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A rapid and feasible priority-setting method conducted within a limited budget was used to identify research topics that would have an influence on health services for older adults. Health and aging researchers, policy makers, and caregivers were recruited to complete Delphi surveys that generated and ranked topics and identified other potential researchers. An interdisciplinary team of researchers was selected to produce and submit a proposal to a peer-review-granting agency. This method can be adapted by organizations to determine the focus of their research agenda and to engage individuals for collaboration on future research projects.

Background: The histamine H3 receptor plays a critical role in the negative neuromodulation of neurotransmitters involved in cognitive function. H3 receptor antagonists/inverse agonists have been shown to exert pro-cognitive effects in pre-clinical models. GSK239512 is a potent and selective H3 receptor antagonist developed for the treatment of cognitive dysfunction in neurodegenerative disorders. In this study we examined the safety, tolerability, pharmacokinetics and pro-cognitive effects of GSK239512 (oral) in patients with mild to moderate Alzheimers disease using ascending dose titration regimens. Methods: The study was conducted in two parts. Part A was a single-blind, placebo run-in, flexible dose titration over 9 days in two cohorts, each consisting of two patients. Part B was a double-blind, randomised, placebo controlled, parallel group, which investigated 3 flexible dose titration regimens over 4 weeks in 3 cohorts, each consisting of eight patients. Results: Overall, the 5/10/20/40g and 10/20/40/80g regimens were well-tolerated. The regimen of 20/40/80/150g showed the poorest tolerability likely due to the higher starting dose. There were no clinically significant abnormalities in haematology, clinical chemistry, urinalysis parameters and cardiovascular parameters. GSK239512 had positive effects on tasks of attention and memory with effect sizes between 0.56 and 1.37. Conclusions: GSK239512 displayed asatisfactory level of tolerability in patients with Alzheimers disease with evidence for positive effects on attention and memory. The findings suggest that a titration regimen with a starting dose of 5-10g and a maximum dose of 80g is likely to be a well-tolerated and potentially efficacious regimen for future clinical trials in patients with Alzheimers disease. These findings await replication in a larger study.

The article presents an algorithmic approach to correct registration errors and ensure accurate target tracking and display in the use of Automatic Dependent Surveillance-Broadcast (ADS-B) techniques in Air Traffic Control systems employing multi-sensor based fusion. It is stated to compute the range, azimuth and time biases in radar measurements with fast convergence. Simulation results indicate it to be a sound procedure conforming to Federal Aviation Administration (FAA) standards.

CdTe/Si substrates with etch-pit densities ~5 x 104- 2 x105cm-2and x-ray diffraction full-width at half-maximum <60 arcsec over >60% of a 3" substrate and ≤85 arcsec over the entire area are now available. Midwave and shortwave HgCdTe infrared detectors fabricated on these substrates have device characteristics as good as those of detectors fabricated on lattice-matched CdZnTe substrates. Also, minority carrier lifetimes of 100s of nanoseconds are measured for CdTe/Si and CdZnTe/Si, and both can be p-doped 1017cm-3and n-doped >1020cm-3. Calculations suggest that the use of these materials should yield multijunction solar cells with efficiencies higher than those of the corresponding III-V multijunction cells at much lower cost, using rugged, large-area, inexpensive active Si substrates. The first CdZnTe/Si single-junction solar cells fabricated by EPIR displayed an electronic-charge times open-circuit voltage, qVoc, within ~0.45 eV of the CdZnTe bandgap Eg, as good a result as that for the best III-V alloy single-junction cells, and confirmed the suitability of single-crystal CdZnTe/Si for the manufacture of high-efficiency solar cells.

Despite being impervious to surveillance by the adaptive immune system because of its lack of vascularity, infection of the nasal and auricular cartilage after surgery such as rhinoplasty or otoplasty is rare. Why is this so? Our goal was to determine whether the expression of antimicrobial peptides provides a previously unrecognized nonepithelial layer of innate immune defense within the nasal and auricular cartilage.

