449 research outputs found
Fast modularisation and aomic decomposition of ontologies using axiom dependency hypergraphs
In this paper we define the notion of an axiom dependency hypergraph, which explicitly represents how axioms are included into a module by the algorithm for computing locality-based modules. A locality-based module of an ontology corresponds to a set of connected nodes in the hypergraph, and atoms of an ontology to strongly connected components. Collapsing the strongly connected components into single nodes yields a condensed hypergraph that comprises a representation of the atomic decomposition of the ontology. To speed up the condensation of the hypergraph, we first reduce its size by collapsing the strongly connected components of its graph fragment employing a linear time graph algorithm. This approach helps to significantly reduce the time needed for computing the atomic decomposition of an ontology. We provide an experimental evaluation for computing the atomic decomposition of large biomedical ontologies. We also demonstrate a significant improvement in the time needed to extract locality-based modules from an axiom dependency hypergraph and its condensed version
The non-sagittal knee moment vector identifies "at risk" individuals that the knee abduction moment alone does not
Multi-planar forces and moments are known to injure the anterior cruciate ligament (ACL). In ACL injury risk studies however, the uni-planar frontal plane external knee abduction moment is frequently studied in isolation. This study aimed to determine if the frontal plane knee moment (KM-Y) could classify all individuals crossing a risk threshold compared to those classified by a multi-planar non-sagittal knee moment vector (KM-YZ). Recreationally active females completed three sports tasks - drop vertical jumps, single-leg drop vertical jumps and planned sidesteps. Peak knee abduction moments and peak non-sagittal resultant knee moments were obtained for each task and a risk threshold of the sample mean plus 1.6 standard deviations was used for classification. A sensitivity analysis of the threshold from 1-2 standard deviations was also conducted. KM-Y did not identify all participants who crossed the risk threshold as the non-sagittal moment identified unique individuals. This result was consistent across tasks and threshold sensitivities. Analysing the peak uni-planar knee abduction moment alone is therefore likely overly reductionist, as this study demonstrates that a KM-YZ threshold identifies “at risk” individuals that a KM-Y threshold does not. Multi-planar moment metrics such as KM-YZ may help facilitate the development of screening protocols across multiple task
Simulation-Based Design of Bicuspidization of the Aortic Valve
Objective: Severe congenital aortic valve pathology in the growing patient
remains a challenging clinical scenario. Bicuspidization of the diseased aortic
valve has proven to be a promising repair technique with acceptable durability.
However, most understanding of the procedure is empirical and retrospective.
This work seeks to design the optimal gross morphology associated with surgical
bicuspidization with simulations, based on the hypothesis that modifications to
the free edge length cause or relieve stenosis.
Methods: Model bicuspid valves were constructed with varying free edge
lengths and gross morphology. Fluid-structure interaction simulations were
conducted in a single patient-specific model geometry. The models were
evaluated for primary targets of stenosis and regurgitation. Secondary targets
were assessed and included qualitative hemodynamics, geometric height,
effective height, orifice area and prolapse.
Results: Stenosis decreased with increasing free edge length and was
pronounced with free edge length less than or equal to 1.3 times the annular
diameter d. With free edge length 1.5d or greater, no stenosis occurred. All
models were free of regurgitation. Substantial prolapse occurred with free edge
length greater than or equal to 1.7d.
Conclusions: Free edge length greater than or equal to 1.5d was required to
avoid aortic stenosis in simulations. Cases with free edge length greater than
or equal to 1.7d showed excessive prolapse and other changes in gross
morphology. Cases with free edge length 1.5-1.6d have a total free edge length
approximately equal to the annular circumference and appeared optimal. These
effects should be studied in vitro and in animal studies
Drawing Arrangement Graphs In Small Grids, Or How To Play Planarity
We describe a linear-time algorithm that finds a planar drawing of every
graph of a simple line or pseudoline arrangement within a grid of area
O(n^{7/6}). No known input causes our algorithm to use area
\Omega(n^{1+\epsilon}) for any \epsilon>0; finding such an input would
represent significant progress on the famous k-set problem from discrete
geometry. Drawing line arrangement graphs is the main task in the Planarity
puzzle.Comment: 12 pages, 8 figures. To appear at 21st Int. Symp. Graph Drawing,
Bordeaux, 201
Soccer players’ perceptions on injury risk and prevention strategies
