Vetting of medical imaging referrals: A scoping review of the radiographers' role.

INTRODUCTION: Vetting and treatment verification, are now an expectation of threshold radiography competencies at qualification. Radiographer-led vetting contributes to the expedition of patients' treatment and management. However, the current state and the role of the radiographer in vetting medical imaging referrals remains unclear. This review aims to explore the current state and associated challenges to a radiographer-led vetting and offer directions for future research by addressing knowledge gaps. METHOD: The Arksey and O'Malley methodological framework was employed for this review. This includes a comprehensive search using key terms relating to radiographer-led vetting across relevant databases: Medline, PubMed, AMED and Cumulative Index to Nursing and Allied Health Literature (CINAHL). Articles were screened for eligibility and information extracted and analysed descriptively to map the available evidence. RESULTS: 1149 studies were identified with 12 articles included for this review after duplicates were removed. The findings indicate existence of some radiographer-led vetting activities in practice; however, the scope of this practice is associated with a large variance across settings. Key challenges relating to radiographer-led vetting include referral selectivity, medical professional dominance, and lack of clinical indication on referrals. CONCLUSION: Radiographers vet various categories of referrals depending on jurisdictional policies and more clarity in regulation, advanced practice training and change in workplace culture is needed to support radiographer-led vetting. IMPLICATION FOR PRACTICE: Radiographer-led vetting should be championed across settings through formalised training to widen the scope of advance practice and career progression pathways for radiographers as a means of ensuring optimal use of resources.

Short-wavelength free-electron laser sources and science: a review.

This review is focused on free-electron lasers (FELs) in the hard to soft x-ray regime. The aim is to provide newcomers to the area with insights into: the basic physics of FELs, the qualities of the radiation they produce, the challenges of transmitting that radiation to end users and the diversity of current scientific applications. Initial consideration is given to FEL theory in order to provide the foundation for discussion of FEL output properties and the technical challenges of short-wavelength FELs. This is followed by an overview of existing x-ray FEL facilities, future facilities and FEL frontiers. To provide a context for information in the above sections, a detailed comparison of the photon pulse characteristics of FEL sources with those of other sources of high brightness x-rays is made. A brief summary of FEL beamline design and photon diagnostics then precedes an overview of FEL scientific applications. Recent highlights are covered in sections on structural biology, atomic and molecular physics, photochemistry, non-linear spectroscopy, shock physics, solid density plasmas. A short industrial perspective is also included to emphasise potential in this area.

Novel insights into early neuroanatomical evolution in penguins from the oldest described penguin brain endocast.

Digital methodologies for rendering the gross morphology of the brain from X-ray computed tomography data have expanded our current understanding of the origin and evolution of avian neuroanatomy and provided new perspectives on the cognition and behavior of birds in deep time. However, fossil skulls germane to extracting digital endocasts from early stem members of extant avian lineages remain exceptionally rare. Data from early-diverging species of major avian subclades provide key information on ancestral morphologies in Aves and shifts in gross neuroanatomical structure that have occurred within those groups. Here we describe data on the gross morphology of the brain from a mid-to-late Paleocene penguin fossil from New Zealand. This most basal and geochronologically earliest-described endocast from the penguin clade indicates that described neuroanatomical features of early stem penguins, such as lower telencephalic lateral expansion, a relatively wider cerebellum, and lack of cerebellar folding, were present far earlier in penguin history than previously inferred. Limited dorsal expansion of the wulst in the new fossil is a feature seen in outgroup waterbird taxa such as Gaviidae (Loons) and diving Procellariiformes (Shearwaters, Diving Petrels, and allies), indicating that loss of flight may not drastically affect neuroanatomy in diving taxa. Wulst enlargement in the penguin lineage is first seen in the late Eocene, at least 25 million years after loss of flight and cooption of the flight stroke for aquatic diving. Similar to the origin of avian flight, major shifts in gross brain morphology follow, but do not appear to evolve quickly after, acquisition of a novel locomotor mode. Enlargement of the wulst shows a complex pattern across waterbirds, and may be linked to sensory modifications related to prey choice and foraging strategy.

