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Open AccessArticle Induction of miR-3648 Upon ER Stress and Its Regulatory Role in Cell Proliferation
Int. J. Mol. Sci. 2017, 18(7), 1375; doi:10.3390/ijms18071375
Received: 3 May 2017 / Revised: 20 June 2017 / Accepted: 22 June 2017 / Published: 29 June 2017
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Abstract
MicroRNAs (miRNAs) play important roles under multiple cellular conditions including endoplasmic reticulum (ER) stress. We found that miR-3648, a human specific microRNA, was induced under ER stress. Moreover, Adenomatous polyposis coli 2 (APC2), a tumor suppressor and a negative regulator of Wnt signaling,
[...] Read more.
MicroRNAs (miRNAs) play important roles under multiple cellular conditions including endoplasmic reticulum (ER) stress. We found that miR-3648, a human specific microRNA, was induced under ER stress. Moreover, Adenomatous polyposis coli 2 (APC2), a tumor suppressor and a negative regulator of Wnt signaling, was found to be the direct target of miR-3648. Levels of APC2 were downregulated when cells were under ER stress or after overexpressing miR-3648. Inhibition of miR-3648 by antagomir increased APC2 levels and decreased cell proliferation. Conversely, when miR-3648 was overexpressed, APC2 levels were decreased and the cell growth increased. Our data demonstrated that ER stress mediated induction of miR-3648 in human cells, which then downregulated APC2 to increase cell proliferation. Full article
(This article belongs to the collection Regulation by Non-Coding RNAs)
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Open AccessArticle A Spaceborne Synthetic Aperture Radar Partial Fixed-Point Imaging System Using a Field- Programmable Gate Array−Application-Specific Integrated Circuit Hybrid Heterogeneous Parallel Acceleration Technique
Sensors 2017, 17(7), 1493; doi:10.3390/s17071493
Received: 21 April 2017 / Revised: 22 June 2017 / Accepted: 23 June 2017 / Published: 24 June 2017
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Abstract
With the development of satellite load technology and very large scale integrated (VLSI) circuit technology, onboard real-time synthetic aperture radar (SAR) imaging systems have become a solution for allowing rapid response to disasters. A key goal of the onboard SAR imaging system design
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With the development of satellite load technology and very large scale integrated (VLSI) circuit technology, onboard real-time synthetic aperture radar (SAR) imaging systems have become a solution for allowing rapid response to disasters. A key goal of the onboard SAR imaging system design is to achieve high real-time processing performance with severe size, weight, and power consumption constraints. In this paper, we analyse the computational burden of the commonly used chirp scaling (CS) SAR imaging algorithm. To reduce the system hardware cost, we propose a partial fixed-point processing scheme. The fast Fourier transform (FFT), which is the most computation-sensitive operation in the CS algorithm, is processed with fixed-point, while other operations are processed with single precision floating-point. With the proposed fixed-point processing error propagation model, the fixed-point processing word length is determined. The fidelity and accuracy relative to conventional ground-based software processors is verified by evaluating both the point target imaging quality and the actual scene imaging quality. As a proof of concept, a field- programmable gate array−application-specific integrated circuit (FPGA-ASIC) hybrid heterogeneous parallel accelerating architecture is designed and realized. The customized fixed-point FFT is implemented using the 130 nm complementary metal oxide semiconductor (CMOS) technology as a co-processor of the Xilinx xc6vlx760t FPGA. A single processing board requires 12 s and consumes 21 W to focus a 50-km swath width, 5-m resolution stripmap SAR raw data with a granularity of 16,384 × 16,384. Full article
(This article belongs to the Section Remote Sensors)
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Open AccessArticle Experimental Study on the Performance of Water Source Trans-Critical CO2 Heat Pump Water Heater
Energies 2017, 10(6), 810; doi:10.3390/en10060810
Received: 12 March 2017 / Revised: 2 May 2017 / Accepted: 3 June 2017 / Published: 14 June 2017
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Abstract
The effect of the discharge pressure on the performance of the trans-critical CO2 heat pump with a low gas-cooler outlet temperature is experimentally investigated on a test rig of water source heat-pump water heater. The optimal discharge pressure of the trans-critical CO
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The effect of the discharge pressure on the performance of the trans-critical CO2 heat pump with a low gas-cooler outlet temperature is experimentally investigated on a test rig of water source heat-pump water heater. The optimal discharge pressure of the trans-critical CO2 heat pump is investigated under different external operation conditions. When the tap-water temperature is low, the characteristic of the S-shape isotherm at the supercritical region has little effect on the occurrence of the optimal discharge pressure; while the mass flow rate of CO2, the suction pressure and the gas-cooler outlet temperature play a significant role in determining the emergence of the optimal discharge pressure. At the optimal discharge pressure, the COP reaches the peak; however, the corresponding heating capacity is still lower than its maximum, which is reached as the discharge pressure is slightly above the optimal discharge pressure. Reducing the tap-water flowrate or increasing the water-source temperature can increase the optimal discharge pressure. The COP is positively dependent on both the tap-water flowrate and the water-source temperature. In addition, the tap-water flowrate has a negligible influence on the maximum heating capacity while increasing the water-source temperature can greatly enhance the heating capacity. Full article
(This article belongs to the Section Energy Fundamentals and Conversion)
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Open AccessArticle Modeling of Heat Transfer and Oscillating Flow in the Regenerator of a Pulse Tube Cryocooler Operating at 50 Hz
Appl. Sci. 2017, 7(6), 553; doi:10.3390/app7060553
Received: 4 April 2017 / Revised: 19 May 2017 / Accepted: 22 May 2017 / Published: 5 June 2017
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Abstract
The regenerator of the pulse tube refrigerator (PTR) operates with oscillating pressure and mass flow, so a proper description of the heat transfer characteristics of the oscillating flow in the regenerator is crucial. In this paper, a one-dimensional model based on Lagrangian representation
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The regenerator of the pulse tube refrigerator (PTR) operates with oscillating pressure and mass flow, so a proper description of the heat transfer characteristics of the oscillating flow in the regenerator is crucial. In this paper, a one-dimensional model based on Lagrangian representation is developed to simulate the oscillating flow in the regenerator of the PTR. The continuity equation, momentum equation and energy equation are solved iteratively using the SIMPLER algorithm. The Darcy-Brinkman-Forchheimer model is used in the momentum equation, and a thermal non-equilibrium model is implemented in the energy equation. Lagrangian representation is employed to describe the thermodynamics of fluid parcels while the Eulerian representation (control volume method) is adopted for the energy equation of the solid matrix. The boundary conditions are set as the periodic flow of the sine function. The thermodynamic parameters of the gas parcels are obtained, which reveal the critical processes of the heat transfer in the regenerator under oscillating flow. The performance of the regenerator with different geometries is evaluated based on the numerical results. The present study provides insight for better understanding the physical process in the regenerator of the PTR, and the proposed model serves as a useful tool for the design and optimization of the cryogenic regenerator. Full article
(This article belongs to the Special Issue Heat Transfer Processes in Oscillatory Flow Conditions)
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Open AccessArticle An Improved Compressive Sensing and Received Signal Strength-Based Target Localization Algorithm with Unknown Target Population for Wireless Local Area Networks
Sensors 2017, 17(6), 1246; doi:10.3390/s17061246
Received: 10 March 2017 / Revised: 18 May 2017 / Accepted: 22 May 2017 / Published: 30 May 2017
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Abstract
