Detectors human observer

Since color matching is meant for humans, it is natural to define color in terms of an average, or "Standard Observer". Our first step is to build an instrument which contains three colored lamp sources, a place for the individual observer, intensity detectors, and a monochromator, as shown in 7.8.19. on the next page. 

Flow-injection analysis is a versatile technique to evaluate the performance of a detector system. CHEMFETs may have an advantage over ISEs because of their small size and fast response times. We have tested our K+-sensitive CHEMFETs in a wall-jet cell with a platinum (pseudo-)reference electrode. One CHEMFET was contineously exposed to 0.1 M NaCl and the other to a carrier stream of 0.1 M NaCl in which various KC1 concentrations in 0.1 M NaCl were injected. The linear response of 56 mV per decade was observed for concentrations of KC1 above 5 x 10"5 M (Figure 9). When we used this FIA cell (Figure 10) for determination of K+ activities in human serum and urine samples, excellent correlations between our results and activities determined by flame photometry were obtained (Figure 11). 

Interfacing the TEA to both a gas and a HPLC has been shown to be selective to nitro-based explosives (NG, PETN, EGDN, 2,4-DNT, TNT, RDX and HMX) determined in real world samples, such as pieces of explosives, post-blast debris, post-blast air samples, hand swabs and human blood, at picogram level sensitivity [14], The minimum detectable amount for most explosives reported was 4-5 pg injected into column. A pyrolyser temperature of 550°C for HPLC-TEA and 900°C for GC/TEA was selected. As the authors pointed out, GC uses differences in vapour pressure and solubility in the liquid phase of the column to separate compounds, whereas in HPLC polarity, physical size and shape characteristics determine the chromatographic selectivity. So, the authors reported that the use of parallel HPLC-TEA and GC-TEA techniques provides a novel self-confirmatory capability, and because of the selectivity of the technique, there was no need for sample clean-up before analysis. The detector proved to be linear over six orders of magnitude. In the determination of explosives dissolved in acetone and diluted in methanol to obtain a 10-ppm (weight/volume) solution, the authors reported that no extraneous peaks were observed even when the samples were not previously cleaned up. Neither were they observed in the analysis of post-blast debris. Controlled experiments with handswabs spiked with known amounts of explosives indicated a lower detection limit of about 10 pg injected into column. 

Visual Observation. Because the human eye is a very sensitive detector with a wide range of spectral recognition, qualitative fluorescent thin-layer methods in the chnical laboratory use short- and long-wavelength ultraviolet lamp source coupled with visual observation. 

One of the most commonly used type of broadband detectors for measurement of solar UVR, the so-called Robertson-Berger type detector [12,13], has a spectral sensitivity which is adapted to the standardized erythema action spectrum of the human skin [14]. It has the maximum of its sensitivity around 297 nm, then sensitivity decreases steeply to about 320 nm and in the UV-A range the sensitivity is about 1000 times smaller than at the maximum in the UV-B. Thus these detectors give a direct measure for the biologically relevant irradiance. However, as no one available detector has a spectral sensitivity perfectly matched with the erythema action spectrum, corrections are necessary to get a standardized output from these instruments. These corrections depend on the variation of the solar spectrum, mainly correlated with solar zenith angle and with total atmospheric ozone content, and are specific to an individual instrument. This conversion from detector based units into absolutely defined erythemally weighted units may not be necessary if relative variations of UVR are observed over longer time scales at one station only and no absolute comparison is made with results from other detectors. 

Ernest Marsden stndied at the University of Manchester under Ernest Rutherford and Eians Geiger. Although a physicist, he would help elucidate something of value to all chemists the internal structure of the atom. This was accomplished by observing the path of a-particles in Rutherford s famous gold foil experiment, in which it was really the human eye, pressed to a short-focus telescope for hours on end in a thoroughly darkened room, that was the detector. 

The earliest detector used for visible light spectroscopy was the human eye. There are still spectroscopes and color comparators designed for visual observation of color and intensity. 

It has been observed that the discriminatory capabilities of human olfaction are tremendous It was estimated that an untrained person could differentiate up to ten million odors, perhaps even significantly more than that. Information theory then shows that in order to encode the qualities of ten million odors in a simple binary mode (Monoosmatic components on or off, their intensity, albeit important, is in this connection disregarded) only 2h to 27 specific profiles, disregarding possible and probable redundancies, and therefore the same number of complementary receptor sites would be required. Assuming furthermore that said redundancy, in which the informational modalities of two different specific receptor sites of two different olfactory neurons are confluent in one collector cell and therefore contribute to the expression of only one monoosmatic component is indeed operational it becomes necessary to increase the total number of types of specific receptor sites to 2k-30. This means that only 2U-30 specific detector proteins are required for structure recognition in the transduction process. This compares to about UOOO enzyme systems in different stages of activity estimated to be present in a cell any time. 

Detection, in this context, refers to the entire observation part (detection, recognition, identification and classification) of the reconnaissance process. Detection immediately implies that some kind of sensor is observing a scene. Sensors (or detectors) could be broadly grouped as human senses, optical sensors, electro-optical sensors and a group labelled other (Fig. 5.5). We shall focus on optical sensors, while the forrrth group of sensors, labelled other , will not be discrrssed here. All of these sensors provide information to the hitman s senses, in order to enhance the human s situational awareness. 

Some effort has also been focused on the determination of other isotope ratios, particularly St/ St with TOF-ICP-MS and LA-TOF-ICP-MS [104].These efforts have not, however, yielded precision and accuracy useful for the characterization of human tooth enamel for population movement studies. Part of the problem probably arises from interferences produced by the calcium phosphate matrix [106], but there also appears to be TOF detector-related fractionation akin to but more extreme than that observed for Pb/ Pb. 

Local features describe the observations as a collection of local patches, which can be samples, either densely spaced or at space-time interest points. Superior to global features, local features do not require accurate localization and background subtraction. The first type of local features is space-time interest point detectors, which are the locations in space and time where sudden changes in movement occur in the video. The locations are viewed as the most informative source for human activity recognition. Researches that use space-time interest points include those by Laptev and Lindeberg [5] and Harris and Stephens [6]. The main limitation of using these features is that the number of stable interest points is normally small. Fortunately, this limitation has been partially addressed by Dollar et al. [7] and Chomat et al. [8]. 

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