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Search Results: 1 - 10 of 5144 matches for " Nicholas Polunin "
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Ecological States and the Resilience of Coral Reefs
Tim McClanahan,Nicholas Polunin,Terry Done
Ecology and Society , 2002,
Abstract: We review the evidence for multiple ecological states and the factors that create ecological resilience in coral reef ecosystems. There are natural differences among benthic communities along gradients of water temperature, light, nutrients, and organic matter associated with upwelling-downwelling and onshore-offshore systems. Along gradients from oligotrophy to eutrophy, plant-animal symbioses tend to decrease, and the abundance of algae and heterotrophic suspension feeders and the ratio of organic to inorganic carbon production tend to increase. Human influences such as fishing, increased organic matter and nutrients, sediments, warm water, and transportation of xenobiotics and diseases are common causes of a large number of recently reported ecological shifts. It is often the interaction of persistent and multiple synergistic disturbances that causes permanent ecological transitions, rather than the succession of individual short-term disturbances. For example, fishing can remove top-level predators, resulting in the ecological release of prey such as sea urchins and coral-eating invertebrates. When sea urchins are not common because of unsuitable habitat, recruitment limitations, and diseases, and when overfishing removes herbivorous fish, frondose brown algae can dominate. Terrigenous sediments carried onto reefs as a result of increased soil erosion largely promote the dominance of turf or articulated green algae. Elevated nutrients and organic matter can increase internal eroders of reef substratum and a mixture of filamentous algae. Local conservation actions that attempt to reduce fishing and terrestrial influences promote the high production of inorganic carbon that is necessary for reef growth. However, global climate change threatens to undermine such actions because of increased bleaching and mortality caused by warm-water anomalies, weakened coral skeletons caused by reduced aragonite availability in reef waters, and increased incidence of diseases in coral reef species. Consequently, many coral reefs, including those that are heavily managed, have experienced net losses in accumulated inorganic carbon in recent decades and appear likely to continue this trend in coming decades. Reefs urgently need to be managed with a view to strengthening their resilience to the increased frequency and intensity of these pressures. Ecological targets must include the restoration or maintenance of species diversity, keystone species, spatial heterogeneity, refugia, and connectivity. Achieving these goals will require unprecedented cooperative synergy betw
Effects of Seismic Exploration on Mangrove Habitat in Tanzania
I Pring, NVC Polunin
Western Indian Ocean Journal of Marine Science , 2010,
Abstract: Abstract—Global demand for oil and gas has resulted in increased seismic exploration for new resources in environmentally sensitive areas. Reports of damage to ecosystem function have been reported, but the environmental effects of seismic exploration are largely undocumented. Key impacts in mangroves include tree removal and trampling. This paper reports on their effects in southeast Tanzania, through assessments of tree density and species distribution, incidence of local harvesting and changes in environmental conditions that might influence the biota. Seismic survey-related gaps in the canopy have not resulted in increases in mangrove recruitment, or affected microhabitat temperatures or salinity. However, seismic lines may have become access routes, leading to increased mangrove harvesting. There were few signs of recovery in the immediate vicinity of seismic lines, which appeared to be related to trampling effects on soil stability and changes in hydrology attributable to the loss of trees. Future research should target seedling and sapling abundance and growth rates, and soil structure, composition and nutrient levels. Recommended mitigation measures would involve the promotion of mangrove regeneration and the prevention of secondary impacts such as the use of lines as access routes, with monitoring of forest recovery.
Climate Warming, Marine Protected Areas and the Ocean-Scale Integrity of Coral Reef Ecosystems
Nicholas A. J. Graham, Tim R. McClanahan, M. Aaron MacNeil, Shaun K. Wilson, Nicholas V. C. Polunin, Simon Jennings, Pascale Chabanet, Susan Clark, Mark D. Spalding, Yves Letourneur, Lionel Bigot, René Galzin, Marcus C. ?hman, Kajsa C. Garpe, Alasdair J. Edwards, Charles R. C. Sheppard
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003039
Abstract: Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the 1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure, diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales, with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance. This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should be integrated into existing management frameworks and combined with policies to improve system-wide resilience to climate variation and change.
Three Philosophical Problems about Consciousness and their Possible Resolution  [PDF]
Nicholas Maxwell
Open Journal of Philosophy (OJPP) , 2011, DOI: 10.4236/ojpp.2011.11001
Abstract: Three big philosophical problems about consciousness are: Why does it exist? How do we explain and understand it? How can we explain brain-consciousness correlations? If functionalism were true, all three problems would be solved. But it is false, and that means all three problems remain unsolved (in that there is no other obvious candidate for a solution). Here, it is argued that the first problem cannot have a solution; this is inherent in the nature of explanation. The second problem is solved by recognizing that (a) there is an explanation as to why science cannot explain consciousness, and (b) consciousness can be explained by a different kind of explanation, empathic or “personalistic” explanation, compatible with, but not reducible to, scientific explanation. The third problem is solved by exploiting David Chalmers“principle of structural coherence”, and involves postulating that sensations experienced by us–visual, auditory, tactile, and so on–amount to minute scattered regions in a vast, multi dimensional “space” of all possible sensations, which vary smoothly, and in a linear way, throughout the space. There is also the space of all possible sentient brain processes. There is just one, unique one-one mapping between these two spaces that preserves continuity and linearity. It is this which provides the explanation as to why brain processes and sensations are correlated as they are. I consider objections to this unique-matching theory, and consider how the theory might be empirically confirmed.
