Discontinuity Approach Research Articles

The impact of the U.S federal minimum legal drinking age law on alcohol involved firearm suicide: a regression discontinuity approach.

Suicide is a leading cause of death for young people. Half of young adult suicides are by firearm, and many involve alcohol consumption. We aimed to assess the impact of the minimum legal drinking age (MLDA) of 21 years on rates of alcohol positive firearm and non-firearm suicide. We used a regression discontinuity approach with data from the National Violent Death Reporting System (NVDRS) 2005-2021, among U.S suicide decedents in 14 states aged 16-35 years. The primary outcomes were the change in the proportion of tests positive for alcohol and the change in rates of alcohol positive suicide per 100,000 population at the MLDA. Across 14 states and 169 state-years, there were 434 alcohol positive suicides at age 20 and 684 alcohol positive suicides at age 21. The percentage of suicides with a positive alcohol test increased from 29.5% at age 20 to 38.7% at age 21 (p<0.001), with a larger increase among firearm suicides relative to non-firearm suicides. Accounting for age-related trends, the total alcohol positive suicide rate increased by 1.52 per 100,000 (p<0.001) at the MLDA, mostly due to an increase in alcohol positive firearm suicide. Compared to the expected rate in the absence of the MLDA, there was a 47.5% (95% CI 24.1%-81.8%) excess in firearm suicides, equivalent to 137 (95% CI 82-191) excess deaths. There was no discontinuity in the rate of alcohol negative firearm suicides at age 21. Blood alcohol content was not affected by the MLDA but was higher for firearm suicides across all ages. There was a large increase in the rate of alcohol positive suicide at the minimum legal drinking age (MLDA), driven by firearm suicide. Policies and programmes should aim to weaken the link between alcohol and firearms among those at or just above legal drinking age to prevent suicide. The Commonwealth Fund and The Joyce Foundation.

The impact of spousal retirement on health—an empirical analysis based on CFPS

IntroductionHealth impacts associated with spousal retirement vary significantly across countries and datasets, underscoring the need to examine this relationship within the Chinese context. This study aims to explore how spousal retirement affects individual health in China.MethodsUtilizing data from the China Family Panel Studies (CFPS) for the years 2014, 2016, 2018, and 2020, this research applies a fuzzy regression discontinuity approach to assess the effects of spousal retirement on health outcomes.ResultsFindings indicate that a wife’s retirement positively impacts her husband’s mental health but negatively affects his physical health. Conversely, a husband’s retirement improves his wife’s self-rated health. Further analysis reveals that a husband’s retirement significantly enhances his wife’s marital satisfaction, contributing to longer sleep durations and, subsequently, better self-rated health.DiscussionThis study highlights the nuanced effects of spousal retirement on individual health, with implications for understanding the marital and health dynamics within aging populations in China.

Adaptive Integral Sliding Mode Control with Chattering Elimination Considering the Actuator Faults and External Disturbances for Trajectory Tracking of 4Y Octocopter Aircraft

This paper presents a control strategy for a 4Y octocopter aircraft that is influenced by multiple actuator faults and external disturbances. The approach relies on a disturbance observer, adaptive type-2 fuzzy sliding mode control scheme, and type-1 fuzzy inference system. The proposed control approach is distinct from other tactics for controlling unmanned aerial vehicles because it can simultaneously compensate for actuator faults and external disturbances. The suggested control technique incorporates adaptive control parameters in both continuous and discontinuous control components. This enables the production of appropriate control signals to manage actuator faults and parametric uncertainties without relying only on the robust discontinuous control approach of sliding mode control. Additionally, a type-1 fuzzy logic system is used to build a fuzzy hitting control law to eliminate the occurrence of chattering phenomena on the integral sliding mode control. In addition, in order to keep the discontinuous control gain in sliding mode control at a small value, a nonlinear disturbance observer is constructed and integrated to mitigate the influence of external disturbances. Moreover, stability analysis of the proposed control method using Lyapunov theory showcases its potential to uphold system tracking performance and minimize tracking errors under specified conditions. The simulation results demonstrate that the proposed control strategy can significantly reduce the chattering effect and provide accurate trajectory tracking in the presence of actuator faults. Furthermore, the efficacy of the recommended control strategy is shown by comparative simulation results of 4Y octocopter under different failing and uncertain settings.

