Contrasting Behavior Research Articles

Sex-dependent effects of angiotensin II type 1 receptor blocker on molecular and behavioral changes induced by single prolonged stress

Post-traumatic stress disorder (PTSD) is a neuropsychiatric disorder that not only entails alterations in fear behavior and anxiety but also includes neuroendocrine dysfunctions involving the hypothalamic pituitary adrenal (HPA) axis and the renin-angiotensin system. Recent preclinical studies demonstrate that activation of the angiotensin type 1 receptor (AT1R) in the paraventricular region of the hypothalamus (PVR) promotes anxiety-like behaviors and enables microglia proliferation. An increase in microglia and anxiety-like behavior also occurs in the PTSD animal model single-prolonged stress (SPS). In the present study, we tested whether AT1Rs contribute to the effects of SPS on behavior and microglia in brain structures important for HPA axis regulation and fear behavior. To test this, male and female animals were exposed to SPS and then given the oral AT1R antagonist candesartan beginning one week later. Candesartan did not alter auditory fear conditioning or extinction in SPS-exposed male or female animals. However, we found that the male animals exposed to SPS showed increased anxiety-like behavior, which was reversed by candesartan. In contrast, neither SPS nor candesartan altered anxiety-like behavior in the female animals. At the molecular level, SPS increased the cellular expression of AT1Rs in the PVR of male animals and candesartan reversed this effect, whereas AT1Rs in the PVR of females were unaltered by either SPS or candesartan. Iba1-expressing microglia increased in the PVR after SPS exposure and was reversed by candesartan in both sexes suggesting that SPS stimulates AT1Rs to increase microglia in the PVR. Collectively, these results suggest that the contribution of AT1Rs to the molecular and behavioral effects of SPS is sex-dependent.

Defect Thermodynamic Modeling of Triple Conducting Perovskites (La,Ba)Fe1-xMxO3-δ for Proton-Conducting Solid-Oxide Cells

Density functional theory (DFT) based modeling was performed to investigate the defect energetics of the proton conducting oxides BaFe1-xMxO3-δ (with M=Zr, Y, and Zn at the B-site). High-throughput defect modeling was carried out to obtain the defect energetics ensembles as a function of B-site x (0 – 0.25) and oxygen δ (0 – 0.5) compositions for assessment of oxygen vacancy formation (Evac) and hydration reaction (Ehyd) energies in complex defect-dopant configurations. The modeling effort aims to elucidate the complex coupling among oxygen vacancies, the protons and metal dopants in various concentrations and their combined effect upon defect energetics in BaFe1-xMxO3-δ perovskite. This information complements the current experimental measurements with essential data related to the energetics of various defect configurations that can play a role in solid-oxide-cell (SOC) applications. Preliminary results among more than 3,000 configurations investigated are summarized in Figure 1. All calculations were performed with the Perdew-Burke-Ernzerhof (PBE) functional in charge neutral 2 × 2 × 2 perovskite supercells. An effective Hubbard Ueff correction of 4 eV was applied to the Fe 3d shell, with all the Fe atoms being in a high-spin state and having a ferromagnetic ordering. Stability analysis of each of the BaFe1-xMxO3-δ systems investigated at specified x and δ composition values reveals that the oxygen vacancy (VO) is energetically unfavorable when placed adjacent to the M dopant. Overall, the Fe-VO-Fe configurations are identified to be more stable than the Fe-VO-M and M-VO-M configurations, while one with a M-VO-M cluster arrangement is the least stable. Such a short-range ordering leads to the blocking of the oxygen vacancy migration toward the oxygen sites around the M dopant, whereas the proton hopping between the oxygens around the M dopants is energetically not hindered. Based on the stability of various defect-dopant configurations of the BaFe0.75M0.25O2.875 systems with or without hydration, it is revealed that the stability range of analogous configurations with varying dopant types can be an indicator of the defect-dopant ordering strength and can be correlated with the ionic radii of the dopants in the BaFe1-xMxO3-δ systems.Taking the energy of the most stable BaFe1-xMxO3-δ structures at various x and δ values analyzed as representative for the respective compositions, the corresponding derivations of the Evac and Ehyd energies as a function of δ (and x) are summarized in Figures 1(a) and 1(b), respectively. Overall, the results indicate a stronger oxygen non-stoichiometry (δ) dependence in the Evac values of the BaFeO3-δ and BaFe1-xMxO3-δ systems (M=Zr, Y, and Zn at x=0.125 and x=0.25), whereas the Ehyd data exhibit a much weaker δ dependence. This contrasting behavior in the δ dependences between Evac and Ehyd values may be attributed to the charge transfer characteristics of the oxygen vacancy formation reaction, which is associated with the Fe 3d and the O 2p energy levels of the materials at various δ values while the charge transfer involved in the hydration reaction is relatively minimal. The effect of dopant concentration (x) further shows an opposite trend in the Evac values vs. x with the dopant types, with an increase of Evac upon increasing the Zr doping concentration and a decrease of Evac upon increasing the Y and Zn doping content. Due to the strong oxygen non-stoichiometry dependence in the Evac values, the results indicate an increased proton affinity of the BaFe1-xMxO3-δ oxides. Further assessments of the Evac and Ehyd data on δ values and their impact upon the defect equilibria of the BaFe1-xMxO3-δ systems under the SOC operating conditions will be discussed. Disclaimer This project was funded by the U.S. Department of Energy, National Energy Technology Laboratory, in part, through a site support contract. Neither the United States Government nor any agency thereof, nor any of their employees, nor the support contractor, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Figure 1

