Dynamics of excited m-dichlorobenzene

Dynamics of excited m-dichlorobenzene is investigated in real time by femtosecond pump-probe method, combined with time-of-flight mass spectrometric detection in a supersonic molecular beam. The yields of the parent ion and daughter ion C6H4CI+ are examined as a function of the delay between the 270 and 810 nm femtosecond laser pulses, respectively. The lifetime of the first singlet excited state S-1 of m-dichlorobenzene is measured. The origin of this daughter ion C6H4CI+ is discussed. The ladder mechanism is proposed to form the fragment ion. In addition, our experimental results exhibit a rapid damped sinusoidal oscillation over intermediate time delays, which is due to quantum beat effects.

全球气候变暖争议中的核心问题

综合分析了全球气候变暖争议中的3个核心问题:①全球变暖停滞了吗?回答是不一定。虽然根据HadCRUT3序列显示1999—2008年温度增量很小,但是这10年仍是过去30年中最暖的10年。而根据NASAGISS序列,则同期温度增量仍达到0.19℃/10a。目前全球地表气温在一个较暖平台上振荡,不能忽视自然气候变率。②气候变暖完全是由人类活动造成的吗?回答是否定的。虽然温室效应加剧可能是全球变暖的主要原因。但是,ENSO、太阳活动、火山活动、热盐环流等对全球变暖也有影响,在年代际及年际尺度上其影响甚至有时可能

Potential Landscape and Flux Framework of Nonequilibrium Networks: Robustness, Dissipation, and Coherence of Biochemical Oscillations

We established a theoretical framework for studying nonequilibrium networks with two distinct natures essential for characterizing the global probabilistic dynamics: the underlying potential landscape and the corresponding curl flux. We applied the idea to a biochemical oscillation network and found that the underlying potential landscape for the oscillation limit cycle has a distinct closed ring valley (Mexican hat-like) shape when the fluctuations are small. This global landscape structure leads to attractions of the system to the ring valley.

Robustness and Coherence of a Three-Protein Circadian Oscillator: Landscape and Flux Perspectives

Three-protein circadian oscillations in cyanobacteria sustain for weeks. To understand how cellular oscillations function robustly in stochastic fluctuating environments, we used a stochastic model to uncover two natures of circadian oscillation: the potential landscape related to steady-state probability distribution of protein concentrations; and the corresponding flux related to speed of concentration changes which drive the oscillations. The barrier height of escaping from the oscillation attractor on the landscape provides a quantitative measure of the robustness and coherence for oscillations against intrinsic and external fluctuations. The difference between the locations of the zero total driving force and the extremal of the potential provides a possible experimental probe and quantification of the force from curl flux. These results, correlated with experiments, can help in the design of robust oscillatory networks.

Single molecule dynamics and statistical fluctuations of gene regulatory networks: A repressilator

The authors developed a time dependent method to study the single molecule dynamics of a simple gene regulatory network: a repressilator with three genes mutually repressing each other. They quantitatively characterize the time evolution dynamics of the repressilator. Furthermore, they study purely dynamical issues such as statistical fluctuations and noise evolution. They illustrated some important features of the biological network such as monostability, spirals, and limit cycle oscillation. Explicit time dependent Fano factors which describe noise evolution and show statistical fluctuations out of equilibrium can be significant and far from the Poisson distribution. They explore the phase space and the interrelationships among fluctuations, order, amplitude, and period of oscillations of the repressilators. The authors found that repressilators follow ordered limit cycle orbits and are more likely to appear in the lower fluctuating regions. The amplitude of the repressilators increases as the suppressing of the genes decreases and production of proteins increases. The oscillation period of the repressilators decreases as the suppressing of the genes decreases and production of proteins increases.

Study on sensing properties of tin oxide CO gas sensor with low power consumption

In this paper, the fabrication method of a new type of carbon monoxide gas sensor based on SnOx with low power consumption and its sensing characteristics have been reported. The electric conductance of this type of sensor evolves oscillation form regularly when the sensor is exposed to low level of CO gas. The oscillation amplitude is directly proportional to the concentration of CO gas over a wide range. The effects of relevant factors. such as. humidity, temperature and interference gases on the sensor properties were examined. The sensing oscillation response mechanism was also discussed.

Mixed ion transfer analysis in redox processes of electroactive thin films

Electrochemical quartz crystal microbalance (EQCM) technique was used to measure the ion transfer in redox processes in electroactive organic thin films, such as self-assembled monolayer (SAM) (4-pyridyl hydroquinone, abbr. 4PHQ), multilayer based on SAM and conducting polymer film (here poly-(3,4-ethylenedioxythiophene), abbr. PEDOT). A mechanism of mixed ion transfer is developed and presented. Analysis of mixed ion transfer during redox processes successfully elucidates the deviation of oscillation frequency of the quartz crystal from theoretical expectation.

