11,935 research outputs found
Developing a New Partnership
Many factors contribute to the success and impact of a Mathematics Resource Teacher on K-5 mathematics instruction. Developing a strong partnership with stakeholders and sharing a common vision for quality mathematics instruction are key factors in the successful implementation of the Mathematics Resource Teacher program. In this article, we share the experience of elementary school principal, Timothy Martino, as he prepared to open a new elementary school in August 2012. Frederick Douglass Elementary opened with a full-time, school-embedded Mathematics Resource Teacher, Mrs. Cindy Brady. Timothy Martino and Mrs. Brady developed a partnership with division-level central office staff and with the teachers of Frederick Douglass Elementary. Thus, they began the journey toward improving mathematics instruction for students through a team approach
Understanding Variations in Circularly Polarized Photoluminescence in Monolayer Transition Metal Dichalcogenides
Monolayer transition metal dichalcogenides are promising materials for
valleytronic operations. They exhibit two inequivalent valleys in the Brillouin
zone, and the valley populations can be directly controlled and determined
using circularly polarized optical excitation and emission. The
photoluminescence polarization reflects the ratio of the two valley
populations. A wide range of values for the degree of circularly polarized
emission, Pcirc, has been reported for monolayer WS2, although the reasons for
the disparity are unclear. Here we optically populate one valley, and measure
Pcirc to explore the valley population dynamics at room temperature in a large
number of monolayer WS2 samples synthesized via chemical vapor deposition.
Under resonant excitation, Pcirc ranges from 2% to 32%, and we observe a
pronounced inverse relationship between photoluminescence (PL) intensity and
Pcirc. High quality samples exhibiting strong PL and long exciton relaxation
time exhibit a low degree of valley polarization, and vice versa. This behavior
is also demonstrated in monolayer WSe2 samples and transferred WS2, indicating
that this correlation may be more generally observed and account for the wide
variations reported for Pcirc. Time resolved PL provides insight into the role
of radiative and non-radiative contributions to the observed polarization.
Short non-radiative lifetimes result in a higher measured polarization by
limiting opportunity for depolarizing scattering events
Statistical analysis of the 70 meter antenna surface distortions
Statistical analysis of surface distortions of the 70 meter NASA/JPL antenna, located at Goldstone, was performed. The purpose of this analysis is to verify whether deviations due to gravity loading can be treated as quasi-random variables with normal distribution. Histograms of the RF pathlength error distribution for several antenna elevation positions were generated. The results indicate that the deviations from the ideal antenna surface are not normally distributed. The observed density distribution for all antenna elevation angles is taller and narrower than the normal density, which results in large positive values of kurtosis and a significant amount of skewness. The skewness of the distribution changes from positive to negative as the antenna elevation changes from zenith to horizon
A descriptive study of the tones in the Chengtu dialect (Szechuan, China) and the intonation of certain types of sentences
First, tones pronounced in isolation behave
differently from those pronounced in connected
speech. In connected speech they go through
perturbation. This is usually governed by the
position they occupy in the phrase or by the tonal
environment. It may also be governed by grammatical
structure, though this does not form part of my
present inquiry.Second, besides the four naming tones in the
Chengtu dialect, I found six other tones which,
together with those naming tones, could be grouped
into four tonemes. It is the interchange of these
tones which formed the study of the tonal behaviour
in the first part of this thesis.Third, intonation does exist in the Chengtu
dialect. It is superimposed on the whole sentence.
And it is this superimposed intonation that modifies
the individual tones and not the individual tones
that decide the intonation of the sentence.My purpose in undertaking this study has been
twofold. On one hand, it is my hope that the work
may serve as a teaching manual for intonation
in the Chengtu dialect. In the process of
acquiring the right intonation, the advanced
student may find the numerous examples useful.
Though they are taken only from the speech of
two people (the informant and myself), they
more or less represent the main speech characteristics
of the Chengtu dialect.Oh the other hand, the material I assembled
and particularly the conclusions I reached may be
of some value to students of other dialects. Tone
sandhi has already been studied in many Chinese
dialects , though without the help of the more
modern instruments. It would be desirable for
similar work to be done on A
eresting question is whether in other dialects intonation
is also indicated by the perturbation of
one particular syllable, which in the case of the
Chengtu dialect is the final syllable. It would
also be interesting to know if the resulting tunes
could be divided neatly into two or more patterns.
If a number of other dialects could be studied
along lines similar to the present inquiry, we could
then perhaps come to a more general explanation of
tonal behaviour and intonation in the Chinese dialects
Where are the Hedgehogs in Nematics?
In experiments which take a liquid crystal rapidly from the isotropic to the
nematic phase, a dense tangle of defects is formed. In nematics, there are in
principle both line and point defects (``hedgehogs''), but no point defects are
observed until the defect network has coarsened appreciably. In this letter the
expected density of point defects is shown to be extremely low, approximately
per initially correlated domain, as result of the topology
(specifically, the homology) of the order parameter space.Comment: 6 pages, latex, 1 figure (self-unpacking PostScript)
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