740 research outputs found

    A Better Interpretation of the Wrongful Death Act

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    A viable fetus is not a person under the wrongful death act, declared the Maine Law Court in a controversial decision in 1988. To reach this conclusion, the court employed one traditional and one new rule of statutory interpretation, and one traditional rule of law. The traditional rule of interpretation-that the wrongful death act is to be strictly construed because it is in derogation of the common law-dates from the earliest wrongful death cases heard by the court. The new rule of interpretation-that the death statute must be harmonized with the Maine Uniform Probate Code-derives from the enactment of the Code in 1981 and the placement of the wrongful death statute within it. The traditional rule of law-that recovery for wrongful death is exclusively governed by the terms of the wrongful death statute-is related to the rule of strict construction, but is based specifically on a mid-nineteenth century case that held the common law did not allow recovery for wrongful death. The Law Court has consistently held since then that the common law in Maine does not allow recovery for wrongful death, and, therefore, that the statute provides the sole basis for recovery. This Article argues that all three rules should be discarded. Instead of the three rules above, the Law Court should adopt a rule of fair construction, one which involves the court in a purposive analysis of the terms and provisions of the act without the presumption against coverage or application in the doubtful case that is at the heart of the rule of strict construction and without the fiction, integral to the rule, that any statutory terms are so clear and unambiguous that interpretation is unnecessary

    Solitonic Excitations in Linearly Coherent Channels of Bilayer Quantum Hall Stripes

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    In some range of interlayer distances, the ground state of the two-dimensional electron gas at filling factor nu =4N+1 with N=0,1,2,... is a coherent stripe phase in the Hartree-Fock approximation. This phase has one-dimensional coherent channels that support charged excitations in the form of pseudospin solitons. In this work, we compute the transport gap of the coherent striped phase due to the creation of soliton-antisoliton pairs using a supercell microscopic unrestricted Hartree-Fock approach. We study this gap as a function of interlayer distance and tunneling amplitude. Our calculations confirm that the soliton-antisoliton excitation energy is lower than the corresponding Hartree-Fock electron-hole pair energy. We compare our results with estimates of the transport gap obtained from a field-theoretic model valid in the limit of slowly varying pseudospin textures.Comment: 15 pages, 8 figure

    Dynamical matrix of two-dimensional electron crystals

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    In a quantizing magnetic field, the two-dimensional electron (2DEG) gas has a rich phase diagram with broken translational symmetry phases such as Wigner, bubble, and stripe crystals. In this paper, we derive a method to get the dynamical matrix of these crystals from a calculation of the density response function performed in the Generalized Random Phase Approximation (GRPA). We discuss the validity of our method by comparing the dynamical matrix calculated from the GRPA with that obtained from standard elasticity theory with the elastic coefficients obtained from a calculation of the deformation energy of the crystal.Comment: Revised version published in Phys. Rev. B. 12 pages with 11 postscripts figure

    Electrical transport through a single-electron transistor strongly coupled to an oscillator

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    We investigate electrical transport through a single-electron transistor coupled to a nanomechanical oscillator. Using a combination of a master-equation approach and a numerical Monte Carlo method, we calculate the average current and the current noise in the strong-coupling regime, studying deviations from previously derived analytic results valid in the limit of weak-coupling. After generalizing the weak-coupling theory to enable the calculation of higher cumulants of the current, we use our numerical approach to study how the third cumulant is affected in the strong-coupling regime. In this case, we find an interesting crossover between a weak-coupling transport regime where the third cumulant heavily depends on the frequency of the oscillator to one where it becomes practically independent of this parameter. Finally, we study the spectrum of the transport noise and show that the two peaks found in the weak-coupling limit merge on increasing the coupling strength. Our calculation of the frequency-dependence of the noise also allows to describe how transport-induced damping of the mechanical oscillations is affected in the strong-coupling regime.Comment: 11 pages, 9 figure

    Anisotropic states of two-dimensional electrons in high magnetic fields

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    We study the collective states formed by two-dimensional electrons in Landau levels of index n≥2n\ge 2 near half-filling. By numerically solving the self-consistent Hartree-Fock (HF) equations for a set of oblique two-dimensional lattices, we find that the stripe state is an anisotropic Wigner crystal (AWC), and determine its precise structure for varying values of the filling factor. Calculating the elastic energy, we find that the shear modulus of the AWC is small but finite (nonzero) within the HF approximation. This implies, in particular, that the long-wavelength magnetophonon mode in the stripe state vanishes like q3/2q^{3/2} as in an ordinary Wigner crystal, and not like q5/2q^{5/2} as was found in previous studies where the energy of shear deformations was neglected.Comment: minor corrections; 5 pages, 4 figures; version to be published in Physical Review Letter

    Universal properties of correlation transfer in integrate-and-fire neurons

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    One of the fundamental characteristics of a nonlinear system is how it transfers correlations in its inputs to correlations in its outputs. This is particularly important in the nervous system, where correlations between spiking neurons are prominent. Using linear response and asymptotic methods for pairs of unconnected integrate-and-fire (IF) neurons receiving white noise inputs, we show that this correlation transfer depends on the output spike firing rate in a strong, stereotyped manner, and is, surprisingly, almost independent of the interspike variance. For cells receiving heterogeneous inputs, we further show that correlation increases with the geometric mean spiking rate in the same stereotyped manner, greatly extending the generality of this relationship. We present an immediate consequence of this relationship for population coding via tuning curves

    Fermi-surface reconstruction and two-carrier model for the Hall effect in YBa2Cu4O8

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    Pulsed field measurements of the Hall resistivity and magnetoresistance of underdoped YBa2Cu4O8 are analyzed self-consistently using a simple model based on coexisting electron and hole carriers. The resultant mobilities and Hall numbers are found to vary markedly with temperature. The conductivity of the hole carriers drops by one order of magnitude below 30 K, explaining the absence of quantum oscillations from these particular pockets. Meanwhile the Hall coefficient of the electron carriers becomes strongly negative below 50 K. The overall quality of the fits not only provides strong evidence for Fermi-surface reconstruction in Y-based cuprates, it also strongly constrains the type of reconstruction that might be occurring.Comment: 5 pages, 4 figures, updated after publication in Physical Review B (Rapid Communication
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