A Theory of Cheap Control in Embodied Systems

We present a framework for designing cheap control architectures for embodied agents. Our derivation is guided by the classical problem of universal approximation, whereby we explore the possibility of exploiting the agent's embodiment for a new and more efficient universal approximation of behaviors generated by sensorimotor control. This embodied universal approximation is compared with the classical non-embodied universal approximation. To exemplify our approach, we present a detailed quantitative case study for policy models defined in terms of conditional restricted Boltzmann machines. In contrast to non-embodied universal approximation, which requires an exponential number of parameters, in the embodied setting we are able to generate all possible behaviors with a drastically smaller model, thus obtaining cheap universal approximation. We test and corroborate the theory experimentally with a six-legged walking machine. The experiments show that the sufficient controller complexity predicted by our theory is tight, which means that the theory has direct practical implications. Keywords: cheap design, embodiment, sensorimotor loop, universal approximation, conditional restricted Boltzmann machineComment: 27 pages, 10 figure

An SU(N) Mott insulator of an atomic Fermi gas realized by large-spin Pomeranchuk cooling

The Hubbard model, containing only the minimum ingredients of nearest neighbor hopping and on-site interaction for correlated electrons, has succeeded in accounting for diverse phenomena observed in solid-state materials. One of the interesting extensions is to enlarge its spin symmetry to SU(N>2), which is closely related to systems with orbital degeneracy. Here we report a successful formation of the SU(6) symmetric Mott insulator state with an atomic Fermi gas of ytterbium (173Yb) in a three-dimensional optical lattice. Besides the suppression of compressibility and the existence of charge excitation gap which characterize a Mott insulating phase, we reveal an important difference between the cases of SU(6) and SU(2) in the achievable temperature as the consequence of different entropy carried by an isolated spin. This is analogous to Pomeranchuk cooling in solid 3He and will be helpful for investigating exotic quantum phases of SU(N) Hubbard system at extremely low temperatures.Comment: 20 pages, 6 figures, to appear in Nature Physic

TRY plant trait database - enhanced coverage and open access

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

A call for the appropriate application of clinical pharmacological principles in the search for safe and efficacious COVID-19 (SARS-COV-2) treatments.

Syndrome Coronavirus 2 (SARS-CoV-2) has led to remarkable efforts by the scientific communities internationally to identify potential pharmacological treatments through the rapid initiation of clinical trials of novel and/or re-purposed regulatory authorityapproved therapies. We greatly welcome the significant global effort to safely expedite trials. However, we are concerned that many studies have not been of high quality to generate clinically meaningful data to enable effective translation to clinical practice. Identifying the “right” drug (or drug combinations) is only the first step. Applying core clinical pharmacology principles at all stages of research will help identify the right dose, the right patient, and the right treatment protocol. We hope that by setting out the principles outlined in this statement, efforts to find a safe and efficacious treatment for COVID-19 will have the best chance of success

Conservation genetics of the annual hemiparasitic plant Melampyrum sylvaticum (Orobanchaceae) in the UK and Scandinavia

Melampyrum sylvaticum is an endangered annual hemiparasitic plant that is found in only 19 small and isolated populations in the United Kingdom (UK). To evaluate the genetic consequences of this patchy distribution we compared levels of diversity, inbreeding and differentiation from ten populations from the UK with eight relatively large populations from Sweden and Norway where the species is more continuously distributed. We demonstrate that in both the UK and Scandinavia, the species is highly inbreeding (global F IS = 0.899). Levels of population differentiation were high (F’ST = 0.892) and significantly higher amongst UK populations (F’ST = 0.949) than Scandinavian populations (F’ST = 0.762; P < 0.01). The isolated populations in the UK have, on average, lower genetic diversity (allelic richness, proportion of loci that are polymorphic, gene diversity) than Scandinavian populations, and this diversity difference is associated with the smaller census size and population area of UK populations. From a conservation perspective, the naturally inbreeding nature of the species may buffer the species against immediate effects of inbreeding depression, but the markedly lower levels of genetic diversity in UK populations may represent a genetic constraint to evolutionary change. In addition, the high levels of population differentiation suggest that gene flow among populations will not be effective at replenishing lost variation. We thus recommend supporting in situ conservation management with ex situ populations and human-mediated seed dispersal among selected populations in the UK

Threatened reef corals of the world

10.1371/journal.pone.0034459PLoS ONE73

Community participation for rural healthcare design: description and critique of a method

This paper outlines a community participation process that was developed to engage rural community stakeholders in designing new health services. The paper explains what led up to the process and provides critique around applying the process for other health services and in other communities. Internationally, community participation is widely invoked, but it is only broadly explained in the literature, other than reviews of outcomes or descriptions of problems. This paper provides an actual process, derived from iterative research, that others could use, but explains caveats in the method and its application. From developing this method of community participation for service design, we conclude that rather than being a benign and inherently ‘good thing’, community participation is a process into which health services managers and communities should enter cautiously. Stronger parameters around desirable outcomes and awareness of potential pitfalls in the process are important to address

