1,027 research outputs found

    Variance component models for survival data

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    Extensions of the Cox proportional hazards model for survival data are studied where allowance is made for unobserved heterogeneity and for correlation between the life times of several individuals The extended models are frailtymodels inspired by Yashin et al Estimation is carried out using the EM algorithm Inference is discussed and potential applications are outlined in particular to statistical research in human genetics using twin data or adoption data aimed at separating the eects of genetic and environmental factors on mortalit

    Recreational Fishing Initiatives Fund Final Report: Can recreational fishers provide a cost effective means for monitoring artificial reefs?

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    Artificial reefs have been constructed and deployed in over 50 countries around the world to enhance the productivity of aquatic habitats and fishing experiences. In April 2013, two purpose-built concrete artificial reefs were deployed in Geographe Bay, Western Australia to provide additional fish habitat and increase upwelling and thus enhance recreational fishing opportunities. Due to the relatively high cost of planning, purchasing and deploying these structures, it is important to understand spatial and temporal usage of the reef by fish assemblages, in order to determine the extent to which fishing opportunities are actually enhanced. One potential method to reduce monitoring costs is to utilise volunteers from the general public to collect data, i.e. citizen science. The overall objective of this project was to determine whether recreational fishers, through a citizen science program, could potentially provide an effective means for monitoring artificial reefs

    Direct composition profiling in III-V nanostructures by cross-sectional STM

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    Using cross-sectional STM we have studied the local composition in III–V nanostructures such as GaAs/InGaAs quantum wells, InGaNAs/InP quantum wells and quantum dots, and InAs/GaAs self-assembled quantum dots. We are able to determine the local composition by either simply counting the constituent atoms, measuring the local lattice constant or measuring the relaxation of the cleaved surface due to the elastic field of the buried strained nanostructures

    Anticancer RuII and RhIII Piano-Stool Complexes that are Histone Deacetylase Inhibitors

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    The first examples of RuII and RhIII piano-stool complex histone deacetylase (HDAC) inhibitors are presented. The novel complexes have antiproliferative activity against H460 non-small-cell lung carcinoma cells that is comparable to the clinically used HDAC inhibitor suberoylanilide hydroxamic acid (SAHA). Strong evidence for HDAC inhibition as a primary mechanism of action is provided. The complexes reported here represent an important step towards the design of highly active and selective HDAC inhibitors

    Cosmic Rays From Cosmic Strings

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    It has been speculated that cosmic string networks could produce ultra-high energy cosmic rays as a by-product of their evolution. By making use of recent work on the evolution of such networks, it will be shown that the flux of cosmic rays from cosmologically useful, that is GUT scale strings, is too small to be used as a test for strings with any foreseeable technology.Comment: 11, Imperial/TP/93-94/2

    A weakly stable algorithm for general Toeplitz systems

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    We show that a fast algorithm for the QR factorization of a Toeplitz or Hankel matrix A is weakly stable in the sense that R^T.R is close to A^T.A. Thus, when the algorithm is used to solve the semi-normal equations R^T.Rx = A^Tb, we obtain a weakly stable method for the solution of a nonsingular Toeplitz or Hankel linear system Ax = b. The algorithm also applies to the solution of the full-rank Toeplitz or Hankel least squares problem.Comment: 17 pages. An old Technical Report with postscript added. For further details, see http://wwwmaths.anu.edu.au/~brent/pub/pub143.htm

    Gender moderates the relationship between empathy and aggressiveness in sport: The mediating role of anger

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    This research investigated whether gender moderates, and anger mediates, the relationship between empathy (i.e., perspective taking and empathic concern) and aggressiveness in sport. In Study 1, perspective taking and empathic concern were negatively associated with aggressiveness, and this effect was stronger in women compared to men. In Study 2, perspective taking was a negative predictor of aggressiveness and antisocial behavior in sport, and anger mediated these relationships in women, but not in men. Our findings suggest that empathy and emotion-based strategies targeted at reducing aggressiveness in sport need to be tailored for males and females

    Metabolic effects of breaking prolonged sitting with standing or light walking in older South Asians and White Europeans: a randomized acute study

