3,661 research outputs found
A multi-wavelength, Hubble space telescope study of two globular clusters
No full textGlobular clusters (GCs) are among the densest and oldest stellar aggregates in the Galaxy, and are thought to date from around the time that the Galaxy first formed. The high central densities that characterise GCs lead to frequent stellar interactions and the formation of exotic stellar populations, making GCs excellent laboratories for studying the stellar dynamics of dense environments. The ability to observe many stars which are equidistant and (approximately) the same age makes GCs invaluable in understanding stellar structure and evolution.This thesis describes surveys of two Galactic GCs: far- and near-ultraviolet data from the Advanced Camera for Surveys (ACS) on-board the Hubble Space Telescope (HST) were used to study the core region of M80, and far-ultraviolet to Iband data from the Space Telescope Imaging Spectrograph (STIS), ACS and the Wide Field Camera 3 (WFC3) on-board HST were used to carry out an in-depth, multi-wavelength survey of NGC6752. In both studies, the properties of key stellar populations resident in globular clusters are investigated.In M80, it was discovered that the fainter (redder) blue straggler stars are more centrally concentrated than the brighter (bluer) ones. This is contrary to expectations, and suggests that blue stragglers might get a ‘kick’ at formation, before settling back towards the core. In a search for counterparts to known X-ray sources in M80, one X-ray source was shown to be the remnant of the classical nova T Scorpii. This source was undergoing a dwarf nova outburst during the observations. A variability study of the GC also revealed three variable sources, including an RR Lyrae that was observed around maximum brightness, an SXPhoenicis star with a ? 55minute period, and a longer period variable which might be another RR Lyrae or a Cepheid variable.In NGC6752, two known cataclysmic variables were revealed to be dwarf novae (DNe), which underwent outbursts during the observations. This takes the number of known DNe in NGC6752 to three, more than any other cluster. Some of the global parameters describing NGC6752 were also investigated. A new estimate of the cluster’s centre position was determined and used to show that the stellar density profile cannot be fit using a single ‘King’ profile, indicating that the cluster is in a core-collapsed state. Finally, a search for broadening in the main-sequence of the colour-magnitude diagram found evidence of small-scale broadening, suggesting the presence of multiple populations. A radial trend in the level of observed broadening was also suggested, with more broadening found in the core than the outer parts of the cluster
Author Co-Citation Analysis (ACA): a powerful tool for representing implicit knowledge of scholar knowledge workers
No full textIn the last decade, knowledge has emerged as one of the most important and valuable organizational assets. Gradually this importance caused to emergence of new discipline entitled ―knowledge management‖. However one of the major challenges of knowledge management is conversion implicit or tacit knowledge to explicit knowledge. Thus Making knowledge visible so that it can be better accessed, discussed, valued or generally managed is a long-standing objective in knowledge management. Accordingly in this paper author co- citation analysis (ACA) will be proposed as an efficient technique of knowledge visualization in academia (Scholar knowledge workers)
Multiple rare earth emissions in a multicore tellurite ber with a single pump wavelength
No full textCattle handling technique can induce fatigued cattle syndrome in cattle not fed a beta adrenergic agonist
No full textCitation: Frese, D. A., Reinhardt, C. D., Bartle, S. J., Rethorst, D. N., Hutcheson, J. P., Nichols, W. T., . . . Thomson, D. U. (2016). Cattle handling technique can induce fatigued cattle syndrome in cattle not fed a beta adrenergic agonist. Journal of Animal Science, 94(2), 581-591. doi:10.2527/jas2015-9824Angus crossbred steers (n = 40; 563 +/- 44 kg) were used to examine the effects of handling method and fat thickness on the blood chemistry and physiology of market steers. Steers were blocked by backfat (BF) thickness and were randomly assigned to treatment groups: low-stress handling (LSH) and aggressive handling (AH). Cattle were then ran-domly assigned to one of 5 blocks containing 4 steers from the LSH and AH treatments. Steers in the LSH treatment were walked and AH cattle were run through a course of 1,540 m. Blood samples were obtained via jugular venipuncture before handling (BASE), at 770 m (LAP1), at 1,540 m (LAP2), and at1 h (1H) and 2 h (2H) after finishing the course. Blood samples were analyzed for plasma lactate (LAC), creatinine kinase (CK), base excess (BE), blood pH (pH), serum cortisol (CORT) concentrations, and venous carbon dioxide (PvCO2) and oxygen (PvO2) pressures. Heart rate (HR), respiratory rate (RR), and rectal temperature (TEMP) were measured at the same intervals. Cattle in the AH treatment had greater (P 0.14). Blood pH in AH cattle was decreased compared with that in LSH cattle (P 0.13) at BASE, 1H, or 2H. Heart rate and TEMP were increased in AH cattle compared to LSH (P > 0.01). Serum cortisol was increased (P < 0.05) in AH compared to that in LSH cattle at LAP1 (87.5 vs. 58.9 nmol/ L), LAP2 (144.4 vs. 93.1 nmol/ L), and 1H (113.5 vs. 53.1 nmol/ L). Although RR was not differ-ent between LSH and AH, PvCO2 was decreased in AH compared to that in LSH (P < 0.05) at LAP2 (30.6 vs. 39.3 mmHg) and PvO2 was increased at LAP1 (42.7 vs. 33.5 mmHg) and at LAP2 (51.5 vs. 36.6 mmHg). Lactate was increased in AH cattle in the thicker BF group at 1H (P < 0.05), and blood pH was decreased at LAP1, LAP2, and 1H (P < 0.05) compared to the thinner BF cohorts. Four AH steers became exhausted (EXH) and did not complete the course. Increased CK, decreased PvCO2, and muscle tremors occurred in EXH steers compared to non-exhausted AH cohorts. Results of this study show that AH causes physiologic and blood chemistry changes in steers, which can be potentially detrimental to cattle, emphasizing the need for lowstress handling practices
