39 research outputs found
A Programmable ANSI C Code Transformation Engine.
Source code transformations are a very effective method of parallelizing and improving the efficiency of programs. Unfortunately most compiler systems require implementing separate (sub-)programs for each transformation. This paper describes a different approach. We designed and implemented a fully programmable C code transformation engine. It can be programmed by means of a transformation language. This language was especially designed to be easy to use and flexible enough to express most of the common transformations that can be found in the mainstream compiler systems. In addition, it allows specification of more exotic, but highly desirable, transformations (like for example inter-procedural transformations). The program features a userfriendly graphical user interface, allowing interactive application of transformations. Its possible applications range from coarse-grain parallelism exploitation to optimizers for multimedia instruction sets
A Programmable ANSI C Code Transformation Engine.
Source code transformations are a very effective method of parallelizing and improving the efficiency of programs. Unfortunately most compiler systems require implementing separate (sub-)programs for each transformation. This paper describes a different approach. We designed and implemented a fully programmable C code transformation engine. It can be programmed by means of a transformation language. This language was especially designed to be easy to use and flexible enough to express most of the common transformations that can be found in the mainstream compiler systems. In addition, it allows specification of more exotic, but highly desirable, transformations (like for example inter-procedural transformations). The program features a userfriendly graphical user interface, allowing interactive application of transformations. Its possible applications range from coarse-grain parallelism exploitation to optimizers for multimedia instruction sets
General Relativistic versus Newtonian: a universality in radiation hydrodynamics
We compare Newtonian and general relativistic descriptions of the stationary
accretion of self-gravitating fluids onto compact bodies. Spherical symmetry
and thin gas approximation are assumed. Luminosity depends, amongst other
factors, on the temperature and the contribution of gas to the total mass, in
both -- general relativistic () and Newtonian () -- models. We
discover a remarkable universal behaviour for transonic flows: the ratio of
respective luminosities is independent of the fractional mass of
the gas and depends on asymptotic temperature. It is close to 1 in the regime
of low asymptotic temperatures and can grow by one order of magnitude for high
temperatures. These conclusions are valid for a wide range of polytropic
equations of state.Comment: 8 pages, 4 figure
Numerical investigation of the late-time Kerr tails
The late-time behavior of a scalar field on fixed Kerr background is examined
in a numerical framework incorporating the techniques of conformal
compactification and hyperbolic initial value formulation. The applied code is
1+(1+2) as it is based on the use of the spectral method in the angular
directions while in the time-radial section fourth order finite differencing,
along with the method of lines, is applied. The evolution of various types of
stationary and non-stationary pure multipole initial states are investigated.
The asymptotic decay rates are determined not only in the domain of outer
communication but along the event horizon and at future null infinity as well.
The decay rates are found to be different for stationary and non-stationary
initial data, and they also depend on the fall off properties of the initial
data toward future null infinity. The energy and angular momentum transfers are
found to show significantly different behavior in the initial phase of the time
evolution. The quasinormal ringing phase and the tail phase are also
investigated. In the tail phase, the decay exponents for the energy and angular
momentum losses at future null infinity are found to be smaller than at the
horizon which is in accordance with the behavior of the field itself and it
means that at late times the energy and angular momentum falling into the black
hole become negligible in comparison with the energy and angular momentum
radiated toward future null infinity. The energy and angular momentum balances
are used as additional verifications of the reliability of our numerical
method.Comment: 33 pages, 12 figure
Functional Requirements for Assistive Technology for People with Cognitive Impairments and Dementia
The amount of technological aids on the market to support people in their everyday functioning is increasing. For example mobile telephone, electronic diary, skyping and domotics. Many of these aids are too complicated to operate for people with cognitive impairments, like dementia. For technology to be practicable and useful for them, it will have to meet certain requirements. This paper addresses the needs and impairments of people with dementia, and the functional requirements for assistive technology for people with dementia. © 2012 Springer-Verlag
Generalized inverse mean curvature flows in spacetime
Motivated by the conjectured Penrose inequality and by the work of Hawking,
Geroch, Huisken and Ilmanen in the null and the Riemannian case, we examine
necessary conditions on flows of two-surfaces in spacetime under which the
Hawking quasilocal mass is monotone. We focus on a subclass of such flows which
we call uniformly expanding, which can be considered for null as well as for
spacelike directions. In the null case, local existence of the flow is
guaranteed. In the spacelike case, the uniformly expanding condition leaves a
1-parameter freedom, but for the whole family, the embedding functions satisfy
a forward-backward parabolic system for which local existence does not hold in
general. Nevertheless, we have obtained a generalization of the weak
(distributional) formulation of this class of flows, generalizing the
corresponding step of Huisken and Ilmanen's proof of the Riemannian Penrose
inequality.Comment: 21 pages, 1 figur
From Geometry to Numerics: interdisciplinary aspects in mathematical and numerical relativity
This article reviews some aspects in the current relationship between
mathematical and numerical General Relativity. Focus is placed on the
description of isolated systems, with a particular emphasis on recent
developments in the study of black holes. Ideas concerning asymptotic flatness,
the initial value problem, the constraint equations, evolution formalisms,
geometric inequalities and quasi-local black hole horizons are discussed on the
light of the interaction between numerical and mathematical relativists.Comment: Topical review commissioned by Classical and Quantum Gravity.
Discussion inspired by the workshop "From Geometry to Numerics" (Paris, 20-24
November, 2006), part of the "General Relativity Trimester" at the Institut
Henri Poincare (Fall 2006). Comments and references added. Typos corrected.
Submitted to Classical and Quantum Gravit
A common genetic network underlies substance use disorders and disruptive or externalizing disorders
Here we summarize evidence obtained by our group during the last two decades, and contrasted it with a review of related data from the available literature to show that behavioral syndromes involving attention deficit/hyperactivity disorder (ADHD), externalizing disorders, and substance-use disorder (SUD) share similar signs and symptoms (i.e., have a biological basis as common syndromes), physiopathological and psychopathological mechanisms, and genetic factors. Furthermore, we will show that the same genetic variants harbored in different genes are associated with different syndromes and that non-linear interactions between genetic variants (epistasis) best explain phenotype severity, long-term outcome, and response to treatment. These data have been depicted in our studies by extended pedigrees, where ADHD, externalizing symptoms, and SUD segregate and co-segregate. Finally, we applied here a new formal network analysis using the set of significantly replicated genes that have been shown to be either associated and/or linked to ADHD, disruptive behaviors, and SUD in order to detect significantly enriched gene categories for protein and genetic interactions, pathways, co-expression, co-localization, and protein domain similarity. We found that networks related to pathways involved in axon guidance, regulation of synaptic transmission, and regulation of transmission of nerve impulse are overrepresented. In summary, we provide compiled evidence of complex networks of genotypes underlying a wide phenotype that involves SUD and externalizing disorders
Performance Driven Synthesis of Digital Systems
Electrical Engineering, Mathematics and Computer Scienc