14,818 research outputs found
Reduction of word-final obstruent-liquid-schwa clusters in Parisian French
This corpus study investigated pronunciation variants of word-final obstruent-liquid-schwa (OLS) clusters in nouns in casual Parisian French. Results showed that at least one phoneme was absent in 80.7% of the 291 noun tokens in the dataset, and that the whole cluster was absent (e.g., [mis] for ministre) in no less than 15.5% of the tokens. We demonstrate that phonemes are not always completely absent, but that they may leave traces on neighbouring phonemes. Further, the clusters display undocumented voice assimilation patterns. Statistical modelling showed that a phoneme is most likely to be absent if the following phoneme is also absent. The durations of the phonemes are conditioned particularly by the position of the word in the prosodic phrase. We argue, on the basis of three different types of evidence, that in French word-final OLS clusters, the absence of obstruents is mainly due to gradient reduction processes, whereas the absence of schwa and liquids may also be due to categorical deletion processes
A Multi-Modal Continuous-Systems Model of a Novel High-Q Disk Resonator in a Viscous Liquid
International audienc
Proper Motion of Pulsar B1800-21
We report high angular resolution, multi-epoch radio observations of the
young pulsar PSR B1800-21. Using two pairs of data sets, each pair spanning
approximately a ten year period, we calculate the proper motion of the pulsar.
We obtain a proper motion of mu_alpha=11.6 +- 1.8 mas/yr, mu_delta=14.8 +- 2.3
mas/yr, which clearly indicates a birth position at the extreme edge of the W30
supernova remnant. Although this does not definitively rule out an association
of W30 and PSR B1800-21, it does not support an association.Comment: 13 pages, 1 color figure. Replaced with version accepted for
publication in Astrophysical Journa
Geometrical Optimization of Resonant Cantilevers Vibrating in In-Plane Bending Modes
The influence of the beam geometry on the quality factor and resonance frequency of resonant silicon cantilever beams vibrating in their fundamental in-plane flexural mode has been investigated in air and water. Compared to cantilevers vibrating in their out-of-plane flexural mode, utilizing the in plane mode results in reduced damping and reduced mass loading by the surrounding fluid. Quality factors as high as 4,300 in air and 67 in water have been measured for cantilevers with a 12 Ī¼m thick silicon layer. This is in comparison to Q factors up to 1,500 in air and up to 20 in water for cantilevers vibrating in their fundamental out-of-plane bending mode. Based on the experimental data, design guidelines are established for beam dimensions that ensure maximal Q-factors and minimal mass loading by the surrounding fluid
Analytical Modeling of a Novel High-\u3cem\u3eQ\u3c/em\u3e Disk Resonator for Liquid-Phase Applications
To overcome the detrimental effects of liquid environments on microelectromechanical systems resonator performance, the in-fluid vibration of a novel disk resonator supported by two electrothermally driven legs is investigated through analytical modeling and the effects of the systemās geometric/material parameters on the dynamic response are explored. The all-shear interaction device (ASID) is based on engaging the surrounding fluid primarily through shearing action. The theory comprises a continuous-system, multimodal model, and a single-degree-of-freedom model, the latter yielding simple formulas for the fundamental-mode resonant characteristics that often furnish excellent estimates to the results based on the more general model. Comparisons between theoretical predictions and previously published liquid-phase quality factor (Q) data (silicon devices in heptane) show that the theoretical results capture the observed trends and also give very good quantitative estimates, particularly for the highest Q devices. Moreover, the highest Q value measured in the earlier study (304) corresponded to a specimen whose disk radius-to-thickness ratio was 2.5, a value that compares well with the optimal value of 2.3 predicted by the present model. The insight furnished by the proposed theory is expected to lead to further improvements in ASID design to achieve unprecedented levels of performance for a wide variety of liquid-phase resonator applications
Different evolutionary stages in massive star formation. Centimeter continuum and H2O maser emission with ATCA
We present ATCA observations of the H2O maser line and radio continuum at
18.0GHz and 22.8GHz, toward a sample of 192 massive star forming regions
containing several clumps already imaged at 1.2mm. The main aim of this study
is to investigate the water maser and centimeter continuum emission (likely
tracing thermal free-free emission) in sources at different evolutionary
stages, using the evolutionary classifications proposed by Palla et al (1991)
and Molinari et al (2008). We used the recently comissioned CABB backend at
ATCA obtaining images with 20arcsec resolution in the 1.3cm continuum and H2O
maser emission, in all targets. For the evolutionary analysis of the sources we
used the millimeter continuum emission from Beltran et al (2006) and the
infrared emission from the MSX Point Source Catalogue. We detect centimeter
continuum emission in 88% of the observed fields with a typical rms noise level
of 0.45mJy/beam. Most of the fields show a single radio continuum source, while
in 20% of them we identify multiple components. A total of 214 centimeter
continuum sources have been identified, likely tracing optically thin HII
regions, with physical parameters typical of both extended and compact HII
regions. Water maser emission was detected in 41% of the regions, resulting in
a total of 85 distinct components. The low angular (20arcsec) and spectral
(14km/s) resolutions do not allow a proper analysis of the water maser
emission, but suffice to investigate its association with the continuum
sources. We have also studied the detection rate of HII regions in the two
types of IRAS sources defined by Palla et (1991) on the basis of the IRAS
colours: High and Low. No significant differences are found, with large
detection rates (>90%) for both High and Low sources. We classify the
millimeter and infrared sources in our fields in three evolutionary stages
following the scheme presented by ...Comment: 102 pages, 19 figures, 10 tables, accepted for publication in
Astronomy & Astrophysic
Is there something of the MCT in orientationally disordered crystals ?
Molecular Dynamics simulations have been performed on the orientationally
disordered crystal chloroadamantane: a model system where dynamics are almost
completely controlled by rotations. A critical temperature T_c = 225 K as
predicted by the Mode Coupling Theory can be clearly determined both in the
alpha and beta dynamical regimes. This investigation also shows the existence
of a second remarkable dynamical crossover at the temperature T_x > T_c
consistent with a previous NMR and MD study [1]. This allows us to confirm
clearly the existence of a 'landscape-influenced' regime occurring in the
temperature range [T_c-T_x] as recently proposed [2,3].Comment: 4 pages, 5 figures, REVTEX
Evolving a DSL implementation
Domain Specific Languages (DSLs) are small languages designed for use in a specific domain. DSLs typically evolve quite radically throughout their lifetime, but current DSL implementation approaches are often clumsy in the face of such evolution. In this paper I present a case study of an DSL evolving in its syntax, semantics, and robustness, implemented in the Converge language. This shows how real-world DSL implementations can evolve along with changing requirements
On the Relative Sensitivity of Mass-sensitive Chemical Microsensors
In this work, the chemical sensitivity of mass-sensitive chemical microsensors with a uniform layer sandwich structure vibrating in their lateral or in-plane flexural modes is investigated. It is experimentally verified that the relative chemical sensitivity of such resonant microsensors is -to a first order- independent of the microstructure\u27s in-plane dimensions and the flexural eigenmode used, and only depends on the layer thicknesses and densities as well as the sorption properties of the sensing film. Important implications for the design of mass-sensitive chemical microsensors are discussed, whereby the designer can focus on the layer stack to optimize the chemical sensitivity and on the in-plane dimensions and mode shape to optimize the resonator\u27s frequency stability
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