687 research outputs found

    Photoemission kinks and phonons in cuprates

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    One of the possible mechanisms of high Tc superconductivity is Cooper pairing with the help of bosons, which change the slope of the electronic dispersion as observed by photoemission. Giustino et al. calculated that in the high temperature superconductor La1.85Sr0.15CuO4 crystal lattice vibrations (phonons) should have a negligible effect on photoemission spectra and concluded that phonons do not play an important role. We show that the calculations employed by Giustino et al. fail to reproduce huge influence of electron-phonon coupling on important phonons observed in experiments. Thus one would expect these calculations to similarly fail in explaining the role of electron-phonon coupling for the electronic dispersion.Comment: To appear in Nature as a Brief Communiction Arisin

    Measurement of Inhaled Corticosteroid Adherence in Inner-City, Minority Children with Persistent Asthma by Parental Report and Integrated Dose Counter

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    Parents often overreport adherence to asthma treatment regimens making accurate assessment of medication adherence in clinical practice difficult. This study was conducted to compare two adherence assessment methods clinicians may choose from when assessing patient inhaled corticosteroid (ICS) adherence: parental report and dose counter measurements of metered-dose inhaler (MDI) actuation. Participants included children (N = 50) with persistent asthma and their parents (N = 50). At enrollment, children received a new, marked ICS at the dose prescribed by their physician. Thirty days following enrollment, we measured ICS adherence by parental report and objectively, with a dose counter. Parental report overestimated ICS adherence when compared to dose counter. We found a statistically significant overall difference between parental report and objectively measured adherence. A dose counter that most ICS inhalers are equipped with may be a more reliable alternative measure of ICS adherence in a clinical practice setting

    Topological Wilson-loop area law manifested using a superposition of loops

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    We introduce a new topological effect involving interference of two meson loops, manifesting a path-independent topological area dependence. The effect also draws a connection between quark confinement, Wilson-loops and topological interference effects. Although this is only a gedanken experiment in the context of particle physics, such an experiment may be realized and used as a tool to test confinement effects and phase transitions in quantum simulation of dynamic gauge theories.Comment: Superceding arXiv:1206.2021v1 [quant-ph

    Щодо розрахунку деформацій зсуву в призматичних стержнях із полімерних матеріалів за умов розтягу з крученням

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    The process of creep of prismatic rods made of linear-viscoelastic polymeric materials under combined loading is considered. Defining equations that determine the relationship between strains, stresses and time are given in the form of a superposition of shear and bulk strain. The object of study is prismatic bars made of fiberglass ST-1. The area of linearity of the model is substantiated on the basis of the hypothesis of the existence of the creep function, which is built on the yield curves, a single diagram of long-term deformation and the statistical value of the quantile of statistics. The region of linear-elastic deformation is recognized based on the fulfillment of the condition of existence of a single creep function. The defining equations of the model contain a set of functions and coefficients determined from the basic experiments. On the basis of the relations between the kernels of the one-dimensional stress state, the parameters of the kernels under the condition of a complex stress state are determined. The linearity of viscoelastic properties is given by the Boltzmann-Voltaire equations. The fractional-exponential kernels of heredity are chosen as the kernels of heredity. The obtained values of the core parameters are used to calculate the creep deformations of prismatic bars made of ST-1 fiberglass under conditions of simultaneous tensile tension. Pages of the article in the issue: 115 - 118 Language of the article: UkrainianРозглядається процес повзучості призматичних стержнів з лінійно-в’язкопружних полімерних матеріалів за умов комбінованого навантаження. Визначальні рівняння, що описують залежність між деформаціями, напруженнями і часом, задаються у вигляді суперпозиції зсувної і об’ємної деформації. Об’єктом дослідження являються призматичні стержні зі склопластику СТ-1. Обґрунтовується область лінійності моделі, виходячи з гіпотези існування функції повзучості, побудованої по кривим податливості, єдиної діаграми довготривалого деформування і статистичного значення квантиля статистики. Визначається область лінійно-пружного деформування, виходячи з виконання умови існування єдиної функції повзучості. Визначальні рівняння моделі містять набір функцій і коефіцієнтів, що знаходяться з базових експериментів. На підставі співвідношень між ядрами одновимірного напруженого стану визначаються параметри ядер за умови складного напруженого стану. Лінійність в'язкопружних властивостей задається рівняннями Больцмана-Вольтера з дробово-експоненціальним ядром спадковості. Отримані значення параметрів ядер використовуються для розрахунку деформацій повзучості призматичних стержнів зі склоапластика СТ-1 за умов одночасної дії розтягу з крученням

    Large lattice distortions associated with the magnetic transition in La0.7Sr0.3MnO3

