A collision in 2009 as the origin of the debris trail of asteroid P/2010 A2

The peculiar object P/2010?A2 was discovered in January 2010 and given a cometary designation because of the presence of a trail of material, although there was no central condensation or coma. The appearance of this object, in an asteroidal orbit (small eccentricity and inclination) in the inner main asteroid belt attracted attention as a potential new member of the recently recognized class of main-belt comets. If confirmed, this new object would expand the range in heliocentric distance over which main-belt comets are found. Here we report observations of P/2010?A2 by the Rosetta spacecraft. We conclude that the trail arose from a single event, rather than a period of cometary activity, in agreement with independent results. The trail is made up of relatively large particles of millimetre to centimetre size that remain close to the parent asteroid. The shape of the trail can be explained by an initial impact ejecting large clumps of debris that disintegrated and dispersed almost immediately. We determine that this was an asteroid collision that occurred around 10 February 2009.     

The analysis of the Earth co-orbital motion of Chang’e-2 after asteroid flyby

After the Chang’e-2 spacecraft conducted a successful asteroid flyby,where is it flying to in interplanetary space?This question is answered via an introduction to the Chang’e-2’s flight trajectory after asteroid flyby that is termed Earth co-orbital motion.Based on preliminary analysis using the dynamical systems theory,Poincare′sections concept,and routine optimization techniques,it is now predicted that,from the point of view of orbital mechanics,Chang’e-2 is capable of returning to the vicinity of the Earth in no more than 20 a and might be recaptured by the Earth if appropriate orbital maneuvers are going to be exerted,either by itself or by another spacecraft that captures Chang’e-2.     

A Potential Approach of Internet Worm Propagation Based on P2P

Various kinds of active worms have been plunging into the network flows, which make the Internet security problem more serious. Our research on a potential propagation approach of active worms, P2P-based propagation approach, is given in this paper. To measure the propagating performance of our approach, the SEI （Susceptible-Exposed-Infected） propagation model is presented. It proves that with the idea of pure P2P architecture, worms can be hidden in the early stage of propagation, and then infect most of the hosts in a shorter period. By comparing our SEI propagation model with the Simple Epidemic Model, we observe that the size of a worm is a significant parameter which can affect the propagating performance. When the size of the worm becomes large, our approach can still show an excellent propagating performance.     

S100A8 mediates the activation of P65/HLA-B/S100A8/BCL-2/Caspase-9 (-3) pathway in laryngeal carcinogenesis

S100 calcium binding protein A8 (S100A8),a possible novel member of NF-kappa B signal pathway in laryngeal squamous cell carcinoma (LSCC),interacts with human leukocyte antigen B (HLA-B) which carries an NF-kappa B binding site within the enhancer A. The objective of this study was to explore the molecular mechanism of S100A8 in laryngeal carcinogenesis. RT-PCR,Western blotting and immuno-histochemistry staining were applied to evaluate the expression levels of IKKα,P65,REL-B,S100A8,APAF-1 and BCL-2 genes. The signal transduction passway in which S100A8 might participate was explored by RNA interference. Flow cytometry,TUNEL assay and cell invasion in vitro were used to detect the biological behavior of Hep2 cells induced by S100A8 gene. Our results showed that high expression of S100A8 was related to tumorigenesis in LSCC and negatively correlated with the degree of differentiation,indicating that S100A8 gene could inhibit apoptosis and promote metastasis in LSCC. Additionally,the suppression of S100A8 by RNA interference down-regulated BCL-2 but not APAF-1,P65 and IKKα,while,the suppression of P65 could significantly down-regulate the expression of S100A8 gene. In conclusion,S100A8 plays an important role in P65/HLA-B/S100A8/BCL-2/Caspase-9 (-3) pathway in laryngeal carcinoma.     

