| 1. |
- Nguyen-Tien, Thang, et al.
(författare)
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The Distribution and Composition of Vector Abundance in Hanoi City, Vietnam : Association with Livestock Keeping and Flavivirus Detection
- 2021
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Ingår i: Viruses. - : MDPI. - 1999-4915. ; 13:11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Dengue virus and Japanese encephalitis virus are two common flaviviruses that are spread widely by Aedes and Culex mosquitoes. Livestock keeping is vital for cities; however, it can pose the risk of increasing the mosquito population. Our study explored how livestock keeping in and around a large city is associated with the presence of mosquitoes and the risk of them spreading flaviviruses.Methods: An entomological study was conducted in 6 districts with 233 households with livestock, and 280 households without livestock, in Hanoi city. BG-Sentinel traps and CDC light traps were used to collect mosquitoes close to animal farms and human habitats. Adult mosquitoes were counted, identified to species level, and grouped into 385 pools, which were screened for flaviviruses using a pan-flavivirus qPCR protocol and sequencing.Results: A total of 12,861 adult mosquitoes were collected at the 513 households, with 5 different genera collected, of which the Culex genus was the most abundant. Our study found that there was a positive association between livestock keeping and the size of the mosquito population-most predominantly between pig rearing and Culex species (p < 0.001). One pool of Cx. tritaeniorhynchus, collected in a peri-urban district, was found to be positive for Japanese encephalitis virus.Conclusions: The risk of flavivirus transmission in urban areas of Hanoi city due to the spread of Culex and Aedes mosquitoes could be facilitated by livestock keeping.
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| 2. |
- Tien Viet Dung, Vu, et al.
(författare)
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Antimicrobial susceptibility testing and antibiotic consumption results from 16 hospitals in Viet Nam: The VINARES project 2012-2013
- 2019
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Ingår i: Journal of Global Antimicrobial Resistance. - : ELSEVIER SCI LTD. - 2213-7165 .- 2213-7173. ; 18, s. 269-278
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To establish a hospital-based surveillance network with national coverage for antimicrobial resistance (AMR) and antibiotic consumption in Viet Nam. Methods: A 16-hospital network (Viet Nam Resistance: VINARES) was established and consisted of national and provincial-level hospitals across the country. Antimicrobial susceptibility testing results from routine clinical diagnostic specimens and antibiotic consumption data in Defined Daily Dose per 1000 bed days (DDD/1000 patient-days) were prospectively collected and analysed between October 2012 and September 2013. Results: Data from a total of 24 732 de-duplicated clinical isolates were reported. The most common bacteria were: Escherichia coli (4437 isolates, 18%), Klebsiella spp. (3290 isolates, 13%) and Acinetobacter spp. (2895 isolates, 12%). The hospital average antibiotic consumption was 918 DDD/1000 patient-days. Third-generation cephalosporins were the most frequently used antibiotic class (223 DDD/1000 patient-days, 24%), followed by fluoroquinolones (151 DDD/1000 patient-days, 16%) and second-generation cephalosporins (112 DDD/1000 patient-days, 12%). Proportions of antibiotic resistance were high: 1098/1580 (69%) Staphylococcus aureus isolates were methicillin-resistant (MRSA); 115/344 isolates (33%) and 90/358 (25%) Streptococcus pneumoniae had reduced susceptibility to penicillin and ceftriaxone, respectively. A total of 180/2977 (6%) E. coli and 242/1526 (16%) Klebsiella pneumoniae were resistant to imipenem, respectively; 602/1826 (33%) Pseudomonas aeruginosa were resistant to ceftazidime and 578/1765 (33%) to imipenem. Of Acinetobacter spp. 1495/2138 (70%) were resistant to carbapenems and 2/333 (1%) to colistin. Conclusions: These data are valuable in providing a baseline for AMR among common bacterial pathogens in Vietnamese hospitals and to assess the impact of interventions. (C) 2019 The Authors. Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy.
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| 3. |
- Alves, Dimas I, et al.
