High daily energy expenditure of incubating shorebirds on High Arctic tundra: a circumpolar study

1. Given the allometric scaling of thermoregulatory capacity in birds, and the cold and exposed Arctic environment, it was predicted that Arctic-breeding shorebirds should incur high costs during incubation. Using doubly labelled water (DLW), daily energy expenditure (DEE) during incubation was measured in eight shorebird species weighing between 29 and 142 g at various sites in the Eurasian and Canadian High Arctic. The results are compared with a compilation of similar data for birds at lower latitudes. 2. There was a significant positive correlation between species average DEE and body mass (DEE (kJ day−1) = 28·12 BM (g)^0·524, r^2 = 0·90). The slopes of the allometric regression lines for DEE on body mass of tundra-breeding birds and lower latitude species (a sample mostly of passerines but including several shorebirds) are similar (0·548 vs 0·545). DEE is about 50% higher in birds on the tundra than in temperate breeding areas. 3. Data for radiomarked Red Knots for which the time budgets during DLW measurements were known, indicated that foraging away from the nest on open tundra is almost twice as costly as incubating a four-egg clutch. 4. During the incubation phase in the High Arctic, tundra-breeding shorebirds appear to incur among the highest DEE levels of any time of the year. The rates of energy expenditure measured here are among the highest reported in the literature so far, reaching inferred ceilings of sustainable energy turnover rates.

Complex Line Bundles over Simplicial Complexes and their Applications

Discrete vector bundles are important in Physics and recently found remarkable applications in Computer Graphics. This article approaches discrete bundles from the viewpoint of Discrete Differential Geometry, including a complete classification of discrete vector bundles over finite simplicial complexes. In particular, we obtain a discrete analogue of a theorem of Andr\'e Weil on the classification of hermitian line bundles. Moreover, we associate to each discrete hermitian line bundle with curvature a unique piecewise-smooth hermitian line bundle of piecewise constant curvature. This is then used to define a discrete Dirichlet energy which generalizes the well-known cotangent Laplace operator to discrete hermitian line bundles over Euclidean simplicial manifolds of arbitrary dimension

Atomistic Theory of Coherent Spin Transfer between Molecularly Bridged Quantum Dots

Time-resolved Faradary rotation experiments have demonstrated coherent transfer of electron spin between CdSe colloidal quantum dots coupled by conjugated molecules. We employ here a Green's function approach, using semi-empirical tight-binding to treat the nanocrystal Hamiltonian and Extended Huckel theory to treat the linking molecule Hamiltonian, to obtain the coherent transfer probabilities from atomistic calculations, without the introduction of any new parameters. Calculations on 1,4-dithiolbenzene and 1,4-dithiolcyclohexane linked nanocrystals agree qualitatively with experiment and provide support for a previous transfer Hamiltonian model. We find a striking dependence on the transfer probabilities as a function of nanocrystal surface site attachment and linking molecule conformation. Additionally, we predict quantum interference effects in the coherent transfer probabilities for 2,7-dithiolnaphthalene and 2,6-dithiolnaphthalene linking molecules. We suggest possible experiments based on these results that would test the coherent, through-molecule transfer mechanism.Comment: 12 pages, 9 figures. Submitted Phys. Rev.

Twelve Reasons Why I Stand Identified With The People Known As Disciples Of Christ

https://digitalcommons.acu.edu/crs_books/1320/thumbnail.jp

Drying and cracking mechanisms in a starch slurry

Starch-water slurries are commonly used to study fracture dynamics. Drying starch-cakes benefit from being simple, economical, and reproducible systems, and have been used to model desiccation fracture in soils, thin film fracture in paint, and columnar joints in lava. In this paper, the physical properties of starch-water mixtures are studied, and used to interpret and develop a multiphase transport model of drying. Starch-cakes are observed to have a nonlinear elastic modulus, and a desiccation strain that is comparable to that generated by their maximum achievable capillary pressure. It is shown that a large material porosity is divided between pore spaces between starch grains, and pores within starch grains. This division of pore space leads to two distinct drying regimes, controlled by liquid and vapor transport of water, respectively. The relatively unique ability for drying starch to generate columnar fracture patterns is shown to be linked to the unusually strong separation of these two transport mechanisms.Comment: 9 pages, 8 figures [revised in response to reviewer comments

Drying and cracking mechanisms in a starch slurry

Starch-water slurries are commonly used to study fracture dynamics. Drying starch-cakes benefit from being simple, economical, and reproducible systems, and have been used to model desiccation fracture in soils, thin film fracture in paint, and columnar joints in lava. In this paper, the physical properties of starch-water mixtures are studied, and used to interpret and develop a multiphase transport model of drying. Starch-cakes are observed to have a nonlinear elastic modulus, and a desiccation strain that is comparable to that generated by their maximum achievable capillary pressure. It is shown that a large material porosity is divided between pore spaces between starch grains, and pores within starch grains. This division of pore space leads to two distinct drying regimes, controlled by liquid and vapor transport of water, respectively. The relatively unique ability for drying starch to generate columnar fracture patterns is shown to be linked to the unusually strong separation of these two transport mechanisms.Comment: 9 pages, 8 figures [revised in response to reviewer comments

