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2007

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Articles 391 - 420 of 5722

Full-Text Articles in Physical Sciences and Mathematics

Bioluminescence In A Complex Coastal Environment: 1. Temporal Dynamics Of Nighttime Water-Leaving Radiance, Mark A. Moline, Matthew J. Oliver, Curtis D. Mobley, Lydia Sundman, Thomas J. Bensky, Trisha Bergmann, W. Paul Bissett, James Case, Erika H. Raymond, Oscar M.E. Schofield Nov 2007

Bioluminescence In A Complex Coastal Environment: 1. Temporal Dynamics Of Nighttime Water-Leaving Radiance, Mark A. Moline, Matthew J. Oliver, Curtis D. Mobley, Lydia Sundman, Thomas J. Bensky, Trisha Bergmann, W. Paul Bissett, James Case, Erika H. Raymond, Oscar M.E. Schofield

Physics

Nighttime water-leaving radiance is a function of the depth-dependent distribution of both the in situ bioluminescence emissions and the absorption and scattering properties of the water. The vertical distributions of these parameters were used as inputs for a modified one-dimensional radiative transfer model to solve for spectral bioluminescence water-leaving radiance from prescribed depths of the water column. Variation in the water-leaving radiance was consistent with local episodic physical forcing events, with tidal forcing, terrestrial runoff, particulate accumulation, and biological responses influencing the shorter timescale dynamics. There was a >90 nm shift in the peak water-leaving radiance from blue (~474 nm) …

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Decomposition Of Regression Estimators To Explore The Influence Of "Unmeasured" Time-Varying Confounders, Yun Lu, Scott L. Zeger Nov 2007

Decomposition Of Regression Estimators To Explore The Influence Of "Unmeasured" Time-Varying Confounders, Yun Lu, Scott L. Zeger

Johns Hopkins University, Dept. of Biostatistics Working Papers

In environmental epidemiology, exposure X and health outcome Y vary in space and time. We present a method to diagnose the possible influence of unmeasured confounders U on the estimated effect of X on Y and to propose several approaches to robust estimation. The idea is to use space and time as proxy measures for the unmeasured factors U. We start with the time series case where X and Y are continuous variables at equally-spaced times and assume a linear model. We define matching estimator b(u)s that correspond to pairs of observations with specific lag u. Controlling for a smooth …

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Microchip Liquid Chromatography And Capillary Electrophoresis Separations In Multilayer Microdevices, Hernan Vicente Fuentes Nov 2007

Microchip Liquid Chromatography And Capillary Electrophoresis Separations In Multilayer Microdevices, Hernan Vicente Fuentes

Theses and Dissertations

In this dissertation, several microfabricated devices are introduced to develop new applications in the area of chemical analysis. Electrochemical micropumps, chip-based liquid chromatography systems and multilayer capillary electrophoresis microdevices with crossover channels were fabricated using various substrates such as poly(dimethylsiloxane) (PDMS), glass, and poly(methyl methacrylate) (PMMA). I have demonstrated pressure-driven pumping of liquids in microfabricated channels using electrochemical actuation. PDMS-based micropumps were integrated easily with channel-containing PMMA substrates. Flow rates on the order of ~10 µL/min were achieved using low voltages (10 V). The potential of electrolysis-based pumping in microchannels was further evaluated for pressure driven microchip liquid chromatography (LC). …

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Matching Kasteleyn Cities For Spin Glass Ground States, Alan Middleton, Creighton K. Thomas Nov 2007

Matching Kasteleyn Cities For Spin Glass Ground States, Alan Middleton, Creighton K. Thomas

Physics - All Scholarship

As spin glass materials have extremely slow dynamics, devious numerical methods are needed to study low-temperature states. A simple and fast optimization version of the classical Kasteleyn treatment of the Ising model is described and applied to two-dimensional Ising spin glasses. The algorithm combines the Pfaffian and matching approaches to directly strip droplet excitations from an excited state. Extended ground states in Ising spin glasses on a torus, which are optimized over all boundary conditions, are used to compute precise values for ground state energy densities.

