Auxiliary Likelihood-Based Approximate Bayesian Computation in State Space Models

A computationally simple approach to inference in state space models is proposed, using approximate Bayesian computation (ABC). ABC avoids evaluation of an intractable likelihood by matching summary statistics for the observed data with statistics computed from data simulated from the true process, based on parameter draws from the prior. Draws that produce a 'match' between observed and simulated summaries are retained, and used to estimate the inaccessible posterior. With no reduction to a low-dimensional set of sufficient statistics being possible in the state space setting, we define the summaries as the maximum of an auxiliary likelihood function, and thereby exploit the asymptotic sufficiency of this estimator for the auxiliary parameter vector. We derive conditions under which this approach - including a computationally efficient version based on the auxiliary score - achieves Bayesian consistency. To reduce the well-documented inaccuracy of ABC in multi-parameter settings, we propose the separate treatment of each parameter dimension using an integrated likelihood technique. Three stochastic volatility models for which exact Bayesian inference is either computationally challenging, or infeasible, are used for illustration. We demonstrate that our approach compares favorably against an extensive set of approximate and exact comparators. An empirical illustration completes the paper.Comment: This paper is forthcoming at the Journal of Computational and Graphical Statistics. It also supersedes the earlier arXiv paper "Approximate Bayesian Computation in State Space Models" (arXiv:1409.8363

Barriers to care for depressed older people : perceptions of aged care among medical professionals

The current study evaluated barriers to detection of depression among older people. Focus groups were conducted with 21 professional carers, 4 nurses, 10 general practitioners, and 7 aged care managers. The results demonstrated that care for older people is primarily focused on physical care. Further, staff resources, a lack of continuity of care, multiple co-morbidities, reluctance by older people to discuss depression, negative attitudes among carers, as well as a lack of skills all contributed to a failure to detect and treat depression. The implications of these findings for training programs for professional carers are discussed.<br /

Shear Strength of Continuous Lightly Reinforced Concrete Joist Systems

The objective of this research is to study the shear strength of continuous lightly reinforced concrete joist systems. Six two span joists, with and without web reinforcement, and two multiple web joists without web reinforcement were tested. The main focus of this study was to determine the shear cracking capacity and to investigate load sharing between joists. Shear cracking loads are determined using crack pattern and stirrup strain analyses. Behavior is evaluated in both the .o,.irive and the negative moment regions. The primary variables in this research are the longitudinal reinforcement ratio, p,.. (0.76% and 1.04% for negative moment regions and from 0.79% to 2.43% for positive moment regions), and nominal stirrup strength, Pvfvy (0 to 70 psi) for single web joists and placement of the load in multiple web joists. Stirrup effectiveness in joists is analyzed based upon ACI provisions and the number of stirrups intercepted by the critical shear crack. Nominal shear stresses and load sharing between the joists are compared with current ACI design pro , The tests indicate that ACI 318-89 overestimates the shear cracking load and shear capacity of lightly reinforced concrete joists in negative moment regions, and under estimates the shear cracking load but not the shear capacity in positive moment regiOns. In the study, the stirrup contribution in both the negative and positive moment regions equaled or exceeded the value predicted by ACI 318-89. In the positive moment regions of members with stirrups, the concrete contribution to shear capacity was often below the shear cracking load, contrary to the usual assumption. The study indicates that significant load sharing occurs between the joists, but that the load sharing is adequate only to distribute local overloads. The additional I 0% in the concrete contribution to shear capacity, as allowed by ACI 318-89, is not available for joist systems as a whole

Shear Strength of Continuous Lightly Reinforced T-Beams

The shear strength of continuous lightly reinforced concrete T -beams is studied. Six twospan T -beams with and without web reinforcement are tested. The primary variables are longitudinal reinforcement ratio (0.75% and 1.0%) and nominal stirrup strength (0 to 82 psi). The test results are analyzed and compared with the shear design provisions of "Building Code Requirements for Reinforced Concrete (ACI 318-89)" and predictions of other investigators, including predictions obtained using the modified compression field theory. The tests indicate that ACI 318-89 overpredicts the concrete shear capacity of lightly reinforced beams without shear reinforcement. Little difference exists between shear cracking stresses in the negative and positive moment regions for beams in the current study. For both the negative and positive moment regions, the stirrup contribution to shear strength exceeds the value predicted by ACI 318-89. Stirrup contribution to shear strength increases with increasing flexural reinforcement ratio. Overall, the ACI 318-89 shear provisions are conservative for the beams tested in the current study. Two procedures based on the modified compression field theory are also conservative. ACI 318-89 better predicts the nominal shear strength of the beams in the current study than either of the modified compression field theory procedures

Development Length Criteria: Bars Without Transverse Reinforcement

An expression that accurately represents development and splice strength as a function of concrete cover and bar spacing is developed and used to establish and evaluate modifications to the bond and development provisions of the ACI Building Code (ACI 318-89) for bars without transverse reinforcement The expression for development and splice strength is similar in form to expressions developed by Orangun, Jirsa, and Breen (1975, 1977), but is obtained using techniques that limit the effects of unintentional bias in the test data. The resulting expression provides a more accurate representation of development and splice strength than do the earlier expressions, and provides better guidance when there is a significant difference between the concrete cover and one-half of the clear spacing between bars. The expression for development and splice strength is used to establish new criteria that follow the format of ACI 318-89 and to evaluate design criteria that are currently under review by ACI Subcommittee 318-B. The new criteria that follow the format of ACI 318-89 are generally conservative and economical. The provisions under study by Subcommittee 318-B are unconservative for No. 6 bars and smaller with minimum covers and close spacings, and are overconservative for most bars with higher covers and wider spacings. Modifications are recommended that increase both the safety and the economy provided by the provisions under study by ACI Subcommittee 318-B

