Novel applications for TAZ-8A

Recent needs in the non-aerospace industrial sector have revitalized interest in high performance alloys. TAZ-8A has a combination of properties that makes it unique: a high temperature strength, oxidation resistance, abrasion resistance, and exceptional thermal shock resistance. The major drawback for the utilization of this alloy is the relatively high cost compared with the more common iron base alloys. Reduced material consumption and lower costs are possible by using coatings of TAZ-8A on a low cost substrate. Coatings were applied using plasma spray techniques developed by NASA as well as modified plasma vapor deposition (PVD) techniques

The incidence of venous thromboembolism and pharmacologic thromboprophylaxis following major urologic surgery: a population-based analysis

Thesis (M.A.)--Boston UniversityINTRODUCTION: The incidence of symptomatic venous thromboembolism (VTE), which comprises deep venous thrombosis (DVT) and pulmonary embolism (PE) at a population-based level remains unknown in patients undergoing major urologic surgery. Our aim was to determine the incidence of VTE in major urologic surgery, identify patients who are at high risk for developing these events, and to examine whether the use of pharmacologic thromboprophylaxis is associated with a reduction in the incidence of VTE in major urologic surgery. METHODS: We captured all adult patients who underwent major urologic surgery between January 2005 and December 2010 based on 1CD-9-CM codes from the Perspective Database (Premier, Inc, Charlotte, NC), a nationally representative dataset capturing 25% of US hospital discharges. Major urologic surgery was defined as a radical prostatectomy, radical cystectomy, radical nephrectomy or partial nephrectomy. We used ICD-9-CM codes to identify VTE and major bleeding after major urologic surgery within 90 days after the procedure and hospital billing descriptions to identify if patients had received pharmacologic thromboprophylaxis beginning the day of surgery. Univariate and multivariate analyses were performed using STATA 12 (StataCorp LP, CollegeStation, Texas) after adjusting for sample weights. [TRUNCATED

The relationship between teachers' understanding of the nature of science and their science practice : four case studies from an urban primary school.

This is a digitised version of a thesis that was deposited in the University Library. If you are the author and you have a query about this item please contact PEARL Admin ([email protected])Merged with duplicate record (10026.1/432) on 03.01.2017 by CS (TIS)This thesis explores the relationship between a teacher's understanding of the nature of science and her practice. The idea that teachers' understanding of the nature of science is a powerful determinant of their actions in the classroom has a strong intuitive appeal. Research over the last forty years has provided inconclusive results; however, there is a clear implication within recent central policy on teacher education that such knowledge should translated directly into practice. This has led to the identification within teacher training, materials of specific expectations regarding understanding of the nature of science (DfEE 1998a). This thesis presents four case studies of the science teaching of primary teachers. The studies derive from data collected over the course of a year and analyse evidence of the teachers' ideas, both tacit and espoused, about the nature of science against their practice in the classroom. The research employed a methodology unlike other studies in the field. Primary teachers frequently lack experience of reflection on the philosophy of science, and their actions may convey tacit ideas different from those they espouse. In order to ensure that, a mechanism existed to facilitate elicitation of the teachers' philosophical understanding, to render possible the identification of any tacit ideas and to enable the inherent dialectical nature of theory and action within practice to be accommodated, the participating teachers were encouraged to engage in action research on their own practice. Data generated by this personal inquiry then served as evidence for the main research questions. This methodology yields results which are closely derived from the everyday reality of teachers' practice. The findings indicate that teachers' understanding of the nature of science does not translate directly into predictable approaches to science teaching. Teachers' understanding of the nature of science is seen to be mediated strongly by their pedagogical beliefs and aims and it is these beliefs that assume overriding importance in the derivation of science practice. These findings extend previous research results. They suggest that the development of science practice will need to have regard for factors other than mere extension of knowledge, raising implications for both preservice and inservice teacher education.Rolle School of Education Researc