Multi-objective design optimization of bioresorbable braided stents

Background and objectivesBioresorbable braided stents, typically made of bioresorbable polymers such as poly-l-lactide (PLLA), have great potential in the treatment of critical limb ischemia, particularly in cases of long-segment occlusions and lesions with high angulation. However, the successful adoption of these devices is limited by their low radial stiffness and reduced elastic modulus of bioresorbable polymers. This study proposes a computational optimization procedure to enhance the mechanical performance of bioresorbable braided stents and consequently improve the treatment of critical limb ischemia. MethodsFinite element analyses were performed to replicate the radial crimping test and investigate the implantation procedure of PLLA braided stents. The stent geometry was characterized by four design parameters: number of wires, wire diameter, initial stent diameter, and braiding angle. Manufacturing constraints were considered to establish the design space. The mechanical performance of the stent was evaluated by defining the radial force, foreshortening, and peak maximum principal stress of the stent as objectives and constraint functions in the optimization problem. An approximate relationship between the objectives, constraint, and the design parameters was defined using design of experiment coupled with surrogate modelling. Surrogate models were then interrogated within the design space, and a multi-objective design optimization was conducted. ResultsThe simulation of radial crimping was successfully validated against experimental data. The radial force was found to be primarily influenced by the number of wires, wire diameter, and braiding angle, with the wire diameter having the most significant impact. Foreshortening was predominantly affected by the braiding angle. The peak maximum principal stress exhibited contrasting behaviour compared to the radial force for all parameters, with the exception of the number of wires. Among the Pareto-optimal design candidates, feasible peak maximum principal stress values were observed, with the braiding angle identified as the differentiating factor among these candidates. ConclusionsThe exploration of the design space enabled both the understanding of the impact of design parameters on the mechanical performance of bioresorbable braided stents and the successful identification of optimal design candidates. The optimization framework contributes to the advancement of innovative bioresorbable braided stents for the effective treatment of critical limb ischemia.

Cardiovascular Applications of Photon-Counting CT Technology: A Revolutionary New Diagnostic Step.

Photon-counting computed tomography (PCCT) is an emerging technology that can potentially transform clinical CT imaging. After a brief description of the PCCT technology, this review summarizes its main advantages over conventional CT: improved spatial resolution, improved signal and contrast behavior, reduced electronic noise and artifacts, decreased radiation dose, and multi-energy capability with improved material discrimination. Moreover, by providing an overview of the existing literature, this review highlights how the PCCT benefits have been harnessed to enhance and broaden the diagnostic capabilities of CT for cardiovascular applications, including the detection of coronary artery calcifications, evaluation of coronary plaque extent and composition, evaluation of coronary stents, and assessment of myocardial tissue characteristics and perfusion.