Characterization of Recombinant Human PRG4 as an Ocular Surface Boundary Lubricant

Introduction: Dry-eye disease involves tear film instability that can result in surface-to-surface contact between the cornea and eyelid or contact lens, where boundary lubrication can be dominant1. Motivated by the recent discovery that proteoglycan 4 (PRG4, a mucin-like glycoprotein originally discovered in synovial fluid as a boundary lubricant2), functions as an ocular surface boundary lubricant3, advances in recombinant protein expression technology4, and PRG4’s potential use as a friction-reducing contact lens coating, the objectives of this study were to: 1) biochemically characterize recombinant human PRG4 (rh- PRG4); and 2) assess the boundary lubricating properties of rh-PRG4, both before and after autoclave sterilization, at a cornea-contact lens material (PDMS) biointerface. Methods: SDS-PAGE western blot analysis using a variety of anti-PRG4 antibodies and lectins was performed on native PRG4 (nPRG4) and rh-PRG4 samples, both nonreduced and reduced, with and without enzymatic removal of O-linked glycosylations. Human corneas and PDMS were articulated against each other, subject to physiological loads of 8-25 kPa, at effective sliding velocities of 0.3-30 mm/s. Test lubricant sequences were A) saline, rh-PRG4 @300μg/mL, nPRG4 @300μg/mL, and saline; and B) saline, autoclaved rh-PRG4 @300μg/mL, rh-PRG4 @300μg/mL, and saline. Static and kinetic coefficients of friction were calculated. Results: rh-PRG4 demonstrated similar immunoreactivity to nPRG4, and effectively lowered friction at the cornea-PDMS biointerface. Western blotting indicated immunoreactive rh-PRG4 bands had a similar apparent molecular weight (MW) to nPRG4, and decreased appropriately upon reduction as well as enzymatic removal of glycosylations. Kinetic friction coefficients, which were highest in saline (0.31±0.06 to 0.40±0.06, mean±SEM), were similar in rh-PRG4 (0.12±0.01 to 0.25±0.03) and nPRG4 (0.19±0.02 to 0.28±0.03) across all velocities. Autoclaved rh-PRG4 had similar values to rh-PRG4 as well (0.19±0.02 to 0.26±0.04, 0.16±0.02 to 0.26±0.02, respectively). Conclusions: rh-PRG4 demonstrates similar biochemical and ocular surface lubricating properties to nPRG4, and may function as an effective friction-reducing contact lens coating

Large area silicon sheet by EFG

Progress in a program to produce high speed, thin, wide silicon sheets for fabricating 10% efficient solar cells is reported. An EFG ribbon growth system was used to perform growth rate and ribbon thickness experiments. A new, wide ribbon growth system was developed. A theoretical study of stresses in ribbons was also conducted. The EFG ribbons were observed to exhibit a characteristic defect structure which is orientation dependent in the early stages of growth

An Application of Feynman-Kleinert Approximants to the Massive Schwinger Model on a Lattice

A trial application of the method of Feynman-Kleinert approximants is made to perturbation series arising in connection with the lattice Schwinger model. In extrapolating the lattice strong-coupling series to the weak-coupling continuum limit, the approximants do not converge well. In interpolating between the continuum perturbation series at large fermion mass and small fermion mass, however, the approximants do give good results. In the course of the calculations, we picked up and rectified an error in an earlier derivation of the continuum series coefficients.Comment: 16 pages, 4 figures, 5 table

Response of angina and ischemia to long-term treatment in patients with chronic stable angina: A double-blind randomised individualized dosing trial of nifedipine, propranolol and their combination

AbstractSeventy-four patients with chronic stable mild angina, mild coronary artery disease (83% had one- or two-vessel disease) and normal left ventricular function were studied to measure the response of treadmill exercise performance and painful and silent ischemia in the ambulatory setting to randomly assigned treatment with nifedipine or propranolol and their combination; titration to maximal tolerated dosages was performed in doubleblind manner.At 3 months both nifedipine and propranolol reduced the weekly angina rate (p < 0.05); during treadmill exercise testing, increases (p < 0.05) were noted in time to angina and total exercise time and decreases in maximal ST depression at the end of exercise. There were no differences between the responses to nifedipine and propranolol and no significant additional changes were seen after another 3 months of therapy. The combination of nifedipine and propranolol reduced the number of patients with angina on exercise treadmill testing from 64% to 38% (p < 0.05).During ambulatory electrocardiographic monitoring before treatment, there were 1.4 ± 2.4 (mean ± SD) episodes/24 h of painful ischemia and a very low silent ischemia frequency: mean 1.1 ± 2.7 episodes/24 h, mean duration 16 ± 25 min/24 h. Treatment with propranolol and nifedipine resulted in reduction of episodes and duration of painful and painless ischemia; approximately 77% of patients were free of all ischemic episodes.It is concluded that patients with chronic stable mild angina have a low incidence of silent ischemia. Nifedipine or propranolol alone, titrated to individualized maximally tolerated dosages, are equally effective in long-term control of painful and painless ischemia, anginal episodes and exercise-induced ischemia. Combination therapy further reduced only exercise-induced angina and maximal exercise-induced ST depression