scholarly journals THE TIME DIFFERENCE IN EMISSION OF LIGHT AND PRESSURE PULSES FROM OSCILLATING BUBBLES

2018 ◽  
Vol 58 (5) ◽  
pp. 323
Author(s):  
Karel Vokurka
Keyword(s):  
Bubble Size ◽  
Light Flash ◽  
Time Difference ◽  
Intensity Maximum ◽  
Bubble Oscillation ◽  
Maximum Value ◽  
Oscillating Bubbles ◽  
Oscillation Intensity ◽  
Pressure Pulses ◽  
Light Flashes

Oscillations of spark-generated bubbles are studied experimentally. In this work, an attention is paid to the time difference in the radiation of light flashes and pressure pulses from a bubble at the final stages of the first bubble contraction and the early stages of the first bubble expansion. It is found that light and pressure pulses are not radiated synchronously. In some experiments, the light flashes are radiated before the pressure pulses by a few μs and in other experiments, the light flashes are radiated later than the pressure pulses by a few μs. The time difference in the radiation of the two pulses is examined in detail in relation with the bubble size, bubble oscillation intensity, maximum value of the light flash and the width of the light flash. It is shown that the magnitude of the time differences is very weakly correlated with the bubble size, intensity of oscillation and intensity of the light flashes and that the magnitude of the time differences is only moderately correlated with the light flashes widths.

Particle pressures generated around bubbles in gas-fluidized beds

2002 ◽  
Vol 455 ◽  
pp. 103-127 ◽  
Author(s):  
KHURRAM RAHMAN ◽  
CHARLES S. CAMPBELL
Keyword(s):  
Fluidized Bed ◽  
Bubble Size ◽  
Fluidized Beds ◽  
Gas Flow ◽  
Solid Particles ◽  
Particle Phase ◽  
Fluid Mixture ◽  
Maximum Value ◽  
Particle Pressure ◽  
Gas Fluidized Beds

The particle pressure is the surface force in a particle/fluid mixture that is exerted solely by the particle phase. This paper presents measurements of the particle pressure on the faces of a two-dimensional gas-fluidized bed and gives insight into the mechanisms by which bubbles generate particle pressure. The particle pressure is measured by a specially designed ‘particle pressure transducer’. The results show that, around single bubbles, the most significant particle pressures are generated below and to the sides of the bubble and that these particle pressures steadily increase and reach a maximum value at bubble eruption. The dominant mechanism appears to be defluidization of material in the particle phase that results from the bubble attracting fluidizing gas away from the surrounding material; the surrounding material is no longer supported by the gas flow and can only be supported across interparticle contacts which results in the observed particle pressures. The contribution of particle motion to particle pressure generation is insignificant.The magnitude of the particle pressure below a single bubble in a gas-fluidized bed depends on the bubble size and the density of the solid particles, as might be expected as the amount of gas attracted by the bubble should increase with bubble size and because the weight of defluidized material depends on the density of the solid material. A simple scaling of these quantities is suggested that is otherwise independent of the bed material.In freely bubbling gas-fluidized beds the particle pressures generated behave differently. Overall they are smaller in magnitude and reach their maximum value soon after the bubble passes instead of at eruption. In this situation, it appears that the bubbles interact with one another in such a way that the de uidization effect below a leading bubble is largely counteracted by refluidizing gas exiting the roof of trailing bubbles.

Persistence of phytochrome-mediated germination control in lettuce seeds for 1 year following a single monochromatic light flash

1972 ◽  
Vol 50 (4) ◽  
pp. 687-689 ◽  
Author(s):  
William Vidaver ◽  
A. I-hsiung Hsiao
Keyword(s):  
Light Flash ◽  
Red Light ◽  
Monochromatic Light ◽  
Entire Period ◽  
Lettuce Seeds ◽  
Light Flashes

The effects of red or far-red light flashes on partially hydrated lettuce seeds were found to be undiminished by subsequent dry, dark storage for more than 1 year before germination. Upon rehydration of the seeds photoreversal of the latent response could be induced by a red or far-red light flash at any time during the entire period.

