A Quantitative Analysis of Energy Dissipation among Three Typical Air Entrainment Phenomena

This study investigates energy dissipation due to air bubble entrainment for three typical phenomena; a hydraulic jump, a 2-D vertical plunging jet and a vertical circular plunging jet into water. A simple model is presented here which enables to estimate the energy transformation and dissipation achieved by air bubbles quantitatively for three above phenomena. The average rate of energy dissipation by air bubbles obtained from the experimental data are 25%, 1.4%, and 2.15% with respect to total energy loss for the hydraulic jump, 2-D vertical plunging jet and vertical circular plunging jet, respectively.     

Courtship in fast water currents by a male stream goby ( Rhinogobius brunneus) communicates the parental quality honestly

The stream goby Rhinogobius sp. DA (dark color type) shows exclusive paternal care of the eggs. Males court females in the stream current and previous field observations suggest that females favor males that perform their courtship display in faster water currents, and that such males may have high parental ability because of good physical condition. To validate these observations we examined female choice under controlled laboratory conditions. Mate choice experiments indicated clearly that females preferred males that courted in the faster currents, whereas neither sexually different morphological traits, such as body size, nor the water current alone were important. The experiments with food supply treatments indicated that only males of high physical condition are able to court in the fast currents. Furthermore, males that courted in the fast currents achieved good egg survival, whereas males that were unable to court in the currents did not, due to cannibalism of their egg clutch. Thus, the maximum speed of the water current in which a male courts should be indicative of his quality and of the subsequent survival of eggs under his care. We conclude that Rhinogobius sp. DA females utilize the male courtship display in the water current as an honest indicator of parental quality.Communicated by K. LindströmAn erratum to this article can be found at     

Degree-day accumulation controlling allopatric and sympatric variations in the sociality of sweat bees, <Emphasis Type="Italic">Lasioglossum</Emphasis> (<Emphasis Type="Italic">Evylaeus</Emphasis>) <Emphasis Type="Italic">baleicum</Emphasis> (Hymenoptera: Halictidae)

Halictine bees exhibit a wide range of social behaviour that varies both inter- and intraspecifically. Although previous studies suggested that the intraspecific variation might be attributed to temperature differences, there was no direct evidence to detect the relationships between temperature and socialities. Lasioglossum (Evylaeus) baleicum exhibited solitary behaviour in a cooler locality (Kawakita) because of the shorter breeding season; in a warmer locality (Nishioka Park), however, this bee species exhibited eusociality at sunny site and solitary behaviour at shady site, whereas a molecular phylogeny confirms that all of these colonies are evidently conspecific. Therefore, we examined the effect of degree-day accumulation on the sympatric social variation of L. baleicum by rearing the bees to calculate the threshold temperature. Whereas they showed high mortality, the threshold temperature was estimated to be 10.33°C and the expected degree-day accumulation was 340 degree days. When we use this value of a degree-day accumulation to estimate the expected eclosion date, the estimated dates were always consistent with observed eclosion dates. In any sites where the bees were solitary, the degree-day accumulation was not enough for the second eclosion by the end of the bee-active season. In Nishioka Park, sex ratio of the first brood was female biased, and daughters were smaller than mothers; in Kawakita, however, there was no sex bias, and daughters were as large as their mothers indicating that the foundresses seem to produce gyne-sized females in Kawakita but worker-sized females in Nishioka though these females do not become workers at shady site.     

Paraben-chlorinated derivatives in river waters

This article reports the first identification of paraben-chlorinated derivatives in river water. Parabens are widely used as preservatives in pharmaceuticals and personal care products. Parabens can be easily chlorinated by chlorinated tap water. The resulting chlorinated derivatives might pose a higher potential risk to humans and ecosystems than the corresponding parent parabens. However, the occurrence of such derivatives in rivers remains unknown so far. We studied 23 parabens and their chlorinated derivatives from rivers receiving effluents from sewage treatment plants in Shizuoka city, in the central Pacific region of Japan. The compounds were extracted by solid-phase extraction with a styrene polymer sorbent, trimethylsilyl-derivatized, and then identified by gas chromatography–mass spectrometry. Six chlorinated parabens and their primary degradation products, two chlorinated hydroxybenzoic acids, were found for the first time in river water. Moreover, in river water, chlorinated derivatives preferentially partition into the suspended-solid phase.     

