scholarly journals Bubbles to Chondrites-I. Evaporation and condensation experiments, and formation of chondrules

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Yuki Nakano ◽  
Akihiko Hashimoto
Keyword(s):  
Redox State ◽  
Maximum Size ◽  
Vapor Bubbles ◽  
Formation Model ◽  
Size Frequency Distribution ◽  
Evaporation And Condensation ◽  
Boiling Points ◽  
Vapor Cloud ◽  
Gas Cooling ◽  
Chondrule Formation

Abstract We propose a simple model of chondrule formation that is supported by our new experiments. With a laser-heating and inert-gas-cooling technique, we obtained evaporation and condensation pathways starting with chondritic compositions till ends, and extracted ‘relative volatilities’ of elements from them. Above boiling points, we observed numerous silicate droplets being ejected from collapsed cavities of vapor bubbles on the surface of molten sample, known as jet-droplets. We postulate jet-droplets as origin of chondrules. The formation mechanism of jet-droplets requires a dense and large solid body (>3 cm across), named ‘duston’, for chondrule precursors. Our chondrule formation model presumes dustons having CI-like composition. Upon boiling, a duston ejects jet-droplets from its molten surface and simultaneously forms an adiabatically expanding vapor cloud around it. The jet-droplets supercool and incorporate the supersaturated vapor and fine condensates while they travel through the cloud, thus completing their makeup as chondrules. The compositions and the mixing ratio of the three components (jet-droplet, vapor and condensate) can be exactly predicted by using relative volatilities of elements, given the chondrule composition to be fitted and the conditions: vaporization degree (VD) and redox state (fs) of the duston. We attempt to reproduce bulk compositions of chondrules in total of 600. About 75% chondrules are successfully matched with specific combinations of VD and fs for each chondrule. The model altogether explains 3.5 features of chondrules: maximum size and size-frequency distribution; chemical variety; and textural variety.

Age, growth, and reproduction of the rock goby, Gobius paganellus L., in the Isle of Man

1961 ◽  
Vol 41 (3) ◽  
pp. 737-769 ◽  
Author(s):  
P. J. Miller
Keyword(s):  
Breeding Season ◽  
Sexual Maturity ◽  
Survival Curve ◽  
Age Groups ◽  
Maximum Size ◽  
Gonad Maturation ◽  
Corpora Lutea ◽  
Size Frequency Distribution ◽  
Isle Of Man ◽  
Growth And Reproduction

SUMMARYAge, growth and reproduction of the intertidal teleost, Gobius paganellus, has been investigated in the Isle of Man from March 1959 to September 1960. Samples were obtained by poisoning shore pools with a rotenone emulsion.Age was determined by examination of otoliths where a translucent annual ring is laid down in spring. Although the potential life span is at least 10 years, immature fishes of the first two age-groups constitute most of the population. An onshore breeding migration is postulated. An empirical survival curve indicates a high mortality rate during the first two years of life. Instances of predation on G. paganellus are given.Growth in length is logarithmic, with marked decrease in growth rate from about the age of sexual maturity. During the year, growth occurred from June to October. Maximum standard lengths recorded were 92*5 mm (feThe overall sex ratio of females to males was 1:1-326; this predominance of males persisted through the age-groups. The reproductive organs are briefly described, and a classification of gonad maturation is proposed. The breeding season lasted from mid-April to mid-June. Sexual maturity was reached at the end of the second or third year of life. Smallest ripening individuals found were 48-5 mm (female) and 505 (male). Fecundity increased with body size. Eggs were deposited on stones in shore pools and guarded by the male. Post-larvae occurred in pools from the beginning of July, and the first demersal individuals from August. Size-frequency distribution of oocytes in the ovary indicates that at least two broods may be produced in a single breeding season.In maximum size, longevity, and age at maturity, G. paganellus differs from other European gobies so far studied. It is suggested that a similar life history is exhibited by other British species of Gobius. The short breeding season of G. paganellus in the Isle of Man is held to be a result of proximity to the northern limit of distribution of this species. Examples of this phenomenon in other teleosts are provided. The significance of pre-ovulatory corpora lutea in the ovary of G. paganellus is briefly discussed.

