GPI PSF subtraction with TLOCI: the next evolution in exoplanet/disk high-contrast imaging

To directly image exoplanets and faint circumstellar disks, the noisy stellar halo must be suppressed to a high level. To achieve this feat, the angular differential imaging observing technique and the least-squares Locally Optimized Combination of Images (LOCI) algorithm have now become the standard in single band direct imaging observations and data reduction. With the development and commissioning of new high-order high-contrast adaptive optics equipped with integral field units, the image subtraction algorithm needs to be modified to allow the optimal use of polychromatic images, field-rotated images and archival data. A new algorithm, TLOCI (for Template LOCI), is designed to achieve this task by maximizing a companion signal-to-noise ratio instead of simply minimizing the noise as in the original LOCI algorithm. The TLOCI technique uses an input spectrum and template Point Spread Functions (PSFs, generated from unocculted and unsaturated stellar images) to optimize the reference image least-squares coefficients to minimize the planet self-subtraction, thus maximizing its throughput per wavelength, while simultaneously providing a maximum suppression of the speckle noise. The new algorithm has been developed using on-sky GPI data and has achieved impressive contrast. This paper presents the TLOCI algorithm, on-sky performance, and will discuss the challenges in recovering the planet spectrum with high fidelity.Comment: 13 pages, 8 figures, to appear in Proceedings of SPIE 914

Integrative Genomics Reveals the Genetics and Evolution of the Honey Bee’s Social Immune System

Social organisms combat pathogens through individual innate immune responses or through social immunity—behaviors among individuals that limit pathogen transmission within groups. Although we have a relatively detailed understanding of the genetics and evolution of the innate immune system of animals, we know little about social immunity. Addressing this knowledge gap is crucial for understanding how life-history traits influence immunity, and identifying if trade-offs exist between innate and social immunity. Hygienic behavior in the Western honey bee, Apis mellifera, provides an excellent model for investigating the genetics and evolution of social immunity in animals. This heritable, colony-level behavior is performed by nurse bees when they detect and remove infected or dead brood from the colony. We sequenced 125 haploid genomes from two artificially selected highly hygienic populations and a baseline unselected population. Genomic contrasts allowed us to identify a minimum of 73 genes tentatively associated with hygienic behavior. Many genes were within previously discovered QTLs associated with hygienic behavior and were predictive of hygienic behavior within the unselected population. These genes were often involved in neuronal development and sensory perception in solitary insects. We found that genes associated with hygienic behavior have evidence of positive selection within honey bees (Apis), supporting the hypothesis that social immunity contributes to fitness. Our results indicate that genes influencing developmental neurobiology and behavior in solitary insects may have been co-opted to give rise to a novel and adaptive social immune phenotype in honey bees.York University Librarie

Translating community resilience theory into practice: A deliberative Delphi approach

Despite the availability of important theoretical insights that could enhance the resilience of rural communities to complex challenges, there is a paucity of guidance on how to apply these insights in practice. This article therefore presents and assesses a deliberative research process using the Delphi technique to elicit expert knowledge from 22 academics, community practitioners and policymakers working in roles related to community resilience delivery in rural Scotland. The participants co-produced an operational framework for community resilience, with support from researchers who facilitated the three-stage, interactive process. The methodology enabled participants to work together in an iterative and inclusive manner, culminating in the collective development of a conceptual framework consisting of eight resilience-enabling factors and corresponding criteria for monitoring change, which can be used to plan practical action and provide feedback to enable ongoing adaptation. The process also produced an in-depth understanding of participants’ perceptions of rural community resilience, identified key factors that enable or impede rural community resilience, analysed the potential to assess community resilience and explored scale-related issues. The article explores the implications of this framework for those working to make rural communities more resilient and reflects on the benefits and wider application of this type of research approach for developing shared understandings of complex concepts.</p

Seshat: The Global History Databank

The vast amount of knowledge about past human societies has not been systematically organized and, therefore, remains inaccessible for empirically testing theories about cultural evolution and historical dynamics. For example, what evolutionary mechanisms were involved in the transition from the small-scale, uncentralized societies, in which humans lived 10,000 years ago, to the large-scale societies with an extensive division of labor, great differentials in wealth and power, and elaborate governance structures of today? Why do modern states sometimes fail to meet the basic needs of their populations? Why do economies decline, or fail to grow? In this article, we describe the structure and uses of a massive databank of historical and archaeological information, Seshat: The Global History Databank. The data that we are currently entering in Seshat will allow us and others to test theories explaining how modern societies evolved from ancestral ones, and why modern societies vary so much in their capacity to satisfy their members’ basic human needs

A Macroscope for Global History. Seshat Global History Databank: a methodological overview

This article introduces the ‘Seshat: Global History’ project, the methodology it is based upon and its potential as a tool for historians and other humanists. The article describes in detail how the Seshat methodology and platform can be used to tackle big questions that play out over long time scales whilst allowing users to drill down to the detail and place every single data point both in its historic and historiographical context. Seshat thus offers a platform underpinned by a rigorous methodology to actually do 'longue durée' history and the article argues for the need for humanists and social scientists to engage with data driven ‘longue durée' history. The article argues that Seshat offers a much needed infrastructure in which different skills sets and disciplines can come together to analyze the past using long timescales. In addition to highlighting the theoretical and methodological underpinnings, the potential of Seshat is demonstrated by showcasing three case studies. Each of these case studies is centred around a set of long standing questions and historiographical debates and it is argued that the introduction of a Seshat approach has the potential to radically alter our understanding of these questions

