Exposure time, data collection

All data recorded in the data base have been acquired from plant records. Statistical reductions of data for generation of reports or specific end use are available. Data are currently collected from four operating plants (eight units). Time clocks have been installed on components, to record actual exposure time. Event data are available on a broad variety of safety and commercial grade components including pumps, valves, transformers, diesels, filters, tanks (vessels), and heat exchangers. 

The parameters of this category should be recorded automatically using monitor channels of the data acquisition system (cf. Sect. 4.3). The value of the experiment is strongly resting on these data. In case of a malfunction or unavailability of the monitor channel module of the data acquisition system at least the most important parameter must be collected using paper and pencil. These parameters are the main process parameter6, the exposure times, and the readings of the ionization chambers. 

Even in the nominal absence of laser fluctuations or other imagedegrading aberrations, the number of photons that hit the detector during the data collection period of the image (i.e., the exposure time for a CCD image or the pixel dwell time for a confocal image) will contain considerable noise. The photon count x follows a Poisson distribution (Fig. 7.7A) with mean value fi as... 

Time-Resolved Crystallography. Time-resolved crystallography (TC) uses an intense synchrotron X-ray source and Laue data collection techniques to greatly reduce crystallographic exposure times. Normal time resolution for X-ray... 

Fig. 9 Epifluorescence microscopy images of the amyloid fibrils of PrP 90-231 (1 pM), stained at room temperature with (a) ThT alone (10 pM) (exposure time 1.6 s), and (b) with preformed ThT-Ag clusters (exposure time 0.02 s). ThT-Ag clusters were preformed by irradiation of aqueous solutions of ThT (10 pM)/AgN03 (1 pM) at 312 nm for 3 min. Scale bars = 10 pm. (c) Photobleaching kinetics of the fibrils stained with ThT (black line) vs. photoactivation kinetics of the fibrils stained with ThT-Ag clusters (red line). Data collected from a 5 pm x 5 pm area and normalized to the intensity measured at zero time [31 ]...

When the project was started in 2002, European exposure factor data were scattered within numerous national and international institutions. ExpoFacts has created no new data, but instead compiled the existing data into one Internet database, where it can be easily found, screened, and downloaded from. Data were collected from the EU countries, candidate countries to EU, and EFTA countries. As a result, the ExpoFacts database contains data from 30 European countries. In addition to the population time use patterns and exposure route information, e.g., dietary statistics, the database contains socio-demographic and physiologic information to enable database use as a tool for population-wide exposure modeling and risk assessment. 

Further reductions in exposure time and hence radiation damage in virus crystallography may accrue from the use of white beam (modified) Laue methods preliminary work on this is in progress (Bloomer and Helliwell (1985), unpublished at the SRS and Rossmann et al. at Cornell unpublished (1986)). Data collection on some virus crystals is virtually impossible in the home laboratory. 

It took the short time of one year or so to solve the structure of rhinovirus which causes the common cold. This relied on two major advances in methods. The first was the use of synchrotron radiation in data collection. Nearly a million reflections were collected on the protein crystallography facility at the Cornell Synchrotron source in a matter of days. This conveyed a speed advantage over data collection on a conventional source and also ameliorated an otherwise impossible problem of radiation damage when long exposure times were used. The far greater rate of radiation damage in the X-ray beam in relation to plant viruses is symptomatic of an inherently less stable protein capsid and the absence of quasi-symmetry. The capsid consists of 60 copies each of four proteins and the virus with about 30 % RNA has a total molecular weight of about 8.5 million. 

As mentioned in sections 1.2.2.2 and 1.2.3.2, the photochromic reactions of spirobenzopyran and spironaphthoxazines show a marked solvent dependency and this is also the case with benzo and naphthopyrans. Consequently, spectral data collected from the literature is only comparable within any one study or where the same solvent has been used. This accounts for any discrepancies between one set of results and any other one listed in this and related sections of this chapter. The data normally quoted when discussing the properties of photochromic materials relate to the absorption maximum (2. ) of the coloured state, the change in optical density (absorbance) on exposure to the xenon light source (AOD) and the fade rate which is the time in seconds for the AOD to return to half of its equilibrium value. 

Fig. 7 Diffraction profile collected from Te-III at 8.5 GPa. The data were collected on beamline 9.1 at the SRS synchrotron, with an exposure time of 23 min. The tick marks beneath the profile identify those reflections that are explained by the body-centred monoclinic unit cell...

Takada, et. al. (7), compared the 3M Organic Vapor Monitor to charcoal tubes by studying the weight of contaminant collected as a function of (1) exposure time at various concentrations and (2) chamber concentration at various exposure times. Their data is summarized in Figures 1,2,3,4. Their study led to the following major conclusions ... 

Figure 10 represents the total corrected mass as a function of exposure dose for toluene from the data collected in Figure 6. A linear relationship exists out to exposure dose levels of at least 9,000 ppm-hours versus 4,000 ppm-hours for the front section of the badge. This extended linearity allows one to increase the sampling time for measuring an exposure.

Time-resolved x-ray crystallography (TC) is a more recent advanced application of x-ray crystallography. It uses an intense synchrotron x-ray source and data collection methods to reduce crystallographic exposure times. This allows multiple exposures to be taken over time at near-physiological, crystalline conditions to determine the structures of intermediates. A typical problem with this method is that the existence of the intermediates is brief, resulting in difficulty in interpreting the resulting electron density maps. 

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