Active Zone Research Articles

Ca2+ channel and active zone protein abundance intersects with input-specific synapse organization to shape functional synaptic diversity

Synaptic heterogeneity is a hallmark of nervous systems that enables complex and adaptable communication in neural circuits. To understand circuit function, it is thus critical to determine the factors that contribute to the functional diversity of synapses. We investigated the contributions of voltage-gated calcium channel (VGCC) abundance, spatial organization, and subunit composition to synapse diversity among and between synapses formed by two closely related Drosophila glutamatergic motor neurons with distinct neurotransmitter release probabilities (Pr). Surprisingly, VGCC levels are highly predictive of heterogeneous Pr among individual synapses of either low- or high-Pr inputs, but not between inputs. We find that the same number of VGCCs are more densely organized at high-Pr synapses, consistent with tighter VGCC-synaptic vesicle coupling. We generated endogenously tagged lines to investigate VGCC subunits in vivo and found that the α2δ–3 subunit Straightjacket along with the CAST/ELKS active zone (AZ) protein Bruchpilot, both key regulators of VGCCs, are less abundant at high-Pr inputs, yet positively correlate with Pr among synapses formed by either input. Consistently, both Straightjacket and Bruchpilot levels are dynamically increased across AZs of both inputs when neurotransmitter release is potentiated to maintain stable communication following glutamate receptor inhibition. Together, these findings suggest a model in which VGCC and AZ protein abundance intersects with input-specific spatial and molecular organization to shape the functional diversity of synapses.

Ca2+ channel and active zone protein abundance intersects with input-specific synapse organization to shape functional synaptic diversity.

Synaptic heterogeneity is a hallmark of nervous systems that enables complex and adaptable communication in neural circuits. To understand circuit function, it is thus critical to determine the factors that contribute to the functional diversity of synapses. We investigated the contributions of voltage-gated calcium channel (VGCC) abundance, spatial organization, and subunit composition to synapse diversity among and between synapses formed by two closely related Drosophila glutamatergic motor neurons with distinct neurotransmitter release probabilities (Pr). Surprisingly, VGCC levels are highly predictive of heterogeneous Pr among individual synapses of either low- or high-Pr inputs, but not between inputs. We find that the same number of VGCCs are more densely organized at high-Pr synapses, consistent with tighter VGCC-synaptic vesicle coupling. We generated endogenously tagged lines to investigate VGCC subunits in vivo and found that the α2δ-3 subunit Straightjacket along with the CAST/ELKS active zone (AZ) protein Bruchpilot, both key regulators of VGCCs, are less abundant at high-Pr inputs, yet positively correlate with Pr among synapses formed by either input. Consistently, both Straightjacket and Bruchpilot levels are dynamically increased across AZs of both inputs when neurotransmitter release is potentiated to maintain stable communication following glutamate receptor inhibition. Together, these findings suggest a model in which VGCC and AZ protein abundance intersects with input-specific spatial and molecular organization to shape the functional diversity of synapses.

Species limits and hybridization in Andean leaf-eared mice (Phyllotis).

Leaf-eared mice (genus Phyllotis) are among the most widespread and abundant small mammals in the Andean Altiplano, but species boundaries and distributional limits are often poorly delineated due to sparse survey data from remote mountains and high-elevation deserts. Here we report a combined analysis of mitochondrial DNA variation and whole-genome sequence (WGS) variation in Phyllotis mice to delimit species boundaries, to assess the timescale of diversification of the group, and to examine evidence for interspecific hybridization. Estimates of divergence dates suggest that most diversification of Phyllotis occurred during the past 3 million years. Consistent with the Pleistocene Aridification hypothesis, our results suggest that diversification of Phyllotis largely coincided with climatically induced environmental changes in the mid- to late Pleistocene. Contrary to the Montane Uplift hypothesis, most diversification in the group occurred well after the major phase of uplift of the Central Andean Plateau. Species delimitation analyses revealed surprising patterns of cryptic diversity within several nominal forms, suggesting the presence of much undescribed alpha diversity in the genus. Results of genomic analyses revealed evidence of ongoing hybridization between the sister species Phyllotis limatus and P. vaccarum and suggest that the contemporary zone of range overlap between the two species represents an active hybrid zone.