Millennial-scale paleoceanography in Okinawa Trough during Late Quaternary period

Based on the analyses of foraminifer and accelerator mass spectrometer radiocarbon dating in DGKS9603 core from mid-Okinawa Trough close to bottom, oscillation curve, which expressed the relation between the surface water temperature and the depth, has been obtained by using foraminifer analysis and calculation of FP-12E transfer function. The whole core indicated seven cold phases and eight warm phases. Obvious expression of low temperature event during Middle and Late Holocene, YD,H1,H2,H3 and H4 events, as well as the short cold phase during the middle last glacial period, implied that short shifts since 50 kaBP would have been global significance. Sedimentation rate during cold phases is usually faster than that in warm stages, with the lowest rate in Holocene, which may be connected with rising sea level and principal axial of Kuroshio Current moving to west. Volcanic activities highly developed in Okinawa Trough during the Quaternary period, thus abundant volcanic glass and pumice were well preserved.

Evolution and variability of the East Asian summer monsoon during the Pliocene: Evidence from clay mineral records of the South China Sea

The Late Pliocene is thought to be characterized by the simultaneous intensification of both the East Asian winter monsoon (EAWM) and East Asian summer monsoon (EASM). However, the evolution of the EASM during the Pliocene remains still controversial and only little is known about the dynamics of the EASM during the Pliocene on orbital time scales. Here we use clay mineral assemblages in sediments from Ocean Drilling Program (ODP) Site 1143 in the southern South China Sea (SCS) to obtain proxy records of past changes in the EASM climate during the Pliocene. Provenance analysis suggests that illite, chlorite and kaolinite originated mainly from the Mekong River drainage area. Smectite was derived mainly from the Indonesian islands. The kaolinite/illite ratio and the chemical index of alteration (CIA) of siliciclastic sediments allowed us to reconstruct the history of chemical weathering and physical erosion of the Mekong River drainage area and thus, the evolution of,the EASM during the Pliocene. Our clay minerals proxy data suggests a stronger EASM during the Early Pliocene than during the Late Pliocene. We propose that the long-term evolution of the EASM has been driven by global cooling rather than the uplift of the Tibetan Plateau. Spectral analysis of kaolinite/ illite ratio displays a set of strong periodicities at 100 ka, 30 ka, 28 ka, 25 ka, and 22 ka. with no clear obliquityrelated signal. Our study suggests that the Pliocene EASM intensity on orbital time scales is not only controlled by the Northern Hemisphere summer insolation, but also strongly influenced by equatorial Pacific ENSO-like ocean atmosphere dynamics. (C) 2010 Elsevier B.V. All rights reserved.

The variation of upper ocean structure and paleoproductivity in the Kuroshio source region during the last 200 kyr

A core from the source region of the Kuroshio warm current (east of the Luzon Island) was analyzed using several proxies in order to study the variability of the Western Pacific Warm Pool (WPWP) during the last two glacial-interglacial cycles. Primary productivity (PP) variations were deduced from variations in the coccolith flora. Primary productivity was higher during glacial periods (the end of Marine Isotope Stage [MIS] 3, some periods in MIS 2 and 6), and decreased during interglacial periods (MIS 7, MIS Se and probably MIS 5c-5d), with the lowest PP in MIS 5e. variations in the delta C-13 difference in benthic and bulk carbonate, thus in the vertical gradient of delta C-13 in dissolved inorganic carbon (Delta delta C-13(c). (wuellerstorfi-N. dutertrei) and Delta delta C-13(c.) (wuellerstorfi-coccolith)) Coincided With the PP Changes, showing that export productivity was low during interglacial periods (MIS 7, MIS 5e and Holocene) and high during glacial periods (MIS 6, probably MIS 5c-5d, late MIS 4 and late MIS 3). Comparison of foraminiferal carbonate dissolution indicators and PP changes reveals that nannofossil assemblage in core Ph05-5 is not sensitive to carbonate dissolution intensity. The depth of the thermocline (DOT) was estimated from planktonic forminiferal assemblages, and was relatively greater during interglacial periods (MIS 7, MIS 5e, probably MIS 5c and Holocene) than during glacials (middle MIS 6, probably MIS 5b and 5d, some periods in MIS 4, MIS 3 and MIS 2). Good coherence between the paleoproductivity records and the DOT suggests that the DOT changes could be the primary control factor in changes of paleoproductivity, and the glacial high productivity in the Kuroshio source region could be associated with a global increase of nutrient concentration in the intermediate waters that upwelled into the photic zone. The low CO2 values derived for intervals of high productivity and a relatively shallow DOT suggest that the changes in biological productivity and DOT in the equatorial Pacific could have modified atmospheric CO2 concentrations. High Sea Surface Temperatures (SSTs) during the warm MIS 5e in combination with intensified monsoonal rain fall could have resulted in a more intense stratification of the upper waters, resulting in low nutrient supply to the surface waters and a resulting decrease in productivity. (C) 2010 Elsevier B.V. All rights reserved.

