scholarly journals Commentary on Effects of Anthropogenic and Natural Organic Chemicals on Development, Swimming Behavior, and Reproduction of Daphnia, a Key Member of Aquatic Ecosystems

1995 ◽  
Vol 103 ◽  
pp. 7 ◽  
Author(s):  
Stanley I. Dodson ◽  
Takayuki Hanazato
Keyword(s):  
Aquatic Ecosystems ◽  
Swimming Behavior ◽  
Organic Chemicals

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

A study on the visualization of the swimming behavior of sandfish (Arctoscopus japonicus)

2016 ◽  
Vol 9 (1) ◽  
pp. 60
Author(s):  
Yongbeom PYEON ◽  
Eunseok YANG ◽  
Shinku KANG ◽  
Kyunghoon LEE
Keyword(s):  
Swimming Behavior
Sign in / Sign up

Export Citation Format

Share Document