Study Of Growth Processes Research Articles

Accentuated lines in the enamel of primary incisors from skeletal remains: A contribution to the explanation of early childhood mortality in a medieval population from Poland

Physiological disruptions resulting from an impoverished environment during the first years of life are of key importance for the health and biological status of individuals and populations. Studies of growth processes in archaeological populations point to the fact that the main causes of childhood mortality in the past are to be sought among extrinsic factors. Based on this assumption, one would expect random mortality of children, with the deceased individuals representing the entire subadult population. The purpose of this study is to explore whether differences in early childhood survival are reflected in differences in deciduous tooth enamel, which can provide an insight into the development of an individual during prenatal and perinatal ontogeny. Deciduous incisors were taken from 83 individuals aged 2.0-6.5 years from a medieval inhumation cemetery dated AD 1300-1600. Prenatal and postnatal enamel formation time, neonatal line width, and the number of accentuated lines were measured using an optical microscope. The significantly wider neonatal line and the higher frequency of accentuated lines in the enamel of the incisors of children who died at the age of 2-3 years suggest the occurrence of stronger or more frequent stress events in this group. These results indicate that in skeletal populations mortality was not exclusively determined by random external factors. Individuals predisposed by an unfavorable course of prenatal and perinatal growth were more likely to die in early childhood.

Brownian Gibbs property for Airy line ensembles

Consider a collection of N Brownian bridges \(B_{i}:[-N,N] \to \mathbb{R} \), B i (−N)=B i (N)=0, 1≤i≤N, conditioned not to intersect. The edge-scaling limit of this system is obtained by taking a weak limit as N→∞ of the collection of curves scaled so that the point (0,21/2 N) is fixed and space is squeezed, horizontally by a factor of N 2/3 and vertically by N 1/3. If a parabola is added to each of the curves of this scaling limit, an x-translation invariant process sometimes called the multi-line Airy process is obtained. We prove the existence of a version of this process (which we call the Airy line ensemble) in which the curves are almost surely everywhere continuous and non-intersecting. This process naturally arises in the study of growth processes and random matrix ensembles, as do related processes with “wanderers” and “outliers”. We formulate our results to treat these relatives as well.Note that the law of the finite collection of Brownian bridges above has the property—called the Brownian Gibbs property—of being invariant under the following action. Select an index 1≤k≤N and erase B k on a fixed time interval (a,b)⊆(−N,N); then replace this erased curve with a new curve on (a,b) according to the law of a Brownian bridge between the two existing endpoints (a,B k (a)) and (b,B k (b)), conditioned to intersect neither the curve above nor the one below. We show that this property is preserved under the edge-scaling limit and thus establish that the Airy line ensemble has the Brownian Gibbs property.An immediate consequence of the Brownian Gibbs property is a confirmation of the prediction of M. Prähofer and H. Spohn that each line of the Airy line ensemble is locally absolutely continuous with respect to Brownian motion. We also obtain a proof of the long-standing conjecture of K. Johansson that the top line of the Airy line ensemble minus a parabola attains its maximum at a unique point. This establishes the asymptotic law of the transversal fluctuation of last passage percolation with geometric weights. Our probabilistic approach complements the perspective of exactly solvable systems which is often taken in studying the multi-line Airy process, and readily yields several other interesting properties of this process.

Study of growth processes and mechanical properties of nanoscale multilayered C/C films

The growth processes of carbon films deposited using two techniques (sputtering and RF plasma assisted chemical vapor deposition, PACVD), and the effects of stacking these films in a multilayered structure on their mechanical and adhesion properties were studied. The films deposited by the two techniques differed in composition, structure and hardness. They are termed “hard C” and “soft C” according to their synthesis process, sputtering and PACVD respectively. By means of stress measurements and angle-resolved X-ray photoelectron spectroscopy, the growth mechanism of the films was characterized when they were deposited on a silicon substrate and when one kind of carbon film was deposited onto the other kind, in order to simulate a multi-layer film formation. This study evidenced the effect of converting the individual layer surfaces into interfaces when building a multilayer film. On one hand, this conversion appeared to increase the compressive stress of the multilayer films for the lowest periodicity (14nm and 7nm of half-period). On the other hand, a strong correlation between the stress resulting from multilayering and the film elasto-plastic properties was found. A hardening effect, put in evidence by applying a nano-indentation “plasticity index”, was obtained for the most layered films (i.e. with the lowest modulation period) and this effect is discussed in relation with the existing models for multi-layer strengthening. The film adhesion to polyethylene terephtalate (PET) substrates was investigated. A beneficial effect of multi-layering on film adhesion was significant only when the half-width period went down to 14nm and 7nm. The adhesion improvement cannot be related to a reduced internal stress, since the most stressed films were also the most adherent. Instead the compressive stress found in the films with the lowest periodicity is thought to induce a stronger bonding of the soft C layer (polymer-like) to the PET substrate and to the hard C layers, through chain entanglement across the interface.