A comparative study of Fibre Bragg Grating for spatially and temporally resolved gas temperature measurements in cold atmospheric pressure plasma jets

Abstract Cold atmospheric pressure plasma jets (CAP-Jet) are successfully used in medical ther-apy for healing of chronic wounds and are widely researched in inactivation of patho-gens and in assisting in cancer therapy. A crucial parameter for these plasma applica-tions is that CAP-Jets operate at temperatures that are tolerable for biological tissues. While tools characterizing the plasma's gas temperature are well developed, there are only a few methods that work with an agreeable limit of uncertainty, complexity and limited perturbation properties to accurately determine that the studied plasma jet operates at tissue tolerable temperatures at all times. In the current work, time resolved measurements of the gas temperature in the effluent of a CAP-Jet are performed using the innovative technique of a Fibre Bragg Grating (FBG), in which the temperature dynamics is measured by a shift of the FBGs resonant wavelength through its thermo-optic coefficient. Comparing with other temporal and spatial diagnostic tools such as thermocouple measurement, Schlieren imaging, and optical emission spectroscopy, we demonstrate reliable calorimetric measurements at different plasma duty cycles. The plasma source maintains tissue tolerable temperatures inside the plasma active zone with values below 35°C at 1 cm distance from the jet nozzle. The calorimetric measure-ments have revealed that the heat power dissipation in comparison to electric energy of our plasma source is at least 50%.

Muscle-fiber specific genetic manipulation of Drosophila sallimus severely impacts neuromuscular development, morphology, and physiology.

The ability of skeletal muscles to contract is derived from the unique genes and proteins expressed within muscles, most notably myofilaments and elastic proteins. Here we investigated the role of the sallimus (sls) gene, which encodes a structural homologue of titin, in regulating development, structure, and function of Drosophila melanogaster. Knockdown of sls using RNA interference (RNAi) in all body-wall muscle fibers resulted in embryonic lethality. A screen for muscle-specific drivers revealed a Gal4 line that expresses in a single larval body wall muscle in each abdominal hemisegment. Disrupting sls expression in single muscle fibers did not impact egg or larval viability nor gross larval morphology but did significantly alter the morphology of individual muscle fibers. Ultrastructural analysis of individual muscles revealed significant changes in organization. Surprisingly, muscle-cell specific disruption of sls also severely impacted neuromuscular junction (NMJ) formation. The extent of motor-neuron (MN) innervation along disrupted muscles was significantly reduced along with the number of glutamatergic boutons, in MN-Is and MN-Ib. Electrophysiological recordings revealed a 40% reduction in excitatory junctional potentials correlating with the extent of motor neuron loss. Analysis of active zone (AZ) composition revealed changes in presynaptic scaffolding protein (brp) abundance, but no changes in postsynaptic glutamate receptors. Ultrastructural changes in muscle and NMJ development at these single muscle fibers were sufficient to lead to observable changes in neuromuscular transduction and ultimately, locomotory behavior. Collectively, the data demonstrate that sls mediates critical aspects of muscle and NMJ development and function, illuminating greater roles for sls/titin.

SEISMIC VULNERABILITY ASSESSMENT OF AN HISTORICAL UNREINFORCED MASONRY BUILDING OF THE XIXTH CENTURY: EL FETH HIGH SCHOOL IN BLIDA, ALGERIA

Schools In Algeria, built in the XIXth and XXth centuries, are not only places of education and learning, but make up a rich cultural heritage of architectural techniques and traditional know-how. However, their seismic vulnerability risks the safety of their occupants. They were built of masonry before seismic regulations were put into place, which increases their sensitivity to seismic hazard. Algeria is situated in a well-known zone of high seismic activity and the risk to these buildings challenges their structural behaviour. This study focuses on an assessment of seismic vulnerability on a specimen built entirely in hollow brick which wonderfully represents this architectural heritage leading to a better understanding of the potential risks for these buildings, at a structural level. Macro element models, using the Tremuri software, are subjected to a non-linear “Pushover” analysis in order to determine the degree of vulnerability and locate the weak sections of the structure which could collapse during seismic action. This study aims to highlight the seismic risks of these types of structures and also offer appropriate guidelines and recommendations that could be of use during a possible rehabilitation or conservation program of this built heritage site.

