Time and frequency stability for the Crustal Dynamics Project

Very long base interferometry (VLBI) and laser ranging to artificial satellites and the Moon were used to determined vector baselines between stations with precisions of about one part in 10 to the 8th power. Deformations and strain accumulations in active earthquake regions were determined by making frequent measurements of baselines between many stations in active areas near plate boundaries

Experimental discrimination of geminate and non-geminate recombination in a-Si:H

Journal ArticleA study of charge-carrier recombination in intrinsic hydrogenated amorphous silicon (a-Si:H) is presented using pulsed electrically and pulsed optically detected magnetic-resonance spectroscopies in order to measure the influence of spin-dependent recombination on photoluminescence (PL) and photoconductivity (PC). The experiments show band tail state recombination influencing the PL but not the PC which constitutes geminate recombination of correlated charge carriers that do not contribute to charge transport. In contrast, nongeminate recombination through silicon dangling bonds is observed influencing both PL and PC. The experiments presented constitute a direct and unambiguous observation of geminate and nongeminate recombination in a-Si:H

An a priori model for the reduction of nutation observations: KSV(1994.3) nutation series

We discuss the formulation of a new nutation series to be used in the reduction of modern space geodetic data. The motivation for developing such a series is to develop a nutation series that has smaller short period errors than the IAU 1980 nutation series and to provide a series that can be used with techniques such as the Global Positioning System (GPS) that have sensitivity to nutations but can directly separate the effects of nutations from errors in the dynamical force models that effect the satellite orbits. A modern nutation series should allow the errors in the force models for GPS to be better understood. The series is constructed by convolving the Kinoshita and Souchay rigid Earth nutation series with an Earth response function whose parameters are partly based on geophysical models of the Earth and partly estimated from a long series (1979-1993) of very long baseline interferometry (VLBI) estimates of nutation angles. Secular rates of change of the nutation angles to represent corrections to the precession constant and a secular change of the obliquity of the ecliptic are included in the theory. Time dependent amplitudes of the Free Core Nutation (FCN) that is most likely excited by variations in atmospheric pressure are included when the geophysical parameters are estimated. The complex components of the prograde annual nutation are estimated simultaneously with the geophysical parameters because of the large contribution to the nutation from the S(sub 1) atmospheric tide. The weighted root mean square (WRMS) scatter of the nutation angle estimates about this new model are 0.32 mas and the largest correction to the series when the amplitudes of the ten largest nutations are estimated is 0.18 +/- 0.03 mas for the in phase component of the prograde 18. 6 year nutation

Delivering information and brief advice on alcohol (IBA) in social work and social care settings: an exploratory study

Social workers and practitioners working in social care are potentially key players in the prevention of alcohol-related harm and harm reduction for people using services and their carers. This requires attention to workforce development alongside the selection of appropriate tools to support prevention strategies. We report findings from a UK exploratory study into the potential of using Identification and Brief Advice (IBA) as a tool for screening and prevention in social work and social care settings. Thirty-six social workers and social care practitioners attended one of two training workshops on IBA in the South East of England. Pre and post-workshop surveys (n = 35 and n = 20, respectively) and four post-workshop focus groups (n = 36) were conducted with participants to explore the application of IBA taking into account the paradigmatic shift towards prevention and holistic approaches indicated in recent UK legislation and policy. Four themes emerged from the findings: (1) perceptions of the social work/social care role in responding to alcohol problems, (2) ethical concerns, (3) time conflicts and problems of delivering IBA and (4) the role of training. Further studies are needed to evaluate the effectiveness of motivational techniques and tools that social workers can use to promote preventative practise for alcohol-related harm. Different strategies are required to engage and support those working in social care to increase proactive engagement with problematic alcohol use in everyday practise settings

Empiric Models of the Earth's Free Core Nutation

Free core nutation (FCN) is the main factor that limits the accuracy of the modeling of the motion of Earth's rotational axis in the celestial coordinate system. Several FCN models have been proposed. A comparative analysis is made of the known models including the model proposed by the author. The use of the FCN model is shown to substantially increase the accuracy of the modeling of Earth's rotation. Furthermore, the FCN component extracted from the observed motion of Earth's rotational axis is an important source for the study of the shape and rotation of the Earth's core. A comparison of different FCN models has shown that the proposed model is better than other models if used to extract the geophysical signal (the amplitude and phase of FCN) from observational data.Comment: 8 pages, 3 figures; minor update of the journal published versio