762 research outputs found
Adding species diversity to a reconstructed prairie using an incremental approach
Plant species diversity in reconstructed prairies is extremely low when compared to that of prairie remnants. In this experiment I am testing the feasibility of increasing the abundance of native forbs in a reconstructed prairie using an incremental approach. The site chosen for this experiment is one that consists of five species of thirty-year old prairie grasses along with 23 species of native prairie forbs that were overseeded in 1999.
I hypothesized that forb diversity could be increased in an established grassland using an incremental approach, and that mowing would amplify the success of the planting. To test these ideas I overseeded 10 species of native forbs into 18, 12m x 15m experimental plots at a rate of250 seeds/m2• Each plot was then randomly assigned one of three mowing treatments: control, infrequently mowed, and frequently mowed, which were carried out for two consecutive growing seasons. I assessed the effects of the different mowing treatments on both the new species I seeded in 2003, the adult forbs that were seeded in 1999, as well as, the effects on the overall plant community.
While mowing did significantly increase the amount of light reaching the soil surface (p=0.02), and reduce the amount of accumulated leaf litter (p
Mowing also had significant effects on the established plant community. Mowing significantly (p
The overall plant community changed greatly during the experimental period, but the changes were not due to the mowing treatments. Species richness increased in all the plots from approximately 0.5 species/m2 in 2003 to nearly one species/m2 by 2005. The Shannon diversity index also increased from 1.8 in 2003 to 2.15 in 2005.
Based on the results of this study, I have concluded that it is possible to add forb diversity to a reconstructed prairie using an incremental approach (seven new forb species became established at the site during this experiment), but mowing may not be necessary during the second incremental seeding. The increase in species richness achieved here proves this method is effective for making prairie reconstructions more similar to the actual tallgrass prairie
Improving and disaggregating N2O emission factors for ruminant excreta on temperate pasture soils
pre-printCattle excreta deposited on grazed grasslands are a major source of the greenhouse gas (GHG) nitrous oxide (N2O). Currently, many countries use the IPCC default emission factor (EF) of 2% to estimate excreta-derived N2O emissions. However, emissions can vary greatly depending on the type of excreta (dung or urine), soil type and timing of application. Therefore three experiments were conducted to quantify excreta-derived N2O emissions and their associated EFs, and to assess the effect of soil type, season of application and type of excreta on the magnitude of losses. Cattle dung, urine and artificial urine treatments were applied in spring, summer and autumn to three temperate grassland sites with varying soil and weather conditions. Nitrous oxide emissions were measured from the three experiments over 12 months to generate annual N2O emission factors. The EFs from urine treated soil was greater (0.30–4.81% for real urine and 0.13–3.82% for synthetic urine) when compared with dung (− 0.02–1.48%) treatments. Nitrous oxide emissions were driven by environmental conditions and could be predicted by rainfall and temperature before, and soil moisture deficit after application; highlighting the potential for a decision support tool to reduce N2O emissions by modifying grazing management based on these parameters. Emission factors varied seasonally with the highest EFs in autumn and were also dependent on soil type, with the lowest EFs observed from well-drained and the highest from imperfectly drained soil. The EFs averaged 0.31 and 1.18% for cattle dung and urine, respectively, both of which were considerably lower than the IPCC default value of 2%. These results support both lowering and disaggregating EFs by excreta type.This research was financially supported under the National Development Plan, through the Research Stimulus Fund, administered by the Department of Agriculture, Food and the Marine (Grant numbers RSF10/RD/SC/716 and 11S138)
Proteomic Insights into the Hidden World of Phloem Sap Feeding
The physical interface between a phloem-feeding insect and its host
plant is a single cell buried deep within the plant tissue. As such, the molecular
interactions between these notorious agricultural pests and the crop plants upon
which they feed are diffi cult to study. ‘Omic’ technologies have proved crucial in
revealing some of the fascinating detail of the molecular interplay between these
partners. Here we review the role of proteomics in identifying putative components
of the secreted saliva of phloem-feeding insects, particularly aphids, and discuss the
limited knowledge concerning the function of these proteins
Relative multiplexing for minimizing switching in linear-optical quantum computing
Many existing schemes for linear-optical quantum computing (LOQC) depend on
multiplexing (MUX), which uses dynamic routing to enable near-deterministic
gates and sources to be constructed using heralded, probabilistic primitives.
