Bandwidth compression of sonar displays

A major problem affecting the design of data compression systems is that of employing a buffer of limited size and at the same time prevent uncontrollable loss of data due to overflow. One method of alleviating this problem is to employ an adaptive compression algorithm. With this design approach when overflow is imminent the compression algorithm is degraded which effectively reduces the input rate to the buffer. A method is proposed here, where by using a recirculating register as the buffer the recirculating data controls the input rate and hence the performance of the system. The system has been analysed for a Poisson input process, and simulated using synthetic patterns similar to that encountered on sonar displays. The results indicate that this form of storage is quantitatively similar to random-access storage but qualitatively superior due to the random nature of the losses. An experimental system has been built using dynamic MOS shift registers for the store and a simple run-length coding procedure

Long-term benzodiazepine and Z-drugs use in England:a survey of general practice

BackgroundCurrent British National Formulary (BNF) guidelines state that benzodiazepines and zolpidem, zopiclone, and zaleplon, commonly known as Z-drugs (BZD), be prescribed for no more than 4 weeks, although anecdotal data suggest that many patients are prescribed BZDs for much longer. As there are no recent, evidence-based estimates of long-term (&gt;12 months) BZD use in England, the scale of this potential problem is unknown.AimTo produce the first reliable, evidence-based estimate of long-term BZD use in England.Design and settingEstimates of long-term BZD use in England were projected from data obtained from a survey conducted in 2014–2015 by the Bridge Project, a prescribed-drug withdrawal support charity in the North of England (Bradford).MethodPercentages of long-term users of BZD were derived from the survey, by sampling primary care GP surgeries with around 100 000 registered patients, and these were applied to English NHS patient numbers. The data were filtered to exclude the very young and old, and those with other health issues.ResultsThe mean percentage of registered patients prescribed BZDs for more than a year in the survey sample is 0.69% (95% confidence interval [CI] = 0.54 to 0.84). Applying this value to national patient numbers yields a mean projection of 296 929 (95% CI = 232 553 to 361 305) long-term users of BZD in England. The data also suggest that as many as 119 165 of these patients may be willing to accept prescribed drug dependency withdrawal services.ConclusionMore than a quarter of a million people in England are likely to be taking highly dependency-forming hypnotic medication far beyond the recommended time scales. As there is evidence that long-term use of BZDs causes adverse physiological and neurological effects, and protracted withdrawal (with associated complications), this represents a serious public health problem.</jats:sec

The Downward Influence of Ozone Depletion in the Arctic Lower Stratosphere

Severe ozone depletion in the polar lower stratosphere has been linked to significant changes in tropospheric circulation patterns in the both hemispheres. Observed Southern Hemisphere circulation changes are easily reproduced in climate models and may be achieved by either increasing ozone depleting substances in a chemistry-climate model(CCM) or by imposing observed ozone losses as a zonally-symmetric perturbation in a prescribed-ozone global circulation model (GCM). In the Northern Hemisphere however, only the CCM method produces a circulation response in agreement with analysis of observations, while the GCM method is unable to produce any significant tropospheric circulation changes from imposing observed zonal-mean Arctic ozone losses. Confidence in a mechanistic link between Arctic stratospheric ozone change and changes in tropospheric circulation is greatly increased if the change can be reproduced using a GCM in addition to being reproducible in a CCM. This thesis demonstrates that by allowing ozone to vary along longitude, and by imposing ozone depletion during a realistic timeframe, the GCM method can produce circulation changes compatible with both the CCM method and observations. An equivalent-latitude coordinate allows the prescribed ozone field, and imposed ozone losses, to follow the polar vortex as it is systematically disturbed or displaced off the pole throughout the winter, producing a realistic circulation response in the troposphere in contrast to when ozone and its imposed losses are zonally-symmetric. Timing the imposed ozone depletion with the breakup of the polar vortex reveals that the appearance of the circulation response is very sensitive to the relative timing of these events and to the pre-existing dynamical state of the polar vortex. These results demonstrate that prescribing ozone as a zonally symmetric climatology within a GCM, as has been recent practice in the literature, is only representative of the Southern Hemisphere and is inappropriate for accurately representing processes within the Arctic stratosphere. Moreover this work demonstrates that these dynamically-evolving zonal asymmetries in ozone, which are not present in zonally-symmetric ozone schemes, play a crucial role in allowing perturbations in the Arctic stratosphere to influence the troposphere and surface conditions.Funding provided by my loving family, and the ERC ACCI Project #26776

Impairment of perceptual metacognitive accuracy and reduced prefrontal grey matter volume in first-episode psychosis

