Dipole Antenna Printed on Paper Substrate for WLAN Applications

International audienceThe design of a dipole antenna printed on a paper substrate is presented in this paper. The antenna which integrates a compact balun is devoted for dual-band 2.4/5 GHz WLAN applications. The antenna is based on a double-side printed multilayer paper substrate and is fed with a coaxial cable for the testing. The simulated results of the whole structure are also presented in detail and compared with the measured performances

Detecting single viruses and nanoparticles using whispering gallery microlasers

Detection and characterization of individual nano-scale particles, virions, and pathogens are of paramount importance to human health, homeland security, diagnostic and environmental monitoring[1]. There is a strong demand for high-resolution, portable, and cost-effective systems to make label-free detection and measurement of individual nanoparticles, molecules, and viruses [2-6]. Here, we report an easily accessible, real-time and label-free detection method with single nanoparticle resolution that surpasses detection limit of existing micro- and nano-photonic devices. This is achieved by using an ultra-narrow linewidth whispering gallery microlaser, whose lasing line undergoes frequency splitting upon the binding of individual nano-objects. We demonstrate detection of polystyrene and gold nanoparticles as small as 15 nm and 10 nm in radius, respectively, and Influenza A virions by monitoring changes in self-heterodyning beat note of the split lasing modes. Experiments are performed in both air and aqueous environment. The built-in self-heterodyne interferometric method achieved in a microlaser provides a self-reference scheme with extraordinary sensitivity [7,8], and paves the way for detection and spectroscopy of nano-scale objects using micro- and nano-lasers.Comment: Main Text: 14 pages, 5 figures, 27 references. Supplement: 26 pages, 12 figures, 26 reference

Gradients and Modulation of K+ Channels Optimize Temporal Accuracy in Networks of Auditory Neurons

Accurate timing of action potentials is required for neurons in auditory brainstem nuclei to encode the frequency and phase of incoming sound stimuli. Many such neurons express “high threshold” Kv3-family channels that are required for firing at high rates (>∼200 Hz). Kv3 channels are expressed in gradients along the medial-lateral tonotopic axis of the nuclei. Numerical simulations of auditory brainstem neurons were used to calculate the input-output relations of ensembles of 1–50 neurons, stimulated at rates between 100–1500 Hz. Individual neurons with different levels of potassium currents differ in their ability to follow specific rates of stimulation but all perform poorly when the stimulus rate is greater than the maximal firing rate of the neurons. The temporal accuracy of the combined synaptic output of an ensemble is, however, enhanced by the presence of gradients in Kv3 channel levels over that measured when neurons express uniform levels of channels. Surprisingly, at high rates of stimulation, temporal accuracy is also enhanced by the occurrence of random spontaneous activity, such as is normally observed in the absence of sound stimulation. For any pattern of stimulation, however, greatest accuracy is observed when, in the presence of spontaneous activity, the levels of potassium conductance in all of the neurons is adjusted to that found in the subset of neurons that respond better than their neighbors. This optimization of response by adjusting the K+ conductance occurs for stimulus patterns containing either single and or multiple frequencies in the phase-locking range. The findings suggest that gradients of channel expression are required for normal auditory processing and that changes in levels of potassium currents across the nuclei, by mechanisms such as protein phosphorylation and rapid changes in channel synthesis, adapt the nuclei to the ongoing auditory environment

Actinic keratosis: a clinical and epidemiological revision

Actinic keratoses are benign intraepithelial skin neoplasms constituted by atypical proliferation of keratinocytes that may evolve to squamous cell carcinoma. They develop in photoexposed skin areas; they are induced mainly by ultraviolet radiation and are considered cutaneous markers of chronic exposure to sunlight. They develop mainly in adults and older, fair skinned individuals, and are the fourth most common cause of dermatologic consultation in Brazil. Damage to the apoptosis pathway in photoexposed epithelium favors cellular proliferation and the permanence of the lesions. In this revision, the authors assemble the main epidemiological data regarding this disease and suggest that strategies to identify risky phenotypes, early diagnosis, adequate treatment, clinical follow-up, stimulus to skin self examination, photoeducation and photoprotection should be promoted with the aim of avoiding the progression to malignancy and also the prevention and the diagnose of concomitant neoplasms also induced by ultraviolet radiation.Queratoses actínicas são neoplasias benignas intraepiteliais formadas por proliferações atípicas de queratinócitos com potencial de transformação em carcinoma espinocelular. Desenvolvem-se em áreas fotoexpostas da pele, são induzidas principalmente pela radiação ultravioleta e constituem marcadores de exposição solar crônica. Acometem indivíduos adultos e idosos, de fototipos claros, representando o quarto diagnóstico dermatológico mais comum no Brasil. Danos nas vias de apoptose do epitélio fotoexposto favorecem a proliferação celular e manutenção das lesões. Nesta revisão os autores reúnem os principais dados epidemiológicos sobre a doença e defendem que estratégias de identificação de fenótipos de risco, diagnóstico precoce, tratamento adequado, seguimento clínico, incentivo ao autoexame da pele, fotoeducação e fotoproteção devem ser promovidas, a fim de evitar a evolução das lesões, e também prevenir e diagnosticar neoplasias concomitantes também induzidas pela radiação solar

