Variables Approach Research Articles

Exact solutions of time-delay integer- and fractional-order advection equations

Transport phenomena play a vital role in various fields of science and engineering. In this work, exact solutions are derived for advection equations with integer- and fractional-order time derivatives and a constant time-delay in the spatial derivative. Solutions are obtained, for arbitrary separable initial conditions, by incorporating recently introduced delay functions in a separation of variables approach. Examples are provided showing oscillatory and translatory behaviours that are fundamentally different to standard propagating wave solutions.

Do Gender Differences in Mental Health Contribute to Gender Differences in Physical Health? An Instrumental Variables Approach

AbstractExisting research indicates that gender disparities in mental health contribute to gender disparities in physical health. However, the observed relationship might be driven by the endogeneity of mental health. By combining high‐quality panel data with standard estimation techniques, we initially confirm the previous findings. In contrast, when we account for the endogeneity of mental health using the death of a relative and the death of a spouse as instruments, we observe a change in the existing result. Although the positive and significant impact of mental health on physical health persists, the disparity between women and men becomes negligible.

How spousal cognitive functioning affects the level of depression in middle-aged and older adults: An instrumental variable study based on CHARLS in China.

A better understanding of the causal relationship between spousal cognitive functioning and depression levels among middle-aged and older adults is vital for effective health policymaking under the globally severe aging challenge. However, the related evidence is often limited by potential omitted-variable bias and reverse causation. This study uses an instrumental variables approach, namely the two-stage least squares (2SLS) method, to examine the impact of spousal cognitive functioning on depression levels among middle-aged and older adults in China. The data were sourced from the China Health and Retirement Longitudinal Study (CHARLS) of 2020, including a total of 3,710 couples aged 45 years and above. Depression levels were measured using the Center for Epidemiologic Studies Depression Scale (CES-D-10), while cognitive functioning was assessed using the Mini-Mental State Examination (MMSE). Spousal social participation was employed as the instrumental variable to address omitted-variable bias and reverse causation. Additionally, an interaction effect test between gender and spousal cognitive functioning was conducted. The results show that for each one-point increase in the spouse's MMSE score, the CES-D-10 score of middle-aged and older adults decreased by 17.1% to 68.2%. The OLS results indicated that women, rural residents, and middle-aged individuals were more sensitive to these changes. The interaction effect test results confirmed that women were more affected by changes in spousal cognitive functioning. However, after a more reliable 2SLS analysis, the results for age groups shifted, showing that middle-aged individuals were more sensitive to these changes, with a decrease in depression levels reaching 70.0%, compared to 60.2% for the elderly group. Nonetheless, given the prevalence of depression among the elderly, the impact of spousal cognitive decline on depression in this group should not be overlooked. Our findings highlight the importance of spousal cognitive health in managing depression among both middle-aged and older adults, with particular attention to women and rural populations.

Phase velocity of love waves as function of heterogeneity and void parameter

The present study looks at the Love wave propagating through an elastic layer containing empty pores situated above a heterogeneous elastic semi-infinite space. We have constructed separate formulations of equations of motion for both media under congruous boundary conditions. The separation of variables approach is used to build the phase velocity frequency relation in compact form using the Whittaker function. The resulting closed-form dispersion equation matches the conventional Love wave equation when heterogeneity has been removed. The propagation of Love waves is strongly influenced by a porous layer of limited thickness across an elastic semi-infinite space. Three wave fronts are demonstrated to have the potential to propagate. The equilibrated inertia and the variation in the void volume fraction are related to two wave fronts that are connected to the characteristics of the void pores. Numerical treatments are applied and graphically illustrated to implement these effects associated to Love waves’ phase velocity.