Luminosity Function of Faint Globular Clusters in M87

We present the luminosity function to very faint magnitudes for the globular clusters in M87, based on a 30 orbit \textit{Hubble Space Telescope (HST)} WFPC2 imaging program. The very deep images and corresponding improved false source rejection allow us to probe the mass function further beyond the turnover than has been done before. We compare our luminosity function to those that have been observed in the past, and confirm the similarity of the turnover luminosity between M87 and the Milky Way. We also find with high statistical significance that the M87 luminosity function is broader than that of the Milky Way. We discuss how determining the mass function of the cluster system to low masses can constrain theoretical models of the dynamical evolution of globular cluster systems. Our mass function is consistent with the dependence of mass loss on the initial cluster mass given by classical evaporation, and somewhat inconsistent with newer proposals that have a shallower mass dependence. In addition, the rate of mass loss is consistent with standard evaporation models, and not with the much higher rates proposed by some recent studies of very young cluster systems. We also find that the mass-size relation has very little slope, indicating that there is almost no increase in the size of a cluster with increasing mass.Comment: 22 pages, 5 figures, Accepted for publication in Ap

Effect of supplementation with different fat sources on the mechanisms involved in reproductive performance in lactating dairy cattle

peer reviewedSupplementary fat positively influences reproductive performance in dairy cattle, although the mechanisms involved are not clearly defined. Our objective was to determine the effects of four different fat supplements on follicle development, plasma steroid hormone concentrations and prostaglandin (PG) synthesis in lactating dairy cattle. Forty-eight early lactation Holstein-Friesian cows (21 primiparous, 27 multiparous) were used in a completely randomized block design. Cows were fed the same basal TMR diet and received one of four fat supplements: (i) palmitic acid (18:0 fatty acid; Control), (ii) flaxseed (rich in 18:3 n-3 fatty acid; Flax), (iii) conjugated linoleic acid (a mixture of cis-9, trans-11 and trans-10, cis-12 isomers; CLA), and (iv) fish oil (rich in 20:5 and 22:6 n-3 fatty acids; FO). All lipid supplements were formulated to be isolipidic; palmitic acid was added as necessary to provide a total lipid supplement intake of 500 g/day. Cows were synchronized to be in estrus on Day 15 of dietary treatment. All antral follicles were counted, and dominant follicles, subordinate follicles and corpora lutea were measured daily via transrectal ovarian ultrasonography for one complete estrous cycle. Blood samples were collected daily, and selected samples were analyzed for progesterone, estradiol, insulin-like growth factor-1, insulin, cholesterol and non-esterified fatty acids. Estrus was synchronized a second time, and liver and endometrial biopsies were collected on Day 7 of the estrous cycle. Gene expression was evaluated for a number of genes involved in prostaglandin synthesis (endometrium) and fatty acid uptake and utilization (liver). Fat supplementation had little effect on follicle development. Cows receiving supplementary n-3 fatty acids had lesser plasma progesterone (P4) and smaller corpora lutea than cows receiving the CLA or Control supplements. Effects of fat supplementation on the endometrial expression of genes involved in PG synthesis were minor. Hepatic expression of SREBF1, ASCL1 and FABP1 was reduced by FO supplementation. Reduced plasma P4 in n-3 supplemented cows may lead to a suboptimal uterine environment for embryo development and hence reduced fertility compared to cows receiving the control or CLA supplements

Stokes flows in a 2D bifurcation

The flow network model is an established approach to approximate pressure-flow relationships in a network, which has been widely used in many contexts. However, little is known about the impact of bifurcation geometry on such approximations, so the existing models mostly rely on unidirectional flow assumption and Poiseuille's law, and thus neglect the flow details at each bifurcation. In this work, we address these limitations by computing Stokes flows in a 2D bifurcation using LARS (Lightning-AAA Rational Stokes), a novel mesh-free algorithm for solving 2D Stokes flow problems utilising an applied complex analysis approach based on rational approximation of the Goursat functions. Using our 2D bifurcation model, we show that the fluxes in two child branches depend on not only pressures and widths of inlet and outlet branches, as most previous studies have assumed, but also detailed bifurcation geometries (e.g. bifurcation angle), which were not considered in previous studies. The 2D Stokes flow simulations allow us to represent the relationship between pressures and fluxes of a bifurcation using an updated flow network, which considers the bifurcation geometry and can be easily incorporated into previous flow network approaches. The errors in the flow conductance of a channel in a bifurcation approximated using Poiseuille's law can be greater than 16%, when the centreline length is twice the inlet channel width and the bifurcation geometry is highly asymmetric. In addition, we present details of 2D Stokes flow features, such as flow separation in a bifurcation and flows around fixed objects at different locations, which previous flow network models cannot capture. These findings suggest the importance of incorporating detailed flow modelling techniques alongside existing flow network approaches when solving complex flow problems