(författare)
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A Statistical Analysis for Wavelength-Resolution SAR Image Stacks
- 2020
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Ingår i: IEEE Geoscience and Remote Sensing Letters. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1545-598X .- 1558-0571. ; 17:2, s. 227-231
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents a clutter statistical analysis for stacks of wavelength-resolution synthetic aperture radar (SAR) images. Each image stack consists of SAR images generated by the same sensor, using the same flight track illuminating the same scene but with a time separation between the illuminations. We test three candidate statistical distributions for time changes in the stack, namely, Rician, Rayleigh, and log-normal. The tests results reveal that the Rician distribution is a very good candidate for modeling stack of wavelength-resolution SAR images, where 98.59 & x0025; of the tested samples passed the Anderson-Darling (AD) goodness-of-fit test. Also, it is observed that the presence of changes in the ground scene is related to the tested samples that have failed in the AD test for the Rician distribution hypothesis.
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| 4. |
- Alves, Dimas irion, et al.
(författare)
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Change Detection Method for Wavelength-Resolution SAR Images Based on Bayes’ Theorem : An Iterative Approach
- 2023
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Ingår i: IEEE Access. - Piscataway, NJ : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 11, s. 84734-84743
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an iterative change detection (CD) method based on Bayes’ theorem for very high-frequency (VHF) ultra-wideband (UWB) SAR images considering commonly used clutter-plus-noise statistical models. The proposed detection technique uses the information of the detected changes to iteratively update the data and distribution information, obtaining more accurate clutter-plus-noise statistics resulting in false alarm reduction. The Bivariate Rayleigh and Bivariate Gaussian distributions are investigated as candidates to model the clutter-plus-noise, and the Anderson-Darling goodness-of-fit test is used to investigate three scenarios of interest. Different aspects related to the distributions are discussed, the observed mismatches are analyzed, and the impact of the distribution chosen for the proposed iterative change detection method is analyzed. Finally, the proposed iterative method performance is assessed in terms of the probability of detection and false alarm rate and compared with other competitive solutions. The experimental evaluation uses data from real measurements obtained using the CARABAS II SAR system. Results show that the proposed iterative CD algorithm performs better than the other methods. Author
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| 5. |
- Alves, Dimas, I, et al.
(författare)
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Incoherent Change Detection Methods for Wavelength-Resolution SAR Image Stacks Based on Masking Techniques
- 2020
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Ingår i: 2020 IEEE National Radar Conference - Proceedings. - : IEEE. - 9781728189420
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Konferensbidrag (refereegranskat)abstract
- This paper presents two incoherent change detection methods for wavelength-resolution synthetic aperture radars (SAR) image stacks based on masking techniques. The first technique proposed is the Simple Masking Detection (SMD). This method uses the statistical behavior of pixels-sets in the image stack to create a binary mask, which is used to remove pixels that are not related to changes in a surveillance image from the same interest region. The second technique is the Multiple Concatenated Masking Detection (MCMD), which produces a more selective mask than the SMD by concatenating multiple masks from different image stacks. The MCMD can be used in specific applications where multiple stacks share common patterns of target deployments. Both proposed techniques were evaluated using 24 incoherent SAR images obtained by the CARABAS II system. The experimental results revealed that the proposed detection methods have better performance in terms of probability of detection and false alarm rate when compared with other change detection techniques, especially for high detection probabilities scenarios.
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| 6. |
- Alves, Dimas I., et al.
(författare)
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Neyman-Pearson Criterion-Based Change Detection Methods for Wavelength-Resolution SAR Image Stacks
- 2022
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Ingår i: IEEE Geoscience and Remote Sensing Letters. - : Institute of Electrical and Electronics Engineers Inc.. - 1545-598X .- 1558-0571. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents two new change detection (CD) methods for synthetic aperture radar (SAR) image stacks based on the Neyman-Pearson criterion. The first proposed method uses the data from wavelength-resolution images stack to obtain background statistics, which are used in a hypothesis test to detect changes in a surveillance image. The second method considers a priori information about the targets to obtain the target statistics, which are used together with the previously obtained background statistics, to perform a hypothesis test to detect changes in a surveillance image. A straightforward processing scheme is presented to test the proposed CD methods. To assess the performance of both proposed methods, we considered the coherent all radio band sensing (CARABAS)-II SAR images. In particular, to obtain the temporal background statistics required by the derived methods, we used stacks with six images. The experimental results show that the proposed techniques provide a competitive performance in terms of probability of detection and false alarm rate compared with other CD methods. CCBY
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| 7. |
- Alves, Dimas I, et al.
