684 research outputs found
Synchronic variation in the expression of French negation - a Distributed Morphology approach
This article discusses ne-variation in French sentential negation based on the phonologically transcribed corpus T-zéro (cf. Meisner, in preparation) which allows a new interpretation of the facts. In the last decades, sociolinguistic and stylistic approaches to linguistic variation in French (cf. Armstrong, 2001) have shown that extra-linguistic factors, such as the speaker's age, sex, social background or geographic origin as well as the communication situation may have considerable influence on variable ne-omission. However, in contrast to most sociolinguistic studies dedicated to this phenomenon (cf. Ashby, 1976, 1981, 2001; Armstrong and Smith, 2002; Coveney, 2002) we will focus on the linguistic factors influencing ne-variation, since their importance is empirically evident but not yet fully exploited on a theoretical level.
One leading assumption with respect to ne-variation in literature is that the particle ne is most frequently retained in combination with a proper name or a full DP and is commonly omitted when combined with clitic subjects. However, there are many exceptions to this rule which, as we argue, can be better explained by considering the phonological form of the involved subject. Ne-realisation is treated here as an inner-grammatical phenomenon that is triggered by context sensitivity with regard to the element to its left, i.e. usually the grammatical subject, and not as a consequence of âcode-switchingâ between two grammars nor as a sociolinguistic variable characterising certain groups of speakers in the Labovian sense (cf. Labov, 1972), since we seek to describe general variational tendencies, present in nearly all speakers of contemporary European French. Our analysis, which is implemented in a Distributed Morphology framework (Halle & Marantz, 1994), is compatible, however, with stylistic approaches to ne-variation, such as audience design (cf. Bell, 1984, 2001)
Non-dissipative Thermal Transport and Magnetothermal Effect for the Spin-1/2 Heisenberg Chain
Anomalous magnetothermal effects are discussed in the spin-1/2 Heisenberg
chain. The energy current is related to one of the non-trivial conserved
quantities underlying integrability and therefore both the diagonal and off
diagonal dynamical correlations of spin and energy current diverge. The
energy-energy and spin-energy current correlations at finite temperatures are
exactly calculated by a lattice path integral formulation. The low-temperature
behavior of the thermomagnetic (magnetic Seebeck) coefficient is also
discussed. Due to effects of strong correlations, we observe the magnetic
Seebeck coefficient changes sign at certain interaction strengths and magnetic
fields.Comment: 4 pages, references added, typos corrected, Conference proceedings of
SPQS 2004, Sendai, Japa
Thermomagnetic Power and Figure of Merit for Spin-1/2 Heisenberg Chain
Transport properties in the presence of magnetic fields are numerically
studied for the spin-1/2 Heisenberg XXZ chain. The breakdown of the
spin-reversal symmetry due to the magnetic field induces the magnetothermal
effect. In analogy with the thermoelectric effect in electron systems, the
thermomagnetic power (magnetic Seebeck coefficient) is provided, and is
numerically evaluated by the exact diagonalization for wide ranges of
temperatures and various magnetic fields. For the antiferromagnetic regime, we
find the magnetic Seebeck coefficient changes sign at certain temperatures,
which is interpreted as an effect of strong correlations. We also compute the
thermomagnetic figure of merit determining the efficiency of the thermomagnetic
devices for cooling or power generation.Comment: 8 page
Finite size effects on transport coefficients for models of atomic wires coupled to phonons
We consider models of quasi-1-d, planar atomic wires consisting of several,
laterally coupled rows of atoms, with mutually non-interacting electrons. This
electronic wire system is coupled to phonons, corresponding, e.g., to some
substrate. We aim at computing diffusion coefficients in dependence on the wire
widths and the lateral coupling. To this end we firstly construct a numerically
manageable linear collision term for the dynamics of the electronic occupation
numbers by following a certain projection operator approach. By means of this
collision term we set up a linear Boltzmann equation. A formula for extracting
diffusion coefficients from such Boltzmann equations is given. We find in the
regime of a few atomic rows and intermediate lateral coupling a significant and
non-trivial dependence of the diffusion coefficient on both, the width and the
lateral coupling. These results, in principle, suggest the possible
applicability of such atomic wires as electronic devices, such as, e.g.,
switches.Comment: 9 pages, 5 figures, accepted for publication in Eur. Phys. J.
