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1. Instance-Aware Generalized Referring Expression Segmentation

Author

Nguyen, E-Ro, Le, Hieu, Samaras, Dimitris, and Ryoo, Michael

Subjects
Computer Science - Computer Vision and Pattern Recognition, Computer Science - Computation and Language, Computer Science - Machine Learning
Abstract

Recent works on Generalized Referring Expression Segmentation (GRES) struggle with handling complex expressions referring to multiple distinct objects. This is because these methods typically employ an end-to-end foreground-background segmentation and lack a mechanism to explicitly differentiate and associate different object instances to the text query. To this end, we propose InstAlign, a method that incorporates object-level reasoning into the segmentation process. Our model leverages both text and image inputs to extract a set of object-level tokens that capture both the semantic information in the input prompt and the objects within the image. By modeling the text-object alignment via instance-level supervision, each token uniquely represents an object segment in the image, while also aligning with relevant semantic information from the text. Extensive experiments on the gRefCOCO and Ref-ZOM benchmarks demonstrate that our method significantly advances state-of-the-art performance, setting a new standard for precise and flexible GRES., Comment: 12 pages, 7 figures

Published
2024

2. Vision-Aware Text Features in Referring Image Segmentation: From Object Understanding to Context Understanding

Author

Nguyen-Truong, Hai, Nguyen, E-Ro, Vu, Tuan-Anh, Tran, Minh-Triet, Hua, Binh-Son, and Yeung, Sai-Kit

Subjects
Computer Science - Computer Vision and Pattern Recognition, Computer Science - Artificial Intelligence
Abstract

Referring image segmentation is a challenging task that involves generating pixel-wise segmentation masks based on natural language descriptions. The complexity of this task increases with the intricacy of the sentences provided. Existing methods have relied mostly on visual features to generate the segmentation masks while treating text features as supporting components. However, this under-utilization of text understanding limits the model's capability to fully comprehend the given expressions. In this work, we propose a novel framework that specifically emphasizes object and context comprehension inspired by human cognitive processes through Vision-Aware Text Features. Firstly, we introduce a CLIP Prior module to localize the main object of interest and embed the object heatmap into the query initialization process. Secondly, we propose a combination of two components: Contextual Multimodal Decoder and Meaning Consistency Constraint, to further enhance the coherent and consistent interpretation of language cues with the contextual understanding obtained from the image. Our method achieves significant performance improvements on three benchmark datasets RefCOCO, RefCOCO+ and G-Ref. Project page: \url{https://vatex.hkustvgd.com/}., Comment: This paper is accepted in WACV 2025

Published
2024

3. One-dimensional proximity superconductivity in the quantum Hall regime

Author

Barrier, Julien, Kim, Minsoo, Kumar, Roshan Krishna, Xin, Na, Kumaravadivel, P., Hague, Lee, Nguyen, E., Berdyugin, A. I., Moulsdale, Christian, Enaldiev, V. V., Prance, J. R., Koppens, F. H. L., Gorbachev, R. V., Watanabe, K., Taniguchi, T., Glazman, L. I., Grigorieva, I. V., Fal'ko, V. I., and Geim, A. K.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Superconductivity
Abstract

Extensive efforts have been undertaken to combine superconductivity and the quantum Hall effect so that Cooper-pair transport between superconducting electrodes in Josephson junctions is mediated by one-dimensional edge states. This interest has been motivated by prospects of finding new physics, including topologically-protected quasiparticles, but also extends into metrology and device applications. So far it has proven challenging to achieve detectable supercurrents through quantum Hall conductors. Here we show that domain walls in minimally twisted bilayer graphene support exceptionally robust proximity superconductivity in the quantum Hall regime, allowing Josephson junctions to operate in fields close to the upper critical field of superconducting electrodes. The critical current is found to be non-oscillatory and practically unchanging over the entire range of quantizing fields, with its value being limited by the quantum conductance of ballistic, strictly one-dimensional electronic channels residing within the domain walls. The system described is unique in its ability to support Andreev bound states at quantizing fields and offers many interesting directions for further exploration., Comment: 24 pages, 14 figures

Published
2024
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5. Fundamental limits of few-layer NbSe$_2$ microbolometers at terahertz frequencies

