4,789 research outputs found
Dynamic Models of Learning and Education Measurement
Pre-post testing is a commonly used method in physics education community for
evaluating students' achievement and or the effectiveness of teaching through a
specific period of instruction. A popular method to analyze pre-post testing
results is the normalized gain first brought to the physics education community
in wide use by R.R. Hake. This paper presents a measurement based probabilistic
model of the dynamic process of learning that explains the experimentally
observed features of the normalized gain. In Hake's study with thousands of
students' pre-post testing results, he observed that on average 48 courses
employing "interactive engagement" types of instruction achieved average
normalized gains about two standard deviations greater than did 14 courses
subjected to traditional instruction. For all courses the average normalized
gains had a very low correlation +0.02 with average pretest scores. This
feature of the normalized gain has allowed researchers to investigate the
effectiveness of instruction using data collected from classes with widely
different average pretest scores. However, the question of why the average
normalized gain has this feature and to what extent this feature is generally
present is not well understood. In addition, there have been debates as to what
the normalized gain actually measures, and concerns that it lacks a probability
framework that undergirds psychometric methods such as Item Response Theory
(IRT). The present model leads to an explanation of the observed features of
the normalized gain, connects to other models such as IRT, and shows that the
normalized gain does have a probability framework but one different from that
emphasized by IRT.Comment: Theoretical Models of Education Measuremen
Student Resources in Quantum Mechanics, or Why Students Need Meta-resources
We are trying to identify resources students are using to reason in quantum
mechanics. In this process we realize students must have not only the right
resources available but sophisticated for evaluating and controlling their
thought processes. We will discuss examples from student interviews to
illustrate our point.Comment: 4 pages, No figures, Submitted to the Physics Education Research
Conference Proceedings, 200
Flexibility of nucleic acids: from DNA to RNA
The structural flexibility of nucleic acids plays a key role in many
fundamental life processes, such as gene replication and expression,
DNA-protein recognition, and gene regulation. To obtain a thorough
understanding of nucleic acid flexibility, extensive studies have been
performed using various experimental methods and theoretical models. In this
review, we will introduce the progress that has been made in understanding the
flexibility of nucleic acids including DNAs and RNAs, and will emphasize the
experimental findings and the effects of salt, temperature, and sequence.
Finally, we will discuss the major unanswered questions in understanding the
flexibility of nucleic acids.Comment: 24 pages, 3 table
Global solutions and exterior Dirichlet problem for Monge-Ampere equation in
Monge-Amp\`ere equation in two dimensional spaces is different
in nature from their counterparts in higher dimensional spaces. In this article
we employ new ideas to establish two main results for the Monge-Amp\`ere
equation defined either globally in or outside a convex set.
First we prove the existence of a global solution that satisfies a prescribed
asymptotic behavior at infinity, if is asymptotically close to a positive
constant. Then we solve the exterior Dirichlet problem if data are given on the
boundary of a convex set and at infinity.Comment: 17 page
In-medium properties of kaons in a chiral approach
The first order self-energy corrections of the kaon in the symmetric nuclear
matter are calculated from kaon-nucleon scattering matrix elements using a
chiral Lagrangian within the framework of relativistic mean field
approximation. It shows that the effective mass and the potential of K^+ meson
are identical with those of K^- meson in the nuclear matter, respectively. The
effective mass of the kaon in the nuclear matter decreases with the nuclear
density increasing, and is not relevant to the kaon-nucleon Sigma term. The
kaon-nucleus potential is positive and increases with the nuclear density.
Moreover, the influence of the resonance on the -nucleus
potential due to the re-scattering term is discussed. Our results indicate the
K^- meson could not be bound in the nuclei even if the contribution of
resonance is considered.Comment: 8 pages, 3 figures, The contribution of Lambda(1405) resonance in the
rescattering process to the K-nucleus potential is discussed in the revised
versio
Full-Color Computational Imaging with Single-Pixel Detectors Based on a 2D Discrete Cosine Transform
We propose and demonstrate a computational imaging technique that uses
structured illumination based on a two-dimensional discrete cosine transform to
perform imaging with a single-pixel detector. A scene is illuminated by a
projector with two sets of orthogonal patterns, then by applying an inverse
cosine transform to the spectra obtained from the single-pixel detector a
full-color image is retrieved. This technique can retrieve an image from
sub-Nyquist measurements, and the background noise is easily canceled to give
excellent image quality. Moreover, the experimental setup is very simple.Comment: 7 pages,4 figure
Nonadiabatic noncyclic geometric quantum computation in Rydberg atoms
Nonadiabatic geometric quantum computation (NGQC) has been developed to
realize fast and robust geometric gate. However, the conventional NGQC is that
all of the gates are performed with exactly the sameamount of time, whether the
geometric rotation angle is large or small, due to the limitation of cyclic
condition. Here, we propose an unconventional scheme, called nonadiabatic
noncyclic geometric quantum computation(NNGQC), that arbitrary single- and
two-qubit geometric gate can be constructed via noncyclic non-Abeliangeometric
phase. Consequently, this scheme makes it possible to accelerate the
implemented geometric gatesagainst the effects from the environmental
decoherence. Furthermore, this extensible scheme can be applied invarious
quantum platforms, such as superconducting qubit and Rydberg atoms.
