Phase Transitions In Two Planar Lattice Models And Topological Defects: A Monte Carlo Study

Monte Carlo simulation has been performed in the planar P(_{2}) and P(_{4}) models to investigate the effects of the suppression of topological defects on the phase transition exhibited by these models. Suppression of the 1/2-defects on the square plaquettes in the P(_{2}) model leads to complete elimination of the phase transition observed in this model. However in the P(_{4}) model, on suppressing the single 1/2-defects on square plaquettes, the otherwise first order phase transition changes to a second order one which occurs at a higher temperature and this is due to presence of large number of 1/2-pair defects which are left within the square plaquettes. When we suppressed these charges too, complete elimination of phase transition was observed.Comment: Related work has been presented in 22 nd International Conference on Statistical Physics, STATPHYS22, IISC Bangalore, Indi

Landau Level Crossings and Extended-State Mapping in Magnetic Two-dimensional Electron Gases

We present longitudinal and Hall magneto-resistance measurements of a ``magnetic'' two-dimensional electron gas (2DEG) formed in modulation-doped Zn$_{1-x-y}$Cd$_{x}$Mn$_{y}$Se quantum wells. The electron spin splitting is temperature and magnetic field dependent, resulting in striking features as Landau levels of opposite spin cross near the Fermi level. Magnetization measurements on the same sample probe the total density of states and Fermi energy, allowing us to fit the transport data using a model involving extended states centered at each Landau level and two-channel conduction for spin-up and spin-down electrons. A mapping of the extended states over the whole quantum Hall effect regime shows no floating of extended states as Landau levels cross near the Fermi level.Comment: 10 pages, 4 figures, submitted to Phys. Rev.

Cutting Edge Geometry Effect on Plastic Deformation of Titanium Alloy

The paper presents experimental studies of ОТ4 titanium alloy machining with cutting edges of various geometry parameters. Experiments were performed at a low speed by the scheme of free cutting. Intensity of plastic shear strain was set for defining of cutting edge geometry effect on machining. Images of chip formed are shown. Estimation of strain magnitude was accomplished with digital image correlation method. Effect of rake angle and cutting edge angle has been studied. Depth of deformed layer and the area of the plastic strain is determine. Results showed that increasing the angle of the cutting edge inclination results in a change the mechanism of chip formation

The Hagedorn transition in non-commutative open string theory

The Hagedorn transition in non-commutative open string theory (NCOS) is relatively simple because gravity decouples. For NCOS theories in no more than five spacetime dimensions, the Hagedorn transition is second order, and the high temperature phase involves long, nearly straight fundamental strings separating from the D-brane on which the NCOS theory is defined. Above five spacetime dimensions interaction effects become important below the Hagedorn temperature. Although this complicates studies of the transition, we believe that the high temperature phase again involves long strings liberated from the bound state.Comment: 22 pages, latex, one figure. v2: references added. v3: more references adde

ФОРМИРОВАНИЕ ТУАЛЕТНЫХ НАВЫКОВ У ДЕТЕЙ ИЗ СЕМЕЙ ОБЩЕЙ ПОПУЛЯЦИИ И СЕМЕЙ С ВЫСОКИМ СОЦИАЛЬНО-ЭКОНОМИЧЕСКИМ СТАТУСОМ. СРАВНИТЕЛЬНОЕ ИССЛЕДОВАНИЕ

