Michael Buettner

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In this paper we present X-MAC, a low power MAC protocol for wireless sensor networks (WSNs). Standard MAC protocols developed for duty-cycled WSNs such as BMAC, which is the default MAC protocol for TinyOS, employ an extended preamble and preamble sampling. While this "low power listening" approach is simple, asynchronous, and energy-efficient, the long(More)
The availability of complete plant genomes has greatly influenced the identification and analysis of phylogenetically related gene clusters. In Arabidopsis, this has revealed the existence of a monosaccharide transporter(-like) gene family with 53 members, which play a role in long-distance sugar partitioning or sub-cellular sugar distribution and catalyze(More)
This paper examines the performance of EPC Class-1 Generation-2 UHF RFID reader systems in a realistic setting. Specifically, we identify factors that degrade overall performance and reliability with a focus on the physical layer, and we explore the degree to which reader configuration options can mitigate these factors. We use a custom software-radio based(More)
Mobile devices are increasingly the dominant Internet access technology. Nevertheless, high costs, data caps, and throttling are a source of widespread frustration, and a significant barrier to adoption in emerging markets. This paper presents Flywheel, an HTTP proxy service that extends the life of mobile data plans by compressing responses in-flight(More)
We explore a dense sensing approach that uses RFID sensor network technology to recognize human activities. In our setting, everyday objects are instrumented with UHF RFID tags called WISPs that are equipped with accelerometers. RFID readers detect when the objects are used by examining this sensor data, and daily activities are then inferred from the(More)
Computational RFID (CRFID) tags embed sensing and computation into the physical world. The operation of the tags is limited by the RF energy that can be harvested from a nearby power source. We present a CRFID runtime, Dewdrop, that makes effective use of the harvested energy. Dewdrop treats iterative tasks as a scheduling problem to balance task demands(More)
Guard cell chloroplasts are unable to perform significant photosynthetic CO2 fixation via Rubisco. Therefore, guard cells depend on carbon supply from adjacent cells even during the light period. Due to their reversible turgor changes, this import cannot be mediated by plasmodesmata. Nevertheless, guard cells of several plants were shown to use(More)
The vacuolar membrane is involved in solute uptake into and release from the vacuole, which is the largest plant organelle. In addition to inorganic ions and metabolites, large quantities of protons and sugars are shuttled across this membrane. Current models suggest that the proton gradient across the membrane drives the accumulation and/or release of(More)
The accumulation of sugars in grape berries requires the co-ordinate expression of sucrose transporters, invertases, and monosaccharide transporters. A monosaccharide transporter homologue (VvHT1, Vitis vinifera hexose transporter 1) has previously been isolated from grape berries at the veraison stage, and its expression was shown to be regulated by sugars(More)
We argue that sensing and computation platforms that leverage RFID technology can realize “smart-dust” applications that have eluded the sensor network community. RFID sensor networks (RSNs), which consist of RFID readers and RFID sensor nodes (WISPs), extend RFID to include sensing and bring the advantages of small, inexpensive and long-lived RFID tags to(More)