Evaluation of the effectiveness of methods of compaction of sandy soil using physical modeling in the laboratory

Surface compacting of soils is one of the measures applied in the practice of construction for the improvement of deformation and strength indicators of soil characteristics. Compacting is used both in creation of artificial bases in the shape of sand blankets and in quality enhancement of sand matresses for constructions as an underlying and levelling layer within road surface. For creation of surface compacting at a site various methods dependent on machines and mechanisms being used are applied: tamping, rolling, vibrocompaction. The research has been executed for evaluation of the efficiency of the indicated means of compacting. The set task was solved in laboratory conditions on physical models in a laboratory tray. In the course of the research the special laboratory tray was made, sandy soil model was chosen, with the help of additional equipment and developed original methodology a modelling of three methods of surface compacting was done, experiments on compacting of physical models with different soil dampness were executed, quantitative and qualitative assessments of surface compacting of sandy soil were given. On the bases of the conducted experiments the most efficient means of surface compacting of sandy soil was found. Recommendations for builders were given

Родиноведение : для первых двух лет обучения

Digiteeritud Euroopa Regionaalarengu Fondi rahastusel, projekti "Eesti teadus- ja õppekirjandus" (2014-2020.12.03.21-0848) raames.https://www.ester.ee/record=b1681657*es

AGE DISCRIMINATION IN THE LABOUR MARKET: A QUANTITATIVE ANALYSIS

This dissertation is dedicated to studying age discrimination in the labour market. This topic has been widely studied in USA and some European countries due to the issue of society ageing and consequential retirement age increases. While Italy faces the same problems, the topic of age discrimination against older workers has not yet received here considerable attention. Our aim was to run a pilot study that would help determine whether age discrimination against older workers could be considered an issue of concern, and if possible, touch upon its roots and motivations for discriminatory actions. In the first chapter, we discuss the concept of discrimination, methods used to study it, state-of-art and theories behind age discrimination in the labour market specifically. We infer that current methods of research, that have not changed a lot since this topic has first received scientific attention, often fail to disentangle actual discrimination from inequality caused by other factors. The second chapter is dedicated to studying the anti-discriminatory legislation aimed specifically at age discrimination in the labour market that was introduced in Italy in 2003. We use quasi experimental approach to analyze whether the introduction of legislation had influence on the older (55-59 age group) workers\u2019 employment rates. In the third chapter, we use laboratory experiment to study age discrimination and factors influencing employment situation of older workers compared to younger ones by simulating a hiring situation among the students of University of Brescia. The results of our research prove that certain extent of discrimination against older works does exist in the labour market of Italy. This fact is, firstly, indirectly proven by the results of policy analysis. Anti-discriminatory legislation did have positive impact on employment rate of older workers without influencing younger workers in the same way. Secondly, the experiment results show that the participants tended to significantly prefer younger workers compared to older workers, especially for the job that required more physical than intellectual work and if older workers had the same experience as younger workers. Moreover, older women were more discriminated than older men. We, however, also found that such factors as higher experience and existence of up-to-date training tended to mitigate that effect and make older workers even more competitive than younger workers. We did not find that personal attitudes had impact on hiring decisions but health stereotypes about older workers being less healthy than younger workers did have negative impact on hiring decisions. Additionally, we found out that culture-related factors were important in decisions-making. However, their nature and mechanism remain to be studied in a more detailed way. We conclude by pointing out the importance of further research in this field and the necessity to study cultural and unconscious motives (with additional help of cognitive methods) as the reason behind discriminatory actions

Русская грамматика по новой орфографии с упражнениями

Digiteeritud Euroopa Regionaalarengu Fondi rahastusel, projekti "Eesti teadus- ja õppekirjandus" (2014-2020.12.03.21-0848) raames.https://www.ester.ee/record=b1681661*es

Association behavior of binary polymer mixtures under elongational flow

The influence of elongational flow on the association behavior of binary mixtures of functionalized polymers capable of forming single reversible orientationally dependent bonds, such as hydrogen bonds, is studied analytically. Applying a mean-field approach with an external potential representing the effect of the elongational flow, the orientation distribution functions for the dumbbell model and the freely jointed model of a polymer chain were obtained. Two opposite factors determine the association of “linear” diblock copolymerlike chains: the unfavorable extra stretching under flow of associated polymer chains and the favorable orientation of the chains (segments) along the flow direction. The former dominates and the fraction of associated “linear” chains decreases with increasing flow rate. For mixtures of polymers which are capable of forming associated T-chains, the association also decreases, however, more slowly, and this time due to unfavorable orientational effects. If the formation of associated linear and T-polymers as well as complex linear/T-polymers is possible, a strong preference for the formation of associated T-chains is found. At high flow rates any type of association becomes unfavorable

Influence of the role and status of a preschool child on the keeping a positive microclimate inside the family

