Potential Magnitude Research Articles

Electron Streaming Effect Associated With the Elekta Unity Anterior Imaging Coil

The presence of the static field in magnetic resonance guided radiation therapy (MRgRT) systems, such as the Elekta Unity MR-Linac (MRL), influences charged particle motion due to the Lorentz force in and around patients. Consequently, for the Unity, changes to out-of-field dose (OFD) relative to conventional linacs occur due to the electron streaming effect (ESE) and spiraling contaminant electrons (SCE). This work investigates OFD associated with irradiation of the anterior MR imaging coil, which is in situ for all treatments on the Unity. Film measurements and Monaco simulations were performed to quantify the magnitude of OFD at the superior and inferior ends of the coil as a function of coil tilt relative to the beam direction. The dependence of OFD on field size and the relative electron density (RED) assigned to the coil and surrounding air are reported. The doses at both coil ends were clinically significant, with nearly 23.0% of the Dmax dose to water being recorded for the largest field (8.0 × 22.0 cm2) and 6.8% for the smallest field (3.0 × 3.0 cm2). Monaco simulations of OFD agreed with film within 5.0%, when appropriate calculation conditions were set. OFD decreases as coil tilt is reduced, and there is no evidence of ESE when the coil is horizontal. Clinically, the potential magnitude of cranio–caudal streaming dose from a tilted coil necessitates the use of appropriate shielding. A clinical case involving coil-induced ESE during treatment of a lesion in the right angle is presented. The planning-based investigation revealed that ESE doses associated with the coil and an immobilization vacuum bag can be clinically significant.

Causes, Implications, and Strategies for Project Closeout Delays in Highway Construction

In highway construction, completing projects on time is critical. However, when projects are not completed on time, one of the aspects that is often neglected by the state departments of transportation (DOTs), which causes delays in highway construction, is project closeout. The project closeout phase, if delayed, not only has consequences for transportation agencies and contractors, but also leads to substantial social costs to the public. Despite the potential magnitude of the impact, there is limited knowledge about the factors that cause project closeout delays or about strategies for timely highway construction project closeouts. This study identified the causes that delay highway project closeouts, raises awareness of the implications of delays, and provides recommendations for efficient highway project closeout practices. The research methodology included an extensive literature review, a survey questionnaire (40 state DOTs participating), and case studies of eight state DOTs. The results showed that difficulties in attaining the required documentation, claims and litigations, managing multiple funding sources, a lack of urgency from local utilities/entities, and the lack of sufficient DOT project staff are major factors that delay project closeout. When a highway construction project is not closed out in a timely manner, the DOT can be subject to additional costs, obsolete funding sources, loss of project documentation, loss of staff with project knowledge (through retirement/attrition), and potential adverse impacts on internal and external relationships. The authors provide recommendations for state DOTs to mitigate closeout delays and help ensure timely finalization of highway construction projects.

The effect of aspect changes on Near-Earth Asteroid phase curves

ABSTRACTPhase curves of asteroids are typically considered to depend solely on the scattering properties of airless particulate surfaces and the size of the object being studied. In this study, we demonstrate the additional dependence of phase curves on object shape, rotation pole orientation, and viewing geometry over an apparition. Variations in the phase curve of near-Earth asteroid (159402) 1999 AP10 over its apparition from 2020 July to 2021 January are verified to be due to aspect changes over the apparition. This is achieved through shape modelling of the asteroid and simulation of the phase curve over the apparition. We present simulations of asteroid phase curves over a range of geometries to understand the potential magnitude of this aspect effect, and under which circumstances it can begin to dominate in the phase curves. This dependence on aspect may introduce significant additional uncertainty in the properties derived from phase-curve data. We provide and demonstrate software code to estimate the aspect-related uncertainty in near-Earth asteroid phase curves through simulation and model fitting of a randomly generated sample of ellipsoidal asteroid models over the observed viewing geometry. We demonstrate how ignoring this effect may lead to misleading interpretations of the data and underestimation of uncertainties in further studies, such as those in the infrared that use phase curve derived parameters when fitting physical properties of an asteroid.

