236 research outputs found
The Function and Organization of the Motor System Controlling Flight Maneuvers in Flies
Animals face the daunting task of controlling their limbs using a small set of highly constrained actuators. This problem is particularly demanding for insects such as Drosophila, which must adjust wing motion for both quick voluntary maneuvers and slow compensatory reflexes using only a dozen pairs of muscles. To identify strategies by which animals execute precise actions using sparse motor networks, we imaged the activity of a complete ensemble of wing control muscles in intact, flying flies. Our experiments uncovered a remarkably efficient logic in which each of the four skeletal elements at the base of the wing are equipped with both large phasically active muscles capable of executing large changes and smaller tonically active muscles specialized for continuous fine-scaled adjustments. Based on the responses to a broad panel of visual motion stimuli, we have developed a model by which the motor array regulates aerodynamically functional features of wing motion
Nutritive Levels in Plants from Stripmined Areas in Eastern Ohio
Author Institution: Ohio Cooperative Wildlife Research Unit, The Ohio State UniversityData on nutritive quality of vegetation for stripmined lands were obtained in 1972-73 from 2 Ohio counties, one having generally acidic spoil banks and the other having calcareous spoils. Proximate analysis of water, ash, crude protein, ether extract, cell-wall constituents, and nitrogen-free extract revealed few significant differences between plants growing on stripped and undisturbed (control) plots. Plants also were analyzed for 6 essential elements by emission spectrography. Levels of potassium were significantly higher in plants from control plots. Calcium levels were higher in plants from alkaline spoils, and manganese levels were higher in plants from acidic mined plots. Manganese levels exceeded 600 ppm in some plant samples from acidic spoil banks. Even when plants from stripped plots contained significantly less of a given element, levels were generally not low enough to indicate nutrient deficiency
TEACHER COLLABORATIVE INQUIRY IN ONTARIO ELEMENTARY SCHOOLS: AN ANALYSIS OF PROVINCIAL AND SCHOOL BOARD POLICIES AND SUPPORT DOCUMENTS
Collaborative inquiry (CI) has emerged as a dominant structure for educators’ professional learning in the 21st century. The purpose of this paper is to analyze publicly available documents and policies related to CI in Ontario in order to better understand the documentary scope and spread of this professional learning model in the province. We begin by defining the parameters of CI as a dominant professional learning model before detailing our methodology for selecting and analyzing CI policies and documents at both ministry and school board levels. In our subsequent analysis, we enumerate emergent themes and findings and offer three sample case studies that illustrate how school boards in the province are documenting their experiences with CI. Finally, we conclude with a discussion of potential tensions within current CI policies as a basis for future research and policy development.
The Function and Organization of the Motor System Controlling Flight Maneuvers in Flies
Animals face the daunting task of controlling their limbs using a small set of highly constrained actuators. This problem is particularly demanding for insects such as Drosophila, which must adjust wing motion for both quick voluntary maneuvers and slow compensatory reflexes using only a dozen pairs of muscles. To identify strategies by which animals execute precise actions using sparse motor networks, we imaged the activity of a complete ensemble of wing control muscles in intact, flying flies. Our experiments uncovered a remarkably efficient logic in which each of the four skeletal elements at the base of the wing are equipped with both large phasically active muscles capable of executing large changes and smaller tonically active muscles specialized for continuous fine-scaled adjustments. Based on the responses to a broad panel of visual motion stimuli, we have developed a model by which the motor array regulates aerodynamically functional features of wing motion
Multifunctional Wing Motor Control of Song and Flight
Multifunctional motor systems produce distinct output patterns that are dependent on behavioral context, posing a challenge to underlying neuronal control. Flies use their wings for flight and the production of a patterned acoustic signal, the male courtship song, employing in both cases a small set of wing muscles and corresponding motor neurons. We took first steps toward elucidating the neuronal control mechanisms of this multifunctional motor system by live imaging of muscle ensemble activity patterns during song and flight, and we established the functional role of a comprehensive set of wing muscle motor neurons by silencing experiments. Song and flight rely on distinct configurations of neuromuscular activity, with most, but not all, flight muscles and their corresponding motor neurons contributing to song and shaping its acoustic parameters. The two behaviors are exclusive, and the neuronal command for flight overrides the command for song. The neuromodulator octopamine is a candidate for selectively stabilizing flight, but not song motor patterns
Splink: Free software for probabilistic record linkage at scale.
Funded by ADR UK, a new data linking team at the Ministry of Justice set out to link administrative datasets across the justice space, for internal use and sharing with external researchers. To achieve this aim we sought a linkage implementation that was probabilistic, flexible, scalable and ideally open source.
Taking into account the tools available at the MoJ, existing open-source software (and paid alternatives) failed to meet our desired criteria. It was decided to develop a software package that builds on FastLink’s implementation in R of an Expectation-Maximisation algorithm to estimate a Fellegi-Sunter linkage model, adding a range of technical improvements, increased functionality and customisation options. Distributed computing offered by Spark could facilitate comparable linkage jobs that run on much larger datasets and much faster. Working with government data, accountability and transparency are vital, so the data and models are made accessible by a range of intuitive visualizations.
