Dominant ferromagnetism in the spin-1/2 half-twist ladder 334 compounds, Ba3Cu3In4O12 and Ba3Cu3Sc4O12

The magnetic properties of polycrystalline samples of Ba3Cu3In4O12 (In-334) and Ba3Cu3Sc4O12 (Sc-334) are reported. Both 334 phases have a structure derived from perovskite, with CuO4 squares interconnected to form half-twist ladders along the c-axis. The Cu-O-Cu angles, ~ 90o, and the positive Weiss temperatures indicate the presence of significant ferromagnetic (FM) interactions along the Cu ladders. At low temperatures, T < 20 K, sharp transitions in the magnetic susceptibility and heat capacity measurements indicate three-dimensional (3D) antiferromagnetic (AFM) ordering at TN. TN is suppressed on application of a field and a complex magnetic phase diagram with three distinct magnetic regimes below the upper critical field can be inferred from our measurements. The magnetic interactions are discussed in relation to a modified spin-1/2 FM-AFM model and the 334 half-twist ladder is compared to other 2-rung ladder spin-1/2 systems.Comment: 20 pages, 7 figure

Evaluating the Chinese Revised Controlling Behaviors Scale (C-CBS-R)

The present study evaluated the utility of the Chinese version of the Revised Controlling Behaviors Scale (C-CBS-R) as a measure of controlling behaviors in violent Chinese intimate relationships. Using a mixed-methods approach, in-depth, individual interviews were conducted with 200 Chinese women survivors to elicit qualitative data about their personal experiences of control in intimate relationships. The use of controlling behaviors was also assessed using the C-CBS-R. Interview accounts suggested that the experiences of 91 of the women were consistent with the description of coercive control according to Dutton and Goodman’s (2005) conceptualization of coercion. Using the split-half validation procedure, a receiver operating characteristics (ROC) curve analysis was conducted with the first half of the sample. The area under the curve (AUC) for using the C-CBS-R to identify high control was .99, and the cutoff score of 1.145 maximized both sensitivity and specificity. Applying the cutoff score to the second half gave a sensitivity of 96% and a specificity of 95%. Overall, the C-CBS-R has demonstrated utility as a measure of controlling behaviors with a cutoff score for distinguishing high from low levels of control in violent Chinese intimate relationships

MICROTUBULE PROTEIN : Identification in and Transport to Nerve Endings

The subunit protein of microtubules, tubulin, has been demonstrated to be present in isolated nerve endings by gel electrophoresis, amino acid composition, and peptide mapping. The tubulin constitutes approximately 28% of the soluble protein of the nerve endings. The transport of tubulin to the nerve endings has been demonstrated and its relationship to slow transport is discussed

Galaxy Masses

Galaxy masses play a fundamental role in our understanding of structure formation models. This review addresses the variety and reliability of mass estimators that pertain to stars, gas, and dark matter. The different sections on masses from stellar populations, dynamical masses of gas-rich and gas-poor galaxies, with some attention paid to our Milky Way, and masses from weak and strong lensing methods, all provide review material on galaxy masses in a self-consistent manner.Comment: 145 pages, 28 figures, to appear in Reviews of Modern Physics. Figure 22 is missing here, and Figs. 15, 26-28 are at low resolution. This version has a slightly different title and some typos fixed in Chapter 5. For the full review with figures, please consult: http://www.astro.queensu.ca/~courteau/GalaxyMasses_28apr2014.pd

Robust Chauvenet Outlier Rejection

Sigma clipping is commonly used in astronomy for outlier rejection, but the number of standard deviations beyond which one should clip data from a sample ultimately depends on the size of the sample. Chauvenet rejection is one of the oldest, and simplest, ways to account for this, but, like sigma clipping, depends on the sample's mean and standard deviation, neither of which are robust quantities: Both are easily contaminated by the very outliers they are being used to reject. Many, more robust measures of central tendency, and of sample deviation, exist, but each has a tradeoff with precision. Here, we demonstrate that outlier rejection can be both very robust and very precise if decreasingly robust but increasingly precise techniques are applied in sequence. To this end, we present a variation on Chauvenet rejection that we call "robust" Chauvenet rejection (RCR), which uses three decreasingly robust/increasingly precise measures of central tendency, and four decreasingly robust/increasingly precise measures of sample deviation. We show this sequential approach to be very effective for a wide variety of contaminant types, even when a significant -- even dominant -- fraction of the sample is contaminated, and especially when the contaminants are strong. Furthermore, we have developed a bulk-rejection variant, to significantly decrease computing times, and RCR can be applied both to weighted data, and when fitting parameterized models to data. We present aperture photometry in a contaminated, crowded field as an example. RCR may be used by anyone at https://skynet.unc.edu/rcr, and source code is available there as well.Comment: 62 pages, 48 figures, 7 tables, accepted for publication in ApJ

Life test, 8000-hour, of an electron bombardment mercury ion thruster system for SERT 2 Final report

Operational performance of electron bombardment mercury ion thruster system during life testing in space simulation for SERT

Displaced but not replaced: the impact of e-learning on academic identities in higher education.

Challenges facing universities are leading many to implement institutional strategies to incorporate e-learning rather than leaving its adoption up to enthusiastic individuals. Although there is growing understanding about the impact of e-learning on the student experience, there is less understanding of academics’ perceptions of e-learning and its impact on their identities. This paper explores the changing nature of academic identities revealed through case study research into the implementation of e-learning at one UK university. By providing insight into the lived experiences of academics in a university in which technology is not only transforming access to knowledge but also influencing the balance of power between academic and student in knowledge production and use, it is suggested that academics may experience a jolt to their ‘trajectory of self’ when engaging with e-learning. The potential for e-learning to prompt loss of teacher presence and displacement as knowledge expert may appear to undermine the ontological security of their academic identity

Towards a first principles description of phonons in Ni50_{50}Pt50_{50} disordered alloys: the role of relaxation

Using a combination of density-functional perturbation theory and the itinerant coherent potential approximation, we study the effects of atomic relaxation on the inelastic incoherent neutron scattering cross sections of disordered Ni$_{50}$Pt$_{50}$ alloys. We build on previous work, where empirical force constants were adjusted {\it ad hoc} to agree with experiment. After first relaxing all structural parameters within the local-density approximation for ordered NiPt compounds, density-functional perturbation theory is then used to compute phonon spectra, densities of states, and the force constants. The resulting nearest-neighbor force constants are first compared to those of other ordered structures of different stoichiometry, and then used to generate the inelastic scattering cross sections within the itinerant coherent potential approximation. We find that structural relaxation substantially affects the computed force constants and resulting inelastic cross sections, and that the effect is much more pronounced in random alloys than in ordered alloys.Comment: 8 pages, 3 eps figures, uses revtex