In this paper a two-phase compressive sensing (CS) and received signal strength (RSS)-based target localization approach is proposed to improve position accuracy by dealing with the unknown target population and the effect of grid dimensions on position error. In the coarse localization phase,
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In this paper a two-phase compressive sensing (CS) and received signal strength (RSS)-based target localization approach is proposed to improve position accuracy by dealing with the unknown target population and the effect of grid dimensions on position error. In the coarse localization phase, by formulating target localization as a sparse signal recovery problem, grids with recovery vector components greater than a threshold are chosen as the candidate target grids. In the fine localization phase, by partitioning each candidate grid, the target position in a grid is iteratively refined by using the minimum residual error rule and the least-squares technique. When all the candidate target grids are iteratively partitioned and the measurement matrix is updated, the recovery vector is re-estimated. Threshold-based detection is employed again to determine the target grids and hence the target population. As a consequence, both the target population and the position estimation accuracy can be significantly improved. Simulation results demonstrate that the proposed approach achieves the best accuracy among all the algorithms compared. Full article
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Open AccessArticle Comparison of Two Data Assimilation Methods for Improving MODIS LAI Time Series for Bamboo Forests
Remote Sens. 2017, 9(5), 401; doi:10.3390/rs9050401
Received: 19 January 2017 / Revised: 21 April 2017 / Accepted: 22 April 2017 / Published: 25 April 2017
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Abstract
Bamboo forests, especially the Moso bamboo forest (MBF) and the Lei bamboo forest (LBF), have a strong carbon sequestration capability and play an important role in the global forest carbon cycle. The leaf area index (LAI) is an important structural parameter for simulating
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Bamboo forests, especially the Moso bamboo forest (MBF) and the Lei bamboo forest (LBF), have a strong carbon sequestration capability and play an important role in the global forest carbon cycle. The leaf area index (LAI) is an important structural parameter for simulating the spatiotemporal pattern of the carbon cycle in bamboo forests. However, current LAI products suffer from substantial noise and errors, and data assimilation methods are the most appropriate way to improve the accuracy of LAI data. In this study, two data assimilation methods (the Dual Ensemble Kalman filter (DEnKF) and Particle filter (PF) methods) were applied to improve the quality of MODIS LAI time-series data, which removed noises and smoothed the results using a locally adjusted cubic-spline capping method for the MBF and LBF during 2014–2015. The method with the highest correlation coefficient (r) and lowest root-mean-square error (RMSE) was used to generate highly accurate LAI products of bamboo forests in Zhejiang Province. The results show that the LAI assimilated using two methods saw greatly reduced fluctuations in the MODIS LAI product for both the MBF and the LBF. The LAI assimilated using DEnKF significantly correlated with the observed LAI, with an r value of 0.90 and 0.95, and an RMSE value of 0.42 and 0.42, for the MBF and the LBF, respectively. The PF algorithm achieved a better accuracy than the DEnKF algorithm, with an average increase in r of 8.78% and an average decrease in the RMSE of 33.33%. Therefore, the PF method was applied for LAI assimilation in Zhejiang Province, and the assimilated LAI of bamboo forests achieved a reasonable spatiotemporal pattern in Zhejiang Province. The PF algorithm greatly improves the accuracy of MODIS LAI products and provides a reliable structural parameter for the large-scale simulation of the carbon cycle in bamboo forest ecosystems. Full article
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Open AccessArticle Hotspot Selective Preference of the Chimeric Sequences Formed in Multiple Displacement Amplification
Int. J. Mol. Sci. 2017, 18(3), 492; doi:10.3390/ijms18030492
Received: 22 October 2016 / Revised: 16 February 2017 / Accepted: 20 February 2017 / Published: 24 February 2017
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Abstract
Multiple displacement amplification (MDA) is considered to be a conventional approach to comprehensive amplification from low input DNA. The chimeric reads generated in MDA lead to severe disruption in some studies, including those focusing on heterogeneity, structural variation, and genetic recombination. Meanwhile, the
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Multiple displacement amplification (MDA) is considered to be a conventional approach to comprehensive amplification from low input DNA. The chimeric reads generated in MDA lead to severe disruption in some studies, including those focusing on heterogeneity, structural variation, and genetic recombination. Meanwhile, the generation of by-products gives a new approach to gain insights into the reaction process of φ29 polymerase. Here, we analyzed 36.7 million chimeras and screened 196 billion chimeric hotspots in the human genome, as well as evaluating the hotspot selective preference of chimeras. No significant preference was captured in the distributions of chimeras and hotspots among chromosomes. Hotspots with overlaps for 12–13 nucleotides (nt) were most likely to be selected as templates in chimera generation. Meanwhile, a regularly selective preference was noticed in overlap GC content. The preferences in overlap length and GC content was shown to be pertinent to the sequence denaturation temperature, which pointed out the optimization direction for reducing chimeras. Distance preference between two segments of chimeras was 80–280 nt. The analysis is beneficial for reducing the chimeras in MDA, and the characterization of MDA chimeras is helpful in distinguishing MDA chimeras from chimeric sequences caused by disease. Full article
(This article belongs to the Special Issue Next-Generation Sequencing for Clinical Application)
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Open AccessArticle Initial Results from SQUID Sensor: Analysis and Modeling for the ELF/VLF Atmospheric Noise
Sensors 2017, 17(2), 371; doi:10.3390/s17020371
Received: 4 December 2016 / Revised: 8 February 2017 / Accepted: 10 February 2017 / Published: 14 February 2017
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Abstract
In this paper, the amplitude probability density (APD) of the wideband extremely low frequency (ELF) and very low frequency (VLF) atmospheric noise is studied. The electromagnetic signals from the atmosphere, referred to herein as atmospheric noise, was recorded by a mobile low-temperature superconducting
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In this paper, the amplitude probability density (APD) of the wideband extremely low frequency (ELF) and very low frequency (VLF) atmospheric noise is studied. The electromagnetic signals from the atmosphere, referred to herein as atmospheric noise, was recorded by a mobile low-temperature superconducting quantum interference device (SQUID) receiver under magnetically unshielded conditions. In order to eliminate the adverse effect brought by the geomagnetic activities and powerline, the measured field data was preprocessed to suppress the baseline wandering and harmonics by symmetric wavelet transform and least square methods firstly. Then statistical analysis was performed for the atmospheric noise on different time and frequency scales. Finally, the wideband ELF/VLF atmospheric noise was analyzed and modeled separately. Experimental results show that, Gaussian model is appropriate to depict preprocessed ELF atmospheric noise by a hole puncher operator. While for VLF atmospheric noise, symmetric α-stable (SαS) distribution is more accurate to fit the heavy-tail of the envelope probability density function (pdf). Full article
(This article belongs to the Section Physical Sensors)
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Open AccessReview Recent Developments in Micro-Structured Fiber Optic Sensors
Fibers 2017, 5(1), 3; doi:10.3390/fib5010003
Received: 11 August 2016 / Revised: 12 October 2016 / Accepted: 25 October 2016 / Published: 10 January 2017
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Abstract
Recent developments in fiber-optic sensing have involved booming research in the design and manufacturing of novel micro-structured optical fiber devices. From the conventional tapered fiber architectures to the novel micro-machined devices by advanced laser systems, thousands of micro-structured fiber-optic sensors have been proposed
[...] Read more.