Ultrastructural Investigation of the “Light Flash” Phenomenon Seen by our Astronauts

1972 ◽  
Vol 30 ◽  
pp. 52-53
Author(s):  
Delbert E. Philpott ◽  
R. Corbett ◽  
Sam Black ◽  
Charles Turnbill
Keyword(s):  
Light Flash ◽  
The Other ◽  
Lawrence Radiation Laboratory ◽  
X Rays ◽  
The Moon ◽  
Ultrastructural Investigation ◽  
Pocket Mouse ◽  
Radiation Laboratory ◽  
First Time ◽  
Light Flashes

The light flashes seen by astronauts on their flights to the moon are believed to be caused by “heavy primaries” passing through the eyes. In order to learn more about this phenomenon and its effect on the retina, pocket mouse retinas were exposed to nitrogen beams (the heaviest nuclei available at Lawrence Radiation Laboratory) and also the evoked response from X-rays on rabbit eyes was observed.Pocket mouse retinas were exposed to nitrogen beams for the first time in the Berkeley Bevatron Accelerator. The pocket mice were positioned so as to expose one eye while the other eye was left unexposed. Both eyes were compared with controls (Fig. 1).

scholarly journals Long- and short-range bimodal signals mediate mate location and recognition in yellow fever mosquitoes

2021 ◽  
Author(s):  
Elton Ko ◽  
Chiara Lier ◽  
Adam J. Blake ◽  
Stephen Takács ◽  
Gerhard Gries
Keyword(s):  
Yellow Fever ◽  
Mate Selection ◽  
Short Range ◽  
Light Flash ◽  
Mate Recognition ◽  
Mate Location ◽  
Small Space ◽  
Flashing Light ◽  
Light Flashes ◽  
Swarm Formation

AbstractAs recently reported, light flashes of incident sunlight reflecting off the wings of in-flight dipterans serve as mate recognition signals. Mate location and mate selection behavior in the yellow fever mosquito, Aedes aegypti, take place in mating swarms but the mechanisms underlying swarm formation and long-range detection of females by males remain largely unexplored. Here we show that swarm formation and mate recognition are mediated, in part, by light flash signals and wingbeat sound signals that operate at long and short range, respectively. To test for range-dependent effects of these signals, we presented ‘mating swarms’ in form of two paired 8-LED assemblies that were fitted with micro-speakers and placed either well separated in a large space or side-by-side in a small space. In the large but not the small space, the LED assembly flashing light at the wingbeat frequency of females (665 Hz), and emitting their wingbeat sound (665 Hz), attracted and prompted 5.8-times more alightings by males than the LED assembly emitting constant light and wingbeat sound. In the small space, the LED assembly flashing light and emitting wingbeat sound induced 5.0-times more alightings by males than the LED assembly flashing light without wingbeat sound. Females responded to light flash signals of males, but males failed to respond to the synthetic female pheromone component ketoisophorone added to the bimodal complex of light and sound signals. The attractiveness of light flash signals to males increased with increasing numbers of signals but did not vary according to their wavelengths (UV or blue). As predicted by the sensory drive theory, light flashes had no signal function for crepuscular house mosquitoes, Culex pipiens.

scholarly journals ON THE SECOND LIGHT FLASH EMITTED FROM A SPARK-GENERATED BUBBLE OSCILLATING IN WATER

2020 ◽  
Vol 60 (3) ◽  
pp. 268-278
Author(s):  
Karel Vokurka
Keyword(s):  
Light Flash ◽  
Early Stages ◽  
Light Flashes

The light emitted from the spark-generated bubbles oscillating in water is studied experimentally. Attention is paid to the emission of light from bubbles in the final stages of their first contraction and in the early stages of their following expansion. In some experiments, two close flashes of light were observed. The first light flash has already been studied in earlier works. In the present work, attention is paid to the second light flash. The relations between the first and second flashes of light and the size of the bubbles are studied and discussed in detail. It is assumed that these two light flashes are caused by two different processes taking place in the bubbles. The possible nature of these two processes is briefly discussed.

scholarly journals Implementation Of The Evaluation Of The Volume Of Maximum Oxygen Uptake (Vo2 Max) Athletes Koni Rokan Hulu

