35,739 research outputs found
AB effect and Aharonov-Susskind charge non-superselection
We consider a particle in a coherent superposition of states with different
electric charge moving in the vicinity of a magnetic flux. Formally, it should
acquire a (gauge-dependent) AB relative phase between the charge states, even
for an incomplete loop. If measureable, such a geometric, rather than
topological, AB-phase would seem to break gauge invariance. Wick, Wightman and
Wigner argued that since (global) charge-dependent phase transformations are
physically unobservable, charge state superpositions are unphysical (`charge
superselection rule'). This would resolve the apparent paradox in a trivial
way. However, Aharonov and Susskind disputed this superselection rule: they
distinguished between such global charge-dependent transformations, and
transformations of the relative inter-charge phases of two particles, and
showed that the latter \emph{could} in principle be observable! Finally, the
paradox again disappears once we considers the `calibration' of the phase
measured by the Aharonov-Susskind phase detectors, as well as the phase of the
particle at its initial point. It turns out that such a detector can only
distinguish between the relative phases of two paths if their (oriented)
difference forms a loop around the flux
Correlated Equilibria of Classical Strategic Games with Quantum Signals
Correlated equilibria are sometimes more efficient than the Nash equilibria
of a game without signals. We investigate whether the availability of quantum
signals in the context of a classical strategic game may allow the players to
achieve even better efficiency than in any correlated equilibrium with
classical signals, and find the answer to be positive.Comment: 8 pages, LaTe
Zeno effect and ergodicity in finite-time quantum measurements
We demonstrate that an attempt to measure a non-local in time quantity, such
as the time average \la A\ra_T of a dynamical variable , by separating
Feynman paths into ever narrower exclusive classes traps the system in
eigensubspaces of the corresponding operator \a. Conversely, in a long
measurement of \la A\ra_T to a finite accuracy, the system explores its
Hilbert space and is driven to a universal steady state in which von Neumann
ensemble average of \a coincides with \la A\ra_T. Both effects are
conveniently analysed in terms of singularities and critical points of the
corresponding amplitude distribution and the Zeno-like behaviour is shown to be
a consequence of conservation of probability
Survey for Etomopathogenic Nematodes and Entomopathogenic Fungi in Alfalfa Snout Beetle, \u3ci\u3eOtiorhynchus Ligustici\u3c/i\u3e (L.) (Coleoptera: Curculionidae), Infested Fields in Hungary and in New York State
A survey for etomopathogenic nematodes and fungi in alfalfa snout beetle Otiorhynchus ligustici (L.) infested fields was conducted in Hungary, where this beetle is native, and in New York State, where the alfalfa snout beetle is an invasive species. Soil samples were collected in Hungary and in New York in alfalfa snout beetle infested alfalfa fields in spring 2002. Galleria mellonella (L.) larvae were used as bait insects. The entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae were found in Hungary and New York. The frequency of plots with entomopathogenic fungi was not significantly different between locations in Hungary and New York. The entomopathogenic nematodes Steinernema carpocapsae and Heterorhabditis sp. were found in Hungary and New York and S. feltiae was only found in Hungary. The frequency of plots with entomopathogenic nematodes was not significantly different between locations in Hungary and New York. S. carpocapsae and S. feltiae were found in coexistence at one location in Hungary
Field Persistence of \u3ci\u3eSteinernema Carpocapsa\u3c/i\u3e Weiser (Ny001), \u3ci\u3eSteinernema Feltiae\u3c/i\u3e Filipjev (Valko) and \u3ci\u3eHeterorhabditis Bacteriophora\u3c/i\u3e Poinar (Oswego) in Alfalfa Fields
The long term field persistence of Steinernema carpocapsae Weiser, strain NY001, S. feltiae Filipjev, strain Valko and Heterorhabditis bacteriophora Poinar, strain Oswego was investigated in an alfalfa field infested by the alfalfa snout beetle, Otiorhynchus ligustici L. Nematodes were applied in single-species, two-species and three-species combinations at a total of 2.5 × 109 infective juveniles per hectare. Soil samples were taken approximately every two weeks from mid/late May to late October in 2004 and 2005. Two soil samplings were conducted in 2006 at the end of May and in early July. All nematodes persisted in the field at the time of the last sampling in July 2006, over two years after application suggesting long term persistence of these nematodes and the potential to coexist in combinations. Steinernema feltiae Valko was not detected in the three-species combination after June 8, 2005, approximately one year after nematode application suggesting that S. feltiae Valko cannot compete effectively when a specialized ambusher nematode (S. carpocapsae NY001) and a specialized cruiser nematode (H. bacteriophora Oswego) are present simultaneously. In 2006, two years after nematode application, a marked movement of nematodes into experimental plots where they were not applied was observed. S. carpocapsae NY001 was found in the highest number of plots where it wasn’t applied. Given the ambusher behavior of S. carpocapsae NY001, it is suspected that its movement occurred via infected, but still live adult alfalfa snout beetles
Ergonomics Contributions to Company Strategies
Managers usually associate ergonomics with occupational health and safety and related legislation, not with business performance. In many companies, these decision makers seem not to be positively motivated to apply ergonomics for reasons of improving health and safety. In order to strengthen the position of ergonomics and ergonomists in the business and management world, we discuss company strategies and business goals to which ergonomics could contribute. Conceptual models are presented and examples are given to illustrate: 1) the present situation in which ergonomics is not part of regular planning and control cycles in organizations to ensure business performance, and 2) the desired situation in which ergonomics is an integrated part of strategy formulation and implementation. In order to realize the desired situation, considerable changes must take place within the ergonomics research, education and practice community by moving from a health ergonomics paradigm to a business ergonomics paradigm, without losing the health and safety goals.corporate strategy;paradigm shift;system performance
Unexpected reemergence of von Neumann theorem
Is is shown here that the "simple test of quantumness for a single system" of
arXiv:0704.1962 (for a recent experimental realization see arXiv:0804.1646) has
exactly the same relation to the discussion of to the problem of describing the
quantum system via a classical probabilistic scheme (that is in terms of hidden
variables, or within a realistic theory) as the von Neumann theorem (1932). The
latter one was shown by Bell (1966) to stem from an assumption that the hidden
variable values for a sum of two non-commuting observables (which is an
observable too) have to be, for each individual system, equal to sums of
eigenvalues of the two operators. One cannot find a physical justification for
such an assumption to hold for non-commeasurable variables. On the positive
side. the criterion may be useful in rejecting models which are based on
stochastic classical fields. Nevertheless the example used by the Authors has a
classical optical realization
Pseudo-Hermitian Quantum Mechanics with Unbounded Metric Operators
We extend the formulation of pseudo-Hermitian quantum mechanics to
eta-pseudo-Hermitian Hamiltonian operators H with an unbounded metric operator
eta. In particular, we give the details of the construction of the physical
Hilbert space, observables, and equivalent Hermitian Hamiltonian for the case
that H has a real and discrete spectrum and its eigenvectors belong to the
domain of eta and consequently its positive square root.Comment: 8 pages, accepted for publication in Phil. Trans. R. Soc.
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