Brassinosteroids (
In this study, we numerically investigate the transport properties of a two‐dimensional (
- NSF-PAR ID:
- 10049001
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Contributions to Plasma Physics
- Volume:
- 58
- Issue:
- 2-3
- ISSN:
- 0863-1042
- Page Range / eLocation ID:
- p. 209-216
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Rationale Nitrogen stable isotope ratio (δ15N) processes are not well described in reptiles, which limits reliable inference of trophic and nutrient dynamics. In this study we detailed δ15N turnover and discrimination (Δ15N) in diverse tissues of two lizard species, and compared these results with previously published carbon data (δ13C) to inform estimates of reptilian foraging ecology and nutrient physiology.
Methods We quantified15N incorporation and discrimination dynamics over 360 days in blood fractions, skin, muscle, and liver of
andSceloporus undulatus that differed in body mass. Tissue samples were analyzed on a continuous flow isotope ratio mass spectrometer.Crotaphytus collaris Results Δ15N for plasma and red blood cells (RBCs) ranged between +2.7 and +3.5‰; however, skin, muscle, and liver did not equilibrate, hindering estimates for these somatic tissues.15N turnover in plasma and RBCs ranged from 20.7 ± 4 to 303 ± 166 days among both species. Comparison with previously published δ13C results for these same samples showed that15N and13C incorporation patterns were uncoupled, especially during winter when hibernation physiology could have played a role.
Conclusions Our results provide estimates of15N turnover rates and discrimination values that are essential to using and interpreting isotopes in studies of diet reconstruction, nutrient allocation, and trophic characterization in reptiles. These results also suggest that somatic tissues can be unreliable, while life history shifts in nutrient routing and metabolism potentially cause15N and13C dynamics to be decoupled.
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Abstract RF coil design for human ultra‐high field (7 T and higher) magnetic resonance (MR ) imaging is an area of intense development, to overcome difficult challenges such asRF excitation spatial heterogeneity and lowRF transfer efficiency into the spin system. This article proposes a novel category of multi‐channelRF volume coil structures at both 7 T and 10.5 T based on a subject‐loaded multifilar helical‐antennaRF coil that aims at addressing these problems. In some prior applications of helix antennas asMR RF coils at 7 T, the imaged sample was positioned outside the helix. Here, we introduce a radically different approach, with the inner volume of a helix antenna being utilized to image a sample. The new coil uniquely combines traveling‐wave behavior through the overall antenna wire structure and near‐fieldRF interaction between the conducting elements and the imaged tissues. It thus benefits from the congruence of far‐ and near‐field regimes. Design and analysis of the novel inner‐volume coils are performed by numerical simulations using multiple computational electromagnetics techniques. The fabricated coil prototypes are tested, validated, and evaluated experimentally in 7‐T and 10.5‐TMR human wide bore (90‐cm) MR scanners. Phantom data at 7 T show good consistency between numerical simulations and experimental results. SimulatedB 1+transmit efficiencies, in T/√W, are comparable to those of some of the conventional and state‐of‐the‐artRF coil designs at 7 T. Experimental results at 10.5 T show the scalability of the helix coil design. -
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