Large Magnitude Research Articles

Combining reproductive outcomes predictors and automated estrus alerts recorded during the voluntary waiting period identified subgroups of cows with different reproductive performance potential

The objective was to compare differences in reproductive performance for dairy cows grouped based on the combination of data for predictors available during the prepartum period and before the end of the voluntary waiting period (VWP), automated estrus alerts (AEA) during the VWP, and the combination of both factors. In a cohort study, data for AEA and potential predictors of the percentage of cows that receive AI at detected estrus (AIE), pregnancies per AI (P/AI) for first service, and the percentage of cows pregnant by 150 DIM (P150) were collected from -21 to 49 DIM for lactating Holstein cows (n = 886). The association between each reproductive outcome with calving season (cool, warm), calving-related events (yes, no), genomic daughter pregnancy rate (gDPR; high, medium, low), days in the close-up pen (ideal, not ideal), health disorder events (yes, no), rumination time (high or low CV prepartum and high or low increase rate postpartum), and milk yield (MY) by 49 DIM (high, medium, low) were evaluated in univariable and multivariable logistic regression models. Individual predictors (health disorders, gDPR, and MY) associated with the 3 reproductive outcomes in all models were used to group cows based on risk factors (RF; yes, n = 535 or no, n = 351) for poor reproductive performance. Specifically, cows were included in the RF group if any of the following conditions were met: the cow was in the high MY group, had low gDPR, or had at least 1 health disorder recorded. Cows were grouped into estrus groups during the VWP based on records of AEA (estrus VWP [E-VWP], n = 476 or no estrus VWP [NE-VWP], n = 410). Finally, based on the combination of levels of AEA and RF, cows were grouped into an estrus and no RF (E-NoRF, n = 217), no estrus and RF (NE-RF, n = 276), no estrus and no RF (NE-NoRF, n = 134), and estrus and RF (E-RF, n = 259) groups. Cows received AIE up to 31 d after the end of the VWP, and if they did not receive AIE, they received timed AI after an Ovsynch plus progesterone protocol. Logistic and Cox proportional hazard regression compared differences in reproductive outcomes for different grouping strategies. The NoRF (AIE: 76.9%; P/AI: 53.1%; P150: 84.5%) and E-VWP (AIE: 86.8%; P/AI: 44.8%; P150: 82.3%) groups had more cows AIE and higher P/AI and P150 than the RF (AIE: 64.5%; P/AI: 34.9%; P150: 72.9%) and NE-VWP (AIE: 50.0%; P/AI: 38.9%; P150: 72.1%) groups, respectively. When both factors were combined, the largest and most consistent differences were between the E-NoRF (AIE: 91.3%; P/AI: 58.7%; P150: 88.5%) and NE-RF groups (AIE: 47.3%; P/AI: 35.8%; P150: 69.5%). Compared with the whole population of cows or cows grouped based on a single factor, the E-NoRF and NE-RF groups had the largest and most consistent differences with the whole cow cohort. The E-NoRF and NE-RF groups also had statistically significant differences of a large magnitude when compared with the remaining cow cohort after removal of the respective group. We conclude that combining data for AEA during the VWP with other predictors of reproductive performance could be used to identify groups of cows with larger differences in expected reproductive performance than if AEA and the predictors are used alone.

Mylonite, cataclasite, and gouge: Reconstruction of mechanical heterogeneity along a low-angle normal fault: Death valley, USA