Author

Shein, K., Zharkova, E., Kashchenko, M. A., Kolbatova, A. I., Lyubchak, A., Elesin, L., Nguyen, E., Semenov, A., Charaev, I., Schilling, A., Goltsman, G. N., Novoselov, K. S., Gayduchenko, I., and Bandurin, D. A.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The rapid development of infrared spectroscopy, observational astronomy, and scanning near-field microscopy has been enabled by the emergence of sensitive mid- and far-infrared photodetectors. Owing to their exceptional signal-to-noise ratio and fast photoresponse, superconducting hot-electron bolometers (HEBs) have become a critical component in these applications. While superconducting HEBs are traditionally made from sputtered superconducting thin films like Nb or NbN, the potential of layered van der Waals (vdW) superconductors is untapped at THz frequencies. Here, we report the fabrication of superconducting HEBs out of few-layer NbSe$_2$ microwires. By improving the interface between NbSe$_2$ and metal leads connected to a broadband antenna, we overcome the impedance mismatch between this vdW superconductor and the radio frequency (RF) readout circuitry that allowed us to achieve large responsivity THz detection over the range from 0.13 to 2.5 THz with minimum noise equivalent power of 7~pW$\sqrt{Hz}$. Using the heterodyne sub-THz mixing technique, we reveal that NbSe$_2$ superconducting HEBs are relatively fast and feature a characteristic response time in the nanosecond range limited by the slow heat escape to the bath through a SiO$_2$ layer, on which they are assembled, in agreement with energy relaxation model. Our work expands the family of materials for superconducting HEBs technology, reveals NbSe$_2$ as a promising platform, and offers a reliable protocol for the in-lab production of custom bolometers using the vdW assembly technique.

Published
2023
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6. TextANIMAR: Text-based 3D Animal Fine-Grained Retrieval

Author

Le, Trung-Nghia, Nguyen, Tam V., Le, Minh-Quan, Nguyen, Trong-Thuan, Huynh, Viet-Tham, Do, Trong-Le, Le, Khanh-Duy, Tran, Mai-Khiem, Hoang-Xuan, Nhat, Nguyen-Ho, Thang-Long, Nguyen, Vinh-Tiep, Diep, Tuong-Nghiem, Ho, Khanh-Duy, Nguyen, Xuan-Hieu, Tran, Thien-Phuc, Yang, Tuan-Anh, Tran, Kim-Phat, Hoang, Nhu-Vinh, Nguyen, Minh-Quang, Nguyen, E-Ro, Nguyen-Nhat, Minh-Khoi, To, Tuan-An, Huynh-Le, Trung-Truc, Nguyen, Nham-Tan, Luong, Hoang-Chau, Phong, Truong Hoai, Le-Pham, Nhat-Quynh, Pham, Huu-Phuc, Hoang, Trong-Vu, Nguyen, Quang-Binh, Nguyen, Hai-Dang, Sugimoto, Akihiro, and Tran, Minh-Triet

Subjects
Computer Science - Computer Vision and Pattern Recognition
Abstract

3D object retrieval is an important yet challenging task that has drawn more and more attention in recent years. While existing approaches have made strides in addressing this issue, they are often limited to restricted settings such as image and sketch queries, which are often unfriendly interactions for common users. In order to overcome these limitations, this paper presents a novel SHREC challenge track focusing on text-based fine-grained retrieval of 3D animal models. Unlike previous SHREC challenge tracks, the proposed task is considerably more challenging, requiring participants to develop innovative approaches to tackle the problem of text-based retrieval. Despite the increased difficulty, we believe this task can potentially drive useful applications in practice and facilitate more intuitive interactions with 3D objects. Five groups participated in our competition, submitting a total of 114 runs. While the results obtained in our competition are satisfactory, we note that the challenges presented by this task are far from fully solved. As such, we provide insights into potential areas for future research and improvements. We believe we can help push the boundaries of 3D object retrieval and facilitate more user-friendly interactions via vision-language technologies. https://aichallenge.hcmus.edu.vn/textanimar, Comment: Accepted to Computers and Graphics (3DOR, Journal Track)

Published
2023

8. V-FIRST 2.0: Video Event Retrieval with Flexible Textual-Visual Intermediary for VBS 2023

Author

Hoang-Xuan, Nhat, Nguyen, E-Ro, Nguyen-Ho, Thang-Long, Pham, Minh-Khoi, Nguyen, Quang-Thuc, Trang-Trung, Hoang-Phuc, Ninh, Van-Tu, Le, Tu-Khiem, Gurrin, Cathal, Tran, Minh-Triet, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Dang-Nguyen, Duc-Tien, editor, Gurrin, Cathal, editor, Larson, Martha, editor, Smeaton, Alan F., editor, Rudinac, Stevan, editor, Dao, Minh-Son, editor, Trattner, Christoph, editor, and Chen, Phoebe, editor