A geospatial approach to identifying and mapping areas of relative environmental pressure on ecosystem integrity

The influence of increasing anthropogenic pressure on ecosystem integrity, such as land use change, is resulting in many ecosystems experiencing a decline in their ability to maintain balanced functions and services. Identifying and quantifying these pressures over different scales is challenging and thus impacting the achievement or maintenance of key environmental outcomes. In this study, a GIS-based and scalable tool was developed, the Relative Environmental Pressure (REP) Tool, to address these challenges. The REP tool combines an ecosystem integrity conceptual framework with a weighted linear combination analysis to quantify and rank relative environmental pressure across the scale of interest. The REP Tool was developed as an automated Python-based model in a PyCharm working environment using ArcGIS Pro Arcpy scripting. The REP Tool was applied to spatially contiguous geospatial data for the Province of Alberta, Canada and dynamically scaled relative to Hydrologic Unit Codes at level 8 (HUC8) along with regional and sub-regional scale sub-watersheds. Both cumulative and individual relative pressure levels were calculated and mapped for specific ecosystem integrity framework-derived Environmental Pressure Groups (EPGs) including Atmospheric Alteration, Sedimentation, Habitat Alteration, Hydrologic Alteration, and Social Pressure. Data driven Jenks natural breaks were then applied to classify the relative environmental pressures into a nine-level ranking system. The resulting visualization and data outputs from the REP Tool clearly show that the highest cumulative relative environmental pressure values align with the distribution of major population centres, zones of intense agriculture and major industrial activity. These regions reflect the physiography of Alberta with the Rocky Mountain and Boreal natural regions dominated by low relative environmental pressure. As scales become smaller and more refined, the location of the higher relative environmental pressure levels typically become more subdivided with greater spatial precision where higher pressured areas are located. These patterns are repeated when looking at individual EPGs but with enhanced differentiation of pressure as scales are refined. The framework and geospatial science driven approach behind the REP Tool can be universally applied to support enhanced understanding of relative environmental pressures in, or between regions, as well as informing adaptive environmental resource management and monitoring activities.

Corrosion and mechanical properties of Al/Al2O3 composites fabricated via accumulative roll bonding process: Experimental and numerical simulation

With the advancement of science and technology and the construction of metal-based composites (MMC), it became possible to achieve improved properties that were not easily available in an alloy. In fact, with the emergence of such technology, manufacturers were able to adjust the resulting materials according to their needs in such a way as to provide mechanical strength, hardness, corrosion resistance, or other desired properties. These composites were used in various aerospace, automotive, construction, and production industries. Aluminum-based composites are among the structures that have taken an important place in the industry due to their lightweight and high strength. The present study produced bi-alloy aluminum-based 1060/5083 composites fabricated with alumina particles with a Hot ARBp at T = 380 °C. Also, the effect of rolling steps on the roll bonding mechanism is investigated using numerical simulation. As the novelty of this study and for the first time, a bi-alloy 1050/5083 composites reinforced Al2O3 particles via ARB process have been produced and then, potential dynamic polarization in 3.5 Wt% NaCl solution was used to study the corrosion properties of these composites. The corrosion behavior of these samples was compared and studied with that of the annealed aluminum. The study aimed to investigate the bonding behavior between the bi-alloy layers. So, as a result of enhancing influence on the number of ARBp, this experimental investigation revealed a significant enhancement in the main electrochemical parameters and the inert character of the Alumina particles. Reducing the active zones of the material surfaces could delay the corrosion process. Results showed that the corrosion resistance of the sample fabricated after six steps improved more than 100 % in comparison with the initial annealed Al alloy. Also, the average peeling force improved from 45 N to 94 N for the sample fabricated with six steps. Moreover, at a higher number of steps, the corrosion of MMC improved. Moreover, increasing the number of ARBsteps illustrated an improvement in the wear resistance of samples. Finally, the samples' bonding interface, corrosion surface, and peeled surface were investigated using scanning electron microscopy (SEM).