S 100A8 mediates the activation of P65/HLA- B/S 100A8/BCL-2/Caspase-9 （-3） pathway in laryngeal carcinogenesis

S100 calcium binding protein A8 （S100A8）, a possible novel member of NF-kappa B signal pathway in laryngeal squamous cell carcinoma （LSCC）, interacts with human leukocyte antigen B （HLA-B） which carries an NF-kappa B binding site within the enhancer A. The objective of this study was to explore the molecular mechanism of S100A8 in laryngeal carcinogenesis. RT-PCR, Western blotting and immunohistochemistry staining were applied to evaluate the expression levels of IKKα, P65, REL-B, S100A8, APAF-1 and BCL-2 genes. The signal transduction passway in which S100A8 might participate was explored by RNA interference. Flow cytometry, TUNEL assay and cell invasion in vitro were used to detect the biological behavior of Hep2 cells induced by S100A8 gene. Our results showed that high expression of S100A8 was related to tumorigenesis in LSCC and negatively correlated with the degree of differentiation, indicating that S100A8 gene could inhibit apoptosis and promote metastasis in LSCC. Additionally, the suppression of S100A8 by RNA interference down-regulated BCL-2 but not APAF-1, P65 and IKKα, while, the suppression of P65 could significantly down-regulate the expression of S100A8 gene. In conclusion, S100A8 plays an important role in P65/HLA-B/S100A8/BCL-2/Caspase-9 （-3） pathway in laryngeal carcinoma.     

Is the polydispersity exponent of the hyperbranched polymers the 3/2 or 5/2？

Dendrimers and hyperbranched polymers have re- ceived much attention in recent decade due to their novel physical and chemical properties, such as multi- ple end groups, high solubility, and reduced viscosities relative to their linear counterparts, and h…     

Water-vapor source shift of Xinjiang region during the recent twenty years

The aim of this paper is to investigate the climate water-vapor sources of Xinjiang region and their shifts during the past 20 years. First, the principle and steps are roughly regulated to seek the water-vapor sources. Second, the climate stationary water-vapor transport in troposphere is calculated to distinguish where the water vapor comes from by ERA-40 reanalysis. In addition, the collocation between the transport and the atmospheric column water vapor content is analyzed. The results show that the major vapor comes from the west side of Xinjiang for mid-month of seasons, apart from July while the water vapor comes from the north or northwest direction. The water vapor sources are different for different seasons, for example, the Caspian Sea and Mediterranean are the sources in January and April, the North Atlantic and the Arctic sea in July, and the Black Sea and Caspian Sea in October, respectively. In recent ten years more water vapor above Xinjiang comes from the high latitudes and the Arctic sea with global warming, and less from Mediterranean in comparison with the case of 1973—1986. In fact, the air over subtropics becomes dry and the anomalous water vapor transport direction turns to west or southwest during 1987—2000. By contrast, the air over middle and high latitudes is warmer and wetter than 14 years ago.     

Water-vapor source shift of Xinjiang region during the recent twenty years

The aim of this paper is to investigate the climate water-vapor sources of Xinjiang region and their shifts during the past 20 years. First, the principle and steps are roughly regulated to seek the water-vapor sources. Second, the climate stationary water-vapor transport in troposphere is calculated to distinguish where the water vapor comes from by ERA-40 reanalysis. In addition, the collocation between the transport and the atmospheric column water vapor content is analyzed. The results show that the major vapor comes from the west side of Xinjiang for mid-month of seasons, apart from July while the water vapor comes from the north or northwest direction. The water vapor sources are different for different seasons, for example, the Caspian Sea and Mediterranean are the sources in January and April, the North Atlantic and the Arctic sea in July, and the Black Sea and Caspian Sea in October, respectively. In recent ten years more water vapor above Xinjiang comes from the high latitudes and the Arctic sea with global warming, and less from Mediterranean in comparison with the case of 1973—1986. In fact, the air over subtropics becomes dry and the anomalous water vapor transport direction turns to west or southwest during 1987—2000. By contrast, the air over middle and high latitudes is warmer and wetter than 14 years ago.     

