1,106 research outputs found

    Pion-Nucleon Scattering in Kadyshevsky Formalism: II Baryon Exchange Sector

    Get PDF
    In this paper, which is the second part in a series of two, we construct tree level baryon exchange and resonance amplitudes for πN\pi N / MBMB-scattering in the framework of the Kadyshevsky formalism. We use this formalism to formally implement absolute pair suppression, where we make use of the method of Takahashi and Umezawa. The resulting amplitudes are Lorentz invariant and causal. We continue studying the frame dependence of the Kadyshevsky integral equation using the method of Gross and Jackiw. The invariant amplitudes, including those for meson exchange, are linked to the phase-shifts using the partial wave basis.Comment: 49 page

    Spin-mediated dissipation and frequency shifts of a cantilever at milliKelvin temperatures

    Get PDF
    We measure the dissipation and frequency shift of a magnetically coupled cantilever in the vicinity of a silicon chip, down to 2525 mK. The dissipation and frequency shift originates from the interaction with the unpaired electrons, associated with the dangling bonds in the native oxide layer of the silicon, which form a two dimensional system of electron spins. We approach the sample with a 3.433.43 μ\mum-diameter magnetic particle attached to an ultrasoft cantilever, and measure the frequency shift and quality factor as a function of temperature and the distance. Using a recent theoretical analysis [J. M. de Voogd et al., arXiv:1508.07972 (2015)] of the dynamics of a system consisting of a spin and a magnetic resonator, we are able to fit the data and extract the relaxation time T1=0.39±0.08T_1=0.39\pm0.08 ms and spin density σ=0.14±0.01\sigma=0.14\pm0.01 spins per nm2^2. Our analysis shows that at temperatures 500\leq500 mK magnetic dissipation is an important source of non-contact friction.Comment: 5 pages, 3 figure

    A method for mechanical generation of radio frequency fields in nuclear magnetic resonance force microscopy

    Get PDF
    We present an innovative method for magnetic resonance force microscopy (MRFM) with ultra-low dissipation, by using the higher modes of the mechanical detector as radio frequency (rf) source. This method allows MRFM on samples without the need to be close to an rf source. Furthermore, since rf sources require currents that give dissipation, our method enables nuclear magnetic resonance experiments at ultra-low temperatures. Removing the need for an on-chip rf source is an important step towards a MRFM which can be widely used in condensed matter physics.Comment: 7 pages, 5 figures, to be submitted to Physical Review Applie

    Detection and control of individual nuclear spins using a weakly coupled electron spin

    Full text link
    We experimentally isolate, characterize and coherently control up to six individual nuclear spins that are weakly coupled to an electron spin in diamond. Our method employs multi-pulse sequences on the electron spin that resonantly amplify the interaction with a selected nuclear spin and at the same time dynamically suppress decoherence caused by the rest of the spin bath. We are able to address nuclear spins with interaction strengths that are an order of magnitude smaller than the electron spin dephasing rate. Our results provide a route towards tomography with single-nuclear-spin sensitivity and greatly extend the number of available quantum bits for quantum information processing in diamond

    Distinct enzymatic responses in mice exposed to a range of low doses of ozone.

    Get PDF
    Short-term exposure of mice to low O3 doses, as defined by the product of concentration and exposure time (ct), was observed to induce alterations in two enzyme systems: first, that leading to changes in hepatic reduced ascorbic acid (RAA) content, and second to changes in plasma creatine phosphokinase (CPK) activity. RAA alterations were noticed immediately, 30 min and 120 min after termination of the exposure period, whereas CPK showed alterations immediately and 15 min after termination of the exposure. Later determinations, i.e., 24 hr after O3 exposure for RAA and 30 min after 03 exposure for CPK, revealed no significant differences when compared to control animals. Although differences in sensitivity existed, the dose response curves for both systems were more or less similar, showing a short decrease for the initial very low O3 doses, followed by a profound rise and a gradual decrease to control levels for subsequent ct doses. Exceptions were the 30 min curve for RAA and the immediate curve for CPK in so far as that both showed an additional depression. Neither plasma histamine nor plasma lactic acid dehydrogenase (LDH3) were observed to be altered by the range of O3 doses employed. These findings were explained on the basis of adaptation of the organism to a potentially noxious O3 stimulus by enhanced metabolic processes: a weak stimulus leading to only a small adjustment, and stronger stimuli to elevated enzyme activity as well. With increasing doses of O3 this elevation in enzyme activity was found to be gradually diminished, possibly due to a steadily growing demand, leaving the overshoot becoming continually smaller until a balanced state is achieved

