Homogeneous Panel Research Articles

Tetrahedral core sandwich panels behavior under bending loading

Abstract Sandwich panel with complex core structure could be represented as a homogenous panel with anisotropic mechanical properties to describe the behavior at the macro level. Effective physical and mechanical characteristics were determined, representing the body as a homogeneous anisotropic continuum. The results of the numerical analysis of sandwich panels in case of bending were performed using ANSYS software. The effective elastic characteristics analysis for the periodicity cell of a sandwich panel shows that, to describe the stress-strain state of a panel with a similar tetrahedral core at the macro level, in addition to the orthotropic behavior in the panel plane, different elastic behavior occurs under tension and compression.

Impacts of R&D and advertising intensities on ROE and Tobin’s Q of selected US IT firms

This paper investigates the effects of advertising and R&D intensities on ROE and Tobin’s Q of five selected US IT firms. These companies are selected for complete availability of data over 1986-2019. Data are obtained from COMPUSAT. The time series and the cross-sectional data have been combined together to create a homogenous panel within the same IT sector. The data distributions appear to be near-normal. ROE is mildly negatively correlated with both advertising and R&D intensities. Tobin’s Q is mildly positively correlated with them. In both cases, the effects are mixed. For ROE, the net effect is negative in term of the sum of the slope coefficients. Likewise, it is positive for Tobin’s Q. Keywords: Advertising, R&D, Pooled OLS, ROE, Tobin’s Q. JEL Classifications: G10, G30, G39

Modeling the link between tourism and economic development: evidence from homogeneous panels of countries

Having previously analyzed the relationship between tourism and economic growth from distinct perspectives, this paper attempts to fill the void existing in scientific research on the relationship between tourism and economic development, by analyzing the relationship between these variables using a sample of 123 countries between 1995 and 2019. The Dumistrescu and Hurlin adaptation of the Granger causality test was used. This study takes a critical look at causal analysis with heterogeneous panels, given the substantial differences found between the results of the causal analysis with the complete panel as compared to the analysis of homogeneous country groups, in terms of their dynamics of tourism specialization and economic development. On the one hand, a one-way causal relationship exists from tourism to development in countries having low levels of tourism specialization and development. On the other hand, a one-way causal relationship exists by which development contributes to tourism in countries with high levels of development and tourism specialization.

The predictive capacity of polygenic risk scores for disease risk is only moderately influenced by imputation panels tailored to the target population.

Polygenic risk scores (PRSs) predict individuals' genetic risk of developing complex diseases. They summarize the effect of many variants discovered in genome-wide association studies (GWASs). However, to date, large GWASs exist primarily for the European population and the quality of PRS prediction declines when applied to other ethnicities. Genetic profiling of individuals in the discovery set (on which the GWAS was performed) and target set (on which the PRS is applied) is typically done by SNP arrays that genotype a fraction of common SNPs. Therefore, a key step in GWAS analysis and PRS calculation is imputing untyped SNPs using a panel of fully sequenced individuals. The imputation results depend on the ethnic composition of the imputation panel. Imputing genotypes with a panel of individuals of the same ethnicity as the genotyped individuals typically improves imputation accuracy. However, there has been no systematic investigation into the influence of the ethnic composition of imputation panels on the accuracy of PRS predictions when applied to ethnic groups that differ from the population used in the GWAS. We estimated the effect of imputation of the target set on prediction accuracy of PRS when the discovery and the target sets come from different ethnic groups. We analyzed binary phenotypes on ethnically distinct sets from the UK Biobank and other resources. We generated ethnically homogenous panels, imputed the target sets, and generated PRSs. Then, we assessed the prediction accuracy obtained from each imputation panel. Our analysis indicates that using an imputation panel matched to the ethnicity of the target population yields only a marginal improvement and only under specific conditions. The source code used for executing the analyses is this paper is available at https://github.com/Shamir-Lab/PRS-imputation-panels.

