2,318 results on '"Waite I"'
Search Results
2. Planets around young active Solar-type stars: Assessing detection capabilities from a non stabilised spectrograph
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Heitzmann, A., Marsden, S. C., Petit, P., Mengel, M. W., Wright, D., Clerte, M., Millburn, I., Folsom, C. P., Addison, B. C., Wittenmyer, R. A., and Waite, I. A.
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Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Short-orbit gas giant planet formation/evolution mechanisms are still not well understood. One promising pathway to discriminate between mechanisms is to constrain the occurrence rate of these peculiar exoplanets at the earliest stage of the system's life. However, a major limitation when studying newly born stars is stellar activity. This cocktail of phenomena triggered by fast rotation, strong magnetic fields and complex internal dynamics, especially present in very young stars, compromises our ability to detect exoplanets. In this paper, we investigated the limitations of such detections in the context of already acquired data solely using radial velocity data acquired with a non-stabilised spectrograph. We employed two strategies: Doppler Imaging and Gaussian Processes and could confidently detect Hot Jupiters with semi-amplitude of 100 $m.s^{-1}$ buried in the stellar activity. We also showed the advantages of the Gaussian Process approach in this case. This study serves as a proof of concept to identify potential candidates for follow-up observations or even discover such planets in legacy datasets available to the community., Comment: 16 pages, 13 figures, 11 pages appendix, accepted for publication in MNRAS
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- 2021
3. United States Tax court's order in the case of JONATHAN A. WAITE & I. BURGOS DE ) WAITE ROSA, ) ) Petitioners, v. COMMISSIONER OF INTERNAL REVENUE,Respondent (Docket No. 13794-19S. )
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United States. Tax Court -- Cases ,Company legal issue ,News, opinion and commentary - Abstract
Washington: United States Tax Court has issued the following order: SD UNITED STATES TAX COURT WASHINGTON, DC 20217 JONATHAN A. WAITE & I. BURGOS DE ) WAITE ROSA, ) ) [...]
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- 2020
4. Studying stellar spin-down with Zeeman-Doppler magnetograms
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See, V., Jardine, M., Vidotto, A. A., Donati, J. -F., Saikia, S. Boro, Fares, R., Folsom, C. P., Hebrard, E. M., Jeffers, S. V., Marsden, S. C., Morin, J., Petit, P., Waite, I. A., and Collaboration, BCool
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Astrophysics - Solar and Stellar Astrophysics - Abstract
Magnetic activity and rotation are known to be intimately linked for low-mass stars. Understanding rotation evolution over the stellar lifetime is therefore an important goal within stellar astrophysics. In recent years, there has been increased focus on how the complexity of the stellar magnetic field affects the rate of angular momentum-loss from a star. This is a topic that Zeeman-Doppler imaging (ZDI), a technique that is capable of reconstructing the large-scale magnetic field topology of a star, can uniquely address. Using a potential field source surface model, we estimate the open flux, mass loss-rate and angular momentum-loss rates for a sample of 66 stars that have been mapped with ZDI. We show that the open flux of a star is predominantly determined by the dipolar component of its magnetic field for our choice of source surface radius. We also show that, on the main sequence, the open flux, mass- and angular momentum-loss rates increase with decreasing Rossby number. The exception to this rule is stars less massive than $0.3M_{\odot}$. Previous work suggests that low mass M dwarfs may possess either strong, ordered and dipolar fields or weak and complex fields. This range of field strengths results in a large spread of angular momentum-loss rates for these stars and has important consequences for their spin down behaviour. Additionally, our models do not predict a transition in the mass-loss rates at the so called wind dividing line noted from Ly$\alpha$ studies., Comment: 14 pages, 8 figures, 2 tables, accepted to MNRAS
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- 2017
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5. The connection between stellar activity cycles and magnetic field topology
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See, V., Jardine, M., Vidotto, A. A., Donati, J. -F., Saikia, S. Boro, Bouvier, J., Fares, R., Folsom, C. P., Gregory, S. G., Hussain, G., Jeffers, S. V., Marsden, S. C., Morin, J., Moutou, C., Nascimento Jr, J. D. do, Petit, P., and Waite, I. A.
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Astrophysics - Solar and Stellar Astrophysics - Abstract
Zeeman Doppler imaging has successfully mapped the large-scale magnetic fields of stars over a large range of spectral types, rotation periods and ages. When observed over multiple epochs, some stars show polarity reversals in their global magnetic fields. On the Sun, polarity reversals are a feature of its activity cycle. In this paper, we examine the magnetic properties of stars with existing chromospherically determined cycle periods. Previous authors have suggested that cycle periods lie on multiple branches, either in the cycle period-Rossby number plane or the cycle period-rotation period plane. We find some evidence that stars along the active branch show significant average toroidal fields that exhibit large temporal variations while stars exclusively on the inactive branch remain dominantly poloidal throughout their entire cycle. This lends credence to the idea that different shear layers are in operation along each branch. There is also evidence that the short magnetic polarity switches observed on some stars are characteristic of the inactive branch while the longer chromospherically determined periods are characteristic of the active branch. This may explain the discrepancy between the magnetic and chromospheric cycle periods found on some stars. These results represent a first attempt at linking global magnetic field properties obtained form ZDI and activity cycles., Comment: 9 pages, 2 figures, 2 tables, accepted to MNRAS
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- 2016
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6. Terry Waite: 'I spent five years as a hostage in Beirut - but I never cried'
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Hostages ,General interest ,News, opinion and commentary ,Hezbollah - Abstract
Byline: Peter Stanford Terry Waite, a former envoy to the Archishop of Canterbury, was captured by Hezbollah in 1987 and imprisoned for five years. He is now a writer and [...]
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- 2016
7. The energy budget of stellar magnetic fields
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See, V., Jardine, M., Vidotto, A. A., Donati, J. -F., Folsom, C. P., Saikia, S. Boro, Bouvier, J., Fares, R., Gregory, S. G., Hussain, G., Jeffers, S. V., Marsden, S. C., Morin, J., Moutou, C., Nascimento Jr, J. D. do, Petit, P., Rosen, L., and Waite, I. A.
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Astrophysics - Solar and Stellar Astrophysics - Abstract
Spectropolarimetric observations have been used to map stellar magnetic fields, many of which display strong bands of azimuthal fields that are toroidal. A number of explanations have been proposed to explain how such fields might be generated though none are definitive. In this paper, we examine the toroidal fields of a sample of 55 stars with magnetic maps, with masses in the range 0.1-1.5$\,{\rm M}_\odot$. We find that the energy contained in toroidal fields has a power law dependence on the energy contained in poloidal fields. However the power index is not constant across our sample, with stars less and more massive than 0.5$\,{\rm M}_\odot$ having power indices of 0.72$\pm$0.08 and 1.25$\pm$0.06 respectively. There is some evidence that these two power laws correspond to stars in the saturated and unsaturated regimes of the rotation-activity relation. Additionally, our sample shows that strong toroidal fields must be generated axisymmetrically. The latitudes at which these bands appear depend on the stellar rotation period with fast rotators displaying higher latitude bands than slow rotators. The results in this paper present new constraints for future dynamo studies., Comment: 10 pages, 7 figures, 2 tables, submitted to MNRAS (referee's report indicated minor revisions only)
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- 2015
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8. Winds of Planet Hosting Stars
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Nicholson, B. A., Mengel, M. W., Brookshaw, L., Vidotto, A. A., Carter, B. D., Marsden, S. C., Soutter, J., Waite, I. A., and Horner, J.
