Inhomogeneous states with checkerboard order in the t-J Model

We study inhomogeneous states in the t-J model using an unrestricted Gutzwiller approximation. We find that $pa\times pa$ checkerboard order, where $p$ is a doping dependent number, emerges from Fermi surface instabilities of both the staggered flux phase and the Fermi liquid state with realistic band parameters. In both cases, the checkerboard order develops at wave vectors $(\pm 2\pi/pa,0)$, $(0,\pm2\pi/pa)$ that are tied to the peaks of the wave-vector dependent susceptibility, and is of the Lomer-Rice-Scott type. The properties of such periodic, inhomogeneous states are discussed in connection to the checkerboard patterns observed by STM in underdoped cuprates.Comment: Published Versio

Anti-phase Modulation of Electron- and Hole-like States in Vortex Core of Bi2Sr2CaCu2Ox Probed by Scanning Tunneling Spectroscopy

In the vortex core of slightly overdoped Bi2Sr2CaCu2Ox, the electron-like and hole-like states have been found to exhibit spatial modulations in anti-phase with each other along the Cu-O bonding direction. Some kind of one-dimensionality has been observed in the vortex core, and it is more clearly seen in differential conductance maps at lower biases below +-9 mV

The multiwave IR-spectrometry as the tool for total hydrocarbon estimations

Проблема. Чтобы оценить суммарное содержание ( с Σ) углеводородов (УВ) в природных или сточных водах, их экстрагируют, измеряют обобщенный сигнал ( А Σ) в ИК-области спектра и находят показатель «содержание нефтепродуктов» ( с *) в пересчете на стандартное вещество Xст. Погрешность определения δс = ( с* - с Σ) / с Σ нередко превышает 50 % отн. Считают, что измерение сигнала при n аналитических длинах волн ( n > 1) повышает точность оценки с Σ, но исследования в этой области не проводились. Эксперимент. Готовили смеси алканов, циклоалканов и аренов в CCl₄, моделируя состав очищенных экстрактов. ИК-спектры регистрировали с помощью фурье-спектрометра FT-801. Поглощение каждой смеси измеряли тремя способами: 1 - при 2930 см⁻¹; 2 - при 2930, 2960 и 3030 см⁻¹; 3 - при 2855, 2930, 2960 и 3030 см⁻¹. Обобщенный сигнал вычисляли, суммируя результаты измерений при разных аналитических длинах волн (АДВ) по заранее выведенным формулам, включающим весовые коэффициенты. Показатель с * рассчитывали по градуировкам вида АΣ = f ( с ₓ); во всех случаях Хст - смесь Симарда. Находили и сравнивали значения δс при разных способах измерения АΣ. Чтобы объяснить выявленные закономерности, сопоставляли удельные коэффициенты поглощения разных УВ для каждого способа измерения А Σ. Результаты. При переходе от одноволновой к многоволновой спектрометрии сходимость результатов незначительно уменьшается, пределы обнаружения УВ растут, а коэффициенты поглощения индивидуальных УВ достоверно сближаются. Значения δс во всех случаях статистически значимы. Обобщающий их параметр RMSEP снижается в ряду (1) > (2) > (3). Методика (3) обеспечивает требуемую стандартами РФ точность оценки с Σ; даже для проб с высоким содержанием аренов δс < 15 % отн. Обсуждение результатов. Эксперимент показал, что одновременное использование нескольких АДВ при измерении аналитического сигнала действительно повышает точность оценки суммарного содержания УВ. Этот эффект объясняется нивелированием чувствительности определения разных УВ, например, алканов и аренов. Дальнейшее снижение погрешностей (при том же наборе АДВ) требует отказа от применения одномерных градуировок вида А Σ = f ( с ₓ). Если применять многомерную градуировку, заранее построенную по спектрам множества модельных углеводородных смесей (методика 3а), значения δс не превышают 8 % отн. В этом случае для большинства модельных смесей систематическая составляющая общей погрешности оказывается статистически незначимой. В « Заключении » охарактеризованы теоретическая значимость полученных результатов и перспективы их использования в гидрохимическом анализе.Problem. To evaluate the total concentration ( с Σ) of hydrocarbons (HСs) in natural or waste waters, it is possible to extract all HCs and to measure the generalized analytical signal in the certain IR spectral region. Then the total TPH index ( с *) can be determined in terms of the certain standard substance Xst. The error of this estimation δ с = ( с* - с Σ) / с Σ often exceeds 50 % rel. Specialists believe that the transition to multiwavelength signal measurement using n analytical wavelength values ( n > 1) improves the accuracy of с Σ estimations. No systematic investigations of this problem were conducted earlier. Experiment. The model mixtures of alkanes, cycloalkanes and arenes in CCl₄ were prepared to simulate the composition of refined extracts. IR-spectra were registered with FT-801 Fourier-spectrometer. The absorbance of each mixture was measured by three methods: (1) - only with 2930 cm⁻¹; (2) - with 2930, 2960 and 3030 cm⁻¹; (3) - with 2855, 2930, 2960 and 3030 cm⁻¹. The generalized signal was calculated for each mixture by summation of the measurands for different analytical wavelength values (AWV). Corresponding formulae with weighting factors were derived beforehand by the technique of least squares. The total index value ( c *) was determined by the calibration curve АΣ = f ( с ₓ), and Simard mixture was used as Xst in all cases. Calculated δ с values for standard methods (1) and (2) were compared with the data obtained using the new method (3). To interpret the results, the absorbance factors were compared for certain individual HCs. Results. The precision of generalized signals slightly decreases when the number of AWV grows. Simultaneous LODs are raised and the absorbance factors for individual HCs are leveled. The errors of сΣ evaluation via c* for all methods are statistically significant but they diminish when n grows. RMSEP parameter decreases with the methods line (1) > (2) > (3). Standard methods (1) and (2) do not provide the level of the result accuracy which is necessary according to Russian standards. The new multiwavelength method (3) provides the estimation accuracy which is required. For this method δ с values do not exceed 15 % in modulo, even for mixtures with the high content of arenes. Discussion. Our experiment showed that the simultaneous use of some AWVs really provides more reliable с Σ estimations. The main reason for this effect is the leveling of the absorption coefficients for various HCs, particularly for alkanes and arenes. Subsequent reduction of systematic errors may be secured if we will not use the univariate calibration curves. The multivariate calibration, obtained from the training set of the spectral data (method 3a), leads to accurate с Σ estimations. In this case δ с values do not exceed 8 %, and for the most part of model mixtures systematic errors are not statistically significant. In “Conclusion” the fundamental significances of obtained results and perspectives of their application in aqueous analysis are discussed

