Low energy magnetic excitation spectrum of the unconventional ferromagnet CeRh3_{3}B2_{2}

The magnetic excitation spectrum of the unconventional ferromagnet CeRh$_{3}$B$_{2}$ was measured by inelastic neutron scattering on single crystal sample in the magnetically ordered and paramagnetic phases. The spin-wave excitation spectrum evidences high exchange interaction along the c-axis about two orders of magnitude higher than the ones in the basal plane of the hexagonal structure. Both strong out of plane and small in plane anisotropies are found. This latter point confirms that considering the $J$=5/2 multiplet alone is not adequate for describing the ground state of CeRh$_{3}$B$_{2}$. Quasielastic scattering measured above $T_{Curie}$ is also strongly anisotropic between the basal plane and the c-axis and suggests localized magnetism.Comment: 8 Figure

Competition and/or Coexistence of Antiferromagnetism and Superconductivity in CeRhIn5_5 and CeCoIn5_5

The Ce compounds CeCoIn$_5$ and CeRhIn$_5$ are ideal model systems to study the competition of antiferromagnetism (AF) and superconductivity (SC). Here we discuss the pressure--temperature and magnetic field phase diagrams of both compounds. In CeRhIn$_5$ the interesting observation is that in zero magnetic field a coexistence AF+SC phase exist inside the AF phase below the critical pressure $p_{\rm c}^\star \approx 2$ GPa. Above $p_{\rm c}^\star$ AF is suppressed in zero field but can be re-induced by applying a magnetic field. The collapse of AF under pressure coincides with the abrupt change of the Fermi surface. In CeCoIn$_5$ a new phase appears at low temperatures and high magnetic field (LTHF) which vanishes at the upper critical field $H_{\rm c2}$. In both compounds the paramagnetic pair breaking effect dominates at low temperature. We discuss the evolution of the upper critical field under high pressure of both compounds and propose a simple picture of the glue of reentrant magnetism to the upper critical field in order to explain the interplay of antiferromagnetic order and superconductivity.Comment: 6 pages, 7 figures, Manuscript for Proceedings of the International Conference on Quantum Criticality and Novel Phases (QCNP09, Dresden); to appear in pss(b

Electric field induced biaxiality and the electro-optic effect in a bent-core nematic liquid crystal

We report the observation of a biaxial nematic phase in a bent-core molecular system using polarizing microscopy, electro-optics, and dielectric spectroscopy, where we find that the biaxiality exists on a microscopic scale. An application of electric field induces a macroscopic biaxiality and in consequence gives rise to electro-optic switching. This electro-optic effect shows significant potential in applications for displays due to its fast high-contrast response. The observed electro-optic switching is explained in terms of the interaction of the ferroelectric clusters with the electric field

Biaxial order parameter in the homologous series of orthogonal bent-core smectic liquid crystals

The fundamental parameter of the uniaxial liquid crystalline state that governs nearly all of its physical properties is the primary orientational order parameter (S) for the long axes of molecules with respect to the director. The biaxial liquid crystals (LCs) possess biaxial order parameters depending on the phase symmetry of the system. In this paper we show that in the first approximation a biaxial orthogonal smectic phase can be described by two primary order parameters: S for the long axes and C for the ordering of the short axes of molecules. The temperature dependencies of S and C are obtained by the Haller's extrapolation technique through measurements of the optical birefringence and biaxiality on a nontilted polar antiferroelectric (Sm-APA) phase of a homologous series of LCs built from the bent-core achiral molecules. For such a biaxial smectic phase both S and C, particularly the temperature dependency of the latter, are being experimentally determined. Results show that S in the orthogonal smectic phase composed of bent cores is higher than in Sm-A calamatic LCs and C is also significantly large

DEVICES FOR TRAINING SWIMMERS AND WATER-POLO PLAYERS

Training devices for developing specific strength qualities to diagnose special working capaciity need to mimic the conditions of the competitive activity. This study developed devices for training swimmers and water-polo players