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    Background: Prolonged sitting is common in older adults and associated with insulin resistance and poor cardiometabolic health. We investigate whether breaking prolonged sitting with regular short bouts of standing or light walking improves postprandial metabolism in older white European and South Asian adults and whether effects are modified by ethnic group. Methods: Thirty South Asian (15 women) and 30 white European (14 women) older adults (65-79 years) undertook three experimental conditions in random order. 1) Prolonged sitting: continuous sitting during a 7.5 h observation period consuming two standardised mixed meals. 2) Standing breaks: sitting interrupted with 5 mins of standing every 30 mins (accumulating 60 mins of standing over the observation period). 3) Walking Breaks: sitting interrupted with 5 mins of self-paced light walking every 30 mins (accumulating 60 mins of walking). Blood samples (glucose, insulin, triglycerides) and blood pressure were sampled regularly throughout each condition. Results: Compared with prolonged sitting, walking breaks lowered postprandial insulin by 16.3 mU/l, (95% CI 19.7, 22.0) with greater reductions (p = 0.029) seen in South Asians (22.4 mU/l; 12.4, 32.4) than White Europeans (10.3 mU/l; 5.9, 14.7). Glucose (0.3 mmol/l; 0.1, 0.5) and blood pressure (4 mmHg; 2, 6), but not triglycerides, were lower with walking breaks, with no ethnic differences. Standing breaks did not improve any outcome. Conclusions: Breaking prolonged sitting with short bouts of light walking, but not standing, resulted in clinically meaningful improvements in markers of metabolic health in older adults, with South Asians gaining a greater reduction in postprandial insulin

    TRPV1: A Target for Next Generation Analgesics

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    Transient Receptor Potential Vanilloid 1 (TRPV1) is a Ca2+ permeant non-selective cation channel expressed in a subpopulation of primary afferent neurons. TRPV1 is activated by physical and chemical stimuli. It is critical for the detection of nociceptive and thermal inflammatory pain as revealed by the deletion of the TRPV1 gene. TRPV1 is distributed in the peripheral and central terminals of the sensory neurons and plays a role in initiating action potentials at the nerve terminals and modulating neurotransmitter release at the first sensory synapse, respectively. Distribution of TRPV1 in the nerve terminals innervating blood vessels and in parts of the CNS that are not subjected to temperature range that is required to activate TRPV1 suggests a role beyond a noxious thermal sensor. Presently, TRPV1 is being considered as a target for analgesics through evaluation of different antagonists. Here, we will discuss the distribution and the functions of TRPV1, potential use of its agonists and antagonists as analgesics and highlight the functions that are not related to nociceptive transmission that might lead to adverse effects

    MET-receptor targeted fluorescent imaging and spectroscopy to detect multifocal papillary thyroid cancer

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    Purpose: Multifocal disease in PTC is associated with an increased recurrence rate. Multifocal disease (MD) is underdiagnosed with the current gold standard of pre-operative ultrasound staging. Here, we evaluate the use of EMI-137 targeted molecular fluorescence-guided imaging (MFGI) and spectroscopy as a tool for the intra-operative detection of uni- and multifocal papillary thyroid cancer (PTC) aiming to improve disease staging and treatment selection. Methods: A phase-1 study (NCT03470259) with EMI-137 was conducted to evaluate the possibility of detecting PTC using MFGI and quantitative fiber-optic spectroscopy. Results: Fourteen patients underwent hemi- or total thyroidectomy (TTX) after administration of 0.09 mg/kg (n = 1), 0.13 mg/kg (n = 8), or 0.18 mg/kg (n = 5) EMI-137. Both MFGI and spectroscopy could differentiate PTC from healthy thyroid tissue after administration of EMI-137, which binds selectively to MET in PTC. 0.13 mg/kg was the lowest dosage EMI-137 that allowed for differentiation between PTC and healthy thyroid tissue. The smallest PTC focus detected by MFGI was 1.4 mm. MFGI restaged 80% of patients from unifocal to multifocal PTC compared to ultrasound. Conclusion: EMI-137-guided MFGI and spectroscopy can be used to detect multifocal PTC. This may improve disease staging and treatment selection between hemi- and total thyroidectomy by better differentiation between unifocal and multifocal disease. Trial registration: NCT03470259.</p
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