Showing papers by "Suffolk University published in 1991"

A uniform decimal code for growth stages of crops and weeds

Abstract: Summary A universal scale (to be known as the BBCH scale) using a decimal code for the description of the growth stages of most agricultural crops and weeds is proposed. The scale and codes are based on the well-known Zadoks code for cereals. Developmentally similar growth stages of different crops are given the same codes. The general scale provides a framework within which more specific scales for individual crops may be constructed. The uniformity of the scale makes it easy to remember and use in agricultural practice and simplifies storage and retrieval in a computer system. A description of the general scale is given followed by specific scales for cereals, rice, maize, oilseed rape, field beans, peas and sunflower. Comparisons with scales currently in use are given where appropriate.

The effect of age and parity on the development of equine chronic endometrial disease

Abstract: The results of a retrospective analysis of 3,804 endometrial biopsy specimens collected from non-pregnant mares during the course of routine equine stud farm practice demonstrates a significant and practically useful correlation between the severity of chronic degenerative endometrial disease (CDE) diagnosed and age of mare at the time of examination. There were significant correlations between the number of foals born and the mares' barren years prior to biopsy and the severity of CDE, but the differences were not sufficiently large to be useful. Correlations between the severity of chronic infiltrative endometritis (CIE) and age or pre-biopsy parity were minimal. The results suggest that using similar histopathological criteria to those used by Kenney and Doig (1986), mares up to nine years of age should have no signs of CDE, mares up to 13 years of age should have no more than mild signs, mares up to 15 years of age should have no more than moderate signs and mares aged 17 years or older are likely to have severe signs. We believe that these guidelines are a useful, objective aid for formulating a breeding prognosis.

The prevalence of enteric pathogens in diarrhoeic Thoroughbred foals in Britain and Ireland

Abstract: Summary A survey of 77 normal and 326 diarrhoeic foals in Britain and Ireland from 1987 to 1989 revealed a significantly higher prevalence of Group A rotaviruses and Aeromonas hydrophila in diarrhoeic foals. The prevalence of cryptosporidia, potentially pathogenic Escherichia coli, Yersinia enterocolitica and Clostridium perfringens was similar in normal or diarrhoeic foals. Rotaviruses had a similar prevalence in all age groups of scouring foals up to three months of age, with an overall prevalence of 37 per cent among diarrhoeic foals. The number of cases of diarrhoea varied considerably from year to year, but in all three years of the survey rotavirus was a significant pathogen. A comparison of diagnostic tests for rotavirus in the faeces showed electron microscopy (EM) and polyacrylamide gel electrophoresis (PAGE) to have similar sensitivity. The Rotazyme ELISA test kit was found to have the same sensitivity as a combination of EM and PAGE. A. hydrophila had an overall prevalence of 9 per cent among diarrhoeic foals, although its prevalence was higher in some age groups. A. hydrophila has not been established previously as a significant enteric pathogen in foals. Other putative pathogens found at very low prevalence were coronavirus, the putative picobirnavirus, Campylobacter spp. and Salmonella spp. No evidence was found of synergistic effects between rotavirus, cryptosporidia and potentially pathogenic E. coli. Neither coccidia nor non-Group A rotaviruses were found in any of the samples examined.

Effects of placental pathology on maternal plasma progestagen and mammary secretion calcium concentrations and on neonatal adrenocortical function in the horse.

Abstract: Between 1985 and 1990, 25 Thoroughbred mares were classified as having an abnormal pregnancy on the basis of precocious signs of impending parturition. Throughout the remainder of their pregnancies, plasma progestagen and mammary secretion calcium concentrations were monitored. After parturition, evidence of placental pathology was recorded and their foals were assessed with regard to adrenocortical function and behaviour. Seven pony mares were used to establish a model of placental pathology and, following induced placental separation, were subjected to the same protocol. Control animals consisted of 35 Thoroughbred mares and 39 pony mares, all considered to have normal pregnancies. Of the 25 abnormal mares, 16 had precociously increased plasma progestagen concentrations, 17 had precociously increased mammary calcium concentrations and 24 had an abnormal placenta. Eighteen live foals resulted, of which 11 appeared abnormal on the basis of behaviour. Adrenocortical function was assessed in 13; 4 had normo- and 3 hypofunction and 6 were intermediate. These results were independent of gestational age at delivery. Of 13 foals examined for plasma progestagens, 7 had normal and 6 abnormal concentrations. Following placental separation in the pony mares, maternal plasma progestagen concentrations increased in 4 of the 7 mares within 4-11 days and in 1 after 42 days; there was placental pathology in 3 of these mares, 1 of which aborted at 287 days gestation. There was no increment in progestagens in the remaining 2 mares, which aborted at 240 days and 271 days. It was concluded that placental dysfunction may be diagnosed from early plasma progestagen increments prior to 308 days gestation; and that foals that survive birth in these circumstances may be physiologically immature but often have normal or intermediate adrenocortical function, irrespective of gestational age. This is in contrast to foals born prematurely without maternal plasma progestagen or mammary secretion calcium increments.

