Physical Sciences and Mathematics Commons^™

Modeling The Incubation Period Of Anthrax, Ron Brookmeyer, Elizabeth Johnson, Sarah Barry

Ron Brookmeyer

Models of the incubation period of anthrax are important to public health planners because they can be used to predict the delay before outbreaks are detected, the size of an outbreak and the duration of time that persons should remain on antibiotics to prevent disease. The difficulty is that there is little direct data about the incubation period in humans. The objective of this paper is to develop and apply models for the incubation period of anthrax. Mechanistic models that account for the biology of spore clearance and germination are developed based on a competing risks formulation. The models predict …

Coefficient Of Bohm Diffusion In Fully Ionized Plasma And Its Theoretical Proof, Ahmad Talaei, Reza Amrollahi

Ahmad Talaei

A Note On Empirical Likelihood Inference Of Residual Life Regression, Ying Qing Chen, Yichuan Zhao

Yichuan Zhao

Mean residual life function, or life expectancy, is an important function to characterize distribution of residual life. The proportional mean residual life model by Oakes and Dasu (1990) is a regression tool to study the association between life expectancy and its associated covariates. Although semiparametric inference procedures have been proposed in the literature, the accuracy of such procedures may be low when the censoring proportion is relatively large. In this paper, the semiparametric inference procedures are studied with an empirical likelihood ratio method. An empirical likelihood confidence region is constructed for the regression parameters. The proposed method is further compared …

High-Resolution Mapping In Manus Basin, C. Roman, V. Ferrini

Christopher N. Roman

Near-bottom seafloor mapping with precisely navigated deep submergence vehicles has become increasingly common in a range of oceanographic settings. Recent mapping efforts at deep-water hydrothermal vent sites have resulted in high-resolution (sub-meter) bathymetry datasets that can be used to identify morphological features associated with volcanic, tectonic, and hydrothermal processes. The resolution of these maps, and our ability to accurately quantify the complex morphologic details of hydrothermal structures has been limited by a number of variables including navigational accuracy, sonar settings (e.g. acoustic wavelength, sonar orientation, ping rate), survey parameters (e.g. altitude, speed), data density, and data processing techniques (e.g. gridding …

Lyapunov Exponents For Small Aspect Ratio Rayleigh-Benard Convection, Janet Scheel, M. Cross

Janet D. Scheel

Leading order Lyapunov exponents and their corresponding eigenvectors have been computed numerically for small aspect ratio, three-dimensional Rayleigh-Benard convection cells with no-slip boundary conditions. The parameters are the same as those used by Ahlers and Behringer [Phys. Rev. Lett. 40, 712 (1978)] and Gollub and Benson [J. Fluid Mech. 100, 449 (1980)] in their work on a periodic time dependence in Rayleigh-Benard convection cells. Our work confirms that the dynamics in these cells truly are chaotic as defined by a positive Lyapunov exponent. The time evolution of the leading order Lyapunov eigenvector in the chaotic regime will also be discussed. …

Electrostatic Assembly Of A Redox Catalysis System For Detection Of Glutamate, Alice Harper, Mark Anderson

Mark R. Anderson

Interfacial assemblies capable of determining glutamate by redox catalysis are prepared by electrostatic assembly of alternating layers of ferrocene poly(allylamine) polymer and glutamate oxidase on a gold electrode. Deposition of the polymer was confirmed in cyclic voltammetry measurements by the presence of a surface wave corresponding to the oxidation of the ferrocene group. In the presence of glutamate in the adjacent electrolyte solution, the current increases and approaches a pseudosteady state, consistent with redox catalysis. Electrodes modified with glutamate oxidase had a linear response to glutamate up to 0.0045 M with sensitivity of 20 μA/cm2 and a limit of detection …

Guiding Of Laser Beams In Plasmas By Radiation Cascade Compression, Serguei Y. Kalmykov, Gennady Shvets

Serge Youri Kalmykov

The near-resonant beatwave excitation of an electron plasma wave (EPW) can be employed for generating trains of few-fs electromagnetic pulses in rarefied plasmas. The EPW produces a co-moving index grating that induces a laser phase modulation at the beat frequency. Consequently, the cascade of sidebands red- and blue-shifted from the fundamental by integer multiples of the beat frequency is generated in the laser spectrum. When the beat frequency is lower than the electron plasma frequency, the phase chirp enables laser beatnote compression by the group velocity dispersion [S. Kalmykov and G. Shvets, Phys. Rev. E 73, 46403 (2006)]. In the …