Reliability and Correlations Between Overall Severity, Roughness and Breathiness in the Perception of Dysphonic Voices: Investigating Cognitive Aspects.

this study concerns the subjective perception of the quality of the voice, more particularly in the case of dysphonia. Our general objective is to study the perceptual mechanisms, which constitute Hirano's GRBAS multidimensional perceptual rating scale. We tested the reliability of the GRB perceptual scale both in terms of test-retest reliability (intra-listener stability) and in terms of inter-listener agreement. We also studied how listeners process the three different parameters of the scale by varying the perceptual rating conditions of G, R, and B. The three attributes were rated simultaneously in one condition and in isolation in a second condition. The experiment was based on texts read by fifty dysphonic speakers. We selected five listeners specialized in voice assessment to provide perceptual judgments of the voices. Our results show that G is strongly correlated with R and/or B. When the GRB rating process is simultaneous, G is almost equal to the maximum score assigned to the R and/or B parameter (R²=0.97). Conversely, R and B are poorly correlated. While intra-listener variability was limited, inter-judge variability was important even in a homogeneous panel of judges.

Türkiye’de Bölgesel Kayıt Dışı İstihdam ve Makroekonomik Değişkenler Arasındaki Karşılıklı Dinamik İlişkiler: Bir Panel VAR Analizi

The presence of the informal economy and unregistered employment engenders adverse working conditions and job insecurity and diminishes tax revenues. Post-2000, Türkiye has placed considerable emphasis on fighting the informal economy and unregistered employment. Nevertheless, current data from the Social Security Institution reveals a 29% unregistered employment rate. Numerous factors affect the informal economy, with their impact contingent on the developmental status of economies. In Türkiye, characterized by substantial regional disparities, policymakers must account for regional heterogeneities. Within this context, an examination of the dynamic relationship between unregistered employment and key economic indicators such as growth, unemployment, and inflation in the Turkish economy is conducted using a homogeneous panel VAR model. Moreover, the study delves into gender-specific distinctions in unemployment rates and their relationship with unregistered employment. Utilizing annual data spanning 2009 to 2021 from NUTS 2 of TURKSTAT, the findings underscore the necessity for unregistered employment policies to address regional variations. Significantly, the interdependence between registered and unregistered economies underscores the guiding role of the unregistered sector within the registered economy. Hence, it is suggested that fighting unregistered employment may require a fundamental redesign of the current economic production structure to mitigate its prevalence.

Pathologists’ first opinions on barriers and facilitators of computational pathology adoption in oncological pathology: an international study

Computational pathology (CPath) algorithms detect, segment or classify cancer in whole slide images, approaching or even exceeding the accuracy of pathologists. Challenges have to be overcome before these algorithms can be used in practice. We therefore aim to explore international perspectives on the future role of CPath in oncological pathology by focusing on opinions and first experiences regarding barriers and facilitators. We conducted an international explorative eSurvey and semi-structured interviews with pathologists utilizing an implementation framework to classify potential influencing factors. The eSurvey results showed remarkable variation in opinions regarding attitude, understandability and validation of CPath. Interview results showed that barriers focused on the quality of available evidence, while most facilitators concerned strengths of CPath. A lack of consensus was present for multiple factors, such as the determination of sufficient validation using CPath, the preferred function of CPath within the digital workflow and the timing of CPath introduction in pathology education. The diversity in opinions illustrates variety in influencing factors in CPath adoption. A next step would be to quantitatively determine important factors for adoption and initiate validation studies. Both should include clear case descriptions and be conducted among a more homogenous panel of pathologists based on sub specialization.

New insights into the damage assessment and energy dissipation weight mechanisms of ceramic/fiber laminated composites under ballistic impact

Ceramics/composite laminated armor structures have become the mainstream in the design of bulletproof materials. To obtain systematic improvements in composite targets, it is essential to design the structure of each ceramic/fiber to ensure synergistic energy matching between them. However, the challenges of heavy workload and high-costs limit the experimental testing of these composites. In this report, B4C ceramics/ultra-high molecular weight polyethylene (UHMWPE) composite targets are studied and the impact of ceramic splicing size, impact position and size on the anti-elastic performance is predicted. Finite element analysis is used to comprehensively analyze critical obstacles of the failure damage, energy dissipation weight and ballistic mechanism of each material. Prediction results indicate that ceramics damage, fiber damage, and fiber delamination account for about 65%, 21%, and 14% of the total energy consumption, respectively. Square splicing and large size ceramics/fiber composites are found to have the best anti-elastic properties when the center position is impacted. This is ascribed to the transversal rapid stress wave propagation on the ceramic surface and the beneficial energy dissipation of the composite-backing arising from the longitudinal stress wave transfer of homogeneous panels. The results provide insights for identifying viable design methods for each structure, optimizing the matching of panels and backplanes, which reduces the number of experimental tests need to validate a given structure.

