886 research outputs found
Factors affecting performance of different pedigreed seedlots of Harrington barley and Katepwa wheat
Non-Peer Reviewe
Black Hole Interaction Energy
The interaction energy between two black holes at large separation distance
is calculated. The first term in the expansion corresponds to the Newtonian
interaction between the masses. The second term corresponds to the spin-spin
interaction. The calculation is based on the interaction energy defined on the
two black holes initial data. No test particle approximation is used. The
relation between this formula and cosmic censorship is discussed.Comment: 18 pages, 2 figures, LaTeX2
Subsoiling and surface tillage effects on soil physical properties and forage oat stand and yield
Much of New Zealand's agriculture integrates animal and crop production on poorly drained,
easily compacted soils. We hypothesized that soil properties affecting forage oat (Avena sativa,
cv Awapuni) establishment on land compacted by 15 years of conventional cropping might be
influenced by various subsoiling and surface tillage combinations. Plots on a Moutoa silty clay
(Typic Haplaquoil) were paraplowed (P), deep subsoiled (V), shallow subsoiled (5), or were left
as non-subsoiled controls (C). Subsequently, the surface 15 cm was surface-tilled (T) using a
power rotary-tiller and firmed with a Cambridge roller or were not tilled (N). Oats were then sown
with a cross-slot drill. Subsoiling greatly reduced soil strength. Cone indices showed disruption to
40cm with P, 36 cm for V, and 30 cm for S. Approximately 60% of profile cone indices to a depth
of 0.5 m from subsoiled treatments were less than 1.5 MPa, compared to approximately 30% for C.
T slightly improved strength distribution in non-subsoiled controls but had little effect in subsoiled
treatments. Subsoiling without T continued to show improved profile cone index cumulative
frequency 233 days after subsoiling, Subsoiling after T in this high rainfall climate eliminated
most of the separation in cumulative frequency of soil profile cone index values by two weeks
after T. T reduced emergence from 142 to 113 plants per square meter and reduced yield from
5318 to 3679 kg ha-1. Forage yield increased from 3974 to 4674 kg ha-1 with subsoiling. Soil
porosity, saturated and slightly unsaturated hydraulic conductivities (KSAT and K_40 ) and air
permeability were highly variable but generally increased with subsoiling. Oxygen diffusion rate
(ODR) (using Pt microelectrodes) was also variable, but N and C treatments had consistently
lower ODRs than T or subsoiled treatments. Generally, subsoiling without T produced better soil
conditions and oat crop performance than the prevailing New Zealand practice of T without subsoiling
Recommended from our members
Fish passage hydrodynamics New Zealand context
New Zealand is home to 57 native freshwater fish species, of which a considerable number are diadromous, having to move between freshwater and saltwater at least once during their lifecycle. The economic utilisation of New Zealand rivers has largely been carried out without fish migration behaviour in mind, resulting in thousands of structures that prevent fish migration up- and downriver. Remediation of existing structures, especially culverts, and construction of new, more fish friendly, structures requires in-depth knowledge of the needs of the target fish species. In April 2018, the New Zealand Fish Passage Guidelines were released, providing a design framework to enable fish passage in new and existing structures. In support of the new guidance, our project aims to gain insight into the swimming behaviour and performance of inanga (Galaxias maculatus) under various hydraulic conditions, in particular when swimming upstream, which is not well understood. For this purpose, we are designing a new experimental setup in a 600 mm wide flume at the Water Engineering Laboratory at the University of Auckland. We will study hydrodynamics of fish passes with roughened surfaces, baffles and energy dissipators. We will evaluate sensor equipment used to enable flow and fish tracking, with the intention of tracking individual inanga at critical cross sections. This will allow us to study fish response to turbulence, boundary layers, resting zones and wetted margins. We aim to gain valuable insight into design methods and materials that best help inanga, and potentially other members of the family Galaxiidae, with their migration. Eventually, the project aims to provide guidelines suitable for retrofitting existing and building new structures
Dimeric FcγR ectodomains detect pathogenic anti-platelet factor 4-heparin antibodies in heparin-induced thromobocytopenia
Background
Heparin‐induced thrombocytopenia (HIT) is a major and potentially fatal consequence of antibodies produced against platelet factor 4 (PF4)–heparin complexes following heparin exposure. Not all anti‐PF4–heparin antibodies are pathogenic, so overdiagnosis can occur, with resulting inappropriate use of alternative anticoagulation therapies that have associated risks of bleeding. However, definitive platelet functional assays are not widely available for routine analysis.
Objectives
To assess the utility of dimeric recombinant soluble FcγRIIa (rsFcγRIIa) ectodomains for detecting HIT antibodies.
Patients/Methods
Plasma from 27 suspected HIT patients were tested for pathogenic anti‐PF4–heparin antibodies by binding of a novel dimeric FcγRIIa ectodomain probe. Plasmas were also tested by the use of PF4–heparin IgG ELISA, the HemosIL AcuStar HIT IgG‐specific assay, and a serotonin release assay (SRA).
Results
The dimeric rsFcγRIIa test produced no false positives and excluded four samples that were positive by IgG ELISA. In this small patient cohort, the novel assay correctly assigned 93% of the suspected HIT patients, with two of the HIT patients being scored as false negatives. The improved discrimination of the novel assay over the IgG ELISA, which scored four false positives, supports the mechanistic interpretation that binding of dimeric rsFcγRIIa detects pairs of closely spaced IgG antibodies in PF4–heparin immune complexes.