EVAPORATION AND CONDENSATION IN 3He-4He MIXTURE SYSTEMS

1978 ◽  
Vol 39 (C6) ◽  
pp. C6-194-C6-195
Author(s):  
S. Ohta ◽  
Y. Sawada
Keyword(s):  
Evaporation And Condensation

Continuous Quantitative Monitoring of Mural, Platelet-Dependent, Thrombus Kinetics in the Crushed Rat Femoral Vein

1991 ◽  
Vol 65 (04) ◽  
pp. 425-431 ◽  
Author(s):  
F Stockmans ◽  
H Deckmyn ◽  
J Gruwez ◽  
J Vermylen ◽  
R Acland
Keyword(s):  
Thrombus Formation ◽  
Femoral Vein ◽  
Maximum Size ◽  
Digital Analysis ◽  
Video Recordings ◽  
Quantitative Monitoring ◽  
Set Up ◽  
Kinetics Of ◽  
Quantitative Nature

SummaryA new in vivo method to study the size and dynamics of a growing mural thrombus was set up in the rat femoral vein. The method uses a standardized crush injury to induce a thrombus, and a newly developed transilluminator combined with digital analysis of video recordings. Thrombi in this model formed rapidly, reaching a maximum size 391 ± 35 sec following injury, after which they degraded with a half-life of 197 ± 31 sec. Histological examination indicated that the thrombi consisted mainly of platelets. The quantitative nature of the transillumination technique was demonstrated by simultaneous measurement of the incorporation of 111In labeled platelets into the thrombus. Thrombus formation, studied at 30 min interval in both femoral veins, showed satisfactory reproducibility overall and within a given animalWith this method we were able to induce a thrombus using a clinically relevant injury and to monitor continuously and reproducibly the kinetics of thrombus formation in a vessel of clinically and surgically relevant size

Persistence of giants: population dynamics of the limpet Scutellastra laticostata on rocky shores in Western Australia

2020 ◽  
Vol 646 ◽  
pp. 79-92
Author(s):  
RE Scheibling ◽  
R Black
Keyword(s):  
Population Dynamics ◽  
Western Australia ◽  
Size Structure ◽  
Survival Rates ◽  
Maximum Size ◽  
High Rate ◽  
Adult Survival ◽  
Rocky Shores ◽  
Adult Size ◽  
Decadal Time Scale

Population dynamics and life history traits of the ‘giant’ limpet Scutellastra laticostata on intertidal limestone platforms at Rottnest Island, Western Australia, were recorded by interannual (January/February) monitoring of limpet density and size structure, and relocation of marked individuals, at 3 locations over periods of 13-16 yr between 1993 and 2020. Limpet densities ranged from 4 to 9 ind. m-2 on wave-swept seaward margins of platforms at 2 locations and on a rocky notch at the landward margin of the platform at a third. Juvenile recruits (25-55 mm shell length) were present each year, usually at low densities (<1 m-2), but localized pulses of recruitment occurred in some years. Annual survival rates of marked limpets varied among sites and cohorts, ranging from 0.42 yr-1 at the notch to 0.79 and 0.87 yr-1 on the platforms. A mass mortality of limpets on the platforms occurred in 2003, likely mediated by thermal stress during daytime low tides, coincident with high air temperatures and calm seas. Juveniles grew rapidly to adult size within 2 yr. Asymptotic size (L∞, von Bertalanffy growth model) ranged from 89 to 97 mm, and maximum size from 100 to 113 mm, on platforms. Growth rate and maximum size were lower on the notch. Our empirical observations and simulation models suggest that these populations are relatively stable on a decadal time scale. The frequency and magnitude of recruitment pulses and high rate of adult survival provide considerable inertia, enabling persistence of these populations in the face of sporadic climatic extremes.

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