The spectrum of slip behavior in crustal faults generates various rock types that can inform the mechanics of earthquake genesis. However, a single fault exposure may contain evidence of slip at various depths and temperatures due to progressive fault rock formation and overprinting during exhumation. Here, we unravel the spatiotemporal evolution of mechanical transitions along the Boundary Canyon detachment, a low-angle normal fault northeast of Death Valley, USA. Field, microstructural, and geochemical characterizations of fault rocks are compared to existing laboratory experiments and combined with a thermo-kinematic model of fault evolution. Together, these constrain the depths of mechanical transitions along the fault and reveal the evolution of earthquake nucleation zone thickness. Fault exposures from different initial paleodepths passed through the mechanical transitions during footwall exhumation, resulting in overprinting of mylonite by cataclasite and ubiquitous late formation of foliated, illite-rich gouge within the uppermost crust. We present evidence of coseismic low-angle normal fault slip (e.g., injection veins of cataclasite, laminar and grain-inertial fluidization). Coseismic slip likely nucleated at strength contrasts within the fault zone (i.e., contacts between quartzite breccia and calc-mylonite; quartz ribbons and mylonite matrix; breccia and clay gouge) at ≈ 5–9.5 km depth. Observations including mutually overprinting cataclasite/ultramylonite and exposures of pulverized gouge support that dynamic rupture propagated down-dip through the brittle-ductile transition zone (≈10–11 km depth) and up-dip through velocity-strengthening fault patches (≈0–5 km depth). Rapid fault exhumation increased the geotherm, leading to upward advection of the brittle-ductile transition and shallowing/thinning of the earthquake nucleation zone. This process may explain the rarity of large magnitude earthquakes on low-angle normal faults.

Comparison of Supervised versus Self-Administered Stretching on Bench Press Maximal Strength and Force Development.

While there is reported superior effectiveness with supervised training, it usually requires specialized exercise facilities and instructors. It is reported in the literature that high-volume stretching improves pectoralis muscles strength under supervised conditions while practical relevance is discussed. Therefore, the study objective was to compare the effects of volume equated, supervised- and self-administered home-based stretching on strength performance. Sixty-three recreational participants were equally assigned to either a supervised static stretching, home-based stretching, or control group. The effects of 15 min pectoralis stretching, 4 days per week for 8 weeks, were assessed on dynamic and isometric bench press strength and force development. While there was a large magnitude maximal strength increase (p < 0.001-0.023, ƞ2 = 0.118-0.351), force development remained unaffected. Dynamic maximal strength in both groups demonstrated large magnitude increases compared to the control group (p < 0.001-0.001, d = 1.227-0.905). No differences between the intervention group for maximal strength (p = 0.518-0.821, d = 0.101-0.322) could be detected. The results could potentially be attributed to stretch-induced tension (mechanical overload) with subsequent anabolic adaptations, and alternative explanatory approaches are discussed. Nevertheless, home-based stretching seems a practical alternative to supervised training with potential meaningful applications in different settings.

Flood modeling in the Ba River basin using a coupled hydrodynamic model—MIKE FLOOD

AbstractThe problem of flooding in Central Vietnam in general and the lower Ba River in particular is one of the natural disasters that frequently threatens people's lives and socioeconomic development in the region. Especially, climate change is becoming ever more prominent and hotter, making extreme natural disasters more unusual and unpredictable. In this research, MIKE‐FLOOD—a model that connects a 1‐dimensional (1‐D) MIKE 11 Hydrodynamics (HD) model with a 2‐dimensional (2‐D) MIKE 21 HD model—was used to set up. The model was calculated for three floods: (1) flood in October 1993, (2) flood in November 2003, and (3) flood in November 2007; these are floods with high frequency and relatively large magnitude. The results show that the 1993 flood rose and receded quickly. The flood peak inundated an area of 22,600 ha, accounting for 52% of the natural area. The flooded areas deeper than 1, 2, 3, 4, and 5 m were 16500, 11,000, 7000, 4200, and 2200 ha, respectively. In the center of Tuy Hoa city, the flooded area at the time of maximum water level was almost 100%.

Changes in aorta hemodynamics in Left-Right Type 1 bicuspid aortic valve patients after replacement with bioprosthetic valves: An in-silico study.

