In recent years the black cutworm, Agrotis ypsilon (Rott.), has been the predominant species of economic importance in southwestern Ontario. Relatively small populations of this insect can cause extensive damage to widely-spaced cash crops such as tobacco, tomatoes, and sugar beets.

Present control recommendations are based primarily on results obtained from field trials. These results are often inconclusive because cutworm outbreaks are difficult to predict and usually unevenly distributed. Therefore, it is necessary to develop laboratory techniques to assist in assessing the comparative toxicity of insecticides and their formulations.

A number of techniques have been developed for rearing cutworms of economic importance. Most of those that were developed primarily for lifehistory studies (Crumb, 1929; Hocking, 1952; King and Atkinson, 1927; Satterthwait, 1933; Snyder, 1954) are unsatisfactory for mass rearing. Mass rearing techniques have been developed for several cutworms of economic importance (Jacobson and Blakeley, 1957; Swingle et al., 1941; Waters, 1937; and Wylie and Palm, 1940). However, the black cutworm, Agrotis ypsilon (Rott.), is difficult to rear because of cannibalism.

The black cutworm, Agrotis ipsilon (Hufnagel), is of major economic importance in many areas of the world. In recent years, adequate methods for assessing the toxicity of insecticides to the black cutworm have been developed (Begg and Harris, 1958; Begg et al., in preparation; Harris and Mazurek, 1961). However, with the exception of the works by Crumb (1929) and Satterthwait (1933), less research has been devoted to the life history of this insect.

We compared the results of the tuberculin skin test with the results of the QuantiFERON-TB Gold In-Tube (QFT-GIT) assay among 182 low-risk healthcare workers. Overall agreement and specificity were high, but the tests did not agree on positive results. Only 2 of 5 positive QFT-GIT assay results could be confirmed with repeat analyses. Indeterminate results were associated with potential immunosuppression.

In 1994 a Texas prison containing a population of mentally retarded inmates experienced a large tuberculosis outbreak. Fifteen cases of tuberculosis were identified (8 confirmed by positive cultures for Mycobacterium tuberculosis) and more than 100 inmates became infected. The culture-confirmed patients were infected with an identical strain of tuberculosis as demonstrated by polymerase chain reaction (PCR) based DNA fingerprinting technique. The prison followed standard tuberculosis infection control policies, but these controls were inadequate to prevent tuberculosis transmission in this special population. Two hundred and thirty inmates (119 inmates showing evidence of new tuberculosis infection or active disease and 111 healthy controls) were enrolled in the investigation. Inmate cell assignments, job duties, and educational classes were identified and medical chart reviews were conducted on all inmates. Tuberculosis transmission was associated with residing on the D Wing of the prison (OR = 25·84, P < 0·01), attending school in Classroom A (OR = 8·34, P = 0·01) and working on the prison utility work crew (OR = 2·52, P < 0·01). The index case in the outbreak had been prescribed 6 months of isoniazid (INH) chemoprophylaxis in 1988.

The aim was to evaluate hepatitis C surveillance in Poland during 1998. Hepatitis C reports were obtained from epidemiology offices. Public health staff were interviewed to collect information on surveillance operations. To estimate the proportion of acute cases among the total reported, a study was conducted in the Warsaw district to validate case reports. A total of 1661 (97.2%) hepatitis C cases were studied. Hepatitis C surveillance was timely and acceptable to the user, but did not provide a number of information elements required to differentiate acute from chronic cases of infection. Of the 268 case reports available in the Warsaw district, only 15 (5.6%) met the acute hepatitis C case definition. It is concluded that hepatitis C surveillance in Poland cannot provide useful incidence estimates and information regarding risk factors for acute infection. A strict case definition and a modified case form with specific questions for HCV transmission routes should be applied.

In the synthesis of polyacrylates, a necessary step involves the conversion of acroleins to acrylic acids- a process catalysed by Mo oxides. We have directed our work towards the elucidation of the electronic structure of the most stable structure of 12-heteromolybdate, ie. the α-keggin unit, using EPR spectroscopy, Cyclic Voltammetry, and molecular orbital calculations based on the extended Huckel theory. Metal ion substitution has been shown to have negligible effect on the electronic structure of the keggin unit thus rationalising previous arguments of structural rigidity. Electronic exchange has been shown to be facilitated through metal-metal interaction.

The collapse of dense cores in massive stars proceeds as follows. Initially, leptons dominate the pressure because neutrinos become trapped at high densities. This results in the formation of a cool inner core that collapses homologously. At around nuclear densities the pressure from nucleons increases rapidly and halts the collapse, giving a core bounce. A shock forms at the surface of the inner core and propagates into the infalling envelope. These basic features have emerged in the hydrodynamic studies of collapse by various researchers. However, the question of final outcome of collapse is unresolved at present. The evolution of the core after the shock has propagated through the envelope has not been addressed in detail. This communication summarizes some current results of the author's ongoing study of stellar collapse.

The rapid mass loss observed in O stars can affect their evolution dramatically if it takes place during core hydrogen burning on the main sequence. Conti has suggested that this is the case for the brightest Of stars, and that these stars evolve into Wolf-Rayet (WR) stars. Support for this scenario comes from the similarity in the spectra of the Of and WR stars, and from the observed helium enrichment of Wolf-Rayet WN stars along with the correlation of the latter with the most luminous O stars. If the most massive Of stars evolve to WN stars of relatively low mass, one needs to determine the range of zero-age stellar masses where such an evolution occurs. This communication abstracts some observational evidence that bears on the question of the minimum zero-age mass for rapid mass loss on the main sequence. It then summarizes the author's investigation of a model for mass loss where photospheric acoustic waves control the flow rate.