9,962 research outputs found
Roles of nurses and parents caring for hospitalised children.
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
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
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
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 H, H 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 H, H 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
~10 M at 48d to a current dust mass of 0.1 M.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
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
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
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
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"
The result of Thouless, Ao and Niu (TAN), that the mutual friction parameter
, contradicts to the experiments made in rotating 3He-B by
Manchester group. The Manchester group observed that 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 at low
temperature, while due to the spectral flow 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
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
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