Recent developments in fiber-optic sensing have involved booming research in the design and manufacturing of novel micro-structured optical fiber devices. From the conventional tapered fiber architectures to the novel micro-machined devices by advanced laser systems, thousands of micro-structured fiber-optic sensors have been proposed and fabricated for applications in measuring temperature, strain, refractive index (RI), electric current, displacement, bending, acceleration, force, rotation, acoustic, and magnetic field. The renowned and unparalleled merits of sensors-based micro-machined optical fibers including small footprint, light weight, immunity to electromagnetic interferences, durability to harsh environment, capability of remote control, and flexibility of directly embedding into the structured system have placed them in highly demand for practical use in diverse industries. With the rapid advancement in micro-technology, micro-structured fiber sensors have benefitted from the trends of possessing high performance, versatilities and spatial miniaturization. Here, we comprehensively review the recent progress in the micro-structured fiber-optic sensors with a variety of architectures regarding their fabrications, waveguide properties and sensing applications. Full article
(This article belongs to the Special Issue Optical Fiber Sensors)
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Open AccessArticle Deep Fault Recognizer: An Integrated Model to Denoise and Extract Features for Fault Diagnosis in Rotating Machinery
Appl. Sci. 2017, 7(1), 41; doi:10.3390/app7010041
Received: 17 October 2016 / Revised: 12 December 2016 / Accepted: 27 December 2016 / Published: 30 December 2016
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Abstract
Fault diagnosis in rotating machinery is significant to avoid serious accidents; thus, an accurate and timely diagnosis method is necessary. With the breakthrough in deep learning algorithm, some intelligent methods, such as deep belief network (DBN) and deep convolution neural network (DCNN), have
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Fault diagnosis in rotating machinery is significant to avoid serious accidents; thus, an accurate and timely diagnosis method is necessary. With the breakthrough in deep learning algorithm, some intelligent methods, such as deep belief network (DBN) and deep convolution neural network (DCNN), have been developed with satisfactory performances to conduct machinery fault diagnosis. However, only a few of these methods consider properly dealing with noises that exist in practical situations and the denoising methods are in need of extensive professional experiences. Accordingly, rethinking the fault diagnosis method based on deep architectures is essential. Hence, this study proposes an automatic denoising and feature extraction method that inherently considers spatial and temporal correlations. In this study, an integrated deep fault recognizer model based on the stacked denoising autoencoder (SDAE) is applied to both denoise random noises in the raw signals and represent fault features in fault pattern diagnosis for both bearing rolling fault and gearbox fault, and trained in a greedy layer-wise fashion. Finally, the experimental validation demonstrates that the proposed method has better diagnosis accuracy than DBN, particularly in the existing situation of noises with superiority of approximately 7% in fault diagnosis accuracy. Full article
(This article belongs to the Special Issue Deep Learning Based Machine Fault Diagnosis and Prognosis)
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Open AccessArticle An Integrated GNSS/INS/LiDAR-SLAM Positioning Method for Highly Accurate Forest Stem Mapping
Remote Sens. 2017, 9(1), 3; doi:10.3390/rs9010003
Received: 2 September 2016 / Revised: 23 November 2016 / Accepted: 21 December 2016 / Published: 23 December 2016
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Abstract
Forest mapping, one of the main components of performing a forest inventory, is an important driving force in the development of laser scanning. Mobile laser scanning (MLS), in which laser scanners are installed on moving platforms, has been studied as a convenient measurement
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Forest mapping, one of the main components of performing a forest inventory, is an important driving force in the development of laser scanning. Mobile laser scanning (MLS), in which laser scanners are installed on moving platforms, has been studied as a convenient measurement method for forest mapping in the past several years. Positioning and attitude accuracies are important for forest mapping using MLS systems. Inertial Navigation Systems (INSs) and Global Navigation Satellite Systems (GNSSs) are typical and popular positioning and attitude sensors used in MLS systems. In forest environments, because of the loss of signal due to occlusion and severe multipath effects, the positioning accuracy of GNSS is severely degraded, and even that of GNSS/INS decreases considerably. Light Detection and Ranging (LiDAR)-based Simultaneous Localization and Mapping (SLAM) can achieve higher positioning accuracy in environments containing many features and is commonly implemented in GNSS-denied indoor environments. Forests are different from an indoor environment in that the GNSS signal is available to some extent in a forest. Although the positioning accuracy of GNSS/INS is reduced, estimates of heading angle and velocity can maintain high accurate even with fewer satellites. GNSS/INS and the LiDAR-based SLAM technique can be effectively integrated to form a sustainable, highly accurate positioning and mapping solution for use in forests without additional hardware costs. In this study, information such as heading angles and velocities extracted from a GNSS/INS is utilized to improve the positioning accuracy of the SLAM solution, and two information-aided SLAM methods are proposed. First, a heading angle-aided SLAM (H-aided SLAM) method is proposed that supplies the heading angle from GNSS/INS to SLAM. Field test results show that the horizontal positioning accuracy of an entire trajectory of 800 m is 0.13 m and is significantly improved (by 70%) compared to that of a traditional GNSS/INS; second, a more complex information added SLAM solution that utilizes both heading angle and velocity information simultaneously (HV-aided SLAM) is investigated. Experimental results show that the horizontal positioning accuracy can reach a level of six centimetres with the HV-aided SLAM, which is a significant improvement (by 86%). Thus, a more accurate forest map is obtained by the proposed integrated method. Full article
(This article belongs to the Special Issue Multi-Sensor and Multi-Data Integration in Remote Sensing)
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Open AccessArticle Preparation and Properties of Alkali Activated Metakaolin-Based Geopolymer
Materials 2016, 9(9), 767; doi:10.3390/ma9090767
Received: 14 May 2016 / Revised: 30 August 2016 / Accepted: 2 September 2016 / Published: 8 September 2016
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Abstract
The effective activation and utilization of metakaolin as an alkali activated geopolymer precursor and its use in concrete surface protection is of great interest. In this paper, the formula of alkali activated metakaolin-based geopolymers was studied using an orthogonal experimental design. It was
