The emerald ash borer (EAB),
, is an invasive beetle of East Asian origin that has killed millions of ash trees (
spp.) in North America and Russia. In September 2020, EAB was detected in Saint ...Petersburg, a notable event for the metropolitan city. The aim of the present study was to investigate the occurrence and ecology of EAB in Saint Petersburg. The presence of two distinct enclave populations of EAB was revealed, each of which has, most likely, been established through separate events of "hitchhiking" via transport vehicles. Following the invasion, the further spread of EAB in Saint Petersburg was slow and locally restricted, most likely due to climatic factors. This spread by "hitchhiking" suggests that the possibility of the further long-distance geographic spread of EAB in the Baltic Sea region (the EU) is high, both by ground transport (120-130 km distance from EU borders) and ferries that transport cars across the Baltic Sea. In certain cases, the development of EAB on
based on the stem portion colonized, larval densities, number of galleries, exit holes, viable larvae, and emerged adult beetles, was more successful than in
trees. The observed relatively high sensitivity of
to EAB, therefore, casts doubt on the efficacy and benefits of the currently ongoing selection and breeding projects against ash dieback (ADB) disease, which is caused by the fungus
. Inventory, mapping, and monitoring of surviving
trees infested by both ADB and EAB are necessary to acquire genetic resources for work on the strategic long-term restoration of
, tackling the probable invasion of EAB to the EU.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The previous orthogonal ridge/transform staircase geometry south of Iceland is being progressively changed to the present continuous oblique Reykjanes Ridge spreading geometry as North ...America–Eurasia transform faults are successively eliminated from north to south. This reorganization is commonly interpreted as a thermal phenomenon, caused by warmer Iceland plume mantle progressively interacting with the ridge, although other diachronous seafloor spreading reorganizations are thought to result from tectonic rift propagation. New marine geophysical data covering our reinterpretation of the reorganization tip near 57°N show successive transform eliminations at a propagation velocity of ∼110 km/Myr, ten times the spreading half rate, followed by abrupt reorganization slowing at the Modred transform as it was converted to a migrating non-transform offset. Neither the simple thermal model nor the simple propagating rift model appears adequate to explain the complicated plate boundary reorganization process.
•Revised interpretation of the active North Atlantic reorganization tip location.•New marine geophysical data reveal the recent Reykjanes Ridge reorganization history.•Rapid successive transform eliminations before abrupt slowing at the Modred transform.•Modred transform fault converted to non-transform offset at the reorganization tip.•Simple thermal and propagating rift models are inadequate to explain the new data.
Using a combined approach of seafloor mapping, MAPR and CTD survey, we report evidence for active hydrothermal venting along the 130°‐140°E section of the poorly‐known South‐East Indian Ridge (SEIR) ...from the Australia‐Antarctic Discordance (AAD) to the George V Fracture Zone (FZ). Along the latter, we report Eh and CH4 anomalies in the water column above a serpentinite massif, which unambiguously testify for ultramafic‐related fluid flow. This is the first time that such circulation is observed on an intermediate‐spreading ridge. The ridge axis itself is characterized by numerous off‐axis volcanoes, suggesting a high magma supply. The water column survey indicates the presence of at least ten distinct hydrothermal plumes along the axis. The CH4:Mn ratios of the plumes vary from 0.37 to 0.65 denoting different underlying processes, from typical basalt‐hosted to ultramafic‐hosted high‐temperature hydrothermal circulation. Our data suggest that the change of mantle temperature along the SEIR not only regulates the magma supply, but also the hydrothermal activity. The distribution of hydrothermal plumes from a ridge segment to another implies secondary controls such as the presence of fractures and faults along the axis or in the axial discontinuities. We conclude from these results that hydrothermal activity along the SEIR is controlled by magmatic processes at the regional scale and by the tectonics at the segment scale, which influences the type of hydrothermal circulation and leads to various chemical compositions. Such variety may impact global biogeochemical cycles, especially in the Southern Ocean where hydrothermal venting might be the only source of nutrients.