On the bias of complete‐ and shifting‐case meta‐regressions with missing covariates

Missing covariates is a common issue when fitting meta‐regression models. Standard practice for handling missing covariates tends to involve one of two approaches. In a complete‐case analysis, effect sizes for which relevant covariates are missing are omitted from model estimation. Alternatively, researchers have employed the so‐called "shifting units of analysis" wherein complete‐case analyses are conducted on only certain subsets of relevant covariates. In this article, we clarify conditions under which these approaches generate unbiased estimates of regression coefficients. We find that unbiased estimates are possible when the probability of observing a covariate is completely independent of effect sizes. When that does not hold, regression coefficient estimates may be biased. We study the potential magnitude of that bias assuming a log‐linear model of missingness and find that the bias can be substantial, as large as Cohen's d = 0.4–0.8 depending on the missingness mechanism.

Microscopic Characteristics of Fault Gouge in Minor-Surface-Rupture Faults: A Case Study in the Longmenshan Fault Zone, Eastern Tibetan

Active faults with potential earthquake magnitude of 6–7 are often incorrectly identified as non-Holocene active faults by traditional geological methods because their co-seismic displacements were very small or even did not reach to surface, and are defined as minor-surface-rupture faults. Geological studies associated with the 2013 Lushan Ms 7.0 earthquake show that the Dachuan–Shuangshi fault (DSF) in the southern segment of the Longmenshan fault zone (LFZ) is a minor-surface-rupture fault. This study focuses on the microstructure and mineral composition of the fault gouge in the DSF using optical microscopy, a scanning electron microscope (SEM), and X-ray diffraction (XRD) methods; then, we compare our results with the previous achievements in the Beichuan–Yingxiu fault (BYF), a major seismogenic fault of the 2008 Wenchuan earthquake, in the middle–northern segment of the LFZ. The results show that the microscopic characteristics of the fault gouge of the DSF are obviously different from those of the BYF in the following aspects: 1) the thickness of the fault gouge produced by one fault event is less than 5 mm; 2) under the microscope, no obvious micro-cracks were examined in surrounding rocks around the fault gouge, and discontinuous micro-cracks and untypical S-C fabrics in the fault gouge were observed; 3) under the SEM, reworked fragments were rare in the fault gouge; 4) the XRD mineral analysis reveals that the total clay content is less than 50%, the content of kaolinite is obviously higher than that of clinochlore, and the content of illite/smectite mixed layer is less than 30%. A contrastive analysis reveals the differences between the microscopic features of the fault gouge of the DSF and the BYF, which are systematical. Therefore, the abovementioned microscopic characteristics identified from the fault gouge in the DSF may be used as auxiliary indicators to identify minor-surface-rupture faults.

Atmosphere-ionosphere coupling induced by volcanoes eruption and dust storms and role of GEC as the agent of geospheres interaction

In this publication we demonstrate how interdependent are our geophysical shells. The large-scale air pollution provided by the intensive volcano eruptions and dust storms from desert areas modify the electric properties of the troposphere creating the low conducting layers and increasing the column resistance for the vertical current flowing between the ionosphere and ground within the Global Electric Circuit (GEC). This modification leads to the local modulation of the ionospheric potential (IP) magnitude and hence to formation of the large-scale irregularities of electron concentration in the ionosphere. To reveal these phenomena, we use the differential GIM TEC mapping procedure showing specific features of the ionosphere reaction. In low latitude and equatorial regions we observe the formation of positive TEC anomalies not only over the area of air pollution but in the magnetically conjugated area as well. We can conclude that these phenomena pose the double error for Precise Point Positioning (PPP). To the danger of aircraft engines destroying is added the increase of navigational PPP errors due to sharp TEC gradients on the borders of the formed large-scale positive irregularities of electron concentration.

