Elevated central serotonin levels inhibit emotional crying

Previous research has suggested a possible role of serotonin in emotional expressions, such as crying. We have found that a transient increase of central serotonin levels by means of oral administration of paroxetine reduces crying in response to emotional movies in healthy female volunteers. This is the first direct evidence of an important role of serotonin in this uniquely human emotional response

Para-ortho Hydrogen Conversion; Solving A 90-year Old Mystery

It is well known among spectroscopists that hydrogen has two modifications: para-H$_2$ and ortho-H$_2$. Pure para-H$_2$ can be produced by leading ``normal'' H$_2$, a 3:1 ortho:para mixture, over a catalyst at low temperature. It is perhaps less well known that para-ortho H$_2$ conversion is also catalyzed by collisions with paramagnetic molecules, such as O$_2$. Almost ninety years ago Farkas and Sachsse measured the rate coefficient of para-ortho H$_2$ conversion in gas mixtures with O$_2$.[1] In the same year, 1933, it was proposed by Wigner [2] that it is the magnetic dipole-dipole coupling between the electron spin of O$_2$ and the nuclear spins of the two protons in H$_2$ that is responsible for the conversion. In asymmetric collisions this coupling makes the two H-nuclei inequivalent and mixes the nuclear spin functions of para- and ortho-H$_2$, as well as their rotational states with even and odd $j$ values. Another mechanism, suggested to be much more effective, was proposed later: the exchange interaction with the open-shell O$_2$ induces spin density into the electronic wavefunction of H$_2$. In most collisions the spin density is different at the two H-nuclei, which makes them inequivalent by different hyperfine interactions through the Fermi contact term. An important application of para-H$_2$ is in NMR spectroscopy and its imaging variant, MRI. By adding para-H$_2$ to the sample the sensitivity of NMR can be increased by four orders of magnitude by a phenomenon called para-hydrogen induced polarization (PHIP). Para-ortho H$_2$ conversion by O$_2$ in the gas phase was remeasured in 2014 in view of this application. A detailed and quantitative understanding of the conversion process was still lacking, however. We theoretically investigated the para-ortho H$_2$ conversion by collisions with O$_2$ in a first principles approach.[3] Both mechanisms were taken into account and the corresponding coupling terms were quantitatively evaluated as functions of the geometry of the O$_2$-H$_2$ collision complex by means of \textit{ab initio} electronic structure calculations. Then they were included in nearly exact quantum mechanical coupled-channels scattering calculations for the collisions between O$_2$ and H$_2$, which yielded the para-ortho H$_2$ conversion cross sections and the rate coefficients for temperatures up to 400\,K. The conversion rate and its temperature dependence are in good agreement with the values measured in H$_2$-O$_2$ gas mixtures. The calculations provide detailed insight into the conversion process. [1] L. Farkas and H. Sachsse, Z. Phys. Chem. B {\bf 23}, 1 (1933). [2] E. Wigner, Z. Phys. Chem. B {\bf 23}, 28 (1933). [3] X. Zhang, T. Karman, G.~C. Groenenboom, and A. van der Avoird, Nat. Sci. (2021); https://doi.org/10.1002/ntls.10002

An Interactive Tablecloth for Facilitating Discussion in a Culturally Diverse Group

Group discussions are a useful tool in a number of environments: from working towards a common goal in a business setting, to gathering feedback on an exhibit in a museum for example. One issue in such sessions is that some group members can talk more loudly and confidently than others, making some group members change their mind or keep quiet, this can result in interesting differences of opinion being lost. In this paper we present a tool for facilitating such group discussions. The tool is an interactive tablecloth that is controlled with tangible interfaces, and provides a method for each group member’s voice to be heard prior to discussion, thus preserving the diversity of responses. When tested after an immersive theatre performance, the tool effectively allowed each group member to answer questions individually prior to beginning group discussion. This also allowed the facilitator to effectively coordinate the discussion in an efficient manner

Intrinsic fluctuations in random lasers

We present a quantitative experimental and theoretical study of shot-to-shot intensity fluctuations in the emitted light of a random laser. A model that clarifies these intrinsic fluctuations is developed. We describe the output versus input power graphs of the random laser with an effective spontaneous emission factor (beta factor).Comment: accepted by Phys. Rev. A. submitted; 7 pages, 5 figure

Spatial Extent of Random Laser Modes

We have experimentally studied the distribution of the spatial extent of modes and the crossover from essentially single-mode to distinctly multimode behavior inside a porous gallium phosphide random laser. This system serves as a paragon for random lasers due to its exemplary high index contrast. In the multimode regime, we observed mode competition. We have measured the distribution of spectral mode spacings in our emission spectra and found level repulsion that is well described by the Gaussian orthogonal ensemble of random-matrix theory

Characterization of methanol as a magnetic field tracer in star-forming regions

Magnetic fields play an important role during star formation. Direct magnetic field strength observations have proven specifically challenging in the extremely dynamic protostellar phase. Because of their occurrence in the densest parts of star forming regions, masers, through polarization observations, are the main source of magnetic field strength and morphology measurements around protostars. Of all maser species, methanol is one of the strongest and most abundant tracers of gas around high-mass protostellar disks and in outflows. However, as experimental determination of the magnetic characteristics of methanol has remained largely unsuccessful, a robust magnetic field strength analysis of these regions could hitherto not be performed. Here we report a quantitative theoretical model of the magnetic properties of methanol, including the complicated hyperfine structure that results from its internal rotation. We show that the large range in values of the Land\'{e} g-factors of the hyperfine components of each maser line lead to conclusions which differ substantially from the current interpretation based on a single effective g-factor. These conclusions are more consistent with other observations and confirm the presence of dynamically important magnetic fields around protostars. Additionally, our calculations show that (non-linear) Zeeman effects must be taken into account to further enhance the accuracy of cosmological electron-to-proton mass ratio determinations using methanol.Comment: 23 pages, 3 figures, excluding Supplementary information. Author manuscript version before editorial/copyediting by Nature Astronomy. Journal version available via http://rdcu.be/FPeB . Supplementary material available via https://static-content.springer.com/esm/art%3A10.1038%2Fs41550-017-0341-8/MediaObjects/41550_2017_341_MOESM1_ESM.pd