36 research outputs found

    Re-examining the transition into the N=20 island of inversion: structure of 30Mg

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    Intermediate energy single-neutron removal from 31^{31}Mg has been employed to investigate the transition into the N=20 island of inversion. Levels up to 5~MeV excitation energy in 30^{30}Mg were populated and spin-parity assignments were inferred from the corresponding longitudinal momentum distributions and γ\gamma-ray decay scheme. Comparison with eikonal-model calculations also permitted spectroscopic factors to be deduced. Surprisingly, the 02+^{+}_{2} level in 30^{30}Mg was found to have a strength much weaker than expected in the conventional picture of a predominantly 2p−2h2p - 2h intruder configuration having a large overlap with the deformed 31^{31}Mg ground state. In addition, negative parity levels were identified for the first time in 30^{30}Mg, one of which is located at low excitation energy. The results are discussed in the light of shell-model calculations employing two newly developed approaches with markedly different descriptions of the structure of 30^{30}Mg. It is concluded that the cross-shell effects in the region of the island of inversion at Z=12 are considerably more complex than previously thought and that np−nhnp - nh configurations play a major role in the structure of 30^{30}Mg.Comment: Physics Letters B, Volume 779, 10 April 2018, Pages 124-12

    Social–environmental drivers inform strategic management of coral reefs in the Anthropocene

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    Without drastic efforts to reduce carbon emissions and mitigate globalized stressors, tropical coral reefs are in jeopardy. Strategic conservation and management requires identification of the environmental and socioeconomic factors driving the persistence of scleractinian coral assemblages—the foundation species of coral reef ecosystems. Here, we compiled coral abundance data from 2,584 Indo-Pacific reefs to evaluate the influence of 21 climate, social and environmental drivers on the ecology of reef coral assemblages. Higher abundances of framework-building corals were typically associated with: weaker thermal disturbances and longer intervals for potential recovery; slower human population growth; reduced access by human settlements and markets; and less nearby agriculture. We therefore propose a framework of three management strategies (protect, recover or transform) by considering: (1) if reefs were above or below a proposed threshold of >10% cover of the coral taxa important for structural complexity and carbonate production; and (2) reef exposure to severe thermal stress during the 2014–2017 global coral bleaching event. Our findings can guide urgent management efforts for coral reefs, by identifying key threats across multiple scales and strategic policy priorities that might sustain a network of functioning reefs in the Indo-Pacific to avoid ecosystem collapse

    What factors are associated with parental desire to find out the sex of their baby?

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    Respiratory rates of the Organ-Pipe Mud-Dauber Trypoxylon politum (Hymenoptera: Sphecoidea)

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    Oxygen consumption was determined at environmental temperatures throughout the life cycle of Trypoxy lon politum Say. Feeding larvae consumed a mean of 90.63 μ,l 02/ 100 mg body weight/ hour (bw/h) and declined to 48.98 in the fully fed stage. Early and late cocoon spinning stages consumed 41.18 and 20.62 μ,l/Oi lOO mg/h respectively. Oxygen consumption during diapause in prepupae, fell to 1.4 μ,l Oi lOO mg bw/h and essentially remained at that level from summer to the following spring. Propupae consumed 4.67 μ,l 02/ 100 mg bw/h and the pupal stages exhibited a progressive increase in oxygen consumption during development to a maximum of 29.79 μ,l 02/ 100 mg bw/h immediately before adult emergence. The adults consumed a mean of 197.26 μ,l Oi 100 mg bw/h. No difference in oxygen consumption due to sex of wasps was noted in pupal or adult stages. Log metabolism and metabolic rate vs. log body weight equations were calculated and the following slopes were determined: Larvae y = 283.6 X0· 0 and y/x = 285.8 x-0-38; prepupae y = 8.04 X0·73 and y/x = 7 . 75 x-0·3 1; pupae y = 46.2 X0·17 and y/x 42.2-0·89; and adults y = 1060 X0·74 and y/x = 1060 x-0·26. The coefficients of determination (r) indicate a good fit of the data to calculated slope values in larval stages, but decreased to near zero values in prepupae and pupal stages, and increased again in adults. We conclude that oxygen consumption in prepupal and pupal stages may be independent of body weight. The larval stage expend ca. 214 calories in respiratory energy reaching the prepupal stage (26.7% assimilated energy). The cost of overwintering maintenance is ca. 64 cal in the prepupal stage (8.0% assimilated energy), while the pupal stage requires ca. 166 cal (20.7% assimilated energy). These values compare favorably with calorimetrically determined energy budget for the wasp. The respiratory quotient determined for feeding larvae was 0.80 and all other stages had RQ\u27s of 0 .70. It appears that this wasp\u27s metabolic rate is influenced by daily and general temperature fluctuations
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