10,888 research outputs found

    Measurement of bone quality in growing male rats using dual energy x-ray absorptiometry and bone ash content : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Animal Science at Massey University, Palmerston North, New Zealand

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    Growing male rats have been considered and used as a model for bone growth and prevention of osteoporosis because of their high bone turnover and demand for calcium. Dual Energy X-ray Absorptiometry (DEXA) is a useful tool for identifying minimal changes in bone mineral density and has recently been adapted for use in small animal models. The objective of this trial was to identify the changes in Bone Mineral Density (BMD) in relation to age and to identify how BMD varies from site to site. Sixty male Sprague-Dawley rats were split into six groups to allow measurements at one, two, three, four, five and six months of age (n=10 per group). At each time point a group of rats was scanned using a QDR4000 DEXA machine from Hologic. Duplicate BMD measurements were obtained for the whole body, spine and both femurs in vivo. The rats were then euthanased and the spine and both femurs were excised for ex vivo DEXA scanning and ashed calcium analysis. BMD increased almost linearly to four months and then formed a plateau. This indicates that from weaning to four months is an especially sensitive time for manipulating bone growth in male rats. There was a significant difference in BMD between groups (P<0.001), which is to be expected in growing rats. There was also a significant difference in BMD within groups (p<0.001), believed to be due to variation at two and five months of age. There was a very strong positive correlation between weight and BMD and age and BMD at all sites, indicating that BMD is a strongly related to both weight and age. All sites were strongly correlated to each other and to the ashed calcium values. The excised femur had a lower BMD value than the in vivo femur, although the two values were strongly correlated. This is believed to be due to differences in positioning and indicates that the two methods cannot be used interchangeably. These results indicate that bone mineral density is the gold standard for following changes in bone growth over time in the growing rat. Alternatively, ashed bone calcium content can be used, but only as a once off endpoint

    Postpartum Depression Screening of Women Veterans in Alaska Quality Improvement Project

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    A Project Submitted in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE in Nursing SciencePostpartum depression screening guidelines were updated by the American College of Obstetricians and Gynecologists and the United States Preventive Services Task Force in 2015 and 2016, respectively. Universal postpartum depression screening is recommended where previously it was not. Postpartum depression screening is relevant to the rapidly growing population of women Veterans served by the Veterans Health Administration (VA) as part of their comprehensive health care benefits. Little information was available on the postpartum depression screening practices within the Alaska VA Healthcare System. Using a quality improvement methodology, the author identified postpartum depression screening as a topic of interest. Current practice was assessed through a retrospective chart audit of all maternity consults placed during the fiscal year 2014. The chart audit revealed an 81% postpartum depression screening rate. Incomplete data limited a full statistical analysis; however, all women who returned to an Alaska VA clinic, received screening and treatment. An informational brochure was developed for women and their health care providers highlighting postpartum depression screening and treatment resources.Title Page / Abstract / Table of Contents / List of Tables / List of Appendices / Introduction / Purpose / Literature Review / Implications for Nursing Practice / Methods / Results / Discussion / Conclusion / References / Appendice

    Connecting to Students: Launching Instant Messaging Reference at Binghamton University

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    Binghamton University Libraries implemented an IM reference service using the Trillian client to monitor multiple IM accounts at two distinct reference service points. This paper addresses the process and practical considerations of implementing the service including selection of the appropriate software, creation of IM accounts for each service, development of a staffing schedule, and training of reference staff. Also included is an outline of future plans for improving IM services for students and academic library users

    Solar Obliquity Induced by Planet Nine

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    The six-degree obliquity of the sun suggests that either an asymmetry was present in the solar system's formation environment, or an external torque has misaligned the angular momentum vectors of the sun and the planets. However, the exact origin of this obliquity remains an open question. Batygin & Brown (2016) have recently shown that the physical alignment of distant Kuiper Belt orbits can be explained by a 5-20 Earth-mass planet on a distant, eccentric, and inclined orbit, with an approximate perihelion distance of ~250 AU. Using an analytic model for secular interactions between Planet Nine and the remaining giant planets, here we show that a planet with similar parameters can naturally generate the observed obliquity as well as the specific pole position of the sun's spin axis, from a nearly aligned initial state. Thus, Planet Nine offers a testable explanation for the otherwise mysterious spin-orbit misalignment of the solar system.Comment: 8 pages, 4 figures, manuscript #: AAS01477, submitted on June 24, 201

    Feasibility of a resonance-based Planet Nine search

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    It has been proposed that mean motion resonances (MMRs) between Planet Nine and distant objects of the scattered disk might inform the semimajor axis and instantaneous position of Planet Nine. Within the context of this hypothesis, the specific distribution of occupied MMRs largely determines the available constraints. Here we characterize the behavior of scattered Kuiper Belt objects arising in the presence of an eccentric Planet Nine (e9∈0.1e_9 \in 0.1, 0.70.7), focusing on relative sizes of populations occupying particular commensurabilities. Highlighting the challenge of predicting the exact MMR of a given object, we find that the majority of resonant test particles have period ratios with Planet Nine other than those of the form P9/P=N/1P_9/P=N/1, N/2N/2 (N∈Z+)(N \in \mathbb{Z}^+). Taking into account the updated prior distribution of MMRs outlined in this work, we find that the close spacing of high-order resonances, as well as chaotic transport, preclude resonance-based Planet Nine constraints from current observational data.Comment: 6 pages, 7 figure
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