The genesis and environmental significance of red and black sedimentary interlayers in coral reef of well Nanyong 2

The results of paleogeomagnetics and geochemistry of the coral reef in well Nanyong 2 of Nansha Islands showed that the bottom of the black sedimentary interlayer corresponds to the conversion boundary line between Brunhes Postive Polarity and Matuyama Reversed Polarity (B/M) and the cold/warm (19/20) climatic conversion bounds on δ¹⁸O curve, 0.78 Ma ago; and the red sedimentary interlayer corresponds to the ReunionⅠpolarity excursion (reversion) of the geomagnetic field, 2.01—2.04 Ma ago. Comparing with the normal light-coloured coral reef rock, the magnetic susceptibility (c), residual magnetization intensity (Mr) and the content of MnO and Fe₂O₃ of the black sedimentary layer appeared obviously positive abnormity. The magnetic susceptibility (c), residual magnetization intensity (Mr) and the content of Fe₂O₃ of the red sedimentary layer also appeared positive abnormity. Combining with the analyzing results of paleontology, we hold that this pair of special and typical sedimentary interlayers was relative to the sudden change of paleoclimate, i.e. the global climatic change and its incidental polarity reversal of the geomagnetic field directly affected the living environment of the paleontological species as well as the dispersion and enrichment of some chemical elements, especially the elements sensitive to redox such as Fe and Mn. For example, the elements Fe and Mn concentrated in the glacial period would be largely oxidized and diluted when the climate warmed up suddenly, and the originally oxidized high valence Fe would be condensed again when the climate cooled suddenly. This is possibly one of the important reasons of appearing and disappearing of the red and black sedimentary events of coral reef in well Nanyong 2.     

Upper Jaramillo polarity transition and short geomagnetic event recorded in a loess section at Jingbian, northern China

Detailed rock-magnetic and paleomagnetic investigations have been carried out in a loess-paleosol sequence from the lower part of unit S9 to the bottom of L11 at Jingbian (37.4° N, 108.8°E), which demonstrates that the Upper Jaramillo polarity reversal and a short geomagnetic event bounded within the Jaramillo normal subchron have been revealed. The duration of this short event was about 8.5 ka. The statistical analysis showed that the virtual geomagnetic poles (VGP) paths of the short geomagnetic event are predominantly situated in the longitudinal sector over the America continent and its antipodal longitudes. While the VGP paths of the Upper Jaramillo recorded in the same loess-paleosol sequence exhibit a tight cluster located at western Australia.     

Geomagnetic polarity change, volcanic maxima and faunal extinction in the South Pacific

Studies of deep-sea sedimentary cores from Antarctic Pacific waters show that some volcanic maxima occurred when the geomagnetic polarity was changing. Upper mantle activity and geomagnetic polarity change may therefore be related. Coincidences of faunal extinction and geomagnetic polarity change may be explained by corresponding volcanically induced climatic changes.     

Dependence of the duration of geomagnetic polarity reversals on site latitude

An important constraint on the processes governing the geodynamo--the flow in the outer core responsible for generating Earth's magnetic field--is the duration of geomagnetic polarity reversals; that is, how long it takes for Earth's magnetic field to reverse. It is generally accepted that Earth's magnetic field strength drops to low levels during polarity reversals, and the field direction progresses through a 180 degrees change while the field is weak. The time it takes for this process to happen, however, remains uncertain, with estimates ranging from a few thousand up to 28,000 years. Here I present an analysis of the available sediment records of the four most recent polarity reversals. These records yield an average estimate of about 7,000 years for the time it takes for the directional change to occur. The variation about this mean duration is not random, but instead varies with site latitude, with shorter durations observed at low-latitude sites, and longer durations observed at mid- to high-latitude sites. Such variation of duration with site latitude is predicted by simple geometrical reversal models, in which non-dipole fields are allowed to persist while the axial dipole decays through zero and then builds in the opposite direction, and provides a constraint on numerical dynamo models.     

