1,658 research outputs found
Clinical evaluation of Behavioral Activation Treatment of anxiety (BATA) in three older adults
This paper describes three single-case experimental evaluations of behavioral activation treatment of anxiety (BATA) applied with a 51-year-old male, a 62-year-old female, and a 53-year-old female, each of whom met DSM-IV criteria for generalised anxiety disorder (GAD). Each case was a clinical replication of an initial trial of BATA reported in Turner and Leach (2009). Treatment was delivered in twelve weekly 60-minute individual sessions and evaluated using an A-B-C phase change with repeated measurement design. Decreased scores in self-reported anxiety were obtained in each case and the improvements were maintained during a 3-month no treatment maintenance phase. Compared to baseline, each participant also recorded increases in activity levels in some key life areas during the treatment phase. These preliminary findings suggest that increased activation in functionally positive areas is associated with reported decreases in anxiety and that BATA could be an effective stand-alone treatment for GAD in adults
The PL calibration for Milky Way Cepheids and its implications for the distance scale
The rationale behind recent calibrations of the Cepheid PL relation using the
Wesenheit formulation is reviewed and reanalyzed, and it is shown that recent
conclusions regarding a possible change in slope of the PL relation for
short-period and long-period Cepheids are tied to a pathological distribution
of HST calibrators within the instability strip. A recalibration of the
period-luminosity relation is obtained using Galactic Cepheids in open clusters
and groups, the resulting relationship, described by log L/L_sun =
2.415(+-0.035) + 1.148(+-0.044)log P, exhibiting only the moderate scatter
expected from color spread within the instability strip. The relationship is
confirmed by Cepheids with HST parallaxes, although without the need for
Lutz-Kelker corrections, and in general by Cepheids with revised Hipparcos
parallaxes, albeit with concerns about the cited precisions of the latter. A
Wesenheit formulation of Wv = -2.259(+-0.083) - 4.185(+-0.103)log P for
Galactic Cepheids is tested successfully using Cepheids in the inner regions of
the galaxy NGC 4258, confirming the independent geometrical distance
established for the galaxy from OH masers. Differences between the extinction
properties of interstellar and extragalactic dust may yet play an important
role in the further calibration of the Cepheid PL relation and its application
to the extragalactic distance scale.Comment: Accepted for Publication (Astrophysics & Space Science
On the degree of scale invariance of inflationary perturbations
Many, if not most, inflationary models predict the power-law index of the
spectrum of density perturbations is close to one, though not precisely equal
to one, |n-1| \sim O(0.1), implying that the spectrum of density perturbations
is nearly, but not exactly, scale invariant. Some models allow n to be
significantly less than one (n \sim 0.7); a spectral index significantly
greater than one is more difficult to achieve. We show that n \approx 1 is a
consequence of the slow-roll conditions for inflation and ``naturalness,'' and
thus is a generic prediction of inflation. We discuss what is required to
deviate significantly from scale invariance, and then show, by explicit
construction, the existence of smooth potentials that satisfy all the
conditions for successful inflation and give as large as 2.Comment: 7 pages, 2 figures, submitted to Phys. Rev.
Damping of Tensor Modes in Cosmology
An analytic formula is given for the traceless transverse part of the
anisotropic stress tensor due to free streaming neutrinos, and used to derive
an integro-differential equation for the propagation of cosmological
gravitational waves. The solution shows that anisotropic stress reduces the
squared amplitude by 35.6 % for wavelengths that enter the horizon during the
radiation-dominated phase, independent of any cosmological parameters. This
decreases the tensor temperature and polarization correlation functions for
these wavelengths by the same amount. The effect is less for wavelengths that
enter the horizon at later times. At the longest wavelengths the decrease in
the tensor correlation functions due to neutrino free streaming ranges from
10.7% for to 9.0% for . An Appendix gives a
general proof that tensor as well as scalar modes satisfy a conservation law
for perturbations outside the horizon, even when the anisotropic stress tensor
is not negligible.Comment: 14 pages. The original version of this paper has been expanded to
deal with perturbations of any wavelength. While for wavelengths short enough
to enter the horizon during radiation dominance, temperature and polarization
correlations are damped by 35.6%, at the longest wavelengths the damping is
from 9.0% to 11%. An added Appendix gives a general proof that tensor as well
as scalar modes satisfy a conservation law outside the horizon, even during
neutrino decoupling. Some references are also adde
Quasi Two-dimensional Transfer of Elastic Waves
A theory for multiple scattering of elastic waves is presented in a random
medium bounded by two ideal free surfaces, whose horizontal size is infinite
and whose transverse size is smaller than the mean free path of the waves. This
geometry is relevant for seismic wave propagation in the Earth crust. We derive
a time-dependent, quasi-2D radiative transfer equation, that describes the
coupling of the eigenmodes of the layer (surface Rayleigh waves, SH waves, and
Lamb waves). Expressions are found that relate the small-scale fluctuations to
the life time of the modes and to their coupling rates. We discuss a diffusion
approximation that simplifies the mathematics of this model significantly, and
which should apply at large lapse times. Finally, coherent backscattering is
studied within the quasi-2D radiative transfer equation for different source
and detection configurations.Comment: REVTeX, 36 pages with 10 figures. Submitted to Phys. Rev.
