Systematic Trends Research Articles

Impact of nuclear rotation corrections on alpha decay half-lives of superheavy nuclei within 98 ≤ Z ≤ 120

The influence of nuclear rotation on the decay half-lives of superheavy nuclei within the range 98≤Z≤120 is investigated using the axially deformed relativistic Hartree-Bogoliubov theory in the continuum (DRHBc) with the PC-PK1 parameter set. The deduced DRHBc decay energies (with and without the rotation effect) are compared with those calculated from the macroscopic-microscopic WS4 and the available experimental binding energies. Six semi-empirical formulae, such as the Viola-Seaborg formula (VSS), the modified Brown formula (mB1), the semi-empirical relationship based on fission theory (SemFIS2), the Royer formula (R), the Wang formula (Wang) and the modified YQZR formula (MYQZR) are employed to estimate the half-lives of α decay. Among these formulae, the half-live predictions of SemFIS2 are found to gradually deviate from the systematic trend beyond Nd=184, showing that the probability of undergoing spontaneous fission is less feasible beyond this point. A minimum is observed at Nd=184, reflecting its neutron shell closure for the mass region considered on the nuclear chart. The results further indicate that, for 98≤Z≤104, the predictions of all semi-empirical formulae are more closely matched to the available experimental data when the rotation effect is taken into account. However, we have demonstrated that the effect of nuclear rotation gradually reduces as the atomic nucleus becomes heavier.

The unusual stubble burning season of 2020 in northern India: a satellite perspective

ABSTRACT We analysed nine years (2012–2019) of fire observations from the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi-NPP satellite to assess the post-monsoon crop stubble burning activities over northern India. The 2020 fire season (September-November) was analysed extensively, and spatiotemporal trends were examined. Our analysis indicates that about 60% of post-monsoon fires occurred in the state of Punjab, followed by Madhya Pradesh (11%), Haryana (4%), and Uttar Pradesh (3%). The year 2020 saw the greatest fire activity in Punjab and across the country since 2016. Over the nine years, Punjab did not show any systematic trends in fire activities, whereas Haryana and Madhya Pradesh demonstrated an overall decreasing (45% lower in 2020 compared to the 2012–2019 mean) and increasing (185% more in 2020 compared to 2012–2019 mean) trends, respectively. The high fire occurance in the Punjab are related to high percentage of crop area with specific variety of rice, which produces high straw load and mature in shorter time. The increase in Madhya Pradesh is directly related to an increase in rice crop planting area over the years, whereas the decrease in Haryana is related to changes in crop residue management. The uncertainty analysis in this paper shows that over a given region, day-to-day variability in fire counts can have sampling biases due to changing satellite viewing geometry. Furthermore, long-term trends can also be impacted by the reduced sampling of satellite fire detections under cloudy conditions. However, large scale spatiotemporal analysis of fires in this area provides crucial and well sought-after information for crop fire control and air quality management in north India. The district level analysis for the four states signifies the critical information that satellites can provide for identifying hotspots and planning regionally focused mitigation strategies to curb pollution from crop burning fires.

Control of Source‐To‐Sink Processes on the Dispersal, Fractionation, and Deposition of Magnetic Minerals in a Tropical Mesotidal Estuarine System

AbstractThis study aims to elucidate the control of source‐to‐sink processes on the sediment dynamics of a complex mesotidal tropical estuarine system using rock magnetic, sedimentological, mineralogical, and geochemical methods. Integration of multiproxy data of catchment rocks, riverbank and hinterland soils, and bedload sediments from various depositional environment of Mandovi estuary revealed a marked change in the magnetic mineral composition and accumulation pattern. The magnetic mineralogy mainly comprised ferri‐ (magnetite, titanomagnetite) and antiferromagnetic (hematite, goethite) minerals. Higher accumulation of coarser magnetic particles in the catchment area followed by a systematic trend of progressive fining of magnetic grain size in the down reaches of the estuary can be attributed to the decrease in transport energy. Enhanced accumulation of coarser magnetic particles in the estuarine region can be reconciled with the strong tidal and wave‐induced bottom currents, which preferentially favored mineral‐density selective fractionation resulting in higher deposition of heavy (magnetic) particles. A clear trend of loss of fluvial‐derived fine silt‐size clastic sediments and selective retention of coarser and heavy magnetic particles within the estuary can be attributed to the hydrodynamic driven sediment partitioning regime, which inhibited the permanent settling of fine sediment fraction and are therefore frequently flushed out to the sea. A marked drop in S‐ratio in different zones of the estuary can be linked to the increased input of high coercive magnetic particles derived from pedogenic soils along eroding riverbanks. We further demonstrate that the S‐ratio is an effective parameter to track the riverbank erosion in an estuarine system.

