Tree-based intercropping: a land use for greenhouse gas mitigation in canadian agricultural systems

PosterIn tree-based intercropping (TBI) systems, the potential influence of trees in relation to carbon (C ) sequestration and Greenhouse Gas (GHG) emissions reduction has been documented but the mechanisms, remain poorly understood, especially for below-ground processes. Recently, several studies in this area were undertaken in Ontario, Canada under the auspices of Canada’s involvement in the Global Research Alliance. C sequestration potential, nitrous oxide reduction potential and soil voids were quantified in a 25-year-old TBI system in southern Ontario for five tree species: hybrid poplar (Populus spp.), Norway spruce (Picae abies), red oak (Quercus rubra), black walnut (Juglans nigra), and white cedar (Thuja occidentalis) which were intercropped with soybean (Glycine max). Results were compared with a conventional agricultural system in which soybean was grown as the sole crop. The net C flux for poplar, spruce, oak, walnut, cedar and the soybean sole-crop were + 2.1, + 1.6, + 0.8, + 1.8, +1.4 and – 1.2 t C ha-1, y-1, respectively. The results suggest a greater atmospheric CO2 sequestration potential for all five tree species when compared to a conventional agricultural system. DNA was also extracted from soil cores collected around four of the tree species (walnut, red oak, Norway spruce, poplar) and used for quantitative real-time PCR to determine the abundance of key functional genes in the nitrification and denitrification pathways. Results indicate that both tree species and proximity to the tree, can influence the abundance of key microbial groups associated with N2O production, particularly organisms associated with denitrification, nosZ and nirS. Soil void analysis showed that there was a positive correlation between x-ray bulk radio-density and soil bulk density, and a negative correlation between mean intra-aggregate x-ray radio-density and soil organic carbon (rs=-0.48, p=0.033), suggesting that the X-ray CT method could therefore be used to predict these soil properties

Tree-based intercropping: a land use for greenhouse gas mitigation in canadian agricultural systems

PosterIn tree-based intercropping (TBI) systems, the potential influence of trees in relation to carbon (C ) sequestration and Greenhouse Gas (GHG) emissions reduction has been documented but the mechanisms, remain poorly understood, especially for below-ground processes. Recently, several studies in this area were undertaken in Ontario, Canada under the auspices of Canada’s involvement in the Global Research Alliance. C sequestration potential, nitrous oxide reduction potential and soil voids were quantified in a 25-year-old TBI system in southern Ontario for five tree species: hybrid poplar (Populus spp.), Norway spruce (Picae abies), red oak (Quercus rubra), black walnut (Juglans nigra), and white cedar (Thuja occidentalis) which were intercropped with soybean (Glycine max). Results were compared with a conventional agricultural system in which soybean was grown as the sole crop. The net C flux for poplar, spruce, oak, walnut, cedar and the soybean sole-crop were + 2.1, + 1.6, + 0.8, + 1.8, +1.4 and – 1.2 t C ha-1, y-1, respectively. The results suggest a greater atmospheric CO2 sequestration potential for all five tree species when compared to a conventional agricultural system. DNA was also extracted from soil cores collected around four of the tree species (walnut, red oak, Norway spruce, poplar) and used for quantitative real-time PCR to determine the abundance of key functional genes in the nitrification and denitrification pathways. Results indicate that both tree species and proximity to the tree, can influence the abundance of key microbial groups associated with N2O production, particularly organisms associated with denitrification, nosZ and nirS. Soil void analysis showed that there was a positive correlation between x-ray bulk radio-density and soil bulk density, and a negative correlation between mean intra-aggregate x-ray radio-density and soil organic carbon (rs=-0.48, p=0.033), suggesting that the X-ray CT method could therefore be used to predict these soil properties

Tree-based intercropping: a land use for greenhouse gas mitigation in canadian agricultural systems

PosterIn tree-based intercropping (TBI) systems, the potential influence of trees in relation to carbon (C ) sequestration and Greenhouse Gas (GHG) emissions reduction has been documented but the mechanisms, remain poorly understood, especially for below-ground processes. Recently, several studies in this area were undertaken in Ontario, Canada under the auspices of Canada’s involvement in the Global Research Alliance. C sequestration potential, nitrous oxide reduction potential and soil voids were quantified in a 25-year-old TBI system in southern Ontario for five tree species: hybrid poplar (Populus spp.), Norway spruce (Picae abies), red oak (Quercus rubra), black walnut (Juglans nigra), and white cedar (Thuja occidentalis) which were intercropped with soybean (Glycine max). Results were compared with a conventional agricultural system in which soybean was grown as the sole crop. The net C flux for poplar, spruce, oak, walnut, cedar and the soybean sole-crop were + 2.1, + 1.6, + 0.8, + 1.8, +1.4 and – 1.2 t C ha-1, y-1, respectively. The results suggest a greater atmospheric CO2 sequestration potential for all five tree species when compared to a conventional agricultural system. DNA was also extracted from soil cores collected around four of the tree species (walnut, red oak, Norway spruce, poplar) and used for quantitative real-time PCR to determine the abundance of key functional genes in the nitrification and denitrification pathways. Results indicate that both tree species and proximity to the tree, can influence the abundance of key microbial groups associated with N2O production, particularly organisms associated with denitrification, nosZ and nirS. Soil void analysis showed that there was a positive correlation between x-ray bulk radio-density and soil bulk density, and a negative correlation between mean intra-aggregate x-ray radio-density and soil organic carbon (rs=-0.48, p=0.033), suggesting that the X-ray CT method could therefore be used to predict these soil properties