Conclusions
This study found the cell‐free, function‐based dimeric rsFcγRIIa assay to be convenient, simple, and potentially predictive of HIT. The assay had improved specificity over the IgG ELISA, and correlated strongly with the AcuStar HIT IgG‐specific assay, warranting further evaluation of its potential to identify HIT in larger patient cohorts
The imposition of Cauchy data to the Teukolsky equation I: The nonrotating case
Gravitational perturbations about a Kerr black hole in the Newman-Penrose
formalism are concisely described by the Teukolsky equation. New numerical
methods for studying the evolution of such perturbations require not only the
construction of appropriate initial data to describe the collision of two
orbiting black holes, but also to know how such new data must be imposed into
the Teukolsky equation. In this paper we show how Cauchy data can be
incorporated explicitly into the Teukolsky equation for non-rotating black
holes. The Teukolsky function and its first time derivative
can be written in terms of only the 3-geometry and the
extrinsic curvature in a gauge invariant way. Taking a Laplace transform of the
Teukolsky equation incorporates initial data as a source term. We show that for
astrophysical data the straightforward Green function method leads to divergent
integrals that can be regularized like for the case of a source generated by a
particle coming from infinity.Comment: 9 pages, REVTEX. Misprints corrected in formulas (2.4)-(2.7). Final
version to appear in PR
Area Invariance of Apparent Horizons under Arbitrary Boosts
It is a well known analytic result in general relativity that the
2-dimensional area of the apparent horizon of a black hole remains invariant
regardless of the motion of the observer, and in fact is independent of the slice, which can be quite arbitrary in general relativity.
Nonetheless the explicit computation of horizon area is often substantially
more difficult in some frames (complicated by the coordinate form of the
metric), than in other frames. Here we give an explicit demonstration for very
restricted metric forms of (Schwarzschild and Kerr) vacuum black holes. In the
Kerr-Schild coordinate expression for these spacetimes they have an explicit
Lorentz-invariant form. We consider {\it boosted} versions with the black hole
moving through the coordinate system. Since these are stationary black hole
spacetimes, the apparent horizons are two dimensional cross sections of their
event horizons, so we compute the areas of apparent horizons in the boosted
space with (boosted) , and obtain the same result as in the
unboosted case. Note that while the invariance of area is generic, we deal only
with black holes in the Kerr-Schild form, and consider only one particularly
simple change of slicing which amounts to a boost. Even with these restrictions
we find that the results illuminate the physics of the horizon as a null
surface and provide a useful pedagogical tool. As far as we can determine, this
is the first explicit calculation of this type demonstrating the area
invariance of horizons. Further, these calculations are directly relevant to
transformations that arise in computational representation of moving black
holes. We present an application of this result to initial data for boosted
black holes.Comment: 19 pages, 3 figures. Added a new section and 2 plots along with a
coautho
A narrative review of patient and family engagement
Background: Patient and family engagement (PFE) is vital to the spirit of the medical home. This article reflects the efforts of an expert consensus panel, the Patient and Family Engagement Workgroup, as part of the Society of General Internal Medicine's 2013 Research Conference. Objective: To review extant literature on PFE in pediatric and adult medicine and quality improvement, highlight emerging best practices and models, suggest questions for future research, and provide references to tools and resources to facilitate implementation of PFE strategies. Methods: We conducted a narrative review of relevant articles published from 2000 to 2015. Additional information was retrieved from personal contact with experts and recommended sources from workgroup members. Results: Despite the theoretical importance of PFE and policy recommendations that PFE occurs at all levels across the health care system, evidence of effectiveness is limited, particularly for quality improvement. There is some evidence that PFE is effective, mostly related to engagement in the care of individual patients, but the evidence is mixed and few studies have assessed the effect of PFE on health outcomes. Measurement issues and the lack of a single comprehensive conceptual model pose challenges to progress in this field. Recommendations for future research and a list of practical tools and resources to facilitate PFE are provided. Conclusions: Although PFE appeals to patients, families, providers, and policy-makers, research is needed to assess outcomes beyond satisfaction, address implementation barriers, and support engagement in practice redesign and quality improvement. Partnering with patients and families has great potential to support high-quality health care and optimize outcomes
Comparing initial-data sets for binary black holes
We compare the results of constructing binary black hole initial data with
three different decompositions of the constraint equations of general
relativity. For each decomposition we compute the initial data using a
superposition of two Kerr-Schild black holes to fix the freely specifiable
data. We find that these initial-data sets differ significantly, with the ADM
energy varying by as much as 5% of the total mass. We find that all
initial-data sets currently used for evolutions might contain unphysical
gravitational radiation of the order of several percent of the total mass. This
is comparable to the amount of gravitational-wave energy observed during the
evolved collision. More astrophysically realistic initial data will require
more careful choices of the freely specifiable data and boundary conditions for
both the metric and extrinsic curvature. However, we find that the choice of
extrinsic curvature affects the resulting data sets more strongly than the
choice of conformal metric.Comment: 18 pages, 12 figures, accepted for publication in Phys. Rev.
Free Vibrations of Multilayer Anisotropic Cylindrical Shells
A theoretical analysis is presented for determining the free vibra tional characteristics of thin-walled, circular cylindrical shells with layers of anisotropic elastic material arbitrarily laminated either sym metrically or unsymmetrically about the shell middle surface. An arbitrarily laminated, anisotropic version of Love's first-approximation shell theory is used to formulate the coupled equations of motion. An exact solution with a classical checkerboard nodal pattern is found for the case of a shell with specially orthotropic layers arbitrarily laminated and with freely supported ends. For a boron/epoxy composite cylinder, the significant effect of omitting bending-stretching coupling is demonstrated and various lamination arrangements are investigated. Also, a general solution is presented for the axisymmetric modes of an arbitrarily laminated anisotropic shell. Finally, an approximate solution, using a combination of two helical-nodal-pattern modes, is obtained for the unsymmetric modes of the same general class of shell with a supported boundary condition.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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