| 410291. |
- Kim, Thanh Tung, et al.
(författare)
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On the DMT-Optimality of Nondynamic DF Relaying in Asymmetric Nakagami Fading Channels
- 2010
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 56:7, s. 3304-3309
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Tidskriftsartikel (refereegranskat)abstract
- The optimality of nondynamic DF relaying over a general three-node Nakagami fading channel in terms of the diversity-multiplexing tradeoff (DMT) is established. In particular, when the fading of the relay-source link is less severe than that of the relay-destination link, both orthogonal and nonorthogonal DF protocols are shown to be DMT-optimal over certain ranges of the multiplexing gains. It is also shown that when the multiplexing gains are sufficiently high, the DMT of the DF protocols is completely independent of the statistical properties of the relay-destination link.
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| 410292. |
- Kim, Thanh Tung, et al.
(författare)
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On the expected rate of slowly fading channels with quantized side information
- 2007
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Ingår i: IEEE Transactions on Communications. - : IEEE Communications Society. - 0090-6778 .- 1558-0857. ; 55:4, s. 820-829
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Tidskriftsartikel (refereegranskat)abstract
- We study a multiple-layer variable-rate system employing quantized feedback to maximize the expected rate over a single-input single-output slowly fading Gaussian channel. The transmitter uses partial channel-state information, which is obtained via an optimized resolution-constrained feedback link, to adapt the power and to assign code layer rates, subject to different power constraints. To systematically design the system parameters, we develop a simple iterative algorithm that successfully exploits results in the study of parallel broadcast channels. We present the necessary and sufficient conditions for single-layer coding to be optimal, irrespective of the number of code layers that the system can afford. Unlike in the ergodic case, even coarsely quantized feed-back is shown to improve the expected rate considerably. Our results also indicate that with as little as one bit of feedback information, the role of multilayer coding reduces significantly.
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| 410293. |
- Kim, Thanh Tung, et al.
(författare)
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Quantifying the Loss of Compress-Forward Relaying Without Wyner-Ziv Coding
- 2009
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Ingår i: IEEE Transactions on Information Theory. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9448 .- 1557-9654. ; 55:4, s. 1529-1533
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Tidskriftsartikel (refereegranskat)abstract
- The compress-and-forward (CF) strategy achieves the optimal diversity-multiplexing tradeoff (DMT) of a three-node half-duplex relay network in slow fading, under the assumption that the relay has perfect knowledge of all three channel coefficients and that the relay makes use of Wyner-Ziv (WZ) source coding with side information. This paper studies the achievable DMT of the same network when the relay is constrained to make use of standard (non-WZ) source coding. Under a short-term power constraint at the relay, using source coding without side information results in a significant loss in terms of the DMT. For multiplexing gains r <= 2/3 this loss can be fully compensated for by using power control at the relay. On the contrary, for r is an element of (2/3, 1), the loss with respect to WZ coding remains significant.
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| 410294. |
- Kim, T. W., et al.
(författare)
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Interannual Variation of Modified Circumpolar Deep Water in the Dotson-Getz Trough, West Antarctica
- 2021
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Ingår i: Journal of Geophysical Research: Oceans. - 2169-9275. ; 126:12
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Tidskriftsartikel (refereegranskat)abstract
- Widespread ice shelf thinning has been recorded in the Amundsen Sea in recent decades, driven by basal melting and intrusions of relatively warm Circumpolar Deep Water (CDW) onto the continental shelf. The Dotson Ice Shelf (DIS) is located to the south of the Amundsen Sea polynya, and has a high basal melting rate because modified CDW (mCDW) fills the Dotson-Getz Trough (DGT) and reaches the base of the ice shelf. Here, hydrographic data in the DGT obtained during seven oceanographic surveys from 2007 to 2018 were used to study the interannual variation in mCDW volume and properties and their causes. Although mCDW volume showed relatively weak interannual variations at the continental shelf break, these variations intensified southward and reached a maximum in front of the DIS. There, the mCDW volume was ∼8,000km3 in 2007, rapidly decreased to 4,700km3 in 2014 before rebounding to 7,300km3 in 2018. We find that such interannual variability is coherent with local Ekman pumping integrated along the DGT modulated by the presence of sea ice, and complementing earlier theories involving shelf break winds only. The interannual variability in strength of the dominant south-southeast coastal wind modulates the amplitude of Ekman upwelling along the eastern boundary of the Amundsen Sea polynya during the austral summers of the surveyed years, apparently leading to change in the volume of mCDW along the DGT. We note a strong correlation between the wind variability and the longitudinal location of the Amundsen Sea Low. © 2021. The Authors.
