Single Spacing Research Articles

Announcement

From January 1 1979 it will be mandatory for authors to supply with each paper a short abstract of 1–3 lines typed in single spacing. This must appear immediately after the address before the commencement of the paper. Keywords are no longer required.

Level Density Based on the Degenerate Single Particle Levels

Level density for the equidistant level scheme is derived with keeping the degeneracy of the single particle levels. The derivation is sufficiently accurate within the framework of the model, and the only approximation introduced is the saddle point approximation in the Darwin-Fowler integral. The results are discussed in comparison with those by the Rosenzweig approximation and those of the continuous approximations. It is found that the Rosenzweig approximation is accurate for a rather broad range of the nuclear temperature in the case of large systems. The deviation from the more accurate calculation appears only below the excitation energy of a few times the single particle level spacing. Discussion is presented on the quantitative relationship among the continuous approximation, the Rosenzweig model and the present method, in the light of the result of the level counting.

Induced moment magnetism in the cooperative Jahn-Teller systems: TbAsO 4 and TbVO 4

We have investigated the magnetic properties (magnetization, DC and AC susceptibility) of a new series of ternary rare-earth ruthenium germanides R2RuGe2, which crystallize in the monoclinic structure type Sc2CoSi2 (space group C2/m, No. 12). The two compounds containing yttrium or lanthanum are Pauli-type paramagnets. All the remaining compounds undergo ferromagnetic transitions, except Gd2RuGe2 and Tb2RuGe2, which seem to possess an antiferromagnetic ground state. The former finally exhibits a metamagnetic transition above 2 T and the latter, however, proves to be a highly anisotropic narrow domain wall ferromagnet, the critical field being close to 3 T. In the paramagnetic region the effective moments deduced are comparable with the ideal tripositive R3+ ion moments and the θp values are generally positive. The temperature dependence of the electrical resistivity is metallic like and reveals pronounced changes of slope near the ordering temperatures. The maxima of the dρ/dT versus T plots are in agreement with the magnetic data (Tord). The resistivity of Ce2RuGe2 was found to be determined by an interplay of Kondo scattering and crystal-field effects. The temperature dependence of the spin disorder resistivity in the paramagnetic regime for the remaining samples could be attributed to the influence of the crystalline field split 4f levels. Not knowing the exact level schemes, we use a single spacing (δ) crystal-field model for an order of magnitude estimate.

Row Spacing and Potential Productivity in Sugarcane1

AbstractSugarcane (Saccharum spp. hybrid) has been reported to respond only slightly to reduced interrow spacing. However, commercial cultivars are released after 10 to 15 years selection at a single row spacing and would be expected to be suited to that particular spacing. To determine if sugarcane has the genetic potential to exhibit increased productivity at high stalk populations, the performance of unselected seedlings was compared with that of commercial cultivars at several planting densities (2.6 to 32 setts/m2) and interrow spacings (25 to 140 cm). Comparisons were made over a 2‐year period in small scale field trials and in pot culture.Reduction of the interrow spacing from 140 to 50 cm significantly increased the yield of some cultivars in an irrigated field trial. The superiority of close row spacing treatments was maintained when the ratoons were grown under natural rainfall.About 7% of an unselected seedling population planted at high density (32 setts/m2) in pot culture performed better than commercial cultivars planted at the same or lower (5 setts/m2) density. Clones which gave superior yields at high planting density were not significantly better than other seedling or commercial clones when grown at conventional planting density. Consequently, exploitation of increased productivity due to reduced interrow spacing should involve selection at the row spacing adopted.

YIELD RESPONSE OF SPRING BARLEY TO ROW SPACING AND SEEDING RATE

Four cultivars of Hordeum vulgare L. were grown in 1967 at three seeding rates (54, 108, and 161 kg/ha) in six row spacings (11-, 18-, 23-, and 31-cm rows, and 11- and 18-cm cross-planted rows). The study was expanded in 1968 to include an additional cultivar of Hordeum distichum L. Grain yield was unaffected by seeding rate in either year. Narrow row spacing resulted in increased grain yields in 1968, when mean yields were high, but not in 1967 when yields were below normal. In both years, decreased row width resulted in increased numbers of spikes per m2 of ground area, and decreased numbers of grains per spike. A significant cultivar × row spacing interaction for yield was observed in 1968, but not in 1967. Statistical analysis revealed this interaction to be closely related to cultivar yield levels; that is, high yielding cultivars displayed a greater response to narrowing row spacing than did their lower-yielding counterparts. No consistent relationship was observed between cultivar yield differences, or the cultivar × row spacing interaction for yield, and cultivar differences in morphological type (leaf disposition, plant height). Furthermore, cultivar differences in yield were not related to the relative size of the various yield components (1000-grain weight, grains per spike, and spikes per m2). Although a cultivar × row spacing interaction for yield was observed, results suggest that, under Ontario conditions, this interaction does not represent a serious drawback to present cultivar testing procedures whereby cultivars are evaluated for yield at a single row width spacing.

Neutron evaporation and level densities in excited nuclei

The theory of a cascade neutron evaporation process is derived in detail in a form suited to the treatment of highly excited nuclei which have a continuous distribution of excitation energies following a primary direct interaction. The results are found to give good agreement with neutron spectra of nuclei following bombardment with 190 MeV protons observed by Gross. Data from medium energy neutron reactions, thermal energy neutron resonances, and heavy ion reaction experiments are compared. Formulae are derived in an appendix for the effect on the level density of a gap in the single particle level spacing at the Fermi level.

Atom movements and dislocation structures for plastic slip in single crystals of β-uranium

The crystallographic elements of slip in single crystals of β-uranium have been interpreted in terms of formalized atom movements compatible with the structural characteristics of the crystal, and dislocation structures for accomplishing the movements have been derived. A novel and critical part of the general problem lies in the fact that the unit cell of the simple tetragonal lattice contains the relatively large number of thirty atoms, which are arranged in a sufficiently complex manner to obscure any ready identification of a slip interface. The structure of the crystal is described in detail and the over-all structural requirements of any deformation model are deduced. It is then shown that the structure permits a flow process based on a double interface, i.e. the slipping portions of crystal are separated by a volume or zone of atoms which is needed to maintain structural continuity during the flow process. The width of the zone corresponds to a single lattice spacing normal to the observed slip plane of the lattice. The body of the paper is concerned with the development and description of the associated process of plastic flow.

Thermal properties of fats and oils

1. Melting points and x-ray diffraction patterns have been determined for cottonseed oil hydrogenated to an iodine value of less than 1, and for a very pure sample of tristearin. 2. Contrary to the observations of previous investigators, the x-ray patterns indicate a well-defined crystal structure with a sharp long spacing and a single sharp short spacing in the lowest-melting form of tristearin. A new pattern, with two short spacings and a long spacing, was observed in tristearin of intermediate melting point. 3. Four polymorphic forms of the hydrogenated cottonseed oil were detected. The x-ray pattern of the lowest-melting form of the hydrogenated oil was similar to that of the correspopnding form of tristearin. The pattern of the highest-melting form of the hydrogenated oil differed from that of either tristearin or β-palmitodistearin, the major components of the oil. Distinctive patterns for the intermediate forms of the hydrogenated oil could not be obtained, presumably because of the instability of the lower melting forms at room temperature.