On Orbits for a Particular Case of Axial Symmetry

A particular case of steady state and axial symmetry - the potentialformula proposed by Miyamoto and Nagai - is studied. A number of orbits of abound test particle is determined numerically, with both, the potentialparameters and initial conditions, varied. Unlike special cases, such asnearly circular and nearly planar orbits, in the case of "truly spatial orbits" the time dependence of the coordinates becomes very complicated and amathematical treatment including any known periodic functions is hardlypossible. Bearing in mind that orbits studied in the present paper aredetermined by three elements, the authors propose the mean values over time ofthe squares of velocity components to characterize them

LR and L+R Systems

We consider coupled nonholonomic LR systems on the product of Lie groups. As examples, we study $n$-dimensional variants of the spherical support system and the rubber Chaplygin sphere. For a special choice of the inertia operator, it is proved that the rubber Chaplygin sphere, after reduction and a time reparametrization becomes an integrable Hamiltonian system on the $(n-1)$--dimensional sphere. Also, we showed that an arbitrary L+R system introduced by Fedorov can be seen as a reduced system of an appropriate coupled LR system.Comment: 18 pages, 1 figur

Razvoj i ocjena modela za predikciju temperature površine kolničke konstrukcije

This paper examines the existing models for predicting pavement temperatures and formulates a new one using a regression equation to predict the minimum and maximum pavement surface temperatures depending on the air temperature. Also, the paper presents a model for pavement temperature prediction according to the Superpave methodology and conducts the validation of the model for measured temperatures.U članku su predstavljeni postojeći modeli za predikciju temperature kolnika i formuliran je novi model pomoću regresione jednadžbe kojom se predviđaju minimalne i maksimalne temperature površine kolnika u ovisnosti od temperature zraka. Također je predstavljen i model za predikciju temperature prema Superpave metodologiji i izvedeno je vrednovanje modela za izmjerene temperature

A simple and efficient DNA isolation method for Ornithogalum L. species (Hyacinthaceae, Asparagales)

We report an efficient, simple and cost-effective protocol for the isolation of genomic DNA from Ornithogalum species. Our modification of the standard CTAB protocol includes two polyphenol adsorbents (insoluble PVPP and activated charcoal), high NaCl concentrations (4 M) for removing polysaccharides, and addition of phenol to remove proteins and other contaminants. DNA yield obtained with our protocol was 223 and 312 μg DNA g-1 of dry leaf tissue. The absorbance ratio 260/280 nm was 1.879 (O. refractum) and 1.753 (O. sibthorpii), and the absorbance ratio 260/230 nm was 1.779 (O. refractum) and 1.545 (O. sibthorpii), revealing lack of contamination. PCR amplifications of one nuclear marker (26S rDNA) indicated that this DNA isolation protocol may be used for Ornithogalum plants containing many interfering compounds for further analyses in population genetics and phylogeographic studies

Absorbing-state phase transitions with extremal dynamics

Extremal dynamics represents a path to self-organized criticality in which the order parameter is tuned to a value of zero. The order parameter is associated with a phase transition to an absorbing state. Given a process that exhibits a phase transition to an absorbing state, we define an ``extremal absorbing" process, providing the link to the associated extremal (nonabsorbing) process. Stationary properties of the latter correspond to those at the absorbing-state phase transition in the former. Studying the absorbing version of an extremal dynamics model allows to determine certain critical exponents that are not otherwise accessible. In the case of the Bak-Sneppen (BS) model, the absorbing version is closely related to the "$f$-avalanche" introduced by Paczuski, Maslov and Bak [Phys. Rev. E {\bf 53}, 414 (1996)], or, in spreading simulations to the "BS branching process" also studied by these authors. The corresponding nonextremal process belongs to the directed percolation universality class. We revisit the absorbing BS model, obtaining refined estimates for the threshold and critical exponents in one dimension. We also study an extremal version of the usual contact process, using mean-field theory and simulation. The extremal condition slows the spread of activity and modifies the critical behavior radically, defining an ``extremal directed percolation" universality class of absorbing-state phase transitions. Asymmetric updating is a relevant perturbation for this class, even though it is irrelevant for the corresponding nonextremal class.Comment: 24 pages, 11 figure

