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Using multiple lines of evidence, it was determined that the young age scenario was most likely, with evidence for an age close to 20 years using a series of deductions in the bomb 14 C dating method. Comparative growth, age at maturity and sex change, and longevity of Hawaiian parrotfishes, with bomb radiocarbon validation.

Growth rates and longevities were estimated for five major fishery species of parrotfishes " uhu " at Oahu, Hawai'i.

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Longevities were found to range Longevities were found to range broadly among the three small species, 4 years in Calotomus carolinus and 6 and 11 years in Scarus psittacus and Chlorurus spilurus, and to 15—20 years in Scarus rubroviolaceus and Chlorurus perspicillatus for the two large species. Age reading and growth curves for the latter two large species were validated using bomb radiocarbon dating. Median ages at sexual maturity as females A M50 and at sex change from female to terminal phase male, A 50 were estimated using logistic models.

Sexual maturation occurred at 1—2 years for the small species and at 3—3. A 50 estimates ranged from 2 to 4 years in the small species and were about 5 and 7 years in S. Estimated milestones poorly corresponded to the current minimum legal size for uhu in Hawai'i 12 in.

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Pooling these parrotfishes for management seems generally inappropriate, especially for the two large species. Age-based metrics are more informative than size-based metrics for these fishes. Evidence for magmatic carbon bias in 14 C dating of the Taupo and other major eruptions. Prehistoric timescales, volcanic hazard assessment, and understanding of volcanogenic climate events rely on accurate dating of prehistoric eruptions.

Most late Quaternary eruptions are dated by 14 C measurements on material from close to Most late Quaternary eruptions are dated by 14 C measurements on material from close to the volcano that may be contaminated by geologic-sourced infinite-age carbon.

Here we show that 14 C ages for the Taupo New Zealand First Millennium eruption are geographically arrayed, with oldest ages closer to the vent. We present evidence that the older, vent-proximal 14 C ages were biased by magmatic CO 2 degassed from groundwater, and that the Taupo eruption occurred decades to two centuries after CE. Our reinterpretation implies that ages for other proximally-dated, unobserved, eruptions may also be too old. We are leading top modeling agency for music producers, talents and models in Singapore.


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We have model talents agency for you in Singapore. Consumption of marine protein in humans and animals can result in an apparent older 14 C age due to reservoir offsets. In order to correct for this, an estimate of the marine protein intake should be used to correct the 14 C age for However, these two isotopic proxies can be influenced by a number of factors which can hamper estimation of the correct marine protein intake. A small dataset of 12 samples from the Limfjord,. Impact of climate and humans on the range dynamics of the woolly mammoth Mammuthus primigenius in Europe during MIS 2.

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The woolly mammoth Mammuthus primigenius was widespread in almost all of Europe during the late Pleistocene. However, its distribution changed because of population fluctuations and range expansions and reductions. The Greenland stadial 3 interval It is not clear whether mammoths survived in the East European Plain. No significant correlation was found between the distribution of the mammoth in Europe and human activity.

Unlike other cart ruts found elsewhere in the world, the Azorean cart-ruts, engraved on volcanic stone, at the middle of the Atlantic, raise many questions: How old are they?

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Were they made during a short or long time? These mysteriously enigmatic parallel grooves are noticed on the hard volcanic rock of the nine Azorean Islands in several locations.

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Recent scientific evidences have provided some support to the hypothesis of human presence in the Azores Islands before Portuguese settlement during the 15 th century. Are the Azorean cart-ruts pre-Portuguese? Here we try to establish a chronology for the cart-ruts of Terceira Island, Azores, Portugal, using an historical approach, a geological approach and also a 14 C dating approach , the last one obtained by dating a placic horizon found in the grooves of the cart-ruts named " Passage of the Beasts " , which indicates the presence of human activity in the island at least during the 11 th century, or probably before.

The date obtained is consistent with another date achieved through similar methods for a man-made basin in the same island and is also consistent with the historiographical records. Asian dating sites are very popular and a great way to find love. There are many to chose from, but finding the right one to join can be difficult with the large amount available to chose from. Current issues for radiocarbon dating in Iron Age Israel. The purpose of the preparation of samples before radiocarbon measurement is the extraction of material that contains indigenous carbon in a quantity sufficient to measure the 14 C content, remove contaminating substances which usually give different age, and produce the medium for appropriate measurement technique e.

CO 2 for gas proportional counters or graphite for AMS. The procedure of treatment depends on the sample material. Usually the samples need physical cleaning or separation under microscope. Most commonly the AAA acid-alkali-acid method is used for organic samples like charcoal or organic remains. Shells are cleaned and the outer part is dissolved in a weak acid.

For bones the collagen is extracted according to the modified Longin's method see poster. After the chemical pretreatment the sample material in a quantity corresponding to ca. The tube with the CO 2 derived from the sample is incised and placed into an arm of a vacuum line with a ball joint. After overnight pumping to high vacuum 10 -4 mbar the arm is cut off with a cock and the tube is cracked and gas released.

Water vapour is frozen in a trap cooled with a mixture of dry ice and alcohol ca. The amount of obtained CO 2 is measured and the excess of gas is removed or stored in a separate vial.

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Production of substances and chemical preparations with a specific formulation; conducting technological research regarding product synthesis, isolation and purification. Performing 14C tests with the most modern accelerator technique AMS: Clients are scientific institutions in the field of archeology, art history, geology, geomorphology, paleoclimatology, palaeobotany, biochemistry, food industry, etc.

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