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Advances in processor, memory, and radio technology will enable small and cheap nodes capable of sensing, communication, and computation. Networks of such nodes can coordinate to perform distributed sensing of environmental phenomena. In this paper, we explore the <i>directed-diffusion</i> paradigm for such coordination. Directed diffusion is data-centric(More)
Energy is a critical resource in sensor networks. MAC protocols such as S-MAC and T-MAC coordinate sleep schedules to reduce energy consumption. Recently, lowpower listening (LPL) approaches such as WiseMAC and B-MAC exploit very brief polling of channel activity combined with long preambles before each transmission, saving energy particularly during low(More)
A distinguishing characteristic of wireless sensor networks is the opportunity to exploit characteristics of the application at lower layers. This approach is encouraged by device resource constraints, and acceptable because devices are inexpensive and numerous enough that they can be dedicated to specific applications. Many data dissemination protocols(More)
In most distributed systems, naming of nodes for low-level communication leverages topological location (such as node addresses) and is independent of any application. In this paper, we investigate an emerging class of distributed systems where low-level communication does not rely on network topological location. Rather, low-level communication is based on(More)
We use archaeological data and spatial methods to reconstruct the dispersal of farming into areas of sub-Saharan Africa now occupied by Bantu language speakers, and introduce a new large-scale radiocarbon database and a new suite of spatial modelling techniques. We also introduce a method of estimating phylogeographic relationships from(More)
Wireless sensor networks represent an increasingly important example of distributed event systems. Unlike Internet-based distributed event systems, sensor networks are very bandwidth constrained and use sensor nodes that are often dedicated to the network and controlled by a single organization. Bandwidth constraints require, and administrative homogeneity(More)
Traditional sensing models assume one or a few powerful sensors and centralized computation. Today, technological trends enable the creation of inexpensive, small, intelligent devices for sensing and actuation. If many small sensors can work together as a sensor network, they provide several advantages over traditional centralized sensing. By placing the(More)
This work presents models characterizing failures observed during the execution of large scientific applications on Amazon EC2. Scientific workflows are used as the underlying abstraction for application representations. As scientific workflows scale to hundreds of thousands of distinct tasks, failures due to software and hardware faults become increasingly(More)
The period from the late third millennium BC to the start of the first millennium AD witnesses the first steps towards food globalization in which a significant number of important crops and animals, independently domesticated within China, India, Africa and West Asia, traversed Central Asia greatly increasing Eurasian agricultural diversity. This paper(More)