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2009

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Articles 4141 - 4170 of 7616

Full-Text Articles in Physical Sciences and Mathematics

Macroporous Silica Using A “Sticky” Stöber Process, Rebecca Cademartiri, Michael A. Brook, Robert Pelton, John D. Brennan Jan 2009

Macroporous Silica Using A “Sticky” Stöber Process, Rebecca Cademartiri, Michael A. Brook, Robert Pelton, John D. Brennan

Rebecca Cademartiri

The generation of macroporous silica structures using a sol–gel process generally requires the presence of high molecular weight, water-soluble polymers. We demonstrate that significantly lower molecular weight poly(ethylene glycol) (PEG) polymers can drive a particle aggregation process to generate macroporous silica. Compared to unfunctionalized PEGs (HO–PEG–HO, molecular weight > 10 000 g mol−1), PEG polymers with allyl (A–PEG–A) or silyl end groups (CH2)3Si(OEt)3 (Si–PEG–Si), with molecular weights of 2000 g mol−1 or greater, lead to monolithic macroporous structures derived from aggregates of nearly monodisperse particles. Lower molecular weight (less than 1000 g mol−1) allyl or silyl PEG, or hydroxy-terminated PEG–OH, lead …

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One Rna Plays Three Roles To Provide Catalytic Activity To A Group I Intron Lacking An Endogenous Internal Guide Sequence, Nilesh Vaidya, Niles Lehman Jan 2009

One Rna Plays Three Roles To Provide Catalytic Activity To A Group I Intron Lacking An Endogenous Internal Guide Sequence, Nilesh Vaidya, Niles Lehman

Chemistry Faculty Publications and Presentations

Catalytic RNA molecules possess simultaneously a genotype and a phenotype. However, a single RNA genotype has the potential to adopt two or perhaps more distinct phenotypes as a result of differential folding and/or catalytic activity. Such multifunctionality would be particularly significant if the phenotypes were functionally inter-related in a common biochemical pathway. Here, this phenomenon is demonstrated by the ability of the Azoarcus group I ribozyme to function when its canonical internal guide sequence (GUG) has been removed from the 5? end of the molecule, and added back exogenously in trans. The presence of GUG triplets in noncovalent fragments of …

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Gravitational Redshift And Deflection Of Slow Light, Justin Dressel, S. G. Rajeev, J. C. Howell, Andrew N. Jordan Jan 2009

Gravitational Redshift And Deflection Of Slow Light, Justin Dressel, S. G. Rajeev, J. C. Howell, Andrew N. Jordan

Mathematics, Physics, and Computer Science Faculty Articles and Research

We explore the nature of the classical propagation of light through media with strong frequency-dependent dispersion in the presence of a gravitational field. In the weak field limit, gravity causes a redshift of the optical frequency, which the slow-light medium converts into a spatially varying index of refraction. This results in the bending of a light ray in the medium. We further propose experimental techniques to amplify and detect the phenomenon using weak value measurements. Independent heuristic and rigorous derivations of this effect are given.

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The Role Of Water And Other Resources In The Invasion Of Rubus Armeniacus In Pacific Northwest Ecosystems, Joshua Sundance Caplan Jan 2009

The Role Of Water And Other Resources In The Invasion Of Rubus Armeniacus In Pacific Northwest Ecosystems, Joshua Sundance Caplan

Dissertations and Theses

The factors influencing the invasive success of Rubus armeniacus (Himalayan blackberry) in the Pacific Northwest of North America are only partly understood, but have important implications for its management and for our understanding of the processes driving invasive plant proliferation in regions with seasonally fluctuating resources. I identified patterns of R. armeniacus occurrence and growth under widely ranging soil and light conditions in western Oregon. I found that light availability was a primary determinant of R. armeniacus occurrence and growth. I also found that R. armeniacus was tolerant of a wide range of soil conditions, notably coarse texture, and could …

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Enhancing The Multicast Performance Of Structured P2p Overlay In Supporting Massively Multiplayer Online Games, Xinbo Jiang, Farzad Safaei, P. Boustead Jan 2009

Enhancing The Multicast Performance Of Structured P2p Overlay In Supporting Massively Multiplayer Online Games, Xinbo Jiang, Farzad Safaei, P. Boustead

Paul Boustead

Scribe is a scalable application level multicast infrastructure. We have developed two techniques to improve the performance of Scribe in terms of latency and bandwidth distribution. The first technique identifies that the final hop of Scribe traffic path is largely selected without any proximity consideration and incurs the longest distance traveled. To overcome this, we introduce Proximity Neighbor Selection (PNS) into the final hop for latency improvement. The second technique builds a hierarchical two-level overlay. While PNS can be applied at both levels for latency performance, the bandwidth stress required by applications can now be distributed among the nodes in …

