The Effects of Reference Frames on 3D Menus in Virtual Environments

The emergence of affordable Head Mounted Displays (HMD) means Virtual Reality (VR) systems are now available to wider audiences. Other than the key target audience, gamers, groups as diverse as oil and gas industries, medical, military, entertainment and education have created demand for effective Virtual Environments (VE). To be effective certain VEs need to properly convey textual information. This is done using 3D menus. It is very important these menus are displayed in an ergonomic manner and do not obstruct important content. The study collected measures of user experience, comfort and memory recall. The study found that reference frames for 3D menus presenting textual information do not influence user experience or memory recall. However, there was a significant difference in user behavior between the reference frames, which has implications for repeated stress injury

Graphene-based photovoltaic cells for near-field thermal energy conversion

Thermophotovoltaic devices are energy-conversion systems generating an electric current from the thermal photons radiated by a hot body. In far field, the efficiency of these systems is limited by the thermodynamic Schockley-Queisser limit corresponding to the case where the source is a black body. On the other hand, in near field, the heat flux which can be transferred to a photovoltaic cell can be several orders of magnitude larger because of the contribution of evanescent photons. This is particularly true when the source supports surface polaritons. Unfortunately, in the infrared where these systems operate, the mismatch between the surface-mode frequency and the semiconductor gap reduces drastically the potential of this technology. Here we show that graphene-based hybrid photovoltaic cells can significantly enhance the generated power paving the way to a promising technology for an intensive production of electricity from waste heat.Comment: 5 pages, 4 figure

The Effects of Neonicotinoid Exposure on Embryonic Development and Organ Mass in Northern Bobwhite Quail

Since their emergence in the early 1990s, neonicotinoid use has increased exponentially to make them the world's most prevalent insecticides. Although there is considerable research concerning the lethality of neonicotinoids, their sub-lethal and developmental effects are still being explored, especially with regards to non-mammalian species. The goal of this research was to investigate the effects of the neonicotinoid imidacloprid on the morphological and physiological development of northern bobwhite quail (Colinus virginianus). Bobwhite eggs (n = 650) were injected with imidacloprid concentrations of 0 (sham), 10, 50, 100 and 150 grams per kilogram of egg mass, which was administered at day 0 (pre-incubation), 3, 6, 9, or 12 of growth. Embryos were dissected on day 19 when they were weighed, staged, and examined for any overt structural deformities. Embryonic heart, liver, lungs and kidneys were also weighed and preserved for future use. Treated embryos exhibited increased frequency of severely deformed beaks and legs, as well as larger hearts and smaller lungs at the higher dosing concentrations. Some impacts are more pronounced in specific dosing periods, implying that there may be critical windows of development when embryos are highly susceptible to neonicotinoid exposure. This investigation suggests that imidacloprid could play a significant role in chick survival and declining quail populations in treated regions of the country

Resonance Raman studies of cyclic and linear polyenes

Thesis (M.S.)--Michigan State University. Department of Chemistry, 1979Includes bibliographical references (page 37

A case study: examining perspectives of membership and staff to identify leadership, beef industry, and organization issues within the American Simmental Association

The purpose of the study was to explore the needs of the American Simmental Association as an organization to determine how leadership is defined, identify industry and ASA issues, and assess perspectives on the future of the organization and beef industry. Data were collected and compared, through interviews and field notes, from a representation on membership (21) and staff (7) to examine leadership, ASA, and the beef industry. Through In-Vivo coding, 2001 initial codes (staff: 493 and membership: 1508) were presented. The researcher conducted an intrinsic case study (Stake, 1995). Codes were then merged through pattern and axial coding. Key findings indicated that the similarities between membership and staff were division, lack of or need for communication and education, ASA science and education, and solutions to division. Differences between the participant groups were membership themes: right people in right positions, leadership addressing issues, and keep delivering the message and staff themes: confidence in decisions, risking our own obsolescence, and cull the herd. The study provided insight and recommendations for American Simmental Association's future research and practices

The Effects of Reference Frames on 3D Menus in Virtual Environments

The emergence of affordable Head Mounted Displays (HMD) means Virtual Reality (VR) systems are now available to wider audiences. Other than the key target audience, gamers, groups as diverse as oil and gas industries, medical, military, entertainment and education have created demand for effective Virtual Environments (VE). To be effective certain VEs need to properly convey textual information. This is done using 3D menus. It is very important these menus are displayed in an ergonomic manner and do not obstruct important content. The study collected measures of user experience, comfort and memory recall. The study found that reference frames for 3D menus presenting textual information do not influence user experience or memory recall. However, there was a significant difference in user behavior between the reference frames, which has implications for repeated stress injury

Angle resolved photoemission spectroscopy of Sr_2CuO_2Cl_2 - a revisit

We have investigated the lowest binding-energy electronic structure of the model cuprate Sr_2CuO_2Cl_2 using angle resolved photoemission spectroscopy (ARPES). Our data from about 80 cleavages of Sr_2CuO_2Cl_2 single crystals give a comprehensive, self-consistent picture of the nature of the first electron-removal state in this model undoped CuO_2-plane cuprate. Firstly, we show a strong dependence on the polarization of the excitation light which is understandable in the context of the matrix element governing the photoemission process, which gives a state with the symmetry of a Zhang-Rice singlet. Secondly, the strong, oscillatory dependence of the intensity of the Zhang-Rice singlet on the exciting photon-energy is shown to be consistent with interference effects connected with the periodicity of the crystal structure in the crystallographic c-direction. Thirdly, we measured the dispersion of the first electron-removal states along G->(pi,pi) and G->(pi,0), the latter being controversial in the literature, and have shown that the data are best fitted using an extended t-J-model, and extract the relevant model parameters. An analysis of the spectral weight of the first ionization states for different excitation energies within the approach used by Leung et al. (Phys. Rev. B56, 6320 (1997)) results in a strongly photon-energy dependent ratio between the coherent and incoherent spectral weight. The possible reasons for this observation and its physical implications are discussed.Comment: 10 pages, 8 figure

ARPES: A probe of electronic correlations

Angle-resolved photoemission spectroscopy (ARPES) is one of the most direct methods of studying the electronic structure of solids. By measuring the kinetic energy and angular distribution of the electrons photoemitted from a sample illuminated with sufficiently high-energy radiation, one can gain information on both the energy and momentum of the electrons propagating inside a material. This is of vital importance in elucidating the connection between electronic, magnetic, and chemical structure of solids, in particular for those complex systems which cannot be appropriately described within the independent-particle picture. Among the various classes of complex systems, of great interest are the transition metal oxides, which have been at the center stage in condensed matter physics for the last four decades. Following a general introduction to the topic, we will lay the theoretical basis needed to understand the pivotal role of ARPES in the study of such systems. After a brief overview on the state-of-the-art capabilities of the technique, we will review some of the most interesting and relevant case studies of the novel physics revealed by ARPES in 3d-, 4d- and 5d-based oxides.Comment: Chapter to appear in "Strongly Correlated Systems: Experimental Techniques", edited by A. Avella and F. Mancini, Springer Series in Solid-State Sciences (2013). A high-resolution version can be found at: http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/Reviews/ARPES_Springer.pdf. arXiv admin note: text overlap with arXiv:cond-mat/0307085, arXiv:cond-mat/020850