996 resultados para Hydrologic cycle.


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The annual cycle of nutrient-phytoplankton dynamics in Bohai Sea (BS) is simulated using a coupled physical-biological model in this study. By comparison, the modeled seasonal variations of nutrients and primary productivity agree with observations rather well. Although the annual cycles of chlorophyll a and primary production are both characterized by a double-peak configuration, a structural difference is still apparent: the phytoplankton biomass reaches the highest value in spring while summer is characterized by the most productivity in the BS, which can be ascribed to the combined impact of seawater temperature and zooplankton-grazing pressure on the growth of algae. Based on the validated simulations, the annual budgets of carbon, nitrogen and phosphorus are estimated, and are about 0.82 mt C surplus, 39 kt N deficit and 12kt P surplus, respectively, implying that the BS ecosystem is somewhat nitrogen limited. The contribution of two external nutrient sources, namely river discharges and resuspended sediments, to the growth of algae is also examined numerically, and it is found that the influence of river-borne nutrients mainly concentrates in estuaries, whereas the reduction of sediment-borne nutrients may significantly inhibit the onset of algae bloom in the whole BS. (c) 2007 Elsevier Ltd. All rights reserved.

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In general, competition between buoyancy mechanisms and mixing dynamics largely determines the water column structure in a shelf sea. A three dimensional baroclinic ocean model forced by surface heat fluxes and the 2.5 order Mellor-Yamada turbulence scheme is used to simulate the annual cycle of the temperature in the Bohai Sea. The difference between the sea surface temperature (SST) and sea bottom temperature (SBT) is used to examine the evolution of its vertical stratification. It is found that the water column is well-mixed from October to March and that the seasonal thermocline appears in April, peaks in July and then weakens afterwards, closely following the heat budget. In addition, the Loder parameter based on the topography and tidal current amplitude is also computed in order to examine tidal fronts in the BS, which are evident in summer months when the wind stirring mechanism is weak.

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The main modes of interannal variabilities of thermocline and sea surface wind stress in the tropical Pacific and their interactions are investigated, which show the following results. (1) The thermocline anomalies in the tropical Pacific have a zonal dipole pattern with 160 W as its axis and a meridional seesaw pattern with 6-8 degrees N as its transverse axis. The meridional oscillation has a phase lag of about 90 to the zonal oscillation, both oscillations get together to form the El Nino/La Nina cycle, which behaves as a mixed layer water oscillates anticlockwise within the tropical Pacific basin between equator and 12 degrees N. (2) There are two main patterns of wind stress anomalies in the tropical Pacific, of which the first component caused by trade wind anomaly is characterized by the zonal wind stress anomalies and its corresponding divergences field in the equatorial Pacific, and the abnormal cross- equatorial flow wind stress and its corresponding divergence field, which has a sign opposite to that of the equatorial region, in the off-equator of the tropical North Pacific, and the second component represents the wind stress anomalies and corresponding divergences caused by the ITCZ anomaly. (3) The trade winds anomaly plays a decisive role in the strength and phase transition of the ENSO cycle, which results in the sea level tilting, provides an initial potential energy to the mixed layer water oscillation, and causes the opposite thermocline displacement between the west side and east side of the equator and also between the equator and 12 degrees N of the North Pacific basin, therefore determines the amplitude and route for ENSO cycle. The ITCZ anomaly has some effects on the phase transition. (4) The thermal anomaly of the tropical western Pacific causes the wind stress anomaly and extends eastward along the equator accompanied with the mixed layer water oscillation in the equatorial Pacific, which causes the trade winds anomaly and produces the anomalous wind stress and the corresponding divergence in favor to conduce the oscillation, which in turn intensifies the oscillation. The coupled system of ocean-atmosphere interactions and the inertia gravity of the mixed layer water oscillation provide together a phase-switching mechanism and interannual memory for the ENSO cycle. In conclusion, the ENSO cycle essentially is an inertial oscillation of the mixed layer water induced by both the trade winds anomaly and the coupled ocean-atmosphere interaction in the tropical Pacific basin between the equator and 12 degrees N. When the force produced by the coupled ocean-atmosphere interaction is larger than or equal to the resistance caused by the mixed layer water oscillation, the oscillation will be stronger or maintain as it is, while when the force is less than the resistance, the oscillation will be weaker, even break.

