2,977 research outputs found

    Flows and Non-thermal Velocities in Solar Active Regions Observed with the Extreme-ultraviolet Imaging Spectrometer on Hinode: A Tracer of Active Region Sources of Heliospheric Magnetic Fields?

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    From Doppler velocity maps of active regions constructed from spectra obtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft we observe large areas of outflow (20-50 km/s) that can persist for at least a day. These outflows occur in areas of active regions that are faint in coronal spectral lines formed at typical quiet Sun and active region temperatures. The outflows are positively correlated with non-thermal velocities in coronal plasmas. The bulk mass motions and non-thermal velocities are derived from spectral line centroids and line widths, mostly from a strong line of Fe XII at 195.12 Angstroms. The electron temperature of the outflow regions estimated from an Fe XIII to Fe XII line intensity ratio is about 1.2-1.4 MK. The electron density of the outflow regions derived from a density sensitive intensity ratio of Fe XII lines is rather low for an active region. Most regions average around 7E10+8 cm(-3), but there are variations on pixel spatial scales of about a factor of 4. We discuss results in detail for two active regions observed by EIS. Images of active regions in line intensity, line width, and line centroid are obtained by rastering the regions. We also discuss data from the active regions obtained from other orbiting spacecraft that support the conclusions obtained from analysis of the EIS spectra. The locations of the flows in the active regions with respect to the longitudinal photospheric magnetic fields suggest that these regions might be tracers of long loops and/or open magnetic fields that extend into the heliosphere, and thus the flows could possibly contribute significantly to the solar wind.Comment: one tex file, 11 postscript figure file

    Grazing Behaviour of Beef Steers Grazing Kentucky 31 Endophyte Infected Tall Fescue, Q4508-AR542 Novel Endophyte Tall Fescue, and Lakota Prairie Grass

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    Tall fescue is the most dominant grass used for pasture in the U.S. covering over 14 million ha. As a result, fescue toxicosis is a major concern among producers, especially during the summer months when the symptoms, such as reduced weight gains, are most pronounced. Producers need alternative forages for grazing cattle that do not have the negative effects associated with endophyte infected tall fescue. The objective of this experiment was to determine the grazing behaviour of cattle on Kentucky 31 endophyte infected (E+) tall fescue (Festuca arundinacea Schreb.), Q4508-AR542 (Q) novel endophyte tall fescue, and Lakota (L) prairie grass (Bromus catharticus)

    Comparison of bioactivities, binding properties and intra-follicular levels of bovine follistatins

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    Five isoforms of follistatin (FST) (Mr 31, 33, 35, 37, 41kDa) were purified from bovine follicular fluid (bFF). Comparison of their activin- and heparan sulphate proteoglycan (HSP)-binding properties and bio-potencies in neutralization of activin-A action in vitro revealed that all five isoforms bound activin-A, but with different affinities. Only the 31kDa isoform (FST-288) bound to HSP. FST-288 also showed the greatest biopotency with 35 and 41kDa isoforms being least potent. To determine whether bovine follicle development is associated with changing intrafollicular FST and activin profiles, we analyzed bFF from dominant (DF) and subordinate (SF) follicles collected at strategic times during a synchronized estrous cycle. Total FST, activin-A and activin-AB were measured by immunoassay while individual FST isoforms were quantified by immunoblotting. Follicle diameter was positively correlated with estrogen:progesterone ratio (r=0.56) in bFF but negatively correlated with activin-A (r=-0.34), activin-AB (r=-0.80) and ‘total’ FST (r=-0.70) levels. Follicle diameter was positively correlated with abundance of the 41 kDa isoform (r=0.59) but negatively correlated with abundance of 33 and 31 kDa isoforms (r=-0.56, -0.41). Both follicle status (DF vs SF) and cycle stage affected total FST, activin-A, activin-B levels while follicle status, but not cycle stage, affected abundance of 41, 37, 33 and 31kDa FST isoforms. Collectively, these findings indicate that intrafollicular FST isoforms that differ in their ability to bind and neutralise activins and associate with cell-surface proteoglycans, show divergent changes during follicle development. Enhanced FST production may have an important negative role, either directly or via inhibition of the positive effects of activins, on follicle growth and function during follicular waves