Demonstration of a high-field short-period superconducting helical undulator suitable for future TeV-scale linear collider positron sources.

The first demonstration of a full-scale working undulator module suitable for future TeV-scale positron-electron linear collider positron sources is presented. Generating sufficient positrons is an important challenge for these colliders, and using polarized e(+) would enhance the machine's capabilities. In an undulator-based source polarized positrons are generated in a metallic target via pair production initiated by circularly polarized photons produced in a helical undulator. We show how the undulator design is developed by considering impedance effects on the electron beam, modeling and constructing short prototypes before the successful fabrication, and testing of a final module.

Using membrane stress to our advantage.

The nature of the bilayer motif coupled with the ability of lipids and proteins to diffuse freely through this structure is crucial to the viability of cells and their ability to compartmentalize domains contained therein. It seems surprising to find then that biological as well as model membranes exist in a dynamic state of mechanical stress. The stresses within such membranes are surprisingly large, typically reaching up to 50 atm (1 atm=101.325 kPa) at the core of the membrane and vary as a function of depth. The uneven distribution of lateral pressures within monolayer leaflets causes them to bend away from or towards the water interface. This can result in the formation of complex, self-assembled mesophases, many of which occur in vivo. Our knowledge of the principles underlying membrane mechanics has reached the point where we are now able to manipulate them and create nano-structures with reasonable predictability. In addition, they can be used both to explain and control the partitioning of amphipathic proteins on to membranes. The dependence of the dynamics of membrane-bound proteins and the chemical reactivity of amphipathic drug molecules on membrane stresses suggests that Nature itself takes advantage of this. Understanding and manipulating these internal forces will be a key element in creating self-assembled, biocompatible, nanoscale cell-like systems.

Traction for low-back pain with or without sciatica.

BACKGROUND: Traction is used to treat low-back pain (LBP), often with other treatments. OBJECTIVES: To determine traction's effectiveness, compared to reference treatments, placebo, sham traction or no treatment for LBP. SEARCH STRATEGY: We searched CENTRAL (The Cochrane Library 2006, issue 4), MEDLINE, EMBASE, and CINAHL to October 2006, references in relevant reviews and personal files. SELECTION CRITERIA: Randomized controlled trials (RCTs) involving traction to treat acute (less than four weeks duration), sub-acute (four to 12 weeks) or chronic (more than 12 weeks) non-specific LBP with or without sciatica. DATA COLLECTION AND ANALYSIS: Study selection, methodological quality assessment and data extraction were done independently by two authors. As there were insufficient data for statistical pooling, we performed a qualitative analysis. MAIN RESULTS: We included 25 RCTs (2206 patients; 1045 receiving traction). Five trials were considered high quality. For patients with mixed symptom patterns (acute, sub-acute and chronic LBP with and without sciatica) there is: strong evidence of no statistically significant difference in outcomes between traction as a single treatment and placebo, sham or no treatment; moderate evidence that traction as a single treatment is no more effective than other treatments; limited evidence of no significant difference in outcomes between a standard physical therapy program with or without continuous traction. For LBP patients with sciatica (with acute, sub-acute or chronic pain), there is conflicting evidence in several comparisons: autotraction compared to placebo, sham or no treatment; other forms of traction compared to other treatments; different forms of traction. In other comparisons, there were no statistically significant differences; the evidence is moderate for continuous or intermittent traction compared to placebo, sham or no treatment, and limited for light versus normal force traction. IMPLICATIONS FOR PRACTICE: The results of the available studies involving mixed groups of acute, sub-acute and chronic patients with LBP with and without sciatica were quite consistent, indicating that continuous or intermittent traction as a single treatment for LBP is not likely effective for this group. Traction for patients with sciatica cannot be judged effective at present either, due to inconsistent results and methodological problems in most studies. We conclude that traction as a single treatment for LBP is probably not effective. IMPLICATIONS FOR RESEARCH: Any future research on traction for patients with LBP should distinguish between symptom pattern and duration, and should be carried out according to the highest methodological standards.

