Immersive virtual reality and education: a study into the effectiveness of using this technology with preservice teachers.

Immersive virtual reality (IVR) is a rapidly advancing technology utilized across varying education fields for learning and educational applications. IVR provides the capabilities of computer simulations and embodied cognition experiences through a hands-on activity, making it a natural step to improve learning. Creating educational applications in IVR for use with students and preservice teachers could be a laborious and costly endeavor and require teacher belief in its effectiveness, so research is essential to investigate whether these applications are useful in advancing prekindergarten through Grade 12 (P-12) student learning. Research in this field is new, limited, and practically void of its use in P-12 learning environments. This inquiry expanded upon the literature on IVR technology in education and preservice teacher use of technology. Specifically, the purpose of this study was to investigate the impact of IVR technology on preservice teachers through an experience focused on the American Civil Rights Movement, specifically on knowledge attainment, lesson planning effectiveness, and motivation for future use in their instructional practice. Participants were 21 elementary preservice teachers in a diverse metropolitan university. Results indicated participants in the IVR group significantly increased scores on a content test, reported engagement with the experience, and indicated likelihood to use IVR with their future students

Head-Tail Clouds: Drops to Probe the Diffuse Galactic Halo

A head-tail high-velocity cloud (HVC) is a neutral hydrogen halo cloud that appears to be interacting with the diffuse halo medium as evident by its compressed head trailed by a relatively diffuse tail. This paper presents a sample of 116 head-tail HVCs across the southern sky (d < 2 deg) from the HI Parkes All Sky Survey (HIPASS) HVC catalog, which has a spatial resolution of 15.5 arcmin (45 pc at 10 kpc) and a sensitivity of N_HI=2 x 10^(18) cm^(-2) (5 sigma). 35% of the HIPASS compact and semi-compact HVCs (CHVCs and :HVCs) can be classified as head-tail clouds from their morphology. The clouds have typical masses of 730 M_sun at 10 kpc (26,000 M_sun at 60 kpc) and the majority can be associated with larger HVC complexes given their spatial and kinematic proximity. This proximity, together with their similar properties to CHVCs and :HVCs without head-tail structure, indicate the head-tail clouds have short lifetimes, consistent with simulation predictions. Approximately half of the head-tail clouds can be associated with the Magellanic System, with the majority in the region of the Leading Arm with position angles pointing in the general direction of the movement of the Magellanic System. The abundance in the Leading Arm region is consistent with this feature being closer to the Galactic disk than the Magellanic Stream and moving through a denser halo medium. The head-tail clouds will feed the multi-phase halo medium rather than the Galactic disk directly and provide additional evidence for a diffuse Galactic halo medium extending to at least the distance of the Magellanic Clouds.Comment: MNRAS Accepted, 10 figures, 7 in colo

Stability of Localized Wave Fronts in Bistable Systems

Localized wave fronts are a fundamental feature of biological systems from cell biology to ecology. Here, we study a broad class of bistable models subject to self-activation, degradation, and spatially inhomogeneous activating agents. We determine the conditions under which wave-front localization is possible and analyze the stability thereof with respect to extrinsic perturbations and internal noise. It is found that stability is enhanced upon regulating a positional signal and, surprisingly, also for a low degree of binding cooperativity. We further show a contrasting impact of self-activation to the stability of these two sources of destabilization. DOI: 10.1103/PhysRevLett.110.03810

Are Compact High-Velocity Clouds Extragalactic Objects?

Compact high-velocity clouds (CHVCs) are the most distant of the HVCs in the Local Group model and would have HI volume densities of order 0.0003/cm^3. Clouds with these volume densities and the observed neutral hydrogen column densities will be largely ionized, even if exposed only to the extragalactic ionizing radiation field. Here we examine the implications of this process for models of CHVCs. We have modeled the ionization structure of spherical clouds (with and without dark matter halos) for a large range of densities and sizes, appropriate to CHVCs over the range of suggested distances, exposed to the extragalactic ionizing photon flux. Constant-density cloud models in which the CHVCs are at Local Group distances have total (ionized plus neutral) gas masses roughly 20-30 times larger than the neutral gas masses, implying that the gas mass alone of the observed population of CHVCs is about 40 billion solar masses. With a realistic (10:1) dark matter to gas mass ratio, the total mass in such CHVCs is a significant fraction of the dynamical mass of the Local Group, and their line widths would exceed the observed FWHM. Models with dark matter halos fare even more poorly; they must lie within approximately 200 kpc of the Galaxy. We show that exponential neutral hydrogen column density profiles are a natural consequence of an external source of ionizing photons, and argue that these profiles cannot be used to derive model-independent distances to the CHVCs. These results argue strongly that the CHVCs are not cosmological objects, and are instead associated with the Galactic halo.Comment: 30 pages, 14 figures; to appear in The Astrophysical Journa