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Sla Automated Negotiation Manager For Computing Services, Halina Kaminski, Mark Perry Jan 2009

Sla Automated Negotiation Manager For Computing Services, Halina Kaminski, Mark Perry

Mark Perry

Success in today’s marketing arena can often depend on companies embracing effective new technologies and integrating them into their business model. In the computing service supply industry, Service Level Agreements (SLAs) are commonly prepared and signed agreements between the service provider and its customers. SLAs should match business needs of both sides of the agreement as closely as possible. This paper focuses on at the steps and activities that the service provider can take to facilitate agreement. It proposes an automated way for creating SLA’s from a set of Service Level Objectives (SLOs). The SLA should achieve business goals, including …

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Policies, Rules And Their Engines: What Do They Mean For Slas?, Mark Perry, Michael Bauer Jan 2009

Policies, Rules And Their Engines: What Do They Mean For Slas?, Mark Perry, Michael Bauer

Mark Perry

In our model for autonomic management of service level agreements (SLA), the roles played by policy and rules must be clearly differentiated. Although policy is typically an ideal we wish to achieve through the implementation of rules, the use of the terms policy and rule are often treated similarly and that consequently policy-engine and rule-engine are often used synonymously. It is our position that in the management of SLAs these terms have specific meanings. The definitions and models embodied are illustrated.

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Differentiating Web Service Offerings, Halina Kaminski, Khalid Sherdil, Hanan Lutfiyya, Nazim Madhavji, Mark Perry Jan 2009

Differentiating Web Service Offerings, Halina Kaminski, Khalid Sherdil, Hanan Lutfiyya, Nazim Madhavji, Mark Perry

Mark Perry

The advent of Service Oriented Architecture (SOA) paradigm and increasing use of Web Services (WS) implies that the future will see a large number of services transferred between providers and consumers, using many applications or agents working on behalf of humans. Discovering and using the services is the easy part. Negotiating and selecting the best services from amongst the plethora of similar ones, depending on their cost and quality, is the challenging issue. However, existing WS-I standards neither cater to provision of Service Level Agreements (SLAs), nor their exchange between parties. These standards are confined merely to WS description (WSDL). …

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Verifiable Electronic Voting System: An Open Source Solution, Halina Kaminski, Mark Perry Jan 2009

Verifiable Electronic Voting System: An Open Source Solution, Halina Kaminski, Mark Perry

Mark Perry

Elections, referenda and polls are vital processes for the operation of a modern democracy. They form the mechanism for transferring power from citizens to their representatives. Although some commentators claim that the pencil-and-paper systems used in countries such as Canada and UK are still the best method of avoiding voterigging, recent election problems, and the need for faster, better, cheaper vote counting, have stimulated great interest in managing the election process through the use of electronic voting systems. While computer scientists, for the most part, have been warning of the possible perils of such action, vendors have forged ahead with …

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Who Counts Your Votes?, Halina Kaminski, Lila Kari, Mark Perry Jan 2009

Who Counts Your Votes?, Halina Kaminski, Lila Kari, Mark Perry

Mark Perry

Open and fair elections are paramount to modern democracy. Although some people claim that the penciland- paper systems used in countries such as Canada and UK are still the best method of avoiding vote rigging, recent election problems have sparked great interest in managing the election process through the use of electronic voting systems. It is a goal of this paper to describe a voting system that is secret and secure as well as verifiable and useable over an existing computer network. We have designed and implemented an electronic voting system – Verifiable E-Voting (VEV) – with an underlying protocol …

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Open Source Software Licensing Patterns, Halina Kaminski, Mark Perry Jan 2009

Open Source Software Licensing Patterns, Halina Kaminski, Mark Perry

Mark Perry

No abstract provided.

