Convex recovery of tensors using nuclear norm penalization

The subdifferential of convex functions of the singular spectrum of real matrices has been widely studied in matrix analysis, optimization and automatic control theory. Convex analysis and optimization over spaces of tensors is now gaining much interest due to its potential applications to signal processing, statistics and engineering. The goal of this paper is to present an applications to the problem of low rank tensor recovery based on linear random measurement by extending the results of Tropp to the tensors setting.Comment: To appear in proceedings LVA/ICA 2015 at Czech Republi

Dying in the margins : understanding the needs and capacities of a lower socioeconomic population for end of life care

University of Technology, Sydney. Faculty of Health.Increased disease burden and unmet health care needs are defining features of lower socioeconomic groups, both in Australia and internationally. In Australia, there is limited understanding of the needs of lower socioeconomic groups for end of life care. At the end-of-life, health disparities are often more pronounced for both patients and their caregivers. Globally, there has been scant attention on the needs of individuals from socially and economically disadvantaged groups at the end-of-life. As gaps between the rich and poor widen and the emphasis on community-based care increases, this research area is of growing significance. The research objectives of this study were to (i) provide a snapshot of the impact of socioeconomic status on place of death and after-hours crisis service utilisation by comparing outcomes of areas of high and low disadvantage; (ii) explore and describe the socioeconomic demographics, needs, capacities and experiences of patients and/or carers from a disadvantaged area focussing on (ii a) the social, economic and care outcomes and capacities at individual, community and government levels, (ii b) the nature and impact of social capital outcomes, (ii c) the experience of access for a specialist palliative care service; and (iii) describe the appropriateness, acceptability, and feasibility of self-report tools for capturing wellbeing, consumption, health literacy, social capital and palliative care needs and capacities in this population. This study used a concurrent embedded mixed method design with a qualitative emphasis and explicit use of social determinants of health framework and social capital concepts. The conceptual framework determined selection of self-report tools which additionally structured interviews. Integration of the quantitative and qualitative data was achieved through the study design, data collection and discussion. Four years of administrative data from a single palliative care service, located in a socioeconomically disadvantaged area was collected and analysed. Place of death and after-hours crisis service data were compared for a most and a least disadvantaged area compared over a twelve month period. Semi-structured interviews were conducted with 14 patients and/or carers from a lower socioeconomic area and five key informants who provided formal care for this group. Demographic data and outcomes of self-report tools were collected from patient and carer participants during interviews. Semi-structured interview responses to self-report tools were evaluated for appropriateness, acceptability and feasibility of these measures. The findings demonstrate that a lower socioeconomic group experienced end of life care within margins of social and economic resources and care networks. Social margins were shaped by limited community trust, engagement and deficiencies in social policy (public housing). Economic margins reflected income loss, healthcare spending on co-payments and economic disparity in aged care facility access. Care network margins were defined by limited informal and formal care support. Patients from the disadvantaged area had fewer home deaths and greater home care needs warranting facility admission. Capacities within the end of life care experience were demonstrated by trust and engagement with government organisations, potential for community club, neighbourhood and friendship support, access to financial support programs and benefits, and examples of supported home care networks. Recommendations for research, clinical practice and policy to address these issues are discussed. This thesis has provided a unique and novel contribution to the literature. Specifically, it has demonstrated the needs and capacities for a lower socioeconomic group not previously described in the Australian literature, and in particular, it has advanced conceptual and theoretical issues in investigating social and economic issues in end-of-life care

Helminth species richness in wild wood mice, Apodemus sylvaticus, is enhanced by the presence of the intestinal nematode Heligmosomoides polygyrus

We analysed 3 independently collected datasets of fully censused helminth burdens in wood mice, Apodemus sylvaticus, testing the a priori hypothesis of Behnke et al. (2005) that the presence of the intestinal nematode Heligmosomoides polygyrus predisposes wood mice to carrying other species of helminths. In Portugal, mice carrying H. polygyrus showed a higher prevalence of other helminths but the magnitude of the effect was seasonal. In Egham, mice with H. polygyrus showed a higher prevalence of other helminth species, not confounded by other factors. In Malham Tarn, mice carrying H. polygyrus were more likely to be infected with other species, but only among older mice. Allowing for other factors, heavy residual H. polygyrus infections carried more species of other helminths in both the Portugal and Egham data; species richness in Malham was too low to conduct a similar analysis, but as H. polygyrus worm burdens increased, so the prevalence of other helminths also increased. Our results support those of Behnke et al. (2005), providing firm evidence that at the level of species richness a highly predictable element of co-infections in wood mice has now been defined: infection with H. polygyrus has detectable consequences for the susceptibility of wood mice to other intestinal helminth species

Dying in the margins: Understanding palliative care and socioeconomic deprivation in the developed world

Context: Individuals from low socioeconomic (SE) groups have less resources and poorer health outcomes. Understanding the nature of access to appropriate end-of-life care services for this group is important. Objectives: To evaluate the literature in the developed world for barriers to access for low SE groups. Methods: Electronic databases searched in the review included MEDLINE (1996-2010), CINAHL (1996-2010), PsychINFO (2000-2010), Cochrane Library (2010), and EMBASE (1996-2010). Publications were searched for key terms "socioeconomic disadvantage," "socioeconomic," "poverty," "poor" paired with "end-of-life care," "palliative care," "dying," and "terminal Illness." Articles were analyzed using existing descriptions for dimensions of access to health services, which include availability, affordability, acceptability, and geographical access. Results: A total of 67 articles were identified for the literature review. Literature describing end-of-life care and low SE status was limited. Findings from the review were summarized under the headings for dimensions of access. Conclusion: Low SE groups experience barriers to access in palliative care services. Identification and evaluation of interventions aimed at reducing this disparity is required. © 2011 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved

