9,962 research outputs found

    Roles of nurses and parents caring for hospitalised children.

    Get PDF
    This article reviews the literature on nurses' and parents' self-perceived roles when caring for hospitalised children, focusing on research conducted since the Department of Health published the National Service Framework for Children: Standard for Hospital Services in 2003. Three main themes emerge from the review: nurses' perceptions, parents' perceptions, and negotiation. Clarification of what nurses and parents consider to be their respective roles when caring for hospitalised children is a prerequisite for negotiation of those roles. The family's background, life experiences and circumstances influence the effectiveness of negotiation between nurses and parents. The article explores potential barriers to negotiation, including poor communication and failure to provide information. Limitations of the research and the implications for practice are considered

    Vortex Mass in BCS systems: Kopnin and Baym-Chandler contributions

    Full text link
    The Kopnin mass and the Baym-Chandler mass of the vortex have the same origin. Both represent the mass of the normal component trapped by the vortex. The Kopnin mass of the vortex is formed by quasiparticles localized in the vicinity of the vortex. In the superclean limit it is calculated as linear response exactly in the same way as the density of the normal component is calculated in homogeneous superfluid. The Baym-Chandler mass is the hydrodynamical (associated) mass trapped by vortex. It is analogous to the normal component formed by inhomogeneities, such as pores and impurities. Both contributions are calculated for the generic model of the continuous vortex core.Comment: revtex file, 3 pages, 1 figure. Initially appeared as Comment to the paper by E.B. Sonin et al "Vortex motion in charged and neutral superfluids: A hydrodynamic approach" (Phys. Rev. B 57, 575 (1998)). The calculation of the backflow mass is adde

    Classical and quantum regimes of the superfluid turbulence

    Full text link
    We argue that turbulence in superfluids is governed by two dimensionless parameters. One of them is the intrinsic parameter q which characterizes the friction forces acting on a vortex moving with respect to the heat bath, with 1/q playing the same role as the Reynolds number Re=UR/\nu in classical hydrodynamics. It marks the transition between the "laminar" and turbulent regimes of vortex dynamics. The developed turbulence described by Kolmogorov cascade occurs when Re >> 1 in classical hydrodynamics, and q << 1 in the superfluid hydrodynamics. Another parameter of the superfluid turbulence is the superfluid Reynolds number Re_s=UR/\kappa, which contains the circulation quantum \kappa characterizing quantized vorticity in superfluids. This parameter may regulate the crossover or transition between two classes of superfluid turbulence: (i) the classical regime of Kolmogorov cascade where vortices are locally polarized and the quantization of vorticity is not important; and (ii) the quantum Vinen turbulence whose properties are determined by the quantization of vorticity. The phase diagram of the dynamical vortex states is suggested.Comment: 12 pages, 1 figure, version accepted in JETP Letter

    A decade of ejecta dust formation in the Type IIn SN 2005ip

    Get PDF
    In order to understand the contribution of core-collapse supernovae to the dust budget of the early universe, it is important to understand not only the mass of dust that can form in core-collapse supernovae but also the location and rate of dust formation. SN 2005ip is of particular interest since dust has been inferred to have formed in both the ejecta and the post-shock region behind the radiative reverse shock. We have collated eight optical archival spectra that span the lifetime of SN 2005ip and we additionally present a new X-shooter optical-near-IR spectrum of SN 2005ip at 4075d post-discovery. Using the Monte Carlo line transfer code DAMOCLES, we have modelled the blueshifted broad and intermediate width Hα\alpha, Hβ\beta and He I lines from 48d to 4075d post-discovery using an ejecta dust model. We find that dust in the ejecta can account for the asymmetries observed in the broad and intermediate width Hα\alpha, Hβ\beta and He I line profiles at all epochs and that it is not necessary to invoke post-shock dust formation to explain the blueshifting observed in the intermediate width post-shock lines. Using a Bayesian approach, we have determined the evolution of the ejecta dust mass in SN 2005ip over 10 years presuming an ejecta dust model, with an increasing dust mass from ~108^{-8} M_{\odot} at 48d to a current dust mass of \sim0.1 M_{\odot}.Comment: Accepted by MNRAS, 17 pages, 11 figures. Author accepted manuscript. Accepted on 04/03/19. Deposited on 07/03/1

