Species abundance distributions: moving beyond single prediction theories to integration within an ecological framework

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75247/1/j.1461-0248.2007.01094.x.pd

Quantitative Risk Assessment for Zoonotic Transmission of Cryptosporidium parvum Infection Attributable to Recreational Use of Farmland

Cryptosporidiosis caused by Cryptosporidium parvum infection is a major cause of enteric illness in man and there is a significant reservoir in animals, particularly young ruminant species. To preliminary assess the magnitude of the risk posed by contact with faeces produced by infected livestock, two microbiological risk assessments have been developed: one for the risk of human infection with C. parvum while camping on contaminated land recently grazed by infected suckler cattle and a comparable risk assessment for camping on land recently spread with contaminated cattle slurry. Using a worst-case scenario approach, the upper level of risk was estimated to be one infection in every 6211 person-visits for a camping event on land recently grazed by infected cattle. Translated into camping events of 100 persons, this risk estimate would most likely lead to zero (98% likelihood) or one infection (1% likelihood). The results for cattle slurry model are similar despite different pathways. Sensitivity analysis was conducted for the grazing cattle model only. This suggested that the time between grazing and camping was the most important control strategy, but increasing hand-washing frequency and the removal of cattle faeces before camping would also be beneficial. If the upper level of risk were to be judged unacceptable then further data would be required to more accurately estimate the risk of infection through these scenarios. Further research would also be required to assess the fraction of cases attributable to camping and/or environmental contact with Cryptosporidium oocysts

A checklist for ecological management of landscapes for conservation

The management of landscapes for biological conservation and ecologically sustainable natural resource use are crucial global issues. Research for over two decades has resulted in a large literature, yet there is little consensus on the applicability or even the existence of general principles or broad considerations that could guide landscape conservation. We assess six major themes in the ecology and conservation of landscapes. We identify 13 important issues that need to be considered in developing approaches to landscape conservation. They include recognizing the importance of landscape mosaics (including the integration of terrestrial and aquatic areas), recognizing interactions between vegetation cover and vegetation configuration, using an appropriate landscape conceptual model, maintaining the capacity to recover from disturbance and managing landscapes in an adaptive framework. These considerations are influenced by landscape context, species assemblages and management goals and do not translate directly into on-the-ground management guidelines but they should be recognized by researchers and resource managers when developing guidelines for specific cases. Two crucial overarching issues are: (i) a clearly articulated vision for landscape conservation and (ii) quantifiable objectives that offer unambiguous signposts for measuring progress

Casting Metals in Dentistry: Past - Present - Future

This article deals mainly with the development of dental casting techniques and formulation of the different groups of alloys used in the fabrication of ceramo-metal restorations. It is recognized that in order for the quality of dental cast restorations to be improved, having alloys with the proper composition is not enough. Biocompatibility, good mechanical and physical properties, longevity of the restoration, compatibility with porcelain, and a simple manipulative technique are as important. Researchers have contributed to different aspects of dental castings and have made cast restorations what they are today. Unfortunately, much of the original basic research has been overlooked by present investigators, who have duplicated studies conducted in the past without realizing that the study had already been performed and the research had been published. The main reason for this is that abstracts of articles published prior to 1975 are not available through a library computer-search system. To obtain copies of articles published prior to 1975, one has to search the literature to know where they were published. This article provides references for much of the past work in this area. Also, dental libraries do not carry copies of U.S. patents. This places the majority of researchers located at dental schools at a disadvantage. They are not familiar with what the patents claim, what is taught, and why certain elements are added or eliminated from alloys and investment materials. This article also provides the numbers of many U.S. patents. By having the patent number, one can obtain the text of the patent from the U.S. Patent Office in Washington, DC. Since esthetics plays an important role in today's society, emphasis will be given only to alloys designed for fabrication of ceramo-metal restorations. Many ceramo-metal alloys are available today, and they are classified differently by different individuals. In this article, classification will be based on the major components of these alloys, as well as on a chronological introduction of one group leading to the development of the next group. Based on this, one can classify these alloys into six major groups. Chemical composition, properties, and the developers of these alloys, along with their U.S. patents, are given. Recently, two types of all-ceramic restorations have been introduced. The main advantage of the all-ceramic restoration is its superior esthetic quality compared with that of ceramo-metal restorations. Their main disadvantages are low strength and ductility. Their strength, however, is sufficient for single-unit restorations, but not for bridgework. The use of titanium for dental restorations has also been studied, and it has been found to be suitable. Future Studies - Future work should be devoted to the following: (1) the development of stronger and more ductile ceramic materials: (2) further study of the promising palladium alloys from the noble metal group and titanium alloys from the base metal group; (3) the development of easier and less-time-consuming techniques for the fabrication of dental appliances; (4) the development of a powder technique rather than a cast technique for future fabrication methods; and (5) the development of new laboratory equipment, e.g., a single sintering oven capable of sintering both ceramic and metallic particles, which would be accepted if the powder technique is developed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67759/2/10.1177_08959374880020011701.pd