Published
2023
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12. One-dimensional proximity superconductivity in the quantum Hall regime

Author

Barrier, Julien, primary, Kim, Minsoo, additional, Kumar, Roshan Krishna, additional, Xin, Na, additional, Kumaravadivel, P., additional, Hague, Lee, additional, Nguyen, E., additional, Berdyugin, A. I., additional, Moulsdale, Christian, additional, Enaldiev, V. V., additional, Prance, J. R., additional, Koppens, F. H. L., additional, Gorbachev, R. V., additional, Watanabe, K., additional, Taniguchi, T., additional, Glazman, L. I., additional, Grigorieva, I. V., additional, Fal’ko, V. I., additional, and Geim, A. K., additional

Published
2024
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15. Competency based curriculum for cardiovascular magnetic resonance: A position statement of the Society for Cardiovascular Magnetic Resonance

Author

Nguyen, E. T., Ordovas, K., Herbst, P., Kozor, R., Ng, M. Y., Natale, Luigi, Nijveldt, R., Salgado, R., Sanchez, F., Shah, D., Stojanovska, J., Valente, A. M., Westwood, M., Plein, S., Natale L. (ORCID:0000-0002-7949-5119), Nguyen, E. T., Ordovas, K., Herbst, P., Kozor, R., Ng, M. Y., Natale, Luigi, Nijveldt, R., Salgado, R., Sanchez, F., Shah, D., Stojanovska, J., Valente, A. M., Westwood, M., Plein, S., and Natale L. (ORCID:0000-0002-7949-5119)

Abstract

This position statement guides cardiovascular magnetic resonance (CMR) imaging program directors and learners on the key competencies required for Level II and III CMR practitioners, whether trainees come from a radiology or cardiology background. This document is built upon existing curricula and was created and vetted by an international panel of cardiologists and radiologists on behalf of the Society for Cardiovascular Magnetic Resonance (SCMR).

Published
2024

16. Improving Referring Image Segmentation using Vision-Aware Text Features

Author

Nguyen-Truong, Hai, Nguyen, E-Ro, Vu, Tuan-Anh, Tran, Minh-Triet, Hua, Binh-Son, Yeung, Sai-Kit, Nguyen-Truong, Hai, Nguyen, E-Ro, Vu, Tuan-Anh, Tran, Minh-Triet, Hua, Binh-Son, and Yeung, Sai-Kit

Abstract

Referring image segmentation is a challenging task that involves generating pixel-wise segmentation masks based on natural language descriptions. Existing methods have relied mostly on visual features to generate the segmentation masks while treating text features as supporting components. This over-reliance on visual features can lead to suboptimal results, especially in complex scenarios where text prompts are ambiguous or context-dependent. To overcome these challenges, we present a novel framework VATEX to improve referring image segmentation by enhancing object and context understanding with Vision-Aware Text Feature. Our method involves using CLIP to derive a CLIP Prior that integrates an object-centric visual heatmap with text description, which can be used as the initial query in DETR-based architecture for the segmentation task. Furthermore, by observing that there are multiple ways to describe an instance in an image, we enforce feature similarity between text variations referring to the same visual input by two components: a novel Contextual Multimodal Decoder that turns text embeddings into vision-aware text features, and a Meaning Consistency Constraint to ensure further the coherent and consistent interpretation of language expressions with the context understanding obtained from the image. Our method achieves a significant performance improvement on three benchmark datasets RefCOCO, RefCOCO+ and G-Ref. Code is available at: https://nero1342.github.io/VATEX\_RIS., Comment: 30 pages including supplementary

Published
2024

22. Terrestrial N Cycling in an Endangered Oasis

Author

López-Lozano, Nguyen E., Escalante, Ana E., Barrón-Sandoval, Alberto, Perez-Carbajal, Teresa, Souza, Valeria, Series Editor, Eguiarte, Luis E., Series Editor, García-Oliva, Felipe, editor, and Elser, James, editor

Published
2018
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24. Down Syndrome–Associated Arthritis Cohort in the New Childhood Arthritis and Rheumatology Research Alliance Registry: Clinical Characteristics, Treatment, and Outcomes

