Physical Sciences and Mathematics Commons^™

Towards The Rational Design Of Mri Contrast Agents: A Practical Approach To The Synthesis Of Gadolinium Complexes That Exhibit Optimal Water Exchange, Mark Woods, Mauro Botta, Stefano Avedano, Jing Wang, A. Dean Sherry

Chemistry Faculty Publications and Presentations

The gadolinium(III) complex of S-SSSS-NO₂BnDOTMA exhibits water exchange kinetics that are optimal for use in high relaxivity or targeted contrast agents. However, the synthesis of this ligand is hampered by the steric encumbrance imparted upon the cyclen ring by the nitrobenzyl substituent. A relatively simple modification has been used to enable the synthesis of larger quantities of a bifunctional ligand that retains similar fast water exchange properties. The gadolinium complex of S-SSS-NO₂BnDO3MA-1A is shown to retain the rapid water exchange kinetics characteristic of a twisted square antiprismatic (TSAP) …

Satellite-Observed Photosynthetic Trends Across Boreal North America Associated With Climate And Fire Disturbance, Scott J. Goetz, Andrew Godard Bunn, Gregory J. Fiske, Richard A. Houghton

Environmental Sciences Faculty and Staff Publications

We analyzed trends in a time series of photosynthetic activity across boreal North America over 22 years (1981 through 2003). Nearly 15% of the region displayed significant trends, of which just over half involved temperature-related increases in growing season length and photosynthetic intensity, mostly in tundra. In contrast, forest areas unaffected by fire during the study period declined in photosynthetic activity and showed no systematic change in growing season length. Stochastic changes across the time series were predominantly associated with a frequent and increasing fire disturbance regime. These trends have implications for the direction of feedbacks to the climate system …

A Cryptographic Solution For General Access Control, Y. Kong, Jennifer Seberry, J. R. Getta, Ping Yu

Faculty of Informatics - Papers (Archive)

As one of the most popular information safeguarding mechanisms, access control is widely deployed in information systems. However, access control approach suffers from a tough problem, i.e. system administrators must be unconditionally trusted. Cryptographic substitutes have been developed to solve the above problem. In particular, hierarchical encryption, as an alternate solution of access control in a hierarchy, has been intensively studied. In this paper, we propose a cryptographic solution for general access control based on Chinese Remainder Theorem. Our solution has two categories: data based solution and key based solution. In contrast to the most recent hierarchical encryption system: Ray, …

Red Rock Desert Learning Center Core Group Meeting: September 20, 2005, Red Rock Desert Learning Center

Reports (RRLC)

1. Introductions & Announcements (5 min.)
2. Approval of Minutes from August 16, 2005 Meeting (5 min.)
3. Discussion of Scope/Design Issues –Michael Reiland/David Frommer (30 min.)
4. Cost Update – Michael Reiland (15 min.)
5. Schedule Update – Michael Reiland (15 min.)
6. Standing Reports (15 minutes)
   A. Line and Space Architects – Les Wallach/Henry Tom
   B. BLM Capital Improvements – Michael Reiland
   C. Community Outreach – Nancy Flagg
7. Committee Reports (5 min.)
   A. Building Committee – Angie Lara
   B. Design Oversight – David Frommer
   C. Educational Programs – Paul Buck
   D. Fund-raising and Partnerships – Blaine Benedict
   E. NEPA – Michael Johnson
   F. Operations …

Enhanced Anomalous Scattering By Superconducting Nanofilms Vs T At O:K, Cu:L2,3 , Ba:M4,5 Edges, Juana Acrivos

Faculty Publications, Chemistry

Enhanced (001) anomalous scattering by YBa2Cu3O7-δ 50 nm films on SrTiO3 substrates with and without a grain boundary versus temperature is interpreted using crystallographic weights to distinguish it from total electron yield and fluorescence spectra. The power of diffraction enhancement is to ascertain the film oxygen composition from the changes in the c-axis, c0 as the film surface is scanned across the grain boundary, and to determine that c0 is constantversus temperature across the superconducting phase transition.