The dentition of red deer (Cervus elaphus): a scoring scheme to assess age from wear of the permanent molariform teeth

Abstract: Skulls of red deer (Cervus elaphus of known age were examined. A scoring procedure devised for fallow deer (Dama dama) was used to relate tooth wear to a particular age (Brown & Chapman, 1990). The precise sequential nature of tooth wear as it appeared on the slopes and tips of cusps, on the marginal ridges and links between cusps was recorded. From these data a base has been provided from which estimates of age may be made of animals of unknown age. The variability for the scores are given for 95% prediction intervals from the regression of age on total molar wear score.

Adaptation to divorce and ego development in adult women.

Abstract: The purpose of this study was to assess how the experience of stressful life changes might provide an opportunity for ego development in adulthood. The sample included 104 women in the early stage of the separation and divorce process; 91% of the sample was recontacted after 1 year had elapsed. Longitudinal analyses of the adaptation process supported the hypothesis that marital separation and divorce might be a disequilibrating life change, but one that might foster ego development. Those women who experienced this life change as disequilibrating but who made a successful adaptation by Time 2 showed a significant increase in ego level. Furthermore, those women who were high in adjustment at Time 1 but low in adjustment at Time 2 showed a theoretically consistent regression in ego level. Patterns of adaptation to life changes, their relationship to ego development, and the theoretical implications for Loevinger's model are discussed.

Age assessment of red deer (Cervus elaphus): from a scoring scheme based on radiographs of developing permanent molariform teeth

Abstract: The stages of permanent tooth development observed in radiographs of the mandible are described and analysed for known-aged red deer (Cervus elaphus} The ages by which the different stages of development were reached have been determined By allocating scores for these different stages, the scores that may be expected for a particular age have been identified Lastly, the predicted age was given, together with 95% prediction intervals obtained from a regression of age on total molariform scores Tooth development in red deer was usually completed by 33 months These data can be used to assess the ages of animals of unknown age

An investigation of industry and firm structural characteristics in corporate turnarounds

Abstract: This article uses the structure/conduct/performance framework as an underpinning to investigate the attributes of turnaround firms. Turnaround is defined as a substantial improvement of the firms's return on assets relative to the average return of its industry. Industry and firm structural characteristics including concentration, industry growth, R&D, advertising, market share, size, diversification, capital intensity and margins are identified. The results of a series of univariate and multivariate tests run on a sample of turnaround and non-turnaround firms indicate that size, R&D, and an interaction between operating margin and advertising can be helpful in explaining some turnaround situations.

Collection and display device

Abstract: The present invention relates to a device for assessing a fluid sample, characterised in that it comprises: a) a fluid receptor means adapted to receive a sample of a fluid from an external source; b) a substantially closed chamber adapted to receive fluid from the receptor means by means of fluid flow connection therebetween, the chamber having at least part of a wall thereof provided by a member carrying one or more reagents adapted to respond to one or more components of the fluid sample and adapted to give an indication of that response which can be detected from the exterior of the chamber. The invention also provides a method for assessing a fluid sample in which the sample is placed in the receptor of a device of the invention and allowed to contact the reagent(s) within the chamber to provide a colour or other reaction which can be detected externally through the wall of the chamber.