(författare)
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Statistical Analysis for Wavelength-Resolution SARImage Stacks : New Case Studies
- 2020
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Ingår i: XXXVIII SIMPÓSIO BRASILEIRO DE TELECOMUNICAÇÕES E PROCESSAMENTO DE SINAIS.
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Konferensbidrag (refereegranskat)abstract
- This paper presents new case studies for thestatistical analysis for wavelength resolution SAR image stacks.The statistical analysis considers the Anderson-Darling goodnessof-fit test in a set of pixel samples from the same position obtainedfrom a SAR image stack. The test is applied in wavelengthresolution SAR image stacks. The present work consists of twocase studies based on the use of multiple-pass stacks and TypeI error using the False Discovery Rate controlling procedures.In addition, an application scenario is presented for the studiedscenarios.
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| 8. |
- Alves, Dimas Irion, et al.
(författare)
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Wavelength-Resolution SAR Change Detection Using Bayes' Theorem
- 2020
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Ingår i: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1939-1404 .- 2151-1535. ; 13, s. 5560-5568
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Tidskriftsartikel (refereegranskat)abstract
- This article presents Bayes' theorem for wavelength-resolution synthetic aperture radar (SAR) change detection method development. Different change detection methods can be derived using Bayes' theorem in combination with the target model, clutter-plus-noise model, iterative implementation, and noniterative implementation. As an example of the Bayes' theorem use for wavelength-resolution SAR change detection method development, we propose a simple change detection method with a clutter-plus-noise model and noniterative implementation. In spite of simplicity, the proposed method provides a very competitive performance in terms of probability of detection and false alarm rate. The best result was a probability of detection of $\text{98.7}\%$ versus a false alarm rate of one per square kilometer.
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| 9. |
- Batra, A., et al.
(författare)
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Analysis of Surface Roughness with 3D SAR Imaging at 1.5 THz
- 2023
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Ingår i: 2023 48TH INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER, AND TERAHERTZ WAVES, IRMMW-THZ. - : Institute of Electrical and Electronics Engineers (IEEE). - 9798350336603
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Konferensbidrag (refereegranskat)abstract
- The expansion of the synthetic aperture radar (SAR) to the emerging THz spectrum has enabled a new era of applications in the areas of automobile, security, non-destructive testing, and material characterization. Thanks to the sub-mm wavelength, extraction of material surface properties is possible and of significant interest for the THz SAR applications. The properties define the surface scattering behavior, which is relational to the applied frequency. This study focuses on surface classification. We evaluate the scattering behavior of a rough surface and a smooth surface at 1.5 THz based on a SAR processing sequence that is introduced in this paper. First, we form the 3D SAR images of the metallic objects and then evaluate the surface properties based on the variation in the energy reflected by the object's surface.
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| 10. |
- Batra, Aman, et al.
(författare)
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Experimental analysis of high resolution indoor THz SAR imaging
- 2020
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Ingår i: WSA 2020 - 24th International ITG Workshop on Smart Antennas. - : VDE Verlag GmbH. - 9783800752003
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Konferensbidrag (refereegranskat)abstract
- Synthetic Aperture Radar (SAR) technology is most commonly used in the frequency span of sub-30 GHz which provides the spatial resolution in the range of sub-cm. This technology is being extended to higher frequencies such as millimeter wave and THz region to achieve higher resolution in the range of sub-mm. This expands the SAR applications for material characterization, classification and sub-mm localization. However, the region is suitable for short propagation distance such as an indoor environment. Therefore, to investigate the achieved resolution and quality of the SAR images at THz, an indoor SAR testbed based on vector network analyzer has been setup for the measurements. This paper explains the indoor SAR geometry and describes the associated testbed along with the system parameters. The measurements are performed at a centre frequency of 275 GHz with a bandwidth of 110 GHz. The measurement results are analyzed for the theoretical resolution with the Backprojection Algorithm and the findings are presented in this paper. The sub-mm spatial resolution imaging of two small size metallic objects are performed. © WSA 2020.
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