Quantifying flow regimes in a Greenland glacial fjord using iceberg drifters

Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 41 (2014): 8411–8420, doi:10.1002/2014GL062256.Large, deep-keeled icebergs are ubiquitous in Greenland's outlet glacial fjords. Here we use the movement of these icebergs to quantify flow variability in Sermilik Fjord, southeast Greenland, from the ice mélange through the fjord to the shelf. In the ice mélange, a proglacial mixture of sea ice and icebergs, we find that icebergs consistently track the glacier speed, with slightly faster speeds near terminus and episodic increases due to calving events. In the fjord, icebergs accurately capture synoptic circulation driven by both along-fjord and along-shelf winds. Recirculation and in-/out-fjord variations occur throughout the fjord more frequently than previously reported, suggesting that across-fjord velocity gradients cannot be ignored. Once on the shelf, icebergs move southeastward in the East Greenland Coastal Current, providing wintertime observations of this freshwater pathway.Funding for this study was provided by National Science Foundation grants OCE-1130008 and ARC-0909274, and by the University of Oregon.2015-06-1

Quantifying flow regimes in a Greenland glacial fjord using iceberg drifters

Large, deep-keeled icebergs are ubiquitous in Greenland's outlet glacial fjords. Here we use the movement of these icebergs to quantify flow variability in Sermilik Fjord, southeast Greenland, from the ice mélange through the fjord to the shelf. In the ice mélange, a proglacial mixture of sea ice and icebergs, we find that icebergs consistently track the glacier speed, with slightly faster speeds near terminus and episodic increases due to calving events. In the fjord, icebergs accurately capture synoptic circulation driven by both along-fjord and along-shelf winds. Recirculation and in-/out-fjord variations occur throughout the fjord more frequently than previously reported, suggesting that across-fjord velocity gradients cannot be ignored. Once on the shelf, icebergs move southeastward in the East Greenland Coastal Current, providing wintertime observations of this freshwater pathway.Funded by The National Science Foundation. Grant Numbers: OCE-1130008, ARC-0909274 and The University of Oregon

The major allergens of birch pollen and cow milk, Bet v 1 and Bos d 5, are structurally related to human licocalin 2, enabling them to manipulate T-helper cells depending on their load with siderophore-bound iron

We conclude that Bet v 1 and Bos d 5 not only structurally mimic human LCN2, but also functionally by their ability to bind iron via siderophores. The apo-forms promote Th2 cells, whereas the holo-forms appear to be immunosuppressive. These results provide for the first time a functional understanding on the principle of allergenicity of major allergens from entirely independent sources, like birch and milk

An NDE Approach for Characterizing Quality Problems in Polymer Matrix Composites

Polymer matrix composite (PMC) materials are periodically identified appearing optically uniform but containing a higher than normal level of global nonuniformity as indicated from preliminary ultrasonic scanning. One such panel was thoroughly examined by nondestructive (NDE) and destructive methods to quantitatively characterize the nonuniformity. The NDE analysis of the panel was complicated by the fact that the panel was not uniformly thick. Mapping of ultrasonic velocity across a region of the panel in conjunction with an error analysis was necessary to (1) characterize properly the porosity gradient that was discovered during destructive analyses and (2) account for the thickness variation effects. Based on this study, a plan for future NDE characterization of PMC's is presented to the PMC community

Precision spectrophotometry for PNLF distances: the case of NGC 300

The Multi-Unit Spectroscopic Explorer (MUSE) has enabled a renaissance of the planetary nebula luminosity function (PNLF) as a standard candle. In the case of NGC 300, we learned that the precise spectrophotometry of MUSE was crucial to obtain an accurate PNLF distance. We present the advantage of the integral field spectrograph compared to the slit spectrograph in delivering precise spectrophotometry by simulating a slit observation on integral field spectroscopy data. We also discuss the possible systematic shift in measuring the PNLF distance using the least-square method, especially when the PNLF cutoff is affected by small number statistics.Comment: 5 pages, 4 figures, Submitted to the Proceedings of IAU Symposium 384: Planetary Nebulae: a Universal Toolbox in the Era of Precision Astrophysic

1964 soil fertility and plant nutrition research in southeast Missouri

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Operator projection method applied to the single-particle Green's function in the Hubbard model

A new non-perturbative framework for many-body correlated systems is formulated by extending the operator projection method (OPM). This method offers a systematic expansion which enables us to project into the low-energy structure after extracting the higher-energy hierarchy. This method also opens a way to systematically take into account the effects of collective excitations. The Mott-Hubbard metal-insulator transition in the Hubbard model is studied by means of this projection beyond the second order by taking into account magnetic and charge fluctuations in the presence of the high-energy Mott-Hubbard structure. At half filling, the Mott-Hubbard gap is correctly eproduced between the separated two bands. Near half filling, a strongly renormalized low-energy single-particle excitations coexisting with the Mott-Hubbard bands are shown to appear. Signifcance of momentum-dependent self-energy in the results is stressed.Comment: 6 pages, final version to appear in J. Phys. Soc. Jp

Competition between Magnetic and Structural Transition in CrN

CrN is observed to undergo a paramagnetic to antiferromagnetic transition accompanied by a shear distortion from cubic NaCl-type to orthorhombic structure. Our first-principle plane wave and ultrasoft pseudopotential calculations confirm that the distorted antiferromagnetic phase with spin configuration arranged in double ferromagnetic sheets along [110] is the most stable. Antiferromagnetic ordering leads to a large depletion of states around Fermi level, but it does not open a gap. Simultaneous occurence of structural distortion and antiferromagnetic order is analyzed.Comment: 10 pages, 10 figure

Anomalous Workfunction Anisotropy in Ternary Acetylides

Anomalous anisotropy of workfunction values in ternary alkali metal transition metal acetylides is reported. Workfunction values of some characteristic surfaces in these emerging semiconducting materials may differ by more than $\approx$ 2 eV as predicted by Density Functional Theory calculations. This large anisotropy is a consequence of the relative orientation of rod-like [MC$_{2}$]$_{\infty}$ negatively charged polymeric subunits and the surfaces, with M being a transition metal or metalloid element and C$_{2}$ refers to the acetylide ion C$_{2}^{2-}$, with the rods embedded into an alkali cation matrix. It is shown that the conversion of the seasoned Cs$_{2}$Te photo-emissive material to ternary acetylide Cs$_{2}$TeC$_{2}$ results in substantial reduction of its $\approx$ 3 eV workfunction down to 1.71-2.44 eV on the Cs$_{2}$TeC$_{2}$(010) surface while its high quantum yield is preserved. Similar low workfunction values are predicted for other ternary acetylides as well, allowing for a broad range of applications from improved electron- and light-sources to solar cells, field emission displays, detectors and scanners.Comment: Accepted for publication in Phys. Rev.