Creation Of Optical Vortices In Femtosecond Pulses, I. G. Mariyenko, James Strohaber, Cornelis J. Uiterwaal

C.J.G.J. Uiterwaal Publications

We experimentally created a femtosecond optical vortex using a pair of computer-synthesized holographic gratings arranged in a 2f - 2f optical setup. We present measurements showing that the resulting donut mode is free of spatial chirp, and support this finding with an analysis of the optical wave propagation through our system based on the Kirchhoff- Fresnel diffraction integral. An interferogram confirms that our ultrashort vortex has topological charge 1, and a conservative experimental estimation of its duration is 280 fs. We used 25-fs radiation pulses (bandwidth approximately 40 nm) produced by a Ti:sapphire laser oscillator.

Effective Field Theory Program For Conformal Quantum Anomalies, Horacio E. Camblong

Physics and Astronomy

The emergence of conformal states is established for any problem involving a domain of scales where the long-range SO(2,1) conformally invariant interaction is applicable. Whenever a clear-cut separation of ultraviolet and infrared cutoffs is in place, this renormalization mechanism is capable of producing binding in the strong-coupling regime. A realization of this phenomenon, in the form of dipole-bound anions, is discussed.

Discretisation For Odd Quadratic Twists, J. Brian Conrey, Michael O. Rubinstein, Nina C. Snaith, Mark Watkins

Mathematics - All Scholarship

The discretisation problem for even quadratic twists is almost understood, with the main question now being how the arithmetic Delaunay heuristic interacts with the analytic random matrix theory prediction. The situation for odd quadratic twists is much more mysterious, as the height of a point enters the picture, which does not necessarily take integral values (as does the order of the Shafarevich-Tate group). We discuss a couple of models and present data on this question.

Executable Specifications For Agent Oriented Conceptual Modelling, Y. Guan, Aditya K. Ghose

Faculty of Informatics - Papers (Archive)

Agent-oriented conceptual modelling (AoCM) notations such as i* have received considerable recent attention as a useful approach to early-phase requirements engineering. AoCM notations are useful in modeling organizational context and in offering high-level anthropomorphic abstractions as modeling constructs. AoCM notations such as i* help answer questions such as what goals exist, how key actors depend on each other and what alternatives must be considered. In this paper, we suggest an approach to executing i* models by translating these into set of interacting agents implemented in the 3APL language. In addition, we suggest a hybrid modeling, or co-evolution, approach in which …

Rank Distribution In A Family Of Cubic Twists, Mark Watkins

Mathematics - All Scholarship

In 1987, Zagier and Kramarz published a paper in which they presented evidence that a positive proportion of the even-signed cubic twists of the elliptic curve x³+y³=1 should have positive rank. We extend their data, showing that it is more likely that the proportion goes to zero.

Further Studies Of Single-Sided Charge-Sharing Czt Strip Detectors, B Donmez, John R. Macri, Mark L. Mcconnell, James M. Ryan, Mark Widholm, T Narita, L A. Hamel

Space Science Center

We report progress in the study of a thick CZT strip detector module designed to perform gamma-ray spectroscopy and 3-D imaging. We report preliminary performance measurements of 7.5 mm thick single-sided charge-sharing strip detector prototype devices. This design features both row and column contacts on the anode surface. This electron-only approach addresses problems associated with poor hole transport in CZT that limit the thickness and energy range of double-sided strip detectors. This work includes laboratory and simulation studies aimed at developing compact, efficient, detector modules for 0.05 to 1 MeV gamma measurements while minimizing the number and complexity of the …

Activation Of Carboplatin By Carbonate, Anthony J. Di Pasqua, Jerry Goodisman, Deborah J. Kerwood, Bonnie B. Toms, James C. Dabrowiak