Modeling An Outbreak Of Anthrax, Ron Brookmeyer

Ron Brookmeyer

Introduction

On October 2, 2001 a sixty-three-year-old Florida man who worked as a photo editor at a media publishing company was admitted to an emergency department complaining of nausea, vomiting, and fever. His symptoms began four days earlier on a recreational trip to North Carolina. The man died shortly thereafter. An astute clinician quickly made the surprising diagnosis of inhalational anthrax, which is a serious and deadly disease. The diagnosis was surprising because inhalational anthrax is extremely rare; only 18 cases were reported in the United States between 1900 and 1978. Public health officials at first believed that the Florida …

Optimizing The Expected Overlap Of Survey Samples Via The Northwest Corner Rule, Lenka Mach, Philip T. Reiss, Ioana Schiopu-Kratina

Philip T. Reiss

In survey sampling there is often a need to coordinate the selection of pairs of samples drawn from two overlapping populations so as to maximize or minimize their expected overlap, subject to constraints on the marginal probabilities determined by the respective designs. For instance, maximizing the expected overlap between repeated samples can stabilize the resulting estimates of change and reduce the costs of first contacts; minimizing the expected overlap can avoid overburdening respondents with multiple surveys. We focus on the important special case in which both samples are selected by simple random sampling without replacement (SRSWOR) conducted independently within each …

Climate Change And Late Pliocene Acceleration Of Erosion In The Himalaya, Katharine Huntington, Ann Blythe, Kip Hodges

Ann Blythe

Studies of active mountain ranges suggest that atmospheric and geodynamic processes may be strongly coupled through erosion — a hypothesis that has led to a debate over the relative importance of climate and far-field tectonic forcing in influencing erosion. We addressed this debate by developing the detailed long-term erosional history of a transect in the central Annapurna Range of Nepal for comparison with the climate and tectonic forcing histories of the region. Patterns of apatite fission-track and muscovite 40Ar/39Ar apparent ages with elevation indicate a five-fold increase in apparent erosion rate between 2.5 and 0.9 Ma ago. The time frame …

Nano And Microscale Adhesion Energy Measurement For Au-Au Contacts In Microswitch Structures, Nima Rahbar, Zong Zong, Yifang Cao, Wole Soboyejo

Nima Rahbar

This paper presents a study of adhesion energies that are relevant to Au–Au microswitch contacts at the nano- and micronscales. Adhesionmeasurements are obtained from cantilevered Aumicroelectromechanical system(MEMS)microswitch structures with varying lengths. Scanning electron microscopymeasurements of the microbeam profiles are combined with fracture mechanics model for the estimation of the adhesion energy. Adhesion contact and pull-off experiments are combined with theoretical models for the extraction of adhesion energies associated with Au-coated atomic force microscopy tips and Aumicroswitch substrates. Finite element method simulation was also performed to account for crack-tip shielding contributions from asperities in contact between Au–Au microscale cantilevered MEMS structure. …

Physical And Structural Basis For The Strong Interactions Of The -Impy- Central Pairing Motif In The Polyamide F-Impyim, K. Buchmueller, S. Bailey, D. Matthews, Z. Taherbhai, J. Register, Z. Davis, Chrystal Bruce, C. O'Hare, J. Hartley, M. Lee

Chrystal D. Bruce

The polyamide f-ImPyIm has a higher affinity for its cognate DNA than either the parent analogue, distamycin A (10-fold), or the structural isomer, f-PyImIm (250-fold), has for its respective cognate DNA sequence. These findings have led to the formulation of a two-letter polyamide “language” in which the -ImPy- central pairings associate more strongly with Watson−Crick DNA than -PyPy-, -PyIm-, and -ImIm-. Herein, we further characterize f-ImPyIm and f-PyImIm, and we report thermodynamic and structural differences between -ImPy- (f-ImPyIm) and -PyIm- (f-PyImIm) central pairings. DNase I footprinting studies confirmed that f-ImPyIm is a stronger binder than distamycin A and f-PyImIm and …

Traditional Medicine And Traditional Music In Madagascar, Nat Quansah

Nat Quansah

No abstract provided.