Author

Jones, Jordan T., Smith, Chelsey, Becker, Mara L., Lovell, Daniel, Abel, N., Abulaban, K., Adams, A., Adams, M., Agbayani, R., Akoghlanian, S., Al Ahmed, O., Allenspach, E., Alperin, R., Alpizar, M., Amarilyo, G., Anastasopoulos, D., Anderson, E., Andrew, M., Ardalan, K., Ardoin, S., Baker, E., Balboni, I., Balevic, S., Ballenger, L., Ballinger, S., Balmuri, N., Barbar‐Smiley, F., Barillas‐Arias, L., Basiaga, M., Baszis, K., Bell‐Brunson, H., Beltz, E., Benham, H., Benseler, S., Bernal, W., Beukelman, T., Bigley, T., Binstadt, B., Birmingham, J., Black, C., Blakley, M., Bohnsack, J., Boland, J., Boneparth, A., Bowman, S., Brooks, E., Brown, A., Brunner, H., Buckley, M., Buckley, M., Bukulmez, H., Bullington, A., Bullock, D., Cameron, B., Canna, S., Cannon, L., Carpenter, S., Carper, P., Cartwright, V., Cassidy, E., Cerracchio, L., Chalom, E., Chang, J., Chang‐Hoftman, A., Chauhan, V., Chira, P., Chiu, Y., Chundru, K., Clairman, H., Co, D., Collins, K., Confair, A., Conlon, H., Connor, R., Cooper, A., Cooper, J., Cooper, S., Correll, C., Corvalan, R., Cospito, T., Costanzo, D., Cron, R., Curry, M., Dalrymple, A., Davis, A., Davis, C., Davis, C., Davis, T., De Ranieri, D., Dean, J., Dedeoglu, F., DeGuzman, M., Delnay, N., Dempsey, V., DeSantis, E., Dickson, T., Dingle, J., Dionizovik‐Dimanovski, M., Donaldson, B., Dorsey, E., Dover, S., Dowling, J., Drew, J., Driest, K., Drummond, K., Du, Q., Duarte, K., Durkee, D., Duverger, E., Dvergsten, J., Eberhard, A., Eckert, M., Ede, K., Edens, C., Edens, C., Edgerly, Y., Elder, M., Fadrhonc, S., Failing, C., Fair, D., Falcon, M., Favier, L., Feldman, B., Ferguson, I., Ferguson, P., Ferreira, B., Ferrucho, R., Fields, K., Finkel, T., Fitzgerald, M., Fleck, D., Fleming, C., Flynn, O., Fogel, L., Fox, E., Fox, M., Franco, L., Freeman, M., Froese, S., Fuhlbrigge, R., Fuller, J., George, N., Gergely, T., Gerhold, K., Gerstbacher, D., Gilbert, M., Gillispie‐Taylor, M., Giverc, E., Goh, I., Goldberg, T., Goldsmith, D., Gotschlich, E., Gotte, A., Gottlieb, B., Gracia, C., Graham, T., Grevich, S., Griffin, T., Griswold, J., Guevara, M., Guittar, P., Gurion, R., Guzman, M., Hahn, T., Halyabar, O., Hammelev, E., Hance, M., Hansman, E., Hanson, A., Harel, L., Haro, S., Harris, J., Hartigan, E., Hausmann, J., Hay, A., Hayward, K., Heiart, J., Hekl, K., Henderson, L., Henrickson, M., Hersh, A., Hickey, K., Hillyer, S., Hiraki, L., Hiskey, M., Hobday, P., Hoffart, C., Holland, M., Hollander, M., Hong, S., Horwitz, M., Hsu, J., Huber, A., Huggins, J., Hughes, R., Hui‐Yuen, J., Hung, C., Huntington, J., Huttenlocher, A., Ibarra, M., Imundo, L., Inman, C., Iqbal, S., Jackson, A., Jackson, S., James, K., Janow, G., Jaquith, J., Jared, S., Johnson, N., Jones, J., Jones, J., Jones, J., Jones, K., Jones, S., Joshi, S., Jung, L., Justice, C., Justiniano, A., Kahn, P., Karan, N., Kaufman, K., Kemp, A., Kessler, E., Khaleel, M., Khalsa, U., Kienzle, B., Kim, S., Kimura, Y., Kingsbury, D., Kitcharoensakkul, M., Klausmeier, T., Klein, K., Klein‐Gitelman, M., Kosikowski, A., Kovalick, L., Kracker, J., Kramer, S., Kremer, C., Lai, J., Lang, B., Lapidus, S., Lasky, A., Latham, D., Lawson, E., Laxer, R., Lee, P., Lee, P., Lee, T., Lentini, L., Lerman, M., Levy, D., Li, S., Lieberman, S., Lim, L., Lin, C., Ling, N., Lingis, M., Lo, M., Lovell, D., Luca, N., Lvovich, S., Ma, M., Mackey, C., Madison, C., Madison, J., Malla, B., Maller, J., Malloy, M., Mannion, M., Manos, C., Marques, L., Martyniuk, A., Mason, T., Mathus, S., McAllister, L., McCallum, B., McCarthy, K., McConnell, K., McCurdy, D., McCurdy