Long-term estimation of glacier mass balance using geospatial techniques in Western Himalayas, Ladakh, India

All glaciers are subject to mass fluctuations in the current context of climate change. For daily requirements like food, drink, irrigation, and the generation of hydroelectric power, these glaciers provide water to important basins including the Indus, Ganga, and Brahmaputra. Changes in glacier patterns are a blatant sign of local climate variability. Monitoring of glaciers requires long-term studies on glacier dynamics. Himalayan glaciers, because of their disposition in a complex topographic setting and inaccessible terrain render difficulty in the glacier observations in a continuous mode. Glacier mass fluctuations can be associated with glacier area shrinkage or expansion and concomitant snout shift. In the current study, two adjoining glaciers of different sizes, Pensilungpa and Drang Drung glaciers in the Zanskar Valley, Ladakh, India are selected. The period of the study was taken between the years 2000–2022. Earlier studies used a single day per year Accumulation Area Ratio (AAR) method to compute mass balance, which had limitations due to snow cover variability. The present study calculated and averaged all the AAR values for cloud-free images per year during the peak ablation period (mid-July to early September). Digital Elevation Model (DEM) difference technique was also employed for computing the mass budget between 2000 and 2021 b y utilizing two-time period DEMs. It was revealed that in the case of the AAR method, the Pensilungpa glacier showed 7 years of positive and 16 years of negative mass balance. The years 2003–2005 and 2011 to 2016 were depicted with negative mass balance with the highest value up to −0.752-m water equivalent (m.w.e.) for the year 2015. It has negligible areal fluctuations ranging from 0.01 to 0.6 km2. Drang Drung Glacier has shown 12 years of positive and 11 years of negative mass balance. The years 2002–2004 and 2009 to 2012 were depicted with positive mass balance with the highest value up to 0.305 m. w.e. Except, for the year 2009–2012 (areal increment ∼ 2.65 km2), years 2013–2015 showed a negative mass balance with negligible areal fluctuations. Mass balance estimation using DEM differencing method revealed an average estimated mass balance of −0.03 m. w.e. For Pensilungpa glacier though, it is 0.08 m. w.e. For Drang Drung glacier which shows good matches with the mass balance estimated using AAR method in m. w.e. Such contrasting behavior of mass balance suggests higher sensitivity of smaller glaciers to climate change.

Evolutionary motives in employees’ knowledge behavior when being envied at work

PurposeKnowledge transfer is a crucial ingredient of employee innovation, yet affective work events may disrupt knowledge flow among employees. This study aims to investigate a previously overlooked, yet frequently occurring affective work experience, namely, that of being envied, and examine how perceptions of being envied may drive contrastive knowledge behaviors of sharing and hiding, which subsequently impact employee innovation. The study further examines how the zero-sum game beliefs of the envied individual may moderate these mechanisms.Design/methodology/approachThis study builds on territorial and belongingness theories to delineate the contrastive motivations for knowledge hiding and knowledge sharing. This study tests a moderated mediation model through a multisource survey design involving 225 employees.FindingsThe results support the notion that perceptions of being envied are linked to both knowledge hiding and knowledge sharing; however, the indirect effect of being envied on innovation is observed only through knowledge sharing. The indirect positive link between perceptions of being envied and innovation via knowledge sharing is weakened when the envied employee holds high zero-sum game beliefs.Originality/valueThis study advances knowledge scholarship by identifying and testing the organizationally relevant but largely overlooked antecedent of being envied at work. The results provide useful insights to practitioners on how sharing or hiding knowledge serves as a strategic asset in response to being envied at work and how this may in turn impact employee innovation.

Uncovering the Contrasting Binding Behavior of Plant Flavonoids Fisetin and Morin Having Subsidiary Hydroxyl Groups (-OH) with HRAS1 and HRAS2 i-Motif DNA Structures: Decoding the Structural Alterations and Positional Influences.

