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The binary X-ray source GX 1 + 4 was observed during a balloon flight in 1986, November. The source was in a relatively high intensity state. Time analysis of the data shows that the pulsation period was 111.8 ± 1.0 s indicating that one or more episodes of spin-down occurred between 1980 and 1986. Folded pulse profiles are very broad with an indication of a notch at the peak. Evidence has been found for a correlation between hard X-ray intensity and phase of the proposed 304 day orbital period. The time averaged intensity since 1980 is an order of magnitude lower than during the 1970’s. A survey of the post 1980 data shows that several reversals of the period derivative have occurred. Spin-up at the rates typical of the 1970’s has been followed by a dramatic spin-down episode with dP/dt>2.4 × 10−7 s/s.
A Skylark rocket (SL727) carrying an X-ray astronomy experiment prepared by the University of Adelaide and Tasmania (UAT) was launched from Woomera at 0030 UT on July 10, 1970. The Large Magellanic Cloud (LMC) was detected during the flight, and the recent observation of structure within the Cloud is confirmed. In particular, the data support the suggestion of X-ray emission from the 30 Doradus (Tarantula) Nebula.
Nitrification inhibitors are used in agriculture for the purpose of decreasing nitrogen (N) losses, by limiting the microbially mediated oxidation of ammonium (NH4+) to nitrate (NO3−). Successful inhibition of nitrification has been shown in numerous studies, but the extent to which inhibitors affect other N transformations in soil is largely unknown. In the present study, cattle slurry was applied to microcosms of three different grassland soils, with or without the nitrification inhibitor dicyandiamide (DCD). A solution containing NH4+ and NO3−, labelled with 15N either on the NH4+ or the NO3− part, was mixed with the slurry before application. Gross N transformation rates were estimated using a 15N tracing model. In all three soils, DCD significantly inhibited gross autotrophic nitrification, by 79–90%. Gross mineralization of recalcitrant organic N increased significantly with DCD addition in two soils, whereas gross heterotrophic nitrification from the same pool decreased with DCD addition in two soils. Fungal to bacterial ratios were not significantly affected by DCD addition. Total gross mineralization and immobilization increased significantly across the three soils when DCD was used, which suggests that DCD can cause non-target effects on soil N mineralization–immobilization turnover.
There is a clear clinical need to reliably detect residual cholesteatoma after canal wall up mastoid surgery. Ideally, this would be achieved through non-invasive radiological means rather than second-look surgery, thus preventing morbidity in those patients in whom no residual disease is found.
We describe a case in which non-echo-planar, diffusion-weighted magnetic resonance imaging sequences were used pre-operatively, and compared with subsequent surgical findings. This case highlights both the potential of this increasingly popular magnetic resonance technique and also its current limitations.
Various magnetic resonance sequencing types have been employed to try to reliably detect residual cholesteatoma, each with varying success. Non-echo-planar, fast-spin echo, diffusion-weighted sequences currently appear to be the most reliable at detecting even the smallest pearl of cholesteatoma, down to 2 mm in diameter. In our unit, a propeller, diffusion-weighted image sequence is employed on a GE Signa scanner. However, both this case study and other reports show that the accuracy of the technique is not 100 per cent. This begs the question of how much one can rely on the findings of such techniques when deciding whether second-look surgery is indicated. Scan-negative patients will require continued follow up as, at the time of imaging, residual disease may not have reached a detectable size.
Frequency-modulated sweep calls of Otomops martiensseni were recorded from individuals as they emerged from nine different building roosts near Durban, South Africa. Multiple analyses of call features, including duration (ms), lowest frequency (kHz), highest frequency (kHz) and frequency with most energy (kHz), indicated significant inter-individual variation. Discriminant function analysis of call features correctly classified the calls of individuals from four roosts > 70% on 19 of 28 times. Although other species of molossids (Chaerephon pumilus, Tadarida aegyptiaca, and one unidentified species) produced social calls as well as frequency-modulated sweep calls, O. martiensseni produced just the latter vocalizations and they were longer and lower in frequency than those of the sympatric molossids. Other species of molossids, but not O. martiensseni, produced feeding buzzes as they attacked flying insects. The frequency-modulated sweep calls of O. martiensseni seem to serve a communication function, but they may not be used in echolocation unlike similar calls by other molossids. Individually distinct communication signals (frequency-modulated sweep calls) enhance communication in a species that lives in year-round social groups (one adult male, females and dependent young).
