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  • 1
    Electronic Resource
    Electronic Resource
    Brattleboro rat adrenal contains vasopressin (1984)
    [s.l.] : Nature Publishing Group
    Nature 310 (1984), S. 64-66 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Groups of female Brattleboro rats (200 g) were obtained from the Charing Cross Hospital Medical School; these animals were the products of homozygote-homozygote matings and were confirmed to have diabetes insipidus (urine output 〉 140 ml per day). Female Long-Evans rats of the same weight and ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/310064a0
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Immunohistochemical localization of oxytocin and vasopressin in the adrenal glands of rat, cow, hamster and guinea pig (1987)
    Springer
    Cell & tissue research 250 (1987), S. 1-6 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal gland ; Oxytocin ; Vasopressin ; Peptides ; Catecholamies ; Rat, cow, hamster, guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of oxytocin and vasopressin in the adrenals of rat, cow, hamster and guinea pig has been studied by use of immunohistochemical techniques. In all the species studied the adrenal cortex contained both peptides; the staining in the zona glomerulosa being more intense than that in zona fasciculata or zona reticularis. The medulla, however, showed considerable species variation. In the cow, both peptides appear to be present in the adrenergic and noradrenergic cells, though staining was particularly prominent in cortical islands interspersed within the medullary tissue. In the rat, groups of medullary cells positive for both peptides were found, though it was not possible to associate these groups with particular chromaffin cell types. In the hamster oxytocin was present only in adrenaline-containing cells, whereas vasopressin was present in all medullary cells. The guinea pig medulla, which contains only adrenaline-secreting cells, was positive for both peptides. The possibilities that vasopressin and oxytocin have an autocrine or paracrine role in functioning of the adrenal gland is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214646
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  • 3
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    The observed distribution of spectroscopic binaries from the Anglo-Australian Planet Search (2015)
    Oxford University Press
    Details
    Publication Date: 2015-08-27
    Description: We report the detection of sixteen binary systems from the Anglo-Australian Planet Search. Solutions to the radial velocity data indicate that the stars have companions orbiting with a wide range of masses, eccentricities and periods. Three of the systems potentially contain brown-dwarf companions while another two have eccentricities that place them in the extreme upper tail of the eccentricity distribution for binaries with periods less than 1000 d. For periods up to 12 years, the distribution of our stellar companion masses is fairly flat, mirroring that seen in other radial velocity surveys, and contrasts sharply with the current distribution of candidate planetary masses, which rises strongly below 10  M J . When looking at a larger sample of binaries that have FGK star primaries as a function of the primary star metallicity, we find that the distribution maintains a binary fraction of ~43 ± 4 per cent between –1.0 and +0.6 dex in metallicity. This is in stark contrast to the giant exoplanet distribution. This result is in good agreement with binary formation models that invoke fragmentation of a collapsing giant molecular cloud, suggesting that this is the dominant formation mechanism for close binaries and not fragmentation of the primary star's remnant protoplanetary disc.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 4
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    RAFT - I. Discovery of new planetary candidates and updated orbits from archival FEROS spectra (2015)
    Oxford University Press
    Details
    Publication Date: 2015-06-24
    Description: A recent reanalysis of archival data has lead several authors to arrive at strikingly different conclusions for a number of planet-hosting candidate stars. In particular, some radial velocities (RVs) measured using Fiber-fed Extended Range Optical Spectrograph (FEROS) spectra have been shown to be inaccurate, throwing some doubt on the validity of a number of planet detections. Motivated by these results, we have begun the Reanalysis of Archival FEROS specTra (RAFT) programme and here we discuss the first results from this work. We have reanalyzed FEROS data for the stars HD 11977, HD 47536, HD 70573, HD 110014 and HD 122430, all of which are claimed to have at least one planetary companion. We have reduced the raw data and computed the radial velocity variations of these stars, achieving a long-term precision of ~10 m s –1 on the known stable star Ceti, and in good agreement with the residuals to our fits. We confirm the existence of planets around HD 11977, HD 47536 and HD 110014, but with different orbital parameters than those previously published. In addition, we found no evidence of the second planet candidate around HD 47536, nor any companions orbiting HD 122430 and HD 70573. Finally, we report the discovery of a second planet around HD 110014, with a minimum mass of 3.1 M Jup and a orbital period of 130 d. Analysis of activity indicators allows us to confirm the reality of our results and also to measure the impact of magnetic activity on our RV measurements. These results confirm that very metal poor stars down to [Fe/H] ~ –0.7 dex, can indeed form giant planets given the right conditions.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 5
