University of Western Australia

About: University of Western Australia is a education organization based out in Perth, Western Australia, Australia. It is known for research contribution in the topics: Population & Poison control. The organization has 29613 authors who have published 87405 publications receiving 3064466 citations. The organization is also known as: UWA & University of WA.

Sleep Apnea as an Independent Risk Factor for All-Cause Mortality: The Busselton Health Study

Abstract: OBSTRUCTIVE SLEEP APNEA (OSA) IS CHARACTERIZED BY REPETITIVE UPPER AIRWAY CLOSURE DURING SLEEP RESULTING IN REPEATED REVERSIBLE blood oxygen desaturation and fragmented sleep. OSA has been associated with a range of pathophysiological changes that impair cardiovascular function,1 including increased blood inflammatory markers and repeated rises in blood pressure during sleep. There is increasing evidence that OSA promotes the development of hypertension, stroke, myocardial infarction and premature death.2 However, because OSA is strongly associated with obesity and thus also with many other obesity-related diseases, it has been difficult to produce clear evidence that these associations are caused by sleep apnea and not other established causes. Better understanding of the association between OSA and mortality risk has major public health importance.3 A number of studies have shown that approximately 25% of middle-aged men and 9% of middle-aged women stop breathing during sleep ≥ 5 times per hour.4–6 Given that the major modifiable risk factor for OSA is obesity it is likely that the prevalence of OSA is increasing.7 Thus, as a very common condition, even modest effects of sleep apnea on morbidity and mortality would be important.3 Previous reports that have independently linked OSA to mortality have all been based on patients referred to sleep clinics.8–14 Two of the most recent and frequently cited of these studies indicated that severe sleep apnea, compared to no sleep apnea, was an independent risk factor for cardiovascular mortality (odds ratio 2.87, 95% CL 1.17, 7.51)12; the other study found that sleep apnea, compared to no sleep apnea, was an independent risk factor for a composite endpoint of all-cause mortality or incident stroke (hazard ratio 1.97, 95% CL 1.12, 3.48).11 However, as these were not community recruited participants they might have been subject to a clinical referral bias that might have given a false impression of the size or significance of the true association with mortality in the community. The choice of composite or restricted mortality endpoints also failed to rule out that sleep apnea might have had some unexpected beneficial effect that reduced mortality from other causes. Data from a community-based cohort, free from clinical referral bias, would thus be useful to determine whether sleep apnea is an independent risk factor for all-cause mortality in middle-aged people. The community of Busselton in Western Australia has been the subject of cross-sectional and follow-up health surveys since 1966.15–17 We aimed to investigate whether sleep apnea is an independent risk factor for all-cause mortality in a sample of Busselton Health Study participants recruited in 1990 to determine the community prevalence of sleep apnea.4

Astrophysical implications of the binary black hole merger gw150914

Abstract: The discovery of the gravitational-wave source GW150914 with the Advanced LIGO detectors provides the first observational evidence for the existence of binary black-hole systems that inspiral and merge within the age of the Universe. Such black-hole mergers have been predicted in two main types of formation models, involving isolated binaries in galactic fields or dynamical interactions in young and old dense stellar environments. The measured masses robustly demonstrate that relatively "heavy" black holes (≳25M⊙) can form in nature. This discovery implies relatively weak massive-star winds and thus the formation of GW150914 in an environment with metallicity lower than ∼1/2 of the solar value. The rate of binary black-hole mergers inferred from the observation of GW150914 is consistent with the higher end of rate predictions (≳1Gpc−3yr−1) from both types of formation models. The low measured redshift (z∼0.1) of GW150914 and the low inferred metallicity of the stellar progenitor imply either binary black-hole formation in a low-mass galaxy in the local Universe and a prompt merger, or formation at high redshift with a time delay between formation and merger of several Gyr. This discovery motivates further studies of binary-black-hole formation astrophysics. It also has implications for future detections and studies by Advanced LIGO and Advanced Virgo, and gravitational-wave detectors in space.

The Cardinality Balanced Multi-Target Multi-Bernoulli Filter and Its Implementations

Abstract: It is shown analytically that the multitarget multiBernoulli (MeMBer) recursion, proposed by Mahler, has a significant bias in the number of targets. To reduce the cardinality bias, a novel multiBernoulli approximation to the multi-target Bayes recursion is derived. Under the same assumptions as the MeMBer recursion, the proposed recursion is unbiased. In addition, a sequential Monte Carlo (SMC) implementation (for generic models) and a Gaussian mixture (GM) implementation (for linear Gaussian models) are proposed. The latter is also extended to accommodate mildly nonlinear models by linearization and the unscented transform.