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We examine the capability of the Global Modeling Initiative (GMI) chemistry and transport model to reproduce global mid-tropospheric (618 hPa) ozone–carbon monoxide (O3–CO) correlations determined by the measurements from the Tropospheric Emission Spectrometer (TES) aboard NASA's Aura satellite during boreal summer (July–August). The model is driven by three meteorological data sets (finite-volume General Circulation Model (fvGCM) with sea surface temperature for 1995, Goddard Earth Observing System Data Assimilation System Version 4 (GEOS-4 DAS) for 2005, and Modern-Era Retrospective Analysis for Research and Applications (MERRA) for 2005), allowing us to examine the sensitivity of model O3–CO correlations to input meteorological data. Model simulations of radionuclide tracers (222Rn, 210Pb, and 7Be) are used to illustrate the differences in transport-related processes among the meteorological data sets. Simulated O3 values are evaluated with climatological profiles from ozonesonde measurements and satellite tropospheric O3 columns. Despite the fact that the three simulations show significantly different global and regional distributions of O3 and CO concentrations, they show similar patterns of O3–CO correlations on a global scale. All model simulations sampled along the TES orbit track capture the observed positive O3–CO correlations in the Northern Hemisphere midlatitude continental outflow and the Southern Hemisphere subtropics. While all simulations show strong negative correlations over the Tibetan Plateau, northern Africa, the subtropical eastern North Pacific, and the Caribbean, TES O3 and CO concentrations at 618 hPa only show weak negative correlations over much narrower areas (i.e., the Tibetan Plateau and northern Africa). Discrepancies in regional O3–CO correlation patterns in the three simulations may be attributed to differences in convective transport, stratospheric influence, and subsidence, among other processes. To understand how various emissions drive global O3–CO correlation patterns, we examine the sensitivity of GMI/MERRA model-calculated O3 and CO concentrations and their correlations to emission types (fossil fuel, biomass burning, biogenic, and lightning NOx emissions). Fossil fuel and biomass burning emissions are mainly responsible for the strong positive O3–CO correlations over continental outflow regions in both hemispheres. Biogenic emissions have a relatively smaller impact on O3–CO correlations than other emissions but are largely responsible for the negative correlations over the tropical eastern Pacific, reflecting the fact that O3 is consumed and CO generated during the atmospheric oxidation process of isoprene under low-NOx conditions. We find that lightning NOx emissions degrade both positive correlations at mid- and high latitudes and negative correlations in the tropics because ozone production downwind of lightning NOx emissions is not directly related to the emission and transport of CO. Our study concludes that O3–CO correlations may be used effectively to constrain the sources of regional tropospheric O3 in global 3-D models, especially for those regions where convective transport of pollution plays an important role.

This work advances laser absorption spectroscopy with measurements of aluminum monoxide (AlO) temperature and column density in extreme pressure (P > 60 bar) and temperature (T > 4000 K) environments. Measurements of the AlO A2Π i –X2Σ+ transition are made using a microelectromechanical system, tunable vertical cavity surface emitting laser (MEMS-VCSEL). Simultaneous emission measurements of the AlO B2Σ+–X2Σ+ transition are made along a line of sight that is coaxial with the laser absorption. Absorption temperature fits agree with emission spectra for a T = 3200 K, P = 9 bar case. In cases with T > 4000 K, P > 60 bar, absorption fits match the ambient temperature while emission fits over-estimate it, owing to high optical depths. These data juxtapose passive and active spectroscopic methods and demonstrate the versatility of AlO laser absorption in high-pressure and high-temperature environments where experimental data remain scarce, and engineering models will benefit from refined measurements.

The protective aluminum oxide film naturally formed on a surface of aluminum has a thickness in the range of 3–5 nm. Its melting causes loss of its continuity, which may significantly affect the ignition and combustion processes and their relative time scales. Melting of the alumina film also plays an important role when aluminum powders are used to prepare composites and/or being sintered. This letter quantifies depression of the melting point of an alumina film based on its nano-meter thickness. A theoretical estimate is supported by experiments relying on a detected change in the optical properties of naturally oxidized aluminum particles heated in an inert environment.

