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Sensors, Volume 10, Issue 6 (June 2010), Pages 5294-6274

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Open AccessArticle Optical Sensors Based on Whispering Gallery Modes in Fluorescent Microbeads: Response to Specific Interactions
Sensors 2010, 10(6), 6257-6274; https://doi.org/10.3390/s100606257
Received: 8 January 2010 / Revised: 12 March 2010 / Accepted: 9 June 2010 / Published: 22 June 2010
Cited by 27 | PDF Full-text (935 KB) | HTML Full-text | XML Full-text
Abstract
Whispering gallery modes (WGMs) in surface-fixated fluorescent polystyrene microbeads are studied in view of their capability of sensing the formation of biochemical adsorption layers on their outer surface with the well-established biotin-streptavidin specific binding as the model system. Three different methods for analysis
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Whispering gallery modes (WGMs) in surface-fixated fluorescent polystyrene microbeads are studied in view of their capability of sensing the formation of biochemical adsorption layers on their outer surface with the well-established biotin-streptavidin specific binding as the model system. Three different methods for analysis of the observed shifts in the WGM wavelength positions are applied and used to quantify the adsorbed mass densities, which are then compared with the results of a comparative surface plasmon resonance (SPR) study. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle A Nitrite Biosensor Based on Co-immobilization of Nitrite Reductase and Viologen-modified Chitosan on a Glassy Carbon Electrode
Sensors 2010, 10(6), 6241-6256; https://doi.org/10.3390/s100606241
Received: 18 May 2010 / Revised: 8 June 2010 / Accepted: 14 June 2010 / Published: 22 June 2010
Cited by 11 | PDF Full-text (319 KB) | HTML Full-text | XML Full-text
Abstract
An electrochemical nitrite biosensor based on co-immobilization of copper- containing nitrite reductase (Cu-NiR, from Rhodopseudomonas sphaeroides forma sp. denitrificans) and viologen-modified chitosan (CHIT-V) on a glassy carbon electrode (GCE) is presented. Electron transfer (ET) between a conventional GCE and immobilized Cu-NiR was
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An electrochemical nitrite biosensor based on co-immobilization of copper- containing nitrite reductase (Cu-NiR, from Rhodopseudomonas sphaeroides forma sp. denitrificans) and viologen-modified chitosan (CHIT-V) on a glassy carbon electrode (GCE) is presented. Electron transfer (ET) between a conventional GCE and immobilized Cu-NiR was mediated by the co-immobilized CHIT-V. Redox-active viologen was covalently linked to a chitosan backbone, and the thus produced CHIT-V was co-immobilized with Cu-NiR on the GCE surface by drop-coating of hydrophilic polyurethane (HPU). The electrode responded to nitrite with a limit of detection (LOD) of 40 nM (S/N = 3). The sensitivity, linear response range, and response time (t90%) were 14.9 nA/mM, 0.04−11 mM (r2 = 0.999) and 15 s, respectively. The corresponding Lineweaver-Burk plot showed that the apparent Michaelis-Menten constant (KMapp) was 65 mM. Storage stability of the biosensor (retaining 80% of initial activity) was 65 days under ambient air and room temperature storage conditions. Reproducibility of the sensor showed a relative standard deviation (RSD) of 2.8% (n = 5) for detection of 1 mM of nitrite. An interference study showed that anions commonlyfound in water samples such as chlorate, chloride, sulfate and sulfite did not interfere with the nitrite detection. However, nitrate interfered with a relative sensitivity of 64% and this interference effect was due to the intrinsic character of the NiR employed in this study. Full article
(This article belongs to the Section Biosensors)
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Open AccessReview Glucose Signaling-Mediated Coordination of Cell Growth and Cell Cycle in Saccharomyces Cerevisiae
Sensors 2010, 10(6), 6195-6240; https://doi.org/10.3390/s100606195
Received: 7 May 2010 / Revised: 26 May 2010 / Accepted: 27 May 2010 / Published: 21 June 2010
Cited by 54 | PDF Full-text (790 KB) | HTML Full-text | XML Full-text
Abstract
Besides being the favorite carbon and energy source for the budding yeast Sacchromyces cerevisiae, glucose can act as a signaling molecule to regulate multiple aspects of yeast physiology. Yeast cells have evolved several mechanisms for monitoring the level of glucose in their