25ka B.P.以来黑潮流域古环境演化对高频全球变化事件的响应

本文利用黑潮流域主流轴上的两个柱状沉积物岩芯MD05-2908以及PC-1为研究材料，在AMS14C测年的基础上，利用高分辨率的有机地球化学分析记录结合浮游有孔虫氧、碳同位素，恢复并重建了过去25,000 cal a BP以来黑潮流域古海洋环境演化的历史。以及表层海水生产力以及物质输送状况的演化历史。通过利用Uk’37古海水温度以及盐度指标恢复重建了过去25,000 cal a BP以来海洋表层海水温度、盐度；通过机碳、氮含量以及同位素变化、长链正构烷烃以及正构烷醇等指标重建了过去7000a B.P.以来的陆源物质输入历史；通过长链不饱和烯酮含量以及有机碳同位素指标恢复了过去7000a B.P.以来海水表层生产力的历史。此外，通过基于以上各种指标的环境信息与区域以及全球其它气候记录进行对比研究以及不同环境指标的时间系列分析，探讨了该区表层环流系统以及生产力的演化对于全球气候变化的响应，揭示了不同尺度的短周期高频率全球变化事件在黑潮流域的具体作用过程和响应机制。通过这些研究取得了以下的主要认识： 基于有机地球化学指标的古气候环境记录与黑潮流域已有的研究成果有很好的对应关系，从我们高分辨率的有机地球化学记录中可以识别出全新世黑潮强弱变化的几次明显的事件；25000a B.P.以来黑潮流域的环境变化与全球环境变化有着很好的对应性，黑潮强弱演化总体趋势与全球气候背景演化相一致，黑潮对高频气候变化事件的记录与全球记录具有同步性，这种同步性尤其体现在末次冰消期以来的气候快速高频振荡以及全新世以来的气候突变事件上。 全球性的高频气候事件对黑潮主体本身及黑潮流域的相邻区域的大气和海洋环流都具有重要的控制作用，这种控制作用主要通过副高、ITCZ以及季风三种气候要素之间相互关联、彼此影响造成的。具体表现为：太阳辐射量的减少导致热力差异减小，这种相对减小弱化了热带西太平洋的对流活动，造成了西太平洋副热带高压长期偏南、偏东，ITCZ平均北界位置偏南，降雨带长时间集中在南部地区，增强的降雨量提高了风化剥蚀以及沉积物向海洋搬运的能力，陆源物质供应量增加；同时，辐射量以及热力差的减小又与加强的东亚冬季风相联系，增强的冬季风导致了近底层“雾状层”物质的向海传输，物质传输效率增高。这种物源供应以及搬运量的双重增加导致了冲绳海槽流域物质通量的增加。 基于有机地球化学指标的海洋表层生产力的变化与陆源物质供应量以及黑潮流的强弱变化存在着对应关系，通常情况增加的海洋表层生产力对应着高的陆源物质输入以及相对较弱的黑潮。这种变化与东亚夏季风的以及冬季风的强弱都有很好的一致性。陆源物质的输入增加了表层营养物质的含量，导致生产力的勃发；陆源物质的输入增加又对应着减少的太阳辐射量，偏南的ITCZ北界位置以及副热带高压，这些对应于减弱的东亚夏季风（增强的东亚冬季风）。 黑潮流域的高沉积速率事件对应于减弱的黑潮强度和增加的ENSO频度，这些事件与上述的副热带高压、ITCZ位移和强弱的变化相一致。黑潮流域过去25000a B.P.以来南北温度的差异有冰期加大而全新世减小的趋势，但这种冰期与全新世的差异很小，我们认为末次盛冰期的时候黑潮主流轴没有移出冲绳黑潮，只是由于强度的减弱受陆架水体的影响有所加大。 黑潮流域很好的记录到了包括数千年尺度的D/O旋回周期到大气——海洋系统内部振荡所致的PDO、NAO等数十年尺度的高频振荡，说明黑潮流域对过去全球及区域环境变化事件有很好的响应。黑潮流域各古海洋指标所记录周期上的一致性说明这些环境因子控制机理上具有的一致性，即大背景上受太阳活动所引起的辐射量变化控制，局部的高频快速气候波动又受到局域性的气候因素如海气相互作用的放大影响。

