Adaptive Seeding for Gaussian Mixture Models

We present new initialization methods for the expectation-maximization algorithm for multivariate Gaussian mixture models. Our methods are adaptions of the well-known $K$-means++ initialization and the Gonzalez algorithm. Thereby we aim to close the gap between simple random, e.g. uniform, and complex methods, that crucially depend on the right choice of hyperparameters. Our extensive experiments indicate the usefulness of our methods compared to common techniques and methods, which e.g. apply the original $K$-means++ and Gonzalez directly, with respect to artificial as well as real-world data sets.Comment: This is a preprint of a paper that has been accepted for publication in the Proceedings of the 20th Pacific Asia Conference on Knowledge Discovery and Data Mining (PAKDD) 2016. The final publication is available at link.springer.com (http://link.springer.com/chapter/10.1007/978-3-319-31750-2 24

On Kaluza's sign criterion for reciprocal power series

T. Kaluza has given a criterion for the signs of the power series of a function that is the reciprocal of another power series. In this note the sharpness of this condition is explored and various examples in terms of the Gaussian hypergeometric series are given. A criterion for the monotonicity of the quotient of two power series due to M. Biernacki and J. Krzy\.z is applied.Comment: 13 page

Reconstructing ‘the Alcoholic’: Recovering from Alcohol Addiction and the Stigma this Entails

Public perception of alcohol addiction is frequently negative, whilst an important part of recovery is the construction of a positive sense of self. In order to explore how this might be achieved, we investigated how those who self-identify as in recovery from alcohol problems view themselves and their difficulties with alcohol and how they make sense of others’ responses to their addiction. Semi-structured interviews with six individuals who had been in recovery between 5 and 35 years and in contact with Alcoholics Anonymous were analysed using Interpretative Phenomenological Analysis. The participants were acutely aware of stigmatising images of ‘alcoholics’ and described having struggled with a considerable dilemma in accepting this identity themselves. However, to some extent they were able to resist stigma by conceiving of an ‘aware alcoholic self’ which was divorced from their previously unaware self and formed the basis for a new more knowing and valued identity

Surface relaxation and ferromagnetism of Rh(001)

The significant discrepancy between first-principles calculations and experimental analyses for the relaxation of the (001) surface of rhodium has been a puzzle for some years. In this paper we present density functional theory calculations using the local-density approximation and the generalized gradient approximation of the exchange-correlation functional. We investigate the thermal expansion of the surface and the possibility of surface magnetism. The results throw light on several, hitherto overlooked, aspects of metal surfaces. We find, that, when the free energy is considered, density-functional theory provides results in good agreement with experiments.Comment: 6 pages, 4 figures, submitted to Phys. Rev. Lett. (April 28, 1996

Effect of gas phase on SiC and Si 3 N 4 formations from SiO 2

During the synthesis of SiC, Si 3 N 4 and sialon whiskers by carbothermal reduction of SiO 2 , a localized formation of amorphous phases or Si 2 N 2 O powders was observed beneath these whiskers. Because these whiskers were formed by the vapour/solid mechanism, the controlling gas phase was of primary importance to obtain whiskers of tailored morphology and chemistry. To elucidate the effect of the gas phase composition on the reaction mechanisms of SiC and Si 3 N 4 , the oxygen partial pressure was measured during the synthesis with a ZrO 2 solid electrolyte. The carbothermal reduction of SiO 2 , as well as evolution of gases, were accelerated by a formation of a molten fluorosilicate with an auxiliary halide bath. The oxygen partial pressure steadily increased with increasing temperature and reached a maximum level of 10 −11 10 −12 atm in the early stage of reaction at 1623 K, then decreased again towards the end of reaction in both cases. Effects of the gas phase on the SiC and Si 3 N 4 formations were not the same: p CO and and their ratio were important factors in the SiC formation, while the higher formed an oxynitride phase in the Si 3 N 4 formation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44719/1/10853_2004_Article_BF00542914.pd

“<i>I do it because they do it</i>”:social-neutralisation in information security practices of Saudi medical interns

Successful implementation of information security policies (ISP) and IT controls play an important role in safeguarding patient privacy in healthcare organizations. Our study investigates the factors that lead to healthcare practitioners' neutralisation of ISPs, leading to non-compliance. The study adopted a qualitative approach and conducted a series of semi-structured interviews with medical interns and hospital IT department managers and staff in an academic hospital in Saudi Arabia. The study's findings revealed that the MIs imitate their peers' actions and employ similar justifications when violating ISP dictates. Moreover, MI team superiors' (seniors) ISP non-compliance influence MIs tendency to invoke neutralisation techniques. We found that the trust between the medical team members is an essential social facilitator that motivates MIs to invoke neutralisation techniques to justify violating ISP policies and controls. These findings add new insights that help us to understand the relationship between the social context and neutralisation theory in triggering ISP non-compliance

