Differential Extinction Research Articles

The Galactic Center in Color: Measuring Extinction with High-proper-motion Stars

The Milky Way’s central parsec is a highly extinguished region with a population of high-proper-motion stars. We have tracked 145 stars for ∼10 yr at wavelengths between 1 and 4 μm to analyze extinction effects in color–magnitude space. Approximately 30% of this sample dims and reddens over the course of years, likely from the motion of sources relative to an inhomogeneous screen of dust. We correct previous measurements of the intrinsic variability fraction for differential extinction effects, resulting in a reduced stellar variability fraction of 34%. The extinction variability subsample shows that the extinguishing material has subarcsecond scales, much smaller variations than previously reported. The observed extinction events imply a typical cross section of 500 au and a density of around 3 × 104 atoms cm−3 for the extinguishing material, which are consistent with measurements of filamentary dust and gas at the Galactic center. Furthermore, given that the stars showing extinction variability tend to be more highly reddened than the rest of the sample, the extinction changes are likely due to material localized to the Galactic center region. We estimate the relative extinction between 1 and 4 μm as AH:AK′:AL′=1.67±0.05:1:0.69±0.03 . Our measurement of extinction at longer wavelengths—L’ (3.8 μm)—is inconsistent with recent estimations of the integrated extinction toward the central parsec. One interpretation of this difference is that the dust variations this experiment are sensitive to—which are local to the Galactic center—are dominated by grains of larger radius than the foreground.

A Rare Cepheid-hosting Open Cluster Triad in Sagittarius

The following Galactic star clusters may constitute a rare Cepheid hosting triad in Sagittarius: M25, NGC 6716, and Collinder 394. The open clusters have comparable ages (τ ≃ 80 Myr) and nearly aligned main-sequences and turnoffs after accounting for differential extinction (A G , EBP−RP ). Gaia DR3 astrometry confirms an association between the three clusters, and importantly, the classical Cepheid U Sgr is a member (P ≃ 6.ͩ75, τ ≃ 80 Myr), while DR3 data indicate that the classical Cepheid BB Sgr (P ≃ 6.ͩ64, τ ≃ 80 Myr) could possibly be an escaped member traversing the background field.

The rise and fall of notoungulates: How Andean uplift, available land area, competition, and depredation driven its diversification dynamics

Unraveling the biotic and abiotic drivers likely influencing clades’ diversification dynamics (differential speciation and extinction rates) is crucial for understanding life on Earth. Here, we present a comprehensive analysis of the diversification dynamics of notoungulates (Mammalia: Notoungulata), the most diverse and widespread Cenozoic herbivore mammals that evolved in South America (SA) but are now entirely extinct. Employing fossil occurrences restricted to the southern part of the SA and a Bayesian framework, we examined the historical speciation and extinction rates across all notoungulates, suborders, and three body size categories and tested whether these dynamics could be driven by biotic (e.g., diversity dependence, competition) and abiotic (e.g., Andean uplift and temperature changes) factors. Our findings reveal significant variability in diversification rates over time and groups driven by biotic and abiotic factors. We observed an increase in notoungulate speciation rates correlated with lower group self-diversity, likely related to limited environmental productivity and more extensive emerged continental areas that can provide increased environmental and ecological heterogeneity. In contrast, elevated extinction rates were correlated with intensified Andean uplift events, which can trigger landscape modifications and the arrival of placental carnivores after the Great American Biotic Interchange, probably due to notoungulate vulnerability to novel predation pressures. Furthermore, sparassodont diversity appears to increase speciation and extinction rates of notoungulates, although the direct mechanism relating them remains uncertain. The heterogeneity in the observed patterns of speciation and extinction across distinct size categories and taxonomic clades provides valuable perspectives on how ancient global and regional changes impacted the diversification dynamics of mammals and underscores the intricate interplay between environmental changes and biological interactions in shaping the evolution of life on Earth.

