Thermally dominated deep mantle LLSVPs: A review

The two large low shear-wave velocity provinces (LLSVPs) that dominate lower-mantle structure may hold key information on Earth’s thermal and chemical evolution. It is generally accepted that these provinces are hotter than background mantle and are likely the main source of mantle plumes. Increasingly, it is also proposed that they hold a dense (primitive and/or recycled) compositional com- ponent. The principle evidence that LLSVPs may represent thermo-chemical ‘piles’ comes from seismic constraints, including: (i) their long-wavelength nature; (ii) sharp gradients in shear-wave velocity at their margins; (iii) non-Gaussian distributions of deep mantle shear-wave velocity anomalies; (iv) anti-correlated shear-wave and bulk-sound velocity anomalies (and elevated ratios between shear- and compressional-wave velocity anomalies); (v) anti-correlated shear-wave and density anomalies; and (vi) 1-D/radial profiles of seismic velocity that deviate from those expected for an isochemical, well-mixed mantle. In addition, it has been proposed that hotspots and the reconstructed eruption sites of large ig- neous provinces correlate in location with LLSVP margins. In this paper, we review recent results which indicate that the majority of these constraints do not require thermo-chemical piles: they are equally well (or poorly) explained by thermal heterogeneity alone. Our analyses and conclusions are largely based on comparisons between imaged seismic structure and synthetic seismic structures from a set of thermal and thermo-chemical mantle convection models, which are constrained by ∼ 300 Myr of plate motion histories. Modelled physical structure (temperature, pressure and composition) is converted into seismic velocities via a thermodynamic approach that accounts for elastic, anelastic and phase con- tributions and, subsequently, a tomographic resolution filter is applied to account for the damping and geographic bias inherent to seismic imaging. Our results indicate that, in terms of large-scale seismic structure and dynamics, these two provinces are predominantly thermal features and, accordingly, that chemical heterogeneity is largely a passive component of lowermost mantle dynamics

Sensitivity kernels for body tides on laterally heterogeneous planets based on adjoint methods

SUMMARY We apply the adjoint method to efficiently calculate the linearized sensitivity of body tide observations to perturbations in density, elastic/anelastic moduli and boundary topography. This theory is implemented practically within the context of normal mode coupling calculations, with an advantage of this approach being that much of the necessary technical machinery is present in existing coupling codes. A range of example sensitivity kernels are calculated relative to both spherically symmetric and laterally heterogeneous background models. These results reaffirm the conclusions of earlier studies that the M2 body tide is strongly sensitive to spherical harmonic degree-2 density variations at the base of the mantle. Moreover, it is found that the sensitivity kernels are only weakly dependent on the background model, and hence linearized methods are likely to be effective within inversions of body tide observations.NSF grant EAR-192386

Factors influencing attitudes toward vaccine safety and vaccine effectiveness amongst UK healthcare professionals prior to and at the time of COVID-19 vaccine rollout: Insights from the CoPE-HCP cohort study.

Given the potential for nosocomial outbreaks, we must understand factors associated with negative vaccine attitudes amongst healthcare professionals (HCPs) before the rollout of a newly developed vaccine in a pandemic setting. The aim of this prospective cohort study was to study the impact of preexisting and prevailing mental health on United Kingdom HCPs' attitudes towards a newly developed COVID-19 vaccine. Two online surveys were distributed: first during vaccine development (July-September, 2020) and second during nationwide vaccine rollout (December 2020-March 2021). Mental health (PHQ-9 for depression; GAD-7 for anxiety) was assessed in both surveys. Negative attitude regarding vaccine safety and vaccine effectiveness was assessed at vaccine rollout. A series of logistic regression models were developed relating mental health (preexisting during vaccine development, ongoing and new-onset during rollout, and changes in symptom severity) to negative vaccine attitudes. In 634 HCPs, the presence of depression and/or anxiety during vaccine development was associated with elevated negative attitude towards vaccine safety (adj. OR 1.74 [95% CI 1.10-2.75], p = .02), but not vaccine effectiveness (1.13 [0.77-1.66], p = .53) at rollout. This was independent of other characteristics: age, ethnicity, professional role, and history of contracting COVID-19. Ongoing depression and/or anxiety (1.72 [1.10-2.69], p = .02) was associated with elevated negative attitude regarding vaccine effectiveness, but not vaccine safety. Worsened combined symptom scores over time were associated with elevated negative vaccine effectiveness attitudes (1.03 [1.00-1.05], p < .05), but not vaccine safety. Overall, adverse mental health can impact on HCPs' attitudes towards a newly developed vaccine. Further work is required to understand how this translates to vaccine uptake

