52 research outputs found
An overview of jets and outflows in stellar mass black holes
In this book chapter, we will briefly review the current empirical
understanding of the relation between accretion state and and outflows in
accreting stellar mass black holes. The focus will be on the empirical
connections between X-ray states and relativistic (`radio') jets, although we
are now also able to draw accretion disc winds into the picture in a systematic
way. We will furthermore consider the latest attempts to measure/order jet
power, and to compare it to other (potentially) measurable quantities, most
importantly black hole spin.Comment: Accepted for publication in Space Science Reviews. Also to appear in
the Space Sciences Series of ISSI - The Physics of Accretion on to Black
Holes (Springer Publisher
Towards an integrated set of surface meteorological observations for climate science and applications
Observations are the foundation for understanding the climate system. Yet, currently available land meteorological data are highly fractured into various global, regional and national holdings for different variables and timescales, from a variety of sources, and in a mixture of formats. Added to this, many data are still inaccessible for analysis and usage. To meet modern scientific and societal demands as well as emerging needs such as the provision of climate services, it is essential that we improve the management and curation of available land-based meteorological holdings. We need a comprehensive global set of data holdings, of known provenance, that is truly integrated both across Essential Climate Variables (ECVs) and across timescales to meet the broad range of stakeholder needs. These holdings must be easily discoverable, made available in accessible formats, and backed up by multi-tiered user support. The present paper provides a high level overview, based upon broad community input, of the steps that are required to bring about this integration. The significant challenge is to find a sustained means to realize this vision. This requires a long-term international program. The database that results will transform our collective ability to provide societally relevant research, analysis and predictions in many weather and climate related application areas across much of the globe
Colour polymorphism in birds: causes and functions
We studied polymorphism in all species of birds that are presently known to show intraspecific variation in plumage colour. At least three main mechanisms have been put forward to explain the maintenance of polymorphism: apostatic, disruptive and sexual selection. All of them make partly different predictions. Our aims were to investigate evolutionary causes and adaptive functions of colour polymorphism by taking into account a number of ecological and morphological features of polymorphic species. Overall, we found 334 species showing colour polymorphism, which is 3.5% of all bird species. The occurrence of colour polymorphism was very high in Strigiformes, Ciconiiformes, Cuculiformes and Galliformes. Phylogenetically corrected analysis using independent contrasts revealed that colour polymorphism was maximally expressed in species showing a daily activity rhythm extended to day/night, living in both open and closed habitats. All these findings support the hypothesis that colour polymorphism probably evolved under selective pressures linked to bird detectability as affected by variable light conditions during activity period. Thus, we conclude that selective agents may be prey, predators and competitors, and that colour polymorphism in birds may be maintained by disruptive selection
Birds
Background: The aim of this study was to investigate the presence of multidrug resistant yeasts in the faeces of synanthropic wild birds from the Bangsar suburb of Kuala Lumpur. Methods: Species characterisations of yeast isolates and determinations of antimycotic susceptibility profiles were undertaken using the commercial characterization kit, Integral System Yeasts Plus (Liofilchem, Italy). Results: Fourteen species of yeasts were detected in the bird faecal samples.Candida albicans was present in 28.89 % of bird faecal samples, Candida krusei (13.33%), Candida tropicalis (4.44%), Candida glabrata (4.44%), Candida parapsilosis (2.22%), Candida lambica (2.22%), Candida stellatoidea (2.22%), Candida rugosa (2.22%) and Candida lusitaniae (2.22%). Amongst the non-candidal yeast isolates, Cryptococcus laurentii was present in 6.67 % of bir
Divorce, dispersal and incest avoidance in the cooperatively breeding superb fairy-wren Malurus cyaneus
1. Between 1988 and 2001, we studied social relationships in the superb fairy-wren Malurus cyaneus (Latham), a cooperative breeder with male helpers in which extra-group fertilizations are more common than within-pair fertilizations. 2. Unlike other fairy-wren species, females never bred on their natal territory. First-year females dispersed either directly from their natal territory to a breeding vacancy or to a foreign 'staging-post' territory where they spent their first winter as a subordinate. Females dispersing to a foreign territory settled in larger groups. Females on foreign territories inherited the territory if the dominant female died, and were sometimes able to split the territory into two by pairing with a helper male. However, most dispersed again to obtain a vacancy. 3. Females dispersing from a staging post usually gained a neighbouring vacancy, but females gaining a vacancy directly from their natal territory travelled further, perhaps to avoid pairing or mating with related males. 4. Females frequently divorced their partner, although the majority of relationships were terminated by the death of one of the pair. If death did not intervene, one-third of pairings were terminated by female-initiated divorce within 1000 days. 5. Three divorce syndromes were recognized. First, females that failed to obtain a preferred territory moved to territories with more helpers. Secondly, females that became paired to their sons when their partner died usually divorced away from them. Thirdly, females that have been in a long relationship divorce once a son has gained the senior helper position. 6. Dispersal to avoid pairing with sons is consistent with incest avoidance. However, there may be two additional benefits. Mothers do not mate with their sons, so dispersal by the mother liberates her sons to compete for within-group matings. Further, divorcing once their son has become a breeder or a senior helper allows the female to start sons in a queue for dominance on another territory. Females that do not take this option face constraints on their ability to recruit more sons into the local neighbourhood
Small changes in timing of breeding among subarctic passerines over a 32-year period
Many bird populations in temperate regions have advanced their timing of breeding in response to a warming climate in recent decades. However, long-term trends in temperature differ geographically and between seasons, and so do responses of local breeding populations. Data on breeding bird phenology from subarctic and arctic passerine populations are scarce, and relatively little data has been recorded in open-nesting species. We investigated the timing of breeding and its relationship to spring temperature of 14 mainly open-nesting passerine species in subarctic Swedish Lapland over a period of 32 years (1984–2015). We estimated timing of breeding from the progress of post-juvenile moult in mist-netted birds, a new method exploring the fact that the progress of post-juvenile moult correlates with age. Although there was a numerical tendency for earlier breeding in most species (on average −0.09 days/year), changes were statistically significant in only three species (by −0.16 to −0.23 days/year). These figures are relatively low compared with what has been found in other long-term studies but are similar to a few other studies in subarctic areas. Generally, annual hatching dates were negatively correlated with mean temperature in May. This correlation was stronger in long-distance than in short-distance migrants. Although annual temperatures at high northern latitudes have increased over recent decades, there was no long-term increase in mean temperature in May over the study period at this subarctic site. This is probably the main reason why there were only small long-term changes in hatching dates
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