25,619 research outputs found
Discovery of a possible symbiotic binary in the Large Magellanic Cloud
We report the discovery of a possible symbiotic star, in the Large Magellanic
Cloud (LMC). The object under consideration here, designated as RP 870, was
detected during the course of a comprehensive H survey of the LMC by
Reid & Parker (2012). The spectrum of RP 870 showed high ionization emission
lines of He I, He II and [O III] and molecular absorption bands of TiO
6180, 7100. The collective signatures of a hot component
(high excitation/ionization lines) and of a cool component (TiO molecular
bands) are seen in RP 870, from which we propose it as a symbiotic star. Since
known symbiotic systems are rare in the LMC, possibly less than a dozen are
known, we thought the present detection to be interesting enough to be
reported.Comment: 3 pages, 2 figures, accepted for publication in Research Notes of the
AA
Methodology for urban rail and construction technology research and development planning
A series of transit system visits, organized by the American Public Transit Association (APTA), was conducted in which the system operators identified the most pressing development needs. These varied by property and were reformulated into a series of potential projects. To assist in the evaluation, a data base useful for estimating the present capital and operating costs of various transit system elements was generated from published data. An evaluation model was developed which considered the rate of deployment of the research and development project, potential benefits, development time and cost. An outline of an evaluation methodology that considered benefits other than capital and operating cost savings was also presented. During the course of the study, five candidate projects were selected for detailed investigation; (1) air comfort systems; (2) solid state auxiliary power conditioners; (3) door systems; (4) escalators; and (5) fare collection systems. Application of the evaluation model to these five examples showed the usefulness of modeling deployment rates and indicated a need to increase the scope of the model to quantitatively consider reliability impacts
Bostonia. Volume 1
Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs
Origin of spontaneous electric dipoles in homonuclear niobium clusters
Surprisingly large spontaneous electric dipole moments recently observed in
homonuclear niobium clusters below 100 K (Moro el. al. Science 300, 1265
(2003)) are explained using first-principles electronic structure calculations.
The calculated moments for Nb(n) (n <= 15) closely follow the experimental data
in which large dipole moments are seen for n = 11-14. We establish that the
dipoles are strongly correlated with the geometrical asymmetry of the clusters.
The magnitude of the dipole moment is roughly proportional to the spread in the
principal moments of inertia and its direction tends to align along the axis of
the largest principal moment. Charge deformation densities reveal directional,
partially covalent bonds that enhance the formation of asymmetric geometries.
Classical simulations of the deflection of a cluster in a molecular beam reveal
that the electronic dipole may persist at higher temperatures, but is masked by
the rotational dynamics of the cluster
Investigation of Noise Field and Velocity Profiles of an Afterburning Engine
Sound pressure levels, frequency spectrum, and jet velocity profiles are presented for an engine-afterburner combination at various values of afterburner fuel - air ratio. At the high fuel-air ratios, severe low-frequency resonance was encountered which represented more than half the total energy in the sound spectrum. At similar thrust conditions, lower sound pressure levels were obtained from a current fighter air craft with a different afterburner configuration. The lower sound pressure levels are attributed to resonance-free afterburner operation and thereby indicate the importance of acoustic considerations in afterburner design
The cognitive organization of music knowledge: a clinical analysis
Despite much recent interest in the clinical neuroscience of music processing, the cognitive organization of music as a domain of non-verbal knowledge has been little studied. Here we addressed this issue systematically in two expert musicians with clinical diagnoses of semantic dementia and Alzheimer’s disease, in comparison with a control group of healthy expert musicians. In a series of neuropsychological experiments, we investigated associative knowledge of musical compositions (musical objects), musical emotions, musical instruments (musical sources) and music notation (musical symbols). These aspects of music knowledge were assessed in relation to musical perceptual abilities and extra-musical neuropsychological functions. The patient with semantic dementia showed relatively preserved recognition of musical compositions and musical symbols despite severely impaired recognition of musical emotions and musical instruments from sound. In contrast, the patient with Alzheimer’s disease showed impaired recognition of compositions, with somewhat better recognition of composer and musical era, and impaired comprehension of musical symbols, but normal recognition of musical emotions and musical instruments from sound. The findings suggest that music knowledge is fractionated, and superordinate musical knowledge is relatively more robust than knowledge of particular music. We propose that music constitutes a distinct domain of non-verbal knowledge but shares certain cognitive organizational features with other brain knowledge systems. Within the domain of music knowledge, dissociable cognitive mechanisms process knowledge derived from physical sources and the knowledge of abstract musical entities
Test results of the Chrysler upgraded automotive gas turbine engine: Initial design
The upgraded engine as built to the original design was deficient in power and had excessive specific fuel consumption. A high instrumented version of the engine was tested to identify the sources of the engine problems. Analysis of the data shows the major problems to be low compressor and power turbine efficiency and excessive interstage duct losses. In addition, high HC and CO emission were measured at idle, and high NOx emissions at high energy speeds
FINDCHIRP: an algorithm for detection of gravitational waves from inspiraling compact binaries
Matched-filter searches for gravitational waves from coalescing compact
binaries by the LIGO Scientific Collaboration use the FINDCHIRP algorithm: an
implementation of the optimal filter with innovations to account for unknown
signal parameters and to improve performance on detector data that has
nonstationary and non-Gaussian artifacts. We provide details on the FINDCHIRP
algorithm as used in the search for subsolar mass binaries, binary neutron
stars, neutron star-black hole binaries, and binary black holes.Comment: 19 pages, 1 figure, journal version with Creative Commons 4.0
open-access license adde
Early Childhood Special Education in a Refugee Resettlement Community: Challenges and Innovative Practices
There has been a significant increase in the number of children who are culturally and linguistically diverse (CLD) who qualify for early childhood special education (ECSE) services (Banerjee & Guiberson, 2012). The current study investigates the challenges and innovative practices in the evaluation and (ECSE) services for preschool aged children who are refugees. Twenty-eight early childhood educators who work in a small refugee resettlement community participated in a qualitative study using semi-structured interviews resulting in themes regarding challenges and innovative practices. Challenges include: lack of validated assessments, wait time for evaluations, different cultural perspectives and family advocacy. Innovative practices include: assessing skills not dependent on language and including caregivers in evaluations. Implications for future research and teacher preparation are discussed
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