A New Era of Midnight Mergers: Antitrust Risk and Investor Disclosures

Antitrust authorities search public documents to discover anticompetitive mergers. Thus, investor disclosures may alert them to deals that would otherwise go undetected, creating disincentives for managers to divulge certain transactions. We study this behavior in publicly traded US companies. First, we employ a regression discontinuity approach to estimate the effect of mandatory disclosures. We find that releasing information to investors poses antitrust risk. Second, we introduce a method for measuring undisclosed mergers that relies on financial accounting reporting requirements. We find that undisclosed mergers total $1.85 trillion between 2002 and 2016. (JEL D22, G32, G34, G38, K21, L41, M41)

The intergenerational effects of requiring unemployment benefit recipients to engage in non-search activities

We use a quasi-experimental design and national administrative data to analyze the intergenerational effects of introducing non-search activity requirements for long-term unemployment benefit recipients aged 18–34. The young-adult children of these recipients were in early adolescence when the requirements were introduced. Using a regression discontinuity approach, we find that young adults, particularly men, whose fathers were subject to the requirements have a lower incidence of unemployment benefit receipt compared to those whose fathers were not. More detailed investigation suggests completion of the mandated activities, role modeling, changes in attitudes, improved health, and greater support and stability as potential channels.

Computational Study of Shocked V-Shaped N2/SF6 Interface across Varying Mach Numbers

The Mach number effect on the Richtmyer–Meshkov instability (RMI) evolution of the shocked V-shaped N2/SF6 interface is numerically studied in this research. Four distinct Mach numbers are taken into consideration for this purpose: Ms=1.12,1.22,1.42, and 1.62. A two-dimensional space of compressible two-component Euler equations is simulated using a high-order modal discontinuous Galerkin approach to computational simulations. The numerical results show good consistency when compared to the available experimental data. The computational results show that the RMI evolution in the shocked V-shaped N2/SF6 interface is critically dependent on the Mach number. The flow field, interface deformation, intricate wave patterns, inward jet development, and vorticity generation are all strongly impacted by the shock Mach number. As the Mach number increases, the V-shaped interface deforms differently, and the distance between the Mach stem and the triple points varies depending on the Mach number. Compared to lower Mach numbers, higher ones produce larger rolled-up vortex chains. A thorough analysis of the Mach number effect identifies the factors that propel the creation of vorticity during the interaction phase. Moreover, kinetic energy and enstrophy both dramatically rise with increasing Mach number. Lastly, a detailed analysis is carried out to determine how the Mach number affects the temporal variations in the V-shaped interface’s features.

Numerical Study of Shock Wave Interaction with V-Shaped Heavy/Light Interface

This paper investigates numerically the shock wave interaction with a V-shaped heavy/light interface. For numerical simulations, we choose six distinct vertex angles (θ=40∘,60∘,90∘,120∘,150∘, and 170∘), five distinct shock wave strengths (Ms=1.12,1.22,1.30,1.60, and 2.0), and three different Atwood numbers (At=−0.32,−0.77, and −0.87). A two-dimensional space of compressible two-component Euler equations are solved using a third-order modal discontinuous Galerkin approach for the simulations. The present findings demonstrate that the vertex angle has a crucial influence on the shock wave interaction with the V-shaped heavy/light interface. The vertex angle significantly affects the flow field, interface deformation, wave patterns, spike generation, and vorticity production. As the vertex angle decreases, the vorticity production becomes more dominant. A thorough analysis of the vertex angle effect identifies the factors that propel the creation of vorticity during the interaction phase. Notably, smaller vertex angles lead to stronger vorticity generation due to a steeper density gradient, while larger angles result in weaker, more dispersed vorticity and a less complex interaction. Moreover, kinetic energy and enstrophy both dramatically rise with decreasing vortex angles. A detailed analysis is also carried out to analyze the vertex angle effects on the temporal variations of interface features. Finally, the impacts of different Mach and Atwood numbers on the V-shaped interface are briefly presented.

