43,386 research outputs found
Flight testing the fixed-wing configuration of the Rotor Systems Research Aircraft (RSRA)
The Rotor Systems Research Aircraft (RSRA) is a unique research aircraft designed to flight test advanced helicopter rotor system. Its principal flight test configuration is as a compound helicopter. The fixed wing configuration of the RSRA was primarily considered an energy fly-home mode in the event it became necessary to sever an unstable rotor system in flight. While it had always been planned to flight test the fixed wing configuration, the selection of the RSRA as the flight test bed for the X-wing rotor accelerated this schedule. This paper discusses the build-up to, and the test of, the RSRA fixed wing configuration. It is written primarily from the test pilot's perspective
Web-based Tools for the Analysis of DNA Microarrays
End of project reportDNA microarrays are widely used for gene expression profiling. Raw data resulting from microarray experiments, however, tends to be very noisy and there are many sources of technical variation and bias. This raw data needs to be quality assessed and interactively preprocessed to minimise variation before statistical analysis in order to achieve meaningful result. Therefore microarray analysis requires a combination of visualisation and statistical tools, which vary depending on what microarray platform or experimental design is used.Bioconductor is an existing open source software project that attempts to facilitate
analysis of genomic data. It is a collection of packages for the statistical programming
language R. Bioconductor is particularly useful in analyzing microarray experiments. The
problem is that the R programming languageâs command line interface is intimidating to
many users who do not have a strong background in computing. This often leads to a
situation where biologists will resort to using commercial software which often uses
antiquated and much less effective statistical techniques, as well as being expensively
priced. This project aims to bridge this gap by providing a user friendly web-based
interface to the cutting edge statistical techniques of Bioconductor
Lie symmetries of (1+2) nonautonomous evolution equations in Financial Mathematics
We analyse two classes of evolution equations which are of special
interest in Financial Mathematics, namely the Two-dimensional Black-Scholes
Equation and the equation for the Two-factor Commodities Problem. Our approach
is that of Lie Symmetry Analysis. We study these equations for the case in
which they are autonomous and for the case in which the parameters of the
equations are unspecified functions of time. For the autonomous Black-Scholes
Equation we find that the symmetry is maximal and so the equation is reducible
to the Classical Heat Equation. This is not the case for the
nonautonomous equation for which the number of symmetries is submaximal. In the
case of the two-factor equation the number of symmetries is submaximal in both
autonomous and nonautonomous cases. When the solution symmetries are used to
reduce each equation to a equation, the resulting equation is of
maximal symmetry and so equivalent to the Classical Heat Equation.Comment: 15 pages, 1 figure, to be published in Mathematics in the Special
issue "Mathematical Finance
Excitation of the molecular gas in the nuclear region of M82
We present high-resolution HIFI spectroscopy of the nucleus of the archetypical starburst galaxy Mâ82. Six ^(12)COâlines, 2 ^(13)COâlines and 4 fine-structure lines have been detected. Besides showing the effects of the overall velocity structure of the nuclear region, the line profiles also indicate the presence of multiple components with different optical depths, temperatures, and densities in the observing beam. The data have been interpreted using a grid of PDR models. It is found that the majority of the molecular gas is in low density (n = 10^(3.5) cm^(-3)) clouds, with column densities of N_H = 10^(21.5) cm^(-2) and a relatively low UV radiation field (G_0 = 10^2). The remaining gas is predominantly found in clouds with higher densities (n = 10^5 cm^(-3)) and radiation fields (G_0 = 10^(2.75)), but somewhat lower column densities (N_H = 10^(21.2) cm^(-2)). The highest J CO lines are dominated by a small (1% relative surface filling) component, with an even higher density (n = 10^6 cm^(-3)) and UV field (G_0 = 10^(3.25)). These results show the strength of multi-component modelling for interpretating the integrated properties of galaxies
Microarray sub-grid detection: A novel algorithm
This is the post print version of the article. The official published version can be obtained from the link below - Copyright 2007 Taylor & Francis LtdA novel algorithm for detecting microarray subgrids is proposed. The only input to the algorithm is the raw microarray image, which can be of any resolution, and the subgrid detection is performed with no prior assumptions. The algorithm consists of a series of methods of spot shape detection, spot filtering, spot spacing estimation, and subgrid shape detection. It is shown to be able to divide images of varying quality into subgrid regions with no manual interaction. The algorithm is robust against high levels of noise and high percentages of poorly expressed or missing spots. In addition, it is proved to be effective in locating regular groupings of primitives in a set of non-microarray images, suggesting potential application in the general area of image processing
Global gene expression in endometrium of high and low fertility heifers during the mid-luteal phase of the estrous cycle
peer-reviewedBackground
In both beef and dairy cattle, the majority of early embryo loss occurs within the first 14Â days following insemination. During this time-period, embryos are completely dependent on their maternal uterine environment for development, growth and ultimately survival, therefore an optimum uterine environment is critical to their survival. The objective of this study was to investigate whether differences in endometrial gene expression during the mid-luteal phase of the estrous cycle exist between crossbred beef heifers ranked as either high (HF) or low fertility (LF) (following four rounds of artificial insemination (AI)) using the AffymetrixÂź 23Â K Bovine Gene Chip.