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温度跃层是反映海洋温度场的重要物理特性指标,对水下通讯、潜艇活动及渔业养殖、捕捞等有重要影响。本文利用中国科学院海洋研究所“中国海洋科学数据库”在中国近海及西北太平洋(110ºE-140ºE,10ºN-40ºN)的多年历史资料(1930-2002年,510143站次),基于一种改进的温跃层判定方法,分析了该海域温跃层特征量的时空分布状况。同时利用Princeton Ocean Model(POM),对中国近海,特别是东南沿海的水文结构进行了模拟,研究了海洋水文环境对逆温跃层的影响。最后根据历史海温观测资料,利用EOF分解统计技术,提出了一种适于我国近海及毗邻海域,基于现场有限层实测海温数据,快速重构海洋水温垂直结构的统计预报方法,以达到对现场温跃层的快速估计。 历史资料分析结果表明,受太阳辐射和风应力的影响,20°N以北研究海域,温跃层季节变化明显,夏季温跃层最浅、最强,冬季相反,温跃层厚度的相位明显滞后于其他变量,其在春季最薄、秋季最厚。12月份到翌年3月份,渤、黄及东海西岸,呈无跃层结构,西北太平洋部分海域从1月到3月份,也基本无跃层结构。在黄海西和东岸以及台湾海峡附近的浅滩海域,由于风力搅拌和潮混合作用,温跃层出现概率常年较低。夏季,海水层化现象在近海陆架海域得到了加强,陆架海域温跃层强度季节性变化幅度(0.31°C/m)明显大于深水区(约0.05°C/m),而前者温跃层深度和厚度的季节性变化幅度小于后者。20°N以南研究海域,温跃层季节变化不明显。逆温跃层主要出现在冬、春季节(10月-翌年5月)。受长江冲淡水和台湾暖流的影响,东南沿海区域逆温跃层持续时间最长,出现概率最大,而在山东半岛北及东沿岸、朝鲜半岛西及北岸,逆温跃层消长过程似乎和黄海暖流有关。多温跃层结构常年出现于北赤道流及对马暖流区。在黑潮入侵黄、东、南海的区域,多温跃层呈现明显不同的季节变化。在黄海中部,春季多温跃层发生概率高于夏季和秋季,在东海西部,多跃层主要出现在夏季,在南海北部,冬季和春季多温跃层发生概率大于夏季和秋季。这些变化可能主要受海表面温度变化和风力驱动的表层流的影响。 利用Princeton Ocean Model(POM),对中国东南沿海逆温跃层结构进行了模拟,模拟结果显示,长江冲淡水的季节性变化以及夏季转向与实际结果符合较好,基本再现了渤、黄、东海海域主要的环流、温盐场以及逆温跃层的分布特征和季节变化。通过数值实验发现,若无长江、黄河淡水输入,则在整个研究海域基本无逆温跃层出现,因此陆源淡水可能是河口附近逆温跃层出现的基本因素之一。长江以及暖流(黑潮和台湾暖流)流量的增加,均可在不同程度上使逆温跃层出现概率及强度、深度和厚度增加,且暖流的影响更加明显。长江对东南沿海逆温跃层的出现,特别是秋季到冬季初期,有明显的影响,使长江口海域逆温跃层位置偏向东南。暖流对于中国东南沿海的逆温跃层结构,特别是初春时期,有较大影响,使长江口海域的逆温跃层位置向东北偏移。 通过对温跃层长期变化分析得出,黄海冷水团区域,夏季温跃层强度存在3.8年左右的年际变化及18.9年左右的年代际变化,此变化可能主要表现为对当年夏季和前冬东亚地区大气气温的热力响应。东海冷涡区域,夏季温跃层强度存在3.7年的年际变化,在El Nino年为正的强度异常,其可能主要受局地气旋式大气环流变异所影响。谱分析同时表明,该海域夏季温跃层强度还存在33.2年的年代际变化,上世纪70年代中期,温跃层强度由弱转强,而此变化可能与黑潮流量的年代际变化有关。 海洋水温垂直结构的统计预报结果显示,EOF分解的前四个主分量即能够解释原空间点温度距平总方差的95%以上,以海洋表层附近观测资料求解的特征系数推断温度垂直结构分布的结果最稳定。利用东海陆架区、南海深水区和台湾周边海域三个不同区域的实测CTD样本廓线资料,对重构模型的检验结果表明,重构与实测廓线的相关程度超过95%的置信水平。三个区重构与实测温度廓线值的平均误差分别为0.69℃,0.52℃,1.18℃,平均重构廓线误差小于平均气候偏差,统计模式可以很好的估算温度廓线垂直结构。东海陆架海区温度垂直重构廓线与CTD观测廓线获得的温跃层结果对比表明,重构温跃层上界、下界深度和强度的平均绝对误差分别为1.51m、1.36m和0.17℃/m,它们的平均相对误差分别为24.7%、8.9%和22.6%,虽然温跃层深度和强度的平均相对误差较大,但其绝对误差量值较小。而在南海海区,模型重构温跃层上界、下界和强度的平均绝对预报误差分别为4.1m、27.7m和0.007℃/m,它们的平均相对误差分别为16.1%、16.8%和9.5%,重构温跃层各特征值的平均相对误差都在20%以内。虽然南海区温跃层下界深度平均绝对预报误差较大,但相对于温跃层下界深度的空间尺度变化而言(平均温跃层下界深度为168m),平均相对误差仅为16.8%。因此说模型重构的温度廓线可以达到对我国陆架海域、深水区温跃层的较好估算。 基于对历史水文温度廓线观测资料的分析及自主温跃层统计预报模型,研制了实时可利用微机简单、快捷地进行温跃层估算及查询的可视化系统,这是迄今进行大范围海域温跃层统计与实时预报研究的较系统成果。

