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2012

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Signal To Noise Ratio Estimation Using The Expectation Maximization Algorithm, Ahmed Almradi Jan 2012

Signal To Noise Ratio Estimation Using The Expectation Maximization Algorithm, Ahmed Almradi

Theses

Signal to Noise Ratio (SNR) estimation when the transmitted symbols are unknown is a common problem in many communication systems, especially those which require an accurate SNR estimation. For instance, modern wireless communication systems usually require accurate estimate of SNR without knowledge of the transmitted symbols. In addition, SNR estimation is required in order to perform efficient signal detection, power control, and adaptive modulation In this study, Non data Aided (NDA) SNR estimation for Binary Phase Shift Keying (PBSK) and Quadrature Phase Shift Keying (QPSK) using the Expectation Maximization (EM) algorithm is developed. The assumption here is that the received …

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On Some Order 6 Non-Symplectic Automorphisms Of Elliptic K3 Surfaces, Jimmy J. Dillies Jan 2012

On Some Order 6 Non-Symplectic Automorphisms Of Elliptic K3 Surfaces, Jimmy J. Dillies

Mathematical Sciences: Faculty Publications

We classify primitive non-symplectic automorphisms of order 6 on K3 surfaces. We show how their study can be reduced to the study of non-symplectic automorphisms of order 3 and to a local analysis of the fixed loci. In particular, we determine the possible fixed loci and show that when the Picard lattice is fixed, K3 surfaces come in mirror pairs.

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Introduction To Special Section On Recent Advances In The Study Of Optical Variability In The Near-Surface And Upper Ocean, T. Dickey, M. L. Banner, P. Bhandari, T. Boyd, L. Carvalho, O. Wurl Jan 2012

Introduction To Special Section On Recent Advances In The Study Of Optical Variability In The Near-Surface And Upper Ocean, T. Dickey, M. L. Banner, P. Bhandari, T. Boyd, L. Carvalho, O. Wurl

OES Faculty Publications

Optical variability occurs in the near-surface and upper ocean on very short time and space scales (e.g., milliseconds and millimeters and less) as well as greater scales. This variability is caused by solar, meteorological, and other physical forcing as well as biological and chemical processes that affect optical properties and their distributions, which in turn control the propagation of light across the air-sea interface and within the upper ocean. Recent developments in several technologies and modeling capabilities have enabled the investigation of a variety of fundamental and applied problems related to upper ocean physics, chemistry, and light propagation and utilization …

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Novel Lineages Of Prochlorococcus And Synechococcus In The Global Oceans, Sijun Huang, Steven W. Wilhelm, H. Rodger Harvey, Karen Taylor, Nianzhi Jiao, Feng Chen Jan 2012

Novel Lineages Of Prochlorococcus And Synechococcus In The Global Oceans, Sijun Huang, Steven W. Wilhelm, H. Rodger Harvey, Karen Taylor, Nianzhi Jiao, Feng Chen

OES Faculty Publications

Picocyanobacteria represented by Prochlorococcus and Synechococcus have an important role in oceanic carbon fixation and nutrient cycling. In this study, we compared the community composition of picocyanobacteria from diverse marine ecosystems ranging from estuary to open oceans, tropical to polar oceans and surface to deep water, based on the sequences of 16S-23S rRNA internal transcribed spacer (ITS). A total of 1339 ITS sequences recovered from 20 samples unveiled diverse and several previously unknown clades of Prochlorococcus and Synechococcus. Six high-light (HL)-adapted Prochlorococcus clades were identified, among which clade HLVI had not been described previously. Prochlorococcus clades HLIII, HLIV and …

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Diversity, Distribution, And Expression Of Diazotroph Nifh Genes In Oxygen-Deficient Waters Of The Arabian Sea, Amal Jayakumar, Mamoon M. D. Al-Rshadat, Bess B. Ward, Margaret R. Mulholland Jan 2012

Diversity, Distribution, And Expression Of Diazotroph Nifh Genes In Oxygen-Deficient Waters Of The Arabian Sea, Amal Jayakumar, Mamoon M. D. Al-Rshadat, Bess B. Ward, Margaret R. Mulholland