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Scalable And Adaptive Metadata Management In Ultra Large-Scale File Systems, Yu Hua, Yifeng Zhu, Hong Jiang Nov 2007

Scalable And Adaptive Metadata Management In Ultra Large-Scale File Systems, Yu Hua, Yifeng Zhu, Hong Jiang

School of Computing: Technical Reports

This paper presents a scalable and adaptive decentralized metadata lookup scheme for ultra large-scale file systems (≥ Petabytes or even Exabytes). Our scheme logically organizes metadata servers (MDS) into a multi-layered query hierarchy and exploits grouped Bloom filters to efficiently route metadata requests to desired MDSs through the hierarchy. This metadata lookup scheme can be executed at the network or memory speed, without being bounded by the performance of slow disks. An effective workload balance algorithm is also developed in this paper for server reconfigurations. This scheme is evaluated through extensive trace-driven simulations and prototype implementation in Linux. Experimental results …

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A Delayed Option Pricing Formula (Mittag-Leffler Institute Workshop), Salah-Eldin A. Mohammed Nov 2007

A Delayed Option Pricing Formula (Mittag-Leffler Institute Workshop), Salah-Eldin A. Mohammed

Miscellaneous (presentations, translations, interviews, etc)

No abstract provided.

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Retreating To Advance Women Geoscience Faculty, Suzanne O'Connell, Mary Anne Holmes Nov 2007

Retreating To Advance Women Geoscience Faculty, Suzanne O'Connell, Mary Anne Holmes

Department of Earth and Atmospheric Sciences: Faculty Publications

Seventeen women geoscientists from New England, New York, and New Jersey assembled for a writing retreat at Boston College's Connors Family Retreat and Conference Center, set on 80 pastoral acres on the outskirts of Boston. Funded through the National Science Foundation ADVANCE program, the retreat had two objectives: to facilitate writing and to develop a supportive community. It succeeded on both accounts. Although new to science, retreats of this sort have long been a highly sought after experience for writers in other disciplines. The potential benefits for scientists, in particular, women scientists, are great. Writing is a cornerstone of our …

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Supporting Annotated Relations, M. Y. Eltabakh, M. Ouzzani, Walid G. Aref, Ahmed K. Elmagarmid, Y. Laura-Silva Nov 2007

Supporting Annotated Relations, M. Y. Eltabakh, M. Ouzzani, Walid G. Aref, Ahmed K. Elmagarmid, Y. Laura-Silva

Department of Computer Science Technical Reports

No abstract provided.

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Measurement Of The Tt̅ Production Cross Section In Pp̅ Collisions At √S = 1.96 Tev Using Kinematic Characteristics Of Lepton + Jets Events, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration Nov 2007

Measurement Of The Tt̅ Production Cross Section In Pp̅ Collisions At √S = 1.96 Tev Using Kinematic Characteristics Of Lepton + Jets Events, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We present a measurement of the top quark pair production cross section in pp̅ collisions at √s = 1.96 TeV utilizing 425 pb-1 of data collected with the D0 detector at the Fermilab Tevatron Collider. We consider the final state of the top quark pair containing one high-pT electron or muon and at least four jets. We exploit specific kinematic features of tt̅ events to extract the cross section. For a top quark mass of 175 GeV, we measure σ tt̅ = 6.4-1.2+1.3(stat) ± 0.7(syst) ± 0.4(lum) pb, in good agreement with the …

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Effects Of Dependency Injection On Maintainability, Ekaterina Razina, David S. Janzen Nov 2007

Effects Of Dependency Injection On Maintainability, Ekaterina Razina, David S. Janzen

Computer Science and Software Engineering

Software maintenance consumes around 70% of the software life cycle. Improving software maintainability could save software developers significant time and money. This paper examines whether the pattern of dependency injection significantly reduces dependencies of modules in a piece of software, therefore making the software more maintainable. This hypothesis is tested with 20 sets of open source projects from sourceforge.net, where each set contains one project that uses the pattern of dependency injection and one similar project that does not use the pattern. The extent of the dependency injection use in each project is measured by a new Number of DIs …

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A Set Of Phosphatase-Inert “Molecular Rulers” To Probe For Bivalent Mannose 6-Phosphate Ligand-Receptor Interactions, Xiang Fei, Christopher M. Connelly, Richard G. Macdonald, David B. Berkowitz Nov 2007

A Set Of Phosphatase-Inert “Molecular Rulers” To Probe For Bivalent Mannose 6-Phosphate Ligand-Receptor Interactions, Xiang Fei, Christopher M. Connelly, Richard G. Macdonald, David B. Berkowitz

