Eurycea wilderae

Number of Pages: 4Integrative BiologyGeological Science

Ultrastructure of the reproductive system of the black swamp snake (\u3ci\u3eSeminatrix pygaea\u3c/i\u3e). Part III. The sexual segment of the male kidney.

In mature male snakes and lizards, a distal portion of the nephron is hypertrophied in relation to its appearance in females and immature males. This sexual segment of the male kidney apparently provides seminal fluid that is mixed with sperm and released into the female cloaca during copulation. In this article, we provide the first study at the ultrastructural level of seasonal variation in the sexual segment of the kidney of a squamate, the natricine snake Seminatrix pygaea. Previous workers have indicated that the sexual segment is secretory only when the testes are spermatogenically active. The sexual segment of the kidney in S. pygaea does not go through an extended period of inactivity but does show a cycle of synthesis and secretion that can be related to the spermatogenic cycle and mating activity. We show that synthesis of secretory product is initiated with the onset of spermatogenic activity in the spring and culminates with completion of spermiation in the fall. Secretion of the product, however, occurs in a premating period in March when the testes are inactive. Secretion during this premating period is probably necessary to provide time for the passage of the products down the ureter in order to mix with spermduring mating later in spring

Eurycea junaluska

Number of Pages: 2Integrative BiologyGeological Science

Bound states of a more general exponential screened Coulomb potential

An alternative approximation scheme has been used in solving the Schrodinger equation to the more general case of exponential screened Coulomb potential, V(r)=-(a/r)\[1+(1+br)e^{-2br}]. The bound state energies of the 1s, $2s, and 3s-states, together with the ground state wave function are obtained analytically upto the second perturbation term.Comment: 14 page

A perturbative treatment for the bound states of the Hellmann potential

A new approximation formalism is applied to study the bound states of the Hellmann potential, which represents the superposition of the attractive Coulomb potential $-a/r$ and the Yukawa potential $b\exp (-\delta r)/r$ of arbitrary strength $b$ and screening parameter $\delta$. Although the analytic expressions for the energy eigenvalues $E_{n,l\text{}}$ yield quite accurate results for a wide range of $n,\ell$ in the limit of very weak screening, the results become gradually worse as the strength $b$ and the screening coefficient $\delta$ increase. This is because that the expansion parameter is not sufficiently small enough to guarantee the convergence of the expansion series for the energy levels.Comment: 25 page

Exact Polynomial Eigensolutions of the Schrodinger Equation for the Pseudoharmonic Potential

The polynomial solution of the Schrodinger equation for the Pseudoharmonic potential is found for any arbitrary angular momentum $l$. The exact bound-state energy eigenvalues and the corresponding eigen functions are analytically calculated. The energy states for several diatomic molecular systems are calculated numerically for various principal and angular quantum numbers. By a proper transformation, this problem is also solved very simply by using the known eigensolutions of anharmonic oscillator potential.Comment: 10 page