Life table invasion models: spatial progression and species-specific partitioning

Biological invasions are increasingly being considered important spatial processes that drive global changes, threatening biodiversity, regional economies, and ecosystem functions. A unifying conceptual model of the invasion dynamics could serve as a useful tool for comparison and classification of invasion processes involving different species across large geographic ranges. By dividing these geographic ranges that are subject to invasions into discrete spatial units, we here conceptualize the invasion process as the transition from pristine to invaded spatial units. We use California cities as the spatial units and a long-term database of invasive tropical tephritids to characterize the invasion patterns. A new life-table method based on insect demography, including the progression model of invasion stage transition and the species-specific partitioning model of multispecies invasions, was developed to analyze the invasion patterns. The progression model allows us to estimate the probability and rate of transition for individual cities from pristine to infested stages and subsequently differentiate the first year of detection from detection recurrences. Importantly, we show that the interval of invasive tephritid recurrence in a city declines with increasing invasion stages of the city. The species-specific partitioning model revealed profound differences in invasion outcome depending on which tephritid species was first detected (and then locally eradicated) in the early stage of invasion. Taken together, we discuss how these two life-table invasion models can cast new light on existing invasion concepts; in particular, on formulating invasion dynamics as the state transition of cities and partitioning species-specific roles during multispecies invasions. These models provide a new set of tools for predicting the spatiotemporal progression of invasion and providing early warnings of recurrent invasions for efficient management

Ultrasonographic features of peritoneal cestodiasis caused by Mesocestoides sp. in a dog and in a cat

Peritoneal infections caused by Mesocestoides spp. are rare in dogs and cats. Little data exist on the role of abdominal ultrasonography for diagnosis and therapy management of the disease. We describe the ultrasonographic features of peritoneal cestodiasis in a dog and in a cat. In the dog, abdominal ultrasound allowed both a presumptive diagnosis and the collection of tissue samples to confirm peritoneal larval infection. Utrasound was also very useful for therapy management. In the second patient the ultrasonographic features of tetrathyridial infection in a cat in which the parasite was observed as an incidental finding during ovariohysterectomy are described

New results from a search for v(mu) -> v(tau) and v(e) -> v(tau) oscillation

A first analysis of the complete set of data collected by CHORUS in the years 1994-1997 is presented. The search for nu (tau) charged current events has been performed for both leptonic and hadronic decays of the tau lepton. No tau candidate has been found, A nu (tau) --> nu (tau) mixing is excluded down to sin(2)2 theta (mu tau) = 6.8 x 10(-4) for large Deltam(2) (90% C.L.)