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The effective activation and utilization of metakaolin as an alkali activated geopolymer precursor and its use in concrete surface protection is of great interest. In this paper, the formula of alkali activated metakaolin-based geopolymers was studied using an orthogonal experimental design. It was found that the optimal geopolymer was prepared with metakaolin, sodium hydroxide, sodium silicate and water, with the molar ratio of SiO2:Al2O3:Na2O:NaOH:H2O being 3.4:1.1:0.5:1.0:11.8. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were adopted to investigate the influence of curing conditions on the mechanical properties and microstructures of the geopolymers. The best curing condition was 60 °C for 168 h, and this alkali activated metakaolin-based geopolymer showed the highest compression strength at 52.26 MPa. In addition, hollow micro-sphere glass beads were mixed with metakaolin particles to improve the thermal insulation properties of the alkali activated metakaolin-based geopolymer. These results suggest that a suitable volume ratio of metakaolin to hollow micro-sphere glass beads in alkali activated metakaolin-based geopolymers was 6:1, which achieved a thermal conductivity of 0.37 W/mK and compressive strength of 50 MPa. By adjusting to a milder curing condition, as-prepared alkali activated metakaolin-based geopolymers could find widespread applications in concrete thermal protection. Full article
(This article belongs to the Special Issue Advances in Geopolymers and Alkali-Activated Materials)
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Open AccessArticle Generalized Robustness of Contextuality
Entropy 2016, 18(9), 297; doi:10.3390/e18090297
Received: 16 May 2016 / Revised: 4 August 2016 / Accepted: 9 August 2016 / Published: 1 September 2016
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Abstract
Motivated by the importance of contextuality and a work on the robustness of the entanglement of mixed quantum states, the robustness of contextuality (RoC) RC(e) of an empirical model e against non-contextual noises was introduced and discussed in Science
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Motivated by the importance of contextuality and a work on the robustness of the entanglement of mixed quantum states, the robustness of contextuality (RoC) R C ( e ) of an empirical model e against non-contextual noises was introduced and discussed in Science China Physics, Mechanics and Astronomy (59(4) and 59(9), 2016). Because noises are not always non-contextual, this paper introduces and discusses the generalized robustness of contextuality (GRoC) R g ( e ) of an empirical model e against general noises. It is proven that R g ( e ) = 0 if and only if e is non-contextual. This means that the quantity R g can be used to distinguish contextual empirical models from non-contextual ones. It is also shown that the function R g is convex on the set of all empirical models and continuous on the set of all no-signaling empirical models. For any two empirical models e and f such that the generalized relative robustness of e with respect to f is finite, a fascinating relationship between the GRoCs of e and f is proven, which reads R g ( e ) R g ( f ) 1 . Lastly, for any n-cycle contextual box e, a relationship between the GRoC R g ( e ) and the extent Δ e of violating the non-contextual inequalities is established. Full article
(This article belongs to the Special Issue Quantum Information 2016)
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Open AccessArticle Shift in HIV/AIDS Epidemic in Southeastern China: A Longitudinal Study from 1987 to 2015
Int. J. Environ. Res. Public Health 2016, 13(8), 794; doi:10.3390/ijerph13080794
Received: 13 June 2016 / Revised: 18 July 2016 / Accepted: 27 July 2016 / Published: 6 August 2016
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Abstract
Objective: The aim of this study was to investigate the shift in the epidemiological features of HIV/AIDS during the last three decades in Fujian Province, southeastern China, so as to provide evidence for the development of novel HIV/AIDS control strategies. Methods: Data pertaining
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Objective: The aim of this study was to investigate the shift in the epidemiological features of HIV/AIDS during the last three decades in Fujian Province, southeastern China, so as to provide evidence for the development of novel HIV/AIDS control strategies. Methods: Data pertaining to the conventional surveillance, sentinel surveillance and epidemiological survey in Fujian Province during the period from 1987 to 2015 were collected. The epidemiological trends were described, and the subtypes of HIV strain were genotyped. In addition, the response to antiretroviral therapy was evaluated, and HIV genotypic resistance was assayed. Results: There was an increasing trend observed in the reported cases of HIV/AIDS in Fujian Province. From 1987 to the end of 2015, a total of 8651 HIV/AIDS cases were reported across the province, with totally 1557 deaths found. Among the total cases, the ratio of male/female cases was 3.7:1, which appeared to be an increasing trend; 77.1% cases were detected in young and middle-aged populations aged 19 to 50 years, however, the new HIV infections recently tended to occur in young people aged 15 to 18 years and in populations aged 50 years and older. Among all infected individuals, 49.3% were married, however, the percentage of unmarried cases increased from 6.67% before 1994 to 40.1% in 2015; 64.8% had junior high school education or lower, however, the proportion of HIV/AIDS cases with junior college education or above gradually increased from 6.5% in 2009 to 21.4% in 2015. The reported HIV/AIDS cases were predominantly found in coastal regions; however, a rapidly increasing trend was seen in the number of HIV/AIDS cases in inland regions, and the geographical variation of the cases gradually reduced. There were multiple routes of HIV transmission found in Fujian Province, and 94.2% infections were sexually transmitted, with a large increase in the percentage of male homosexual transmission. A variety of HIV-1 subtypes were genotyped in the province during the study period, and CRF01-AE and CRF07-BC intersubtype recombinant forms were predominant; however, a declining trend in the proportion of HIV-1 CRF01-AE recombinant virus and a significant rise in the proportion of HIV-1 CRF07-BC recombinant virus were observed. Over 90% HIV inhibition was found in all cases receiving antiretroviral therapy during the period from 2011 to 2015, indicating a low prevalence of HIV drug resistance. Conclusions: An increasing trend is still observed in the HIV/AIDS epidemics in Fujian Province, southeastern China. However, the epidemiological pattern of HIV/AIDS has recently changed in the province, and effective control interventions targeting the shift in the epidemiological features of HIV/AIDS should therefore be implemented to control the spread of the epidemic. Full article
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Open AccessArticle Estimating Roof Solar Energy Potential in the Downtown Area Using a GPU-Accelerated Solar Radiation Model and Airborne LiDAR Data