P92 steels are commonly used in advanced steam generating power plants with welding being a main method of component fabrication. Such welds are typically post-weld heat treated at temperatures up to 780°C, which is designed to be as high as possible without the danger of the formation of any austenite during the heat treatment itself. Moreover, it is recognised that, in practice, there will be differences between the specified heat treatment temperature and that which is actually achieved. There are a variety of weld consumables available that have been designed for joining P92 steels; these consumables are heavily alloyed but have ranges over which the compositions of each element in the consumable are allowed to vary. While reaustenitisation of P92 base metals during post-weld heat treatment in the normal temperature range is not likely, it is known that weld metals have much lower A1 temperatures than parent metals. As such, concerns have been raised that, although weld consumables may exist w...

The hip is considered to be one of the main load bearing joints of the body. In the haemophilic patient joint bleeds can be catastrophic, leading to long-term joint degeneration and accompanying arthritis. In this review we explore the mechanisms of joint destruction, with particular consideration of the anatomy of the hip and how it may influence disease progression. We also review current strategies for treatment including hip replacement in the haemophilic patient and describe our experiences as a unit. Finally we evaluate future prospects in the management of hip disease in haemophilia.

Summary. Pseudotumours are a rare complication of haemophilia. Surgery undertaken for pseudotumour on a lesion that is subsequently found to be malignant can be expected to adversely affect patient outcome. We present six case reports found from a literature search of patients with haemophilia who underwent surgery on what was a primary malignancy misdiagnosed as a pseudotumour and give a subsequent discussion.

Spinal burst fractures account for about 15% of spinal injuries and, because of their predominance in the younger population, there are large associated social and healthcare costs. Although several experimental studies have investigated the burst fracture process, little work has been undertaken using computational methods. The aim of this study was to develop a finite element model of the fracture process and, in combination with experimental data, gain a better understanding of the fracture event and mechanism of injury. Experimental tests were undertaken to simulate the burst fracture process in a bovine spine model. After impact, each specimen was dissected and the severity of fracture assessed. Two of the specimens tested at the highest impact rate were also dynamically filmed during the impact. A finite element model, based on CT data of an experimental specimen, was constructed and appropriate high strain rate material properties assigned to each component. Dynamic validation was undertaken by comparison with high-speed video data of an experimental impact. The model was used to determine the mechanism of fracture and the postfracture impact of the bony fragment onto the spinal cord. The dissection of the experimental specimens showed burst fractures of increasing severity with increasing impact energy. The finite element model demonstrated that a high tensile strain region was generated in the posterior of the vertebral body due to the interaction of the articular processes. The region of highest strain corresponded well with the experimental specimens. A second simulation was used to analyse the fragment projection into the spinal canal following fracture. The results showed that the posterior longitudinal ligament became stretched and at higher energies the spinal cord and the dura mater were compressed by the fragment. These structures deformed to a maximum level before forcing the fragment back towards the vertebral body. The final position of the fragment did not therefore represent the maximum dynamic canal occlusion.

Advanced design requirements have dictated a need for the mechanical properties of materials at high strain rates. Mechanical testing for these data poses a significant problem for experimentalists. High-speed testing machines have a limited capability at rates approaching 102/s. The split Hopkinson pressure bar is the most reliable alternative for rates approaching 104/s. Plate impact experiments are capable of generating strain rates of 108/s and higher. The Taylor impact test occupies a place of particular importance by providing data at strain rates on the order of 104/s–105/s. The issue at present is extracting the data. This paper provides a method for obtaining dynamic strength model material constants from a single Taylor impact test. A polynomial response surface is used to describe the volume difference (error) between the deformed specimen from the Taylor test and the results of a computer simulation. The volume difference can be minimized using an optimizer, with the result being an optimum set of material constants. This method was applied to the modified Johnson-Cook model for OFHC copper. Starting from a nominal set of material constants, the iterative process improved the relative volume difference from 23.1 percent to 4.5 percent. Other starting points were used that yielded similar results. The material constants were validated by comparing numerical results with Taylor tests of cylinders having varying aspect ratios, calibers and impact velocities.