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
The field of exoplanetary science is one of the most rapidly growing areas of astrophysical research. As more planets are discovered around other stars, new techniques have been developed that have allowed astronomers to begin to characterise them. Two of the most important factors in understanding the evolution of these planets, and potentially determining whether they are habitable, are the behaviour of the winds of the host star and the way in which they interact with the planet. The purpose of this project is to reconstruct the magnetic fields of planet hosting stars from spectropolarimetric observations, and to use these magnetic field maps to inform simulations of the stellar winds in those systems using the Block Adaptive Tree Solar-wind Roe Upwind Scheme (BATS-R-US) code. The BATS-R-US code was originally written to investigate the behaviour of the Solar wind, and so has been altered to be used in the context of other stellar systems. These simulations will give information about the velocity, pressure and density of the wind outward from the host star. They will also allow us to determine what influence the winds will have on the space weather environment of the planet. This paper presents the preliminary results of these simulations for the star $\tau$ Bo\"otis, using a newly reconstructed magnetic field map based on previously published observations. These simulations show interesting structures in the wind velocity around the star, consistent with the complex topology of its magnetic field., Comment: 8 pages, 2 figures, accepted for publication in the peer-reviewed proceedings of the 14th Australian Space Research Conference, held at the University of South Australia, 29th September - 1st October 2014
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- 2015
9. Doppler images and the underlying dynamo. The case of AF Leporis
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Järvinen, S. P., Arlt, R., Hackman, T., Marsden, S. C., Küker, M., Ilyin, I. V., Berdyugina, S. V., Strassmeier, K. G., and Waite, I. A.
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Astrophysics - Solar and Stellar Astrophysics - Abstract
The (Zeeman-)Doppler imaging studies of solar-type stars very often reveal large high-latitude spots. This also includes F stars that possess relatively shallow convection zones, indicating that the dynamo operating in these stars differs from the solar dynamo. We aim to determine whether mean-field dynamo models of late-F type dwarf stars can reproduce the surface features recovered in Doppler maps. In particular, we wish to test whether the models can reproduce the high-latitude spots observed on some F dwarfs. The photometric inversions and the surface temperature maps of AF Lep were obtained using the Occamian-approach inversion technique. Low signal-to-noise spectroscopic data were improved by applying the least-squares deconvolution method. The locations of strong magnetic flux in the stellar tachocline as well as the surface fields obtained from mean-field dynamo solutions were compared with the observed surface temperature maps. The photometric record of AF Lep reveals both long- and short-term variability. However, the current data set is too short for cycle-length estimates. From the photometry, we have determined the rotation period of the star to be 0.9660+-0.0023 days. The surface temperature maps show a dominant, but evolving, high-latitude (around +65 degrees) spot. Detailed study of the photometry reveals that sometimes the spot coverage varies only marginally over a long time, and at other times it varies rapidly. Of a suite of dynamo models, the model with a radiative interior rotating as fast as the convection zone at the equator delivered the highest compatibility with the obtained Doppler images., Comment: accepted for publication in Astronomy & Astrophysics
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- 2014
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10. Can a brief behavioural change intervention encourage hospital patients with low physical activity levels to engage and initiate a change in physical activity behaviour?
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Waite, I., Grant, D., Mayes, J., and Greenwood, S.
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- 2020
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11. Stellar magnetism: empirical trends with age and rotation
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Vidotto, A. A., Gregory, S. G., Jardine, M., Donati, J. -F., Petit, P., Morin, J., Folsom, C. P., Bouvier, J., Cameron, A. C., Hussain, G., Marsden, S., Waite, I. A., Fares, R., Jeffers, S., and Nascimento Jr, J. D. do
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We investigate how the observed large-scale surface magnetic fields of low-mass stars (~0.1 -- 2 Msun), reconstructed through Zeeman-Doppler imaging (ZDI), vary with age t, rotation and X-ray emission. Our sample consists of 104 magnetic maps of 73 stars, from accreting pre-main sequence to main-sequence objects (1 Myr < t < 10 Gyr). For non-accreting dwarfs we empirically find that the unsigned average large-scale surface field <|Bv|> is related to age as $t^{-0.655 \pm 0.045}$. This relation has a similar dependence to that identified by Skumanich (1972), used as the basis for gyrochronology. Likewise, our relation could be used as an age-dating method ("magnetochronology"). The trends with rotation we find for the large-scale stellar magnetism are consistent with the trends found from Zeeman broadening measurements (sensitive to large- and small-scale fields). These similarities indicate that the fields recovered from both techniques are coupled to each other, suggesting that small- and large-scale fields could share the same dynamo field generation processes. For the accreting objects, fewer statistically significant relations are found, with one being a correlation between the unsigned magnetic flux and rotation period. We attribute this to a signature of star-disc interaction, rather than being driven by the dynamo., Comment: 15 pages, 7 figures. Accepted to MNRAS
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- 2014
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12. A high-resolution spectropolarimetric survey of Herbig Ae/Be stars - I. Observations and measurements
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Alecian, E., Wade, G. A., Catala, C., Grunhut, J. H., Landstreet, J. D., Bagnulo, S., Böhm, T., Folsom, C. P., Marsden, S., and Waite, I.
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Astrophysics - Solar and Stellar Astrophysics - Abstract
This is the first in a series of papers in which we describe and report the analysis of a large survey of Herbig Ae/Be stars in circular spectropolarimetry. Using the ESPaDOnS and Narval high-resolution spectropolarimeters at the Canada-France-Hawaii and Bernard Lyot Telescopes, respectively, we have acquired 132 circularly-polarised spectra of 70 Herbig Ae/Be stars and Herbig candidates. The large majority of these spectra are characterised by a resolving power of about 65,000, and a spectral coverage from about 3700 ang to 1 micron. The peak SNR per CCD pixel ranges from below 100 (for the faintest targets) to over 1000 (for the brightest). The observations were acquired with the primary aim of searching for magnetic fields in these objects. However, our spectra are suitable for a variety of other important measurements, including rotational properties, variability, binarity, chemical abundances, circumstellar environment conditions and structure, etc. In this first paper, we describe the sample selection, the observations and their reduction, and the measurements that will comprise the basis of much of our following analysis. We describe the determination of fundamental parameters for each target. We detail the Least-Squares Deconvolution that we have applied to each of our spectra, including the selection, editing and tuning of the LSD line masks. We describe the fitting of the LSD Stokes I profiles using a multi-component model that yields the rotationally-broadened photospheric profile (providing the projected rotational velocity and radial velocity for each observation) as well as circumstellar emission and absorption components. Finally, we diagnose the longitudinal Zeeman effect via the measured circular polarisation, and report the longitudinal magnetic field and Stokes V Zeeman signature detection probability. As an appendix, we provide a detailed review of each star observed., Comment: Accepted for publication in MNRAS, 55 pages, 75 figures
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- 2012
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13. Discovery of a magnetic field in the early B-type star sigma Lupi
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Henrichs, H. F., Kolenberg, K., Plaggenborg, B., Marsden, S. C., Waite, I. A., Landstreet, J. D., Wade, G. A., Grunhut, J. H., Oksala, M. E., and Collaboration, the MiMeS
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Astrophysics - Solar and Stellar Astrophysics - Abstract
Magnetic early B-type stars are rare. To identify them, we use the strongest indirect indicator of a magnetic field in B stars, which is periodic variability of UV stellar wind lines occurring symmetric about the approximate rest wavelength. Probable magnetic candidates are targets for follow-up spectropolarimetry to search for a magnetic field. From the UV wind line variability the B1/B2V star sigma Lupi emerged as a new magnetic candidate star. AAT spectropolarimetric measurements with SEMPOL were obtained. The longitudinal component of the magnetic field integrated over the visible surface of the star was determined with the Least-Squares Deconvolution method. The UV line variations of sigma Lupi are similar to what is known in magnetic B stars, but no periodicity could be determined. We detected a varying longitudinal magnetic field with amplitude of about 100 G with error bars of typically 20 G, which supports an oblique magnetic-rotator configuration. The EW variations of the UV lines, the magnetic and the optical-line variations are consistent with the photometric period of 3.02 d, which we identify with the rotation period of the star. Additional observations with ESPaDOnS attached to the CFHT confirmed this discovery, and allowed the determination of a precise magnetic period. Analysis revealed that sigma Lupi is a He-strong star, with an enhanced N abundance and an underabundance of C, and has a chemically spotted surface. Like in other magnetic B stars the UV wind emission appears to originate close to the magnetic equatorial plane, with maximum emission when a magnetic pole points towards the Earth. The 3.01972(43) d magnetic rotation period is consistent with the photometric period, with maximum light corresponding to maximum magnetic field., Comment: 12 pages, 9 figures
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- 2012
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14. Chemical abundances of magnetic and non-magnetic Herbig Ae/Be stars
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Folsom, C. P., Bagnulo, S., Wade, G. A., Alecian, E., Landstreet, J. D., Marsden, S. C., and Waite, I. A.
