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Sensors, Volume 12, Issue 2 (February 2012), Pages 1130-2350

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Open AccessArticle NIR Monitoring of Ammonia in Anaerobic Digesters Using a Diffuse Reflectance Probe
Sensors 2012, 12(2), 2340-2350; https://doi.org/10.3390/s120202340
Received: 18 January 2012 / Revised: 16 February 2012 / Accepted: 16 February 2012 / Published: 21 February 2012
Cited by 5 | PDF Full-text (393 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The feasibility of using a diffuse reflectance probe attached to a near infrared spectrometer to monitor the total ammonia nitrogen (TAN) content in an anaerobic digester run on cattle manure was investigated; as a previous study has indicated that this probe can be
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The feasibility of using a diffuse reflectance probe attached to a near infrared spectrometer to monitor the total ammonia nitrogen (TAN) content in an anaerobic digester run on cattle manure was investigated; as a previous study has indicated that this probe can be easily attached to an anaerobic digester. Multivariate modelling techniques such as partial least squares regression and interval partial least squares methods were used to build models. Various data pre-treatments were applied to improve the models. The TAN concentrations measured were in the range of 1.5 to 5.5 g/L. An R2 of 0.91 with an RMSEP of 0.32 was obtained implying that the probe could be used for monitoring and screening purposes. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A Bioanalytical Platform for Simultaneous Detection and Quantification of Biological Toxins
Sensors 2012, 12(2), 2324-2339; https://doi.org/10.3390/s120202324
Received: 10 January 2012 / Revised: 9 February 2012 / Accepted: 20 February 2012 / Published: 21 February 2012
Cited by 23 | PDF Full-text (548 KB) | HTML Full-text | XML Full-text
Abstract
Prevalent incidents support the notion that toxins, produced by bacteria, fungi, plants or animals are increasingly responsible for food poisoning or intoxication. Owing to their high toxicity some toxins are also regarded as potential biological warfare agents. Accordingly, control, detection and neutralization of
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Prevalent incidents support the notion that toxins, produced by bacteria, fungi, plants or animals are increasingly responsible for food poisoning or intoxication. Owing to their high toxicity some toxins are also regarded as potential biological warfare agents. Accordingly, control, detection and neutralization of toxic substances are a considerable economic burden to food safety, health care and military biodefense. The present contribution describes a new versatile instrument and related procedures for array-based simultaneous detection of bacterial and plant toxins using a bioanalytical platform which combines the specificity of covalently immobilized capture probes with a dedicated instrumentation and immuno-based microarray analytics. The bioanalytical platform consists of a microstructured polymer slide serving both as support of printed arrays and as incubation chamber. The platform further includes an easy-to-operate instrument for simultaneous slide processing at selectable assay temperature. Cy5 coupled streptavidin is used as unifying fluorescent tracer. Fluorescence image analysis and signal quantitation allow determination of the toxin’s identity and concentration. The system’s performance has been investigated by immunological detection of Botulinum Neurotoxin type A (BoNT/A), Staphylococcal enterotoxin B (SEB), and the plant toxin ricin. Toxins were detectable at levels as low as 0.5–1 ng·mL−1 in buffer or in raw milk. Full article
(This article belongs to the Special Issue Bioassays)
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Open AccessArticle Design and Implementation of an Omni-Directional Underwater Acoustic Micro-Modem Based on a Low-Power Micro-Controller Unit
Sensors 2012, 12(2), 2309-2323; https://doi.org/10.3390/s120202309
Received: 20 December 2011 / Revised: 2 February 2012 / Accepted: 2 February 2012 / Published: 20 February 2012
Cited by 12 | PDF Full-text (939 KB) | HTML Full-text | XML Full-text
Abstract
For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense
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For decades, underwater acoustic communication has been restricted to the point-to-point long distance applications such as deep sea probes and offshore oil fields. For this reason, previous acoustic modems were typically characterized by high data rates and long working ranges at the expense of large size and high power consumption. Recently, as the need for underwater wireless sensor networks (UWSNs) has increased, the research and development of compact and low-power consuming communication devices has become the focus. From the consideration that the requisites of acoustic modems for UWSNs are low power consumption, omni-directional beam pattern, low cost and so on, in this paper, we design and implement an omni-directional underwater acoustic micro-modem satisfying these requirements. In order to execute fast digital domain signal processing and support flexible interfaces with other peripherals, an ARM Cortex-M3 is embedded in the micro-modem. Also, for the realization of small and omni-directional properties, a spherical transducer having a resonant frequency of 70 kHz and a diameter of 34 mm is utilized for the implementation. Physical layer frame format and symbol structure for efficient packet-based underwater communication systems are also investigated. The developed acoustic micro-modem is verified analytically and experimentally in indoor and outdoor environments in terms of functionality and performance. Since the modem satisfies the requirements for use in UWSNs, it could be deployed in a wide range of applications requiring underwater acoustic communication. Full article