Bean common mosaic necrosis virus (BCMNV) was isolated from Centrosema pubescens, Crotalaria incana, Lablab purpureus, Phaseolus lunatus, Senna bicapsularis, S. sophera, Vigna vexillata and an unidentified Crotalaria species growing in Uganda. Thirteen distinct isolates were characterized using symptoms, pathogenicity in differential bean cultivars, serology, immunosorbent electron microscopy, and seed and aphid transmission. Some isolates conformed with the characteristics of previously described strains of BCMNV but others showed novel properties. All isolates reinfected the natural host from which they were obtained. The origin and ecological significance of these isolates is discussed.

Isolates of Pseudomonas syringae pv. phaseolicola from Africa and other bean growing areas were categorized into nine races on the basis of their reactions to eight differential cultivars following artificial inoculation. Eight hundred and ninety-three isolates representing 303 disease occurrences were initially identified as P.s. pv. phaseolicola by their pathogenicity to bean, cultural and serological characteristics and phage sensitivity. These tests also served to distinguish P.s. pv. phaseolicola from the closely related pathovars P.s. pv. glycinea and P.s. pv. syringae. Detailed race determinations were carried out on 175 selected isolates of p.s. pv. phaseolicola representative of the different geographical regions and hosts in which the pathogen was found and nine races were identified. A number of races (1,2,5,6 and 7) were distributed worldwide with race 6 predominant. Other races were found mainly in Africa; races 3 and 4 in East/Central Africa and races 8 and 9 in Southern Africa. Most isolates were obtained from the major host, Phaseolus vulgaris. Alternative natural hosts included 10 legume species representative of seven different genera (Cajanus cajan, Desmodium sp., Lablab purpureus, Macroptilium atropurpureum, Neonotonia wightii, Phaseolus acutifolius, P. coccineus, P. lunatus, Vigna angularis and V. radiata). Of these, Desmodium sp. constitutes a new host record.

OBJECTIVE Urine cytology is costly because of the skilled manpower required for analysis. Inappropriate requests are a significant drain both financially and on the cytopathologist's time. The present study aimed at identifying the extent and cause of this misuse and reduce it. METHODS An audit of urine cytology usage was undertaken using the hospital results reporting system to identify requests. Patient case notes were then obtained to gain further clinical information. Initially a 2-week period was analysed, following which departmental guidelines for requesting urine cytology were produced and circulated. The audit loop was then closed. RESULTS Over the initial 2-week period, 117 urine cytology requests were received. Thirty-three per cent were inappropriate, either because they were from patients with benign disease or because of duplication. Following the education programme this number fell to 6%. Expenditure on unnecessary samples thus decreased from pounds 2418 to only pounds 310, giving an annual overall saving of pounds 55,000. CONCLUSION Significant cost and time savings can be made if urine cytology is sent appropriately. Simple guidelines and staff education are the key to reducing inefficiency. Our findings have implications not just for cytopathology costs but for laboratory and radiology requests in general.