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Astrophysics - Solar and Stellar Astrophysics - Abstract
The photospheres of about 10-20% of main sequence A- and B-type stars exhibit a wide range of chemical peculiarities, often associated with the presence of a magnetic field. It is not exactly known at which stage of stellar evolution these chemical peculiarities develop. To investigate this issue, in this paper we study the photospheric compositions of a sample of Herbig Ae and Be stars, which are considered to be the pre-main sequence progenitors of A and B stars. We have performed a detailed abundance analysis of 20 Herbig stars (three of which have confirmed magnetic fields), and one dusty young star. We have found that half the stars in our sample show lambda Boo chemical peculiarities to varying degrees, only one star shows weak Ap/Bp peculiarities, and all the remaining stars are chemically normal. The incidence of lambda Boo chemical peculiarities we find in Herbig stars is much higher than what is seen on the main sequence. We argue that a selective accretion model for lambda Boo star formation is a natural explanation for the remarkably large number of lambda Boo stars in our sample. We also find that the magnetic Herbig stars do not exhibit a range of chemical compositions remarkably different from the normal stars: one magnetic star displays lambda Boo chemical peculiarities (HD 101412), one displays weak Ap/Bp peculiarities (V380 Ori A), and one (HD 190073) is chemically normal. This is completely different from what is seen on the main sequence, where all magnetic A and cool B stars show Ap/Bp chemical peculiarities, and this is consistent with the idea that the magnetic field precedes the formation of the chemical peculiarities typical of Ap and Bp stars., Comment: Accepted for publication in MNRAS, 35 pages, 29 figures
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- 2012
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15. Discovery of the magnetic field of the B1/B2V star \sigma Lupi
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Henrichs, H. F., Kolenberg, K., Plaggenborg, B., Marsden, S. C., Waite, I. A., Landstreet, J., Grunhut, J., Oksala, M., Wade, G., and Collaboration, the MiMeS
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Astrophysics - Solar and Stellar Astrophysics - Abstract
In our search for new magnetic massive stars we use the strongest indirect indicator of a magnetic field in B stars, which is periodic variability of UV stellar wind lines occurring in a velocity range symmetric around zero. Our aim is to obtain follow-up spectropolarimetry to search for a magnetic field in magnetic candidate stars. We quantify UV wind line variability, and analyse its time behaviour. The B1/B2V star sigma Lup emerged as a new magnetic candidate star. AAT spectropolarimetric measurements with SEMPOL were obtained. The stellar wind line variations of sigma Lup are similar to what is known in magnetic B stars, but no periodicity could be determined. We detected a longitudinal magnetic field with varying strength and amplitude of about 100 G with error bars of typically 20 G, which supports an oblique magnetic-rotator configuration. The equivalent width variations of the UV lines, the magnetic and the optical line variations are consistent with the well-known photometric period of 3.02 days, which we identify with the rotation period of the star. Additional observations with ESPaDOnS at CFHT strongly confirmed this discovery, and allowed to determine a precise magnetic period. Further analysis revealed that $\sigma$ Lupi is a helium-strong star, with an enhanced nitrogen abundance and an underabundance of carbon, and has a spotted surface. We conclude that sigma Lup is a magnetic oblique rotator, and is a He-strong star. It is the 4th B star for which a magnetic field is discovered from studying only its wind variability. Like in the other magnetic B stars the wind emission originates in the magnetic equator, with maximum emission occurring when a magnetic pole points towards the Earth. The 3.02 d magnetic rotation period is consistent with the photometric period, with maximum light corresponding to maximum magnetic field. A full paper will be submitted to A&A., Comment: 4 pages, 5 figures, to appear in proceedings with AIP. Stellar polarimetry: From birth to death, Eds. Jennifer Hoffman, Barb Whitney, and Jon Bjorkman
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- 2011
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16. Magnetic fields and differential rotation on the pre-main sequence III: The early-G star HD 106506
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Waite, I. A., Marsden, S. C., Carter, B. D., Hart, R., Donati, J. -F., Vélez, J. C. Ramírez, Semel, M., and Dunstone, N.
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Astrophysics - Solar and Stellar Astrophysics - Abstract
We present photometry and spectropolarimetry of the pre-main sequence star HD 106506. A photometric rotational period of ~1.416 +/- 0.133 days has been derived using observations at Mount Kent Observatory (MKO). Spectropolarimetric data taken at the 3.9-m Anglo-Australian Telescope (AAT) were used to derive spot occupancy and magnetic maps of the star through the technique of Zeeman Doppler imaging (ZDI). The resulting brightness maps indicate that HD 106506 displays photospheric spots at all latitudes including a predominant polar spot. Azimuthal and radial magnetic images of this star have been derived, and a significant azimuthal magnetic field is indicated, in line with other active young stars. A solar-like differential rotation law was incorporated into the imaging process. Using Stokes I information the equatorial rotation rate, $\Omega_{eq}$, was found to be 4.54 +/- 0.01 rad/d, with a photospheric shear $\delta\Omega$ of $0.21_{-0.03}^{+0.02}$ rad/d. This equates to an equatorial rotation period of ~1.39 +/- 0.01 days, with the equatorial region lapping the poles every ~$30_{-3}^{+5}$ days. Using the magnetic features, the equatorial rotation rate, $\Omega_{eq}$, was found to be 4.51 +/- 0.01 rad/d, with a photospheric shear $\delta\Omega$ of 0.24 +/- 0.03 rad/d. This differential rotation is approximately 4 times that observed on the Sun., Comment: 13 pages, 14 figures, accepted by MNRAS
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- 2011
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17. Magnetic fields and differential rotation on the pre-main sequence II: The early-G star HD 141943 - coronal magnetic field, H-alpha emission and differential rotation
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Marsden, S. C., Jardine, M. M., Vélez, J. C. Ramírez, Alecian, E., Brown, C. J., Carter, B. D., Donati, J. F., Dunstone, N., Hart, R., Semel, M., and Waite, I. A.
