Kondo Insulator description of spin state transition in FeSb2

The thermal expansion and heat capacity of FeSb2 at ambient pressure agrees with a picture of a temperature induced spin state transition within the Fe t_{2g} multiplet. However, high pressure powder diffraction data show no sign of a structural phase transition up to 7GPa. A bulk modulus B=84(3)GPa has been extracted and the temperature dependence of the Gruneisen parameter has been determined. We discuss here the relevance of a Kondo insulator description for this material.Comment: Physical Review B in press (2005

Charge transfer mechanism and Tc(x) dependence in Y0.8(Ca)0.2Ba2Cu3O6+x

We propose a model for charge transfer mechanism in Y0.8(Ca)0.2Ba2Cu3O6+x to count hole doping of CuO2 planes and x dependence of critical transition temperature T_c. It is assumed the total number of doped holes in the planes is sum of holes that are introduced through two separate channels: substitution of Y3+ by Ca2+ and from CuO chains that are longer than a minimal (critical) length l_min needed for charge transfer to take place. The T_c(x) dependence is obtained by combining calculated x dependence of doping, p(x), and universal T_c versus p relation. Although calculated T_c(x) dependences for l_min=3 and l_min=4 both remarkably correlate to the experimental T_c(x), we argue that the value l_min=4 gives a reasonable overall agreement.Comment: Four pages of text, 2 figures, corrected typing error in abstract: Y2+ and Ca3+ replaced by Y3+ and Ca2+. Thw word "each" added in page 3, line 4. Accepted in Superconductor Science and Technology, on 07.Apr.2008, after having been considerably revise

Variations in the squamous part of the occipital bone in medieval and contemporary cranial series from Bulgaria

The squamous part of the occipital bone is a place of many different variations. They are a result of faulty ossification in the occipital squama or due to the presence of sutural bones in the lambda region. As their differentiation is intricate because of the various criteria used, the issue of their recognition in the adult skull still remains difficult even though they can be clearly distinguished at a younger age. The aim of the present study was to compare the frequency of interparietal, preinterparietal and sutural bones in the lambda region in medieval male and female cranial series as well as between medieval and contemporary male series from Bulgaria. We also discuss the development of the occipital squama in order to set clearer criteria for further differentiation of such variations in the adult skull. In the reviewed 3 cranial series, the variations in the squamous portion of the occipital bone were observed with a low frequency. The incidence of preinterparietal bones was more common than the interparietal ones. The sutural bones in the lambda region were numerous in the series. No statistically significant sex or intergroup differences were established. So even if these anatomical variations are relatively rare, the understanding of them is of significance for many disciplines like anthropology, comparative and developmental anatomy, clinical and forensic medicine.

Radiofrequency catheter ablation in a child with Wolff-Parkinson-White syndrome and congenitally corrected transposition of the great arteries

The case is presented of a five-year-old boy with Wolff-Parkinson-White syndrome, who had undergone three surgical palliations because of congenitally corrected transposition of the great arteries, ventricular septal defect and pulmonary trunk near-atresia. Successful and uncomplicated radiofrequency catheter ablation of an accessory pathway located across the systemic atrioventricular valve ring was performed. The procedure was motivated by forthcoming corrective surgery, which would preclude venous access to the heart. This case emphasizes the need for precise timing of ablative therapy in such patients and shows that surgery itself may facilitate catheter ablation. (Cardiol J 2007; 14: 500-503

Thermally Induced Structural Transformations of Fe2O3 Nanoparticles Embedded in a Silica Matrix

