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Es wurde der Einflus ebener Versetzungsanordnungen auf das Eindringen dazu senkrechten Magnetflusses in supraleitende Niobeinkristalle bei 4,2°K experimentell untersucht. Die Dichte der Versetzungen ϱ wurde mittels Atzgrubchen und Elektronentransmission bestimmt. In einem einfachen Modell kann aus der Remanenz der gemessenen Hysteresekurve auf die Kraft geschlossen werden, die einen Abrikosovschen Flusfaden Versetzungen schneiden last. Diese Kraft liegt fur Versetzungsdichten von 2 · 106 bis 5 · 1010 cm−2 zwischen 4 · 10−7 und 1,4 · 10−4 dyn/cm und ist proportional √ϱ. Ferner wurden die Auswirkungen verschiedener Oberflachenbehandlungen auf die Magnetisierungskurve verfolgt und modellmasig interpretiert. Die Wechselwirkung zwischen Flusfaden und Oberflachen fuhrt zu einer Hysterese, nicht aber zu einer Remanenz. A study is made of the effect of planar arrays of dislocations on flux penetration into niobium single crystals at 4.2°K. The dislocation densities ϱ are measured by etch pits and by electron transmission. The measured hysteresis, (in particular trapped flux,) is used to calculate the interaction force between an Abrikosov flux line and the dislocations lying perpendicular to it. For ϱ between 2 × 106 and 5 × 1010 cm−2 the measured interaction force varies between 4 × 10−7 and 1.4 × 10−4 dynes/cm, and it is proportional to √ϱ. The interaction between flux lines and surfaces is studied following various surface treatments. In agreement with simple theory this interaction leads to hysteresis without trapped flux.

The electrophotographic properties of pink zinc oxide powder embedded in silicone resin have been investigated in a standard measuring unit with a sample holder on a turntable, a translucent measuring probe, and a corona discharge in a vacuum box. The charging and subsequent discharging in the dark and under illumination have been recorded. From these curves, the half-life of the light-decay of pink zinc oxide layers was evaluated. Depending on a suitable preparation, the layers exhibited a negative charging up to —850 V and a positive charging up to 500 V. As could be demonstrated, both the dark-decay and the speed of the light discharge of some layers were comparable with electrofax paper available on the market for reprographic purposes. The remaining residual charge, however, is at present larger than that of electrofax paper. This larger residual voltage of the layers, however, can be possibly caused by the rather large portion of resin in the layers. The spectral dependence of the photocurrent of the pink zinc oxide resin layers exhibits two maxima, one at 490 and the other at 585 nm caused by the remission maximum and the fluorescence, respectively. Zur Untersuchung der elektrophotographischen Eigenschaften von rotem ZnO wurden verschiedene ZnO-Siliconharz-Schichten hergestellt und in einer geeigneten Meszelle einer Coronaentladung unterworfen. Die dabei erzielte Aufladung und anschliesende Entladung wurde mit und ohne Einstrahlung von sichtbarem Licht gemessen. Die Schichten zeigten bei geeigneter Praparation eine positive Aufladung von 500 V und eine negative Aufladung bis —850 V. Sowohl die Dunkelentladung als auch die Photoempfindlichkeit mancher Schichten ist den Eigenschaften von kauflichem ZnO-Papier fur Reproduktionszwecke durchaus vergleichbar, allerdings ist die verbleibende Restladung hoher. Die spektrale Abhangigkeit des Photostromes zeigt zwei Maxima bei 490 und 585 nm, der Wellenlange des Remissions-Maximums bzw. der Fluoreszenz von rotem ZnO.

