Competition between different order parameters in a quasi-one-dimensional superconductor

We show that, under rather general assumptions, the phase diagram of a quasi-one-dimensional repulsive Fermi system consists of two ordered phases: the density wave, spin or charge, and the superconductivity. It is demonstrated that the symmetry of the superconducting order parameter is a non-universal property sensitive to microscopic details of the model. Three potentially stable superconducting states are identified: they are triplet $f$-wave, singlet $d_{x^2-y^2}$-wave, and $d_{xy}$-wave. Presence of multiple competing superconducting states implies that for a real material this symmetry is difficult to predict theoretically and hard to probe experimentally, since artifacts of theoretical approximations or variations in experimental conditions could tip the balance between the superconducting phases.Comment: 6 pages, 1 eps figur

Superconductivity without attraction in a quasi-one-dimensional metal

An array of one-dimensional conductors coupled by transverse hopping and interaction is studied with the help of a variational wave function. This wave function is devised as to account for one-dimensional correlation effects. We show that under broad conditions our system possesses the superconducting ground state even if no attraction is present. The superconducting mechanism is of many-body nature and deviates substantially from BCS. The phase diagram of the model is mapped. It consists of two ordered phases competing against each other: density wave, spin or charge, and unconventional superconductivity. These phases are separated by the first order transition. The symmetry of the superconducting order parameter is a non-universal property. It depends on particulars of the Hamiltonian. Within the framework of our model possible choices are the triplet $f$-wave and the singlet $d_{xy}$-wave. Organic quasi-one-dimensional superconductors have similar phase diagram.Comment: 12 pages, 2 Encapsulated PostScript figures, revtex4; the model's Hamiltonian is revised as compared to previous version, this revision affects prediction of the order parameter symmetr

Синтез нових спіроциклічних N-арилзаміщених 2-тіопіримідин-4,6-діонів

A convenient and efficient method for the synthesis of new unsaturated spiro-annulated N-aryl-4,6-dioxopyrimidine-2-thione derivatives has been developed. The resulting compounds can be potential biological active molecules or precursors for further chemical modification.Aim. To develop the methods for the synthesis of new unsaturated spiro-annulated 2-thiopyrimidine-4,6-dione derivatives, which can be used as potentially biological active molecules or precursors for their formation.Results and discussion. By condensation of N-aryl-substituted thioureas and allylmalonic acid using acetic anhydride or acetyl chloride the series of 5-allyl-substituted 2-thiopyrimidinediones has been synthesized. Their further alkylation with allyl bromide or metallyl chloride led to formation of 5,5-dialkenyl derivatives, which were converted to the corresponding unsaturated spirocyclic dioxopyrimidine-2-thiones by ring-closing metathesis. Experimental part. The synthesis of the starting compounds and title products was performed by preparative chemical methods, TLC and column chromatography, elemental analysis, NMR-spectroscopy.Conclusions. The efficient three-step synthetic route of new unsaturated spiro-annulated N-aryl-4,6-dioxopyrimidine-2-thione derivatives from the starting N-arylsubstituted thioureas and allylmalonic acid has been developed. The spiro-annulated products obtained can find application in biological and pharmaceutical science or as starting substrates for further chemical modification.Разработан удобный и эффективный метод синтеза новых ненасыщенных спиро-аннелированных N-арилзамещенных 2-тиопиримидин-4,6-дионов. Полученные соединения могут быть потенциальными биоактивными молекулами или исходными веществами для дальнейшей химической модификации.Цель работы – разработка методов получения новых ненасыщенных спиро-аннелированных производных 2-тиопиримидин-4,6-диона как потенциальных биологически активных соединений или полупродуктов для их получения.Результаты и их обсуждение. Конденсацией N-арилзамещенных тиомочевин и аллилмалоновой кислоты с использованием уксусного ангидрида или ацетилхлорида синтезирован ряд 5-аллилзамещенных 2-тиопиримидиндионов. При их последующем алкилировании аллилбромидом или металлилхлоридом получены 5,5-диалкенильные производные, которые реакциями метатезиса с закрытием цикла были конвертированы в соответствующие непредельные спироциклические диоксопиримидин-2-тионы.   Экспериментальная часть. Синтез исходных соединений и целевых продуктов классическими методами препаративной химии; очистка и идентификация полученных соединений проводились методами тонкослойной и колоночной хроматографии, методом элементного анализа, спектроскопией ЯМР.Выводы. Разработан эффективный трехстадийный путь получения из исходных тиомочевин и аллилмалоновой кислоты новых ненасыщенных спиро-аннелированных производных N-арил-4,6-диоксопиримидин-2-тиона. Полученные спироциклические продукты могут найти применение в биологии и фармацевтической науке, а также использоваться как исходные соединения для дальнейшей химической модификации.Розроблено зручний та ефективний метод синтезу нових ненасичених спіро-анельованих N-арилзаміщених 2-тіопіримідин-4,6-діонів. Одержані сполуки можуть бути потенційними біоактивними молекулами або прекурсорами для подальшої хімічної модифікації. Мета роботи – розробка методів одержання нових ненасичених спіро-анельованих похідних 2-тіопіримідин-4,6-діону як потенційних біологічно активних сполук або напівпродуктів для їх отримання. Результати та їх обговорення. КонденсацієюN-арилзаміщених тіосечовин та алілмалонової кислоти із застосуванням оцтового ангідриду або ацетилхлориду синтезовано серію 5-алілзаміщених 2-тіопіримідиндіонів. При подальшому їх алкілуванні алілбромідом або металілхлоридом одержано 5,5-діалкенільні похідні, які реакціями метатезису із закриттям циклу було перетворено на відповідні ненасичені спіроциклічні діоксопіримідин-2-тіони.Експериментальна частина. Синтез вихідних сполук та цільових продуктів класичними методами препаративної хімії; очистку та ідентифікацію отриманих сполук здійснено методами тонкошарової та колонкової хроматографії, елементним аналізом, ЯМР-спектроскопією.Висновки. Розроблено ефективний тристадійний шлях отримання з вихідних тіосечовин та алілмалонової кислоти нових ненасичених спіро-анельованих похідних N-арил-4,6-діоксопіримідин-2-тіону. Одержані спіроциклічні продукти можуть знайти застосування в біології та фармацевтичній науці, або використовуватись як вихідні сполуки для подальшої хімічної модифікації