OES Faculty Publications

The Arabian Sea oxygen minimum zone (OMZ), the largest suboxic region in the world's oceans, is responsible for up to half of the global mesopelagic fixed nitrogen ( N ) loss from the ocean via denitrification and anammox. Dinitrogen (N2) fixation is usually attributed to cyanobacteria in the surface ocean. Model prediction and physiological inhibition of N2 fixation by oxygen, however, suggest that N2 fixation should be enhanced near the oxygen-deficient zone (ODZ) of the Arabian Sea. N2 fixation and cyanobacterial nifH genes (the gene encoding dinitrogenase reductase) have been reported in surface waters overlying …

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Database Of Diazotrophs In Global Ocean: Abundance, Biomass, And Nitrogen Fixation Rates, Y. W. Luo, S. C. Doney, L. A. Anderson, M. Benavides, I. Berman-Frank, A. Bode, S. Bonnet, K. H. Boström, D. Böttjer, D. G. Capone, M. R. Mulholland Jan 2012

Database Of Diazotrophs In Global Ocean: Abundance, Biomass, And Nitrogen Fixation Rates, Y. W. Luo, S. C. Doney, L. A. Anderson, M. Benavides, I. Berman-Frank, A. Bode, S. Bonnet, K. H. Boström, D. Böttjer, D. G. Capone, M. R. Mulholland

OES Faculty Publications

Marine N2 fixing microorganisms, termed di-azotrophs, are a key functional group in marine pelagic ecosystems. The biological fixation of dinitrogen (N2) to bioavailable nitrogen provides an important new source of nitrogen for pelagic marine ecosystems and influences primary productivity and organic matter export to the deep ocean. As one of a series of efforts to collect biomass and rates specific to different phytoplankton functional groups, we have constructed a database on diazotrophic organisms in the global pelagic upper ocean by compiling about 12 000 direct field measurements of cyanobacterial diazotroph abundances (based on microscopic cell counts or …

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The Role Of Larval Dispersal In Metapopulation Gene Flow: Local Population Dynamics Matter, Daphne M. Munroe, John M. Klinck, Eileen E. Hofmann, Eric N. Powell Jan 2012

The Role Of Larval Dispersal In Metapopulation Gene Flow: Local Population Dynamics Matter, Daphne M. Munroe, John M. Klinck, Eileen E. Hofmann, Eric N. Powell

OES Faculty Publications

The degree of genetic connectivity among populations in a metapopulation has direct consequences for species evolution, development of disease resistance, and capacity of a metapopulation to adapt to climate change. This study used a metapopulation model that integrates population dynamics, dispersal, and genetics within an individual-based model framework to examine the mechanisms and dynamics of genetic connectivity within a metapopulation. The model was parameterized to simulate four populations of oysters (Crassostrea virginica) from Delaware Bay on the mid-Atlantic coast of the United States. Differences among the four populations include a strong spatial gradient in mortality, a spatial gradient …

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Impact Of Abrupt Deglacial Climate Change On Tropical Atlantic Subsurface Temperatures, Matthew W. Schmidt, Ping Chang, Jennifer E. Hertzberg, Theodore R. Them Ii, Link Li, Bette L. Otto-Bliesner Jan 2012

Impact Of Abrupt Deglacial Climate Change On Tropical Atlantic Subsurface Temperatures, Matthew W. Schmidt, Ping Chang, Jennifer E. Hertzberg, Theodore R. Them Ii, Link Li, Bette L. Otto-Bliesner

OES Faculty Publications

Both instrumental data analyses and coupled ocean-atmosphere models indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly linked to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes. Although a slowdown of AMOC results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming because of rapid reorganizations of ocean circulation patterns at intermediate water depths. Here, we reconstruct high-resolution temperature records using oxygen isotope values and Mg/Ca ratios in both surface- and sub-thermocline-dwelling planktonic foraminifera from a sediment core located in the TNA over the last 22 ky. …

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Deglacial Variability Of Antarctic Intermediate Water Penetration Into The North Atlantic From Authigenic Neodymium Isotope Ratios, Ruifang C. Xie, Franco Marcantonio, Matthew W. Schmidt Jan 2012

Deglacial Variability Of Antarctic Intermediate Water Penetration Into The North Atlantic From Authigenic Neodymium Isotope Ratios, Ruifang C. Xie, Franco Marcantonio, Matthew W. Schmidt