Hypoxia regulates human lung fibroblast proliferation via p53-dependent and -independent pathways

<p>Abstract</p> <p>Background</p> <p>Hypoxia induces the proliferation of lung fibroblasts in vivo and in vitro. However, the subcellular interactions between hypoxia and expression of tumor suppressor p53 and cyclin-dependent kinase inhibitors p21 and p27 remain unclear.</p> <p>Methods</p> <p>Normal human lung fibroblasts (NHLF) were cultured in a hypoxic chamber or exposed to desferroxamine (DFX). DNA synthesis was measured using bromodeoxyuridine incorporation, and expression of p53, p21 and p27 was measured using real-time RT-PCR and Western blot analysis.</p> <p>Results</p> <p>DNA synthesis was increased by moderate hypoxia (2% oxygen) but was decreased by severe hypoxia (0.1% oxygen) and DFX. Moderate hypoxia decreased p21 synthesis without affecting p53 synthesis, whereas severe hypoxia and DFX increased synthesis of both p21 and p53. p27 protein expression was decreased by severe hypoxia and DFX. Gene silencing of p21 and p27 promoted DNA synthesis at ambient oxygen concentrations. p21 and p53 gene silencing lessened the decrease in DNA synthesis due to severe hypoxia or DFX exposure. p21 gene silencing prevented increased DNA synthesis in moderate hypoxia. p27 protein expression was significantly increased by p53 gene silencing, and was decreased by wild-type p53 gene transfection.</p> <p>Conclusion</p> <p>These results indicate that in NHLF, severe hypoxia leads to cell cycle arrest via the p53-p21 pathway, but that moderate hypoxia enhances cell proliferation via the p21 pathway in a p53-independent manner. In addition, our results suggest that p27 may be involved in compensating for p53 in cultured NHLF proliferation.</p

Exploring the potential of civic engagement to strengthen mental health systems in Indonesia (IGNITE) : a study protocol

Background Indonesia has the highest rate of years of life lost to disability or early death from Schizophrenia than any other country in the world. More than 90% of people with mental illness do not get any treatment and tens of thousands of people with psychosis are illegally detained ('pasung') in the family home. Civic engagement, a core part of the recent World Health Organisation global strategy, has the potential to address some of these challenges through the development of person-centered models of care. The aim of the study is to develop a testable systems level, culturally appropriate, civic engagement framework for use in Jakarta and Bogor, Indonesia to strengthen local mental health services. Methods A mixed methods study underpinned by a realist approach will be undertaken across four phases in two study sites in Indonesia (Jakarta and Bogor). Phase 1 will explore the use of civic engagement across South East Asia by conducting a systematic review of existing evidence. By surveying 300 mental health professionals, phase 2 will identify the stakeholders, the sources of collaboration and the evidence used by professionals in decision making within local mental health systems and identify potential opportunities for civic engagement within the system. In order to explore the potential use of civic engagement within Indonesian mental health services and identify priorities for a culturally appropriate framework, phase 3 will undertake two focus groups with participants with experience of psychosis or caring for someone with psychosis (n = 20–30). Professionals and other key decision makers in a range of roles across the system at a national (n = 5) and local level (n = 10–15/site) will also take part in semi-structured interviews. Phase 4 will co-produce a civic engagement framework for use in Indonesia by synthesising evidence from phases 1–3 collaboratively with key stakeholders. Discussion Civic engagement is a potential way in which health services in low and middle income countries can address the burden of mental health conditions through the development of person-centred models of care. However, such approaches are underexplored in Indonesia. This study will work with local stakeholders to design a testable civic engagement framework for use in mental health services in Indonesia

Business angel exits: A theory of planned behaviour perspective

Although there are a handful of studies on business angel investment returns, the business angel literature has given little or no attention to exits and the exit strategy. This is surprising given that a primary objective of investing is to achieve a capital gain through some form of liquidity event. Using the theory of planned behaviour (TPB) as an interpretative heuristic, we examine how exits happen: specifically, what are the motivations to seek an exit and to what extent are they planned or opportunistic? Based on multiple case studies in which business angels were invited to tell the story of their most recent exit(s), the evidence suggests that the majority of liquidity events are the outcome of planned behaviour. We propose a typology of angel-backed investment exits as the basis for identifying future directions for research and developing practical advice to angels on effective business practices