Research on the interactions of naturally existing flavonoids with various noncanonical DNA such as i-motif (IM) DNA structures is helpful in comprehending the molecular basis of binding mode as well as providing future direction for the application and invention of novel effective therapeutic drugs. IM DNA structures have been identified as prospective anticancer therapeutic targets, and flavonoids are smaller molecules with a variety of health-promoting attributes, including anticancer activities. The extensive investigation comprising a series of techniques reveals the contrasting mode of the binding behavior of fisetin and morin with various IM DNA structures. We have discovered that structural alterations of hydroxyl groups located at different places of aromatic rings influence flavonoid's reactivity. This minor structural alteration appears to be critical for fisetin and morin's capacity to interact differentially with HRAS1 and HRAS2 IM DNA. Hence, fisetin appears to be an efficient ligand for HRAS1 and morin is considered to be an efficient ligand for HRAS2 IM DNA. This novel exploration opens up the possibility of employing the strategy for regulation of gene expression in cancerous cells. Our finding also reveals the flavonoid-mediated specific interaction with IM DNA while pointing toward tangible strategies for drug discovery and other essential cellular functions.

Investigation of the Dielectric Properties of Graphite and Carbon Black-Filled Composites as Electromagnetic Interference Shielding Coatings

The main purpose of electromagnetic interference (EMI) shielding coatings is the insulation of sensitive devices and protect people from electromagnetic field exposure due to its effects on the human body. This paper investigates the dielectric properties, and electromagnetic shielding performances of graphite and carbon black (CB) filled epoxy matrix composites produced by the mechanical mixing method. The sample compositions were created at rates ranging from 1 to 7 wt%. Samples were analyzed by Vector Network Analyzer (VNA) using the coaxial method in the range of 1–14 GHz, including L band, S band, C band, X band and partially Ku band. After determining the scattering parameters with VNA, AC conductivity, absorption, reflection and total shielding efficiency values were calculated. At high frequencies, almost all the samples showed higher AC conductivity. CB-filled samples show higher AC conductivity than graphite-filled samples. The total shielding efficiency (SET) of the graphite-added samples (19–21 dB) is slightly higher than the carbon black-added samples (8–17 dB). Distinct filling ratios in graphite-added samples result in closer shielding behavior in contrast to carbon black-added samples. However, higher shielding efficiency is observed as the CB filler ratio increases. The shielding efficiencies of the samples with both types of filling materials vary little depending on the frequency. Reflection is the main mechanism of the shielding efficiency, which constitutes the majority of total efficiency for all types of samples.

Effects of PET and RFCC on the dynamic modulus, phase angle, and complex viscosity of asphalt concrete

With economic and social development, the total amount of domestic and industrial solid waste discharged is considerable. In 2020, Vietnam generated about 2.2 million tons of plastic waste and 2 million tons of industrial solid waste. And most of them are landfilled and take a long time to decompose. This has dramatically affected the environment, costly land resources, and considerable transportation, burial, and management costs of those landfills. Therefore, many scientists have studied to recycle these wastes. There are two approaches to using recycled waste in hot mix asphalt (HMA). Waste plastic changes the properties of the asphalt binder, and solid waste replaces coarse particles in an asphalt mixture. During the research on using recycled waste for asphalt concrete, PET (Poly Ethylene Terephthalate) and RFCC (Residue Fluid Catalytic Cracking) were chosen for the study. This paper presents a study on the influence of PET (with 0.2% content in HMA) and RFCC (with 5% content in HMA) on the viscoelastic property of asphalt concrete based on dynamic modulus, phase angle, and complex viscosity values. At high temperatures, HMA using PET and RFCC exhibit complete elastic behavior (φ ≈ 50) in contrast to the viscous elastic behavior of the control sample (φ ≈ 150). Compared control sample, RFCC significantly increased the stiffness of HMA at low and high temperatures; with the dynamic modulus of HMA using RFCC increased 1.1 times at low and 1.6 times at high temperatures; the viscosity of HMA using RFCC and PET decreased 10 times and 7 times at low temperatures.