Internet use and household financial market participation: evidence from China

ABSTRACT This paper examines the effect of internet use on household financial market participation and its underlying mechanism. Using data from the 2018 China Family Panel Studies (CFPS), we find that households with internet use are 4.7% more likely to participate in financial market investments than those without. The finding remains robust after accounting for endogeneity concerns using the instrumental variables approach and a fresh double machine learning approach. We highlight the phenomenon of ‘digital divide’ that the positive effects of internet use on making financial investments are more substantial among families living in economically developed regions, and families with higher income and education levels than their counterparts. We identify three novel mechanisms through which internet use affects household investment decision-making, namely the internet information mechanism, the internet social mechanism, and the internet enabling mechanism. These findings suggest that expanding digital infrastructure building and increasing the number of internet users are important ways to enhance households’ participation in financial markets.

Impact of skilled nursing facility quality on Medicare beneficiaries with dementia: Evidence from vacancies.

People living with dementia are less likely to be admitted to high-rated nursing homes than people without dementia, despite their increased care needs. We investigated the effect of admission to nursing homes with higher staffing ratings on adverse outcomes for individuals with and without dementia post-hospitalization. Among Traditional Medicare beneficiaries discharged to nursing homes between 2011 and 2017, we examined the relationship between facility staffing star-ratings and short-term readmission and mortality using an instrumental variables approach to account for selection bias. The instrumental variables were the number of nearby vacant beds in high-rated facilities. Admission to a higher-rated nursing home lowered post-discharge mortality risk at 90 days and reduced 30- and 90-day readmission. Point estimates were larger for people with dementia. Findings underscore the need for enhancing direct care staffing in nursing homes and addressing access disparities, particularly for individuals with dementia who benefit significantly from high-quality care. We assessed how admission to nursing homes with higher staffing ratings impacted outcomes for individuals with and without dementia by exploiting variation in local bed vacancies as a source of quasi-random assignment. For both persons with and without dementia, adjusted short-term mortality and readmission rates were lower among those discharged to nursing homes with higher staffing ratings. Effects were larger for persons with dementia, indicating welfare loss from inequitable access to higher-rated nursing homes. Increasing staffing in nursing homes and reducing disparities for persons with dementia is essential for enhancing both equity and value.

Boundary Element Method for Viscous Flow through Out-phase Slip-patterned Microchannel under the Influence of Inclined Magnetic Field

Abstract In this paper, we investigate the impact of an inclined magnetic field of uniform intensity on viscous, incompressible pressure-driven Stokes flow through a slip-patterned, rectangular microchannel using the boundary element method based on the stream function-vorticity variables approach. The present investigation focuses only on the out-phase slip patterning of the microchannel walls. We address two scenarios of slip patterning, specifically large and fine slip patterning, which are determined by the periodicity of the patterning. We utilized the no-slip and Navier’s slip boundary conditions in an alternative manner on the walls. The Stokes equations govern the viscous flow through a microchannel. We assume a very small magnetic Reynold’s number to eliminate the equation of induced magnetic field in the present study. We analyzed the impact of considered dimensionless hydrodynamic parameters, including the Hartman number (Ha), inclination angle (θ) of the magnetic field, and the slip length (ls ) on fluid dynamics. In the case of fine slip, we observed significant variations in both velocity and pressure gradient, in contrast to large slip patterning. Fine slip patterning significantly increases the shear stress at slip regimes, while large slip periodicity significantly reduces it at no-slip regimes. The present investigation has several notable implications, such as regulation and advancement of mixing and heat transmission within microfluidic systems.

Adoption of green production technologies by farmers through traditional and digital agro-technology promotion–An example of physical versus biological control technologies

Traditional and digital agro-technology promotion are two critical methods for disseminating agricultural technology information, which effectively encourages farmers to employ green production technologies. This paper empirically examines the effects of traditional and digital agro-technology promotion on the adoption of green production technologies by 619 apple producers in the primary apple production area of Guanzhong Plain, China, using micro-survey data. The study's findings suggest that both promotion models significantly influence the adoption of green production technologies by farmers. This conclusion remains valid after the instrumental variables approach and a series of robustness tests are implemented to address endogeneity concerns. The heterogeneity analysis revealed that the impact of the two promotion modes on the adoption behavior of green production technologies by farmers varied by scale. Specifically, digital agro-technology promotion had a greater impact on the adoption of physical control technologies by small-scale farmers, while traditional agro-technology promotion had a greater impact on the adoption of biological control technologies by large-scale households. In addition, the technological differences between traditional agrotechnology promotion and digital agrotechnology promotion result in clear complementary and substitution effects. The two modes of promotion have evident complementary effects for biological control technologies. The two modalities of promotion for physical control technologies exhibit complementary effects between social communication-type promotions and traditional agro-technology promotions, as well as substitution effects between short-video promotions and traditional agro-technology promotions.