Time-domain simulation of sound propagation through anisotropic porous media for room acoustic applications

Wave-based room acoustic simulations require accurate modeling of sound propagation in the presence of extended (bulk) reacting porous absorbers. The sound absorption in porous media is typically addressed by means of equivalent fluid models that provide frequency-dependent effective material parameters, such as density and bulk modulus. In the time domain, these frequency dependent properties result in the computation of convolution integrals, which is effectively handled via an auxiliary differential equations (ADE) method. In this work, we apply the time-explicit discontinuous Galerkin approach to modelling of sound propagation in anisotropic porous media (with an anisotropic equivalent fluid model) together with the ADE method. We demonstrate the importance of using the extended approach for porous media, where the sound absorption depends not only on the frequency and incident angle, but also on the travelling wave direction.

Error estimates for discontinuous Galerkin time-stepping schemes for the parabolic p-Laplacian: A quasi-norm approach

Error estimates for arbitrary order fully-discrete schemes for the parabolic $p$-Laplacian are considered. The schemes combine the discontinuous Galerkin time-stepping approach for the temporal discretization with classical conforming finite elements in space. In particular, a symmetric -C\'ea Lemma type- error estimate is established for a suitable quasi-norm, under minimal regularity assumptions on the data. The above estimate leads to error bounds of arbitrary order in space and time provided that the necessary regularity is present, without imposing any restrictions between the temporal and spatial discretization parameters. The symmetric structure of the estimate also leads to various error estimates at partition points as well as for the natural energy $L^p(I;W^{1,p}(\Omega))$ norm. Furthermore, an unconditional $L^{\infty}(I;L^2(\Omega))$ stability and error estimate is proved under minimal regularity assumptions, as well as an optimal $L^{\infty}(I;L^2(\Omega))$ error estimate under a suitable restriction between the temporal and spatial discretization parameters and additional regularity of the solution.

Investigating the Potential Short-term Adverse Effects of the Quadrivalent Human Papillomavirus Vaccine: A Novel Regression Discontinuity Analysis.

Human papillomavirus (HPV) vaccination has been offered in over a hundred countries worldwide (including the United Kingdom, since September 2008). Controversy around adverse effects persists, with inconsistent evidence from follow-up of randomized controlled trials and confounding by indication limiting the conclusions drawn from larger-scale observational studies. This study aims to estimate the association between receiving a quadrivalent HPV vaccine and the reporting of short-term adverse effects and to demonstrate the utility of regression discontinuity design for examining side effects in routine data. We applied a novel regression discontinuity approach to a retrospective population-based cohort using primary care data from the UK Clinical Practice Research Datalink linked to hospital and social deprivation data. We examined the new onset of gastrointestinal, neuromuscular, pain, and headache/migraine symptoms using READ and International Classification of Diseases, tenth revision diagnostic codes. For each year between 2012 and 2017, we compared girls in school year 8 (born July/August) who were eligible to receive the vaccine with girls in year 7 (born September/October) who were not eligible. Of the 21,853 adolescent girls in the cohort, 10,881 (50%) were eligible for HPV vaccination. There was no evidence of increased new gastrointestinal symptoms (adjusted odds ratio [OR]: 0.99; 95% confidence interval [CI]: 0.85, 1.15), headache/migraine symptoms (OR: 0.84; 95% CI: 0.70, 1.01), or pain symptoms (OR: 1.05; 95% CI: 0.95, 1.16) when comparing those eligible and ineligible for HPV vaccination. This study found no evidence that HPV vaccination eligibility is associated with reporting short-term adverse effects among adolescent girls.

The impact of government support on rural grocery stores—A regression discontinuity approach

The impact of government support on rural grocery stores—A regression discontinuity approach

Effect of age-related premium readjustment on health insurance cancellation in Brazil: Regression discontinuity approach.

Age is one of the most relevant observable risk attributes in determining the value of health insurance premiums. Empirical evidence indicates that the cost of health insurance is the leading cause of contract switching, which can compromise access to healthcare services and potentially result in treatment discontinuities. Using data from a Health Maintenance Organization in the Southern region of Brazil, we examined the effect of health plan price readjustment resulting from changes in the beneficiary's age group on disenrollment or switches to a more limited coverage plan. The estimates were obtained using the method of regression discontinuity. The main findings indicate that for age group transitions at 59years old, the price readjustment effect led to an increase in contract cancellations and switching to cheaper plans. These findings highlight that an important consequence of the difference in premium sensitivity among age groups is that the exit of individuals from the health insurance sector is selective in age. The results of this paper can support policymaking to improve access to health insurance.