Polarized radiative transfer: Monte Carlo code Ventspils RTMC. Testing of it and RADMC3D

We have created Monte Carlo code Ventspils RTMC for polarized radiative transfer modelling in an isotropic, optically inactive medium of arbitrary configuration and morphology, and made it public. Its main advantages are simplicity of structure and usage, which can be a benefit for simple physical problems, together with use of sound and fully defined basic equations describing the scattering process. We compared the numeric results of Ventspils RTMC with those of RADMC3D created by Dullemond et al., as well as with the direct solution of Fredholm integral equations for source functions. A model of homogeneous sphere with Rayleigh scattering and concentric star inside it was used for comparison. The conclusion is that all three codes give essentially the same results if the radial optical thickness of the sphere does not exceed 5. If the optical thickness is between 5 and 10 then the statistical noise increases, and some small but systematic trends of differences appear between the results of three codes; however, the three codes are compatible. For optical thickness exceeding 10, the current version of Ventspils RTMC is too slow. There is a theoretical uncertainty about the adequacy of diffusion approximation of polarized radiative transfer used in RADMC3D for optical thickness exceeding 15. While RADMC3D is a very complex code usable for broad scope of applications, our Ventspils RTMC is a much simpler code usable for continuum transfer in case of modest optical thickness.

Sapling recruitment does not compensate for increased tree mortality under climate change

Sapling recruitment within established stands plays an important role in the long-term functionality of forest ecosystems. However, the specific impacts of climate change on sapling recruitment and its underlying mechanisms remain unclear. We hypothesized that sapling recruitment is directly affected by climate change and indirectly through the responses of tree mortality and growth to climate change as well as their induced modification of neighbourhood conditions. We employed a dataset of 173 permanent sample plots with individual stems that were spatially mapped and monitored at 5-year intervals from 1986 to 2010 in the central boreal forests of North America. By constructing structural equation models (SEMs), we examined how sapling recruitment probability may, directly and indirectly, respond to climate change through the mortality and growth of established trees, neighbourhood crowding, and functional and phylogenetic dissimilarities. We used the middle calendar year of a 5-year census period to represent recent systematic temporal trends in climate change. Our SEMs revealed that sapling recruitment probability did not respond significantly directly to temporal climate change in the studied forests, where atmospheric CO2 concentration, air temperature, and climatic water availability simultaneously increased temporally. However, the temporally increased mortality and growth of neighbourhood established trees (all stems except for new recruits) exerted indirect negative effects on sapling recruitment probability. Furthermore, temporally increased neighbourhood crowding had an indirect adverse effect, while temporally increased neighbourhood shade tolerance and phylogenetic dissimilarities had weak indirect positive effects on sapling recruitment probability. Collectively, temporal climate change had a significant total negative effect on sapling recruitment probability. Our analysis demonstrated multiple mechanisms that simultaneously regulated the effect of temporal climate change on sapling recruitment. Our results emphasized that sapling recruitment does not compensate for increased tree mortality. We suggest that even so-called favourable climate change could threaten the long-term functionality of boreal forest ecosystems.

Atomic scale structure and bond stretching force constants in stoichiometric and off-stoichiometric kesterites.

The deviation from stoichiometry and the understanding of its consequences are key factors for the application of kesterites as solar cell absorbers. Therefore, this study investigates the local atomic structure of off-stoichiometric Cu2ZnSnS4 (CZTS), Cu2ZnSnSe4 (CZTSe) and Cu2ZnGeSe4 (CZGSe) by means of Extended X-ray Absorption Fine Structure Spectroscopy. Temperature dependent measurements yield the bond stretching force constants of all cation-anion bonds in stoichiometric CZTS and CZTSe and nearly stoichiometric CZGSe. Low temperature measurements allow high precision analysis of the influence of off-stoichiometry on the element specific average bond lengths and their variances. The overall comparison between the materials is in excellent agreement with measures like ionic/atomic radii and bond ionicities. Furthermore, the small uncertainties allow the identification of systematic trends in the Cu-Se and Zn-Se bond lengths of CZTSe and CZGSe. These trends are discussed in context of the types and concentrations of certain point defects, which gives insight into the possible local configurations and their influence on the average structural parameters. The findings complement the understanding of the effect of off-stoichiometry on the local structure of kesterites, which affects their electronic properties and thus their application for solar cells.