Distinct input-specific mechanisms enable presynaptic homeostatic plasticity.

Synapses are endowed with the flexibility to change through experience, but must be sufficiently stable to last a lifetime. This tension is illustrated at the Drosophila neuromuscular junction (NMJ), where two motor inputs that differ in structural and functional properties co-innervate most muscles to coordinate locomotion. To stabilize NMJ activity, motor neurons augment neurotransmitter release following diminished postsynaptic glutamate receptor functionality, termed presynaptic homeostatic potentiation (PHP). How these distinct inputs contribute to PHP plasticity remains enigmatic. We have used a botulinum neurotoxin to selectively silence each input and resolve their roles in PHP, demonstrating that PHP is input-specific: Chronic (genetic) PHP selectively targets the tonic MN-Ib, where active zone remodeling enhances Ca2+ influx to promote increased glutamate release. In contrast, acute (pharmacological) PHP selectively increases vesicle pools to potentiate phasic MN-Is. Thus, distinct homeostatic modulations in active zone nanoarchitecture, vesicle pools, and Ca2+ influx collaborate to enable input-specific PHP expression.

Regional, local and current forecast of the impact hazard of coal seam sites based on seismic monitoring

Relevance. Insufficient validity of the quantitative criteria of the regional, local and current forecast of the impact hazard of the coal seams being developed, the absence of algorithms linking the use of geophysical and direct geomechanical methods in forecasting. Aim. To develop a comprehensive method of geodynamic forecasting, including determining the extent of an impact-prone area identified by the results of a regional forecast based on the registration data of the GITS seismic monitoring system, for conducting local and current forecasts of impact hazard by regulatory methods. Object. An array of rocks of the excavation column 4-1-5-7 of the Osinnikovskaya mine during mining operations in the zone of a group of tectonic disturbances and the intersection of advanced workings. Methods. Regional geomechanical forecast by the geophysical method of seismic activity registration (GITS system), local (current) forecast by natural electromagnetic radiation methods (Angel-M equipment) and the output of drilling fines. Results. The paper introduces the results of complex studies in the excavation column 4 1-5-7 of the Osinnikovskaya mine to establish a correlation between seismic activity and the parameters of the stress-strain state of the array. The authors have introduced the concept of integral indicators of the considered parameters IF and Ikσ. They take into account the area of the zone for the i-th range according to the complex parameter of seismic activity F and the coefficient of vertical stresses in the roof of the formation Kσ. It is established that the informative value of the integral indicators is almost twice as high as the informative value of the initial parameters. Experimental nomograms и are presented to determine the category "DANGEROUS/NON-DANGEROUS" for the regional forecast of impact hazard according to the GITS seismic monitoring system. The authors developed a general algorithm for predicting the impact hazard during clean-up operations. This algorithm uses an integrated approach that includes a regional forecast for recording seismic activity within the mine field and local forecasting methods, both geophysical and direct, to clarify the boundaries of seismic energy release zones and confirm the category of impact hazard. Thу paper introduces the example of determining the width of the zone of increased seismic energy release in the mine closest to the seismically active zone. The dynamics of the occurrence, development and decrease of the seismic energy release zone in the considered areas in the mine workings is shown. The authors give the examples of the implementation of a local forecast of impact hazard in previously established potentially dangerous areas by methods of recording natural electromagnetic radiation of rocks and by the output of drilling fines.