Bicuspid aortic valve (BAV) is the most common cardiac congenital abnormality with a high rate of concomitant aortic valve and ascending aorta (AAo) pathologic changes throughout the patient's lifetime. The etiology of BAV-related aortopathy was historically believed to be genetic. However, recent studies theorize that adverse hemodynamics secondary to BAVs also contribute to aortopathy, but their precise role, specifically, that of wall shear stress (WSS) magnitude and directionality remains controversial. Moreover, the primary therapeutic option for BAV patients is aortic valve replacement (AVR), but the role of improved post-AVR hemodynamics on aortopathy progression is also not well-understood. To address these issues, this study employs a computational fluid dynamics model to simulate personalized AAo hemodynamics before and after TAVR for a small cohort of 6 Left-Right fused BAV patients. Regional distributions of five hemodynamic metrics, namely, time-averaged wall shear stress (TAWSS) and oscillating shear index (OSI), divergence of wall shear (DWSS), helicity flux integral & endothelial cell activation potential (ECAP), which are hypothesized to be associated with potential aortic injury are computed in the root, proximal and distal ascending aorta. BAVs are characterized by strong, eccentric jets, with peak velocities exceeding 4 m/s and axially circulating flow away from the jets. Such conditions result in focused WSS loading along jet attachment regions on the lumen boundary and weaker, oscillating WSS on other regions. The jet attachment regions also show alternating streaks of positive and negative DWSS, which may increase risk for local tissue stretching. Large WSS magnitudes, strong helical flows and circumferential WSS have been previously implicated in the progression of BAV aortopathy. Post-intervention hemodynamics exhibit weaker, less eccentric jets. Significant reductions are observed in flow helicity, TAWSS and DWSS in localized regions of the proximal AAo. On the other hand, OSI increases post-intervention and ECAP is observed to be low in both pre- and post-intervention scenarios, although significant increases are also observed in this ECAP. These results indicate a significant alleviation of pathological hemodynamics post AVR.

A robust computational framework for variational data assimilation of mean flows with sparse measurements corrupted by strong outliers

A variational framework for the reconstruction of time-averaged mean flows using a sparse set of observations with large magnitudes of noise (referred to as outliers), is presented. The observations constitute a set of point-wise measurements of the mean flow with outliers at certain measurement locations and are incorporated into a numerical simulation governed by the two-dimensional, incompressible Reynolds-averaged Navier-Stokes (RANS) equations with an unknown momentum forcing. This forcing, which corresponds to the divergence of the Reynolds stress tensor, is calculated from a direct-adjoint optimization procedure to reduce the deviation between the measured and estimated mean velocities. ℓ2, ℓ1, Huber, and hybrid loss functions are used to represent the discrepancy in the mean velocity field between the measurements and the predictions. A variety of algorithms are considered to solve the optimization problem with these loss functions and a performance comparison in terms of the quality and physical features of the recovered mean flow is presented. The Huber loss function performed best as it remained robust to strong outliers in the measurements with its ℓ1 contribution and also ensured the uniqueness of the optimal solution with its ℓ2 contribution. Huber loss functions restrict the effect of outliers at the local measurement locations, thereby not affecting the quality of the high-dimensional reconstructed mean flow field. The hybrid loss function, a modified form of the continuous Huber loss function, also recovered the mean flow with high accuracy. We demonstrate the performance of the data assimilation framework for the case of two-dimensional laminar flow around a circular cylinder at Re=100. We then extend the analysis to the case of two-dimensional laminar flow over a backward-facing step at Re=500, to further assess the efficacy and robustness of the data assimilation framework.

Unveiling large charge transfer character of PSII in an iron-deficient cyanobacterial membrane: A Stark fluorescence spectroscopy study.

In this work, we applied Stark fluorescence spectroscopy to an iron-stressed cyanobacterial membrane to reveal key insights about the electronic structures and excited state dynamics of the two important pigment-protein complexes, IsiA and PSII, both of which prevail simultaneously within the membrane during iron deficiency and whose fluorescence spectra are highly overlapped and hence often hardly resolved by conventional fluorescence spectroscopy. Thanks to the ability of Stark fluorescence spectroscopy, the fluorescence signatures of the two complexes could be plausibly recognized and disentangled. The systematic analysis of the SF spectra, carried out by employing standard Liptay formalism with a realistic spectral deconvolution protocol, revealed that the IsiA in an intact membrane retains almost identical excited state electronic structures and dynamics as compared to the isolated IsiA we reported in our earlier study. Moreover, the analysis uncovered that the excited state of the PSII subunit of the intact membrane possesses a significantly large CT character. The observed notably large magnitude of the excited state CT character may signify the supplementary role of PSII in regulative energy dissipation during iron deficiency.

Experimental Investigation on Aerodynamic Performance of Inclined Hovering with Asymmetric Wing Rotation.