AGA Institute Quality Measure Development for the Management of Gastric Intestinal Metaplasia With Helicobacter pylori

AGA Institute Quality Measure Development for the Management of Gastric Intestinal Metaplasia With Helicobacter pylori

Looking back on forward-looking COVID models

SummaryCovid Act Now (CAN) developed an epidemiological model that takes various non-pharmaceutical interventions (NPIs) into account and predicts viral spread and subsequent health outcomes. In this study, the projections of the model developed by CAN were back-tested against real-world data, and it was found that the model consistently overestimated hospitalizations and deaths by 25%–100% and 70%–170%, respectively, due in part to an underestimation of the efficacy of NPIs. Other COVID models were also back-tested against historical data, and it was found that all models generally captured the potential magnitude and directionality of the pandemic in the short term. There are limitations to epidemiological models, but understanding these limitations enables these models to be utilized as tools for data-driven decision-making in viral outbreaks. Further, it can be valuable to have multiple, independently developed models to mitigate the inaccuracies of or to correct for the incorrect assumptions made by a particular model.

Surface Rupture and Slip Distribution along the Zheduotang Fault in the Kangding Section of the Xianshuihe Fault Zone

Abstract The Zheduotang fault (ZDTF) is located in the Kangding section of the Xianshuihe fault zone (XSHF). While the ZDTF plays an essential role in understanding the structural deformation pattern of the Kangding section. Little information is known about the paleoearthquake offsets and slip behavior of the ZDTF. It is therefore essential to analyze the seismic hazards in this area. Using UAV-based photogrammetry, high-resolution satellite images, and field observations, we mapped the surface trace of the fault in detail and measured the horizontal and vertical offsets geomorphological landforms along the fault. The binned cumulative offset probability density (COPD) distribution was calculated to analyze single-event and multievent cumulative offsets. We found that the ZDTF has scarps along its entire ~46 km length, and the offset distributions of its northwestern (NW) and southeastern (SE) sections feature different characteristics. The SE section follows a uniform slip model based on the relationship between cumulative and coseismic offsets. We estimated the maximum potential earthquake magnitudes of the NW section and SE section to be M6.6 and M7.0, respectively, from the measured offsets and empirical formulas. Finally, we discussed the seismic hazard of the ZDTF based on our findings and paleoearthquake data. The NW section is at risk of large earthquakes recurring in the future, whereas the SE section has a low risk of a >M7.0 earthquake recurring in the next 100 years. If these two sections rupture at the same event in the future, the maximum potential magnitude of the ZDTF is M7.2.

Rupture propagation on heterogeneous fault: Challenges for predicting earthquake magnitude

<p indent="0mm">Predicting magnitudes and ground motion of future strong earthquakes on seismogenic faults holds critical implications on seismic hazard zonation and mitigation. Although present approaches to seismic hazard assessment can effectively identify potential regions to host strong earthquakes, it remains extremely challenging to accurately predict future earthquake magnitudes because of various heterogeneities of fault zones, such as fault geometry, medium structure, and frictional properties. In this work, we review a few aspects that play important roles in earthquake rupture propagation and extent, so as to determine the final magnitude of earthquakes. Under the condition of heterogeneous stress distribution on faults, the final magnitude of earthquakes as well as shallow slip distribution depends on where the rupture initiates. As shown in recent numerical models of dynamic rupture simulations, different hypocenters with similar stress level can lead to completely different rupture scenarios, some of which may significantly break the ground whereas others may be buried underground. Such findings shed critical light on seismic hazard preparation, because surface-breaching ruptures can lead to severe damage as vividly evidenced by the 2022 Menyuan <italic>M</italic>_w 6.7 earthquake. To date, we cannot predict future hypocenter locations according to our knowledge of earthquake nucleation and therefore future relevant investigations are highly demanded. Furthermore, the size of seismogenic zone on strike-slip faults controls whether ruptures may become “break-away” to form large earthquakes or stop spontaneously as “self-arresting” of moderate magnitude events. Observations show that aspect ratios between rupture length and down-dip width of dip-slip earthquakes are usually no more than 8. In contrast, the length/width ratios of strike-slip earthquakes may rise to 40 and have a drastic change around the rupture width of <sc>~10 km.</sc> Intrinsic mechanism of such variation in strike-slip earthquakes is attributed to the energy release rate of rupture fronts, which is controlled by the down-dip width. As such, high-resolution constraints on down-dip seismogenic width can be used to estimate the magnitude of future earthquakes on strike-slip faults. Moreover, fault zone structure significantly affects rupture directivity and slip extents. For instance, low-velocity fault zones may promote rupture propagation and thus enlarge the earthquake magnitude. Given the rapid development of seismic observations and seismic imaging techniques, high-resolution fault zone structure can be obtained from data recorded by dense arrays, including nodal network and the newly developed distributed acoustic sensing (DAS) arrays. Integrating with laboratory results of rheology from samples representing crustal rocks, the near-fault high-resolution seismic structure can be converted into rheological properties on faults, which can then be used to outline asperities for future earthquakes. This may provide a critical step to link seismic structure to earthquake potential, as the outlined asperities can be further used to derive rupture scenarios and earthquake magnitudes. To advance our understanding on this front, future work may integrate multiple sources of observations and modeling. Conducting rupture simulations with constraints from geodetic and seismic measurements, as well as laboratory frictional experiments, can be helpful in exploring potential earthquake magnitudes. By considering heterogeneities on faults with reasonable constraints, the numerical models can be useful for investigating the probable hypocenter locations of large earthquakes. Thus, the numerical results may support future near-field observations to improve monitoring of nucleation and development of future large earthquakes. Furthermore, the ground motions generated from the numerical models can also fill the data gap of near-field observations of large earthquakes and provide critical support for physics-based seismic hazard assessment.

