1,608 research outputs found
Strong seasonal differences of bacterial polysaccharide utilization in the North Sea over an annual cycle
Marine heterotrophic bacteria contribute considerably to global carbon cycling, in part by utilizing phytoplankton-derived polysaccharides. The patterns and rates of two different polysaccharide utilization modes - extracellular hydrolysis and selfish uptake - have previously been found to change during spring phytoplankton bloom events. Here we investigated seasonal changes in bacterial utilization of three polysaccharides, laminarin, xylan and chondroitin sulfate. Strong seasonal differences were apparent in mode and speed of polysaccharide utilization, as well as in bacterial community compositions. Compared to the winter month of February, during the spring bloom in May, polysaccharide utilization was detected earlier in the incubations and a higher portion of all bacteria took up laminarin selfishly. Highest polysaccharide utilization was measured in June and September, mediated by bacterial communities that were significantly different from spring assemblages. Extensive selfish laminarin uptake, for example, was detectible within a few hours in June, while extracellular hydrolysis of chondroitin was dominant in September. In addition to the well-known Bacteroidota and Gammaproteobacteria clades, the numerically minor verrucomicrobial clade Pedosphaeraceae could be identified as a rapid laminarin utilizer. In summary, polysaccharide utilization proved highly variable over the seasons, both in mode and speed, and also by the bacterial clades involved
Emissions of air pollutants for the World Energy Outlook 2012 energy scenarios
This report examines global emissions of major air pollutants (SO2, NOx, PM2.5) resulting from energy scenarios developed for the World Energy Outlook 2012 (OECD/IEA, 2012). Estimates include emissions for 25 regions according to the aggregation used in the IEA World Energy Model (WEM). Emissions have been estimated using the IIASA GAINS model.
The 2012 Outlook discusses four energy pathways for the next 25 years. The central scenario, the New Policies (NP) scenario, takes into account recently announced policy commitments and assumes that they are implemented in a cautious manner. The Current Policies (CP) scenario assumes no new policies beyond those adopted by mid-2012. The High Energy Efficiency (HE) scenario simulates the effects of policies aimed at promoting energy efficiency in all countries in the world. The 450 scenario assumes radical policy action consistent with limiting the global temperature increase to two degrees Celsius (2 oC).
All the four pathways were implemented into the GAINS model. Next, emissions of air pollutants were calculated. Calculations take into account the current air pollution control legislation and policies in each country or region as adopted or in the pipeline by mid-2012. Presented in this report estimates do not include emissions from international shipping as well as cruising emissions from aviation. They also do not include emissions from biomass burning (deforestation, savannah burning, and vegetation fires).
In 2010, world emissions of SO2 from sources covered in this report were about 86 million tons. OECD countries contributed 21 percent of this total. Implementation of pollution controls for the Current Policies Scenario causes an eight percent decrease in world emissions of SO2 in 2020 compared with 2010. This is a combined result of reducing emissions from OECD countries (by about 24 percent), increase in India, and a decrease in China, Russia, South Africa, and Middle East. After 2020, emissions from many non-OECD countries continue rising, which causes an increase of world emissions by about five million tons until 2035. Particularly remarkable is the increase in SO2 emissions in India. The corresponding numbers for NOx are: 85 million tons in 2010 (of which 35 percent originated from the OECD countries), five percent decrease until 2020 and next increase until 2035 by 12 million tons. Emissions of PM2.5 (43 million tons in 2010) are dominated by sources from non-OECD countries -- 90 percent of total. Changes in the emissions until 2035 are rather small, with a seven percent decrease in the OECD countries and a stabilization in the developing world.
The 450 Scenario causes an important reduction in emissions of air pollutants. In 2035, the emissions of SO2 are 36 percent lower than in the Current Policies case. Emissions of NOx decrease by 32 percent and those of PM2.5 by 11 percent. Emissions for the New Policies and the High Energy Efficiency scenarios lie between those for the Current Policies and the 450 scenarios.
