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We report observations of Rayleigh waves that orbit around Mars up to three times following the S1222a marsquake. Averaging these signals, we find the largest amplitude signals at 30 and 85 s central period, propagating with distinctly different group velocities of 2.9 and 3.8 km/s, respectively. The group velocities constraining the average crustal thickness beneath the great circle path rule out the majority of previous crustal models of Mars that have a >200 kg/m3 density contrast across the equatorial dichotomy between northern lowlands and southern highlands. We find that the thickness of the Martian crust is 42–56 km on average, and thus thicker than the crusts of the Earth and Moon. Considered with the context of thermal evolution models, a thick Martian crust suggests that the crust must contain 50%–70% of the total heat production to explain present‐day local melt zones in the interior of Mars. Plain Language Summary: The NASA InSight mission and its seismometer installed on the surface of Mars is retired after ∼4 years of operation. From the largest marsquake recording during the entire mission, we observe clear seismic signals from surface waves called Rayleigh waves that orbit around Mars up to three times. By measuring the wavespeeds with which these surface waves travel at different frequencies, we obtain the first seismic evidence that constrains the average crustal and uppermost mantle structures beneath the traveling path on a planetary scale. Using the new seismic observations together with gravity data, we confirm that the density of the crust in the northern lowlands and the southern highlands is similar, differing by no more than 200 kg/m3. Furthermore, we find that the global average crustal thickness on Mars is 42–56 km, much thicker than the Earth's and Moon's crusts. By exploring Mars' thermal history, a thick Martian crust requires about 50%–70% of the heat‐producing elements such as thorium, uranium, and potassium to be concentrated in the crust in order to explain local regions in the Martian mantle that can still undergo melting at present day. Key Points: We present the first observation of Rayleigh waves that orbit around Mars up to three timesGroup velocity measurements and 3‐D simulations constrain the average crustal and uppermost mantle velocities along the great‐circle propagation pathThe global average crustal thickness is 42–56 km and requires a large enrichment of heat‐producing elements to explain local melt zones [ABSTRACT FROM AUTHOR]

Adjoint waveform tomography (AWT) sits at the cutting edge of seismic tomography on local, regional, and global scales. However, the choice in starting model may have a significant impact on the final inversion results. In this paper, we present 3 AWT models of California that are based on different starting models. We chose three models that were inverted at different scales: SPiRaL, a global travel‐time tomography model (Simmons et al., 2021, 10.1093/gji/ggab277), CSEM_NA, a regional adjoint tomography model of North America and the North Atlantic (Krischer et al., 2018, 10.1029/2017JB015289), and WUS256, a regional adjoint tomography model of the western US (Rodgers et al., 2022, https://doi.org/10.1029/2022JB024549). We then inverted three AWT models using the same source and receiver set. We ran each model over three period bands: 30–100 s, 25–100 s, and 20–80 s. Once the iterations were finalized, we used five methods of testing model similarity in both the model and data space. We conclude that the choice of starting model has a minimal impact on long wavelength models if an appropriate multi‐scale inversion approach is used. Plain Language Summary: Seismic tomography uses earthquake records to resolve three‐dimensional models of seismic wavespeeds below Earth's surface. Full waveform inversion seeks to model the physics of wave propagation to create models that can most accurately reproduce the waveform data that are observed from recorded events. In this paper, we sought to study the effect of the choice of starting model on final inversion results in California using AWT, a type of Full waveform inversion technique; to our knowledge, this type of experiment has not been carried out before with real data at this scale. We began with three starting models that were created on different scales with different datasets. We then used five methods to compare the final model results. We focused on comparisons of the visual similarity of the models, the tectonic structures the models resolve, and how well the synthetic waveforms match the observed data. We find that the choice of starting model does not have a large impact when the model domain has azimuthally distributed events and stations over long length‐scales. Key Points: We present three adjoint waveform tomography models of California that each begin with a different starting modelThe three final models are compared using five metrics that span both the model space and data spaceBased on a conservative multi‐scale inversion approach, we conclude that the choice of starting model has minimal effect on the final model [ABSTRACT FROM AUTHOR]

