Hydrodynamic analysis of suspension feeding in recent and fossil crinoids

Recent stalked crinoids live primarily in the deep sea. First representatives are known from the Ordovician, and were very abundant during several time intervals of the Palaeozoic and Mesozoic era. Living crinoids are passive suspension feeders and typically arrange their body in the so-called parabolic filtration fan, where the arms are bent backwards into the incoming flow. The fossil record provides representatives that differ significantly in their morphology from that of the living forms and were very abundant in shallow water habitats. For those crinoids, different feeding positions have to be assumed. In the presented study, physical models of the recent Hyocrinus sp. and the fossil Encrinus liliiformis were studied in a recirculating flow tank using Particle Image Velocimetry (PIV) to investigate the flow patterns forming around the crowns. In addition, 3D models of the crinoids were analysed with computer simulations applying Computational Fluid Dynamics (CFD). PIV and CFD results were validated against each other, and CFD was then used to investigate additional models including the more complex recent crinoid Neocrinus decorus, a submodel of part of an arm with several pinnules and tube feet, as well as different flow conditions and feeding positions of E. liliiformis. Results for the recent crinoids adopting the parabolic filtration fan showed straight flow of the water through the arms and pinnules. The crown induces a baffling effect such that nutritive particles are slowed down and can be caught by the extended tube feet. The submodel including the finer morphological structures leads to the development of local, small scale recirculation behind the tube feet, but almost no particles are transported back to the oral surface in this current. For the fossil crinoid E. liliiformis, which was probably not able to bend its arms to such an extant as living crinoids, both PIV and CFD results supported a different filtering position, where the crown forms a tearshape. With an aboral inflow and velocities of more than 0.01 m/s, this feeding position results in a recirculation of water into the crown. Particle tracking simulations showed that nutritive particles are then transported onto the oral surface. An opening of the arms increases the strength of the recirculation current, whereas the absence of parts of three arms decreases the recirculation considerably. Inflow from the lateral as well as oral side enables direct catchment of plankton out of the water. The postulated feeding position of E. liliiformis thus worked effectively under varying flow conditions that typically occurred in the shallow water habitats of the Middle Triassic Muschelkalk, which this crinoid inhabited.Gestielte Crinoiden leben heute, bis auf wenige Ausnahmen, nur noch in der Tiefsee. Sie weisen einen weit zurückreichenden Fossilbericht auf, mit den ersten sicheren Vertretern im Ordovizium. Während des Paläozoikums und Mesozoikums waren sie zeitweise sehr weit verbreitet und besiedelten ausgedehnte Areale in Flachwasserbereichen. Rezente Crinoiden gehören zu den passiven Filtrierern und biegen ihre Arme entgegen der Strömungsrichtung in eine charakteristische Filtrierposition, den parabolischen Filtrationsfächer. Zahlreiche fossile Formen unterscheiden sich morphologisch jedoch stark von den heutigen, so dass für diese Crinoiden andere Filtrierpositionen angenommen werden können. In der vorliegenden Studie wurde die Umströmung handgefertigter Modelle der rezenten Crinoide Hyocrinus sp. und der fossilen Crinoide Encrinus liliiformis in einem Strömungskanal mittels Particle Image Velocimetry (PIV) gemessen. Parallel hierzu erfolgte die Analyse von 3D Modellen mithilfe von Computersimulationen unter Anwendung von Computational Fluid Dynamics (CFD). Die Resultate beider Methoden wurden miteinander verglichen, und CFD im Folgenden angewendet, um erweiterte Modelle zu untersuchen. Diese umfassen die komplexer aufgebaute rezente Crinoide Neocrinus decorus, ein Submodell eines Arms mit meheren Pinnulae und Ambulakralfüßchen, sowie verschiedene Strömungsbedingungen und Filtrierpositionen von E. liliiformis. Die Resultate der Strömungsanalyse der rezenten Crinoiden, die den parabolischen Filtrationsfächer bilden, zeigten eine gerade Durchströmung der Arme und Pinnulae. Die Krone führt zu einer Verlangsamung des Wassers und der darin enthaltenen Nahrungspartikel, die so von den ausgestreckten Ambulakralfüßchen eingefangen werden können. Die Analyse des Submodelles ließ erkennen, dass sich hinter den Ambulakralfüßchen engbegrenzte Rezirkulationszonen ausbilden, die allerdings kaum Partikel transportieren. Für die fossile Seelilie E. liliiformis, die ihre Arme wahrscheinlich nicht wie die heutigen Crinoiden biegen konnte, unterstützten die Untersuchungen eine andere Filtrierposition, bei der die Krone eine Tropfenform bildet. Bei einer aboralen Anströmung mit Geschwindigkeiten über 0.01 m/s führt diese Position zur Entstehung einer Rezirkulation des Wassers in die Krone. Die „Particle Tracking“-Simulationen ergaben, dass Nahrungspartikel so zur Filteroberfläche zurücktransportiert werden. Ein Öffnen der Arme verstärkt die rezirkulierende Strömung, das Fehlen dreier Armteile schwächt die Rezirkulation deutlich ab. Bei einer Anströmung aus lateraler oder oraler Richtung können die Partikel direkt aus der Strömung eingefangen werden. Die vorgestellte Filtrierposition von E. liliiformis erweist sich daher als funktionstüchtig unter sich ändernden Strömungsbedingungen, wie sie typischerweise in den Flachwasserhabitaten im Muschelkalk der Mitteltrias auftraten

