94 resultados para user preferences
Resumo:
Demand for local food in the United States has significantly increased over the last decade. In an attempt to understand the drivers of this demand and how they have changed over time, we investigate the literature on organic and local foods over the last few decades. We focus our review on studies that allow comparison of characteristics now associated with both local and organic food. We summarize the major findings of these studies and their implications for understanding drivers of local food demand. Prior to the late 1990s, most studies failed to consider factors now associated with local food, and the few that included these factors found very little support for them. In many cases, the lines between local and organic were blurred. Coincident with the development of federal organic food standards, studies began to find comparatively more support for local food as distinct and separate from organic food. Our review uncovers a distinct turn in the demand for local and organic food. Before the federal organic standards, organic food was linked to small farms, animal welfare, deep sustainability, community support, and many other factors that are not associated with most organic foods today. Based on our review, we argue that demand for local food arose largely in response to corporate cooptation of the organic food market and the arrival of “organic lite.” This important shift in consumer preferences away from organic and toward local food has broad implications for the environment and society. If these patterns of consumer preferences prove to be sustainable, producers, activists, and others should be aware of the implications that these trends have for the food system at large.
Resumo:
Where users are interacting in a distributed virtual environment, the actions of each user must be observed by peers with sufficient consistency and within a limited delay so as not to be detrimental to the interaction. The consistency control issue may be split into three parts: update control; consistent enactment and evolution of events; and causal consistency. The delay in the presentation of events, termed latency, is primarily dependent on the network propagation delay and the consistency control algorithms. The latency induced by the consistency control algorithm, in particular causal ordering, is proportional to the number of participants. This paper describes how the effect of network delays may be reduced and introduces a scalable solution that provides sufficient consistency control while minimising its effect on latency. The principles described have been developed at Reading over the past five years. Similar principles are now emerging in the simulation community through the HLA standard. This paper attempts to validate the suggested principles within the schema of distributed simulation and virtual environments and to compare and contrast with those described by the HLA definition documents.
Resumo:
The preparation, the IR and ligand field spectra and the structures of the mixed-ligand addition compounds [(N,N-dimethyl-1,2-diaminoethane)bis(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)cobalt(II)], [Co(thtf)2me2en], and [(N,N,N′,N′-tetramethyl-1,2-diaminoethane)bis(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)cobalt(II)], [Co(thtf)2me4en], are reported. The structures were determined by single crystal X-ray diffraction analysis (monoclinic, space group P21/c, Z=4 with a=10.708(6), b=19.531(6), c=13.352(6) Å, β=111.64(10)°, R1=0.0642 and wR2=0.1719 for [Co(thtf)2(me2en)] and a=12.033(6), b=15.565(6), c=15.339(6) Å, β=92.57(6)°, R1=0.0612 and wR2=0.1504 for [Co(thtf)2me4en]). The structures are distorted octahedral and the shortest cobalt–cobalt separation distances are 5.388(2) Å in [Co(thtf)2me2en] and 8.675(3) Å in [Co(thtf)2me4en]. In both compounds the diamine molecules attain the gauche conformation. The U(Z,Z) conformation of the β-dione leads to a semi-chair conformation of the β-dionato chelate rings. The relative orientation of the groups attached to the β-dionato moiety depends on the extent of stereoelectronic effects the N-substitution of the diamine entails. In [Co(thtf)2me2en] the intraligand distance separating the trifluoromethyl carbon atoms is 5.281(18) Å while in [Co(thtf)2me2en] it increases to 8.338(9) Å. The cobalt–cobalt separation distance, the orientation of the chelate rings and the extent of N-substitution seem to affect hydrogen bonding. While in [Co(thtf)2me2en] inter- and intraligand hydrogen bonding is implicated, it is totally absent in [Co(thtf)2me4en].
Resumo:
User-generated content (UGC) is attracting a great deal of interest - some of it effective, some misguided. This article reviews the marketing-related factors that gave rise to UGC, tracing the relevant development of market orientation, social interaction, word of mouth, brand relationships, consumer creativity, co-creation, and customization, largely through the pages of the Journal of Advertising Research over the last 40 (or so) of its 50 years. The authors then discuss the characteristic features of UGC and how they differ from (and are similar to) these concepts. The insights thus gained will help practitioners and researchers understand what UGC is (and is not) and how it should (and should not) be used.