Segmentation of the Izu-Bonin and Mariana slabs based on the analysis of the Benioff seismicity distribution and regional tomography results

We present a new model of P and S velocity anomalies in the mantle down to a depth of 1300 km beneath the Izu-Bonin and Mariana (IBM) arcs. This model is derived based on tomographic inversion of global travel time data from the revised ISC catalogue. The results of inversion are thoroughly verified using a series of different tests. The obtained model is generally consistent with previous studies by different authors. We also present the distribution of relocated deep events projected to the vertical surface along the IBM arc system. Unexpectedly, the seismicity forms elongated vertical clusters instead of horizontal zones indicating phase transitions in the slab. We propose that these vertical seismicity zones mark zones of intense deformation and boundaries between semi-autonomous segments of the subducting plate. The P and S seismic tomography models consistently display the slab as prominent high-velocity anomalies coinciding with the distribution of deep seismicity. We can distinguish at least four segments which subduct differently. The northernmost segment of the Izu-Bonin arc has the gentlest angle of dipping which is explained by backward displacement of the trench. In the second segment, the trench stayed at the same location, and we observe the accumulation of the slab material in the transition zone and its further descending to the lower mantle. In the third segment, the trench is moving forward causing the steepening of the slab. Finally, for the Mariana segment, despite the backward displacement of the arc, the subducting slab is nearly vertical. Between the Izu-Bonin and Mariana arcs we clearly observe a gap which can be traced down to about 400 km in depth. Based on joint consideration of the tomography results and the seismicity distribution, we propose two different scenarios of the subduction evolution in the IBM zone during the recent time, depending on the reference frame of plate displacements. In the first case, we consider the movements in respect to the Philippine Plate, and explain the different styles of the subduction by the relative backward and forward migrations of the trench. In the second case, all the elements of the subduction system move westward in respect to the stable Asia. Different subduction styles are explained by the "anchoring" of selected segments of the slab, different physical properties of the subducting plate and the existence of buoyant rigid blocks related to sea mount and igneous provinces

Measuring Pain Withdrawal Threshold using a Novel Device in Pseudo-continuous Mode

The study of pain and analgesia is an important area of biomedical research that has led to a significant number of advances in the treatment of acute and chronic pain. This study introduces a novel approach to mechanical testing of pain withdrawal of a rat hind paw to a stimulus. This systematic method involves a modified electronic esthesiometer controlled by an IDEA drive that allows for consistency in experiments. The device gives the experimenter computer control of the step size and velocity of approach of the probe stimulus. We discuss here some of the limitations in the current techniques used and illustrate how this device will result in reduced errors during an experiment. The standard method primarily involves manually raising the probe towards the animal. The data presented herein shows how the computer controlled pseudo-continuous mode of operation is effective in determining the pain threshold with a lesser deviation from the mean

Influence of the Processes of Fluffing the Flax Stem Strips on the Structural Parameters of the Layer

Introduction. The efficiency of separating long flax fiber from the flax straw largely depends on the structural parameters of the layer of flax stems. Modern fluffers for flax strips create random distortions and intersection of the layer of flax stems under the pick-up drum. These disadvantages of existing machines are minimized in an experimental fluffer, in which a layer of flax stems moves over the pick-up drum with a kinematic mode indicator equal to one. Aim of the Article. The study is aimed at finding means and methods for preserving the structural parameters of the layer of flax stems when fluffing flax straw strips. Materials and Methods. Experimental studies were carried out according to existing and newly developed methods, and the analysis of flax fiber was carried out according to the current GOST standards. The experiments were carried out on the flax strips formed by the LC-4A flax harvester. After grass sprouted through the strips of flax stems, they were fluffed with the serial machine VL-3 and an experimental fluffer. For each variant, the necessary measurements of the main structural parameters of the stem strip and collection of samples for analysis were made before the unit passed and after fluffering the flax stem strip. The results of measurements and processing of samples were processed using the methods of mathematical statistics. Results. It was found that macro-bends of the original and processed flax strips were in all the experiments. At the same time, the range of changes in the curvature of the flax strip outside the cutoff frequencies expanded 2.3 times under the influence of the working tools of the serial tedder VL-3. The randomness of these pulsations was caused by an increase in the distortion and elongation of the flax stems in the strip by 6.0° and 6.9%, respectively. At the same time, the experimental fluffer produced the smallest changes in the structural parameters of the flax stem layer. The technological evaluation of the flax straw confirmed the advantages of the experimental fluffer in comparison with the serial VL-3, which has an average production of long fiber higher by 0.65% and 0.5 units of number. Discussion and Conclusion. The analysis of the obtained results indicates the practicability of fluffing flax strips by picking up and moving the stems from above the pick-up drum with its kinematic mode index equal to one

Relevance of mytilid shell microtopographies for fouling defence - a global comparison

Prevention of epibiosis is of vital importance for most aquatic organisms, which can have consequences for their ability to invade new areas. Surface microtopography of the shell periostracum has been shown to have antifouling properties for mytilid mussels, and the topography shows regional differences. This article examines whether an optimal shell design exists and evaluates the degree to which shell microstructure is matched with the properties of the local fouling community. Biomimics of four mytilid species from different regional provenances were exposed at eight different sites in both northern and southern hemispheres. Tendencies of the microtopography to both inhibit and facilitate fouling were detected after 3 and 6 weeks of immersion. However, on a global scale, all microtopographies failed to prevent fouling in a consistent manner when exposed to various fouling communities and when decoupled from other shell properties. It is therefore suggested that the recently discovered chemical anti-microfouling properties of the periostracum complement the anti-macrofouling defence offered by shell microtopography