An Update of the Catalog of Radial Velocity Standard Stars from the APOGEE DR17

We present an updated catalog of 46,753 radial velocity (RV) standard stars selected from the APOGEE DR17. These stars cover the Northern and Southern Hemispheres almost evenly, with 62% being red giants and 38% being main sequence stars. These RV standard stars are stable on a baseline longer than 200 days (with 54% longer than one year and 10% longer than five years) with a median stability better than 215 m s−1. The average number of observations of those stars is 5 and each observation is required to have signal-to-noise ratio greater than 50 and RV measurement error smaller than 500 m s−1. Based on the new APOGEE RV standard star catalog, we have checked the RV zero-points (RVZPs) for current large-scale stellar spectroscopic surveys including RAVE, LAMOST, GALAH and Gaia. By careful analysis, we estimate their mean RVZP to be +0.149 km s−1, +4.574 km s−1 (for LRS), −0.031 km s−1 and +0.014 km s−1, respectively, for the four surveys. In the RAVE, LAMOST (for MRS), GALAH and Gaia surveys, RVZP exhibits a systematic trend with stellar parameters (mainly [Fe/H], T eff, log g, G BP − G RP and G RVS). The corrections to those small but clear RVZPs are of vital importance for these massive spectroscopic surveys in various studies that require extremely high RV accuracies.

Species distribution modelling in the Southwestern Atlantic Ocean: A systematic review and trends

Species distribution modelling (SDM) of marine organisms is widely developed for biogeography, ecology and management purposes. However, most studies continue to focus on the Global North, with fewer examples for the Global South. We carried out a bibliometric analysis to characterise aspects of studies conducting SDM for species in the Southwestern Atlantic Ocean (SWAO), focusing on the type of input data, taxonomic groups studied, focus of research, methods applied, and international collaboration between countries. Studies on megafauna and fisheries resources, based on presence-only and scenopoetic input data, applying Maximum Entropy (MaxEnt) and generalized linear/additive models (GLM/GAM) predominate. Models applied to biogeography/current species distribution were the most common, followed by biological invasion. Brazil figures as the most prolific country publishing in SWAO, and has more collaborations with the United States of America, Europe, and South Africa than with its neighbours Uruguay and Argentina, who formed a separate cluster. Research groups based on coauthorship of the 30 most frequent authors seem to be mostly isolated, with only two research groups collaborating to each other. In addition, we fit a Binomial generalised linear model (BGLM) to explore how many predictors (layers) would be sufficient to reach an excellent modelling performance based on Area Under the Curve (AUC) values. The BGLM indicated at least 5–8 layers would be necessary to have a 50 % chance of achieving excellent model performance (AUC ≥ 0.9), but we urge caution regarding this result and briefly discuss it. The literature review was used as a baseline to discuss aspects of our findings and highlight the need to increase SDM application in the SWAO and to strengthen international collaboration between Latin American countries. Finally, we provide recommendations on how researchers could approach some of the gaps we found.

Optimized temporal binning of comparison star measurements for differential photometry

ABSTRACT Ground-based, high precision observations of the light curves of objects such as transiting exoplanets rely on the application of differential photometry. The flux of the target object is measured relative to a comparison star in the same field, allowing correction for systematic trends in the light curve, mainly due to atmospheric effects including the variation of extinction with airmass. However, the precision of the light curve is then limited by the random noise for the measurements of both the target object and the comparison star. For time-resolved photometry using short exposure times of up to a few tens of seconds, the time-scale of the systematic variations due to atmospheric (or other) effects can be much longer than the cadence of the observations. In this case, the overall signal-to-noise ratio of the observation may be improved significantly by applying some temporal binning to the measurements of the comparison star, before comparison with the target object, without reducing the cadence of the overall light curve. In this paper, we will describe a data reduction pipeline for implementing this method which optimizes the number of frames to be binned for the comparison star, and we present example results for time-resolved photometric data. An example of applying the technique on an exoplanet transit light curve of WASP-166b is presented using four comparison stars of different magnitudes.