Testing the efficiency of emerging markets: Evidence from nonlinear panel unit tests

In this study, we investigate market efficiency considering nonlinearities by testing the weak-form market efficiency of the stock markets of Brazil, China, Russia, Turkey, and South Africa using recently proposed nonlinear panel unit root tests. The stock markets of these emerging countries are deliberately selected for their market capitalization to form a homogenous panel. The results of nonlinear models indicate that the stock market indexes are stationary and weak-form inefficient. This finding contributes to the contradictory results of the prior research using linear and nonlinear models about the efficiency of emerging stock markets in favor of nonlinear ones. Furthermore, we propose that studies using financial variables consider such nonlinearity in order to achieve more accuracy in findings related to such studies.

COMPARATIVE STUDY OF PARTICLEBOARDS WITH HEVEA BRASILIENSIS WASTE FROM DIFFERENT PRODUCTION AND MOISTURE CONFIGURATIONS

After the production cycle of latex, Hevea brasiliensistrees becomeresidual living plants for this activity, although their woody trunks are still potentially subject to industrial utilization. Bio-composites derived from rubberwood particles were manufactured using two different configurations as a strategy to examine the potential of this species with respect to mechanical behavior. Homogeneous panels were developed from particles at the saturation condition, and heterogeneous panels were obtained from dry particles conditioned at 12% moisture content. Both examples were heat-pressed and glued with castor oil-based polyurethane resin. Density, short-term water absorption and thickness swelling, modulus of rupture and modulus of elasticity in the static bending and perpendicular tensile were evaluated. Panels derived fromrubberwood particles proved to be viable according to the technical standards.

A universal elastoplastic equivalent method for sandwich panels and its application in plastic forming

Based on Hill’48 yield criterion, a simple and universal elastoplastic equivalent method for sandwich panels was proposed. In this method, the core of sandwich panel was equivalent to an orthotropic homogeneous panel, and the elastoplastic parameters of equivalent sandwich model were quickly obtained by uniaxial tensile and pure shear numerical simulations of the mesoscopic sandwich model utilizing user-defined material subroutine (UMAT). The equivalent elastoplastic parameters of brazed aluminum honeycomb panels (BAHPs) with core heights of 9 mm (BAHP-H9) and 12 mm (BAHP-H12) were obtained, which were proved to be effective by comparison with analytical solutions and analysis of numerical simulation results. Then, the effectiveness of elastoplastic equivalent method was further demonstrated by comparing the numerical simulation results of multi-point forming (MPF) for the mesoscopic and equivalent finite element (FE) model of BAHPs. Finally, MPF experiments of cylindrical BAHPs under different target forming radii were carried out. The results showed that the elastoplastic equivalent method could be effectively applied to the plastic forming of sandwich panels.

Dirty dance: tourism and environment

ABSTRACT Tourism was one of the fastest-growing sectors of the global economy before the COVID-19 pandemic, accounting for around 10% of global GDP. This has created a number of challenges including environmental degradation, especially in small island countries where the carbon footprint of tourism constitute a substantial share of carbon dioxide (CO2) emissions. This study investigates the impact of tourism on CO2 emissions in a relatively homogenous panel of 15 Caribbean countries over the period 1960–2019. The results show that international tourist arrivals have a statistically and economically significant effect on CO2 emissions, after controlling for other economic, institutional and social factors. Managing tourism sustainably requires a comprehensive set of policies and reforms aimed at reducing its environmental impact, and curbing excessive dependency on fossil fuel-based energy consumption.

Particleboards manufactured from Tectona grandis wood waste with homogeneous and three-layer heterogeneous compositions for commercial purposes

Tectona grandis wood presents decent dimensional stability as well as highly suitable physical and mechanical properties. These characteristics have encouraged the intense usage of this species, which also includes the reuse of wood processing waste for panel production. Using teak wood waste, this study aims to manufacture and evaluate heat-pressed particleboards at 5 MPa and 100 °C, by being glued with castor oil-based polyurethane resin at proportions of 10% for the homogeneous boards and 12% for the heterogeneous solutions. Single-layer (homogeneous) boards were compared with three-layer particleboard specimens (heterogeneous) having the finer particles in the outer layers. The basic density, moisture content, modulus of rupture and modulus of elasticity in the static bending and perpendicular tensile, water absorption, and thickness swelling after 24 h were evaluated to support this comparative study. All the manufactured particleboards met the standardized requirements of performance, thus being very feasible for usage as non-structural boards. When the two different compositions were analyzed, a considerably better performance of the three-layered particleboards was identified when compared to the homogeneous panels.