Goal: to compare the main parameters of toilet skills formation in between children of the common population and those from families with a high social and economic status. Methods: 1068 parents with children 2–5 years of age were questioned using a specially developed questionnaire. Results: 1012 children from the common population (CP) and 56 children from families with a relatively high economic and social status (RHESS) were studied. The average age at the beginning of toilet training appeared to be the same 15,17 ± 0,23 months (CP) and 15,6 ± 0,8 months (RHESS). In the CP group 29.5% of parents started toilet training before their children reached the age of 1 year — which is twice more often than in the RHESS group. The RHESS children finish toilet training approx. 1.9 months earlier. The overall training turned out to be shorter in the RHESS group by more than 2 months: 10,5 ± 0,6 against 12,88 ± 0,41 months (р < 0,05). Serious differences were discovered in the teaching methods: parents from the CP group are more inclined towards forced placement of the child onto the pot and to more active actions demonstrating at the same time more variety in methodology, while in the RHESS group the methodology is more homogeneous with techniques oriented at the child’s choice and a moderate parental activity are dominating. Conclusion. The methods of child toilet training in families with a high economic and social status is different from those most popular in the general population. The training in the RHESS group is slightly faster and is concluded earlier.  Цель исследования: сравнение основных параметров формирования навыков туалета у детей из семей общей популяции и детей из семей с высоким социально-экономическим статусом. Методы. Проведено анкетирование 1068 родителей детей в возрасте от 2 до 5 лет с помощью специально разработанного опросника. Результаты. Всего обследовано 1012 детей общей популяции (ОП) и 56 детей из семей с относительно высоким социально-экономическим статусом (ВСЭС). Средний возраст детей к моменту начала обучения навыкам туалета в группах оказался одинаковым: 15,17 ± 0,23 мес (группа ОП) и 15,6 ± 0,8 мес (группа ВСЭС). В группе ОП обучение в возрасте ребенка до 1 года жизни начинало 29,5% родителей ― в два раза чаще, чем в группе ВСЭС. Дети из группы высокого социально-экономического статуса завершают обучение примерно на 1,9 мес раньше. Средняя продолжительность обучения туалетным навыкам от самых первых попыток обучения до полного освоения туалетных навыков в группе ВСЭС оказалась более чем на 2 мес короче, чем в группе ОП: 10,5 ± 0,6 против 12,88 ± 0,41 мес (р < 0,05). Выявлены существенные различия в методологии обучения: родители группы ОП более привержены к принудительным высаживаниям ребенка на горшок и более активным действиям при большей вариабельности методологии, тогда как в группе ВСЭС методология более однородна и доминируют техники, ориентированные на выбор ребенка и умеренную активность родительских действий в основной стадии обучения. Заключение. Методология обучения детей навыкам туалета в семьях с высоким социально-экономическим статусом отличается от наиболее популярных в общей популяции. Обучение туалетным навыкам в группе ВСЭС несколько быстрее и завершается также несколько ранее.

Composite silicide-oxide coatings on refractory metals

Translated from Russian (Fiz. Khim. Obrab. Mater. 1995 (6) p. 51-57)SIGLEAvailable from British Library Document Supply Centre-DSC:9023.190(VR-Trans--9230)T / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Interference immunity fire alarm system on the basis of a laser fiber optic smoke detector

Приведено описание конструкции лазерного оптоволоконного дымового извещателя, обеспечивающего повышенную устойчивость к воздействию электромагнитных полей систем пожарной сигнализации, использующих его в качестве средства обнаружения пожара. Обнаружение дыма данным извещателем осуществляется по уменьшению регистрируемой приемником излучения интенсивности светового потока вследствие частичного поглощения и рассеянии его на частицах дыма. Высокая помехоустойчивость системы пожарной сигнализации на базе лазерного оптоволоконного извещателя, обусловлена отсутствием подводимых к извещателю от прибора приемо-контрольных длинных электропроводных линий питания и связи, играющих роль эффективных приемных антенн случайных электромагнитных полей. Изложены результаты апробации работоспособности предложенной конструкции извещателя, свидетельствующие о его высокой чувствительности обнаружения возгорания. The work describes the construction of a laser fiber-optic smoke detector that has enhanced immunity to electromagnetic fields of a fire alarm system, by using it as a mean of fire detection. The assessment of smoke concentration in this detector is conducted by reduction of the registered luminous flux radiation due to its partial absorption and scattering on the smoke particles. High interference immunity of fire alarm systems based on the use of a laser fiber-optic detector is conditioned by the absence of long power supply lines and connection with the control device that are used as effective receiving aerials of random electromagnetic fields. The results are presented on the tests for efficiency of the proposed construction of the detector proving its high sensitivity of fire detection