OES Faculty Publications

Understanding intermediate water circulation across the last deglacial is critical in assessing the role of oceanic heat transport associated with Atlantic Meridional Overturning Circulation variability across abrupt climate events. However, the links between intermediate water circulation and abrupt climate events such as the Younger Dryas (YD) and Heinrich Event 1 (H1) are still poorly constrained. Here, we reconstruct changes in Antarctic Intermediate Water (AAIW) circulation in the subtropical North Atlantic over the past 25 kyr by measuring authigenic neodymium isotope ratios in sediments from two sites in the Florida Straits. Our authigenic Nd isotope records suggest that there was little …

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Solar Forcing Of Florida Straits Surface Salinity During The Early Holocene, Matthew W. Schmidt, William A. Weinlein, Franco Marcantonio, Jean Lynch-Stieglitz Jan 2012

Solar Forcing Of Florida Straits Surface Salinity During The Early Holocene, Matthew W. Schmidt, William A. Weinlein, Franco Marcantonio, Jean Lynch-Stieglitz

OES Faculty Publications

Previous studies showed that sea surface salinity (SSS) in the Florida Straits as well as Florida Current transport covaried with changes in North Atlantic climate over the past two millennia. However, little is known about earlier Holocene hydrographic variability in the Florida Straits. Here, we combine Mg/Ca-paleothermometry and stable oxygen isotope measurements on the planktonic foraminifera Globigerinoides ruber (white variety) from Florida Straits sediment core KNR166-2 JPC 51 (24° 24.70' N, 83° 13.14' W, 198 m deep) to reconstruct a high-resolution (~25 yr/sample) early to mid Holocene record of sea surface temperature and δ18OSW)(a …

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Identifying And Tracking Proteins Through The Marine Water Column: Insights Into The Inputs And Preservation Mechanisms Of Protein In Sediments, Eli K. Moore, Brook L. Nunn, David R. Goodlett, H. Rodger Harvey Jan 2012

Identifying And Tracking Proteins Through The Marine Water Column: Insights Into The Inputs And Preservation Mechanisms Of Protein In Sediments, Eli K. Moore, Brook L. Nunn, David R. Goodlett, H. Rodger Harvey

OES Faculty Publications

Proteins generated during primary production represent an important fraction of marine organic nitrogen and carbon, and have the potential to provide organism-specific information in the environment. The Bering Sea is a highly productive system dominated by seasonal blooms and was used as a model system for algal proteins to be tracked through the water column and incorporated into detrital sedimentary material. Samples of suspended and sinking particles were collected at multiple depths along with surface sediments on the continental shelf and deeper basin of the Bering Sea. Modified standard proteomic preparations were used in conjunction with high pressure liquid chromatography-tandem …

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Crowd Documentation: Exploring The Coverage And The Dynamics Of Api Discussions On Stack Overflow, Chris Parnin, Christoph Treude, Lars Grammel, Margaret-Anne Storey Jan 2012

Crowd Documentation: Exploring The Coverage And The Dynamics Of Api Discussions On Stack Overflow, Chris Parnin, Christoph Treude, Lars Grammel, Margaret-Anne Storey

Research Collection School Of Computing and Information Systems

Traditionally, many types of software documentation, such as API documentation, require a process where a few people write for many potential users. The resulting documentation, when it exists, is often of poor quality and lacks sufficient examples and explanations. In this paper, we report on an empirical study to investigate how Question and Answer (Q&A) websites, such as Stack Overflow, facilitate crowd documentation — knowledge that is written by many and read by many. We examine the crowd documentation for three popular APIs: Android, GWT, and the Java programming language. We collect usage data using Google Code Search, and analyze …

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Self-Stabilizing Algorithms For Independence, Domination, And Coloring, Alexander Boris Kunin Jan 2012

Self-Stabilizing Algorithms For Independence, Domination, And Coloring, Alexander Boris Kunin

Theses

Self-stabilization is an algorithmic design paradigm which, since its inception in the early 1970s, has been used to implement efficient solutions that arise in settings where nodes do not have complete knowledge of a network, and more abstractly, to find graph theoretic structures such as independent sets, dominating sets, and spanning trees. This thesis provides a historical overview of the field, as well as a survey of notable papers. In addition to this survey, we provide a simplification of a well-known spanning tree algorithm, and an extension, to provide a proper coloring of bipartite graphs. We also provide a comparison …

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Preliminary Trajectory Analysis Of A Nuclear Fusion Propulsion Fly-By Mission To Saturn And Beyond, Brian Riehm Jan 2012

Preliminary Trajectory Analysis Of A Nuclear Fusion Propulsion Fly-By Mission To Saturn And Beyond, Brian Riehm

Theses

No abstract provided.

