1,682 research outputs found
Increasing the Reliability of Adaptive Quadrature Using Explicit Interpolants
We present two new adaptive quadrature routines. Both routines differ from
previously published algorithms in many aspects, most significantly in how they
represent the integrand, how they treat non-numerical values of the integrand,
how they deal with improper divergent integrals and how they estimate the
integration error. The main focus of these improvements is to increase the
reliability of the algorithms without significantly impacting their efficiency.
Both algorithms are implemented in Matlab and tested using both the "families"
suggested by Lyness and Kaganove and the battery test used by Gander and
Gautschi and Kahaner. They are shown to be more reliable, albeit in some cases
less efficient, than other commonly-used adaptive integrators.Comment: 32 pages, submitted to ACM Transactions on Mathematical Softwar
First microlensing candidate towards M31 from the Nainital Microlensing Survey
We report our first microlensing candidate NMS-E1 towards M31 from the data
accumulated during the four years of Nainital Microlensing Survey. Cousin R and
I band observations of ~13'x13' field in the direction of M31 have been carried
out since 1998 and data is analysed using the pixel technique proposed by the
AGAPE collaboration. NMS-E1 lies in the disk of M31 at \alpha = 0:43:33.3 and
\delta = +41:06:44, about 15.5 arcmin to the South-East direction of the center
of M31. The degenerate Paczy\'{n}ski fit gives a half intensity duration of ~59
days. The photometric analysis of the candidate shows that it reached R~20.1
mag at the time of maximum brightness and the colour of the source star was
estimated to be (R-I)_0 ~ 1.1 mag. The microlensing candidate is blended by red
variable stars; consequently the light curves do not strictly follow the
characteristic Paczy\'{n}ski shape and achromatic nature. However its long
period monitoring and similar behaviour in R and I bands supports its
microlensing nature.Comment: no changes except typos corrected, to appear in A&
What are communities of practice? A comparative review of four seminal works
This paper is a comparative review of four seminal works on communities of practice. It is argued that the ambiguities of the terms community and practice are a source of the concept's reusability allowing it to be reappropriated for different purposes, academic and practical. However, it is potentially confusing that the works differ so markedly in their conceptualizations of community, learning, power and change, diversity and informality. The three earlier works are underpinned by a common epistemological view, but Lave and Wenger's 1991 short monograph is often read as primarily about the socialization of newcomers into knowledge by a form of apprenticeship, while the focus in Brown and Duguid's article of the same year is, in contrast, on improvising new knowledge in an interstitial group that forms in resistance to management. Wenger's 1998 book treats communities of practice as the informal relations and understandings that develop in mutual engagement on an appropriated joint enterprise, but his focus is the impact on individual identity. The applicability of the concept to the heavily individualized and tightly managed work of the twenty-first century is questionable. The most recent work by Wenger – this time with McDermott and Snyder as coauthors – marks a distinct shift towards a managerialist stance. The proposition that managers should foster informal horizontal groups across organizational boundaries is in fact a fundamental redefinition of the concept. However it does identify a plausible, if limited, knowledge management (KM) tool. This paper discusses different interpretations of the idea of 'co-ordinating' communities of practice as a management ideology of empowerment
Nuclear Data for Sustainable Nuclear Energy
Final report of a coordinated action on nuclear data for industrial development in Europe (CANDIDE).
The successful development of advanced nuclear systems for sustainable energy production depends on high-level modelling capabilities for the reliable and cost-effective design and safety assessment of such systems, and for the interpretation of key benchmark experiments needed for performance and safety evaluations. High-quality nuclear data, in particular complete and accurate information about the nuclear reactions taking place in advanced reactors and the fuel cycle, are an essential component of such modelling capabilities.
In the CANDIDE project, nuclear data needs for sustainable nuclear energy production and waste management have been analyzed and categorized, on the basis of preliminary design studies of innovative systems. Meeting those needs will require that the quality of nuclear data files be considerably improved. The CANDIDE project has produced a set of recommendations, or roadmap, for sustainable nuclear data development. In conclusion, a substantial long-term investment in an integrated European nuclear data development program is called for, complemented by some dedicated actions targeting specific issues.JRC.D.5-Neutron physic
Tau Be or not Tau Be? - A Perspective on Service Compatibility and Substitutability
One of the main open research issues in Service Oriented Computing is to
propose automated techniques to analyse service interfaces. A first problem,
called compatibility, aims at determining whether a set of services (two in
this paper) can be composed together and interact with each other as expected.
