603 research outputs found

    Evanescent incompressible strips as origin of the observed Hall resistance overshoot

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    In this work we provide a systematic explanation to the unusual non-monotonic behavior of the Hall resistance observed at two-dimensional electron systems. We use a semi-analytical model based on the interaction theory of the integer quantized Hall effect to investigate the existence of the anomalous, \emph{i.e} overshoot, Hall resistance RHR_{H}. The observation of the overshoot resistance at low magnetic field edge of the plateaus is elucidated by means of overlapping evanescent incompressible strips, formed due to strong magnetic fields and interactions. Utilizing a self-consistent numerical scheme we also show that, if the magnetic field is decreased the RHR_{H} decreases to its expected value. The effects of the sample width, temperature, disorder strength and magnetic field on the overshoot peaks are investigated in detail. Based on our findings, we predict a controllable procedure to manipulate the maxima of the peaks, which can be tested experimentally. Our model does not depend on specific and intrinsic properties of the material, provided that a single particle gap exists.Comment: A theoretical follow-up paper of arXiv:1007.258

    Pancytopenýa and Sepsýs due to Meropenem: A Case Report

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    Meropenem is one of the most commonly used antibacterial agents with relatively few side effects. Serious adverse reactions reported with meropenem are rare with an incidence of 1 %. Recently we came across two rare adverse effects of meropenem in one patient with acute renal failure. There was pancytopenia and sepsis, respectively. To the best of ourknowledge, a only few cases have been reported in the literature that document an association between meropenem administration and pancytopenia, and about half of these cases were sepsis. With the use of meropenem becoming more widespread, these two rare but fatal complications of meropenem should be borne in mind.Keywords: Meropenem, Pancytopenia, Sepsis, Fatal complication

    Hand gesture based remote control system using infrared sensors and a camera

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    In this paper, a multimodal hand gesture detection and recognition system using differential Pyroelectric Infrared (PIR) sensors and a regular camera is described. Any movement within the viewing range of the differential PIR sensors are first detected by the sensors and then checked if it is due to a hand gesture or not by video analysis. If the movement is due to a hand, one-dimensional continuous-time signals extracted from the PIR sensors are used to classify/recognize the hand movements in real-time. Classification of different hand gestures by using the differential PIR sensors is carried out by a new winner-takeall (WTA) hash based recognition method. Jaccard distance is used to compare the WTA hash codes extracted from 1-D differential infrared sensor signals. It is experimentally shown that the multimodal system achieves higher recognition rates than the system based on only the on/off decisions of the analog circuitry of the PIR sensors. © 2015 IEEE

    Period estimation of an almost periodic signal using persistent homology with application to respiratory rate measurement

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    Time-frequency techniques have difficulties in yielding efficient online algorithms for almost periodic signals. We describe a new topological method to find the period of signals that have an almost periodic waveform. Proposed method is applied to signals received from a pyro-electric infrared sensor array for the online estimation of the respiratory rate (RR) of a person. Timevarying analog signals captured from the sensors exhibit an almost periodic behavior due to repetitive nature of breathing activity. Sensor signals are transformed into two-dimensional point clouds with a technique that allows preserving the period information. Features, which represent the harmonic structures in the sensor signals, are detected by applying persistent homology and the RR is estimated based on the persistence barcode of the first Betti number. Experiments have been carried out to show that our method makes reliable estimates of the RR. © 2017 IEEE

    Purificación de aceite de girasol crudo desgomado mediante estructuras metal-orgánicas seleccionadas como adsorbentes