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Ferroelectric Capacitance Memory: Characterization Of An Autonous Non-Volatile Ferroelectric Memory Latch, Caroline Sangeetha John Jan 2012

Ferroelectric Capacitance Memory: Characterization Of An Autonous Non-Volatile Ferroelectric Memory Latch, Caroline Sangeetha John

Theses

No abstract provided.

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Effects Of Additives On Rapid Acid/Base Reactions, Gregory Bennett Jan 2012

Effects Of Additives On Rapid Acid/Base Reactions, Gregory Bennett

Theses

No abstract provided.

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Lossy Image Compression Using Wavelet Transform, Huda Al-Ghaib Jan 2012

Lossy Image Compression Using Wavelet Transform, Huda Al-Ghaib

Theses

No abstract provided.

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Number Estimation And Feedback, Lindsey M. Clement Jan 2012

Number Estimation And Feedback, Lindsey M. Clement

Theses

No abstract provided.

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Investigation Of Turbulent Boundary Layer Flow Using A Geometry-Based Artificially Generated Inflow, Man Zhang Jan 2012

Investigation Of Turbulent Boundary Layer Flow Using A Geometry-Based Artificially Generated Inflow, Man Zhang

Theses

No abstract provided.

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Analytical And Numerical Analysis Of Laterally Loaded Pile Group-Cap Foundation System, Srđan Krsto BošKović Jan 2012

Analytical And Numerical Analysis Of Laterally Loaded Pile Group-Cap Foundation System, Srđan Krsto BošKović

Theses

No abstract provided.

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Greedy Routing Via Embedding Graphs Onto Semi-Metric Spaces, Swetha Govindaiah Jan 2012

Greedy Routing Via Embedding Graphs Onto Semi-Metric Spaces, Swetha Govindaiah

Theses

No abstract provided.

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Estimation Of Soil Moisture Profiles From Thermal Infrared Remote Sensing And Application To Agricultural Crop Modeling, Vikalp Mishra Jan 2012

Estimation Of Soil Moisture Profiles From Thermal Infrared Remote Sensing And Application To Agricultural Crop Modeling, Vikalp Mishra

Theses

No abstract provided.

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Optical Analysis Of Microfabricated Glass Cuvettes For Spectroscopic Applications, William R. Gaillard Jan 2012

Optical Analysis Of Microfabricated Glass Cuvettes For Spectroscopic Applications, William R. Gaillard

Theses

No abstract provided.

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Incorporating Input Saturation For Underactuated Surface Vessel Trajectory Tracking Control, Yaswanth Siramdasu Jan 2012

Incorporating Input Saturation For Underactuated Surface Vessel Trajectory Tracking Control, Yaswanth Siramdasu

Theses

No abstract provided.

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Consumer-Driven Innovation Management, Arcot Desai Narasimhalu, Shekhar Mitra Jan 2012

Consumer-Driven Innovation Management, Arcot Desai Narasimhalu, Shekhar Mitra

Research Collection School Of Computing and Information Systems

The evolution of human society leads to increased affluence and prosperity of certain populations, sometimes at the expense of well-established markets. Market leaders in products and services tend to be so focused on their current customer base that they are caught off guard with the changes in markets created by the evolution. These changes often go unnoticed until it is too late. The change in customer base often requires the repositioning of products and services through innovations, which address new and emerging markets. Some of these changes could potentially result in tectonic market shifts that force innovation managers to involve …

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Who Is Retweeting The Tweeters? Modeling, Originating, And Promoting Behaviors In The Twitter Network, Achananuparp Palakorn, Ee Peng Lim, Jing Jiang, Tuan Anh Hoang Jan 2012