This study presents a model experiment method that can accurately reproduce the flapping motion of insect wings and measure related unsteady aerodynamic data in real time. This method is applied to investigate the aerodynamic characteristics of inclined hovering, which distinguishes it from normal hovering by having asymmetric wing rotation during the two half strokes. In the study of the aerodynamic influence of the downstroke rotational angle, it is found that the rotational angle affects lift generation by changing the angle between the wing surface and the horizontal plane in the mid-downstroke. When the wing is almost parallel to the horizontal plane in the mid-downstroke, the vortex structure can maintain structural integrity and a large magnitude, which is conducive to the generation of high lift. In the study of the aerodynamic effect of the upstroke rotational angle, the windward conversion mechanism is proposed to explain the influence of the upstroke rotational angle on the direction and magnitude of thrust. Obtaining the rotational angle that is most conducive to maintaining the flight state of hovering in the present study can provide guidance for the structural design and kinematic control of micro aerial vehicles.

Colchicine for the Prevention of Cardiovascular Disease: Potential Global Implementation.

Targeting traditional cardiovascular risk factors is effective in reducing recurrent cardiovascular events, yet the presence of residual cardiovascular risk due to underlying systemic inflammation is a largely unaddressed opportunity. This review aims to comprehensively assess the evolving role of colchicine as a therapeutic approach targeting residual inflammatory risk in the context of those with coronary artery disease (CAD). Inflammation plays a significant role in promoting atherosclerosis, and targeting anti-inflammatory pathways has the potential to decrease cardiovascular events. Low-dose colchicine (0.5mg/day orally), when added to guideline-directed medical care for CAD, safely decreases major adverse cardiovascular events (MACE) by 31% in stable atherosclerosis patients and 23% in those after recent myocardial infarctions. Meta-analyses of recent randomized control trials further support both the efficacy and safety of colchicine, particularly when added to other standard cardiovascular therapies, including statin therapy. The European Society of Cardiology and other national guidelines endorse the use of low-dose colchicine in patients across the spectrum of CAD. Recently, colchicine was FDA-approved in the United States as the first anti-inflammatory therapy for the reduction of cardiovascular events. In a period of a rising incidence of CAD across the globe, colchicine represents a unique opportunity to decrease MACE due to its large magnitude of benefits and general affordability. However, challenges with drug interactions must be addressed, especially in those regions where HIV, hepatitis, and tuberculosis are prevalent. Colchicine is safe and effective at reducing cardiovascular events across a broad spectrum of coronary syndromes. The ability to simultaneously target traditional risk factors and mitigate residual inflammatory risk marks a substantial advancement in cardiovascular prevention strategies, heralding a new era in the global battle against CAD.

Analysis of impulsive ground motions from February 2023 Kahramanmaraş earthquake sequence

AbstractOn the 6th of February 2023, a large magnitude earthquake (Pazarcık earthquake), $$M_{w}=$$ M w = 7.7, occurred in southeast Türkiye, which caused significant destruction in Türkiye and Syria. Relatively large magnitude aftershocks followed the main shock, and after 9 hours of the main event, another large magnitude earthquake (Elbistan earthquake) occurred, $$M_{w}=$$ M w = 7.6, on a nearby fault. This study analyzes the near-fault seismic signals from earthquakes larger than 5.5 recorded between the main shock and the 31st of March 2023. More than 60 impulsive motions are detected in 3 earthquakes, mostly concentrated in the Pazarcık and Elbistan earthquakes. In the Pazarcık earthquake, many impulsive motions are recorded in near-fault stations with periods of up to 14 s. In contrast, in the Elbistan earthquake, impulsive motions are spatially distributed, with pulse periods of up to 11 s and at distances greater than 150 km. Pulse periods mostly correlate with the magnitude of the earthquake, but pulse probability models do not predict impulsive motions over long distances. The presence of strong impulsive motions in vertical components is also observed. For both earthquakes, peak ground velocities (PGVs) are larger than predicted by ground motion prediction equations. The observation of long-period, large amplitude signals may indicate the presence of a directivity effect for both earthquakes. In some stations, spectral periods exceed the 2018 Turkish building design codes for long periods ($$\ge$$ ≥ 1 s).

