This paper considers the issues of scheduling and caching JPEG2000 data in client/server interactive browsing applications, under memory and channel bandwidth constraints. It analyzes how the conveyed data have to be selected at the server and managed within the client cache so as to maximize the reactivity of the browsing application. Formally, to render the dynamic nature of the browsing session, we assume the existence of a reaction model that defines when the user launches a novel command as a function of the image quality displayed at the client. As a main outcome, our work demonstrates that, due to the latency inherent to client/server exchanges, a priori expectation about future navigation commands may help to improve the overall reactivity of the system. In our study, the browsing session is defined by the evolution of a rectangular window of interest (WoI) along the time. At any given time, the WoI defines the position and the resolution of the image data to display at the client. The expectation about future navigation commands is then formalized based on a stochastic navigation model, which defines the probability that a given WoI is requested next, knowing previous WoI requests. Based on that knowledge, several scheduling scenarios are considered. The first scenario is conventional and transmits all the data corresponding to the current WoI before prefetching the most promising data outside the current WoI. Alternative scenarios are then proposed to anticipate prefetching, by scheduling data expected to be requested in the future before all the current WoI data have been sent out. Our results demonstrate that, for predictable navigation commands, anticipated prefetching improves the overall reactivity of the system by up to 30% compared to the conventional scheduling approach. They also reveal that an accurate knowledge of the reaction model is not required to get these significant improvements.
Accurate descriptions of feeding habits are essential to understanding the evolution of dietary preferences and the high levels of diversification within the Chrysomelidae. Both primary observations and summaries suggest that the cassidine beetle tribe, Cephaloleiini, is a species-rich group of feeding specialists on monocot hosts. However, accurate host ranges are poorly defined for most hispine beetle species. To better document occurrence and feeding, we censused the Cephaloleiini associated with rolled leaves of five species of Marantaceae and six species of Heliconiaceae (Zingiberales) in lowland Central Panama. Additionally, we conducted choice and no-choice feeding tests on a subset of both the plants and beetles encountered in the censuses. Both types of data suggest that most species of Cephaloleiini feed on a greater variety of related plant species than has previously been reported.
The image compression standard JPEG 2000 proposes a large set of features, useful for today's multimedia applications. Unfortunately, it is much more complex than older standards. Real-time applications, such as Digital Cinema, require a specific, secure and scalable hardware implementation. In this paper, a decoding scheme is proposed with two main characteristics. First, the complete scheme takes place in an FPGA, without accessing any external memory, allowing integration in a secured system. Second, a customizable level of parallelization allows to satisfy a broad range of constraints, depending on the signal resolution. The resulting architecture is therefore ready to meet upcoming Digital Cinema specifications.
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