(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks)
Open AccessReview Biomarker Discovery by Novel Sensors Based on Nanoproteomics Approaches
Sensors 2012, 12(2), 2284-2308; https://doi.org/10.3390/s120202284
Received: 1 December 2011 / Revised: 20 January 2012 / Accepted: 14 February 2012 / Published: 16 February 2012
Cited by 30 | PDF Full-text (611 KB) | HTML Full-text | XML Full-text
Abstract
During the last years, proteomics has facilitated biomarker discovery by coupling high-throughput techniques with novel nanosensors. In the present review, we focus on the study of label-based and label-free detection systems, as well as nanotechnology approaches, indicating their advantages and applications in biomarker
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During the last years, proteomics has facilitated biomarker discovery by coupling high-throughput techniques with novel nanosensors. In the present review, we focus on the study of label-based and label-free detection systems, as well as nanotechnology approaches, indicating their advantages and applications in biomarker discovery. In addition, several disease biomarkers are shown in order to display the clinical importance of the improvement of sensitivity and selectivity by using nanoproteomics approaches as novel sensors. Full article
(This article belongs to the Special Issue Biomarkers and Nanosensors: New Approaches for Biology and Medicine)
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Open AccessReview Gait Analysis Using Wearable Sensors
Sensors 2012, 12(2), 2255-2283; https://doi.org/10.3390/s120202255
Received: 18 January 2012 / Revised: 10 February 2012 / Accepted: 13 February 2012 / Published: 16 February 2012
Cited by 262 | PDF Full-text (595 KB) | HTML Full-text | XML Full-text
Abstract
Gait analysis using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for multiple health-related applications. As a clinical tool applied in the rehabilitation and diagnosis of medical conditions and sport activities, gait analysis using wearable sensors shows great
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Gait analysis using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for multiple health-related applications. As a clinical tool applied in the rehabilitation and diagnosis of medical conditions and sport activities, gait analysis using wearable sensors shows great prospects. The current paper reviews available wearable sensors and ambulatory gait analysis methods based on the various wearable sensors. After an introduction of the gait phases, the principles and features of wearable sensors used in gait analysis are provided. The gait analysis methods based on wearable sensors is divided into gait kinematics, gait kinetics, and electromyography. Studies on the current methods are reviewed, and applications in sports, rehabilitation, and clinical diagnosis are summarized separately. With the development of sensor technology and the analysis method, gait analysis using wearable sensors is expected to play an increasingly important role in clinical applications. Full article
(This article belongs to the Section Physical Sensors)
Open AccessReview Respiratory Physiology and the Impact of Different Modes of Ventilation on the Photoplethysmographic Waveform
Sensors 2012, 12(2), 2236-2254; https://doi.org/10.3390/s120202236
Received: 13 December 2011 / Revised: 7 February 2012 / Accepted: 8 February 2012 / Published: 16 February 2012
Cited by 7 | PDF Full-text (3524 KB) | HTML Full-text | XML Full-text
Abstract
The photoplethysmographic waveform sits at the core of the most used, and arguably the most important, clinical monitor, the pulse oximeter. Interestingly, the pulse oximeter was discovered while examining an artifact during the development of a noninvasive cardiac output monitor. This article will
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The photoplethysmographic waveform sits at the core of the most used, and arguably the most important, clinical monitor, the pulse oximeter. Interestingly, the pulse oximeter was discovered while examining an artifact during the development of a noninvasive cardiac output monitor. This article will explore the response of the pulse oximeter waveform to various modes of ventilation. Modern digital signal processing is allowing for a re-examination of this ubiquitous signal. The effect of ventilation on the photoplethysmographic waveform has long been thought of as a source of artifact. The primary goal of this article is to improve the understanding of the underlying physiology responsible for the observed phenomena, thereby encouraging the utilization of this understanding to develop new methods of patient monitoring. The reader will be presented with a review of respiratory physiology followed by numerous examples of the impact of ventilation on the photoplethysmographic waveform. Full article
(This article belongs to the Special Issue Optical Sensors in Medicine)
Open AccessArticle Improving Planetary Rover Attitude Estimation via MEMS Sensor Characterization
Sensors 2012, 12(2), 2219-2235; https://doi.org/10.3390/s120202219
Received: 8 December 2011 / Revised: 31 January 2012 / Accepted: 7 February 2012 / Published: 15 February 2012
Cited by 12 | PDF Full-text (2109 KB) | HTML Full-text | XML Full-text
Abstract
Micro Electro-Mechanical Systems (MEMS) are currently being considered in the space sector due to its suitable level of performance for spacecrafts in terms of mechanical robustness with low power consumption, small mass and size, and significant advantage in system design and accommodation. However,
