Are stress-free membranes really 'tensionless'?

In recent years it has been argued that the tension parameter driving the fluctuations of fluid membranes, differs from the imposed lateral stress, the 'frame tension'. In particular, stress-free membranes were predicted to have a residual fluctuation tension. In the present paper, this argument is reconsidered and shown to be inherently inconsistent -- in the sense that a linearized theory, the Monge model, is used to predict a nonlinear effect. Furthermore, numerical simulations of one-dimensional stiff membranes are presented which clearly demonstrate, first, that the internal 'intrinsic' stress in membranes indeed differs from the frame tension as conjectured, but second, that the fluctuations are nevertheless driven by the frame tension. With this assumption, the predictions of the Monge model agree excellently with the simulation data for stiffness and tension values spanning several orders of magnitude

TAXATION-FEDERAL INCOME TAX-PAYMENTS UNDER WRITTEN AGREEMENT INCIDENT TO DIVORCE

Petitioner and her husband separated in January 1919 after marital difficulties. The following sequence of events transpired in the next four months: the husband employed detectives to follow his wife and discover evidence on which a divorce action could be predicated; petitioner instituted proceedings for legal separation; a separation agreement was executed under which the husband was to give petitioner an initial payment of $200,000 and subsequent annual payments of$30,000 for her life; the husband began a suit for divorce to which petitioner counterclaimed for a divorce; a divorce was decreed in favor of petitioner. Petitioner did not ask for alimony, relying instead on the separation agreement which provided that it would be unaffected by a subsequent divorce. Petitioner failed to report as income the $30,000 received in 1942 and 1943 and a deficiency for those years was determined by the Commissioner. The Tax Court held these sums to be taxable income to the petitioner. On appeal, held, affirmed. The conduct of the parties and the sequence of events demonstrated that the separation agreement was made in contemplation of divorce and payments made thereunder were incident to the divorce within the meaning of I. R. C., § 22(k). Izrastzoff v. Commissioner, (2d Cir. 1952) 193 F. (2d) 625

Microscopic theory for interface fluctuations in binary liquid mixtures

Thermally excited capillary waves at fluid interfaces in binary liquid mixtures exhibit simultaneously both density and composition fluctuations. Based on a density functional theory for inhomogeneous binary liquid mixtures we derive an effective wavelength dependent Hamiltonian for fluid interfaces in these systems beyond the standard capillary-wave model. Explicit expressions are obtained for the surface tension, the bending rigidities, and the coupling constants of compositional capillary waves in terms of the profiles of the two number densities characterizing the mixture. These results lead to predictions for grazing-incidence x-ray scattering experiments at such interfaces.Comment: 23 pages, 11 figure

Local orientations of fluctuating fluid interfaces

Thermal fluctuations cause the local normal vectors of fluid interfaces to deviate from the vertical direction defined by the flat mean interface position. This leads to a nonzero mean value of the corresponding polar tilt angle which renders a characterization of the thermal state of an interface. Based on the concept of an effective interface Hamiltonian we determine the variances of the local interface position and of its lateral derivatives. This leads to the probability distribution functions for the metric of the interface and for the tilt angle which allows us to calculate its mean value and its mean square deviation. We compare the temperature dependences of these quantities as predicted by the simple capillary wave model, by an improved phenomenological model, and by the microscopic effective interface Hamiltonian derived from density functional theory. The mean tilt angle discriminates clearly between these theoretical approaches and emphasizes the importance of the variation of the surface tension at small wave lengths. Also the tilt angle two-point correlation function is determined which renders an additional structural characterization of interfacial fluctuations. Various experimental accesses to measure the local orientational fluctuations are discussed.Comment: 29 pages, 12 figure

Wall-liquid and wall-crystal interfacial free energies via thermodynamic integration: A molecular dynamics simulation study

A method is proposed to compute the interfacial free energy of a Lennard-Jones system in contact with a structured wall by molecular dynamics simulation. Both the bulk liquid and bulk face-centered-cubic crystal phase along the (111) orientation are considered. Our approach is based on a thermodynamic integration scheme where first the bulk Lennard-Jones system is reversibly transformed to a state where it interacts with a structureless flat wall. In a second step, the flat structureless wall is reversibly transformed into an atomistic wall with crystalline structure. The dependence of the interfacial free energy on various parameters such as the wall potential, the density and orientation of the wall is investigated. The conditions are indicated under which a Lennard-Jones crystal partially wets a flat wall.Comment: 15 pages, 11 figure