Machine learning technique in the north zagros earthquake prediction

Studying the changes in seismicity, and the potential of the occurrences of large earthquakes in a seismic zone is not only extremely important from the aspect of seismological research, but it is additionally significant in the decisions of crisis management. Since, nowadays Machine learning techniques have proven the high ability for analyzing information, and discovering the relations among the parameters, in this research were tested some of these techniques for the earthquake prediction. For analysis, the north Zagros seismic catalogue was selected. A region that is an active seismic zone, and large cities are located there. Moreover, nine seismic parameters were used to study the possibility of large earthquake prediction for 1 month using three different Machine Learning (ML) techniques (Artificial Neural Network (ANN), Random Forest, and Support Vector Machine (SVM)). The accuracy of prediction models was evaluated using four different statistical measures (recall, accuracy, precision, and F1-score). The results showed that the (ANN) method is more accurate than other methods. Based on three investigated methodologies, greater accuracy results have been produced to forecast the earthquakes with bigger scale earthquakes about the completeness of the seismic catalogue in large magnitude. These achievements promise the possibility of successful prediction in a short period, which is hopeful for better crisis management performance.

Understanding Challenges Women Face in Flood-Affected Areas to Access Sexual and Reproductive Health Services: A Rapid Assessment from a Disaster-Torn Pakistan.

According to the Global Climate Risk Index, Pakistan is ranked as the fifth-most vulnerable country to climate change. Most recently, during June-August 2022, heavy torrential rains coupled with riverine, urban, and flash flooding led to an unprecedented disaster in Pakistan. Around thirty-three million people were affected by the floods. More than 2 million houses were damaged, leaving approximately 8 million displaced and approximately 600,000 people in relief camps. Among those, 8.2 million women and 16 million children are the worst affected, with many requiring urgent medical and reproductive healthcare. To plan an efficient healthcare program and a climate-resilient health system, it is crucial to understand the issues that the affected people face during floods. Methodology. This rapid assessment included the population in the most severely affected districts across the four provinces of Pakistan. A mixed methods approach using qualitative and quantitative techniques was utilized. A total of 52 qualitative, in-depth interviews were conducted with community-level healthcare providers, national and provincial government departments, and development partners involved in relief activities. Using a structured questionnaire, the quantitative cross-sectional survey was conducted with a final sample of 422 women, married and unmarried (15-49 years old), residing in the relief camps in the flood-affected areas. The outcome variable of the survey was the access to sexual and reproductive health services faced by the women in the flood-affected districts. Data collection took place four months postfloods during Nov-Dec 2022, while the data analysis was conducted between Dec 2022 and Jan 2023. The quantitative data was analyzed using SPSS (Statistical Package for the Social Sciences) version 20, and qualitative data was analyzed using NVivo 12. Ethical consent was sought from all the participants. Ethical approval was also sought from the ethics committee of the Health Services Academy, Government of Pakistan. The findings indicated that, overall, all the provinces were unprepared for a calamity of such a large magnitude. Access to services and health data reporting from the flood-affected areas was challenging mainly due to a shortage of trained health workforce because of the displacement of a large volume of the health workforce. Overall, equipment, medicines, supplies, and food were scarce. Women residing in the camps were markedly affected, and 84% (375) were not satisfied with the flood relief services provided to them. The floods impacted their monthly income as 30% (132) of respondents started depending on charity postfloods. Almost 77% (344) reported limited access to sexual and reproductive health services and had yet to receive sanitary, hygiene, and delivery kits, while 69% (107 out of 154) of girls stopped schooling postfloods. Almost 77% (112) of the married women reported having a child less than one year of age. Yet, only 30% (44 out of 144 currently married women) were using any form of family planning method-damage to the health facilities affected access to overall maternal care services. The findings concluded that there was no planning for sexual and reproductive health services in the flood-affected areas. Several barriers were identified. The government and development partners needed to prepare to cater to women's needs during the floods. The findings highlight the need for collaborative efforts between the government, civil society, and development partners to address the challenges faced in disaster management and strengthen disaster management capacity.

