745 research outputs found
The POINT-AGAPE survey II: An Unrestricted Search for Microlensing Events towards M31
An automated search is carried out for microlensing events using a catalogue
of 44554 variable superpixel lightcurves derived from our three-year monitoring
program of M31. Each step of our candidate selection is objective and
reproducible by a computer. Our search is unrestricted, in the sense that it
has no explicit timescale cut. So, it must overcome the awkward problem of
distinguishing long-timescale microlensing events from long-period stellar
variables. The basis of the selection algorithm is the fitting of the
superpixel lightcurves to two different theoretical models, using variable star
and blended microlensing templates. Only if microlensing is preferred is an
event retained as a possible candidate. Further cuts are made with regard to
(i) sampling, (ii) goodness of fit of the peak to a Paczynski curve, (iii)
consistency of the microlensing hypothesis with the absence of a resolved
source, (iv) achromaticity, (v) position in the colour-magnitude diagram and
(vi) signal-to-noise ratio. Our results are reported in terms of first-level
candidates, which are the most trustworthy, and second-level candidates, which
are possible microlensing but have lower signal-to-noise and are more
questionable. The pipeline leaves just 3 first-level candidates, all of which
have very short full-width half-maximum timescale (<5 days) and 3 second-level
candidates, which have timescales of 31, 36 and 51 days respectively. We also
show 16 third-level lightcurves, as an illustration of the events that just
fail the threshold for designation as microlensing candidates. They are almost
certainly mainly variable stars. Two of the 3 first-level candidates correspond
to known events (PA 00-S3 and PA 00-S4) already reported by the POINT-AGAPE
project. The remaining first-level candidate is new.Comment: 22 pages, 18 figures, MNRAS, to appea
Mass spectrometric gas composition measurements associated with jet interaction tests in a high-enthalpy wind tunnel
Knowledge of test gas composition is important in wind-tunnel experiments measuring aerothermodynamic interactions. This paper describes measurements made by sampling the top of the test section during runs of the Langley 7-Inch High-Temperature Tunnel. The tests were conducted to determine the mixing of gas injected from a flat-plate model into a combustion-heated hypervelocity test stream and to monitor the CO2 produced in the combustion. The Mass Spectrometric (MS) measurements yield the mole fraction of N2 or He and CO2 reaching the sample inlets. The data obtained for several tunnel run conditions are related to the pressures measured in the tunnel test section and at the MS ionizer inlet. The apparent distributions of injected gas species and tunnel gas (CO2) are discussed relative to the sampling techniques. The measurements provided significant real-time data for the distribution of injected gases in the test section. The jet N2 diffused readily from the test stream, but the jet He was mostly entrained. The amounts of CO2 and Ar diffusing upward in the test section for several run conditions indicated the variability of the combustion-gas test-stream composition
The POINT-AGAPE Survey: Comparing Automated Searches of Microlensing Events toward M31
Searching for microlensing in M31 using automated superpixel surveys raises a
number of difficulties which are not present in more conventional techniques.
Here we focus on the problem that the list of microlensing candidates is
sensitive to the selection criteria or "cuts" imposed and some subjectivity is
involved in this. Weakening the cuts will generate a longer list of
microlensing candidates but with a greater fraction of spurious ones;
strengthening the cuts will produce a shorter list but may exclude some genuine
events. We illustrate this by comparing three analyses of the same data-set
obtained from a 3-year observing run on the INT in La Palma. The results of two
of these analyses have been already reported: Belokurov et al. (2005) obtained
between 3 and 22 candidates, depending on the strength of their cuts, while
Calchi Novati et al. (2005) obtained 6 candidates. The third analysis is
presented here for the first time and reports 10 microlensing candidates, 7 of
which are new. Only two of the candidates are common to all three analyses. In
order to understand why these analyses produce different candidate lists, a
comparison is made of the cuts used by the three groups...Comment: 28 pages, 24 figures, 9 table
Algebraic totality, towards completeness
Finiteness spaces constitute a categorical model of Linear Logic (LL) whose
objects can be seen as linearly topologised spaces, (a class of topological
vector spaces introduced by Lefschetz in 1942) and morphisms as continuous
linear maps. First, we recall definitions of finiteness spaces and describe
their basic properties deduced from the general theory of linearly topologised
spaces. Then we give an interpretation of LL based on linear algebra. Second,
thanks to separation properties, we can introduce an algebraic notion of
totality candidate in the framework of linearly topologised spaces: a totality
candidate is a closed affine subspace which does not contain 0. We show that
finiteness spaces with totality candidates constitute a model of classical LL.
