7,608 research outputs found
ECDIS: A European Perspective
This article reviews the European requirements connected with the implementation of ECDIS. It is a slightly modified version of a report prepared for an action on ECDIS and maritime transport launched in February 1994 within the framework of the European cooperation in the field of Scientific and Technical research (COST 326), under the aegis of the Directorate General for Transport of the European Commission
Construction of SU(3) irreps in canonical SO(3)-coupled bases
Alternative canonical methods for defining canonical SO(3)-coupled bases for
SU(3) irreps are considered and compared. It is shown that a basis that
diagonalizes a particular linear combination of SO(3) invariants in the SU(3)
universal enveloping algebra gives basis states that have good quantum
numbers in the asymptotic rotor-model limit.Comment: no figure
Neutron-Proton Correlations in an Exactly Solvable Model
We examine isovector and isoscalar neutron-proton correlations in an exactly
solvable model based on the algebra SO(8). We look particularly closely at
Gamow-Teller strength and double beta decay, both to isolate the effects of the
two kinds of pairing and to test two approximation schemes: the renormalized
neutron-proton QRPA (RQRPA) and generalized BCS theory. When isoscalar pairing
correlations become strong enough a phase transition occurs and the dependence
of the Gamow-Teller beta+ strength on isospin changes in a dramatic and
unfamiliar way, actually increasing as neutrons are added to an N=Z core.
Renormalization eliminates the well-known instabilities that plague the QRPA as
the phase transition is approached, but only by unnaturally suppressing the
isoscalar correlations. Generalized BCS theory, on the other hand, reproduces
the Gamow-Teller strength more accurately in the isoscalar phase than in the
usual isovector phase, even though its predictions for energies are equally
good everywhere. It also mixes T=0 and T=1 pairing, but only on the isoscalar
side of the phase transition.Comment: 13 pages + 11 postscript figures, in RevTe
Apparatus to control and visualize the impact of a high-energy laser pulse on a liquid target
We present an experimental apparatus to control and visualize the response of
a liquid target to a laser-induced vaporization. We use a millimeter-sized drop
as target and present two liquid-dye solutions that allow a variation of the
absorption coefficient of the laser light in the drop by seven orders of
magnitude. The excitation source is a Q-switched Nd:YAG laser at its
frequency-doubled wavelength emitting nanosecond pulses with energy densities
above the local vaporization threshold. The absorption of the laser energy
leads to a large-scale liquid motion at timescales that are separated by
several orders of magnitude, which we spatiotemporally resolve by a combination
of ultra-high-speed and stroboscopic high-resolution imaging in two orthogonal
views. Surprisingly, the large-scale liquid motion at upon laser impact is
completely controlled by the spatial energy distribution obtained by a precise
beam-shaping technique. The apparatus demonstrates the potential for accurate
and quantitative studies of laser-matter interactions.Comment: Submitted to Review of Scientific Instrument
String amplitudes in arbitrary dimensions
We calculate gravitational dressed tachyon correlators in non critcal
dimensions. The 2D gravity part of our theory is constrained to constant
curvature. Then scaling dimensions of gravitational dressed vertex operators
are equal to their bare conformal dimensions. Considering the model as d+2
dimensional critical string we calculate poles of generalized Shapiro-Virasoro
amplitudes.Comment: 14 page
Photoelastic force measurements in granular materials
Photoelastic techniques are used to make both qualitative and quantitative
measurements of the forces within idealized granular materials. The method is
based on placing a birefringent granular material between a pair of polarizing
filters, so that each region of the material rotates the polarization of light
according to the amount of local of stress. In this review paper, we summarize
past work using the technique, describe the optics underlying the technique,
and illustrate how it can be used to quantitatively determine the vector
contact forces between particles in a 2D granular system. We provide a
description of software resources available to perform this task, as well as
key techniques and resources for building an experimental apparatus
Mixed-method study of a conceptual model of evidence-based intervention sustainment across multiple public-sector service settings.
BackgroundThis study examines sustainment of an EBI implemented in 11 United States service systems across two states, and delivered in 87 counties. The aims are to 1) determine the impact of state and county policies and contracting on EBI provision and sustainment; 2) investigate the role of public, private, and academic relationships and collaboration in long-term EBI sustainment; 3) assess organizational and provider factors that affect EBI reach/penetration, fidelity, and organizational sustainment climate; and 4) integrate findings through a collaborative process involving the investigative team, consultants, and system and community-based organization (CBO) stakeholders in order to further develop and refine a conceptual model of sustainment to guide future research and provide a resource for service systems to prepare for sustainment as the ultimate goal of the implementation process.MethodsA mixed-method prospective and retrospective design will be used. Semi-structured individual and group interviews will be used to collect information regarding influences on EBI sustainment including policies, attitudes, and practices; organizational factors and external policies affecting model implementation; involvement of or collaboration with other stakeholders; and outer- and inner-contextual supports that facilitate ongoing EBI sustainment. Document review (e.g., legislation, executive orders, regulations, monitoring data, annual reports, agendas and meeting minutes) will be used to examine the roles of state, county, and local policies in EBI sustainment. Quantitative measures will be collected via administrative data and web surveys to assess EBI reach/penetration, staff turnover, EBI model fidelity, organizational culture and climate, work attitudes, implementation leadership, sustainment climate, attitudes toward EBIs, program sustainment, and level of institutionalization. Hierarchical linear modeling will be used for quantitative analyses. Qualitative analyses will be tailored to each of the qualitative methods (e.g., document review, interviews). Qualitative and quantitative approaches will be integrated through an inclusive process that values stakeholder perspectives.DiscussionThe study of sustainment is critical to capitalizing on and benefiting from the time and fiscal investments in EBI implementation. Sustainment is also critical to realizing broad public health impact of EBI implementation. The present study takes a comprehensive mixed-method approach to understanding sustainment and refining a conceptual model of sustainment
Solvent content of protein crystals from diffraction intensities by Independent Component Analysis
An analysis of the protein content of several crystal forms of proteins has
been performed. We apply a new numerical technique, the Independent Component
Analysis (ICA), to determine the volume fraction of the asymmetric unit
occupied by the protein. This technique requires only the crystallographic data
of structure factors as input.Comment: 9 pages, 2 figures, 1 tabl
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Verification and validation guidelines for high integrity systems. Volume 1
High integrity systems include all protective (safety and mitigation) systems for nuclear power plants, and also systems for which comparable reliability requirements exist in other fields, such as in the process industries, in air traffic control, and in patient monitoring and other medical systems. Verification aims at determining that each stage in the software development completely and correctly implements requirements that were established in a preceding phase, while validation determines that the overall performance of a computer system completely and correctly meets system requirements. Volume I of the report reviews existing classifications for high integrity systems and for the types of errors that may be encountered, and makes recommendations for verification and validation procedures, based on assumptions about the environment in which these procedures will be conducted. The final chapter of Volume I deals with a framework for standards in this field. Volume II contains appendices dealing with specific methodologies for system classification, for dependability evaluation, and for two software tools that can automate otherwise very labor intensive verification and validation activities
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