Gains from the upgrade of the cold neutron triple-axis spectrometer FLEXX at the BER-II reactor

The upgrade of the cold neutron triple-axis spectrometer FLEXX is described. We discuss the characterisation of the gains from the new primary spectrometer, including a larger guide and double focussing monochromator, and present measurements of the energy and momentum resolution and of the neutron flux of the instrument. We found an order of magnitude gain in intensity (at the cost of coarser momentum resolution), and that the incoherent elastic energy widths are measurably narrower than before the upgrade. The much improved count rate should allow the use of smaller single crystals samples and thus enable the upgraded FLEXX spectrometer to continue making leading edge measurements.Comment: 8 pages, 7 figures, 5 table

Making Dioramas of Women Scientists Help Elementary Students Recognize Their Contributions

The STEM movement encourages girls to consider careers in science; however, for success, common misconceptions and biases need to be dispelled, while females’ spatial thinking skills are developed. All students, both girls and boys, need exposure to the accomplishments of women scientists to appreciate their contributions and to envision females as successful scientists. This one-week study conducted during a summer day camp examined upper elementary student (n = 15; 7 females, 8 males) attitudes toward science, women in science, and the possibility of a science career before and after participation in learning about diverse accomplished women scientists and making a diorama showcasing the professional work and caring actions of one of the scientists. The efficacy of this project for upper elementary students, conducted during a summer day camp, is supported by pretest-posttest data and attitude surveys. The five-day class showed positive changes in student plans for a career in science and improved attitudes toward the importance of females becoming scientists. Directions for constructing dioramas, examples of student-made work, and creative scenes made with given craft items are provided

Structural Fluctuations in the Spin Liquid State of Tb2Ti2O7

High resolution X-ray scattering measurements on single crystal Tb2Ti2O7 reveal finite structural correlations at low temperatures. This geometrically frustrated pyrochlore is known to exhibit a spin liquid, or cooperative paramagnetic state, at temperatures below ~ 20 K. Parametric studies of structural Bragg peaks appropriate to the Fd$\bar{3}$m space group of Tb2Ti2O7 reveal substantial broadening and peak intensity reduction in the temperature regime 20 K to 300 mK. We also observe a small, anomalous lattice expansion on cooling below a density maximum at ~ 18 K. These measurements are consistent with the development of fluctuations above a cooperative Jahn-Teller, cubic-tetragonal phase transition at very low temperatures.Comment: 5 pages, 4 figures, submitted for publicatio

Asymmetric Thermal Lineshape Broadening in a Gapped 3-Dimensional Antiferromagnet - Evidence for Strong Correlations at Finite Temperature

It is widely believed that magnetic excitations become increasingly incoherent as temperature is raised due to random collisions which limit their lifetime. This picture is based on spin-wave calculations for gapless magnets in 2 and 3 dimensions and is observed experimentally as a symmetric Lorentzian broadening in energy. Here, we investigate a three-dimensional dimer antiferromagnet and find unexpectedly that the broadening is asymmetric - indicating that far from thermal decoherence, the excitations behave collectively like a strongly correlated gas. This result suggests that a temperature activated coherent state of quasi-particles is not confined to special cases like the highly dimerized spin-1/2 chain but is found generally in dimerized antiferromagnets of all dimensionalities and perhaps gapped magnets in general

Enhancing Iowa High School Students\u27 Transition to College

We present our studies of the transitions of Iowa science students from high school to post-secondary colleges. Our report summarizes information and impressions from dealing with thousands of new students arriving at our six colleges, along with meetings and discussions with high school science teachers to add their viewpoints into our considerations. Feedback from community college, four year college, and high school science teachers highlighted the following five study issues and needs for improving student transitions from high school to college science: 1) Better math preparation is needed; 2) More work with inquiry-based learning rather than with facts and memorization is needed in both secondary and post-secondary courses; 3) Students must become aware of career choices earlier; 4) Misconceptions by teachers at both levels must be minimized; and 5) High school and college science educators must improve intercommunication. To address these issues differently, our team invited Nobel Laureate Leon Lederman to be keynote speaker at the Iowa Science Teachers Fall Conference in October 2004. Dr. Lederman has campaigned for revamping the high school curriculum to have mathematics and the sciences integrated into a coherent, logical, interconnected whole, with conceptual physics first, to enable students to learn with a minimum of memorization. Feedback from high school science teachers has been very positive. Several Iowa high schools expressed interest in adopting this approach, and one Iowa high school has incorporated, at submission time, this innovation into their high school curriculum

