63 research outputs found
Supernovae and the origin of cosmic rays
This thesis contains a review of our present knowledge about the cosmic ray flux and about supernovae and their-remnants. It contains an attempt to examine the widely- held belief" that cosmic rays are produced principally in supernova remnants by work on essentially four topics' connected with the production of cosmic rays in supernova- remnants;-a) The likely surface density of supernova remnants in the Galaxy as a function of distance from the Galactic centre. It is shown that the general shape of the surface density curve consists of a large peak near the Galactic centre followed by a fairly, rapid fall to a low value at the edge of the Galaxy. The actual values of surface density are very dependent on the distances of the observed supernova remnants, which in turn depend on the adopted surface brightness - diameter relationship, b) The predicted slope of the electron spectrum between energies of 4x10(^8) and 10(^10) eV, assuming it results from the addition of the energy spectra of all the supernova remnants in the Galaxy. The observed electron energy spectrum in this range is at present too uncertain to be able to say whether or not it disagrees with that predicted. c) The time of production of cosmic rays in supernova remnants, if they are to traverse no more matter than that which is inferred from the ratio of abundances of the L to M groups in the cosmic rays. It is found that if the cosmic rays are produced inside the expanding remnant, then the matter traversal constraint means that they must be produced 2 years or so after the explosion. d) The expected distribution of gamma rays in the Galaxy from supernova remnants of diameters less than 50 parsecs. It is shown that in all probability the gamma ray results give direct evidence of the presence of cosmic rays in supernova remnants but that supernova remnants alone cannot be responsible for the whole of the gamma ray flux, at least on present gamma ray production models
Trapping, collaring and monitoring the Lorisinae of Asia (Loris, Nycticebus) and Perodicticinae (Arctocebus, Perodicticus) of Africa
Nocturnal animals are difficult to see and follow, especially in dense rainforest conditions. Nocturnal research is fraught with difficulties not encountered by individuals who study animals in the day, from the need for expensive equipment, constant access to power supplies to run lights and potential for increased encounters with dangerous wildlife. The main drawback of nocturnal fieldwork is that it is simply more difficult to find and continuously observe an animal at night. Through hard work and perseverance it is possible to obtain ecological data on lorises and pottos in the absence of radio tracking (e.g. Das et al., 2014; Nekaris, 2001; Pliosungnoen et al., 2010). Much more detail can be obtained, however, through capturing, measuring, collaring and monitoring nocturnal primates. The essential nature of radio tracking for the study of the behaviour and ecology of nocturnal primates has been recognised since the 1970s (e.g. Charles-Dominique, 1977a; Charles-Dominique and Bearder, 1979), and is by most researchers considered a must for thorough research (Sterling et al., 2000). Radio-tracking studies of lorises and pottos remain limited (2000; Millspaugh and Marzluff, 2001). In this chapter, we review the methods for trapping and collaring slow lorises and pottos, as well as provide a case study of the importance of red light for observing their behaviour in a humane and productive manner
Sleep patterns, daytime predation, and the evolution of diurnal sleep site selection in lorisiforms.
Synthesize information on sleep patterns, sleep site use, and daytime predation at sleep sites in lorisiforms of Asia and Africa (10 genera, 36 species), and infer patterns of evolution of sleep site selection. We conducted fieldwork in 12 African and six Asian countries, collecting data on sleep sites, timing of sleep and predation during daytime. We obtained additional information from literature and through correspondence. Using a phylogenetic approach, we established ancestral states of sleep site selection in lorisiforms and traced their evolution. The ancestral lorisiform was a fur-clinger and used dense tangles and branches/forks as sleep sites. Use of tree holes and nests as sleep sites emerged ∼22 Mya (range 17-26 Mya) in Africa, and use of bamboo emerged ∼11 (7-14) Mya in Asia and later in Africa. Fur clinging and some sleep sites (e.g., tree holes, nests, but not bamboo or dense tangles) show strong phylogenetic signal. Nests are used by Galagoides, Paragalago, Galago and Otolemur; tree holes by Galago, Paragalago, Sciurocheirus and Perodicticus; tangles by Nycticebus, Loris, Galagoides, Galago, Euoticus, Otolemur, Perodicticus and Arctocebus; all but Sciurocheirus and Otolemur additionally sleep on branches/forks. Daytime predation may affect sleep site selection and sleep patterns in some species of Nycticebus, Galago, Galagoides, Otolemur and Perodicticus. Most lorisiforms enter their sleep sites around sunrise and leave around sunset; several are active during twilight or, briefly, during daytime. Variations in sleep behavior, sleep patterns and vulnerability to daytime predation provide a window into the variation that was present in sleep in early primates. Overall, lorisiforms use the daytime for sleeping and no species can be classified as cathemeral or polycyclic
Remarkable Ancient Divergences Amongst Neglected Lorisiform Primates