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Quantifying Uncertainty In Genotype Calls, Benilton Carvalho, Thomas A. Louis, Rafael A. Irizarry Jan 2009

Quantifying Uncertainty In Genotype Calls, Benilton Carvalho, Thomas A. Louis, Rafael A. Irizarry

Johns Hopkins University, Dept. of Biostatistics Working Papers

Genome-wide association studies (GWAS) are used to discover genes underlying complex, heritable disorders for which less powerful study designs have failed in the past. The number of GWAS has skyrocketed recently with findings reported in top journals and the mainstream media. Mircorarrays are the genotype calling technology of choice in GWAS as they permit exploration of more than a million single nucleotide polymorphisms (SNPs)simultaneously. The starting point for the statistical analyses used by GWAS, to determine association between loci and disease, are genotype calls (AA, AB, or BB). However, the raw data, microarray probe intensities, are heavily processed before arriving …

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Sparse Linear Discriminant Analysis For Simultaneous Testing For The Significance Of A Gene Set/Pathway And Gene Selection, Michael C. Wu, Lingson Zhang, Zhaoxi Wang, David C. Christiani, Xihong Lin Jan 2009

Sparse Linear Discriminant Analysis For Simultaneous Testing For The Significance Of A Gene Set/Pathway And Gene Selection, Michael C. Wu, Lingson Zhang, Zhaoxi Wang, David C. Christiani, Xihong Lin

Harvard University Biostatistics Working Paper Series

No abstract provided.

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Investigating The Tev Morphology Of Mgro J1908+06 With Veritas, P. T. Reynolds, Et. Al. Jan 2009

Investigating The Tev Morphology Of Mgro J1908+06 With Veritas, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We report on deep observations of the extended TeV gamma-ray source MGRO J1908+06 made with the VERITAS very high energy gamma-ray observatory. Previously, the TeV emission has been attributed to the pulsar wind nebula (PWN) of the Fermi-LAT pulsar PSR J1907+0602. We detect MGRO J1908+06 at a significance level of 14 standard deviations (14σ) and measure a photon index of 2.20 ± 0.10stat ± 0.20sys. The TeV emission is extended, covering the region near PSR J1907+0602 and also extending toward SNR G40.5-0.5. When fitted with a two-dimensional Gaussian, the intrinsic extension has a standard deviation of σsrc = 0fdg44 ± …

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York River Water Budget, Carl Hershner, Molly Mitchell, Donna Marie Bilkovic, Julie D. Herman, Center For Coastal Resources Management, Virginia Institute Of Marine Science Jan 2009

York River Water Budget, Carl Hershner, Molly Mitchell, Donna Marie Bilkovic, Julie D. Herman, Center For Coastal Resources Management, Virginia Institute Of Marine Science

Reports

No abstract provided.

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Guessing Harmonic Oscillator Wavefunctions Using Maple, Carl W. David Jan 2009

Guessing Harmonic Oscillator Wavefunctions Using Maple, Carl W. David

Chemistry Education Materials

The guessing of eigenfunctions is not trivial at higher quantum numbers, no matter what the system being considered. Instead of guessing, one can employ a symbolic calculus progam (Maple in this case) to aid in the reasoning process.

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The Driven Harmonic Oscillator In Chemistry, Carl W. David Jan 2009

The Driven Harmonic Oscillator In Chemistry, Carl W. David

Chemistry Education Materials

The molecular dynamical simulation of the normal vibrational mode of water which involves H-O-H angle deformation, when driven by an external force, can be used to see how a driven harmonic oscillator, classically, is associated with the infra-red spectrum of water (and the absorption for this particular normal mode).

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Highly Connected Random Geometric Graphs, Paul Balister, Béla Bollobás, Amites Sarkar, Mark Walters Jan 2009

Highly Connected Random Geometric Graphs, Paul Balister, Béla Bollobás, Amites Sarkar, Mark Walters

Mathematics Faculty Publications

Let P be a Poisson process of intensity 1 in a square Sn of area n. We construct a random geometric graph Gn,k by joining each point of P to its k nearest neighbours. For many applications it is desirable that Gn,k is highly connected, that is, it remains connected even after the removal of a small number of its vertices. In this paper we relate the study of the s-connectivity of Gn,k to our previous work on the connectivity of Gn,k. Roughly speaking, we show that for s=o(logn), the threshold (in k) for …

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Spectropolarimetric Variability And Co-Rotating Structure In Hd 92207., Richard Ignace, S. Hubrig, M. Schöller Jan 2009

Spectropolarimetric Variability And Co-Rotating Structure In Hd 92207., Richard Ignace, S. Hubrig, M. Schöller

ETSU Faculty Works

We report on low resolution (R~3000) spectropolarimetry of the A0 supergiant star HD 92207. This star is well-known for significant spectral variability. The source was observed on seven different nights spanning approximately 3 months in time. With a rotation period of approximately 1 year, our data covers approximately a quarter of the star's rotational phase. Variability in the continuum polarization level is observed over this period of time. The polarization across the Halpha line on any given night is typically different from the degree and position angle of the polarization in the continuum. Interestingly, Hbeta is not in emission and …

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Innovation Imitation And North South Trade: Economic Theory And Policy., Debasis Mondal Dr. Jan 2009

Innovation Imitation And North South Trade: Economic Theory And Policy., Debasis Mondal Dr.