An enantiomeric assay for the flavonoids vestitone and medicarpin from transgenic plant extracts was developed using capillary electrophoresis. It was found that no single cyclodextrin proved capable of resolving the enantiomers of both medicarpin and vestitone. Instead, hydroxypropyl-beta-cyclodextrin provided the best selectivity for the vestitones while hydroxypropyl-gamma-cyclodextrin was best for the medicarpins. The addition of organic modifiers improved the resolution of both enantiomers. Acetonitrile proved best for the vestitones and only methanol improved the resolution of the medicarpins. An optimization study of mixed hydroxypropyl-beta-cyclodextrin and hydroxypropyl-gamma-cyclodextrin containing electrolytes revealed that the separation of the medicarpin enantiomers was intolerant to the presence of hydroxypropyl-beta-cyclodextrin. Our optimized running electrolyte was composed of 2 mM hydroxypropyl-beta-cyclodextrin, 20 mM hydroxypropyl-gamma-cyclodextrin, and 25 mM borate at pH 10.0 with 10% v/v methanol. This system provided a resolution of 1.47 and 1.80 for the medicarpin and vestitone enantiomers, respectively. This analysis was completed in 12 min. This separation provided a rapid screen to determine the enantiomeric purity of key flavonoids biosynthesized by transgenic legumes.

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In this study, we investigated a novel series of micelle modifiers useful to alter selectivity in micellar electrokinetic capillary chromatography (MEKC). These modifiers were alkyl polyalcohols, including 1-octanol, 1,2-octanediol, 1,2,3-octanetriol, 1,2-hexanediol, and 1,2-butanediol, which act as class I organic modifiers in that their effects are on the sodium dodecyl sulfate (SDS) micelle rather than the surrounding aqueous phase. This characteristic allows the alkyl polyols to effect resolution when applied at concentrations as low as 20 mM (0.25% v/v) by altering the selectivity observed with SDS without a modifier. The effects of the alkyl polyols on the critical micelle concentration of SDS, electroosmotic flow, and electrophoretic mobility of the SDS micelle are presented. These modifiers had little impact on the migration time window at the concentrations explored. Changes in selectivity induced by the alkyl polyols for a large set of model compounds are presented. Trends indicate that solutes capable of forming hydrogen bonds tend to decrease their interactions with the micellar phase while nonhydrogen bonding solutes increase their interactions upon addition of the modifiers. The solvation parameter model was used to characterize the induced changes in selectivity. This model suggests that even though the modifiers are structurally similar, each produced a unique set of system constants. It was also demonstrated that the addition of alkyl polyols improved the correlation between the partition coefficients of SDS and water to 1-octanol and water. The usefulness of the alkyl polyols was demonstrated by examining their effects on the separation of 11 priority phenols.

In this report, we introduce a new micelle modifier useful to alter selectivity in micellar electrokinetic capillary chromatography (MECC). 1,2-Hexanediol acts as a class I organic modifier in that its effects are on the sodium dodecyl sulfate (SDS) micellar rather than the surrounding aqueous phase. This characteristic allows 1,2-hexanediol to improve resolution when applied at concentrations as low as 20 mM (0.25% v/v) by altering the selectivity observed with SDS alone. The effects of 1,2-hexanediol on the critical micelle concentration of SDS, electroosmotic flow, electrophoretic mobility of the SDS micelle, and reproducibility are presented. 1,2-Hexanediol had little impact on the migration time window at concentrations below 100 mM. Changes in selectivity induced by 1,2-hexanediol for a large set of model compounds are presented. Analytes capable of forming hydrogen bonds tend to decrease their interactions with the micellar phase while nonhydrogen bonding analytes increase their interactions. The usefulness of 1,2-hexanediol was demonstrated by examining its effects on the separation of dansylated amino acids. Eighteen of twenty amino acids could be separated with a resolution greater than 1.6 within 1600 s using a combination of 1,2-hexanediol and isopropanol.

The use of 3-D assimilation model-derived dynamics in transport-chemistry models is a relatively new research methodology that has been used to interpret aircraft, ground-based remote sensing, balloon, and satellite data for the stratosphere. The unique aspect of these studies is that since the output of the assimilation procedure is a statistically optimal representation of dynamics, the time-varying output from this type of transport-chemistry model may be compared with sequences of actual observations. Some applications of this technique are presented relating to LIMS observations of nitric acid; the relation of satellite observed fields to model results; studies of the stratospheric ozone budget; and study of polar processing in relation to UARS CIO data.

