880 research outputs found
King eider wing molt: inferences from stable isotope analyses
Thesis (M.S.) University of Alaska Fairbanks, 2004The western North American population of the king eider is thought to have declined by over 50% between 1974 and 1996 without an apparent cause. The non-breeding period of king eiders consists of 80-100% of their annual cycle if not impossible by observation. I used stable carbon and nitrogen isotope values of feathers and muscle to examine the wing molt and migration ecology of king eiders in 2003. Eider primary feathers were isotopically homogenous along the length of the feather, implying invariable diets during wing molt. Captive eiders in their hatch-year did not fractionate nitrogen isotopes, potentially indicating preferential protein allocation associated with growth. Six percent of female eiders sampled molted primary feathers on their breeding grounds, which had not been previously substantiated. Tissue samples from both genders corroborated dietary shifts inherent in switching from a marine to terrestrial diet. Carbon isotopes of feathers from satellite-transmittered males were correlated with longitude of their known wing molt locations indicating that the gradient of carbon isotopes can be used to draw inferences about molt location of eiders
Elastometry of deflated capsules elastic moduli from shape and wrinkle analysis
Elastic capsules, prepared from droplets or bubbles attached to a capillary (as in a pendant drop tensiometer), can be deflated by suction through the capillary. We study this deflation and show that a combined analysis of the shape and wrinkling characteristics enables us to determine the elastic properties in situ. Shape contours are analyzed and fitted using shape equations derived from nonlinear membrane-shell theory to give the elastic modulus, Poisson ratio and stress distribution of the membrane. We include wrinkles, which generically form upon deflation, within the shape analysis. Measuring the wavelength of wrinkles and using the calculated stress distribution gives the bending stiffness of the membrane. We illustrate this method on two very different capsule materials: polymerized octadecyltrichlorosilane (OTS) capsules and hydrophobin (HFBII) coated bubbles. Our results are in agreement with the available rheological data. For hydrophobin coated bubbles the method reveals an interesting nonlinear behavior consistent with the hydrophobin molecules having\ud
a rigid core surrounded by a softer shell
he Effects of Informal Social Structures: A Cognition–Structure–Action Approach
The purpose of this article is to examine the effects of epistemic motives and social structures on individual actions and the implications for organizational outcomes. It has been suggested that the informal social structures that develop within organizations affect the behavior of individuals, perhaps more so than formal structure. If this is true, when studying organizations it may be important to examine the effects of informal social structures on individual actions and organizational outcomes. Drawing on findings from epistemic motive theory and expanding social capital theory, a cognition–structure–action model is introduced as a way to begin systematically examining the informal structure of relations that form within organizations on individual behavior. A multilevel perspective is used to examine the interrelationships between formal organizational structures and epistemic motivation and the formation of informal social structure. This article contributes to network research by examining potential cognitive antecedents to network structure
The Identification of cis-II, I2-Methylene-2-hydroxyoctadecanoic Acid from \u3ci\u3eThiobacillus thiooxidans\u3c/i\u3e
A polar fatty acid has been observed as a component of an
ornithine-containing lipid of Thiobacillus thiooxidans. A
comparison of thin layer chromatographic mobilities of reference
compounds to those of the natural acid and its derivatives
suggested that the acid was a 2-hydroxy fatty acid.
The presence of a cyclopropane function in the acid was
indicated by l4e-Iabeling experiments and infrared spectroscopy.
Mass spectrometry of the methyl ester and the acetylated
methyl ester of the natural acid provided a molecular
weight for the acid. Equivalent chain lengths were determined
for the natural acid, the acid obtained by oxidative
decarboxylation of the natural acid with permanganate, and
the acids derived through reductive ring cleavage of the
cyclopropane group in the ester of the oxidatively decarboxylated
natural acid. The mass spectral data, the equivalent
chain length determinations, and the permanganate oxidation
study clearly indicated that the acid possessed an 18-
carbon chain with a methylene bridge and a 2-hydroxyl
function. The equivalent chain length determinations
further suggested that the cyclopropane group had the cis
configuration. Mass spectrographic analysis of the branched
chain esters obtained by reductive cleavage of the ester
which was in turn derived through oxidative decarboxylation
of the natural acid allowed the assignment of the 11,12
position for the cyclopropane group. Based on these data,
the polar acid is proposed to be cis-ll, 12-methylene-2-
hydroxyoctadecanoic acid
Surface moisture increases microcracking and water vapour permeance of apple fruit skin
Surface moisture induces microcracking in the cuticle of fruit skins. Our objective was to study the effects of surface moisture on cuticular microcracking, the permeance to water vapour and russeting in developing ‘Pinova’ apple fruit. Surface moisture was applied by fixing to the fruit a plastic tube containing deionized water. Microcracking was quantified by fluorescence microscopy and image analysis following infiltration with acridine orange. Water vapour permeance was determined gravimetrically using skin segments (ES) mounted in diffusion cells. Cumulative water loss through the ES increased linearly with time. Throughout development, surface moisture significantly increased skin permeance. The effect was largest during early development and decreased towards maturity. Recovery time courses revealed that following moisture treatment of young fruit for 12 days, skin permeance continued to increase until about 14 days after terminating the moisture treatment. Thereafter, skin permeance decreased over the next 28 days, then approaching the control level. This behaviour indicates gradual healing of the impaired cuticular barrier. Nevertheless, permeance still remained significantly higher compared with the untreated control. Similar patterns of permeance change were observed following moisture treatments at later stages of development. The early moisture treatment beginning at 23 DAFB resulted in russeting of the exposed surfaces. There was no russet in control fruit without a tube or in control fruit with a tube mounted for 12 days without water. The data demonstrate that surface moisture increases microcracking and water vapour permeance. This may lead to the formation of a periderm and, hence, a russeted fruit surface
Broadband interactive services provided through TV-centric technologies via bidirectional satellite connection
Stationary shapes of deformable particles moving at low Reynolds numbers
Lecture Notes of the Summer School ``Microswimmers -- From Single Particle
Motion to Collective Behaviour'', organised by the DFG Priority Programme SPP
1726 (Forschungszentrum J{\"{u}}lich, 2015).Comment: Pages C7.1-16 of G. Gompper et al. (ed.), Microswimmers - From Single
Particle Motion to Collective Behaviour, Lecture Notes of the DFG SPP 1726
Summer School 2015, Forschungszentrum J\"ulich GmbH, Schriften des
Forschungszentrums J\"ulich, Reihe Key Technologies, Vol 110, ISBN
978-3-95806-083-
Voices in the field: A mobile phone based application to improve marginal farmers livelihoods
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