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    The aims of this study were to investigate the effectiveness of seven metal-organic frameworks (MOFs) as adsorbents for the purification of crude degummed sunflower oil, and to compare their effectiveness with three natural clays. The oil was treated with two different addition levels (0.05% and 0.3%, w/w), and two different treatment times (0.5 h and 3.0 h) under constant temperature (25 °C). The results indicated that all adsorbent treatments improved the oil’s physico-chemical properties. Most importantly, the oil’s free fatty acid, peroxide and p-anisidine values were significantly reduced by Ti-MOF and γ-CD-MOF in comparison with the control sample. The oil showed no contamination by the metals during the MOF treatments. There were no significant changes in the fatty acid or sterol composition of the treated oil, while α-tocopherol contents decreased to some extent. This study proved the possibility of MOF as adsorbents for crude oil purification, and showed the great potential of Ti-MOF and γ-CD-MOF as promising adsorbents.Los objetivos de este estudio fueron investigar la efectividad de siete estructuras metal-orgánicas (MOFs) como adsorbentes para la purificación de aceite de girasol crudo desgomado y comparar su efectividad con tres arcillas naturales. El aceite fué tratado adicionando dos cantidades diferentes (0,05% y 0,3%, p/p) y dos tiempos de de tratamiento (0,5 h y 3,0 h) a temperatura constante (25 °C). Los resultados indicaron que todos los tratamientos con adsorbentes mejoraron las propiedades físico-químicas del aceite. Más importante aún, los valores de acidez libre, peróxidos y p-anisidina se redujeron significativamente con Ti-MOF y γ-CD-MOF en comparación con la muestra de control. Los aceites mostraron no haberse contaminado con los metales durante los tratamientos de MOFs. No hubo cambios significativos en las composiciones de ácidos grasos y esteroles de los aceites tratados, mientras que los contenidos de α-tocoferol disminuyeron a cierto nivel. En consecuencia, este estudio demostró la posibilidad de que los MOFs sean adsorbentes para la purificación de aceites crudos, y demostró el gran potencial de Ti-MOF y γ-CD-MOF como adsorbentes

    Human osteoblasts obtained from distinct periarticular sites demonstrate differences in biological function in vitro.

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    AIMS: Accumulated evidence indicates that local cell origins may ingrain differences in the phenotypic activity of human osteoblasts. We hypothesized that these differences may also exist in osteoblasts harvested from the same bone type at periarticular sites, including those adjacent to the fixation sites for total joint implant components. METHODS: Human osteoblasts were obtained from the acetabulum and femoral neck of seven patients undergoing total hip arthroplasty (THA) and from the femoral and tibial cuts of six patients undergoing total knee arthroplasty (TKA). Osteoblasts were extracted from the usually discarded bone via enzyme digestion, characterized by flow cytometry, and cultured to passage three before measurement of metabolic activity, collagen production, alkaline phosphatase (ALP) expression, and mineralization. RESULTS: Osteoblasts from the acetabulum showed lower proliferation (p = 0.034), cumulative collagen release (p < 0.001), and ALP expression (p = 0.009), and produced less mineral (p = 0.006) than those from the femoral neck. Osteoblasts from the tibia produced significantly less collagen (p = 0.021) and showed lower ALP expression than those from the distal femur. CONCLUSION: We have demonstrated for the first time an anatomical regional variation in the biological behaviours of osteoblasts on either side of the hip and knee joint. The lower osteoblast proliferation, matrix production, and mineralization from the acetabulum compared to those from the proximal femur may be reflected in differences in bone formation and implant fixation at these sites. Cite this article: Bone Joint Res 2021;10(9):611-618

    Wavelet based flickering flame detector using differential PIR sensors

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    Cataloged from PDF version of article.A Pyro-electric Infrared (PIR) sensor based flame detection system is proposed using a Markovian decision algorithm. A differential PIR sensor is only sensitive to sudden temperature variations within its viewing range and it produces a time-varying signal. The wavelet transform of the PIR sensor signal is used for feature extraction from sensor signal and wavelet parameters are fed to a set of Markov models corresponding to the flame flicker process of an uncontrolled fire, ordinary activity of human beings and other objects. The final decision is reached based on the model yielding the highest probability among others. Comparative results show that the system can be used for fire detection in large rooms. (C) 2012 Elsevier Ltd. All rights reserved
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