Emerging wetlands from river diversions can sustain high denitrification rates in a Coastal Delta

Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Biogeosciences 126(5), (2021): e2020JG006217, https://doi.org/10.1029/2020JG006217.It is assumed that to treat excess NO3− high soil organic matter content (%OM) is required to maintain high denitrification rates in natural or restored wetlands. However, this excess also represents a risk by increasing soil decomposition rates triggering peat collapse and wetland fragmentation. Here, we evaluated the role of %OM and temperature interactions controlling denitrification rates in eroding (Barataria Bay-BLC) and emerging (Wax Lake Delta-WLD) deltaic regions in coastal Louisiana using the isotope pairing (IPT) and N2:Ar techniques. We also assessed differences between total (direct denitrification + coupled nitrification-denitrification) and net (total denitrification minus nitrogen fixation) denitrification rates in benthic and wetland habitats with contrasting %OM and bulk density (BD). Sediment (benthic) and soil (wetland) cores were collected during summer, spring, and winter (2015–2016) and incubated at close to in-situ temperatures (30°C, 20°C, and 10°C, respectively). Denitrification rates were linearly correlated with temperature; maximum mean rates ranged from 40.1–124.1 μmol m−2 h−1 in the summer with lower rates (30 μM) and water temperature is >10°C. In coastal Louisiana, substrates under these regimes are represented by emergent supra-tidal flats or land created by sediment diversions under oligohaline conditions (<1 ppt).This study was supported by the NOAA-Sea Grant Program-Louisiana (Grant 2013R/E-24) to Victor H. Rivera-Monroy and Kanchan Maiti. Victor H. Rivera-Monroy was also supported by the Department of the Interior South-Central Climate Adaptation Science Center (Cooperative Agreement #G12AC00002)

Stabilization of single-electron pumps by high magnetic fields

We study the effect of perpendicular magnetic fields on a single-electron system with a strongly time-dependent electrostatic potential. Continuous improvements to the current quantization in these electron pumps are revealed by high-resolution measurements. Simulations show that the sensitivity of tunnel rates to the barrier potential is enhanced, stabilizing particular charge states. Nonadiabatic excitations are also suppressed due to a reduced sensitivity of the Fock-Darwin states to electrostatic potential. The combination of these effects leads to significantly more accurate current quantization

Immunolocalization of KATP channel subunits in mouse and rat cardiac myocytes and the coronary vasculature.

BACKGROUND: Electrophysiological data suggest that cardiac KATP channels consist of Kir6.2 and SUR2A subunits, but the distribution of these (and other KATP channel subunits) is poorly defined. We examined the localization of each of the KATP channel subunits in the mouse and rat heart. RESULTS: Immunohistochemistry of cardiac cryosections demonstrate Kir6.1 protein to be expressed in ventricular myocytes, as well as in the smooth muscle and endothelial cells of coronary resistance vessels. Endothelial capillaries also stained positive for Kir6.1 protein. Kir6.2 protein expression was found predominantly in ventricular myocytes and also in endothelial cells, but not in smooth muscle cells. SUR1 subunits are strongly expressed at the sarcolemmal surface of ventricular myocytes (but not in the coronary vasculature), whereas SUR2 protein was found to be localized predominantly in cardiac myocytes and coronary vessels (mostly in smaller vessels). Immunocytochemistry of isolated ventricular myocytes shows co-localization of Kir6.2 and SUR2 proteins in a striated sarcomeric pattern, suggesting t-tubular expression of these proteins. Both Kir6.1 and SUR1 subunits were found to express strongly at the sarcolemma. The role(s) of these subunits in cardiomyocytes remain to be defined and may require a reassessment of the molecular nature of ventricular KATP channels. CONCLUSIONS: Collectively, our data demonstrate unique cellular and subcellular KATP channel subunit expression patterns in the heart. These results suggest distinct roles for KATP channel subunits in diverse cardiac structures

The discovery of polarization in the afterglow of GRB 990510 with the ESO Very Large Telescope

Following a BeppoSAX alert (Piro 1999a) and the discovery of the OT at SAAO (Vreeswijk et al. 1999a), we observed GRB 990510 with the FORS instrument on ESO's VLT Unit 1 (`Antu'). The burst is unremarkable in gamma rays, but in optical is the first one to show good evidence for jet-like outflow (Stanek et al. 1999, Harrison et al. 1999). We report the detection of significant linear polarization in the afterglow: it is (1.6 +/- 0.2)% 0.86 days after trigger, and after 1.81 days is consistent with that same value, but much more uncertain. The polarization angle is constant on a time scale of hours, and may be constant over one day. We conclude that the polarization is intrinsic to the source and due to the synchrotron nature of the emission, and discuss the random and ordered field geometries that may be responsible for it.Comment: submitted to ApJ Lett., 5 pages including 2 figures, uses emulateapj.st

