Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

Security Choice, Information Effects and Firm Characteristics: A Factor Analytic Approach

Abstract:  We examine the marginal choice between debt and equity securities using a factor analytic approach. This data reduction property eliminates the need to select the one best variable to proxy for a particular theoretical construct. Our results reinforce numerous existing findings using traditional methods and suggest both static tradeoff and asymmetric information based considerations are relevant in determining security choice. Two new results are presented related to the accounting liquidity of the firm. First, the preference for equity is increasing with liquidity as suggested by the window of opportunity hypothesis. Secondly, the market response to equity issuance announcements is inversely related to the liquidity of the firm. Profitability and growth measures support Jensen's (1986) agency cost of free cash flow as a potential explanation for the second finding. Copyright Blackwell Publishers Ltd, 2004.

The determinants of credit ratings in the United Kingdom insurance industry

This paper examines the determinants of external credit ratings attained by insurance firms in the United Kingdom (UK) and of the likelihood that insurers will have such an assessment. Using panel data relating to A.M. Best-rated and Standard and Poor's (S&P)-rated insurers over the period 1993-1997, a trichotomous logit model and an ordered probit model with sample selection are employed to show that the factors which influence the likelihood of having external credit assessments not only vary between the two agencies but also differ from those which determine the ratings themselves. Our results are shown to be of potential interest to participants in the insurance industry and policy-makers alike. Copyright Blackwell Publishers Ltd, 2002.