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  • 1
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    Raphe inhibition of sympathetic preganglionic neurons (1979)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1979-01-12
    Description: Anatomical and electrophysiological studies suggest that the medullary raphe gives rise to a monosynaptic, inhibitory projection on sympathetic preganglionic neurons. Physiological and behavioral data indicate that this sympathoinhibitory pathway participates in the central control of cardiovascular function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cabot, J B -- Wild, J M -- Cohen, D H -- New York, N.Y. -- Science. 1979 Jan 12;203(4376):184-6.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/758687" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Autonomic Fibers, Preganglionic/physiology ; Blood Pressure ; Brain Stem/*physiology ; Columbidae ; Electric Stimulation ; Heart/*physiology ; Heart Rate ; *Neural Inhibition ; Neural Pathways/cytology/physiology ; Raphe Nuclei/cytology/*physiology ; Spinal Cord/*physiology ; Sympathetic Nervous System/cytology/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Modification of the discharge of vagal cardiac neurons during learned heart rate change (1981)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1981-10-16
    Description: Visually conditioned heart rate change in the pigeon has been developed as a vertebrate model system for the cellular neurophysiological analysis of associative learning. In previous studies of the "final common path," it was shown that both the vagal and sympathetic cardiac innervations contribute to this response. The present experiments indicate that, prior to any behavioral training, the visual stimulus elicits a small decrease in the discharge of vagal cardiac neurons. During conditioning, this stimulus evokes a progressively greater decrease in discharge that parallels the acquisition of the conditioned cardioacceleration. In contrast, nonassociative control animals show habituation of the initial decrease in discharge. These data confirm the involvement of the vagal cardiac innervation in conditioned heart rate change, indicate that the vagal innervation acts synergistically with the sympathetic to produce cardioacceleration, and suggest that a short-latency pathway mediates the conditioned response.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gold, M R -- Cohen, D H -- P01 NS 14620/NS/NINDS NIH HHS/ -- T32 HL07284/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1981 Oct 16;214(4518):345-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7280698" target="_blank"〉PubMed〈/a〉
    Keywords: Action Potentials ; Animals ; Association Learning/*physiology ; Columbidae/physiology ; Conditioning (Psychology)/physiology ; Heart/*innervation ; Heart Rate ; Learning/*physiology ; Light ; Time Factors ; Vagus Nerve/*physiology ; Visual Pathways/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
    Electronic Resource
    Electronic Resource
    Classical Conditioning of Cardiovascular Responses (1984)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 46 (1984), S. 187-197 
    Details
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ph.46.030184.001155
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    Paper (German National Licenses)
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  • 4
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    An 'analytic dynamical magnetosphere formalism for X-ray and optical emission from slowly rotating magnetic massive stars (2016)
    Oxford University Press
    Details
    Publication Date: 2016-09-03
    Description: Slowly rotating magnetic massive stars develop ‘dynamical magnetospheres’ (DMs), characterized by trapping of stellar wind outflow in closed magnetic loops, shock heating from collision of the upflow from opposite loop footpoints, and subsequent gravitational infall of radiatively cooled material. In 2D and 3D magnetohydrodynamic (MHD) simulations, the interplay among these three components is spatially complex and temporally variable, making it difficult to derive observational signatures and discern their overall scaling trends. Within a simplified, steady-state analysis based on overall conservation principles, we present here an ‘analytic dynamical magnetosphere’ (ADM) model that provides explicit formulae for density, temperature, and flow speed in each of these three components – wind outflow, hot post-shock gas, and cooled inflow – as a function of colatitude and radius within the closed (presumed dipole) field lines of the magnetosphere. We compare these scalings with time-averaged results from MHD simulations, and provide initial examples of application of this ADM model for deriving two key observational diagnostics, namely hydrogen H α emission line profiles from the cooled infall, and X-ray emission from the hot post-shock gas. We conclude with a discussion of key issues and advantages in applying this ADM formalism towards derivation of a broader set of observational diagnostics and scaling trends for massive stars with such dynamical magnetospheres.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 5
