Abstract-We study the problem of information brokerage in sensor networks, where information consumers (sinks, users) search for data acquired by information producers (sources). In-network storage such as geographical hash table (GHT) has been proposed to store data at rendezvous nodes for consumers to retrieve. In this paper, we propose a double rulings scheme which stores data replicas on a curve instead of one or multiple isolated sensors. The consumer travels along another curve which is guaranteed to intersect the producer curve. The double rulings is a natural extension of the flat hashing scheme such as GHTs. It has improved query locality, i.e., consumers close to producers find the data quickly, and structured aggregate queries, i.e., a consumer following a curve is able to retrieve all the data. Further, by the flexibility of retrieval mechanisms we have better routing robustness (as multiple retrieval paths are available) and data robustness against regional node failures. We show by simulation that the double rulings scheme provides reduced communication costs and more balanced traffic load on the sensors.
Radio frequency~i dentification (RFIDW is a technology where a reader device can "sense" the presence of a closeby object by reading a tag device attached to the object. To improve coverage, multiple RFID readers can be deployed in the given region. In this paper, we consider the problem of slotted scheduled access of RFID tags in a multiple reader environment.In particular, we develop centralized algorithms in a slotted time model to read all the tags using near-optimal number ot time slots. We consider two scenariosone wherein the tag distribution in the physical space is unknown, and the other where tag distribution is known or can be estimated a priori. For each ot these scenarios, we consider two cases depending on whether a single channel or multiple channels are available. All the above version of the problem are NP-hard. We design approximation algorithms for the single channel and heuristic algorithms for the multiple channel cases. Through extensive simulations, we show that for the single channel case, our heuristics perform close to the approximation algorithms. In general, our simulations show that our algorithms significantly outperform Colorwave, an existing algorithm for similar problems.
BackgroundHuman papillomavirus (HPV) infection is the main etiological factor for the development of cervical cancer. Here we assessed the prevalence and distribution of HPV genotypes in Fujian population.MethodsA total of 8678 women aging from 17 to 84 years olds were recruited from the Fujian Medical University Union Hospital in Fujian Province. Every woman had a face-to-face interview. Cervical samples were collected from each participant and HPV screening was conducted using microarray hybridization.ResultsOur study showed that the HPV prevalence in Fujian province was 38.3%. Among the positive individuals, 70.6% were detected for single HPV infection, 29.4% for multiple HPV infections. Further analysis showed that the prevalence of HPV infection significantly increased from 2009 to 2015. The four most common high risk human papillomavirus (HR-HPV) genotypes were HPV16 (8.5%), HPV52 (7.9%), HPV58 (6.2%), HPV 53 (3.5%), collectively accounting for 60.5% of all detected HPV infection. Age subgroup analysis showed two peaks for the frequencies of overall and multiple HPV infections, one for the group of women under 25 years old, and the other for the group over 55 years old.ConclusionsHPV infection is becoming serious in Fujian province, which indicates the imperative to implement a HPV vaccination and screening program for this region.
Abstract-We study the problem of information brokerage in sensor networks, where information consumers (sinks, users) search for data acquired by information producers (sources). In-network storage such as geographical hash table (GHT) has been proposed to store data at rendezvous nodes for consumers to retrieve. In this paper, we propose a double rulings scheme which stores data replicas on a curve instead of one or multiple isolated sensors. The consumer travels along another curve which is guaranteed to intersect the producer curve. The double rulings is a natural extension of the flat hashing scheme such as GHTs. It has improved query locality, i.e., consumers close to producers find the data quickly, and structured aggregate queries, i.e., a consumer following a curve is able to retrieve all the data. Further, by the flexibility of retrieval mechanisms we have better routing robustness (as multiple retrieval paths are available) and data robustness against regional node failures. We show by simulation that the double rulings scheme provides reduced communication costs and more balanced traffic load on the sensors.
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