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Astrophysics - Solar and Stellar Astrophysics - Abstract
Spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at three observing epochs (2007, 2009 and 2010). The observations were obtained using the 3.9-m Anglo-Australian telescope with the UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor instrument. The brightness and surface magnetic field topologies (given in Paper I) were used to determine the star's surface differential rotation and reconstruct the coronal magnetic field of the star. The coronal magnetic field at the 3 epochs shows on the largest scales that the field structure is dominated by the dipole component with possible evidence for the tilt of the dipole axis shifting between observations. We find very high levels of differential rotation on HD 141943 (~8 times the solar value for the magnetic features and ~5 times solar for the brightness features) similar to that evidenced by another young early-G star, HD 171488. These results indicate that a significant increase in the level of differential rotation occurs for young stars around a spectral type of early-G. Also we find for the 2010 observations that there is a large difference in the differential rotation measured from the brightness and magnetic features, similar to that seen on early-K stars, but with the difference being much larger. We find only tentative evidence for temporal evolution in the differential rotation of HD 141943., Comment: 11 pages, 7 figures, accepted by MNRAS
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- 2011
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18. Magnetic fields and differential rotation on the pre-main sequence I: The early-G star HD 141943 - brightness and magnetic topologies
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Marsden, S. C., Jardine, M. M., Vélez, J. C. Ramírez, Alecian, E., Brown, C. J., Carter, B. D., Donati, J. F., Dunstone, N., Hart, R., Semel, M., and Waite, I. A.
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Astrophysics - Solar and Stellar Astrophysics - Abstract
Spectroscopic and spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at four observing epochs (in 2006, 2007, 2009 and 2010). The observations were undertaken at the 3.9-m Anglo-Australian Telescope using the UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor instrument. Brightness and surface magnetic field topologies were reconstructed for the star using the technique of least-squares deconvolution to increase the signal-to-noise of the data. The reconstructed brightness maps show that HD 141943 had a weak polar spot and a significant amount of low latitude features, with little change in the latitude distribution of the spots over the 4 years of observations. The surface magnetic field was reconstructed at three of the epochs from a high order (l <= 30) spherical harmonic expansion of the spectropolarimetric observations. The reconstructed magnetic topologies show that in 2007 and 2010 the surface magnetic field was reasonably balanced between poloidal and toroidal components. However we find tentative evidence of a change in the poloidal/toroidal ratio in 2009 with the poloidal component becoming more dominant. At all epochs the radial magnetic field is predominantly non-axisymmetric while the azimuthal field is predominantly axisymmetric with a ring of positive azimuthal field around the pole similar to that seen on other active stars., Comment: 18 pages, 17 figures, accepted by MNRAS
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- 2011
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19. Discovery of the magnetic field in the B1/B2V star sigma Lupi
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Henrichs, H. F., Kolenberg, K., Plaggenborg, B., Marsden, S. C., Waite, I. A., Wade, G., and Collaboration, the MiMeS
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Astrophysics - Solar and Stellar Astrophysics - Abstract
The ultraviolet stellar wind lines of the photometrically periodic variable early B-type star sigma Lupi were found to behave very similarly to what has been observed in known magnetic B stars, although no periodicity could be determined. AAT spectropolarimetric measurements with SEMPOL were obtained. We detected a longitudinal magnetic field with varying strength and amplitude of about 100 G with error bars of typically 20 G. This type of variability supports an oblique magnetic rotator model. We fold the equivalent width of the 4 usable UV spectra in phase with the well-known photometric period of 3.019 days, which we identify with the rotation period of the star. The magnetic field variations are consistent with this period. Additional observations with ESPaDOnS attached to the CFHT strongly confirmed this discovery, and allowed to determine a precise magnetic period. Like in the other magnetic B stars the wind emission likely originates in the magnetic equatorial plane, with maximum emission occurring when a magnetic pole points towards the Earth. The 3.0182 d magnetic rotation period is consistent with the photometric period, with maximum light corresponding to maximum magnetic field. No helium or other chemical peculiarity is known for this object., Comment: 2 pages, 2 figures, to appear in the proceedings of IAU Symposium 272, Active OB stars - structure, evolution, mass loss, and critical limits
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- 2010
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20. Evolution of brightness and magnetic features of young solar-type stars II: The young F8 star HIP 71933
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Hughes, J E, primary, Marsden, S C, additional, Carter, B D, additional, Waite, I A, additional, Burton, D M, additional, Perugini, G M, additional, and Hébrard, E M, additional
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- 2023
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21. Target and suspect per- and polyfluoroalkyl substances in fish from an AFFF-impacted waterway.
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Nilsen E, Muensterman D, Carini L, Waite I, Payne S, Field JA, Peterson J, Hafley D, Farrer D, and Jones GD
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- Animals, Water, Water Pollutants, Chemical analysis, Fluorocarbons analysis, Bass, Cypriniformes, Alkanesulfonic Acids analysis
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A major source of toxic per- and polyfluoroalkyl substances (PFAS) is aqueous film-forming foams (AFFF) used in firefighting and training at airports and military installations, however, PFAS have many additional sources in consumer products and industrial processes. A field study was conducted on fish tissues from three reaches of the Columbia Slough, located near Portland International Airport, OR, that are affected by AFFF and other PFAS sources. Fishes including largescale sucker (Catostomus macrocheilus), goldfish (Carassius auratus), and largemouth bass (Micropterus salmoides) were collected in 2019 and 2020. Fish blood, liver, and fillet (muscle) were analyzed for target and suspect PFAS by liquid chromatography high resolution mass spectrometry (LC-HRMS). Data were analyzed for patterns by fish species, tissue type, and river reach. Thirty-three out of 50 target PFAS and additional suspect compounds were detected at least once during the study, at concentrations up to 856 ng/g. Seven carboxylic acids (PFOA, PFNA, PFDA, PFUdA, PFDoA, PFTrDA, PFTeDA), three sulfonates (PFHxS, PFOS, PFDS), three electrofluorination-based compounds (FBSA, FHxSA, FOSA), and two fluorotelomer-based compounds (8:2 FTS, 10:2 FTS) were the most frequently detected compounds in all tissue types. The C6 (PFHxS) to C10 (PFDS) homologs were detected with PFOS and FHxSA at concentrations 1-3 orders of magnitude greater than the other PFAS detected. This is the first report of Cl-PFOS, FPeSA, and FHpSA detected in fish tissue. In all fish samples, fillet concentrations of PFAS were the lowest, followed by liver, and blood concentrations of PFAS were the highest. Differences in PFAS concentrations were driven primarily by tissue types and to a lesser extent fish species, but weakly by river reach. The Oregon Health Authority modified an existing fish consumption advisory on the Columbia Slough to recommend no whole-body consumption of most fish to avoid elevated levels of PFOS in fish liver. Measured PFAS concentrations in fish tissues indicate the potential for adverse ecological effects., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier B.V.)
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- 2024
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22. Multisite, Multiwavelength Studies of the Active Cool Binary CC Eri
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Budding, E., Erkan, N., Bembrick, C., Carter, B. D., Waite, I., Jardine, M., Marsden, S. C., Osten, R., Petit, P., Semel, M., Slee, O. B., Giménez, Àlvaro, editor, Guinan, Edward, editor, Niarchos, Panagiotis, editor, and Rucinski, Slavek, editor
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- 2006
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23. Morbidity and mortality following heart failure rehabilitation: The effect of programme completion and 6-min walk test distance.