Remanence acquisition and its alteration on sediments

Previous palaeomagnetic work shows that the mechanism of remanence acquisition on sediments is very complicated. Different magnetizing processes under different conditions may produce some anomalous magnetic signals which have nothing to do with the changes of the geomagnetic field and are difficult to explain. The depositional remanent magnetization (DRM) may produce an inclination error and a bedding error, while postdepositional remanent magnetization (PDRM) may result in a time delay between the magnetic and sedimentary ages. When there are some different magnetic phases with different lock-in depths in the sediments, it is difficult to judge the depth of the reversal or excursion, or even the artificial magnetic signal may be produced. Even if there is only one magnetic phase in the sediment, the recorded magnetic signals may also be different if the lock-in depth is changed comparative to the lasting period of one reversal or excursion. Demagnetization may also change the primary magnetic records and the changes of water content may result in the displacement of magnetic boundary. The so-called “unstable core”, representing subtle changes in mineralogy into and out of a self-reversal region or a viscous magnetization region, gives a complicated palaeornagnetic record with many apparent changes in the palaeomagnetic direction. Moreover, some physical disturbances, such as biodisturbance, deformation, drilling processes and drying effects, may result in the remanence alteration. Some palaeomagnetic investigations demonstrate that good magnetic signals are invariably achieved on homogenous mud or clay sediments, but the worse signals on inhomogeneous profiles, especially on sandy layers.     

Latitude-dependence and dispersion of the westward drift in the geomagnetic field

The main geomagnetic field models of IGRF1900---2000 are used to study the latitude-dependence of the westward drift in the main field. The results show that the latitude-dependence exists in the magnetic components with different wavelengths (m=l-10). The globai-average westward drift rate of the component of m=l is 0.189°/a with the maximum of 0.295°/a at latitudes 40°-45°. The component of m=2 has an average drift rate of 0.411°/a with the maximum of 1.305°/a at latitude -60°. As for the components with further shorter wavelengths, the drift is generally restricted in a limited latitude range, and has many smaller drift rates. This latitude-dependence of westward drift can not be explained by rigid rotation of the earth's core. The results of this note also show that there is a negative dispersion in the westward drift, namely the components of long wavelengths drift faster than those of short wavelengths.This dispersion feature is not in agreement with Hide's MHD model. It is likely needed to find a new mechanism for explaining the observed feature of dispersion.     

A recording phase lag between ocean and continent climate changes: Constrained by the Matuyama/Brunhes polarity boundary

The Matuyama/Brunhes polarity boundary (MBPB) is recorded in Chinese loess L8, which is associated with the glacial period. It is proved that loess L8 is capable of recording earth’s secular variation, and the lock-in depth in Chinese loess is no more than that of marine sediments. Comparison with the location of MBPB in Chinese loess and marine sediments, it is put forward that there is a recording phase lag between ocean and continent climate changes.     

Trace element characteristics in the diopsides of peridotite xenoliths: a laser ablation-inductively coupled plasma-mass spectrometry study

Among the various xenoliths entrained by the Cenozoic Hannuoba basalts, peridotite is the most abundant one. The trace elements of the diopsides from the peridotite xenoliths were analysed by LA-ICP-MS. The overall depletion and some heterogeneity of the continental mantle beneath northern North China Craton were indicated by the characteristics of the trace elements. The ∑REE amount in diopside correlates with the Cr/(Cr+Al) ratio of diopside which is indicative of xenolith's partial melting degree. As the peridotite hosts and pyroxenite veins show similar REE distribution patterns, the composite xenoliths are probably formed by mantle deformation, rather than by the late metasomatism of mantle fluids/melts.     

Dramatic variations in the Earth’s main magnetic field during the 20th century

Analysis of the International Geomagnetic Reference Field (IGRF) 1900-2000 shows that the Earth's main magnetic field has changed dramatically during the 20th century: its dipole moment has decreased by 6.5% since 1900, the strengths of its quadrupole and octupole have increased by 95% and 74%, respectively, four major planetary-scale magnetic anomalies on the Earth's surface have enhanced by 21%-56%, and the magnetic center has shifted 200 km towards the Pacific Ocean. These time-variation features are similar to the behavior before a geomagnetic polarity reversal.     

