1,489 research outputs found
AYP Accountability Policy and Assessment Theory Conflicts
A major objective of NCLB is to hold schools accountable for student achievement including closing the achievement gap and raising standards of student academic proficiency. While the majority of individuals support the underlying values of NCLB, not all agree its accountability policy is reasonable. The most problematic issue is the mandate that schools be held accountable to ensure all students perform at grade level when the methods used by states to determine grade level proficiency preclude the attainment of this standard. The unintended consequences of a policy that does not align theoretically with established educational best practice inevitably result in frustration of educational practitioners and often unwarranted condemnation of the educational system
Understanding the Diminishing Academic Advantage of Full-Day Kindergarten
Most people agree that young children benefit academically from attending kindergarten; however, some research suggests that any academic advantage attributed to attending full-day kindergarten compared to half-day programs will disappear as early as third grade. Based on the results of this study which looked at students in typical classroom settings, a likely explanation for this is that teachers often provide considerable remedial assistance to low achieving students. Once students meet benchmark expectations, instruction tends to broaden to other instructional objectives. We also found that in practice distinguishing between full- and half-day programs based solely on time in school is problematic. Many schools offering full-day kindergarten do not provide a full day of academic instruction, and many teachers see little value of doing so
Elemental Abundances in the X-Ray Gas of Early-Type Galaxies with XMM and Chandra Observations
The source of hot gas in elliptical galaxies is thought to be due to stellar
mass loss, with contributions from supernova events and possibly from infall
from a surrounding environment. This picture predicts supersolar values for the
metallicity of the gas toward the inner part of the galaxy, which can be tested
by measuring the gas phase abundances. We use high-quality data for 10 nearby
early-type galaxy from XMM-Newton, featuring both the EPIC and the Reflection
Grating Spectrometer, where the strongest emission lines are detected with
little blending; some Chandra data are also used. We find excellent consistency
in the elemental abundances between the different XMM instruments and good
consistency with Chandra. Differences in abundances with aperture size and
model complexity are examined, but large differences rarely occur. For a
two-temperature thermal model plus a point source contribution, the median Fe
and O abundances are 0.86 and 0.44 of the Solar value, while Si and Mg
abundances are similar to that for Fe. This is similar to stellar abundances
for these galaxies but supernovae were expected to enhance the gas phase
abundances considerably, which is not observed.Comment: 35 pages, 10 figures, accepted for publication in Astrophysical
Journa
Dynamics of the infinitely-thin kink
We consider the dynamics of the domain-wall kink soliton, in particular we
study the zero mode of translation. In the infinitely-thin kink limit, we show
that the zero mode is almost completely frozen out, the only remnant being a
dynamically constrained four-dimensional mode of a single but arbitrary
frequency. In relation to this result, we show that the usual mode expansion
for dealing with zero modes -- implicit collective coordinates -- is not in
fact a completely general expansion, and that one must use instead a
traditional generalised Fourier analysis.Comment: 13 pages; v2: added references, to appear in Phys Lett
Limits on the Ununified Standard Model
The ununified standard model is an extension of the standard model that
contains separate electroweak gauge groups for quarks and leptons. When it was
originally proposed, data allowed the new gauge bosons to be quite light. We
use recent data from precision electroweak measurements to put stringent bounds
on the ununified standard model. In particular, at the 95% confidence level, we
find that the ununified gauge bosons must have masses above about 2 TeV.Comment: 14 pages, plain TeX, 2 postscript figures, figures also available at
http://smyrd.bu.edu/htfigs/figure.htm
Reply to comment on the paper by Davies et al. âResolving MISS conceptions and misconceptions: A geological approach to sedimentary surface textures generated by microbial and abiotic processesâ
We thank Noffke (2017) for her comment and for providing an opportunity to clarify our classification of âsedimentary surface texturesâ. We accord great credit to Dr. Noffke and other dedicated researchers whose detailed work has brought microbially induced sedimentary structures (MISS) to the widespread attention of geoscientists. However, we stand by our assertion that attributing structures observed in practical field and laboratory studies to processes of formation is much more problematic than Noffke (2017) indicates. Indeed, points in the Comment confirm the need for a classification system that categorises the degree of certainty attributed to a given interpretation. We stress that our paper was not designed as a critique of previous studies of MISS but rather was designed to encourage a reasonable assessment of uncertainty in assigning sedimentary surface textures to physical processes or to MISS
Resolving MISS conceptions and misconceptions: A geological approach to sedimentary surface textures generated by microbial and abiotic processes
The rock record contains a rich variety of sedimentary surface textures on siliciclastic sandstone, siltstone and mudstone bedding planes. In recent years, an increasing number of these textures have been attributed to surficial microbial mats at the time of deposition, resulting in their classification as microbially induced sedimentary structures, or MISS. Research into MISS has developed at a rapid rate, resulting in a number of misconceptions in the literature. Here, we attempt to rectify these MISS misunderstandings. The first part of this paper surveys the stratigraphic and environmental range of reported MISS, revealing that contrary to popular belief there are more reported MISS-bearing rock units of Phanerozoic than Precambrian age. Furthermore, MISS exhibit a pan-environmental and almost continuous record since the Archean. Claims for the stratigraphic restriction of MISS to intervals prior to the evolution of grazing organisms or after mass extinction events, as well as claims for the environmental restriction of MISS, appear to result from sampling bias. In the second part of the paper we suggest that raised awareness of MISS has come at the cost of a decreasing appreciation of abiotic processes that may create morphologically similar features. By introducing the umbrella term âsedimentary surface texturesâ, of which MISS are one subset, we suggest a practical methodology for classifying such structures in the geological record. We illustrate how elucidating the formative mechanisms of ancient sedimentary surface textures usually requires consideration of a suite of sedimentological evidence from surrounding strata. Resultant interpretations, microbial or non-microbial, should be couched within a reasonable degree of uncertainty. This approach recognizes that morphological similarity alone does not constitute scientific proof of a common origin, and reinstates a passive descriptive terminology for sedimentary surface textures that cannot be achieved with the current MISS lexicon. It is hoped that this new terminology will reduce the number of overly sensational and misleading claims of MISS occurrence, and permit the means to practically separate initial observation from interpretation. Furthermore, this methodology offers a scientific approach that appreciates the low likelihood of conclusively identifying microbial structures from visual appearance alone, informing the search for true MISS in Earth's geological record and potentially on other planetary bodies such as Mars
The Role and Responsibility of Physical Education:Latest Thinking Relating to Child Development and the Understanding of UK Childhood Environments
String Cosmology: A Review
The second string revolution, which begin around 1995, has led to a drastic
alteration in our perception of the universe, perhaps even more so then did the
first string revolution of 1984. That is, extending 10-dimensional string
theory to 11-dimensional M-theory has had more profound implications than did
the original extension of 4-dimensional quantum mechanics and relativity to
10-dimensional string theory. After a brief review of M-theory, I discuss some
implications of large extra dimensions. I then consider astronomical evidence
for, and constraints on, large compactified dimensions. I conclude with a
possible resolution to the apparent inconsistency between the MSSM scale and
string scale in the weak coupling limit. Talk presented at COSPAR '02, Houston,
Texas, October 2002.Comment: 10 pages. Standard Latex. Changes to match retitled published versio
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