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    Confirming HD 23478 as a new magnetic B star hosting an H{alpha}-bright centrifugal magnetosphere (2015)
    Oxford University Press
    Details
    Publication Date: 2015-06-11
    Description: In this paper, we report 23 magnetic field measurements of the B3IV star HD 23478: 12 obtained from high-resolution Stokes V spectra using the ESPaDOnS (Canada–France–Hawaii Telescope) and Narval (Télescope Bernard Lyot) spectropolarimeters, and 11 from medium-resolution Stokes V spectra obtained with the DimaPol spectropolarimeter (Dominion Astronomical Observatory). HD 23478 was one of two rapidly rotating stars identified as potential ‘centrifugal magnetosphere’ hosts based on IR observations from the Apache Point Observatory Galactic Evolution Experiment survey. We derive basic physical properties of this star including its mass ( $M=6.1^{+0.8}_{-0.7}\,\mathrm{M}_{\odot }$ ), effective temperature ( T eff  = 20 ± 2 kK), radius ( $R=2.7^{+1.6}_{-0.9}\,\mathrm{R}_{\odot }$ ), and age ( $\tau _{\rm age}=3^{+37}_{-1}\,{\rm Myr}$ ). We repeatedly detect weakly variable Zeeman signatures in metal, He, and H lines in all our observations corresponding to a longitudinal magnetic field of 〈 B z 〉  –2.0 kG. The rotational period is inferred from Hipparcos photometry ( P rot  = 1.0498(4) d). Under the assumption of the Oblique Rotator Model, our observations yield a surface dipole magnetic field of strength B d  ≥ 9.5 kG that is approximately aligned with the stellar rotation axis. We confirm the presence of strong and broad Hα emission and gauge the volume of this star's centrifugal magnetosphere to be consistent with those of other Hα emitting centrifugal magnetosphere stars based on the large inferred Alfvén to Kepler radius ratio.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 6
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    Detection of 610-MHz radio emission from hot magnetic stars (2015)
    Oxford University Press
    Details
    Publication Date: 2015-07-16
    Description: We have carried out a study of radio emission from a small sample of magnetic O- and B-type stars using the Giant Metrewave Radio Telescope, with the goal of investigating their magnetospheres at low frequencies. These are the lowest frequency radio measurements ever obtained of hot magnetic stars. The observations were taken at random rotational phases in the 1390 and the 610 MHz bands. Out of the eight stars, we detect five B-type stars in both the 1390 and the 610 MHz bands. The three O-type stars were observed only in the 1390 MHz band, and no detections were obtained. We explain this result as a consequence of free–free absorption by the free-flowing stellar wind exterior to the confined magnetosphere. We also study the variability of individual stars. One star – HD 133880 – exhibits remarkably strong and rapid variability of its low-frequency flux density. We discuss the possibility of this emission being coherent emission as reported for CU Vir by Trigilio et al.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 7
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    The MiMeS survey of magnetism in massive stars: introduction and overview (2015)
    Oxford University Press
    Details
    Publication Date: 2015-12-13
    Description: The MiMeS (Magnetism in Massive Stars) project is a large-scale, high-resolution, sensitive spectropolarimetric investigation of the magnetic properties of O- and early B-type stars. Initiated in 2008 and completed in 2013, the project was supported by three Large Program allocations, as well as various programmes initiated by independent principal investigators, and archival resources. Ultimately, over 4800 circularly polarized spectra of 560 O and B stars were collected with the instruments ESPaDOnS (Echelle SpectroPolarimetric Device for the Observation of Stars) at the Canada–France–Hawaii Telescope, Narval at the Télescope Bernard Lyot and HARPSpol at the European Southern Observatory La Silla 3.6 m telescope, making MiMeS by far the largest systematic investigation of massive star magnetism ever undertaken. In this paper, the first in a series reporting the general results of the survey, we introduce the scientific motivation and goals, describe the sample of targets, review the instrumentation and observational techniques used, explain the exposure time calculation designed to provide sensitivity to surface dipole fields above approximately 100 G, discuss the polarimetric performance, stability and uncertainty of the instrumentation, and summarize the previous and forthcoming publications.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 8
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    Measuring mass-loss rates and constraining shock physics using X-ray line profiles of O stars from the Chandra archive (2014)
    Oxford University Press
    Details
    Publication Date: 2014-03-01
