4,663 research outputs found
Modeling the Links between Biodiversity, Ecosystem Services and Human Wellbeing in the Context of Climate Change: Results from an Econometric Analysis on the European Forest Ecosystems
25 p.The paper conducts an empirical investigation on the complex relationship between biodiversity and the values of ecosystem goods and services that are supported by biodiversity and ecosystem functioning, aiming to produce an econometric quantification of the magnitudes involved. Furthermore, we operate this study at a in the context of global climate change, which is considered one of the major drivers today that alter the pattern of biodiversity distribution, affect the ecosystem functioning and change the flows of ecosystem goods and services to be provided by a healthy ecosystem. In the paper, we first built a composite biodiversity indicator on the concept of Natural Capital Index so as to integrate information regarding the quantitative and qualitative changes of ecosystems driven by warming climate conditions. Furthermore, the composite indicator is integrated into the econometric specification so as to capture the marginal impacts of changes in biodiversity on the value of ecosystem goods and services due to climate change. The econometric problem is solved in a structural simultaneous system using three-stage-least-squares (3SLS) to analyze climate change impacts on forest ecosystems and the respective ecosystem service values across 17 European countries
Mechanical detection of carbon nanotube resonator vibrations
Bending-mode vibrations of carbon nanotube resonator devices were
mechanically detected in air at atmospheric pressure by means of a novel
scanning force microscopy method. The fundamental and higher order bending
eigenmodes were imaged at up to 3.1GHz with sub-nanometer resolution in
vibration amplitude. The resonance frequency and the eigenmode shape of
multi-wall nanotubes are consistent with the elastic beam theory for a doubly
clamped beam. For single-wall nanotubes, however, resonance frequencies are
significantly shifted, which is attributed to fabrication generating, for
example, slack. The effect of slack is studied by pulling down the tube with
the tip, which drastically reduces the resonance frequency
Marine ecosystem services: Linking indicators to their classification
© 2014 Elsevier Ltd. All rights reserved. There is a multitude of ecosystem service classifications available within the literature, each with its own advantages and drawbacks. Elements of them have been used to tailor a generic ecosystem service classification for the marine environment and then for a case study site within the North Sea: the Dogger Bank. Indicators for each of the ecosystem services, deemed relevant to the case study site, were identified. Each indicator was then assessed against a set of agreed criteria to ensure its relevance and applicability to environmental management. This paper identifies the need to distinguish between indicators of ecosystem services that are entirely ecological in nature (and largely reveal the potential of an ecosystem to provide ecosystem services), indicators for the ecological processes contributing to the delivery of these services, and indicators of benefits that reveal the realized human use or enjoyment of an ecosystem service. It highlights some of the difficulties faced in selecting meaningful indicators, such as problems of specificity, spatial disconnect and the considerable uncertainty about marine species, habitats and the processes, functions and services they contribute to
Spatial and temporal variability of precipitation and drought in Portugal
The spatial variability of precipitation and drought are investigated for Portugal using monthly precipitation from 74 stations and minimum and maximum temperature from 27 stations, covering the common period of 1941–2006. Seasonal precipitation and the corresponding percentages in the year, as well as the precipitation concentration index (PCI), was computed for all 74 stations and then used as an input matrix for an R-mode principal component analysis to identify the precipitation patterns. The standardized precipitation index at 3 and 12 month time scales were computed for all stations, whereas the Palmer Drought Severity Index (PDSI) and the modified PDSI for Mediterranean conditions (MedPDSI) were computed for the stations with temperature data. The spatial patterns of drought over Portugal were identified by applying the S-mode principal component analysis coupled with varimax rotation to the drought indices matrices. The result revealed two distinct sub-regions in the country relative to both precipitation regimes and drought variability. The analysis of time variability of the PC scores of all drought indices allowed verifying that there is no linear trend indicating drought aggravation or decrease. In addition, the analysis shows that results for SPI-3, SPI-12, PDSI and MedPDSI are coherent among them
The Economic Impacts of Biodiversity Policy for Improving the Climate Regulating Services Provided by EU Natura 2000 Habitats
