9,511 research outputs found
Building a grounded theory of engagement in mindfulness-based group therapy for distressing voices
Mindfulness based group therapy shows promise as a treatment for distressing voice-hearing. However, fostering engagement in groups can be challenging, and no theory of engagement in group therapy for distressing voices exists to guide practice or research.
This study employed Grounded Theory Method to build a theory of engagement in mindfulness based groups for distressing voices. Ten service-users and three therapists were interviewed about their experiences of such groups. The model that emerged involves a recursive process of investing in change and continually evaluating its usefulness and safety. Barriers to engagement were often overcome, but sometimes compromised perceived safety, leading to dropout. For others, group participation led to rewards, some of which were integrated beyond group termination. Group engagement can be encouraged by establishing universality around voice-hearing early, reducing uncertainty, sharing difficulties with mindfulness practices and mapping group progress to create a cohering sense of collaboration on therapy tasks
Black holes, cosmological singularities and change of signature
There exists a widespread belief that signature type change could be used to
avoid spacetime singularities. We show that signature change cannot be utilised
to this end unless the Einstein equation is abandoned at the suface of
signature type change. We also discuss how to solve the initial value problem
and show to which extent smooth and discontinuous signature changing solutions
are equivalent.Comment: 14pages, Latex, no figur
Dilatonic wormholes: construction, operation, maintenance and collapse to black holes
The CGHS two-dimensional dilaton gravity model is generalized to include a
ghost Klein-Gordon field, i.e. with negative gravitational coupling. This
exotic radiation supports the existence of static traversible wormhole
solutions, analogous to Morris-Thorne wormholes. Since the field equations are
explicitly integrable, concrete examples can be given of various dynamic
wormhole processes, as follows. (i) Static wormholes are constructed by
irradiating an initially static black hole with the ghost field. (ii) The
operation of a wormhole to transport matter or radiation between the two
universes is described, including the back-reaction on the wormhole, which is
found to exhibit a type of neutral stability. (iii) It is shown how to maintain
an operating wormhole in a static state, or return it to its original state, by
turning up the ghost field. (iv) If the ghost field is turned off, either
instantaneously or gradually, the wormhole collapses into a black hole.Comment: 9 pages, 7 figure
Complex lapse, complex action and path integrals
Imaginary time is often used in quantum tunnelling calculations. This article
advocates a conceptually sounder alternative: complex lapse. In the ``3+1''
action for the Einstein gravitational field minimally coupled to a Klein-Gordon
field, allowing the lapse function to be complex yields a complex action which
generates both the usual Lorentzian theory and its Riemannian analogue, and in
particular allows a change of signature between the two. The action and
variational equations are manifestly well defined in the Hamiltonian
representation, with the momentum fields consequently being complex. The
complex action interpolates between the Lorentzian and Riemannian actions as
they appear formally in the respective path integrals. Thus the complex-lapse
theory provides a unified basis for a path-integral quantum theory of gravity
involving both Lorentzian and Riemannian aspects. A major motivation is the
quantum-tunnelling scenario for the origin of the universe. Taken as an
explanation for the observed quantum tunnelling of particles, the complex-lapse
theory determines that the argument of the lapse for the universe now is
extremely small but negative.Comment: 12 pages, Te
Can brief mindfulness practice be of benefit? Evidence from an evaluation of group person-based cognitive therapy for depression
Comment on `Smooth and Discontinuous Signature Type Change in General Relativity'
Kossowski and Kriele derived boundary conditions on the metric at a surface
of signature change. We point out that their derivation is based not only on
certain smoothness assumptions but also on a postulated form of the Einstein
field equations. Since there is no canonical form of the field equations at a
change of signature, their conclusions are not inescapable. We show here that a
weaker formulation is possible, in which less restrictive smoothness
assumptions are made, and (a slightly different form of) the Einstein field
equations are satisfied. In particular, in this formulation it is possible to
have a bounded energy-momentum tensor at a change of signature without
