Experiments on the Light Sense of the Hag, Myxine Glutinosa L

1955 ◽  
Vol 32 (1) ◽  
pp. 22-38
Author(s):  
D. M. STEVEN
Keyword(s):  
Reaction Time ◽  
Spectral Sensitivity ◽  
Sea Water ◽  
Locomotory Activity ◽  
Spectral Transmission ◽  
Sensitivity Maximum ◽  
Myxine Glutinosa ◽  
Minimum Value ◽  
Functional Value ◽  
Local Movement

1. The response of the hag to light consists of one or more local movements followed after a further interval by general locomotory activity. The first local movement has been used as a measure of the reaction time. 2. The reaction time is inversely proportional to the intensity of the stimulus at illuminations less than about 10 e.f.c. At higher levels of illumination it attains a constant minimum value. Hags respond to intensities at least as low as 0.1 e.f.c. but only after several minutes illumination. 3. Estimates of the penetration of light through sea water suggest that the hag's light sense is of functional value. 4. The spectral sensitivity maximum lies between 500 and 520 mµ. Hags are virtually insensitive to wave-lengths longer than about 600 mµ. 5. The significance of the spectral sensitivity is discussed in relation to the spectral transmission of sea water and the evolution of photosensitive systems.

scholarly journals The Respirable Organic Matter of Sea Water

1922 ◽  
Vol 12 (4) ◽  
pp. 772-780 ◽  
Author(s):  
W. R. G. Atkins
Keyword(s):  
Organic Matter ◽  
Oxygen Consumption ◽  
Carbonic Acid ◽  
Sea Water ◽  
Ph Value ◽  
Complete Oxidation ◽  
English Channel ◽  
Estuarine Waters ◽  
Minimum Value ◽  
Alkaline Permanganate

1. On storing, sea water suffers a decrease in pH value. The amount of change varies from that produced by adding 1·0 c.c. of N/100 acid to 100 c.c. of sea water, up to that due to adding about 2·5–3·0 c.c. The decrease is due to the production of carbonic acid by organisms.2. The change corresponding to 1·0 c.c. of acid, as above, is equivalent to that produced by the complete oxidation of 3 milligrams per litre of a hexose sugar, which requires 3·2 mgrms. per litre of oxygen. This is the minimum value, from 8·0–9·6 mgrms. corresponds to the higher values of acid. Figures for oxygen consumption by estuarine waters, which are available for an approximate comparison, show that 1·5 mgrms. of oxygen is not often exceeded in estimations by means of alkaline permanganate. The highest of this series is 5·6 mgrms. It is suggested that the different results given by the two methods are due to the fact that respiratory changes taking place in the water during storage set free much of the organically combined carbon before the oxidation by permanganate has been started. Determinations on freshly drawn filtered sea water give, according to Raben, 7·5 mgrms. of hexose or 8·0 mgrms. of oxygen consumed.3. It is probable that the change in pH value on storing indicates the amount of plankton present, at any rate when sewerage contamination is negligible. It appears that water near the surface, at 20–25 metres and sometimes at the bottom, 70 metres, is particularly subject to change during storage. Four cases out of seven showed marked decreases in pH value at 20–25 metres, and two others exhibited the change to a less marked degree.4. The total amount of carbon, reckoned as hexose, which is set free during storage by respiration in sea water at E1 is about twice that photosynthesised between July and December, taking for this the minimum value 3 mgrms. per litre, namely a total of 6 mgrms. per litre. Considering the column of water from bottom to surface, this is equivalent to about 500,000 kilograms per square kilometre in the English Channel off Plymouth.

Study on Catalytic Degradation of Diesel Pollution in Seawater by Laccase

2013 ◽  
Vol 781-784 ◽  
pp. 2324-2327
Author(s):  
Xu Zheng ◽  
Xiao Cai Yu ◽  
Yun Qing Liu ◽  
Xiao Xv ◽  
Jin Fang Chen
Keyword(s):  
Reaction Time ◽  
Reaction Temperature ◽  
Sea Water ◽  
Oil Pollution ◽  
Ph Value ◽  
Degradation Process ◽  
Catalytic Degradation ◽  
Initial Concentration ◽  
Optimization Study ◽  
Optimum Reaction

Sea water joining diesel was selected to prepare simulated marine oil pollution. With the target of removing diesel from seawater, the influence of various factors on the laccase-catalyzed degradation process was discussed. The experimental results show that the laccase-catalyzed degradation process was significantly affected by laccase dosage, reaction temperature, reaction time, pH of the solution and initial concentration of diesel in the oily wastewater. A systematic optimization study was carried out through a orthogonal test on the basis of the results of the single-factor experiments,and the optimum reaction conditions of laccase catalytic degradation diesel pollutants in seawater was determined. The results indicate that under the conditions of diesel initial concentration of 0.1g/L, laccase dosage of 8mg/L, pH value of 6, the reaction temperature of 25°C and the reaction time of 4h, laccase catalytic degradation rate of diesel pollution can be up to 63.85%.

Tidal and Diurnal Rhythms of Locomotory Activity in Carcinus Maenas (L.)