Traction for low-back pain with or without sciatica.

BACKGROUND: Various types of traction are used in the treatment of low-back pain (LBP), often in conjunction with other treatments. OBJECTIVES: To determine the effectiveness of traction in the management of LBP. SEARCH STRATEGY: We searched The Cochrane Library 2004, Issue 4, MEDLINE, EMBASE, and CINAHL to November 2004, references in relevant reviews, and our personal files. SELECTION CRITERIA: Randomized controlled trials (RCTs) examining any type of traction for the treatment of acute (less than four weeks duration), sub-acute (four to 12 weeks) or chronic (more than 12 weeks) non-specific LBP with or without sciatica. DATA COLLECTION AND ANALYSIS: Study selection, methodological quality assessment and data extraction were done independently by sets of two reviewers. As available studies did not provide sufficient data for statistical pooling, a qualitative analysis was performed. MAIN RESULTS: Twenty-four RCTs, involving 2177 patients (1016 receiving traction) were included in the review. Five trials were considered high quality. There is strong evidence that there is no significant difference in short or long-term outcomes between either continuous or intermittent traction and placebo, sham, or other treatments for patients with a mixed duration of LBP, with or without sciatica. There is moderate evidence that: autotraction is more effective other forms of traction are no more effective than placebo, sham or no treatment for patients with a mixed duration of LBP with sciatica. There is limited evidence that: there is no significant difference in outcomes between a standard physical therapy program with continuous traction and the same program without traction, for patients with a mixed duration of LBP, with or without sciatica autotraction on its own is more effective than a physical therapy program that includes Tru-Trac traction for patients with a mixed duration of LBP with sciatica. There is conflicting evidence regarding the short-term effectiveness of either continuous or intermittent traction compared to placebo, sham or other treatments, in the management of patients who have either chronic LBP or a mixed duration of LBP with sciatica. AUTHORS' CONCLUSIONS: The evidence suggests that traction is probably not effective. Neither continuous nor intermittent traction by itself was more effective in improving pain, disability or work absence than placebo, sham or other treatments for patients with a mixed duration of LBP, with or without sciatica. Although trials studying patients with sciatica had methodological limitations and inconsistent results, there was moderate evidence that autotraction was more effective than mechanical traction for global improvement in this population.

A reappraisal of the role of cerium in burn wound management.

A rare earth element, cerium, was introduced as an antibacterial agent in 1976 but has rarely been used due to the emphasis on wound excision. Used in combination with silver sulphadiazine, it may improve patient survival when excision is not possible.

The distribution of presumptive thoracic paraganglionic tissue in the common marmoset (Callithrix jacchus).

The aortic-pulmonary regions (APR) of seven adult marmosets (Callithrix jacchus) and the region of the right subclavian artery of a further three marmosets were diffusion-fixed with 10% buffered formol-saline solution. In both regions serial 5 microm sections were cut and stained by the Martius yellow, brilliant crystal scarlet and soluble blue method. Presumptive thoracic paraganglionic (PTP) tissue was only observed in the APR. PTP tissue was composed of small groups of cells that varied in size and number. The distribution of the groups of cells was extremely variable, so much so that it would be misleading to attempt to classify their position; they were not circumscribed by a connective tissue capsule, but were always related to the thoracic branches of the left vagus nerve. The cells lay in loose areolar tissue characteristic of this part of the mediastinum and received their blood supply from small adjacent connective tissue arterioles. Unlike the paraganglionic tissue found in the carotid body the cells in the thorax did not appear to have a profuse capillary blood supply. There was, however, a close cellular-neural relationship. The cells, 10-15 microm in diameter, were oval or rounded in appearance and possessed a central nucleus and clear cytoplasm. No evidence was found that these cells possessed a 'companion' cell reminiscent of the arrangement of type 1 and type 2 cells in the carotid body. In conclusion, we found evidence of presumed paraganglionic tissue in the APR of the marmoset which, however, did not show the characteristic histological features of the aortic body chemoreceptors that have been described in some non-primate mammals. A survey of the mediastina of other non-human primates is required to establish whether this finding is atypical for these animals.

