A cultura da mandioquinha-salsa e sua relação com os fungos micorrízicos.

A cultura da mandioquinha-salsa. Benefícios dos fungos micorrízicos arbusculares. Interações solo - micorrizas arbusculares. Possibilidade de relações entre a mandioquinha-salsa e os fungos micorrízicos arbusculares.bitstream/CNPAB-2010/32101/1/doc180.pd

Critical points on growth curves in autoregressive and mixed models

Adjusting autoregressive and mixed models to growth data fits discontinuous functions, which makes it difficult to determine critical points. In this study we propose a new approach to determine the critical stability point of cattle growth using a first-order autoregressive model and a mixed model with random asymptote, using the deterministic portion of the models. Three functions were compared: logistic, Gompertz, and Richards. The Richards autoregressive model yielded the best fit, but the critical growth values were adjusted very early, and for this purpose the Gompertz model was more appropriate

Cops, Teachers, and the Art of the Impossible: Explaining the lack of diffusion of impossible job innovations

In their now classic Impossible Jobs in Public Management, Hargrove and Glidewell (1990) argue that public agencies with limited legitimacy, high conflict, low professional authority, and weak agency myths have essentially impossible jobs. Leaders of such agencies can do little more than cope, which is also a theme of James Q. Wilson (1989), among others. Yet in the years since publication of Impossible Jobs, one such position, that of police commissioner has proven possible. Over a sustained 17-year period, the New York City Police Department has achieved dramatic reductions in crime with relatively few political repercussions, as described by Kelling and Sousa (2001). A second impossible job discussed by Wilson and also by Frederick Hess (1999), city school superintendent, has also proven possible, with Houston and Edmonton having considerable academic success educating disadvantaged children. In addition, Atlanta and Pittsburgh enjoyed significant success in elementary schooling, though the gains were short-lived for reasons we will describe. More recently, under Michelle Rhee, Washington D.C. schools have made the most dramatic gains among city school systems. These successes in urban crime control and public schooling have not been widely copied. Accordingly, we argue that the real conundrum of impossible jobs is why agency leaders fail to copy successful innovations. Building on the work of Teodoro (2009), we will discuss how the relative illegitimacy of clients and inflexibility of personnel systems combine with the professional norms, job mobility and progressive ambition of agency leaders to limit the diffusion of innovations in law enforcement and schooling. We will conclude with ideas about how to overcome these barriers

Habitat-Specific Morphological Variation among Threespine Sticklebacks (Gasterosteus aculeatus) within a Drainage Basin

Habitat-specific morphological variation, often corresponding to resource specialization, is well documented in freshwater fishes. In this study we used landmark based morphometric analyses to investigate morphological variation among threespine sticklebacks (Gasterosteus aculeatus L.) from four interconnected habitat types within a single lowland drainage basin in eastern England. These included the upper and lower reaches of the river, the estuary, a connected ditch network and a coastal salt marsh. We found significant habitat-specific differences in morphology, with three axes of variation describing differences in orbit diameter, body depth, caudal peduncle shape and pectoral fin positioning as well as variation in relative dorsal and pelvic spine size. Interestingly, the ditch system, an artificial and heavily managed habitat, is populated by sticklebacks with a characteristic morphology, suggesting that human management of habitats can in some circumstances lead to morphological variation among the animals that inhabit them. We discuss the mechanisms that conceivably underlie the observed morphological variation and the further work necessary to identify them. Finally, we consider the implications of habitat-specific body shape variation for the behavioural ecology of this ecologically generalist species