Analysis of MicroRNA Expression in Embryonic Developmental Toxicity Induced by MC-RR
No full textAs cynobacterial blooms frequently occur in fresh waters throughout the world, microcystins (MCs) have caused serious damage to both wildlife and human health. MCs are known to have developmental toxicity, however, the possible molecular mechanism is largely unknown. This is the first toxicological study to integrate post-transcriptomic, proteomic and bioinformatics analysis to explore molecular mechanisms for developmental toxicity of MCs in zebrafish. After being microinjected directly into embryos, MC-RR dose-dependently decreased survival rates and increased malformation rates of embryos, causing various embryo abnormalities including loss of vascular integrity and hemorrhage. Expressions of 31 microRNAs (miRNAs) and 78 proteins were significantly affected at 72 hours post-fertilisation (hpf). Expressions of miR-430 and miR-125 families were also significantly changed. The altered expressions of miR-31 and miR-126 were likely responsible for the loss of vascular integrity. MC-RR significantly reduced the expressions of a number of proteins involved in energy metabolism, cell division, protein synthesis, cytoskeleton maintenance, response to stress and DNA replication. Bioinformatics analysis shows that several aberrantly expressed miRNAs and proteins (involved in various molecular pathways) were predicted to be potential MC-responsive miRNA-target pairs, and that their aberrant expressions should be the possible molecular mechanisms for the various developmental defects caused by MC-RR
The proteomic study on cellular responses of the testes of zebrafish (Danio rerio) exposed to microcystin-RR
No full textMicrocystin-RR (MC-RR) is a commonly encountered cyanotoxin and receives increasing attention due to the risk of its bioaccumulation in aquatic animals like fish. This study investigated the protein profiles of zebrafish (Danio rerio) testes after intraperitoneal injection (i.p.) with 0.5 LD50 (2000 mu g/kg). MC-RR caused a noticeable damage to testicular ultrastructure, showing widened intercellular junction, distention of mitochondria. The testes showed a rapid response of its defense systems to the oxidative stress caused by MC-RR. This is the first to use a proteomic approach to obtain an overview of the effects of MC-RR on the testes of zebrafish. The proteomic results revealed that toxin exposure remarkably altered the abundance of 24 proteins that were involved in cytoskeleton assembly, oxidative stress, glycolysis metabolism, calcium ion binding and other biological functions. In conclusion, MC-RR damaged the testes and was toxic to the reproductive system of male zebrafish mainly through causing oxidative stress.Microcystin-RR (MC-RR) is a commonly encountered cyanotoxin and receives increasing attention due to the risk of its bioaccumulation in aquatic animals like fish. This study investigated the protein profiles of zebrafish (Danio rerio) testes after intraperitoneal injection (i.p.) with 0.5 LD50 (2000 mu g/kg). MC-RR caused a noticeable damage to testicular ultrastructure, showing widened intercellular junction, distention of mitochondria. The testes showed a rapid response of its defense systems to the oxidative stress caused by MC-RR. This is the first to use a proteomic approach to obtain an overview of the effects of MC-RR on the testes of zebrafish. The proteomic results revealed that toxin exposure remarkably altered the abundance of 24 proteins that were involved in cytoskeleton assembly, oxidative stress, glycolysis metabolism, calcium ion binding and other biological functions. In conclusion, MC-RR damaged the testes and was toxic to the reproductive system of male zebrafish mainly through causing oxidative stress
So Tom has turned a poet, what a dear [first line]
No full textstrophicnasame as Box 192 Item 50Cover is duplicated in 192.050.
Music is duplicated in 192.050.Johns Hopkins University, Levy Sheet Music Collection, Box
192, Item 051Thomas M-rr-s, Author of "How They Act in Baltimore." "Mephistophiles K.G.S.
So Tom has turned a poet, what a dear [first line]
No full textstrophicnasame as Box 192 Item 50Cover is duplicated in 192.050.
Music is duplicated in 192.050.Johns Hopkins University, Levy Sheet Music Collection, Box
192, Item 051Thomas M-rr-s, Author of "How They Act in Baltimore." "Mephistophiles K.G.S.
So Tom has turned a poet, what a dear [first line]
No full textstrophicnaCover is duplicated in 192.051.
Music is duplicated in 192.051.Johns Hopkins University, Levy Sheet Music Collection, Box
192, Item 050Thomas M-rr-s, Author of "How They Act in Baltimore." "Mephistophiles K.G.S.
So Tom has turned a poet, what a dear [first line]
No full textstrophicnaCover is duplicated in 192.051.
Music is duplicated in 192.051.Johns Hopkins University, Levy Sheet Music Collection, Box
192, Item 050Thomas M-rr-s, Author of "How They Act in Baltimore." "Mephistophiles K.G.S.
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