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611.
Summary The three-dimensional structure of flocks of dunlin, Calidris alpina, and starlings, Sturnus vulgaris, was studied while birds were in transit between feeding, loafing and roosting sites. A technique was developed that uses standard photogrammetric methods to determine the three-coordinate position of birds in flocks from stereoscopic pairs of simultaneously exposed photographs. A comparison of nearest neighbour distances indicates that dunlin have a tighter, more compact flock structure than do starlings (Fig. 2; Table 2). Analysis of interbird angles in both the vertical and horizontal planes indicates that each dunlin's nearest neighbour is most likely to be behind and below it. This spatial structure results in areas in which few nearest neighbours occur (e.g., immediately in front and below) (Fig. 3). Flight speeds during transit flights are also presented (Table 4). The spatial structure and behaviour of dunlin and starling flocks appear to be very similar to the structure and behaviour of schools of fish. 相似文献
612.
William F. O'Brien M.D. Deborah Sternlicht Carol Torres Robert A. Knuppel Raul Montenegro 《黑龙江环境通报》1990,10(3):183-188
The value of determination of maternal serum of alpha-fetoprotein (MSAFP) concentration in i he second trimester is well established. In addition to open neural tube defects, pregnancies associated with elevated second-trimester MSAFP have been shown to be at increased risk for a variety of problems, including low birth weight, preterm delivery, and pregnancy-induced hypertension (PIH). We evaluated the potential usefulness of MSAFP in the early third trimester. MSAFP concentration was determined in over 200 women at the time of glucose screening. Results were analysed with regard to gestational age at sampling, maternal weight, race, diabetes, and presence of twins. MSAFP was twice as high in twin gestation, but not affected by race or the presence of diabetes. In contrast to levels in early gestation, third-trimester MSAFP does not appear to be predictive of preterm delivery, low birth weight, or PIH. 相似文献
613.
Methods for involving the public in natural resource management are changing as agencies adjust to an increasingly turbulent
social and political environment. There is growing interest among managers and scholars in collaborative approaches to public
involvement. Collaboration is conceptually defined and elaborated using examples from the natural resource management field.
This paper then examines how collaboration theory from the organizational behavior field can help environmental managers to
better understand those factors that facilitate and inhibit collaborative solutions to resource problems. A process-oriented
model is presented that proposes that collaboration emerges out of an environmental context and then proceeds sequentially
through a problem-setting, direction-setting, and structuring phase. Factors constraining collaboration are also specified,
including organizational culture and power differentials. Designs for managing collaboration are identified, which include
appreciative planning, joint agreements, dialogues, and negotiated settlements. Environmental managers need new skills to
manage collaboration within a dynamic social and political environment. Further research is needed to test the propositions
outlined here. 相似文献
614.
Lawrence B. Cahill 《环境质量管理》1994,3(4):457-467
As Total Quality Management (TQM) has become an important concept in learning how to manage environmental, health, and safety audit programs more effectively, an especially useful. TQM tool has been competitive benchmarking. Companies are using benchmarking studies to identify “best practices” that could be incorporated into their programs. In conducting benchmarking studies, evaluators often also identify the biggest common challenges facing audit program managers. This article discusses these best practices and biggest challenges associated with environmental audit programs. The conclusions are based on a number of benchmarking studies and third-party evaluations of corporate audit programs. As the sources are necessarily limited to the author's own experiences, there are no doubt many other specific best practices that are not discussed in this article. These will surface over time. 相似文献
615.
616.
Tobias J. Legler Zhong Liu Ariadni Mavrou Kirstin Finning Ilona Hromadnikova Silvia Galbiati Cathy Meaney Maj A. Hultén Francesco Crea Martin L. Olsson Deborah G. Maddocks Dorothy Huang Sylvia Armstrong Fisher Markus Sprenger-Haussels Aicha Ait Soussan C. Ellen van der Schoot 《黑龙江环境通报》2007,27(9):824-829
Objective Cell free foetal DNA (cff DNA) extracted from maternal plasma is now recognized as a potential source for prenatal diagnosis but the methodology is currently not well standardized. To evaluate different manual and automated DNA extraction methods with a view to developing standards, an International Workshop was performed. Methods Three plasma pools from RhD-negative pregnant women, a DNA standard, real-time-PCR protocol, primers and probes for RHD were sent to 12 laboratories and also to one company (Qiagen, Hilden, Germany). In pre-tests, pool 3 showed a low cff DNA concentration, pool 1 showed a higher concentration and pool 2 an intermediate concentration. Results The QIAamp DSP Virus Kit, the High Pure PCR Template Preparation Kit, an in-house protocol using the QIAamp DNA Blood Mini Kit, the CST genomic DNA purification kit, the Magna Pure LC, the MDx, the M48, the EZ1 and an in-house protocol using magnetic beads for manual and automated extraction were the methods that were able to reliably detect foetal RHD. The best results were obtained with the QIAamp DSP Virus Kit. The QIAamp DNA Blood Mini Kit showed very comparable results in laboratories that followed the manufacturer's protocol and started with ≥ 500 µL plasma. One participant using the QIAamp DNA Blood Midi Kit failed to detect reliably RHD in pool 3. Conclusions This workshop initiated a standardization process for extraction of cff DNA in maternal plasma. The highest yield was obtained by the QIAamp DSP Virus Kit, a result that will be evaluated in more detail in future studies. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
617.
618.
The dysgnathia complex (agnathia-otocephaly) (AO) is a lethal malformation that consists of congenital absence of the lower jaw with union or close approximation of the lower ears on the front of the neck, microstomia, and hypoglossia. We present a novel case of agnathia-otocephaly with associated organomegaly and the use of postmortem 3-D computed tomographic rendering. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
619.
Wanjun Liu Amar K. Mohanty Per Askeland Lawrence T. Drzal Manjusri Misra 《Journal of Polymers and the Environment》2008,16(3):177-182
Chemical modification of soy protein with monomers such as maleic anhydride, glycidyl methacrylate and styrene was accomplished
using reactive extrusion technology. Thermal and mechanical properties of the modified soy protein plastics were characterized
with differential scanning calorimetry (DSC), a dynamic mechanical analyzer (DMA) and a United Testing System load frame.
It was found that the denaturation temperature and the glass transition temperature of soy protein plastic changed. In addition,
the tensile properties of modified soy protein plastic improved. Attenuated total reflection Fourier transform infrared (ATR-FTIR)
and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure of modified soy proteins. A suggestion
of the interaction between soy protein and functional group in functional polymers is given. Through the in-situ interaction
between the polymer and soy protein plastic, the mechanical properties of the soy protein plastic can be adjusted and controlled. 相似文献
620.