Safety learning in anxiety, Pavlovian conditioned inhibition and Covid concerns

Experimental studies of fear conditioning have identified the effectiveness of safety signals in inhibiting fear and maintaining fear-motivated behaviours. In fear conditioning procedures, the presence of safety signals means that the otherwise expected feared outcome will not now occur. Differences in the inhibitory learning processes needed to learn safety are being identified in various psychological and psychiatric conditions. However, despite early theoretical interest, the role of conditioned inhibitors as safety signals in anxiety has been under-investigated to date, in part because of the stringent test procedures required to confirm the demonstration of conditioned inhibition as such. Nonetheless, the theoretical implications of an inhibitory learning perspective continue to influence clinical practice. Moreover, our understanding of safety signals is of additional importance in the context of the increased health anxiety and safety behaviours generated by the Covid-19 pandemic.

Disgusting Democrats and Repulsive Republicans: Members of Political Outgroups Are Considered Physically Gross

The status of disgust as a sociomoral emotion is debated. We conducted a stringent test of whether social stimuli (specifically, political outgroup members) can elicit physical disgust, as distinct from moral or metaphorical disgust. We employed stimuli (male faces) matched on baseline disgustingness, provided other ways for participants to express negativity toward outgroup members, and used concrete self-report measures of disgust, as well as a nonverbal measure (participants’ facial expressions). Across three preregistered studies (total N = 915), we found that political outgroup members are judged to be “disgusting,” although this effect is generally weaker for concrete self-report measures and absent for the nonverbal measure. This suggests that social stimuli are capable of eliciting genuine physical disgust, although it is not always outwardly expressed, and the strength of this result depends on the measures employed. We discuss implications of these results for research on sociomoral emotions and American politics.

A Stringent Test of Magnetic Models of Stellar Evolution

Main-sequence stars with convective envelopes often appear larger and cooler than predicted by standard models of stellar evolution for their measured masses. This is believed to be caused by stellar activity. In a recent study, accurate measurements were published for the K-type components of the 1.62-day detached eclipsing binary EPIC 219511354, showing the radii and temperatures for both stars to be affected by these discrepancies. This is a rare example of a system in which the age and chemical composition are known, by virtue of being a member of the well-studied open cluster Ruprecht 147 (age~3 Gyr, [Fe/H] = +0.10). Here, we report a detailed study of this system with nonstandard models incorporating magnetic inhibition of convection. We show that these calculations are able to reproduce the observations largely within their uncertainties, providing robust estimates of the strength of the magnetic fields on both stars: 1600 ± 130 G and 1830 ± 150 G for the primary and secondary, respectively. Empirical estimates of the magnetic field strengths based on the measured X-ray luminosity of the system are roughly consistent with these predictions, supporting this mechanism as a possible explanation for the radius and temperature discrepancies.

Self-assembly of photonic crystals by controlling the nucleation and growth of DNA-coated colloids

DNA-coated colloids can self-assemble into an incredible diversity of crystal structures, but their applications have been limited by poor understanding and control over the crystallization dynamics. To address this challenge, we use microfluidics to quantify the kinetics of DNA-programmed self-assembly along the entire crystallization pathway, from thermally activated nucleation through reaction-limited and diffusion-limited phases of crystal growth. Our detailed measurements of the temperature and concentration dependence of the kinetics at all stages of crystallization provide a stringent test of classical theories of nucleation and growth. After accounting for the finite rolling and sliding rates of micrometer-sized DNA-coated colloids, we show that modified versions of these classical theories predict the absolute nucleation and growth rates with quantitative accuracy. We conclude by applying our model to design and demonstrate protocols for assembling large single crystals with pronounced structural coloration, an essential step in creating next-generation optical metamaterials from colloids.

Lamb-dip cavity ring-down spectroscopy of acetylene at 1.4 μm

Doppler-free saturated-absorption Lamb dips are observed for weak vibration-rotation transitions of C2H2 between 7167 and 7217 cm−1, using a frequencycomb assisted cavity ring-down spectrometer based on the use of a pair of phase-locked diode lasers. We measured the absolute center frequency of sixteen lines belonging to the 2ν3 + ν15 band, targeting ortho and para states of the molecule. Line pairs of the P and Q branches were selected so as to form a “V”-scheme, sharing the lower energy level. Such a choice made it possible to determine the rotational energy separations of the excited vibrational state for J-values from 11 to 20. Line-center frequencies are determined with an overall uncertainty between 2 and 13 kHz. This is over three order of magnitude more accurate than previous experimental studies in the spectral region around the wavelength of 1.4 μm. The retrieved energy separations provide a stringent test of the so-called MARVEL method recently applied to acetylene.

CWENO Finite-Volume Interface Capturing Schemes for Multicomponent Flows Using Unstructured Meshes

In this paper we extend the application of unstructured high-order finite-volume central-weighted essentially non-oscillatory (CWENO) schemes to multicomponent flows using the interface capturing paradigm. The developed method achieves high-order accurate solution in smooth regions, while providing oscillation free solutions at discontinuous regions. The schemes are inherently compact in the sense that the central stencils employed are as compact as possible, and that the directional stencils are reduced in size, therefore simplifying their implementation. Several parameters that influence the performance of the schemes are investigated, such as reconstruction variables and their reconstruction order. The performance of the schemes is assessed under a series of stringent test problems consisting of various combinations of gases and liquids, and compared against analytical solutions, computational and experimental results available in the literature. The results obtained demonstrate the robustness of the new schemes for several applications, as well as their limitations within the present interface-capturing implementation.

PermaPhosSer: autonomous synthesis of functional, permanently phosphorylated proteins

Installing stable, functional mimics of phosphorylated amino acids into proteins offers a powerful strategy to study protein regulation. Previously, a genetic code expansion (GCE) system was developed to translationally install non-hydrolyzable phosphoserine (nhpSer), with the γ-oxygen replaced with carbon, but it has seen limited usage. Here, we achieve a 40-fold improvement in this system by engineering into Escherichia coli a biosynthetic pathway that produces nhpSer from the central metabolite phosphoenolpyruvate. Using this "PermaPhosSer" system — an autonomous 21-amino acid E. coli expression system for incorporating nhpSer into target proteins — we show that nhpSer faithfully mimics the effects of phosphoserine in three stringent test cases: promoting 14-3-3/client complexation, disrupting 14-3-3 dimers, and activating GSK3-β phosphorylation of the SARS-CoV-2 nucleocapsid protein. This facile access to nhpSer containing proteins should allow nhpSer to replace Asp and Glu as the go-to pSer phosphomimetic for proteins produced in E. coli.

On measurement of photon polarization in radiative penguin B decays to baryons

A measurement of the photon polarization in radiative penguin B decays provides a test of the Standard Model and a probe for New Physics, that can lead to a deviation from the Standard Model prediction of left-handed photons in $$b\rightarrow s \gamma $$ b → s γ . We propose a new method to measure the photon polarization using the baryonic decay $$B^- \rightarrow \Lambda \bar{p} \gamma $$ B - → Λ p ¯ γ . The P-violating $$\Lambda $$ Λ -hyperon decay allows a measurement of the $$\Lambda $$ Λ helicity to be performed, which can be uniquely related to the photon polarization in a model-independent way. The $$B^- \rightarrow \Lambda \bar{p} \gamma $$ B - → Λ p ¯ γ decay was recently measured to have a large branching fraction providing a possibility to get meaningful results with the data already available at LHC and B-factory experiments. An increase of the B-meson sample at high luminosity LHC experiments and Belle II should provide a really stringent test by using this method already in the near future.