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Search Results: 1 - 10 of 26779 matches for " Anthony Kim "
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On Network Coding Capacity - Matroidal Networks and Network Capacity Regions
Anthony Kim
Mathematics , 2011,
Abstract: One fundamental problem in the field of network coding is to determine the network coding capacity of networks under various network coding schemes. In this thesis, we address the problem with two approaches: matroidal networks and capacity regions. In our matroidal approach, we prove the converse of the theorem which states that, if a network is scalar-linearly solvable then it is a matroidal network associated with a representable matroid over a finite field. As a consequence, we obtain a correspondence between scalar-linearly solvable networks and representable matroids over finite fields in the framework of matroidal networks. We prove a theorem about the scalar-linear solvability of networks and field characteristics. We provide a method for generating scalar-linearly solvable networks that are potentially different from the networks that we already know are scalar-linearly solvable. In our capacity region approach, we define a multi-dimensional object, called the network capacity region, associated with networks that is analogous to the rate regions in information theory. For the network routing capacity region, we show that the region is a computable rational polytope and provide exact algorithms and approximation heuristics for computing the region. For the network linear coding capacity region, we construct a computable rational polytope, with respect to a given finite field, that inner bounds the linear coding capacity region and provide exact algorithms and approximation heuristics for computing the polytope. The exact algorithms and approximation heuristics we present are not polynomial time schemes and may depend on the output size.
Welfare Maximization with Deferred Acceptance Auctions in Reallocation Problems
Anthony Kim
Computer Science , 2015,
Abstract: We design approximate weakly group strategy-proof mechanisms for resource reallocation problems using Milgrom and Segal's deferred acceptance auction framework: the radio spectrum and network bandwidth reallocation problems in the procurement auction setting and the cost minimization problem with set cover constraints in the selling auction setting. Our deferred acceptance auctions are derived from simple greedy algorithms for the underlying optimization problems and guarantee approximately optimal social welfare (cost) of the agents retaining their rights (contracts). In the reallocation problems, we design procurement auctions to purchase agents' broadcast/access rights to free up some of the resources such that the unpurchased rights can still be exercised with respect to the remaining resources. In the cost minimization problem, we design a selling auction to sell early termination rights to agents with existing contracts such that some minimal constraints are still satisfied with remaining contracts. In these problems, while the "allocated" agents transact, exchanging rights and payments, the objective and feasibility constraints are on the "rejected" agents.
Amanita bisporigera-Induced Hepatic Failure: A Fatal Case of Mushroom Ingestion
Anthony Nici,Sang Kim
Case Reports in Hepatology , 2011, DOI: 10.1155/2011/936867
Abstract: Wild mushroom poisoning from the genus Amanita is a medical emergency, with Amanita phalloides being the most common offender. Patients may complain of nausea, vomiting, diarrhea and/or abdominal pain. If not aggressively treated, fulminant hepatic failure may develop within several days of ingestion. In this case report, a patient poisoned with Amanita bisporigera is described, along with the typical clinical presentation, patient outcomes, and treatment options for dealing with an Amanita mushroom poisoning.
Binaural Sound Localizer for Azimuthal Movement Detection Based on Diffraction
Keonwook Kim,Anthony Choi
Sensors , 2012, DOI: 10.3390/s120810584
Abstract: Sound localization can be realized by utilizing the physics of acoustics in various methods. This paper investigates a novel detection architecture for the azimuthal movement of sound source based on the interaural level difference (ILD) between two receivers. One of the microphones in the system is surrounded by barriers of various heights in order to cast the direction dependent diffraction of the incoming signal. The gradient analysis of the ILD between the structured and unstructured microphone demonstrates the rotation directions as clockwise, counter clockwise, and no rotation of the sound source. Acoustic experiments with different types of sound source over a wide range of target movements show that the average true positive and false positive rates are 67% and 16%, respectively. Spectral analysis demonstrates that the low frequency delivers decreased true and false positive rates and the high frequency presents increases of both rates, overall.
Scalar-linear Solvability of Matroidal Networks Associated with Representable Matroids
Anthony Kim,Muriel Medard
Mathematics , 2010,
Abstract: We study matroidal networks introduced by Dougherty et al. We prove the converse of the following theorem: If a network is scalar-linearly solvable over some finite field, then the network is a matroidal network associated with a representable matroid over a finite field. It follows that a network is scalar-linearly solvable if and only if the network is a matroidal network associated with a representable matroid over a finite field. We note that this result combined with the construction method due to Dougherty et al. gives a method for generating scalar-linearly solvable networks. Using the converse implicitly, we demonstrate scalar-linear solvability of two classes of matroidal networks: networks constructed from uniform matroids and those constructed from graphic matroids.
Computing Bounds on Network Capacity Regions as a Polytope Reconstruction Problem
Anthony Kim,Muriel Medard
Mathematics , 2011,
Abstract: We define a notion of network capacity region of networks that generalizes the notion of network capacity defined by Cannons et al. and prove its notable properties such as closedness, boundedness and convexity when the finite field is fixed. We show that the network routing capacity region is a computable rational polytope and provide exact algorithms and approximation heuristics for computing the region. We define the semi-network linear coding capacity region, with respect to a fixed finite field, that inner bounds the corresponding network linear coding capacity region, show that it is a computable rational polytope, and provide exact algorithms and approximation heuristics. We show connections between computing these regions and a polytope reconstruction problem and some combinatorial optimization problems, such as the minimum cost directed Steiner tree problem. We provide an example to illustrate our results. The algorithms are not necessarily polynomial-time.
