The relative effect of student, family and school-related factors on math achievement by location of the school

This study aims to examine the relative effects of student, family and school-related characteristics on 4th grade students’ math achievement according to location of the school in Turkey. The data of 6435 students studying at 260 primary schools were analyzed using TIMSS-2015 database. The dependent variable of the study was students’ math scores and 19 factors constituting the student, family and school-related characteristics were the independent variables. The location of the school was classified as urban, suburban, medium-size city and village. The data was analyzed via single level multiple linear regression. The results revealed that the entire models explained the largest amount of variance (52%) in the schools located in the villages and the least amount of variance (44%) in those located in the urban area. Although all of the student, family and school-related characteristic sets were found to be significantly related with the achievement, the student-related characteristics explained the largest amount of variance in achievement. Students’ confidence in math contributed almost the highest amount of variance, and the early numeracy tasks, absenteeism in school, parents’ highest education level, parents’ highest occupation level, early numeric activities before school explained small amounts of variance in students’ math achievement in the schools of all locations.

Characteristic sets verses generalised characteristic sets for ordinary differential polynomial sets

The concept of characteristic sets developed initially by Ritt and Wu has turned into a standard tool for the study of sets or systems of polynomial and algebraic differential equations. With the help of constructing characteristic sets, an arbitrary set or system of polynomials or differential polynomials can be triangularised. It means that it can be decomposed into a particular set or system of triangular forms. In this paper, a comparison of Ritt–Wu’s characteristic sets by Wang for the ordinary differential polynomial sets with the generalised characteristic sets of the ordinary differential polynomial sets by the authors has been presented. Keywords: Characteristic set, differential polynomial, pseudo-division, admissible reduction.

Complexity of rule sets in mining incomplete data using characteristic sets and generalized maximal consistent blocks

In this paper, missing attribute values in incomplete data sets have three possible interpretations: lost values, attribute-concept values and ‘do not care’ conditions. For rule induction, we use characteristic sets and generalized maximal consistent blocks. Therefore, we apply six different approaches for data mining. As follows from our previous experiments, where we used an error rate evaluated by ten-fold cross validation as the main criterion of quality, no approach is universally the best. Thus, we decided to compare our six approaches using complexity of rule sets induced from incomplete data sets. We show that the smallest rule sets are induced from incomplete data sets with attribute-concept values, while the most complicated rule sets are induced from data sets with lost values. The choice between interpretations of missing attribute values is more important than the choice between characteristic sets and generalized maximal consistent blocks.

$L^{p}$ Estimates for Joint Quasimodes of Semiclassical Pseudodifferential Operators Whose Characteristic Sets Have $k$th Order Contact

In this paper we develop $L^{p}$ estimates for functions $u$, which are joint quasimodes of semiclassical pseudodifferential operators $p_{1}(x,hD)$ and $p_{2}(x,hD)$ whose characteristic sets meet with $k$th order contact, $k\geq{}1$. As part of the technical development we use Fourier integral operators to adapt a flat wavelet analysis to the curved level sets of $p_{1}(x,\xi )$.

Restoration of agroecosystems in the Republic of Tyva

Until 1995, a special study of the flora and vegetation of Tuva agroecosystems was not carried out. This work is devoted to the research of features of overgrowth of abandoned arable land, species composition of vegetation, productivity, stages of healing and their duration, prospects of their use as forage lands. Purpose. To determine the main trends of fallow ecosystems in the course of succession: changes in the species composition of phytocenoses, a set of dominant species, ecological groups of plants, the structure of plant matter and primary products in different edaphic conditions, but in the same climatic zone. Methods. For the study of each succession, key sites on the initial (control) and successional ecosystems were selected, where changes in the species composition of communities, the composition of dominants, phytomass stocks and its structure were studied. The studies were conducted in the period 1997-2018. Results. In the sharply continental climate of Tuva, the development of agriculture without irrigation has not justified itself. In the 50-60 years of the last century there were periods of mass development of virgin lands. In the early 1990s, the area of land cultivated for cultivation began to decline sharply. It is shown that the fallow succession proceeds naturally and synchronously. Summary. In arid conditions of Tuva, the initial stage of succession (0-4 years) is weeds. The first intermediate stage (4-7 years) is marked on all deposits by the absolute dominance of wheatgrass and the appearance of dominants characteristic of a certain type of steppes. The second intermediate stage (7-11 years) is characterized in that all deposits are dominated by species of the original indigenous steppes. The late stage (11-20 years) is the phase of formation of terminal communities with characteristic sets of species for each steppe, including the dominant ones.