464 research outputs found
Reform of High School Mathematics and Science and Opportunity to Learn
This brief concerns the nature of the high school mathematics and science curriculum in the United States. It draws from a large study which documented instructional practices and content using novel methodologies. This research approach is a promising step toward the development of indicators of opportunity to learn. The study also provides encouraging news about the effects of increased standards in math and science - they did not result in a watering down of the curriculum. However, practice in the schools studied is a far cry from the ambitious goals for math and science instruction now being developed by the profession
Magnetic properties of photospheric regions having very low magnetic flux
The magnetic properties of the quiet Sun are investigated using a novel
inversion code, FATIMA, based on the Principal Component Analysis of the
observed Stokes profiles. The stability and relatively low noise sensitivity of
this inversion procedure allows for the systematic inversion of large data sets
with very weak polarization signal. Its application to quiet Sun observations
of network and internetwork regions reveals that a significant fraction of the
quiet Sun contains kilogauss fields (usually with very small filling factors)
and confirms that the pixels with weak polarization account for most of the
magnetic flux. Mixed polarities in the resolution element are also found to
occur more likely as the polarization weakens.Comment: To apapear in ApJ. 39 pages, 12 figures (2 of them are color figures
Quiet Sun magnetic fields from simultaneous inversions of visible and infrared spectropolarimetric observations
We study the quiet Sun magnetic fields using spectropolarimetric observations
of the infrared and visible Fe I lines at 6301.5, 6302.5, 15648 and 15653 A.
Magnetic field strengths and filling factors are inferred by the simultaneous
fit of the observed Stokes profiles under the MISMA hypothesis. The
observations cover an intra-network region at the solar disk center. We analyze
2280 Stokes profiles whose polarization signals are above noise in the two
spectral ranges, which correspond to 40% of the field of view. Most of these
profiles can be reproduced only with a model atmosphere including 3 magnetic
components with very different field strengths, which indicates the
co-existence of kG and sub-kG fields in our 1.5" resolution elements. We
measure an unsigned magnetic flux density of 9.6 G considering the full field
of view. Half of the pixels present magnetic fields with mixed polarities in
the resolution element. The fraction of mixed polarities increases as the
polarization weakens. We compute the probability density function of finding
each magnetic field strength. It has a significant contribution of kG field
strengths, which concentrates most of the observed magnetic flux and energy.
This kG contribution has a preferred magnetic polarity, while the polarity of
the weak fields is balanced.Comment: 16 pages and 14 figure
Breeding for resistance, to Heliothis armigera in chickpea
Chickpea (Cicer ariethtim L) is a mandate crop of International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). The crop has fewer pest problems khan other legumes, Heliothis arimgtra is the major past in most chickpea growing areas and is polyphagous attacking many crop species
The distribution of Quiet Sun magnetic field strengths from 0 to 1800 G
The quiet Sun photospheric plasma has a variety of magnetic field strengths
going from zero to 1800 G. The empirical characterization of these field
strengths requires a probability density function (PDF), i.e., a function P(B)
describing the fraction of quiet Sun occupied by each field strength B. We show
how to combine magnetic field strength measurements based on the Zeeman effect
and the Hanle effect to estimate an unbiased P(B). The application of the
method to real observations renders a set of possible PDFs, which outline the
general characteristics of the quiet Sun magnetic fields. Their most probable
field strength differs from zero. The magnetic energy density is a significant
fraction of the kinetic energy of the granular motions at the base of the
photosphere (larger than 15% or larger than 2 10^{3} erg cm^{-3}). The unsigned
flux density (or mean magnetic field strength) has to be between 130 G and 190
G. A significant part of the unsigned flux (between 10% and 50%) and of the
magnetic energy (between 45% and 85%) are provided by the field strengths
larger than 500 G which, however, occupy only a small fraction of the surface
(between 1% and 10%). The fraction of kG fields in the quiet Sun is even
smaller, but they are important for a number of reasons. The kG fields still
trace a significant fraction of the total magnetic energy, they reach the high
photosphere, and they appear in unpolarized light images. The quiet Sun
photosphere has far more unsigned magnetic flux and magnetic energy than the
active regions and the network all together.Comment: To appear in ApJ. 14 pages, 9 figure
Mutations in GATA2 cause primary lymphedema associated with a predisposition to acute myeloid leukemia (Emberger syndrome).