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The seasonal evolution of dissolved inorganic carbon (DIC) and CO2 air-sea fluxes in the Jiaozhou Bay was investigated by means of a data set from four cruises covering a seasonal cycle during 2003 and 2004. The results revealed that DIC had no obvious seasonal variation, with an average concentration of 2035 mu mol kg(-1) C in surface water. However, the sea surface partial pressure of CO2 changed with the season. pCO(2) was 695 mu atm in July and 317 mu atm in February. Using the gas exchange coefficient calculated with Wanninkhof's model, it was concluded that the Jiaozhou Bay was a source of atmospheric CO, in spring, summer, and autumn, whereas it was a sink in winter. The Jiaozhou Bay released 2.60 x 10(11) mmol C to the atmosphere in spring, 6.18 x 10(11) mmol C in summer, and 3.01 x 10(11) mmol C in autumn, whereas it absorbed 5.32 x 10(10) mmol C from the atmosphere in winter. A total of 1.13 x 10(11) mmol C was released to the atmosphere over one year. The behaviour as a carbon source/sink obviously varied in the different regions of the Jiaozhou Bay. In February, the inner bay was a carbon sink, while the bay mouth and the Outer bay were carbon sources. In June and July, the inner and Outer bay were carbon sources, but the strength was different, increasing from the inner to the outer bay. In November, the inner bay was a carbon source, but the bay Mouth was a carbon sink. The outer bay was a weaker CO2 Source. These changes are controlled by many factors, the most important being temperature and phytoplankton. Water temperature in particular was the main factor controlling the carbon dioxide system and the behaviour of the Jiaozhou Bay as a carbon source/sink. The Jiaozhou Bay is a carbon dioxide source when the water temperature is higher than 6.6 degrees C. Otherwise, it is a carbon sink. Phytoplankton is another controlling factor that may play an important role in behaviour as a carbon source or sink in regions where the source or sink nature is weaker.

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Rhein, an anthraquinone derivative of rhubarb, inhibits the proliferation of various human cancer cells. In this paper, we focused on studying the effects of rhein on human hepatocelluar carcinoma BEL-7402 cells and further understanding the underlying molecular mechanism in an effort to make the potential development of rhein in the treatment of cancers. Using MTT assay and flow cytometry, we demonstrate a critical role of rhein in the suppression of BEL-7402 cell proliferation in a concentration- and time-dependent manner. The increase of apoptosis rate was observed after incubation of BEL-7402 cells with rhein at 50-200 mu M for 48 hours, and the cells exhibit typical apoptotic features including cellular morphological change and chromatin condensation. Moreover, rhein-induced cell cycle S-phase arrest. Additionally, after rhein treatment, expression levels of c-Myc gene were decreased, while those of caspase-3 gene were increased in a dose-dependent manner by using real-time PCR assay. The results demonstrate for the first time that cell cycle S-phase arrest is one of the mechanisms of rhein in inhibition of BEL-7402 cells. Rhein plays its role by inducing cell cycle arrest via downregulation of oncogene c-Myc and apoptosis through the caspase-dependent pathway. It is expected that rhein will be effective and useful as a new agent in hepatocelluar carcinoma treatment in the future.

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Urquhart, C., Spink, S., Thomas, R., Yeoman, A., Durbin, J., Turner, J., Fenton, R. & Armstrong, C. (2004). JUSTEIS: JISC Usage Surveys: Trends in Electronic Information Services Final report 2003/2004 Cycle Five. Aberystwyth: Department of Information Studies, University of Wales Aberystwyth. Sponsorship: JISC

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Urquhart, C. (editor for JUSTEIS team), Spink, S., Thomas, R., Yeoman, A., Durbin, J., Turner, J., Armstrong, A., Lonsdale, R. & Fenton, R. (2003). JUSTEIS (JISC Usage Surveys: Trends in Electronic Information Services) Strand A: survey of end users of all electronic information services (HE and FE), with Action research report. Final report 2002/2003 Cycle Four. Aberystwyth: Department of Information Studies, University of Wales Aberystwyth with Information Automation Ltd (CIQM). Sponsorship: JISC

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Thatcher, Rhys, et al., 'Influence of blood donation on O-2 uptake on-kinetics, peak O-2 uptake and time to exhaustion during severe-intensity cycle exercise in humans', Experimental Physiology (2006) 91(3) pp.499-509 RAE2008

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In a road network, cyclists are the group exposed to the maximum amount of risk. Route choice of a cyclist is often based on level of expertise, perceived or actual road risks, personal decisions, weather conditions and a number of other factors. Consequently, cycling tends to be the only significant travel mode where optimised route choice is not based on least-path or least-time. This paper presents an Android platform based mobile-app for personalised route planning of cyclists in Dublin. The mobile-app, apart from its immediate advantage to the cyclists, acts as the departure point for a number of research projects and aids in establishing some critical calibration values for the cycling network in Dublin. 