Photosynthetic Carbon Assimilation and Electron Transport Rates in Two Symbiont-Bearing Planktonic Foraminifera

Photosymbiosis is one of the key features characterizing planktonic foraminifera; the number of symbiont cells within a single host has been reported to be well over thousands, meaning that photosynthesis by photosymbiosis may be a “hot spot” for primary production, especially in oligotrophic oceans. As microenvironmental conditions around foraminifera are greatly affected by rapid biological activities—such as photosynthesis and respiration—information on the photosynthetic activities of symbionts is essential to interpret the geochemical proxies recorded in foraminiferal tests (e.g., δ13C and δ18O). Recently, active chlorophyll fluorometry has been increasingly employed as a useful tool for immediate estimation of photosynthesis. However, carbon assimilation rates are the only direct indicator of the photosynthetic carbon flux. Therefore, before utilizing active fluorescence methods to understand carbon dynamics in foraminiferal symbiosis, it is necessary to confirm the relationship between the fluorescence-based photosynthetic rate [electron transport rate (ETR)] and carbon assimilation rate (P). Here, these two rates were compared for two species, Trilobatus sacculifer and Globigerinella siphonifera Type II, using 14C-tracer experiments and active fluorometric measurements by fast repetition rate fluorometry. The results showed a significant positive correlation between the P and ETR of the two species, indicating that carbon assimilation can be estimated by the fluorometric method. However, the regression slopes, which represent the apparent electron requirement for carbon assimilation (e–/C), were significantly different in the two species, and were estimated at 26.2 for T. sacculifer and 96.5 for G. siphonifera. These are strikingly high, considering the theoretically and empirically realistic e–/C values. We hypothesized that the high e–/C observed may be due in part to the use of unlabeled respiratory carbon (underestimation of P). A simple mass balance calculation suggests that a significant amount of carbon should derive from the host’s respired CO2, whose contribution is higher in G. siphonifera than in T. sacculifer. Within the context of using test geochemical parameters, such as δ13C, as paleoceanographic proxies, it is important to note that the potential magnitude of the photosynthetic effect varies among species. This attempt to couple ETR and P could comprehensively reveal an interesting perspective on the intimate interactions existing within photosymbiotic systems.

