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Retail live poultry markets (LPMs) may act as a reservoir of avian influenza viruses (AIV). In this study we test the hypothesis that a rest day in the LPMs where the stalls are completely emptied of poultry, cleansed, and restocked will reduce the isolation rates of avian influenza viruses. The isolation rate of H9N2 subtype viruses from chicken was significantly lower after the rest day than prior to it, indicating its impact in reducing transmission. In contrast, Newcastle disease virus (NDV) isolation rates appear unaffected by this intervention, possibly reflecting differences in herd immunity or virus transmission dynamics.

The dynamic behaviour of water droplets subject to AC electric fields is investigated by experiment and finite element modelling. The motion of a water droplet is considered on the surface of a metallic sphere. To understand the consequences of vibration, the FEA model is introduced to study the dynamics of a single droplet in terms of phase shift between vibration and exciting voltage. Moreover, the evolution of electric field within the whole cycle of vibration is investigated. The finite element treatment to couple the electromagnetic field with multi-phase flow field is described. The profile of the electric field and the characteristics of mechanical vibration are evaluated. Surprisingly the phase shift in these characteristics results in the maximum field occurring when the droplet is in a flattened profile rather than when it is ‘pointed’.

The surface potential gradient is a critical design parameter for planning overhead lines, as it determines the level of corona loss (CL), radio interference (RI), and audible noise (AN). The majority of existing models for surface gradient calculation are based on analytical methods which restrict their application in simulating complex surface geometry. This article proposes a novel method which utilizes both analytical and numerical procedures to predict the surface gradient. One of UK National Grid's transmission line configurations has been selected as an example to compare the results for different methods. The different stranding shapes are a key variable in determining dry surface fields.

The investigations were carried out in the Inland Savanna Forest Zone of the Northern Territories of the Gold Coast, the climate of which is characterised by extreme variations in rainfall and relative humidity between the wet and dry seasons.Glossina palpalis and G. tachinoides are widely distributed along the waterways throughout the zone. They come into intimate contact with the human population and are, in consequence, the most important vectors of human and animal trypanosomiasis.G. morsitans submorsitans occupies unpopulated and thinly populated regions and so, coming more rarely into contact with man and cattle, is a less important vector of trypanosomiasis.A pandemic of sleeping sickness, with 30,000 square miles of heavily infected country, lies across the upper reaches of the Volta rivers and involves parts of the north of the Gold Coast. In the areas studied high rates of infection (4–7 per cent.) were found associated with serious population declines which have given rise to secondary evils, the invasion of G. morsitans into depopulated parts and the concentration of populations on the watersheds between infected river valleys, with resultant over-farming, erosion and lowering of the standard of living.The results of two methods of controlling G. palpalis and G. tachinoides were studied : (1) “ Protective Clearings ”, aimed at breaking the contact between the tsetse and man or cattle at certain points only ; (2) “ Eradicative Clearing ”, aimed at the complete removal of tsetse throughout an area.The effects of protective clearings on the fly were as follows : Clearings less than 300 yards in length are considered useless, and may cause an increase in fly-incidence by forming artificial feeding grounds. Clearings of 440 yards can effect up to 70 per cent, reduction in fly-incidence measured over a long period, but for several months of the year show no reduction or may even show an increased incidence. Clearings up to 880 yards long can bring about 60–90 per cent, fly reduction, but at two periods during the year, at the end of the dry season and in the middle of the rains, their effectiveness is considerably lowered by the invasion of hungry flies into the clearings. Clearings over a mile in length exclude all but a few vagrant flies, but even five miles of clearing are traversed by occasional flies.A study of the effects of various applications of protective clearings on the incidence of sleeping sickness led to the following conclusions. To have any value protective clearings must be made in as many places as possible over a wide area. They effect no general reduction in the disease if applied at a few places only. Small clearings, averaging 400 yards in length, if made consistently over a large area, can effect up to 40 per cent, reduction in sleeping sickness in 4–5 years, after which the disease tends to become stabilised at the lower level. Long clearings, averaging 1,000 yards, almost double the rate and amount of reduction, effecting 70 per cent, reduction in three years, but the tendency for the disease eventually to become stabilised remains. Clearings over a mile in length at each village caused a reduction of 85 per cent, in one area.Protective clearings alone are considered unlikely to be able to effect complete control in areas of serious endemic sleeping sickness. They do not entirely exclude the fly, and they do not touch all the points where the transmission of infection takes place. Further disadvantages arise from the fact that, to attain maximum fly reduction, all vegetation, including tall trees, should be cut. This is expensive and difficult and may lead to erosion and the silting up of water-holes, thus driving the people back to uncleared parts of the river. Finally, animal trypanosomiasis can never be controlled by localised clearings, therefore improvement in animal husbandry, and consequently in agricultural practice and nutrition cannot be fully realised.Eradication of G. palpalis and G. tachinoides is based on the consideration of the tsetse community of a complete river system as a natural biological unit. During the prevalence of the adverse climatic conditions of the dry season, the breeding and survival of tsetses are possible only in certain restricted habitats from which the flies spread extensively along the water courses during the rains. The dry-season habitats are confined to definite plant associations that are characterised by a limited number of species of trees and shrubs. The removal of only these species throughout a river system renders the habitats untenable during 4–6 months of the dry season and results in the disappearance of the whole fly community.By the method of selective clearing, 1,050 square miles of country in the northwest corner of the Gold Coast were freed from tsetse between December, 1940 and March, 1945. On the main river of this region, the Kamba, which was cleared by 1942, routine catching after clearing showed 1–8 flies per year in places where the pre-clearing averages had been 2,700–7,500 flies per year. After the clearing of some neighbouring fly-belts, these occasional captures ceased. Wet-season migration from the uncleared Volta, however, brings small numbers of flies 5–9 miles up the lower reaches of the cleared river.The incidence of sleeping sickness for the Kamba area fell by 92 per cent, between 1938, the year before the start of control measures, and 1944.Along the Kamba, 160 square miles of land which had become depopulated through trypanosomiasis is being developed voluntarily by the natives, by farming, grazing, etc. Approximately 1,000 people have settled in parts of this area since clearing was finished.In 1939 G. morsitans invaded the depopulated area, and increased greatly in numbers in the following years. The spread was checked, and finally a high degree of control was established by the disturbance of big game and its reduction in numbers. Settlement of the thinly populated country is needed to consolidate this control.Selective clearing can be followed by the eradication of essential dry-season habitat vegetation which will enable maintenance to be put on a long-term rotation of about ten years. Permanent reclamation is a possibility that is now being studied.The relative merits of medical and entomological methods of controlling sleeping sickness are discussed. Mass treatment can have great success, but fails to control under difficult conditions, and has not yet been found able to eliminate the disease. The addition of adequate tsetse control increases the effect of mass treatment. Eradication of the fly is capable of eliminating the disease and does not require the addition of mass treatment to bring this about.The removal of tsetse throughout the river system, as in selective clearing, has the following additional advantages : It makes possible a sound agricultural development based on the possession of good quality livestock; this reflects also on nutrition. It enables the population to live with impunity in the vicinity of permanent water and, by spreading out at a density optimum for their type of agriculture, to avoid concentrations at local clearings or on dry, hilly country away from rivers; thus the possibilities of over-farming and erosion are avoided and the watersheds and headwaters can be reserved for afforestation. By these means, instead of ground being abandoned to the tsetse, the fly is replaced by a healthy agricultural population.

