On the numerical solution of the elastodynamic problem by a boundary integral equation method

A numerical method for the Dirichlet initial boundary value problem for the elastic equation in the exterior and unbounded region of a smooth closed simply connected 2-dimensional domain, is proposed and investigated. This method is based on a combination of a Laguerre transformation with respect to the time variable and a boundary integral equation approach in the spatial variables. Using the Laguerre transformation in time reduces the time-depended problem to a sequence of stationary boundary value problems, which are solved by a boundary layer approach resulting to a sequence of boundary integral equations of the first kind. The numerical discretization and solution are obtained by a trigonometrical quadrature method. Numerical results are included.Comment: 17 pages, 2 figures, 6 table

How do Pay Transparency Laws Impact the Gender Pay Gap in the United States?

After much progress during the late 1900s, the gender pay gap has hardly closed in the last two decades. As policy makers look for new solutions, many governing bodies have turned to pay transparency laws, which make employee salaries transparent to employees. There have been several international studies on this topic, and almost all found that these laws are very effective in decreasing the pay gap. This research is extremely important, as it suggests that these policies push us further towards equality, and makes gender based discrimination less common in the workplace. In my study, I conduct a difference in differences study and a fixed effects regression analysis using data from the Consumer Population Survey. I find positive effects of pay transparency laws on women’s relative wages. I find a 7% difference in the gender wage gap, controlling for observable characteristics in Colorado (which has pay transparency) and Washington (which does not have pay transparency), after Colorado passed their law in 2021. Using an interaction term, the fixed effects regression model suggests that being a woman in a state with a pay transparency law increases wages around 8.57%. Both these results demonstrate that the pay transparency laws are an important tool to be used to close the gender wage gap

Using Top-down and Bottom-up Costing Approaches in LMICs: The Case for Using Both to Assess the Incremental Costs of New Technologies at Scale.

PURPOSE: Estimating the incremental costs of scaling-up novel technologies in low-income and middle-income countries is a methodologically challenging and substantial empirical undertaking, in the absence of routine cost data collection. We demonstrate a best practice pragmatic approach to estimate the incremental costs of new technologies in low-income and middle-income countries, using the example of costing the scale-up of Xpert Mycobacterium tuberculosis (MTB)/resistance to riframpicin (RIF) in South Africa. MATERIALS AND METHODS: We estimate costs, by applying two distinct approaches of bottom-up and top-down costing, together with an assessment of processes and capacity. RESULTS: The unit costs measured using the different methods of bottom-up and top-down costing, respectively, are $US16.9 and$US33.5 for Xpert MTB/RIF, and $US6.3 and$US8.5 for microscopy. The incremental cost of Xpert MTB/RIF is estimated to be between $US14.7 and$US17.7. While the average cost of Xpert MTB/RIF was higher than previous studies using standard methods, the incremental cost of Xpert MTB/RIF was found to be lower. CONCLUSION: Costs estimates are highly dependent on the method used, so an approach, which clearly identifies resource-use data collected from a bottom-up or top-down perspective, together with capacity measurement, is recommended as a pragmatic approach to capture true incremental cost where routine cost data are scarce

The effectiveness and cost-effectiveness of respite for caregivers of frail older people

The proportion of frail elderly people in the industrialized world is increasing. Respite care is a potentially important way of maintaining the quality of life for these people and their caregivers. The objective of this systematic review was to determine the effectiveness and cost-effectiveness of different models of community-based respite care for frail older people and their caregivers. To identify relevant studies, 37 databases were searched, and reference checking and citation searches were undertaken. Well-controlled effectiveness studies were eligible for inclusion, with uncontrolled studies admissible only in the absence of higher-quality evidence. Studies assessed the effect of community-based respite on caregivers of frail elderly people relative to usual care or to another support intervention. Eligible economic evaluations also addressed costs. Where appropriate, data were synthesized using standard meta-analytic techniques. Ten randomized, controlled trials, seven quasi-experimental studies and five uncontrolled studies were included in the review. For all types of respite, the effects upon caregivers were generally small, with better-controlled studies finding modest benefits only for certain subgroups, although many studies reported high levels of caregiver satisfaction. No reliable evidence was found that respite care delays entry to residential care or adversely affects frail older people. The economic evaluations all assessed day care, which tended to be associated with similar or higher costs than usual care. Given the increasing numbers of frail elderly people and the lack of up-to-date, good-quality evidence for all types of respite care, better-quality evidence is urgently needed to inform current policy and practice

Evaluation of a Command-line Parser-based Order Entry Pathway for the Department of Veterans Affairs Electronic Patient Record

Objective: To improve and simplify electronic order entry in an existing electronic patient record, the authors developed an alternative system for entering orders, which is based on a command- interface using robust and simple natural-language techniques. Design: The authors conducted a randomized evaluation of the new entry pathway, measuring time to complete a standard set of orders, and users' satisfaction measured by questionnaire. A group of 16 physician volunteers from the staff of the Department of Veterans Affairs Puget Sound Health Care System-Seattle Division participated in the evaluation. Results: Thirteen of the 16 physicians (81%) were able to enter medical orders more quickly using the natural-language-based entry system than the standard graphical user interface that uses menus and dialogs (mean time spared, 16.06 ± 4.52 minutes; P=0.029). Compared with the graphical user interface, the command--based pathway was perceived as easier to learn (P<0.01), was considered easier to use and faster (P<0.01), and was rated better overall (P<0.05). Conclusion: Physicians found the command- interface easier to learn and faster to use than the usual menu-driven system. The major advantage of the system is that it combines an intuitive graphical user interface with the power and speed of a natural-language analyze