satisfying their condition that the extrinsic curvature vanish.Comment: Plain TeX, 6 pages; Comment on Kossowski and Kriele: Class. Quantum
Grav. 10, 2363 (1993); Reply by Kriele: Gen. Rel. Grav. 28, 1409-1413 (1996
Note on Signature Change and Colombeau Theory
Recent work alludes to various `controversies' associated with signature
change in general relativity. As we have argued previously, these are in fact
disagreements about the (often unstated) assumptions underlying various
possible approaches. The choice between approaches remains open.Comment: REVTex, 3 pages; to appear in GR
Flow rate test bench: automated and compliant to ISO standards
he issue of measuring the flow rate through a pneumatic component is a critical one. Several methods exist, each with its own pros and cons regarding the type of gas, measurement range, and accuracy. ISO Standards, however, consider only a few of them: orifice plates, nozzles, Venturi nozzles, Venturi tubes. Although amenable to possible criticism, the International Organization for Standardization is an important reference. Designing a test bench according to its Standards is often more than reasonable: advantages include certification, assessment of test methods and accuracy, worldwide recognition. On the other hand, however detailed the Standards may be, they often lack the designer's (and perhaps the user's) point of view. This aspect leads to complicated realizations, low usability or long test execution times. This article proposes a flow rate test bench compliant to ISO Standards allowing a partially automated testing, rational installation, high configurability, user-friendliness, and accuracy. © 2012, Society for Experimental Mechanics
From Starburst to Quiescence: Testing AGN feedback in Rapidly Quenching Post-Starburst Galaxies
Post-starbursts are galaxies in transition from the blue cloud to the red
sequence. Although they are rare today, integrated over time they may be an
important pathway to the red sequence. This work uses SDSS, GALEX, and WISE
observations to identify the evolutionary sequence from starbursts to fully
quenched post-starbursts in the narrow mass range , and identifies "transiting" post-starbursts which are intermediate
between these two populations. In this mass range, of galaxies are
starbursts, are quenched post-starbursts, and are the
transiting types in between. The transiting post-starbursts have stellar
properties that are predicted for fast-quenching starbursts and morphological
characteristics that are already typical of early-type galaxies. The AGN
fraction, as estimated from optical line ratios, of these post-starbursts is
about 3 times higher () than that of normal star-forming
galaxies of the same mass, but there is a significant delay between the
starburst phase and the peak of nuclear optical AGN activity (median age
difference of Myr), in agreement with previous studies.
The time delay is inferred by comparing the broad-band near NUV-to-optical
photometry with stellar population synthesis models. We also find that
starbursts and post-starbursts are significantly more dust-obscured than normal
star-forming galaxies in the same mass range. About of the starbursts
and of the transiting post-starbursts can be classified as the
"Dust-Obscured Galaxies" (DOGs), while only of normal galaxies are
DOGs.The time delay between the starburst phase and AGN activity suggests that
AGN do not play a primary role in the original quenching of starbursts but may
be responsible for quenching later low-level star formation during the
post-starburst phase.Comment: 30 pages, 18 figures,accepted to Ap
Topological charge pumping in the interacting bosonic Rice-Mele model
We investigate topological charge pumping in a system of interacting bosons in the tight-binding limit, described by the Rice-Mele model. An appropriate topological invarient for the many-body case is the change of polarization per pump cycle, which we compute for various interaction strengths from infinite-size matrix-product-state simulations. We verify that the charge pumping remains quantized as long as the pump cycle avoids the superfluid phase. In the limit of hardcore bosons, the quantized pumped charge can be understood from single-particle properties such as the integrated Berry curvature constructed from Bloch stated, while this picture breaks down at finite interaction strengths. These two properties-robust quantized charge transport in an interacting system of bosons and breakdown of a single-particle invarient-could both be measured with ultracold quantum gases extending a previous experiment [Lohse et al., Nat. Phys. 12, 350 (2016)]. Furthermore, we investigate the entanglement spectrum of the Rice-Mele modal and argue that the quantized charge pumping is encoded in a winding of the spectral flow in the entanglement over a pump cycle
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