Bent asymmetric dielectric slab waveguides: a detailed analysis.

Analytic expressions for the field and propagation constants of the mode along a uniformly curved three-layered slab waveguide are presented in terms of the power series of the curvature. To compare the accuracy of approximate solutions, numerical analysis is carried out. New bending loss formulas are also derived which consider the field deformation and the change of the propagation constant.

Bending losses in hollow and dielectric tube leaky waveguides.

A general method is presented of evaluating bending losses in hollow-core waveguides; analytic expressions are obtained for metallic hollow, dielectric hollow, and tube leaky waveguides on the basis of the 2-D slab waveguide model. Numerical examples are given for waveguides made of different kinds of metals, oxide, and dielectric materials at 10.6 microm.

Pulse spreading in a single-mode optical fiber due to third-order dispersion: effect of optical source bandwidth.

Pulse spreading in a single-mode optical fiber is discussed taking into account the third-order dispersion term of the waveguide when an optical source with a finite spectral width is modulated by a Gaussian-shaped pulse. Explicit forms for group velocity and pulse width are obtained taking into account both the optical source bandwidth and modulation bandwidth, and these are compared with those obtained by a simple theory. A condition is also made clear how small the second-order dispersion term has to be before the thirdorder dispersion term becomes important.

Increased integration of viral genome following chemical and viral treatment of hamster embryo cells.

Treatment of hamster embryo cells with diverse classes of chemical carcinogens enhances transformation by a carcinogenic simian adenovirus, SA7. Virus transformed foci selected from plates pretreated with 3-methyl-cholanthrene (MCA), methyl methanesulfonate (MMS) or 7,12-dimethylbenz[a]anthracene (DMBA) and established as cell lines in culture, contained equivalent amounts of SA7 viral genome. However, hamster embryo cultures treated with MMS or nickel sulfate had increased amounts of SA7 DNA integrated into cellular DNA when examined 2--9 days after chemical treatment and viral inoculation.

Pulse spreading in a single-mode fiber due to third-order dispersion.

Pulse spreading in a single-mode optical fiber is discussed taking into account the third-order dispersion term of the waveguide when the light source is modulated by a Gaussian pulse. A general expression for the pulse shape is analytically obtained, and an asymptotic approximation is used when the third-order dispersion term is small. It is also shown that the pulse width is no longer proportional to the guide length when the third-order dispersion term becomes large.

Reverse transcriptase from avian myeloblastosis virus.

From lots of 20 to 30 g of avian myeloblastosis virus RNA-dependent DNA polymerase was obtained in preparations of purity greater than 95% by using a two-step column chromatographic procedure employing DEAE (DE 52) and carboxymethylcellulose (CM 52.). Yields of RNA-dependent DNA polymerase varied from approximately 20,000 to 35,000 U/g of virus.

Measurement of mode conversion coefficients and mode dependent losses in a multimode fiber.

A new method for the simultaneous measurement of the loss and mode conversion coefficient in multimode fibers is proposed, which utilizes the differences of the mean transit time among modes. The principle is applied to a step-index fiber, and the mode conversion coefficient and mode dependent loss are obtained. A procedure to minimize the experimental errors is also discussed.

Protein kinase from avian myeloblastosis virus.

A protein kinase associated with purified virions of avian myeloblastosis BAI strain A was partially purified by ion-exchange chromatography and gel filtration. The transfer of phosphate catalyzed by this enzyme required a divalent metal ion and ATP as phosphate donor. GTP could not be substituted for ATP, and the reaction was unaffected by either cyclic AMP or beef-heart protein-kinase inhibitor.

Effects of butylated hydroxyanisole in Drosophila melanogaster.

The standard sex-linked recessive lethal test using "Basc" virgin females and treated Canton S males was used to test potential mutagenicity of ingested butylated hydroxyanisole (BHA) on mature spermatozoa. Ethyl methanesulfonate (EMS) was employed as a positive control and at lower concentrations a roughly linear dose response curve resulted. Flies treated with BHA yielded no higher frequency of sex-linked recessive lethals than did control flies, and statistical analysis confirmed that a high confidence level, the BHA treatment used did not double the spontaneous frequency of sex-linked recessive lethals.

Bending losses of dielectric slab optical waveguide with double or multiple claddings: theory.

Bending-loss formulas of a multilayer planar optical waveguide are obtained on the basis of continuation of wave functions without solving the complicated eigenvalue equation. We then consider the bending losses of a doubly clad slab waveguide in which the core has the largest refractive index, and the inner cladding has the lowest. Bending losses are shown to be drastically reduced by inserting low-index inner claddings between the core and the outer cladding.