Moving body velocity arresting line

The arresting of a moving body is improved through the use of steel cables that elongate to absorb the kinetic energy of the body. A sleeve surrounds the cables, protecting them from chafing and providing a failsafe energy absorbing system should the cables fail

An introduction to the new Productivity Information Management System (PIMS)

The productivity information management system (PIMS), is described. The main objective of this computerized system is to enable management scientists to interactively explore data concerning DSN operations, maintenance and repairs, to develop and verify models for management planning. The PIMS will provide a powerful set of tools for iteratively manipulating data sets in a wide variety of ways. The initial version of PIMS will be a small scale pilot system. The following topics are discussed: (1) the motivation for developing PIMS; (2) various data sets which will be integrated by PIMS; (3) overall design of PIMS; and (4) how PIMS will be used. A survey of relevant databases concerning DSN operations at Goldstone is also included

D-branes and the Noncommutative Torus

We show that in certain superstring compactifications, gauge theories on noncommutative tori will naturally appear as D-brane world-volume theories. This gives strong evidence that they are well-defined quantum theories. It also gives a physical derivation of the identification proposed by Connes, Douglas and Schwarz of Matrix theory compactification on the noncommutative torus with M theory compactification with constant background three-form tensor field.Comment: harvmac, 5 pp. Minor error fixe

Worldvolume Theories, Holography, Duality and Time

Duality transformations involving compactifications on timelike as well as spacelike circles link M-theory, the 10+1-dimensional strong coupling limit of IIA string theory, to other 11-dimensional theories in signatures 9+2 and 6+5 and to type II string theories in all 10-dimensional signatures. These theories have BPS branes of various world-volume signatures, and here we construct the world-volume theories for these branes, which in each case have 16 supersymmetries. For the generalised D-branes of the various type II string theories, these are always supersymmetric Yang-Mills theories with 16 supersymmetries, and we show that these all arise from compactifications of the supersymmetric Yang-Mills theories in 9+1 or 5+5 dimensions. We discuss the geometry of the brane solutions and, for the cases in which the world-volume theories are superconformally invariant, we propose holographically dual string or M theories in constant curvature backgrounds. For product space solutions $X\times Y$, there is in general a conformal field theory associated with the boundary of $X$ and another with the boundary of $Y$.Comment: 35 pages, harvma

New Gauged N=8, D=4 Supergravities

New gaugings of four dimensional N=8 supergravity are constructed, including one which has a Minkowski space vacuum that preserves N=2 supersymmetry and in which the gauge group is broken to $SU(3)xU(1)^2$. Previous gaugings used the form of the ungauged action which is invariant under a rigid $SL(8,R)$ symmetry and promoted a 28-dimensional subgroup ($SO(8),SO(p,8-p)$ or the non-semi-simple contraction $CSO(p,q,8-p-q)$) to a local gauge group. Here, a dual form of the ungauged action is used which is invariant under $SU^*(8)$ instead of $SL(8,R)$ and new theories are obtained by gauging 28-dimensional subgroups of $SU^*(8)$. The gauge groups are non-semi-simple and are different real forms of the $CSO(2p,8-2p)$ groups, denoted $CSO^*(2p,8-2p)$, and the new theories have a rigid SU(2) symmetry. The five dimensional gauged N=8 supergravities are dimensionally reduced to D=4. The $D=5,SO(p,6-p)$ gauge theories reduce, after a duality transformation, to the $D=4,CSO(p,6-p,2)$ gauging while the $SO^*(6)$ gauge theory reduces to the $D=4, CSO^*(6,2)$ gauge theory. The new theories are related to the old ones via an analytic continuation. The non-semi-simple gaugings can be dualised to forms with different gauge groups.Comment: 33 pages. Reference adde

This Girl Can: An Ecological Approach to Investigating Physical Activity in Urban Females