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| 410295. |
- Kim, T. W., et al.
(författare)
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Is Ekman pumping responsible for the seasonal variation of warm circumpolar deep water in the Amundsen Sea?
- 2017
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Ingår i: Continental Shelf Research. - : Elsevier BV. - 0278-4343 .- 1873-6955. ; 132, s. 38-48
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Tidskriftsartikel (refereegranskat)abstract
- © 2016 The AuthorsEkman pumping induced by horizontally varying wind and sea ice drift is examined as an explanation for observed seasonal variation of the warm layer thickness of circumpolar deep water on the Amundsen Sea continental shelf. Spatial and temporal variation of the warm layer thickness in one of the deep troughs on the shelf (Dotson Trough) was measured during two oceanographic surveys and a two-year mooring deployment. A hydrographic transect from the deep ocean, across the shelf break, and into the trough shows a local elevation of the warm layer at the shelf break. On the shelf, the water flows south-east along the trough, gradually becoming colder and fresher due to mixing with cold water masses. A mooring placed in the trough shows a thicker and warmer layer in February and March (late summer/early autumn) and thinner and colder layer in September, October and November (late winter/early spring). The amplitude of this seasonal variation is up to 60 m. In order to investigate the effects of Ekman pumping, remotely sensed wind (Antarctic Mesoscale Prediction System wind data) and sea ice velocity and concentration (EASE Polar Pathfinder) were used. From the estimated surface stress field, the Ekman transport and Ekman pumping were calculated. At the shelf break, where the warm layer is elevated, the Ekman pumping shows a seasonal variation correlating with the mooring data. Previous studies have not been able to show a correlation between observed wind and bottom temperature, but it is shown here that when sea ice drift is taken into account the Ekman pumping at the outer shelf correlates with bottom temperature in Dotson Trough. The reason why the Ekman pumping varies seasonally at the shelf break appears to be the migration of the ice edge in the expanding polynya in combination with the wind field which on average is westward south of the shelf break.
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| 410296. |
- Kim, Tae-Yun, et al.
(författare)
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3D Texture Analysis in Renal Cell Carcinoma Tissue Image Grading
- 2014
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Ingår i: Computational & Mathematical Methods in Medicine. - : Hindawi Publishing Corporation. - 1748-670X .- 1748-6718. ; 2014, s. 536217:1-12
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Tidskriftsartikel (refereegranskat)abstract
- One of the most significant processes in cancer cell and tissue image analysis is the efficient extraction of features for grading purposes. This research applied two types of three-dimensional texture analysis methods to the extraction of feature values from renal cell carcinoma tissue images, and then evaluated the validity of the methods statistically through grade classification. First, we used a confocal laser scanning microscope to obtain image slices of four grades of renal cell carcinoma, which were then reconstructed into 3D volumes. Next, we extracted quantitative values using a 3D gray level cooccurrence matrix (GLCM) and a 3D wavelet based on two types of basis functions. To evaluate their validity, we predefined 6 different statistical classifiers and applied these to the extracted feature sets. In the grade classification results, 3D Haar wavelet texture features combined with principal component analysis showed the best discrimination results. Classification using 3D wavelet texture features was significantly better than 3D GLCM, suggesting that the former has potential for use in a computer-based grading system.
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| 410297. |
- Kim, T. -Y, et al.