The distribution of presumptive thoracic paraganglionic tissue in the common marmoset (Callithrix jacchus)

The aortic-pulmonary regions (APR) of seven adult marmosets (Callithrix jacchus) and the region of the right subclavian artery of a further three marmosets were diffusion-fixed with 10 percent buffered formol-saline solution. In both regions serial 5-æm sections were cut and stained by the Martius yellow, brilliant crystal scarlet and soluble blue method. Presumptive thoracic paraganglionic (PTP) tissue was only observed in the APR. PTP tissue was composed of small groups of cells that varied in size and number. The distribution of the groups of cells was extremely variable, so much so that it would be misleading to attempt to classify their position; they were not circumscribed by a connective tissue capsule, but were always related to the thoracic branches of the left vagus nerve. The cells lay in loose areolar tissue characteristic of this part of the mediastinum and received their blood supply from small adjacent connective tissue arterioles. Unlike the paraganglionic tissue found in the carotid body the cells in the thorax did not appear to have a profuse capillary blood supply. There was, however, a close cellular-neural relationship. The cells, 10-15 æm in diameter, were oval or rounded in appearance and possessed a central nucleus and clear cytoplasm. No evidence was found that these cells possessed a 'companion' cell reminiscent of the arrangement of type 1 and type 2 cells in the carotid body. In conclusion, we found evidence of presumed paraganglionic tissue in the APR of the marmoset which, however, did not show the characteristic histological features of the aortic body chemoreceptors that have been described in some non-primate mammals. A survey of the mediastina of other non-human primates is required to establish whether this finding is atypical for these animals

Contrast echocardiography for detection of pulmonary arteriovenous malformations.

BACKGROUND: Pulmonary arteriovenous malformations (PAVMs) lead to stroke, brain abscess, and hemorrhage in hereditary hemorrhagic telangiectasia (HHT). The current screening approach for PAVMs in HHT patients with chest radiograph (CXR) and oxygen shunt study has not been validated and is thought to be insensitive. We hypothesized that agitated saline contrast echocardiography (ECHO) would be a useful screening test for PAVMs. METHODS AND RESULTS: A total of 106 sequential HHT patients underwent screening for PAVMs with ECHO in a prospective study. If the test was positive, or if the CXR or shunt study suggested PAVMs, pulmonary angiography was performed. A positive ECHO was defined as appearance of bubbles in the left atrium after injection of agitated saline solution. A positive shunt study was defined as a partial pressure of oxygen in arterial blood <500 mm Hg while breathing 100% oxygen. The mean age was 41 years (range 15-80 years); 66% were female. Forty-four patients had positive ECHO. Forty-one of the 44 patients underwent angiography. Three patients declined further testing. Thirty-three of the 41 patients who underwent angiography were diagnosed with PAVMs. Of the 62 patients with a negative ECHO, 18 underwent angiography because of either a shunt study or CXR that was suggestive of PAVMs. Of these 18 patients, 2 had PAVMs. In the total population of 106 patients, 35 (33%) had PAVMs. ECHO was the only positive screening test in 11 of 35 (31%) patients. The diagnosis of PAVMs in these 11 patients would have otherwise been missed. CONCLUSIONS: ECHO is a useful screening tool for PAVMs in HHT.

Fossil that fills a critical gap in avian evolution.