Selective laser melting (SLM), a method used in the nuclear, space, and racing industries, allows the creation of customized titanium alloy scaffolds with highly defined external shape and internal structure using rapid prototyping as supporting external structures within which bone tissue can grow. Human osteoblasts were cultured on SLM-produced Ti6Al4V mesh scaffolds to demonstrate biocompatibility using scanning electron microscopy (SEM), fluorescence microscopy after cell vitality staining, and common biocompatibility tests (lactate dihydrogenase (LDH), 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), 5-bromo-2-deoxyuridine (BrdU), and water soluble tetrazolium (WST)). Cell occlusion of pores of different widths (0.45–1.2 mm) was evaluated. Scaffolds were tested for resistance to compressive force. SEM investigations showed osteoblasts with well-spread morphology and multiple contact points. Cell vitality staining and biocompatibility tests confirmed osteoblast vitality and proliferation on the scaffolds. Pore overgrowth increased during 6 weeks' culture at pore widths of 0.45 and 0.5 mm, and in the course of 3 weeks for pore widths of 0.55, 0.6, and 0.7 mm. No pore occlusion was observed on pores of width 0.9–1.2 mm. Porosity and maximum compressive load at failure increased and decreased with increasing pore width, respectively. In summary, the scaffolds are biocompatible, and pore width influences pore overgrowth, resistance to compressive force, and porosity.

Introduction Endometriosis can be difficult to diagnose clinically and models that use symptoms to predict whether the disease is present or not are based on limited patient populations. Endometriosis also influences health-related quality of life, but little is known about its impact across the world. We therefore initiated two integrated multi-center studies to collect prospective, standardized, epidemiological data, to 1) examine the global impact of endometriosis and relative effect of risk-factors, and 2) develop a symptom-based diagnostic tool.Methods The Global Study of Women's Health (GSWH) and the Women's Health Symptom Survey (WHSS) prospectively recruit 18–45 year old women having a laparoscopy across 23 and 19 centers, respectively, worldwide. Women with a previous surgical diagnosis of endometriosis are excluded. Multi-lingual patient questionnaires and a surgical questionnaire, incorporating validated instruments, are used to collect the data. The GSWH aims to recruit >2,000 women by December 2009; the WHSS to recruit 1,000 women in each of the two model-generating and validation stages.Results A six-week pilot study in Oxford, UK, established the feasibility of the study protocols. Of 32 eligible women, 27 participated (response rate - 84.4%); 26% completed the questionnaire online. Endometriosis was found in 47.4%. Extrapolating the recruitment rates from the pilot study, the target sample sizes for the GWSH and WHSS were deemed feasible.Conclusions Using standardized data collection, the GSWH and WHSS will provide insight into the global impact of endometriosis and develop a validated, symptom-based, diagnostic tool. They have the potential to provide the basis for future, longitudinal, follow-up studies and a collaborative Endometriosis Biobank implementing standardized collection of DNA and tissue samples

The presence of left ventricular hypertrophy (LVH) in hypertension, as detected by the electrocardiogram or echocardiography, is associated with an increased risk of mortality and morbidity several times above and beyond the risk of hypertension alone. The LIFE (Losartan Intervention For Endpoint reduction in hypertension) study confirmed that pharmacological agents, which reduce LVH, confer further reduction in morbidity and mortality. This makes the identification of patients with LVH all the more important. In this article we describe the various methods available to diagnose the presence of LVH in patients with hypertension, and consider their strengths and their place in clinical practice and in research.

The fluorescence spectra of Bacillus spores are measured at excitation wavelengths of 280, 310, 340, 370, and 400 nm. When cluster analysis is used with the principal-component analysis, the Bacillus globigii spores can be distinguished from the other species of Bacillus spores (B. cereus, B. popilliae, and B. thuringiensis). To test how robust the identification process is with the fluorescence spectra, the B. globigii is obtained from three separate preparations in different laboratories. Furthermore the fluorescence is measured before and after washing and redrying the B. globigii spores. Using the cluster analysis of the first two or three principal components of the fluorescence spectra, one is able to distinguish B. globigii spores from the other species, independent of preparing or washing the spores.

