Using Proxies for the Short Rate: When are Three Months Like an Instant?

The dynamics of the unobservable "short" or "instantaneous" rate of interest are frequently estimated using a proxy variable. We show the biases resulting from this practice (the "proxy" problem) are related to the derivatives of the proxy with respect to the short rate and the (inverse) function from the proxy to the short rate. Analytic results show that the proxy problem is not economically significant for single- factor affine models, for parameter values consistent with US data. In addition, for the two-factor affine model of Longstaff and Schwartz (1992), the proxy problem is only economically significant for pricing discount bonds with maturities of more than 5 years. We also describe two different procedures which can be used to assess the magnitude of the proxy problem in more general interest rate models. Numerical evaluation of a nonlinear single-factor model suggests that the proxy problem can significantly affect both estimates of the diffusion function and discount bond prices.interest rates, proxies, term structure

An evidence-based guide to the efficacy and safety of isometric resistance training in hypertension and clinical implications.

More than 30 randomized controlled trials, supported by individual patient-level and group-level meta-analyses and a Delphi analysis of expert opinion, unequivocally show isometric resistance training (IRT) elicits antihypertensive benefits in healthy people and those with chronic illness. We aim to provide efficacy and safety evidence, and a guide for IRT prescription and delivery. Recommendations are made for the use of IRT in specific patient populations and appropriate methods for IRT delivery. Published data suggest IRT consistently elicits mean blood pressure reductions of 7.4/3.3 mmHg systolic blood pressure/diastolic blood pressure, equivalent to antihypertensive medication monotherapy. Blood pressure reductions of this size are associated with an approximate 13% to 22% reduction in major cardiovascular events. Moreover, IRT is safe in a range of patient populations. We suggest that IRT has the greatest potential benefit when used as an antihypertensive therapy in individuals unwilling and/or unable to complete aerobic exercise, or who have had limited adherence or success with it; individuals with resistant or uncontrolled hypertension, already taking at least two pharmacological antihypertensive agents; and healthy or clinical populations, as an adjunct to aerobic exercise and dietary intervention in those who have not yet attained control of their hypertension. IRT is efficacious and produces clinically meaningful blood pressure reductions (systolic blood pressure, 7 mmHg; diastolic blood pressure, 3 mmHg). IRT is safe and typical program delivery requires only about 17 min weekly. IRT should be used as an adjunct to other exercise modalities, in people unable to complete other types of exercise, or in resistant hypertension. [Abstract copyright: © 2023. The Author(s).

Determining position and orientation of a 3-wheel robot on a pipe using an accelerometer

Accurate positioning of robots on pipes is a challenge in automated industrial inspection. It is typically achieved using expensive and cumbersome external measurement equipment. This paper presents an Inverse Model method for determining the orientation angle (α ) and circumferential position angle (ω) of a 3 point of contact robot on a pipe where measurements are taken from a 3-axis accelerometer sensor. The advantage of this system is that it provides absolute positional measurements using only a robot mounted sensor. Two methods are presented which follow an analytical approximation to correct the estimated values. First, a correction factor found though a parametric study between the robot geometry and a given pipe radius, followed by an optimization solution which calculates the desired angles based on the system configuration, robot geometry and the output of a 3-axis accelerometer. The method is experimentally validated using photogrammetry measurements from a Vicon T160 positioning system to record the position of a three point of contact test rig in relation to a test pipe in a global reference frame. An accelerometer is attached to the 3 point of contact test rig which is placed at different orientation (α ) and circumferential position (ω) angles. This work uses a new method of processing data from an accelerometer sensor to obtain the α and ω angles. The experimental results show a maximum error of 3.40° in α and 4.17° in ω , where the ω circumferential positional error corresponds to ±18mm for the test pipe radius of 253mm

Exercise therapy and cardiac, autonomic and systemic function in patients with chronic heart failure

Background Exercise training is now accepted as a safe, adjunct therapy in stable heart failure patients. Acceptance of exercise training or therapy within this population is due to the benefits that have been demonstrated over the past three decades in trials and data syntheses presented in systematic reviews and meta-analyses. As new concepts emerge and with an increase in the number of trials comes the challenge of keeping up-to date with all the information, deciphering what's relevant, deciding how to interpret and apply the findings and what should happen next. Fortunately, the research methodologies of systematic review and meta-analysis provide a suitable platform for collecting, analysing and critically appraising studies. Methods An initial evidence mapping exercise identified the current level of research activity in regard to the synthesis of evidence focusing on the broad question of the benefits and/or effects of exercise training in heart failure patients. The objective of the exercise was to identify gaps in research synthesis and areas in which research synthesis would be valuable. A series of research syntheses were then conducted based on the identified gaps, using systematic reviews as the research methodology, and applying the statistical technique of meta-analysis where possible. Results While some of the effects of exercise training are now well established, e.g., improved functional capacity and quality of life, new trials and new concepts continue to emerge. Evidencing mapping highlighted a number of areas in which research synthesis was limited or out dated. The identified areas addressed the effect of exercise training on specific areas of cardiac, autonomic and systemic inflammatory markers in chronic heart failure patients; all associated with the pathogenesis and progression of heart failure. Evidence from systematic reviews and meta-analyses demonstrated that exercise training/therapy resulted in statistically significant improvements in: 1) endothelial function (FMD and EPCs), 2) direct (MSNA) and indirect (HRR, HRV) measures of autonomic function, 3) cardiac biomarkers (BNP, NT-proBNP) and 4) diastolic function, measured as E/E’. However, the evidence for improvements in a number of inflammatory markers was inconclusive, and limited evidence is currently available to allow for any conclusion to be drawn on the effect of exercise on emerging heart failure biomarkers. Conclusion This thesis utilised systematic reviews and meta-analyses as the research methodology to answer questions in relation to exercise training in heart failure patients. This work adds to the current evidence base by providing a robust synthesis of data in regard to effects of exercise training and therapy on endothelial function, autonomic function, inflammatory markers, biomarkers and diastolic function in heart failure patients