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Besides being the favorite carbon and energy source for the budding yeast Sacchromyces cerevisiae, glucose can act as a signaling molecule to regulate multiple aspects of yeast physiology. Yeast cells have evolved several mechanisms for monitoring the level of glucose in their habitat and respond quickly to frequent changes in the sugar availability in the environment: the cAMP/PKA pathways (with its two branches comprising Ras and the Gpr1/Gpa2 module), the Rgt2/Snf3-Rgt1 pathway and the main repression pathway involving the kinase Snf1. The cAMP/PKA pathway plays the prominent role in responding to changes in glucose availability and initiating the signaling processes that promote cell growth and division. Snf1 (the yeast homologous to mammalian AMP-activated protein kinase) is primarily required for the adaptation of yeast cell to glucose limitation and for growth on alternative carbon source, but it is also involved in the cellular response to various environmental stresses. The Rgt2/Snf3-Rgt1 pathway regulates the expression of genes required for glucose uptake. Many interconnections exist between the diverse glucose sensing systems, which enables yeast cells to fine tune cell growth, cell cycle and their coordination in response to nutritional changes. Full article
(This article belongs to the Special Issue Glucose Sensors)
Open AccessArticle SirT1—A Sensor for Monitoring Self-Renewal and Aging Process in Retinal Stem Cells
Sensors 2010, 10(6), 6172-6194; https://doi.org/10.3390/s100606172
Received: 8 January 2010 / Revised: 28 February 2010 / Accepted: 3 May 2010 / Published: 21 June 2010
Cited by 16 | PDF Full-text (763 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Retinal stem cells bear potency of proliferation, self-renewal, and differentiation into many retinal cells. Utilizing appropriate sensors one can effectively detect the self-renewal and aging process abilities. Silencing information regulator (SirT1), a member of the sirtuin family, is a NAD-dependent histone deacetylase and
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Retinal stem cells bear potency of proliferation, self-renewal, and differentiation into many retinal cells. Utilizing appropriate sensors one can effectively detect the self-renewal and aging process abilities. Silencing information regulator (SirT1), a member of the sirtuin family, is a NAD-dependent histone deacetylase and an essential mediator for longevity in normal cells by calorie restriction. We firstly investigate the SirT1 mRNA expression in retinal stem cells from rats and 19 human eyes of different ages. Results revealed that SirT1 expression was significantly decreased in in vivo aged eyes, associated with poor self-renewal abilities. Additionally, SirT1 mRNA levels were dose-dependently increased in resveratrol- treated retinal stem cells. The expression of SirT1 on oxidative stress-induced damage was significantly decreased, negatively correlated with the level of intracellular reactive oxygen species production. Treatment with resveratrol could effectively further reduce oxidative stress induced by H2O2 treatment in retinal stem cells. Importantly, the anti-oxidant effects of resveratrol in H2O2-treated retinal stem cells were significantly abolished by knockdown of SirT1 expression (sh-SirT1). SirT1 expression provides a feasible sensor in assessing self-renewal and aging process in retinal stem cells. Resveratrol can prevent reactive oxygen species-induced damages via increased retinal SirT1 expression. Full article
(This article belongs to the Special Issue Delft Workshop 2008-2009—Sensors and Imagers: a VLSI Perspective)
Open AccessReview Review on the Modeling of Electrostatic MEMS
Sensors 2010, 10(6), 6149-6171; https://doi.org/10.3390/s100606149
Received: 9 March 2010 / Revised: 18 May 2010 / Accepted: 24 May 2010 / Published: 21 June 2010
Cited by 69 | PDF Full-text (660 KB) | HTML Full-text | XML Full-text
Abstract
Electrostatic-driven microelectromechanical systems devices, in most cases, consist of couplings of such energy domains as electromechanics, optical electricity, thermoelectricity, and electromagnetism. Their nonlinear working state makes their analysis complex and complicated. This article introduces the physical model of pull-in voltage, dynamic characteristic analysis,
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Electrostatic-driven microelectromechanical systems devices, in most cases, consist of couplings of such energy domains as electromechanics, optical electricity, thermoelectricity, and electromagnetism. Their nonlinear working state makes their analysis complex and complicated. This article introduces the physical model of pull-in voltage, dynamic characteristic analysis, air damping effect, reliability, numerical modeling method, and application of electrostatic-driven MEMS devices. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering - 2009)
Open AccessArticle An Emergency-Adaptive Routing Scheme for Wireless Sensor Networks for Building Fire Hazard Monitoring
Sensors 2010, 10(6), 6128-6148; https://doi.org/10.3390/s100606128
Received: 8 May 2010 / Revised: 4 June 2010 / Accepted: 7 June 2010 / Published: 21 June 2010
Cited by 3 | PDF Full-text (487 KB) | HTML Full-text | XML Full-textRetraction
Abstract
This paper has been retracted on 4 March 2011. The paper is republished with the authorship and acknowledgements fully disclosed as Sensors 2011, 11, 2899-2919; doi:10.3390/s110302899. Available at http://www.mdpi.com/1424-8220/11/3/2899/. Full article
