Energy-efficient, On-demand Reprogramming of Large-scale Sensor Networks

As sensor networks operate over long periods of deployment in difficult to reach places, their requirements may change or new code may need to be uploaded to them. The current state of the art protocols (Deluge and MNP) for network reprogramming perform the code dissemination in a multi-hop manner using a three way handshake whereby meta-data is exchanged prior to code exchange to suppress redundant transmissions. The code image is also pipelined through the network at the granularity of pages. In this paper we propose a protocol called Freshet for optimizing the energy for code upload and speeding up the dissemination if multiple sources of code are available. The energy optimization is achieved by equipping each node with limited non-local topology information, which it uses to determine the time when it can go to sleep since code is not being distributed in its vicinity. The protocol to handle multiple sources provides a loose coupling of nodes to a source and disseminates code in waves each originating at a source, with mechanism to handle collisions when the waves meet. The protocol’s performance with respect to reliability, delay, and energy consumed, is demonstrated through analysis, simulation, and implementation on the Berkeley mote platform

Synergistic effect of imp/ostA and msbA in hydrophobic drug resistance of Helicobacter pylori

<p>Abstract</p> <p>Background</p> <p>Contamination of endoscopy equipment by <it>Helicobacter pylori </it>(<it>H. pylori</it>) frequently occurs after endoscopic examination of <it>H. pylori</it>-infected patients. In the hospital, manual pre-cleaning and soaking in glutaraldehyde is an important process to disinfect endoscopes. However, this might not be sufficient to remove <it>H. pylori </it>completely, and some glutaraldehyde-resistant bacteria might survive and be passed to the next patient undergoing endoscopic examination through unidentified mechanisms. We identified an Imp/OstA protein associated with glutaraldehyde resistance in a clinical strain, NTUH-C1, from our previous study. To better understand and manage the problem of glutaraldehyde resistance, we further investigated its mechanism.</p> <p>Results</p> <p>The minimal inhibitory concentrations (MICs) of glutaraldehyde andexpression of <it>imp/ostA </it>RNA in 11 clinical isolates from the National Taiwan University Hospital were determined. After glutaraldehyde treatment, RNA expression in the strains with the MICs of 4–10 μg/ml was higher than that in strains with the MICs of 1–3 μg/ml. We examined the full-genome expression of strain NTUH-S1 after glutaraldehyde treatment using a microarray and found that 40 genes were upregulated and 31 genes were downregulated. Among the upregulated genes, <it>imp/ostA </it>and <it>msbA</it>, two putative lipopolysaccharide biogenesis genes, were selected for further characterization. The sensitivity to glutaraldehyde or hydrophobic drugs increased in both of <it>imp/ostA </it>and <it>msbA </it>single mutants. The <it>imp/ostA </it>and <it>msbA </it>double mutant was also hypersensitive to these chemicals. The lipopolysaccharide contents decreased in individual <it>imp/ostA </it>and <it>msbA </it>mutants and dramatically reduced in the <it>imp/ostA </it>and <it>msbA </it>double mutant. Outer membrane permeability assay demonstrated that the <it>imp/ostA </it>and <it>msbA </it>double mutation resulted in the increase of outer membrane permeability. Ethidium bromide accumulation assay demonstrated that MsbA was involved in efflux of hydrophobic drugs.</p> <p>Conclusion</p> <p>The expression levels of <it>imp/ostA </it>and <it>msbA </it>were correlated with glutaraldehyde resistance in clinical isolates after glutaraldehyde treatment. Imp/OstA and MsbA play a synergistic role in hydrophobic drugs resistance and lipopolysaccharide biogenesis in <it>H. pylori</it>.</p

Design of Novel S-Shaped Quad-Band Antenna for MedRadio/WMTS/ISM Implantable Biotelemetry Applications

A novel S-shaped quad-band planar inverted-F antenna (PIFA) is proposed for implantable biotelemetry in the Medical Device Radiocommunications Service (MedRadio) band (401–406 MHz), Wireless Medical Telemetry Service (WMTS) band (1427–1432 MHz), and industrial, scientific, and medical (ISM) bands (433-434 MHz and 2.4–2.4835 GHz). The proposed antenna reveals compact dimension of 254 mm3 (10×10×2.45 mm3) and is composed of three substrates and a superstrate, which are constructed from an S-shaped radiator (layer 1) and two twin radiators of spiral structures (layer 2 and layer 3). The optimal antenna characteristics were measured in the ground pork skin, and the measured bandwidths are 150 MHz for the MedRadio and ISM bands (433 MHz), 52 MHz for the WMTS band, and 102 MHz for the ISM band (2.4 GHz), respectively. The characteristics of proposed antenna are enough to support the applications of implantable body area networks (BAN) for biotelemetry and can completely cover main available frequency bands of BAN for biotelemetry below 3 GHz

Fabrication and Photovoltaic Characteristics of Coaxial Silicon Nanowire Solar Cells Prepared by Wet Chemical Etching

Nanostructured solar cells with coaxial p-n junction structures have strong potential to enhance the performances of the silicon-based solar cells. This study demonstrates a radial junction silicon nanowire (RJSNW) solar cell that was fabricated simply and at low cost using wet chemical etching. Experimental results reveal that the reflectance of the silicon nanowires (SNWs) declines as their length increases. The excellent light trapping was mainly associated with high aspect ratio of the SNW arrays. A conversion efficiency of ∼7.1% and an external quantum efficiency of ∼64.6% at 700 nm were demonstrated. Control of etching time and diffusion conditions holds great promise for the development of future RJSNW solar cells. Improving the electrode/RJSNW contact will promote the collection of carries in coaxial core-shell SNW array solar cells

Linguistic Focus Promotes the Ease of Discourse Integration Processes in Reading Comprehension: Evidence From Event-Related Potentials

Psycholinguistic studies of focus processing have yielded varying results regarding how focus affects language processing. We report the results of an event-related potential (ERP) experiment that used question-answer pairs in a discourse to manipulate whether a target word was contextually focused, contrastively focused, contextually defocused, or contextually neutral. We found a negative-going waveform that was sustained in the time-course (250–800 ms after the target word onset) with a maximum over frontal-central scalp sites. As the structure of the discourse made the target word more focused, the negative-going deflection was systematically reduced. We also observed a frontal positive-going waveform that was larger for the focus-marked words relative to the neutral target word in an earlier time window (150–250 ms, P200), which may reflect increased attention allocated to the focused items. We propose that the reduced negative ERPs for the focused words reflects facilitation of meaning integration when focus functions to establish reference in the discourse representation. This can be attributed to extra attention paid to the focus-marked items that in turn promotes the prominence of focus-marked referent and prompts the contextual priming mechanism that facilitates the access of propositionally relevant items in text memory during reading

CT Images of a Malignant-Transformed Ovarian Mature Cystic Teratoma with Rupture: a Case Report

A malignant transformation or a tumor rupture is a rare complication of ovarian mature cystic teratoma (MCT). A tumor rupture in a malignant-transformed MCT has never been reported in the literature. We present the CT images of a 39-year-old woman showing a large, predominantly cystic mass in the lower abdomen, with fat-fluid-level ascites. A contrast-enhanced solid component, with regional discontinuity within the cystic lesion, is also demonstrated. The pathologic diagnosis of the ruptured MCT unveils the malignant transformation (squamous cell carcinoma) and mesenteric carcinomatosis