Bridging The Time And Frequency Domains Enables Raman Spectroscopy With Femtosecond Pulses, Sean Kern, Diana Urbanek, Sukhendu Nath, Mark Berg

Sean J. Kern

No abstract provided.

A Content-Driven Reputation System For The Wikipedia, B. Thomas Adler, Luca De Alfaro

Luca de Alfaro

On-line forums for the collaborative creation of bodies of information are a phenomenon of rising importance; the Wikipedia is one of the best-known examples. The open nature of such forums could benefit from a notion of reputation for its authors. Author reputation could be used to flag new contributions from low-reputation authors, and it could be used to allow only authors with good reputation to contribute to controversial or critical pages. A reputation system for the Wikipedia would also provide an incentive to give high-quality contributions.

We present in this paper a novel type of content-driven reputation system for Wikipedia …

Injection, Trapping, And Acceleration Of Electrons In A Three-Dimensional Nonlinear Laser Wakefield, Serguei Y. Kalmykov, Leonid M. Gorbunov, Patrick Mora, Gennady Shvets

Serge Youri Kalmykov

It is demonstrated that the accelerating and focusing phases of the nonlinear three-dimensional axisymmetric laser wake can almost entirely overlap starting from a certain distance behind the laser pulse in homogeneous plasma. Such field structure results from the curvature of phase fronts due to the radially inhomogeneous relativistic shift of plasma frequency. Consequently, the number of trapped low-energy electrons can be much greater than that predicted by the linear wake theory. This effect is favorable for quasi-monoenergetic acceleration of a considerable charge (several hundreds of pC) to about 1 GeV per electron in the plasma wakefield driven by an ultrashort …

Snapshots Of Laser Wakefields, Nicholas H. Matlis, Steven A. Reed, Stepan S. Bulanov, Vladimir Chvykov, Galina Kalintchenko, Takeshi Matsuoka, Pascal Rousseau, Victor Yanovsky, Anatoly Maksimchuk, Serguei Y. Kalmykov, Gennady Shvets, Michael C. Downer

Serge Youri Kalmykov

Tabletop plasma accelerators can now produce GeV-range electron beams and femtosecond X-ray pulses, providing compact radiation sources for medicine, nuclear engineering, materials science and high-energy physics. In these accelerators, electrons surf on electric fields exceeding 100 GeV m^{−1}, which is more than 1,000 times stronger than achievable in conventional accelerators. These fields are generated within plasma structures (such as Langmuir waves or electron density ‘bubbles’) propagating near light speed behind laser or charged-particle driving pulses. Here, we demonstrate single-shot visualization of laser-wakefield accelerator structures for the first time. Our ‘snapshots’ capture the evolution of multiple wake periods, detect structure variations …

Use Of Unbiased Estimating Equations To Estimate Correlation In Generalized Estimating Equation Analysis Of Longitudinal Trials, Wenguang Sun, Justine Shults, Mary Leonard

Justine Shults

In a recent publication, Wang and Carey (Journal of the American Statistical Association, 99, pp. 845-853, 2004) presented a new approach for estimation of the correlation parameters in the framework of generalized estimating equations (GEE). They considered correlated continuous, binary and count data with a generalized Markov correlation structure that includes the first-order autoregressive AR(1) and Markov structures as special cases. They made detailed comparisons with pseudo-likelihood (PL) and the first stage of quasi-least squares (QLS), a two-stage approach in the framework of generalized estimating equations (GEE). In this note we extend their comparisons for the second (bias corrected) stage …

Censored Data Regression In High-Dimension And Low-Sample Size Settings For Genomic Applications, Hongzhe Li

Hongzhe Li

New high-throughput technologies are generating various types of high-dimensional genomic and proteomic data and meta-data (e.g., networks and pathways) in order to obtain a systems-level understanding of various complex diseases such as human cancers and cardiovascular diseases. As the amount and complexity of the data increase and as the questions being addressed become more sophisticated, we face the great challenge of how to model such data in order to draw valid statistical and biological conclusions. One important problem in genomic research is to relate these high-throughput genomic data to various clinical outcomes, including possibly censored survival outcomes such as age …

All About 1089, Lara Pudwell

Lara K. Pudwell

No abstract provided.