Estimating chikungunya virus transmission parameters and vector control effectiveness highlights key factors to mitigate arboviral disease outbreaks

BackgroundViruses transmitted by Aedes mosquitoes have greatly expanded their geographic range in recent decades. They are considered emerging public health threats throughout the world, including Europe. Therefore, public health authorities must be prepared by quantifying the potential magnitude of virus transmission and the effectiveness of interventions.MethodologyWe developed a mathematical model with a vector-host structure for chikungunya virus transmission and estimated model parameters from epidemiological data of the two main autochthonous chikungunya virus transmission events that occurred in Southern France, in Montpellier (2014) and in Le Cannet-des-Maures (2017). We then performed simulations of the model using these estimates to forecast the magnitude of the foci of transmission as a function of the response delay and the moment of virus introduction.ConclusionsThe results of the different simulations underline the relative importance of each variable and can be useful to stakeholders when designing context-based intervention strategies. The findings emphasize the importance of, and advocate for early detection of imported cases and timely biological confirmation of autochthonous cases to ensure timely vector control measures, supporting the implementation and the maintenance of sustainable surveillance systems.

Impacts of heat stress on global cattle production during the 21st century: a modelling study

Heat stress in animals is one of the major climate change impacts on domesticated livestock raised in both intensive and extensive production systems. At temperatures higher than an animal's thermoneutral zone, heat stress can affect liveweight gain, milk yield, and fertility. Animal welfare may also be negatively affected by heat stress even in the absence of effects on productivity, at least in the short term. We estimated the comparative statics change in the value of cattle milk and meat production from heat stress-induced losses at the global level, using climate scenario outputs for the middle (2045) and end of the century (2085). The loss estimates are based on bioenergetic equations that relate changes in dry matter intake (DMI) to both cold and hot, humid weather. DMI changes were estimated using CMIP6 climate data and linked to a global dataset containing information on livestock production systems, animal numbers, and region-specific and system-specific animal diets. Changes in DMI were converted to changes in milk and meat production and valued using early 20th century world prices (ie, constant 2005 US dollars). For a high greenhouse-gas emission scenario (SSP5-8.5), production losses from heat stress were estimated to amount to $39·94 billion (95% CI 34·39-45·49 billion) per year by the end of the century, or 9·8% of the value of production of meat and milk from cattle in 2005. For a low emission scenario (SSP1-2.6), the value of production losses was $14·89 billion (12·62-16·95 billion) per year, or 3·7% of 2005 value. In both scenarios, losses in most tropical regions were projected to be far greater than they were in temperate regions. Our results highlight the potential magnitude and extent of the adaptation efforts that will be necessary to combat the effects of increasing heat stress on cattle production during this century if food security challenges are to be minimised. Adaptations include switching to more heat-tolerant breeds and provision of shade, ventilation, and cooling systems. CGIAR Trust Fund and bilateral donors.

The significant impact of shape deviations of atmospheric aerosols on light monitoring networks

ABSTRACT Aerosol particles are important modulators of night sky brightness (NSB) due to their manifold impacts on spectral and angular properties of scattered light. The majority of radiative transfer models currently in use are based on rigorous Mie theory for spherical homogeneous particles. This fundamental concept enables significant simplifications in theoretical formulae and numerical modelling. However, as known from many studies, spherical shapes are rare for both natural and anthropogenic aerosols. Therefore, the aim of this paper is to analyse the potential magnitude of the subsequent effect in skyglow modelling assuming that the aerosol particles are of different aspect ratios. The zero-order approximation to tackle the problem is to characterize the non-sphericity by the ratio of the largest to smallest size of an ellipsoidal particle. We use T-matrix formalism to perform light scattering calculations on spheroidal particles of arbitrary size, composition, and orientation in respect to the incident light. Results indicate that the particle-shape impact on NSB can be of significant size leading to both positive and negative amplitudes around the zenith. In the most extreme case, an increase of up to 70 per cent in zenithal luminance was displayed. As a consequence, especially light monitoring devices like the sky quality meter, usually measuring the NSB around the zenith, are particularly influenced by this effect. In summary, the paper underlines both the importance of treating non-spherical aerosols in theoretical modelling of skyglow and also the significance of including atmospheric parameters to analyses of light monitoring networks.