Do investor reactions to merger announcements shape the writing of SEC filings?

The way filings of mergers and acquisitions (M&A) with the Security Exchange Commission (SEC) are written might depend on investor reactions to initial public announcements of the deal. We examine this investor feedback hypothesis by focusing on the readability and timing of a large sample of SEC documents. We show that acquirers write documents with lower readability and file them faster when investors react negatively to the deal announcement, a finding consistent with strategic obfuscation efforts. The results are robust to alternative empirical choices, such as controlling for deal complexity or the firm's writing style. They are also confirmed using an instrumental variables approach.

Assessing the Impact of Federal Reserve Policies on Equity Market Valuations: An Instrumental Variables Approach

This study investigates the impact of Central Bank interventions on the pricing dynamics of select stock markets. The research utilizes the instrumental variables three-stage least square (3SLS) model approach. It analyses the effects of variations in the Federal Reserve’s balance sheet size across three distinct intervention scenarios: the 2008–2013 Great Recession, the 2020–2021 COVID-19 pandemic periods, and an overarching analysis spanning these timelines. Our methodology includes estimations of the Seemingly Unrelated Regression Equations (SURE), and the results are robust under the two-step Generalized Method of Moments (GMM). Our findings indicate that changes in the size of the Fed’s balance sheet correlate significantly with the pricing of principal U.S. equity market indices. This correlation reflects a time-dependent effect emanating from the Fed’s balance sheet expansion, marking a growing divergence between the adaptability of pricing mechanisms in equity and debt markets. Notably, the Federal Reserve’s interventions during the COVID-19 crisis are associated with an increase of approximately 0.0403 basis points per billion in treasury yields. This research makes a significant contribution to the understanding of financial asset pricing, particularly by elucidating the extent to which interventions in government debt securities engender price distortions in certain equity markets.

Stokes flow past an array of circular cylinders through slip-patterned microchannel using boundary element method

Two-dimensional viscous incompressible, pressure-driven, creeping flow at low Reynold's number (Re ≪ 1) around a series of circular cylinders in a slip-patterned rectangular microchannel is investigated numerically by using the boundary element method (BEM) based on a non-primitive variables approach. The non-primitive variables approach refers to the combination of stream function and vorticity variables. The Stokes equations are used to govern the flow of creeping fluid through a microchannel. We consider the alteration of the slip on both the upper and lower surfaces of the microchannel maintain the same phase (i.e., in-phase configuration). Here, the slip boundary condition refers to Navier's slip boundary condition. We considered both small as well as large patterned slip on both surfaces of the microchannel. Moreover, we have assumed that a number of cylinders of equal diameter are present in the in-line configuration in the path of flow. We studied streamlines, velocity profiles, pressure gradients, and the shear stresses with varied slip-length, and the radius of the cylinder, to get a complete comprehension of flow dynamics. We observed that the velocity and shear stress profiles exhibit significant variability in the case of fine slip patterning. Additionally, the proposed investigation holds several potential applications, such as drug capsule delivery systems, hemodynamics, bio-MEMS technology, and so forth.

