Morphological and toxicity characteristics of Pseudo-nitzschia pungens strain PP0201-01 isolated from the East China Sea

The morphology and toxicity ofPseudo-nitzschia strain PP0201-01, isolated near the estuary of Changjiang (Yangtze) River in Year 2002 and tentatively identified asPseudo-nitzschia pungens, were studied. The strain was identified morphologically asP. pungens using scanning electronic microscope (SEM). The analytical results of LC-PDA (liquid chromatography with photodiode array detector), LC-MS (liquid chromatography with mass detector), and the toxicity data from mouse bioassay, showed that no domoic acid was produced by the strain. However, the mechanism of domoic acid production byPseudo-nitzschia species is complicated. More works are needed to assess the toxic species and to evaluate the potential risk of amnesic shellfish poisoning (ASP) in China. Supported by the projects of Ministry of Science and Technology (No. 2001CB409704 and No. 2001BA804A20), and the innovation project of the Institute of Oceanology, CAS (No. 200223107).     

基于SoC的家庭网关的研究与设计

家庭网关是家庭信息案,设计了一种基于SoC的家庭网关平台,并详细介绍了其开发流程.     

长春双阳地震台数字水管仪倾斜潮汐观测质量评定

对双阳地震台DSQ型水管倾斜仪2001～2006年倾斜潮汐观测资料作了质量评定,检定结果显示:观测资料连续,仪器观测状况稳定,年零漂、年变幅小,噪声水平低.     

DSQ型水管倾斜仪安装中的一些技术问题

讨论了DSQ型水管倾斜仪安装中洞体安装条件、密封保温设施、水管气泡排除、IP标定等应注意的一些技术问题.     

Peat bank growth,Holocene palaeoecology and climate history of South Georgia (sub-Antarctica), based on a botanical macrofossil record

Botanical macrofossil analysis of a more than 9000 years old, radiocarbon dated peat sequence of a moss peat bank from South Georgia, shows a clear evolution in the vegetation. Seven ecological phases could be distinguished and they can be interpreted in terms of climate development during the Holocene. Until 2200 years ago, Warnstorfia fontinaliopsis was the dominant moss species pointing to a wet environment. Lower numbers of this species in association with the presence of drier species are assumed to indicate drier periods, such as occurring between ca 6000–5200 and 4400–3400 cal yr BP. The most prominent and definitive vegetation change took place around 2200 cal yr BP. A Polytrichum–Chorisodontium moss peat bank was formed, which is still growing there today. The forcing mechanism for this vegetation change is thought to be a temperature decrease, rather than a precipitation decrease. This conclusion is mainly based on the fact that, today, moss peat banks have their optimal occurrence range in the maritime Antarctic, a region were the mean annual temperature is ca 4 °C lower than on South Georgia. The remarkable change in the moss bank vegetation at 2200 cal yr BP raises the question whether this moment was only a short climatic deterioration, or a definitive change to a cooler and wetter climate after a Holocene climatic optimum period.     

Quantitative reconstruction of Early Pleistocene climate in southeastern Australia and implications for atmospheric circulation

Today, southeastern Australia experiences a winter-dominated rainfall regime, governed by the seasonal migration of the highly zonal Southern Hemisphere subtropical anticyclone. The late Cenozoic history of this rainfall regime is poorly understood, but it has been widely accepted that its onset was a product of the intensification and northward migration of the subtropical anticyclone, driven by steepening of hemispheric temperature gradients associated with the initiation of extensive Northern Hemisphere glaciation, ～2.6 million years ago (Ma). Here, we use fossil beetle remains from Stony Creek Basin, a small palaeolake record in upland southeastern Australia deposited over ～280,000 years between ～1.84 and 1.56 Ma, to quantitatively reconstruct regional climate during the Early Pleistocene. Climate reconstructions based on coexistence of extant beetle taxa indicate that temperatures were consistently 1–3 °C warmer than present, and rainfall as high as or substantially higher than today, throughout the record. In particular, beetle data indicate that rainfall was similar to today during winter, but 2–2.4 times higher than today during summer. This is consistent with the presence of diverse rainforest pollen also present in the record, and indicates that the modern, winter-dominated rainfall regime was not yet in place by ～1.5 Ma, at least one million years later than previously thought. We suggest that the Southern Hemisphere anticyclonic circulation must have been much less intense during the Early Pleistocene than today, rather than shifted meridionally as previously argued.     

Mesoproterozoic Lakhanda Lagerstätte, Siberia: Paleoecology and taphonomy of the microbiota

The preservation of the organic-walled microbiota of the Lakhanda Lagerstätte in the Kumakha mudstone succession of the late Mesoproterozoic Lakhanda Group (Uchur-Maya region, southeast Siberia) is a result of unusually favorable paleoecologic, taphonomic, and diagenetic conditions. Well known for its marked taxonomic diversity and exquisite preservation, the biota inhabited a warm, shallow, epicontinental basin rich in nutrients into which were dispersed clay minerals, from weathering of continental crust, and minor amounts of volcanic detritus. The fossils were preserved by compression in fine-grained smectite–illite–kaolinite mudstones deposited in a sulfur-deficient disoxic and anoxic environment. Subsequently, the long-term (1 Ga) tectonic stability of the southeast margin of the Siberian platform has provided an exceptional environment for the preservation of the microfossil assemblage without significant diagenetic alteration. Conclusions drawn here from studies of the paleoecology, taphonomy, and diagenesis of the Lakhanda Lagerstätte may provide a globally useful model in the search for additional evidence of the Precambrian rise to dominance of eukaryotes in the Earth's biosphere.     

Further VLA observations of hydrogen deficient stars

VLA observations at 6 cm have been obtained for three hydrogen-deficient objects υ Sgr, V 348 Sgr, and A bell 58. A bell 58 was also observed at 2 cm. Only upper limits to the flux density could be set for these sources. A new radio source at 6 cm was found in the field of υ Sgr. The upper limit for 6 cm flux density of V348 Sgr sets an upper limit to its reddening asE(B–V) ≤ 0.65. The hydrogen deficient planetary nebula A 58 shows much lower radio flux than expected from the infrared-radio flux density relationship of planetary nebulae. National Radio Astronomy Observatory’s Very Large Array is operated by Associated Universities Inc. under contract with National Science Foundation, USA.     

The structure and oscillations of low-mass stars in the presence of a magnetic field

The equilibrium structure and oscillations of a partially degenerate standard model in the presence of a poloidal magnetic field have been studied. The magnetic field in the interior has been matched with an outside dipole field. The effect of magnetic field on the various structural parameters, e.g., mass, central condensation, moment of inertia, and oblateness has been computed for different values of the central degeneracy of the model. We have also studied the effect of magnetic field on radial oscillations of the configuration. A variational formulation is used to compute the changes in the frequency of radial mode of oscillation. It has been shown that the changes in frequency computed for various models using a two-parameter eigenfunction are in fair agreement with the values obtained by using the exact eigenfunction.