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Current building regulations are generally prescriptive in nature. It is widely accepted in Europe that this form of building regulation is stifling technological innovation and leading to inadequate energy efficiency in the building stock. This has increased the motivation to move design practices towards a more ‘performance-based’ model in order to mitigate inflated levels of energy-use consumed by the building stock. A performance based model assesses the interaction of all building elements and the resulting impact on holistic building energy-use. However, this is a nebulous task due to building energy-use being affected by a myriad of heterogeneous agents. Accordingly, it is imperative that appropriate methods, tools and technologies are employed for energy prediction, measurement and evaluation throughout the project’s life cycle. This research also considers that it is imperative that the data is universally accessible by all stakeholders. The use of a centrally based product model for exchange of building information is explored. This research describes the development and implementation of a new building energy-use performance assessment methodology. Termed the Building Effectiveness Communications ratios (BECs) methodology, this performance-based framework is capable of translating complex definitions of sustainability for energy efficiency and depicting universally understandable views at all stage of the Building Life Cycle (BLC) to the project’s stakeholders. The enabling yardsticks of building energy-use performance, termed Ir and Pr, provide continuous design and operations feedback in order to aid the building’s decision makers. Utilised effectively, the methodology is capable of delivering quality assurance throughout the BLC by providing project teams with quantitative measurement of energy efficiency. Armed with these superior enabling tools for project stakeholder communication, it is envisaged that project teams will be better placed to augment a knowledge base and generate more efficient additions to the building stock.

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Comfort is, in essence, satisfaction with the environment, and with respect to the indoor environment it is primarily satisfaction with the thermal conditions and air quality. Improving comfort has social, health and economic benefits, and is more financially significant than any other building cost. Despite this, comfort is not strictly managed throughout the building lifecycle. This is mainly due to the lack of an appropriate system to adequately manage comfort knowledge through the construction process into operation. Previous proposals to improve knowledge management have not been successfully adopted by the construction industry. To address this, the BabySteps approach was devised. BabySteps is an approach, proposed by this research, which states that for an innovation to be adopted into the industry it must be implementable through a number of small changes. This research proposes that improving the management of comfort knowledge will improve comfort. ComMet is a new methodology proposed by this research that manages comfort knowledge. It enables comfort knowledge to be captured, stored and accessed throughout the building life-cycle and so allowing it to be re-used in future stages of the building project and in future projects. It does this using the following: Comfort Performances – These are simplified numerical representations of the comfort of the indoor environment. Comfort Performances quantify the comfort at each stage of the building life-cycle using standard comfort metrics. Comfort Ratings - These are a means of classifying the comfort conditions of the indoor environment according to an appropriate standard. Comfort Ratings are generated by comparing different Comfort Performances. Comfort Ratings provide additional information relating to the comfort conditions of the indoor environment, which is not readily determined from the individual Comfort Performances. Comfort History – This is a continuous descriptive record of the comfort throughout the project, with a focus on documenting the items and activities, proposed and implemented, which could potentially affect comfort. Each aspect of the Comfort History is linked to the relevant comfort entity it references. These three components create a comprehensive record of the comfort throughout the building lifecycle. They are then stored and made available in a common format in a central location which allows them to be re-used ad infinitum. The LCMS System was developed to implement the ComMet methodology. It uses current and emerging technologies to capture, store and allow easy access to comfort knowledge as specified by ComMet. LCMS is an IT system that is a combination of the following six components: Building Standards; Modelling & Simulation; Physical Measurement through the specially developed Egg-Whisk (Wireless Sensor) Network; Data Manipulation; Information Recording; Knowledge Storage and Access.Results from a test case application of the LCMS system - an existing office room at a research facility - highlighted that while some aspects of comfort were being maintained, the building’s environment was not in compliance with the acceptable levels as stipulated by the relevant building standards. The implementation of ComMet, through LCMS, demonstrates how comfort, typically only considered during early design, can be measured and managed appropriately through systematic application of the methodology as means of ensuring a healthy internal environment in the building.

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Publication des peintures et inscriptions des murs nord et est du narthex de l'église rupestre du Deir Abou Hennis