Mixing Matrix Estimation From Sparse Mixtures With Unknown Number of Sources

In blind source separation, many methods have been proposed to estimate the mixing matrix by exploiting sparsity. However, they often need to know the source number a priori, which is very inconvenient in practice. In this paper, a new method, namely nonlinear projection and column masking (NPCM), is proposed to estimate the mixing matrix. A major advantage of NPCM is that it does not need any knowledge of the source number. In NPCM, the objective function is based on a nonlinear projection and its maxima just correspond to the columns of the mixing matrix. Thus a column can be estimated first by locating a maximum and then deflated by a masking operation. This procedure is repeated until the evaluation of the objective function decreases to zero dramatically. Thus the mixing matrix and the number of sources are estimated simultaneously. Because the masking procedure may result in some small and useless local maxima, particle swarm optimization (PSO) is introduced to optimize the objective function. Feasibility and efficiency of PSO are also discussed. Comparative experimental results show the efficiency of NPCM, especially in the cases where the number of sources is unknown and the sources are relatively less sparse.

Association of early childhood abdominal circumference and weight gain with blood pressure at 36 months of age: secondary analysis of data from a prospective cohort study

To assess whether changes in measures of fat distribution and body size during early life are associated with blood pressure at 36 months of age.

Substantial reductions in the number of diabetic ketoacidosis and severe hypoglycaemia episodes requiring emergency treatment lead to reduced costs after structured education in adults with Type 1 diabetes

To determine the impact of structured education promoting flexible intensive insulin therapy on rates of diabetic ketoacidosis, and the costs associated with emergency treatment for severe hypoglycaemia and ketoacidosis in adults with Type 1 diabetes.

Neural signal analysis by landmark-based spectral clustering with estimated number of clusters

Spike sorting plays an important role in analysing electrophysiological data and understanding neural functions. Developing spike sorting methods that are highly accurate and computationally inexpensive is always a challenge in the biomedical engineering practice. This paper proposes an automatic unsupervised spike sorting method using the landmark-based spectral clustering (LSC) method in connection with features extracted by the locality preserving projection (LPP) technique. Gap statistics is employed to evaluate the number of clusters before the LSC can be performed. Experimental results show that LPP spike features are more discriminative than those of the popular wavelet transformation (WT). Accordingly, the proposed method LPP-LSC demonstrates a significant dominance compared to the existing method that is the combination between WT feature extraction and the superparamagnetic clustering. LPP and LSC are both linear algorithms that help reduce computational burden and thus their combination can be applied into realtime spike analysis.

Food security: one of a number of ‘securities’ we need for a full life: an Australian perspective

Although agriculture in Australia is very productive, the current food supply systems in Australia fail to deliver healthy diets to all Australians and fail to protect the natural resources on which they depend. The operation of the food systems creates ‘collateral damage’ to the natural environment including biodiversity loss. In coming decades, Australia’s food supply systems will be increasingly challenged by resource price inflation and climate change. Australia exports more than half of its current agricultural production. Government and business are aiming to substantially increase production to bolster exports. This will increase pressure on agricultural resources and exacerbate ‘collateral’ damage to the environment. The Australian public have a deep and ongoing interest in a very wide range of issues associated with the food systems including the environment, health and sustainability. Food is something we require in order to live and a good diet is something we have to have to be healthy. For health over a life-time we need food security. However, we also require a range of other material goods and social arrangements in order to develop and flourish as human beings. And we need these other things to be secure over a life-time. Food is therefore one security among a range of other securities we need in order to flourish. The paper outlines a number of approaches, as examples, that help to identify what these other goods and arrangements might be. The approaches mentioned in this paper include human rights, national securities, human needs, authentic happiness, capabilities, sustainability and environmental ethics. The different approaches provide a way of evaluating the current situation and indicating a direction for change within the food systems that will address the problems. However, changing large systems such as those involved in food supply is difficult because inertias and vested interests make the current food supply systems resilient to change. The paper suggests that one of the first and ongoing tasks is to develop an understanding of the situation from a comprehensive social–ecological systems perspective. The paper also suggests that a practical leverage point for system change is restructuring the flow of information on the health, natural resources and biodiversity loss issues related to the food supply systems.

