231 research outputs found

### Histories and futures of business in a turbulent world

When it comes to events that have marked turning points in the relationship between global governance and business history, I have focused on the role of international crises to understand the forces shaping relations between firms, states, and global governance frameworks. Such an approach stems from the fact that I am primarily an historian of international relations, and much of my research and writing is concentrated on European and global history in the period from about 1880 to 1950. For me, the origins and course of the two world wars and the Cold War have been as important as crises of capitalism, such as the Great Depression

### Lessons of Keynesâs Economic Consequences in a Turbulent Century

Just over a century old, John Maynard Keynesâs The Economic Consequences of the Peace (1919) remains a seminal document of the twentieth century. At the time, the book was a prescient analysis of political events to come. In the decades that followed, this still controversial text became an essential ingredient in the unfolding of history. In this essay, we review the arc of experience since 1919 from the perspective of Keynesâs influence and his changing understanding of economics, politics, and geopolitics. We identify how he, his ideas, and this text became key reference points during times of turbulence as actors sought to manage a range of shocks. Near the end of his life, Keynes would play a central role in planning the world economyâs reconstruction after World War II. We argue that the âglobal orderâ that evolved since then, marked by increasingly polarized societies, leaves the community of nations ill prepared to provide key global public goods or to counter critical collective threats

### Linear relaxation to planar Travelling Waves in Inertial Confinement Fusion

We study linear stability of planar travelling waves for a scalar
reaction-diffusion equation with non-linear anisotropic diffusion. The
mathematical model is derived from the full thermo-hydrodynamical model
describing the process of Inertial Confinement Fusion. We show that solutions
of the Cauchy problem with physically relevant initial data become planar
exponentially fast with rate s(\eps',k)>0, where
\eps'=\frac{T_{min}}{T_{max}}\ll 1 is a small temperature ratio and $k\gg 1$
the transversal wrinkling wavenumber of perturbations. We rigorously recover in
some particular limit (\eps',k)\rightarrow (0,+\infty) a dispersion relation
s(\eps',k)\sim \gamma_0 k^{\alpha} previously computed heuristically and
numerically in some physical models of Inertial Confinement Fusion

### Model Equation for the Dynamics of Wrinkled Shockwaves: Comparison with DNS and Experiments

International audienceA model equation for the dynamics and the geometry of the wrinkled front of shock waves, obtained for strong shocks in the Newtonian limit, is tested by comparison with direct numerical simulations and a shock tube experiment

### A Variational Principle Based Study of KPP Minimal Front Speeds in Random Shears

Variational principle for Kolmogorov-Petrovsky-Piskunov (KPP) minimal front
speeds provides an efficient tool for statistical speed analysis, as well as a
fast and accurate method for speed computation. A variational principle based
analysis is carried out on the ensemble of KPP speeds through spatially
stationary random shear flows inside infinite channel domains. In the regime of
small root mean square (rms) shear amplitude, the enhancement of the ensemble
averaged KPP front speeds is proved to obey the quadratic law under certain
shear moment conditions. Similarly, in the large rms amplitude regime, the
enhancement follows the linear law. In particular, both laws hold for the
Ornstein-Uhlenbeck process in case of two dimensional channels. An asymptotic
ensemble averaged speed formula is derived in the small rms regime and is
explicit in case of the Ornstein-Uhlenbeck process of the shear. Variational
principle based computation agrees with these analytical findings, and allows
further study on the speed enhancement distributions as well as the dependence
of enhancement on the shear covariance. Direct simulations in the small rms
regime suggest quadratic speed enhancement law for non-KPP nonlinearities.Comment: 28 pages, 14 figures update: fixed typos, refined estimates in
section

### Task-specific transfer of perceptual learning across sensory modalities

It is now widely accepted that primary cortical areas of the brain that were once thought to be sensory-specific undergo significant functional reorganisation following sensory deprivation. For instance, loss of vision or audition leads to the brain areas normally associated with these senses being recruited by the remaining sensory modalities [1]. Despite this, little is known about the rules governing crossmodal plasticity in people who experience typical sensory development, or the potential behavioural consequences. Here, we used a novel perceptual learning paradigm to assess whether the benefits associated with training on a task in one sense transfer to another sense. Participants were randomly assigned to a spatial or temporal task that could be performed visually or aurally, which they practiced for five days; before and after training, we measured discrimination thresholds on all four conditions and calculated the extent of transfer between them. Our results show a clear transfer of learning between sensory modalities; however, generalisation was limited to particular conditions. Specifically, learned improvements on the spatial task transferred from the visual domain to the auditory domain, but not vice versa. Conversely, benefits derived from training on the temporal task transferred from the auditory domain to visual domain, but not vice versa. These results suggest a unidirectional transfer of perceptual learning from dominant to non-dominant sensory modalities and place important constraints on models of multisensory processing and plasticity