Hysteresis and Anchoring Energy in Ferroelectric Liquid Crystals

The frequency dispersion of the coercive force of Ferroelectric Liquid Crystals (FLC) cells has been detected and examined in the range of infralow (lower than 0.1 Hz) frequencies. To clarify the low-frequency dispersion, the model has been suggested, based on the arrangement of free charges and well describing the experimental curves. The method for determination of the energy of FLC anchoring at the surface, developed on the basis of the static hysteresis loop, has been proposed. The dependence of bistability and the anchoring energy upon the orientant layer thickness has experimentally been investigated

TRAINER COMPLEX FOR SPECIAL STRENGTH TRAINING OF SWIMMERS ON THE SURFACE AND IN WATER

The aim of the investigation is to elaborate the trainer complexes which would help to develop specific strength qualities of swimmers. The trainer apparatus (patent N 1614819 A 63B 69/10) consists of: frame fastened to the board of the swimming-pool vertically where carriages with shovels are located and can be rotated around the axis. The carriages are tied by the ropes with handles. The swimmer is on the board of the swimming-pool and grips the handles; he performs a rowing movement as if he were swimming. The shovels are in water in the low initial position and are turned and fixed in rest in a horizontal plane during the period of the rowing movement; they move up, creating resistance to the movement. In the upper position the carriages engage with shock-absorbers which accelerate the return of the carriage to the low initial position after finishing the rowing movement. The shovels turn the spin at that moment, fold up and create resistance to the downward carriage movement. The construction (patent N 1273130 A63B 69/12) includes a belt for the swimmer linked with a hindrance device attached to a directing rope, fastened above the water surface on the boards of the swimming-pool. The swimmer, moving from one board to another in the water, overcomes the given resistance of the hindrance device which moves after it. The power of the work done is determined according to the formula: N=L*P/t, where: L= length of the distance, P= value of the resistance, t= time. The construction (patent N 1621983 A63B 69/12), the prototype of which is the device "Swim-On" (USA), includes: handles for the hands linked by non-elastic cords to the swimming-pool boards, a loading device for different kinds of loads which is located on the post on the opposite board of the swimming-pool and linked by means of blocks and a cable with the belt of the swimmer. The swimmer is in the water in a stretching initial position, leaning on the handles during his performance, the rowing movement moves forward, overcoming the resistance of lifting the load. After finishing the rowing movement, the load lowers, creating the strength of the traction which is put on the belt, and as a result the swimmer returns to the initial position. The power of the work done is determined according to the formula: N=P*h*n, where: P= weight of the load, h= height of the lifting of the load, n= tempo of the movements. The constructions are being applied in the training process of the Lviv Physical Culture Institute and region team. The parametres of the loading: the size of the resistence (loading), the length of the distance, the time are given with the account of the fulfillment of the work at a certain level of power in accordance with the planned sports results

