Weakly nonlinear waves in magnetized plasma with a slightly non-Maxwellian electron distribution. Part 1, Stability of solitary waves

Weakly nonlinear waves in strongly magnetized plasma with slightly non-isothermal electrons are governed by a modified Zakharov–Kuznetsov (ZK) equation, containing both quadratic and half-order nonlinear terms, which we refer to as the Schamel–Korteweg–de Vries–Zakharov–Kuznetsov (SKdVZK) equation. We present a method to obtain an approximation for the growth rate, γ, of sinusoidal perpendicular perturbations of wavenumber, k, to SKdVZK solitary waves over the entire range of instability. Unlike for (modified) ZK equations with one nonlinear term, in this method there is no analytical expression for kc, the cut-off wavenumber (at which the growth rate is zero) or its corresponding eigenfunction. We therefore obtain approximate expressions for these using an expansion parameter, a, related to the ratio of the nonlinear terms. The expressions are then used to find γ for k near kc as a function of a. The approximant derived from combining these analytical results with the ones for small k agrees very well with the values of γ obtained numerically. It is found that both kc and the maximum growth rate decrease as the electron distribution becomes progressively less peaked than the Maxwellian. We also present new algebraic and rarefactive solitary wave solutions to the equation

Improving production management

Production (Economic theory) ; Manufactures ; Inventories

Lean inventory corrections

Inventories

Domestic violence, sexual assault and stalking: findings from the British Crime Survey

Inter-personal violence comprises crimes of domestic violence, sexual assault and stalking. These are important forms of crime and the government is engaged in a major series of policy initiatives in order to deal with them. However, only a small fraction of these cases are reported to the police and recorded by them, and even interview based surveys have difficulty in getting people to disclose such events. This report presents the findings of an innovative computerised self-completion questionnaire included in the British Crime Survey (BCS) which encourages wider reporting of experiences than the main face-to-face part of the BCS. It builds on previous use of this methodology in the BCS, and provides the most reliable findings to date on the extent and nature of inter-personal violence in England and Wales

Seasonal production smoothing

Empirical tests of the production-smoothing hypothesis have yielded mixed results. In this paper, Donald Allen looks for, and finds evidence of, seasonal production smoothing in 15 out of 25 manufacturing series and 8 out of 10 retail series, using detrended seasonally unadjusted data. The equivalent test using seasonally adjusted data were negative for all 35 series. The results suggest that seasonally adjusted data obscure short-term production-smoothing.Business cycles ; Productivity ; Seasonal variations (Economics)

How closely do banks manage vault cash?

This article examines daily vault cash balances in the Eighth Federal Reserve District to see if banks have been optimizing their vault cash levels. Recent reductions in reserve requirements have not been accompanied by significant reductions in vault cash. This situation suggests that banks may be managing vault cash reserves primarily as precautionary balances to satisfy daily fluctuations in deposits and withdrawals, rather then part of total reserve management. In 1997, some larger banks instituted formal management of vault currency. If this practice spreads, it will have implications for monetary policy and cash operations.Bank reserves ; Cash management

Another soft inventory landing?

Inventories

Saving up: gross and personal

Saving and investment

Freshwater fish and crayfish communities of the tributaries of the Margaret River

Tributaries and headwaters of major rivers are known to be important spawning and nursery habitats of freshwater endemic fishes in south-western Australia (see for example the Collie River in Pen & Potter 1990, and the Blackwood River in Beatty et al. 2006, 2008). Fishes of the Margaret River have previously been examined by Morgan et al. (1998) and Morgan & Beatty (2003) with the monitoring of the functioning of the two fishways on the river documented in Morgan & Beatty (2004, 2007) and Beatty & Morgan (2008). The river is known to be of conservation importance due to it housing five of the eight endemic freshwater fishes of the south-west region, as well as housing the majority (five of the six species) of the Cherax species of freshwater crayfishes found in the south-west; including the Margaret River endemic Critically Endangered Hairy Marron. Despite this known value and considerable volume of research on the fishes in the main channel of the Margaret River, little is known on the fishes and freshwater crayfishes of the river 19s major tributaries. The aim of this study is to document the freshwater fish distribution in the major tributaries of the Margaret River (i.e. Bramley, Darch, and Yalgardup Brooks) during or close to the breeding period for the majority of the species and to provide a broad assessment and comparison of population demographics of the different species in the different tributaries. This information is required for the formulation of River Action Plans for these systems by the Cape to Cape Catchments Group