Despite the widely documented physical, psychological and social benefits associated with physical activity, 86% of young females in the UK are insufficiently active (Sport England 2018). In order to improve physical activity levels among young females aged 14-25 in the London Borough of Lambeth, the local council partnered with five physical activity providers and our research team. Together we embarked on the This Girl Can Lambeth project which was inspired by the national campaign This Girl Can. Our role in the project was to evaluate its implementation and outcomes, and additionally to identify barriers and facilitators to participation for this population. We wanted to capture the intrapersonal and interpersonal factors that are often described in literature, but also the relevant environmental, organisational and legislative factors, therefore we used an ecological framework to guide our research. A systematic review of literature showed that the majority of interventions aimed at young females take place in educational settings and focus on either physiological or psychological intrapersonal factors. In an intervention study we compared a physical education program with a school-based intervention program, to investigate its effects on the behaviour and health of young females. Although the intervention program included multi-sports, and encouraged the building of rapport and a foundation for sustained participation in community-based exit routes, we found no clear benefit of the intervention program over physical education. In subsequent qualitative studies we investigated what was amiss. We conducted focus groups with young females who had participated in the intervention programs to understand what factors they perceived to influence their participation. The focus groups highlighted organisational and environmental factors as primary barriers to physical activity. Such factors are stable features of their lives making them difficult barriers to overcome. However, when we interviewed the physical activity providers, the barriers to participation that they perceived were quite different. They identified intrapersonal factors such as self-efficacy and body image as the main barriers to participation. The physical activity providers also discussed the influence of organisational, environmental and legislative factors. The findings from this project can inform interventions, research and policy to ensure Girls indeed Can

Flux Compactifications of M-Theory on Twisted Tori

We find the bosonic sector of the gauged supergravities that are obtained from 11-dimensional supergravity by Scherk-Schwarz dimensional reduction with flux to any dimension D. We show that, if certain obstructions are absent, the Scherk-Schwarz ansatz for a finite set of D-dimensional fields can be extended to a full compactification of M-theory, including an infinite tower of Kaluza-Klein fields. The internal space is obtained from a group manifold (which may be non-compact) by a discrete identification. We discuss the symmetry algebra and the symmetry breaking patterns and illustrate these with particular examples. We discuss the action of U-duality on these theories in terms of symmetries of the D-dimensional supergravity, and argue that in general it will take geometric flux compactifications to M-theory on non-geometric backgrounds, such as U-folds with U-duality transition functions.Comment: Latex, 47 page

Ultrasonic ranking of toughness of tungsten carbide

The feasibility of using ultrasonic attenuation measurements to rank tungsten carbide alloys according to their fracture toughness was demonstrated. Six samples of cobalt-cemented tungsten carbide (WC-Co) were examined. These varied in cobalt content from approximately 2 to 16 weight percent. The toughness generally increased with increasing cobalt content. Toughness was first determined by the Palmqvist and short rod fracture toughness tests. Subsequently, ultrasonic attenuation measurements were correlated with both these mechanical test methods. It is shown that there is a strong increase in ultrasonic attenuation corresponding to increased toughness of the WC-Co alloys. A correlation between attenuation and toughness exists for a wide range of ultrasonic frequencies. However, the best correlation for the WC-Co alloys occurs when the attenuation coefficient measured in the vicinity of 100 megahertz is compared with toughness as determined by the Palmqvist technique

Generalised Geometry for M-Theory

Generalised geometry studies structures on a d-dimensional manifold with a metric and 2-form gauge field on which there is a natural action of the group SO(d,d). This is generalised to d-dimensional manifolds with a metric and 3-form gauge field on which there is a natural action of the group $E_{d}$. This provides a framework for the discussion of M-theory solutions with flux. A different generalisation is to d-dimensional manifolds with a metric, 2-form gauge field and a set of p-forms for $p$ either odd or even on which there is a natural action of the group $E_{d+1}$. This is useful for type IIA or IIB string solutions with flux. Further generalisations give extended tangent bundles and extended spin bundles relevant for non-geometric backgrounds. Special structures that arise for supersymmetric backgrounds are discussed.Comment: 31 page