David Berkowitz Publications

A set of bivalent mannose 6-phosphonate “molecular rulers” has been synthesized to examine ligand binding to the M6P/IGF2R. The set is estimated to span a P-P distance range of 16-26 Å (MMFF energy minimization on the hydrated phosphonates). Key synthetic transformations include sugar triflate displacement for phosphonate installation and Grubbs I cross-metathesis to achieve bivalency. Relative binding affinities were tested by radioligand displacement assays versus PMP-BSA (pentamannose phosphate-bovine serum albumin). These compounds exhibit slightly higher binding affinities for the receptor (IC50’s = 3.7-5 &#;M) than the parent, monomeric mannose 6-phosphonate ligand and M6P itself (IC50 = 11.5 …

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Microfluidic Electro-Osmotic Flow Pumps, John Mason Edwards Nov 2007

Microfluidic Electro-Osmotic Flow Pumps, John Mason Edwards

Theses and Dissertations

The need for miniaturized, portable devices to separate and detect unknown compounds has greatly multiplied, leading to an increased interest in microfluidics. Total integration of the detector and pump are necessary to decrease the overall size of the microfluidic device. Using previously developed thin film technologies, an electroosmotic flow (EOF) pump was incorporated in a microfluidic liquid chromatography device. An EOF pump was chosen because of its simple design and small size. EOF pumps fabricated on silicon and glass substrates were evaluated. The experimental flow rates were 0.19-2.30 microliters/minute for 40-400 V. The theoretical pump efficiency was calculated along with …

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Supporting Views In Data Stream Management System, Thanaa M. Ghanem, Walid G. Aref, Ahmed K. Elmagarmid, Per-Ake Larson Nov 2007

Supporting Views In Data Stream Management System, Thanaa M. Ghanem, Walid G. Aref, Ahmed K. Elmagarmid, Per-Ake Larson

Department of Computer Science Technical Reports

No abstract provided.

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An Architectural Approach To Improving The Availability Of Parity-Based Raid Systems, Lei Tian, Hong Jiang, Dan Feng, Qin Xin, Sai Huang Nov 2007

An Architectural Approach To Improving The Availability Of Parity-Based Raid Systems, Lei Tian, Hong Jiang, Dan Feng, Qin Xin, Sai Huang

School of Computing: Technical Reports

In this paper, we propose an architectural approach, Supplementary Partial Parity (SPP), to addressing the availability issue of parity encoded RAID systems. SPP exploits free storage space and idle time to generate and update a set of partial parity units that cover a subset of disks (or data stripe units) during failure-free and idle/lightly-loaded periods, thus supplementing the existing full parity units for improved availability. By applying the exclusive OR operations appropriately among partial parity, full parity and data units, SPP can reconstruct the data on the failed disks with a fraction of the original overhead that is proportional to …

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Amp: An Affinity-Based Metadata Prefetching Scheme In Large-Scale Distributed Storage Systems, Lin Li, Xuemin Li, Hong Jiang, Yifeng Zhu Nov 2007

Amp: An Affinity-Based Metadata Prefetching Scheme In Large-Scale Distributed Storage Systems, Lin Li, Xuemin Li, Hong Jiang, Yifeng Zhu

School of Computing: Technical Reports

Prefetching is an effective technique for improving file access performance, which can reduce access latency for I/O systems. In distributed storage system, prefetching for metadata files is critical for the overall system performance. In this paper, an Affinity-based Metadata Prefetching (APM) scheme is proposed for metadata servers in large-scale distributed storage systems to provide aggressive metadata prefetching. Through mining useful information about metadata assesses from past history, AMP can discover metadata file affinities accurately and intelligently for prefetching. Compared with LRU and some of the latest file prefetching algorithms such as NEXUS and C-miner, trace-driven simulations show that AMP can …

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An Approach To Mapping Of Shallow Petroleum Reservoirs Using Integrated Conventional 3d And Shallow P- And Sh-Wave Seismic Reflection Methods At Teapot Dome Field In Casper, Wyoming, Anita Onohuome Okojie-Ayoro Nov 2007

An Approach To Mapping Of Shallow Petroleum Reservoirs Using Integrated Conventional 3d And Shallow P- And Sh-Wave Seismic Reflection Methods At Teapot Dome Field In Casper, Wyoming, Anita Onohuome Okojie-Ayoro

