Kasha’s Rule and Koopmans’ Correlations for Electron Tunnelling through Repulsive Coulomb Barriers in a Polyanion

The long-range electronic structure of polyanions is defined by the repulsive Coulomb barrier (RCB). Excited states can decay by resonant electron tunnelling through RCBs, but such decay has not been observed for electronically excited states other than the first excited state, suggesting a Kasha-type rule for resonant electron tunnelling. Using action spectroscopy, photoelectron imaging, and computational chemistry, we show that the fluorescein dianion, Fl2–, partially decays through electron tunnelling from the S2 excited state, thus demonstrating anti-Kasha behavior, and that resonant electron tunnelling adheres to Koopmans’ correlations, thus disentangling different channels

Photoelectron spectroscopy of the deprotonated tryptophan anion: the contribution of deprotomers to its photodetachment channels †

Photoelectron spectroscopy and electronic structure calculations are used to investigate the electronic structure of the deprotonated anionic form of the aromatic amino acid tryptophan, and its chromophore, indole. The photoelectron spectra of tryptophan, recorded at different wavelengths across the UV, consist of two direct detachment channels and thermionic emission, whereas the hν = 4.66 eV spectrum of indole consists of two direct detachment features. Electronic structure calculations indicate that two deprotomers of tryptophan are present in the ion beam; deprotonation of the carboxylic acid group (Trp(i)−) or the N atom on the indole ring (Trp(ii)−). Strong similarities are observed between the direct detachment channels in the photoelectron spectra of tryptophan and indole, which in conjunction with electronic structure calculations, indicate that electron loss from Trp(ii)− dominates this portion of the spectra. However, there is some evidence that direct detachment of Trp(i)− is also observed. Thermionic emission is determined to predominantly arise from the decarboxylation of Trp(i)−, mediated by the ππ* excited state near λ = 300 nm, which results in an anionic fragment with a negative electron affinity that readily autodetaches

Modified dipole-dipole interaction and dissipation in an atomic ensemble near surfaces

We study how the radiative properties of a dense ensemble of atoms can be modified when they are placed near or between metallic or dielectric surfaces. If the average separation between the atoms is comparable or smaller than the wavelength of the scattered photons, the coupling to the radiation field induces long-range coherent interactions based on the interatomic exchange of virtual photons. Moreover, the incoherent scattering of photons back to the electromagnetic field is known to be a many-body process, characterized by the appearance of superradiant and subradiant emission modes. By changing the radiation field properties, in this case by considering a layered medium where the atoms are near metallic or dielectric surfaces, these scattering properties can be dramatically modified. We perform a detailed study of these effects, with focus on experimentally relevant parameter regimes. We finish with a specific application in the context of quantum information storage,where the presence of a nearby surface is shown to increase the storage time of an atomic excitation that is transported across a one-dimensional chain

Colon capsule endoscopy investigation based on faecal haemoglobin concentration in symptomatic patients to detect bowel disease

We would like to thank the biochemistry laboratory staff at Raigmore and Ninewells Hospital for processing and analysing FIT samples, and all the patients who participated in the ScotCap evaluation.Peer reviewe

Stable microbial community composition on the Greenland Ice Sheet

The first molecular-based studies of microbes in snow and on glaciers have only recently been performed on the vast Greenland Ice Sheet (GrIS). Aeolian microbial seeding is hypothesized to impact on glacier surface community compositions. Localized melting of glacier debris (cryoconite) into the surface ice forms cryoconite holes, which are considered ‘hot spots’ for microbial activity on glaciers. To date, few studies have attempted to assess the origin and evolution of cryoconite and cryoconite hole communities throughout a melt season. In this study, a range of experimental approaches was used for the first time to study the inputs, temporal and structural transformations of GrIS microbial communities over the course of a whole ablation season. Small amounts of aeolian (wind and snow) microbes were potentially seeding the stable communities that were already present on the glacier (composed mainly of Proteobacteria, Cyanobacteria and Actinobacteria). However, the dominant bacterial taxa in the aeolian samples (Firmicutes) did not establish themselves in local glacier surface communities. Cryoconite and cryoconite hole community composition remained stable throughout the ablation season following the fast community turnover, which accompanied the initial snow melt. The presence of stable communities in cryoconite and cryoconite holes on the GrIS will allow future studies to assess glacier surface microbial diversity at individual study sites from sampling intervals of short duration only. Aeolian inputs also had significantly different organic δ13C values (-28.0 to -27.0‰) from the glacier surface values (-25.7 to -23.6‰), indicating that in situ microbial processes are important in fixing new organic matter and transforming aeolian organic carbon. The continuous productivity of stable communities over one melt season makes them important contributors to biogeochemical nutrient cycling on glaciers

Evidence for a Kernel of Truth in Children’s Facial Impressions of Children’s Niceness, but not Shyness

Acknowledgements: We are grateful to the parents and children who helped make this research possible. We would like to thank Romina Palermo for providing us the opportunity to contact her sample of participants and to use some existing data. We also thank Lou Ewing for sharing the Zeb the Alien Scientist testing materials, and Saba Siddique for comments regarding a manuscript draft. Finally, we would like to thank Kaitlyn Turbett, Dielle Horne, Saba Siddique, Chloe Giffard, and Maira Vicente Braga, for help testing participants. JC, LJ, GR, and CS conceived the study and helped to draft and edit the manuscript. JC programmed the experiment, collected most participant data, performed the statistical analyses and drafted the first manuscript draft. EB coordinated image collection and testing schedules. All authors participated in the study design, and read, provided critical revisions and approved the final manuscript. The study methods, hypotheses and analyses were pre-registered(https://osf.io/kjtva/registrations). Funding: This research was supported by an APR Internship Academic Mentor Grant to CS, an Australian Research Council (ARC) Centre of Excellence Grant award to GR [CE110001021], ARC Discovery Early Career Research Award to CS [DE190101043], ARC Discovery Grant to GR and CS [DP170104602], ARC Discovery Grant to LJ [140101743], and a Research Training Program stipend to JC.Peer reviewedPostprin

Blood Vessels Under the Microscope

This paper looks at blood vessels. All humans and animals have blood vessels, including your pet rabbit or dog, a whale or a giraffe! We need blood vessels to stay alive. This paper answers many questions, including what blood vessels are used for and why we need them. It looks at how and why blood vessels grow and what they look like. It also explores what happens when things go wrong with blood vessels and if blood vessels are ever bad for us. So, if you want to know how many miles of blood vessels there are in your body, learn about problems astronauts have in space, see real blood vessels through a microscope, or learn how to keep your blood vessels healthy, you are reading the right article