The long-term effects of psychological demands on chronic fatigue.

Aim: Investigate the impact of psychological job demands and resources on chronic fatigue.

Background: Nurse fatigue is a serious problem with negative consequences on patient safety and nurse well-being. Excessive job demands can exacerbate nurse fatigue, which may limit the ability of nurses to engage in professional practice.

Structure and mechanics of aegagropilae fiber network.

Fiber networks encompass a wide range of natural and manmade materials. The threads or filaments from which they are formed span a wide range of length scales: from nanometers, as in biological tissues and bundles of carbon nanotubes, to millimeters, as in paper and insulation materials. The mechanical and thermal behavior of these complex structures depends on both the individual response of the constituent fibers and the density and degree of entanglement of the network.

Work organization on smallholder dairy farms: a process unique to each farm.

The way smallholder farms organize and carry out work impacts their ability to secure their livelihoods and meet growing demand for agricultural products. This study investigates the way dairy family farms in Brazil manage their workforce to achieve their objectives of production and income. Fifteen smallholder farms were surveyed using the QuaeWork method to understand the work organization on each farm.

Effects of dairy husbandry practices and farm types on raw milk quality collected by different categories of dairy processors in the Peruvian Andes.

In developing countries, milk quality is often mismanaged in relation to husbandry practices, collection logistics, and the production of small batches. This paper investigates how the management of milk quality from farm to dairy processor impacts on both chemical and hygienic indicators, in a context characterized by farm scale diversity, the co-existence of formal and informal markets, and high milk demand. It is based on an analysis of the chemical and hygienic quality of milk samples collected over a 12-month period from 20 farms and three dairy processors.

Flexible fiber in a turbulent flow: a macroscopic polymer.

We describe, for the first time, an experiment devoted to the study of the spatial conformation of a flexible fiber in a turbulent flow. We propose a model for the transition from rigid to flexible regimes as the intensity of turbulence is increased or the elastic energy of the fiber is decreased. This transition occurs for a fiber typical length which is observed experimentally and recovered by our analysis.

Supporting strategic thinking of smallholder dairy farmers using a whole farm simulation tool.

This article investigates how a one-to-one support process based on the use of a whole dairy farm simulation tool helps both farmers to reflect on their production strategies and researchers to better understand the farmers' contexts of action and decision. The support process consists of a minimum of four discussion sessions with the farmer: designing the Initial Scenario and formulating a diagnosis, building and simulating the Project Scenario corresponding to the objective targeted by the farmer, building and comparing alternative scenarios proposed both by the farmer and the researcher, and evaluating the process with the farmer. The approach was tested with six smallholder farmers in Brazil.

Involvement of small-scale dairy farms in an industrial supply chain: when production standards meet farm diversity.

In certain contexts, dairy firms are supplied by small-scale family farms. Firms provide a set of technical and economic recommendations meant to help farmers meet their requirements in terms of the quantity and quality of milk collected. This study analyzes how such recommendations may be adopted by studying six farms in Brazil.

Experimental determination of zonal winds driven by tides.

We describe a new phenomenon of zonal wind generation by tidal forcing. Following a recent theoretical and numerical analysis [A. Tilgner, Phys.

Supporting small-scale dairy farmers in increasing milk production: evidence from Morocco.

This study aimed to evaluate the effects of technical support provided to five small-scale cattle farms in the Tadla irrigation scheme (Morocco) on their milk yield. The first stage consisted of assessing the initial management of dairy herds, especially feeding strategies, and their effects on milk output. This diagnosis revealed major gaps between the existing and the potential milk yield, due to insufficient and imbalanced dietary rations.

Effect of cattle management practices on raw milk quality on farms operating in a two-stage dairy chain.

In many developing countries, milk production varies greatly according to farm size, cattle breed, and milking practices. However, production systems often are dominated by smallholder farms. Therefore, relatively small volumes of milk are delivered daily from numerous farms to intermediate cooperatives which supply industrial units.

Experimental analysis of the stratorotational instability in a cylindrical Couette flow.

This study is devoted to the experimental analysis of the stratorotational instability (SRI). This instability affects the classical cylindrical Couette flow when the fluid is stably stratified in the axial direction. In agreement with recent theoretical and numerical analyses, we describe for the first time in detail the destabilization of the stratified flow below the Rayleigh line (i.

Defect turbulence in a spiral wave pattern in the torsional Couette flow.

Our experimental study is devoted to the transition to defect turbulence of a periodic spiral wave pattern occurring in the flow between a rotating and a stationary disk. As the rotation rate Omega of the disk is increased, the radial phase velocity of the waves changes its sign: The waves that propagate first outward on average, then become stationary and finally propagate inward. As they become stationary, the nucleation of topological defects breaks the periodicity of the pattern.

Nonlinear interactions in a rotating disk flow: From a Volterra model to the Ginzburg-Landau equation.

The physical system under consideration is the flow above a rotating disk and its cross-flow instability, which is a typical route to turbulence in three-dimensional boundary layers. Our aim is to study the nonlinear properties of the wavefield through a Volterra series equation. The kernels of the Volterra expansion, which contain relevant physical information about the system, are estimated by fitting two-point measurements via a nonlinear parametric model.

Evaluating the independence of sex and expression in judgments of faces.

Face recognition models suggest independent processing for functionally different types of information, such as identity, expression, sex, and facial speech. Interference between sex and expression information was tested using both a rating study and Garner's selective attention paradigm using speeded sex and expression decisions. When participants were asked to assess the masculinity of male and female angry and surprised faces, they found surprised faces to be more feminine than angry ones (Experiment 1).

Planar isotropy of passive scalar turbulent mixing with a mean perpendicular gradient.

A recently proposed evolution equation [Vaienti et al., Physica D 85, 405 (1994)] for the probability density functions (PDF's) of turbulent passive scalar increments obtained under the assumptions of fully three-dimensional homogeneity and isotropy is submitted to validation using direct numerical simulation (DNS) results of the mixing of a passive scalar with a nonzero mean gradient by a homogeneous and isotropic turbulent velocity field. It is shown that this approach leads to a quantitatively correct balance between the different terms of the equation, in a plane perpendicular to the mean gradient, at small scales and at large Péclet number.

Visualization of the space-time impulse response of the subcritical wake of a cylinder.

The well-known Benard-von Karman cylinder wake is one of the most challenging phenomena of fluid mechanics. As the Reynolds number of the flow around a cylinder passes through a critical value, alternating vortex shedding appears via a Hopf bifurcation. Theoretical studies of the wake have described the appearance of this self-sustained oscillation as the result of a convective to absolute transition resulting in the formation of a global mode.

Stability analysis of plane wave solutions of the discrete ginzburg-landau equation.

The discrete Ginzburg-Landau model for a family of oscillators linearly coupled with their first neighbors is studied. The full linear stability analysis of the nonlinear plane wave solutions is performed by considering both the wave number (k) of the basic states and the wave number (q) of the perturbations as free parameters. In particular, it is shown that nonlinear plane waves can be destabilized not only by long (q-->0) or short (q=pi) wave perturbations, but also by intermediate wave numbers (0 View Article and Find Full Text PDF

Experimental study of the multipolar vortex instability.

The instability of a vortex subjected to a stationary dipolar or tripolar constraint is studied experimentally by using a rotating deformable cylinder on which two or three rollers are applied. As the Reynolds number and the aspect ratio of the cylinder are varied, different modes of instability are observed and their wavelength and frequency are compared to theoretical predictions. Secondary instability and cyclic breakup are also evidenced in the elliptic geometry.