Accelerating root system phenotyping of seedlings through a computer-assisted processing pipeline

Background: There are numerous systems and techniques to measure the growth of plant roots. However, phenotyping large numbers of plant roots for breeding and genetic analyses remains challenging. One major difficulty is to achieve high throughput and resolution at a reasonable cost per plant sample. Here we describe a cost-effective root phenotyping pipeline, on which we perform time and accuracy benchmarking to identify bottlenecks in such pipelines and strategies for their acceleration. Results: Our root phenotyping pipeline was assembled with custom software and low cost material and equipment. Results show that sample preparation and handling of samples during screening are the most time consuming task in root phenotyping. Algorithms can be used to speed up the extraction of root traits from image data, but when applied to large numbers of images, there is a trade-off between time of processing the data and errors contained in the database. Conclusions: Scaling-up root phenotyping to large numbers of genotypes will require not only automation of sample preparation and sample handling, but also efficient algorithms for error detection for more reliable replacement of manual interventions

North Atlantic summer storm tracks over Europe dominated by internal variability over the past millennium

Certain large sustained anomalies in European temperatures in the last millennium do not match estimations of external climate forcing, and are likely the result of internal climate variations. Should these anomalies occur again in the future, they could be large enough to significantly modulate the response of European temperatures from the expected response to greenhouse forcing. Here, we use temperature observations, simulations and reconstructions over the past millennium to show that, whilst continental multidecadal mean summer temperature has varied within a span of 1K and is primarily controlled by external forcing, subcontinental deviations from the mean, described by the temperature contrast between northern and south Europe (the meridional temperature gradient, MTG), vary within a span of 2K (simulation estimated) and are primarily controlled by internal climatic processes. These processes comprise internally generated redistributions of precipitation and cloud cover that are linked to vacillations in the position of the summer storm track. In contrast to the 20th century, the summer storm-track has varied stochastically over the past millennium, with a weak response to external forcing. The future response of European summer temperatures to anthropogenic greenhouse forcing is likely to be spatially modulated by stochastic internal processes which have caused cool, damp summers in northern Europe over multiple periods of the last millennium, and over the last two decades

Data Descriptor: A global multiproxy database for temperature reconstructions of the Common Era

Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850-2014. Global temperature composites show a remarkable degree of coherence between high-and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python.(TABLE)Since the pioneering work of D'Arrigo and Jacoby1-3, as well as Mann et al. 4,5, temperature reconstructions of the Common Era have become a key component of climate assessments6-9. Such reconstructions depend strongly on the composition of the underlying network of climate proxies10, and it is therefore critical for the climate community to have access to a community-vetted, quality-controlled database of temperature-sensitive records stored in a self-describing format. The Past Global Changes (PAGES) 2k consortium, a self-organized, international group of experts, recently assembled such a database, and used it to reconstruct surface temperature over continental-scale regions11 (hereafter, ` PAGES2k-2013').This data descriptor presents version 2.0.0 of the PAGES2k proxy temperature database (Data Citation 1). It augments the PAGES2k-2013 collection of terrestrial records with marine records assembled by the Ocean2k working group at centennial12 and annual13 time scales. In addition to these previously published data compilations, this version includes substantially more records, extensive new metadata, and validation. Furthermore, the selection criteria for records included in this version are applied more uniformly and transparently across regions, resulting in a more cohesive data product.This data descriptor describes the contents of the database, the criteria for inclusion, and quantifies the relation of each record with instrumental temperature. In addition, the paleotemperature time series are summarized as composites to highlight the most salient decadal-to centennial-scale behaviour of the dataset and check mutual consistency between paleoclimate archives. We provide extensive Matlab code to probe the database-processing, filtering and aggregating it in various ways to investigate temperature variability over the Common Era. The unique approach to data stewardship and code-sharing employed here is designed to enable an unprecedented scale of investigation of the temperature history of the Common Era, by the scientific community and citizen-scientists alike

Effects of severe operating conditions (high loads/low rotational speeds) on sleeve journal bearings

Journal bearings are often employed in rotating machines and several papers deal with their modelling and design. On the contrary, experimental tests are seldom presented, in particular when the bearings are used in severe operating conditions, i.e. with very high values of specific pressure and very low rotational speeds. This paper presents an experimental investigation about the influence of the applied static load on the behavior of a cylindrical journal bearing with two axial grooves. The profiles of the pressure and the oil-film thickness during the shaft rotation have been measured by one pressure probe and one proximity probe installed in the rotating shaft. Measurements of the shaft center position, dynamic coefficients, hydrodynamic pressure, temperature distributions on the bearing, oil-film thickness, and bearing profile deformation under several operating conditions are presented and discussed

Comparative transcriptome analyses of seven anurans reveal functions and adaptations of amphibian skin

Roof and dormer windows; The site where Samuel de Champlain founded the first permanent French settlement in North America in 1608. Place Royale is part of the historic area that earned Old Québec recognition from the United Nations Educational, Scientific and Cultural Organization (UNESCO) in 1985. In 1682 fire destroyed 55 houses. With reconstruction came new efforts for fire protection. New building standards gave rise to the urban architecture that is typical of Place-Royale: tall stone buildings, separated by fire-resistant walls, with no outside decoration of wood. Place-Royale, then called the "market square", was above all the centre of trade in New France. From 1633, when hundreds of Amerindians came to a major fur fair, until 1759, the square was a hub of activity. All European imports were brought ashore and all exports were loaded on ships at Québec City. Source: Musée de la civilisation museological complex [website]; http://www.mcq.org/en/mcq/index.html (accessed 7/14/2008