Anisotropic dynamics of a vicinal surface under the meandering step instability

We investigate the nonlinear evolution of the Bales-Zangwill instability, responsible for the meandering of atomic steps on a growing vicinal surface. We develop an asymptotic method to derive, in the continuous limit, an evolution equation for the two-dimensional step flow. The dynamics of the crystal surface is greatly influenced by the anisotropy inherent to its geometry, and is characterized by the coarsening of undulations along the step direction and by the elastic relaxation in the mean slope direction. We demonstrate, using similarity arguments, that the coalescence of meanders and the step flow follow simple scaling laws, and deduce the exponents of the characteristic length scales and height amplitude. The relevance of these results to experiments is discussed.Comment: 10 pages, 7 figures; submitted to Phys. Rev.

Investigations on nucleophilic layers made with a novel plasma jet technique

In this work a novel plasma jet technique is used for the deposition of nucleophilic films based on (3-aminopropyl)trimethoxysilane at atmospheric pressure. Film deposition was varied with regard to duty cycles and working distance. Spectral ellipsometry and chemical derivatization with 4-(trifluoromethyl)benzaldehyde using ATR- FTIR spectroscopy measurements were used to characterize the films. It was found that the layer thickness and the film composition are mainly influenced by the duty cycle

Comparison of video and direct observation methods for measuring oral behaviour in veal calves

Measuring behaviour, especially oral behaviour, has always been a debated issue: therefore the aim of this paper is to closely examine the study of oral behaviour in calves and the approaching methodology. Behavioural observations were conducted by two media (direct observations by check sheets and indirect observations by videotapes recorded by cam- eras connected to a digital field switcher and a time-lapse video recorder) in order to compare data and assess the reli- ability and validity of the two methods in identifying some oral behavioural patterns in calves. The study was carried out on 54 Polish Friesian calves housed in group pens and in individual crates. The behaviour of the calves was investigated during the fattening period on the 2nd, 7th, 13th, 18th and 23rd week, one hour before and one hour after each of the two meals. Two experienced observers checked the behaviour of the calves, including oral behaviours on structures and buckets and oral stereotypies, by direct observations using a scan sampling every 2 min- utes. The calves' behaviour was also video recorded on the same days in which the direct observations were carried out and analysed by the same two observers. Percentages of time spent on each type of behaviour were calculated and anal- ysed by Chi-square test. Regardless of the housing system, the comparison between direct and indirect observations revealed significant differences in almost every behavioural category. Licking, biting and nibbling structures, nibbling and sucking the bucket, playing with the bucket and the teat, chewing and oral stereotypies were significantly higher in direct observations compared to indirect (P < 0.001), while inactivity was higher in video recorded observations (P < 0.001). In conclusion, regardless of the type of housing, our results revealed an objective difficulty in analysing videotapes with very detailed behavioural categories, like oral behaviours. Although video recording can certainly represent a useful and practical alternative to direct observations in many situations, the video recording system used in this study for investi- gating calves' oral behaviour, in spite of the use of multiple cameras, could not replace direct observations, probably due to the restricted field of view, the low depth of focus, the black and white vision, the lack of audio and the time-lapse feature

Iron deficiency in infancy: is an immigrant more at risk?

QUESTIONS UNDER STUDY: Iron deficiency with or without anaemia is the most common deficiency in the world. Its prevalence is higher in developing countries and in low socioeconomic populations. We aimed at determining and comparing the prevalence of iron deficiency in an immigrant and non-immigrant population. METHODS: Every child scheduled for a routine check-up at 12 months of age was allowed to participate in the study. Haemoglobin, ferritin, anthropometric data, familial and nutritional status were measured. RESULTS: 586 infants were eligible and 463 were included in the study as they had assessment data at 12 months. Children were divided into two groups: immigrants' children and non-immigrants' children. The global prevalence of iron deficiency was 5.7% at 12 months. A significant difference for iron deficiency was noticed between the groups at 12 months (p = 0.01). Among risk factors, immigration (odds ratio 2.91; 95% CI 1.05-8.04) and unemployment (odds ratio 6.08; 95% CI 1.18-31.30) had the higher odds in the multivariable analysis. CONCLUSION: The prevalence of iron deficiency in the immigrant population is higher than in non-immigrants. Immigration and the category of employment are risk factors for iron deficiency, as starting baby cereals before 9 months is a protective factor. Good socioeconomic conditions in Switzerland, the quality of food for pregnant women and young infants may be the explanation. A study up to five years of age is necessary before drawing general conclusions on infancy

