100 research outputs found
What do we know about the Pedagogical Content Knowledge of History teachers: A review of empirical research
Teachers’ pedagogical content knowledge of two specific historical contexts captured and compared
PCK is seen as the transformation of content knowledge and pedagogical knowledge into a different type of knowledge that is used to develop and carry out teaching strategies. To gain more insight into the extent to which PCK is content specific, the PCK about more topics or concepts should be compared. However, researchers have rarely compared teachers’ concrete PCK about more than one topic. To examine the content dependency of PCK, we captured the PCK of sixteen experienced Dutch history teachers about two historical contexts (i.e. topics) using interviews and Content Representation questionnaires. Analysis reveals that all history teachers’ PCK about the two contexts overlaps, although the degree of overlap differs. Teachers with relatively more overlap are driven by their overarching subject related goals and less by the historical context they teach. We discuss the significance of these outcomes for the role of teaching orientation as a part of PCK
Plasma lens for US based super neutrino beam at either FNAL OR BNL
The plasma lens concept is examined as an alternative to focusing horns and
solenoids for a neutrino beam facility. The concept is based on a combined
high-current lens/target configuration. Current is fed at an electrode located
downstream from the beginning of the target where pion capturing is needed. The
current is carried by plasma outside the target. A second plasma lens section,
with an additional current feed, follows the target. The plasma is immersed in
a relatively small solenoidal magnetic field to facilitate its current profile
shaping to optimize pion capture. Simulations of the not yet fully optimized
configuration yielded a 25% higher neutrino flux at a detector situated at 3 km
from the target than the horn system for the entire energy spectrum and a
factor of 2.5 higher flux for neutrinos with energy larger than 3 GeV. A major
advantage of plasma lenses is in background reduction. In antineutrino
operation, neutrino background is reduced by a factor of close to 3 for the
whole spectrum, and for energy larger than 3 GeV, neutrino background is
reduced by a factor of 3.6. Plasma lenses have additional advantages: larger
axial currents, high signal purity: minimal neutrino background in antineutrino
runs. The lens medium consists of plasma, consequently, particle absorption and
scattering is negligible. Withstanding high mechanical and thermal stresses in
a plasma is not an issue.Comment: 4 pages, 4 figures submitted to Particle Accelerators Conference 2007
(PAC07
Long-term reliability of the phospholamban (PLN) p.(Arg14del) risk model in predicting major ventricular arrhythmia:a landmark study
Aims:Recently, a genetic variant-specific prediction model for phospholamban (PLN) p.(Arg14del)-positive individuals was developed to predict individual major ventricular arrhythmia (VA) risk to support decision-making for primary prevention implantable cardioverter defibrillator (ICD) implantation. This model predicts major VA risk from baseline data, but iterative evaluation of major VA risk may be warranted considering that the risk factors for major VA are progressive. Our aim is to evaluate the diagnostic performance of the PLN p.(Arg14del) risk model at 3-year follow-up. Methods:We performed a landmark analysis 3 years after presentation and selected only patients with no prior major VA. Data were and results collected of 268 PLN p.(Arg14del)-positive subjects, aged 43.5 ± 16.3 years, 38.9% male. After the 3 years landmark, subjects had a mean follow-up of 4.0 years (± 3.5 years) and 28 (10%) subjects experienced major VA with an annual event rate of 2.6% [95% confidence interval (CI) 1.6–3.6], defined as sustained VA, appropriate ICD intervention, or (aborted) sudden cardiac death. The PLN p.(Arg14del) risk score yielded good discrimination in the 3 years landmark cohort with a C-statistic of 0.83 (95% CI 0.79–0.87) and calibration slope of 0.97. Conclusion:The PLN p.(Arg14del) risk model has sustained good model performance up to 3 years follow-up in PLN p.(Arg14del)positive subjects with no history of major VA. It may therefore be used to support decision-making for primary prevention ICD implantation not merely at presentation but also up to at least 3 years of follow-up.</p
Long-term reliability of the phospholamban (PLN) p.(Arg14del) risk model in predicting major ventricular arrhythmia:a landmark study
Aims:Recently, a genetic variant-specific prediction model for phospholamban (PLN) p.(Arg14del)-positive individuals was developed to predict individual major ventricular arrhythmia (VA) risk to support decision-making for primary prevention implantable cardioverter defibrillator (ICD) implantation. This model predicts major VA risk from baseline data, but iterative evaluation of major VA risk may be warranted considering that the risk factors for major VA are progressive. Our aim is to evaluate the diagnostic performance of the PLN p.(Arg14del) risk model at 3-year follow-up. Methods:We performed a landmark analysis 3 years after presentation and selected only patients with no prior major VA. Data were and results collected of 268 PLN p.(Arg14del)-positive subjects, aged 43.5 ± 16.3 years, 38.9% male. After the 3 years landmark, subjects had a mean follow-up of 4.0 years (± 3.5 years) and 28 (10%) subjects experienced major VA with an annual event rate of 2.6% [95% confidence interval (CI) 1.6–3.6], defined as sustained VA, appropriate ICD intervention, or (aborted) sudden cardiac death. The PLN p.(Arg14del) risk score yielded good discrimination in the 3 years landmark cohort with a C-statistic of 0.83 (95% CI 0.79–0.87) and calibration slope of 0.97. Conclusion:The PLN p.(Arg14del) risk model has sustained good model performance up to 3 years follow-up in PLN p.(Arg14del)positive subjects with no history of major VA. It may therefore be used to support decision-making for primary prevention ICD implantation not merely at presentation but also up to at least 3 years of follow-up.</p
Disentangling the Evolution of Electrons and Holes in photoexcited ZnO nanoparticles
The evolution of charge carriers in photoexcited room temperature ZnO
nanoparticles in solution is investigated using ultrafast ultraviolet
photoluminescence spectroscopy, ultrafast Zn K-edge absorption spectroscopy and
ab-initio molecular dynamics (MD) simulations. The photoluminescence is excited
at 4.66 eV, well above the band edge, and shows that electron cooling in the
conduction band and exciton formation occur in <500 fs, in excellent agreement
with theoretical predictions. The X-ray absorption measurements, obtained upon
excitation close to the band edge at 3.49 eV, are sensitive to the migration
and trapping of holes. They reveal that the 2 ps transient largely reproduces
the previously reported transient obtained at 100 ps time delay in synchrotron
studies. In addition, the X-ray absorption signal is found to rise in ~1.4 ps,
which we attribute to the diffusion of holes through the lattice prior to their
trapping at singly-charged oxygen vacancies. Indeed, the MD simulations show
that impulsive trapping of holes induces an ultrafast expansion of the cage of
Zn atoms in <200 fs, followed by an oscillatory response at a frequency of ~100
cm-1, which corresponds to a phonon mode of the system involving the Zn
sub-lattice
Temporary and lasting effects of childhood deprivation on male stature. Late adolescent stature and catch-up growth in Woerden (The Netherlands) in the first half of the nineteenth century
Developing a ‘big picture’: Effects of collaborative construction of multimodal representations in history
Comparing the effects of representational tools in collaborative and individual inquiry learning
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