A bending stiffness criterion for sandwich panels with high sound insulation and its realization through low specific modulus layers

The sound transmission loss of a sandwich panel is usually much lower than that given by the mass law for a homogeneous panel with the same weight in the mass-controlled frequency range. How to make the sound transmission loss of the sandwich panel close to the mass law and maintain a high static stiffness is a key acoustic issue in its design. In this paper, the critical apparent bending stiffness is defined as the apparent bending stiffness at which the sound transmission loss of a sandwich panel approaches that of the mass law. Then, a method is given to determine the critical apparent bending stiffness of sandwich panels, based on which a range of structural parameters can be obtained to guide the design of sandwich panels with high acoustic performance. Compared with the apparent bending stiffness of a typical sandwich panel, the critical apparent bending stiffness decays more rapidly with the increase of frequency, exhibiting a relatively high static stiffness and a relatively low dynamic stiffness. In order to make the apparent bending stiffness of a typical sandwich panel close to the critical apparent bending stiffness, the concept of introducing an elastic layer with low specific modulus in the middle of the core layer is proposed. Both theoretical and experimental results show that the introduced elastic layer with low specific modulus reduces the dynamic bending stiffness of the sandwich panel while a high static bending stiffness is maintained, thus significantly improving the broadband sound-insulation performance of the panel.

A High‐Performance Sound Insulation Component for Filter Capacitors Based on Coiled‐up Acoustic Metamaterials

In the light of the spectrum characteristics of filter capacitor noise, a high-performance sound insulation component (HSIC) based on coiled-up acoustic metamaterials is developed. By efficiently absorbing harmonic components whose acoustic energy is predominant, HSIC can insulate the middle- and low-frequency noise radiated by filter capacitors significantly. Simulated results show that under the excitation of a normal incident sound wave, the sound transmission loss of HSIC is 8.0, 7.0, 6.9, and 4.3 dB higher than that of a homogeneous panel with same area density (HPSAD) at the frequencies of 400, 500, 600, and 700 Hz, respectively. The transmission loss of HSIC for filter capacitor noise is 6.4 dB(A) higher than that of HPSAD. Experimental results show that under the excitation of a diffuse sound field, HSIC still has an excellent sound insulation performance and the transmission loss for filter capacitor noise can increase by 4.5 dB(A). Furthermore, an impedance analysis and a complex frequency plane analysis are conducted to elucidate the sound insulation and absorption mechanism of HSIC.

A Note on the Transmission of Policy Uncertainty Shocks on Asia-Pacific Stock Returns

This study explores the transmission of various policy uncertainty shocks—such as financial market uncertainty (using the Chicago Board Options Exchange Volatility Index), macroeconomic policy uncertainty (using the Global Economic Policy Uncertainty), and anthropogenic uncertainty (using geopolitical risks)—to Asia-Pacific country (APC) stock returns. We adapt a homogeneous panel vector autoregressive model for the distinct analysis of emerging and advanced APCs. Our major findings are that 1) APC stocks are vulnerable to financial and macroeconomic policy uncertainty shocks but less affected by geopolitical risks and 2) the negative impacts of policy uncertainty indicators are greater and longer lasting in advanced APCs than in emerging APCs. The more resilient emerging APC stocks have diversification benefits for investors. Our findings are robust to considerations of nominal and real stock returns.

The impact of panel composition and topic on stakeholder perspectives: Generating hypotheses from online maternal and child health modified‐Delphi panels

