On Flux Rope Stability and Atmospheric Stratification in Models of Coronal Mass Ejections Triggered by Flux Emergence

Flux emergence is widely recognized to play an important role in the initiation of coronal mass ejections. The Chen-Shibata (2000) model, which addresses the connection between emerging flux and flux rope eruptions, can be implemented numerically to study how emerging flux through the photosphere can impact the eruption of a pre-existing coronal flux rope. The model's sensitivity to the initial conditions and reconnection micro-physics is investigated with a parameter study. In particular, we aim to understand the stability of the coronal flux rope in the context of X-point collapse and the effects of boundary driving in both unstratified and stratified atmospheres. In the absence of driving, we assess the behavior of waves in the vicinity of the X-point. With boundary driving applied, we study the effects of reconnection micro-physics and atmospheric stratification on the eruption. We find that the Chen-Shibata equilibrium can be unstable to an X-point collapse even in the absence of driving due to wave accumulation at the X-point. However, the equilibrium can be stabilized by reducing the compressibility of the plasma, which allows small-amplitude waves to pass through the X-point without accumulation. Simulations with the photospheric boundary driving evaluate the impact of reconnection micro-physics and atmospheric stratification on the resulting dynamics: we show the evolution of the system to be determined primarily by the structure of the global magnetic fields with little sensitivity to the micro-physics of magnetic reconnection; and in a stratified atmosphere, we identify a novel mechanism for producing quasi-periodic behavior at the reconnection site behind a rising flux rope as a possible explanation of similar phenomena observed in solar and stellar flares.Comment: Submitted Feb 28, 2014 to, accepted Aug 14, 2014 by Astronomy & Astrophysics. 13 pages, 10 figures, 2 table

Investigation of the wear resistance of high chromium white irons

High chromium white irons are commonly used throughout the mineral processing industry to handle erosive and erosivecorrosive slurries. These alloys are used in critical wear areas in the form of castings, or deposited as weld overlays onto steel substrates. The wear resistance of these alloys is due to their microstructure, which comprises hard rod like carbides dispersed in a matrix of austenite or martensite. The microstructure and carbide morphologies of these alloys can vary significantly depending on the chemical composition and the production process. This investigation uses a simple slurry pot test apparatus with slurries containing a mixed proportion of quartz particles to produce a mixed mode of impact and low angle erosion. A variety of different commercially produced castings and weld overlays ranging from low carbide volume fraction hypoeutectic alloys to hypereutectic alloys having a high carbide volume fraction were tested. The wear mechanism and hence the wear resistance of the alloys tested has been related to the matrix and the carbide morphologies.G.D. Nelson, G.L.F. Powell and V.M. Linto

Localised States of Fabry-Perot Type in Graphene Nano-Ribbons

This book collects some new progresses on research of graphene from theoretical and experimental aspects in a variety of topics, such as graphene nanoribbons, graphene quantum dots, and graphene-based resistive switching memory. The authors of each chapter give a unique insight about the specific intense research area of graphene. This book is suitable for graduate students and researchers with background in physics, chemistry, and materials as reference

High School Biology in the Age of the Next Generation Science Standards: A Student-Centered Approach

The article describes a biology teacher’s approach to inquiry-based instruction grounded in a sociocultural learning perspective.  The course designed by the Biology Teacher includes references to the literature and epistemic practice-based routines and procedures.  The urban students in this study integrate the practices to design an investigation to solve a problem with soil quality.  Specific details describe the epistemic practices enacted by the students and their responses to the learning experience.  The study illustrates how the Biology Teacher used the students’ culture, experiences and knowledge to promote meaningful science practice related to the lives of the students.  The study was conducted in an urban environment; however, approaches are conducive to science instruction in all NGSS classrooms

Shuttle sensors

Requirements, quantities, location, and temperature environment limitations of sensors for space shuttle

Superconductivity in a Mesoscopic Double Square Loop: Effect of Imperfections

We have generalized the network approach to include the effects of short-range imperfections in order to analyze recent experiments on mesoscopic superconducting double loops. The presence of weakly scattering imperfections causes gaps in the phase boundary $B(T)$ or $\Phi(T)$ for certain intervals of $T$, which depend on the magnetic flux penetrating each loop. This is accompanied by a critical temperature $T_c(\Phi)$, showing a smooth transition between symmetric and antisymmetric states. When the scattering strength of imperfections increases beyond a certain limit, gaps in the phase boundary $T_c(B)$ or $T_c(\Phi)$ appear for values of magnetic flux lying in intervals around half-integer $\Phi_0=hc/2e$. The critical temperature corresponding to these values of magnetic flux is determined mainly by imperfections in the central branch. The calculated phase boundary is in good agreement with experiment.Comment: 9 pages, 6 figure

Tuning into the Future: Informal Learning and Music Education

When adolescents are engaged in learning, research has shown a decrease in alcohol and drug use, higher retention rates and fewer failures throughout high school, lower rates of depression as well as lower rates of anti-social and criminal behaviours. Attention to student engagement with a priority on 21st century learning skills requires the examination of various pedagogies, including using informal learning practices as the foundation for instruction with adolescents in schools. This pilot project targets Grade 7 to 10 students in two school settings where adolescent engagement is a priority; it examines the viability of implementing informal learning practices within the Canadian context