Navigating nature's complexities through Terra MODIS information and downscaled regional climate model: Mainstreaming space-based information for drought disaster risk management

This study utilised Terra MOD13Q1 satellite data to assess drought disaster events and their spatiotemporal patterns over the Free State Province of South Africa between 2001 and 2019 for the summer, autumn, winter, and spring seasons. The study also used high-resolution downscaled climate change projections under three Representative Concentration Pathways (RCP). Three future periods comprising the short (the 2030s), medium (2040s), and long term (2050s) compared to the current period are analysed to understand the potential magnitude of projected climate change-related drought. The study revealed that the year 2001 and 2016 witnessed extreme drought conditions where the drought index is between 0 and 20% across the entire province during summer, while the years 2003, 2004, 2007, and 2015 observed severe drought conditions across the region with variation from one part to the other. The result shows that from −24.5 to −25.5 latitude, the area witnessed a decrease in precipitation (80–120 mm) across the time slice and an increase in the latitude −26° to −28° S for summer seasons, which is more prominent in the year 2041–2050. This study emphasises the substantial spatio-environmental impacts within the province and highlights the associated factors that characterise high drought stress risk, especially on the environment and ecosystems. This study contributes to a disaster risk framework to identify areas for specific research and adaptation activities on drought disaster risk and environmental planning in the study area.

CORR Insights®: Small Random Angular Variations in Pelvic Tilt and Lower Extremity Can Cause Error In Static Image-based Preoperative Hip Arthroplasty Planning: A Computer Modeling Study.

CORR Insights®: Small Random Angular Variations in Pelvic Tilt and Lower Extremity Can Cause Error In Static Image-based Preoperative Hip Arthroplasty Planning: A Computer Modeling Study.

The effects of a group‐deposit prize draw on the step counts of sedentary and low active adults

AbstractApproximately 78% of American adults do not engage in enough physical activity, which is problematic because physical activity is positively correlated with beneficial health outcomes. Contingency management (CM) interventions have been shown to produce clinically significant behavior change across a range of target behaviors and populations, including physical activity. Both prize‐based and deposit‐contract CM interventions work well and decrease the costs associated with intervention, but they can decrease the magnitude of potential payouts. The current study used a prize‐based CM intervention combined with a deposit contract in which each participant deposited money that was pooled in the prize system for all participants. This increased the potential magnitude of reinforcement while keeping costs low for each participant. Four obese and two healthy weight adults participated in the CM intervention, which was introduced according to a single‐case reversal design. Overall, participants took more steps during intervention than during baseline, with four participants regularly taking 10,000 or more steps during intervention.

Systematic study of influencing parameters on the in-situ electrochemical growth of three-dimensional graphene on carbon cloth for supercapacitor applications

A novel two-step electrophoretic deposition/reduction (EPD/red) technique was applied for the electrochemical growth of three-dimensional (3D) graphene on carbon cloth (CC) as electrode material in supercapacitors. The physicochemical and electrochemical characteristics of the electrodes prepared using this approach were compared with those prepared using common electrochemical deposition methods; i.e., galvanostatic and potentiostatic. In order to increase the compatibility of the CC surface with the electrochemical growth of 3D graphene, it was activated using three different methods of chemical, hydrothermal, and electrochemical oxidation. The structural and electrochemical influences of the activation method were followed using different characterization techniques. Further studies were carried out to optimize the potential magnitude and duration of the EPD step and to find the best reduction method as the key parameters influencing the efficiency of the EPD/red technique. All the synthesized electrodes were subjected to physicochemical and electrochemical analyses. The best electrode synthesized using the optimized EPD/red technique provided a high specific capacitance of 364.9 mF cm−2 at 1 mA cm−2 which can be considered as a good candidate for use in carbon-based supercapacitors. Moreover, this electrode can be utilized as a promising conductive substrate for the chemical or electrochemical deposition of pseudocapacitive materials due to its high specific surface area. The symmetric supercapacitor cell prepared based on the best electrode showed a high specific capacitance of 147.4 mF cm−2 at 0.5 mA cm−2, and the capacitance retention of 83% after 2000 cycles of charge/discharge at 5 mA cm−2. It also provided the highest energy density of 20.5 μWh cm−2 at power density of 250 μW cm−2.