Active dynamics of linear chains and rings in porous media.

To understand the dynamical and conformational properties of deformable active agents in porous media, we computationally investigate the dynamics of linear chains and rings made of active Brownian monomers. In porous media, flexible linear chains and rings always migrate smoothly and undergo activity-induced swelling. However, semiflexible linear chains though navigate smoothly, shrink at lower activities, followed by swelling at higher activities, while semiflexible rings exhibit a contrasting behavior. Semiflexible rings shrink, get trapped at lower activities, and escape at higher activities. This demonstrates how activity and topology interplay and control the structure and dynamics of linear chains and rings in porous media. We envision that our study will shed light on understanding the mode of transport of shape-changing active agents in porous media.

Influence of microscope settings on dislocation imaging in transmission forescattered electron imaging (t-FSEI)

This work analyzes the influence of several microscope settings, namely, sample-forescattered electron detector (FSD) distance, and tilting conditions on the characteristics of the dislocation contrast imaged in transmission forescattered electron imaging (t-FSEI). The dislocation contrast behaviors of characteristic dislocation configurations of two Fe-based alloys, namely an α’-martensitic (body-centered cubic, bcc) Fe33Ni alloy (wt%), and an austenitic (face-centered cubic, fcc) Fe-30Mn-6.5Al-0.3C alloy (wt%) were investigated on thin foil samples by using different on-axis transmission Kikuchi diffraction (TKD) configurations, namely t-FSEI, bright-field (BF) t-FSEI and electron channeling contrast imaging (ECCI). The set-ups use transmission Kikuchi electron patterns to orient the crystal into controlled diffraction conditions. Imaging parameters such as dislocation contrast intensity and information depth are analyzed and compared to those obtained in the ECCI mode under the same microscope conditions. These effects are associated with the attenuation of Bragg scattering by high-angle scattering processes and the electron channeling mechanism, respectively. The experimental analysis sets the microscope settings for optimum dislocation imaging in t-FSEI.

Seismic signatures of partial steam saturation in fractured geothermal reservoirs: Insights from poroelasticity

Detecting the presence of gaseous formation fluids, estimating the respective volumes, and characterizing their spatial distribution are important for a wide range of applications, notably for geothermal energy production. The ability to obtain such information from remote geophysical measurements constitutes a fundamental challenge, which needs to be overcome to address a wide range of problems, such as the estimation of the reservoir temperature and pressure conditions. With these motivations, we compute the body wave velocities of a fractured granitic geothermal reservoir formation with varying quantities of steam to analyze the seismic signatures in a partial saturation context. We use a poroelastic upscaling approach that accounts for mesoscale fluid pressure diffusion (FPD) effects induced by the seismic strain field, and, thus, describes the governing physical processes more accurately than standard representations. Changes in seismic velocities due to steam saturation are compared with changes associated with fracture density variations, as both are plausible results of pressure changes in geothermal reservoirs. We find that steam saturation has a significant impact on P-wave velocities while affecting S-wave velocities to a significantly lesser extent. This contrasting behavior allows us to discriminate between fracture density and steam saturation changes by means of P- and S-wave velocity ratio analyses. To evaluate the potential of seismic methods to provide this information, a canonical geothermal reservoir model is used to compute the Rayleigh wave velocity dispersion and seismic reflection amplitude variation with angle (AVA) curves. These studies reveal that AVA analyses allow differentiating changes in fracture density from changes in steam saturation. We also note that the Rayleigh-wave-based techniques are much less sensitive to steam content changes than to fracture density changes. Comparisons with elastic approaches indicate that including FPD effects through the use of a poroelastic model is crucial for the reliable detection and characterization of steam in fractured geothermal reservoirs.

In Situ Tensile Testing under High-Speed Optical Recording to Determine Hierarchical Damage Kinetics in Polymer Layers of Flax Fibre Elements.

