Food And Agriculture In The Liberal Arts     

Connie Weil 《The Professional geographer》1984,36(2):243-244

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Current state and trends in Canadian Arctic marine ecosystems: II. Heterotrophic food web, pelagic-benthic coupling, and biodiversity     

Gérald Darnis  Dominique Robert  Corinne Pomerleau  Heike Link  Philippe Archambault  R. John Nelson  Maxime Geoffroy  Jean-éric Tremblay  Connie Lovejoy  Steve H. Ferguson  Brian P. V. Hunt  Louis Fortier 《Climatic change》2012,115(1):179-205

As part of the Canadian contribution to the International Polar Year (IPY), several major international research programs have focused on offshore arctic marine ecosystems. The general goal of these projects was to improve our understanding of how the response of arctic marine ecosystems to climate warming will alter food web structure and ecosystem services provided to Northerners. At least four key findings from these projects relating to arctic heterotrophic food web, pelagic-benthic coupling and biodiversity have emerged: (1) Contrary to a long-standing paradigm of dormant ecosystems during the long arctic winter, major food web components showed relatively high level of winter activity, well before the spring release of ice algae and subsequent phytoplankton bloom. Such phenological plasticity among key secondary producers like zooplankton may thus narrow the risks of extreme mismatch between primary production and secondary production in an increasingly variable arctic environment. (2) Tight pelagic-benthic coupling and consequent recycling of nutrients at the seafloor characterize specific regions of the Canadian Arctic, such as the North Water polynya and Lancaster Sound. The latter constitute hot spots of benthic ecosystem functioning compared to regions where zooplankton-mediated processes weaken the pelagic-benthic coupling. (3) In contrast with another widely shared assumption of lower biodiversity, arctic marine biodiversity is comparable to that reported off Atlantic and Pacific coasts of Canada, albeit threatened by the potential colonization of subarctic species. (4) The rapid decrease of summer sea-ice cover allows increasing numbers of killer whales to use the Canadian High Arctic as a hunting ground. The stronger presence of this species, bound to become a new apex predator of arctic seas, will likely affect populations of endemic arctic marine mammals such as the narwhal, bowhead, and beluga whales.  相似文献   

Characteristics of cirrus clouds and its radiative properties based on lidar observation over Chung-Li, Taiwan     

Subrata Kumar Das  Chih-Wei Chiang  Jan-Bai Nee 《Atmospheric Research》2009,93(4):723-735

In this paper, characterization of cirrus clouds are made by using data from ground based polarization lidar and radiosonde measurements over Chung-Li (24.58°N, 121.10°E), Taiwan for a period of 1999–2006. During this period, the occurrence of cirrus clouds is about 37% of the total measurement nights over the lidar site. Analysis of the measurement gives the statistical characteristics about the macrophysical properties such as occurrence height, ambient temperature, and its geometrical thickness while the microphysical properties are interpreted in terms of extinction coefficient, optical depth, effective lidar ratio and depolarization ratio. The effective lidar ratio has been retrieved by using the simulation technique of backscattered lidar signals. The effect of multiple scattering has been taken into the account by a model calculation. Summer (Jun–Aug) shows the maximum appearances of cirrus due to its formation mechanism. It is shown that tropopause cirrus clouds may occur with a probability of about 24%. These clouds are usually optically thin and having laminar in structure with some cases resembling the characteristics similar to that of polar stratospheric clouds (PSCs). The radiative properties of the cirrus clouds are also discussed in detail by the empirical equations with results show a positive feedback on any climate change.  相似文献   

Incorporating uncertainty into the estimation of biological reference points for a spiny lobster (Panulirus penicillatus) fishery     

Yi‐Jay Chang  Chi‐Lu Sun  Yong Chen  Su‐Zan Yeh  Wei‐Chuan Chiang 《新西兰海洋与淡水研究杂志》2013,47(1):429-442