Quantitative comparison of planar coded aperture imaging reconstruction methods

Imaging distributions of radioactive sources plays a substantial role in nuclear medicine as well as in monitoring nuclear waste and its deposit. Coded Aperture Imaging (CAI) has been proposed as an alternative to parallel or pinhole collimators, but requires image reconstruction as an extra step. Multiple reconstruction methods with varying run time and computational complexity have been proposed. Yet, no quantitative comparison between the different reconstruction methods has been carried out so far. This paper focuses on a comparison based on three sets of hot-rod phantom images captured with an experimental γ-camera consisting of a Tungsten-based MURA mask with a 2 mm thick 256 × 256 pixelated CdTe semiconductor detector coupled to a Timepix© readout circuit. Analytical reconstruction methods, MURA Decoding, Wiener Filter and a convolutional Maximum Likelihood Expectation Maximization (MLEM) algorithm were compared to data-driven Convolutional Encoder-Decoder (CED) approaches. The comparison is based on the contrast-to-noise ratio as it has been previously used to assess reconstruction quality. For the given set-up, MURA Decoding, the most commonly used CAI reconstruction method, provides robust reconstructions despite the assumption of a linear model. For single image reconstruction, however, MLEM performed best of all analytical reconstruction methods, but took on average 45 times longer than MURA Decoding. The fastest reconstruction method is the Wiener Filter with a run time 4.3 times faster compared to MURA Decoding and a mediocre quality. The CED with a specifically tailored training set was able to succeed the most commonly used MURA decoding on average by a factor between 1.37 and 2.60 and an equal run time

Feasibility of a Small, Rapid Optical-to-IR Response, Next Generation Gamma Ray Burst Mission

We present motivations for and study feasibility of a small, rapid optical to IR response gamma ray burst (GRB) space observatory. By analyzing existing GRB data, we give realistic detection rates for X-ray and optical/IR instruments of modest size under actual flight conditions. Given new capabilities of fast optical/IR response (about 1 s to target) and simultaneous multi-band imaging, such an observatory can have a reasonable event rate, likely leading to new science. Requiring a Swift-like orbit, duty cycle, and observing constraints, a Swift-BAT scaled down to 190 square cm of detector area would still detect and locate about 27 GRB per yr. for a trigger threshold of 6.5 sigma. About 23 percent of X-ray located GRB would be detected optically for a 10 cm diameter instrument (about 6 per yr. for the 6.5 sigma X-ray trigger).Comment: Elaborated text version of a poster presented at 2012 Malaga/Marbella symposiu