The application of laser irradiation to etch dental enamel in preparation for direct bonding of orthodontic appliances has been studied. Forty extracted human teeth were divided into four groups of 10 teeth. Within each group, five teeth were subjected to a 30 sec acid etch of the buccal enamel surface; the other five in each group were etched with a laser. Four power settings on the laser etching unit were used: 80mJ, 1W, 2W and 3W. After etching, brackets were adhered to the prepared buccal enamel surfaces with composite resin. Shear bond strength was tested 7 days later. The findings showed that an acceptable shear bond strength, viz.or = 0.6 kg/mm, could be achieved at laser power settings of 1 to 3W but not at the lowest setting (80 mJ). However, the mean shear bond strengths obtained with laser treatment of the enamel at 80mJ, 1W and 2W were lower (p0.01 or 0.001) than that achieved with acid etching.

The heat produced at the dentinal pulpal wall opposite the irradiation site was measured during etching of dental enamel with an Nd:YAG laser in preparation for direct bonding of orthodontic appliances. Forty extracted human teeth were randomly divided into four groups of 10 teeth. Within each group, the buccal surfaces of 5 teeth and the lingual surfaces of the other 5 teeth were laser treated for 12 sec. Irradiation was performed with a commercial Nd:YAG laser at the power settings of 80mJ, 1W, 2W and 3W. Prior to irradiation, an occlusal access preparation was made into the pulp in order to facilitate the placement of a thermocouple for measurement of temperature changes at the dentinal pulpal wall opposite the irradiation site. The thermocouple was held against the dentinal pulpal wall and the resulting temperature changes were recorded. Heating effects at the dentinal pulpal wall on both buccal and lingual surfaces showed an increase in heat as a function of the increase in power output from the laser unit (p0.01). The temperatures measured at power levels 1-3W appeared to be of sufficient magnitude to cause at least localized pulpal inflammation and possible irreversible damage to the pulp tissue immediately opposite the site of laser irradiation.

SUMMARY Seasonal periodicity in the incidence of cowpea golden mosaic (CGM) and lima bean golden mosaic (LBGM), two whitefly-spread virus-like diseases, corresponded closely with fluctuations in population density of their vector, Bemisia tabaci, at two contrasting sites in southern Nigeria. Peak catches of the vector followed the onset of rains after very high temperatures during the dry season; populations declined abruptly with continuous, heavy rainfall. At Onne, B. tabaci infested legumes at emergence and remained and reproduced on them but at Ibadan infestation was delayed and there was no evidence of reproduction on legumes. B. tabaci preferred LBGM-susceptible lima beans (Phaseolus lunatus) to resistant ones and more pupae of B. tabaci occurred on CGM-susceptible cowpea (Vigna unguiculata) cultivars than on resistant ones but these observations did not relate to the yellow-sensitivity of whiteflies. Resistance to CGM in cowpea, and to LBGM in lima bean, was identified amongst germplasm exposed to natural infection. Resistance was, in each case, associated with lower disease incidence, slower spread and milder expression of symptoms relative to susceptible cultivars. Vector non-preference for resistant cultivars may have contributed to reduced secondary spread.

Metallographic and fractographic studies were undertaken to investigate weld metal microcracking in a 2·25Cr–1 M o steel fabrication. Numerous small microcracks were found in single-pass TIG welds in the as-welded condition. An unusual form of brittle fracture on prior austenite grain boundaries was observed, associated with a dense array of intergranular submicrometre sulphide inclusions. The observations indicated that sulphide precipitation had occurred by a solidstate mechanism as the weld metal cooled through the austenite range, while elemental sulphur segregation promoted grain-boundary faceting and embrittlement. The microcracks appeared to have formed on the previously faceted and embrittled grain boundaries by a low-temperature quench cracking mechanism. The factors responsible for the severe sulphur segregation are reviewed, and the implications are discussed in the context of recent interest in the role of grain-boundary sulphides in weld stress relief cracking.

