565 research outputs found
Seasonality of Social Behaviour Among Immature Belugas (Delphinapterus leucas) in Managed Care
Belugas ( Delphinapterus leucas ) in managed care have been reported to show seasonal variation in socio-sexual behaviour, hormone levels and respiration rates; however, little is known about the social interactions of wild belugas when they are not in summer, near-shore congregations. To better understand if belugas show seasonal variation in social interactions, this study recorded the behaviour of 10 belugas (five females, five males, ranging from birth to 10 years of age) housed in managed care. Social interactions typically peaked in the summer months but persisted at very low levels during the rest of the year. Sea - sonal variation was most dramatic for socio-sexual behaviour but was generally mirrored in pattern by agonistic and affiliative interactions. Subjects closer to maturity displayed more seasonal variation than younger subjects, and males displayed more seasonal variation compared to females. The peak in social interactions found in this study aligns rather closely with wild belugasâ sum - mer, near-shore congregations, where belugas have increased opportunities for socializing. Although belugas in managed care do not experience a seasonal change in habitat, they do show seasonal changes in social behaviour, which are likely driven by seasonal fluctuations in hormone levels. It is therefore expected that wild beluga populations would show similar behavioural pat - terns if they were observed throughout the remainder of the year. This research has applications for belugas in managed care and may provide a framework for understanding the social behaviour of wild belugas
Teacher Quality and Quality Teaching: Examining the Relationship of a Teacher Assessment to Practice
Do the nearby BHB stars belong to the Thick Disk or the Halo?
We study the Milky Way region Z<3.0 kpc, where the thick disk and inner halo
overlap, by using the kinematics of local blue horizontal branch (BHB) stars
(within 1 kpc) and new samples of BHB stars and A-type stars from the Century
Survey. We derive Galactic U,V,W velocities for these BHB and A-type star
samples using proper motions from the NOMAD catalog. The mean velocities and
the velocity dispersions of the BHB samples (Z<3 kpc) are characteristic of the
halo, while those of the Century Survey A-type stars are characteristic of the
thick disk. There is no evidence from our samples that the BHB stars rotate
with the thick disk in the region Z<3 kpc. Nearly a third of the nearby local
RR Lyrae stars have disk kinematics and are more metal-rich than [Fe/H]~-1.
Only a few percent of the Century Survey BHB stars have these properties. Only
one nearby BHB star (HD 130201) is likely to be such a disk star but selection
based on high proper motions will have tended to exclude such stars from the
local sample. The scale height derived from a sample of local RR Lyrae stars
agrees with that of the Century Survey BHB stars. The local samples of BHB
stars and metal-weak red giants are too incomplete for a similar comparison.Comment: 14 pages, accepted to A
Examining High and Low Value-Added Mathematics Instruction: Can Expert Observers Tell the Difference
The question of how to measure effective teachers and teaching has long been of interest to policymakers and school leaders. While recent policy initiatives have focused on the use of value-added measures (VAM) to assess teacher quality, there is a much longer tradition of using observations of practice to make such determinations. However, empirical evidence suggests these two indicators often identify different sets of teachers as effective. For example, the Measures of Effective Teaching project finds low correlations between teachersâ VAM scores and their quality of instruction as measured by observational metrics. Studies with the explicit intent of identifying differences in instruction between teachers with high and low VAM scores also have generally failed to uncover substantial differences across classrooms.
In this study, we take advantage of a dataset containing both videotaped lessons and value-added scores to mount an exploratory study of the instruction of teachers with high- and low-value-added rankings. Specifically, we seek to answer two questions: First, what is the degree of convergence between observersâ impressions of mathematics instruction and teachersâ mathematics value-added scores? Second, are there a set of instructional practices that consistently characterize high but not low-value-added ranked teachersâ classrooms, and vice versa
Nonconventional Quantized Hall Resistances Obtained with Μ = 2 Equilibration in Epitaxial Graphene p-n Junctions
We have demonstrated the millimeter-scale fabrication of monolayer epitaxial graphene pân junction devices using simple ultraviolet photolithography, thereby significantly reducing device processing time compared to that of electron beam lithography typically used for obtaining sharp junctions. This work presents measurements yielding nonconventional, fractional multiples of the typical quantized Hall resistance at Îœ=2 (RHâ12906Ω) that take the form: (a/b)RH. Here, a and b have been observed to take on values such 1, 2, 3, and 5 to form various coefficients of RH. Additionally, we provide a framework for exploring future device configurations using the LTspice circuit simulator as a guide to understand the abundance of available fractions one may be able to measure. These results support the potential for drastically simplifying device processing time and may be used for many other two-dimensional materials
Troubling "understanding mathematics-in-depth": Its role in the identity work of student-teachers in England
Copyright @ The Author(s) 2013. This article is published with open access at Springerlink.comThis article has been made available through the Brunel Open Access Publishing Fund.In this paper, we focus on an initiative in England devised to prepare non-mathematics graduates to train as secondary mathematics teachers through a 6-month Mathematics Enhancement Course (MEC) to boost their subject knowledge. The course documentation focuses on the need to develop âunderstanding mathematics in-depthâ in students in order for them to become successful mathematics teachers. We take a poststructural approach, so we are not interested in asking what such an understanding is, about the value of this approach or about the effectiveness of the MECs in developing this understanding in their participants. Instead we explore what positions this discourse of âunderstanding mathematics in-depthâ makes available to MEC students. We do this by looking in detail at the âidentity workâ of two students, analysing how they use and are used by this discourse to position themselves as future mathematics teachers. In doing so, we show how even benign-looking social practices such as âunderstanding mathematics in-depthâ are implicated in practices of inclusion and exclusion. We show this through detailed readings of interviews with two participants, one of whom fits with the dominant discourses in the MEC and the other who, despite passing the MEC, experiences tensions between her national identity work and MEC discourses. We argue that it is vital to explore âidentity workâ within teacher education contexts to ensure that becoming a successful mathematics teacher is equally available to all.Kingâs College Londo
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