D. Barnhill
A5034509325- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- Polynomial and algebraic computation
- Particle Detector Development and Performance
- Computational Geometry and Mesh Generation
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Photocathodes and Microchannel Plates
- Topological and Geometric Data Analysis
- Particle Accelerators and Free-Electron Lasers
- Genetic diversity and population structure
- Advanced Numerical Analysis Techniques
- Data Management and Algorithms
- Adaptive optics and wavefront sensing
- Soil Geostatistics and Mapping
- Astronomical Observations and Instrumentation
- Muon and positron interactions and applications
- Particle physics theoretical and experimental studies
- Spacecraft Design and Technology
- Environmental Monitoring and Data Management
- Radio Astronomy Observations and Technology
- Bayesian Modeling and Causal Inference
- Internet Traffic Analysis and Secure E-voting
- Ecocriticism and Environmental Literature
United States Naval Academy
2024
Naval Postgraduate School
2023-2024
University of California, Los Angeles
2003-2008
Pierre Auger Observatory
2007
Universidade Federal Fluminense
2007
Comisión Nacional de Energía Atómica
2005
Using data collected at the Pierre Auger Observatory during past 3.7 years, we demonstrated a correlation between arrival directions of cosmic rays with energy above 6 × 10 19 electron volts and positions active galactic nuclei (AGN) lying within ∼75 megaparsecs. We rejected hypothesis an isotropic distribution these least 99% confidence level from prescribed priori test. The observed is compatible that highest-energy particles originate nearby extragalactic sources whose flux has not been...
The energy spectrum of cosmic rays above 2.5 x 10;{18} eV, derived from 20,000 events recorded at the Pierre Auger Observatory, is described. spectral index gamma particle flux, J proportional, variantE;{-gamma}, energies between 4 eV and 10;{19} 2.69+/-0.02(stat)+/-0.06(syst), steepening to 4.2+/-0.4(stat)+/-0.06(syst) higher energies. hypothesis a single power law rejected with significance greater than 6 standard deviations. data are consistent prediction by Greisen Zatsepin Kuz'min.
The surface detector array of the Pierre Auger Observatory is sensitive to Earth-skimming tau neutrinos that interact in Earth's crust. Tau leptons from ${\ensuremath{\nu}}_{\ensuremath{\tau}}$ charged-current interactions can emerge and decay atmosphere produce a nearly horizontal shower with significant electromagnetic component. data collected between 1 January 2004 31 August 2007 are used place an upper limit on diffuse flux at EeV energies. Assuming...
Much evidence from biological theory and empirical data indicates that, gene trees, phylogenetic trees reconstructed different genes (loci), do not have to exactly the same tree topologies. Such incongruence between might be caused by some "unusual" evolutionary events, such as meiotic sexual recombination in eukaryotes or horizontal transfers of genetic material prokaryotes. However, most are constrained topology underlying species tree, that is, depicting history set under consideration....
In this paper, we propose clustering methods for use on data described as tropically convex. Our approach is similar to used in the Euclidean space, where identify groupings of observations using tropical analogs K-means and hierarchical space. We provide results from computational experiments generic simulated well an application phylogeny ultrametrics, demonstrating efficacy these methods.
In this paper we propose Hit and Run (HAR) sampling from a tropically convex set.The key ingredient of HAR set is uniformly tropical line segment over the projective torus, which runs linearly in its computational time complexity.We show that method samples polytope smallest finitely many vertices.Finally, apply novel to any given distribution using Metropolis-Hasting filtering polytope.
Journal Article Surveying the Landscape: A New Approach to Nature Writing Get access David Landis Barnhill barnhill@uwosh.edu Search for other works by this author on: Oxford Academic Google Scholar ISLE: Interdisciplinary Studies in Literature and Environment, Volume 17, Issue 2, Spring 2010, Pages 273–290, https://doi.org/10.1093/isle/isq028 Published: 21 April 2010
The Pierre Auger Observatory is being used to study cosmic rays with energies larger than 10 EeV. An essential quantity that must be deduced from data the lateral distribution function (LDF). Knowledge of LDF important for reconstruction shower core and direction. Here we describe how measured using large sample events recorded surface detector (SD) array a small observed fluorescence detectors (FD). For hybrid events, in which SD FD measurements same are available, position much better...
We consider a minimum enclosing and maximum inscribed tropical balls for any given polytope over the projective torus in terms of metric with max-plus algebra. show that we can obtain such via linear programming. Then apply to estimate volume sample uniformly from polytope.
We study the geometry of tropical Fermat-Weber points in terms symmetric metric over projective torus. It is well known that a point given sample not unique and this paper we show set all possible forms polytrope. Then, introduce gradient using them, polytrope bounded cell hyperplane arrangement by both min- max-tropical hyperplanes with apices which are observations input data.
This note introduces the $\texttt{LikelihoodGeometry}$ package for computer algebra system $\textit{Macaulay2}$. gives tools to construct likelihood correspondence of a discrete algebraic statistical model, variety that ties together data and their maximum estimators. includes methods constructing combining popular models calculating ML-degree.