Maximum likelihood estimation for rician distributed data in analytical q-ball imaging

Analytical q-ball imaging is widely used for reconstruction of orientation distribution function (ODF) using diffusion weighted MRI data. Estimating the spherical harmonic coefficients is a critical step in this method. Least squares (LS) is widely used for this purpose assuming the noise to be additive Gaussian. However, Rician noise is considered as a more appropriate model to describe noise in MR signal. Therefore, the current estimation techniques are valid only for high SNRs with Gaussian distribution approximating the Rician distribution. The aim of this study is to present an estimation approach considering the actual distribution of the data to provide reliable results particularly for the case of low SNR values. Maximum likelihood (ML) is investigated as a more effective estimation method. However, no closed form estimator is presented as the estimator becomes nonlinear for the noise assumption of the Rician distribution. Consequently, the results of LS estimator is used as an initial guess and the more refined answer is achieved using iterative numerical methods. According to the results, the ODFs reconstructed from low SNR data are in close agreement with ODFs reconstructed from high SNRs when Rician distribution is considered. Also, the error between the estimated and actual fiber orientations was compared using ML and LS estimator. In low SNRs, ML estimator achieves less error compared to the LS estimator.

Comparison of different maximum safe levels in fortified foods and supplements using a probabilistic risk assessment approach

Different European institutions have developed mathematical models to propose maximum safe levels either for fortified foods or for dietary supplements. The objective of the present study was to compare and check the safety of these different maximum safe levels (MSL) by using a probabilistic risk assessment approach. The potential maximum nutritional intakes were estimated by taking into account all sources of intakes (base diet, fortified foods and dietary supplements) and compared with the tolerable upper intake levels for vitamins and minerals. This approach simulated the consequences of both food fortification and supplementation in terms of food safety. Different scenarios were tested. They are the result of the combination of several MSL obtained using the previous models. The study was based on the second French Individual and National Study on Food Consumption performed in 2006–7, matched with the French food nutritional composition database. The analyses were based on a sample of 1918 adults aged 18–79 years. Some MSL in fortified foods and dietary supplements obtained independently were protective enough, although some others could lead to nutritional intakes above the tolerable upper intake levels. The simulation showed that it is crucial to consider the inter-individual variability of fortified food intakes when setting MSL for foods and supplements. The risk assessment approach developed here by integrating the MSL for fortified foods and dietary supplements is useful for ensuring consumer protection. It may be subsequently used to test any other MSL for vitamins and minerals proposed in the future.

(Un)safe routes : maternal mortality and Ethiopia's development agenda

This study juxtaposed women's experiences of birth at home in rural Ethiopia where it is 'safe' with that in a modern health care setting where it is 'unsafe' because the distance from international maternal health policy to its implementation is vast and the 'pathway to maternal survival' can be circuitous.

Emerging technology for remote IED render safe using the OzBot

The Centre for Intelligent Systems Research (CISR) based within Deakin University’s Geelong campus has been developing technology specifically for remote render-safe of IED since being awarded a CTD contact in 2006. During this time, research engineers have worked with key defence and industry stakeholders to develop a series of robotic platforms tasked with immersing a soldier in his or her remote environment. Utilising Haptics (force feedback technology), stereovision (binocular video stream for depth perception) and intuitive user controls, the robots have been engineered to deliver maximum effectiveness while allowing minimal training liability. In Victoria, CISR’s OzBot series of mobile platforms have been used by the Victorian Police in a first-responder capacity, exploiting the 30-sec system boot-up and man-portable design to get eyes-on-target at the soonest possible moment. The CISR robotics group has been working on technologies that reduce operator fatigue, minimise training liability and maintenance, developing simulation technologies for increased training availability and develop mobile platforms with increased range, payload, manipulator reach and capability. This paper describes some of the technologies, methods and systems developed by CISR in the field of IED neutralisation with the aim of increasing military awareness of Australian capability.

N-Acetyl cysteine as a glutathione precursor for schizophrenia : a double blind, randomized, placebo-controlled trial

Background: Brain glutathione levels are decreased in schizophrenia, a disorder that often is chronic and refractory to treatment. N-acetyl cysteine (NAC) increases brain glutathione in rodents. This study was conducted to evaluate the safety and effectiveness of oral NAC (1 g orally twice daily [b.i.d.]) as an add-on to maintenance medication for the treatment of chronic schizophrenia over a 24-week period.

Methods: A randomized, multicenter, double-blind, placebo-controlled study. The primary readout was change from baseline on the Positive and Negative Symptoms Scale (PANSS) and its components. Secondary readouts included the Clinical Global Impression (CGI) Severity and Improvement scales, as well as general functioning and extrapyramidal rating scales. Changes following a 4-week treatment discontinuation were evaluated. One hundred forty people with chronic schizophrenia on maintenance antipsychotic medication were randomized; 84 completed treatment.

Results: Intent-to-treat analysis revealed that subjects treated with NAC improved more than placebo-treated subjects over the study period in PANSS total [5.97 (10.44, 1.51), p .009], PANSS negative [mean difference 1.83 (95% confidence interval: 3.33, .32), p .018], and PANSS general [2.79 (5.38, .20), p .035], CGI-Severity (CGI-S) [.26 (.44,.08), p .004], and CGI-Improvement (CGI-I) [.22 (.41, .03), p .025] scores. No significant change on the PANSS positive subscale was seen. N-acetyl cysteine treatment also was associated with an improvement in akathisia (p .022). Effect sizes at end point were consistent with moderate benefits.

Conclusions: These data suggest that adjunctive NAC has potential as a safe and moderately effective augmentation strategy for chronic schizophrenia.

Monitoring the safe use of Clozapine : a consensus view from Victoria, Australia

Clozapine is an important antipsychotic agent that has a unique profile of clinical benefits, but that has also been associated with several serious and potentially life-threatening safety concerns. In order to minimise the impact of haematological adverse events, health professionals treating patients with clozapine are currently required to register their patients on a centrally administered data network and to conform to strict protocols. The consensus statement documented in this article extends existing protocols by recommending monitoring of patients treated with clozapine for additional adverse effects during treatment. This consensus statement reflects the current practice at five major public psychiatric hospitals in Victoria, Australia, for the monitoring and management of clozapine-related adverse events, and has been implemented at these sites because of emerging safety concerns associating clozapine with cardiovascular and metabolic adverse effects.

Maximum-likelihood based estimation for Q-ball imaging using diffusion-weighted MRI data

Q-ball imaging has been presented to reconstruct diffusion orientation distribution function using diffusion weighted MRI. In this thesiis, we present a novel and robust approach to satisfy the smoothness constraint required in Q-ball imaging. Moreover, we developed an improved estimator based on the actual distribution of the MR data.