211,026 research outputs found
Analysis of two genomic variants of orang-utan hepadnavirus and their relationship to other primate hepatitis B-like viruses
No full textWe recently described orang-utan hepadnavirus (OuHV) (Warren et al., Journal of Virology, 73, 7860–7865, 1999). Phylogenetic analyses indicated that the various isolates of OuHV can be divided into two genomic variants. Two representatives from each genomic cluster were analysed both molecularly and phylogenetically. Their genome organization was highly similar to other hepadnaviruses of apes and humans. The complete genome sequences of the two OuHV types had an overall 5% sequence difference. Research on 25 seropositive Bornean orang-utans showed that, of the 19 animals infected with one variant, 12 originated from East Kalimantan. Phylogenetic analysis was performed using the full-length genomes of various primate hepadnaviruses. The tree topology revealed one cluster of Old World hepadnaviruses that is divided into two subclusters, one consisting of the ape viruses, and the other comprising the human genotypes A–E. These data suggest that the great apes and gibbons have been infected with a common ancestor hepadnavirus
A field study on Sumatran orang utans (Pongo pygmaeus abelii Lesson 1827) : ecology, behaviour and conservation
No full textThe results of a three year research project on the ecology, behaviour and conservation of the Sumatran orang utan are discussed. The 150 hectares Ketambe study area lie within the boundaries of the Gunung Leuser. reserve in Aceh Tenggara, and consists of mixed rainforest typical of hilly regions.The orang utan's food is irregularly distributed in quantity, space and time within this area. Although the orang utan is frugivorous he also eats leaves, insects, 'bark' and several other less important foods, such as bird's eggs. By far the largest part of the 114 food plants collected is typical primary rainforest growth. Figs make up an important part of the diet, particularly those known as the 'strangling' Ficus spp. As the fruiting seasons of the various strangling fig species are staggered over the whole year, and such trees are often enormous in size, they form particularly suitable food sources. Orang utans appear to have a good topographical knowledge of their 'home range'. There are indications that fig trees bearing ripe fruits are sometimes found by using the flight paths of flocks of hornbills, which also feed on figs. With respect to figs in particular, the orang utan must compete for its food with many other species, notably primates.The study area was regularly used by 22 individually recognized orang utans. Both males and females live in homeranges which overlap considerably and are 2-10 km sq. in extent. The population density of the Ketambe area is considerably higher than that reported for other areas in Indonesia, being approximately 5 individuals per square kilometre. Orang utans live a 'limited gregarious' lifestyle, that is, adult males spend the largest part of their time alone, and avoid encounters with other adult males. The adult females and their offspring stay together for the first 4-5 years of life (the birth interval is at least 3 years.). Adolescent social groups form after the mother-offspring bond becomes weaker. This social phase continues for each individual until either (a) the sexual dimorphistic characteristics of males are clearly distinguishable (at approximately 15 years of age), or (b) the female's first young is born (approximately 10 years of age). Adults also have social moments in their lives. Several individuals in an area can come together to form a 'temporary association' in certain fruit trees. It may be seen from their behaviour that they know each other well and that a network of relationships exist which is partly based on competitive dominance. A peaceful co-existence between adult males however, has not been observed; meetings between adult males had invariably an agonistic character. The sexual behaviour of the orang utan is roughly divisable into: (a) 'raping' of some females by sub-adult males; and (b) cooperative matings, where females often take the intitiative by presenting themselves to, usually, adult males. It appears that only the latter makes an essential contribution to reproduction.The social behaviour of the orang utan is considered and described in detail. Comparison of the behavioural repertoire of this species with that of the (gregarious) chimpanzee shows that the two species are closely related. There are clear differences in social organisation, however, which appear to be mainly of degree, rather than of quality. The social organisation of an animal must be a factor that fits its situational (i.e. environmental) context, but is based on phylogenetic characteristics. Comparison of the habitats of these two apes reveals that they both live in a similar ecological condition with respect to food. The reasons for the exceptional life-style on the part of the orang utan are possibly to be found in the predation pressure the species is exposed to, particularly by man. Man has been present in regions of South-EastAsia since the Pleistocene. It is plausible that the orang utan has been persecuted by man continuously from this time. A comparable influence on the chimpanzee is much more recent. The orang utan is the heaviest arboreal creature and has an exceptional social organisation for a primate. If it may be assumed that high intelligence is a biological outcome of complex group life then, on grounds of intelligence, and from the distinct social organisation and current arboreal life-style it maybe postulated that the orang utan has evolved from a groundliving social ape. This original form was supplanted from its niche by a better adapted ground-living social