Physical Sciences and Mathematics Commons^™

Renormalization Of The Tunnel Splitting In A Rotating Nanomagnet, Michael F. O'Keeffe, Eugene M. Chudnovsky

Publications and Research

We study spin tunneling in a magnetic nanoparticle with biaxial anisotropy that is free to rotate about its anisotropy axis. Exact instanton of the coupled equations of motion is found that connects degenerate classical energy minima. We show that mechanical freedom of the particle renormalizes magnetic anisotropy and increases the tunnel splitting.

Quantum Tunneling Of The Interfaces Between Normal-Metal And Superconducting Regions Of A Type-I Pb Superconductor, Eugene M. Chudnovsky, S Velez, A Garcia-Santiago, J A. Hernandez

Publications and Research

Evidence of a non-thermal magnetic relaxation in the intermediate state of a type-I superconducor is presented. It is attributed to quantum tunneling of interfaces separating normal and superconducting regions. Tunneling barriers are estimated and temperature of the crossover from thermal to quantum regime is obtained from Caldeira-Leggett theory. Comparison between theory and experiment points to tunneling of interface segments of size comparable to the coherence length, by steps of order one nanometer.

Thermal Diffractive Corrections To Casimir Energies, Daniel N. Kabat, Dimitra Karabali

Publications and Research

We study the interplay of thermal and diffractive effects in Casimir energies. We consider plates with edges, oriented either parallel or perpendicular to each other, as well as a single plate with a slit. We compute the Casimir energy at finite temperature using a formalism in which the diffractive effects are encoded in a lower dimensional non-local field theory that lives in the gap between the plates. The formalism allows for a clean separation between direct or geometric effects and diffractive effects, and makes an analytic derivation of the temperature dependence of the free energy possible. At low temperatures, with …

Constructing Local Bulk Observables In Interacting Ads/Cft, Daniel N. Kabat, Gilad Lifschytz, David A. Lowe

Publications and Research

Local operators in the bulk of AdS can be represented as smeared operators in the dual CFT. We show how to construct these bulk observables by requiring that the bulk operators commute at spacelike separation. This extends our previous work by taking interactions into account. Large-N factorization plays a key role in the construction. We show diagrammatically how this procedure is related to bulk Feynman diagrams.

Differential Microlensing Measurements Of Quasar Broad-Line Kinematics In Q2237+0305, Matthew J. O'Dowd, N F. Bate, R L. Webster, R Wayth

Publications and Research

The detailed workings of the central engines of powerful quasars remain a mystery. This is primarily due to the fact that, at their cosmological distances, the inner regions of these quasars are spatially unresolvable. Reverberation mapping is now beginning to unlock the physics of the Broad Emission Line Region (BELR) in nearby, low-luminosity quasars, however it is still unknown whether this gas is dominated by virial motion, by outflows, or infall. The challenge is greater for more distant, powerful sources due to the very long response time of the BELR to changes in the continuum. We present a new technique …

Hořava Gravity: Symmetries And Generalized Particle Dynamics, Dario Capasso

Dissertations, Theses, and Capstone Projects

In the search for a theory of Quantum Gravity a new proposal was recently made by P. Hořava. The main feature of this new proposed theory is that it is power-counting renormalizable by construction, and could prove to be truly renormalizable, although more work is needed in this direction.

The renormalizability of the theory is a central issue. Indeed, General Relativity does not have this property, implying that to construct its quantum version we need to “complete” the theory in the UV. Hořava suggested a possible way to provide a UV completion of GR by giving up full spacetime reparametrization …

Graphs Of Bounded Degree And The P-Harmonic Boundary, Michael J. Puls

Publications and Research

Let p be a real number greater than one and let G be a connected graph of bounded degree. We introduce the p-harmonic boundary of G and use it to characterize the graphs G for which the constant functions are the only p-harmonic functions on G. We show that any continuous function on the p-harmonic boundary of G can be extended to a function that is p-harmonic on G. We also give some properties of this boundary that are preserved under rough-isometries. Now let Gamma be a finitely generated group. As an application of our results, we characterize the vanishing …

Hybrid Micro-/Nanogels For Optical Sensing And Intracellular Imaging, Weitai Wu, Shuiqin Zhou