Remote Sens. 2015, 7(12), 17212-17233; doi:10.3390/rs71215877
Received: 30 October 2015 / Revised: 3 December 2015 / Accepted: 8 December 2015 / Published: 18 December 2015
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Abstract
Solar energy, as a clean and renewable resource is becoming increasingly important in the global context of climate change and energy crisis. Utilization of solar energy in urban areas is of great importance in urban energy planning, environmental conservation, and sustainable development. However,
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Solar energy, as a clean and renewable resource is becoming increasingly important in the global context of climate change and energy crisis. Utilization of solar energy in urban areas is of great importance in urban energy planning, environmental conservation, and sustainable development. However, available spaces for solar panel installation in cities are quite limited except for building roofs. Furthermore, complex urban 3D morphology greatly affects sunlit patterns on building roofs, especially in downtown areas, which makes the determination of roof solar energy potential a challenging task. The object of this study is to estimate the solar radiation on building roofs in an urban area in Shanghai, China, and select suitable spaces for installing solar panels that can effectively utilize solar energy. A Graphic Processing Unit (GPU)-based solar radiation model named SHORTWAVE-C simulating direct and non-direct solar radiation intensity was developed by adding the capability of considering cloud influence into the previous SHORTWAVE model. Airborne Light Detection and Ranging (LiDAR) data was used as the input of the SHORTWAVE-C model and to investigate the morphological characteristics of the study area. The results show that the SHORTWAVE-C model can accurately estimate the solar radiation intensity in a complex urban environment under cloudy conditions, and the GPU acceleration method can reduce the computation time by up to 46%. Two sites with different building densities and rooftop structures were selected to illustrate the influence of urban morphology on the solar radiation and solar illumination duration. Based on the findings, an object-based method was implemented to identify suitable places for rooftop solar panel installation that can fully utilize the solar energy potential. Our study provides useful strategic guidelines for the selection and assessment of roof solar energy potential for urban energy planning. Full article
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Open AccessArticle LiDAR Scan Matching Aided Inertial Navigation System in GNSS-Denied Environments
Sensors 2015, 15(7), 16710-16728; doi:10.3390/s150716710
Received: 13 May 2015 / Revised: 22 June 2015 / Accepted: 3 July 2015 / Published: 10 July 2015
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Abstract
A new scan that matches an aided Inertial Navigation System (INS) with a low-cost LiDAR is proposed as an alternative to GNSS-based navigation systems in GNSS-degraded or -denied environments such as indoor areas, dense forests, or urban canyons. In these areas, INS-based Dead
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A new scan that matches an aided Inertial Navigation System (INS) with a low-cost LiDAR is proposed as an alternative to GNSS-based navigation systems in GNSS-degraded or -denied environments such as indoor areas, dense forests, or urban canyons. In these areas, INS-based Dead Reckoning (DR) and Simultaneous Localization and Mapping (SLAM) technologies are normally used to estimate positions as separate tools. However, there are critical implementation problems with each standalone system. The drift errors of velocity, position, and heading angles in an INS will accumulate over time, and on-line calibration is a must for sustaining positioning accuracy. SLAM performance is poor in featureless environments where the matching errors can significantly increase. Each standalone positioning method cannot offer a sustainable navigation solution with acceptable accuracy. This paper integrates two complementary technologies—INS and LiDAR SLAM—into one navigation frame with a loosely coupled Extended Kalman Filter (EKF) to use the advantages and overcome the drawbacks of each system to establish a stable long-term navigation process. Static and dynamic field tests were carried out with a self-developed Unmanned Ground Vehicle (UGV) platform—NAVIS. The results prove that the proposed approach can provide positioning accuracy at the centimetre level for long-term operations, even in a featureless indoor environment. Full article
(This article belongs to the Special Issue Inertial Sensors and Systems)
Open AccessArticle Fast Fingerprint Database Maintenance for Indoor Positioning Based on UGV SLAM
Sensors 2015, 15(3), 5311-5330; doi:10.3390/s150305311
Received: 13 November 2014 / Revised: 16 February 2015 / Accepted: 17 February 2015 / Published: 4 March 2015
Cited by 11 | Viewed by 1813 | PDF Full-text (4549 KB) | HTML Full-text | XML Full-text
Abstract
Indoor positioning technology has become more and more important in the last two decades. Utilizing Received Signal Strength Indicator (RSSI) fingerprints of Signals of OPportunity (SOP) is a promising alternative navigation solution. However, as the RSSIs vary during operation due to their physical
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Indoor positioning technology has become more and more important in the last two decades. Utilizing Received Signal Strength Indicator (RSSI) fingerprints of Signals of OPportunity (SOP) is a promising alternative navigation solution. However, as the RSSIs vary during operation due to their physical nature and are easily affected by the environmental change, one challenge of the indoor fingerprinting method is maintaining the RSSI fingerprint database in a timely and effective manner. In this paper, a solution for rapidly updating the fingerprint database is presented, based on a self-developed Unmanned Ground Vehicles (UGV) platform NAVIS. Several SOP sensors were installed on NAVIS for collecting indoor fingerprint information, including a digital compass collecting magnetic field intensity, a light sensor collecting light intensity, and a smartphone which collects the access point number and RSSIs of the pre-installed WiFi network. The NAVIS platform generates a map of the indoor environment and collects the SOPs during processing of the mapping, and then the SOP fingerprint database is interpolated and updated in real time. Field tests were carried out to evaluate the effectiveness and efficiency of the proposed method. The results showed that the fingerprint databases can be quickly created and updated with a higher sampling frequency (5Hz) and denser reference points compared with traditional methods, and the indoor map can be generated without prior information. Moreover, environmental changes could also be detected quickly for fingerprint indoor positioning. Full article
(This article belongs to the Special Issue Sensors for Indoor Mapping and Navigation)
Open AccessArticle Could A Deletion in Neuraminidase Stalk Strengthen Human Tropism of the Novel Avian Influenza Virus H7N9 in China, 2013?