ape, that is, man. It is possible that a stricly arboreal life style for an animal as heavy as an adult orang utan is not compatible with a social life-style. Moreover, it is likely that refraining from a high degree of sociability and inconspicuousness are the best strategies against human predation.Since one possibility is that the hunting pressure in ancient (and current) times had a great influence on the biology of the orang utan, I have paid particular attention to hunting behaviour in hominids. At present, this form of threat is overshadowed by excessive habitat destruction. Cultivation in connection with the explosive population growth in Indonesia, together with the commercial timber concerns, affect the tropical rainforest ecosystem in such proportions that even reserves are threatened. Despite being protected since 1932, the orang utan is a severely endangered species. Rehabilitation of orang utans is a conservation action directed at reducing the still ongoing hunting pressure. This is despite the fact that there are clear risks in this to the wild population. These risks can be negated by confining rehabilitation projects to areas lacking a wild orang utan population.The orang utan is a component of an intact ecosystem and it is of utmost importance that the emphasis of nature conservation schemes is placed on the totality and balance of the tropical rainforest ecosystem. Every form of commercial exploitation within this ecosystem is incompatible with the proposed goal of preserving the system. The removal of components (e.g. 'selective logging' or 'selective hunting') does real damage to the balance of the system.An orang utan who lives in an exploited forest is in principle of equally small biological value as an orang utan in a zoo; it is a, debatably essential, biological solution that does not correspond to the set of conditions originally operating in its natural selection
Anticipated climate and land-cover changes reveal refuge areas for Borneo's orang-utans
No full textHabitat loss and climate change pose a double jeopardy for many threatened taxa, making the identification of optimal
habitat for the future a conservation priority. Using a case study of the endangered Bornean orang-utan, we identify
environmental refuges by integrating bioclimatic models with projected deforestation and oil-palm agriculture
suitability from the 1950s to 2080s. We coupled a maximum entropy algorithm with information on habitat needs to
predict suitable habitat for the present day and 1950s. We then projected to the 2020s, 2050s and 2080s in models
incorporating only land-cover change, climate change or both processes combined. For future climate, we incorporated
projections from four model and emission scenario combinations. For future land cover, we developed spatial
deforestation predictions from 10 years of satellite data. Refuges were delineated as suitable forested habitats identified
by all models that were also unsuitable for oil palm – a major threat to tropical biodiversity. Our analyses indicate
that in 2010 up to 260 000 km2 of Borneo was suitable habitat within the core orang-utan range; an 18–24%
reduction since the 1950s. Land-cover models predicted further decline of 15–30% by the 2080s. Although habitat
extent under future climate conditions varied among projections, there was majority consensus, particularly in northeastern
and western regions. Across projections habitat loss due to climate change alone averaged 63% by 2080, but
74% when also considering land-cover change. Refuge areas amounted to 2000–42 000 km2 depending on thresholds
used, with 900–17 000 km2 outside the current species range. We demonstrate that efforts to halt deforestation could
mediate some orang-utan habitat loss, but further decline of the most suitable areas is to be expected given projected
changes to climate. Protected refuge areas could therefore become increasingly important for ongoing translocation
efforts. We present an approach to help identify such areas for highly threatened species given environmental
changes expected this century
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Money, magic and fear : identity and exchange amongst the Orang Suku Laut (sea nomads) and other groups of Riau and Batam, Indonesia.
No full textThe central focus of my thesis is the symbolism of money and the power it
holds in the Riau archipelago and Batam of Indonesia to affect the nature of
social relationships. These social relationships in turn affect the different
forms of exchange that take place in the archipelago.
In particular, I am exploring the meaning and moral implications of
monetary and commercial exchanges in contrast to exchanges of other kinds
that take place between the Orang Suku Laut and other Malay and non-Malay
communities. The Orang Suku Laut are regarded as the Orang asli Melayu
(indigenous Malays) of Riau. Yet in the interaction between the Malays and
Orang Suku Laut, there exists much fear between them with constant
accusations of being poisoned and harmed by one and the other through
practices of magic and witchcraft. This stems from the Malays' perception of
the Orang Suku Laut as a "dangerous, dirty and unprogressive people. "
The Orang Suku Laut are regarded as preferring a life of nomadism,
and one without a religious orientation towards Islam, as opposed to a life of
sedentism guided by the Islamic religion. This thesis explores how this self
and other perceptions which have shaped the image of the Orang Suku Laut,
have become enmeshed in the exchange economy of the Orang Suku Laut and
the Malays
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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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
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