Metals from spacecraft reentry in stratospheric aerosol particles.

Large increases in the number of low earth orbit satellites are projected in the coming decades [L. Schulz, K.-H. Glassmeier, Adv. Space Res. 67, 1002-1025 (2021)] with perhaps 50,000 additional satellites in orbit by 2030 [GAO, Large constellations of satellites: Mitigating environmental and other effects (2022)]. When spent rocket bodies and defunct satellites reenter the atmosphere, they produce metal vapors that condense into aerosol particles that descend into the stratosphere. So far, models of spacecraft reentry have focused on understanding the hazard presented by objects that survive to the surface rather than on the fate of the metals that vaporize. Here, we show that metals that vaporized during spacecraft reentries can be clearly measured in stratospheric sulfuric acid particles. Over 20 elements from reentry were detected and were present in ratios consistent with alloys used in spacecraft. The mass of lithium, aluminum, copper, and lead from the reentry of spacecraft was found to exceed the cosmic dust influx of those metals. About 10% of stratospheric sulfuric acid particles larger than 120 nm in diameter contain aluminum and other elements from spacecraft reentry. Planned increases in the number of low earth orbit satellites within the next few decades could cause up to half of stratospheric sulfuric acid particles to contain metals from reentry. The influence of this level of metallic content on the properties of stratospheric aerosol is unknown.

Design and testing of a sew-free origami mask for improvised respiratory protection.

Respiratory aerosols with diameters smaller than 100µm have been confirmed as important vectors for the spread of diseases such as SARS-CoV-2. While disposable and cloth masks afford some protection, they are typically inefficient at filtering these aerosols and require specialized fabrication devices to produce. We describe a fabrication technique that makes use of a folding procedure (origami) to transform any filtration material into a mask. These origami masks can be fabricated by non-experts at minimal cost and effort, provide adequate filtration efficiencies, and are easily scaled to different facial sizes. Using a mannequin fit test simulator, we demonstrate that these masks can provide filtration efficiencies of over 90% while simultaneously providing greater comfort as demonstrated by pressure drops of <20 Pa. We also quantify mask leakage by measuring the variations in filtration efficiency and pressure drop when masks are sealed to the mannequin face compared to when the mask is unsealed but positioned to achieve the best fit. While leakage generally trended with pressure drop, some of the best performing mask media achieved <10% reduction in filtration efficiency due to leakage. Because this mask can provide high filtration efficiencies at low pressure drop compared to commercial alternatives, it is likely to promote greater mask wearing tolerance and acceptance.

Evidence for a vestigial nematic state in the cuprate pseudogap phase.

The CuO2 antiferromagnetic insulator is transformed by hole-doping into an exotic quantum fluid usually referred to as the pseudogap (PG) phase. Its defining characteristic is a strong suppression of the electronic density-of-states D(E) for energies |E| < [Formula: see text], where [Formula: see text] is the PG energy. Unanticipated broken-symmetry phases have been detected by a wide variety of techniques in the PG regime, most significantly a finite-Q density-wave (DW) state and a Q = 0 nematic (NE) state. Sublattice-phase-resolved imaging of electronic structure allows the doping and energy dependence of these distinct broken-symmetry states to be visualized simultaneously. Using this approach, we show that even though their reported ordering temperatures T DW and T NE are unrelated to each other, both the DW and NE states always exhibit their maximum spectral intensity at the same energy, and using independent measurements that this is the PG energy [Formula: see text] Moreover, no new energy-gap opening coincides with the appearance of the DW state (which should theoretically open an energy gap on the Fermi surface), while the observed PG opening coincides with the appearance of the NE state (which should theoretically be incapable of opening a Fermi-surface gap). We demonstrate how this perplexing phenomenology of thermal transitions and energy-gap opening at the breaking of two highly distinct symmetries may be understood as the natural consequence of a vestigial nematic state within the pseudogap phase of Bi2Sr2CaCu2O8.

Topology in Nonlinear Mechanical Systems.

Many advancements have been made in the field of topological mechanics. The majority of the work, however, concerns the topological invariant in a linear theory. In this Letter, we present a generic prescription to define topological indices that accommodates nonlinear effects in mechanical systems without taking any approximation. Invoking the tools of differential geometry, a Z-valued quantity in terms of a topological index in differential geometry known as the Poincaré-Hopf index, which features the topological invariant of nonlinear zero modes (ZMs), is predicted. We further identify one type of topologically protected solitons that are robust to disorders. Our prescription constitutes a new direction of searching for novel topologically protected nonlinear ZMs in the future.