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    Immunohistochemical localization of oxytocin and vasopressin in the adrenal glands of rat, cow, hamster and guinea pig (1987)
    Springer
    Details
    Publication Date: 1987-10-01
    Print ISSN: 0302-766X
    Electronic ISSN: 1432-0878
    Topics: Biology , Medicine
    Published by Springer
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  • 6
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    Precision radial velocities of 15 M5-M9 dwarfs (2014)
    Oxford University Press
    Details
    Publication Date: 2014-03-21
    Description: We present radial velocity measurements of a sample of M5V–M9V stars from our Red-Optical Planet Survey, operating at 0.652–1.025 μm. Radial velocities for 15 stars, with rms precision down to 2.5 m s –1 over a week-long time-scale, are achieved using thorium–argon reference spectra. We are sensitive to planets with m p sin i ≥ 1.5 M (3 M at 2) in the classical habitable zone, and our observations currently rule out planets with m p sin i 〉 0.5 M J at 0.03 au for all our targets. A total of 9 of the 15 targets exhibit rms 〈 16 m s –1 , which enables us to rule out the presence of planets with m p sin i 〉 10 M in 0.03 au orbits. Since the mean rotation velocity is of the order of 8 km s –1 for an M6V star and 15 km s –1 for M9V, we avoid observing only slow rotators that would introduce a bias towards low axial inclination ( i 〈〈 90°) systems, which are unfavourable for planet detection. Our targets with the highest v sin  i values exhibit radial velocities significantly above the photon-noise-limited precision, even after accounting for v sin  i . We have therefore monitored stellar activity via chromospheric emission from the Hα and Ca ii infrared triplet lines. A clear trend of log 10 ( L Hα / L bol ) with radial velocity rms is seen, implying that significant starspot activity is responsible for the observed radial velocity precision floor. The implication that most late M dwarfs are significantly spotted, and hence exhibit time varying line distortions, indicates that observations to detect orbiting planets need strategies to reliably mitigate against the effects of activity-induced radial velocity variations.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 7
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    Discovery of a new Y dwarf: WISE J030449.03-270508.3 (2014)
    Oxford University Press
    Details
    Publication Date: 2014-09-07
    Description: We present a new Y dwarf, WISE J030449.03–270508.3, confirmed from a candidate sample designed to pick out low-temperature objects from the Wide-field Infrared Survey Explorer ( WISE ) data base. The new object is typed Y0pec following a visual comparison with spectral standards, and lies at a likely distance of 10–17 pc. Its tangential velocity suggests thin disc membership, but it shows some spectral characteristics that suggest that it may be metal poor and/or older than previously identified Y0 dwarfs. Based on trends seen for warmer late-type T dwarfs, the Y -band flux peak morphology is indicative of sub-solar metallicity, and the enhanced red wing of the J -band flux peak offers evidence for high gravity and/or low metallicity (with associated model trends suggesting an age closer to ~10 Gyr and mass in the range 0.02–0.03 M ). This object may thus be extending the population parameter space of the known Y0 dwarfs.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 8
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    Spectroscopic signatures of youth in low-mass kinematic candidates of young moving groups (2014)
    Oxford University Press
    Details
    Publication Date: 2014-03-25
    Description: We present a study of age-related spectral signatures observed in 25 young low-mass objects that we have previously determined as possible kinematic members of five young moving groups: the Local Association (Pleiades moving group, age = 20–150 Myr), the Ursa Major group (Sirius supercluster, age = 300 Myr), the Hyades supercluster (age = 600 Myr), IC 2391 supercluster (age = 35–55 Myr) and the Castor moving group (age = 200 Myr). In this paper we characterize the spectral properties of observed high- or low-resolution spectra of our kinematic members by fitting theoretical spectral distributions. We study signatures of youth, such as lithium i 6708Å, Hα emission and other age-sensitive spectroscopic signatures in order to confirm the kinematic memberships through age constraints. We find that 21 (84 per cent) targets show spectroscopic signatures of youth in agreement with the age ranges of the moving group to which membership is implied. For two further objects, age-related constraints remain difficult to determine from our analysis. In addition, we confirm two moving group kinematic candidates as brown dwarfs.
