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61.
The main objective of the European Water Framework Directive (WFD) is the achievement of a good ecological and chemical status of the water environment (water bodies). This status corresponds to the limit value of Germany's Working Group of the Federal States on Water Problems Issues (LAWA) for water quality class II (3 mg/l total nitrogen). The rivers in the intensively cropped Upper Ems River basin (northwestern Germany) show total nitrogen concentrations in excess of 5–10 mg/l. Hence, the objective of our study was to find a land use and land management scenario that would reduce the total nitrogen concentration to meet the WFD requirements for good ecological and chemical status. We developed consecutive land use and management scenarios on the basis of policy instruments such as the support of agro-environmental measures by Common Agricultural Policy and regional landscape development programs. The model simulations were done by using the Soil and Water Assessment Tool (SWAT). Results of SWAT scenario calculations showed that drastic measures, which are unrealistic from a socio-economic point of view, would be needed to achieve the water quality target in the basin (reduction of arable land from 77.2% to 46% [13% organic farming], increase of pasture from 4% to 15%, afforestation from 10% to 21%, increase of protected wetlands from 0% to 9%, etc.). The example shows additionally that the achievement of the WFD targets is only possible with a consideration of regional landscape and land use distinctions. A related problem yet to be addressed is the general lack of measured water quality data with which to calibrate and validate water quality models such as SWAT. This adds considerable uncertainty to already complicated and uncertainty situations. Thus, improved strategies for water quality monitoring, and data accessibility must be established. 相似文献
62.
Hanspeter Wieland Stefan Giljum Martin Bruckner Anne Owen Richard Wood 《Economic Systems Research》2018,30(1):61-84
Recent empirical assessments revealed that footprint indicators calculated with various multi-regional input–output (MRIO) databases deliver deviating results. In this paper, we propose a new method, called structural production layer decomposition (SPLD), which complements existing structural decomposition approaches. SPLD enables differentiating between effects stemming from specific parts in the technology matrix, e.g. trade blocks vs. domestic blocks, while still allowing to link the various effects to the total region footprint. Using the carbon footprint of the EU-28 in 2011 as an example, we analyse the differences between EXIOBASE, Eora, GTAP and WIOD. Identical environmental data are used across all MRIO databases. In all model comparisons, variations in domestic blocks have a more significant impact on the carbon footprint than variations in trade blocks. The results provide a wealth of information for MRIO developers and are relevant for policy makers designing climate policy measures targeted to specific stages along product supply chains. 相似文献
63.
Although product placement research differentiates between specific placement effects, the placement of Brands and Brand information, which goes far beyond the mere presence of brands in media entertainment, are simply not taken into account. We assume that this form of product placement can generate knowledge and produce a learn effect. Actual insights on the cognitive effect of product placements, brand knowledge and Neurobiology, working theories and a Hypothesis on the growing knowledge gap, only go to reinforce this assumption and confirm that the learn effect through factors such as brand know-how, relevance, education and attractiveness of the media protagonist can be influenced. The results of an experiment in which audio-visual stimulus material was presented with or without placement showed the the information placed was recognized, remembered and therefore learned. While brand know-how and relevance have no influence on the intensity of this learn effect, attractive and well educated protagonists contributed to strengthen memory performance. 相似文献
64.
Stefan Ambec Corinne Langinier Stéphane Lemarié 《American journal of agricultural economics》2008,90(2):379-391
To reduce the competition from farmers who self-produce seed, an inbred line seed producer can switch to nondurable hybrid seed. In a two-period framework, we first investigate the impact of crop durability on self-production, pricing and switching decisions. Second, we study how the introduction of a fee paid by self-producing farmers affects those decisions. We find that the monopolist may produce technologically dominated hybrid seed in order to extract more surplus from farmers. Further, the introduction of a self-production fee improves efficiency. 相似文献
65.
Paul E. Ketelaar Stefan F. Bernritter Jonathan van't Riet Arief Ernst Hühn Thabo J. van Woudenberg Barbara C. N. Müller 《国际广告杂志》2017,36(2):356-367
Research on location-based advertising (LBA) suggests that the merits of LBA lie in the fact that consumers can be targeted with location-congruent ads on their personal mobile devices. However, LBA consists of two underlying constructs: a mobile (vs. point-of-sales) advertising medium and location congruency (vs. location incongruency). This study aims to disentangle these underlying constructs by showing that they differentially affect the efficacy of an ad. Using a virtual reality lab experiment, this study shows that location-congruent ads result in increased choice for the target brand as compared to location-incongruent ads, independent of medium type. However, in location-incongruent situations, mobile ads attracted more attention than point-of-sales display ads. The advantages of LBA thus do not seem to emanate from medium type, but rather from the congruency between the ad and product location. When the ad is received at a different location than the product, the mobile medium is able to enhance consumers' ad attention. 相似文献
66.