Stokes, P., McGuire, S., McHale, I., McHugh, A., McKibben, K., McMonagle, A., McMullen‐Jackson, C., Meidan, E., Mellins, E., Mendoza, E., Mercado, R., Merritt, A., Michalowski, L., Miettunen, P., Miller, M., Mirizio, E., Misajon, E., Mitchell, M., Modica, R., Mohan, S., Moore, K., Moorthy, L., Morgan, S., Morgan Dewitt, E., Morris, S., Moss, C., Moussa, T., Mruk, V., Mulvhihill, E., Muscal, E., Nahal, B., Nanda, K., Nassi, L., Nativ, S., Natter, M., Neely, J., Nelson, B., Newhall, L., Ng, L., Nguyen, E., Nicholas, J., Nigrovic, P., Nocton, J., Oberle, E., Obispo, B., O’Brien, B., O’Brien, T., O’Connor, M., Oliver, M., Olson, J., O’Neil, K., Onel, K., Orlando, M., Oz, R., Pagano, E., Paller, A., Pan, N., Panupattanapong, S., Paredes, J., Parsons, A., Patel, J., Pentakota, K., Pepmueller, P., Pfeiffer, T., Phillippi, K., Phillippi, K., Ponder, L., Pooni, R., Prahalad, S., Pratt, S., Protopapas, S., Punaro, M., Puplava, B., Quach, J., Quinlan‐Waters, M., Quintero, A., Rabinovich, C., Radhakrishna, S., Rafko, J., Raisian, J., Rakestraw, A., Ramsay, E., Ramsey, S., Reed, A., Reed, A., Reed, A., Reid, H., Reyes, A., Richmond, A., Riebschleger, M., Ringold, S., Riordan, M., Riskalla, M., Ritter, M., Rivas‐Chacon, R., Roberson, S., Robinson, A., Rodela, E., Rodriquez, M., Rojas, K., Ronis, T., Rosenkranz, M., Rosenwasser Raines, N., Rosolowski, B., Rothermel, H., Rothman, D., Roth‐Wojcicki, E., Rouster–Stevens, K., Rubinstein, T., Ruth, N., Saad, N., Sabatino, M., Sabbagh, S., Sadun, R., Sandborg, C., Sanni, A., Sarkissian, A., Savani, S., Scalzi, L., Schanberg, L., Scharnhorst, S., Schikler, K., Schmeling, H., Schmidt, K., Schmitt, E., Schneider, R., Schollaert‐Fitch, K., Schulert, G., Seay, T., Seper, C., Shalen, J., Sheets, R., Shelly, A., Shen, B., Shenoi, S., Shergill, K., Shiff, N., Shirley, J., Shishov, M., Silverman, E., Singer, N., Sivaraman, V., Sletten, J., Smith, A., Smith, C., Smith, J., Smith, J., Smitherman, E., Snider, C., Soep, J., Son, M., Soybilgic, A., Spence, S., Spiegel, L., Spitznagle, J., Sran, R., Srinivasalu, H., Stapp, H., Stasek, J., Steigerwald, K., Sterba Rakovchik, Y., Stern, S., Stevens, A., Stevens, B., Stevenson, R., Stewart, K., Stingl, C., Stokes, J., Stoll, M., Stoops, S., Strelow, J., Stringer, E., Sule, S., Sumner, J., Sundel, R., Sura, A., Sutter, M., Syed, R., Taber, S., Tal, R., Tambralli, A., Taneja, A., Tanner, T., Tapani, S., Tarshish, G., Tarvin, S., Tate, L., Taxter, A., Taylor, J., Terry, M., Tesher, M., Thatayatikom, A., Thomas, B., Ting, T., Tipp, A., Toib, D., Torok, K., Toruner, C., Tory, H., Toth, M., Treemarcki, E., Tse, S., Tubwell, V., Twilt, M., Uriguen, S., Valcarcel, T., Van Mater, H., Vannoy, L., Varghese, C., Vasquez, N., Vazzana, K., Vega‐Fernandes, P., Vehe, R., Veiga, K., Velez, J., Verbsky, J., Volpe, N., von Scheven, E., Vora, S., Wagner, J., Wagner‐Weiner, L., Wahezi, D., Waite, H., Walker, J., Walters, H., Wampler Muskardin, T., Wang, C., Waqar, L., Waterfield, M., Watson, M., Watts, A., Waugaman, B., Weiser, P., Weiss, J., Weiss, P., Wershba, E., White, A., Williams, C., Wise, A., Woo, J., Woolnough, L., Wright, T., Wu, E., Yalcindag, A., Yee, M., Yen, E., Yeung, R., Yomogida, K., Yu, Q., Zapata, R., Zartoshti, A., Zeft, A., Zeft, R., Zemel, L., Zhang, Y., Zhao, Y., Zhu, A., and Zic, C.