Finally, we give a barycentric simply typed lambda-calculus, with booleans
and a conditional operator, which can be interpreted in this
model. We prove completeness at type for
every n by an algebraic method
Hermetic storage - an ecofriendly safe storage method for long term storage of black gram: Poster
India is the primary origin of the black gram that is majorly cultivated in the southern part of Asian countries. About 70% of world black gram production comes from India. Black gram is more prone to insect infestation and microorganisms resulting in deterioration of grain quality. These losses can be controlled by following appropriate storage method at farmerâs level. Eco-friendly, safe storage methods are demanded by the customers due to food safety, quality and environmental issues. Hermetic storage is a safe storage method, suitable for long term storage without usage of chemical pesticides. It creates an air tight environment to rapidly exterminate insect development and suppresses micro floral activity. A study was conducted to identify the suitable, cost effective storage method for safe storage of black gram at the farm level. Hermetic bags were made by using different combinations of gunny, polypropylene & storezo bags for the safe storage of black gram. The properties of packaging materials viz., thickness, and water vapour transmission rate significantly affected the quality parameters of the black gram stored in various bags. Moisture content, thousand grain mass, bulk density, insect emergence, and germination percentage of black gram stored in various bags were studied over a storage period of 12 months. Black gram stored in polypropylene and gunny bags was infested with pulse beetle by the third month of the storage period. But black gram stored in bags with hermetic bag as inner layer was not infested up to 12 months and could retain the grain quality.India is the primary origin of the black gram that is majorly cultivated in the southern part of Asian countries. About 70% of world black gram production comes from India. Black gram is more prone to insect infestation and microorganisms resulting in deterioration of grain quality. These losses can be controlled by following appropriate storage method at farmerâs level. Eco-friendly, safe storage methods are demanded by the customers due to food safety, quality and environmental issues. Hermetic storage is a safe storage method, suitable for long term storage without usage of chemical pesticides. It creates an air tight environment to rapidly exterminate insect development and suppresses micro floral activity. A study was conducted to identify the suitable, cost effective storage method for safe storage of black gram at the farm level. Hermetic bags were made by using different combinations of gunny, polypropylene & storezo bags for the safe storage of black gram. The properties of packaging materials viz., thickness, and water vapour transmission rate significantly affected the quality parameters of the black gram stored in various bags. Moisture content, thousand grain mass, bulk density, insect emergence, and germination percentage of black gram stored in various bags were studied over a storage period of 12 months. Black gram stored in polypropylene and gunny bags was infested with pulse beetle by the third month of the storage period. But black gram stored in bags with hermetic bag as inner layer was not infested up to 12 months and could retain the grain quality
Cross-Over between universality classes in a magnetically disordered metallic wire
In this article we present numerical results of conduction in a disordered
quasi-1D wire in the possible presence of magnetic impurities. Our analysis
leads us to the study of universal properties in different conduction regimes
such as the localized and metallic ones. In particular, we analyse the
cross-over between universality classes occurring when the strength of magnetic
disorder is increased. For this purpose, we use a numerical Landauer approach,
and derive the scattering matrix of the wire from electron's Green's function.Comment: Final version, accepted for publication in New Journ. of Physics, 27
pages, 28 figures. Replaces the earlier shorter preprint arXiv:0910.427
Completed cohomology of Shimura curves and a p-adic Jacquet-Langlands correspondence
We study indefinite quaternion algebras over totally real fields F, and give
an example of a cohomological construction of p-adic Jacquet-Langlands
functoriality using completed cohomology. We also study the (tame) levels of
p-adic automorphic forms on these quaternion algebras and give an analogue of
Mazur's `level lowering' principle.Comment: Updated version. Contains some minor corrections compared to the
published versio
The play's the thing
For very understandable reasons phenomenological approaches predominate in the field of sensory urbanism. This paper does not seek to add to that particular discourse. Rather it takes Rortyâs postmodernized Pragmatism as its starting point and develops a position on the role of multi-modal design representation in the design process as a means of admitting many voices and managing multidisciplinary collaboration.
This paper will interrogate some of the concepts underpinning the Sensory Urbanism project to help define the scope of interest in multi-modal representations. It will then explore a range of techniques and approaches developed by artists and designers during the past fifty years or so and comment on how they might inform the question of multi-modal representation. In conclusion I will argue that we should develop a heterogeneous tool kit that adopts, adapts and re-invents existing methods because this will better serve our purposes during the exploratory phase(s) of any design project that deals with complexity
The Anomaly in the Candidate Microlensing Event PA-99-N2
The lightcurve of PA-99-N2, one of the recently announced microlensing
candidates towards M31, shows small deviations from the standard Paczynski
form. We explore a number of possible explanations, including correlations with
the seeing, the parallax effect and a binary lens. We find that the
observations are consistent with an unresolved RGB or AGB star in M31 being
microlensed by a binary lens. We find that the best fit binary lens mass ratio
is about one hundredth, which is one of most extreme values found for a binary
lens so far. If both the source and lens lie in the M31 disk, then the standard
M31 model predicts the probable mass range of the system to be 0.02-3.6 solar
masses (95 % confidence limit). In this scenario, the mass of the secondary
component is therefore likely to be below the hydrogen-burning limit. On the
other hand, if a compact halo object in M31 is lensing a disk or spheroid
source, then the total lens mass is likely to lie between 0.09-32 solar masses,
which is consistent with the primary being a stellar remnant and the secondary
a low mass star or brown dwarf. The optical depth (or alternatively the
differential rate) along the line of sight toward the event indicates that a
halo lens is more likely than a stellar lens provided that dark compact objects
comprise no less than 15 per cent (or 5 per cent) of haloes.Comment: Latex, 23 pages, 9 figures, in press at The Astrophysical Journa
Simulation model for the study of overhead rail current collector systems dynamics, focused on the design of a new conductor rail
Overhead rigid conductor arrangements for current collection for railway traction have some advantages compared to other, more conventional, energy supply systems. They are simple, robust and easily maintained, not to mention their flexibility as to the required height for installation, which makes them particularly suitable for use in subway infrastructures. Nevertheless, due to the increasing speeds of new vehicles running on modern subway lines, a more efficient design is required for this kind of system.
In this paper, the authors present a dynamic analysis of overhead conductor rail systems focused on the design of a new conductor profile with a dynamic behaviour superior to that of the system currently in use. This means that either an increase in running speed can be attained, which at present does not exceed 110 km/h, or an increase in the distance between the rigid catenary supports with the ensuing saving in installation costs.
This study has been carried out using simulation techniques. The ANSYS programme has been used for the finite element modelling and the SIMPACK programme for the elastic multibody systems analysis
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