Diagenetic and hydrothermal events revealed by an Ediacaran dolomite breccia from the Araras-Alto Paraguai basin, southern Amazon Craton

The establishment of extensive carbonate platforms characterized the Ediacaran period during CaCO3 oversaturation events and the exceptional creation of accommodation space associated with the aftermath of the Marinoan glaciation (∼635 Ma). Carbonate deposits in the Araras Group record the early Ediacaran period, stage 1, in the Amazon Craton. The Serra do Quilombo Formation is an intermediate unit characterized by heavily fractured and faulted dolomites, as well as the presence of dolomite-cemented breccias (CB) overlying thick limestone packages associated with diagenetic and hydrothermal modifications. These features are commonly attributed to structurally controlled hydrothermal dolomitization (HTD) and are of significant economic importance as hydrocarbon reservoirs and Mississippi Valley-type (MVT) lead-zinc mineralization hosts. This study aims to unravel the origin of cemented breccias and the diagenetic/burial processes within the unit, focusing on dolomitization processes. Dolomite samples were analyzed using petrographic, scanning electron microscopy, microprobe, micro-Raman, cathodoluminescence, and isotopic analyses (δ13C, δ18O, 87Sr/86Sr) to unravel their burial history. CBs are sub-vertical to sub-horizontal bodies with complex geometries, generally cutting bedding at high angles, indicating hydrofracturing processes related to vertical flows of hydrothermal fluids (hydraulic breccia) and present the typical cockade texture of expansion breccias in dilatational faults. The substitutive matrix RD1 is the main constituent of the Serra Quilombo Formation, its low correlation between δ13C and δ18O (R2 = 0.009), the well-preserved fabric, and the similarity with the isotopic values (C and Sr) documented for Ediacaran carbonates, suggest that the syndepositional dolomitization. The first generation of dolomite cement (DC1) and the last phase of dolomitic cementation (saddle dolomite - SD) occur, filling pores, CBs, and fractures. The cockade texture of the breccias evidences a low precipitation rate or a pause in precipitation between DC1 and SD. Concurrently, DC1 has isotopic signals of δ18O = −4.34 ± 1.32‰ (n = 18) and 87Sr/86Sr = 0.708831 (n = 2), while SD has values of δ18O = −9.57 ± 2.51‰ (n = 15) and 87Sr/86Sr = 0.711464 (n = 3). The large isotopic fractionation between DC1 and SD suggests different dolomitizing fluids. This relationship shows an increase in 87Sr in the fluid as the temperature increases; moreover, the enrichment in 87Sr of the fluid is explained by the interaction of this fluid with rocks from the crystalline basement. Thus, the main conduit for the ascent of this radiogenic fluid would be faults with deep roots spatially close to tectonically active zones. Lastly, the presence of tectonic stylolites cutting cemented breccias and rotated zebra-like strata-bound structures suggests that brecciation occurred before the installation of fragile post-Ordovician transtensional structures, preceding the establishment of Paleozoic Basins on the South American Platform.

μ-Opioid Receptor Modulation of the Glutamatergic/GABAergic Midbrain Inputs to the Mouse Dorsal Hippocampus.

We used virus-mediated anterograde and retrograde tracing, optogenetic modulation, immunostaining, in situ hybridization, and patch-clamp recordings in acute brain slices to study the release mechanism and μ-opioid modulation of the dual glutamatergic/GABAergic inputs from the ventral tegmental area and supramammillary nucleus to the granule cells of the dorsal hippocampus of male and female mice. In keeping with previous reports showing that the two transmitters are released by separate active zones within the same terminals, we found that the short-term plasticity and pharmacological modulation of the glutamatergic and GABAergic currents are indistinguishable. We further found that glutamate and GABA release at these synapses are both virtually completely mediated by N- and P/Q-type calcium channels. We then investigated μ-opioid modulation of these synapses and found that activation of μ-opioid receptors (MORs) strongly inhibits the glutamate and GABA release, mostly through inhibition of presynaptic N-type channels. However, the modulation by MORs of these dual synapses is complex, as it likely includes also a disinhibition due to downmodulation of local GABAergic interneurons which make direct axo-axonic contacts with the dual glutamatergic/GABAergic terminals. We discuss how this opioid modulation may enhance LTP at the perforant path inputs, potentially contributing to reinforce memories of drug-associated contexts.

