494 research outputs found
Ordered Navigation on Multi-attributed Data Words
We study temporal logics and automata on multi-attributed data words.
Recently, BD-LTL was introduced as a temporal logic on data words extending LTL
by navigation along positions of single data values. As allowing for navigation
wrt. tuples of data values renders the logic undecidable, we introduce ND-LTL,
an extension of BD-LTL by a restricted form of tuple-navigation. While complete
ND-LTL is still undecidable, the two natural fragments allowing for either
future or past navigation along data values are shown to be Ackermann-hard, yet
decidability is obtained by reduction to nested multi-counter systems. To this
end, we introduce and study nested variants of data automata as an intermediate
model simplifying the constructions. To complement these results we show that
imposing the same restrictions on BD-LTL yields two 2ExpSpace-complete
fragments while satisfiability for the full logic is known to be as hard as
reachability in Petri nets
Second International Competition on Runtime Verification: CRV 2015
International audienceWe report on the Second International Competition on Run-time Verification (CRV-2015). The competition was held as a satellite event of the 15th International Conference on Runtime Verification (RV'15). The competition consisted of three tracks: o✏ine monitoring, online monitoring of C programs, and online monitoring of Java programs. This report describes the format of the competition, the participating teams and submitted benchmarks. We give an example illustrating the two main inputs expected from the participating teams, namely a benchmark (i.e., a program and a property on this program) and a monitor for this benchmark. We also propose some reflection based on the lessons learned
Composite Interstage Structural Concept Down Select Process and Results
NASA's Advanced Composites Technologies (ACT) project evaluated several composite construction options for the Ares V Interstage to support the Constellation Program's goal of reducing the mass of vehicle dry structures. In Phase 1 of the project, eight candidate construction concepts were evaluated for the Ares V Interstage design. Trade studies were performed using finite element analyses to determine weight estimates for the construction concepts. An evaluation process was then used to down select the construction concepts down to two concepts for further consideration in Phase 2 of the project. In Phase 2 of the project, additional trade studies were performed using detailed finite element analyses of the Interstage and a final down select process was used to choose the recommended Interstage construction concept. The results of the study showed that a honeycomb sandwich design was the most favorable Interstage construction concept based on advantages in manufacturing cost. Details of the Phase 1 and Phase 2 trade studies and down select process with final results are presented in the paper
Model-Checking Counting Temporal Logics on Flat Structures
We study several extensions of linear-time and computation-tree temporal logics with quantifiers that allow for counting how often certain properties hold. For most of these extensions, the model-checking problem is undecidable, but we show that decidability can be recovered by considering flat Kripke structures where each state belongs to at most one simple loop. Most decision procedures are based on results on (flat) counter systems where counters are used to implement the evaluation of counting operators
Short communication: Cemented implant reconstructions are associated with less marginal bone loss than screw-retained reconstructions at 3 and 5 years of loading
OBJECTIVES
To analyse whether there is a difference in marginal bone levels (MBL) and the respective changes between cemented and screw-retained reconstructions at 3 and 5 years of loading.
METHODS
Radiographic data from 14 prospective multicentre clinical trials following implant loading with fixed cemented (CEM) or screw-retained (SCREW) reconstructions with a 3- to 5-year follow-up were retrieved from a database. MBL and MBL changes were assessed at initiation of implant loading (BL), at 3 (FU-3) and 5 years (FU-5) thereafter. The presence of peri-implantitis was also determined.
RESULTS
Data from 1,672 implants at BL, 1,565 implants at FU-3 and 1,109 implants at FU-5 were available. The mean MBL amounted to 0.57 mm (SD 0.87) at BL, 0.55 mm (SD 0.86) at FU-3 and 0.65 mm (SD 1.18) at FU-5. At FU-3, the mean MBL was 0.44 mm (SD 0.65) in group CEM and 0.63 mm (SD 0.99) in group SCREW showing a significant difference between the groups (intergroup <0.05). At FU-5, the mean MBL was 0.42 mm (SD 0.77) in CEM and 0.80 mm (SD 1.37) in SCREW, again with significant differences between both groups (p < .05). MBL changes between BL and FU-3 amounted to 0.11 mm (SD 1.02) (bone loss) in SCREW and -0.17 mm (SD 1.03) (bone gain) in CEM. Similarly, mean MBL changes from BL to FU-5 amounted to 0.23 mm (SD 1.31) (bone loss) in SCREW and -0.26 mm (SD 1.27) (bone gain) in CEM. The prevalence of peri-implantitis amounted to 6.9% in CEM and 5.6% in group SCREW (intergroup p = .29063) at FU-3. At FU-5, peri-implantitis amounted to 4.6% in CEM and 6.2% in group SCREW (intergroup p = .28242).
CONCLUSION
Cemented implant reconstructions compared with screw-retained reconstructions revealed higher marginal bone levels and similar rates of peri-implantitis during 5 years. The difference in MBL and the respective changes between the two groups, however, appear to be clinically negligible
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