    Description: We quantitatively investigate the extent of wind absorption signatures in the X-ray grating spectra of all non-magnetic, effectively single O stars in the Chandra archive via line profile fitting. Under the usual assumption of a spherically symmetric wind with embedded shocks, we confirm previous claims that some objects show little or no wind absorption. However, many other objects do show asymmetric and blueshifted line profiles, indicative of wind absorption. For these stars, we are able to derive wind mass-loss rates from the ensemble of line profiles, and find values lower by an average factor of 3 than those predicted by current theoretical models, and consistent with Hα if clumping factors of f cl 20 are assumed. The same profile fitting indicates an onset radius of X-rays typically at r 1.5 R * , and terminal velocities for the X-ray emitting wind component that are consistent with that of the bulk wind. We explore the likelihood that the stars in the sample that do not show significant wind absorption signatures in their line profiles have at least some X-ray emission that arises from colliding wind shocks with a close binary companion. The one clear exception is Oph, a weak-wind star that appears to simply have a very low mass-loss rate. We also reanalyse the results from the canonical O supergiant Pup, using a solar-metallicity wind opacity model and find $\dot{M}= 1.8 \times 10^{-6}$ ${\mathrm{M_{\odot }\,{\mathrm{y}r^{-1}}}}$ , consistent with recent multiwavelength determinations.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 9
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    Measuring the shock-heating rate in the winds of O stars using X-ray line spectra (2014)
    Oxford University Press
    Details
    Publication Date: 2014-09-19
    Description: We present a new method for using measured X-ray emission line fluxes from O stars to determine the shock-heating rate due to instabilities in their radiation-driven winds. The high densities of these winds means that their embedded shocks quickly cool by local radiative emission, while cooling by expansion should be negligible. Ignoring for simplicity any non-radiative mixing or conductive cooling, the method presented here exploits the idea that the cooling post-shock plasma systematically passes through the temperature characteristic of distinct emission lines in the X-ray spectrum. In this way, the observed flux distribution among these X-ray lines can be used to construct the cumulative probability distribution of shock strengths that a typical wind parcel encounters as it advects through the wind. We apply this new method to Chandra grating spectra from five O stars with X-ray emission indicative of embedded wind shocks in effectively single massive stars. The results for all the stars are quite similar: the average wind mass element passes through roughly one shock that heats it to at least 10 6  K as it advects through the wind, and the cumulative distribution of shock strengths is a strongly decreasing function of temperature, consistent with a negative power law of index n 3, implying a marginal distribution of shock strengths that scales as T –4 , and with hints of an even steeper decline or cut-off above 10 7  K.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 10
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    Them1 regulates energy expenditure [Medical Sciences] (2012)
    National Academy of Sciences
    Details
    Publication Date: 2012-04-04
    Description: Mammalian acyl-CoA thioesterases (Acots) catalyze the hydrolysis of fatty acyl-CoAs to form free fatty acids plus CoA, but their metabolic functions remain undefined. Thioesterase superfamily member 1 (Them1; synonyms Acot11, StarD14, and brown fat inducible thioesterase) is a long-chain fatty acyl-CoA thioesterase that is highly expressed in brown adipose tissue and is regulated by both ambient temperature and food consumption. Here we show that Them1−/− mice were resistant to diet-induced obesity despite greater food consumption. Them1−/− mice exhibited increased O2 consumption and heat production, which were accompanied by increased rates of fatty acid oxidation in brown adipose tissue and up-regulation of genes that promote energy expenditure. Them1−/− mice were also protected against diet-induced inflammation in white adipose tissue, as well as hepatic steatosis, and demonstrated improved glucose homeostasis. The absence of Them1 expression in vivo and in cell culture led to markedly attenuated diet- or chemically induced endoplasmic reticulum stress responses, providing a mechanism by which Them1 deficiency protects against insulin resistance and lipid deposition. Taken together, these data suggest that Them1 functions to decrease energy consumption and conserve calories. In the setting of nutritional excess, the overproduction of free fatty acids by Them1 provokes insulin resistance that is associated with inflammation and endoplasmic reticulum stress.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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