Composition of Ultrafine Particles in Urban Beijing: Measurement Using a Thermal Desorption Chemical Ionization Mass Spectrometer.

Ultrafine particles (UFPs) dominate the particle number population in the urban atmosphere and revealing their chemical composition is important. The thermal desorption chemical ionization mass spectrometer (TDCIMS) can semicontinuously measure UFP composition at the molecular level. We modified a TDCIMS and deployed it in urban Beijing. Radioactive materials in the TDCIMS for aerosol charging and chemical ionization were replaced by soft X-ray ionizers so that it can be operated in countries with tight regulations on radioactive materials. Protonated N-methyl-2-pyrrolidone ions were used as the positive reagent ion, which selectively detects ammonia and low-molecular weight-aliphatic amines and amides vaporized from the particle phase. With superoxide as the negative reagent ion, a wide range of inorganic and organic compounds were observed, including nitrate, sulfate, aliphatic acids with carbon numbers up to 18, and highly oxygenated CHO, CHON, and CHOS compounds. The latter two can be attributed to parent ions or the decomposition products of organonitrates and organosulfates/organosulfonates, respectively. Components from both primary emissions and secondary formation of UFPs were identified. Compared to the UFPs measured at forest and marine sites, those in urban Beijing contain more nitrogen-containing and sulfur-containing compounds. These observations illustrate unique features of the UFPs in the urban environment and provide insights into their origins.

Multilevel Analysis of Child and Adolescent Subjective Well-Being Across 14 Countries: Child- and Country-Level Predictors.

This study tests an ecological, relationship-based model of children's subjective well-being with 9- to 14-year-old children (n = 25,906) from 14 countries across Africa, Asia, Europe, North America, and South America. Children completed the Children's Worlds survey, a self-report measure of contextual and well-being indicators. Multilevel modeling was used to predict children's well-being (life satisfaction and self-image) at two levels, child (age, gender, home context, family relationships, peer relationships, school context, teacher relationships, and neighborhood quality), and country (gross domestic product and income inequality). Findings indicated that intercepts varied significantly across countries. The majority of variance in children's well-being was attributed to child-level rather than country-level factors. Country-level factors did not strongly predict well-being but marginally improved model fit.

Commensurate 4a0-period charge density modulations throughout the Bi2Sr2CaCu2O8+x pseudogap regime.

Theories based upon strong real space (r-space) electron-electron interactions have long predicted that unidirectional charge density modulations (CDMs) with four-unit-cell (4a0) periodicity should occur in the hole-doped cuprate Mott insulator (MI). Experimentally, however, increasing the hole density p is reported to cause the conventionally defined wavevector QA of the CDM to evolve continuously as if driven primarily by momentum-space (k-space) effects. Here we introduce phase-resolved electronic structure visualization for determination of the cuprate CDM wavevector. Remarkably, this technique reveals a virtually doping-independent locking of the local CDM wavevector at [Formula: see text] throughout the underdoped phase diagram of the canonical cuprate Bi2Sr2CaCu2O8 These observations have significant fundamental consequences because they are orthogonal to a k-space (Fermi-surface)-based picture of the cuprate CDMs but are consistent with strong-coupling r-space-based theories. Our findings imply that it is the latter that provides the intrinsic organizational principle for the cuprate CDM state.

Identifying risk and protective factors related to depressive symptoms among Northern Plains American Indian women cancer survivors.

Cancer is the leading cause of death among American Indian and Alaska Native (AIAN) women, and depressive symptoms have been linked to higher mortality, but research on depressive symptoms among AIAN cancer patients has been scant. The purpose of this exploratory study was, using the Framework of Historical Oppression, Resilience, and Transcendence, to examine risk and protective factors related to depressive symptoms in American Indian (AI) women cancer survivors. We examined the relationships of adverse childhood experiences (ACE), perceived health status, resilience, and social support with depressive symptoms in Northern Plains AI women cancer survivors. We used a cross-sectional design with purposive sampling of 73 female cancer survivors (aged 18 years or older) between June 2014 and February 2015. Hierarchical multiple regression was used to test three sets of variables in relation to depressive symptoms: (1) sociodemographics, (2) risk factors (ACE and perceived health), and (3) protective factors (psychological resilience and social support). Approximately 47 percent of participants had probable depressive symptoms. Depressive symptoms were inversely associated with perceived health, psychological resilience, and social support. These results support bolstering existing social support among AI cancer patients and survivors as well as prevention and intervention efforts that strengthen resilience.

