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In late February 2008, law enforcement officials in Las Vegas, Nevada, discovered in a hotel room, a copy of The Anarchist Cookbook, suspected castor beans and a "white powder" thought to be a preparation of ricin. Ricin is a deadly toxin from the seed of the castor bean plant (Ricinus communis). The United States regulates the possession, use, and transfer of ricin and it is the only substance considered a warfare agent in both the Chemical and the Biological Weapons Conventions. Six samples obtained from the hotel room were analyzed by laboratories at the Centers for Disease Control and Prevention using a panel of biological and mass spectrometric assays. The biological assays (real time-PCR, time resolved fluorescence and cytotoxicity) provided presumptive evidence of active ricin in each of the samples. This initial screen was followed by an in-depth analysis using a novel, state-of-the-art mass spectrometry-based ricin functional assay and high sensitivity tandem mass spectrometry for protein identification. Mass spectrometric analysis positively identified ricin and confirmed that in each of the samples it was enzymatically active. The tandem mass spectrometry analysis used here is the most selective method available to detect ricin toxin. In each sample, ricin was unequivocally identified along with other R. communis plant proteins, including the highly homologous protein RCA120. Although database searches using tandem mass spectra acquired from the samples indicated that additional controlled substances were not present in these samples, the mass spectrometric results did provide extensive detail about the sample contents. To the best of our knowledge following a review of the available literature, this report describes the most detailed analysis of a white powder for a public health or forensic investigation involving ricin.  相似文献   
864.
Parenting plan evaluators are expert witnesses who offer their opinion. Courts in common law jurisdictions generally do not accept evidence of an opinion as it is not considered to be reliable evidence from which to establish a fact. An exception to that general principle is expert opinion evidence. In short, an opinion from a person with specialized knowledge or expertise about the area in which they are an expert may be sufficiently reliable to form an evidentiary basis from which to make a finding of fact, provided the opinion meets certain criteria. These criteria will be discussed in this article, as well as what is relevant, reliable and persuasive evidence. The relevant legal principles will be examined in an historical and contemporary, theoretical and practical context. The authors reflect on their considerable experience as consumers of expert evidence and apply this to parenting plan evaluations, as well as considering future challenges in the field.  相似文献   
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