Extended Collaboration Description Language (X-Codl), Jia Zhang

Jia Zhang

No abstract provided.

Simulation Of Ultrashort Laser Pulses In Nonlinear Media, Jeremy Gulley

Jeremy R. Gulley

No abstract is currently available.

The Aeroacoustics Of Turbulent Coanda Jet Flows, J. Fox, Caroline Lubert

Caroline P Lubert

No abstract provided.

Creating Custom Containers With Generative Techniques, Gabriel A. Moreno

Gabriel A. Moreno

Component containers are a key part of mainstream component technologies, and play an important role in separating nonfunctional concerns from the core component logic. This paper addresses two different aspects of containers. First, it shows how generative programming techniques, using AspectC++ and metaprogramming, can be used to generate stubs and skeletons without the need for special compilers or interface description languages. Second, the paper describes an approach to create custom containers by composing different non-functional features. Unlike component technologies such as EJB, which only support a predefined set of container types, this approach allows different combinations of non-functional features to …

What Users Say They Want In Documentation, David G. Novick, Karen Ward

David G. Novick

While earlier work provided a partial view of users’ preferences about manuals, for most users in most work contexts the important question remains open: What do users want in documentation? This paper presents the results of a study in which a diverse cross-section of 25 users was interviewed in depth about their needs and preferences with respect to software help systems, whether printed or on-line, that they use at work. The study’s participants indicated that they preferred documentation, whether online or printed, that is easy to navigate, provides explanations at an appropriate level of technical detail, enables finding as well …

Magnifying-Lens Abstraction For Markov Decision Processes, Luca De Alfaro, Pritam Roy

Luca de Alfaro

We present a novel abstraction technique which allows the analysis of reachability and safety properties of Markov decision processes with very large state spaces. The technique, called magnifying-lens abstraction, copes with the state-explosion problem by partitioning the state-space into regions, and by computing upper and lower bounds for reachability and safety properties on the regions, rather than on the states. To compute these bounds, magnifying-lens abstraction iterates over the regions, considering the concrete states of each region in turn, as if one were sliding across the abstraction a magnifying lens which allowed viewing the concrete states. The algorithm adaptively refines …

A Mathematical Regression Of The U.S. Gross Private Domestic Investment 1959-2001, Byron E. Bell

Byron E. Bell

SUMMARY OF PROJECT What did I do? A study of the role the U.S. stock markets and money markets have possibly played in the Gross Private Domestic Investment (GPDI) of the United States from the year 1959 to the year 2001 and I created a Multiple Linear Regression Model (MLRM).

Emisja Zanieczyszczeń Powietrza Z Procesu Grafityzacji Wyrobów Drobnych, Marian Mazur, Robert Oleniacz, Marek Bogacki, Przemysław Szczygłowski

Robert Oleniacz

The paper presents the research results of the air pollutant emissions from the graphitising process of fine carbon products in the Acheson furnace (discharge capacity 5,5 Mg). Research was performed for two kinds of raw material inputs (based on petroleum coke and pitch coke). Approximately 40-hours measurement series were carried out for each material including mainly such substances like carbon monoxide, hydrocarbons, nitrogen oxides, sulphur dioxide, hydrogen sulphide, carbon disulphide, ammonia, benzene, toluene, xylenes, total dust, tar substances and polycyclic aromatic hydrocarbons. Both average and maximum concentrations and mass streams in the flue gases and average emission factors were presented …

Sequences, Series, And Function Approximation, Lawrence Stout

Lawrence N. Stout

Sequences are important in approximation: the usual representation of real numbers using decimals is in fact the process of giving a sequence of rational numbers approximation the real number in question successively better as more decimal places are given. These decimal approximation sequences are actually rather special: successive decimal approximations never get smaller (so the sequence is monotone nondecreasing) and two approximations which agree to the kth decimal place differ by at most 10-k (so the sequence is a Cauchy sequence: to make two values in the sequence close to each other all you need to do is take them …

Reflections On Wallace, Charles H. Smith

Charles Kay Smith