Recursos de colección

Hokkaido University Collection of Scholarly and Academic Papers (135.521 recursos)

HUSCAP (Hokkaido University Collection of Scholarly and Academic Papers) contains peer-reviewed journal articles, proceedings, educational resources and any kind of scholarly works of Hokkaido University.

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Mostrando recursos 1 - 20 de 20

  1. Effect of Oxidative Reactions on the Lignin Degradation and Delignification during Chlorine Bleaching of Kraft Pulp

    Koda, Keiichi

  2. 植物葉の光合成に与える粉じんの影響に関する研究

    平野, 高司

  3. Studies on the Freeze Denaturation of Squid Actomyosin

    IGUCHI, Sanae M. M.; TSUCHIYA, Takahide; MATSUMOTO, Juichiro
    Denaturation of squid actomyosin during frozen storage was studied by measuring solubility, viscosity, and ATPase activity, and by ultracentrifugal analysis and SDS-electrophoresis. The additive effect of sodium glutamate, well-known for its cryoprotective effect on the freeze denaturation of carp actomyosin, was also checked. When solutions (0.6M KC1) or suspesions (0.05M KC1) of the isolated squid actomyosin were stored at -20℃, the solubility, reduced viscosity and ATPase activity decreased with the length of frozen storage. The ultracentrifugal patterns showed that aggregation proceeded during frozen storage. Evidently, sodium glutamate prevented the freeze denaturation of squid actomyosin, as in the case of carp...

  4. Different biomass-allocation patterns among four tree species in heavily disturbed sites on a volcanic mountain in Hokkaido, northern Japan

    Shibuya, Masato; Yajima, Takashi; Yoshida, Mihoko; Sasaoka, Eiji
    We have compared biomass-allocation patterns and frequency of sprouting among saplings of four tree species (Larix kaempferi, Betula platyphylla var. japonica, Populus maximowiczii, and Populus sieboldii) growing on a volcanic mountain in Hokkaido, northern Japan. Growing conditions were very harsh on the mountainside. Leaf mass and fine root mass relative to root mass were larger in L. kaempferi, and L. kaempferi root mass was less than for the other species. Sprouting ratios were high for the broadleaved species. Different allometries and sprouting ratios among species suggest that survival strategies for L. kaempferi were different from those for the broadleaved species....

  5. ANATOMICAL CHARACTERISTICS AND MECHANICAL PROPERTIES OF LARIX SIBIRICA GROWN IN SOUTH-CENTRAL SIBERIA

    Koizumi, Akio; Takata, Katsuhiko; Yamashita, Kana; Nakada, Ryogo
    Tracheid length, microfibril angle, spiral grain, wood density, MOE, MOR, compressive strength, modulus of rigidity and their inter-relationships were investigated for fifty Siberian larch trees (Larix sibirica) collected from five natural stands. No inter-stand variation in tracheid length, microfibril angle and spiral grain was observed. No effect of tracheid length and microfibril angle on the mechanical properties was observed. Inter-stand variation in wood density was significant, especially for mature wood. The wood from the Baikal site in the eastern range of the natural distribution had a very high density. The wood from the Altai site in the mountain range had...

  6. Seasonal changes in the photosynthetic capacity of cones on a larch (Larix kaempferi) canopy

    Wang, W. -J.; Watanabe, Y.; Endo, I.; Kitaoka, S.; Koike, T.
    The seasonal changes of photosynthesis of cones of Japanese larch (Larix kaempferi Carr.) trees showed that gross photosynthetic rate of young cones (P G) was 2–3 µmol m−2 s−1 at surface area unit and P G/R D (dark respiration of cones) peaked about 0.7 in the same period, indicating that 70 % of respiratory CO2 was re-fixed. With maturation, P G and P G/R D sharply decreased. Chlorophyll content in cones was 3–20 % of that in leaves, which made it a limiting factor for photosynthesis and its content was closely correlated with photosynthetic capacity. Although sunken and linearly arranged...

  7. Effect of habitat components on competitive interaction between native white-spotted charr and introduced brown trout

    Hasegawa, Koh; Maekawa, Koji
    In salmonid species, interspecific competition has been affirmed as the major mechanism of the replacement of native species by introduced species. However, competitive interactions are variable according to various habitat components. Our study on native white-spotted charr and introduced brown trout in a small creek in southwestern Hokkaido, Japan indicates that the intensity of the interspecific competition was reduced in structurally complex habitats, areas with numerous woody debris, because the native species were able to survive in those environments. Therefore, the replacement may be inhibited in structurally complex habitat.