Costs of controlling emissions of sulphur and nitrogen oxides and PM (dust) in 2010 are estimated at about 217 billion Euros/a. Until 2035, these costs increase in the Current Policies Scenario by more than a factor of two, which is due to higher activity levels and increasing stringency of controls. In 2035, 61 percent of the total costs are the expenditures on reducing emissions from road transport. The 450 Scenario brings 32 percent cost savings in 2035 compared to the Current Policies case.
This study also estimates health impacts of air pollution in Europe, China and India in terms of life years lost (YOLL) attributable to the exposure from anthropogenic emissions of PM2.5. PM concentrations as in 2010 cause a loss of about 2.2 billion life-years. This estimate is dominated by impacts in China and India. The Current Policies Scenario implies an increase of the YOLL indicator in 2035 by 46 percent to 3.3 billion. Decrease of PM2.5 concentrations as in the 450 Scenario in 2035 saves about 870 million life-years.
Lower impact indicators and lower control costs in the scenarios that simulate effects of policies towards reducing energy demand and the use of fossil fuels clearly demonstrate important co-benefits of such policies for air pollution
Emissions of air pollutants for the World Energy Outlook 2011 Energy Scenarios
This report examines global emissions of major air pollutants (SO2, NOx, PM2.5) resulting from energy scenarios developed for the World Energy Outlook 2012 (OECD/IEA, 2012). Estimates include emissions for 25 regions according to the aggregation used in the IEA World Energy Model (WEM). Emissions have been estimated using the IIASA GAINS model.
The 2012 Outlook discusses four energy pathways for the next 25 years. The central scenario, the New Policies (NP) scenario, takes into account recently announced policy commitments and assumes that they are implemented in a cautious manner. The Current Policies (CP) scenario assumes no new policies beyond those adopted by mid-2012. The High Energy Efficiency (HE) scenario simulates the effects of policies aimed at promoting energy efficiency in all countries in the world. The 450 scenario assumes radical policy action consistent with limiting the global temperature increase to two degrees Celsius.
All four pathways were implemented into the GAINS model. Next, emissions of air pollutants were calculated. Calculations take into account the current air pollution control legislation and policies in each country or region as adopted or in the pipeline by mid-2012. Presented in this report estimates do not include emissions from international shipping as well as cruising emissions from aviation. They also do not include emissions from biomass burning (deforestation, savannah burning, and vegetation fires).
In 2010, world emissions of SO2 from sources covered in this report were about 86 million tons. OECD countries contributed 21 percent of this total. Implementation of pollution controls for the Current Policies Scenario causes an eight percent decrease in world emissions of SO2 in 2020 compared with 2010. This is a combined result of reducing emissions from OECD countries (by about 24 percent), increase in India, and a decrease in China, Russia, South Africa, and Middle East. After 2020, emissions from many non-OECD countries continue rising, which causes an increase of world emissions by about five million tons until 2035. Particularly remarkable is the increase in SO2 emissions in India. The corresponding numbers for NOx are: 85 million tons in 2010 (of which 35 percent originated from the OECD countries), five percent decrease until 2020 and next increase until 2035 by 12 million tons. Emissions of PM2.5 (43 million tons in 2010) are dominated by sources from non-OECD countries - 90 percent of total. Changes in the emissions until 2035 are rather small, with a seven percent decrease in the OECD countries and a stabilization in the developing world.
The 450 Scenario causes an important reduction in emissions of air pollutants. In 2035, the emissions of SO2 are 36 percent lower than in the Current Policies case. Emissions of NOx decrease by 32 percent and those of PM2.5 by 11 percent. Emissions for the New Policies and the High Energy Efficiency scenarios lie between those for the Current Policies and the 450 scenarios.
Costs of controlling emissions of sulphur and nitrogen oxides and PM (dust) in 2010 are estimated at about 217 billion Euros/a. Until 2035, these costs increase in the Current Policies Scenario by more than a factor of two, which is due to higher activity levels and increasing stringency of controls. In 2035, 61 percent of the total costs are the expenditures on reducing emissions from road transport. The 450 Scenario brings 32 percent cost savings in 2035 compared to the Current Policies case.