A study was conducted to investigate the persistence of rabbit haemorrhagic disease virus (RHDV) in the environment. Virus was impregnated onto two carrier materials (cotton tape and bovine liver) and exposed to environmental conditions on pasture during autumn in New Zealand. Samples were collected after 1, 10, 44 and 91 days and the viability of the virus was determined by oral inoculation of susceptible 11- to 14-week-old New Zealand White rabbits. Evidence of RHDV infection was based on clinical and pathological signs and/or seroconversion to RHDV. Virus impregnated on cotton tape was viable at 10 days of exposure but not at 44 days, while in bovine liver it was still viable at 91 days. The results of this study suggest that RHDV in animal tissues such as rabbit carcasses can survive for at least 3 months in the field, while virus exposed directly to environmental conditions, such as dried excreted virus, is viable for a period of less than 1 month. Survival of RHDV in the tissues of dead animals could, therefore, provide a persistent reservoir of virus, which could initiate new outbreaks of disease after extended delays.

Recent experience with foot and mouth disease (FMD) has shown that large and very costly epidemics can occur in countries considered extremely unlikely to experience the disease. The consequences of an introduction are much more severe than in the past and effective control is more difficult to achieve. Few countries have developed effective risk management strategies and information-based response systems to respond to these developments. The authors describe the tools which can be employed to minimise the impact of a disease incursion, using the example of FMD. To make such systems effective, the development of a national farms database in advance, including geo-referencing, is highly desirable. This greatly enhances the power of the decision-support tools, which can then be applied as soon as a serious disease incursion has been detected. These tools include procedures to detect infected farms promptly, to protect as yet uninfected farms against exposure to virus and to manage control policies. Epidemiological evaluation and prediction tools have advanced particularly rapidly and can guide the choice of control policies during an outbreak. Integrated decision-support systems offer the best method of managing FMD outbreaks to minimise the cost and size of the epidemics.

Novel carbon materials with nanometer dimensions are of potentially significant importance for a number of advanced technological applications. Currently, considerable interest exists in the possible applications of single wall carbon nanotubes (SWNTs) to proton exchange membrane (PEM) fuel cells. Proposed uses include as anode materials in both hydrogen and direct methanol fuel cells, solid polymer electrolyte additives, active cathode materials and bipolar plate interconnects. One of the desirable attributes afforded by the use of SWNTs in fuel cell applications stems from a combination of their extremely high electrical conductivity and large aspect ratios which results in a low weight percent for the electrical percolation threshold. This conductivity combined with the outstanding catalytic surface area offered by these nanostructured materials makes them a potentially outstanding active material for PEM electrodes. In addition, the high thermal conductivity, enhanced mechanical properties and corrosion resistance of polymer-SWNT composites may play a large role in developing new fuel cell designs such as thin-film microelectronic fuel cells. We will review the current applications involving SWNTs in PEM fuel cells and report on the recent work in the Nanopower Research Lab at RIT and it partners on utilizing high purity SWNT’s in microelectronic fuel cells.Copyright © 2003 by ASME

Wide band gap semiconductors are attractive for developing high power switching devices because of their ability to operate at both higher temperatures as well as higher frequencies than conventional Si. In this paper we report on the growth and fabrication of GaN/SiC np heterojunction diodes by depositing Si doped n-GaN films by plasma-assisted molecular beam epitaxy directly on SiC without the use of GaN or AlN buffers.Careful ex-situ and in-situ preparation of the Si terminated 6H- SiC surface was necessary to produce high quality diodes. Vertical circular diodes were fabricated with sizes varying from 200 microns to 1mm in diameter. Mesas were formed by ICP etching of the MBE deposited n-GaN layer using Cl2. A Ti/Al/Ni/Au metal stack was employed as an n-ohmic contact to the GaN layer and an Al/Ti/Au metal stack was employed as a backside p-ohmic contact to the 6H- SiC layer. The diodes were characterized by I-V and C-V measurements. The 1 mm diameter diodes exhibited almost ideal behavior under forward bias with an ideality factor of 1.6, and a reverse saturation current of 10–19 A/cm2. Under reverse bias, these devices were driven up to 1000 V with a measured leakage current of 5×10–7 A. and a dynamic resistance varying from 1010 to 109 ohms with increasing reverse bias. The built-in potential in these n-p heterojunctions was determined from C-V measurements to be 2.25 V. From these values we determined that the heterojunction is of Type II with conduction and valence bands offsets calculated to be 0.65 and 1.1 eV respectively.

A 2-year longitudinal observational study of 15 red deer farms was carried out in New Zealand from March 1992. Both years combined, 3364 adult and 653 yearling hinds were diagnosed pregnant in June by ultrasound scanning and monitored for reproductive success up to weaning. At weaning, pre-rut at approximately 100 days after calving, udders were palpated or observed by the farmer and hinds were categorised as lactating (wet) indicating survival of calf, or not lactating (dry). Farm management practices during calving and early lactation were recorded. Analysis of risk factors associated with progeny survival was done using path analysis (separately for adult and yearling hinds). Adult hinds3 years old at calving, conceiving before 1 May and having a body-condition score2 in September had 2.8, 2.4 and 2.9 times significantly higher odds of rearing a calf to weaning than other hinds, respectively. Adult hinds had about 5 times lower odds of rearing a calf to weaning when they were mixed with mature stags during calving. When farmers visited calving paddocks and checked for calving problems, adult hinds had 1.7 times higher odds of rearing a calf to weaning. When the farmer entered calving paddocks at least every second time they observed the hinds, yearling hinds had a twice higher odds of rearing a calf up to weaning. Sunny weather and high maximum temperatures were positively and negatively associated, respectively, with the probability of an adult hind being in lactation at weaning.