Lorisiform primates (Primates: Strepsirrhini: Lorisiformes) represent almost 10% of the living primate species and are widely distributed in sub-Saharan Africa and South/South-East Asia; however, their taxonomy, evolutionary history, and biogeography are still poorly understood. In this study we report the largest molecular phylogeny in terms of the number of represented taxa. We sequenced the complete mitochondrial cytochrome b gene for 86 lorisiform specimens, including ∼80% of all the species currently recognized. Our results support the monophyly of the Galagidae, but a common ancestry of the Lorisinae and Perodicticinae (family Lorisidae) was not recovered. These three lineages have early origins, with the Galagidae and the Lorisinae diverging in the Oligocene at about 30 Mya and the Perodicticinae emerging in the early Miocene. Our mitochondrial phylogeny agrees with recent studies based on nuclear data, and supports Euoticus as the oldest galagid lineage and the polyphyletic status of Galagoides. Moreover, we have elucidated phylogenetic relationships for several species never included before in a molecular phylogeny. The results obtained in this study suggest that lorisiform diversity remains substantially underestimated and that previously unnoticed cryptic diversity might be present within many lineages, thus urgently requiring a comprehensive taxonomic revision of this primate group
The mammals of Angola
Scientific investigations on the mammals of Angola started over 150 years
ago, but information remains scarce and scattered, with only one recent published
account. Here we provide a synthesis of the mammals of Angola based on a thorough
survey of primary and grey literature, as well as recent unpublished records. We present
a short history of mammal research, and provide brief information on each species
known to occur in the country. Particular attention is given to endemic and near endemic
species. We also provide a zoogeographic outline and information on the conservation
of Angolan mammals. We found confirmed records for 291 native species, most of
which from the orders Rodentia (85), Chiroptera (73), Carnivora (39), and
Cetartiodactyla (33). There is a large number of endemic and near endemic species,
most of which are rodents or bats. The large diversity of species is favoured by the wide range of habitats with contrasting environmental conditions, while endemism tends to
be associated with unique physiographic settings such as the Angolan Escarpment. The
mammal fauna of Angola includes 2 Critically Endangered, 2 Endangered, 11
Vulnerable, and 14 Near-Threatened species at the global scale. There are also 12 data
deficient species, most of which are endemics or near endemics to the countryinfo:eu-repo/semantics/publishedVersio
A giant among dwarfs: a new species of galago (Primates: Galagidae) from Angola
Objectives: Based on vocalization recordings of an unknown galago species, our main objectives were to compare morphology and call structure with known closely-related taxa and describe a new species of galago.
Materials and Methods: We conducted field surveys in three forest habitats along the
escarpment region in western Angola (Kumbira Forest, Bimbe Area and Northern Scarp Forest), and examined galago specimens from museums worldwide. We digitized and analyzed calls using Avisoft SASLab Pro software. We also compared museum specimens from Angola with other Galago and Galagoides specimens, and conducted comparative analyses (ANOVA and between group principle component analysis) based on a set of twelve linear measurements of skulls and teeth.
Results: We describe the new species to which we give the name Angolan dwarf galago, Galagoides kumbirensis sp. nov. The new species has a loud and characteristic crescendo call, used by other Galagoides spp. (sensu stricto) in West Africa to attract companions and repel rivals. However, this call shows species-typical differences from its closest relatives. Galagoides kumbirensis sp. nov. is also distinguished by differences in the skull morphology, pelage color and facial markings, as well as a larger body size, similar to that of Galago moholi, which is not known to be sympatric.
Conclusion: This discovery points to the importance of Angolan forests as refuges for endemic biodiversity. These forests are under severe threat from over-exploitation, and there is an urgent need to establish conservation measures and designate protected areas
Defining the Low End of Primate Social Complexity: The Social Organization of the Nocturnal White-Footed Sportive Lemur (Lepilemur leucopus)
Estudi de les causes de la mortalitat del cultiu de mongeters a l'hivernacle del campus del Baix Llobregat
L’equip de Millora Genètica de l’ESAB juntament amb SERIDA (Servicio Regional de
Investigación y Desarrollo Agroalimentario de Asturias) porta un programa d’introducció de gens de resistència assistit per marcadors genètics, en Mongeta del Ganxet (L67), en el què es pretenen aconseguir resistències a l’antracnosi (Colletotrichum lindemuthianun) i al BMV o virus del mosaic.
A l’hivernacle del Campus del Baix Llobregat, la majoria dels intents del cultiu les plantes naixien bé però, en arribar a la floració, moltes plantes començaven a mostrar símptomes d’assecament i col·lapse de les fulles i la majoria morien abans que les tavelles arribessin a madurar. En aquests intents es van perdre algunes línies d’encreuaments i, per
tant, abans de perdre tot el material es va decidir que era prioritari esbrinar les causes de la mort de les plantes al hivernacle.
El disseny experimental ha consistit en cultivar les mongeteres estudiant quatre factors diferents: la localitat, el substrat, l’aigua de reg i els tractaments fungicides.
L’excés de salinitat de l’aigua de Castelldefels fa reduir el vigor general de les plantes, endarrereix la floració i, sobre tot, redueix la producció degut a l’elevada mortalitat en les plantes.
Per al cultiu en hivernacle, cal disposar-ne d’un en condicions, ben emplaçat i amb un
mínim control de temperatura i ventilació.
Habitualment, el substrat Compo 100% dóna resultats significativament superiors que
els substrats Compo-Perlita, que es troba en segon lloc, i Compo-Sorra, que dóna els pitjors resultats.
La millor combinació per tenir plantes sanes i que arribin al final del cicle seria, per
ordre d’importància, aigua amb baix contingut en sals, substrat Compo 100%, un hivernacle adequat i un tractament preventiu fungicida espaiat en el temps fins la floració
Cyclic AMP and calcium mediate the regulation of fat cell activity by octopamine and peptide hormones in Glossina morsitans
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