Solution of Linear Programming Problems using a Neural Network with Non-Linear Feedback

This paper presents a recurrent neural circuit for solving linear programming problems. The objective is to minimize a linear cost function subject to linear constraints. The proposed circuit employs non-linear feedback, in the form of unipolar comparators, to introduce transcendental terms in the energy function ensuring fast convergence to the solution. The proof of validity of the energy function is also provided. The hardware complexity of the proposed circuit compares favorably with other proposed circuits for the same task. PSPICE simulation results are presented for a chosen optimization problem and are found to agree with the algebraic solution. Hardware test results for a 2–variable problem further serve to strengthen the proposed theory

Maximum tolerable dose of cyclophosphamide and azathioprine in Pakistani patients with primary renal disease

Objective: The immunosuppressive regimens, at present, mainly rely on western guidelines that were derived from studies conducted in western populations. No such study exists for South Asian population, which is home to almost two billion people different in both genetics and environment from west. Locally derived thresholds for side effects markedly different from western figures may warrant re-adjustment of current local immunosuppressive regimens that are at present based largely on western guidelines. In order to define optimum dose for Cyclophosphamide (CYC) and Azathioprine (AZA) based immunosuppressive therapy, we conducted this study to find out maximum tolerable doses of azathioprine (AZA) and cyclophosphamide (CYC) beyond which neutropenia and thrombocytepenia are most likely to occur in patients with primary renal pathology.METHOD: Patients with systemic vasculitis and idiopathic glomerulonephritis who were on CYC and AZA were identified through review of medical records at a tertiary care hospital in Pakistan (The Aga Khan University Hospital, Karachi). Patients were categorized under three principal diagnosis i.e. systemic lupus erythematosus (SLE), primary (idiopathic) glomerulonephritis (GN) and Wegener\u27s granulomatosis (WG). The Receiver Operating Curve (ROC) was used to calculate the maximum tolerable dose for both CYC and AZA.Results: We identified 94 patients aged 6-82 years (median 44.5 years) with primary renal disease (Wegener\u27s granulomatosis n=13, Systemic lupus erythematosis n=62 and idiopathic glomerulonephritis n=19) who received CYC or AZA. Of these 94 patients, 36.2% (n=34) received CYC and 63.8% (n=60) received AZA. The mean dose of CYC was 1.54 +/- 0.50 mg/kg of body weight (range: 0.77-2.93). The mean dose of AZA was 1.64 +/- 0.59 mg/kg of body weight (range: 0.47-2.97). The maximum tolerable doses calculated for CYC and AZA were 1.25 mg/kg and 1.30 mg/kg of body weight respectively. The maximum tolerable dose for CYC and AZA among males could not be calculated, because of insufficient number of patients who developed neutropenia and thrombocytopenia. The maximum tolerable doses for CYC and AZA among females were 1.34 mg/kg and 1.03 mg/kg of body weight respectively. Also we found out that AZA was relatively more likely to cause neutropenia and thrombocytopenia (p=0.07).CONCLUSION: We thereby recommend that CYC should be initiated at a dose no more than 1 mg/kg of body weight and AZA at an initial dose of 0.75-1.0 mg/kg of body weight. The dose may be adjusted later on the basis of clinical response and laboratory reports

A decision tool for radiographer-led abdominal image-guided stereotactic ablative body radiotherapy – Experience from a single institution

A decision tool for radiographer-led image-guided radiotherapy (IGRT) using cone-beam CT (CBCT) for abdominal stereotactic radiotherapy was developed and successfully implemented in a single department. The confidence of 7 therapeutic radiographers when undertaking online CBCT review increased, and the pooled median online match time was reduced by 1 m 8 s. While this may be advantageous for abdominal SABR, further evaluation of this work in a larger cohort is required to validate these results

Ever-increasing Caesarean section and its economic burden in Bangladesh

BACKGROUND: Cesarean Section (CS) delivery has been increasing rapidly worldwide and Bangladesh is no exception. In Bangladesh, the CS rate has increased from about 3% in 2000 to about 24% in 2014. This study examines trend in CS in Bangladesh over the last fifteen years and implications of this increasing CS rates on health care expenditures. METHODS: Birth data from Bangladesh Demographic and Health Survey (BDHS) for the years 2000–2014 have been used for the trend analysis and 2010 Bangladesh Maternal Mortality Survey (BMMS) data were used for estimating health care expenditure associated with CS. RESULTS: Although the share of institutional deliveries increased four times over the years 2000 to 2014, the CS deliveries increased eightfold. In 2000, only 33% of institutional deliveries were conducted through CS and the rate increased to 63% in 2014. Average medical care expenditure for a CS delivery in Bangladesh was about BDT 22,085 (USD 276) in 2010 while the cost of a normal delivery was BDT 3,565 (USD 45). Health care expenditure due to CS deliveries accounted for about 66.5% of total expenditure on all deliveries in Bangladesh in 2010. About 10.3% of Total Health Expenditure (THE) in 2010 was due to delivery costs, while CS costs contribute to 6.9% of THE and rapid increase in CS deliveries will mean that delivering babies will represent even a higher proportion of THE in the future despite declining crude birth rate. CONCLUSION: High CS delivery rate and the negative health outcomes associated with the procedure on mothers and child births incur huge economic burden on the families. This is creating inappropriate allocation of scarce resources in the poor economy like Bangladesh. Therefore it is important to control this unnecessary CS practices by the health providers by introducing litigation and special guidelines in the health policy