Stefan Linnhoff 《Journal of Strategic Marketing》2017,25(7):581-617
Increased engagement with mobile apps is an emerging trend with people today. Mobile devices have become so personalized that many people consider their mobile device as an extension of themselves. Research has suggested that one driving factor in a person’s adoption of mobile apps is the pursuit of happiness. However, there is little research regarding the influence of apps on a person’s well-being. The purpose of this paper was to examine mobile app usage among college students and the relationship between app usage and one’s satisfaction with life. Findings suggest that there is a correlation between mobile app usage and a person’s level of satisfaction with life. Gender differences in app usage were also found. 相似文献
67.
Daniel Scott Stefan Gössling C. Michael Hall Paul Peeters 《Journal of Sustainable Tourism》2016,24(1):52-72
Global leaders agree on the need to substantially decarbonize the global economy by 2050. This paper compares potential costs associated with different policy pathways to achieve tourism sector emission reduction ambitions (?50% by 2035) and transform the sector to be part of the mid-century decarbonized economy (?70% by 2050). Investment in emissions abatement within the tourism sector, combined with strategic external carbon offsets, was found to be approximately 5% more cost effective over the period 2015–2050 than exclusive reliance on offsetting. The cost to achieve the ?50% target through abatement and strategic offsetting, while significant, represents less than 0.1% of the estimated global tourism economy in 2020 and 3.6% in 2050. Distributed equally among all tourists (international and domestic), the cost of a low-carbon tourism sector is estimated at US$11 per trip, equivalent to many current travel fees or taxes. Exclusive reliance on offsetting would expose the sector to extensive and continued carbon liability costs beyond mid-century and could be perceived as climate inaction, increasing reputational risks and the potential for less efficient regulatory interventions that could hinder sustainable tourism development. Effective tourism sector leadership is needed to develop a strategic tourism policy framework and emission measurement and reporting system. 相似文献
68.
A framework for the detection of change points in the expectation in sequences of random variables is presented. Specifically, we investigate time series with general distributional assumptions that may show an unknown number of change points in the expectation occurring on multiple time scales and that may also contain change points in other parameters. To that end we propose a multiple filter test (MFT) that tests the null hypothesis of constant expectation and, in case of rejection of the null hypothesis, an algorithm that estimates the change points.The MFT has three important benefits. First, it allows for general distributional assumptions in the underlying model, assuming piecewise sequences of i.i.d. random variables, where also relaxations with regard to identical distribution or independence are possible. Second, it uses a MOSUM type statistic and an asymptotic setting in which the MOSUM process converges weakly to a functional of a Brownian motion which is then used to simulate the rejection threshold of the statistical test. This approach enables a simultaneous application of multiple MOSUM processes which improves the detection of change points that occur on different time scales. Third, we also show that the method is practically robust against changes in other distributional parameters such as the variance or higher order moments which might occur with or even without a change in expectation. A function implementing the described test and change point estimation is available in the R package MFT. 相似文献
69.
70.
Stefan Gössling 《Journal of Sustainable Tourism》2018,26(2):292-306
Learning is often a central element of tourism. Tourists can learn actively, i.e. with a specific purpose, as well as passively through the comparison of values, norms and customs. It has been argued that travel supports active learning that has positive outcomes for sustainability, for instance, in the context of conservation. Yet, the complexity of active and passive learning processes and their outcomes for environmental sustainability and sustainable lifestyles remain insufficiently understood. Against this background, the paper discusses selected learning outcomes for transportation (air travel), accommodation (hotels) and activities (theme park visits). Findings suggest that “desirable” learning (defined as pro-sustainable development learning) in tourism may be very limited, while in particular, passive learning processes which redefine social norms frequently have outcomes that are largely detrimental to sustainable lifestyles. They include forms of moral licensing, the diffusion of responsibilities as well as the attenuation of the negative consequences of travel. Given the economic, social and cultural importance of tourism vís-a-vís its global implications for environmental sustainability, learning outcomes in tourism deserve to be studied in greater detail, while strategies need to be devised to enhance sustainable learning effects. 相似文献