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The mutual influence of 21 factors pertaining to terrain, weather, forest and snowpack have been discussed by 10 experts. The semantic (nil, weak, medium, high) evaluations are translated as membership degrees of fuzzy sets, and averaged between the experts by taking their fuzzy expectation value, yielding a 21 × 21 fuzzy matrix for direct interactions. Fuzzy successive multiplications and additions of the matrix give the indirect interactions. The activity and the passivity of the factors with respect to avalanches is represented by directed weighted graphs, and the average semantic values by a 4 × 4 matrix: the activity (passivity) is weak (strong) for tree damage; medium (nil) for altitude; medium (weak) for ground shape; medium (medium) for vegetation, soil, wind, microclimate, tree type, vertical distribution and mechanics of trees, snowpack distribution and snow gliding; strong (nil) for ground inclination and exposition, weather; strong (medium) for heat, precipitation, horizontal distribution of trees, snowpack constitution and stability.

The charge separation of ice particles colliding with metals was investigated in a wind tunnel (air speed 10 m/s) at a temperature of —45°C for different metals as a function of an applied external electric field. The ice particles (to μm radius) collided with the metal target at a rate of 105 per second. The charge separation produced by different metals can be explained by the contact potential difference between the metal and the ice introducing electronic surface states on the ice. A lower limit for their density (1016m–2) is found. The influence of the electric field is explained by an interaction between Bjerrum defects and the electrons of the metal, the transfer probability depending on the charge in the surface states.

In x-ray irradiated single crystals of KCl, KBr, and KI doped in the melt with nitrate or nitrite, six triplets and one singlet are observed in electron paramagnetic resonance between -190\ifmmode^\circ\else\textdegree\fi{}C and room temperature. The trapping mechanism producing the centers is indicated by the behavior of the electron paramagnetic resonance signal during optical or thermal release of free electrons (from $F$ centers) or holes (from ${\mathrm{Cl}}_{2}^{\ensuremath{-}}$), and the chemical nature of the centers by selective doping methods. In all three salts these tests have identified NO interstitials (anisotropic up to room temperature, almost axial symmetry, principal paramagnetic axes in [100], [011], and [$0\overline{1}1$] directions); NO in positive-ion vacancies (isotropic); and N${\mathrm{O}}_{3}^{\ensuremath{-}\ensuremath{-}}$ in negative-ion vacancies (anisotropic below -145\ifmmode^\circ\else\textdegree\fi{}C, axial symmetry, axis in [111] direction). In KCl and KBr, N${\mathrm{O}}_{2}^{\ensuremath{-}\ensuremath{-}}$ in negative-ion vacancies (anisotropic, axial symmetry, axis in [110] direction, visible below -125\ifmmode^\circ\else\textdegree\fi{}C), and oxygen molecules (anisotropic, almost axial symmetry, axes in [100], [011], [$0\overline{1}1$] directions, visible below -100\ifmmode^\circ\else\textdegree\fi{}C) have been identified. Information regarding the bonding in the molecules has been obtained. Two isotropic triplets are not identified. The relative concentrations are different in the various host crystals, and the linewidth increases according to the halogen nuclear moment.

The theoretical distribution of impurities along a growing ice crystal is calculated for an arbitrary initial distribution in the liquid, and agrees qualitatively with results obtained with hydrofluoric acid. Stirring the liquid phase allows a satisfactory determination of the segregation coefficient for HF, NH3, and NH4F as a function of the concentration of the solution.

The 2 tortricoid moths attacking grapes in Europe, Eupoecilia (Clysia) ambiguella (Hb.) and Lobesia (Polychrosis) botrana Schiff. were among the first agricultural pests studied in sex pheromone research. Investigations by Gotz (1941a,b; for a complete bibliography see Jacobson, 1972) already concerned laboratory bioassay of the pheromone, use of clock traps to determine diurnal rhythms, and mass-trapping for control. The work was done explicitly with today’s objective: to do away with toxic chemicals. It is interesting to speculate whether the 30-year interruption in this line of work had more to do with wartime or simply with the advent of more effective insecticides.