Radiopaque drug-eluting embolisation beads as fiducial markers for stereotactic liver radiotherapy

OBJECTIVE: To determine the feasibility of using radiopaque (RO) beads as direct tumour surrogates for image-guided radiotherapy (IGRT) in patients with liver tumours after transarterial chemoembolisation (TACE). METHODS: A novel vandetanib-eluting RO bead was delivered via TACE as part of a first-in-human clinical trial in patients with either hepatocellular carcinoma or liver metastases from colorectal cancer. Following TACE, patients underwent simulated radiotherapy imaging with 4-dimensional computed tomography (4D-CT) and cone-beam CT (CBCT) imaging. RO beads were contoured using automated thresholding, and feasibility of matching between the simulated radiotherapy planning dataset (AVE-IP image from 4D data) and CBCT scans assessed. Additional kV, MV, helical CT and CBCT images of RO beads were obtained using an in-house phantom. Stability of RO bead position was assessed by comparing 4D-CT imaging to CT scans taken 6-20 days following TACE. RESULTS: Eight patients were treated and 4D-CT and CBCT images acquired. RO beads were visible on 4D-CT and CBCT images in all cases and matching successfully performed. Differences in centre of mass of RO beads between CBCT and simulated radiotherapy planning scans (AVE-IP dataset) were: 2.0 mm mediolaterally, 1.7 mm anteroposteriorally, 3.5 mm craniocaudally. RO beads in the phantom were visible on all imaging modalities assessed. RO bead position remained stable up to 29 days post-TACE. CONCLUSION: RO beads are visible on IGRT imaging modalities, showing minimal artefact. They can be used for on-set matching with CBCT and remain stable over time. ADVANCES IN KNOWLEDGE: The role of RO beads as fiducial markers for stereotactic liver radiotherapy is feasible and warrants further exploration as a combination therapy approach

Atlas construction and spatial normalisation to facilitate radiation-induced late effects research in childhood cancer

Reducing radiation-induced side effects is one of the most important challenges in paediatric cancer treatment. Recently, there has been growing interest in using spatial normalisation to enable voxel-based analysis of radiation-induced toxicities in a variety of patient groups. The need to consider three-dimensional distribution of doses, rather than dose-volume histograms, is desirable but not yet explored in paediatric populations. In this paper, we investigate the feasibility of atlas construction and spatial normalisation in paediatric radiotherapy. We used planning computed tomography (CT) scans from twenty paediatric patients historically treated with craniospinal irradiation to generate a template CT that is suitable for spatial normalisation. This childhood cancer population representative template was constructed using groupwise image registration. An independent set of 53 subjects from a variety of childhood malignancies was then used to assess the quality of the propagation of new subjects to this common reference space using deformable image registration (i.e., spatial normalisation). The method was evaluated in terms of overall image similarity metrics, contour similarity and preservation of dose-volume properties. After spatial normalisation, we report a dice similarity coefficient of 0.95±0.05, 0.85±0.04, 0.96±0.01, 0.91±0.03, 0.83±0.06 and 0.65±0.16 for brain and spinal canal, ocular globes, lungs, liver, kidneys and bladder. We then demonstrated the potential advantages of an atlas-based approach to study the risk of second malignant neoplasms after radiotherapy. Our findings indicate satisfactory mapping between a heterogeneous group of patients and the template CT. The poorest performance was for organs in the abdominal and pelvic region, likely due to respiratory and physiological motion and to the highly deformable nature of abdominal organs. More specialised algorithms should be explored in the future to improve mapping in these regions. This study is the first step toward voxel-based analysis in radiation-induced toxicities following paediatric radiotherapy

Corrosion behavior of electrodeposited Ni-B coatings modified with SiO2 particles

The need for coatings with improved operation is vital to insure safety and high output of industrial plants. Electrodeposition is a valuable surface modification technology that can be used to develop various kinds of coatings. Although, Ni-B coatings have good mechanical properties (hardness and wear) but are suffering from inferior corrosion resistance. The development of Ni-B composite coatings by incorporating insoluble hard particles such as metal oxides (Al2O3, TiO2 ) through electrodeposition process has generated a great interest among the research community because of auspicious improvement in properties. The main purpose of this research work was to study the influence of addition of SiO2 particles on corrosion performance of Ni-B coated surfaces which has not been reported so far. Coatings of Ni-B and Ni-B-SiO2 were deposited on steel through electrodeposition process. The microstructural (SEM) analysis confirms the formation of uniform, dense nodular structure in coatings of Ni-B and Ni-B-SiO2 . Surface examination (AFM) discloses that the addition of SiO2 increases surface smoothness. Electrochemical characterization of the synthesized coatings indicates that Ni-B-SiO2 composite coatings demonstrate better anticorrosion properties when compared to Ni-B. Enhanced corrosion performance may be ascribed to reduction in the active surface area and grain size refinement which reduces the porosity by the addition of inactive SiO2 particles.Scopu