Magnetic resonance (MR) imaging is an important tool in the evaluation of cardiac neoplasms. T1-weighted, T2-weighted, and gadolinium-enhanced sequences are used for anatomic definition and tissue characterization, whereas cine gradient-echo imaging is used to assess functional effects. Recent improvements in pulse sequences for cardiac MR imaging have led to superior image quality, with reduced motion artifact and improved signal-to-noise ratio and tissue contrast. Although there is some overlap in the MR imaging appearances of cardiac tumors, particularly of primary malignancies, differences in characteristic locations and features should allow confident differentiation between benign and malignant tumors. Indicators of malignancy at MR imaging are invasive behavior, involvement of the right side of the heart or the pericardium, tissue inhomogeneity, diameter greater than 5 cm, and enhancement after administration of gadolinium contrast material (as a result of higher tissue vascularity). Concomitant pericardial or pleural effusions are rare in benign processes but occur in about 50% of cases of malignant tumors. MR imaging offers improved resolution, a larger field of view, and superior soft-tissue contrast compared with those of echocardiography, suggesting that knowledge of the MR imaging features of cardiac neoplasms is important for accurate diagnosis and management. © RSNA, 2005

Dipicolinic acid (DPA) and the Ca^2+ complex of DPA (CaDPA) are major chemical components of bacterial spores. With fluorescence being considered for the detection and identification of spores, it is important to understand the optical properties of the major components of the spores. We report in some detail on the room-temperature fluorescence excitation and emission spectra of DPA and its calcium ion complex and provide a comparison of the excitation–emission spectrum in a dry, wet paste and aqueous form. DPA solutions have weak, if any, fluorescence, with increased fluorescence when the DPA is dry. After exposure to a broad source UV light of the DPA, wet or dry, we observe a large increase in fluorescence with a maximum intensity emission peak at around 440 nm for excitation light with a wavelength of around 360 nm. There is a slight blueshift in the absorption spectra of UV-exposed DPA from the unexposed DPA solution. CaDPA in solution shows a slight fluorescence with increased fluorescence in the dry form, and a substantial increase of fluorescence was observed after UV exposure with an emission peak of around 410 nm for excitation around 305 nm. The detailed excitation–emission spectra are necessary for better interpretation of the fluorescence spectra of bacterial spores where DPA is a major chemical component.

Purpose. To report the outcome of revised total hip arthroplasty procedures involving an anterior cortical window, extensive strut allografts, and an Exeter impaction graft.Method. Eight patients (9 hips) with a mean age of 58 years underwent revision of total hip arthroplasty using the Exeter hip impaction graft system and strut allografts between 1995 and 1998. An extensile anterior approach was used, and an anterior cortical window was created in the femur, to remove the old implant. External strut allografts were attached by wires to provide cortical support. The mean follow-up duration was 74 months. Indications for surgery were aseptic loosening of previous implants in 8 hips and infection of one hip that had previously undergone total arthroplasty.Results. 19 Dall Miles cables, 4 ordinary cerclage wires, and 8 cerclage wires tightened with the clincher knot technique were used to secure the allograft to the host bone. The strut grafts were found to be incorporated in all cases. No wires became loose. One patient developed 20° of angulation at the allograft-host bone junction. Using the method of Fowler and Gie, we found that one femoral implant had subsided 2 mm within the cement mantle. Two other implants had 1 mm of subsidence at the cement bone interface, and one patient had a major subsidence of 15 mm that required revision.Conclusion. Using an anterior cortical window in the femur to remove the old implant does not predispose to failure of the allograft to incorporate into the host bone.

Purpose. To evaluate the clinical and radiological outcome in patients undergoing small stem Exeter total hip replacement.Methods. A total of 46 small stem Exeter total hip replacements were performed on 44 consecutive patients (18 men and 26 women) attending the University of Malaya Medical Centre. The mean age at the time of operation was 58 years (range, 24–81 years). Of the 46 procedures performed, 35 were primary total hip replacements and 11 were revision operations, with aseptic loosening of the original implant being the main indication for revision. The main indications for surgery in primary cases were avascular necrosis and rheumatoid arthritis. Clinical and radiographic outcomes were assessed at 6 weeks', 12 weeks', 6 months' follow-up, and annually thereafter. Postoperative cementing technique was also assessed.Results. The mean follow-up period was 4 years. The mean Oxford Hip Score improved from 46 points preoperatively to 17 points at the final follow-up examination. There were no revision operations, no implant breakages, and no excessive migration of the implants. The potential complications of implant failure due to smaller implant size and increased patient activity were not observed.Conclusion. Due to the smaller size of Asian femora, the small stem Exeter implant is a very useful development. This study suggests that it will perform as well as its larger counterparts.

