2,232 research outputs found
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Integrity static analysis of COTS/SOUP
This paper describes the integrity static analysis approach developed to support the justification of commercial off-the-shelf software (COTS) used in a safety-related system. The static analysis was part of an overall software qualification programme, which also included the work reported in our paper presented at Safecomp 2002. Integrity static analysis focuses on unsafe language constructs and “covert” flows, where one thread can affect the data or control flow of another thread. The analysis addressed two main aspects: the internal integrity of the code (especially for the more critical functions), and the intra-component integrity, checking for covert channels. The analysis process was supported by an aggregation of tools, combined and engineered to support the checks done and to scale as necessary. Integrity static analysis is feasible for industrial scale software, did not require unreasonable resources and we provide data that illustrates its contribution to the software qualification programme
Conceptual design study of a coal gasification combined-cycle powerplant for industrial cogeneration
A conceptual design study was conducted to assess technical feasibility, environmental characteristics, and economics of coal gasification. The feasibility of a coal gasification combined cycle cogeneration powerplant was examined in response to energy needs and to national policy aimed at decreasing dependence on oil and natural gas. The powerplant provides the steam heating and baseload electrical requirements while serving as a prototype for industrial cogeneration and a modular building block for utility applications. The following topics are discussed: (1) screening of candidate gasification, sulfur removal and power conversion components; (2) definition of a reference system; (3) quantification of plant emissions and waste streams; (4) estimates of capital and operating costs; and (5) a procurement and construction schedule. It is concluded that the proposed powerplant is technically feasible and environmentally superior
The Effects of Stacking on the Configurations and Elasticity of Single Stranded Nucleic Acids
Stacking interactions in single stranded nucleic acids give rise to
configurations of an annealed rod-coil multiblock copolymer. Theoretical
analysis identifies the resulting signatures for long homopolynucleotides: A
non monotonous dependence of size on temperature, corresponding effects on
cyclization and a plateau in the extension force law. Explicit numerical
results for poly(dA) and poly(rU) are presented.Comment: 4 pages and 2 figures. Accepted in Phys. Rev. E Rapid Com
Towards Identifying and closing Gaps in Assurance of autonomous Road vehicleS - a collection of Technical Notes Part 1
This report provides an introduction and overview of the Technical Topic Notes (TTNs) produced in the Towards Identifying and closing Gaps in Assurance of autonomous Road vehicleS (Tigars) project. These notes aim to support the development and evaluation of autonomous vehicles. Part 1 addresses: Assurance-overview and issues, Resilience and Safety Requirements, Open Systems Perspective and Formal Verification and Static Analysis of ML Systems. Part 2: Simulation and Dynamic Testing, Defence in Depth and Diversity, Security-Informed Safety Analysis, Standards and Guidelines
Modelling background intensity in Affymetrix Genechips
DNA microarrays are devices that are able, in principle, to detect and
quantify the presence of specific nucleic acid sequences in complex biological
mixtures. The measurement consists in detecting fluorescence signals from
several spots on the microarray surface onto which different probe sequences
are grafted. One of the problems of the data analysis is that the signal
contains a noisy background component due to non-specific binding. This paper
presents a physical model for background estimation in Affymetrix Genechips. It
combines two different approaches. The first is based on the sequence
composition, specifically its sequence dependent hybridization affinity. The
second is based on the strong correlation of intensities from locations which
are the physical neighbors of a specific spot on the chip. Both effects are
incorporated in a background functional which contains 24 free parameters,
fixed by minimization on a training data set. In all data analyzed the sequence
specific parameters, obtained by minimization, are found to strongly correlate
with empirically determined stacking free energies for RNA/DNA hybridization in
solution. Moreover, there is an overall agreement with experimental background
data and we show that the physics-based model proposed in this paper performs
on average better than purely statistical approaches for background
calculations. The model thus provides an interesting alternative method for
background subtraction schemes in Affymetrix Genechips.Comment: 8 pages, 4 figure
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Towards Identifying and closing Gaps in Assurance of autonomous Road vehicleS - a collection of Technical Notes Part 2
This report provides an introduction and overview of the Technical Topic Notes (TTNs) produced in the Towards Identifying and closing Gaps in Assurance of autonomous Road vehicleS (Tigars) project. These notes aim to support the development and evaluation of autonomous vehicles. Part 1 addresses: Assurance-overview and issues, Resilience and Safety Requirements, Open Systems Perspective and Formal Verification and Static Analysis of ML Systems. This report is Part 2 and discusses: Simulation and Dynamic Testing, Defence in Depth and Diversity, Security-Informed Safety Analysis, Standards and Guidelines
Wigner crystal model of counterion induced bundle formation of rod-like polyelectrolytes
A simple electrostatic theory of condensation of rod-like polyelectrolytes
under influence of polyvalent ions is proposed. It is based on the idea that
Manning condensation of ions results in formation of the Wigner crystal on a
background of a bundle of rods. It is shown that, depending on a single
dimensionless parameter, this can be the densely packed three-dimensional
Wigner crystal or the two-dimensional crystal on the rod surfaces. For DNA the
location of charge on the spiral results in a model of the one-dimensional
Wigner crystal. It is also argued that the Wigner crystal idea can be applied
to self-assembly of other polyelectrolytes, for example, colloids and DNA-lipid
complexes.Comment: 4 pages; typos corrected, references adde
Cosmology in a String-Dominated Universe
The string-dominated universe locally resembles an open universe, and fits
dynamical measures of power spectra, cluster abundances, redshift distortions,
lensing constraints, luminosity and angular diameter distance relations and
microwave background observations. We show examples of networks which might
give rise to recent string-domination without requiring any fine-tuned
parameters. We discuss how future observations can distinguish this model from
other cosmologies.Comment: 17 pages including 4 figures, of which one is in colo
Effective affinities in microarray data
In the past couple of years several studies have shown that hybridization in
Affymetrix DNA microarrays can be rather well understood on the basis of simple
models of physical chemistry. In the majority of the cases a Langmuir isotherm
was used to fit experimental data. Although there is a general consensus about
this approach, some discrepancies between different studies are evident. For
instance, some authors have fitted the hybridization affinities from the
microarray fluorescent intensities, while others used affinities obtained from
melting experiments in solution. The former approach yields fitted affinities
that at first sight are only partially consistent with solution values. In this
paper we show that this discrepancy exists only superficially: a sufficiently
complete model provides effective affinities which are fully consistent with
those fitted to experimental data. This link provides new insight on the
relevant processes underlying the functioning of DNA microarrays.Comment: 8 pages, 6 figure
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