In injury prevention practice, high emphasis has been directed to the implementation and maintenance of evidence-based injury prevention measures into training routines. Despite scientific backing, compliance to injury prevention exercise programs has been observed to be suboptimal in many teams. Thus, understanding the soccer players’ beliefs, knowledge, attitude, and behaviors toward injury prevention exercise programs may unlock some insight toward better player education and compliance of injury prevention approaches implemented in their teams. In this study, we aim to gather preliminary data on Malaysian elite soccer players’ perceptions on injury risk and mechanisms, its means of prevention, and their current practice in prevention of injuries during training and matches. Active players from four elite soccer and amateur leagues (Super League, Premier League, President’s Cup, and Youth Cup) in Malaysia were invited to participate. Forty-five (n = 45) male elite players returned their responses. The most perceived risk factors for injury are muscle impairments and fatigue (91.1%), followed by coordination (88.9%), physical condition (84.4%), and previous injury (77.8%). As per our findings, over 50% of respondents feel adequately informed about injury prevention. However, as a practice, players seem to employ a combination of injury prevention measures that may or may not be supported by comprehensive, evidence-based literature. The findings suggest that there may be conflicting information among the players with regard to the efficacy of one injury prevention practice in comparison to the other. This may be regarded as a call for injury risk and prevention education among players, as well as increase the promotion of evidence-based injury prevention programs in Malaysian professional soccer
Bounded Model Checking for Probabilistic Programs
In this paper we investigate the applicability of standard model checking
approaches to verifying properties in probabilistic programming. As the
operational model for a standard probabilistic program is a potentially
infinite parametric Markov decision process, no direct adaption of existing
techniques is possible. Therefore, we propose an on-the-fly approach where the
operational model is successively created and verified via a step-wise
execution of the program. This approach enables to take key features of many
probabilistic programs into account: nondeterminism and conditioning. We
discuss the restrictions and demonstrate the scalability on several benchmarks
On the computation of zone and double zone diagrams
Classical objects in computational geometry are defined by explicit
relations. Several years ago the pioneering works of T. Asano, J. Matousek and
T. Tokuyama introduced "implicit computational geometry", in which the
geometric objects are defined by implicit relations involving sets. An
important member in this family is called "a zone diagram". The implicit nature
of zone diagrams implies, as already observed in the original works, that their
computation is a challenging task. In a continuous setting this task has been
addressed (briefly) only by these authors in the Euclidean plane with point
sites. We discuss the possibility to compute zone diagrams in a wide class of
spaces and also shed new light on their computation in the original setting.
The class of spaces, which is introduced here, includes, in particular,
Euclidean spheres and finite dimensional strictly convex normed spaces. Sites
of a general form are allowed and it is shown that a generalization of the
iterative method suggested by Asano, Matousek and Tokuyama converges to a
double zone diagram, another implicit geometric object whose existence is known
in general. Occasionally a zone diagram can be obtained from this procedure.
The actual (approximate) computation of the iterations is based on a simple
algorithm which enables the approximate computation of Voronoi diagrams in a
general setting. Our analysis also yields a few byproducts of independent
interest, such as certain topological properties of Voronoi cells (e.g., that
in the considered setting their boundaries cannot be "fat").Comment: Very slight improvements (mainly correction of a few typos); add DOI;
Ref [51] points to a freely available computer application which implements
the algorithms; to appear in Discrete & Computational Geometry (available
online
Enforcing Programming Guidelines with Region Types and Effects
We present in this paper a new type and effect system for Java which can be
used to ensure adherence to guidelines for secure web programming. The system
is based on the region and effect system by Beringer, Grabowski, and Hofmann.
It improves upon it by being parametrized over an arbitrary guideline supplied
in the form of a finite monoid or automaton and a type annotation or mockup
code for external methods. Furthermore, we add a powerful type inference based
on precise interprocedural analysis and provide an implementation in the Soot
framework which has been tested on a number of benchmarks including large parts
of the Stanford SecuriBench.Comment: long version of APLAS'17 pape
Prognostic value of myocardial perfusion scintigraphy in type 2 diabetic patients with mild, stable angina pectoris
Aim: To determine the prognostic value of reversible myocardial perfusion defects on myocardial perfusion scintigraphy (MPS) in patients with type 2 diabetes mellitus and mild anginal complaints. Methods and results: In the MERIDIAN trial, patients with diabetes mellitus type 2, stable, mild anginal symptoms (Canadian Cardiovascular Society classification (CCS) I-II/IV) and reversible perfusion defects were randomized to either continued pharmacological treatment or early invasive treatment. In this sub analysis, the severity of the myocardial perfusion defect was related to the occurrence of cardiac death and non-fatal myocardial infarction, in 319 patients (63% male, 65 ± 9 years). During follow-up (2.2 ± 0.6 years), 14 patients had a cardiac event: 3 in 171 patients without myocardial ischemia and 11 in 148 patients with myocardial ischemia. Annual event rates rose from 0.8% to 5.8% with increasing severity of myocardial ischemia. Multivariable analysis identified the presence of severe myocardial ischemia (hazard ratio (HR) 5.45, 95%CI 1.89-15.71) and insulin use (HR 4.00, 95%CI 1.25-12.75) as independent predictors of cardiac events. Conclusions: Type 2 diabetics with mild anginal symptoms with no or moderate myocardial ischemia have a low annual cardiac event rate. In patients with severe myocardial ischemia event rate increased 3-6 fold
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