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Waite I, Pearson C, and Greenwood S
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- Humans, Male, Walk Test, Retrospective Studies, Morbidity, Cardiac Rehabilitation methods, Heart Failure diagnosis, Heart Failure rehabilitation
- Abstract
Objective: To compare real-world data from a single centre heart failure rehabilitation programme, evaluating the effect of programme completion and improved functional capacity on morbidity and mortality in patients with heart failure., Design: A retrospective longitudinal analysis of service outcomes., Setting: A single-centre London based NHS trust., Participants: Patients attending heart failure rehabilitation between 2016 and 2020., Intervention: Patients participated in a 12-week heart failure rehabilitation programme with those completing ≥6 rehabilitation sessions classified as 'completers'., Main Measures: Pre and post 6-min walk tests measured improvement in physical ability, depicted by a meaningful increase in distance (≥30 m). Kaplan-Meier survival analysis was used to predict risk of event (myocardial infarction, cerebrovascular accident, heart failure readmission and death) between 'completers' and 'non-completers'. Kaplan-Meier Log rank was employed for 'completers', examining time to event between 'improvers' (6-min walk test ≥30 m) and 'non-improvers' (6-min walk test <30 m)., Results: 137 patients (male 61%) attended heart failure rehabilitation over the 4-year period. 86% ( n = 117) of patients completed the programme. During the follow-up period, there were 25 events, including three deaths. There was no statistically significant difference in time to event between completers and non-completers, ( P = 0.563). Improvement in 6-min walk test results demonstrate some short-term benefit, however no long-term benefits in morbidity and mortality were seen ( P = 0.888)., Conclusions: Completion of heart failure rehabilitation is not associated with a lower risk of combined event in this study. Improved 6-min walk test appears to be associated with short-term advantage in event-free survival time.
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- 2023
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24. Pathways to the therapist paragon: a decolonial grounded theory.
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Bergkamp J, O'Leary Sloan M, Krizizke J, Lash M, Trantel N, Vaught J, Fulmer T, Waite I, Martin AM, Scheiderer C, and Olson L
- Abstract
Introduction: While many professional associations within clinical and counseling psychology have made an aspirational call for clinician awareness of social position, there is a lack of research into how socially-conferred privilege impacts psychotherapy. Specifically of interest is the differences in race and gender within the therapeutic dyad, in which there is a BIPOC (Black, Indigenous, and Persons of Color)/white or male/female-identified dynamic., Method: The authors utilized a Grounded Theory approach to analyze qualitative interviews with practicing psychologists to construct a process model regarding how socially-conferred privileged identity domains impact the therapeutic relationship and the participants' professionalization process., Results: The analysis identified the core conceptual theme of the Therapist Paragon, representing an idealized version of what a perfect therapist should be. This replicated the foundational figures of our field - primarily older, white men. The process model consisted of two distinct pathways toward the Therapist Paragon, one for BIPOC psychologists and one for white psychologists. The female BIPOC pathway consisted of imposter syndrome, persistent feelings of inadequacy, and tendencies to over-credential their professional identity to seek credibility in the eyes of clients and colleagues. The white pathway consisted of down-playing whiteness and attempting to initially modify behavior toward client cultural norms., Discussion: The results point to a distinct professionalization and practice process for BIPOC psychologists compared to white counterparts. This dynamic may have implications beyond increasing support for BIPOC clinicians specifically, but instead indicate a lack of acknowledgement of the psychological impact of socially-conferred privilege in the psychotherapy enterprise overall. Recommendations are offered for revisions to training models, continuing education, and supervision/consultation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Bergkamp, O’Leary Sloan, Krizizke, Lash, Trantel, Vaught, Fulmer, Waite, Martin, Scheiderer and Olson.)
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- 2023
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25. Evaluating the impact of the COVID-19 pandemic on the delivery and efficiency of cardiac rehabilitation.
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Kilner N, Greenwood S, Cable J, and Waite I
- Abstract
The SARS-CoV-2 (COVID-19) pandemic brought disruption to cardiac rehabilitation (CR) services in the UK, requiring innovation and use of remote interventions. This retrospective longitudinal study compares single-centre CR service data across three time periods: 'pre' (June 2019 to December 2019), 'during' (January 2020 to May 2020) and 'post' (June 2020 to December 2020), evaluating adaptations in programme delivery and subsequent effect on efficiency. There were 614 patients (72.7% male) identified between June 2019 and December 2020. Eligible CR referrals reduced 30.3% and encountered >50% decrease in engagement 'during' the pandemic, compared with 'pre' pandemic. The 'post' pandemic hybrid redesign led to a significant reduction in hospital discharge to CR contact (mean 5.39 days, p=0.001), and time spent in CR (41.33 days, p=0.001) when compared with 'pre' and 'during' figures. CR engagement significantly increased 'post' pandemic for ST-elevation myocardial infarction (STEMI)/non-STEMI (NSTEMI)/acute coronary syndrome (ACS) (56%, p=0.02) and 'post' cardiac surgery (76%, p=0.015). Referrals to cardiac psychology increased >50% 'post' pandemic (7.8%, p=0.038). A 'post' pandemic hybrid CR programme is effective at reducing wait times, increasing engagement and reducing time to completion of CR, compared with 'pre' and 'during' pandemic figures. A significant increase in cardiac psychology referrals 'post' pandemic highlights the importance of psychology support within CR., Competing Interests: Conflicts of interest None declared., (Copyright © 2023 Medinews (Cardiology) Limited.)
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- 2023
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26. Evolution of brightness and magnetic features of young solar-type stars – I. The young G star HIP 89829
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Perugini, G M, primary, Marsden, S C, additional, Waite, I A, additional, Jeffers, S V, additional, Piskunov, N, additional, Shaw, N, additional, Burton, D M, additional, Mengel, M W, additional, Hughes, J E, additional, and Hébrard, E M, additional
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- 2021
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27. Planets around young active solar-type stars: assessing detection capabilities from a non-stabilized spectrograph
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Heitzmann, A, primary, Marsden, S C, additional, Petit, P, additional, Mengel, M W, additional, Wright, D, additional, Clerte, M, additional, Millburn, I, additional, Folsom, C P, additional, Addison, B C, additional, Wittenmyer, R A, additional, and Waite, I A, additional
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- 2021
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28. Evolution of brightness and magnetic features of young solar-type stars - I. The young G star HIP 89829
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Perugini, G. M., Marsden, S. C., Waite, I. A., Jeffers, S. , V, Piskunov, Nikolai, Shaw, N., Burton, D. M., Mengel, M. W., Hughes, J. E., Hebrard, E. M., Perugini, G. M., Marsden, S. C., Waite, I. A., Jeffers, S. , V, Piskunov, Nikolai, Shaw, N., Burton, D. M., Mengel, M. W., Hughes, J. E., and Hebrard, E. M.
- Abstract
The evolution in latitude of sunspots is a key feature of the cyclic solar dynamo. Here, we present the results of a spectroscopic and spectropolarimetric monitoring campaign on the young (similar to 20 Myr old) early G star HIP 89829, in order to investigate potential evolution in the distribution of the star's spots and magnetic features. Our analysis of this G5V star spans eight epochs, from June 2010 to August 2015. The techniques of Doppler imaging and Zeeman-Doppler imaging were used to create brightness maps for each epoch and magnetic maps for two epochs. The brightness images show the star to have stable spot features with two main spot latitudes - a polar spot, often seen on young rapidly rotating stars such as this, and another highly unusual group of large spot features around the 20 degrees and 30 degrees latitudes. These lower spot latitudes appear to be rather stable over the 5 yr of observations. We included a solar-type differential rotation law into the imaging process and measured near-solid-body rotation for epochs where sufficient data exist for this analysis. The magnetic features show a dominant poloidal and a weaker toroidal magnetic field for both Stokes V epochs, which is unusual for a star with a rapid rotation period of 0.57 d. We conclude that HIP 89829 is an active young solar-type star with long-lived spots and near-solid-body rotation.
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- 2021
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29. Treatment of Periodontal Disease : A Controlled Longitudinal Study into the Effectiveness of Conventional Gingivectomy
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Waite, I. M.
