition, we performed a detailed investigation of the microstructure of KNN–NTK composite. The results show that a tetragonal and an orthorhombic phase coexist in a main KNN phase over a wide range of 0.56 ≤ x ≤ 0.75. The granular nanodomains of the orthorhombic phase dispersed within the tetragonal matrix in the KNN phase. A maximum value of kp = 0.56 occurred for x = 0.56. The Na fraction x corresponding to maximum kp was also the minimum x required to generate the orthorhombic phase. We conclude that the KNN–NTK composite exhibits excellent piezoelectric properties because of the two-phase coexisting state. This gentle phase transition of KNN–NTK composite seems to be a relaxor, but the diffuseness degree γ = 1.07 suggests otherwise

Evolutionary Innovation by Polyploidy

The preferred conditions for evolutionary innovation represent a fundamental question, but little is known experimentally or theoretically. In this study, we focused on the potential role of polyploidy in the evolution of novel traits. We proposed a simple model and demonstrated that the evolutionary rate of polyploids is similar to more much slower than that of haploids under neutral selection or during gradual evolution. However, experiments using polyploid cyanobacteria demonstrated that the probability of achieving antibiotic resistance increased with the number of chromosomes and implied an optimal number of chromosomes. Then, we investigated the dynamics of the same model on a fitness landscape in which cells should jump over a lethal valley to increase their fitness. The evolutionary rate could be increased in polyploidy, and the optimal number of chromosomes was identified. Further, we proposed that the optimization for evolutionary innovation might determine the number of chromosomes in polyploid bacteria.Comment: 35 pages, 8 figures, 4 table

The Roles of the Cortical Motor Areas in Sequential Movements

The ability to learn and perform a sequence of movements is a key component of voluntary motor behavior. During the learning of sequential movements, individuals go through distinct stages of performance improvement. For instance, sequential movements are initially learned relatively fast and later learned more slowly. Over multiple sessions of repetitive practice, performance of the sequential movements can be further improved to the expert level and maintained as a motor skill. How the brain binds elementary movements together into a meaningful action has been a topic of much interest. Studies in human and non-human primates have shown that a brain-wide distributed network is active during the learning and performance of skilled sequential movements. The current challenge is to identify a unique contribution of each area to the complex process of learning and maintenance of skilled sequential movements. Here, I bring together the recent progress in the field to discuss the distinct roles of cortical motor areas in this process

Compressibility of Liquefied Sand

Laboratory measurement using CCD camera was conducted to trace the sedimentation process of sand grains in a liquefied model layer. The purpose of this measurement was basically intended to obtain a visual evidence of appearance of suspended state in upper part of the liquefied soil. For this purpose, glass bead particles were used as model ground material. The test results prevailed that the glass bead grains were suspended in pore water at the instant when complete liquefaction was brought about to the layer, then they began to settle in the water. The measured pore water kept high value until grains ceased moving. And the moving velocity was far slower than that estimated by Stokes equation for sedimentation of single particle. From these findings, a predicting method was proposed to obtain the compressibility of liquefied sand layer and the continuation time of suspended state of grains

On the Ecology and Distribution of \u3ci\u3eEchinococcus\u3c/i\u3e spp. (Cestoda: Taeniidae), and Characteristics of Their Development in the Intermediate Host. II. Comparative Studies on the Development of Larval \u3ci\u3eE. multilocularis\u3c/i\u3e Leuckart, 1863, in the Intermediate Host

This paper reports the results of a comparative study of the development of the larval Echinococcus multilocularis Leuckart, 1863), and associated tissue reaction in naturally and experimentally infected mammals representing 31 species. The histogenesis of the larval cestode was traced in detail in arvicoline rodents of several species, and interspecific differences were defined. In arvicoline rodents, the developing larva exhibited host-specific characteristics within about a month after infection was established. The tissue reaction in Microtus oeconomus was characterized by the production of a large quantity of detritus around the larva, and by the formation of a thick epithelioid zone. In one subspecies, M. oeconomus innuitus, development of the larva was retarded, and the detrital mass was often calcified; in another, M. oeconomus operarius, the detritus rarely became calcified and the larva proliferated more rapidly. In M. pennsylvanicus, the tissue reaction was minimal, and little detritus was present. The characteristics of the tissue reaction in M. montebelli placed it in an intermediate position between the aforementioned species. In Clethrionomys rutilus, a thin epithelioid zone and an outer zone of loose collagenous fibers composed the adventitial layer; exogenous budding was retarded in this vole. A minimal tissue reaction occurred in Lagurus curtatus. In Lemmus spp., larger cysts were characteristic, but areas of small-cystic proliferation were always present. Similar differences in species or subspecies of Citellus and Dicrostonyx were described. Lesions of alveolar bydatid disease in man also were studied. The invasive growth of the larval cestode in the human liver involves a process comparable to small-cystic proliferation in the natural intermediate hosts. Although the later stages of development of the larval cestode are inhibited in man, exogenous proliferation of vesicles continues for the life of the host. The lesion in man was compared with a morphologically similar formation produced by anomalous development of the larval E. granulosus in the bovine liver. The latter is distinguished by the absence of areas of small-cystic proliferation. Non-echinococcal lesions found in the tissues studied, some of which resembled foci caused by the larval E. multilocularis, were briefly discussed