Scanning electron microscopy was used to study the pathogenic protozoan, Acanthamoeba culbertsoni , in the leptomeningeal subarachnoid space surrounding the spinal cord of the experimentally inoculated dog. Known to inhabit such areas as moist soils, stagnant waters, and sewage around the world, these protozoans have been identified as etiologic agents in numerous cases of meningoencephalitis. Infection occurs via a nasopharyngeal inoculation, through penetration of the olfactory mucosal epithelium and cribriform plate, into the subarachnoid space, whence it gains access to the central nervous system. Stock preparations of these amebae extracted directly from their culture medium for scanning microscopic study provided an index for their identification within the subarachnoid space and also permitted a heretofore unobserved survey of their pleomorphic surface features. From the observations of others, it had appeared that the ultimate portal of entry into the central nervous system involved some type of cytolytic process; however, this study illustrates an action of simple diapedesis in which the organisms seek a pathway of least resistance; namely, the naturally-occurring pial fenestrations.

The paper describes the therapeutic programme of the Young People's Unit, Macclesfield. Admission is based on a therapeutic contract agreed with the youngster and family. Data on the first 150 admission to the Unit are presented. The information was collected from all referring agencies and a sample of youngsters and parents after an average period of two years since discharge. Results were similar to those of other follow-up studies of discharges from adolescent units, i.e. 78 per cent of neurotic disorders, 53 per cent of mixed neurotic and conduct disorders and 47 per cent of conduct disorders showed improvement. There was a high incidence of recurrence of the most significant presenting symptom (72 per cent). Nevertheless, referrers and youngsters showed a positive attitude to the treatment experience. The possible relationship of this to the contract system is discussed. A longer period of stay was found to correlate positively with improvement in conduct disorders. There is a need for further research into what aspects of a treatment milieu produce significant and lasting changes in conduct disorders.

Leaf samples of black bryony (Tamus communis L.) from Devon, UK, showing various virus-like symptoms contained potyvirus-like particles (normal length c. 790 nm) and cytoplasmic cylindrical (pinwheel) inclusions. In immunoelectron microscopy, particles of most samples reacted with antiserum to dioscorea greenbanding mosaic virus, a potyvirus isolate from Dioscorea rotundata in Togo which is related to yam mosaic virus from the Ivory Coast. Potyvirus particles were not transmitted by sap or aphids (Myzuspersicae) from infected black bryony to black bryony seedlings or Nicotiana benthamiana. One sample from a symptomless plant of black bryony contained a potexvirus which formed massed virion aggregates in the cytoplasm of cells of black bryony, Nicotiana benthamiana and N. megalosiphon. Virions of the potexvirus (normal length 553 nm) contained a coat protein with an apparent molecular weight of 27.7 kd. The potexvirus differed from an Italian potexvirus isolate from black bryony by a serological differentiation index of 4 and gave only weak or no reactions with 23 other antisera to potexviruses, including dioscorea latent virus. The potexvirus caused systemic symptoms in only a few host plants and could be transmitted back to black bryony in which it caused no symptoms. It is provisionally named tamus latent virus.

When a fracture surface is exposed to high temperatures, its original features may be smoothed by surface diffusion, and new features such as thermal facets and grain-boundary grooves may form. Obs...

Diffusion in the liquid during the later stages of cellular and dendritic solidification is described. A simple model is constructed, incorporating adaptations of the earlier treatments by Bower, Brody, and Flemings1,2 and Rohatgi and Adams:3 the apparent conflict between these treatments is discussed. Behind the growth front, the diffusion fields of neighboring primary arms spread laterally, meet and merge in an initial transient. This can take up a significant fraction of the solidification time, especially at high growth rates. After the initial transient has been completed, the supercooling of the interdendritic liquid is reduced, but concentration gradients in the liquid persist throughout solidification.