The interest of medieval Jewish historians in the works rather than the lives of the great figures of history explains the relative paucity of biographical data to be found in their writings. Indeed the most factual contemporary accounts of the foremost Jewish thinker of the medieval period, Moses Maimonides (1135–1204), are to be found in Muslim historiographies, whereas entries of comparable substance by Jewish authors are both later in date and more fictitious in nature. Although Maimonides's legal and philosophical writings betray at times both warmth and humanity, the autobiographical letters that have come down to us, on the other hand, portray him as an extremely occupied person, whose professional engagements left him little time for the mundane affairs of his fellow men.
Four channels of EEG (T4-T6, P4-02, T3-T5, P3-01) were recorded from several groups of control subjects and schizophrenia patients on analogue tape. They were later digitized and analysed by computer; power spectra were computed for 30 second epochs of EEG per channel; eyes closed, eyes open. No difference between normal controls and neurotic in-patients was apparent. An acute schizophrenic group had less alpha power, this change being confined largely to the temporal areas. A chronic outpatient sample showed less alpha and beta power, while chronic long-stay schizophrenic patients had an excess of delta power. The changes in both chronic patient groups were diffuse rather than local.
Using a classical click/flash paradigm, the CNV was recorded from the following three groups of subjects at Broadmoor Hospital: (1) 14 ‘psychopathic’ patients selected by use of the 4/9 MMPI profile and confirmed by independent clinical diagnosis; (2) 15 ‘non psychopathic’ patients, all psychotic and mainly schizophrenic; (3) 14 healthy staff control subjects. All three groups were matched for age and sex; the two patients groups were also matched for length of stay. Two series of 32 paired stimuli were used, separated by an interval of 30 minutes. The mean CNV voltage was significantly lower in the ‘non-psychopathic’ patients. The amplitude of the ‘psychopath's' CNV response did not differ significantly from that of the staff controls, but the response variability between the first and second series of trials was much greater in the ‘psychopathic’ patients than in the other two subject groups. The ‘psychopathic’ subjects tended to show more rapid initial development of the CNV.
A sample of borstal boys was selected (56). All had an assessment of mental state and ratings of sociopathy and aggressiveness performed, using structured interview techniques. A group of RAMC apprentices matched for age, sex and social class, was also examined (56). Eight-channel bipolar scalp EEG recordings were taken, 4 channels (T4–T6, P4–O2, T3–T5, P3–O1) being recorded on analogue tape. The tape-recorded signals were filtered off line through a low pass filter, multiplexed and digitized on to magnetic tape. Power spectral analysis was carried out on this data, using the University of London CDC 60 600 computer. Three 30-second epochs were analysed: eyes closed, eyes open, and eyes closed. No significant EEG differences were found between the borstal boys and the control sample. Neither visual inspection nor power spectral analysis revealed any EEG differences between the borstal boys and controls. Correlation coefficients between the power at each frequency from all four channels, the violence and sociopathy ratings and the time spent in institutional care in months for each boy were computed. These showed that violence contributes not more than 1 per cent and sociopathy not more than 5 per cent to the variance of the EEG power. Duration of stay in the institution accounted for as much as 20 per cent of the variance of the EEG power with significant correlations at 7 Hz (positive) and 11 Hz (negative). Duration of stay is thus a variable that must be controlled for during the investigation of subjects in penal institutions and long-stay hospitals.
This report is concerned with a simple statistical model of the way the brain may function, suggested by the analysis of intelligence test results in two groups of children. The model describes the statistical behaviour of an ideal array of elements, representing the brain, during tests of cognitive ability. Predictions from the model indicate that comparison of the EEC recording taken from groups of children who were good or poor readers would show amplitude differences. These were found between the groups when the eyes were open but not when the eyes were closed–a result explained by the model.
Two samples of Special Hospital patients who had posterior temporal slow wave foci were selected and matched for age, sex, and duration of stay with patients from the same hospital who had normal EEG records. A high prevalence of between 20 and 31% was found. No significant differences were found between the index and control groups with regard to a number of developmental, forensic, psychiatric, behavioural, and psychometric variables. A striking feature was the high average age of almost 30 years of the posterior temporal slow wave patients. This finding suggests that the current maturation defect hypothesis in relation to cerebral function in psychopaths requires revision. The possible role of early social and environmental factors in the genesis of these EEG anomalies is discussed.