Viscerotropic velogenic Newcastle disease in turkeys: immune response following vaccination with either viable B1 strain or inactivated vaccine.
When used as a vaccine, live letogenic B1 Newcastle disease virus (NDV) protects turkeys against challenge-exposure to viscerotropic velogenic NDV (VVNDV). Low-level passively-immune poults were vaccinated one, two, or three times at various intervals and their immunity challenged at various times from 1 to 10 months of age. Newcastle disease virus was isolated readily from either the blood, trachea, or vent of turkeys in all challenge groups (through 5 months of age) on the 3rd to 6th days postchallenge (PC) but after 14 days PC was isolated rarely. Virus was isolated from turkeys that had high titers of serum hemagglutination-inhibition antibodies at the time of challenge. The anamnestic antibody response appeared to be stronger in poults that had low antibody titers prior to challenge-exposure to VVNDV. In a small-scale study with an inactivated VVNDV vaccine, vaccinated poults were protected against challenge with the homologous viscerotropic virus. Parallel control studies on the infectivity of viscerotropic NDV for turkeys indicated that resistance to VVNDV increased with age.
Viscerotropic velogenic Newcastle disease in turkeys: vaccination against loss of egg production.
Live B1 Newcastle disease virus was administered to young turkeys either intraocularly or by driniking water, or by both methods. Protection against egg production loss was evaluated by challenge-exposure to viscerotropic velogenic Newcastle disease virus in drinking water. During 22 days postchallenge (PC), none of the vaccinated hens had morbidity, whereas 44% of the unvaccinated controls died 6-13 days PC. Percent egg production (PEP) of all groups 1-5 and 6-22 days PC were compared with their levels 1-5 days before challenge. For days 1-5 PC, changes were not significant. For days 6-22 PC, changes for all groups were siginficant lower. The controls had 0 production. Hens vaccinated only at 4 days or at 4 days and again at 4 weeks averaged one-third or less of prechallenge levels but were recovering. Those revaccinated at 4 months maintained 84-91% of their prechallenge levels and were considered satisfactory. Broodiness was a detracting factor in one group of hens vaccinated at 4 days, 4 weeks, and 51/2 months. They averaged two-thirds of prechallenge levels but were in decline.
Law as Palimpsest: Conceptualizing Contingency in Judicial Opinions (forthcoming 2009)
Metaphors create conceptualizations, and for decades legal academics have employed metaphors to shape understandings of legal problems. But no metaphor in current use successfully conceptualizes the contingency of judicial opinions and the complexity of the relationship between opinions and precedent. This Article seeks to fill this void by introducing a new metaphor, the palimpsest, into the realm of legal analysis. A palimpsest is a writing surface that can be cleared away for reuse, like a personal blackboard. What distinguishes a palimpsest from other writing surfaces is that its removed contents do not disappear, but remain, obscured yet recoverable: A writing on a palimpsest never goes away. This Article argues that thinking of judicial opinions as being part of a shared, ever-evolving palimpsest underscores the fact that they are ultimately contingent and serves as a reminder of the multiple levels of interconnectedness between them and the cases they cite. Precedents—like the underlayers of a palimpsest—never go away, and they inform and shape the application of opinions in ways far more significant than simply serving as points of reference. A palimpsestic approach to understanding judicial decisionmaking also helps to explain why even the oldest, most reviled cases remain part of our national psyche—like underlayers of a palimpsest, they can never truly disappear, and their continued presence forces us to grapple with their existence. Finally, considering judicial opinions as part of a shared palimpsest reminds us that even the most troubling opinion is ultimately contingent, its application subject to reexamination and revision by future courts and future generations. Just as such an opinion replaces its precedents, it too will one day be replaced, like each of a palimpsest’s layers. 2 Law as Palimpsest [Vol. __:__ Law as Palimpsest: Conceptualizing Contingency in Judicial Opinions