Repeated thrombin treatment of washed platelets prepared from rabbits can decrease the serotonin content of the platelets by about 80%. When these platelets are deaggregated they reaccumulate serotonin but their storage capacity for serotonin is reduced by about 60%. If thrombin-pretreated platelets are allowed to equilibrate with a high concentration of serotonin (123 mu M), they release a smaller percentage of their total serotonin upon further thrombin treatment, in comparison with the percentage of serotonin released from control platelets equilibrated with the same concentration of serotonin calculations indicate that in thrombin-treated platelets reequilibrated with serotonin, two-thirds of the serotonin is in the granule compartment and one-third is in the extragranular compartment, presumably the cytoplasm. Analysis of the exchange of serotonin between the suspending fluid and the platelets showed that thrombin treatment does not alter the transport rate of serotonin across the platelet membrane and does not cause increased diffusion of serotonin from the platelets into the suspending fluid. The primary reason for the reduced serotonin accumulation by the thrombin-treated platelets appears to be loss of amine storage granules or of the storage capacity within the granules.

The observation of radiation-induced latch-up windows has caused doubt in the validity of accepted latch-up screens. Models giving a plausible explanation of latch-up windows are presented which show that they are only a special case of latch-up as explained by many investigators and can be treated accordingly. Furthermore, they are eliminated when latch-up is prevented by either neutron irradiation of the devices or utilization of epitaxial substrates.

An earlier paper described how the problem behaviours of adolescents who had experienced treatment at the Young People's Unit, Macclesfield changed. This paper describes the components of that experience, the clients' and referrers' evaluation of those components and their attitudes to the treatment received. The study occurred after an average post-discharge period of two years. A factor analysis produced two main clusters of attitudes relating to “personal growth” and “valuing of the unit experience”. Youngsters with positive attitudes towards the experience had significantly better outcomes. This finding is compared with a study of approved school boys. It is suggested that the components of the Young Peoples' Unit may be more suited to the maturational tasks of adolescence. The findings refute the justification that residential units have helped personal growth despite the continuation of problem behaviour. The study has implications for Health Service planning for disturbed adolescents and for community agencies' attitudes to the use of residential treatment.

Three digital mucous cysts and three dorsal wrist ganglia were studied by light and scanning electron microscopy. Both exhibited the same findings, namely a porous network of collagenous fibers forming the wall and a fibrillated inner surface composed of a random arrangement of collagen fibers. An intermittent thin membrane was observed on the inner surface, but no evidence of a cellular lining was apparent. This anatomic study lends support to a shared cause.

SUMMARY Adult whiteflies (Bemisia tabaci) acquired the agent of cowpea golden mosaic (CGM-A) within 7 min and transmitted during 2 min inoculation access. Nymphs also acquired CGM-A and retained it through the pupal stage. Efficiency of transmission reached 90% when the acquisition period was increased to 36 h. The minimum latent period of CGM-A in B. tabaci was 8 h, and the median latent period (LP50) about 12 h. Transmission was generally intermittent and declined throughout the period of 21 days which was the maximum time insects remained infective. Female whiteflies were more efficient vectors than males. B. tabaci acquired CGM-A from plants inoculated only 60 h previously. The epidemiological implications of these findings are discussed.

Metallographic studies of weld solidification in the submerged-arc strip-Cladding process are described. It is shown that different solidification sequences took place in different parts of the same weld bead. The primary or leading phase was austenite in the lower part of the bead, but δ-ferrite in the upper regions, while in the central area of the head austenite and δ-ferrite grew simultaneously as primary phases. This unexpectedly complex behaviour is discussed in the context of recent It work on the solidification of austenitic steel welds, It with reference to effects on solidification cracking and ultrasonic inspection.