Procurement innovation: perspectives from Chinese international construction companies

The international construction business is witnessing a trend that companies deliver projects through the adoption of innovative procurement systems (e.g. Building Operate Transfer, Public Private Partnership). By devising innovative procurement systems, it is possible to realise construction projects that are difficult for traditional procurement methods, to develop competitive advantages for companies, and ultimately, to deliver value to the society. Notably, Chinese companies are making impressive inroads into the international construction market through enhancing their competitiveness. However, little we know about how Chinese international construction companies (CICCs) perceive procurement innovation and how it relates to their recent success. This research aims to capture their perspectives towards procurement innovation by interviewing nine key decision-makers of CICCs and experts in this area. It is found that CICCs are gradually adopting procurement innovation as a competitive strategy. Unlike the traditional life-or-death competition, competing through procurement innovation can make more projects possible; the emergence of CICCs, in particular their strengths, can be encouraged to deliver more projects and value in the international construction market. This research not only provides CICCs with insights into the procurement innovations in the construction sector, but also enables other companies to know CICCs with which they might compete or collaborate in the near future.published_or_final_versio

Description of the fluctuating colloid-polymer interface

To describe the full spectrum of surface fluctuations of the interface between phase-separated colloid-polymer mixtures from low scattering vector q (classical capillary wave theory) to high q (bulk-like fluctuations), one must take account of the interface's bending rigidity. We find that the bending rigidity is negative and that on approach to the critical point it vanishes proportionally to the interfacial tension. Both features are in agreement with Monte Carlo simulations.Comment: 5 pages, 3 figures, 1 table. Accepted for publication in Phys. Rev. Let

Sharpening Competitive Edge through Procurement Innovation: Perspectives from Chinese International Construction Companies

The international construction business is witnessing a trend towards the delivery of projects through the adoption of innovative procurement systems, which allow companies to gain competitive advantages and to potentially deliver enhanced value to society. Notably, Chinese companies are making steady inroads into the international construction market by enhancing competitiveness. However, we know little about the extent to which Chinese international construction companies (CICCs) perceive procurement innovation and how this factor may relate to their recent success. This research aims to fill the void based on interviews with nine CICC key decision‐makers and experts in this area, and the capturing of their perspectives. It is found that CICCs are gradually adopting procurement innovation as a competitive strategy. Although procurement innovation is conducive to competitive advantage in the long run, CICCs have to pay the cost of entering the new market. Thus a “wait‐and‐see” attitude exists in respect of a long term vision. Unlike the traditional win‐lose competitive bidding system, competing through procurement innovation can lead to larger, more suitable market presence. By succinctly describing the CICC story in the international market this research not only provides CICCs themselves with insights into current procurement innovations existing within the construction sector, but also enables other companies to understand the nature of CICCs with which they might compete or collaborate in the near future.postprin

Isotropic-nematic interfacial tension of hard and soft rods: application of advanced grand canonical biased sampling techniques

Coexistence between the isotropic and the nematic phase in suspensions of rods is studied using grand canonical Monte Carlo simulations with a bias on the nematic order parameter. The biasing scheme makes it possible to estimate the interfacial tension gamma in systems of hard and soft rods. For hard rods with L/D=15, we obtain gamma ~ 1.4 kB T/L^2, with L the rod length, D the rod diameter, T the temperature, and kB the Boltzmann constant. This estimate is in good agreement with theoretical predictions, and the order of magnitude is consistent with experiments.Comment: 10 pages, 10 figure

Mesoscopic analysis of Gibbs' criterion for sessile nanodroplets on trapezoidal substrates

By taking into account precursor films accompanying nanodroplets on trapezoidal substrates we show that on a mesoscopic level of description one does not observe the phenomenon of liquid-gas-substrate contact line pinning at substrate edges. This phenomenon is present in a macroscopic description and leads to non-unique contact angles which can take values within a range determined by the so-called Gibbs' criterion. Upon increasing the volume of the nanodroplet the apparent contact angle evaluated within the mesoscopic approach changes continuously between two limiting values fulfilling Gibbs' criterion while the contact line moves smoothly across the edge of the trapezoidal substrate. The spatial extent of the range of positions of the contact line, corresponding to the variations of the contact angle between the values given by Gibbs' criterion, is of the order of ten fluid particle diameters.Comment: 23 pages, 27 figure