Newer diagnostic modalities such as serum markers and acute rest myocardial perfusion imaging (MPI) have been evaluated diagnostically in patients with chest pain in the emergency department (ED), but never concurrently. We compared these two modalities in distinguishing patients in the ED with symptomatic myocardial ischemia from those with non-cardiac causes.Serum markers and acute technetium-99m sestamibi/tetrofosmin rest MPI were obtained in 75 patients admitted to the ED with chest pain and nondiagnostic electrocardiograms. Venous samples were drawn at admission and 8 to 24 hours later for total creatine kinase, CK-MB fraction, troponin T, troponin I, and myoglobin. Three nuclear cardiologists performed blinded image interpretation. Coronary artery disease (CAD) was confirmed either by diagnostic testing or by the occurrence of myocardial infarction (MI).Acute rest MPI results were abnormal in all 9 patients with MI. An additional 26 patients had objective evidence of CAD confirmed by diagnostic testing. The sensitivity of acute rest MPI for objective evidence of CAD was 73%. Serum troponin T and troponin I were highly specific for acute MI but had low sensitivity at presentation. Individual serum markers had very low sensitivity for symptomatic myocardial ischemia alone. In the multivariate regression model, only acute rest MPI and diabetes were independently predictive of CAD.At the time of presentation and 8 to 24 hours later, acute rest MPI has a better sensitivity and similar specificity for patients with objective evidence of CAD when compared with serum markers.

A comprehensive epidemiological information system (EpiMAN-FMD) has been developed to assist national disease control authorities contain and eradicate outbreaks of animal diseases as efficiently and cost-effectively as possible. The system was initially developed to control an incursion of foot and mouth disease (FMD) or any clinically indistinguishable vesicular disease, although it has since been progressively expanded to manage other exotic and endemic diseases. Design objectives for the information management elements of EpiMAN-FMD included the following: the need to manage the vast quantities of data that eradication procedures for an FMD epidemic would generate within a very short time the ability to innovatively apply epidemiological understanding of disease spread to the data processing tasks the reduction of some of the foreseen processing bottlenecks the provision of decision support tools for data entry personnel. Design objectives for the veterinary management elements of the system included the following: the presentation of up-to-date status reports in formats that facilitate decision-making at the national or regional level the ability to optimise manpower resource allocation the capacity to evaluate the relative merits of alternative technical decisions, each of which carry different implicit risks. The system combines a multi-user database management system, expert system elements, various computer simulation models of specific aspects of FMD epidemiology and a range of statistical analyses designed to monitor the state of the epidemic. Although designed in New Zealand, EpiMAN-FMD has been constructed in a flexible style which makes adoption of the system possible in other countries with broadly similar 'stamping-out' contingency plans.

The rotation of trainee registrars in obstetrics and gynaecology to peripheral centres in South Australia was introduced for the first time in January 1998. A pilot study of the use of telemedicine to maintain the trainees’ involvement in the established weekly training sessions conducted at the Women's and Children's Hospital (WCH) was also commenced at the same time. Sessions were problem based and required the trainees to be actively involved throughout. An electronic voting system(EVS) was used by the WCH audience, with the results of all responses being seen at the peripheral centres. Initial evaluation of the EVS as an educational tool was sufficiently positive to justify further studies of its use in this environment. The availability of voting units at the peripheral sites, used in conjunction with the main centre, will provide an exciting opportunity for further research.

Economic analysis is a valuable technique in the planning and management of animal health programmes at the national policy level and at the level of individual livestock enterprises. Considerable experience has now been accumulated in the adaptation of methods of economics to address decisions on disease control issues. Different methods are appropriate for endemic diseases, for diseases which occur intermittently as local outbreaks, and for diseases which have the potential to cause an epidemic. A guide to the selection of the most suitable method is provided. The information required for analysis at individual herd level is much simpler than that required for national policy decisions and funding decisions by international agencies; an outline of the requirements for each level of analysis is provided. Issues surrounding the degree of risk of different choices are examined, and the application of decision analysis to higher-risk choices is introduced. Ways in which difficulties and hazards can be overcome are suggested for those unfamiliar with the techniques. Finally, procedures to provide confidence in the results of evaluations through sensitivity analysis are explained.

A 2-year observational study of 15 red deer (Cervus elephus) farms was carried out in New Zealand from March 1992. In each year of study, approximately 1650 hinds were individually monitored for reproductive success. During farm visits in March 1992 and 1993, five yearling and five adult hinds per farm were randomly selected and blood sampled to define their haematological, biochemical and blood mineral profile. Faecal samples were taken for parasite egg and larvae count. Biological markers potentially affecting the probability of conception before May 1 or of conception that year were investigated separately using multivariable logistic regression analysis. Adult hinds with low serum phosphorus concentrations were more likely to conceive before May 1. Lower conception rates were observed in yearling hinds when blood glutathione peroxidase, serum vitamin B12, and serum albumin concentrations were low, and when faecal lungworm larval counts were high. While these associations have yet to be proven as causal, data suggests that monitoring and maintaining adequate blood elements, and controlling internal parasites in yearling hinds, may assist farmers to achieve optimum reproductive performance in farmed red deer herds.

A 2-year longitudinal observational study of 15 red-deer farms was carried out in New Zealand from March 1992. Seven hundred yearling hinds were individually monitored for reproductive success. After mating, hinds were pregnancy tested by ultrasound and were classified as having conceived before 1 May, after 1 May, or as being not pregnant. Risk factors potentially affecting the probability of conception before 1 May or of conception that year were investigated using path analysis. To increase the probability of conceiving early, this study suggests yearling hinds should be selected prior to mating for high bodyweight and height. Young stags and hinds should be joined late summer (14 months of age) before mating. Mobs of yearling hinds should not be combined with large mobs of adult hinds. Paddocks with limited gullies, hills and trees should be chosen for mating. Finally, paddocks for mating should be away from human disturbance. To increase the probability of yearling hinds conceiving that year, yearling hinds should be in moderate-to-low body condition (around 2.5), and nutrition during mating should be prioritised to ensure optimal growth rates. Short and/or lightweight hinds may be mated successfully if they are well fed but they generally conceive later. Trees should be limited in the mating paddocks.