Die optischen Eigenschaften von Versetzungen in Ge wurden durch Messungen des Spektrums und der Temperaturabhangigkeit von Photoleitung und Photohalleffekt an verformten Ge-Proben untersucht. Durch Korrelation der beiden Mesverfahren war es moglich, die Art der angeregten Ladungstrager zu bestimmen. Die Messungen weisen darauf hin, das im gesamten Spektralbereich von 0,1 bis 0,8 eV Zustande an den Versetzungen angeregt werden. Die dabei auftretenden Beweglichkeitsanderungen konnen bis zu 2/3 des Photoleitungssignals ausmachen. Zur Interpretation der Messungen wird ein Modell vorgeschlagen, welches von der Existenz zweier Versetzungsbander in der Bandlucke ausgeht. Dieses Modell ist im Einklang mit den elektrischen Messungen; es wird ausfuhrlich in einer nach-folgenden Veroffentlichung diskutiert. An investigation was made of the optical properties of dislocations in Ge measuring the spectral and temperature dependences of photoconductivity and photo-Hall effect on deformed Ge-samples. Correlating the results of both the measuring techniques it was possible to determine the kind of excited carrier. The results suggest that states at the dislocations are excited in the whole spectral region of 0.1 to 0.8 eV. Mobility changes are found of up to 2/3 of the photoconductivity signal. A model proposed to explain the measurements, assuming the existence of two dislocation bands in the gap is in agreement with the electrical measurements and will be discussed in detail in a forthcoming paper.

This paper presents a method of numerical solution of boundary value problems governed by a set of ordinary differential equations. The highest derivative is chosen as the unknown function. Governing equations are transformed into a set of integral equations. The kernels of integral equations turn out to be influence functions for deflection and/or bending moments of a corresponding beam, and can, therefore, be computed using well-known methods of structural analysis. Finally, the unknown function (highest derivative) is approximated in a defined manner and the solution is obtained through numerical integration.

Clarkia rhomboidea Douglas (Onagraceae) is a widely distributed western North American annual of polyploid origin (Lewis and Lewis, 1955; Mosquin, 1961). Studies of meiotic associations of chromosomes in artificial interpopulational hybrids of this species indicate that since its origin a considerable amount of chromosomal reorganization has occurred among natural populations. The chromosomes have been altered both by reciprocal translocations and paracentric inversions. The purpose of this paper is to examine the evidence for the origin of C. rhomboidea and to determine the subsequent course of chromosomal differentiation in this species. When considered together with the recent climatic history of the western United States, the cytogenetic information provides unusual clues to the recent changes in distribution pattern and paths of migration followed by C. rhomboidea since its origin. Clarkia rhomboidea ranges from the mountains of southern California northward in a broad belt following the Sierra Nevada, the Coast Ranges, and the Cascade Range to Washington and extends eastward into Idaho. Widely disjunct populations occur in Utah and Arizona. The species is absent from the southwestern deserts and the arid interior of Oregon and Washington (fig. 1). The populations are adapted to a wide range of habitats. In Arizona, Utah, Nevada, and most of California they occur in the broad transition zone between the Arcto-Tertiary and the Madro-Tertiary Geofloras associated usually with yellow pine (Pinus ponderosa) and various oaks. However, from the higher elevations of the Sierra Nevada in California to the northern limits of the species range, the colonies are generally found in coniferous or montane forest. The wide range of ecological tolerance is especially evident on the western slopes of the Sierra Nevada of California where populations occur from the mesic margins of montane meadows at 10,000 feet elevation to the arid oak woodland and chaparral associations at about 1,800 feet. Plants of this species tend to be colonial with populations varying in size from a few individuals to many hundreds. However, single plants and small colonies often occur sporadically over many miles of favorable terrain. Herbarium specimens as well as field and garden observations indicate that interpopulational variation is especially pronounced in this species (Lewis and Lewis, 1955; Mosquin, 1961). The most conspicuous variables are flowering time, habit, leaf and petal shape, and flower size. With respect to breeding habit, populations with small flowers are automatic selfers whereas those with larger flowers tend to be outcrossed. The chief pollinators are various Hymenoptera. The plants are self-compatible and capsules of most plants set a full complement of seed when isolated from insects. As in other species of Clarkia, the seeds have no mechanism for longrange dispersal and are as a rule dropped near the parent plant. The chromosome number in C. rhomboidea is n = 12 and is based upon an examination of 74 plants from 47 populations 1 This investigation was carried out while the writer was a graduate student at the Department of Botany, University of California, Los Angeles, and is a portion of a dissertation submitted as part of the requirements for the degree of Doctor of PhilosoDhv.