Int. J. Environ. Res. Public Health 2015, 12(1), 1020-1028; doi:10.3390/ijerph120101020
Received: 25 September 2014 / Revised: 5 January 2015 / Accepted: 13 January 2015 / Published: 20 January 2015
Cited by 1 | Viewed by 1418 | PDF Full-text (2741 KB) | HTML Full-text | XML Full-text
Abstract
Objective. A novel avian influenza A virus (AIV) H7N9 subtype which emerged in China in 2013 caused worldwide concern. Deletion of amino-acids 69 to 73 in the neuraminidase stalk was its most notable characteristic. This study is aimed to discuss the tropism and
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Objective. A novel avian influenza A virus (AIV) H7N9 subtype which emerged in China in 2013 caused worldwide concern. Deletion of amino-acids 69 to 73 in the neuraminidase stalk was its most notable characteristic. This study is aimed to discuss the tropism and virulence effects of this deletion. Methods: Neuraminidase gene sequences of N9 subtype were collected from NCBI and GISAID. MEGA6.0, Stata12.0, and UCSF Chimera were employed for sequence aligning, significance testing, and protein tertiary structure homology modeling. Results: A total of 736 sequences were obtained; there were 81 human isolates of the novel AIV H7N9, of which 79 had the deletion. Among all the 654 avian origin sequences, only 43 had the deletion (p < 0.001). Tertiary structure displayed that the deletion obviously changed the spatial direction of neuraminidase. Conclusions: The deletion in neuraminidase stalk could have strengthened human tropism of the novel AIV H7N9, as well as its virulence. Full article
Open AccessArticle The Wheat E Subunit of V-Type H+-ATPase Is Involved in the Plant Response to Osmotic Stress
Int. J. Mol. Sci. 2014, 15(9), 16196-16210; doi:10.3390/ijms150916196
Received: 7 July 2014 / Revised: 18 August 2014 / Accepted: 28 August 2014 / Published: 12 September 2014
Cited by 3 | Viewed by 1515 | PDF Full-text (1679 KB) | HTML Full-text | XML Full-text
Abstract
The vacuolar type H+-ATPase (V-type H+-ATPase) plays important roles in establishing an electrochemical H+-gradient across tonoplast, energizing Na+ sequestration into the central vacuole, and enhancing salt stress tolerance in plants. In this paper, a putative E
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The vacuolar type H+-ATPase (V-type H+-ATPase) plays important roles in establishing an electrochemical H+-gradient across tonoplast, energizing Na+ sequestration into the central vacuole, and enhancing salt stress tolerance in plants. In this paper, a putative E subunit of the V-type H+-ATPase gene, W36 was isolated from stress-induced wheat de novo transcriptome sequencing combining with 5'-RACE and RT-PCR methods. The full-length of W36 gene was 1097 bp, which contained a 681 bp open reading frame (ORF) and encoded 227 amino acids. Southern blot analysis indicated that W36 was a single-copy gene. The quantitative real-time PCR (qRT-PCR) analysis revealed that the expression level of W36 could be upregulated by drought, cold, salt, and exogenous ABA treatment. A subcellular localization assay showed that the W36 protein accumulated in the cytoplasm. Isolation of the W36 promoter revealed some cis-acting elements responding to abiotic stresses. Transgenic Arabidopsis plants overexpressing W36 were enhanced salt and mannitol tolerance. These results indicate that W36 is involved in the plant response to osmotic stress. Full article
(This article belongs to the Section Biochemistry, Molecular and Cellular Biology)
Open AccessArticle Identification of Cold-Responsive miRNAs and Their Target Genes in Nitrogen-Fixing Nodules of Soybean
Int. J. Mol. Sci. 2014, 15(8), 13596-13614; doi:10.3390/ijms150813596
Received: 29 May 2014 / Revised: 14 July 2014 / Accepted: 17 July 2014 / Published: 5 August 2014
Cited by 8 | Viewed by 1806 | PDF Full-text (1385 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
As a warm climate species, soybean is highly sensitive to chilling temperatures. Exposure to chilling temperatures causes a significant reduction in the nitrogen fixation rate in soybean plants and subsequent yield loss. However, the molecular basis for the sensitivity of soybean to chilling
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As a warm climate species, soybean is highly sensitive to chilling temperatures. Exposure to chilling temperatures causes a significant reduction in the nitrogen fixation rate in soybean plants and subsequent yield loss. However, the molecular basis for the sensitivity of soybean to chilling is poorly understood. In this study, we identified cold-responsive miRNAs in nitrogen-fixing nodules of soybean. Upon chilling, the expression of gma-miR397a, gma-miR166u and gma-miR171p was greatly upregulated, whereas the expression of gma-miR169c, gma-miR159b, gma-miR319a/b and gma-miR5559 was significantly decreased. The target genes of these miRNAs were predicted and validated using 5' complementary DNA ends (5'-RACE) experiments, and qPCR analysis identified putative genes targeted by the cold-responsive miRNAs in response to chilling temperatures. Taken together, our results reveal that miRNAs may be involved in the protective mechanism against chilling injury in mature nodules of soybean. Full article
Open AccessArticle Characterization of Total Phenolic Constituents from the Stems of Spatholobus suberectus Using LC-DAD-MSn and Their Inhibitory Effect on Human Neutrophil Elastase Activity
Molecules 2013, 18(7), 7549-7556; doi:10.3390/molecules18077549
Received: 3 June 2013 / Revised: 25 June 2013 / Accepted: 26 June 2013 / Published: 27 June 2013
Cited by 10 | Viewed by 2243 | PDF Full-text (205 KB) | HTML Full-text | XML Full-text
Abstract
Spatholobus suberectus Dunn, belonging to the legume family (Fabaceae), has been used as a Traditional Chinese Medicine for the treatment of anemia, menoxenia and rheumatism. A limited number of studies report that various types of flavonoids are the main characteristic constituents of
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Spatholobus suberectus Dunn, belonging to the legume family (Fabaceae), has been used as a Traditional Chinese Medicine for the treatment of anemia, menoxenia and rheumatism. A limited number of studies report that various types of flavonoids are the main characteristic constituents of this herb. We have now found that S. suberectus contains about 2% phenolic components and characterized the major phenolic components as homogeneous B-type procyanidin conjugates using a liquid chromatography with diode-array detection-ESI mass spectrometry (LC-DAD/ESI-MS) method. This is the first report on occurrence of most B-type procyanidins in this herb. Moreover, the total phenolics extract was assayed for inhibitory activity on human neutrophil elastase and its IC50 was found to be 1.33 μg/mL. Full article
(This article belongs to the Section Natural Products)
Open AccessArticle Decomposition Analysis of Energy-Related Industrial CO2 Emissions in China
Energies 2013, 6(5), 2319-2337; doi:10.3390/en6052319
Received: 31 December 2012 / Revised: 7 April 2013 / Accepted: 7 April 2013 / Published: 25 April 2013
Cited by 19 | Viewed by 2276 | PDF Full-text (444 KB) | HTML Full-text | XML Full-text
Abstract
Based on the logarithmic mean Divisia index (LMDI) approach, this paper presents a decomposition analysis of China’s energy-related industrial CO2 emissions from 1985 to 2007, as well as a comparative analysis of differential influences of various factors on six sectors. Via the
