Surface Acoustic Wave Resonators as Passive Buried Sensors

International audienceAcoustic wave devices are well known passive transducers for probing through a wireless link a physical quantity. Amongst the two main classes of designs - resonators and delay lines - the former have the advantage of providing informations in a narrow band signal and are hence compatible with an interrogation strategy compliant with radiofrequency (RF) emission regulations, while the latter are probed by a short RF pulse with larger instantaneous energy and shorter response time. We here demonstrate the measurement of temperature using the two configurations, and more specifically for sensors buried in soil. While we demonstrate long term stability and ruggedness of packaged resonators, and signal to noise ratio compatible with the envisioned application, the interrogation range in insufficient for most purposes and we focus towards the use of delay lines. Indeed, the interrogation method of the latter is similar to that used by ground penetrating RADAR (GPR) which displays interrogation ranges in the meter to tens of meters in the lower RF range, depending on soil water content, permittivity and conductivity

Chest X-ray and acute bronchiolitis: Are these indications decreasing?

International audienceObjective. A management protocol for infants hospitalized for acute bronchiolitis, established after the study conducted in our unit in 2012, recommends a chest X-ray when the clinical course is unusual or if a differential diagnosis is suspected. The goal of this study was to evaluate professional practices after the introduction of this new management protocol. Study design. Retrospective descriptive study in two pediatric units from October 2013 to March 2015, including infants (0-23 months) hospitalized for their first episode of acute bronchiolitis without any underlying chronic condition. Result. Overall, 599 infants were included (median age, 3.7 months, 54 % boys). Nearly six out of ten (n = 355, 59.3 %) had at least one chest radiograph (38.5 % fewer than in 2012). It was abnormal in 96.3 % of cases, revealing distension and/or bronchial wall thickening (56.7 %), focal opacity (23.5 %), or atelectasis (19.5 %). An X-ray was performed out of the recommendations in 42.5 % of cases. The chest X-ray result led to management changes in 52 infants with prescription of antibiotics for pneumonia (86.5 %) and allowed the diagnosis of heart disease in one case (0.2 %). Management of acute bronchiolitis (X-ray and antibiotics) was statistically different between the two pediatric units. Discussion. This protocol led to a significant decrease in the number of chest X-rays. However, many are still performed out of the recommendations, resulting in an increase of antibiotic use for pneumonia. Conclusion. The decrease in use of chest X-rays in acute bronchiolitis for hospitalized infants was significant but remains insufficient. (C) 2016 Elsevier Masson SAS. All rights reserved