Interannual Lightning Variability within the TRMM LIS Dataset Using an ENSO Perspective

Abstract The Tropical Rainfall Measuring Mission (TRMM) Lightning Imaging Sensor (LIS) was used to investigate interannual variability of lightning from 1998 to 2014 within the 38°S–38°N range. Previous studies have indicated that the El Niño–Southern Oscillation (ENSO) phenomenon is one significant contributor to interannual lightning variability, potentially the dominant mechanism on the global scale. This period of 16 years contained four warm- (El Niño), eight cold- (La Niña), and four neutral-phase ENSO years based on the oceanic Niño index. Large magnitude lightning anomalies were found during the warm phase of ENSO, with mean warm-phase anomalies of &gt;10 flashes (1000 km)−2 min−1 in north-central Africa and Argentina. This includes a +35 flashes (1000 km)−2 min−1 anomaly in Argentina during the 2009 El Niño. In general, large-scale anomalies of thermodynamic properties and upper-atmospheric vertical motion coincided with the lightning anomalies observed in both Africa and South America. The anomaly over north-central Africa, however, was characterized by a 6-week shift in the annual lightning maximum with the warm phase, a result of the more complex environmental response to ENSO over the Sahel. The most consistent ENSO anomalies with appreciable lightning were found in southeastern Africa, northwestern Brazil, central Mexico, and the southern Red Sea. Of these, all but the Mexico region had enhanced lightning with the cold phase and suppressed lightning with the warm phase.

Double Diffusion of Blood-Gold Carreau Nanofluid Using Partial Slip

The investigation of double diffusive convection for the blood-gold Carreau nanofluid over an upper horizontal surface of a paraboloid of revolution (uhspr) with partial slip is the subject of this paper. It is assumed that the Carreau nanofluid corresponding to an infinite shear-rate is zero. The regulating PDE’s are converted into ODE’s by using the appropriate transformations. The reduced system of ODE’s is solved by using the RK-4th order method with the help of collocation formula bvp4c defined in Matlab software. The numerical computations for emerging parameters on the velocity, temperature, concentration, partial slip, etc. have been investigated for both shear-thinning and shear-thickening. The outcome of the study reveals that the velocity increases and temperature decreases with the rise in buoyancy parameters in both respects of small value of partial slip λ = 0.1 and large magnitude of partial slip λ = 2 while dual effects on the concentration gradient is observed at the boundary and free stream. Furthermore, these findings are in perfect agreement with previously published work on special cases.

Seismic Constraints on Hydrothermal Circulation and Magmato‐Tectonic Interactions Beneath Lucky Strike Volcano, Mid‐Atlantic Ridge

AbstractThe Lucky Strike volcano is the central edifice of the Lucky Strike segment on the slow spreading Mid‐Atlantic Ridge. The volcano summit hosts one of the largest known deep‐sea hydrothermal fields, and overlies an axial magma chamber (AMC) whose summit reflector lies 3–3.8 km beneath the seafloor. We present a 12‐year microearthquake catalog beneath the volcano, which we constructed using data collected from 2007 to 2019 as part of the EMSO‐Azores observatory. The catalog reveals continuous low magnitude seismicity (85% with ML &lt; 0), focused mainly north‐northwest of the hydrothermal field and 0–2 km above the AMC reflector. Focal mechanisms estimated only from the 2010–2011 deployment show a mixture of thrust, normal and strike/slip faulting mechanisms. We propose that the observed microearthquake activity is due to thermal cracking, tectonic cracking, and possible small dike injections occurring at the base of hydrothermal downflow zones. We document a ∼800 m eastward shift of the seismicity sometime during a catalog gap from June 2013 to April 2015, accompanied by a change in the seismicity pattern from a patch just above the AMC to a more vertically aligned structure. We also identify several higher seismicity periods, often including relatively large magnitude events (ML &gt; 0.8). We interpret the spatio‐temporal variations in seismicity patterns and the correlation between larger magnitude events and higher seismicity periods to indicate that the hydrothermal domain is a dynamic interface, where the variations are caused by changes in permeability and/or temperature induced by tectonic and small episodic melt injections.