Understanding the response to Covid-19 - Exploring options for a resilient social and economic recovery in Scotland’s rural and island communities

What were we trying to find out?This research considered the impacts of Covid-19 on rural and island communities, how resiliently they have responded; and the most effective ways forward for their recovery.What did we do?Our research approach involved: interviewing people in key rural sectors then producing a map to identify factors of resilience. This map was used to identify case study communities. Interviews were undertaken in these communities to understand local perspectives.What did we learn?Rural and island communities have been vulnerable to the impacts of Covid. Specific factors that have increased their vulnerability include reliance on limited employment sectors, being located far from centralised services (e.g. hospitals), limited digital connectivity; and an ageing population. Communities with a more resilient response had some or all of the following features: a strong sense of community; community organisations and local businesses that have been responsive to local needs; the existence of strategic partnerships between community organisations and the public/private sector; and good digital connectivity.What needs to change in the future?Covid-19 has brought rural vulnerabilities into sharp focus and these vulnerabilities are often connected. Strategic and joined-up partnerships between community, public and private sector organisations will remain important, as well as novel and flexible funding mechanisms to enable place-based and context-specific responses.What do we recommend?This research highlighted nine actions that would assist rural and island communities to thrive in the future. These include:1. Building on existing and new partnerships and supporting anchor organisations2. Capitalising on and rewarding community spirit3. Encouraging and supporting young people to move to rural and island communities4. Retaining and enhancing digital connectivity opportunities5. Supporting adaptable local businesses6. Strategic partnerships with deliver place-based solutions7. Continue to support diversification of the rural economy8. Enhancing the knowledge base on local-regional vulnerabilities9. Retaining a flexible, targeted and responsive approach to financial support

Calibration of the instrumental polarization effects of SCExAO-CHARIS’ spectropolarimetric mode

SCExAO at the Subaru telescope is a visible and near-infrared high-contrast imaging instrument employing extreme adaptive optics and coronagraphy. The instrument feeds the near-infrared light (JHK) to the integral field spectrograph CHARIS. Recently, a Wollaston prism was added to CHARIS’ optical path, giving CHARIS a spectropolarimetric capability that is unique among high-contrast imaging instruments. We present a comprehensive and detailed Mueller matrix model describing the instrumental polarization effects of the complete optical path, thus the telescope and instrument, using measurements with the internal source and observations of standard stars. The 22 wavelength bins of CHARIS provide a unique opportunity to investigate in detail the wavelength dependence of the instrumental polarization effects. We find that the image derotator (K-mirror) produces strongly wavelength-dependent crosstalk, in the worst case converting ~95% of the incident linear polarization to circularly polarized light that cannot be measured. We fit the crosstalk of the half-wave plate (HWP) for all wavelengths with a simple two-parameter model of an achromatic HWP consisting of a layer of quartz and a layer of MgF2. While the magnitude of the telescope-induced polarization varies with wavelength, its angle varies solely with the altitude angle of the telescope. We show initial steps toward correcting on-sky data for the instrumental polarization effects, with which we aim to achieve a polarimetric accuracy <0.1% in the degree of linear polarization. Our calibrations of CHARIS’ spectropolarimetric mode enable unique quantitative polarimetric studies of circumstellar disks and planetary and brown dwarf companions

Calibration of the instrumental polarization effects of SCExAO-CHARIS’ spectropolarimetric mode

SCExAO at the Subaru telescope is a visible and near-infrared high-contrast imaging instrument employing extreme adaptive optics and coronagraphy. The instrument feeds the near-infrared light (JHK) to the integral field spectrograph CHARIS. Recently, a Wollaston prism was added to CHARIS’ optical path, giving CHARIS a spectropolarimetric capability that is unique among high-contrast imaging instruments. We present a comprehensive and detailed Mueller matrix model describing the instrumental polarization effects of the complete optical path, thus the telescope and instrument, using measurements with the internal source and observations of standard stars. The 22 wavelength bins of CHARIS provide a unique opportunity to investigate in detail the wavelength dependence of the instrumental polarization effects. We find that the image derotator (K-mirror) produces strongly wavelength-dependent crosstalk, in the worst case converting ~95% of the incident linear polarization to circularly polarized light that cannot be measured. We fit the crosstalk of the half-wave plate (HWP) for all wavelengths with a simple two-parameter model of an achromatic HWP consisting of a layer of quartz and a layer of MgF2. While the magnitude of the telescope-induced polarization varies with wavelength, its angle varies solely with the altitude angle of the telescope. We show initial steps toward correcting on-sky data for the instrumental polarization effects, with which we aim to achieve a polarimetric accuracy <0.1% in the degree of linear polarization. Our calibrations of CHARIS’ spectropolarimetric mode enable unique quantitative polarimetric studies of circumstellar disks and planetary and brown dwarf companions