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617.6 - Published
- 1976
30. Home-based Preoperative Rehabilitation (PREHAB) to improve physical function and reduce hospital length of stay for frail patients undergoing cardiac surgery
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Waite, I., primary, Massey, T., additional, Baghai, M., additional, Wendler, O., additional, Deshpande, R., additional, and Greenwood, S., additional
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- 2017
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31. The energy budget of stellar magnetic fields
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See, V., Jardine, M., Vidotto, A. A., Donati, J.-F, Folsom, C. P., Boro Saikia, S., Bouvier, J., Fares, R., Gregory, S. G., Hussain, G., Jeffers, S. V., Marsden, S. C., Morin, J., Moutou, C., do Nascimento, J. D., Petit, P., Rosén, L., Waite, I. A., See, V., Jardine, M., Vidotto, A. A., Donati, J.-F, Folsom, C. P., Boro Saikia, S., Bouvier, J., Fares, R., Gregory, S. G., Hussain, G., Jeffers, S. V., Marsden, S. C., Morin, J., Moutou, C., do Nascimento, J. D., Petit, P., Rosén, L., and Waite, I. A.
- Abstract
Spectropolarimetric observations have been used to map stellar magnetic fields, many of which display strong bands of azimuthal fields that are toroidal. A number of explanations have been proposed to explain how such fields might be generated though none are definitive. In this paper, we examine the toroidal fields of a sample of 55 stars with magnetic maps, with masses in the range 0.1-1.5 M⊙. We find that the energy contained in toroidal fields has a power-law dependence on the energy contained in poloidal fields. However the power index is not constant across our sample, with stars less and more massive than 0.5 M⊙ having power indices of 0.72±0.08 and 1.25±0.06, respectively. There is some evidence that these two power laws correspond to stars in the saturated and unsaturated regimes of the rotation-activity relation. Additionally, our sample shows that strong toroidal fields must be generated axisymmetrically. The latitudes at which these bands appear depend on the stellar rotation period with fast rotators displaying higher latitude bands than slow rotators. The results in this paper present new constraints for future dynamo studies
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- 2017
32. What can we Learn About Stellar Activity Cycles from ZDI?
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See, Victor, Jardine, M., Vidotto, A., Donati, J.-F., Boro Saikia, S., Bouvier, J., Fares, R., Folsom, C., Gregory, S., Hussain, G., Jeffers, S., Marsden, S., Morin, J., Moutou, C., do Nascimento, J. D., Petit, P., Waite, I., +BCool Collaboration, Feiden, Gregory, Fabbian, Damian, Simoniello, Rosaria, Collet, Remo, Criscuoli, Serena, Korhonen, Heidi, Krivova, Natalie, Oláh, Katalin, Shapiro, Alexander, Vidotto, Aline, Vitas, Nikola, Science & Technology Facilities Council, and University of St Andrews. School of Physics and Astronomy
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QC Physics ,QB Astronomy ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,QC ,QB - Abstract
It is known that activity cycles, similar to the 11 year cycle of the Sun, can exist on other stars. Previous work suggests that stars may lie on two branches in a cycle period vs rotation period diagram though there is no definitive explanation for why this should be the case.Fundamentally, activity cycles occur as a result of the underlying dynamo. Indeed, a great deal has been learnt about the Sun's activity cycle by studying how its magnetic field evolves over each activity cycle. In the same way, we should be able to learn about the activity cycles of other stars by studying their magnetic field properties. In this talk, I will present new insights into stellar activity cycles by analysing the magnetic maps of stars that are known to present activity cycles. I will show that stars along each of the branches appear to have different magnetic field topologies. Publisher PDF
- Published
- 2016
- Full Text
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33. Assessing the suitability of microalgae biomass produced from piggery waste as a fertiliser
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Jenkins, S. N., primary, Paredes-Valdivia, C. A., additional, Waite, I. S., additional, Ayre, J., additional, Moheimani, N., additional, Barton, L., additional, and Abbott, L. K., additional
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- 2017
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34. Long-term evolution of the large-scale magnetic fields of cool stars
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Vidotto, A. a., Gregory, S. G., Jardine, M., Donati, J. -F., Petit, P., MORIN, Julien, Folsom, C. P., Bouvier, J., Cameron, A. C., Hussain, G., Marsden, S., Waite, I. a., Fares, R., Jeffers, S. V., Do Nascimento, J.D. Jr, Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), University of St Andrews [Scotland], University of St Andrews, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Laboratoire Univers et Particules de Montpellier (LUPM), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), ESO Garching, University of Southern Queensland (USQ), INAF - Osservatorio Astrofisico di Catania (OACT), Istituto Nazionale di Astrofisica (INAF), Institut für Astrophysik [Göttingen], Georg-August-University [Göttingen], Universidade Federal do Rio Grande do Norte [Natal] (UFRN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
We investigate how the large-scale surface magnetic fields of cool dwarf stars, reconstructed using the Zeeman-Doppler Imaging (ZDI) technique, vary with age, rotation period, Rossby number and X-ray emission. Our sample consists of 104 magnetic maps of 76 stars, from accreting pre-main sequence to main-sequence objects, spanning ages from ~1 Myr to ~10 Gyr. For non-accreting dwarfs we empirically find that the unsigned average large-scale surface magnetic field relates to age as age-0.65. This relation has a similar power dependency to that identified in the seminal work of Skumanich (1972). We also find in our data evidence for a linear-type dynamo, in which the surface field is linearly dependent on the rotation rate. The trends we find for large-scale stellar magnetism from ZDI studies are consistent with the trends found from Zeeman broadening measurements, which are sensitive to the unsigned large- and small-scale magnetic field. These similarities indicate that the fields recovered from both techniques are coupled to each other, suggesting that small- and large-scale fields could share the same dynamo field generation processes. Our results are relevant for investigations of rotational evolution of low-mass stars and give important observational constraints for stellar dynamo studies.
- Published
- 2015
35. Doppler images and the underlying dynamo
- Author
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Järvinen, S. P., Arlt, R., Hackman, T., Marsden, S. C., Küker, M., Ilyin, I. V., Berdyugina, S. V., Strassmeier, K. G., and Waite, I. A.
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- 2015
- Full Text
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36. Microbial phylogenetic and functional responses within acidified wastewater communities exhibiting enhanced phosphate uptake
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Weerasekara, A., Jenkins, S., Abbott, L., Waite, I., McGrath, J., Larma, I., Eroglu, Ela, O'Donnell, A., Whiteley, A., Weerasekara, A., Jenkins, S., Abbott, L., Waite, I., McGrath, J., Larma, I., Eroglu, Ela, O'Donnell, A., and Whiteley, A.
- Abstract
Acid stimulated accumulation of insoluble phosphorus within microbial cells is highly beneficial to wastewater treatment but remains largely unexplored. Using single cell analyses and next generation sequencing, the response of active polyphosphate accumulating microbial communities under conditions of enhanced phosphorus uptake under both acidic and aerobic conditions was characterised. Phosphorus accumulation activities were highest under acidic conditions (pH 5.5>8.5), where a significant positive effect on bioaccumulation was observed at pH 5.5 when compared to pH 8.5. In contrast to the Betaproteobacteria and Actinobacteria dominated enhanced biological phosphorus removal process, the functionally active polyP accumulators at pH 5.5 belonged to the Gammaproteobacteria, with key accumulators identified as members of the families Aeromonadaceae and Enterobacteriaceae. This study demonstrated a significant enrichment of key polyphosphate kinase and exopolyphosphatase genes within the community metagenome after acidification, concomitant with an increase in P accumulation kinetics.
