Results 61 to 70 of about 4,557,251 (286)

A New Theorem on The Existence of Positive Solutions of Singular Initial-Value Problem for Second Order Differential Equations

Communications in Advanced Mathematical Sciences, 2019
We proved a new theorem on the existence of positive solutions to initial-value problems for second-order nonlinear singular differential equations. The existence of solutions is proven under considerably weaker than previously known conditions.
Afgan Aslanov
doaj   +1 more source

The Existence of Einstein Static Universes and their Stability in Fourth order Theories of Gravity

, 2008
We investigate whether or not an Einstein Static universe is a solution to the cosmological equations in $f(R)$ gravity. It is found that only one class of $f(R)$ theories admits an Einstein Static model, and that this class is neutrally stable with ...
A. S. Eddington, B. de Witt, G. F. R. Ellis, I. Chavel, Naureen Goheer, Peter K S Dunsby, Rituparno Goswami   +6 more
core   +1 more source

Revealing the structure of land plant photosystem II: the journey from negative‐stain EM to cryo‐EM

FEBS Letters, EarlyView.
Advances in cryo‐EM have revealed the detailed structure of Photosystem II, a key protein complex driving photosynthesis. This review traces the journey from early low‐resolution images to high‐resolution models, highlighting how these discoveries deepen our understanding of light harvesting and energy conversion in plants.
Roman Kouřil
wiley   +1 more source

A note on the existence of positive solutions of singular initial-value problem for second order differential equations

Electronic Journal of Qualitative Theory of Differential Equations, 2015
We are interested in the existence of positive solutions to initial-value problems for second-order nonlinear singular differential equations. Existence of solutions is proven under conditions which are directly applicable and considerably weaker than ...
Afgan Aslanov
doaj   +1 more source

Non-existence of periodic solutions in fractional-order dynamical systems and a remarkable difference between integer and fractional-order derivatives of periodic functions

, 2011
Using the Mellin transform approach, it is shown that, in contrast with integer-order derivatives, the fractional-order derivative of a periodic function cannot be a function with the same period.
Kaslik, Eva, Sivasundaram, Seenith
core   +1 more source

Model Existence for Higher Order Logic

, 1997
In this paper we provide a semantical meta-theory that will support the development of higher-order calculi for automated theorem proving like the corresponding methodology has in first-order logic. To reach this goal, we establish classes of models that adequately characterize the existing theorem-proving calculi and we present a standard methodology ...
Benzmüller, Christoph, Kohlhase, Michael   +1 more
openaire   +3 more sources

Existence, Uniqueness and Structure of Second Order Absolute Minimisers [PDF]

Archive for Rational Mechanics and Analysis, 2018
Let $ \subseteq \mathbb{R}^n$ be a bounded open $C^{1,1}$ set. In this paper we prove the existence of a unique second order absolute minimiser $u_\infty$ of the functional \[ \mathrm{E}_\infty (u,\mathcal{O})\, :=\, \| \mathrm{F}(\cdot, u) \|_{L^\infty( \mathcal{O} )}, \ \ \ \mathcal{O} \subseteq \text{ measurable}, \] with prescribed boundary ...
Nikos Katzourakis, Roger Moser
openaire   +3 more sources

Mapping the evolution of mitochondrial complex I through structural variation

FEBS Letters, EarlyView.
Respiratory complex I (CI) is crucial for bioenergetic metabolism in many prokaryotes and eukaryotes. It is composed of a conserved set of core subunits and additional accessory subunits that vary depending on the organism. Here, we categorize CI subunits from available structures to map the evolution of CI across eukaryotes. Respiratory complex I (CI)
Dong‐Woo Shin, Tingting Chen, James A. Letts   +2 more
wiley   +1 more source

Existence and decay of solutions to a viscoelastic plate equation

Electronic Journal of Differential Equations, 2016
In this article we study the fourth-order viscoelastic plate equation $$ u_{tt} + \Delta^2 u -\int_0^t g(t-\tau)\Delta^2u(\tau)d\tau = 0 $$ in the bounded domain $\Omega=(0,\pi)\times(-\ell,\ell)\subset\mathbb{R}^2$ with non traditional boundary ...
Salim A. Messaoudi, Soh Edwin Mukiawa
doaj  

Existence of solutions for fourth-order nonlinear boundary value problems

Advances in Difference Equations, 2021
In this paper, we discuss the existence and approximation of solutions for a fourth-order nonlinear boundary value problem by using a quasilinearization technique. In the presence of a lower solution α and an upper solution β in the reverse order α ≥ β $\
Mingzhu Huang
doaj   +1 more source