Students Watching Stars Evolve

We describe a study of period changes in 59 RR Lyrae stars, using times of maximum brightness from the GEOS database. The work was carried out by outstanding senior high school students in the University of Toronto Mentorship Program. This paper is written in such a way that high school or undergraduate physics and astronomy students could use it as a guide and template for carrying out original research, by studying period changes in these and other types of variable stars

Beyond Product State Approximations for a Quantum Analogue of Max Cut

We consider a computational problem where the goal is to approximate the maximum eigenvalue of a two-local Hamiltonian that describes Heisenberg interactions between qubits located at the vertices of a graph. Previous work has shed light on this problem's approximability by product states. For any instance of this problem the maximum energy attained by a product state is lower bounded by the Max Cut of the graph and upper bounded by the standard Goemans-Williamson semidefinite programming relaxation of it. Gharibian and Parekh described an efficient classical approximation algorithm for this problem which outputs a product state with energy at least 0.498 times the maximum eigenvalue in the worst case, and observe that there exist instances where the best product state has energy 1/2 of optimal. We investigate approximation algorithms with performance exceeding this limitation which are based on optimizing over tensor products of few-qubit states and shallow quantum circuits. We provide an efficient classical algorithm which achieves an approximation ratio of at least 0.53 in the worst case. We also show that for any instance defined by a 3- or 4-regular graph, there is an efficiently computable shallow quantum circuit that prepares a state with energy larger than the best product state (larger even than its semidefinite programming relaxation)

Mindfulness Skills and Retention Risk in First-Generation Undergraduate Students

First-generation college students experience more negative emotional states and higher stress levels than their continuing generation peers, take approximately two years longer to complete undergraduate degree programs, and are less than one percent likely to re-enroll in college. Mindfulness skills have been reported to alleviate anxiety and stress, improve adjustment to college, and improve academic performance, but a gap in the literature existed specific to first-generation college students. Guided by the theory of planned behavior and the monitor and acceptance theory, the purpose of this quantitative study was to examine the relationship between trait mindfulness skills and retention risk in 221 first-generation undergraduate students. Multiple linear regressions were conducted to determine the combined and relative effects of subscale scores of the Five Facet Mindfulness Questionnaire—Short Form (FFMQ-SF) in accounting for variance in each of four subscales of the Theory of Planned Behavior on Student Retention in College Scale (TPBSRCS). The five FFMQ-SF subscale scores best predicted variance in self-efficacy towards course and were least effective in accounting for variance in norms about course completion. As indexed by Johnson’s ε relative weight, the FFMQ-SF observe and nonreact subscale scores were the most important predictors, on average, across all four TPBSRCS subscale models. Specific to TPBSRCS intention to withdraw, FFMQ-SF actaware and describe subscale scores were most important. In general, significant relationships were found between trait mindfulness skills and retention risks that could inform institutional mindfulness programs to address retention risk in first-generation students leading to positive social change

Mindfulness Skills and Retention Risk in First-Generation Undergraduate Students

First-generation college students experience more negative emotional states and higher stress levels than their continuing generation peers, take approximately two years longer to complete undergraduate degree programs, and are less than one percent likely to re-enroll in college. Mindfulness skills have been reported to alleviate anxiety and stress, improve adjustment to college, and improve academic performance, but a gap in the literature existed specific to first-generation college students. Guided by the theory of planned behavior and the monitor and acceptance theory, the purpose of this quantitative study was to examine the relationship between trait mindfulness skills and retention risk in 221 first-generation undergraduate students. Multiple linear regressions were conducted to determine the combined and relative effects of subscale scores of the Five Facet Mindfulness Questionnaire—Short Form (FFMQ-SF) in accounting for variance in each of four subscales of the Theory of Planned Behavior on Student Retention in College Scale (TPBSRCS). The five FFMQ-SF subscale scores best predicted variance in self-efficacy towards course and were least effective in accounting for variance in norms about course completion. As indexed by Johnson’s ε relative weight, the FFMQ-SF observe and nonreact subscale scores were the most important predictors, on average, across all four TPBSRCS subscale models. Specific to TPBSRCS intention to withdraw, FFMQ-SF actaware and describe subscale scores were most important. In general, significant relationships were found between trait mindfulness skills and retention risks that could inform institutional mindfulness programs to address retention risk in first-generation students leading to positive social change

