Exploring disparities and similarities in European food consumption patterns

This paper investigates the heterogeneity of food consumption patterns in Europe. The analysis relies on a wide set of indicators, namely the structure of calorie, protein and fat consumption as well as the consumption of main foodstuffs. Clusters based on estimated income elasticity of calorie and protein demand are also reported. Income elasticities of animal products tend to exceed those corresponding to the total calorie demand. The same pattern holds true for the elasticity of demand for proteins. Main dimensions of consumption are identified based on factor analysis and used subsequently for the purpose of clustering countries. The hard core clusters are those that remain stable regardless of the algorithm used in classification or the indicators as a proxy of food consumption patterns. A limited number of hard core clusters of countries emerged. The paper concludes with a discussion of clusters with homogeneous patterns of consumption.food consumption patterns, Europe, factor analysis, cluster analysis, hard-core clusters

Determinants of Food Choice in a Transitional Economy: Insights from the Theory of Reasoned Action

This paper draws upon a consumer survey carried out in Bucharest (Romania) to explore determinants of food choice in a transition economy. An adapted version of the Theory of Reasoned Action was developed. This included attitude toward intention, habit and preference as independent variables. The structural equations modelling carried out in 'Analysis of MOment Structures' AMOS showed a significant positive influence of all variables. Similar to other studies conducted in European Union (EU) countries (Saba, Di Natale, 1998) habit outweighed the other variables. The study emphasises the heterogeneity of consumer beliefs about food. Furthermore it was suggested that there is scope for noneconomic variables in explaining food choices and consumer behaviour in these emerging economies, though the influence of these variables may be still limited relative the economic factors. Further research on special groups is required to quantify the influence of non-economic factors and compare the results estimated in Romania with other countries which are candidates to EU accession.Theory of Reasoned Action, food choice, transition economy, Consumer/Household Economics,

Linking attractive interactions and confinement to the rheological response of suspended particles close to jamming.

We study the response to simple shear start-up of an overdamped, athermal assembly of particles with tuneable attractive interactions. We focus on volume fractions close to the jamming point, where such systems can become disordered elastoplastic solids. By systematically varying the strength of the particle-particle attraction and the volume fraction, we demonstrate how cohesion and confinement individually contribute to the shear modulus and yield strain of the material. The results provide evidence for the influence of binding agents on the rheology of dense, athermal suspensions and describe a set of handles with which the macroscopic properties of such materials can be engineered

Absorbing-State Transitions in Granular Materials Close to Jamming.

We consider a model for driven particulate matter in which absorbing states can be reached both by particle isolation and by particle caging. The model predicts a nonequilibrium phase diagram in which analogs of hydrodynamic and elastic reversibility emerge at low and high volume fractions respectively, partially separated by a diffusive, nonabsorbing region. We thus find a single phase boundary that spans the onset of chaos in sheared suspensions to the onset of yielding in jammed packings. This boundary has the properties of a nonequilibrium second order phase transition, leading us to write a Manna-like mean field description that captures the model predictions. Dependent on contact details, jamming marks either a direct transition between the two absorbing states, or occurs within the diffusive region.ERC, Royal Society, Pembroke Colleg

Scaling Description of Frictionless Dense Suspensions under Inhomogeneous Flow

Predicting the rheology of dense suspensions under inhomogeneous flow is crucial in many industrial and geophysical applications, yet the conventional “μ(J)” framework is limited to homogeneous conditions in which the shear rate and solids fraction are spatially invariant. To address this shortcoming, we use particle-based simulations of frictionless dense suspensions to derive new constitutive laws that unify the rheological response under both homogeneous and inhomogeneous conditions. By defining a new dimensionless number associated with particle velocity fluctuations and combining it with the viscous number, the macroscopic friction, and the solids fraction, we obtain scaling relations that collapse data from homogeneous and inhomogeneous simulations. The relations allow prediction of the steady state velocity, stress, and volume fraction fields using only knowledge of the applied driving force

