Optimal administration of dual screening tests for detecting a characteristic with special reference to low prevalence diseases.

We consider the problem of deciding optimally whether a characteristic exists based on one or two screening tests. We discuss the relative merits of giving either one or two tests, including the order in which they might be given, as well as their costs. Operating in the Bayesian mode, we derive posterior distributions for the accuracies of the tests and the prevalence of the characteristic. Applications to detecting rare conditions, such as the AIDS virus, are discussed.     

Location of chloroplast membrane resonances in high resolution 13C-NMR spectrum of spinach leaves.

Spinach leaves were studied by high resolution 13C-NMR spectroscopy. The spectra obtained, though highly complex, showed some distinct resonances assignable to carbons of lipids of the chloroplast membranes, thereby offering a novel way for studying the chloroplast membranes in situ.     

Free flaps in the elderly.

Microsurgical transfer of tissue has become a primary tool of the reconstructive surgeon. The elderly, as a growing segment of our society, are requiring free-tissue transfers in proportion to their numbers. To investigate the potential morbidity of free-tissue transfers in the elderly, we studied consecutive populations of 31 patients above the age of 65 years and 90 patients below the age of 65 years. Complication rates were 65 and 49 percent, respectively. Premorbid medical conditions were present in 87 percent of patients 65 years and older and in 72 percent of those under 65 years. Medically related complications in free-tissue transfers, previously unreported in the literature, were 35 percent in the elderly group and 10 percent in the younger group. Wound-healing complications were seen in equal proportions between groups. The rates of wound and medically related complications observed in the elderly group were nearly double those observed in the younger group; however, after correction for the presence of preexisting medical conditions, no significant differences were seen between the two groups. These observations suggest that age alone is not a variable in risk for free-tissue transfers. Elective microsurgery can be performed in the elderly patient with a high expectation of success.     

A new species of Pseudopecoelus von Wicklen, 1946 (Digenea: Opecoelidae) from the orange roughy Hoplostethus atlanticus Collett, 1889 (Trachichthyidae) from off southeastern Australia

A new species, Pseudopecoelus sewelli, is described from the deep-sea fish Hoplostethus atlanticus from off southeastern Australia. It is an elongate form with considerable variation in such important characters as the anterior vitelline extent, the sucker ratio and the egg-size. The features distinguishing this species from five related forms are combinations of the sucker ratio, egg-size, lobation of gonads, presence or absence of a cirrus-sac and the position of the genital pore.     

Heterostyly and Pollen-tube Interactions in Luculia gratissima (Rubiaceae)

Observations on the floral biology of Luculia gratissima (Rubiaceae)showed that this species is distylous with complementary positioningof anthers and stigmas in the two floral forms. Unusual featuresof distyly in this species include the larger size of the corolla,the stigma surface and the stigmatic papillae in the thrum flowerscompared to the pin ones. Stigmatic surfaces have similar secretionsbut they appear more copious in thrum than pin. The floral dimorphismwas accompanied by a very effective self-incompatibility systemand no seed was set on selfing. Seed number per capsule on crossingwas significantly greater in thrum flowers compared to pin.Incompatible pollen tubes were inhibited within 24 h at thebase of the stigma/top of the style in both morphs. Amputationof this region of the gynoecium removed the self-incompatibilityreaction in thrum but not pin flowers. Pollination with a mixtureof compatible and incompatible pollen and sequential pollinationwith self followed by cross pollen showed that there were interactionsbetween the two types of pollen tube. The presence of compatibletubes was found to cause the excessive swelling of the pollen-tubetip of the incompatible ones. The incompatible tubes did notappear to have any effect on the growth of compatible ones. Luculia gratissima, distyly, floral biology, self-incompatibility, pollen-tube interactions