Differences in soil microbial communities in organic and conventional management systems alter soil nutrient dynamics

Non-Peer Reviewe

IDENTIFICATION OF NONLINEARITIES IN AN 8-DOF SYSTEM THROUGH SPECTRAL FEEDBACK

The accurate detection and characterization of nonlinearities associated with damage in structural systems is an area of vibration analysis that is being widely researched. In this paper, nonlinear behavior is considered a potential indicator of damage. Most conventional damage detection methods, such as those based on resonant frequencies and mode shapes, do not accurately identify the location and extent of nonlinearities present in a given structural system. As an extension of previous work at LANL, an effort is made to validate a damage detection method proposed by Adams. This method states that the frequency response function (FRF) matrix obtained from a low-level vibration test approximates the underlying linear FRF matrix of the system. The nonlinear systems' responses to high level excitation are combined with the linear FRF in a classic feedback loop to obtain the contributions of nonlinear internal forces. The temporal and spatial characteristics of the nonlinearities present in a structural system are identified. An 8-DOF system is used as a test case to validate the aforementioned method. Results of the tests and important issues concerning the method are presented

Nitrogen cycling in root associated soils at bolting, flowering and seed pod filling across eight diverse Brassica napus (canola) genotypes

Non-Peer ReviewedNitrogen (N) mineralization and nitrification can be used predict the amount of N that is available to crops. Brassica napus L. (canola) production is N intensive; therefore, to improve and sustain yields, a better understanding of N cycling patterns for fertilization application is needed. The objective of this study is to examine N cycling after urea fertilization at the three major canola growth stages: bolting, flowering and seed pod filling; and how N cycling may differ between diverse canola lines grown in different soil types. Eight diverse B. napus lines were grown on Dark Brown Chernozemic soil and Black Chernozemic soil in Saskatchewan, Canada. Root-associated soils were collected from each line at bolting, flowering and seed pod filling, and this soil was analyzed for potential nitrification and mineralization, as well as soil nitrate and ammonium content. We predict that potential nitrification will be higher during the bolting and flowering stages of canola growth because the urea fertilizer that was applied to the field would have been converted to nitrate-N, which is plant available. We predict that potential mineralization will be higher during flowering and seed pod filling, because the demand for N to make protein-rich seeds is high enough to deplete much of the inorganic fertilizer N. We also predict that both nitrate-N and ammonium-N will decrease over the growing season, with significant differences between the canola lines and the soil environments. Mixed effect analyses and ANOVA will be used to analyze N cycling in the soil in relation to soil type differences, canola line differences, and growth stage differences. By characterizing soil N processes, this research will advance efforts to understand and improve N uptake for B. napus lines

Microbial Metropolis: Understanding how legume pasture systems interact with soil microbial communities, and subsequent greenhouse gas emissions

Non-Peer ReviewedCattle producers may graze animals on mixed pastures of non-bloat legumes and grasses. This approach can increase dietary protein uptake, improve animal value, and reduce cattle methane emissions by decreasing pasture bloat. The introduction of legumes to a grass pasture can also affect greenhouse gas (GHG) fluxes from the soil by shifting the structure of the microbial communities responsible for nitrous oxide (N2O) emissions and methane consumption, and by altering mineralization rates and soil nutrient content. Two novel forage legume-grass mixes and a grass-alfalfa control were sampled throughout the 2017 and 2018 grazing seasons and analyzed for microbial community structure, nutrient cycling rates, as well as for N2O and methane GHG fluxes. Results suggest microbial community structure, rather than microbial abundance, as one factor regulating GHG emissions. Reduced phosphorous and nitrogen supply rates were key factors limiting microbial abundance, and communities experiencing these environmental stressors were correlated with reduced N2O fluxes. Increasing microbial abundance in response to substrate availability results in depletion of soil phosphorous and nitrogen. This in turn upregulates the carbon and nitrogen cycling activities of communities. Nitrogen and soil moisture content were correlated with increasing nitrous oxide emissions, suggesting that denitrification processes are the major contributor to pasture N2O emissions. In addition, decreasing moisture increased methane consumption, providing a partial sink for cattle-derived methane emissions. Sainfoin treatments had lower cumulative methane consumption when compared to cicer milkvetch and control treatments. Further analysis suggests that different interactions between environmental factors may be involved in shaping microbial communities within each legume treatment, and that local environmental conditions at each sampling point were more important than plant cover treatments in determining daily GHG fluxes. Understanding the microbial processes at play when considering net GHG emissions within a pasture system will contribute to the future sustainability of beef production systems

