8,639 research outputs found
Decontextualizing contextual inversion
Contextual inversion, introduced as an analytical tool by David Lewin, is a concept of wide reach and value in music theory and analysis, at the root of neo-Riemannian theory as well as serial theory, and useful for a range of analytical applications. A shortcoming of contextual inversion as it is currently understood, however, is, as implied by the name, that the transformation has to be defined anew for each application. This is potentially a virtue, requiring the analyst to invest the transformational system with meaning in order to construct it in the first place. However, there are certainly instances where new transformational systems are continually redefined for essentially the same purposes. This paper explores some of the most common theoretical bases for contextual inversion groups and considers possible definitions of inversion operators that can apply across set class types, effectively decontextualizing contextual inversions.Accepted manuscrip
Modelling of Electroluminescence in Polymers Using a Bipolar Charge Transport Model
Electroluminescence (EL) in polymeric materials is thought to occur due to the energy dissipation process from the recombination of opposite polarity charge carriers. It is considered as an indication of storage and transport of charge carriers in cable insulation subject to electrical stresses and may indicate the change in charge movement due to aging or degradation processes. Under ac electric fields, the interaction of opposite polarity charge carriers at the interface of polymer/conductor is enhanced compared with dc conditions, and seems to contribute a lot to the electroluminescence rather than the charge behaviours in the bulk of polymers. The dynamics of charge carriers both at the interface of polymer/conductor and in the bulk of polymers is investigated through a simulation work using a bipolar charge transport model. Figure 1 compares experimental electroluminescence results with simulated data from the recombination of injected charge carriers. The paper will give more details on EL model and comparison under various waveforms and frequencies
Adherence to cardiac rehabilitation guidelines: a survey of rehabilitation programmes in the United Kingdom
Two key recommendations of recent guidelines are that cardiac rehabilitation requires the skills of a range of professionals and that the patient should receive a menu based programme after an individual assess ment of needs. A previous survey of 25 cardiac rehabilitation programmes found little congruence with these guidelines and noted that physicians were particularly unlikely to be involved. We extended this inquiry to include all of the discoverable rehabilitation programmes in the United Kingdom
Condition Monitoring of Power Cables
A National Grid funded research project at Southampton has investigated possible methodologies for data acquisition, transmission and processing that will facilitate on-line continuous monitoring of partial discharges in high voltage polymeric cable systems. A method that only uses passive components at the measuring points has been developed and is outlined in this paper. More recent work, funded through the EPSRC Supergen V, UK Energy Infrastructure (AMPerES) grant in collaboration with UK electricity network operators has concentrated on the development of partial discharge data processing techniques that ultimately may allow continuous assessment of transmission asset health to be reliably determined
Electronic structure and chemical bonding of nc-TiC/a-C nanocomposites
The electronic structure of nanocrystalline (nc-) TiC/amorphous C
nanocomposites has been investigated by soft x-ray absorption and emission
spectroscopy. The measured spectra at the Ti 2p and C 1s thresholds of the
nanocomposites are compared to those of Ti metal and amorphous C. The
corresponding intensities of the electronic states for the valence and
conduction bands in the nanocomposites are shown to strongly depend on the TiC
carbide grain size. An increased charge-transfer between the Ti 3d-eg states
and the C 2p states has been identified as the grain size decreases, causing an
increased ionicity of the TiC nanocrystallites. It is suggested that the
charge-transfer occurs at the interface between the nanocrystalline TiC and the
amorphous C matrix and represents an interface bonding which may be essential
for the understanding of the properties of nc-TiC/amorphous C and similar
nanocomposites.Comment: 13 pages, 6 figures, 1 table;
http://link.aps.org/doi/10.1103/PhysRevB.80.23510
Next-to-leading Log Resummation of Scalar and Pseudoscalar Higgs Boson Differential Cross-Sections at the LHC and Tevatron
The region of small transverse momentum in q qbar- and gg-initiated processes
must be studied in the framework of resummation to account for the large,
logarithmically-enhanced contributions to physical observables. In this paper,
we will calculate the fixed order next-to-leading order (NLO) perturbative
total and differential cross-sections for both a Standard Model (SM) scalar
Higgs boson and the Minimal Supersymmetric Standard Model's (MSSM) pseudoscalar
Higgs boson in the Heavy Quark Effective Theory (HQET) where the mass of the
top quark is taken to be infinite. Resummation coefficients B^2_g, C^2_gg for
the total cross-section resummation for the pseudoscalar case are given, as
well as C^1_gg for the differential cross-section.Comment: 18 pages, REVTeX4, 5 eps figures. v2: Typos corrected, references
added, a discussion of uncertainties was adde
Eddington-limited X-ray Bursts as Distance Indicators. I. Systematic Trends and Spherical Symmetry in Bursts from 4U 1728-34
We investigate the limitations of thermonuclear X-ray bursts as a distance
indicator for the weakly-magnetized accreting neutron star 4U 1728-34. We
measured the unabsorbed peak flux of 81 bursts in public data from the Rossi
X-Ray Timing Explorer (RXTE). The distribution of peak fluxes was bimodal: 66
bursts exhibited photospheric radius expansion and were distributed about a
mean bolometric flux of 9.2e-8 erg/cm^2/s, while the remaining (non-radius
expansion) bursts reached 4.5e-8 erg/cm^2/s, on average. The peak fluxes of the
radius-expansion bursts were not constant, exhibiting a standard deviation of
9.4% and a total variation of 46%. These bursts showed significant correlations
between their peak flux and the X-ray colors of the persistent emission
immediately prior to the burst. We also found evidence for quasi-periodic
variation of the peak fluxes of radius-expansion bursts, with a time scale of
approximately 40 d. The persistent flux observed with RXTE/ASM over 5.8 yr
exhibited quasi-periodic variability on a similar time scale. We suggest that
these variations may have a common origin in reflection from a warped accretion
disk. Once the systematic variation of the peak burst fluxes is subtracted, the
residual scatter is only approximately 3%, roughly consistent with the
measurement uncertainties. The narrowness of this distribution strongly
suggests that i) the radiation from the neutron star atmosphere during
radius-expansion episodes is nearly spherically symmetric, and ii) the
radius-expansion bursts reach a common peak flux which may be interpreted as a
standard candle intensity.Adopting the minimum peak flux for the
radius-expansion bursts as the Eddington flux limit, we derive a distance for
the source of 4.4-4.8 kpc.Comment: 9 pages, 7 figures, accepted by ApJ. Minor referee's revisions, also
includes 9 newly public X-ray burst
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