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42.
Hodgkin–Huxley model, describing generation of action potentials in axons’ membranes, has been used for appreciation of the possible mechanisms of electromagnetic fields influence on neurons’ electrical activity. It follows from the carried calculations that flowing through an axon of the external current pulses, which have an area of rise, an area of DC, and an area of drop, does not influence own excitation pulses passage if periods of rise and drop are slope enough. Depending on the external current parameters, own excitation pulses may not be influenced or may be suppressed at greater velocity of rise and drop of an external current. Moreover, induced excitation pulses appear at definite parameters of an external current. In the case, when at passage through an axon of an external current, own excitation pulses follow one by one (paired pulse facilitation), and the second pulse may be suppressed if its level will not be increased additionally in comparison with the case of an external current absence. It is possible that such increase happens “automatically” as a result of “tuning” (adaptation) of axons to the conditions of flowing through them of an external current. It may be an explanation of the phenomena observed in experiments.  相似文献   
43.
The formation of perfluorooctanoate (PFOA) from 1H,1H,2H,2H-perfluorodecanol (8:2 FTOH) was studied for the first time in laboratory experiments with brackish water. The water samples were collected from the Baltic Sea, which is one of the largest brackish water areas in the world and is polluted with PFOA and other perfluorinated compounds. The formation of PFOA was studied in closed-bottle experiments at different water temperatures. As a reference experiment, a modified OECD 310 test was conducted with sludge from a wastewater treatment plant and with brackish water. The PFOA and 8:2 FTOH were concentrated from water samples by solid-phase extraction (SPE) and were analysed using liquid chromatography–mass spectrometry. The effect of oxygen concentration on the formation of PFOA was studied using surface water samples with high and low oxygen contents. Other experiments were performed with oxygen-rich surface water and oxygen-deficient bottom water. The formation of PFOA was observed in all experiments; it was higher in the trial performed with brackish water than in the reference test carried out with sludge. Clear temperature dependence was observed in the formation of PFOA in brackish water tests; after a 30-day test period, a sixfold increase was observed in the amount of PFOA in surface water between the temperatures of 15 and 20 °C. Microbes were suggested as the major cause of the formation of PFOA, but other environmental characteristics, such as oxygen, could also affect the formation potential of PFOA.  相似文献   
44.
In order to take up the twin challenge of reducing carbon dioxide (CO2) emissions, while meeting a growing energy demand, the potential deployment of carbon dioxide capture and storage (CCS) technologies is attracting a growing interest of policy makers around the world. In this study we evaluate and compare national approaches towards the development of CCS in the United States, Canada, Norway, the Netherlands, and Australia. The analysis is done by applying the functions of innovation systems approach. This approach posits that new technology is developed, demonstrated and deployed in the context of a technological innovation system. The performance assessment of the CCS innovation system shows that the extensive knowledge base and knowledge networks, which have been accumulated over the past years, have not yet been utilized by entrepreneurs to explore the market for integrated CCS concepts linked to power generation. This indicates that the build-up of the innovation system has entered a critical phase that is decisive for a further thriving development of CCS. In order to move the CCS innovation system through this present difficult episode and deploy more advanced CCS concepts at a larger scale; it is necessary to direct policy initiatives at the identified weak system functions, i.e. entrepreneurial activity, market creation and the mobilization of resources. Moreover, in some specific countries it is needed to provide more regulatory guidance and improve the legitimacy for the technology. We discuss how policy makers and technology managers can use these insights to develop a coherent policy strategy that would accelerate the deployment of CCS.  相似文献   
45.
Along term ecological research was carried out in a Hungarian oak forest, in "Bükk" National Park starting with 1972. During the faunistical studies 3,602 insect species and more than 200,000 individuals were collected. The dominant orders were Coleoptera (1,051 species), Lepidoptera (803 species), Hymenoptera (470 species) and Diptera (400 species). The relative species abundance (RSA) for all insects collected in all years of sampling period suggests a rather J shape curve than a not clear scaling property. This means that we were able to identify almost three quarters of the insect species from one ha European oak forest during the survey (from 1987 to 2003), and two third of the staphylinides expected. Considering the staphylinid fauna a total number of 160 species and 4,022 individuals were collected. The most widely occurring species in dominance order were: Ocypus biharicus, Pseudocypus mus, Atheta gagatina, Philonthus quisquiliarius, Oxypoda acuminate, Platydracus chalcocephalus, Atheta crassicomis, Latrimaeum atrocephalum, Haploglossa puncticollis, Philonthus succicola and Anotylus mutator. The pooled value of alpha diversity was 1.51. The Shannon-Weiner Index (H') was relatively high (3.29) in comparison with other studies.  相似文献   
46.
In 1988 I published a paper “Electromagnetic fields—a new ecological factor” (Markov 1988). There was no internet and very few cell phones were available. It was not even fear from the hazard of the power lines. However, I want to cite the beginning of this paper: “The contemporary conditions of life put man in dependence of the complex of physical influences on the environment and in the first place—of the electromagnetic fields. The rapid development of science and technology has resulted in the introduction of many new devices and technologies in industry, agriculture, and everyday life. On the other hand, during their phylogenetic and ontogenic development, the living organisms are continuously exposed to the influence of different biotic and abiotic factors. The physical factors are included in the first group, and the entire evolution of life is connected with an adaptation to the action of these factors.” Could I repeat this statement nearly a quarter of century later? Sure, I will. The only difference would be that I will speak not only for electromagnetic fields, but for green-house effects, global warming, volcano eruption, and radiation disasters. I would also discuss the noise and vibration to which people are exposed from early days to the very end of their life traveling with private vehicles or public transport.  相似文献   
47.