    Asymptotic motion of a single vortex in a rotating cylinder

    Full text link
    We study numerically the behavior of a single quantized vortex in a rotating cylinder. We study in particular the spiraling motion of a vortex in a cylinder that is parallel to the rotation axis. We determine the asymptotic form of the vortex and its axial and azimuthal propagation velocities under a wide range of parameters. We also study the stability of the vortex line and the effect of tilting the cylinder from the rotation axis.Comment: 9 pages, 10 figures. Considerable changes, now close to the published versio

    Vortex avalanches and the onset of superfluid turbulence

    Full text link
    Quantized circulation, absence of Galilean invariance due to a clamped normal component, and the vortex mutual friction are the major factors that make superfluid turbulence behave in a way different from that in classical fluids. The model is developed for the onset of superfluid turbulence that describes the initial avalanche-like multiplication of vortices into a turbulent vortex tangle.Comment: 4 page

    Vortex vs spinning string: Iordanskii force and gravitational Aharonov-Bohm effect

    Full text link
    We discuss the transverse force acting on the spinning cosmic string, moving in the background matter. It comes from the gravitational Aharonov-Bohm effect and corresponds to the Iordanskii force acting on the vortex in superfluids, when the vortex moves with respect to the normal component of the liquid.Comment: Latex file, 9 pages, no figures, references are added, version submitted to JETP Let

    From fabrics to island connections: Macroscopic and microscopic approaches to the prehistoric pottery of Antikythera

    Get PDF
    An intensive archaeological survey covering the entire extent of the island of Antikythera has recently revealed a sequence of prehistoric activity spanning the later Neolithic to Late Bronze Age, with cultural affiliations that variously link its prehistoric communities with their neighbours to the north, south and east. Here we present and discuss the results of a programme of both macroscopic and petrographie study of the prehistoric ceramics from Antikythera that defines a considerably varied group of fabrics and explores their implications with regard to regional potting traditions, on-island production versus imports, and changing patterns of human activity on the island through time. / Abstract in Greek: Μια εντατική επιφανειακή έρευνα που κάλυψε το σύνολο της έκτασης των Aντικυθήρων αποκάλυψε πρόσφατα μια ακολουθία προïστορικής δραστηριότητας που χρονολογείται από την προχωρημένη Nεολιθική μέχρι την ´Yστερη Eποχή του Xαλκού, και αντανακλά ποικίλες πολιτιστικές σχέσεις των προïστορικών κοινοτήτων του νησιού με γειτονικές περιοχές στα βόρεια, νότια καν ανατολικά. Eσώ παρουσιάςουμε και (τυςητάμε τα αποτελέσματα ενός προγράμματος μακροσκοπικής και πετρογραφικής μελέτης της προïστορικής κεραμικής από τα Aντικύθηρα, που προσδιορίςει μια σημαντική ποικνλία κεραμικών υλών και διερευνά τη σημασία τους σε σχέση με τις τοπικές παραδόσενς κεραμικής στην ευρύτερη περιοχή του Aιγαίου, την αντιδιαςτολή εγχώρνας παραγωγής καν ενσαγωγών, και τις δναχρονικές μεταβολές στο χαρακτήρα και την ένταση της ανθρώπινης δραστηριότητας στο νησί

    Comment on "Transverse Force on a Quantized Vortex in a Superfluid"

    Full text link
    The result of Thouless, Ao and Niu (TAN), that the mutual friction parameter d=0d_\perp =0, contradicts to the experiments made in rotating 3He-B by Manchester group. The Manchester group observed that d<0d_\perp <0 at low temperature and approaches 1 at high temperature. The reason of the contradiction is that TAN did not take into account the Iordanskii force on the vortex and the spectral flow force, which comes from the anomaly related to the low-energy bound states of fermions in cores of quantized vortices. The Iordanskii force is responsible for the negative d<0d_\perp <0 at low temperature, while due to the spectral flow dd_\perp approaches 1 at high temperature. Relation of the spectral flow anomaly with the paradoxes of the linear and angular momenta in gapless superfluids is discussed.Comment: revtex, 2 pages, submitted to Physical Review Letters as "Comment" to the paper D.J. Thouless, P. Ao and Q. Niu, Phys. Rev. Lett. 76, 3758 (1996

    High‐Resolution ν1 Spectrum of Propyne: Application of a Microcomputer‐Controlled Infrared‐Acoustic Color Center Laser Spectrometer

    Get PDF
    Development of a microcomputer‐controlled infrared‐acoustic color center laserspectrometer capable of scanning in 100 cm−1 sections over the wavelength range 2.2–3.3 μm with a resolution of 0.01 cm−1 (300 MHz) is reported. Application of the spectrometer to investigation of the ν1spectrum of propyne is demonstrated
    corecore