10,884 research outputs found
The Sun Asphericities: Astrophysical Relevance
Of all the fundamental parameters of the Sun (diameter, mass,
temperature...), the gravitational multipole moments (of degree l and order m)
that determine the solar moments of inertia, are still poorly known. However,
at the first order (l=2), the quadrupole moment is relevant to many
astrophysical applications. It indeed contributes to the relativistic
perihelion advance of planets, together with the post-Newtonian (PN)
parameters; or to the precession of the orbital plane about the Sun polar axis,
the latter being unaffected by the purely relativistic PN contribution. Hence,
a precise knowledge of the quadrupole moment is necessary for accurate orbit
determination, and alternatively, to obtain constraints on the PN parameters.
Moreover, the successive gravitational multipole moments have a physical
meaning: they describe deviations from a purely spherical mass distribution.
Thus, their precise determination gives indications on the solar internal
structure. Here, we explain why it is difficult to compute these parameters,
how to derive the best values, and how they will be determined in a near future
by means of space experiments.Comment: 14 pages, 9 figures (see published version for a better resolution),
submited to Proceedings of the Royal Society: Mathematical, Physical and
Engineering Science
Spin-Exchange Interaction in ZnO-based Quantum Wells
Wurtzitic ZnO/(Zn,Mg)O quantum wells grown along the (0001) direction permit
unprecedented tunability of the short-range spin exchange interaction. In the
context of large exciton binding energies and electron-hole exchange
interaction in ZnO, this tunability results from the competition between
quantum confinement and giant quantum confined Stark effect. By using
time-resolved photoluminescence we identify, for well widths under 3 nm, the
redistribution of oscillator strengths between the A and B excitonic
transitions, due to the enhancement of the exchange interaction. Conversely,
for wider wells, the redistribution is cancelled by the dominant effect of
internal electric fields, which dramatically reduce the exchange energy.Comment: 14 pages, 3 figure
Screening methods for age-related hearing loss in older patients with cancer: A review of the literature
© 2018 by the authors. As people grow older, they may experience loss in hearing sensitivity. Age-related hearing loss may negatively affect the patient's quality of life as it may lead to social isolation. In older patients with cancer, hearing loss can seriously interfere with the patient's ability to deal properly with all aspects of their disease, and may have a cumulative effect on their already decreased quality of life. Therefore, the proper screening of those conditions is essential in order to optimise the patient's comfort during and after treatment. This review article aims at providing a concise image of the nature of age-related hearing loss, and provides an overview of the screening methods that could be used in older patients with cancer
Repetition and difference: Lefebvre, Le Corbusier and modernity's (im)moral landscape: a commentary
This article engages with the relationship between social theory, architectural theory and material culture. The article is a reply to an article in a previous volume of the journal in question (Smith, M. (2001) âRepetition and difference: Lefebvre, Le Corbusier and modernityâs (im)moral landscapeâ, Ethics, Place and Environment, 4(1), 31-34) and, consequently, is also a direct engagement with another academic's scholarship. It represents a critique of their work as well as a recasting of their ideas, arguing that the matter in question went beyond interpretative issues to a direct critique of another author's scholarship on both Le Corbusier and Lefebvre. A reply to my article from the author of the original article was carried in a later issue of the journal (Smith, M. (2002) âEthical Difference(s): a Response to Maycroft on Le Corbusier and Lefebvreâ, Ethics, Place and Environment, 5(3), 260-269)
Incommensurate Mott Insulator in One-Dimensional Electron Systems close to Quarter Filling
A possibility of a metal-insulator transition in molecular conductors has
been studied for systems composed of donor molecules and fully ionized anions
with an incommensurate ratio close to 2:1 based on a one-dimensional extended
Hubbard model, where the donor carriers are slightly deviated from quarter
filling and under an incommensurate periodic potential from the anions. By use
of the renormalization group method, interplay between commensurability energy
on the donor lattice and that from the anion potential has been studied and it
has been found that an "incommensurate Mott insulator" can be generated. This
theoretical finding will explain the metal-insulator transition observed in
(MDT-TS)(AuI).Comment: 4 pages, 4 figures, submitted to J. Phys. Soc. Jpn. at December 24
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A Study on Electro-Osmotic Consolidation of Soft Clays
The effects of an electro-osmotic treatment on a soft sensitive clay from Eastern Canada were examined based on the laboratory tests performed on undisturbed specimens. The interpretation of the tests focus on the non-homogeneity of the treatment, the influence of polarity reversal and strong induration which develops near the anode in addition to the consolidation
Habitatâdependent occupancy and movement in a migrant songbird highlights the importance of mangroves and forested lagoons in Panama and Colombia
Climate change is predicted to impact tropical mangrove forests due to decreased rainfall, seaâlevel rise, and increased seasonality of flooding. Such changes are likely to influence habitat quality for migratory songbirds occupying mangrove wetlands during the tropical dry season. Overwintering habitat quality is known to be associated with fitness in migratory songbirds, yet studies have focused primarily on territorial species. Little is known about the ecology of nonterritorial species that may display more complex movement patterns within and among habitats of differing quality. In this study, we assess withinâseason survival and movement at two spatioâtemporal scales of a nonterritorial overwintering bird, the prothonotary warbler (Protonotaria citrea), that depends on mangroves and tropical lowland forests. Specifically, we (a) estimated withinâpatch survival and persistence over a sixâweek period using radioâtagged birds in central Panama and (b) modeled abundance and occupancy dynamics at survey points throughout eastern Panama and northern Colombia as the dry season progressed. We found that site persistence was highest in mangroves; however, the probability of survival did not differ among habitats. The probability of warbler occupancy increased with canopy cover, and wet habitats were least likely to experience local extinction as the dry season progressed. We also found that warbler abundance is highest in forests with the tallest canopies. This study is one of the first to demonstrate habitatâdependent occupancy and movement in a nonterritorial overwintering migrant songbird, and our findings highlight the need to conserve intact, mature mangrove, and lowland forests
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