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    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 9
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    Improved signal detection algorithms for unevenly sampled data. Six signals in the radial velocity data for GJ876 (2014)
    Oxford University Press
    Details
    Publication Date: 2014-05-21
    Description: The hunt for Earth analogue planets orbiting Sun-like stars has forced the introduction of novel methods to detect signals at, or below, the level of the intrinsic noise of the observations. We present a new global periodogram method that returns more information than the classic Lomb–Scargle periodogram method for radial velocity signal detection. Our method uses the minimum mean-squared error as a framework to determine the optimal number of genuine signals present in a radial velocity timeseries using a global search algorithm, meaning that we can discard noise spikes from the data before a follow-up analysis. This method also allows us to determine the phase and amplitude of the signals we detect, meaning that we can track these quantities as a function of time to test if the signals are stationary or non-stationary. We apply our method to the radial velocity data for GJ876 as a test system to highlight how the phase information can be used to select against the non-stationary sources of detected signals in radial velocity data, such as rotational modulation of star spots. Analysis of this system yields two new statistically significant signals in the combined Keck and HARPS velocities with periods of 10 and 15 d. Although a planet with a period of 15 d would relate to a Laplace resonant chain configuration with three of the other planets (8:4:2:1), we stress that the follow-up dynamical analyses are needed to test the reliability of such a six-planet system.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 10
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    Bayesian search for low-mass planets around nearby M dwarfs - estimates for occurrence rate based on global detectability statistics (2014)
    Oxford University Press
    Details
    Publication Date: 2014-05-11
    Description: Due to their higher planet–star mass ratios, M dwarfs are the easiest targets for detection of low-mass planets orbiting nearby stars using Doppler spectroscopy. Furthermore, because of their low masses and luminosities, Doppler measurements enable the detection of low-mass planets in their habitable zones that correspond to closer orbits than for solar-type stars. We re-analyse literature Ultraviolet and Visual Echelle Spectrograph (UVES) radial velocities of 41 nearby M dwarfs in a combination with new velocities obtained from publicly available spectra from the HARPS-ESO spectrograph of these stars in an attempt to constrain any low-amplitude Keplerian signals. We apply Bayesian signal detection criteria, together with posterior sampling techniques, in combination with noise models that take into account correlations in the data and obtain estimates for the number of planet candidates in the sample. More generally, we use the estimated detection probability function to calculate the occurrence rate of low-mass planets around nearby M dwarfs. We report eight new planet candidates in the sample (orbiting GJ 27.1, GJ 160.2, GJ 180, GJ 229, GJ 422, and GJ 682), including two new multiplanet systems, and confirm two previously known candidates in the GJ 433 system based on detections of Keplerian signals in the combined UVES and High Accuracy Radial velocity Planet Searcher (HARPS) radial velocity data that cannot be explained by periodic and/or quasi-periodic phenomena related to stellar activities. Finally, we use the estimated detection probability function to calculate the occurrence rate of low-mass planets around nearby M dwarfs. According to our results, M dwarfs are hosts to an abundance of low-mass planets and the occurrence rate of planets less massive than 10 M is of the order of one planet per star, possibly even greater. Our results also indicate that planets with masses between 3 and 10 M are common in the stellar habitable zones of M dwarfs with an estimated occurrence rate of 0.21 $^{+0.03}_{-0.05}$ planets per star.
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    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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