Development and Initial Validation of the Cultural Match Scale for Higher Education Settings

Cultural mismatch theory of inequality and associated research indicates that a mismatch between independent cultural norms of institutions of higher education and students’ interdependent backgrounds account for disparities in academic achievement for students from historically underrepresented groups. Despite growing interest in interventions to reduce cultural mismatch, there was not yet a comprehensive measure of cultural match. We developed and validated the Cultural Match Scale (CMS) composed of 24 Likert-scale items. The CMS measures Navigation of Institutional Culture, Connection to Community, and Connection to Institutional Values. Data from 858 participants were utilized to obtain validity and reliability evidence. Three factors with a general method factor for all negatively worded items showed the best fit. Consistent with the prior findings, relationships with four criterion measures showed medium to large magnitudes of correlations. Reliability was acceptable to excellent levels. The use of the CSM was discussed along with the needs for future research.

Episodic eruptions of young accreting stars: the key role of disc thermal instability due to Hydrogen ionization

ABSTRACT In the classical grouping of large magnitude episodic variability of young accreting stars, FU Ori type objects (FUORs) outshine their stars by a factor of ∼100, and can last for up to centuries; EX Lupi type ones (EXORs) are dimmer, and last months to a year. A disc Hydrogen ionization thermal instability (TI) scenario was previously proposed for FUORs but required unrealistically low disc viscosity. In the last decade, many intermediate-type objects, for example, FUOR-like in luminosity and spectra but EXOR-like in duration were found. Here, we show that the intermediate-type bursters Gaia20eae, PTF14jg, Gaia19bey, and Gaia21bty may be naturally explained by the TI scenario with realistic viscosity values. We argue that TI predicts a dearth (desert) of bursts with peak accretion rates between 10−6 ${\rm {\rm M}_{\odot }}$ yr−1$\lesssim \dot{M}_{\rm burst} \lesssim 10^{-5}$ ${\rm {\rm M}_{\odot }}$ yr−1, and that this desert is seen in the sample of all the bursters with previously determined $\dot{M}_{\rm burst}$. Most classic EXORs (FUORs) appear to be on the cold (hot) branch of the S-curve during the peak light of their eruptions; thus TI may play a role in this class differentiation. At the same time, TI is unable to explain how classic FUORs can last for up to centuries, and overpredicts the occurrence rate of short FUORs by at least an order of magnitude. We conclude that TI is a required ingredient of episodic accretion operating at R ≲ 0.1 au, but additional physics must play a role at larger scales. Knowledge of TI inner workings from related disciplines may enable its use as a tool to constrain the nature of this additional physics.

Development of a method for measuring pulse currents of large magnitude

The paper presents the results of a study on the search for correct methods for measuring a high-value current pulse, which will be used to conduct research on the electroplastic effect. The electroplastic effect is the effect of electric current pulses on the plastic flow of metals. Electroplastic metal forming technology is a relatively new metal forming process that is energy efficient, environmentally friendly and versatile. In particular, it can be used to process metals or alloys that are difficult to process using conventional manufacturing processes. For the experimental study of the electroplastic effect, it became necessary to measure pulse currents of large magnitude, not only in amplitude, but also in the shape of the pulse. The pulsed current causes the formation of an alternating electromagnetic field near the conductors, so it can be measured with a Rogovsky current transformer. The results of the work present a schematic electrical diagram and a photograph with the appearance of an experimental installation for the study of the electroplastic effect. The results of measurements of the current value, the voltage drop on the sample and the dependence of the peak voltage values on the sample on the peak current value are shown. After making calculations and renormalising the data for the voltage drop on the sample according to the peak value of the current obtained on the transformer, the authors obtained the desired current values. The error of this method is estimated by calculating the total capacitance of capacitors, which does not exceed 2%.