Dynamics of competition between wild oats (Avena fatua L.) and winter cereals

Abstract: Summary: This study examined the effects of competition on the growth of Avena fatua, winter wheat and winter barley. Plants were sampled at frequent intervals from replacement series experiments at two contrasting sites in the U.K. A. fatua was much slower to establish than the two cereals, but thereafter exhibited a faster rate of growth. In monoculture, it took a considerable time for A. fatua to reach a size equal to that of the cereals, but by the end of the experiments it was the largest of the three species. The change-over from cereal dominance in mixtures to A. fatua tiominance was rapid, and in three cases coincided with cereal flag leaf emergence. In the fourth case, it appeared to coincide with the art of canopy height extension. At one site the rder of competitiveness at anthesis was A. fatua= barley>wheat, and at the other site the order was A. fatua>wheat>barley. In order to explain and predict differences between years and sites, more studies are required on morphological development in relation to abiotic variables. Resume: Cette etude examine les effets de la competition entre les croissances d'Avena fatua, des orges et des bles d'hiver. Les plantes ont eteechantillonnees a intervalles frequents a partir d'experimentation en series de remplacement dans deux sites contrastes du Royaume-Uni. Avena fatua s'etablit beaucoup plus lentement que les deux cereales, mais par la suite a un taux de croissance plus rapide. En monoculture, il faut un temps important pour qu'A. fatua atteigne une taille egale a celles des cereales, mais a la fin des experimentations, c'etait la plus grande des 3 especes. Le changement de dominance des cereales en melange avec d'A. fatua est rapide et coincide dans les 3 cas a la sortie de la derniere feuille. Dans l'autre cas, il a coincide au depart de Textension de la hauteur de la canopee. Sur un site, l'ordre de competitivitea l'anthese etait: A. fatua= orge>ble, et sur l'autre A. fatua>ble>orge. En vue d'expliquer et de prevoir les differences entre les annees et les lieux, un travail supplementaire est necessaire sur le developpement morphologique en relation avec des variables abiotiques. Zusammenfassung: Es wurde die Wirkung der Konkurrenz auf das Wachstum von Avena fatua, Winterweizen und Wintergerste untersucht. Die Pflanzenproben wurden zu verschiedenen Zeitpunkten aus sub-stitutiven Versuchen an 2 gegensatzlichen Orten im Vereinigten Konigreich gezogen. Avena fatua etablierte sich viel langsamer als die beiden Getreidearten, aber spater hatte das Unkraut eine grosere Wachstumsrate. In Reinkultur erreichte Avena fatua die gleiche Grose wie die Getreide erst nach einiger Zeit, doch am Versuchsende war die Art die groste von allen drei. Der Ubergang von der Getreidedominanz in Mischungen zur Avena-fatua-Dominanz war schnell und fiel in 3 Fallen mit dem Erscheinen des Fahnenblatts zusammen. Im anderen Fall schien er mit dem Bestandesschlus zusammenzufallen. Zur Zeit der Blute war das Konkurrenzverhaltnis an dem einen Ort Avena fatua= Wintergerste > Winterweizen, am anderen Avena fatua > Winterweizen > Wintergerste. Fur die Interpretation und die Prognose von Unterschieden zwischen den verschiedenen Jahren und Orten sind weitere Untersuchungen uber die morphologische Entwicklung in Abhangigkeit von abiotischen Faktoren erforderlich.

Assessment of the breeding prognosis of mares using paired endometrial biopsy techniques

Abstract: Paired endometrial biopsy samples were taken from 530 subfertile mares, before and after treatment (where indicated) and a period of sexual rest Prognoses were made after each biopsy (Categories 1A-4A before treatment and Categories 1B-4B after treatment), using histopathological criteria similar to those described by Kenney and Doig (1986) Eighty-seven per cent of the mares were assigned to first biopsy prognosis Category 3A The second biopsy prognosis produced a more even population distribution (10, 47, 40 and 3 per cent respectively for Category 1B, 2B, 3B and 4B mares) First biopsy Category 3A and 4A mares produced mean foaling rates of 51 and 40 per cent respectively None of the 14 second biopsy Category 4B mares delivered a live foal (12 were barren, one aborted and one suffered early foetal death) This study supports the hypothesis that a breeding prognosis assigned on the basis of two endometrial biopsy samples, taken before and after specific uterine treatment, where indicated, which takes into consideration the mare's ability to respond to treatment, is likely to be more accurate than one assigned after a single biopsy sample

The relationships between career concerns and political tactics in organizations

Abstract: Summary The study examined the relationships between four career concerns (Personal Success, Organizational Involvement, Skill Development and Autonomy) and two categories of political tactics in organizations (Hierarchical Tactics and Networking Tactics) in a sample of management school alumni. Career concerns were not related to the employment of hierarchical tactics but were strongly related to the use of networking tactics. 'External' career concerns of personal success and organizational involvement were more strongly related to political behavior than 'internal' career concerns of skill development and autonomy. Organization size was significantly related to the use of hierarchical tactics but not to the use of networking tactics. Type of organization structure (mechanistic versus organic) did not have a direct effect on political behavior but moderated the relationships between career concerns and political tactics. These relationships were stronger in organic than in mechanistic organizations.

