2,548 research outputs found

    The Radio Emission from the Ultra-Luminous Far-Infrared Galaxy NGC 6240

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    We present new radio observations of the ``prototypical'' ultra-luminous far- infrared galaxy NGC~6240, obtained using the VLA at 20~cm in `B' configuration and at 3.6~cm in `A' configuration. These data, along with those from four previous VLA observations, are used to perform a comprehensive study of the radio emission from NGC~6240. Approximately 70\% (~3 x 1023^{23} W~Hz−1^{-1}) of the total radio power at 20 cm originates from the nuclear region ( <~ 1.5 kpc), of which half is emitted by two unresolved (R< 36pc)coresandhalfbyadiffusecomponent.Theradiospectrumofthenuclearemissionisrelativelyflat(R <~ 36 pc) cores and half by a diffuse component. The radio spectrum of the nuclear emission is relatively flat (\alpha= 0.6; =~ 0.6; S_{\nu} \propto \nu^{-\alpha}). The supernova rate required to power the diffuse component is consistent with that predicted by the stellar evolution models of Rieke \etal (1985). If the radio emission from the two compact cores is powered by supernova remnants, then either the remnants overlap and form hot bubbles in the cores, or they are very young ( <~ 100 yr). Nearly all of the other 30\% of the total radio power comes from an ``arm-like'' region extending westward from the nuclear region. The western arm emission has a steep spectrum (\alpha= 1.0),suggestiveofagingeffectsfromsynchrotronorinverse−Comptonlosses,andisnotcorrelatedwithstarlight;wesuggestthatitissynchrotronemissionfromashellofmaterialdrivenbyagalacticsuperwind.Inverse−Comptonscatteringoffar−infraredphotonsintheradiosourcesisexpectedtoproduceanX−rayfluxof 2−6x10 =~ 1.0), suggestive of aging effects from synchrotron or inverse-Compton losses, and is not correlated with starlight; we suggest that it is synchrotron emission from a shell of material driven by a galactic superwind. Inverse-Compton scattering of far-infrared photons in the radio sources is expected to produce an X-ray flux of ~2-6 x 10^{-14}$ erg/s/cm2 in the 2-10 keV band. No significant radio emission is detected from or near the possible ultra-massive ``dark core'' hypothesized by Bland-Hawthorn, Wilson \& Tully (1991).Comment: 36 pages (text and tables) as an uuencoded compressed postscript file (figures available upon request), accepted for the ApJ (20 Nov issue), STScI preprint no. ?? -- May 199

    Developing A Culturally Responsive Classroom Collaborative Of Faculty, Students, And Institution

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    Culture is integral to the learning process. It is the organization and way of life within the community of students and teachers and directs the way they communicate, interact, and approach teaching and learning. Although founded in particular values and principles, the academy, like most organizations, is impacted day-to-day by its culture. Yet, the traditional higher education institution has not been designed to operate within a racially or ethnically diverse student population. The social, political, economic, and cultural forces that support the institution influence the teaching and learning environments. To better address cultural diversity in the classroom, faculty must first examine their own cultural background and understand how biases may affect their interactions with students. To advance teaching and learning in the college classroom requires an understanding of the underlying values, beliefs, perceptions and assumptions of students, which affect their understanding of what they hear and read as well as how they express themselves in the classroom. When teachers recognize these different qualities, classroom instruction can be designed to connect content to students’ backgrounds. This paper examines one approach to building a teaching and learning community through faculty professional development and collaboration. It provides an overview of a 5-part workshop series conducted for faculty at the Johnson & Wales University Providence campus on intercultural learning and culturally responsive teaching. Focusing on the essential components of personalizing culture through the five institutions of family, school, religion, politics, and economics through workshop activities, it is an investigation of individual and institutional backgrounds to determine how faculty may recognize the forces that influence student behavior, and how to engage them in a more active learning process

    F.A.C.E.S. (Faculty Academic Community Education Showcase): Professional Growth Experiences In A Career University

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    Institutes of higher education exist for the purpose of developing, fostering, nurturing, and stimulating the intellectual growth and development of students. The core values of a college education provide students conceptual and practical educational opportunities that focus on improving their skills and knowledge. These skills and knowledge translate into purposeful, real-life learning experiences. However, in the academic community, learning is not restricted to students. Faculty, too, must be supported and provided opportunities for personal and professional growth and development.  Although professional development is not a novel concept in the education profession, schools often take up the gauntlet, but fall short of running with it. A commitment to share the collective skills, teaching strategies, and experiences of colleagues in the university community should be one of the institution’s core values. The need today for academic rigor and the emphasis on accountability and evidence of professional development of teachers have become key components in faculty performance evaluations in both teaching and research higher educational institutional settings.   This paper examines how a career university addresses professional development by embracing change in its faculty orientation process at the start of the academic year through the implementation of a faculty development program and sustainable model for building a teaching and learning showcase of faculty talent. The orientation program - F.A.C.E.S. (Faculty Academic Community Education Showcase) - provides a series of interactive seminars conducted by and for full-time faculty at the Johnson &amp; Wales University (JWU) Providence, Rhode Island, campus that mirrors their professional expertise, educational best practices, and career experiences within and beyond the JWU academic community. It examines the program goals and objectives, evidence of its evaluation by participants and administration, and the follow-up programs in place to provide further opportunities throughout the academic year that meet faculty needs to learn and engage in a learning environment that translates into and enhances the learning experiences of their students