Exogenous glucocorticoids to improve extinction learning for post-traumatic stress disorder patients with hypothalamic–pituitary–adrenal-axis dysregulation: a study protocol description

ABSTRACT Background: Trauma-focused treatments for post-traumatic stress disorder (PTSD) are effective for many patients. However, relapse may occur when acquired extinction memories fail to generalize beyond treatment contexts. A subgroup of PTSD patients – potentially with substantial exposure to early-life adversity (ELA) – show dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis, which results in lower cortisol levels. Glucocorticoids, including cortisol, appear to facilitate strength and generalization of emotional memories. Objective: We describe the protocol of an integrated PTSD study. We investigate (A) associations between HPA-axis dysregulation, ELA, epigenetic markers, and PTSD treatment outcome (observational study); and (B) effects of exogenous glucocorticoids on strength and generalization of extinction memories and associated neural mechanisms [pharmacological intervention study with functional magnetic resonance imaging (fMRI)]. The objective is to provide proof of concept that PTSD patients with HPA-axis dysregulation often experienced ELA and may show improved strength and generalization of extinction learning after glucocorticoid administration. Method: The observational study (n = 160 PTSD group, n = 30 control group) assesses ELA, follow-up PTSD symptoms, epigenetic markers, and HPA-axis characteristics (salivary cortisol levels during low-dose dexamethasone suppression test and socially evaluated cold-pressor test). The pharmacological intervention study (n = 80 PTSD group, with and without HPA-axis dysregulation) is a placebo-controlled fMRI study with a crossover design. To investigate strength and generalization of extinction memories, we use a differential fear acquisition, extinction, and extinction recall task with spatial contexts within a virtual environment. Prior to extinction learning, 20 mg hydrocortisone or placebo is administered. During next-day recall, strength of the extinction memory is determined by recovery of skin conductance and pupil dilation differential responding, whereas generalization is assessed by comparing responses between different spatial contexts. Conclusion: The integrated study described in the current protocol paper could inform a personalized treatment approach in which these PTSD patients may receive glucocorticoids as a treatment enhancer in trauma-focused therapies. Trial registration: The research project is registered in the European Union Drug Regulating Authorities Clinical Trials (EudraCT) database, https://eudract.ema.europa.eu/, EudraCT number 2020-000712-30.

Towards a More General Theory of Evolution by Natural Selection: A Manifesto

In this manifesto for a more comprehensive account of evolution by natural selection (ENS), we draw on Hull’s framework to expand the reach of Darwinian explanations. His approach is centered on the notions of interactor and replicator. He (and many others following him) defines the interactor in terms of cohesiveness. Often, such cohesiveness is cashed out by the vertical transmission to the next generation of the replicators that constitute the interactors. While we maintain the importance of the reciprocal influence of interactors and replicators (the differential extinction and proliferation of interactors leads to the differential extinction and proliferation of the replicators that produce them) central to Hull’s framework, we downplay the importance of the cohesiveness of interactors and eliminate any need for lineage formation among them. This suggested revision of the interactor synthesizes various recent contributions in the field, and it allows the interactor/replicator framework to tackle more complex entities. Our approach, however, stands in stark opposition to the classical approach to ENS centered on lineage formation. In this paper, we present our view and argue that it should replace the classical approach in structuring future work in evolutionary biology.

Selection by differential survival among marine animals in the Phanerozoic

The Gaia hypothesis posits that the Earth and its biosphere function as a single self-stabilizing system, but a key challenge is explaining how this could have arisen through Darwinian evolution. One theory is that of “selection by differential survival,” in which a clade’s extinction probability decreases with age as it accumulates adaptations resisting environmental disturbances. While this is hard to assess during early Earth history, we can assess whether this process operated among marine animal genera throughout the Phanerozoic. To that end, we analyzed time ranges of 36,117 extinct animal genera using fossil occurrence data from the Paleobiology Database in order to calculate marine metazoan extinction age selectivity, extinction rates, and speciation rates over the Phanerozoic. We identify four signatures of selection by differential survival: lower extinction rates among older lineages, heritability and taxonomically nested propagation of extinction resistance, reduced age selectivity during rare environmental perturbations, and differential extinction rather than speciation as the primary driver of the phenomenon. Evidence for this process at lower taxonomic levels also implies its possibility for life as a whole – indeed, the possibility of Gaia.