Low-Cost PM2.5 Sensors Can Help Identify Driving Factors of Poor Air Quality and Benefit Communities

Air quality is critical for public health. Residents rely chiefly on government agencies such as the Environmental Protection Agency (EPA) in the United States to establish standards for the measurement of harmful contaminants including ozone, sulfur dioxide, carbon monoxide, volatile organic chemicals (VOCs), and fine particulate matter at or below 2.5 μm. According to the California Air Resources Board [1], “short-term PM2.5 exposure (up to 24-h duration) has been associated with premature mortality, increased hospital admissions for heart or lung causes, acute and chronic bronchitis, asthma attacks, emergency room visits, respiratory symptoms, and restricted activity days”. While public agency resources may provide guidance, it is often inadequate relative to the widespread need for effective local measurement and management of air quality risks. To that end, this paper explores the use of low-cost PM2.5 sensors for measuring air quality through micro-scale (local) analytical comparisons with reference grade monitors and identification of potential causal factors of elevated sensor readings. We find that a) there is high correlation between the PM2.5 measurements of low-cost sensors and reference grade monitors, assessed through calibration models, b) low-cost sensors are more prevalent and provide more frequent measurements, and c) low-cost sensor data enables exploratory and explanatory analytics to identify potential causes of elevated PM2.5 readings. This understanding should encourage community scientists to place more low-cost sensors in their neighborhoods, which can empower communities to demand policy changes that are necessary to reduce particle pollution, and provide a basis for subsequent research

Determining the range of influence of tourist trails users on naturally valuable areas : a proposal of a method and a practical example

Purpose: The aim of the article is to present the proprietary methodology for determining the area range of anthropopressure to areas of natural value located along tourist trails and to the entire area where those trails are located. Design/Methodology/Approach: A method of critical analysis of information obtained from various dispersed sources was used to determine the widths of the buffers of the impact of tourists using various types of tourist trails on the environment. Current geodetic and cartographic studies as well as geoportals and thematic websites available on the Internet were used to properly define the course of tourist routes. Spatial analyzes were performed using the ArcGIS software environment. Findings: The results of the research confirm that the proposed simple, cheap and effective methodology allows to take into account many elements of nature and to consider the range of pressure on valuable natural areas as a whole or only on their selected element. It also allows to choose the form of tourist activities in the analyzed area. Practical Implications: The proposed method can be helpful in the management of protected areas, including, for example, the assessment of the tourist capacity of the area and the development of opinions on the creation of new and updating or correction of the existing tourist trails. Originality/Value: Authors presented an algorithm of the most important activities and types of spatial analyzes necessary to identify the extent of the impact of people using various types of tourist trails on naturally valuable areaspeer-reviewe

The aromatic/arginine selectivity filter of NIP aquaporins plays a critical role in substrate selectivity for silicon, boron, and arsenic