H(div)-conforming and discontinuous Galerkin approach for Herschel–Bulkley flow with density-dependent viscosity and yield stress

This paper presents a comprehensive study on Herschel–Bulkley flow, where the flow parameters are dependent on the density. The Herschel–Bulkley model is a generalized power-law model used to simulate viscoplastic fluids defined by a plasticity threshold. We consider the case where the plasticity threshold and the viscosity depend on the shear rate and fluid density. To analyze this model, we use a Huber regularization of the stress and propose an H(div)-conforming and discontinuous Galerkin (DG) numerical approximation for the coupled equations governing the flow. We discuss the stability and existence of discrete solutions and propose a semismooth Newton linearization for the numerical solution of the discretized system. Our numerical scheme is validated through several experiments that explore the behavior of Herschel–Bulkley flow under different conditions. The results demonstrate the robustness of our numerical method.

Can Property Taxation Fix China’s Housing Market?: A Regression Discontinuity Analysis

How does the housing market respond to a newly imposed value-based property tax? Based on individual property transaction data spanning seven years, we investigate the repercussions of a new property tax on the local housing market in Chongqing, China. In particular, we adopt a fuzzy regression discontinuity approach to examine the impact of the tax policy on house prices, transaction volumes, and the broader social welfare. We find that the property tax in Chongqing has not caused a reduction in house prices, but it has made a non-trivial contribution to local public finance for public housing programs. Our findings suggest that the property-tax-capitalization hypothesis is not supported in Chongqing’s context, although the tax improves wealth redistribution.

Herpes zoster vaccination and new diagnoses of dementia: A quasi-randomized study in Australia.

Increasing evidence suggests that neurotropic herpesviruses could play a role in the development of dementia, possibly through a neuroinflammatory process. Herpes zoster (HZ) vaccination has been reported to lead to a reduced probability of being diagnosed with dementia in several correlational studies and in a prior analysis by our team in Wales. This present study constitutes the first investigation to use a quasi-randomized study design in an electronic health record dataset from a large and diverse nation (Australia) to aim to determine the effect of HZ vaccination on dementia. In Australia, starting on November 1 2016, live-attenuated HZ vaccination was provided for free to individuals aged 70 to 79 years of age through primary care providers. Thus, those whose 80th birthday was just a few days prior to November 1 2016 never became eligible, whereas those whose 80th birthday was just a few days later were eligible. The key advantage of our approach is that one would not expect that these population groups who differ in their age by only a minute degree would, on average, differ in any of their health characteristics and behaviors. We used detailed primary healthcare records with week-of-birth information from 65 general practices across Australia. We analyzed our data using a regression discontinuity approach. Our sample consisted of 101,219 patients. As expected, patients born just before versus shortly after the date-of-birth eligibility threshold (November 2 1936) for HZ vaccination were well-balanced in their past preventive health services uptake and chronic disease diagnoses. There was an abrupt increase of 15.7 (95% CI: [12.2 - 19.3], p < 0.001) percentage points in the probability of ever receiving HZ vaccination between patients born shortly before versus shortly after the eligibility threshold. The eligibility rules of the HZ vaccination program, thus, created comparison groups just on either side of the date-of-birth eligibility threshold who were similar to each other, except for a large difference in their probability of receiving the intervention (HZ vaccination) of interest. Eligibility for HZ vaccination (i.e., being born shortly before versus shortly after November 2 1936) decreased the probability of receiving a new dementia diagnosis over 7.4 years by 2.0 percentage points (95% CI: [0.3 - 3.7], p = 0.021). Being eligible for HZ vaccination did not affect the probability of taking up other preventive health services (including other vaccinations), nor the probability of being diagnosed with other common chronic conditions than dementia. This study provides important evidence on the potential benefits of HZ vaccination for dementia because its quasi-randomized design allows for conclusions that are more likely to be causal than those of the existing associational evidence.