22 p.We adopted the state-of-the-art methodologies to quantify the total carbon stocked by Natura 2000 habitats as well as to project the future changes of carbon stocks influenced by alternative policy options for the management of Natura 2000 habitats by 2020. Our results show that the N2K network currently stores around 9.6 billion tonnes of Carbon, equivalent to 35 billion tonnes of CO2, which is estimated to be worth between €607 billion and €1,130 billion (stock value in 2010), depending on the price attached to a ton of carbon. Of the different ecosystems the forest habitats contain the highest carbon value in the network, ranging between €318 and €610 billion in 2010. Furthermore, our results also show that in the future these carbon values can be increased. A policy scenario (Policy ON), where full Protected Area coverage (terrestrial PAs + fuller MPAs) with a move to full favourable conservation status is estimated to generate a gain of at least a total of 1.71-2.86% by 2020 compared to a policy inaction scenario (Policy OFF), where no additional action is taken to conserve the current Natura 2000 sites over the next decade
Splash control of drop impacts with geometric targets
Drop impacts on solid and liquid surfaces exhibit complex dynamics due to the
competition of inertial, viscous, and capillary forces. After impact, a liquid
lamella develops and expands radially, and under certain conditions, the outer
rim breaks up into an irregular arrangement of filaments and secondary
droplets. We show experimentally that the lamella expansion and subsequent
break up of the outer rim can be controlled by length scales that are of
comparable dimension to the impacting drop diameter. Under identical impact
parameters, ie. fluid properties and impact velocity, we observe unique
splashing dynamics by varying the target cross-sectional geometry. These
behaviors include: (i) geometrically-shaped lamellae and (ii) a transition in
splashing stability, from regular to irregular splashing. We propose that
regular splashes are controlled by the azimuthal perturbations imposed by the
target cross-sectional geometry and that irregular splashes are governed by the
fastest-growing unstable Plateau-Rayleigh mode
Quantum corrections to gravity and their implications for cosmology and astrophysics
The quantum contributions to the gravitational action are relatively easy to
calculate in the higher derivative sector of the theory. However, the
applications to the post-inflationary cosmology and astrophysics require the
corrections to the Einstein-Hilbert action and to the cosmological constant,
and those we can not derive yet in a consistent and safe way. At the same time,
if we assume that these quantum terms are covariant and that they have relevant
magnitude, their functional form can be defined up to a single free parameter,
which can be defined on the phenomenological basis. It turns out that the
quantum correction may lead, in principle, to surprisingly strong and
interesting effects in astrophysics and cosmology.Comment: 15 pages, LaTeX, WS style, contribution to the Proceedings of the
QFEXT-2011 conference in the Centro de Ciencias de Benasque Pedro Pasqual,
Spai
Efficiency removal of copper from potable water using a pine bark porous media
All over the world the presence of heavy metals in water supply sources has been raising great concern in terms of public health since many epidemiologic studies confirm the potential carcinogenic effect of these pollutants at concentrations above acceptable standards. Because copper removal is the most frequent option to achieve a safe drinking water, the development of more efficient and sustainable water treatment
technologies is extremely relevant.
Reactive filtration using natural sorbent materials constitutes a promising and suitable process for drinking water treatment as a sustainable alternative to the conventional sand porous media, due to the their additional
sorptive. Additionally, the use of natural materials abundant in the region as a by-product from regional industrial activity enhances the sustainability of these emerging treatment solutions.
This work presents results and a few conclusions based on a laboratorial study performed to evaluate the efficiency of copper removal from potable water using a pine bark porous media under different experimental conditions for relevant hydraulic and physic-chemical parameters. Langmuir and linear isotherms were used to describe the sorption equilibrium data. The obtained lab-scale results allowed to establish sorption kinetics and showed removal efficiencies higher than 90%.Fundação para a Ciência e a Tecnologia (FCT
n-Dimensional FLRW Quantum Cosmology
We introduce the formalism of quantum cosmology in a
Friedmann-Lema\^itre-Robertson-Walker (FLRW) universe of arbitrary dimension
filled with a perfect fluid with equation of state. First we
show that the Schutz formalism, developed in four dimensions, can be extended
to a n-dimensional universe. We compute the quantum representant of the scale
factor , in the Many-Worlds, as well as, in the de Broglie-Bohm
interpretation of quantum mechanics. We show that the singularities, which are
still present in the n-dimensional generalization of FLRW universe, are
excluded with the introduction of quantum theory. We quantize, via the de
Broglie-Bohm interpretation of quantum mechanics, the components of the Riemann
curvature tensor in a tetrad basis in a n-dimensional FLRW universe filled with
radiation (). We show that the quantized version of the
Ricci scalar are perfectly regular for all time . We also study the behavior
of the energy density and pressure and show that the ratio
tends to the classical value only for , showing that is
somewhat privileged among the other dimensions. Besides that, as ,
.Comment: 12 pages, revtex, minor modification
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