Results 131 to 140 of about 488,781 (331)

Why we age

open access: yesBiological Reviews, EarlyView.
ABSTRACT Three categories of explanations exist for why we age: mechanistic theories, which omit reference to evolutionary forces; weakening force of selection theories, which posit that barriers exist that prevent evolutionary forces from optimising fitness in ageing; and optimisation theories, which posit that evolutionary forces actually select for ...
Michael S. Ringel
wiley   +1 more source

Gluing approximate solutions of minimum type on the Nehari manifold

open access: yesElectronic Journal of Differential Equations, 2001
In the last decade or so, variational gluing methods have been widely used to construct homoclinic and heteroclinic type solutions of nonlinear elliptic equations and Hamiltonian systems.
Yanyan Li, Zhi-Qiang Wang
doaj  

The Mountain Passes in Norðradalur

open access: yesFróðskaparrit - Faroese Scientific Journal, 2017
The article deals with the names of two mountain passes used by people travelling to or from Norðradalur. The passes exhibit a wide variety of names in written and oral sources. The more northerly one is called Norðaraskarð, Norðaraskarð í Norðradali, Norð­ara Norðradalsskarð, Neytaskarð, Norðradals­ skarð, Skarðið, while its neighbour to the south ...
openaire   +2 more sources

A review of the historic and present ecological role of aquatic and shoreline wood, from forest to deep sea

open access: yesBiological Reviews, EarlyView.
ABSTRACT The ecology of forests, their losses, and terrestrial wood decomposition dynamics have been intensively studied and reviewed. In the aquatic realm, reviews have concentrated on large wood (LW) in rivers and the transition from freshwater to marine environments in the Pacific Northwest of North America. However, a comprehensive global synthesis
Jon Dickson   +9 more
wiley   +1 more source

Mountain Pass on a Closed Convex Set

open access: yesJournal of Mathematical Analysis and Applications, 1997
The author proves a version of the mountain pass theorem for a functional defined on a closed convex set of a Banach space. Such a functional does not necessarily satisfy the Palais-Smale condition. This abstract result is applied to the study of the semilinear Dirichlet problem \[ \begin{cases} -\Delta u+u^2 =f(x) \quad & \text{in } \Omega,\\ u=0 ...
openaire   +2 more sources

Beyond mammals: the evolution of chewing and other forms of oropharyngeal food processing in vertebrates

open access: yesBiological Reviews, EarlyView.
ABSTRACT Oropharyngeal food processing exhibits a remarkable diversity among vertebrates, reflecting the evolution of specialised ‘processing centres’ associated with the mandibular, hyoid, and branchial arches. Although studies have detailed various food‐processing strategies and mechanisms across vertebrates, a coherent and comprehensive terminology ...
Daniel Schwarz   +6 more
wiley   +1 more source

LargeH-surfaces via the mountain-pass-lemma

open access: yesMathematische Annalen, 1985
L'A. considère le système \(\Delta u=2Hu_ x\wedge u_ y\) où \(B=disque\) unité de \({\mathbb{R}}^ 2\) avec condition de Dirichlet ou condition de Plateau. L'énergie associée à ce système est \(E(u)=(1/2)\int | \nabla u|^ 2+(2H/3)\int u\circ u_ x\bigwedge u_ x\). L'A. montre que si E admet un minimum local \b{u}, alors il existe une deuxième solution \(\
openaire   +1 more source

Early evolutionary history of the seed

open access: yesBiological Reviews, EarlyView.
ABSTRACT The seed is an essential stage in the life history of gymnospermous and angiospermous plants, facilitating both their survival and dispersal. We reappraise knowledge of the evolutionary history of the gymnospermous seed, from its origin in the late Devonian through to the well‐known end‐Permian extinctions – an interval encompassing the ...
Richard M. Bateman   +2 more
wiley   +1 more source

Existence of solitons for discrete nonlinear Schrodinger equations

open access: yesElectronic Journal of Differential Equations, 2016
By using the Mountain Pass Lemma, we establish sufficient conditions for the existence of solitons for the discrete nonlinear Schrodinger equations.
Haiping Shi, Yuanbiao Zhang
doaj  

Home - About - Disclaimer - Privacy