Analytical solutions for the advective–diffusive ice column in the presence of strain heating

Abstract. A thorough understanding of ice thermodynamics is essential for an accurate description of glaciers, ice sheets and ice shelves. Yet there exists a significant gap in our theoretical knowledge of the time-dependent behaviour of ice temperatures due to the inevitable compromise between mathematical tractability and the accurate description of physical phenomena. In order to bridge this shortfall, we have analytically solved the 1D time-dependent advective–diffusive heat problem including additional terms due to strain heating and depth-integrated horizontal advection. Newton's law of cooling is applied as a Robin-type top boundary condition to consider potential non-equilibrium temperature states across the ice–air interface. The solution is expressed in terms of confluent hypergeometric functions following a separation of variables approach. Non-dimensionalization reduces the parameter space to four numbers that fully determine the shape of the solution at equilibrium: surface insulation, effective geothermal heat flow, the Péclet number and the Brinkman number. The initial temperature distribution exponentially converges to the stationary solution. Transient decay timescales are only dependent on the Péclet number and the surface insulation, so higher advection rates and lower insulating values imply shorter equilibration timescales, respectively. In contrast, equilibrium temperature profiles are mostly independent of the surface insulation parameter. We have extended our study to a broader range of vertical velocities by using a general power-law dependence on depth, unlike prior studies limited to linear and quadratic velocity profiles. Lastly, we present a suite of benchmark experiments to test numerical solvers. Four experiments of gradually increasing complexity capture the main physical processes for heat propagation. Analytical solutions are then compared to their numerical counterparts upon discretization over unevenly spaced coordinate systems. We find that a symmetric scheme for the advective term and a three-point asymmetric scheme for the basal boundary condition best match our analytical solutions. A further convergence study shows that n≥15 vertical points are sufficient to accurately reproduce the temperature profile. The solutions presented herein are general and fully applicable to any problem with an equivalent set of boundary conditions and any given initial temperature distribution.

Algorithmic trading and mini flash crashes: Evidence from Austria

We use stock-day level data on the market share of algorithmic trading to analyze whether algorithmic trading affects the frequency of mini flash crashes in the Austrian stock market. We use an instrumental variables approach and the Petrin and Train (2010) control function approach to address endogeneity concerns. We find no evidence that algorithmic trading significantly affects the probability of the occurrence of mini flash crashes.

NCAA football coach compensation and non-price competition for football players

ABSTRACT College football coach salaries at big-time programmes have increased substantially in recent years. We investigate non-price competition for incoming athletes as a source of salary increases. The NCAA cartel ensures that athletes receive compensation limited to the cost of attending college, which prevents football programmes from competing for athlete’s services on a price (compensation) basis. Non-price competition frequently emerges under these conditions. We develop evidence that increases in head football coach salaries cause increased football recruiting success using an instrumental variables approach to control for correlation between salaries and unobservable institution-specific factors affecting recruiting success. Results from a sample of 90 FBS schools over the period 2006–2015 support the presence of non-price competition for college football players. Each $1 million increase in head coach salary increases the quality of the incoming class of football recruits by about one standard deviation.

Paying for advance care planning in medicare: Impacts on care and spending near end of life

Spending at end of life (EOL) accounts for a large and growing share of healthcare expenditures in the US, and often reflects aggressive care with questionable value for dying patients. Using a novel instrumental variables approach, we conduct the first study on the causal effect of Medicare reimbursement for advance care planning (ACP)—the process of discussing and recording patient preferences for goals of care—on care utilization, spending, and mortality outcomes for critically ill Medicare patients. We find that billed ACP services substantially increase hospice use and hospice spending within a year, accompanied by corresponding increase in one-year mortality. The impacts of ACP services on hospice use and spending are especially prominent among patients with dementia and those of lower socioeconomic status. Among decedents, death is significantly less likely to occur in the hospital, and total and inpatient spending within the last 30 days of life fall significantly. Our findings suggest that paying for ACP services can be effective in improving hospice use for critically ill Medicare patients, with the (possibly intended) consequence of increased one-year mortality.