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Micro Electro-Mechanical Systems (MEMS) are currently being considered in the space sector due to its suitable level of performance for spacecrafts in terms of mechanical robustness with low power consumption, small mass and size, and significant advantage in system design and accommodation. However, there is still a lack of understanding regarding the performance and testing of these new sensors, especially in planetary robotics. This paper presents what is missing in the field: a complete methodology regarding the characterization and modeling of MEMS sensors with direct application. A reproducible and complete approach including all the intermediate steps, tools and laboratory equipment is described. The process of sensor error characterization and modeling through to the final integration in the sensor fusion scheme is explained with detail. Although the concept of fusion is relatively easy to comprehend, carefully characterizing and filtering sensor information is not an easy task and is essential for good performance. The strength of the approach has been verified with representative tests of novel high-grade MEMS inertia sensors and exemplary planetary rover platforms with promising results. Full article
(This article belongs to the Special Issue Modeling, Testing and Reliability Issues in MEMS Engineering 2011)
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Open AccessArticle Near Infrared Characterization of Hetero-Core Optical Fiber SPR Sensors Coated with Ta2O5 Film and Their Applications
Sensors 2012, 12(2), 2208-2218; https://doi.org/10.3390/s120202208
Received: 19 January 2012 / Revised: 6 February 2012 / Accepted: 9 February 2012 / Published: 15 February 2012
Cited by 16 | PDF Full-text (648 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes the characteristics of optical fiber sensors with surface plasmon resonance (SPR) at 1,310 nm in which the scattering loss of silica optical fiber is low. SPR operation in the infrared wavelength range is achieved by coating a thin tantalum pentaoxide
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This paper describes the characteristics of optical fiber sensors with surface plasmon resonance (SPR) at 1,310 nm in which the scattering loss of silica optical fiber is low. SPR operation in the infrared wavelength range is achieved by coating a thin tantalum pentaoxide (Ta2O5) film. The novelty of this paper lies in the verification of how the hetero-core scheme could be operated as a commercial base candidate in the sense of easy fabrication, sufficient mechanical strength, and significant sensitivity as a liquid detector under the basis of a low loss transmission network in the near infrared wavelength region. The effect of Ta2O5 layer thickness has been experimentally revealed in the wavelength region extending to 1,800 nm by using the hetero-core structured optical fiber. SPR characterizations have been made in the wavelength region 1,000–1,300 nm, showing the feasible operation at the near infrared wavelength and the possible practical applications. In addition, the technique developed in this work has been interestingly applied to a multi-point water-detection and a water-level gauge in which tandem-connected SPR sensors system using hetero-core structured fibers were incorporated. The detailed performance characteristics are also shown on these applications. Full article
(This article belongs to the Special Issue Optical Fiber Sensors 2012)
Open AccessArticle A Survey on Virtualization of Wireless Sensor Networks
Sensors 2012, 12(2), 2175-2207; https://doi.org/10.3390/s120202175
Received: 21 January 2012 / Revised: 10 February 2012 / Accepted: 14 February 2012 / Published: 15 February 2012
Cited by 51 | PDF Full-text (814 KB) | HTML Full-text | XML Full-text
Abstract
Wireless Sensor Networks (WSNs) are gaining tremendous importance thanks to their broad range of commercial applications such as in smart home automation, health-care and industrial automation. In these applications multi-vendor and heterogeneous sensor nodes are deployed. Due to strict administrative control over the
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Wireless Sensor Networks (WSNs) are gaining tremendous importance thanks to their broad range of commercial applications such as in smart home automation, health-care and industrial automation. In these applications multi-vendor and heterogeneous sensor nodes are deployed. Due to strict administrative control over the specific WSN domains, communication barriers, conflicting goals and the economic interests of different WSN sensor node vendors, it is difficult to introduce a large scale federated WSN. By allowing heterogeneous sensor nodes in WSNs to coexist on a shared physical sensor substrate, virtualization in sensor network may provide flexibility, cost effective solutions, promote diversity, ensure security and increase manageability. This paper surveys the novel approach of using the large scale federated WSN resources in a sensor virtualization environment. Our focus in this paper is to introduce a few design goals, the challenges and opportunities of research in the field of sensor network virtualization as well as to illustrate a current status of research in this field. This paper also presents a wide array of state-of-the art projects related to sensor network virtualization. Full article
(This article belongs to the Section Sensor Networks)
Open AccessArticle A Highly Sensitive CMOS Digital Hall Sensor for Low Magnetic Field Applications
Sensors 2012, 12(2), 2162-2174; https://doi.org/10.3390/s120202162