Coefficient stability of operator–difference schemes

A priori estimates expressing continuous dependence of the solution of a first order evolutionary equation in Hubert space on initial condition, right hand side and operator perturbations are obtained in time–integral norms. Analogous results hold for corresponding finite difference schemes. Operatorinių-diferencialinių schemų koeficientis stabilumas Santrauka Darbe tiriamas pirmosios eiles nestacionariu diferencialiniu lygčiu, apibrežtu Huberto erdvese, stabilumas pradines salygos, laisvuju nariu ir operatoriaus koeficientu atžvilgiu. Stabilumo iverčiai irodomi integralinese laiko atžvilgiu normose. Analogiški rezultatai gauti ir baigtiniu skirtumu schemoms. Irodyti stipraus stabilumo iverčiai, kai modifikuojami lygties operatorius ir pradine salyga. Teoriniai rezultatai pritaikyti vienmačiam šilumos laidumo uždaviniui ir ji aproksimuojančiai baigtiniu skirtumu schemai. First Published Online: 14 Oct 201

Nutritional habits in children: Research on health-related habits in schoolchildren in the Republic of Serbia in 2017

Introduction. Childhood nutritional habits may have a tremendous influence on long-term health. Nutritional habits developed during childhood may turn into a lifetime habit. Missed meals, skipping breakfast, and increased intake of sweets are related to overweight and obesity. We aimed to research nutritional habits in schoolchildren in Serbia. Method. We used the data from the research "Health-related habits in schoolchildren in Serbia in 2017". We used the standardized international protocol of the World Health Organization for data gathering. We polled 3.933 participants, aged 11, 13, and 15. Results. The habit of having breakfast, on schooldays days, shows statistically significant difference around re-gions, for ages 11 (p = 0,001) and 13 (p = 0,000). At the age of 11 (p = 0,046), the majority of children have breakfast on weekends in Belgrade (92,7%). When fruit consumption is concerned, the regions statistically significantly differ for the age 11 (p = 0,006). The greatest consumption of fruit is found in the region of Vojvodina (37,4%). In Belgrade, 5% of children never eat vegetables. At the age of 15, there is a statistically significant difference (p = 0,046) in vegetable consumption. Most vegetables are consumed in South and East Serbia (25,5%), and Sumadija and West Serbia (27,4%). There is a statistically significant difference (p=0,016), at the age of eleven, in sweets consumption, among regions. There are the least children who never consumed sweets (1,8%) in Vojvodina. Conclusion. Based on analyzed data, we concluded that children aged eleven, thirteen, and fifteen, in the Republic of Serbia, don't eat quite healthy. The results may be useful for the promotion of health-educational programs, which, in turn, may lead to behavioral changes

The estimates of accuracy of difference schemes for the nonlinear heat equation with weak solution

In this paper we study the convergence of explicit and implicit finite difference scheme for the first initial‐boundary value problem for one dimensional quasilinear heat‐conduction equation with “unbounded nonlinearity”. Baigtinių skirtumų schemų, aproksimuojančių silpnuosius netiesinės šilumos lygties sprendinius, tikslumo įverčiai Santrauka Nagrinejami vienmates netiesines šilumos laidumo lygties skaitiniai sprendimo metodai, kai lygtis turi tik silpnaji sprendini. Lygties koeficientai yra stipriai netiesiniai. Ištirtos išreikštine ir neišreikštine baigtiniu skirtumu schemos. Aproksimuojant funkcijas panaudoti Steklovo vidurkinimo operatoriai. Gautieji paklaidu iverčiai yra suderinti su diferencialinio uždavinio sprendinio glodumu. First Published Online: 14 Oct 201