Quantum phase transition in a two-channel-Kondo quantum dot device

We develop a theory of electron transport in a double quantum dot device recently proposed for the observation of the two-channel Kondo effect. Our theory provides a strategy for tuning the device to the non-Fermi-liquid fixed point, which is a quantum critical point in the space of device parameters. We explore the corresponding quantum phase transition, and make explicit predictions for behavior of the differential conductance in the vicinity of the quantum critical point

Lower limb stiffness estimation during running: the effect of using kinematic constraints in muscle force optimization algorithms

The focus of this paper is on the effect of muscle force optimization algorithms on the human lower limb stiffness estimation. By using a forward dynamic neuromusculoskeletal model coupled with a muscle short-range stiffness model we computed the human joint stiffness of the lower limb during running. The joint stiffness values are calculated using two different muscle force optimization procedures, namely: Toque-based and Torque/Kinematic-based algorithm. A comparison between the processed EMG signal and the corresponding estimated muscle forces with the two optimization algorithms is provided. We found that the two stiffness estimates are strongly influenced by the adopted algorithm. We observed different magnitude and timing of both the estimated muscle forces and joint stiffness time profile with respect to each gait phase, as function of the optimization algorithm used

Communicating the uncertainty in estimated greenhouse gas emissions from agriculture

In an effort to mitigate anthropogenic effects on the global climate system, industrialised countries are required to quantify and report, for various economic sectors, the annual emissions of greenhouse gases from their several sources and the absorption of the same in different sinks. These estimates are uncertain, and this uncertainty must be communicated effectively, if government bodies, research scientists or members of the public are to draw sound conclusions. Our interest is in communicating the uncertainty in estimates of greenhouse gas emissions from agriculture to those who might directly use the results from the inventory. We tested six methods of communication. These were: a verbal scale using the IPCC calibrated phrases such as ‘likely’ and ‘very unlikely’; probabilities that emissions are within a defined range of values; confidence intervals for the expected value; histograms; box plots; and shaded arrays that depict the probability density of the uncertain quantity. In a formal trial we used these methods to communicate uncertainty about four specific inferences about greenhouse gas emissions in the UK. Sixty four individuals who use results from the greenhouse gas inventory professionally participated in the trial, and we tested how effectively the uncertainty about these inferences was communicated by means of a questionnaire. Our results showed differences in the efficacy of the methods of communication, and interactions with the nature of the target audience. We found that, although the verbal scale was thought to be a good method of communication it did not convey enough information and was open to misinterpretation. Shaded arrays were similarly criticised for being open to misinterpretation, but proved to give the best impression of uncertainty when participants were asked to interpret results from the greenhouse gas inventory. Box plots were most favoured by our participants largely because they were particularly favoured by those who worked in research or had a stronger mathematical background. We propose a combination of methods should be used to convey uncertainty in emissions and that this combination should be tailored to the professional grou

Quantum coherence in a degenerate two-level atomic ensemble: for a transition Fe=0↔Fg=1F_e=0\leftrightarrow F_g=1

For a transition $F_e=0\leftrightarrow F_g=1$ driven by a linearly polarized light and probed by a circularly light, quantum coherence effects are investigated. Due to the coherence between the drive Rabi frequency and Zeeman splitting, electromagnetically induced transparency, electromagnetically induced absorption, and the transition from positive to negative dispersion are obtained, as well as the populations coherently oscillating in a wide spectral region. At the zero pump-probe detuning, the subluminal and superluminal light propagation is predicted. Finally, coherent population trapping states are not highly sensitive to the refraction and absorption in such ensemble.Comment: 9 pages, 6 figure

Induced QCD and Hidden Local ZN Symmetry

We show that a lattice model for induced lattice QCD which was recently proposed by Kazakov and Migdal has a $Z_N$ gauge symmetry which, in the strong coupling phase, results in a local confinement where only color singlets are allowed to propagate along links and all Wilson loops for non-singlets average to zero. We argue that, if this model is to give QCD in its continuum limit, it must have a phase transition. We give arguments to support presence of such a phase transition

Phase transitions in BaTiO3_3 from first principles

We develop a first-principles scheme to study ferroelectric phase transitions for perovskite compounds. We obtain an effective Hamiltonian which is fully specified by first-principles ultra-soft pseudopotential calculations. This approach is applied to BaTiO$_3$, and the resulting Hamiltonian is studied using Monte Carlo simulations. The calculated phase sequence, transition temperatures, latent heats, and spontaneous polarizations are all in good agreement with experiment. The order-disorder vs.\ displacive character of the transitions and the roles played by different interactions are discussed.Comment: 13 page

Experimental feasibility of measuring the gravitational redshift of light using dispersion in optical fibers

This paper describes a new class of experiments that use dispersion in optical fibers to convert the gravitational frequency shift of light into a measurable phase shift or time delay. Two conceptual models are explored. In the first model, long counter-propagating pulses are used in a vertical fiber optic Sagnac interferometer. The second model uses optical solitons in vertically separated fiber optic storage rings. We discuss the feasibility of using such an instrument to make a high precision measurement of the gravitational frequency shift of light.Comment: 11 pages, 12 figure