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561.
The relationship between agricultural intensification and biological control: experimental tests across Europe 总被引:2,自引:0,他引:2
Thies C Haenke S Scherber C Bengtsson J Bommarco R Clement LW Ceryngier P Dennis C Emmerson M Gagic V Hawro V Liira J Weisser WW Winqvist C Tscharntke T 《Ecological applications》2011,21(6):2187-2196
Agricultural intensification can affect biodiversity and related ecosystem services such as biological control, but large-scale experimental evidence is missing. We examined aphid pest populations in cereal fields under experimentally reduced densities of (1) ground-dwelling predators (-G), (2) vegetation-dwelling predators and parasitoids (-V), (3) a combination of (1) and (2) (-G-V), compared with open-fields (control), in contrasting landscapes with low vs. high levels of agricultural intensification (AI), and in five European regions. Aphid populations were 28%, 97%, and 199% higher in -G, -V, and -G-V treatments, respectively, compared to the open fields, indicating synergistic effects of both natural-enemy groups. Enhanced parasitoid: host and predator: prey ratios were related to reduced aphid population density and population growth. The relative importance of parasitoids and vegetation-dwelling predators greatly differed among European regions, and agricultural intensification affected biological control and aphid density only in some regions. This shows a changing role of species group identity in diverse enemy communities and a need to consider region-specific landscape management. 相似文献
562.
Information technology and emergency management: preparedness and planning in US states 总被引:1,自引:0,他引:1
Christopher Reddick 《Disasters》2011,35(1):45-61
The purpose of this paper is to examine the impact of information technology (IT) on emergency preparedness and planning by analysing a survey of US state government departments of emergency management. The research results show that there has been a significant impact of IT on emergency planning. IT has proven to be effective for all phases of emergency management, but especially for the response phase. There are numerous technologies used in emergency management, ranging from the internet, Geographic Information Systems and wireless technologies to more advanced hazard analysis models. All were generally viewed as being effective. Lack of financial resources and support from elected officials is a perennial problem in public administration, and was found to be prevalent in this study of IT and emergency management. There was evidence that state governments rating high on a performance index were more likely to use IT for emergency management. 相似文献
563.
Diel swimming behaviors of juvenile anchovies (Anchoa spp.) were observed using stationary hydroacoustics and synoptic physicochemical and zooplankton profiles during four unique
water quality scenarios in the Neuse River Estuary, NC, USA. Vertical distribution of fish was restricted to waters with DO
greater than 2.5 mg O2 l−1, except when greater than 70% of the water column was hypoxic and a subset of fish were occupying water with 1 mg O2 l−1. We made the prediction that an individual fish would select a swim speed that would maximize net energy gain given the abundance
and availability of prey in the normoxic waters. During the day, fish adopted swim speeds between 7 and 8.8 bl s−1 that were near the theoretical optimum speeds between 7.0 and 8.0 bl s−1. An exception was found during severe hypoxia, when fish were swimming at 60% above the optimum speed (observed speed = 10.6 bl s−1, expected = 6.4 bl s−1). The anchovy is a visual planktivore; therefore, we expected a diel activity pattern characteristic of a diurnal species,
with quiescence at night to minimize energetic costs. Under stratified and hypoxic conditions with high fish density coupled
with limited prey availability, anchovies sustained high swimming speeds at night. The sustained nighttime activity resulted
in estimated daily energy expenditure over 20% greater than fish that adopted a diurnal activity pattern. We provide evidence
that the sustained nighttime activity patterns are a result of foraging at night due to a lower ration achieved during the
day. During severe hypoxic events, we also observed individual fish making brief forays into the hypoxic hypolimnion. These
bottom waters generally contained higher prey (copepod) concentrations than the surface waters. The bay anchovy, a facultative
particle forager, adopts a range of behaviors to compensate for the effects of increased conspecific density and reduced prey
availability in the presence of stratification-induced hypoxia. 相似文献
564.