Shear and Mixing in Oscillatory Doubly Diffusive Convection
To investigate the mechanism of mixing in oscillatory doubly diffusive (ODD)
convection, we truncate the horizontal modal expansion of the Boussinesq
equations to obtain a simplified model of the process. In the astrophysically
interesting case with low Prandtl number, large-scale shears are generated as
in ordinary thermal convection. The interplay between the shear and the
oscillatory convection produces intermittent overturning of the fluid with
significant mixing. By contrast, in the parameter regime appropriate to sea
water, large-scale flows are not generated by the convection. However, if such
flows are imposed externally, intermittent overturning with enhanced mixing is
observed.Comment: 24 pages, 16 figures, Accepted for publication in Geophysical and
Astrophysical Fluid Dynamic
Bjorken unpolarized and polarized sum rules: comparative analysis of large-N_F expansions
Analytical all-orders results are presented for the one-renormalon-chain
contributions to the Bjorken unpolarized sum rule for the F_1 structure
function of nu N deep-inelastic scattering in the large-N_F limit. The
feasibility of estimating higher order perturbative QCD corrections, by the
process of naive nonabelianization (NNA), is studied, in anticipation of
measurement of this sum rule at a Neutrino Factory. A comparison is made with
similar estimates obtained for the Bjorken polarized sum rule. Application of
the NNA procedure to correlators of quark vector and scalar currents, in the
euclidean region, is compared with recent analytical results for the
O(alpha_s^4 N_F^2) terms.Comment: 9 page
The politics of innovation: why innovations need a godfather
Innovation is closely linked to the development of technology. Hence it is often assumed that when an innovation fails it is the technology that is at fault. While this may be true in many instances, there are occasions when it is not the technology that is at fault, rather, it is managerial and organisational aspects that cause problems and lead to failure. Studies have shown that individuals who take on specific roles can play an important part in avoiding these problems. These roles include the technological gatekeeper, the product champion and the sponsor/coach. In addition to these roles, this paper argues that there is another, namely that of godfather. With this role a highly respected, senior figure within an organisation provides support that is critical in ensuring the project overcomes the hurdles that lie in the path of any major new development. The nature of the godfather role is explored through three case studies. These provide examples of the role and show how it can facilitate the innovation process
Absolute values of the London penetration depth in YBa2Cu3O6+y measured by zero field ESR spectroscopy on Gd doped single crystals
Zero-field electron spin resonance (ESR) of dilute Gd ions substituted for Y
in the cuprate superconductor YBaCuO is used as a novel
technique for measuring the absolute value of the low temperature magnetic
penetration depth . The Gd ESR spectrum of samples with
substitution was obtained with a broadband microwave technique
that measures power absorption bolometrically from 0.5 GHz to 21 GHz. This ESR
spectrum is determined by the crystal field that lifts the level degeneracy of
the spin 7/2 Gd ion and details of this spectrum provide information
concerning oxygen ordering in the samples. The magnetic penetration depth is
obtained by relating the number of Gd ions exposed to the microwave magnetic
field to the frequency-integrated intensity of the observed ESR transitions.
This technique has allowed us to determine precise values of for
screening currents flowing in the three crystallographic orientations (, and ) in samples of GdYBaCuO of three different oxygen contents ( K), ( K) and
( K). The in-plane values are found to depart substantially from the
widely reported relation .Comment: 14 pages, 12 figures; version to appear in PR
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Written evidence [PTC0018]
The long-term impact of the pandemic on towns and cities. UK Parliament
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