Results 181 to 190 of about 2,055,605 (307)

Coexisting ant species differ in ability to meet their intrinsic nutritional needs

open access: yesOikos, EarlyView.
Coexisting species are often assumed to reduce competition by foraging for foods that differ in nutrient composition, but few studies test whether field nutritional differences correspond to intrinsic differences in macronutrient selectivity. We compared field estimates of worker trophic position (tissue isotopes: δ15N) and worker tissue stoichiometry (
Hannah L. Riskas   +4 more
wiley   +1 more source

An algebraic model of transitive differential geometry [PDF]

open access: yesBulletin of the American Mathematical Society, 1964
Guillemin, Victor W., Sternberg, Shlomo
openaire   +2 more sources

Impact of Packaging and Recycling Systems on Material Recirculation: A Stage‐Decomposition Model

open access: yesPackaging Technology and Science, EarlyView.
A system‐level view emerges from decomposing recycling into four stages (participation, collection, sorting and process yield), diagnosing constraints and targeting interventions. Cumulative equivalent uses (CEUs) quantify long‐term retention, revealing marginal improvements at high baselines generate disproportionately larger gains than low‐baseline ...
Diogo Figueirinhas   +3 more
wiley   +1 more source

New views of some invariants associated with the Cartesian 2D velocity gradient tensor

open access: yesQuarterly Journal of the Royal Meteorological Society, EarlyView.
Vorticity and divergence of horizontal flow are fundamental quantities in meteorology; both are linear functions of the four elements of the 2D velocity gradient tensor and both are formally unchanged under coordinate rotation. We explore four quadratic functions of the elements that are geometrically invariant in this sense, finding some novel ...
I. Roulstone, S. A. Clough, A. A. White
wiley   +1 more source

Sliding Mode Control in Aerospace Applications: A Survey

open access: yesInternational Journal of Robust and Nonlinear Control, EarlyView.
ABSTRACT Sliding mode control (SMC) enjoys robustness to matched and unmatched (in the case of minimum phase input‐output dynamics) bounded perturbations, and finite time convergence. Second‐order and higher‐order sliding mode control systems (2‐SMC/HOSMC) retain all the advantages of sliding mode control, but in addition can be applied to systems of ...
Yuri Shtessel, Christopher Edwards
wiley   +1 more source

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