A bibliometric and content analysis of membrane electrode assemblies for proton exchange membrane fuel cells

Membrane electrode assemblies (MEA) are the core components of proton exchange membrane fuel cells (PEMFCs), which provide the microchannels for multiphase mass transfer and sites for electrochemical reaction. In this study, 2379 literatures related to membrane electrode assembly for PEMFCs were obtained from the Web of Science literature database (up to February 25, 2023). The number of papers published, citation frequency, publication time and clusters were analyzed using the VOSviewer data analysis platform, and the development history and hotspot changes in the field were discussed. The results show that since 2003, the number of papers published in the MEA field has shown a trend of first increasing, then decreasing, and last increasing. The three countries that have published the most papers in the MEA field are China, the United States and South Korea, of which the high-quality papers of the USA are cited the most. According to the keyword co-occurrence mapping, this field has three clusters containing 72 key words. The development of the MEA field consists of three stages, including the initial stage, development stage, and optimization stage. The analysis results were visualized, aiming to provide a systematic review and trend outlook of the research in the field related to MEA of PEMFCs, to discuss the current research trends and hotspots, and to explore the contents that need to be improved in the subsequent research.

Spectroscopic Characterization of Thiacarbocyanine Dye Molecules Adsorbed on Hexagonal Boron Nitride: a Time-Resolved Study.

Physisorption on hexagonal boron nitride (hBN) gained interest over the years thanks to its properties (chemically and thermally stable, insulating properties, etc.) and similarities to the well-known graphene. A recent study showed flat-on adsorption of several cationic thiacarbocyanine dyes on hBN with a tendency to form weakly coupled H- or I-type aggregates, while a zwitterionic thiacarbocyanine dye rather led to a tilted adsorption. With this in-depth time-resolved study using the TC-SPC technique, we confirm the results proven by adsorption isotherms, atomic force microscopy, and stationary state spectroscopy combined with molecular mechanics simulations and estimation of the corresponding exciton interaction. The absence of a systematic trend for the dependence of the decay times, normalized amplitudes of the decay components, and contribution of different components to the stationary emission spectra upon the emission wavelength observed for all studied dyes and coverages suggests the occurrence of a single emitting species. At low coverage levels, the non-mono-exponential character of the decays was attributed to adsorption on different sites characterized by different intramolecular rotational freedom or energy transfer to nonfluorescent traps or a combination of both. The difference between the decay rates of the four dyes reflects a different density of the nonfluorescent traps. Although the decay time of the unquenched dyes was in the order of magnitude of that of dye monomers in a rigid environment, it is also compatible with weakly coupled aggregates such as proposed earlier based on the stationary spectra. Hence, the adsorption leads to a rigid environment of the dyes, blocking internal conversion. Increasing the concentration of the dye solution from which the adsorption on hBN occurs increases not only the coverage of the hBN surface but also the extent of energy transfer to nonfluorescent traps. For TDC (5,5-dichloro-3-3'-diethyl-9-ethyl-thiacarbocyanine) and TD2 (3-3'-diethyl-9-ethyl-thiacarbocyanine), besides direct energy transfer to traps, exciton hopping between dye dimers followed by energy transfer to these traps occurs, which resulted in a decreasing decay time of the longest decaying component. For all dyes, it was also possible to analyze the fluorescence decays as a stretched exponential as would be expected for energy transfer to randomly distributed traps in a two-dimensional (2D) geometry. This analysis yielded a fluorescence decay time of the unquenched dyes similar to the longest decay time obtained by analysis of the fluorescence decays as a sum of three of four exponentials.