We report a new model (WUS256) of radially anisotropic seismic wavespeeds of the crust and upper mantle of the western United States (WUS) obtained from adjoint waveform tomography for the purpose of improving synthetic waveform fits to observed data. WUS256 is based on inversion of over 94,000 waveforms from 72 earthquakes recorded by nearly 3,400 stations. We started with the SPiRaL global model (Simmons et al., 2021, https://doi.org/10.1093/gji/ggab277) and waveforms in the period band of 50–120 s. We followed a conservative multiscale inversion approach with eight stages and 256 total inversion iterations which enabled monotonic misfit reduction to 20‐s minimum‐period waves. WUS256 relied on time‐frequency (TF) phase misfits and a trust region limited memory Broyden–Fletcher–Goldfarb–Shanno (L‐BFGS) optimization. Hessian‐vector products were used to qualitatively assess model resolution. Results indicate that WUS256 has good coverage of the continental regions to depths of about 150 km and is able to resolve features on lateral scales of about 200 km. We quantify waveform fits by the reduction in TF and normalized amplitude difference misfits between WUS256 and the SPiRaL starting model. WUS256 significantly improves waveform fits with misfit reduction ≥ $\ge $64% for both inversion and validation data sets compared to the SPiRaL starting model and shows even better fits compared to other models. Waveform fits illustrate that WUS256 reproduces body‐waves, fundamental mode surface waves as well as late arriving dispersed and/or scattered short period surface waves. The improvement in waveform fit indicates that WUS256 can be used to reproduce path effects on regional complete waveforms and moment tensor inversions. Plain Language Summary: Seismic tomography is a method to infer the inaccessible three‐dimensional (3D) seismic material properties of the Earth, specifically the speeds of compressional and shear waves‐related compositional and temperature variations. It provides images of 3D structure that relate to plate tectonic processes as well as models to better represent seismic wave propagation through complex Earth structure. We report a new model of the 3D seismic structure for the upper 400 km of the Earth in the western United States (WUS). The model is obtained by a computationally intensive waveform inversion process that iteratively updates the sub‐surface model to improve the match to observed seismograms. High‐performance computing was used to run 256 model iterations for 72 earthquakes to fit nearly 100,000 seismograms. While other models of the WUS exist, this model is unique in that it is based on many more inversion iterations than previous models and provides much better fits to recorded seismograms. This model can be used to more accurately represent the effects of wave propagation through the Earth and enable more accurate estimates of seismic sources by accounting for wave propagation effects. Key Points: We report a new model of crustal and upper mantle seismic structure of the western United States (WUS) from adjoint waveform tomographyThe model (WUS256) is based on a conservative trust‐region limited memory Broyden–Fletcher–Goldfarb–Shanno (L‐BFGS) approach with many more iterations (256) than previous studiesWUS256 provides significantly improved waveform fits in the period band 20‐120 seconds relative to the starting and several other models [ABSTRACT FROM AUTHOR]

A gene expression study of mice treated with the tricyclic antidepressant amitriptyline was performed. To enable the detection of cell type-specific expression changes, laser-microdissected nucleus accumbens was analysed after 4 and 28 days of treatment. After 4 days of treatment no significantly regulated genes could be detected in this study. In contrast, 95 genes exhibited different expression levels in animals treated for 28 days with amitrityline compared with sham animals. This observation reflects the long-term effects and adaptation processes observed in patients treated with this drug. Among the regulated genes are receptors belonging to the dopamine-dependent signalling cascade, ion channels (mainly voltage-dependent potassium and calcium channels) potentially involved in signalling cascades and neuropeptides. The results support the hypothesis that the therapeutic effect of this antidepressant is much more complex and not confined to a reuptake inhibition of neurotransmitters. Paradigms inducing only weak expression changes, which may be limited to certain cell types within the highly complex brain structure, can therefore be reliably investigated by applying a cell type-specific expression profiling technique based on laser microdissection and subsequent RNA amplification followed by DNA microarray analysis. [ABSTRACT FROM AUTHOR]

The evolutionary histories and relationships among African, Eurasian, and Pacific Island populations are investigated by using observations on five polymorphic restriction sites in the beta-globin gene cluster. We present new data on 222 chromosomes from a global sample and combine these with previously published observations on 591 chromosomes. It is shown that the data are rich in rare haplotypes and that rare variants are not helpful for standard methods of population structure analysis. Consequently, a new approach is developed. We first consider the phylogeny of beta-globin haplotypes. The roles of mutation, gene conversion, and recombination in the generation of haplotype diversity are specifically focused upon. The relationships among human populations are then inferred from the phylogenetic relationships among the haplotypes, their presence or absence, and frequencies within populations. Questions regarding whether or not a phyletic process can account for relationships among the major geographical populations and whether or not an extant human population exhibits the qualities that would be expected of an ancestral group are addressed. The results of this analysis support an African origin for modern Homo sapiens and a phyletic structuring of the major geographical regions. However, it is shown that divergence times for the various populations cannot be determined from these data.