Synthesis of undoped and mixed binary transition metals (Ni-Co)-doped cupric oxide nanostructures: Structural characteristics, optical behavior, and biological activity

In this work, co-precipitation-assisted undoped and various concentrations (1%, 3%, and 5%) Ni-Co-doped CuO nanostructures have been synthesized to test the biomedical applications. The structure, optical band gap, zone of inhibition width, hemocompatibility, and free radical scavenging activity of the CuO are significantly varied by introducing various concentrations of co-dopants compared to the undoped CuO. The single phase of monoclinic and heterogeneous crystal systems (monoclinic CuO, hexagonal Co, cubic NiO, and Co3O4) for undoped CuO and all Ni-Co-doped CuO samples was identified by the powder XRD tools. Microstructural properties were tuned in each dopant concentration of Ni-Co in the CuO, which confirmed through FE-SEM analysis. Heterogeneous structures (spherical particles/sheet-like particles) were noticed in the HR-TEM studies of 5% Ni-Co-doped CuO nanostructures. Synthesized compounds related to the elements (Cu, O, Co, and Ni) were traced with the help of the EDX and XPS study. The photoabsorption spectra and optical band gap values of the undoped CuO and co-doped CuO samples were significantly varied. Antimicrobial studies of the undoped CuO and Ni-Co co-doped CuO against E. coli and S. mutans bacterial strains were performed, and their outcomes of the zone of inhibition (ZOI) values have been discussed in detail. The synthesized undoped and various concentrations of CuO particles were taken to investigate their compatibility via hemolytic study. Hemolysis results showed that both the synthesized undoped CuO and Ni-Co doped CuO nanostructures are highly hemocompatible. In addition, compatibility natures are varied with increasing concentrations from 1% to 5% Ni-Co dopant in the CuO samples. The DPPH assay was employed to evaluate the antioxidant properties of the synthesized particles by determining their free radical scavenging (FRS) activity percentages. It was observed that Ni-Co-doped CuO exhibited better antioxidant properties than undoped CuO due to the higher FRS percentage.

Paroxysmal dystonia results from the loss of RIM4 in Purkinje cells.

Full-length RIM1 and 2 are key components of the presynaptic active zone that ubiquitously control excitatory and inhibitory neurotransmitter release. Here, we report that the function of the small RIM isoform RIM4, consisting of a single C2 domain, is strikingly different from that of the long isoforms. RIM4 is dispensable for neurotransmitter release but plays a postsynaptic, cell type-specific role in cerebellar Purkinje cells that is essential for normal motor function. In the absence of RIM4, Purkinje cell intrinsic firing is reduced and caffeine-sensitive, and dendritic integration of climbing fibre input is disturbed. Mice lacking RIM4, but not mice lacking RIM1/2, selectively in Purkinje cells exhibit a severe, hours-long paroxysmal dystonia. These episodes can also be induced by caffeine, ethanol or stress and closely resemble the deficits seen with mutations of the PNKD (paroxysmal non-kinesigenic dystonia) gene. Our data reveal essential postsynaptic functions of RIM proteins and show non-overlapping specialized functions of a small isoform despite high homology to a single domain in the full-length proteins.

Ultimate Capacity and Load Transfer Mechanism of Ground Anchors in Granular Soils: State-of-the-Art

The grouted ground anchor is the most used geotechnical element to transfer the tension load from the superstructure or the soil mass in front of the potential failure surface (active zone) to a deeper, efficient soil layer for its reliability and feasibility. It was originally constructed by inserting the tendon, usually a steel strand, into an already drilled borehole filled with cement grout. It was successfully used in the Cheurfas dam in Algeria in (1934). According to the load transfer mechanism, there are two types of ground anchors: tension-type and compression-type. The names of these two types of anchors refer to the developed stresses in the grouted body. The present work presents a literature survey about the load transfer mechanism for both types of anchors: tension and compression embedded in granular soil. Many factors affecting the load transfer mechanism have been reviewed. The main factor affecting the load transfer mechanism is the confining pressure of the borehole. The recently developed methods of estimating the ultimate pullout capacity of the anchor have been reviewed and discussed.