Peeling back the layers of extinction of dusty galaxies in the era of JWST: modelling joint NIRSpec + MIRI spectra at rest-frame 1.5–28 μm

ABSTRACT We present an analysis of the combined NIRSpec and MIRI spectra of dusty galaxies between 1.5 and 28 $\mu$m rest-frame by implementing a differential extinction model, where the strength of extinction varies across the spectrum as different layers of the obscuring dust are probed. Our model is able to recover a 2D distribution of dust temperature and extinction, which allows inference of the physical nature of the dust in these environments. We show that differential extinction is necessary to reproduce the spectra of four highly obscured Luminous Infrared Galaxies observed with NIRSpec IFU and MIRI MRS, where simple screen or uniformly mixed dust distributions fail to fit the data. We additionally compare the extinction of H ii regions in these galaxies via hydrogen recombination lines, the extinction of molecular gas via the H2 lines, polycyclic aromatic hydrocarbons via the 12.7/11.3 PAH ratio and the stellar continuum. We find that the molecular gas is deeply buried with the H ii regions in star-forming regions, with a similar extinction to the hottest dust components. However, we find the cooler dust to be less obscured, at a similar extinction to the stellar continuum and PAHs. The nuclei show a complex dust distribution with VV114 NE, NGC 3256 S, and IIZw96 SW, showing a deeply buried continuum source relative to the molecular gas/H ii regions. Additionally, NGC 3256 S, NGC 7469, and VV114 SW show an isolated hot dust component, indicative of AGN heating, where NGC 3256 S and NGC 7469 are previously known as AGN.

A multi-modal assessment of fear conditioning in adolescent anorexia nervosa.

Anorexia nervosa (AN) is a pernicious psychiatric disorder which is principally characterized by a fear of weight gain. Notwithstanding the centrality of fear in the psychopathology of AN, controlled assessments of negative valence systems are lacking. Herein we assess fear conditioning in adolescent females with AN. Adolescent girls (Mage = 14.6 years, ±1.57) with DSM-5 diagnoses of AN (N = 25) and age-matched control girls (Mage = 14.8 years, ±1.46) with no DSM-5 diagnoses (N = 25) completed structured clinical interviews and participated in a classical three-phase Pavlovian fear conditioning paradigm. Participants with comorbid anxiety disorders were excluded. Skin conductance response (SCR) was measured, alongside self-reported fear, valence, and fear expectancy ratings. Both groups demonstrated significant differential acquisition across all four measures. Regarding group comparisons, no differences emerged for self-reported fear, valence, and fear expectancy ratings during acquisition, although for SCR, those with AN demonstrated reduced physiological arousal relative to controls. Both groups demonstrated significant differential extinction for unconditioned stimuli (US) expectancy, self-report fear, and self-report valence. No statistically significant group differences were evident during extinction to the conditioned stimuli (CS)+, on any outcome measure. However, controls reported more positive valence to the CS- than those with AN. Contrary to our hypotheses, our preliminary assessment did not find support for elevated fear responding among adolescent girls with AN with regards to fear acquisition or extinction. These data suggest that AN in adolescent girls may not be associated with a heightened propensity to acquire fear, but conversely, may suggest that exposure treatments for AN may be helpful, since extinction learning is intact in AN. AN is characterized by fear-related symptoms, including food and weight-related fear, and behavioral avoidance, yet controlled studies assessing fear learning are limited. Our preliminary assessment of adolescent AN indicates no abnormalities in fear learning among adolescents with AN. These findings may inform existing mechanistic models of AN psychopathology, and the development of exposure-based treatments for AN.