Plasma progestagen concentrations in the normal and dysmature newborn foal.

Abstract: Radioimmunoassay (RIA) and gas chromatography-mass spectrometry (GC-MS) were used to determine plasma progestagen concentrations in the normal and premature foal. Radioimmunoassay provides a profile of plasma progestagens with respect to time but, due to the non-specific nature of the technique and without prior chromatographic purification, quantitative data based on RIA analysis must be interpreted with caution. In contrast, the greater specificity of GC-MS allows identification of specific plasma progestagens and measuring of multiple analytes in a single analysis. Both techniques demonstrated a marked difference in plasma progestagen concentrations between the normal and abnormal foal. GC-MS studies demonstrated that the plasma steroid profile was dominated by pregnenolone and 5-pregnene-3 beta, 20 beta-diol. Measuring the amounts of these 2 steroids in a single analysis demonstrated persistent high concentrations in premature foals, whereas concentrations decreased rapidly in the first few hours following birth in the normal foal. Preliminary analyses of urinary concentrations in the 2 steroids demonstrated again differences between normal and abnormal foals.

Failure of passive transfer of colostral immunity in the foal: incidence, and the effect of stud management and plasma transfusions

Abstract: The importance of colostrum for the passive transfer of maternal immunity to foals is well recognised. This survey reports the incidence of the failure of passive transfer of colostral immunity in thoroughbred foals in the United Kingdom during 1988 to 1990, and the effect of plasma transfusions on IgG levels in a group of them. The incidence of disease in these foals first month of life is also recorded.

Race and Politics in Britain

Abstract: Thinking about race in British politics beyond the colourblindness of political studies. Part 1 The historical context: British history, black people and British capitalism the British Raj and aftermath the Victorians and scientific racism the other white minorities early 20th- century attitudes towards race early black political activism. Part 2 The social-demography of multi-racial Britain: size and location of black Britons patterns of immigration geographic distribution age and gender jobs and housing. Part 3 Problems of a multi-racial society: the rising political saliency of immigration, 1945-1962 building the new liberal consensus. Part 4 Race and party politics: industrial recovery and labour shortages, 1948-1976 the populist ticket, 1976-1983 one-nation Toryism versus radical race politics, 1983-1991. Part 5 Black political participation: ethnic votes and voting - definition and interpretation black voting patterns a profile of black electoral behaviour the routes to representation. Part 6 The politics of race, nation and culture: the Powell legacy the rise and fall of the extreme right the New Right agenda. Part 7 Concluding remarks: the political analysis of race liberals and their critics future prospects.

Infection of sugar beet by Polymyxa betae in relation to soil temperature

Abstract: The effects of soil temperature on infection of sugar-beet roots by the soil-borne fungus Polymyxa betae were investigated in controlled environments. Pre-germinated seeds were sown in pots of naturally infested soil and seedlings sampled at frequent intervals over a period of several weeks. Within the range 10-30-degrees-C, the optimum soil temperature for infection was c. 25-degrees-C; the time between sowing and the first detectable infection was shortest and the subsequent rate of infection most rapid at this temperature. No infection was observed over 80 days at 10-degrees-C. Both root and shoot dry weight were reduced on plants growing in infested soil at 15, 20 and 25-degrees-C compared with those growing in uninfested soil. In general, root growth was more severely affected than shoot growth and the effects were most pronounced at 20-degrees-C. These results were confirmed in a subsequent experiment in which P. betae-infected root material was used as the inoculum. In addition to its role as the vector of beet necrotic yellow vein virus (the cause of Rhizomania disease), the significance of P. betae as a plant pathogen in its own right is discussed.

The development of a gas chromatographic/mass spectrometric screening procedure to detect the administration of anabolic steroids to the horse.

Abstract: A screening procedure for anabolic steroid residues in horse urine has been developed based upon solid-phase extraction and gas chromatographic/mass spectrometric analysis in the selected ion mode. For moderate sample throughput the method provides a viable alternative to radioimmunoassay screening and has advantages over the latter technique due to its flexibility, specificity and ability to detect a number of steroids in a single analysis. Full automation of the gas chromatographic/mass spectrometric analysis is an additional feature of the methodology.