New proofs of the recent climate warming over the Tibetan Plateau as a result of the increasing greenhouse gases emissions

The Tibetan Plateau (TP, 75-105oE, 27.5-37.5oN) is the highest and largest highland in the world with a variety of climate and ecosystems. The TP exerts pro- found influences not only on the local climate and en- vironment but also on the global atmospher…     

Endocasts—the direct evidence and recent advances in the study of human brain evolution

Brain evolution is one of the most important aspects of human evolution, usually studied through endocasts. Analysis of fossil hominid endocasts allows inferences on functional anatomy, physiology, and phylogeny. In this paper, we describe the general features of endocast studies and review some of the major topics in paleoneurology. These are: absolute and relative brain size evolution; brain shape variation; brain asymmetry and lateralization; middle meningeal vessels and venous sinuses; application of computed tomography and virtual imaging; the history of Chinese brain endocast studies. In particular, this review emphasizes endocast studies on Chinese hominin fossils.     

Endocasts—the direct evidence and recent advances in the study of human brain evolution

Brain evolution is one of the most important aspects of human evolution,usually studied through endocasts.Analysis of fossil hominid endocasts allows inferences on functional anatomy,physiology,and phylogeny.In this paper,we describe the general features of endocast studies and review some of the major topics in paleoneurology.These are:absolute and relative brain size evolution;brain shape variation;brain asymmetry and lateralization;middle meningeal vessels and venous sinuses;application of computed tomography and virtual imaging;the history of Chinese brain endocast studies.In particular,this review emphasizes endocast studies on Chinese hominin fossils.     

Unfolding of C2A Domain of Synaptotagmin I in the Presence of Guanidine Hydrochloride

The C2 domain originally referred to the second of four constant structural motifs in protein kinase C (PKC). Now this domain represents a large structural family sharing a homologous dimensional structure in many proteins that play important roles in many organisms. The C2A domain is one of the two C2 domains of synaptotagmin I involved in the Ca^2 regulation of exocytosis. This domain is mostly composed of β-sheet except for a small fraction of α-helix, and therefore provides an ideal model for a protein folding study. In this report, the unfolding equilibrium of the C2A domain in guanidine hydrochloride (GdnHCI) containing solutions has been studied using ultraviolet (UV) difference spectrum, fluorescence spectrum, size exclusion chromatography (SEC), and circular dichroism (CD) spectrum. The results suggest that unfolding of the C2A domain occurs as a two-state process during GdnHCI titration. By examining the changes of both tertiary structure and secondary structure, no intermediates could be detected during this unfolding study. However, it has been found that the native state of the C2A domain has a large hydrophobic surface. This result suggests that as a fragment of a protein, the C2A domain itself may exist in a state with large hydrophobic surface. This hydrophobic surface may be the molecular basis for interaction between domains in the whole protein.Furthermore, the hydrophobic behavior may play a role during the oligomerization of svnaptotagmin.     

Simulation of the future change of East Asian monsoon climate using the IPCC SRES A2 and B2 scenarios

In this paper, we applied the newest emission scenarios of the sulfur and greenhouse gases, i.e. Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES) A2 and B2 scenarios, to investigating the change of the East Asian climate in the last three decades of the 21st century with an atmosphere-ocean coupled general circulation model. The global warming enlarges the land-sea thermal contrast and, hence, enhances (reduces) the East Asian summer (winter) monsoon circulation. The precipitation from the Yangtze and Huaihe river valley to North China increases significantly. In particular, the strong rainfall increase over North China implies that the East Asian rainy area would expand northward. In addition, from the southeastern coastal area to North China, the rainfall would increase significantly in September, implying that the rainy period of the East Asian monsoon would be prolonged about one month. In July, August and September, the interannual variability of the precipitation enhances evidently over North China, meaning a risk of flooding in the future.     

A Trust Scheme Based DRM Model for P2P System

0 IntroductionP2P architectureis a distributed network model ,whichisindependent of server[1]. However , at present , P2Ptechnologyisinfamous for copyright infringement .In P2Par-chitecture,“No-government”may be a seedbed of pirate,vi-rus andillegal resource. Recently there are a large number oflitigations relational to P2P network in American. Napstercaseis the most famous copyright lawsuit of its biggest scaleand most infection[2 ,3].DRM(Digital Right Management) technology is i mpo…     

Reconstruction of the most recent common ancestor sequences of SARS-Cov S gene and detection of adaptive evolution in the spike protein