The article deals with the problem of the influence of the role and status of a child on the keeping a positive microclimate inside the family and positive relationships between parents and children. Preschool age is like no other characterized by the strongest dependence on adults, and this stage of personality development is mainly determined by the child’s relationships with adults. Even adults themselves sometimes do not understand how their personal qualities become the property of children, in what way, according to the specifics of childhood, they are interpreted, and what significance they acquire for the child. In connection with the special educational role of the family, the issue of how to maximize the positive interaction between family members, minimizing the negative impact of adult family members on children, is of particular importance. The article is devoted to this issue. The aim of the study is to identify the influence of the role status of a preschool child on maintaining a positive microclimate in the family. The methodology of our study was based on the application of a set of theoretical and practical methods. As a result of the study, we concluded that parents, in order to maintain a positive microclimate in the family, must take into account the following features of a preschool child: a) a child can arbitrarily control its behavior, as well as processes of attention and remembering, emotional reactions; b) in any type of activity, a child can go beyond the immediate situation, realize the time perspective, at the same time keep in consciousness a chain of interrelated events or different states of a substance or a process; c) the leading value in the psychological development of a preschool child is imagination. In order to maintain a positive microclimate in the family, it is necessary to accept the child as he is, with all his personality characteristics. The main role of the child in such a family is the role of her beloved member

Investigations on the micellization of amphiphilic dendritic copolymers: from unimers to micelles

Since the micellization kinetics is influenced by polymer structure, the spherical three-dimensional topology of amphiphilic dendritic copolymers (ADPs) which hinders the phase separation during micellization is assumed to make the micellization kinetics different. In the literatures, most of the attention has been paid to the morphology transition or the morphology at equilibrium and the micellization kinetics of ADPs is rarely reported. In this study, the micellization processes of amphiphilic dendritic copolymers from unimers to the final equilibrium micelles were monitored by laser light scattering. Based on the closed association mechanism, the thermodynamics of micellization was analysed. The negative thermodynamic quantities indicate that the micellization of ADPs is driven by enthalpy. Based on the change of scattering intensity and hydrodynamic radius (Rh) with time, the detailed micellization kinetics was analysed, which contains two steps. By controlling the temperature and type of solvent, a system in which the concentration has little influence on Rh is obtained. The relaxation times of the two steps decrease with concentration, indicating that at higher concentration the rate of micellization is quicker. With the increasing mass fraction of the hydrophobic part, the relaxation times decrease and the driving force of micellization increases

SAXS studies of the thermally-induced fusion of diblock copolymer spheres : formation of hybrid nanoparticles of intermediate size and shape

Dilute dispersions of poly(lauryl methacrylate)–poly(benzyl methacrylate) (PLMA–PBzMA) diblock copolymer spheres (a.k.a. micelles) of differing mean particle diameter were mixed and thermally annealed at 150 °C to produce spherical nanoparticles of intermediate size. The two initial dispersions were prepared via reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization of benzyl methacrylate in n-dodecane at 90 °C. Systematic variation of the mean degree of polymerization of the core-forming PBzMA block enabled control over the mean particle diameter: small-angle X-ray scattering (SAXS) analysis indicated that PLMA39–PBzMA97 and PLMA39–PBzMA294 formed well-defined, non-interacting spheres at 25 °C with core diameters of 21 ± 2 nm and 48 ± 5 nm, respectively. When heated separately, both types of nanoparticles regained their original dimensions during a 25–150–25 °C thermal cycle. However, the cores of the smaller nanoparticles became appreciably solvated when annealed at 150 °C, whereas the larger nanoparticles remained virtually non-solvated at this temperature. Moreover, heating caused a significant reduction in mean aggregation number for the PLMA39–PBzMA97 nanoparticles, suggesting their partial dissociation at 150 °C. Binary mixtures of PLMA39–PBzMA97 and PLMA39–PBzMA294 nanoparticles were then studied over a wide range of compositions. For example, annealing a 1.0% w/w equivolume binary mixture led to the formation of a single population of spheres of intermediate mean diameter (36 ± 4 nm). Thus we hypothesize that the individual PLMA39–PBzMA97 chains interact with the larger PLMA39–PBzMA294 nanoparticles to form the hybrid nanoparticles. Time-resolved SAXS studies confirm that the evolution in copolymer morphology occurs on relatively short time scales (within 20 min at 150 °C) and involves weakly anisotropic intermediate species. Moreover, weakly anisotropic nanoparticles can be obtained as a final copolymer morphology over a restricted range of compositions (e.g. for PLMA39–PBzMA97 volume fractions of 0.20–0.35) when heating dilute dispersions of such binary nanoparticle mixtures up to 150 °C. A mechanism involving both chain expulsion/insertion and micelle fusion/fission is proposed to account for these unexpected observations

On the Adsorption of Two-State Polymers

Monte Carlo(MC) simulations produce evidence that annealed copolymers incorporating two interconverting monomers, P and H, adsorb as homopolymers with an effective adsorption energy per monomer, $\epsilon_{eff}$, that depends on the PH equilibrium constants in the bulk and at the surface. The cross-over exponent, $\Phi,$ is unmodified. The MC results on the overall PH ratio, the PH ratio at the surface and in the bulk as well as the number of adsorbed monomers are in quantitative agreement with this hypothesis and the theoretically derived $\epsilon_{eff}$. The evidence suggests that the form of surface potential does not affect $\Phi$ but does influence the PH equilibrium.Comment: 22 pages, 10 figure