Publications and Research

Hybrid micro-/nanogels are playing an increasing important part in a diverse range of applications, due to their tunable dimensions, large surface area, stable interior network structure, and a very short response time. We review recent advances and challenges in the developments of hybrid micro-/nanogels toward applications for optical sensing of pH, temperature, glucose, ions, and other species as well as for intracellular imaging. Due to their unique advantages, hybrid micro-/nanogels as optical probes are attracting substantial interests for continuous monitoring of chemical parameters in complex samples such as blood and bioreactor fluids, in chemical research and industry, and in food …

The Mycobacterium Tuberculosis Drugome And Its Polypharmacological Implications, Sarah L. Kinnings, Li Xie, Kingston H. Fung, Richard M. Jackson, Lei Xie, Phillip E. Bourne

Publications and Research

We report a computational approach that integrates structural bioinformatics, molecular modelling and systems biology to construct a drug-target network on a structural proteome-wide scale. The approach has been applied to the genome of Mycobacterium tuberculosis (M.tb), the causative agent of one of today’s most widely spread infectious diseases. The resulting drug-target interaction network for all structurally characterized approved drugs bound to putative M.tb receptors, we refer to as the ‘TB-drugome’. The TB-drugome reveals that approximately one-third of the drugs examined have the potential to be repositioned to treat tuberculosis and that many currently unexploited M.tb receptors may be chemically druggable …

Upper Cretaceous Peay Bentonites (North-Central Wyoming): Provenance And Tectonics Interpretation From Ash Composition, Nazrul I. Khandaker, Carl F. Vondra, Karl E. Seifert, Malek Shami, Rochelle Cardinale, Thakur Chaturgan

Publications and Research

The Peay bentonites belong to the basal Frontier Formation (Bighorn Basin, north-central Wyoming), primarily outcrop in the Bighorn Basin, rest on an extensively bioturbated sandstone unit, the Peay Sandstone, and are generally the thinner bentonitic unit. Beds of very light gray to greenish gray bentonite are also abundant in the lower Frontier units between Kaycee and Mayoworth (Powder River Basin) and are very rarely as much as 3 m thick. Bentonite occurs within the interstratified shale, sandstone, and siltstone sequences of the lower Frontier unit throughout much of the southwestern Powder River Basin. The purpose of this study is to …

Tensorial Reconstruction At The Integrand Level, G. Heinrich, Giovanni Ossola, T. Reiter, F. Tramontano

Publications and Research

We present a new approach to the reduction of one-loop amplitudes obtained by reconstructing the tensorial expression of the scattering amplitudes. The reconstruction is performed at the integrand level by means of a sampling in the integration momentum. There are several interesting applications of this novel method within existing techniques for the reduction of one-loop multi-leg amplitudes: to deal with numerically unstable points, such as in the vicinity of a vanishing Gram determinant; to allow for a sampling of the numerator function based on real values of the integration momentum; to optimize the numerical reduction in the case of long …

An Application Of Statistical Technique To Correct Satellite Data Due To Orbit Degradation, Md Zahidur Rahman, Leonid Roytman, Run Jesmin

Publications and Research

This paper apply an statistical technique to correct radiometric data measured by Advanced Very High Resolution Radiometers(AVHRR) onboard the National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting Environmental Satellites(POES). This paper study Normalized Difference Vegetation Index (NDVI) stability in the NOAA/NESDIS Global Vegetation Index (GVI) data for the period 1982-2003. AVHRR weekly data for the five NOAA afternoon satellites NOAA-7, NOAA-9, NOAA-11, NOAA-14, and NOAA-16 are used for the China dataset, for it includes a wide variety or different ecosystems represented globally. GVI has found wide use for studying and monitoring land surface, atmosphere, and recently for analyzing climate and …

Drug Off-Target Effects Predicted Using Structural Analysis In The Context Of A Metabolic Network Model, Roger L. Chang, Lei Xie, Philip E. Bourne, Bernhard O. Palsson

