Cold ions in the hot plasma sheet of Earth's magnetotail

Most visible matter in the Universe exists as plasma. How this plasma is heated, and especially how the initial non-equilibrium plasma distributions relax to thermal equilibrium (as predicted by Maxwell-Boltzman statistics), is a fundamental question in studies of astrophysical and laboratory plasmas. Astrophysical plasmas are often so tenuous that binary collisions can be ignored, and it is not clear how thermal equilibrium develops for these 'collisionless' plasmas. One example of a collisionless plasma is the Earth's plasma sheet, where thermalized hot plasma with ion temperatures of about 5 x 10(7) K has been observed. Here we report direct observations of a plasma distribution function during a solar eclipse, revealing cold ions in the Earth's plasma sheet in coexistence with thermalized hot ions. This cold component cannot be detected by plasma sensors on satellites that are positively charged in sunlight, but our observations in the Earth's shadow show that the density of the cold ions is comparable to that of hot ions. This high density is difficult to explain within existing theories, as it requires a mechanism that permits half of the source plasma to remain cold upon entry into the hot turbulent plasma sheet.     

Repeated injections of energy in the first 600 ms of the giant flare of SGR 1806-20

The massive flare of 27 December 2004 from the soft gamma-ray repeater SGR 1806-20, a possible magnetar, saturated almost all gamma-ray detectors, meaning that the profile of the pulse was poorly characterized. An accurate profile is essential to determine physically what was happening at the source. Here we report the unsaturated gamma-ray profile for the first 600 ms of the flare, with a time resolution of 5.48 ms. The peak of the profile (of the order of 10(7) photons cm(-2) s(-1)) was reached approximately 50 ms after the onset of the flare, and was then followed by a gradual decrease with superposed oscillatory modulations possibly representing repeated energy injections with approximately 60-ms intervals. The implied total energy is comparable to the stored magnetic energy in a magnetar (approximately 10(47) erg) based on the dipole magnetic field intensity (approximately 10(15) G), suggesting either that the energy release mechanism was extremely efficient or that the interior magnetic field is much stronger than the external dipole field.     

An efficient spatio-temporal data structure for multi version managemeng of engineering drawings

In the engineering database system，multiple versions of a design including engineering drawings should be managed efficiently. The paper proposes an efficient spatial data structure，that is an expansion of the R-tree and HR-tree，for version management of engineering drawings. A novel mechanism to manage the difference between drawings is introduced to the HR-tree to eliminate redundant duplications and to reduce the amount of storage required for the data structurr. Data management mechanism and structural properties of our data structure called the MVR+-tree are described.     

IGFBP-4 is an inhibitor of canonical Wnt signalling required for cardiogenesis

Insulin-like growth-factor-binding proteins (IGFBPs) bind to and modulate the actions of insulin-like growth factors (IGFs). Although some of the actions of IGFBPs have been reported to be independent of IGFs, the precise mechanisms of IGF-independent actions of IGFBPs are largely unknown. Here we report a previously unknown function for IGFBP-4 as a cardiogenic growth factor. IGFBP-4 enhanced cardiomyocyte differentiation in vitro, and knockdown of Igfbp4 attenuated cardiomyogenesis both in vitro and in vivo. The cardiogenic effect of IGFBP-4 was independent of its IGF-binding activity but was mediated by the inhibitory effect on canonical Wnt signalling. IGFBP-4 physically interacted with a Wnt receptor, Frizzled 8 (Frz8), and a Wnt co-receptor, low-density lipoprotein receptor-related protein 6 (LRP6), and inhibited the binding of Wnt3A to Frz8 and LRP6. Although IGF-independent, the cardiogenic effect of IGFBP-4 was attenuated by IGFs through IGFBP-4 sequestration. IGFBP-4 is therefore an inhibitor of the canonical Wnt signalling required for cardiogenesis and provides a molecular link between IGF signalling and Wnt signalling.     