Welfare Maximization with Production Costs: A Primal Dual Approach
Zhiyi Huang,Anthony Kim
Computer Science , 2014,
Abstract: We study online combinatorial auctions with production costs proposed by Blum et al. using the online primal dual framework. In this model, buyers arrive online, and the seller can produce multiple copies of each item subject to a non-decreasing marginal cost per copy. The goal is to allocate items to maximize social welfare less total production cost. For arbitrary (strictly convex and differentiable) production cost functions, we characterize the optimal competitive ratio achievable by online mechanisms/algorithms. We show that online posted pricing mechanisms, which are incentive compatible, can achieve competitive ratios arbitrarily close to the optimal, and construct lower bound instances on which no online algorithms, not necessarily incentive compatible, can do better. Our positive results improve or match the results in several previous work, e.g., Bartal et al., Blum et al., and Buchbinder and Gonen. Our lower bounds apply to randomized algorithms and resolve an open problem by Buchbinder and Gonen.
Activation of Silenced Cytokine Gene Promoters by the Synergistic Effect of TBP-TALE and VP64-TALE Activators
Kim Anthony, Abhijit More, Xiaoliu Zhang
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0095790
Abstract: Recent work has shown that the combinatorial use of multiple TALE activators can selectively activate certain cellular genes in inaccessible chromatin regions. In this study, we aimed to interrogate the activation potential of TALEs upon transcriptionally silenced immune genes in the context of non-immune cells. We designed a unique strategy, in which a single TALE fused to the TATA-box binding protein (TBP-TALE) is coupled with multiple VP64-TALE activators. We found that our strategy is significantly more potent than multiple TALE activators alone in activating expression of IL-2 and GM-CSF in diverse cell origins in which both genes are otherwise completely silenced. Chromatin analysis revealed that the gene activation was due in part to displacement of a distinctly positioned nucleosome. These studies provide a novel epigenetic mechanism for artificial gene induction and have important implications for targeted cancer immunotherapy, DNA vaccine development, as well as rational design of TALE activators.
Testing the Effects of an Introduced Palm on a Riparian Invertebrate Community in Southern California
Theresa Sinicrope Talley, Kim-Chi Nguyen, Anthony Nguyen
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0042460
Abstract: Despite the iconic association of palms with semi-arid regions, most are introduced and can invade natural areas. Along the San Diego River (San Diego, California, USA), the introduced Canary Island date palm (Phoenix canariensis) forms dense patches among native riparian shrubs like arroyo willow (Salix lasiolepis). The structural differences between the palm and native shrubs are visually obvious, but little is known about palm’s effects on the ecosystem. We tested for the effects of the palm on a riparian invertebrate community in June 2011 by comparing the faunal and environmental variables associated with palm and willow canopies, trunks and ground beneath each species. The palm invertebrate community had lower abundance and diversity, fewer taxa feeding on the host (e.g., specialized hemipterans), and more taxa likely using only the plant’s physical structure (e.g., web-builders, oak moths, willow hemipterans). There were no observed effects on the ground-dwelling fauna. Faunal differences were due to the physical and trophic changes associated with palm presence, namely increased canopy density, unpalatable leaves, trunk rugosity, and litter accumulations. Palm presence and resulting community shifts may have further ecosystem-level effects through alteration of physical properties, food, and structural resources. These results were consistent with a recent study of invasive palm effects on desert spring arthropods, illustrating that effects may be relatively generalizable. Since spread of the palm is largely localized, but effects are dramatic where it does occur, we recommend combining our results with several further investigations in order to prioritize management decisions.
Guest Editorial
Ebroul Izquierdo,Anthony TS Ho,Hyoung Joong Kim,Qianni Zhang
Journal of Multimedia , 2010, DOI: 10.4304/jmm.5.2.93-94
Abstract: Over the last two decades, digital video technology has witnessed an explosive growth in both the diversity of techniques and its range of applications. As a consequence, we are also witnessing a dramatic expansion of the stocks of digital content. This in turn, is generating a critical need for systems and tools able to automatically structure and understand visual information. Visual Information Engineering embraces research and development related to image processing, machine vision and visual communications. Recent trends have been directed towards investigating important interactions between visual information retrieval, visualisation and advanced coding and streaming of images and video. The aim is to exploit techniques developed over the years to enable interaction and more advanced multimedia applications. The objective of this special issue is to collate and disseminate few relevant achievements of researchers working on visual information engineering. High quality contributions addressing related theoretical and practical aspects were received. After a thorough review process a total of six papers out of 14 submissions were selected. The first paper addresses the challenging problem of automatic recognition of highlights from videos for content-based indexing and retrieval applications. Ren et al. propose techniques to solve this problem using knowledge supported extraction of semantics, and employing compresseddomain processing for efficiency. In the next paper Badii et al., introduce a framework for process management support in the context of media production and more specifically 3D cinematographic immersive and interactive production. The authors present a holistic approach to software engineering applied to media production modelling to ensure design correctness, completeness and effectiveness. The focus of the designed application is on information and metadata management throughout the process in a similar fashion to that achieved in Decision Support Systems (DSS) to facilitate well-grounded business decisions. The paper sets out the aims and objectives and the methodology deployed. In the third paper, Li and Liu present a novel cross-layer approach to multiuser H.264/AVC video stream
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