The status of a fishery is often defined as the probability of fishing mortality rate exceeding a perilous level for long‐term sustainability. Lobster stock assessments are often subject to large uncertainty in input data and high levels of natural variability in lobster life history processes, which calls for incorporating uncertainty associated with both indicator and management reference points in an evaluation of biological risk of overfishing. Using a Monte Carlo simulation approach, we evaluated the impacts of uncertainty in modelling on the determination of the status of the Taitung spiny lobster (Panulirus penicillatus) fishery (Taiwan), which has not been quantitatively determined despite its commercial importance. The commonly used biological reference points derived from the per recruit model (F _0.1 the fishing mortality rate where the slope of the curve of yield‐per‐recruit model is 10% of the maximum slope and F _4Q%, the fishing mortality rate that reduces the expected egg production for a cohort of female lobsters to 40% of that produced in the absence of a fishery of the egg‐per‐recruit model) were influenced by uncertainties associated with lobster life history and fishery parameters. A large uncertainty in the current fishing mortality rate (F _cnr) and estimates of biological reference points (F _BRPs) increased the uncertainty in determining the risk of overexploitation throughout the confidence levels of the stochastic decision‐making framework. This simulation study suggests that the target reference point of F _40% is less sensitive to the input parameters’ uncertainty than F _0.1 We suggest a further evaluation of other F‐based references points and development of biomass‐based reference points before final selection and implementation for the management of the Taitung lobster fishery.  相似文献   

A novel strategy to determine the insurance and risk control plan for natural disaster risk management   总被引：2，自引：2，他引：0  

Cheng-Wu Chen  Chun-Pin Tseng  Wen-Ko Hsu  Wei-Ling Chiang 《Natural Hazards》2012,64(2):1391-1403

This study presents an extended framework for the analysis of economic effects of natural disaster risk management. It also attempts to define and evaluate the optimal insurance arrangements. A model, the economic utility constrained-maximization model, is proposed. The purpose of this study is to establish a strategy for determining an insurance and risk control plan in which consideration is given to balancing the economic effects (e.g., decrease in costs due to damage) by disaster mitigation. Furthermore, these values are compared with risk control actions for purposes of prioritization, to provide data to help evaluate the benefit of each risk control action. Disaster insurance policy premiums in contrast are based on actuarial data taken from situations in which risk control measures are not employed. This can make such contracts unfair to responsible enterprise managers who must take risk control measures. This represents an unfair aspect of insurance policies. Enterprise managers should be able to determine the optimum arrangement between natural disaster risk control and insurance given their budget limitations. The optimal strategies aim at the best applicability and balance between risk control and insurance capability for the enterprise manager. Risk control measures can generate several risk control options for enterprise managers. Premium discounts by insurers are given in this model.  相似文献   

Hazard management and risk design by optimal statistical analysis   总被引：2，自引：2，他引：0  

Cheng-Wu Chen  Kevin Fong-Rey Liu  Chun-Pin Tseng  Wen-Ko Hsu  Wei-Ling Chiang 《Natural Hazards》2012,64(2):1707-1716

Elicitation methods are used in decision making with respect to risk hazards to allow a researcher to infer the subjective utilities of outcomes from the observed preferences of an individual. A questionnaire method is presented, in this study, which takes into account the inevitable distortion of preferences by random errors and minimizes the effect of such errors. Under mild assumptions, the method for eliciting the utilities of many outcomes is a three-stage procedure. First, the questionnaire is utilized to elicit responses from which a subjective score is defined. Second, individual risk factors are discussed. Finally, the regression model presents individual risk preferences given the overall organizational risk culture, risk management policy, risk identification, and risk analysis. This paper addresses how company managers face risk and their tolerance of risk with respect to risk management.  相似文献   

Risk and uncertainty analysis in the planning stages of a risk decision-making process   总被引：7，自引：6，他引：1  

Wen-Ko Hsu  Chun-Pin Tseng  Wei-Ling Chiang  Cheng-Wu Chen 《Natural Hazards》2012,61(3):1355-1365

Natural disaster risk, a long-time concern in the insurance industry, is increasingly recognized as a present danger in the business strategies of risk control and enterprise management agencies. Floods and earthquakes can cause massive loss of life and infrastructure, resulting in business interruption and heavy casualties. Many of the short-term developmental strategies employed throughout the world have only served to exacerbate the impact of natural disasters. Therefore, this study presents a review of formal methods that are commonly used in risk and uncertainty analysis in planning and concludes with a critical assessment of the advantages and disadvantages of the different priority setting methods. Our focus is a preliminary proposal for developing an efficient probabilistic approach to facilitate design optimization that involves probabilistic constraints.  相似文献   