The improvement of safety in the process industries is related to assessment and reduction of risk in a cost-effective manner. This paper addresses the trade-off between risk and cost related to standby safety systems. An age-dependent unavailability model that integrates the effects of the test and maintenance (T&M) activities as well as component ageing is developed and represents the basis for calculating risk. The repair “same-as-new” process is considered regarding the T&M activities. Costs are expressed as a function of the selected risk measure. The time-averaged function of the selected risk measure is obtained from probabilistic safety assessment, i.e. the fault tree analysis. This function is further extended with inclusion of additional parameters related to T&M activities as well as ageing parameters related to component ageing. In that sense, a new model of system unavailability, incorporating component ageing and T&M costs, is presented. The testing strategy is also addressed. Sequential and staggered testings are compared. The developed approach is applied on a standard safety system in nuclear power plant although the method is applicable to standby safety systems that are tested and maintained in other industries as well. The results show that the risk-informed surveillance requirements differ from existing ones in technical specifications, which are deterministically based. Moreover, the presented approach achieves a significant reduction in system unavailability over a relatively small increase of total T&M costs.  相似文献   
48.
The empirical literature reports conflicting findings on the relation between environmental policy and environmental innovation: environmental policy both encourages and impedes environmental innovation, resulting in competing theoretical explanations. To find a way out of this counterproductive debate requires new and complementary insights into the effects of different policy instruments. This research therefore advances an approach in which a set of specific policy instruments as well as firms’ behavior regarding CHP (cogeneration of heat and power) adoption are considered as two distinct factors explaining environmental innovation in the Dutch paper and board industry. Using a longitudinal research design, the focus was not on any single policy instrument but on the accumulation of policy instruments. In addition, we studied intra-organizational factors influencing the adoption decision.Overall, we can conclude that paper and board factories perceive governmental environmental policies to be relevant, but that this constitutes just one of the factors influencing adoption processes, next to intra-organizational factors. The relative importance of such policies varies over time and per adoption process. The role of top-down regulation appears to be limited, whereas interactive regulation turned out to be important for several factories in the latest period of adoption. Positive economic instruments were important in almost all adoption processes, but were not and will never be the most important reason for adoption. The most important reason for CHP adoption appears to be high energy prices in combination with cost price reduction or the threat of additional regulation. For future policies, we recommend the implementation of a specific mixture of policy instruments, attuned to the specific industry and reinforcing each other. Moreover, goals should be consistent over time to avoid risk-averse behavior.  相似文献   
49.
For the antitropical gooseneck barnacle Pollicipes elegans, population-specific physiological temperature tolerance of larvae may serve as a barrier to larval dispersal across the warmest regions of the tropical Pacific Ocean. Thermal tolerance ranges of larvae of three different populations of P. elegans sampled in 2011 and 2012 (Mexico [MX], El Salvador [ES], and Peru [PE]) were investigated by measuring three indicators of physiological performance: swimming activity, oxygen consumption, and lethality or LT50. The thermal tolerance profiles, which include measurable optimum (maximum aerobic performance), pejus (“getting worse”) and pessimum (worst aerobic performance) ranges, of larvae from the three populations were consistent with their characteristic environmental temperatures. In MX, larvae live close to the upper border of their optimum during warm months and so have a limited capacity to tolerate higher-than-normal temperatures. Larvae from the ES population likewise appear to live within their optimum temperature range, but these larvae lack a detectable pessimum range, suggesting they would be unable to cope with temperatures above their pejus range. Larvae from PE have a broad optimum but no pejus range. Different thermal tolerance ranges provide strong evidence for population-dependent physiological adaptations in P. elegans. For the southern (PE) and northern (MX) P. elegans populations, high tropical temperatures are likely to be a strong direct physiological barrier to larval survival and dispersal, which is in contrast to the more thermally tolerant ES population.  相似文献   
50.
There is a growing interest in analyzing the possibility for current nuclear power plants operation extension. In that sense, life management programs, considering safety components ageing, are being developed and employed. On the other side, the large uncertainties of the ageing parameters as well as the uncertainties associated with most of the reliability data collections are widely acknowledged.This paper deals with uncertainty analysis associated with specific ageing rates database. The analysis is conducted using an analytical unavailability model applied for a selected safety system in a nuclear power plant. The most important problem is the immense uncertainty associated to the component ageing data sets as well as the lack of the very data in general, which would correspond to the more detailed modelling of ageing.New probability distributions, encompassing the ageing rates available in the considered data set, are suggested. The obtained results indicate the extent to which the uncertainty of the considered ageing data set, given the inherently assigned probability distribution, influences the performed unavailability calculations. Additionally, comparative analysis regarding the insights gained out of the application of the suggested probability distributions is conducted.  相似文献   
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