Dewetting of thin films on heterogeneous substrates: Pinning vs. coarsening

We study a model for a thin liquid film dewetting from a periodic heterogeneous substrate (template). The amplitude and periodicity of a striped template heterogeneity necessary to obtain a stable periodic stripe pattern, i.e. pinning, are computed. This requires a stabilization of the longitudinal and transversal modes driving the typical coarsening dynamics during dewetting of a thin film on a homogeneous substrate. If the heterogeneity has a larger spatial period than the critical dewetting mode, weak heterogeneities are sufficient for pinning. A large region of coexistence between coarsening dynamics and pinning is found.Comment: 4 pages, 4 figure

The relation of steady evaporating drops fed by an influx and freely evaporating drops

We discuss a thin film evolution equation for a wetting evaporating liquid on a smooth solid substrate. The model is valid for slowly evaporating small sessile droplets when thermal effects are insignificant, while wettability and capillarity play a major role. The model is first employed to study steady evaporating drops that are fed locally through the substrate. An asymptotic analysis focuses on the precursor film and the transition region towards the bulk drop and a numerical continuation of steady drops determines their fully non-linear profiles. Following this, we study the time evolution of freely evaporating drops without influx for several initial drop shapes. As a result we find that drops initially spread if their initial contact angle is larger than the apparent contact angle of large steady evaporating drops with influx. Otherwise they recede right from the beginning

Bifurcation analysis of the behavior of partially wetting liquids on a rotating cylinder

We discuss the behavior of partially wetting liquids on a rotating cylinder using a model that takes into account the effects of gravity, viscosity, rotation, surface tension and wettability. Such a system can be considered as a prototype for many other systems where the interplay of spatial heterogeneity and a lateral driving force in the proximity of a first- or second-order phase transition results in intricate behavior. So does a partially wetting drop on a rotating cylinder undergo a depinning transition as the rotation speed is increased, whereas for ideally wetting liquids the behavior \bfuwe{only changes quantitatively. We analyze the bifurcations that occur when the rotation speed is increased for several values of the equilibrium contact angle of the partially wetting liquids. This allows us to discuss how the entire bifurcation structure and the flow behavior it encodes changes with changing wettability. We employ various numerical continuation techniques that allow us to track stable/unstable steady and time-periodic film and drop thickness profiles. We support our findings by time-dependent numerical simulations and asymptotic analyses of steady and time-periodic profiles for large rotation numbers

Are We All in the Same Boat? The Role of Perceptual Distance in Organizational Health Interventions

The study investigates how agreement between leaders' and their team's perceptions influence intervention outcomes in a leadership-training intervention aimed at improving organizational learning. Agreement, i.e. perceptual distance was calculated for the organizational learning dimensions at baseline. Changes in the dimensions from pre-intervention to post-intervention were evaluated using polynomial regression analysis with response surface analysis. The general pattern of the results indicated that the organizational learning improved when leaders and their teams agreed on the level of organizational learning prior to the intervention. The improvement was greatest when the leader's and the team's perceptions at baseline were aligned and high rather than aligned and low. The least beneficial scenario was when the leader's perceptions were higher than the team's perceptions. These results give insights into the importance of comparing leaders' and their team's perceptions in intervention research. Polynomial regression analyses with response surface methodology allow three-dimensional examination of relationship between two predictor variables and an outcome. This contributes with knowledge on how combination of predictor variables may affect outcome and allows studies of potential non-linearity relating to the outcome. Future studies could use these methods in process evaluation of interventions

Leading well is a matter of resources : leader vigour and peer support augments the relationship between transformational leadership and burnout

Although studies suggest that transformational leaders play an important role in employee health and well-being, the relationship between transformational leadership and employee burnout remains unclear. One reason may be that moderators may play an important role. Building on conservation of resources theory, we examined if leaders’ perceptions of internal and external resources in terms of vigour and peer support augmented the relationship between transformational leadership and employee burnout in a sample of municipality workers and their leaders in Sweden (N = 217). Multilevel analyses over two time points revealed that both vigour and peer support enhance this relationship, such that when leaders experience high levels of vigour or peer support, the negative relationship between transformational leadership behaviours and employee burnout was strengthened. Our findings suggest that both personal and contextual resources may help leaders to better engage in transformational leadership, which is important in order to protect employees from burning out

Chiral skyrmions in thin magnetic films: new objects for magnetic storage technologies?

