3,227 research outputs found

    Magnetic field structure of the extended 3C 380 jet

    Get PDF
    An earlier study of the complex jet of 3C 380 by Papageorgiou et al. revealed total intensity and polarization structure associated with a bright knot K1 about 0.7 arcsec from the core that was reminiscent of that expected for a conical shock wave. In this new study, 1.42, 1.66 and 4.99 GHz total intensity, polarization and Faraday rotation images are presented and analysed. These images were derived from observations with the Very Long Baseline Array plus one antenna of the Very Large Array, obtained in 2006 March. These new images confirm the overall magnetic field structure of the knot K1 indicated in the earlier observations. In addition, a clear Faraday rotation gradient has been detected across the jet, extending roughly from 10 to 30 mas (70–200 pc) along the jet from the core (a radial distance of approximately two beamwidths). The gradient spans roughly 3.5 beamwidths in the transverse direction, and the difference in the rotation measures on either side of the jet is 4–5σ, demonstrating that the detection of the gradient is firm. We interpret this transverse Faraday rotation gradient as reflecting systematic variation of the line-of-sight component of a helical or toroidal magnetic field (B) associated with the jet of 3C 380. These results provide evidence that the helical field arising due to the joint action of the rotation of the central black hole and its accretion disc and the jet outflow can survive to distances of hundreds of parsecs from the central engine

    Competency-based Education in Public High Schools

    Get PDF
    Recent government-backed programs such as Race to the Top and No Child Left Behind have increased competition in schools in an effort to improve student and teacher performance. However, these programs have not had as drastic an impact as many had hoped, and the United States continues to toil in the middle of the pack educationally when compared with the rest of the world. As many students have continued to struggle in school, many different ideas have been introduced into different levels of the education system in an attempt to raise scores and boost performance. One such idea is competency-based education (CBE), which is an alternative to the traditional time-based system of public education. Rather than receiving a diploma for completing four years of high school, CBE focuses on individualization for students. Semester-long and year-long classes are replaced with a list of competencies in which students must demonstrate mastery in order to earn their diplomas. As with any other educational concept, there is just as much criticism toward CBE as there is praise. Through a literature review, I aim to describe the benefits and drawbacks of the CBE system. I lay out the advantages CBE has that the current education system lacks while simultaneously pointing out potential flaws. In addition, student and teacher survey results from a local high school are analyzed to help determine the pros and cons of the current education system. The analysis aims to overview both students\u27 and teachers\u27 receptiveness to a possible shift toward CBE. The Institutional Review Board process is also explained to display the process of getting into a school to do field work. With all of the aforementioned information being pulled together, a final letter to the high school\u27s principal and superintendent is created which outlines the final synthesis and analysis of the data. Policy recommendations are made in an attempt to help the school achieve future success. It remains largely unknown whether CBE could make a lasting positive impact on high school students. However, by extrapolating from the data presented, it is possible to begin to draw a picture of the current state of affairs as well as the possible implications and changes of a CBE system

    Efficient method for estimating the number of communities in a network

    Full text link
    While there exist a wide range of effective methods for community detection in networks, most of them require one to know in advance how many communities one is looking for. Here we present a method for estimating the number of communities in a network using a combination of Bayesian inference with a novel prior and an efficient Monte Carlo sampling scheme. We test the method extensively on both real and computer-generated networks, showing that it performs accurately and consistently, even in cases where groups are widely varying in size or structure.Comment: 13 pages, 4 figure

    (re)Structuring the agency: Agency working arrangements and social care in the era of austerity and beyond.

    Get PDF
    In Ireland, the austerity era of recent years brought (un)employment to the fore in a manner not seen since the 1980s. Within the arena of health and social care, this was epitomised by the ‘embargo’. Confined within an embargo process, recruitment agencies became a first choice response to maintaining service delivery in a deepening recessionary period. Located against this backdrop, this study explored agency-working arrangements in social care through the use of semi-structured interviews with service provider managers (n=3) and agency social care workers (n=6). Analysed using a variation of conventional content analysis; these interviews reveal a central tension between the flexibility afforded by agency working arrangements and the instability that such arrangements can foster. Although flexibility and variety in agency based employment arrangements can be beneficial for service providers, and in certain stages of career development for social care practitioners, underlying tensions arise within such working arrangements, which have a particular resonance for the social care profession. Most notably, the relationship based nature of social care practice can be disturbed by a restructuring of traditional employment pathways, especially in relation to continuity of care and practitioner support and development. Nonetheless, the findings also reveal that the extent of disruption is being dampened by adaptions to the agency process by service provider managers and social care workers through a ‘pooling’ approach to agency staffing. As such, the findings of this study both reflect common themes form literature surrounding agency working, while also observing subtle nuances. The implications of agency working for social care practice are considered, as are potential longer-term impacts given the context of impending registration of social care workers
    • …
    corecore