2,994 research outputs found
Anomalous Hall Effect of Calcium-doped Lanthanum Cobaltite Films
The Hall resistivity, magnetoresistance, and magnetization of
La_{1-x}Ca_{x}CoO_{3} epitaxial films with x between 0.25 and 0.4 grown on
lanthanum aluminate were measured in fields up to 7 T. The x=1/3 film, shows a
reentrant metal insulator transition. Below 100 K, the x=1/3 and 0.4 films have
significant coercivity which increases with decreasing temperature. At low
temperature the Hall resistivity remains large and essentially field
independent in these films, except for a sign change at the coercive field that
is more abrupt than the switching of the magnetization. A unique
magnetoresistance behavior accompanies this effect. These results are discussed
in terms of a percolation picture and the mixed spin state model for this
system. We propose that the low-temperature Hall effect is caused by
spin-polarized carriers scattering off of orbital disorder in the spin-ordered
clusters.Comment: REVTeX 4, 3 pages with 4 encapsulated postscript graphics. Submitted
to MMM 2002 conference proceedings (J. Appl. Phys.
Economic Policy Following the Terrorist Attacks
America has shown its best side in recent weeks in the efforts to help the victims of September 11. And it is showing its strength as it moves to strike back and tighten security at home. Dealing with the economic impact of these horrendous crimes has, appropriately, not been the first priority.
Contract Theory and the Moderation for Inflation by Recession and by Controls
macroeconomics, contract theory, inflation, recession
Productivity and the Services of Capital and Labor
macroeconomics, productivity, labor
The Productivity Growth Slowdown by Industry
macroeconomics, financial crisis, crises, U.S. markets, international markets
Refined Characterization of Student Perspectives on Quantum Physics
The perspectives of introductory classical physics students can often
negatively influence how those students later interpret quantum phenomena when
taking an introductory course in modern physics. A detailed exploration of
student perspectives on the interpretation of quantum physics is needed, both
to characterize student understanding of physics concepts, and to inform how we
might teach traditional content. Our previous investigations of student
perspectives on quantum physics have indicated they can be highly nuanced, and
may vary both within and across contexts. In order to better understand the
contextual and often seemingly contradictory stances of students on matters of
interpretation, we interviewed 19 students from four introductory modern
physics courses taught at the University of Colorado. We find that students
have attitudes and opinions that often parallel the stances of expert
physicists when arguing for their favored interpretations of quantum mechanics,
allowing for more nuanced characterizations of student perspectives in terms of
three key interpretive themes. We present a framework for characterizing
student perspectives on quantum mechanics, and demonstrate its utility in
interpreting the sometimes-contradictory nature of student responses to
previous surveys. We further find that students most often vacillate in their
responses when what makes intuitive sense to them is not in agreement with what
they consider to be a correct response, underscoring the need to distinguish
between the personal and the public perspectives of introductory modern physics
students.Comment: 24 pages, 31 references, 1 Appendix (5 pages
Teaching Quantum Interpretations: Revisiting the goals and practices of introductory quantum physics courses
Most introductory quantum physics instructors would agree that transitioning
students from classical to quantum thinking is an important learning goal, but
may disagree on whether or how this can be accomplished. Although (and perhaps
because) physicists have long debated the physical interpretation of quantum
theory, many instructors choose to avoid emphasizing interpretive themes; or
they discuss the views of scientists in their classrooms, but do not adequately
attend to student interpretations. In this synthesis and extension of prior
work, we demonstrate: (1) instructors vary in their approaches to teaching
interpretive themes; (2) different instructional approaches have differential
impacts on student thinking; and (3) when student interpretations go
unattended, they often develop their own (sometimes scientifically undesirable)
views. We introduce here a new modern physics curriculum that explicitly
attends to student interpretations, and provide evidence-based arguments that
doing so helps them to develop more consistent interpretations of quantum
phenomena, more sophisticated views of uncertainty, and greater interest in
quantum physics.Comment: 14 pages, 11 figures; submitted to PRST-PER: Focused Collection on
Upper-Division PER. arXiv admin note: text overlap with arXiv:1409.849
What Does International Experience Tell Us About Regulatory Consolidation?
Describes the integrated, twin peaks, functional, and institutional approaches to financial regulation and draws lessons from how Canada's, the United Kingdom's, Australia's, and other countries' regulatory structures have fared in the financial crisis
Interpretation in Quantum Physics as Hidden Curriculum
Prior research has demonstrated how the realist perspectives of classical
physics students can translate into specific beliefs about quantum phenomena
when taking an introductory modern physics course. Student beliefs regarding
the interpretation of quantum mechanics often vary by context, and are most
often in alignment with instructional goals in topic areas where instructors
are explicit in promoting a particular perspective. Moreover, students are more
likely to maintain realist perspectives in topic areas where instructors are
less explicit in addressing interpretive themes, thereby making such issues
part of a hidden curriculum. We discuss various approaches to addressing
student perspectives and interpretive themes in a modern physics course, and
explore the associated impacts on student thinking
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