New Interstellar Extinction Maps Based on Gaia and Other Sky Surveys

We present new three-dimensional (3D) interstellar extinctionmaps in the V and Gaia G filterswithin 2 kpc of the Sun, a 3D differential extinction (dust density) map along the line of sight in the samespace, a 3D map of variations in the ratio of the extinctions in the V and Gaia G filters within 800 pcof the Sun, and a 2D map of total Galactic extinction through the entire dust half-layer from the Sun toextragalactic space for Galactic latitudes |b| 13◦. The 3D maps have a transverse resolution from 3.6to 11.6 pc and a radial resolution of 50 pc. The 2D map has an angular resolution of 6.1 arcmin. Wehave produced these maps based on the Gaia DR3 parallaxes and Gaia, Pan-STARRS1, SkyMapper,2MASS, andWISE photometry for ∼ 100 million stars. We have paid special attention to the space within200 pc of the Sun and high Galactic latitudes as regions where the extinction estimates have had a largerelative uncertainty so far. Our maps estimate the extinction within the Galactic dust layer from the Sunto an extended object or through the entire dust half-layer from the Sun to extragalactic space with anaccuracy σ(AV) = 0.06 mag. This gives a high relative accuracy of extinction estimates even at highGalactic latitudes, where, according to our estimates, the median total Galactic extinction through theentire dust half-layer from the Sun to extragalactic objects is AV = 0.12 ± 0.06 mag. We have shown thatthe presented maps are among the best ones in data volume, space size, resolution, accuracy, and otherproperties.

JWST uncovers helium and water abundance variations in the bulge globular cluster NGC 6440

We used ultra-deep observations obtained with the NIRCam aboard the James Webb Space Telescope to explore the stellar population of NGC 6440: a typical massive, obscured, and contaminated globular cluster formed and orbiting within the Galactic bulge. Leveraging the exceptional capabilities of this camera, we sampled the cluster down to about five magnitudes below the main sequence turn-off in the (mF115W, mF115W − mF200W) colour–magnitude diagram. After carefully accounting for differential extinction and contamination by field interlopers, we find that the main sequence splits into two branches, each above and below the characteristic knee. By comparing the morphology of the colour–magnitude diagram with a suitable set of isochrones, we argue that the upper main sequence bi-modality is likely due to the presence of a He-enriched stellar population with a helium spread of ΔY = 0.04. The lower main sequence bi-modality can be attributed to variations in the abundance of water (i.e., oxygen) with Δ[O/Fe] ∼ −0.4. This is the first evidence of both helium and oxygen abundance variations in a globular cluster purely based on JWST observations. These results open the window for future in-depth investigations of the multiple population phenomenon in clusters located in the Galactic bulge, which were previously unfeasible with near-UV observations, due to prohibitive reddening and crowding conditions.

Asteroseismic age constraints on the open cluster NGC 2477 using oscillating stars identified with TESS FFI

Context. Asteroseismology is one of the few methods to derive ages of individual stars due to the high precision of their observations. Isochrone fitting is a powerful alternative method for deriving ages by studying clusters of stars. Pulsating stars in clusters should therefore allow for detailed studies of the stellar models. Aims. Our objectives are to exploit the NASA TESS data along with ESA Gaia data to search for and detect oscillations in cluster member stars. We analyse the intermediate-age open cluster NGC 2477, known to suffer from differential extinction, to explore if asteroseismology and cluster characteristics can help us understand the metallicity and extinction, as well as result in better age determinations than isochrone-fitting alone. Methods. We combined a multitude of recent observations from Gaia, high-resolution spectroscopy, and extinction maps to analyse the cluster and then search for and detect variability in the member stars using TESS full frame images (FFIs) data. To interpret all of these data, we used stellar structure, evolution and oscillation codes. Results. We conducted an in-depth analysis of the extinction and metallicity of NGC 2477, using the most recent spectroscopic, photometric, and extinction observations for the cluster. Analysis of dust and extinction maps confirmed that the differential extinction in the direction of the cluster is not due to the background. The cluster’s metallicity from high-resolution spectroscopy varies from 0.06 to 0.16 dex. We performed an isochrone fitting to the cluster using publically available isochrones (BASTI, MIST, and PARSEC), which provides a cluster age of between 0.6 to 1.1 Ga. Then using TESS FFI, we analysed the time dimension of the members of this cluster. We created optimised pixel light curves using the tessipack package which allows us to consider possible contamination by nearby stars. Using these light curves, we identified many interesting levels of variability of stars in this cluster, including binaries and oscillating stars. For the asteroseismic analysis, we selected a few uncontaminated A–F type oscillating stars and used the MESA and GYRE codes to interpret the frequency signals. By comparing the theoretical and the observed spectra, we identified frequency separations, Δν, for four stars. Then using the identified Δν and imposing that the best matched theoretical models have the same age, metallicity, and background extinction, we constrained the cluster’s age to 1.0 ± 0.1 Ga. Conclusions. We conclude that using the TESS FFI data, we can identify oscillating stars in clusters and constrain the age of the cluster using asteroseismology.