We report an allelic series of eight mutations in GATA2 underlying Emberger syndrome, an autosomal dominant primary lymphedema associated with a predisposition to acute myeloid leukemia. GATA2 is a transcription factor that plays an essential role in gene regulation during vascular development and hematopoietic differentiation. Our findings indicate that haploinsufficiency of GATA2 underlies primary lymphedema and predisposes to acute myeloid leukemia in this syndrome
Researching the home using architectural and social science methods
This article explores the possibilities of using innovative, interdisciplinary methods for understanding home-making. Drawing on a study of Claremont Court (1959â1962), a post-war social housing scheme designed by Sir Basil Spence in Edinburgh, we discuss the methodological potentials of combining architectural and social science methods to study the home. Claremont Court was built in the post-war era as part of Scotlandâs social housing drive. It was designed following the principles of âcross-classâ living in order to foster a sense of community. In subsequent years, inhabitants of the court have adapted their dwellings in numerous ways and the population of the court has changed dramatically. But, while meanings of home and understandings of the division between public and private have been reconfigured, the spatial layouts of the dwellings continue to shape residentsâ sense of home. To explore how residents make home at Claremont Court, we use âfacet methodologyâ, which opens up new ways of thinking about the research process through a âplayfulâ approach to epistemology. In doing so, we develop an innovative approach which combines architectural methods (including survey drawings and visual mappings of both dwellings and communal areas) with social science methods (including âtraditionalâ interviews and walk-along interviews). To conclude, we discuss the possibility of widening the scope of qualitative research by bringing architectural and social science methods into dialogue through visual methods, in order to attend to spatial and material aspects of the home. We argue that our novel cross-disciplinary approach broadens understandings of home, by bringing attention to the unspoken dimensions of physical space, embodied elements of home and what people said about their homes, all of which are central to home-making
Changing antiepilepsy drug-prescribing trends in women with epilepsy in the UK and Ireland and the impact on major congenital malformations
Objectives: After 20 years of data collection, pregnancy registers have informed prescribing practice. Various populations show trends for a reduction in valproate prescribing, which is associated with an increased risk of anatomical teratogenesis and neurodevelopmental effects in those exposed in utero. Our aim was to determine if any shifts in prescribing trends have occurred in the UK and Ireland Epilepsy and Pregnancy Register cohort and to assess if there had been any change in the overall major congenital malformation (MCM) rate over time. Methods: The UK and Ireland Epilepsy and Pregnancy Register, a prospective, observational, registration and follow-up study established in 1996, was used to determine the changes in antiepileptic drugs (AEDs) utilised during pregnancy and the MCM rate between 1996 and 2016. Linear regression analysis was used to assess changes in AED utilisation, and Poisson regression was used for the analysis of trends in the MCM rates. Results: Outcome data for 9247 pregnancies showed a stable percentage of monotherapy to polytherapy prescribing habits over time. After Bonferroni correction, statistically significant (p<0.003) changes were found in monotherapy prescribing with increases in lamotrigine and levetiracetam and decreases in valproate and carbamazepine use. Between 1996 and 2016, the total MCM rate showed a 2.1% reduction per year (incidence risk ratio 0.979 (95% CIs 0.956 to 1.002) but Poisson regression analysis showed that this was not statistically significant p=0.08). Conclusion: Significant changes are seen in the prescribing habits in this cohort over 20 years, but a statistically significant change in the MCM rate was not detected. This work should be replicated on a larger scale to determine if significant changes are occurring in the MCM rate, which would allow a robust economic estimate of the benefits of improvements in prescribing practice and the personal effect of such changes
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