Theses and Dissertations

Using the famous Teapot Dome oil field in Casper, Wyoming, USA as a test case, we demonstrate how high-resolution compressional (P) and horizontally polarized shear (SH) wave seismic reflection surveys can overcome the limitations of conventional 3D seismic data in resolving small-scale structures in the very shallow subsurface (< 100-200 m (~328-656 ft)). We accomplish this by using small CMP intervals (5 ft and 2.5 ft, respectively) and a higher frequency source. The integration of the two high-resolution seismic methods enhances the detection and mapping of fine-scale deformation and stratigraphic features at shallow depth that cannot be imaged by conventional seismic methods. Further, when these two high-resolution seismic methods are integrated with 3D data, correlated drill hole logs, and outcrop mapping and trenching, a clearer picture of both very shallow reservoirs and the relationship between deep and shallow faults can be observed. For example, we show that the Shannon reservoir, which is the shallowest petroleum reservoir at Teapot Dome (depth to the top of this interval ranging from 76-198 m (250-650 ft)) can only be imaged properly with high-resolution seismic methods. Further, northeast-striking faults are identified in shallow sections within Teapot Dome. The strike of these faults is approximately orthogonal to the hinge of Teapot Dome. These faults are interpreted as fold accommodation faults. Vertical displacements across these faults range from 10 to 40 m (~33 to 131 ft), which could potentially partition the Shannon reservoir. The integration of 3D and high-resolution P-wave seismic interpretation helped us determine that some of the northeast-striking faults relate to deeper faults. This indicates that some deeper faults that are orthogonal to the fold hinge cut through the shallow Shannon reservoir. Such an observation would be important for understanding the effect on fluid communication between the deep and shallow reservoirs via these faults. Furthermore, the high-resolution seismic data provide a means to better constrain the location of faults mapped from drill hole logs. Relocation of theses faults may require re-evaluation of well locations as some attic oil may have not been drained in some Shannon blocks by present well locations. Therefore our study demonstrates how conventional 3D seismic data require additional seismic acquisition at smaller scales in order to image deformation in shallow reservoirs. Such imaging becomes critical in cases of shallow reservoirs where it is important to define potential problems associated with compartmentalization of primary production, hazard mitigation, enhanced oil recovery, or carbon sequestration.

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Modeling T Tauri Winds From He I Λ10830 Profiles, John Kwan, Suzan Edwards, William Fischer Nov 2007

Modeling T Tauri Winds From He I Λ10830 Profiles, John Kwan, Suzan Edwards, William Fischer

Astronomy: Faculty Publications

The high opacity of He I λ10830 makes it an exceptionally sensitive probe of the inner wind geometry of accreting T Tauri stars. In this line, blueshifted absorption below the continuum results from simple scattering of stellar photons, a situation that is readily modeled without definite knowledge of the physical conditions and recourse to multilevel radiative transfer. We present theoretical line profiles for scattering in two possible wind geometries, a disk wind and a wind emerging radially from the star, and compare them to observed He I λ10830 profiles from a survey of classical T Tauri stars. The comparison indicates …

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A Summer Time Series Of Particulate Carbon In The Air And Snow At Summit, Greenland, Gayle S.W. Hagler, M Bergin, Eugene A. Smith, Jack E. Dibb Nov 2007

A Summer Time Series Of Particulate Carbon In The Air And Snow At Summit, Greenland, Gayle S.W. Hagler, M Bergin, Eugene A. Smith, Jack E. Dibb

Earth Sciences

Carbonaceous particulate matter is ubiquitous in the lower atmosphere, produced by natural and anthropogenic sources and transported to distant regions, including the pristine and climate-sensitive Greenland Ice Sheet. During the summer of 2006, ambient particulate carbonaceous compounds were characterized on the Greenland Ice Sheet, including the measurement of particulate organic (OC) and elemental (EC) carbon, particulate water-soluble organic carbon (WSOC), particulate absorption coefficient (σap), and particle size-resolved number concentration (PM0.1–1.0). Additionally, parallel ∼50-day time series of water-soluble organic carbon (WSOC), water-insoluble organic carbon (WIOC), and elemental carbon (EC) were quantified at time increments of 4–24 …

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Energy-Constrained Recharge, Assimilation, And Fractional Crystallization (Ec-Raxfc): A Visual Basic Computer Code For Calculating Trace Element And Isotope Variations Of Opensystem Magmatic Systems, Wendy A. Bohrson, Frank J. Spera Nov 2007

Energy-Constrained Recharge, Assimilation, And Fractional Crystallization (Ec-Raxfc): A Visual Basic Computer Code For Calculating Trace Element And Isotope Variations Of Opensystem Magmatic Systems, Wendy A. Bohrson, Frank J. Spera

