8 research outputs found

    Mixed infections with cucumber necrosis virus and tobacco necrosis virus

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    Tobacco necrosis virus (TNV) interfered with cucumber necrosis virus (CNV) replication in mixed infections. TNV inhibited both the initiation of CNV infections and subsequent CNV multiplication. Evidence of interference was found in qualitative evaluations of symptoms on a wide host range and by quantitative evaluations (lesion counts and incidence of systemic symptoms) on cucumber, cowpea, and bean. Fresh weight measurements similarly indicated antagonism in mixed infections. Some evidence of CNV interfering with TNV replication was found, in the form of a reduction in the occurrence of systemic symptoms. Photometric scanning of sucrose density gradient columns after centrifugation revealed that in mixed infections CNV reached only half the concentration attained in single infections while TNV was unaffected or even very slightly increased in concentration. This interference continued even when high temperatures greatly limited TNV replication. Only at 3¬į C, where its replication was barely detectable, did TNV have no effect on the CNV concentration attained. CNV did not significantly aid TNV replication at any temperature. In serial passage of mixed infections TNV quickly gained in concentration relative to CNV. Although CNV and TNV symptoms could not readily be distinguished from one another on most hosts, Phaseolus vulgaris var. Topcrop kept at 23 C and Chenopodium capitaturn kept at 18 C were established as reliable indicators of CNV and TNV respectively. One preparation from doubly infected tissue showed evidence of possible phenotypic mixing based on polyacrylamide gel electrophoresis and on reactions with antisera, although this could not be confirmed by infectivity tests. Through use of the antigen-antibody neutralization test, another virus preparation from doubly infected tissue gave evidence of possible genomic masking of TNV RNA in CNV coat protein. No evidence of possible genomic masking in the opposite direction was found.Land and Food Systems, Faculty ofGraduat

    The Effect of Work First Job Placements on the Distribution of Earnings: An Instrumental Variable Quantile Regression Approach

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    Federal and state employment programs for low-skilled workers typically emphasize rapid placement of participants into jobs and often place a large fraction of participants into temporary-help agency jobs. Using unique administrative data from Detroit\u27s welfare-to-work program, we apply the Chernozhukov-Hansen instrumental variables quantile regression (IVQR) method to estimate the causal effects of welfare-to-work job placements on the distribution of participants\u27 earnings. We find that neither direct-hire nor temporary-help job placements significantly affect the lower tail of the earnings distribution. Direct-hire placements, however, substantially raise the upper tail, yielding sizable earnings increases for more than fifty percent of participants over the medium-term (one to two years following placement). Conversely, temporary-help placements have zero or negative earnings impacts at all quantiles, and these effects are economically large and significant at higher quantiles. In net, we find that the widespread practice of placing disadvantaged workers into temporary-help jobs is an ineffective tool for improving earnings and, moreover, that programs focused solely on job placement fail to improve earnings among those who are hardest to serve. Methodologically, one surprising result is that a reduced-form quantile IV approach, akin to two-step instrumental variables, produces near-identical point estimates to the structural IVQR approach, which is based on much stronger assumptions

    Differentiating, Collaborating, Outdoing: Nordic Identity and Marginality in the Contemporary World

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    World Federation of Societies of Biological Psychiatry (WFSBP) Guidelines for Biological Treatment of Schizophrenia, Part 2: Long-term treatment of schizophrenia

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    Abstracts of papers and posters advanced activities in pharmaceutical care 24th European Symposium on Clinical Pharmacy

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