Logs Mining Based Approach to eCommerce Customer Classification

Fits.me ettevõte on arendanud veebipõhise rakenduse, mis aitab veebipoodide külastajatel valida õiget suurust riideid. Virtuaalse Proovikabiini rakendus logib kasutajate tegevusi ja salvestab sisestatud kehamõõdud andmebaasi. Lisaks kasutatakse Google Analytics andmeid, mis annab andmeid veebipoe külastuste sessioonidest ja sellistest kasutajate omadustest, nagu asukoht, kasutatud tarkvara ja riistvara. Käesoleva lõputöö põhiline ülesanne on analüüsida andmed ja õppida eraldama logidest kasulikku informatsiooni. Täpsemalt, me tahame leida meetodi veebipoe kasutajate grupeerimiseks.\n\rEsimesel etapil me leiame viisi erinevatest allikatest andmete kokkupanemiseks. Me agregeerime andmeid kasutajate- ja sessioonipõhisteks profiilideks. Andmed on puhastatud. Nende vorm on informatiivsem, ning andmed on valmis edaspidiseks analüüsiks. Andmete puhastamine ja eeltöötlus moodustavad lõputöös tähtsa osa.\n\rAnalüüsietapil me kasutame kahte andmete klassifitseerimismeetodit. Need on Otsustuspuud ja Naive Bayes. Me otsustame grupeerida kasutajaid e-kaubanduse jaoks ühe tähtsa tunnuse järgi: me klassifitseerime kasutajaid selle järgi, kas nad on teinud ostu või mitte, kas nad on tagastanud ostetud toodet või mitte. Klassifitseerimispuu ega Naive Bayes ei tuvastanud olulisi seoseid uuritud atribuutide ja ostukäitumise vahel. Kuid regressioonipuu osutus kasulikuks sarnase käitumisega kasutajate gruppide leidmises. See näitab, millise käitumismustri korral on ostu tegemise tõenäosus suurem ning millise käitumise korral väiksem.Fits.me Company has developed a web-tool which helps online shoppers to choose the right size of clothes. The application of Virtual Fitting Room logs users’ actions and saves values of entered body measurements into database. Additionally, Google Analytics is used to get data of online shops’ website visiting sessions, users’ characteristics like location, software and hardware. The main goal of the thesis is to analyse the data, learn to extract useful information. More precisely, we want to develop a method of grouping web-shop customers.\n\rAt the first stage we find a way to combine data from different sources. We aggregate the data into user- and session-based profiles. The data is cleaned. It has more informative form, and is ready for further analysis. Data cleaning and pre-processing form a significant part of the thesis.\n\rOn the analysis stage we use two methods for the data classification. These are Decision trees and Naïve Bayes. We decide to group customers by one of the important features for eCommerce: we classify user whether he/she makes a purchase or not, whether a user returns purchased item or not. Both, classification tree and Naïve Bayes did not find significant relationship between studied attributes and shopping behaviour. However, regression tree turned to be useful for finding the groups of users with similar behaviour. It shows patterns of behaviour which leads to higher probability of making purchase

Pure Non-Blocking LC Based Matrix Optical Switch for All-Optical Fibre Networks

New pure non-blocking matrix optical switch scheme for fiber networks is presented. The optical switch is based on conventional LCD technology, where the each pixel controls the polarization state of the light beam. The suggested switch offers several advantages over the conventional cross-point architecture such as: cost; complexity; size; adjustment; and optical performanc

Economic factors of political stability

Проблематика політичної стабільності є однією з найважливіших дослідницьких проблем сучасної політичної науки. Питання політичної стабільності не виникає саме по собі – тиск середовища, як внутрішнього, так і зовнішнього, на політичну систему є тією умовою, що примушує існуючу владу шукати нові способи та джерела стабілізації системи. Одним із найважливіших аспектів дослідження даної проблеми є визначення факторів та формування системи індикаторів, які впливають на формування політичної стабільності та дадуть змогу дати приблизну оцінку її стану. В даному дослідженні на підставі аналізу напрацювань західних учених та політичної практики зроблено спробу визначити особливості впливу соціально-економічних факторів (рівня економічного розвитку, динаміки росту ВВП, соціально-економічної нерівності) на політичну стабільність.The issue of political stability is one of the most important research problems of modern political science. The issue of political stability does not occur by itself – pressure of an internal and external environment on the political system is the condition, that makes the existing power to find new ways and sources of stabilization the system. One of the most important aspects of this problem is to determine the factors and the formation of a system of indicators, that influence the formation of political stability and will make it possible to give a rough estimate of its condition. In this study, based on analysis of reseaches of Western scholars and political practice, it was attempted to identify the peculiarities of the social and economic factors (level of economic development, the dynamics of GDP growth, socio-economic inequality) on political stability.Проблематика политической стабильности является одной из важнейших исследовательских проблем современной политической науки. Вопрос политической стабильности не возникает сам по себе – давление среды, как внутренней так и внешней, на политическую систему является тем условием, которое заставляет существующую власть искать новые способы и источники стабилизации системы. Одним из важнейших аспектов исследования данной проблемы является определение факторов и формирование системы индикаторов, которые влияют на формирование политической стабильности и позволят дать приблизительную оценку ее состояния. В данной работе на основании анализа исследований западных ученых и политической практики сделана попытка определить особенности влияния социальных и экономических факторов (уровня экономического развития, динамики роста ВВП, социально-економического неравенства) на политическую стабильность