(författare)
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Decelerating agricultural society : Theoretical and historical perspectives
- 2010
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Ingår i: Technological forecasting & social change. - : Elsevier BV. - 0040-1625 .- 1873-5509. ; 77:3, s. 479-499
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Tidskriftsartikel (refereegranskat)abstract
- In general, societies are divided into agricultural and industrial types. This study presents theoretical and historical perspectives on decelerating agricultural societies. Agricultural demand and supply play major roles in society development. Three descriptions of an agricultural society and theories of its deceleration patterns are presented: the neo-classical production function, stage theory, and induced innovation. Two important cases of decelerating agricultural societies and their ultimate replacement by industrial societies, medieval Europe and nineteenth- and twentieth-century United States, are examined. The limitations of decelerating agricultural societies with a focus on structural problems, impacts of industrial structure, and problems of agriculture in market and non-market areas, are also discussed. The position of agriculture as described by economic development theory is established by analyzing the stages of economic development, the theory of structural change, and the theory of leading industry. Finally, the transition from an agricultural to a commercial society is described with a focus on the formation, development, value creation, and structural limitations of a commercial society. ©2009 Elsevier Inc. All rights reserved.
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| 410298. |
- Kim, Tae Young, et al.
(författare)
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Dna polymerase alpha subunit b is a binding protein for erlotinib resistance in non-small cell lung cancer
- 2020
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Ingår i: Cancers. - : MDPI AG. - 2072-6694. ; 12:9, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Erlotinib inhibits epithelial growth factor receptor (EGFR) kinase activity and is used to treat non-small cell lung cancer (NSCLC). Despite its high efficacy, recurrence can occur in patients who become resistant to the drug. To address the underlying mechanism of Erlotinib resistance, we investigated additional mechanisms related to mode-of-drug-action, by multiple protein-binding interactions, besides EGFR by using drug affinity responsive target stability (DARTS) and liquid chromatography-mass spectrometry (LC-MS/MS) methods with non-labeled Erlotinib. DNA polymerase alpha subunit B (POLA2) was identified as a new Erlotinib binding protein that was validated by the DARTS platform, complemented with cellular thermal shift assays. Genetic knock-down of POLA2 promoted the anti-proliferative effect of the drug in the Erlotinib-resistant cell line H1299 with high POLA2 expression, whereas the overexpression of POLA2 restored anti-proliferative effects in the Erlotinib-sensitive cell line HCC827 with low POLA2 expression. Importantly, POLA2 expression levels in four NSCLC cell lines were positively correlated with anti-proliferative Erlotinib efficacy (Pearson correlation coefficient, R = 0.9886). These results suggest that POLA2 is a novel complementary target protein of Erlotinib, and could clinically provide validity as a surrogate marker for drug resistance in patients with NSCLC.
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| 410299. |
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| 410300. |
- Kim, Tae-Yun, et al.
(författare)
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Three-dimensional texture analysis of renal cell carcinoma cell nuclei for computerized automatic grading
- 2010
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Ingår i: Journal of medical systems. - Netherlands : Springer. - 0148-5598 .- 1573-689X. ; 34:4, s. 709-716
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Tidskriftsartikel (refereegranskat)abstract
- The extraction of important features in cancer cell image analysis is a key process in grading renal cell carcinoma. In this study, we analyzed the three-dimensional chromatin texture of cell nuclei based on digital image cytometry. Individual images of 2,423 cell nuclei were extracted from 80 renal cell carcinomas (RCCs) using confocal laser scanning microscopy (CLSM). First, we applied the 3D texture mapping method to render the volume of entire tissue sections. Then, we determined the chromatin texture quantitatively by calculating 3D gray level co-occurrence matrices and 3D run length matrices. Finally, to demonstrate the suitability of 3D texture features for classification, we performed a discriminant analysis. In addition, we conducted a principal component analysis to obtain optimized texture features. Automatic grading of cell nuclei using 3D texture features had an accuracy of 78.30%. Combining 3D textural and 3D morphological features improved the accuracy to 82.19%.
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