A ∼28-kyr Continuous Lacustrine Paleoseismic Record of the Intraplate, Slow-Slipping Fuyun Fault in Northwest China

The Fuyun Fault is a typical intraplate, slow-slipping fault, but has been repeatedly ruptured by surface wave magnitude (Ms) ≥ 8.0 earthquakes. The 11 August 1931 Ms 8.0 Fuyun earthquake resulted in more than 10,000 casualties in the sparsely populated Fuyun area. Cosmogenic 10Be dating of offset landforms produced by prehistoric Ms ≥ 8.0 earthquakes yields an average recurrence interval of 9,700 ± 3,300 years, much longer than previously estimated 2,000–4,500 years, clouding our understanding of the timing and recurrence behavior of past earthquakes originating from the Fuyun Fault. Reflection seismic data reveal widely distributed subaquatic faults in Yileimu Lake, implying high sensitivity of the lake sediments to paleoearthquakes originating from the Fuyun Fault. Two new long sediment cores (Y20A: 267 cm; Y20B: 890 cm) together with previously published two short cores (Y19: 71 cm; Y20: 31.5 cm) from the depocenter and nearshore zone of Yileimu Lake are used for stratigraphic correlations and analyses of sedimentary structures, grain-size distributions, magnetic susceptibility, elemental composition and carbon content. The mass-wasting deposits with underlying soft-sediment deformation structures (SSDS) in the Y20B core indicate six siliciclastic-enriched sandy sediment fluxes from earthquake-triggered landslides of granitic rocks, and isolated SSDS record three additional earthquake-induced in situ deformations. Turbidite-like deposits with sorting indices &amp;gt;3 and Si contents &amp;gt;700 counts per second (cps) are comparable to those of the seismic mass-wasting deposits, and are thus interpreted as seismites from earthquake-induced re-deposition of nearshore sediments. There are a total of 20 seismic events recorded by the Y20B core. Seismic intensity calculation results, combined with historical seismic data, provide potential magnitudes of Ms ≥ 8.0, Ms ≥ 7.0, and Ms ≥ 5.5 for the earthquake-triggered mass-wasting deposits, SSDS, and turbidite-like seismites, respectively, in Yileimu Lake, generally consistent with previously published magnitude thresholds. Radiocarbon dating and stratigraphic correlations constrain the timing of these past earthquakes to ∼28 cal kyr BP. This unique, long lacustrine paleoseismic record suggests a weakly periodic pattern with recurrence intervals between 2,317 and 7,830 years and an average of 5,303 years for potential Ms ≥ 8.0 earthquakes, and reveals an unprecedented high frequency of potential Ms ≥ 7.0 earthquakes originating from the Fuyun Fault in the last 5 kyr, demonstrating the urgent need for an improved assessment of seismic hazards and risks in the Fuyun Fault zone.

Multiple relaxation, reversible electrical breakdown and bipolar conductivity of pyrochlore–type Bi2Cu0.5Zn0.5Ta2O9 ceramics

Cu-doped bismuth zinc tantalate pyrochlore was synthesized for the first time using standard ceramic technology. Electrical properties were investigated by impedance spectroscopy in a wide frequency range of 10 Hz – 1 MHz and a temperature range of 25–450 °C. As a result of modeling the Nyquist curves, the structure of the equivalent circuit of the ceramic is determined. Two mechanisms of ion-migration polarization caused by ionic transfer of copper and oxygen have been discovered. The activation energy of conduction at temperatures above 200 °C was 0.796 ± 0.009 eV. Current-voltage characteristics were investigated in the potential range 0.1–2 V and temperature 150–450 °C. The calculation of the potential barrier on the electrodes showed that at temperatures above ~250 °C, the potential barrier changes sign and magnitude by an order of magnitude from - 150 mV to +10 mV, which is associated with a change in the nature of charge carriers and activation of oxygen conductivity. In ceramics at 400–450 °C, a reversible effect is observed, which is characteristic of electrochromic materials. When measuring the current in the sample at a fixed potential, a transition from a direct current to an increasing current was detected, and then its sharp drop almost to zero. The instant of the onset of the growing current and electrical breakdown, as well as the recovery time of the electrical characteristics of the sample, depend on the applied potential and the temperature of the sample.