A longitudinal observational study of 15 red deer (Cervus elaphus) farms was carried out in New Zealand for 2 years from Mar 1992. Management of hind mobs and their composition during mating, calving, and weaning were recorded. About 2700 hinds were individually monitored for live weight, body condition score and reproductive success. All hinds were pregnancy tested in June by ultrasound and classified as having conceived before May 1, after May 1, or as being not pregnant. Calving dates and dam-offspring pairs were recorded on four farms. The lactational status of hinds and live weight of calves were recorded at weaning. Mean pre-mating live weights of yearling hinds were 81.3-82.8 kg and of adult hinds 98.0-98.7 kg, respectively, for each year of study. The percentage of yearling and adult hinds conceiving before May ranged from 8.3 to 95.0% and from 77.6 to 98.4%, respectively, between farms. Overall, the proportion of yearling and adult hinds not pregnant was 15.3% and 3.2%, respectively. Pregnancy rates at scanning of adult hinds within mating mobs were generally over 90%, and 41.7% of mating mobs had 100% pregnancy rates. In contrast, the pregnancy rates of yearling hind mobs were more variable, with five mobs below 50%, and 34.1% of mating mobs achieving 100% pregnancy rate. Estimated in utero loss rates from pregnancy diagnosis to calving were 0.66 and 0.79% for yearling and adult hinds, respectively. From four farms, median calving dates of yearling and adult hinds were Dec 13 and Nov 30, respectively. Overall, calf survival rates to weaning of yearling and adult offspring were 84.1 and 91.6%, respectively, while the reproductive efficiencies (number of calves weaned per hind mated) were 70 and 83.6%, respectively. Farm mean weaner live weights standardised on Apr 1 ranged from 42-59 kg and 39-51 kg for stags and hinds, respectively. These data are currently the best estimates of reproductive parameters of New Zealand red deer herds, and highlight a wide variability in reproductive indices between farms.

During an outbreak of classical swine fever (hog cholera) or African swine fever, decisions in emergency headquarters have to be made under conditions of time pressure, limited resources and uncertainty. The computer program EpiMAN-SF is designed to support decision-making in this situation by providing up-to-date information and a structured approach to choosing from among competing tasks by combining electronic data management with expert system components. EpiMAN-SF provides accurate and timely summaries of the epidemic, using both text and graphics. In addition, the program provides tools for the epidemiological analysis and forecasting of the emergency, and for assessing current and alternative control strategies. The expert system and simulation models integrated in EpiMAN-SF have been evaluated using sensitivity analysis, historic outbreak data and expert opinion. The results demonstrate that EpiMAN-SF is a valid alternative to traditional data management during exotic disease epidemics.

Due to stable myocardial retention and technetium imaging characteristics, 99mTc-tetrofosmin has been considered potentially useful for acute chest pain imaging. Tetrofosmin also has favorable biokinetics with reported rapid liver clearance, 5 min poststress and 30-45 min post-rest injection. Since comparable data are not available, the effect of time on liver clearance was evaluated in patients with acute chest pain.One hundred six patients received an intravenous injection of 25-30 mCi 99mTc-tetrofosmin to evaluate acute chest pain. SPECT imaging was performed 15-120 min after injection of the tracer. Patient images were grouped according to the time of acquisition after acute injection: 15-30 min, 31-45 min, 46-60 min, 61-90 min and90 min. Quantitative analysis was performed of a similar anterior projection for each patient consisting of 6 X 6-pixel region of interest over the myocardium and adjacent liver. Average counts per pixel were determined and a heart/liver (H/Li) ratio was calculated.The mean H/Li ratio was1.0 for patient images acquired 15-45 min after injection, and1.0 for patient images acquired after 45 min. The difference was statistically significant (p0.05).Quantitative analysis suggests that the optimal imaging time should be at least 45 min after the injection of 99mTc-tetrofosmin to allow adequate liver clearance before image acquisition of acute chest pain syndromes.

The optimal orbit for myocardial SPECT imaging has not yet been determined. In order to evaluate differences in image quality and reader interpretation between orbiting methods, 50 patients scheduled for routine stress/rest 99mTc-sestamibi imaging had both a circular and a noncircular study using an ADAC Vertex dual-head imaging system.Each study was acquired using a 64 x 64 matrix, 64 stops at 25 sec per stop. Images were processed using a Butterworth filter with a frequency cutoff of 0.6 and an order of 5.0. Studies were interpreted by three experienced readers without knowledge of patient name or orbiting technique for normal and abnormal segments and overall image quality.There was no significant difference in the semi-quantitative assessment of either defect extent or reversibility or in the quantitative assessment of defect size between the two types of orbits. However, while all 50 noncircular studies were read as good or fair quality, 23 circular studies were read as fair or poor (p =0.0002).Qualitative and quantitative analysis revealed similar size and extent of perfusion defects using either circular or noncircular orbit, but images with the noncircular orbit were of significantly better image quality and may be preferable to a circular orbit with 99mTc-sestamibi.

This research effort sought to demonstrate that combining select phosphonic acid additives with Nafion could improve Nafion's high temperature electrochemical performance. A 1:1 mixture of the additive with Nafion, resulted in a film that demonstrated 30% higher conductivity than a phosphoric acid equilibrated Nafion control at 175°C. This improvement to the high temperature conductivity of the proton exchange membrane Nafion is without precedent. In addition, thermal analysis data of the test films suggested that the additives did not compromise the thermal stability of Nafion. The results suggest that the improved Nafion proton exchange membranes could offer superior electrochemical performance, but would retain the same degree of thermal stability as Nafion. This research could eventually lead to portable fuel cells that could oxidize unrefined hydrocarbon fuels, resulting in wider proliferation of fuel cells for portable power.

The superficial and deep lymphatic systems of the Australian brushtail possum (Trichosurus vulpecula) are described. In common with other marsupials studied to date and in contrast with most eutherians, there were no popliteal lymph nodes and efferent drainage from the inguinal lymph centre passed directly to the deep axillary group of lymph nodes via an inguinoaxillary trunk. Efferent vessels from the tonsil passed directly to the deep cervical lymph node, which was drained by the tracheal trunk. The mandibular and parotid lymph nodes drained independently to the superficial cervical lymph node. All subcutaneous lymph drainage passed either through the superficial cervical or the axillary lymph centres before entering the venous system, an arrangement which is also found in kangaroos. The significance of the patterns of lesion distributions in possums with naturally occurring tuberculosis caused by Mycobacterium bovis is discussed.

Insulin-like growth factor (IGF-I) action is influenced by circulating as well as tissue levels of its binding proteins. Because serum IGF binding protein-1 (IGFBP-1) levels have been found to be decreased in patients with polycystic ovary syndrome (PCOS), we tested the hypothesis that regulation of IGFBP-1 secretion may be different in patients with PCOS compared with normal women.We studied 15 normal ovulatory women and 15 women with PCOS of similar age (21 +/- 1 and 22 +/- 1 years, respectively). All subjects were studied after an overnight fast between days 5-8 after spontaneous or progestin-induced menses. Perturbations included the administration of insulin intravenously, maintenance of a euglycemic clamp, and, in a subsequent cycle, the administration of a long-acting somatostatin analogue (octreotide, 100 micrograms) given subcutaneously. Blood samples were collected before treatment, every 15 minutes for 6 hours after insulin, and every 30 minutes for 3 hours after octreotide administration. Serum levels of IGF-I, IGFBP-1, IGFBP-3, and insulin were measured by specific immunoassays.Compared with the controls, patients with PCOS had significantly higher insulin levels, similar IGF-I and IGFBP-3 levels, and significantly lower IGFBP-1. Insulin did not change serum IGF-I levels in either group, although a significant decrease in IGFBP-1 levels occurred in normal women but not in patients with PCOS. Octreotide treatment also did not change serum IGF-I levels in either group, but serum insulin levels decreased significantly and IGFBP-1 levels increased significantly in both groups; this response was significantly greater in controls.Our data are compatible with the notion that regulation of IGFBP-1 is altered in women with PCOS and that several factors may be involved.