Chemistry - All Scholarship

Carboplatin, [Pt(NH3)2(CBDCA-O,O')], 1, where CBDCA is cyclobutane-1,1-dicarboxylate, is in wide clinical use for the treatment of ovarian, lung, and other types of cancer. Because carboplatin is relatively unreactive toward nucleophiles, an important question concerning the drug is the mechanism by which it is activated in vivo. Using [1H,15N] heteronuclear single quantum coherance spectroscopy (HSQC) NMR and 15N-labeled carboplatin, we show that carboplatin reacts with carbonate ion in carbonate buffer to produce ring-opened products, the nature of which depends on the pH of the medium. The assignment of HSQC NMR resonances was facilitated by studying the reaction of carboplatin in strong …

Circular Dichroism In Classical Coulomb Scattering Involving Bremsstrahlung, A. A. Krylovetsky, N. L. Manakov, S. I. Marmo, Anthony F. Starace

Department of Physics and Astronomy: Faculty Publications

Classical orbit derivations of the triply differential cross section for electron bremsstrahlung (BrS) in a Coulomb field are presented; the classical origin of the circular dichroism effect in the electron scattering angular distributions is established for both spontaneous and laser-stimulated BrS.

Importance Resampling For Global Illumination, Justin F. Talbot

Theses and Dissertations

This thesis develops a generalized form of Monte Carlo integration called Resampled Importance Sampling. It is based on the importance resampling sample generation technique. Resampled Importance Sampling can lead to significant variance reduction over standard Monte Carlo integration for common rendering problems. We show how to select the importance resampling parameters for near optimal variance reduction. We also combine RIS with stratification and with Multiple Importance Sampling for further variance reduction. We demonstrate the robustness of this technique on the direct lighting problem and achieve up to a 33% variance reduction over standard techniques. We also suggest using RIS as …

The Future Of Journal Publishing, Gordon C. Tibbitts

Gordon C. Tibbitts III

The seminar helped publishing neophytes understand where they can add value. It also focused on the challenges of the day and likely challenges in the future. Some predictions include a complete move to e-journals, article-at-a-time publishing, an increase in "meta" articles, and the demise of general search engine prominence.

Systematic, Multisite Short-Range-Order Corrections To The Electronic Structure Of Disordered Alloys From First Principles: The Kkr Nonlocal Cpa From The Dynamical Cluster Approximation, D. A. Biava, Subhradip Ghosh, Duane D. Johnson, W. A. Shelton, Andrei V. Smirnov

Duane D. Johnson

Although the Korringa-Kohn-Rostoker coherent-potential approximation (KKR-CPA) is used widely to configurationally average and get electronic structures and energies of disordered alloys, a single-site CPA misses local environment effects, including short-range order (SRO). A proposed nonlocal CPA (NLCPA) recovers translational invariance of the effective medium via k-space coarse graining from the dynamical cluster approximation (DCA), where corrections are systematic as cluster size increases. We implement a first-principles KKR-NLCPA/DCA and show the effects of environment, including SRO, on the electronic structures of fcc CuAu and bcc NiAl.

1,3-Bis(9-Ethyl­Carbazol-3-Yl)Propane, Erol Asker, John Masnovi

Chemistry Faculty Publications

In the title compund, C₃₁H₃₀N₂, π–π overlap is absent in the region where carbazole groups of two adjacent mol­ecules are inclined toward each other. The eth­yl groups which protrude from the plane of the carbazole groups and the alkyl­ene chain connecting the two carbazole groups are responsible for the poor mol­ecular stacking.

