50,835 research outputs found
'Otherwise it would be nothing but cruises': Exploring the subjective benefits of working beyond 65
The age at which statutory and private pensions are being paid is increasing in many countries so more people will need to work into their late 60s and beyond. Currently, relatively little is known about the meanings of work for people who actively choose to work into their later life. This qualitative study examined the subjective benefits of continuing in a paid job or self-employment beyond the age of 65 in the UK. Thirty one participants were interviewed, aged 65-91 years (median age 71), with 11 females and 20 males. Fourteen were working full-time; seventeen part-time. Interview transcripts were subject to thematic analysis. Although financial reward was acknowledged (more so by the female participants and the males who had young second families), there was more elaboration of the role of work in maintaining health, and enabling continuing personal development. Work was framed as increasing personal control over later life, lifestyle choices and active participation in wider society, an antithesis to âcruisingâ.The Institution of Occupational Safety and Health (UK)
Superalgebra Realization of the 3-algebras in N=6, 8 Chern-Simons-matter Theories
We use superalgebras to realize the 3-algebras used to construct N=6, 8
Chern-Simons-matter (CSM) theories. We demonstrate that the superalgebra
realization of the 3-algebras provides a unified framework for classifying the
gauge groups of the N \geq 5 theories based on 3-algebras. Using this
realization, we rederive the ordinary Lie algebra construction of the general
N=6 CSM theory from its 3-algebra counterpart, and reproduce all known examples
as well. In particular, we explicitly construct the Nambu 3-bracket in terms of
a double graded commutator of PSU(2|2). The N = 8 theory of Bagger, Lambert and
Gustavsson (BLG) with SO(4) gauge group is constructed by using several
different ways. A quantization scheme for the 3-brackets is proposed by
promoting the double graded commutators as quantum mechanical double graded
commutators.Comment: 29 pages, minor changes, published in JM
A Z spin-orbital liquid state in the square lattice Kugel-Khomskii model
We argue for the existence of a liquid ground state in a class of square
lattice models of orbitally degenerate insulators. Starting with the SU(4)
symmetric Kugel-Khomskii model, we utilize a Majorana Fermion representation of
spin-orbital operators to access novel phases. Variational wavefunctions of
candidate liquid phases are thus obtained, whose properties are evaluated using
Variational Monte Carlo. These states are disordered, and are found to have
excellent energetics and ground state overlap () when compared with exact
diagonalization on 16 site clusters. We conclude that these are spin-orbital
liquid ground states with emergent nodal fermions and Z gauge fields.
Connections to spin 3/2 cold atom systems and properties in the absence of
SU(4) symmetry are briefly discussed.Comment: 9 pages, 4 figures, 3 tables, published versio
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Rare Variant of Vastus Medialis Detected in vivo by Ultrasound and Confirmed by High-resolution MRI.
[Purpose] This report describes an unusual incidental finding during ultrasound investigation of the vastus medialis muscle. Volunteers underwent ultrasound scanning as part of an on-going investigation into the architecture of the vastus medialis muscle. [Subjects and Methods] The distal thighs of forty-one subjects were scanned using the Philips iU22 US system. An unusual muscle morphology was detected bilaterally in one subject, who then underwent a 3T Magnetic Resonance Imaging (MRI) scan in order to further investigate the muscle morphology. The subject in question was a 32â
year-old female who suffers from recurrent bilateral patellar dislocations. [Results] The MRI scan confirmed the ultrasound findings, and indicated the presence of the vastus medialis in two layers, with the VML continuing deep, separate from the VMO. [Conclusion] Although this rare variant has been been reported in previous cadaveric studies, we believe this to be the first report in the literature of this morphology in vivo. The biomechanical implications of this muscle arrangement are unknown, but it may not be without significance that this individual suffers from recurrent patellar dislocations
Felix Alexandrovich Berezin and his work
This is a survey of Berezin's work focused on three topics: representation
theory, general concept of quantization, and supermathematics.Comment: LaTeX, 27 page
Longitudinal detection of radiological abnormalities with time-modulated LSTM
Convolutional neural networks (CNNs) have been successfully employed in
recent years for the detection of radiological abnormalities in medical images
such as plain x-rays. To date, most studies use CNNs on individual examinations
in isolation and discard previously available clinical information. In this
study we set out to explore whether Long-Short-Term-Memory networks (LSTMs) can
be used to improve classification performance when modelling the entire
sequence of radiographs that may be available for a given patient, including
their reports. A limitation of traditional LSTMs, though, is that they
implicitly assume equally-spaced observations, whereas the radiological exams
are event-based, and therefore irregularly sampled. Using both a simulated
dataset and a large-scale chest x-ray dataset, we demonstrate that a simple
modification of the LSTM architecture, which explicitly takes into account the
time lag between consecutive observations, can boost classification
performance. Our empirical results demonstrate improved detection of commonly
reported abnormalities on chest x-rays such as cardiomegaly, consolidation,
pleural effusion and hiatus hernia.Comment: Submitted to 4th MICCAI Workshop on Deep Learning in Medical Imaging
Analysi
Extended supersolid phase of frustrated hard-core bosons on a triangular lattice
We study a model of hard-core bosons with frustrated nearest-neighbor hopping
() and repulsion () on the triangular lattice. We argue for a supersolid
ground state in the large repulsion () limit where a dimer
representation applies, by constructing a unitary mapping to the well
understood unfrustrated hopping case. This generalized 'Marshall sign rule'
allows us to establish the precise nature of the supersolid order by utilizing
a recently proposed dimer variational wavefunction, whose correlations can be
efficiently calculated using the Grassman approach. By continuity, a supersolid
is predicted over the wide parameter range, . This also establishes a
simple phase diagram for the triangular lattice spin 1/2 XXZ antiferromagnet.Comment: 5 pages, 4 figure
Andreev Bound states as a phase sensitive probe of the pairing symmetry of the iron pnictide superconductors
A leading contender for the pairing symmetry in the Fe-pnictide high
temperature superconductors is extended s-wave , a nodeless state in
which the pairing changes sign between Fermi surfaces. Verifying such a pairing
symmetry requires a special phase sensitive probe that is also momentum
selective. We show that the sign structure of pairing leads to surface
Andreev bound states at the sample edge. In the clean limit they only occur
when the edge is along the nearest neighbor Fe-Fe bond, but not for a diagonal
edge or a surface orthogonal to the c-axis. In contrast to d-wave Andreev bound
states, they are not at zero energy and, in general, do not produce a zero bias
tunneling peak. Consequences for tunneling measurements are derived, within a
simplified two band model and also for a more realistic five band model.Comment: 5 pages, 5 figure
Thermalized Displaced Squeezed Thermal States
In the coordinate representation of thermofield dynamics, we investigate the
thermalized displaced squeezed thermal state which involves two temperatures
successively. We give the wavefunction and the matrix element of the density
operator at any time, and accordingly calculate some quantities related to the
position, momentum and particle number operator, special cases of which are
consistent with the results in the literature. The two temperatures have
diffenent correlations with the squeeze and coherence components. Moreover,
different from the properties of the position and momentum, the average value
and variance of the particle number operator as well as the second-order
correlation function are time-independent.Comment: 7 pages, no figures, Revtex fil
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