Anelasticity across seismic to tidal timescales: a self-consistent approach

In a pioneering study, Wahr & Bergen developed the widely adopted, pseudo-normal mode framework for predicting the impact of anelastic effects on the Earth's body tides. Lau $\textit{et al.}$ have recently derived an extended normal mode treatment of the problem (as well as a minor variant of the theory known as the direct solution method) that makes full use of theoretical developments in free oscillation seismology spanning the last quarter century and that avoids a series of assumptions and approximations adopted in the traditional theory for predicting anelastic effects. There are two noteworthy differences between these two theories: (1) the traditional theory only considers perturbations to the eigenmodes of an elastic Earth, whereas the new theory augments this set of modes to include the relaxation modes that arise in anelastic behaviour; and (2) the traditional theory approximates the complex perturbation to the tidal Love number as a scaled version of the complex perturbation to the elastic moduli, whereas the new theory computes the full complex perturbation to each eigenmode. In this study, we highlight the above differences using a series of synthetic calculations, and demonstrate that the traditional theory can introduce significant error in predictions of the complex perturbation to the Love numbers due to anelasticity and the related predictions of tidal lag angles. For the simplified Earth models we adopt, the computed lag angles differ by ∼20 per cent. The assumptions in the traditional theory have important implications for previous studies that use model predictions to correct observables for body tide signals or that analyse observations of body tide deformation to infer mantle anelastic structure. Finally, we also highlight the fundamental difference between apparent attenuation (i.e. attenuation inferred from observations or predicted using the above theories) and intrinsic attenuation (i.e. the material property investigated through experiments), where both are often expressed in terms of lag angles or $\textit{Q}$$^{-1}$. In particular, we demonstrate the potentially significant (factor of two or more) bias introduced in estimates of $\textit{Q}$$^{-1}$ and its frequency dependence in studies that have treated $\textit{Q}$$^{-1}$ determined from tidal phase lags or measured experimentally as being equal. The observed or theoretically predicted lag angle (or apparent $\textit{Q}$$^{-1}$) differs from the intrinsic, material property due to inertia, self-gravity and effects associated with the energy budget. By accounting for these differences we derive, for a special case, an expression that accurately maps apparent attenuation predicted using the extended normal mode formalism of Lau $\textit{et al.}$ into intrinsic attenuation. The theory allows for more generalized mappings which may be used to robustly connect observations and predictions of tidal lag angles to results from laboratory experiments of mantle materials.This work was supported by NSF EAR-1464024, NSF EAR-1215061, and Harvard University

The heritability of multi-modal connectivity in human brain activity

Patterns of intrinsic human brain activity exhibit a profile of functional connectivity that is associated with behaviour and cognitive performance, and deteriorates with disease. This paper investigates the relative importance of genetic factors and the common environment between twins in determining this functional connectivity profile. Using functional magnetic resonance imaging (fMRI) on 820 subjects from the Human Connectome Project, and magnetoencephalographic (MEG) recordings from a subset, the heritability of connectivity between 39 cortical regions was estimated. On average over all connections, genes account for about 15% of the observed variance in fMRI connectivity (and about 10% in alpha-band and 20% in beta-band oscillatory power synchronisation), which substantially exceeds the contribution from the environment shared between twins. Therefore, insofar as twins share a common upbringing, it appears that genes, rather than the developmental environment, play a dominant role in determining the coupling of neuronal activity

Defect passivation of transition metal dichalcogenides via a charge transfer van der Waals interface.

Integration of transition metal dichalcogenides (TMDs) into next-generation semiconductor platforms has been limited due to a lack of effective passivation techniques for defects in TMDs. The formation of an organic-inorganic van der Waals interface between a monolayer (ML) of titanyl phthalocyanine (TiOPc) and a ML of MoS2 is investigated as a defect passivation method. A strong negative charge transfer from MoS2 to TiOPc molecules is observed in scanning tunneling microscopy. As a result of the formation of a van der Waals interface, the ION/IOFF in back-gated MoS2 transistors increases by more than two orders of magnitude, whereas the degradation in the photoluminescence signal is suppressed. Density functional theory modeling reveals a van der Waals interaction that allows sufficient charge transfer to remove defect states in MoS2. The present organic-TMD interface is a model system to control the surface/interface states in TMDs by using charge transfer to a van der Waals bonded complex

Life history and chemical ecology of the Warrior wasp Synoeca septentrionalis (Hymenoptera : Vespidae, Epiponini)

Swarm-founding ‘Warrior wasps’ (Synoeca spp.) are found throughout the tropical regions of South America, are much feared due to their aggressive nest defence and painful sting. There are only five species of Synoeca, all construct distinctive nests that consist of a single sessile comb built onto the surface of a tree or rock face, which is covered by a ribbed envelope. Although locally common, research into this group is just starting. We studied eight colonies of Synoeca septentrionalis, a species recently been described from Brazil. A new colony is established by a swarm of 52 to 140 adults that constructs a colony containing around 200 brood cells. The largest colony collected containing 865 adults and over 1400 cells. The number of queen’s present among the eight colonies varied between 3 and 58 and no clear association between colony development and queen number was detected. Workers and queens were morphologically indistinguishable, but differences in their cuticular hydrocarbons were detected, particularly in their (Z)-9-alkenes. The simple cuticular profile, multiple queens, large size and small number of species makes the ‘Warrior wasps’ an excellent model group for further chemical ecology studies of swarm-founding wasps

Explaining informal payments for health services in Central and Eastern Europe: an institutional asymmetry perspective

The aim of this paper is to propose and evaluate a new institutional theory explanation for patients making informal payments for health services in Central and Eastern Europe. This views informal payments by patients to healthcare professionals as arising when formal institutional failures lead to an asymmetry between the laws and regulations of formal institutions and the unwritten rules of informal institutions. Reporting a 2013 Eurobarometer survey of the prevalence of informal payments by patients in Central and Eastern European countries, a strong association is revealed between the level of asymmetry between the formal and informal institutions, and the propensity to make informal payments. The association between informal payments and various formal institutional imperfections is then explored to evaluate which structural conditions might reduce this institutional asymmetry, and thus the propensity to make informal payments. The paper concludes by exploring the implications for tackling such informal practices