The vertical distribution of iron stable isotopes in the North Atlantic near Bermuda

Seawater dissolved iron isotope ratios (δ^(56)Fe) have been measured in the North Atlantic near Bermuda. In a full-depth profile, seawater dissolved δ^(56)Fe is isotopically heavy compared to crustal values throughout the water column (δ^(56)Fe_(IRMM-014) = +0.30‰ to +0.71‰). Iron isotope ratios are relatively homogenous in the upper water column (between +0.30‰ to +0.45‰ above 1500 m), and δ^(56)Fe increases below this to a maximum of +0.71‰ at 2500 m, decreasing again to +0.35‰ at 4200 m. The δ^(56)Fe profile is very different from the iron concentration profile; in the upper water column [Fe] is variable while δ^(56)Fe is relatively constant, and in the deeper water column δ^(56)Fe varies while [Fe] remains relatively constant. The δ^(56)Fe profile is also not well correlated with other hydrographic tracers in the North Atlantic such as temperature, salinity, or the concentrations of oxygen, phosphate, silica, and CFC-11. The dissimilarity between δ^(56)Fe profiles and profiles of [Fe] and other hydrographic tracers shows that Fe isotope ratios provide a unique sort of information about ocean chemistry, and they suggest that Fe isotopes may therefore be a valuable new tool for tracing the global sources, sinks, and biogeochemical cycling of Fe

MHD wave modes resolved in fine-scale chromospheric magnetic structures

Within the last decade, due to significant improvements in the spatial and temporal resolution of chromospheric data, magnetohydrodynamic (MHD) wave studies in this fascinating region of the Sun's atmosphere have risen to the forefront of solar physics research. In this review we begin by reviewing the challenges and debates that have manifested in relation to MHD wave mode identification in fine-scale chromospheric magnetic structures, including spicules, fibrils and mottles. Next we go on to discuss how the process of accurately identifying MHD wave modes also has a crucial role to play in estimating their wave energy flux. This is of cardinal importance for estimating what the possible contribution of MHD waves is to solar atmospheric heating. Finally, we detail how such advances in chromospheric MHD wave studies have also allowed us, for the first time, to implement cutting-edge magnetoseismological techniques that provide new insight into the sub-resolution plasma structuring of the lower solar atmosphere.Comment: 16 pages, 6 figures, to appear as a chapter in the upcoming AGU/Wiley book "Low-frequency Waves in Space Plasmas

Every Hilbert space frame has a Naimark complement

Naimark complements for Hilbert space Parseval frames are one of the most fundamental and useful results in the field of frame theory. We will show that actually all Hilbert space frames have Naimark complements which possess all the usual properties for Naimark complements with one notable exception. So these complements can be used for equiangular frames, RIP property, fusion frames etc. Along the way, we will correct a mistake in a recent fusion frame paper where chordal distances for Naimark complements are computed incorrectly.Comment: Changes after Refereein

Every Hilbert space frame has a Naimark complement

Naimark complements for Hilbert space Parseval frames are one of the most fundamental and useful results in the field of frame theory. We will show that actually all Hilbert space frames have Naimark complements which possess all the usual properties for Naimark complements with one notable exception. So these complements can be used for equiangular frames, RIP property, fusion frames etc. Along the way, we will correct a mistake in a recent fusion frame paper where chordal distances for Naimark complements are computed incorrectly.Comment: Changes after Refereein

Solar feature tracking in both spatial and temporal domains

A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. The reliability of this technique was tested with TRACE 171A observations. The application of this technique to a flare-induced kink-mode oscillation, revealed a 3500 km spatial periodicity which occur along the loop edge. We establish a reduction in oscillatory power, for these spatial periodicities, of 45% over a 322 s interval. We relate the reduction in oscillatory power to the physical damping of these loop-top oscillations

Squaring an Open Circle: Trends and Opportunities in Open Access Publishing, Promotion, and Impact

This poster will examine the trends surrounding scholarly communications amongst faculty authors at UTHSC to determine prevalence of Open Access (OA) publishing in order to formulate a strategy for the library to reallocate services and funds to meet the changing needs of the Library’s users. Using bibliographic analysis and citation analysis for the prior 10 years (2009-2018), we hope to discover the following: the trend with respect to OA publishing amongst UTHSC faculty including the difference between Gold OA and Green OA; the specific journals in which UTHSC faculty choose to publish; and, the impact of OA publishing versus traditional models with respect to citations. Using filters built into the Web of Science database, the authors were able to isolate OA articles authored by UTHSC affiliated faculty. Citations in which a UTHSC affiliated author is listed as the corresponding author were included in the OA results. The resulting citations were grouped by year of publication and Gold/Green OA to determine potential growth trends. Further, Gold OA results were filtered by journal title to determine in which journals faculty were publishing. Finally, the OA output was compared with non-OA results from the same period to determine what, if any, impact OA had on impact of the scholarship with respect to citations

The magnetic structure of the zigzagzigzag chain family Nax_{x}Ca1−x_{1-x}V2_2O4_4 determined by muon-spin rotation

We present muon-spin rotation measurements on polycrystalline samples of the complete family of the antiferromagnetic (AF) $zigzag$ chain compounds, Na$_x$Ca$_{1-x}$V$_2$O$_4$. In this family, we explore the magnetic properties from the metallic NaV$_2$O$_4$ to the insulating CaV$_2$O$_4$. We find a critical $x_c(\sim0.833)$ which separates the low and high Na-concentration dependent transition temperature and its magnetic ground state. In the $x<x_c$ compounds, the magnetic ordered phase is characterized by a single homogenous phase and the formation of incommensurate spin-density-wave order. Whereas in the $x>x_c$ compounds, multiple sub-phases appear with temperature and $x$. Based on the muon data obtained in zero external magnetic field, a careful dipolar field simulation was able to reproduce the muon behavior and indicates a modulated helical incommensurate spin structure of the metallic AF phase. The incommensurate modulation period obtained by the simulation agrees with that determined by neutron diffraction.Comment: 7 pages, 7 figures, accepted for publication in PR