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To the Editor. DEAR SIR, In the June issue of AIRCRAFT ENGINEERING, Mr V. D. Naylor rightly asserts that, according to one‐dimensional theory, the velocity at the throat of a Laval nozzle is the local sonic velocity, whether friction is present or not. However his proof rests on an expansion law pvn=constant, when n≠y, and the throat velocity which he obtains differs according to the value of n. Both the assumption and the conclusion are false. The confusion which has existed on this point is, therefore, deepened.

This study aims to focus on the perception of leader‐member exchange (LMX). It is assumed that the perceived quality of the relationship is not only related to the actual quality of the relationship, but also to followers' expectancies and preferences. However, little is known about person characteristics that are related to LMX perceptions. This study seeks to examine how far followers' leadership‐related characteristics (romance of leadership, idealised supervisor, need for leadership and dependence) are related to the perception of LMX.

A sample of 588 Dutch employees from different professions filled in questionnaires on romance of leadership, idealised supervisor, need for leadership and dependence and their perception of LMX.

Results indicate a positive relationship between need for leadership/dependence and the perception of LMX, thought not for romance of leadership/idealised supervisor and the perception of LMX. An interaction was found between idealised supervisor and dependence on the perception of LMX.

The study only focuses on four antecedents, although many others could have an effect on the perception of LMX. The study comprised a one‐dimensional assessment of LMX. For future research, a multi‐dimensional assessment is recommended.

The results of this study imply that organisations need to address the expectations that followers have towards their leaders in order to avoid disappointments.

This paper focuses on the perception of LMX and how follower characteristics are related to the perception of LMX. It extends prior research on the perception of leadership into LMX research. Similar to effect on the perception of leadership behaviour, effects on the perception of LMX are important to take into account when LMX is assessed through follower ratings in order to avoid making incorrect conclusions.

This study explores how human actions affect existing supply chain management (SCM) practice.

Using a narrative approach, this qualitative in-depth case study looks at micro-human activities in SCM practices in the Russian Arctic. Data from personal observations, 13 semi-structured interviews and archival materials are interpreted through the concepts of institutional work and institutional logics.

The study reveals how human actions and institutions affect each other and change existing SCM practice constrained by institutional order and logics. The findings identify two forms of institutional work, initiated by the presence of conflicts of interest between practitioners engaged in different organisational routines, that become an essential driver for logic change. Social action, often invisible in practice, is indicated by finding compromises and informal arrangements that shape interactive activity among practitioners. The findings show that changes enacted by human actions in SCM practice have envisioned new forms of collaboration among supply chain members, thereby making supply chains in the Russian Arctic more integrated than before.

This study involves a limited number of supply chain practitioners, making it imperative to study larger samples, specifically from various empirical contexts.

This study suggests an alternative approach focusing on SCM practice as consistent patterns of human actions, to reflect on supply chain integration problems. It provides an understanding of how practitioners are influenced by and active in producing institutional change. An issue of practitioners' responsibility and morality regarding the consequences of their decisions when exerting change in existing SCM practice is further emphasised.

THE success of airship transport or any form of airship operation depends to a very large extent upon the efficiency of the ground organisation and equipment. In the past the lack of appreciation of this fundamental fact has been the cause of many of the troubles encountered, and to a large extent the reason for the comparatively slow development of the airship.

A method for non‐linear static and dynamic analysis of flexible systems submerged in water is outlined. The systems considered here include cable and beam elements, as well as buoys and clump weights. Contact and lift‐off between members and the sea floor is also accounted for. The formulation used allows for very large deformations and material non‐linearities. Hydrostatic buoyancy and hydrodynamic drag forces are considered throughout the analyses. These capabilities have been implemented in the general purpose non‐linear finite element program FENRIS. Aspects concerning efficient solution of the non‐linear static and dynamic equations are discussed. In particular, an efficient start‐up procedure for analysis of highly flexible systems is described. The paper shows applications involving static and dynamic analysis of a floating structure kept in place by six mooring lines and a flexible riser system.