Selection of Environmentally Friendly Solvents for the Extravehicular Mobility Unit Secondary Oxygen Pack Cold Trap Testing

Freon-113(TradeMark) has been used as a chemistry lab sampling solvent at NASA/JSC for EMU (extravehicular Mobility Unit) SOP (Secondary Oxygen Pack) oxygen testing Cold Traps utilized at the USA (United Space Alliance) Houston facility. Similar testing has occurred at the HSWL (Hamilton Sundstrand Windsor Locks) facility. A NASA Executive Order bans the procurement of all ODS (ozone depleting substances), including Freon-113 by the end of 2009. In order to comply with NASA direction, HSWL began evaluating viable solvents to replace Freon-113 . The study and testing effort to find Freon-113 replacements used for Cold Trap sampling is the subject of this paper. Test results have shown HFE-7100 (a 3M fluorinated ether) to be an adequate replacement for Freon-113 as a solvent to remove and measure the non-volatile residue collected in a Cold Trap during oxygen testing. Furthermore, S-316 (a Horiba Instruments Inc. high molecular weight, non-ODS chlorofluorocarbon) was found to be an adequate replacement for Freon-113 as a solvent to reconstitute non-volatile residue removed from a Cold Trap during oxygen testing for subsequent HC (hydrocarbon) analysis via FTIR (Fourier Transform Infrared Spectroscopy)

Agronomic characteristics and nutritive value of elephant grass clones managed under rotational stocking during the dry period.

This study aimed to evaluate the agronomic characteristics and nutritional value of two clones of elephant grass (CNPGL 00-1-3 and BRS Kurumi) operating under rotational stocking in the dry season. A completely randomized design with repeated measures (grazing cycles) and three replicates (paddocks) was used. Clones were managed under rotational stocking with a defoliation interval of 24 days and four days of occupation of paddocks, using Holstein x Gyr heifers with mean body weight of 150 kg. The evaluations were conducted in April/May, May/June, June/July and July/August 2010. Green forage mass was influenced by clone and grazing cycle, with higher mean value observed for CNPGL 03-01-00, which was 17% higher than the value observed for BRS Kurumi, and there was decreased of dry mass of green forage with the advance of grazing cycles. Leaf mass was influenced only by grazing cycle, with gradual reduction from the first to the third cycle. However, in fourth cycle was increase in biomass of leaves, which did not differ from that observed in the second cycle. There was interaction for dry matter production of stem, being observed differences in the first and third cycles for the clones. There was no effect of the factors studied for the production of senescent material. The leaf:stem ratio was influenced by grazing cycles, with interaction of the factors studied. The clone BRS Kurumi kept the leaf:stem ratio stable over the cycles, while clone CNPGL 1-3-00 presented a decrease in leaf:stem ratio from first until to third cycle. The content of crude protein (PB) was not influenced by the factors studied, with average values of 15.3% and 15.8% PB for the CNPGL 00-1-3 and BRS Kurumi clones. Neutral detergent fiber (NDF) and the in vitro dry matter digestibility (IVDMD) were affected only by grazing cycles. The highest values of NDF were observed in the three first grazing cycles, with values of 55.5%, 56.0% and 55.7% from the first to the third grazing cycle, respectively, while in the fourth cycle was obtained the value of 50.5%. There was a decrease in the IVDMD until the third cycle. In the fourth cycle the IVDMD values were similar to the first cycle. The clones did not differ in relation to biomass production, morphological composition and nutritional value, during the dry season