Kinetic Monte Carlo simulations of the growth of polymer crystals

Based upon kinetic Monte Carlo simulations of crystallization in a simple polymer model we present a new picture of the mechanism by which the thickness of lamellar polymer crystals is constrained to a value close to the minimum thermodynamically stable thickness, l_{min}. The free energetic costs of the polymer extending beyond the edges of the previous crystalline layer and of a stem being shorter than l_{min} provide upper and lower constraints on the length of stems in a new layer. Their combined effect is to cause the crystal thickness to converge dynamically to a value close to l_{min} where growth with constant thickness then occurs. This description contrasts with those given by the two dominant theoretical approaches. However, at small supercoolings the rounding of the crystal profile does inhibit growth as suggested in Sadler and Gilmer's entropic barrier model.Comment: 12 pages, 13 figures, revte

The physical determinants of the thickness of lamellar polymer crystals

Based upon kinetic Monte Carlo simulations of crystallization in a simple polymer model we present a new picture of the mechanism by which the thickness of lamellar polymer crystals is constrained to a value close to the minimum thermodynamically stable thickness. This description contrasts with those given by the two dominant theoretical approaches.Comment: 4 pages, 4 figures, revte

Resort Based Management Web GIS Towards Cyber Conservation in Indonesia

Biodiversity loss is a global issue and is especially of pressing concern in mega diverse countries, such as Indonesia. To prevent any further catastrophe, the Ministry of Forestry and Environment of Republic of Indonesia has been promoting the resort based management to be implemented in Indonesia to maximize the performance of conservation activity. The lack of data standardization made it hard to organize and manage archipelagic country that consist 17,504 islands with no technology provision in most of them. In this paper we develop a framework of integration mobile-web technology for biodiversity and conservation in Indonesia. We introduced a new framework to maintain the biodiversity and conservation data in Indonesia

Climate-induced changes in river flow regimes will alter future bird distributions

Anthropogenic forcing of the climate is causing an intensification of the global water cycle, leading to an increase in the frequency and magnitude of floods and droughts. River flow shapes the ecology of riverine ecosystems and climate-driven changes in river flows are predicted to have severe consequences for riverine species, across all levels of trophic organization. However, understanding species' responses to variation in flow is limited through a lack of quantitative modelling of hydroecological interactions. Here, we construct a Bioclimatic Envelope Model (BEM) ensemble based on a suite of plausible future flow scenarios to show how predicted alterations in flow regimes may alter the distribution of a predatory riverine species, the White-throated Dipper (Cinclus cinclus). Models predicted a gradual diminution of dipper probability of occurrence between present day and 2098. This decline was most rapid in western areas of Great Britain and was principally driven by a projected decrease in flow magnitude and variability around low flows. Climate-induced changes in river flow may, therefore, represent a previously unidentified mechanism by which climate change may mediate range shifts in birds and other riverine biota

Ecospace:a unified framework for understanding variation in terrestrial biodiversity

AbstractUnderstanding patterns in biodiversity is a core ambition in ecological research. Existing ecological theories focusing on individual species, populations, communities, or niches aid in understanding the determinants of biodiversity patterns, yet very few general models for biodiversity have emerged from simplistic approaches. We propose that a systematic, low-dimensional representation of environmental space with building blocks adopted from gradient, niche, metapopulation and assembly theory may unite old and new aspects of biodiversity theory and improve our understanding of variation in terrestrial biodiversity.We propose the term ecospace to cover the local conditions and resources underlying diversity. Our definition of ecospace encompasses abiotic position, biotic expansion and spatiotemporal continuity, which all affect the biodiversity of a biotope (α-diversity). Position refers to placement along abiotic gradients such as temperature, soil pH and fertility, leading to environmental filtering known from classical community theory. Expansion represents the build-up and diversification of organic matter that are not strictly given by position. Continuity refers to the spatiotemporal extension of position and expansion.Biodiversity is scale dependent. The contribution of one biotope to large scale diversity must be estimated by considering its unique contribution to the species richness of the surrounding landscape or region or to the biodiversity of the entire planet. In addition to the relationship between ecospace and biotope richness (α-diversity), we also propose a relation between the uniqueness of the biotope ecospace and the unique contribution of species to the surrounding larger-scale richness.Whereas the impacts of ecospace position and continuity on biodiversity have been studied in isolation, studies comparing or combining them are rare. Furthermore, biotic expansion has never been fully developed as a determinant of biodiversity, ignoring the megadiverse carbon-depending groups of insects and fungi. Precursors of the ecospace concept have been presented over the last 70 years, but they were never fully developed conceptually for terrestrial biodiversity or applied to prediction of biodiversity.Ecospace unites classical and – at times – contradicting theories such as niche theory, island biogeography theory and a suite of community assembly theories into one framework for further development of a general theory of terrestrial biodiversity

Unravelling the complexities of biotic homogenization and heterogenization in the British avifauna

