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Orthopaedic implants, such as intervertebral disc endoprostheses (IDEs) are difficult to manufacture by means of conventional methods because of their complex shape. However, technologies developed in recent years, such as selective laser melting, could simplify this process. Although this method is attractive in both manufacturing and rapid prototyping of IDEs, little is known about their tribological performance. The functional aim of the work is to conduct a tribological evaluation of the ASTM F75 alloy after selective laser melting process and to investigate the viability of the technology in IDE design. The research aim was an explanation of the wear mechanism of bearing surfaces with respect to the reference material.

In this paper, the tribological test results of a lumbar IDE prototype fabricated by selective laser melting and forging is presented and compared. The endoprostheses were fabricated from commercially available ASTM F75 powder using a selective laser melting device. As a reference material, a forged ASTM F1537 LC alloy was used. Comparative wear and friction tests were carried out with the use of a unique spine simulator.

The obtained results confirm the viability of the selective laser technology in endoprosthesis design. Unfortunately, poorer tribological wear resistance of endoprostheses produced by means of selective laser melting (SLM) technology compared with that of the reference material calls into question the possibility of using these technologies in the manufacturing process of endoprosthesis' components exposed to tribological wear.

This paper presents the friction and wear behaviour of the lumbar IDE prototype. The tests were carried out in motion and loading conditions close to those we observe in the lumbar spine.

The purpose of this paper is to analyse the market reaction to the appointments of chief executive officers (CEOs) in companies listed on the Warsaw Stock Exchange. The authors focussed on the relationship between the characteristics of a newly appointed CEO and the shareholders’ reactions to the appointment of a CEO.

To measure shareholder reaction, the authors apply an event study methodology. The determinants of reaction are identified on the basis of multi-regression analysis.

The results reveal a negative market reaction to all CEO appointments, both new appointments and reappointments. Investor reaction is driven more by the financial condition of the company, the company’s market performance and the free float, than by the characteristics of a newly appointed CEO. Neither the origins and generation (age) nor the gender of a CEO influence share prices. The relationship between the educational background of a CEO and shareholders’ reactions is mixed. Furthermore, the appointment of an inexperienced CEO seems to be preferred by investors.

The study is restricted by certain limitations related to the adopted measures, the single-market research, data gaps and the selection of variables for regression analysis. A further cross-country study including Central and Eastern Europe and/or the transition economies of the Baltic Region is recommended. The relationship between the operating performance of a firm and its internal control mechanisms could be explored.

The findings might influence the decisions made by company owners and supervisory boards when appointing top executives, and might contribute to a better understanding of how CEO appointments can affect shareholder value creation. The results also provide important guidelines for institutions that oversee the financial system.

The findings of this study are expected to the findings are expected to contribute to the literature on the empirical analysis of the shareholder wealth effect, on signalling theory, on the phenomenon of information asymmetry and on corporate governance. The study covers a full economic cycle of the capital market, including the financial crisis and financial bubbles, and it fills a gap in the research regarding emerging markets and transition economies in Europe.

The paper aims to present the advanced mathematical and numerical models of conjugated heat and mass transfer in a multi-layer protective clothing, human skin and muscle subjected to incident external radiative heat flux.

The garment was made of three layers of porous fabric separated by the air gaps, whereas in the tissue, four skin sublayers and muscle layer were distinguished. The mathematical model accounted for the coupled heat transfer by conduction and thermal radiation with the associated phase transition of the bound water in the fabric fibres and diffusion of the water vapour in the clothing layers and air gaps. The skin and muscle were modelled with two equation model which accounted for heat transfer in the tissue and arterial blood. Complex thermal and mass transfer conditions at the internal or external boundaries between the fabric layers, air gaps and skin were assumed. Special attention was paid to modelling of thermal radiation emitted by external heat source, for example, a fire, penetrating through the protective clothing and being absorbed by the skin and muscle.

Temporal and spatial variations of temperature in the protective garment, skin and muscle, as well as volume fractions of the water vapour and bound water in the clothing, were calculated for various intensity of incident radiative heat flux. The results of numerical simulation were used to estimate the risk of the first-, second- and third-degree burns.

Because of the small thickness of the considered system in comparison to its lateral dimensions, the presented model was limited to 1D heat and moisture transfer. The convective heat transfer through the clothing was neglected.

The model may be applied for design of the new protective clothing and for assessment of thermal performance of the various types of protective garments. Additionally, the proposed approach may be used in the medicine for estimation of degree of thermal destruction of the tissue during treatment of burns.

The novel advanced thermal model of the multi-layer protective garment, skin and muscle layer was developed. For the first time, non-grey optical properties and various optical phenomena at the internal or external boundaries between the fabric layers, air gaps and skin were accounted for during simulation of thermal interactions between the external heat source (e.g. a fire), protective clothing and human skin.

This paper adds to the scant literature on the tightening of regulations and its impact on the profitability of insider trades by examining the effects of the recent enactment of the Securities Market Amendment Act 2002 in New Zealand. We investigate the abnormal returns around the date of insider transactions both before and after the introduction of this Act. We find that the number of insider transactions decreased just prior to the introduction of the Act; further we observe a marked reduction in the profitability of directors. However, the difference between the pre and post-change returns lacks statistical significance.

This paper seeks to identify empirically the factors underlying the decision to adopt online banking in Poland.

The sample used in this study is based on 3,519 interactive questionnaires completed by Polish internet users. The dichotomous decision of whether to adopt internet banking services was linked, via Binomial Logistic Regression, to numerous explanatory variables.

Generally, the behaviour of Polish internet users and that of consumers in more developed countries exhibit similar traits. One of the dominant relationships that has been observed in our study is the link between the decision to open an online account and the perceived level of security of internet transactions. Experience with the medium of internet and certain demographic variables also proved to be robust predictors of the adoption status. Moreover, this inquiry documents that advertising appears to be efficacious and that online banking interacts with consumption of other products offered by banks. These findings imply that financial institutions can encourage customers to use this cost‐effective distribution channel through carefully‐planned actions.

The results presented in this paper can be of assistance to banks that either operate in Poland or intend to design a pan‐European strategy. Useful insights are also provided with regard to market segmentation, security and strategies fostering the acceptance of online banking.

The analysis is based on a large sample and broadens our understanding of the attitudes towards innovative financial products by considering factors rarely discussed in prior literature.

The findings would help in designing useful and relevant hedging strategies against geopolitical risks (GPRs), which are rampant in the Gulf Cooperation Council (GCC) region.

This study focuses on the regional and global costs of GPRs for businesses in the Gulf region.

The results of the analysis show that the time-varying conditional correlation between the stock returns of the GCC countries and the Saudi Arabian geopolitical risk is consistently negative, suggesting that the Saudi Arabian geopolitical risk hurts the GCC stock markets, thus underscoring the importance of studying regional GPRs.

The contribution of this paper is twofold: First, it uses a newly geopolitical risk index that includes recent geopolitical events not included in the Caldara and Iacoviello (2018) index. In addition to war threats and acts, terrorist threats and acts and nuclear threats, the authors consider global trade tensions (GTTs), Saudi Arabia's geopolitical risk and OPEC news mainly related to OPEC oil production levels. Second, it assesses whether Saudi Arabia, which is the largest economy in the region and the main global oil exporter, is really a risk exporter to the rest of the GCC countries.