To evaluate the performance of a conservative treatment protocol for ovarian hyperstimulation syndrome (OHSS) that utilized low-dose dopamine, volume expanders and diuretics.Prospective, open trial.Thirteen patients met the criteria for diagnosis of severe OHSS during the study period. Two of these were in vitro fertilization (IVF) patients who did not undergo transfer and so were excluded from analysis. Of the remaining 11, 10 (91%) were pregnant. The average time for resolution of the OHSS and discharge from the hospital was 6 days (range, 2-11). Compared to levels at admission, there was no significant difference in those of sodium, potassium or creatinine after resolution of the syndrome. Hemoglobin and hematocrit, however, were significantly reduced (P.03). There were no cases of adult respiratory distress syndrome or thrombosis. No pregnancies were interrupted.Conservative treatment of OHSS is an acceptable form of management. Risky and invasive therapies, such as paracentesis, are not warranted.

The purpose of this experiment was to determine whether use of the angiotensin-converting enzyme (ACE) inhibitor, enalapril, would prevent the occurrence of ovarian hyperstimulation syndrome (OHSS) in the rabbit model. A total of 20 adult female New Zealand white rabbits were studied. All rabbits received 75 IU of human menopausal gonadotrophin s.c. each day for 7 days. On day 8, all rabbits received 2500 IU of human chorionic gonadotrophin (HCG). Ten rabbits were randomly chosen to receive enalapril orally. Five received 1 mg/kg of enalapril and five received 2 mg/kg of enalapril twice daily. The remainder received placebo orally twice daily. On day 10, all rabbits underwent surgical exploration. Total body weight was found to increase significantly in the placebo group (by 293 g, P0.001) but not in either group receiving enalapril. Haematocrit also increased significantly in the placebo group (by 3%, P0.013) but not in the enalapril groups. Ovarian weights were highest for the 2 mg/kg enalapril group (5.80 +/- 0.52 g), followed by the 1 mg/kg enalapril group (3.64 +/- 0.45), and least for the placebo group (2.69 +/- 0.17). All 10 placebo rabbits met criteria for severe OHSS whereas only six in the enalapril groups did. We concluded that angiotensin II may play a significant role in the development of weight gain, third space fluid accumulation and intravascular fluid depletion in OHSS. ACE inhibition resulted in a 40% decrease in the incidence of OHSS in the rabbit model.

To determine whether angiotensin-converting enzyme (ACE) inhibition would affect ovarian steroid synthesis in the oocyte donors undergoing controlled ovarian hyperstimulation (COH).The IVF program of the University of Southern California.Prospective matched clinical trial.Twelve oocyte donors were studied in 28 hyperstimulation cycles.Donors underwent a standard COH protocol. Follicle aspiration was performed 34 hours after administration of hCG. After the procedure, seven donors were administered the ACE inhibitor, captopril, 6.25 mg orally twice daily for 4 days. The remaining patients served as controls.Serum E2, P, plasma prorenin, active renin, and angiotensin II (Ang II).Angiotensin II increased after aspiration in both groups but was significantly lower in those receiving captopril. Peak P in the captopril group was significantly lower than controls (81.8 +/- 27.8 versus 208.5 +/- 23.9 ng/mL [conversion factor to SI unit, 3.180]). Peak E2 was significantly higher (2,222.4 +/- 875.3 versus 425.6 +/- 490.4 pg/mL [conversion factor to SI unit, 3.671]). Active renin and Ang II correlated with P.In stimulated cycles, inhibition of Ang II production appears to raise serum E2 and lower P levels. Angiotensin II, therefore, may have a role in the regulation of ovarian steroid synthesis.

Ovarian hyperstimulation syndrome (OHSS) is a serious complication of gonadotrophin usage but it is difficult to accurately predict its occurrence. Previous investigators have identified the combination of high oestradiol concentrations and oocyte number as being predictive in 80% of cases. In this study we sought to identify the incidence of severe OHSS in patients with high oestradiol concentrations and large numbers of oocytes and to evaluate the importance of pregnancy in the development of OHSS. Between 1990 and 1993, we studied 139 cycles using two assisted reproductive techniques [oocyte donor, n = 72; in-vitro fertilization (IVF), n = 67] in which either oestradiol (4000 pg/ml), oocyte number (25), or both were elevated. OHSS was diagnosed by standard criteria. There were no cases of severe OHSS in the oocyte donor group and six in the IVF group. Among 10 patients with oestradiol concentration6000 pg/ml and30 oocytes, only one had OHSS (10%). The relative risk of OHSS with pregnancy was 12 (confidence interval 2.18-66.14). We conclude that the risk of OHSS even at high levels of stimulation is lower than previously believed. Secondly, donors have a very low risk of OHSS, probably because of the absence of pregnancy. As such, cryopreservation of all oocytes in IVF cycles is a reasonable alternative to cycle cancellation or use of adjunctive medication.