This study aims at better understanding the damage and fracture kinetics in flax fibre elements at both the unitary and bundle scales, using an experimental setup allowing optical observation at high recording rate in the course of tensile loading. Defects and issues from flax unitary fibre extraction are quantitated using polarized light microscopy. Tensile loading is conducted according to a particular setup, adapted to fibres of 10 to 20 µm in diameter and 10 mm in length. Optical recording using a high-speed camera is performed during loading up to the failure at acquisition, with speed ranging from 108,000 to 270,000 frames per second. Crack initiation in polymer layers of fibre elements, propagation as well as damage mechanisms are captured. The results show different failure scenarios depending on the fibre element's nature. In particular, fractured fibres underline either a fully transverse failure propagation or a combination of transverse and longitudinal cracking with different balances. Image recordings with high time resolution of down to 3.7 μs suggest an unstable system and transverse crack speed higher than 4 m/s and a slower propagation for longitudinal crack deviation. Failure propagation monitoring and fracture mechanism studies in individual natural fibre or bundles, using tensile load with optical observation, showed contrasted behaviour and the importance of the structural scale exanimated. This study can help in tailoring the eco-design of flax-based composites, in terms of toughness and mechanical performances, for both replacement of synthetic fibre materials and innovative composites with advanced properties.

Calcium isotope fractionation associated with adsorption and desorption on/from δ-MnO2

Small mineral particles present in soils, such as clay minerals and some oxyhydroxides, constitute important nutrient reservoirs. This behavior is due to the negative charges and high specific surface areas of these particles allowing them to adsorb cations such as calcium (Ca), a macronutrient that occupies key physiological and structural functions in plant metabolism. Although the chemical reactivity of clay minerals is rather well-known in the literature, especially toward macronutrients such as Ca, that of oxyhydroxides such as phyllomanganate minerals remains largely unexplored.To enhance our understanding of the mechanisms at the origin of the storage/release of the different isotopes of Ca in a soil solution, the possible fractionation between 40Ca and 44Ca during adsorption and desorption of Ca on a synthetic phyllomanganate, abiotically precipitated in the laboratory [synthetic analog of vernadite (δ-MnO2)], was studied. Experiments were performed in batch (closed system), and several parameters (time, pH of the solution, Ca concentration and nature and concentration of the desorbent) were tested to cover a large range of physicochemical conditions.This study demonstrated that the light 40Ca isotope is preferentially adsorbed on δ-MnO2, with Δ44/40Ca (the apparent fractionation of the aqueous solution at the stationnary state of adsorption compared to the initial one) of the adsorbed Ca that can reach 1.19 ± 0.15‰. The results showed that this isotopic fractionation occurs at chemical equilibrium in a closed system and that the isotopic fractionation measured in this study during Ca adsorption on phyllomanganate is significantly higher than that reported in the literature during Ca adsorption on other soil constituents such as clay minerals. At pH below 4 Ca occupies only the interlayer/basal sites whereas above this pH Ca fills interlayer/basal sites (∼86%) and edges sites (∼14%). By combining the experimental data obtained at different pH values, initial Ca concentrations and interaction times, our results suggest that isotopic signature of the Ca adsorbed on δ-MnO2 is dependent on the nature of the site involved in the adsorption step (i.e., enriched in 40Ca in the interlayer with Δ44/40Ca equal to −0.43‰ and enriched in 44Ca when bound to the edges with Δ44/40Ca equal to +3.5‰). As revealed by surface complexation modeling, such contrasting behavior between the two types of adsorption sites could be due to the bidendate nature of the Ca adsorption occurring on edges and to ion exchange of Ca2+ with H+ in the interlayer sites. Finally, desorption experiments point to total but not instantaneous Ca desorption, probably due to a partial collapse of the interlayer with some ions used to desorb Ca2+ (K+, NH4+, hexaamine-cobalt). This suggests that the amount of bioavailable Ca in soils by simple ion-exchange reactions is highly dependent on the nature of the ions which could desorb Ca present in the soil solution.

