Network 'small-world-ness': a quantitative method for determining canonical network equivalence

Background: Many technological, biological, social, and information networks fall into the broad class of 'small-world' networks: they have tightly interconnected clusters of nodes, and a shortest mean path length that is similar to a matched random graph (same number of nodes and edges). This semi-quantitative definition leads to a categorical distinction ('small/not-small') rather than a quantitative, continuous grading of networks, and can lead to uncertainty about a network's small-world status. Moreover, systems described by small-world networks are often studied using an equivalent canonical network model-the Watts-Strogatz (WS) model. However, the process of establishing an equivalent WS model is imprecise and there is a pressing need to discover ways in which this equivalence may be quantified. Methodology/Principal Findings: We defined a precise measure of 'small-world-ness' S based on the trade off between high local clustering and short path length. A network is now deemed a 'small-world' if S. 1-an assertion which may be tested statistically. We then examined the behavior of S on a large data-set of real-world systems. We found that all these systems were linked by a linear relationship between their S values and the network size n. Moreover, we show a method for assigning a unique Watts-Strogatz (WS) model to any real-world network, and show analytically that the WS models associated with our sample of networks also show linearity between S and n. Linearity between S and n is not, however, inevitable, and neither is S maximal for an arbitrary network of given size. Linearity may, however, be explained by a common limiting growth process. Conclusions/Significance: We have shown how the notion of a small-world network may be quantified. Several key properties of the metric are described and the use of WS canonical models is placed on a more secure footing

Experiences of assessment in data and security courses using personal response systems

This paper details an experience report of two interventions which explored the use of a audience response system in summative assessment in two different ways within a conversion Masters degree programme. One course explored students understanding of topics and self-assessment of ability through small multiple-choice quizzes. The other course was based around cyber security and used the audience response system to ensure engagement with the pre-class reading material. Both interventions were designed in an attempt to encourage students to engage more effectively with the material. This paper aims to identify and contrast the ways in which the audience response system was used in assessment in higher education computing science with a view to suggesting key considerations for implementing such an intervention

Public perceptions of mangrove forests matter for their conservation

Abstract not available

The effect of salinity on growth and weight loss of juvenile plaice (Pleuronectes platessa, L): An experimental test

Previous population estimates of the 0+ plaice (Pleuronectes platessa L.) in the Firth of Forth, east central Scotland, did not take account of the Forth estuary west of the Forth bridges. Previous work found plaice in the estuary grew as fast as, or faster than, the outer firth plaice. It was hypothesised that salinity may affect growth rates of early 0+ plaice. This hypothesis was tested in a laboratory experiment, by exposing juvenile plaice to three different, but naturally — experienced by the juveniles, salinities; 25, 30 and 35. Plaice fed a minimum ration did not grow in length. Mean weight decreased at all three salinities, however, the lowest weight loss was found at the lowest salinity (25) and the highest weight loss was found at the highest salinity (35). The minimum feeding ration was halted and plaice were then fed ad libitum. Consumption rates were not significantly different during the ad libitum feeding, while significant differences in mean weight change were found between the highest and lowest salinities

Harnessing the climate mitigation, conservation and poverty alleviation potential of seagrasses: prospects for developing blue carbon initiatives and payment for ecosystem service programmes

Seagrass ecosystems provide numerous ecosystem services that support coastal communities around the world. They sustain abundant marine life as well as commercial and artisanal fisheries, and help protect shorelines from coastal erosion. Additionally, seagrass meadows are a globally significant sink for carbon and represent a key ecosystem for combating climate change. However, seagrass habitats are suffering rapid global decline. Despite recognition of the importance of “Blue Carbon,” no functioning seagrass restoration or conservation projects supported by carbon finance currently operate, and the policies and frameworks to achieve this have not been developed. Yet, seagrass ecosystems could play a central role in addressing important international research questions regarding the natural mechanisms through which the ocean and the seabed can mitigate climate change, and how ecosystem structure links to service provision. The relative inattention that seagrass ecosystems have received represents both a serious oversight and a major missed opportunity. In this paper we review the prospects of further inclusion of seagrass ecosystems in climate policy frameworks, with a particular focus on carbon storage and sequestration, as well as the potential for developing payment for ecosystem service (PES) schemes that are complementary to carbon management. Prospects for the inclusion of seagrass Blue Carbon in regulatory compliance markets are currently limited; yet despite the risks the voluntary carbon sector offers the most immediately attractive avenue for the development of carbon credits. Given the array of ecosystem services seagrass ecosystems provide the most viable route to combat climate change, ensure seagrass conservation and improve livelihoods may be to complement any carbon payments with seagrass PES schemes based on the provision of additional ecosystem services

Carbon stable isotopes in estuarine sediments and their utility as migration markers for nursery studies in the Firth of Forth and Forth Estuary, Scotland

The stable carbon isotope ratios (?13C) of the organic fraction of intertidal sediments in the Forth Estuary and the Firth of Forth, Scotland, were measured to determine if terrestrially derived carbon was present in the estuarine sediments. It was hypothesised that differences in the inputs from marine vs. terrestrial sources to the organic carbon of estuarine and marine sediments, as well as differences in ambient seawater stable oxygen isotope (?18O) ratios between the estuary and the Outer Firth, would allow the use of these two stable isotopes as habitat markers for juvenile plaice (Pleuronectes platessa), to allow determination of nursery habitats. Muddy and sandy sediments from the estuary and sandy sediments from the Outer Firth were sampled and ?13C measured. Juvenile plaice were caught at two estuarine sites and at two Outer Firth sites and otoliths were removed for ?13C and ?18O analysis. The sandy sediments in the estuary showed a strong gradient of ?13C enrichment with distance down the estuary, while the muddy sediments showed a much shallower gradient. ?13C and ?18O measured in the carbonate of juvenile plaice otoliths showed no clear difference between otoliths of fish caught at one of the estuarine sites and at the two Outer Firth sites. However, the isotope ratios of both carbon and oxygen in plaice otoliths from the other estuarine site showed the expected trend of depletion in the heavier isotopes. While the measurements recorded here did not conclusively distinguish between otoliths from juveniles caught in the estuarine site and those caught in the other three sites, they show that stable isotopes have potential to distinguish between estuarine habitats with terrestrial carbon inputs, and coastal marine habitats with predominantly marine carbon inputs

Speed of exploration and risk-taking behavior are linked to corticosterone titres in zebra finches

The existence of consistent individual differences in behavioral strategies ("personalities" or coping styles) has been reported in several animal species. Recent work in great tits has shown that such traits are heritable and exhibit significant genetic variation. Free-living birds respond to environmental stresses by up-regulating corticosterone production. Behavior during mild stress can occur in accordance to two types of coping styles, i.e. active and passive. Using artificially selected lines of zebra finches that vary in the amount of corticosterone produced in response to a manual restraint stressor we ran three "personality" experiments. We show that birds in the different corticosterone lines differ in their exploratory and risk-taking behaviors. There was an increase in exploratory behavior as corticosterone titre increased but only in the low corticosterone line. Birds in high corticosterone line showed greater risk-taking behavior than birds in the other lines. Thus, in general, higher levels of circulating corticosterone following a mild stress result in greater exploratory behavior and greater risk taking. This study shows that lines of animals selected for endocrine hormonal responses differ in their "coping" styles or "personalities". © 2007 Elsevier Inc. All rights reserved.Link_to_subscribed_fulltex

Postural control in Parkinson patients: a proprioceptive problem?

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