Data dredging

Failure to adequately define end-points prospectively, and retrospective data dredging ... 

Data mining does not equal data dredging. It is a systematic screening for drug-event combinations that are being reported disproportionately. It is essentially a quantitative signal detection method. 

Monitoring for safety presents statistically difficult problems. In looking for safety signals, the DMC searches for the unknown, the rare unexpected event. Problems of multiplicity abound—many outcomes and many looks conspire to muddle the sample space and therefore make probabilities ill defined. While one can, and should, specify precisely the number of outcomes to evaluate for efficacy, by definition one carmot specify the number of hypotheses relevant to safety. Instead, the DMC must remain alert to react to surprises, turning a fundamentally hypothesis-generating ("data dredging") exercise into somewhat of a hypothesis-testing framework. 

Preliminary laboratory data demonstrate the feasibility of removing Pb, Cr, Cd, Ni, Cu, Zn, As, TCE, BTEX compounds, and phenol from soils (clays and sandy clayey deposits, and dredged sediments) using EO technology. It has been demonstrated that 75 to 95% of Pb can be removed across the cell, in which a significant amount of the removed Pb can be electroplated at the cathode. 

Bay, Massachusetts. Gas liquid chromatography was used to detect hydrocarbons present at different depths in the sediment, while low resolution mass spectrometry was employed to measure concentrations of paraffins, cycloparaffins, aromatics and polynuclear aromatics. Their data show that the concentrations of total and saturated hydrocarbons decreased with increased depth, and it was noted that identification and quantification of hydrocarbons in oil-contaminated sediments is required if the fate of these compounds in dredge spills is to be determined. 

Ocean Data Evaluation System (ODES) Data Submissions Manual QA/QC Guidance for Sampling and Analysis of Sediments Water and Tissue for Dredged Material Evaluations Chemical Evaluations Quality Assurance Plan for the National Pesticide Survey of Drinking Water Wells Analytical Method 2, Chlorinated Pesticides Quality Assurance Project Plan for Analytical Control and Assessment Activities in the National Study of Chemical Residues in Lake Fish Tissue... 

The sediment from Amerikahaven (site 10) was found to contain unexpectedly low contaminant levels during sampling in 1996 (see also De Boer et al., 2001). This was attributed to repeated dredging activity. The sediment was therefore sampled a second time in September 1997 at a non-dredged site. Analysis of this sediment showed considerably higher contaminant levels. These results are considered more representative of this location and were therefore used instead of the 1996 data in the multivariate statistical analysis of biomarker data. Sediment bioassays were however conducted with the material collected in 1996 and these data for location no. 10 were used for multivariate analysis when sediment chemistry was included. 

The in vitro bioassay for dioxins with cleaned sediment extracts (DR-CALUX) proved to comply with the QA/QC criteria needed to guarantee the reliability of data in an inter- and intralaboratory study (Besselink et al., 2004). The chemical stability of dioxins makes it possible to apply destructive clean-up procedures which remove all matrix factors. Sample extraction and cleanup for other in vitro bioassays for specific mechanisms of toxicity require further development to make sure that the chemicals of interest are not lost or unwanted chemicals included in the sediment extract to be tested. Table 4 summarizes possible bioassays that could be performed in addition to chemical analyses with the dredged sediment in a licensing system. 

Varacin (114), a cytotoxic compound closely related to lissoclinotoxin A (106), was isolated from a Fijian sample of L vareau and a benzopentathiepin structure was proposed on the basis of spectral data [131]. Two total syntheses of varacin (114) have been carried out [132,133] and later, further syntheses were described [134-135]. N,N-dimethyl-5-(methylthio)varacin (115) and the corresponding trithiane (116) were obtained from L. japonicum from Palau and 3,4-desmethylvaracin (117) was isolated from a Eudistoma sp. from Pohnpei [136], An inseparable mixture of 5-(methylthio)varacin (118) and the corresponding trithiane (119) was obtained from a Pohnpeian Lissoclinum sp. [136]. Three additional antimicrobial polysulfides of the varacin family (120-122) were isolated from Polycitor sp., collected by dredging in the Sea of Japan [137]. 

Many fundamental problems remain to be solved, and much of the basic abundance data required to guide us are still missing. Some important problems yet before include a) the question of internal mixing on the main sequence to account for the abundance changes seen in the first dredge-up. This problem may have application to the question of the lithium rich giants and the weak G-band stars as well, b) The origin of the early R stars. If they do arise from a violent helium-core flash, we... 

The pT-method can also be applied to assess liquids (untreated and treated wastewater, surface waters and groundwater). All data from aquatic toxicity tests used to detect pollutants can be integrated into this method. A general description of the pT-method is given in Chapter 3 of this volume. The present chapter specifically addresses the application of the pT-method to sediments and dredged material in order to classify and categorize the hazard associated with the degree of contamination of these matrices. 

In all cases, results of ecotoxicological and chemical analytical data are ranked equally. Generally, the most environmentally-conservative response will serve as the yardstick to assign a sediment sample to a management category for dredged-material relocation (Schubert et al., 2000). 

Petrological and geochemical data are available for a few dredged samples from some seamounts. Rock compositions range from tholeiitic basalt to alkali basalt, hawaiite and basanite (Calanchi et al. 1989 and references therein Fig. 8.16). Tholeiites have been found at Tetide volcano. These rocks are sparsely porphyritic, with phenociysts of orthopyroxene rimmed... 

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