Published
2021
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26. Bacterial Diversity and Interaction Networks of Agave lechuguilla Rhizosphere Differ Significantly From Bulk Soil in the Oligotrophic Basin of Cuatro Cienegas

Author

Nguyen E. López-Lozano, Andrea Echeverría Molinar, Elizabeth Alejandra Ortiz Durán, Maribel Hernández Rosales, and Valeria Souza

Subjects
agave microbiome, microbial co-occurrence, keystone species, community assembly, functional traits, Plant culture, SB1-1110
Abstract

Due to the environmental conditions presented in arid zones, it is expected to have a high influence of deterministic processes over the community assemblages. Symbiotic interactions with microorganisms could increase colonization and survival of plants in difficult conditions, independent of the plants physiological and morphological characteristics. In this context, the microbial communities associated to plants that inhabit these types of areas can be a good model to understand the community assembly processes. We investigated the influence of stochastic and deterministic processes in the assemblage of rhizosphere microbial communities of Agave lechuguilla and bulk soil on the Cuatro Cienegas Basin, a site known for its oligotrophic conditions. We hypothesize that rhizospheric microbial communities of A. lechuguilla differ from those of bulk soil as they differ in physicochemical properties of soil and biotic interactions, including not only the plant, but also their microbial co-occurrence networks, it is expected that microbial species usually critical for plant growth and health are more common in the rhizosphere, whereas in the bulk soil microbial species related to the resistance to abiotic stress are more abundant. In order to confirm this hypothesis, 16S rRNA gene was sequenced by Illumina from rhizospheric and bulk soil samples in two seasons, also the physicochemical properties of the soil were determined. Our results showed differences in bacterial diversity, community composition, potential functions, and interaction networks between the rhizosphere samples and the ones from bulk soil. Although community structure arises from a complex interplay between deterministic and stochastic forces, our results suggest that A. lechuguilla recruits specific rhizospheric microbes with functional traits that benefits the plant through growth promotion and nutrition. This selection follows principally a deterministic process that shapes the rhizospheric microbial communities, directed by the plant modifications around the roots but also subjected to the influence of other environmental variables, such as seasonality and soil properties. Interestingly, keystone taxa in the interactions networks, not necessarily belong to the most abundant taxonomic groups, but they have an important role by their functional traits and keeping the connections on the community network.

Published
2020
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27. Humic Substances Mediate Anaerobic Methane Oxidation Linked to Nitrous Oxide Reduction in Wetland Sediments

Author

Edgardo I. Valenzuela, Claudia Padilla-Loma, Nicolás Gómez-Hernández, Nguyen E. López-Lozano, Sergio Casas-Flores, and Francisco J. Cervantes

Subjects
greenhouse gases, anaerobic methanotrophy, wetlands, nitrous oxide, extracellular electron transfer, natural organic matter, Microbiology, QR1-502
Abstract