Despite the discoveries of well-preserved Mesozoic birds, a key part of avian evolution, close to the radiation of all living birds (Aves), remains poorly represented. Here we report on a new taxon from the Late Cretaceous locality of Ukhaa Tolgod, Mongolia, that offers insight into this critically unsampled period. Apsaravis and the controversial alvarezsaurids are the only avialan taxa known from the continental deposits at Ukhaa Tolgod, which have produced hundreds of fossil mammals, lizards and other small dinosaurs. The new taxon, Apsaravis ukhaana, is the best-preserved specimen of a Mesozoic ornithurine bird discovered in over a century. It provides data important for assessing morphological evolution across Avialae, with implications for, first, the monophyly of Enantiornithes and Sauriurae; second, the proposition that the Mesozoic sister taxa of extant birds, as part of an 'ecological bottleneck', inhabited exclusively near-shore and marine environments; and third, the evolution of flight after its origin.

Assessment of adherence to renal dosing guidelines in long-term care facilities.

OBJECTIVE: We determined whether dosing guidelines based on creatinine clearance (Ccr) for renally excreted drugs are being applied when prescribing to long-term care residents DESIGN: A cross sectional chart review for the month of May 1999. PARTICIPANTS: Long-term care residents more than 65 years of age from four long-term care facilities in Southern Ontario who were prescribed a medication from a list of renally excreted drugs commonly prescribed in long-term care facilities. RESULTS: Approximately one in three prescriptions (34.1%) were considered inappropriate for the calculated Ccr of the residents. Overall, 42.3% of the residents who were prescribed a drug under review received at least one inappropriate prescription based on creatinine clearance. Logistic regression found that age (odds ratio (OR) = 1.06 per year; 95% confidence interval (CI) 1.03-1.09, P = .001), weight (OR = 0.96 per kg; 95% CI 0.94-0.98, P < .001), the total number of prescribed medications (OR = 1.10; 95% CI 1.04-1.17, P = .001), and the number of physicians prescribing in the facility (OR 1.02; 95% CI, 1.003-1.044, P = .03) were predictive for receiving an inappropriate prescription based on Ccr. CONCLUSIONS: Renal function is often overlooked when prescribing renally excreted drugs to older long-term care residents. These findings emphasize the need for consideration of Ccr when prescribing such drugs in this population.

Pramipexole versus bromocriptine for levodopa-induced complications in Parkinson's disease.

OBJECTIVES: To compare the efficacy and safety of adjuvant pramipexole versus bromocriptine therapy in patients with Parkinson's disease, already established on levodopa and suffering from motor complications. SEARCH STRATEGY: Electronic searches of MEDLINE, EMBASE and the Cochrane Controlled Trials Register. Handsearching of the neurology literature as part of the Cochrane Movement Disorders Group's strategy. Examination of the reference lists of identified studies and other reviews. Contact with Pharmacia Upjohn and Boehringer Ingelheim. SELECTION CRITERIA: Randomised controlled trials of pramipexole versus bromocriptine in patients with a clinical diagnosis of idiopathic Parkinson's disease and long-term complications of levodopa therapy. DATA COLLECTION AND ANALYSIS: Data was abstracted independently by the authors and differences settled by discussion. The outcome measures used included Parkinson's disease rating scales, levodopa dosage, 'off' time measurements and the frequency of drop outs and adverse events. MAIN RESULTS: One randomised controlled trial has compared pramipexole with bromocriptine using a double-blind, parallel group, multicentre design. It was not powered to examine differences between active treatment arms. There was a larger reduction in off time with pramipexole therapy compared with bromocriptine (weighted mean difference 1.4 hours; 0, 2.8, 95% CI). No differences occurred in dyskinesia rating scale, dyskinesia as an adverse event or UPDRS complication score. The UPDRS ADL and motor scores showed similar improvements compared to placebo with both agonists. Levodopa dose reduction was similar with both agonists. Subscales of the Functional Status Questionnaire showed significant improvements compared to placebo with both agonists. The finding that the EuroQol improved significantly compared with placebo with pramipexole but not bromocriptine should be treated with caution. Dopaminergic adverse events were similar with each agonist, as was the all cause withdrawal rate. REVIEWER'S CONCLUSIONS: Although pramipexole and bromocriptine improved off time and reduced parkinsonian motor impairments and disability compared with placebo, no conclusions regarding their comparative effectiveness and safety can be drawn as this single trial did not have adequate power to assess such differences. Further larger trials are required to examine this issue in the future.