Introduction: Metacognition, or “thinking about thinking”, is a higher-order thought process that allows for the evaluation of perceptual processes for accuracy. Metacognitive accuracy is associated with the grey matter volume (GMV) in the prefrontal cortex (PFC), an area also impacted in schizophrenia. The present study set out to investigate whether deficits in metacognitive accuracy are present in the early stages of psychosis. Methods: Metacognitive accuracy in first-episode psychosis (FEP) was assessed on a perceptual decision making task and their performance compared to matched healthy control participants (N = 18). A novel signal detection theory approach was used to model metacognitive sensitivity independently from objective perceptual performance. A voxel-based morphometry investigation was also conducted on GMV. Results: We found that the FEP group demonstrated significantly worse metacognitive accuracy compared to controls (p = .039). Importantly, GMV deficits were also observed in the superior frontal gyrus. The findings suggest a specific deficit in this processing domain to exist at first episode; however, no relationship was found between GMV and metacognitive accuracy. Conclusions: Our findings support the notion that an inability to accurately scrutinise perception may underpin functional deficits observed in later schizophrenia; however, the exact neural basis of metacognitive deficits in FEP remains elusive

Where do graduates Develop their Enterprise Skills? The Value of the Contribution of Higher Education Institutions’ Context

This study investigates the value of the contribution of HEIs’ context in developing graduates enterprise skills. HEIs are under pressure to develop more enterprising graduates, particularly with the increasing numbers of graduates seeking employment and the growing dissatisfaction of employers. This study explores where graduates develop enterprise skills through investigating the impact of HE and employment contexts on their development. The paper draws on a qualitative study in the social constructionist paradigm within the pharmacy context, where interviews were conducted with pharmacy academics and employers. Results show that ability to demonstrate skills in one context does not necessarily mean ability to demonstrate them in another since the development and demonstration of enterprise skills is impacted by the contexts in which they are developed and demonstrated. The study adds value by highlighting the significant role of both HE and employment contexts in developing enterprise skills, while emphasising that these skills become more transferable through exposure to more contexts

Flow instabilities of magnetic flux tubes II. Longitudinal flow

Flow-induced instabilities are relevant for the storage and dynamics of magnetic fields in stellar convection zones and possibly also in other astrophysical contexts. We continue the study started in the first paper of this series by considering the stability properties of longitudinal flows along magnetic flux tubes. A linear stability analysis was carried out to determine criteria for the onset of instability in the framework of the approximation of thin magnetic flux tubes. In the non-dissipative case, we find Kelvin-Helmholtz instability for flow velocities exceeding a critical speed that depends on the Alfv{\'e}n speed and on the ratio of the internal and external densities. Inclusion of a friction term proportional to the relative transverse velocity leads to a friction-driven instability connected with backward (or negative energy) waves. We discuss the physical nature of this instability. In the case of a stratified external medium, the Kelvin-Helmholtz instability and the friction-driven instability can set in for flow speeds significantly lower than the Alfv{\'e}n speed. Dissipative effects can excite flow-driven instability below the thresholds for the Kelvin-Helmholtz and the undulatory (Parker-type) instabilities. This may be important for magnetic flux storage in stellar convection zones and for the stability of astrophysical jets.Comment: accepted by Astronomy & Astrophysic

Composition of continental crust altered by the emergence of land plants

Acknowledgements This paper benefited greatly from discussions with B. Keller. C.J.S., X.W. and M.S. were supported by the Natural Sciences and Environment Research Council, Discovery Grant RGPIN-2020-05639. T.R.I.M. was supported by the Natural Sciences and Environment Research Council, Undergraduate Student Research Award 551207 – 2020 with additional funding provided by L. Godin. T.M.G. and T.H. were supported by the Turing Institute under the EPSRC grant EP/N510129/1. N.S.D. and W.J.M. were supported by NERC grant NE/T00696X. G.-M.L. acknowledges support from the State Scholarship Fund of China Scholarship Council (202006410023).Peer reviewedPostprin

Preterm birth a long distance from home and its significant social and financial stress

The present paper reports a retrospective cohort of preterm infants admitted to our hospital who delivered outside the normal geographical catchment area of the mother's local level three neonatal nursery. Nineteen mothers had 21 preterm infants (23.1-34.9 weeks, 500-2330 g born) where 14 infants required ventilation (median 57 h, range 3-428). Eighteen survivors had a median length of stay of 41 days (range 3-91). Twelve of 19 mothers were interviewed: all described isolation, loneliness, poor social support and significant financial hardship related to getting their infants back to a local hospital or home. To avoid these problems, we recommend confining travel to within a short distance from home or local maternity unit after 22 weeks