All Faculty Scholarship for the College of the Sciences

Volcanic and plutonic rocks provide abundant evidence for complex processes that occur in magma storage and transport systems. The fingerprint of these processes, which include fractional crystallization, assimilation, and magma recharge, is captured in petrologic and geochemical characteristics of suites of cogenetic rocks. Quantitatively evaluating the relative contributions of each process requires integration of mass, species, and energy constraints, applied in a self-consistent way. The energy-constrained model Energy-Constrained Recharge, Assimilation, and Fractional Crystallization (EC-RaxFC) tracks the trace element and isotopic evolution of a magmatic system (melt + solids) undergoing simultaneous fractional crystallization, recharge, and assimilation. Mass, thermal, and compositional (trace …

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Supercurrent Survival Under A Rosen-Zener Quench Of Hard-Core Bosons, I. Klich, Courtney Lannert, G. Refael Nov 2007

Supercurrent Survival Under A Rosen-Zener Quench Of Hard-Core Bosons, I. Klich, Courtney Lannert, G. Refael

Physics: Faculty Publications

We study the survival of supercurrents in a system of impenetrable bosons on a lattice, subject to a quantum quench from its critical superfluid phase to an insulating phase. We show that the evolution of the current when the quench follows a Rosen-Zener profile is exactly solvable. This allows us to analyze a quench of arbitrary rate, from a sudden destruction of the superfluid to a slow opening of a gap. The decay and oscillations of the current are analytically derived and studied numerically along with the momentum distribution after the quench. In the case of small supercurrent boosts ν, …

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Supporting Flight Control For Uav-Assisted Wilderness Search And Rescue Through Human Centered Interface Design, Joseph L. Cooper Nov 2007

Supporting Flight Control For Uav-Assisted Wilderness Search And Rescue Through Human Centered Interface Design, Joseph L. Cooper

Theses and Dissertations

Inexpensive, rapidly deployable, camera-equipped Unmanned Aerial Vehicle (UAV) systems can potentially assist with a huge number of tasks. However, in many cases such as wilderness search and rescue (WiSAR), the potential users of the system may not be trained as pilots. Simple interface concepts can be used to build an interaction layer that allows an individual with minimal operator training to use the system to facilitate a search or inspection task. We describe an analysis of WiSAR as currently accomplished and show how a UAV system might fit into the existing structure. We then discuss preliminary system design efforts for …

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Fish Nutrient Cycling, Aquatic Respiration, And Terrestrial Insect Nutrient Subsidies To Lakes, Wayne A. Wurtsbaugh Nov 2007

Fish Nutrient Cycling, Aquatic Respiration, And Terrestrial Insect Nutrient Subsidies To Lakes, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

Mehner et al. (2005) reported that fish feeding on terrestrial insects could be important for nutrient budgets and cycling in lakes. They studied bleak (Alburnus alburnus) that fed largely on terrestrial insects, and they suggested that this contributed 2.1% of the lake's nutrient budget and that the subsequent excretion by the fish was equivalent to 11% of epilimnetic dissolved phosphorus concentrations. They concluded that nutrients delivered to lakes via terrestrial insects and recycled by fish would be most important for small lakes because of the large perimeter-to-area ratio between donor and recipient habitats. Fish may have important impacts …

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Relationship Between Vegetation Biophysical Properties And Surface Temperature Using Multisensor Satellite Data, Seungbum Hong, Venkataraman Lakshmi, Eric Small Nov 2007

Relationship Between Vegetation Biophysical Properties And Surface Temperature Using Multisensor Satellite Data, Seungbum Hong, Venkataraman Lakshmi, Eric Small

Faculty Publications

Vegetation is an important factor in global climatic variability and plays a key role in the complexinteractions between the land surface and the atmosphere. This study focuses on the spatial and temporalvariability of vegetation and its relationship with land–atmosphere interactions. The authors have analyzedthe vegetation water content (VegWC) from the Advanced Microwave Scanning Radiometer for EOS(AMSR-E), the leaf area index (LAI), the normalized difference vegetation index (NDVI), the land surfacetemperature (Ts), and the Moderate Resolution Imaging Spectroradiometer (MODIS). Three regions,which have climatically differing characteristics, have been selected: the North America Monsoon System(NAMS) region, the Southern Great Plains (SGP) region, and …

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Myricetin Inhibits Escherichia Coli Dnab Helicase But Not Primase, Mark A. Griep, Sheldon Blood, Marilynn A. Larson, Scott A. Koepsell, Steven H. Hinrichs Nov 2007

Myricetin Inhibits Escherichia Coli Dnab Helicase But Not Primase, Mark A. Griep, Sheldon Blood, Marilynn A. Larson, Scott A. Koepsell, Steven H. Hinrichs