The specific contribution of object’s origin on artifacts categorization

Gelman and Bloom found that adults and children＇s object naming was sensitive to how an object was created （man-made or not）, but they did not reveal on which specific level of conceptual system this effect was. Using a free-naming task and a force-choice task, two experiments were conducted to test a hypothesis that this effect was specifically on domain level （＂artifact/non-artifact＂ distinction）, in Experiment 1, participants were asked to name shortly-depicted objects, rate their confidence, and report their reasons for each naming response. Resuits showed that most of the naming responses in ＂man-made＂ condition were in artifact domain, and most in ＂natural＂ condition were in non-artifact domain, although in both conditions names were very divergent on basic level. In Experiment 2, another group of participants were asked to choose one from two names （one in artifact domain and the other in non-artifact domain） to match the same shortly-depicted objects presented in the first experiment. Results of Experiment 1 on domain level were replicated in Experiment 2. These convergent findings supported the hypothesis that the effect of object＇s origin is specifically on domain level of conceptual system of objects. Reasons explicitly reported for naming responses in Experiment 1 suggested that participants might automatically infer objects＇ functions in ＂man-made＂ condition but not in ＂natural＂ condition. Here the function-based hypothesis of artifacts classification is discussed.     

The Earth’s inner core deviation to plate movement

Under the premise of the Earth’s layer structure and mass distribution, the solid inner core cannot be stable in the center of the sphere. Thus, the deviation of the inner core is towards the sphere’s center and the liquid outer core must have asymmetrical thermal convection. Based on the two suggestions, a concise and self-consistent global motion model can be built. The model consists of the following cycle: an asymmetrical thermal convection structure in the outer core led by the dislocation of the inner core → the plume is in special upwell position because of differential activation → the formation and split of lithosphere → the split plates drift and assemble in a new location, the mass of which causes the inner core to deviate towards this direction again → the new asymmetry is formed. As this circulation continues, a definite and periodical motion emerges/forms. Its nonlinear features result in the Earth’s motion with simple mechanisms but complex behavior. Ultraterrestrial events may disturb or even interrupt this movement but would not significantly affect the cycle.     

Monitoring of the 2011 spring low ozone events in the Arctic region

Data from FY-3B SBUS and NOAA SBUV/2 were used to monitor ozone levels in the Arctic region from March 1 to April 5, 2011. Results revealed a significant ozone depletion in the area, with total ozone levels between 200–250 DU. The ozone levels recorded were 100–200 DU below normal, and in some parts the levels were as low as 200 DU, indicating a mini ozone-hole. During the sampling period, the ozone depletion area underwent identifiable expansion and detraction, a rotation around the North Pole from the west to the east, and a longitudinal movement from the Pole, spreading to the mid latitudes. The effects of these rare low ozone events were not only felt in the Arctic, but also extended to densely populated areas between Europe and the middle of Russia. In this region, rapidly increasing levels of ultraviolet radiation were detected at the Earth’s surface. Given the significant risk that this poses to both the environment and people’s health, this occurrence has significant global implications.     

Methane seeps, methane hydrate destabilization, and the late Neoproterozoic postglacial cap carbonates

Natural gas (methane) hydrates, the crystalline solids composed mainly of methane and water, are present in marine sediments of the continental margins and polar permafrost under a delicate balance of temperature (< 7℃) and hydrostatic pressure (> 50×10…     

Authenticated Diffie-Hellman key agreement protocol with forward secrecy

Forward secrecy is an important security property in key agreement protocol. Based on Ham＇s protocol, in this paper a new authenticated Diffie-Hellman key agreement protocol with half forward secrecy is proposed. This protocol is also based on a single cryptographic assumption, and is user authentication and shared key authentication. More importantly, our protocol provides forward secrecy with respect to one of the parties. For this reason, besides the advantages of Ham＇s protocol, in practice, our protocol can reduce the damages resulted from the disclosure of the user＇s secret key and it is very beneficial to today＇s communication with portable devices.     

Three-dimensional recon- struction and analysis of structure characteristics on senile plaques of Alzheimer’s disease

Alzheimer‘s disease is a progressive neurodegenerative disorder characterized by the presence of senile plaques primarily composed of amyloid β in brain. Abnor-mal secretion and aggregation of amyloid β are the key events in pathogenesis of Alzheimer‘s disease. Reduction of amyloid β production and inhibition of amyloid β aggregation to form senile plaques are hopeful strategies for the treatment and prevention of Alzheimer‘s disease. In the present study, the silver and immunohistochemical staining methods were applied to discover senile plaques in the hippocampus of Alzheimer‘s disease patients, and then images were processed and three-dimensionally reconstructed by Matlab and AVS software. The structure characteristics of senile plaques were measured through correlation function calculation and fractal dimension by a computer-aided method. Diffuse plaque had no amyloid center, but classic plaque presented compact central core structure; two types of plaques were both of porous structure, but the sizes of their pores were significantly different. Furthermore, there was difference in fractal dimension value between the diffuse plaque and classic plaque in the two staining methods. The comparison of structure characteristics between two types of plaques indicated that they developed independently. Establishment of the methods for reconstructing the three-dimensional structure of senile plaque and analyzing their structure characteristics is helpful for further study on the aggregation mechanism of senile plaque.     

