125,239 research outputs found
Traité Elémentaire Et Complet D'Ornithologie Ou Histoire Naturelle Des Oiseaux / Par F. M. Daudin, Membre des Sociétés d'Histoire Naturelle et Philomathique de Paris
No full textVorlageform der Veröffentlichungsangabe: A Paris, Chez L'Auteur, rue Hauteville, No. 27. Duprat, Libraire, quai des Augustins. De L'Imprimerie De Bertrandet
Cariotipo y región organizadora del núcleo en Teius teyou (Daudin, 1802) (Squamata: teiidae)
No full textSpecimens of Teius teyou (Daudin, 1982) from Formosa and Chaco, Argentina, were citologically analyzed. A karyotype characterized by 54 chromosomes and 2 pairs of ribosomal chromosomes were identified.Asociación Herpetológica Argentin
Surfactant effect of gallium during molecular beam epitaxy of GaN on AlN(0001)
No full textWe study the adsorption of Ga on (0001) GaN surfaces by reflection high-energy electron diffraction. It is shown that a dynamically stable Ga bilayer can be formed on the GaN surface for appropriate Ga fluxes and substrate temperatures. The influence of the presence of this Ga film on the growth mode of GaN on AlN(0001) by plasma-assisted molecular-beam epitaxy is studied. It is demonstrated that under nearly stoichiometric and N-rich conditions, the GaN layer relaxes elastically during the first stages of epitaxy. At high temperatures the growth follows a Stranski-Krastanov mode, whereas at lower temperatures kinetically formed flat platelets are observed. Under Ga-rich conditions-where a Ga bilayer is rapidly formed due to excess Ga accumulating on the surface-the growth follows a Frank-van der Merwe layer-by-layer mode at any growth temperature and no initial elastic relaxation occurs. Hence, it is concluded that excess Ga acts as a surfactant, effectively suppressing both Stranski-Krastanov islanding and platelet formation. It is further demonstrated that the Stranski-Krastanov transition is in competition with elastic relaxation by platelets, and it is only observed when relaxation by platelets is inefficient. As a result, a growth mode phase diagram is outlined for the growth of GaN on AlN(0001)
Agama aspera Daudin 1802
No full text<i>Agama aspera</i> Daudin, 1802 <p> <b>Holotype (by monotypy)</b>: MNHN-RA 0.2608 (2122); Ag 340 (also a syntype of <i>Agama spinosa</i> Dumeril & Bibron, 1837), without collector</p> <p> <b>Type locality</b>: Cap de Bonne Espérance (Cape of Good Hope, South Africa)</p> <p> <b>Nomeclatural status</b>: Senior homonym of <i>Agama aspera</i> Werner, 1893 and junior subjective synonym of <i>Agama hispida</i> (Linnaeus, 1758). The taxon name <i>Agama aspera</i> Daudin, 1802 is available for nomenclatural purposes.</p>Published as part of <i>Denzer, Wolfgang & Campbell, Patrick D., 2024, Nomenclatural notes on Agama spinosa Gray, 1831 and Agama aspera Daudin, 1802, pp. 391-395 in Zootaxa 5403 (3)</i> on page 394, DOI: 10.11646/zootaxa.5403.3.9, <a href="http://zenodo.org/record/10562080">http://zenodo.org/record/10562080</a>
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Site multiplicity of rare earth ions in III-nitrides
No full textThis presentation reviews recent lattice location studies of RE ions in GaN by electron emission channelling (EC) and X-ray absorption fine structure (XAFS) techniques. These studies agree that RE ions at low concentrations (whether they are incorporated during growth or introduced later by ion implantation) predominantly occupy Ga substitutional sites, as expected from considerations of charge equivalence. We combine this result with some examples of the welldocumented richness of optical spectra of GaN:RE3+ to suggest that the luminescence of these materials may be ascribed to a family of rather similar sites, all of which feature the REGa defect
Gallium adsorption on (0001) GaN surfaces