Legume based pasture rejuvenation for greenhouse gas outcomes

Non-Peer ReviewedIncorporating legumes into a grass based pasture system has multiple benefits. A grass/legume blend increases the dietary protein of foraging cattle over grass alone. Furthermore, symbiotic biological nitrogen fixation introduces additional nitrogen to the pasture system thereby potentially lessening the need for synthetic fertilizers. However, over time, pastures initially seeded with a blend of grasses and legumes will tend towards increasing grass dominance such that the presence and benefits of legumes diminishes. Reestablishing legumes on a mature pasture can restore these important functions. By improving ruminant diet and therefore feed conversion ratios as well as decreasing nitrogen fertilizer applications, pasture rejuvenation, through the introduction of legumes, is expected to lower the greenhouse gas cost of grazing livestock on a per output basis. However, disturbance of soils, which can be part of various rejuvenation techniques, can result in losses of soil carbon thereby offsetting potential at least some of the greenhouse gas benefits. Sod-seeding may be an effective strategy to establish legumes in a mature pasture thereby incurring benefits without heavily disrupting soils and incurring soil carbon loss. To test this, a multiyear experiment, including cattle, vegetation (specifically the incorporation of non-bloat legumes: cicer milkvetch and sainfoin), soils and microbiota, was established near Lanigan, SK to examine the impact of sod-seeded legume pasture rejuvenation on greenhouse gases

Dynamics of root-associated fungal community of canola genotypes in Saskatchewan soils

Non-Peer Reviewe

Beneficial plant-microbial interactions in agroecosystems: deciphering the rhizosphere microbial community in two field grown crops

Non-Peer Reviewe

Active positioning device for a perimodiolar cochlear electrode array

The authors report on an actuated positioning device for a cochlear prosthesis insertion procedure. The device consists of multiple high-aspect ratio fluidic actuator chambers integrated with a high-density silicon cochlear electrode array and manufactured in a tapered-helix form. Actuation chambers with cross-sectional sizes as small as 40 × 200 μm and lengths of 30 mm have been fabricated using flexible polymers. The device will allow for low-resistance basilar insertion of a stimulating electrode array into the cochlea providing for deep, perimodiolar position considered most beneficial for auditory nerve stimulation, while minimizing intracochlear trauma. Experimental measurements, FEA analysis, and modeling demonstrate a viable and appropriate actuation method for a cochlear implant procedure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47852/1/542_2004_Article_376.pd

The effects of financialisation and financial development on investment: Evidence from firm-level data in Europe

In this paper we estimate the effects of financialization on physical investment in selected western European countries using panel data based on the balance-sheets of publicly listed non-financial companies (NFCs) supplied by Worldscope for the period 1995-2015. We find robust evidence of an adverse effect of both financial payments (interests and dividends) and financial incomes on investment in fixed assets by the NFCs. This finding is robust for both the pool of all Western European firms and single country estimations. The negative impacts of financial incomes are non-linear with respect to the companies’ size: financial incomes crowd-out investment in large companies, and have a positive effect on the investment of only small, relatively more credit-constrained companies. Moreover, we find that a higher degree of financial development is associated with a stronger negative effect of financial incomes on companies’ investment. This finding challenges the common wisdom on ‘finance-growth nexus’. Our findings support the ‘financialization thesis’ that the increasing orientation of the non-financial sector towards financial activities is ultimately leading to lower physical investment, hence to stagnant or fragile growth, as well as long term stagnation in productivity