  8. Responses of macroinvertebrate communities to river restoration in a channelized segment of the Shibetsu River, Northern Japan

    Nakano, Daisuke; Nakamura, Futoshi
    The effects of restoration of channel meandering and of groyne structures on physical variables and river-dwelling macroinvertebrates were examined in a lowland river, the Shibetsu River in Northern Japan. The lowland segment of the Shibetsu River, which previously meandered, was straightened by channelization and groynes installed on some portions of the channelized reach. In 2002, the channelization works were partly reversed to improve the degraded river ecosystem. Physical environment variables and macroinvertebrate community structure and composition were compared among reconstructed meanders and channelized reaches with and without groynes. The shear stress of the river edge in reconstructed meanders and groyne...

  9. Evaluation of the section modulus for tree-stem cross sections of irregular shape

    Koizumi, Akio; Hirai, Takuro
    The effect of section modulus as estimated for tree stems of irregular cross section with hollow trunks on windthrow resistance was discussed. The sample trees were 12 aged poplar trees growing along the roadside in Sapporo. Binarized bitmap images of photographs of the crosscut surface of the sample tree stems were used to calculate numerical solutions for section moduli. The error for image resolution was simulated to less than 1% under the condition in which the image was divided into more than 400 pixels. The coefficient of variation in section modulus concerning six neutral axis directions in a horizontal plane...

  10. The water relation of seedlings of Picea jezoensis on fallen logs

    Iijima, Hayato; Shibuya, Masato; Saito, Hideyuki; Takahashi, Kunihide
    We examined whether fallen logs without moss (FLB) are more drought-stressful sites for Picea jezoensis Carr. seedlings than are logs with moss (FLM) and whether drought affects the mortality of seedlings on logs. We measured the water potential of the log humus layer (Psi(H)) and needles of seedlings on the logs (Psi(N)) in a natural forest and a greenhouse under various drought conditions. We also determined the critical Psi(N) from the relationship between seedling mortality, Psi(N), and chlorophyll fluorescence, Fv/Fm. The Psi(H) on both moss-covered and bare logs in the forest was 0 MPa, regardless of the number of days...

  11. Effects of clear-cutting on nitrogen leaching and fine root dynamics in a cool-temperate forested watershed in northern Japan

    Fukuzawa, Karibu; Shibata, Hideaki; Takagi, Kentaro; Nomura, Mutsumi; Kurima, Noriko; Fukazawa, Tatsuya; Satoh, Fuyuki; Sasa, Kaichiro
    Stream and soil solution chemistry, fine root biomass and soil nitrogen processing before and after clear-cutting of trees and subsequent strip-cutting of understory vegetation, dwarf bamboo (Sasa senanensis), were investigated to understand the effect of these disturbances on biogeochemical processes on forested watershed in northern Japan. Tree-cutting did not cause a significant increase of nitrate (NO3−) concentration in stream water during the growing season after the cutting. Subsequent Sasa-cutting caused significant increase of stream NO3− concentration to ca. 15 μmol L−1. There was no significant change of stream pH following both cuttings. NO3− concentration in soil solution increased after both...

  12. Host defense in Nicrophorus quadripunctatus against brood parasitism by Ptomascopus morio (Coleoptera: Silphidae: Nicrophorinae)

    Suzuki, Seizi; Nagano, Masahiro
    Few studies have been conducted on the host defenses of insects against brood parasitism. We investigated whether the silphid beetle Ptomascopus morio, a brood parasite of related silphid species Nicrophorus concolor, can also parasitize another silphid species Nicrophorus quadripunctatus and the manner in which N. quadripunctatus defends itself against parasitism. Successful brood parasitism under natural conditions was not observed at the time of year when P. morio and N. quadripunctatus are both reproductively active. Follow-up experiments revealed that P. morio attempts to oviposit near N. quadripunctatus nests, but is rarely successful if adult hosts are present. When P. morio larvae...

  13. Multiple host shifts between distantly related plants, Juglandaceae and Ericaceae, in the leaf-mining moth Acrocercops leucophaea complex (Lepidoptera: Gracillariidae)

    Ohshima, Issei; Yoshizawa, Kazunori
    Insect herbivores such as gall formers and leaf miners are often highly specialized and adapted to their respective natal host plants. Due to the specialization and adaptation, it is presumed that host shifts readily occur among closely related plant species. Leaf-mining moths, the Acrocercops leucophaea complex, consist of three species, A. leucophaea, A. defigurata, and A. transecta. Larvae of all the species of the complex feed on Juglandaceae plants, but A. leucophaea and A. transecta are also associated with an Ericaceae plant, which is quite distantly related to Juglandaceae. Such a host utilization as in this species complex is very...

