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

Proposed revisions to the serological typing system for Treponema hyodysenteriae

Antisera were prepared in rabbits against seven well-characterized strains of Treponema hyodysenteriae of known serotype, and reacted in agarose gel double immunodiffusion tests (AGDP) with lipopolysaccharide (LPS) extracted from 18 Western Australian isolates of the organism. Eight isolates were provisionally typed by this method, but sera raised against one ‘typed’ and two ‘untypable’ local isolates reacted in an unexpected fashion with LPS from other local and type strains. Serum raised against the ‘typed’ local isolate reached with LPS from other previously untyped local isolates: this indicated the presence of more than one major LPS antigen amongst certain local isolates, and was confirmed by cross-absorption of sera. Sera raised against apparently untypable local isolates reacted with LPS from certain type organisms, thus suggesting the presence of complex antigenic relationships between LPS antigens. The serotyping system for T. hyodysenteriae which was proposed by Baum &Joens (1979) uses unabsorbed antisera and is made unworkable by these observations. Instead we propose placing organisms which share common LPS antigens into serogroups A to E, members of which are defined by their reactivity with unabsorbed sera raised against a type organism for the group. We suggest strains B78, WAI, B169, Al and WA6 respectively as being the most suitable type organisms for the five serogroups identified so far. Isolates possessing additional unique LPS antigens can be regarded as serotypes within the serogroup. However the serotype of an isolate can only be established if antiserum is prepared against it, and this serum continues to react homologously after cross-absorption with bacteria from other serotypes within the serogroup

The use of polymerase chain reaction for the identification of Serpulina hyodysenteriae

The isolation and identification of Serpulina hyodysenteriae is considered necessary to obtain a definitive diagnosis of swine dysentery (1). Identification has traditionally been carried out using phenotypic tests, although recently DNA hybridisation tests have been reported as an alternative (2). The usefulness of these and other tests relies on their ability to distinguish between S. hyodysenteriae and other spirochaetes that are frequently isolated from the porcine colon (3). Identification of pathogenic bacteria has been successfully carried out using the polymerase chain reaction ( PRC) ( 4), and in the current study this method was investigated as a means of identifying S. hyodysenteriae

Use of a whole chromosomal probe for identification of Treponema hyodysenteriae

A whole chromosomal DNA probe labelled with photobiotin was used in a dot blot hybridisation to identify DNA from isolates of Treponema hyodysenteriae, the aetiological agent of swine dysentery. The probe was evaluated using DNA from 13 isolates of T hyodysenteriae and 13 isolates of non-T hyodysenteriae spirochaetes recovered from pigs. The initial test had both a sensitivity and specificity of 92·3 per cent, although when it was repeated the specificity fell to 84·6 per cent. The test was helpful in distinguishing between T hyodysenteriae and other morphologically similar treponemes that are part of the normal flora in the large intestine of pigs. The probe could also be used to detect as little as 10 ng of purified DNA from T hyodysenteriae, or DNA from 2 × 106 bacterial cells lysed directly onto nitrocellulose

Typing of Australian isolates of Treponema hyodysenteriae by serology and by DNA restriction endonuclease analysis

A total of 91 isolates of Treponema hyodysenteriae which were obtained from 62 piggeries located around Australia were typed by serology and by DNA restriction endonuclease analysis (REA). The isolates fell into eight serogroups, of which groups B and D were the most common. Isolates with different REA patterns were recognised within serogroups, whilst a few isolates with the same REA pattern were placed into different serogroups. Some of the latter isolates were either from the same piggery or from farms with epidemiological links, thus indicating the bacteria may have altered their antigenic properties. A total of 31 different REA patterns were recognised amongst the Australian isolates. These comprised eight major patterns, with four of these being subdivided on the basis of minor differences in banding. Where a number of isolates were obtained from individual piggeries these all had the same REA pattern, and in one piggery isolates with the same pattern were recovered over a five year period. Plasmid bands were observed in 70 of the Australian isolates (77%), and in six of the seven overseas isolates included in the study for comparison. These plasmids did not affect the REA pattern. Of the States from which substantial numbers of isolates were examined, the greatest number of different strains (12 amongst 19 piggeries) were found from Victoria, and there were 10 REA patterns in strains from 24 piggeries in Queensland. Despite the large total number of different strains of T. hyodysenteriae in Australia, only three were found in more than one State