The calculation of ejection fraction using gated single photon emission computed tomography SPECT has been widely validated against a range of other techniques. There have been fewer studies validating left ventricular volumes. We compared quantitative gated SPECT QGS with magnetic resonance imaging MRI measurements of left ventricular ejection fraction and end diastolic volume in 50 patients with a large range of ventricular dimensions. MRI data were obtained using a turbo gradient echo pulse sequence TGE in 17 patients and a steady state free precession pulse sequence SSFP in 33 patients. There was good correlation between ejection fraction and end diastolic volume measurements from SPECT and MRI r0.82, r0.90, respectively but the mean SPECT values were significantly lower ejection fraction, 6.6 ± 6.4 points end diastolic volume, 18.4 ± 25.4 ml than those obtained from MRI. BlandAltman analysis showed some large differences in individual patients but no trends in the data either in ejection fraction over a range from 15 to 70 or in end diastolic volume, range 75–400 ml. SSFP gave a larger difference for end diastolic volume measurement compared to SPECT than did TGE, although this difference did not reach significance. Both SSFP and TGE gave similar values for the difference between MRI and SPECT for the measurement of ejection fraction. We suggest that the difference in EF may be a result of 8 frames being used for gating in QGS but 12–18 for MR. Differences in volumes may be related to the different spatial resolution and the exclusion or inclusion of trabeculation and papillary muscles between SPECT and MRI. Differences between SSFP and TGE may be caused by differing delineation of the endocardial border, dependent on the particular acquisition sequence. In conclusion, QGS values correlated well with MRI, but a correction factor may be needed if direct comparison is made. © 2003 Lippincott Williams & Wilkins

In this study we assessed the use of a steady state free precession (SSFP) cine sequence in a series of radially orientated long axis slices for the measurement of left ventricular volumes and mass. We validated the radial long axis approach in phantoms and ex vivo porcine hearts and applied it to normal volunteers and patients using the SSFP and turbo gradient‐echo (TGE) sequences. High quality images were obtained for analysis, and the measured volumes with radial long axis SSFP sequence correlated well with short axis TGE and SSFP volumes (r > 0.98). The best interobserver agreement for left ventricular volumes was obtained using SSFP in the long axis radial orientation (variability < 2.3%). We conclude that this combination of sequence and scan orientation has intrinsic advantages for image analysis due to the improved contrast and the avoidance of errors associated with the basal slice in the short axis orientation. J. Magn. Reson. Imaging 2001;14:685–692. © 2001 Wiley‐Liss, Inc.

We evaluated the use of adenosine, dobutamine and arbutamine with 99mTc-tetrofosmin myocardial perfusion imaging. Forty patients under investigation for suspected coronary artery disease were recruited. Each had a resting scan and two separate stress scans on different days, in a randomized cross-over study. Resultant images were blindly reported in 13 segments per scan as normal, reversible or fixed defects. A score was given (0-3) for segmental defect severity. Haemodynamic responses were as expected for each agent. Subjective side effect scores did not differ overall between agents. Adenosine caused a significantly higher incidence of abnormal taste (54) than dobutamine and arbutamine (both 23) and a lower incidence of palpitations (25 vs 69 and 54, respectively), all P<0.05. Arbutamine caused significantly more chest pain than adenosine (77 vs 46) though less flushing (35 vs 68), both P<0.05. Comparison of the results obtained showed highly significant levels of segmental agreement for visual and semi-quantitative analysis between adenosine and arbutamine, κ value and correlation coefficient of 0.78 and 0.86, respectively, dobutamine and adenosine 0.69 and 0.78, and arbutamine and dobutamine 0.75 and 0.78, all P<0.0001. Adenosine, arbutamine and dobutamine differ in their haemodynamic response and side effect profile but provide highly comparable results during 99mTc SPECT imaging.

Primary leiomyosarcoma of the breast is very rare and represents a diagnostic challenge. Only 16 cases have been reported in the English language literature. We report another new case and have analysed reports of the previous cases aiming to present a simple evidence-based approach to the clinical, radiological and pathological diagnosis of this rare tumour.