Effects of Serving Temperature on Sensory Perception and Acceptance of Brewed Coffee

Coffee continues to be one of the most widely consumed beverages worldwide. How an individual perceives a cup of coffee is impacted by a plethora of factors including origin, growing climate, roasting level, and consumption habits. This thesis utilized both trained descriptive panelists and untrained consumer panelists to analyze how serving/consumption temperature modulates sensory perception of brewed coffee in regards to appearance, aroma, flavor, taste, and mouthfeel. Three varieties of coffee (Colombia, Ethiopia, and Kenya) were brewed and served to panelists at four temperatures: 70, 55, 40, and 25 °C. In one study (Study 1, Chapter 3), results from descriptive analysis showed that product temperature had a larger effect in modulating sensory perception than did coffee variety. In another descriptive analysis study (Study 2, Chapter 3), trained panelists found that serving temperature had a more significant effect on perception than freshness, up to 90 minutes, of the brewed coffee sample of Ethiopian variety. Utilizing an untrained consumer panel and a Check-All-That-Apply (CATA) method to assess these same coffee samples, results showed that both serving temperature and coffee variety largely contributed to the variation in sensory perception. While these consumer panelists were more effective in differentiating between coffee varieties when assessing the samples at a lower (40 °C) temperature, liking of the sample was highest when served at hot temperatures (55 and 70 °C). This indicates that subtle attributes of brewed coffee may be easier to identify when served at lower temperatures. In a final study using CATA, additions of cream and sugar were added to the brewed coffee sample and served at four temperatures. Results showed that temperature is a significant modulator of sensory perception in enhanced coffee (i.e., brewed coffee with cream and/or sugar). The findings of this thesis show the importance of controlling temperature for the sensory evaluation of coffee products, since significant variations in both qualitative and quantitative sensory perception arise from changes in product temperature

An iterative method based on boundary integrals for elliptic Cauchy problems in semi-infinite domains

In this study, we investigate the problem of reconstruction of a stationary temperature field from given temperature and heat flux on a part of the boundary of a semi-infinite region containing an inclusion. This situation can be modelled as a Cauchy problem for the Laplace operator and it is an ill-posed problem in the sense of Hadamard. We propose and investigate a Landweber-Fridman type iterative method, which preserve the (stationary) heat operator, for the stable reconstruction of the temperature field on the boundary of the inclusion. In each iteration step, mixed boundary value problems for the Laplace operator are solved in the semi-infinite region. Well-posedness of these problems is investigated and convergence of the procedures is discussed. For the numerical implementation of these mixed problems an efficient boundary integral method is proposed which is based on the indirect variant of the boundary integral approach. Using this approach the mixed problems are reduced to integral equations over the (bounded) boundary of the inclusion. Numerical examples are included showing that stable and accurate reconstructions of the temperature field on the boundary of the inclusion can be obtained also in the case of noisy data. These results are compared with those obtained with the alternating iterative method

An alternating potential based approach for a Cauchy problem for the Laplace equation in a planar domain with a cut

We consider a Cauchy problem for the Laplace equation in a bounded region containing a cut, where the region is formed by removing a sufficiently smooth arc (the cut) from a bounded simply connected domain D. The aim is to reconstruct the solution on the cut from the values of the solution and its normal derivative on the boundary of the domain D. We propose an alternating iterative method which involves solving direct mixed problems for the Laplace operator in the same region. These mixed problems have either a Dirichlet or a Neumann boundary condition imposed on the cut and are solved by a potential approach. Each of these mixed problems is reduced to a system of integral equations of the first kind with logarithmic and hypersingular kernels and at most a square root singularity in the densities at the endpoints of the cut. The full discretization of the direct problems is realized by a trigonometric quadrature method which has super-algebraic convergence. The numerical examples presented illustrate the feasibility of the proposed method

On the Non-Linear Integral Equation Approach for an Inverse Boundary Value Problem for the Heat Equation

We consider the inverse problem of reconstructing the interior boundary curve of a doubly connected domain from the knowledge of the temperature and the thermal flux on the exterior boundary curve. The use of the Laguerre transform in time leads to a sequence of stationary inverse problems. Then, the application of the modified single-layer ansatz, reduces the problem to a sequence of systems of non-linear boundary integral equations. An iterative algorithm is developed for the numerical solution of the obtained integral equations. We find the Fr\'echet derivative of the corresponding integral operator and we show the unique solvability of the linearized equation. Full discretization is realized by a trigonometric quadrature method. Due to the inherited ill-possedness of the derived system of linear equations we apply the Tikhonov regularization. The numerical results show that the proposed method produces accurate and stable reconstructions.Comment: 16 pages, 3 figure

Amplifying Voices: Co-researchers with Learning Disabilities Use a Co-designed Survey to “have a conversation with the public”

The concept of ‘giving voice’ in research and in the design of accessible technologies involving people with learning disabilities (LDs) has been often used to highlight the necessity for careful consideration of their opinions and needs. Those who ‘communicate differently’ are often portrayed as the beneficiaries of the technological advancements rather than contributors to the technology that can benefit everybody. Here, we present a case study whereby people with LDs co-designed an inclusive survey platform and created an online survey to “have a conversation with the public” and to challenge attitudes towards LDs. Over 800 participants with and without disabilities or impairments completed the survey and reflected on their learning experience. Using qualitative and quantitative methods, we found that the co-created platform enabled all – the co-researchers and the respondents – to have their ‘voices amplified’ and to be listened to in a meaningful way – just as in ‘a conversation’ between people