XXV Konferencija Srpskog kristalografskog društva : Bajina Bašta, 2018

Crystallization of Fe2O3 and Gd2Si2O7 in Fe2O3/Gd2O3/SiO2 composite system

XXIV Konferencija Srpskog kristalografskog društva : Vršac, 2017

The Contribution of Alexander Friedmann to the Big Bang Theory

Рад се бави учешћем Aлександра Фридмана у теорији великог праска. Познат је по Фридмановим једначинама које описују покретни свемир, тј. свемир који може да се шири, скупља и буде статичан у зависности од параметра к (кривине), у FLRW метрици. Мада су те једначине добили и други, као што је Жорж Леметр (Georges Lemaitre), Фридман их је први добио и објавио 1922 године. Ове једначине се и данас користе за процене астрономских мерења.In this paper, we presented the participation of Alexander Friedmann in the Big Bang Theory. He is known for his Friedmman equations which describe the dynamic cosmos, ie. it expands, shrinks, and becomes static in depends on curvature parameter k in FLRW metric. By the way, these equations are given also, by others, such as, for example, Georges Lemaitre. Friedmann have got first equations and published in 1922 year. These equations are used for assessment of astronomical measurements today.Зборник радова конференције "Развој Астрономије Код Срба XI" ; 18-22. април 2021., БеоградProceedings of the Conference Development of Astronomy Among Serbs XI ; 18-22nd April, 2021 ; Belgrad

Asteroids – Celestrial Travelers

У раду се дискутују основне информације о астероидима, до којих се дошло након њиховог скоријег открића (XIX век). Имајући у виду да је Србија у време открића првог астероида (1801) још увек била под турском влашћу (за време чије владавине се није придавала посебна пажња науци), а да развој астрономије у нашој земљи, практично, почиње 1926-е године, започињање серије окрића астероида само десет година након тог догађаја (1936), од стране српских научника, представља изванредан успех. Посебно ако узмемо у обзир да је Србија у то време била у веома тешкој геополитичкој ситуацији, јер се налазила између два светска рата. Последично, више пажње у овом раду, посвећено је српском астроному, Петру Ђурковићу, који је започео серију открића астероида, и тиме отворио ново поглавље у српској астрономији.In this paper, we represented the participation of Abbe G. Lemaitre’s in the Big Bang Theory. He took part in theory of the expansion of cosmos and made Lemaître coordination system. He proposed the basic theoretical properties of the cosmos, which expands as predicted by Hubble’s law. Also he determined theoretically and experimental form of the Hubble law and first proposed the value of Hubble constant. He proposed model of cosmos which called “the Hypothesis of Primordial Atom” and later called it “the Begining of the World” or “the Cosmic Egg”.Зборник радова конференције "Развој Астрономије Код Срба XI" ; 18-22. април 2021., БеоградProceedings of the Conference Development of Astronomy Among Serbs XI ; 18-22nd April, 2021 ; Belgrad

Bi-Legendrian manifolds and paracontact geometry

We study the interplays between paracontact geometry and the theory of bi-Legendrian manifolds. We interpret the bi-Legendrian connection of a bi-Legendrian manifold M as the paracontact connection of a canonical paracontact structure induced on M and then we discuss many consequences of this result both for bi-Legendrian and for paracontact manifolds. Finally new classes of examples of paracontact manifolds are presented.Comment: to appear in Int. J. Geom. Meth. Mod. Phy

Facial soft tissue thicknesses in Bulgarian adults: relation to sex, body mass index and bilateral asymmetry

Background: The aim of the study is to measure the facial soft tissue thicknesses (STTs) in Bulgarians, to evaluate the relation of the STTs to the nutritional status, sex and bilateral asymmetry, and to examine the correlations between the separate STTs as well as between the STTs and body weight, height, and body mass index (BMI). In the present study, the facial STTs were measured on computed tomography scans of the head of Bulgarian adults. Materials and methods: The STTs were measured at 7 midline and 9 bilateral landmarks. The measurements were performed in the free software InVesalius in the axial and sagittal planes. The mean, standard deviation, minimum and maximum values, median and coefficient of variation were reported for the STT at each landmark according to the sex and BMI category. The BMI, sex and bilateral differences were assessed for statistical significance. Pearson correlation analysis was applied to assess the strength and direction of the relationships between the STTs and body height, weight and BMI, as well as between separate STTs. Results and Conclusions: The facial soft tissues in Bulgarian adults changed in accordance with the nutritional status of the individual and in both sexes all STTs augmented with the increasing BMI. For both normal and overweight BMI categories, males had more soft tissue at the majority of facial points than females, as the only exceptions were observed in the cheek zone, where STTs were thicker in females. Significant bilateral differences were observed in either sex and BMI category. Stronger correlations were established for the STTs in the jaw region and between the cheek and jaw soft tissues. Besides, the correlations between the homologous bilateral landmarks were among the strongest ones