301 research outputs found
System-focused risk identification and assessment for disaster preparedness: Dynamic threat analysis
AbstractCurrent approaches to risk management stress the need for dynamic (i.e. continuous, ongoing) approaches to risk identification as part of a planned resource application aimed at reducing the expected consequences of undesired outcomes for the object of the assessment. We contend that these approaches place insufficient emphasis on the system knowledge available to the assessor, particularly in respect of three factors, namely the dynamic behavior of the system under threat, the role of human agents and the knowledge availability to those agents.In this paper we address the first of these shortcomings, namely the mobilization of explicit system knowledge in the identification of risks. We present a procedure for mobilizing quantitative and qualitative dynamic system knowledge using the case of flood threat to an electricity substation as a worked example. We assert that the approach described offers the potential of improving risk cognition by mobilizing system knowledge
Advanced technologies for future ground-based, laser-interferometric gravitational wave detectors
We present a review of modern optical techniques being used and developed for the field of gravitational wave detection. We describe the current state-of-the-art of gravitational waves detector technologies with regard to optical layouts, suspensions and test masses. We discuss the dominant sources and noise in each of these subsystems and the developments that will help mitigate them for future generations of detectors. We very briefly summarise some of the novel astrophysics that will be possible with these upgraded detectors
Discussing Quantum Aspects of Higher-Derivative 3D-Gravity in the First-Order Formalism
In this paper, we reassess the issue of deriving the propagators and
identifying the spectrum of excitations associated to the vielbein and spin
connection of (1+2)-D gravity in the presence of dynamical torsion, while
working in the first-order formulation. A number of peculiarities is pointed
out whenever the Chern-Simons term is taken into account along with a
combination of bilinear terms in the torsion tensor. We present a procedure to
derive the full set of propagators, based on an algebra of enlarged spin-type
operators, and we discuss under which conditions the poles of the tree-level
2-point functions correspond to physical excitations that do not conflict with
causality and unitarity
Torsion action and its possible observables
The methods of effective field theory are used to explore the theoretical and
phenomenological aspects of the torsion field. Spinor action coupled to
electromagnetic field and torsion possesses an additional softly broken gauge
symmetry. This symmetry enables one to derive the unique form of the torsion
action compatible with unitarity and renormalizability. It turns out that the
antisymmetric torsion field is equivalent to an massive axial vector field. The
introduction of scalars leads to serious problems which are revealed after the
calculation of the leading two-loop divergences. Thus the phenomenological
aspects of torsion may be studied only for the fermion-torsion systems. In this
part of the paper we obtain an upper bounds for the torsion parameters using
present experimental data on forward-backward Z-pole asymmetries, data on the
experimental limits on four-fermion contact interaction (LEP, HERA, SLAC, SLD,
CCFR) and also TEVATRON limits on the cross section of new gauge boson, which
could be produced as a resonance at high energy collisions. The
present experimental data enable one to put the limits on torsion parameters
for the various range of the torsion mass. We emphasize that for the torsion
mass of the order of the Planck mass no any independent theory for torsion is
possible, and one must directly use string theory.Comment: 24 pages, LaTex, 5 figure
Managing to lead in private enterprise in China: Work values, demography and the development of trust
Previous work on trust has focused on employee trust in management. However, issues of how leaders develop trust in their followers in leader-member exchange (LMX) are under-explored. Based on theories of leader-member exchange, attribution and industrial convergence, this study investigates how the work values of leaders influence the development of their trust in followers and how this is moderated by demographic factors. A survey of 219 leaders was conducted in privately owned enterprises in China. The findings suggest that the work value of centralization is negatively related to leader trust in follower predictability. Group orientation and formalization are positively related to the development of trust in follower good faith. Moreover, age and level of formal education are found to moderate significantly the relationships between leader work values and development of their trust in followers within the context of China. Copyright © 2007 SAGE Publications
Detector Description and Performance for the First Coincidence Observations between LIGO and GEO
For 17 days in August and September 2002, the LIGO and GEO interferometer
gravitational wave detectors were operated in coincidence to produce their
first data for scientific analysis. Although the detectors were still far from
their design sensitivity levels, the data can be used to place better upper
limits on the flux of gravitational waves incident on the earth than previous
direct measurements. This paper describes the instruments and the data in some
detail, as a companion to analysis papers based on the first data.Comment: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial
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Density functional theory based screening of ternary alkali-transition metal borohydrides: A computational material design project
The dissociation of molecules, even the most simple hydrogen molecule, cannot be described accurately within density functional theory because none of the currently available functionals accounts for strong on-site correlation. This problem led to a discussion of properties that the local Kohn-Sham potential has to satisfy in order to correctly describe strongly correlated systems. We derive an analytic expression for the nontrivial form of the Kohn-Sham potential in between the two fragments for the dissociation of a single bond. We show that the numerical calculations for a one-dimensional two-electron model system indeed approach and reach this limit. It is shown that the functional form of the potential is universal, i.e., independent of the details of the two fragments.We acknowledge funding by the Spanish MEC (Grant No. FIS2007-65702-C02-01), “Grupos Consolidados UPV/EHU del Gobierno Vasco” (Grant No. IT-319-07), and the European Community through e-I3 ETSF project (Grant Agreement No. 211956).Peer reviewe
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