13,583 research outputs found
Parallel Sort-Based Matching for Data Distribution Management on Shared-Memory Multiprocessors
In this paper we consider the problem of identifying intersections between
two sets of d-dimensional axis-parallel rectangles. This is a common problem
that arises in many agent-based simulation studies, and is of central
importance in the context of High Level Architecture (HLA), where it is at the
core of the Data Distribution Management (DDM) service. Several realizations of
the DDM service have been proposed; however, many of them are either
inefficient or inherently sequential. These are serious limitations since
multicore processors are now ubiquitous, and DDM algorithms -- being
CPU-intensive -- could benefit from additional computing power. We propose a
parallel version of the Sort-Based Matching algorithm for shared-memory
multiprocessors. Sort-Based Matching is one of the most efficient serial
algorithms for the DDM problem, but is quite difficult to parallelize due to
data dependencies. We describe the algorithm and compute its asymptotic running
time; we complete the analysis by assessing its performance and scalability
through extensive experiments on two commodity multicore systems based on a
dual socket Intel Xeon processor, and a single socket Intel Core i7 processor.Comment: Proceedings of the 21-th ACM/IEEE International Symposium on
Distributed Simulation and Real Time Applications (DS-RT 2017). Best Paper
Award @DS-RT 201
Part-to-whole Registration of Histology and MRI using Shape Elements
Image registration between histology and magnetic resonance imaging (MRI) is
a challenging task due to differences in structural content and contrast. Too
thick and wide specimens cannot be processed all at once and must be cut into
smaller pieces. This dramatically increases the complexity of the problem,
since each piece should be individually and manually pre-aligned. To the best
of our knowledge, no automatic method can reliably locate such piece of tissue
within its respective whole in the MRI slice, and align it without any prior
information. We propose here a novel automatic approach to the joint problem of
multimodal registration between histology and MRI, when only a fraction of
tissue is available from histology. The approach relies on the representation
of images using their level lines so as to reach contrast invariance. Shape
elements obtained via the extraction of bitangents are encoded in a
projective-invariant manner, which permits the identification of common pieces
of curves between two images. We evaluated the approach on human brain
histology and compared resulting alignments against manually annotated ground
truths. Considering the complexity of the brain folding patterns, preliminary
results are promising and suggest the use of characteristic and meaningful
shape elements for improved robustness and efficiency.Comment: Paper accepted at ICCV Workshop (Bio-Image Computing
Discretization of Planar Geometric Cover Problems
We consider discretization of the 'geometric cover problem' in the plane:
Given a set of points in the plane and a compact planar object ,
find a minimum cardinality collection of planar translates of such that
the union of the translates in the collection contains all the points in .
We show that the geometric cover problem can be converted to a form of the
geometric set cover, which has a given finite-size collection of translates
rather than the infinite continuous solution space of the former. We propose a
reduced finite solution space that consists of distinct canonical translates
and present polynomial algorithms to find the reduce solution space for disks,
convex/non-convex polygons (including holes), and planar objects consisting of
finite Jordan curves.Comment: 16 pages, 5 figure
Creative Nonfiction in Social Science: Towards More Engaging and Engaged Research
The paper aims at identifying, explaining and illustrating the affordances of “creative nonfiction” as a style of writing social science. The first part introduces creative nonfiction as a method of writing which brings together empirical material and fiction. In the second part, based on illustrations from my ethnographic research of European “crisis reporters,” written in the form of a novel about a fictional journalist, but also based on a review of existing social science research that employs a creative method of writing, I identify several main affordances of creative nonfiction in social-scientific research. In particular, I argue that creative nonfiction allows scientists to illustrate their findings, to express them in an allegorical way, to organize data into a narrative, to let their pieces of research act in the social world, and to permeate research accounts with self-reflexive moments. I also discuss some apparent negative affordances: challenges that creative nonfiction poses to readers and to the institutionalized academic discourse. Finally, I suggest that writing about sociological problems in the style of creative nonfiction can help to produce more engaging and engaged texts, and I discuss the ethical implications of the approach
Microglial activation arises after aggregation of phosphorylated-tau in a neuron-specific P301S tauopathy mouse model
Alzheimer's disease, progressive supranuclear palsy and frontotemporal dementia are characterized by neuronal expression of aberrant tau protein, tau hyperphosphorylation (pTAU), tau aggregation and neurofibrillary tangle formation sequentially culminating into neuronal cell death, a process termed tauopathy. Our aim was to address at which tauopathy stage neuroinflammation starts and to study the related microglial phenotype. We used Thy1-hTau.P301S (PS) mice expressing human tau with a P301S mutation specifically in neurons. Significant levels of cortical pTAU were present from 2 months onwards. Dystrophic morphological complexity of cortical microglia arose after pTAU accumulation concomitant with increased microglial lysosomal volumes and a significant loss of homeostatic marker Tmem119. Interestingly, we detected increases in neuronal pTAU and postsynaptic structures in the lysosomes of PS microglia. Moreover, the overall cortical postsynaptic density was decreased in 6-month-old PS mice. Together, our results indicate that microglia adopt a pTAU-associated phenotype, and are morphologically and functionally distinct from wild-type microglia after neuronal pTAU accumulation has initiated
Building Information Modeling (BIM) Application for a Section of Bologna’s Red Tramway Line
New technologies such as the I-BIM (Infrastructure Building Information Modeling) are
radically changing the infrastructure design and construction sector. In this study, the I-BIMapproach
has been used for the design of a portion of the future Bologna’s Red Tramway Line. Starting from
the topographical survey of the area, a “federated” model was created, aggregating in a single digital
environment all the models inherent to the individual disciplines involved. Interference analysis (Clash
Detection) between the various disciplines was performed, subject to the preparation of a coordination
matrix and the temporal simulation of the worksite phases (BIM4D). The results have shown that the
I-BIMapproach represents a powerful tool for optimizing and validating infrastructure design, allowing
users to see how the infrastructure integrates and fits into the real 3D environmental context
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