Seismic correlation coefficient evaluation for the application of separation of variables approach in fragility assessment

Seismic correlation can affect seismic probabilistic risk assessment results when components within the system have similar dynamic characteristics. While the fragility assessment methodology is well established, researches to evaluate and apply seismic correlation in fragility are still in progress. In this study, the seismic correlation coefficient (SCC) was quantitatively analyzed based on fragility assessment methods. In order to evaluate the SCC of several random variables associated with structure response in fragility assessment, a numerical analysis model of the structure was constructed and statistical analysis of the numerical results was performed. The SCC of the floor responses of the structural model considering random variables was evaluated from two perspectives. The first perspective involved applying variables individually or simultaneously when performing probabilistic structural analysis. The second perspective aimed to assess whether simplification of the structural analysis model affects the SCC. For this purpose, SCCs were calculated for each method and applied to a simplified failure sequence model to compare the combined fragility curves. The results of this study demonstrate the applicability of separation of variables method to the evaluation and generalization of the SCC for random variables of the fragility curve.

Fiscal rules, capital controls, and cross-border financial integration

This paper shows that adopting fiscal rules (FRs) decreases the use of capital controls and increases cross-border financial integration. This result is robust to alternative measures of fiscal rules, capital controls, and international financial integration — it is also robust to alternative econometric approaches. It also shows that the adoption of fiscal rules increases financial integration. This paper innovatively employs a formal instrumental variables (IV) approach to tackle the endogeneity of the decision to adopt fiscal rules. The adoption of FRs is instrumented using the age dependency ratio (ADR). This strategy is particularly effective because adopting FRs is more likely when the ADR is relatively low, a finding well established in the empirical literature. Governments impose capital controls to channel domestic savings into the public sector, finance their excessive fiscal deficits, and reduce their borrowing costs. However, the uncertainty over the government's future fiscal policies may lead to capital flight. FRs ‘tie the hands’ of governments and induce them to commit themselves to fiscal discipline. Moreover, FRs can also reduce the government's borrowing costs. These effects of FRs render capital controls less necessary and lead policymakers to lift capital controls, resulting in higher cross-border financial integration.

Influence and mechanisms of perceived information disclosure in shaping public attitudes towards waste disposal facilities: Evidence from China

Waste disposal facilities are an indispensable infrastructure for modern urban development, and increasing public acceptance of such facilities contributes to sustainable urban development. Estimation results using the least squares method, based on widely representative questionnaire data, indicate that perception of government information disclosure has a significant positive impact on enhancing the public’s willingness to accept waste disposal facilities. This finding is further confirmed not only when using instrumental variables approach to address potential endogeneity as well, but also by a series of robustness tests. The results of the heterogeneity analyses show that the positive impact of government information disclosure is present only in the sub-sample of those who have no religious trust and frequency of online socialization. Further findings support the idea that political trust and the perception of the government capacity to ensure public security are two fundamental mechanisms. In particular, trust in county government and perceptions of medical security are more likely to drive this positive effect. This study reveals the role of perceptions about information disclosure in shaping public attitudes toward public programs and provides new insights into facilitating the successful construction of public facilities.

Marketing Outcomes and Shareholder Value: A Review and Research Agenda

One of the most fundamental management questions is how market-based assets affect shareholder value. To provide an answer, we review the extensive literature on marketing outcomes and shareholder value using the Theory, Context, Characteristics, and Methodology (TCCM) framework. The analysis reveals that researchers mainly rely on the efficient market hypothesis, signaling theory, and market-based arguments to theorize the relationship between customer-based market assets and shareholder value. Researchers predominantly collect secondary data and employ event study, persistence methods, and instrumental variables approach to show that marketing actions (such as advertising and brand building) and customer-based market assets (such as customer satisfaction, customer loyalty, and brand equity) positively influence shareholder value. After outlining the findings, future research directions on the relationship between market assets and shareholder value are explored.

Imports, Exports, and Employment: India’s Trading Relationship with China

This paper examines the effect of increased import competition and export demand on local labour markets in the context of India’s trading relationship with China. Using an instrumental variables approach, I find that Indian districts exposed to Chinese imports experience decreased manufacturing employment growth relative to their positive pre-existing trend with no offsetting adjustment in services employment or population. The negative employment effect of imports is greater for large establishments. On average, manufacturing employment does not grow in response to export demand shocks, but districts with sufficient development, density, or access to Chinese markets see increased manufacturing employment in response to Chinese export demand.