LEARNING AND VERIFYING SAFETY CONSTRAINTS FOR PLANNERS IN A KNOWLEDGE‐IMPOVERISHED SYSTEM

We present a Bayesian approach to learning flexible safety constraints and subsequently verifying whether plans satisfy these constraints. Our approach, called the Safety Constraint Learner/Checker (SCLC), infers safety constraints from a single expert demonstration trace and minimal background knowledge, and applies these constraints to the solutions proposed by multiple planning agents in an integrated and heterogeneous ensemble. The SCLC calculates how much to blame plan fragments (partial solutions) generated by the individual planning agents. This information is used when composing these fragments into a final overall plan. In particular, fragments whose safety violations exceed a threshold are rejected. This facilitates the generation of safe plans. We have integrated the SCLC within the Generalized Integrated Learning Architecture, which was designed for Defense Advanced Research Projects Agency (DARPA)’s Integrated Learning (IL) program. The main goal of the IL program is to promote the development and success of sophisticated systems that learn to solve challenging real‐world problems based on a simple demonstration by a human expert and exiguous domain knowledge. We present experimental results showing the advantages of the SCLC on two multiagent problem‐solving tasks that were benchmark applications in DARPA’s IL program.     

The explanatory power of citations: a new approach to unpacking impact in science

Scientometrics - Citation analysis has been applied to map the landscape of scientific disciplines and to assess the impact of publications. However, it is limited in that it assumes all citations...     

A short questionnaire for problem drinkers. An empirical analysis (author's transl)

This short questionnaire for alcoholics (KFA) has so far been used as an aid for the clinical diagnosis of alcoholism. In the presented empirical study the KFA was tested on its efficiency as an independent diagnostic instrument for the identification of alcoholics. The questionnaire was given to 120 male alcoholics and 80 male controls (nonalcoholic inpatients). Its validity (correlation of test scores by independent criterion) of r = 0.81 with a reliability of r = 0.94 is fairly high, considering the nature of our control group being inpatients in contrast to the normally used healthy controls. A further improvement of discrimination could be achieved in weighting certain items. On this basis given a cutting score of 6 points the misclassifications in both alcoholics and controls could be reduced to 4%. Allowing this error rate the KFA can be considered a suitable test for the identification of alcoholics.     

Zone-dependent mechanical properties of human articular cartilage obtained by indentation measurements

Emerging 3D printing technology permits innovative approaches to manufacture cartilage scaffolds associated with layer-by-layer mechanical property adaptation. However, information about gradients of mechanical properties in human articular cartilage is limited. In this study, we quantified a zone-dependent change of local elastic modulus of human femoral condyle cartilage by using an instrumented indentation technique. From the cartilage superficial zone towards the calcified layer, a gradient of elastic modulus values between 0.020?±?0.003?MPa and 6.44?±?1.02?MPa was measured. To validate the tissue quality, the histological tissue composition was visualized by glycosaminoglycan and collagen staining. This work aims to introduce a new protocol to investigate the zone-dependent mechanical properties of graded structures, such as human articular cartilage. From this knowledge, better cartilage repair strategies could be tailored in the future.