Study Of Mass Losses Of Cauliflower At Storage Depending On A Packing Way

Tissues of fresh vegetables are characterized by the high quantity of moisture (80…96 %), active metabolism, low resistance to mechanical lesions, are spoiled fast. Metabolism in cells of tissues, so mass losses, depends on the content of water and dry substances.It is impossible to manage abiotic factors under conditions of open soil. So, there appears a necessity to study the influence of abiotic factors on the process of mass decrease at cauliflower storage that gives a possibility to prognosticate its mass losses and aptitude to storage.The aim of the study was to analyze the influence of weather conditions of the vegetation period of cauliflower, volume, specific mass and porosity of heads and packing methods on the intensity of natural mass losses of cauliflower at storage. The research gives a possibility to decrease natural losses of cauliflower heads and to prolong the storage duration of it. Cauliflower mass losses at the expanse of water evaporation depend on weather conditions of the vegetation period of the plant. It has been established, that there is a middle force reverse connection with the coefficient correlation r=–0,465 between the intensity of water evaporation at cauliflower heads storage and GTC, middle force connection with the coefficient correlation r=0,437 – with the average day temperature, and strong reverse connection r=–0,776 with the relative air humidity. There was elaborated the regression equation that gives an understanding about mass losses of cauliflower heads, packed in PF, at the expanse of water evaporation.The intensity of water evaporation of cauliflower at storage depends on package method. At packing in a stretch-film (SF), the intensity of moisture decrease, % a day, was the least, equal to 0,30–0,31. The ratio between moisture losses to ones of dry substances was 0,45–0,68. At packing in a performed stretch-film (PSF), the intensity of moisture decrease, % a day, was higher a little – 0,37–0,43.The more storage duration of cauliflower of late ripeness was provided by individual packing of heads in a polyethylene stretch-film. This packing type provided less total natural losses of products: in Skywoker F1– 6,0 %, in Kasper F1 and Santamaria F1 – 6,3 %. Natural losses for a day in variants with using a stretch-film were within 0,05–0,06 % depending on hybrid

Kinky Behavior in Josephson Junctions

We analyze nonperturbatively the behavior of a Josephson junction in which two BCS superconductors are coupled through an Anderson impurity. We recover earlier perturbative results which found that a $\delta=\pi$ phase difference is preferred when the impurity is singly occupied and the on-site Coulomb interaction is large. We find a novel intermediate phase in which one of $\delta=0$ and $\delta=\pi$ is stable while the other is metastable, with the energy $E(\delta)$ having a kink somewhere in between. As a consequence of the kink, the $I-V$ characteristics of the junction are modified at low voltages.Comment: 7 pages, 7 encapsulated PostScript figures; figure 3 correcte

Векторный дисперсионный анализ изменчивости течений в Печорском море

The method of vector analysis of variance of vector random processes was used for the description of annual and tidal variability of sea currents in the Pechora Sea.There are the cases for description of temporal and spatial variability of sea currents.Для количественной характеристики годовой и приливной ритмики скорости течений использован метод дисперсионного анализа векторных случайных процессов. Приводятся примеры, характеризующие изменчивость течений во времени, по пространству и по глубине

The use of an antibacterial implant in the treatment of periprosthetic infection in an HIV-positive patient

Background: The frequency of occurrence of infectious complications after hip arthroplasty in HIV-infected patients is extremely high. Revision arthroplasty for periprosthetic infection is the leader (64%) among the causes of early revision interventions. The search for ways to increase the efficiency of the sanitizing stage of treatment due to antibacterial coatings of the endoprosthesis components continues.Objective: Demonstration of a clinical case of treatment of periprosthetic infection in an HIV-positive patient using a spacer and a femoral component of a hip joint endoprosthesis coated with linear Sp1 carbon chains and silver. 123 months after hip arthroplasty for stage 3 dysplastic coxarthrosis in HIV-positive patient of 42 years old developed an instability of the acetabular component with the growth of Staphylococcus aureus in punctates. A revision was performed with the removal of the endoprosthesis and the installation of an articulating spacer with the addition of antibiotics. 12 weeks later, a recurrence of periprosthetic infection occurred, and Enterococcus faecalis was detected in punctates. During re-endoprosthetics, there was an installation of an articulating spacer covered with a two-dimensionally ordered linear-chain carbon doped with silver, based on the Zimmer CPT femoral component and bone cement with antibiotics addition. After 3 months, the second stage of revision arthroplasty was performed with implantation of an individual acetabular component and a femoral component coated with two-dimensionally ordered linear-chain carbon doped with silver.Conclusion: 4 months after the operation the patient returned to work, 12 months later the functional results were satisfactory. The use of components coated with two-dimensionally ordered linear-chain carbon doped with silver in an HIV-positive patient with recurrent periprosthetic infection made it possible to stop the infectious process, improve limb function and the quality of life