341 research outputs found
Toward Quantum Superposition of Living Organisms
The most striking feature of quantum mechanics is the existence of
superposition states, where an object appears to be in different situations at
the same time. The existence of such states has been tested with small objects,
like atoms, ions, electrons and photons, and even with molecules. More
recently, it has been possible to create superpositions of collections of
photons, atoms, or Cooper pairs. Current progress in optomechanical systems may
soon allow us to create superpositions of even larger objects, like micro-sized
mirrors or cantilevers, and thus to test quantum mechanical phenomena at larger
scales. Here we propose a method to cool down and create quantum superpositions
of the motion of sub-wavelength, arbitrarily shaped dielectric objects trapped
inside a high--finesse cavity at a very low pressure. Our method is ideally
suited for the smallest living organisms, such as viruses, which survive under
low vacuum pressures, and optically behave as dielectric objects. This opens up
the possibility of testing the quantum nature of living organisms by creating
quantum superposition states in very much the same spirit as the original
Schr\"odinger's cat "gedanken" paradigm. We anticipate our essay to be a
starting point to experimentally address fundamental questions, such as the
role of life and consciousness in quantum mechanics.Comment: 9 pages, 4 figures, published versio
Machine Learning and Prediction in Psychological Assessment: Some Promises and Pitfalls
Multivariate analysis of psychological dat
Artificial intelligence, machine learning, and other demons
Multivariate analysis of psychological dat
Why we need systematic reviews and meta-analyses in the testing and assessment literature
Multivariate analysis of psychological dat
Search for Bremsstrahlung radiation in quasi-free n p --> n p gamma reactions
Due to the high sensitivity of the N N --> N N gamma reaction to the
nucleon-nucleon potential, Bremsstrahlung radiation is used as a tool to
investigate details of the nucleon-nucleon interaction. Such investigations can
be performed at the cooler synchrotron COSY in the Research Centre Juelich, by
dint of the COSY-11 detection system. The results of the identification of
Bremsstrahlung radiation emitted via the d p --> d p gamma reaction in data
taken with a proton target and a deuteron beam are presented and discussed.Comment: 3 pages; Presented at Meson 2004: 8th International Workshop on Meson
Production, Properties and Interaction, Krakow, Poland, 4-8 June 2004;
Submitted to International Journal of Modern Physics
A Precision Measurement of pp Elastic Scattering Cross Sections at Intermediate Energies
We have measured differential cross sections for \pp elastic scattering with
internal fiber targets in the recirculating beam of the proton synchrotron
COSY. Measurements were made continuously during acceleration for projectile
kinetic energies between 0.23 and 2.59 GeV in the angular range deg. Details of the apparatus and the data analysis are
given and the resulting excitation functions and angular distributions
presented. The precision of each data point is typically better than 4%, and a
relative normalization uncertainty of only 2.5% within an excitation function
has been reached. The impact on phase shift analysis as well as upper bounds on
possible resonant contributions in lower partial waves are discussed.Comment: 23 pages 29 figure
Measurement of Spin Correlation Parameters A, A, and A_ at 2.1 GeV in Proton-Proton Elastic Scattering
At the Cooler Synchrotron COSY/J\"ulich spin correlation parameters in
elastic proton-proton (pp) scattering have been measured with a 2.11 GeV
polarized proton beam and a polarized hydrogen atomic beam target. We report
results for A, A, and A_ for c.m. scattering angles between
30 and 90. Our data on A -- the first measurement of this
observable above 800 MeV -- clearly disagrees with predictions of available of
pp scattering phase shift solutions while A and A_ are reproduced
reasonably well. We show that in the direct reconstruction of the scattering
amplitudes from the body of available pp elastic scattering data at 2.1 GeV the
number of possible solutions is considerably reduced.Comment: 4 pages, 4 figure
Exclusive Measurements of pp -> dpi+pi0: Double-Pionic Fusion without ABC Effect
Exclusive measurements of the reaction pp -> dpi+pi0 have been carried out at
T_p = 1.1 GeV at the CELSIUS storage ring using the WASA detector. The
isovector pi+pi0 channel exhibits no enhancement at low invariant pipi masses,
i. e. no ABC effect. The differential distributions are in agreement with the
conventional t-channel Delta-Delta excitation process, which also accounts for
the observed energy dependence of the total cross section. This is an update of
a previously published version -- see important note at the end of the article
Evaluation of a Bayesian inference network for ligand-based virtual screening
Background
Bayesian inference networks enable the computation of the probability that an event will occur. They have been used previously to rank textual documents in order of decreasing relevance to a user-defined query. Here, we modify the approach to enable a Bayesian inference network to be used for chemical similarity searching, where a database is ranked in order of decreasing probability of bioactivity.
Results
Bayesian inference networks were implemented using two different types of network and four different types of belief function. Experiments with the MDDR and WOMBAT databases show that a Bayesian inference network can be used to provide effective ligand-based screening, especially when the active molecules being sought have a high degree of structural homogeneity; in such cases, the network substantially out-performs a conventional, Tanimoto-based similarity searching system. However, the effectiveness of the network is much less when structurally heterogeneous sets of actives are being sought.
Conclusion
A Bayesian inference network provides an interesting alternative to existing tools for ligand-based virtual screening
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