Virtual geographic environments in socio-environmental modeling: a fancy distraction or a key to communication?

Modeling and simulation are recognized as effective tools for management and decision support across various disciplines; however, poor communication of results to the end users is a major obstacle for properly using and understanding model output. Visualizations can play an essential role in making modeling results accessible for management and decision-making. Virtual reality (VR) and virtual geographic environments (VGEs) are popular and potentially very rewarding ways to visualize socio-environmental models. However, there is a fundamental conflict between abstraction and realism: models are goal-driven, and created to simplify reality and to focus on certain crucial aspects of the system; VR, in the meanwhile, by definition, attempts to replicate reality as closely as possible. This elevated realism may add to the complexity curse in modeling, and the message might be diluted by too many (background) details. This is also connected to information overload and cognitive load. Moreover, modeling is always associated with the treatment of uncertainty–something difficult to present in VR. In this paper, we examine the use of VR and, specifically, VGEs in socio-environmental modeling, and discuss how VGEs and simulation modeling can be married in a mutually beneficial way that makes VGEs more effective for users, while enhancing simulation models

Determination of the electromagnetic character of soft dipole modes solely based on quasicontinuous gamma spectroscopy

We show that the combined analysis of the quasicontinuous gamma spectra from the (He-3,alpha) and the (n-thermal,2gamma) reactions gives the possibility to measure the electromagnetic character of soft dipole resonances. Two-step gamma-cascade spectra have been calculated, using level densities and radiative strength functions from the (He-3,alpha gamma) reaction. The calculations show that the intensity of the two-step cascades depends on the electromagnetic character of the soft dipole resonance under study. The difference reaches 40-100% which can be measured experimentally.Comment: 9 pages including 1 table and 2 figure

Test of nuclear level density inputs for Hauser-Feshbach model calculations

The energy spectra of neutrons, protons, and alpha-particles have been measured from the d+59Co and 3He+58Fe reactions leading to the same compound nucleus, 61$Ni. The experimental cross sections have been compared to Hauser-Feshbach model calculations using different input level density models. None of them have been found to agree with experiment. It manifests the serious problem with available level density parameterizations especially those based on neutron resonance spacings and density of discrete levels. New level densities and corresponding Fermi-gas parameters have been obtained for reaction product nuclei such as 60Ni,60Co, and 57Fe

Enhanced radiative strength in the quasi-continuum of 117Sn

Radiative strength functions of 117Sn has been measured below the neutron separation energy using the (3He,3He'gamma) reactions. An increase in the slope of the strength functions around E_gamma= 4.5 MeV indicates the onset of a resonance-like structure, giving a significant enhancement of the radiative strength function compared to standard models in the energy region 4.5 <= E_gamma <= 8.0 MeV. For the first time, the functional form of this resonance-like structure has been measured in an odd tin nucleus below neutron threshold in the quasi-continuum region.Comment: 4 pages, 3 figure