Detectable Color Change Research Articles

Mueller-Hinton broth undergoes visible oxidative color changes in the presence of peroxidase and hydrogen peroxide

In the presence of peroxidase and hydrogen peroxide, Mueller-Hinton broth undergoes a slow but clearly detectable color change from pale yellow to dark yellow or brown. An investigation of this phenomenon led to the conclusion that it is the result of the oxidation of tyrosine, a major component of the broth. Indeed, tyrosine has long been known to oxidize upon treatment with peroxidase and hydrogen peroxide. The observations reported here, besides being curious for the clinical microbiologist, might deserve attention for the possible implications in the medium color darkening which sometimes happens during microbial growth.

Stability of esmolol hydrochloride in the presence of aminophylline, bretylium tosylate, heparin sodium, and procainamide hydrochloride

The visual and chemical compatibility of esmolol hydrochloride mixed with aminophylline, heparin sodium, bretylium tosylate, or procainamide hydrochloride in 5% dextrose injection was studied. Esmolol hydrochloride 600 mg was injected into polyvinyl chloride bags containing 100 mL of 5% dextrose injection with aminophylline 100 mg, heparin sodium 5000 units, bretylium tosylate 100 mg, or procainamide hydrochloride 400 mg. All admixtures were prepared in triplicate and stored at room temperature under fluorescent light. Esmolol concentrations were measured with high-performance liquid chromatography at 0, 2, 4, 8, and 24 hours. Samples were also examined for precipitate formation and pH and color changes by using visual, microscopic, and spectrophotometric methods. No detectable changes in color or pH and no particulate formation were observed in any of the sample bags. Esmolol concentrations varied by less than 5% throughout the 24-hour study period. Esmolol hydrochloride was visually compatible and chemically stable for at least 24 hours when mixed with aminophylline, heparin sodium, bretylium tosylate, or procainamide hydrochloride in polyvinyl chloride bags containing 5% dextrose injection.

Monitoring sediment transport systems in a semiarid area using thematic mapper data

Thematic Mapper data, in the form of false color composites and change detection images, have been used to monitor and map four geomorphological process domains in southern Tunisia over a 4-year period. Hillslope, river channel, alluvial fan, and salt lake environments were examined using field surveys, laboratory analysis of sediment samples, and remotely sensed data. An assessment is made of the utility of Thematic Mapper data for geomorphological monitoring of these environments. The detection of large fluvial channels and circular ground water features (aioun) within one large playa have shown the value of using remotely sensed imagery for geomorphological mapping in such environments. As a result of this research it is shown that the traditional model of salt lake development based on the relative solubility of salts may need to be modified to take account of the influence of fluvial transport. Monitoring geomorphological changes in other process domains provided less satisfactory results; largely it is believed because of the almost complete absence of major rainfall events during the study period; however, geomorphological changes due to anthropogenic activity were successfully monitored.

Dry Matter Loss in Yellow Dent Corn Resulting from Invasion by Storage Fungi

Samples of high-temperature-dried yellow dent corn stored in the laboratory at moisture contents of 14.5-19.5% suffered increasing invasion by storage fungi, increasing loss in dry matter, and an increasing percentage of damaged (brown to black) germs with increasing moisture content and increasing time of storage. Invasion of the germs by storage fungi (especially Aspergillus glaucus) preceded any detectable weight loss and change in germ color. By the time the dry matter loss had reached 0.5-1.0% the germs of the corn kernels had been extensively invaded by storage fungi

On the colors of Jupiter's satellite Io: Irradiation of solid sulfur at 77 K

The colors of seven sulfur allotropes at 77 K have been investigated both before and after irradiation by a high‐pressure mercury lamp. S8 is white at 77 K but turns intense yellow within a few minutes on irradiation through quartz or DURAN. On warming, the yellow species (presumably chain‐like sulfur diradicals characterized by an absorption at 430 nm) decomposes near 260 K and polymeric sulfur (S∞) is formed; the sample color changes gradually to the very similar color of an S8–S∞ mixture, resulting in no visually detectable color change with temperature from 77 K to 260 K. This is consistent with the lack of posteclipse brightening on Io. Other sulfur forms also turn intense yellow (S7, S10), grayish yellow (S12, S20, S∞), or brownish yellow (S6) on irradiation at 77 K, and these colors also change to the normal colors of the starting materials on warming to 298 K. We suggest that the yellowish features on Io are caused by the effect of solar radiation on elemental sulfur. The yellow color thus produced may subsequently be modified by deposits of SO2 frosts and volcanic ash.