An efficient spatio-temporal data structure for multi version management of engineering drawings

In the engineering database system, multiple versions of a design including engineering drawings should be managed efficiently. The paper proposes an efficient spatial data structure, that is an expansion of the R-tree and HR-tree, for version management of engineering drawings. A novel mechanism to manage the difference between drawings is introduced to the HR-tree to eliminate redundant duplications and to reduce the amount of storage required for the data structure. Data management mechanism and structural properties of our data structure called the MVR -tree are described.     

Identification of UBIAD1 as a novel human menaquinone-4 biosynthetic enzyme

Vitamin?K occurs in the natural world in several forms, including a plant form, phylloquinone (PK), and a bacterial form, menaquinones (MKs). In many species, including humans, PK is a minor constituent of hepatic vitamin?K content, with most hepatic vitamin?K content comprising long-chain MKs. Menaquinone-4 (MK-4) is ubiquitously present in extrahepatic tissues, with particularly high concentrations in the brain, kidney and pancreas of humans and rats. It has consistently been shown that PK is endogenously converted to MK-4 (refs 4-8). This occurs either directly within certain tissues or by interconversion to menadione (K(3)), followed by prenylation to MK-4 (refs 9-12). No previous study has sought to identify the human enzyme responsible for MK-4 biosynthesis. Previously we provided evidence for the conversion of PK and K(3) into MK-4 in mouse cerebra. However, the molecular mechanisms for these conversion reactions are unclear. Here we identify a human MK-4 biosynthetic enzyme. We screened the human genome database for prenylation enzymes and found UbiA prenyltransferase containing 1 (UBIAD1), a human homologue of Escherichia coli prenyltransferase menA. We found that short interfering RNA against the UBIAD1 gene inhibited the conversion of deuterium-labelled vitamin?K derivatives into deuterium-labelled-MK-4 (MK-4-d(7)) in human cells. We confirmed that the UBIAD1 gene encodes an MK-4 biosynthetic enzyme through its expression and conversion of deuterium-labelled vitamin?K derivatives into MK-4-d(7) in insect cells infected with UBIAD1 baculovirus. Converted MK-4-d(7) was chemically identified by (2)H-NMR analysis. MK-4 biosynthesis by UBIAD1 was not affected by the vitamin?K antagonist warfarin. UBIAD1 was localized in endoplasmic reticulum and ubiquitously expressed in several tissues of mice. Our results show that UBIAD1 is a human MK-4 biosynthetic enzyme; this identification will permit more effective decisions to be made about vitamin?K intake and bone health.     

基于减压脱水干燥装置的高浓度切削液废水的处理及回收利用

设计并改进减压脱水干燥装置, 改善金属加工过程中产生的大量切削液废水的处理与回收工艺, 以期达到污水零排放和资源化的目标。实验结果表明, 减压脱水干燥装置对废水中总悬浮物的平均去除率超过99.38%, 对油脂类(n-HEX)、BOD5、COD_Mn、总氮、总磷、铜和锌的平均去除率分别为99.07%, 96.67%, 98.64%, 81.28%, 99.33%, 98.69%和99.79%。另外, 结合臭氧处理可以进一步提高对有机污染物的去除率。与其他处理方法相比, 本装置在处理污水的过程中气味小, 噪音少, 不需要添加大量化学药剂, 占地面积小, 成本较低, 适合大批量地处理高浓度切削液废水。     

青藏高原地表参数的被动微波遥感反演研究

利用被动微波遥感数据TMI和GAMB-Tibet加强观测期的地面观测数据，改进和发展了一个被动微波遥感反演地表温度、土壤湿度和植被含水量的三维查表算法(3-D LUT)，并在青藏高原中部中尺度范围内进行了反演试验．对1998年7月1日的数据进行了个例处理，给出了3个地表参数的空间分布结果．进一步考虑了高原对流云对反演结果的影响，对5个月的TMI数据进行了10天的合成处理，利用合成图像运行算法得到了10天平均的结果．结果显示1998年5～9月5个月的土壤湿度反演结果的时空分布与实际情况符合较好；从选取的几个测站的数据比较看，去云处理后得到的土壤湿度反演结果有了明显改善．