GIS-based highway geological hazard information management and decision support system

Based on the practical application of Geology Information System(GIS) throughout the world, combined with the characters of road’s geological hazard and it’s supervision, the paper introduces on the importance of the research on road’s geological hazards information management and decision-making support system. The paper also analyzes the system’s target, the principles and key techniques in developing the system. In the research, we developed the GIS-based road’s geological hazard information management and decision-making support system and applied it to one speedway in the west of China where contains typical geological hazards. The system based on the database of road’s geological hazard on the grounds of spatial graphic information and attribute information. By virtue of the scientific assessment and prediction mathematical model, integrating the GIS’s strongpoint on spatial analyzing, the system is capable of visualizing the regionalization of road according to the geological hazards it contains, and accurately assessing and predicting geological hazards, thus efficiently assists the road construction and management units in the decision making on controlling the geological hazards and reducing the related loss. Biography: WANG Weidong (1971–), male, Associate professor, Ph.D. candidate, research direction: road and railway engineering, management science and engineering.     

闪电电场波形脉冲序列极性变化及成因

地基闪电探测站记录的闪电电场信号普遍存在极性反转现象,不同测站的极性反转时刻不同,目前对该现象没有较清晰的认识。本文详细阐述了闪电放电引起的电场变化信号的测量原理,在此基础上,利用宽带电场和甚高频辐射数据,结合闪电甚高频辐射源的定位结果,分析了闪电电场脉冲极性反转现象的特征和原因。对比基站间距为5 km量级的多站数据,发现不同测站数据电场极性反转并不同时发生,并且极性反转常伴随着脉冲幅值的降低,因此常常导致定位时脉冲提取缺失或到达时间提取的误差增大。利用宽带电场定位和甚高频辐射源定位相互补充,在获得闪电精细化三维定位基础上分析发现,闪电主通道头部的发展方向改变,是导致地面探测站的垂直电场出现极性反转现象的可能原因,主通道头部携带的大量电荷靠近或远离是地面垂直电场变化测量装置脉冲波动的主要原因。对于不同方位的探测站,闪电主通道头部相对运动是导致不同探测站出现脉冲极性反转时刻不同的主要原因。针对极性反转现象造成定位效率下降问题,本文提出了希尔伯特能量谱的解决方案,定位出的闪电辐射源数量提高约9%。     

Prediction of β -turns using double BP network with novel coding schemes of amino acids

Protein structure prediction is one of the most important problems in structural biology. β-turns are always at the turn of a protein tertiary structure and thus β-turn’s prediction is a key step in tertiary structure prediction. There are some methods to predict β-turns based on machine learning techniques such as k-nearest method, neural networks and support vector machine. In this paper, we construct a classifier using double BP networks and put forward two novel methods to code amino acids in the second network. When trained and tested on different datasets, they achieve more accuracy than other coding methods.      

Asphaltenes in oil reservior recovery

Asphaltene is one of the important compositions in oil reservoirs, while it is also a major factor that causes difficulties in oil recovery and oil post-processings. Up to date, study on asphaltenes in oil recovery is still a bottleneck problem. In this paper, the advances of studies on asphaltenes are reviewed, and some directions for further studying are suggested. What is reviewed in the paper includes the precipitation studies of asphaltenes, the degradation studies of asphaltenes and the applications of asphaltene’s studying in oil recovery; furthermore, it is regarded as a promising direction to study the possible applications of asphaltene’s selectively decomposing by chemical reagents in oil recovery.     

Speeding up implementation for Shor’s factorization quantum algorithm

In this paper, based on the implementation of semiclassical quantum Fourier transform, we first propose the concept of generation vector of ternary binary representation, construct the generation function’s truth table, prove that the generation vector of ternary binary representation is one kind of k ’s NAF representation and further find that its number of nonzero is not more than [(⌈log k⌉ + 1)/2]. Then we redesign a quantum circuit for Shor’s algorithm, whose computation resource is approximately equal to that of Parker (Their requirements of elementary quantum gate are both O(⌈logN⌉³), and our circuit requires 2 qubits more than Parker’s). However, our circuit is twice as fast as Parker’s.