25,281 research outputs found

    X-ray Emission Processes in Extragalactic Jets, Lobes and Hot Spots

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    This paper is a brief review of the processes responsible for X-ray emission from radio jets, lobes and hot spots. Possible photons in inverse Compton scattering models include the radio synchrotron radiation itself (i.e. synchrotron self-Compton [SSC] emission), the cosmic microwave background (CMB), the galaxy starlight and radiation from the active nucleus. SSC emission has been detected from a number of hot spots. Scattering of the CMB is expected to dominate for jets (and possibly hot spots) undergoing bulk relativistic motion close to the direction towards the observer. Scattering of infrared radiation from the AGN should be observable from radio lobes, especially if they are close to the active nucleus. Synchrotron radiation is detected in some sources, most notably the jet of M87. I briefly discuss why different hot spots emit X-rays by different emission mechanisms and the nature of the synchrotron spectra.Comment: To be published in the proceedings of the Bologna conference ``The Physics of Relativistic Jets in the Chandra and XMM Era'', New Astronomy Revie

    Ripples of Gratitude: The Flow-on Effects of Practicing Gratitude in the Classroom Environment

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    This research explores God’s call to gratitude, summarizes current research on the benefits of gratitude, identifies key gratitude disciplines/practices, and utilizes a conceptual framework to study gratitude in the context of educational settings. In contribution to the relatively recent discussion on gratitude, especially in the education field, the researchers explored the effects when pre-service teachers practice an inner attitude of gratitude and intentionally express gratitude in the classroom setting. This study expands the current educational research of gratitude by incorporating three primary gratitude practices – the State of Preparedness, gratitude language, and gratitude journaling – and examining both personal benefits and flow-on effect toward the teaching-learning process. Fourteen pre-service elementary school teachers were invited to practice gratitude during nine weeks of their full-time fieldwork placements. Participants experienced personal benefits such as enhanced well-being, strengthened relationships, and heightened cognitive skills. Ripples of gratitude were observed as positive flow-on effects in their classrooms: a more positive and calmer classroom atmosphere, better behaved students, and students more willing to focus effort towards learning. Pre-service teachers also experienced a flow-on effect towards themselves through increased resiliency when facing adversity and greater satisfaction in teaching. These findings are significant for the field of education as the power of gratitude can foster positive transformation through promoting engaged environments and strengthened relationships for both teacher and student

    Optical system for space simulator Patent Application

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    Optical system for increasing light beam intensity within solar simulator

    Interview with Wilson Harris

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    Michel Fabre interviewed Wilson Harris in January 1979

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    Pruning deciduous fruit trees /

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    ‘Sleep-Walking Towards Segregation’? The Changing Ethnic Composition of English Schools, 1997-2003 – an Entry Cohort Analysis

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    There has been considerable public debate recently in England regarding levels of segregation (and changes in those levels) not only by neighbourhood but also in schools. Little data are available to evaluate claims that such segregation has been increasing in the country’s schools. This paper uses a data set released by the Department for Education and Skills which indicates the ethnic identity for every student in the entry cohorts for all English primary and secondary schools between 1997-8 (for primary and secondary schools respectively) and 2003. Analysis indicates that there has been some increase in segregation levels in some cities, but only to the expected extent given the changing relative size of the ethnic minority populations there. Segregation is relatively high there, but has only increased if the minority groups’ share of the entry cohorts has been increasing.ethnic segregation, schools

    A Description of New Teacher Induction Programs in the State of Georgia

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    The purpose of this study was to descriptively analyze new teacher induction programs across the state of Georgia regarding the support programs school districts provided for new teachers. Subjects for this study were 500 randomly selected Georgia teachers who completed their first year of teaching during the 1999-2000 school year. Participation in this study required that the subjects complete and return a survey developed in 1990 by Dr. Shelby Talley and modified by the researcher for this study. There were 327 surveys returned with a collective response rate of 65.4%. This study found that induction practices to socialize new teachers in Georgia wer weak in the areas of providing building tours, introducing the novices to building personnel, securing housing and providing information about the community. Most teachers were assigned mentors, but many were described by survey participants as ineffective, unavailable, and as teaching in a different grade level. Data regarding assignment factors revealed that most teachers were assigned to teaching positions reflective of their training and education and were assigned to a classroom rather than floating between classrooms. However, this study\u27s results verified that special considerations are not common in the state of Georgia regarding the types of students assigned to new teachers, reduction in workloads, or reduction in class sizes. Regarding the professional needs of teachers, most new teachers were provided adequate information about the evaluation process, appropriate feedback regarding their performance, and school norms were clearly communicated. However, the majority of new teachers were not provided with curricula in a timely manner, new teacher handbooks, or opportunities to observe others and to be observed. The majority of new teachers surveyed in the state of Georgia, 41.3%, recommended continuing the induction program in their school districts with minor modifications. There were 19% of the participants who recommended major modifications to the program, and 7% recommended replacing the existing program completely. There were 443 qualitative responses received from participants identifying concerns, needs, and suggestions for future program improvement

    A compilation and critical analysis of music composed originally for flute

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    It is the purpose of this study to organize the music written originally for flute and available in this country on the basis of a critical analysis which will give the reader a brief but authoritative word picture of each composition listed. This includes only music for C flute or without piano accompaniment. There are no arrangements or transcriptions included

    Two Populations of Young Massive Star Clusters in Arp 220

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    We present new optical observations of young massive star clusters in Arp 220, the nearest ultraluminous infrared galaxy, taken in UBVI with the Hubble Space Telescope ACS/HRC camera. We find a total of 206 probable clusters whose spatial distribution is centrally concentrated toward the nucleus of Arp 220. We use model star cluster tracks to determine ages, luminosities, and masses for 14 clusters with complete UBVI indices or previously published near-infrared data. We estimate rough masses for 24 additional clusters with I < 24 mag from BVI indices alone. The clusters with useful ages fall into two distinct groups: a ``young'' population (< 10 Myr) and an intermediate-age population (~300 Myr). There are many clusters with masses clearly above 10^6 Msun and possibly even above 10^7 Msun in the most extreme instances. These masses are high enough that the clusters being formed in the Arp 220 starburst can be considered as genuine young globular clusters. In addition, this study allows us to extend the observed correlation between global star formation rate and maximum cluster luminosity by more than an order of magnitude in star formation rate.Comment: 30 pages, 8 figures; figs 1-3 in color; accepted to Ap
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