Received: 22 December 2011 / Revised: 20 January 2012 / Accepted: 21 January 2012 / Published: 15 February 2012
Cited by 10 | PDF Full-text (366 KB) | HTML Full-text | XML Full-text
Abstract
Integrated CMOS Hall sensors have been widely used to measure magnetic fields. However, they are difficult to work with in a low magnetic field environment due to their low sensitivity and large offset. This paper describes a highly sensitive digital Hall sensor fabricated
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Integrated CMOS Hall sensors have been widely used to measure magnetic fields. However, they are difficult to work with in a low magnetic field environment due to their low sensitivity and large offset. This paper describes a highly sensitive digital Hall sensor fabricated in 0.18 μm high voltage CMOS technology for low field applications. The sensor consists of a switched cross-shaped Hall plate and a novel signal conditioner. It effectively eliminates offset and low frequency 1/f noise by applying a dynamic quadrature offset cancellation technique. The measured results show the optimal Hall plate achieves a high current related sensitivity of about 310 V/AT. The whole sensor has a remarkable ability to measure a minimum ±2 mT magnetic field and output a digital Hall signal in a wide temperature range from −40 °C to 120 °C. Full article
(This article belongs to the Section Physical Sensors)
Open AccessCommunication Objective Display and Discrimination of Floral Odors from Amorphophallus titanum, Bloomed on Different Dates and at Different Locations, Using an Electronic Nose
Sensors 2012, 12(2), 2152-2161; https://doi.org/10.3390/s120202152
Received: 1 January 2012 / Revised: 7 February 2012 / Accepted: 8 February 2012 / Published: 15 February 2012
Cited by 9 | PDF Full-text (1319 KB) | HTML Full-text | XML Full-text
Abstract
As olfactory perceptions vary from person to person, it is difficult to describe smells objectively. In contrast, electronic noses also detect smells with their sensors, but in addition describe those using electronic signals. Here we showed a virtual connection method between a human
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As olfactory perceptions vary from person to person, it is difficult to describe smells objectively. In contrast, electronic noses also detect smells with their sensors, but in addition describe those using electronic signals. Here we showed a virtual connection method between a human nose perceptions and electronic nose responses with the smell of standard gases. In this method, Amorphophallus titanum flowers, which emit a strong carrion smell, could objectively be described using an electronic nose, in a way resembling the skill of sommeliers. We could describe the flower smell to be close to that of a mixture of methyl mercaptan and propionic acid, by calculation of the dilution index from electronic resistances. In other words, the smell resembled that of “decayed cabbage, garlic and pungent sour” with possible descriptors. Additionally, we compared the smells of flowers which bloomed on different dates and at different locations and showed the similarity of odor intensities visually, in standard gas categories. We anticipate our assay to be a starting point for a perceptive connection between our noses and electronic noses. Full article
Open AccessReview Waveguide-Mode Sensors as Aptasensors
Sensors 2012, 12(2), 2136-2151; https://doi.org/10.3390/s120202136
Received: 11 January 2012 / Revised: 7 February 2012 / Accepted: 8 February 2012 / Published: 15 February 2012
Cited by 27 | PDF Full-text (960 KB) | HTML Full-text | XML Full-text
Abstract
Aptamers are artificial nucleic acid ligands that can be generated by in vitro selection through partition and amplification. Aptamers can be generated against a wide range of biomolecules through the formation of versatile stem-loop structures. Because aptamers are potential substitutes for antibodies and
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Aptamers are artificial nucleic acid ligands that can be generated by in vitro selection through partition and amplification. Aptamers can be generated against a wide range of biomolecules through the formation of versatile stem-loop structures. Because aptamers are potential substitutes for antibodies and drugs, the development of an aptamer-based sensor (aptasensor) is mandatory for diagnosis. We previously reported that waveguide-mode sensors are useful in the analysis of a wide range of biomolecular interactions, including aptamers. The advantages of the waveguide-mode sensor that we developed include physical and chemical stability and that higher sensitivity can be achieved with ease by perforating the waveguide layer or using colored materials such as dyes or metal nanoparticles as labels. Herein, we provide an overview of the strategies and applications for aptamer-based analyses using waveguide-mode sensors. Full article
(This article belongs to the Special Issue Aptamer-Based Sensors)
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Open AccessArticle Experimental Assessment of Different Receiver Structures for Underwater Acoustic Communications over Multipath Channels
Sensors 2012, 12(2), 2118-2135; https://doi.org/10.3390/s120202118
Received: 20 December 2011 / Revised: 1 February 2012 / Accepted: 3 February 2012 / Published: 14 February 2012
Cited by 5 | PDF Full-text (1803 KB) | HTML Full-text | XML Full-text
Abstract
Underwater communication channels are often complicated, and in particular multipath propagation may cause intersymbol interference (ISI). This paper addresses how to remove ISI, and evaluates the performance of three different receiver structures and their implementations. Using real data collected in a high-frequency (10–14
[...] Read more.