Inferring Population Preferences via Mixtures of Spatial Voting Models

Understanding political phenomena requires measuring the political preferences of society. We introduce a model based on mixtures of spatial voting models that infers the underlying distribution of political preferences of voters with only voting records of the population and political positions of candidates in an election. Beyond offering a cost-effective alternative to surveys, this method projects the political preferences of voters and candidates into a shared latent preference space. This projection allows us to directly compare the preferences of the two groups, which is desirable for political science but difficult with traditional survey methods. After validating the aggregated-level inferences of this model against results of related work and on simple prediction tasks, we apply the model to better understand the phenomenon of political polarization in the Texas, New York, and Ohio electorates. Taken at face value, inferences drawn from our model indicate that the electorates in these states may be less bimodal than the distribution of candidates, but that the electorates are comparatively more extreme in their variance. We conclude with a discussion of limitations of our method and potential future directions for research.Comment: To be published in the 8th International Conference on Social Informatics (SocInfo) 201

Parameterized lower bound and NP-completeness of some HH-free Edge Deletion problems

For a graph $H$, the $H$-free Edge Deletion problem asks whether there exist at most $k$ edges whose deletion from the input graph $G$ results in a graph without any induced copy of $H$. We prove that $H$-free Edge Deletion is NP-complete if $H$ is a graph with at least two edges and $H$ has a component with maximum number of vertices which is a tree or a regular graph. Furthermore, we obtain that these NP-complete problems cannot be solved in parameterized subexponential time, i.e., in time $2^{o(k)}\cdot |G|^{O(1)}$, unless Exponential Time Hypothesis fails.Comment: 15 pages, COCOA 15 accepted pape

Unit Interval Editing is Fixed-Parameter Tractable

Given a graph~$G$ and integers $k_1$, $k_2$, and~$k_3$, the unit interval editing problem asks whether $G$ can be transformed into a unit interval graph by at most $k_1$ vertex deletions, $k_2$ edge deletions, and $k_3$ edge additions. We give an algorithm solving this problem in time $2^{O(k\log k)}\cdot (n+m)$, where $k := k_1 + k_2 + k_3$, and $n, m$ denote respectively the numbers of vertices and edges of $G$. Therefore, it is fixed-parameter tractable parameterized by the total number of allowed operations. Our algorithm implies the fixed-parameter tractability of the unit interval edge deletion problem, for which we also present a more efficient algorithm running in time $O(4^k \cdot (n + m))$. Another result is an $O(6^k \cdot (n + m))$-time algorithm for the unit interval vertex deletion problem, significantly improving the algorithm of van 't Hof and Villanger, which runs in time $O(6^k \cdot n^6)$.Comment: An extended abstract of this paper has appeared in the proceedings of ICALP 2015. Update: The proof of Lemma 4.2 has been completely rewritten; an appendix is provided for a brief overview of related graph classe

Using EEG spatial correlation, cross frequency energy, and wavelet coefficients for the prediction of Freezing of Gait in Parkinson's Disease patients

Parkinson's Disease (PD) patients with Freezing of Gait (FOG) often experience sudden and unpredictable failure in their ability to start or continue walking, making it potentially a dangerous symptom. Emerging knowledge about brain connectivity is leading to new insights into the pathophysiology of FOG and has suggested that electroencephalogram (EEG) may offer a novel technique for understanding and predicting FOG. In this study we have integrated spatial, spectral, and temporal features of the EEG signals utilizing wavelet coefficients as our input for the Multilayer Perceptron Neural Network and k-Nearest Neighbor classifier. This approach allowed us to predict transition from walking to freezing with 87 % sensitivity and 73 % accuracy. This preliminary data affirms the functional breakdown between areas in the brain during FOG and suggests that EEG offers potential as a therapeutic strategy in advanced PD. © 2013 IEEE

Adolescent over-general memory, life events and mental health outcomes: Findings from a UK cohort study

Previous research suggesting that over-general memory (OGM) may moderate the effect of life events on depressive symptoms and suicidality has sampled older adolescents or adults, or younger adolescents in high-risk populations, and has been conducted over relatively short follow-up periods. The authors examined the relationship between OGM at age 13 and life events and mental health outcomes (depression, self-harm, suicidal ideation and planning) at age 16 years within a sample of 5792 adolescents participating in the Avon Longitudinal Study of Parents and Children (ALSPAC), approximately 3800 of whom had also provided data on depression and self-harm. There was no clear evidence of either direct or interactive effects of OGM at age 13 on levels of depression at age 16. Similarly there was no clear evidence of either direct or interactive effects of OGM on suicidal ideation and self-harm. Although there was some evidence that over-general autobiographical memory was associated with reduced risk of suicidal planning and increased risk of self-harm, these associations were absent when confounding variables were taken into account. The findings imply that although OGM is a marker of vulnerability to depression and related psychopathology in high-risk groups, this cannot be assumed to generalise to whole populations