Periaqueductal gray matter and medial prefrontal cortex reflect negative prediction errors during differential conditioning.

Computational models of associative learning posit that negative prediction errors (PEs) arising from the omission of aversive outcomes weaken aversive Pavlovian associations during differential conditioning and extinction. It is possible that negative PEs may underlie exaggerated conditioned responses to the conditioned stimulus not paired with an aversitve outcome (CS-) during differential conditioning and to the conditioned stimulus originally paired with a aversive outcome (CS+) during extinction in patients with clinical anxiety disorders. Although previous research has demonstrated that manipulations of the periaqueductal gray matter (PAG) interfere with extinction learning in animals, the role of the PAG in processing negative PEs within the human brain is presently unclear. We set out to investigate how PAG responses and connectivity are impacted by negative PEs using ultra-high-field (7 T) functional magnetic resonance imaging and hierarchical Bayesian analysis. During differential conditioning, negative PEs were associated with larger responses within the lateral and dorsolateral PAG and increased connectivity between the dorsolateral PAG and medial areas of Brodmann area 9. Collectively, these results shed light on the association between activity within the PAG and medial prefrontal cortex and the omission of aversive outcomes during Pavlovian learning.

The PORTL Laboratory.

In the history of the field, behavior analysts have used the operant chamber as an apparatus for both teaching and experimental investigations. In the early days of the field, students spent significant time in the animal laboratory, using operant chambers to conduct hands-on experiments. These experiences allowed students to see behavior change as an orderly process and drew many students toward careers in behavior analysis. Today, most students no longer have access to animal laboratories. However, the Portable Operant Research and Teaching Lab (PORTL) can fill this void. PORTL is a table-top game that creates a free-operant environment for studying the principles of behavior and their application. This article will describe how PORTL works and the parallels between PORTL and the operant chamber. Examples will illustrate how PORTL can be used to teach concepts such as differential reinforcement, extinction, shaping, and other basic principles. In addition to its use as a teaching tool, PORTL provides a convenient and inexpensive way for students to replicate research studies and even conduct their own research projects. As students use PORTL to identify and manipulate variables, they gain a deeper understanding for how behavior works.

Revised Extinctions and Radii for 1.5 Million Stars Observed by APOGEE, GALAH, and RAVE

Asteroseismology has become widely accepted as a benchmark for accurate and precise fundamental stellar properties. It can therefore be used to validate and calibrate stellar parameters derived from other approaches. Meanwhile, one can leverage large-volume surveys in photometry, spectroscopy, and astrometry to infer stellar parameters over a wide range of evolutionary stages, independently of asteroseismology. Our pipeline, SEDEX (https://github.com/Jieyu126/SEDEX), compares the spectral energy distribution predicted by the MARCS and BOSZ model spectra with 32 photometric bandpasses, combining data from nine major, large-volume photometric surveys. We restrict the analysis to targets with available spectroscopy from the APOGEE, GALAH, and RAVE surveys to lift the temperature−extinction degeneracy. The cross-survey atmospheric parameter and uncertainty estimates are homogenized with artificial neural networks. Validation of our results with CHARA interferometry, Hubble Space Telescope CALSPEC spectrophotometry, and asteroseismology shows that we achieve high precision and accuracy. We present a catalog of improved interstellar extinction ( 0.14 mag) and stellar radii (σ R /R ≃ 7.4%) for ∼1.5 million stars in the low-to-high-extinction (A V ≲ 6 mag) fields observed by the spectroscopic surveys. We derive global extinctions for 184 Gaia DR2 open clusters and confirm the differential extinction in NGC 6791 and NGC 6819, which have been subject to extensive asteroseismic analysis. Furthermore, we report 36,854 double-lined spectroscopic main-sequence binary candidates. This catalog will be valuable for providing constraints on detailed modeling of stars and for constructing 3D dust maps of the Kepler field, the TESS Continuous Viewing Zones, and the PLATO long-duration observation fields.

