Tracking perception of the sounds of English

Contains fulltext : 127790.pdf (publisher's version ) (Open Access)Twenty American English listeners identified gated fragments of all 2288 possible English within-word and cross-word diphones, providing a total of 538 560 phoneme categorizations. The results show orderly uptake of acoustic information in the signal and provide a view of where information about segments occurs in time. Information locus depends on each speech sound's identity and phonological features. Affricates and diphthongs have highly localized information so that listeners' perceptual accuracy rises during a confined time range. Stops and sonorants have more distributed and gradually appearing information. The identity and phonological features (e. g., vowel vs consonant) of the neighboring segment also influences when acoustic information about a segment is available. Stressed vowels are perceived significantly more accurately than unstressed vowels, but this effect is greater for lax vowels than for tense vowels or diphthongs. The dataset charts the availability of perceptual cues to segment identity across time for the full phoneme repertoire of English in all attested phonetic context

Are Post-Newtonian templates faithful and effectual in detecting gravitational signals from neutron star binaries?

We compute the overlap function between Post-Newtonian (PN) templates and gravitational signals emitted by binary systems composed of one neutron star and one point mass, obtained by a perturbative approach. The calculations are performed for different stellar models and for different detectors, to estimate how effectual and faithful the PN templates are, and to establish whether effects related to the internal structure of neutron stars may possibly be extracted by the matched filtering technique.Comment: 14 pages, 3 figures, accepted for publication in Phys. Rev.

Measuring black-hole parameters and testing general relativity using gravitational-wave data from space-based interferometers

Among the expected sources of gravitational waves for the Laser Interferometer Space Antenna (LISA) is the capture of solar-mass compact stars by massive black holes residing in galactic centers. We construct a simple model for such a capture, in which the compact star moves freely on a circular orbit in the equatorial plane of the massive black hole. We consider the gravitational waves emitted during the late stages of orbital evolution, shortly before the orbiting mass reaches the innermost stable circular orbit. We construct a simple model for the gravitational-wave signal, in which the phasing of the waves plays the dominant role. The signal's behavior depends on a number of parameters, including $\mu$, the mass of the orbiting star, $M$, the mass of the central black hole, and $J$, the black hole's angular momentum. We calculate, using our simplified model, and in the limit of large signal-to-noise ratio, the accuracy with which these quantities can be estimated during a gravitational-wave measurement. Our simplified model also suggests a method for experimentally testing the strong-field predictions of general relativity.Comment: ReVTeX, 16 pages, 5 postscript figure

Gravitational signals emitted by a point mass orbiting a neutron star: effects of stellar structure

The effects that the structure of a neutron star would have on the gravitational emission of a binary system are studied in a perturbative regime, and in the frequency domain. Assuming that a neutron star is perturbed by a point mass moving on a close, circular orbit, we solve the equations of stellar perturbations in general relativity to evaluate the energy lost by the system in gravitational waves. We compare the energy output obtained for different stellar models with that found by assuming that the perturbed object is a black hole with the same mass, and we discuss the role played by the excitation of the stellar modes. Ouresults indicate that the stellar structure begins to affect the emitted power when the orbital velocity is v >0.2c (about 185 Hz for a binary system composed of two canonical neutron stars). We show that the differences between different stellar models and a black hole are due mainly to the excitation of the quasinormal modes of the star. Finally, we discuss to what extent and up to which distance the perturbative approach can be used to describe the interaction of a star and a pointlike massive body.Comment: 22 pages, 6 figures, to appear in Phys. Rev. D. Revised version, added one table and extended discussio

Accounting and social movements: An exploration of critical accounting praxis

A central tenet of critical accounting research maintains the need to challenge and change existing social relations; moving towards a more emancipated and equitable social order. The question of how critical accounting research upholds this principle has been intermittently discussed. This paper aims to engage with, and further, this discussion by contributing to research linking accounting information to social movements. The paper reviews the literature on accounting and social movements, central to which is the work of Gallhofer and Haslam; using their work as a departure point we discussion the nature of accounting information and focus on social movement unionism (SMU). Drawing on Bakhtinian dialogics and classical Marxism we develop an alternative theoretical framework to analyse an example of accounting information and social movements, covering a trade union pay dispute. The paper concludes with a discussion of the class nature of accounting information, including an exploration of the implications for accounting praxis and agency in the struggles for an emancipated world. The paper builds on the limited amount of existing work in this area; exploring the ‘class belongingness’ of accounting information and developing an understanding which can help guide the praxis of critical accounting researchers

