Strongly nonlinear convection in binary fluids: Minimal model for extended states using symmetry decomposed modes

Spatially extended stationary and traveling states in the strongly nonlinear regime of convection in layers of binary fluid mixtures heated from below are described by a few-mode-model. It is derived from the proper hydrodynamic balance equations including experimentally relevant boundary conditions with a non-standard Galerkin approximation that uses numerically obtained, symmetry decomposed modes. Properties of the model are elucidated and compared with full numerical solutions of the field equations.Comment: 16 pages, including 5 postscript figure

Analysis of microwave radiometric measurements from Skylab

There are no author-identified significant results in this report

Adolescent Attitudes Toward and Perceptions of Suicide, Stigma, and Help-Seeking Behavior

Suicide is a leading cause of death for adolescents and represents a major national health concern (American Foundation for Suicide Prevention, [AFSP], 2015; (Centers for Disease Control [CDC], 2013). Because adolescents spend the majority of their day at school (Erbacher, Singer, & Poland, 2015), the effectiveness of school-based suicide prevention programs may be improved through better understanding of adolescents’ views on the subject of suicide and the factors that may influence participation in prevention efforts. The present study explored the attitudes and perceptions of seventh grade students from a suburban middle school in Pennsylvania, using archival survey data. Variables that were examined included attitudes toward suicide, real or perceived stigma toward suicide, suicide literacy, and attitudes toward help-seeking for suicidal thoughts and behaviors. Results indicated that an overwhelming majority of participants believe that suicide can be prevented and that intervention is necessary; however, adolescents still hold some degree of stigmatizing attitudes toward suicide and are uncertain about how to identify and assist those at risk. There were few significant differences between the perceptions and attitudes of males and females on this topic. The results confirm the need for school-based suicide prevention education, with specific focus on identification of warning signs and on ways to intervene when concerns for self or a peer arises. More importantly, the results emphasize the need to implement schoolbased suicide prevention education programs much earlier than what is considered typical. Limitations to the study and directions for future research are also discussed

Genetic Optimization and Simulation of a Piezoelectric Pipe-Crawling Inspection Robot

Using the DarwinZk development software, a genetic algorithm (GA) was used to design and optimize a pipe-crawling robot for parameters such as mass, power consumption, and joint extension to further the research of the Miniature Inspection Systems Technology (MIST) team. In an attempt to improve on existing designs, a new robot was developed, the piezo robot. The final proposed design uses piezoelectric expansion actuators to move the robot with a 'chimneying' method employed by mountain climbers and greatly improves on previous designs in load bearing ability, pipe traversing specifications, and field usability. This research shows the advantages of GA assisted design in the field of robotics

The Effects of Technology-Based Conducting Practice on Skill Achievement in Novice Conductors

The purpose of this study was to compare technology-based practice (Radio Baton and Digital Conducting System) to self-practice (recorded music) on the skill achievement of beginning conductors. Participants (N = 33) were undergraduate music majors—education and performance—from two beginning conducting classes randomly assigned to either the technology-based group or the self-practice group. Subjects worked for three, 15-minute sessions on the following skills: staccato conducting, legato conducting, and steadiness of tempo. The experimental design was a pretest-posttest using two conducting etudes to measure six dependent variables: staccato conducting, staccato presence, staccato steadiness of tempo, legato conducting, legato presence, and legato steadiness of tempo. Three expert judges scored videotaped pre and posttests with interjudge reliability ranging from .77 to .84. Six Analyses of Covariance tests (ANCOVA) were used to analyze the aforementioned dependent variables. A significant difference resulted between treatment and control groups for only the legato conducting variable (p = .05). The researchers concluded that a longer treatment period was perhaps necessary to produce a significant difference between the groups on the other variables

Interface Between Titanium Miniplate/Screw and Human Calvaria

This study demonstrates interfacial changes of titanium miniplate/screw with normal calvaria and nonvascularized calvarial bone graft ensued from craniectomy in a 53-year-old female. In 18 months after operation, a right parietal bone containing an L-shaped miniplate with screws, 5mm long and 2mm in external diameter, was harvested, fixed, and embedded in methylmetacrylate. Fifteen micrometer thick sections were made by an EXAKT cutting-grinding system (Exakt Company, Hamburg, Germany), and reviewed under the bright field light microscope. The mean of the bonecontacting surface ratio (BCSR) in six screwed bone was 64.1%; 69.3% in normal bone, and 60.4% in grafted bone. The trabecular bone areas in 10x5mm (50mm2) rectangular area of diploe surrounding the screws was 43.02mm2; 45.25mm2 in normal calvaria; and 41.82mm2 in grafted bone. The mean Ca/P peak-height ratio of the plated and screwed calvaria was 1.47 in a 9mm wide zone around each screw; 1.37 in normal calvaria; and 1.51 in grafted calvaria. We concede that the effect of direct contact of titanium with screws onto the bone is as much as an osseous integration (osseointegration)

Influence of the Soret effect on convection of binary fluids

Convection in horizontal layers of binary fluids heated from below and in particular the influence of the Soret effect on the bifurcation properties of extended stationary and traveling patterns that occur for negative Soret coupling is investigated theoretically. The fixed points corresponding to these two convection structures are determined for realistic boundary conditions with a many mode Galerkin scheme for temperature and concentration and an accurate one mode truncation of the velocity field. This solution procedure yields the stable and unstable solutions for all stationary and traveling patterns so that complete phase diagrams for the different convection types in typical binary liquid mixtures can easily be computed. Also the transition from weakly to strongly nonlinear states can be analyzed in detail. An investigation of the concentration current and of the relevance of its constituents shows the way for a simplification of the mode representation of temperature and concentration field as well as for an analytically manageable few mode description.Comment: 30 pages, 12 figure

High-quality highly strained InGaAs quantum wells grown on InP using (InAs)n(GaAs)0.25 fractional monolayer superlattices

International audience(InAs) n /(GaAs) m n1.5-2, m0.25 monolayer fractional monolayer superlattices FMS have been used to grow highly strained InGaAs quantum wells QWs on InP by molecular beam epitaxy. We show that FMS quantum wells have better structural and optoelectronic properties compared to equivalent QWs grown using standard procedures. In addition, the onsets of the three-dimensional growth mode and plastic relaxation are delayed, which allows the highest emission wavelength in the In x Ga 1x As/InGaAlAs/InP system to be extended up to 2.35 m at high growth temperatures 500 °C