Optical Properties of MFe_4P_12 filled skutterudites
Infrared reflectance spectroscopy measurements were made on four members of
the MFe_4P_12 family of filled skutterudites, with M=La, Th, Ce and U. In
progressing from M=La to U the system undergoes a metal-insulator transition.
It is shown that, although the filling atom induces such dramatic changes in
the transport properties of the system, it has only a small effect on lattice
dynamics. We discuss this property of the compounds in the context of their
possible thermoelectric applications.Comment: Manuscript in ReVTeX format, 7 figures in PostScirpt forma
Superconductivity and the high field ordered phase in the heavy fermion compound PrOsSb
Superconductivity is observed in the filled skutterudite compound \PrOsSb{}
below a critical temperature temperature K and appears to
develop out of a nonmagnetic heavy Fermi liquid with an effective mass , where is the free electron mass.
Features associated with a cubic crystalline electric field are present in
magnetic susceptibility, specific heat, electrical resistivity, and inelastic
neutron scattering measurements, yielding a Pr energy level scheme
consisting of a nonmagnetic doublet ground state, a low lying
triplet excitied state at K, and much higher temperature
triplet and singlet excited states. Measurements also
indicate that the superconducting state is unconventional and consists of two
distinct superconducting phases. At high fields and low temperatures, an
ordered phase of magnetic or quadrupolar origin is observed, suggesting that
the superconductivity may occur in the vicinity of a magnetic or quadrupolar
quantum critical point.Comment: 11 pages, 4 figures, presented at the 3rd international symposium on
Advance Science Research (ASR 2002), JAERI Tokai, Ibaraki, Japa
Revisiting the reactivity between HCO and CH on interstellar grain surfaces
Formation of interstellar complex organic molecules is currently thought to
be dominated by the barrierless coupling between radicals on the interstellar
icy grain surfaces. Previous standard DFT results on the reactivity between
CH and HCO on amorphous water surfaces, showed that formation of CH +
CO by H transfer from HCO to CH assisted by water molecules of the ice was
the dominant channel. However, the adopted description of the electronic
structure of the biradical (i.e., CH/HCO) system was inadequate (without
the broken-symmetry (BS) approach). In this work, we revisit the original
results by means of BS-DFT both in gas phase and with one water molecule
simulating the role of the ice. Results indicate that adoption of BS-DFT is
mandatory to describe properly biradical systems. In the presence of the single
water molecule, the water-assisted H transfer exhibits a high energy barrier.
In contrast, CHCHO formation is found to be barrierless. However, direct H
transfer from HCO to CH to give CO and CH presents a very low energy
barrier, hence being a potential competitive channel to the radical coupling
and indicating, moreover, that the physical insights ofthe original work remain
valid.Comment: Submitted to MNRAS main journal. For associated supporting material
refer to the publication in MNRAS. Accepted 2020 February 14. Received 2020
February 1
Calculation of Optical Conductivity of YbB using Realistic Tight-Binding Model
Based on the previously reported tight-binding model fitted to the LDA+U band
calculation, optical conductivity of the prototypical Kondo insulator
YbB is calculated theoretically. Many-body effects are taken into
account by the self-consistent second order perturbation theory. The gross
shape of the optical conductivity observed in experiments are well described by
the present calculation, including their temperature-dependences.Comment: 6 pages, 7 figures, use jpsj2.cls, to appear in J. Phys. Soc. Jpn.
Vol.73, No.10 (2004
Thermal conductivity via magnetic excitations in spin-chain materials
We discuss the recent progress and the current status of experimental
investigations of spin-mediated energy transport in spin-chain and spin-ladder
materials with antiferromagnetic coupling. We briefly outline the central
results of theoretical studies on the subject but focus mainly on recent
experimental results that were obtained on materials which may be regarded as
adequate physical realizations of the idealized theoretical model systems. Some
open questions and unsettled issues are also addressed.Comment: 17 pages, 4 figure
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