Two modes of dipole events in tropical Indian Ocean

By analyzing the distributions of subsurface temperature and the surface wind stress anomalies in the tropical Pacific and Indian Oceans during the Indian Ocean Dipole (IOD) events, two major modes of the IOD and their formation mechanisms are revealed. (1) The subsurface temperature anomaly (STA) in the tropical Indian Ocean during the IOD events can be described as a "<" -shaped and west-east-oriented dipole pattern; in the east side of the "<" pattern, a notable tongue-like STA extends westward along the equator in the tropical eastern Indian Ocean; while in the west side of the "<" pattern, the STA has opposite sign with two centers (the southern one is stronger than the northern one in intensity) being of rough symmetry about the equator in the tropical mid-western Indian Ocean. (2) The IOD events are composed of two modes, which have similar spatial pattern but different temporal variabilities due to the large scale air-sea interactions within two independent systems. The first mode of the IOD event originates from the air-sea interaction on a scale of the tropical Pacific-Indian Ocean and coexists with ENSO. The second mode originates from the air-sea interaction on a scale of the tropical Indian Ocean and is closely associated with changes in the position and intensity of the Mascarene high pressure. The strong IOD event occurs when the two modes are in phase, and the IOD event weakens or disappears when the two modes are out of phase. Besides, the IOD events are normally strong when either of the two modes is strong. (3) The IOD event is caused by the abnormal wind stress forcing over the tropical Indian Ocean, which results in vertical transports, leading to the upwelling and pileup of seawater. This is the main dynamic processes resulting in the STA. When the anomalous easterly exists over the equatorial Indian Ocean, the cold waters upwell in the tropical eastern Indian Ocean while the warm waters pileup in the tropical western Indian Ocean, hence the thermocline in the tropical Indian Ocean is shallowed in the east and deepened in the west. The off-equator component due to the Coriolis force in the equatorial area causes the upwelling of cold waters and the shallowing of the equatorial India Ocean thermocline. On the other hand, the anomalous anticyclonic circulations and their curl fields located on both sides of the equator, cause the pileup of warm waters in the central area of their curl fields and the deepening of the equatorial Indian Ocean thermocline off the equator. The above three factors lead to the occurrence of positive phase IOD events. When anomalous westerly dominates over the tropical Indian Ocean, the dynamic processes are reversed, and the negative-phase IOD event occurs.

Subtropical dipole mode in the Southern Hemisphere: A global view

A global wavenumber-3 dipole SST mode is showed to exist in the Southern Hemisphere subtropical climate variability in austral summer. A positive (negative) phase of the mode is characterized by cool (warm) SST anomalies in the east and warm (cool) SST anomalies in the southwest of the south Indian, Pacific, and Atlantic Oceans, respectively. This coherent dipole structure is largely a response of ocean mixed layer to the atmospheric forcing characterized by migration and modulation of the subtropical high-pressures, in which the latent heat flux play a leading role through wind-induced evaporation, although ocean dynamics may also be crucial in forming SST anomalies attached to the continents. Exploratory analyses suggest that this mode is strongly damped by the negative heat flux feedback, with a persistence time about three months and no spectral peak at interannual to decadal time scales. As the subtropical dipole mode is linearly independent of ENSO and SAM, whether it represents an additional source of climate predictability should be further studied. Citation: Wang, F. (2010), Subtropical dipole mode in the Southern Hemisphere: A global view, Geophys. Res. Lett., 37, L10702, doi: 10.1029/2010GL042750.

Progress of large-scale air-sea interaction studies in China

This paper summarizes the progress of large-scale air-sea interaction studies that has been achieved in China in the four-year period from July 1998 to July 2002, including seven aspects in the area of the air-sea interaction, namely air-sea interaction related to the tropical Pacific Ocean, monsoon-related air-sea interaction, air-sea interaction in the north Pacific Ocean, air-sea interaction in the Indian Ocean, air-sea interactions in the global oceans, field experiments, and oceanic cruise surveys. However more attention has been paid to the first and the second aspects because a large number of papers in the reference literature for preparing and organizing this paper are concentrated in the tropical Pacific Ocean, such as the ENSO process with its climatic effects and dynamics, and the monsoon-related air-sea interaction. The literature also involves various phenomena with their different time and spatial scales such as intraseasonal, annual, interannual, and interdecadal variabilities in the atmosphere/ocean interaction system, reflecting the contemporary themes in the four-year period at the beginning of an era from the post-TOGA to CLIVAR studies. Apparently, it is a difficult task to summarize the great progress in this area, as it is extracted from a large quantity of literature, although the authors tried very hard.