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The purpose of this paper is to analyze numerically the blowup in finite time of the solutions to a one-dimensional, bidirectional, nonlinear wave model equation for the propagation of small-amplitude waves in shallow water, as a function of the relaxation time, linear and nonlinear drift, power of the nonlinear advection flux, viscosity coefficient, viscous attenuation, and amplitude, smoothness and width of three types of initial conditions.

An implicit, first-order accurate in time, finite difference method valid for semipositive relaxation times has been used to solve the equation in a truncated domain for three different initial conditions, a first-order time derivative initially equal to zero and several constant wave speeds.

The numerical experiments show a very rapid transient from the initial conditions to the formation of a leading propagating wave, whose duration depends strongly on the shape, amplitude and width of the initial data as well as on the coefficients of the bidirectional equation. The blowup times for the triangular conditions have been found to be larger than those for the Gaussian ones, and the latter are larger than those for rectangular conditions, thus indicating that the blowup time decreases as the smoothness of the initial conditions decreases. The blowup time has also been found to decrease as the relaxation time, degree of nonlinearity, linear drift coefficient and amplitude of the initial conditions are increased, and as the width of the initial condition is decreased, but it increases as the viscosity coefficient is increased. No blowup has been observed for relaxation times smaller than one-hundredth, viscosity coefficients larger than ten-thousandths, quadratic and cubic nonlinearities, and initial Gaussian, triangular and rectangular conditions of unity amplitude.

The blowup of a one-dimensional, bidirectional equation that is a model for the propagation of waves in shallow water, longitudinal displacement in homogeneous viscoelastic bars, nerve conduction, nonlinear acoustics and heat transfer in very small devices and/or at very high transfer rates has been determined numerically as a function of the linear and nonlinear drift coefficients, power of the nonlinear drift, viscosity coefficient, viscous attenuation, and amplitude, smoothness and width of the initial conditions for nonzero relaxation times.

It is extremely difficult to establish a variational principle for plasma. Kalaawy obtained a variational principle by using the semi-inverse method in 2016, and Li and He suggested a modification in 2017. This paper aims to search for a generalized variational formulation with a free parameter.

The semi-inverse method is used by suitable construction of a trial functional with some free parameters.

A modification of Li-He’s variational principle with a free parameter is obtained.

This paper suggests a new approach to construction of a trial-functional with some free parameters.

Fractional order nonlinear evolution equations (FNLEEs) pertaining to conformable fractional derivative are considered to be revealed for well-furnished analytic solutions due to their importance in the nature of real world. In this article, the autors suggest a productive technique, called the rational fractional (DξαG/G)-expansion method, to unravel the nonlinear space-time fractional potential Kadomtsev–Petviashvili (PKP) equation, the nonlinear space-time fractional Sharma–Tasso–Olver (STO) equation and the nonlinear space-time fractional Kolmogorov–Petrovskii–Piskunov (KPP) equation. A fractional complex transformation technique is used to convert the considered equations into the fractional order ordinary differential equation. Then the method is employed to make available their solutions. The constructed solutions in terms of trigonometric function, hyperbolic function and rational function are claimed to be fresh and further general in closed form. These solutions might play important roles to depict the complex physical phenomena arise in physics, mathematical physics and engineering.

The rational fractional (DξαG/G)-expansion method shows high performance and might be used as a strong tool to unravel any other FNLEEs. This method is of the form U(ξ)=∑i=0nai(DξαG/G)i/∑i=0nbi(DξαG/G)i.

Achieved fresh and further abundant closed form traveling wave solutions to analyze the inner mechanisms of complex phenomenon in nature world which will bear a significant role in the of research and will be recorded in the literature.

The rational fractional (DξαG/G)-expansion method shows high performance and might be used as a strong tool to unravel any other FNLEEs. This method is newly established and productive.

The unprecedented economic crisis in Greece deeply affected entrepreneurship, which was traditionally characterised by low levels of innovation and competitiveness, the dominant presence of micro-sized enterprises and the weak signs of prosperity in large firms. This paper, in acknowledgement of the necessary transformations that production incurred due to the crisis, attempts to detect the characteristics of large manufacturing firms that contributed to their greater resilience during the unstable period of 2011–2016 by analysing the determinants of the higher profitability of firms. The analysis shows that firms that improved their productivity and sales levels and in parallel are flexible, in the sense that they have limited amounts of both assets and liabilities and thus a small risk, are those that presented higher profits during the period under study. Initial conditions, sectoral characteristics and the broader national environment do not seem to have a strong contributive role in firms' profitability.

The analysis follows a dynamic system generalised method of moments (GMM) estimation based on a panel data set of 125 Greek large firms over the time span 2011–2016.

The analysis shows that firms that improve their productivity and sales levels and in parallel are flexible, in the sense that they have a limited amount of both assets and liabilities and thus a small risk, are those that present higher profits during the period under study. Initial conditions, sectoral characteristics and the broader national environment do not seem to have a strong contributive role in firms' profitability.

The present paper attempts to explain the performance of the most dynamic large manufacturing firms in Greece by investigating the role of some of the most important determinants of firm profitability (according to data availability), acknowledging, however, some analysis' limitations as the absence of some other parameters like the export activity or the incorporation of any innovative features in the firms

The novelty of this paper lies in two points. First, the subject of the analysis is the large firms in Greece, which have not received much attention as Greek entrepreneurship was traditionally based on the light, labour- or resource-intensive production and the main bulk of the literature was not on that topic. Second, during the deep and protracted crisis that Greece has experienced, several production transformations have taken place that remain partly undiscovered. The present paper attempts to analyse the characteristics of large firms that drove their profitability and improved their resilience during the crucial time period 2011–16.