Optical absorption and dichroism of single melanin nanoparticles.

Melanin nanoparticles (NPs) have important biological functions including photoprotection and colouration, and artificial melanin-like NPs are relevant for catalysis, drug delivery, diagnosis and therapy. Despite their importance, the optical properties of single melanin NPs have not been measured. We combine quantitative differential interference contrast (qDIC) and extinction microscopy to characterise the optical properties of single NPs, both naturally sourced from cuttlefish ink, as well as synthetic NPs using polydopamine (PDA) and L-3,4-dihydroxyphenylalanine (L-DOPA). Combining qDIC with extinction, we determine the absorption index of individual NPs. We find that on average the natural melanin NPs have a higher absorption index than the artificial melanin NPs. From the analysis of the polarisation-dependent NP extinction, the NP aspect ratio is determined, with mean values at 405 nm wavelength in agreement with transmission electron microscopy. At longer wavelengths, we observe an additional optical anisotropy which is attributed to dichroism by structural ordering of the melanin. Our quantitative analysis yields a dichroism of 2-10% of the absorption index, increasing with wavelength from 455 nm to 660 nm for L-DOPA and PDA. Such an in-depth quantification of the optical properties of single melanin NPs is important for the design and future application of these ubiquitous bionanomaterials.

Observational extinction reduces fear and its retention among adolescents and adults

Observational fear learning has been notably understudied in fear learning research, especially the potential benefits of observational extinction. Additionally, no studies have investigated observational extinction during adolescence, a key developmental stage for the emergence of anxiety disorders. This study compared observational and direct fear extinction following observational fear acquisition among adolescents and adults. Participants underwent differential observational fear acquisition. Next, participants underwent one of three fear extinctions: (1) observational extinction, (2) direct extinction, (3) no-extinction. Thereafter, participants underwent a US reminder and finally, a direct exposure test. Skin conductance response (SCR), self-reported fear, and risk assessment were measured. Differential observational fear acquisition was demonstrated by both age groups across all measures. During extinction, the observational and direct extinction groups did not differ in differential extinction, however, during the US reminder the observational group exhibited higher SCR compared to the direct group, but not the no-extinction group. Finally, during the direct exposure test, the no-extinction group showed greater differential risk assessment and higher SCR compared to the observational and direct groups. Additionally, adolescents showed poorer discrimination between the CSs compared to adults. Observational extinction successfully reduced fear and its retention amongst youth and adults pointing to the potential benefit of vicarious exposure therapy.

Fear learning and extinction predicts anxiety in daily life: a study of Pavlovian conditioning and ecological momentary assessment.

The association between anxious mood and aberrant fear learning mechanisms has not been fully elucidated. Studying how fear conditioning and extinction constructs relate to anxiety symptoms and reactivity to stressful and benign moments in everyday life provides a powerful addition to experimental paradigms. Fifty-one young adults completed laboratory-based differential conditioning and extinction tasks with (CS + ) and without (CS-) an aversive unconditional stimulus (US). Electrodermal skin conductance responses were measured during each phase, followed by ecological momentary assessment (EMA) tapping anxiety and stressors six times daily for seven days (2, 142 moments). Conditioned electrodermal reactivity to the CS + and overgeneralisation to the CS- were associated with greater change in anxiety (measured via EMA), across non-stressful situations, remaining the same across stressful situations. Likewise, during extinction when the CS + is now safe, more electrodermal reactivity to the CS + was associated with more anxiety change across non-stressful situations and remained the same across stressful situations. Also, during extinction when threat is absent, more electrodermal reactivity at the late stage of the CS- was associated with less momentary anxiety change in response to stressful situations; more electrodermal activity at the late stage of the CS + was associated with more anxiety change across non-stressful situations and remained the same across stressful situations. Sampling 'in vivo' emotion and stress experiences, study findings revealed links between conditioned electrodermal reactivity and overgeneralisation to safe stimuli and heightened anxious reactivity during non-stressful (i.e. safe) moments in daily life, coupled with less change in response to actual stressors.

