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ABSTRACT: Noncontact imaging photoplethysmography (PPG) can provide physiological assessment at various anatomical locations with no discomfort to the patient. However, most previous imaging PPG (iPPG) systems have been limited by a low sample frequency, which restricts their use clinically, for instance, in the assessment of pulse rate variability (PRV). In the present study, plethysmographic signals are remotely captured via an iPPG system at a rate of 200 fps. The physiological parameters (i.e., heart and respiration rate and PRV) derived from the iPPG datasets yield statistically comparable results to those acquired using a contact PPG sensor, the gold standard. More importantly, we present evidence that the negative influence of initial low sample frequency could be compensated via interpolation to improve the time domain resolution. We thereby provide further strong support for the low-cost webcam-based iPPG technique and, importantly, open up a new avenue for effective noncontact assessment of multiple physiological parameters, with potential applications in the evaluation of cardiac autonomic activity and remote sensing of vital physiological signs.
Journal of Biomedical Optics 06/2013; 18(6):61205. · 3.16 Impact Factor
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ABSTRACT: Imaging photoplethysmography (PPG) is able to capture useful physiological data remotely from a wide range of anatomical locations. Recent imaging PPG studies have concentrated on two broad research directions involving either high-performance cameras and or webcam-based systems. However, little has been reported about the difference between these two techniques, particularly in terms of their performance under illumination with ambient light. We explore these two imaging PPG approaches through the simultaneous measurement of the cardiac pulse acquired from the face of 10 male subjects and the spectral characteristics of ambient light. Measurements are made before and after a period of cycling exercise. The physiological pulse waves extracted from both imaging PPG systems using the smoothed pseudo-Wigner-Ville distribution yield functional characteristics comparable to those acquired using gold standard contact PPG sensors. The influence of ambient light intensity on the physiological information is considered, where results reveal an independent relationship between the ambient light intensity and the normalized plethysmographic signals. This provides further support for imaging PPG as a means for practical noncontact physiological assessment with clear applications in several domains, including telemedicine and homecare.
Journal of Biomedical Optics 03/2012; 17(3):037005. · 3.16 Impact Factor
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ABSTRACT: Three flavones were isolated and purified from Nelumbo nucifera Gaertn. by the combination of silica gel chromatography and high-speed counter-current chromatography (HSCCC). The crude extract of N. nucifera was separated by silica gel chromatography and the fraction containing flavones was obtained. Then, the fraction was separated by HSCCC with two phase solvent systems composed of ethyl acetate-ethanol-water-acetic acid (4: 1 : 5:0.025, v/v/v/v). The upper phase was as the stationary phase and the lower phase as the mobile phase. Under the conditions of a flow rate of 2.0 mL/min, while the apparatus rotated at 800 r/min and the detection wavelength was at 254 nm, 6.1 mg of quercetin-3-O-beta-D-glucuronide, 14.8 mg of myricetin-3-O-beta-D-glucopyranoside and 20. 2 mg of astragalin were obtained from 150 mg of the crude sample in one step. The purities determined by high performance liquid chromatography (HPLC) were 97.0%, 95.4% and 96.3%, respectively. The structures of the target compounds were identified by electrospray ionisation mass spectrometry (ESI-MS), 1H-nuclear magnetic resonance (1H-NMR) and 13C-nuclear magnetic resonance (13C-NMR). This method that has practical value not only saves solvent but also is convenient. It is effective in the separation of flavones from N. nucifera, and provides theoretical foundation for the further development and use of N. nucifera resources.
Se pu = Chinese journal of chromatography / Zhongguo hua xue hui 12/2011; 29(12):1244-8.
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ABSTRACT: Orientation control of biological cells under inverted microscopes is important for cell birefringent imaging and micromanipulation. Taking our microrobotic mouse embryo injection research as an example, this paper presents a cell orientation control system operated under inverted microscopes. A compact motorized rotational stage for inverted microscopy was developed for orienting the polar body of mouse embryos away from the injection site to avoid damage of cellular organelles. An in-house developed microdevice was used for immobilizing many cells into a regular pattern. The polar body is tracked by a visual tracking algorithm with a translation-rotation-scaling motion model, providing image position feedback to an image-based visual servo controller that is responsible for online calibration of coordinate transformation during visually servoed orientation of the first embryo. High-speed, automatic cell orientation is then conducted on other embryos in the same batch of immobilized embryos through coordinate transformation and 3-DOF closed-loop position control. Experimental results demonstrate that the cell-orientation system is capable of orienting mouse embryos at a high speed of 720°/s with an accuracy of 0.24°.