Key Points
Intense and contrasted hydrothermal activity has been evidenced along the South‐East Indian Ridge in the Furious Fifties
Ultramafic circulation is evidenced in the George V FZ, which is the first observation of this type along an intermediate‐spreading ridge
Chemical compositions of the plumes reveal various regional and local controls on the hydrothermal circulation
Abstract
Using a combined approach of seafloor mapping, MAPR and CTD survey, we report evidence for active hydrothermal venting along the 130°‐140°E section of the poorly‐known South‐East Indian ...Ridge (SEIR) from the Australia‐Antarctic Discordance (AAD) to the George V Fracture Zone (FZ). Along the latter, we report Eh and CH
4
anomalies in the water column above a serpentinite massif, which unambiguously testify for ultramafic‐related fluid flow. This is the first time that such circulation is observed on an intermediate‐spreading ridge. The ridge axis itself is characterized by numerous off‐axis volcanoes, suggesting a high magma supply. The water column survey indicates the presence of at least ten distinct hydrothermal plumes along the axis. The CH
4
:Mn ratios of the plumes vary from 0.37 to 0.65 denoting different underlying processes, from typical basalt‐hosted to ultramafic‐hosted high‐temperature hydrothermal circulation. Our data suggest that the change of mantle temperature along the SEIR not only regulates the magma supply, but also the hydrothermal activity. The distribution of hydrothermal plumes from a ridge segment to another implies secondary controls such as the presence of fractures and faults along the axis or in the axial discontinuities. We conclude from these results that hydrothermal activity along the SEIR is controlled by magmatic processes at the regional scale and by the tectonics at the segment scale, which influences the type of hydrothermal circulation and leads to various chemical compositions. Such variety may impact global biogeochemical cycles, especially in the Southern Ocean where hydrothermal venting might be the only source of nutrients.
Key Points
Intense and contrasted hydrothermal activity has been evidenced along the South‐East Indian Ridge in the Furious Fifties
Ultramafic circulation is evidenced in the George V FZ, which is the first observation of this type along an intermediate‐spreading ridge
Chemical compositions of the plumes reveal various regional and local controls on the hydrothermal circulation
The article deals with the problem of detecting anomalies in complex dynamical systems under conditions of partial uncertainty inherent in continuous multistage productions. Possible approaches to ...solving the problem of early warning of critical states of the technological process are considered based on the data of continuous monitoring and analysis of the values of diagnostic indicators received during the operation of technological equipment from various sensors. The state of the system is estimated based on short time series formed by sensor readings. Thus, each sensor registers the values of a random process, the characteristics of which are unknown a priori. A set of sensors registers individual values of a multidimensional random process with unknown characteristics. Proposed methods for detecting anomalies in a multi-sensor distributed system allow us to combine the results of measurements obtained from individual sensors. This is necessary in order to draw conclusions about the possible transition of the technological process to a critical state, taking into account the correlation of data in time series.
The purpose of this work is to compare kinematics of small-scale current vortices located near the core-mantle boundary with high-speed anomalies of seismic wave velocity in the lowest mantle ...asso-ciated with the subduction zones. The small-scale vortex paths were early obtained by the authors in the frame of the macro model of the main geomagnetic field sources. Two sources were chosen whose kine-matics are characterized by the complete absence of the western drift and whose paths have a very com-plex shape. Both sources are located in the vicinity of the subduction zones characterized by the extensive coherent regions with increased speed of seismic waves in the lowest mantle. One of them is geographically located near the western coast of Canada and the second one is located in the vicinity of Sumatra. For this study we used the global models of the heterogeneities of seismic wave velocity. It was obtained that the complex trajectories of the vortices is fully consistent with the high-speed anomalies of seismic wave velocity in the lowest mantle. It can be assumed that mixing up with the matter of the lowest mantle, the substance of the liquid core rises along the lowest mantle channel and promotes its further increase. In addition, the volume of oceanic crust, subducted millions of years ago, turned out to be sufficient to penetrate into the liquid core, forming the complex shape restrictions for free circulation of the core liquid.
An important problem of designing distributed systems is to provide a high level of data safety. To solve this problem, two main methods could be considered. The first method is to place the replicas ...of data files into computer network nodes. The second method is based on using a redundancy of data files’ replicas (copies and prehistory’s of replicas) in the network nodes. The paper considers formal models of these two methods that are followed by a brief description of the decision-making process to ensure the preservation of data safety. This process is supported by means of an automated complex consisting of two software modules. These modules solve the problem of the optimal use of the two presented methods, ensuring the data safety in distributed systems. Finally, the application of the proposed approach in the design of logistics and transportation systems is discussed.
The paper proposes an approach to solving the problem of optimal placement of data array replicas in a distributed system. It presents a formal model of a distributed system with unreliable ...communication channels. A system is represented as a graph with coloured arcs. The formulation of the problem of finding the optimal placement of replicas is given. As a criterion for optimization, the minimum response time to a data request is considered. The task solution heuristic algorithm is also proposed in the paper.
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