Metastable and localized Ising magnetism in α−CoV2O6 magnetization plateaus

$\alpha$-CoV$_{2}$O$_{6}$ consists of $j_{\mathrm{eff}}={1 \over 2}$ Ising spins located on an anisotropic triangular motif with magnetization plateaus in an applied field. We combine neutron diffraction with low temperature magnetization to investigate the magnetic periodicity in the vicinity of these plateaus. We find these steps to be characterized by metastable and spatially short-range ($\xi\sim$ 10 $\r{A}$) magnetic correlations with antiphase boundaries defining a local periodicity of $\langle \hat{T}^{2} \rangle =\ \uparrow \downarrow$to$\langle \hat{T}^{3} \rangle =\ \uparrow \uparrow \downarrow$, and$\langle \hat{T}^{4} \rangle=\ \uparrow \uparrow \downarrow \downarrow$or$\uparrow \uparrow \uparrow \downarrow$ spin arrangements. This shows the presence of spatially short range and metastable/hysteretic, commensurate magnetism in Ising magnetization steps.Comment: 9 pages, 6 figures, to be published in Phys. Rev.

Swift captures the spectrally evolving prompt emission of GRB 070616

The origins of Gamma-ray Burst prompt emission are currently not well understood and in this context long, well-observed events are particularly important to study. We present the case of GRB 070616, analysing the exceptionally long-duration multipeaked prompt emission, and later afterglow, captured by all the instruments on-board Swift and by Suzaku WAM. The high energy light curve remained generally flat for several hundred seconds before going into a steep decline. Spectral evolution from hard to soft is clearly taking place throughout the prompt emission, beginning at 285 s after the trigger and extending to 1200 s. We track the movement of the spectral peak energy, whilst observing a softening of the low energy spectral slope. The steep decline in flux may be caused by a combination of this strong spectral evolution and the curvature effect. We investigate origins for the spectral evolution, ruling out a superposition of two power laws and considering instead an additional component dominant during the late prompt emission. We also discuss origins for the early optical emission and the physics of the afterglow. The case of GRB 070616 clearly demonstrates that both broadband coverage and good time resolution are crucial to pin down the origins of the complex prompt emission in GRBs.Comment: 13 pages, 11 figures (2 in colour), MNRAS accepte

Ghrelińs Orexigenic Effect Is Modulated via a Serotonin 2C Receptor Interaction

Understanding the intricate pathways that modulate appetite and subsequent food intake is of particular importance considering the rise in the incidence of obesity across the globe. The serotonergic system, specifically the 5-HT2C receptor, has been shown to be of critical importance in the regulation of appetite and satiety. The GHS-R1a receptor is another key receptor that is well-known for its role in the homeostatic control of food intake and energy balance. We recently showed compelling evidence for an interaction between the GHS-R1a receptor and the 5-HT2C receptor in an in vitro cell line system heterologously expressing both receptors. Here, we investigated this interaction further. First, we show that the GHS-R1a/5-HT2C dimer-induced attenuation of calcium signaling is not due to coupling to GαS, as no increase in cAMP signaling is observed. Next, flow cytometry fluorescence resonance energy transfer (fcFRET) is used to further demonstrate the direct interaction between the GHS-R1a receptor and 5-HT2C receptor. In addition, we demonstrate colocalized expression of the 5-HT2C and GHS-R1a receptor in cultured primary hypothalamic and hippocampal rat neurons, supporting the biological relevance of a physiological interaction. Furthermore, we demonstrate that when 5-HT2C receptor signaling is blocked ghreliņs orexigenic effect is potentiated in vivo. In contrast, the specific 5-HT2C receptor agonist lorcaserin, recently approved for the treatment of obesity, attenuates ghrelin-induced food intake. This underscores the biological significance of our in vitro findings of 5-HT2C receptor-mediated attenuation of GHS-R1a receptor activity. Together, this study demonstrates, for the first time, that the GHS-R1a/5-HT2C receptor interaction translates into a biologically significant modulation of ghreliņs orexigenic effect. This data highlights the potential development of a combined GHS-R1a and 5-HT2C receptor treatment strategy in weight management.Instituto Multidisciplinario de Biología Celula

Dark Heritage

Peer reviewe

Partitioning of on-demand electron pairs

We demonstrate the high fidelity splitting of electron pairs emitted on demand from a dynamic quantum dot by an electronic beam splitter. The fidelity of pair splitting is inferred from the coincidence of arrival in two detector paths probed by a measurement of the partitioning noise. The emission characteristic of the on-demand electron source is tunable from electrons being partitioned equally and independently to electron pairs being split with a fidelity of 90%. For low beam splitter transmittance we further find evidence of pair bunching violating statistical expectations for independent fermions