Cytogenetic studies in North American minnows (Cyprinidae). IV. Somatic polyploidy in Gila bicolor

The kidney tissue of a single individual of the California minnow Gila bicolor (Girard) contained polyploid cells in about 1.7% frequency. Chromosome spreads of triploid, tetraploid, hexaploid, octaploid, and dodecaploid cells were observed and may have arisen through endoreduplication of ancestral diploid and triploid cells. The cytological mechanism producing the triploid cells is unknown. Diplochromosomes were not present. The distribution of ploidy in cells of this individual is not random. In particular, cells having undergone one round of chromosomal increase appear increasingly susceptible to additional rounds of chromosomal gain

Spontaneous triploidy in the California roach Hesperoleucus symmetricus (Pisces: Cyprinidae).

A single triploid individual (3n = 75) of the Calfornia roach, Hesperoleucus symmetricus, was identified among a sample of nine specimens from the Russian River, California. The diploid number of H. symmetricus, as revealed by the karyotypes of the remaining eight specimens, is 50. Aside from the all-female triploid unisexual fishes, this is the first report of a triploid fish from the wild, and the second report of a triploid in a bisexual fish species. The most likely origin of the triploid was probably fusion of a haploid sperm with an unreduced ovum

Genome size variation and evolution in North American cyprinid fishes

International audienc

Classifying the Arithmetical Complexity of Teaching Models

This paper classifies the complexity of various teaching models by their position in the arithmetical hierarchy. In particular, we determine the arithmetical complexity of the index sets of the following classes: (1) the class of uniformly r.e. families with finite teaching dimension, and (2) the class of uniformly r.e. families with finite positive recursive teaching dimension witnessed by a uniformly r.e. teaching sequence. We also derive the arithmetical complexity of several other decision problems in teaching, such as the problem of deciding, given an effective coding $\{\mathcal L_0,\mathcal L_1,\mathcal L_2,\ldots\}$ of all uniformly r.e. families, any $e$ such that $\mathcal L_e = \{L^e_0,L^e_1,\ldots,\}$, any $i$ and $d$, whether or not the teaching dimension of $L^e_i$ with respect to $\mathcal L_e$ is upper bounded by $d$.Comment: 15 pages in International Conference on Algorithmic Learning Theory, 201

Book Reviews

THE SILVERLAKE EXPERIMENT. By Lamar T. Empey and Steven G. Lubeck. Chicago: Aldine Publishing Company, 1971. Pp. x, 354. $12.50. THE FEAR OF CONSPIRACY: IMAGES OF UN-AMERICAN SUBVERSION FROM THE REVOLUTION TO THE PRESENT. Edited with commentary by David Brion Davis.Ithaca: Cornell University Press, 1971. Pp. xxiv, 362.$10.00. THE INTERNATIONAL LAW OF CIVIL WAR. Edited by Richard A. Falk. Baltimore: The Johns Hopkins Press, 1971. Pp. xix, 452. $15.00. THE DEATH OF THE GREAT SPIRIT: AN ELEGY FOR THE AMERICAN INDIAN. By Earl Shorris. New York: Simon and Schuster, 1971. Pp. 253.$6.95

Bed Bugs

2 pp., 1 illustrationBed bugs infest beds, bedding and furniture and feed on the blood of humans. This publication explains how to identify bed bugs, how to locate infestations and how to control these pests

Innovative interstellar explorer

An interstellar "precursor" mission has been under discussion in the scientific community for at least 30 years. Fundamental scientific questions about the interaction of the Sun with the interstellar medium can only be answered with in situ measurements that such a mission can provide. The Innovative Interstellar Explorer (IIE) and its use of Radioisotope Electric Propulsion (REP) is being studied under a NASA "Vision Mission" grant. Speed is provided by a combination of a high-energy launch, using current launch vehicle technology, a Jupiter gravity assist, and long-term, low-thrust, continuous acceleration provided by an ion thruster running off electricity provided by advanced radioisotope electric generators. A payload of ten instruments with an aggregate mass of ~35 kg and requiring ~30 W has been carefully chosen to address the compelling science questions. The nominal 20-day launch window opens on 22 October 2014 followed by a Jupiter gravity assist on 5 February 2016. The REP system accelerates the spacecraft to a "burnout" speed of 7.8 AU per year at 104 AU on 13 October 2032 (Voyager 1's current speed is ~3.6 AU/yr). The spacecraft will return at least 500 bits per second from at least 200 AU ~30 years after launch. Additional (backup) launch opportunities occur every 13 months to early 2018. In addition to addressing basic heliospheric science, the mission will ensure continued information on the far-heliospheric galactic cosmic ray population after the Voyagers have fallen silent and as the era of human Mars exploration begins

Richard P. Feynman 1918-1988

Richard Feynman, simply put, was a genius. His quick wit and uncommon grasp of physics meant that any research area he encountered, he quickly mastered. Despite the fact that his own area of research was not geophysics, his life and work influenced almost all of us. Virtually every physics graduate student who started in the mid 60s or later was exposed to his Lectures on Physics, either by having them as a text for a course or by using them (as I did) to bone up for oral qualifying exams. Feynman diagrams appear in nearly every modern quantum mechanics textbook and are featured in his official Caltech portrait, which illustrates this article

Drywood Termites

6 pp., 5 illustrations, 6 photosDrywood termites feed on wood and damage homes and other structures throughout the southern portion of the United States. Evidence of infestation includes swarming termites inside a home and the presence of fecal pellets. This publication explains how to conduct a thorough inspection for termites and the various options for treating infestations