A mean-field kinetic lattice gas model of electrochemical cells

We develop Electrochemical Mean-Field Kinetic Equations (EMFKE) to simulate electrochemical cells. We start from a microscopic lattice-gas model with charged particles, and build mean-field kinetic equations following the lines of earlier work for neutral particles. We include the Poisson equation to account for the influence of the electric field on ion migration, and oxido-reduction processes on the electrode surfaces to allow for growth and dissolution. We confirm the viability of our approach by simulating (i) the electrochemical equilibrium at flat electrodes, which displays the correct charged double-layer, (ii) the growth kinetics of one-dimensional electrochemical cells during growth and dissolution, and (iii) electrochemical dendrites in two dimensions.Comment: 14 pages twocolumn, 17 figure

Plasma Characterization of Hall Thruster with Active and Passive Segmented Electrodes

Non-emissive electrodes and ceramic spacers placed along the Hall thruster channel are shown to affect the plasma potential distribution and the thruster operation. These effects are associated with physical properties of the electrode material and depend on the electrode configuration, geometry and the magnetic field distribution. An emissive segmented electrode was able to maintain thruster operation by supplying an additional electron flux to sustain the plasma discharge between the anode and cathode neutralizer. These results indicate the possibility of new configurations for segmented electrode Hall thruster

Recruitment in the sea: bacterial genes required for inducing larval settlement in a polychaete worm

Metamorphically competent larvae of the marine tubeworm Hydroides elegans can be induced to metamorphose by biofilms of the bacterium Pseudoalteromonas luteoviolacea strain HI1. Mutational analysis was used to identify four genes that are necessary for metamorphic induction and encode functions that may be related to cell adhesion and bacterial secretion systems. No major differences in biofilm characteristics, such as biofilm cell density, thickness, biomass and EPS biomass, were seen between biofilms composed of P. luteoviolacea (HI1) and mutants lacking one of the four genes. The analysis indicates that factors other than those relating to physical characteristics of biofilms are critical to the inductive capacity of P. luteoviolacea (HI1), and that essential inductive molecular components are missing in the non-inductive deletion-mutant strains

Development of Bacterial Biofilms on Artificial Corals in Comparison to Surface-Associated Microbes of Hard Corals

Numerous studies have demonstrated the differences in bacterial communities associated with corals versus those in their surrounding environment. However, these environmental samples often represent vastly different microbial micro-environments with few studies having looked at the settlement and growth of bacteria on surfaces similar to corals. As a result, it is difficult to determine which bacteria are associated specifically with coral tissue surfaces. In this study, early stages of passive settlement from the water column to artificial coral surfaces (formation of a biofilm) were assessed. Changes in bacterial diversity (16S rRNA gene), were studied on artificially created resin nubbins that were modelled from the skeleton of the reef building coral Acropora muricata. These models were dip-coated in sterile agar, mounted in situ on the reef and followed over time to monitor bacterial community succession. The bacterial community forming the biofilms remained significantly different (R = 0.864 p<0.05) from that of the water column and from the surface mucus layer (SML) of the coral at all times from 30 min to 96 h. The water column was dominated by members of the α-proteobacteria, the developed community on the biofilms dominated by γ-proteobacteria, whereas that within the SML was composed of a more diverse array of groups. Bacterial communities present within the SML do not appear to arise from passive settlement from the water column, but instead appear to have become established through a selection process. This selection process was shown to be dependent on some aspects of the physico-chemical structure of the settlement surface, since agar-coated slides showed distinct communities to coral-shaped surfaces. However, no significant differences were found between different surface coatings, including plain agar and agar enhanced with coral mucus exudates. Therefore future work should consider physico-chemical surface properties as factors governing change in microbial diversity

Коллизионная система Западного Прибайкалья: аэрокосмическая геологическая карта Ольхонского региона (Байкал, Россия)

We announce the second edition of the Aerospace geological map of the Olkhon Region (Baikal, Russia), scale 1:40 000, which was published in 2017. The map has been considerably revised and updated, and its changes are critical for correct understanding of the regional geology, tectonics and geodynamics. Only a small number of its printed copies have been released, and therefore the map may not be available for all interested specialists. The electronic version of the map is available for studying and/or printing (see the link to its pdf file in the paper’s supplement). The pdf file is about 68 MB, i.e. small compared to the original map (more than 5 GB), but the quality is maintained. The map does not show the base layer due to the terms of the licenses owned by the companies and satellite owners.Настоящее краткое сообщение является в значительной степени анонсом второго издания Аэрокосмической геологической карты Ольхонского региона (Байкал, Россия) м-ба 1:40000, изданной в 2017 г. Изменения по сравнению с первым изданием карты весьма значительны и принципиально важны для понимания геологии, тектоники и геодинамики региона. Карта отпечатана небольшим тиражом, поэтому вряд ли будет доступна всем заинтересованным специалистам. В статье же приводится ссылка на электронный вариант карты (pdf-файл), размещенный в дополнительных материалах к статье на сайте журнала, который можно изучать или распечатывать для пользования. Размер электронного варианта файла карты (около 68 Мб) невелик по сравнению с оригиналом (более 5 Гб), однако потери качества нет, из него только удален базовый слой по условиям лицензий, полученных от компаний и владельцев спутников