IEEE/ASME Transactions on Mechatronics 11/2011; · 2.87 Impact Factor
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ABSTRACT: In light of its capacity for remote physiological assessment over a wide range of anatomical locations, imaging photoplethysmography has become an attractive research area in biomedical and clinical community. Amongst recent iPPG studies, two separate research directions have been revealed, i.e., scientific camera based imaging PPG (iPPG) and webcam based imaging PPG (wPPG). Little is known about the difference between these two techniques. To address this issue, a dual-channel imaging PPG system (iPPG and wPPG) using ambient light as the illumination source has been introduced in this study. The performance of the two imaging PPG techniques was evaluated through the measurement of cardiac pulse acquired from the face of 10 male subjects before and after 10 min of cycling exercise. A time-frequency representation method was used to visualize the time-dependent behaviour of the heart rate. In comparison to the gold standard contact PPG, both imaging PPG techniques exhibit comparable functional characteristics in the context of cardiac pulse assessment. Moreover, the synchronized ambient light intensity recordings in the present study can provide additional information for appraising the performance of the imaging PPG systems. This feasibility study thereby leads to a new route for non-contact monitoring of vital signs, with clear applications in triage and homecare.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
09/2011;
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ABSTRACT: This paper presents a microelectromechanical systems (MEMS) device for simultaneous electrical and mechanical characterization of individual nanowires. The device consists of an electrostatic actuator and two capacitive sensors, capable of acquiring all measurement data (force and displacement) electronically without relying on electron microscopy imaging. This capability avoids the effect of electron beam (e-beam) irradiation during nanomaterial testing. The bulk-microfabricated devices perform electrical characterization at different mechanical strain levels. To integrate individual nanowires to the MEMS device for testing, a nanomanipulation procedure is developed to transfer individual nanowires from their growth substrate to the device inside a scanning electron microscope. Silicon nanowires are characterized using the MEMS device for their piezoresistive as well as mechanical properties. It is also experimentally verified that e-beam irradiation can significantly alter the characterization results and must be avoided during testing.
Journal of Microelectromechanical Systems 09/2011; · 2.10 Impact Factor
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ABSTRACT: This paper is the first report of robotic intracytoplasmic sperm injection (ICSI). ICSI is a clinical procedure performed worldwide in fertility clinics, requiring pick-up of a single sperm and insertion of it into an oocyte (i.e., egg cell). Since its invention 20 years ago, ICSI has been conducted manually by a handful of highly skilled embryologists; however, success rates vary significantly among clinics due to poor reproducibility and inconsistency across operators. We leverage our work in robotic cell injection to realize robotic ICSI and aim ultimately, to standardize how clinical ICSI is performed. This paper presents some of the technical aspects of our robotic ICSI system, including a cell holding device, motion control, and computer vision algorithms. The system performs visual tracking of single sperm, robotic immobilization of sperm, aspiration of sperm with picoliter volume, and insertion of sperm into an oocyte with a high degree of reproducibility. The system requires minimal human involvement (requiring only a few computer mouse clicks), and is human operator skill independent. Using the hamster oocyte-human sperm model in preliminary trials, the robotic system demonstrated a high success rate of 90.0% and survival rate of 90.7% (n = 120).
IEEE Transactions on Biomedical Engineering 08/2011; · 2.28 Impact Factor
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ABSTRACT: Nanomanipulation inside a scanning electron microscope (SEM) has been employed to maneuver and characterize nanomaterials. Despite recent efforts toward automated nanomanipulation, it is still largely conducted manually. In this paper, we demonstrate automated nanomanipulation inside an SEM for a well-structured nanomanipulation task via visual servo control and a vision-based contact-detection method using SEM as a vision sensor. Four-point probe measurement of individual nanowires is achieved automatically by controlling four nanomanipulators with SEM visual feedback. A feedforward controller is incorporated into the control system to improve response time. This technique represents an advance in nanomanipulation inside SEM and can be extended to other nanomanipulation tasks.