《安全生产法》修订需要重点解决的若干问题研究

分析我国《安全生产法》的贯彻实施情况,总结《安全生产法》实施过程中面临的政府安全生产监管机构职责分工调整、各级安全生产监管部门职责不清和运行不畅、新型的责任保险出现、企业安全生产主体责任不能完全落实等新形势和挑战。为适应我国快速发展的社会环境,以职业安全与健康立法一体化、安全生产监督与管理权限划分、工伤保险与责任保险结合、强化企业安全生产主体责任等难点为重点,提出《安全生产法》相关条款的修订建议、理由和内容。研究结果对完善我国《安全生产法》,提升安全生产法制化水平具有参考意义。     

Mercury volatilization by the most mercury-resistant bacteria from the seawater of Minamata Bay in various physiological conditions

The volatilization of mercuric chloride (HgCl₂) and methyl mercuric chloride (CH₃HgCl) by the 45 strains (35 Pseudoalteromonas sp., 2 Vibrio sp., 1 Aeromonas sp., and 7 unclassified) of the most mercury-resistant bacteria from Minamata Bay seawater was examined in various physiological conditions. The bacteria could grow and volatilize HgCl₂ in the liquid medium containing 1-10% NaCl. Two Pseudoalteromonas strains could grow and volatilize HgCl₂ at pH levels ranging from 5.0 to 10.0. The resting cells of 43 strains could volatilize HgCl₂ at concentrations ranging from 30 to 68% after 1-h incubation at 30vv°C. The resting cells of 41 strains could volatilize CH₃HgCl at concentrations ranging from 13 to 88% after 1-h incubation at 30vv°C. Ninety-two percent of mercury was removed from the phosphate buffer containing 0.1 7g/ml by a resting cell of Pseudoalteromonas strain H-4 after 30-min incubation at 30vv°C. We were able to screen the special bacteria, which could volatilize mercury compounds at a high rate in various physiological conditions, for the purpose of developing mercury removal methods using bacteria.     

Growth and reproductive biology of the small penaeid shrimp Trachysalambria curvirostris in Tokyo Bay

We investigated the growth and reproductive biology of the penaeid shrimp Trachysalambria curvirostris in Tokyo Bay, Japan, by monthly bottom-trawl surveys from May 2002 to December 2004. We also examined oogenesis in T. curvirostris by histological observation of the ovary. Females grew faster and attained a larger body size for age than males. The growth rate was high in summer and low in winter and was likely to be associated with seasonal changes in water temperature. The carapace length (CL) at which 50% of females contained vitellogenic oocytes was estimated to be 17.0 mm. The reproductive season extended from May to October. Young-of-the-year appeared in October and could be traced across the months on CL histograms to the following September or October, indicating a 1-year life cycle. This extended reproductive season, together with our observation of asynchronous development of oocytes in the ovary, suggests that multiple spawning by individual females may occur during the reproductive season. Postovulated oocytes were not found among the samples we collected during the daytime, suggesting that final oocyte maturation and spawning occur at night. Cortical crypts in the cytoplasm of the oocyte, considered to be a general feature of oogenesis in penaeid shrimps, were not found in T. curvirostris, even in oocytes undergoing germinal vesicle breakdown. This result implies that the cortical reaction after spawning of T. curvirostris may be different from that of other penaeid shrimps.     

Absorption of atmospheric phenol by various tree species and their tolerance to phenol

To assess the effect of tree planting on atmospheric phenol, a study was made on the absorption of phenol by various tree species and the tolerance of these species to phenol. The absorption rates ranged from 21.3 (camellia) to 129 ng dm^‐2h^‐1 ppb^‐1 (Japanese elm) at 1000 μmol of photons m^‐2 s^‐1, and the absorption rate increased in the following order: coniferous tree species ? evergreen broad‐leaved tree species < deciduous broad‐leaved tree species. When the light intensity was varied, a linear relationship between the phenol absorption rate and the transpiration rate was observed for three tree species. In comparison with the absorption rate estimated from a simplified gas diffusive resistance model, we conclude that phenol is absorbed through the stomata and is metabolized fairly rapidly within the leaf tissue, although the absorption rate is less than the estimated potential absorption rate. At phenol concentrations below 200 ppb, the tree can absorb atmospheric phenol for at least 8 h without any visible foliar injury. Trees in general could act as an important sink for atmospheric phenol at phenol concentrations less than 200 ppb, a concentration about twenty times higher than normal ambient levels.