    Developing A Culturally Responsive Classroom Collaborative Of Faculty, Students, And Institution

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    Culture is integral to the learning process.&nbsp; It is the organization and way of life within the community of students and teachers and directs the way they communicate, interact, and approach teaching and learning. Although founded in particular values and principles, the academy, like most organizations, is impacted day-to-day by its culture. Yet, the traditional higher education institution has not been designed to operate within a racially or ethnically diverse student population. The social, political, economic, and cultural forces that support the institution influence the teaching and learning environments. To better address cultural diversity in the classroom, faculty must first examine their own cultural background and understand how biases may affect their interactions with students. To advance teaching and learning in the college classroom requires an understanding of the underlying values, beliefs, perceptions and assumptions of students, which affect their understanding of what they hear and read as well as how they express themselves in the classroom. When teachers recognize these different qualities, classroom instruction can be designed to connect content to students&rsquo; backgrounds. &nbsp;This paper examines one approach to building a teaching and learning community through faculty professional development and collaboration. It provides an overview of a 5-part workshop series conducted for faculty at the Johnson &amp; Wales University Providence campus on intercultural learning and culturally responsive teaching. Focusing on the essential components of personalizing culture through the five institutions of family, school, religion, politics, and economics through workshop activities, it is an investigation of individual and institutional backgrounds to determine how faculty may recognize the forces that influence student behavior, and how to engage them in a more active learning process

    An Analysis of the Potential for Using Over-the-Horizon Radar Systems for Space Surveillance

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    The Australian Defence Force is investigating the development of a space surveillance system. While several dedicated facilities for space surveillance are in operation around the world, Australia s Over-The-Horizon Radar (OTHR) network has some potential for this role. The OTHR operates in the HF band and is constrained by the propagation effects of the ionosphere. A spherically stratified ionospheric model and a model for a nominal OTHR antenna are developed that allow calculation of path propagation, power distribution, and clutter returns. A software-based radar receiver processing system is modeled to determine detection probabilities and the minimum detectable radar cross-section of targets in typical low earth orbit (LEO) trajectories. The high clutter power levels, coupled with long target ranges and high velocities, mean that range-Doppler tradeoffs have a great impact on the resulting detection capabilities. While the system as modeled has the potential to provide some coverage for LEO targets, operational constraints mean the necessary conditions for detection of space targets would rarely be met while the system is involved in traditional OTHR tasking. Further, the long wavelengths and large antenna beams mean the accuracy of any positioning information is low. The Australian Defence Force is investigating the development of a space surveillance system. While several dedicated facilities for space surveillance are in operation around the world, Australia\u27s Over-The-Horizon Radar (OTHR) network has some potential for this role. The OTHR operates in the HF band and is constrained by the propagation effects of the ionosphere. A spherically stratified ionospheric model and a model for a nominal OTHR antenna are developed that allow calculation of path propagation, power distribution, and clutter returns

    Soft X-ray Emission from the Spiral Galaxy NGC 1313

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    The nearby barred spiral galaxy NGC 1313 has been observed with the PSPC instr- ument on board the ROSAT X-ray satellite. Ten individual sources are found. Three sources (X-1, X-2 and X-3 [SN~1978K]) are very bright (~10^40 erg/s) and are unusual in that analogous objects do not exist in our Galaxy. We present an X-ray image of NGC~1313 and \xray spectra for the three bright sources. The emission from the nuclear region (R ~< 2 kpc) is dominated by source X-1, which is located ~1 kpc north of the photometric (and dynamical) center of NGC~1313. Optical, far-infrared and radio images do not indicate the presence of an active galactic nucleus at that position; however, the compact nature of the \xray source (X-1) suggests that it is an accretion-powered object with central mass M >~ 10^3 Msun. Additional emission (L_X ~ 10^39 erg/s) in the nuclear region extends out to ~2.6 kpc and roughly follows the spiral arms. This emission is from 4 sources with luminosity of several x 10^38 erg/s, two of which are consistent with emission from population I sources (e.g., supernova remnants, and hot interstellar gas which has been heated by supernova remnants). The other two sources could be emission from population II sources (e.g., low-mass \xray binaries). The bright sources X-2 and SN~1978K are positioned in the southern disk of NGC~1313. X-2 is variable and has no optical counterpart brighter than 20.8 mag (V-band). It is likely that it is an accretion-powered object in NGC~1313. The type-II supernova SN~1978K (Ryder \etal 1993) has become extra- ordinarily luminous in X-rays ∼\sim13 years after optical maximum.Comment: to appear in 10 Jun 1995 ApJ, 30 pgs uuencoded compressed postscript, 25 pgs of figures available upon request from colbert, whole preprint available upon request from Sandy Shrader ([email protected]), hopefully fixed unknown problem with postscript fil

    Work domain models for cognitive ergonomics: an illustration from military command and control

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    There is general agreement that ‘work’ is a primary concept for Cognitive Ergonomics (CE). However, there is little agreement how the domain of work might best be modelled. This paper assesses two contrasting approaches to such modelling. The first, and implicit approach, derives from domain experts. The second, and explicit approach, derives from domain research. The approaches are illustrated by an initial analysis of the domain of military command and control and specifically of models of the Vincennes incident. Implicit and explicit domain models are assessed in terms of the incident events. It is concluded that both models have potential to support design, but the explicit model also has potential to support research. The need for explicit domain modelling to support validation of CE design knowledge is underlined
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