Pramipexole for levodopa-induced complications in Parkinson's disease.

OBJECTIVES: To compare the efficacy and safety of adjuvant pramipexole therapy versus inactive placebo in patients with Parkinson's disease, already established on levodopa. SEARCH STRATEGY: Electronic searches of MEDLINE, EMBASE and the Cochrane Controlled Trials Register. Handsearching of the neurology literature as part of the Cochrane Movement Disorders Group's strategy. Examination of the reference lists of identified studies and other reviews. Contact with Pharmacia Upjohn and Boehringer Ingelheim. SELECTION CRITERIA: Randomised controlled trials of pramipexole versus placebo in patients with a clinical diagnosis of idiopathic Parkinson's disease and long-term complications of levodopa therapy. DATA COLLECTION AND ANALYSIS: Data was abstracted independently by the authors and differences settled by discussion. The outcome measures used included Parkinson's disease rating scales, levodopa dosage, 'off' time measurements and the frequency of drop outs and adverse events. MAIN RESULTS: Four randomised controlled trials have compared pramipexole with placebo in 669 patients with later Parkinson's disease. Two phase III studies were medium term (24 weeks maintenance period) and 2 phase II studies were short term (4 weeks maintenance period). The reduction in off time was significantly greater with pramipexole compared with placebo (weighted mean difference 1.8 hours; 1.2, 2.3 95% CI). No significant changes were noted in a dyskinesia rating scale in any of the 4 studies, but dyskinesia as an adverse event was reported more frequently with pramipexole. A significant improvement occurred in UPDRS complication score (part IV) in 2 studies but not in the remaining trials. Statistically significant improvements in UPDRS ADL score occurred with pramipexole in all studies. Significant improvements in UPDRS motor scores in the on state were reported in 3 of the 4 studies. Levodopa dose reduction was allowed in 3 studies and meta-analysis shows a significant difference in favour of pramipexole (weighted mean difference 115 mg; 87, 143 95% CI). Trends toward a higher incidence of dopaminergic adverse events with pramipexole only reached statistical significance regarding hallucinations. There were significantly fewer withdrawals from pramipexole. REVIEWER'S CONCLUSIONS: Pramipexole can be used to reduce off time, improve motor impairments and disability and reduce levodopa dose at the expense of increased dyskinetic adverse events. This conclusion is based on short and medium term trials (up to 24 weeks). Further trials are required to directly compare the newer with the older dopamine agonists.

Quantitative studies of the vasculature of the carotid body in the chronically hypoxic rat.

The carotid bodies of rats made chronically hypoxic by breathing 12% O2 in a normobaric chamber (inspired PO2 91 mmHg) were compared with those of controls. Serial 5-microm sections of the organs were examined using an interactive image analysis system. The total volume of the carotid bodies was increased by 64%. The total vascular volume rose by 103% and was likely due to an increase in size of the large vessels (>12 microm lumen diameter) because the small vessel (5-12 microm lumen diameter) volume did not increase significantly while the small vessel density tended to decrease. The extravascular volume was increased by 57%. Expressed as a percentage of the total volume of the organ, the total vascular volume did not change, but the small vessel volume was significantly decreased from 7.83 to 6.06%. The large vessel volume must therefore have been increased. The proportion occupied by the extravascular volume was virtually unchanged (84 vs 82%). In accordance with these findings, the small vessel endothelial surface area per unit carotid body volume was diminished from 95.2 to 76.5 mm-1, while the extravascular area per small vessel was increased from 493 to 641 microm(2) or by 30%. In conclusion, the enlargement of the carotid body in chronic hypoxia is most likely due to an increase in total vascular volume, mainly involving the "large" vessels, and to an increase in extravascular volume. This is in contrast to our previously published findings indicating that in the spontaneous insulin-dependent diabetic rat the enlargement of the carotid body is due solely to an increase in extravascular volume.