Steady‐state free precession imaging is a promising technique for cardiac magnetic resonance imaging (MRI), as it provides improved blood/myocardial contrast in shorter acquisition times compared with conventional gradient‐echo acquisition. The better contrast could improve observer agreement and automatic detection of cardiac contours for volumetric assessment of the ventricles, but measurements might differ from those obtained using conventional methods. We compared volumetric measurements, observer variabilities, and automatic contour detection between a steady‐state free precession imaging sequence (BFFE = balanced fast field echo) and segmented k‐space gradient‐echo acquisition (TFE = turbo field echo) in 41 subjects. With BFFE, significantly higher end‐diastolic and end‐systolic volumes and lower wall thickness, ventricular mass, ejection fraction, and wall motion were observed (P< 0.0001), while interobserver variabilities were lower and automatic contour detection of endocardial contours was more successful. We conclude that the improved image quality of BFFE reduces the observer‐dependence of volumetric measurements of the left ventricle (LV) but results in significantly different values in comparison to TFE measurements. J. Magn. Reson. Imaging 2001;14:230–236. © 2001 Wiley‐Liss, Inc.

A real‐time magnetic resonance imaging (MRI) acquisition sequence was evaluated for the assessment of left ventricular wall motion (WM) and wall thickening (WT). Ten normal volunteers and 21 patients were studied. Short‐axis cine images of the left ventricle (LV) were acquired with a fast gradient echo and an ultrafast segmented echo‐planar imaging (EPI) sequence. Qualitative and quantitative analysis of WM and WT was performed on a segmental basis. Qualitative scores agreed between the two methods in 691 of 724 segments (95.4%) with good reproducibility. Quantitative measurements of WM and WT were significantly lower (P< 0.001) with the real‐time method (WM: mean bias, 0.49mm; WT: mean bias, 0.61mm). The largest differences were observed in the anterior and lateral segments and in patients with dilated ventricles. The lower resolution of the real‐time sequence and artifacts was probably responsible for these differences. In conclusion, real‐time cardiac MRI can be used for qualitative assessment of wall dynamics but is presently insufficient for quantitative analysis. J. Magn. Reson. Imaging 2001;14:23–30. © 2001 Wiley‐Liss, Inc.

Magnetic resonance (MR) is well suited to imaging the pericardium. High resolution images synchronized with the cardiac cycle can be obtained in any plane. The wide field of view allows additional anatomical and functional information to be obtained from adjacent structures such as the aorta, pleura, lungs and mediastinum. MR is particularly useful in cases of pericardial constriction without an associated effusion, in patients with complex or loculated pericardial effusions and in pericardial tumours. In this article we illustrate the characteristic MR features of a variety of pericardial pathologies.

Positron emission tomography (PET) imaging has become established as a diagnostic tool in cardiovascular imaging. The most important clinical applications in cardiology are the assessment of myocardial perfusion and metabolism. Tracers used for perfusion imaging include¹⁵O-labelled water,¹³N ammonia and⁸²Rb. For metabolic studies,¹¹C palmitate,¹¹C acetate and¹⁸F-2-fluoro-2-deoxyglucose (FDG) are used. Studies of myocardial metabolism are of particular value in the assessment of myocardial viability in patients with ischaemic heart disease and impaired left ventricular function. Restoration of blood flow to regions of underperfused but viable myocardium (‘hibernating myocardium’) can improve left ventricular function in this patient-group. PET imaging with FDG provides positive predictive values of approximately 72%, and negative predictive values of around 83% for improvement of left ventricular function following revascularization in these patients. Other applications of PET in cardiology include the assessment of sympathetic receptor density and distribution in the heart. The use of PET imaging is currently limited mainly by its high cost and low availability, but low-cost PET systems are being developed and coincidence imaging with gamma cameras is another developing alternative to PET. Other imaging techniques such as dobutamine stress echocardiography, thallium reinjection imaging, SPECT and MRI are also continuing to improve and have to be compared to PET imaging. The future role of PET in cardiology is expected to increase as a result of developments in the technology and the availability of lower-cost systems. Copyright 2001 The College of Radiographers

