Site study

ECASS-II was designed to test a lower dose of rt-PA (0.9 mg/kg) during the same 0-6-hours time period after stroke onset, using similar inclusion criteria as in ECASS-I. ° The primary endpoint was the proportion with a favorable outcome on the mRS scale (defined as a score of 0 or 1). There was no difference in this outcome between rt-PA-treated and placebo controls (40% vs. 37%, p = 0.28). A separate analysis of the 158 subjects enrolled within 3 hours of stroke onset also showed no difference in the proportion with a favorable outcome (42% vs. 38%, p = 0.63) this result, however, must be treated with caution because in ECASS-II there was a substantially lower number of patients treated within 3 hours of stroke onset, compared to the 1995 NINDS rt-PA study. Parenchymal hematoma on post-treatment CT was seen in 12% of rt-PA-treated and 3% of placebo patients (p < 0.001). The 90-day mortality rate was 11 % for the rt-PA group and 11 % for the placebo group (p = 0.54). Protocol violations were much less frequent in ECASS-II compared to ECASS-I (9% vs. 18%), probably because of standardized training in CT interpretation at the study sites. 

While clearly outlined criteria are essential, a lengthy list of exclusions can also impede subject recruitment. Therefore, a balance must be struck between what is scientifically desirable and that which is still practical with regard to the number of study sites and length of time required to complete the trial. 

The number of study sites to be used for a clinical trial depends on the characteristics and number of subjects that need to be recruited. Often, a sufficient number of participants cannot be enrolled from a single site, especially if the study inclusion criteria are restrictive and the timeframe for recruitment is limited. In order to complete the study within a reasonable period of time, an inclusion of multiple research centers is often necessary (Chow and Liu, 1998). The selection of study sites depends on several factors including ... 

The use of multiple study sites can facilitate enrollment and ensure diversity in the study sample. However, as the number of study sites increases, so too does the cost and complexity of managing the trial. Therefore, the proper balance must be struck between issues of cost, logistics, scientific considerations and practicality when deciding on the appropriate number of research sites. 

The study site, consisting of about 11 contaminated acres belonging to eight property owners, is in a small community midway between Verona and St. Louis, Missouri. Records indicate that on May 20, 1971, a truck driven by an employee of a salvage waste oil company was ticketed for being 950 pounds overweight. The truck was en route from Verona to St. Louis with a load of TCDD-contaminated still... 

Summary of ecosystem measurements that are routinely made at intensive watershed study sites... 

Results from the monitoring approach recommended by this book, particularly from intensively studied sites, offer the potential to further advance the development of models of mercnry cycling. The data from these sites can provide critical information... 

The guiding principles in test plot maintenance are to (1) minimize soil surface disturbance at all times, (2) ensure that control and treated plots are similarly maintained, (3) avoid applying other agrochemicals that may interfere with sample analysis or that are otherwise contrary to the purpose of the study, (4) follow the prescribed irrigation policy determined for the study site, and (5) keep bare-soil test plots free of vegetation, as follows. 

Protocols should require documentation of actual application practices and times. Samples of applied pesticides should be collected to document application rates to study sites. The test substance must be applied with typical equipment used for the crop, and the application must be made in accordance with the labeled use. Another variable that impacts such studies is the fact that most landowners have their own application equipment, which increases the variance in actual application rates among fields and may cause differential intra-field heterogeneity in application rates. 

Protocols must specify the number of study sites to be sampled for residues and the number of stations within a study site to be sampled. This is a difficult process to specify, but depends on traditional sampling theory. In general, the parameters that need to be evaluated for proper sampling design are the following ... 

The layout of a field study site needs to be established based on the study objectives. Typically, several lines of sample will be laid out in the downwind direction from the application area, perpendicular to the sprayer travel direction assuming a cross-wind normal to the application direction. Three or more parallel lines will provide useful information on spray deposition in the sampling area. If wind directions may be variable, these lines can be set up in various directions radiating outwards from the application area. 

Figure 2. HPLC chromatograms (isocratic mode, 60% methanol, 40% water) of sediment extracts from 15 study sites in west Florida coastal waters. Migration profile are compared among sediment extracts and crude extract of Nannochloris sp. cell-free culture [See Moon and co-workers (.26) for specific sites].

ItemDef OID="ID.siteid" SASFieldName="siteid" Name="Study Site Identifier" DataType="text" Length="10" /> tltemDef OID="ID.subjid" SASFieldName="subjid"... 

Sinclair, J.L. and Ghiorse, W.C., Distribution of protozoa in subsurface sediments of a pristine ground-water study site in Oklahoma, Appl. Environ. Microbiol., 53, 1157-1163, 1987. 

CASE STUDY SITE SELECTION FOR A 150,000,000 IJi/YR POLYSTYRENE PLANT USING THE SUSPENSION PROCESS... 

The climograph and altitude for each of the studied sites are shown in Figure 1. 

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