Natural fracture patterns at Swift Reservoir anticline, NW Montana: the influence of structural position and lithology from multiple observation scales

Abstract. Subsurface datasets typically lack the resolution or coverage to adequately sample fracture networks in 3D, and fracture properties are typically extrapolated from available data (e.g. seismic data or wellbore image logs). Here we assess the applicability of extrapolating fracture properties (orientation, length, and intensity) across observation scales in deformed, mechanically layered carbonate rocks. Data derived from high-resolution field images, medium-resolution digital outcrop data, and relatively low-resolution satellite imagery at Swift Reservoir anticline, NW Montana are leveraged to (i) assess interacting structural and stratigraphic controls on fracture development, and (ii) compare estimated fracture properties derived from multiple observation scales. We show that hinge-parallel and hinge-perpendicular fractures (i) make up the majority of fractures at the site; (ii) are consistently oriented with respect to the fold hinge, despite along-strike variability in the fold hinge orientation; and (iii) exhibit systematic increases in intensity towards the anticline hinge. These fractures are interpreted as having formed during folding. Other fractures recorded at the site exhibit inconsistent orientations, show no systematic trends in fracture intensity, and are interpreted as being unrelated to fold formation. Fracture orientation data exhibit the greatest agreement across observation scales at hinge and forelimb positions, where hinge-parallel and hinge-perpendicular fracture sets are well developed, and little agreement on the anticline backlimb, where fracture orientations are less predictable and more dispersed. This indicates that the scaling of fracture properties at Swift Reservoir anticline is spatially variable and partly dependent on structural position. Our results suggest that accurate prediction and extrapolation of natural fracture properties in contractional settings requires the assessment of structural position, lithologic variability, and spatially variable fracture scaling relationships, as well as consideration of the deformation history before and after folding.

Development of two-layer zone model BRI2-CRIEPI applicable to fire PRA for nuclear power plants

In implementing practical fire Probabilistic Risk Assessment (PRA) for nuclear power plants, a practical fire model is required for more realistic fire scenarios. The fire simulation zone model BRI2-CRIEPI has been continuously improved to allow analysis considering the characteristics of compartment fires under mechanical ventilation conditions.In this study, the specific characteristics of the fire model under mechanical ventilation conditions to estimate inner pressure and flow rate fluctuation were newly applied, such as the relationship between compartment pressure and flow rate of a ventilating fan, i.e., the fan curve, the vitiation effect of the mass loss rate (MLR) due to the depletion of oxygen owing to fire progress, the representative oxygen concentration corresponding to the elevation of a fire source, and a thermal radiation feedback model from the flame and surrounding environment in case of flame impingement beneath the ceiling.The analytical results with the BRI2-CRIEPI were validated by full-scale compartment fire test results performed by the international Organisation for Economic Co-operation and Development (OECD) Nuclear Energy Agency (NEA) project PRISME3 (Propagation d'un incendie pour des scénarios multi-locaux élémentaires in French). Especially, validation result for HGL temperature, which is very important metric in the fire PRA, shows that there is no obvious bias (the model bias factor of 1.03) and no particular systematic trend (the model relative standard deviation of 0.14) in the model prediction.

Systematic Across‐Arc Variations of Molybdenum Isotopes in a Fluid‐Dominated Subduction Zone System

AbstractMass‐dependent Mo isotope variations are a promising new tracer to study magmatic processes in different geological settings. We report the first Mo isotope data for the Kamchatka arc system in the Northwest Pacific, comprising basaltic lavas of a complete Southeast‐Northwest traverse from the volcanic arc front through to the back arc region. The majority of volcanic centers investigated directly override the Hawaii‐Emperor Seamount Chain, which is currently being subducted underneath the arc system. Our Mo isotope data show systematic trends with Ce/Pb, Ce/Mo, Nb/Zr, La/Sm, and 143Nd/144Nd ratios from the volcanic arc front to the back arc. Arc front lavas have higher δ98/95Mo and lower Ce/Pb, Ce/Mo, Nb/Zr, La/Sm compared to back arc lavas. Because the involvement of subducted sediments can be excluded, we attribute the observed variations to a change in the mantle source composition from the arc front to the back arc regions. The isotopic and chemical budget of arc front lavas is dominated by a slab fluid component (high δ98/95Mo, low Ce/Pb, Ce/Mo), whereas mantle‐like Ce/Pb, Ce/Mo, elevated Nb/Zr and La/Sm in the back arc samples suggest an enriched mantle source. Combined δ98/95Mo, Nd, and Pb isotope data in back arc lavas are very similar to those observed for modern ocean island basalts from Hawaii. We thus explore the possibility that the back arc mantle was contaminated by a Hawaii‐type, enriched asthenospheric mantle component from the subducted Hawaii‐Emperor Seamount Chain.

