14,597 research outputs found
Effects of past and current crop management on leaching losses, soil microbial community composition and activity
A lysimeter experiment was conducted to investigate the effect of past and current management practices on soil microbial biomass, activity and community composition. Intact monolith lysimeters were taken from sites of the same soil type that had been under long-term organic and conventional crop management. They were subjected to the same crop rotation and managed according to best organic and conventional practices. Mineral N loss was determined in leachates and soil samples taken before the experiment and after 30 months were analysed for biological soil properties, including microbial diversity. Results indicated that leaching losses were similar for all treatments and that crop was the main influence on microbial biomass composition and size, while microbial activity was determined by management history
Protocol for electrophysiological monitoring of carotid endarterectomies.
Near zero stroke rates can be achieved in carotid endarterectomy (CEA) surgery with selective shunting and electrophysiological neuromonitoring. though false negative rates as high as 40% have been reported. We sought to determine if improved training for interpretation of the monitoring signals can advance the efficacy of selective shunting with electrophysiological monitoring across multiple centers, and determine if other factors could contribute to the differences in reports. Processed and raw beta band (12.5-30 Hz) electroencephalogram (EEG) and median and tibial nerve somatosensory evoked potentials (SSEP) were monitored in 668 CEA cases at six surgical centers. A decrease in amplitude of 50% or more in any EEG or SSEP channel was the criteria for shunting or initiating a neuroprotective protocol. A reduction of 50% or greater in the beta band of the EEG or amplitude of the SSEP was observed in 150 cases. No patient showed signs of a cerebral infarct after surgery. Selective shunting based on EEG and SSEP monitoring can reduce CEA intraoperative stroke rate to a near zero level if trained personnel adopted standardized protocols. We also found that the rapid administration of a protective stroke protocol by attending anesthesiologists was an important aspect of this success rate
Environmental research on the new Lincoln University dairy farm
A major challenge to the New Zealandās growing dairy industry is to achieve an annual
productivity gain of 4% in order to remain internationally competitive. However, it is important
to ensure that this productivity gain is achieved without significantly comprising the quality and
integrity of New Zealandās āclean and greenā environment.
There is increasing public concern about the effects of dairying on the environment, both
within New Zealand and by our overseas customers. One of the main concerns is the possible
threat to the quality of groundwater and surface water, particularly by nitrate, phosphate and
microbial contaminants.
Nitrate leaching from soil is of concern because of its impact on drinking water quality
and the effects that nitrate can have on rivers and lakes. A high nitrate concentration in drinking
water is a recognised health hazard and a high concentration in rivers and lakes can cause
excessive growth of algae and weeds, which may reduce the fish population. Nitrate leaching
also represents a financial cost to the farmer and a loss in soil fertility.
The establishment of the new Lincoln University dairy farm is designed to enable us to
develop and test practical methods to improve productivity and at the same time protect the
environment.
The objective of the environmental project on the new Lincoln University dairy farm is to
develop best management practices under irrigation which will ensure that the dairy
industryās 4% productivity gain is achieved in a sustainable way, and that the wider
environment is protected
Nutrient management on the Lincoln University dairy farm: "nutrient budgeting for efficient production"
Nutrient management plays an important role in any dairy farming system. Soil fertility
status and fertiliser inputs are key drivers of pasture and animal production, whilst fertiliser
represents a significant annual cost to the farm. At the same time, intensive agricultural systems
also face the challenge of minimising or reducing nutrient loss in order to maintain
environmental quality. Therefore 'best practice' may involve nutrient management in terms of
balancing production, economic, environmental and efficiency goals. With ever increasing
regulation and compliance requirements for the New Zealand farmer, best practice nutrient
management will play an increasingly important role in achieving long term sustainability of the
farming system.
This paper gives an overview of the use of nutrient budgeting as a method of effective
and efficient on-farm nutrient management. The paper will focus on nutrient management on
the Lincoln University Dairy Farm (LUDF), including soil fertility monitoring and targets, the
decision making process and the use of the nutrient budget output. Aspects of environmental
research on the LUDF will also be discussed, including the quantification of nitrogen (N) losses,
and results from research into nitrogen loss mitigation technology (eco-n nitrification inhibitor)
Re-embedding a 1-Plane Graph into a Straight-line Drawing in Linear Time
Thomassen characterized some 1-plane embedding as the forbidden configuration
such that a given 1-plane embedding of a graph is drawable in straight-lines if
and only if it does not contain the configuration [C. Thomassen, Rectilinear
drawings of graphs, J. Graph Theory, 10(3), 335-341, 1988].