Guidelines for the study of subsidence triggered by hydrocarbon production

This study was carried out by the SEADOG Research Center at Politecnico di Torino (Italy). The purpose of this work was to evaluate which complexity degree would be required to reliably approach a subsidence study for different scenarios. The study was based on sensitivity analyses which were performed using a series of 3D synthetic numerical models of which the structural characteristics and geological and mechanical properties were based on available public data of onshore and offshore hydrocarbon fields in Italy. An array of simulations, both one-way and two-way coupled, were carried out to assess the magnitude and extension of subsidence potentially induced by hydrocarbon production. The results allowed the calculation of subsidence indices defined as the rate of compaction propagation (i.e., the ratio between the maximum surface displacement and the maximum reservoir compaction) and as the rate of volume loss (i.e. the ratio between the volume of the subsidence bowl or cone and the volume variation of the reservoir). These indices together with the degree of the underground systems’ heterogeneity led to the definition of the Intact Rock Qualitative Subsidence Index (IRQSI), upon which the needed complexity degree of a subsidence study can be discerned

Is it possible to make a diagnosis of raw, heated and baked egg allergy in children using cut-offs? A systematic review

The diagnosis of IgE-mediated egg allergy lies both on a compatible clinical history and on the results of skin prick tests (SPTs) and IgEs levels. Both tests have good sensitivity but low specificity. For this reason, oral food challenge (OFC) is the ultimate gold standard for the diagnosis. The aim of the present paper is to systematically review the literature in order to identify, analyze and synthesize the predictive value of SPT and specific IgEs both to egg white and main egg allergens and to review the cut-offs suggested in the literature

Hamiltonian Dynamics and the Phase Transition of the XY Model

A Hamiltonian dynamics is defined for the XY model by adding a kinetic energy term. Thermodynamical properties (total energy, magnetization, vorticity) derived from microcanonical simulations of this model are found to be in agreement with canonical Monte-Carlo results in the explored temperature region. The behavior of the magnetization and the energy as functions of the temperature are thoroughly investigated, taking into account finite size effects. By representing the spin field as a superposition of random phased waves, we derive a nonlinear dispersion relation whose solutions allow the computation of thermodynamical quantities, which agree quantitatively with those obtained in numerical experiments, up to temperatures close to the transition. At low temperatures the propagation of phonons is the dominant phenomenon, while above the phase transition the system splits into ordered domains separated by interfaces populated by topological defects. In the high temperature phase, spins rotate, and an analogy with an Ising-like system can be established, leading to a theoretical prediction of the critical temperature $T_{KT}\approx 0.855$.Comment: 10 figures, Revte

Preliminary study on the effect of size of individual stall on the behavioural and immune reactions of dairy calves

Ten Italian Friesian female calves were housed in individual stalls of two different dimensions (0.73 m x 1.21 m vs 1.00 m x 1.50 m) during the Ist month of life in order to evaluate the effect of space on the welfare of dairy calves. Behavioural observations were made on d 2 to 3 (period 1) and on d 28 to 29 (period 2) during daylight using a time-lapse video recording system. At 10, 20, and 30 d, blood samples were taken and analysed with phytohemagglutinin stimulation to determine lymphocyte proliferation. During the second period, the calves in large stall spent more time lying (P&lt;0.05) and grooming (P&lt;0.001), and the calves in small stalls exhibited more time searching for feed (P&lt;0.001). Lymphocyte proliferation was statistically lower in calves housed in smaller stalls (P&lt;0.01). Moreover, lymphocyte proliferation was negatively correlated with time spent searching for feed (P&lt;0.01)