(Invited) Diameter-Dependent Stacking of Squaraine Dye Molecules inside Chirality-Sorted Single-Wall Carbon Nanotubes

Filling of single-wall carbon nanotubes (SWCNTs) with organic dye molecules is a promising strategy to add new functionalities, for instance by aligning dipolar dyes in a one-dimensional (1D) head-to-tail coupled chain to obtain a giant enhancement of their nonlinear optical response,[1] or by photo-sensitizing the tubes in new wavelength ranges by excitation energy transfer (EET) from the dye to the SWCNTs, useful for photo-conversion applications.[2] The 1D stacking of molecules inside SWCNTs modulates both the properties of the molecules and of the SWCNTs. We found that the EET of squaraine-dye-filled SWCNTs reveals a pronounced SWCNT-diameter-dependence of the dye absorption, indicating a diameter-dependent stacking. By performing IR fluorescence excitation spectroscopy on a range of chirality-enriched samples of dye-filled SWCNTs with different chirality distributions, each shifted dye absorption wavelength observed through the EET can be unambiguously assigned to a specific encapsulating SWCNT chirality.[3] This reveals a systematic trend with diameter that can be associated with the J-aggregate- and H-aggregate-like interactions expected in close-packed single- and double-file stackings, as corroborated by a simple geometric model, and enables tuning of the optical properties of the 1D molecular arrays through the selection of proper SWCNT diameters.[1] S. Cambré, J. Campo, C. Beirnaert, C. Verlackt, P. Cool, W. Wenseleers, Nature Nanotechnol. 10(3) 248-252 (2015). [2] S. van Bezouw, D.H. Arias, R. Ihly, S. Cambré, A.J. Ferguson, J. Campo, J.C. Johnson, J. Defillet, W. Wenseleers, J.L. Blackburn, ACS Nano 12(7) 6881-6894 (2018). [3] S. Forel, H. Li, S. van Bezouw, J. Campo, L. Wieland, W. Wenseleers, B.S. Flavel, S. Cambré, Nanoscale 14, 8385-8397 (2022).

Resonance Raman spectra of blue copper proteins: Variable temperature spectra of Thermus thermophilus HB27 laccase

The resonance Raman (rR) spectra of the oxidized type 1 copper active site (CuT1) in Thermus thermophilus HB27 laccase (Tth-lac) has been determined in the 20 to 80 °C temperature range using 633-nm excitation. The positions and relative intensities of rR peaks are virtually independent of temperature, indicating that CuT1 ligation is robust over the investigated range. The intensity-weighted average of Tth-lac Cu-SCys vibrations (<ν(Cu-SCys)>) = 423 cm−1) is higher than those of most cupredoxins but is comparable to those of other multicopper oxidases (MCOs). <ν(Cu-SCys)> values for Tth-lac and several CuT1 centers in cupredoxins and MCOs do not correlate well with Cu-SCys bond lengths but do exhibit systematic trends with redox thermodynamic properties. PrologueF. Ann Walker was a great scholar and dear friend. While at Columbia in the early 1960s, I (HBG) followed her graduate work at Brown on the effects of axial ligands on vanadyl ion EPR spectra. Dick Carlin, her thesis adviser, invited me to serve as external member of her thesis committee. I joined, made my way to Providence, met her just before the exam, and greatly admired (enjoyed!) her thoughtful responses to questions from physical chemists about metal-oxo electronic structures. Our friendship grew stronger over the years, enhanced by lively discussions of heme protein chemistry in San Francisco, Pasadena, Tucson, and at Gordon Research Conferences. Ann was a superstar in biological inorganic chemistry. She will be sorely missed but not forgotten.

The COVID-19 pandemic eroded system support but not social solidarity.

While the World was busy mitigating the disastrous health and economic effects of the novel coronavirus, a less direct, but not less concerning peril has largely remained unexplored: the COVID-19 crisis may have disrupted some of the most fundamental social and political relationships in democratic societies. We interviewed samples resembling the national population of Denmark, Hungary, Italy and the US three times: in April, June and December of 2020 (14K observations). We show that multiple (but not all) measures of support for the political system decreased between April and December. Exploiting the panel setup, we demonstrate that within-respondent increases in indicators of pandemic fatigue (specifically, the perceived subjective burden of the pandemic and feelings of anomie) correspond to decreases in system support and increases in extreme anti-systemic attitudes. At the same time, we find no systematic trends in feelings of social solidarity, which are largely unaffected by changes in pandemic burden.