### Nonsteady condensation and evaporation waves

We study motion of a phase transition front at a constant temperature between
stable and metastable states in fluids with the universal Van der Waals
equation of state (which is valid sufficiently close to the fluid's critical
point). We focus on a case of relatively large metastability and low viscosity,
when it can be shown analytically that no steadily moving phase-transition
front exists. Numerically simulating a system of the one-dimensional
Navier-Stokes and continuity equations, we find that, in this case, the
nonsteady phase-transition front emits acoustic shocks in forward and backward
directions. Through this mechanism, the front drops its velocity and eventually
comes to a halt. The acoustic shock wave may shuttle, bouncing elastically from
the system's edge and strongly inelastically from the phase transition front.
Nonsteady rarefaction shock waves appear in the shuttle process, despite the
fact that the model does not admit steady rarefaction waves propagating between
stationary states. If the viscosity is below a certain threshold, an
instability sets in, driving the system into a turbulent state. This work was
supported by the Japan Society for Promotion of Science.Comment: revtex text file and four eps files with figures. Physical Review
Letters, in pres

### The Thermonuclear Explosion Of Chandrasekhar Mass White Dwarfs

The flame born in the deep interior of a white dwarf that becomes a Type Ia
supernova is subject to several instabilities. We briefly review these
instabilities and the corresponding flame acceleration. We discuss the
conditions necessary for each of the currently proposed explosion mechanisms
and the attendant uncertainties. A grid of critical masses for detonation in
the range $10^7$ - $2 \times 10^9$ g cm$^{-3}$ is calculated and its
sensitivity to composition explored. Prompt detonations are physically
improbable and appear unlikely on observational grounds. Simple deflagrations
require some means of boosting the flame speed beyond what currently exists in
the literature. ``Active turbulent combustion'' and multi-point ignition are
presented as two plausible ways of doing this. A deflagration that moves at the
``Sharp-Wheeler'' speed, $0.1 g_{\rm eff} t$, is calculated in one dimension
and shows that a healthy explosion is possible in a simple deflagration if the
front moves with the speed of the fastest floating bubbles. The relevance of
the transition to the ``distributed burning regime'' is discussed for delayed
detonations. No model emerges without difficulties, but detonation in the
distributed regime is plausible, will produce intermediate mass elements, and
warrants further study.Comment: 28 pages, 4 figures included, uses aaspp4.sty. Submitted to Ap

### Finite size effects near the onset of the oscillatory instability

A system of two complex Ginzburg - Landau equations is considered that applies at the onset of the oscillatory instability in spatial domains whose size is large (but finite) in one direction; the dependent variables are the slowly modulated complex amplitudes of two counterpropagating wavetrains. In order to obtain a well posed problem, four boundary conditions must be imposed at the boundaries. Two of them were already known, and the other two are first derived in this paper. In the generic case when the group velocity is of order unity, the resulting problem has terms that are not of the same order of magnitude. This fact allows us to consider two distinguished limits and to derive two associated (simpler) sub-models, that are briefly discussed. Our results predict quite a rich variety of complex dynamics that is due to both the modulational instability and finite size effects

### An Exploratory Study into the Factors Impeding Ethical Consumption

Although consumers are increasingly engaged with ethical factors when forming opinions about products and making purchase decisions, recent studies have highlighted significant differences between consumersâ intentions to consume ethically, and their actual purchase behaviour. This article contributes to an understanding of this âethical purchasing gapâ through a review of existing literature, and the inductive analysis of focus group discussions. A model is suggested which includes exogenous variables such as moral maturity and age which have been well covered in the literature, together with further impeding factors identified from the focus group discussions. For some consumers, inertia in purchasing behaviour was such that the decision-making process was devoid of ethical considerations. Several manifested their ethical views through post-purchase dissonance and retrospective feelings of guilt. Others displayed a reluctance to consume ethically due to personal constraints, a perceived negative impact on image or quality, or an outright negation of responsibility. Those who expressed a desire to consume ethically often seemed deterred by cynicism, which caused them to question the impact they, as an individual, could achieve. These findings enhance the understanding of ethical consumption decisions and provide a platform for future research in this area

- âŠ