Open AccessArticle Development of an Ion Sensitive Field Effect Transistor Based Urea Biosensor with Solid State Reference Systems
Sensors 2010, 10(6), 6115-6127; https://doi.org/10.3390/s100606115
Received: 14 April 2010 / Revised: 25 May 2010 / Accepted: 1 June 2010 / Published: 21 June 2010
Cited by 6 | PDF Full-text (521 KB) | HTML Full-text | XML Full-text
Abstract
Ion sensitive field-effect transistor (ISFET) based urease biosensors with solid state reference systems for single-ended and two-ended differential readout electronics were investigated. The sensing membranes of the biosensors were fabricated with urease immobilized in a conducting polymer-based matrix. The responses of 12.9~198.1 mV
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Ion sensitive field-effect transistor (ISFET) based urease biosensors with solid state reference systems for single-ended and two-ended differential readout electronics were investigated. The sensing membranes of the biosensors were fabricated with urease immobilized in a conducting polymer-based matrix. The responses of 12.9~198.1 mV for the urea concentrations of 8~240 mg/dL reveal that the activity of the enzyme was not significantly decreased. Biosensors combined with solid state reference systems were fabricated, and the evaluation results demonstrated the feasibility of miniaturization. For the differential system, the optimal transconductance match for biosensor and reference field-effect transistors (REFET) pair was determined through the modification of the membranes of the REFETs and enzyme field-effect transistors (EnFETs). The results show that the transconductance curve of polymer based REFET can match with that of the EnFET by adjusting the photoresist/NafionTM ratio. The match of the transconductance curves for the differential pairs provides a wide dynamic operating measurement range. Accordingly, the miniaturized quasi-reference electrode (QRE)/REFET/EnFET combination with differential arrangement achieved similar urea response curves as those measured by a conventional large sized discrete sensor. Full article
(This article belongs to the Section Biosensors)
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Open AccessArticle Background Subtraction Approach Based on Independent Component Analysis
Sensors 2010, 10(6), 6092-6114; https://doi.org/10.3390/s100606092
Received: 26 April 2010 / Revised: 16 May 2010 / Accepted: 28 May 2010 / Published: 18 June 2010
Cited by 15 | PDF Full-text (7971 KB) | HTML Full-text | XML Full-text
Abstract
In this work, a new approach to background subtraction based on independent component analysis is presented. This approach assumes that background and foreground information are mixed in a given sequence of images. Then, foreground and background components are identified, if their probability density
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In this work, a new approach to background subtraction based on independent component analysis is presented. This approach assumes that background and foreground information are mixed in a given sequence of images. Then, foreground and background components are identified, if their probability density functions are separable from a mixed space. Afterwards, the components estimation process consists in calculating an unmixed matrix. The estimation of an unmixed matrix is based on a fast ICA algorithm, which is estimated as a Newton-Raphson maximization approach. Next, the motion components are represented by the mid-significant eigenvalues from the unmixed matrix. Finally, the results show the approach capabilities to detect efficiently motion in outdoors and indoors scenarios. The results show that the approach is robust to luminance conditions changes at scene. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A Compact Tunable Diode Laser Absorption Spectrometer to Monitor CO2 at 2.7 µm Wavelength in Hypersonic Flows
Sensors 2010, 10(6), 6081-6091; https://doi.org/10.3390/s100606081
Received: 21 May 2010 / Revised: 4 June 2010 / Accepted: 8 June 2010 / Published: 17 June 2010
Cited by 11 | PDF Full-text (969 KB) | HTML Full-text | XML Full-text
Abstract
Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship’s Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based
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Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship’s Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB) diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Arrhythmia ECG Noise Reduction by Ensemble Empirical Mode Decomposition
Sensors 2010, 10(6), 6063-6080; https://doi.org/10.3390/s100606063
Received: 29 April 2010 / Revised: 20 May 2010 / Accepted: 10 June 2010 / Published: 17 June 2010
Cited by 64 | PDF Full-text (298 KB) | HTML Full-text | XML Full-text
Abstract
A novel noise filtering algorithm based on ensemble empirical mode decomposition (EEMD) is proposed to remove artifacts in electrocardiogram (ECG) traces. Three noise patterns with different power—50 Hz, EMG, and base line wander – were embedded into simulated and real ECG signals. Traditional
