3,150 research outputs found
Probable solar flare doses encountered on an interplanetary mission as calculated by the MCFLARE code
The computer program, MCFLARE, uses Monte Carlo methods to simulate solar flare occurrences during an interplanetary space voyage. The total biological dose inside a shielded crew compartment due to the flares encountered during the voyage is determined. The computer program evaluates the doses obtained on a large number of trips having identical trajectories. From these results, a dose D sub p having a probability p of not being exceeded during the voyage can be determined as a function of p for any shield material configuration. To illustrate the use of the code, a trip to Mars and return is calculated, and estimated doses behind several thicknesses of aluminum shield and water shield are presented
The norm-1-property of a quantum observable
A normalized positive operator measure has the
norm-1-property if \no{E(X)}=1 whenever . This property reflects
the fact that the measurement outcome probabilities for the values of such
observables can be made arbitrary close to one with suitable state
preparations. Some general implications of the norm-1-property are
investigated. As case studies, localization observables, phase observables, and
phase space observables are considered.Comment: 14 page
EPR Paradox,Locality and Completeness of Quantum Theory
The quantum theory (QT) and new stochastic approaches have no deterministic
prediction for a single measurement or for a single time -series of events
observed for a trapped ion, electron or any other individual physical system.
The predictions of QT being of probabilistic character apply to the statistical
distribution of the results obtained in various experiments. The probability
distribution is not an attribute of a dice but it is a characteristic of a
whole random experiment : '' rolling a dice''. and statistical long range
correlations between two random variables X and Y are not a proof of any causal
relation between these variable. Moreover any probabilistic model used to
describe a random experiment is consistent only with a specific protocol
telling how the random experiment has to be performed.In this sense the quantum
theory is a statistical and contextual theory of phenomena. In this paper we
discuss these important topics in some detail. Besides we discuss in historical
perspective various prerequisites used in the proofs of Bell and CHSH
inequalities concluding that the violation of these inequalities in spin
polarization correlation experiments is neither a proof of the completeness of
QT nor of its nonlocality. The question whether QT is predictably complete is
still open and it should be answered by a careful and unconventional analysis
of the experimental data. It is sufficient to analyze more in detail the
existing experimental data by using various non-parametric purity tests and
other specific statistical tools invented to study the fine structure of the
time-series. The correct understanding of statistical and contextual character
of QT has far reaching consequences for the quantum information and quantum
computing.Comment: 16 pages, 59 references,the contribution to the conference QTRF-4
held in Vaxjo, Sweden, 11-16 june 2007. To be published in the Proceeding
Content bias in the cultural evolution of house finch song
We used three years of house finch, Haemorhous mexicanus, song recordings spanning four decades in the introduced eastern range to assess how individual level cultural transmission mechanisms drive population level changes in birdsong. First, we developed an agent-based model (available as a new R package called ‘TransmissionBias’) that simulates the cultural transmission of house finch song given different parameters related to transmission biases, or biases in social learning that modify the probability of adoption of particular cultural variants. Next, we used approximate Bayesian computation and machine learning to estimate what parameter values likely generated the temporal changes in diversity in our observed data. We found evidence that strong content bias, likely targeted towards syllable complexity, plays a central role in the cultural evolution of house finch song in the New York metropolitan area. Frequency and demonstrator biases appear to be neutral or absent. Additionally, we estimated that house finch song is transmitted with extremely high fidelity. Future studies can use our simulation framework to better understand how cultural transmission and population declines influence song diversity in wild populations.Methods - Recording - Song Analysis and Clustering - Simulation and Generative Inference - Logistic Regression Results Discussio
Strongly Incompatible Quantum Devices
The fact that there are quantum observables without a simultaneous
measurement is one of the fundamental characteristics of quantum mechanics. In
this work we expand the concept of joint measurability to all kinds of possible
measurement devices, and we call this relation compatibility. Two devices are
incompatible if they cannot be implemented as parts of a single measurement
setup. We introduce also a more stringent notion of incompatibility, strong
incompatibility. Both incompatibility and strong incompatibility are rigorously
characterized and their difference is demonstrated by examples.Comment: 27 pages (AMSart), 6 figure
From Copenhagen to neo-Copenhagen interpretation
Positive and negative features of the Copenhagen interpretation are
discussed. As positive features can be mentioned its pragmatism and its
awareness of the crucial role of measurement. However, the main part of the
contribution is devoted to the negative features, to wit, its pragmatism (once
again), its confounding of preparation and measurement, its classical account
of measurement, its completeness claims, the ambiguity of its notion of
correspondence, its confused notion of complementarity. It is demonstrated how
confusions and paradoxes stemming from the negative features of the Copenhagen
interpretation can be dealt with in an amended interpretation, to be referred
to as `neo-Copenhagen interpretation', in which the role of the measuring
instrument is taken seriously by recognizing the quantum mechanical character
of its interaction with the microscopic object. The ensuing necessity of
extending the notion of a quantum mechanical observable from the Hermitian
operator of the standard formalism to the positive operator-valued measure of a
generalized formalism is demonstrated to yield a sound mathematical basis for a
transition from the Copenhagen contextualistic-realist interpretation to the
neo-Copenhagen empiricist one. Applications to the uncertainty relations and to
the Bell inequalities are briefly discussed.Comment: To be published in the Proceedings of the Conference: Quantum Theory
- 4, Reconsideration of Foundations, V\"axj\"o, June 11-16, 200
Classical mechanics as nonlinear quantum mechanics
All measurable predictions of classical mechanics can be reproduced from a
quantum-like interpretation of a nonlinear Schrodinger equation. The key
observation leading to classical physics is the fact that a wave function that
satisfies a linear equation is real and positive, rather than complex. This has
profound implications on the role of the Bohmian classical-like interpretation
of linear quantum mechanics, as well as on the possibilities to find a
consistent interpretation of arbitrary nonlinear generalizations of quantum
mechanics.Comment: 7 pages, invited talk given at conference Quantum Theory:
Reconsideration of Foundations 4, Vaxjo, Sweden, June 11-16, 200
A Curious Geometrical Fact About Entanglement
I sketch how the set of pure quantum states forms a phase space, and then
point out a curiousity concerning maximally entangled pure states: they form a
minimal Lagrangian submanifold of the set of all pure states. I suggest that
this curiousity should have an interesting physical interpretation.Comment: Talk at the Vaxjo conference on Quantum Theory: Reconsideration of
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