Scaling description of frictionless dense suspensions under inhomogeneous flow

Predicting the rheology of dense suspensions under inhomogeneous flow is crucial in many industrial and geophysical applications, yet the conventional `$\mu(J)$' framework is limited to homogeneous conditions in which the shear rate and solids fraction are spatially invariant. To address this shortcoming, we use particle-based simulations of frictionless dense suspensions to derive new constitutive laws that unify the rheological response under both homogeneous and inhomogeneous conditions. By defining a new dimensionless number associated with particle velocity fluctuations and combining it with the viscous number, the macroscopic friction and the solids fraction, we obtain scaling relations that collapse data from homogeneous and inhomogeneous simulations. The relations allow prediction of the steady state velocity, stress and volume fraction fields using only knowledge of the applied driving force.Comment: 5 pages; 3 figure

Interpretation of the vibrational spectra of glassy polymers using coarse-grained simulations

The structure and vibrational density of states (VDOS) of polymer glasses are investigated using numerical simulations based on the classical Kremer-Grest bead-spring model. We focus on the roles of chain length and bending stiffness, the latter being set by imposing three-body angular potentials along chain backbones. Upon increasing the chain length and bending stiffness, structural reorganisation leads to volumetric expansion of the material and build-up of internal stresses. The VDOS has two dominant bands: a low frequency one corresponding to inter- and intra-chain non-bonding interactions and a high frequency one corresponding principally to vibrations of bonded beads that constitute skeletal chain backbones. Upon increasing the steepness of the angular potential, vibrational modes associated with chain bending gradually move from the low-frequency to the high-frequency band. This redistribution of modes is reflected in a reduction of the so-called Boson peak upon increasing chain stiffness. Remarkably, the finer structure and the peaks of the high-frequency band, and their variations with stiffness, can, for short chains, be explained using an analytical solution derived for a model triatomic molecule. For longer chains, the qualitative evolution of the VDOS with chain stiffness is similar, although the distinct peaks observed for short chains become increasingly smoothed-out. Our findings can be used to guide a systematic approach to interpretation of Brillouin and Raman scattering spectra of glassy polymers in future work, with applications in polymer processing diagnostics.Comment: To appear in Macromolecule

Parameter-free predictions of the viscoelastic response of glassy polymers from non-affine lattice dynamics

We study the viscoelastic response of amorphous polymers using theory and simulations. By accounting for internal stresses and considering instantaneous normal modes (INMs) within athermal non-affine theory, we make parameter-free predictions of the dynamic viscoelastic moduli obtained in coarse-grained simulations of polymer glasses at non-zero temperatures. The theoretical results show very good correspondence with rheology data collected from molecular dynamics simulations over five orders of magnitude in frequency, with some instabilities that accumulate in the low-frequency part on approach to the glass transition. These results provide evidence that the mechanical glass transition itself is continuous and thus represents a crossover rather than a true phase transition. The relatively sharp drop of the low-frequency storage modulus across the glass transition temperature can be explained mechanistically within the proposed theory: the proliferation of low-eigenfrequency vibrational excitations (boson peak and nearly-zero energy excitations) is directly responsible for the rapid growth of a negative non-affine contribution to the storage modulus.Comment: 10 pages, 7 figure

Shaken and stirred: Random organization reduces viscosity and dissipation in granular suspensions.

The viscosity of suspensions of large (≥10 μm) particles diverges at high solid fractions due to proliferation of frictional particle contacts. Reducing friction, to allow or improve flowability, is usually achieved by tuning the composition, either by changing particle sizes and shapes or by adding lubricating molecules. We present numerical simulations that demonstrate a complementary approach whereby the viscosity divergence is shifted by driven flow tuning, using superimposed shear oscillations in various configurations to facilitate a primary flow. The oscillations drive the suspension toward an out-of-equilibrium, absorbing state phase transition, where frictional particle contacts that dominate the viscosity are reduced in a self-organizing manner. The method can allow otherwise jammed states to flow; even for unjammed states, it can substantially decrease the energy dissipated per unit strain. This creates a practicable route to flow enhancement across a broad range of suspensions where compositional tuning is undesirable or problematic