Quantum Spin Liquid Intertwining Nematic and Superconducting Order in Fese.

Despite its seemingly simple composition and structure, the pairing mechanism of FeSe remains an open problem due to several striking phenomena. Among them are nematic order without magnetic order, nodeless gap and unusual inelastic neutron spectra with a broad continuum, and gap anisotropy consistent with orbital selection of unknown origin. Here we propose a microscopic description of a nematic quantum spin liquid that reproduces key features of neutron spectra. We then study how the spin fluctuations of the local moments lead to pairing within a spin-fermion model. We find the resulting superconducting order parameter to be nodeless s±d wave within each domain. Further we show that orbital dependent Kondo-like coupling can readily capture observed gap anisotropy. Our prediction calls for inelastic neutron scattering in a detwinned sample.

Coherent Superconductivity with a Large Gap Ratio from Incoherent Metals.

A mysterious incoherent metallic (IM) normal state with T-linear resistivity is ubiquitous among strongly correlated superconductors. Recent progress with microscopic models exhibiting IM transport has presented the opportunity for us to study new models that exhibit direct transitions into a superconducting state out of IM states within the framework of connected Sachdev-Ye-Kitaev "quantum dots." Here, local Sachdev-Ye-Kitaev interactions within a dot produce IM transport in the normal state, while local attractive interactions drive superconductivity. Through explicit calculations, we find two features of superconductivity arising from an IM normal state. First, despite the absence of quasiparticles in the normal state, the superconducting state still exhibits coherent superfluid transport. Second, the nonquasiparticle nature of the IM Green's functions produces a large enhancement in the ratio of the zero-temperature superconducting gap Δ and transition temperature T_{SC}, 2Δ/T_{SC}, with respect to its BCS value of 3.53.

Topology and Geometry of Spin Origami.

Kagome antiferromagnets are known to be highly frustrated and degenerate when they possess simple, isotropic interactions. We consider the entire class of these magnets when their interactions are spatially anisotropic. We do so by identifying a certain class of systems whose degenerate ground states can be mapped onto the folding motions of a generalized "spin origami" two-dimensional mechanical sheet. Some such anisotropic spin systems, including Cs_{2}ZrCu_{3}F_{12}, map onto flat origami sheets, possessing extensive degeneracy similar to isotropic systems. Others, such as Cs_{2}CeCu_{3}F_{12}, can be mapped onto sheets with nonzero Gaussian curvature, leading to more mechanically stable corrugated surfaces. Remarkably, even such distortions do not always lift the entire degeneracy, instead permitting a large but subextensive space of zero-energy modes. We show that for Cs_{2}CeCu_{3}F_{12}, due to an additional point group symmetry associated with the structure, these modes are "Dirac" line nodes with a double degeneracy protected by a topological invariant. The existence of mechanical analogs thus serves to identify and explicate the robust degeneracy of the spin systems.

Direct phase-sensitive identification of a d-form factor density wave in underdoped cuprates.

The identity of the fundamental broken symmetry (if any) in the underdoped cuprates is unresolved. However, evidence has been accumulating that this state may be an unconventional density wave. Here we carry out site-specific measurements within each CuO2 unit cell, segregating the results into three separate electronic structure images containing only the Cu sites [Cu(r)] and only the x/y axis O sites [Ox(r) and O(y)(r)]. Phase-resolved Fourier analysis reveals directly that the modulations in the O(x)(r) and O(y)(r) sublattice images consistently exhibit a relative phase of π. We confirm this discovery on two highly distinct cuprate compounds, ruling out tunnel matrix-element and materials-specific systematics. These observations demonstrate by direct sublattice phase-resolved visualization that the density wave found in underdoped cuprates consists of modulations of the intraunit-cell states that exhibit a predominantly d-symmetry form factor.

Risk and protective factors for depressive symptoms among American Indian older adults: adverse childhood experiences and social support.

OBJECTIVES: Despite efforts to promote health equity, many American Indian and Alaska Native (AI/AN) populations, including older adults, experience elevated levels of depression. Although adverse childhood experiences (ACE) and social support are well-documented risk and protective factors for depression in the general population, little is known about AI/AN populations, especially older adults. The purpose of this study was to examine factors related to depression among a sample of AI older adults in the midwest. METHOD: Data were collected using a self-administered survey completed by 233 AIs over the age of 50. The survey included standardized measures such as the Geriatric Depression Scale-Short Form, ACE Questionnaire, and the Multidimensional Scale of Perceived Social Support. Hierarchical multivariate regression analyses were conducted to evaluate the main hypotheses of the study. RESULTS: Two dimensions of ACE (i.e., childhood neglect, household dysfunction) were positively associated with depressive symptoms; social support was negatively associated with depressive symptoms. Perceived health and living alone were also significant predictors. CONCLUSION: ACE may play a significant role in depression among AI/AN across the life course and into old age. Social support offers a promising mechanism to bolster resilience among AI/AN older adults.