Teacher-made Tactile Science Materials with Critical and Creative Thinking Activities for Learners Including those with Visual Impairments

Gifted students with visual impairments are twice exceptional learners and may not evidence their advanced science aptitudes without appropriate accommodations for learning science. However, effective tactile science teaching materials may be easily made. Recent research has shown that when tactile materials are used with all students in the class, everyone benefits. This presentation provides many classroom-tested example sets of tactile materials for teaching upper elementary and middle school science concepts. These science concepts include the parts of: a flower, ear, insect, beaver habitat, volcano, hydroelectric power plant, plant cell, and sun. Critical and creative thinking skill strategies to accompany these materials for further developing gifted students’ science knowledge also are provided. These include application of the Edward de Bono CoRT Breadth thinking skills and other creative thinking skills, such as making a model or using analogy. This document represents the content of a gifted education conference presentation made at the Iowa Talented and Gifted Association Annual Meeting

A Limousin Specific Myostatin Allele Affects Longissimus Muscle Area and Fatty Acid Profiles in a Wagyu-Limousin F2 Population

A microsatellite-based genome scan of a Wagyu x Limousin F(2) cross population previously demonstrated QTL affecting LM area and fatty acid composition were present in regions near the centromere of BTA2. In this study, we used 70 SNP markers to examine the centromeric 24 megabases (Mb) of BTA2, including the Limousin-specific F94L myostatin allele (AB076403.1; 415C \u3e A) located at approximately 6 Mb on the draft genome sequence of BTA2. A significant effect of the F94L marker was observed (F = 60.17) for LM area, which indicated that myostatin is most likely responsible for the effect. This is consistent with previous reports that the substitution of Leu for Phe at AA 94 of myostatin (caused by the 415C \u3e A transversion) is associated with increased muscle growth. Surprisingly, several fatty acid trait QTL, which affected the amount of unsaturated fats, also mapped to or very near the myostatin marker, including the ratio of C16:1 MUFA to C16:0 saturated fat (F = 16.72), C18:1 to C18:0 (F = 18.88), and total content of MUFA (F = 17.12). In addition, QTL for extent of marbling (F = 14.73) approached significance (P = 0.05), and CLA concentration (F = 9.22) was marginally significant (P = 0.18). We also observed associations of SNP located at 16.3 Mb with KPH (F = 15.00) and for the amount of SFA (F = 12.01). These results provide insight into genetic differences between the Wagyu and Limousin breeds and may lead to a better tasting and healthier product for consumers through improved selection for lipid content of beef

Neutron and X-ray Scattering Studies of the Lightly-Doped Spin-Peierls System Cu(1-x)Cd(x)GeO3

Single crystals of the lightly-doped spin-Peierls system Cu(1-x)Cd(x)GeO3 have been studied using bulk susceptibility, x-ray diffraction, and inelastic neutron scattering techniques. We investigate the triplet gap in the magnetic excitation spectrum of this quasi-one dimensional quantum antiferromagnet, and its relation to the spin-Peierls dimerisation order parameter. We employ two different theoretical forms to model the inelastic neutron scattering cross section and chi''(Q,omega), and show the sensitivity of the gap energy to the choice of chi''(Q,omega). We find that a finite gap exists at the spin-Peierls phase transition.Comment: 15 Pages, 7 Figures, Submitted to J. Phys. :Condensed Matte

Magnetic properties of the quantum spin-1/2 XX diamond chain: The Jordan-Wigner approach

The Jordan-Wigner transformation is applied to study magnetic properties of the quantum spin-1/2 $XX$ model on the diamond chain. Generally, the Hamiltonian of this quantum spin system can be represented in terms of spinless fermions in the presence of a gauge field and different gauge-invariant ways of assigning the spin-fermion transformation are considered. Additionally, we analyze general properties of a free-fermion chain, where all gauge terms are neglected and discuss their relevance for the quantum spin system. A consideration of interaction terms in the fermionic Hamiltonian rests upon the Hartree-Fock procedure after fixing the appropriate gauge. Finally, we discuss the magnetic properties of this quantum spin model at zero as well as non-zero temperatures and analyze the validity of the approximation used through a comparison with the results of the exact diagonalization method for finite (up to 36 spins) chains. Besides the $m=1/3$ plateau the most prominent feature of the magnetization curve is a jump at intermediate field present for certain values of the frustrating vertical bond.Comment: 12 pages, 9 figures, accepted for publication in Eur. Phys. J.