18F-Fluorodeoxyglucose positron emission tomography (18FDG PET) is the recognized gold standard for the assessment of myocardial viability, but is not widely available in the UK. FDG imaging on a gamma camera with high-energy collimators (FDG SPECT) has been shown to have an accuracy comparable with that of FDG PET for the assessment of myocardial viability. This study was performed to assess the feasibility of introducing FDG SPECT for myocardial viability at a hospital a considerable distance away from a cyclotron (200 miles). Twenty-three patients, who were being actively considered for revascularization but had demonstrated fixed defects on stressrest with nitrate tetrofosmin imaging, underwent FDG SPECT. Image quality was acceptable in all patients. Nine out of the 23 patients with defects classed as fixed on tetrofosmin imaging demonstrated viability on FDG SPECT. Six of these nine patients, reported to have some viable myocardium on FDG SPECT, underwent revascularization as a result. This study has demonstrated that FDG SPECT is feasible at a site some distance from a cyclotron.

Abstract: In this work in-situ spectroscopic ellipsometry (SE) has been applied for the simultaneous determination of the growth temperature and alloy composition for the epitaxial Cd1−xZnxTe(211)/Si(211) structure. The optical dielectric functions of CdTe and Cd0.96Zn0.04Te (CZT) epilayers were studied as a function of temperature both ex-situ and in-situ in the range from 1.6 eV to 4.5 eV. We employed parametric models for the simulation of the optical properties of CZT at and between the critical points (CP) E0, E0 + Δ0, E1, E1 + Δ1, E2(Σ) and E2(Σ). Critical point energies and line widths for Cd1−xZnxTe were obtained through the fitting process, which included both zero order and higher order derivatives of the SE pseudo dielectric function. The dependence of the different critical points on Zn concentration x is discussed. It has been demonstrated that the energy of the weak E0 + Δ0 transition can be used to measure composition, while the E1 energy can be used as a real-time temperature measure. The model parameters were optimized through the simultaneous analysis of multiple data sets, and the temperature dependent model was developed for in-situ application. Our analysis is estimated to produce uncertainties of only �0.5�C in measuring the temperature and �0.5% in measuring the composition of only the zero order dielectric function is being fitted. The effects of a surface overlayer, of reflected beam deflections, and of other experimental problems on the overall accuracy, are discussed as well as ways to improve the in-situ SE data quality.

Abstract: The p-type doping of Hg1−xCdxTe (MCT) has proven to be a significant challenge in present day MCT-based detector technology. One of the most promising acceptor candidates, arsenic, behaves as an amphoteric dopant which can be activated as an acceptor during Hg-rich, low temperature annealing of as-grown molecular beam epitaxy (MBE) samples. This study focuses on developing an understanding of the microscopic behavior of arsenic incorporation during MBE growth. In particular, the question of whether arsenic incorporates as individual As atoms, as As2 dimers, or as As4 tetramers is addressed for MBE growth with an As4 source. A quasithermodynamical model is employed to describe the MCT growth and As incorporation, with parameters fitted to an extensive database of samples grown at the Microphysics Laboratory. The best fits for growth temperatures between 175 and 185C are obtained for arsenic incorporation as As4 or possibly as As4 clusters, with lower probabilities for As2 and individual As atoms. Based on these results, we investigate the relaxed atomic configurations of As4 and As2 in bulk HgTe by ab initio total energy calculations. The calculations are performed in the pseudopotential density-functional framework within the local density approximation, employing supercells with periodic boundary conditions. The lattice distortions due to As4 and As2 in bulk HgTe are predicted to be modest due to the small size of these arsenic clusters.

Abstract: Optical real-time in-situ sensors play a very important role in the processing of semiconductor devices because of their noncontact remote nature and excellent compatibility with UHV systems. In this work, we report on progress in developing an in-situ temperature sensor for HgCdTe structures grown by molecular beam epitaxy (MBE). Based on the Fourier transform infrared (FTIR) spectrometer, this sensor is capable of continuous real-time monitoring of the surface temperature, thickness and alloy composition of HgCdTe epilayers. The accuracy and sensitivity of this FTIR technique were studied in all temperature ranges of interest. Also compared are two different methods of temperature determination obtained from the normalized spectral radiance. The influence of stray radiation and of sample holder rotation on the measurement accuracy have been studied. Reflectivity spectra for HgCdTe/CdZnTe(211) and HgCdTe/CdTe(211)/Si(211) structures have been analyzed in real time in order to determine the layer thickness and alloy composition for growing layers. Also discussed is a multilayer-structure optical model developed to solve the problem of composition determination at early stages of growth. The application of this model for fitting the transmission spectra is demonstrated.