Species-specific influence of hydroclimate on secondary growth of three coexisting conifers in a temperate Andean forest in south-central Chile

There is limited knowledge on the growth responses of coexisting conifer species to water conditions in the Andean region of South America- particularly in South-Central Chile (37°−40°S) where high temperatures and drought risk is expected to increase in the future. Here, we used wood cores from living trees and cross-sections of stumps to study the secondary growth responses to hydroclimatic environmental variables in Araucaria araucana, Austrocedrus chilensis and Prumnopitys andina, three coexisting conifers in a temperate Andean forest. The standardized tree-ring chronologies are robust and have been well replicated over the past two centuries, with an expressed population signal greater than 0.90. Our findings indicate that chronologies of Austrocedrus and Prumnopitys were quite similar, while Araucaria was almost independent. The secondary growth of Araucaria was negatively related to August precipitation and river runoff, likely due to a high probability of snow cover at high elevations in winter. In contrast, the secondary growth of Austrocedrus and Prumnopitys was positively associated with precipitation and streamflow and negatively with high maximum temperatures in two seasons, summer (December to February) and autumn (April to May). Prumnopitys growth was strongly associated with streamflow during last year´s and current year´s growing seasons. In the years 1962, 1998 and 2008 there occurred severe droughts, which were associated with growth reductions in the three conifers. Araucaria growth showed the greatest resistance to drought, while Austrocedrus was the most resilient to drought and showed the greatest ability for growth recovery after a drought. Araucaria growth showed near-constant resistance, recovery and resilience to drought during the study period, while Austrocedrus growth showed high recovery and resilience after the 1962 and 2008 droughts. Our results revealed contrasting behavior of coexisting conifers with respect to hydroclimate, which could help predict future changes in the performance of temperate Andean forests in a potentially drier and warmer climate.

Mechanisms of fast crystallization in amorphous Ge2Sb2Te5 films

Ge2Sb2Te5 has been widely utilized as phase-change films, while a long-standing problem is the seemingly paradoxical feature; RT durability of amorphous states which undergo rapid crystallization upon pulsed, optical/electrical excitations. The model that takes high fragility of the film into account has been proposed for reconciling this contrastive behavior, while the idea faces some difficulties. This work suggests through simple calculations that explosive latent-heat spikes produced by ns pulses could accelerate the crystallization. Although crystal growths are assumed to need some durations, the latent heat generated by shorter stimuli is able to trigger the swift crystallization.

Physical-biological drivers modulating phytoplankton seasonal succession along the Northern Antarctic Peninsula

The Northern Antarctic Peninsula (NAP) shows shifts in phytoplankton distribution and composition along its warming marine ecosystems. However, despite recent efforts to mechanistically understand these changes, little focus has been given to the phytoplankton seasonal succession, remaining uncertainties regarding to distribution patterns of emerging taxa along the NAP. To fill this gap, we collected phytoplankton (pigment and microscopy analysis) and physico-chemical datasets during spring and summer (November, February and March) of 2013/2014 and 2014/2015 off the NAP. Satellite measurements (sea surface temperature, sea ice concentration and chlorophyll-a) were used to extend the temporal coverage of analysis associated with the in situ sampling. We improved the quantification and distribution pattern of emerging taxa, such as dinoflagellates and cryptophytes, and described a contrasting seasonal behavior and distinct fundamental niche between centric and pennate diatoms. Cryptophytes and pennate diatoms preferentially occupied relatively shallower mixing layers compared with centric diatoms and dinoflagellates, suggesting differences between these groups in distribution and environment occupation over the phytoplankton seasonal succession. Under colder conditions, negative sea surface temperature anomalies were associated with positive anomalies of sea ice concentration and duration. Therefore, based on sea ice–phytoplankton growth relationship, large phytoplankton biomass accumulation was expected during the spring/summer of 2013/2014 and 2014/2015 along the NAP. However, there was a decoupling between sea ice concentration/duration and phytoplankton biomass, characterizing two seasonal periods of low biomass accumulation (negative chlorophyll-a anomalies), associated with the top-down control in the region. These results provide an improved mechanistic understanding on physical-biological drivers modulating phytoplankton seasonal succession along the Antarctic coastal waters.