IEEE Transactions on Nanotechnology 08/2011; · 2.29 Impact Factor
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ABSTRACT: This paper is the first report of robotic ICSI (intracytoplasmic sperm injection). ICSI is a clinical procedure performed worldwide in fertility clinics, requiring pick-up of a single sperm and insert it into oocyte (i.e., an egg cell). Since its invention 20 years ago, ICSI has been conducted manually by a handful of highly skilled embryologists; however, success rates vary significantly among clinics due to poor reproducibility and inconsistency across operators. We leverage our work in robotic cell injection to realize robotic ICSI and aim ultimately, to standardize how clinical ICSI is performed. This paper presents some of the technical aspects of our robotic ICSI system, including a cell holding device and motion control and computer vision algorithms. The system performs visual tracking of single sperm, robotic immobilization of sperm, aspiration of sperm with pico-liter volume, and insertion of sperm into an oocyte with a high degree of reproducibility. The system requires minimal human involvement (requiring only a few computer mouse clicking), and is human operator skill independent. Using the hamster oocyte-human sperm model in preliminary trials, the robotic system demonstrated a high success rate of 90.0% and survival rate of 90.7% (n=120).
Robotics and Automation (ICRA), 2011 IEEE International Conference on; 06/2011
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ABSTRACT: This paper presents a low-cost automated system that is able to apply a 5-degree-of-freedom (DOF) force on a human fingertip with high precision. It is designed to be used as a calibration platform for the previous proposed fingernail imaging system, and as a haptic system. The system is composed of two Novint Falcon devices linked by two universal joints and a rigid bar to provide 5-DOF motion and force, with feedback from a 6-DOF force sensor. A force controller is designed with an inner position control to meet the calibration goal and requirement. Experiment result and analysis showed that the system was capable of controlling the force with a settling time of less than 0.25 seconds. Two force trajectories are designed for fast and sufficient calibrations. A calibration experiments demonstrated that the system tracked the trajectories with an interval of 0.3 seconds, and step sizes of 0.1 N and 1 N·mm with root-mean-squared errors of 0.02 - 0.04 N for forces and 0.39 N·mm for torque.
Robotics and Automation (ICRA), 2011 IEEE International Conference on; 06/2011
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ABSTRACT: Biological experiments and drug screen require the transfer of individual zebrafish embryos into standard multi-well microplates. Manually pipetting embryos into wells is tedious and time consuming. This paper reports a prototype cooperative robotic system capable of transferring zebrafish embryos in parallel and depositing a single embryo per well in a 96-well microplate. A cell holding device was developed to trap multiple embryos in a regular pattern. The cell holding device and a microplate are positioned and aligned along multiple axes by the system. Embryo release strategies were systematically studied and compared. Experiments demonstrated that out of the 1,056 zebrafish embryos used in experiments (i.e., 44 times parallel transfer into 11 96-well plates), 996 wells were successfully filled with one and only one zebrafish embryo, representing a success rate of 94.3%. Further experiments confirmed that the transferred embryos were able to develop into zebrafish with 100% survival rate.
Robotics and Automation (ICRA), 2011 IEEE International Conference on; 06/2011
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ABSTRACT: This paper presents a nanomanipulation system for operation inside scanning electron microscopes (SEM). The system is small in size, capable of being mounted onto and demounted from an SEM through the specimen exchange chamber without breaking the high vacuum of the SEM. This advance eliminates frequent opening of the high-vacuum chamber, thus, incurs less contamination to the SEM, avoids lengthy pumping, and significantly eases the exchange of end-effectors (e.g., nano probes and grippers). The system consists of two independent 3-DOF Cartesian nanomanipulators based on piezo motors and piezo actuators. High-resolution optical encoders are integrated into the nanomanipulators to provide position feedback for closed-loop control. A look-then-move control system and a contact detection algorithm are implemented for horizontal and vertical nanopositioning. The system design, system characterization details, and system performance are described.
Robotics and Automation (ICRA), 2011 IEEE International Conference on; 06/2011
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ABSTRACT: This Letter provides an overview of microfluidic technologies for single-cell mechanical characterisation. In particular, the most recent literature is discussed to summarise the working principles and development trend of the state-of-the-art microfluidic devices for mechanical characterisation of biological cells in suspension. The techniques are classified into constriction channel, fluid stress, optical stretcher, electro-deformation, electroporation and microfluidic pipette aspiration, according to the mechanism of mechanical stimuli. The principles are explained along with representative examples demonstrating their applications. The research highlighted in this letter has great potential in realising high-throughput single-cell mechanical characterisation.
Micro & Nano Letters 06/2011; · 0.94 Impact Factor
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ABSTRACT: Sperm immobilization is a requisite step in intracytoplasmic sperm injection (ICSI). Conventionally, sperm immobilization is performed manually, which entails long training hours and stringent skills. Manual sperm immobilization also has the limitation of low success rates and poor reproducibility due to human fatigue and skill variations across operators. This paper presents a system for fully automated sperm immobilization to eliminate limitations in manual operation. Integrating computer vision and motion control algorithms, the automated system is able to visually track a sperm and control a micropipette to immobilize the sperm. A robust sperm tail tracking algorithm is developed to locate the optimal position on the sperm tail for sperm immobilization. The system demonstrates: 1) an average sperm tail tracking error of 0.95 μm; 2) a sperm tail visual tracking success rate of 96%; 3) a sperm immobilization success rate of 88.2% (based on 1000 trials); and 4) a speed of 6-7 s per successful immobilization.