Humic substances are redox-active organic molecules, which play pivotal roles in several biogeochemical cycles due to their electron-transferring capacity involving multiple abiotic and microbial transformations. Based on the redox properties of humic substances, and the metabolic capabilities of microorganisms to reduce and oxidize them, we hypothesized that they could mediate the anaerobic oxidation of methane (AOM) coupled to the reduction of nitrous oxide (N2O) in wetland sediments. This study provides several lines of evidence indicating the coupling between AOM and the reduction of N2O through an extracellular electron transfer mechanism mediated by the redox active functional groups in humic substances (e.g., quinones). We found that the microbiota of a sediment collected from the Sisal wetland (Yucatán Peninsula, southeastern Mexico) was able to reduce N2O (4.6 ± 0.5 μmol N2O g sed.–1 day–1) when reduced humic substances were provided as electron donor in a close stoichiometric relationship. Furthermore, a microbial enrichment derived from the wetland sediment achieved simultaneous 13CH4 oxidation (1.3 ± 0.1 μmol 13CO2 g sed.–1 day–1) and N2O reduction (25.2 ± 0.5 μmol N2O g sed.–1 day–1), which was significantly dependent on the presence of humic substances as an extracellular electron shuttle. Taxonomic characterization based on 16S rRNA gene sequencing revealed Acinetobacter (a ɣ-proteobacterium), the Rice Cluster I from the Methanocellaceae and an uncultured archaeon from the Methanomicrobiaceae family as the microbes potentially involved in AOM linked to N2O reduction mediated by humic substances. The findings reported here suggest that humic substances might play an important role to prevent the emission of greenhouse gases (CH4 and N2O) from wetland sediments. Further efforts to evaluate the feasibility of this novel mechanism under the natural conditions prevailing in ecosystems must be considered in future studies.

Published
2020
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28. Optical Doppler tomography and spectral Doppler imaging of localized ischemic stroke in a mouse model

Author

Yu, L, Nguyen, E, Liu, G, Rao, B, Choi, B, and Chen, Z

Subjects
Doppler, tomography, interferometry
Abstract

We present a combined optical Doppler tomography/spectral Doppler imaging modality to quantitatively evaluate the dynamic blood circulation and the artery blockage before and after a localized ischemic stroke in a mouse model. Optical Doppler Tomography (ODT) combines the Doppler principle with optical coherence tomography for noninvasive localization and measurement of particle flow velocity in highly scattering media with micrometer scale spatial resolution. Spectral Doppler imaging (SDI) provides complementary temporal flow information to the spatially distributed flow information of Doppler imaging. Fast, repeated, ODT scans across an entire vessel were performed to record flow dynamic information with high temporal resolution of cardiac cycles. Spectral Doppler analysis of continuous Doppler images demonstrates how the velocity components and longitudinally projected flow-volume-rate change over time for scatters within the imaging volume using spectral Doppler waveforms. Furthermore, vascular conditions can be quantified with various Doppler-angle-independent flow indices. Non-invasive in-vivo mice experiments were performed to evaluate microvascular blood circulation of a localized ischemic stroke mouse model. © 2010 Copyright SPIE - The International Society for Optical Engineering.

Published
2010

32. Hopping charge transport in hydrogenated amorphous silicon–germanium alloy thin films.

Author

Stolik, L., Eslamisaray, M. A., Nguyen, E., Kortshagen, U. R., and Kakalios, J.

Subjects
AMORPHOUS alloys, SILICON alloys, THIN films, HOPPING conduction, THERMOELECTRIC power, AMORPHOUS semiconductors
Abstract

Measurements of the dark conductivity and thermoelectric power in hydrogenated amorphous silicon–germanium alloys (a-Si1-xGex:H) reveal that charge transport is not well described by an Arrhenius expression. For alloys with concentrations of Ge below 20%, anomalous hopping conductivity is observed with a power-law exponent of 3/4, while the temperature dependence of the conductivity of alloys with higher Ge concentrations is best fit by a combination of anomalous hopping and a power-law temperature dependence. The latter has been attributed to charge transport via multi-phonon hopping. Corresponding measurements of the Seebeck coefficient reveal that the thermopower is n-type for the purely a-Si:H and a-Ge:H samples but that it exhibits a transition from negative to positive values as a function of the Ge content and temperature. These findings are interpreted in terms of conduction via hopping through either exponential band tail states or dangling bond defects, suggesting that the concept of a mobility edge, accepted for over five decades, may not be necessary to account for charge transport in amorphous semiconductors. [ABSTRACT FROM AUTHOR]

