Studies on the exchange of gramicidin in liposomes

The exchange of gramicidin between liposomes made of two different kinds of phospholipids has been studied using a fluorescent probe (pyranine). The experimentally observed rate of exchange is compared with that of nigericin, which is a simple carrier. Possible reasons for the difference in the rate of exchange are discussed and probable mechanisms suggested. It is proposed that gramicidin exchanges between vesicles by a contact mechanism.     

Electron Energy Distribution Functions in CO2 Laser Mixture: The Effects of Second Kind Collisions from Metastable Electronic States

Electron energy distribution functions (eedf) in CO₂ laser discharge (He—CO₂—N₂—CO mixture) have been calculated by solving the Boltzmann equation in the presence of given concentrations of excited (vibrational and electronic) states. The results show a well structured eedf as a result of second kind collisions coming from metastable electronic states of N₂ and He as well as a strong dependence of rate coefficients for CO₂ dissociation and for the ionization of the different species.     

The experimental structure of199Au and the interacting boson-fermion model

Gamma rays of¹⁹⁹Au obtained after double neutron capture in¹⁹⁷Au were measured at the ILL high flux reactor. A level scheme up to 1770 keV excitation energy is established. The result is compared with IBFM and Boson-Fermion-Symmetry calculations.     

Parity violation at neutron p-wave resonances of238U and232Th and related questions

Parity violation effects have been studied at 40 neutron p-wave resonances of the even-even nuclei²³⁸U and²³²Th. Of these 11 show parity violation effects larger than 2 standard deviations, making parity violation a rather common phenomenon. Parity mixing up to 10% has been found. The root-mean squared matrix elements for parity violation derived from these resonances are M=0.58 (+0.50/-0.25) meV for²³⁸U, respectively 1.39 (+0.35/-0.38) meV for²³²Th.     

Correlation between gravitational-wave detectors and particle detectors during SN1987A

Summary A review of the correlations between gravitational-wave detectors and particle detectors during SN1987A is given. The correlation between the Maryland and Rome g.w. detectors with the Mont Blanc neutrino detector is illustrated. This correlation extends during a period of one or two hours centred at 2∶45 UT of 23 February 1987, with the ?neutrino? signals delayed by (1.1±0.5) s and with a probability of the order of 10⁻⁵ to be accidental. Using the data obtained with the Kamiokande and IMB detectors, with the same statistical choices and procedures for the data analysis used previously, the above result is confirmed with a probability of the order of 10⁻³ or 10⁻⁴ that the additional correlation be accidental. Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990.     

A family of centered forms for a polynomial

The general centered form for multi-variate polynomials is investigated and a computing procedure is proposed that results in a certain superset. Based on this procedure the optimal centered forms for monomials and for some special cases of polynomials are investigated.     

Nodal surfaces of Fourier series: Fundamental invariants of structured matter

Periodic Nodal Surfaces (PNS) of Fourier series are derived and classified as fundamental invariants of structured matter. Relationships to periodic minimal surfaces PMS and to periodic zero potential surfaces (POPS) are given. A basic set of cubic PNS is represented in arithmetic form. The special importance of the invariance of the zeros to the type of the potential is stressed.     

A note on the solution of a class of two-point boundary value problems involving a mixed boundary condition

In this note, we consider a class of two-point boundary value problems involving a pa- rameter in one of the boundary conditions. We shall show that if we know the solution corresponding to a particular value of the parameter, then the solution for any other value of the parameter can be obtained by a simple algebraic method.     

Growth of InP/InGaAs multiple quantum well structures by chemical beam epitaxy

InP/InGaAs multiple quantum well structures with up to 200 periods have been grown by CBE. These structures exhibit exceptional lateral uniformity, measured as ±1 Å in period, ±13 ppm in lattice mismatch and ±0.5 nm in wavelength across a 2 inch wafer. Good surface morphology, sharp interfaces and excellent growth control have all been demonstrated.