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Potentially Eventually Positive 2-generalized Star Sign Patterns
No full textA sign pattern is a matrix whose entries belong to the set . An -by- sign pattern is said to be potentially eventually positive if there exists at least one real matrix with the same sign pattern as and a positive integer such that A^{k}>0 for all . An -by- sign pattern is said to be potentially eventually exponentially positive if there exists at least one real matrix with the same sign pattern as and a nonnegative integer such that e^{tA}=\sum_{k=0}^{\infty}\frac{t^{k}A^{k}}{k!}>0 for all . Identifying necessary and sufficient conditions for an -by- sign pattern to be potentially eventually positive (respectively, potentially eventually exponentially positive), and classifying these sign patterns are open problems. In this article, the potential eventual positivity of the -generalized star sign patterns is investigated. All the minimal potentially eventually positive -generalized star sign patterns are identified. Consequently, all the potentially eventually positive -generalized star sign patterns are classified. As an application, all the minimal potentially eventually exponentially positive -generalized star sign patterns are identified. Consequently, all the potentially eventually exponentially positive -generalized star sign patterns are classified
Pairwise Completely Positive Matrices and Conjugate Local Diagonal Unitary Invariant Quantum States
No full textA generalization of the set of completely positive matrices called pairwise completely positive (PCP) matrices is introduced. These are pairs of matrices that share a joint decomposition so that one of them is necessarily positive semidefinite while the other one is necessarily entrywise non-negative. Basic properties of these matrix pairs are explored and several testable necessary and sufficient conditions are developed to help determine whether or not a pair is PCP. A connection with quantum entanglement is established by showing that determining whether or not a pair of matrices is pairwise completely positive is equivalent to determining whether or not a certain type of quantum state, called a conjugate local diagonal unitary invariant state, is separable. Many of the most important quantum states in entanglement theory are of this type, including isotropic states, mixed Dicke states (up to partial transposition), and maximally correlated states. As a specific application of these results, a wide family of states that have absolutely positive partial transpose are shown to in fact be separable
On Orthogonal Matrices with Zero Diagonal
No full textThis paper considers real orthogonal matrices whose diagonal entries are zero and off-diagonal entries nonzero, which are referred to as \OMZD(n). It is shown that there exists an \OMZD(n) if and only if , and that a symmetric \OMZD(n) exists if and only if is even and . Also, a construction of \OMZD(n) obtained from doubly regular tournaments is given. Finally, the results are applied to determine the minimum number of distinct eigenvalues of matrices associated with some families of graphs, and the related notion of orthogonal matrices with partially-zero diagonal is considered
Maps Preserving Norms of Generalized Weighted Quasi-arithmetic Means of Invertible Positive Operators
No full textIn this paper, the problem of describing the structure of transformations leaving norms of generalized weighted quasi-arithmetic means of invertible positive operators invariant is discussed. In a former result of the authors, this problem was solved for weighted quasi-arithmetic means, and here the corresponding result is generalized by establishing its solution under certain mild conditions. It is proved that in a quite general setting, generalized weighted quasi-arithmetic means on self-adjoint operators are not monotone in their variables which is an interesting property. Moreover, the relation of these means with the Kubo-Ando means is investigated and it is shown that the common members of the classes of these types of means are weighted arithmetic means
Balay, Anne (2018) Semi Queer: Inside the World of Gay, Trans, and Black Truck Drivers, The University of North Carolina Press, Chapel Hill, NC.
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The Yellowstone magmatic-hydrothermal system: using radiogenic and stable isotope geochemistry to constrain the processes of water-rock interaction
No full textThe hot springs of Yellowstone National Park provide a broad range of isotopic data (e.g. 238U-, 235U-, and 232Th-series) that can be exploited to interpret the geochemical processes occurring at depth, including water-rock interaction, nuclide sourcing, and fluid residence times. Despite its worldwide notoriety, Yellowstone’s hydrothermal system remains largely unconstrained. While major advances in the past century have helped us to understand the highly varied geochemical characteristics of Yellowstone’s thermal features and their potential mechanisms of formation, many questions remain regarding where exactly the water resides before ascending to the surface, how long the water remains at depth, and what geochemical processes are occurring between these waters and the superheated aquifer rocks. One of the primary questions surrounding the Yellowstone hydrothermal system revolves around the concept of “phase separation”, whereby ascending, pressurized hydrothermal fluids undergo decompressional boiling and separate into an acidic vapor phase and a neutral fluid phase. These diverging phases result in the two dominant spring chemistries viewed on the surface, acid-sulfate springs and neutral-chloride springs. Still, little is known about the timescales such a process operates on, and what geochemical parameters can be constrained to support the existence of this model. Herein we examine a handful of hydrothermal features throughout Yellowstone National Park in an effort to investigate the likelihood of phase separation’s existence and whether or not the isotopic evidence supports the geochemical processes that we know to be occurring should this model persist within the plumbing of a continental hydrothermal system.
Featured photo from figure 3 in report. 
For everything there was a season: phenological shifts in the Tetons ecosystem
No full textPhenology — the timing of ecological events — is shifting as the climate warms. Grand Teton National Park biologists have identified this topic (“effect of earlier plant flowering on pollinators and wildlife”) as one of their priority research needs. To address this, we assembled phenological observations of first flowering dates for 48 species collected by Frank Craighead, Jr. in the 1970 and 80s. We hypothesized many species would be flowering earlier now. In 2016 we began standardized observations in the same locations targeting the same species plus 62 for a total of 110. We compare four years of contemporary to historic observations to demonstrate shifts in phenology, and use local weather data to identify the key climatic drivers. The largest effect is observed in early spring flowers, which are blooming ~17 days earlier. Mid-summer flowers bloom ~12 days earlier, and berries bloom ~7 days earlier. Not all species are emerging earlier, particularly late summer flowering plants. Also individual species within these functional groups differ in their responses. The greatest drivers of early spring and mid-summer flowering are average spring temperature (March, April, May) and the day of snow melt timing. Late summer flowers respond more to the accumulation of Growing Degree Days.
Featured photo by Shawna Wolf, taken from the AMK Ranch photo collection
Pure PSVD approach to Sylvester-type quaternion matrix equations
No full textIn this paper, the pure product singular value decomposition (PSVD) for four quaternion matrices is given. The system of coupled Sylvester-type quaternion matrix equations with five unknowns is considered by using the PSVD approach, where and are given quaternion matrices of compatible sizes . Some necessary and sufficient conditions for the existence of a solution to this system are derived. Moreover, the general solution to this system is presented when it is solvable
More than a ‘Curious Cultural Sideshow’: Samuel Slater's Sunday School and the Role of Literacy Sponsorship in Disciplining Labor
No full textThis article investigates the concept of literacy sponsorship through the introduction of textile factories and mill villages in New England during the American Industrial Revolution. Specifically, the article focuses on Samuel Slater’s mill villages and his disciplining and socialization of workers via the ‘family’ approach to factory production, and, in particular, his support of the Sunday school. As an institution key to managerial control and new to rural New England, the Sunday school captures the complicated networks of moral and literacy sponsorship in the transition to factory production