1,477 research outputs found
Horowitz's 'Impact of event scale'. Evolution of 20 years of use
Objective The main objective of this meta-analysis was to model the relations between a set of independent variables (age and gender of the trauma group, country where the study was done, year of publication, type of event, time elapsed between event and measurement) and stress symptoms. Methods Data from sixty-six studies which used Horowitzâ Impact of Event Scale (IES) to examine the psychological impact of a major life-event were meta-analyzed. Results Results from hierarchical regression analysis indicated that different types of event (episodes of illness and injury, natural and technological disaster, bereavement and loss, violence, sexual abuse, and war exposure) is a strong predictor of levels of intrusive and avoidant symptoms after a traumatic event. Intrusive and avoidant reactions reported by trauma victims tended to decrease linearly over time after the trauma. This finding was supported by the results reported by 20 different studies of stress reactions at two different time-points after various events. Gender and cultural difference were relatively insignificant while type of of event induced different levels of stress reactions as measured with the IES. Conclusion These data provide evidence for the value of the IES as a measure of stress reactions in a number of different populations. Data summarized here will be useful as a comparison resource in future studies of stress response syndromes
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Support during birth interacts with prior trauma and birth intervention to predict postnatal post-traumatic stress symptoms
Background: Many women experience childbirth as traumatic and 2% develop post-traumatic stress disorder (PTSD). This study examined the role of health practitioner support and personal control during birth as predictors of PTS symptoms, adjusting for vulnerability factors of prior trauma, depression, control beliefs and birth intervention. It also investigated interactions between support, prior trauma and birth intervention and their association with PTS symptoms.
Methods: A prospective longitudinal survey of 138 women recruited from UK NHS maternity clinics. Measures were taken in pregnancy, three-weeks and three-months after the birth.
Results: Support and control during birth were not predictive of postnatal PTS symptoms. However, support was predictive of PTS symptoms in a subset of women with prior trauma (beta = -.41, R2 = 16%) at both three-weeks and three-months postpartum. The interaction of birth intervention and support was associated with PTS symptoms three-months after birth, the relationship between support and PTS symptoms was stronger in women experiencing more intervention.
Conclusions: Low support from health practitioners is predictive of postnatal PTS symptoms in women who have a history of trauma. Longer-term effects of low support on postnatal PTS symptoms are also found in women who had more intervention during birth
Phase transitions and critical behavior of black branes in canonical ensemble
We study the thermodynamics and phase structure of asymptotically flat
non-dilatonic as well as dilatonic black branes in a cavity in arbitrary
dimensions (). We consider the canonical ensemble and so the charge inside
the cavity and the temperature at the wall are fixed. We analyze the stability
of the black brane equilibrium states and derive the phase structures. For the
zero charge case we find an analog of Hawking-Page phase transition for these
black branes in arbitrary dimensions. When the charge is non-zero, we find that
below a critical value of the charge, the phase diagram has a line of
first-order phase transition in a certain range of temperatures which ends up
at a second order phase transition point (critical point) as the charge attains
the critical value. We calculate the critical exponents at that critical point.
Although our discussion is mainly concerned with the non-dilatonic branes, we
show how it easily carries over to the dilatonic branes as well.Comment: 37 pages, 6 figures, the validity of using the effective action
discussed, references adde
Phase structure of black branes in grand canonical ensemble
This is a companion paper of our previous work [1] where we studied the
thermodynamics and phase structure of asymptotically flat black -branes in a
cavity in arbitrary dimensions in a canonical ensemble. In this work we
study the thermodynamics and phase structure of the same in a grand canonical
ensemble. Since the boundary data in two cases are different (for the grand
canonical ensemble boundary potential is fixed instead of the charge as in
canonical ensemble) the stability analysis and the phase structure in the two
cases are quite different. In particular, we find that there exists an analog
of one-variable analysis as in canonical ensemble, which gives the same
stability condition as the rather complicated known (but generalized from black
holes to the present case) two-variable analysis. When certain condition for
the fixed potential is satisfied, the phase structure of charged black
-branes is in some sense similar to that of the zero charge black -branes
in canonical ensemble up to a certain temperature. The new feature in the
present case is that above this temperature, unlike the zero-charge case, the
stable brane phase no longer exists and `hot flat space' is the stable phase
here. In the grand canonical ensemble there is an analog of Hawking-Page
transition, even for the charged black -brane, as opposed to the canonical
ensemble. Our study applies to non-dilatonic as well as dilatonic black
-branes in space-time dimensions.Comment: 32 pages, 2 figures, various points refined, discussion expanded,
