9,682 research outputs found

    Bargmann representations for deformed harmonic oscillators

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    Generalizing the case of the usual harmonic oscillator, we look for Bargmann representations corresponding to deformed harmonic oscillators. Deformed harmonic oscillator algebras are generated by four operators a,a†,Na, a^\dagger, N and the unity 1 such as [a,N]=a,[a†,N]=−a†[a,N] = a, [a^\dagger,N] = -a^\dagger, a†a=ψ(N)a^\dagger a = \psi(N) and aa†=ψ(N+1)aa^\dagger =\psi(N+1). We discuss the conditions of existence of a scalar product expressed with a true integral on the space spanned by the eigenstates of aa (or a†a^\dagger). We give various examples, in particular we consider functions ψ\psi that are linear combinations of qNq^N, q−Nq^{-N} and unity and that correspond to q-oscillators with Fock-representations or with non-Fock-representations.Comment: 23 pages, Late

    Contraversive neglect? A modulation of visuospatial neglect in association with contraversive pushing

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    Objective: Contraversive pushing (CP) is a neurologic disorder characterized by a lateral postural imbalance. Pusher patients actively push toward their contralesional side due to a misperception of the body's orientation in relation to gravity. Although not every patient with CP suffers from spatial neglect (SN), both phenomena are highly correlated in right-hemispheric patients. The present study investigates whether peripersonal visuospatial functioning differs in neglect patients with versus without CP (NP+ vs. NP+ patients). Method: Eighteen right-hemispheric stroke patients with SN were included, of which 17 in a double-blind case-control study and 1 single case with posterior pushing to supplement the discourse. A computer-based visuospatial navigation task, in which lateralized deviation can freely emerge, was used to quantify visuospatial behavior. In addition, visuospatial orienting was monitored using line bisection. Results: Significant intergroup differences were found. The NP+ patients demonstrated a smaller ipsilesional navigational deviation and more cross-over (contralesional instead of ipsilesional deviation) in long line bisection. As such, they demonstrated a contraversive (contralesionally directed) shift in comparison with the NP+ patients. Conclusions: These findings highlight the similarity between 2 systems of space representation. They are consistent with a coherence between the neural processing system that mainly provides for postural control, and the one responsible for nonpredominantly postural, visuospatial behavior

    Heavy Quark Lifetimes, Mixing and CP Violation

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    This paper emphasizes four topics that represent some of the year's highlights in heavy quark physics. First of all, a review is given of charm lifetime measurements and how they lead to better understanding of the mechanisms of charm decay. Secondly, the CLEO collaboration's new search for charm mixing is reported, which significantly extends the search for new physics in that sector. Thirdly, important updates in Bs mixing are summarized, which result in a new limit on the mass difference, and which further constrain the unitarity triangle. Finally, the first efforts to measure CP violation in the B system are discussed. Results are shown for the CDF and ALEPH measurements of sin(2beta), as well as the CLEO branching fraction measurements of B-->Kpi,pipi, which have implications for future measurements of alpha.Comment: 25 pages, 15 figures. Talk given at the XIX International Symposium on Lepton and Photon Interactions, Stanford University, August 9-14, 199

    Weighing the Need to Establish Regulatory Takings Doctrine to Justify Takings Standards of Review and Principles

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    This article revisits and examines whether the fairness and justice doctrine of Armstrong v. United States can justify and fashion standards of review to protect the right to just compensation of the Takings Clause. The Court has relied on Armstrong to show the purpose of the Takings Clause in many takings decisions. However, can Armstrong serve a greater purpose? In Dolan v. City of Tigard, the United States Supreme Court applied the unconstitutional conditions doctrine to justify the need for a standard of review to protect the right to just compensation. The Court transported questionable constitutional doctrine to validate Justice Holmes’s regulatory takings theory. Yet, in Tahoe-Sierra Preservation Council v. Tahoe Regional Planning Agency, the Court applied Armstrong’s fairness and justice doctrine to justify not applying standards of review to a complete range of factual theories of regulatory takings theory. Therefore, the Court leads one to ask whether the Armstrong fairness and justice doctrine should be considered in justifying the selection of standards of review and principles to protect the right to just compensation

    Pacific Hake, Merluccius productus, Autecology: A Timely Review

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    Pacific hake, Merluccius productus, the most abundant groundfish in the California Current Large Marine Ecosystem (CCLME), is a species of both commercial significance, supporting a large international fishery, and ecological importance, connecting other species as both predator and prey. Coastal Pacific hake migrations are characterized by movements between northern summer feeding areas and southern winter spawning areas, with variations in annual abundance, distribution, and the extent of these movements associated with varying climate-ocean conditions. In general, warm (cool) years with enhanced (reduced) stratification and poleward (equatorward) transport are often related to good (poor) recruitment, increased (decreased) northward distribution, and reduced (enhanced) growth. However, the classic periodic pattern of annual migration and distribution may no longer be fully representative. Based on recent advances in the understanding of climate-ocean variability off the U.S. west coast, we hypothesize that the annual movements of Pacific hake are more responsive to climate-ocean variability than previously thought, and further, that changes observed in Pacific hake distributions may reflect long-term changes in climate-ocean conditions in the CCLME. Therefore, an updated model of these relations is key to effective monitoring and management of this stock, as well as to devising scenarios of future change in the CCLME as a result of climate variations. The current state of knowledge of the relationship between the Pacific hake and its environment is reviewed, highlighting emerging ideas compared to those of the past, and priorities for future research are suggested
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