185,777 research outputs found
The vocalisations and anti-predatory behaviour of wild white-handed gibbons (Hylobates lar) in Khao Yai National Park, Thailand
No full textThe loud songs of gibbons (Hylobatidae) usually consist of a duet by the mated pair delivered each morning. These songs can transmit over a kilometre through dense forest habitat and therefore presumably play a role in long-distance communication. There is some evidence to suggest that gibbons use song in contexts other than their daily duets, such as predation, but these songs have not been well studied. Close- range communication is also relevant for gibbons, but these quieter calls have completely escaped any detailed observation.
The responses of wild white-handed gibbons (Hylobates lar) to simulated visual and acoustic predators (tiger, clouded leopard, reticulated python and crested serpent eagle) were studied in Khao Yai National Park, Thailand to address the lack of empirical data about these important events. Little is known about gibbons’ anti- predatory behaviour in general, and simulated predator encounters provided an opportunity to investigate these responses as well.
Results showed that gibbons used song as part of their anti-predator strategy and that subtle combinatorial changes were meaningful to conspecifics. They also showed marked behavioural changes in the short-term, and some evidence of longer-term changes as well. Quiet calls were also part of the gibbons’ response repertoire with the hoo call being particularly relevant. Hoos were used as a prelude to singing both normal duets and predator songs, but there were consistent differences between each context. Hoos were also delivered independently in a number of other contexts outside predation. When analysed, these hoos showed consistent contextual differences in a number of spectral parameters.
Within the duet context, important contextual subtleties were evident also revealing a remarkable vocal plasticity. In addition, gibbons voluntarily attended to specific vocal elements of other gibbon duets, indicating that certain sequences are more pertinent than others.
Results suggest both gibbon song and gibbon hoos are powerful communication tools that reliably reference external objects and events; this ability is also a critical feature of human language
Liste par Richard Gibbons des documents à l'appui des accusations contre G. R. Ainslie
No full text6 pages, originalListe [par Richard Gibbons] des documents à l'appui des accusations [contre G. R. Ainslie]
Hepatitis B virus in silvery gibbons (Hylobates moloch)
No full textThis research investigated a number of issues regarding hepatitis B virus (HBV) in the silvery gibbon (Hylobates moloch). Due to the relatively recent discovery of the virus in nonhuman primate populations, specific knowledge of the biological behaviour of the virus is presently lacking, with current information largely extrapolated from the behaviour of HBV in human infections. In order to manage the captive and wild populations of this critically endangered species, information regarding the behaviour of the virus in gibbons and the likely impact of the viral infection is essential.
The research was performed at Perth Zoo, with the study population consisting of the current and historical members of the zoo's silvery gibbon colony. Because this gibbon species is critically endangered, the study was conducted with minimal intervention to the population with samples collected largely on an opportunistic basis from a small study population.
Review of the history of the virus within the Perth Zoo colony provided epidemiological evidence to indicate vertical transmission in three gibbons (Hecla, Uban and Jury). It would appear that vertical transmission is the primary mode of transmission leading to dispersal of the virus through the captive population of silvery gibbons.
Elevated concentrations of the liver enzymes alanine aminotransferase and aspartate aminotransferase were found in three gibbons (Perth 2, Uban and Jury), and may suggest a pathogenic role of the virus in this species. Histological examination of the livers of Uban and Perth 2 failed to demonstrate definitive evidence of cirrhosis, however mild fibrosis was seen in both cases and may represent an early stage of liver pathology associated with chronic hepatitis B infection.
The vaccination protocol developed at Perth Zoo was successful in preventing neonatal transmission of the virus from a high infectivity carrier mother in at least two individuals, and was also successful in producing a protective level of immunity against the virus in all three of the individuals tested.