    Searching for plasticity in dissociated cortical cultures on multi-electrode arrays

    Get PDF
    We attempted to induce functional plasticity in dense cultures of cortical cells using stimulation through extracellular electrodes embedded in the culture dish substrate (multi-electrode arrays, or MEAs). We looked for plasticity expressed in changes in spontaneous burst patterns, and in array-wide response patterns to electrical stimuli, following several induction protocols related to those used in the literature, as well as some novel ones. Experiments were performed with spontaneous culture-wide bursting suppressed by either distributed electrical stimulation or by elevated extracellular magnesium concentrations as well as with spontaneous bursting untreated. Changes concomitant with induction were no larger in magnitude than changes that occurred spontaneously, except in one novel protocol in which spontaneous bursts were quieted using distributed electrical stimulation

    Семантика имен и поэтика их перечислений

    Get PDF
    Описаны факторы, влияющие на содержательность и эстетическую значимость перечислений поэтонимов в художественных текстах. На ряде примеров из творчества А. С. Пушкина представлены перемены, происходящие в совокупной семантике и поэтике рядов собственных имен в различных контекстах. Показаны некоторые теоретически возможные модели реализации "списков" поэтонимов. Намечены пути дальнейшего изучения художественно значимых перечислений.Обговорюються фактори, які впливають на змістовність та естетичну значущість перерахувань поет онімів у художніх текстах. На низці прикладів з творчості О.С. Пушкіна представлені зміни, які відбуваються у сукупній семантиці й поетиці рядів власних імен у різноманітних контекстах. Показані деякі теоретичні можливості моделювання переліків онімів. Накреслені шляхи подальшого вивчення художньо значимих переліків онімів.The factors which influence pithiness and the aesthetic inventory of poetonyms in art texts are described. On a number of examples from Pushkin works the changes occurring in cumulative semantics and poetics of numbers of proper names in various contexts are presented. Some theoretically possible models of realization of "lists" of onyms are shown. Ways of the further studying of artily significant transfers are planned

    Формування індивідуального стилю у творчості народних майстрів художньої обробки дерева (на прикладі різьбярських династій Шкрібляків та Корпанюків)

    Get PDF
    У статті розглянуто творчість видатних різьбярських династій Шкрібляків та Корпанюків з позиції формування власного стилю в кожного з майстрів та їхнього впливу на зародження Косівської школи художньої обробки дерева. Особливу увагу приділено тим технічним і технологічним новаціям, які застосовували у своїх творах різьбярі, та тим композиційним прийомам, які вирізняли їхні вироби з-поміж інших.В статье рассматривается творчество выдающихся династий резчиков Шкрибляков и Корпанюков с точки зрения формирования собственного стиля у каждого из мастеров и их влияния на зарождение Косовской школы художественной обработки дерева. Особое внимание уделяется тем техническим и технологическим новациям, которые использовали резчики в своих произведениях, и композиционным приёмам, выделяющим их изделия среди прочих.There is an observation of creative work of the illustrious Shkribliak and K orpaniuk houses of carvers from a position of formation of a master’s individual style and proceeding from each master’s impact on the K osiv artistic carving school’s origin. The author pays a specific attention to the technical and technological innovations which are put into practice by a carver as well as to the composition wethods which differ carver’s wares from the rest