Comment on "Quantum Friction - Fact or Fiction?"

If quantum friction existed [J.B. Pendry, New J. Phys. 12, 033028 (2010)] an unlimited amount of useful energy could be extracted from the quantum vacuum and Lifshitz theory would fail. Both are unlikely to be true.Comment: Comment on J.B. Pendry, New J. Phys. 12, 033028 (2010

Repulsive Casimir Force in Chiral Metamaterials

We demonstrate theoretically that one can obtain repulsive Casimir forces and stable nanolevitations by using chiral metamaterials. By extending the Lifshitz theory to treat chiral metamaterials, we find that a repulsive force and a minimum of the interaction energy exist for strong chirality, under realistic frequency dependencies and correct limiting values (for zero and infinite frequencies) of the permittivity, permeability, and chiral coefficients.Comment: 4 pages, 4 figures, letter. submitted to Phys. Rev. Let

Technology for carrying out hydraulic fracturing using a new material 'nitinol'

The paper examines the causes of proppant backflow from a fracture to a well, and presents the main technologies for proppant control. The consequences of the removal of the fracture filler into the wellbore are determined. It has been noted that proppant backflow is most damaging to wells operated by electric centrifugal pumps. Existing methods of hydraulic fracturing are investigated, their disadvantages are indicated. A method has been developed for hydraulic fracturing with injection of compressed springs made of metal with the effect of 'memory' and restoring their shape under reservoir temperature stress. In the first stage, the remote section of the crack is filled with a fine fraction of ceramic proppant, and at the final stage of crack attachment, compressed springs made of nitinol material are fed. Using of material with a shape memory will allow the proppant packing to be compacted and the proppant to be 'locked' in the fracture. © Published under licence by IOP Publishing Ltd

ACUTE PANCREATITIS, DIAGNOSTICS AND PROGNOSIS

Purpose: to study the levels of lactoferrin (LF) and macroglobulin (MG) in the serum of patients with acute pancreatitis depending on the severity of inflammation and prediction of disease outcome.Materials and methods: 93 patients were observed with various forms of acute pancreatitis in the serum of them in the dynamics by radial immunodiffusion method there were investigated the concentration of MG and ELISA - the level of LF.Results: there was an increase in the level of WBF patients depending on various forms of acute pancreatitis and severity of inflammation and clear tendency to decrease with increasing level of MG severity in pancreatitis DIF sequence, SP, IP.Summary: In patients with acute pancreatitis there was a high concentration and low level of LF - MG which may indicate serious destructive processes in the pancreas. Following the treatment the level of LF decreases and MG - rises to normal which is an important diagnostic criterion for assessing the severity of the inflammatory process and the effectiveness of treatment for this disease. Considering these, indexes of LF and MG can be included into the standard of diagnostics and monitoring of treatment in various forms of acute pancreatitis

Relativistic nature of a magnetoelectric modulus of Cr_2O_3-crystals: a new 4-dimensional pseudoscalar and its measurement

Earlier, the magnetoelectric effect of chromium sesquioxide Cr_2O_3 has been determined experimentally as a function of temperature. One measures the electric field-induced magnetization on Cr_2O_3 crystals or the magnetic field-induced polarization. From the magnetoelectric moduli of Cr_2O_3 we extract a 4-dimensional relativistic invariant pseudoscalar $\widetilde{\alpha}$. It is temperature dependent and of the order of 10^{-4}/Z_0, with Z_0 as vacuum impedance. We show that the new pseudoscalar is odd under parity transformation and odd under time inversion. Moreover, $\widetilde{\alpha}$ is for Cr_2O_3 what Tellegen's gyrator is for two port theory, the axion field for axion electrodynamics, and the PEMC (perfect electromagnetic conductor) for electrical engineering.Comment: Revtex, 36 pages, 9 figures (submitted in low resolution, better quality figures are available from the authors

A Metamaterial Homogenization Approach with Application to the Characterization of Microstructured Composites with Negative Parameters

In this work, we develop a new systematic and self-consistent approach to homogenize arbitrary non-magnetic periodic metamaterials. The proposed method does not rely on the solution of an eigenvalue problem and can fully characterize the effects of frequency dispersion, magneto-electric coupling, and spatial dispersion, even in frequency band-gaps or when the materials are lossy. We formulate a homogenization problem to characterize a generic microstructured artificial material, and demonstrate that it is equivalent to an integral-differential system. We prove that this complex system can be reduced to a standard integral equation and solved using standard methods. To illustrate the application of the proposed method, we homogenize several important metamaterial configurations involving split ring resonators and metallic wires.Comment: 44 pages - Physical Review B (2007) (in press

