Estimation of physical variables from multichannel remotely sensed imagery using a neural network: Application to rainfall estimation

Satellite-based remotely sensed data have the potential to provide hydrologically relevant information about spatially and temporally varying physical variables. A methodology for estimating such variables from multichannel remotely sensed data is presented; the approach is based on a modified counterpropagation neural network (MCPN) and is both effective and efficient at building complex nonlinear input-output function mappings from large amounts of data. An application to high-resolution estimation of the spatial and temporal variation of surface rainfall using geostationary satellite infrared and visible imagery is presented. Test results also indicate that spatially and temporally sparse ground-based observations can be assimilated via an adaptive implementation of the MCPN method, thereby allowing on-line improvement of the estimates

Improved streamflow forecasting using self-organizing radial basis function artificial neural networks

Streamflow forecasting has always been a challenging task for water resources engineers and managers and a major component of water resources system control. In this study, we explore the applicability of a Self Organizing Radial Basis (SORB) function to one-step ahead forecasting of daily streamflow. SORB uses a Gaussian Radial Basis Function architecture in conjunction with the Self-Organizing Feature Map (SOFM) used in data classification. SORB outperforms the two other ANN algorithms, the well known Multi-layer Feedforward Network (MFN) and Self-Organizing Linear Output map (SOLO) neural network for simulation of daily streamflow in the semi-arid Salt River basin. The applicability of the linear regression model was also investigated and concluded that the regression model is not reliable for this study. To generalize the model and derive a robust parameter set, cross-validation is applied and its outcome is compared with the split sample test. Cross-validation justifies the validity of the nonlinear relationship set up between input and output data. © 2004 Elsevier B.V. All rights reserved

Self-organizing linear output map (SOLO): An artificial neural network suitable for hydrologic modeling and analysis

Artificial neural networks (ANNs) can be useful in the prediction of hydrologic variables, such as streamflow, particularly when the underlying processes have complex nonlinear interrelationships. However, conventional ANN structures suffer from network training issues that significantly limit their widespread application. This paper presents a multivariate ANN procedure entitled self-organizing linear output map (SOLO), whose structure has been designed for rapid, precise, and inexpensive estimation of network structure/parameters and system outputs. More important, SOLO provides features that facilitate insight into the underlying processes, thereby extending its usefulness beyond forecast applications as a tool for scientific investigations. These characteristics are demonstrated using a classic rainfall-runoff forecasting problem. Various aspects of model performance are evaluated in comparison with other commonly used modeling approaches, including multilayer feedforward ANNs, linear time series modeling, and conceptual rainfall-runoff modeling

Xpert MTB/RIF - why the lack of morbidity and mortality impact in intervention trials?

: Compared with smear microscopy, the Xpert MTB/RIF assay (Xpert), with superior accuracy and capacity to diagnose rifampicin resistance, has advanced TB diagnostic capability. However, recent trials of Xpert impact have not demonstrated reductions in patient morbidity and mortality. We conducted a narrative review of Xpert impact trials to summarize which patient-relevant outcomes Xpert has improved and explore reasons for no observed morbidity or mortality reductions. We searched PubMed, Google Scholar, Cochrane Library and Embase and identified eight trials meeting inclusion criteria: three individually randomized, three cluster-randomized, and two pre-post trials. In six trials Xpert increased diagnostic yield of bacteriologically-confirmed TB from sputa and in four trials Xpert shortened time to TB treatment. However, all-cause mortality was similar between arms in all six trials reporting this outcome, and the only trial to assess Xpert impact on morbidity reported no impact. Trial characteristics that might explain lack of observed impact on morbidity and mortality include: higher rates of empiric TB treatment in microscopy compared with Xpert arms, enrollment of study populations not comprised exclusively of populations most likely to benefit from Xpert, and health system weaknesses. So far as equipoise exists, future trials that address past limitations are needed to inform Xpert use in resource-limited settings.<br/

Mucormycosis (zygomycosis) of renal allograft

Fungal infection is relatively common among renal transplant recipients from developing countries. Mucormycosis, also known as zygomycosis, is one of the most serious fungal infections in these patients. The most common of presentation is rhino-cerebral. Isolated involvement of a renal allograft is very rare. A thorough search of literature and our medical records yielded a total of 24 cases with mucormycosis of the transplanted kidney. There was an association with cytomegalovirus (CMV) infection and anti-rejection treatment in these patients and most of these transplants were performed in the developing countries from unrelated donors. The outcome was very poor with an early mortality in 13 (54.5%) patients. Renal allograft mucormycosis is a relatively rare and potentially fatal complication following renal transplantation. Early diagnosis, graft nephrectomy and appropriate antifungal therapy may result in an improved prognosis for these patients

Impact of ethnicity and extreme prematurity on infant pulmonary function.