在希臘出現的史無前例的經濟危機深深地影響了該國的創業能力，而希臘的創業能力有其傳統特徵：低水平的創新與競爭力、微型企業佔主導地位和大企業呈現微弱的繁榮跡象。本文在承認這經濟危機導致生產必須轉型的前提下，研究那些於2011年至2016年這不穩定期間營運的大型製造公司，透過分析它們能取得更高利潤的決定因素，以探求是哪些公司特徵使其有更強的抵禦和復原能力。分析顯示，那些改善了生產率和銷售水平的公司，亦同時是靈活變通的公司 （所謂靈活變通，是指公司無論在資產抑或負債方面的數量上都是有限的，因此，它們只需冒小風險），就是那些在本研究涵蓋期間展示獲取更高利潤的公司。初始條件、行業的特徵和更廣泛的國家環境，就公司的盈利能力而言，似乎沒有扮演重要的促進角色。

分析用了廣義動差估計(GMM)這動態系統，基於涵蓋125間希臘大公司、橫跨2011年至2016年期間的面板數據。

分析顯示，那些改善生產率和銷售水平的公司，亦同時是靈活變通的公司 （所謂靈活變通，是指公司無論在資產抑或負債方面的數量上都是有限的，因此，它們只需冒小風險），就是那些在本研究涵蓋期間展示獲取更高利潤的公司。初始條件、行業的特徵和更廣泛的國家環境，就公司的盈利能力而言，似乎沒有扮演重要的促進角色。

本文擬透過探討一些決定公司盈利能力最重要的因素 （根據數據的可獲性），來闡釋在希臘那些最有動力的大型製造公司的績效，但亦同時承認分析有局限之處，那就是，分析沒有涵蓋一些其它決定因素：出口活動和那些公司有否納入任何創新功能。

本文有兩個創新之處：首先，本研究分析的對象是在希臘的大企業，而這個研究對象和課題未曾得到頗多的關注，這是因為希臘的創業能力一向基於勞動密集型或資源密集型的輕工業生產，而過去大部分文獻都不涉及這個課題。另外，當希臘經歷這個巨大且持久的危機時，國內有些仍未普遍察覺的生產轉型出現了。本文擬分析推動大企業於2011年至2016年間這關鍵時刻取得利潤，及改善其抵禦和復原能力的公司特徵。

This study investigates the dynamic causality linkages between fiscal deficits and selected macroeconomic indicators in a panel of five East African Community countries.

The research design is based on panel cointegration tests, panel cross-section dependence tests, panel error correction-based Granger causality tests and panel impulse response functions.

Results show that there is long-run feedback causality among fiscal deficits and each of the variables include gross domestic product (GDP) growth, current account balance, interest rates, inflation, grants and debt service. Short-run Granger causality dynamics indicate that there is feedback causality between fiscal deficits and GDP growth; no causality between fiscal deficits and inflation; no causality between fiscal deficits and current account; no causality between fiscal deficits and interest rates; feedback causality between fiscal deficits and grants; and no causality between fiscal deficits and debt service. Impulse response functions show positive and significant impacts of current account balance, inflation and grants; negative and significant impacts of real GDP growth and lending rates; and insignificant effects of debt service.

While the study examines the dynamic causality between fiscal deficits and selected macroeconomic indicators in the East African Community, the analysis excludes South Sudan due to significant data limitations.

In light of the East African Community's aspirations to achieve convergence on key macroeconomic targets, including the fiscal deficit, this research provides novel insights on fiscal policy determinants and causality dynamics.

The dynamic relationships between fiscal policy and macroeconomic variables may have social implications for welfare, equitable growth and distribution of resources.

With a focus on the East African Community, this paper contributes to the literature on the macroeconomic determinants of fiscal deficits in regional economic communities.

The purpose of this paper is to examine how a supervisor’s virtuous leadership as perceived by subordinates influences subordinates’ work-related well-being and to examine the mediating role of trust in the leader and the moderating roles of individual leader virtues and various characteristics of subordinates and organizations.

An online survey was conducted through Prolific among a self-selected sample of 1,237 employees who worked with an immediate supervisor across various industries in primarily the UK and the USA. Structural equation modeling was used to test the hypotheses.

The empirical results indicate that an immediate supervisor’s virtuous leadership as evaluated by the subordinate positively influences all three considered dimensions of work-related well-being – job satisfaction, work-related affect and work engagement – for a wide variety of employees in different industries and countries. A subordinate’s greater trust in the supervisor fully mediates this positive influence for job satisfaction and work engagement and partially for work-related affect. All five individual core leader virtues – prudence, temperance, justice, courage and humanity – positively influence work-related well-being.

The findings underscore that promoting virtuous leadership is a promising pathway for improved employee well-being, which may ultimately benefit individual and organizational performance.

Despite an age-old interest in leader virtues, the lack of consensus on the defining elements of virtuous leadership has limited the understanding of its consequences. Building on recent advances in the conceptualization and measurement of virtuous leadership and leader character, this paper addresses this void by exploring how virtuous leadership relates to employees’ well-being and trust.