Влияние медико-социальных факторов на отношение родителей к специфической профилактике инфекционных заболеваний у детей Саратовской области в период пандемии новой коронавирусной инфекции

Objective: to analyze the influence of medical and social factors on the attitude of parents to the specific prevention of infectious diseases in children during the pandemic of a new coronavirus infection. Material and methods. Anonymous questioning of parents on the attitude to vaccination was conducted. A specially designed questionnaire included questions about attitudes towards vaccines included in the National Immunization Schedule, as well as those not included in it, in particular, the desire of parents to vaccinate their children against COVID-19 was assessed. In total, 153 people aged 17 to 42 took part in the survey — parents of children aged 1 to 14 years. Results. All parents under 18 years of age support vaccination in accordance with the National Vaccination Calendar; 52.1% of parents aged 18—25 years (p < 0.001), 55.6% of parents aged 26—35 years (p < 0.001 compared to parents under 18 years old), and 66.7% of parents over 35 years old (p < 0.001 compared to parents under 18 years old and parents 18—35 years old). Conclusion. The main medical and social factors associated with the refusal to carry out preventive vaccinations for their children are: the age of parents under 35, incomplete higher education and trust in information received on the Internet. The results obtained indicate the need to determine the «risk group» among parents who express doubts about the need for vaccination. It is necessary to conduct educational programs for them in order to form a positive attitude towards the specific prevention of infectious diseases.Цель: анализ влияния медико-социальных факторов на отношение родителей к специфической профилактике инфекционных заболеваний у детей в период пандемии новой коронавирусной инфекции. Материалы и методы. Проводилось анонимное анкетирование родителей по вопросам отношения к вакцинопрофилактике. Специально разработанная анкета включала в себя вопросы: об отношении к вакцинам, входящим в Национальный календарь профилактических прививок, а также не входящим в него, в частности, оценивалось желание родителей вакцинировать своих детей против COVID-19. Всего в анкетировании приняли участие 153 человека в возрасте от 17 до 42 лет — родители детей в возрасте от 1 года до 14 лет. Результаты. Поддерживают вакцинацию в соответствии с Национальным календарём прививок все родители младше 18 лет; 52,1% родителей в возрасте 18—25 лет (р < 0,001 по сравнению с родителями младше 18 лет), 55,6% родителей в возрасте 26—35 лет (p < 0,001 по сравнению с родителями младше 18 лет), и 66,7% родителей старше 35 лет (p < 0,001 по сравнению с родителями младше 18 лет и родителями 18—35 лет). Заключение. Основными медико-социальными факторами, ассоциированными с отказом от проведения профилактических прививок своим детям являются: возраст родителей до 35 лет, неоконченное высшее образование и доверие к информации, полученной в сети Интернет. Полученные результаты свидетельствуют о необходимости определения «группы риска» среди родителей, высказывающих сомнения в пользе вакцинопрофилактики. Для этой группы родителей требуется проведение образовательных программ с целью формирования позитивного отношения к специфической профилактике инфекционных заболеваний

ВОЗРАСТНЫЕ РУБЕЖИ И МЕТАЛЛОГЕНИЧЕСКОЕ ПРОГНОЗИРОВАНИЕ ЗОЛОТОРУДНЫХ МЕСТОРОЖДЕНИЙ АКЖАЛ-БОКО-АШАЛИНСКОЙ РУДНОЙ ЗОНЫ (АЛТАЙСКАЯ АККРЕЦИОННО-КОЛЛИЗИОННАЯ СИСТЕМА)