Ultraviolet HST Observations of the Jet in M87

We present new ultraviolet photometry of the jet in M87 obtained from HST WFPC2 imaging. We combine these ultraviolet data with previously published photometry for the knots of the jet in radio, optical, and X-ray, and fit three theoretical synchrotron models to the full data set. The synchrotron models consistently overpredict the flux in the ultraviolet when fit over the entire dataset. We show that if the fit is restricted to the radio through ultraviolet data, the synchrotron models can provide a good match to the data. The break frequencies of these fits are much lower than previous estimates. The implied synchrotron lifetimes for the bulk of the emitting population are longer than earlier work, but still much shorter than the estimated kinematic lifetimes of the knots. The observed X-ray flux cannot be successfully explained by the simple synchrotron models that fit the ultraviolet and optical fluxes. We discuss the possible implications of these results for the physical properties of the M87 jet. We also observe increased flux for the HST-1 knot that is consistent with previous results for flaring. This observation fills in a significant gap in the time coverage early in the history of the flare, and therefore sets constraints on the initial brightening of the flare.Comment: 14 pages, 2 figures, Accepted for publication in ApJ, changed lightcurve and caption in Figure

Forecasts for the WFIRST High Latitude Survey using the BlueTides Simulation

We use the BlueTides simulation to predict the properties of the high-z galaxy and active galactic nucleus (AGN) populations for the planned 2200 deg2 Wide-Field Infrared Survey Telescope's (WFIRST) High Latitude Survey (HLS). BlueTides is a cosmological hydrodynamic simulation, which incorporates a variety of baryon physics in a (400 h−1 Mpc)3 volume evolved to z = 8 with 0.7 trillion particles. The galaxy luminosity functions in the simulation show good agreement with all the current observational constraints (up to z = 11) and predict an enhanced number of UV bright galaxies. At the proposed depth of the HLS (mUV < 26.75), BlueTides predicts 106 galaxies at z = 8 with a few up to z ∼ 15 due to the enhanced bright end of the galaxy luminosity function. At z = 8, galaxies in the mock HLS have specific star formation rates of ∼10 Gyr−1 and ages of ∼80 Myr (both evolving linearly with redshift) and a non-evolving mass–metallicity relation. BlueTides also predicts ∼104 AGN in WFIRST HLS from z = 8 out to z ∼ 14. These AGN host black holes of M ∼ 106–108 M⊙ accreting close to their Eddington luminosity. Galaxies and AGN have host halo masses of Mhalo ∼ 1011–12 M⊙ and a linear bias b ≈ 13–20. Given the expected galaxy space densities, their high bias and large volume probed, we speculate that it may be feasible for WFIRST HLS to detect the baryon acoustic oscillation peak in the galaxy power spectrum out to z = 8–9

Translocation and Recovery Efforts for the Telkwa Caribou, Rangifer tarandus caribou, Herd in Westcentral British Columbia, 1997-2005

During 1997–1999, 32 Woodland Caribou (Rangifer tarandus caribou) were translocated from the Sustut Herd to the Telkwa Mountains in westcentral British Columbia to augment recovery of the Telkwa Caribou Herd. The animals were fitted with radiocollars and located during 1997–2000 to determine selection of habitat features and terrain variables. Six Caribou calves were also collared to determine causes and timing of calf mortality during summer 1999. Defining available habitat for newly translocated animals is often arbitrary and subjective, and we based the analyses on ranks for habitat use and availability as this is less sensitive to the inclusion or exclusion of a questionable resource. This method represents some loss of information but provides indications of the relative importance of various habitat types without classifying any as avoided. High elevation habitat (&gt; 1700 masl) on moderate slopes (16 – 45°) received the highest ranks, as did “warm” (136 – 315°) aspects and forests &gt; 250 years old. Three calves died shortly after birth. One calf appeared to have been killed by predation, likely by a Golden Eagle (Aquila chrysaetos), and one calf was abandoned by the cow. Cause of death for the third calf is unknown. To assess habitat use associated with calving we compared summer locations with data obtained throughout the rest of 1999 for eight cows with calves and eight without calves. We found significant difference in use of elevation during calving time, when cows with calves remained at high elevations and barren cows generally descended to lower elevation habitat. Surveys conducted in 2005, five years after the completion of the initial study, produced a count of approximately 90 Caribou. This suggests that in the short term, the translocation was successful in re-establishing a self-sustaining Caribou population in the Telkwa Mountains