The genome organization and expression strategy of severe acute respiratory syndrome coronavirus (SARS-CoV) have been described extensively. As a structural glycoprotein on the virion surface, the spike protein is responsible for binding to host cellular receptors and for the fusion between the viral envelope and the cellular membrane. It also induces neutralizing antibodies in     

面向电子商务的P2P发布/订阅系统

当前的电子商务(E-commerce)大多采用传统的B/S结构,同时向用户提供站内的搜索引擎,但事实上电子商务的资源很多时候是分散并且动态的,因此造成了网络拥堵、可靠性低和使用不便等问题。针对上述问题,提出将电子商务迁移到P2P网络环境下,并使用发布/订阅系统代替搜索引擎,以适应网络资源分散和动态的特点。在现有的发布/订阅系统中融入基于内容的多权值过滤算法,提高了系统的性能和信息反馈准确率。数值实验表明:改进的系统将使商业模式更加人性化,网络负载更加平衡,具有更强的鲁棒性。     

Two forms of the membrane-bound state of the first C2 domain (C2A) of synaptotagminⅠand calcium-triggered membrane insertion

The synaptic vesicle protein synaptotagmin I(syt I) is a vesicle transmembrane protein present in synaptic vesicles, which has been proposed as the Ca^2 sensor that regulates secretion. The C2A domain is the membrane proximal part of its cytoplasmic domain. The interaction between C2A and lipid bilayer has been considered to be essential for triggering neurotransmitter release. In the present work, the measurements of membrane surface tension and surface concentration showed that the C2A domain of syt I exhibited two membrane-bound states: the surface adsorption state and the membrane insertion state. The surface absorption state formed in a Ca2~-independent manner with lower affinity, while the membrane insertion state formed with high affinity was only found in the presence of Ca^2 . Both the Ca^2 -independent and Ca^2 -dependent syt I membrane interactions required anionic phospholipids, such as phosphatidylserine (PS). When expressed into rat pheo-chromocytoma (PC12) cells and human embryonic kidney (HEK-293) cells, as demonstrated by immunofluorescence staining and subcellular fractionation, most of the C2A was found at the plasma membrane, even when the cells weredepleted of Ca^2 by incubation with EGTA. These resultssuggested a new molecular mechanism of syt I as a Ca^2 sensor in membrane fusion. Ca^2 -independent surface adsorption might attach syt I to the release site during the docking or priming step. When intracellular Ca^2 increased,syt I triggered the neurotransmitter release following the Ca^2 -dependent penetration into the target membrane.     

Investigation of the kinetic mechanism of the demanganization reaction between carbon-saturated liquid iron and CaF2-CaO-SiO2-based slags

The demanganization reaction kinetics of carbon-saturated liquid iron with an eight-component slag consisting of CaO-SiO₂-MgO-FeO-MnO-Al₂O₃-TiO₂-CaF₂ was investigated at 1553, 1623, and 1673 K in this study. The rate-controlling step (RCS) for the demanganization reaction with regard to the hot metal pretreatment conditions was studied via kinetics analysis based on the fundamental equation of heterogeneous reaction kinetics. From the temperature dependence of the mass transfer coefficient of a transition-metal oxide (MnO), the apparent activation energy of the demanganization reaction was estimated to be 189.46 kJ·mol-1 in the current study, which indicated that the mass transfer of MnO in the molten slag controlled the overall rate of the demanganization reaction. The calculated apparent activation energy was slightly lower than the values reported in the literature for mass transfer in a slag phase. This difference was attributed to an increase in the "specific reaction interface" (SRI) value, either as a result of turbulence at the reaction interface or a decrease of the absolute amount of slag phase during sampling, and to the addition of calcium fluoride to the slag.     

Two forms of the membrane-bound state of the first C2 domain (C2A) of synaptotagminⅠand calcium-triggered membrane insertion

Neurotransmitter release from presynaptic neurons into the synaptic cleft is an essential step in neurotrans-mission. The release is triggered by Ca2+ and completed by the fusion of neurotransmitters containing synaptic vesicles with the presynaptic membrane. Over the last decades, there has been a virtual explosion in identifica-tion of proteins that play critical roles in the release proc-ess. The leading candidates proposed as the Ca2+-sensors that regulate fusion are members of the synapt…