1. 1.The sensations evoked by pairs of distinct thermal stimuli applied to the back of the hand were studied in 17 volunteer subjects. Four stimulus combinations were used; neutral-cold (NC), neutral-neutral (NN), neutral-warm (NW), and cold-warm (CW).
2. 2.The subjects were first asked to estimate the magnitude of the thermal sensations evoked by the thermal stimuli. On average, the four pairs were reported as increasing magnitude in the following order: NC, CW, NN, and NW, seeming to suggest that the subjects experienced the cold-warm combination as a composite sensation of cold and warmth intermediate between pure cold and pure warmth.
3. 3.When asked only to detect the presence of a cold stimulus, the subjects performed as well for the CW combination as for the CN combination. This second result indicates that the reported composite magnitude of CW does not result from a true opponency of cold and warmth but from a cognitive combination of distinct sensations of cold and warmth.
Author Keywords: Thermal sense; psychophysics; perception; sensory opponency; man 相似文献
Summary The yeast-like fungusAureobasidium is a promising source of xylanase (EC 3.2.1.8) with an exceptionally high specific activity. For enzyme production in volumes of several liters, xylose was the preferred carbon source and inducer. Xylanase in clarified cultures was concentrated by reversible adsorption to cation-exchange matrix to 5% of the initial volume, and recovered at nearly 2 million IU/1. Selective conditions permitted 97% recovery of xylanase with a 1.8-fold enrichment in specific activity, to 70% of purity. The predominant xylanase species (20 kDa) was subsequently purified to >99% of homogeneity by gel filtration chromatography. Purified enzyme exhibited an isoelectric point of 8.5, and specific activity of 2100 IU/mg under optimal conditions, determined to be pH 4.5 and 45°C. The activity of purified enzyme was specific for polymeric xylan.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Dept. of Agirculture over other firms or similar products not mentioned. 相似文献
By light microscopic investigation of skin and wool specimens of newborn lambs, we discovered a previously unknown mechanism for melanosomes transport in the process of dermal papilla melanocytes regular mitosis and migration into the hair shaft. This mechanism plays a great role in hair pigmentation especially in dominant (ED/ED) and recessive (Aa/Aa) black lambs of all investigated breeds. The rate of pigment cell mitosis, proliferation, and migration differs greatly in lambs of investigated color genotypes. In black genotypes the rate of melanocyte mitosis is very high and is approximately the same as in the hair bulb matrix cells, whereas in brown and red genotypes this rate is much lower. Melanocyte mitosis in the light red and tan groups was not found. 相似文献
The biological behavior of the pigmentary phenotypes of four breeds of cattle has been analysed: the black pigmentation of Holstein Friesian; the red pigmentation of Limousin; the dilution in Charolais; and the postnatal disappearance of red pigmentation in Chianina. The analytic techniques included the characterization of melanins by high-performance liquid chromatography, the examination of follicular melanocytes by light microscopy, and the examination of melanosomes by electron microscopy. The black phenotype was very strongly eumelanogenic. The red phenotype in Limousin is polymorphic: individual follicular melanocytes contain both mature eumelanosomes and pheomelanosomes. Charolais and Chianina cattle exhibited a dramatic reduction in melanogenic activity, which was characterized by the almost exclusive presence of prephaoemelanosomes in Charolais and of immature premelanosomes in Chianina. In the dilute Charolais phenotype, the density of distribution of follicular melanocytes also seemed to be reduced. The genes that are responsible for these four phenotypes seem to act on the maturation, differentiation, and density of distribution of the melanosomes. 相似文献
Necessary and sufficient spectral conditions are presented for Von Kries chromatic adaptation to give color constancy. Von-Kries-invariant reflectance spectra are computed for illuminant spectral power distributions that are arbitrary linear combinations of the first three daylight phases. Experiments are suggested to test models of color constancy using computed spectra (either exact or approximate) within the illuminant-invariant framework. 相似文献
Treatment of textile wastewater is a big challenge because of diverse chemical composition, high chemical strength and color of the wastewater. In the present study, treatment of wastewater containing reactive black-5 azo dye was studied in anaerobic sequencing batch bioreactor (SBBR) using mixed liquor suspended solids (MLSS) from suspended and attach growth bioreactors. MLSS at concentration of 1000 mg/L and reactive black-5 azo dye at 100 mg/L were used. A culture (108–109 CFU/ml) of pre-isolated bacterial strains (Psychrobacter alimentarius KS23 and Staphylococcus equorum KS26)) capable of degrading azo dyes in mineral salt medium was used to accelerate the treatment process in bioreactor. Different combinations of sludge, culture and dye were used for treatment using different co-substrates. About 85% COD removal was achieved by consortium (MLSS + KS23 + KS26) after 24 h in attach growth bioreactor. Similarly, 92% color removal was observed with consortium in attach growth bioreactor compared to 85% color removal in suspended bioreactor. Addition of bacterial culture (20%, v/v) to the bioreactor could enhance the rate of color removal. This study suggests that biotreatment of wastewater containing textile dyes can be achieved more efficiently in the attach growth bioreactor using yeast extract as a co-substrate and MLSS augmented with dye-degrading bacterial strains. 相似文献