2021 ◽  
Vol 2 (1) ◽  
pp. 1-5
Author(s):  
Ridwan Sinurat
Keyword(s):  
Oxygen Uptake ◽  
The Body ◽  
Maximum Oxygen Uptake ◽  
Maximum Volume ◽  
Intensity Maximum ◽  
Direct Examination ◽  
Vo2 Max ◽  
Physical Conditions ◽  
Maximum Value

The quality of maximum oxygen volume (VO2max) for athletes is important for an athlete's performance. VO2Max is the maximum volume of oxygen that can be used per minute. The maximum amount of oxygen consumed per unit time by a person during exercise or tests, with training progressively heavier until exhaustion, is called VO2Max. The Vo2Max Direct examination is the most accurate test in determining the level of heart and lung fitness in performing physical activities with maximum intensity. Maximum oxygen uptake (Vo2max) is defined as the maximum value at which oxygen can still be taken, distributed, and used by the body when the intensity of physical activity reaches its maximum. This service method provides material on the importance of evaluating physical conditions, especially Vo2max to athletes. This service aims to help the Indonesian National Sports Committee (KONI) Rokan Hulu Regency to find out the fitness of athletes from several sports as seen from VO2 Max. The method used in this service is that all athletes follow the service's direction about the importance of VO2 Max and perform a Multistage Fitness Test (MFT). The results of this dedication by the athletes and management of KONI understand the importance of VO2 Max and the results of the MFT test, only a few athletes in good and other categories are sufficient and low.

scholarly journals On the morphology of elytra as luminescent organs in scale-worms (Polychaeta, Polynoidae)

Zoosymposia ◽  
2009 ◽  
Vol 2 (1) ◽  
pp. 379-389 ◽  
Author(s):  
MARIA PLYUSCHEVA ◽  
DANIEL MARTIN
Keyword(s):  
Marine Invertebrates ◽  
Light Flash ◽  
Basal Layer ◽  
Dorsal Surface ◽  
Sensory Organs ◽  
Electrochemical Coupling ◽  
Light Flashes

Polynoid polychaetes are common marine invertebrates worldwide that are characterized by bearing series of paired elytra attached to dorsal prominences (the elytrophores) arising from the notopodia, and whose dorsal surface is usually ornamented with different papillae (usually thought to be sensory organs). Upon stimulation, some species of the sub-family Polynoinae are able to emit light flashes from the ventral epithelium of the elytra. This bioluminescence originates in a protein called polynoidin, and seems to be induced by the destruction of the electrochemical coupling between body and elytra when the latter are detached. However, the elytral structure, as well as the function of the papillae and tubercles in relation to the bioluminescence is poorly known. In this paper, we report on the elytral morphology of two “luminescent” and two “non-luminescent” (Nicol 1953) species from the White and Mediterranean Seas. In both polynoid types, the elytral tubercles are formed by a layer of hard, non-organized, autofluorescent tissue, apparently filled by expansions protruding from cells forming a distinct subjacent layer. Our study allowed us to suggest that the luminescent protein is located in the cells of the basal layer, while the tubercles may act as lenses helping in the light flash transfer towards the exterior. The reasons why the studied species are or are not bioluminescent are discussed.

Experimental study of light emitted by spark-generated bubbles in water

2018 ◽  
Vol 81 (1) ◽  
pp. 11101
Author(s):  
Karel Vokurka ◽  
Silvano Buogo
Keyword(s):  
Experimental Study ◽  
Bubble Size ◽  
Leading Edge ◽  
Weak Correlation ◽  
Optical Pulses ◽  
Trailing Edge ◽  
Early Stages ◽  
Light Pulses ◽  
Light Flashes

The emission of light from spark-generated bubbles freely oscillating in water far from boundaries is studied experimentally. The observations concentrate on light flashes radiated at final stages of the first bubble contraction and early stages of the following bubble expansion. It is shown that the shape of the emitted light pulses is not “Gaussian”, but asymmetric with a leading edge moderately growing and a trailing edge steeply decreasing. The maximum values and widths of these optical pulses are determined for bubbles having different sizes and oscillating with different intensities. The variation of the maximum values and pulse widths with bubble size and intensity of oscillation is discussed, as well as the observed weak correlation between these two quantities.

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