Doctoral Theses

No abstract provided.

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Spectropolarimetric Variability And Co-Rotating Structure In Hd 92207., Richard Ignace, S. Hubrig, M. Schöller Jan 2009

Spectropolarimetric Variability And Co-Rotating Structure In Hd 92207., Richard Ignace, S. Hubrig, M. Schöller

Richard Ignace

We report on low resolution (R~3000) spectropolarimetry of the A0 supergiant star HD 92207. This star is well-known for significant spectral variability. The source was observed on seven different nights spanning approximately 3 months in time. With a rotation period of approximately 1 year, our data covers approximately a quarter of the star's rotational phase. Variability in the continuum polarization level is observed over this period of time. The polarization across the Halpha line on any given night is typically different from the degree and position angle of the polarization in the continuum. Interestingly, Hbeta is not in emission and …

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Evaluation Of Biofuel Driven Irrigation Pumps And/Or Electric Generators For Use During Peak Electricity Demand, Milford Hanna Jan 2009

Evaluation Of Biofuel Driven Irrigation Pumps And/Or Electric Generators For Use During Peak Electricity Demand, Milford Hanna

Nebraska Center for Energy Sciences Research: White Papers and Presentations

The goal of this research is to support the development of a biofuel power unit industry in Nebraska to increase the use of agricultural resources, crops and the resulting biofuels that are produced in the region. Two Nebraska companies developed commercially available technologies to utilize denatured ethanol and other biofuels in industrial power‐units. The successful validation and demonstration of these technologies will support adaptation in water pumping and electrical generation plant applications. It will also document exhaust emissions and compare operating cost with traditional engines and fuels. These technologies could reduce peak load electrical energy demand resulting from electrical powered …

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Water, Energy And Agriculture Initiative Jan 2009

Water, Energy And Agriculture Initiative

Nebraska Center for Energy Sciences Research: White Papers and Presentations

Rapid expansion of the biofuel industry provides exciting opportunities for economic growth and development in rural Nebraska. Realizing the full benefits of this opportunity and ensuring its long‐term viability depends on continued access to adequate supplies of water, electrical energy, and biofuel feedstock crops at reasonable cost. For example, about 70 percent of all corn and 50 percent of soybeans produced in Nebraska comes from irrigated land, and electrical energy for pumping irrigation water represents a major component of peak‐load energy demand in the state. Reducing this peak‐load electrical demand and consumption is essential for reducing the need for new …

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Optimization Of Irrigation Efficiency Of Center‐Pivot Systems Using Spatial And Temporal Data Integration, Viacheslav Adamchuk Jan 2009

Optimization Of Irrigation Efficiency Of Center‐Pivot Systems Using Spatial And Temporal Data Integration, Viacheslav Adamchuk

Nebraska Center for Energy Sciences Research: White Papers and Presentations

The efficiency of a center pivot irrigation system is greatly dependent on the ability to provide the water supply needed to meet the demands of the rowing crop. While limited water supplies may educe crop yield due to water stress, excessive irrigation may result in wasted resources and, if extreme, may also reduce yields. The optimized need for irrigation water changes temporally and spatially. Various methods have been deployed to focus on either level of variability. Thus, soil sensor telemetry and crop modeling frequently allow improved irrigation scheduling. On the other hand, dense‐resolution proximal soil sensing allows identifying spatial variability …

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Scale-Dependent Angle Of Alignment Between Velocity And Magnetic Field Fluctuations In Solar Wind Turbulence, J. J. Podesta, Benjamin D.G. Chandran, A. Bhattacharjee, D. A. Roberts, M. L. Goldstein Jan 2009

Scale-Dependent Angle Of Alignment Between Velocity And Magnetic Field Fluctuations In Solar Wind Turbulence, J. J. Podesta, Benjamin D.G. Chandran, A. Bhattacharjee, D. A. Roberts, M. L. Goldstein

Physics & Astronomy

Under certain conditions, freely decaying magnetohydrodynamic (MHD) turbulence evolves in such a way that velocity and magnetic field fluctuations delta v and delta B approach a state of alignment in which delta v proportional to delta B. This process is called dynamic alignment. Boldyrev has suggested that a similar kind of alignment process occurs as energy cascades from large to small scales through the inertial range in strong incompressible MHD turbulence. In this study, plasma and magnetic field data from the Wind spacecraft, data acquired in the ecliptic plane near 1 AU, are employed to investigate the angle theta(tau) between …