On the determination of the number of factors using information criteria with data-driven penalty

As is well known, when using an information criterion to select the number of common factors in factor models the appropriate penalty is generally indetermine in the sense that it can be scaled by an arbitrary constant, c say, without affecting consistency. In an influential paper, Hallin and Liška (J Am Stat Assoc102:603–617, 2007) proposes a data-driven procedure for selecting the appropriate value of c. However, by removing one source of indeterminacy, the new procedure simultaneously creates several new ones, which make for rather complicated implementation, a problem that has been largely overlooked in the literature. By providing an extensive analysis using both simulated and real data, the current paper fills this gap.

Background and context of the study

This chapter provides the necessary background and context for the study. Australia and the Gulf Cooperation Council (GCC) states have a long history of trade and investment activities between them. Trade and investment have evolved gradually over the years. However, the acceleration of globalisation and the resulting changes taking place in the structure of the world economy have led many small economies such as Australia and the GCC states to engage strategically with their trading partners in order to remain an integral part of the global economy. Australia and GCC started to negotiate a free trade agreement (FTA) in 2007 with negotiations slowing down for a number of years. Recently, Australia has shown a strong determination to conclude a successful FTA with the GCC. Such a prospect raises a number of interesting questions regarding the potential benefits of a successful Australia–GCC FTA which is the subject of this research.

Organizational factors related to the confidence of workers in working with residents with dementia or depression in aged care facilities

OBJECTIVES: There has been limited research examining how organizational factors are associated with the level of confidence of residential aged care staff in managing both residents' depression and the behavioural and psychological symptoms of residents with dementia (BPSD). This study investigated this issue. METHOD: A cross-sectional study design was employed. In total, 255 aged care staff (131 senior staff, 124 junior staff) from 21 residential care facilities participated in the study. All staff completed measures of self-efficacy in managing BPSD as well as confidence in working with older people with depression. They also completed measures of organizational climate (autonomy, cohesion, trust, pressure, support, recognition, fairness and encouragement of innovation) and measures of workplace experience (job role, number of years working in aged care facilities), job stress and satisfaction, and knowledge of depression. RESULTS: The results demonstrated that autonomy, trust, support, and job stress were associated with confidence in managing BPSD, while the factors related to confidence in managing depression were autonomy, support, job stress, job satisfaction, and knowledge of depression. CONCLUSION: These findings highlight that organizational climate factors need to be addressed in order to increase staff confidence in managing BPSD and depression. In particular, the findings demonstrate the importance of fostering organizational environments in which autonomy is promoted and there is support and cooperation among aged care staff. Attention to these factors is likely to increase the confidence of staff as they carry out their carer role.

Relative toxicity of selective serotonin reuptake inhibitors (SSRIs) in overdose

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) have increasingly replaced tricyclic antidepressants (TCAs) in the treatment of depression. They appear to be safer in overdose, but there is little information on their spectrum of toxicity in overdose, or relative toxicity of each agent. OBJECTIVE: To determine the effect of SSRIs in overdose, as a group, and the relative toxicity of five different SSRIs. METHODS: A review of consecutive SSRI poisoning admissions to a single toxicology unit. Outcomes examined were length of stay [LOS], intensive care [ICU] admission rate, coma, seizures, electrocardiographic [ECG] abnormalities, and presence of serotonin syndrome [SS]. Logistic regression was used to model the outcome QTc >440 msec. RESULTS: There were 469 SSRI poisoning admissions analyzed after exclusions. The median LOS for all SSRI overdose admissions was 15.3 h (IQR: 10.5-21.3) and 30 of 469 (6.4%; 95% CI 4.3-9.0%) cases were admitted to ICU. The incidence of seizures was 1.9% and coma was 2.4%. Serotonin syndrome occurred in 14% of overdoses. Comparison of median QTc intervals of the five SSRIs was significantly different (p=0.0002); citalopram (450 IQR: 436-484) was individually different to fluoxetine (p=0.045), fluvoxamine (p=0.022), paroxetine (p=0.0002), and sertraline (p=0.001). The proportion of citalopram overdoses with a QTc >440 msec was 68%, differing significantly from sertraline (adjusted OR: 5.11 95% CI 2.32-11.27). Comparison of median QT intervals of the five SSRIs was statistically different (p=0.026); citalopram (400 IQR: 380-440) was individually different from sertraline (p=0.023). CONCLUSIONS: This study shows SSRIs are relatively safe in overdose despite serotonin syndrome being common. The exception was citalopram, which was significantly associated with QTc prolongation. We believe that cardiac monitoring should be considered in citalopram overdose, particularly with large ingestions and patients with associated cardiac disease.