Abstract Biotic homogenization is a process whereby species assemblages become more similar through time. The standard way of identifying the process of biotic homogenization is to look for decreases in spatial beta?diversity. However, using a single assemblage-level metric to assess homogenization can mask important changes in the occupancy patterns of individual species. Here, we analysed changes in the spatial beta?diversity patterns (i.e. biotic heterogenization or homogenization) of British bird assemblages within 30?km???30?km regions between two periods (1988?1991 and 2008?2011). We partitioned the change in spatial beta?diversity into extirpation and colonization-resultant change (i.e. change in spatial beta?diversity within each region resulting from both extirpation and colonization). We used measures of abiotic change in combination with Bayesian modelling to disentangle the drivers of biotic heterogenization and homogenization. We detected both heterogenization and homogenization across the two time periods and three measures of diversity (taxonomic, phylogenetic, and functional). In addition, both extirpation and colonization contributed to the observed changes, with heterogenization mainly driven by extirpation and homogenization by colonization. These assemblage-level changes were primarily due to shifting occupancy patterns of generalist species. Compared to habitat generalists, habitat specialists had significantly (i) higher average contributions to colonization-resultant change (indicating heterogenization within a region due to colonization) and (ii) lower average contributions to extirpation-resultant change (indicating homogenization from extirpation). Generalists showed the opposite pattern. Increased extirpation-resultant homogenization within regions was associated with increased urban land cover and decreased habitat diversity, precipitation, and temperature. Changes in extirpation-resultant heterogenization and colonization-resultant heterogenization were associated with differences in elevation between regions and changes in temperature and land cover. Many of the ?winners? (i.e. species that increased in occupancy) were species that had benefitted from conservation action (e.g. buzzard (Buteo buteo)). The ?losers? (i.e. those that decreased in occupancy) consisted primarily of previously common species, such as cuckoo (Cuculus canorus). Our results show that focusing purely on changes in spatial beta?diversity over time may obscure important information about how changes in the occupancy patterns of individual species contribute to homogenization and heterogenization

Delivering sustainable, resilient and liveable cities via transformed governance

In the context of steadily declining Natural Capital and universal recognition of the imperative to reverse this trend before we get to the point that nature is not able to restore itself, cities have a crucial role to play. The UK Government commissioned a comprehensive study into the value of biodiversity, and by extension nature, reinforcing “why we should change our ways”—yet what is missing is the “how?”. This paper uniquely describes both the “how?” and a conclusive demonstration of the remarkable benefits of implementing it in a city. Critical to this process, it took a UK Parliamentary Inquiry to reveal that nature has become invisible within the economy, yet the ecological ecosystem services nature provides have enormous benefits to both people and the economy. Therefore integration—or seamless weaving—of urban greenspace and nature into people's lives and the places where they live, work, and spend their leisure time is vital. Moreover, what nature does not provide must be provided by engineered systems, and these have an economic cost; put another way, there are enormous cost savings to be made by taking advantage of what nature provides. In addressing these issues, this paper is the definitive paper from a 20-year portfolio of research on how to bring about transformative change in the complex system-of-systems that make up our cities, providing as it does the crucial in-depth research into the many diverse strands of governance—the last link in a chain of the creation, testing and proof of efficacy of methodologies underpinning a theory and practice of change for infrastructure and cities. The impact of this portfolio of research on Birmingham is two-fold: the Star Framework that placed natural environment considerations at the heart of all decision-making in the city, and the successful bid for the largest of the UK Future Parks Accelerator awards. While both are transformative in their different ways, yet mutually supportive, the latter enabled the design of a suite of system interventions from which the value of Birmingham's greenspaces is estimated to rise from £11.0 billion to £14.4 billion—a remarkable return on investment from the research's conceptualization of Birmingham's urban greenspace as a “business” (with its associated business models). In achieving this, the necessary enablers of thinking and practicing systemically, seamlessly working across disciplinary boundaries, an unusually strong focus on both the aspirations of all stakeholders and the context in question to define “the problem,” and the testing of proposed system intervention(s) both now and in the future have been iteratively combined. However, it is the critical enabling steps of identifying the complete range of value-generating opportunities that the interventions offer, formulating them into alternative business models to underpin the case for change and ensuring that they are synergistic with all the dimensions of governance that yielded the profound outcomes sought

Impact of human foraging on tree diversity, composition, and abundance in a tropical rainforest

Tropical forest tree communities are structured by a range of large-scale drivers including elevation, certain high-impact anthropogenic activities (e.g., deforestation), and fires. However, low-impact human activities such as foraging may also be subtly but notably altering the composition of tropical forest tree communities. The study assessed the (i) differences in species diversity, patterns of relative abundance, and pairwise beta diversity between trees with edible and inedible fruits and seeds along an elevation gradient, and (ii) impact of human foraging on the forest tree communities in Oban Division of Cross River National Park, Nigeria. Fifteen permanent 40 by 40 m plots were established along an elevational gradient (120–460 m above mean sea level). All trees of 0.1 m diameter at breast height (dbh) and above were measured, identified, and, with the aid of structured questionnaires, classified into those with edible and inedible fruits/seeds. A total of 35 edible species with density of 128 stems/hectare and basal area of 11.99 m2/hectare, and 109 inedible species with density of 364 stems/hectare and basal area of 22.42 m2/hectare were sampled. However, the evenness of edible and inedible species was similar at pooled and plot levels. For inedible species, there was a positive relationship between pairwise beta diversity and elevation, and this was driven mainly by turnover. In contrast, edible species exhibited a non-significant trend between elevation and beta diversity. Thus, the study showed that human foraging of edible fruits may have subtly influenced patterns of species diversity and community structure in this tropical forest.FUNDING: Petroleum Technology Development Fund (PTDF), Nigeria, Grant/Award Number: PTDF/ED/PHD/ASA/1342/18.info:eu-repo/semantics/publishedVersio