MUXing accounts for the overwhelming majority of active switching demands in
current LOQC architectures. In this manuscript, we introduce relative
multiplexing (RMUX), a general-purpose optimization which can dramatically
reduce the active switching requirements for MUX in LOQC, and thereby reduce
hardware complexity and energy consumption, as well as relaxing demands on
performance for various photonic components. We discuss the application of RMUX
to the generation of entangled states from probabilistic single-photon sources,
and argue that an order of magnitude improvement in the rate of generation of
Bell states can be achieved. In addition, we apply RMUX to the proposal for
percolation of a 3D cluster state in [PRL 115, 020502 (2015)], and we find that
RMUX allows a 2.4x increase in loss tolerance for this architecture.Comment: Published version, New Journal of Physics, Volume 19, June 201
The Role of Selective Attention in the Positivity Offset: Evidence from Event Related Potentials
Some research suggests that positive and negative valence stimuli may be processed differently. For example, negative material may capture and hold attention more readily than equally arousing positive material. This is called the negativity bias, and it has been observed as both behavioural and electroencephalographic (EEG) effects. Consequently, it has been attributed to both automatic and elaborative processes. However, at the lowest levels of arousal, faster reaction times and stronger EEG responses to positive material have been observed. This is called the positivity offset, and the underlying cognitive mechanism is less understood. To study the role of selective attention in the positivity offset, participants completed a negative affective priming (NAP) task modified to dissociate priming for positive and negative words. The task required participants to indicate the valence of a target word, while simultaneously ignoring a distractor. In experiment 1, a behavioural facilitation effect (faster response time) was observed for positive words, in stark contrast to the original NAP task. These results were congruent with a previously reported general categorization advantage for positive material. In experiment 2, participants performed the task while EEG was recorded. In additional to replicating the behavioural results from experiment 1, positive words elicited a larger Late Positive Potential (LPP) component on ignored repetition relative to control trials. Surprisingly, negative words elicited a larger LPP than positive words on control trials. These results suggest that the positivity offset may reflect a greater sensitivity to priming effects due to a more flexible attentional set
Standardising the collection of patient-reported experience measures to facilitate benchmarking and drive service improvement
Patient experience teams in NHS Wales’ Health Boards and Trusts are working across the country to collect patient experience feedback from members of the public who access health care services. Although this work is advanced in many areas, there is currently no way of benchmarking across organisations, reducing opportunities for shared learning. We aimed to work with patients and colleagues across Wales to agree a set of universal Patient Reported Experience Measures (PREMs) questions. Working with patient experience teams, patient groups and Welsh Government, the NHS Wales Patient Reported Outcome Measures (PROMs), Patient Reported Experience Measures (PREMs) and Effectiveness Programme team has agreed a national set of PREMs questions for use across Wales. This process led on from previous work and included patient focus groups, patient experience leads and clinical input. Patients using secondary care services in Wales will be invited to complete the agreed PREMs survey along with patient outcome measures, via an electronic platform. This will provide a consistent method of data collection which will allow us to benchmark across hospitals and organisations in NHS Wales, identifying areas of good practice, as well as areas where patients report poorer experiences. This will allow local patient experience teams to target more in-depth experience gathering initiatives and carry out appropriate improvement programmes, making better use of resources. Identifying and sharing good practice will allow NHS Wales to advance patient experience, while triangulation with patient and clinical outcomes will drive the Prudent Healthcare agenda
Maternal Psychological Absence and Toddlers' Social‐Emotional Development: Interpretations From the Perspective of Boundary Ambiguity Theory
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94745/1/famp1411.pd
Integrated Metabonomic-Proteomic Analysis of an Insect-Bacterial Symbiotic System
The health of animals, including humans, is dependent on their resident microbiota, but the complexity
of the microbial communities makes these associations difficult to study in most animals. Exceptionally,
the microbiology of the pea aphid Acyrthosiphon pisum is dominated by a single bacterium Buchnera
aphidicola (B. aphidicola). A 1H NMR-based metabonomic strategy was applied to investigate metabolic
profiles of aphids fed on a low essential amino acid diet and treated by antibiotic to eliminate B.
aphidicola. In addition, differential gel electrophoresis (DIGE) with mass spectrometry was utilized to
determine the alterations of proteins induced by these treatments. We found that these perturbations
resulted in significant changes to the abundance of 15 metabolites and 238 proteins. Ten (67%) of the
metabolites with altered abundance were amino acids, with nonessential amino acids increased and
essential amino acids decreased by both perturbations. Over-represented proteins in the perturbed
treatments included catabolic enzymes with roles in amino acid degradation and glycolysis, various
cuticular proteins, and a C-type lectin and regucalcin with candidate defensive roles. This analysis
demonstrates the central role of essential amino acid production in the relationship and identifies
candidate proteins and processes underpinning the function and persistence of the association
Genuine Counterfactual Communication with a Nanophotonic Processor
In standard communication information is carried by particles or waves.
Counterintuitively, in counterfactual communication particles and information
can travel in opposite directions. The quantum Zeno effect allows Bob to
transmit a message to Alice by encoding information in particles he never
interacts with. The first suggested protocol not only required thousands of
ideal optical components, but also resulted in a so-called "weak trace" of the
particles having travelled from Bob to Alice, calling the scalability and
counterfactuality of previous proposals and experiments into question. Here we
overcome these challenges, implementing a new protocol in a programmable
nanophotonic processor, based on reconfigurable silicon-on-insulator waveguides
that operate at telecom wavelengths. This, together with our telecom
single-photon source and highly-efficient superconducting nanowire
single-photon detectors, provides a versatile and stable platform for a
high-fidelity implementation of genuinely trace-free counterfactual
communication, allowing us to actively tune the number of steps in the Zeno
measurement, and achieve a bit error probability below 1%, with neither
post-selection nor a weak trace. Our demonstration shows how our programmable
nanophotonic processor could be applied to more complex counterfactual tasks
and quantum information protocols.Comment: 6 pages, 4 figure
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