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Search Results: 1 - 10 of 1616 matches for " Bjorn Andersson "
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A Real-Time-Enabled, Blackboard-Based, Publish/Subscribe Architecture for Wireless Sensor Nodes  [PDF]
Bjorn Stelte
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.28073
Abstract: Wireless sensor network nodes have only limited resources concerning memory and battery life-time. Mem- ory can be efficiently used by sharing data, and the life-time of a battery can be extended, when the node has long power saving sleep-phases. We propose a publish/subscribe architecture that achieves these two aims. The results of our work are of great interest for sensor application developers, giving them now the opportu- nity to use our architecture for sharing data among different applications on the node as well as the different layers of the operating system. We introduce a blackboard which is used for centrally storing published val- ues, like measured data from a monitored sensor. This makes it possible to share stored data without monitoring the sensors once again, which is advantageously concerning power consumption, memory space, and reaction time. Beside the proposed publish/subscribe method for sensor nodes with its notification possibili- ties, our architecture fulfills also real-time requirements. We show how the well-known sensor operating system MANTIS OS can be extended by a real-time enabled, blackboard-based publish/subscribe architect- ture. This architecture and first of all its implementation is of special interest for cross layer optimization of sensor applications. Cross-layer approaches benefit from our architecture because the available implementa- tion can be used as an efficient framework for central storing and managing of shared values.
Repetitive DNA is associated with centromeric domains in Trypanosoma brucei but not Trypanosoma cruzi
Samson O Obado, Christopher Bot, Daniel Nilsson, Bjorn Andersson, John M Kelly
Genome Biology , 2007, DOI: 10.1186/gb-2007-8-3-r37
Abstract: We report evidence on the location and nature of centromeric DNA in Trypanosoma cruzi and Trypanosoma brucei. In T. cruzi, we used telomere-associated chromosome fragmentation and found that GC-rich transcriptional 'strand-switch' domains composed predominantly of degenerate retrotranposons are a shared feature of regions that confer mitotic stability. Consistent with this, etoposide-mediated topoisomerase-II cleavage, a biochemical marker for active centromeres, is concentrated at these domains. In the 'megabase-sized' chromosomes of T. brucei, topoisomerase-II activity is also focused at single loci that encompass regions between directional gene clusters that contain transposable elements. Unlike T. cruzi, however, these loci also contain arrays of AT-rich repeats stretching over several kilobases. The sites of topoisomerase-II activity on T. brucei chromosome 1 and T. cruzi chromosome 3 are syntenic, suggesting that centromere location has been conserved for more than 200 million years. The T. brucei intermediate and minichromosomes, which lack housekeeping genes, do not exhibit site-specific accumulation of topoisomerase-II, suggesting that segregation of these atypical chromosomes might involve a centromere-independent mechanism.The localization of centromeric DNA in trypanosomes fills a major gap in our understanding of genome organization in these important human pathogens. These data are a significant step towards identifying and functionally characterizing other determinants of centromere function and provide a framework for dissecting the mechanisms of chromosome segregation.Centromeres are the chromosomal loci where kinetochores are assembled. The centromere/kinetochore complex is the anchor for attachment of the microtubule spindles that facilitate segregation. Two main classes of centromere have been identified. In most eukaryotes, centromeres are 'regional' and can encompass large regions of chromosomal DNA, ranging from 0.3-15 Mb in species as divers
DNPTrapper: an assembly editing tool for finishing and analysis of complex repeat regions
Erik Arner, Martti T Tammi, Anh-Nhi Tran, Ellen Kindlund, Bjorn Andersson
BMC Bioinformatics , 2006, DOI: 10.1186/1471-2105-7-155
Abstract: We have developed DNPTrapper, a shotgun sequence finishing tool, specifically designed to address the problems posed by the presence of repeated regions in the target sequence. The program detects and visualizes single base differences between nearly identical repeat copies, and offers the overview and flexibility needed to rapidly resolve complex regions within a working session. The use of a database allows large amounts of data to be stored and handled, and allows viewing of mammalian size genomes. The program is available under an Open Source license.With DNPTrapper, it is possible to separate repeated regions that previously were considered impossible to resolve, and finishing tasks that previously took days or weeks can be resolved within hours or even minutes.High-throughput methods for genome sequencing, in combination with increased computer power and better algorithms for sequence assembly, have yielded a plethora of genomes accessible for analysis. However, complicated parts of sequenced genomes tend to be left unfinished to a large extent. This is especially the case for eukaryotic genomes, where the majority of the genomes presently sequenced have repeated regions that were left unresolved (see e.g. [1] and [2] for discussion on how duplications affect eukaryotic genome projects). Current shotgun sequencing assembly programs are not designed to handle long stretches of repeated DNA in the target sequence, and it is common that repeated sequences are left out of the assembly altogether. In addition, repeats often cause assembly errors, e.g. large artificial rearrangements due to misassembled repeat regions. Also common are assemblies with the repeat copies merged into alignments of high coverage, with reads of the repeat region piled on top of each other. Although many repeats appear to have no discernible biological function, in many cases the repeats play an important role in the biology of the organism [3], and some organisms have a significant amount
Increasing Road Traffic Throughput through Dynamic Traffic Accident Risk Mitigation  [PDF]
Emma Fitzgerald, Bjorn Landfeldt
Journal of Transportation Technologies (JTTs) , 2015, DOI: 10.4236/jtts.2015.54021
Abstract: The introduction of vehicular ad-hoc networks (VANETs) leads to the possibility to re-evaluate many traditional functions and views of road traffic networks. The ability for vehicles and infrastructure to communicate and collaborate will enable many novel solutions for problems as diverse as collision avoidance and traffic management with the view of reducing traffic congestion, increasing the effectiveness of logistics systems etc. In this paper we introduce a novel framework that utilises VANET information to share information about risk factors among road occupants and infrastructure. We introduce the concept of risk limits as a means of traffic accident risk mitigation, whereby vehicles need to adjust their behaviour to maintain a given level of risk. We discuss determination of risk values and detail this process using the NSW traffic accident database. We show how the effects on risk of particular vehicular behaviours such as speed and headway can be calculated and use these results to modify vehicle behaviour in real time to maintain a predefined risk limit. Experiments are carried out using the Paramics Microsimulator. Our results show that it is possible to reduce the accident rate among vehicles while at the same time increasing road network throughput by exploiting the variation in risk between vehicles.
