Control at stability's edge minimizes energetic costs: expert stick balancing.

Stick balancing on the fingertip is a complex voluntary motor task that requires the stabilization of an unstable system. For seated expert stick balancers, the time delay is 0.23 s, the shortest stick that can be balanced for 240 s is 0.32 m and there is a [Formula: see text]° dead zone for the estimation of the vertical displacement angle in the saggital plane. These observations motivate a switching-type, pendulum-cart model for balance control which uses an internal model to compensate for the time delay by predicting the sensory consequences of the stick's movements. Numerical simulations using the semi-discretization method suggest that the feedback gains are tuned near the edge of stability. For these choices of the feedback gains, the cost function which takes into account the position of the fingertip and the corrective forces is minimized. Thus, expert stick balancers optimize control with a combination of quick manoeuvrability and minimum energy expenditures.

Longitudinal HCR-20 scores in a high-secure psychiatric hospital.

BACKGROUND: The HCR-20 is a widely used 20 item structured professional judgement aid to risk assessment and management, but longitudinal studies of its value are rare, particularly with people at high risk of reoffending. AIMS: To investigate whether the HCR-20 discriminates between patient subgroups in one high-security hospital in England, whether scores reduce with hospital treatment and whether lower scores predict discharge. METHODS: Repeated HCR-20 ratings were made by clinical teams across five services within the hospital, two of them (women and men with intellectual disability) national services. A database of 3337 HCR-20 ratings, from 532 patients over a period of 5 years, was examined using mixed effects models. RESULTS: As expected, HCR-20 scores were high overall, but there were differences between services in the ratings obtained. Female patients and men with intellectual disability had the highest total score. There was a significant relationship between discharge and lower clinical risk score, but not between total and risk scale scores and discharge. There were significant changes in scores over time, although these were small and may not be clinically meaningful. Differences between services were observed, with women evidencing greater change. CONCLUSIONS: It is unsurprising that patients in two national services (for men with intellectual disability and women) have the highest HCR-20 scores; however, the finding of relatively greater risk reduction in women needs further investigation. Although we did not find ceiling effects in this sample, the clinical value of frequently repeated HCR-20 ratings may be limited for high-risk populations where any change is likely to be slow.

Accurate whole human genome sequencing using reversible terminator chemistry.

DNA sequence information underpins genetic research, enabling discoveries of important biological or medical benefit. Sequencing projects have traditionally used long (400-800 base pair) reads, but the existence of reference sequences for the human and many other genomes makes it possible to develop new, fast approaches to re-sequencing, whereby shorter reads are compared to a reference to identify intraspecies genetic variation. Here we report an approach that generates several billion bases of accurate nucleotide sequence per experiment at low cost. Single molecules of DNA are attached to a flat surface, amplified in situ and used as templates for synthetic sequencing with fluorescent reversible terminator deoxyribonucleotides. Images of the surface are analysed to generate high-quality sequence. We demonstrate application of this approach to human genome sequencing on flow-sorted X chromosomes and then scale the approach to determine the genome sequence of a male Yoruba from Ibadan, Nigeria. We build an accurate consensus sequence from >30x average depth of paired 35-base reads. We characterize four million single-nucleotide polymorphisms and four hundred thousand structural variants, many of which were previously unknown. Our approach is effective for accurate, rapid and economical whole-genome re-sequencing and many other biomedical applications.