Published
2022
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43. The link between lexical semantic features and children’s comprehension of English verbal be-passives

Author

Nguyen, E, Nguyen, E, Pearl, L, Nguyen, E, Nguyen, E, and Pearl, L

Abstract

Children seem to be relatively delayed in their comprehension of the verbal be-passive in English, compared to their acquisition of other constructions of object-movement such as wh-questions and unaccusatives. Prior work has found that children’s performance on these passives can be affected by the verb’s lexical semantics. Through a meta-analysis of experimental studies assessing English-speaking children’s age of acquisition for the verbal be- passive, we identify a developmental trajectory composed of five classes, where each class has a distinct lexical semantic profile. A Truth-Value Judgment (TVJ) Task assessing English-speaking children’s comprehension of verbal be-passives supports this developmental trajectory. Together, the meta-analysis and TVJ study underscore the importance of lexical semantics for understanding the development of the English verbal be-passive.

Published
2021

46. Linking below‐ and aboveground indicators under different forest restoration interventions in a mosaic landscape with different land‐use legacies.

Author

Alfaro García, Rosaura G., Douterlungne, David, López Lozano, Nguyen E., Huber‐Sannwald, Elisabeth, and García‐Oliva, Felipe

Subjects
FOREST restoration, FOREST degradation, LANDSCAPES, LANDSCAPE assessment, RHIZOBACTERIA, RESTORATION ecology
Abstract

Deforestation and forest degradation continue at alarming rates. Landowners often clear forest patches for alternative use, creating landscape mosaics of different land‐use legacies. Ecological restoration is usually monitored by aboveground processes, while belowground processes are far less studied. We addressed how the abundance and activity of nutrient improvement bacteria contribute to restoration success, considering different restoration interventions and land‐use legacies. We assessed the abundance and potential activity of N‐fixing and P‐mineralizing bacteria in the rhizosphere of 279 two‐year‐old Quercus mexicana plantlets in a disturbed oak forest in central Mexico. We analyzed the differences across landscape patches (eroded landslide, pastureland, and forest) of four common restoration interventions: passive restoration, artificial shading, topsoil translocation, and combining both treatments. Restoration interventions modified soil functioning differently across landscape patches with a significant increase of P‐mineralizing bacteria abundance and potential activity in the landslide and pastureland. In contrast, N‐fixing bacteria increased only in the landslide site where we registered the lowest organic matter content. Surprisingly, interventions that enhance bacterial activity and abundance do not necessarily improve short‐term seedling performance. We recommend considering the landscape heterogeneity to better match the restoration interventions with the prevailing degradation factor in each landscape patch. Also, combining restoration strategies does not necessarily result in synergy and may imply a useless expense of resources. Finally, monitoring soil health provides novel insights to understand restoration trajectories that remain undetected when focusing only on seedling performance. [ABSTRACT FROM AUTHOR]

Published
2023
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50. Flexible interactive retrieval SysTem 3.0 for visual lifelog exploration at LSC 2022

Author

Hoang-Xuan, Nhat, Trang-Trung, Hoang-Phuc, Nguyen, E-Ro, Le, Thanh-Cong, Tran, Mai-Khiem, Le, Tu-Khiem, Ninh, Van-Tu, Gurrin, Cathal, Tran, Minh-Triet, Hoang-Xuan, Nhat, Trang-Trung, Hoang-Phuc, Nguyen, E-Ro, Le, Thanh-Cong, Tran, Mai-Khiem, Le, Tu-Khiem, Ninh, Van-Tu, Gurrin, Cathal, and Tran, Minh-Triet

Abstract

Building a retrieval system with lifelogging data is more complicated than with ordinary data due to the redundancies, blurriness, massive amount of data, various sources of information accompanying lifelogging data, and especially the ad-hoc nature of queries. The Lifelog Search Challenge (LSC) is a benchmarking challenge that encourages researchers and developers to push the boundaries in lifelog retrieval. For LSC'22, we develop FIRST 3.0, a novel and flexible system that leverages expressive cross-domain embeddings to enhance the searching process. Our system aims to adaptively capture the semantics of an image at different levels of detail. We also propose to augment our system with an external search engine to help our system with initial visual examples for unfamiliar concepts. Finally, we organize image data in hierarchical clusters based on their visual similarity and location to assist users in data exploration. Experiments show that our system is both fast and effective in handling various retrieval scenarios.

Published
2022
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