1,411 research outputs found
A more representative chamber: representation and the House of Lords
Since 1997 there has been substantive reform of the House of Lords in an effort to make the chamber âmore democratic and more representativeâ. Whilst the Labour government failed to press ahead with any of the proposed plans for further reform following the removal of the bulk of the hereditary peers in 1999, it remained committed to the notion that such reform must make the second chamber âmore representativeâ. The coalition government's programme advocates a long-term aspiration for a House wholly or mainly elected on the basis of proportional representation, and a short-term approach based on additional appointments to ensure a balance of the parties. What is clear in all of these proposals for reform is a desire for the House of Lords to become more representative than it is at present. However, what is less clear is what is meant by ârepresentativeâ â who the House of Lords is supposed to represent, and what form representation will take. Moreover, in proposing to make the chamber more representative, either through appointment or election, little attention has been paid to how the current House of Lords provides representation. This article examines these questions in the context of Pitkin's classic conceptions of representation and peers' attitudes towards their own representative rol
Searching for gravitational waves from the Crab pulsar - the problem of timing noise
Of the current known pulsars, the Crab pulsar (B0531+21) is one of the most
promising sources of gravitational waves. The relatively large timing noise of
the Crab causes its phase evolution to depart from a simple spin-down model.
This effect needs to be taken in to account when performing time domain
searches for the Crab pulsar in order to avoid severely degrading the search
efficiency. The Jodrell Bank Crab pulsar ephemeris is examined to see if it can
be used for tracking the phase evolution of any gravitational wave signal from
the pulsar, and we present a method of heterodyning the data that takes account
of the phase wander. The possibility of obtaining physical information about
the pulsar from comparisons of the electromagnetically and a gravitationally
observed timing noise is discussed. Finally, additional problems caused by
pulsar glitches are discussed.Comment: 5 pages, 1 figure, Proceedings of the 5th Amaldi Conference on
Gravitational Waves, Pisa, Italy, 6-11 July 200
Advanced technologies for future ground-based, laser-interferometric gravitational wave detectors
We present a review of modern optical techniques being used and developed for the field of gravitational wave detection. We describe the current state-of-the-art of gravitational waves detector technologies with regard to optical layouts, suspensions and test masses. We discuss the dominant sources and noise in each of these subsystems and the developments that will help mitigate them for future generations of detectors. We very briefly summarise some of the novel astrophysics that will be possible with these upgraded detectors
The declining representativeness of the British party system, and why it matters
In a recent article, Michael Laver has explained âWhy Vote-Seeking Parties May Make Voters Miserableâ. His model shows that, while ideological convergence may boost congruence between governments and the median voter, it can reduce congruence between the party system and the electorate as a whole. Specifically, convergence can increase the mean distance between voters and their nearest party. In this article we show that this captures the reality of todayâs British party system. Policy scale placements in British Election Studies from 1987 to 2010 confirm that the pronounced convergence during the past decade has left the Conservatives and Labour closer together than would be optimal in terms of minimising the policy distance between the average voter and the nearest major party. We go on to demonstrate that this comes at a cost. Respondents who perceive themselves as further away from one of the major parties in the system tend to score lower on satisfaction with democracy. In short, vote-seeking parties have left the British party system less representative of the ideological diversity in the electorate, and thus made at least some British voters miserable
'Word from the street' : when non-electoral representative claims meet electoral representation in the United Kingdom
Taking the specific case of street protests in the UK â the âword from the streetââ this article examines recent (re)conceptualizations of political representation, most particularly Sawardâs notion of ârepresentative claimâ. The specific example of nonelectoral claims articulated by protestors and demonstrators in the UK is used to illustrate: the processes of making, constituting, evaluating and accepting claims for and by constituencies and audiences; and the continuing distinctiveness of claims based upon electoral representation. Two basic questions structure the analysis: first, why would the political representative claims of elected representatives trump the nonelectoral claims of mass demonstrators and, second, in what ways does the âperceived legitimacyâ of the former differ from the latter
Misspecified Mean Function Regression: Making Good Use of Regression Models That Are Wrong
There are over three decades of largely unrebutted criticism of regression analysis as practiced in the social sciences. Yet, regression analysis broadly construed remains for many the method of choice for characterizing conditional relationships. One possible explanation is that the existing alternatives sometimes can be seen by researchers as unsatisfying. In this article, we provide a different formulation. We allow the regression model to be incorrect and consider what can be learned nevertheless. To this end, the search for a correct model is abandoned. We offer instead a rigorous way to learn from regression approximations. These approximations, not âthe truth,â are the estimation targets. There exist estimators that are asymptotically unbiased and standard errors that are asymptotically correct even when there are important specification errors. Both can be obtained easily from popular statistical packages
Inferring Core-Collapse Supernova Physics with Gravitational Waves
Stellar collapse and the subsequent development of a core-collapse supernova
explosion emit bursts of gravitational waves (GWs) that might be detected by
the advanced generation of laser interferometer gravitational-wave
observatories such as Advanced LIGO, Advanced Virgo, and LCGT. GW bursts from
core-collapse supernovae encode information on the intricate multi-dimensional
dynamics at work at the core of a dying massive star and may provide direct
evidence for the yet uncertain mechanism driving supernovae in massive stars.
