Vibrational relaxation of diatomic molecules at high temperatures

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Interplay between Human Microbiota and Celiac Disease

Celiac disease is an autoimmune disorder of the small intestine in which gluten, an energy-storage protein in wheat and other cereals, elicits an immune response leading to villous atrophy. Despite a strong genetic component, the disease arises sporadically over the lifetime leading us to hypothesize the microbiome might be a trigger. Here, we re-examined 16S data from 3 prior studies examining celiac disease and the microbiome with newer computational tools: the dada2 and PICRUSt 2 pipelines. Our results both confirmed findings of previous studies and generated new data regarding the celiac microbiome of India and Mexico. The datasets were also pooled to determine whether any taxonomic or metabolic features remained consistent across the world using a variety of data transformations to control for batch effects. Our results showed the celiac microbiome displays dysbiosis without a discernable pattern, likely indicating that perturbations in the CD microbiome are a result of the disease rather than a cause of the disease. Data from PICRUSt 2 further confirms this, showing connections to the CD metabolome which are supported by previous research examining dysbiotic microbiomes

Maine’s Technology Sectors and Clusters: Status and Strategy

The concept of “clusters” has been a key idea in economic development in Maine and other states for more than a decade. In 2002, the Maine Science & Technology Foundation (MSTF) released a study of the cluster characteristics of the seven technology sectors that were designated as the focus of attention for Maine’s research and development support programs. This study is a step towards implementing the Brookings Institution’s recommendations for an aggressive effort to build and expand clusters. It updates and expands the 2002 MSTF cluster report and also builds upon the work of Porter and others to identify distinctive specializations in Maine’s economy by focusing in much greater detail on the knowledge, skills, networks, and entrepreneurial activities in Maine that make up clusters

Electron-Impact Ionization of Laser-Aligned Atoms -- Contributions from Both Natural and Unnatural-Parity States

Synopsis. The progress of experimental and theoretical measurements for (e,2e) ionization cross sections from laser-aligned atoms is presented here. It is found that both natural and unnatural parity contributions must be included in the models to emulate the experimental data

Four-Body Model for Transfer Excitation

We present here a four-body model for transfer-excitation collisions, which we call the four-body transfer-excitation (4BTE) model. Each two-body interaction is explicitly included in the 4BTE model, allowing us to study the effects of individual two-body interactions. We apply our model to fully differential cross sections for proton+helium collisions, and study the effect of the incident projectile-atom interaction, the scattered projectile-ion interaction, the projectile-nuclear interaction, and electron correlation within the target atom

Compact acceleration of energetic neutral atoms using high intensity laser-solid interaction

Recent advances in high-intensity laser-produced plasmas have demonstrated their potential as compact charge particle accelerators. Unlike conventional accelerators, transient quasi-static charge separation acceleration fields in laser produced plasmas are highly localized and orders of magnitude larger. Manipulating these ion accelerators, to convert the fast ions to neutral atoms with little change in momentum, transform these to a bright source of MeV atoms. The emittance of the neutral atom beam would be similar to that expected for an ion beam. Since intense laser-produced plasmas have been demonstrated to produce high-brightness-low-emittance beams, it is possible to envisage generation of high-flux, low-emittance, high energy neutral atom beams in length scales of less than a millimeter. Here, we show a scheme where more than 80% of the fast ions are reduced to energetic neutral atoms and demonstrate the feasibility of a high energy neutral atom accelerator that could significantly impact applications in neutral atom lithography and diagnostics

Low Energy (e,2e) Coincidence Studies of NH₃: Results from Experiment and Theory

Experimental and theoretical triple differential cross sections (TDCS) from ammonia are presented in the low energy regime with outgoing electron energies from 20 eV down to 1.5 eV. Ionization measurements from the 3a1, 1e1, and 2a1 molecular orbitals were taken in a coplanar geometry. Data from the 3a1 and 1e1 orbitals were also obtained in a perpendicular plane geometry. The data are compared to predictions from the distorted wave Born approximation and molecular-three-body distorted wave models. The cross sections for the 3a1 and 1e1 orbitals that have p-like character were found to be similar, and were different to that of the 2a1 orbital which has s-like character. These observations are not reproduced by theory, which predicts the structure of the TDCS for all orbitals should be similar. Comparisons are also made to results from experiment and theory for the iso-electronic targets neon and methane

Electron-impact-ionization cross sections of H₂ for low outgoing electron energies from 1 to 10 eV

Theoretical and experimental fully differential cross sections are presented for electron-impact ionization of molecular hydrogen in a plane perpendicular to the incident beam direction. The experimental data exhibit a maximum for 1-eV electrons detected 180° apart and a minimum for 10-eV electrons. We investigate the different physical effects which cause back-to-back scattering and demonstrate that, over the energy range from 10 to 1 eV, a direct transition is observed from a region where Wannier threshold physics is essentially unimportant to where it completely dominates

Comparison of experimental and theoretical electron-impact-ionization triple-differential cross sections for ethane

We have recently examined electron-impact ionization of molecules that have one large atom at the center, surrounded by H nuclei (H2O, NH3, CH4). All of these molecules have ten electrons; however, they vary in their molecular symmetry. We found that the triple-differential cross sections (TDCSs) for the highest occupied molecular orbitals (HOMOs) were similar, as was the character of the HOMO orbitals which had a p-type “peanut” shape. In this work, we examine ethane (C2H6) which is a molecule that has two large atoms surrounded by H nuclei, so that its HOMO has a double-peanut shape. The experiment was performed using a coplanar symmetric geometry (equal final-state energies and angles). We find the TDCS for ethane is similar to the single-center molecules at higher energies, and is similar to a diatomic molecule at lower energies