The isolated finding of polycystic-appearing ovaries on ultrasound examination of normal women is not uncommon. The purpose of this study was to determine the clinical significance of polycystic ovaries in a population of healthy, non-hirsute, fertile women preparing to undergo ovarian stimulation. We evaluated whether the finding of polycystic ovaries in oocyte donors predicts a different response to ovarian stimulation when compared to donors with normal-appearing ovaries. Furthermore, we examined whether oocytes from polycystic ovaries had the same capacity for fertilization and development as those retrieved from normal ovaries. In all, 11 donors with polycystic-appearing ovaries were compared prospectively to 13 donors with normal-appearing ovaries who were undergoing ovarian stimulation during the same time interval. The two groups were similar in age and baseline androgen concentrations. Significantly more oocytes were produced by the polycystic group for the amount of human menopausal gonadotrophin (HMG) administered (P0.05). In addition, all previous cycles completed by these 24 donors were compared (polycystic group: total of 31 cycles; normal group: total of 37 cycles). The donors with polycystic ovaries required less HMG to obtain optimal stimulation (P0.05), attained a greater peak oestradiol concentration (P0.05), produced a greater number of follicles (P0.05) and oocytes (P0.01) and a higher percentage of mature oocytes (P0.05). Furthermore, they achieved a higher peak oestradiol/HMG (P0.01) and oocytes/HMG ratio (P0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical impressions suggest the presence of considerable anxiety and depression in infertile couples. We utilized a psychological stress test to assess adaptations to provoked stress to improve the psychological profile of infertile women. A psychological stress test was administered to four groups: normal menstruating females (controls, n = 13); oocyte donors (n = 13); recipients of oocyte donation (n = 7); and women undergoing standard in-vitro fertilization (IVF; mean age 38.0 years; n = 8). The psychological stress test consisted of three active coping tasks: (i) serial subtraction, (ii) Stroop colour test, (iii) speech task and (iv) one passive coping task, the cold-pressor test. Haemodynamic responses (HD) were monitored before, during and after the psychological stress test, and serum samples were drawn for catecholamines and cortisol. Baseline blood pressures were similar among groups. The psychological stress test elicited different biophysical responses in controls compared with the other groups (P0.001). Oocyte donors had different speech task responses from baseline, although these and the other parameters of the psychological stress test were not different from either the recipient or IVF groups. Blood pressure responses from baseline were blunted in both recipients and standard IVF patients following provoked stress. Baseline cortisol and norepinephrine were similar among all groups, yet provoked stress elicited a significant increase in controls (142.0 +/- 25.2%, P0.001) compared with oocyte donors (17.1 +/- 19.7%), recipients and standard IVF patients (mean -15.5 +/- 17.3% respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

A 2-year observational study was conducted on 15 commercial red-deer farms in the North Island of New Zealand, to provide health and production data, and identify risk factors for outcomes including health, reproduction, venison and velvet antler production. About 2,700 hinds, 2,400 weaner deer and 1,500 stags were monitored. Daily management practices, deer performance and health problems were recorded. At 3-monthly visits, samples were collected from deer, pastures and soils. Data were processed by multivariable statistical techniques to identify the most important factors affecting production and health.

A 2 yr observational study of 15 commercial red deer farms is being conducted in New Zealand and statistical analysis initiated. Preliminary results for weaner deer growth, reproduction and deer mortality data are presented. Multivariable statistical analyses are used to identify risk factors for these various outcomes. Factors associated with yearling hind conception status were included in a putative path diagram and logistic regression was used to identify important factors.

Ovarian failure is heterogeneous in etiology and may occur at various points in a woman's life. As such, it may interfere with fertility. Clinical presentation ranges from complete cessation of menses to oligomenorrhea to the continuation of menses with elevated gonadotropins. Various therapies have been used in an attempt to induce fertility, including sex steroids and gonadotropin-releasing hormone agonists to suppress circulating gonadotropin alone or in combination with estrogen or gonadotropin-releasing hormone agonists to induce ovulation. Corticosteroids are also used to overcome autoimmunity. Randomized therapeutic trials are rare and fail to demonstrate any significant improvement in ovulation and pregnancy rates. Donor oocytes have demonstrated high success rates and have proven to be useful in patients with both premature ovarian failure and natural menopause. Pregnancies have been initiated and maintained in women through 60 years of age. Thus, for those accepting of the technique, oocyte donation appears to be the treatment of choice for hypergonadotropic hypogonadism.

Geographic information systems (GIS) are computerised information systems that allow for the capture, storage, manipulation, analysis, display and reporting of geographically referenced data. They have been used in recent years for a wide variety of purposes, including town planning and environmental resource management. The technology has many features which make it ideal for use in animal disease control, including the ability to store information relating to demographic and causal factors and disease incidence on a geographical background, and a variety of spatial analysis functions. A number of possible veterinary applications are suggested, and three examples of the use of GIS in New Zealand are discussed.

As in most other technical and management fields, information management is fast becoming the key to effective action in animal health. A modern veterinary service requires effective systems for gathering relevant information from the field, processing it in ways which provide maximum value, and presenting it in a form which is easy for national policy-makers and field staff to use in implementing appropriate actions to achieve effective disease control. This paper describes seven objectives which should form the basis for developing an integrated national animal health information system. It also specifies six criteria which any information-gathering activity should be required to meet before it is allowed to commence. For each of the seven objectives, a description is given of how the particular component of the system can be used, with examples of how such information management procedures have been implemented in practice. Attention is drawn to other papers in this issue which describe various innovative techniques currently used to meet some of the objectives of a modern animal health information system.

SUMMARY: Tracer sheep were used to determine the temporal distribution of acquisition ofF. hepatica on both irrigated and non-irrigated areas an area of northern Victoria where this parasite is endemic, for the period November 1974 to November 1976. Throughout the study, very few flukes were acquired on the non-irrigated experimental area, and of this small number most were acquired by sheep in late spring and early summer. Flukes were acquired throughout both experimental years on the irrigated experimental area. The intensity of infection was lowest in late winter and early spring, but acquisition was substantial when measured over a year, being 483.5 in the first year and 1234.6 flukes per sheep in the second year. The productivity of these animals was lower than that of equivalent animals kept on an area free of fluke, but quantitative interpretation of this information is confounded by the effect of the presence of an area with atypically high moisture levels (the snail habitat) on pasture production in the area grazed by the infected animals. The differences recorded are therefore likely to be underestimates of the true difference. A suitable treatment regimen for control of liver fluke in sheep in northern Victoria is outlined.

There is a substantial literature describing the various methods of job evaluation, all of which are essentially concerned to rank different jobs in a pay hierarchy according to rational criteria. Also, the aims and effectiveness of job evaluation schemes in terms of labour cost containment and as an aid to economic growth have been extensively discussed and evaluated. Moreover, in an era of incomes policies and the relative decline of industrywide bargaining, commentators have explored the feasibility of national job evaluation or alternative procedures for the consolidation of consistent acceptable differentials or ‘relativities’ between different work groups and industries at the level of the economy.

The productivity of 24 Corriedale weaner wethers in eight groups of 3, artificially infected with a range of fluke burdens, was studied by measuring body weight change, midside patch wool growth, fleece weights and feed digestibility over a period of 24 weeks. Data from bodyweight and patch wool measurement and feed digestibility were analysed by regression procedures. All parasitised groups exhibited a reduction in growth rate, patch wool growth and fleece weight, when compared with the control groups. Reduction in feed conversion efficiency was detected in groups having mean burdens of 45, 67 and 117 flukes. Because groups with mean burdens of 230 or more flukes had reduced feed intake, and sheep in these groups died, the feed conversion information from these groups cannot be considered unequivocal. The group mean liveweight changes, patch wool growth and fleece weights were closely related to the mean number of flukes in the respective group. Prediction equations for wool growth rate and body weight gain in fluke infected sheep are presented.