Mark A. Griep Publications

Primase and DnaB helicase play central roles during DNA replication initiation and elongation. Both enzymes are drug targets because they are essential, persistent among bacterial genomes, and have different sequences than their eukaryotic equivalents. Myricetin is a ubiquitous natural product in plants that is known to inhibit a variety of DNA polymerases, RNA polymerases, reverse transcriptases, and telomerases in addition being able to inhibit kinases and helicases. We have shown that myricetin inhibits Escherichia coli DnaB helicase according to a mechanism dominated by noncompetitive behavior with a Ki of 10.0 ± 0.5 μM. At physiological ATP concentration, myricetin inhibits …

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Scalar Mesons From An Effective Lagrangian Approach, Joseph Schechter, Amir H. Fariborz, Renata Jora Nov 2007

Scalar Mesons From An Effective Lagrangian Approach, Joseph Schechter, Amir H. Fariborz, Renata Jora

Physics - All Scholarship

A brief discussion of the recent interest in light scalar mesons motivates the study of a generalized linear sigma model. In an SU(3) flavor invariant version of the model there is a prediction that the the lighter scalars have sizeable "four quark" content. It is further predicted that one of the singlet scalars should be exceptionally light. Due to the presence of scalar mesons, the model gives "controlled" corrections to the current algebra formula for threshold pion pion scattering. These corections act in the direction to improve agreement with current experiments.

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A Parametric Roc Model Based Approach For Evaluating The Predictiveness Of Continuous Markers In Case-Control Studies, Ying Huang, Margaret Pepe Nov 2007

A Parametric Roc Model Based Approach For Evaluating The Predictiveness Of Continuous Markers In Case-Control Studies, Ying Huang, Margaret Pepe

UW Biostatistics Working Paper Series

The predictiveness curve shows the population distribution of risk endowed by a marker or risk prediction model. It provides a means for assessing the model's capacity for risk stratification. Methods for making inference about the predictiveness curve have been developed using cross-sectional or cohort data. Here we consider inference based on case-control studies and prior knowledge about prevalence or incidence of the outcome. We exploit the relationship between the ROC curve and the predictiveness curve given disease prevalence. Methods are developed for deriving the predictiveness curve from a parametric ROC model. Estimation of the whole range and of a portion …

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A Delayed Option Pricing Formula (University Of Manchester Probability Seminar), Salah-Eldin A. Mohammed Nov 2007

A Delayed Option Pricing Formula (University Of Manchester Probability Seminar), Salah-Eldin A. Mohammed

Miscellaneous (presentations, translations, interviews, etc)

No abstract provided.

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Counter-Flow Ion Mobility Analysis: Design, Instrumentation, And Characterization, Nosa Agbonkonkon Nov 2007

Counter-Flow Ion Mobility Analysis: Design, Instrumentation, And Characterization, Nosa Agbonkonkon

Theses and Dissertations

The quest to achieve high resolution in ion mobility spectrometry (IMS) has continued to challenge scientist and engineers in the field of separation science. The low resolution presently attainable in IMS has continued to negatively impact its utility and acceptance. Until now, efforts to improve the resolution have mainly focused on better instrumentation and detection methods. However, since the resolution of IMS is diffusion limited, it makes sense to address this limitation in order to attain high resolution. This dissertation presents a new IMS technique, which utilizes a high electric field and opposing high gas flow velocity with the aim …

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Leveraging Semantic Web Techniques To Gain Situational Awareness, Amit P. Sheth Nov 2007

Leveraging Semantic Web Techniques To Gain Situational Awareness, Amit P. Sheth

Kno.e.sis Publications

No abstract provided.

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Real Space Information From Fluctuation Electron Microscopy: Applications To Amorphous Silicon, Parthapratim Biswas, Raymond Atta-Fynn, S. Chakraborty, D. A. Drabold Nov 2007

Real Space Information From Fluctuation Electron Microscopy: Applications To Amorphous Silicon, Parthapratim Biswas, Raymond Atta-Fynn, S. Chakraborty, D. A. Drabold

Faculty Publications

Ideal models of complex materials must satisfy all available information about the system. Generally, this information consists of experimental data, information implicit to sophisticated interatomic interactions and potentially other a priori information. By jointly imposing first-principles or tight-binding information in conjunction with experimental data, we have developed a method: experimentally constrained molecular relaxation (ECMR) that uses all of the information available. We apply the method to model medium range order in amorphous silicon using fluctuation electron microscopy (FEM) data as experimental information. The paracrystalline model of medium range order is examined, and a new model based on voids in amorphous …

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