Study of the dependence of 198Au half-life on source geometry

We report the results of an experiment to determine whether the half-life of \Au{198} depends on the shape of the source. This study was motivated by recent suggestions that nuclear decay rates may be affected by solar activity, perhaps arising from solar neutrinos. If this were the case then the $\beta$-decay rates, or half-lives, of a thin foil sample and a spherical sample of gold of the same mass and activity could be different. We find for \Au{198}, $(T_{1/2})_{\rm foil}/(T_{1/2})_{\rm sphere} = 0.999 \pm 0.002$, where $T_{1/2}$ is the mean half-life. The maximum neutrino flux at the sample in our experiments was several times greater than the flux of solar neutrinos at the surface of the Earth. We show that this increase in flux leads to a significant improvement in the limits that can be inferred on a possible solar contribution to nuclear decays.Comment: 5 pages, 1 figur

Hereditary correlation of size and color characteristics in tomatoes

From the hereditary standpoint, color and size characters in either plants or animals are not equally well understood. In general, the inheritance of color, technically known as a qualitative character, has been rather satisfactorily determined. On the modern chromosome theory of heredity, the genetic factors responsible for the development of colors appear to be located on the various chromosomes of the species and apparently follow a regular, stable and predictable mode of inheritance from generation to generation. Environmental agencies play a relatively minor part in ;modifying such characters. It is for this reason, perhaps, that their inheritance has been so thoroly investigated

Inheritance of Fruit Shapes and Sizes in the Pepper and Tomato

Both Capsicum and Lycopersicum exhibit the same correlation between fruit shape and fruit size, a correlation which is wholly lacking for the same characters in the Cucurbits. In the pepper both positive and negative correlations of shape and size were discovered in F2 generations, the sign of the correlation being dependent on the parental combinations. Accordingly the cause for the correlations must be the genetic one of linkage, due to the presence of shape and size genes on the same chromosome, a fact which has already been reported for the tomato. Fruit sizes in both genera exhibit logarithmic rather than additive distributions

Genetic Stability of Tomato Diploids and Tetraploids Derived from Haploid

By doubling the chromosomes of a haploid tomato asexually (decapitation-callus technique) an absolutely homozygous diploid is produced. Ten generations of severe selection to break this pure line have resulted only in very minor changes, easily attributable to a normal mutation rate. Data on the effect of the selection pressure on dry weight of plants and on size and weight of fruits show no statistically significant effects in two selection lines and a barely significant ( 5 per cent point) effect in a third selection line. Only one major point-mutation was noted among the 12,000 experimental plants (a mutation to a recessive wiry form, different genetically from the original wiry mutant) and this occurred in the control lines. These results are directly opposed to the Russian worker, Lysenko\u27s claims that the tomato deteriorates in three to five generations. The original haploid, now carried on asexually for 12 years, has proved also to be remarkably stable, only one large bud-sport having been observed

Fruit Size and Shape Genes on the First Chromosome of the Tomato

Genetic evidence has demonstrated the presence of a major factor for fruit size in the first linkage group of the tomato, linked inheritance being exhibited between fruit size and the genes for the tall-dwarf and the smooth-peach (pubescent) characters. In this same linkage group a major gene for fruit shape (ovate) has been found

Alpha-beta pruning on evolving game trees

technical reportThe alpha-beta strategy is a widely used method for economizing on the size of game trees. Heretofore, its application has been limited to depth-first tree growth in recursive search functions. However, many modern game players use retentive (i.e. coroutine-based) control to achieve greater attention mobility in the game tree, e.g. for heuristically guided "best-first" searching. This paper reformulates the alpha-beta strategy for this generalized control setting. Algorithms are provided (in complete PASCAL code) for the following operations on appropriate nodes arbitrarily selected from a game tree: terminal node expansion, resumption of heuristically suspended move generation, tree re-rooting (i.e. top-level move selection), subtree redevelopment to satisfy a new search thoroughness condition, including restart of nodes that were cut-off but may no longer be. empirical results are presented indicating that, in addition to heuristic freedom, this method typically offers trees with fewer terminal nodes than in the recursive case, due to best-first descendant ordering, and the availability on the average of greater tree context for node cutting