    An investigation into the factors associated with ewe colostrum production

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    peer-reviewedThe majority of lamb mortality which occurs during the first 24 h post-partum is preventable through providing the lamb with sufficient quantities of high quality colostrum during this time. Data from seven late gestation nutrition experiments carried out at this institute between 2002 and 2014 were collated into a single data set comprising of 415 twin bearing ewes. Analysis was carried out to investigate the key drivers of ewe colostrum production excluding nutrient intake, namely body reserve mobilisation, ewe breed type, ewe age, gestation length and lamb birth weight. The volume of colostrum produced at 1 and 18 h post-partum was significantly lower than the volume recorded at 10 h post-partum (P = 0.01). Multivariate regression analysis indicated that colostrum volume during the first 18 h post-partum was influenced by lamb birth weight (P = 0.01), ewe age (P = 0.01), breed type (P = 0. 01) and gestation length (P = 0.06). Live weight change (P = 0.05) also had a significant influence on the volume of colostrum produced but BCS change did not affect colostrum production (P = 0.25). Further multivariate regression analysis indicated that IgG yield was influenced ewe breed type (P = 0.01), lamb birth weight (P = 0.02), gestation length (P = 0.05) and BCS change (P = 0.04). Live weight change (P = 0.12) and ewe age (P = 0.62) did not influence the quantity of IgG produced. Leicester ewes produced less colostrum per kg lamb birth weight at 1 h post-partum compared to all other ewe breed types (P = 0.01) and less than Suffolk ewes at 10 h post-partum (P = 0.01). The result of this analysis shows the key factors excluding ewe nutrition that drive colostrum production. Ewe breed type in particular appears to play an important role in the ability of the ewe to produce sufficient quantities of adequate quality colostrum. In conclusion the result of this analysis highlights the important factors associated with ewe colostrum volume and IgG yield excluding nutrition. In particular the overall structure of the flock such as breed type and ewe age is important when considering the ability of the flock to meet colostrum demands and hence reduce lamb mortality

    Use of Alkanes to Estimate Dry Matter Intake of Beef Steers Grazing High Quality Pastures

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    Pastures remain the most important source of nutrients for ruminant livestock and nutrition is critical to optimize animal production. The daily quantity of dry matter that is consumed by an animal is a critical measurement to make nutritional inferences about feed and subsequent animal response. Researchers are facing the dilemma that, while estimates of individual animal performance are readily obtained, it is still difficult to estimate the herbage intake of individual animals. The objectives of this experiment were to estimate forage intake in beef steers grazing tall fescue (Festuca arundinacea Schreb.) and alfalfa (Medicago sativa)/tall fescue pastures and to measure the recovery rate of artificial alkanes from a controlled release device under these conditions

    A BODIPY derivative for selective fluorescent chemosensing of iron (III)

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    A BODIPY derivative functionalized with a phenyl group at the meso-position was synthesized and characterized through 1H NMR and UV–Vis absorption/emission spectroscopies. The compound showed an absorption band at 497 nm and a fluorescence band at 513 nm, with a ΦF = 0.68 in acetonitrile. The evaluation of the chemosensing ability of the BODIPY was investigated in the presence of several ions with environmental and biomedical relevance. A highly selective fluorimetric response was observed for Fe3+ through fluorescence quenching upon successive additions of this cation.The authors acknowledge Fundação para a Ciência e Tecnologia—FCT (Portugal) for funding through CQUM (UID/QUI/00686/2020) and a PhD grant to R.C.R. Gonçalves (SFRH/BD/05278/2020). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT
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