Direct evidence for ultrastructures of the α-synuclein-associated synaptic vesicle pool in presynaptic terminals

SNCA/PARK1 encodes α-synuclein, which is associated with familial Parkinson's disease. Despite its abundance in presynaptic terminals, the aggregation mechanism of α-synuclein and its relationship with Parkinson's disease have not yet been elucidated. Moreover, the ultrastructures of α-synuclein localization sites in neuronal presynaptic terminals remain unclear. Therefore, we herein generated transgenic mice expressing human α-synuclein tagged with mKate2 (hSNCA-mKate2 mice). These mice exhibited normal growth and fertility and had no motor dysfunction relative to their wild-type littermates, even at one year old. α-Synuclein-mKate2 accumulated in presynaptic terminals, particularly between Purkinje cells in the cerebellum and neurons in cerebellar nuclei. α-Synuclein-mKate2 was associated with the presynaptic marker, synaptophysin. In-resin CLEM and immunoelectron or electron microscopy revealed that α-synuclein-mKate2 localized on the surface of synaptic vesicles that were tightly arranged and assembled to form large synaptic pools in the cerebellum with negligible effects on the active zone. These results suggest that α-synuclein-associated ultrastructures in the presynaptic terminals of hSNCA-mKate2 mice reflect the structures of α-synuclein-assembled synaptic vesicle pools, and the size of vesicle pools increased. This transgenic mouse model will be a valuable tool for studying α-synuclein-associated synaptic vesicle pools.

Serviceability fragility assessment of non-seismically designed railway viaducts in Turkey under near-field and far-field earthquakes

While many railway viaducts still in use in Turkish railway networks are located on active fault zones that produced historical destructive earthquakes, they are not seismically designed in accordance to current standards. This study aims to provide a better understanding about the serviceability fragility of such systems by conducting detailed probability-based seismic assessments under near-field and far-field earthquakes. To achieve this, firstly, 3D finite element models of a range of selected viaducts in Turkey were generated based on their original design drawings. The developed FE models were validated by comparing the analytical modal frequencies with the results of in-situ dynamic tests involving a series of acceleration measurements. Nonlinear time history analyses were then carried out under 25 near-field and 25 far-field real three-component ground motion recordings to obtain the seismic response of each selected viaduct. Subsequently, probabilistic seismic demand models were defined using linear regression analysis to determine relationships between engineering demand parameters (EDPs) and ground motion intensity measures (IMs). Peak ground acceleration (PGA), peak ground velocity (PGV) and spectral acceleration at 1.0 s (Sa (1.0)) were used as the IM parameter, while the maximum lateral displacement of the bridge spans for different service velocities defined in the Eurocode was considered as the EDP at serviceability damage state. Finally, analytical fragility curves for all the selected railway viaducts were developed considering maximum damage probability for the IM levels. The results, in general, demonstrate the seismic vulnerability of the existing viaducts in Turkey. It is shown that while at low speed limits the viaducts exposed to far-field ground motions were more vulnerable than those under near-field ground motions, at high speed limits the viaducts subjected to near-field ground motions were more vulnerable. Also, it is seen that reinforced concrete and masonry viaducts are generally more vulnerable to earthquakes than the steel viaducts. The outcomes of this study should prove useful for the seismic risk assessment, loss estimation and rehabilitation of the railway transportation networks in future studies.

