Predictive prey pursuit in a whiskered robot

Highly active small mammals need to capture prey rapidly and with a high success rate if they are to survive. We consider the case of the Etruscan shrew, which hunts prey including crickets almost as large as itself, and relies on its whiskers (vibrissae) to complete a kill. We model this hunting behaviour using a whiskered robot. Shrews strike rapidly and accurately after gathering very limited sensory information; we attempt to match this performance by using model-based simultaneous discrimination and localisation of a ‘prey’ robot (i.e. by using strong priors). We report performance that is comparable, given the spatial and temporal scale differences, to shrew performance in most respects

Storage capacity of a constructive learning algorithm

Upper and lower bounds for the typical storage capacity of a constructive algorithm, the Tilinglike Learning Algorithm for the Parity Machine [M. Biehl and M. Opper, Phys. Rev. A {\bf 44} 6888 (1991)], are determined in the asymptotic limit of large training set sizes. The properties of a perceptron with threshold, learning a training set of patterns having a biased distribution of targets, needed as an intermediate step in the capacity calculation, are determined analytically. The lower bound for the capacity, determined with a cavity method, is proportional to the number of hidden units. The upper bound, obtained with the hypothesis of replica symmetry, is close to the one predicted by Mitchinson and Durbin [Biol. Cyber. {\bf 60} 345 (1989)].Comment: 13 pages, 1 figur

A biomimetic vocalisation system for MiRo

There is increasing interest in the use of animal-like robots in applications such as companionship and pet therapy. However, in the majority of cases it is only the robot's physical appearance that mimics a given animal. In contrast, MiRo is the first commercial biomimetic robot to be based on a hardware and software architecture that is modelled on the biological brain. This paper describes how MiRo's vocalisation system was designed, not using pre-recorded animal sounds, but based on the implementation of a real-time parametric general-purpose mammalian vocal synthesiser tailored to the specific physical characteristics of the robot. The novel outcome has been the creation of an 'appropriate' voice for MiRo that is perfectly aligned to the physical and behavioural affordances of the robot, thereby avoiding the 'uncanny valley' effect and contributing strongly to the effectiveness of MiRo as an interactive device

Do Black, Asian and Minority Ethnic nurses and midwives experience a career delay? A cross-sectional survey investigating career progression barriers

Background Black, Asian and Minority Ethnic nurses and midwives are under-represented in higher and managerial roles. Aims This study explored the presence and nature of career progression delays for Black, Asian and Minority Ethnic nurses and midwives and investigated where the barriers to progression were. Design A secondary analysis of data from a wider cross-sectional survey investigating workplace experiences, burnout and patient safety in nurses and midwives. Methods 538 nurses and midwives were recruited from four UK hospitals between February and March 2017. A career progression delay was viewed as being present if Black, Asian and Minority Ethnic nurses and midwives had spent longer on the entry level nursing grade and less time on higher grades in the previous 10 years. The analysis included items pertaining to: receipt of professional training, perceived managerial support for progression, likelihood of submitting applications and application success rates. Data were analysed using linear regression, odds ratios and t-tests. Results were reported using the STROBE Checklist. Results Black, Asian and Minority Ethnic nurses and midwives (n = 104; 19.4%) had spent more months working at the entry-level grade (M = 75.75, SD = 44.90) than White nurses and midwives (n = 428; 79.7%; M = 41.85, SD = 44.02, p < 0.001) and fewer months at higher grades (M = 15.29, SD = 30.94 v 29.33, SD = 39.78, p = 0.006 at Band 6; M = 6.54, SD = 22.59 v M = 19.68, SD = 37.83, p = 0.001 at Band 7) over the previous 10 years. Black, Asian and Minority Ethnic nurses and midwives were less likely to have received professional training in the previous year (N = 53; 53.0% v N = 274; 66.0%, p = 0.015) and had to apply for significantly more posts than White nurses and midwives before gaining their first post on their current band (M = 1.22, SD = 1.51 v M = 0.81, SD = 1.55, p = 0.026). Conclusions Interventions are needed to improve racial equality regarding career progression in nurses and midwives. Increasing access to professional training and reducing discriminatory practice in job recruitment procedures may be beneficial

Microscopy techniques for determining water-cement (w/c) ratio in hardened concrete: A round-robin assessment