No full textWe study the adsorption behavior of Ga on (0001) GaN surfaces combining experimental specular reflection high-energy electron diffraction with theoretical investigations in the framework of a kinetic model for adsorption and ab initio calculations of energy parameters. Based on the experimental results we find that for substrate temperatures and Ga fluxes typically used in molecular-beam epitaxy of GaN, finite equilibrium Ga
surface coverages can be obtained. The measurement of a Ga/GaN adsorption isotherm allows the quantification
of the equilibrium Ga surface coverage as a function of the impinging Ga flux. In particular, we show that
a large range of Ga fluxes exists, where 2.5 +/- 0.2 monolayers (in terms of the GaN surface site density) of Ga are adsorbed on the GaN surface. We further demonstrate that the structure of this adsorbed Ga film is in good agreement with the laterally contracted Ga bilayer model predicted to be most stable for strongly Ga-rich surfaces [Northrup et al., Phys. Rev. B 61, 9932 (2000)]. For lower Ga fluxes, a discontinuous transition to Ga monolayer equilibrium coverage is found, followed by a continuous decrease towards zero coverage; for higher Ga fluxes, Ga droplet formation is found, similar to what has been observed during Ga-rich GaN growth. The
boundary fluxes limiting the region of 2.5 monolayers equilibrium Ga adsorption have been measured as a
function of the GaN substrate temperature giving rise to a Ga/GaN adsorption phase diagram. The temperature
dependence is discussed within an ab initio based growth model for adsorption taking into account the
nucleation of Ga clusters. This model consistently explains recent contradictory results of the activation energy describing the critical Ga flux for the onset of Ga droplet formation during Ga-rich GaN growth [Heying et al.,
J. Appl. Phys. 88, 1855 (2000); Adelmann et al., J. Appl. Phys. 91, 9638 (2002).]
Traité Elémentaire Et Complet D'Ornithologie Ou Histoire Naturelle Des Oiseaux
No full textVorlage des Erscheinungsvermerks: A Paris, Chez L'Auteur, rue Hauteville, No. 27. Duprat, Libraire, quai des Augustins. De L'Imprimerie De Bertrandet. 1800. - An VIII.8 Ill. (Kupferst., kolor.
Anolis auratus Daudin 1802
No full textAnolis auratus Daudin, 1802 Type-locality. Tropical America, restricted by Schmidt (1939) to Suriname. Pertinent taxonomic references. Daudin (1802 b), Wiegmann (1834), Duméril & Bibron (1837), Berthold (1840), Fitzinger (1843), Gray (1845), Hallowell (1856), O’Shaughnessy (1869 a, b), Peters (1869), Boulenger (1885, 1896), Schmidt (1939), Hoogmoed (1973), Savage & Guyer (1989), Ávila-Pires (1995), Kӧhler (2000), Poe (2004), Nicholson et al. (2012). Distribution and habitat. Anolis auratus occurs in southern Central America, in Panama and Nicaragua, and in northern South America, in Brazil, French Guiana, Suriname, Guyana, Venezuela, and Colombia (Fig. 1). In Brazil, it is known from the states of Amapá, Pará, Amazonas, and Roraima. Anolis auratus is predominantly terrestrial and diurnal. In Brazilian Amazonia it inhabits areas of open vegetation along the Amazon River, and natural and perianthropic enclaves of open vegetation in the states of Amapá and Roraima, where it is found on the ground, on grasses, low vegetation, shrubs, and on small trees (Cunha 1981 a; Vitt & Carvalho 1995; Mesquita et al. 2006 a).Published as part of Ribeiro-Júnior, Marco A., 2015, Catalogue of distribution of lizards (Reptilia: Squamata) from the Brazilian Amazonia. I. Dactyloidae, Hoplocercidae, Iguanidae, Leiosauridae, Polychrotidae, Tropiduridae, pp. 1-110 in Zootaxa 3983 (3) on page 5, DOI: 10.11646/zootaxa.3983.1.1, http://zenodo.org/record/23498
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