Specifically, for single-qubit gate,we make simulations with practical
parameters in neutral atom system to show the robustness of NNGQC and also
compare with NGQC using the recent experimental parameters to show that the
NNGQC can significantly suppress the decoherence error. In addition, we also
demonstrate that nontrivial two-qubit geometric gate can berealized via
unconventional Rydberg blockade regime within current experimental
technologies. Therefore, ourscheme provides a promising way for fast and robust
neutral-atom-based quantum computation.Comment: 6 pages, 6 figures. Published visio
A Modified Smoothed Particle Hydrodynamics Approach for Modelling Dynamic Contact Angle Hysteresis
Dynamic wetting plays an important role in the physics of multiphase flow,
and has significant influence on many industrial and geotechnical applications.
In this work, a modified smoothed particle hydrodynamics (SPH) model is
employed to simulate surface tension, contact angle, and dynamic wetting
effects. The wetting and dewetting phenomena are simulated in a capillary tube,
where the liquid particles are raised or withdrawn by a shifting substrate. The
SPH model is modified by introducing a newly-developed viscous force
formulation at liquid-solid interface to reproduce the rate-dependent behaviour
of moving contact line. Dynamic contact angle simulations with interfacial
viscous force are conducted to verify the effectiveness and accuracy of this
new formulation. In addition, the influence of interfacial viscous force with
different magnitude on contact angle dynamics is examined by empirical power
law correlations, and the derived constants suggest the dynamic contact angle
changes monotonically with interfacial viscous force. The simulation results
are consistent with the experimental observations and theoretical predictions,
implying that the interfacial viscous force can be associated with slip length
of flow and microscopic surface roughness. This work has demonstrated that the
modified SPH model can successfully account for the rate-dependent effects of
moving contact line, and can be used for realistic multiphase flow simulation
under dynamic conditions.Comment: 23 pages, 13 figure
Affective Factors in STEM Learning and Scientific Inquiry: Assessment of Cognitive Conflict and Anxiety
Cognitive conflict is well recognized as an important factor in conceptual
change and is widely used in developing inquiry-based curricula. However,
cognitive conflict can also contribute to student anxiety during learning,
which can have both positive and negative impacts on students' motivation and
learning achievement. Therefore, instructors need to be informed of the impacts
of introducing cognitive conflicts during teaching. To get this information,
teachers need a practical instrument that can help them identify the existence
and features of cognitive conflict introduced by the instruction and the
resulting anxiety. Based on the literature on studies of cognitive conflict and
student anxiety, a quantitative instrument, the In-class Conflict and Anxiety
Recognition Evaluation (iCARE), was developed and used to monitor the status of
students' cognitive conflict and anxiety in the Physics by Inquiry (PBI)
classes. This paper introduces this instrument and discusses the types of
information that can be measured. Research and pedagogical values of this
instrument are also discussed.Comment: 52 page
Analyzing Force Concept Inventory with Item Response Theory
Item Response Theory (IRT) is a popular assessment method used in education
measurement, which builds on an assumption of a probability framework
connecting students' innate ability and their actual performances on test
items. The model transforms students' raw test scores through a nonlinear
regression process into a scaled proficiency rating, which can be used to
compare results obtained with different test questions. IRT also provides a
theoretical approach to address ceiling effect and guessing. We applied IRT to
analyze the Force Concept Inventory (FCI). The data was collected from 2802
students taking intro level mechanics courses at The Ohio State University. The
data was analyzed with a 3-parameter item response model for multiple choice
questions. We describe the procedures of the analysis and discuss the results
and the interpretations. The analysis outcomes are compiled to provide a
detailed IRT measurement metric of the FCI, which can be easily referenced and
used by teachers and researchers for a range of assessment applications.Comment: 18 pages, 5 figure
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