Prediction of toxigenic fungal growth in buildings by using a novel modelling system.

There is growing concern about the adverse effects of fungal bioaerosols on the occupants of damp dwellings. Based on an extensive analysis of previously published data and on experiments carried out within this study, critical limits for the growth of the indoor fungi Eurotium herbariorum, Aspergillus versicolor, and Stachybotrys chartarum were mathematically described in terms of growth limit curves (isopleths) which define the minimum combination of temperature (T) and relative humidity (RH) at which growth will occur. Each growth limit curve was generated from a series of data points on a T-RH plot and mathematically fitted by using a third-order polynomial equation of the form RH = a(3)T(3) + a(2)T(2) + a(1)T + a(0). This fungal growth prediction model was incorporated within the ESP-r (Environmental Systems Performance [r stands for "research"]) computer-based program for transient simulation of the energy and environmental performance of buildings. For any specified location, the ESP-r system is able to predict the time series evolution of local surface temperature and relative humidity, taking explicit account of constructional moisture flow, moisture generation sources, and air movement. This allows the predicted local conditions to be superimposed directly onto fungal growth curves. The concentration of plotted points relative to the curves allows an assessment of the risk of fungal growth. The system's predictive capability was tested via laboratory experiments and by comparison with monitored data from a fungus-contaminated house.

The carotid body of the spontaneous insulin-dependent diabetic rat.

The carotid bodies from adult spontaneous insulin-dependent diabetic rats (strain BB/S) were perfusion-fixed at normal arterial blood pressure with 3% phosphate-buffered glutaraldehyde and compared with the organs from control rats (strain BB/Sc) prepared in the same way. Serial 5-micron sections were cut, stained, and using an interactive image analysis system, were analysed to determine the volumes of the carotid body and its vascular and extravascular compartments. There was no evidence of systemic arterial disease in the carotid stem arteries in either group of animals, and the microvasculature of the organs appeared normal by light microscopy. The volume of the carotid body was unchanged 3 months after the onset of diabetes but was increased at 6 months. The total vascular volume of the organ was unchanged, but the volume of the small vessels (5-12 microns) was increased. In the control group the small vessels comprised 5% of the total volume of the carotid body, or about 44% of the vascular compartment. The percentage of small vessels increased at 3 months in the diabetic group, but had returned to normal at 6 months. The extravascular volume followed the same pattern as the total carotid body volume and so did not change appreciably when expressed as a percentage of the total volume of the organ. The increase in size of the carotid body in diabetic rats is due, therefore, to an augmented extravascular volume. In one diabetic specimen the carotid sinus nerve showed signs of diabetic neuropathy, axonal swelling and intramyelinic oedema. The clinical implications of these results are discussed.

Design of a 2 T multipole wiggler insertion device for the SRS.

Two new identical insertion devices have been designed for the Daresbury SRS. They are 2 T permanent-magnet multipole wigglers that will provide high flux in the X-ray region. This paper describes the magnetic and mechanical design of the arrays of steel pole pieces and permanent-magnet blocks. Also given is the engineering design of the support structure that will cope with the very large forces present while maintaining high levels of precision in gap setting and parallelism. The engineering design has been fully assessed using finite-element techniques to predict the deflections of critical parts of the structure. These two devices are due to be installed into the SRS by the end of 1998.