Periodic solutions of quasilinear non-autonomous systems with impulses

The paper considers a system of differential equations with impulse perturbations at fixed moments in time of the form where x ? R ⁿ, ε is a small parameter, Sufficient conditions have been found for existence of the periodic solution of the given system in the critical and non-critical cases.     

Spectral and scattering theory for a Schrödinger operator with a class of momentum-dependent long-range potentials

Let be the selfadjoint operator for the static electromagnetic field where W _j for 0, 1, 2, ..., n is a sum of (i) a short-range potential and (ii) a smooth long-range potential decreasing at as |x|^- with in (0, 1]. Then for >1/2, asymptotic completeness holds for the scattering system (H, H ₀).     

Formation of collisionless high-beta plasmas by odd-parity rotating magnetic fields

Odd-parity rotating magnetic fields (RMFo) applied to mirror-configuration plasmas have produced average electron energies exceeding 200 eV at line-averaged electron densities of approximately 10(12) cm-3. These plasmas, sustained for over 10(3)tauAlfven, have low Coulomb collisionality, vc* triple bond L/lambdaC approximately 10(-3), where lambdaC is the Coulomb scattering mean free path and L is the plasma's characteristic half length. Divertors allow reduction of the electron-neutral collision frequency to values where the RMFo coupling indicates full penetration of the RMFo to the major axis.     

On minimal nonlinearities which permit bifurcation from the continuous spectrum

Bifurcation from the continuous spectrum of a linearized operator is of interest in many physical problems. For example it occurs in the nonlinear Klein-Gordon equation and in nonlinear integrodifferential equations as the Choquard problem; it further appears in nonlinear integral equations of the convolution type. A general theory enclosing all these problems is not yet known. To understand the basic phenomena, we therefore consider monotone differential operators whose linearisations have a purely continuous spectrum. It is shown that in fact the lowest point of the continuous spectrum is a bifurcation point, if the nonlinearity grows sufficiently strong.     

Field ionization of strongly magnetized rydberg positronium: A new physical mechanism for positron accumulation

Magnetized Rydberg positronium forms when an energetic positron ( e(+)) slows within a tungsten crystal and picks up an electron ( e(-)) as it emerges in a strong magnetic field. The signature is equal numbers of e(+) and e(-) when a weak electric field is applied, either of which can be accumulated and counted. The new e(+) accumulation technique is simple, robust, and much more efficient than any other demonstrated to be compatible with a cryogenic vacuum. Possible applications include the study of cold single component plasmas of e(+) and the formation of cold antihydrogen.     

Quantitative determination of N-[trans-2-(dimethylamino)-cyclopentyl]-N-(3',4'-dichlorophenyl)propan amide, its 2H5-labeled analogue and their N-dealkylated metabolites in dog serum by capillary gas chromatography-mass spectrometry

This paper describes the development of a capillary gas chromatographic--mass spectrometric method for the determination of N-[trans-2-(dimethylamino)cyclopentyl]-N-(3',4'-dichlorophenyl)propan amide and its metabolites in serum. The method utilizes an automated sample preparation whereby drug, metabolites and internal standard are extracted from polar serum components by adsorption chromatography onto an XAD-type resin. The N-demethylated metabolites are derivatized by acetylation prior to chromatography. Detection is by mass spectrometry with chemical ionization. This method was utilized to determine levels of unlabeled and pentadeuterated drug and their respective metabolites in canine serum after oral co-administration. No significant kinetic isotope effects were observed for either absorption or metabolism.     

Threshold phenomena for the first initial boundary value problem of the FitzHugh–Nagumo equations

Under biologically reasonable assumptions the threshold phenomena for the first initial boundary value problem of FitzHugh–Nagumo equations is proved.