Geochemical characterization and modeling of arsenic behavior in a highly contaminated mining soil     

Sara Bisone  Vincent Chatain  Denise Blanc  Mathieu Gautier  Rémy Bayard  Florence Sanchez  Rémy Gourdon 《Environmental Earth Sciences》2016,75(4):306

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Behaviour of crushed rock aggregates used in asphalt surface layer exposed to cold climate conditions     

Ana Patricia Pérez Fortes  Sara Anastasio  Elena Kuznetsova  Svein Willy Danielsen 《Environmental Earth Sciences》2016,75(21):1414

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Variation in the emission rate of sounds in a captive group of false killer whales <Emphasis Type="Italic">Pseudorca crassidens</Emphasis> during feedings: possible food anticipatory vocal activity?     

王丁  王克雄 《中国海洋湖沼学报》2016,34(6):1218-1237

This study examines whether a group of captive false killer whales (Pseudorca crassidens ) showed variations in the vocal rate around feeding times. The high level of motivation to express appetitive behaviors in captive animals may lead them to respond with changes of the behavioral activities during the time prior to food deliveries which are referred to as food anticipatory activity. False killer whales at Qingdao Polar Ocean World (Qingdao, China) showed significant variations of the rates of both the total sounds and sound classes (whistles, clicks, and burst pulses) around feedings. Precisely, from the Transition interval that recorded the lowest vocalization rate (3.40 s/m/d), the whales increased their acoustic emissions upon trainers’ arrival (13.08 s/m/d). The high rate was maintained or intensified throughout the food delivery (25.12 s/m/d), and then reduced immediately after the animals were fed (9.91 s/m/d). These changes in the false killer whales sound production rates around feeding times supports the hypothesis of the presence of a food anticipatory vocal activity. Although sound rates may not give detailed information regarding referential aspects of the animal communication it might still shed light about the arousal levels of the individuals during different social or environmental conditions. Further experiments should be performed to assess if variations of the time of feeding routines may affect the vocal activity of cetaceans in captivity as well as their welfare.  相似文献   

Explaining low yields and low food production in Cameroon: a farmers’ perspective     

Genesis Tambang Yengoh  Sara Brogaard 《GeoJournal》2014,79(3):279-295

While a bottom-up approach to identifying problems affecting food production among small-scale farmers has been urged as an appropriate means of finding sustainable solutions, few studies have determined the practical process of doing so and measured the outcomes of such an approach. This paper uses information gained mainly through focus groups with small-scale farmers and semi-structured interviews, to identify farmers’ perceptions of reasons behind low yields and low agricultural production in three communities of Cameroon’s North West region. Three biophysical factors are identified as the main reasons of low production: the long and more frequent dry spells and late start of the start of the rainy season. Three socio-economic reasons are identified as most important: land scarcity, money to invest in agriculture and labour scarcity. Farmers rank their reasons based on the importance to their agricultural production in their local area. Some of the important claims made by farmers are tested using field data and statistical analysis. These include the claims that: (1) the rainy season is increasingly starting later than it used to; and (2) the length of dry spells are increasingly longer than they used to be. The results of these statistical tests are significant, showing that farmers’ knowledge of some of the local problems affecting their activities can serve as an important input into formal research and policy design. Peoples’ understanding of a problem affects the way they will act on it—in terms of searching for solutions and implementing change. Farmers can therefore provide useful insights on why they think there are large yield gaps within their local production environments. The current agricultural development policy of the Cameroon government is advocating greater public–private engagement and can benefit from farmers’ inputs and opinions in the design of relevant policies. In the same light, nonlocal based researchers and research institutions can draw on farmers’ knowledge to create and accumulate knowledge on sustainable solutions to problems of low yields and low food production in Cameroon.  相似文献   

Terrestrial and Submerged Aquatic Vegetation Mapping in Fire Island National Seashore Using High Spatial Resolution Remote Sensing Data     

Yeqiao Wang  Michael Traber  Bryan Milstead  Sara Stevens 《Marine Geodesy》2013,36(1-2):77-95

The vegetation communities and spatial patterns on the Fire Island National Seashore are dynamic as the result of interactions with driving forces such as sand deposition, storm-driven over wash, salt spray, surface water, as well as with human disturbances. We used high spatial resolution QuickBird-2 satellite remote sensing data to map both terrestrial and submerged aquatic vegetation communities of the National Seashore. We adopted a stratified classification and unsupervised classification approach for mapping terrestrial vegetation types. Our classification scheme included detailed terrestrial vegetation types identified by previous vegetation mapping efforts of the National Park Service and three generalized categories of high-density seagrass, low-density seagrass coverages, and unvegetated bottom to map the submerged aquatic vegetation habitats. We used underwater videography, GPS-guided field reference photography, and bathymetric data to support remote sensing image classification and information extraction. This study achieved approximately 82% and 75% overall classification accuracy for the terrestrial and submnerged aquatic vegetations, respectively, and provided an updated vegetation inventory and change analysis for the Northeast Coastal and Barrier Network of the National Park Service.  相似文献   

High order normal form construction near the elliptic orbit of the Sitnikov problem     

Sara Di Ruzza  Christoph Lhotka 《Celestial Mechanics and Dynamical Astronomy》2011,111(4):449-464

We consider the Sitnikov problem; from the equations of motion we derive the approximate Hamiltonian flow. Then, we introduce suitable action–angle variables in order to construct a high order normal form of the Hamiltonian. We introduce Birkhoff Cartesian coordinates near the elliptic orbit and we analyze the behavior of the remainder of the normal form. Finally, we derive a kind of local stability estimate in the vicinity of the periodic orbit for exponentially long times using the normal form up to 40th order in Cartesian coordinates.  相似文献   

Kriging Prediction Intervals Based on Semiparametric Bootstrap   总被引：1，自引：0，他引：1  

Lina Schelin  Sara Sjöstedt-de Luna 《Mathematical Geosciences》2010,42(8):985-1000

Kriging is a widely used method for prediction, which, given observations of a (spatial) process, yields the best linear unbiased predictor of the process at a new location. The construction of corresponding prediction intervals typically relies on Gaussian assumptions. Here we show that the distribution of kriging predictors for non-Gaussian processes may be far from Gaussian, even asymptotically. This emphasizes the need for other ways to construct prediction intervals. We propose a semiparametric bootstrap method with focus on the ordinary kriging predictor. No distributional assumptions about the data generating process are needed. A simulation study for Gaussian as well as lognormal processes shows that the semiparametric bootstrap method works well. For the lognormal process we see significant improvement in coverage probability compared to traditional methods relying on Gaussian assumptions.  相似文献