IEEE Transactions on Biomedical Engineering 05/2011; · 2.28 Impact Factor
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ABSTRACT: To achieve the best visual quality under the minimum bit rate and the limited buffer size, the rate control allocates appropriate and smooth bits to each frame. This brief proposes an effective bit-allocation strategy for the H.264/Advanced Video Coding rate control. Based on the different characteristics of intraframes and interframes, we introduce the different bit-allocation approaches for them, respectively. A proportional-integer-derivative controller is adopted to minimize the deviation between the target buffer level and the current buffer fullness. To avoid buffer overflow or underflow, a novel setting method for the bit-allocation boundary is presented. Experimental results demonstrate that the proposed bit allocation strategy achieves smooth target bits while better buffer control and visual quality are derived.
Circuits and Systems II: Express Briefs, IEEE Transactions on 04/2011; · 1.41 Impact Factor
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ABSTRACT: We propose a new approach that automatically parallelizes Java programs at runtime. The approach collects on-line trace information during program execution, and dynamically recompiles methods that can be executed in parallel. Wealso describe a cost/benefit model that makes intelligent parallelization decisions, as well as a parallel execution environment to execute parallelized code. We implement these techniques upon Jikes RVM and evaluate our approach by parallelizing sequential benchmarks and comparing the performance to manually parallelized version of those benchmarks. According to the experimental results, our approach has low overheads and achieves competitive speed-ups compared to manually parallelized code.
Interaction between Compilers and Computer Architectures (INTERACT), 2011 15th Workshop on; 03/2011
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ABSTRACT: This paper presents a MEMS device for simultaneous mechanical and electrical characterization of individual nanowires. The device consists of an electrostatic actuator and two capacitive sensors, enabling it to acquire all mechanical measurement data (force and displacement) electronically without relying on electron microscopy imaging. Electrical insulation within the suspended structures of the device enables two-point probe measurements of nanowires. A nanomanipulation procedure is developed to pick up a nanowire from its growth substrate and place it onto the MEMS device inside a scanning electron microscope. Piezoresistivity characterization of silicon nanowires is demonstrated.
Micro Electro Mechanical Systems (MEMS), 2011 IEEE 24th International Conference on; 02/2011
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ABSTRACT: To solve the interoperability is sure between mobile agent and struts 2, Combining the advantages of both, a new Aglet-struts 2 integrated development framework based on MVC is proposed. This framework integrates mobile agent with struts 2 control action, JSP view and java Bean model in together by the aglet action service proxy, and achieves transparent access to database by persistent layer Hiberanate. Using XML technology for data exchange and hierarchical structure for low coupling, Maintainability, extensibility and flexibility of the framework are greatly improved. Finally, through the application of the framework to the remote monitoring system of gas production data the feasibility of the framework is further demonstrated it provides a new solution and means for complex distributed applications.
Computational and Information Sciences (ICCIS), 2010 International Conference on; 01/2011
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ABSTRACT: This research concerns fundamental performance limitations in control of discrete time nonlinear systems. The fundamental limitations are expressed in terms of the average cost of an infinite horizon optimal control problem. The control cost is defined by using a certain Kullback-Leibler divergence metric recently introduced by Todorov. The limitations are obtained via analysis of a linear eigenvalue problem defined only by the open loop dynamics. For a linear time invariant (LTI) system the fundamental limitation is shown to depend upon the unstable eigenvalues, as in the classical Bode formula. For a more general class of nonlinear systems, it is shown that the limitation arise only if the open-loop dynamics are non-ergodic.
Decision and Control (CDC), 2010 49th IEEE Conference on; 01/2011
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ABSTRACT: Two image restoration algorithms based on modified Hop field neural network and variational partial differential equations (PDE) were proposed in our previous work. But the convergence rate of the proposed algorithms was slow. In this paper, we develop a fast update rule based on modified Hop field neural network (MHNN) of continuous state change and two fast image restoration algorithms. Experimental results show that, when compared with the previous algorithms, our proposed algorithms have better performance both in convergence rate and in image restoration quality.
Artificial Intelligence and Computational Intelligence (AICI), 2010 International Conference on; 11/2010