references updated, typos corrected, published in JHEP 1105:091,201
Thermal switch of oscillation frequency in belousov- zhabotinsky liquid marbles
© 2019 The Authors. External control of oscillation dynamics in the Belousov- Zhabotinsky (BZ) reaction is important for many applications including encoding computing schemes. When considering the BZ reaction, there are limited studies dealing with thermal cycling, particularly cooling, for external control. Recently, liquid marbles (LMs) have been demonstrated as a means of confining the BZ reaction in a system containing a solid-liquid interface. BZ LMs were prepared by rolling 50 ml droplets in polyethylene (PE) powder. Oscillations of electrical potential differences within the marble were recorded by inserting a pair of electrodes through the LM powder coating into the BZ solution core. Electrical potential differences of up to 100mV were observed with an average period of oscillation ca 44 s. BZ LMs were subsequently frozen to 218C to observe changes in the frequency of electrical potential oscillations. The frequency of oscillations reduced upon freezing to 11mHz cf. 23 mHz at ambient temperature. The oscillation frequency of the frozen BZ LM returned to 23 mHz upon warming to ambient temperature. Several cycles of frequency fluctuations were able to be achieved
Ultrasensitive force and displacement detection using trapped ions
The ability to detect extremely small forces is vital for a variety of
disciplines including precision spin-resonance imaging, microscopy, and tests
of fundamental physical phenomena. Current force-detection sensitivity limits
have surpassed 1 (atto ) through coupling of micro or
nanofabricated mechanical resonators to a variety of physical systems including
single-electron transistors, superconducting microwave cavities, and individual
spins. These experiments have allowed for probing studies of a variety of
phenomena, but sensitivity requirements are ever-increasing as new regimes of
physical interactions are considered. Here we show that trapped atomic ions are
exquisitely sensitive force detectors, with a measured sensitivity more than
three orders of magnitude better than existing reports. We demonstrate
detection of forces as small as 174 (yocto ), with a
sensitivity 390 using crystals of Be
ions in a Penning trap. Our technique is based on the excitation of normal
motional modes in an ion trap by externally applied electric fields, detection
via and phase-coherent Doppler velocimetry, which allows for the discrimination
of ion motion with amplitudes on the scale of nanometers. These experimental
results and extracted force-detection sensitivities in the single-ion limit
validate proposals suggesting that trapped atomic ions are capable of detecting
of forces with sensitivity approaching 1 . We anticipate that
this demonstration will be strongly motivational for the development of a new
class of deployable trapped-ion-based sensors, and will permit scientists to
access new regimes in materials science.Comment: Expanded introduction and analysis. Methods section added. Subject to
press embarg
Supersymmetric AdS_4 black holes and attractors
Using the general recipe given in arXiv:0804.0009, where all timelike
supersymmetric solutions of N=2, D=4 gauged supergravity coupled to abelian
vector multiplets were classified, we construct the first examples of genuine
supersymmetric black holes in AdS_4 with nonconstant scalar fields. This is
done for various choices of the prepotential, amongst others for the STU model.
These solutions permit to study the BPS attractor flow in AdS. We also
determine the most general supersymmetric static near-horizon geometry and
obtain the attractor equations in gauged supergravity. As a general feature we
find the presence of flat directions in the black hole potential, i.e.,
generically the values of the moduli on the horizon are not completely
specified by the charges. For one of the considered prepotentials, the
resulting moduli space is determined explicitely. Still, in all cases, we find
that the black hole entropy depends only on the charges, in agreement with the
attractor mechanism.Comment: 25 pages, uses JHEP3.cl
Quantum Criticality and Holographic Superconductors in M-theory
We present a consistent Kaluza-Klein truncation of D=11 supergravity on an
arbitrary seven-dimensional Sasaki-Einstein space (SE_7) to a D=4 theory
containing a metric, a gauge-field, a complex scalar field and a real scalar
field. We use this D=4 theory to construct various black hole solutions that
describe the thermodynamics of the d=3 CFTs dual to skew-whiffed AdS_4 X SE_7
solutions. We show that these CFTs have a rich phase diagram, including
holographic superconductivity with, generically, broken parity and time
reversal invariance. At zero temperature the superconducting solutions are
charged domain walls with a universal emergent conformal symmetry in the far
infrared.Comment: 52 pages, 16 figures, 3 appendices; minor changes, version to be
published in JHE
Holographic studies of quasi-topological gravity
Quasi-topological gravity is a new gravitational theory including
curvature-cubed interactions and for which exact black hole solutions were
constructed. In a holographic framework, classical quasi-topological gravity
can be thought to be dual to the large limit of some non-supersymmetric
but conformal gauge theory. We establish various elements of the AdS/CFT
dictionary for this duality. This allows us to infer physical constraints on
the couplings in the gravitational theory. Further we use holography to
investigate hydrodynamic aspects of the dual gauge theory. In particular, we
find that the minimum value of the shear-viscosity-to-entropy-density ratio for
this model is .Comment: 45 pages, 6 figures. v2: References adde
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