Seismic performance of sheet-pile wall supporting liquefiable backfill: Blind predictions of centrifuge model tests using Ta-Ger constitutive model

Blind numerical simulations of seven centrifuge tests with “identical” models of a sheet-pile wall supporting medium dense liquefiable backfill and subjected to seismic excitation were performed as part of the LEAP 2020 project. The analyses were conducted with FLAC using the Ta-Ger soil constitutive model. The Ta-Ger model parameters were calibrated against available laboratory DSS data on Ottawa sand with similar relative density with a focus on capturing at an element level: i) the liquefaction triggering resistance, ii) the post-liquefaction rate of shear-strain accumulation, iii) overburden effects on liquefaction triggering resistance and iv) realistic shear stress-strain responses. A single numerical model was built in prototype scale and analyses were performed by only varying the input seismic motion recorded at the base of each of seven centrifuge tests. Comparisons of numerical predictions with measured centrifuge test responses indicate that the analyses successfully capture the primary mechanisms of the system response. These included liquefaction in the free-field and development of negative pore pressures behind the wall, with accurate predictions of outward wall displacement for the majority of the tests. Most centrifuge tests and numerical predictions consistently exhibit a systematic linear trend of increase in wall displacements with spectral acceleration at the predominant frequency of the system. The numerical analyses overpredicted wall displacements only for centrifuge tests not following this trend, indicating that the variations maybe due to experimental variations from their specifications that were not considered in the blind predictions.

Trends in the texts of national anthems: A comparative study

In a recent previous investigation of national anthems, preferred topics and their bias (e.g., towards identity, fighting, or well-being) were identified subjectively (Silaghi-Dumitrescu, 2020). The present report aims to verify whether a more objective, automated, comparison of the texts of national anthems across the world can also reveal systematic trends – and to what extent. To this end, the Tropes and Semantria software packages are employed, revealing preferred topics (e.g., state, feeling, body, time, land, religion, family, fight), how their relative weights differ across continents and cultures, and how the conveyed sentiments vary. For instance, “liberty” is more common in Latin-country anthems while almost absent in Asia, “feelings” are less mentioned in Germanic-language anthems, and the first-person singular “I” is essentially absent African anthems. The sentiment scores of the anthems vary from neutral in Latin and Mediterranean anthems to much more positive in Central and Western Asian, Germanic and Slavic countries.

A constant N2H+ (1-0)-to-HCN (1-0) ratio on kiloparsec scales

Nitrogen hydrides such as NH3 and N2H+ are widely used by Galactic observers to trace the cold dense regions of the interstellar medium. In external galaxies, because of limited sensitivity, HCN has become the most common tracer of dense gas over large parts of galaxies. We provide the first systematic measurements of N2H+ (1-0) across different environments of an external spiral galaxy, NGC 6946. We find a strong correlation (r &gt; 0.98, p &lt; 0.01) between the HCN (1-0) and N2H+ (1-0) intensities across the inner ∼8 kpc of the galaxy, at kiloparsec scales. This correlation is equally strong between the ratios N2H+ (1-0)/CO (1-0) and HCN (1-0)/CO (1-0), tracers of dense gas fractions (fdense). We measure an average intensity ratio of N2H+ (1-0)/HCN (1-0) = 0.15 ± 0.02 over our set of five IRAM-30m pointings. These trends are further supported by existing measurements for Galactic and extragalactic sources. This narrow distribution in the average ratio suggests that the observed systematic trends found in kiloparsec-scale extragalactic studies of fdense and the efficiency of dense gas (SFEdense) would not change if we employed N2H+ (1-0) as a more direct tracer of dense gas. At kiloparsec scales our results indicate that the HCN (1-0) emission can be used to predict the expected N2H+ (1-0) over those regions. Our results suggest that, even if HCN (1-0) and N2H+ (1-0) trace different density regimes within molecular clouds, subcloud differences average out at kiloparsec scales, yielding the two tracers proportional to each other.