Publications and Research

Recent advances in structural bioinformatics have enabled the prediction of protein-drug off-targets based on their ligand binding sites. Concurrent developments in systems biology allow for prediction of the functional effects of system perturbations using large-scale network models. Integration of these two capabilities provides a framework for evaluating metabolic drug response phenotypes in silico. This combined approach was applied to investigate the hypertensive side effect of the cholesteryl ester transfer protein inhibitor torcetrapib in the context of human renal function. A metabolic kidney model was generated in which to simulate drug treatment. Causal drug off-targets were predicted that have previously been …

Enumeration Refactoring: A Tool For Automatically Converting Java Constants To Enumerated Types, Raffi Khatchadourian, Benjamin Muskalla

Publications and Research

Java 5 introduces several new features that significantly improve older Java technology. We consider the new enum construct, which provides language support for enumerated types. Before Java 5, programmers needed to employ various patterns to compensate for the absence of enumerated types in Java. Unfortunately, these compensation patterns lack several highly desirable properties of the enum construct, notably type-safety. We demonstrate an automated refactoring tool called Convert Constants to Enum for transforming legacy Java code to use the new enumeration construct. An interprocedural type inferencing algorithm that tracks the flow of enumerated values drives the approach, and the tool is …

Scattering Amplitudes From Unitarity-Based Reduction Algorithm At The Integrand-Level, P. Mastrolia, Giovanni Ossola, T. Reiter, F. Tramontano

Publications and Research

Samurai is a tool for the automated numerical evaluation of one-loop corrections to any scattering amplitudes within the dimensional-regularization scheme. It is based on the decomposition of the integrand according to the OPP-approach, extended to accommodate an implementation of the generalized d-dimensional unitarity-cuts technique, and uses a polynomial interpolation exploiting the Discrete Fourier Transform. samurai can process integrands written either as numerator of Feynman diagrams or as product of tree-level amplitudes. We discuss some applications, among which the 6- and 8-photon scattering in QED, and the 6-quark scattering in QCD. samurai has been implemented as a Fortran90 library, publicly available, …

Optimizing Radiology Peer Review: A Mathematical Model For Selecting Future Cases Based On Prior Errors, Yun Robert Sheu, Elie Feder, Igor Balsim, Victor F. Levin, Andrew G. Bleicher, Barton F. Branstetter Iv

Publications and Research

Introduction: Peer review is an essential process for physicians because it facilitates improved quality of patient care and continuing physician learning and improvement. However, peer review often is not well received by radiologists, who note that it is time intensive, subjective, and lacks demonstrable impact on patient care. Current advances in peer review include the RADPEER system with its standardization of discrepancies and incorporation of the peer review process into the PACS itself. Our purpose was to build on RADPEER and similar systems by using a mathematical model to optimally select the types of cases to be reviewed, for each …

Sensitivity Analysis Of B-Factor In Microwave Emission Model For Soil Moisture Retrieval: A Case Study For Smap Mission, Dugwon Seo, Tarendra Lakhankar, Reza Khanbilvardi

Publications and Research

Sensitivity analysis is critically needed to better understand the microwave emission model for soil moisture retrieval using passive microwave remote sensing data. The vegetation b-factor along with vegetation water content and surface characteristics has significant impact in model prediction. This study evaluates the sensitivity of the b-factor, which is function of vegetation type. The analysis is carried out using Passive and Active L and S-band airborne sensor (PALS) and measured field soil moisture from Southern Great Plains experiment (SGP99). The results show that the relative sensitivity of the b-factor is 86% in wet soil condition and 88% in high vegetated …

Smap-Ws: A Parallel Web Service For Structural Proteome-Wide Ligand-Binding Site Comparison, Jingyuan Ren, Lei Xie, Wilfred W. Li, Philip E. Bourne

Publications and Research

The proteome-wide characterization and analysis of protein ligand-binding sites and their interactions with ligands can provide pivotal information in understanding the structure, function and evolution of proteins and for designing safe and efficient therapeutics. The SMAP web service (SMAP-WS) meets this need through parallel computations designed for 3D ligand-binding site comparison and similarity searching on a structural proteome scale. SMAP-WS implements a shape descriptor (the Geometric Potential) that characterizes both local and global topological properties of the protein structure and which can be used to predict the likely ligand-binding pocket [Xie,L. and Bourne,P.E. (2007) A robust and efficient algorithm for …

Tredd—A Database For Tandem Repeats Over The Edit Distance, Dina Sokol, Firat Atagun