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A novel noise filtering algorithm based on ensemble empirical mode decomposition (EEMD) is proposed to remove artifacts in electrocardiogram (ECG) traces. Three noise patterns with different power—50 Hz, EMG, and base line wander – were embedded into simulated and real ECG signals. Traditional IIR filter, Wiener filter, empirical mode decomposition (EMD) and EEMD were used to compare filtering performance. Mean square error between clean and filtered ECGs was used as filtering performance indexes. Results showed that high noise reduction is the major advantage of the EEMD based filter, especially on arrhythmia ECGs. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Open AccessArticle A New Collaborative Knowledge-Based Approach for Wireless Sensor Networks
Sensors 2010, 10(6), 6044-6062; https://doi.org/10.3390/s100606044
Received: 28 April 2010 / Revised: 15 May 2010 / Accepted: 5 June 2010 / Published: 17 June 2010
Cited by 7 | PDF Full-text (259 KB) | HTML Full-text | XML Full-text
Abstract
This work presents a new approach for collaboration among sensors in Wireless Sensor Networks. These networks are composed of a large number of sensor nodes with constrained resources: limited computational capability, memory, power sources, etc. Nowadays, there is a growing interest in the
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This work presents a new approach for collaboration among sensors in Wireless Sensor Networks. These networks are composed of a large number of sensor nodes with constrained resources: limited computational capability, memory, power sources, etc. Nowadays, there is a growing interest in the integration of Soft Computing technologies into Wireless Sensor Networks. However, little attention has been paid to integrating Fuzzy Rule-Based Systems into collaborative Wireless Sensor Networks. The objective of this work is to design a collaborative knowledge-based network, in which each sensor executes an adapted Fuzzy Rule-Based System, which presents significant advantages such as: experts can define interpretable knowledge with uncertainty and imprecision, collaborative knowledge can be separated from control or modeling knowledge and the collaborative approach may support neighbor sensor failures and communication errors. As a real-world application of this approach, we demonstrate a collaborative modeling system for pests, in which an alarm about the development of olive tree fly is inferred. The results show that knowledge-based sensors are suitable for a wide range of applications and that the behavior of a knowledge-based sensor may be modified by inferences and knowledge of neighbor sensors in order to obtain a more accurate and reliable output. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessArticle Fast Scene Recognition and Camera Relocalisation for Wide Area Augmented Reality Systems
Sensors 2010, 10(6), 6017-6043; https://doi.org/10.3390/s100606017
Received: 29 April 2010 / Revised: 29 May 2010 / Accepted: 2 June 2010 / Published: 14 June 2010
Cited by 3 | PDF Full-text (3672 KB) | HTML Full-text | XML Full-text
Abstract
This paper focuses on online scene learning and fast camera relocalisation which are two key problems currently limiting the performance of wide area augmented reality systems. Firstly, we propose to use adaptive random trees to deal with the online scene learning problem. The
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This paper focuses on online scene learning and fast camera relocalisation which are two key problems currently limiting the performance of wide area augmented reality systems. Firstly, we propose to use adaptive random trees to deal with the online scene learning problem. The algorithm can provide more accurate recognition rates than traditional methods, especially with large scale workspaces. Secondly, we use the enhanced PROSAC algorithm to obtain a fast camera relocalisation method. Compared with traditional algorithms, our method can significantly reduce the computation complexity, which facilitates to a large degree the process of online camera relocalisation. Finally, we implement our algorithms in a multithreaded manner by using a parallel-computing scheme. Camera tracking, scene mapping, scene learning and relocalisation are separated into four threads by using multi-CPU hardware architecture. While providing real-time tracking performance, the resulting system also possesses the ability to track multiple maps simultaneously. Some experiments have been conducted to demonstrate the validity of our methods. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
Open AccessArticle Wavelet Analysis for Wind Fields Estimation
Sensors 2010, 10(6), 5994-6016; https://doi.org/10.3390/s100605994
Received: 11 May 2010 / Revised: 30 May 2010 / Accepted: 5 June 2010 / Published: 14 June 2010
Cited by 14 | PDF Full-text (5580 KB) | HTML Full-text | XML Full-text
Abstract