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Based on the logarithmic mean Divisia index (LMDI) approach, this paper presents a decomposition analysis of China’s energy-related industrial CO2 emissions from 1985 to 2007, as well as a comparative analysis of differential influences of various factors on six sectors. Via the decomposition, five categories of influencing factors are included: (1) Per capita GDP (PCG) was the largest positive driving factor for industrial CO2 emissions growth for all sectors in China, with the largest cumulative contribution value; Population (P), economic structure (YS) and energy structure (ES) also played a positive driving role, but with weak contributions. As the only negative inhibiting factor, energy intensity (EI) significantly reduced the energy-related CO2 emissions from industrial sectors. Meanwhile, CO2 emissions reduction based on the efficiency of energy use still held a large space. (2) Various influencing factors imposed differential impacts on CO2 emissions of six sectors. Full article
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Open AccessArticle Genetic Diversity Revealed by Single Nucleotide Polymorphism Markers in a Worldwide Germplasm Collection of Durum Wheat
Int. J. Mol. Sci. 2013, 14(4), 7061-7088; doi:10.3390/ijms14047061
Received: 1 February 2013 / Revised: 23 February 2013 / Accepted: 1 March 2013 / Published: 28 March 2013
Cited by 22 | Viewed by 3382 | PDF Full-text (2790 KB) | HTML Full-text | XML Full-text
Abstract
Evaluation of genetic diversity and genetic structure in crops has important implications for plant breeding programs and the conservation of genetic resources. Newly developed single nucleotide polymorphism (SNP) markers are effective in detecting genetic diversity. In the present study, a worldwide durum wheat
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Evaluation of genetic diversity and genetic structure in crops has important implications for plant breeding programs and the conservation of genetic resources. Newly developed single nucleotide polymorphism (SNP) markers are effective in detecting genetic diversity. In the present study, a worldwide durum wheat collection consisting of 150 accessions was used. Genetic diversity and genetic structure were investigated using 946 polymorphic SNP markers covering the whole genome of tetraploid wheat. Genetic structure was greatly impacted by multiple factors, such as environmental conditions, breeding methods reflected by release periods of varieties, and gene flows via human activities. A loss of genetic diversity was observed from landraces and old cultivars to the modern cultivars released during periods of the Early Green Revolution, but an increase in cultivars released during the Post Green Revolution. Furthermore, a comparative analysis of genetic diversity among the 10 mega ecogeographical regions indicated that South America, North America, and Europe possessed the richest genetic variability, while the Middle East showed moderate levels of genetic diversity. Full article
(This article belongs to the Section Biochemistry, Molecular and Cellular Biology)
Open AccessArticle Distributed Temperature and Strain Discrimination with Stimulated Brillouin Scattering and Rayleigh Backscatter in an Optical Fiber
Sensors 2013, 13(2), 1836-1845; doi:10.3390/s130201836
Received: 3 December 2012 / Revised: 21 January 2013 / Accepted: 28 January 2013 / Published: 31 January 2013
Cited by 11 | Viewed by 2948 | PDF Full-text (502 KB) | HTML Full-text | XML Full-text
Abstract
A distributed optical fiber sensor with the capability of simultaneously measuring temperature and strain is proposed using a large effective area non-zero dispersion shifted fiber (LEAF) with sub-meter spatial resolution. The Brillouin frequency shift is measured using Brillouin optical time-domain analysis (BOTDA) with
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A distributed optical fiber sensor with the capability of simultaneously measuring temperature and strain is proposed using a large effective area non-zero dispersion shifted fiber (LEAF) with sub-meter spatial resolution. The Brillouin frequency shift is measured using Brillouin optical time-domain analysis (BOTDA) with differential pulse-width pair technique, while the spectrum shift of the Rayleigh backscatter is measured using optical frequency-domain reflectometry (OFDR). These shifts are the functions of both temperature and strain, and can be used as two independent parameters for the discrimination of temperature and strain. A 92 m measurable range with the spatial resolution of 50 cm is demonstrated experimentally, and accuracies of ±1.2 °C in temperature and ±15 με in strain could be achieved. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Identification and Dynamic Regulation of microRNAs Involved in Salt Stress Responses in Functional Soybean Nodules by High-Throughput Sequencing
Int. J. Mol. Sci. 2013, 14(2), 2717-2738; doi:10.3390/ijms14022717
Received: 10 November 2012 / Revised: 9 January 2013 / Accepted: 15 January 2013 / Published: 28 January 2013
Cited by 25 | Viewed by 4299 | PDF Full-text (759 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Both symbiosis between legumes and rhizobia and nitrogen fixation in functional nodules are dramatically affected by salt stress. Better understanding of the molecular mechanisms that regulate the salt tolerance of functional nodules is essential for genetic improvement of nitrogen fixation efficiency. microRNAs (miRNAs)
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Both symbiosis between legumes and rhizobia and nitrogen fixation in functional nodules are dramatically affected by salt stress. Better understanding of the molecular mechanisms that regulate the salt tolerance of functional nodules is essential for genetic improvement of nitrogen fixation efficiency. microRNAs (miRNAs) have been implicated in stress responses in many plants and in symbiotic nitrogen fixation (SNF) in soybean. However, the dynamic regulation of miRNAs in functioning nodules during salt stress response remains unknown. We performed deep sequencing of miRNAs to understand the miRNA expression profile in normal or salt stressed-soybean mature nodules. We identified 110 known miRNAs belonging to 61 miRNA families and 128 novel miRNAs belonging to 64 miRNA families. Among them, 104 miRNAs were dramatically differentially expressed (>2-fold or detected only in one library) during salt stress. qRT-PCR analysis of eight miRNAs confirmed that these miRNAs were dynamically regulated in response to salt stress in functional soybean nodules. These data significantly increase the number of miRNAs known to be expressed in soybean nodules, and revealed for the first time a dynamic regulation of miRNAs during salt stress in functional nodules. The findings suggest great potential for miRNAs in functional soybean nodules during salt stress. Full article
(This article belongs to the Special Issue Non-Coding RNAs 2012)
Open AccessArticle Human Behavior Cognition Using Smartphone Sensors
Sensors 2013, 13(2), 1402-1424; doi:10.3390/s130201402
Received: 28 November 2012 / Revised: 26 December 2012 / Accepted: 15 January 2013 / Published: 24 January 2013
Cited by 48 | Viewed by 5384 | PDF Full-text (1030 KB) | HTML Full-text | XML Full-text
Abstract
This research focuses on sensing context, modeling human behavior and developing a new architecture for a cognitive phone platform. We combine the latest positioning technologies and phone sensors to capture human movements in natural environments and use the movements to study human behavior.