IntroductionMultistakeholder engagement is crucial for conducting health services research. Delphi‐based methodologies combining iterative rounds of questions with feedback on and discussion of group results are a well‐documented approach to multistakeholder engagement. This study develops hypotheses about the impact of panel composition and topic on the propensity and meaningfulness of response changes in multistakeholder modified‐Delphi panels.MethodsWe conducted three online modified‐Delphi (OMD) multistakeholder panels using the same protocol. We assigned 60 maternal and child health professionals to a homogeneous (professionals only) panel, 60 pregnant or postpartum women (patients) to a homogeneous panel, and 30 professionals and 30 patients to a mixed panel. In Round 1, participants rated the seriousness of 11 maternal and child health outcomes using a 0–100 scale and explained their ratings. In Round 2, participants saw their own and their panel's Round 1 results and discussed them using asynchronous, anonymous discussion boards moderated by the study investigators. In Round 3, participants revised their original ratings. Our outcome measures included binary indicators of response changes to ratings of the low, medium and high severity maternal and child health outcomes and their meaningfulness, measured by a change of 10 or more points.ResultsParticipants changed 818 of 1491 (55%) of responses; the majority of response changes were meaningful. Patterns of response changes were different for patients and professionals and for different levels of outcome seriousness. Using study results and the literature, we developed three hypotheses. First, OMD participants, regardless of their stakeholder group, are more likely to change their responses on preference‐sensitive topics where there is a range of viable alternatives or perspectives. Second, patients are more likely to change their responses and to do so meaningfully in mixed panels, whereas professionals are more likely to do so in homogeneous panels. Third, the association between panel composition and response change varies according to the topic (e.g., the level of outcome seriousness).ConclusionsResults of our work not only helped generate empirically derived hypotheses to be tested in future research but also offer practical recommendations for designing multistakeholder OMD panels.Patient or Public ContributionPregnant or postpartum women were involved in this study.

A holistic approach for the adaptive reuse project selection: The case of the former Enel power station in Bari

The refurbishment and regeneration of unused building stock, with particular attention to the historical industrial heritage, is becoming an issue increasingly influential in the strategic choices for the development of sustainable cities. In particular, the regeneration of warehouses and historic buildings, allows to preserve the memory of past architecture characters, converting them into new functional centres within the urban structure. Adaptive reuse is an important design strategy for achieving sustainability as it ensures a continuous building life cycle and prevents buildings destruction. On the other hand, an exhaustive approach to select the best adaptive reuse project, involving many qualitative and quantitative parameters is missing in related literature. This paper proposes a holistic approach for the selection of the adaptive reuse project strategies based on a suitable index and calibrated through the application of the Optimised Analytic Hierarchy Process (O-AHP) Model. The main novelty of the proposed research is threefold: i) for the first time the importance of a large number of parameters involved in the adaptive reuse project selection has been quantified according to two different panels of experts, ii) a shared priority is demonstrated by comparing the vision of Academics and Professionals; iii) a new index is calibrated on the basis of the obtained parameters importance to support the adaptive reuse project selection of dismissed industrial areas. The proposed approach considers both qualitative and quantitative data in the analysis and is calibrated according to two homogeneous panels of 30 experts (15 Academics and 15 Professionals) in the field. In order to show the potential of the proposed index, the choice of the ideal design solution of the former Enel power plant in Bari (Italy) is individuated among six project proposal of the conversion.

Fiscal reaction functions for the advanced economies revisited

We revisit the relationship between the primary balances/GDP and debt/GDP ratios (fiscal reaction function, FRF), in the advanced economies, showing that using adequate tests and estimators leads to question the validity of the current consensus. Using data for 1961–2019, we find that long-run FRFs exist only in a small number of advanced economies (Belgium, Germany, Greece, Norway, Portugal and Sweden), with polynomial effects with fiscal fatigue only in Germany. These results warn against the widespread practice of estimating homogeneous polynomial panel FRFs. Limiting the sample to 1961–2007, thus excluding the 2008 crisis and its aftermath, FRFs hold also in Canada, Ireland, Italy (polynomial), Spain and USA, though not in Germany, and the coefficients are generally larger. Particularly, after 2008 European Union countries appear somehow to have been more likely to implement FRFs.

How policy influence varies with race and gender in the US courts of appeals

Even when women and people of color achieve positions of political power, institutional norms may combine with social constructions of difference to create a system in which power is distributed disproportionately. Such a pattern is evident in the US courts of appeals. Each case is resolved by a panel of three judges who also decide whether the opinion should be binding precedent (i.e., published) or not. I theorized that the variety of views and extended deliberation often attributed to diversity in a small-group environment depressed the rate of publication if judges were willing to compromise on the outcome but less willing to publish an opinion after such compromise. Using a massive original dataset of virtually all dispositive circuit opinions from 2002 to 2012, I found that homogeneous panels (98% of which are composed of white men) shaped policy more frequently than diverse panels.