Results
Conception rates for each of the four rounds of AI were within a normal range: 70â73.3%. Microarray analysis of endometrial tissue collected on day 7 of the estrous cycle detected 419 differentially expressed genes (DEG) between HF (nâ=â6) and LF (nâ=â6) animals. The main gene pathways affected were, cellular growth and proliferation, angiogenesis, lipid metabolism, cellular and tissue morphology and development, inflammation and metabolic exchange. DEG included, FST, SLC45A2, MMP19, FADS1 and GALNT6.
Conclusions
This study highlights, some of the molecular mechanisms potentially controlling uterine endometrial function during the mid-luteal phase of the estrous cycle, which may contribute to uterine endometrial mediated impaired fertility in cattle. Differentially expressed genes are potential candidate genes for the identification of genetic variation influencing cow fertility, which may be incorporated into future breeding programmes.Teagasc Walsh Fellowship Programm
Forging, textures, and deformation systems in a B2 FeAl alloy
High-temperature forging experiments have been carried out by axial compression testing on a Fe-41Al-2Cr alloy in order to determine the deformation systems operating under such high-speed, high-temperature conditions, and to examine the textures produced by such deformation and during subsequent annealing to recrystallize. Deformation is deduced to take place by the operation of ă111ă {110} and ă111ă{112} slip systems at low temperatures and by ă100ă{001} and ă100ă{011} slip systems at high temperatures, with the formation of the expected strong ă111ă textures. The examination of the weak ă100ă texture component is critical to distinguishing the operating slip system. Both texture and dislocation analyses are consistent with the operation of these deformation systems. Recrystallization takes place extremely quickly at high temperatures (above 800 °C), that is within seconds after deformation and also dynamically during deformation itself. Recrystallization changes the texture such that ă100ă textures superimpose on the deformation texture. The flow stress peak observed during forging is found at a very high temperature. Possible origins of the peak are examined in terms of the operating slip system
Transition to turbulence in particulate pipe flow
We investigate experimentally the influence of suspended particles on the
transition to turbulence. The particles are monodisperse and neutrally-buoyant
with the liquid. The role of the particles on the transition depends both upon
the pipe to particle diameter ratios and the concentration. For large
pipe-to-particle diameter ratios the transition is delayed while it is lowered
for small ratios. A scaling is proposed to collapse the departure from the
critical Reynolds number for pure fluid as a function of concentration into a
single master curve.Comment: 4 pages, 4 figure
Possible Wormhole Solutions in (4+1) Gravity
We extend previous analyses of soliton solutions in (4+1) gravity to new
ranges of their defining parameters. The geometry, as studied using invariants,
has the topology of wormholes found in (3+1) gravity. In the induced-matter
picture, the fluid does not satisfy the strong energy conditions, but its
gravitational mass is positive. We infer the possible existance of (4+1)
wormholes which, compared to their (3+1) counterparts, are less exotic.Comment: 3 pages, latex, 1 figure
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