Recent multi-dimensional simulations of core-collapse supernovae exploding via
the neutrino, magnetorotational, and acoustic explosion mechanisms have
predicted GW signals which have distinct structure in both the time and
frequency domains. Motivated by this, we describe a promising method for
determining the most likely explosion mechanism underlying a hypothetical GW
signal, based on Principal Component Analysis and Bayesian model selection.
Using simulated Advanced LIGO noise and assuming a single detector and linear
waveform polarization for simplicity, we demonstrate that our method can
distinguish magnetorotational explosions throughout the Milky Way (D <~ 10kpc)
and explosions driven by the neutrino and acoustic mechanisms to D <~ 2kpc.
Furthermore, we show that we can differentiate between models for rotating
accretion-induced collapse of massive white dwarfs and models of rotating iron
core collapse with high reliability out to several kpc.Comment: 22 pages, 9 figure
Models as Approximations - A Conspiracy of Random Regressors and Model Deviations Against Classical Inference in Regression
More than thirty years ago Halbert White inaugurated a âmodelrobustâ form of statistical inference based on the âsandwich estimatorâ of standard error. It is asymptotically correct even under âmodel misspecification,â that is, when models are approximations rather than generative truths. It is well-known to be âheteroskedasticity-consistentâ, but it is less well-known to be ânonlinearity-consistentâ as well. Nonlinearity, however, raises fundamental issues: When fitted models are approximations, conditioning on the regressor is no longer permitted because the ancillarity argument that justifies it breaks down. Two effects occur: (1) parameters become dependent on the regressor distribution; (2) the sampling variability of parameter estimates no longer derives from the conditional distribution of the response alone. Additional sampling variability arises when the nonlinearity conspires with the randomness of the regressors to generate a 1/ â N contribution to standard errors. Asymptotically, standard errors from âmodel-trustingâ fixedregressor theories can deviate from those of âmodel-robustâ randomregressor theories by arbitrary magnitudes. In the case of linear models, a test will be proposed for comparing the two types of standard error
Gravitational wave detection using pulsars: status of the Parkes Pulsar Timing Array project
The first direct detection of gravitational waves may be made through
observations of pulsars. The principal aim of pulsar timing array projects
being carried out worldwide is to detect ultra-low frequency gravitational
waves (f ~ 10^-9 to 10^-8 Hz). Such waves are expected to be caused by
coalescing supermassive binary black holes in the cores of merged galaxies. It
is also possible that a detectable signal could have been produced in the
inflationary era or by cosmic strings. In this paper we review the current
status of the Parkes Pulsar Timing Array project (the only such project in the
Southern hemisphere) and compare the pulsar timing technique with other forms
of gravitational-wave detection such as ground- and space-based interferometer
systems.Comment: Accepted for publication in PAS
The Sensitivity of the Parkes Pulsar Timing Array to Individual Sources of Gravitational Waves
We present the sensitivity of the Parkes Pulsar Timing Array to gravitational
waves emitted by individual super-massive black-hole binary systems in the
early phases of coalescing at the cores of merged galaxies. Our analysis
includes a detailed study of the effects of fitting a pulsar timing model to
non-white timing residuals. Pulsar timing is sensitive at nanoHertz frequencies
and hence complementary to LIGO and LISA. We place a sky-averaged constraint on
the merger rate of nearby () black-hole binaries in the early phases
of coalescence with a chirp mass of 10^{10}\,\rmn{M}_\odot of less than one
merger every seven years. The prospects for future gravitational-wave astronomy
of this type with the proposed Square Kilometre Array telescope are discussed.Comment: fixed error in equation (4). [13 pages, 6 figures, 1 table, published
in MNRAS
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