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- 2016
37. Erratum.
- Author
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Greenwood SA, Castle E, Lindup H, Mayes J, Waite I, Grant D, Mangahis E, Crabb O, Shevket K, Macdougall IC, and MacLaughlin HL
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- 2020
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38. The connection between stellar activity cycles and magnetic field topology
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See, V., primary, Jardine, M., additional, Vidotto, A. A., additional, Donati, J.-F., additional, Boro Saikia, S., additional, Bouvier, J., additional, Fares, R., additional, Folsom, C. P., additional, Gregory, S. G., additional, Hussain, G., additional, Jeffers, S. V., additional, Marsden, S. C., additional, Morin, J., additional, Moutou, C., additional, do Nascimento, J. D., additional, Petit, P., additional, and Waite, I. A., additional
- Published
- 2016
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39. Discovery of the magnetic field of the B1/B2V star ��Lupi
- Author
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Henrichs, H. F., Kolenberg, K., Plaggenborg, B., Marsden, S. C., Waite, I. A., Landstreet, J., Grunhut, J., Oksala, M., Wade, G., and Collaboration, the MiMeS
- Subjects
Astrophysics::Solar and Stellar Astrophysics ,FOS: Physical sciences ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
In our search for new magnetic massive stars we use the strongest indirect indicator of a magnetic field in B stars, which is periodic variability of UV stellar wind lines occurring in a velocity range symmetric around zero. Our aim is to obtain follow-up spectropolarimetry to search for a magnetic field in magnetic candidate stars. We quantify UV wind line variability, and analyse its time behaviour. The B1/B2V star sigma Lup emerged as a new magnetic candidate star. AAT spectropolarimetric measurements with SEMPOL were obtained. The stellar wind line variations of sigma Lup are similar to what is known in magnetic B stars, but no periodicity could be determined. We detected a longitudinal magnetic field with varying strength and amplitude of about 100 G with error bars of typically 20 G, which supports an oblique magnetic-rotator configuration. The equivalent width variations of the UV lines, the magnetic and the optical line variations are consistent with the well-known photometric period of 3.02 days, which we identify with the rotation period of the star. Additional observations with ESPaDOnS at CFHT strongly confirmed this discovery, and allowed to determine a precise magnetic period. Further analysis revealed that $��$ Lupi is a helium-strong star, with an enhanced nitrogen abundance and an underabundance of carbon, and has a spotted surface. We conclude that sigma Lup is a magnetic oblique rotator, and is a He-strong star. It is the 4th B star for which a magnetic field is discovered from studying only its wind variability. Like in the other magnetic B stars the wind emission originates in the magnetic equator, with maximum emission occurring when a magnetic pole points towards the Earth. The 3.02 d magnetic rotation period is consistent with the photometric period, with maximum light corresponding to maximum magnetic field. A full paper will be submitted to A&A., 4 pages, 5 figures, to appear in proceedings with AIP. Stellar polarimetry: From birth to death, Eds. Jennifer Hoffman, Barb Whitney, and Jon Bjorkman
- Published
- 2011
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40. Magnetic fields and differential rotation on the pre-main sequence - II. The early-G star HD 141943 - coronal magnetic field, Halpha emission and differential rotation
- Author
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Marsden, S. C., Jardine, M. M., V��lez, J. C. Ram��rez, Alecian, E., Brown, C. J., Carter, B. D., Donati, J. F., Dunstone, N., Hart, R., Semel, M., Waite, I. A., Centre for Astronomy, James Cook University, SUPA Physics and Astronomy, University of St Andrews, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Etoile, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Instituto de Astronomia, Universidad Nacional Autonomica de Mexico, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Faculty of Sciences, University of Southern Queensland, Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,FOS: Physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics - Abstract
Spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at three observing epochs (2007, 2009 and 2010). The observations were obtained using the 3.9-m Anglo-Australian telescope with the UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor instrument. The brightness and surface magnetic field topologies (given in Paper I) were used to determine the star's surface differential rotation and reconstruct the coronal magnetic field of the star. The coronal magnetic field at the 3 epochs shows on the largest scales that the field structure is dominated by the dipole component with possible evidence for the tilt of the dipole axis shifting between observations. We find very high levels of differential rotation on HD 141943 (~8 times the solar value for the magnetic features and ~5 times solar for the brightness features) similar to that evidenced by another young early-G star, HD 171488. These results indicate that a significant increase in the level of differential rotation occurs for young stars around a spectral type of early-G. Also we find for the 2010 observations that there is a large difference in the differential rotation measured from the brightness and magnetic features, similar to that seen on early-K stars, but with the difference being much larger. We find only tentative evidence for temporal evolution in the differential rotation of HD 141943., 11 pages, 7 figures, accepted by MNRAS
- Published
- 2011
41. The energy budget of stellar magnetic fields
- Author
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See, V., primary, Jardine, M., additional, Vidotto, A. A., additional, Donati, J.-F., additional, Folsom, C. P., additional, Boro Saikia, S., additional, Bouvier, J., additional, Fares, R., additional, Gregory, S. G., additional, Hussain, G., additional, Jeffers, S. V., additional, Marsden, S. C., additional, Morin, J., additional, Moutou, C., additional, do Nascimento, J. D., additional, Petit, P., additional, Rosén, L., additional, and Waite, I. A., additional
- Published
- 2015
- Full Text
- View/download PDF
42. Magnetic fields on young, moderately rotating Sun-like stars – I. HD 35296 and HD 29615
- Author
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Waite, I. A., primary, Marsden, S. C., additional, Carter, B. D., additional, Petit, P., additional, Donati, J.-F., additional, Jeffers, S. V., additional, and Boro Saikia, S., additional
- Published
- 2015
- Full Text
- View/download PDF
43. Effectiveness of different mitigation strategies to reduce nitrous oxide emissions from pig manure amended soils
- Author
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Jenkins, S. N., primary, Waite, I. S., additional, Mickan, B., additional, and Abbott, L. K., additional
- Published
- 2015
- Full Text
- View/download PDF
44. Relationships between diets different in fibre type and content with growth, Escherichia coli shedding, and faecal microbial diversity after weaning
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Jenkins, S. N., primary, Waite, I. S., additional, Mansfield, J., additional, Kim, J. C., additional, and Pluske, J. R., additional
- Published
- 2015
- Full Text
- View/download PDF
45. Mortality and morbidity following exercise-based renal rehabilitation in patients with chronic kidney disease: the effect of programme completion and change in exercise capacity.