Sequencing of the complete hepatitis B genome from one gibbon (Hecla) revealed that she was infected with GiHV (Gibbon hepatitis B virus), an indigenous strain of HBV previously identified in a number of gibbon species, but not previously confirmed in the silvery gibbon. Hecla's strain of HBV was shown to be more closely related to other nonhuman primate strains of HBV than to any of the human strains of HBV. 100% nucleotide similarity to two of Hecla's siblings indicates that infection in all three animals was the result of vertical transmission from their mother. Partial sequencing of the virus from a second gibbon (Uban) identified another strain of GiHBV which supports the results of the epidemiological study. Neither gibbon showed a high sequence similarity to the virus sequenced from Ivan, the father of the third carrier gibbon (Jury), although only limited sequence data was available from Ivan. Consequently it is likely that at least three different strains of GiHBV are present within the silvery gibbon population.
The information contained in this thesis will assist in the understanding and management of hepatitis B infection in silvery gibbons, as well as the numerous other species of nonhuman primates now shown to be susceptible to this virus
Gibbons Hall, Catholic University, Brookland, D.C. - 1787
No full textNorth and west elevations of Gibbons Hall, Catholic University.Number in title was assigned by Willard Ros
Infinite-Centre Gibbons-Hawking Metrics, Applied to Gravitational Instantons and Monopoles
No full textWe investigate the convergence of infinite-centre Gibbons-Hawking metrics, in the contexts of four-dimensional gravitational instantons and their applications, Kaluza-Klein monopoles and vortices, gravitational calorons, analytical extensions of Majumdar-Papapetrou metrics to form extreme Reissner-Nordstrom black holes, and Kaluza-Klein black holes. We find that, in most cases, periodic arrangements of the sources give rise to divergent potentials. We investigate the consequences of various methods of ensuring convergence, particularly in terms of the appearance of naked singularities, and construct several new solutions of Einstein's equations
Procession, Cornerstone Laying, Gibbons Hall, October 12, 1911 - 2
No full textProcession of clerics and monks, led by a band, leaves McMahon Hall on its way to the Gibbons Hall cornerstone laying ceremony.Number in title was assigned by Willard Ros
Catholic University of America, Washington, D.C., going to lay the corner-stone of Gibbons Hall
No full textGroup of individuals, some in church vestments, makes their way from Catholic University's McMahon to attend the corner-stone laying of Gibbons Hall.This is an ink-printed halftone postcard, printed commerciall
Studies of foraminifera associated with gelidium pristoides (turner) keutzing (gelidiales: rhodophyta)
No full textDoctor EducationisOur understanding of the macrofauna of hard intertidal substrata around South
Africa is fairly comprehensive, and we have a good understanding of the environmental
factors responsible for structuring macrofaunal communities (McQuaid & Branch, 1985;
Bustamante et al., 1996; Emanuel et al., 1992). The same cannot be said for meiofaunal
communities of rocky shores, which despite their neglect are known to play an important
role in the functioning of many intertidal systems (Gibbons & Griffiths, 1986). While
macrofauna may dominate rocky shores in terms of biomass, meiofauna are generally
more abundant, and because they have faster turnover rates they make an important
contribution to secondary production (Gibbons & Griffiths, 1986)
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The syntax and meaning of wild gibbon songs
No full textSpoken language is a result of the human capacity to assemble simple vocal units into more complex utterances, the basic carriers of semantic information. Not much is known about the evolutionary origins of this behaviour. The vocal abilities of non-human primates are relatively unimpressive in comparison, with gibbon songs being a rare exception. These apes assemble a repertoire of call notes into elaborate songs, which function to repel conspecific intruders, advertise pair bonds, and attract mates. We conducted a series of field experiments with white-handed gibbons at Khao Yai National Park, Thailand, which showed that this ape species uses songs also to protect themselves against predation. We compared the acoustic structure of predatory-induced songs with regular songs that were given as part of their daily routine. Predator-induced songs were identical to normal songs in the call note repertoire, but we found consistent differences in how the notes were assembled into songs. The responses of out-of-sight receivers demonstrated that these syntactic differences were meaningful to conspecifics. Our study provides the first evidence of referential signalling in a free-ranging ape species, based on a communication system that utilises combinatorial rules.Peer reviewe
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