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This research focuses on sensing context, modeling human behavior and developing a new architecture for a cognitive phone platform. We combine the latest positioning technologies and phone sensors to capture human movements in natural environments and use the movements to study human behavior. Contexts in this research are abstracted as a Context Pyramid which includes six levels: Raw Sensor Data, Physical Parameter, Features/Patterns, Simple Contextual Descriptors, Activity-Level Descriptors, and Rich Context. To achieve implementation of the Context Pyramid on a cognitive phone, three key technologies are utilized: ubiquitous positioning, motion recognition, and human behavior modeling. Preliminary tests indicate that we have successfully achieved the Activity-Level Descriptors level with our LoMoCo (Location-Motion-Context) model. Location accuracy of the proposed solution is up to 1.9 meters in corridor environments and 3.5 meters in open spaces. Test results also indicate that the motion states are recognized with an accuracy rate up to 92.9% using a Least Square-Support Vector Machine (LS-SVM) classifier. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle iParking: An Intelligent Indoor Location-Based Smartphone Parking Service
Sensors 2012, 12(11), 14612-14629; doi:10.3390/s121114612
Received: 3 September 2012 / Revised: 23 October 2012 / Accepted: 24 October 2012 / Published: 31 October 2012
Cited by 24 | Viewed by 5232 | PDF Full-text (3179 KB) | HTML Full-text | XML Full-text
Abstract
Indoor positioning technologies have been widely studied with a number of solutions being proposed, yet substantial applications and services are still fairly primitive. Taking advantage of the emerging concept of the connected car, the popularity of smartphones and mobile Internet, and precise indoor
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Indoor positioning technologies have been widely studied with a number of solutions being proposed, yet substantial applications and services are still fairly primitive. Taking advantage of the emerging concept of the connected car, the popularity of smartphones and mobile Internet, and precise indoor locations, this study presents the development of a novel intelligent parking service called iParking. With the iParking service, multiple parties such as users, parking facilities and service providers are connected through Internet in a distributed architecture. The client software is a light-weight application running on a smartphone, and it works essentially based on a precise indoor positioning solution, which fuses Wireless Local Area Network (WLAN) signals and the measurements of the built-in sensors of the smartphones. The positioning accuracy, availability and reliability of the proposed positioning solution are adequate for facilitating the novel parking service. An iParking prototype has been developed and demonstrated in a real parking environment at a shopping mall. The demonstration showed how the iParking service could improve the parking experience and increase the efficiency of parking facilities. The iParking is a novel service in terms of cost- and energy-efficient solution. Full article
(This article belongs to the Special Issue New Trends towards Automatic Vehicle Control and Perception Systems)
Open AccessReview Recent Progress in Distributed Fiber Optic Sensors
Sensors 2012, 12(7), 8601-8639; doi:10.3390/s120708601
Received: 1 May 2012 / Revised: 15 June 2012 / Accepted: 19 June 2012 / Published: 26 June 2012
Cited by 257 | Viewed by 6217 | PDF Full-text (542 KB) | HTML Full-text | XML Full-text
Abstract
Rayleigh, Brillouin and Raman scatterings in fibers result from the interaction of photons with local material characteristic features like density, temperature and strain. For example an acoustic/mechanical wave generates a dynamic density variation; such a variation may be affected by local temperature, strain,
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Rayleigh, Brillouin and Raman scatterings in fibers result from the interaction of photons with local material characteristic features like density, temperature and strain. For example an acoustic/mechanical wave generates a dynamic density variation; such a variation may be affected by local temperature, strain, vibration and birefringence. By detecting changes in the amplitude, frequency and phase of light scattered along a fiber, one can realize a distributed fiber sensor for measuring localized temperature, strain, vibration and birefringence over lengths ranging from meters to one hundred kilometers. Such a measurement can be made in the time domain or frequency domain to resolve location information. With coherent detection of the scattered light one can observe changes in birefringence and beat length for fibers and devices. The progress on state of the art technology for sensing performance, in terms of spatial resolution and limitations on sensing length is reviewed. These distributed sensors can be used for disaster prevention in the civil structural monitoring of pipelines, bridges, dams and railroads. A sensor with centimeter spatial resolution and high precision measurement of temperature, strain, vibration and birefringence can find applications in aerospace smart structures, material processing, and the characterization of optical materials and devices. Full article
(This article belongs to the Special Issue Optical Fiber Sensors 2012)
Open AccessReview Recent Progress in Brillouin Scattering Based Fiber Sensors
Sensors 2011, 11(4), 4152-4187; doi:10.3390/s110404152
Received: 6 February 2011 / Revised: 25 March 2011 / Accepted: 30 March 2011 / Published: 7 April 2011
Cited by 193 | Viewed by 9452 | PDF Full-text (648 KB) | HTML Full-text | XML Full-text
Abstract
Brillouin scattering in optical fiber describes the interaction of an electro-magnetic field (photon) with a characteristic density variation of the fiber. When the electric field amplitude of an optical beam (so-called pump wave), and another wave is introduced at the downshifted Brillouin frequency
[...] Read more.
Brillouin scattering in optical fiber describes the interaction of an electro-magnetic field (photon) with a characteristic density variation of the fiber. When the electric field amplitude of an optical beam (so-called pump wave), and another wave is introduced at the downshifted Brillouin frequency (namely Stokes wave), the beating between the pump and Stokes waves creates a modified density change via the electrostriction effect, resulting in so-called the stimulated Brillouin scattering. The density variation is associated with a mechanical acoustic wave; and it may be affected by local temperature, strain, and vibration which induce changes in the fiber effective refractive index and sound velocity. Through the measurement of the static or dynamic changes in Brillouin frequency along the fiber one can realize a distributed fiber sensor for local temperature, strain and vibration over tens or hundreds of kilometers. This paper reviews the progress on improving sensing performance parameters like spatial resolution, sensing length limitation and simultaneous temperature and strain measurement. These kinds of sensors can be used in civil structural monitoring of pipelines, bridges, dams, and railroads for disaster prevention. Analogous to the static Bragg grating, one can write a moving Brillouin grating in fibers, with the lifetime of the acoustic wave. The length of the Brillouin grating can be controlled by the writing pulses at any position in fibers. Such gratings can be used to measure changes in birefringence, which is an important parameter in fiber communications. Applications for this kind of sensor can be found in aerospace, material processing and fine structures. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors in Canada)
Open AccessArticle CENet: A Cabinet Environmental Sensing Network
Sensors 2010, 10(2), 1021-1040; doi:10.3390/s100201021
Received: 29 November 2009 / Revised: 24 December 2009 / Accepted: 28 December 2009 / Published: 28 January 2010
Cited by 4 | Viewed by 5958 | PDF Full-text (834 KB) | HTML Full-text | XML Full-text
Abstract
For data center cooling and intelligent substation systems, real time cabinet environmental monitoring is a strong requirement. Monitoring data, such as temperature, humidity, and noise, is important for operators to manage the facilities in cabinets. We here propose a sensing network, called CENet,
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For data center cooling and intelligent substation systems, real time cabinet environmental monitoring is a strong requirement. Monitoring data, such as temperature, humidity, and noise, is important for operators to manage the facilities in cabinets. We here propose a sensing network, called CENet, which is energy efficient and reliable for cabinet environmental monitoring. CENet achieves above 93% reliable data yield and sends fewer beacons compared to periodic beaconing. It does so through a data-aided routing protocol. In addition, based on B-MAC, we propose a scheduling scheme to increase the lifetime of the network by reducing unnecessary message snooping and channel listening, thus it is more energy efficient than B-MAC. The performance of CENet is evaluated by simulations and experiments. Full article
(This article belongs to the Section Chemical Sensors)

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