- Author
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Greenwood SA, Castle E, Lindup H, Mayes J, Waite I, Grant D, Mangahis E, Crabb O, Shevket K, Macdougall IC, and MacLaughlin HL
- Subjects
- Female, Humans, Longitudinal Studies, Male, Middle Aged, Morbidity, Prognosis, Program Evaluation, Recovery of Function, Retrospective Studies, Survival Rate, Exercise Therapy mortality, Hospitalization statistics & numerical data, Patient Compliance, Renal Dialysis mortality, Renal Insufficiency, Chronic mortality, Renal Insufficiency, Chronic rehabilitation
- Abstract
Background: Twelve weeks of renal rehabilitation (RR) have been shown to improve exercise capacity in patients with chronic kidney disease (CKD); however, survival following RR has not been examined., Methods: This study included a retrospective longitudinal analysis of clinical service outcomes. Programme completion and improvement in exercise capacity, characterised as change in incremental shuttle walk test (ISWT), were analysed with Kaplan-Meier survival analyses to predict risk of a combined event including death, cerebrovascular accident, myocardial infarction and hospitalisation for heart failure in a cohort of patients with CKD. Time to combined event was examined with Kaplan-Meier plots and log rank test between 'completers' (attended >50% planned sessions) and 'non-completers'. In completers, time to combined event was examined between 'improvers' (≥50 m increase ISWT) and 'non-improvers' (<50 m increase). Differences in time to combined event were investigated with Cox proportional hazards models (adjusted for baseline kidney function, body mass index, diabetes, age, gender, ethnicity, baseline ISWT and smoking status)., Results: In all, 757 patients (male 54%) (242 haemodialysis patients, 221 kidney transplant recipients, 43 peritoneal dialysis patients, 251 non-dialysis CKD patients) were referred for RR between 2005 and 2017. There were 193 events (136 deaths) during the follow-up period (median 34 months). A total of 43% of referrals were classified as 'completers', and time to event was significantly greater when compared with 'non-completers' (P = 0.009). Responding to RR was associated with improved event-free survival time (P = 0.02) with Kaplan-Meier analyses and log rank test. On multivariate analysis, completing RR contributed significantly to the minimal explanatory model relating clinical variables to the combined event (overall χ2 = 38.0, P < 0.001). 'Non-completers' of RR had a 1.6-fold [hazard ratio = 1.6; 95% confidence interval (CI) 1.00-2.58] greater risk of a combined event (P = 0.048). Change in ISWT of >50 m contributed significantly to the minimal explanatory model relating clinical variables to mortality and morbidity (overall χ2 = 54.0, P < 0.001). 'Improvers' had a 40% (hazard ratio = 0.6; 95% CI 0.36-0.98) independent lower risk of a combined event (P = 0.041)., Conclusions: There is an association between completion of an RR programme, and also RR success, and a lower risk of a combined event in this observational study. RR interventions to improve exercise capacity in patients with CKD may reduce risk of morbidity and mortality, and a pragmatic randomised controlled intervention trial is warranted., (© The Author(s) 2018. Published by Oxford University Press on behalf of ERA-EDTA.)
- Published
- 2019
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46. Relationships between diatom metrics based on species nutrient traits and agricultural land use.
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Pillsbury R, Stevenson RJ, Munn MD, and Waite I
- Subjects
- Environmental Monitoring standards, Nitrogen analysis, Phosphorus analysis, Rivers, Wetlands, Agriculture, Diatoms physiology, Environmental Monitoring methods
- Abstract
We assessed how diatom metrics were related to different ranges of agricultural land use. Diatom assemblage composition, nutrients, and landscape characteristics were determined at 232 sites in eight agriculturally dominated study areas of the continental United States. Two regional groups based on differences in diatom relations to human disturbance were determined. Changes in diatom species composition were related to nutrients, pH, and conductivity in the eastern study areas (due to more wetlands) and more exclusively to nutrients in the west-central study areas. Homogenization of diatom flora among streams was related to high agricultural disturbance at this transcontinental scale. Species traits were developed separately for the east and west-central study groups and calculated two ways: indicator species analysis for taxa in low and high TN or TP conditions and weighted average partial least squares models of TN and TP concentration. These diatom metrics were significantly related to many indicators of agricultural land use in watersheds, especially percent row crops. Further analysis was conducted on only the west-central region due to its larger sample size. Overall, diatom metrics using species responses to N gradients were better related to agricultural land use than were species responses to P gradients. Most nutrient-based diatom metrics changed greatly in response to low ranges of percent row crops, but only a few high N diatom metrics responded to high row crop conditions. The greater response of diatoms to changes in low agriculture conditions may be due to past diatom evolution occurring when most waters had low nutrient conditions.
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- 2019
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47. RNA Stable Isotope Probing (RNA-SIP).
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Ghori NU, Moreira-Grez B, Vuong P, Waite I, Morald T, Wise M, and Whiteley AS
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- Carbon Isotopes chemistry, Centrifugation, Density Gradient instrumentation, Centrifugation, Density Gradient methods, DNA, Bacterial genetics, DNA, Bacterial metabolism, Microbiota genetics, RNA isolation & purification, RNA metabolism, RNA Probes genetics, RNA, Ribosomal, 16S metabolism, Spectrum Analysis, Raman, Workflow, Isotope Labeling methods, RNA Probes metabolism
- Abstract
Stable isotope probing is a combined molecular and isotopic technique used to probe the identity and function of uncultivated microorganisms within environmental samples. Employing stable isotopes of common elements such as carbon and nitrogen, RNA-SIP exploits an increase in the buoyant density of RNA caused by the active metabolism and incorporation of heavier mass isotopes into the RNA after cellular utilization of labeled substrates pulsed into the community. Labeled RNAs are subsequently separated from unlabeled RNAs by density gradient centrifugation followed by identification of the RNAs by sequencing. Therefore, RNA stable isotope probing is a culture-independent technique that provides simultaneous information about microbiome community, composition and function. This chapter presents the detailed protocol for performing an RNA-SIP experiment, including the formation, ultracentrifugation, and fractional analyses of stable isotope-labeled RNAs extracted from environmental samples.
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- 2019
- Full Text
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48. Magnetic fields on young, moderately rotating Sun-like stars - II. EK Draconis (HD 129333).
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Waite, I. A., Marsden, S. C., Carter, B. D., Petit, P., Jeffers, S. V., Morin, J., Vidotto, A. A., and Donati, J.-F.
- Subjects
- *
COSMIC magnetic fields , *STELLAR rotation , *ASTROPHYSICAL spectropolarimetry , *DOPPLER effect , *ZEEMAN effect - Abstract
The magnetic fields, activity and dynamos of young solar-type stars can be empirically studied using time series of spectropolarimetric observations and tomographic imaging techniques such as Doppler imaging and Zeeman-Doppler imaging. In this paper, we use these techniques to study the young Sun-like star EK Draconis (SpType: G1.5V, HD 129333) using ESPaDOnS at the Canada-France-Hawaii Telescope and NARVAL at the Télescope Bernard Lyot. This multi-epoch study runs from late 2006 until early 2012. We measure high levels of chromospheric activity indicating an active, and varying, chromosphere. Surface brightness features were constructed for all available epochs. The 2006/2007 and 2008 data show large spot features appearing at intermediate latitudes. However, the 2012 data indicate a distinctive polar spot. We observe a strong, almost unipolar, azimuthal field during all epochs, which is similar to that observed on other Sun-like stars. Using magnetic features, we determined an average equatorial rotational velocity, Ωeq, of ~2.50±0.08 rad d-1. High levels of surface differential rotation were measured with an average rotational shear, ΔΩ, of ~0.27-0.26+0.24 rad d-1. During an intensively observed 3-month period, from 2006 December until 2007 February, the magnetic field went from predominantly toroidal (~80 per cent) to a more balanced poloidal-toroidal (~40-60 per cent) field. Although the large-scale magnetic field evolved over the epochs of our observations, no polarity reversals were found in our data. [ABSTRACT FROM AUTHOR]
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- 2017
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49. Doppler imaging and surface differential rotation of young open cluster stars: I. HD 307938 (R58) in IC 2602
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Marsden, S. C., Waite, I. A., Carter, B. D., and Donati, J.-F
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Stars : imaging ,Stars : rotation ,Stars : individual : HD 307938 ,activity ,Stars : late-type ,Stars : rotation [Stars] ,Stars : activity - Abstract
Monthly Notices of the Royal Astronomical Society, 359 (2), ISSN:0035-8711, ISSN:1365-2966, ISSN:1365-8711
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- 2005
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50. Multisite, Multiwavelength Studies of the Active Cool Binary CC Eri
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Budding, E., primary, Erkan, N., additional, Bembrick, C., additional, Carter, B. D., additional, Waite, I., additional, Jardine, M., additional, Marsden, S. C., additional, Osten, R., additional, Petit, P., additional, Semel, M., additional, and Slee, O. B., additional
- Full Text
- View/download PDF
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