Intolerance of uncertainty predicts altered threat expectancy ratings during reinstatement

Intolerance of uncertainty (IU) is a transdiagnostic risk factor for psychiatric disorders, and plays an important role in fear and threat learning under uncertainty. The ‘reinstatement of fear/threat’ is an understudied phenomenon thought to represent clinical symptom relapse. Reinstatement of conditioned responding can be captured in the laboratory by presenting unsignaled presentations of an aversive unconditional stimulus. The present study investigated IU as a predictor of reinstatement effects, such that individuals higher in IU, relative to lower IU, would show larger reinstatement. Sixty-two participants completed the Intolerance of Uncertainty Scale and provided threat expectancy ratings (i.e. certainty of receiving a shock) during a differential threat conditioning and extinction paradigm with reinstatement. Findings suggested a differential increase in threat expectancy ratings to both the threat and safety cue following reinstatement, although this effect was small and did not survive follow-up tests. Nevertheless, IU was a significant predictor of reinstatement to the threat cue but not the safety cue, although this effect was not in the expected direction. Specifically, higher IU was associated with reduced threat expectancy ratings post-reinstatement. These findings provide support for the limited literature demonstrating an important role for IU in reinstatement effects and should be investigated further.

The musca molecular cloud: The perfect ‘filament’ is still a sheet

ABSTRACT The true three-dimensional (3D) morphology of the Musca molecular cloud is a topic that has received significant attention lately. Given that Musca does not exhibit intense star-formation activity, unveiling its shape has the potential to also reveal crucial information regarding the physics that dictates the formation of the first generation of stars within molecular clouds. Here, we revisit the shape of Musca and we present a comprehensive array of evidence pointing towards a shape that is extended along the line-of-sight dimension: (a) 3D maps of differential extinction; (b) new non-local thermodynamic equilibrium radiative transfer simulations of CO rotational transitions from a sheet-like, magnetically dominated simulated cloud; (c) an effective/critical density analysis of available CO observations; and (d) indirect consequences that a filamentary structure would have had, from a theoretical star-formation perspective. We conclude that the full collection of observational evidence strongly suggests that Musca has a sheet-like geometry.

Phylogenomics and biogeography of Torreya (Taxaceae)—Integrating data from three organelle genomes, morphology, and fossils and a practical method for reducing missing data from RAD‐seq

AbstractRestriction site‐associated DNA sequencing (RAD‐seq) enables obtaining thousands of genetic markers for phylogenomic studies. However, RAD‐seq data are subject to allele dropout (ADO) due to polymorphisms at enzyme cutting sites. We developed a new pipeline, RAD‐seq Allele Dropout Remedy in our study of the gymnosperm genus, Torreya, to mitigate ADO in outgroups by recovering missing loci from previously published transcriptomes. By using RADADOR to supplement Rad‐seq data in combination with plastome and mitochondrial gene sequences, morphology, and fossil records, we reconstructed the phylogenetic and biogeographic histories of the genus and tested hypotheses on anomalies of biodiversity of the eastern Asian‐North American floristic disjunction. Our results showed that our pipeline recovered many loci missing from the outgroup, and the improved data yielded a more robust phylogeny for Torreya. Using the fossilized birth–death model and divergence–extinction–cladogenesis method, we resolved a detailed biogeographic history of Torreya that suggested a Jurassic origin spanning Laurasia and differential speciation and extinction among continents accounting for modern diversity, which is biased toward eastern Asia (EA). The biogeographic results also supported a vicariance origin of modern Torreya from a widespread ancestor in EA and North America (NA) in the mid‐Eocene, and cross Beringian exchange in the early Paleogene before the vicariant isolation, in contrast to the “out of NA” pattern common to gymnosperms and to the “out of EA” hypothesis previously proposed for the genus. Furthermore, we observed phylogenetic discordance between the nuclear and plastid phylogenies for Torreya jackii, suggesting differential lineage sorting of plastid genomes among species of Torreya or plastid genome capture in T. jackii.