Search results for "neuma"
showing 10 items of 154 documents
Modular Structures on Trace Class Operators and Applications to Landau Levels
2009
The energy levels, generally known as the Landau levels, which characterize the motion of an electron in a constant magnetic field, are those of the one-dimensional harmonic oscillator, with each level being infinitely degenerate. We show in this paper how the associated von Neumann algebra of observables displays a modular structure in the sense of the Tomita–Takesaki theory, with the algebra and its commutant referring to the two orientations of the magnetic field. A Kubo–Martin–Schwinger state can be built which, in fact, is the Gibbs state for an ensemble of harmonic oscillators. Mathematically, the modular structure is shown to arise as the natural modular structure associated with the…
Nonlinear Nonhomogeneous Elliptic Problems
2019
We consider nonlinear elliptic equations driven by a nonhomogeneous differential operator plus an indefinite potential. The boundary condition is either Dirichlet or Robin (including as a special case the Neumann problem). First we present the corresponding regularity theory (up to the boundary). Then we develop the nonlinear maximum principle and present some important nonlinear strong comparison principles. Subsequently we see how these results together with variational methods, truncation and perturbation techniques, and Morse theory (critical groups) can be used to analyze different classes of elliptic equations. Special attention is given to (p, 2)-equations (these are equations driven…
The phylogenetic position and taxonomic status of Sterechinus bernasconiae Larrain, 1975 (Echinodermata, Echinoidea), an enigmatic Chilean sea urchin
2015
15 pages; International audience; Sterechinus is a very common echinoid genus in benthic communities of the Southern Ocean. It is widely distributed across the Antarctic and South Atlantic Oceans and has been the most frequently collected and intensively studied Antarctic echinoid. Despite the abundant literature devoted to Sterechinus, few studies have questioned the systematics of the genus. Sterechinus bernasconiae is the only species of Sterechinus reported from the Pacific Ocean and is only known from the few specimens of the original material. Based on new material collected during the oceanographic cruise INSPIRE on board the R/V Melville, the taxonomy and phylogenetic position of th…
Enseñanza de las ciencias : revista de investigación y experiencias didácticas
2020
Nuestro objetivo en esta investigación es identificar las dificultades de aprendizaje que tienen los niños de 1.º a 3.º grado de educación primaria en la construcción de los números naturales. Tales dificultades no proceden de la enseñanza, sino de las propias matemáticas y para poder observar esas dificultades, es necesario reducir el problema a los elementos primitivos. Con los modelos teóricos locales como marco teórico y metodológico, se ha diseñado un modelo de enseñanza traduciendo el componente formal (modelo de J. Von Neumann) a una secuencia de actividades con el uso de material manipulativo. Se analiza la experiencia de enseñanza y en los resultados se destacan y explican las difi…
Three solutions for a Neumann boundary value problem involving the p-Laplacian
2005
In this note we prove the existence of an open interval ]λ', λ"[ for each λ of which a Neumann boundary value problem involving the p-Laplacian and depending on λ admits at least three solutions. The result is based on a recent three critical points theorem.
Evaluation of different mechanical fruit harvesting systems and oil quality in very large size olive trees
2014
In 2006 and 2009, trials were carried out in the Apulia region in Southern Italy to evalu-ate the possibility of mechanizing olive harvesting in groves of old and very large trees. The trees belonged to the cultivars ‘Cellina di Nardò’ and ‘Ogliarola Salentina’. They were 60-100 years old and 7-9 m tall with a canopy volume of 140-360 m3. In the first half of November 2006, with a mechanical beater mounted on a tractor plus hand-held pneumatic combs, the harvesting yield was close to 90% of the total olives present in the canopy, and the harvesting working productivity was around 60 kg of harvested olives h-1 worker-1. With a self-propelled shaker attached to the main branches the harvestin…
Singular Neumann (p, q)-equations
2019
We consider a nonlinear parametric Neumann problem driven by the sum of a p-Laplacian and of a q-Laplacian and exhibiting in the reaction the competing effects of a singular term and of a resonant term. Using variational methods together with suitable truncation and comparison techniques, we show that for small values of the parameter the problem has at least two positive smooth solutions.
Resonant neumann equations with indefinite linear part
2015
We consider aseminonlinear Neumann problem driven by the $p$-Laplacian plus an indefinite and unbounded potential. The reaction of the problem is resonant at $\pm \infty$ with respect to the higher parts of the spectrum. Using critical point theory, truncation and perturbation techniques, Morse theory and the reduction method, we prove two multiplicity theorems. One produces three nontrivial smooth solutions and the second four nontrivial smooth solutions.
Solutions to the 1-harmonic flow with values into a hyper-octant of the N-sphere
2013
Abstract We announce existence results for the 1-harmonic flow from a domain of R m into the first hyper-octant of the N -dimensional unit sphere, under homogeneous Neumann boundary conditions. The arguments rely on a notion of “geodesic representative” of a BV-vector field on its jump set.
THE 1-HARMONIC FLOW WITH VALUES IN A HYPEROCTANT OF THE N-SPHERE
2014
We prove the existence of solutions to the 1-harmonic flow — that is, the formal gradient flow of the total variation of a vector field with respect to the [math] -distance — from a domain of [math] into a hyperoctant of the [math] -dimensional unit sphere, [math] , under homogeneous Neumann boundary conditions. In particular, we characterize the lower-order term appearing in the Euler–Lagrange formulation in terms of the “geodesic representative” of a BV-director field on its jump set. Such characterization relies on a lower semicontinuity argument which leads to a nontrivial and nonconvex minimization problem: to find a shortest path between two points on [math] with respect to a metric w…