Who Is Retweeting The Tweeters? Modeling, Originating, And Promoting Behaviors In The Twitter Network, Achananuparp Palakorn, Ee Peng Lim, Jing Jiang, Tuan Anh Hoang

Research Collection School Of Computing and Information Systems

Real-time microblogging systems such as Twitter offer users an easy and lightweight means to exchange information. Instead of writing formal and lengthy messages, microbloggers prefer to frequently broadcast several short messages to be read by other users. Only when messages are interesting, are they propagated further by the readers. In this article, we examine user behavior relevant to information propagation through microblogging. We specifically use retweeting activities among Twitter users to define and model originating and promoting behavior. We propose a basic model for measuring the two behaviors, a mutual dependency model, which considers the mutual relationships between the two …

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Optimal Decision Making For Online Referral Marketing, Zhiling Guo Jan 2012

Optimal Decision Making For Online Referral Marketing, Zhiling Guo

Research Collection School Of Computing and Information Systems

Widely available web 2.0 technologies not only bring rich and interactive user experiences, but also easily help users advertise products or services on their own blogs and social network webpages. Online referral marketing, for example, is a business practice that rewards customers who successfully refer other customers to a website or upon completion of a sale usually via their own social contacts. The referral rewards come in different forms such as shopping vouchers, redeemable points, discounts, prizes, cash payments, etc. We develop an analytical model to evaluate the business potential of incorporating an online referral marketing program into the firm's …

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A Fuzzy Logic Multi-Criteria Decision Framework For Selecting It Service Providers, Amir Karami, Zhiling Guo Jan 2012

A Fuzzy Logic Multi-Criteria Decision Framework For Selecting It Service Providers, Amir Karami, Zhiling Guo

Research Collection School Of Computing and Information Systems

Selecting IT service providers in information systems outsourcing involves both qualitative and quantitative evaluations. This paper proposes an integrated multi-criteria decision-making (MCDM) framework to effectively handle uncertainty and subjectivity in the vendor selection process. The proposed methods apply fuzzy logic approach to integrate qualitative survey data into traditional multi-criteria decision models such as data envelope analysis (DEA), analytical hierarchy process (AHP) methods, and TOPSIS. Based on case studies from Iranian banking industry, we empirically test the proposed framework and show it is superior to existing methods. We demonstrate that the fuzzy logic approach provides a robust analysis for vendor selection …

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Imbalance Challenge Of Enacting Information Privacy Safeguards In Healthcare: A Grounded Theory Approach, Rachida Parks, Heng Xu, Chao-Hsien Chu Jan 2012

Imbalance Challenge Of Enacting Information Privacy Safeguards In Healthcare: A Grounded Theory Approach, Rachida Parks, Heng Xu, Chao-Hsien Chu

Research Collection School Of Computing and Information Systems

Healthcare organizations face significant challenges in designing and implementing the appropriate safeguards to mitigate information privacy threats. While many studies examined various technical and behavioral safeguards to protect the confidentiality and privacy of patient information, very little is known about the actual outcomes and implications of the privacy practices in which organizations engage. There is little research theoretically explaining the outcomes of enacting privacy safeguards and subsequent effects on privacy compliance. This paper reports the results of a grounded theory study investigating the intended consequences (positive impacts) and unintended (negative impacts) consequences of enacting privacy safeguards in healthcare organizations. An …

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Evaluation Of Disconnected Contributions Using Gpus, C Alexandrou, V Drach, K Hadjiyiannakou, K Jansen, G Koutsou, A Strelchenko, A Vaquero Jan 2012

Evaluation Of Disconnected Contributions Using Gpus, C Alexandrou, V Drach, K Hadjiyiannakou, K Jansen, G Koutsou, A Strelchenko, A Vaquero

School of Engineering, Computing and Mathematics

We calculate on GPUs the disconnected diagrams associated with the nucleon form factors and moments of generalized parton distributions using Nf=2+1+1 twisted mass fermions. We employ the truncated solver method (TSM) for estimating the all-to-all propagators. Due to the fact that the TSM involves many low precision stochastic estimators, the usage of GPUs is essential to perform efficiently the contractions and the inversions.

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