Another related problem is to check the substitutability of one service with
another. These problems are especially difficult when behavioural descriptions
(i.e., message calls and their ordering) are taken into account in service
interfaces. Interfaces should capture as faithfully as possible the service
behaviour to make their automated analysis possible while not exhibiting
implementation details. In this position paper, we choose Labelled Transition
Systems to specify the behavioural part of service interfaces. In particular,
we show that internal behaviours (tau transitions) are necessary in these
transition systems in order to detect subtle errors that may occur when
composing a set of services together. We also show that tau transitions should
be handled differently in the compatibility and substitutability problem: the
former problem requires to check if the compatibility is preserved every time a
tau transition is traversed in one interface, whereas the latter requires a
precise analysis of tau branchings in order to make the substitution preserve
the properties (e.g., a compatibility notion) which were ensured before
replacement.Comment: In Proceedings WCSI 2010, arXiv:1010.233
Search for exoplanets in M31 with pixel-lensing and the PA-99-N2 event revisited
Several exoplanets have been detected towards the Galactic bulge with the
microlensing technique. We show that exoplanets in M31 may also be detected
with the pixel-lensing method, if telescopes making high cadence observations
of an ongoing microlensing event are used. Using a Monte Carlo approach we find
that the mean mass for detectable planetary systems is about .
However, even small mass exoplanets () can cause
significant deviations, which are observable with large telescopes. We
reanalysed the POINT-AGAPE microlensing event PA-99-N2. First, we test the
robustness of the binary lens conclusion for this light curve. Second, we show
that for such long duration and bright microlensing events, the efficiency for
finding planetary-like deviations is strongly enhanced with respect to that
evaluated for all planetary detectable events.Comment: 14 pages, 8 figures. Paper presented at the "II Italian-Pakistani
Workshop on Relativistic Astrophysics, Pescara, July 8-10, 2009. To be
published in a special issue of General Relativity and Gravitation (eds. F.
De Paolis, G.F.R. Ellis, A. Qadir and R. Ruffini
First Measurement of Gamma(D*+) and Precision Measurement of m_D*+ - m_D0
We present the first measurement of the D*+ width using 9/fb of e+ e- data
collected near the Upsilon(4S) resonance by the CLEO II.V detector. Our method
uses advanced tracking techniques and a reconstruction method that takes
advantage of the small vertical size of the CESR beam spot to measure the
energy release distribution from the D*+ -> D0 pi+ decay. We find Gamma(D*+) =
96 +- 4 (Statistical) +- 22 (Systematic) keV. We also measure the energy
release in the decay and compute Delta m = m(D*+) - m(D0) = 145.412 +- 0.002
(Statistical) +- 0.012 (Systematic) MeV/c^2Comment: 24 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to PR
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
Evaluation of the fineness of degummed bast fibers
Fiber fineness characteristics are important for yarn production and quality. In this paper, degummed bast fibers such as hemp, flax and ramie have been examined with the Optical Fiber Diameter Analyzer (OFDA100 and OFDA2000) systems for fiber fineness, in comparison with the conventional image analysis and the Wira airflow tester. The correlation between the results from these measurements was analysed. The results indicate that there is a significant linear co-relation between the fiber fineness measurement results obtained from those different systems. In addition, the mean fiber width and its coefficient of variation obtained from the OFDA100 system are smaller than those obtained from the OFDA2000 system, due to the difference in sample preparation methods. The OFDA2000 system can also measure the fiber fineness profile along the bast fiber plants, which can be useful for plant breeding. <br /
A pilot study comparing the metabolic profiles of elite-level athletes from different sporting disciplines
Background: The outstanding performance of an elite athlete might be associated with changes in their blood metabolic profile. The aims of this study were to compare the blood metabolic profiles between moderate- and high-power and endurance elite athletes and to identify the potential metabolic pathways underlying these differences. Methods: Metabolic profiling of serum samples from 191 elite athletes from different sports disciplines (121 high- and 70 moderate-endurance athletes, including 44 high- and 144 moderate-power athletes), who participated in national or international sports events and tested negative for doping abuse at anti-doping laboratories, was performed using non-targeted metabolomics-based mass spectroscopy combined with ultrahigh-performance liquid chromatography. Multivariate analysis was conducted using orthogonal partial least squares discriminant analysis. Differences in metabolic levels between high- and moderate-power and endurance sports were assessed by univariate linear models. Results: Out of 743 analyzed metabolites, gamma-glutamyl amino acids were significantly reduced in both high-power and high-endurance athletes compared to moderate counterparts, indicating active glutathione cycle. High-endurance athletes exhibited significant increases in the levels of several sex hormone steroids involved in testosterone and progesterone synthesis, but decreases in diacylglycerols and ecosanoids. High-power athletes had increased levels of phospholipids and xanthine metabolites compared to moderate-power counterparts. Conclusions: This pilot data provides evidence that high-power and high-endurance athletes exhibit a distinct metabolic profile that reflects steroid biosynthesis, fatty acid metabolism, oxidative stress, and energy-related metabolites. Replication studies are warranted to confirm differences in the metabolic profiles associated with athletes’ elite performance in independent data sets, aiming ultimately for deeper understanding of the underlying biochemical processes that could be utilized as biomarkers with potential therapeutic implications
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