This study also estimates health impacts of air pollution in Europe, China and India in terms of life years lost (YOLL) attributable to the exposure from anthropogenic emissions of PM2.5. PM concentrations as in 2010 cause a loss of about 2.2 billion life-years. This estimate is dominated by impacts in China and India. The Current Policies Scenario implies an increase of the YOLL indicator in 2035 by 46 percent to 3.3 billion. Decrease of PM2.5 concentrations as in the 450 Scenario in 2035 saves about 870 million life-years.
Lower impact indicators and lower control costs in the scenarios that simulate effects of policies towards reducing energy demand and the use of fossil fuels clearly demonstrate important co-benefits of such policies for air pollution
Magnetic skyrmion lattices in heavy fermion superconductor UPt3
Topological analysis of nearly SO(3)_{spin} symmetric Ginzburg--Landau
theory, proposed for UPt by Machida et al, shows that there exists a new
class of solutions carrying two units of magnetic flux: the magnetic skyrmion.
These solutions do not have singular core like Abrikosov vortices and at low
magnetic fields they become lighter for strongly type II superconductors.
Magnetic skyrmions repel each other as at distances much larger then the
magnetic penetration depth , forming a relatively robust triangular
lattice. The magnetic induction near is found to increase as
. This behavior agrees well with experiments.Comment: 4 pages, 2 figures, 2 column format; v2:misprint in the title is
correcte
Magnetic skyrmions and their lattices in triplet superconductors
Complete topological classification of solutions in SO(3) symmetric
Ginzburg-Landau free energy has been performed and a new class of solutions in
weak external magnetic field carrying two units of magnetic flux has been
identified. These solutions, magnetic skyrmions, do not have singular core like
Abrikosov vortices and at low magnetic field become lighter for strongly type
II superconductors. As a consequence, the lower critical magnetic field Hc1 is
reduced by a factor of log(kappa). Magnetic skyrmions repel each other as 1/r
at distances much larger then magnetic penetration depth forming relatively
robust triangular lattice. Magnetic induction near Hc1 increases gradually as
(H-Hc1)^2. This agrees very well with experiments on heavy fermion
superconductor UPt3. Newly discovered Ru based compounds Sr2RuO4 and
Sr2YRu(1-x)Cu(x)O6 are other possible candidates to possess skyrmion lattices.
Deviations from exact SO(3) symmetry are also studied.Comment: 23 pages, 10 eps figure
Nitrous Oxide Abatement Coupled with Biopolymer Production As a Model GHG Biorefinery for Cost-Effective Climate Change Mitigation
Producción CientÃficaN2O represents ∼6% of the global greenhouse gas emission inventory and the most important O3-depleting substance emitted in this 21st century. Despite its environmental relevance, little attention has been given to cost-effective and environmentally friendly N2O abatement methods. Here we examined, the potential of a bubble column (BCR) and an internal loop airlift (ALR) bioreactors of 2.3 L for the abatement of N2O from a nitric acid plant emission. The process was based on the biological reduction of N2O by Paracoccus denitrificans using methanol as a carbon/electron source. Two nitrogen limiting strategies were also tested for the coproduction of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) coupled with N2O reduction. High N2O removal efficiencies (REs) (≈87%) together with a low PHBV cell accumulation were observed in both bioreactors in excess of nitrogen. However, PHBV contents of 38–64% were recorded under N limiting conditions along with N2O-REs of ≈57% and ≈84% in the ALR and BCR, respectively. Fluorescence in situ hybridization analyses showed that P. denitrificans was dominant (>50%) after 6 months of experimentation. The successful abatement of N2O concomitant with PHBV accumulation confirmed the potential of integrating biorefinery concepts into biological gas treatment for a cost-effective GHG mitigation.Ministerio de EconomÃa, Industria y Competitividad (Proyect CTM2015-70442-R and Red NOVEDAR CTQ2014-51693-REDC
GAINS ASIA: Scenarios for cost-effective control of air pollution and greenhouse gases in India
There is growing recognition that a comprehensive and combined analysis of air pollution and climate change could reveal important synergies of emission control measures. Insight into the multiple benefits of measures could make emission controls economically more viable, both in industrialized and developing countries. However, while scientific understanding on many individual aspects of air pollution and climate change has considerably increased in the last years, little attention has been paid to a holistic analysis of the interactions between both problems.