Knowledge of late-life depression : an empirical investigation of aged care staff

Objectives: This study examined knowledge of late-life depression among staff working in residential and community aged care settings, as well as their previous training in caring for older people with depression. Method: A sample of 320 aged care staff (mean age = 42 years) completed a survey questionnaire. Participants included direct care staff, registered nurses and Care Managers from nursing and residential homes and community aged care services. Results: Less than half of the participating aged care staff had received any training in depression, with particularly low rates in residential care. Although aware of the importance of engaging with depressed care recipients and demonstrating moderate knowledge of the symptoms of depression, a substantial proportion of staff members saw depression as a natural consequence of bereavement, aging or relocation to aged care. Conclusion: Experience in aged care appears to be insufficient for staff to develop high levels of knowledge of depression. Specific training in depression is recommended for staff working in aged care settings in order to improve the detection and management of late-life depression, particularly among direct carers, who demonstrated least knowledge of this common disorder. <br /

Staff-focused interventions to increase referrals for depression in aged care facilities: a cluster randomized controlled trial

Objective:&nbsp;While there is evidence that depression training can improve the knowledge of staff in residential care facilities, there is an absence of research determining whether such training translates into practice change. This study aimed to evaluate the impact of staff training and the introduction of a protocol for routine screening and referral for depression on the numbers of residents detected and referred by care staff for further assessment.Method: A cluster randomized controlled design was used to compare the referral rates for residents in seven facilities randomly allocated into one of three conditions: staff training, staff training plus a screening and referral protocol and wait-list control. Participants were 216 aged care residents (M age&thinsp;=&thinsp;87 years), who agreed to a 12-month audit of their facility file.Results: Staff training on its own did not increase the rate of referrals for depression; however, staff training plus the screening protocol and referral guidelines did lead to a significant increase in the number of residents who were referred to a medical practitioner for further assessment. However, this increase in care staff referrals did not result in substantial changes in the treatment prescribed for residents.Conclusion: Staff training in depression, supplemented with a protocol for routine screening and guidelines on referring residents, can improve pathways to care. However, strategies to overcome barriers to appropriate subsequent treatment of depression are required for staff-focused initiatives to translate into better outcomes for depressed older adults. Methodological limitations of this study are discussed.</div

Predicting Strength of Matched Sets of Test Specimens

Five different methods for a priori estimating bending strength of wood and wood composite specimens are compared in this paper. They are: (1) edge-matching, (2) matching specimens by normal distribution, (3) matching specimens by log-normal distribution, (4) simple linear regression, and (5) multiple linear regression. It was found that the square root of mean square error (RMSE) of percent difference (PD) of predicted modulus of rupture (MOR) is the key measure in comparing the five methods. Multiple linear regression was found to be the best method to predict MOR of a specimen in an edge-matched set. Finally, how to create the prediction limits for mean MOR of a subgroup of specimens is discussed. The prediction limits for predicting MOR make it possible to quantitatively determine the effect of various treatments of wood materials

Nrf2 regulates mass accrual and the antioxidant endogenous response in bone differently depending on the sex and age

Accumulation of reactive oxygen species (ROS) is an important pathogenic mechanism underling the loss of bone mass and strength with aging and other conditions leading to osteoporosis. The transcription factor erythroid 2-related factor2 (Nrf2) plays a central role in activating the cellular response to ROS. Here, we examined the endogenous response of bone regulated by Nrf2, and its relationship with bone mass and architecture in the male and female murine skeleton. Young (3 month-old) and old (15 month-old) Nrf2 knockout (KO) mice of either sex exhibited the expected reduction in Nrf2 mRNA expression compared to wild type (WT) littermates. Nrf2 deletion did not lead to compensatory increase in Nrf1 or Nrf3, other members of this transcription factor family; and instead, Nrf1 expression was lower in KO mice. Compared to the respective WT littermate controls, female KO mice, young and old, exhibited lower expression of both detoxifying and antioxidant enzymes; young male KO mice, displayed lower expression of detoxifying enzymes but not antioxidant enzymes; and old male KO mice showed no differences in either detoxifying or antioxidant enzymes. Moreover, old male WT mice exhibited lower Nrf2 levels, and consequently lower expression of both detoxifying and antioxidant enzymes, compared to old female WT mice. These endogenous antioxidant responses lead to delayed rate of bone acquisition in female KO mice and higher bone acquisition in male KO mice as quantified by DXA and μCT, demonstrating that Nrf2 is required for full bone accrual in the female skeleton but unnecessary and even detrimental in the male skeleton. Therefore, Nrf2 regulates the antioxidant endogenous response and bone accrual differently depending on sex and age. These findings suggest that therapeutic interventions that target Nrf2 could be developed to enhance the endogenous antioxidant response in a sex- and age-selective manner

Knowledge and skills of professional carers working with older people with depression

Objectives: The current study was designed to evaluate the knowledge, skills and self-efficacy of care providers from the perspective of professionals working in the aged-care industry. Method: Participants were 21 professional carers, 10 General Practitioners and 7 aged-care managers. Focus groups, which involved the completion of a semi-structured interview related to knowledge, recognition, confidence, referral procedures and use of screening tools for the detection of depression, were conducted. Results: The results showed that all groups of respondents recognised significant gap in the knowledge and awareness of depression among professional care staff working with older people in both the community and residential care-settings. Skills in the detection and monitoring of depression and the self-efficacy of these care staff were also seen to be a problem. Discussion: The implications of these findings in terms of training programmes for professional carers working in the aged health care sector are discussed.<br /