We present new age constraints for igneous rocks and ore-metasomatic formations of the gold deposits in the Akzhal-Boko-Ashalin ore zone. In terms of their ore formation, these deposits correspond mainly to the orogenic type, which generally reflects specific metallogeny of the West Kalba gold-bearing belt in East Kazakhstan. Gold-quartz veins and mineralized zones of the gold-sulphide formation are confined to fractures feathering regional NW-striking and sublatitudinal faults. Their common features include the following: gold-bearing veinlet-disseminated pyrite-arsenopyrite ores that are localized in carbonaceous-sandy-schist and turbidite strata of different ages; structural-tectonic control of mineralization, numerous dikes of medium-basic compositions in ore-control zones; and the presence of post-orogenic heterochronous granite-granodiorite rocks, although their relation to gold-ore mineralization is not obvious. Igneous rocks of the study area have similar ages in a narrow range from 309.1±4.1 to 298.7±3.2 Ma, which is generally consistent with the previously determined age of granitoid massifs of gold-ore fields in East Kazakhstan. A younger age (292.9±1.3 to 296.7±1.6 Ma) is estimated for felsic rocks of the dyke complex. For the ore mineralization, the 40Ar/39Ar dating of sericite from near-ore metasomatites yields two age intervals, 300.4±3.4 Ma and 279.8±4.3 Ma. A gap between of the ages of the ore mineralization and the igneous rocks is almost 20 Ma, which may indicate that the processes of ore formation in the ore field continued in an impulse-like pattern for at least 20 Ma. Nevertheless, this confirms a relationship between the hydrothermal activity in the study area and the formation and evolution of silicic igneous rocks of the given age interval, which belong to the Kunush complex, according to previous studies. This interpretation is supported by reconstructed tectonic paleostress fields, showing that directions of the main normal stress axes changed during the ore mineralization stage, which is why the ore bodies significantly differ in their orientations. The above-mentioned data are the first age constraints for the study area. Additional age determinations are needed to further improve understanding of the chronology of ore-forming processes. Actually, all the features characterizing the gold mineralization of the Akzhal, Ashalin and Dauba ore fields, including the data on lithology, stratigraphy, structural tectonics, magmatism, isotope geochronology, mineralogy and geochemistry, can be used as criteria when searching for similar ore fields in East Kazakhstan.Представлены новые данные о возрасте магматических пород и рудно-метасоматических образований на золоторудных месторождениях Акжал-Боко-Ашалинской рудной зоны. Месторождения по своей рудно-формационной принадлежности более всего соответствуют орогенному типу золоторудных месторождений, что в целом отражает металлогеническую специфику Западно-Калбинского золотоносного пояса Восточного Казахстана. Оруденение представлено золотокварцевыми жилами и минерализованными зонами золотосульфидной формации и приурочено к разрывам, оперяющим региональные северо-западные и субширотные разломы. Общим для них является локализация золотосодержащих прожилково-вкрапленных пирит-арсенопиритовых руд в углеродисто-песчаносланцевых и турбидитовых толщах разного возраста, структурно-тектонический контроль оруденения, частое присутствие в рудоконтролирующих зонах даек среднеосновного состава, проявление посторогенных разновозрастных интрузивных гранит-гранодиоритовых пород, связь золотого оруденения с которыми неочевидна. Возраст магматических пород района показал близкие величины в узком интервале значений – от 309.1±4.1 до 298.7±3.2 млн лет, что в целом согласуется с ранее установленным возрастом гранитоидных массивов золоторудных полей Восточного Казахстана. Несколько более молодой возраст получен для кислых пород дайкового комплекса в диапазоне от 292.9±1.3 до 296.7±1.6 млн лет. Возраст формирования рудной минерализации, по данным 40Ar/39Ar исследования серицита из околорудных метасоматитов, показал два уровня: 300.4±3.4 и 279.8±4.3 млн лет. В целом, отрыв возраста минерализации от возраста магматических пород почти на 20 млн лет может свидетельствовать о том, что процессы рудообразования импульсно продолжались в рудном поле на протяжении как минимум 20 млн лет, что, тем не менее, подтверждает связь гидротермальной деятельности в районе со становлением и эволюцией кислых магматических пород данного возрастного уровня, относимых предшественниками к кунушскому комплексу. В пользу такой интерпретации свидетельствуют результаты восстановления полей тектонических палеонапряжений, показывающие, что в течение рудного этапа происходила смена направлений осей главных нормальных напряжений, обусловившая формирование рудных тел существенно различных направлений. Полученные возрастные характеристики являются первыми для района и должны быть в будущем дополнены для более четкого понимания хронологии рудообразующих процессов. Все приведенные характеристические признаки золотого оруденения Акжальского, Ашалинского и Даубайского рудных полей (литологические, стратиграфические, структурно-тектонические, магматические, изотопногеохронологические, минералого-геохимические) являются, по сути, критериями поиска подобного рода оруденения в Восточном Казахстане

A study of children’s search query formulation habits

The strategies children use for digital information search in educational settings are rarely explored. Open questions remain on such fundamental issues as to which information-seeking strategies children employ, how they construct queries, and if the strategies that are taught are effective when using modern search engines. We conducted an observation study with school children to gain insights into these questions. As a result of this study, we identified query-creation and query-reformulation strategies that children use

How kids see search: a visual analysis of internet search engines

Through previous studies into children’s internet search practice, we have gained insight into the taught strategies, information behaviour, and common errors children experience while searching. This paper analyses the visual structure of commonly-used internet search engines (ISEs) to explore how the interface and interaction design of ISEs may influence the search practices of children. Common features of ISEs are identified and the effects of query construction techniques on the visual presentation of information are reported. We use our observations to provide guidelines for the design and development of ISEs for childre