Development and Validation of the Colorado Learning Attitudes about Science Survey for Experimental Physics

As part of a comprehensive effort to transform our undergraduate physics laboratories and evaluate the impacts of these efforts, we have developed the Colorado Learning Attitudes about Science Survey for Experimental Physics (E-CLASS). The E-CLASS assesses the changes in students' attitudes about a variety of scientific laboratory practices before and after a lab course and compares attitudes with perceptions of the course grading requirements and laboratory practices. The E-CLASS is designed to give researchers insight into students' attitudes and also to provide actionable evidence to instructors looking for feedback on their courses. We present the development, validation, and preliminary results from the initial implementation of the survey in three undergraduate physics lab courses.Comment: 8 pages, 4 figures, 1 table, submitted to 2012 PERC Proceeding

Development and results from a survey on students views of experiments in lab classes and research

The Colorado Learning Attitudes about Science Survey for Experimental Physics (E-CLASS) was developed as a broadly applicable assessment tool for undergraduate physics lab courses. At the beginning and end of the semester, the E-CLASS assesses students views about their strategies, habits of mind, and attitudes when doing experiments in lab classes. Students also reflect on how those same strategies, habits-of-mind, and attitudes are practiced by professional researchers. Finally, at the end of the semester, students reflect on how their own course valued those practices in terms of earning a good grade. In response to frequent calls to transform laboratory curricula to more closely align it with the skills and abilities needed for professional research, the E-CLASS is a tool to assess students' perceptions of the gap between classroom laboratory instruction and professional research. The E-CLASS has been validated and administered in all levels of undergraduate physics classes. To aid in its use as a formative assessment tool, E-CLASS provides all participating instructors with a detailed feedback report. Example figures and analysis from the report are presented to demonstrate the capabilities of the E-CLASS. The E-CLASS is actively administered through an online interface and all interested instructors are invited to administer the E-CLASS their own classes and will be provided with a summary of results at the end of the semester

A numerical finite size scaling approach to many-body localization

We develop a numerical technique to study Anderson localization in interacting electronic systems. The ground state of the disordered system is calculated with quantum Monte-Carlo simulations while the localization properties are extracted from the ``Thouless conductance'' $g$, i.e. the curvature of the energy with respect to an Aharonov-Bohm flux. We apply our method to polarized electrons in a two dimensional system of size $L$. We recover the well known universal $\beta(g)=\rm{d}\log g/\rm{d}\log L$ one parameter scaling function without interaction. Upon switching on the interaction, we find that $\beta(g)$ is unchanged while the system flows toward the insulating limit. We conclude that polarized electrons in two dimensions stay in an insulating state in the presence of weak to moderate electron-electron correlations.Comment: 5 pages, 4 figure

An epistemology and expectations survey about experimental physics: Development and initial results

In response to national calls to better align physics laboratory courses with the way physicists engage in research, we have developed an epistemology and expectations survey to assess how students perceive the nature of physics experiments in the contexts of laboratory courses and the professional research laboratory. The Colorado Learning Attitudes about Science Survey for Experimental Physics (E-CLASS) evaluates students' epistemology at the beginning and end of a semester. Students respond to paired questions about how they personally perceive doing experiments in laboratory courses and how they perceive an experimental physicist might respond regarding their research. Also, at the end of the semester, the E-CLASS assesses a third dimension of laboratory instruction, students' reflections on their course's expectations for earning a good grade. By basing survey statements on widely embraced learning goals and common critiques of teaching labs, the E-CLASS serves as an assessment tool for lab courses across the undergraduate curriculum and as a tool for physics education research. We present the development, evidence of validation, and initial formative assessment results from a sample that includes 45 classes at 20 institutions. We also discuss feedback from instructors and reflect on the challenges of large-scale online administration and distribution of results.Comment: 31 pages, 9 figures, 3 tables, submitted to Phys. Rev. - PE

Derivation of the Quantum Probability Rule without the Frequency Operator

We present an alternative frequencists' proof of the quantum probability rule which does not make use of the frequency operator, with expectation that this can circumvent the recent criticism against the previous proofs which use it. We also argue that avoiding the frequency operator is not only for technical merits for doing so but is closely related to what quantum mechanics is all about from the viewpoint of many-world interpretation.Comment: 12 page

Four-Probe Measurements of Carbon Nanotubes with Narrow Metal Contacts

We find that electrons in single-wall carbon nanotubes may propagate substantial distances (tens of nanometers) under the metal contacts. We perform four-probe transport measurements of the nanotube conductance and observe significant deviations from the standard Kirchhoff's circuit rules. Most noticeably, injecting current between two neighboring contacts on one end of the nanotube, induces a non-zero voltage difference between two contacts on the other end.Comment: 4 pages, 5 figures; submitte

Quantum Probability from Decision Theory?

In a recent paper (quant-ph/9906015), Deutsch claims to derive the "probabilistic predictions of quantum theory" from the "non-probabilistic axioms of quantum theory" and the "non-probabilistic part of classical decision theory." We show that his derivation fails because it includes hidden probabilistic assumptions.Comment: LaTeX, 8 pages, no figure

New constraints on dust emission and UV attenuation of z=6.5-7.5 galaxies from millimeter observations

We have targeted two recently discovered Lyman break galaxies (LBGs) to search for dust continuum and [CII] 158 micron line emission. The strongly lensed z~6.8 LBG A1703-zD1 behind the galaxy cluster Abell 1703, and the spectroscopically confirmed z=7.508 LBG z8-GND-5296 in the GOODS-N field have been observed with the Plateau de Bure interferometer (PdBI) at 1.2mm. These observations have been combined with those of three z>6.5 Lya emitters (named HCM6A, Himiko, and IOK-1), for which deep measurements were recently obtained with the PdBI and ALMA. [CII] is undetected in both galaxies, providing a deep upper limit for Abell1703-zD1, comparable to recent ALMA non-detections. Dust continuum emission from Abell1703-zD1 and z8-GND-5296 is not detected with an rms of 0.12 and 0.16 mJy/beam. From these non-detections we derive upper limits on their IR luminosity and star formation rate, dust mass, and UV attenuation. Thanks to strong gravitational lensing the limit for Abell1703-zD1 is probing the sub-LIRG regime ($L_{IR} <8.1 \times 10^{10}$ Lsun) and very low dust masses ($M_d<1.6 \times 10^7$ Msun). We find that all five galaxies are compatible with the Calzetti IRX-$\beta$ relation, their UV attenuation is compatible with several indirect estimates from other methods (the UV slope, extrapolation of the attenuation measured from the IR/UV ratio at lower redshift, and SED fits), and the dust-to-stellar mass ratio is not incompatible with that of galaxies from z=0 to 3. For their stellar mass the high-z galaxies studied here have an attenuation below the one expected from the mean relation of low redshift (z<1.5) galaxies. More and deeper (sub)-mm data are clearly needed to directly determine the UV attenuation and dust content of the dominant population of high-z star-forming galaxies and to establish more firmly their dependence on stellar mass, redshift, and other properties.Comment: 10 pages, 7 figures. Minor revisions. Accepted for publication in A&