2,199 research outputs found
The Forgotten Subjects: Implementation of Science and Social Studies into Elementary Education
The content areas of science and social studies are areas that students in today\u27s elementary education classrooms do not interact with daily. In many general education classrooms, literacy and mathematics take up a majority of the instructional time leaving students missing out on important skills that help them grow and flourish in society. The importance of science and social studies within the classrooms goes beyond simple means of expanding their knowledge. For example, these forgotten subjects allow students to connect with the world around them and incorporate the higher levels of Bloom\u27s Taxonomy. The content areas are used to deepen students\u27 skills and boost their impact left on society. Articles, journals, and webpages from the Murray State University library database and other outlets were collected and analyzed. The purpose of this literature review is to examine both the presence and the impact of science and social studies within the classroom. This review has the potential to contribute to the field of education by giving teachers the opportunity to see the detrimental impacts due of the lack of science and social studies, providing benefits to support the inclusion of science and social studies, as well as suggesting recommendations that can be implemented to boost science and social studies content time. Within the literature, I will compare and contrast themes that emerge and potentially determine patterns between schools with or without these subjects to support the recommendation of science and social studies being implemented into everyday curricula
Order-disorder transition in nanoscopic semiconductor quantum rings
Using the path integral Monte Carlo technique we show that semiconductor
quantum rings with up to six electrons exhibit a temperature, ring diameter,
and particle number dependent transition between spin ordered and disordered
Wigner crystals. Due to the small number of particles the transition extends
over a broad temperature range and is clearly identifiable from the electron
pair correlation functions.Comment: 4 pages, 5 figures, For recent information on physics of small
systems see http://www.smallsystems.d
Energy levels and far-infrared spectroscopy for two electrons in a semiconductor nanoring
The effects of electron-electron interaction of a two-electron nanoring on
the energy levels and far-infrared (FIR) spectroscopy have been investigated
based on a model calculation which is performed within the exactly numerical
diagonalization. It is found that the interaction changes the energy spectra
dramatically, and also shows significant influence on the FIR spectroscopy. The
crossings between the lowest spin-singlet and triplet states induced by the
coulomb interaction are clearly revealed. Our results are related to the
experiment recently carried out by A. Lorke et al. [Phys. Rev. Lett. 84, 2223
(2000)].Comment: 17 pages, 6 figures, revised and accepted by Phys. Rev. B (Dec. 15
Optical Response of Grating-Coupler-Induced Intersubband Resonances: The Role of Wood's Anomalies
Grating-coupler-induced collective intersubband transitions in a
quasi-two-dimensional electron system are investigated both experimentally and
theoretically. Far-infrared transmission experiments are performed on samples
containing a quasi-two-dimensional electron gas quantum-confined in a parabolic
quantum well. For rectangular shaped grating couplers of different periods we
observe a strong dependence of the transmission line shape and peak height on
the period of the grating, i.e. on the wave vector transfer from the diffracted
beams to the collective intersubband resonance. It is shown that the line shape
transforms with increasing grating period from a Lorentzian into a strongly
asymmetric line shape. Theoretically, we treat the problem by using the
transfer-matrix method of local optics and apply the modal-expansion method to
calculate the influence of the grating. The optically uniaxial
quasi-two-dimensional electron gas is described in the long-wavelength limit of
the random-phase approximation by a local dielectric tensor, which includes
size quantization effects. Our theory reproduces excellently the experimental
line shapes. The deformation of the transmission line shapes we explain by the
occurrence of both types of Wood's anomalies.Comment: 28 pages, 7 figures. Physical Review B , in pres
Mean parameter model for the Pekar-Fr\"{o}hlich polaron in a multilayered heterostructure
The polaron energy and the effective mass are calculated for an electron
confined in a finite quantum well constructed of
layers. To simplify the study we suggest a model in which parameters of a
medium are averaged over the ground-state wave function. The rectangular and
the Rosen-Morse potential are used as examples.
To describe the confined electron properties explicitly to the second order
of perturbations in powers of the electron-phonon coupling constant we use the
exact energy-dependent Green function for the Rosen-Morse confining potential.
In the case of the rectangular potential, the sum over all intermediate virtual
states is calculated. The comparison is made with the often used leading term
approximation when only the ground-state is taken into account as a virtual
state. It is shown that the results are quite different, so the incorporation
of all virtual states and especially those of the continuous spectrum is
essential.
Our model reproduces the correct three-dimensional asymptotics at both small
and large widths. We obtained a rather monotonous behavior of the polaron
energy as a function of the confining potential width and found a peak of the
effective mass. The comparison is made with theoretical results by other
authors. We found that our model gives practically the same (or very close)
results as the explicit calculations for potential widths .Comment: 12 pages, LaTeX, including 5 PS-figures, subm. to Phys. Rev. B, new
data are discusse
Jahn-Teller stabilization of a "polar" metal oxide surface: Fe3O4(001)
Using ab initio thermodynamics we compile a phase diagram for the surface of
Fe3O4(001) as a function of temperature and oxygen pressures. A hitherto
ignored polar termination with octahedral iron and oxygen forming a wave-like
structure along the [110]-direction is identified as the lowest energy
configuration over a broad range of oxygen gas-phase conditions. This novel
geometry is confirmed in a x-ray diffraction analysis. The stabilization of the
Fe3O4(001)-surface goes together with dramatic changes in the electronic and
magnetic properties, e.g., a halfmetal-to-metal transition.Comment: 4 pages, 4 figure
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