Economic benefits obtained from two schemes for the anthelmintic control of helminthiasis in breeding ewes and their lambs have been assessed in the Western District of Victoria. The results were compared with those from sheep receiving no anthelmintic treatment, and also with those from sheep given anthelmintic every 2 weeks. The results reported in this paper cover the wool-growing years 1971–1972 and 1972–1973, and represent the continuation of a study commenced in 1970. The “critical” treatment scheme yielded the highest net return under all circumstances in both years. The actual net benefit per 100 sheep, in comparison with “no treatment”, was A$213 and 255, respectively; results which were not sensitive to variation in wool prices or animal productivity. The benefit was derived principally from higher fleece weight per ewe, higher prices per kilogramme for better quality wool and, to a lesser extent, from higher values for ewes and lambs. Because net returns from “traditional” treatment groups were lower, A$ 95 and 103, respectively, and were sensitive to variations in animal productivity, this scheme could not be recommended for routine use.

SummaryA detailed study of the bionomics ofGlossina longipalpis, Wied., was undertaken at Takoradi, the principal port of the Gold Coast in West Africa, and lasted from February to September 1931.The topography of this country is undulating; the vegetation is of Transition Forest type, intermediate in character between Rain Forest and Savannah Forest, and of an exceedingly dense, homogeneous nature, with a few small glades in the forest, and interrupted by large open marshes on the lower and flatter ground.The climate is remarkably equable, with a low mean annual rainfall between 40 and 45 inches, but constantly high humidities, owing to the moisture-laden sea-winds. There is a double rainy season, the main rains from April to July, and a second shorter period of rainfall in October and November.There is a rich mammalian fauna, with the exception of the larger game animals.Three species ofGlossinaoccur:G. longipalpis, Wied., the commonest, evenly distributed throughout the bush, and the only species dealt with in this paper;G. palpalis, R.-D., confined to water-courses and the edges of lagoons; andG. medicorum, Aust., rarely met with.Two isolated fly-belts, identical in every way, were studied. In one, section A, flies were caught and killed daily; in the other, section B, the control area, the flies were liberated after noting the catches. By September, the tsetse population of A had been reduced to less than one-third of that of B, presumably the effects of catching and killing.The main food hosts of this species were the bushbuck and duiker, ubiquitous in this forest. When these small game animals were driven out of a third fly-belt, section C, by farming and wood-cutting, the fly quickly and completely disappeared. This species was never found to feed on reptiles, although they were common in the fly-belts.Meteorological observations in the open country and in the fly-belts showed a consistently lower temperature and higher humidity in the latter, as well as its greater equity in these factors. The movement of the fly into the open was apparently governed by humidity, the greatest movement taking place when the humidity of the open was within the normal range of fly-belt humidity.By statistical methods, coefficients of correlation were determined for the fly's density-activity and various climatic factors of the fly-belt. The fly showed a high positive correlation with temperature, and a lower correlation with humidity, of which saturation deficit was a better index than atmometer evaporation. There was a significant correlation with sunshine, but none with rainfall. This correlation with humidity was mainly a temperature effect, as was also the correlation with sunshine. Temperature was evidently of major importance. There was a significant negative correlation between fly and relative humidity, measured with a wet and dry bulb hygrometer in a screen in the open.All correlations were greatest when considered direct, the fly catches with simultaneous climatic readings, indicating that these factors influence the activity of the fly in this way, rather than its density. The fly was found to be inactive at temperatures below 74°F., with high humidities of 80 or 90 per cent. or over. This explains the major influence of temperature, shown by the methods of correlations. The temperature range in the fly-belt, during the period of observations, was close to the temperature significant for the fly's activity, and therefore variations produced marked reactions; the humidity range was much closer to the fly's optimum and therefore better tolerated.There is marked daily rhythm in the fly's activity, which is only influenced by climate under extremely unfavourable conditions of temperature or humidity.The distribution ofG. longipalpisin the Gold Coast is dependent upon the humidity of the ecoclimate, rather than upon temperature. It occurs in three main vegetational types—Transition Forest, Inland Savannah Forest, and Coastal Savannah— where the range of humidities is between 50 and 80 per cent. R.H., and temperature between 75° and 85°F. It does not occur in the Rain Forest, where the relative humidity is constantly above 80 per cent., or in northern Savannah, where the humidity is as low as 30 per cent, in the dry season.The main breeding season was from March to July with its maximum in May, at the height of the rains.This species was found infected withTrypanosoma gambiense,T. congolense, andT. vivaxat Takoradi, and is probably second in importance toG. palpalisas a vector of sleeping sickness in the Gold Coast, but at present of less importance thanG. palpalisorG. tachinoidesin the transmission of trypanosomiasis of stock.The receding of the Ashanti forest and the present development of the Colony may cause even greater contact between this species of tsetse and man. The main policy for control should lie in improving and controlling the natives' methods of cultivating the bush. Farms should be as close to the village as possible, contiguous, and kept under cultivation, if possible, permanently. Clearings should be made of at least 100 yards width round bush villages, and of at least 200 yards width round important towns. Small clearings and isolated farms are considered a danger.

Eupelmella vesicularis Retz. was found in certain parts of Hungary infesting cocoons of Diprion sertifer Geoff. already parasitized by a primary parasite, Microplectron fuscipennis Zett. It was never found in the absence of this chalcid.Experiments showed that Eupelmella confined itself almost exclusively to Microplectron as a host, easily detecting the presence of larvae or pupae of this parasite within the cocoons of the saw-fly host, but neglecting eggs.A single egg is laid per cocoon and the larval Eupelmella eats from 10 to 20 Microplectron larvae or pupae, and finally kills all the remaining living parasites within the cocoon before pupating.The egg and larva show interesting structural adaptations for this mode of life.Reproduction is parthenogenetic and no males are known.Several factors combine to make this insect a dangerous enemy of Microplectron capable of seriously impairing its efficiency. These are: its selective ability, its destructive powers, its rapid rate of increase due to the parthenogenetic habit, and its ability to establish itself and survive on small numbers of the prey, for the same reason.