Study of Growth Processes in Bone and Skin Tissues in Porous Implants Designed for Fixation of External Prosthesis after Amputation of Extremities.

Modeling in vivo (on Wistar rats) was carried out by the method of complete integration of the prosthesis of an amputated extremity with a residuum; in this procedure the prosthesis is fixed to the residuum with a metal pylon one end of which is implanted into the bone of the residuum, while the other end traverses the residuum tissues and skin 5-7 cm above the residuum surface. This procedure includes not only successful implantation in the residuum bone, but also the possibility that the pores in the metal pylon can be filled with skin cells in the area of the pylon which traverses the tissues of the residiuum. The porous titanium pylon was implanted into the bone of experimental animals with amputated extremities. Penetration of bone and skin cells into the pores of the studied material was demonstrated, which provides tighter fixation in the bone and shows promise for the development of a natural cutaneous barrier to infection.

Clubs de convergence et effets de débordements géographiques : une analyse spatiale sur données régionales européennes, 1980-1995

Our article offers an econometric model of spatial interactions for the empirical analysis of growth in European regions over the period 1980-1995. The model detects spatial spillover effects and makes it possible to take account of the European economy’s strong polarization. More specifically, by factoring in both spatial autocorrelation and spatial heterogeneity, we characterize the economic polarization pattern in European regions, identify convergence clubs, and model them as spatial regimes. We estimate a two-regime model with spatially autocorrelated errors and show that the convergence process differs between the two regimes. We find a strongly significant spatial spillover effect : the average growth rate of per capita GDP of a given region is positively affected by the average growth rate of neighboring regions. The spatial environment therefore plays a prominent role in the study of growth processes.

High resolution and analytical transmission electron microscopy study of growth processes in a YBCO thin film

High resolution and analytical transmission electron microscopy study of growth processes in a YBCO thin film

Studies of growth processes from the vapour phase of silicon carbide epitaxial layers: III. Thermodynamics of the high temperature processes in the system SiC-N 2 at constant volume

The thermodynamic analysis of high temperature processes in the SiC-N 2 system has been carried out at different initial pressures of nitrogen in the closed system 4, 200, 400, 600, 760, 1140 and 1520 Torr in the temperature interval (1500–3000) K. On the basis of thermodynamic analysis data it has been established that the stoichiometric relationship of silicon and carbon containing components in the vapour phase greatly depends on nitrogen pressure and temperature and this dependence is to be taken into account when analysing the phenomena of luminescence and polytypism in the course of growing silicon carbide monocrystals and epitaxial layers from the vapour phase. The “extent of development” of silicon carbide/nitrogen interaction reactions has been estimated and it has been shown that to certain temperatures (which depend on initial nitrogen pressure i P N 2 and shift toward higher temperatures under the increase of i P N 2 ) it is most likely the reaction, accompanied by the formation of liquid silicon and gaseous cyanogen.

Studies of growth processes in silicon carbide epitaxial layers from the vapour phase: II. Thermodynamic analysis of equilibrium in the SiC-H 2 system at constant hydrogen pressure

A thermodynamic analysis of the equilibrium in the SiC-H 2 system has been carried out at various constant pressures (1, 5 × 10 -1, and 10 -2 atm) over the 1500–3000 K temperature range. On the basis of thermodynamic analysis data it has been established that the stoichiometric relationship of the silicon- and carbon-containing components in the vapour phase greatly depends on the hydrogen temperature and pressure. This dependence is to be taken into account when analysing the processes of diffusion mass-transfer and heterogeneous interactions in the course of growing silicon carbide epitaxial layers. “The extent of development” of silicon carbide-hydrogen interactions has been estimated, and it has been found that for all H 2 pressures studied in the 1850–2350 K temperature range, the reaction accompanied by the formation of gaseous silicon and C 2H 2 is the most likely.

Review of Child Development: A Study of Growth Processes.

Review of Child Development: A Study of Growth Processes.