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Factors influencing American Pika (Ochotona princeps) distributions in the Beartooth Mountains and implications of a warming climate
No full textOver the next century, temperatures are expected to rise by 1-4°C in the Greater Yellowstone Region. This will force alpine species such as the American pika (Ochotona princeps) to compensate, shift in distribution, or disappear. If pika are limited by temperatures, they may disappear from warmer, lower elevation southwest-facing sites and find refuge in cooler, higher elevation northeast-facing sites. However, populations have been found across a range of elevations, suggesting they are instead limited by food or a need for large talus slopes. We explored these possibilities in the Beartooth Mountains, near Yellowstone, by surveying 31 pika populations and asking whether pika density varied with elevation, food availability, or aspect, all related to temperatures, or with talus area, which is not. Pika density was estimated by latrine density, which ranged from 14.6 to 167.4 per ha and declined slightly with elevation but was unrelated to vegetation. From a preliminary analysis of 61 sites, we estimated an occupancy probability of 0.89, with occupancy most strongly related to talus area. We will test and refine these results by predicting the locations of additional colonies, and by incorporating microclimate data into an ecophysiological model of temperature dependence in pika, with the long-term goal of predicting the fate of pika under a warming climate.
Featured photo by Diana R on Unsplash. https://unsplash.com/photos/g6CD00mDN5A 
Potentially nilpotent tridiagonal sign patterns of order 4
No full textAn sign pattern is said to be potentially nilpotent (PN) if there exists some nilpotent real matrix with sign pattern . In [M.~Arav, F.~Hall, Z.~Li, K.~Kaphle, and N.~Manzagol.Spectrally arbitrary tree sign patterns of order , {\em Electronic Journal of Linear Algebra}, 20:180--197, 2010.], the authors gave some open questions, and one of them is the following: {\em For the class of tridiagonal sign patterns, is PN (together with positive and negative diagonal entries) equivalent to being SAP?}\ In this paper, a positive answer for this question is given
Spatio-temporal ecological and evolutionary dynamics in natural butterfly populations
No full textSpatial and temporal variation in the strength and nature of natural selection could help explain genetic diversity in natural populations and data on short term evolutionary responses to fluctuations in temperature and rainfall could facilitate predictions of climate change impacts. In 2012, we began a long term study of genome-wide molecular evolution in populations of Lycaeides idas in the Greater Yellowstone Ecosystem (GYE). In 2016, we used distance sampling to estimate population densities of 10 butterfly populations spread across the GYE in Wyoming and Montana. In parallel, we estimated host plant cover and conducted insect community surveys at each site. We also completed a genotyping-by-sequencing survey for eight populations sampled in 2013 and 2015 to estimate contemporary variance in effective population sizes. Based on 480 samples across sites, we found significant variation in population sizes (as estimated by distance sampling) among sites and years. Host plant abundance, climate, and insect communities varied among sites but were not consistently predictive of population size. Estimates of effective population sizes among sites showed pronounced variation that was uncorrelated with genetic diversity, possibly due to widespread fluctuating selection.
Featured photo from Figure 1 in report
Using LiDAR imagery to locate historic-era homesteads and irrigation features of the Mormon Row, Antelope Flats, and dry farms historic landscapes, Grand Teton National Park, Teton County, Wyoming
No full textGIS analysis of LiDAR imagery facilitated a modified NHPA Section 110 Class II survey and inventory performed in the summer of 2016 resulting in the identification of hundreds of fragmentary, relict, and extant cultural resources located in the vicinity of the Mormon Row Historic District (MRHD; 48TE1444) between June 6 and August 10, 2016. Correct identification and association of newly located cultural resources with persons, historic-era homesteads, and historic events is a complex and lengthy process requiring thorough artifact analysis and substantial background, ethnologic, and archival (contextual) research to make recommendations of significance, eligibility, and/or inclusion as contributing elements or not to the MRHD. Moving from the artifact scale to the site, feature, or historic district scale is a scalar process. Once at the site or historic district scale, it may be appropriate to ask whether the cultural resources can be addressed at a landscape scale, and ask new research questions such as: What if one were to consider all the cultural resources–prehistoric, historic, and natural–together? Are there theories and/or methodologies that can accommodate multiple layers of cultural resources and time frames and result in interpretations that are meaningful for present and future cultural resources management praxis?
Featured photo by Tim Peterson on Unsplash. https://unsplash.com/photos/Ab6ksdu5Q7
On the distance from a weakly normal matrix polynomial to matrix polynomials with a prescribed multiple eigenvalue
No full textConsider an$n\times n matrix polynomial P(\lambda). An upper bound for a spectral norm distance from P(\lambda) to the set of n \times n matrix polynomials that have a given scalar μ in C as a multiple eigenvalue was obtained by Papathanasiou and Psarrakos (2008). This paper concerns a refinement of this result for the case of weakly normal matrix polynomials. A modified method is developed and its efficiency is verified by two illustrative examples. The proposed methodology can also be applied to general matrix polynomials
On the amplitude and phase response in the non-abelian Fourier transform
No full textIn the context of the non-abelian Fourier transform, the natural extension of the amplitude and phase response to a convolution by a given filter mask are shown to be the polar decompositions of the Fourier transform matrices. A specific example regarding amplitude and phase response of a certain filter mask over the symmetric group S_3 is given
Totally Positive Density Matrices and Linear Preservers
No full textThe intersection between the set of totally nonnegative matrices, which are of interest in many areas of matrix theory and its applications, and the set of density matrices, which provide the mathematical description of quantum states, are investigated. The single qubit case is characterized, and several equivalent conditions for a quantum channel to preserve the set in that case are given. Higher dimensional cases are also discussed
An iterative method to solve a nonlinear matrix equation
No full textn this paper, an iterative method to solve one kind of nonlinear matrix equation is discussed. For each initial matrix with some conditions, the matrix sequences generated by the iterative method are shown to lie in a fixed open ball. The matrix sequences generated by the iterative method are shown to converge to the only solution of the nonlinear matrix equation in the fixed closed ball. In addition, the error estimate of the approximate solution in the fixed closed ball, and a numerical example to illustrate the convergence results are given
Group inverse extensions of certain -matrix properties
No full textIn this article, generalizations of certain -matrix properties are proved for the group generalized inverse. The proofs use the notion of proper splittings of one type or the other. In deriving certain results, we make use of a recently introduced notion of a -splitting. Applications in obtaining comparison results for the spectral radii of matrices are presented