To evaluate the results of percutaneous transluminal angioplasty (PTA) of the tibial vessels, results of 50 procedures performed in 38 patients since 1988 were analysed retrospectively. A total of 73 tibial vessels were treated: 32 anterior tibial arteries, 16 posterior tibial arteries, four peroneal arteries, 12 tibioperoneal trunks and nine trifurcation lesions. Forty-four of 50 PTA procedures were performed in conjunction with interventions in the femoropopliteal arteries and six as isolated procedures. One patient required a femorodistal graft following perforation of the popliteal artery during atherectomy. Distal emboli occurred in two patients and acute thrombosis of both the angioplastied tibial vessels occurred in a third. The technical success rate was 96 per cent. Patients were followed for a mean(s.d.) of 21(13) months. At the latest follow-up, 58 per cent had improved clinically. There were significant improvements in 43 per cent of limb isotope blood flow studies and 52 per cent of ankle : brachial Doppler pressure indices in treated limbs at this time. PTA should be the first treatment option in patients with infrapopliteal arterial disease needing intervention, whenever it is technically feasible.

Abstract: The alloy composition of Hg1−xCdxTe should be controlled during growth, so that the desired band gap and the lattice-matched layer may be obtained. In-situ spectroscopic ellipsometry, now commercially available, enables one to acquire spectral data during growth. If one knows the optical dielectric function as a function of alloy composition and temperature, the technique can be fully used to monitor and control temperature, the thickness, and the alloy composition. For this purpose, we first obtained temperature dependent spectral data of Hg1−xCdxTe by spectroscopic ellipsometry (SE). The spectral data of Hg1−xCdxTe with x = 1,0.235, and 0.344 were obtained from room temperature to 800Kin the photon energy range from 1.3 to 6 eV. The spectral data revealed distinctive critical point structures at E0, E0+Δ0, E1, E1+Δ1, E2(X), and E2(Σ). Critical point energies decreased and linewidths increased monotonically as temperature increased. The model for the optical dielectric function enabled (i) the critical point parameters to be determined accurately, and (ii) the spectral data to be expressed as a function of temperature within and outside the experimental range.

Zinc-blende MnSZnSeheterostructures on GaAs(100) have been characterized by X-ray photoelectron spectroscopy (XPS), optical methods, and transmission electron microscopy (TEM). XPS spectra indicated that the MnSZnSeinterface is sharp and that the layers are of proper stoichiometry. TEM revealed isolated {111} stacking faults but confirmed the overall high crystalline quality and coherence of the MnSZnSeinterface. XPS suggests a small valence band discontinuity (ΔEv) of about 140 meV with a type IIA alignment. This result was supported by low-temperature photoluminescence (PL) measurements on a MnsZnSesuperlattice. No peaks were observed above the ZnSe band gap suggesting that the alignment was not type I. A previously unobserved broad PL peak was seen at about 2.77–2.78 eV, approximately 50 meV below the ZnSe bandgap.

We describe the photoluminescence and reflectance properties of Zn1 − xMnxSySe1 − ygrown by molecular beam epitaxy on (100) GaAs substrates. A range of compositions has been explored with lattice constants ranging from 5.48 to 5.71 Å, and 300 (1.7) K bandgaps ranging from 2.68 (2.79) to 3.43 (3.65) eV. A multiple quantum well heterostructure with ZnSe wells exhibits quantum confinement up to 2.91 eV. The material is of potential interest as a lattice-matched cladding layer in ZnSe-based separate confinement heterostructure short wavelength lasers.