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Characterization And Synthesis Of Nanoscale Materials, Jinfeng Wang Jan 2009

Characterization And Synthesis Of Nanoscale Materials, Jinfeng Wang

Dissertations

This dissertation focuses on the systematic study of techniques for characterization and synthesis of nanoscale materials. We have achieved several goals. Firstly, high number density uniform zinc oxide nanostructure growth has been achieved using thermal evaporation, through control of experimental parameters that include source material temperature, substrate temperature, substrate material, gas flow rate, and choice of catalyst. Aligned zinc oxide nanowires, randomly oriented zinc oxide nanowires, zinc oxide container-shaped structures, and zinc oxide nanobelts have been synthesized with high yield. Secondly, using a one parameter family of lattice fringe geometry curves, we show how to examine the epitaxial relationship between …

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Intradot Dynamics Of Inas Quantum Dot Based Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Gillian Madden, Guillaume Huyet, Et. Al. Jan 2009

Intradot Dynamics Of Inas Quantum Dot Based Electroabsorbers, T. Piwonski, Jaroslaw Pulka, Gillian Madden, Guillaume Huyet, Et. Al.

Physical Sciences Publications

The carrier relaxation and escape dynamics of InAs/GaAs quantum dot waveguide absorbers is studied using heterodyne pump-probe measurements. Under reverse bias conditions, we reveal differences in intradot relaxation dynamics, related to the initial population of the dots’ ground or excited states. These differences can be attributed to phonon-assisted or Auger processes being dominant for initially populated ground or excited states, respectively.

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Exhumation Of The Inyo Mountains, California: Implications For The Timing Of Extension Along The Western Boundary Of The Basin And Range Province And Distribution Of Dextral Fault Slip Rates Across The Eastern California Shear Zone, Jeffrey Lee, Daniel F. Stockli, Lewis A. Owen, Robert C. Finkel, Roman Kislitsyn Jan 2009

Exhumation Of The Inyo Mountains, California: Implications For The Timing Of Extension Along The Western Boundary Of The Basin And Range Province And Distribution Of Dextral Fault Slip Rates Across The Eastern California Shear Zone, Jeffrey Lee, Daniel F. Stockli, Lewis A. Owen, Robert C. Finkel, Roman Kislitsyn

All Faculty Scholarship for the College of the Sciences

New geologic mapping, tectonic geomorphologic, 10Be terrestrial cosmogenic nuclide, and (U-Th)/He zircon and apatite thermochronometric data provide the first numerical constraints on late Cretaceous to late Quaternary exhumation of the Inyo Mountains and vertical slip and horizontal extension rates across the eastern Inyo fault zone, California. The east-dipping eastern Inyo fault zone bounds the eastern flank of the Inyo Mountains, a prominent geomorphic feature within the western Basin and Range Province and eastern California shear zone. (U-Th)/He zircon and apatite thermochronometry yield age patterns across the range that are interpreted as indicating: (1) two episodes of moderate to rapid …

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Synthesis And Applications Of Polycationic Organic Salts, Collaborative Project Jan 2009

Synthesis And Applications Of Polycationic Organic Salts, Collaborative Project

Dyson College- Seidenberg School of CSIS : Collaborative Projects and Presentations

This entry adheres to the use of the quad chart template to provide a succint description only of the current research project undertaken by the participants. It provides for the following information

1. Participants and Affiliations
2. Overall Project Goals
3. Illustrative Picture
4. Specific research/artistic/pedagogic foci

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Measurement Of The Angular And Lifetime Parameters Of The Decays BD0 → J/ΨK*0 And BS0 → J/Φψ, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration Jan 2009

Measurement Of The Angular And Lifetime Parameters Of The Decays BD0 → J/ΨK*0 And BS0 → J/Φψ, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We present measurements of the linear polarization amplitudes and the strong relative phases that describe the flavor-untagged decays Bd0 → J/ψK+0 and Bs0 → J/ψφ in the transversity basis. We also measure the mean lifetime τs of the Bd0 mass eigenstates and the lifetime ratio τs/τd. The analyses are based on approximately 2.8 fb-1 of data recorded with the D0 detector. From our measurements of the angular parameters we conclude that there is no evidence for a deviation from flavor SU(3) symmetry for these …

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