Investigation of changes in the cumulative number of magnetic anomalies before and after earthquakes using satellite data

Iran is always at risk of destructive earthquakes due to its location on the Alpine-Himalayan seismic belt. Many significant earthquakes have occurred there so far, which have caused a lot of financial and human losses. The plateau consists of a composite system of collision-oblique transpressive fold-and-thrust mountain belts with active reverse and strike-slip faulting, range-and-basin terrains, active subduction zones, recent volcanic activity, variable crust thicknesses and rigidity, and relatively stable aseismic blocks of different dimensions with low.topographic relief and nearly flat areas., as a result, attention to earthquakes and research in its various fields is necessary and inevitable in Iran. This study investigated Iran’s earthquakes from 2014 to 2021 with a magnitude above 5.5. A total of 30 earthquakes were investigated, of which 21 cases were considered due to solar activities and the simultaneous occurrence of some earthquakes. For this purpose, Swarm Alpha and Swarm Charlie satellite data belonging to the European Space Agency have been used vector magnetic field of all the paths that passed near the place of the earthquake was used between two months before the occurrence and one month after it. First, by performing the first stage of processing for the paths that are close to the earthquake in terms of time, the vivid anomalies caused by the event are identified in the y component of the magnetic field. Then, using these anomalies, a threshold value for the standard deviation is defined for each event so that the anomalies with a higher standard deviation than this threshold value are examined and analyzed. Finally, the occurrence of the studied earthquakes was predicted by fitting the sigmoid function to the cumulative number of anomalies. Because the sigmoid function is not a dynamic function, at the same time, a cubic function has been used to estimate the critical time of the system so that when the sigmoid function cannot fit the data, the cubic function can do this. A first-order curve has also been used to show the proper fit of the data with the sigmoid and cubic functions. And also, C-factor has been used to show the strong compatibility of sigmoid and cubic functions with the cumulative number of anomalies. In the last stage, an analysis has been done under the title of “Confutation analysis” in such a way that the said algorithm is applied to the areas where the earthquake did not occur, and it is expected that the cumulative number of anomalies drawn, will be closer to the linear state than when the earthquake occurred. Using the existing database, 90% of the occurrence of earthquakes studied in this study, pre-indication abnormalities are observed a few hours to a month before the incidence of earthquakes.Also, a Confutation analysis was performed on three cases of earthquakes to show that the obtained results were not random and the change in the cumulative number of magnetic anomalies could be caused by the earthquake.

Analytical Solution of the Mechanical Response of a Shield Tunnel Crossing an Active Ground Fissure Zone

Analytical Solution of the Mechanical Response of a Shield Tunnel Crossing an Active Ground Fissure Zone

Enhanced Performance of the Optimized Dye CF583R in Direct Stochastic Optical Reconstruction Microscopy of Active Zones in Drosophila Melanogaster.

Super-resolution single-molecule localization microscopy (SMLM) of presynaptic active zones (AZs) and postsynaptic densities contributed to the observation of protein nanoclusters that are involved in defining functional characteristics and in plasticity of synaptic connections. Among SMLM techniques, direct stochastic optical reconstruction microscopy (dSTORM) depends on organic fluorophores that exert high brightness and reliable photoswitching. While multicolor imaging is highly desirable, the requirements necessary for high-quality dSTORM make it challenging to identify combinations of equally performing, spectrally separated dyes. Red-excited carbocyanine dyes, e.g., Alexa Fluor 647 (AF647) or Cy5, are currently regarded as "gold standard" fluorophores for dSTORM imaging. However, a recent study introduced a set of chemically modified rhodamine dyes, including CF583R, that promise to display similar performance in dSTORM. In this study, we defined CF583R's performance compared to AF647 and CF568 based on a nanoscopic analysis of Bruchpilot (Brp), a nanotopologically well-characterized scaffold protein at Drosophila melanogaster AZs. We demonstrate equal suitability of AF647, CF568 and CF583R for basal AZ morphometry, while in Brp subcluster analysis CF583R outperforms CF568 and is on par with AF647. Thus, the AF647/CF583R combination will be useful in future dSTORM-based analyses of AZs and other subcellularly located marker molecules and their role in physiological and pathophysiological contexts.