Wind field analysis from synthetic aperture radar images allows the estimation of wind direction and speed based on image descriptors. In this paper, we propose a framework to automate wind direction retrieval based on wavelet decomposition associated with spectral processing. We extend existing
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Wind field analysis from synthetic aperture radar images allows the estimation of wind direction and speed based on image descriptors. In this paper, we propose a framework to automate wind direction retrieval based on wavelet decomposition associated with spectral processing. We extend existing undecimated wavelet transform approaches, by including à trous with B3 spline scaling function, in addition to other wavelet bases as Gabor and Mexican-hat. The purpose is to extract more reliable directional information, when wind speed values range from 5 to 10 ms−1. Using C-band empirical models, associated with the estimated directional information, we calculate local wind speed values and compare our results with QuikSCAT scatterometer data. The proposed approach has potential application in the evaluation of oil spills and wind farms. Full article
(This article belongs to the Special Issue Sensor Algorithms)
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Open AccessArticle A Fiber Optic Doppler Sensor and Its Application in Debonding Detection for Composite Structures
Sensors 2010, 10(6), 5975-5993; https://doi.org/10.3390/s100605975
Received: 30 April 2010 / Revised: 20 May 2010 / Accepted: 29 May 2010 / Published: 14 June 2010
Cited by 8 | PDF Full-text (769 KB) | HTML Full-text | XML Full-text
Abstract
Debonding is one of the most important damage forms in fiber-reinforced composite structures. This work was devoted to the debonding damage detection of lap splice joints in carbon fiber reinforced plastic (CFRP) structures, which is based on guided ultrasonic wave signals captured by
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Debonding is one of the most important damage forms in fiber-reinforced composite structures. This work was devoted to the debonding damage detection of lap splice joints in carbon fiber reinforced plastic (CFRP) structures, which is based on guided ultrasonic wave signals captured by using fiber optic Doppler (FOD) sensor with spiral shape. Interferometers based on two types of laser sources, namely the He-Ne laser and the infrared semiconductor laser, are proposed and compared in this study for the purpose of measuring Doppler frequency shift of the FOD sensor. Locations of the FOD sensors are optimized based on mechanical characteristics of lap splice joint. The FOD sensors are subsequently used to detect the guided ultrasonic waves propagating in the CFRP structures. By taking advantage of signal processing approaches, features of the guided wave signals can be revealed. The results demonstrate that debonding in the lap splice joint results in arrival time delay of the first package in the guided wave signals, which can be the characteristic for debonding damage inspection and damage extent estimation. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
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Open AccessArticle Exploring Infrared Sensoring for Real Time Welding Defects Monitoring in GTAW
Sensors 2010, 10(6), 5962-5974; https://doi.org/10.3390/s100605962
Received: 25 April 2010 / Revised: 15 May 2010 / Accepted: 30 May 2010 / Published: 14 June 2010
Cited by 7 | PDF Full-text (918 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an evaluation of an infrared sensor for monitoring the welding pool temperature in a Gas Tungsten Arc Welding (GTAW) process. The purpose of the study is to develop a real time system control. It is known that the arc welding
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This paper presents an evaluation of an infrared sensor for monitoring the welding pool temperature in a Gas Tungsten Arc Welding (GTAW) process. The purpose of the study is to develop a real time system control. It is known that the arc welding pool temperature is related to the weld penetration depth; therefore, by monitoring the temperature, the arc pool temperature and penetration depth are also monitored. Various experiments were performed; in some of them the current was varied and the temperature changes were registered, in others, defects were induced throughout the path of the weld bead for a fixed current. These simulated defects resulted in abrupt changes in the average temperature values, thus providing an indication of the presence of a defect. The data has been registered with an acquisition card. To identify defects in the samples under infrared emissions, the timing series were analyzed through graphics and statistic methods. The selection of this technique demonstrates the potential for infrared emission as a welding monitoring parameter sensor. Full article
(This article belongs to the Section Chemical Sensors)
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