The impact of birth before 27 completed weeks of gestation on infant pulmonary function (PF) was explored in a multi-ethnic population in comparison to more mature preterm controls (PTC) and healthy fullterm infants. Plethysmographic lung volume (FRCpleth ) and forced expired volume (FEV0.5 ) were obtained at ∼12 months post-term age in 52 extremely preterm (EP) infants (median [range] gestational age [GA]: 26 [23-27] weeks; 40% White mothers; 79% with BPD), 41 PTC (GA:35 [30-36] weeks; 37% White mothers) and 95 fullterm infants (GA:40 [37-42] weeks; 86% White mothers). Using reference equations based on identical equipment and techniques, results were expressed as z-scores to adjust for age, sex and body size. FEV0.5 was significantly lower in EP infants when compared with PTC (mean difference [95% CI]: -1.02[-1.60; -0.44] z-scores, P < 0.001), as was forced vital capacity (FVC) but there were no significant differences in FRCpleth or FEV0.5 /FVC ratio. FEV0.5 , FVC, and FEV0.5 /FVC were significantly lower in both preterm groups when compared with fullterm controls. On multivariable analyses of the combined preterm dataset: FEV0.5 at ∼1 year was 0.11 [0.05; 0.17] z-scores higher/week GA, and 1.28 (0.49; 2.08) z-scores lower in EP infants with prior BPD. Among non-white preterm infants, FEV0.5 was 0.70 (0.17; 1.24) z-scores lower, with similar reductions in FVC, such that there were no ethnic differences in FEV0.5 /FVC. Similar ethnic differences were observed among fullterm infants. These results confirm the negative impact of preterm birth on subsequent lung development, especially following a diagnosis of BPD, and emphasize the importance of taking ethnic background into account when interpreting results during infancy as in older subjects. Pediatr Pulmonol. © 2013 Wiley Periodicals, Inc

Effect of vitamin D supplementation on serum sclerostin levels in chronic kidney disease.

Vitamin D deficiency, cardiovascular disease and abnormal bone mineral metabolism are common in chronic kidney disease (CKD). Abnormal bone mineral metabolism has been linked to vascular calcification in CKD. Sclerostin has emerged as an important messenger in cross talk between bone-vascular axis. We analyzed sclerostin in subjects who participated in the randomized, double blind, placebo controlled trial investigating the effect of cholecalciferol supplementation on vascular function in non-diabetic CKD stage G3-4 and vitamin D ≤20ng/ml [CTRI/2013/05/003648]. Patients were randomized (1:1) to receive either two directly observed oral doses of 300,000 IU of cholecalciferol or matching placebo at baseline and 8 weeks. Of the 120 subjects enrolled, 58 in the cholecalciferol group and 59 in the placebo group completed the study. At baseline, serum levels of sclerostin were similar in both groups (cholecalciferol - median;190pg/ml, IQR;140-260pg/ml and placebo - median;180pg/ml, IQR; 140-240pg/ml, p=0.67). 16 weeks after cholecalciferol supplementation, there was no change in level of sclerostin (mean change;1.10 pg/ml, 95%CI; -27.34 to 29.34 pg/ml, p=0.25). However, a significant decrease in sclerostin level was noted in the placebo group (mean change; -31.94pg/ml, 95%CI; -54.76 to -9.13 pg/ml, p=0.002). Change (Δ) in sclerostin level at 16 weeks correlated negatively with Δ eGFR (r=-0.20, p=0.03) and positively with Δuric acid (r=0.37, p<0.001) but not with Δ25(OH) D (r=0.06, p=0.54), Δ iPTH (r=-0.03, p=0.78) ΔFGF23 (r=-0.08, p=0.38) and Δ1,25 (OH)2 D (r=-0.04, p=0.65). In conclusion, high dose cholecalciferol supplementation did not change sclerostin levels in non-diabetic stage 3-4 CKD subjects

Design and protocol for a cluster randomised trial of enhanced diagnostics for tuberculosis screening among people living with HIV in hospital in Malawi (CASTLE study)

BACKGROUND: People living with HIV (PLHIV) have a high risk of death if hospitalised in low-income countries. Tuberculosis has long been the leading cause of admission and death, in part due to suboptimal diagnostics. Two promising new diagnostic tools are digital chest Xray with computer-aided diagnosis (DCXR-CAD) and urine testing with Fujifilm SILVAMP LAM (FujiLAM). Neither test has been rigorously evaluated among inpatients. Test characteristics may be complementary, with FujiLAM especially sensitive for disseminated tuberculosis and DCXR-CAD especially sensitive for pulmonary tuberculosis, making combined interventions of interest. DESIGN AND METHODS: An exploratory unblinded, single site, two-arm cluster randomised controlled trial, with day of admission as the unit of randomisation. A third, smaller, integrated cohort arm (4:4:1 random allocation) contributes to understanding case-mix, but not trial outcomes. Participants are adults living with HIV not currently on TB treatment. The intervention (DCXR-CAD plus urine FujiLAM plus usual care) is compared to usual care alone. The primary outcome is proportion of participants started on tuberculosis treatment by day 56, with secondary outcomes of mortality (time to event) measured to to 56 days from enrolment, proportions with undiagnosed tuberculosis at death or hospital discharge and comparing proportions with enrolment-day tuberculosis treatment initiation. DISCUSSION: Both DCXR-CAD and FujiLAM have potential clinical utility and may have complementary diagnostic performance. To our knowledge, this is the first randomised trial to evaluate these tests among hospitalised PLHIV