Branching ratio measurements of the 7.12-MeV state in 16O

Knowledge of the gamma-ray branching ratios of the 7.12-MeV state of 16O is important for the extrapolation of the 12C(a,g)16O cross section to astrophysical energies. Ground state transitions provide most of the 12C(a,g)16O total cross section while cascade transitions have contributions of the order of 10-20%. Determining the 7.12-MeV branching ratio will result in a better extrapolation of the cascade and E2 ground state cross section to low energies. We report here on measurements on the branching ratio of the 7.12-MeV level in 16O.Comment: 4 pages, 5 figures. Contribution to the Eigth International Symposium on Nuclei in the Cosmo

Angular distributions of γ rays from the 7Li(p,γ) reaction at low energies

Angular distributions of the 14–17 MeV γ rays from the 7Li(p,γ) reaction at Ep=450, 402, and 80 keV were measured at 0°≤θlab≤135°, using a BGO detector and a 28-μg/cm2 LiF target. The angular distributions at Ep=450 and 402 keV agree with the previous results by Mainsbridge; at Ep=80 keV the ground-state transition is anisotropic on the order of 20%, confirming recent results by Chasteler et al

The structure of borders in a small world

Geographic borders are not only essential for the effective functioning of government, the distribution of administrative responsibilities and the allocation of public resources, they also influence the interregional flow of information, cross-border trade operations, the diffusion of innovation and technology, and the spatial spread of infectious diseases. However, as growing interactions and mobility across long distances, cultural, and political borders continue to amplify the small world effect and effectively decrease the relative importance of local interactions, it is difficult to assess the location and structure of effective borders that may play the most significant role in mobility-driven processes. The paradigm of spatially coherent communities may no longer be a plausible one, and it is unclear what structures emerge from the interplay of interactions and activities across spatial scales. Here we analyse a multi-scale proxy network for human mobility that incorporates travel across a few to a few thousand kilometres. We determine an effective system of geographically continuous borders implicitly encoded in multi-scale mobility patterns. We find that effective large scale boundaries define spatially coherent subdivisions and only partially coincide with administrative borders. We find that spatial coherence is partially lost if only long range traffic is taken into account and show that prevalent models for multi-scale mobility networks cannot account for the observed patterns. These results will allow for new types of quantitative, comparative analyses of multi-scale interaction networks in general and may provide insight into a multitude of spatiotemporal phenomena generated by human activity.Comment: 9 page

Atomistic mechanisms for the ordered growth of Co nano-dots on Au(788): comparison of VT-STM experiments and multi-scaled calculations

Hetero-epitaxial growth on a strain-relief vicinal patterned substrate has revealed unprecedented 2D long range ordered growth of uniform cobalt nanostructures. The morphology of a Co sub-monolayer deposit on a Au(111) reconstructed vicinal surface is analyzed by Variable Temperature Scanning Tunneling Microscopy (VT-STM) experiments. A rectangular array of nano-dots (3.8 nm x 7.2 nm) is found for a particularly large deposit temperature range lying from 60 K to 300 K. Although the nanodot lattice is stable at room temperature, this paper focus on the early stage of ordered nucleation and growth at temperatures between 35 K and 480 K. The atomistic mechanisms leading to the nanodots array are elucidated by comparing statistical analysis of VT-STM images with multi-scaled numerical calculations combining both Molecular Dynamics for the quantitative determination of the activation energies for the atomic motion and the Kinetic Monte Carlo method for the simulations of the mesoscopic time and scale evolution of the Co submonolayer

Total cross section for p-d breakup below 30 MeV

The total cross section for p-d breakup is studied in terms of the elastic S-matrix through the unitary condition. Calculations using the complex Kohn variational method along with the Pair Correlated Hyperspherical Harmonic basis are presented. The results have been restricted to energies below Ep=30 MeV where Coulomb effects are expected to be sizable and are compared to the existing data. Two different measurements have been found in the literature: 40 years ago, Gibbons and Macklin (1959); and 26 years ago, Carlosn et al. (1973). The calculations are found to be in reasonable agreement with these old data, though a discrepancy is observed near the deuteron breakup threshold. Moreover, a detailed analysis of the contributions to the observable from different partial waves has been presented. Unexpectedly, the main contribution for a wide range of energies has been detected in the J=3/2- state

Process tomography of field damping and measurement of Fock state lifetimes by quantum non-demolition photon counting in a cavity

The relaxation of a quantum field stored in a high-$Q$ superconducting cavity is monitored by non-resonant Rydberg atoms. The field, subjected to repetitive quantum non-demolition (QND) photon counting, undergoes jumps between photon number states. We select ensembles of field realizations evolving from a given Fock state and reconstruct the subsequent evolution of their photon number distributions. We realize in this way a tomography of the photon number relaxation process yielding all the jump rates between Fock states. The damping rates of the $n$ photon states ($0\leq n \leq 7$) are found to increase linearly with $n$. The results are in excellent agreement with theory including a small thermal contribution

Nitrogen in the environment: nitrification

Pdf created from MU Extension webpage, July 2022."Many organisms live in the soil. Some of these are able to change ammonium nitrogen (NH4+) to nitrate nitrogen (NO3-). This process is called nitrification. Nitrification has two steps -- both are carried out by bacteria that live in the soil (Figure 1). Common sources of ammonium in the soil result from decaying plants and organic matter, or ammonium can come from the application of manure or nitrogen fertilizers."--Page 1.Reviewed by David Brune (Department of Agricultural Engineering), Scott C. Killpack and Daryl Buchholz (Department of Agronomy

The Three-Nucleon System Near the N-d Threshold

The three-nucleon system is studied at energies a few hundred keV above the N-d threshold. Measurements of the tensor analyzing powers $T_{20}$ and $T_{21}$ for p-d elastic scattering at $E_{c.m.}=432$ keV are presented together with the corresponding theoretical predictions. The calculations are extended to very low energies since they are useful for extracting the p-d scattering lengths from the experimental data. The interaction considered here is the Argonne V18 potential plus the Urbana three-nucleon potential. The calculation of the asymptotic D- to S-state ratio for $^3$H and $^3$He, for which recent experimental results are available, is also presented.Comment: Latex, 11 pages, 2 figures, to be published in Phy.Lett.

Nitrogen in the environment: essential plant nutrients

Pdf created from MU Extension webpage, July 2022."Carbon, oxygen and hydrogen are among the most basic elements necessary for plant growth. Plants obtain these elements from water and carbon dioxide in the air and soil. Plants also require additional 'mineral elements' that they obtain from the soil for proper growth and development. These mineral elements, together with carbon, hydrogen and oxygen, are referred to as essential plant elements or nutrients. They are essential because they are important to plant functions. Plants would not be able to grow, develop and reproduce without them. Although all are not necessarily essential to all plants, all are essential to some."--Page 1.Reviewed by David Brune (Department of Agricultural Engineering), Scott C. Killpack and Daryl Buchholz (Department of Agronomy