Soil organic carbon increase via microbial assimilation or soil protection against the priming effect is mediated by the availability of soil N relative to input C

Labile C inputs into soils will be partially transformed into soil organic carbon (SOC) through microbial assimilation or physicochemical protection as such mineral-organic interactions and soil aggregation. The C inputs may stimulate the decomposition of native SOC, inducing a phenomenon known as the priming effect. Increasing C inputs may increase SOC content, yet the relative role of these mechanisms in controlling the magnitudes of SOC increase among soils remains unclear. Four soils differing in microbiology and N content were incubated with 13C-labeled glucose at the amounts of 0.5 (G0.5), 1.0 (G1.0), and 2.0 (G2.0) g C kg−1 soil for 48 days. The objectives of this study were 1) to quantify the fates of added glucose-C, the priming effect, and the changes in SOC and mineral N contents after the incubation, and 2) to identify the main mechanisms for SOC increase with the increased amount of C input and the effects of initial soil N availability and microbial composition. 13C isotope probing showed that 19 to 26 % and 37 to 96 % of added glucose were utilized for microbial respiration and growth, respectively, after the incubation in all soils, with the glucose-C use efficiency ranging from 30 to 60 %. The remaining accounted for 4 to 37 % in all cases except for UltisolHN at G1.0 and G2.0 (–23 % and −2%), which was confirmed as the fraction protected in soil or re-utilized by microbes via acid extraction. The soil-protected glucose-C was higher, while glucose-C use efficiency was lower with the increased amount of added glucose only in the soils with low N. Glucose addition induced a positive priming effect, a SOC increase, and a mineral N loss irrespective of soil type and addition amount. Glucose addition increased the cumulative fungal biomass in all cases and the cumulative bacterial biomass only at G2.0 in all soils and at G1.0 in the high-N soils. It increased the final fungal necromass only at G0.5 in MollisolLN and UltisolHN and at G2.0 in MollisolHN and the final bacterial necromass in all cases except for the low-N soils and UltisolHN at G2.0. With the increased amount of added glucose, the SOC content increased linearly and the priming effect and fungal biomass increased non-linearly, with larger magnitudes in the soils with lower N. These results indicated that glucose was quickly protected after addition and remained in the soil until soil N became a limiting factor for microbial utilization. The availability of soil N relative to input C mediated microbial growth and its controls over SOC change via the soil protection and priming effects. The carbon sequestration potential with increased input of dissolved substrates as such glucose e. g. through root exudation was likely larger in soils with lower fertility due to reduced substrate-C use efficiency and increased effect of soil protection despite an increased priming effect. Further studies are needed on more substrate types as they affect substrate-C use efficiency and soil protection mechanisms.

Spatial migration of temporal earthquake clusters driven by the transfer of differential stress between neighbouring fault/shear-zone structures

Uncertainty concerning the processes responsible for slip-rate fluctuations associated with temporal clustering of surface faulting earthquakes is a fundamental, unresolved issue in tectonics, because strain-rates accommodated by fault/shear-zone structures are the key to understanding the viscosity structure of the crust and seismic hazard. We constrain the timing and amplitude of slip-rate fluctuations that occurred on three active normal faults in central Italy over a time period of 20–30 kyrs, using in situ36Cl cosmogenic dating of fault planes. We identify five periods of rapid slip on individual faults lasting a few millennia, separated time periods of up to 10 millennia with low or zero slip-rate. The rapid slip pulses migrated across the strike between the faults in two waves from SW to NE. We replicate this migration with a model where rapid slip induces changes in differential stress that drive changes in strain-rate on viscous shear zones that drive slip-rate variability on overlying brittle faults. Earthquakes increase the differential stress and strain-rate on underlying shear zones, which in turn accumulate strain, re-loading stress onto the overlying brittle fault. This positive feedback produces high strain-rate episodes containing several large magnitude surface faulting earthquakes (earthquake clusters), but also reduce the differential stress on the viscous portions of neighbouring fault/shear-zones slowing the occurrence of large-magnitude surface faulting earthquakes (earthquake anticlusters). Shear-zones on faults experiencing anticlusters continue to accumulate viscous strain at a lowered rate, and eventually this loads the overlying brittle fault to failure, initiating a period of rapid slip through the positive feedback process described above, and inducing lowered strain-rates onto neighbouring fault/shear-zones. We show that these patterns of differential stress change can replicate the measured earthquake clustering implied by the 36Cl data. The stress changes are related to the fault geometry in terms of distance and azimuth from the slipping structure, implying that (a) strain-rate and viscosity fluctuations for studies of continental rheology, and (b) slip-rates for seismic hazard purposes are to an extent predictable given knowledge of the fault system geometry.