Axisymmetric magnetic lines of nanometer sizes (chiral vortices or skyrmions) have been predicted to exist in a large group of noncentrosymmetric crystals more than two decades ago. Recently these magnetic textures have been directly observed in nanolayers of cubic helimagnets and monolayers of magnetic metals. We develop a micromagnetic theory of chiral skyrmions in thin magnetic layers for magnetic materials with intrinsic and induced chirality. Such particle-like and stable micromagnetic objects can exist in broad ranges of applied magnetic fields including zero field. Chiral skyrmions can be used as a new type of highly mobile nanoscale data carriers

No leader is an island : contextual antecedents to line managers’ constructive and destructive leadership during an organizational intervention

Purpose: Line managers can make or break organizational interventions, yet little is known about what makes them turn in either direction. As leadership does not occur in a vacuum it has been suggested that the organizational context plays an important role. Building on the intervention and leadership literature, we examine if span of control and employee readiness for change are related to line managers’ leadership during an organizational intervention. Design: Leadership is studied in terms of intervention-specific constructive, as well as passive and active forms of destructive, leadership behaviors. As a sample, we use employees (N = 172) from 37 groups working at a process industry plant. Multilevel analyses over two time points, with both survey and organizational register data were used to analyze the data. Findings: The results revealed that span of control was negatively related to constructive leadership and positively related to passive destructive leadership during the intervention. Employee readiness for change was positively related to constructive leadership, and negatively related to both passive and active destructive leadership. Practical implications: Our findings suggest that contextual factors need to be assessed and considered if we want line managers to engage in constructive rather than destructive leadership during interventions. Originality/value: The present study is the first to address line managers’ making or breaking of organizational interventions by examining the influence of context on both their destructive and constructive leadership

On the relationship of magnetocrystalline anisotropy and stoichiometry in epitaxial L1(0) CoPt (001) and FePt (001) thin films

Two series of epitaxial CoPt and FePt films, with nominal thicknesses of 42 or 50 nm, were prepared by sputtering onto single-crystal MgO(001) substrates in order to investigate the chemical ordering and the resultant magnetic properties as a function of alloy composition. In the first series, the film composition was kept constant, while the substrate temperature was increased from 144 to 704 degrees C. In the second series the substrate temperature was kept constant at 704 degrees C for CoPt and 620 degrees C for FePt, while the alloy stoichiometry was varied in the nominal range of 40-60-at. % Co(Fe). Film compositions and thicknesses were measured via Rutherford backscattering spectrometry. The lattice and long-range order parameter for the L1(0) phase were obtained for both sets of films using x-ray diffraction. The room-temperature magnetocrystalline anisotropy constants were determined for a subset of the films using torque magnetometry. The order parameter was found to increase with increasing temperature, with ordering occurring more readily in FePt when compared with CoPt. A perpendicular anisotropy developed in CoPt for substrate temperatures above 534 degrees C and in FePt above 321 degrees C. The structure and width of the magnetic domains in CoPt and FePt, as seen by magnetic force microscopy, also demonstrated an increase in magnetic anisotropy with increasing temperature. For the films deposited at the highest temperatures (704 degrees C for CoPt and 620 degrees C for FePt), the order parameter reached a maximum near the equiatomic composition, whereas the magnetocrystalline anisotropy increased as the concentration of Co or Fe was increased from below to slightly above the equiatomic composition. It is concluded that nonstoichiometric L1(0) CoPt and FePt, with a slight excess of Co or Fe, are preferable for applications requiring the highest anisotropies

In the eye of the beholder: how self-other agreements influence leadership training outcomes as perceived by leaders and their followers

Based on Yammarino and Atwater’s self-other agreement typology of leaders, we explored whether leaders’ and followers’ agreement influenced their ratings of leadership behaviors after training where leaders received multi-source feedback to stimulate behavior change. We used a prospective study design including 68 leaders and 237 followers from a Swedish forest industry company. Leaders underwent training to increase their transformational leadership and contingent reward styles and reduce management-by-exception passive and laissez-faire leadership. We found that self-other agreement influences followers and leaders reporting changes in leadership styles. We also found that although some leader types were perceived to improve their leadership behaviors, leaders and followers reported differential patterns in which types of leaders improved the most. Our results have important implications for how feedback should be used to support training to achieve changes in leadership styles