The Greenhouse gas - Air pollution Interactions and Synergies (GAINS) model has been developed as a tool to identify emission control strategies that maximize synergies between the control of local air quality and the mitigation of greenhouse emissions. GAINS investigates how specific mitigation measures simultaneously influence different pollutants that threaten human health via the exposure of fine particles and ground-level ozone, damage natural vegetation and crops, contribute to climate change.
In recent years the GAINS model has been implemented for India in collaboration between the International Institute for Applied Systems Analysis (IIASA) and The Energy and Resources Institute (TERI). This report presents a first analysis conducted with the GAINS model that highlights how strategies to control local air quality could be designed in such a way that co-benefits on greenhouse gas mitigation could be maximized
Quasiperiodic spin-orbit motion and spin tunes in storage rings
We present an in-depth analysis of the concept of spin precession frequency
for integrable orbital motion in storage rings. Spin motion on the periodic
closed orbit of a storage ring can be analyzed in terms of the Floquet theorem
for equations of motion with periodic parameters and a spin precession
frequency emerges in a Floquet exponent as an additional frequency of the
system. To define a spin precession frequency on nonperiodic synchro-betatron
orbits we exploit the important concept of quasiperiodicity. This allows a
generalization of the Floquet theorem so that a spin precession frequency can
be defined in this case too. This frequency appears in a Floquet-like exponent
as an additional frequency in the system in analogy with the case of motion on
the closed orbit. These circumstances lead naturally to the definition of the
uniform precession rate and a definition of spin tune. A spin tune is a uniform
precession rate obtained when certain conditions are fulfilled. Having defined
spin tune we define spin-orbit resonance on synchro--betatron orbits and
examine its consequences. We give conditions for the existence of uniform
precession rates and spin tunes (e.g. where small divisors are controlled by
applying a Diophantine condition) and illustrate the various aspects of our
description with several examples. The formalism also suggests the use of
spectral analysis to ``measure'' spin tune during computer simulations of spin
motion on synchro-betatron orbits.Comment: 62 pages, 1 figure. A slight extension of the published versio
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Multimodal Brain Changes in First-Episode Mania: A Voxel-Based Morphometry, Functional Magnetic Resonance Imaging, and Connectivity Study
Background: Brain structural and functional changes in bipolar disorder (BD) are well-established findings, but it is uncertain whether these changes are already present in first episode mania (FEM).
Methods: We compared 31 FEM subjects, with 31 healthy individuals matched for age, sex, and premorbid IQ. Whole-brain voxel-wise morphometry, functional magnetic resonance imaging during the n-back task, and a functional connectivity analysis were performed.
Results: There were no volumetric differences between the 2 groups. During the 2-back task, FEM patients did not perform differently from controls and activated similar regions, but they showed less deactivation in the ventromedial prefrontal cortex (vmPFC), the anterior hub of the default mode network (DMN). They showed preserved functional connectivity between the vmPFC and other regions of the DMN, but increased connectivity with the superior frontal gyrus.
Conclusions: The absence of volumetric changes in FEM patients suggests that these changes could be related to progression of the illness. On the other hand, the failure of deactivation of the anterior hub of the DMN is present from the onset of the illness and may represent a core pathophysiological feature of BD
On the canonically invariant calculation of Maslov indices
After a short review of various ways to calculate the Maslov index appearing
in semiclassical Gutzwiller type trace formulae, we discuss a
coordinate-independent and canonically invariant formulation recently proposed
by A Sugita (2000, 2001). We give explicit formulae for its ingredients and
test them numerically for periodic orbits in several Hamiltonian systems with
mixed dynamics. We demonstrate how the Maslov indices and their ingredients can
be useful in the classification of periodic orbits in complicated bifurcation
scenarios, for instance in a novel sequence of seven orbits born out of a
tangent bifurcation in the H\'enon-Heiles system.Comment: LaTeX, 13 figures, 3 tables, submitted to J. Phys.
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