Simulated stair climbing exercise apparatus having variable sensory feedback

Abstract: A simulated stair climbing exercise apparatus having variable sensory feedback is provided. Sensory feedback, in the form of a lifting force acting on a lifting foot of the operator, varies with the operator's location in the stepping stroke. Maximum sensory feedback is provided at a lower portion of the stroke, minimum sensory feedback is provided at an upper portion of the stroke and maximum feedback at the lower portions. Sensory feedback is effected by means of direct interconnection of left and right foot mechanisms in combination with a spring. Direct interconnection is achieved by a cable routed around a series of pulleys such that a downward force on one foot mechanism results in an equal and opposite lifting force on the other foot mechanism. One of the pulleys is a floating pulley that is free to move and its positioned based upon the operating position of the stepping stroke. The spring is connected to the floating pulley such at 1) the direct interconnection cable controls the lifting force in the lower portion of the stroke, 2) the spring controls the lifting force at the upper portion of the stroke, and 3) a combination of the cable and spring control lifting force in the mid range.

Spontaneous pneumothorax: marker gas technique for predicting outcome of manual aspiration.

Abstract: OBJECTIVE--To determine whether in a patient with spontaneous pneumothorax the presence or absence of a pleural leak can be shown at the time of manual aspiration by use of a marker gas. Also, to find out if the technique can predict whether manual aspiration will be successful, hence avoiding the need for intercostal tube drainage. DESIGN--Prospective study of 25 episodes of pneumothorax during which patients breathed air from a Douglas bag that contained chlorofluorocarbon gases from a metered dose inhaler while the pneumothorax was aspirated. SETTING--Medical unit of a district general hospital. PATIENTS--22 patients who presented over nine months with acute pneumothorax. MAIN OUTCOME MEASURES--Presence or absence of chlorofluorocarbon marker gases in the aspirate. Presence or absence of sustained re-expansion of the affected lung in the chest radiograph. RESULTS--Marker gas was detected in the aspirate from 16 out of 25 pneumothoraces. Of these, 13 required intercostal tube drainage because of failure of the lung to re-expand. Marker gas was not detected in nine cases, and in all of these cases manual aspiration resulted in sustained re-expansion of the lung. CONCLUSIONS--The presence or absence of a pleural leak during manual aspiration of spontaneous pneumothorax can be shown by using this technique. The absence of marker gas in the aspirate implies that manual aspiration will be successful, whereas its presence predicts, in most cases, either failure of manual aspiration to expand the lung or early re-collapse of the lung.

Age assessment of fallow deer (Dama dama): from a scoring scheme based on radiographs of developing permanent molariform teeth

Abstract: The stages of permanent tooth development observed in radiographs of the mandible were described for known-aged fallow deer Dama dama. Ten stages were defined and, by allocating scores for these stages, the scores that may be expected for a particular age have been identified. Lastly, the predicted age was given for total molariform scores. These were obtained, with 95% prediction intervals, from a regression of age on total molariform scores. An age assessment from tooth development stages can be made up to three years, after which, no further development takes place.

Expression of major histocompatibility complex (MHC) class 1 molecules on early trophoblast.

Abstract: The expression of class I Major Histocompatibility Complex (MHC) molecules by early trophoblast of intraspecific horse and donkey, interspecific mule and extraspecific donkey-in-horse conceptuses was determined using a rat monoclonal antibody (MAC 291) in a peroxidase anti-peroxidase immunohistochemical technique. Most non-invasive allantochorion of horse, donkey and mule conceptuses did not express class I MHC molecules at any stage of gestation except in small isolated patches of pseudostratified trophoblast lying adjacent to the openings of endometrial glands. In contrast, MHC class I molecules were expressed strongly on horse chorionic girdle cells at Days 33 and 34 of gestation, just prior to their invasion. However, class I MHC was down-regulated with the differentiation of these girdle cells into mature gonadotrophin-secreting endometrial cup cells between Days 40 and 45 so that by Days 55-65, class I molecules were no longer detected on endometrial cups. Similarly, all endometrial cups originating from 3 intraspecific donkey conceptuses at Days 41, 59 and 82 and 2 interspecific mule conceptuses at Days 46 and 47 were negative for class I molecules. A total of 7 extraspecific donkey-in-horse pregnancies, in which no endometrial cups from and implantation is abnormal, were established by embryo transfer. The chorionic girdle recovered from a single donkey-in-horse conceptus at Day 35 of gestation stained strongly for MHC class I molecules. Later in gestation (Days 73-91) and in contrast to the other forms of equine pregnancy examined, most unimplanted, failing donkey allantochorion was strongly stained for MHC class I molecules and had large numbers of lymphocytes in the adjacent endometrial stroma. The hypothesis is raised that the mechanisms that normally suppress the expression of MHC class I molecules by the epithelial trophoblast layer of the equine placenta can only function if the apical surface of the cells is in close and stable contact with other tissues such as the endometrial epithelium.