Nodulin-26-like intrinsic proteins (NIPs) of the aquaporin family are involved in the transport of diverse solutes, but the mechanisms controlling the selectivity of transport substrates are poorly understood. The purpose of this study was to investigate how the aromatic/arginine (ar/R) selectivity filter influences the substrate selectivity of two NIP aquaporins; the silicic acid (Si) transporter OsLsi1 (OsNIP2;1) from rice and the boric acid (B) transporter AtNIP5;1 from Arabidopsis; both proteins are also permeable to arsenite. Native and site-directed mutagenized variants of the two genes were expressed in Xenopus oocytes and the transport activities for Si, B, arsenite, and water were assayed. Substitution of the amino acid at the ar/R second helix (H2) position of OsLsi1 did not affect the transport activities for Si, B, and arsenite, but that at the H5 position resulted in a total loss of Si and B transport activities and a partial loss of arsenite transport activity. Conversely, changes of the AtNIP5;1 ar/R selectivity filter and the NPA motifs to the OsLsi1 type did not result in a gain of Si transport activity. B transport activity was partially lost in the H5 mutant but unaffected in the H2 mutant of AtNIP5;1. In contrast, both the single and double mutations at the H2 and/or H5 positions of AtNIP5;1 did not affect arsenite transport activity. The results reveal that the residue at the H5 position of the ar/R filter of both OsLsi1 and AtNIP5;1 plays a key role in the permeability to Si and B, but there is a relatively low selectivity for arsenite

Pion emission from the T2K replica target: method, results and application

The T2K long-baseline neutrino oscillation experiment in Japan needs precise predictions of the initial neutrino flux. The highest precision can be reached based on detailed measurements of hadron emission from the same target as used by T2K exposed to a proton beam of the same kinetic energy of 30 GeV. The corresponding data were recorded in 2007-2010 by the NA61/SHINE experiment at the CERN SPS using a replica of the T2K graphite target. In this paper details of the experiment, data taking, data analysis method and results from the 2007 pilot run are presented. Furthermore, the application of the NA61/SHINE measurements to the predictions of the T2K initial neutrino flux is described and discussed.Comment: updated version as published by NIM

Multiplicity and transverse momentum fluctuations in inelastic proton-proton interactions at the CERN Super Proton Synchrotron

Measurements of multiplicity and transverse momentum fluctuations of charged particles were performed in inelastic p+p interactions at 20, 31, 40, 80 and 158 GeV/c beam momentum. Results for the scaled variance of the multiplicity distribution and for three strongly intensive measures of multiplicity and transverse momentum fluctuations \$\Delta[P_{T},N]\$, \$\Sigma[P_{T},N]\$ and \$\Phi_{p_T}\$ are presented. For the first time the results on fluctuations are fully corrected for experimental biases. The results on multiplicity and transverse momentum fluctuations significantly deviate from expectations for the independent particle production. They also depend on charges of selected hadrons. The string-resonance Monte Carlo models EPOS and UrQMD do not describe the data. The scaled variance of multiplicity fluctuations is significantly higher in inelastic p+p interactions than in central Pb+Pb collisions measured by NA49 at the same energy per nucleon. This is in qualitative disagreement with the predictions of the Wounded Nucleon Model. Within the statistical framework the enhanced multiplicity fluctuations in inelastic p+p interactions can be interpreted as due to event-by-event fluctuations of the fireball energy and/or volume.Comment: 18 pages, 12 figure

NA61/SHINE facility at the CERN SPS: beams and detector system

NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) is a multi-purpose experimental facility to study hadron production in hadron-proton, hadron-nucleus and nucleus-nucleus collisions at the CERN Super Proton Synchrotron. It recorded the first physics data with hadron beams in 2009 and with ion beams (secondary 7Be beams) in 2011. NA61/SHINE has greatly profited from the long development of the CERN proton and ion sources and the accelerator chain as well as the H2 beamline of the CERN North Area. The latter has recently been modified to also serve as a fragment separator as needed to produce the Be beams for NA61/SHINE. Numerous components of the NA61/SHINE set-up were inherited from its predecessors, in particular, the last one, the NA49 experiment. Important new detectors and upgrades of the legacy equipment were introduced by the NA61/SHINE Collaboration. This paper describes the state of the NA61/SHINE facility - the beams and the detector system - before the CERN Long Shutdown I, which started in March 2013