We used a laboratory model of gouty synovitis giving quantitative dose-dependent results with urate injection intrasynovially into the knee joint of dogs. We found that when precautions were taken to prevent any possible endotoxin contamination of the urate crystals, they became significantly less active. Endotoxin by itself, from Escherichia coli, was very potent in causing pain and leukocytic infiltration into the knee joint. Such endotoxin was readily and firmly adsorbed onto urate crystals. A small dose of urate crystals that caused no pain by itself became very painful when the crystals were allowed to adsorb endotoxin in vitro. When this same small non-painful dose of urate crystals was given into the joint, and the dog also received endotoxin by the oral route, signs of pain arose very clearly. It is known that gouty patients even when in remission may have crystals of sodium urate in the synovial fluid. It would therefore appear possible that if such urate crystals were to adsorb an endotoxin passing from the gastrointestinal tract into the plasma, thence into the synovial space, the patients may develop an attack of gout.

SUMMARY Cultivars of cowpea (Vigna unguiculata) possessing tolerance to infection by cowpea mottle virus (CMeV) under screenhouse conditions exhibited both tolerance and resistance to infection by beetle vectors under field conditions. Resistance to infection was exemplified by delayed and reduced incidence of infection resulting from natural infection pressure, and appeared to be unrelated to vector feeding preference. This suggests that certain cowpea cultivars such as TVu 3901 possess more than one component of resistance (sensu Russell, 1978) to CMeV. Despite some correspondence between results from artificial (mechanical) and natural (vector) inoculation, we suggest that field evaluation is often an important adjunct to greenhouse screening for virus disease resistance since resistance mechanisms operative under field conditions may be overlooked in artificial screening programmes. In the susceptible cultivar TVu 612, when artificially inoculated, CMeV is transmissible through cowpea seed up to 0.4%. In only one instance was CMeV seed transmitted from natural infection. We suggest that apparent inefficiency in seed transmission may in part account for the restricted ecological and geographical distribution of CMeV.

While the effects of welding parameters on the shapes of single weld beads have been extensively studied, less is known about how bead shape and penetration alter in multipass welding. In this paper are described studies on the shapes of overlapping beads in manual metal arc cladding of ferritic steel by austenitic stainless steel. Different deposition techniques were used to vary bead positioning and the degree of overlap, and the effects on bead height, width, penetration, and dilution were determined. It is shown that various changes in these parameters occur when weld beads are overlapped. The most important effect is a reduction in penetration and dilution, which is especially marked when the position of arc impingement is on the previous weld bead rather than the base plate. The implications for ultrasonic inspection of clad components, and for weld modelling, are discussed.

The evaluation of greenhouse and field screening methods for the identification of resistance to bacterial blight (Xanthomonas vignicola Burkh.) amongst germplasm and breeding lines of cowpea (Vigna unguiculata(L.) Walp.) is described. A stem injection technique and a leaf infiltration method were found reliable under greenhouse conditions while foliar spray inoculation was appropriate for use in both greenhouse and field experiments. A seed inoculation technique for evaluating seedling mortality may prove useful although only one susceptible cowpea accession was used in this study. Since distinct syndromes of bacterial blight (seedling mortality, stem canker and foliar blight) are recognised, it may be advantageous to adopt a different inoculation method for each syndrome to establish the relationship between the resistance of different plant parts within cowpea genotypes. Results confirm the existence of at least two distinct mechanisms of resistance to bacterial blight in cowpea. Hypersensitiv...

A significant portion of the demand for industrial process heat can be met with solar energy. Whether this energy source is widely used will depend not only on its economic attractiveness, but also on the ease with which solar thermal systems interface with the remainder of the industrial plant. Foster Wheeler has recently designed solar thermal systems to supply hot water and process steam to industry and has nearly completed the construction of one of these. Drawing on this experience, this paper discusses selection of solar technologies that can best satisfy the user’s energy requirements and minimize interfacing problems.