Secondary organic aerosol formation and organic nitrate yield from NO3 oxidation of biogenic hydrocarbons.

The secondary organic aerosol (SOA) mass yields from NO3 oxidation of a series of biogenic volatile organic compounds (BVOCs), consisting of five monoterpenes and one sesquiterpene (α-pinene, ß-pinene, Δ-3-carene, limonene, sabinene, and ß-caryophyllene), were investigated in a series of continuous flow experiments in a 10 m(3) indoor Teflon chamber. By making in situ measurements of the nitrate radical and employing a kinetics box model, we generate time-dependent yield curves as a function of reacted BVOC. SOA yields varied dramatically among the different BVOCs, from zero for α-pinene to 38-65% for Δ-3-carene and 86% for ß-caryophyllene at mass loading of 10 µg m(-3), suggesting that model mechanisms that treat all NO3 + monoterpene reactions equally will lead to errors in predicted SOA depending on each location's mix of BVOC emissions. In most cases, organonitrate is a dominant component of the aerosol produced, but in the case of α-pinene, little organonitrate and no aerosol is formed.

Insight into acid-base nucleation experiments by comparison of the chemical composition of positive, negative, and neutral clusters.

We investigated the nucleation of sulfuric acid together with two bases (ammonia and dimethylamine), at the CLOUD chamber at CERN. The chemical composition of positive, negative, and neutral clusters was studied using three Atmospheric Pressure interface-Time Of Flight (APi-TOF) mass spectrometers: two were operated in positive and negative mode to detect the chamber ions, while the third was equipped with a nitrate ion chemical ionization source allowing detection of neutral clusters. Taking into account the possible fragmentation that can happen during the charging of the ions or within the first stage of the mass spectrometer, the cluster formation proceeded via essentially one-to-one acid-base addition for all of the clusters, independent of the type of the base. For the positive clusters, the charge is carried by one excess protonated base, while for the negative clusters it is carried by a deprotonated acid; the same is true for the neutral clusters after these have been ionized. During the experiments involving sulfuric acid and dimethylamine, it was possible to study the appearance time for all the clusters (positive, negative, and neutral). It appeared that, after the formation of the clusters containing three molecules of sulfuric acid, the clusters grow at a similar speed, independent of their charge. The growth rate is then probably limited by the arrival rate of sulfuric acid or cluster-cluster collision.

Striped spin liquid crystal ground state instability of kagome antiferromagnets.

The Dirac spin liquid ground state of the spin 1/2 Heisenberg kagome antiferromagnet has potential instabilities. This has been suggested as the reason why it does not emerge as the ground state in large-scale numerical calculations. However, previous attempts to observe these instabilities have failed. We report on the discovery of a projected BCS state with lower energy than the projected Dirac spin liquid state which provides new insight into the stability of the ground state of the kagome antiferromagnet. The new state has three remarkable features. First, it breaks spatial symmetry in an unusual way that may leave spinons deconfined along one direction. Second, it breaks the U(1) gauge symmetry down to Z(2). Third, it has the spatial symmetry of a previously proposed "monopole" suggesting that it is an instability of the Dirac spin liquid. The state described herein also shares a remarkable similarity to the distortion of the kagome lattice observed at low Zn concentrations in Zn-paratacamite and in recently grown single crystals of volborthite suggesting it may already be realized in these materials.

Integrating High-Value Care Concepts into Preclinical Medical Education: A Practical Approach.

