3,433 research outputs found
e-EVN radio detection of Aql X-1 in outburst
The neutron star X-ray binary Aql X-1 is currently in outburst. Using the European VLBI Network (e-EVN) we observed Aql X-1 at 5 GHz in two time-slots: 2013 June 18 between 19:48 - 20:36 UT (MJD 56461.825 - 56461.858), and 2013 June 19 between 02:53 - 05:54 UT (MJD 56462.120 - 56462.246). The two datasets were combined together and then calibrated
On the stability of a heated rotating-disk boundary layer in a temperature-dependent viscosity fluid
The paper presents a linear stability analysis of the temperature-dependent boundary-layer flow over a rotating disk. Gas- and liquid-type responses of the viscosity to temperature are considered, and the disk rotates in both a quiescent and an incident axial flow. Temperature-dependent-viscosity flows are typically found to be less stable than the temperature independent cases, with temperature dependences that produce high wall viscosities yielding the least stable flows. Conversely, increasing the incident axial flow strength produces greater flow stability. Transitional Reynolds numbers for these flows are then approximated through an eN-type analysis and are found to vary in approximate concordance with the critical Reynolds number. Examination of the component energy contributions shows that flow stability is affected exclusively through changes to the mean flow. The results are discussed in the context of chemical vapor deposition reactors
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Rooting the Study of Communication Activism in an Attempted Book Ban
Cultivating deeply rooted community partnerships is vital to the mission of teaching and scholarship that answers the call for robust civic learning and democratic engagement. This paper recognizes that such teaching and research, particularly when it delves into political and contested questions, may provoke criticism and skepticism. So, for those scholars and their students who enter the fray of political action, we argue that the move may be eased and nurtured with strong, sustained university-community partnerships built upon support, action, and, importantly, a commitment to common cause. We argue that unexpected moments in public life can create opportunities to stretch and strengthen those relationships to invigorate our democracy if we have done the work previously to think about, express, and challenge our thinking about what we owe to our communities
Make Your Escape: Experiences with Gamified Library Programming
To increase student engagement, the Humboldt State University Library ventured into the realm of gamified programming, exploring several strategies with the goal of trans- forming library outreach and instruction. Our efforts range from simple outreach to highly structured information literacy instruction and workshops that use gamification to encourage students to engage with knowledge practices and dispositions outlined in the ACRL Framework for Information Literacy for Higher Education. Using gamified activities in library instruction led us to create lesson plans that are purely game-based, including escape room drop-in sessions where students race against the clock to solve a series of puzzles in order to “escape” the room. This model aimed to promote collaboration and problem-solving skills through inquiry-based learning
An outburst of SS 433 observed on milliarcsecond scale
SS 433 is a high-mass X-ray binary system (XRB) and one of the most persistent sources of relativistic jets in the Milky Way. The object has been intensively studied in radio at arcsecond scales, however the high-resolution observations (i.e. VLBI) are relatively scarce. In 2008 November the system was in outburst. Using the e-VLBI capabilities of the European VLBI Network (EVN) we observed SS 433 for three epochs during the active phase. The data offered a detailed view of the system’s behaviour in outburst at milliarcsecond scales. We used the “kinematic model" (which predicts the position along the jet of any knot ejected at some particular time in the past) to investigate the dynamic parameters of SS 433 and we examined the polarization properties of the ejected material. We report here the preliminary results
Coaching Elementary Teachers in Literacy: Does Feedback Type Matter for Low Implementers?
For literacy coaches and teachers, feedback is an integral component of effective coaching. Yet, little is understood about the interaction between feedback and high/low implementing teachers within coaching sessions. This multiple case study explored the types of feedback literacy coaches provided both high and low implementing teachers over a two-year period. In the first year, the literacy coaches provided at least twice as much instructional feedback as emotional feedback to low-implementing teachers. Those teachers not only received more feedback in general, but the feedback they received was primarily what they needed to do to improve. In contrast, during the same period literacy coaches provided high-implementing teachers more emotional feedback than instructional feedback. Low implementation, or resistance, observed in this study may have been tied to the overwhelming amount and type of feedback the low implementing teachers received. Coaches seeking to enhance instructional practices could benefit from attending to the amount and type of feedback they provide their learners.
CONTRIBUTIONS OF THE AXIAL SPINE TO KICKING BIOMECHANICS IN THE DIPPING KICK AMONG ELITE SOCCER PLAYERS
The aim of this study was to develop normative data for thoracic, lumbar and pelvic range of motion (ROM) during a soccer dipping kick among five NCAA Division I and high-level youth soccer players, comparing successful and unsuccessful kicks. The “dipping” kick is a complex, skill whereby a player strikes the ball so that it initially rises, but due to its top spin subsequently “dips” toward the intended target. From a repeated measures, cross-sectional design, successful kicks had a lower thoracic rotation at ball contact and average maximum thoracic rotation at 31.1±26.5º compared to the average maximum value for unsuccessful kicks at 43.7±28.6º, although not statistically significant. This study suggests that twisting the thoracic spine away from the target in an effort to “whip” and dip the ball may be suboptimal. The thoracic spine is more in line with the pelvis in successful kicks
A game-based online tool to measure cognitive functions in students
Cognitive assessments can be expensive, lengthy and fatiguing for students and are often conducted in an artificial clinical context. In an effort to make the assessments more fun, researchers have started to introduce game elements to traditional cognitive tasks and training. This comes with a number of challenges. The main challenge is to develop an engaging tool that at the same time reliably assesses cognitive constructs in students. To address these challenges, this research aims to improve cognitive assessment with a new game-based assessment app that has been designed and developed in collaboration with researchers, teachers, students, and software engineers based on established cognitive theories, and subsequently validated through iterative testing in real world settings. The iterative development process is based on design-based research and includes cycles of design explorations, testing, analyses, redesign, and evaluation with students in authentic educational settings. The knowledge gained from the iterative process of designing a valid cognitive function app can inform other researchers who are aiming to develop cognitive assessment tools in an educational context
The VLA Survey of the Chandra Deep Field South: I. Overview of the Radio Data
We report 20 and 6 cm VLA deep observations of the CDF-S including the
Extended CDF-S. We discuss the radio properties of 266 cataloged radio sources,
of which 198 are above a 20 cm completeness level reaching down to 43 microJy
at the center of the field. Survey observations made at 6 cm over a more
limited region covers the original CDF-S to a comparable level of sensitivity
as the 20 cm observations.
Of 266 cataloged radio sources, 52 have X-ray counterparts in the CDF-S and a
further 37 in the E-CDF-S area not covered by the 1 Megasecond exposure. Using
a wide range of material, we have found optical or infrared counterparts for
254 radio sources, of which 186 have either spectroscopic or photometric
redshifts (Paper II). Three radio sources have no apparent counterpart at any
other wavelength. Measurements of the 20 cm radio flux density at the position
of each CDF-S X-ray source detected a further 30 radio sources above a
conservative 3-sigma detection limit.
X-ray and sub-mm observations have been traditionally used as a measure of
AGN and star formation activity, respectively. These new observations probe the
faint end of both the star formation and radio galaxy/AGN population, as well
as the connection between the formation and evolution of stars and SMBHs. Both
of the corresponding gravitational and nuclear fusion driven energy sources can
lead to radio synchrotron emission. AGN and radio galaxies dominate at high
flux densities. Although emission from star formation becomes more prominent at
the microjansky levels reached by deep radio surveys, even for the weakest
sources, we still find an apparent significant contribution from low luminosity
AGN as well as from star formation.Comment: Accpted for publication in the Astrophysical Journal supplements with
3 tables and 18 figure
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