Does Interpretive Test Score Information Help Teachers

Abstract: To what extent do teachers possess the competence to interpret state testing program results properly?

Metabolic changes in thoroughbred and pony foals during the first 24 h post partum.

Abstract: Metabolic rates, rectal temperatures and respiratory quotients (RQ) were determined during the first 24 h post partum in Thoroughbred and pony foals and in relation to environmental temperature. Both breeds had high metabolic rates (greater than 200 W/m2) during the first hour post partum when they were wet and shivering; by 4 to 24 h values were fairly steady at about 153 and 105 W/m2 for Thoroughbred and pony foals, respectively. At birth, rectal temperature was lower in Thoroughbred foals than in pony foals; values increased during the first hour, and then decreased. At 24 h of age, both breeds had a rectal temperature of 38.4 degrees C. RQ values were high (greater than 0.9) at birth in both breeds, declining to about 0.82 by 4 to 24 h of age. At similar environmental temperatures, the metabolic rates per unit area of Thoroughbred foals were higher than those of pony foals at all ages. The results indicate that breed differences may exist between the thermal responses of newborn Thoroughbred and pony foals.

Assisted ventilation. 5. Non-invasive and domiciliary ventilation: negative pressure techniques.

Abstract: Historical development Negative pressure ventilation first came into use during the second half of the nineteenth century. It was recognised that air would be drawn into the lungs through the mouth and nose if a subatmospheric pressure could be developed around the thorax and abdomen. When the pressure around the -chest wall returned to that of the ambient air, expiration occurred passively owing to the elastic recoil of the lungs and chest wall. The chest and abdomen are enclosed in an airtight, rigid chamber in all types of negative pressure ventilator, but in most of the earlier designs the whole of the body up to the neck was also contained in the chamber. This had the advantage that chest wall expansion was not limited by contact with the sides of the negative pressure device and that only one airtight seal, that around the neck, was required. The first of these negative pressure ventilators to be of clinical value was that developed at Harvard University Medical School by Drinker, an engineer, in 1928.1 He designed severaI modified versions of his tank ventilatof or irohlung and-these were widely used during the poliomyelitis epidemics of the next 30 years. Tank ventilators were produced that could be constructed rapidly when needed and small enough for children.2 Most of the early designs were telescopic in that the patient was pulled in and out of the main chamber of the tank on the mattress. In the later designs the upper part of the chamber was hinged towards the foot end and opened upwards (alligator type). Simpler, non-tank negative pressure ventilators were first developed around the end of the nineteenth century. The most successful of these was Eisenmenger's biomotor, a cuirass designed in 1904.' This was superseded by various negative pressure shells or cuirasses introduced from 1930 to 1960. These were not as effective as the tank ventilators or the modern individually moulded cuirasses, but because of their simplicity they became widely used, particularly during recovery from acute poliomyelitis. In the 1950s the jacket (wrap or poncho) design of negative pressure ventilator was produced,4 in which the properties of rigidity and imperviousness to air were separated into two structures. The rigidity was provided by an inner framework of metal or plastic and this was covered by an airtight anorak like garment with seals around the neck, arms, and usually the waist. The jacket, like the tank and cuirass, was connected to a pump, which generated a negative pressure between it and the patient's chest wall. All these types of negative pressure ventilator were used both in hospital and at home to treat acute and chronic ventilatory failure. Ironically, as substantial improvements in their design were being made intermittent positive pressure ventilation using a translaryngeal endotracheal tube or a tracheostomy was shown to be more successful in the poliomyelitis epidemics, such as that in Copenhagen in 1952.' The superiority of intermittent positive pressure ventilation was balbly to better protection of tie airway rom asp ti gaNive pressure ventilators rapidly fell out of favour. In the last decade, however, negative pressure techniques have been used once again for various conditions, particularly neuromuscular and skeletal disorders, and have been shown to have a place, particularly for long term nocturnal ventilation in the home.6