Objectives: Although some US medical schools have incorporated high-value care into their preclinical curriculum, there is no standardized approach and major curricular overhaul can be prohibitively onerous. The objectives of this study were to develop a feasible and effective high-value care curriculum, integrate it into an existing pre-clinical course, and assess student and faculty perceptions of the educational value of the curriculum. Methods: Between 2019 and 2021, University of Vermont preclinical medical students participating in the Students & Trainees Advocating for Resource Stewardship (STARS) program collaborated with the faculty director of the preclinical pathophysiology course to identify Choosing Wisely® recommendations relevant to course topics. For each recommendation, STARS students created a case-based, multiple-choice question, answer key and rationale to accompany standard course materials. At each year's course completion, participating students and faculty were invited to complete a survey to assess their perceptions of the curriculum. Results: Seventeen case-based questions were integrated into existing pathophysiology course sessions each year. Over the 3-year period, 420 students and 35 teaching faculty participated in the course, and 171 (40.7%) students and 24 (68.6%) faculty completed the post-course survey. Among student respondents, 80% agreed the curriculum increased their awareness of high-value care, 79% agreed they would be more likely to apply high-value care concepts during their medical career, and 92% agreed it was valuable to discuss Choosing Wisely® recommendations during the second year of medical school. Conclusion: A student-led initiative to incorporate high-value care content within an existing pre-clinical course was well-received by medical students, who reported increased awareness of and intention to apply high-value care principles. This model may offer a feasible and effective approach to high-value care education in the absence of an extensive formal curriculum.

Diastereoselective construction of syn-1,3-dioxanes via a bismuth-mediated two-component hemiacetal/oxa-conjugate addition reaction.

The bismuth-mediated two-component hemiacetal/oxa-conjugate addition of δ-trialkylsilyloxy and δ-hydroxy α,ß-unsaturated aldehydes and ketones with alkyl aldehydes provides the syn-1,3-dioxanes in a highly efficient and stereoselective manner. The key advantages of this protocol are its operational simplicity and its ability to directly access electron-withdrawing groups without recourse to oxidation state adjustments.

Science, practice, and policy related to adverse childhood experiences: Framing the conversation.

Adverse childhood experiences (ACEs) detrimentally affect health outcomes in childhood, adolescence, and adulthood. Over the past 2 decades, the recognition of ACEs by scientists and professionals across disciplines, policymakers, and the public has evolved and expanded. Although the initial articulation of ACEs in Felitti et al.'s landmark study has formed the basis of subsequent investigations on the long-term impact of childhood adversities on health and health risk behaviors, a wider public health framework, inclusive of psychology and other social sciences, also shapes current conceptualizations, research, practice, and policies. This article provides an overview of the special issue Adverse Childhood Experiences: Translating Research to Action. Given the rapid expansion and widespread application of ACEs, this special issue was developed to articulate critical concepts, to demonstrate the significance and relevance of psychological research and practice, and to catalyze further efforts to develop effective programs and policies informed by science. The 15 articles included reflect the continuum of critical work being conducted in research, practice, intervention and prevention programs, and public policy and serve to synthesize the growing body of empirical evidence. The overarching themes that emerged are framed as 3 essential questions: (a) How broadly should ACEs be defined?, (b) How should ACEs be assessed?, and (c) How can ACEs science translate into high quality services? As illustrated in these articles, policy and practice applications deriving from psychology as a hub science can substantially benefit the health and mental health of children, adolescents, and adults. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Validating the eHealth Literacy Scale in Rural Adolescents.

PURPOSE: Given that the recent eHealth literacy literature supports the properties of the 3-factor eHealth literacy scale (eHEALS) model in samples with millennials, adults, and older adults, the appropriate next step is to establish whether the model can be reproduced in a rural adolescent sample. The purpose of this study was to evaluate the recent 3-factor model by Paige and associates with a sample of seventh-grade students. METHODS: This cross-sectional study included a subsample of students (n = 146) from 3 school districts in Appalachian Kentucky. We used confirmatory factor analysis (CFA) procedures and small sample model fit guidelines to evaluate our model, and the 1-sample bootstrap algorithm with bias-corrected and accelerated 95% confidence intervals to estimate associations among eHEALS and health and technology variables. FINDINGS: A total of 137 students, or 61% of enrolled seventh-grade students, completed the study. CFA results showed eHEALS 3-factor loadings-information awareness, information seeking, and information engagement-were high (≥0.63) and statistically significant. We observed evidence of a good model fit (root mean square error of approximation [RMSEA] = 0.07, standardized root mean square residual [SRMR] = 0.03, comparative fit index [CFI] = 0.99) and results are comparable with Paige and associates' model fit (RMSEA = 0.06, SRMR = 0.08, CFI = 0.98). Correlations showed that students with more access to technology were associated with higher information seeking (r = 0.31) and higher information engagement (r = 0.23). eHealth literacy scores did not differ by level of rurality or gender. CONCLUSIONS: The 3-factor eHEALS is a reliable and valid instrument in assessing eHealth literacy in a group of rural seventh graders from Appalachian Kentucky.