Induced desensitization

Viewing of annuli modulated in color in a sawtooth fashion in time results in differential threshold elevations for the detection of color changes of inscribed disks. The elevations are of nearly the same magnitude as those resulting from viewing modulated disks. However, the differential effects on thresholds for complimentary colors are reversed. The differential effects, thus, are correlated with the variation in appearance of the test area.

Higher order color mechanisms

Evidence supporting the existence of higher order color mechanisms, that is, ones beyond the previously identified second stage mechanisms is presented. This evidence includes a reanalysis of the data of Krauskopf et al. [ Vision Res. 20, 1123–1131 (1982)] on the desensitizing effects of viewing chromatically modulated fields, new experiments on a generalized version of the “transient tritanopia” experiment of Mollon and Polden [ Phil. Trans. R. Soc. Lond. 278, 207–240 (1977)] and results on the relationship between discrimination and detection of brief color changes.

Converging approaches in motion perception

While neuropsychological dissociations suggest that distinct processes are involved in execution or perception of transitive (object-related) and intransitive (non-object-related) actions, the few neuroimaging studies that directly contrasted the brain activations underlying transitive and intransitive gesture perception failed to find substantial differences between the two action types. However, the distinction could be visible on brain activity timing within the fronto-parietal network. In this study, we used Event-Related Potential (ERP) method to assess the temporal dynamics of object-related and non-object-related action processing. Although both meaningful, only object-related actions involve object motor features. Accordingly, perception of the two action types would show distinct neural correlates. Participants were presented with four movie types (ORA, Object-Related Action, NORA: Non-Object-Related Action and 2 control movies) and were instructed to perform tasks that required explicit or implicit action recognition (specific action recognition or color change detection). Movies were presented as Point-Light Display (PLD) and thus provided only information about gesture kinematics regardless of action type. ERP were computed during movie visual perception and analyzed as a function of movie type and task. The main result revealed a difference between ORA and NORA on the amplitude of the P3a component in the fronto-parietal region. The difference observed around 250 ms after movie onset do not likely origin from variation in low-level visual features or attention resource allocation. Instead, we suggest that it reflects incidental recruitment of object attributes during object-related action perception. The exact nature of these attributes is discussed.

Survey of the BY Draconis syndrome among dMe stars

Results are reported for a BVr photometric survey of 22 dK, dKe, dM, and dMe stars conducted to search for slow quasi-sinusoidal fluctuations in V (the BY Draconis syndrome). The (B-V) and (V-r) color indices are determined in an attempt to detect wavelength-dependent color changes produced by starspots and to infer starspot temperatures. It is found that nine of the stars exhibit variations in V of the order of 0.05 to 0.10 magnitude on a time scale of days or weeks, that at least three more display changes in mean light level over a period of years, that the stars generally tend to become redder at minimum light, and that some of the stars show no detectable color changes over their photometric cycle. The color data are taken to suggest a probable temperature difference of about 200 to 500 K between the stellar photospheres and starspots if the V variations are attributed to dark spots. It is concluded that the BY Draconis syndrome is clearly a very common occurrence among dMe stars.

Short time delays change pattern induced flicker colors (PIFCs)

Subjects decided on whether the colors of the rings on a modified Benham's top were the same or different. The cause of color differences was a variable time delay. Δt, of the black and white stimulus pattern on the disc. Time delays of Δt = 50 μsec and less caused detectable changes in color and brightness.

Microbiological deterioration of frozen parfried potatoes upon holding after thawing.

Frozen parfried potatoes were thawed and stored at 55, 45, and 34 F (12.8, 7.2, 1.1 C). Significant changes in flavor and texture did not occur at these temperatures until the total bacterial count exceeded 100 million per gram. These sensory changes were produced after 4, 8, and 20 days of storage at 55, 45, and 34 F, respectively. Detectable color change appeared sooner and probably was not of microbial origin. It is unlikely that any health hazard exists under the range of conditions studied. Nevertheless, it seems undesirable to market food with such a high bacterial count. At half the storage periods given above, the count did not exceed 100,000 per gram.

Microbiological Deterioration of Frozen Parfried Potatoes upon Holding After Thawing

Frozen parfried potatoes were thawed and stored at 55, 45, and 34 F (12.8, 7.2, 1.1 C). Significant changes in flavor and texture did not occur at these temperatures until the total bacterial count exceeded 100 million per gram. These sensory changes were produced after 4, 8, and 20 days of storage at 55, 45, and 34 F, respectively. Detectable color change appeared sooner and probably was not of microbial origin. It is unlikely that any health hazard exists under the range of conditions studied. Nevertheless, it seems undesirable to market food with such a high bacterial count. At half the storage periods given above, the count did not exceed 100,000 per gram.