7,053 research outputs found
Much more than just sediments: The importance of sediment composition for Great Barrier Reef ecosystems
We can now identify the most damaging properties of sediment, associated particulate nutrients and its effects on ecological communities as it moves from catchment to reef. It is the fine grained (colloidal, clay and fine silts <20 μm), organic-rich sediment that has a critical impact on marine ecosystems through both direct effects (i.e. smothering) and increased reduction of benthic light relative to sediments produced in the marine environment. Marine sediments are commonly lighter in colour, carbonate-rich and mostly (but not always) coarser compared with land-sourced sediments. An improved understanding of the influence (including potential impacts) of sediment on GBR ecosystems and the ‘sea to source’ connections and interactions is required to guide management responses that reduce sediment delivery to the GBR
Multirelational Organization of Large-scale Social Networks in an Online World
The capacity to collect fingerprints of individuals in online media has
revolutionized the way researchers explore human society. Social systems can be
seen as a non-linear superposition of a multitude of complex social networks,
where nodes represent individuals and links capture a variety of different
social relations. Much emphasis has been put on the network topology of social
interactions, however, the multi-dimensional nature of these interactions has
largely been ignored in empirical studies, mostly because of lack of data.
Here, for the first time, we analyze a complete, multi-relational, large social
network of a society consisting of the 300,000 odd players of a massive
multiplayer online game. We extract networks of six different types of
one-to-one interactions between the players. Three of them carry a positive
connotation (friendship, communication, trade), three a negative (enmity, armed
aggression, punishment). We first analyze these types of networks as separate
entities and find that negative interactions differ from positive interactions
by their lower reciprocity, weaker clustering and fatter-tail degree
distribution. We then proceed to explore how the inter-dependence of different
network types determines the organization of the social system. In particular
we study correlations and overlap between different types of links and
demonstrate the tendency of individuals to play different roles in different
networks. As a demonstration of the power of the approach we present the first
empirical large-scale verification of the long-standing structural balance
theory, by focusing on the specific multiplex network of friendship and enmity
relations.Comment: 7 pages, 5 figures, accepted for publication in PNA
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To be or not to be an auctioneer: Some thoughts on the legal nature of online eBay auctions and the protection of consumers
This paper discusses the legal classification of online “eBay” auctions. The discussion has key implications on the scope of consumer protection law as sale by auctions are, for example, excluded from the scope of the Consumer Protection (Distance Selling) Regulations 2000. The paper uncovers that online “eBay” auctions cannot always be considered as traditional auctions and that eBay, as an intermediary, is not to be considered as an auctioneer. This creates difficulties associated with a distributive application of consumer protection laws such as the Consumer Protection (Distance Selling) Regulations 2000. Another set of difficulties is associated with a lenient legal regime applicable to the liability of eBay under the Electronic Commerce (EC Directive) Regulations 2002 . The paper concludes that there is an urgent need to clarify the legal classification of online auctions and to rethink the liability of online auction sites to better protect consumers
Longitudinal measurement of the developing grey matter in preterm subjects using multi-modal MRI.
Preterm birth is a major public health concern, with the severity and occurrence of adverse outcome increasing with earlier delivery. Being born preterm disrupts a time of rapid brain development: in addition to volumetric growth, the cortex folds, myelination is occurring and there are changes on the cellular level. These neurological events have been imaged non-invasively using diffusion-weighted (DW) MRI. In this population, there has been a focus on examining diffusion in the white matter, but the grey matter is also critically important for neurological health. We acquired multi-shell high-resolution diffusion data on 12 infants born at ≤28weeks of gestational age at two time-points: once when stable after birth, and again at term-equivalent age. We used the Neurite Orientation Dispersion and Density Imaging model (NODDI) (Zhang et al., 2012) to analyse the changes in the cerebral cortex and the thalamus, both grey matter regions. We showed region-dependent changes in NODDI parameters over the preterm period, highlighting underlying changes specific to the microstructure. This work is the first time that NODDI parameters have been evaluated in both the cortical and the thalamic grey matter as a function of age in preterm infants, offering a unique insight into neuro-development in this at-risk population
The role of zoos in attitudes towards biodiversity and the reintroduction of native wild carnivores to the UK: results from a pilot study
This paper presents preliminary findings from a pilot study involving focus groups and semi-structured interviews with members of the public at three locations in Kent, UK. The pilot study aims to inform a large scale baseline survey of attitudes, beliefs and values towards biodiversity, the focus species (lynx and Pine Marten) and their conservation and reintroduction in the UK
Curvature-induced stiffening of a fish fin
How fish modulate their fin stiffness during locomotive manoeuvres remains
unknown. We show that changing the fin's curvature modulates its stiffness.