Electrochemical Attachment Of Motile Bacterial Cells To Gold, Sergey Rozhok, Richard C. Holz

Chemistry Faculty Research and Publications

Selective attachment of Escherichia coli K-12 bacterial cells to charged gold surfaces was demonstrated. Electrostatic binding of E. coli K-12 bacterial cells to positively charged surfaces was observed starting at +750 mV. The binding of E. coli K-12 cells to positively charged gold surfaces is proposed to occur due to long-range electrostatic interactions between the negatively charged O-chain of lipopolysaccharide (LPS) molecules protruding the bacterial cell body and the electrode surface. Removing LPS alters the cellular surface charge and results in cellular attachment to negatively charged surfaces. Thus, applying an electrical potential allows for the direct, real time detection of …

Persistent And Radiation-Induced Currents In Distorted Quantum Rings, Yuriy V. Pershin Dr, Carlo Piermarocchi

Faculty Publications

Persistent and radiation-induced currents in distorted narrow quantum rings are theoretically investigated. We show that ring distorsions can be described using a geometrical potential term. We analyze the effect of this term on the current induced by a magnetic flux (persistent current) and by a polarized coherent electromagnetic field (radiation-induced current). The strongest effects in persistent currents are observed for distorted rings with a small number of electrons. The distortion smoothes the current oscillations as a function of the magnetic flux and changes the temperature dependence of the current amplitude. For radiation-induced currents, the distortion induces an ac component in …

The Coadsorption And Interaction Of Molecular Icosahedra With Mercury, C.C. Ilie, Snjezana Balaz, Luis G. Rosa, Jun Zhang, P. Lunca-Popa, C. Bianchetti, R. Tittsworth, Jennifer I. Brand, B. Doudon, Peter A. Dowben

Peter Dowben Publications

We have investigated the changes in the electronic structure of molecularly adsorbed orthocarborane films, as a function of Hg co-adsorption, using photo emission. The interaction between Hg and molecular orthocarborane is weak and results in the formation of some small aggregates of Hg. This behavior is very different from alkali metals interaction with molecular carborane films and the interaction of Hg with semiconducting boron carbide films. Hg doping of semiconducting boron carbide may decrease the activation barrier for intrinsic carrier mobility, but does not significantly increase the number of carriers.

Google Scholar: Experiences Ideas And Plans, Gordon C. Tibbitts

Gordon C. Tibbitts III

This presentation is based on a synthesis of lessons learned in working with Google on the development of Google Scholar. A convergence of needs and developments bolstered support for federated searching, a greater number of publishers providing Google access to crawl their content, and the emergence of Google Scholar as a strong tool overshadowing any effort by publishers to launch a cooperative scholarly search engine. This presentation surveys what Google Scholar is currently use and what users are saying about it. Some found the inaccuracies and ubiquity of lower quality content troublesome. Opportunities to improve coverage, search stability (search results …

On-Disk Sequence Cache (Odsc): Using Excess Disk Capacity To Increase Performance, Christopher Ryan Slade

Theses and Dissertations

We present an on-disk sequence cache (ODSC), which improves disk drive performance. An ODSC uses a separate disk partition to store disk data in the order that the operating system requests it. Storing data in this order reduces the amount of seeking that the disk drive must do. As a result, the average disk access time is reduced. Reducing the disk access time improves the performance of the system, especially when booting the operating system, loading applications, and when main memory is limited. Experiments show that our ODSC speeds up application loads by as much as 413%. Our ODSC also …

A Study Of Dissolved Oxygen Impairment, North Branch Of Onancock Creek, Accomack County, Virginia, Virginia Institute Of Marine Science

Reports

No abstract provided.

Charmed-Meson Decay Constants In Three-Flavor Lattice Qcd, James E. Hetrick, C. Aubin

All Faculty Articles - School of Engineering and Computer Science

We present the first lattice QCD calculation with realistic sea quark content of the D+-meson decay constant fD+. We use the MILC Collaboration’s publicly available ensembles of lattice gauge fields, which have a quark sea with two flavors (up and down) much lighter than a third (strange). We obtain fD+ = 201± 3 ±17 MeV, where the errors are statistical and a combination of systematic errors. We also obtain fDs = 249 ± 3 ±16 MeV for the Ds meson.

Digital Commons Presentation For Chemistry Department Faculty, Paul Royster

Department of Chemistry: Department Information

Why you should put your publications and other work online; how the Digital Commons can help you do that; copyright status of your publications; policies of publishers; policy of American Chemical Society.