Photoconductor linear array detectors for hard X-ray photon detection were fabricated using Molecular Beam Epitaxially (MBE) grown (111)B CdTe on (100) Si substrates. The ohmic contact to the CdTe was excellent and provided a linear response to the X-ray photons. The response current was linearly increased in a 7–19 keV energy range. The stability of the detectors was very satisfactory and they were tested over an extended period of time without noticeable degradation. The excellent response uniformity of a 64 linear array was obtained. The performance of the photoconductor was greatly improved when the detector was cooled. At 230 K, the dynamic range of the detector response increased to nearly four decades.

Nitrates can be used to improve resting myocardial blood flow in patients with severe coronary artery disease. This may enhance tracer uptake during rest myocardial perfusion imaging. Recent studies using nitrates at rest have shown increased detection of reversible ischaemia in this patient group with the 201T1 and 99Tcmperfusion tracers MIBI and tetrofosmin. However, it is not always possible to assess the severity of coronary artery disease before the rest injection and therefore whether a patient would benefit from nitrate administration. To improve the sensitivity for the detection of reversible ischaemia and to avoid a repeat study with nitrates (especially in patients with ‘fixed’ defects), a protocol in which all patients routinely receive nitrates prior to the rest injection is required. This prospective study evaluated the effect of nitrate administration prior to rest imaging in a randomly selected group of patients. Thirty patients selected at random from routine referrals had stress, rest and rest + GTN tetrofosmin imaging on three separate days. Changes in reversibility between the rest and rest + GTN images were assessed both visually and using semi-quantitative analysis. Defects at stress were seen in 43 coronary artery territories, 33 of which were reversible at rest and 37 reversible at rest + GTN. Of these 43 defects, 82 demonstrated either increased or the same degree of reversibility at rest + GTN imaging compared to standard rest imaging. All defects with reduced reversibility at rest + GTN imaging (i.e. the remaining 18) were, however, still reversible compared to the stress images. Some of this reduced reversibility may be due to attenuation artefacts. We conclude that the routine use of GTN with rest tetrofosmin imaging will result in increased detection of ischaemic areas with no loss of sensitivity or specificity.

Simulation of MR images is a useful tool for offline sequence development and as an aid to understanding image formation. One particular application of simulation is MR tagging, which is used for tracking myocardial motion. Simple spatial‐domain methods cannot adequately represent effects common in these images, such as motion artifact and signal wrap. An existing frequency‐domain model is shown to be inappropriate for tagged images, and an extension based on the Bloch equations and Fourier shift theorem is described to correct this. Software incorporating the new model is used to generate ideal tag intensity profiles and to accurately simulate tagged images. The shifted k‐space patterns associated with tagged images, and their dependence on the order of the binomial tagging sequence, are explained. An application of the Fourier shift theorem is suggested that allows more rapid simulation of static tagged images.

MR tagging is a recent imaging development that, in cardiac applications, makes possible the tracking of points in the myocardium during the cardiac cycle. Researchers have developed semiautomated, computer‐based methods for analyzing tagged images, but the images are complex and present a challenge to automated tracking systems. Simulation can provide an inexhaustible supply of images for testing and validation of tag tracking software and preview the effect of parameter changes in acquisition. SIMTAG is an interactive computer program that simulates two‐dimensional tagged‐MR experiments. The mathematic model used in the simulation and algorithms for simulating image noise and object deformation are described. Examples of the use of simulated images in SPAMM parameter selection, a comparison of tag contrast in signal‐averaged SPAMM and CSPAMM, and simulated images as test sets for tag‐tracking software are presented.

We report on the electrical and electro-optical properties of n- and p-type (211)B mercury cadmium telluride grown by molecular beam epitaxy for Cd composition ∼ 0.22. Grown layers show excellent structural qualities with DCRC FWHM of 25–40 arcsec. However, in the unintentionally doped layers a complex picture of transport characteristics were observed. Indium doped layers grown on Nippon Mining substrates show excellent Hall characteristics and minority carrier lifetimes down to 1 × 1015cm−3doping levels. But, when the net doping level falls below ∼ 2 × 1015cm−3, the measured lifetime data indicates Shockly-Read (SR) recombination centers. We believe that these SR levels are related to Hg vacancies. Also, arsenic is being investigated as a p-type dopant through a new approach called “planar doping” for MBE-HgCdTe. The obtained results are very promising. During the growth process using this method, the incorporated arsenic can be electrically activated at a temperature not exceeding 250°C.