Factors influencing students' attitudes toward bullying: A multilevel analysis from Mainland China, Hong Kong, and Taipei

AbstractThe present study investigated how students' attitudes toward bullying were influenced simultaneously by personal and contextual factors in Mainland China, Hong Kong, and Taipei. Participants included 25,338 students (15‐year‐olds, from grade 7 to 12) and 663 schools from Mainland China, Hong Kong, and Taipei drawn from the Program for International Student Assessment 2018. Multilevel structural equation modeling with Bayesian estimation was conducted for data analysis. The results showed that, for personal factors, girls had stronger anti‐bullying attitudes than boys in each sample. Resilience and self‐efficacy predicted students' anti‐bullying attitudes positively and significantly in all three regions. For family contextual factors, parents' emotional support had positive effects on students' attitudes toward bullying in three regions. For school contextual factors, there was no consistent result among the three regions. School location and school belonging were positive predictors of students' anti‐bullying attitudes in Mainland China. By contrast, class size and student behavior hindering learning negatively correlated with students' anti‐bullying attitudes in Hong Kong. In Taipei, students in public schools were more likely to form anti‐bullying attitudes, and a positive association was found between the student–teacher ratio and students' attitudes toward bullying. Distinguishing the commonalities and differences in the factors influencing students' attitudes toward bullying in Mainland China, Hong Kong, and Taipei provides empirical evidence to understand school bullying prevention and control mechanism.

Early Educators’ Perceptions of Behavior

We explored how teachers perceived challenging behavior in contrast to behaviors that exemplify social-emotional competence, and how descriptions of behavior varied based on child demographics such as gender, race/ethnicity, and disability status. Using a DisCrit lens, we conducted this study under the assumption that perceptions of behavior may be informed by teachers’ implicit biases. Fourteen preschool teachers shared their perspectives on behaviors they saw in the classroom, as exemplified by descriptions of the two children they considered the most socially-emotionally successful, A/Z, and the two they considered the most challenging, C/E. Children in the A/Z group were 54% female, 46% male, 54% White, 29% Black, and 82% did not receive special education services or need screening. Children in the C/E group were 86% male, 14% female, 46% Black, 36% White, and 75% were either receiving special education services or identified by teachers as needing a referral for screening. Positive A/Z behaviors included being a model, leader, or helper; having good play skills, manners, and verbal skills; and loving to learn. The challenging behaviors for C/E students included being hard to connect with; engaging in physical aggression and defiance; and having communication difficulties and poor self-regulation skills. These findings help us understand the role of implicit bias, systems issues, and the importance of culturally responsive practices in early childhood settings.

Finding an effective MRI sequence to visualise the electroporated area in plant-based models by quantitative mapping

Plant-based models can reduce the number of animal studies for electroporation research in medical cancer treatment modalities like irreversible electroporation. Magnetic resonance imaging (MRI) provides volumetric visualisation of electroporated animal or plant tissues; however, contrast behaviour is complex, depending on tissue and sequence parameters. This study numerically analysed contrast between electroporated and non-electroporated tissue at 1.5 T in various MRI sequences (DWI, T1W, T2W, T2*W, PDW, FLAIR) performed 4 h after electroporation in apples (N = 4) and potatoes (N = 8). Sequence parameters (inversion time [TI], echo time [TE], b-value) for optimal contrast and electroporation-mediated changes in T1 and T2 relaxation times and apparent diffusion coefficient (ADC) were determined for potato (N = 4) using quantitative parameter mapping. FLAIR showed the electroporated zone in potatoes with best contrast, whereas no sequence yielded clear visibility in apples. After electroporation, T1 and T2 in potato decreased by 29% ([1245 ± 54 to 886 ± 119] ms) and 12% ([249 ± 17 to 217 ± 12] ms), respectively. ADC increased by 11% ([1303 ± 25 to 1449 ± 28] × 10–6 mm2/s). Optimal contrast was found for TI = 1000 ms, low TE and high b-value. T1 was most sensitive to EP-mediated tissue changes. Future research could use this methodology and findings to obtain high-contrast MR images of electroporated and non-electroporated biological tissues.