Underwater communication channels are often complicated, and in particular multipath propagation may cause intersymbol interference (ISI). This paper addresses how to remove ISI, and evaluates the performance of three different receiver structures and their implementations. Using real data collected in a high-frequency (10–14 kHz) field experiment, the receiver structures are evaluated by off-line data processing. The three structures are multichannel decision feedback equalizer (DFE), passive time reversal receiver (passive-phase conjugation (PPC) with a single channel DFE), and the joint PPC with multichannel DFE. In sparse channels, dominant arrivals represent the channel information, and the matching pursuit (MP) algorithm which exploits the channel sparseness has been investigated for PPC processing. In the assessment, it is found that: (1) it is advantageous to obtain spatial gain using the adaptive multichannel combining scheme; and (2) the MP algorithm improves the performance of communications using PPC processing. Full article
(This article belongs to the Special Issue Underwater Sensor Nodes and Underwater Sensor Networks)
Open AccessArticle Investigation of the Transient Behavior of a Cantilever Beam Using PVDF Sensors
Sensors 2012, 12(2), 2088-2117; https://doi.org/10.3390/s120202088
Received: 13 December 2011 / Revised: 6 February 2012 / Accepted: 8 February 2012 / Published: 14 February 2012
Cited by 17 | PDF Full-text (4988 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a PVDF film sensor was used to measure the transient responses of a cantilever beam subjected to an impact loading. The measurement capability of a PVDF sensor is affected by the area of the PVDF film sensor and the signal
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In this paper, a PVDF film sensor was used to measure the transient responses of a cantilever beam subjected to an impact loading. The measurement capability of a PVDF sensor is affected by the area of the PVDF film sensor and the signal conditioner (charge amplifier). The influences of these effects on the experimental measurements were investigated. The transient responses for the dynamic strain of the beam were measured simultaneously by the PVDF sensor and a conventional strain gauge. The resonant frequencies of the beam were determined by applying the Fast Fourier Transform on transient results in the time domain of the PVDF sensor and the strain gauge. The experimentally measured resonant frequencies from the PVDF sensor and the strain gauge were compared with those predicted from theoretical and FEM numerical calculations. Based on the comparison of the results measured for these two sensors, the PVDF film sensor proved capable of measuring transient responses for dynamic strain, and its sensitivity is better than that of the strain gauge. Furthermore, almost all the resonant frequencies can be obtained from the results of transient responses for PVDF film. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Architecture and Protocol of a Semantic System Designed for Video Tagging with Sensor Data in Mobile Devices
Sensors 2012, 12(2), 2062-2087; https://doi.org/10.3390/s120202062
Received: 31 January 2012 / Revised: 10 February 2012 / Accepted: 10 February 2012 / Published: 14 February 2012
Cited by 8 | PDF Full-text (420 KB) | HTML Full-text | XML Full-text
Abstract
Current mobile phones come with several sensors and powerful video cameras. These video cameras can be used to capture good quality scenes, which can be complemented with the information gathered by the sensors also embedded in the phones. For example, the surroundings of
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Current mobile phones come with several sensors and powerful video cameras. These video cameras can be used to capture good quality scenes, which can be complemented with the information gathered by the sensors also embedded in the phones. For example, the surroundings of a beach recorded by the camera of the mobile phone, jointly with the temperature of the site can let users know via the Internet if the weather is nice enough to swim. In this paper, we present a system that tags the video frames of the video recorded from mobile phones with the data collected by the embedded sensors. The tagged video is uploaded to a video server, which is placed on the Internet and is accessible by any user. The proposed system uses a semantic approach with the stored information in order to make easy and efficient video searches. Our experimental results show that it is possible to tag video frames in real time and send the tagged video to the server with very low packet delay variations. As far as we know there is not any other application developed as the one presented in this paper. Full article
(This article belongs to the Special Issue Ubiquitous Sensing)
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