Modelling the fin as bendable bony rays held together by a membrane, we deduce
that fin curvature is manifested as a misalignment of the principal bending
axes between neighbouring rays. An external force causes neighbouring rays to
bend and splay apart, and thus stretches the membrane. This coupling between
bending the rays and stretching the membrane underlies the increase in
stiffness. Using analysis of a 3D reconstruction of a Mackerel (Scomber
japonicus) pectoral fin, we calculate the range of stiffnesses this fin is
expected to span by changing curvature. The 3D reconstruction shows that, even
in its geometrically flat state, a functional curvature is embedded within the
fin microstructure owing to the morphology of individual rays. Since the
ability of a propulsive surface to transmit force to the surrounding fluid is
limited by its stiffness, the fin curvature controls the coupling between the
fish and its surrounding fluid. Thereby, our results provide mechanical
underpinnings and morphological predictions for the hypothesis that the spanned
range of fin stiffnesses correlates with the behaviour and the ecological niche
of the fish
Ecologically relevant targets for pollutant discharge from the drainage basins of the Fitzroy Region, Great Barrier Reef
[Extract] Ecologically relevant targets (ERTs) attempt to define the pollutant load reductions that would be required to meet the Great Barrier Reef (GBR) Water Quality Guidelines, which are set at a standard considered to be suitable to maintain ecosystem health. Thus ERTs are required to be met to achieve the overall long-term Reef Plan goal “To ensure that by 2020 the quality of water entering the reef from broadscale land use has no detrimental effect on the reef’s health and resilience”....The methods for deriving the ERTs vary between the pollutants. These are summarised....and described in detail in the body of this report
A far-UV survey of three hot, metal-polluted white dwarf stars: WD0455-282, WD0621-376, and WD2211-495
Using newly obtained high-resolution data () from the
\textit{Hubble Space Telescope}, and archival UV data from the \textit{Far
Ultraviolet Spectroscopic Explorer} we have conducted a detailed UV survey of
the three hot, metal-polluted white dwarfs WD0455-282, WD0621-376, and
WD2211-495. Using bespoke model atmospheres we measured , log
, and photospheric abundances for these stars. In conjunction with data from
Gaia we measured masses, radii, and gravitational redshift velocities for our
sample of objects. We compared the measured photospheric abundances with those
predicted by radiative levitation theory, and found that the observed Si
abundances in all three white dwarfs, and the observed Fe abundances in
WD0621-376 and WD2211-495, were larger than those predicted by an order of
magnitude. These findings imply not only an external origin for the metals, but
also ongoing accretion, as the metals not supported by radiative levitation
would sink on extremely short timescales. We measured the radial velocities of
several absorption features along the line of sight to the three objects in our
sample, allowing us to determine the velocities of the photospheric and
interstellar components along the line of sight for each star. Interestingly,
we made detections of circumstellar absorption along the line of sight to
WD0455-282 with three velocity components. To our knowledge, this is the first
such detection of multi-component circumstellar absorption along the line of
sight to a white dwarf.Comment: 19 pages, 23 figures, 8 tables. Accepted for publication in the
Monthly Notices of the Royal Astronomical Societ
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