Inter-comparison of hemispherical conical reflectance factors (HCRF) measured with four fibre-based spectrometers.

We describe the results of an experiment designed to compare the radiometric performance of four different spectroradiometers in ideal field conditions. A carefully designed experiment where instruments were simultaneously triggered was used to measure the Hemispherical Conical Reflectance Factors (HCRF) of four targets of varying reflectance. The experiment was in two parts. Stage 1 covered a 2 hour period finishing at solar noon, where 50 measurements of the targets were collected in sequence. Stage 2 comprised 10 rapid sequential measurements over each target. We applied a method for normalising full width half maximum (FWHM) differences between the instruments, which was a source of variability in the raw data. The work allowed us to determine data reproducibility, and we found that lower-cost instruments (Ocean Optics and PP Systems) produced data of similar radiometric quality to those manufactured by Analytical Spectral Devices (ASD -here we used the ASD FieldSpec Pro) in the spectral range 400-850 nm, which is the most significant region for research communities interested in measuring vegetation dynamics. Over the longer time-series there were changes in HCRF caused by the structural and spectral characteristics of some targets.

Outcomes of preoperative angiotensin-converting enzyme inhibitor therapy in patients undergoing isolated coronary artery bypass grafting.

The association between preoperative use of angiotensin-converting enzyme (ACE) inhibitors and outcomes after coronary artery bypass grafting (CABG) remain controversial. Our aim was to study in-hospital outcomes after isolated CABG in patients on preoperative ACE inhibitors. A retrospective analysis of 8,889 patients who underwent isolated CABG from 2000 through 2011 was conducted. The primary outcome of interest was the incidence of major adverse events (MAEs) defined as a composite of mortality, postoperative renal dysfunction, myocardial infarction, stroke, and atrial fibrillation during index hospitalization. The secondary outcome was the incidence of individual outcomes included in MAEs. Logistic regression analyses were performed. Of 8,889 patients, 3,983 (45%) were on preoperative ACE inhibitors and 4,906 (55%) were not. Overall incidence of MAEs was 38.1% (n = 1,518) in the ACE inhibitor group compared to 33.6% (n = 1,649) in the no-ACE inhibitor group. Preoperative use of ACE inhibitors was independently associated with MAEs (odds ratio 1.13, 95% confidence interval 1.03 to 1.24), most of which was driven by a statistically significant increase in postoperative renal dysfunction (odds ratio 1.18, 95% confidence interval 1.03 to 1.36) and atrial fibrillation (odds ratio 1.15, 95% confidence interval 1.05 to 1.27). In-hospital mortality, postoperative myocardial infarction, and stroke were not significantly associated with preoperative ACE inhibitor use. Analyses performed after excluding patients with low ejection fractions yielded similar results. In conclusion, preoperative ACE inhibitor use was associated with an increased risk of MAEs after CABG, in particular postoperative renal dysfunction and atrial fibrillation.

Regional myocardial deformation in children with hypertrophic cardiomyopathy: morphological and clinical correlations.

AIMS: Hypertrophic cardiomyopathy (HCM) is a disease with marked regional differences in wall thickness. However, the relation between myocardial function and wall thickness has not been well studied. Ultrasonic strain rate (SR) imaging makes it possible to study the regional myocardial deformation. We investigated whether regional systolic deformation is reduced in paediatric patients with HCM and evaluated its relation with wall thickness, electrocardiographic pattern, and exercise capacity. METHODS AND RESULTS: We studied 41 children with asymmetric HCM (mean age 12.3 years) and 29 controls. Electrocardiograms, exercise testing (when feasible), and echocardiograms with tissue Doppler imaging were performed. Peak systolic SR, strain, post-systolic shortening, and time to maximal strain were calculated in the longitudinal direction from the basal septum, mid-septum, and basal lateral myocardial segments and in the radial direction from the basal antero-septal and infero-lateral myocardial segments. Children with HCM had a significant reduction in deformation in all myocardial segments when compared with controls. In the HCM group, peak systolic SR and strain were significantly lower in the basal septum when compared with the mid-septal and basal lateral myocardial segments. In the basal septum, post-systolic shortening was significantly higher and time to maximal strain significantly longer than in mid-septal and lateral myocardial segments. A strong inverse curvilinear relation between peak systolic strain and wall thickness was found (r = -0.86, P < 0.001), with no further decrease in the regional myocardial function demonstrated once maximal wall thickness exceeded a Z-score of 3.5. Peak systolic strain in the basal part of the septum correlated inversely with exercise capacity (r = 0.68, P < 0.01). CONCLUSION: Systolic deformation is significantly and inhomogeneously reduced in children with HCM. This reduction in myocardial function is related to maximal wall thickness and decreased exercise capacity.

Characteristics of drug resistance and HIV among tuberculosis patients in Mozambique.

SETTING: The rate of human immunodeficiency virus (HIV) seroprevalence among tuberculosis patients varies between 2% and 53% in Mozambique, depending on the region. Drug resistance surveillance has been performed in only a few cities in Mozambique. OBJECTIVES: To establish the extent of drug resistance in areas of Mozambique with different levels of HIV prevalence, to estimate the prevalence of HIV among tuberculosis (TB) patients, and to examine the association between drug resistance and HIV infection. DESIGN: All tuberculosis patients diagnosed at randomly selected health facilities over 9 months (September 1998 to June 1999) were enrolled in the study. Sputum was collected, smeared and cultured, and drug susceptibility tests were performed. Blood was tested for HIV in the respective provinces, and patients received pre-test and post-test counselling. RESULTS: Of 709 culture-positive cases, 25.5% were HIV-positive. HIV-positive patients were significantly more likely to have a prior history of treatment (OR 2.2; 95% CI 1.9-3.6) and resistance to both isoniazid and streptomycin (OR 2.3; 95% CI 1.3, 4.5). In patients with no history of prior tuberculosis treatment, the multidrug resistance rate was 3.4% and resistance to isoniazid and streptomycin (HS) was 5.2%. Any drug resistance was significantly more common among those with a history of prior treatment (OR 3.1; 95% CI 2.1-4.7), particularly resistance to HS (OR 4.5; 95% CI 2.6-7.9). CONCLUSIONS: This study demonstrates substantial levels of drug resistance in Mozambique. Differences in drug resistance between high and low HIV prevalence areas may be related to prior treatment.