From silver to platinum: The impact of frequent flier tier levels on air travellers’ behaviour

We estimate the switching costs created by tier levels, one of the main components of airline frequent flier programs, by exploiting discrete tier thresholds. We first demonstrate that travellers increase their demand to reach a higher tier level just before the end of the calendar year when tier levels are determined, but do not manipulate demand in earlier months. This allows for a novel fuzzy discontinuity approach to identify causal demand effects of higher tier levels, from which we derive the airline switching costs. While the lowest level creates only negligible switching costs, the switching costs associated with the highest tier level are in the range of 30%–41% of the price of a ticket, representing an important determinant of travel behaviour in airline markets. These results especially provide evidence of the use of tier levels to induce loyalty from high-frequency travellers for whom free flight awards alone would not create substantial switching costs.

Do Criminal Politicians Affect Firm Investment and Value? Evidence from a Regression Discontinuity Approach

Do Criminal Politicians Affect Firm Investment and Value? Evidence from a Regression Discontinuity Approach

Investigation on dynamic mechanism of fault slip and casing deformation during multi-fracturing in shale gas wells

Fracturing horizontal well casing deformation has become very prominent, particularly in tectonic stress-concentrated shale gas fields, limiting the efficient development progress of shale gas. The main failure mode of casing shearing deformation had been attributed to fault slip caused by multi-fracturing. The current research did not provide a clear picture of the dynamic evolution relationship between hydraulic fracturing, fault slip, and casing deformation. In this paper, the dynamic model of fault slip induced by formation pressure change is established, incorporating the effects of stress drop, physical change of friction, and casing and cement-sheath resistance loads. The discontinuous displacement approach and explicit/implicit coupling iteration methods are used to reveal the relationships between the effective normal stress, shear stress, friction coefficient, and sliding velocity during the fault slip process. Furthermore, the microscopic process of casing deformation sheared by fault slip is investigated using static equilibrium theory, and a characterization method for determining the amount casing deformation caused by real-scale fault slip is proposed. The results show that three stages exist in the process of casing deformation sheared by fault slip, including trigger activation stage, accelerated slip stage, and deceleration slip stage. Fault slip is clearly influenced by fault strike. To reduce the amount of fault slip, the fault direction with the maximum in-situ stress should be avoided as much as possible. Serious casing deformation still occurs for large-scale activated faults even though the optimization measure of wellbore structure has been well taken. To fundamentally reduce the possibility of casing shear deformation, it is necessary to prevent fault slip through optimizing the design of hydraulic fracturing. This study lays the theoretical groundwork for the casing deformation control method in shale gas wells.

Efficiency analysis of discontinuous Galerkin approaches for the application onto quantum Liouville-type equations

The simulation of nanodevices is computationally inefficient with current algorithms. The discontinuous Galerkin approach has been demonstrated in the field of computational fluid dynamics to deliver high order accuracy and efficiency due to its reliance on matrix–vector multiplications. Previously, the discontinuous Galerkin approach was successfully used in conjunction with the finite volume technique to solve the Liouville–von Neumann equation in center-mass coordinates and thus simulate nanodevices. To exploit its full potential regarding high-performance computing, this work aims to substitute the aforementioned finite volume technique with the discontinuous Galerkin method. To arrive at the said formalism, a finite element method is implemented as an intermediate step.

Embedded Finite Element formulation for fluid flow in fractured porous medium

The presence of discontinuities, such as fractures or geological faults, can significantly influence the fluid flow in a porous medium. In general, the discontinuities can act as preferential flow paths. However, depending on their aperture and filling material, they can act as barriers to fluid flow. To model these different possibilities, this paper presents an embedded approach in the context of the finite element method to model the presence of discontinuities inside a porous medium in transient analyses. The formulation is attractive since it does not require the mesh used to discretize the porous medium to conform to the discontinuities. The derivation of the formulation is based on the Strong Discontinuity Approach by enriching the pressure field of the finite element with a Heaviside function. The enriched part of the pressure field is discretized based on the pressure jumps evaluated at the nodes where the discontinuity intersects the finite element. The discontinuity internal pressure is taken as an independent field, allowing the modeling of high pressures inside the discontinuity. A strategy to condense the discontinuity internal pressure degrees of freedom is presented. Numerical examples are presented showing the flexibility of the formulation to capture the influence of discontinuities on the fluid flow in porous medium. The results obtained with the proposed formulation are compared with interface element models, showing a good agreement between the two approaches.