18,529 research outputs found
Preparing Tomorrow’s World Language Teacher Today: The Case for Seamless Induction
This essay is a call to action. It offers a comprehensive overview of the challenges facing world language (WL) teacher educators and their employers, the K-12 schools, during the teacher induction period. We propose a new paradigm for WL teacher education based on national accreditation standards, best-practice pedagogy, insights from the professional literature on methods education, and the enhanced role of the methods instructor/supervisor. In order to become successful in the classroom, the pre-service educator undergoes a seamless period of induction that is student-centered and college/university-supported beyond the classroom arena
Global and Unified Analysis of Solar Neutrino Data
We discuss the status of the solutions of the solar neutrino problem in terms
of oscillations of into active or sterile neutrinos. We present the
results of a global fit to the full data set corresponding to the latest data
presented at the -2000 conference. We show the possible solutions in the
full parameter space including both MSW and vacuum, as well as quasi-vacuum
oscillations (QVO) and matter effects for mixing angles in the second octant
(the so called dark side). Our conclusion is that from the statistical point of
view, all solutions for oscillations into active neutrinos: LMA, LOW, SMA and
the QVO solutions are acceptable since they all provide a reasonable GOF to the
full data set. The same holds for the SMA solution for oscillations into
sterile neutrinos. LMA and LOW-QVO solutions for oscillations into active
neutrinos seem slightly favoured over SMA solutions for oscillations into
active or sterile neutrinos. We also analyze the dependence of these
conclusions on the uncertainty of the SSM B flux and on the removal of the
data from one of the experimental rates. We also present the results in the
framework of four neutrino oscillations which allows for oscillations into a
state which is a combination of active and sterile neutrino.Comment: 18 pages with 18 postscript figures included (some of them bitmapped
for compression, better resolution at http://ific.uv.es/~penya
Genetic consequences of artificial selection on amino acid synthesis: Cysteine synthase and chorismate mutase
Abstract only availableFaculty Mentor: Michael D. McMullen, AgronomyGenetic diversity is crucial for progress in plant breeding as well as for adaptation to future
environmental challenges. Maize is the most genetically diverse crop species. Maize was
domesticated from teosinte about 7,500 years ago. Both domestication and crop improvement
involved selection of specific alleles at genes controlling key morphological and agronomic traits,
resulting in reduced genetic diversity relative to unselected genes. The McMullen Laboratory is
interested in the genetic consequences of selection on genes of agronomic importance. Prior
research by the Laboratory has identified a series of selected genes, including two key genes for the
synthesis of amino acids, cysteine synthase and chorismate mutase. One approach to define the
importance of a gene is to isolate a mutation and examine the resulting phenotype. A Mutator
insertion was isolated in the cysteine synthase gene. An F2 population segregating for an albino
phenotype and the Mutator insertion was genotyped by PCR to determine if the insertion was casual
for the phenotype. The albino phenotype was found to be closely linked, but distinct from the
insertion site leading to the conclusion that the albino phenotype is caused by a second linked
mutation. The chorismate mutase gene in maize shows strong evidence of selection, with high
diversity in teosinte accessions and essentially no diversity among inbred lines. Did the selection
that reduced the diversity in this gene occur at domestication or during subsequent plant breeding?
To answer this question, three segments of the chorismate mutase gene were sequenced in a panel
of 14 landraces, the historical intermediate between teosinte and inbreds. Four landraces contained
numerous polymorphism not found in inbreds, indicating that much of the selection occurred during
recent crop improvement. This result is significant as it indicates genetic diversity can be
reintroduced into selected amino acid genes by crosses with landraces
Kadath: a spectral solver for theoretical physics
Kadath is a library that implements spectral methods in a very modular
manner. It is designed to solve a wide class of problems that arise in the
context of theoretical physics. Several types of coordinates are implemented
and additional geometries can be easily encoded. Partial differential equations
of various types are discretized by means of spectral methods. The resulting
system is solved using a Newton-Raphson iteration. Doing so, Kadath is able to
deal with strongly non-linear situations. The algorithms are validated by
applying the library to four different problems of contemporary physics, in the
fields of gauge field theory and general relativityComment: Accepted to Journal of Computational Physic
Association Between Weight Loss and Physical Activity On Change In Blood Pressure In Overweight Adults
Please view abstract in the attached PDF file
Non-equilibrium Goldstone phenomenon in tachyonic preheating
The dominance of the direct production of elementary Goldstone waves is
demonstrated in tachyonic preheating by numerically determining the evolution
of the dispersion relation, the equation of state and the kinetic power spectra
for the angular degree of freedom of the complex matter field. The importance
of the domain structure in the order parameter distribution for the
quantitative understanding of the excitation mechanism is emphasized. Evidence
is presented for the very early decoupling of the low-momentum Goldstone modes.Comment: 14 LaTeX pages, 5 figures, version published in Phys. Rev.
Recommended from our members
Hypoimmunogenic Derivatives of Induced Pluripotent Stem Cells Evade Immune Rejection in Fully Immunocompetent Allogeneic Recipients
Standard and Non-Standard Physics in Neutrino Oscillations
We analyze the impact of recent solar and atmospheric data in the
determination of the neutrino oscillation parameters, taking into account that
both the solar nu_e and the atmospheric nu_mu may convert to a mixture of
active and sterile neutrinos. Furthermore, in the context of the atmospheric
neutrino problem we discuss an extended mechanism of neutrino propagation which
combines both oscillations and non-standard neutrino-matter interactions. We
use the most recent neutrino data, including the 1496-day Super-K solar and
atmospheric data samples, the latest SNO spectral and day/night solar data, and
the final MACRO atmospheric results. We confirm the clear preference of all the
data for pure-active oscillation solutions, bounding the fraction of sterile
neutrino involved in oscillations to be less than 52% in the solar sector and
less than 40% in the atmospheric sector, at 3 sigma. For the atmospheric case
we also derive a bound on the total amount of non-standard neutrino-matter
interactions, bounding the flavor-changing component to -0.03 <= epsilon <=
0.02 and the non-universal component to |epsilon'| <= 0.05.Comment: 6 pages, LaTeX file using espcrc2.sty, 1 table and 3 figures
included. Talk given at the XXX International Meeting on Fundamental Physics
(Jaca, Spain, 28/01-1/02/2002
Constraints on neutrino oscillation parameters from the SNO salt phase data
The physics implications of the just published salt phase data from the SNO
experiment are examined. The effect of these data on the allowed ranges of the
solar neutrino oscillation parameters, \Delta_m^2_{21} and
, are studied in the cases of two- and three- neutrino
mixing. In the latter case we derive an upper limit on the angle .
Constraints on the solar transitions into a mixture of active and
sterile neutrinos are also presented. Finally, we give predictions for the
day-night asymmetry in the SNO experiment, for the event rate in the BOREXINO
and LowNu experiments, and discuss briefly the constraints on the solar
neutrino oscillation parameters which can be obtained with prospective KamLAND
data.Comment: Version to appear in PL
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