Assessing Natural Resource Use by Forest-Reliant Communities in Madagascar Using Functional Diversity and Functional Redundancy Metrics

Biodiversity plays an integral role in the livelihoods of subsistence-based forest-dwelling communities and as a consequence it is increasingly important to develop quantitative approaches that capture not only changes in taxonomic diversity, but also variation in natural resources and provisioning services. We apply a functional diversity metric originally developed for addressing questions in community ecology to assess utilitarian diversity of 56 forest plots in Madagascar. The use categories for utilitarian plants were determined using expert knowledge and household questionnaires. We used a null model approach to examine the utilitarian (functional) diversity and utilitarian redundancy present within ecological communities. Additionally, variables that might influence fluctuations in utilitarian diversity and redundancy—specifically number of felled trees, number of trails, basal area, canopy height, elevation, distance from village—were analyzed using Generalized Linear Models (GLMs). Eighteen of the 56 plots showed utilitarian diversity values significantly higher than expected. This result indicates that these habitats exhibited a low degree of utilitarian redundancy and were therefore comprised of plants with relatively distinct utilitarian properties. One implication of this finding is that minor losses in species richness may result in reductions in utilitarian diversity and redundancy, which may limit local residents' ability to switch between alternative choices. The GLM analysis showed that the most predictive model included basal area, canopy height and distance from village, which suggests that variation in utilitarian redundancy may be a result of local residents harvesting resources from the protected area. Our approach permits an assessment of the diversity of provisioning services available to local communities, offering unique insights that would not be possible using traditional taxonomic diversity measures. These analyses introduce another tool available to conservation biologists for assessing how future losses in biodiversity will lead to a reduction in natural resources and provisioning services from forests

A Common Origin for Neutrino Anarchy and Charged Hierarchies

The generation of exponential flavor hierarchies from extra-dimensional wavefunction overlaps is re-examined. We find, surprisingly, that coexistence of anarchic fermion mass matrices with such hierarchies is intrinsic and natural to this setting. The salient features of charged fermion and neutrino masses and mixings can thereby be captured within a single framework. Both Dirac and Majorana neutrinos can be realized. The minimal phenomenological consequences are discussed, including the need for a fundamental scale far above the weak scale to adequately suppress flavor-changing neutral currents. Two broad scenarios for stabilizing this electroweak hierarchy are studied, warped compactification and supersymmetry. In warped compactifications and "Flavorful Supersymmetry," where non-trivial flavor structure appears in the new TeV physics, Dirac neutrinos are strongly favored over Majorana by lepton flavor violation tests. We argue that this is part of a more general result for flavor-sensitive TeV-scale physics. Our scenario strongly suggests that the supersymmetric flavor problem is not solved locally in the extra dimension, but rather at or below the compactification scale. In the supersymmetric Dirac case, we discuss how the appearance of light right-handed sneutrinos considerably alters the physics of dark matter.Comment: Comparison with the Froggatt-Nielsen mechanism omitted. Some clarifications added. This is the version accepted by PRL with a longer abstract

Efeitos da estimulação da sucção não nutritiva com dedo enluvado na transição alimentar em recém-nascido prematuro de muito baixo peso

Objetivos analisar os efeitos da estimulação da sucção não nutritiva com a técnica do dedo enluvado, sobre o início e a transição alimentar da via gástrica para a via oral em prematuros de muito baixo peso. Métodos estudo aleatório, prospectivo, longitudinal, experimental e controlado, que incluiu 40 prematuros internados na UTI Neonatal do Hospital de Clínicas, com idade gestacional £ 32 semanas e peso de nascimento £ 1500g, clinicamente estáveis. Os prematuros foram distribuídos aleatoriamente, por meio de sorteio, em 2 grupos: grupo controle, sem SNN e grupo experimental, com SNN com dedo enluvado, 3 vezes ao dia, 3 dias na semana. Foram avaliados critérios quanto ao escore da avaliação da prontidão para início da alimentação oral, intercorrências durante a sucção nutritiva (SN) e o tempo de transição alimentar. Resultados quando comparado o grupo experimental em relação ao grupo controle observou-se um escore significantemente maior na avaliação da prontidão para início da alimentação via oral, uma menor frequência de sinais de estresse durante a sucção nutritiva e um menor tempo de transição alimentar da via gástrica para via oral. Conclusão a estimulação da sucção não nutritiva com a técnica do dedo enluvado melhorou a prontidão do prematuro para início da alimentação via oral, diminuiu a frequência dos sinais de estresse durante a alimentação via oral e reduziu o tempo de transição alimentar no grupo experimental quando comparado ao grupo controle