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    Colossal magnetoresistance (CMR) is associated with the phase transition from a metallic ferromagnetic to insulating paramagnetic phase, which can be controlled by an applied magnetic field. The insulating phase occurs due to trapping of the charge carriers by polaronic lattice distortions, which raise the resistivity. Theories based on local physics predict that the magnitude of the resistivity jump at Tc is determined by how much, on average, the amplitude of these distortions increases at the phase transition. Using neutron scattering, we measured the average distortion amplitude in La0.7Sr0.3MnO3. Surprisingly, its increase from below to above Tc is just as large as in other manganites, which have a much larger resistivity jump. This result suggests that the strength of CMR is determined not by the size of distortions, but by their cooperative nature specific to each compound. Existing theories need to be extended to include correlations between different unit cells to explain and predict the strength of CMR

    Особливості адміністративної відповідальності неповнолітніх

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    The need to consider the peculiarities of juvenile administrative liability is grounded by the increase in the number of offenses committed by them. Scientific approaches to the definition of the concepts of “administrative liability” and “administrative liability of minors” have been analyzed. In order to distinguish administrative liability from other types of legal liability, the author has studied the features of direct administrative liability. It has been established that juvenile administrative liability has features that are related to the age of a person who is brought to liability and are associated with the specific protection of the minor’s interests. The peculiarities of juvenile administrative liability have been distinguished and systematized; and it has been offered to divide them into material and procedural ones. Material peculiarities include: the age, when the specified type of liability comes due; predominantly educational nature of administrative liability; the fact that the purpose of administrative liability of a minor causes a lesser amount and degree of deprivation or restriction of the rights and freedoms compared to persons who are over 18 years old; the fact that administrative liability, in some cases, arises on general basis. The procedural peculiarities of juvenile administrative liability are related to its judicial application, the possibility of applying administrative and coercive measures to the parents of a minor, the participation of legal representatives and representatives in the representation of their interests, the obligation to notify the parents or persons who replace them, about minor’s detention, and with impossibility to apply administrative penalties as a substitute for criminal liability. The author has formulated his own definition of the concept of administrative liability of minors. It has been emphasized that the age peculiarities of juveniles should be taken into account while bringing a minor to administrative liability, and the nature of the committed administrative offense should be commensurate with the enforcement action.Рассмотрены особенности административной ответственности несовершеннолетних. Проанализированы научные подходы к определению понятий «административная ответственность» и «административная ответственность несовершеннолетних». Предложено особенности административной ответственности несовершеннолетних разделять на материальные и процессуальные. Сформулировано авторское определение понятия административной ответственности несовершеннолетних.Розглянуто особливості адміністративної відповідальності неповнолітніх. Проаналізовано наукові підходи до визначення понять «адміністративна відповідальність» і «адміністративна відповідальність неповнолітніх». Запропоновано особливості адміністративної відповідальності неповнолітніх поділяти на матеріальні та процесуальні. Сформульовано авторське визначення поняття адміністративної відповідальності неповнолітніх

    Quantum coherence of discrete kink solitons in ion traps

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    We propose to realize quantized discrete kinks with cold trapped ions. We show that long-lived solitonlike configurations are manifested as deformations of the zigzag structure in the linear Paul trap, and are topologically protected in a circular trap with an odd number of ions. We study the quantum-mechanical time evolution of a high-frequency, gap separated internal mode of a static kink and find long coherence times when the system is cooled to the Doppler limit. The spectral properties of the internal modes make them ideally suited for manipulation using current technology. This suggests that ion traps can be used to test quantum-mechanical effects with solitons and explore ideas for the utilization of the solitonic internal-modes as carriers of quantum information.Comment: 5 pages, 4 figures ; minor correction

    Herbivore Impact Versus Host Size Preference: Endophagous Insects on Heracleum mantegazzianum in Its Native Range

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    Classical biological control is a practice to control alien invasive weeds, but many introduced biological control agents exhibit only a weak negative impact on their targets. One reason is that prerelease impact studies in the natural environment are often difficult to carry out. Heracleum mantegazzianum Sommier and Levier (Apiaceae), which is native to the Caucasus, is a perennial noxious weed introduced into Europe and North America. We examined the impact and host size preference of different endophagous insect guilds in the weed's native range. Instead of the commonly used insect exclosure approach, we estimated plant vigor before and after herbivore attack under natural conditions. Endophagous herbivores were dominated by the weevil species Lixus iridis Olivier, Nastus fausti Reitter, and Otiorhynchus tatarchani Reitter (Coleoptera: Curculionidae), the fly Melanagromyza heracleana Zlobin (Diptera: Agromyzidae), and an unidentified root-boring agromyzid fly species. Most observed insect species exhibited a strong preference for either big or small plants, but none of them caused serious damage within the study period. Occurrence of root-feeding weevils was associated with weak plants, but because of their long larval development, it was not possible to assign this relationship clearly to either feeding damage or host size preference. A comparison with other studies indicated that mature H. mantegazzianum plants are quite tolerant to herbivory. Insects belonging to the feeding guilds studied here will probably not guarantee successful biological control. Further research should focus on earlier stages in the weed's life cycl
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