In this paper, we characterize some 1-plane embedding as the forbidden
configuration such that a given 1-plane embedding of a graph can be re-embedded
into a straight-line drawable 1-plane embedding of the same graph if and only
if it does not contain the configuration. Re-embedding of a 1-plane embedding
preserves the same set of pairs of crossing edges.
We give a linear-time algorithm for finding a straight-line drawable 1-plane
re-embedding or the forbidden configuration.Comment: Appears in the Proceedings of the 24th International Symposium on
Graph Drawing and Network Visualization (GD 2016). This is an extended
abstract. For a full version of this paper, see Hong S-H, Nagamochi H.:
Re-embedding a 1-Plane Graph into a Straight-line Drawing in Linear Time,
Technical Report TR 2016-002, Department of Applied Mathematics and Physics,
Kyoto University (2016
3D Visibility Representations of 1-planar Graphs
We prove that every 1-planar graph G has a z-parallel visibility
representation, i.e., a 3D visibility representation in which the vertices are
isothetic disjoint rectangles parallel to the xy-plane, and the edges are
unobstructed z-parallel visibilities between pairs of rectangles. In addition,
the constructed representation is such that there is a plane that intersects
all the rectangles, and this intersection defines a bar 1-visibility
representation of G.Comment: Appears in the Proceedings of the 25th International Symposium on
Graph Drawing and Network Visualization (GD 2017
Recognizing and Drawing IC-planar Graphs
IC-planar graphs are those graphs that admit a drawing where no two crossed
edges share an end-vertex and each edge is crossed at most once. They are a
proper subfamily of the 1-planar graphs. Given an embedded IC-planar graph
with vertices, we present an -time algorithm that computes a
straight-line drawing of in quadratic area, and an -time algorithm
that computes a straight-line drawing of with right-angle crossings in
exponential area. Both these area requirements are worst-case optimal. We also
show that it is NP-complete to test IC-planarity both in the general case and
in the case in which a rotation system is fixed for the input graph.
Furthermore, we describe a polynomial-time algorithm to test whether a set of
matching edges can be added to a triangulated planar graph such that the
resulting graph is IC-planar
Tunable control of the bandwidth and frequency correlations of entangled photons
We demonstrate experimentally a new technique to control the bandwidth and
the type of frequency correlations (correlation, anticorrelation, and even
uncorrelation) of entangled photons generated by spontaneous parametric
downconversion. The method is based on the control of the group velocities of
the interacting waves. This technique can be applied in any nonlinear medium
and frequency band of interest. It is also demonstrated that this technique
helps enhance the quality of polarization entanglement even when femtosecond
pulses are used as a pump.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let
A review of ammonia-oxidizing bacteria and archaea in Chinese soils
Ammonia (NH3) oxidation, the first and rate-limiting step of nitrification, is a key step in the global Nitrogen (N) cycle. Major advances have been made in recent years in our knowledge and understanding of the microbial communities involved ammonia oxidation in a wide range of habitats, including Chinese agricultural soils. In this mini-review, we focus our attention on the distribution and community diversity of ammonia-oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA) in Chinese soils with variable soil properties and soil management practices. The niche differentiation of AOB and AOA in contrasting soils have been functionally demonstrated using DNA-SIP (stable isotope probing) methods, which have shown that AOA dominate nitrification processes in acidic soils, while AOB dominated in neutral, alkaline and N-rich soils. Finally, we discuss the composition and activity of ammonia oxidizer in paddy soils, as well as the mitigation of the greenhouse gas nitrous oxide (N2O) emissions and nitrate leaching via inhibition of nitrification by both AOB and AOA
Membrane capacitive deionisation as an alternative to the 2nd pass for seawater reverse osmosis desalination plant for bromide removal
Ā© 2018 Elsevier B.V. Most Australian surface and ground waters have relatively high concentration of bromide between 400 and 8000 Ī¼g/L and even higher concentration in seawater between 60,000ā78,000 Ī¼g/L. Although bromide is not regulated, even at low concentrations of 50ā100 Ī¼g/L, it can lead to the formation of several types of harmful disinfection by-products (DBPs) during the disinfection process. One of the major concerns with brominated DBPs is the formation of bromate (BrO3ā), a serious carcinogen that is formed when water containing a high concentration of bromide is disinfected. As a result, bromate is highly regulated in Australian water standards with the maximum concentration of 20 Ī¼g/L in the drinking water. Since seawater reverse osmosis (SWRO) desalination plays an important role in augmenting fresh water supplies in Australia, SWRO plants in Australia usually adopt 2nd pass brackish water reverse osmosis (BWRO) for effective bromide removal, which is not only energy-intensive to operate but also has higher capital cost. In this study, we evaluated the feasibility of membrane capacitive deionisation (MCDI) as one of the alternatives to the 2nd pass BWRO for effective bromide removal in a more energy efficient way
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