Spatial Replication Research Articles

The nuclear matrix--its role in the spatial organization and replication of eukaryotic DNA.

The nuclear matrix--its role in the spatial organization and replication of eukaryotic DNA.

Multifactorial analyses of directions of movement of animals

Analyses of the orientations and movements of animals require multifactorial experiments to differentiate among complex, interacting influences. There are no statistical procedures for the analysis of multifactorial sets of angular data. As a result, many studies have inadequate spatial replication, or confound several potential sources of variation. In this paper, methods are described for the analysis of complex multifactorial sets of angular data. Analogues of techniques of analysis of variance are demonstrated that allow partitioning of the resultant vectors of sets of angular data to serve as a basis for tests of significance. Resultants are partitioned into components corresponding to any identifiable or planned source of variation in the experiment, allowing hierarchical, factorial and mixed experimental designs (as with linear models for analyses of variance). Because the statistical properties of these partitions are at present unknown, significance tests are then done by randomization procedures on each set of data. The randomizations produce an empirical distribution of a test statistic (in this case, analogous to F-ratios in linear analyses of variance), against which the calculated statistic for the given set of data can be compared. These techniques are illustrated for experiments on the directions of movement of a small intertidal snail, Littorina unifasciata Gray, on sandstone shores in New South Wales. Various experimental designs are discussed, including two and three experimental factors, in nested and orthogonal analyses. The results revealed that the movements of this species are influenced by many factors, and that the effects of these vary from time to time and place to place on the shore. The complexity of these results is discussed with respect to previous, simpler experiments about movements of gastropods. The potential advantages of multifactorial comparisons using the methods described here are indicated for various aspects of the study of directional movements of intertidal snails.

Spruce Spider Mite Control, 1981

Abstract A 1980 study showed that 1.5 oz/gal or 3.0 oz/gal of Safer’s Insecticidal Soap applied by backpack blower or hydraulic sprayer was efficacious for controlling spruce spider mites. The present study was a temporal and spatial replication of the lower application rate (1.5 oz/gal) applied by both backpack mist blower and hydraulic sprayer. Approximately 300 trees at the Mountain Research Station, Waynesville, NC were divided into 6 blocks. Two blocks were randomly selected as controls while the remaining blocks were treated with 1.5 oz/gal of soap and applied with a Solo backpack mist blower. Ten, 5-cm twig samples were taken from the center of each plot and analyzed for eggs, larvae, nymphs and adults of the spruce spider mite. Twig samples were taken before treatment and 1, 2, and 4 wks after treatment. Two 50-tree plots, in Ashe County, NC, were divided into 2 blocks each. Each plot had a treated block and a control block. The treated blocks were sprayed by hydraulic sprayer with 1.5 oz/gal of soap. One, 5-cm twig sample was taken from each tree in all 4 blocks and analyzed for eggs, larvae, nymphs, and adults of the spruce spider mite. Twig samples were taken before treatment and 1 and 3 wk after treatment.

Spatial replication in back-propagated acoustic holograms

Acoustic holograms may be reconstructed digitally by the method of backward wave propagation. The images may be distorted by spatial replication, caused by the use of two discrete Fourier transforms (DFT's) in sequence to produce the image. This phenomenon is illustrated and explained, as is a method to prevent the distortion.