The Splink python package has been downloaded 2 million times. This initially used Spark to deliver its superior performance, but Splink v3 caters for various SQL backends and more potential users. Splink and supplementary python libraries are publicly visible on GitHub and provide assistance in all aspects of data linkage:
- splink_data_standardisation - functions to perform general data standardisation
- splink_cluster_studio - creates an interactive HTML dashboard to analyse record clusters (building on splink_graph - a library for generating graph metrics)
- splink_synthetic_data - generating realistic synthetic data for testing linkage algorithms
- splink_demos - interactive demo/tutorial notebooks for a range of features of the Splink libraries
These tools are in continuous development and have already been used to deliver deduplicated and linked data products for the entire criminal justice system.
Through technical innovation and user-focused development, Splink has improved access to cutting-edge data linkage, and created groundbreaking research opportunities at MoJ and beyond. The team is grateful to ONS and other collaborators for testing and adopting these tools, and will continue to explore ways to improve performance and user experience
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A Microfluidic Device for Whole-Animal Drug Screening Using Electrophysiological Measures in the Nematode C. Elegans
This paper describes the fabrication and use of a microfluidic device for performing whole-animal chemical screens using non-invasive electrophysiological readouts of neuromuscular function in the nematode worm, C. elegans. The device consists of an array of microchannels to which electrodes are attached to form recording modules capable of detecting the electrical activity of the pharynx, a heart-like neuromuscular organ involved in feeding. The array is coupled to a tree-like arrangement of distribution channels that automatically delivers one nematode to each recording module. The same channels are then used to perfuse the recording modules with test solutions while recording the electropharyngeogram (EPG) from each worm with sufficient sensitivity to detect each pharyngeal contraction. The device accurately reported the acute effects of known anthelmintics (anti-nematode drugs) and also correctly distinguished a specific drug-resistant mutant strain of C. elegans from wild type. The approach described here is readily adaptable to parasitic species for the identification of novel anthelmintics. It is also applicable in toxicology and drug discovery programs for human metabolic and degenerative diseases for which C. elegans is used as a model.Chemistry and Chemical Biolog
A stochastic neuronal model predicts random search behaviors at multiple spatial scales in C. elegans
Random search is a behavioral strategy used by organisms from bacteria to humans to locate food that is randomly distributed and undetectable at a distance. We investigated this behavior in the nematode Caenorhabditis elegans, an organism with a small, well-described nervous system. Here we formulate a mathematical model of random search abstracted from the C. elegans connectome and fit to a large-scale kinematic analysis of C. elegans behavior at submicron resolution. The model predicts behavioral effects of neuronal ablations and genetic perturbations, as well as unexpected aspects of wild type behavior. The predictive success of the model indicates that random search in C. elegans can be understood in terms of a neuronal flip-flop circuit involving reciprocal inhibition between two populations of stochastic neurons. Our findings establish a unified theoretical framework for understanding C. elegans locomotion and a testable neuronal model of random search that can be applied to other organisms
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Highly Efficient Generation of Heritable Zebrafish Gene Mutations Using Homo- and Heterodimeric TALENs
Transcription activator-like effector nucleases (TALENs) are powerful new research tools that enable targeted gene disruption in a wide variety of model organisms. Recent work has shown that TALENs can induce mutations in endogenous zebrafish genes, but to date only four genes have been altered, and larger-scale tests of the success rate, mutation efficiencies and germline transmission rates have not been described. Here, we constructed homodimeric TALENs to 10 different targets in various endogenous zebrafish genes and found that 7 nuclease pairs induced targeted indel mutations with high efficiencies ranging from 2 to 76%. We also tested obligate heterodimeric TALENs and found that these nucleases induce mutations with comparable or higher frequencies and have better toxicity profiles than their homodimeric counterparts. Importantly, mutations induced by both homodimeric and heterodimeric TALENs are passed efficiently through the germline, in some cases reaching 100% transmission. For one target gene sequence, we observed substantially reduced mutagenesis efficiency for a variant site bearing two mismatched nucleotides, raising the possibility that TALENs might be used to perform allele-specific gene disruption. Our results suggest that construction of one to two heterodimeric TALEN pairs for any given gene will, in most cases, enable researchers to rapidly generate knockout zebrafish
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Assessing the impact of climate change on sweet potato in Uganda
Sweet potato is a mainstay of household food security and a major source of vitamin A across sub-Saharan Africa, and particularly in Uganda. Understanding how climate change is likely to impact on sweet potato would be useful for policymakers in Uganda making decisions to improve food security and increase resilience to climate shocks. However, sweet potato is an under-researched crop and the impacts of climate change have not been systematically analysed. The Sweet Potato Catalyst Project aims to assess the impacts of climate change on sweet potato in Uganda and develop ways for local stakeholders to access and assess this information to strengthen governance. This policy briefing note provides an overview of the research, the approach being taken and anticipated outcomes that will feed into the UNFCCC Koronovia Joint Work on Agriculture
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