Bursting neurons with coupling delays

A pair of Hindmarsh–Rose neurons with delayed coupling is studied. Bifurcations due to time-lag and coupling and stability of the stationary state that corresponds to the quiescence behavior are analyzed. Bursting is created by coupling and its properties strongly depend on the time-lag. In particular, there is a domain of values of time-lags which renders the bursting of the two neurons exactly synchronous.     

Electrons in thin films

The method of evaluation of broken-symmetry Green’s function is presented. This method was applied to electron subsystem of a thin film. It was found that electron concentrations are spatially dependent and their spatial distribution proves the existence of skin effect. The skin effect is most expressed in the films of minimal thickness. The internal energy of electrons lying in the film Fermi volume, decreases with the increase of temperature. It is the consequence of the Pauli principle, which does not allow change of electron velocities. Introduced heat increases electron effective masses and this leads to the decrease of internal energy.     

Shape‐Memory PVDF Exhibiting Switchable Piezoelectricity

In this study, a material is designed which combines the properties of shape‐memory and electroactive polymers. This is achieved by covalent cross‐linking of polyvinylidene fluoride. The resulting polymer network exhibits excellent shape‐memory properties with a storable strain of 200%, and fixity as well as recovery values of 100%. Programming upon rolling induces the transformation from the nonelectroactive α‐phase to the piezoelectric β‐phase. The highest β‐phase content is found to be 83% for a programming strain of 200% affording a d₃₃ value of −30 pm V⁻¹. This is in good accordance with literature known values for piezoelectric properties. Thermal triggering this material does not only result in a shape change but also renders the material nonelectroactive.

     

Das Gleichgewicht in binären Systemen,die als eine Komponente Kresole enthalten

Zusammenfassung Die Zustandsdiagramme von acht binären Systemen, die einerseits auso-, m- undp- Kresol, anderseits aus - und -Naphthylamin und Diphenylamin zusammengesetzt sind, wurden nach der Methode der thermischen Analyse untersucht. Die Versuche zeigen, da\ das Diphenylamin mit deno- undp-Kresolen nur mechanische Mischungen gibt, und da\ beide Naphthylamine mit allen isomeren Kresolen Monokresolate von der Zusammensetzung: eine Molekel Amin — eine Molekel Kresol bilden.     

Note on a conjecture about Bernstein type inequalities for multivariate polynomials

There are fine extensions of the univariate Bernstein-Szeg? inequality for multivariate polynomials considered on a convex domain K. The current one estimates the gradient of the polynomial P at a point x ∈ K by constant times degree, ‖P‖ _C(K) and a geometrical factor. The best constant is within [2, 2√2]. In this note we disprove the conjecture (based on some particular cases) that the best constant is 2.     

Sopra gli sviluppi asintotici e la trasformazione di Laplace

Sunto. SiaF(x) una funzione definita perx>0, integrabiel e indichiamo conf(s) la sua trasformata diLaplace. In questa Nota l'A. dà alcuni risultati per lo sviluppo asintotico della funzioneF(x), se la funzionef(s) possiede uno sviluppo asintotico.