Origins and Mechanisms in the Development of Major Mental Disorders: A Clinical Approach  [PDF]
Nicholas Pediaditakis
Journal of Behavioral and Brain Science (JBBS) , 2012, DOI: 10.4236/jbbs.2012.22030
Abstract: This paper considers the following collective significance of the shared, clinical characteristics of the major mental disorders (MMDs), their co-morbidities, overlaps and pharmacological responses with the following conclusions: 1) These disorders have a common, initial, neurodevelopmental origin. 2) They can occur probabilistically on susceptible individuals, on account of pre-existing, extreme, temperamental variances-signifying underlying structural variance. 3) Each of these syndromes can be considered the expression of disturbances in the overall, common, operating mode of brain function which normally ensures the synchrony, coordination, elegance and subtlety in the expression of all the brain’s higher faculties. 4) Lastly, this function is a complex, emergent phenomenon based on the individual’s temperamental/structural underlying makeup, switching intermittently from a normal phase to a pathologically, ordered one-the latter phase expressing itself with symptoms made up of expressing either/or, antithetical substitutes for each of the MMDs-similar to the fluctuations found in patient’s with Parkinson’s disease.
Origins and Mechanisms in the Development of Major Mental Disorders: A Clinical Approach  [PDF]
Nicholas Pediaditakis
Journal of Behavioral and Brain Science (JBBS) , 2012, DOI: 10.4236/jbbs.2012.22030
Abstract: This paper considers the following collective significance of the shared, clinical characteristics of the major mental disorders (MMDs), their co-morbidities, overlaps and pharmacological responses with the following conclusions: 1) These disorders have a common, initial, neurodevelopmental origin. 2) They can occur probabilistically on susceptible individuals, on account of pre-existing, extreme, temperamental variances-signifying underlying structural variance. 3) Each of these syndromes can be considered the expression of disturbances in the overall, common, operating mode of brain function which normally ensures the synchrony, coordination, elegance and subtlety in the expression of all the brain’s higher faculties. 4) Lastly, this function is a complex, emergent phenomenon based on the individual’s temperamental/structural underlying makeup, switching intermittently from a normal phase to a pathologically, ordered one-the latter phase expressing itself with symptoms made up of expressing either/or, antithetical substitutes for each of the MMDs-similar to the fluctuations found in patient’s with Parkinson’s disease.
Three Criticisms of Newton’s Inductive Argument in the Principia  [PDF]
Nicholas Maxwell
Advances in Historical Studies (AHS) , 2014, DOI: 10.4236/ahs.2014.31002
Abstract: In this paper, I discuss how Newton’s inductive argument of the Principia can be defended against criticisms leveled against it by Duhem, Popper and myself. I argue that Duhem’s and Popper’s criticisms can be countered, but mine cannot. It requires that we reconsider, not just Newton’s inductive argument in the Principia, but also the nature of science more generally. The methods of science, whether conceived along inductivist or hypothetico-deductivist lines, make implicit metaphysical presuppositions which rigorously require us to make them explicit within science so that they can be critically assessed, alternatives being developed and assessed, in the hope that they can be improved. Despite claiming to derive his law of gravitation by induction from phenomena without resource to hypotheses, Newton does nevertheless acknowledge in the Principia that his rules of reasoning make metaphysical presuppositions. To this extent, Newton has a more enlightened view of scientific method than most 20th and 21st century scientists and historians and philosophers of science.
Modelling Impacts of Socio-Economic Factors on Temporal Diffusion of PV-Based Communal Grids  [PDF]
Nicholas Opiyo
Smart Grid and Renewable Energy (SGRE) , 2015, DOI: 10.4236/sgre.2015.612026
Abstract: Impacts of socio-economic factors on temporal diffusions of solar electricity microgeneration systems in a rural developing community are modelled and simulated using an agent-based model (ABM). ABMs seek to capture the overall macro-effects of different micro-decisions in a virtual world; they model individual entities within a complex system and the rules that govern them to capture the overall effects of their interactions. Results showed that falling PV costs coupled with generally increasing grid electricity costs would lead to increased uptake of PV systems in such communities. On the other hand, high lending rates in most developing nations would stifle use of credit facilities in purchases of PV systems and thus diminishing their uptakes. Results also showed that introduction of favourable government policies in forms of subsidies would strongly stimulate PV installations in such communities. Social acceptance is important for diffusion of any new technology into a given market and more so with solar systems; results show that neighbourhood influence plays major roles in PV diffusions with many households installing PV systems if their neighbours within a given sensing radius do the same. Results also showed that requiring a certain percentage of neighbours to have installed PV before a household considered doing the same could have negative effects on PV installations as decisions to install PV are influenced by many independent and dependent factors and not by neighbourhood threshold alone.
Environmental Standards and Trade Volume  [PDF]
Nicholas Mangee, Bruce Elmslie
Modern Economy (ME) , 2010, DOI: 10.4236/me.2010.12010
Abstract: This paper presents a theoretical and empirical analysis of the effects of environmental regulation on bilateral trade volume. We use a gravity model of trade flows and find weak evidence that differences in regulation are a source of comparative advantage. We also find evidence against the racetothebottom hypothesis in that increases in standards in both high and low standard countries increase bilateral trade volume. We use 1999 data on GDP, population, and environmental stringency for 39 countries.
Recommending Who to Follow on Twitter Based on Tweet Contents and Social Connections  [PDF]
Evgenia Tsourougianni, Nicholas Ampazis
Social Networking (SN) , 2013, DOI: 10.4236/sn.2013.24016
Abstract:

In this paper, we examine methods that can provide accurate results in a form of a recommender system within a social networking framework. The social networking site of choice is Twitter, due to its interesting social graph connections and content characteristics. We built a recommender system which recommends potential users to follow by analyzing their tweets using the CRM114 regex engine as a basis for content classification. The evaluation of the recommender system was based on a dataset generated from real Twitter users created in late 2009.

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