Glass transition in Ultrathin Polymer Films : A Thermal Expansion Study

Glass transition process gets affected in ultrathin films having thickness comparable to the size of the molecules. We observe systematic broadening of glass transition temperature (Tg) as the thickness of the polymer film reduces below the radius of gyration but the change in the average Tg was found to be very small. Existence of reversible negative and positive thermal expansion below and above Tg increased the sensitivity of our thickness measurements performed using energy dispersive x-ray reflectivity. A simple model of Tg variation as a function of depth expected from sliding motion could explain the results. We observe clear glass transition even for 4 nm polystyrene film that was predicted to be absent from ellipsometry measurements of thicker films.Comment: 11 pages, 5 figure

Two-dimensional Induced Ferromagnetism

Magnetic properties of materials confined to nanometer length scales are providing important information regarding low dimensional physics. Using gadolinium based Langmuir-Blodgett films, we demonstrate that two-dimensional ferromagnetic order can be induced by applying magnetic field along the in-plane (perpendicular to growth) direction. Field dependent exchange coupling is evident in the in-plane magnetization data that exhibit absence of hysteresis loop and show reduction in field required to obtain saturation in measured moment with decreasing temperature.Comment: 4 pages, 3 postscript figures, corrected paper forma

Prodsimplicial-Neighborly Polytopes

Simultaneously generalizing both neighborly and neighborly cubical polytopes, we introduce PSN polytopes: their k-skeleton is combinatorially equivalent to that of a product of r simplices. We construct PSN polytopes by three different methods, the most versatile of which is an extension of Sanyal and Ziegler's "projecting deformed products" construction to products of arbitrary simple polytopes. For general r and k, the lowest dimension we achieve is 2k+r+1. Using topological obstructions similar to those introduced by Sanyal to bound the number of vertices of Minkowski sums, we show that this dimension is minimal if we additionally require that the PSN polytope is obtained as a projection of a polytope that is combinatorially equivalent to the product of r simplices, when the dimensions of these simplices are all large compared to k.Comment: 28 pages, 9 figures; minor correction

Green human resource management: a comparative qualitative case study of a United States multinational corporation

This article explores the ways in which a multinational company (MNC) approaches Green Human Resource Management (HRM) in its British, German and Swedish subsidiaries. The authors analyze the similarities and differences in Green HRM approaches in these three European subsidiaries of a US restaurant chain. This enables the comparison of Green HRM practises and behaviors, and considers the factors that influence the subsidiaries in this particular domain. Therefore, this research addresses the current lack of international comparative research in the field of Green HRM. The methodological approach is multi-case study with 50 participants, using semi-structured interviews and focus groups. The results show evidence of pro-active environmental management, reflected through a range of operational and people-centred initiatives across the three European countries. Although there is an overarching commitment to environmental sustainability, the positioning and alignment of the environment and HR function differ amongst the subsidiaries, as does the way in which the subsidiaries choose to engage the workforce in environmental sustainability. The study identified a number of factors which explain the differences in approach including, amongst others, strategic and performance drivers and cultural dimensions, such as relationships with key stakeholders

The ethos of action learning within a virtual Reflective Practice Forum: an account of practice drawing connections between action learning, community of practice and supervision frameworks

As Action Learning has evolved, it has been adapted to promote learning in various contexts. In this account of practice, we share our perspectives as facilitators of the application of action learning principles within Reflective Practice Forums for Mentoring and Coaching Programme Managers. The ethos of action learning was adopted with the forums to enable the programme managers to engage in regular reflections of their current practices and ongoing professional development. In our assessment of the application of action learning principles and processes within the Reflective Practice Forums, we consider the connections between action learning, communities of practice and supervision frameworks to examine and present the ‘ethos’ of Action Learning within the forums

Growth mechanism of Langmuir-Blodgett films

Langmuir-Blodgett (LB) deposition is an astonishingly simple technique to grow well-ordered correlated metal-organic multilayers. To understand this growth mechanism, we have performed X-ray scattering and atomic force microscopic (AFM) studies on cadmium arachidate LB films exhibiting self-affine and logarithmic in-plane correlation at the interfaces. Using linear stochastic theory for interface evolution, it is proposed that a 1D deposition followed by a 2D desorption process is the growth mechanism of LB films. X-ray and AFM measurements confirm the crossover between these two growth regimes

Extraction of density profile for near perfect multilayers

A simple inversion scheme, based on Born approximation, to determine the electron density profile of near perfect multilayers from specular X-ray reflectivity data has been presented. This scheme is useful for semiconductor multilayers and other thin films, which are grown almost according to the designed parameters. We also indicate the possibility of separating out the contribution of interdiffusion and roughness in electron density profiles of interfaces by utilizing information obtained from the analysis of diffuse scattering data. The extracted compositional profile was used to calculate structural details of epitaxial films along the growth direction. Simulated and metal organic vapor phase epitaxy grown InP/InxGa1−xAs/InP quantum-well systems have been used to demonstrate this scheme

Quantum cosmology with a curvature squared action

The correct quantum description for a curvature squared term in the action can be obtained by casting the action in the canonical form with the introduction of a variable which is the negative of the first derivative of the field variable appearing in the action, only after removing the total derivative terms from the action. We present the Wheeler-DeWitt equation and obtain the expression for the probability density and current density from the equation of continuity. Furthermore, in the weak energy limit we obtain the classical Einstein equation. Finally we present a solution of the wave equation.Comment: 8 pages, revte

A variational problem on Stiefel manifolds

In their paper on discrete analogues of some classical systems such as the rigid body and the geodesic flow on an ellipsoid, Moser and Veselov introduced their analysis in the general context of flows on Stiefel manifolds. We consider here a general class of continuous time, quadratic cost, optimal control problems on Stiefel manifolds, which in the extreme dimensions again yield these classical physical geodesic flows. We have already shown that this optimal control setting gives a new symmetric representation of the rigid body flow and in this paper we extend this representation to the geodesic flow on the ellipsoid and the more general Stiefel manifold case. The metric we choose on the Stiefel manifolds is the same as that used in the symmetric representation of the rigid body flow and that used by Moser and Veselov. In the extreme cases of the ellipsoid and the rigid body, the geodesic flows are known to be integrable. We obtain the extremal flows using both variational and optimal control approaches and elucidate the structure of the flows on general Stiefel manifolds.Comment: 30 page