1958 ◽  
Vol 35 (3) ◽  
pp. 602-610
Author(s):  
E. NAYLOR
Keyword(s):  
High Activity ◽  
Sea Water ◽  
High Tide ◽  
Carcinus Maenas ◽  
Diurnal Rhythms ◽  
Locomotory Activity ◽  
The Hours ◽  
Resultant Effect ◽  
Observed Behaviour ◽  
Dim Light

1. Spontaneous locomotory activity was recorded continuously for several days in Carcinus maenas (L.). 2. A complex rhythm was observed which could be analysed into two components, one of diurnal frequency (24 hr.), with peaks of activity during the hours of darkness, and one of tidal frequency (ca. 12.4hr.), with peaks at the time of high tide. 3. The rhythms persist in constant dim light at constant temperatures, whether the crabs are kept moist in air or continuously immersed in sea water. 4. The resultant effect of the two rhythms is to produce particularly high activity peaks during periods which recur with a semi-lunar frequency. 5. Experimental results relate to observed behaviour on the shore.

The spectral sensitivity of Hydra carnea L. Agassiz (1850)

1970 ◽  
Vol 48 (1) ◽  
pp. 63-68 ◽  
Author(s):  
Virginia L. Ellis
Keyword(s):  
Growth Rate ◽  
Reaction Time ◽  
Spectral Sensitivity ◽  
White Light ◽  
Red Light ◽  
Action Spectrum ◽  
Green Light ◽  
Reaction Times ◽  
Light Stimuli ◽  
Hydra Carnea

The spectral sensitivity of Hydra carnea was investigated by growth rate and action spectrum studies. The rate of asexual growth was measured over a 40-day period for animals cultured under white, blue, green, and red lights of equal intensity. The growth rate was greatest under red light and slowest under blue; the rate under white light was similar to that under green light. The action spectrum, measured as the reaction times to light stimuli of various wavelengths, varied according to the light under which the animals were cultured. For H. carnea that had been cultured in the dark, the reaction time was shortest at 650 nm and longest at 450 nm when lights of equal intensity were used. This differs from the results of an earlier study with H. pirardi, which showed maximum sensitivity to blue light. Animals cultured under blue, green, and red lights showed a decreased sensitivity, indicated by an increased reaction time, to the light under which they were cultured as compared to animals cultured in the dark.

REACTION TIME AND INTELLIGENCE

1991 ◽  
Vol 1 (1) ◽  
pp. 211-221 ◽  
Author(s):  
Edward Neçka
Keyword(s):  
Reaction Time

Modeling Within-Person Variance in Reaction Time Data of Older Adults

GeroPsych ◽  
2011 ◽  
Vol 24 (4) ◽  
pp. 169-176 ◽  
Author(s):  
Philippe Rast ◽  
Daniel Zimprich
Keyword(s):  
Reaction Time ◽  
Cognitive Aging ◽  
Reaction Times ◽  
Reaction Time Task ◽  
Reaction Time Data ◽  
Scale Model ◽  
Time Data ◽  
Time Task ◽  
The Mean ◽  
Second Wave

In order to model within-person (WP) variance in a reaction time task, we applied a mixed location scale model using 335 participants from the second wave of the Zurich Longitudinal Study on Cognitive Aging. The age of the respondents and the performance in another reaction time task were used to explain individual differences in the WP variance. To account for larger variances due to slower reaction times, we also used the average of the predicted individual reaction time (RT) as a predictor for the WP variability. Here, the WP variability was a function of the mean. At the same time, older participants were more variable and those with better performance in another RT task were more consistent in their responses.

The Level of Reaction Time Determines the ERP Correlates of Auditory Negative Priming

2006 ◽  
Vol 20 (3) ◽  
pp. 186-194 ◽  
Author(s):  
Susanne Mayr ◽  
Michael Niedeggen ◽  
Axel Buchner ◽  
Guido Orgs
Keyword(s):  
Reaction Time ◽  
Negative Priming ◽  
Effect Size ◽  
Priming Effect ◽  
Reaction Times ◽  
Negative Priming Effect ◽  
Episodic Retrieval ◽  
Time Level ◽  
Fast Reactions ◽  
Priming Condition

Responding to a stimulus that had to be ignored previously is usually slowed-down (negative priming effect). This study investigates the reaction time and ERP effects of the negative priming phenomenon in the auditory domain. Thirty participants had to categorize sounds as musical instruments or animal voices. Reaction times were slowed-down in the negative priming condition relative to two control conditions. This effect was stronger for slow reactions (above intraindividual median) than for fast reactions (below intraindividual median). ERP analysis revealed a parietally located negativity of the negative priming condition compared to the control conditions between 550-730 ms poststimulus. This replicates the findings of Mayr, Niedeggen, Buchner, and Pietrowsky (2003) . The ERP correlate was more pronounced for slow trials (above intraindividual median) than for fast trials (below intraindividual median). The dependency of the negative priming effect size on the reaction time level found in the reaction time analysis as well as in the ERP analysis is consistent with both the inhibition as well as the episodic retrieval account of negative priming. A methodological artifact explanation of this effect-size dependency is discussed and discarded.

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