4,469 research outputs found

    Contrasting Regulation of Catecholamine Neurotransmission in the Behaving Brain: Pharmacological Insights from an Electrochemical Perspective

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    Catecholamine neurotransmission plays a key role in regulating a variety of behavioral and physiologic processes, and its dysregulation is implicated in both neurodegenerative and neuropsychiatric disorders. Over the last four decades, in vivo electrochemistry has enabled the discovery of contrasting catecholamine regulation in the brain. These rapid and spatially resolved measurements have been conducted in brain slices, and in anesthetized and freely behaving animals. In this review, we describe the methods enabling in vivo measurements of dopamine and norepinephrine, and subsequent findings regarding their release and regulation in intact animals. We thereafter discuss key studies in awake animals, demonstrating that these catecholamines are not only differentially regulated, but are released in opposition of each other during appetitive and aversive stimuli

    A fundamental approach to the sticking of insect residues to aircraft wings

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    A proposed testing scheme is described for obtaining data on the effects of surface roughness and surface energy on insect adhesion. The road test apparatus is discussed as well as surface preparation techniques. Uncoated and polymer coated metal substrates were analyzed by SEM/ESCA/IRS before and following collision with insects. Critical surface tensions of unexposed Nyebar and poly sulfone coatings were 10 and 33 dynes/cm, respectively, as determined from contact angles. A total of 95% of insect residues collected belong to order Diptera. Significantly less insect debris was detected on the coated plates as compared to the uncoated plates. Minimal contamination at the 5 nm level of both coated and uncoated plates occurs even after hours of exposure to road conditions as determined by ESCA analysis. The presence of nitrogen detected by ESCA on exposed plates is unequivocal evidence for insect residues left on plates

    On the Localization of One-Photon States

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    Single photon states with arbitrarily fast asymptotic power-law fall-off of energy density and photodetection rate are explicitly constructed. This goes beyond the recently discovered tenth power-law of the Hellwarth-Nouchi photon which itself superseded the long-standing seventh power-law of the Amrein photon.Comment: 7 pages, tex, no figure

    The structure of the quantum mechanical state space and induced superselection rules

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    The role of superselection rules for the derivation of classical probability within quantum mechanics is investigated and examples of superselection rules induced by the environment are discussed.Comment: 11 pages, Standard Latex 2.0

    Relativistic Operator Description of Photon Polarization

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    We present an operator approach to the description of photon polarization, based on Wigner's concept of elementary relativistic systems. The theory of unitary representations of the Poincare group, and of parity, are exploited to construct spinlike operators acting on the polarization states of a photon at each fixed energy momentum. The nontrivial topological features of these representations relevant for massless particles, and the departures from the treatment of massive finite spin representations, are highlighted and addressed.Comment: Revtex 9 page

    Interacting Vector-Spinor and Nilpotent Supersymmetry

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    We formulate an interacting theory of a vector-spinor field that gauges anticommuting spinor charges \{Q_\alpha{}^I, Q_\beta{}^J \} = 0 in arbitrary space-time dimensions. The field content of the system is (\psi_\mu{}^{\alpha I}, \chi^{\alpha I J}, A_\mu{}^I), where \psi_\mu{}^{\alpha I} is a vector-spinor in the adjoint representation of an arbitrary gauge group, and A_\mu{}^I is its gauge field, while \chi^{\alpha I J} is an extra spinor with antisymmetric adjoint indices I J. Amazingly, the consistency of the vector-spinor field equation is maintained, despite its non-trivial interactions.Comment: 10 pages, no figure

    Cross-hemispheric dopamine projections have functional significance

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    Decades of research have described dopamine’s importance in reward-seeking behavior and motor control. Although numerous investigations have focused on dopamine’s mechanisms in modulating behavior, the long-standing belief that dopamine neurons project solely unilaterally has limited the exploration of interhemispheric dopamine signaling. Here we resolve disparate descriptions of unilateral vs. bilateral projections by reporting that dopamine neurons can release dopamine in the contralateral hemisphere. Using voltammetry in awake and anesthetized rats, we reveal an unprecedented synchrony of dopamine fluctuations between hemispheres. Via stimulation with amphetamine, we demonstrate functional cross-hemispheric projections in a hemiparkinsonian model. This previously undescribed capacity for interhemispheric dopamine signaling can precipitate new areas of inquiry. Future work may exploit properties of bilateral dopamine release to improve treatments for Parkinson’s disease, including deep brain stimulation

    Foundations for Relativistic Quantum Theory I: Feynman's Operator Calculus and the Dyson Conjectures

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    In this paper, we provide a representation theory for the Feynman operator calculus. This allows us to solve the general initial-value problem and construct the Dyson series. We show that the series is asymptotic, thus proving Dyson's second conjecture for QED. In addition, we show that the expansion may be considered exact to any finite order by producing the remainder term. This implies that every nonperturbative solution has a perturbative expansion. Using a physical analysis of information from experiment versus that implied by our models, we reformulate our theory as a sum over paths. This allows us to relate our theory to Feynman's path integral, and to prove Dyson's first conjecture that the divergences are in part due to a violation of Heisenberg's uncertainly relations

    Quantization of Dirac fields in static spacetime

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    On a static spacetime, the solutions of the Dirac equation are generated by a time-independent Hamiltonian. We study this Hamiltonian and characterize the split into positive and negative energy. We use it to find explicit expressions for advanced and retarded fundamental solutions and for the propagator. Finally, we use a fermion Fock space based on the positive/negative energy split to define a Dirac quantum field operator whose commutator is the propagator.Comment: LaTex2e, 17 page

    Effective Field Theory Program for Conformal Quantum Anomalies

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    The emergence of conformal states is established for any problem involving a domain of scales where the long-range, SO(2,1) conformally invariant interaction is applicable. Whenever a clear-cut separation of ultraviolet and infrared cutoffs is in place, this renormalization mechanism produces binding in the strong-coupling regime. A realization of this phenomenon, in the form of dipole-bound anions, is discussed.Comment: 15 pages. Expanded, with additional calculational details. To be published in Phys. Rev.
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