Water to cement (w/c) ratio is usually the most important parameter specified in concrete design and is sometimes the subject of dispute when a shortfall in concrete strength or durability is an issue. However, determination of w/c ratio in hardened concrete by testing is very difficult once the concrete has set. This paper presents the results from an inter-laboratory round-robin study organised by the Applied Petrography Group to evaluate and compare microscopy methods for measuring w/c ratio in hardened concrete. Five concrete prisms with w/c ratios ranging from 0.35 to 0.55, but otherwise identical in mix design were prepared independently and distributed to 11 participating petrographic laboratories across Europe. Participants used a range of methods routine to their laboratory and these are broadly divided into visual assessment, measurement of fluorescent intensity and quantitative backscattered electron microscopy. Some participants determined w/c ratio using more than one method or operator. Consequently, 100 individual w/c ratio determinations were collected, representing the largest study of its type ever undertaken. The majority (81%) of the results are accurate to within ± 0.1 of the target mix w/c ratios, 58% come to within ± 0.05 and 37% are within ± 0.025. The study shows that microscopy-based methods are more accurate and reliable compared to the BS 1881-124 physicochemical method for determining w/c ratio. The practical significance, potential sources of errors and limitations are discussed with the view to inform future applications

Improving the Thermal Stability of Cellobiohydrolase Cel7A from \u3cem\u3eHypocrea jecorina\u3c/em\u3e by Directed Evolution

Secreted mixtures of Hypocrea jecorina cellulases are able to efficiently degrade cellulosic biomass to fermentable sugars at large, commercially relevant scales. H. jecorina Cel7A, cellobiohydrolase I, from glycoside hydrolase family 7, is the workhorse enzyme of the process. However, the thermal stability of Cel7A limits its use to processes where temperatures are no higher than 50 °C. Enhanced thermal stability is desirable to enable the use of higher processing temperatures and to improve the economic feasibility of industrial biomass conversion. Here, we enhanced the thermal stability of Cel7A through directed evolution. Sites with increased thermal stability properties were combined, and a Cel7A variant (FCA398) was obtained, which exhibited a 10.4 °C increase in Tm and a 44-fold greater half-life compared with the wild-type enzyme. This Cel7A variant contains 18 mutated sites and is active under application conditions up to at least 75 °C. The X-ray crystal structure of the catalytic domain was determined at 2.1 Å resolution and showed that the effects of the mutations are local and do not introduce major backbone conformational changes. Molecular dynamics simulations revealed that the catalytic domain of wild-type Cel7A and the FCA398 variant exhibit similar behavior at 300 K, whereas at elevated temperature (475 and 525 K), the FCA398 variant fluctuates less and maintains more native contacts over time. Combining the structural and dynamic investigations, rationales were developed for the stabilizing effect at many of the mutated sites

The co-evolution of the genome and epigenome in colorectal cancer.

Colorectal malignancies are a leading cause of cancer-related death1 and have undergone extensive genomic study2,3. However, DNA mutations alone do not fully explain malignant transformation4-7. Here we investigate the co-evolution of the genome and epigenome of colorectal tumours at single-clone resolution using spatial multi-omic profiling of individual glands. We collected 1,370 samples from 30 primary cancers and 8 concomitant adenomas and generated 1,207 chromatin accessibility profiles, 527 whole genomes and 297 whole transcriptomes. We found positive selection for DNA mutations in chromatin modifier genes and recurrent somatic chromatin accessibility alterations, including in regulatory regions of cancer driver genes that were otherwise devoid of genetic mutations. Genome-wide alterations in accessibility for transcription factor binding involved CTCF, downregulation of interferon and increased accessibility for SOX and HOX transcription factor families, suggesting the involvement of developmental genes during tumourigenesis. Somatic chromatin accessibility alterations were heritable and distinguished adenomas from cancers. Mutational signature analysis showed that the epigenome in turn influences the accumulation of DNA mutations. This study provides a map of genetic and epigenetic tumour heterogeneity, with fundamental implications for understanding colorectal cancer biology

Phenotypic plasticity and genetic control in colorectal cancer evolution.

Genetic and epigenetic variation, together with transcriptional plasticity, contribute to intratumour heterogeneity1. The interplay of these biological processes and their respective contributions to tumour evolution remain unknown. Here we show that intratumour genetic ancestry only infrequently affects gene expression traits and subclonal evolution in colorectal cancer (CRC). Using spatially resolved paired whole-genome and transcriptome sequencing, we find that the majority of intratumour variation in gene expression is not strongly heritable but rather 'plastic'. Somatic expression quantitative trait loci analysis identified a number of putative genetic controls of expression by cis-acting coding and non-coding mutations, the majority of which were clonal within a tumour, alongside frequent structural alterations. Consistently, computational inference on the spatial patterning of tumour phylogenies finds that a considerable proportion of CRCs did not show evidence of subclonal selection, with only a subset of putative genetic drivers associated with subclone expansions. Spatial intermixing of clones is common, with some tumours growing exponentially and others only at the periphery. Together, our data suggest that most genetic intratumour variation in CRC has no major phenotypic consequence and that transcriptional plasticity is, instead, widespread within a tumour