A fracture study by using bipole–bipole cross-well logging     

T.R. Guo  L.T. Tong  L.W. Chiang  C.H. Yang 《Journal of Applied Geophysics》2011,75(2):203-210

Electrical Resistivity Tomography (ERT) can provide images of subsurface electrical structure between two boreholes. Data quality control is a key issue before ERT inversion. However, there is no effective data quality control method on an ERT survey. In this paper, a method called common current gather for a bipole–bipole array (CCGbb) was proposed to check ERT data quality in a rapid way. Synthetic models were conducted to compare the response difference between pole–pole array and bipole–bipole array. A field work at granite area was tested to verify the applicability of the proposed CCGbb method. From the results of this study, we suggested that conducting CCGbb before ERT inversion and a cross-borehole tracer test for both field data quality control and possible water conducting fractures (WCFs) delineation.  相似文献   

Sedimentology of early Pliocene sandstones in the south-western Taiwan foreland: Implications for basin physiography in the early stages of collision     

Sébastien Castelltort  Stefan Nagel  Frédéric Mouthereau  Andrew Tien-Shun Lin  Andreas Wetzel  Boris Kaus  Sean Willett  Shao-Ping Chiang  Wei-Yi Chiu 《Journal of Asian Earth Sciences》2011,40(1):52-71

This work presents sedimentological observations and interpretations on three detailed sections of the Pliocene Yutengping/Ailiaochiao formations, deposited in the early stages of collision in Taiwan. Seven facies associations record paleoenvironments of deposition ranging from nearshore to lower offshore with a strong influence of tidal reworking, even in shelfal sub-tidal environments, and a pro-delta setting characterized by mass-flows. The association of shallow facies of the upper offshore to lower shoreface with pro-delta turbidite facies sourced in the orogen to the east suggests a peculiar setting in which turbidite deposition occurred below wave base but on the shelf, in water depths of probably less than 100 m. This adds to the examples of “shallow turbidites” increasingly commonly found in foreland basins and challenges the classical view of a “deep” early underfilled foreland basin. Time series analysis on tidal rhythmites allow us to identify a yearly signal in the form of periodic changes of sand-supply, energy and bioturbation that suggests a marked seasonality possibly affecting precipitation and sediment delivery as well as temperature. The Taiwan foreland basin may also present a potentially high-resolution record in shallow sediments of the early installation of monsoonal circulation patterns in east Asia. We confirm partly the paleogeography during the early stages of collision in Taiwan: the Chinese margin displayed a pronounced non-cylindrical geometry with a large basement promontory to the west in place of the modern Taiwan mountain range. Collision in Taiwan may have happened at once along the whole length of the modern mountain range, instead of progressively from north to south as classically considered.  相似文献   

Long-term (1998–2007) trends on the spatial distribution of heterotrophic ciliates in the East China Sea in summer: effect of the Three Gorges Dam construction     

An-Yi Tsai  Gwo-Ching Gong  Kuo-Ping Chiang  Chien-Fu Chao  Herng-Ru Guo 《Journal of Oceanography》2011,67(6):725-737

The spatial distribution of heterotrophic ciliates, environmental factors and potential food items (bacteria, Synechococcus spp. and nanoflagellates) were measured in the East China Sea to examine which variables contributed importantly to the long-term distribution of ciliates between 1998 and 2007. In July 1998 and June 2003, heterotrophic ciliates were found to be abundant (1,000–2,000 × 10³ cells m⁻³) in regions where surface salinity <32 but extremely low (<500 × 10³ cells m⁻³) in shelf waters of surface salinity >32. After August 2003, shortly after the completion of the Three Gorges Dam, we found no significant areal differences in the abundance of heterotrophic ciliates (HC). However, we found a significantly negative correlation between temperature and HC abundance of surface water after the completion of the dam, suggesting that temperature had a greater influence on HC abundance, once the original saline state had changed. For the long-term trends on the vertical distribution of HC, their abundance was significantly higher in the upper 50 m of the water column than at either 75 or 100 m. Abundance of Synechococcus spp. at these levels varied significantly in regions of surface salinity <32, suggesting that ciliates and picophytoplankton contribute greatly to mediating the transfer of organic matter to higher trophic levels in this marine ecosystem.  相似文献