3,957 research outputs found
Measured limits to contamination of optical surfaces by elastomers in vacuum
We have monitored the reflectivity of mirrors that were exposed to a fluoroelastomer (3M-Fluorel 2176) and a room-temperature vulcanizing silicone rubber (RTV-615) in vacuum. The 95% confidence limit on the decrease of mirror reflectivities was less than 0.35 ppm/week for Fluorel and <0.29 ppm@week for RTV-615
The first direct detection of gravitational waves opens a vast new frontier in astronomy
The first direct detection of gravitational waves (GWs),
announced on 11 February 2016, has opened a vast new
frontier in astronomy. Albert Einstein predicted the existence of these waves about a century ago as a consequence of his general theory of relativity. Radio
astronomy observations of the binary pulsar system PSR
1913 + 16 over a 20 year period beginning in 1975 provided
strong observational evidence that gravitational waves carried energy away from the orbits of neutron stars at precisely the level predicted by general relativity
(GR). This relentless conversion of orbital energy into
gravitational wave energy causes binary orbits to decay
until the objects eventually collide and merge. The frontier
of precision measurement science, using laser interferometers, was pushed for more than four decades to
achieve this first direct detection, marking a milestone in
experimental physics and engineering. Even more significantly, this milestone also opens a new window onto our universe and a completely new kind of astronomy to
explore
Industrija čelika u novim članicama EU u usporedbi s globalnim trendovima
Accession of the metallurgically significant countries of the Central and Eastern Europe to the EU in 2004 was conditioned by fulfilling the Restructuring Programs as the foundation for achievement of competitiveness and guarancy of viability. The Restructuring Programs, which fulfilling and regular monitoring had lasted 5 years, demonstrated the right of the significant position of the steel industry in the new EU members, especially in Poland, Czech Republic, Slovakia, and in Hungary. The objective of the article is to point to the key elements in context of steel industry global trends, regarding either production or especially utility values and total consumption. In this connection, privatization took an important role too.Prinos metalurgije glavnih zemalja Srednje i Istočne Europe u EU u 2004. je bilo ostvarenje restrukturiranja programa kao temelj za postizanje konkurentnosti i jamstvo opstanka. Restrukturiranje programa, provedba i redovito praćenj za 5 godina opravdalo je značajno mjesto u industriji čelika u novim zemljama EU, naročito u Poljskoj, Češkoj, Slovačkoj i Mađarskoj. Ovaj članak ima za cilj istaknuti ključne elemente u razvojnom konextu industrija čelika u svijetu, kako u pogledu proizvodnje, a posebice u odnosu na kvalitete i ukupnu potrošnju. Važan element u tom pogledu, nastavak privatizacije
Electromagnetic multipole theory for optical nanomaterials
Optical properties of natural or designed materials are determined by the
electromagnetic multipole moments that light can excite in the constituent
particles. In this work we present an approach to calculate the multipole
excitations in arbitrary arrays of nanoscatterers in a dielectric host medium.
We introduce a simple and illustrative multipole decomposition of the electric
currents excited in the scatterers and link this decomposition to the classical
multipole expansion of the scattered field. In particular, we find that
completely different multipoles can produce identical scattered fields. The
presented multipole theory can be used as a basis for the design and
characterization of optical nanomaterials
The Random Bit Complexity of Mobile Robots Scattering
We consider the problem of scattering robots in a two dimensional
continuous space. As this problem is impossible to solve in a deterministic
manner, all solutions must be probabilistic. We investigate the amount of
randomness (that is, the number of random bits used by the robots) that is
required to achieve scattering. We first prove that random bits are
necessary to scatter robots in any setting. Also, we give a sufficient
condition for a scattering algorithm to be random bit optimal. As it turns out
that previous solutions for scattering satisfy our condition, they are hence
proved random bit optimal for the scattering problem. Then, we investigate the
time complexity of scattering when strong multiplicity detection is not
available. We prove that such algorithms cannot converge in constant time in
the general case and in rounds for random bits optimal
scattering algorithms. However, we present a family of scattering algorithms
that converge as fast as needed without using multiplicity detection. Also, we
put forward a specific protocol of this family that is random bit optimal ( random bits are used) and time optimal ( rounds are used).
This improves the time complexity of previous results in the same setting by a
factor. Aside from characterizing the random bit complexity of mobile
robot scattering, our study also closes its time complexity gap with and
without strong multiplicity detection (that is, time complexity is only
achievable when strong multiplicity detection is available, and it is possible
to approach it as needed otherwise)
Motional sidebands and direct measurement of the cooling rate in the resonance fluorescence of a single trapped ion
Resonance fluorescence of a single trapped ion is spectrally analyzed using a
heterodyne technique. Motional sidebands due to the oscillation of the ion in
the harmonic trap potential are observed in the fluorescence spectrum. From the
width of the sidebands the cooling rate is obtained and found to be in
agreement with the theoretical prediction.Comment: 4 pages, 4 figures. Final version after minor changes, 1 figure
replaced; to be published in PRL, July 10, 200
When are summary ROC curves appropriate for diagnostic meta-analyses?
Diagnostic tests are increasingly evaluated with systematic reviews and this has lead to the recent developments of statistical methods to analyse such data. The most commonly used method is the summary receiver operating characteristic (SROC) curve, which can be fitted with a non-linear bivariate random-effects model. This paper focuses on the practical problems of interpreting and presenting data from such analyses. First, many meta-analyses may be underpowered to obtain reliable estimates of the SROC parameters. Second, the SROC model may be inappropriate. In these situations, a summary with two univariate meta-analyses of the true and false positive rates (TPRs and FPRs) may be more appropriate. We characterize the type of problems that can occur in fitting these models and present an algorithm to guide the analyst of such studies, with illustrations from analyses of published data. A set of R functions, freely available to perform these analyses, can be downloaded from (www.diagmeta.info)
3-loop heavy flavor Wilson coefficients in deep-inelastic scattering
We present our most recent results on the calculation of the heavy flavor
contributions to deep-inelastic scattering at 3-loop order in the large
limit, where the heavy flavor Wilson coefficients are known to factorize into
light flavor Wilson coefficients and massive operator matrix elements. We
describe the different techniques employed for the calculation and show the
results in the case of the heavy flavor non-singlet and pure singlet
contributions to the structure function .Comment: 4 pages Latex, 2 style files, 4 Figures, Contribution to the
Proceedings of QCD '14, Montpellier, Jult 201
3-Loop Corrections to the Heavy Flavor Wilson Coefficients in Deep-Inelastic Scattering
A survey is given on the status of 3-loop heavy flavor corrections to
deep-inelastic structure functions at large enough virtualities .Comment: 13 pages Latex, 8 Figures, Contribution to the Proceedings of EPS
2015 Wie
Recent progress on the calculation of three-loop heavy flavor Wilson coefficients in deep-inelastic scattering
We report on our latest results in the calculation of the three-loop heavy
flavor contributions to the Wilson coefficients in deep-inelastic scattering in
the asymptotic region . We discuss the different methods used to
compute the required operator matrix elements and the corresponding Feynman
integrals. These methods very recently allowed us to obtain a series of new
operator matrix elements and Wilson coefficients like the flavor non-singlet
and pure singlet Wilson coefficients.Comment: 11 pages Latex, 2 Figures, Proc. of Loops and Legs in Quantum Field
Theory, April 2014, Weimar, German
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