Differential symbolic execution

Successful software systems tend to be long lived and evolve over time as requirements change and faults are detected. The number of times a system is updated and re-deployed may be in the hundreds, or even thousands. Re-validation of an updated system, before it is released, is a critical component of the software evolution process. This step ensures that the changes made to the software have their intended effects, and that no unintended behaviors were introduced. Given the size and complexity of modern software systems, re-validation is generally costly and time consuming. Characterizing the differences between software versions can help focus re-validation tasks, potentially reducing the cost and effort necessary to re-deploy the software. Change characterizations are also useful for other software evolution tasks, e.g., assessing the impact of the changes on other parts of the system. Existing change characterization techniques infer differences in program behaviors based on changes to the source code. This approach is imprecise, and therefore, can lead to unnecessary effort and cause delays in deployment. In this dissertation, we present a novel extension and application of symbolic execution techniques that computes a precise behavioral characterization of program changes. This technique, differential symbolic execution (DSE), exploits program version similarities to improve the quality of change information and reduce analysis cost. DSE is not sensitive to formatting and syntactic changes because it is based on a comparison of program semantics. It supports multiple types of equivalence checking, each of which is capable of producing a characterization of behavioral differences and similarities, expressed as sets of program inputs and their associated effects. DSE results can be used to support a wide range of software evolution tasks including program re-validation, impact analysis, and program documentation tasks. Its precise nature has the potential to considerably reduce software maintenance and evolution costs by enabling client analyses to use DSE results to focus on the program execution behaviors that are changed between versions

TECHNICAL NOTE Structural Determination of the Principal Byproduct of the Lithium-Ammonia Reduction Method of Methamphetamine Manufacture

ABSTRACT: One common method of illicit methamphetamine manufacture utilizes an alkali metal, typically lithium, and liquid ammonia to chemically reduce ephedrine or pseudoephedrine to form methamphetamine. This method is often referred to as the lithium-ammonia reduction method or the Birch reduction method. While the hydroxyl group of ephedrine is more reactive than the aromatic ring, excess alkali metal and the presence of a proton source allow the formation of a cyclohexadiene byproduct not found in samples of methamphetamine produced from other manufacturing methods. A sample enriched in this byproduct was generated and characterized using nuclear magnetic resonance (NMR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), infrared (IR) spectrophotometry, and ultraviolet (UV) spectrophotometry. The chemical structure of this byproduct was determined to be 1-(1 ,4 -cyclohexadienyl)-2-methylaminopropane (CMP)

Mutual coupling reduction through choke structures in a Slotted Waveguide Antenna Array

International audienceThis article presents a comprehensive study on reducing mutual coupling in a slotted waveguide antenna array (SWAA), operating in the X band. The objective is to limit such parasitic coupling effects on radiation pattern performances. Optimised choke structures are inserted between adjacent slots sub-arrays in order to control surface currents distribution. Simulation results exhibit a remarkable reduction on isolation between adjacent waveguides. This induces an overall performance improvement in terms of main beam and side lobes control. Furthermore, using field calculator on HFSS™, the efield levels of each slot are extracted. The plus points and drawbacks of the choke structure on the radiation pattern are then explained

NEW CONCEPT OF OIL DISPERSION IN VIEW OF CLEAN UP BY DEGRADATION

ABSTRACT Some misunderstanding has arisen from evidence of deleterious effects of oil dispersion, leading to the conclusion that such a treatment is more dangerous than the pollution itself. In fact, the main objective is to promote the speed of degradation by parcelling of oil, the droplets becoming widespread and bursting at the ocean surface to form films which quickly will disintegrate under microbial actions. With new dispersant formulations, the hydrocarbon pollutants will tend to separate out from sea water so that living organisms would not be injured in the comparatively clean water below. Meanwhile, by its chemical composition, the dispersant will bring nutrients to the medium and, moreover, will remain within the oil phase.</jats:p