Recent years have witnessed the increasingly fierce competition amongst smartphone brands. Hence, smartphone firms urge to prevent current consumers from switching to maintain market position. Based on the push–pull–mooring (PPM) framework, this study aims to explore the drivers of users' intentions to switch from their current smartphone brands.

Based on previous literature and the characteristics of the smartphone purchase, this study identified one pushing, two pulling and five mooring factors. Online questionnaires were collected to test hypotheses using the structural equation modelling approach. An additional netnography study provides further support to the hypotheses.

Results show that regret is a push factor that enhances consumers' switching intentions. Moreover, two pull factors, subjective norms and alternative attractiveness positively influence consumers' switching intentions. Finally, switching costs, emotional commitment and brand community engagement are mooring factors that negatively affect brand-switching intention, whereas consumers' variety seeking has a positive effect.

This study enriches the brand switching literature and offers significant implications for customer retention.

This chapter focuses on the impact of generational differences between younger (Millennial) and older generations of frontline miners on team performance as one of the factors that compelled the mining teams to make a plan (planisa) at the rock-face down the mine. In this context, making a plan is a work strategy the mining teams adopted to offset the adverse impact of intergenerational conflict on their team performance and on their prospects of earning the production bonus. The chapter examines intergenerational conflict within the mining teams as a work and organisational phenomenon rather than simply from a birth cohort perspective. It locates the clash of older and younger generations of miners and their generational identities in the historical, national and social contexts shaping the employment relationship, managerial strategies, work practices and production culture of the apartheid and post-apartheid deep-level mining. This shows the impact that the society has in shaping the differences across generations. The chapter highlights work group dynamics that generated conflict between the older and younger generations of frontline mineworkers. The chapter argues that at the heart of the intergenerational conflict was their orientation towards work and management decisions.

THE general shape of the hull is one of lower fineness ratio (5.5) than has been employed in previous rigid airships and it has no parallel portion. It approximates closely to a shape (known as U 721) evolved by the National Physical Laboratory during the war and found to have a remarkably low drag coefficient—little more than 2 per cent. of the resistance of a circular plate of the same diameter as the maximum diameter of the form. The drag coefficient of the bare hull of R 33 (which is typical of the best of the older shapes) in the wind tunnel is 0.0115, that of R 101 is 0.00725 with polygonal cross‐section of 30 sides.

To examine associations by gender between cancer history and major health insurance transitions (gains and losses), and relationships between insurance transitions and access to care.

Longitudinal 2008–2013 Medical Expenditure Panel Survey data were pooled yielding 2,223 cancer survivors and 50,692 individuals with no cancer history ages 18–63 years upon survey entry, with gender-specific sub-analyses. Access-to-care implications of insurance loss or gain were compared by cancer history and gender.

Initially uninsured cancer survivors were significantly more likely to gain insurance coverage than individuals with no cancer history (RR: 1.25; 95% CI: 1.08–1.44). Females in particular were significantly more likely to gain insurance (unmarried RR: 1.16; 95% CI: 1.06–1.28; married RR: 1.09; 95% CI: 1.02–1.16). Significantly higher rates of difficulty accessing needed medical care and prescription medications were reported by those remaining uninsured, those who lost insurance, and women in general. Remaining uninsured, losing insurance, and male gender were associated with lack of a usual source of care.

Additional outreach to disadvantaged populations is needed to improve access to affordable insurance and medical care. Future longitudinal studies should assess whether major Affordable Care Act (ACA) provisions enacted after the 2008–2013 study period (or those of ACA’s replacement) are addressing these important issues.

Loss of health insurance coverage can reduce health care access resulting in poor health outcomes. Cancer survivors may be particularly at risk of insurance coverage gaps due to the long-term chronic disease trajectory. This study is novel in exploring associations between cancer history by gender and health insurance transitions, both gains and losses, in a national non-elderly adult sample.