A Nonstationary Negative Binomial Time Series With Time-Dependent Covariates: Enterococcus Counts In Boston Harbor, E. Andres Houseman, Brent Coull, James P. Shine

Harvard University Biostatistics Working Paper Series

Boston Harbor has had a history of poor water quality, including contamination by enteric pathogens. We conduct a statistical analysis of data collected by the Massachusetts Water Resources Authority (MWRA) between 1996 and 2002 to evaluate the effects of court-mandated improvements in sewage treatment. Motivated by the ineffectiveness of standard Poisson mixture models and their zero-inflated counterparts, we propose a new negative binomial model for time series of Enterococcus counts in Boston Harbor, where nonstationarity and autocorrelation are modeled using a nonparametric smooth function of time in the predictor. Without further restrictions, this function is not identifiable in the presence …

Nonlinear Dynamics In Ecosystem Response To Climatic Change: Case Studies And Policy Implications, Virginia R. Burkett, Douglas A. Wilcox, Wilcox Stottlemyer, Wylie Barrow, Dan Fagre, Jill Baron, Jeff Price, Jennifer L. Nielsen, Craig D. Allen, David L. Peterson, Greg Ruggerone, Thomas Doyle

United States Geological Survey: Staff Publications

Many biological, hydrological, and geological processes are interactively linked in ecosystems. These ecological phenomena normally vary within bounded ranges, but rapid, nonlinear changes to markedly different conditions can be triggered by even small differences if threshold values are exceeded. Intrinsic and extrinsic ecological thresholds can lead to effects that cascade among systems, precluding accurate modeling and prediction of system response to climate change. Ten case studies from North America illustrate how changes in climate can lead to rapid, threshold-type responses within ecological communities; the case studies also highlight the role of human activities that alter the rate or direction of …

Multistrange Baryon Elliptic Flow In Au+Au Collisions At √SNn=200 Gev, Star Collaboration, T.D. Gutierrez

Physics

We report on the first measurement of elliptic flow ν₂(p_T) of multistrange baryons Ξ⁻+Ξ⁺ and Ω⁻+Ω⁺ in heavy-ion collisions. In minimum-bias Au+Au collisions at √s_NN=200  GeV, a significant amount of elliptic flow, comparable to other nonstrange baryons, is observed for multistrange baryons which are expected to be particularly sensitive to the dynamics of the partonic stage of heavy-ion collisions. The p_T dependence of ν₂ of the multistrange baryons confirms the number of constituent quark scaling previously observed for lighter hadrons. These results support the idea that …

Molecular Discrimination Of Type-I Over Type-Ii Methionyl Aminopeptidases, Krzysztof Swierczek, Alicja J. Copik, Sabina I. Swierczek, Richard C. Holz

Chemistry Faculty Research and Publications

Two residues that are conserved in type-I methionyl aminopeptidases (MetAPs) but are absent in all type-II MetAPs are the cysteine residues (Escherichia coli MetAP-I:   C59 and C70) that reside at the back of the substrate recognition pocket. These Cys residues are 4.4 Å apart and do not form a disulfide bond. Since bacteria and fungi contain only type-I MetAPs while all human cells contain both type-I and type-II MetAPs, type-I MetAPs represent a novel antibiotic/antifungal target if type-I MetAPs can be specifically targeted over type-II. Based on reaction of the thiol-specific binding reagent 5,5‘-dithio-bis(2-nitrobenzoic acid) (DTNB) with the type-I …

Catlett-Burruss Research And Education Laboratory Dedication Ceremony, College Of William And Mary, Virginia Institute Of Marine Science, Chesapeake Bay National Estuarine Research Reserve In Virginia

Miscellaneous

Brochure for Dedication: Program of events celebrating the dedication of the Catlett-Burruss Research and Education Laboratory and honoring Dr. William Reay with the NOAA Environmental Hero Award.