Post-Newtonian Gravitational Radiation

1 Introduction 2 Multipole Decomposition 3 Source Multipole Moments 4 Post-Minkowskian Approximation 5 Radiative Multipole Moments 6 Post-Newtonian Approximation 7 Point-Particles 8 ConclusionComment: 46 pages, in Einstein's Field Equations and Their Physical Implications, B. Schmidt (Ed.), Lecture Notes in Physics, Springe

Crises and collective socio-economic phenomena: simple models and challenges

Financial and economic history is strewn with bubbles and crashes, booms and busts, crises and upheavals of all sorts. Understanding the origin of these events is arguably one of the most important problems in economic theory. In this paper, we review recent efforts to include heterogeneities and interactions in models of decision. We argue that the Random Field Ising model (RFIM) indeed provides a unifying framework to account for many collective socio-economic phenomena that lead to sudden ruptures and crises. We discuss different models that can capture potentially destabilising self-referential feedback loops, induced either by herding, i.e. reference to peers, or trending, i.e. reference to the past, and account for some of the phenomenology missing in the standard models. We discuss some empirically testable predictions of these models, for example robust signatures of RFIM-like herding effects, or the logarithmic decay of spatial correlations of voting patterns. One of the most striking result, inspired by statistical physics methods, is that Adam Smith's invisible hand can badly fail at solving simple coordination problems. We also insist on the issue of time-scales, that can be extremely long in some cases, and prevent socially optimal equilibria to be reached. As a theoretical challenge, the study of so-called "detailed-balance" violating decision rules is needed to decide whether conclusions based on current models (that all assume detailed-balance) are indeed robust and generic.Comment: Review paper accepted for a special issue of J Stat Phys; several minor improvements along reviewers' comment

Newborn Magnetars as sources of Gravitational Radiation: constraints from High Energy observations of Magnetar Candidates

Soft Gamma Repeaters and the Anomalous X-ray Pulsars are believed to contain slowly spinning "magnetars". The enormous energy liberated in the 2004 Dece 27 giant flare from SGR 1806-20, together with the likely recurrence time of such events, points to an internal magnetic field strength ~ 10^{16} G. Such strong fields are expected to be generated by a coherent alpha-Omega dynamo in the early seconds after the Neutron Star formation, if its spin period is of a few milliseconds at most. A substantial deformation of the NS is caused by such fields and a newborn millisecond-spinning magnetar would thus radiate for a few days a strong gravitational wave signal. Such a signal may be detected with Advanced LIGO-class detectors up to the distance of the Virgo cluster, where ~ 1 magnetar per year are expected to form. Recent X-ray observations reveal that SNRs around magnetar candidates do not show evidence for a larger energy content than standard SNRs (Vink & Kuiper 2006). This is at variance with what would be expected if the spin energy of the young, millisecond NS were radiated away as electromagnetic radiation andd/or relativistic particle winds and, thus, transferred quickly to the expanding gas shell. We show here that these recent findings can be reconciled with the idea of magnetars being formed with fast spins, if most of their initial spin energy is radiated thorugh GWs. In particular, we find that this occurs for essentially the same parameter range that would make such objects detectable by Advanced LIGO-class detectors up to the Virgo Cluster.Comment: Proceedings of the Conference "Isolated Neutron stars: from the interior to the surface", Eds. D. Page, R. Turolla, S. Zan

An f˙(f)\dot{f}(f)-frequency dynamics algorithm for gravitational waves

Coalescence of low mass compact binaries of neutron stars and black holes are primary burst sources for LIGO and VIRGO.Of importance in the early stages of observations will be the classification of candidate detections by source-type. The diversity in source parameters and serendipity in any new window of observations suggest to consider model-independent detection algorithms. Here a frequency dynamics algorithm is described which extracts a trajectory in the $\dot{f}(f)$-plane from the noisy signal. The algorithm is studied in simulated binary coalescence. Robust results are obtained with experimental noise data. Experiments show the method to be superior to matched filtering in the presence of model imperfections.Comment: to appear in Rapid Commun, Phys Rev