Publications and Research

A ‘tandem repeat’ in DNA is a sequence of two or more contiguous, approximate copies of a pattern of nucleotides. Tandem repeats are common in the genomes of both eukaryotic and prokaryotic organisms. They are significant markers for human identity testing, disease diagnosis, sequence homology and population studies. In this article, we describe a new database, TRedD, which contains the tandem repeats found in the human genome. The database is publicly available online, and the software for locating the repeats is also freely available. The definition of tandem repeats used by TRedD is a new and innovative definition based upon …

Contribution Of Soil Moisture Feedback To Hydroclimatic Variability, Nir Krakauer, B. I. Cook, M. J. Puma

Publications and Research

While a variety of model experiments and analyses of observations have explored the impact of soil moisture variation on climate, it is not yet clear how large or detectable soil moisture feedback is across spatial and temporal scales. Here, we study the impact of dynamic versus climatological soil moisture in the GISS GCM ModelE (with prescribed sea-surface temperatures) on the variance and on the spatial and temporal correlation scale of hydrologically relevant climate variables (evaporation, precipitation, temperature, cloud cover) over the land surface. We also confirm that synoptic variations in soil moisture have a substantial impact on the mean climate …

Identification And Quantitation Of 3,4-Methylenedioxy-N-Methylamphetamine (Mdma, Ecstasy) In Human Urine By 1h Nmr Spectroscopy. Application To Five Cases Of Intoxication, Jonathan Liu, John Decatur, Gloria Proni, Elise Champeil

Publications and Research

Identification of 3,4-methylenedioxy-N-methylamphetamine (MDMA, ecstasy) in five cases of intoxication using nuclear magnetic resonance (NMR) spectroscopy of human urine is reported. A new water suppression technique PURGE (Presaturation Utilizing Relaxation Gradients and Echoes) was used. A calibration curve was obtained using spiked samples. The method gave a linear response (correlation coefficient of 0.992) over the range 0.01–1 mg/mL. Subsequently, quantitation of the amount of MDMA present in the samples was performed. The benefit and reliability of NMR investigations of human urine for cases of intoxication with MDMA are discussed.

On The Feasibility Of A Timely Transition To A More Sustainable Energy Future, Micha Tomkiewicz

Publications and Research

The paper uses the framework of the IPAT equation, as applied to CO2 emission, to decompose the various driving forces in the global energy use. Data from recent history are superimposed on projections of SRES IPCC scenarios to determine if enough sustainable capacity can be built to prevent irreversible ecological deterioration. The conclusion from the analysis is that, in agreement with the IPCC 4th report, until about 2030 there are no large differences between a sustainable scenario and the one that resembles “business as usual”. The sharp divergence that follows stems from different estimates in population growth and in the …

Tr-2010012: Randomized Preconditioning Of Linear Systems Of Equations, Victor Y. Pan, Guoliang Qian, Ai-Long Zheng

Computer Science Technical Reports

No abstract provided.

Tr-2010013: Matrix Computations And Polynomial Root-Finding With Preprocessing, Victor Y. Pan, Guoliang Qian, Ai-Long Zheng, Zhao Chen

Computer Science Technical Reports

No abstract provided.

Tr-2010014: A Complexity Question In Justification Logic, Antonis Achilleos

Computer Science Technical Reports

No abstract provided.

Tr-2010015: New Progress In Real And Complex Polynomial Root-Finding, Victor Y. Pan, Ai-Long Zheng

Computer Science Technical Reports

No abstract provided.

Tr-2010009: Solving Linear Systems With Randomized Augmentation Ii, Victor Y. Pan, Guoliang Qian

Computer Science Technical Reports

No abstract provided.

Tr-2010002: Reasoning About Games, Melvin Fitting

Computer Science Technical Reports

No abstract provided.

Tr-2010003: The Impossibility Of Definitive Solutions For Some Games, Sergei Artemov

Computer Science Technical Reports

No abstract provided.

Tr-2010005: Securing Bgp Through Existing Infrastructure And Contractual Chains (Ccbgp), Yuri Cantor, Nancy Griffeth, Bilal Khan, Ping Ji

Computer Science Technical Reports

No abstract provided.