Small mammals appear to be less vulnerable to extinction than large species, but the underlying reasons are poorly understood. Here, we provide evidence that almost all (93.5%) of 61 recently extinct mammal species were homeothermic, maintaining a constant high body temperature and thus energy expenditure, which demands a high intake of food, long foraging times, and thus exposure to predators. In contrast, only 6.5% of extinct mammals were likely heterothermic and employed multi-day torpor (hibernation) or daily torpor, even though torpor is widespread within more than half of all mammalian orders. Torpor is characterized by substantial reductions of body temperature and energy expenditure and enhances survival during adverse conditions by minimizing food and water requirements, and consequently reduces foraging requirements and exposure to predators. Moreover, because life span is generally longer in heterothermic mammals than in related homeotherms, heterotherms can employ a ‘sit-and-wait’ strategy to withstand adverse periods and then repopulate when circumstances improve. Thus, torpor is a crucial but hitherto unappreciated attribute of small mammals for avoiding extinction. Many opportunistic heterothermic species, because of their plastic energetic requirements, may also stand a better chance of future survival than homeothermic species in the face of greater climatic extremes and changes in environmental conditions caused by global warming. 相似文献
565.
This paper presents guidelines that can be used by managers of healthcare facilities to evaluate and assess the quality of resources and waste management at their facilities and enabling the principles of sustainable development to be addressed. The guidelines include the following key aspects which need to be considered when completing an assessment. They are: (a) general management; (b) social issues; (c) health and safety; (d) energy and water use; (e) purchasing and supply; (f) waste management (responsibility, segregation, storage and packaging); (g) waste transport; (h) recycling and re-use; (i) waste treatment; and (j) final disposal. They identify actions required to achieve a higher level of performance which can readily be applied to any healthcare facility, irrespective of the local level of social, economic and environmental development. The guidelines are presented, and the characteristics of facilities associated with sustainable (level 4) and unsustainable (level 0) healthcare resource and wastes management are outlined. They have been used to assess a major London hospital, and this highlighted a number of deficiencies in current practice, including a lack of control over purchasing and supply, and very low rates of segregation of municipal solid waste from hazardous healthcare waste. 相似文献
566.
Philip Andrews-Speed Armando Zamora Christopher D. Rogers Lei Shen Shelley Cao & Minying Yang 《Natural resources forum》2002,26(1):45-54
The effective management of small-scale mines is one of the major challenges for governments in the mining sector. Small-scale mining may bring tangible, short-term benefits to the communities involved. However, these benefits are frequently outweighed by the costs incurred in terms of illness, injury, pollution, waste of natural resources and market distortions. Governments, international agencies and advisers are generally able to draw up lists of actions which are required to regulate and manage small-scale mines more effectively, but turning plans into sustained action has proved more difficult. Two aspects of policy implementation are crucial to success: the alignment of interests, and the attitude and effectiveness of government. Using a case study of township and village coal mines in China, this article develops an approach to analysing these issues that could assist regional policy makers and advisers in formulating policy, in identifying key obstacles to policy implementation, and in identifying particular parties which need to be infiuenced or educated in order for the policy to succeed. 相似文献
567.
568.
569.
This paper discusses the design, testing and application of a new interlock system for field use with neutron generating bore hole probes at the Idaho National Engineering and Environmental Laboratory. Such probes produce 14 MeV neutrons at a yield up to 3×108 neutrons/s, and present an ionizing radiation hazard to personnel particularly when operated in an unshielded configuration. This interlock system prevents personnel from being exposed to the relatively high radiation fields caused by an unsafe condition when an operating neutron generator probe is withdrawn from a well in the ground. An electromechanical interlock prototype system has been designed, built and tested, and has been found to be effective at preventing this event. The design is simple, is effective in mitigating the hazard, and can be installed in minutes. The system could be modified to interlock radiation-generating devices other than neutron generators that are used in similar environments. 相似文献
570.
Sam Toan William ODell Christopher K. Russell Sun Zhao Qinghua Lai Huiping Song Ying Zhao Maohong Fan 《环境科学学报(英文版)》2019,31(4):74-80
Amine-basedcarbon-capture technologies have been shown to be energetically expensive and to cause significant environmental and epidemiological impacts due to their volatility.Bicarbonate formation from carbon dioxide's reaction with water has been suggested as an effective alternative for capturing CO_2;however,the thermodynamics of this reaction are not well understood.This study experimentally determined the equilibrium constant of sodium bicarbonate(Na HCO_3)decomposition to sodium,water,and carbon dioxide;the study also compared the equilibrium constant to theoretical calculations.Using a combination of experimentation and thermodynamic relationships,the unitless equilibrium constants of the forward and reverse reactions were calculated accurately(error±9%and±4%,respectively).Equilibrium data were calculated using enthalpy and entropy values of each component of Na HCO_3decomposition at temperatures ranging from 25 to 155°C respectively.These results offer more data essential to optimizing Na HCO_3use in environmentally friendly nextgeneration CO_2-capture technologies. 相似文献