Results 81 to 90 of about 19,174 (307)
American Journal of Botany, EarlyView.Abstract Premise The identity of sterile floral organs in second‐whorl, alternisepalous positions within Caryophyllaceae remains contentious, having been described as staminodes, “petaloids,” or petals homologous with those of other Pentapetalae. Limited ingroup and outgroup sampling and floral developmental data and inadequate phylogenetic comparative
Riley J. Rees +2 more
wiley +1 more source
Comets, interstellar clouds and star clusters [PDF]
, 1976 The association of comets with star formation in clusters is elaborated. This hypothesis is also used to explain origin and evaluation of the Oort cloud, the composition of comets, and relationships between cometary and interstellar ...
Donn, B.
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Hunting and Imaging Comets [PDF]
, 2011 Of all the objects visible in the night sky, it is the brightest comets that have most fascinated amateur astronomers and alarmed the human population. No other objects can stretch as far across the sky as the tail of a truly great comet, or be as easily
Martin Mobberley, Mobberley, Martin
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Thermal Evolution of the Nucleus of the Comet 67P for 120 Years: Numerical Simulations
Open Astronomy, 2018 The purpose of this paper is to estimate to what temperatures and to what depth the outer layers of the cometary nuclei are heated for several dozen revolutions around the Sun, and what changes in the composition of the volatiles occur in this case. This
Rusol Andrey V., Dorofeeva Vera A.
doaj +1 more source
Skeletal pathologies in extant crocodilians as a window into the paleopathology of fossil archosaurs
The Anatomical Record, EarlyView.Abstract Crocodilians, together with birds, are the only extant relatives to many extinct archosaur groups, making them highly important for interpreting paleopathological conditions in a phylogenetic disease bracketing model. Despite this, comprehensive data on osteopathologies in crocodilians remain scarce.
Alexis Cornille +6 more
wiley +1 more source
On observing comets for nuclear rotation [PDF]
, 1981 The prevalent non-gravitational motions among comets demonstrate that the sublimination does not reach a maximum at the instant of maximum insolation on the nucleus. The occurrence of halos or "parabolic" envelopes in the comae of some comets and of jets,
Whipple, F. L.
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Photoluminescence and Cathodoluminescence of the Solid Cometary Substance
Open Astronomy, 2019 We have proposed that solar ultraviolet and corpuscular radiations may excite photoluminescence and cathodoluminescence of the solid cometary substance including mineral halos of comets.
Simonia Irakli, Gucsik Arnold
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The Anatomical Record, EarlyView.Abstract The vertebrate skull is composed of bones derived from neural crest cells and mesoderm. The evolutionary capacity of the skull has been linked, in part, to the emergence of neural crest cells; however, this increased capacity for evolutionary change requires that variation within neural crest‐ and mesoderm‐derived bones remains partly ...
Alyssa C. Moore +5 more
wiley +1 more source
Activity in distant comets [PDF]
, 1992 Activity in distant comets remains a mystery in the sense that we still have no complete theory to explain the various types of activity exhibited by different comets at large distances.
Luu, Jane X.
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“Stars Falling to Earth”—Mental Models of Comets and Meteors
Education SciencesThe present study examines students’ conceptions of comets and meteors using qualitative research methods. A total of 35 semi-structured interviews were conducted with students in grades 7 and 9 in Germany, aiming to gain a richer understanding of how ...
Malte S. Ubben +2 more
doaj +1 more source