  14. Function of the web box as an anti-predator barrier in the spider mite, Schizotetranychus recki

    Horita, Mituru; Chittenden, Anthony R.; Sato, Yukie; Saito, Yutaka
    Spider mites inhabiting Sasa bamboo show considerable variation in traits believed to be the result of coevolution between predator and prey. In Schizotetranychus recki Ehara inhabiting the hairy leaves of a dwarf bamboo, Sasa senanensis, all quiescent stages, including eggs, appear within web boxes in the leaf hairs of their host plant, and this habit is thought to be a trait involved in predator avoidance. To test this hypothesis, the survival rates of S. recki eggs inside a web box and those freed of a web box were assessed in relation to six predator species that co-occur with the spider...

  15. Inbreeding depression by recessive deleterious genes affecting female fecundity of a haplo-diploid mite

    Saito, Y.; Sahara, K.; Mori, K.
    The effect of inbreeding on haplo-diploid organisms has been regarded as very low, because deleterious recessive genes on hemizygous (haploid) males were immediately purged generation by generation. However, we determined such recessive genes to decrease female fecundity in a population of Schizotetranychus miscanthi Saito which is known in the Acari as a subsocial species with haplo-diploidy. In mother-son inbreeding experiments, there was no depression in egg hatchability nor in the larval survival of progeny over 4 generations. There was, on the other hand, significant inbreeding depression in the fecundity with increasing f-value. Crosses between two lineages, one having deleterious effects...

  16. Variation in social behavior within a spider mite genus, Stigmaeopsis (Acari: Tetranychidae)

    Mori, Kotaro; Saito, Yutaka
    The spider mites belonging to the genus Stigmaeopsis construct extremely dense oval woven roofs (web-nests) over depressions on the lower surface of host leaves and are known to have a kind of sociality. The 4 species that occur on bamboo plants in Japan, show different nest areas. The nest area of Stigmaeopsis longus is the largest, followed by S. celarius, S. takahashii and S. saharai in decreasing order. Smaller nests effectively prevent adults of several predator mite species from intruding. We hypothesized that variation in nest size reflects different anti-intruder adaptations of this mite group in relation to their sociality....

  17. Nest size variation reflecting anti-predator strategies in social spider mites of Stigmaeopsis (Acari: Tetranychidae)

    Mori, Kotaro; Saito, Yutaka
    The social spider mites (Acari: Tetranychidae) of Stigmaeopsis weave dense nests on the underside of host leaves. Four species occur on the leaves of bamboo in Japan: Stigmaeopsis longus, S. celarius, S. takahashii and S. saharai. We initially reconfirmed the occurrence of distinct variation in nest size among the species. Based on the hypothesis that this variation plays a role in protecting the spider mites from predators, we looked at the behavior of the natural enemies that occur on the host plants along with members of Stigmaeopsis. We found considerable variation in the ability of nests to protect the spider...

  18. Where does male-to-male aggression compromise cooperation?

    Saito, Yutaka; Mori, Kotaro
    We discuss how the diverse nature of aggression and cooperation can be understood if we focus our attention on where aggression reaches a compromise with non-aggression and/or cooperation in response to the relatedness between interactors. First we address whether Hamiltons rule explains the variation in male-to-male aggressiveness. Next we show that the variation in aggression and cooperation known in males of social spider mites (Saito, Evolution 49:413–417, 1995) can be explained by the change in relatedness (i.e. inclusive fitness) and effect of cooperative defence (synergistic effect). Then we learn that there is a sufficient condition of cooperation, which is determined...

  19. Marketing Environment of Structural Lumber in Japan

    Owari, Toshiaki
    This paper presents the latest information on the Japanese marketing environment of structural lumber that is used for house construction. The demand for lumber has decreased, while the demand for structural laminated lumber has been rapidly increasing. The changes in end-users’ requirements have created demand for structural laminated lumber. The imports in lumber and structural laminated lumber from Europe have been increasing in Japan. Europe succeeded in meeting the changing end-users’ needs. The distribution system for lumber has been changing a great deal. The emergence of the pre-cut business has sharply reduced the items distributed through conventional routes. The pre-cut...

  20. Intercultural communication in the forest products business in China : a case study

    Owari, Toshiaki
    The growing forest products business in China has attracted foreign companies to the Chinese market. This study examines the unique characteristics of intercultural communication in the forest products business in China, using an exploratory case study approach. In-depth interviews were conducted with executives of a multinational forest industry company. The qualitative data analysis identified ten topics concerning business communication in China: bureaucracy, negotiation, business protocols, personal connections, distribution channel, employee recruitment, employee retention, language, publicity, and donations. The results illustrate the characteristics of business communication and how Western expatriates deal with communication issues in relation to the Chinese. Finally, this...

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