PECULIARITIES OF TERRITORIAL DISTRIBUTION OF TICK-BORNE ENCEPHALITIS MORBIDITY WITHIN IRKUTSK RESIDENTS

Irkutsk residents are infected, with, tick-borne encephalitis (TBE) mainly in Pribaykalie (Irkutsk region and Buryat Republic). TBE foci are rather various on this territory. Differences in some parameters of morbidity structure at the infection in different areas of this territory are reviewed, in this article

Experimental Modeling of Combined and Sequential Use of Transosseous and Intramedullary Blocking Osteosynthesis

Background. The introduction of the combined and sequential application of transosseous and intramedullary blocked osteosynthesis in limb lengthening requires an experimental study of the features of distraction regenerate. For small animals (in particular rabbits), special models are required.Aims. To develop experimental models of sequential and combined use of transosseous and intramedullary osteosynthesis in limb lengthening and substantiate their effectiveness.Materials and methods. A comparative study was carried out on 30 rabbits of the Soviet Chinchilla breed. Experimental models of sequential (EM-1) and combined (EM-2) application of transosseous and intramedullary osteosynthesis with preservation of the apparatus during the fixation period to simulate blockage were studied in the main groups. For comparison, sequential (comparison model 1 – CM-1) and combined (comparison model 2 – CM-2) use of transosseous and intramedullary osteosynthesis with dismantling of the apparatus at the end of distraction were modeled. The control was a regenerate formed according to the classical Ilizarov method. Radiographs were performed in dynamics, CT and morphological studies – at the end of the fixation period.Results. It was noted that regenerates of the same type in structure were formed in the EM-1 and CM-1 groups, as in the EM-2 and CM-2 groups. With successive methods, the spindle-shaped form of the regenerate prevailed, the formation of a pronounced periosteal component was noted. Powerful cortical plates, according to morphological studies, are formed from the periosteal and intermediate zones. With combined techniques, the cortical plates are formed thinner and predominantly from the periosteal component, the shape of the regenerate is closer to fusiform. In the comparison groups, the total time of surgical interventions was 25–50 % longer, in 50 % of cases there was a loss of length or deformation of the regenerate.Conclusions. The developed models of sequential and combined use of transosseous and intramedullary osteosynthesis for limb lengthening with preservation of fixation with an apparatus to simulate blocking have proven to be reliable in terms of fixation and easy to use on small laboratory animals.

The Current State of Natural Foci of Tick-Borne Encephalitis near Irkutsk City

Among main factors that influence intensity of tick-borne encephalitis foci one can distinguish the numbers of core vector (here, taiga tick Ixodes persulcatus) and the percentage of infected ticks. This paper shows the results of five-year monitoring of the tick-borne encephalitis focus, which is situated near Irkutsk city. Detected are the variations in numbers and infestation of the core vector of tick-borne encephalitis, both spatial and temporal. Cause-effect connection between these factors and human TBE morbidity is not found. However, morbidity rates of the Irkutsk population, observed on the annual basis, bear evidence of high activity and intensity of the foci. In this regard, a number of preventive measures is put forward, but further observations concerning all the parameters that influence foci activity are required

Thermal regimes of HTS cylinders operating in devices for fault current limitation

We reveal obstacles related to the application of HTS cylinders in current limiting devices based on the superconducting - normal state transition. It is shown that, at the critical current density achieved presently in bulk materials, and especially in BSCCO-2212, the required thickness of the cylinder wall in a full-scale inductive device achieves several centimeters. A simple mathematical model of the operation of an inductive fault current limiter (FCL) is used to show that such cylinders cannot be cooled in admissible time after a fault clearing and, hence, the inductive FCLs and current-limiting transformers employing BSCCO cylinders do not return to the normal operation in the time required. For the recovery even with a non-current pause in the circuit, the cylinders are needed with the critical current density by an order higher than the existed ones.Comment: 15 pages, 5 figure