A global initiative for the elimination of avoidable blindness
Thylefors Bjorn
Indian Journal of Ophthalmology , 1998,
Abstract:
Review of Donald Boisvert, Sanctity and Male Desire: A Gay Reading of Saints
Bjorn Krondorfer
Journal of Men, Masculinities and Spirituality , 2007,
Abstract: Review of Donald Boisvert, Sanctity and Male Desire: A Gay Reading of Saints (Cleveland: The Pilgrim Press, 2004), 224 pp.
Review of Kathryn M. Ringrose, The Perfect Servant: Eunuchs and the Social Construction of Gender in Byzantium
Bjorn Krondorfer
Journal of Men, Masculinities and Spirituality , 2007,
Abstract: Review of Kathryn M. Ringrose, The Perfect Servant: Eunuchs and the Social Construction of Gender in Byzantium (Chicago: Chicago University Press, 2003), xiv + 295 pp.
Conditions for negative specific heat in systems of attracting classical particles
Bjorn Einarsson
Physics , 2004, DOI: 10.1016/j.physleta.2004.09.066
Abstract: We identify conditions for the presence of negative specific heat in non-relativistic self-gravitating systems and similar systems of attracting particles. The method used, is to analyse the Virial theorem and two soluble models of systems of attracting particles, and to map the sign of the specific heat for different combinations of the number of spatial dimensions of the system, $D$($\geq 2$), and the exponent, $\nu$($\neq 0$), in the force potential, $\phi=Cr^\nu$. Negative specific heat in such systems is found to be present exactly for $\nu=-1$, at least for $D \geq 3$. For many combinations of $D$ and $\nu$ representing long-range forces, the specific heat is positive or zero, for both models and the Virial theorem. Hence negative specific heat is not caused by long-range forces as such. We also find that negative specific heat appears when $\nu$ is negative, and there is no singular point in a certain density distribution. A possible mechanism behind this is suggested.
The Schroedinger functional for Gross-Neveu models
Bjorn Leder
Physics , 2007,
Abstract: Gross-Neveu type models with a finite number of fermion flavours are studied on a two-dimensional Euclidean space-time lattice. The models are asymptotically free and are invariant under a chiral symmetry. These similarities to QCD make them perfect benchmark systems for fermion actions used in large scale lattice QCD computations. The Schroedinger functional for the Gross-Neveu models is defined for both, Wilson and Ginsparg-Wilson fermions, and shown to be renormalisable in 1-loop lattice perturbation theory. In two dimensions four fermion interactions of the Gross-Neveu models have dimensionless coupling constants. The symmetry properties of the four fermion interaction terms and the relations among them are discussed. For Wilson fermions chiral symmetry is explicitly broken and additional terms must be included in the action. Chiral symmetry is restored up to cut-off effects by tuning the bare mass and one of the couplings. The critical mass and the symmetry restoring coupling are computed to second order in lattice perturbation theory. This result is used in the 1-loop computation of the renormalised couplings and the associated beta-functions. The renormalised couplings are defined in terms of suitable boundary-to-boundary correlation functions. In the computation the known first order coefficients of the beta-functions are reproduced. One of the couplings is found to have a vanishing beta-function. The calculation is repeated for the recently proposed Schroedinger functional with exact chiral symmetry, i.e. Ginsparg-Wilson fermions. The renormalisation pattern is found to be the same as in the Wilson case. Using the regularisation dependent finite part of the renormalised couplings, the ratio of the Lambda-parameters is computed.
Test of the Schr?dinger functional with chiral fermions in the Gross-Neveu model
Bjorn Leder
Physics , 2007, DOI: 10.1088/1126-6708/2008/04/044
Abstract: The recently proposed construction of chiral fermions on lattices with boundaries is tested in an interacting theory up to first order of perturbation theory. We confirm that, in the bulk of the lattice, the chiral Ward identities take their continuum value up to cutoff effects without any tuning. Universal quantities are defined that have an expansion in the renormalised couplings with coefficients that are functions of the physical size and the periodicity in the spatial direction. These coefficient functions have to be identical for different discretisations. We find agreement with the standard Wilson fermions. The computation is done in the asymptotically free Gross-Neveu model with continuous chiral symmetry.
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