A combination of historical, geographical, and epidemiological studies has given sufficient insight into the ecology of sleeping sickness to enable the main factors influencing the development and spread of an epidemic to be traced.The evidence shows that in West Africa sleeping sickness is not primarily a disease of the forest, where tsetse flies are most abundant, but belongs essentially to the dry country in the north of the savanna woodland zone, where the earliest occurrences and severest outbreaks have been located.The first mention of sleeping sickness comes from the upper Niger and dates back to the 14th century. By the beginning of the present century intense though localised epidemics were devastating parts of the Mossi, Grounsi and Lobi country of the upper Volta rivers. At this time the disease was unknown on the coast and of sporadic occurrence only in the forest. A severe trans-Volta epidemic covering 60,000 square miles, developed between 1924 and 1940, but was confined to the north of the inland savanna zone with nothing comparable in the forest.The epidemic spread in three principal ways : (1) Outwards from original foci of infection because of the dynamic nature of the disease. This produced a concentration of infection around headwaters, a feature characteristic of advanced epidemics. (2) Through the agency of travellers, originally from north to south but subsequently in both directions : a rapid method of spread producing linear distribution of infection along trade routes. The tempo was greatly increased on the pacification and development of West Africa after 1900. (3) A gradual southward shift in the main epidemic zone appears to be resulting from a long-term change in the African climate which is combining with man's activities to produce a southerly extension of xerophytic vegetation types and a regression of forest.The most important spread was that caused by the trading caravans, more especially the cola traders, who have been coming down to the cola-nut areas in the Ashanti forest from the big markets on the Niger and Upper Volta since the 11th century. The caravans were formerly very large, up to one or two thousand strong, and were frequently made up of Mossi and Grounsi from the territory that was so heavily infected by the beginning of the present century. It is certain that a continuous introduction of infection would have been taking place into the forest ever since trypanosomiasis was prevalent in the north, that is for 100 years at least. And infection has been known in the forest for about that period, yet always to a mild degree, never reaching epidemic form. It has been sought for, because conditions in the forest, with the vector Glossina palpalis in contact with every village and path, appeared to be ideal for the transmission of infection and this drew the particular attention of the early workers from 1908 onwards. But the most that could be found was a threatened epidemic in north-west Ashanti, very significantly centering on the big cola markets which formed the termini for the northern traders.This historical evidence and the reasoning from epidemiology lead to the conclusion that conditions in the forest are not conducive to the development of epidemic sleeping sickness and that the low state of endemicity found there is maintained by the constant introduction of infection from the true epidemic areas in northern savanna.From this conclusion arises a practical point of the greatest importance. If the sources from which infection is introduced into the forest could be eliminated the disease there should eventually die out and the tsetse, from the human point of view, would be harmless. Tsetse control in the forest may prove difficult and expensive, and if it is attempted by clearing this might end in the literal destruction of the forest. Such measures would be hard to justify, so many other factors of possibly greater importance than trypanosomiasis are involved, both the intrinsic value of a forest for its products and the wider value through its influence on climate, soil and water.In formulating a plan for the control of sleeping sickness, the habits of both vectors, human as well as insect, should be considered. The tsetse plays a major role in the development of the high infection rates characterising the epidemic outbreaks in northern savanna ; the human vector distributes infection from these sources along trade routes and into the forest. The elimination of the disease at its source, in true epidemic centres, which can be most effectively accomplished by eradication of the tsetse, will check the distribution of infections to the secondary areas of lighter infection which could then be cleared up by quite minor control measures or might even disappear spontaneously.This plan is now in operation in the Gold Coast. The validity of the arguments on which it was based is being shown by the results that are already apparent : the high rates of reduction in the epidemic areas and the pronounced lowering of infection in neighbouring, uncontrolled areas, more particularly in the forest region of north-west Ashanti where it is entered by a trade route coming from the previously heavily infected country.

1. Primary fly-belts round Makongo consisted of three different vegetational communities: a Cynometra-Vitex association along the main length of the Makongo river, on a clay soil; a Ficus congensis association along the river close to the town, on a sandy soil; and Isoberlinia doka woodland on moist sandy soil north-west and south of Makongo.2. Secondary fly-belts of less dense vegetation occur in the orchard bush savannah round Makongo, and these are not colonised until the commencement of the rainy season.3. Glossina tachinoides and G. palpalis both occurred in the riverside communities, and G. palpalis alone in the Isoberlinia woodland.4. Along the river G. palpalis outnumbered G. tachinoides by 3:1 in the dry season. At the commencement of the rains G. tachinoides increased more quickly than G. palpalis, bringing their numbers very nearly equal, but at the end of the rains there was a decrease in G. tachinoides which restored the original proportion.5. G. morsitans had been found at Makongo formerly but was not met with at the time of this investigation, its absence being due to the disappearance of the larger antelope from the neighbourhood.6. Smaller game animals, small mammals and reptiles afforded an adequate food supply for tsetse in the fly-belts, and also passing herds of cattle, as well as natives from the village and travellers.7. The distribution of G. palpalis within the fly-belts was markedly influenced by the proximity of a cattle road along which herds of cattle passed almost daily, and by village water-holes.8. During the dry season the primary foci were always found to be the places of greatest relative humidity, and the fly does not tend to move out of these until the general atmospheric humidity has reached a certain fairly high degree.9. In clearing the fly-belts the removal of all primary foci within a quarter of a mile of the town and of thick bush within 100 yards of water-holes was undertaken. The work lasted from the beginning of February to the end of March 1931.10. The effect of clearing the Isoberlinia doka woodland was to banish G. palpalis completely, and it never returned to these clearings.11. On clearing the riverside Ficus congensis fly-belt, G. tachinoides was practically eliminated for the first three months, but reappeared in the clearings in June when there was a general increase and up-stream migration of this fly. G. palpalis remained in this clearing in fluctuating numbers up to June, when observations were suspended.12. 565 marked tsetse were liberated in the fly-belts immediately previous to clearing. Of G. palpalis 12·7% were recaptured in the clearings and 11% outside the clearings. Of G. tachinoides 5·5% were recaptured in the clearings and 6·8% outside.

Summary Under the conditions of tropical rain forest and secondary forest in Liberia it was found that surveys of the tsetse fly Glossina palpalis, the vector of Gambian sleeping sickness, could be more efficiently carried out by traps than by the conventional method of hand catching with fly-collectors. Unbaited traps, 2 feet high and 2 feet long, covered with natural burlap, were adopted because they gave a uniform rate of sampling. Traps twice as large caught more tsetse but were difficult to standardize. Folding traps, more easily carried than the rigid standard type, were equally effective in a short trial. In direct comparisons, four traps caught as well as two collectors in low densities of G. palpalis, with a marked superiority during the dry season, when their catches gave a truer index of the numbers of tsetse present. In high densities of this species, traps gave a better performance than men, since their rate of catching was unaffected by the numbers of tsetse to be caught. It is economical to employ traps, but not men, for detecting flies at very low densities. Traps can be used to measure the factor “man-fly contact.” Comparability requires a standard procedure in visiting traps. The catches obtained with daily visits are nearly doubled with visits twice a day, and fall to 70% with visits on alternate days and to below 40% when visited twice a week. These differences are due both to the escape of flies between visits and to the attraction of tsetse to the traps by hosts each time a trap is visited. These traps could be used also for surveys of tabanids and other insects.